Study On Mechanisms Responsible For Myocardial Fibrosis In Viral Heart Diseases And Its Pharmaceutical Intervention

Myocardial fibrosis is fibrous tissue accumulation or collagen contents alterationin normal heart tissue, and is the characteristic pathological change in viral heartdiseases including acute and chronic myocarditis and partial dilated cardiomyopathy(DCM). Excess cardiac fibrosis is a major determinant that contributes to theprogression of arrhythmia, heart failure and cardiac sudden death in viral heartdiseases, and the development from myocarditis to cardiomyopathy. However,mechanisms of which are not well addressed. The present study was carried out toinvestigate the mechanisms responsible for myocardial fibrosis in different phase ofviral heart diseases and seek for effective pharmaceutical intervention. The wholestudy included four parts as follows: Part I: Establishment of Animal Models of Viral Heart Diseases[Objective] To establish animal models of acute and chronic myocarditis anddilated cardiomyopathy.[Methods] One hundred and twenty Balb/c mice were randomized to 3 groups,they were groups of day7 (n=30), month 3 (n=40) and month 9 (n=50),respectively.Ten mice selected randomly from each group were injected ip with Eagle's minimalessential medium (EMEM) solution, and served as controls; the remaining of themwere inoculated ip with coxsackievirus B3(CVB3) diluted in EMEM solution toestablish animal model of acute and chronic myocarditis and DCM. Mice from eachgroup (controls and models) were examined by echocardiography on day7, mon3 andmon9 postinoculation,respectively and then were sacrificed. Portions of heart wereprocessed for histological and morphological examination,blood samples wereobtained to conduct subsequent biochemical analysis.[Results] Degeneration and necrosis of cardiomyocyte, inflammatory infiltrationwere seen in hearts of CVB3-infected mice on day 7; less inflammatory infiltrationand marked interstitial fibrosis were seen in infected mice on mon3, left ventricular(LV) systolic function was found decreased in comparison with controls;noinflammatory infiltration but diffused fibrosis was seen on mon9, LV dilation anddysfunction were verified by echocardiography. 5 复旦大学博士论文. 2004病毒性心脏病心肌纤维化的发生机制及其药物干预研究 英文摘要[Conclusions] Animal models of acute and chronic myocarditis and DCM weresuccessfully established in Balb/c mice infected with CVB3.Keywords: Myocarditis; cardiomyopathy, dilated; coxsackievirus B; modelPart II:Study on Mechanisms Responsible for Myocardial Fibrosis in Viral Heart Diseases[Objective] To investigate mechanisms responsible for myocardial fibrosis in viralheart diseases.[Methods] The collagen specific picrosirius red staining was performed in slides ofheart samples from controls and mice of each phase of viral heart diseases, then thecollagen volume fraction (CVF) was calculated. The serum concentrations ofaminoterminal propeptide of type III procollagen (PIIINP), aminoterminal propeptideof type I procollagen (PINP) and carboxyterminal propeptide of type I procollagen(PICP) in each group were detected by enzyme linked immunosorbent assay (ELISA).Expression of profibrotic cytokines (transforming growth factor 1, TGFβ1, andplatelet derived growth factor BB, PDGF-BB), collagenases and the tissue inhibitor(matrix metalloproteinase 1 and tissue inhibitor of metalloproteinase1,MMP-1/TIMP-1; MMP13 and MMP14), aldosterone synthase(CYBIIB2) and 11β-hydroxysteroid dehydrogenase(11β-HSD)was determined by western blot analysis.Expression of extracellular matrix genes in heart of mice was detected by cDNAmicroarray analysis and confirmed by subsequent reversed transcriptional polymerasechain reaction (RT-PCR). The cardiomyocyte apoptosis in each group of mice wasdetermined by terminal deoxynucleotidyltransferase -mediated dUTP-biotin nickend-labeling (TUNEL) assay, the expression of ap...