bluuebunny/crossref_metadata_2025_split huggingface dataset:
FIP200 is essential for RIG-I-mediated innate immune signaling
Authors: Li Shitao , Wang Lingyan , Song Kun , Patil Girish , Hao Wenzhuo , Wu Yakun 
Published: January 2023

Abstract
Retinoic acid-inducible gene I (RIG-I) is a cytosolic sensor for recognition of viral double-stranded RNA (dsRNA) and 5′ triphosphate RNA, which induces a robust production of type I interferon (IFN). Following RNA recognition, the caspase activation and recruitment domain (CARD) of RIG-I is released from the repressor domain and subsequently oligomerized to activate downstream signal cascades. Although these sequential steps for RIG-I activation are well established; however, the regulatory mechanism is not well elucidated. In this study, we found that the FAK family kinase-interacting protein of 200 kDa (FIP200) interacted with the CARD domain of RIG-I. Ectopic expression of FIP200 activated RIG-I. By contrast, knockout of FIP200 impaired RIG-I signaling, but not other innate immune signaling pathways, in fibroblasts and macrophages. In vivo study showed FIP200 knockout mice were more susceptible to VSV, but not HSV-1, infection due to the reduced innate immune responses, including type I IFN. Mechanistic analyses found that FIP200 promoted the release of the CARD by competing with the repressor domain of RIG-I. Furthermore, FIP200 formed dimers via its C-terminal tail, which facilitated RIG-I oligomerization and subsequent activation. Taken together, our study defines FIP200 as a new innate immune signaling molecule and facilities RIG-I activation.
Regulation of germinal center response by proinflammatory chemokine CCL3 and follicular regulatory T cells
Authors: Grigorova Irina , Ke Fang , Benet Zachary 
Published: January 2023

Abstract
Follicular regulatory T cells (Tfrs) have been reported to play multiple roles in the control of B cell responses. Tfr repress foreign antigen-specific B cells and plasma cells at the peak of germinal center (GC) response. At the same time they promote GC B cell cycling in IL10-dependent fashion and support optimal affinity maturation. Ex vivo Tfrs can act directly on both Tfh and GC B cells. However, relative contribution of direct Tfr-mediated control of Tfh cells vs GC B cells in vivo has been unclear. Our previous work suggested that GC B cell-intrinsic production of proinflammatory chemokine CCL3 promoted direct GC B cell contacts with Tfr cells and was important for modest negative regulation of B cells at the peak of GC response. In this follow up study we have addressed the role of CCL3 in the long-term regulation of GCs. We have also assessed, which subset of GC B cells upregulates production of CCL3 and which receptors on Tfr cells may respond to this chemokine. We found that in addition to the role of CCL3 in the modest repression of foreign antigen-specific B cells at the peak of GC response, it was also important for longer-term participation of B cells in GCs. Both the negative and positive regulation of GC B cells by CCL3 was dependent on the presence of Tregs. We also found that only about 10% of GC centrocytes that were Myc-positive upregulated expression of CCL3 and that Tfr chemotaxis to CCL3 chemokine ex vivo was dependent on both CCR5 and CCR1 chemokine receptors. Further studies are underway to determine the role of Tfr cells in the negative and positive CCL3-mediated regulation of GCs.
Role of NK cells in circadian regulation of lung inflammation
Authors: Sengupta Shaon , Naik Amruta , Issah Yasmine , Forrest Kaitlyn 
Published: January 2023

Abstract
Influenza is a leading cause of respiratory mortality and morbidity. While inflammation is necessary for fighting influenza, a fine balance of anti-viral defense and host tolerance is crucial to successful recovery from the same. Circadian rhythms form an anticipatory system wherein various aspects of cellular physiology oscillate across a 24hrs period; these rhythms have been known to modulate various facets of immunity.
We have recently demonstrated that circadian rhythms control lung inflammation and injury in influenza A virus (IAV) infection. A hallmark of circadian regulation is a difference in outcomes based on time of day of infection. Indeed, we found that C57bl6 mice infected with IAV (PR8) at the beginning of their active phase (ZT11) had 3-fold higher mortality than littermates infected at the beginning of the rest phase (ZT23). This difference disappeared when NK cells were depleted (with NK1.1 antibody) prior to the infection, confirming the role of NK cells in mediating the circadian regulation of IAV infection.
Next, we investigated the mechanism underlying the role of NK cells in circadian regulation of lung injury. We determined viral titers in the lungs from days 1, 2, 4 and 6 following IAV infection and found that there was no difference between the NK depleted and control animals. This suggests that NK directed circadian control of lung inflammation is not mediated through control of viral replication or burden. We then quantified lung pathology in NK depleted and control animals and found that histological injury was worse in the NK depleted group.
In summary, these data suggest that NK cells mediate circadian regulation of outcomes in IAV through control of host tolerance rather than through direct influence on IAV burden.
The spatiotemporal dynamics of type I IFN response determine viral infection outcome
Authors: Casella Valentina , Argilaguet Jordi , Domenjo Eva , Pedragosa Mireia , Encabo Hector Huerta , Esteve-Codina Anna , Vidal Enric , Bocharov Gennady , López-Rodríguez Cristina , Meyerhans Andreas 
Published: January 2023

