Background: Hypospadias in boys may be associated with a lack of androgen exposure during the masculinisation programming window. As testosterone has effects on the vasculature, we assessed whether boys with hypospadias show any evidence of vascular dysfunction.
Methods: Excess foreskin tissue was obtained from boys undergoing hypospadias repair (cases) or circumcision (controls) and small arteries dissected from this tissue. Vascular contractility was assessed by wire myography in response to U46619 (thromboxane A2 analogue). Vascular smooth muscle cells (VSMCs) were cultured and generation of reactive oxygen species (ROS) was measured by amplex red and chemiluminescence. NADPH oxidase (Nox) mRNA expression was measured by qPCR.
Results: 19 cases and 22 age-matched controls were enrolled in this study (median age 1.9 (range 1.3, 12.2) years). There were 8 (42%) cases of distal, 4 (21%) of midshaft and 7 (37%) of proximal hypospadias. Endocrine and genetic evaluation did not reveal an underlying disorder of sex development in the cases and there were no differences in clinical cardiometabolic or biochemical parameters between the cases and controls. Arteries from cases demonstrated increased constriction to U46619 compared to controls (Emax: 175.6 vs 66.3 P<0.001), an effect inhibited by the ROS scavenger N-acetylcysteine (NAC). VSMC superoxide anion (5.3 fold) production and H2O2 (3.3 fold) levels were increased in cases compared to controls (P<0.05). Expression of Nox5, a major ROS-generating oxidase in vascular cells, was increased in cases (2.6 fold, P<0.05). Exposure of vessels to testosterone increased vasoconstriction to U46619 (Emax: 66.3 to 124.6 P<0.001) in controls, but not in cases. Incubation with NAC abolished the testosterone-induced vascular effects. Vascular hypercontractility in boys with hypospadias was associated with reduced endothelium-dependent and independent vasorelaxation, compared with controls.
Conclusions: These novel data, from a unique cohort of patients, demonstrate that small arteries from boys with hypospadias exhibit increased vascular contractility and decreased vasorelaxation with associated increased Nox-derived ROS generation. The functional significance of vascular dysfunction in these boys is unclear, but may play a role in immediate surgical outcome as well as altered long-term cardiovascular risk.
27 Sep 2018 - 29 Sep 2018