Urinary prostasin excretion is associated with adiposity in nonhypertensive African-American adolescents

Background: Metabolic abnormalities in obesity can overstimulate the renal epithelial sodium channel (ENaC) and subsequently lead to blood pressure (BP) elevation. Prostasin, a membrane-bound/secretive serine protease, is thought to activate ENaC via the proteolytic cleavage of the channel. Our specific aim was to explore whether there is a relationship between adiposity and urinary prostasin excretion at the population level. Methods: In 271 African-American adolescents, urinary prostasin concentrations were determined by enzyme-linked immunosorbent assay and normalized by urinary creatinine. Results: Urinary prostasin excretion increased in the overweight/obese group ( n = 110, 38.2 ± 4.0 ng/mg) vs. the normal-weight group ( n = 161, 20.7 ± 1.2 ng/mg, P = 0.03). Urinary prostasin excretion was significantly correlated with BMI percentiles ( r = 0.14, P = 0.02), waist circumference ( r = 0.13, P = 0.05), total body fat mass ( r = 0.20, P < 0.01), and percentage body fat ( r = 0.23, P < 0.01). Urinary prostasin excretion was also correlated with plasma aldosterone ( r = 0.11, P = 0.05) and systolic BP (SBP; r = 0.15, P = 0.02), but the significances disappeared after adjustment of any of the adiposity variables. Conclusion: Our data for the first time suggest that adiposity plays a role in urinary prostasin excretion, and its associations with aldosterone and BP appear to be modulated by adiposity. Whether urinary prostasin excretion is a biomarker/mechanism underlying obesity-related hypertension deserves further investigations.