bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regulatory T cells and IL10 suppress pulmonary host defense during early-life exposure to combustion generated radical containing ultrafine particulate matter.
Authors: Jaligama Sridhar , Yadav Nikki , Minso Jagila , Saravia Jordy , Lee Greg , Cormier Stephania 
Published: January 2023

Abstract
Exposure to elevated levels of particulate matter (PM) is associated with adverse respiratory health and increased risk of morbidity and mortality due to respiratory tract viral infections in infants. Our previous studies demonstrated combustion derived PM (CDPM) induced immunosuppression allowing for enhanced influenza disease severity and mortality in neonatal mice. Current studies are aimed at understanding the underlying mechanisms. Neonatal mice (3 day old) were acutely exposed to Air or DCB230 (CDPM), and infected with influenza virus (Flu), Air/Flu and DCB/Flu respectively. Pulmonary T cell profile and immunosuppressive cytokines were analyzed. At 10 days-post exposure, a significant increase in pulmonary Tregs and IL10 coinciding with decrease in protective T helper 1 (Th1) and cytotoxic T cell (Tc1) responses was observed in DCB/Flu mice compared to Air/Flu mice. Further, depletion of Tregs (using anti-CD25 antibody) in DCB mice prior to flu infection increased both Th1 and Tc1 cells, whereas adoptive transfer of DCB-induced Tregs into Air mice and later infection with flu suppressed these responses. To elucidate the role of IL10 in DCB/Flu mice, Air exposed neonatal mice were treated with recombinant IL10 (rIL10) and subsequently infected with flu (rIL10/Flu). rIL10/Air/Flu mice had increased morbidity and pulmonary viral load compared to Air/Flu mice, whereas, IL10 deficient DCB/Flu mice exhibited reduction in pulmonary viral load and morbidity compared to wild-type mice indicative of enhanced protection against flu. Together, these studies demonstrate that PM- induced Tregs and their effector cytokine, IL10, suppress adaptive T cell responses leading to increased influenza severity in infected neonatal mice.
Alveolar macrophages regulate granulomatous inflammation in a mouse model of chronic beryllium disease.
Authors: McKee Amy , Mack Douglas , Fontenot Andrew 
Published: January 2023

Abstract
Chronic beryllium disease is a granulomatous lung disease orchestrated by beryllium-specific CD4+ Th1 cells. In addition to its role as a pathogenic antigen, beryllium has potent effects on innate immune cells. In mice, beryllium exposure causes cellular death and release of alarmins, including IL-1α and DNA. This is associated with accelerated migration of pulmonary dendritic cells from the lung to the draining lymph nodes, upregulation of costimulatory molecules on their surfaces and enhanced priming of effector Th1 cells. These effects are MyD88-dependent but independent of the inflammasome. Our previous characterization of a mouse model of berylliosis showed that in contrast to WT mice, HLA-DP2 transgenic mice exposed to beryllium develop beryllium-specific Th1 responses and peribronchovascular infiltrates in the lung. We wanted to investigate the role of alveolar macrophages in this model using depletion with clodronate liposomes. Intratracheal instillation of mice with clodronate liposomes depleted alveolar macrophages but dendritic cell migration to the draining lymph nodes remained intact. HLA-DP2 transgenic mice depleted of alveolar macrophages generated beryllium-specific Th1 responses in both lung and spleen that were similar to those in mice treated with control PBS-containing liposomes. Surprisingly, however, the depletion of alveolar macrophages severely exacerbated the development of granulomas in the lung. These results implicate alveolar macrophages in regulating granulomatous inflammation in the lung.
Sirt1 modulates AID expression, class switch DNA recombination and somatic hypermutation by repressing NF-kB activity
Authors: shen Tian , Sanchez Helia Nasrollahi , Zan Hong , Casali Paolo 
Published: January 2023

