Glycosaminoglycan Synthesis in Bleomycin-lnduced Pulmonary Fibrosis: Biochemistry and Autoradiography 1

Abstract

At 5, 15, and 45 days following induction of interstitial pulmonary fibrosis by intratracheal administration of bleomycin in hamsters, glycosaminoglycan synthesis was measured, using [³⁵S]sulfate. Total labeled sulfate incorporation into lung glycosaminoglycans was maximally increased over that of saline-instilled controls at 5 days (P ≤ 0.05), declined markedly at 15 days, and returned to control values at 45 days. Separation of the various labeled glycosaminoglycans by chondroitinase digestion and chromatography revealed a transient rise from controls (P ≤ 0.05) in the proportion of labeled chondroitin 4-sulfate at 5 days, followed by an increase from controls (P ≤ 0.05) in proportionate labeling of dermatan sulfate at 15 and 45 days postbleomycin. Autoradiography, using [³⁵S]sulfate, performed at 21 days postbleomycin, revealed an increase from controls in film grain formation in areas of interstitial reaction. Grain formation was greatly reduced by pretreatment of the slide sections with hyaluronidase and chondroitinase, demonstrating the specificity of the label for glycosaminoglycans. The results indicate that glycosaminoglycan synthesis is significantly altered from normal in this model of interstitial lung disease and that dermatan sulfate is preferentially synthesized during the fibrotic phase of the lung reaction.