Project description:We developed two novel sperm epigenetic clocks by applying Super Learner, an ensemble machine learning algorithm, to predict age from sperm EPIC array DNA methylation data via individual CpG sites and differentially methylated regions (DMRs). Overall, our cox model showed that one-year increase in our developed sperm epigenetic age (SEA) was associated with up to 15% reduction in couples time-to-pregnancy (TTP).
Project description:Study questionIs sperm epigenetic aging (SEA) associated with probability of pregnancy among couples in the general population?Summary answerWe observed a 17% lower cumulative probability at 12 months for couples with male partners in the older compared to the younger SEA categories.What is known alreadyThe strong relation between chronological age and DNA methylation profiles has enabled the estimation of biological age as epigenetic 'clock' metrics in most somatic tissue. Such clocks in male germ cells are less developed and lack clinical relevance in terms of their utility to predict reproductive outcomes.Study design, size, durationThis was a population-based prospective cohort study of couples discontinuing contraception to become pregnant recruited from 16 US counties from 2005 to 2009 and followed for up to 12 months.Participants/materials, setting, methodsSperm DNA methylation from 379 semen samples was assessed via a beadchip array. A state-of-the-art ensemble machine learning algorithm was employed to predict age from the sperm DNA methylation data. SEA was estimated from clocks derived from individual CpGs (SEACpG) and differentially methylated regions (SEADMR). Probability of pregnancy within 1 year was compared by SEA, and discrete-time proportional hazards models were used to evaluate the relations with time-to-pregnancy (TTP) with adjustment for covariates.Main results and the role of chanceOur SEACpG clock had the highest predictive performance with correlation between chronological and predicted age (r = 0.91). In adjusted discrete Cox models, SEACpG was negatively associated with TTP (fecundability odds ratios (FORs)=0.83; 95% CI: 0.76, 0.90; P = 1.2×10-5), indicating a longer TTP with advanced SEACpG. For subsequent birth outcomes, advanced SEACpG was associated with shorter gestational age (n = 192; -2.13 days; 95% CI: -3.67, -0.59; P = 0.007). Current smokers also displayed advanced SEACpG (P < 0.05). Finally, SEACpG showed a strong performance in an independent IVF cohort (n = 173; r = 0.83). SEADMR performance was comparable to SEACpG but with attenuated effect sizes.Limitations, reasons for cautionThis prospective cohort study consisted primarily of Caucasian men and women, and thus analysis of large diverse cohorts is necessary to confirm the associations between SEA and couple pregnancy success in other races/ethnicities.Wider implications of the findingsThese data suggest that our sperm epigenetic clocks may have utility as a novel biomarker to predict TTP among couples in the general population and underscore the importance of the male partner for reproductive success.Study funding/competing interest(s)This work was funded in part by grants the National Institute of Environmental Health Sciences, National Institutes of Health (R01 ES028298; PI: J.R.P. and P30 ES020957); Robert J. Sokol, MD Endowed Chair of Molecular Obstetrics and Gynecology (J.R.P.); and the Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland (Contracts N01-HD-3-3355, N01-HD-3-3356 and N01-HD-3-3358). S.L.M. was supported by the Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health. The authors declare no competing interests.Trial registration numberN/A.
Project description:Paternal exposure to environmentally-relevant Arctic contaminants induces adverse health outcomes and alters the sperm methylome over three generations.
Project description:We hypothesized that the availability of folate, a soluble B vitamin, would alter the levels of DNA methylation in spermatogenesis with consequences for the sperm epigenome and pregnancy outcomes. We fed male mice with either a folate-deficient or a folate-sufficient diet throughout life. Males fed the folate-deficient diet had offspring with increased birth defects, which included craniofacial and musculoskeletal malformations. These phenotypes corresponded to developmental genes with altered methylation in sperm. To determine if there was transmission of epigenetic effects from sires to offspring, global gene expression levels were assessed in placenta from 18.5 dpc fetuses sired by either a folate-sufficient or folate-deficient male. Gene expression was measured in placenta of 18.5 dpc fetuses sired by either a folate sufficient male (n=4 placentas from different litters and different fathers) or a folate deficient (FD) male (n=4 placentas from different litters and different fathers).
Project description:We hypothesized that the availability of folate, a soluble B vitamin, would alter the levels of DNA methylation in spermatogenesis with consequences for the sperm epigenome and pregnancy outcomes. We fed male mice with either a folate-deficient or a folate-sufficient diet throughout life. Males fed the folate-deficient diet had offspring with increased birth defects, which included craniofacial and musculoskeletal malformations. These phenotypes corresponded to developmental genes with altered methylation in sperm. To determine if there was transmission of epigenetic effects from sires to offspring, global gene expression levels were assessed in placenta from 18.5 dpc fetuses sired by either a folate-sufficient or folate-deficient male.