Dynamic changes in the expression of matrix metalloproteinases and their inhibitors,TIMPs,during hepatic fibrosis induced by alcohol in rats

AIM: To determine the dynamic changes in the expression of matrix metalloproteinases (MMPs) and the endogenous tissue inhibitors of MMPs inhibitors (TIMPs) during hepatic fibrosis induced by alcohol.METHODS: Male Sprague-Dawley rats were randomly divided into normal, 4 d, 2 wk, 4 wk, 9 wk and 11 wk groups, and the model rats were fed with a mixture of alcohol by gastric infusion at the designed time, respectively, then decollated and their livers were harvested for the examination of MMP-2, MMP-3, MMP-9, MMP-13, TIMP-1 and TIMP-2 by immunohistochemistry, zymograghy and Western blotting, respectively.RESULTS: Normal rats had moderate expression of MMP-2,which was decreased in the model rats except in the 11 wk group, where MMP-2 expression slightly increased. MMP-3 had the similar changing pattern to MMP-2 despite weaker expression. MMP-9 expression decreased in the 4 d and 2 wk groups, rose in the 4 wk group, decreased again in the 9 wk group and returned to normal levels in the 11 wk group.MMP-13 expression decreased in the 4 d and 2 wk groups,and returned to normal levels in the 4 wk, 9 wk and 11 wk groups. TIMP-1 expression decreased in the 4 d and 2 wk groups, but sharply increased in the 4 wk group and sustained at a high level even after modeling was stopped for 2 wk. In normal rats TIMP-2 expression was strong. However, it decreased as soon as modeling began, and then gradually rose, but remained to a level lower than that in normal rats even after modeling was stopped for 2 wk.CONCLUSION: MMP-2 may not always expresses at a high level during hepatic fibrosis. MMP-13 and MMP-3 are acutely affected by TIMP-1. In this model TIMP-1 is the most powerful factor imposed on capillarization and peri-sinusoidal fibrosis. TIMP-2 is the most effective regulator on the metabolism of type Ⅳ collagen located in the basement of sinus.

Dynamic changes of capillarization and peri-sinusoid fibrosis in alcoholic liver diseases

AIM:To investigate the dynamic changes of capillarization and peri-sinusoid fibrosis in an alcoholic liver disease model induced by a new method.METHODS:Male SD rats were randomly divided into 6 groups,namely normal,4d,2w,4w,9w and 11w groups.The animals were fed with a mixture of alcohol for designated days and then decollated,and their livers were harvested to examine the pathological changes of hepatocytes, hepatic stellate cells,sinusoidal endothelial cells,sinusoid, perisinusoid.The generation of three kinds of extra cellular matrix was also observed.RESULTS:The injury of hepatocytes became severer as modeling going on.Under electronic microscope,fatty vesicles and swollen mitochondria in hepatocytes,activated hepatic stellate cells with fibrils could been seen near or around it.Fenestrae of sinusoidal endothelial cells were decreased or disappeared,sinusoidal basement was formed.Under light microscopy typical peri-sinusoid fibrosis, griddinglike fibrosis, broaden portal areas, hepatocyte's fatty and balloon denaturation,iron sediment,dot necrosis,congregated lymphatic cells and leukocytes were observed.Type I collagen showed an increasing trend as modeling going on,slightly recovered when modeling stopped for 2 weeks. Meanwhile,type IV collagen decreased rapidly when modeling began and recovered after modeling stopped for 2 weeks.Laminin increased as soon as modeling began and did not recover when modeling stopped for 2 weeks.CONCLUSION:The pathological changes of the model were similar to that of human ALD,but mild in degree.It had typical peri-sinusoid fibrosis, however,capillarization seemed to be instable.It may be related with the reduction of type IV collagen in the basement of sinusoid during modeling.