bluuebunny/crossref_metadata_2025_split huggingface dataset:
TLR9 regulates host defense via modulation of peritoneal B1 cell recruitment and functions during intra-abdominal sepsis.
Authors: Deng Meihong , Xu Li , Hoffmann Rosemary , Billiar Timothy R. 
Published: January 2023

Abstract

Background
Toll like receptor 9 (TLR9) is identified as anintracellular DNA receptor playing important roles in immunity. However, the mechanisms of how TLR9 regulates host defense are unclear. B1 cells are aninnate-like B cell population predominately residing in peritoneum and highly express TLR9. Therefore, we hypothesize that TLR9 may regulate host defense via modulation of peritoneal B1 pathobiology during sepsis.

Method
C57BL/6 (WT) mice and TLR9−/− mice were subjected to cecal ligation and puncture (CLP) with for 18 hours.

Result
Deletion of TLR9 increased survival as well as decreased bacterial load and systemic inflammation after CLP. Interestingly, peritoneal B1 cell numbers were significantly higher in TLR9−/− than WT mice, associated with significant increases of peritoneal CXCL13 level in TLR9−/− miceat baseline and after CLP. Strikingly, the expression level of CXCL13, a B cell-attracting chemokine, in the mesenteric adipo tissue was 50 fold higher inTLR9−/− than WT mice after CLP. Treatment with CXCL13 neutralizing antibody impaired bacterial clearance and decreased peritoneal B1 cell numbersin TLR9−/− mice compared to the IgG control after CLP, suggesting that TLR9 regulated B1 cell recruitment via CXCL13. Furthermore, deletion of TLR9 significantly increased peritoneal natural antibody IgM levels compared to WT at baseline and after CLP. Importantly, adoptive transfer of TLR9−/−B1 cells to WT mice improved bacterial clearance and increased peritoneal IgM levels compared to adoptive transfer of WT B1 cells after CLP.

Conclusions
These findings revealed an unrecognized role of TLR9 in modulating host defense via regulating B1 cell recruitment and IgM production during intra-abdominal sepsis.
Targeting the inflammasome as host directed therapy for Mycobacterium tuberculosis and HIV co-infection
Authors: Naqvi Kubra Fatima , Huante Matthew B. , Saito Tais , Chauhan Sadhana , Walker Aida , Lisinicchia Joshua , Gelman Benjamin , Endsley Janice J. 
Published: January 2023

Abstract
Mycobacterium tuberculosis (Mtb) infection continues to pose a significant public health threat with 1.3 million deaths occurring annually. People with HIV are among the most susceptible to Mtb infection due to the microbial synergism occurring during co-infection which promotes inappropriate inflammation as a potential driver of lung pathology. However, the immunomodulatory mechanisms driving pulmonary inflammation and pathogenesis are not fully understood. Our preliminary studies suggest that synergistic inflammasome activation within macrophages, the cellular host of both Mtb and HIV, leads to a caspase-1 dependent increase in pro-inflammatory cytokines. Using a humanized mouse model of co-infection developed in our laboratory, we have evaluated the in vivo inhibition of caspase-1 using the pro-drug VX-765 to limit mature IL-1β secretion and therefore reduce pulmonary inflammation. Treatment with VX-765 in humanized and WT (BALB/C) mice resulted in a decrease of lung inflammatory cytokine and chemokine production. Mycobacterial burden in the lung and sites of dissemination were unaffected by VX-765 treatment, suggesting inhibition of caspase-1 activity did not suppress protective immune responses. By using monocyte-derived macrophages (MDM) for an in vitro co-infection assay, we observed reduced inflammatory responses to co-infection following caspase-1 inhibition. These preliminary studies suggest a potential role of VX-765 as a host directed therapeutic targeting inflammasome activation in co-infected patients. With host directed therapy emerging as a possible new line of “anti-AIDS” therapy, the impact of these drugs on Mtb infection and the course of treatment is of great clinical importance.
Collagen, a major extracellular matrix component, promotes NLRP3 inflammasome-dependent and -independent IL-1β production.
Authors: Poudel Barun , Gurung Prajwal 
Published: January 2023

