Drug-induced glycosaminoglycan storage: Dose-dependent changes in the pattern of accumulated glycosaminoglycans in cultured bovine and human fibroblasts

Abstract

The present study determines the amounts and patterns of glycosaminoglycans stored in cultured corneal fibroblasts after treatment with tilorone and three related compounds. The compounds have immunomodulatory properties and have been shown to impair the lysosomal degradation of glycosaminoglycans as a side effect. This side effect has been described as drug-induced mucopolysaccharidosis because the induced lysosomal storage of glycosaminoglycans leads to cellular lesions resembling those in patients with inherited mucopolysaccharidosis. In the present study, the dose-dependency of glycosaminoglycan storage was analyzed after treatment (96 hr) of bovine corneal fibroblasts. The investigated drug concentrations ranged from low concentrations inducing cytological lesions typical of drug-induced mucopolysaccharidosis to high concentrations at the borderline of cytotoxicity. The intracellular amounts of dermatan sulfate, heparan sulfate, and chondroitin sulfate were quantified by densitometric scanning of Alcian Blue-stained bands after electrophoresis. All investigated compounds induced a predominant dermatan sulfate storage (3–4-fold accumulation) at low drug concentrations. With rising drug concentrations, a shift of the pattern of stored glycosaminoglycans was observed, characterized by the additional accumulation of heparan sulfate (up to 5-fold of control levels). In cultured human fibroblasts, tilorone also caused a marked dermatan sulfate storage, reaching maximum values at 5 μM and marked heparan sulfate storage at 20 μM. The present data provide evidence: (a) that selective dermatan sulfate accumulation is a characteristic feature of drug-induced glycosaminoglycan storage in cultured bovine and human fibroblasts, if these cells are treated with low concentrations (⩽ 5 μM), that are likely to reflect the situation in vivo; and (b) that additional heparan sulfate storage is induced in vitro only by treatment with high concentrations that induce nonspecific cellular lesions.