Condensation and protamination of sperm chromatin affect ICSI outcomes when gametes from healthy individuals are used.

STUDY QUESTION: Do defects in sperm chromatin protamination and condensation have an impact on ICSI outcomes? SUMMARY ANSWER: Sperm protamination is related to fertilization rates in healthy donors, and the in vitro capacity of sperm to condense their chromatin is linked to blastocyst rates, both associations being more apparent in women <33 years of age. WHAT IS KNOWN ALREADY: Previous data on how sperm chromatin damage affects ICSI outcomes are inconsistent. Revealing which sperm factors influence embryo development is necessary to understand the male contribution to ICSI success and to develop novel sperm selection techniques or male-based treatments. Sperm chromatin is mainly condensed in protamines, which are cross-linked through disulphide bridges. This study aimed to determine whether sperm protamination and the integrity of disulphide bonds (condensation) are related to embryo development after ICSI. STUDY DESIGN, SIZE, DURATION: The design was a retrospective study with a blind analysis of sperm chromatin. Gametes were divided into two groups: double donation (DD) cohort and single donation (SD) cohort. Samples from 45 semen donors used in 55 ICSI cycles with oocyte donors (age range 19-33 years), generating 491 embryos, were included in the DD cohort. The SD cohort consisted of samples from 34 semen donors used in 41 ICSI cycles with oocytes from healthy females (single-parent families or lesbian couples, age range 20-44 years), generating a total of 378 embryos. PARTICIPANTS/MATERIALS, SETTINGS, METHODS: Donor sperm samples from DD and SD cohorts were used for standard ICSI, and embryo development was observed by time-lapse imaging. The incidence of thiol reduction (dibromobimane, DBB) and the degree of chromatin protamination (chromomycin A3, CMA3, indicating non-protaminated regions) in sperm were determined by flow cytometry at 0 and 4 h post-thawing. MAIN RESULTS AND THE ROLE OF CHANCE: Percentages ± standard deviation of CMA3 were 21.08 ± 9.09 and 35.01 ± 14.68 at 0 and 4 h post-thawing, respectively, in the DD cohort and 22.57 ± 9.48 and 35.79 ± 12.58, at 0 and 4 h post-thawing, respectively, in the SD cohort. Percentages of DBB+ were 16.57 ± 11.10 and 10.51 ± 8.40 at 0 and 4 h post-thawing (P < 0.0001), respectively, in the DD cohort and 17.98 ± 10.19 and 12.72 ± 8.76 at 0 and 4 h post-thawing (P < 0.0001), respectively, in the SD cohort. Female age correlated with fertilization rates, and the relation between sperm chromatin and embryo development was determined through multiple linear regression. While CMA3 was associated with fertilization rates, with no influence of female age, in the DD cohort (ß1 = -1.036, P < 0.001 for CMA3; ß2 = 0.667, P = 0.304 for female age), this was not observed in the SD cohort, where female age had a significant effect, masking the effects of CMA3 (ß1 = -0.066, P = 0.804 for CMA3; ß 2 = -1.451, P = 0.003 for female age). The in vitro capacity of sperm to condense their chromatin after 4 h of incubation was associated with blastocyst rates, independent of female age (DD cohort: ß1 = -0.238, P = 0.008 for %DBB+ variation; ß2 = 0.404, P = 0.638 for female age; SD cohort: ß1 = -0.278, P = 0.010 for %DBB+ variation; ß2 = -0.292, P = 0.594 for female age). The in vitro capacity of sperm to condense their chromatin was also related to the time required for the embryo to reach blastocyst stage in the DD cohort (P = 0.007). Finally, multiple logistic regression showed that both chromatin protamination and condensation, together with the age of the oocyte donors and the embryo recipients, had an impact on pregnancy achievement (P < 0.01) and on live birth rates (P < 0.01). LIMITATIONS, REASONS FOR CAUTION: The main limitation was the restrictive selection of couples, which led to a relatively small sample size and could influence the observed outcomes. For this reason, and to reduce Type I error, the level of significance was set at P ≤ 0.01. On the other hand, the use of cryopreserved samples could also be a limitation. WIDER IMPLICATIONS OF THE FINDINGS: This research demonstrated that protamination and condensation of sperm chromatin are related to embryo development after ICSI, but female age could be a confounding factor when oocytes from older females are used. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by the European Union's Horizon 2020 Research and Innovation scheme under the Marie Sklodowska-Curie grant agreement No 801342 (Tecniospring INDUSTRY; TECSPR-19-1-0003); La Marató de TV3 Foundation (214/857-202039); the Ministry of Science and Innovation, Spain (IJC2019-039615-I); the Catalan Agency for Management of University and Research Grants, Regional Government of Catalonia, Spain (2017-SGR-1229); and the Catalan Institution for Research and Advanced Studies, Spain (ICREA). The authors declare no competing interests. TRIAL REGISTRATION NUMBER: N/A.

