| ObjectiveUveitis is characterized as a common cause of blindness.Aryl hydrocarbon receptor（AhR）,a ligand-activated nuclear receptor,has been implicated to play a role in human uveitis,although the exact mechanisms remain poorly understood.The purpose of this study was to enhance our knowledge concerning the role and the underlying mechanism of AhR duringexperimentalautoimmuneuveitis（EAU）using2,3,7,8-tetrachlorodibenzo-p-dioxin（TCDD）,which binds to the AhR with the highest affinity of all known compounds.MethodsA total of 54 female C57BL/6J mice were divided into three groups randomly:the naive group（n=18）,the EAU+vehicle group（n=18）,and the EAU+TCDD group（n=18）.We immunized mice with IRBP651-67051-670 to induce EAU.TCDD was administrated intraperitoneally 1 day before the immunization in the EAU+TCDD group.The EAU+vehicle group received the equal volume of vehicle（olive oil）in the same way.Clinical severity of EAU was evaluated with a slit-lamp microscope after immunization.On day 14 after immunization,eyeballs were cut into sections and stained with Hematoxylin&Eosin Staining.Histopathological changes were investigated and the grading was assessed.Blood-retinal barrier（BRB）integrity was evaluated using Evans Blue and Western blotting images of tight junctions.Apoptosis was measured using TUNEL staining and Western blotting images of apoptosis-associated and anti-apoptotic proteins.Macrophage/microglia activation and polarization were studied by immunofluorescence,immunohistochemical and Western blotting.The protein levels of pro-inflammatory cytokines were tested with ELISA.Signalling pathways were tested using Western blotting.ResultsTCDD caused a significant decrease of clinical and histopathological manifestations,preserved blood–retinal barrier（BRB）integrity,reduced apoptotic cells,inhibited macrophage/microglia activation and shifted their polarization from M1 towards M2.Moreover,decreased expression of pro-inflammatory cytokines including TNF-α,IL-6,IL-1βand inhibition of NF-κB,STAT and Notch pathways were found in EAU mice following TCDD treatment.Conclusion1.AhR activation via TCDD exhibits an immunomodulatory effect in EAU mice.2.Ah R activation via TCDD ameliorates BRB breakdown,inhibites cell apoptosis,promotes macrophages/microglia from M1 towards M2polarization,and reduces secretion of pro-inflammatory cytokines during EAU.3.AhR activation via TCDD may modulates inflammation of EAU mice through inhibiting NF-κB,STAT and Notch pathways. |
