# Patent

## Title
RAAV-based compositions and methods for treating alpha-1 anti-trypsin deficiencies

## Abstract

The invention relates to isolated nucleic acids and rAAV-based compositions, methods and kits useful for treating genetic diseases (e.g., alpha-1 antitrypsin deficiency).

## Background
RELATED APPLICATIONS
This application is a National State Application PCT/US2012/034446, field on Apr. 20, 2012, and entitled “RAAV-BASED COMPOSITIONS AND METHODS FOR TREATING ALPHA-1 ANTI-TRYPSIN DEFICIENCIES,” which claims priority under 35 U.S.C. §119(e) to U.S. Provisional Application Ser. No. 61/477,671, entitled “RAAV-BASED COMPOSITIONS AND METHODS FOR TREATING ALPHA-1 ANTI-TRYPSIN DEFICIENCIES” filed on Apr. 21, 2011, which is herein incorporated by reference in its entirety.


FEDERALLY SPONSORED RESEARCH
This invention was made with Government support from the National Institutes of Health under Grant Numbers HL69877 and P30 DK 32520. The Government has certain rights in the invention.


FIELD OF THE INVENTION
The invention relates to methods and compositions for treating genetic disease using rAAV-based vectors.
BACKGROUND OF THE INVENTION
Numerous diseases are associated with inherited or somatic mutations. In many cases, these mutations are present in the transcript region of genes, the products of which control important physiological functions including, for example, gene expression, cell signaling, tissue structure, and the metabolism and catabolism of various biomolecules. Mutations in these genes, which are often only single nucleotide changes (e.g., non-sense mutations, missense mutations), can have negative effects on the expression, stability and/or function of the gene product resulting in alterations in one or more physiological functions.
A number of different mutations have been identified in the Alpha-1 antitrypsin (AAT) gene. AAT is one of the primary circulating serum anti-proteases in humans. AAT inhibits a variety of serine proteinases, with neutrophil elastase being one of the most physiologically important, as well as inhibiting a number of metalloproteinases and other pro-inflammatory and pro-apoptotic molecules. AAT is normally produced within hepatocytes and macrophages, where hepatocyte-derived AAT forms the bulk of the physiologic reserve of AAT.
Approximately 4% of the North American and Northern European populations possess at least one copy of a mutant allele, known as PI*Z (Z-AAT) which results from a single amino acid substitution of lysine for glutamate at position 342 in the mature protein (position 366 in the precursor protein). In the homozygous state, this mutation leads to severe deficiency of AAT, and can result in two distinct pathologic states: a lung disease which is primarily due to the loss of antiprotease function, and a liver disease (present to a significant degree in approximately 10-15% of patients) due to a toxic gain of function of the Z-AAT mutant protein.
Investigational clinical gene therapy products for gene augmentation of AAT have been developed as potential treatments for lung disease using the recombinant adeno-associated viral (rAAV) vectors. Researchers have also applied genetic technologies in an effort to down-regulate the levels of AAT mRNA. One approach was to utilize hammerhead ribozymes designed to cleave AAT mRNA at a specific site. Another approach involves the use of RNA interference to decrease levels of the mutant mRNA transcript.
SUMMARY OF THE INVENTION
Aspects of the invention relate to improved gene therapy-based methods for treating genetic disease. Some aspects of the invention relate to improved gene therapy compositions and related methodology for treating lung disease and/or liver disease using the recombinant adeno-associated viral vectors. In some embodiments, the methods utilize rAAV (e.g., rAAV9, rAAV2, rAAV1) based vectors for augmenting AAT expression. In some embodiments, compositions and methods are provided for decreasing the expression of Pi*Z mutant AAT protein. In such embodiments, the compositions and methods are useful for halting and/or ameliorating hepatocellular damage and other tissue damage associated with the mutant AAT.
According to some aspects of the invention, the compositions and methods are useful for knocking down PiZ protein while at the same time increasing levels of the M-AAT protein (the wild-type AAT protein). In some embodiments, a non-toxic dual function vector is provided that is capable of knocking-down Z-AAT while augmenting M-AAT. According to some embodiments, methods and compositions for long-term expression of therapeutic miRNAs are provided that utilize the recombinant adeno-associated virus (rAAV) platform. In some embodiments, therapeutic compositions and methods described herein take advantage of the miRNA pathway by altering the seed sequence of natural miRNAs to target the endogenous AAT gene. In some embodiments, the methods are safer and less toxic than shRNA-based approaches.
According to other aspects of the invention, rAAV-based compositions and methods are provided that simultaneously direct silencing agents to the liver to decrease Z-AAT expression and direct gene augmentation to other sites. However, in some embodiments, the liver is an optimal target tissue for augmentation. In some embodiments, a miRNA-based approach is provided to stably down-regulate Z-AAT within hepatocytes. In some embodiments, the approach allows for simultaneous M-AAT gene augmentation from the same rAAV gene delivery vector without serious perturbation of the overall hepatic miRNA profile. In some embodiments, the specific vector used is a systemically delivered rAAV9-capsid derived vector. According to some aspects of the invention, this approach has broad utility in genetic disorders stemming from dominant negative and gain of function mutations as well as for delivering artificial miRNAs to be delivered in conjunction with therapeutic genes.
According to some aspects of the invention, isolated nucleic acids are provided. In some embodiments, the isolated nucleic acids comprise (a) a first region that encodes one or more first miRNAs comprising a nucleic acid having sufficient sequence complementary with an endogenous mRNA of a subject to hybridize with and inhibit expression of the endogenous mRNA, wherein the endogenous mRNA encodes a first protein; and (b) a second region encoding an exogenous mRNA that encodes a second protein, wherein the second protein has an amino acid sequence that is at least 85% identical to the first protein, wherein the one or more first miRNAs do not comprise a nucleic acid having sufficient sequence complementary to hybridize with and inhibit expression of the exogenous mRNA, and wherein the first region is positioned within an untranslated portion of the second region. In some embodiments, the untranslated portion is an intron. In some embodiments, the first region is between the first codon of the exogenous mRNA and 1000 nucleotides upstream of the first codon.
In some embodiments, the isolated nucleic acids comprise (a) a first region encoding one or more first miRNAs comprising a nucleic acid having sufficient sequence complementary with an endogenous mRNA of a subject to hybridize with and inhibit expression of the endogenous mRNA, wherein the endogenous mRNA encodes a first protein; and (b) a second region encoding an exogenous mRNA that encodes a second protein, wherein the second protein has an amino acid sequence that is at least 85% identical to the first protein, wherein the one or more first miRNAs do not comprise a nucleic acid having sufficient sequence complementary to hybridize with and inhibit expression of the exogenous mRNA, and wherein the first region is positioned downstream of a portion of the second region encoding the poly-A tail of the exogenous mRNA.
In some embodiments, the isolated nucleic acids further comprise a third region encoding a one or more second miRNAs comprising a nucleic acid having sufficient sequence complementary to hybridize with and inhibit expression of the endogenous mRNA, wherein the third region is positioned within an untranslated portion of the second region. In some embodiments, the untranslated portion is an intron. In some embodiments, the first region is between the last codon of the exogenous mRNA and a position 1000 nucleotides downstream of the last codon. In some embodiments, the third region is between the first codon of the exogenous mRNA and a position 1000 nucleotides upstream of the first codon.
In some embodiments of the isolated nucleic acids, the first region encodes two first miRNAs. In some embodiments, the first region encodes three first miRNAs. In some embodiments, the third region encodes two second miRNAs. In some embodiments, the third region encodes three second miRNAs. In some embodiments, one or more of the first miRNAs have the same nucleic acid sequence as one or more of the second miRNAs. In some embodiments, each of the first miRNAs has the same nucleic acid sequence as one of the second miRNAs. In some embodiments, the second protein has an amino acid sequence that is at least 90% identical to the first protein. In some embodiments, the second protein has an amino acid sequence that is at least 95% identical to the first protein. In some embodiments, the second protein has an amino acid sequence that is at least 98% identical to the first protein. In some embodiments, the second protein has an amino acid sequence that is at least 99% identical to the first protein. In some embodiments, the second protein has an amino acid sequence that is 100% identical to the first protein.
In some embodiments of the isolated nucleic acids, the first protein is Alpha 1-Antitrypsin (AAT) protein. In some embodiments, the AAT protein is a human AAT protein. In some embodiments, the AAT protein has sequence as set forth in SEQ ID NO: 1 or 2 or one or more mutations thereof as identified in Table 1, e.g. SEQ ID NO: 3 or 4. In some embodiments, the first mRNA comprises a nucleic acid encoded by a sequence as set forth in SEQ ID NOS: 5-16. In some embodiments, the one or more miRNAs have a nucleic acid sequence encoded by a sequence from the group consisting of SEQ ID NOS: 17-19 and 21-23. In some embodiments of the isolated nucleic acids, the exogenous mRNA has one or more silent mutations compared with the endogenous mRNA. In some embodiments, the exogenous mRNA has a nucleic acid sequence encoded by a sequence as set forth in SEQ ID NO: 20.
In some embodiments, the isolated nucleic acids further comprise an inverted terminal repeats (ITR) of an AAV serotypes selected from the group consisting of: AAV1, AAV2, AAV5, AAV6, AAV6.2, AAV7, AAV8, AAV9, AAV10, AAV11 and variants thereof. In some embodiments, the isolated nucleic acids further comprise a promoter operably linked with the region(s) encoding the one or more first miRNAs, the exogenous mRNA, and/or the one or more second miRNAs. In certain embodiments, the promoter is a tissue-specific promoter. In certain embodiments, the promoter is a β-actin promoter.
According to some aspects of the invention, recombinant Adeno-Associated Viruses (AAVs) are provided that comprise any of the isolated nucleic acids disclosed herein. In some embodiments, the recombinant AAVs further comprise one or more capsid proteins of one or more AAV serotypes selected from the group consisting of: AAV1, AAV2, AAV3, AAV4, AAV5, AAV6, AAV7, AAV8, AAV9, AAV10, AAV11 and variants thereof.
According to some aspects of the invention, compositions are provided that comprise any of the isolated nucleic acids disclosed herein. According to some aspects of the invention, compositions are provided that comprise any of the recombinant AAVs disclosed herein. In some embodiments, the compositions further comprise a pharmaceutically acceptable carrier.
According to some aspects of the invention, kits are provided that comprise one or more containers housing a composition, isolated nucleic acid or rAAV of the invention. In some embodiments, the kits further comprise written instructions for administering an rAAV to a subject.
According to some aspects of the invention, methods are provided for expressing Alpha 1-Antitrypsin (AAT) protein in a subject. In some embodiments, the methods comprise administering to a subject an effective amount of any recombinant Adeno-Associated Virus (rAAV) disclosed herein. In some embodiments, the rAAV is administered with a pharmaceutically acceptable carrier.
In some embodiments of the methods, the subject has or suspected of having an Alpha 1-Antitrypsin deficiency. In certain embodiments, the subject has a mutation in an AAT gene. In certain embodiments, the mutation encodes a mutant AAT protein. In some embodiments, the methods further comprise determining that the subject has the mutation. In certain embodiments, the mutation is a mutation listed in Table 1. In certain embodiments, the mutation is a missense mutation. In certain embodiments, the mutation results in a glutamate to lysine substitution at amino acid position 366 according to the amino acid sequence set forth as SEQ ID NO: 3. In certain embodiments, the mutant AAT protein fails to fold properly.
In some embodiments of the methods, the effective amount of rAAV is 1010, 1011, 1012, or 1013 genome copies. In some embodiments, administering is performed intravascularly, intravenously, intrathecally, intraperatoneally, intramuscularly, subcutaneously or intranasally. In certain embodiments, administering is performed by injection into the hepatic portal vein.
In some embodiments of the methods, administering is performed ex vivo by isolating cells or tissue from a subject, contacting the cell or tissue with an effective amount of an rAAV, thereby producing transfected cells or tissue, and administering the transfected cells or tissue to the subject. In certain embodiments, the tissue is adipose tissue. In certain embodiments, the cells are stem cells derived from adipose tissue. In some embodiments, administering the transfected cells is performed intravascularly, intravenously, intrathecally, intraperatoneally, intramuscularly, subcutaneously or intranasally. In certain embodiments, administering the transfected cells is performed by transplantation of transfected cells into a target tissue. In certain embodiments, the target tissue is lung or liver
In some embodiments of the methods, the subject is a mouse, a rat, a rabbit, a dog, a cat, a sheep, a pig, a non-human primate or a human. In certain embodiments, the subject is a human.
In some embodiments of the methods, after administration of the rAAV the level of expression of the first protein is determined in the subject. In some embodiments, after administration of the rAAV the level of expression of the second protein is determined in the subject. In some embodiments, administering is performed on two or more occasions. In certain embodiments, the level of the first protein and/or the level of the second protein in the subject are determined after at least one administration.
In some embodiments of the methods, the serum level of the first protein in the subject is reduced by at least 85% following administration of the rAAV. In some embodiments, the serum level of the first protein in the subject is reduced by at least 90% following administration of the rAAV. In some embodiments, the serum level of the first protein in the subject is reduced by at least 95% following administration of the rAAV. In some embodiments, the serum level of the first protein in the subject is reduced by at least 85% within 2 weeks following administration of the rAAV. In some embodiments, the serum level of the first protein in the subject is reduced by at least 90% within 2 weeks following administration of the rAAV. In some embodiments, the serum level of the first protein in the subject is reduced by at least 85% within 4 weeks of administration of the rAAV. In some embodiments, after 7 weeks of administration of the rAAV, the serum level of the first protein is at a level of at least 50% compared with the serum level of the first protein prior to administration of the rAAV. In some embodiments, after 7 weeks of administration of the rAAV, the serum level of the first protein is at a level of at least 75% compared with the serum level of the first protein prior to administration of the rAAV.
In some embodiments of the methods, after administration of the rAAV at least one clinical outcome parameter associated with the AAT deficiency is evaluated in the subject. In some embodiments, the at least one clinical outcome parameter evaluated after administration of the rAAV is compared with the at least one clinical outcome parameter determined prior to administration of the rAAV to determine effectiveness of the rAAV, wherein an improvement in the clinical outcome parameter after administration of the rAAV indicates effectiveness of the rAAV. In some embodiments, the clinical outcome parameter is selected from the group consisting of: serum levels of the first protein, serum levels of the second protein, presence of intracellular AAT globules, presence of inflammatory foci, breathing capacity, cough frequency, phlegm production, frequency of chest colds or pneumonia, and tolerance for exercise. In some embodiments, the intracellular AAT globules or inflammatory foci are evaluated in lung tissue or liver tissue.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 Comparison of shRNA and miRNA mediated knockdown of human AAT. HEK-293 cells were contrasfected with human Z-AAT plasmid and either a plasmid expressing 3 anti-AAT shRNAs from a U6 promoter or a plasmid expressing 3 anti-AAT miRNA from a hybrid chicken beta actin promoter. (a) Culture media was harvested at 24, 48 and 72 hours and was analyzed for the AAT concentration by ELISA. (b) At 72 hours cells were harvested and lysed for AAT concentration by ELISA. *<0.05 as determined by a two-way unpaired student t-test.
FIG. 2 In vivo silencing of human AAT by rAAV9 expressed miRNAs. Transgenic mice expressing the human PiZ allele were injected with 5×1011 vector particles or rAAV9 expressing miRNAs against AAT under the control of the hybrid chicken beta-actin promoter via the tail vein. Serums from each cohort were collected on a weekly basis and were used to assess Z-AAT concentration by ELISA. Data is expressed as group means+SEM (n=6).
FIG. 3 Liver histology for PiZ transgenic mice 5 weeks post-rAAV9 delivery. Livers from mice receiving rAAV9 vectors with miRNAs and GFP controls were formalin-fixed and stained for AAT, or with a PAS-D assay. Mouse liver sections stained using an anti-human AAT antibody from a mouse treated with (a) intronic-3XmiR or (b) GFP controls. Mouse Liver sections stained with diastase-resistant Periodic Acid Schiff assay from (e&f) intronic-3XmiR or (c&d) GFP controls. (g) Quantitative pixel image analysis of whole liver sections was performed by comparing pixel counts of PASD-positive globules in GFP controls (N=7) to pixel counts of PASD-positive globules in intronic-3XmiR (N=7).
FIG. 4 In vivo optimization of anti-AAT miRNA delivery within rAAV9 vectors. Transgenic mice expressing the human PiZ allele were injected with 5×1011 vector particles or rAAV9 expressing miRNAs against AAT under the control of the hybrid chicken beta-actin promoter via the tail vein. Serums from each cohort were collected on a weekly basis and were used to assess Z-AAT concentration by ELISA.
FIG. 5 Quantitative RT-PCR for artificial miRNA in vivo. Total RNA from mouse livers was used to assay for the presence of the 3 artificial anti-AAT miRNAs from mice receiving rAAV9-miRNA vectors. *<0.05 as determined by a two-way unpaired student t-test.
FIG. 6 Long-term In vivo silencing of human AAT by rAAV9 expressed miRNAs. Transgenic mice expressing the human PiZ allele were injected with 1×1012 vector particles or rAAV9 expressing miRNAs against AAT under the control of the hybrid chicken beta-actin promoter via the tail vein. (a) Serums from each cohort were collected on a weekly basis and were used to assess Z-AAT concentration by ELISA. (b) ATT from liver lysates of mice was analyzed by immunoblot after monomer and polymer separation. The 52 kDa Z-AAT was from livers processed and separated into a monomer and polymer pool. Densitometric analysis was performed for the (c) monomer and (d) polymer pools using Image J software. Baseline serums and those collected two weeks-post rAAV9 delivery were used to analyze liver function as determined by (e) ALT and (f) AST concentration. Data is expressed as group means+SEM. *<0.05 as determined by a two-way unpaired student t-test comparing rAAV9 cohorts vs. baseline.
FIG. 7 In vitro assessment of dual-function pro-viral plasmid. HEK-293 cells were contrasfected with human Z-AAT plasmid and either the Double-6XmiR-CB-AAT plasmid, a GFP or PBS control. Cells were processed for RNA at 72 hours and were analyzed for (a) PiZ-mRNA or (b) PiM mRNA with qRT-PCR. Data is expressed as group means+SEM (n=6). *<0.05 as determined by a two-way unpaired student t-test.
FIG. 8 In vivo knockdown of Z-AAT with simultaneous augmentation of M-AAT after rAAV9 dual function vector delivery. Transgenic mice expressing the human PiZ allele were injected with 1×1012 vector particles or rAAV9 expressing miRNAs against AAT and a de-targeted cMyc tagged wildtype M-AAT cDNA under the control of the hybrid chicken beta-actin promoter via the tail vein. (a) Serum from each cohort was collected on a weekly basis and was used to assess Z-AAT concentration by Z-AAT specific ELISA and M-AAT levels by cMyc ELISA. Total RNA from mouse livers was used to assay for the presence of the either (b) Z-AAT mRNA or (c) M-AAT mRNA by qRT-PCR. Data is expressed as group means+SEM (n=6). *<0.05 as determined by a two-way unpaired student t-test.
FIG. 9 Artificial miRNA have minimal impact on endogenous miRNA liver profiles. Liver RNA was harvested 3 months post delivery from animals injected with the following vectors: intronic-3XmiR-GFP, PolyA-3XmiR-GFP, Double-6XmiR-GFP, CB-GFP along with RNA form untreated PiZ mice and wildtype C57B16 mice was used to run a miRNA microarray. Each group consisted of 5 mouse RNA samples and was run independently with a single color (Cy5) microarray.



DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS OF THE INVENTION
Aspects of the invention relate to improved gene therapy compositions and related methods for treating Alpha-1 Antitrypsin (AAT, also sometimes called SERPINA1) deficiencies using the recombinant adeno-associated viral (rAAV) vectors. In some embodiments, a non-toxic dual function vector is provided that is capable of knocking-down mutant AAT while expressing wild-type AAT. The rAAV-based vectors and related methods provide for long-term expression of therapeutic miRNAs and expression of wild-type protein. According to other aspects, rAAV-based compositions and methods are provided that simultaneously direct silencing agents to the liver to decrease Z-AAT expression and direct gene expression to other sites (e.g., lung tissue). In some embodiments, compositions and methods are provided that are useful for treating the AAT deficiency by knocking down PiZ protein (a mutant AAT protein) while at the same time increasing levels of the M-AAT protein (the wild-type AAT protein). It will be appreciated that the rAAV-based therapeutic approaches disclosed herein can be applied to other gain-of-function or dominant-negative genetic disorders such as Huntington's disease, which previously have not been amiable to a single vector gene therapy approach.
Certain rAAV vectors provided herein incorporate miRNA sequences targeting the AAT gene while driving the expression of hardened wild-type AAT gene (a wild-type AAT gene that is not targeted by the miRNA), thus achieving concomitant mutant AAT knockdown e.g., in the liver, with increased expression of wildtype AAT. In one embodiment, transgenic mice expressing the human PiZ allele were injected with control or dual function rAAV9 vectors expressing both miRNAs and a hardened AAT gene with a cMyc tag. In this embodiment, serum PiZ levels were consistently knocked down by an average of 80% from baseline levels with the knockdown being stable and persistent over a 13 week period. In one embodiment, cohorts receiving dual function vectors exhibited knockdown of PiZ AAT while secreting increased serum levels of wild-type AAT as determined by a PiZ and PiM specific ELISAs. In this embodiment, liver histology revealed significantly decreased globular accumulation of misfolded PiZ AAT in hepatocytes along with a reduction in inflammatory infiltrates when compared to controls.
In one embodiment, global miRNA expression profiles of the liver were minimally affected by artificial miRNAs delivered via rAAV, with only a few miRNAs showing statistically significant differences. In one embodiment, a difference was seen in miR-1 which was reduced in PiZ transgenic mice receiving rAAV vectors to normal levels seen in wild-type B6 mice. In one embodiment, the levels of miR-122 were unaffected in all mice receiving rAAVs expressing miRNA targeting the AAT gene. Accordingly, in some embodiments, dual function rAAV vectors are effective at knocking down PIZ AAT while simultaneously augmenting wild-type AAT without disturbing endogenous miRNA liver profiles.
Alpha-1 Antitrypsin Deficiency
Alpha-1 antitrypsin (AAT), also known in the art as serpin peptidase inhibitor, clade A (SERPINA1), is a protein that functions as proteinase (protease) inhibitor. AAT is mainly produced in the liver, but functions in the lungs and liver, primarily. As used herein the term, “alpha-1 antitrypsin deficiency” refers to a condition resulting from a deficiency of functional AAT in a subject. In some embodiments, a subject having an AAT deficiency produces insufficient amounts of alpha-1 antitrypsin. In some embodiments, a subject having an AAT deficiency produces a mutant AAT. In some embodiments, insufficient amounts of AAT or expression of mutant AAT results in damage to a subject's lung and/or liver. In some embodiments, the AAT deficiency leads to emphysema and/or liver disease. Typically, AAT deficiencies result from one or more genetic defects in the AAT gene. The one or more defects may be present in one or more copies (e.g., alleles) of the AAT gene in a subject. Typically, AAT deficiencies are most common among Europeans and North Americans of European descent. However, AAT deficiencies may be found in subjects of other descents as well.
Subjects (e.g., adult subjects) with severe AAT deficiencies are likely to develop emphysema. Onset of emphysema often occurs before age 40 in human subjects having AAT deficiencies. Smoking can increase the risk of emphysema in subjects having AAT deficiencies. Symptoms of AAT deficiencies include shortness of breath, with and without exertion, and other symptoms commonly associated with chronic obstructive pulmonary disease (COPD). Other symptoms of AAT deficiencies include symptoms of severe liver disease (e.g., cirrhosis), unintentional weight loss, and wheezing. A physical examination may reveal a barrel-shaped chest, wheezing, or decreased breath sounds in a subject who has an AAT deficiency.
The following exemplary tests may assist with diagnosing a subject as having an AAT deficiency: an alpha-1 antitrypsin blood test, examination of arterial blood gases, a chest x-ray, a CT scan of the chest, genetic testing, and lung function test. In some cases, a subject having or suspected of having an AAT deficiency is subjected to genetic testing to detect the presence of one or more mutations in the AAT gene. In some embodiments, one or more of the mutations listed in Table 1 are detected in the subject.
In some cases, a physician may suspect that a subject has an AAT deficiency if the subject has emphysema at an early age (e.g., before the age of 45), emphysema without ever having smoked or without ever having been exposed to toxins, emphysema with a family history of an AAT deficiency, liver disease or hepatitis when no other cause can be found, liver disease or hepatitis and a family history of an AAT deficiency.
In some embodiments, alpha-1 antitrypsin deficiency can result in two distinct pathologic states: a lung disease which is primarily due to the loss of anti-protease function, and a liver disease due to a toxic gain of function of the mutant AAT protein (e.g., mutant PiZ-AAT). For example, since mutant AAT-PiZ exhibits a gain-of-function hepatocellular toxicity accumulating in the endoplasmic reticulum, therapies aimed at decreasing AAT-PiZ mRNA levels may ameliorate or even reverse the liver pathology. In addition, increased secretion of functional AAT protein protects the lungs from neutrophil elastase and associated proteolytic enzymes. Applicants have developed several rAAV vectors that provide for delivery of microRNAs targeted against mutant AAT, within the same proviral cassette as a gene encoding wild-type AAT. In some embodiments, the microRNAs are delivered using rAAV vectors that have previously been used in clinical trials.
Isolated Nucleic Acids
In general, the invention provides isolated nucleic acids, which may be rAAV vectors, useful for treating genetic disease. The isolated nucleic acids typically comprise one or more regions that encode one or more inhibitory RNAs that target an endogenous mRNA of a subject. The isolated nucleic acids also typically comprise one or more regions that encode one or more exogenous mRNAs. The protein(s) encoded by the one or more exogenous mRNAs may or may not be different in sequence composition than the protein(s) encoded by the one or more endogenous mRNAs. For example, the one or more endogenous mRNAs may encode a wild-type and mutant version of a particular protein, such as may be the case when a subject is heterozygous for a particular mutation, and the exogenous mRNA may encode a wild-type mRNA of the same particular protein. In this case, typically the sequence of the exogenous mRNA and endogenous mRNA encoding the wild-type protein are sufficiently different such that the exogenous mRNA is not targeted by the one or more inhibitory RNAs. This may be accomplished, for example, by introducing one or more silent mutations into the exogenous mRNA such that it encodes the same protein as the endogenous mRNA but has a different nucleic acid sequence. In this case, the exogenous mRNA may be referred to as “hardened.” Alternatively, the inhibitory RNA (e.g. miRNA) can target the 5′ and/or 3′ untranslated regions of the endogenous mRNA. These 5′ and/or 3′ regions can then be removed or replaced in the exogenous mRNA such that the exogenous mRNA is not targeted by the one or more inhibitory RNAs.
In another example, the one or more endogenous mRNAs may encode only mutant versions of a particular protein, such as may be the case when a subject is homozygous for a particular mutation, and the exogenous mRNA may encode a wild-type mRNA of the same particular protein. In this case, the sequence of the exogenous mRNA may be hardened as described above, or the one or more inhibitory RNAs may be designed to discriminate the mutated endogenous mRNA from the exogenous mRNA.
In some cases, the isolated nucleic acids typically comprise a first region that encodes one or more first inhibitory RNAs (e.g., miRNAs) comprising a nucleic acid having sufficient sequence complementary with an endogenous mRNA of a subject to hybridize with and inhibit expression of the endogenous mRNA, in which the endogenous mRNA encodes a first protein. The isolated nucleic acids also typically include a second region encoding an exogenous mRNA that encodes a second protein, in which the second protein has an amino acid sequence that is at least 85% identical to the first protein, in which the one or more first inhibitory RNAs do not comprise a nucleic acid having sufficient sequence complementary to hybridize with and inhibit expression of the exogenous mRNA. For example, the first region may be positioned at any suitable location. The first region may be positioned within an untranslated portion of the second region. The first region may be positioned in any untranslated portion of the nucleic acid, including, for example, an intron, a 5′ or 3′ untranslated region, etc.
In some cases, it may be desirable to position the first region upstream of the first codon of the exogenous mRNA. For example, the first region may be positioned between the first codon of the exogenous mRNA and 2000 nucleotides upstream of the first codon. The first region may be positioned between the first codon of the exogenous mRNA and 1000 nucleotides upstream of the first codon. The first region may be positioned between the first codon of the exogenous mRNA and 500 nucleotides upstream of the first codon. The first region may be positioned between the first codon of the exogenous mRNA and 250 nucleotides upstream of the first codon. The first region may be positioned between the first codon of the exogenous mRNA and 150 nucleotides upstream of the first codon.
In some cases, the first region may be positioned downstream of a portion of the second region encoding the poly-A tail of the exogenous mRNA. The first region may be between the last codon of the exogenous mRNA and a position 2000 nucleotides downstream of the last codon. The first region may be between the last codon of the exogenous mRNA and a position 1000 nucleotides downstream of the last codon. The first region may be between the last codon of the exogenous mRNA and a position 500 nucleotides downstream of the last codon. The first region may be between the last codon of the exogenous mRNA and a position 250 nucleotides downstream of the last codon. The first region may be between the last codon of the exogenous mRNA and a position 150 nucleotides downstream of the last codon.
The nucleic acid may also comprise a third region encoding a one or more second inhibitory RNAs (e.g., miRNAs) comprising a nucleic acid having sufficient sequence complementary to hybridize with and inhibit expression of the endogenous mRNA. As with the first region, the third region may be positioned at any suitable location. For example, the third region may be positioned in an untranslated portion of the second region, including, for example, an intron, a 5′ or 3′ untranslated region, etc. The third region may be positioned upstream of a portion of the second region encoding the first codon of the exogenous mRNA. The third region may be positioned downstream of a portion of the second region encoding the poly-A tail of the exogenous mRNA. In some cases, when the first region is positioned upstream of the first codon, the third region is positioned downstream of the portion of the second region encoding the poly-A tail of the exogenous mRNA, and vice versa.
In some cases, the first region and third regions encode the same set of one or more inhibitory RNAs (e.g., miRNAs). In other cases, the first region and third regions encode a different set of one or more inhibitory RNAs (e.g., miRNAs). In some cases, the one or more inhibitory RNAs (e.g., miRNAs) encoded by the first region target one or more of the same genes as the one or more inhibitory RNAs (e.g., miRNAs) encoded by the third region. In some cases, the one or more inhibitory RNAs (e.g., miRNAs) encoded by the first region do not target any of the same genes as the one or more inhibitory RNAs (e.g., miRNAs) encoded by the third region. It is to be appreciated that inhibitory RNAs (e.g., miRNAs) which target a gene have sufficient complementarity with the gene to bind to and inhibit expression (e.g., by degradation or inhibition of translation) of the corresponding mRNA.
The first and third regions may also encode a different number of inhibitory RNAs (e.g., miRNAs). For example, the first region and third regions may independently encode 1, 2, 3, 4, 5, 6 or more inhibitory RNAs (e.g., miRNAs). The first and third regions are not limited to comprising any one particular inhibitory RNA, and may include, for example, a miRNA, an shRNA, a TuD RNA, a microRNA sponge, an antisense RNA, a ribozyme, an aptamer, or other appropriate inhibitory RNA. In some cases, the first region and/or third region comprises one or more miRNAs. The one or more miRNAs may comprise a nucleic acid sequence encoded by a sequence selected from the group consisting of SEQ ID NOS: 17-19 and 21-23.
As disclosed herein, the second protein may have an amino acid sequence that is at least 85% identical to the first protein. Accordingly, the second protein may have an amino acid sequence that is at least 88%, at least 90%, at least 95%, at least 98%, at least 99% or more identical to the first protein. In some case, the second protein differs from the first protein by 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more amino acids. In some cases, one or more of the differences between the first protein and second protein are conservative amino acid substitutions. As used herein, a “conservative amino acid substitution” refers to an amino acid substitution that does not alter the relative charge or size characteristics of the protein in which the amino acid substitution is made. Variants can be prepared according to methods for altering polypeptide sequence known to one of ordinary skill in the art such as are found in references that compile such methods. Conservative substitutions of amino acids include substitutions made among amino acids within the following groups: (a) M, I, L, V; (b) F, Y, W; (c) K, R, H; (d) A, G; (e) S, T; (f) Q, N; and (g) E, D. Accordingly, conservative amino acid substitutions may provide functionally equivalent variants, or homologs of an endogenous protein.
It should be appreciated that in some cases the second protein may be a marker protein (e.g., a fluorescent protein, a fusion protein, a tagged protein, etc.). Such constructs may be useful, for example, for studying the distribution of the encoded proteins within a cell or within a subject and are also useful for evaluating the efficiency of rAAV targeting and distribution in a subject.
In some embodiments of the isolated nucleic acids, the first protein is alpha-1 antitrypsin (AAT) protein. An exemplary sequence of a wild-type AAT is provided at SEQ ID NO: 1 or 2. Accordingly, in some cases, the endogenous mRNA may comprise the RNA sequence specified by the sequence set forth in SEQ ID NO: 5. The endogenous mRNA may comprise the RNA sequence as specified by any one of the sequences set forth in SEQ ID NOS: 6-16. In some cases, the AAT protein is a human AAT protein. The AAT protein may have a sequence as set forth in SEQ ID NO: 1 or 2 or one or more mutations thereof as identified in Table 1, e.g. SEQ ID NO: 3 or 4. The exogenous mRNA may have one or more silent mutations compared with the endogenous mRNA. The exogenous mRNA may comprise the RNA sequence specified by the sequence set forth in SEQ ID NO: 20. The exogenous mRNA sequence may or may not encode a peptide tag (e.g., a myc tag, a his-tag, etc.) linked to the encoded protein. Often, in a construct used for clinical purposes, the exogenous mRNA sequence does not encode a peptide tag linked to the encoded protein.
As described further below, the isolated nucleic acids may comprise inverted terminal repeats (ITR) of an AAV serotypes selected from the group consisting of: AAV1, AAV2, AAV5, AAV6, AAV6.2, AAV7, AAV8, AAV9, AAV10, AAV11 and variants thereof. The isolated nucleic acids may also include a promoter operably linked with the one or more first inhibitory RNAs, the exogenous mRNA, and/or the one or more second inhibitory RNAs. The promoter may be tissue-specific promoter, a constitutive promoter or inducible promoter.







