Expression of matrix metalloproteinases in spontaneous regression of liverfibrosis

Background/Aims. Spontaneous regression of liver fibrosis would depend on t he degradation of the excessive matrix in the liver. In this study, we trie d to determine the kinetics of the expression of genes for matrix metallopr oteinase-2 and -13. Methodology: Liver fibrosis induced by carbon tetrachloride was resolved af ter withdrawal of this toxin. Histological staining for fibrous septa and d etermination of liver collagen content were used to evaluate the extent of liver fibrosis. Expression in liver of matrix metalloproteinase-2 and -13 w as determined by reverse transcription-polymerase chain reaction. Results: The fibrous septa became thinner andinterrupted and liver fibrosis resolved rapidly within 10 days. Expression of matrix metalloproteinase-2 and -13 was elevated to 2.5- and 8.7-fold, respectively, at peak fibrosis. The former was maintained at 88% similar to 76% and the later dropped rapid ly to 30% similar to 20% in the recovery periods. Conclusions: Resolution o f liver fibrosis began within 10 days but only to 70%. Gene expression kine tics suggested metalloproteinase-13 might play a more important role in the resolution because it surged more markedly at peak fibrosis and returned t o nearly basal levels in the recovery periods in parallel with liver collag en content.