The preconception environment and sperm epigenetics

Paternal peri-conceptional physical activity and the risk of congenital heart disease in offspring: A case-control study

BACKGROUND

Genetic and environmental factors have been shown to contribute to the development of congenital heart disease (CHD). To date, the focus of scientific articles has primarily centered on genetics and maternal environmental factors, with comparatively less attention given to paternal risk factors.

OBJECTIVES

This study aims to investigate the potential association between paternal pre-conceptional physical activity levels (PA), along with paternal peri-conceptional smoking and alcohol consumption, and the risk of CHD in offspring.

MATERIALS AND METHODS

An observational case-control study was conducted in Lebanon, with 279 participants, aiming to investigate potential risk factors for CHD. We included children with confirmed CHD, born between 2012 and 2022. Controls born in the same timeframe were selected randomly from the general population using online questionnaire forms. Mean age of children included was 6 years old (0-10). The pre-conceptional PA was assessed using the Global Physical Activity Questionnaire validated in Arabic. In addition, paternal smoking, alcohol consumption, and maternal risk factors were collected.

RESULTS

The study included 128 CHD cases (45.9%) and their parents, as well as 151 healthy infants (54.1%) and their parents. There were no statistically significant variations in the alcohol consumption noted between the fathers in the case and control groups (p = 0.18). The paternal involvement in recreational-related PA during the peri-conception period was associated with a reduced risk of the CHD development in offspring by 46.9% (OR = 0.531, 95% CI: 0.301-0.936, p = 0.029). Additionally, increasing paternal total sitting time by 1 h above the average, which was approximately 260 min (4 h), increased the risk of CHD in offspring by 0.4% (p = 0.001). Moreover, paternal smoking exhibited an apparent association with a 56% increased risk of offspring developing CHD, notwithstanding that the confidence intervals included the null (OR = 1.56, 95% CI: 0.86-2.8, p = 0.136).

DISCUSSION AND CONCLUSION

This observational study is the first to report a potential association between paternal PA, and CHD in offspring. This study aligns with previous reports, advocating for the paternal engagement in PA and the adoption of healthy lifestyle habits, especially during the critical stages of conception. Such practices are strongly recommended to enhance fertility and promote optimal health for offspring. However, due to the subjectivity in reporting PA and lack of molecular proof, additional prospective and molecular studies are required to validate these findings.

Fine particulate matter‑induced cardiac developmental toxicity (Review)

Fine particulate matter (PM2.5) has become an important risk factor threatening human health. Epidemiological and toxicological investigations have revealed that PM2.5 not only leads to cardiovascular dysfunction, but it also gives rise to various adverse health effects on the human body, such as cardiovascular and cerebrovascular diseases, cancers, neurodevelopmental disorders, depression and autism. PM2.5 is able to penetrate both respiratory and placental barriers, thereby resulting in negative effects on fetal development. A large body of epidemiological evidences has suggested that gestational exposure to PM2.5 increases the incidence of congenital diseases in offspring, including congenital heart defects. In addition, animal model studies have revealed that gestational exposure to PM2.5 can disrupt normal heart development in offspring, although the potential molecular mechanisms have yet to be fully elucidated. The aim of the present review was to provide a brief overview of what is currently known regarding the molecular mechanisms underlying cardiac developmental toxicity in offspring induced by gestational exposure to PM2.5.

Impact of sperm sex sorting on sperm quality and in vitro embryo production in bovine

Increasing evidence suggests that environmental exposures can modify epigenetic marks in the germline, leading to the transmission of abnormal post-fertilization sperm epigenetic indicators and affecting embryonic development. Given the pivotal role of sperm cells in determining embryo quality, there is growing interest in understanding the potential effects of sperm sex sorting on embryo quality. This study aimed to investigate the impact of bovine sperm sexing on in vitro embryo production (IVP) and to associate molecular aspects of embryos analysis. Frozen semen samples from five Nellore bulls were used, with each bull contributing unsexed sperm (conventional semen - CV treatment) and female and male sexed sperm pooled after thawing (SX treatment). First, semen quality was assessed, including motility, morphology, acrosome integrity, and chromatin integrity to denaturation. Then, IVP was carried out, focusing on embryonic production and developmental kinetics. In the third experiment, embryo quality was evaluated by examining the gene expression of key markers (OCT4, NANOG, DNMT3A, TET1, and Fematrin-1) and the methylation pattern of the Satellite-1 and α-Satellite genes in blastocysts. Differences between CV and SX semen were only observed in motility, which was lower in SX compared with CV (P < 0.05). Although cleavage was similar, the SX groups showed lower blastocyst production than CV (P < 0.05). Of the genes evaluated, only NANOG showed high expression in the CV blastocysts compared with the SX blastocysts, but the methylation pattern revealed no differences. In conclusion, sex sorting markedly affects sperm motility and in vitro embryo production but showed no significant impact on embryo quality.

Environmental exposures influence multigenerational epigenetic transmission

Epigenetic modifications control gene expression and are essential for turning genes on and off to regulate and maintain differentiated cell types. Epigenetics are also modified by a multitude of environmental exposures, including diet and pollutants, allowing an individual's environment to influence gene expression and resultant phenotypes and clinical outcomes. These epigenetic modifications due to gene-environment interactions can also be transmitted across generations, raising the possibility that environmental influences that occurred in one generation may be transmitted beyond the second generation, exerting a long-lasting effect. In this review, we cover the known mechanisms of epigenetic modification acquisition, reprogramming and persistence, animal models and human studies used to understand multigenerational epigenetic transmission, and examples of environmentally induced epigenetic change and its transmission across generations. We highlight the importance of environmental health not only on the current population but also on future generations that will experience health outcomes transmitted through epigenetic inheritance.

Impact of metabolic syndrome factors on sperm DNA fragmentation in males from infertile couples: A systematic review and meta-analysis

PURPOSE

To investigate the impact of metabolic syndrome factors on sperm DNA fragmentation (sDF) in males from infertile couples.

METHODS

A systematic literature search was performed across ten databases for literature published from January 1, 2013 until September 13, 2023. The protocol has been registered on PROSPERO (CRD42023458359), and the literature search strategy is adhered to the PRISMA framework. Studies that evaluated sDF, as indicated by DNA fragmentation index (%DFI), in males from infertile couples in relation to metabolic syndrome factors were included. Meta-analysis, using random effects model and Bayesian framework network, was performed, and data were presented as Standardized Mean Differences (SMD) with corresponding 95 % Confidence Interval (CI).

RESULTS

Of the 2579 citations identified, eleven studies were included in this meta-analysis. The findings revealed that the %DFI was not associated with overall metabolic syndrome factors (p-tot = 0.235; SMD = 0.57 [95 %CI: -0.37, 1.52]), metabolic syndrome status (p-tot = 0.337; SMD = 0.08 [95 %CI: -0.08, 0.24), increased body mass index (p-tot = 0.237; SMD = 0.71 [95 %CI: -0.47, 1.89]), or glycaemic profile (p-tot = 0.93; SMD = 0.13 [95 %CI: -2.72, 2.98]). High levels of heterogeneity were observed (p < 0.01) in all subgroups, except for metabolic syndrome status.

CONCLUSION

The association between metabolic syndrome factors and sDF is conflicting. However, interpreting the association requires caution, as confounding factors, indicated by high heterogeneity, may conceal the outcome. Metabolic syndrome may influence other factors contributing to male infertility, highlighting the importance of promoting a healthy lifestyle.

Urinary concentrations of phthalate and phthalate alternative metabolites and sperm DNA methylation: A multi-cohort and meta-analysis of men in preconception studies

Phthalates are ubiquitous pollutants in the environment; however, the mechanisms of phthalate-associated reproductive disorders in men are not fully understood. The aim of this study is to investigate associations between urinary phthalate metabolite concentrations and sperm DNA methylation. The study was conducted on 697 men from three prospective pregnancy cohorts: Longitudinal Investigation of Fertility and the Environment (LIFE) Study, Sperm Environmental Epigenetics and Development Study (SEEDS), and Environment and Reproductive Health (EARTH) Study. Eighteen phthalate and two phthalate alternative metabolites were quantified by mass spectrometry in preconception urinary samples and sperm DNA methylation was measured via Illumina EPIC Array (v1). Regional methylation analyses were conducted to identify cohort-specific loci associated with urinary phthalate metabolites. Models were adjusted for age, body mass index (BMI), race, smoking status, urinary creatinine/specific gravity, and analytical batch for phthalate measurements. The cohort-specific results were meta-analyzed using METAL. Participants had an average age of 30 years, most (79.6 %) of whom had BMI>25 kg/m2 and were non-smokers (90.1 %). A total of 7,979 differentially methylated regions (DMRs; 7,979 LIFE-specific DMRs, 72 SEEDS-specific DMRs, and 23 EARTH-specific DMRs) were associated with urinary MBzP, MiBP, MMP, MCNP, MCPP, MBP, and MCOCH. Meta-analysis identified fewer DMRs than cohort-specific models: 946 DMRs were associated with MBzP, 27 DMRs associated with MiBP, and 1 DMR associated with MEHP. The majority of cohort-specific and meta-analysis-derived DMRs displayed a positive association with phthalate metabolite concentrations and were enriched in genes associated with spermatogenesis, response to hormones and their metabolism, embryonic organ development and developmental growth. In conclusion, several preconception urinary phthalate metabolites were associated with increased DNA methylation patterns in sperm. These findings provide an epigenetic pathway by which environmental phthalate exposures can impact couples' reproductive outcomes.

