Hypoxia Increases the Expression of ICAM-1 in Cultured Human Synovial Fibroblasts / 대한류마티스학회지

ABSTRACT

OBJECTIVE: Hypoxic conditions are thought to be exist in inflamed arthritic synovium.Several in vitro and in vivo studies indicate that hypoxia can initiate events that lead to pro-adhesive changes.Therefore,this study was designed to examine the effects of hypoxia on the expression of ICAM-1 by cultured human synovial fibroblasts. METHODS: Synovial fibroblasts were isolated from patients with RA and cultured at hypoxic condition.To quantify the expression of ICAM-1 mRNA in synovial fibroblasts,RT-PCR was performed.The levels of cytokines in culture supernatants were measured by ELISA.The activation of NF- electrophoretic mobility shift assay.The assay of adhesive reaction between synovial fibroblasts and lymphocytes was performed by photographic evaluation with colloidin blue staining and measurement of fluorescent intensity of BCECFAM in lymphocytes.

RESULTS:

The expression ICAM-1 mRNA was increased at 12 to 48 hours of hypoxic stimuli and peaked at 24 hours (p < 0.01).The concentration of IL-1 and TNF-alpha was increased as the duration of hypoxic stimuli was increased.Hypoxia also induced activatation of NF- microB,which was inhibited by antioxidant (pyrroli-dine dithiocarbamate). Fibroblast-lymphocyte adhesive interaction was increased significantly by hypoxic stimuli (p < 0.01).

CONCLUSIONS:

Synovial hypoxia may have an important role in inflammatory synovitis,in part,as a cause of adhesion molecule (ICAM-1)expression in synovial fibroblasts and recruitment of inflammatory cells.