The effect of gene therapy using CTLA4Ig/silica-nanoparticles on canine experimental autoimmune thyroiditis

Background The present study aimed to determine the effect of canine CTLA4Ig on canine autoimmune thyroiditis. In a previous study, we established a canine model of autoimmune thyroiditis by immunizing normal dogs with bovine thyroglobulin. An in vitro study using recombinant CTLA4Ig revealed that this protein can inhibit the expression of Th1-type cytokines and the pro-inflammatory cytokines tested. Methods As a result of the in vitro study, we constructed therapeutic CTLA4Ig/silica-nanoparticles and applied them to the treatment of experimentally induced canine autoimmune thyroiditis. Results Gene therapy resulted in significant reductions in anti-canine-thyroglobulin autoantibody titer, anti-T4 antibody titer and T-cell proliferation against thyroglobulin and in the mRNA expressions of interleukin-18 in fresh peripheral blood mononuclear cells (PBMC) from all dogs. There was also a significant reduction compared to day 0 in tumor necrosis factor-alpha and interferon-gamma levels in the supernatant from cultured PBMC. Conclusions The CTLA4Ig-induced suppression of Th1 cytokines is relatively more significant than it appears because autoimmune thyroiditis is a Th1-polarized disease. Thus, CTLA4Ig can improve Th1/Th2 cytokine balance in autoimmune thyroiditis by downregulating Th1 cytokines. Copyright (C) 2008 John Wiley & Sons, Ltd.