TABLE 1







Mutations in Human AAT - Entrez Gene ID: 5265














Chr.
mRNA
dbSNPrs#

dbSNP
Protein
Codon
Amino acid


position
position
cluster id
Function
allele
residue
position
position

















94844794
1822
rs78787657
missense
A
Lys [K]
1
417





contig reference
C
Gln [Q]
1
417


94844797
1819
rs3191200
missense
C
Pro [P]
1
416





contig reference
A
Thr [T]
1
416


94844842
1774
rs17850837
missense
A
Lys [K]
1
401





contig reference
C
Gln [Q]
1
401


94844843
1773
rs1303
missense
C
Asp [D]
3
400





contig reference
A
Glu [E]
3
400


94844855
1761
rs13170
synonymous
T
Phe [F]
3
396





contig reference
C
Phe [F]
3
396


94844866
1750
rs61761869
missense
T
Ser [S]
1
393





contig reference
C
Pro [P]
1
393


94844887
1729
rs12233
missense
T
Ser [S]
1
386





contig reference
C
Pro [P]
1
386


94844912
1704
rs28929473
missense
T
Phe [F]
3
377





contig reference
A
Leu [L]
3
377


94844926
1690
rs12077
missense
T
Trp [W]
1
373





contig reference
G
Gly [G]
1
373


94844942
1674
rs1050520
synonymous
G
Lys [K]
3
367





contig reference
A
Lys [K]
3
367


94844947
1669
rs28929474
missense
A
Lys [K]
1
366





contig reference
G
Glu [E]
1
366


94844954
1662
rs1050469
synonymous
G
Thr [T]
3
363





contig reference
C
Thr [T]
3
363


94844957
1659
rs1802961
synonymous
T
Leu [L]
3
362





contig reference
G
Leu [L]
3
362


94844959
1657
rs1131154
missense
A
Met [M]
1
362





contig reference
C
Leu [L]
1
362


94844960
1656
rs13868
synonymous
A
Val [V]
3
361





contig reference
G
Val [V]
3
361


94844961
1655
rs1131139
missense
C
Ala [A]
2
361





contig reference
T
Val [V]
2
361


94844962
1654
rs72555357
frame shift


1
361





contig reference
G
Val [V]
1
361


94844965
1651
rs1802959
missense
A
Thr [T]
1
360





contig reference
G
Ala [A]
1
360


94844972
1644
rs10427
synonymous
C
Val [V]
3
357





contig reference
G
Val [V]
3
357


94844975
1641
rs9630
synonymous
T
Ala [A]
3
356





contig reference
C
Ala [A]
3
356


94844977
1639
rs67216923
frame shift


1
356





frame shift
(15bp)

