bluuebunny/crossref_metadata_2025_split huggingface dataset:
MDSC suppression of B cell responses in murine retrovirus-induced immunodeficiency: a role for VISTA (IRC4P.603)
Authors: Green Kathy , Wang Li , Noelle Randolph , Green William 
Published: January 2023

Abstract
Inhibition by myeloid derived suppressor cells (MDSC) of T cell responses is well established in tumor microenvironments. We demonstrated (Green et al., 2013) induction of monocytic MDSCs during infection of B6 mice by LP-BM5 retrovirus, which causes profound immunodeficiency. These MDSCs suppressed not only T, but also B cell, responsiveness ex vivo. Whereas MDSC inhibition of stimulated T cell proliferation and IFN-gamma production was ~100%, iNOS/NO dependent, MDSC suppression of B-cell responses was only ~50% dependent on iNOS/NO - as shown by using iNOS inhibitors and iNOS k.o. mice as a source of MDSCs. We then discovered an additional mechanism(s) in MDSC inhibition of (only) B cell responsiveness that involved VISTA, a new negative checkpoint regulator. Using anti-VISTA blocking mAb, or LP-BM5 infected VISTA-/- MDSCs, MDSC inhibition of B cell responses was dependent on MDSC-expressed VISTA — again accounting for ~50% of total MDSC suppression. Combining the use of reagents to block both iNOS/NO and VISTA lead to an additive, if not synergistic, abrogation of MDSC suppression of B cell responsiveness. Consistent with a direct role of VISTA, in the absence of MDSCs, a VISTA-Ig fusion protein also partially inhibited B cell responsiveness. These results were compatible with a role for MDSC in LP-BM5-induced immunodeficiency and highlight involvement of multiple and unique suppressive pathways in the under-studied area of MDSC suppression of B cell responses.
Loss of cell surface CD47 ‘clustering’ formation and the binding avidity to SIRPα during epithelial cell apoptosis (IRC4P.453)
Authors: Lu Zhiyuan 
Published: January 2023

Abstract
CD47, a ‘self’ marker expressed in most cell types, interacts with immunoreceptor SIRPα expressed on phagocyte to initiate inhibitory signaling that prevents healthy cells from being cleared by phagocytes. Previous studies have suggested that cell may lose surface CD47 during cell aging or apoptosis. In the present study, we demonstrated that the majority of CD47 molecules localize in lipid rafts forming ‘punctate’ pattern in healthy cells, whereas in apoptotic cells, the level of cell surface CD47 wasn’t decreased, but CD47 moved out of rafts and redistributed evenly on the plasma membranes. Importantly, clustering of CD47 in the lipid rafts of cell plasma membranes provided a high binding avidity to SIRPα, and inhibited macrophage phagocytosis of healthy cells. In contrast, dispersed CD47 on apoptotic cell surface resulted in a significant reduction of binding avidity to SIRPα, leading to failure of the protection of apoptotic cells from phagocytosis by macrophages. Disruption of lipid rafts with methyl-β-cyclodextrin treatment disrupted CD47 clustering on cell surface, leading to decreased binding avidity of cells to SIRPα therefore being engulfed by macrophages. Thus, our study reveals that CD47 normally localized in lipid rafts in non-apoptotic cells but redistributed evenly on the plasma membranes when apoptosis occurred, the transformation of CD47 greatly reduced the strength of CD47- SIRPα engagement, resulting in the phagocytosis of apoptotic cells by phagocytes.
Crossreactive influenza A(IAV)-Specific CD4 memory cells enhance viral load during lymphocytic choriomeningitis (LCMV) infection (IRC5P.635)
Authors: Selin Liisa , Agarwal Priti , Kraft Anke , Wlodarczyk Myriam 
Published: January 2023

