环氧二十碳-三稀酸通过Smad7抗心房纤维化/房颤的机制研究

Atrial fibrosis is considered as a key factor leading to ineffective treatment of atrial fibrillation. Recent studies suggest that Smad7 may be a new target for the treatment of atrial fibrosis/atrial fibrillation. EETs(epoxyeicosatrienoic acids) is a kind of small molecules derived from arachidonic acid metabolism via cytochrome P450 epoxygenase, with anti-myocardial fibrosis and potential anti-arrhythmic effects. Our preliminary experiments found that EETs inhibited atrial fibroblast transdifferentiation and collagen secretion, this effect may be achieved through Smad7. Therefore, we hypothesized that EETs may inhibit atrial fibrosis/atrial fibrillation, a mechanism involving Smad7 signaling pathway. In view of this, by use of molecular biology techniques and electrophysiological techniques, the present study will confirm that EETs inhibit fibroblast activation via regulation of Smad7 pathway; that transfected exogenous cytochrome P450 epoxygenase gene can suppress atrial fibrosis in a canine model of atrial fibrillation,and reduce incidence and persistence of atrial fibrillation. This project will elucidate protective effects and mechanisms of EETs on atrial fibrosis/atrial fibrillation, which will lay the foundation for drug treatment and gene therapy of atrial fibrillation.

目前多认为心房纤维化是导致房颤治疗效果不佳的关键因素。最近研究提示Smad7可能是治疗心房纤维化/房颤的新靶点。环氧二十碳-三烯酸(EETs，epoxyeicosatrienoic acids)是花生四烯酸经细胞色素P450表氧化酶代谢产生的一种小分子物质，具有抗心肌纤维化和潜在的抗心律失常作用。我们预实验发现EETs可抑制心房成纤维细胞转分化及胶原分泌，这一效应可能是通过Smad7实现的。因此，我们推测EETs具有抗心房纤维化/房颤的作用，其机制涉及Smad7相关信号通路。鉴于此，本课题拟采用分子生物学技术和电生理技术，在心房成纤维细胞中证实EETs通过调控Smad7通路，抑制成纤维细胞激活；在房颤犬模型上证实转染外源细胞色素P450表氧化酶基因能抑制心房纤维化，减少房颤发生和持续。本课题将阐明EETs能否在心房纤维化/房颤中起保护作用及相关机制，为房颤的药物和基因治疗奠定基础。

心房纤维化是导致房颤治疗效果不佳的关键因素。环氧二十碳-三烯酸(EETs ， epoxyeicosatrienoic acids)是花生四烯酸经细胞色素P450 表氧化酶代谢产生的一种小分子物质，具有抗心肌纤维化和潜在的抗心律失常作用。Smad7是抗心房纤维化/房颤的重要靶点。首先，在心房成纤维细胞，EETs通过PPARγ途径促发抗纤维化分子Smad7发生核转位。进而，研究发现EETs抑制Ang II诱导的心房成纤维细胞转分化（α-SMA染色）和胶原合成（Col-1A1/3A1），其作用被PPARγ抑制剂和Smad7 SiRNA阻断。此外，研究发现EET上调了抗心脏纤维化相关Micro-RNA（miR-29b、miR-133, miR-30 和 miR-590）表达水平，但是miR-29b是被EET上调最高的Mico-RNA。而且，EET的抗纤维化作用被miR-29b拮抗剂几乎完全阻断。最后，我们在血管紧张素 II(Ang II)诱导的心房纤维化模型中，研究发现CYP表氧化酶基因2J2(CYP-2J2) 通过激活Smad7/miR-29b显著抑制心房纤维化，并减少房颤发生率。以上结果提示CYP 表氧化酶基因/EETs通过PPARγ激活抗纤维化分子Smad7/miR-29b，进而抑制心房纤维化，预防房颤的可能机制。为未来房颤的药物和基因治疗奠定基础。