1
356





contig reference
G
Ala [A]
1
356


94845814
1625
rs72555374
frame shift


2
351





contig reference
T
Leu [L]
2
351


94845845
1594
rs28929471
missense
A
Asn [N]
1
341





contig reference
G
Asp [D]
1
341


94845893
1546
rs1802962
missense
T
Cys [C]
1
325





contig reference
A
Ser [S]
1
325


94845902
1537
rs55704149
missense
T
Tyr [Y]
1
322





contig reference
G
Asp [D]
1
322


94845914
1525
rs117001071
missense
T
Ser [S]
1
318





contig reference
A
Thr [T]
1
318


94845917
1521
rs35624994
frame shift

Ser [S]
3
316





frame shift
C
Ser [S]
3
316





contig reference
CA
Ser [S]
3
316


94847218
1480
rs1802963
nonsense
T
xxx [X]
1
303





contig reference
G
Glu [E]
1
303


94847262
1436
rs17580
missense
T
Val [V]
2
288





contig reference
A
Glu [E]
2
288


94847285
1413
rs1049800
synonymous
C
Asp [D]
3
280





contig reference
T
Asp [D]
3
280


94847306
1392
rs2230075
synonymous
T
Thr [T]
3
273





contig reference
C
Thr [T]
3
273


94847351
1347
rs34112109
synonymous
A
Lys [K]
3
258





contig reference
G
Lys [K]
3
258


94847357
1341
rs8350
missense
G
Trp [W]
3
256





contig reference
T
Cys [C]
3
256


94847386
1312
rs28929470
missense
T
Cys [C]
1
247





contig reference
C
Arg [R]
1
247


94847407
1291
rs72552401
missense
A
Met [M]
1
240





contig reference
G
Val [V]
1
240


94847415
1283
rs6647
missense
C
Ala [A]
2
237





contig reference
T
Val [V]
2
237


94847452
1246
rs11558264
missense
C
Gln [Q]
1
225





contig reference
A
Lys [K]
1
225


94847466
1232
rs11558257
missense
T
Ile [I]
2
220





contig reference
G
Arg [R]
2
220


94847475
1223
rs11558265
missense
C
Thr [T]
2
217





contig reference
A
Lys [K]
2
217


94849029
1119
rs113813309
synonymous
T
Asn [N]
3
182





contig reference
C
Asn [N]
3
182


94849053
1095
rs72552402
synonymous
T
Thr [T]
3
174





contig reference
C
Thr [T]
3
174


94849061
1087
rs112030253
missense
A
Arg [R]
1
172





contig reference
G
Gly [G]
1
172


94849109
1039
rs78640395
nonsense
T
xxx [X]
1
156





contig reference
G
Glu [E]
1
156


94849140
1008
rs11558263
missense
A
Arg [R]
3
145





contig reference
C
Ser [S]
3
145


94849151
997
rs20546
synonymous
T
Leu [L]
1
142





contig reference
C
Leu [L]
1
142


94849160
988
rs11558261
missense
A
Ser [S]
1
139





contig reference
G
Gly [G]
1
139


94849201
947
rs709932
missense
A
His [H]
2
125





contig reference
G
Arg [R]
2
125


94849228
920
rs28931572
missense
A
Asn [N]
2
116





contig reference
T
Ile [I]
2
116


94849303
845
rs28931568
missense
A
Glu [E]
2
91





contig reference
G
Gly [G]
2
91


94849325
823
rs111850950
missense
A
Thr [T]
1
84





contig reference
G
Ala [A]
1
84


94849331
817
rs113817720
missense
A
Thr [T]
1
82





contig reference
G
Ala [A]
1
82


94849345
803
rs55819880
missense
T
Phe [F]
2
77





contig reference
C
Ser [S]
2
77


94849364
784
rs11575873
missense
C
Arg [R]
1
71





contig reference
A
Ser [S]
1
71


94849381
767
rs28931569
missense
C
Pro [P]
2
65





contig reference
T
Leu [L]
2
65


94849388
760
rs28931570
missense
T
Cys [C]
1
63





contig reference
C
Arg [R]
1
63


94849466
682
rs11558262
missense
G
Ala [A]
1
37





contig reference
A
Thr [T]
1
37


94849492
656
rs11558259
missense
G
Arg [R]
2
28





contig reference
A
Gln [Q]
2
28


94849548
600
rs11558260
synonymous
T
Ile [I]
3
9





contig reference
C
Ile [I]
3
9





start codon



1









Methods of Use

The invention also provides methods for expressing alpha 1-antitrypsin (AAT) protein in a subject. Typically, the subject has or suspected of having an AAT deficiency. The methods typically involve administering to a subject an effective amount of a recombinant Adeno-Associated Virus (rAAV) harboring any of the isolated nucleic acids disclosed herein. In general, the “effective amount” of a rAAV refers to an amount sufficient to elicit the desired biological response. In some embodiments, the effective amount refers to the amount of rAAV effective for transducing a cell or tissue ex vivo. In other embodiments, the effective amount refers to the amount effective for direct administration of rAAV to a subject. As will be appreciated by those of ordinary skill in this art, the effective amount of the recombinant AAV of the invention varies depending on such factors as the desired biological endpoint, the pharmacokinetics of the expression products, the condition being treated, the mode of administration, and the subject. Typically, the rAAV is administered with a pharmaceutically acceptable carrier.
The subject may have a mutation in an AAT gene. The mutation may result in decreased expression of wild-type (normal) AAT protein. The subject may be homozygous for the mutation. The subject may be heterozygous for the mutation. The mutation may be a missense mutation. The mutation may be a nonsense mutation. The mutation may be a mutation listed in Table 1. The mutation may result in expression of a mutant AAT protein. The mutant protein may be a gain-of-function mutant or a loss-of-function mutant. The mutant AAT protein may be incapable of inhibiting protease activity. The mutant AAT protein may fail to fold properly. The mutant AAT protein may result in the formation of protein aggregates. The mutant AAT protein may result in the formation of intracellular AAT globules. The mutation may result in a glutamate to lysine substitution at amino acid position 366 in the precursor protein according to the amino acid sequence set forth as SEQ ID NO: 3. In the mature protein, this same mutation occurs at amino acid position 342 (SEQ ID NO: 4). The methods may also involve determining whether the subject has a mutation. Accordingly the methods may involve obtaining a genotype of the AAT gene in the subject.
In some cases, after administration of the rAAV the level of expression of the first protein and/or second protein is determined in the subject. The administration may be performed on one or more occasions. When the administration is performed on one or more occasions, the level of the first protein and/or the level of the second protein in the subject are often determined after at least one administration. In some cases, the serum level of the first protein in the subject is reduced by at least 85% following administration of the rAAV. The serum level of the first protein in the subject may be reduced by at least 90% following administration of the rAAV. The serum level of the first protein in the subject may be reduced by at least 95% following administration of the rAAV. However, in some cases, the serum level of the first protein in the subject is reduced by at least 40%, at least 50%, at least 60%, at least 70%, or at least 80% following administration of the rAAV.
The level (e.g., serum level) of the first protein in the subject may be reduced by at least 85% within 2 weeks following administration of the rAAV. The serum level of the first protein in the subject may be reduced by at least 90% within 2 weeks following administration of the rAAV. The serum level of the first protein in the subject may be reduced by at least 85% within 4 weeks of administration of the rAAV. The reduction may be observed within 1 day, within 2 days, within 3 days, within 4 days, within 5 days, within 6 days, within 1 week, within 2 weeks, within 3 weeks, within 4 weeks or more.
The reduction in the level of the first protein may be sustained for at least 1 week, at least 2 weeks, at least 3 weeks, at least 4 weeks, at least 5 weeks, at least 6 weeks, at least 7 weeks, at least 8 weeks, at least 9 weeks, at least 10 weeks, at least 11 weeks, or more. In some cases, after 7 weeks of administration of the rAAV, the serum level of the first protein is at a level of at least 50% compared with the serum level of the first protein prior to administration of the rAAV. In certain cases, after 7 weeks of administration of the rAAV, the serum level of the first protein is at a level of at least 75% compared with the serum level of the first protein prior to administration of the rAAV.
In some instances, after administration of the rAAV at least one clinical outcome parameter associated with the AAT deficiency is evaluated in the subject. Typically, the clinical outcome parameter evaluated after administration of the rAAV is compared with the clinical outcome parameter determined at a time prior to administration of the rAAV to determine effectiveness of the rAAV. Often an improvement in the clinical outcome parameter after administration of the rAAV indicates effectiveness of the rAAV. Any appropriate clinical outcome parameter may be used. Typically, the clinical outcome parameter is indicative of the one or more symptoms of an AAT deficiency. For example, the clinical outcome parameter may be selected from the group consisting of: serum levels of the first protein, serum levels of the second protein, presence of intracellular AAT globules, presence of inflammatory foci, breathing capacity, cough frequency, phlegm production, frequency of chest colds or pneumonia, and tolerance for exercise. Intracellular AAT globules or inflammatory foci are evaluated in tissues affected by the AAT deficiency, including, for example, lung tissue or liver tissue.
Recombinant AAVs
In some aspects, the invention provides isolated AAVs. As used herein with respect to AAVs, the term “isolated” refers to an AAV that has been isolated from its natural environment (e.g., from a host cell, tissue, or subject) or artificially produced. Isolated AAVs may be produced using recombinant methods. Such AAVs are referred to herein as “recombinant AAVs”. Recombinant AAVs (rAAVs) preferably have tissue-specific targeting capabilities, such that a transgene of the rAAV will be delivered specifically to one or more predetermined tissue(s). The AAV capsid is an important element in determining these tissue-specific targeting capabilities. Thus, a rAAV having a capsid appropriate for the tissue being targeted can be selected. In some embodiments, the rAAV comprises a capsid protein having an amino acid sequence corresponding to any one of AAV1, AAV2, AAV3, AAV4, AAV5, AAV6, AAV7, AAV8, AAV9, AAV10, AAV11 and variants thereof. The recombinant AAVs typically harbor an isolated nucleic acid of the invention.
Methods for obtaining recombinant AAVs having a desired capsid protein are well known in the art (See, for example, US 2003/0138772, the contents of which are incorporated herein by reference in their entirety). AAV capsid proteins that may be used in the rAAVs of the invention a include, for example, those disclosed in G. Gao, et al., J. Virol, 78(12):6381-6388 (June 2004); G. Gao, et al, Proc Natl Acad Sci USA, 100(10):6081-6086 (May 13, 2003); US 2003-0138772, US 2007/0036760, US 2009/0197338, and WO 2010/138263, the contents of which relating to AAVs capsid proteins and associated nucleotide and amino acid sequences are incorporated herein by reference. Typically the methods involve culturing a host cell which contains a nucleic acid sequence encoding an AAV capsid protein or fragment thereof; a functional rep gene; a recombinant AAV vector composed of AAV inverted terminal repeats (ITRs) and a transgene; and sufficient helper functions to permit packaging of the recombinant AAV vector into the AAV capsid proteins.
The components to be cultured in the host cell to package a rAAV vector in an AAV capsid may be provided to the host cell in trans. Alternatively, any one or more of the required components (e.g., recombinant AAV vector, rep sequences, cap sequences, and/or helper functions) may be provided by a stable host cell which has been engineered to contain one or more of the required components using methods known to those of skill in the art. Most suitably, such a stable host cell will contain the required component(s) under the control of an inducible promoter. However, the required component(s) may be under the control of a constitutive promoter. Examples of suitable inducible and constitutive promoters are provided herein. In still another alternative, a selected stable host cell may contain selected component(s) under the control of a constitutive promoter and other selected component(s) under the control of one or more inducible promoters. For example, a stable host cell may be generated which is derived from 293 cells (which contain E1 helper functions under the control of a constitutive promoter), but which contain the rep and/or cap proteins under the control of inducible promoters. Still other stable host cells may be generated by one of skill in the art.
The recombinant AAV vector, rep sequences, cap sequences, and helper functions required for producing the rAAV of the invention may be delivered to the packaging host cell using any appropriate genetic element (vector). The selected genetic element may be delivered by any suitable method, including those described herein. The methods used to construct any embodiment of this invention are known to those with skill in nucleic acid manipulation and include genetic engineering, recombinant engineering, and synthetic techniques. See, e.g., Sambrook et al, Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Press, Cold Spring Harbor, N.Y. Similarly, methods of generating rAAV virions are well known and the selection of a suitable method is not a limitation on the present invention. See, e.g., K. Fisher et al, J. Virol., 70:520-532 (1993) and U.S. Pat. No. 5,478,745.
In some embodiments, recombinant AAVs may be produced using the triple transfection method (e.g., as described in detail in U.S. Pat. No. 6,001,650, the contents of which relating to the triple transfection method are incorporated herein by reference). Typically, the recombinant AAVs are produced by transfecting a host cell with a recombinant AAV vector (comprising a transgene) to be packaged into AAV particles, an AAV helper function vector, and an accessory function vector. An AAV helper function vector encodes the “AAV helper function” sequences (i.e., rep and cap), which function in trans for productive AAV replication and encapsidation. Preferably, the AAV helper function vector supports efficient AAV vector production without generating any detectable wild-type AAV virions (i.e., AAV virions containing functional rep and cap genes). Non-limiting examples of vectors suitable for use with the present invention include pHLP19, described in U.S. Pat. No. 6,001,650 and pRep6cap6 vector, described in U.S. Pat. No. 6,156,303, the entirety of both incorporated by reference herein. The accessory function vector encodes nucleotide sequences for non-AAV derived viral and/or cellular functions upon which AAV is dependent for replication (i.e., “accessory functions”). The accessory functions include those functions required for AAV replication, including, without limitation, those moieties involved in activation of AAV gene transcription, stage specific AAV mRNA splicing, AAV DNA replication, synthesis of cap expression products, and AAV capsid assembly. Viral-based accessory functions can be derived from any of the known helper viruses such as adenovirus, herpesvirus (other than herpes simplex virus type-1), and vaccinia virus.
In some aspects, the invention provides transfected host cells. The term “transfection” is used to refer to the uptake of foreign DNA by a cell, and a cell has been “transfected” when exogenous DNA has been introduced inside the cell membrane. A number of transfection techniques are generally known in the art. See, e.g., Graham et al. (1973) Virology, 52:456, Sambrook et al. (1989) Molecular Cloning, a laboratory manual, Cold Spring Harbor Laboratories, New York, Davis et al. (1986) Basic Methods in Molecular Biology, Elsevier, and Chu et al. (1981) Gene 13:197. Such techniques can be used to introduce one or more exogenous nucleic acids, such as a nucleotide integration vector and other nucleic acid molecules, into suitable host cells.
A “host cell” refers to any cell that harbors, or is capable of harboring, a substance of interest. Often a host cell is a mammalian cell. A host cell may be used as a recipient of an AAV helper construct, an AAV minigene plasmid, an accessory function vector, or other transfer DNA associated with the production of recombinant AAVs. The term includes the progeny of the original cell which has been transfected. Thus, a “host cell” as used herein may refer to a cell which has been transfected with an exogenous DNA sequence. It is understood that the progeny of a single parental cell may not necessarily be completely identical in morphology or in genomic or total DNA complement as the original parent, due to natural, accidental, or deliberate mutation.
In some aspects, the invention provides isolated cells. As used herein with respect to cell, the term “isolated” refers to a cell that has been isolated from its natural environment (e.g., from a tissue or subject). As used herein, the term “cell line” refers to a population of cells capable of continuous or prolonged growth and division in vitro. Often, cell lines are clonal populations derived from a single progenitor cell. It is further known in the art that spontaneous or induced changes can occur in karyotype during storage or transfer of such clonal populations. Therefore, cells derived from the cell line referred to may not be precisely identical to the ancestral cells or cultures, and the cell line referred to includes such variants. As used herein, the terms “recombinant cell” refers to a cell into which an exogenous DNA segment, such as DNA segment that leads to the transcription of a biologically-active polypeptide or production of a biologically active nucleic acid such as an RNA, has been introduced.
As used herein, the term “vector” includes any genetic element, such as a plasmid, phage, transposon, cosmid, chromosome, artificial chromosome, virus, virion, etc., which is capable of replication when associated with the proper control elements and which can transfer gene sequences between cells. Thus, the term includes cloning and expression vehicles, as well as viral vectors. In some embodiments, useful vectors are contemplated to be those vectors in which the nucleic acid segment to be transcribed is positioned under the transcriptional control of a promoter. A “promoter” refers to a DNA sequence recognized by the synthetic machinery of the cell, or introduced synthetic machinery, required to initiate the specific transcription of a gene. The phrases “operatively positioned,” “under control” or “under transcriptional control” means that the promoter is in the correct location and orientation in relation to the nucleic acid to control RNA polymerase initiation and expression of the gene. The term “expression vector or construct” means any type of genetic construct containing a nucleic acid in which part or all of the nucleic acid encoding sequence is capable of being transcribed. In some embodiments, expression includes transcription of the nucleic acid, for example, to generate a biologically-active polypeptide product or inhibitory RNA (e.g., shRNA, miRNA) from a transcribed gene.
The foregoing methods for packaging recombinant vectors in desired AAV capsids to produce the rAAVs of the invention are not meant to be limiting and other suitable methods will be apparent to the skilled artisan.
Recombinant AAV Vectors
The isolated nucleic acids of the invention may be recombinant AAV vectors. The recombinant AAV vector may be packaged into a capsid protein and administered to a subject and/or delivered to a selected target cell. “Recombinant AAV (rAAV) vectors” are typically composed of, at a minimum, a transgene and its regulatory sequences, and 5′ and 3′ AAV inverted terminal repeats (ITRs). The transgene may comprise, as disclosed elsewhere herein, one or more regions that encode one or more inhibitory RNAs (e.g., miRNAs) comprising a nucleic acid that targets an endogenous mRNA of a subject. The transgene may also comprise a region encoding an exogenous mRNA that encodes a protein (e.g., a protein that has an amino acid sequence that is at least 85% identical to the protein encoded by the endogenous mRNA), in which the one or more inhibitory RNAs do not target the exogenous mRNA.
