Chapters authored
Oxidative Stress in Urolithiasis
Oxygen is absolutely essential for the survival of our life. However, metabolic consumption of oxygen inevitably yields reactive oxygen species (ROS). Imbalance of ROS production and antioxidant capacity causes oxidative stress that potentially damages biomolecules leading to cell injury and death. In fact, ROS have two-faceted functions. Under physiologic condition, ROS function as signaling molecules and participate in maintaining redox balance. In pathology, ROS induce oxidative stress that critically involves in the development of several diseases including urolithiasis (UL). UL or urinary stone disease is a common urologic condition in all countries with progressively increasing prevalence. Most of UL are multifactorial with polygenic susceptibility and highly recurrent nature. Formation of urinary stones is driven by supersaturation of urinary lithogenic ions, and calcium oxalate (CaOx) is the most prevalent stone type. Oxidative stress clearly plays an active role in UL development. In vitro lithogenic crystals induce ROS generation in renal tubular cells leading to oxidative stress, cell injury and release of inflammatory mediators. In nephrolithic rats, oxidative stress and CaOx deposit are gradually increased in the rats’ kidneys. Intervention with antioxidants efficiently reduces oxidative damage and crystal deposits. Human studies show that patients with UL have increased oxidative stress and renal tubular injury relative to the non–stone-forming individuals. Increased oxidative lesions and inflammation are observed in the stone-containing kidneys of the patients. Furthermore, renal fibrosis mediated through tubular epithelial-mesenchymal transition is observed in kidneys of stone patients. Increased renal fibrosis is significantly associated with decreased kidney function. From therapeutic point of view, nutraceutical regimens that are able to reduce oxidative stress may be clinically useful alternatives for preventing stone formation and recurrence. This chapter has an intention to provide a basic knowledge of ROS generation and oxidative stress and up-to-date research findings of oxidative stress in UL based on the published articles as well as the author’s studies.
Part of the book: Reactive Oxygen Species (ROS) in Living Cells