IL-1β and TGF-β1 modulate the sulphation grade of chondro-disaccharides in porcine articular cartilage: a capillary electrophoresis study

Abstract

This report describes the effect of interleukin-1β IL-1β and transforming growth factor-β1 (TGF-/31) on proteoglycan release from cartilage explants and modification at the sulphation level. Matrix proteoglycans purified by ion-exchange chromatography were composed of two distinct peaks (1 and 2) each showing a different K av value when they were subjected to size-exclusion chromatography on a Sepharose CL-2B column. Glycosaminoglycans (GAGs) of conditioned medium and extracellular matrix proteoglycans were digested by chondroitin ABC and AC lyase, suggesting that chondroitin sulphate (CS) is the major GAG present (80–90%). Structural analysis of disaccharides, by capillary zone electrophoresis, revealed a different pattern of sulphated glycosaminoglycans when cartilage was treated with either IL-1β or TGF-/31. Analysis of GAGS released into the medium from TGF-β1 treated cartilage showed a reduction in the level of 4- S-disaccharide (ΔDi4S) and an increase in non-sulphated disaccharides (ΔDiOS). while no significant changes were found in IL-1β treated cartilage. In the extracellular matrix, IL-1β and TGF-β1 induced a more complex rearrangement of the GAGs. The level of non-sulphated disaccharides was increased whereas that of total sulphated disaccharides was reduced. Taken together, these results suggest that both cytokines modify the structure of GAGS, probably by interfering with the activity or the synthesis of sulphotransferases involved in GAG turnover.