The AAV sequences of the vector typically comprise the cis-acting 5′ and 3′ inverted terminal repeat sequences (See, e.g., B. J. Carter, in “Handbook of Parvoviruses”, ed., P. Tijsser, CRC Press, pp. 155 168 (1990)). The ITR sequences are about 145 by in length. Preferably, substantially the entire sequences encoding the ITRs are used in the molecule, although some degree of minor modification of these sequences is permissible. The ability to modify these ITR sequences is within the skill of the art. (See, e.g., texts such as Sambrook et al, “Molecular Cloning. A Laboratory Manual”, 2d ed., Cold Spring Harbor Laboratory, New York (1989); and K. Fisher et al., J Virol., 70:520 532 (1996)). An example of such a molecule employed in the present invention is a “cis-acting” plasmid containing the transgene, in which the selected transgene sequence and associated regulatory elements are flanked by the 5′ and 3′ AAV ITR sequences. The AAV ITR sequences may be obtained from any known AAV, including presently identified mammalian AAV types.
In addition to the major elements identified above for the recombinant AAV vector, the vector also includes conventional control elements which are operably linked with elements of the transgene in a manner that permits its transcription, translation and/or expression in a cell transfected with the vector or infected with the virus produced by the invention. As used herein, “operably linked” sequences include both expression control sequences that are contiguous with the gene of interest and expression control sequences that act in trans or at a distance to control the gene of interest. Expression control sequences include appropriate transcription initiation, termination, promoter and enhancer sequences; efficient RNA processing signals such as splicing and polyadenylation (polyA) signals; sequences that stabilize cytoplasmic mRNA; sequences that enhance translation efficiency (i.e., Kozak consensus sequence); sequences that enhance protein stability; and when desired, sequences that enhance secretion of the encoded product. A number of expression control sequences, including promoters which are native, constitutive, inducible and/or tissue-specific, are known in the art and may be utilized.
As used herein, a nucleic acid sequence (e.g., coding sequence) and regulatory sequences are said to be operably linked when they are covalently linked in such a way as to place the expression or transcription of the nucleic acid sequence under the influence or control of the regulatory sequences. If it is desired that the nucleic acid sequences be translated into a functional protein, two DNA sequences are said to be operably linked if induction of a promoter in the 5′ regulatory sequences results in the transcription of the coding sequence and if the nature of the linkage between the two DNA sequences does not (1) result in the introduction of a frame-shift mutation, (2) interfere with the ability of the promoter region to direct the transcription of the coding sequences, or (3) interfere with the ability of the corresponding RNA transcript to be translated into a protein. Thus, a promoter region would be operably linked to a nucleic acid sequence if the promoter region were capable of effecting transcription of that DNA sequence such that the resulting transcript might be translated into the desired protein or polypeptide. Similarly two or more coding regions are operably linked when they are linked in such a way that their transcription from a common promoter results in the expression of two or more proteins having been translated in frame. In some embodiments, operably linked coding sequences yield a fusion protein. In some embodiments, operably linked coding sequences yield a functional RNA (e.g., miRNA).
For nucleic acids encoding proteins, a polyadenylation sequence generally is inserted following the transgene sequences and before the 3′ AAV ITR sequence. A rAAV construct useful in the present invention may also contain an intron, desirably located between the promoter/enhancer sequence and the transgene. One possible intron sequence is derived from SV-40, and is referred to as the SV-40 T intron sequence. Any intron may be from the β-Actin gene. Another vector element that may be used is an internal ribosome entry site (IRES).
The precise nature of the regulatory sequences needed for gene expression in host cells may vary between species, tissues or cell types, but shall in general include, as necessary, 5′ non-transcribed and 5′ non-translated sequences involved with the initiation of transcription and translation respectively, such as a TATA box, capping sequence, CAAT sequence, enhancer elements, and the like. Especially, such 5′ non-transcribed regulatory sequences will include a promoter region that includes a promoter sequence for transcriptional control of the operably joined gene. Regulatory sequences may also include enhancer sequences or upstream activator sequences as desired. The vectors of the invention may optionally include 5′ leader or signal sequences. The choice and design of an appropriate vector is within the ability and discretion of one of ordinary skill in the art.
Examples of constitutive promoters include, without limitation, the retroviral Rous sarcoma virus (RSV) LTR promoter (optionally with the RSV enhancer), the cytomegalovirus (CMV) promoter (optionally with the CMV enhancer), the SV40 promoter, and the dihydrofolate reductase promoter. Inducible promoters allow regulation of gene expression and can be regulated by exogenously supplied compounds, environmental factors such as temperature, or the presence of a specific physiological state, e.g., acute phase, a particular differentiation state of the cell, or in replicating cells only. Inducible promoters and inducible systems are available from a variety of commercial sources, including, without limitation, Invitrogen, Clontech and Ariad. Many other systems have been described and can be readily selected by one of skill in the art. Examples of inducible promoters regulated by exogenously supplied promoters include the zinc-inducible sheep metallothionine (MT) promoter, the dexamethasone (Dex)-inducible mouse mammary tumor virus (MMTV) promoter, the T7 polymerase promoter system, the ecdysone insect promoter, the tetracycline-repressible system, the tetracycline-inducible system, the RU486-inducible system and the rapamycin-inducible system. Still other types of inducible promoters which may be useful in this context are those which are regulated by a specific physiological state, e.g., temperature, acute phase, a particular differentiation state of the cell, or in replicating cells only. In another embodiment, the native promoter, or fragment thereof, for the transgene will be used. In a further embodiment, other native expression control elements, such as enhancer elements, polyadenylation sites or Kozak consensus sequences may also be used to mimic the native expression.
In some embodiments, the regulatory sequences impart tissue-specific gene expression capabilities. In some cases, the tissue-specific regulatory sequences bind tissue-specific transcription factors that induce transcription in a tissue specific manner. Such tissue-specific regulatory sequences (e.g., promoters, enhancers, etc.) are well known in the art. In some embodiments, the promoter is a chicken β-actin promoter.
In some embodiments, one or more bindings sites for one or more of miRNAs are incorporated in a transgene of a rAAV vector, to inhibit the expression of the transgene in one or more tissues of a subject harboring the transgenes, e.g., non-liver tissues, non-lung tissues. The skilled artisan will appreciate that binding sites may be selected to control the expression of a transgene in a tissue specific manner. The miRNA target sites in the mRNA may be in the 5′ UTR, the 3′ UTR or in the coding region. Typically, the target site is in the 3′ UTR of the mRNA. Furthermore, the transgene may be designed such that multiple miRNAs regulate the mRNA by recognizing the same or multiple sites. The presence of multiple miRNA binding sites may result in the cooperative action of multiple RISCs and provide highly efficient inhibition of expression. The target site sequence may comprise a total of 5-100, 10-60, or more nucleotides. The target site sequence may comprise at least 5 nucleotides of the sequence of a target gene binding site.
In some embodiments, the cloning capacity of the recombinant RNA vector may be limited and a desired coding sequence may involve the complete replacement of the virus's 4.8 kilobase genome. Large genes may, therefore, not be suitable for use in a standard recombinant AAV vector, in some cases. The skilled artisan will appreciate that options are available in the art for overcoming a limited coding capacity. For example, the AAV ITRs of two genomes can anneal to form head to tail concatamers, almost doubling the capacity of the vector. Insertion of splice sites allows for the removal of the ITRs from the transcript. Other options for overcoming a limited cloning capacity will be apparent to the skilled artisan.
Recombinant AAV Administration
rAAVs are administered in sufficient amounts to transfect the cells of a desired tissue and to provide sufficient levels of gene transfer and expression without undue adverse effects. Conventional and pharmaceutically acceptable routes of administration include, but are not limited to, direct delivery to the selected tissue (e.g., liver tissue, lung tissue) and administration subcutaneously, intraopancreatically, intranasally, parenterally, intravenously, intramuscularly, intrathecally, intracerebrally, orally, intraperitoneally, by inhalation or by another route. Routes of administration may be combined, if desired. Delivery of certain rAAVs to a subject may be, for example, by administration into the bloodstream of the subject. Administration into the bloodstream may be by injection into a vein, an artery, or any other vascular conduit.
In certain circumstances it will be desirable to deliver the rAAV-based therapeutic constructs in suitably formulated pharmaceutical compositions disclosed herein either subcutaneously, intraopancreatically, intranasally, parenterally, intravenously, intramuscularly, intrathecally, intracerebrally, orally, intraperitoneally, or by inhalation.
It can be appreciated by one skilled in the art that desirable administration of rAAV-based therapeutic constructs can also include ex vivo administration. In some embodiments, ex vivo administration comprises (1) isolation of cells or tissue(s) of interest from a subject, (2) contacting the cells or tissue(s) with rAAVs in sufficient amounts to transfect the cells or tissue to provide sufficient levels of gene transfer and expression without undue adverse effect, and (3) transferring cells or tissue back into the subject. In some embodiments, cells or tissues may be cultured ex vivo for several days before and/or after transfection.
Cells or tissues can be isolated from a subject by any suitable method. For example, cells or tissues may be isolated by surgery, biopsy (e.g., biopsy of skin tissue, lung tissue, liver tissue, adipose tissue), or collection of biological fluids such as blood. In some embodiments, cells are isolated from bone marrow. In some embodiments, cells are isolated from adipose tissue. In some embodiments, cells are isolated from a lipoaspirate. Appropriate methods for isolating cells from adipose tissue for ex vivo transfection are known in the art. See, e.g., Kuroda, M., et al., (2011), Journal of Diabetes Investigation, 2: 333-340; Kouki Morizono, et al. Human Gene Therapy. January 2003, 14(1): 59-66; and Patricia A. Zuk, Viral Transduction of Adipose-Derived Stem Cells, Methods in Molecular Biology, 1, Volume 702, Adipose-Derived Stem Cells, Part 4, Pages 345-357.
In some embodiments, the isolated cells comprise stem cells, pluripotent stem cells, lipoaspirate derived stem cells, liver cells (e.g., hepatocytes), hematopeotic stem cells, mesenchymal stem cells, stromal cells, hematopeotic cells, blood cells, fibroblasts, endothelial cells, epithelial cells, or other suitable cells. In some embodiments, cells to be transfected are induced pluripotent stem cells prepared from cells isolated from the subject.
In an embodiment, cells or tissue(s) are transduced at a multiplicity of infection (MOI) of at least 10 infectious units (i.u.) of a rAAV per cell (for example, 10, 100, 1,000, 5,000, 10,000, 100,000 or more i.u.) or at a functionally equivalent viral copy number. In one embodiment, cells or tissue(s) are transduced at a MOI of 10 to 10,000 i.u. Routes for transfer of transfected cells or tissue(s) into a subject include, but are not limited to, subcutaneously, intraopancreatically, intranasally, parenterally, intravenously, intravascularly, intramuscularly, intrathecally, intracerebrally, intraperitoneally, or by inhalation. In some embodiments, transfected cells are administered by hepatic portal vein injection. In some embodiments, transfected cells are administered intravascularly. Methods for ex vivo administration of rAAV are well known in the art (see, e.g., Naldini, L. Nature Reviews Genetics (2011) 12, 301-315, Li, H. et al. Molecular Therapy (2010) 18, 1553-1558, and Loiler et al. Gene Therapy (2003) 10, 1551-1558).
Recombinant AAV Compositions
The rAAVs may be delivered to a subject in compositions according to any appropriate methods known in the art. The rAAV, preferably suspended in a physiologically compatible carrier (e.g., in a composition), may be administered to a subject, e.g., a human, mouse, rat, cat, dog, sheep, rabbit, horse, cow, goat, pig, guinea pig, hamster, chicken, turkey, or a non-human primate (e.g., Macaque). The compositions of the invention may comprise a rAAV alone, or in combination with one or more other viruses (e.g., a second rAAV encoding having one or more different transgenes).
Suitable carriers may be readily selected by one of skill in the art in view of the indication for which the rAAV is directed. For example, one suitable carrier includes saline, which may be formulated with a variety of buffering solutions (e.g., phosphate buffered saline). Other exemplary carriers include sterile saline, lactose, sucrose, calcium phosphate, gelatin, dextran, agar, pectin, peanut oil, sesame oil, and water. Still others will be apparent to the skilled artisan.
Optionally, the compositions of the invention may contain, in addition to the rAAV and carrier(s), other conventional pharmaceutical ingredients, such as preservatives, or chemical stabilizers. Suitable exemplary preservatives include chlorobutanol, potassium sorbate, sorbic acid, sulfur dioxide, propyl gallate, the parabens, ethyl vanillin, glycerin, phenol, and parachlorophenol. Suitable chemical stabilizers include gelatin and albumin.
The dose of rAAV virions required to achieve a desired effect or “therapeutic effect,” e.g., the units of dose in vector genomes/per kilogram of body weight (vg/kg), will vary based on several factors including, but not limited to: the route of rAAV administration, the level of gene or RNA expression required to achieve a therapeutic effect, the specific disease or disorder being treated, and the stability of the gene or RNA product. One of skill in the art can readily determine a rAAV virion dose range to treat a subject having a particular disease or disorder based on the aforementioned factors, as well as other factors that are well known in the art. An effective amount of the rAAV is generally in the range of from about 10 μl to about 100 ml of solution containing from about 109 to 1016 genome copies per subject. Other volumes of solution may be used. The volume used will typically depend, among other things, on the size of the subject, the dose of the rAAV, and the route of administration. For example, for intravenous administration a volume in range of 10 μl to 100 μl, 100 μl to 1 ml, 1 ml to 10 ml, or more may be used. In some cases, a dosage between about 1010 to 1012 rAAV genome copies per subject is appropriate. In some embodiments the rAAV is administered at a dose of 1010, 1011, 1012, 1013, 1014, or 1015 genome copies per subject. In some embodiments the rAAV is administered at a dose of 1010, 1011, 1012, 1013, or 1014 genome copies per kg.
In some embodiments, rAAV compositions are formulated to reduce aggregation of AAV particles in the composition, particularly where high rAAV concentrations are present (e.g.,  ̃1013 GC/ml or more). Methods for reducing aggregation of rAAVs are well known in the art and, include, for example, addition of surfactants, pH adjustment, salt concentration adjustment, etc. (See, e.g., Wright F R, et al., Molecular Therapy (2005) 12, 171-178, the contents of which are incorporated herein by reference.)
Formulation of pharmaceutically-acceptable excipients and carrier solutions is well-known to those of skill in the art, as is the development of suitable dosing and treatment regimens for using the particular compositions described herein in a variety of treatment regimens. Typically, these formulations may contain at least about 0.1% of the active ingredient or more, although the percentage of the active ingredient(s) may, of course, be varied and may conveniently be between about 1 or 2% and about 70% or 80% or more of the weight or volume of the total formulation. Naturally, the amount of active ingredient in each therapeutically-useful composition may be prepared is such a way that a suitable dosage will be obtained in any given unit dose of the compound. Factors such as solubility, bioavailability, biological half-life, route of administration, product shelf life, as well as other pharmacological considerations will be contemplated by one skilled in the art of preparing such pharmaceutical formulations, and as such, a variety of dosages and treatment regimens may be desirable.
The pharmaceutical forms suitable for injectable use include sterile aqueous solutions or dispersions and sterile powders for the extemporaneous preparation of sterile injectable solutions or dispersions. Dispersions may also be prepared in glycerol, liquid polyethylene glycols, and mixtures thereof and in oils. Under ordinary conditions of storage and use, these preparations contain a preservative to prevent the growth of microorganisms. In many cases the form is sterile and fluid to the extent that easy syringability exists. It must be stable under the conditions of manufacture and storage and must be preserved against the contaminating action of microorganisms, such as bacteria and fungi. The carrier can be a solvent or dispersion medium containing, for example, water, ethanol, polyol (e.g., glycerol, propylene glycol, and liquid polyethylene glycol, and the like), suitable mixtures thereof, and/or vegetable oils. Proper fluidity may be maintained, for example, by the use of a coating, such as lecithin, by the maintenance of the required particle size in the case of dispersion and by the use of surfactants. The prevention of the action of microorganisms can be brought about by various antibacterial and antifungal agents, for example, parabens, chlorobutanol, phenol, sorbic acid, thimerosal, and the like. In many cases, it will be preferable to include isotonic agents, for example, sugars or sodium chloride. Prolonged absorption of the injectable compositions can be brought about by the use in the compositions of agents delaying absorption, for example, aluminum monostearate and gelatin.
For administration of an injectable aqueous solution, for example, the solution may be suitably buffered, if necessary, and the liquid diluent first rendered isotonic with sufficient saline or glucose. These particular aqueous solutions are especially suitable for intravenous, intramuscular, subcutaneous and intraperitoneal administration. In this connection, a sterile aqueous medium that can be employed will be known to those of skill in the art. For example, one dosage may be dissolved in 1 ml of isotonic NaCl solution and either added to 1000 ml of hypodermoclysis fluid or injected at the proposed site of infusion, (see for example, “Remington's Pharmaceutical Sciences” 15th Edition, pages 1035-1038 and 1570-1580). Some variation in dosage will necessarily occur depending on the condition of the host. The person responsible for administration will, in any event, determine the appropriate dose for the individual host.
Sterile injectable solutions are prepared by incorporating the active rAAV in the required amount in the appropriate solvent with various of the other ingredients enumerated herein, as required, followed by filtered sterilization. Generally, dispersions are prepared by incorporating the various sterilized active ingredients into a sterile vehicle which contains the basic dispersion medium and the required other ingredients from those enumerated above. In the case of sterile powders for the preparation of sterile injectable solutions, the preferred methods of preparation are vacuum-drying and freeze-drying techniques which yield a powder of the active ingredient plus any additional desired ingredient from a previously sterile-filtered solution thereof.
