bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of Intestinal Intraepithelial Lymphocytes, NK Cells, and NK 1.1+ T Cells in CD45-Deficient Mice
Authors: Martin Steven M. , Mehta Indira K. , Yokoyama Wayne M. , Thomas Matthew L. , Lorenz Robin G. 
Published: April 2014

AbstractThe transmembrane protein tyrosine phosphatase CD45 is differentially required for the development and function of B, T, and NK cells, with mice partially deficient for CD45 having a significant inhibition of T cell, but not NK or B cell, development. CD45-mediated signaling has also been implicated in the development of intrathymic, but not extrathymic, intestinal intraepithelial T lymphocytes (iIELs) in the CD45ex6−/− mouse. As NK1.1+ CD3+ (NK-T) cells can also develop through extrathymic pathways, we have investigated the role of CD45 in NK-T cell development. In mice with a complete absence of CD45 expression (CD45ex9−/−) the NK-T cell population was maintained in the iIEL compartment, but not in the spleen. Functionally, CD45-deficient NK-T cells were unable to secrete IL-4 in response to TCR-mediated signals, a phenotype similar to that of CD45-deficient iIELs, in which in vitro cytokine production was dramatically reduced. Using the CD45ex9−/− mouse strain, we have also demonstrated that only one distinct population of NK-T cells (CD8+) appears to develop normally in the absence of CD45. Interestingly, although an increase in cytotoxic NK cells is seen in the absence of CD45, these NK calls are functionally unable to secrete IFN-γ. In the absence of CD45, a significant population of extrathymically derived CD8αα+ iIELs is also maintained. These results demonstrate that in contrast to conventional T cells, CD45 is not required during the development of CD8+ NK-T cells, NK cells, or CD8αα+ iIELs, but is essential for TCR-mediated function and cytokine production.
Transcriptional Regulation of Intracellular IL-1 Receptor Antagonist Gene by IL-1α in Primary Mouse Keratinocytes
Authors: La Eunhye , Fischer Susan M. 
Published: April 2014

AbstractThe inflammatory cytokine IL-1α mediates inflammatory reactions in skin and up-regulates the expression of other proinflammatory genes. We previously found that IL-1α also increases steady state mRNA levels for intracellular IL-1 receptor antagonist (icIL-1Ra) in primary mouse keratinocytes; however, the mechanism for this was unknown. Here we show that increased expression in primary keratinocytes is due to increased rates of transcription. To study the transcriptional regulation of icIL-1Ra expression induced by IL-1α, we functionally characterized 4.5 kb of the 5′-flanking region of the human icIL-1Ra gene. Deletion analysis showed that regulatory elements were contained in the −598- and −288-bp region upstream of the transcription start site. Then we investigated cis- and trans-acting factors required for icIL-1Ra expression and found that a NF-IL-6 site and a NF-κB site in the icIL-1Ra promoter were responsible for IL-1α-induced icIL-1Ra expression. Moreover, gel shift assays and cotransfection experiments showed that CCAAT/enhancer-binding proteins α, β, and p65 bind to the NF-IL-6 site and NF-κB site, respectively, and functionally trans-activate the icIL-1Ra promoter. Finally, mutational analysis confirmed that these elements were both essential for maximal transcription induced by IL-1α.
Multiple Transcription Factors Regulate the Inducible Expression of the Human Complement Receptor 2 Promoter
Authors: Vereshchagina Lyudmila A. , Tolnay Mate , Tsokos George C. 
Published: April 2014

AbstractComplement receptor 2 (CR2) is regulated at the transcriptional level, but the promoter elements and the transcription factors that bind to them and contribute to its regulation are unknown. After documenting that PMA and cAMP induced the activity of the CR2 promoter by 10-fold, we conducted promoter truncation and mutagenesis experiments, in conjunction with shift assays, to determine the functionally important regions of the promoter and the proteins that bind to them. We identified two regions, separated by ∼900 nucleotides, which together were responsible for inducible promoter activity. Mutagenesis of single promoter elements demonstrated a functional upstream stimulatory factor/E box in the TATA box-proximal region and three equally important, closely spaced, CREB/AP-1 half-sites in the upstream promoter region. The cAMP response element-binding protein (CREB)/AP-1 half-sites bound in vitro Jun and CREB that are induced by protein kinases A and/or C. The 900-nucleotide segment stretching between the above two regions had no functional impact on the induced transcription, and its deletion increased the promoter activity. Finally, a region upstream of the distal site had a repressor activity on CR2 transcription. Moreover, IL-4 induced binding of CREB and AP-1 to the upstream promoter elements and resulted in increased CR2 surface protein expression. These studies have characterized regions of the CR2 promoter and the transcription factors that bind to them and are crucial to induced CR2 expression. Our studies may provide insights to novel approaches to modulate B cell function by regulating CR2 gene transcription.
Characteristics of HIV-1 Nef Regions Containing Multiple CD8+ T Cell Epitopes: Wealth of HLA-Binding Motifs and Sensitivity to Proteasome Degradation
Authors: Choppin Jeannine , Cohen William , Bianco Alberto , Briand Jean-Paul , Connan Francine , Dalod Marc , Guillet Jean-Gérard 
Published: April 2014

