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AIM: Matrix metalloproteinase-1 (MMP-1) and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) are central to the spontaneous resolution of liver fibrosis. The mechanisms involved have been investigated in hepatic steilate cells (ISC), but not in hepatocytes. We investigated the effects of fibril- and fixed-collagen on MMP-1 and TIMP-1 production in hepatocytes, using the HLE cell line.METHODS: Fibril type T and Ⅳ collagen were prepared by HCl digestion of type T and Ⅳ collagen, respectively.For fixed-collagen, culture dishes were coated with fibril type Ⅰ or Ⅳ collagen and fixed by ultraviolet. Type Ⅰcollagenase activity was measured using fluorescein isothiocyanate-labeled type Ⅰ collagen. MMP-1 and TIMP-1 in HLE cells were measured by a one-step sandwich enzyme immunoassay.RESULTS: Both fibril type Ⅰand Ⅳ collagen significantly increased type Ⅰ coilagenase activity about two-fold compared with no fibril collagen. The effects of the fibril collagen were not affected by the coating condition. There was no significant difference in the effects on collagenase activity between cells cultured in medium containing fibril type Ⅰ collagen and those cultured in the presence of type Ⅳ collagen. Both types of fibril collagen significantly increased MMP-1 production, and showed more than 10-fold higher levels of MMP-1 than the control. The enhanced MMP-1 production by fibril collagens was unaffected by the coating condition. By contrast, TIMP-1 production was not changed by the addition of fibril type Ⅰ or Ⅳ collagen,and neither was it affected by the coating conditions.Coating with type Ⅰ collagen significantly suppressed MMP-1production by almost one-tenth compared with no coating.By contrast, lIMP-1 production was not affected by either the absence of a collagen coat or by increasing the concentration of the coating collagen.CONCLUSION: These results indicated that, in HLE cells,fibril- and fixed-collagen have opposite effects on MMP-1production without affecting TIMP production. Fibril collagen induced collagenase activity by up-regulation of MMP-1 production without affecting TIMP-1 production.By contrast, fixed collagen reduced MMP-1 production.Our results suggest that hepatocytes might also play an important role in the regulation of the hepatic fibrosis alongside HSC.