Impact of heat waves on semen quality: A retrospective study in Argentina between 2005 and 2023

Heat waves, defined as periods with daily temperatures surpassing the historical average for a specific region, have become more frequent worldwide in recent years. Previous studies have reported a negative association between temperature and semen quality, but the focus has mainly been on Asian and European populations. The study included 54,926 men (18-60 years) undergoing routine semen analysis between 2005 and 2023 at CEUSA-LAEH andrology unit, in Buenos Aires, Argentina. Hourly temperature readings were provided by the Servicio Meteorológico Nacional. R programming (R Studio v2022.07.2) was used to define heat waves, calculate key characteristics, visualize results, and perform statistical tests at the IBYME laboratory. During the period studied, a total of 124 days had heat waves (defined after at least 3 consecutive days with 32.3 °C and 22 °C). Men exposed to heat waves during spermatogenesis exhibited lower sperm number (concentration and count; P < 0.0001) and decreased normal morphology (percentage of normal sperm and normal motile count; P < 0.05) compared to those not exposed. These differences were most pronounced between semen samples from years with several heat waves (2013, 2023) and none (2005, 2007, 2016), displaying 4-5 times higher fold changes (P < 0.05). Further analysis employing multiple regression revealed a significantly negative association between semen quality and heat wave length, suggesting that a prolonged exposure may be more detrimental than an acute exposure. Subsequent analysis focusing on prolonged exposure (≥6-days heat wave) during spermatogenesis revealed a negative (P < 0.05) association between early exposure (spermatocytogenesis: 64-90 days prior semen collection) and semen quality. This study underscores the negative association between early exposure to heat waves during sperm development and semen quality, raising concerns about its possible association with the worldwide declining male fertility. A comprehensive collaborative approach is crucial, involving global governmental policies, sustainable practices, and coordinated efforts across scientific, healthcare, and policy domains.

PM2.5 threshold exceedances during the prenatal period and risk of intellectual disability

BACKGROUND

Research demonstrates that chronic exposure to fine particulates (PM2.5) increases risks of neurodevelopmental conditions, such as intellectual disability (ID). Few studies have examined neurodevelopmental health impacts of pollution spikes exceeding 24-h (24-h) PM2.5 guidelines, despite relevance to the regulatory landscape. The current potential for regulatory changes to 24-h PM2.5 standards in the United States makes research on exceedances relevant.

OBJECTIVE

To examine associations between 24-h PM2.5 exceedances and the risk of ID.

METHODS

We conducted a retrospective case-control study of a sample of children in Utah, USA. We used generalized estimating equations to predict odds of ID based on the number of 24-h PM2.5 exceedance days during the preconception period and three trimesters of pregnancy. Exceedance days are defined as per current World Health Organization (WHO) [≥15 μg/m3] and current US Environmental Protection Agency (EPA) [≥35 μg/m3] 24-h guidelines.

RESULTS

PM2.5 exceedances are associated with ID risk during the preconception and first trimester periods and not the second and third trimesters. During the preconception period, each day exceeding 15 μg/m3 or 35 μg/m3 was associated with a 1.023 (CI: 1.011-1.040) or 1.042 (CI: 1.026-1.059, p < 0.001) increase in odds of ID, respectively. During the first trimester, each day exceeding 15 μg/m3 or 35 μg/m3 was associated with a 1.032 (CI: 1.017-1.047) or 1.059 (CI: 1.030-1.088) increase in odds of ID, respectively.

IMPACT STATEMENT

Potential regulatory movement on the US 24-h PM2.5 standard makes research that explicitly studies exceedances highly relevant. Yet few studies examine health effects of exceeding 24-h guidelines for any air pollutants. This study fills important gaps in the literature by examining associations between odds of intellectual disability and the count of days exceeding current 24-h PM2.5 guidelines, as established by the World Health Organization and US Environmental Protection Agency, during the prenatal period. We find that exceedances of both sets of guidelines, during the preconception and first trimester periods, are associated with ID risk.

Unfolding the complexity of epigenetics in male reproductive aging: a review of therapeutic implications

INTRODUCTION

Epigenetics studies gene expression changes influenced by environmental and lifestyle factors, linked to health conditions like reproductive aging. Male reproductive aging causes sperm decline, conceiving difficulties, and increased genetic abnormalities. Recent research focuses on epigenetics' role in male reproductive aging.

OBJECTIVES

This review explores epigenetics and male reproductive aging, focusing on sperm quality, environmental and lifestyle factors' impact, and potential health implications for offspring.

METHODS

An extensive search of the literature was performed applying multiple databases, such as PubMed and Google Scholar. The search phrases employed were: epigenetics, male reproductive ageing, sperm quality, sperm quantity, environmental influences, lifestyle factors, and offspring health. This review only included articles that were published in English and had undergone a peer-review process. The literature evaluation uncovered that epigenetic alterations have a substantial influence on the process of male reproductive ageing.

RESULT

Research has demonstrated that variations in the quality and quantity of sperm that occur with ageing are linked to adjustments in DNA methylation and histone. Moreover, there is evidence linking epigenetic alterations in sperm to environmental and lifestyle factors, including smoking, alcohol intake, and exposure to contaminants. These alterations can have enduring impacts on the well-being of descendants, since they can shape the activation of genes and potentially elevate the likelihood of genetic disorders. In conclusion, epigenetics significantly influences male reproductive aging, with sperm quality and quantity influenced by environmental and lifestyle factors.

CONCLUSION

This underscores the need for comprehensive approaches to managing male reproductive health, and underscores the importance of considering epigenetics in diagnosis and treatment.

A comprehensive insight into the contribution of epigenetics in male infertility; focusing on immunological modifications

Numerous recent studies have examined the impact epigenetics-including DNA methylation-has on spermatogenesis and male infertility. Differential methylation of several genes has been linked to compromised spermatogenesis and/or reproductive failure. Specifically, male infertility has been frequently associated with DNA methylation abnormalities of MEST and H19 inside imprinted genes and MTHFR within non-imprinted genes. Microbial infections mainly result in male infertility because of the immune response triggered by the bacteria' accumulation of immune cells, proinflammatory cytokines, and chemokines. Thus, bacterially produced epigenetic dysregulations may impact host cell function, supporting host defense or enabling pathogen persistence. So, it is possible to think of pathogenic bacteria as potential epimutagens that can alter the epigenome. It has been demonstrated that dysregulated levels of LncRNA correlate with motility and sperm count in ejaculated spermatozoa from infertile males. Therefore, a thorough understanding of the relationship between decreased reproductive capacity and sperm DNA methylation status should aid in creating new diagnostic instruments for this condition. To fully understand the mechanisms influencing sperm methylation and how they relate to male infertility, more research is required.

Associations of air pollution exposures in preconception and pregnancy with birth outcomes and infant neurocognitive development: analysis of the Complex Lipids in Mothers and Babies (CLIMB) prospective cohort in Chongqing, China

OBJECTIVES

To investigate the associations of traffic-related air pollution exposures in early pregnancy with birth outcomes and infant neurocognitive development.

DESIGN

Cohort study.

SETTING

Eligible women attended six visits in the maternity clinics of two centres, the First Affiliated Hospital of Chongqing Medical University and Chongqing Health Centre for Women and Children.

PARTICIPANTS

Women who were between 20 and 40 years of age and were at 11-14 weeks gestation with a singleton pregnancy were eligible for participation. Women were excluded if they had a history of premature delivery before 32 weeks of gestation, maternal milk allergy or aversion or severe lactose intolerance. 1273 pregnant women enrolled in 2015-2016 and 1174 live births were included in this analysis.

EXPOSURES

Air pollution concentrations at their home addresses, including particulate matter with diameter ≤2.5 µm (PM2.5) and nitrogen dioxide (NO2), during pre-conception and each trimester period were estimated using land-use regression models.