Abstract
As we have suggested, epigenetic factors, such as histone deacetylases (HDACs), play critical roles in modulating the maturation of the antibody response. This entails class switch DNA recombination (CSR) and somatic hypermutation (SHM). CSR and SHM require AID and diversify the specificity and effector functions of antibodies. By showing that HDAC inhibitors (HDIs) that selectively block Classes I/II HDACs (the “classical” Zn-dependent HDACs together with Class IV HDAC), impaired AID and Blimp1 expression, CSR, SHM and plasma cell differentiation, we have previously outlined an important role of these Zn-dependent HADCs in the modulation of antibody response. We found that Sirt1, one of the NAD+-dependent Class III HDACs or sirtuins (Sirts), played an important role in the regulation of CSR and SHM. Sirt1 deacetylated p65, an element of the canonical NF-kB pathway, which mediates AID induction, thereby repressing NF-kB activity. Sirt1 deficiency in B cells led to NF-kB hyperacetylation and activation, which resulted in enhanced AID expression and increased CSR to IgG, IgA and IgE. Conversely, Sirt1 deletion in AID expressing B cells of AicdacreSirt1fl/fl mice, whose B cells contain the normal complement of Aicda genes together with a Cre gene under control of an extra Aicda promoter, resulted in upregulated AID expression, increased CSR and SHM, and enhanced T-dependent and T-independent antibody response. These findings outline an important B cell-intrinsic role of Sirt1 in the modulation of the antibody response. Such a role is independent from and may be in addition to the histone deacetylation activity of this Class III HDAC.
Supported by the NIH grants AI 105813, AI 079705 and ALR TIL grant ALR 295955.
Ezrin regulates inflammation by limiting B cell interleukin-10 production
Authors: Gupta Neetu , Pore Debasis , Matsui Ken , Parameswaran Neetha 
Published: January 2023

Abstract
In addition to their essential role in antibody production, B cells regulate immune responses by secreting effector cytokines. Interleukin 10 (IL-10) produced by B cells is important for controlling inflammation and autoimmunity, underscoring the importance of identifying mechanisms regulating B cell IL-10 production. We have previously demonstrated that the membrane-cytoskeleton linker protein ezrin regulates B cell antigen receptor organization and signaling. Further, we have shown that ezrin undergoes rapid dephosphorylation in naïve B cells treated with LPS, suggesting that it may regulate TLR4-mediated IL-10 production. In the present study, we demonstrate that conditional deletion of ezrin in B cells increases IL-10 production induced by TLR4, but not TLR2 or TLR9, ligation. The MyD88-independent TRIF-TBK1-IRF3 pathway is required for ezrin-deficient B cells to produce higher IL-10 upon LPS stimulation. Treatment of B cells with a novel small molecule inhibitor of ezrin induces its dephosphorylation, and increases LPS-induced NF-κB and IRF3 activation and IL-10 secretion, indicating a role for Thr567 phosphorylation of ezrin in limiting IL-10. Loss of ezrin in B cells results in dampened pro-inflammatory response to a sub-lethal dose of LPS in vivo, which is dependent on increased IL-10 production. Taken together, our data yield new insights into molecular and membrane-cytoskeletal regulation of B cell IL-10 production, and reveal ezrin as a potential therapeutic target in inflammatory diseases.
Hotspots for hormone response elements in Sα switch regions of immunoglobulin heavy chain loci; how estrogen may influence class switch recombination (CSR) and IgA/IgG isotype expression by activated B cells
Authors: Hurwitz Julia L , Jones Bart G. , Sealy Robert E , Xu Beisi , Fan Yiping , Partridge Janet F. , Maul Robert W. , Gearhart Patricia J , Penkert Rhiannon 
Published: January 2023

Abstract
B cell immune responses differ between genders. To investigate mechanisms responsible for these differences, we activated murine B cells with mitogens in vitro in the presence or absence of hormones. We found that additions of estradiol and thyroid hormones to mitogen-activated B cell cultures altered IgA/IgG expression patterns. Chromatin immunoprecipitation (ChIP) analyses then showed that estrogen receptor (ER) associated with the anti-apoptotic bcl-2 gene in LPS-stimulated murine B cells, but the interaction was inhibited by estrogen, possibly explaining variant isotype expression patterns. In search of additional mechanisms, we queried mouse and human immunoglobulin heavy chain switch (S) regions for potential hormone response elements (HRE). In both human and mouse loci, the DNA sequences of Sμ and Sα encompassed an extraordinary number of HRE. For example, there were more than 70 potential estrogen response elements (ERE, G/AG/AT/CT/CG/AnnnTGAC/GC) in Sα regions of both human and mouse loci, yet not a single ERE in Sγ2. Results suggest that hormones impact antibody isotype expression by both indirect and direct mechanisms; they might alter B cell growth, but might also up- and down-regulate class switch recombination (CSR) by direct receptor interactions with Sμ and Sα.
CD277 reduces B cell Activation by HIV Env Immunogens
Authors: Coleman Michelle , Corey Daniel , Ring Aaron R , Corey Lawrence , Weissman Irving L , Stamatatos Leonidas 
Published: January 2023