Exploring the Occurrence of Organic Contaminants in Human Semen through an Innovative LC-HRMS-Based Methodology Suitable for Target and Nontarget Analysis.

Understanding the potential impact of organic contaminants on male fertility is crucial, yet limited studies have examined these chemicals in semen, with most focusing on urine and blood. To address this gap, we developed and validated a robust LC-HRMS methodology for semen analysis, with a focus on polar and semipolar chemicals. Our methodology enables the quantitative (or semiquantitative) analysis of >2000 chemicals being compatible with suspect and nontarget strategies and providing unprecedented insights into the occurrence and potential bioaccumulation of diverse contaminants in this matrix. We comprehensively analyzed exogenous organic chemicals and associated metabolites in ten semen samples from Spanish participants collected in an area with a large presence of the chemical industry included in the LED-FERTYL Spanish study cohort. This investigation revealed the presence of various contaminants in semen, including plastic additives, PFAS, flame retardants, surfactants, and insecticides. Notably, prevalent plastic additives such as phthalic acid esters and bisphenols were identified, indicating potential health risks. Additionally, we uncovered previously understudied chemicals like the tire additive 2-mercaptobenzothiazole and specific organophosphate flame retardants. This study showcases the potential of our methodology as a valuable tool for large-scale cohort studies, providing insights into the association between contaminant exposure and the risk of male fertility impairments.

Lack of association between endocrine disrupting chemicals and male fertility: A systematic review and meta-analysis.

The incidence of infertility currently affects about 15% of the world's population. Male factors are estimated to be responsible for up to 40-50% of these cases. While the cause of these reproductive disorders is still unclear, the exposure to a family of ubiquitous compounds in our daily life, named endocrine disrupting chemicals (EDCs) could be involved. This paper was aimed at performing a systematic review and meta-analysis of population studies exploring whether human male exposure to EDCs affects male fertility. Clinical and observational studies assessing the exposure to EDCs along with sperm quality, the most common reproductive disorders, sperm DNA damage, sperm oxidative stress, fertilization rate, implantation rate, clinical pregnancy rate, live birth rate, and miscarriage rate were included. The quality assessment tool from the NHLBI-NIH was used to assure that studies met standardized quality criteria. Sensitivity analysis and heterogeneity among studies was assessed. Overall, the 32 selected articles, including 7825 individuals in the systematic review, explored 12 families of EDCs. The results revealed a high heterogeneity among studies in relation to the association between exposure to EDCs and the endpoints analyzed. Meta-analyses were performed with data from 7 articles including 479 individuals, 4 articles assessing the association between BPA in urine and sperm quality, and 3 articles evaluating PCB153 in serum and sperm quality. In the meta-analysis, we identified an unpredicted significant positive association between PCB153 exposure and sperm concentration. However, it would not be clinically relevant. No positive or inverse associations were found neither for BPA, nor for PCB153 and the rest of sperm parameters analyzed. The high disparity between studies made difficult to draw conclusions on the potential harmful effects of EDCs on male fertility. Consequently, to delineate the potential relationship that EDCs can have on male fertility, an important condition stressing the health system, further investigations are required.

Women's and men's intake of omega-3 fatty acids and their food sources and assisted reproductive technology outcomes.

