bluuebunny/crossref_metadata_2025_split huggingface dataset:
The potential of local immunomodulation and tolerance induction in porcine islet xenotransplantation
Authors: van Bürck Lelia , Seissler Jochen 
Published: February 2013

Transplantation of pancreas or isolated islet cells is currently the only option to cure type 1 diabetes. The success of islet transplantation is still limited by the requirement of large numbers of high quality islets and the shortage of organ donors. Porcine islets are a promising cell source, but the intensive immunosuppressive regimen required to suppress rejection prevents the translation into clinical practice.We aimed to develop a novel method to inhibit the human‐anti‐pig immune reaction by the expression of immunomodulatory molecules in porcine beta cells. Thus, a transgenic pig was generated expressing LEA29Y – a second generation human CTLA4‐Ig fusion protein, which inhibits activation of T cells by CD80/CD86‐CD28 costimulation – under the control of the porcine insulin promotor. Islet‐like clusters (ICC) from neonatal pigs were isolated and transplanted under the kidney capsule of diabetic NOD‐scid‐IL2γnull (NSG) mice. After an in vivo maturation period mice transplanted with wildtype (wt) as well as with LEA29Y transgenic (tg) ICCs developed normal glucose homeostasis. Within 30 days after the transfer of human PBMCs 80% of NSG mice transplanted with wt‐ICCs developed diabetes indicating xenograft rejection. By contrast, LEA‐tg ICCs were completely protected from rejection in all animals (1). Immunohistochemistry revealed a massive intra‐islet T cell infiltration, which was absent in the LEA‐tg ICCs. This proof of principle study suggests that specific expression of immunomodulatory molecules in beta cells does not disturb beta cell function and may have the potential to modulate immune response locally at the transplantation site without systemic immunosuppression.To overcome the strong xenogeneic barrier of the human and cellular immune system a combination of LEA29Y with additional immunomodulatory factors may be required. Recently, Yi and coworkers demonstrated that the treatment with in vitro expanded regulatory T cells (Treg) prevents porcine islet rejection in humanized NSG mice by the suppression of the T cell‐mediated graft destruction (2). Other potential candidates to induce a state of tolerance against porcine islets currently under investigation are molecules targeting innate immunity and factors that prevent the reoccurrence of autoimmunity. Recent advances in xenotransplantation suggest that it may be possible to start with clinical trials using porcine neonatal or adult islets within the near future.References:  1. KLYMIUK N, VAN BÜRCK L, BÄHR Aet al. Xenografted islet‐cell‐clusters from INSLEA29Y transgenic pigs rescue diabetes and prevent immune rejection in humanized mice. Diabetes 2012; 61:1527–1532.2. YI S, JI M, WU J et al. Adoptive transfer with in vitro expanded human regulatory T cells protects against porcine islet xenograft rejection via interleukin‐10 in humanized mice. Diabetes 2012; 61:1180–1191.
Skeletal muscle mitochondrial dysfunction during chronic obstructive pulmonary disease: central actor and therapeutic target
Authors: Meyer Alain , Zoll Joffrey , Charles Anne Laure , Charloux Anne , de Blay Frédéric , Diemunsch Pierre , Sibilia Jean , Piquard François , Geny Bernard 
Published: February 2013

