Abstract
Purpose :
Royal college of surgeon (RCS) rat is a traditional rodent model of inherited retinitis pigmentosa (RP). We evaluated the immune-microenvironment of RCS rats for investigating the cellular and molecular mechanism during retinal degeneration. To explore the immune-microenvironment of the retinas at different stages, we observed the temporal and spatial variation of IFN-γsecreting T lymphocytes and natural killer(NK) cells in RCS retinas throughout the process of retinal degeneration.
Methods :
RCS rats were divided into early stage (P20d), middle stage(P40d) and late stage(P60d) groups according to their post-natal days and retinal physiopathological changes, same post-natal day of RCS-rdy+-P+rats served as control. Relative expression of IL2, CCL2, CXCL9, CXCL10, CXCL11 and IFN-γmRNA in the retinas were analyzed. Expression of IFN-γand immune cells surface marker CD4, CD8 and CD161 were detected in the retinas by IHC staining. Percentage of IFN-γpositive T lymphocytes and NK cells in rat retina were analyzed by flow cytometry. The concentration of IFN-γin rat retina homogenate were evaluated by ELISA.
Results :
Relative expression of IL2, CCL2, CXCL9, CXCL10, CXCL11 and IFN-γmRNA were significantly higher in RCS group compared to control group, more pronounced at the late stage of RP. Expression of chemokines and cytokines in RCS retinas elevated over post-natal days. IFN-γpositive T lymphocytes(CD4+/CD8+) and NK cells(CD161+) distributed mainly in the internal layer of RCS retina according to the histological cryo-sections. Flow cytometry analysis of rat retina reveals that the percentage of CD4+T lymphocytes (9.09%±0.89%), CD8+T lymphocytes (18.77%±0.38%) and CD161+NK cells (9.41%±0.38%) in RCS retina were significantly higher than control group, and most of these cells were IFN-γpositive. ELISA of retina homogenate demonstrated that the concentration of IFN-γin RCS retina elevated throughout the degenerative process, and significantly higher than control group at the late stage of RP.
Conclusions :
Along with the process of retinal degeneration, immune privilege balance in the retinas got disrupted, and the expression of lymphocytes related chemokines and cytokines elevated due to the breach of BRB (blood-retinal barrier. Lymphocytes infiltrated in the RCS retinas and highly activated at late stage of RP, and the expression of the inflammatory cytokine IFN-γsignificantly increased in degenerated retina.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.