Abstract
Immune cell migration requires extracellular matrix (ECM) components that include collagen, fibronectin and laminin. As such ECM components regulate cellular processes including cell signaling, trafficking and differentiation. Excessive collagen production during disorders such as atherosclerosis, cancer, and renal and hepatic fibrosis has been known to have adverse immunological effects. However, the role of collagen in regulating inflammatory processes remain largely unexplored. Our data demonstrate that Nigericin-induced activation of the NLRP3 inflammasome in collagen-I-primed bone-marrow derived macrophages (BMDM) was not inhibited at chronic time points. In contrast, chronic TLR stimulation dampens ATP/Nigericin-induced NLRP3 inflammasome activation in BMDM. Collagen-I induced similar levels of pro-inflammatory cytokines TNF and IL-6 when compared to LPS-stimulated BMDM suggesting similar activation of signaling pathways. Moreover, our data demonstrate that chronic collagen-I stimulation was sufficient to induce IL-1β production in the absence of activating signals. This IL-1β production was dependent on the kinase activity of RIPK1 and RIPK3 but not the NLRP3 inflammasome. Current studies are focused on identifying, 1) mechanisms for chronic activation of the NLRP3 inflammasome and, 2) proteases that induce maturation and production of IL-1β in collagen-I treated BMDM. Altogether, our studies show that collagen-I can promote IL-1β production independently of NLRP3 inflammasome; however, in presence of Nigericin, collagen-I can chronically activate the NLRP3 inflammasome. Our study has the potential to identify novel targets to treat collagen-associated inflammatory disorders.
Id3 expression defines anatomically and functionally distinct regulatory T cells
Authors: Sullivan Jenna M. , Hoellbacher Barbara , Campbell Daniel J. 
Published: January 2023

Abstract
The Id (or inhibitor of DNA binding) proteins are small proteins that contain a helix-loop-helix domain and can heterodimerize with E-protein transcription factors. However, the Id proteins lack a DNA binding domain and act as natural dominant negatives of E-protein function. As a powerful transcriptional regulator, Id3 helps control the functional differentiation of CD8+ effector T cells and its expression is essential for regulatory T cell (TR) maintenance and function. Here we show that expression of Id3 is dynamically regulated in TR in a subset- and tissue-specific fashion. Within the TR compartment cTR (CD62LhiCD44lo) uniformly express Id3, however the eTR (CD62LloCD44hi) compartment can be further subdivided into Id3+ and Id3− eTR. Id3− eTR are found in low abundance in lymphoid tissues but are the majority of TR found in non-lymphoid tissue such as the skin and fat. These Id3− eTR express higher levels of inhibitory surface markers and have similar molecular profiles to the recently described ST2+ tissue TR. We propose that Id3 maintains a lymphoid-tissue TR phenotype and loss of Id3 promotes localization and retention of TR in non-lymphoid tissue.
SMAD4 impedes the conversion of NK cells into ILC1-like cells by curtailing non-canonical TGF-β signaling
Authors: Cortez Victor S. , Ulland Tyler K. , Cervantes-Barragan Luisa , Bando Jennifer K. , Robinette Michelle L. , Wang Qianli , White Andrew J. , Gilfillan Susan , Cella Marina , Colonna Marco 
Published: January 2023

Abstract
Among the characteristics that distinguish type 1 innate lymphoid cells (ILC1s) from natural killer (NK) cells is a gene signature indicative of ‘imprinting’ by cytokines of the TGF-β family. We studied mice in which ILC1s and NK cells lacked SMAD4, a signal transducer that facilitates the canonical signaling pathway common to all cytokines of the TGF-β family. While SMAD4 deficiency did not impact ILC1 differentiation, NK cells unexpectedly acquired an ILC1-like gene signature and were unable to control tumor metastasis or viral infection. Mechanistically, SMAD4 restrained non-canonical TGF-β signaling mediated by the cytokine receptor TGFβR1 in NK cells. NK cells from a SMAD4-deficient person were also hyper-responsive to TGF-β. These results identify SMAD4 as a previously unknown regulator that restricts non-canonical TGF-β signaling in NK cells.
Kinetics of the liver resident NK cell compartment
Authors: Dodard Garvin , Erick Timothy , Tata Angela , Brossay Laurent 
Published: January 2023