Abstract
IAV is a common human respiratory pathogen with a strong association with heterotypic and heterologous immunity. IAV-immune mice challenged with LCMV develop detrimental effects with both increased virus titers and immunopathology. Crossreactive CD8 T cell responses between these two viruses mediate the enhanced lung pathology. Here, we questioned whether crossreactive CD4 memory cells in IAV-immune mice could play a role in increasing viral titers during the subsequent LCMV infection. Preferential depletion of memory CD4 but not CD8 cells in IAV-immune mice prevented the increase in LCMV titers. In IAV+LCMV mice there was an early increase in CD4 cells with a shift in the CD4/CD8 ratio. Luminex cytokine assays suggested that there was an increase in Th2 cytokines, IL-4 and IL-5, in the spleen of IAV+LCMV mice, which was IAV CD4 memory cell dependent, as IL-4 decreased in the CD4 depleted mice. Depleting IL-4 or IL-5 returned LCMV titers to naïve levels while adding rIL-4 and rIL-5 together to naïve mice increased virus titers. This suggests that the crossreactive heterologous response was more Th2-polarized and that since memory cytokines are produced early they may shift the normally strong Th1-type response to LCMV towards a more Th2-type response, inhibiting appropriate CD8 activation and impeding viral clearance. This shift to stronger Th2-type response would contribute to detrimental effects as LCMV requires a strong CD8 response and perforin to clear.
Post-transcriptional regulation of interferon lambda during viral infection (IRM5P.640)
Authors: Schwerk Johannes , Thomas Kerri , Aarreberg Lauren , Jarret Abigail , Hong MeeAe , Savan Ram 
Published: January 2023

Abstract
Interferon lambda (IFN-λ) has gained increasing attention recently as an important mediator of antiviral protection in hepatitis C virus (HCV) infection. Similar to many cytokines, we have shown that expression of IFNL is regulated on a post-transcriptional level. Interestingly, single nucleotide polymorphisms (SNPs) within the IFNL genes dictate the outcome of acute HCV infection and serve as a prognostic marker for therapy of chronic HCV infection. Previously, we demonstrated that a functional SNP (rs4803217) within the 3'-untranslated region (UTR) of IFNL3 affects transcript stability and correlates with HCV clearance (G/G) or persistence (T/T) in infected patients and this is mediated by miRNAs and AU-rich elements. In our current study we have identified RNA-binding protein(s) (RBPs) that differentially regulate IFNL3 variants. We identified RBP candidates by carrying out mass spectrometry analysis on both variants of IFNL3 mRNA. We found that these candidates exclusively interact with the IFNL3 (T/T) mRNA. Intriguingly, gene expression of one candidate RBP is strongly induced upon stimulation of cells with HCV RNA or viral PAMP. Collectively, our data suggest that IFNL3 mRNA is post-transcriptionally regulated by miRNA and RBP-mediated mechanisms and that HCV potentially hijacks these regulatory mechanisms to suppress host antiviral responses.
The role of STING in T lymphocytes (IRM5P.643)
Authors: Poltorak Alexander , Larkin Bridget , Surpris Guy , Ilyuha Vladimir 
Published: January 2023

Abstract
The cytoplasmic protein Stimulator of Interferon Genes (STING) plays an essential role in sensing intracellular pathogens and initiating type I IFN responses in myeloid cells. STING detects the presence of cytoplasmic DNA presented by various DNA-binding proteins (e.g. IFI16, DDX41, DAI, RNA Pol III); it also directly binds cyclic dinucleotides produced by intracellular bacteria or by the DNA-binding cyclic GAMP synthase (c-GAS). Once activated, STING phosphorylates TBK1 and IRF3 to trigger type I IFN production. To date STING has only been studied in macrophages and dendritic cells, but early reports showed expression of STING in a variety of tissues including the thymus and spleen, prompting us to ask whether STING might have a functional role in T cells, which account for the majority of cells in the thymus and a larger proportion of cells in the spleen than macrophages and dendritic cells. Here, we show that STING can be activated in T cells by the small molecule DMXAA, resulting in IFNβ production and increased expression of numerous interferon stimulated genes (ISG)—the first evidence to our knowledge of type I IFN production by T cells. Furthermore, RNA-sequencing data revealed unanticipated differences between unstimulated wild type and STING-/- T cells, with STING -/- T cells exhibiting increased expression of genes associated with cytotoxic T lymphocytes, indicating that STING-mediated signaling in T cells may regulate the development of particular T cell subsets.
Defining the chromatin landscape of the Il2-Il21 locus in CD4+ T cells (IRM6P.653)
Authors: Pham Duy , Winstead Colleen , Hatton Robin , Weaver Casey 
Published: January 2023