New Findings
What is the topic of this review?Muscle dysfunction is a common complication and an important independent prognostic factor in chronic obstructive pulmonary disease (COPD).
What advances does it highlight?In COPD patients, the vastus lateralis muscle presents with alterations that include a decrease in mitochondrial density and biogenesis, impaired mitochondrial respiration and coupling, as well as increased mitochondrial production of reactive oxygen species, possibly associated with increased mitochondrial apoptosis. These mitochondrial changes are accessible to conventional therapies, such as exercise and tobacco cessation, but potentially also to innovative management strategies, such as antioxidant treatment and supplementation with polyunsaturated fatty acids. Mitochondrial pathophysiology represents an emerging area of research in muscle dysfunction associated with COPD and has promising therapeutic implications.
Muscle dysfunction is a common complication and an important prognostic factor in chronic obstructive pulmonary disease (COPD). As therapeutic strategies are still needed to treat this complication, gaining more insight into the process that leads to skeletal muscle decline in COPD appears to be an important issue. This review focuses on mitochondrial involvement in limb skeletal muscle alterations (decreased muscle mass, strength, endurance and power and increased fatigue) in COPD. Mitochondria are the main source of energy for the cells; they are involved in production of reactive oxygen species and activate an important pathway that leads to apoptosis. In COPD patients, skeletal muscles are characterized by decreased mitochondrial density and biogenesis, impaired activity and coupling of mitochondrial respiratory chain complexes, increased mitochondrial production of reactive oxygen species and, possibly, increased apoptosis. Of particular interest, a sedentary lifestyle, hypoxia, hypercapnia, tobacco smoking, corticosteroid therapy and, possibly, inflammation participate in this mitochondrial dysfunction, which is accessible to conventional therapies, such as exercise and tobacco cessation, as well as, potentially, to more innovative approaches, such as antioxidant treatment and supplementation with polyunsaturated fatty acids.
Hha Controls Escherichia coli O157:H7 Biofilm Formation by Differential Regulation of Global Transcriptional Regulators FlhDC and CsgD
Authors: Sharma Vijay K. , Bearson Bradley L. 
Published: February 2013

ABSTRACT

Although molecular mechanisms promoting adherence of enterohemorrhagic
Escherichia coli
(EHEC) O157:H7 on epithelial cells are well characterized, regulatory mechanisms controlling biofilm formation are not fully understood. In this study, we demonstrate that biofilm formation in EHEC O157:H7 strain 86-24 is highly repressed compared to that in an isogenic
hha
mutant. The
hha
mutant produced large quantities of biofilm compared to the wild-type strain at 30ï¿½C and 37ï¿½C. Complementation of the
hha
mutant reduced the level of biofilm formation to that of the wild-type strain, indicating that Hha is a negative regulator of biofilm production. While swimming motility and expression of the flagellar gene
fliC
were significantly reduced, the expression of
csgA
(encoding curlin of curli fimbriae) and the ability to bind Congo red were significantly enhanced. The expression of both
fliC
and
csgA
and the phenotypes of motility and curli production affected by these two genes, respectively, were restored to wild-type levels in the complemented
hha
mutant. The
csgA
deletion abolished biofilm formation in the
hha
mutant and wild-type strain, and
csgA
complementation restored biofilm formation to these strains, indicating the importance of
csgA
and curli in biofilm formation. The regulatory effects of Hha on flagellar and curli gene expression appear to occur via the induction and repression of FlhDC and CsgD, as demonstrated by reduced
flhD
and increased
csgD
transcription in the
hha
mutant, respectively. In gel shift assays Hha interacted with
flhDC
and
csgD
promoters. In conclusion, Hha regulates biofilm formation in EHEC O157:H7 by differential regulation of FlhDC and CsgD, the global regulators of motility and curli production, respectively.
Genetic Relationships of Vibrio parahaemolyticus Isolates from Clinical, Human Carrier, and Environmental Sources in Thailand, Determined by Multilocus Sequence Analysis
Authors: Theethakaew Chonchanok , Feil Edward J. , Castillo-Ramï¿½rez Santiago , Aanensen David M. , Suthienkul Orasa , Neil Douglas M. , Davies Robert L. 
Published: February 2013

ABSTRACT

Vibrio parahaemolyticus
is a seafood-borne pathogenic bacterium that is a major cause of gastroenteritis worldwide. We investigated the genetic and evolutionary relationships of 101
V. parahaemolyticus
isolates originating from clinical, human carrier, and various environmental and seafood production sources in Thailand using multilocus sequence analysis. The isolates were recovered from clinical samples (
n
= 15), healthy human carriers (
n
= 18), various types of fresh seafood (
n
= 18), frozen shrimp (
n
= 16), fresh-farmed shrimp tissue (
n
= 18), and shrimp farm water (
n
= 16). Phylogenetic analysis revealed a high degree of genetic diversity within the
V. parahaemolyticus
population, although isolates recovered from clinical samples and from farmed shrimp and water samples represented distinct clusters. The tight clustering of the clinical isolates suggests that disease-causing isolates are not a random sample of the environmental reservoir, although the source of infection remains unclear. Extensive serotypic diversity occurred among isolates representing the same sequence types and recovered from the same source at the same time. These findings suggest that the O- and K-antigen-encoding loci are subject to exceptionally high rates of recombination. There was also strong evidence of interspecies horizontal gene transfer and intragenic recombination involving the
recA
locus in a large proportion of isolates. As the majority of the intragenic recombinational exchanges involving
recA
occurred among clinical and carrier isolates, it is possible that the human intestinal tract serves as a potential reservoir of donor and recipient strains that is promoting horizontal DNA transfer, driving evolutionary change, and leading to the emergence of new, potentially pathogenic strains.
Phylogenetic Delineation of the Novel Phylum Armatimonadetes (Former Candidate Division OP10) and Definition of Two Novel Candidate Divisions
Authors: Lee K. C. Y. , Herbold C. W. , Dunfield P. F. , Morgan X. C. , McDonald I. R. , Stott M. B. 
Published: February 2013

