Therapeutic effects of TACI-Ig on rats with adjuvant-induced arthritis via attenuating inflammatory responses

To investigate the effects of TACI-Ig, a recombinant fusion protein that modulates B- and T-cell activation by binding and neutralizing B-lymphocyte stimulator (BLyS) and a proliferation-inducing ligand (APRIL), in an established adjuvant-induced arthritis (AA) rat model. Rats with experimental arthritis were randomly separated into different groups and then treated with TACI-Ig (0.7, 2.1, 6.3 mg/kg), rhTNFR-Fc (2.8 mg/kg), MTX (0.5 mg/kg) or IgG-Fc (6.3 mg/kg), from Day 16 to Day 34 after immunization. Arthritis was evaluated by hind paw swelling, polyarthritis index and histopathological examination. Activities of BLyS, APRIL, IL-1β, IL-2, IL-10, TGF-β1, PGE(2), TNF-α, IFN-γ, immunoglobulin (Ig)G1, IgG2a, IgM and IgA were assessed by ELISA. Cluster of differentiation (CD)20 expression was detected by immunohistochemical analysis. TACI-Ig (2.1, 6.3 mg/kg) treatment significantly reduced the severity of established arthritis using the methods of clinical observation and histopathological examination. TACI-Ig treatment inhibited expression of IgM, decreased the expression of BLyS and APRIL and regulated the balance of pro-inflammatory and anti-inflammatory cytokines in serum of AA rats. Immunohistochemical analysis demonstrated that CD20 production was reduced in spleen. Data presented here demonstrate that administration of TACI-Ig significantly attenuates progression of experimental arthritis, with reductions in inflammatory response and bone and joint destruction.