Abstract
The presence of tissue-resident NK (trNK) cells in the liver has only recently been appreciated. While the role of conventional NK cells (cNK) has been well-characterized, the trNK cell function is only beginning to be elucidated. Using the MCMV model of infection, we found that in contrast to liver cNK cells, trNK cells initially undergo a contraction phase followed by a recovery phase to homeostatic levels. The contraction phase is independent of the virus itself as a similar phenotype is observed following Poly I:C/CpG or α-GalCer injection. Interestingly, this initial contraction phase is independent of other liver lymphocyte subsets as it occurs even in infected lymphopenic animals, suggesting it is provoked by the inflammatory milieu. We also found that the contraction phase is partially due to cell apoptosis while the recovery phase occurs via proliferation in situ. These findings underscore the unique homeostatic properties and kinetics of liver resident NK cell compartment.
Transcription Factor TX Is Required for Liver-resident NK cells development
Authors: Song Jiaxi , Peng Hui , Zheng Xiaodong , Chen Yongyan , Wei Haiming , Sun Rui , Tian Zhigang 
Published: January 2023

Abstract
Hepatic NK cells are heterogeneous populations, consisting of DX5+CD49a− NK cells and CD49a+DX5− NK cells. CD49a+DX5− NK cells, also termed “tissue-resident NK (trNK) cells”, are distinct from DX5+CD49a− conventional NK (cNK) cells and possess unique hallmarks. Recent study shows that trNK cell differentiation is programmed by transcription factor T-bet, instead of Eomes, which is critical for cNK cell development. T-bet is highly expressed by both trNK and cNK cells, its deficiency leads to dramatic reduction of trNK cell and terminal mature cNK cells, suggesting a non-specific role of T-bet in the development of NK cell subsets.
To find a transcription factor that potentially impacts trNK cell development in a specific manner, we analyzed differentially expressed transcription factor genes between liver trNK and cNK cells by microarrays. We found that the transcription factor TX is expressed on liver trNK cells at much higher levels than on cNK cells. In order to figure out whether TX has an effect on liver trNK cells, we overexpressed TX on HSCs, and transferred the cells into lethally irradiated mice. Surprisingly, the frequency and number of liver trNK cells increased in TX-overexpressed mice. Then, we knocked down TX expression on HSCs, and transferred the cells to lethally irradiated mice. Although the frequency of liver trNK cells was invariant, the number decreased significantly. Therefore, these results suggest that the transcription factor TX affects liver trNK cells development, and the underlying mechanisms await further investigation.
Protection from lethal Staphylococcus aureus infection by probiotic exopolysaccharide
Authors: Paik Wonbeom , Alonzo Francis , Knight Katherine L. 
Published: January 2023

Abstract
Staphylococcus aureus is a bacterium that causes severe systemic infection with high mortality. Antibiotic resistance poses major problems for treatment of S. aureus infections, and novel therapeutics are needed. We previously showed that the probiotic Bacillus subtilis, produces an exopolysaccharide (EPS) that induces anti-inflammatory M2 macrophages. Transfer of EPS-induced M2 macrophages to naïve mice protects them from colitis due to an enteric pathogen. We tested if EPS could also protect from lethal S. aureus bloodstream infection. We treated mice with EPS before infection, and found that they survived and had reduced bacterial burden in the liver, and reduced levels of systemic inflammatory cytokines. We sought to determine the mechanism by which EPS protected the mice, and found that the EPS-induced M2 macrophages not only take-up S. aureus, but also inhibit the growth of S. aureus. We used an inhibitor of reactive oxygen species (ROS), and found that the growth inhibition of S. aureus by M2 macrophages was abrogated. In addition, we found that these M2 macrophages retain the capacity to inhibit activation of T cells by S. aureus supernatants which contain superantigens and numerous pro-inflammatory molecules. We suggest that the EPS-induced M2 macrophages represent “hybrid” macrophages capable of both M1- and M2-like functions, and could be used to protect hosts from lethal S. aureus infection by bolstering anti-bacterial immunity, while simultaneously limiting inflammation.
Type 3 interferons expressed in tuberculous granulomas may influence signaling in epithelioid macrophages
Authors: Mattila Joshua T. , Talukdar Priyanka , Junecko Beth A. 
Published: January 2023

