Stability of the human sperm DNA methylome to folic acid fortification and short-term supplementation

DNA Methylation and Non-Coding RNAs in Metabolic Disorders: Epigenetic Role of Nutrients, Dietary Patterns, and Weight Loss Interventions for Precision Nutrition

BACKGROUND

Dysregulation of epigenetic processes and abnormal epigenetic profiles are associated with various metabolic disorders. Nutrition, as an environmental factor, can induce epigenetic changes through both direct exposure and transgenerational inheritance, continuously altering gene expression and shaping the phenotype. Nutrients consumed through food or supplementation, such as vitamin B12, folate, vitamin B6, and choline, play a pivotal role in DNA methylation, a critical process for gene regulation. Additionally, there is mounting evidence that the expression of non-coding RNAs (ncRNAs) can be modulated by the intake of specific nutrients and natural compounds, thereby influencing processes involved in the onset and progression of metabolic diseases.

SUMMARY

Evidence suggests that dietary patterns, weight loss interventions, nutrients and nutritional bioactive compounds can modulate the expression of various microRNA (miRNAs) and DNA methylation levels, contributing to the development of metabolic disorders such as obesity and type 2 diabetes. Furthermore, several studies have proposed that DNA methylation and miRNA expression could serve as biomarkers for the effects of weight loss programs.

KEY MESSAGE

Despite ongoing debate regarding the effects of nutrient supplementation on DNA methylation levels and the expression of ncRNAs, certain DNA methylation marks and ncRNA expressions might predict the risk of metabolic disorders and act as biomarkers for forecasting the success of therapies within the framework of precision medicine and nutrition. The role of DNA methylation and miRNA expression as potential mediators of the effects of weight loss underscores their potential as biomarkers for the outcomes of weight loss programs. This highlights the influence of dietary patterns and weight loss interventions on the regulation of miRNA expression and DNA methylation levels, suggesting an interaction between these epigenetic factors and the body's response to weight loss.

Examining nutrition strategies to influence DNA methylation and epigenetic clocks: a systematic review of clinical trials

Nutrition has powerful impacts on our health and longevity. One of the mechanisms by which nutrition might influence our health is by inducing epigenetic modifications, modulating the molecular mechanisms that regulate aging. Observational studies have provided evidence of a relationship between nutrition and differences in DNA methylation. However, these studies are limited in that they might not provide an accurate control of the interactions between different nutrients, or between nutrition and other lifestyle behaviors. Here we systematically reviewed clinical studies examining the impact of nutrition strategies on DNA methylation. We examined clinical studies in community-dwelling adults testing the effects of nutrition interventions on i) global DNA methylation and its proxies, and ii) epigenetic clocks. We included 21 intervention studies that focused on the effects of healthy nutrition patterns, specific foods or nutrients, as well as the effect of multivitamin or multimineral supplements. In four studies on the methylation effects of healthy dietary patterns, as defined by being rich in vegetables, fruits, whole-grains, and nuts and reduced in the intake of added sugars, saturated fat, and alcohol, two of them suggested that a healthy diet, is associated with lower epigenetic age acceleration, one of them reported increases in global DNA methylation, while another one found no diet effects. Studies examining epigenetic effects of specific foods, nutrients, or mixtures of nutrients were scarce. For both folic acid and polyunsaturated fatty acids, the available independent studies produced conflicting findings. Although more evidence is still needed to draw firm conclusions, results begin to suggest that healthy dietary patterns have positive effects on DNA methylation. Additional evidence from large randomized-controlled clinical trials is needed to support the effects of healthy nutrition on the DNA methylome.

Sperm DNA methylome abnormalities occur both pre- and post-treatment in men with Hodgkin disease and testicular cancer

BACKGROUND

Combination chemotherapy has contributed to increased survival from Hodgkin disease (HD) and testicular cancer (TC). However, questions concerning the quality of spermatozoa after treatment have arisen. While studies have shown evidence of DNA damage and aneuploidy in spermatozoa years following anticancer treatment, the sperm epigenome has received little attention. Our objectives here were to determine the impact of HD and TC, as well as their treatments, on sperm DNA methylation. Semen samples were collected from community controls (CC) and from men undergoing treatment for HD or TC, both before initiation of chemotherapy and at multiple times post-treatment. Sperm DNA methylation was assessed using genome-wide and locus-specific approaches.

