bluuebunny/crossref_metadata_2025_split huggingface dataset:
B cell anergy: Atheroprotective, yet vulnerable to atherosclerotic conditions
Authors: Waseem Tayab , Keeter William Coles , Moriarty Alina , Edemobi Stefan , Pham Michael , Getahun Andrew , Cambier John C , Galkina Elena 
Published: January 2023

Abstract
Anergy is the major mechanism for peripheral tolerance. Recent reports highlight the role of B cell anergy in lupus, type 1 diabetes, and arthritis, but little is known about the induction and maintenance of anergic B cells within atherosclerosis. ARS/A1 mice have B cells that respond with moderate affinity to Ars hapten, but also cross-react with low affinity to endogenous ssDNA resulting in an anergic B cell repertoire. To explore the role of B cell anergy in atherosclerosis, we examine ARS/A1 and BL/6 littermate controls that have been fed a western diet for 16 weeks and injected with AAV-PCSK9 to induce atherosclerosis. Our data showed that ARS/A1 mice had 44% less lesions, and a decreased inflammatory profile compared to BL/6 controls. The role of B cells in atherosclerosis varies by B cell subsets. Whereas marginal zone B cells (MZ) are atheroprotective, follicular B cells (FO) accelerate atherosclerosis. To further explore how an atherosclerotic environment affects B cell subsets, we compared the percentages of splenic B cell subtypes in PCSK9-treated vs healthy ARS/A1 controls. Our data showed a significant decrease in ARS/A1 FO B cells and an increase in ARS/A1 MZ B cells suggesting a skewing of B cell subsets upon exposure to atherosclerotic conditions in ARS/A1 mice. Surprisingly, we detected an increased calcium response upon BCR crosslinking and increase levels of CD86 in B cells from PCSKS-9-injected ARS/A1 vs BL/6 controls. Overall, our data suggests that while anergy is atheroprotective, the inflammatory environment seen within atherosclerosis may prime B cells to increase the responsiveness of anergic B cells to activation.
Discovery of perforin-expressing killer B cells in vertebrates
Authors: Sunyer J. Oriol , Shibasaki Yasuhiro , Takizawa Fumio , Gonzalez Michael , Boudinot Pierre 
Published: January 2023

Abstract
Our previous work has shown the existence of distinct subsets of B cells in vertebrates that are highly phagocytic. To understand further the involvement of B cells in other potential innate immune functions, we performed the first comparative transcriptome analysis on FACS-sorted IgT+ and IgM+ B cells in rainbow trout, a primitive teleost fish species. To our surprise the gene that showed the highest differential expression between these two B cell subsets was perforin, a molecule that is not typically associated with B cells. The results obtained by transcriptome were expanded by further RT-PCR analysis confirming that unlike IgM+ B cells, IgT+ B cells expressed high transcript levels of several perforin isoforms, including, prf1-like-B, prf1-like-C and prf1-like-D. We also confirmed the unique expression of these perforin genes in IgT+ B cell by single cell transcriptome analysis. Moreover, we produced antibodies against these perforin molecules and demonstrated by immunohistochemistry the presence of several of these perforin isoforms in IgT+ B cells. Since perforin is a cytolytic protein we hypothesized that IgT+ B cells could possess cytotoxic activity similar to that of other perforin-expressing cells. To confirm this hypothesis, we tested the potential cytotoxic capacity of IgT+ B cells towards several mammalian cell lines, such as HL-60. Our results show that the killing activity of IgT+ B cells was significantly greater than that of IgM+ B cells. As IgT+ B cells and the IgT antibodies they produce play key roles in fish mucosal surfaces, our results strongly suggest a cytotoxic role for mucosal B cells in these species. Overall, our findings demonstrate a previously unrecognized new function for vertebrate B cells in immunity.
How TLR9 Signaling shapes the survival, differentiation and the metabolism of B cells
Authors: Akkaya Munir , Akkaya Billur , Theall Brandon , Traba Javier , Pena Mirna , Pierce Susan K 
Published: January 2023

