Carnosine, carnosinase and kidney diseases

Carnosine (beta-alanyl-L-histidine) is an endogenously synthesized dipeptide which is present in different human tissues, including the kidney. Carnosine is hydrolyzed by the enzyme carnosinase. There are two carnosinase homologues: serum secreted carnosinase and non-specific cytosolic dipeptidase, encoded by the genes CNDP1 and CNDP2 respectively and located on chromosome 18q22.3. Carnosine functions as a radical oxygen species scavenger and as a natural angiotensin converting enzyme inhibitor. Carnosine inhibits advanced glycation end product formation and reduces the synthesis of matrix proteins such as fibronectin and collagen type VI of podocytes and mesangial cells. In experimental studies it was shown that carnosine reduces the level of proinflammatory and profibrotic cytokines. It is suggested that carnosine is a naturally occurring anti-aging substance in human organisms with a beneficial effect on the cardiovascular system. This paper reports the results of studies concerning carnosine's role in kidney diseases, particularly in ischemia/reperfusion induced acute renal failure, diabetic nephropathy, gentamicin-induced nephrotoxicity and also in blood pressure regulation. The correlations between serum carnosine and serum carnosinase activity and polymorphism in the CNDP1 gene are analyzed. The role of CNDP1 gene polymorphism in the development of diabetic nephropathy and non-diabetic chronic kidney disease is discussed. Carnosine is engaged in different metabolic pathways. It has nephroprotective features. Further studies of carnosine metabolism and its biological properties, particularly those concerning the human organism, are required.