AbstractFirst and foremost among the many factors that influence epitope presentation are the degradation of Ag, which results in peptide liberation, and the presence of HLA class I molecules able to present the peptides to T lymphocytes. To define the regions of HIV-1 Nef that can provide multiple T cell epitopes, we analyzed the Nef sequence and determined that there are 73 peptides containing 81 HLA-binding motifs. We tested the binding of these peptides to six common HLA molecules (HLA-A2, -A3, -A24, -B7, -B8, and -B35), and we showed that most of them were efficient binders (54% of motifs), especially peptides associating with HLA-A3, -B7/35, and -B8 molecules. Nef peptides most frequently recognized by T cells of HIV-1-infected individuals were 90–97, 135–143, 71–81, 77–85, 90–100, 73–82, and 128–137. The frequency of T cell recognition was not directly related to the strength of peptide-HLA binding. The generation of Nef epitopes is crucial; therefore, we investigated the digestion by the 20S proteasome of a large peptide, Nef66–100. This fragment was efficiently cleaved, and NH2-terminally extended precursors of epitope 71–81 were recognized by T cells of an HIV-1-infected individual. These results suggest that a high frequency of T cell recognition may depend on proteasome cleavage.
RNA-Dependent Protein Kinase PKR Is Required for Activation of NF-κB by IFN-γ in a STAT1-Independent Pathway
Authors: Deb Amitabha , Haque S. Jaharul , Mogensen Trine , Silverman Robert H. , Williams Bryan R. G. 
Published: April 2014

AbstractThe IFN-inducible dsRNA-activated protein kinase PKR regulates protein synthesis through phosphorylation of eukaryotic initiation factor-2α. It also acts as a signal transducer for transcription factors NF-κB, IFN regulatory factor-1, and activating transcription factor-2. IFN-γ, a pleiotropic cytokine, elicits gene expression by activating the Janus kinase-STAT signaling pathway. IFN-γ can synergize with TNF-α to activate NF-κB in a number of cell lines. Here we show that IFN-γ alone can activate NF-κB, by a Janus kinase-1-mediated, but Stat1-independent, mechanism. NF-κB activation by IFN-γ is associated with degradation of IκB β. The IFN-γ response can be blocked by 2′,5′-oligoadenylate-linked antisense chimeras against PKR mRNA. There was no activation of NF-κB by IFN in PKR-null cells, indicating that PKR is required for IFN-γ signaling to NF-κB.
Positive and Negative Roles of theTrans-Acting T Cell Factor-1 for the Acquisition of Distinct Ly-49 MHC Class I Receptors by NK Cells
Authors: Kunz Béatrice , Held Werner 
Published: April 2014

AbstractMembers of the Ly-49 gene family code for class I MHC-specific receptors that regulate NK cell function. Due to a combinatorial distribution of Ly-49 receptors, NK cells display considerable clonal heterogeneity. The acquisition of one Ly-49 receptor, Ly-49A is strictly dependent on the transcriptional trans-acting factor T cell-specific factor-1 (TCF-1). Indeed, TCF-1 binds to two sites in the Ly-49a promoter and regulates its activity, suggesting that the Ly-49a gene is a direct TCF-1 target. TCF-1 deficiency resulted in the altered usage of additional Ly-49 receptors. We show in this study, using TCF-1 β2-microglobulin double-deficient mice, that these repertoire alterations are not due to Ly-49/MHC class I interactions. Our findings rather suggest a TCF-1-dependent, cell autonomous effect on the acquisition of multiple Ly-49 receptors. Besides reduced receptor usage (Ly-49A and D), we also observed no effect (Ly-49C) and significantly expanded (Ly-49G and I) receptor usage in the absence of TCF-1. These effects did not in all cases correlate with the presence of TCF binding sites in the respective proximal promoter. Therefore, besides TCF-1 binding to the proximal promoter, Ly-49 acquisition may also be regulated by TCF-1 binding to more distant cis-acting elements and/or by regulating the expression of additional trans-acting factors. Consistent with the observed differential, positive or negative role of TCF-1 for Ly-49 receptor acquisition, reporter gene assays revealed the presence of an inducing as well as a repressing TCF site in certain proximal Ly-49 promoters. These findings reveal an important role of TCF-1 for the formation of the NK cell receptor repertoire.
Enhancement of Sindbis Virus Self-Replicating RNA Vaccine Potency by Linkage ofMycobacterium tuberculosisHeat Shock Protein 70 Gene to an Antigen Gene
Authors: Cheng Wen-Fang , Hung Chien-Fu , Chai Chee-Yin , Hsu Keng-Fu , He Liangmai , Rice Charles M. , Ling Morris , Wu T.-C. 
Published: April 2014

