Over-expression Of Angiotensin-converting Enzyme2(ACE2) Ameliorates Amyloid Β-induced Inflammatory Response In Human Primary Retinal Pigment Epithelium

PURPOSE: Amyloid-β(Aβ)is a major constituent of drusen which is a hallmark of early age-related macular degeneration(AMD).The purpose of this study is to investigate whether enhancement of ACE2,an important component of the protective ACE2/Ang-(1-7)/Mas axis of the renin angiotensin system(RAS),ameliorates Aβ-induced inflammatory response in human RPE cells.METHODS: Annexin-V FITC/PI assay and Cell counting kit-8(CCK-8)were used to determine the optimum concentration and incubation time of Aβ1-42.ACE2 plasmid was transfected into primary cultured human retinal pigment epithelia(h RPE)and ARPE-19 cells for 6 hours followed by stimulation with Aβ1-42 at the concentration of 1 μM for 48 hours.The gene expression was detected by real-time PCR and the protein levels were determined by Western blotting or ELISA.A779,an antagonist of Ang-(1-7),was employed to further confirm the involvement of ACE2/Ang-(1-7)/Mas axis.RESULTS: Flow cytometry and CCK-8 showed that the optimal concentration of Aβ1-42 was 1 μM and the optimal incubation time was 48 hours.Aβ1-42 up-regulated the expression of IL-1β and MCP-1.ACE2 plasmid significantly up-regulated the expression of ACE2 and Ang-(1-7)in hRPE and ARPE-19 cells.Activation of ACE2 reduced the over-production of inflammatory cytokines at both mRNA and protein levels in h RPE and ARPE-19 cells stimulated with Aβ1-42.Furthermore an antagonist of Ang-(1-7),A779 reversed the anti-inflammatory effect of ACE2.CONCLUSIONS: Over-expression of ACE2 ameliorates Aβ-induced inflammatory response by activating the ACE2/Ang-(1-7)/Mas axis in human RPE cells.Our data suggest that ACE2/Ang-(1-7)/Mas axis may be a promising target for developing novel therapies for inflammation response in AMD.