bluuebunny/crossref_metadata_2025_split huggingface dataset:
B cell Rad52 deficiency enhances immunoglobulin class switching through increased recruitment of Ku70/Ku86 to S region double-strand DNA breaks (IRM10P.618)
Authors: Tat Connie , Shen Tian , Taylor Julia , Guzman Meghan , Zan Hong , Casali Paolo 
Published: January 2023

Abstract
Class switch DNA recombination (CSR) diversifies the biological effector functions of antibodies and is critical for the maturation of the immune response. It is initiated by AID-mediated generation of DSBs in the switch (S) regions that will undergo recombination, mainly through Ku70/Ku86-mediated nonhomologous end-joining. It has been shown, however, that Ku-deficient B cells can undergo CSR, suggesting that other DNA repair mechanisms are at work. Herein, we show that deficiency of Rad52, an important component of the homologous recombination DNA repair pathway, resulted in significantly increased CSR and is associated with increased recruitment of Ku70/Ku86 to the S region DSB ends. In Rad52-/- B cells, the increased role of Ku70/Ku86 in S region DNA recombination was further emphasized by decreased occurrence of microhomologies in S-S junctions and inter-chromosomal c-Myc/IgH translocations. Conversely, enforced expression of Rad52 in B cells impaired CSR and decreased Ku70/Ku86 recruitment to S region DNA, as revealed by ChIP assays. Accordingly, EMSAs using Sμ probes with blunt-ends or short overhangs, revealed that in CSR, Ku70/Ku86 and Rad52 bind to different types of DSB ends. Our findings show that Rad52 modulates CSR by binding to S region DSB ends. This may facilitate a Ku-independent repair pathway, which would resolve AID-mediated S region DSBs, thereby explaining the residual CSR that has been shown to occur in a conditional Ku70/Ku86 B cell knockout.
B cell Rab7 mediates induction of AID expression and class-switching in T-dependent and T-independent antibody responses (IRM10P.605)
Authors: Lou Zheng , Pone Egest , Lam Tonika , Wang Rui , Chen Yuhui , Liu Dongfang , Edinger Aimee , Xu Zhenming , Casali Paolo 
Published: January 2023

Abstract
IgH class switch DNA recombination (CSR) is central to the maturation of the antibody response, as it diversifies antibody biologic effector functions. By constructing conditional KO Igh+/Cγ1-creRab7fl/fl mice, we have previously identified a B cell-intrinsic role for Rab7, a small GTPase that regulates endosome maturation, in CSR and antibody responses. In Igh+/Cγ1-creRab7fl/fl B cells, Rab7 gene is ablated within 48 h of stimulation by IL-4 plus CD154 or LPS, resulting in reduced CSR to IgG1 and IgE. Here, we have addressed the mechanisms underlying the role of Rab7 in CSR. Once Rab7 was ablated, B cells were also defective in CSR to IgA, indicating that Rab7 regulates the central CSR machinery in an Ig isotype-independent manner. Indeed, expression of AID, as essential to CSR, was reduced in Rab7 KO B cells and enforced AID expression rescued CSR. Finally, super-resolution imaging of CD154-stimulated B cells revealed that Rab7 formed foci, within which CD40 was enriched. These findings, together with our demonstration that Rab7 mediated canonical NF-κB activation, as critical to AID induction, outline a novel role of Rab7 in specific signaling pathways that lead to AID expression and CSR, likely by promoting assembly of signaling complexes along intracellular membranes.
Type I IFNs are master regulators of susceptibility to post-influenza MRSA pneumonia (IRM11P.632)
Authors: Rynda-Apple Agnieszka , Shepardson Kelly , Larson Kyle , Morton Rachelle 
Published: January 2023