AbstractRecently, self-replicating RNA vaccines (RNA replicons) have emerged as an effective strategy for nucleic acid vaccine development. Unlike naked DNA vaccines, RNA replicons eventually cause lysis of transfected cells and therefore do not raise the concern of integration into the host genome. We evaluated the effect of linking human papillomavirus type 16 E7 as a model Ag to Mycobacterium tuberculosis heat shock protein 70 (HSP70) on the potency of Ag-specific immunity generated by a Sindbis virus self-replicating RNA vector, SINrep5. Our results indicated that this RNA replicon vaccine containing an E7/HSP70 fusion gene generated significantly higher E7-specific T cell-mediated immune responses in vaccinated mice than did vaccines containing the wild-type E7 gene. Furthermore, our in vitro studies demonstrated that E7 Ag from E7/HSP70 RNA replicon-transfected cells can be processed by bone marrow-derived dendritic cells and presented more efficiently through the MHC class I pathway than can wild-type E7 RNA replicon-transfected cells. More importantly, the fusion of HSP70 to E7 converted a less effective vaccine into one with significant potency against E7-expressing tumors. This antitumor effect was dependent on NK cells and CD8+ T cells. These results indicated that fusion of HSP70 to an Ag gene may greatly enhance the potency of self-replicating RNA vaccines.
Herpes Simplex Inhibits the Capacity of Lymphoblastoid B Cell Lines to Stimulate CD4+ T Cells
Authors: Barcy Serge , Corey Lawrence 
Published: April 2014

AbstractHSV establish a lifelong persistent infection in their host even among immunocompetent persons. The viruses use a variety of immune evasion strategies, presumably to assist persistent replication in the human host. We have observed that infection of human B lymphoblastoid cells (B-LCL) by HSV resulted in a strong inhibition of their ability to induce CD4+ T cell clone proliferation and cytokine secretion. This inhibitory effect occurs in a variety of both HSV- and HIV-specific clones from three different patients. The inhibition is observed when the Ag is provided either as a soluble protein or as a synthetic peptide and is not associated with detectable down-modulation of the MHC class II molecules or costimulatory molecules. Expression of the HSV-1 unique sequence 1 gene (US1) is necessary and sufficient to induce this inhibition of APC function. US1 gene expression also made B-LCL less susceptible to CD4+ T cell-mediated lysis. These data indicate a novel immune evasion strategy by HSV-1 in which Ag-processing cells that become infected by HSV-1 are inhibited in their ability to induce subsequent CD4+ T cell activation.
Activity of Human IgG and IgA Subclasses in Immune Defense Against Neisseria meningitidis Serogroup B
Authors: Vidarsson Gestur , van der Pol W.-Ludo , van den Elsen Jean M. H. , Vilé Henriëtte , Jansen Marc , Duijs Jacques , Morton H. Craig , Boel Edwin , Daha Mohamed R. , Corthésy Blaise , van de Winkel Jan G. J. 
Published: April 2014

Abstract
Both IgG and IgA Abs have been implicated in host defense against bacterial infections, although their relative contributions remain unclear. We generated a unique panel of human chimeric Abs of all human IgG and IgA subclasses with identical V genes against porin A, a major subcapsular protein Ag of Neisseria meningitidis and a vaccine candidate. Chimeric Abs were produced in baby hamster kidney cells, and IgA-producing clones were cotransfected with human J chain and/or human secretory component. Although IgG (isotypes IgG1–3) mediated efficient complement-dependent lysis, IgA was unable to. However, IgA proved equally active to IgG in stimulating polymorphonuclear leukocyte respiratory burst. Remarkably, although porin-specific monomeric, dimeric, and polymeric IgA triggered efficient phagocytosis, secretory IgA did not. These studies reveal unique and nonoverlapping roles for IgG and IgA Abs in defense against meningococcal infections.
Apoptosis: One of the Mechanisms That Maintains Unresponsiveness of the Intestinal Mucosal Immune System
Authors: Bu Ping , Keshavarzian Ali , Stone David D. , Liu Jianzhong , Le Phong T. , Fisher Susan , Qiao Liang 
Published: April 2014