OUTCOME MEASURES

Birth outcomes (ie, birth weight, birth length, preterm birth, low birth weight, large for gestational age and small for gestational age (SGA) status) and neurodevelopment outcomes measured by the Chinese version of Bayley Scales of Infant Development.

RESULTS

An association between SGA and per-IQR increases in NO2 was found in the first trimester (OR: 1.57, 95% CI: 1.06 to 2.32) and during the whole pregnancy (OR: 1.33, 99% CI: 1.01 to 1.75). Both PM2.5 and NO2 exposure in the 90 days prior to conception were associated with lower Psychomotor Development Index scores (β: -6.15, 95% CI: -8.84 to -3.46; β: -2.83, 95% CI: -4.27 to -1.39, respectively). Increased NO2 exposure was associated with an increased risk of psychomotor development delay during different trimesters of pregnancy.

CONCLUSIONS

Increased exposures to NO2 during pregnancy were associated with increased risks of SGA and psychomotor development delay, while increased exposures to both PM2.5 and NO2 pre-conception were associated with adverse psychomotor development outcomes at 12 months of age.

TRIAL REGISTRATION NUMBER

ChiCTR-IOR-16007700.

Paternal Inflammatory Bowel Disease and the Risk of Pregnancy Loss

BACKGROUND

Only about 30% of conceptions end in live births, yet there are little data on paternal causes of pregnancy loss. Men with inflammatory bowel disease may have multiple disease-related issues that may affect fertility. We aimed to examine pregnancy outcomes in women undergoing assisted reproduction whose male partners had Crohn's disease or ulcerative colitis.

METHODS

This nationwide study included all embryo transfers registered in the Danish Assisted Reproduction Registry from January 2, 2006, to September 3, 2019. The exposed cohort included embryo transfers from couples in which the male partners had Crohn's disease or ulcerative colitis. The unexposed cohort included embryo transfers in which male partners did not have inflammatory bowel disease.

RESULTS

For fathers with ulcerative colitis, the adjusted odds ratio for a positive biochemical pregnancy (positive human chorionic gonadotropin) was 1.14 (95% confidence interval [CI], 0.92-1.42), for a clinical pregnancy (positive vaginal ultrasonography at 7-8 weeks) was 0.91 (95% CI, 0.59-1.40), and for a live birth was 0.99 (95% CI, 0.71-1.60). For fathers with Crohn's disease, the adjusted odds ratio for a biochemical pregnancy was 0.83 (95% CI, 0.63-1.09), for a clinical pregnancy was 0.58 (95% CI, 0.34-0.97), and for a live birth was 0.88 (95% CI, 0.51-1.55).

CONCLUSIONS

These findings may indicate that partners of men with Crohn's disease may have an increased risk of early pregnancy loss. Future studies should confirm these results and examine the impact of paternal medications, paternal disease activity, and other factors associated with chronic inflammatory bowel disease.

Exploring online reproductive health promotion in Canada: a focus on behavioral and environmental influences from a sex and gender perspective

BACKGROUND

Reproductive health promotion can enable early mitigation of behavioral and environmental risk factors associated with adverse pregnancy outcomes, while optimizing health of women + (all genders that can gestate a fetus) and babies. Although the biological and social influences of partners on pregnancy are well established, it is unknown whether online Canadian government reproductive health promotion also targets men and partners throughout the reproductive lifespan.

METHODS

Reproductive health promotion, designed for the general public, was assessed in a multi-jurisdictional sample of Canadian government (federal, provincial/territorial, and municipal) and select non-governmental organization (NGO) websites. For each website, information related to environmental and behavioral influences on reproductive health (preconception, pregnancy, postpartum) was evaluated based on comprehensiveness, audience-specificity, and scientific quality.

RESULTS

Government and NGO websites provided sparse reproductive health promotion for partners which was generally limited to preconception behavior topics with little coverage of environmental hazard topics. For women + , environmental and behavioral influences on reproductive health were well promoted for pregnancy, with content gaps for preconception and postpartum stages.

CONCLUSION

Although it is well established that partners influence pregnancy outcomes and fetal/infant health, Canadian government website promotion of partner-specific environmental and behavioral risks was limited. Most websites across jurisdictions promoted behavioral influences on pregnancy, however gaps were apparent in the provision of health information related to environmental hazards. As all reproductive stages, including preconception and postpartum, may be susceptible to environmental and behavioral influences, online health promotion should use a sex- and gender-lens to address biological contributions to embryo, fetal and infant development, as well as contributions of partners to the physical and social environments of the home.

Future in the past: paternal reprogramming of offspring phenotype and the epigenetic mechanisms

That certain preconceptual paternal exposures reprogram the developmental phenotypic plasticity in future generation(s) has conceptualized the "paternal programming of offspring health" hypothesis. This transgenerational effect is transmitted primarily through sperm epigenetic mechanisms-DNA methylation, non-coding RNAs (ncRNAs) and associated RNA modifications, and histone modifications-and potentially through non-sperm-specific mechanisms-seminal plasma and circulating factors-that create 'imprinted' memory of ancestral information. The epigenetic landscape in sperm is highly responsive to environmental cues, due to, in part, the soma-to-germline communication mediated by epididymosomes. While human epidemiological studies and experimental animal studies have provided solid evidences in support of transgenerational epigenetic inheritance, how ancestral information is memorized as epigenetic codes for germline transmission is poorly understood. Particular elusive is what the downstream effector pathways that decode those epigenetic codes into persistent phenotypes. In this review, we discuss the paternal reprogramming of offspring phenotype and the possible underlying epigenetic mechanisms. Cracking these epigenetic mechanisms will lead to a better appreciation of "Paternal Origins of Health and Disease" and guide innovation of intervention algorithms to achieve 'healthier' outcomes in future generations. All this will revolutionize our understanding of human disease etiology.

Prenatal exposure to Di(2-ethylhexyl) phthalate and high-fat diet synergistically disrupts gonadal function in male mice†

Prenatal exposure to Di (2-ethylhexyl) phthalate (DEHP) impairs the reproductive system and causes fertility defects in male offspring. Additionally, high-fat (HF) diet is a risk factor for reproductive disorders in males. In this study, we tested the hypothesis that prenatal exposure to a physiologically relevant dose of DEHP in conjunction with HF diet synergistically impacts reproductive function and fertility in male offspring. Female mice were fed a control or HF diet 7 days prior to mating and until their litters were weaned on postnatal day 21. Pregnant dams were exposed to DEHP or vehicle from gestational day 10.5 until birth. The male offspring's gross phenotype, sperm quality, serum hormonal levels, testicular histopathology, and testicular gene expression pattern were analyzed. Male mice born to dams exposed to DEHP + HF had smaller testes, epididymides, and shorter anogenital distance compared with those exposed to HF or DEHP alone. DEHP + HF mice had lower sperm concentration and motility compared with DEHP mice. Moreover, DEHP + HF mice had more apoptotic germ cells, fewer Leydig cells, and lower serum testosterone levels than DEHP mice. Furthermore, testicular mRNA expression of Dnmt1 and Dnmt3a was two to eight-fold higher than in DEHP mice by qPCR, suggesting that maternal HF diet and prenatal DEHP exposure additively impact gonadal function by altering the degree of DNA methylation in the testis. These results suggest that the combined exposure to DEHP and high-fat synergistically impairs reproductive function in male offspring, greater than exposure to DEHP or HF diet alone.

Epigenetic programming for obesity and noncommunicable disease: From womb to tomb

Several epidemiological, clinical and experimental studies in recent decades have shown the relationship between exposure to stressors during development and health outcomes later in life. The characterization of these susceptible phases, such as preconception, gestation, lactation and adolescence, and the understanding of factors that influence the risk of an adult individual for developing obesity, metabolic and cardiovascular diseases, is the focus of the DOHaD (Developmental Origins of Health and Disease) research line. In this sense, advancements in molecular biology techniques have contributed significantly to the understanding of the mechanisms underlying the observed phenotypes, their morphological and physiological alterations, having as a main driving factor the epigenetic modifications and their consequent modulation of gene expression. The present narrative review aimed to characterize the different susceptible phases of development and associated epigenetic modifications, and their implication in the development of non-communicable diseases. Additionally, we provide useful insights into interventions during development to counteract or prevent long-term programming for disease susceptibility.