Abstract
Bacterial superinfections are common and often life-threatening complications of influenza infection. Others reported that increased susceptibility to superinfection occurs 7 days after influenza infection, and we demonstrated that it was due to decreased IL-13 and concomitant increase in IL13Ra2, which allowed for increased IFN-g, while early IL-13 production at day 3 provided protection from MRSA superinfection. However, mechanisms regulating IL-13 and IFN-g during influenza disease are unknown. We hypothesized that type I IFNs, induced by many respiratory infections, including those with influenza and MRSA are master regulators of susceptibility to superinfection. We determined that similar to the increase in IL-13, levels of IFN-b peaked at days 2-3 after influenza infection and were replaced by IFN-a by day 7, when mice are known to be susceptible to superinfection. At day 3 after influenza infection Ifnar-/- mice were more susceptible to MRSA superinfection, did not produce IL-13, but had increased IL13Ra2 and IFN-g compared to wild-type mice, and administration of rIL-13 to the Ifnar-/- mice partially restored protection from MRSA superinfection. Using bone marrow chimeric mice and Itgax-Cre mice we determined that early protection to superinfection required type I IFN signaling from the CD11c+ cell. These results support a role for type I IFNs in the early protective response to post-influenza superinfection and a role for their regulation of IL-13 and IFN-g.
Molecular regulation of autoimmunity by O-GlcNAcylation of NF-kappaB c-Rel in T lymphocytes (IRM11P.633)
Authors: Ramakrishnan Parameswaran , Tomalka Jeffrey , Jesus Tristan 
Published: January 2023

Abstract
The NF-kappaB protein c-Rel plays a critical role in controlling autoimmunity through regulating T cell function and T regulatory cell development. Type 1 diabetes is an autoimmune disease associated with hyperglycemia and chronic inflammatory complications. We found that hyperglycemia induces O-GlcNAcylation of c-Rel at serine residue 350 and activates the transcription of c-Rel-dependent pro-autoimmune cytokines interleukin-2 (IL-2), interferon gamma (IFNG) and granulocyte macrophage colony-stimulating factor (GM-CSF). Our recent results show that c-Rel O-GlcNAcylation decreases FOXP3 expression in T cells. These results suggest that the glucose metabolism-dependent c-Rel O-GlcNAcylation serves as a key regulatory switch with dual roles in controlling T cell and T regulatory cell function in autoimmune diabetes. Despite decades of research, drugs based on molecular targets to treat type 1 diabetes have remained elusive. This study reveals a novel molecular mechanism that regulates NF-kappaB c-Rel and autoimmune diabetes, with potential to develop novel therapeutics targeting c-Rel O-GlcNAcylation. Moreover, this study serves as the basis to explore the role of c-Rel O-GlcNAcylation in other autoimmune diseases such as celiac disease, lupus and arthritis, where c-Rel function have been implicated.
Posttranscriptional control of allergic airway inflammation by HuR (IRM11P.638)
Authors: Atasoy Ulus , Techasintana Patsharaporn , Gubin Matthew , Magee Joseph , Whitney marlyn 
Published: January 2023

Abstract
RNA binding protein HuR regulates Th2 differentiation by controlling mRNA stability of IL-4, IL-13 and GATA-3. We hypothesized HuR is required for initiation of allergic airway inflammation. We generated a distal lck-Cre ROSA HuRfl/fl mouse model to conditionally ablate HuR prior to T cell activation. HuR KO mice had 50% knockdown efficiency of YFP+ CD4+ T cells. We used ova challenge model of airway inflammation to ascertain effects of HuR KO in T cells. YFP+ HuR KO T cells migrated normally to lungs during ova challenge and had significant reductions in BAL IL-13, cellular inflammation and serum IgE. Additionally, they had completely abolished lung cellular inflammation to levels similar to non-immunized mice. We conducted in vitro activation experiments to determine mechanisms of suppression of airway inflammation. HuR KO CD4+ T cells were sorted into YFP+ (HuR lo) and YFP- (HuR WT) pools and activated. YFP+ T cells had profound decreases in IL-4, IL-5, IL-13 but not IFNλ at mRNA and protein levels. Gata-3 and IL-4 transcription were significantly reduced, as was expression of IL-2Ra (CD25). YFP+ KO T cells have reductions in p-stat5 signaling which is required for robust Th2 differentiation by activation of the IL-4 gene locus. Remarkably, though only 50% of CD4+ T cells have ablated HuR, this was sufficient to completely suppress Th2 differentiation in airway inflammation. These data reveal a pivotal role for HuR in controlling Th2 cytokines and airway inflammation.
Mitochondrial damage-associated molecular patterns exacerbate acute lung injury following burn (IRM11P.640)
Authors: Dunn Julia , Kartchner Laurel , Maile Robert , Cairns Bruce 
Published: January 2023

