Interferon-gamma inhibits 35S incorporation in heparan sulfate synthesized by human skin fibroblasts.

Glycosaminoglycans synthesized by human skin fibroblasts were simultaneously radiolabelled with D-[1-(3H)]glucosamine and Na2(35)SO4. Considering 3H incorporation, we found that IFNgamma increased the production of glycosaminoglycan synthesis, including hyaluronic acid, heparan and chondroitin/dermatan sulfate. In contrast, the production of heparan and chondroitin/dermatan sulfate was slightly decreased on the basis of the 35S signal. Furthermore, when heparan sulfate was treated with nitrous acid, the release of free 35S was greater in control than in treated cells, although the 3H patterns of depolymerization with this agent were similar. These data demonstrate that IFNgamma inhibits the incorporation of sulfate from extracellular medium into heparan sulfate.

Interferon gamma differentially affects the synthesis of chondroitin/dermatan sulphate and heparan sulphate by human skin fibroblasts.

Interferon gamma (IFN gamma) is often considered to be an antifibrotic cytokine because it inhibits collagen synthesis in fibroblasts. Here we report the effects of recombinant human IFN gamma on sulphated glycosaminoglycan chains produced by normal skin fibroblasts from adult donors. IFN gamma (250 i.u./ml) induced an increase in incorporation of D-[1-3H]glucosamine into glycosaminoglycans, either secreted into the culture medium or associated with the cell layer. The structures of these molecules were analysed by using various cleavage agents (heparinases I and II, heparitinase/chondroitinases ABC and AC/periodate oxidation) followed by size-exclusion and anion-exchange HPLC. No modification was detected in the structure of the heparan sulphate chains. In contrast, the cytokine induced changes in the microcomposition of chondroitin/dermatan sulphate chains. More precisely, we found a decrease in the iduronic acid content, associated with down-regulation of the 4-O-sulphation on the GalNAc residues. In contrast, the 6-O-sulphation on these GalNAc residues was potentiated by the cytokine. These results indicate that IFN gamma is able to modulate not only collagen but also the structure of galactosaminoglycans synthesized by human skin fibroblasts.

Distribution of hepatic glycosaminoglycans during acute schistosomiasis: modulation by IFN gamma treatment.

An important pathological outcome of schistosomiasis is hepatic fibrosis, with a significant deposit of collagens and proteoglycans. In this study, hepatic and granuloma-associated glycosaminoglycans (GAGs) were analyzed both quantitatively and qualitatively at the acute stage of murine infection with Schistosoma mansoni. The effects of IFN gamma, which has been successfully used for reducing collagen deposition in the liver during schistosomiasis, were also analyzed in granulomas and the surrounding liver parenchyma. Acute schistosomiasis resulted in a 4.4-fold increase in total hepatic GAG content, from which granulomatous GAGs--mainly chondroitin sulfates A/C and B--represented only one sixth of total GAGs amount. Therefore, the increase was found predominantly in the parenchyma. In this compartment, qualitative changes were also induced with a marked increase in the proportion of chondroitin sulfates A/C balanced by a decrease in the proportion of heparan sulfate and dermatan sulfate. IFN gamma reduced parenchymal GAG content by 47%. Qualitatively, the cytokine increased the proportion of heparan sulfate and reduced the quantity of chondroitin sulfates A/C by half in this compartment. By contrast, IFN gamma had neither quantitative nor qualitative effect on fibroinflammatory granulomas. In these structures, the absence of heparan sulfate--which is suspected to mediate IFN gamma activity--might explain these observations.