bluuebunny/crossref_metadata_2025_split huggingface dataset:
Encounter with antigen-specific CD4 T cells promotes down-regulation of MHC-II in Dendritic cells (106.18)
Authors: Furuta Kazuyuki , Ishido Satoshi , Roche Paul 
Published: January 2023

Abstract
Major histocompatibility complex class II molecules (MHC-II) on dendritic cells (DCs) present antigenic peptides to CD4 T cells. MHC-II and T cell receptor (TCR)-mediated DC-T cell interactions induce activation and proliferation of naïve CD4 T cells. The fate of MHC-II molecules after engagement with TCR has not been extensively studied. In this study we investigated the effects of engagement of cell surface MHC-II with TCR. By incubating DCs with T cells, we found that activated CD4 T cells induced degradation of cell surface MHC-II in an antigen-specific manner. T cell engagement-induced degradation of MHC-II was also mimicked by crosslinking of MHC-II by anti-MHC-II mAb. After MHC-II crosslinking, clustering and endocytosis of MHC-II were induced and MHC-II was transported to lysosomes and degraded. MHC-II clustering and endocytosis were inhibited by cell surface cholesterol-depletion using methyl β-cyclodextrin (MβCD). Although ubiquitination is known to regulate cell surface expression of MHC-II in DCs, by using ubiquitination site-deficient MHC-II mutant mice we found that ubiquitination was not required for crosslinking induced MHC-II degradation. Finally, we found that crosslinking of MHC-II on DCs inhibited their ability to stimulate additional naïve CD4 T cells. These results demonstrate that CD4 T cells promote the down-regulation of MHC-II and limit antigen presentation by inducing endocytosis and degradation of MHC-II in DCs.
Gauging the contribution of endogenous MHCII pathways to influenza-specific CD4+ T cell responses (106.32)
Authors: Miller Michael , Luckashenak Nancy , Eisenlohr Laurence 
Published: January 2023

Abstract
The current paradigm for MHC Class II peptide generation holds that exogenous antigen enters the endosomal/lysosomal pathway, where it is processed and presented on the cell surface for presentation to CD4+ T cells. Increasing evidence from our lab and others has elucidated pathways that process endogenous proteins for presentation on MHC Class II and operate exclusively during live infection. Despite this, the components of these pathways, the prevalence of such epitopes, and their general contribution to the immune response remain poorly characterized. Using an IFN-γ-ELISpot assay, we screened a peptide library of the flu proteome to identify potential endogenous CD4+ epitopes generated following live or UV-inactivated virus priming. The differences in specificities were striking, with “live only” hits compromising a major fraction of the response and mapping to both structural and non-structural proteins. Experiments are ongoing to identify those epitopes that can be strictly categorized as endogenous, and to identify cellular components (proteasome, TAP, H-2M,…) that contribute to their generation. A comprehensive understanding of endogenous MHCII epitopes and their corresponding presentation pathways could contribute substantially to improved vaccine design and efficacy.
Aminoglycoside-induced readthrough of stop codons in vivo elicits presentation of novel immunogenic MHC class I epitopes . (106.39)
Authors: Robinson Tara , Zook Matthew , Goodenough Elliot , Nelson Chad , Flanigan Kevin , Atkins John , Howard Michael , Eisenlohr Laurence 
Published: January 2023

Abstract
Aminoglycoside antibiotics are known to induce stop codon readthrough in eukaryotic cells, and thus hold potential for the treatment of genetic diseases caused by nonsense mutations. A potential consequence of aminoglycoside treatment is the translation of 3’ noncoding regions and generation of major histocompatibiltiy complex (MHC)-restricted neoepitopes, a potential cause of autoimmune reactivity. Here we explored the impact of aminoglycoside-induced readthough on the production of MHC class I binding peptides. Firstly, we developed a panel of recombinant vaccinia viruses in which expression of a MHC class I binding peptide depends upon stop codon readthrough. Both in vitro and in vivo studies indicated that gentamicin induces activating levels of epitope with the magnitude of the response strongly influenced by identity of the stop codon and the surrounding context in agreement with a previously determined hierarchy. Secondly, we treated uninfected cells with gentamicin to assess the level of aminoglycoside-induced readthrough on native stop codons. HPLC analysis revealed a small number of differences in the peak profiles. Further analysis will be done with mass spectrometry to determine the identity of these epitopes, and where they are located in the mouse genome. The data from these and future studies can be used determine the extent to which stop codon readthrough occurs, and the implications for eliciting autoimmunity.
Variable processing and presentation of HIV epitopes in HIV-infectable cell subsets (106.8)
Authors: Dinter Jens , Gourdain Pauline , Lai Nicole , Shimada Mariko , Duong Ellen , Le Gall Sylvie 
Published: January 2023

