Recent aspects of the anti-inflammatory actions of glucosamine

Glucosamine, a naturally occurring amino monosaccharide, is present in the connective and cartilage tissues as a component of glycosaminoglycans. Thus, glucosamine has been widely used to treat osteoarthritis, a joint disease characterized by cartilage degeneration, in humans. In addition, glucosamine is expected to exert an anti-inflammatory action, since glucosamine suppresses inflammatory cell activation. To further extend the anti-inflammatory actions of glucosamine, we investigated the effects of glucosamine on synovial cells, endothelial cells and intestinal epithelial cells using in vitro and in vivo systems. Firstly, glucosamine suppressed the IL-1β-induced activation of synovial cells in vitro. Furthermore, glucosamine administration repressed synovial cell hyperplasia, cartilage destruction and inflammatory cell infiltration in rat adjuvant arthritis. Secondary, glucosamine suppressed the TNF-α-induced activation of intestinal epithelial cell HT-29 in vitro. In addition, glucosamine administration improved the clinical symptoms, and colonic inflammation and tissue injury in dextran sulfate sodium-induced colitis in rats. Finally, glucosamine suppressed the TNF-α-induced activation of endothelial cells in vitro. Moreover, glucosamine administration repressed the formation of atherosclerotic lesion and infiltration of inflammatory cells into the lesion in spontaneously hyperlipidemic mice B6 KOR Aposhl. Together these observations support the idea that glucosamine can function as not only a chondroprotective agent but also an anti-inflammatory molecule in the body.