bluuebunny/crossref_metadata_2025_split huggingface dataset:
Escherichia coliNissle 1917 Distinctively Modulates T-Cell Cycling and Expansion via Toll-Like Receptor 2 Signaling
Authors: Sturm Andreas , Rilling Klaus , Baumgart Daniel C. , Gargas Konstantinos , Abou-Ghazalé Tay , Raupach Bärbel , Eckert Jana , Schumann Ralf. R. , Enders Corinne , Sonnenborn Ulrich , Wiedenmann Bertram , Dignass Axel U. 
Published: February 2005

ABSTRACTAlthough the probioticEscherichia colistrain Nissle 1917 has been proven to be efficacious for the treatment of inflammatory bowel diseases, the underlying mechanisms of action still remain elusive. The aim of the present study was to analyze the effects ofE. coliNissle 1917 on cell cycling and apoptosis of peripheral blood and lamina propria T cells (PBT and LPT, respectively). Anti-CD3-stimulated PBT and LPT were treated withE. coliNissle 1917-conditioned medium (E. coliNissle 1917-CM) or heat-inactivatedE. coliNissle 1917. Cyclin B1, DNA content, and caspase 3 expression were measured by flow cytometry to assess cell cycle kinetics and apoptosis. Protein levels of several cell cycle and apoptosis modulators were determined by immunoblotting, and cytokine profiles were determined by cytometric bead array.E. coliNissle 1917-CM inhibits cell cycling and expansion of peripheral blood but not mucosal T cells. Bacterial lipoproteins mimicked the effect ofE. coliNissle 1917-CM; in contrast, heat-inactivatedE. coliNissle 1917, lipopolysaccharide, or CpG DNA did not alter PBT cell cycling.E. coliNissle 1917-CM decreased cyclin D2, B1, and retinoblastoma protein expression, contributing to the reduction of T-cell proliferation.E. coliNissle 1917 significantly inhibited the expression of interleukin-2 (IL-2), tumor necrosis factor α, and gamma interferon but increased IL-10 production in PBT. Using Toll-like receptor 2 (TLR-2) knockout mice, we further demonstrate that the inhibition of PBT proliferation byE. coliNissle 1917-CM is TLR-2 dependent. The differential reaction of circulating and tissue-bound T cells towardsE. coliNissle 1917 may explain the beneficial effect ofE. coliNissle 1917 in intestinal inflammation.E. coliNissle 1917 may downregulate the expansion of newly recruited T cells into the mucosa and limit intestinal inflammation, while already activated tissue-bound T cells may eliminate deleterious antigens in order to maintain immunological homeostasis.
Effect of Mutations in the Human Immunoglobulin A1 (IgA1) Hinge on Its Susceptibility to Cleavage by Diverse Bacterial IgA1 Proteases
Authors: Senior Bernard W. , Woof Jenny M. 
Published: February 2005

ABSTRACTComponents of the human immunoglobulin A1 (IgA1) hinge governing sensitivity to cleavage by bacterial IgA1 proteases were investigated. Recombinant antibodies with distinct hinge mutations were constructed from a hybrid comprised of human IgA2 bearing half of the human IgA1 hinge region. This hybrid antibody and all the mutant antibodies derived from it were resistant to cleavage by the IgA1 proteases fromStreptococcus oralisandStreptococcus mitisbiovar 1 strains but were cleaved to various degrees by those ofStreptococcus pneumoniae, someStreptococcus sanguisstrains, and the type 1 and 2 IgA1 proteases ofHaemophilus influenzae,Neisseria meningitidis, andNeisseria gonorrhoeae. Remarkably, those proteases that cleave a Pro-Ser peptide bond in the wild-type IgA1 hinge were able to cleave mutant antibodies lacking a Pro-Ser peptide bond in the hinge, and those that cleave a Pro-Thr peptide bond in the wild-type IgA1 hinge were able to cleave mutant antibodies devoid of a Pro-Thr peptide bond in the hinge. Thus, the enzymes can cleave alternatives to their preferred postproline peptide bond when such a bond is unavailable. Peptide sequence analysis of a representative antibody digestion product confirmed this conclusion. The presence of a cleavable peptide bond near the CH2 end of the hinge appeared to result in greater cleavage than if the scissile bond was at the CH1 end of the hinge. Proline-to-serine substitution at residue 230 in a hinge containing potentially cleavable Pro-Ser and Pro-Thr peptide bonds increased the resistance of the antibody to cleavage by many IgA1 proteases.
Gingipains fromPorphyromonas gingivalisW83 Induce Cell Adhesion Molecule Cleavage and Apoptosis in Endothelial Cells
Authors: Sheets Shaun M. , Potempa Jan , Travis James , Casiano Carlos A. , Fletcher Hansel M. 
Published: February 2005

