Abstract
Purpose:
EtOH-related health problems are a major concern worldwide. EtOH metabolism produces ROS and increasing EtOH catabolic activity implies more ROS production enhancing tissue damage. CYP2E1 metabolizes EtOH leading to production of ROS and acetaldehyde, which are known to cause liver damage. Despite EtOH is mostly catabolized in the liver, the presence of CYP2E1 in other tissues opens the possibility to consider that EtOH could also be processed by a non-hepatic route. Although, the ciliary body presents detoxifying properties, detoxification can also occur in the RPE in view of the expression of diverse CYP450 isoforms. The present study shows a characterization of CYP2E1 in the human RPE cell line ARPE-19 and its inducibility by EtOH. CYP2E1-derived ROS are also proposed as responsible for the EtOH-induced damage in these cells, since chlormethiazol (CMZ, as an inhibitor) or N-acetylcysteine (NAC, as an antioxidant) prevented it.
Methods:
For the present study: XTT assay; qPCR analysis, Western Blot and immunocytochemistry were used after ethanol- and ethanol plus inhibitors-treated ARPE-19 cells.
Results:
CYP2E1 is present in the human retinal pigment epithelium. Additionally, microsomal CYP2E1 expression in these cells was inducible by ethanol. ROS production induced by increasing ethanol concentrations paralleled CYP2E1 increased expression. CYP2E1 inhibition by CMZ or NAC abolished, mRNA and protein expression, as well as ethanol-induced ROS production.
Conclusions:
CYP2E1, a well-known cytochrome that catabolyzes ethanol, is expressed in ARPE-19 cells. CYP2E1 gene transcription and protein expression are enhanced after exposure to ethanol, which in turn results in the generation of more ROS. Inhibition of CYP2E1 with CMZ and NAC reverses all the above.