RESULTS

Imprinted gene methylation was not affected in the sperm of HD or TC men, before or after treatment. Prior to treatment, using Illumina HumanMethylation450 BeadChip (450 K) arrays, a subset of 500 probes was able to distinguish sperm samples from TC, HD and CC subjects; differences between groups persisted post-treatment. Comparing altered sperm methylation between HD or TC patients versus CC men, twice as many sites were affected in TC versus HD men; for both groups, the most affected CpGs were hypomethylated. For TC patients, the promoter region of GDF2 contained the largest region of differential methylation. To assess alterations in DNA methylation over time/post-chemotherapy, serial samples from individual patients were compared. With restriction landmark genome scanning and 450 K array analyses, some patients who underwent chemotherapy showed increased alterations in DNA methylation, up to 2 to 3 years post-treatment, when compared to the CC cohort. Similarly, a higher-resolution human sperm-specific assay that includes assessment of environmentally sensitive regions, or "dynamic sites," also demonstrated persistently altered sperm DNA methylation in cancer patients post-treatment and suggested preferential susceptibility of "dynamic" CpG sites.

CONCLUSIONS

Distinct sperm DNA methylation signatures were present pre-treatment in men with HD and TC and may help explain increases in birth defects reported in recent clinical studies. Epigenetic defects in spermatozoa of some cancer survivors were evident even up to 2 years post-treatment. Abnormalities in the sperm epigenome both pre- and post-chemotherapy may contribute to detrimental effects on future reproductive health.

Dietary folic acid supplementation improves semen quality and spermatogenesis through altering autophagy and histone methylation in the testis of aged broiler breeder roosters

The aging phenomenon often exerts a significant reduction in the reproduction performance of aged animals. The objective of this project was to investigate the effects of dietary Folic acid (FA) supplementation on the reproductive performance of aged broiler breeder roosters. A total of 16 aged ROSS 308 broiler breeder roosters (50-week-old) were randomly divided into two groups. The treatments were basal diet (CON), a basal diet supplemented with 10 mg/kg Folic acid (FAS) for four weeks. At the end of the experiment, semen quality, histopathological studies, serum concentrations of testosterone and relative mRNA and protein expressions of testes were evaluated. The results showed that dietary FA supplementation dramatically improved semen quality of aged roosters, manifested by increasing semen volume, sperm concentration, sperm motility, and sperm membrane functional integrity. Furthermore, seminiferous tubule epithelial height (SEH) and testis scores were increased by dietary supplementation with FA. Dietary FA also remarkably augmented the transcription level of spermatogenesis-related gene (CREM, PCK2, DDX4, and GDNF). No significant differences were observed in serum concentrations of testosterone between FAS and CON groups. We noted significant upregulation Beclin-1 and ATG5 protein expressions, and the ratio of LC3-Ⅱ/Ⅰ, as well as significant downregulation of p-mTOR protein expressions in testicular tissue of aged roosters with FA supplementation. In addition, dietary FA supplementation significantly increased the protein expression of H3K9me2 and reduced the protein expression of H3K27me2. In summary, dietary FA supplementation improved the testicular autophagy through the mTOR-signaling pathway, and altered histone methylation in the testis. Dietary supplementation with FA can ameliorate semen quality and spermatogenesis of aged roosters.

The impact of zinc and folic acid supplementation on sperm DNA methylation: results from the folic acid and zinc supplementation randomized clinical trial (FAZST)

OBJECTIVE

To determine if 6-month folic acid (5 mg) and zinc (30 mg) supplementation impacts sperm DNA methylation patterns.

DESIGN

A multicenter, double-blind, block randomized, placebo-controlled trial titled "The Folic Acid and Zinc Supplementation Trial (FAZST)."

SETTING

Infertility care centers.

PATIENT(S)

Male partners (18 years and older) from heterosexual couples (female partners aged 18-45 years) seeking fertility treatment were recruited.

INTERVENTION(S)

Men were randomized 1:1 to receive folic acid (5 mg) and elemental zinc (30 mg) (n = 713) or a matching placebo (n = 757) daily for 6 months.

