Allison A. Appleton

The roles of DNA methylation of NR3C1 and 11β-HSD2 and exposure to maternal mood disorder in utero on newborn neurobehavior

Exposure to maternal mood disorder in utero may program infant neurobehavior via DNA methylation of the glucocorticoid receptor (NR3C1) and 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD-2), two placental genes that have been implicated in perturbations of the hypothalamic pituitary adrenocortical (HPA) axis. We tested the relations among prenatal exposure to maternal depression or anxiety, methylation of exon 1F of NR3C1 and 11β-HSD-2, and newborn neurobehavior. Controlling for relevant covariates, infants whose mothers reported depression during pregnancy and showed greater methylation of placental NR3C1 CpG2 had poorer self-regulation, more hypotonia, and more lethargy than infants whose mothers did not report depression. On the other hand, infants whose mothers reported anxiety during pregnancy and showed greater methylation of placental 11β-HSD-2 CpG4 were more hypotonic compared with infants of mothers who did not report anxiety during pregnancy. Our results support the fetal programming hypothesis and suggest that fetal adjustments to cues from the intrauterine environment, in this case an environment that could be characterized by increased exposure to maternal cortisol, may lead to poor neurodevelopmental outcomes.

A Heartfelt Response: Oxytocin Effects on Response to Social Stress in Men and Women

BACKGROUND Animal research indicates that oxytocin is involved in social behavior, stress regulation, and positive physiologic adaptation. This study examines whether oxytocin enhances adaptive responses to social stress and compares effects between men and women. METHODS Hypotheses were tested with a placebo-controlled, double-blind experiment. Social stress was induced. Changes in cardiovascular reactivity, affect, and behavior were assessed. RESULTS Participants given oxytocin, relative to placebo, responded to social stress with a challenge orientation characterized by a benign pattern of cardiovascular reactivity. Gender differences emerged. Men given oxytocin reported less negative affect and had greater vagal rebound, while women given oxytocin reported more anger and had better math performance following social stress. DISCUSSION Findings indicate oxytocin stimulates an approach-oriented cardiovascular profile during social stress, suggesting mechanisms by which oxytocin might improve physical health. However, before considering oxytocin as therapeutic or uniformly enhancing health, greater understanding of possible gender differences in effects is needed.

Divergent associations of adaptive and maladaptive emotion regulation strategies with inflammation.

OBJECTIVE Recent work suggests effective emotion regulation may protect against risk of developing coronary heart disease (CHD), but the mechanisms remain unknown. Strategies for regulating emotions vary in how effectively they mitigate potentially toxic effects of stressful life experiences, and therefore may be differentially associated with CHD risk. In this study, we examined the emotion regulation strategies of reappraisal and suppression in relation to inflammation, a biological state associated with both stress and CHD. We hypothesized that suppression would be associated with elevated inflammation and reappraisal would be associated with lower levels of inflammation. METHODS We studied adult offspring (n = 379; mean age = 42.2 years) of Collaborative Perinatal Project participants, a national cohort of pregnant women enrolled in 1959-1966. Validated measures of two emotion regulation strategies were examined: reappraisal and suppression. Inflammation was measured as plasma C-reactive protein (CRP) levels. We fit multiple linear regression models predicting CRP while controlling for demographic, socioeconomic, and health factors, including depressive symptoms, measured across the life course. RESULTS A 1 standard deviation increase in reappraisal was associated with significantly lower CRP (b = -0.18, SE = 0.06, p < .01) controlling for demographics. This relation was somewhat attenuated in life course models, with adulthood body mass index partially explaining the association. A 1 standard deviation increase in suppression was associated with significantly higher CRP (b = 0.21, SE = 0.05, p < .001), and this association was not substantively attenuated with further covariate adjustment. CONCLUSION Adaptive emotion regulation was associated with lower levels of inflammation and maladaptive emotion regulation was associated with higher levels of inflammation. If these associations are confirmed by prospective and experimental studies, such evidence may provide insight into novel targets for interventions to promote health and reduce cardiovascular risk.

Early origins of inflammation: An examination of prenatal and childhood social adversity in a prospective cohort study