ABSTRACTThe presence ofPorphyromonas gingivalisin the periodontal pocket and the high levels of gingipain activity detected in gingival crevicular fluid could implicate a role for gingipains in the destruction of the highly vascular periodontal tissue. To explore the effects of these proteases on endothelial cells, we exposed bovine coronary artery endothelial cells and human microvascular endothelial cells to gingipain-active extracellular protein preparations and/or purified gingipains fromP. gingivalis. Treated cells exhibited a rapid loss of cell adhesion properties that was followed by apoptotic cell death. Cleavage of N- and VE-cadherin and integrin β1 was observed in immunoblots of cell lysates. There was a direct correlation between the kinetics of cleavage of N- and VE-cadherin and loss of cell adhesion properties. Loss of cell adhesion, as well as N- and VE-cadherin and integrin β1 cleavage, could be inhibited or significantly delayed by preincubation ofP. gingivalisW83 gingipain-active extracellular extracts with the cysteine protease inhibitorNα-p-tosyl-l-lysine chloromethylketone. Furthermore, purified gingipains also induced endothelial cell detachment and apoptosis. Apoptosis-associated events, including annexin V positivity, caspase-3 activation, and cleavage of the caspase substrates poly(ADP-ribose) polymerase and topoisomerase I (Topo I), were observed in endothelial cells after detachment. All of the effects observed were correlated with the different levels of cysteine-dependent proteolytic activity of the extracts tested. Taken together, these results indicate that gingipains fromP. gingivaliscan alter cell adhesion molecules and induce endothelial cell death, which could have implications for the pathogenicity of this organism.
A Live and InactivatedChlamydia trachomatisMouse Pneumonitis Strain Induces the Maturation of Dendritic Cells That Are Phenotypically and Immunologically Distinct
Authors: Rey-Ladino Jose , Koochesfahani Kasra M. , Zaharik Michelle L. , Shen Caixia , Brunham Robert C. 
Published: February 2005

ABSTRACTThe intracellular bacterial pathogenChlamydia trachomatisis a major cause of sexually transmitted disease worldwide. While protective immunity does appear to develop following natural chlamydial infection in humans, early vaccine trials using heat-killedC. trachomatisresulted in limited and transient protection with possible enhanced disease during follow-up. Thus, immunity following natural infection with live chlamydia may differ from immune responses induced by immunization with inactivated chlamydia. To study this differing immunology, we used murine bone marrow-derived dendritic cells (DC) to examine DC maturation and immune effector function induced by live and UV-irradiatedC. trachomatiselementary bodies (live EBs and UV-EB, respectively). DC exposed to live EBs acquired a mature DC morphology; expressed high levels of major histocompatibility complex (MHC) class II, CD80, CD86, CD40, and ICAM-1; produced elevated amounts of interleukin-12 and tumor necrosis factor alpha; and were efficiently recognized byChlamydia-specific CD4+T cells. In contrast, UV-EB-pulsed DC expressed low levels of CD40 and CD86 but displayed high levels of MHC class II, ICAM-1, and CD80; secreted low levels of proinflammatory cytokines; and exhibited reduced recognition byChlamydia-specific CD4+T cells. Adoptive transfer of live EB-pulsed DC was more effective than that of UV-EB-pulsed DC at protecting mice against challenge with liveC. trachomatis. The expression of DC maturation markers and immune protection induced by UV-EB could be significantly enhanced by costimulation of DC ex vivo with UV-EB and oligodeoxynucleotides containing cytosine phosphate guanosine; however, the level of protection was significantly less than that achieved by using DC pulsed ex vivo with viable EBs. Thus, exposure of DC to live EBs results in a mature DC phenotype which is able to promote protective immunity, while exposure to UV-EB generates a semimature DC phenotype with less protective potential. This result may explain in part the differences in protective immunity induced by natural infection and immunization with whole inactivated organisms and is relevant to rational chlamydia vaccine design strategies.
ThePseudomonas aeruginosaQuorum-Sensing MoleculeN-3-(Oxododecanoyl)-l-Homoserine Lactone Inhibits T-Cell Differentiation and Cytokine Production by a Mechanism Involving an Early Step in T-Cell Activation
Authors: Ritchie A. J. , Jansson A. , Stallberg J. , Nilsson P. , Lysaght P. , Cooley M. A. 
Published: February 2005