MAIN OUTCOME MEASURE(S)

Sperm DNA methylation was analyzed using the EPIC methylation array (Illumina) at 6 months. Differential sperm DNA methylation was assessed at multiple levels (regional, single cytosine phosphate guanine, etc.). We additionally assessed the impact of supplementation on epigenetic age.

RESULT(S)

No significant differences were identified between the treatment and placebo groups although some trends appeared to be present. To determine if these trends were noteworthy, we implemented various permutations and found that the patterns we identified were no more than would be expected by random chance.

CONCLUSION(S)

The data presented here strongly suggest that this supplementation regimen is not effective at altering sperm DNA methylation. These data comport well with previous findings from the FAZST study that found no impact of supplementation on basic semen analysis parameters or live birth.

CLINICAL TRIAL REGISTRATION NUMBER

ClinicalTrials.gov Identifier: NCT01857310.

The relationship between major dietary patterns and fertility status in iranian men: a case-control study

In this case-control study, we aimed to investigate the association between major dietary patterns and fertility status in Iranian men. The study population included 400 newly diagnosed infertile men and 537 healthy individuals without a history of infertility in Yazd, Iran. Infertility was confirmed clinically, based on the World Health Organization (WHO) criteria. Dietary intake was assessed using a 168-item semi-quantitative food frequency questionnaire (FFQ), and dietary patterns were determined based on a principal component analysis. Four major dietary patterns were found in this study, including healthy, Western, mixed, and traditional dietary patterns. After adjustments for potential confounders, men above the median of a healthy dietary pattern showed a reduced risk of infertility compared to those below the median (OR 0.52; 95% CI 0.33-0.83). In contrast, men with greater adherence to Western and mixed dietary patterns were more likely to be infertile (OR 2.66; 95% CI 1.70-4.17 and OR 2.82; 95% CI 1.75-4.56, respectively). Also, there was no significant association between the traditional dietary pattern and the odds of infertility. The present study suggests that greater adherence to a healthy dietary pattern may have an inverse association with the odds of infertility; however, Western and mixed dietary patterns may be associated with an increased risk of infertility.

DNA methylation in human sperm: a systematic review

BACKGROUND

Studies in non-human mammals suggest that environmental factors can influence spermatozoal DNA methylation, and some research suggests that spermatozoal DNA methylation is also implicated in conditions such as subfertility and imprinting disorders in the offspring. Together with an increased availability of cost-effective methods of interrogating DNA methylation, this premise has led to an increasing number of studies investigating the DNA methylation landscape of human spermatozoa. However, how the human spermatozoal DNA methylome is influenced by environmental factors is still unclear, as is the role of human spermatozoal DNA methylation in subfertility and in influencing offspring health.

OBJECTIVE AND RATIONALE

The aim of this systematic review was to critically appraise the quality of the current body of literature on DNA methylation in human spermatozoa, summarize current knowledge and generate recommendations for future research.

SEARCH METHODS

A comprehensive literature search of the PubMed, Web of Science and Cochrane Library databases was conducted using the search terms 'semen' OR 'sperm' AND 'DNA methylation'. Publications from 1 January 2003 to 2 March 2020 that studied human sperm and were written in English were included. Studies that used sperm DNA methylation to develop methodologies or forensically identify semen were excluded, as were reviews, commentaries, meta-analyses or editorial texts. The Grading of Recommendations, Assessment, Development and Evaluations (GRADE) criteria were used to objectively evaluate quality of evidence in each included publication.

OUTCOMES

The search identified 446 records, of which 135 were included in the systematic review. These 135 studies were divided into three groups according to area of research; 56 studies investigated the influence of spermatozoal DNA methylation on male fertility and abnormal semen parameters, 20 studies investigated spermatozoal DNA methylation in pregnancy outcomes including offspring health and 59 studies assessed the influence of environmental factors on spermatozoal DNA methylation. Findings from studies that scored as 'high' and 'moderate' quality of evidence according to GRADE criteria were summarized. We found that male subfertility and abnormal semen parameters, in particular oligozoospermia, appear to be associated with abnormal spermatozoal DNA methylation of imprinted regions. However, no specific DNA methylation signature of either subfertility or abnormal semen parameters has been convincingly replicated in genome-scale, unbiased analyses. Furthermore, although findings require independent replication, current evidence suggests that the spermatozoal DNA methylome is influenced by cigarette smoking, advanced age and environmental pollutants. Importantly however, from a clinical point of view, there is no convincing evidence that changes in spermatozoal DNA methylation influence pregnancy outcomes or offspring health.

