Toxic synergy between wood combustion smoke components and high energy visible light on retinal pigment epithelial cells

Blue light, also known as high energy visible (HEV) light, is the most energetic light reaching the adult retina. HEV light exerts its toxicity mainly through chromophore photosensitization reactions. Some components found in atmospheric pollution can absorb light and act as exogenous chromophores. This study aims to assess the impact of the co-exposure to HEV light and wood combustion smoke extract, on retinal pigment epithelium (RPE) cells. We show that these two factors act in synergy causing RPE cell viability loss. Co-exposure to HEV light and wood smoke extract leads to oxidative stress that can be mitigated by antioxidant. This indicates the presence of HEV light-sensitive chromophore(s) amongst the wood smoke components. In response to the oxidative stress induced by wood smoke and HEV light, RPE cells activate the detoxification pathway nuclear factor erythroid 2-related factor 2 (Nrf2). Our results bring the first evidence that co-exposure to smoke from wood combustion and light is toxic for human retina.