title: [Expression of matrix metalloproteinase-9 in myocardium of mice with viral myocarditis].
abstract: OBJECTIVE
  To investigate the dynamic changes of expression of matrix metalloproteinases-9 in myocardium of mice with viral myocarditis (VMC) and its significance in the pathogenesis of viral myocarditis.
  
  
  METHODS
  VMC model was prepared by an injection of CVB3 in BALB/C mice. The mice receiving an injection of culture solution without virus were used as the control group. Cardiac tissues were obtained 7, 14, 21 and 28 days after injection and made into paraffin sections. Myocardial histopathologic changes were observed by hematoxylin-eosin staining and Masson staining. The expression of MMP-9, type I collagen and type III collagen in cardiac tissues were quantified by SABC immunohistochemical method.
  
  
  RESULTS
  The expression of MMP-9 in the VMC model group was observed on the 7th day, reached a peak on the 14th day, and was significantly higher than that in the control group at all time points (P<0.05). Compared with the control group, the expression of type I collagen in the VMC model group was up-regulated on the 21st day and reached a peak on the 28th day (P<0.05). The expression of type III collagen in the VMC model group was significantly higher than that in the control group on the 28th day (P<0.05). The expression of MMP-9 was positively correlated with myocardial histopathologic scores (r=0.832, P<0.05) and negatively correlated with type I collagen expression (r=-0.791, P<0.05).
  
  
  CONCLUSIONS
  MMP-9 is over-expressed at the early stage in VMC mice, and participates in the pathological process of VMC through mediating the degradation metabolism of type I collagen. It may be an important factor that leads to myocardial collagen remodeling and myocardial fibrosis.
authors.affiliation: Department of Pediatrics, Central South University, Changsha, China.
authors.forename: Min
authors.initials: M
authors.lastname: Yang
authors.forename: Chun-Yuan
authors.initials: CY
authors.lastname: Chen
authors.forename: Zi-Li
authors.initials: ZL
authors.lastname: Cai
authors.forename: Bo-Lin
authors.initials: BL
authors.lastname: Chen
authors.forename: Liang
authors.initials: L
authors.lastname: Cheng
authors.forename: Hui
authors.initials: H
authors.lastname: Li
mesh_terms: D000818:Animals; D024042:Collagen Type I / Q000032:analysis; D024061:Collagen Type III / Q000032:analysis; D003384:Coxsackievirus Infections / Q000201:enzymology*; D029822:Enterovirus B, Human; D007150:Immunohistochemistry; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000032:analysis*; D051379:Mice; D008807:Mice, Inbred BALB C; D009205:Myocarditis / Q000201:enzymology* / Q000473:pathology; D009206:Myocardium / Q000201:enzymology* / Q000473:pathology
chemical_list: D024042:Collagen Type I; D024061:Collagen Type III; D020780:Matrix Metalloproteinase 9