ABSTRACT

Small-subunit (SSU) rRNA gene sequences associated with the phylum
Armatimonadetes
were analyzed using multiple phylogenetic methods, clarifying both the phylum boundary and the affiliation of previously ambiguous groupings. Here we define the
Armatimonadetes
as 10 class-level groups and reclassify two previously associated groups as candidate divisions WS1 and FBP.
Evaluating the Pathogenic Potential of Environmental Escherichia coli by Using the Caenorhabditis elegans Infection Model
Authors: Merkx-Jacques Alexandra , Coors Anja , Brousseau Roland , Masson Luke , Mazza Alberto , Tien Yuan-Ching , Topp Edward 
Published: February 2013

ABSTRACT

The detection and abundance of
Escherichia coli
in water is used to monitor and mandate the quality of drinking and recreational water. Distinguishing commensal waterborne
E. coli
isolates from those that cause diarrhea or extraintestinal disease in humans is important for quantifying human health risk. A DNA microarray was used to evaluate the distribution of virulence genes in 148
E. coli
environmental isolates from a watershed in eastern Ontario, Canada, and in eight clinical isolates. Their pathogenic potential was evaluated with
Caenorhabditis elegans
, and the concordance between the bioassay result and the pathotype deduced by genotyping was explored. Isolates identified as potentially pathogenic on the basis of their complement of virulence genes were significantly more likely to be pathogenic to
C. elegans
than those determined to be potentially nonpathogenic. A number of isolates that were identified as nonpathogenic on the basis of genotyping were pathogenic in the infection assay, suggesting that genotyping did not capture all potentially pathogenic types. The detection of the adhesin-encoding genes
sfaD
,
focA
, and
focG
, which encode adhesins; of
iroN
2
, which encodes a siderophore receptor; of
pic
, which encodes an autotransporter protein; and of
b1432
, which encodes a putative transposase, was significantly associated with pathogenicity in the infection assay. Overall,
E. coli
isolates predicted to be pathogenic on the basis of genotyping were indeed so in the
C. elegans
infection assay. Furthermore, the detection of
C. elegans
-infective environmental isolates predicted to be nonpathogenic on the basis of genotyping suggests that there are hitherto-unrecognized virulence factors or combinations thereof that are important in the establishment of infection.
Changes in Enterococcal Populations and Related Antibiotic Resistance along a Medical Center-Wastewater Treatment Plant-River Continuum
Authors: Leclercq Roland , Oberlï¿½ Kenny , Galopin Sï¿½bastien , Cattoir Vincent , Budzinski Hï¿½lï¿½ne , Petit Fabienne 
Published: February 2013

ABSTRACT

To determine if hospital effluent input has an ecological impact on downstream aquatic environment, antibiotic resistance in
Enterococcus
spp. along a medical center-retirement home-wastewater treatment plant-river continuum in France was determined using a culture-based method. Data on antibiotic consumption among hospitalized and general populations and levels of water contamination by antibiotics were collected. All isolated enterococci were genotypically identified to the species level, tested for
in vitro
antibiotic susceptibility, and typed by multilocus sequence typing. The
erm
(B) and
mef
(A) (macrolide resistance) and
tet
(M) (tetracycline resistance) genes were detected by PCR. Along the continuum, from 89 to 98% of enterococci, according to the sampled site, were identified as
Enterococcus faecium
. All
E. faecium
isolates from hospital and retirement home effluents were multiply resistant to antibiotics, contained
erm
(B) and
mef
(A) genes, and belonged to hospital-adapted clonal complex 17 (CC17). Even though this species remained dominant in the downstream continuum, the relative proportion of CC17 isolates progressively decreased in favor of other subpopulations of
E. faecium
that were more diverse, less resistant to antibiotics, and devoid of the classical macrolide resistance genes and that belonged to various sequence types. Antibiotic concentrations in waters were far below the MICs for susceptible isolates. CC17
E. faecium
was probably selected in the gastrointestinal tract of patients under the pressure of administered antibiotics and then excreted together with the resistance genes in waters to progressively decrease along the continuum.
Rewiring Lactococcus lactis for Ethanol Production
Authors: Solem Christian , Dehli Tore , Jensen Peter Ruhdal 
Published: February 2013

