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Although IL-17 is considered to promote B cell differentiation into antibody-secreting plasma cells in some autoimmune diseases, its mechanism remains unclear. Recent studies revealed that autophagy, a lysosome-mediated catabolic process for providing nutrients under starvation, could regulate plasma cell homeostasis, so this study aimed to explore whether and how autophagy participates in IL-17-mediated plasma cell differentiation by MyHC-α-induced experimental autoimmune myocarditis (EAM) mouse model. It showed that IL-17 could not only induce B cell autophagy, but also facilitate the myocarditis severity, serum anti-MyHC-α autoantibody production and splenic CD38(+) CD138(+) B cell percentages, while the autophagy inhibitor 3-methyladenine attenuated these effects. Furthermore, serum anti-MyHC-α IgG autoantibody productions and CD38(+) CD138(+) B cell percentages were positively correlated with B cell autophagy levels respectively. In vitro, we further revealed that IL-17 could directly promote B cell autophagy, which boosted Blimp-1 expressions and CD38(+) CD138(+) B cell percentages. Moreover, elevated autophagy mediated by IL-17 enhanced ubiquitin-proteasome system activity and B cell anti-apoptotic ability by Beclin-1 and p62 through Erk1/2 phosphorylation, and these changes brought by IL-17 could be also inhibited with 3-methyladenine. Therefore, we concluded that autophagy contributed to IL-17-mediated plasma cell differentiation by regulating Blimp-1 expression and Beclin-1/p62 associated B cell apoptosis in EAM., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Aims: Th17 cells contributed to myocardial inflammatory injury in acute viral myocarditis (AVMC), and the migration of these cells were mainly mediated by CCL20-secreting inflammatory cells. However, whether and how the resident cells such as cardiomyocytes and cardiac fibroblasts could mediate Th17 cell migration into the heart remains unclear in AVMC., Methods: The effect of CCL20 on the dynamic alterations of intracardiac Th17 cells and disease severity were investigated through the neutralization of CCL20 in AVMC mice. The key cells releasing CCL20 in the heart and the effects of CCL20-secreting cells on Th17 cell arrest, migration and differentiation were detected in vitro., Results: Neutralization of CCL20 efficiently repressed the myocardial inflammation along with the reduction of Th17 cell infiltrations in the course of AVMC. In vitro, after stimulations of TNF-α, IL-1β and IL-17, cardiac fibroblasts rather than cardiomyocytes could be dominantly induced for CCL20 production. CCL20-secreting cardiac fibroblasts boosted Th17 cell arrest on endothelium, and induce Th17 cell migration. However, CCL20 produced by cardiac fibroblasts had no effect on Th17 cell differentiation and IL-17 production., Conclusions: It firstly suggested that cardiac fibroblasts could recruit Th17 cells infiltration into myocardium by secreting CCL20 in AVMC., (© 2013 S. Karger AG, Basel.)

Acute viral myocarditis (AVMC) is characterized by virus-triggered myocardial inflammation, and Coxsackievirus B3 (CVB3) is the primary pathogen. We previously proved that Th17 cells, besides having proinflammatory effects, were involved in AVMC by enhancing humoral response. However, the relationship between Th17 cells and CVB3 replication remains unknown. In this experiment, we infected BALB/c mice with CVB3 for establishing AVMC models and then found that, with the increase of viral replication, the expressions of splenic Th17 cells, serum IL-17, and cardiac IL-17 mRNA were elevated significantly, accompanied by the progressive cardiac injuries of AVMC. Furthermore, on day 5, the peak time for viral replication, correlation was positive between cardiac IL-17 mRNA and CVB3 RNA (correlation index = 0.835; p < 0.01). Although the expressions of Th1 and CD8(+) T cells, which could secrete the antiviral cytokine IFN-γ and damage the heart, were also elevated, along with Th17 cells, in AVMC, the neutralization of IL-17 further upregulated the percentages of splenic Th1 and CD8(+) T cells and the levels of cardiac IFN-γ mRNA. The cardiac pathological changes were obviously improved after neutralization, with reduced viral replication followed by decreases in the cardiac inflammatory cytokines IL-17, TNF-α, and IL-1β. These data suggest that Th17 cells contribute to CVB3 replication in AVMC, and that IL-17 might be an important target for regulating the balance of antiviral immunities.

Background: Recently, the Th17 cell, a newly determined CD4+Th subset, was reported to participate in the inflammation of myocarditis combined with Th1 cells, and this study aimed to explore whether it was involved in the Th2 cell-mediated humoral immunity in viral myocarditis., Methods: A total of 34 patients, including 16 acute viral myocarditis (AVMC) and 18 dilated cardiomyopathy (DCM) having a history of AVMC, were enrolled for this study besides 18 healthy volunteers., Results: The frequencies of Th17 and Th1 cells, especially Th17 cells in AVMC patients, while those of Th1 and Th2 cells, especially Th2 cells in DCM group, were all increased significantly compared with those in healthy volunteers (P < 0.01), with no changes of Th2 cells in AVMC and Th17 cells in DCM groups. The similar results were also observed in Th cell cytokines (IL-17, INF-gamma, and IL-4) and key transcript factors (RORgammat, T-bet, and GATA-3). Meanwhile, antiheart antibodies (AHA) of IgG type were found in 15 (93.8%) patients with AVMC and ten (55.6%) cases with DCM, accompanied by the higher expression of IL-17R on B cells and the frequencies of B cells than those in healthy controls (P < 0.01 in AVMC and P < 0.05 in DCM, respectively) who had no AHA. Furthermore, both of the B cell activities in AVMC and DCM groups were elevated and positively correlated to serum IL-17 (R = 0.66, P < 0.01) and IL-4 (R = 0.47, P < 0.05) respectively, with no correlation to INF-gamma., Conclusions: It was Th17 cells but not Th2 cells that helped the B cells to produce AHA in AVMC and not until at the late phase of viral myocarditis could Th2 cells play the important role in mediating humoral response.

Anti-adenine nucleotide translocator (ANT) autoantibodies are related to the development of Coxsackievirus B3 (CVB3)-triggered acute viral myocarditis (AVMC). Recently, studies suggested that IL-17 especially produced by a novel CD4(+) Th-cell subset Th17 cells contributed to the production of pathogenic autoantibodies in some autoimmune diseases. However, the pathogenic role of IL-17 in AVMC remains largely unknown. In this study, we investigated whether IL-17 was associated with the disease progression and the production of anti-ANT autoantibodies in AVMC mouse model. The results showed that IL-17 monoclonal antibody (mAb)-treated AVMC mice had decreased HW/BW, reduced serum CK-MB activity and improved pathological score of heart sections along with the reduction of circulating IL-17 level and serum anti-ANT autoantibodies. The correlation index of serum IL-17 concentration and anti-ANT-autoantibody level was 0.874, p<0.01. In addition, the experimental results in vitro further proved that IL-17mAb could inhibit the proliferation of CD19(+) B lymphocytes and the secretion of anti-ANT autoantibodies. Our data suggested that IL-17 was related to the disease progression in AVMC mouse model by regulating the production of autoantibodies and blocking IL-17 might represent a promising novel therapeutic approach., (Copyright 2009 Elsevier B.V. All rights reserved.)