Abstract
IL-2 and IL-21 are pleiotropic cytokines that control key aspects of the immune response including proliferation, cell survival, and differentiation of multiple cell lineages. Despite their co-localization in the genome, there are both overlapping and divergent patterns of expression of these cytokines during T cell development and differentiation, suggesting both coordinate and distinct transcriptional control within the Il2-Il21 locus. Employing the assay for transposase-accessible chromatin using sequencing (ATAC-seq), we demonstrated that the Il2 promoter and distal regulatory elements spanning the Il2-Il21 locus are accessible as early as 30 min following TCR activation while chromatin accessibility of the Il21 promoter requires IL-6 stimulation. Further, CTCF recruitment and chromatin looping analyses defined a boundary element between the Il2 and Il21 genes. In addition, we identified several conserved non-coding elements in the Il2-Il21 intergenic region that have both repressor and enhancer activities on the Il2 or Il21 transcriptional activity. This study provides insight into the chromatin landscape of the Il2-Il21 locus and identifies regulatory elements responsible for the coordinate and differential expression of IL-2 and IL-21.
Regulation of the immunological synapse and T cell function by the c-terminal eps-15 homology domain-containing protein-dependent endocytic recycling. (IRM7P.711)
Authors: Iseka Fany , Goetz Benjamin , Cypher Luke , Bielecki Timothy , Storck Matthew , Band Vimla , Band Hamid 
Published: January 2023

Abstract
The immunological synapse (IS) is a specialized membrane domain with localized display of T-cell receptor (TCR) in contact with a similar display of peptide-loaded MHC on antigen presenting cells (APCs). Aberrant IS function is linked to ineffective tumor killing and autoimmunity. Accumulating evidence indicates a key role of endocytic traffic in the generation and maintenance of the IS. The C-terminal Eps-15 Homology Domain-containing proteins (EHD1-4) are essential regulators of endocytic recycling of surface receptors. Yet, nothing is known about their role in immune cell function. EHD-regulated receptors include the MHC-I and MHC-II proteins, and EHDs regulate vesicle budding at neural synapse. Our hypothesis is that EHD-dependent recycling of TCR and accessory receptors on T cells and MHC-II on APCs is required for the formation and stability of the IS. Indeed, using antigen-specific TCR transgenic CD4+ T-cells, we observe an accumulation of EHD proteins at the interface of T cells and APCs. CD4+ T-cells from floxed EHD1,3,4 mice bearing CD4-Cre and an antigen-specific TCR transgene demonstrate reduced antigen-driven proliferation. Further in vitro and in vivo analyses are being carried out to test the idea that endocytic recycling orchestrated by EHD proteins plays an important functional role in the formation and/or maintenance of IS and in T-cell function.
Reevaluating the biochemical valency of native TCR/CD3 complexes isolated from T cells (IRM7P.708)
Authors: Reed Brendan , Gil Pages Diana , Palmer Ed , Schrum Adam 
Published: January 2023

Abstract
The αβ T cell antigen Receptor (TCR) is a multi-protein complex expressed together with CD3 subunits (γδεζ). The conventional model has it as monovalent with a stochiometry of (αβγδε2ζ2); however, some previously published work reported observation of bivalent complexes with two αβ heterodimers. To reevaluate the valency of the TCR, we have subjected T cell digitonin-solubilized complexes to immunoprecipitation detected by flow cytometry (IP-FCM), size exclusion chromatography, and other methods for detecting complex size and subunit composition. Our results indicate that precisely bivalent TCRs are found among surface-expressed complexes independent of cross-linking by strong antigenic ligands. Their detection can be masked in the presence of Coomassie reagent from Blue-native PAGE conditions, or if antibodies used in detection assays are themselves bivalent. Therefore, bivalent TCR/CD3 complexes can be found under the biochemical conditions that have classically defined the minimally expressed TCR/CD3 unit (digitonin solubilization). Further investigation is required to determine the functional relevance of these bivalent TCR complexes, although greater antigenic binding and signaling is predicted over that of monovalent TCRs.
PLZF expression maps the early stages of ILC1 lineage development (LYM2P.720)
Authors: Constantinides Michael , Gudjonson Herman , McDonald Benjamin , Ishizuka Isabel , Verhoef Philip , Dinner Aaron , Bendelac Albert 
Published: January 2023

Abstract
Among the variety of tissue-resident NK-like populations recently distinguished from classical recirculating cNK cells, liver innate lymphoid cells type I (ILC1) have been shown to represent a distinct lineage that originates from a novel PLZF-expressing ILC precursor (ILCP) strictly committed to the ILC1, ILC2 and ILC3 lineages. Here, using PLZF-reporter mice and cell transfer assays, we studied the developmental progression of ILC1s and demonstrated substantial overlap with stages previously ascribed to the cNK lineage, including pre-pro-NK, pre-NK precursor (pre-NKP), refined NKP (rNKP) and immature NK (iNK). Although they originated from different precursors, the ILC1 and cNK lineages followed a parallel progression at early stages and diverged later at the iNK stage, with a striking predominance of ILC1s over cNKs early in ontogeny. While a limited set of ILC1 genes were dependent on PLZF for expression, characteristically including Il7r, most of these genes were also differentially expressed between ILC1s and cNKs, indicating that PLZF together with other, yet to be defined, factors contribute to the divergence between these lineages.
Homeostatic regulatory T cell trafficking in peripheral lymph nodes (LYM2P.731)
Authors: Tong Alexander , Allen Frederick , Huang Alex 
Published: January 2023

