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Aims: This work aimed to evaluate the regulatory function of IL-10-producing B cells in viral myocarditis (VMC)., Main Methods: We adoptively transferred purified IL-10-producing B cells to VMC mice via the tail vein. We observed the inflammatory responses and cardiac lesions by histological analysis, examined the proportions of spleen Th1 and T17 cells by flow cytometry and expression levels of related transcription factors (T-bet and RORγt) by reverse transcription polymerase chain reaction (RT-PCR), and calculated the cardiac pathological scores and the mean survival times., Key Findings: IL-10-producing B cells were found to be T cell-dependent in the pathogenesis of VMC. They mainly downregulated T-bet and RORγt mRNA levels to decrease the proportions of Th1 and Th17 cells, thereby restraining the inflammation and damage in the myocardium in B cell-deficient VMC mice. Adoptive transfer of IL-10-producing B cells before VMC induction also normalized the inflammatory responses and prolonged the survival time in wild-type (WT) VMC mice. While the transfer of IL-10-producing B cells on day 3 of VMC alleviated the severity of disease, it did not extend the mean survival time of VMC mice. By contrast, IL-10-producing B cells showed no effect on day 7 of VMC. In conclusion, IL-10-producing B cells downregulate the proportion of Th1 and Th17 cells to alleviate inflammatory damage in the myocardium during VMC before the induction or the early phase of disease., Significance: These findings suggest that IL-10-producing B cells may be a new therapeutic target for modulating the immune response in VMC., (Copyright © 2019 Elsevier Inc. All rights reserved.)

The role of B cells in viral myocarditis (VMC) remains controversial. In order to establish a role and mechanism of action for B cells in acute VMC, we established an acute VMC mouse model by intraperitoneal injection of Coxsackie virus group B type 3 (CVB3). At day 7, mice were analyzed using myocardial histopathology, and the presence of M2 macrophages in spleen and heart. Mice were divided into four groups, all having a C57BL/6 background: control group; wild-type (WT) VMC; mMt/mMt (-/-) VMC (BKO), and BKO + B cell VMC. A role for B cells was demonstrated by a significant reduction in myocardial pathological score and an increase in the frequency of M2 macrophages in the BKO group, when compared to the WT group. Once BKO mice underwent B cell reconstitution with isolated WT B cells, the myocardial pathological score was increased significantly, while the frequency of M2 macrophages decrease. Our findings demonstrate that B cells increase myocardial inflammation by suppressing M2 polarization in acute VMC in vivo.

TGF-β1 has long been considered as a key mediator in diabetic kidney disease (DKD) but anti-TGF-β1 treatment fails clinically, suggesting a diverse role for TGF-β1 in DKD. In the present study, we examined a novel hypothesis that latent TGF-β1 may be protective in DKD mice overexpressing human latent TGF-β1. Streptozotocin-induced Type 1 diabetes was induced in latent TGF-β1 transgenic (Tg) and wild-type (WT) mice. Surprisingly, compared to WT diabetic mice, mice overexpressing latent TGF-β1 were protected from the development of DKD as demonstrated by lowing microalbuminuria and inhibiting renal fibrosis and inflammation, although blood glucose levels were not altered. Mechanistically, the renal protective effects of latent TGF-β1 on DKD were associated with inactivation of both TGF-β/Smad and nuclear factor-κB (NF-κB) signaling pathways. These protective effects were associated with the prevention of renal Smad7 from the Arkadia-induced ubiquitin proteasomal degradation in the diabetic kidney, suggesting protection of renal Smad7 from Arkadia-mediated degradation may be a key mechanism through which latent TGF-β1 inhibits DKD. This was further confirmed in vitro in mesangial cells that knockdown of Arkadia failed but overexpression of Arkadia reversed the protective effects of latent TGF-β1 on high glucose-treated mesangial cells. Latent TGF-β1 may protect kidneys from TGF-β1/Smad3-mediated renal fibrosis and NF-κB-driven renal inflammation in diabetes through inhibiting Arkadia-mediated Smad7 ubiquitin degradation.

Objectives: Bone marrow-derived cells (BMCs) have recently been identified to play a vital role in repairing damaged myocardium; however, it is not known whether or not mobilization of BMCs is involved in the pathogenesis of acute viral myocarditis (VMC). Thus, we analyzed the expression of CD45+CD34+VLA-4+ cells and vascular cell adhesion protein-1 (VCAM-1) in a murine model of acute VMC. Methods: Male BALB/c mice were intraperitoneally infected with coxsackievirus B3 to establish acute VMC. The frequency of CD45+CD34+VLA-4+ cells in the heart, peripheral blood, and bone marrow was examined by flow cytometry 3, 7, 14, and 28 days after injection. Cardiac VCAM-1 and pathology scores were determined by immunohistochemistry, and myocardial VCAM-1, IL-1β, and TNF-α were analyzed by RTPCR and Western blot. Results: In mice with acute VMC, the CD45+CD34+VLA-4+ cell population in the heart was significantly increased by day 7 and then decreased; in contrast, the CD45+CD34+VLA-4+ cell population decreased in the bone marrow and peripheral blood by day 3 and then increased. High expression of VCAM-1 was detected in the heart in parallel with CD45+CD34+VLA-4+ cell expression. Conclusions: In mice with acute VMC, VCAM-1-induced CD45+CD34+VLA-4+ cell mobilization into the injured heart is involved in the repair of injured myocardium. [ABSTRACT FROM AUTHOR]