WIDER IMPLICATIONS

Although it appears that the human sperm DNA methylome can be influenced by certain environmental and physiological traits, no findings have been robustly replicated between studies. We have generated a set of recommendations that would enhance the reliability and robustness of findings of future analyses of the human sperm methylome. Such studies will likely require multicentre collaborations to reach appropriate sample sizes, and should incorporate phenotype data in more complex statistical models.

Sperm DNA methylation changes after short-term nut supplementation in healthy men consuming a Western-style diet

BACKGROUND

Many environmental and lifestyle factors have been implicated in the decline of sperm quality, with diet being one of the most plausible factors identified in recent years. Moreover, several studies have reported a close association between the alteration of specific sperm DNA methylation signatures and semen quality.

OBJECTIVES

To evaluate the effect of tree nut consumption on sperm DNA methylation patterns in healthy individuals reporting eating a Western-style diet.

MATERIAL AND METHODS

This is a post hoc analysis conducted in a subset of participants (healthy, non-smoking, and young) from the FERTINUTS 14-wk randomized-controlled, parallel trial, recruited between December 2015 and February 2017. The participants included in the current study (n = 72) were randomly selected in a proportion 2:1 from the original FERTINUTS trial between the 98 participants that completed the entire dietary intervention (nut group, n = 48; control group, n = 24). Sperm DNA methylation patterns were examined at baseline and after 14 weeks in 48 individuals consuming 60 g/d of mixed nuts (nut group) and in 24 individuals following the usual Western-style diet avoiding consumption of nuts (control group).

RESULTS

Over the course of the trial, no significant changes in global methylation were observed between groups. However, in the nut group, we identified 36 genomic regions that were significantly differentially methylated between the baseline and the end of the trial and 97.2% of the regions displayed hypermethylation. We identified no such change in the control group over the same period of time. We also utilized the recently developed germ line age calculator to determine if nut consumption resulted in alterations to the epigenetic age of cells and no significant differences were found.

DISCUSSION AND CONCLUSION

Adding nuts to a regular Western-style diet subtly impacts sperm DNA methylation in specific regions, demonstrating that there are some sperm epigenome regions that could respond to diet.

Repeated sampling facilitates within- and between-subject modeling of the human sperm transcriptome to identify dynamic and stress-responsive sncRNAs

Epidemiological studies from the last century have drawn strong associations between paternal life experiences and offspring health and disease outcomes. Recent studies have demonstrated sperm small non-coding RNA (sncRNA) populations vary in response to diverse paternal insults. However, for studies in retrospective or prospective human cohorts to identify changes in paternal germ cell epigenetics in association with offspring disease risk, a framework must first be built with insight into the expected biological variation inherent in human populations. In other words, how will we know what to look for if we don't first know what is stable and what is dynamic, and what is consistent within and between men over time? From sperm samples from a 'normative' cohort of healthy human subjects collected repeatedly from each subject over 6 months, 17 healthy male participants met inclusion criteria and completed donations and psychological evaluations of perceived stress monthly. sncRNAs (including miRNA, piRNA, and tRNA) isolated from mature sperm from these samples were subjected to Illumina small RNA sequencing, aligned to subtype-specific reference transcriptomes, and quantified. The repeated measures design allowed us to define both within- and between-subject variation in the expression of 254 miRNA, 194 tRNA, and 937 piRNA in sperm over time. We developed screening criteria to identify a subset of potential environmentally responsive 'dynamic' sperm sncRNA. Implementing complex modeling of the relationships between individual dynamic sncRNA and perceived stress states in these data, we identified 5 miRNA (including let-7f-5p and miR-181a-5p) and 4 tRNA that are responsive to the dynamics of prior stress experience and fit our established mouse model. In the current study, we aligned repeated sampling of human sperm sncRNA expression data with concurrent measures of perceived stress as a novel framework that can now be applied across a range of studies focused on diverse environmental factors able to influence germ cell programming and potentially impact offspring development.

