Viral myocarditis (VMC) is a type of cardiac inflammation that is generally caused by coxsackievirus B3 (CVB3) infection. Several MicroRNAs (miRNAs) are known to play crucial roles in VMC pathogenesis. MiR-15 is reportedly associated with myocardial injury, inflammatory responses and viral infection. Whether miR-15 affects the occurrence and development of VMC remains largely unknown. The roles of miR-15 and their underlying mechanisms in CVB3-stimulated H9c2 cells were assessed in this study. We infected H9c2 cells with CVB3 to establish a VMC cellular model. We then determined the effects of miR-15 inhibition on three cardiomyocyte injury markers: lactate dehydrogenase (LDH), creatine kinase-MB (CK-MB) and cardiac troponin-I (cTn-I). The impact on CVB3-induced cell apoptosis and pro-inflammatory cytokines was also investigated. The effects of miR-15 inhibition on NLRP3 inflammasome activation were also assessed. The target relationship between miR-15 and NOD-like receptor X1 (NLRX1) was determined using a luciferase reporter assay. MiR-15 expression was significantly upregulated in H9c2 cells after CVB3 infection. Inhibition of miR-15 significantly decreased the CVB3-induced levels of LDH, CK-MB and cTn-I. It also elevated cell viability, reduced CVB3-induced cell apoptosis and decreased the generation of the interleukins IL-1β, IL-6 and IL-18. Furthermore, we determined that miR-15 inhibition suppressed NLRP3 inflammasome activation by downregulating NLRP3 and caspase-1 p20 expression. We found a direct target relationship between miR-15 and NLRX1. Additionally, inhibition of NLRX1 reversed the protective effects of miR-15 inhibition against CVB3-induced myocardial cell injury by regulating the NLRP3 inflammasome. Our results indicate that miR-15 inhibition alleviates CVB3-induced myocardial inflammation and cell injury. This may be partially due to NLRX1-mediated NLRP3 inflammasome inactivation.

中文翻译：

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抑制 microRNA-15 通过靶向 NLRX1 调节 NLRP3 炎性体来保护 H9c2 细胞免受 CVB3 诱导的心肌损伤。

病毒性心肌炎 (VMC) 是一种心脏炎症，通常由柯萨奇病毒 B3 (CVB3) 感染引起。已知几种 MicroRNA (miRNA) 在 VMC 发病机制中起关键作用。据报道，MiR-15 与心肌损伤、炎症反应和病毒感染有关。miR-15是否影响VMC的发生和发展仍然很大程度上未知。本研究评估了 miR-15 的作用及其在 CVB3 刺激的 H9c2 细胞中的潜在机制。我们用 CVB3 感染 H9c2 细胞以建立 VMC 细胞模型。然后我们确定了 miR-15 抑制对三种心肌细胞损伤标志物的影响：乳酸脱氢酶 (LDH)、肌酸激酶-MB (CK-MB) 和心肌肌钙蛋白-I (cTn-I)。还研究了对 CVB3 诱导的细胞凋亡和促炎细胞因子的影响。还评估了 miR-15 抑制对 NLRP3 炎性体活化的影响。使用荧光素酶报告基因测定确定 miR-15 和 NOD 样受体 X1 (NLRX1) 之间的靶标关系。CVB3感染后H9c2细胞中MiR-15表达显着上调。抑制 miR-15 显着降低了 CVB3 诱导的 LDH、CK-MB 和 cTn-I 水平。它还提高了细胞活力，减少了 CVB3 诱导的细胞凋亡并减少了白细胞介素 IL-1β、IL-6 和 IL-18 的产生。此外，我们确定 miR-15 抑制通过下调 NLRP3 和 caspase-1 p20 表达来抑制 NLRP3 炎性体活化。我们发现了 miR-15 和 NLRX1 之间的直接靶标关系。此外，抑制 NLRX1 通过调节 NLRP3 炎性体逆转了 miR-15 抑制对 CVB3 诱导的心肌细胞损伤的保护作用。我们的结果表明，抑制 miR-15 可减轻 CVB3 诱导的心肌炎症和细胞损伤。这可能部分是由于 NLRX1 介导的 NLRP3 炎性体失活。