Nicotinamide Attenuates the Progression of Renal Failure in a Mouse Model of Adenine-Induced Chronic Kidney Disease.

Nicotinamide adenine dinucleotide (NAD+) supplies energy for deoxidation and anti-inflammatory reactions fostering the production of adenosine triphosphate (ATP). The kidney is an essential regulator of body fluids through the excretion of numerous metabolites. Chronic kidney disease (CKD) leads to the accumulation of uremic toxins, which induces chronic inflammation. In this study, the role of NAD+ in kidney disease was investigated through the supplementation of nicotinamide (Nam), a precursor of NAD+, to an adenine-induced CKD mouse model. Nam supplementation reduced kidney inflammation and fibrosis and, therefore, prevented the progression of kidney disease. Notably, Nam supplementation also attenuated the accumulation of glycolysis and Krebs cycle metabolites that occurs in renal failure. These effects were due to increased NAD+ supply, which accelerated NAD+-consuming metabolic pathways. Our study suggests that Nam administration may be a novel therapeutic approach for CKD prevention.

Lack of Endothelial Nitric Oxide Synthase Accelerates Ectopic Calcification in Uremic Mice Fed an Adenine and High Phosphorus Diet.

Ectopic calcification is a risk of cardiovascular disease in chronic kidney disease (CKD) patients, and impaired endothelial nitric oxide synthase (eNOS) is involved in the CKD complications. However, whether eNOS dysfunction is a cause of ectopic calcification in CKD remains to be elucidated. To address this issue, we investigated the role of eNOS in ectopic calcification in mice with renal injury caused by an adenine and high-phosphorus (Ade + HP) diet. DBA/2J mice, a calcification-sensitive strain, were fed Ade + HP for 3 weeks. Expression levels of eNOS-related genes were reduced significantly in their calcified aorta. C57BL/6J is a calcification-resistant strain, and wild-type mice showed mild calcified lesions in the aorta and kidney when given an Ade + HP diet for 4 weeks. In contrast, a lack of eNOS led to the development of severe aortic calcification accompanied by an increase in runt-related transcription factor 2, an osteochondrogenic marker. Increased renal calcium deposition and the tubular injury score were remarkable in mice lacking eNOS-fed Ade + HP. Exacerbation of ectopic calcification by a lack of eNOS is associated with increased oxidative stress markers such as nicotinamide adenine dinucleotide phosphate oxidases. In conclusion, eNOS is critically important in preventing ectopic calcification. Therefore, the maintenance of eNOS is useful to reduce cardiovascular disease events and to improve prognosis in CKD patients.