Photocytotoxicity of white light-emitting diode irradiation on human lens epithelium and retinal pigment epithelium via the JNK and p38 MAPK signaling pathways

Abstract

WLEDs have lately been the preferred lighting device based on properties such as energy saving, high efficiency, longevity, and environmental protection. However, studies on the safety of white light-emitting diode (WLED) are limited. In our previous study, we found that WLED light (4000 K ± 500 K color temperature, 250 lx, and 20 min exposure) is photocytotoxic to three mammalian cell lines by causing cell lipid peroxidation. To further investigate the potential photocytotoxicity of WLEDs on the human body, we used two human eye cell lines SRA01/04 and D407 as target cells for evaluating its potential phototoxicity on the human eye in the present study based on cell viability, apoptosis, and intracellular oxidative stress assays, as well as the activation levels of reactive oxygen species (ROS)-related apoptosis pathways, including extracellular signal-regulated kinase (ERK), c-Jun NH2-terminal kinase (JNK) and p38 kinase (p38), using mitogen-activated protein kinase (MAPK) signaling pathway assays. The results showed that WLED light has photocytotoxicities on SRA01/04 and D407 cells, which were both in a time-, irradiance-, and color temperature-dependent manner and strongest at the conditions of 2 h irradiation time, 60 W/m2 irradiance, and 4000 K color temperature. Moreover, the photocytotoxicity of red light-emitting diode (LED) light was the strongest in the three tested monochromatic light compositions of WLED. Mechanism studies show that the potential phototoxicity of WLED on human lens epithelium and retinal pigment epithelium may be caused by its induced oxidative stress damage via the JNK and p38 MAPKs pathways.