Glycated Albumin With Loss of Fatty Acid Binding Capacity Contributes to Enhanced Arachidonate Oxygenation and Platelet Hyperactivity: Relevance in Patients With Type 2 Diabetes

Abstract

High plasma concentrations of nonesterified fatty acids (NEFAs), transported bound to serum albumin, are associated with type 2 diabetes (T2D). The effects of albumin on platelet function were investigated in vitro. Modifications of albumin, such as those due to glycoxidation, were found in patients with T2D, and the consequences of these modifications on biological mechanisms related to NEFA handling were investigated. Mass spectrometry profiles of albumin from patients with T2D differed from those from healthy control subjects. Diabetic albumin showed impaired NEFA binding capacity, and both structural and functional alterations could be reproduced in vitro by incubating native albumin with glucose and methylglyoxal. Platelets incubated with albumin isolated from patients with T2D aggregated approximately twice as much as platelets incubated with albumin isolated from healthy control subjects. Accordingly, platelets incubated with modified albumin produced significantly higher amounts of arachidonate metabolites than did platelets incubated with control albumin. We concluded that higher amounts of free arachidonate are made available for the generation of active metabolites in platelets when the NEFA binding capacity of albumin is blunted by glycoxidation. This newly described mechanism, in addition to hypoalbuminemia, may contribute to platelet hyperactivity and increased thrombosis, known to occur in patients with T2D.

Diabetes-induced hepatic oxidative stress: a new pathogenic role for glycated albumin

“…Previous studies reported that oxidative stress and glycation resulted in conformational changes in albumin structure and function in vitro [21,49,50], and recently in vivo by the altered fatty acid binding capacity displayed by albumin isolated from diabetic patients [51]. The present study provides novel insights into redox imbalance in the liver of diabetic/obese mice and highlights.…”

Plasma levels of free fatty acids correlate with type 2 diabetes mellitus

“…Thus, glycation of certain HSA residues appears to be directly linked to its capacity for transporting FFAs. Indeed, Blache et al demonstrated that albumin loses approximately 30% of its FFA binding capacity when incubated with a mixture of glucose and methylglyoxal, yielding Amadori products and advanced glycation end products (AGEs), respectively. Thus, higher degrees of glycation may promote higher levels of unbound circulating FFA, increasing the risk of thrombosis, platelet activation, sudden death, stroke and coronary artery disease .…”

“…Thus, glycation of certain HSA residues appears to be directly linked to its capacity for transporting FFAs. Indeed, Blache et al 56 demonstrated that albumin loses approximately 30% of its FFA binding capacity when incubated with a mixture of glucose and methylglyoxal, yielding Amadori products and advanced glycation end products (AGEs), respectively.…”

Nonesterified Fatty Acids, Albumin, and Platelet Aggregation

“…It is in the context of these previous observations that Blache et al (17) have now investigated the paradigm that the glycation or glycoxidation of albumin is relevant to NEFA-related pathophysiology as such modifications of albumin would potentially result in an impaired binding to NEFAs and an increase in unbound NEFAs and thus to platelet hyperactivity. The authors have shown that glycation of albumin induced in vitro with glucose or methylglyoxal, an advanced glycation end product, leads to a reduction in the binding of NEFA to albumin; these changes were similar to those observed in albumin prepared from patients with diabetes.…”