Exercise-Induced Leukocyte Response and Changes in VEGF mRNA Expression in Healthy and Type 1 Diabetic Children.

The health effects of exercise depend on a complex equilibrium of often opposing mechanisms that may become altered in pathological states. In type 1 diabetes (T1DM), leukocyte activity dysregulation strongly correlates with diabetic vascular complications; it may therefore be important to identify alterations in exercise-induced leukocyte responses (total/fractional WBC counts, changes in leukocyte gene expression of immuno-modulatory factors). Little is known, however, about these responses, particularly in children. This study therefore investigated exercise-induced changes in leukocyte counts and mRNA expression of IL-6, IL- 10, VEGF, COX2, CD11a and HSP70 in control (n = 24, 14.1 ± 0.7 yrs, 8M/16F) and T1DM (n = 13, 13.3 ± 0.5 yrs, 8M/5F) children. Exercise consisted of 10 bouts of 2-min cycling at 80% VO2max separated by 1-min rest. For at least 90 min prior to and during exercise, euglycemia (80-110 mg/dL) was maintained for T1DM. Blood was drawn at baseline, end-exercise and 30-min post. mRNA expression was calculated as ratios of individual mRNAs and mRNA of the housekeeping protein β-actin to normalize for leukocytosis. The exercise-induced increase in WBC concentrations, observed in controls, was well preserved in T1DM. By 30-min post exercise, neutrophil and monocyte counts returned to baseline in both groups, while lymphocytes dipped below baseline. At end-exercise, WBC VEGF mRNA expression was significantly greater in T1DM than controls (p=0.041), while no difference was measured for other tested genes. Our data show that while the overall leukocytic response to exercise is well preserved in T1DM children, a significant alteration was present in the WBC mRNA expression of at least one major immune-modulator, VEGF, implicated in the pathological thickening of extracellular matrix causing reduced arterial perfusion. Our observations underscore the need for a deeper understanding of all aspects of exercise adaptation in populations at increased risk of long-term cardiovascular complications, including T1DM children. [ABSTRACT FROM AUTHOR]