Mixtures of per- and polyfluoroalkyl substances (PFAS) alter sperm methylation and long-term reprogramming of offspring liver and fat transcriptome

Male fertility has been declining worldwide especially in countries with high levels of endocrine disrupting chemicals (EDCs). Per- and polyfluorinated alkyl Substances (PFAS) have been classified as EDCs and have been linked to adverse male reproductive health. The mechanisms of these associations and their implications on offspring health remain unknown. The aims of the current study were to assess the effect of PFAS mixtures on the sperm methylome and transcriptional changes in offspring metabolic tissues (i.e., liver and fat). C57BL/6 male mice were exposed to a mixture of PFAS (PFOS, PFOA, PFNA, PFHxS, Genx; 20 µg/L each) for 18-weeks or water as a control. Genome-wide methylation was assessed on F0 epidydimal sperm using reduced representation bisulfite sequencing (RRBS) and Illumina mouse methylation array, while gene expression was assessed by bulk RNA sequencing in 8-week-old offspring derived from unexposed females. PFAS mixtures resulted in 2,861 (RRBS) and 83 (Illumina) sperm DMRs (q < 0.05). Functional enrichment revealed that PFAS-induced sperm DMRs were associated with behavior and developmental pathways in RRBS, while Illumina DMRs were related to lipid metabolism and cell signaling. Additionally, PFAS mixtures resulted in 40 and 53 differentially expressed genes (DEGs) in the liver and fat of males, and 9 and 31 DEGs in females, respectively. Functional enrichment of DEGs revealed alterations in cholesterol metabolism and mitotic cell cycle regulation in the liver and myeloid leukocyte migration in fat of male offspring, while in female offspring, erythrocyte development and carbohydrate catabolism were affected in fat. Our results demonstrate that exposure to a mixture of legacy and newly emerging PFAS chemicals in adult male mice result in aberrant sperm methylation and altered gene expression of offspring liver and fat in a sex-specific manner. These data indicate that preconception PFAS exposure in males can be transmitted to affect phenotype in the next generation.

Epigenetic Factor MicroRNAs Likely Mediate Vaccine Protection Efficacy against Lymphomas in Response to Tumor Virus Infection in Chickens through Target Gene Involved Signaling Pathways

Epigenetic factors, including microRNAs (miRNAs), play an important role in affecting gene expression and, therefore, are involved in various biological processes including immunity protection against tumors. Marek's disease (MD) is a highly contagious disease of chickens caused by the MD virus (MDV). MD has been primarily controlled by vaccinations. MD vaccine efficacy might, in part, be dependent on modulations of a complex set of factors including host epigenetic factors. This study was designed to identify differentially expressed miRNAs in the primary lymphoid organ, bursae of Fabricius, in response to MD vaccination followed by MDV challenge in two genetically divergent inbred lines of White Leghorns. Small RNA sequencing and bioinformatic analyses of the small RNA sequence reads identified hundreds of miRNAs among all the treatment groups. A small portion of the identified miRNAs was differentially expressed within each of the four treatment groups, which were HVT or CVI988/Rispens vaccinated line 63-resistant birds and line 72-susceptible birds. A direct comparison between the resistant line 63 and susceptible line 72 groups vaccinated with HVT followed by MDV challenge identified five differentially expressed miRNAs. Gene Ontology analysis of the target genes of those five miRNAs revealed that those target genes, in addition to various GO terms, are involved in multiple signaling pathways including MAPK, TGF-β, ErbB, and EGFR1 signaling pathways. The general functions of those pathways reportedly play important roles in oncogenesis, anti-cancer immunity, cancer cell migration, and metastatic progression. Therefore, it is highly likely that those miRNAs may, in part, influence vaccine protection through the pathways.

Maternal and Paternal Preconception Serum Concentrations of Per and Polyfluoroalkyl Substances in Relation to Birth Outcomes

Prenatal per and polyfluoroalkyl substances (PFAS) exposure is associated with adverse birth outcomes. There is an absence of evidence on the relationship between maternal and paternal preconception PFAS exposure and birth outcomes. This study included 312 mothers and 145 fathers with a singleton live birth from a preconception cohort of subfertile couples seeking fertility treatment at a U.S. clinic. PFAS were quantified in serum samples collected before conception. Gestational age (GA) and birthweight (BW) were abstracted from delivery records. We also assessed low birthweight (BW < 2500 g) and preterm birth (GA < 37 completed weeks). We utilized multivariable linear regression, logistic regression, and quantile-based g computation to examine maternal or paternal serum concentrations of individual PFAS and mixture with birth outcomes. Maternal serum concentrations of perfluorooctanesulfonate (PFOS), perfluorohexanesulfonate (PFHxS), and the total PFAS mixture were inversely associated with birthweight. Maternal PFOS concentration was associated with a higher risk of low birthweight. Conversely, paternal PFOS and PFHxS concentrations were imprecisely associated with higher birthweight. No associations were found for gestational age or preterm birth. The findings have important implications for preconception care. Future research with larger sample sizes would assist in validating these findings.

The role of fathers in child development from preconception to postnatal influences: Opportunities for the National Institutes of Health Environmental influences on Child Health Outcomes (ECHO) program

A growing body of literature highlights the important role of paternal health and socioemotional characteristics in child development, from preconception through adolescence. Much of this research addresses the indirect effects of fathers, for instance, their influence on maternal behaviors during the prenatal period or via the relationship with their partner. However, emerging evidence also recognizes the direct role of paternal health and behavior for child health and adjustment across development. This critical review presents evidence of biological and sociocultural influences of fathers on preconception, prenatal, and postnatal contributions to child development. The National Institutes of Health Environmental influences on Child Health Outcomes (ECHO) program incorporates in its central conceptualization the impact of fathers on family and child outcomes. This critical synthesis of the literature focuses on three specific child outcomes in the ECHO program: health outcomes (e.g., obesity), neurodevelopmental outcomes (e.g., emotional, behavioral, psychopathological development), and positive health. We highlight the unique insights gained from the literature to date and provide next steps for future studies on paternal influences.

Frequency, morbidity and equity - the case for increased research on male fertility

Currently, most men with infertility cannot be given an aetiology, which reflects a lack of knowledge around gamete production and how it is affected by genetics and the environment. A failure to recognize the burden of male infertility and its potential as a biomarker for systemic illness exists. The absence of such knowledge results in patients generally being treated as a uniform group, for whom the strategy is to bypass the causality using medically assisted reproduction (MAR) techniques. In doing so, opportunities to prevent co-morbidity are missed and the burden of MAR is shifted to the woman. To advance understanding of men's reproductive health, longitudinal and multi-national centres for data and sample collection are essential. Such programmes must enable an integrated view of the consequences of genetics, epigenetics and environmental factors on fertility and offspring health. Definition and possible amelioration of the consequences of MAR for conceived children are needed. Inherent in this statement is the necessity to promote fertility restoration and/or use the least invasive MAR strategy available. To achieve this aim, protocols must be rigorously tested and the move towards personalized medicine encouraged. Equally, education of the public, governments and clinicians on the frequency and consequences of infertility is needed. Health options, including male contraceptives, must be expanded, and the opportunities encompassed in such investment understood. The pressing questions related to male reproductive health, spanning the spectrum of andrology are identified in the Expert Recommendation.

Single-locus and Haplotype Associations of GRIN2B Gene with Autism Spectrum Disorders and the Demographic and Clinical Characteristics of Patients in Guilan, Iran

Autism spectrum disorders (ASDs) are described as generalized developmental disorders, with an average age of onset of 36 months. Genetic and environmental factors may contribute to this multifactorial disorder. The present study aimed to investigate the association of three GRIN2B polymorphisms, including rs1019385, rs1024893, and rs3764028, with ASDs. Based on the results, there was a significant difference regarding the genotype frequency of rs3764028 polymorphism between the control and case (ASD) groups (P = 0.027). According to the recessive model, this variant was associated with ASDs (P = 0.23). None of the eight haplotype models with frequencies above 0.5 showed significant differences between the case and control groups in terms of allelic frequency. The present results showed that the rs376028 variant was directly related to the phenotypic symptoms of ASDs.

Prenatal paternal anxiety symptoms predict child DHEA levels and internalizing symptoms during adrenarche

Introduction

This study examined (1) whether measures of paternal anxious and depressive symptoms collected prenatally and during a follow-up assessment when the child was in middle childhood, predict child neuroendocrine outcomes, and (2) whether neuroendocrine outcomes are intermediate factors between paternal mental health and child cognitive/behavioral outcomes. Middle childhood coincides with increased autonomy as the child transitions into grade school, and with adrenarche, as the maturing adrenal gland increases secretion of dehydroepiandrosterone (DHEA) and its sulfated metabolite (DHEA-S), hormones that are implicated in corticolimbic development which regulate emotions and cognition.

