Antenatal prediction of postpartum depression with blood DNA methylation biomarkers

Abstract

Postpartum depression (PPD) affects ∼10-18% of women in the general population and results in serious consequences to both the mother and offspring. We hypothesized that predisposition to PPD risk is due to an altered sensitivity to estrogen-mediated epigenetic changes that act in a cell autonomous manner detectable in the blood. We investigated estrogen-mediated epigenetic reprogramming events in the hippocampus and risk to PPD using a cross-species translational design. DNA methylation profiles were generated using methylation microarrays in a prospective sample of the blood from the antenatal period of pregnant mood disorder patients who would and would not develop depression postpartum. These profiles were cross-referenced with syntenic locations exhibiting hippocampal DNA methylation changes in the mouse responsive to long-term treatment with 17β-estradiol (E2). DNA methylation associated with PPD risk correlated significantly with E2-induced DNA methylation change, suggesting an enhanced sensitivity to estrogen-based DNA methylation reprogramming exists in those at risk for PPD. Using the combined mouse and human data, we identified two biomarker loci at the HP1BP3 and TTC9B genes that predicted PPD with an area under the receiver operator characteristic (ROC) curve (area under the curve (AUC)) of 0.87 in antenatally euthymic women and 0.12 in a replication sample of antenatally depressed women. Incorporation of blood count data into the model accounted for the discrepancy and produced an AUC of 0.96 across both prepartum depressed and euthymic women. Pathway analyses demonstrated that DNA methylation patterns related to hippocampal synaptic plasticity may be of etiological importance to PPD.

Conflict of interest statement

CONFLICT OF INTEREST

ZK, JP and TDG are coinventors listed on a patent application for DNA methylation at biomarker loci related to PPD. The remaining authors declare no conflict of interest.

Figures

Figure 1.

Estradiol (E2)-mediated DNA methylation change is associated with postpartum depression (PPD) risk. (a) Volcano plot depicting the difference in DNA methylation between women who suffered PPD vs those who did not (x axis) against the negative natural log of the P-value of association between groups (y axis). (b) A volcano plot depicting DNA methylation differences between the ovariectomy (OVX) and OVX+E2 groups per DMR (x axis) and the—natural log of the P-value for each comparison. Horizontal red lines depict the significance of threshold of 5%. (c) Scatter plot of the –log of the P-value of association to discovery sample PPD status and the effect size E2-mediated DNA methylation change at 103 overlapping loci nominally significant in both humans and mice. (d) Scatter plot of the difference between PPD and non-PPD women in the discovery sample (y axis) as a function of that in the replication sample (x axis).

Figure 2.

Validation of biomarker loci. Boxplots of the percentage of DNA methylation in the non-postpartum depression (PPD) and PPD groups for HP1BP3 microarray (a) and pyrosequencing (b) and TTC9B microarray (e) and pyrosequencing (f) values. Scatter plots of the % DNA methylation difference between PPD minus non-PPD samples in the prepartum euthymic sample obtained by pyrosequencing (y axis) and microarray (x axis) is depicted for HP1BP3 (c) and TTC9B (g). Boxplots of the percentage of DNA methylation in the non-PPD and PPD groups for HP1BP3 pyrosequencing (d) and pyrosequencing (h) values obtained from the independent replication cohort of prepartum depressed women.

Figure 3.

Cell proportion and biomarker DNA methylation predict postpartum depression (PPD). (a) Boxplot of the ratio of monocyte percentage over the sum of T-cell, B-cell and granulocyte percentages as a function of prepartum depression status and PPD diagnosis. (b) Boxplot of the HP1BP3 DNA methylation percentage as a function of prepartum depression status and PPD diagnosis. (c) Scatterplot of the ratio of monocyte percentage over the sum of white blood cell and monocyte percentages as a function of the HP1BP3 DNA methylation percentage. (d) Receiver operator characteristic (ROC) curve of the sensitivity (y axis) vs specificity (x axis) of PPD prediction from the linear model of the HP1BP3 DNA methylation and cell-type ratio interaction, with TTC9B DNA methylation as a covariate. The solid line represents the ROC curve from the proxy-based cell proportion measurement and the dashed line represents that of the complete blood count-derived subsample.