Abstract
Type I interferons (IFN-I) play a critical role in shaping the antiviral immune response early after an infection. However, the dynamics by which different immune cell subsets regulate the IFN-I response during the early stages of acute and chronic infections is not completely understood. Here we used the Lymphocytic Choriomeningitis Virus (LCMV)-infection mouse model system to characterize the dynamics of the IFN-I response in acute and chronic infections. Time-resolved spleen-transcriptomes revealed that during an acute infection, IFN-I showed two peaks of expression at days 2 and 5 post-infection. In contrast, in chronically infected mice a single peak of IFN-I genes appeared at day 1. Further analysis revealed that IFN-I genes in acute infection were co-expressed with genes related to inflammatory macrophages, suggesting an important role of these cells determining infection fate. Indeed, we identified metallophilic macrophages as an important source of Ifnb only during acute infection and demonstrated that the subsequent IFN-I receptor (IFNAR) signaling is necessary to induce pro-inflammatory macrophages. In contrast, during chronic infection, early depletion of marginal zone macrophages results in a lack of IFN-I production and the inflammatory response is not induced. Importantly, blockage of the second peak of IFN-I response by IFNAR blockage during an acute infection also resulted in exhaustion of virus-specific CD8 T cells and prevention of lymphoid tissue fibrosis. Further studies are ongoing to decipher the regulatory mechanisms underlying the characterized events, thus revealing universal concepts related to infection fate decisions that are also relevant for persistent human infections such as HIV or HCV.
In vivo visualization of immune responses during rejection of allogeneic tissue in the anterior eye chamber
Authors: Chang Hsin-Fang , Krause Elmar , Paloma Saskia , Rettig Jens 
Published: January 2023

Abstract
The anterior chamber of the eye (ACE) was recently described as a novel imaging site in diabetes research by observing transplanted pancreatic islet activity in the eye of a living animal. The ACE technology is ideally suited for non-invasive and longitudinal in vivo imaging. We take advantage of the ACE window to observe immune responses, especially allorejection of islet cells by cytotoxic T lymphocytes. We transplant pancreatic islets from DBA/1J mice into C57BL/6 recipient knock-in mouse which endogenously express a fluorescent protein (GzmB-mTFP or Bonzo) in T cells. We follow the onset of the rejection after vascularization on islets, when immune cells start to infiltrate into ACE, until the end of the rejection process where the islets are cleaned up for roughly a month by repetitive two-photon microscopy. We find that T cells show less migration velocity on islets of foreign mice than on autologous tissue, indicating T cell activation and recognition on the islets. Interestingly, the temporal infiltration pattern of T cells during the rejection process is precisely regulated, showing enrichment of CD4+ T cells on the islets before arrival of CD8+ T cells in histological studies. We use the ACE platform as a more comprehensive environment to study immune response and focus on T cell killing. We aim to understand the mechanism and regulation of T cell-mediated killing in vivo and to further investigate the killing in gene-deficient mice (i.e. munc13-4 and perforin) that resemble to severe human immune disease.
GPR68 promotes CD4 T cell survival by increasing sensitivity to CD3 signaling
Authors: McAleer Jeremy P. , Griggs Nosakhere , Foster William , Zha Xiangming , Xu Yan 
Published: January 2023