Abstract
CD277 is a human B7-like molecule. involved in activation of Vγ9Vδ2 T cells. Its counter-receptor is unknown and its role in B cell activation has not been described. B cell lines were stably transduced with the IgG isotype of the inferred germline B cell receptor (BCR) form of the broad and potent HIV-1 neutralizing antibody, VRC01, and stimulated with recombinant HIV Env in Ca2+-dependent activation assays. CD277 ectodomain proteins partially inhibited Ca2+ flux in response to heptameric and trimeric HIV Env. Similar observations were made with B cells expressing an anti-HA BCR, when stimulated with recombinant HA. We conclude that the reduction in B cell activation recorded in the presence of CD277 was not specific for the HIV Env. In contrast, CD277 completely abolished B cell activation that was induced by cross-linking the same BCRs with anti-Fab antibodies. To identify molecules that may serve as counter-receptors for CD277 binding, a fluorescently coupled CD277 ectodomain was utilized to conduct a FACs-based negative selection screen from a pooled lentiCRISPR-Cas9 knockout library (GeCKO). This strategy resulted in a significant reduction in library diversity with the overall sgRNA pool by the end of the screen restricted to a few, highly abundant sgRNAs. Specific binding assays among putative counter-receptors are ongoing. Once identified, CD277 counter-receptors could be targeted for inhibition in vaccination studies, to enhance B cell responses to antigen such as HIV Env. These data indicate an important physiological role for CD277 in inhibiting B cell activation and its role in influencing the B cell repertoire should be pursued.
Single molecular force sensitivity and threshold for the activation of B cell receptors
Authors: Liu Wanli , Wan Zhengpeng 
Published: January 2023

Abstract
B lymphocytes show remarkable mechanosensing capability by utilizing the surface expressed B cell receptors (BCRs) to sense antigens. However, the sensitivity and threshold for the activation of BCRs resulting from the stimulation by mechanical forces are unknown. Here we systemically addressed this question using a ds-DNA based tension gauge tether (TGT) system serving as a predefined single molecular force gauge ranging from 12 to 56 pN to restrict BCR and antigen tension. Utilizing total internal reflection fluorescence microscopy, we observed that IgM-BCR activation is sensitive to single molecular forces. We observed an obvious multi-threshold effect with a low-end 12–16 pN force which triggered a weak activation, whereas a 23–43 pN force initiated a medium-level activation, and a high-end 50–56 pN force produced a strong activation. Such patterned dependence on mechanical forces with multi-threshold effects did not strictly rely on myosin IIA, dynein and integrin. However, the break-through of the high-end but not the medium-level and low-end mechanical force threshold in IgM-BCR activation required myosin IIA and the inside-out activation of integrin. Surprisingly, we found that the activation of the isotype-switched IgG-BCR or IgE-BCR only requires an extremely low threshold of less than 12 pN, providing an explanation for their rapid activation in response to antigen stimulation. Mechanistically, we found that the cytoplasmic tail of the IgG-BCR heavy chain is both required and sufficient to account for the low mechanical force threshold to activate the IgG-BCR. These results defined the single molecular force sensitivity and threshold that are required to activate different isotyped BCRs.
mTOR Complex Signaling through the SEMA4A–Plexin B2 Axis Is Required for Optimal Activation and Differentiation of CD8+ T Cells
Authors: Ito Daisuke , Kumanogoh Atsushi 
Published: January 2023

Abstract
Mammalian target of rapamycin (mTOR) plays crucial roles in activation and differentiation of diverse types of immune cells. Although several lines of evidence have demonstrated the importance of mTOR-mediated signals in CD4+ T cell responses, the involvement of mTOR in CD8+ T cell responses is not fully understood. In this study, we show that a class IV semaphorin, SEMA4A, regulates CD8+ T cell activation and differentiation through activation of mTOR complex (mTORC) 1. SEMA4A−/− CD8+ T cells exhibited impairments in production of IFN-γ and TNF-α and induction of the effector molecules granzyme B, perforin, and FAS-L. Upon infection with OVA-expressing Listeria monocytogenes, pathogen-specific effector CD8+ T cell responses were significantly impaired in SEMA4A−/− mice. Furthermore, SEMA4A−/− CD8+ T cells exhibited reduced mTORC1 activity and elevated mTORC2 activity, suggesting that SEMA4A is required for optimal activation of mTORC1 in CD8+ T cells. IFN-γ production and mTORC1 activity in SEMA4A−/− CD8+ T cells were restored by administration of recombinant Sema4A protein. In addition, we show that plexin B2 is a functional receptor of SEMA4A in CD8+ T cells. Collectively, these results not only demonstrate the role of SEMA4A in CD8+ T cells, but also reveal a novel link between a semaphorin and mTOR signaling.
αv integrins engage autophagy components to regulate B cell immune response
Authors: Acharya Mridu , Sokolovksa Anna , Tam Jenny M , Vyas Jatin M , Stuart Lynda , Lacy-Hulbert Adam 
Published: January 2023

