血管紧张素Ⅱ-1型受体自身抗体通过激活心肌成纤维细胞参与心肌纤维化

Angiotensin Ⅱ type 1 receptor autoantibody induces myocardial fibrosis by activating cardiac fibroblasts

心肌纤维化(myocardial fibrosis,MF)是造成心衰患者心脏重构的重要病理过程,但其病因并不完全清楚。已知血管紧张素II-1型受体自身抗体(angiotensin II type 1 receptor autoantibody,AT1-AA)存在于心衰患者体内,但该抗体能否直接导致MF尚不明确。本文旨在探讨AT1-AA致MF的作用及其对心肌成纤维细胞(cardiac fibroblasts,CFs)的影响。通过主动免疫法建立AT1-AA阳性大鼠模型,于主动免疫8周时检测各指标,小动物心脏超声结果显示,AT1-AA阳性组大鼠心脏舒缩功能下降,心腔扩大、室壁变薄;HE染色结果显示,AT1-AA阳性组大鼠心肌纤维走向紊乱,有断裂现象;Masson染色结果显示,AT1-AA阳性组大鼠心肌间质和血管周围的胶原纤维沉积明显增多(P<0.05);血压测量结果显示,AT1-AA不会引起大鼠的血压和心率变化。AT1-AA作用于分离培养的原代乳鼠CFs 48 h后,用CCK-8法和免疫荧光法检测CFs增殖情况,结果显示,AT1-AA可显著促进CFs增殖(P<0.001);Western blot结果显示AT1-AA显著促进CFs中胶原蛋白I(collagen I,Col I)、Col III、基质金属蛋白酶-2(matrix metalloproteinase-2,MMP-2)和MMP-9的表达(P<0.05)。以上结果提示,AT1-AA可能通过激活大鼠CFs导致MF,进而导致心功能下降。

Myocardial fibrosis （MF） is an important pathological process of cardiac remodeling in patients with heart failure; however its etiology has not been clear. It has been known that the angiotensin II type 1 receptor autoantibody （AT1-AA） is present in patients with heart failure, but it is unclear whether this antibody directly causes MF. In this study, we investigated the role of AT1-AA in MF and its effects on cardiac fibroblasts （CFs）. The AT1-AA positive rat model was established by active immunization method, and the measurement of indexes were made in the 8th week after active immunity. The results of heart echocardiography showed that the cardiac systolic and diastolic functions of AT1-AA positive rats were impaired with reduced left ventricular wall thickness and enlarged heart chambers. HE staining results showed that the myocardial fibers were disorganized and ruptured, and Masson staining revealed that the area of collagen fibers around the myocardium and coronary arteries was significantly increased in AT1-AA positive group compared with that of the control group （P 〈 0.05）. Moreover, primary CFs isolated from neonatal rats were cultured and treated with AT1-AA for 48 h. CCK-8 and immunofluorescence staining results showed that AT1-AA enhanced proliferation rate of CFs （P 〈0.001）, and Westem blot results showed that AT 1-AA significantly increased expressions of collagen I （Col I）, Col III, matrix metallo- proteinase-2 （MMP-2） and MMP-9 in CFs （all P 〈 0.05）. Taken together, these results suggest that AT1-AA may induce MF and cardiac dysfunction via activating CFs.