Abstract
The signaling cascades initiated by binding of the antigen to B cell receptor (BCR) leads to rapid increases in cellular respiration, nutrient uptake and expression of various activation markers. However, unless a second, independent stimulus is received soon after antigen binding, BCR signaling does not lead to B cell proliferation and differentiation. Instead, BCR signaling alone leads to a dysregulation of cellular calcium homeostasis which in turn causes mitochondrial dysfunction and a phenomenon called activation induced cell death. The second signal can be provided by Toll like receptor (TLR) signaling, indicating the presence of an acute infection or through B cell-T cell interactions that rules out that the initial antigen was a prohibited self-antigen. Additionally, there is an interplay between TLR versus T cell mediated second signals, namely that TLR signaling trumped the need for the antigen-stimulated B cell to interact with T cells to receive a ‘go’ signal. TLR stimulation decreased B cells’ ability to capture, process and present antigens to solicit help from T cells. Rather TLRs directly boosted B cell antibody and cytokine secretion and proliferation. Thus, TLR signals drive B cells toward rapid T cell-independent differentiation to plasma cells providing rapid neutralizing antibody production to fight off infections quickly. In contrast B cells that receive their survival signals from T cells are induced to undergo a time-consuming process that is necessary for antibody affinity maturation and long-lasting immune memory. Therefore, the TLR driven shortcut to quick antibody comes with a price which is the absence of “crème de la crème” antibodies that would protect the body from subsequent infections for years to come.
Interleukin-27-producing B cells are critical regulators of immunity during persistent viral infection
Authors: Pratumchai Isaraphorn , Huang Zhe , Zak Jaroslav , Teijaro John R 
Published: January 2023

Abstract
B cells regulate immune responses by both generating antibodies and through cell surface interactions and cytokine production that provide signals to various cells to modulate humoral and cell-mediated immunity. During persistent viral infection, IL-27R is required for viral control which correlates with impaired anti-viral CD4+ T cell responses and lower LCMV-specific antibody production. Here, using mice with conditional B cell–specific IL-27 p28 deletion, we identify IL-27-producing B cells as key players in promoting control of persistent viral infection. Mice in which B cells lacked IL-27 p28 expression lost the ability to control persistent LCMV infection. The impaired immunity was associated with the reduction of GC B cells, plasma cells and Tfh cells. In addition, these mice also displayed reduced virus-specific CD8 T cells and lost the ability to expand CXCR5+ follicular CD8 T cells following anti-IFNAR1 treatment, suggesting that B-cell-derived IL-27 p28 regulates immunity by providing signals to T cells. To assess the role of IL-27 signaling in T cells we generated IL-27R conditional KO mice by mating IL-27Ra-floxed mice with CD4 and Granzyme B-Cre strains. Mice in which IL-27Ra was conditionally ablated in all T cells lost the ability to control persistent LCMV infection. In addition, these mice produced significantly lower titers of virus-specific IgG2a throughout the course of infection despite similar levels of virus-specific IgG1. Finally, we identify plasma cells expressing the transcription factor Blimp1 as a major source of IL-27 p28 during persistent LCMV infection. Overall, our study highlights the importance of IL-27-producing B cells in regulating T cell responses and control of persistent viral infection.
Distinct Antibody Repertoire of Cerebral Spinal Fluid B Cells from Healthy Controls
Authors: Husain-Krautter Sehba , Vos Duncan , Gallego Juan A , Malhotra Anil K , Rothstein Thomas L 
Published: January 2023

Abstract
Antibodies have been implicated in the pathogenesis of several neuropsychiatric diseases. Although these disease-associated antibodies typically circulate (eg, Sydenham’s Chorea), they can arise from autoreactive B cells in situ, located within the central nervous system itself (eg, Multiple Sclerosis). Although normal human cerebral spinal fluid (CSF) has been classically considered to be acellular, the presence of B cells in CSF from healthy controls has been reported (Ho et al. 2013, Kleine 2015). In order to provide context in elucidating the pathophysiology of autoreactive B cells in disease, we questioned the origin of CSF B cells in healthy donors. Specifically, we asked whether CSF B cells represent a distinct population (select subset), or a random assortment, of peripheral B cells in the same individual. We obtained paired samples of CSF and peripheral blood (PB) from 4 healthy control volunteers. B cells were isolated by immunofluorescent staining and cell sorting, followed by immunoglobulin amplification and sequencing. We confirmed that each normal CSF sample contained small numbers of B cells. We found highly significant differences in V-D-J usage of immunoglobulin from these B cells as compared to V-D-J usage of matched PB B cells, with significance determined by Chi-square goodness of fit, confirmed by resampling-based permutation tests. These results indicate that B cells are selected for entry into, or persistence in, the central nervous system, and are not simply a random reflection of B cells circulating at any given time. This suggests the value of examining the repertoire of CSF B cells that may be pathogenic agents in neuropsychiatric diseases whose origin remains obscure, such as schizophrenia.
The role of innate immune cells in Contact Hypersensitivity
Authors: On Kathy , Tikoo Shweta , Jain Rohit , Weninger Wolfgang 
Published: January 2023

