Effect Of Spironolactone On Matrix Metalloproteinases And Tissue Inhibitors Of Metalloproteinases Post Myocardial Infarction

Background Left ventricular remodeling after acute myocardial infarction (AMI) results in impaired function and at last heart failure. It refers to alterations in ventricular mass, chamber size, and shape.The mechanism of remodeling is not very clear, mainly include anormal neuroendocrine regulation, cytokine activation and gene expression, caused a series of pathological changes.Among them, the ventricular remodeling of extracellular collagen matrix remodeling plays a very important role. RALES and EPHESUS showed that the addition of an aldosterone blocker to the optimal medical therapy reduced morbidity and mortality among patients with AMI complicated by left ventricular dysfunction and heart failure. Both clinical tries showed that the block of aldosterone was benefit for the host. Qi Dong and others confirmed treated patients with acute anterior myocardial infarction with a small dose of spironolactone based on the conventional treatment, could further inhibit the left ventricular expansion and fibrosis, and to prevent the occurrence of ventricular remodeling. Nicoletti and others verified that spironolactone can inhibit collagen protein synthesis obviously. Shimin Dong and others confirmed that Spironolactone could reduce serum collagen metabolism in patients with acute myocardial infarction, inhibited left ventricular remodeling and improve cardiac function.Through animal experiments they found that spironolactone and Losartan treatment could significantly reduce non-infarcted myocardium collagen deposition and I/III-type collagen ratio, inhibited collagen proliferation.MMPs is a family of enzyme which can degrade collagen, plays an important role in many tissues, especially in myocard tissue. It has been proved that MMPs high expressed in hypertensive disease , artherosclerosis and ACS. Tissue inhibitors of metalloproteinases (TIMPs) is the most important endogenous inhibitors of MMPs. Proved by experiment, ventricle remodeling process started when the dynamic balance of MMPs and TIMPs was destroied after myocardial infarction. Kaden found that, MMP-9 concentration increased early in the patient with AMI and 1 week later back to the baseline, TIMP-1 increased slowly, 6 month later back to the baselinel. Hayashidani founed that, left venticular rupture incidence decreased in the mouse with MMP-2 gene knockout after left coronary artery ligated. In additional, other studies also showed that MMPs promoted ventricle remodeling process post MI. Rude MK found that aldosterone from extrinsic source enhanced the activity of MMP-2 and MMP-9. Other studies indicated that spironolactone inhibited vascular remodeling by inhibiting MMPs. Howerer, there was no evidence showed that if aldosterone antagonists have some effects on MMPs and TIMPs in the process of remolding post myocardial infarction.Objctive Investigate the effects of the aldosterone receptor antagonism spironolactone on the relationship between MMPs/TIMPs expression and LV remodeling after myocardial infraction, to explore the molecular mechanism for the prevention of heart failure after myocardial infarction, and provide a theoretical basis and new ideas.Methods: We established the left ventricular infarct in rats by ligation of the left anterior descending coronary artery. 90 healthy male Sprague Dawley rats (12-15 weeks and 210-260g) in this study were divided into Sham group (water, 2ml·d-1 in drinking, 6), AMI group (water, 2ml·d-1 in drinking, 6) and Spironolactone group (Spi, spironolactone 20mg·kg-1·d-1,6). Histopathology was detected by HE staining. Infarct size and left ventricular dilated index was calculated. RT-PCR was used to observe the gene expression of MMP-2mRNA,TIMP-2mRNA in the noninfarcted zone. The MMP-2 and TIMP-2 protain was quantified by immunohistochemical method. All data were analyzed with SPSS version 11.5 statistical software. The comparison among groups was analyzed by One-Way ANOVA and S-N-K test. The relationshiop between MMP-2mRNA and left ventricular dilated index was analyzed by linear correlation and regression.Results The left ventricular dilated index was increased significantly in the AMI group and Spi group in 7d,14d and 21d (all P<0.01). In comparison with AMI group,the left ventricular dilated index significantly decreased by 8%(P<0.05), 13%(P<0.05) and 16%(P<0.01) respectively at 7d,14d and 21d in Spi group, but there were no significant difference at 48h. (P>0.05).In comparison with Sham group,MMP-2 was increased significantly in the AMI group and Spi group at 48h, in 14d reached peak, and in 21d maintained in a high level (all P<0.01). In comparison with AMI group, MMP-2 significantly decreased by 17%,27% and 29%(allP<0.01) respectively at 7d,14d and 21d in Spi group, but there were no significant difference at 48h. (P>0.05).In comparison with Sham group,TIMP-2 was increased gradually in the AMI group and Spi group, in 14d reached peak, and in 21d maintained in a high level (all P<0.01). In comparison with AMI group, TIMP-2 significantly decreased by 14%(P<0.05),27% and 29%(P<0.01) respectively at 7d,14d and 21d in Spi group, but there were no significant difference at 48h. (P>0.05).Compared with Sham group, MMP-2mRNA was increased significantly in the AMI group and Spi group at 48h, in 14d reached peak, and in 21d maintained in a high level (all P<0.01).In comparison with AMI group, MMP-2mRNA significantly decreased by 30%,33% and 43%(allP<0.01) respectively at 7d,14d and 21d in Spi group, but there were no significant difference at 48h. (P>0.05).In comparison with Sham group, TIMP-2mRNA was increased significantly in the AMI group and Spi group at 48h, in 7d reached peak, in14d and 21d maintained in a high level (all P<0.01).In comparison with AMI group, TIMP-2mRNA significantly decreased by 14%(P<0.05),25% and 34%(P<0.01) respectively at 7d,14d and 21d in Spi group, but there were no significant difference at 48h. (P>0.05).In AMI group, the relationship between MMP-2mRNA and left ventricular dilated index 14d post AMI was that MMP-2mRNA correlated positively with left ventricular dilated index. The regression equation was Y=-0.14+0.16X,r=0.90(P<0.05)。Conclusion MMP-2 and TIMP-2 were increased significantly post AMI. And the MMP-2mRNA correlated positively with left ventricular dilated index.The use of Spirolactone in AMI caused a reduction of MMPs and TIMPs both in the levels of transcription and expression. By regulating the MMPs/TIMPs, spirolactone prevented LV remodeling.