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[Dynamic evolution of MMP-2 gene expression and its enzymatic activities in experimental liver fibrosis]
Yue-ke Zhu1, Bao-en Wang, Feng-jun Shen
1Artificial Liver Center, Beijing Friendship Hospital, Capital University of Medical Sciences, Beijing 100054, China. zhuyk168@yahoo.com
Objectives:
To explore the dynamic changes and interactions between MMP-2 and TIMP-2 during experimental liver fibrosis.
Methods:
Wistar rats were randomly allocated into a normal group and a model group. To induce liver fibrosis, rats were injected intraperitoneally with dimethylnitrosamine (DMN) three consecutive times in the first week, then two consecutive times per week, totally for 6 weeks. In the normal control group, rats were injected with saline by the same method as the model group. Animals were sacrificed 1, 4, 10, 17, 28, 42, 56 days after starting DMN injections. Conventional histological examinations of the livers were performed with hematoxylin and eosin and Masson staining. The fibrosis was classified into 0 to 4 stages. Hydroxyproline content was determined after liver tissues were hydrolyzed in HCl at 160 degree C for 2 hrs and then measured with spectrometry at 560 nm wavelength. mRNA levels of MMP-2 and TIMP-2 were determined by semi-quantitive RT-PCR. Gelatinase activity of MMP-2 was examined by zymography using gelatin substrate.
Results:
In the model group the hepatic MMP-2 mRNA expression started to increase 10 days after DMN administration and remained at a much higher level than in the normal group throughout the study period, while TIMP-2 mRNA expression started to be lower than in the normal group 17 days after DMN administration and reached the lowest level on the 28th day. Then it rapidly rebounded and remained higher than that in the normal group from the 42nd day to the end of the study period. TIMP-2/MMP-2 began to be lower by several days than that of the normal group after DMN administration through the remaining study period. Zymography showed that the enzymatic activities of both latent MMP-2 and active MMP-2 were increased during the process of liver fibrosis.
Conclusion:
In liver fibrosis, MMP-2 expression increases, while TIMP-2 expression relatively decreases. The enzymatic activities of MMP-2 increase as the liver fibrosis develops.
Insights
In liver fibrosis, matrix metalloproteinase-2 (MMP-2) expression and activity increase, while tissue inhibitor of metalloproteinase-2 (TIMP-2) expression initially decreases then rebounds. This imbalance drives fibrosis progression.
Area of Science:
- Biochemistry
- Cell Biology
- Pathology
Context:
- Liver fibrosis is a significant health concern characterized by excessive extracellular matrix deposition.
- Matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) play crucial roles in tissue remodeling and are implicated in fibrotic diseases.
- Understanding the dynamic interplay between MMP-2 and TIMP-2 is essential for elucidating fibrosis pathogenesis.
Purpose:
- To investigate the temporal changes and interactions of MMP-2 and TIMP-2 during the development of experimental liver fibrosis.
- To correlate MMP-2 and TIMP-2 expression and activity with histological and biochemical markers of fibrosis.
Summary:
- Dimethylnitrosamine (DMN) administration induced liver fibrosis in Wistar rats.
- MMP-2 mRNA expression and enzymatic activity increased significantly following DMN administration.
- TIMP-2 mRNA expression initially decreased and subsequently increased during fibrosis development, leading to an altered MMP-2/TIMP-2 ratio.
Impact:
- The findings highlight an imbalance favoring matrix degradation in early fibrosis, with a later shift towards inhibition.
- This study provides insights into the complex regulation of MMP-2 and TIMP-2 in liver fibrosis.
- The results may inform the development of targeted therapies for liver fibrosis by modulating MMP/TIMP activity.
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