BACKGROUND: Long-chain omega-3 fatty acids and their food sources have garnered interest as a potential nutrient with wide-range health benefits, including fertility. OBJECTIVE: This study aimed to investigate the association of women's and men's intake of omega-3 fatty acids and omega-3 rich-foods with semen quality and outcomes of infertility treatment with assisted reproductive technologies. STUDY DESIGN: Couples presenting to the Massachusetts General Hospital were invited to enroll in a prospective cohort study (2007-2020). Male and female diets were assessed using a validated 131-item food frequency questionnaire. The primary outcomes were implantation, clinical pregnancy, and live birth probabilities. The secondary outcomes included total and clinical pregnancy loss and conventional semen parameters, for males only. We estimated the relationship between intakes of omega-3 fatty acids, nuts, and fish and the probability (95% confidence interval) of study outcomes using generalized linear mixed models to account for repeated treatment cycles per participant while simultaneously adjusting for age, body mass index, smoking status, education, dietary patterns, total energy intake, and male partner diet. RESULTS: A total of 229 couples and 410 assisted reproductive technology cycles were analyzed for primary and secondary outcomes. Of note, 343 men contributing 896 semen samples were included in analyses for semen quality measures. Women's docosahexaenoic acid + eicosapentaenoic acid intake was positively associated with live birth. The multivariable-adjusted probabilities of live birth for women in the bottom and top quartiles of eicosapentaenoic acid + docosahexaenoic acid intake were 0.36 (95% confidence interval, 0.26-0.48) and 0.54 (95% confidence interval, 0.42-0.66) (P trend=.02). Eicosapentaenoic acid + docosahexaenoic acid intake was inversely related to the risk of pregnancy loss, which was 0.53 among women in the lowest quartile of eicosapentaenoic acid + docosahexaenoic acid intake and 0.05 among women in the highest quartile (P trend=.01). Men's intake of total omega-3 fatty acids was positively related to sperm count, concentration, and motility, but unrelated to any assisted reproductive technology outcomes. Similar associations were observed when evaluating the intake of primary food sources of these fatty acids. CONCLUSION: Women's consumption of omega-3 fatty acids and omega-3-rich foods may improve the probability of conception by decreasing the risk of pregnancy loss. In addition, men's intake of omega-3 fatty acids may influence semen quality.

Involvement of extracellular vesicle-encapsulated miRNAs in human reproductive disorders: a systematic review.

In recent years, extracellular vesicles (EVs) have emerged as essential players in cell-to-cell communication, particularly having an active regulating role in biological systems. Because reproductive-associated processes are not exempt of this communication, multiple studies have been devoted to this realm, focusing on gamete maturation, embryo implantation or fetal development. The aim of the present review was to comprehensively and systematically collect evidence about the function of the microRNA (miRNA) encapsulated in EVs isolated from different reproductive tissues or fluids in reproductive-related diseases. Following PRISMA guidelines, we conducted a systematic search of the literature published in MEDLINE-PubMed until the end of February 2021. After selection, 32 studies were included in the qualitative review comparing the miRNA expression profile in EVs between different pathological disorders. Most reports showed the potential of the miRNAs carried by EVs to be used as putative biomarkers of reproductive disorders, including pregnancy affections, disease progression and quality of preimplantation embryos. The most relevant miRNAs were found to be highly heterogeneous among studies, with some conflicting results. Further research is thus warranted to address whether cofounding factors, such as the methods to isolate EVs and miRNAs, the subset of EVs, the criteria of patient selection, the timing of sample retrieval, or any other factor, may explain the inconsistencies between studies.

Sperm DNA integrity does play a crucial role for embryo development after ICSI, notably when good-quality oocytes from young donors are used.