BACKGROUND Children exposed to social adversity carry a greater risk of poor physical and mental health into adulthood. This increased risk is thought to be due, in part, to inflammatory processes associated with early adversity that contribute to the etiology of many adult illnesses. The current study asks whether aspects of the prenatal social environment are associated with levels of inflammation in adulthood, and whether prenatal and childhood adversity both contribute to adult inflammation. METHODS We examined associations of prenatal and childhood adversity assessed through direct interviews of participants in the Collaborative Perinatal Project between 1959 and 1974 with blood levels of C-reactive protein in 355 offspring interviewed in adulthood (mean age=42.2 years). Linear and quantile regression models were used to estimate the effects of prenatal adversity and childhood adversity on adult inflammation, adjusting for age, sex, and race and other potential confounders. RESULTS In separate linear regression models, high levels of prenatal and childhood adversity were associated with higher CRP in adulthood. When prenatal and childhood adversity were analyzed together, our results support the presence of an effect of prenatal adversity on (log) CRP level in adulthood (β=0.73, 95% CI: 0.26, 1.20) that is independent of childhood adversity and potential confounding factors including maternal health conditions reported during pregnancy. Supplemental analyses revealed similar findings using quantile regression models and logistic regression models that used a clinically-relevant CRP threshold (>3mg/L). In a fully-adjusted model that included childhood adversity, high prenatal adversity was associated with a 3-fold elevated odds (95% CI: 1.15, 8.02) of having a CRP level in adulthood that indicates high risk of cardiovascular disease. CONCLUSIONS Social adversity during the prenatal period is a risk factor for elevated inflammation in adulthood independent of adversities during childhood. This evidence is consistent with studies demonstrating that adverse exposures in the maternal environment during gestation have lasting effects on development of the immune system. If these results reflect causal associations, they suggest that interventions to improve the social and environmental conditions of pregnancy would promote health over the life course. It remains necessary to identify the mechanisms that link maternal conditions during pregnancy to the development of fetal immune and other systems involved in adaptation to environmental stressors.

Sex-specific associations between placental leptin promoter DNA methylation and infant neurobehavior

BACKGROUND Leptin (LEP) is a hormone central for energy homeostasis and has been implicated in neurodevelopment. This adipokine is produced by the placenta and is epigenetically regulated by promoter DNA methylation. Recent evidence has suggested a role for LEP in behavioral development. In this study, we investigated associations between profiles of human newborn neurobehavior and placental LEP DNA methylation. METHODS We determined LEP promoter methylation in 444 placental samples from healthy term infants and measured LEP gene expression in a random subset of these samples. Infant neurobehavior was assessed with the NICU Network Neurobehavioral Scales (NNNS) and we examined the relationship between LEP promoter methylation and profiles of infant neurobehavior derived from these scores generated using a hierarchical model-based clustering method. RESULTS LEP methylation is negatively correlated with gene expression only in placentas from male infants (r=-0.6, P=0.006). A 10% increase in LEP DNA methylation was associated with membership in a profile of infant neurobehavior marked by increased lethargy and hypotonicity (OR=1.9; 95% CI: 1.07-3.4), and consistently with reduced risk of membership in a profile characterized by decreased lethargy and hypotonicity (OR=0.54; 95% CI: 0.3-0.94) only in male infants (n=223). No statistically significant associations were observed amongst female infants. DISCUSSION These results suggest that increased placental LEP DNA methylation, related to reduced expression, may play a role in human newborn neurodevelopment, particularly in reactivity to various stimuli, but that these effects may be sexually dimorphic.

Childhood Social Disadvantage, Cardiometabolic Risk, and Chronic Disease in Adulthood

Adverse social environments in early life are hypothesized to become biologically embedded during the first few years of life, with potentially far-reaching implications for health across the life course. Using prospective data from a subset of a US birth cohort, the Collaborative Perinatal Project, started in 1959-1966 (n = 566), we examined associations of social disadvantage assessed in childhood with cardiometabolic function and chronic disease status more than 40 years later (in 2005-2007). Social disadvantage was measured with an index that combined information on adverse socioeconomic and family stability factors experienced between birth and age 7 years. Cardiometabolic risk (CMR) was assessed by combining information from 8 CMR biomarkers; an index of chronic disease status was derived by assessing 8 chronic diseases. Poisson models were used to investigate associations between social disadvantage and CMR or chronic disease scores while adjusting for childhood covariates and potential pathway variables. A high level of social disadvantage was significantly associated with both higher CMR (incident rate ratio = 1.69, 95% confidence interval: 1.19, 2.39) and with a higher number of chronic diseases (incident rate ratio = 1.39, 95% confidence interval: 1.00, 1.92) in minimally adjusted models. Associations with CMR persisted even after accounting for childhood and adult covariates.

A Prospective Study of Positive Early Life Psychosocial Factors and Favorable Cardiovascular Risk in Adulthood

Background— The American Heart Association’s national goals for cardiovascular health promotion emphasize that cardiovascular risk originates early in life, but little is known about childhood factors that may increase the likelihood of having a favorable cardiovascular risk (FCR) in adulthood. We examined the prospective association between positive childhood factors and the likelihood of midlife FCR. We also considered pathways through which childhood factors may influence FCR. Methods and Results— We studied 415 adults (mean age=42.2 years) of the Collaborative Perinatal Project, a national cohort initiated in 1959 to 1966. We examined 3 positive childhood factors assessed at age 7 years: attention regulation (ability to stay focused), cognitive ability, and positive home environment. Of these adults, 10.6% had FCR in midlife. Adjusting for demographics and childhood cardiovascular health, a 1-unit increase in childhood attention regulation, cognitive ability, and positive home environment was associated with 2.4 (95% confidence interval, 1.1–4.7), 1.8 (95% confidence interval, 1.1–2.9), and 1.3 (95% confidence interval, 1.1–1.6) higher respective odds of having midlife FCR. The association with childhood attention regulation was maintained when accounting for adulthood factors; education and diet in part explained the associations with childhood cognitive ability and home environment. The effect of each attribute was additive as those with high levels of each childhood factor had 4.3 higher odds (95% confidence interval, 1.01–18.2) of midlife FCR in comparison with those low in all factors. Conclusions— Positive childhood psychosocial factors may promote healthy adult cardiovascular functioning. Primordial prevention efforts aimed at preventing the development of cardiovascular risk should consider building on childhood psychosocial resources.

