NOS2 and chronic kidney disease: Increased oxidative stress in CKD, similarly to other pro-oxidant states, is characterized by excessive generation of oxidant compounds due to activation and upregulation of various enzymatic pathways including nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, lipoxygenase, xanthine oxidase, uncoupled nitric oxide synthase (NOS), and the mitochondrial respiratory chain [12, 13].