腺苷/腺苷A2A受体在松弛素抑制心脏纤维化中的作用及机制研究

Relaxin belongs to the insulin superfamily, in recent years found by cardiac autocrine, involved in the physiology and pathology regulation of diseases as heart failure and other diseases ,which has been reported to be prevent or reverse cardiac fibrosis .It is expected to become a new drug against cardiac fibrosis ,however,the exact action mechanism remains unclear. Heart is one of the organs that have the most exuberant of energy metabolism in the organism. And relaxin structurally belongs to the insulin superfamily that might participate in energy metabolism. Moreover, our previous experiment showed that the administration of relaxin resulted in an increase of adenosine in plasma and myocardial tissue，an increase of the expression of adenosine A2A receptors in myocardial tissue in mice. According to this, we make a hypothesis that relaxin participants in inhibition of cardiac fibrosis through impacting adenosine/adenosine A2A receptors. This project intends to observe the effects of relaxin on adenosine intake,adenosine precursor content,adenosine-generating and -scavenging key enzymes in an isoprenaline –induced myocardial fibrosis mouse model and in TGF-beta-treated cardiac fibroblasts and myocardial cell; investigate the possible pathophysiological effect of the anti-fibrosis effect of relaxin in adenosine A2A receptor knockout mice; further investigate the peroxisome proliferators-activated receptor γ going into depth on the molecular mechanisms of relaxin of regulating the expression of adenosine A2A receptors. Through the above researches, we preliminary explore the regulating mechanism of energy metabolism of relaxin in inhibiting of cardiac fibrosis.

松弛素属于胰岛素超家族，近年来发现可由心脏自分泌，参与心衰等疾病的病理生理调节,可以防止或逆转心脏纤维化,有望成为抗心脏纤维化治疗的新型药物，但其病理生理机制仍不明确。心脏是机体能量代谢最旺盛器官之一，而松弛素结构上属于胰岛素超家族可能参与细胞能量调节，我们发现松弛素治疗后小鼠血浆、心肌腺苷水平增加、心脏腺苷A2A受体表达增高，据此我们提出松弛素可能通过影响腺苷/腺苷A2A受体参与抑制心肌纤维化。本项目拟在异丙肾诱导的小鼠心肌纤维化模型以及TGF-beta刺激的心肌成纤维细胞和心肌细胞模型上，观察松弛素对腺苷摄取、腺苷前体含量、腺苷产生及清除关键酶的影响；利用腺苷A2A受体敲除小鼠探讨松弛素抑制纤维化可能的病理生理作用；并进一步以过氧化物酶增殖物激活受体γ为靶点，深入探讨松弛素调控腺苷A2A受体表达的分子机制。通过以上研究内容，初步探讨松弛素抑制心肌纤维化的能量调节机制。

心肾综合征的机制复杂，目前尚未完全了解，而纤维化可能是该疾病病理生理学的主要因素。松弛素（RLX）和螺内酯（SP）均可通过抑制内皮间质转化（EndMT）来减少心脏或肾脏纤维化。这种保护作用可能依赖于腺苷受体的激活，但腺苷A2A受体（A2AR）的作用尚不清楚。本项目探讨了松弛素和A2AR在心脏纤维化及EndMT中的作用，发现螺内酯可能通过调节A2AR来抑制EndMT和减少心肾重构。在通过皮下注射异丙肾上腺素（Iso）建立大鼠肾损伤合并心力衰竭模型中，我们检测了心脏和肾脏功能、纤维化、EndMT标记、腺苷和A2AR的表达水平。TGF-β被用来诱导人类脐静脉内皮细胞(HUVECs)产生EndMT现象。大鼠或细胞被随机分为4组：模型组，模型组单独使用螺内酯治疗，模型组联合使用螺内酯和A2AR拮抗剂ZM241385（ZM）共同治疗，正常对照组作为参照。我们发现异丙肾上腺素处理的大鼠表现出心脏和肾脏纤维化，心脏和肾功能受损，EndMT增强，A2AR表达降低。螺内酯治疗后可显著上调A2AR的表达，抑制EndMT的表达。此外，螺内酯治疗后改善心肾重构及其功能障碍。ZM241385可以取消螺内酯处理后引起的改变。总之，以上结果表明，螺内酯通过上调A2AR减少EndMT和改善心肾纤维化。螺内酯的抗纤维化作用可能部分依赖于A2AR的上调，这说明A2AR可能是治疗心肾综合征的潜在治疗靶点。该项目资助发表SCI文章9篇，培养硕士生9名，其中4名已取得硕士学位，5名在读。