白介素-17A介导的自噬调控在压力超负荷诱导心肌肥厚中的作用及机制研究

Previous studies have demonstrated that the change of cardiomyocyte autophagic activity may play an important role in the development and progression of myocardial hypertrophy. Accumulating evidence indicates that proinflammatory cytokine interleukin-17A (IL-17A) contribute to the regulation of autophagic activity of some cell types. Our preliminary study firstly demonstrated that blocking IL-17A could reduce the autophagic activity of myocardium, attenuate pressure over-load induced myocardial hypertrophy, and improve cardiac diastolic function. These data suggested that IL-17A may promote the progression of cardiomyocytes and myocardial hypertrophy by enhance the autophagic activity of cardiomyocytes, while the underlying mechanisms were still unknown. Our group has established mice transverse aortic constriction (TAC) model to induce pressure over-load, the aims of the present study include: 1) to investigate the IL-17A expression, autophagic activity of myocardium, and cardiac hypertrophy after TAC at different time points; and to determine the roles of IL-17A play in the pressure over-load induced myocardial hypertrophy by blocking or enhance the effect of IL-17A using IL-17A gene knockout mice, anti-IL-17A antibody or cytokines. 2) Using hypertrophic cardiomyocytes models induced by angiotensin II or isoproterenol incubations to reveal the effects of IL-17A exerts on autophagy or hypertrophy of cardiomyocytes and related potential mechanisms using RNA interference technology. Our findings may yield potential therapeutic targets for regression of myocardial hypertrophy and prevention of heart failure.

心肌细胞自噬活性的变化在心肌肥厚的发生发展中起重要作用。研究发现，促炎症因子白介素-17A（IL-17A）能够调控细胞的自噬活性。我们前期研究首次发现，阻断IL-17A能够显著降低心肌组织的自噬活性，减轻压力超负荷诱导的心肌肥厚，改善舒张功能，提示IL-17A可能通过调控心肌细胞的自噬活性，加速心肌肥厚和心力衰竭的发展，但具体机制尚不清楚。本课题组拟以主动脉缩窄（TAC）小鼠模型模拟压力超负荷，明确小鼠TAC术后IL-17A表达、心肌的自噬活性及心肌肥厚的变化规律，应用IL-17A基因敲除、抗IL-17A中和抗体阻断或细胞因子增强IL-17A的效应，揭示IL-17A在心肌肥厚中的作用和对自噬活性的影响。血管紧张素II和异丙肾上腺素孵育诱导心肌细胞肥大模型，应用RNA干扰等技术明确IL-17A对心肌细胞的自噬活性和肥大的影响和具体分子机制。该研究将有助于发现逆转心肌肥厚和预防心衰的新靶点。

心肌细胞自噬活性的变化在心肌肥厚的发生发展中起重要作用，而已有研究证明促炎症因子白介素-17A（IL-17A）能够调控细胞的自噬活性。本课题组通过研究证实：⑴IL-17A基因敲除改善压力超负荷小鼠的心脏肥厚、心肌纤维化及舒张功能不全，降低MMP2、MMP9 mRNA表达和活性，降低心肌的自噬活性。IL-17A基因敲除改善心脏舒张功能的机制可能为调控MMPs/TIMPs系统的平衡和心肌自噬活性。⑵通过IL-17A细胞因子干预可加重压力超负荷下的心肌肥厚，心肌纤维化和舒张功能障碍，降低心肌微血管密度，但不影响心肌细胞凋亡；通过Western-blot和实时荧光定量RT-PCR分析发现，自噬相关蛋白LC3 II/LC3 I比值，Beclin1和ATG5 mRNA表达均升高；通过自噬抑制剂3-MA干预能改善心肌肥厚和心脏舒张功能等指标。在细胞水平，IL-17A处理呈剂量依赖性激活H9C2心肌细胞自噬。⑶转录组学研究发现，IL-17A干预后心肌组织基因表达显著上调17个（Col1a1、Kif1a、Cnmd、Pamr1、Postn、Col11a1、Uchl1、A2m、Pde3b、Itgbl1、Prss35、Cilp、Tent5c、Hamp、Sv2c、Tubb4a、Ccr5），显著下调11个（Slfn4、Lcn2、Sord、Ifi44、Fbxo44、Ifit1、Isg15、Ifit2、Oas1a、Ifit3、Strit1）。其中与自噬调控密切相关基因包括Col1a1、Kif1a、Lcn2、Uchl1、Isg15、CCR5等。KEGG分析结果提示，IL-17A诱导的自噬调控可能与细胞外基质受体互作通路（如Col1a1/Sv2c信号通路）密切相关。本研究结果提示，促炎症因子介导的自噬调控可能成为逆转心肌肥厚和预防心衰的新靶点。