AIM: To investigate whether the curcumin reduce retinal inflammation in animal model and human retinal pigment epithelium(ARPE)-19 cells.

METHODS: In vivo, male C57/B6 mice received intraperitoneal injections of curcumin for 3d before intraperitoneal injection of lipopolysaccharide(LPS; 10mg/kg)to induce retinal inflammation. 24h after LPS application, the mRNA levels of pro-inflammatory cytokines were detected by real-time PCR(RT-PCR). Concanavalin A lectin perfusion-labeling technique evaluated leukocyte adhesion to the retinal vasculature. The protein concentration in the anterior chamber was measured with a protein quantification kit. In vitro, ARPE-19 cells were cultured. The optimum concentration of curcumin was detected by cell counting kit-8(CCK-8)assay. Before stimulated with 5 μg/mL LPS, ARPE-19 cells were incubated with or without curcumin for 1h. Pro-inflammatory cytokines were measured by RT-PCR and ELISA. PI3K/Akt expression was analyzed by Western Blotting.

RESULTS: Curcumin pre-treatment led to significant inhibition of EIU-associated leukocyte adhesion to retinal blood vessels and anterior-chamber protein leakage. The mRNA expression level of inflammatory cytokines was also significantly reduced with application of curcumin in vivo, such as IL-1β, IL-6 and TNF-α. Meanwhile, Curcumin significantly attenuated the expression of IL-6, IL-8 and MCP-1 at both mRNA and protein levels in ARPE-19 cells. Curcumin suppressed PI3K/Akt phosphorylation as well as NF-κB activation in LPS-activated ARPE-19 cells.

CONCLUSION: Curcumin plays a preventive effect on LPS-induced retinal inflammation. The beneficial effect appears associated with inhibiting of the PI3k/Akt signaling pathway.