Human skin fibroblasts in culture: procollagen synthesis in the presence of sera from normal human subjects and from patients with dermal fibroses.
Various dermal fibrotic conditions, such as progressive systemic sclerosis, localized morphea and familial cutaneous collagenoma, are characterized by excessive deposition of collagen in the skin. In the present study, we examined the possibility that a circulating serum factor(s) is responsible for increased collagen production in these diseases. The effects of human serum on the synthesis of procollagen were examined by incubating normal human dermal fibroblasts with [3H]proline and varying concentrations of dialyzed heat-inactivated serum. The synthesis of procollagen was measured as formation of nondialyzable [3H]hydroxyproline and collagenase-digestible 3H]polypeptides. In the absence of serum little procollagen was formed but the synthesis was markedly stimulated by the addition of normal serum in a concentration-dependent manner. THe ratio of genetically distinct 3H-procollagens of type I and type III, assayed by DEAE-cellulose chromatography and SDS-polyacrylamide gel electrophoresis after limited pepsin proteolysis, was unaffected by the addition of serum. Thus, normal human serum contains a nondialyzable factor(s) which stimulates the synthesis of procollagens type I and type III equally. Sera from 5 patients with progressive systemic sclerosis, 3 with localized scleroderma, and 2 with familial cutaneous collagenoma were also tested. Sera from these patients failed to stimulate 3H-procollagen production more than sera from healthy age-matched controls. Therefore, no increased quantities or qualitatively aberrant factors were shown to be present in the sera of these patients.