ANGPTL4 promotes choroidal neovascularization and subretinal fibrosis through the endothelial‒mesenchymal transition

This study aimed to investigate the possible mechanisms by which ANGPTL4 is involved in the pathogenesis of choroidal neovascularization (CNV) and subretinal fibrosis.

Differentially expressed genes in retinal pigmented epithelium (RPE)-choroid-sclera complex tissues from nAMD patients and control individuals were identified via the GEO database, followed by GO and KEGG analyses. A Venn diagram was used to identify EndMT-related DEGs. A logistic regression model was constructed to screen for prognostic genes. Laser-induced CNV mouse models were established and validated with FFA and OCTA. The expression of ANGPTL4 and EndMT-related markers in the RPE-choroid-sclera complex was measured via RT‒qPCR and Western blotting. TGF-β2-induced HUVECs were used as EndMT cell models, and specific siRNAs targeting ANGPTL4 (si-ANGPTL4) were designed and screened. The effects of ANGPTL4 knockdown on the migration and invasion of HUVECs were also examined. Laser-induced CNV mouse models were constructed, and an intravitreal injection of cholesterol-modified si-ANGPTL4 was used to knock down ANGPTL4. FFA, OCTA and immunofluorescence staining were used to observe CNV formation and subretinal fibrosis, and the expression of ANGPTL4 and EndMT-related markers was determined.

ANGPTL4 expression was significantly increased in mice with CNV and colocalized with IB4. In TGF-β2-induced EndMT, ANGPTL4 was also upregulated, and its knockdown led to the inhibition of EndMT and cell migration and invasion, while its overexpression promoted the EndMT process. ANGPTL4 knockdown reduced the formation of CNV and subretinal fibrosis in mice with CNV by suppressing EndMT.

ANGPTL4 may promote CNV and subretinal fibrosis through EndMT, suggesting that ANGPTL4 may be a novel potential target for nAMD therapy.