Abstract
Acute lung injury (ALI) is an inflammatory condition that can occur following infection or trauma and is accompanied by a 40-50% risk of mortality. Burn patients suffer from ALI even without smoke inhalation, rendering them susceptible to life-threatening pneumonia. While models exist to simulate ALI following sepsis, a model is needed to study the mechanisms that drive ALI after trauma. We hypothesize that damage associated molecular patterns (DAMPs) enter circulation following trauma and induce ALI, characterized by cellular infiltration into the lung accompanied by systemic inflammation. Because our 20% total body surface area burn model induces systemic inflammation but not ALI, we administered fragmented mitochondria (MTD) i.v. following the burn. Compared with unburned, vehicle-treated control mice, cellular recovery from lung washes doubled 3h post burn+MTD (mean 2.5± SD 0.5E5 vs. 5.0±0.7E5, *p&lt;0.005), and remained elevated at 24h (6.2±1.7E5*) and 48h (8.2±3.5E5, p&lt;0.05). While serum IL-6 was undetectable in control mice, it was elevated at 3h (348±49 pg/mL*) and 24h (168±47*) following burn+MTD. Our data indicates that i.v. administration of MTD in conjunction with burn injury leads to cellular infiltration into the lung characteristic of ALI that is prolonged up to 48h. Burn with MTD treatment also affected systemic inflammation, evidenced by serum IL-6. Using this model we can investigate immunotherapeutic strategies to attenuate ALI in trauma patients.
Type I interferon regulates GITRL on infiltrating monocyte-derived inflammatory APC to establish early viral control during chronic LCMV infection
Authors: Chang Yu-Han , Zhou Angela , Abdul-Sater Ali , Watts Tania H 
Published: January 2023

Abstract
Disease outcome in chronic viral infections correlates with early viral set-point established by the initial T cell response. Previous studies showed that GITR, an NFκB-activating TNFR family member, sustains CD4 T cell accumulation and help for CD8 T cells at the onset of chronic LCMV infection. While the endogenous effect of GITR on CD8 T cells is largely attributed to enhanced early CD4 T cell help, CD8 T cells are directly responsive to exogenous GITR agonist. How endogenous GITR co-stimulation selectively impacts CD4 T cells early post-LCMV infection (p.i.), however, remains elusive. We hypothesize that CD4 and CD8 T cells interact with distinct antigen presenting cells (APC) and that the availability of GITRL underscores the regulation of GITR co-stimulation. Herein, we identify inflammatory monocyte-derived DC and macrophages (infMΦ) as the dominant GITRL-expressing APC with approximately 5 times higher levels compared to classical DC during LCMV infection. A preliminary experiment showed that deleting exon 2 of GITRL using MΦ-specific Lys-M-Cre recapitulates the marked reduction in Th1 response against LCMV observed in the whole-body GITR knockout. GITRL exhibits similar expression kinetics to type I interferon (IFN-I) with an early but transient peak at 24–48 hours p.i. IFN-I is a potent inducer of GITRL on thioglycollate-elicited peritoneal macrophages (TG-MΦ) ex vivo. Moreover, blockade of IFN-I receptor abrogates up-regulation of GITRL during LCMV infection of TG-MΦ in vitro, as well as on infMΦ in vivo. Together, the current study suggests a critical role for infMΦ in GITR-dependent immunity to LCMV and identifies IFN-I as a key regulator of GITRL on infMΦ in vivo.
PI3K/mTOR-dependent IL-22 production modulates polyfunctional T cell responses in viral hepatitis.
Authors: Yi Panpan , Liang Yuejin , Yuan Denley , Jie Zuliang , Kwota Zakari , Cong Yingzi , Sun Jiaren 
Published: January 2023

