Elevated plasma levels of soluble receptors of TNF-alpha and their association with smoking and microvascular complications in young adults with type1 diabetes

The purposes of this study were 1) to compare soluble tumor necrosis factor -a receptors, which are thought to reflect the degree of TNF-a activation, in nondiabetic subjects and type I diabetic patients, and 2) to evaluate th e effects of smoking and microvascular complications on soluble tumor necro sis factor-a receptor levels in type 1 diabetic individuals. Plasma soluble tumor necrosis factor-a receptor levels (R1 and R2) were measured in 50 yo ung type I diabetic patients without clinical macroangiopathy and in a matc hed group of 20 healthy volunteers. When diabetic patients were grouped acc ording to smoking and microvascular complication status, the groups of pati ents had similar values of age, sex, body mass index, blood pressure, lipid s, creatinine, and glycometabolic control. Nevertheless, soluble tumor necr osis factor-alpha receptor-R1 levels but not R2 levels, were markedly eleva ted (P < 0.05 or less) in complicated vs. uncomplicated (2.40 +/- 0.3 vs. 1 .80 +/- 0.1 ng(ml) patients and in smokers vs. nonsmokers (2.66 :+/- 0.4 vs . 1.76 +/- 0.1 ng/ml). In a two-factor ANOVA, both smoking (P < 0.01) and m icrovascular complications (P < 0.05) were independent predictors of solubl e tumor necrosis factor-<alpha> receptor-R1. Soluble tumor necrosis factor- alpha receptor levels of diabetic patients who did not smoke or without com plications were similar to those of healthy controls. In conclusion, smokin g and microvascular complications seem to exert an additive and deleterious impact on TNF-alpha activation, as reflected by levels of soluble tumor ne crosis factor-alpha receptors, in young adults with type I diabetes.