Free fatty acid receptor 4 activation protects against choroidal neovascularization in mice

To examine whether free fatty acid receptor 4 (FFAR4) activation can protect against choroidal neovascularization (CNV), which is a common cause of blindness, and to elucidate the mechanism underlying the inhibition, we used the mouse model of laser-induced CNV to mimic angiogenic aspects of age-related macular degeneration (AMD). Laser-induced CNV was compared between groups treated with an FFAR4 agonist or vehicle, and between FFAR4 wild-type (Ffar4(+/+)) and knock out (Ffar4(-/-)) mice on a C57BL/6J/6N background. The ex vivo choroid-sprouting assay, including primary retinal pigment epithelium (RPE) and choroid, without retina was used to investigate whether FFAR4 affects choroidal angiogenesis. Western blotting for pNF-& x138;B/NF-& x138;B and qRT-PCR forIl-6, Il-1 beta, Tnf-alpha, Vegf, and Nf-& x138;bwere used to examine the influence of FFAR4 on inflammation, known to influence CNV. RPE isolated fromFfar4(+/+)andFfar4(-/-)mice were used to assess RPE contribution to inflammation. The FFAR4 agonist suppressed laser-induced CNV in C57BL/6J mice, and CNV increased inFfar4(-/-)compared toFfar4(+/+)mice. We showed that the FFAR4 agonist acted through the FFAR4 receptor. The FFAR4 agonist suppressed mRNA expression of inflammation markers (Il-6, Il-1 beta) via the NF-& x138;B pathway in the retina, choroid, RPE complex. The FFAR4 agonist suppressed neovascularization in the choroid-sprouting ex vivo assay and FFAR4 deficiency exacerbated sprouting. Inflammation markers were increased in primary RPE cells ofFfar4(-/-)mice compared withFfar4(+/+)RPE. In this mouse model, the FFAR4 agonist suppressed CNV, suggesting FFAR4 to be a new molecular target to reduce pathological angiogenesis in CNV.