Abstract
IL-22 is an important cytokine in modulating the consequences of inflammation in lesions, including the liver. However, the role of IL-22 in Lymphocytic Choriomeningitis Virus (LCMV)-induced viral hepatitis remains obscure. Here, we report that LCMV-induced IL-23 release promoted IL-22 production. And gdT cells and double negative T cells (DNT, CD3+ CD4− CD8− γδTCR− NK1.1−) were the main sources of IL-22 and IL-17 productions following LCMV infection in the liver. Interestingly, we also found that IL-23-stimulated IL-17 production in γδ T cells, and DNT cells were totally dependent on RORγt and PI3K/mTOR, but independent in AhR activities. Although IL-22 production in these two lymphocyte subsets depended on PI3K/mTOR, unlike IL-17 production, IL-22 production required additional signals from RORγt and AhR. Furthermore, IL-22 appeared to act as an important mediator in T cell responses in LCMV-induced viral hepatitis, despite the fact that the IL-22 receptor is restricted to being expressed on non-hematopoitic cells. IL-22−/− mice increased the recruitment of activated T cells to the liver and enhanced polyfunctional cytokine productions in effector CD4+ and CD8+ T cells in LCMV-induced acute or persistent viral hepatitis. Thus, our data revealed a novel connection between IL-23-PI3K/mTOR signaling pathway and the regulation of IL-22/IL-17 productions in the liver, and showed a novel role of IL-22 in modulating the plurifunctionality of anti-viral T cell responses during acute and persistent LCMV infection.
IL-17A negatively regulates lymphatic vessel formation
Authors: Park Hyeung Ju , Kim Min-Gyo , Lee Seung-Hyo 
Published: January 2023

Abstract
Lymphatic vessels (LVs), well-known conduits of immune cells, enable antigen presenting cells (APCs) to enter draining lymph node resulting in the induction of adaptive immune responses against various antigens. During inflammation, LVs are increased and enlarged by the effect of pro-lymphangiogenic factors including vascular endothelial growth factor -A, C, and D secreted by APCs and stromal cells, and facilitate the migration of activated immune cells. However, after antigen clearance, these expanded LVs should be shrunk similar to apoptotic cell death of activated immune cells to maintain homeostasis. It is known that, failure of inflammation resolution causes chronic inflammation in many diseases. Chronic inflammation often accompanies increased LVs which enable continuous antigen delivery and immune cell trafficking from infection sites to draining lymph node. Previously, it was discovered that several cytokines secreted by type 1 and 2 helper T (Th) cells inhibit lymphangiogenesis during resolution phase but less is known about the effect of Th17 cytokines. Here, we show that interleukin-17A (IL-17A) secreted from Th17 cells is a putative negative regulator of lymphangiogenesis in Th17-mediated immune responses, especially during resolution phase. IL-17A suppressed gene expression of lymphatic specific markers in lymphatic endothelial cells. Also, we utilized cholera toxin mixed with chicken egg ovalbumin peptide (CTO) challenge model which induces Th17 dominant inflammation to examine the in vivo effect of IL-17A. Blockade of IL-17A increased LVs and enhanced their function. Thus, this study will provide expanded knowledge on unidentified role of IL-17A as a negative regulator of lymphangiogenesis.
DOCK8 regulates fitness and function of regulatory T cells through modulation of IL-2 signaling
Authors: Singh Akhilesh K , Hagin David , Komal Khushbu , Eken Ahmet , Bhise Gauri , Hubbard Nicholas , Torgerson Troy R , Oukka Mohamed 
Published: January 2023

