Sapropterin Treatment Prevents Congenital Heart Defects Induced by Pregestational Diabetes Mellitus in Mice

Abstract

Background Tetrahydrobiopterin is a cofactor of endothelial NO synthase ( eNOS ), which is critical to embryonic heart development. We aimed to study the effects of sapropterin (Kuvan), an orally active synthetic form of tetrahydrobiopterin on eNOS uncoupling and congenital heart defects ( CHD s) induced by pregestational diabetes mellitus in mice. Methods and Results Adult female mice were induced to pregestational diabetes mellitus by streptozotocin and bred with normal male mice to produce offspring. Pregnant mice were treated with sapropterin or vehicle during gestation. CHD s were identified by histological analysis. Cell proliferation, eNOS dimerization, and reactive oxygen species production were assessed in the fetal heart. Pregestational diabetes mellitus results in a spectrum of CHD s in their offspring. Oral treatment with sapropterin in the diabetic dams significantly decreased the incidence of CHD s from 59% to 27%, and major abnormalities, such as atrioventricular septal defect and double‐outlet right ventricle, were absent in the sapropterin‐treated group. Lineage tracing reveals that pregestational diabetes mellitus results in decreased commitment of second heart field progenitors to the outflow tract, endocardial cushions, and ventricular myocardium of the fetal heart. Notably, decreased cell proliferation and cardiac transcription factor expression induced by maternal diabetes mellitus were normalized with sapropterin treatment. Furthermore, sapropterin administration in the diabetic dams increased eNOS dimerization and lowered reactive oxygen species levels in the fetal heart. Conclusions Sapropterin treatment in the diabetic mothers improves eNOS coupling, increases cell proliferation, and prevents the development of CHD s in the offspring. Thus, sapropterin may have therapeutic potential in preventing CHD s in pregestational diabetes mellitus.

Say NO to ROS: Their Roles in Embryonic Heart Development and Pathogenesis of Congenital Heart Defects in Maternal Diabetes

“…Further, impaired cardiac gene expression and cell proliferation induced by maternal diabetes were normalized with sapropterin treatment. Most strikingly, the incidence of CHDs was lowered from 59% to 27%, and major abnormalities such as AVSD and DORV were absent in the sapropterin-treated group [15]. The study shows a pivotal role of eNOS uncoupling in the pathogenesis of CHDs in diabetic pregnancies (Table 1).…”

“…Furthermore, lower NO levels are associated with higher Jarid2 expression and its enhanced interaction with the Notch1 locus, leading to decreased Notch1 expression and a higher incidence of VSDs in offspring of maternal diabetes [14]. Notably, pregestational diabetes lowers fetal BH4 levels, and induces eNOS uncoupling, elevated superoxide generation, as well as altered cardiac gene expression of Gata4 , Gata5 , Nkx2.5 , Tbx5 , and Bmp10 in the fetal heart [15]. Moreover, mRNA levels of GTPCH1 and DHFR, enzymes involved in BH4 synthesis, were also significantly reduced at E12.5 in the fetal heart of offspring from diabetic dams, compared with control [15].…”

“…Notably, pregestational diabetes lowers fetal BH4 levels, and induces eNOS uncoupling, elevated superoxide generation, as well as altered cardiac gene expression of Gata4 , Gata5 , Nkx2.5 , Tbx5 , and Bmp10 in the fetal heart [15]. Moreover, mRNA levels of GTPCH1 and DHFR, enzymes involved in BH4 synthesis, were also significantly reduced at E12.5 in the fetal heart of offspring from diabetic dams, compared with control [15]. To elucidate the role of eNOS uncoupling in the pathogenesis of CHDs, diabetic dams were treated with sapropterin (Kuvan ® ), an orally active synthetic form of BH4.…”

“…This depletion of pancreatic β-cells and thereby insulin supply recapitulates T1D in humans. Animal studies analyzing heart development in this model of pregestational maternal diabetes indicate that reactive oxygen species (ROS) are critical players in mediating maladaptive heart development, leading to CHDs [13,14,15,16,17,18,19,20,21,22,23,24,25]. Oxidative stress, brought on by hyperglycemia, is not conducive to the development of cardiac progenitors as it results in the oxidation and inactivation of many molecules and enzymes necessary for cardiogenesis.…”

Pregestational diabetes in pregnancy: Complications, management, surveillance, and mechanisms of disease—A review

“…22,23 In mice, the occurrence of fetal malformations in diabetic pregnancy can be reduced by reducing oxidative stress (eg, the antioxidant N-Acetylcysteine) and increasing nitric oxide production (eg, the tetrahydrobiopterin Sapropterin which improves eNOS function). 24,25 However, clinical trials in human pregnancy have shown unexpected adverse outcomes including an increase in the incidence of intrauterine growth restriction. 26 The human trials were not in women with diabetes, and were not powered for uncommon congenital anomalies.…”