Non-canonical roles of CFH in retinal pigment epithelial cells revealed by dysfunctional rare CFH variants

Complement Factor H (CFH) common genetic variants have been associated with age-related macular degeneration (AMD). While most previous in vitro RPE studies focused on the common p.His402Tyr CFH variant, we characterized rare CFH variants that are highly penetrant for AMD using induced pluripotent stem cell derived retinal pigment epithelium (iPSC-RPE). Our results show that lower FH levels were detected in AMD RPE, which potentially disrupted canonical and non-canonical roles of FH. Specifically, AMD RPE displayed higher inflammation rate and a reduced set of differentially expressed genes compared to control RPE upon A2E and blue light challenge. Additionally, cholesterol efflux and POS phagocytosis defects, dysregulated complement levels, larger sub-RPE deposits and increased mitochondrial stress were observed in AMD RPE. Thus, our study reveals new non-canonical roles for FH in regulating important RPE functions. Overall design: RPE cells were exposed to 5 µM A2E for three days followed by blue light exposure for 10 minutes on the fourth day. On the fifth day supernatant and cells were collected for ELISA and RNAseq respectively. Control cells were treated with DMSO and exposed to light or DMSO without light. Untreated samples were also cultured under the same conditions as A2E and DMSO treated samples and collected as controls at the end of the experiment.