Based on the inconsistent literature published thus far involving infertile patients, whether intracytoplasmic sperm injection (ICSI) allows overcoming total fertilization failure due to sperm DNA fragmentation is still unclear. Related to this, female factors, which may have a significant impact on assisted reproduction outcomes, can mask male infertility. In this scenario, evaluating ICSI outcomes following cycles using healthy donor gametes could shed light on this realm, as it would avoid the influence of (un)known confounding factors present in infertile individuals. The present work, therefore, aimed to address whether single- and double-stranded sperm DNA fragmentation leads to impaired ICSI outcomes in double gamete donation cycles. The study also compared these double-gamete donation cycles to cycles in which only sperm were donated and oocytes were obtained from infertile patients. Two cohorts were included: (a) the Donor-Donor (DD) cohort, which included 27 semen donor samples used in 49 ICSI cycles with young healthy oocyte donors; and (b) the Donor-Infertile (DI) cohort, which involved 34 semen donor samples used in 57 ICSI cycles with oocytes from patients. Single- and double-stranded sperm DNA breaks were determined with alkaline and neutral Comet assays, respectively; ICSI was conducted following standard protocols and embryos were monitored through time-lapse microscopy. In the DD cohort, the percentage of sperm with high overall DNA damage correlated with fertilization rates (Rs = - 0.666; P < 0.001) and with the percentage of blastocysts per injected oocyte (Rs = - 0.414; P = 0.040). In addition, sperm DNA damage delayed the first embryo division (Rs = 0.421; P = 0.036), and development from the 8-cell to the morula stage (Rs = 0.424; P = 0.034). In contrast, double-stranded DNA breaks had no effect in this cohort. As far as the DI cohort is concerned, while overall sperm DNA damage was not found to be correlated to fertilization or blastocyst rates, pronuclei formation following ICSI was delayed when the incidence of double-stranded DNA breaks was high (Rs = 0.485; P = 0.005). In conclusion, this study, which is the first involving double donation cycles (i.e., a donor-donor cohort), supports that sperm DNA damage has a detrimental impact on fertilization rates after ICSI, and delays embryo development. Moreover, the use of oocytes from infertile individuals is suggested to hide the male-factor effect.

Cryoprotectant role of exopolysaccharide ID1 in the vitrification/in-straw warming of in vitro-produced bovine embryos.

The cold-adapted bacterium Pseudomonas sp. ID1 produces the extracellular exopolysaccharide ID1 (EPS ID1) with cryoprotective activity. This study was designed to optimize the vitrification/in-straw warming protocol of in vitro-produced (IVP) blastocysts by adding EPS ID1 to the vitrification media. Day 7-expanded blastocysts were vitrified/warmed using the VitTrans device after the addition of 0 or 100 µg/mL EPS ID1 to the vitrification media. Blastocysts vitrified by the Cryotop method and fresh non-vitrified blastocysts served as controls. Outcomes were assessed in the warmed embryos in terms of survival rates and mRNA relative abundances of BAX, BCL2, GPX1, and CDX2 genes. No differences in survival rates were observed at 3 h post-warming between vitrification treatments. At 24 h post-warming, the addition of EPS prior to vitrification with the VitTrans device produced similar survival rates to Cryotop-vitrified embryos and similar hatching rates to fresh non-vitrified or Cryotop-vitrified embryos. No differences emerged in BCL2 gene expression. Lower BAX (p < .05) and higher GPX1 (p < .05) and CDX2 (p < .1) gene expression were observed in expanded and/or hatched blastocysts derived from VitTrans-EPS-vitrified embryos when compared to those from the non-supplemented group. In conclusion, addition of EPS not only promoted blastocyst survival and hatching after VitTrans vitrification/warming but also modified the expression of genes associated with better embryo quality.

Disruption of human meiotic telomere complex genes TERB1, TERB2 and MAJIN in men with non-obstructive azoospermia.

Non-obstructive azoospermia (NOA), the lack of spermatozoa in semen due to impaired spermatogenesis affects nearly 1% of men. In about half of cases, an underlying cause for NOA cannot be identified. This study aimed to identify novel variants associated with idiopathic NOA. We identified a nonconsanguineous family in which multiple sons displayed the NOA phenotype. We performed whole-exome sequencing in three affected brothers with NOA, their two unaffected brothers and their father, and identified compound heterozygous frameshift variants (one novel and one extremely rare) in Telomere Repeat Binding Bouquet Formation Protein 2 (TERB2) that segregated perfectly with NOA. TERB2 interacts with TERB1 and Membrane Anchored Junction Protein (MAJIN) to form the tripartite meiotic telomere complex (MTC), which has been shown in mouse models to be necessary for the completion of meiosis and both male and female fertility. Given our novel findings of TERB2 variants in NOA men, along with the integral role of the three MTC proteins in spermatogenesis, we subsequently explored exome sequence data from 1495 NOA men to investigate the role of MTC gene variants in spermatogenic impairment. Remarkably, we identified two NOA patients with likely damaging rare homozygous stop and missense variants in TERB1 and one NOA patient with a rare homozygous missense variant in MAJIN. Available testis histology data from three of the NOA patients indicate germ cell maturation arrest, consistent with mouse phenotypes. These findings suggest that variants in MTC genes may be an important cause of NOA in both consanguineous and outbred populations.