Abstract
Regulatory T cells (Tregs) express the canonical marker Foxp3 and are critical for suppressing the immune response in homeostatic and inflammatory conditions. As widely studied as CD4+Foxp3+ Tregs are in mice, their physiologic trafficking and scanning behavior of antigen-presenting cells in secondary lymphoid organs (SLOs) have yet to be quantitatively analyzed. Our laboratory has previously described the dynamics of naïve T cell trafficking through SLOs and scanning of dendritic cells, revealing that CD4+ T cells and CD8+ T cells have distinct dynamic behaviors in the lymph node (LN). On average, CD4+ T cells spend less time scanning for self-peptide/MHC (self-pMHC), dwell shorter in LNs, and egress faster compared to CD8+ T cells. In this study, we use flow cytometry and 2-photon laser scanning microscopy to quantitate the trafficking kinetics and surveillance strategy of naïve Tregs in C57BL/6 mice LNs and to compare their behavior to conventional T cells. Our data reveal differences in naïve Treg trafficking in mesenteric versus other peripheral LNs. We also show that self-pMHC recognition regulates the scanning behavior and localization of Tregs in peripheral LNs. In addition, we describe a novel imaging platform for high-resolution intravital microscopy of T cell behavior within mesenteric LNs. These results add to mounting evidence that self-pMHC interactions dynamically control physiologic Treg retainment and contact-dependent suppressive function in peripheral LNs.
Regulation of Foxo1 in T cell homeostasis (LYM2P.733)
Authors: Sullivan Jenna , Thomas Kerri , Campbell Daniel 
Published: January 2023

Abstract
The Foxo (forkhead box O) family of transcription factors has been shown to be important for maintaining homeostasis of both effector and regulatory T cells. Interesting Foxo1 is necessary for proper development and function of regulatory T cells (TR) and absence of Foxo1 results in fatal inflammation due to TR dysfunction. During normal conditions phosphorylation of Foxo1 by Akt results in inactivation of the transcription factor and translocation from the nucleus. We have bred mice that contain a floxed non-phosphorylatable Foxo1 allele under control of CD4-cre (CD4cre-Foxo1CA), resulting in constitutive activation of Foxo1 in both CD4 and CD8 T cells. Mice which are unable to properly regulate Foxo1 have reduced body weight, chronic inflammation and develop spontaneous autoimmunity. CD4cre-Foxo1CA displaying symptoms of autoimmunity have tissue damage in the lung along with increases in eosinophils, alveolar macrophages and mucus production. In the periphery CD4cre-Foxo1CA mice have reduced TR, increased activated effector T cells and an altered B cell compartment. Together this data demonstrates that proper regulation of Foxo1 is essential for T cell homeostasis and prevention of autoimmunity.
Constitutively active ezrin desensitizes IL-7 signaling and impairs T cell homeostasis (LYM2P.735)
Authors: Park Jung-Hyun , Luckey Megan , Liu Yin , Shaw Stephen 
Published: January 2023

Abstract
IL-7 signaling results in tethering of the IL-7 receptor to the actin cytoskeleton, which is mediated by the linker molecules ezrin and moesin. To understand the role of cytoskeleton linker molecules in cytokine signaling, we analyzed mice expressing a constitutively active ezrin transgene in T cells. The ezrin transgene was generated by introducing a point mutation at a conserved C-terminal Thr residue (567T-&gt;E) that results in a constitutively open conformation of ezrin. Interestingly, in mice expressing the constitutively active ezrin transgene (T567E-Tg), peripheral T cell numbers were significantly reduced and T cell survival was severely impaired. Moreover, T567E-Tg T cells were defect in IL-7 signaling even as they expressed high levels of surface IL-7 receptor proteins. Additionally, ezrin T567E-Tg induced downregulation of CD8 coreceptor expression, suggesting a “coreceptor tuning” effect of activated ezrin on CD8 T cells. Coreceptor tuning is a model of T cell homeostasis which posits that cytokine signals tailor CD8 coreceptor gene expression to the self-specificity of the TCR. In agreement, TCR disengagement restored IL-7 signaling in T567E-Tg CD8 T cells. Thus, constitutively active ezrin desensitizes IL-7 receptor signaling through increased TCR signaling but not through direct interference with the IL-7 receptor. The molecular mechanisms of ezrin activation on TCR signaling and T cell homeostasis will be discussed.
Metabolic damage and premature thymus aging caused by stromal catalase deficiency (LYM2P.722)
Authors: Griffith Ann , Venables Thomas , Shi Jianjun , Farr Andrew , Van Remmen Holly , Szweda Luke , Fallahi Mohammad , Rabinovitch Peter , Petrie Howard 
Published: January 2023

