Upregulation of CD44 mRNA expression by interleukin-1β in cultured rabbit articular chondrocytes

Abstract

We investigated the effects of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) on CD44 mRNA expression in cultured rabbit articular chondrocytes. High-density-suspension-cultured chondrocytes were exposed to IL-1β (0.1, 1, or 10 ng/ml) or TNF-α (0.1, 1, or 10 ng/ml). Quantitative detection of specific mRNA for CD44 was carried out by reverse transcription, polymerase chain reaction (RT-PCR). Furthermore, to determine the degradation of cartilage matrix by IL-1β and TNF-α, the concentrations of chondroitin 4-sulfate (C4S) and chondroitin 6-sulfate (C6S) released to the culture medium were measured with high-performance liquid chromatography (HPLC). CD44 mRNA expression was increased significantly in chondrocytes cultured with IL-1β, but not in the chondrocytes cultured with TNF-α. The release of chondroitin sulfates (C4S+C6S) to the culture medium was also accelerated by IL-1β but was not affected by TNF-α. These results suggest that IL-1β can promote CD44 mRNA expression, together with the degradation of the cartilage matrix, and may assist in binding hyaluronic acid (HA) and CD44 in the chondrocytes.