Hyaluronan does not affect cytokine and chemokine expression in osteoarthritic chondrocytes and synoviocytes

Objective: Many studies have evidenced the clinical efficacy of hyaluronan (HA) in the treatment of osteoarthritis (OA). However, human and animal stu dies have described proinflammatory effects of HA on cells not involved in OA. We therefore investigated whether different molecular weight HA prepara tions can affect proinflammatory cytokine (IL1 beta and TNF alpha) or chemo kine (IL8, MCP-1 and RANTES) expression in human chondrocytes and synoviocy tes isolated from OA patients. Design: Human chondrocytes and synoviocytes were cultured in vitro in the p resence or absence of three different purified HA pharmaceutical preparatio ns (1x10(6) Kd, 5x10(5) Kd and 6.5x10(4) Kd) and assessed for the productio n of proinflammatory cytokines and chemokines and their mRNA expression. Results: In basal conditions, both chondrocytes and synoviocytes produce on ly MCP-1 and IL8, along with low quantities of 1L1 beta and TNF alpha, but not RANTES. IL8 production was generally about 100 times higher in chondroc ytes than in synoviocytes. while MCP-1 was roughly twice as high in synovio cytes than in chondrocytes. At the mRNA level, expression of IL1 beta, TNF alpha, IL8, MCP-1 and RANTES did not change in the presence of the three HA preparations either in synoviocytes or in chondrocytes with respect to bas al condition. None of the three different HA preparations significantly aff ected production of IL8 or MCP-1. Conclusions: These data demonstrate that preparations of HA of the same ori gin but with different MWs do not induce proinflammatory cytokines and chem okines expressed by chondrocytes and synoviocytes that are either directly or indirectly involved in OA progression. (C) 2001 OsteoArthritis Research Society International.