Citrulline protects human retinal pigment epithelium from hydrogen peroxide and iron/ascorbate induced damages

Abstract

Oxidative stress appears to play an important role during ageing of the retina and in the pathophysiology of retinal diseases, such as age-related macular degeneration (ARMD). [1][2][3] The retinal pigment epithelium (RPE), localized between the choroid and the neural retina, is particularly vulnerable to oxidative damage caused by reactive oxygen species (ROS). 4 Hydrogen peroxide (H 2 O 2 ) is a ROS generated during RPE phagocytosis of photoreceptor outer segments 5,6 and during light irradiation of melanin present in the RPE. 7 This oxidant is also produced by the photo-excited lipofuscin that accumulates with age in the RPE, and its accumulation is associated with ARMD. 8 Also, it has been reported that iron levels increase in RPE during ageing and that age-dependent iron accumulation is accelerated in patients with ARMD. [9][10][11] Additionally, accumulation of iron can be toxic to the RPE. Indeed, the increase of intracellular ferrous iron produces hydroxyl and lipid alkoxyl radicals through the Fenton reaction, leading to lipid peroxidation and protein oxidation. 12,13

L-Citrulline Supplementation Reduces Blood Pressure and Myocardial Infarct Size under Chronic Intermittent Hypoxia, a Major Feature of Sleep Apnea Syndrome

“…Our results showed that citrulline prevented the IH-increase in O 2 − and XOX activity and also decreased infarct size without any modification in the eNOS activity and expression ( Figure S3c,d ). This is in agreement with other studies highlighting the potential anti-oxidant effects of citrulline: an increase in SOD activity and a decrease in lipid peroxidation in the heart tissue in a rat model of sepsis [ 66 ]; a blunt in H 2 O 2 − induced ROS production in retinal epithelial cells while limiting lipid peroxidation and preventing cell death [ 67 ]; a renal decrease in oxidative-DNA damage without affecting the eNOS expression in spontaneously hypertensive rats [ 35 ]. This suggests that citrulline can preserve the heart against oxidative stress without any modification of the eNOS expression.…”