Antiglycation and antioxidant effect of carnosine against glucose degradation products in peritoneal mesothelial cells.

BACKGROUND/AIM: Toxicity with advanced glycation end products (AGEs) is a major problem in uremic patients. Treatment with peritoneal dialysis (PD) exacerbates AGE formation as a result of bioincompatibility of the conventional peritoneal dialysis fluid (PDF). The presence of glucose degradation products (GDPs) in PDF is the main cause of its bioincompatibility. Carnosine is an endogenous dipeptide with a powerful antiglycation/antioxidant activity. In an attempt to improve PDF biocompatibility, we evaluated the effect of carnosine in human peritoneal mesothelial cells (HPMC) incubated with PDF or GDPs in vitro. METHODS: HPMC were incubated for short or prolonged time with PDF in the presence or absence of carnosine. Similarly, HPMC were incubated in the same condition but with a combination of GDPs. Following the incubation, cells were tested for their viability, protein carbonyl content and reactive oxygen species (ROS) production. RESULTS: Results demonstrated a significant protective effect of carnosine to HPMC in both acute and chronic conditions with PDF or GDPs as judged by the enhancement of cell viability, preserved protein from modification and decreased ROS production. CONCLUSION: Carnosine enhanced HPMC viability against the toxic effect of GDPs probably through protection of cellular protein from modification and from ROS-mediated oxidative damage. The salutary effect of carnosine may render it a desirable candidate for improving PDF biocompatibility and reducing AGE complications in PD patients.

Decreased formation of advanced glycation end-products in peritoneal fluid by carnosine and related peptides.

BACKGROUND: Formation of advanced glycation end-products (AGEs) is a major problem in uremic patients treated with peritoneal dialysis (PD). Application of additives with known anti-glycosylation properties to PD fluid may be beneficial in minimizing the formation of AGEs. This study aimed to evaluate the effect of carnosine and its related peptides homocarnosine and anserine against the formation of AGEs in PD fluid. METHODS: PD solutions (1.5% dextrose) were incubated with human serum albumin (HSA) or collagen (type IV) with or without 10 mmol/L of each of carnosine, anserine, homocarnosine, histidine, and aminoguanidine. The formation of AGEs was followed by fluorescence spectrophotometry at weekly intervals for 7 weeks. For the determination of the acute effect of carnosine and related compounds, HSA and collagen were incubated with 4.25% dextrose PD solutions for 24 hours, followed by incubation with 20 mmol/L of carnosine and related compounds for another 24 hours. The rate of AGE formation was monitored by fluorescence spectrophotometry. RESULTS: Carnosine and related compounds showed effective regression in AGE formation in both types of proteins in both long- and short-term exposure to PD fluids at a rate of effectiveness of the order of carnosine > homocarnosine > anserine, aminoguanidine > histidine in long-term exposure, and homocarnosine > carnosine > aminoguanidine > anserine > histidine in short-term exposure. CONCLUSION: Carnosine and related peptides could suppress the formation of AGEs initiated by PD fluid. This observation may provide a new therapeutic approach for the prevention and treatment of the AGE-related complications in PD patients.