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In this study, we aimed to explore if QSKL could exert an anti-fibrotic effect by attenuating key molecules of RAAS system.
Sprague-Dawley (SD) rats were randomly divided into 4 groups: sham group, model group (left anterior descending coronary artery ligation), positive control group (LAD ligation and treated with fosinopril) and QSKL group (LAD ligation and treated with QSKL). 28 days after surgery, radioimmunoassay was used to detect the renin and angiotensin II level in serum. Sirius red staining were performed to assess the degree of myocardial fibrosis. Transferase-mediated deoxyuridine triphosphate-biotin nick end labeling (TUNEL) staining were performed to observe the degree of myocyte apoptosis. Alpha smooth muscle actin (a-SMA), matrix metalloproteinase 9 (MMP-9) and tissue inhibitor of metalloproteinase 1 (TIMP-1) were assessed by immunohistochemically method. Real-time PCR was used to detect the mRNA expressions of LIMK1, LIMK2, NHE, moesin and cofilin.
At 28 days after surgery, radioimmunoassay showed that renin and angiotensin II level in the model group increased significantly, indicating the activation of RAAS system. Sirius red and TUNEL staining results demonstrated pathological changes of myocyte apoptosis and myocardial fibrosis. Expressions of fibrotic markers, such as a-SMA and MMP9, were elevated while TIMP-1 were downregulated in model group. LIMK1, LIMK2, moesin and cofilin were upregulated in the model group, indicating the downstream activation of RAAS system.
After intervention of QSKL, renin and angiotensin II level in the QSKL group decreased dramatically compared with model group, suggesting the inhibition of RAAS system. Pathological changes detected by Sirius red and TUNEL staining in QSKL group were not as significant as those in model group. Compared with model group, the expressions of a-SMA and MMP9 were decreased while TIMP-1 were upregulated in QSKL group, indicating QSKL can prohibit the fibrotic process. The mRNA expressions of LIMK1, LIMK2, NHE, moesin and cofilin in QSKL group were down regulated compared with model group, which showed the downstream inhibition of key molecules in RAAS system.
QSKL has definite anti-fibrotic effect in inhibiting RAAS system mainly through attenuating the serum renin and angiotensin II, down-regulating myocyte apoptosis and collagen genesis, besides inhibiting the downstream key molecules of RAAS system. These findings provide evidence for anti-fibrotic effect of QSKL and validate the benefit of QSKL in the clinical application for myocardial fibrosis.