Abstract
CD4 T cells contribute to host defense against pathogens, but are also implicated in autoimmunity and allergies when directed against innocuous antigens. Since Th17 cells are upregulated in several autoimmune diseases, identifying genes involved in their activation, proliferation or survival may lead to novel therapies for inflammatory diseases. We previously demonstrated that the aryl hydrocarbon receptor increases expression of the proton sensing receptor GPR68 in human CD4 T cells. Since T cell clonal expansion is associated with a metabolic shift towards anaerobic glycolysis resulting in extracellular acidification, we tested the hypothesis that GPR68 is required for optimal T cell proliferation and survival following activation. To delete GPR68 in T cells, GPR68-floxed mice were crossed with a strain expressing Cre-recombinase under the CD4 promoter. Purified CD4 T cells from CD4-Cre+ and Cre-negative littermate controls were activated in vitro with anti-CD3 and Th17-inducing cytokines (IL-1b, IL-6, IL-23, TGF-b) for 1–5 days. In the control (Cre-negative) group, T cell numbers increased over the first 2 days following activation and then stabilized from days 3–5. In the GPR68-deficient group (Cre+), T cell numbers significantly decreased after day 2, demonstrating a role for GPR68 in promoting CD4 T cell survival. Nevertheless, IL-17 production was GPR68-independent, demonstrating that GPR68 did not regulate Th17 differentiation. GPR68 was especially critical for survival when low doses of anti-CD3 were used (&lt;2.5ug/mL), but not at a high dose (10ug/mL). Overall, our data demonstrate that GPR68 increases the sensitivity of CD4 T cells to survival signals induced by CD3 stimulation.
The Regulatory Role of PIRB in CD4+ Th17 Mediated Colitis
Authors: Uddin Jazib , Waggoner Lisa , Vanoni Simone , Hoebe Kasper , Divanovic Senad , Munitz Ariel , Hogan Simon 
Published: January 2023

Abstract

Rationale
CD4+T-cell differentiation into effector or memory populations is intrinsically regulated by the delicate balance between activating and inhibitory signals. Previously we identified a role of the inhibitory receptor, Paired Immunoglobulin-like Receptor (PIR) B in the negative regulation of innate immune responses in colitis. The aim of this study is to define the involvement of PIRB in CD4+ Th17 development and regulation of CD4+ Th17-dependent colitis.

Results
We demonstrate an intrinsic deficiency in PirB−/− Th17 in vitro polarization and cell survival. Specifically, polyclonal activation of PirB−/− Th17 cells lead to increased cell death and enhanced caspase activation (# of Dead cells, WT vs PirB−/−: 17.6 ± 2.3 × 103 vs 38.5 ± 5.8 × 103; # of Caspase 3/7+ cells: 9.8 ± 1.8 × 102 vs 19.7 ± 1.2 × 102; mean ± SEM, p &lt; 0.05). In vivo, PirB−/− Il10−/− mice were protected from development of Il10−/− spontaneous colitis phenotype (Clinical Score, Il10−/− vs PirB−/− Il10−/−: 3.3 ± 0.6 vs 0.14 ± 0.08, p &lt; 0.01; Histological Score: 2.3 ± 0.4 vs 1.2 ± 0.2; mean ± SEM, p &lt; 0.01) and this was associated with reduced CD4+ Th17 cells in the mesenteric lymph nodes (% IL-17a+ cells, Il10−/− vs PirB−/− Il10−/−: 2.5 ± 0.3 vs 1.2 ± 0.1; mean ± SEM, p &lt; 0.001). To test the intrinsic effects to the CD4+ T-cell compartment, we performed the CD4+ CD45RBhi T-cell transfer model of colitis. Rag−/− mice which received PirB−/− naïve CD4+ T-cells were protected from T-cell mediated colitis (% Change in Body Weight: −3.5 ± 4.9 % WT; 20.7 ± 4.6 % PirB−/−; p &lt; 0.001; Histological Score: 3.8 ± 0.2 WT; 1.0 ± 0.4 PirB−/−; mean ± SEM, p &lt; 0.001).

Conclusions
These data support the concept that PIRB regulates CD4+ Th17 differentiation and development of T-cell-dependent colitis phenotype.
Role of PRMT5 in cholesterol metabolism and Th17 pathogenicity
Authors: Sengupta Shouvonik , Webb Lindsay M , Laliotis Georgios , Tsichlis Philip N , Guerau-de-Arellano Mireia 
Published: January 2023

Abstract
Protein Arginine Methyltransferase (PRMT) 5 is an enzyme catalyzing symmetric dimethylation (SDM) of arginine. This post-translational modification is known to be involved in oncogenesis and embryonic development. Our previous work has shown that PRMT5 is induced during T cell activation. However, the role and mechanisms by which PRMT5 modulates T helper (Th) cell polarization and autoimmune disease have not yet been elucidated. To study the impact of PRMT5 on gene expression programs induced in activated T cells, we developed a conditional PRMT5 knockout (KO) mouse model in which PRMT5 deletion can be induced in CD4+ T cells after thymic development and performed RNA sequencing (RNAseq) analyses in 3-day activated naïve CD4 T cells. We found that PRMT5 promoted expression of cholesterol biosynthetic pathway enzymes that produce Retinoid-Related Orphan Receptor (ROR) agonists that activate ROR-gt and promote Th17 differentiation. Indeed, Th17 differentiation was blunted in PRMT5 KO T cells. Finally, we identify the cholesterol biosynthesis pathway regulator SREBP-1 as a target of PRMT5 SDM. This work shows that PRMT5 expression in activated T cells is needed for the cholesterol biosynthesis gene expression program, generating ROR-gt agonistic activity and promoting Th17 differentiation. These results point to T cell PRMT5 and the downstream cholesterol biosynthesis pathway as promising therapeutic targets in Th17 cell-based diseases.
Smad signaling determines the fate of activated CTLs via multiple intersecting signaling pathways
Authors: Chandiran Karthik , Suarez-Ramirez Jenny E , Hu Yinghong , Ugur Zeynep , Kaech Susan M , Cauley Linda S 
Published: January 2023

