Objective: Members of the suppressor of cytokine signaling (SOCS) family are key negative intracellular regulators of cytokine and growth factor responses, including those that regulate immune responses in autoimmune disorders, such as rheumatoid arthritis (RA). The aim of this study was to investigate modulation of T cell immunity for the treatment of experimental arthritis, via enhanced expression of SOCS-3 in splenic antigen-presenting cells (APCs) obtained after intravenous injection of adenovirus encoding SOCS-3.
Methods: DBA/1 mice were immunized with type II collagen, and adenovirus vectors were administered by intravenous injection before the clinical onset of collagen-induced arthritis (CIA). Splenic cellular responses were analyzed by measuring cytokine production, using Luminex multi-analyte technology. Th cell populations were analyzed by flow cytometry.
Results: Systemic delivery of adenovirus encoding SOCS-3 resulted in enhanced transgene expression in splenic APCs, which led to decreased production of interleukin-23 (IL-23), IL-6, and tumor necrosis factor alpha, but significantly higher production of antiinflammatory IL-10, by these cells. Fluorescence-activated cell sorting analysis showed increased numbers of splenic CD4+ T cells after SOCS-3 treatment. In the presence of SOCS-3-transduced APCs, however, purified splenic CD3+ T cells showed reduced antigen-specific proliferation and a significant reduction in the production of interferon-gamma (-43%), IL-4 (-41%), and IL-17 (-70%). Interestingly, the altered splenic cellular responses were accompanied by a protective effect on CIA development, and histologic analysis of knee joints showed reduced joint inflammation and connective tissue destruction.
Conclusion: This study demonstrates effective prevention of CIA after intravenously induced overexpression of SOCS-3; this is probably caused by the generation of tolerogenic APCs, which have an inhibitory effect on Th1, Th2, and especially, Th17 cell activity.