Low Levels of Indoleamine 2, 3 dioxygenase (IDO) in Pregnancy are Associated with Increased Pulse Wave Velocity in Preeclampsia
Preeclampsia is a disorder of late pregnancy that involves an increase in vascular dysfunction. In previous studies, preeclampsia has been linked to low levels of Indoleamine 2,3 dioxygenase (IDO) which provides a link between the immune dysregulation and oxidative endothelial damage that result in poor vascular function in preeclampsia. Because of this, we hypothesized women with low IDO activity levels early in pregnancy would go on to have the poor vascular function. In this nested case-control study, clinical, demographic, and assay data from a cohort of pregnant women recruited to longitudinal studies measuring noninvasive vascular function and circulating factors were utilized. IDO activity was measured using a colorimetric assay for women during all three trimesters of pregnancy. Pulse wave velocity (PWV), a measure of vascular function, was also measured throughout gestation. Low IDO activity was associated with a significant increase in PWV in both the second and third trimesters indicating vascular dysfunction. This association was no longer statistically significant when using linear regression to control for significant cofounders such as BMI and chronic hypertension in the second trimester. In the third trimester, low IDO activity was significantly associated with increasing PWV. These data suggest that although IDO activity may not be part of the causal pathway for vascular dysfunction, it may still be implicated in the vascular dysfunction in diseases like preeclampsia.