AbstractIntestinal mucosa is constantly exposed to environmental Ags. Activation of lamina propria (LP) T cells by luminal Ags may lead to the production of inflammatory cytokines and subsequent mucosal inflammation and tissue damage. However, in normal circumstances, LP T cells do not respond to antigenic stimulation. The mechanisms of this unresponsiveness in healthy subjects are not fully understood. In this study, we found by in vivo analysis that, except for T cells in lymph nodules of the mucosa, 15% of LP T cells underwent apoptosis in normal individuals. In contrast, there was a marked reduction in apoptosis of LP T cells in patients with inflammatory bowel disease (Crohn’s disease and ulcerative colitis) and those with specific colitis. Our findings suggest that apoptosis might be a mechanism that turns off mucosal T cell responses to environmental Ags in healthy subjects, and resistance to apoptosis could be an important cause of mucosal immune dysregulation and tissue inflammation in colitis.
Complement Component C3 Is Not Required for Full Expression of Immune Complex Glomerulonephritis in MRL/lprMice
Authors: Sekine Hideharu , Reilly Christopher M. , Molano Ivan D. , Garnier Gérard , Circolo Antonella , Ruiz Philip , Holers V. Michael , Boackle Susan A. , Gilkeson Gary S. 
Published: April 2014

AbstractComplement activation and tissue deposition of complement fragments occur during disease progression in lupus nephritis. Genetic deficiency of some complement components (e.g., Factor B) and infusion of complement inhibitors (e.g., Crry, anti-C5 Ab) protect against inflammatory renal disease. Paradoxically, genetic deficiencies of early components of the classical complement pathway (e.g., C1q, C4, and C2) are associated with an increased incidence of lupus in humans and lupus-like disease in murine knockout strains. Complement protein C3 is the converging point for activation of all three complement pathways and thus plays a critical role in biologic processes mediated by complement activation. To define the role of C3 in lupus nephritis, mice rendered C3 deficient by targeted deletion were backcrossed for eight generations to MRL/lpr mice, a mouse strain that spontaneously develops lupus-like disease. We derived homozygous knockout (C3−/−), heterozygous (C3+/−), and C3 wild-type (C3+/+) MRL/lpr mice. Serum levels of autoantibodies and circulating immune complexes were similar among the three groups. However, there was earlier and significantly greater albuminuria in the C3−/− mice compared with the other two groups. Glomerular IgG deposition was also significantly greater in the C3−/− mice than in the other two groups, although overall pathologic renal scores were similar. These results indicate that C3 and/or activation of C3 is not required for full expression of immune complex renal disease in MRL/lpr mice and may in fact play a beneficial role via clearance of immune complexes.
Impairment of CD8+ T Suppressor Cell Function in Patients with Active Systemic Lupus Erythematosus
Authors: Filaci Gilberto , Bacilieri Sabrina , Fravega Marco , Monetti Monia , Contini Paola , Ghio Massimo , Setti Maurizio , Puppo Francesco , Indiveri Francesco 
Published: April 2014

AbstractAlteration of T cell suppression function has been recognized in patients with systemic lupus erythematosus (SLE). Recently, CD8+ T suppressor lymphocytes (CD8+ Ts) have been generated in vitro by incubating purified CD8+ T cells with IL-2 and GM-CSF. Using this method, we generated CD8+ Ts from patients affected by SLE. No major differences were found in the CD8+ Ts phenotype between SLE patients and healthy subjects. CD8+ Ts from SLE patients with active disease did not inhibit the anti-CD3 mAb-induced proliferation of autologous PBMC, whereas CD8+ Ts from SLE patients in remission exerted an inhibitory activity comparable to normal subjects. The inhibitory effect of CD8+ Ts cells was neither mediated by cytotoxic activity nor by apoptosis induction. Two cytokines, IFN-γ and IL-6, were found to be responsible for the function of CD8+ Ts. In fact, counteraction of CD8+ Ts suppression activity was obtained by blocking IFN-γ with a specific Ab or by inhibiting CD8+ Ts-mediated IL-6 secretion by an antisense oligonucleotide. Interestingly, CD8+ Ts from SLE patients showed a peculiar cytokine pattern characterized by an impaired secretion of IL-6 and an increased secretion of IL-12. Thus, it appears that an altered balance between inhibitory (IL-6) and stimulatory (IL-12) cytokines might be responsible for the functional impairment of CD8+ Ts in SLE patients.
Cutting Edge: Cellular Fas-Associated Death Domain-Like IL-1-Converting Enzyme-Inhibitory Protein Protects Germinal Center B Cells from Apoptosis During Germinal Center Reactions
Authors: van Eijk Marco , Medema Jan Paul , de Groot Cornelis 
Published: April 2014

