Treatment of experimental autoimmune uveoretinitis with intravitreal injection of tacrolimus (FK506) encapsulated in liposomes.

PURPOSE. To evaluate the effects of intravitreal injection of liposomes encapsulating tacrolimus (FK506) on experimental autoimmune uveoretinitis (EAU) in Lewis rats. METHODS. Liposomes containing tacrolimus were prepared by reverse-phase evaporation vesicles. EAU was induced in Lewis rats by subcutaneous injection of interphotoreceptor retinoid-binding protein R16 peptide emulsified in adjuvant. Ten days later, rats were intravitreally injected with saline, tacrolimus, tacrolimus-loaded liposomes, or unloaded liposomes. Clinical signs of inflammation and ocular histologic sections were observed and graded. Retinal function was evaluated by electroretinography (ERG). Tacrolimus concentration was determined in the vitreous body and serum by ELISA. Ocular biodistribution of rhodamine-conjugated liposomes containing tacrolimus (tacrolimus-Rh-lip) was analyzed with a laser scanning confocal microscope. To evaluate the systemic effect of intravitreally injected tacrolimus, delayed-type hypersensitivity (DTH) and lymphocyte proliferation assay (LPA) responses were detected. RESULTS. Treatment of EAU with intravitreal injection of liposomal tacrolimus significantly reduced intraocular inflammation and markedly inhibited the development of EAU, as determined in clinical and histopathologic analyses. No toxic effects could be detected as evaluated by ERG. The concentration of tacrolimus in ocular fluids remained for as long as 14 days after liposomal injection of tacrolimus. Confocal microscopy showed a transretinal distribution of the liposomal particles. DTH and LPA responses were not impaired in liposomal tacrolimus-treated rats. CONCLUSIONS. Intravitreal injection of liposomal tacrolimus was highly effective in suppressing the process of EAU without any side effects on retinal function or systemic cellular immunity. This treatment may represent a new option for the management of intraocular inflammation.