Abstract
Type 3 interferons, also known as interferon lambda (IFNλ), play important roles in mucosal immunity and protection against viral infection, but their roles in tuberculosis (TB) remain to be investigated. IFNλ have properties that partially overlap with type 1 interferons (IFNα/β), a group of cytokines whose expression positively correlates with TB severity. Conversely, IFNλ can downregulate neutrophilic inflammation, and because neutrophils can be pathologic in TB, IFNλ may have currently-unappreciated protective effects. To better understand IFNλ expression in tuberculous lung granulomas, we performed RT-PCR analysis and immunohistochemistry on cynomolgus macaques with TB, a nonhuman primate with human-like pathology, to determine whether IFNλ is expressed in granulomas and to identify IFNλ-expressing cells at the site of disease. We found that mRNAs for the IFNλ isoforms IFNλ1 (IL-29), IFNλ3 (IL-28B), and IFNλ4 were expressed in normal lung tissue and granulomas, and there was a significant amount of heterogeneity in granuloma IFNλ expression. In normal lung tissue, IFNλ protein expression was most pronounced in ciliated epithelial cells, but there were differences in subcellular localization between isoforms. We identified differences in the subcellular localization of IFNλ4 in different granuloma macrophage subsets, with IFNλ4 in lymphocyte cuff-region macrophages present in the macrophage cytoplasm while in epithelioid macrophages, IFNλ4 was most abundant inside the macrophage nuclei. These data suggest that IFNλ4 may be differentially-expressed by granulomas macrophage subsets and have a previously-unappreciated signaling role in epithelioid macrophages.
Immune-Medicated Angiopoietin/Tie2 Expression and Renal Injury in Murine Orientia tsutsugamushi Infection Models
Authors: liu jinjun , Trent Brandon J. , Liang Yuejin , Brehm Tyler Y. , Xing Yan , Cai Jiyang , Sun Jiaren , Soong Lynn 
Published: January 2023

Abstract
Scrub typhus caused by O. tsutsugamushi infection is a life-threatening disease endemic in the Asia-Pacific region; however, its molecular pathogenesis remains unclear. Using new mouse models, we have reported that endothelial cell (EC)-targeted O. tsutsugamushi infection, acute tissue injury, and kidney bacterial persistency are pathological hallmarks, which mimic human scrub typhus. In this study, we focused on the regulation of vascular growth factor angiopoietin-1 (Ang1), its antagonist Ang2, and their specific Tie2 receptor in the kidneys of C57BL/6 mice. At D6 (disease onset) and D10 (prior to host death), infected kidneys had high Ang2/Ang1 ratio, but low Tie2 levels, and a progressive loss of glomerulus integrity. These renal injury signs were associated with increased influx of MPO+ neutrophils and CD3+T cells and expression of Th1 cytokines (TNF-α, IFN-γ, CXCL9) in the kidneys. Notable, we found a significant, time-dependent increase in alarmin expression (IL-33 and IL-36γ) preferentially in the kidneys, rather than in other organs, even though kidneys contained much lower bacterial loads than other organs. To test if host alarmin molecules contribute to disease severity, we compared pathology in lethally-infected WT and IL-33−/− mice, as well as rIL-33-injected WT mice. IL-33 deficiency promoted BCL2, Ang1, and eNOS expression and reduced cellular apoptosis in inflamed kidneys. In contrast, rIL-33 injunctions markedly exacerbated vascular stress and renal injury and increased host susceptibility to sublethal infection. Together, this study reveals that an immune-regulated expression of the Ang1/Tie2 axis can influence renal injury during infection. It helps understand the pathogenesis of severe scrub typhus.
Dysregulated Th1 Immune and Endothelial Responses during Severe Scrub Typhus
Authors: Soong Lynn , Trent Brandon J. , Xing Yan , Wei Yang , Liang Yuejin , Brehm Tyler Y. , Cho Nam-Hyuk , Cai Jiyang , Bouyer Donald H. , Sahni Sanjeev , Walker David H. , Sun Jiaren 
Published: January 2023