Abstract
Immune responses to an infection are controlled by various factors including antigens, co-stimulatory molecules and cytokines present in the tissue micro-environment. TGFβ is a pleiotropic cytokine that modulates immune response and cellular differentiation usually through SMAD (Smad 2,3 & 4)-mediated signaling cascade. Interestingly, TGFβ and Smad4 have independent and opposing roles in determining the fate of activated CTLs. While TGFβ-receptor mediated signaling is required for resident memory (TRM) cells, Smad4 is required for effector (TEff) and central memory subsets (TCM). However, the mechanism behind TGFβ as well as Smad4 mediated differentiation is yet to be unraveled. Using transgenic animal models and pharmacological inhibitors, we investigate the role of TGFβ and multiple SMAD proteins in determining the fate of activated CTLs. We identified that while canonical TGFβ signaling, through Smad2 and Smad3, induces CD103 expression (TRM), Smad4 inhibits CD103 expression thus preventing TRM differentiation. In addition, targeted-ablation of Smad4 alters the expression of various transcription factors that participate in fate determination, including Eomes and KLF2. Although Eomes has previously been implicated in negative regulation of CD103, over-expression of Eomes does not affect CD103 expression in the absence of Smad4. This suggests that Smad4 is required for negative regulation of CD103. These results reveal a novel central role for Smad4 in guiding the fate decisions of activated CTLs and tissue localization via multiple intersecting signaling pathways.
Bone marrow T cell sequestration as a novel mode of CNS immune privilege
Authors: Wilkinson Daniel S , Champion Cosette , Chongsathidkiet Pakawat , Wang Haichen , Laskowitz Daniel , Fecci Peter 
Published: January 2023

Abstract
The central nervous system (CNS), although a site of relative immune “privilege,” is continuously monitored by immune cells. The CNS must possess means for limiting excess inflammation that can otherwise cause irreparable damage or death. Recently, we characterized a unique mode of cancer-induced immunosuppression whereby T cells become sequestered in high numbers in the bone marrow (BM) of humans and mice with intracranial tumors. Sequestration of T cells is mediated in part by the loss of sphingosine-1-phosphate receptor 1 (S1P1) from the T cell surface. Interestingly, this phenomenon occurs only when tumors are located intracranially, but not peripherally. This suggests that sequestration is not mediated by brain tumors themselves, but instead represents tumors usurping of a novel mechanism for CNS immune privilege designed to limit T-cell access to the CNS. Consequently, we investigated whether BM T cell sequestration occurs in other CNS disorders, such as stroke. In a murine model of stroke, immune alterations recapitulated those observed in intracranial tumors. These changes include severe but transient lymphopenia, lymphoid organ shrinkage, and BM T cell sequestration. As with intracranial tumors, BM T cell sequestration was mediated by loss of surface S1P1 on T cells. A mechanistic understanding of CNS-driven BM T cell sequestration will enable the development of novel therapeutics to limit neuroinflammation and damage in the context of CNS pathologies.
Functional dissection of the Il2ra superenhancer reveals developmentally regulated and cell type specific elements
Authors: Spolski Rosanne , Li Peng , Oh Jangsuk , Liu Chengyu , Ren Min , Enomoto Yutaka , West Erin , Shin Boyoung , Rothenberg Ellen , Leonard Warren 
Published: January 2023