Abstract

Background
Contact hypersensitivity (CHS) is a murine model used to investigate the role of the immune system in eliciting the skin’s inflammatory response to small compounds called haptens. Although many studies have identified the immune cell subsets involved in mediating the inflammatory response, the spatiotemporal behaviour of these immune cells in vivo is not well-defined.

Aim
The aim of this project is to delineate the spatiotemporal behaviour of numerous innate immune cell subsets during the different phases of CHS. In particular, we will be focusing on the behaviour of dermal dendritic cells (dDCs), perivascular macrophages (PVM) and mast cells.

Methods
Utilising the technique of intravital multiphoton microscopy, we have observed changes in the behaviour of the above-mentioned immune cell subsets following sensitisation with the hapten 2,4-dinitro-1-fluorobenzene (DNFB).

Results
Intravital imaging of homeostatic ear skin identified three migratory behaviours exhibited by dDCs as they interact with sessile PVM. Immediately post-sensitisation, a significant increase in the formation of stable cellular interactions were observed between dDCs and PVM. However, following mast cell degranulation, granule uptake by PVM resulted in the dissociation of these stable interactions. Hence, implying the potential egress of dDCs to the draining lymph nodes for T cell priming.

Conclusion
Our findings have identified a novel cellular mechanism involved in mediating the sensitisation phase of CHS. Further investigation into the molecular mechanisms regulating these cellular events will potentiate the identification of possible therapeutic targets.
T-bet deficiency impairs CD4 T cell effector trafficking to Influenza A Virus infected lungs but not their anti-viral functions
Authors: Dhume Kunal , Finn Caroline , McKinstry Karl Kai 
Published: January 2023

Abstract
CD4 T cell responses against Influenza A Virus (IAV) are predominantly classified as TH1, characterized by strong IFN-γ production. However, the protective role of IFN-γ is unclear, suggesting that full TH1 polarization may be dispensable for effective CD4 immunity. We test this hypothesis by analyzing transgenic CD4 T cells recognizing IAV that are deficient in the transcription factor T-bet (Tbx21−/−), the ‘master regulator’ of TH1 differentiation. 3×106 Wild-type (WT) or Tbx21−/− effector cells, primed under TH1 conditions, were transferred to naïve congenic WT mice then infected with lethal IAV. Tbx21−/− effectors protected mice, promoting similar reductions in viral titer and weight loss recovery as WT cells. However, T-bet deficiency impacted production of several cytokines by the effectors resulting in less IFN-γ and GM-CSF but more IL-2, IL-4 and IL-17. Although the peak magnitude of WT and Tbx21−/− effector responses were similar in secondary lymphoid organs, significantly fewer Tbx21−/− cells were observed in the lungs. We thus titrated effectors to 1×106 cells, to expose any potential differences in protection arising from differential lung homing. Lower effector transfer resulted in higher viral titer and delayed weight loss recovery in mice given Tbx21−/− versus WT cells. Mechanistically, Tbx21−/− cells expressed lower levels of the chemokine receptor CXCR3. CXCR3 blockade in mice given WT effectors reduced their numbers in the lungs and delayed weight loss recovery matching patterns seen in mice given Tbx21−/− effectors. Thus, while prototypical TH1 functions are dispensable for protection against IAV, T-bet-dependent chemokine responses are required to maximize anti-viral CD4 responses at the site of infection.
Inositol polyphosphates promote T cell-independent humoral immunity via the regulation of Bruton’s tyrosine kinase
Authors: Seong Rho H , Kim Wooseob , Min Hyungyu 
Published: January 2023

