gms | German Medical Science

Background: Age-related macular degeneration (AMD), leading cause of blindness in the elderly population, is caused by a combination of genetic predisposition, age and external environmental factors. About 50% of the patients affected with AMD are carriers of polymorphisms in complement factor H (CFH) gene, key regulatory factor of the complement system. CFH has been recently associated with impairment in retinal development, mitochondria stability and redox balance at systemic level. Retina homeostasis and energy demand relies on RPE cells machinery. Therefore we investigated whether CFH loss alters energy metabolism and oxidative stress response of RPE cells.

Methods: Using RNA interference, we reduced CFH levels in RPE human cell lines hTERT-RPE-1. We assessed the effects of CFH depletion in RPE cells via viability and cytotoxicity assays under normal conditions or under H2O2-induced oxidative stress. We used the Seahorse XFp Analyzer to measure bioenergetics, in particular oxygen consumption rate (OCR) and extra cellular acidification rate (ECAR). In parallel we measured the levels of lipid peroxidation.

Results: In CFH absence, cytotoxicity in RPE cells was increased, while oxidative stress had only a mild effect. A minor, but significant decrease in cell viability was observed, amplified by H2O2 pre-treatment. Bioenergetics analyses revealed a reduction in cell energy metabolism in the absence of CFH. Indeed, both mitochondrial respiration and glycolysis rate were reduced after CFH depletion. At the same time CFH loss led to a significant increase in lipid peroxidation, key aspect of AMD pathogenesis.

Conclusion: Our data highlighted the involvement of CFH in RPE cells energy metabolism and oxidative stress response. Indeed we showed that CFH absence leads to a metabolic switch toward a less energetic phenotype and impairs the antioxidant capacity of RPE cells. These findings contribute to elucidate the role of CFH in RPE cells and AMD pathogenesis.