Hepatic fibrosis in rats produced by carbon tetrachloride and dimethylnitrosamine: observations suggesting immunoassays of serum for the 7S fragment of type IV collagen are a more sensitive index of liver damage than immunoassays for the NH2-terminal propeptide of type III procollagen.

Liver fibrosis was induced in rats both with carbon tetrachloride and dimethylnitrosamine. Assays were performed on steady-state levels of messenger RNAs in the liver for several collagens and basement membrane components. The results indicated marked increases in the steady-state levels of messenger RNA for type I collagen, type III collagen, type IV collagen and the B2 component of laminin. In the same animals, immunoassays were performed for serum levels of the N-terminal propeptide of type III procollagen and the 7S fragment of type IV collagen. The results demonstrated an increase in the serum levels of 7S fragment that occurred early and closely paralleled the increase in the steady-state levels of messenger RNA for the alpha 1(IV) chain of type IV collagen. In contrast, no significant increase was seen in the serum levels of the N-propeptide of type III procollagen. The results suggest that immunoassays for 7S fragment of type IV collagen in serum are a more sensitive index for liver cell damage and fibrosis than assays for the N-propeptide of type III procollagen. The results suggest that greater attention should be paid to assays of 7S fragments in assessing hepatic fibrosis in man.