Coxsackievirus B3 regulates macrophage polarization through ANXA3 to promote the development of myocarditis.

Abstract

BACKGROUND: Viral myocarditis (VMC) is a common inflammatory disease in children that is caused mainly by Coxsackievirus B3 (CVB3) infection. M1 macrophage polarization is a key pathological event in the progression of CVB3-induced myocarditis, and annexin 3 (ANXA3) plays an important role in the process of macrophage activation. Therefore, this study aimed to investigate the function of ANXA3 in CVB3-induced myocarditis and macrophage polarization. METHODS: CVB3-challenged mice were used to establish a CVB3-induced myocarditis model, and the polarization of RAW264.7 cells was induced by CVB3 infection. The expression of genes and proteins was detected by RT-qPCR, western blotting, immunohistochemistry, immunofluorescence, and ELISA. The pathological lesions in the cardiac tissue were detected by HE staining. Serum levels of myocardial injury markers were detected using kits. RESULTS: We found that ANXA3 expression was increased in VMC. ANXA3 knockdown hindered the progression of CVB3-induced VMC, as manifested by increased body weight, reduced inflammatory cell infiltration in the heart, and decreased serum levels of myocardial injury markers (LDH, CK, CK-MB and cTnI). ANXA3 knockdown also inhibited the M1 polarization of CVB3-infected mouse heart tissue macrophages and RAW264.7 cells in vitro and reduced the levels of the inflammatory cytokines IL-1β, IL-6, and TNF-α. In addition, CVB3 infection promoted the expression of TLR4, MyD88, and p-IκB-α in mouse heart tissues and RAW264.7 cells and the nuclear transfer of NF-κB p65 and inhibited the expression of IκB-α. Mechanistic studies revealed that CVB3 increased ANXA3 expression by activating the TLR4/MyD88 pathway, thereby promoting NF-κB p65 nuclear translocation and the subsequent M1 polarization of macrophages, eventually leading to the development of CVB3-induced myocarditis. CONCLUSION: Our study elucidated the role of ANXA3 in promoting CVB3-induced myocarditis, providing a potential intervention target for the treatment of VMC.