Methods

Participants were recruited from a subsample of a large prospective birth cohort study (3D study). We conducted a follow-up study when children were 6-8 years old (N = 61 families, 36 boys, 25 girls). Parental symptoms of anxiety, stress and depression were assessed via validated self-report questionnaires: prenatally using an in-house anxiety questionnaire, the Perceived Stress Scale (PSS) and the Center for Epidemiologic Studies Depression (CES-D), and at the follow up, using the Beck Anxiety and Beck Depression Inventories. Children provided salivary hormone samples, and their pituitary gland volume was measured from structural Magnetic Resonance Imaging (MRI) scans. Child behaviors were measured using the Strengths and Difficulties Questionnaire and cognitive outcomes using the WISC-V. Multiple regression analyses were used to test whether paternal mental health symptoms assessed prenatally and during childhood are associated with child neuroendocrine outcomes, adjusting for maternal mental health and child sex. Indirect-effect models assessed whether neuroendocrine factors are important intermediates that link paternal mental health and cognitive/behavioral outcomes.

Results

(1) Fathers' prenatal anxiety symptoms predicted lower DHEA levels in the children, but not pituitary volume. (2) Higher prenatal paternal anxiety symptoms predicted higher child internalizing symptoms via an indirect pathway of lower child DHEA. No associations were detected between paternal anxiety symptoms measured in childhood, and neuroendocrine outcomes. No child sex differences were detected on any measure.

Conclusion

These results highlight the often-overlooked role of paternal factors during pregnancy on child development, suggesting that paternal prenatal anxiety symptoms are associated with child neuroendocrine function and in turn internalizing symptoms that manifest at least up to middle childhood.

Microplastics exposure: implications for human fertility, pregnancy and child health

Plastics found in our everyday environment are becoming an increasing concern for individual and population-level health, and the extent of exposure and potential toxic effects of these contaminants on numerous human organ systems are becoming clear. Microplastics (MPs), tiny plastic particles, appear to have many of the same biological effects as their plastic precursors and have the compounded effect of potential accumulation in different organs. Recently, microplastic accumulation was observed in the human placenta, raising important questions related to the biological effects of these contaminants on the health of pregnancies and offspring. These concerns are particularly heightened considering the developmental origins of health and disease (DOHaD) framework, which postulates that in utero exposure can programme the lifelong health of the offspring. The current review examines the state of knowledge on this topic and highlights important avenues for future investigation.

Paternal and maternal preconception and maternal pregnancy urinary phthalate metabolite and BPA concentrations in relation to child behavior

BACKGROUND

Epidemiologic studies on health effects of parental preconception exposures are limited despite emerging evidence from toxicological studies suggesting that such exposures, including to environmental chemicals, may affect offspring health.

OBJECTIVE

We investigated whether maternal and paternal preconception and maternal pregnancy urinary phthalate metabolite and bisphenol A (BPA) concentrations were associated with child behavior.

METHODS

We analyzed data from the Preconception Environmental exposure And Childhood health Effects (PEACE) Study, an ongoing prospective cohort study of children aged 6-11 years whose parent(s) previously enrolled in the prospective preconception Environment and Reproductive Health (EARTH) study. Using linear mixed models, we estimated covariate-adjusted associations of 11 urinary phthalate metabolite and BPA concentrations collected prior to conception and during pregnancy with Behavioral Assessment System for Children-3 (BASC-3) T-scores (higher scores indicate more problem behaviors).

RESULTS

This analysis included 134 mothers, 87 fathers and 157 children (24 sets of twins); parents were predominantly non-Hispanic white (mothers and fathers86%). Higher maternal preconception or pregnancy monobenzyl phthalate (MBzP) concentrations were related to higher mean externalizing problems T-scores in their children (β = 1.3 per 1-loge unit increase; 95 % CI: -0.2, 2.4 and β = 2.1, 95 % CI: 0.7, 3.6, respectively). Higher maternal preconception monocarboxyoctyl phthalate (MCOP) was suggested to be related to lower mean externalizing problems T-scores (β = -0.9; 95 % CI: -1.8, 0.0). Higher paternal preconception MCOP was suggestively associated with lower internalizing problems (β = -0.9; 95 %CI:-1.9, 0.1) and lower Behavioral Symptoms Index (BSI) T-scores (β = -1.3; 95 % CI: -2.1, -0.4).

CONCLUSION

In this cohort, higher maternal preconception and pregnancy MBzP were associated with worse parent-reported child behavior, while higher maternal and paternal preconception MCOP concentrations were related to lower BASC-3 scores.

A DNA Methylation Perspective on Infertility

Infertility affects a significant number of couples worldwide and its incidence is increasing. While assisted reproductive technologies (ART) have revolutionized the treatment landscape of infertility, a significant number of couples present with an idiopathic cause for their infertility, hindering effective management. Profiling the genome and transcriptome of infertile men and women has revealed abnormal gene expression. Epigenetic modifications, which comprise dynamic processes that can transduce environmental signals into gene expression changes, may explain these findings. Indeed, aberrant DNA methylation has been widely characterized as a cause of abnormal sperm and oocyte gene expression with potentially deleterious consequences on fertilization and pregnancy outcomes. This review aims to provide a concise overview of male and female infertility through the lens of DNA methylation alterations.

Epidemiology of sperm DNA fragmentation in a retrospective cohort of 1191 men

BACKGROUND

The scientific and clinical communities now recognize that sperm DNA integrity is crucial for successful fertilization, good embryo development, and offspring quality of life. Despite the apparent unanimity, this criterion is rarely evaluated in clinical practice. We evaluated the sperm DNA fragmentation index of nearly 1200 sperm samples and its connections based on the patient's age, body mass index, the season of sperm collection, geographical location, medical history, and addictive behaviors.

METHODS

A cohort of 1503 patients who were referred to the Royan Institute between July 2018 and March 2020 was examined. Only 1191 patient records with demographic data, complete semen analysis, and DNA fragmentation index measurements were included in the final cohort. Documents were classified, incorporated into statistical models, and analyzed.

RESULTS

The results confirmed previous findings that the sperm DNA fragmentation index was significantly higher in aging men. The sperm DNA fragmentation index and high DNA stainability levels were significantly higher in spring and summer samples than in those of other seasons. No correlation was found between semen DNA fragmentation index and patient body mass index, although the study cohort was significantly overweight. Contrary to what might be expected, we observed that the sperm DNA fragmentation index was higher in rural than in urban patients. Intriguingly, epileptic patients exhibited significantly higher sperm DNA fragmentation index levels.

DISCUSSION AND CONCLUSION

Age is the factor that is most strongly associated with sperm DNA fragmentation index levels. Our analysis of 1191 samples indicates that between the ages of 19 and 59, the sperm DNA fragmentation index increases by an average of 2% each year. Intriguingly, from an epidemiological perspective, the warm season (spring/summer) is associated with a higher sperm DNA fragmentation index in the study population, possibly due to the deleterious effect of temperature on sperm quality. Some neurological diseases, such as epilepsy, are associated with decreased sperm DNA integrity. This observation could be related to the iatrogenic effects of associated therapies. In the study cohort, body mass index did not appear to be correlated with the DNA fragmentation index.

Epigenetic determinants of reproductive potential augment the predictive ability of the semen analysis

OBJECTIVE

To investigate the power of DNA methylation variability in sperm cells in assessing male fertility potential.

DESIGN

Retrospective cohort.

SETTING

Fertility care centers.

PATIENTS

Male patients seeking infertility treatment and fertile male sperm donors.

INTERVENTION

None.

MAIN OUTCOME MEASURES

Sperm DNA methylation data from 43 fertile sperm donors were analyzed and compared with the data from 1344 men seeking fertility assessment or treatment. Methylation at gene promoters with the least variable methylation in fertile patients was used to create 3 categories of promoter dysregulation in the infertility treatment cohort: poor, average, and excellent sperm quality.

RESULTS

After controlling for female factors, there were significant differences in intrauterine insemination pregnancy and live birth outcomes between the poor and excellent groups across a cumulative average of 2-3 cycles: 19.4% vs. 51.7% (P=.008) and 19.4% vs. 44.8% (P=.03), respectively. Live birth outcomes from in vitro fertilization, primarily with intracytoplasmic sperm injection, were not found to be significantly different among any of the 3 groups.

CONCLUSION

Methylation variability in a panel of 1233 gene promoters could augment the predictive ability of semen analysis and be a reliable biomarker for assessing intrauterine insemination outcomes. In vitro fertilization with intracytoplasmic sperm injection appears to overcome high levels of epigenetic instability in sperm.

Association of Overweight and Obesity with Semen Parameters and Metabolic and Hormonal Status in Young Men

We evaluated possible associations of overweight and obesity with semen parameters, sperm DNA fragmentation (SDF), and different indicators of metabolic and hormonal status in young men (n=226, mean age 22.5 years). Overweight and obese men were found to have a significant deterioration of metabolic health, reduced total sperm count and concentration, serum testosterone, and inhibin B levels, and increased serum leptin and seminal zinc levels in comparison with men with normal weight, although sperm DNA fragmentation, motility, and morphology did not change. In overweight and obese men, increased seminal zinc content appears to perform a protective function via reduction of oxidative stress caused by excess body fat. It is assumed that in the absence of individual lifestyle correction and weight loss for a long time, obese subjects are not protected from the development of reproductive comorbidities, in particular, subfertility and infertility.

