The Research on Role of Integrin-linked Kinase in Pathogenesis of the Mice with Viral Myocarditis and the Therapeutic Efficacy of Tanshinone in Myocardial Fibrosis
|Keywords||ILK viral myocarditis Tanshinone myocardial fibrosis|
Viral myocarditis (VMC) is a common cardiovascular disease in pediatrics. In China, Acute VMC cases have become one of the main causes of sudden unknown death events in teenagers.Usually chronic myocarditis leads to dilated cardiomyopathy (DCM). These demonstrate that VMC has greatly threatened human health. However, the pathogenesis of VMC is not clarified thoroughly and there are no effective therapies against VMC so far.So it has importantly theoretic and practical significance to illuminate the mechanism of VMC.ILK is an intracellular serine/threonine protien kinase that interacts with the cytoplasmic domains ofβ-integrins and numerous cytoskeleton- associated proteins. ILK has been shown to be involved in the regulation of a number of integrin- mediated biology processes that include cell adhesion, cell shape changes, gene expression and ECM deposition.It is believed that the abnormal expression of ILK may be related with the occurrence and development of VMC. In the invasion process of VMC, ILK probably participate in the formation of myocardial fibrosis. As an significant growth factor to cause tissue fibrosis, TGF-β1 can induce myocardial cell to produce multiple of ECM ingredient include FN. ILK as the downstream factor of TGF-β1 may play the same important role in the formation of myocardial fibrosis. At present the investigation of the Chinese herbal medicine to cure myocardial fibrosis on molecular biology level is very few. In this study, we demonstrate that ILK participate in the process of the occurrence and development of VMC, ILK and TGF-β1 may play an important role in the formation of myocardial fibrosis , meanwhile we discuss the therapeutic efficacy of Tanshinone in myocardial fibrosis.In this study we established VMC models through Balb/c mice infected with coxsackievirus B3 (CVB3). The mice were divided into control group(n=30), virus group(n=40)and Tanshinone group(n=40). After virus inoculation until day 7, 14, 28, 56, we used streptavidinperoxidase immunoperoxidase technique (SP) to detect the contents of ILK and TGF-β1, did Masson staining to myocardium collagenous fibers, and determinated the score for myocardial necrosis, the CK-MB level in blood serum and so on in every group. At the same time we analysised the dependablity of the expression of ILK and TGF-β1 in myocardium, the positive area of myocardium collagenous fibrils and the CK-MB level in blood serum in different period after the infection of CVB3. The intention was to provide new rationale and experimental base to investigate of pathogenesis and the biological prevention to VMC.Our research had found that there was little expression of ILK and TGF-β1 in control group. Meanwhile, the positive area in virus group and Tanshinone group were much larger than that in control group(p<0.01). After the intervention of tanshinone, the mice of Tanshinone group, the positive expression of ILK and TGF-β1 was significant lower than the virus group(p<0.05). Linear correlation analysis showed the the expression area of ILK and TGF-β1 is positive correlation remarkably(r=0.991, p<0.01). The 14th day after the infection of CVB3 we can find the mouse in virus group and Tanshinone group the positive area of the Masson staining was obviously increased compared with control group(p<0.01), but there was no statistical significance between these two groups(p>0.05). After the 28th day there was statistical significance between the three groups in Masson staining(p<0.05). It is indicated that after the mice infected by virus, myocardium collagen aggregated gradually, then formed myocardial fibrosis, and Tanshinone could reduce the degree of myocardial fibrosis. There was positive correlation between the expression of ILK and the positive area of Masson staining(r=0.938,p<0.01). It is indicated that ILK may play an important role in the process of myocardial fibrosis. The result of SP showed that ILK was assumed positive even hadro-positive expression in interstitial cell such as fibroblast and smooth muscle cell. It was further proved that ILK participated in the adhesion between cell and ECM, and provided theory base that ILK may be involved in the occurance and development of VMC.Our study suggested that TGF-β1 can up-regulate the expression of ILK, increased expression of ILK could promote the aggregation of Fn, and the effect showed the time- dependence. Thus, we can propose that ILK as the downstream factor of TGF-β1 may play the same important role in the formation of myocardial fibrosis as TGF-β1. Meanwhile our result showed that Tanshinone could probably inhibit the expression of TGF-β1 to influent the expression of ILK, and reduce the inflammatory reaction of muscular tissues, increase the tolerance to the infection of virus in, lessen the pathological changes of myocardial fibrosis. So we can also make the conclusion that Tanshinone can offer some protection to myocardial fibrosis.In summary, our study can provide new method and theory base to cure VMC at molecular level. We may make the inhibition of the expression and function of ILK as a new therapy target. The study also provided the experimental base to sieve the medicine to prevent and cure myocardial fibrosis.