The rAAV compositions disclosed herein may also be formulated in a neutral or salt form. Pharmaceutically-acceptable salts, include the acid addition salts (formed with the free amino groups of the protein) and which are formed with inorganic acids such as, for example, hydrochloric or phosphoric acids, or such organic acids as acetic, oxalic, tartaric, mandelic, and the like. Salts formed with the free carboxyl groups can also be derived from inorganic bases such as, for example, sodium, potassium, ammonium, calcium, or ferric hydroxides, and such organic bases as isopropylamine, trimethylamine, histidine, procaine and the like. Upon formulation, solutions will be administered in a manner compatible with the dosage formulation and in such amount as is therapeutically effective. The formulations are easily administered in a variety of dosage forms such as injectable solutions, drug-release capsules, and the like.
As used herein, “carrier” includes any and all solvents, dispersion media, vehicles, coatings, diluents, antibacterial and antifungal agents, isotonic and absorption delaying agents, buffers, carrier solutions, suspensions, colloids, and the like. The use of such media and agents for pharmaceutical active substances is well known in the art. Supplementary active ingredients can also be incorporated into the compositions. The phrase “pharmaceutically-acceptable” refers to molecular entities and compositions that do not produce an allergic or similar untoward reaction when administered to a host.
Delivery vehicles such as liposomes, nanocapsules, microparticles, microspheres, lipid particles, vesicles, and the like, may be used for the introduction of the compositions of the present invention into suitable host cells. In particular, the rAAV vector delivered transgenes may be formulated for delivery either encapsulated in a lipid particle, a liposome, a vesicle, a nanosphere, or a nanoparticle or the like.
Such formulations may be preferred for the introduction of pharmaceutically acceptable formulations of the nucleic acids or the rAAV constructs disclosed herein. The formation and use of liposomes is generally known to those of skill in the art. Recently, liposomes were developed with improved serum stability and circulation half-times (U.S. Pat. No. 5,741,516). Further, various methods of liposome and liposome like preparations as potential drug carriers have been described (U.S. Pat. Nos. 5,567,434; 5,552,157; 5,565,213; 5,738,868 and 5,795,587).
Liposomes have been used successfully with a number of cell types that are normally resistant to transfection by other procedures. In addition, liposomes are free of the DNA length constraints that are typical of viral-based delivery systems. Liposomes have been used effectively to introduce genes, drugs, radiotherapeutic agents, viruses, transcription factors and allosteric effectors into a variety of cultured cell lines and animals. In addition, several successful clinical trails examining the effectiveness of liposome-mediated drug delivery have been completed.
Liposomes are formed from phospholipids that are dispersed in an aqueous medium and spontaneously form multilamellar concentric bilayer vesicles (also termed multilamellar vesicles (MLVs). MLVs generally have diameters of from 25 nm to 4 μm. Sonication of MLVs results in the formation of small unilamellar vesicles (SUVs) with diameters in the range of 200 to 500 .ANG., containing an aqueous solution in the core.
Alternatively, nanocapsule formulations of the rAAV may be used. Nanocapsules can generally entrap substances in a stable and reproducible way. To avoid side effects due to intracellular polymeric overloading, such ultrafine particles (sized around 0.1 μm) should be designed using polymers able to be degraded in vivo. Biodegradable polyalkyl-cyanoacrylate nanoparticles that meet these requirements are contemplated for use.
In addition to the methods of delivery described above, the following techniques are also contemplated as alternative methods of delivering the rAAV compositions to a host. Sonophoresis (ie., ultrasound) has been used and described in U.S. Pat. No. 5,656,016 as a device for enhancing the rate and efficacy of drug permeation into and through the circulatory system. Other drug delivery alternatives contemplated are intraosseous injection (U.S. Pat. No. 5,779,708), microchip devices (U.S. Pat. No. 5,797,898), ophthalmic formulations (Bourlais et al., 1998), transdermal matrices (U.S. Pat. Nos. 5,770,219 and 5,783,208) and feedback-controlled delivery (U.S. Pat. No. 5,697,899).
Kits and Related Compositions
The isolated nucleic acids, compositions, rAAV vectors, rAAVs, etc. described herein may, in some embodiments, be assembled into pharmaceutical or diagnostic or research kits to facilitate their use in therapeutic, diagnostic or research applications. A kit may include one or more containers housing the components of the invention and instructions for use. Specifically, such kits may include one or more agents described herein, along with instructions describing the intended application and the proper use of these agents. In certain embodiments agents in a kit may be in a pharmaceutical formulation and dosage suitable for a particular application and for a method of administration of the agents. Kits for research purposes may contain the components in appropriate concentrations or quantities for running various experiments.
The kit may be designed to facilitate use of the methods described herein by researchers and can take many forms. Each of the compositions of the kit, where applicable, may be provided in liquid form (e.g., in solution), or in solid form, (e.g., a dry powder). In certain cases, some of the compositions may be constitutable or otherwise processable (e.g., to an active form), for example, by the addition of a suitable solvent or other species (for example, water or a cell culture medium), which may or may not be provided with the kit. As used herein, “instructions” can define a component of instruction and/or promotion, and typically involve written instructions on or associated with packaging of the invention. Instructions also can include any oral or electronic instructions provided in any manner such that a user will clearly recognize that the instructions are to be associated with the kit, for example, audiovisual (e.g., videotape, DVD, etc.), Internet, and/or web-based communications, etc. The written instructions may be in a form prescribed by a governmental agency regulating the manufacture, use or sale of pharmaceuticals or biological products, which instructions can also reflects approval by the agency of manufacture, use or sale for animal administration.
The kit may contain any one or more of the components described herein in one or more containers. As an example, in one embodiment, the kit may include instructions for mixing one or more components of the kit and/or isolating and mixing a sample and applying to a subject. The kit may include a container housing agents described herein. The agents may be in the form of a liquid, gel or solid (powder). The agents may be prepared sterilely, packaged in syringe and shipped refrigerated. Alternatively it may be housed in a vial or other container for storage. A second container may have other agents prepared sterilely. Alternatively the kit may include the active agents premixed and shipped in a syringe, vial, tube, or other container. The kit may have one or more or all of the components required to administer the agents to a subject, such as a syringe, topical application devices, or IV needle tubing and bag.
Exemplary embodiments of the invention will be described in more detail by the following examples. These embodiments are exemplary of the invention, which one skilled in the art will recognize is not limited to the exemplary embodiments.
EXAMPLES
Introduction to the Examples
Alpha-1 antitrypsin (AAT) deficiency is one of the most commonly inherited diseases in North America, with a carrier frequency of approximately 4% in the US population. The most common mutation arises as a single base pair change (Glu342Lys, PI*Z, SEQ ID 4) and leads to the synthesis of the mutant Z-AAT protein, which polymerizes and accumulates within hepatocytes, precluding its efficient secretion. The subsequent relative deficiency of serum AAT predisposes to chronic lung disease. Twelve to 15% of homozygous PI*ZZ patients develop significant liver disease, ranging from neonatal hepatitis, cholestatic jaundice and cirrhosis to adult-onset cirrhosis and hepatocellular carcinoma. Liver injury is considered to be a consequence of the pathological accumulation of mutant Z-AAT protein polymers within the endoplasmic reticulum of hepatocytes.
Strategies to alleviate the liver disease are focused on decreasing the presence of the mutant Z-AAT protein in the hepatocytes by either reducing expression of the mutant protein, or augmenting its proteolysis or secretion. In vivo studies of an allele-specific small interfering RNA (siRNA) directed against PI*Z AAT in the Pi*Z transgenic mouse model of AAT deficiency have been performed. In vitro studies using U6-driven shRNA clones in recombinant adeno-associated virus (rAAV) backbones have identified an effective allele-specific siRNA sequence (termed p10) that can reduce Pi*Z AAT protein levels while minimizing knockdown of the normal Pi*M AAT. Using the AAV8 capsid, rAAV-U6-p10 was packaged and administered by hepatic portal vein injection into Pi*Z transgenic mice for direct in vivo targeting of the liver. A similarly delivered AAV8-packaged non-specific siRNA, rAAV-U6-NC, served as a control (NC). Histological data from these studies revealed areas of complete or partial elimination of Z-AAT protein in the liver at 10 days post-injection in the p10 cohort. Analysis of the serum Z-AAT levels shows a kinetically significant reduction for 4 weeks post-injection in the p10 cohort when compared to NC control cohort. To examine the allele-specificity, AAV8-packaged Pi*M-AAT was co-administered with each shRNA construct. For both the p10+Pi*M and NC+Pi*M groups, there was considerable expression of AAT in the liver by histological staining and there was no significant difference in serum AAT levels.
The Pi*Z mutation (Glu342Lys) within exon 5 of alpha-1 antitrypsin (AAT) causes a plasma AAT deficiency (A1AD) which exposes lung tissue to uncontrolled proteolytic attack and can result in emphysema. Pi*Z mutant AAT is retained within the hepatocytes and causes a liver disease in  ̃12% of patients with the deficiency. Delivering wild-type copies of AAT does not address the liver pathology so down-regulation strategies including siRNA have been targeted to AAT message within hepatocytes. Since mutant AAT-PiZ exhibits a gain-of-function hepatocellular toxicity accumulating in the endoplasmic reticulum, decreasing AAT-Pi*Z mRNA levels (and therefore the protein) may ameliorate or even reverse the liver pathology. In addition, increased secretion of functional AAT protein will theoretically protect the lungs from neutrophil elastase and associated proteolytic enzymes.
The strategies described herein include the development of rAAV mediated therapies to both augment serum levels of normal AAT and down-regulate mutant AAT using miRNA. To achieve expression and secretion of wild-type AAT while simultaneously reducing AAT-PiZ levels. Three miRNA sequences targeting the AAT gene were selected in some embodiments and cloned into two different locations of the expression cassette. The first location is within the intron of the CB promoter driving expression of GFP, and the second location was between the polyA sequence and the 3′ end of the gene, an additional construct with miRNAs at both locations was also created. These three constructs were packaged into rAAV8 and delivered to transgenic mice expressing the mutant form of human AAT (hAAT Pi*Z) at 6×1011 vector particles per mouse via the tail vein. These experiments showed about a 60% to 80% reduction in secreted AAT protein in mice serum when compared with CB-GFP control vector injected group. It was determined that the 3XD construct was the most efficient for knocking down hAAT, in some embodiments. Liver immuno-histology also showed hAAT Pi*Z protein clearance at 4 weeks after vector delivery. Using an AAT sequence with silent base pair changes to prevent the miRNA silencing allows both up regulation of wildtype AAT gene expression while simultaneously knocking down levels of mutant protein with a single rAAV vector construct.
Materials and Methods
rAAV9 Packaging and Purification: Recombinant AAV9 vectors used in this study were generated, purified, and titered by the UMass Gene Therapy Vector Core as previously described.
Cell Culture and Transfection: HEK-293 cells were cultured in Dulbecco's modified Eagle's medium supplemented with 10% fetal bovine serum and 100 mg/1 of penicillin-streptomycin (Gemini Bio-products Cat#400-109, Woodland, Calif.). Cells were maintained in a humidified incubator at 37° C. and 5% CO2. Plasmids were transiently transfected using Lipofectamine 2000 (Cat#11668-027 Invitrogen, Carlsbad, Calif.) according to the manufacturer's instructions. Cell culture supernatants or cell lyses were collected accordingly.
Serum AAT ELISAs
Human AAT ELISA: Total AAT protein levels were detected by ELISA. High binding extra, 96-well plate (Immulon 4, cat#3855 Dynatech Laboratories, Inc., Chantilly, Va.) were coated with 100 μl of goat anti-hAAT (1:500 diluted; cat#55111MP Biomedicals, Irvine Calif.) in Voller's buffer overnight at 4° C. After blocking with 1% non-fat dry milk in PBS-T, duplicate standard curves (hAAT; cat#16-16-011609, Athens Research and Technology, Athens, Ga.,) and serially diluted unknown samples were incubated in the plate at room temperature for 1 hr, a second antibody, Goat anti-hAAT(HRP) (1:5000 diluted, cat #ab7635-5, Abcam Inc, Cambridge, Mass.) was incubated at room temperature for 1 h. The plate was washed with phosphate-buffered saline (PBS)-Tween 20 between reactions. After reaction with TMB peroxidase substrate (KPL, Inc, Gaithersburg, Md.) reactions were stopped by adding 2 N H2SO4 (cat#A300-500 Fisher, Pittsburgh, Pa.). Plates were read at 450 nm on a VersaMax microplate reader (Molecular Devices).
Z-AAT ELISA: Human Z-AAT protein levels were detected by ELISA using coating antibody (1:100 diluted mouse-anti-human Alpha-1-Antitrypsin-Z, clone F50.4.1 Monoclonal Antibody cat#MON5038, Cell Sciences, Inc., Canton, Mass.). Standard curves were created using PIZ mouse serum with 5% BSA (cat#B4287 Sigma, St. Louis, Mo.). Serially diluted unknown samples were incubated in the plate at 37° C. for 1 hr, secondary antibody and following the step were same as the standard human-AAT ELISA described above, except secondary antibody was diluted in 5% BSA and incubated in the plate at 37° C. for 1 hr.
c-Myc ELISA: c-Myc tag levels were quantified by a similar method as described above. Plates were coated with a c-Myc antibody (1:1000 diluted Goat anti-c-Myc, MA cat#AB19234 Abcam, Cambridge Mass.), plates were then blocked with 5% BSA at 37° C. for 1 hr. Standard curves were generated from supernatants collected from c-Myc-AAT transfected cells.
Real-time RT-PCR
RNA Extraction: Flash frozen mouse liver tissue was ground up in a pestle and mortar and used to extract either small or total RNA using the mirVana miRNA RNA Isolation Kit (cat#AM1560 Ambion, Austin, Tex.) according to the manufacturer's instructions.
microRNA qRT-PCR: microRNA was primed and reverse-transcribed with TaqMan MicroRNA reverse transcription Kit (cat#4366596, Applied Biosystems Foster City, Calif.). Quantitative PCR were performed in duplicate with gene specific RT-miRNA primers and PCR Assays were designed by Applied Biosystems, using TaqMan Gene Expression Master mix (cat#436916, Applied Biosystems, Foster City, Calif.) in a StepOne Plus real-time PCR instrument (Applied Biosystems, Foster City, Calif.).
PIM and PIZ qRT-PCR: Total RNA was primed with oligo(dT) and reverse-transcribed with SuperScript III First-Strand Synthesis kit for RT-PCR (Cat#18989-51, Invitrogen, Carlsbad, Calif.). Quantitative PCR were performed by gene-specific primer pairs. PIM and PIZ share the primers but differ in the probes. Forward primer CCAAGGCCGTGCATAAGG (SEQ ID NO: 29), Reverse primer: GGCCCCAGCAGCTTCAGT (SEQ ID NO: 30), PIZ probe: 6FAM-CTGACCATCGACAAGA-MGBNFQ (SEQ ID NO: 31) and PIM probe: 6FAM-CTGACCATCGACGAGA-MGBNFQ (SEQ ID NO: 32), Reactions were performed using TaqMan Gene Expression Master mix (cat#436916, Applied Biosystems, Foster City, Calif.) in a StepOne Plus real-time PCR instrument (Applied Biosystems, Foster City, Calif.).
Z-AAT Transgenic Mice and rAAV9 Delivery: The PiZ-transgenic mice used in this study have been described previously8. All animal procedures were performed according to the guidelines of the Institutional Animal Care and Use Committee of the University of Massachusetts Medical School. Recombinant AAV9 vector was administered by mouse tail veil injection. The injections were performed in the most accessible vessels veins that run the length of both lateral aspects of the tail by grasping the tail at the distal end. Bleeds were performed through the facial vein pre-injection and every week after tail vein rAAV9 delivery until termination of the studies.
Liver Histology: For determination of histological changes, liver samples were fixed in 10% neutral-buffered formalin (Fisher Scientific), and embedded in paraffin. Sections (5 μm) were stained with hematoxylin and eosin and periodic acid-Schiff (PAS) with or without diastase digestion.
Immuno-histochemistry for hAAT was performed as previously described14, briefly tissue sections (5 μm) were deparaffinized, rehydrated, and blocked for endogenous peroxidase with 3% hydrogen peroxide in methanol for 10 minutes. To detect hAAT expression, tissue sections were incubated with primary antibody, rabbit antihuman AAT (1:800; RDI/Fitzgerald Industries, Concord, Mass.), for overnight at 4° C. Staining was detected using ABC-Rb-HRP and DAB kits (Vector Laboratories, Burlingame, Calif.).
Histology Image Analysis. Slides were stained for PASD to remove glycogen. Whole digital slide images were created using an Aperio CS ScanScope (V, CA) and analyzed using the positive pixel count algorithm (version 9). PASD-positive globules were expressed as the proportion of strong positive pixels to total pixels using a hue value of 0.9, hue width of 0.15, and color saturation threshold of 0.25. The intensity threshold for strong positivity was set to an upper limit of 100.
Analysis of Z-AAT Protein Monomer and Polymer. For soluble/insoluble protein separation, 10 mg of whole liver was added to 2 ml buffer at 4° C. (50 mmol/1 Tris-HCl (pH 8.0), 150 mmol/1 NaCl, 5 mmol/1 KCl, 5 mmol/1 MgCl2, 0.5% Triton X-100, and 80 μl of complete protease inhibitor stock). The tissue was homogenized in a prechilled Dounce homogenizer for 30 repetitions, then vortexed vigorously. A 1-ml aliquot was passed through a 28-gauge needle 10 times. The total protein concentration of the sample was determined, and a 5-μg total liver protein sample was aliquoted and centrifuged at 10,000 g for 30 minutes at 4° C. Supernatant (soluble (S) fraction) was immediately removed into fresh tubes; extreme care was taken to avoid disturbing the pellet (insoluble (I) fraction). The insoluble polymers pellet (I fraction) was denatured and solubilized via addition of 10 l chilled cell lysis buffer (1% Triton X-100, 0.05% deoxycholate, 10 mmol/1 EDTA in phosphate-buffered saline), vortexed for 30 seconds, sonicated on ice for 10 minutes and vortexed. To each soluble and insoluble sample, 2.5 sample buffer (50% 5 sample buffer (5% sodium dodecyl sulfate, 50% glycerol, 0.5 mol/l Tris (pH 6.8)), 10% mercaptoethanol, 40% ddH2O) was added at a volume of 50% of the sample volume. Samples were boiled and loaded for sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE); equal amounts of total liver protein were loaded per soluble-insoluble pair in quantitative experiments. Densitometry was performed using Image J Software (NIH, Bethesda, Md.).