Optimizing preconception care and interventions for improved population health

There is growing literature indicating that optimal preconception health is associated with improved reproductive, perinatal, and pediatric outcomes. Given that preconception care is recommended for all individuals planning a pregnancy, medical providers and public health practitioners have a unique opportunity to optimize care and improve health outcomes for reproductive-aged individuals. Knowledge of the determinants of preconception health is important for all types of health professionals, including policy makers. Although some evidence-based recommendations have already been implemented, additional research is needed to identify factors associated with favorable health outcomes and to ensure that effective interventions are made in a timely fashion. Given the largely clinical readership of this journal, this piece is primarily focused on clinical care. However, we acknowledge that optimizing preconception health for the entire population at risk of pregnancy requires broadening our strategies to include population-health interventions that consider the larger social systems, structures, and policies that shape individual health outcomes.

Paternal effects on fetal programming

Paternal programming is the concept that the environmental signals from the sire's experiences leading up to mating can alter semen and ultimately affect the phenotype of resulting offspring. Potential mechanisms carrying the paternal effects to offspring can be associated with epigenetic signatures (DNA methylation, histone modification and non-coding RNAs), oxidative stress, cytokines, and the seminal microbiome. Several opportunities exist for sperm/semen to be influenced during development; these opportunities are within the testicle, the epididymis, or accessory sex glands. Epigenetic signatures of sperm can be impacted during the pre-natal and pre-pubertal periods, during sexual maturity and with advancing sire age. Sperm are susceptible to alterations as dictated by their developmental stage at the time of the perturbation, and sperm and seminal plasma likely have both dependent and independent effects on offspring. Research using rodent models has revealed that many factors including over/under nutrition, dietary fat, protein, and ingredient composition (e.g., macro- or micronutrients), stress, exercise, and exposure to drugs, alcohol, and endocrine disruptors all elicit paternal programming responses that are evident in offspring phenotype. Research using livestock species has also revealed that sire age, fertility level, plane of nutrition, and heat stress can induce alterations in the epigenetic, oxidative stress, cytokine, and microbiome profiles of sperm and/or seminal plasma. In addition, recent findings in pigs, sheep, and cattle have indicated programming effects in blastocysts post-fertilization with some continuing into post-natal life of the offspring. Our research group is focused on understanding the effects of common management scenarios of plane of nutrition and growth rates in bulls and rams on mechanisms resulting in paternal programming and subsequent offspring outcomes. Understanding the implication of paternal programming is imperative as short-term feeding and management decisions have the potential to impact productivity and profitability of our herds for generations to come.

Does the father's job matter? Parental occupation and preterm birth in Korea

OBJECTIVES

Limited evidence is available regarding the impact of paternal occupation and its combined effect with maternal occupation on preterm birth. Therefore, we assessed the association of maternal and paternal occupations with preterm birth.

METHODS

We used the national birth data of Korea between 2010 and 2020. Parental occupations were divided into 5 categories: (1) managers; (2) professionals, technicians, and related workers; (3) clerks and support workers; (4) service and sales workers; and (5) manual workers. A multinomial logistic regression model was used to calculate the adjusted odds ratios (aORs) of extremely, very, and moderate-to-late preterm births per occupational category considering individual risk factors.

RESULTS

For the 4,004,976 singleton births, 40.2% of mothers and 95.5% of fathers were employed. Compared to non-employment, employment was associated with a lower risk of preterm birth. Among employed mothers, service and sales occupations were associated with a higher risk of preterm birth than managerial occupations (aOR, 1.06; 95% confidence interval [CI], 1.01 to 1.10 for moderate-to-late preterm births). The father's manual occupation was associated with a higher risk of preterm birth (aOR, 1.09; 95% CI, 1.05 to 1.13 for moderate-to-late preterm) than managerial occupations. When both parents had high-risk occupations, the risk of preterm birth was higher than in cases where only the mother or neither of the parents had a high-risk occupation.

CONCLUSIONS

Paternal occupation was associated with preterm birth regardless of maternal employment and occupation and modified the effect of maternal occupation. Detailed occupational environment data are needed to identify the paternal exposures that increase the risk.

AHR-mediated m6A RNA methylation contributes to PM2.5-induced cardiac malformations in zebrafish larvae

A growing body of evidence indicates that ambient fine particle matter (PM_2.5) exposure inhibits heart development, but the underlying mechanisms remain elusive. We hypothesized that m⁶A RNA methylation plays an important role in the cardiac developmental toxicity of PM_2.5. In this study, we demonstrated that extractable organic matter (EOM) from PM2.5 significantly decreased global m⁶A RNA methylation levels in the heart of zebrafish larvae, which were restored by the methyl donor, betaine. Betaine also attenuated EOM-induced ROS overgeneration, mitochondrial damage, apoptosis and heart defects. Furthermore, we found that the aryl hydrocarbon receptor (AHR), which was activated by EOM_, directly repressed the transcription of methyltransferases mettl14 and mettl3. EOM also induced genome-wide m⁶A RNA methylation changes, which led us to focus more on the aberrant m⁶A methylation changes that were subsequently alleviated by the AHR inhibitor, CH223191. In addition, we found that the expression levels of traf4a and bbc3, two apoptosis related genes, were upregulated by EOM but restored to control levels by the forced expression of mettl14. Moreover, knockdown of either traf4a or bbc3 attenuated EOM-induced ROS overproduction and apoptosis. In conclusion, our results indicate that PM_2.5 induces m⁶A RNA methylation changes via AHR-mediated mettl14 downregulation, which upregulates traf4a and bbc3, leading to apoptosis and cardiac malformations.

Epigenetic markers in the embryonal germ cell development and spermatogenesis

Spermatogenesis is the process of generation of male reproductive cells from spermatogonial stem cells in the seminiferous epithelium of the testis. During spermatogenesis, key spermatogenic events such as stem cell self-renewal and commitment to meiosis, meiotic recombination, meiotic sex chromosome inactivation, followed by cellular and chromatin remodeling of elongating spermatids occur, leading to sperm cell production. All the mentioned events are at least partially controlled by the epigenetic modifications of DNA and histones. Additionally, during embryonal development in primordial germ cells, global epigenetic reprogramming of DNA occurs. In this review, we summarized the most important epigenetic modifications in the particular stages of germ cell development, in DNA and histone proteins, starting from primordial germ cells, during embryonal development, and ending with histone-to-protamine transition during spermiogenesis.

Approaches for sRNA Analysis of Human RNA-Seq Data: Comparison, Benchmarking

Expression analysis of small noncoding RNA (sRNA), including microRNA, piwi-interacting RNA, small rRNA-derived RNA, and tRNA-derived small RNA, is a novel and quickly developing field. Despite a range of proposed approaches, selecting and adapting a particular pipeline for transcriptomic analysis of sRNA remains a challenge. This paper focuses on the identification of the optimal pipeline configurations for each step of human sRNA analysis, including reads trimming, filtering, mapping, transcript abundance quantification and differential expression analysis. Based on our study, we suggest the following parameters for the analysis of human sRNA in relation to categorical analyses with two groups of biosamples: (1) trimming with the lower length bound = 15 and the upper length bound = Read length - 40% Adapter length; (2) mapping on a reference genome with bowtie aligner with one mismatch allowed (-v 1 parameter); (3) filtering by mean threshold > 5; (4) analyzing differential expression with DESeq2 with adjusted p-value < 0.05 or limma with p-value < 0.05 if there is very little signal and few transcripts.

Assessing testicular germ cell DNA damage in the comet assay; introduction of a proof-of-concept

The in vivo comet assay is widely used to measure genotoxicity; however, the current OECD test guideline (TG 489) does not recommend using the assay to assess testicular germ cells, due to the presence of testicular somatic cells. An adapted approach to specifically assess testicular germ cells within the comet assay is certainly warranted, considering regulatory needs for germ cell-specific genotoxicity data in relation to the increasing global production of and exposure to potentially hazardous chemicals. Here, we provide a proof-of-concept to selectively analyze round spermatids and primary spermatocytes, distinguishing them from other cells of the testicle. Utilizing the comet assay recordings of DNA content (total fluorescence intensity) and DNA damage (% tail intensity) of individual comets, we developed a framework to distinguish testicular cell populations based on differences in DNA content/ploidy and appearance. Haploid round spermatid comets are identified through (1) visual inspection of DNA content distributions, (2) setting DNA content thresholds, and (3) modeling DNA content distributions using a normal mixture distribution function. We also describe an approach to distinguish primary spermatocytes during comet scoring, based on their high DNA content and large physical size. Our concept allows both somatic and germ cells to be analyzed in the same animal, adding a versatile, sensitive, rapid, and resource-efficient assay to the limited genotoxicity assessment toolbox for germ cells. An adaptation of TG 489 facilitates accumulation of valuable information regarding distribution of substances to germ cells and their potential for inducing germ cell gene mutations and structural chromosomal aberrations.