The preconception environment and sperm epigenetics

BACKGROUND

Infertility is a common reproductive disorder, with male factor infertility accounting for approximately half of all cases. Taking a paternal perceptive, recent research has shown that sperm epigenetics, such as changes in DNA methylation, histone modification, chromatin structure, and noncoding RNA expression, can impact reproductive and offspring health. Importantly, environmental conditions during the preconception period has been demonstrated to shape sperm epigenetics.

OBJECTIVES

To provide an overview on epigenetic modifications that regulate normal gene expression and epigenetic remodeling that occurs during spermatogenesis, and to discuss the epigenetic alterations that may occur to the paternal germline as a consequence of preconception environmental conditions and exposures.

MATERIALS AND METHODS

We examined published literature available on databases (PubMed, Google Scholar, ScienceDirect) focusing on adult male preconception environmental exposures and sperm epigenetics in epidemiologic studies and animal models.

RESULTS

The preconception period is a sensitive developmental window in which a variety of exposures such as toxicants, nutrition, drugs, stress, and exercise, affects sperm epigenetics.

DISCUSSION AND CONCLUSION

Understanding the environmental legacy of the sperm epigenome during spermatogenesis will enhance our understanding of reproductive health and improve reproductive success and offspring well-being.

Paternal Folate Status and Sperm Quality, Pregnancy Outcomes, and Epigenetics: A Systematic Review and Meta-Analysis

SCOPE

The effectiveness of maternal folate in reducing the risk of congenital malformations during pregnancy is well established. However, the role of the paternal folate status is scarcely investigated. The aim of this study is to investigate the evidence of associations between the paternal folate status and sperm quality, sperm epigenome, and pregnancy outcomes.

METHODS AND RESULTS

Databases are searched up to December 2017 resulting in 3682 articles, of which 23 are retrieved for full-text assessment. Four out of thirteen human and two out of four animal studies show positive associations between folate concentrations and sperm parameters. An additional meta-analysis of four randomized controlled trials in subfertile men shows that the sperm concentration increases (3.54 95% confidence interval (CI) [-1.40 to 8.48]) after 3-6 months of 5 mg folic acid use per day compared to controls. Moreover, two out of two animal and one out of three human studies show significant alterations in the overall methylation of the sperm epigenome. One animal and one human study show associations between low folate intake and an increased risk of congenital malformations.

CONCLUSIONS

This systematic review and meta-analysis shows evidence of associations between paternal folate status and sperm quality, fertility, congenital malformations, and placental weight.

Customized MethylC-Capture Sequencing to Evaluate Variation in the Human Sperm DNA Methylome Representative of Altered Folate Metabolism

BACKGROUND

The sperm DNA methylation landscape is unique and critical for offspring health. If gamete-derived DNA methylation escapes reprograming in early embryos, epigenetic defects in sperm may be transmitted to the next generation. Current techniques to assess sperm DNA methylation show bias toward CpG-dense regions and do not target areas of dynamic methylation, those predicted to be environmentally sensitive and tunable regulatory elements.

OBJECTIVES

Our goal was to assess variation in human sperm DNA methylation and design a targeted capture panel to interrogate the human sperm methylome.

METHODS

To characterize variation in sperm DNA methylation, we performed whole genome bisulfite sequencing (WGBS) on an equimolar pool of sperm DNA from a wide cross section of 30 men varying in age, fertility status, methylenetetrahydrofolate reductase (MTHFR) genotype, and exposures. With our targeted capture panel, in individual samples, we examined the effect of MTHFR genotype ([Formula: see text] 677CC, [Formula: see text] 677TT), as well as high-dose folic acid supplementation ([Formula: see text], per genotype, before and after supplementation).

RESULTS

Through WGBS we discovered nearly 1 million CpGs possessing intermediate methylation levels (20-80%), termed dynamic sperm CpGs. These dynamic CpGs, along with 2 million commonly assessed CpGs, were used to customize a capture panel for targeted interrogation of the human sperm methylome and test its ability to detect effects of altered folate metabolism. As compared with MTHFR 677CC men, those with the 677TT genotype (50% decreased MTHFR activity) had both hyper- and hypomethylation in their sperm. High-dose folic acid supplement treatment exacerbated hypomethylation in MTHFR 677TT men compared with 677CC. In both cases, [Formula: see text] of altered methylation was found in dynamic sperm CpGs, uniquely measured by our assay.

