Biosynthesis of glycosaminoglycans in peritoneal macrophages from the guinea pig

Abstract

The majority of glycosaminoglycans synthezied in peritoneal macrophages from the guinea pig in vitro were secreted into culture medium. The secreted glycosaminoglycans were reduced in size with alkali treatment, indicating that the glycosaminoglycanas existed in the form of proteoglycans. After the glycosaminoglycans were digested with chondroitinase AC and ABC, the high voltage paper electrophoretic analysis and the descending paper chromatographic analysis indicated the presence of a considerable amount of unsaturated disulfated disaccharides. Based on the enzymatic assay with chondro-4- and 6-sulfatase, the positions of sulfation in the disulfated disaccharide have been identified as the 4- and 6-position of N-acetylgalactosamine, Moreover, the results of the ion-exchange chromatography and the chondroitinase AC and ABC digestion indicate that ΔDi-diS E derived from dermatan sulfate. This suggests that peritoneal macrophages are capable of synthesizing oversulfated proteodermatan sulfate as main component. The proportion of synthesized oversulfated dermatan sulfate to the total glycosaminoglycans was independent of the incubation time, and the distribution of oversulfated dermatan sulfate in cell and incubation medium also did not change. After exposure of macrophages to Escherichia coli for 15 min, the incorporation of [ 35S]sulfate and [ 3H]glucosamine into the glycosaminoglycans was increased by about 40% with no significant change in the proportion of synthesized oversulfated dermatan sulfate, but the relese of glycosaminoglycans into the culture medium remains essentially unchanged. The difference of the existence of oversulfated dermatan sulfate is not yet understood.