Abstract
T lymphocytes are essential mediators of immunity produced by the thymus in proportion to mass. The thymus atrophies rapidly with age, resulting in diminished new T cell production. Decreased thymic output is compensated by duplication of existing cells, but results in progressive dominance by memory T cells, and decreased ability to respond to new pathogens or vaccines. We find that accelerated thymic atrophy results from stromal deficiency in the reducing enzyme catalase, leading to increased damage by reactive oxygen species (ROS) generated during aerobic metabolism. Genetic complementation of catalase diminished atrophy, as did chemical antioxidants, providing a mechanistic link between antioxidants, metabolism, and normal immune function. Progenitor lymphoblasts represent the primary source of thymic ROS, likely acting on stromal cells in trans. We propose that thymic atrophy represents a conventional aging process that is accelerated by stromal catalase deficiency in the context of an intensely metabolic lymphoid environment.
Affinity for self drives the preferential accumulation of promiscuous CD4+ T cells over the lifespan. (LYM2P.726)
Authors: Deshpande Neha , Way Sing Sing , Kuhns Michael 
Published: January 2023

Abstract
T cells discriminate self from foreign peptides presented in the context of self-major histocompatibility complex (pMHC) molecules via clonotypic T cell receptors (TCRs). CD8+ T cell recognition and responsiveness to foreign pMHC is known to diminish over the lifespan, which is consistent with gradual thymic involution over time. How the affinity of the CD4+ T cell compartment for self-pMHC, and its capacity to bind foreign-pMHC change over the lifespan are basic aspects of T cell biology that remain largely unexplored. Experimentally restricting thymic selection is known to allow degenerate CD4+ T cells to develop. This suggests that they might accumulate in the CD4+ T cell compartment over time. We report that, while old mice (18-22 months) contain fewer CD4+ T cells than adults (8-12 weeks), those that remain have a higher intrinsic affinity for self-pMHC. Old mice also have more cells that bind distinct foreign-pMHCs, either alone or in combination. The numerical increase of these subsets with age directly correlates with their affinity for self-pMHC. However, no relationship was observed between affinity for self-pMHC and responsiveness to foreign-pMHC. These data demonstrate that the CD4+ T cell compartment preferentially accumulates promiscuous constituents with age as a consequence of higher affinity T cell receptor interactions with self-pMHC. These results have important implications for the design of immunotherapeutics targeting CD4+ T cells for long-term efficacy.
Immunoglobulin relative genes were up-regulated in the liver of cystic echinococcosis mouse (MPF2P.757)
Authors: Lv Guodong , Liu Hui , Li Juan , wen Hao , Lin Renyong 
Published: January 2023

Abstract
Cystic echinococcosis is a neglected parasitic disease all around the world, which due to the infection of Echinococcus granulosus larva in the intermediate host, such as human and sheep. The liver is the major battlefield of the host defends against the parasite, and many immune response and metabolism happened here. This article is aimed to study the gene expression of liver participates in this process, by use of C57 as the experimental animal model and microarray technology. The results showed that 77 genes were up-regulated and 17 genes were down-regulated in the liver adjacent to the parasite lesion. The bioinformatics analysis showed that the most up regulated genes were correlated with immune response process, signal transduction pathway and protein degradation, and down regulated genes were related to metabolism and cell cycle. Immunoglobulin related genes were predicted participation in many important pathways (Fc epsilon RI signaling pathway, primary immunodeficiency, allograft rejection). In addition, transform growth factor receptor 2 was found increased expression in the infected C57BL/6 liver tissue by microarray (2.29-fold) and RT-qPCR (21.4-fold). Quantitative RT-PCR analysis of a random selection of 18 genes confirmed the reliability of the microarray data. Our results provide a hint that immunoglobulin relative genes might participate the interplay between the host and parasite.