ABSTRACTThePseudomonas aeruginosaquorum-sensing moleculeN-3-(oxododecanoyl)-l-homoserine lactone (OdDHL) has been reported to have immunomodulatory activity in several systems, although the mechanism of that activity remains to be fully characterized. We demonstrate here, using a defined in vitro model of antigen responses by T-cell receptor (TCR)-transgenic mouse splenic CD4 T cells, that the effect of OdDHL on activation and cytokine production is complete within 4 h of antigen or mitogen stimulation and does not depend on the insertion of OdDHL in the cell membrane, despite a previous report that immunosuppression by homoserine lactones required a minimum acyl chain length of 11 carbons (S. R. Chhabra, C. Harty, D. S. W. Hooi, M. Daykin, B. W. Bycroft, P. Williams, and D. Pritchard, J. Med. Chem.46:97-104, 2003). We also demonstrate that while OdDHL can have toxic effects on nonlymphoid leukocytes, it does not induce significant cell death in T cells at the concentrations (≤10 μM) used in these experiments. In addition, we show that primary and secondary antigen-specific cytokine responses are equally susceptible to inhibition by OdDHL and that the compound inhibits the differentiation of both Th1 and Th2 cells. However, the precise balance of cytokine production by CD4 T cells stimulated in the presence of OdDHL varies with both the antigen concentration and its affinity for the transgenic TCR. Thus, conflicting reports of the nature of the immunosuppression by OdDHL may be due in part to the differences in antigen affinity and concentration in different models.
Roles of Cell Adhesion and Cytoskeleton Activity in
Entamoeba histolytica
Pathogenesis: a Delicate Balance
Authors: Tavares Paulo , Rigothier Marie-Christine , Khun Huot , Roux Pascal , Huerre Michel , Guillén Nancy 
Published: February 2005

ABSTRACT

The protozoan parasite
Entamoeba histolytica
colonizes the human large bowel. Invasion of the intestinal epithelium causes amoebic colitis and opens the route for amoebic liver abscesses. The parasite relies on its dynamic actomyosin cytoskeleton and on surface adhesion molecules for dissemination in the human tissues. Here we show that the galactose/
N
-acetylgalactosamine (Gal/GalNAc) lectin clusters in focal structures localized in the region of
E. histolytica
that contacts monolayers of enterocytes. Disruption of myosin II activity impairs the formation of these structures and renders the trophozoites avirulent for liver abscess development. Production of the cytoplasmic domain of the
E. histolytica
Gal/GalNAc lectin in engineered trophozoites causes reduced adhesion to enterocytes. Intraportal delivery of these parasites to the liver leads to the formation of a large number of small abscesses with disorganized morphology that are localized in the vicinity of blood vessels. The data support a model for invasion in which parasite motility is essential for establishment of infectious foci, while the adhesion to host cells modulates the distribution of trophozoites in the liver and their capacity to migrate in the hepatic tissue.
Selection of Resistance in Protease Inhibitor-Experienced, Human Immunodeficiency Virus Type 1-Infected Subjects Failing Lopinavir- and Ritonavir-Based Therapy: Mutation Patterns and Baseline Correlates
Authors: Mo Hongmei , King Martin S. , King Kathryn , Molla Akhteruzzaman , Brun Scott , Kempf Dale J. 
Published: February 2005

ABSTRACTThe selection of in vivo resistance to lopinavir was characterized by analyzing the longitudinal isolates from 54 protease inhibitor-experienced subjects who either experienced incomplete virologic response or viral rebound subsequent to initial response while on treatment with lopinavir-ritonavir in Phase II and III studies. The evolution of incremental resistance to lopinavir (emergence of new mutation[s] and/or at least a twofold increase in phenotypic resistance compared to baseline isolates) was highly dependent on the baseline phenotype and genotype. Among the subjects demonstrating evolution of lopinavir resistance, mutations at positions 82, 54, and 46 in human immunodeficiency virus protease emerged frequently, suggesting that these mutations are important for conferring high-level resistance. Less common mutations, such as L33F, I50V, and V32I together with I47V/A, were also selected; however, new mutations at positions 84, 90, and 71 were not observed. The emergence of incremental resistance contrasts greatly with the low incidence of resistance observed after initiating lopinavir-ritonavir therapy in antiretroviral-naive patients, suggesting that partial resistance accumulated during prior protease inhibitor therapy can compromise the genetic barrier to resistance to lopinavir-ritonavir. The emergence of incremental resistance was uncommon in subjects whose baseline isolates contained eight or more mutations associated with lopinavir resistance and/or displayed >60-fold-reduced susceptibility to lopinavir, providing insight into suitable upper genotypic and phenotypic breakpoints for lopinavir-ritonavir.
Increased Epitope-Specific CD8+T Cells Prevent Murine Coronavirus Spread to the Spinal Cord and Subsequent Demyelination
Authors: MacNamara Katherine C. , Chua Ming Ming , Nelson Peter T. , Shen Hao , Weiss Susan R. 
Published: February 2005