Abstract
Signaling through Toll-like receptors (TLR) such as TLR7 and TLR9 has been implicated in B cell activation by self-antigens and development of autoimmunity. Our recent work based on murine models has identified a novel mechanism by which a family of adhesion molecules called αv integrins and the autophagy pathway limit excessive B cell responses to antigens containing TLR ligands and self-derived antigens.
Specifically, we have found that αvβ3 integrin regulates B cell TLR signaling by directing trafficking and maturation of TLR containing endosomes and engaging components of the autophagy pathway. When B cells lack either αv integrins or autophagy components LC3 and Atg5 endosomal trafficking of the TLRs is disrupted and leads to enhanced TLR signaling and increased B cell responses. We have used av conditional knockout mice to determine the consequences of loss of this αvβ3-mediated immune regulation. Mice lacking B cell av show increased antibody responses to antigens containing TLR-ligands and develop increased levels of autoantibodies.
We therefore propose that αv-mediated TLR regulation serves to maintain the balance between protective immunity to microbes and potential pathological autoimmune responses. We are currently studying the role of αv signaling and autophagy components in development of class switched, high affinity antibodies in response to antigens in the context of infection with a pathogen or in response to self-antigens.
Aberrant localized LTB4 production exacerbates methicillin-resistant Staphylococcus aureus skin infection in diabetic mice.
Authors: Brandt Stephanie L , Wang Soujuan , Carrasco Sebastian , Dejani Naiara , Glosson-Byers Nicole , Serezani Carlos Henrique 
Published: January 2023

Abstract
A major cause of severe skin infections is methicillin-resistant Staphylococcus aureus (MRSA). Immunotherapeutic strategies are needed to treat infections. Neutrophils and macrophages control MRSA skin infection but undue inflammation causes injury. The bioactive eicosanoid leukotriene B4 is a potent chemoattractant and enhances phagocyte effector functions in naïve mice. However we have shown that diabetic mice produce chronic LTB4 which promotes susceptibility to sepsis but the role of LTB4 in localized infections is unknown. We hypothesize that aberrant LTB4 drive excessive inflammation during MRSA skin infection in diabetics.
Diabetic mice at day 1 post infection had larger infected areas, bacterial and apoptotic cell burdens than nondiabetic controls. By intravital microscopy we observed more neutrophil recruitment in diabetic mice. These effects correlated with high levels of LTB4 and its receptor BLT1. At day 9 post infection nondiabetic mice were nearly healed but diabetic mice still had cell infiltration, high bacterial and apoptotic burdens, which associated with high levels of inflammatory mediators.
To test whether chronic LTB4 causes uncontrolled infection, diabetic mice were treated daily with a topical ointment containing BLT1 antagonist. The treatment reduced infection area, bacterial burden and neutrophil recruitment. We also detected fewer apoptotic cells and lower expression of inflammatory mediators. These findings reveal that LTB4 is detrimental for diabetics by chronically inducing a damaging inflammatory response. We observe that topical BLT1 antagonist treatment improves host defense in diabetic mice and promises to be an effective therapeutic to treat MRSA infections in diabetic patients.
Treatment with TLR4 agonists protect against infection after severe burn injury.
Authors: Bohannon Julia K , Luan Liming , Hernandez Antonio , Fensterheim Benjamin A , Patil Naeem , Guo Yin , Sherwood Edward 
Published: January 2023