Abstract
During germinal center (GC) reactions, follicular dendritic cells are believed to select memory B lymphocytes by switching off apoptosis in the successfully binding B cells. The cellular signals involved in this process are largely unknown. Here, we show that GC B lymphocytes have a long isoform of the cellular homologue of the viral Fas-associated death domain-like IL-1-converting enzyme-like inhibitory protein (cFLIPL), which is capable of inhibiting death receptor-induced caspase activation. In isolated GC B cells, cFLIPL decays rapidly even without Fas ligation, and this results in activation of caspase activity and apoptosis. Contact with follicular dendritic cells prevents cFLIPL degradation and blocks all signs of apoptosis, even in the presence of anti-Fas Abs. cFLIPL expression is sustained by CD40 ligation as well, suggesting that at least at some stage of the GC reaction activated T cells may help selected B cells to leave the follicular dendritic cell network without becoming apoptotic.
Low-Level Monocyte Chemoattractant Protein-1 Stimulation of Monocytes Leads to Tumor Formation in Nontumorigenic Melanoma Cells
Authors: Nesbit Mark , Schaider Helmut , Miller Thomas H. , Herlyn Meenhard 
Published: April 2014

AbstractTumors commonly produce chemokines for recruitment of host cells, but the biological significance of tumor-infiltrating inflammatory cells, such as monocytes/macrophages, for disease outcome is not clear. Here, we show that all of 30 melanoma cell lines secreted monocyte chemoattractant protein-1 (MCP-1), whereas normal melanocytes did not. When low MCP-1-producing melanoma cells from a biologically early, nontumorigenic stage were transduced to overexpress the MCP-1 gene, tumor formation depended on the level of chemokine secretion and monocyte infiltration; low-level MCP-1 secretion with modest monocyte infiltration resulted in tumor formation, whereas high secretion was associated with massive monocyte/macrophage infiltration into the tumor mass, leading to its destruction within a few days after injection into mice. Tumor growth stimulated by monocytes/macrophages was due to increased angiogenesis. Vessel formation in vitro was inhibited with mAbs against TNF-α, which, when secreted by cocultures of melanoma cells with human monocytes, induced endothelial cells under collagen gels to form branching, tubular structures. These studies demonstrate that the biological effects of tumor-derived MCP-1 are biphasic, depending on the level of secretion. This correlates with the degree of monocytic cell infiltration, which results in increased tumor vascularization and TNF-α production.
Mechanism of Melphalan-Induced B7-1 Gene Expression in P815 Tumor Cells
Authors: Donepudi Manjula , Raychaudhuri Pradip , Bluestone Jeffrey A. , Mokyr Margalit B. 
Published: April 2014

AbstractWe have previously shown that exposure of P815 tumor cells to melphalan (l-phenylalanine mustard; l-PAM) leads to up-regulation of B7-1 surface expression, and this l-PAM-induced up-regulation requires de novo RNA synthesis and is associated with accumulation of B7-1 mRNA. Here we show that the effect of l-PAM on B7-1 surface expression can be mimicked by exposing P815 tumor cells to oxidative stress but not to heat shock. Moreover, the antioxidant N-acetyl-l-cysteine prevented the l-PAM-induced accumulation of B7-1 mRNA in P815 tumor cells, suggesting that reactive oxygen species are involved in the transcriptional regulation of l-PAM-induced B7-1 gene expression. Although AP-1 and NF-κB are regarded as redox-sensitive transcription factors and the promoter/enhancer region of the B7-1 gene contains an AP-1 and an NF-κB binding site, exposure of P815 tumor cells to l-PAM led to rapid and transient activation only of NF-κB, but not AP-1, that bound specifically to a probe containing the respective binding site in the murine or human B7-1 gene. Moreover, exposure of P815 tumor cells to a cell-permeable peptide that selectively inhibits NF-κB activation by blocking the activation of the IκB-kinase complex was found to inhibit the l-PAM-induced B7-1 mRNA accumulation, indicating that NF-κB activation is essential for the l-PAM-induced B7-1 gene expression. Taken together, these results indicate that l-PAM leads to activation of B7-1 gene expression by activating NF-κB via a pathway that involves reactive oxygen species.