Two assays for measuring fibrosis: Reverse transcriptase-polymerase chain reaction of collagen alpha(1) (III) mRNA is an early predictor of subsequent collagen deposition while a novel serum N-terminal procollagen (III) propeptide assay reflects manifest fibrosis in carbon tetrachloride-treated rats

Using a novel quantitative reverse transcriptase-polymerase chain reaction assay, we have determined the amount of specific mRNA for procollagen alpha (1) (III) (PIIIP) in the carbon tetrachloride (CCl4) model of liver fibrosi s in rats. After a single week of CCl4 application, the amount of PIIIP mRN A was increased approximately 10 times over the untreated control group and continued to increase to approximately 30 times after 7 weeks of intoxicat ion. In this model substantial fibrosis was demonstrated by computer-aided morphometry after 5 to 7 weeks of treatment. Using recombinant murine N-ter minal procollagen alpha(1) (III) propeptide (PIIINP), a novel sensitive imm unoassay for the measurement of circulating PIIINP in rodent sera was estab lished. An increase in PIIINP serum levels was observed after 5 to 7 weeks of CCl4 intoxication, Our results suggest PIIIP gene expression is an early marker of tissue fibrosis. Early PIIIP gene expression is correlated with the extent of the subsequent fibrosis. PIIIP mRNA levels increase much earl ier than conventional histological examination or PIIINP levels. PIIINP mea surements with our new serum assay, on the other hand, are a good noninvasi ve marker of manifest fibrosis but are a poor marker of fibrogenesis. (C) 1 999 Academic Press.