Transient exposure to inflammation-associated, fibroblast-stimulatory factors appears to initiate fibrosis by inducing the persistently activated phenotypes displayed by fibroblast cultures derived from scleroderma skin and other fibrotic tissues. To determine whether one class of fibroblast-inhibitory factors, the interferons (IFNs), plays a role in terminating fibrosis by acting as persistent fibroblast deactivators, we inhibited (40-60%) the growth and collagen production of normal dermal fibroblasts and hypercollagen-producing scleroderma fibroblasts by short-term exposure to IFN-alpha, beta, or gamma. During subsequent subculture in the absence of IFNs, the growth and collagen production of normal fibroblasts and the growth of scleroderma fibroblasts increased to untreated control levels after two to three passages. In contrast, collagen production by scleroderma fibroblasts remained inhibited for at least five passages (18 cell doublings) and was not further suppressed by subsequent IFN exposure. These data suggest that IFNs may help terminate fibrosis by suppressing persistently activated fibroblast functions.
M R Duncan, B Berman