Interleukin-1? down-regulates the expression of glucuronosyltransferase I, a key enzyme priming glycosaminoglycan biosynthesis: Influence of glucosamine on interleukin-1?-mediated effects in rat chondrocytes

Abstract

Objective To assess the variations of galactose‐ β‐1,3‐glucuronosyltransferase I (GlcAT‐I) expression related to the decrease in proteoglycan synthesis mediated by interleukin‐1β (IL‐1β) in rat chondrocytes, and to evaluate the influence of glucosamine on the effects elicited by this proinflammatory cytokine. Methods Rat articular chondrocytes in primary monolayer cultures or encapsulated into alginate beads were treated with recombinant IL‐1β in the absence or presence (1.0–4.5 gm/liter) of glucosamine. Variations of GlcAT‐I and expression of stromelysin 1 (matrix metalloproteinase 3 [MMP‐3]) messenger RNA (mRNA) were evaluated by quantitative multistandard reverse transcriptase–polymerase chain reaction. In vitro enzymatic activity of GlcAT‐I was measured by thin‐layer chromatography, with radiolabeled UDP‐glucuronic acid and a digalactoside derivative as substrates. Proteoglycan synthesis was determined by ex vivo incorporation of Na2‐35SO4. Nitric oxide synthase and cyclooxygenase activities were monitored by the evaluation of nitrite (NO −2) and prostaglandin E2 (PGE2) produced in the culture medium, respectively. Results IL‐1β treatment resulted in a marked inhibition of GlcAT‐I mRNA expression and in vitro catalytic activity, together with a decrease in proteoglycan synthesis. In addition, glucosamine was able to prevent, in a dose‐dependent manner, the inhibitory effects of IL‐1β. In the same way, the amino sugar reduced NO −2 and PGE2production induced by IL‐1β. Finally, the up‐regulation of stromelysin 1 (MMP‐3) mRNA expression by IL‐1β was fully prevented by glucosamine. Conclusion The results of this study suggest that the deleterious effect of IL‐1β on the anabolism of proteoglycan could involve the repression of GlcAT‐I, a key enzyme in the biosynthesis of glycosaminoglycan. Glucosamine was highly effective in preventing these IL‐1β–mediated suppressive effects. The amino sugar also prevented the production of inflammatory mediators induced by the cytokine. This action could account for a possible beneficial effect of glucosamine on osteoarthritic articular cartilage.

Regulation of Xylosyltransferase I Gene Expression by Interleukin 1β in Human Primary Chondrocyte Cells

“…Chondrocyte Isolation and Culture-Primary chondrocyte cells were isolated from cartilage samples taken from macroscopically normal areas of cartilage knee obtained from 13 individual OA patients (mean age 65 Ϯ 9 years) undergoing total knee replacement as described previously (22). This study was approved by our local research institution (Commission de la Recherche Clinique; registration no.…”

Preventive actions of a high dose of glucosamine on adjuvant arthritis in rats

“…Several short-and longterm clinical trials in osteoarthritis have shown the significant symptom-modifying effect of glucosamine [7 -9]. According to the recent biochemical and pharmacological findings, administration of glucosamine normalizes cartilage metabolism, so as to inhibit the degradation [10] and stimulate the synthesis of proteoglycans [11,12], and to restore the articular function.…”

Glucosamine, a naturally occurring amino monosaccharide, suppresses the ADP-mediated platelet activation in humans

“…Several short-and longterm clinical trials in osteoarthritis have shown the significant symptom-modifying effect of glucosamine [2,3]. According to the recent biochemical and pharmacological studies, administration of glucosamine normalizes cartilage metabolism, so as to stimulate the synthesis and inhibit the degradation of proteoglycans, and to restore the articular function [4,5].…”