Serum Chemistries: Serum samples were analyzed by UMass Mouse Phenotyping Center Analytical Core, using the NExCT Clinical Chemistry Analyzer (Alfa Wassermann Diagnostic Technologies, West Caldwell, N.J.). Serum was analyzed for alanine aminotransferase (ALT) and aspartate aminotransferase (AST) according the manufacturers specifications.
miRNA Microarray Expression Analysis: 8 μg of total RNA were isolated from flash frozen mouse livers using the mirVana miRNA isolation kit (Ambion). The experimental design included six groups with RNA samples from 5 mice each which were assayed on single color arrays for a total of 30 independent microarrays. In brief, the RNA was labeled with Cy5 and hybridized to dual-channel microarray μParaFlo microfluidics chips (LC Sciences) containing miRNA probes to mouse mature miRNAs available in the Sanger miRBase database (Release 16.0) as previously described15. Each of the spotted detection probes consisted of a nucleotide sequence complementary to a specific miRNA sequence and a long non-nucleotide spacer that extended the specific sequence away from the chip surface. Fluorescence images were collected using a laser scanner (GenePix 4000B, Molecular Device) and digitized using Array-Pro image analysis software (Media Cybernetics). The data was analyzed including background subtraction, using a LOWESS (locally weighted regression) method on the background-subtracted data as previously described16. The normalization is to remove system related variations, such as sample amount variations, and signal gain differences of scanners. Detection was determined to be positive only if transcripts had a signal intensity higher than 3× (background SD) and spot CV<0.5. CV as calculated by (SD)/(signal intensity), and in which repeating probes on the array produced signals from at least 50% of the repeating probes above detection level. Data is represented as a Log 2 transformation. The data was further filtered to remove miRNAs with (normalized) intensity values below a threshold value of 32 across all samples. t-Test were performed between “control” and “test” sample groups where T-values are calculated for each miRNA, and p-values are computed from the theoretical t-distribution. If p<0.05, it is plotted as red spot in a log scatter plot.
Artificial miRNAs are as Efficient as shRNAs at Downregulating Alpha-1 Antitrypsin In Vitro
Efficient Z-AAT knockdown has been demonstrated in vivo and in vitro using shRNAs expressed from a pol III U6 promoter using rAAV8. In order to determine if an alternative and potentially safer approach could be employed using polymerase II driven miRNA expression, three distinct miRNAs targeting the human AAT gene were cloned into the intron of a hybrid chicken beta-actin (CB) promoter driving GFP expression (Table 2 and FIG. 1). An in vitro comparison of the previously used U6 driven shRNAs against the pol II driven miRNAs was carried out on cell lines expressing the human Pi*Z AAT gene. Initially a delay in Z-AAT knockdown with the miRNAs at 24 hrs was observed, but an eventual comparable  ̃35% reduction in secreted AAT protein by 48 and 72 hrs was observed for both constructs as compared to GFP controls (FIG. 1a). A similar reduction was observed in intracellular AAT protein levels assayed from the cell pellets at 72 hrs (FIG. 1b).
rAAV9 Expressed miRNAs Mediate Efficient AAT Knockdown In vivo
Based on the in vitro findings, the construct with the three intronic miRNA sequences (intronic 3XmiR) along with three other constructs containing the individual miRNAs directed against the Z-AAT were packaged in rAAV and tested in vivo in the PiZ transgenic mice. Five groups of 5 week old mice received: rAAV9-CB-GFP, rAAV9-CBintronic3xmiR-GFP or vector with either one of the individual miRNA via a tail vein injection with 5.0×1011 vector particles (vps) of rAAV9. Mice were bled weekly for a total of 5 weeks to check for circulating Z-AAT levels and were sacrificed on day 35 post rAAV delivery. As shown in FIG. 2, mice receiving 3X intronic miRNAs (intronic 3Xmir) had on average a sustained 50-60% decrease in serum AAT levels when compared to baseline values while mice receiving the single intronic miRNAs had on average a knockdown of 30% as compared to mice receiving the GFP control vector.
To evaluate the effect that miRNA mediated knockdown was having at the organ level, the livers of these mice were evaluated 5 weeks post rAAV delivery for abundance of intracellular Z-AAT. As can be appreciated from liver immuno-stains for human AAT in FIG. 3, there was a marked decrease in AAT positive staining in the livers belonging to mice in the rAAV9-intronic3XmiR-GFP treated group. In addition to the drastic reduction in AAT positive staining, likewise there was a dramatic decrease in intracellular AAT globules as determined by diastase resistant PAS (PASD) positive staining. Importantly the reduction in both PASD and hAAT staining was accompanied by a reduction in inflammatory foci in the GFP group (FIG. 3). This suggests that the reduction in hAAT accumulation in the PiZ mice livers may be alleviating inflammation as evidenced by the reduction in inflammatory infiltrates.
Onset and Degree of Knockdown are Dependent on miRNA Location within the Expression Cassette
While delivering 3 miRNAs within the intron of the CB promoter was successful at lowering Z-AAT expression, it was unclear whether the location of the miRNAs within the expression cassette had any effect on their efficiency. It was investigated whether cloning the 3 miRNAs between the 3′ end of the GFP gene and the polyA tail would have an effect on the kinetics of AAT knockdown Likewise it was evaluated whether cloning the 3 miRNAs at both locations would increase (e.g., double) the amount of miRNAs being produced and lead to a further enhancement of AAT knockdown. As in the previous experiments, Z-AAT transgenic mice received 5×1011 vector particles of rAAV9 vectors expressing the miRNAs either from the intron (intronic-3XmiR), polyA region (PolyA-3XmiR) or at both locations at once (Double-6XmiR) (see diagram in FIG. 4). Analysis of serum Z-AAT levels revealed that by four weeks the PolyA-3XmiR and Double-6XmiR were more effective than the intronic-3XmiR vector at clearing serum Z-AAT levels by 85-70% and in some cases by up to 95% with the Double-6XmiR vector (FIG. 4). Real-time quantitative RT-PCR analysis of liver tissue from these mice was performed to assay for the abundance of each of the three artificial vector derived miRs (910, 914, 943). As indicated in FIG. 5, both the PolyA-3XmiR and Double-6XmiR vectors produced about two-fold more copies of each of the miRs (FIG. 5).
Having achieved a short-term clinically significant knockdown of more than 50% of Z-AAT protein levels it was necessary to determine if this knockdown could be sustained for longer periods of time. Once again the three vector constructs were delivered via the tail vein at a slightly higher titer of 1.0×1012 vector particles per mouse and serum Z-AAT levels were monitored weekly for 3 months. The knockdown onset of the three vector varied within 7 weeks, the Double-6XmiR vector achieved 90% knockdown 2 weeks after delivery, the PolyA-3XmiR reached this mark by the third week while the intronic-3XmiR vector remained in the range of 50-65% knockdown for the first 7 weeks (FIG. 6a). Further analysis of liver homogenates to determine whether this reduction was in the monomer or polymer pools of Z-AAT was performed on all groups. Monomer and polymer Z-AAT fractions were separated under nondenaturing conditions after which, the fractions were denatured and quantitatively assessed by immunoblotting. A reduction was observed in all groups in the monomer pool 3 months after miRNA treatment. Densitometric analysis of the bands showed significant differences in the PolyA-3XmiR and Double-6XmiR as compared to mice treated with a control vector (FIG. 6 b-d). This knockdown observed at two weeks in FIG. 6a was accompanied by significant reduction in serum ALT and AST in the Double-6XmiR group with clear decreasing trends in the two other groups expressing anti-AAT miRs (FIGS. 6e and 6f). Although Z-AAT levels rose slightly for animals in the Double-6XmiR and PolyA-3XmiR groups between week 7 and 13, all three vectors stabilized at a sustained level of about 75% knockdown of Z-AAT for the remainder of the study (FIG. 6).
In vitro Delivery of miRNAs Against Z-AAT and Gene Correction with M-AAT Using a Single Vector
A dual-function vector that would simultaneously augment protein levels of the wild-type M-AAT protein, thereby addressing both liver disease caused by the toxic gain-of-function of Z-AAT polymers and the loss-of-function caused by the absence of circulating M-AAT, was evaluated. To achieve this, the GFP gene was replaced with a wild-type AAT gene that had silent base pair changes at the miRNAs' target sites, thus making it impervious to the miRNA mediated knockdown. HEK-293 cells were co-transfected with two plasmids, one of the plasmid expressed Z-AAT and the other one was either the Double-6XmiR-GFP, Double-6XmiR-AAT (containing the hardened, knockdown-impervious AAT gene) or a control. The transfected cells were incubated for 72 hrs and RNA was harvested from cell pellets for a quantitative RT-PCR analysis of Z-AAT and M-AAT transcripts. Analysis of Z-AAT mRNA levels revealed the both Double-6XmiR-GFP and Double-6XmiR-AAT produced a significant knockdown of up to 37-fold in Z-AAT mRNA copies as compared to the mock transfected cells (FIG. 7a). Furthermore, quantitative RT-PCR for wild-type M-AAT transcripts from the same RNA pool, revealed that the Double-6XmiR-AAT construct upregulated M-AAT expression by more than 100-fold over the endogenous levels observed in control transfected cells (FIG. 7b).
In Vivo Delivery of Dual-function Vectors
Taking the in vitro findings into consideration as well as the more rapid onset and the decreased variability in knockdown observed with the Double-6XmiR and PolyA-3XmiR vectors (FIG. 6), both of these miRNA configurations were tested as dual function vectors in vivo. Three cohorts of seven mice each were dosed with 1.0×1012 vector particles with either a GFP control, Double-6XmiR-CB-AAT or a PolyA-3XmiR-CB-AAT rAAV9 vectors. Serum was harvested weekly from the mice for 13 weeks and was analyzed for Z-AAT serum levels with a PiZ specific ELISA and for M-AAT levels with an ELISA detecting the cMYC tag on the M-AAT cDNA. Changes in Z-AAT serum levels were comparable to previous experiments, with a sustained knockdown around 75-85% for both vectors (FIG. 8a bottom panel). A more rapid onset of knockdown was seen with the Double-6XmiR vector but the PolyA-3XmiR vector achieved similar knockdown by the fourth week. As the Z-AAT knockdown progressed, a concomitant rise in circulating M-AAT was observed from mice receiving the dual function vectors (FIG. 8a upper panel).
Surprisingly, while the knockdown for both vectors was similar four weeks post delivery, the production of M-AAT was substantially different. The PolyA-3XmiR-CB-AAT vector produced 8-10 times more M-AAT than the Double-6XmiR-CB-AAT vector. Liver RNA was extracted from these mice at the end of the study to quantify the mRNA levels of Z-AAT and M-AAT. A precipitous decrease in Z-AAT mRNA occurred in both cohorts of mice receiving vectors with miRNAs as compared to mice receiving a rAAV9-CB-GFP control (FIG. 8B). A quantitative RT-PCR for M-AAT was also performed, to verify production of M-AAT at the RNA level and to determine if the difference in M-AAT production between dual-function vectors was related to mRNA transcription. Despite the clear difference in M-AAT serum protein levels, there was no statistically significant difference in the M-AAT mRNA levels between the two groups (FIG. 8C). This indicates that mRNA processing and translation but not the level of transcription may be affected in the Double-6XmiR-CB-AAT group, in some cases.
Analysis of Global Liver miRNA Profiles after Delivery of Artificial miRNAs with rAAV9
A microarray analysis of endogenous mouse miRNAs from liver tissue for 6 groups of mice with 5 mice per group was performed on 30 separate microfluidic chips using samples obtained from the long-term Z-AAT knockdown experiments (FIG. 6), along with 5 untreated Z-AAT transgenic mice and 5 C57/BL6 mice. In order to determine basal differences imparted by the human Z-AAT gene in mice, an initial comparison between untreated PiZ mice and wildtype C57BL6 mice was performed. As shown in FIG. 9a and Table 3, there were only 4 statistically significant differences among these mice with only miR-1 having a log 2 ratio greater than 2, being upregulated in PiZ mice. The effects of rAAV9-CB-GFP, rAAV9-Double-6XmiR-CB-GFP, rAAV9-PolyA-3XmiR-CB-GFP and rAAV9-intronic-3XmiR-CB-GFP liver transduction on liver miRNA profiles were compared. Surprisingly the expression of the artificial vector derived miRNAs had minimal impact on global miRNA profiles (see FIG. 9b-d). Statistically significant differences between untreated PiZ mice and rAAV9 treated mice were observed in 2-6 differentially expressed miRNAs. Of these differentially expressed miRNAs the one with the largest change was miR-1 which was down-regulated back down to levels observed in the C57B16. This correction of miR-1 up-regulation in PiZ mice was observed in all groups including the mice receiving only rAAV9-GFP. Thus it seems to be dependent on rAAV9 delivery and not on artificial miRNA delivery.
The results presented in these examples describe a combinatorial therapeutic approach for the treatment of both liver and lung disease present in alpha-1 antitrypsin deficiency. This therapeutic approach is based on a single dual function AAV vector to deliver both miRNAs targeting AAT for clearance of mutant mRNA along with a miRNA resistant AAT cDNA for augmentation of wild-type protein. The data presented herein support this approach as the biological activities of the miRNAs are demonstrated both by cell culture experiments, and in vivo after numerous experiments with tail vein delivery of rAAV9-pseudotyped vectors. Depending on the configuration of the miRNAs, a long-term knockdown of circulating serum Z-AAT in a range of 50-95% was consistently achieved. Furthermore, in the case of dual function vectors this knockdown was accompanied by equally sustained expression and secretion of wild-type M-AAT.
Knockdown of mutant Z-AAT protein is observed in PiZ transgenic mice using a rAAV8 vector expressing U6 driven shRNAs. Initial cell culture experiments determined that by 72 hours the efficiency of the miRNAs used in this study were comparable to shRNAs (FIG. 1). The in vivo experiments described herein corroborated this finding, as a significant decrease in Z-AAT was observed with administration of the rAAV9-CBintronic3xmiR-GFP rAAV9 vector (FIG. 2). These experiments also highlighted an enhanced effect that was obtained by using 3 anti-AAT miRNAs with different target sequences as none of the vectors with a single miRNA achieved the level of knockdown seen when they were delivered in combination (FIG. 2). Another biological effect aside from Z-AAT serum reduction that was observed included a significant and widespread decrease in the accumulation of Z-AAT within the hepatocytes and a reduction of the inflammatory lymphocyte foci within the liver (FIG. 3).
Surprisingly, anti-AAT miRNA efficacy was improved by altering the location of the miRNA within the expression cassette. Initial short-term experiments demonstrated that expressing the miRNAs from the 3′ end of the GFP gene rather than from the intron of the CB promoter lead to a 25% increase in the silencing capabilities of the miRNAs and also a to significant decrease in the variability of this effect. Furthermore, doubling the effective miRNA dose per vector by having the miRNAs expressed from both locations did lead to more rapid onset of Z-AAT knockdown (FIG. 4). Moreover, increased miRNA production was seen for both the PolyA-3XmiR-CB-GFP and the Double-6XmiR-CB-GFP vectors as compared to the rAAV9-intronic3xmiR-GFP vector. This indicates that, in some embodiments, miRNA processing from the intron of the CB promoter may be not as efficient as from the 3′ end of the GFP gene. In other embodiments, long-term experiments showed that initial kinetic differences in knockdown from the three vectors wanes overtime and by eight weeks the intronic3xmiR-GFP decreases in variability and augments in silencing efficacy.
The potency and stability of the decrease in serum Z-AAT observed in vivo suggests that either of these vectors would lower Z-AAT levels in Pi*ZZ patients to therapeutic levels, even below those seen in Pi*MZ heterozygote patients. However, in some cases, maximal clinical benefit would be derived from a concomitant rise in M-AAT circulation. In this regard, the dual function vectors were designed to also deliver a miRNA-resistant M-AAT cDNA. Cell culture experiments showed the feasibility of this strategy as was shown by a decrease in Z-AAT specific mRNA with a simultaneous rise in M-AAT using a single pro-viral plasmid (FIG. 7). These experiments supported an in vivo study of the dual function vectors. The results from those experiments confirmed the in vitro data, clearly demonstrating the feasibility of concomitant knockdown and augmentation of mutant and wild-type protein respectively. These experiments also revealed that the double configuration of miRNAs had a more rapid onset of Z-AAT knockdown but the overall efficacy over time was comparable to the PolyA-3XmiR-CB-AAT vector. In addition to improved knockdown kinetics of the Double-6XmiR-CB-AAT vector, a decreased output of M-AAT was also observed (FIG. 8a). Initially it was hypothesized that this may have been a result of decreased M-AAT mRNA production due to the presence of miRNA within the intron of this construct, but as shown in FIG. 8c, there was a statistically significant difference in M-AAT mRNA was not observed between the two groups. While mRNA transcription and stability are not affected by the presence of miRNAs within the intron, their translation into protein may be hindered as observed in the decrease circulating M-AAT levels in the serum of these mice.
A consideration for a clinical therapy is an effect of artificial miRNA expression on the endogenous miRNA profiles of the target organ. In order to determine if rAAV9 expressed anti-AAT miRNAs were disturbing the endogenous miRNA profiles of the liver, the livers of 30 mice were interrogated at the end of the study described in FIG. 6 with a miRNA microarray. As can be observed from FIG. 9, neither did the delivery of rAAV9-GFP or of the vectors expressing miRNAs have a significant impact on miRNA profiles. Notably, mir-122 which is the most abundant miRNA produced in the liver was unaffected in any group. While some miRNAs were found to be expressed at statistically different levels among the groups, they were mostly on the border of having a 2-fold change with one exception. Interestingly, mir-1 seemed to consistently have upwards of a 2-fold change with rAAV9 intervention. In the case of this miRNA the fold change with rAAV intervention was in the direction of reverting the levels back to those found in wildtype C57BL6 mice (FIG. 9a). Thus, in summary, miRNA profiles were unperturbed and in some cases ‘corrected’ back to wildtype levels with rAAV9 delivery.
These findings indicate that other diseases states requiring the combination of augmentation of a functional allele and suppression of a mutant allele may be addressed in a similar fashion. One such example is Huntington Disease (HD), in which mutant alleles cause a severe autosomal dominant disease, but in which an allele-specific knockdown might only be feasible if the functional allele were modified to convey resistance to a miRNA-based knockdown. It is also significant that these manipulations result in minimal perturbations of endogenous miRNA profiles. This is potentially important for considering the safety of single agent miRNA-based approaches, which would be useful in other anti-viral therapies, e.g., therapies directed against HBV or HCV. As with the genetic diseases considered above, these are conditions in which the down-regulation of target genes for prolonged periods of time may be advantageous. Therefore, emergence of the rAAV-based miRNA platform as a means to address these problems would be useful as well.