Abstract
Infection is the leading cause of death in severely burned patients. Prophylactic treatment with the TLR4 agonist monophosphoryl lipid A (MPLA) induces resistance to subsequent bacterial challenge. Treatment of mice with MPLA enhances bacterial clearance, leading to improved survival in a model of P. aeruginosa burn wound infection. The current study was aimed to define the mechanisms responsible for improved bacterial clearance and survival in MPLA-treated burn-infected mice, and to determine if MPLA could protect against clinically relevant Gram positive and fungal pathogens. Mice underwent severe burn injury, followed by systemic treatment with MPLA or vehicle control for 2 days. Mice were then inoculated with P. aeruginosa topically or intraperitoneally, and responding neutrophils were measured in bone marrow, blood, burn wound and peritoneal cavity. In later experiments, burned mice were challenged systemically with S. aureus or C. albicans. MPLA treatment induced G-CSF production, decreased bone marrow neutrophil numbers and increased neutrophil numbers in the blood, peritoneal cavity and burn wound site. G-CSF was essential for MPLA-mediated survival, bacterial clearance and neutrophil trafficking. MPLA also improved survival against S. aureus and C. albicans systemic infections after burn. This suggests that G-CSF facilitates MPLA-induced trafficking of neutrophils, allowing for a more rapid response to sites of infection. The ability of MPLA to enhance antimicrobial responses and its ability to protect against a variety of clinically relevant pathogens make it an attractive therapeutic candidate for use in burn patients for the prevention of post-burn infections.
Type 2 inflammatory response protects against Staphylococcus aureus-induced sepsis
Authors: Krishack Paulette , Bubeck-Wardenburg Juliane , Sperling Anne I , Verhoef Philip 
Published: January 2023

Abstract
Sepsis is defined as new organ dysfunction due to acute infection and has a mortality rate &gt;20%. Recent studies indicate that type 2 cytokines, best known for their role in allergies, may be beneficial to the host during sepsis. We hypothesized that these responses protect against mortality during Staphylococcus aureus (S. aureus) induced sepsis.
We tested this hypothesis in 2 different mouse models, using either house dust-mite (HDM) sensitization and challenge to activate an adaptive type 2 response, or pre-treatment with IL-33 via intratracheal instillation to induce an innate type 2 response. This was followed by intravenous infection with S. aureus to induce sepsis. Pre-treatment with either HDM or IL-33 protected against S. aureus-induced mortality, indicating that activation of type 2 responses is beneficial during acute infection. Analysis of lung immune cell populations by flow cytometry revealed increased levels of type 2 innate lymphoid cells (ILC2) in mice pre-treated with HDM or IL-33 compared to untreated controls. Further, we found a relative decrease in lung neutrophils and an increase in lung eosinophils in type 2-stimulated compared to untreated mice, suggesting that type 2 responses may suppress an overwhelming neutrophilic response. However, systemic depletion of neutrophils prior to infection resulted in accelerated mortality compared to non-depleted mice, indicating that neutrophils are necessary to protect against S. aureus infection, and that augmented eosinophilia may confer protection against mortality. We conclude that the type 2 response is protective during sepsis, possibly due to the activity of ILC2s and a delicate balance of eosinophils and neutrophils in the inflamed lung.
mTOR deficiency reveals an immunological trade-off in innate resistance to mycobacterial infection in vivo
Authors: Pagan Antonio J , Levitte Steven , Berg Russell D , Hernandez Laura , Zimmerman Joseph , Tobin David M , Ramakrishnan Lalita 
Published: January 2023

Abstract
The Mechanistic Target of Rapamycin (mTOR) has been implicated in myeloid cell development and survival. As adequate myelopoiesis has been recently shown to be a resistance factor in tuberculosis, mTOR deficiency would be expected to increase mycobacterial growth and thus host susceptibility to this disease. In contrast, mTOR inhibition decreases Mycobacterium tuberculosis infection burdens in cultured macrophages, an effect attributed to the triggering of autophagy. Which of these contradictory effects of mTOR deficiency influences infection outcome in vivo is unknown. We have examined the effects of mTOR on mycobacterial infection using the optically transparent and genetically tractable Mycobacterium marinum-zebrafish model of tuberculosis. A forward genetic screen in zebrafish initially identified an mtor mutant as being hypersusceptible to M. marinum, a phenotype that mapped to mTOR complex 1 and was reproduced with rapamycin. However, using very low inoculums typical of human tuberculosis (1–3 mycobacteria) revealed mTOR’s dichotomous role: mTOR-deficient animals were more likely to clear infection early, but those that did not clear the infection progressed rapidly to more severe disease characterized by the death of infected macrophages and subsequent release of mycobacteria into the more growth-permissive extracellular space. Thus, mTOR supports macrophage homeostasis at the expense of a transient enhancement in microbicidal capacity that could reduce the likelihood of mycobacterial colonization but would inevitably thwart long-term immunity.