Abstract
Foxp3+ regulatory T cells (Treg) possess potent immunosuppressive activity critical for the maintaining immune homeostasis and self-tolerance. Defect in Treg cells development or function result in inadvertent immune activation and autoimmunity. Despite of recent advances in Treg cells biology, we still do not completely understand the molecular and cellular mechanisms governing the development and suppressive function of these cells. Here, we have demonstrated an essential role of the Dedicator of cytokinesis 8 (DOCK8), guanine nucleotide exchange factor required for cytoskeleton rearrangement, cell migration and immune cell survival, in controlling Treg cells fitness and their suppressive function. Treg cells-specific DOCK8-deletion led to the spontaneous multi-organ inflammation in mice due to uncontrolled T cells activation and production of pro-inflammatory cytokines. DOCK8-deficient Treg cells are defective in fitness and suppressive function. Furthermore, DOCK8 control IL-2 signaling, crucial for maintenance and competitive fitness of Treg cells, via STAT5 dependent manner. DOCK8 deficient patients are predisposed to autoimmunity and develop colitis, autoimmune hemolytic aremia and vasculitis. Thus, our study provides insight into essential function of DOCK8 in Treg cells and immune regulation, and explains the autoimmune phenotype of DOCK8 deficient patients.
IL-21 regulates the innate immune response to Staphylococcus aureus pulmonary infection.
Authors: Spolski Rosanne , West Erin E. , Li Peng , Kazemian Majid , Leonard Warren 
Published: January 2023

Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) infection is a major complication of viral respiratory infections and immunodeficient states. Although the innate immune response mediated by neutrophils plays a major role in the clearance of MRSA, the cytokine regulation of this process is poorly understood. Here, we investigated the role of IL-21 in the host response to pulmonary MRSA infection. In experiments using a mouse model, Il21r-deficient mice more efficiently cleared pulmonary MRSA infection, suggesting a negative role for IL-21 in MRSA clearance. Interestingly, Il21r KO mice displayed an enhanced “interferon signature” response after pulmonary MRSA infection as compared to WT mice, and blocking the type I IFN response eliminated the ability of Il21r KO mice to more efficiently clear the infection. Despite the more efficient clearing of pulmonary MRSA in Il21r KO than in wild-type mice, when IL-21 was administered to wild-type mice, there was enhanced clearance of MRSA, and this clearance was accompanied by the induction of cytolytic proteases and other components of pulmonary defense. Correspondingly, human peripheral blood neutrophils responded directly to IL-21 with the induction of cytolytic proteases including granzymes, and they displayed enhanced IL-21-induced killing of MRSA that was granzyme-dependent. These data demonstrate that although the chronic absence of IL-21 signaling in Il21r KO leads to the dominant action of type I IFN responses that result in MRSA clearance, IL-21 directly induces a cytolytic program in both human and mouse neutrophils that results in MRSA killing. These data suggest that manipulation of IL-21 signaling may be a strategy for controlling bacterial infections.
IL-4 alters mast cell activation by FcγR
Authors: Haque Tamara , Ryan John J 
Published: January 2023

Abstract
Mast cells are involved in many inflammatory diseases, partly by their production of cytokines that promote inflammation. IgG signaling through FcγRIII/IIb in mast cells is linked to autoimmune disease such as rheumatoid arthritis, but factors controlling this signaling remain unclear. Our group has previously shown that IL-4 augments IgG- mediated TNF production by murine mast cells, but other cytokine secretion was not examined. This may be critical, since we recently found that TNF is not always co-regulated with other cytokines during mast cell activation. In fact, our current data show that IL-4 suppresses IgG-mediated MCP-1 production. Current work is examining a broader range of cytokines and chemokines. These studies suggest that mast cell responses are altered by cytokines in their microenvironment, with distinct and even opposite effects on specific cytokines and chemokines.
The gut-liver axis plays a crucial role in murine immune tolerance in the liver
Authors: NAKAMOTO NOBUHIRO , Ebinuma Hirotoshi , Amiya Takeru , Aoki Ryo , Hayashi Atsushi , Taniki Nobuhito , Chu Po-Sung , Yamaguchi Akihiro , Saito Hidetsugu , Kanai Takanori 
Published: January 2023

