Attenuation of experimental autoimmune uveitis in Lewis rats by betaine

Abstract

Experimental autoimmune uveitis (EAU) is an animal model of human autoimmune uveitis that is characterized by the infiltration of autoimmune T cells with concurrent increases in pro-inflammatory cytokines and reactive oxygen species. This study aimed to assess whether betaine regulates the progression of EAU in Lewis rats. EAU was induced via immunization with the interphotoreceptor retinoid-binding protein (IRBP) and oral administration of either a vehicle or betaine (100 mg/kg) for 9 consecutive days. Spleens, blood, and retinas were sampled from the experimental rats at the time of sacrifice and used for the T cell proliferation assay, serological analysis, real-time polymerase chain reaction, and immunohistochemistry. The T cell proliferation assay revealed that betaine had little effect on the proliferation of splenic T cells against the IRBP antigen in an in vitro assay on day 9 post-immunization. The serological analysis showed that the level of serum superoxide dismutase increased in the betainetreated group compared with that in the vehicle-treated group. The anti-inflammatory effect of betaine was confirmed by the downregulation of pro-inflammation-related molecules, including vascular cell adhesion molecule 1 and interleukin-1β in the retinas of rats with EAU. The histopathological findings agreed with those of ionized calcium-binding adaptor molecule 1 immunohistochemistry, further verifying that inflammation in the retina and ciliary bodies was significantly suppressed in the betaine-treated group compared with the vehicle-treated group. Results of the present study suggest that betaine is involved in mitigating EAU through anti-oxidation and anti-inflammatory activities.