Plasma PAI-1 levels in obese children--effect of weight loss and influence of PAI-1 promoter 4G/5G genotype.

An association between an increase in plasminogen activator inhibitor type 1 (PAI-1) and obesity, and also between elevated levels of PAI-1 and the presence of PAI-1 promoter 4G allele has been described in adults and can contribute to increased risk of cardiovascular disease. It has also been suggested that in adults a decrease in adiposity has beneficial effects on the haemostatic system. However, less information is available regarding adiposity and fibrinolysis in children. The aim of the present study is to evaluate the effect of weight loss and the influence of the PAI-1 promoter 4G/5G genotype on the fibrinolytic system and lipid parameters in obese children. The clinical groups included 102 obese children and 105 controls of similar age and sex distribution. A significant decrease in fibrinolytic activity due to a significant increase in PAI-1 antigen and activity levels was observed in the obese children in comparison with the control group. In obese children, no significant differences in PAI-1 levels between the PAI-1 4G/5G genotypes were obtained. A significant correlation was observed between PAI-1 antigenic and functional levels and body mass index (BMI), as well as between PAI-1 levels and both triglyceride and insulin levels. No correlation between PAI-1 levels and either cholesterol or glucose levels was observed. After a three-month period of treatment to reduce weight, an increase in fibrinolytic activity due to a decrease in PAI- levels was observed in the obese children who had reduced their BMI in comparison with the group of obese children who did not show a decrease in their BMI. No significant differences between the two groups with respect to the variations in tissue type plasminogen activator and fibrinogen levels were obtained after three months of intervention to reduce weight. A significant correlation was observed between variations in BMI and variations in PAI-1 levels, and a significant inverse correlation was also observed between previous PAI-1 levels and variation in PAI-1 levels. Therefore, the largest decrease in PAI-1 levels was observed in the obese children with the highest previous PAI-1 levels. In conclusion, a decrease in BMI in obese children shows a favourable effect on the fibrinolytic system due to a decrease in PAI-1 levels. However, no influence of 4G/5G genotype on PAI-1 levels was observed.