Sex-dimorphic pathways in the associations between maternal trait anxiety, infant BDNF methylation, and negative emotionality.

Maternal antenatal anxiety is an emerging risk factor for child emotional development. Both sex and epigenetic mechanisms, such as DNA methylation, may contribute to the embedding of maternal distress into emotional outcomes. Here, we investigated sex-dependent patterns in the association between antenatal maternal trait anxiety, methylation of the brain-derived neurotrophic factor gene (BDNF DNAm), and infant negative emotionality (NE). Mother-infant dyads (N = 276) were recruited at delivery. Maternal trait anxiety, as a marker of antenatal chronic stress exposure, was assessed soon after delivery using the Stait-Trait Anxiety Inventory (STAI-Y). Infants' BDNF DNAm at birth was assessed in 11 CpG sites in buccal cells whereas infants' NE was assessed at 3 (N = 225) and 6 months (N = 189) using the Infant Behavior Questionnaire-Revised (IBQ-R). Hierarchical linear analyses showed that higher maternal antenatal anxiety was associated with greater 6-month-olds' NE. Furthermore, maternal antenatal anxiety predicted greater infants' BDNF DNAm in five CpG sites in males but not in females. Higher methylation at these sites was associated with greater 3-to-6-month NE increase, independently of infants' sex. Maternal antenatal anxiety emerged as a risk factor for infant's NE. BDNF DNAm might mediate this effect in males. These results may inform the development of strategies to promote mothers and infants' emotional well-being.

Sex-dependent association between variability in infants' OXTR methylation at birth and negative affectivity at 3 months.

BACKGROUND: Sex-specific differences in DNA methylation of the oxytocin receptor gene (OXTR) have been shown in adults and are related to several mental disorders. Negative affectivity early in life is a trans-diagnostic risk marker of later psychopathology and is partly under genetic control. However, sex-specific variations in OXTR methylation (OXTRm) in infants and their associations with negative affectivity are still unknown. AIMS: Here, we explored sex differences in the association between infant OXTRm at birth and negative affectivity at 3 months of age. METHODS: Infants and their mothers (N = 224) were recruited at delivery. Infants' methylation status was assessed in 13 CpG sites within the OXTR gene intron 1 region (chr3: 8810654-8810919) in buccal cells at birth while 3-month-old infants' negative affectivity was assessed by mothers using a well-validated temperament questionnaire. RESULTS: OXTRm at 12 CpG sites was higher in females than in males. Moreover, higher infants' OXTRm at 6 specific CpG sites was associated with greater negative affectivity in males, but not in females. CONCLUSIONS: These results provide new insights into the role of sex-dependent epigenetic mechanisms linking OXTRm with early infants' emotional development. Understanding the degree to which epigenetic processes relate to early temperamental variations may help inform the etiology of later childhood psychopathological outcomes.

Maternal and infant NR3C1 and SLC6A4 epigenetic signatures of the COVID-19 pandemic lockdown: when timing matters.

Stress exposure during pregnancy is critically linked with maternal mental health and child development. The effects might involve altered patterns of DNA methylation in specific stress-related genes (i.e., glucocorticoid receptor gene, NR3C1, and serotonin transporter gene, SLC6A4) and might be moderated by the gestational timing of stress exposure. In this study, we report on NR3C1 and SLC6A4 methylation status in Italian mothers and infants who were exposed to the COVID-19 pandemic lockdown during different trimesters of pregnancy. From May 2020 to February 2021, 283 mother-infant dyads were enrolled at delivery. Within 24 h from delivery, buccal cells were collected to assess NR3C1 (44 CpG sites) and SLC6A4 (13 CpG sites) methylation status. Principal component (PC) analyses were used to reduce methylation data dimension to one PC per maternal and infant gene methylation. Mother-infant dyads were split into three groups based on the pregnancy trimester (first, second, third), during which they were exposed to the COVID-19 lockdown. Mothers and infants who were exposed to the lockdown during the first trimester of pregnancy had lower NR3C1 and SLC6A4 methylation when compared to counterparts exposed during the second or third trimesters. The effect remained significant after controlling for confounders. Women who were pregnant during the pandemic and their infants might present altered epigenetic biomarkers of stress-related genes. As these epigenetic marks have been previously linked with a heightened risk of maternal psychiatric problems and less-than-optimal child development, mothers and infants should be adequately monitored for psychological health during and after the pandemic.