ABSTRACTCD8+T cells are important for clearance of neurotropic mouse hepatitis virus (MHV) strain A59, although their possible role in A59-induced demyelination is not well understood. We developed an adoptive-transfer model to more clearly elucidate the role of virus-specific CD8+T cells during the acute and chronic phases of infection with A59 that is described as follows. C57BL/6 mice were infected with a recombinant A59 virus expressing the gp33 epitope, an H-2Db-restricted CD8+T-cell epitope encoded in the glycoprotein of lymphocytic choriomeningitis virus, as a fusion with the enhanced green fluorescent protein (RA59-gfp/gp33). P14 splenocytes (transgenic for a T-cell receptor specific for the gp33 epitope) were transferred at different times pre- and postinfection (p.i.). Adoptive transfer of P14 splenocytes 1 day prior to infection with RA59-gfp/gp33, but not control virus lacking the gp33 epitope, RA59-gfp, reduced weight loss and viral replication and spread in the brain and to the spinal cord. Furthermore, demyelination was significantly reduced compared to that in nonrecipients. However, when P14 cells were transferred on day 3 or 5 p.i., no difference in acute or chronic disease was observed compared to that in nonrecipients. Protection in mice receiving P14 splenocytes prior to infection correlated with a robust gp33-specific immune response that was not observed in mice receiving the later transfers. Thus, an early robust CD8+T-cell response was necessary to reduce virus replication and spread, specifically to the spinal cord, which protected against demyelination in the chronic phase of the disease.
Nuclear Localization of Japanese Encephalitis Virus Core Protein Enhances Viral Replication
Authors: Mori Yoshio , Okabayashi Tamaki , Yamashita Tetsuo , Zhao Zijiang , Wakita Takaji , Yasui Kotaro , Hasebe Futoshi , Tadano Masayuki , Konishi Eiji , Moriishi Kohji , Matsuura Yoshiharu 
Published: February 2005

ABSTRACT

Japanese encephalitis virus (JEV) core protein was detected in both the nucleoli and cytoplasm of mammalian and insect cell lines infected with JEV or transfected with the expression plasmid of the core protein. Mutation analysis revealed that Gly
42
and Pro
43
in the core protein are essential for the nuclear and nucleolar localization. A mutant M4243 virus in which both Gly
42
and Pro
43
were replaced by Ala was recovered by plasmid-based reverse genetics. In C6/36 mosquito cells, the M4243 virus exhibited RNA replication and protein synthesis comparable to wild-type JEV, whereas propagation in Vero cells was impaired. The mutant core protein was detected in the cytoplasm but not in the nucleus of either C6/36 or Vero cell lines infected with the M4243 virus. The impaired propagation of M4243 in mammalian cells was recovered by the expression of wild-type core protein in
trans
but not by that of the mutant core protein. Although M4243 mutant virus exhibited a high level of neurovirulence comparable to wild-type JEV in spite of the approximately 100-fold-lower viral propagation after intracerebral inoculation to 3-week-old mice of strain Jcl:ICR, no virus was recovered from the brain after intraperitoneal inoculation of the mutant. These results indicate that nuclear localization of JEV core protein plays crucial roles not only in the replication in mammalian cells in vitro but also in the pathogenesis of encephalitis induced by JEV in vivo.
Importin-α Promotes Passage through the Nuclear Pore Complex of Human Immunodeficiency Virus Type 1 Vpr
Authors: Kamata Masakazu , Nitahara-Kasahara Yuko , Miyamoto Yoichi , Yoneda Yoshihiro , Aida Yoko 
Published: February 2005

