Objective To investigate whether TO90 inhibits angiotensin Ⅱ(Ang Ⅱ)-induced inflammatory response by regulating the expressions of ACE2/Ang-(1-7)/MAS receptor axis in human retinal pigment epithelial cells. Methods In vitro cultured ARPE-19 cells were treated with Ang Ⅱ for 48 h

and the changes in the expressions of interleukin-6(IL-6)

IL-8 and monocyte chemoattractant protein-1(MCP-1) were detected using real-time PCR and enzyme-linked immunosorbent assay(ELISA) to verify the establishment of the inflammatory cell model. The effect of TO90 on the inflammatory response of Ang Ⅱ-treated ARPE-19 cells was evaluated by detecting the expression of IL-6

IL-8

MCP-1

ACE2 and MAS receptor using real-time PCR and Western blotting. ARPE-19 cells treated with Ang Ⅱ

TO90+Ang Ⅱ

A779(a MAS receptor inhibitor)+TO90+Ang Ⅱ

or A779+Ang Ⅱ were examined for expressions of IL-6

IL-8

MCP-1

ACE2 and MAS receptors to further explore the effect of TO90 on Ang Ⅱ-induced inflammation response. Results Ang Ⅱ treatment resulted in significantly increased expressions of IL-6

IL-8 and MCP-1 at both the mRNA and protein levels in ARPE-19 cells(P<0.05)

and these effects were obviously attenuated by pretreatment of the cells with TO90(P<0.05)

which also caused significantly increased expressions of ACE2 and MAS receptor in the cells(P<0.05). In ARPE-19 cells treated with TO90+Ang Ⅱ

inhibition of MAS receptor with A779 significantly enhanced the expression of IL-6

IL-8

MCP-1

while inhibited the expression of ACE2 and MAS receptor at both the mRNA and protein levels(P<0.05). Conclusion TO90 inhibits Ang Ⅱ-induced inflammatory response by up-regulating the expressions of ACE2/Ang-(1-7)/MAS receptor axis in ARPE-19 cells.