| Summary: | <p>Abstract</p> <p>Background</p> <p>Tissue inhibitor of metalloproteinase 1 (TIMP-1), which is thought to be produced mainly by activated hepatic stellate cells and Kupffer cells in the liver, plays a pivotal role in matrix remodeling during liver injury and repair; while the effect of TIMP-1 on hepatocellular damage remains obscure.</p> <p>Results</p> <p>Hepatic expression of TIMP-1 mRNA and protein was up-regulated both in acute and chronic liver injury induced by carbon tetrachloride (CCl<sub>4</sub>). Compared with wild-type mice, TIMP-1 knockout mice were more susceptible to CCl<sub>4</sub>-induced acute and chronic liver injury, as shown by higher levels of serum alanine aminotransferase (ALT), greater number of apoptotic hepatocytes, and more extended necroinflammatory foci. TIMP-1 knockout mice also displayed greater degree of liver fibrosis after chronic CCl<sub>4 </sub>injection when compared with wild-type mice. <it>In vitro </it>treatment with TIMP-1 inhibited cycloheximide-induced cell death of primary mouse hepatocytes. Finally, up-regulation of TIMP-1 in the liver and serum after chronic CCl<sub>4 </sub>treatment was markedly diminished in hepatocyte-specific signal transducer and activator of transcription 3 (STAT3) knockout mice. <it>In vitro </it>treatment with interleukin-6 stimulated TIMP-1 production in primary mouse hepatocytes, but to a lesser extent in STAT3-deficient hepatocytes.</p> <p>Conclusions</p> <p>TIMP-1 plays an important role in protecting against acute and chronic liver injury and subsequently inhibiting liver fibrosis induced by CCl<sub>4</sub>. In addition to activated stellate cells and Kupffer cells, hepatocytes are also responsible for TIMP-1 production during liver injury via a STAT3-dependent manner.</p>
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