Abstract
T cell-independent (TI) B cell response is critical for the early protection against pathogen invasion. The regulation and activation of Bruton’s tyrosine kinase (Btk) is known as a pivotal step of B cell antigen receptor (BCR) signaling in TI humoral immunity, as observed in patients with X-linked agammaglobulinemia (XLA) experiencing a high incidence of encapsulated bacterial infections. However, key questions remain as to whether well-established canonical BCR signaling pathway is sufficient to regulate the activity of Btk. Here, we find that inositol hexakisphosphosphate (InsP6) acts as a physiological regulator of Btk in BCR signaling. Absence of higher order inositol phosphates (InsPs), inositol polyphosphates, leads to an inability to mount immune response against TI antigens. Interestingly, the significance of InsP6-mediated Btk regulation is more prominent in IgM+ plasma cells. Hence, present study identifies higher order InsPs as principal components of B cell activation upon TI antigen stimulation and presents a novel mechanism for InsP-mediated regulation of the BCR signaling.
Integrative analysis of human memory B cell coding and non-coding transcriptomes
Authors: Moroney Justin B , Vasudev Anusha , Taylor Julia R , Zan Hong , Pertsemlidis Alexander , Casali Paolo 
Published: January 2023

Abstract
An effective response against previously experienced pathogens is contingent upon the unique functionality of memory B cells. These display intrinsic differences over naïve B cells, including longer lifespan and rapid response to antigen with production of high-affinity, class-switched antibodies. We have developed an integrated analysis of mRNA, miRNA and long non-coding RNA (lncRNA) profiles to determine how the mRNA transcriptome intersects with epigenetic regulatory non-coding RNAs to shape the functionality and phenotype of human memory B cells (CD27+IgG+ and CD27+IgA+) as compared to their naïve B cell counterparts (CD27−IgD+IgM+). Differential expression analysis revealed a novel gene signature shared by CD27+IgG+ and CD27+IgA+ cells, distinguishing memory from naïve B cells. Additionally, CD27+IgD+ B cells, which are not considered bona-fide memory, revealed a transcriptional identity straddling naïve and switched memory B cells. Signaling pathway analysis implicated the “memory” gene signature in the generation, homing and survival of class-switched memory B cells. Integrated analysis of mRNA and miRNA transcriptomes showed that in memory B cells the expression of select genes was dependent upon miRNA-mediated regulation. lncRNA analysis revealed that some of these RNAs clustered with IgH genes, thereby suggesting a role of such lncRNAs in the regulation of the IgH locus. Additional data suggested that select lncRNAs act as miRNA sponges. Thus, we have identified a novel set of genes that play a role in the generation and maintenance of memory B cells and have provided evidence that these genes are subjected to integrated regulation by distinct sets of miRNAs and lncRNAs.
IL-21 is a major suppressor of IgE production in mice and humans
Authors: Allen Christopher DC , Yang Zhiyong , Wu Chung-An M , Targ Sasha 
Published: January 2023

Abstract
Antibodies of the IgE isotype may elicit potent allergic reactions and their production is tightly controlled. The tendency to develop allergic responses has been historically thought to depend on the balance between T helper type 1 (Th1) responses that suppress IgE, versus T helper type 2 (Th2) responses that promote IgE production, based on the activities of the prototypical cytokines interferon gamma (IFN-γ) and interleukin (IL)-4, respectively. Here we reevaluated this paradigm by a direct cellular analysis, demonstrating that IgE production was not limited to type 2 immune responses, yet was generally constrained in vivo. We determined that the cytokine IL-21 was a critical negative regulator of IgE responses, whereas IFN-γ was dispensable. IL-21 inhibited IgE responses by directly engaging the IL-21 receptor on B cells and triggering STAT3-dependent signaling. We reconcile previous discordant results between mouse and human B cells and reveal that the inhibition of IgE responses by IL-21 is modulated by CD40 signaling. The suppression of IgE responses by IL-21 correlated with reduced IgE germline transcription, but was independent of apoptosis, indicating that IL-21 inhibits IgE class switch recombination. These findings establish key features of the extrinsic regulation of IgE production by cytokines.
APRIL signaling in human antibody secreting cells promotes cellular response via p38 and differential immediate early gene regulation
Authors: Stephenson Sophie J , Care Matthew A , Doody Gina M , Tooze Reuben M 
Published: January 2023