Abstract
HIV-specific CD8 T cells (CTL) play a major role in reducing viral load in acute HIV infection and in the spontaneous control of HIV viremia. HIV infects CD4 T cells, monocytes, macrophages and dendritic cells. Whether these subsets have equivalent capacity to produce and present MHC-I restricted epitopes is unknown. We analyzed the effect of TLR agonist-mediated maturation on the processing and presentation of antigens in monocyte-derived dendritic cells (DC) and macrophages (MP). LPS-induced maturation decreased significantly the proteasomal tryptic activity and lysosomal activities in DC whereas in mature MP these activities were increased. Using cytosolic extracts of DC and MP as a source of peptidases we showed by mass spectrometry that degradation of 3-ISW9 in LPS-matured DC yielded 2-fold more epitope HLA-B57-restricted ISW9 than in immature DC. Using recombinant p24 as an exogenous antigen cross-presented by DC or MP expressing HLA-B57 we observed reduced killing of cells by ISW9-specific CTL compared to TW10- or KF11-specific CTL. The lower ISW9-specific killing of target cells was partly rescued by preincubation of cells with protease inhibitor, suggesting that lower cross-presentation may be due to higher intracellular degradation of ISW9. Differences in antigen processing activities in DC and MP upon maturation, and differences in HIV sequences sensitivity to intracellular degradation may affect the production and presentation of HIV epitopes to CTL.
IRF8 Interacts with the BCL6 Co-repressor, BCOR (109.5)
Authors: Yoon Jeong Heon , Feng Jianxun , Morse III Herbert 
Published: January 2023

Abstract
BCOR has been discovered as a BCL-6 interacting co-repressor, but little is known about its biological activities in normal B cell development and function. Previously, we found that the interferon regulatory factor 8 (IRF8), also known as interferon consensus sequence-binding protein, ICSBP, directly targets a large number of genes in germinal center (GC) B cells including BCL6. In this study, we screened potential binding partners of IRF8 using a retrovirus-based protein complementation assay in a mouse pre-B cell line. We found that IRF8 interacts directly with BCOR and the alpha helical region of IRF8 is required for this interaction. Using a siRNA-mediated IRF8 knockdown mouse B cell lymphoma cell line, we showed that IRF8 represses BCOR and enhances BCL6 transcription. Taken together, these data suggest that a complex comprised of BCOR-IRF8 modulates BCL6 associated transcriptional regulation of B cell function. Additional studies to evaluate the possible role of BCOR-IRF8 complex are in progress.
Antigen availability is a critical determinant of in vivo CD8+ T cell-dendritic cell interaction kinetics and initiates effector/memory fate decisions (110.21)
Authors: Henrickson Sarah , Senman Balimkiz , Quigley Michael , Alexe Gabriela , Stutte Susanne , Jesneck Jonathan , Iannacone Matteo , Flynn Michael , Imam Sabrina , Mazo Irina , Haining William , von Andrian Ulrich 
Published: January 2023

Abstract
Naïve CD8+ T cells are activated through interactions with antigen (Ag) bearing dendritic cells (DCs) in lymph nodes (LNs). Multiphoton intravital microscopy (MP-IVM) of LNs has demonstrated that T cell activation occurs in three phases. The duration of the initial phase of transient, serial DC-T cell interactions is inversely related to Ag dose. It had been assumed that the second phase, characterized by stable DC-T cell contacts, is necessary for T cell activation, however, here we show that this is not always the case. T cells interacting with DCs presenting Ag at low abundance and with a short half-life did not transition from phase one to phase two, whereas a higher dose of the same Ag yielded robust phase two transition. T cells exposed to either antigenic constellation proliferated and developed equivalent effector functions, including cytokine production and cytotoxicity, over the first two days after priming. There are profound differences in the transcriptome at 12h and 24h after activation between CD8 T cells exposed to antigenic constellations that did or did not promote phase two interactions. Only T cells that had undergone stable contacts gave rise to memory, whereas activating conditions that did not support stable contacts yielded immunological amnesia. T cells can make fate decisions in vivo within a few hours after Ag exposure that result in long-term memory or abortive effector responses and correlate with the kinetics of T cell-DCs interactions.
Mechanisms that affect long-distance activity of the 3′ regulatory region of the immunoglobulin heavy chain gene locus (111.31)
Authors: Volpi Sabrina , Chatterjee Sanjukta , Ju Zhongliang , Verma-Gaur Jiyoti , Hassan Rabih , Emelyanov Alexander , Feeney Ann , Birshtein Barbara 
Published: January 2023