TABLE 2





Artificial miRNA sequences















miRNA910 (SEQ ID NO: 21)


5′-


TAAGCTGGCAGACCTTCTGTCGTTTTGGCCACTGAGTGACGACAGAAGCT


GCCAGCTTA


 


miRNA914 (SEQ ID NO: 22)


5′-


AATGTAAGCTGGCAGACCTTCGTTTTGGCCACTGACTGACGAAGGTCTCA


GCTTACATT


 


miRNA943 (SEQ ID NO: 23)


5′-


ATAGGTTCCAGTAATGGACAGGTTTGGCCACTGACTGACCTGTCCATCTG


GAACCTAT
















TABLE 3







Statistically significant changes in liver miRNA profiles













Group 1
Group 2





Mean
Mean




Intensity
Intensity
Log2


Reporter Name
p-value
(n = 5)
(n = 5)
(G2/G1)







B6-Control
PiZ-Control






mmu-miR-762
2.39E−02
525
1,099
1.07


mmu-miR-23a
4.03E−02
1,247
1,593
0.35


mmu-miR-1
4.95E−02
126
2,776
4.46


mmu-miR-341*
4.97E−02
4,340
2,287
−0.92







PiZ-GFP
PiZ-Control





mmu-miR-1
6.03E−03
5
2.776
9.13


mmu-miR-148a
7.48E−03
1,841
1,058
−0.80


mmu-miR-720
9.33E−03
1,264
3,440
1.44


mmu-miR-30c
1.03E−02
2,830
1,757
−0.69


mmu-miR-146a
1.71E−02
362
175
−1.05


mmu-miR-30d
4.64E−02
627
454
−0.47







PiZ-PolyA
Piz-Control





mmu-miR-2145
1.40E−02
573
114
−2.32


mmu-miR-1
2.82E−02
22
2,776
6.95


mmu-miR-690
2.41E−02
3.071
534
−2.52


mmu-miR-720
4.31E−02
1,816
3,440
0.92







PiZ-6X
PiZ-Control





mmu-miR-146a
1.53E−02
445
175
−1.35


mmu-miR-1
3.04E−02
115
2,776
4.59









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17. Naldini, L. Ex vivo gene transfer and correction for cell-based therapies. Nature Reviews Genetics 12, 301-315 (2011).
18. Loiler, S. A., Conlon, T. J., Song, S., Tang, Q., Warrington, K. H., Agarwai, A., Kapturczak, M., Li, C., Ricordi, C., Atkinson, M. A., Muzyczka, N., and Flotte, T. R. Targeting recombinant adeno-associated virus vectors to enhance gene transfer to pancreatic islets and liverGene Therapy (2003) 10, 1551-1558).
Having thus described several aspects of at least one embodiment of this invention, it is to be appreciated that various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the spirit and scope of the invention. Accordingly, the foregoing description and drawings are by way of example only and the invention is described in detail by the claims that follow.
As used herein, the terms “approximately” or “about” in reference to a number are generally taken to include numbers that fall within a range of 1%, 5%, 10%, 15%, or 20% in either direction (greater than or less than) of the number unless otherwise stated or otherwise evident from the context (except where such number would be less than 0% or exceed 100% of a possible value).
Use of ordinal terms such as “first,” “second,” “third,” etc., in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one claim element having a certain name from another element having a same name (but for use of the ordinal term) to distinguish the claim elements.
The entire contents of all references, publications, abstracts, and database entries cited in this specification are incorporated by reference herein.

## Claims

1. A recombinant adenoviral associated vector (rAAV) comprising:
(a) a first region that encodes one or more first miRNAs comprising a nucleic acid having sufficient sequence complementary with an endogenous mRNA of a subject to hybridize with and inhibit expression of the endogenous mRNA, wherein the endogenous mRNA encodes a mutant alpha anti-trypsin (AAT) protein; and
(b) a second region encoding an exogenous mRNA that encodes a second protein, wherein the second protein is a wild-type AAT protein, wherein the exogenous mRNA has one or more silent mutations as compared with the endogenous mRNA,
wherein the one or more first miRNAs do not comprise a nucleic acid having sufficient sequence complementary to hybridize with and inhibit expression of the exogenous mRNA, and wherein the first region is positioned between a portion of the second region encoding the last codon of the exogenous mRNA and a polyadenylation sequence of the exogenous mRNA.

2. The rAAV of claim 1, further comprising a third region encoding a one or more second miRNAs comprising a nucleic acid having sufficient sequence complementary to hybridize with and inhibit expression of the endogenous mRNA, wherein the third region is positioned within an untranslated portion of the second region.

3. The rAAV of claim 2, wherein the third region is between the first codon of the exogenous mRNA and a position 1000 nucleotides upstream of the first codon.

4. The rAAV of claim 1, wherein the first region encodes two first miRNAs.

5. The rAAV of claim 1, wherein the first region encodes three first miRNAs.

6. The rAAV of claim 2, wherein the third region encodes two second miRNAs.

7. The rAAV of claim 2, wherein the third region encodes three second miRNAs.

8. The rAAV of claim 1, wherein the AAT protein is a human AAT protein.

9. A composition comprising the recombinant AAV of claim 1.

10. A kit comprising a container housing the composition of claim 9.

11. A method of expressing Alpha 1-Antitrypsin (AAT) protein in a subject, the method comprising:
administering to a subject an effective amount of a rAAV of claim 1.

12. A method of expressing Alpha 1-Antitrypsin (AAT) protein in a subject, the method comprising:
isolating cells or tissue from a subject;
contacting the cells or tissue with an effective amount of a rAAV of claim 1, thereby producing transfected cells or tissue; and

administering the transfected cells or tissue to the subject.

13. The method of claim 12, wherein the tissue is adipose tissue.