Role of chondrocyte antigen presentation in osteoarthritis

Abstract

Osteoarthritis (OA) is an inflammatory disorder characterized by degeneration of joint components, especially the cartilage. Chondrocytes are found in articular cartilage and play a role in cartilage production and degradation. Several studies found that chondrocytes not only control the cartilage metabolism, but also play a role in immune responses. However, the role of chondrocytes in the pathogenesis of OA is still unclear. In this study, we investigated the responses of OA chondrocytes after stimulating with IFN-γ and proteoglycan aggrecan and also determined antigen presentation function of chondrocytes to present proteoglycan aggrecan peptide to T cells. We found that OA chondrocyte upregulate MHC class I and II on their cell surface after IFN-γ stimulation. Proteoglycan aggrecan peptides, especially P16-31 and P263-280, can stimulate chondrocyte to express CD80 and 86, and secrete high levels of IL-6, IL-8 and TNFα. Moreover, chondrocytes were able to present the P263-280 and P16-31 peptides to autologous T cells isolated from infrapatellar fat pads and stimulated T cell proliferation. These results indicate proteoglycan aggrecan peptides in the presence of IFN-γ induces antigen presentation function of chondrocytes. The knowledge from this study might be used as a foundation for further therapeutic development.