Pregnancy complications affect kynurenine pathway metabolite concentrations in umbilical cord blood

Tryptophan and its kynurenine pathway (KP) metabolites play key roles in modulating the immune system and vasculature, and exhibit both pro- and antioxidant properties, making them crucial for a healthy pregnancy and fetal development. Disruptions in the KP may impact both prenatal and postnatal health, however, data on fetal KP metabolite concentrations and their alterations in pregnancy-related disorders remain scarce. This study aims to investigate the association between pregnancy complications and KP metabolite concentrations in umbilical cord blood.

Pregnancies complicated by preeclampsia (n = 40), fetal growth restriction (FGR, n = 33), pregestational diabetes mellitus (DM, n = 42), gestational diabetes mellitus (GDM, n = 61), and amniotic infection syndrome (AIS, n = 47) were included, along with 410 controls matched in a 1:2 ratio using Mahalanobis nearest-neighbor matching from a prospective birth cohort study. Tryptophan, kynurenine, anthranilic acid, 3-hydroxykynurenine, 3-hydroxyanthranilic acid, kynurenic acid, xanthurenic acid, quinolinic acid, picolinic acid, and nicotinic acid were measured in umbilical cord blood using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Differences in metabolite concentrations were analyzed using unpaired t-tests and linear regression models to control for potential confounders.

Tryptophan concentrations were decreased in cases of preeclampsia and DM. We identified elevated levels of 3-hydroxykynurenine in preeclampsia, kynurenine in GDM, and nicotinic acid in both FGR and DM. Quinolinic acid levels were also higher in preeclampsia and GDM, although this was not significant after adjusting for confounding variables. We observed no changes in KP metabolites in AIS.

This study identified distinct alterations in umbilical cord blood KP metabolite concentrations in pregnancies with preeclampsia, FGR, DM, and GDM, but not AIS. This suggests differential regulation and activation of the KP depending on the pregnancy disorder. Such changes may influence maternal and infant health and could play a role in fetal programming, with potential long-term effects on child development and health.