Role of adhesion molecules in diabetes mellitus

Insulin differentially regulates monocyte and polymorphonuclear neutrophil functions in healthy young and elderly humans

CONTEXT

Insulin can regulate immune cell function. Aging is associated with various degrees of insulin resistance together with reduced immune cell activity.

OBJECTIVE

We investigated the hypothesis that blood monocytes and polymorphonuclear neutrophils (PMNs) are less responsive to the action of insulin in elderly subjects. DESIGN-INTERVENTION: We evaluated the effect of hyperinsulinemia (0.7 mU/kg(-1) fat-free mass per minute(-1)) on monocyte and PMN activity using a 4-h euglycemic clamp technique.

PARTICIPANTS

Eight young (24 +/- 6 yr old) and nine elderly (69 +/- 4 yr old) healthy volunteers participated in the study.

MAIN OUTCOME MEASURES

Monocyte and PMN receptor expression and density were measured using flow cytometric detection. PMN chemotaxis toward formyl-Met-Leu-Phe (fMLP) was evaluated using a two-compartment chamber. PMN and monocyte phagocytosis was determined by measuring the engulfment of opsonized particles. Microbicidal functions were determined based on the production of reactive oxygen species (ROS) and bactericidal protein by stimulated cells.

RESULTS

The density of PMN and monocyte insulin receptors was not affected by age or insulin clamp treatment regardless of the age. Insulin was able to regulate the expression of receptors involved in PMN action in the young-adult group only. PMN chemotaxis was up-regulated by insulin in both groups. In contrast, although insulin stimulated phagocytosis and bactericidal activity in young-adult subjects, the ability of PMN to adapt to physiological hyperinsulinemia was blunted in the older group. The effect of insulin on monocyte bactericidal properties seemed to be limited, although a suppressive action on fMLP-induced ROS production was detected in young adults.

CONCLUSIONS

We confirmed the presence of the insulin receptor on monocyte and PMN membranes. We revealed that insulin has a limited action on monocyte function. Insulin has a priming effect on the main PMN functions. Immune cell function adapted poorly to insulin infusion in the elderly subjects.

In vivo evidences that insulin regulates human polymorphonuclear neutrophil functions

Polymorphonuclear neutrophils (PMN) are able to destroy invasive mircoorganisms by a wide variety of functions. Whereas insulin does not stimulate hexose transport in PMN, previous reports have clearly shown that this hormone regulates glucose metabolism inside this cell, raising the question of insulin action on PMN functions in humans. It is interesting that in vitro studies established a strong relationship between specific binding of insulin to its PMN membrane receptor and the activation of the main PMN functions. Therefore, investigation in healthy subjects under strict euglycemia and physiological insulinemia was performed to understand the in vivo-specific action of insulin on PMN functions without hyperglycemia interferences. We determined numerous PMN functions before and after hyperinsulinemia (0.5 mU/kg/min) and euglycemia (0.9 g/l) clamp for 4 h in eight adult healthy volunteers (24+/-6 years). The total number of PMN and the number of PMN expressing CD11b, CD15, CD62L, and CD89 were significantly increased over baseline (P<0.001), whereas the density of these receptors was down-regulated (P<0.01) by insulin. PMN chemotaxis (+117%, P<0.05), phagocytosis (+29%, P<0.001), and bactericidal (+17-25%, P<0.001) capacities were increased during the insulin clamp (P<0.05). Therefore, insulin treatment may modulate PMN functions not only by attainment of a better metabolic control, as suggested by in vivo studies in diabetic patients, but also through a direct effect of insulin.

Abciximab reduces mortality in diabetics following percutaneous coronary intervention

OBJECTIVES

We sought to determine whether abciximab therapy at the time of percutaneous coronary intervention (PCI) would favorably affect one-year mortality in patients with diabetes.

BACKGROUND

Diabetics are known to have increased late mortality following PCI.

METHODS

Data from three placebo-controlled trials of PCI, EPIC, EPILOG, and EPISTENT, were pooled. The one-year mortality rate for patients with a clinical diagnosis of diabetes mellitus was compared with the rate for nondiabetic patients treated with either abciximab or placebo.

RESULTS

In the 1,462 diabetic patients, abciximab decreased the mortality from 4.5% to 2.5%, p = 0.031, and in the 5,072 nondiabetic patients, from 2.6% to 1.9%, p = 0.099. In patients with the clinical syndrome of insulin resistance--defined as diabetes, hypertension, and obesity--mortality was reduced by abciximab treatment from 5.1% to 2.3%, p = 0.044. The beneficial reduction in mortality with abciximab use in diabetics classified as insulin-requiring was from 8.1% to 4.2%, p = 0.073. Mortality in diabetics who underwent multivessel intervention was reduced from 7.7% to 0.9% with use of abciximab, p = 0.018. In a Cox proportional hazards survival model, the risk ratio for mortality with abciximab use compared with placebo was 0.642 (95% confidence interval 0.458-0.900, p = 0.010).

CONCLUSIONS

Abciximab decreases the mortality of diabetic patients to the level of placebo-treated nondiabetic patients. This beneficial effect is noteworthy in those diabetic patients who are also hypertensive and obese and in diabetics undergoing multivessel intervention. Besides its potential role in reducing repeat intervention for stented diabetic patients, abciximab therapy should be strongly considered in diabetic patients undergoing PCI to improve their survival.