Purpose: To investigate the role and mechanism of oridonin (ORI), a bioactive diterpenoid extracted from the Chinese herbal medicine Rabdosia rubescens, on the integrity of outer blood-retinal barrier (oBRB) during choroidal neovascularization (CNV).
Methods: ARPE-19 cells were exposed to hypoxia and treated with ORI. The expression of ZO-1 and occludin in the axis of TGFβR/SUV39H1/KLF11 was detected by WB, chromatin immunoprecipitation, luciferin report activity assay, and immunofluorescence assay (IF), and the effect of ORI on the barrier properties of ARPE-19 cells was studied. A laser-induced mouse CNV model was constructed, and ORI was administrated by oral gavage. IF on mouse choroid flat mounts was done to confirm the effect of ORI on BRB integrity. Indocyanine green angiography and IF on mouse retina-RPE-choroid flat mounts were performed to determine the effect of ORI on CNV formation and retinal function. Hematoxylin and eosin staining and TUNEL staining were carried out to appraise ocular and systemic cytotoxicity caused by ORI.
Results: ORI protected ARPE-19 cells from hypoxia-induced destruction of barrier properties and promoted the expression of ZO-1 and occludin by the TGFβR/SUV39H1/KLF11 axis, maintaining barrier properties of ARPE-19 cells with hypoxia. ORI improved BRB integrity during laser-induced CNV in mice and mitigated laser-induced CNV formation in mice without any ocular or systemic cytotoxicity (n = 4-5 in each group).
Conclusions: ORI ameliorates BRB integrity and subsequent formation of CNV via regulating the TGFβR/SUV39H1/KLF11 pathway in RPE cells.