ABSTRACT

Viral protein R (Vpr) of human immunodeficiency virus type 1 has potent karyophilic properties, but details of the mechanism by which it enters the nucleus remain to be clarified. We reported previously that two regions, located between residues 17 and 34 (αH1) and between residues 46 and 74 (αH2), are indispensable for the nuclear localization of Vpr. Here, we reveal that a chimeric protein composed of the nuclear localization signal of Vpr, glutathione
S
-transferase, and green fluorescent protein was localized at the nuclear envelope and then entered the nucleus upon addition of importin-α. An in vitro transport assay using a series of derivatives of importin-α demonstrated that the carboxyl terminus was required for this nuclear import process. We also showed that Vpr interacts with importin-α through αH1 and αH2; only the interaction via αH1 is indispensable for the nuclear entry of Vpr. These observations indicate that importin-α functions as a mediator for the nuclear entry of Vpr.
Role of the Conserved Nucleotide Mismatch within 3′- and 5′-Terminal Regions of Bunyamwera Virus in Signaling Transcription
Authors: Barr John N. , Wertz Gail W. 
Published: February 2005

ABSTRACT

Bunyamwera virus
(BUNV) is the prototype of the
Bunyaviridae
family of tri-partite negative-sense RNA viruses. The three BUNV segments possess 3′ and 5′ nontranslated regions (NTRs) that signal two RNA synthesis activities: (i) transcription to generate mRNAs and (ii) replication to generate antigenomes that are replicated to yield further genomes. While the genome acts as a template for synthesis of both transcription and replication products, the antigenome allows synthesis of only replication products, with mRNAs being undetectable. Here, we investigate the basis for the fundamentally different signaling abilities of genomic and antigenomic strands. We show that the identity of only nucleotide position 9 within the genomic 3′ NTR is critical for the different RNA synthesis characteristics of genomic and antigenomic strands, thus identifying this nucleotide as an essential component of the transcription promoter. This nucleotide is distinctive, as it interrupts an unbroken run of conserved complementary nucleotides within the 3′ and 5′ NTRs of all three segments. Our results show that the conserved mismatched arrangement of this nucleotide plays no detectable role in signaling transcription. Instead, we show that the transcription-signaling ability of this position is entirely dependent on its nucleotide identity. We further show that while a U residue at 3′ position 9 is strongly preferred for transcription activity in the context of the genomic promoter, it does not signal transcription in the context of the antigenomic promoter. Therefore, our results show that the identity of 3′ position 9 is crucial for signaling BUNV transcription; however, it is not the sole determinant.
BFRF1 of Epstein-Barr Virus Is Essential for Efficient Primary Viral Envelopment and Egress
Authors: Farina Antonella , Feederle Regina , Raffa Salvatore , Gonnella Roberta , Santarelli Roberta , Frati Luigi , Angeloni Antonio , Torrisi Maria Rosaria , Faggioni Alberto , Delecluse Henri-Jacques 
Published: February 2005

ABSTRACT
The molecular mechanisms that underlie maturation and egress of Epstein-Barr virus (EBV) virions are only partially characterized. We have recently shown that the BFRF1 gene, the EBV positional homolog of herpes simplex virus type 1 and pseudorabies virus UL34, is expressed early during EBV lytic replication and that it is found predominantly on the nuclear membrane (A. Farina, R. Santarelli, R. Gonnella, R. Bei, R. Muraro, G. Cardinali, S. Uccini, G. Ragona, L. Frati, A. Faggioni, and A. Angeloni, J. Virol. 74:3235-3244, 2000). These data suggest that the BFRF1 protein might be involved in viral primary envelopment. To precisely determine the function of this protein, we have constructed an EBV mutant devoid of the BFRF1 gene (BFRF1-KO). 293 cells carrying BFRF1-KO showed no differences in comparison with wild-type EBV in terms of DNA lytic replication or expression of late viral proteins upon induction of the lytic cycle. However, binding assays and infection experiments using cell lines or human cord blood lymphocytes showed a clear reduction in the viral mutant titers. Complementation experiments with BFRF1-KO and a BFRF1 expression vector restored viral titers to levels similar to those for the wild-type control, showing that the modifications that we introduced were limited to the BFRF1 gene. Electron microscopic observations showed that the reduction in viral titers was due to sequestration of EBV nucleocapsids in the nuclei of lytically induced cells. This suggests that BFRF1 is involved in transport of the maturing virion across the nuclear membrane. This hypothesis was further supported by the observation that BFRF1 is present in maturing intracellular virions but not in their extracellular counterparts. This implies that BFRF1 is a key protein for EBV maturation.