The role of iron in oxidative stress accelerated endothelial dysfunction in chronic kidney disease

Abstract

Chronic kidney disease (CKD) is growing global public health problem affecting 1 in 10 adults in developed countries and recognised as an important risk factor for cardiovascular disease (CVD) development. CVD is the main cause of death among CKD patients. Endothelial injury and dysfunction are critical steps in atherosclerosis, a major CVD. Oxidative stress (increased level of reactive oxygen species, ROS) has been associated with CVD development. Intravenous (IV) iron preparations are widely used in the management of CKD mediated anaemia, and have been associated with increased oxidative stress and cellular dysfunction. This study examined the effect of pharmacologically-relevant concentrations of IV Venofer (iron sucrose) or IV Ferinject (Ferric carboxymaltose, FCM) on primary human umbilical vein endothelial cell (HUVEC) activation/damage and on intracellular ROS generation as well as studying the potential mechanisms responsible. Data from TUNEL assay and Annexin V-FITC/PI staining showed that, IV FCM had no effect, but IV iron sucrose increased HUVEC apoptosis at 24hr. IV iron sucrose inhibited cell proliferation and reduced cell viability. Both compounds induced EC activation through sustained activation of p38 MAPK and up-regulation of ICAM-1 and VCAM-1. Additionally, the compounds induced significant increase in total ROS and superoxide anion production, which was attenuated by the anti-oxidant N-acetylcysteine (NAC). P38 MAPK showed up-regulation of pro-apoptotic protein Bax and down-regulation of antiapoptotic Bcl-2 protein in HUVEC treated with IV iron sucrose and p38 inhibition reversed these effects. In summary, these results suggest that IV iron sucrose causes more severe EC injury than IV FCM. However, both IV iron preparations induced intracellular ROS and superoxide anion generation in HUVEC leading to EC activation/dysfunction, providing a potential explanation for vascular damage in CKD patients.