DISCUSSION

Our sperm panel allowed the discovery of differential methylation following conditions affecting folate metabolism in novel dynamic sperm CpGs. Improved ability to examine variation in sperm DNA methylation can facilitate comprehensive studies of environment-epigenome interactions. https://doi.org/10.1289/EHP4812.

Spermatozoal mRNAs expression implicated in embryonic development were influenced by dietary folate supplementation of breeder roosters by altering spermatozoal piRNA expression profiles

Dietary folate intake, together with changes in its metabolism process, have effects on male reproduction, sperm epigenetic patterning and offspring outcome. Previous studies have proven that PIWI-interacting RNAs (piRNAs) play important roles in successful spermatogenesis and regulating genes expression of sperm and offspring embryo. Herein, we fed breeder roosters with five different levels (0, 0.25, 1.25, 2.50, and 5.00 mg/kg) of folate throughout life and found that paternal folate supplementation was beneficial to the growth and organ development of offspring broilers. Further spermatozoal mRNAs sequencing analyses implied that the dietary folate supplementation could regulate the spermatozoal mRNA abundance of genes related to the fetal development. Furthermore, global piRNAs analyses of breeder roosters' sperm revealed that differential concentration of dietary folate supplementation could change piRNAs profiles. Combined mRNAs sequencing and target gene prediction of differentially expressed gene-derived piRNAs, embryonic development and metabolism related pathways and biological processes, which were consisted to the regulatory roles of paternal folate supplementations, were significantly affected by the differentially expressed gene-derived piRNAs based on the GO and KEGG analyses. Overall, our results provided a novel insight into the role of piRNAs in response to folate intake, which will broaden the understanding about the relationship between folate and sperm epigenetic patterning of breeder roosters.

Effect of nut consumption on semen quality and functionality in healthy men consuming a Western-style diet: a randomized controlled trial

BACKGROUND

Human semen quality has declined in industrialized countries. Pollution, smoking, and the consumption of a Western-style diet are all hypothesized as potential causes.

OBJECTIVE

We evaluated the effect of chronic consumption of nuts on changes in conventional semen parameters and the potential mechanisms implicated.

DESIGN

The FERTINUTS study was a 14-wk randomized, controlled, parallel trial. A total of 119 healthy men, aged 18-35 y, were allocated to 1 of 2 intervention groups: one group was fed the usual Western-style diet enriched with 60 g of a mixture of nuts/d (nut group), and the other was fed the usual Western-style diet avoiding nuts (control group). Semen and blood samples were collected at baseline and at the end of the intervention. Dietary information was recorded throughout the trial. Changes in conventional semen parameters (pH, volume, sperm count and concentration, motility, and morphology) were determined as primary outcomes. The effect of nut consumption on sperm DNA fragmentation (SDF), reactive oxygen species (ROS) production, chromosome anomalies (X, Y, and 18), total DNA methylation, and microRNA expression were measured in sperm samples as potential causes of the changes in the seminogram.

RESULTS

Compared with the control group, improvements in total sperm count (P = 0.002) and vitality (P = 0.003), total motility (P = 0.006), progressive motility (P = 0.036), and morphology of sperm (P = 0.008) were observed in the nut group. Participants in the nut group showed an increase in the consumption of total fat, monounsaturated fatty acids, polyunsaturated fatty acids, magnesium, vitamin E, α-linolenic acid, total omega-3 (n-3) and ω-3:ω-6 ratio intake during the intervention. Participants in the nut group showed a significant reduction in SDF (P < 0.001) and in the expression of hsa-miR-34b-3p (P = 0.036). No significant changes in ROS, sperm chromosome anomalies, or DNA methylation were observed between groups.

CONCLUSIONS

The inclusion of nuts in a Western-style diet significantly improves the total sperm count and the vitality, motility, and morphology of the sperm. These findings could be partly explained by a reduction in the sperm DNA fragmentation. This trial was registered at ISRCTN as ISRCTN12857940.

