Maternal stress, placental 11β-hydroxysteroid dehydrogenase type 2, and infant HPA axis development in humans: Psychosocial and physiological pathways

Introduction: Prenatal stress is known to influence fetal hypothalamic-pituitary-adrenal axis (HPA axis) development. Placental 11 beta-hydroxysteroid dehydrogenase type 2 (HSD11B2) is a central gene in this pathway, but little is known about what influences its functioning. We assess how maternal distress influences HSD11B2 functioning, and how HSD11B2 in turn, is associated with infant HPA axis development. Methods: Data come from 24 mother-infant dyads on the Galapagos Islands. Using adjusted linear regression models, we assess the effects of maternal psychosocial (stress and depressive symptoms, measured by the Perceived Stress Scale and the Patient Health Questionnaire-8, respectively) and physiological (HPA axis dys-regulation) distress during pregnancy on HSD11B2 methylation and expression and then test how these HSD11B2 measures influence infant HPA axis development. Results: Maternal HPA axis dysregulation during pregnancy is associated with lower placental HSD11B2 expression, which is associated with an exaggerated cortisol reactivity in infants. Sex-specific analyses revealed that maternal depressive symptoms may influence the functioning of placental HSD11B2 differently in girls (n = 11, 46%) than in boys (n = 13, 54%), though the sample size was small. Discussion: These results support a disrupted adaptive framework, in which the ability to upregulate HSD11B2 expression in response to acute stress diminishes as maternal stress becomes chronic. In this model, chronic stress may exhaust the protective mechanism of HSD11B2, leaving the infant vulnerable to high levels of maternal cortisol, which could injure the fetal HPA axis and disrupt long-term neurobehavioral and metabolic development. While larger studies will be needed to confirm these findings, this study offers exploratory results on the effects of maternal distress on both HSD11B2 methylation and expression and the effect of HSD11B2 on offspring HPA axis development.