Trimester-specific ambient PM2.5 exposures and risk of intellectual disability in Utah

Prenatal fine particulate matter (PM2.5) exposure is an understudied risk factor for neurodevelopmental outcomes, including intellectual disability (ID). Associations among prenatal exposures and neurodevelopmental outcomes may vary depending on the timing of exposure. Limited numbers of studies examining PM2.5 and neurodevelopmental outcomes have considered exposures occurring during the preconception period. To address these gaps, we conducted a case-control study of children born in Utah between 2002 and 2008 (n = 1032). Cases were identified using methods developed by the Centers for Disease Control and Prevention's Autism and Developmental Disabilities Monitoring Network and matched with controls on birth year, sex, and birth county. We estimated the daily average PM2.5 concentration during a period spanning 12 weeks before the estimated conception date, as well as during each of the three trimesters at the maternal residential address listed on the child's birth certificate. In a multivariable model, the third (OR: 2.119, CI: 1.123-3.998, p = .021) and fourth (OR: 2.631, CI: 1.750-3.956, p < .001) quartiles for preconception average PM2.5 demonstrated significantly increased risk of ID relative to the first quartile. Second quartile preconception exposure was also associated with increased risk, though it did not reach significance (OR: 1.385, CI: 0.979-1.959, p = .07). The fourth quartile of first trimester average PM2.5 was positive and significant (OR: 2.278, CI: 1.522-3.411, p < .001); the third quartile was positive, but not significant (OR: 1.159, CI: 0.870-1.544, p = .312). Quartiles of second and third trimester were not associated with higher risk of ID. These findings from Utah, which were robust to a variety of sensitivity analyses, provide initial evidence that preconception and prenatal PM2.5 exposure may be associated with ID. Future studies are needed across other geographic locations and populations.

Phthalates impact on the epigenetic factors contributed specifically by the father at fertilization

BACKGROUND

Preconception exposure to phthalates such as the anti-androgenic dibutyl-phthalate (DBP) impacts both male and female reproduction, yet how this occurs largely remains unknown. Previously we defined a series of RNAs expressly provided by sperm at fertilization and separately, and in parallel, those that responded to high DBP exposure. Utilizing both populations of RNAs, we now begin to unravel the impact of high-DBP exposure on those RNAs specifically delivered by the father.

RESULTS

Enrichment of RNAs altered by DBP exposure within the Molecular Signature Database highlighted cellular stress, cell cycle, apoptosis, DNA damage response, and gene regulation pathways. Overlap within each of these five pathways identified those RNAs that were specifically (≥ fivefold enriched) or primarily (≥ twofold enriched) provided as part of the paternal contribution compared to the oocyte at fertilization. Key RNAs consistently altered by DBP, including CAMTA2 and PSME4, were delivered by sperm reflective of these pathways. The majority (64/103) of overlapping enriched gene sets were related to gene regulation. Many of these RNAs (45 RNAs) corresponded to key interconnected CRREWs (Chromatin remodeler cofactors, RNA interactors, Readers, Erasers, and Writers). Modeling suggests that CUL2, PHF10, and SMARCC1 may coordinate and mechanistically modulate the phthalate response.

CONCLUSIONS

Mediated through a CRREW regulatory network, the cell responded to exposure presenting stressed-induced changes in the cell cycle-DNA damage-apoptosis. Interestingly, the majority of these DBP-responsive epigenetic mediators' direct acetylation or deacetylation, impacting the sperm's cargo delivered at fertilization and that of the embryo.

Lifestyle interventions to reduce endocrine-disrupting phthalate and phenol exposures among reproductive age men and women: A review and future steps

Non-persistent endocrine-disrupting chemicals (EDCs), including phthalates and phenols, are ubiquitous in both the environment and human body. A growing body of epidemiologic studies have identified concerning links between EDCs and adverse reproductive and developmental health effects. Despite consistent evidence, risk assessments and policy interventions often arrive late. This presents an urgent need to identify evidence-based interventions for implementation at both clinical and community levels to reduce EDC exposure, especially in susceptible populations. The reproductive life cycle (menarche to menopause for females and after pubertal onset for males) includes some of the most vulnerable periods to environmental exposures, such as the preconception and perinatal stages, representing a key window of opportunity to intervene and prevent unfavorable health outcomes. This review aims to synthesize and assess behavioral, dietary, and residential EDC-driven interventions to develop recommendations for subsequent, larger-scale studies that address knowledge-gaps in current interventions during the reproductive life cycle. We selected 21 primary interventions for evaluation, in addition to four supplemental interventions. Among these, accessible (web-based) educational resources, targeted replacement of (known) toxic products, and personalization of the intervention through meetings and support groups, were the most promising strategies for reducing EDC concentrations. However, we document a paucity of interventions to prevent phthalate and phenol exposures during the reproductive years, especially among men. Accordingly, we recommend additional, larger clinical and community-based intervention studies to reduce EDC exposure. Specifically, future intervention studies should focus on short-term, mid-, and long-term exposure reduction to phthalates and phenols. The latter, especially, is required for the development of clinical and public health guidelines to promote reproductive and developmental health globally.

What is the importance of sperm subpopulations?

The study of sperm subpopulations spans three decades. The origin, meaning, and practical significance, however, are less clear. Current technology for assessing sperm morphology (CASA-Morph) and motility (CASA-Mot) has enabled the accurate evaluation of these features, and there are many options for data classification. Subpopulations could occur as a result of the stage of development of each spermatozoon in the subpopulation. Spermatogenesis might contribute to the production of these subpopulations. Insights from evolutionary biology and recent molecular research are indicative of the diversity among male gametes that could occur from unequal sharing of transcripts and other elements through cytoplasmic bridges between spermatids. Sperm cohorts exiting the gonads would contain different RNA and protein contents, affecting the spermatozoon physiology and associations with the surrounding environmental milieu. Subsequently, these differences could affect how spermatozoa interact with the environmental milieu (maturation, mixing with seminal plasma, and interacting with the environmental milieu, or female genital tract and female gamete). The emergence of sperm subpopulations as an outcome of evolution, related to the reproductive strategies of the species, genital tract structures, and copulatory and fertilization processes. This kind of approach in determining the importance of sperm subpopulations in fertilization capacity should have a practical impact for conducting reproductive technologies, inspiring and enabling new ways for the more efficient use of spermatozoa in the medical, animal breeding, and conservation fields. This manuscript is a contribution to the Special Issue in memory of Dr. Duane Garner.

The influence of parental body composition and lifestyle on offspring growth trajectories

BACKGROUND AND OBJECTIVES

Parental body composition, physical activity (PA) and sedentary time (ST) have been linked with offspring body weight and health. However, independent contributions of body composition, PA and ST of both parents on growth trajectories of their offspring, taking into account sex differences, has not been investigated.

METHODS

A total of 114 mother-father-child triads were included for analyses. Parental weight, height, PA and ST were objectively measured at 12 weeks of gestation. Gestational weight gain (GWG) and birthweight and -length were obtained from medical records. Offspring weight and length were measured repeatedly until 1 year of age. Longitudinal linear mixed models, stratified by offspring sex, were used to analyse the association between parental characteristics and offspring growth.

RESULTS

GWG (positive association), maternal moderate-to-vigorous PA (negative association) and paternal ST (positive association) were associated with weight trajectories in girls but not in boys. Parental characteristics were not associated with offspring length trajectories.

CONCLUSIONS

This study highlights the contribution of parental lifestyle characteristics on weight trajectories of their daughters during the first year of life. The paternal impact stresses the need to further investigate health behaviours of expecting fathers in relation to offspring health. Family-based interventions are needed with a focus on increasing PA and limiting ST in both parents.