Abstract
We recently established murine Orientia tsutsugamushi infection models, which mimic immunological features of human scrub typhus. A hallmark of lethal Orientia infection is Th1-skewed, but Th2-impaired, immune responses, accompanied by endothelial dysfunction and multi-organ failure. Notably, while tissue bacterial loads peak at D6 (disease onset) in mice, lung neutrophil and CD8 T cell influx/activation reach peaks at D10 (prior to host death). We proposed a two-stage mechanism for disease pathogenesis: 1) Orientia replication in phagocytes and endothelial cells (EC) triggers inflammatory responses and host defense machinery; 2) infection-mediated release of DAMP molecules further exacerbates vascular damage, even after the control of bacterial replication. This hypothesis was supported by WB, qRT-PCR, and immunofluorescent co-staining of bacteria with leukocyte/EC/platelet-specific markers. During infection, progressive loss of vasculature and tight junctions (occludin, VE-cad, lectin positivity), vascular malfunction (reduced angiopoietin-1, Tie2, pTie2), and reduced CD41+ platelets in the lungs were positively linked to influx/activation of neutrophils and CD8 T cells, rather than bacterial loads. Immune dysregulation mechanisms were further examined by using infected human EC cultures, patient sera, IL-33−/− mice, and mouse macrophages/neutrophils. While Orientia infection can directly alter the angiopoietin/Tie2 axis in EC, endogenous IL-33/IL-36-like DAMPs contribute to vascular and tissue damage at the late stages. Our studies provide new insights into infection- vs. immune-mediated dysregulation and prognostic biomarkers, which will help the control of this neglected tropical disease.
Aryl hydrocarbon receptor activation differentially impacts Cholera toxin-specific IgA levels in feces and serum of male and female mice
Authors: Dekrey Gregory K. , King Aspen E. , Gawronska Eleanour , Metten Maddie R. 
Published: January 2023

Abstract
Secretory IgA plays a critical role in neutralizing enteric toxins and protecting against some intestinal pathogens. In mice, activation of the aryl hydrocarbon receptor (AhR) with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) has been shown to suppress antigen-specific systemic IgM and IgG responses, whereas the impact of AhR activation on mucosal IgA responses is less clear. Previous studies in our laboratory have demonstrated that Cholera toxin (CT)-specific fecal IgA levels in female mice are initially suppressed by TCDD exposure, but they recover to control levels within three weeks, unlike serum IgA levels. The goal of this study was to determine if TCDD exposure similarly alters CT-specific IgA levels in male mice. Male and female C57Bl/6 mice were administered peanut oil (vehicle) or TCDD on day 0, and each animal was immunized with CT (10 μg/Kg) on days 1, 8 and 15. Feces were collected on days 14 and 21, and antibody levels were measured by ELISA. Relative to controls at week 2, CT-specific fecal IgA levels were significantly decreased (P ≤ 0.05) by TCDD exposure at 40 μg/Kg (but not lower doses) in both male and female mice. Suppressed antibody levels persisted at 3 weeks in male mice only. In serum, significant suppression of CT-specific IgA was observed at week 3 in male mice (40 μg/Kg TCDD) and at week 4 in female mice (10 and 40 μg/Kg TCDD). These results suggest that antigen-specific fecal IgA responses in female mice recover from AhR-mediated suppression more rapidly than systemic responses and more rapidly than in male mice.
Fluid absorption modulates Peyer’s patch homeostasis and mucosal antibody responses
Authors: Chang Jonathan , Gressier Elise , Turley Shannon J. , Carroll Michael C. 
Published: January 2023

Abstract
Peyer’s patches (PPs) are B cell-rich lymphoid tissues situated throughout the small intestine which play an important role in mucosal antibody responses. PP architecture and stromal cell composition closely resemble that of peripheral lymph nodes despite geographical and functional differences. Notably, fibroblastic reticular cells (FRCs) located in small intestinal PPs form a network of collagen-rich reticular fibers similar to conduits found in lymph nodes. In the PP, these conduits extend from the basement membrane of the epithelial cell lining into the PP follicle, and terminate along blood and efferent lymphatic vessels.
Unlike lymph nodes, PPs lack a conventional source of afferent lymph that would normally contribute fluid flow through the conduit network. Instead fluid flow through PP conduits depends largely on water absorbed across the intestinal epithelium. We find that by disrupting water absorption, we can limit or prevent the contribution of absorbed lumenal fluids to the flow of PP conduits. Disruption of fluid absorption subsequently has profound effects on the structural integrity of the high endothelial venule (HEV) and surrounding perivascular FRCs. These alterations correlate with a striking defect in the recruitment of naïve lymphocytes to the PP.
Prolonged blockade of water absorption additionally impacts mucosal antibody responses. Antigen-specific fecal IgA titers are reduced, and germinal center responses are decreased in scale. These findings reveal a critical role for fluid absorption and conduit-mediated fluid flow in the maintenance of PP function and may have important implications for mucosal health under conditions of fluid malabsorption, long-term laxative use, and diarrhoeal diseases.