Protective Effect of Pristane on Experimental Autoimmune Uveoretinitis

Abstract

Purpose: : To evaluate the effects of administration of mineral oils on the course of experimental autoimmune uveoretinitis in mice.

Methods: : EAU is induced in mice C57BL/6 (H-2^b) by active immunization with peptide p1-20 of interphotoreceptor retinoid-binding protein (IRBP). Pristane and phytol are given to mice intraperitoneally 5 days before immunization with the retinal antigen. Effects of administration of mineral oils on EAU severity are evaluated clinically by fundoscopic examinations and histological disease scoring. Immunological responses are assessed by measurement of antigen-specific lymphocyte proliferation and cytokine production in primary cultures of spleen and lymph nodes cells.Serum levels of anti-IRBP antibodies are also determined. The phenotypic characteristics of spleen cells are analyzed by flow cytometry. Oxidative stress is evaluated by analysis of reactive oxygen species (ROS) production bythe human retinal pigment epithelial cell line ARPE-19 and human endothelial cells (HUVEC) incubated with sera from mice with uveitis. Immunohistochemistry on retinal pigment epithelium (RPE) flat-mounts using antibodies to occludin and phalloidin is performed one week after IRBP immunization.

Results: : The severity of EAU continuously increases in time for mice treated with PBS and phytol. By contrast, treatment of immunized mice with pristane significantly decreases the clinical severity of the disease (P<0.001). As for unstimulated cells, the production of IFNγ is reduced in IRBP-stimulated lymph node cells supernatants from pristane-treated mice compared with those from PBS and phytol treated-mice (P<0.05). Treatment with pristane induces a 2.4-fold increase in the anti-IRBP IgG1 levels compared to the PBS control group (P<0.05). Specific analysis of the various spleen cells lineages shows significant differences between the various groups. The production of ROS by HUVEC and ARPE-19 cells incubated with sera from pristane-treated mice is significantly decreased compared to sera from control PBS-treated animals. Unlike in PBS and phytol-injected mice, RPE flatmout photographs reveals no disruption of occludin signal in pristane-treated mice.

Conclusions: : If phytol administration has no effect of EAU severity, pristane injection prevents EAU by inducing a protective Th2 biased autoimmune response and by inhibiting the permeability of the outer blood-retina barrier.

Keywords: uveitis-clinical/animal model • immunomodulation/immunoregulation • oxidation/oxidative or free radical damage