Viral myocarditis (VMC) is a common cardiovascular disease, and microRNAs (miRNAs) have been postulated to be involved in its pathology. Using microarrays, we observed that miRNA-21 and -146b were upregulated in a murine model of VMC. We also found that miRNA-451 was downregulated. In vivo silencing of miRNA-21 and -146b resulted in less-severe VMC. Overexpression of miRNA-451 did not ameliorate the severity of VMC. Further work revealed that inhibition of miRNA-21 and -146b decreased the expression levels of Th17 and RORγt . Overexpression of miRNA-451 had no effect on IL-17 and RORγt expression. Inhibition of miRNA-21 and -146b might ameliorate myocardium inflammation by mediating downregulation of RORγt expression, indicating that these miRNAs are involved in the pathogenesis of murine VMC. [ABSTRACT FROM AUTHOR]

Background: Recently, some studies indicate that interleukin (IL)-17, known as a T cell (Th17)-derived proinflammatory cytokine, is the major mediator of tissue inflammation in inflammatory and autoimmune diseases. Viral myocarditis (VMC) is a T cell-mediated autoimmune disease, but the role for IL-17 in VMC is not well defined. Results: Using IL-17 monoclonal antibody (IL-17mAb)-treated VMC mice, we tested the pathogenic role of IL-17 in the development of VMC. VMC mice were treated with monoclonal rat anti-murine IL-17 antibody (anti-IL-17) or rat IgG2A isotype control or phosphate-buffered solution 3 days after Coxsackievirus B3 (CVB3) injection. Normal mice without any manipulation were taken as normal control. The survival rates of mice were monitored and heart pathology was examined histologically. IL-17, IL-6, and TNF-α mRNA of the myocardium were assessed by semiquantitative RT-PCR. Systemic IL-17, IL-6, and TNF-α level were measured by enzyme-linked immunosorbent assay, and local myocardium IL-17 expression was analyzed using immunohistochemical staining. Flow cytometric analysis was used to evaluate the frequencies of Th17 subsets in CD4+T cells. Results showed that neutralization of IL-17 with anti-IL-17 can ameliorate clinical symptoms, defer disease course, decrease serum IL-17 level, without declining the IL-17, IL-6 and TNF-α mRNA transcript level and serum IL-6, TNF-α level. The differentiation and proliferation of the Th17 cells were unchanged. Conclusions: Our data suggest that IL-17 is crucially involved in the pathogenesis of murine VMC, IL-17 inhibition might ameliorate the myocardium inflammation after the onset of VMC. [ABSTRACT FROM AUTHOR]

Background: Secondary brain damage caused by the innate immune response and subsequent proinflammatory factor production is a major factor contributing to the high mortality of intracerebral haemorrhage (ICH). Nucleotide-binding oligomerization domain 1 (NOD1)/receptor-interacting protein 2 (RIP2) signalling has been reported to participate in the innate immune response and inflammatory response. Therefore, we investigated the role of NOD1/RIP2 signalling in mice with collagenase-induced ICH and in cultured primary microglia challenged with hemin.Methods: Adult male C57BL/6 mice were subjected to collagenase for induction of ICH model in vivo. Cultured primary microglia and BV2 microglial cells (microglial cell line) challenged with hemin aimed to simulate the ICH model in vitro. We first defined the expression of NOD1 and RIP2 in vivo and in vitro using an ICH model by western blotting. The effect of NOD1/RIP2 signalling on ICH-induced brain injury volume, neurological deficits, brain oedema, and microglial activation were assessed following intraventricular injection of either ML130 (a NOD1 inhibitor) or GSK583 (a RIP2 inhibitor). In addition, levels of JNK/P38 MAPK, IκBα, and inflammatory factors, including tumour necrosis factor-α (TNF-α), interleukin (IL)-1β, and inducible nitric oxide synthase (iNOS) expression, were analysed in ICH-challenged brain and hemin-exposed cultured primary microglia by western blotting. Finally, we investigated whether the inflammatory factors could undergo crosstalk with NOD1 and RIP2.Results: The levels of NOD1 and its adaptor RIP2 were significantly elevated in the brains of mice in response to ICH and in cultured primary microglia, BV2 cells challenged with hemin. Administration of either a NOD1 or RIP2 inhibitor in mice with ICH prevented microglial activation and neuroinflammation, followed by alleviation of ICH-induced brain damage. Interestingly, the inflammatory factors interleukin (IL)-1β and tumour necrosis factor-α (TNF-α), which were enhanced by NOD1/RIP2 signalling, were found to contribute to the NOD1 and RIP2 upregulation in our study.Conclusion: NOD1/RIP2 signalling played an important role in the regulation of the inflammatory response during ICH. In addition, a vicious feedback cycle was observed between NOD1/RIP2 and IL-1β/TNF-α, which could to some extent result in sustained brain damage during ICH. Hence, our study highlights NOD1/RIP2 signalling as a potential therapeutic target to protect the brain against secondary brain damage during ICH. [ABSTRACT FROM AUTHOR]