INTERLEUKIN-1-BETA-MODULATED GENE-EXPRESSION IN IMMORTALIZED HUMAN CHONDROCYTES

Immortalized human chondrocytes were established by transfection of pr imary cultures of juvenile costal chondrocytes with vectors encoding s imian virus 40 large T antigen and selection in suspension culture ove r agarose. Stable cell lines were generated that exhibited chondrocyte morphology, continuous proliferative capacity (> 80 passages) in mono layer culture in serum-containing medium, and expression of mRNAs enco ding chondrocyte-specific collagens II, IX, and XI and proteoglycans i n an insulin-containing serum substitute. They did not express type X collagen or versican mRNA. These cells synthesized and secreted extrac ellular matrix molecules that were reactive with monoclonal antibodies against type II collagen, large proteoglycan (PG-H, aggrecan), and ch ondroitin-4- and chondroitin-6-sulfate. Interleukin-1 beta (IL-1 beta) decreased the levels of type LI collagen mRNA and increased the level s of mRNAs for collagenase, stromelysin, and immediate early genes (eg r-1 c-fos, c-jun, and jun-B). These cell lines also expressed reporter gene constructs containing regulatory sequences (-577/+3,428 bp) of t he type II collagen gene (COL2A1) in transient transfection experiment s, and IL-1 beta suppressed this expression by 50-80%. These results s how that immortalized human chondrocytes displaying cartilage-specific modulation by IL-1 beta can be used as a model for studying normal an d pathological repair mechanisms.