Treatment of autoimmune anterior uveitis with recombinant TCR ligands

PURPOSE. To determine protective properties of recombinant TCR ligands (RTLs) as a new treatment for experimental autoimmune anterior uveitis (AU). RTLs comprise the rat RT1.B β1α1 domains, linked either to the guinea pig MBP_69-89 peptide (RTL201), to the corresponding rat MBP _69-89 peptide (RTL200), or to the cardiac myosin peptide CM-2 (RTL203). METHODS. AU associated with experimental autoimmune encephalomyelitis (EAE) was actively induced in Lewis rats by injection of myelin basic protein emulsified in complete Freund's adjuvant (CFA) or passively by the transfer of pathogenic T cells. Rats received five daily doses each of 300 μg RTL201 in saline, intravenously. Control rats received the same dose of RTL203 or an "empty" β1α1 protein (no peptide). The rats were evaluated for the suppression of clinical and histologic signs of AU. RESULTS. RTL201 prevented active and passive AU and reduced the clinical symptoms of established AU. RTL201 completely prevented clinical and histologic AU in the treated rats, compared with disease progression in the untreated rats or those treated with an "empty" construct. The suppression of clinical AU correlated with a significant reduction in inflammatory cells infiltrating the eyes of the RTL201-treated rats. Furthermore, RTL201 inhibited T cell proliferation, DTH responses, and cytokine mRNA expression in the eye, in contrast to the untreated rats. In comparison with RTL201, RTL200 was less effective in protecting the eye from AU. RTL203 also significantly inhibited clinical AU, but not EAE. CONCLUSIONS. RTL constructs suppressed clinical and histologic AU by inhibiting the systemic activation of specific T cells and preventing the recruitment of inflammatory cells into the eye. These findings suggest a possible clinical application of this novel class of peptide/MHC class II constructs in patients with AU that is mediated by T-cell responses to known antigenic peptides.