U211725.pdf (7.02 MB)
Advanced glycation endproducts and oxidative stress from the neutrophil respiratory burst
thesisposted on 2014-12-15, 10:30 authored by Richard K. M. Wong
Advanced Glycation Endproducts (AGEs), resulting from the non-enzymatic reaction of reducing sugars with proteins, accumulate in patients with diabetes mellitus and with advancing age and are implicated in the pathogenesis of vascular disease. Oxidative stress also participates in vascular pathology and has also been reported in the context of diabetes and ageing. This study set out to explore the contribution of AGEs to oxidant stress generation, particularly by examining their effects on the respiratory burst of neutrophils and lymphoblasts. Using chemiluminescence to detect reactive oxygen species (ROS), AGEs did not stimulate the neutrophil respiratory burst directly, but caused a dose-dependent enhancement of the neutrophil respiratory burst in response to a mechanical stimulus (up to 265% +/- 42%, p=0.022) or chemical stimulation with fMLP (formylleucylphenylalanine) 100nM (up to 218% +/- 19%, p<0.001). This phenomenon was immediate and reversible, and depended on the simultaneous presence of AGEs with the additional stimulus; hence AGEs appear to act as neutrophil 'co-agonists'. The in vivo correlates of mechanical and chemical stimulation may be vascular stress and microbial exposure respectively, especially since some acute vascular events have been correlated with infective episodes. The 'co-agonist' effect of AGEs on the neutrophil respiratory burst appears to involve upregulation of the NADPH oxidase enzyme, as evidenced by a DPI-dependent suppression of basal and augmented ROS output. This in turn is dependent upon the generation of arachidonic acid (which may potentiate NADPH oxidase subunit function), via cytosolic phospholipase A2 (cPLA2) activation. The whole process is sensitive to adjustments of the intracellular redox status, implying a role for upstream redox signalling..
Date of award2005-01-01
Awarding institutionUniversity of Leicester