Modulation of hyaluronan fragmentation by interleukin-1 beta in synovial membrane cells

Abstract

Hyaluronan (HA) plays a crucial role in the lubricating and buffering properties of synovial fluid. The purpose of this study was to examine the effects of interleukin (IL)-1beta on HA degradation in cultured synovial membrane cells. The rabbit synovial membrane cell line HIG-82 was cultured with and without IL-1beta. The amounts of HA of varying molecular weights in the medium were analyzed using high-performance liquid chromatography, the mRNA levels of HA synthase (HAS) and hyaluronidase (HYAL) were analyzed by means of real-time PCR, and HYAL activity was analyzed by HA zymography. The amounts of HA with a molecular weight lower than 300 kDa, and between 300 and 1900 kDa, in the culture medium of HIG-82 cells were significantly higher in the presence of IL-1beta. However, the amount of HA with a molecular weight greater than 1900 kDa was significantly lower in the presence of IL-1beta. Both HAS2 and HAS3 mRNA levels were upregulated by treatment with IL-1beta. So, too, were the levels of HYAL1 and HYAL2 mRNA, which resulted in enhanced HYAL activity. However, HYAL activity was inhibited by transfection of HYAL2-siRNA. Our results suggest that IL-1beta is a crucial factor in the fragmentation of HA in inflammatory joints.