Effects of dietary interventions on DNA methylation in adult humans: systematic review and meta-analysis

DNA methylation is a key component of the epigenetic machinery that is responsible for regulating gene expression and, therefore, cell function. Patterns of DNA methylation change during development and ageing, differ between cell types, are altered in multiple diseases and can be modulated by dietary factors. However, evidence about the effects of dietary factors on DNA methylation patterns in humans is fragmentary. This study was initiated to collate evidence for causal links between dietary factors and changes in DNA methylation patterns. We carried out a systematic review of dietary intervention studies in adult humans using Medline, EMBASE and Scopus. Out of 22 149 screened titles, sixty intervention studies were included, of which 65% were randomised (n 39). Most studies (53%) reported data from blood analyses, whereas 27% studied DNA methylation in colorectal mucosal biopsies. Folic acid was the most common intervention agent (33%). There was great heterogeneity in the methods used for assessing DNA methylation and in the genomic loci investigated. Meta-analysis of the effect of folic acid on global DNA methylation revealed strong evidence that supplementation caused hypermethylation in colorectal mucosa (P=0·009). Meta-regression analysis showed that the dose of supplementary folic acid was the only identified factor (P<0·001) showing a positive relationship. In summary, there is limited evidence from intervention studies of effects of dietary factors, other than folic acid, on DNA methylation patterns in humans. In addition, the application of multiple different assays and investigations of different genomic loci makes it difficult to compare, or to combine, data across studies.

Preconception urinary phthalate concentrations and sperm DNA methylation profiles among men undergoing IVF treatment: a cross-sectional study

STUDY QUESTION

Are preconception phthalate and phthalate replacements associated with sperm differentially methylated regions (DMRs) among men undergoing IVF?

SUMMARY ANSWER

Ten phthalate metabolites were associated with 131 sperm DMRs that were enriched in genes related to growth and development, cell movement and cytoskeleton structure.

WHAT IS KNOWN ALREADY

Several phthalate compounds and their metabolites are known endocrine disrupting compounds and are pervasive environmental contaminants. Rodent studies report that prenatal phthalate exposures induce sperm DMRs, but the influence of preconception phthalate exposure on sperm DNA methylation in humans is unknown.

STUDY DESIGN, SIZE, DURATION

An exploratory cross-sectional study with 48 male participants from the Sperm Environmental Epigenetics and Development Study (SEEDS).

PARTICIPANTS/MATERIALS, SETTING, METHODS

The first 48 couples provided a spot urine sample on the same day as semen sample procurement. Sperm DNA methylation was assessed with the HumanMethylation 450 K array. Seventeen urinary phthalate and 1,2-Cyclohexane dicarboxylic acid diisononyl ester (DINCH) metabolite concentrations were measured from spot urine samples. The A-clust algorithm was employed to identify co-regulated regions. DMRs associated with urinary metabolite concentrations were identified via linear models, corrected for false discovery rate (FDR).

MAIN RESULTS AND ROLE OF CHANCE

Adjusting for age, BMI, and current smoking, 131 DMRs were associated with at least one urinary metabolite. Most sperm DMRs were associated with anti-androgenic metabolites, including mono(2-ethylhexyl) phthalate (MEHP, n = 83), mono(2-ethyl-5-oxohexyl) phthalate (MEOHP, n = 16), mono-n-butyl phthalate (MBP, n = 22) and cyclohexane-1,2-dicarboxylic acid-monocarboxy isooctyl (MCOCH, n = 7). The DMRs were enriched in lincRNAs as well as in regions near coding regions. Functional analyses of DMRs revealed enrichment of genes related to growth and development as well as cellular function and maintenance. Finally, 13% of sperm DMRs were inversely associated with high quality blastocyst-stage embryos after IVF.

LIMITATIONS, REASONS FOR CAUTION

Our modest sample size only included 48 males and additional larger studies are necessary to confirm our observed results. Non-differential misclassification of exposure is also a concern given the single spot urine collection.

WIDER IMPLICATIONS OF THE FINDINGS

To our knowledge, this is the first study to report that preconception urinary phthalate metabolite concentrations are associated with sperm DNA methylation in humans. These results suggest that paternal adult environmental conditions may influence epigenetic reprogramming during spermatogenesis, and in turn, influence early-life development.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by grant K22-ES023085 from the National Institute of Environmental Health Sciences. The authors declare no competing interests.