Abstract
The expression of the IL-2 receptor a chain is tightly regulated during early T cell development and in mature lymphoid populations by either cytokine stimulation or T cell receptor interactions. IL-2Ra expression can be either constitutive, as in some double negative thymocytes and T regulatory cells, or inducible, as in CD4+and CD8+mature T cells. Previously, our lab identified a super-enhancer in the mouse Il2ra locus that extensively bound STAT5 and controlled expression of this gene in mature T cells. To further dissect developmental and cell type specific expression of this super-enhancer, Crispr-Cas9 mediated deletion was used to generate mutant mice lacking either individual or groups of STAT5 binding sites in either the upstream region or the first intron. Deletion of the upstream region led to the absence of CD25 expression in DN2 and DN3 thymocytes as well as a significant reduction of CD25 expression on regulatory T cells, but minimal effect on inducible CD25 expression in mature T cells. Analysis of individual upstream elements in reporter assays revealed a specific element that controlled high activity in DN3 cells and a Treg cell line, with markedly diminished activity in the presence of Notch inhibitors. In contrast, deletion of an intronic region markedly diminished both IL-2 and TCR-induced expression of CD25 in vitro, while having little if any effect on CD25 expression in DN thymocytes or Treg cells. These data reveal that the Il2rasuper-enhancer is composed of multiple elements that preferentially mediate either constitutive or inducible Il2ragene expression. Further analysis of these elements will define mechanisms for regulation and potentially manipulation of CD25 expression in autoimmune and other disease states.
Blimp1 suppresses proliferation in human regulatory T cells as a potential homeostasis regulator
Authors: Ding Ying , Malek Thomas R 
Published: January 2023

Abstract
B lymphocyte-induced maturation protein 1 (Blimp1), encoded by the PRDM1 gene, is a multifunctional transcriptional regulator that has established roles in mouse T cells. However, the mechanisms underlying its function in the proliferation, suppressive function, and homeostasis of human regulatory T cells (Tregs) are not known. To directly evaluate the role of Blimp1 in human Tregs, Blimp1α, the active isoform of Blimp1 that has dominant expression, was knocked out by Crispr-Cas9 using dual-targeting sgRNAs. High knockout efficiency was verified at DNA, RNA, and protein level by T7E1, RT-PCR, and Western blot analyses, respectively. Knockout of Blimp1α in cultured human Tregs resulted in increased cell number, upregulated Ki67 expression, and enhanced [3H]thymidine incorporation, consistent with a normal inhibitory role of Blimp1α in the proliferation of human Tregs. Compared with control cells, Blimp1α-knockout Tregs showed high CD25 expression and enhanced tyrosine phosphorylation of STAT5 (pSTAT5), suggesting a potential role of Blimp1 in regulation of IL-2R signaling. In vitro suppression assay showed that knockout of Blimp1α slightly decreased the suppressive function of Tregs. Knockout of Blimp1α also increased the expressions of Tigit and CD62L, but decreased the expressions of Foxp3, CD73, and Bcl-2, suggesting that Blimp1α may contribute to maintaining Treg identity. Collectively, our results are consistent with a model whereby Blimp1α regulates homeostasis of human Tregs by constraining proliferation in part by limiting IL-2R signaling while promoting Treg function and identity.
A ‘sweet spot’ for complement receptor CD46 activity: direct regulation of glycolytic vs. moonlighting functions of glycolytic enzymes
Authors: Kunz Natalia , Le Friec Gaelle , Singh Parul , Lavender Paul , Kazemian Majid , Hess Christoph , Kemper Claudia 
Published: January 2023

Abstract
Autocrine engagement of the complement receptor CD46, driven by T cell receptor (TCR) activation on human CD4 T cells, is critical for human Th1 induction: Processing of the intracellular CD46 domains by gamma-secretase and their nuclear translocation mediates the expression of nutrient transporters and enables metabolic reprogramming required for cell growth, expansion and effector function. How, at the molecular level, CYT-1 enables this fundamental cellular adaptation remains unknown. Co-immunoprecipitation experiments with antibodies against cleaved CYT-1 revealed an association of CYT-1 with the glycolytic enzyme glyceraldehyde 3-phosphate dehydrogenase (GAPDH). A strong, dose-dependent interaction was confirmed via ELISA and Microscale Thermophoresis- (MST−) based experiments in vitro and via proximity ligation assays (PLAs) in CD4 T cells ex vivo. Unexpectedly, subsequent experiments demonstrated that CYT-1 did not affect metabolic activity of GAPDH but rather fostered its des-oligomerization. CYT-1-driven des-oligomerization of GAPDH ‘unleashed’ its non-canonical ‘moonlighting’ function: CYT-1-generated GAPDH monomers displayed augmented mRNA binding abilities and stabilized metabolic mRNAs in living CD4 T cells. Importantly, this CYT-1capacity is not confined to GAPDH: CYT-1 binds and des-oligomerizes several other glycolytic enzymes. These data identify CD46 as a ‘shape-shifter’ of glycolytic enzyme activity, critically balancing the canonical (glycolysis) versus non-canonical (e.g. posttranscriptional regulation) activity – further substantiating the notion that autocrine complement is a critical regulator of normal cell physiology.