Recent studies have reported that IL 29 acts an inhibitor of human Th2 responses and modulates the Th1/Th2 response by the diminution of IL 13 secretion in vitro. It has been shown that IL 29 specifically upregulates the levels of IL 6, IL 8 and IL 10 secreted by monocytes and also enhances IL 2 dependent proliferation of CD4 CD25 Foxp3 T cells induced by dendritic cells. Interestingly, a recent study has reported that IL 29 plays an important role in the pathogenesis of systemic lupus erythematosus by inducing the secretion of chemokines IP 10, MIG and IL 8 in peripheral blood mononuclear cells. Although accumulated data have indicated a crucial role of IL 29 in modulating immune response and enhancing inflammatory reaction, whether IL 29 is involved in the pathogenesis of RA remains unclear.
In this study, we investigated whether the expression of IL 29 is dysregulated in patients with RA. We found sig nificantly elevated levels of IL 29 in peripheral blood mononuclear cells, serum and synovial fluid of RA patients compared with healthy controls or osteoarthritis patients. Moreover, we identified both synovial macrophages and fibroblasts as the major cellular source for IL 29 expression in RA synovial tissue. Furthermore, our in vitro studies revealed that recombi nant IL 29 can stimulate MH7A cells, a human synovial fibroblast cell line, for enhanced production of proin flammatory cytokines, indicating a novel function of IL 29 in driving synovial inflammation during RA develop ment. Our results further support the hypothesis that IL 29 may play a previously unrecognized role in the patho genesis of RA.
Materials and methods Reagents Human IL 29 ELISA reagent kits were purchased from Adlitteram Diagnostic Laboratories. Rabbit anti human IL 29/IL 28Ra polyclonal antibody, and mouse anti human CD68 monoclonal antibody were purchased from Abcam, mouse anti human fibroblast growth factor basic mono clonal antibody from Millipore, recombinant human IL 29 and TNF a were from Pepro tech. Donkey anti rabbit IgG R and goat anti rabbit IgG/TRITC were from Santa Cruz Biotechnology. DyLight 488 conjugated AffiniPure donkey anti mouse IgG, peroxi dase conjugated sheep anti rabbit secondary antibody and peroxidase conjugated sheep anti mouse secondary anti body were from Jackson Immunoresearch. The Diaminobenzidine substrate kit was from Dako.
PrimeScript RT Mas ter Mix and SYBR Green PCR Master Mix were obtained Drug_discovery from Takara Biotechnology. Dulbeccos modified Eagles medium was from Gibco and fetal bovine serum from Biosource International. Patients and samples Patients with RA, OA and healthy control patients were recruited randomly from the First Affiliated Hospi tal of Nanjing Medical University. Blood samples were collected from 54 RA patients and 60 HC. SF samples were obtained from 20 RA and 20 OA patients. Syno vium samples were obtained from six RA patients and five HC after therapeutic synovectomy or amputation.