Increased polymorphonuclear leukocyte respiratory burst function in type 2 diabetes

Abstract

The predisposition to infection and chronic inflammation in diabetes may in part be related to the effects of hyperglycemia or other metabolic abnormality on polymorphonuclear leukocytes (PMN). We evaluated oxidative respiratory burst activity (superoxide production) in non-stimulated and stimulated PMN from 70 stable type 2 Hispanic diabetic patients, as compared to 70 healthy Hispanic individuals without diabetes. The influences of protein kinase C (PKC) inhibitors and certain antibiotics on superoxide production were examined. Both resting and stimulated (PMA, zymosan) PMN from diabetic individuals produced more superoxide than PMN from controls. Inhibitors of PKC, a possible mediator of the augmented respiratory burst activity, decreased superoxide production in all (resting and stimulated) diabetic and control PMN. Azithromycin, which is markedly concentrated by PMN, profoundly inhibited superoxide generation in all groups of diabetic and control cells. PMN from Hispanic diabetic patients produced greater quantities of superoxide than non-diabetic controls. This increased oxidative respiratory burst activity may predispose to infection and chronic inflammation in diabetes. PKC inhibitors and azithromycin inhibited this respiratory burst response. The possible role of PKC (especially PKC beta) as the mediator of this augmented respiratory burst response requires further evaluation, and may lead to therapeutic studies with appropriate inhibitors.