ABSTRACT

Lactic acid bacteria (LAB) are known for their high tolerance toward organic acids and alcohols (R. S. Gold, M. M. Meagher, R. Hutkins, and T. Conway, J. Ind. Microbiol.
10:
45–54, 1992) and could potentially serve as platform organisms for production of these compounds. In this study, we attempted to redirect the metabolism of LAB model organism
Lactococcus lactis
toward ethanol production. Codon-optimized
Zymomonas mobilis
pyruvate decarboxylase (PDC) was introduced and expressed from synthetic promoters in different strain backgrounds. In the wild-type
L. lactis
strain MG1363 growing on glucose, only small amounts of ethanol were obtained after introducing PDC, probably due to a low native alcohol dehydrogenase activity. When the same strains were grown on maltose, ethanol was the major product and lesser amounts of lactate, formate, and acetate were formed. Inactivating the lactate dehydrogenase genes
ldhX
,
ldhB
, and
ldh
and introducing codon-optimized
Z. mobilis
alcohol dehydrogenase (ADHB) in addition to PDC resulted in high-yield ethanol formation when strains were grown on glucose, with only minor amounts of by-products formed. Finally, a strain with ethanol as the sole observed fermentation product was obtained by further inactivating the phosphotransacetylase (PTA) and the native alcohol dehydrogenase (ADHE).
Redundancy among Manganese Peroxidases in Pleurotus ostreatus
Authors: Salame Tomer M. , Knop Doriv , Levinson Dana , Yarden Oded , Hadar Yitzhak 
Published: February 2013

ABSTRACTManganese peroxidases (MnPs) are key players in the ligninolytic system of white rot fungi. InPleurotus ostreatus(the oyster mushroom) these enzymes are encoded by a gene family comprising nine members,mnp1to -9(mnpgenes). Mn2+amendment toP. ostreatuscultures results in enhanced degradation of recalcitrant compounds (such as the azo dye orange II) and lignin. In Mn2+-amended glucose-peptone medium,mnp3,mnp4, andmnp9were the most highly expressedmnpgenes. After 7 days of incubation, the time point at which the greatest capacity for orange II decolorization was observed,mnp3expression and the presence of MnP3 in the extracellular culture fluids were predominant. To determine the significance of MnP3 for ligninolytic functionality in Mn2+-sufficient cultures,mnp3was inactivated via the Δku80strain-basedP. ostreatusgene-targeting system. In Mn2+-sufficient medium, inactivation ofmnp3did not significantly affect expression of nontargeted MnPs or their genes, nor did it considerably diminish the fungal Mn2+-mediated orange II decolorization capacity, despite the significant reduction in total MnP activity. Similarly, inactivation of eithermnp4ormnp9did not affect orange II decolorization ability. These results indicate functional redundancy within theP. ostreatusMnP gene family, enabling compensation upon deficiency of one of its members.
Evidence from Serpula lacrymans that 2,5-Dimethoxyhydroquinone Is a Lignocellulolytic Agent of Divergent Brown Rot Basidiomycetes
Authors: Korripally Premsagar , Timokhin Vitaliy I. , Houtman Carl J. , Mozuch Michael D. , Hammel Kenneth E. 
Published: February 2013