Placental HTR2A methylation is associated with infant neurobehavioral outcomes

The serotonin receptor, HTR2A, exhibits placental expression and function and can be controlled through DNA methylation. The relationship between methylation of HTR2A in the placenta and neurodevelopmental outcomes, evaluated using the NICU Network Neurobehavioral Scales (NNNS), was assessed in newborn infants (n = 444). HTR2A methylation was significantly higher in males and marginally higher in infants whose mothers reported tobacco use during pregnancy. Controlling for confounding variables, HTR2A methylation was negatively associated with infant quality of movement (p = 0.05) and positively associated with infant attention (p = 0.0001). These results suggest that methylation of the HTR2A gene can be biologically and environmentally modulated and is associated with key measures of neurodevelopment.

Examining the joint contribution of placental NR3C1 and HSD11B2 methylation for infant neurobehavior

Infant neurobehavior, a potential sentinel of future mental and behavioral morbidity characterized in part by reflex symmetry, excitability and habituation to stimuli, is influenced by aspects of the intrauterine environment partially through epigenetic alterations of genes involved in the stress response. DNA methylation of two related cortisol response genes, the glucocorticoid receptor (NR3C1), a nuclear receptor to which cortisol binds, and 11-beta hydroxysteroid dehydrogenase (HSD11B2), the enzyme responsible for conversion of cortisol into inactive cortisone, independently associate with infant neurobehavior. Although these factors are part of a common cortisol regulation pathway, the combined effect of DNA methylation of these factors on infant neurobehavior has not been characterized. Therefore, we conducted an examination of the joint contribution of NR3C1 and HSD11B2 DNA methylation on infant neurobehavior. Among 372 healthy term newborns, we tested the interaction between placental NR3C1 and HSD11B2 DNA methylation in association with neurobehavior as assessed with the validated NICU Network Neurobehavioral Scales. Controlling for confounders, interactions between DNA methylation of these genes were detected for distinct domains of neurobehavior (habituation, excitability, asymmetrical reflexes). Moreover, different patterns of DNA methylation across the cortisol regulation pathway associated with different neurobehavioral phenotypes. Those with low NR3C1 methylation but high HSD11B2 methylation had lower excitability scores; those with high NR3C1 methylation but low HSD11B2 methylation had more asymmetrical reflexes; those with high DNA methylation across the entire pathway had higher habituation scores. These results suggest that epigenetic alterations across the cortisol regulation pathway may contribute to different neurobehavioral phenotypes, likely though varying degrees of glucocorticoid exposure during gestation. While the postnatal environment may continue to affect neurobehavioral risk, this study provides novel insights into the molecular basis for fetal origins of mental conditions.

The association between childhood emotional functioning and adulthood inflammation is modified by early-life socioeconomic status.

OBJECTIVE Identifying interrelationships among childhood social disadvantage, emotional functioning and adult health may help illustrate how health disparities may become embedded early in life, yet few have considered how these factors are associated. We examined whether the association of child emotional functioning and adult health risk was modified by child socioeconomic status (CSES), or whether child emotional functioning mediated the association of CSES and adult health risk. METHOD We studied 430 adult offspring (mean age 42 years) of Collaborative Perinatal Project participants, a cohort of pregnant women enrolled in 1959-1966 (Broman, Nichols, & Kennedy, 1975; Niswander & Gordon, 1972). Child emotional functioning was assessed by psychologist ratings at age 7 and included inappropriate self regulation (ISR) and distress proneness. CSES measures included parental education, household income, and parental occupation. Adult health risk was measured by the inflammatory marker C-reactive protein (CRP). Hypotheses were tested with multiple linear regression. Effect modification was evaluated via interaction terms and stratification of fully adjusted models by CSES. Mediation by child emotional functioning was evaluated via coefficient changes. RESULTS There was no evidence that child emotional functioning mediated the association of CSES and CRP. Significant interactions were observed for ISR and low income (b = 1.67, SE = 0.70, p < .05), and distress proneness and low (b = 3.14, SE = 1.47, p < .05) and middle (b = 3.52, SE = 1.46, p < .05) income. Stratified models indicated that associations of child emotion with CRP varied significantly by level of parental education, household income and occupation. CONCLUSION The highest levels of adult inflammation were observed among those with childhood emotional problems who were also exposed to low socioeconomic status as children. This study suggests adulthood disparities in CRP may have developmental origins in childhood adversity.