Effect of adding B-vitamins to vitamin D and calcium supplementation on CpG methylation of epigenetic aging markers

BACKGROUND AND AIM

B-vitamins may influence DNA methylation. We studied the effects of vitamin D + Ca + B versus D + Ca on epigenetic age markers and biological age.

METHODS AND RESULTS

Participants (mean ± SD of age = 68.4 ± 10.1 years) were randomized to receive 1200 IE vitamin D3 plus 800 mg Ca-carbonate alone (n = 31) or with 0.5 mg B9, 50 mg B6, and 0.5 mg B12 (n = 32). The CpG methylation of 3 genes (ASPA, ITGA2B, and PDE4C) and the changes in methylation were compared between the groups after 1 year. The changes of ASPA methylation from baseline were higher in the D + Ca + B than in the D + Ca group (1.40 ± 4.02 vs. -0.96 ± 5.12, respectively; p = 0.046, adjusted for age, sex, and baseline methylation). The changes in PDE4C from baseline were slightly higher in the D + Ca + B group (1.95 ± 3.57 vs. 0.22 ± 3.57; adjusted p = 0.062). Methylation of ITGA2B and its changes from baseline were not different between the intervention groups. Sex-adjusted odds ratio of accelerated aging (chronological age < biological age at 1 year) was 5.26 (95% confidence interval 1.51-18.28) in the D + Ca + B compared with the D + Ca group. Accelerated aging in both groups was associated with younger age. In the D + Ca + B group, it was additionally associated with lower baseline homocysteine.

CONCLUSIONS

Vitamin D + Ca + B and D + Ca differentially affected epigenetic age markers, although the effect size appeared to be small after 1 year. B-vitamins effect in young subjects with low homocysteine requires further investigation. ClinicalTrials.gov ID: NCT02586181.

Developmental Origins of Breast Cancer: A Paternal Perspective

The developmental origins of breast cancer have been considered predominantly from a maternal perspective. Although accumulating evidence suggests a paternal programming effect on metabolic diseases, the potential impact of fathers' experiences on their daughters' breast cancer risk has received less attention. In this chapter, we focus on the developmental origins of breast cancer and examine the emerging evidence for a role of fathers' experiences.

Effects of administration of co-trimoxazole and folic acid on sperm quality and histological changes of testes in male rats

BACKGROUND

Male infertility has been reported following long-term sulfasalazine, however, the precise effects of co-trimoxazole on sperm quality is controversial.

OBJECTIVE

In this study, we evaluated the effects of co-trimoxazole and its co-administration with folic acid on sperm quality and histological changes of testes in male rats.

MATERIALS AND METHODS

In this experimental study, 136 male Wistar rats were divided into 9 groups: I (control), II (vehicle) received saline, III: received folic acid (1 mg/kg /daily i.p., and IV- IX received co-trimoxazole (30, 60, and 120 mg/kg/daily; i.p.)+folic acid (1 mg/kg/daily; i.p.) for 14 or 28 days. Sperm samples were obtained from each group at the end of 14^th and 28^th days. Sperm numbers, motility, and viability were evaluated on a hemocytometer. Hematoxylin and Eosin stained testes were done for evaluation ofthe number of Leydig cells, vascularity, spermatids, spermatocytes, and means of seminiferous tubules diameter under light microscopy.

RESULTS

Co-trimoxazole treatment for either 14 or 28 days caused a significant decrease in the percentage of sperm number, motility, and viability (p<0.001) compared to the control group. Also, high doses of co-trimoxazole caused a significant decrease in testes structural abnormalities means of seminiferous tubules diameter, spermatids, and spermatogonia) compared to the vehicle group (p<0.001). Folic acid co-administration with co-trimoxazole partially reversed the decrease in sperm quality and structural abnormalities of high doses of co-trimoxazole (60 and 120 mg/kg/daily) (p<0.001).

CONCLUSION

The data showed the adverse effects of co-trimoxazole on sperm quality and testes morphology which was protected partially by folic acid co-administration in rats. The underlying mechanism (s) needs further investigations.