To obtain a dynamic and non-invasive picture of hepatic
fibrosis in pre-cirrhotic
liver diseases we measured both the concentration of the N-terminal
peptide of
procollagen III, as a marker of
collagen synthesis, and the activity of
PZ-peptidase, an
enzyme involved in
collagen degradation, in the serum of alcoholic or chronic viral
hepatitis patients.
Peptide serum levels were similar in
chronic persistent hepatitis and controls, but significantly higher in
chronic active hepatitis.
Chronic persistent hepatitis patients had
PZ-peptidase levels higher than controls, but similar to
chronic active hepatitis. The increase in
collagen synthesis without a parallel increase in
collagen degradation seen in
chronic active hepatitis could be regarded as a sign of impending
cirrhosis, whereas the unbalanced rise in
PZ-peptidase observed in
chronic persistent hepatitis is consistent with the non-progressive character of this disorder. In
alcoholic hepatitis both
peptide concentration and
PZ-peptidase activity were elevated, thus suggesting that both
collagen synthesis and degradation are activated. However, the greater increase in
PZ-peptidase than in
peptide serum levels seen in some patients seems to indicate a minor tendency to progressive
fibrosis or a trend towards resolution. Unlike
liver disease patients, normal
peptide and
PZ-peptidase levels were found in patients with pancreatic
fibrosis. Since circulating inhibitors and activators of the
PZ-peptidase activity can be excluded, as proved by this study, joint
peptide and
PZ-peptidase serum measurements would seem to offer a simple reliable non-invasive method for differentiating and monitoring progressive and non-progressive forms of hepatic
fibrosis.