ABSTRACT

Basidiomycetes that cause brown rot of wood are essential biomass recyclers in coniferous forest ecosystems and a major cause of failure in wooden structures. Recent work indicates that distinct lineages of brown rot fungi have arisen independently from ligninolytic white rot ancestors via loss of lignocellulolytic enzymes. Brown rot thus proceeds without significant lignin removal, apparently beginning instead with oxidative attack on wood polymers by Fenton reagent produced when fungal hydroquinones or catechols reduce Fe
3+
in colonized wood. Since there is little evidence that white rot fungi produce these metabolites, one question is the extent to which independent lineages of brown rot fungi may have evolved different Fe
3+
reductants. Recently, the catechol variegatic acid was proposed to drive Fenton chemistry in
Serpula lacrymans
, a brown rot member of the Boletales (D. C. Eastwood et al., Science 333:762-765, 2011). We found no variegatic acid in wood undergoing decay by
S. lacrymans
. We found also that variegatic acid failed to reduce
in vitro
the Fe
3+
oxalate chelates that predominate in brown-rotting wood and that it did not drive Fenton chemistry
in vitro
under physiological conditions. Instead, the decaying wood contained physiologically significant levels of 2,5-dimethoxyhydroquinone, a reductant with a demonstrated biodegradative role when wood is attacked by certain brown rot fungi in two other divergent lineages, the Gloeophyllales and Polyporales. Our results suggest that the pathway for 2,5-dimethoxyhydroquinone biosynthesis may have been present in ancestral white rot basidiomycetes but do not rule out the possibility that it appeared multiple times via convergent evolution.
Global Small RNA Chaperone Hfq and Regulatory Small RNAs Are Important Virulence Regulators in Erwinia amylovora
Authors: Zeng Quan , McNally R. Ryan , Sundin George W. 
Published: February 2013

ABSTRACT

Hfq is a global small RNA (sRNA) chaperone that interacts with Hfq-regulated sRNAs and functions in the posttranscriptional regulation of gene expression. In this work, we identified Hfq to be a virulence regulator in the Gram-negative fire blight pathogen
Erwinia amylovora
. Deletion of
hfq
in
E. amylovora
Ea1189 significantly reduced bacterial virulence in both immature pear fruits and apple shoots. Analysis of virulence determinants in strain Ea1189Δ
hfq
showed that Hfq exerts pleiotropic regulation of amylovoran exopolysaccharide production, biofilm formation, motility, and the type III secretion system (T3SS). Further characterization of biofilm regulation by Hfq demonstrated that Hfq limits bacterial attachment to solid surfaces while promoting biofilm maturation. Characterization of T3SS regulation by Hfq revealed that Hfq positively regulates the translocation and secretion of the major type III effector DspE and negatively controls the secretion of the putative translocator HrpK and the type III effector Eop1. Lastly, 10 Hfq-regulated sRNAs were identified using a computational method, and two of these sRNAs, RprA and RyhA, were found to be required for the full virulence of
E. amylovora
.
Functional Analysis of the Protein Veg, Which Stimulates Biofilm Formation in Bacillus subtilis
Authors: Lei Ying , Oshima Taku , Ogasawara Naotake , Ishikawa Shu 
Published: February 2013

ABSTRACT

Biofilm is a complex aggregate of cells that adhere to each other and produce an extracellular matrix. In
Bacillus subtilis
, an extracellular polysaccharide (EPS) and amyloid fiber (TasA), synthesized by the
epsA
-
epsO
and
tapA
-
sipW
-
tasA
operons, respectively, are the primary components of the extracellular matrix. In the current study, we investigated the functional role of the previously uncharacterized
veg
gene in
B. subtilis
. Overproduction of Veg, a small protein highly conserved among Gram-positive bacteria, stimulated biofilm formation via inducing transcription of the
tapA
-
sipW
-
tasA
operon. Moreover, overproduced Veg restored the impairment of biofilm formation in mutants carrying a deletion of of
sinI
,
slrA
, or
slrR
, encoding an antirepressor of SinR that acts as the master regulator of biofilm formation, while biofilm morphology in the absence of SinR was not affected by either additional
veg
deletion or overproduction, indicating that Veg negatively regulates SinR activity independently of the known antirepressors. Expression of
sinR
was not affected in Veg-overproducing cells, and amounts of SinR were similar in cells expressing different levels of Veg, strongly suggesting that Veg modulates the repressor activity of SinR. Interestingly, the results of
in vivo
pulldown assays of the SinR complex indicate that Veg inhibits the interactions between SinR and SlrR. Based on these findings, we propose that Veg or a Veg-induced protein acts as an antirepressor of SinR to regulate biofilm formation.