目的:病毒感染是心肌炎的主要原因。除了急性心脏并发症,晚期后遗症,如心肌纤维化可能发展,重要影响预后。柯萨奇病毒B3(CVB)诱导的小鼠心肌炎是研究病毒性心肌炎最常用的转化模型,并提供了我们目前对该疾病病理生理学的大部分理解。然而,疾病的晚期阶段,包括纤维发生和心律失常发生,迄今为止,在病毒性心肌炎研究中被低估了。本研究调查了C57BL/6J小鼠中CVB诱导的心肌炎的自然史,将重点扩展到疾病的急性期之外。此外,我们研究了性别和接种剂量对病程的影响。
结果:C57BL/6J小鼠(12周龄;n=154)接受单次腹腔注射CVB诱发病毒性心肌炎,或载体(PBS)作为对照。雄性小鼠(n=92)注射5×105(常规剂量)(RD)或5×106(高剂量)(HD)斑块形成单位的CVB,而雌性小鼠只接受RD。在CVB或PBS注射后1、2、4、8和11周处死动物。接种病毒的小鼠发展为病毒性疾病,一般状况和体重减轻暂时下降,这在雌性动物中不太明显(P<0.001)。在雄性CVB小鼠中,过早死亡发生在接种后第8-23天(RD:21%,HD:20%),而所有雌性动物都存活了下来。在疾病的过程中,心脏炎症逐渐消退,在雌性小鼠中具有更快的分辨率。在炎性细胞浸润物的组成方面没有实质性的组差异:在第7天和第14天细胞毒性T细胞占优势,并且在第7天至第14天从精氨酸酶1反应性巨噬细胞转变为iNOS反应性巨噬细胞是主要发现。伴随着不同模式的心肌纤维化的发展和成熟,增强了雄性小鼠的纤维形成。到第14天,病毒几乎完全从心脏清除。在疾病的急性期,心脏损伤的血清生物标志物和心脏重塑基因的表达暂时升高。在雌性CVB动物中,心脏CTGF基因上调的持续时间较短。第8周和第11周的体内电生理学研究表明,在基线条件下(即不存在致心律失常药物),室性心律失常只能在CVB动物中诱发。CVB组和对照组在整个刺激方案中的累积心律失常负担没有显着差异。
结论:在C57BL/6J小鼠中接种CVB代表急性自限性病毒性心肌炎的模型,进展为不同的心肌纤维化模式。性,但不是接种剂量,似乎调节了疾病的进程。
OBJECTIVE: Viral infections are the leading cause of myocarditis. Besides acute cardiac complications, late-stage sequelae such as myocardial fibrosis may develop, importantly impacting the prognosis. Coxsackievirus B3 (CVB)-induced myocarditis in mice is the most commonly used translational model to study viral myocarditis and has provided the majority of our current understanding of the disease pathophysiology. Nevertheless, the late stages of disease, encompassing fibrogenesis and arrhythmogenesis, have been underappreciated in viral myocarditis research to date. The present study investigated the natural history of CVB-induced myocarditis in C57BL/6J mice, expanding the focus beyond the acute phase of disease. In addition, we studied the impact of sex and inoculation dose on the disease course.
RESULTS: C57BL/6J mice (12 weeks old; n=154) received a single intraperitoneal injection with CVB to induce viral myocarditis, or vehicle (PBS) as control. Male mice (n=92) were injected with 5 × 105 (regular dose) (RD) or 5 × 106 (high dose) (HD) plaque-forming units of CVB, whereas female mice received the RD only. Animals were sacrificed 1, 2, 4, 8, and 11 weeks after CVB or PBS injection. Virally inoculated mice developed viral disease with a temporary decline in general condition and weight loss, which was less pronounced in female animals (P<.001). In male CVB mice, premature mortality occurred between days 8 and 23 after inoculation (RD: 21%, HD: 20%), whereas all female animals survived. Over the course of disease, cardiac inflammation progressively subsided, with faster resolution in female mice. There were no substantial group differences in the composition of the inflammatory cell infiltrates: predominance of cytotoxic T cells at day 7 and 14, and a switch from arginase1-reactive macrophages to iNOS-reactive macrophages from day 7 to 14 were the main findings. There was concomitant development and maturation of different patterns of myocardial fibrosis, with enhanced fibrogenesis in male mice. Virus was almost completely cleared from the heart by day 14. Serum biomarkers of cardiac damage and cardiac expression of remodeling genes were temporarily elevated during the acute phase of disease. Cardiac CTGF gene upregulation was less prolonged in female CVB animals. In vivo electrophysiology studies at weeks 8 and 11 demonstrated that under baseline conditions (i.e. in the absence of proarrhythmogenic drugs), ventricular arrhythmias could only be induced in CVB animals. The cumulative arrhythmia burden throughout the entire stimulation protocol was not significantly different between CVB and control groups.
CONCLUSIONS: CVB inoculation in C57BL/6J mice represents a model of acute self-limiting viral myocarditis, with progression to different patterns of myocardial fibrosis. Sex, but not inoculation dose, seems to modulate the course of disease.