Abstract
The 3' regulatory region (3' RR) of the Igh locus works at long distances on VH and I region promoters to initiate germline transcription (GT) and promote class switch recombination (CSR). The 3' RR contains multiple elements, including enhancers (hs3a-hs4), and a proposed insulator region containing CTCF binding sites, i.e. hs5/6/7 and the downstream region (“38kb”). To better understand how the 3' RR functions, we used chromatin immunoprecipitation assays to monitor transcription factor binding sites in splenic B cells that undergo GT and CSR (LPS+/-IL4), or are deficient in GT and CSR (p50-/-), or do not undergo CSR despite efficient GT (anti-IgM+IL4). The hs5-7 and 38kb regions were observed to contain multiple Pax5 binding sites and Pax5 was shown to interact with CTCF. We found that the Pax5 binding profile to the 3' RR dynamically changed during CSR. The role of the hs5-7 region was assessed by genomic deletion. B cells from hs5-7 KO mice showed a modest increase in expression of the nearest downstream genes. In addition, Igh alleles in KO mice were in a less contracted configuration compared to WT Igh alleles and showed a two-fold increase in the usage of proximal VH7183 gene families. Hs5-7 KO mice were essentially indistinguishable from wild type mice in B cell development, allelic regulation, class switch recombination, and somatic hypermutation. These observations suggest redundancy and synergism among the multiple modules of the 3′ RR for Igh regulation.
Immunologic dysfunction underlies pathology in a mouse model of Rett syndrome. (111.52)
Authors: Cronk James , Derecki Noel , Djukic Aleksandra , Kipnis Jonathan 
Published: January 2023

Abstract
Rett syndrome is a devastating autism spectrum disorder, characterized by tremors, breathing dysregulation, impaired locomotion, and mental retardation. Most cases are caused by mutation of the X-linked gene, MECP2, which encodes a methyl-CpG-binding protein. Although MECP2 is expressed in many cell types, pathology has been generally attributed to neuronal dysfunction. However, we recently showed striking arrest of disease in the Mecp2-null mouse model of Rett by manipulation of the immune system. LysmCre-directed wild type MECP2 expression in myeloid cells of Mecp2-null mice and bone-marrow transplantation from wild type into Mecp2-null mice both markedly improved several disease sequelae. When peripheral myeloid cells from Mecp2-null mice were examined, they were significantly impaired in cytokine production (TNF and IL-10) and growth factors (IGF-1) after stimulation, and in phagocytosis. Moreover, peripheral organs from Mecp2-mutant mice showed significantly increased levels of monocytes and granulocytes, as well as a striking skew towards a naïve (CD62LHigh/CD44low) phenotype of T cells. In addition, spleens and livers of Mecp2-mutant mice are significantly smaller than those from wild type. Importantly, these findings correlated with data from human patients, who displayed similar hematologic changes. These data suggest that loss of Mecp2 may lead to immunologic dysfunction, which could underlie pathologies seen in Rett syndrome.
Calpain proteases are required for effective clearance of enterobacteria within the peritoneum of mice to prevent systemic infection (112.5)
Authors: Kumar Vijay , Hall Chris , Greer Peter , Craig Andrew 
Published: January 2023