Parental Programming of Offspring Health: The Intricate Interplay between Diet, Environment, Reproduction and Development

As adults, our health can be influenced by a range of lifestyle and environmental factors, increasing the risk for developing a series of non-communicable diseases such as type 2 diabetes, heart disease and obesity. Over the past few decades, our understanding of how our adult health can be shaped by events occurring before birth has developed into a well-supported concept, the Developmental Origins of Health and Disease (DOHaD). Supported by epidemiological data and experimental studies, specific mechanisms have been defined linking environmental perturbations, disrupted fetal and neonatal development and adult ill-health. Originally, such studies focused on the significance of poor maternal health during pregnancy. However, the role of the father in directing the development and well-being of his offspring has come into recent focus. Whereas these studies identify the individual role of each parent in shaping the long-term health of their offspring, few studies have explored the combined influences of both parents on offspring well-being. Such understanding is necessary as parental influences on offspring development extend beyond the direct genetic contributions from the sperm and oocyte. This article reviews our current understanding of the parental contribution to offspring health, exploring some of the mechanisms linking parental well-being with gamete quality, embryo development and offspring health.

Age-associated epigenetic changes in mammalian sperm: implications for offspring health and development

BACKGROUND

Modern reproductive behavior in most developed countries is characterized by delayed parenthood. Older gametes are generally less fertile, accumulating and compounding the effects of varied environmental exposures that are modified by lifestyle factors. Clinicians are primarily concerned with advanced maternal age, while the influence of paternal age on fertility, early development and offspring health remains underappreciated. There is a growing trend to use assisted reproductive technologies for couples of advanced reproductive age. Thus, the number of children born from older gametes is increasing.

OBJECTIVE AND RATIONALE

We review studies reporting age-associated epigenetic changes in mammals and humans in sperm, including DNA methylation, histone modifications and non-coding RNAs. The interplay between environment, fertility, ART and age-related epigenetic signatures is explored. We focus on the association of sperm epigenetics on epigenetic and phenotype events in embryos and offspring.

SEARCH METHODS

Peer-reviewed original and review articles over the last two decades were selected using PubMed and the Web of Science for this narrative review. Searches were performed by adopting the two groups of main terms. The first group included 'advanced paternal age', 'paternal age', 'postponed fatherhood', 'late fatherhood', 'old fatherhood' and the second group included 'sperm epigenetics', 'sperm', 'semen', 'epigenetic', 'inheritance', 'DNA methylation', 'chromatin', 'non-coding RNA', 'assisted reproduction', 'epigenetic clock'.

OUTCOMES

Age is a powerful factor in humans and rodent models associated with increased de novo mutations and a modified sperm epigenome. Age affects all known epigenetic mechanisms, including DNA methylation, histone modifications and profiles of small non-coding (snc)RNA. While DNA methylation is the most investigated, there is a controversy about the direction of age-dependent changes in differentially hypo- or hypermethylated regions with advanced age. Successful development of the human sperm epigenetic clock based on cross-sectional data and four different methods for DNA methylation analysis indicates that at least some CpG exhibit a linear relationship between methylation levels and age. Rodent studies show a significant overlap between genes regulated through age-dependent differentially methylated regions and genes targeted by age-dependent sncRNA. Both age-dependent epigenetic mechanisms target gene networks enriched for embryo developmental, neurodevelopmental, growth and metabolic pathways. Thus, age-dependent changes in the sperm epigenome cannot be described as a stochastic accumulation of random epimutations and may be linked with autism spectrum disorders. Chemical and lifestyle exposures and ART techniques may affect the epigenetic aging of sperm. Although most epigenetic modifications are erased in the early mammalian embryo, there is growing evidence that an altered offspring epigenome and phenotype is linked with advanced paternal age due to the father's sperm accumulating epigenetic changes with time. It has been hypothesized that age-induced changes in the sperm epigenome are profound, physiological and dynamic over years, yet stable over days and months, and likely irreversible.

WIDER IMPLICATIONS

This review raises a concern about delayed fatherhood and age-associated changes in the sperm epigenome that may compromise reproductive health of fathers and transfer altered epigenetic information to subsequent generations. Prospective studies using healthy males that consider confounders are recommended. We suggest a broader discussion focused on regulation of the father's age in natural and ART conceptions is needed. The professional community should be informed and should raise awareness in the population and when counseling older men.

Sperm epigenetic clock associates with pregnancy outcomes in the general population

STUDY QUESTION

Is sperm epigenetic aging (SEA) associated with probability of pregnancy among couples in the general population?

SUMMARY ANSWER

We 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 ALREADY

The 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, DURATION

This 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, METHODS

Sperm 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 CHANCE

Our 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 CAUTION

This 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 FINDINGS

These 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 NUMBER

N/A.

Innate Immunity: A Balance between Disease and Adaption to Stress

Since first being documented in ancient times, the relation of inflammation with injury and disease has evolved in complexity and causality. Early observations supported a cause (injury) and effect (inflammation) relationship, but the number of pathologies linked to chronic inflammation suggests that inflammation itself acts as a potent promoter of injury and disease. Additionally, results from studies over the last 25 years point to chronic inflammation and innate immune signaling as a critical link between stress (exogenous and endogenous) and adaptation. This brief review looks to highlight the role of the innate immune response in disease pathology, and recent findings indicating the innate immune response to chronic stresses as an influence in driving adaptation.

Effect of Paternal Diet on Spermatogenesis and Offspring Health: Focus on Epigenetics and Interventions with Food Bioactive Compounds

Infertility is a growing public health problem. Consumption of antioxidant bioactive food compounds (BFCs) that include micronutrients and non-nutrients has been highlighted as a potential strategy to protect against oxidative and inflammatory damage in the male reproductive system induced by obesity, alcohol, and toxicants and, thus, improve spermatogenesis and the fertility parameters. Paternal consumption of such dietary compounds could not only benefit the fathers but their offspring as well. Studies in the new field of paternal origins of health and disease show that paternal malnutrition can alter sperm epigenome, and this can alter fetal development and program an increased risk of metabolic diseases and breast cancer in adulthood. BFCs, such as ascorbic acid, α-tocopherol, polyunsaturated fatty acids, trace elements, carnitines, N-acetylcysteine, and coenzyme Q10, have been shown to improve male gametogenesis, modulate epigenetics of germ cells, and the epigenetic signature of the offspring, restoring offspring metabolic health induced by stressors during early life. This indicates that, from a father’s perspective, preconception is a valuable window of opportunity to start potential nutritional interventions with these BFCs to maximize sperm epigenetic integrity and promote adequate fetal growth and development, thus preventing chronic disease in adulthood.

Exposure of Preconception Couples to Legacy and Emerging Per- and Polyfluoroalkyl Substances: Variations Within and Between Couples

Exploration of the exposure of preconception couples to per- and polyfluoroalkyl substances (PFAS), as well as the most important influencing factors, promotes the understanding of the joint effects of parental exposure on reproductive health. In the present study, a total of 938 preconception couples recruited through the Shanghai Birth Cohort were investigated for the variations of PFAS exposure and contributing factors within and between couples. While linear perfluorooctanoic acid (n-PFOA, median 20.4 ng/mL) and linear perfluorooctanesulfonic acid (n-PFOS, 12.1 ng/mL) remained dominant in plasma, emerging PFAS, particularly 6:2 chlorinated polyfluorinated ether sulfonate (10.5 ng/mL), 6:2 polyfluoroalkyl phosphate diester (0.41 ng/mL), and branched PFOS or PFOA isomers, were also frequently detected. Although individual PFAS were generally correlated within couples, gender differences significantly existed in the concentrations of most individual PFAS and isomer profiles of PFOS and PFOA. Men generally exhibited higher plasma concentrations than their partners, likely reflecting gender-specific elimination pathway and kinetics. Couple-based PFAS exposure also varied greatly. After adjustment for individual factors, several household factors, including annual household income, dwelling floor type, drinking water source, and living near farmlands, were found to be associated with couple-based PFAS exposure. Our study constitutes one of the few studies addressing couple-based exposure to PFAS and lays a solid ground for further assessment of the impacts of parental exposure on reproductive health.

ITAS: Integrated Transcript Annotation for Small RNA

Transcriptomics analysis of various small RNA (sRNA) biotypes is a new and rapidly developing field. Annotations for microRNAs, tRNAs, piRNAs and rRNAs contain information on transcript sequences and loci that is vital for downstream analyses. Several databases have been established to provide this type of data for specific RNA biotypes. However, these sources often contain data in different formats, which makes the bulk analysis of several sRNA biotypes in a single pipeline challenging. Information on some transcripts may be incomplete or conflicting with other entries. To overcome these challenges, we introduce ITAS, or Integrated Transcript Annotation for Small RNA, a filtered, corrected and integrated transcript annotation containing information on several types of small RNAs, including tRNA-derived small RNA, for several species (Homo sapiens, Rattus norvegicus, Mus musculus, Drosophila melanogaster, Caenorhabditis elegans). ITAS is presented in a format applicable for the vast majority of bioinformatic transcriptomics analysis, and it was tested in several case studies for human-derived data against existing alternative databases.