Is Brain-Derived Neurotropic Factor Methylation Involved in the Association Between Prenatal Stress and Maternal Postnatal Anxiety During the COVID-19 Pandemic?

Background: The COVID-19 pandemic is a collective trauma that may expose susceptible individuals to high levels of stress. Pregnant women represent a high-risk population, considering that pregnancy is a period of heightened neuroplasticity and susceptibility to stress through epigenetic mechanisms. Previous studies showed that the methylation status of the BDNF gene is linked with prenatal stress exposure. The goals of this study were (a) to assess the association between pandemic-related stress and postnatal anxiety and (b) to investigate the potential role of maternal BDNF methylation as a significant mediator of this association. Methods: In the present study, we report data on the association among pandemic-related stress during pregnancy, maternal BDNF methylation, and postnatal anxiety symptoms. Pandemic-related stress and postnatal anxiety were assessed through self-report instruments. BDNF methylation was estimated in 11 CpG sites in DNA from mothers' buccal cells. Complete data were available from 108 mothers. Results: Results showed that pandemic-related stress was associated with an increased risk of postnatal anxiety, r = 0.20, p < 0.05. CpG-specific BDNF methylation was significantly associated with both prenatal pandemic-related stress, r = 0.21, p < 0.05, and postnatal maternal anxious symptoms, r = 0.25, p = 0.01. Moreover, a complete mediation by the BDNF CpG6 methylation emerged between pandemic-related stress during pregnancy and postnatal maternal anxiety, ACME = 0.66, p < 0.05. Conclusion: These findings suggest that BDNF epigenetic regulation by pandemic-related stress might contribute to increase the risk of anxiety in mothers. Policymakers should prioritize the promotion of health and wellbeing in pregnant women and mothers during the present healthcare emergency.

Hidden pandemic: COVID-19-related stress, SLC6A4 methylation, and infants' temperament at 3 months.

The COVID-19 pandemic represents a collective trauma that may have enduring stress effects during sensitive periods, such as pregnancy. Prenatal stress may result in epigenetic signatures of stress-related genes (e.g., the serotonin transporter gene, SLC6A4) that may in turn influence infants' behavioral development. In April 2020, we launched a longitudinal cohort study to assess the behavioral and epigenetic vestiges of COVID-19-related prenatal stress exposure in mothers and infants. COVID-19-related prenatal stress was retrospectively assessed at birth. SLC6A4 methylation was assessed in thirteen CpG sites in mothers and infants' buccal cells. Infants' temperament was assessed at 3-month-age. Complete data were available from 108 mother-infant dyads. Greater COVID-19-related prenatal stress was significantly associated with higher infants' SLC6A4 methylation in seven CpG sites. SLC6A4 methylation at these sites predicted infants' temperament at 3 months.

The MRX complex regulates Exo1 resection activity by altering DNA end structure.

Homologous recombination is triggered by nucleolytic degradation (resection) of DNA double-strand breaks (DSBs). DSB resection requires the Mre11-Rad50-Xrs2 (MRX) complex, which promotes the activity of Exo1 nuclease through a poorly understood mechanism. Here, we describe the Mre11-R10T mutant variant that accelerates DSB resection compared to wild-type Mre11 by potentiating Exo1-mediated processing. This increased Exo1 resection activity leads to a decreased association of the Ku complex to DSBs and an enhanced DSB resection in G1, indicating that Exo1 has a direct function in preventing Ku association with DSBs. Molecular dynamics simulations show that rotation of the Mre11 capping domains is able to induce unwinding of double-strand DNA (dsDNA). The R10T substitution causes altered orientation of the Mre11 capping domain that leads to persistent melting of the dsDNA end. We propose that MRX creates a specific DNA end structure that promotes Exo1 resection activity by facilitating the persistence of this nuclease on the DSB ends, uncovering a novel MRX function in DSB resection.