Abstract
The ubiquitously expressed calpain 1 and 2 isoforms are heterodimers consisting of a catalytic subunit (capn1 or capn2), and a common regulatory capns1-encoded subunit, which is required for protease stability and activity. Although calpains regulate neutrophil and macrophage activation, their roles in immunity remain poorly defined. Here, we use fes-driven Cre recombinase (fes-Cre) to delete capns1 in mice, thus eliminating calpain 1/2 activity in Cre-expressing cells. We detect near complete capns1 deletion in hematopoietic cells, consistent with the tissue-specific expression pattern of fes. Next, we compared the response of control and capns1 targeted mice in the feces-in-peritoneum (FIP) model of sepsis (i.p. injection of enterobacteria). At 2-6 hours post infection, mice were sacrificed and bacterial load, neutrophil recruitment, and cytokine levels in peritoneal lavage fluid (PLF) and peripheral blood were compared between genotypes. We observed comparable levels of neutrophil infiltration and cytokine production in PLF from control and capns1 targeted FIP-treated mice. However, bacterial killing was highly reduced (&gt;10-fold) in capns1 targeted compared to control mice; and this correlated with increased enterobacterial escape to the peripheral blood. These observations suggest that calpains are not required for inflammatory cytokine production or neutrophil recruitment, but they are required for bacterial clearance, and may protection against development of sepsis.
Modulation of DNA vaccine immunity by Fas-FasL signaling (113.15)
Authors: Yan Jiabin , Zapata Juan , Pauza C. David , Salvato Maria 
Published: January 2023

Abstract
The effects of apoptotic death on immunogenicity have been studied intensively, but conclusions about its benefits remain controversial. We hypothesized that inhibiting the Fas-FasL signaling pathway would enhance DNA vaccine potency. We were able to confirm and extend the findings from Norman Letvin’s group (Greenland et al, 2007) that Fas KO mice developed much better cellular immune response (CMI) to SIVmac gag in both quality and quantity. Delivered by electroporation, we co-injected B6 mice intramuscularly with plasmids expressing SIVmac gag and pro- or anti-apoptotic molecules. Our studies showed that the dose and ratio between antigen plasmid and apoptosis modifier were two key factors that influence CMI. More importantly, we found that these apoptosis-modifiers had different influences on the CMI of primary and secondary effectors. Both cFLIP and FADD had little influence on primary responses. However, after one boost, cFLIP enhanced CMI at 1:1 ratio while FADD enhanced CMI at 1:2 ratio, where they both down-regulated the Treg population. Unexpectedly, though shRNA-FasL enhanced primary responses, it inhibited secondary responses by up-regulating the Treg population. At a 1:4 ratio shRNA-Fas inhibited the primary response, but it had no influence on the secondary response. Furthermore, we found that Fas co-delivery impaired both primary and secondary CMI. Our results indicate that many circumstances contributing to Fas-FasL signaling affect DNA vaccine potency.
IL-35 is essential for protection against collagen-induced arthritis (CIA) following intervention with Escherichia coli colonization factor antigen I (CFA/I) fimbriae (116.2)
Authors: Kochetkova Irina , Golden Sarah , Holderness Kathryn , Pascual David 
Published: January 2023

Abstract
Mucosal intervention with CFA/I fimbriae effectively diminishes CIA by stimulation of TGF-β+ and IL-10+ regulatory CD39+CD4+ T cells (Tregs), resulting in suppression of Th1 and Th17 cells and IL-27. CFA/I also stimulates Tregs expressing p35 and EBI3 subunits simultaneously, suggesting an essential role of IL-35 in CFA/I-mediated protection. We hypothesize CFA/I fimbriae stimulate endogenous IL-35 production to facilitate protection against autoimmune disease. In testing the relevance of endogenous IL-35 for protection, oral delivery of recombinant CFA/I into EBI3-/- mice on day 14 after CIA induction was found ineffective against CIA compared to similarly treated WT mice, as evidenced by the lack of suppression of IL-17 and IFN-γ (the latter increased 5-fold ). CFA/I-treated EBI3-/- mice lacked enhanced CREB phosphorylation that, in turn, failed to stimulate the transcription of CD39 (apyrase). In fact, surface apyrase activity by EBI3-/- CD4+ T cells was uninduced. Because of the lack of induced CD39 expression, IL-10 production was greatly diminished. Clinical improvement of CIA in CFA/I-treated EBI3-/- mice required further intervention with recombinant IL-35, resulting in the induction of CD39+CD4+ T cells, enhanced TGF-β production, and reduction in IFN-γ and IL-17. Thus, in the absence of endogenous IL-35, mucosal CFA/I fimbriae intervention is ineffective against autoimmune arthritis. Supported by AT-004986.
Neutrophil-derived IL-1β is required for abscess formation in immunity against Staphylococcus aureus (118.2)
Authors: Cho John , Guo Yi , Hebroni Frank , Ramos Romela , Plasier Seema , Matsushima Hironori , Takashima Akira , Iwakura Yoichiro , Cheung Ambrose , Cheng Genhong , Lee Delphine , Simon Scott , Miller Lloyd 
Published: January 2023