Abstract
Hepatic APCs express TLRs that recognize PAMPs or DAMPs and are involved in immune activation and tolerance. We recently showed repetitive Concanavalin A (Con A) injection, a mitogen that preferentially activates T cells, induced immune tolerance in the liver. Here, we investigated the underlying mechanisms of immune tolerance by the gut-liver axis.

METHODS
Male C57BL/6 mice were administered an initial and subsequent sub-lethal dose of ConA to induce immunological tolerance. Liver mononuclear cells were separated 12 h after the final ConA injection and analyzed by flow cytometry. Immune cell subset cytokine production stimulated with TLR ligands was measured. The composition of intestinal bacterial flora was evaluated by comprehensive metagenomics and intestinal permeability was measured by FITC-dextran.

RESULTS
A single ConA injection induced severe liver inflammation, while ConA administration 7 days after initial injection (tolerant phase) increased immunosuppresive CD11c+ DCs (D7-cDC) in the liver and promoted immune tolerance. D7-cDC had regulatory characteristics and produced IL-10 and TGF-β upon TLR9 ligand stimulation. The composition of intestinal bacterial flora along with intestinal permeability changed following ConA injection, and a species of Lactobacillus dramatically increased at tolerant phase. Finally, transplantation of a specific species of Lactobacillus to gut sterilized mice induced immunosuppressive CD11c+ cDCs and reduced liver injury by ConA.

CONCLUSIONS
Dysbiosis with altered intestinal permeability promotes the migration of immunosuppressive cells in the inflamed liver. This study identifies a novel homeostasis pathway that regulates immune tolerance through gut-liver axis.
The cellular composition of the human immune system is shaped by age and cohabitation
Authors: Liston Adrian 
Published: January 2023

Abstract
Detailed population-level description of the human immune system has recently become achievable. We used a “systems-level” approach to establish a resource of cellular immune profiles of 670 healthy individuals. We report a high level of inter-individual variation, with low longitudinal variation, at the level of cellular subset composition of the immune system. Despite the profound effects of antigen exposure on individual antigen-specific clones, the cellular subset structure proved highly elastic, with transient vaccination-induced changes being followed by a return to the unique baseline of the individual. Strikingly, the largest influence on immunological variation identified was cohabitation, with a 50% reduction in immunological variation between individuals who share an environment (parents) compared to the wider population. These results identify local environmental conditions are a key shaper of the human immune system.
AMPKα1 regulates T follicular helper cell metabolism and homeostasis
Authors: Li Xudong , Liang Yuqiong , Shaw Reuben J , Zheng Ye 
Published: January 2023

Abstract
T follicular helper (TFH) cells provide key help to germinal center (GC) B cells during humoral immune response. How TFH cells are metabolically adapted to this unique task is not clear. Here we report that TFH cells have increased AMPK activation and T-cell-specific deletion of Prkaa1, which encodes AMPKα1, results in impaired TFH response at a late time point when TFH cells move into GCs and interact with GC B cells. AMPK activation requires SAP and CD84, which are essential for T-B-interaction, and CAMKK2, which is activated by calcium signaling. AMPKα1 helps sustain TFH response by promoting autophagy, which is upregulated in TFH cells in an AMPK-dependent manner and is required for optimal TFH response. Our results suggest that AMPK plays a critical role in promoting homeostasis of TFH cells by linking TFH-B-interaction and calcium signaling to TFH-cell metabolic programing.