Abstract
Long-lived antibody secreting cells (ASCs) persist as quiescent plasma cells (PCs) in niche microenvironments. However, we know little about how ASCs integrate these signals to drive changes in function. APRIL is an important in vivo niche factor, for which the primary receptor is BCMA, but to our knowledge APRIL-induced signaling and consequent gene regulation in primary human ASCs are poorly defined. In particular, little is known of signals that APRIL generates at the transition from proliferative plasmablast to quiescent plasma cell, an important transition in ASC differentiation.
Using a model system of in vitro PC differentiation, which utilizes APRIL signaling as a key survival promoting factor, we demonstrate that significant levels of multimerized mega-APRIL are needed to deliver signals into ASCs. This in part reflects a process of cell intrinsic shedding of BCMA, the APRIL receptor, as previously reported by others. Blockade of proteolytic shedding by gamma secretase inhibitors enhances surface BCMA expression and mega-APRIL induced PC survival, generating phenotypically mature PCs with prolonged longevity from in vitro and ex vivo plasmablasts. At the plasmablast to plasma cell transition APRIL induces a selective pattern of MAP kinase activation in human ASCs, preferentially activating p38. This contrasts to another niche signal, SDF1, which preferentially targets ERK. Differential gene regulatory responses are evident for immediate early genes, with APRIL producing a preferential activation of FOSB relative to FOS or EGR1. The results provide the basis for systematically exploring the signaling and gene regulatory networks involved in the response of human ASCs to niche factors supporting PC survival.
Sumoylation of RORgt regulates TH17 differentiation and thymocyte development
Authors: Sun Zuoming , He Zhiheng , Zhang Jing , Huang Zhaofeng , Du Qian , Li Ning , Zhang Qiang , Chen Yuan 
Published: January 2023

Abstract
RORgt controls the differentiation of TH17 cells involved in autoimmunity such as experimental autoimmune encephalomyelitis (EAE). RORgt also regulates thymocyte development and lymph node genesis. Here we show sumoylation as a novel mechanism to regulate RORgt function. Loss of Sumo3, but not Sumo1, dampens TH17 differentiation and delays the progression of thymic immature CD8+cells (ISP). RORgt is SUMO3-modified at lysine 31 (K31), and mutation of K31 to arginine (RORgtK31R) in mice to prevent sumoylation impairs RORgt-dependent function including defective TH17 differentiation, resistance to TH17-mediated EAE, accumulation of thymic ISP and lack of Peyer’s patches. Mechanically, RORgt-K31 sumoylation stabilizes the binding of SRC1 through recruiting histone acetyltransferase KAT2A. Lastly, E3 ligase PIAS4 binds and sumoylates RORgt at K31, and regulates RORgt-dependent TH17 differentiation and progression of thymic ISP. This study thus demonstrates sumoylation as a critical mechanism for regulating RORgt function, and reveal new drug targets for preventing TH17-mediated autoimmunity.
Batf promotes and stabilizes Th17 cell development by antagonizing the actions of STAT5
Authors: Pham Duy , Silberger Daniel J , Hatton Robin D , Weaver Casey Todd 
Published: January 2023

Abstract
T helper type 17 (Th17) cells secrete IL-17A, IL-17F, IL-21, and IL-22 cytokines and can provide protection against extracellular pathogens or promote certain immune-mediated diseases. The basic leucine zipper transcription factor ATF-like (Batf) contributes to the transcriptional programming of multiple effector T cells but is indispensable for Th17 cell development. Here, we have interrogated mechanisms by which Batf may act to stabilize the Th17 cell phenotype. We find that in vitro differentiated Th17 cells have increased expression of Th1 and Treg signature genes in the absence of Batf. In addition, Batf-deficient (Batf KO) mice succumb to Citrobacter rodentium infection, which correlates with diminished IL-17A and IL-22 cytokine production and increased Foxp3 and Ifng expression compared to WT mice. We find that Batf acts to maintain the Th17 program in long-term Th17 culture conditions by repressing Th1 and Treg programming, at least in part, by antagonizing STAT5 binding to Th1- and Treg-specific genes. Our findings suggest that a function of Batf in Th17 development and maintenance is the antagonism of the actions of STAT5.