Abstract
Neutrophils have historically been viewed as phagocytes involved in direct killing of pathogens. Here, the mechanism of neutrophil recruitment and abscess formation during an infection was investigated by using a mouse model of Staphylococcus aureus cutaneous infection. Global gene expression analysis of S. aureus-infected skin of wild-type and IL-1R-deficient mice demonstrated that IL-1R activation was crucial for the upregulation of genes involved in neutrophil recruitment. IL-1β triggered IL-1R activation in this model and using IL-1β-reporter mice line, we surprisingly found that neutrophils were the predominant IL-1β-producing cells at the site of infection. S. aureus-induced IL-1β production by mouse and human neutrophils was mediated by the pattern recognition receptors, TLR2 and NOD2, and the ASC/NLRP3 inflammasome. Importantly, IL-1β-expressing neutrophils were essential for abscess formation and bacterial clearance since adoptive transfer of wild-type, but not IL-1β-deficient neutrophils, rescued the immune defects in IL-1β-deficient mice. Taken together, this study defines a new mechanism for abscess formation in which neutrophil-derived IL-1β, induced by TLR2, NOD2 and inflammasome activation, is required for effective neutrophil recruitment and host defense during a S. aureus skin infection.
Effects of anti-CD52 antibody treatment on immune cell depletion and progression of disease in murine systemic lupus erythematosus (119.13)
Authors: Boutin Paula , Severy Peter , Roberts Bruce , Kaplan Johanne , Rao Sambasiva 
Published: January 2023

Abstract
CD52 is expressed at high levels on lymphocytes and to a lesser extent on innate immune cells in humans and mice. Given this expression pattern, we investigated the effect of an anti-mouse CD52 antibody on immune cell depletion and potential therapeutic benefit in lupus prone NZB/NZW-F1 mice. 27 week old mice received either one or two courses of 25mg/kg anti CD52 antibody, three times a week for 2 weeks. Control mice received PBS or a control mouse IgG2a antibody. Anti-CD52 treatment resulted in a significant depletion of nearly 90% of blood lymphocytes. Repopulation kinetics in blood showed that B and T lymphocytes returned to baseline levels within two months post anti-CD52 treatment. Anti-nuclear antibodies decreased transiently but significantly one month post treatment. Proteinuria levels were significantly decreased in the anti CD52 treated group and remained low compared to the control group until 49 weeks of age suggesting a marked improvement in kidney function. Anti-CD52 treatment also provided a significant survival benefit with more than 80%of mice in the treated group surviving at 49 weeks of age compared to only 10% in the control group. These data provide evidence for a beneficial effect of anti-CD52 treatment on disease progression in NZB/NZW-F1 mice and suggest a potential application to human SLE.
Short-term helminth infection inhibits type 1 diabetes independently of the Th2-type response (119.5)
Authors: Mishra Pankaj , Patel Nirav , Wu Wenhui , Bleich David , Gause William 
Published: January 2023

Abstract
Helminth infection can control a number of autoimmune inflammatory diseases in experimental models including type 1 diabetes (T1D).The molecular mechanisms of heminth mediated control of T1D are not yet determined,but it is generally thought that the associated immunoregulation is caused by the potent and highly polarized Th2-type response driven by IL-4.In these studies, nonobese diabetic (NOD) IL-4-/- mice were infected with a strictly enteric nematode parasite.Remarkably,we showed that the helminth-induced control of T1D remained intact. Elevations in CD4+ T cell STAT6 phosphorylation were inhibited,while suppression of STAT1 phosphorylation was sustained,as were increases in FOXP3-,CD4+T cell IL-10 production.Furthermore, protection still occurred if parasites were expulsed with an anti-helminth Rx after only two weeks infection.Oral antibiotic treatment did not effect helminth-mediated protection indicating that intestinal microbiota did not play a major role.Blockade of IL-10 signaling in NOD-IL-4-/-,but not NOD mice,during this short interval abrogated protective effects resulting in pancreatic β-cell destruction and T1D development.These studies indicate that helminth infection triggers multiple immune regulatory components that are induced and can act independently.Their combined effects help explain the potency of helminth-mediated control of pathologic inflammation and suggest future strategies for helminth-mediated therapeutic treatment of this autoimmune disease.