The leptin/adiponectin ratio: potential implications for peritoneal dialysis

Abstract

Leptin and adiponectin are adipokines with respective pro-atherogenic and anti-atherogenic properties, defining the plasma leptin/adiponectin ratio as a novel marker for atherosclerosis. In non-renal patients, both hyperleptinemia and hypoadiponectinemia are associated with cardiovascular complications. In peritoneal dialysis (PD) patients, the leptin/adiponectin ratio is markedly elevated, which is consistent with their increased cardiovascular risk. As glucose metabolism regulates adipokines, we hypothesized that glucose and/or other PD fluid components may affect adipokine production balance. This review summarizes the available data arising from research in this area. In 3T3-L1 adipocytes, glucose-based PD4 1.36% significantly increased leptin secretion vs amino-acid-based (AA) and icodextrin (ICOD)-based PD fluids. In contrast, adiponectin secretion was significantly reduced by PD4 1.36% vs glucose-free dialysates. Glucose concentration in PD fluids was shown to determine leptin secretion. Preliminary data from PD patients showed that a single 6-h dwell with PD4 3.86% glucose acutely increased plasma leptin vs AA (P<0.05). The reduction in glucose load in a standard PD regimen was associated with an improvement in the plasma leptin/adiponectin ratio at 6 months. pH-neutral PD fluids increased leptin secretion in vitro vs acidic PD fluids, without effect on adiponectin. Whether this effect may have an impact on plasma leptin levels in PD patients is unknown. In conclusion, glucose-based PD fluids worsen the adipokine production balance in vitro while glucose-free solutions improve it. In PD patients, hypertonic glucose-based PD fluids may increase plasma leptin levels. Glucose-sparing PD regimens appear to improve the leptin/adiponectin ratio. However, their potential to reduce cardiovascular complications needs to be demonstrated.