Men's dietary patterns in relation to infertility treatment outcomes among couples undergoing in vitro fertilization.

PURPOSE(S): To evaluate the relationship of men's dietary patterns with outcomes of in vitro fertilization (IVF). METHODS: This is a prospective cohort study including 231 couples with 407 IVF cycles, presented at an academic fertility center from April 2007 to April 2018. We assessed diet with a validated food frequency questionnaire and identified Dietary Pattern 1 and Dietary Pattern 2 using principal component analysis. We evaluated adjusted probability of IVF outcomes across the quartiles of the adherence to two dietary patterns by generalized linear mixed models. RESULTS: Men had a median age of 36.8 years and BMI of 26.9 kg/m2. Women's median age and BMI were 35.0 years and 23.1 kg/m2, respectively. Adherence to Dietary Pattern 1 (rPearson=0.44) and Dietary Pattern 2 (rPearson=0.54) was positively correlated within couples. Adherence to Dietary Pattern 1 was positively associated with sperm concentration. A 1-unit increase in this pattern was associated with a 13.33 (0.71-25.96) million/mL higher sperm concentration. However, neither Dietary Pattern 1 nor Dietary Pattern 2 was associated with fertilization, implantation, clinical pregnancy, or live birth probabilities. CONCLUSIONS: Data-derived dietary patterns were associated with semen quality but unrelated to the probability of successful IVF outcomes.

Blocking NHE Channels Reduces the Ability of In Vitro Capacitated Mammalian Sperm to Respond to Progesterone Stimulus.

Few data exist about the presence and physiological role of Na+/H+ exchangers (NHEs) in the plasma membrane of mammalian sperm. In addition, the involvement of these channels in the ability of sperm to undergo capacitation and acrosomal reaction has not been investigated in any mammalian species. In the present study, we addressed whether these channels are implicated in these two sperm events using the pig as a model. We also confirmed the presence of NHE1 channels in the plasma membrane of ejaculated sperm by immunofluorescence and immunoblotting. The function of NHE channels during in vitro capacitation was analyzed by incubating sperm samples in capacitating medium for 300 min in the absence or presence of a specific blocker (DMA; 5-(N,N-dimethyl)-amiloride) at different concentrations (1, 5, and 10 µM); acrosome exocytosis was triggered by adding progesterone after 240 min of incubation. Sperm motility and kinematics, integrity of plasma and acrosome membranes, membrane lipid disorder, intracellular calcium and reactive oxygen species (ROS) levels, and mitochondrial membrane potential (MMP) were evaluated after 0, 60, 120, 180, 240, 250, 270, and 300 min of incubation. NHE1 localized in the connecting and terminal pieces of the flagellum and in the equatorial region of the sperm head and was found to have a molecular weight of 75 kDa. During the first 240 min of incubation, i.e., before the addition of progesterone, blocked and control samples did not differ significantly in any of the parameters analyzed. However, from 250 min of incubation, samples treated with DMA showed significant alterations in total motility and the amplitude of lateral head displacement (ALH), acrosomal integrity, membrane lipid disorder, and MMP. In conclusion, while NHE channels are not involved in the sperm ability to undergo capacitation, they could be essential for triggering acrosome exocytosis and hypermotility after progesterone stimulus.

The Role of the Epididymis and the Contribution of Epididymosomes to Mammalian Reproduction.

It is well-established that testicular spermatozoa are immature and acquire motility and fertilization capabilities during transit throughout the epididymis. The epididymis is a duct-like organ that connects the testis to the vas deferens and is comprised of four anatomical regions: the initial segment, caput, corpus, and cauda. Sperm maturation occurs during epididymal transit by the interaction of sperm cells with the unique luminal environment of each epididymal region. In this review we discuss the epididymis as an essential reproductive organ responsible for sperm concentration, maturation (including sperm motility acquisition and fertilizing ability), protection and storage. Importantly, we also discuss specific characteristics and roles of epididymal-derived exosomes (epididymosomes) in establishing sperm competency within the intricate process of reproduction. This review suggests that an increasing body of evidence is working to develop a complete picture of the role of the epididymis in male reproduction, offspring health, and disease susceptibility.

Lysine pathway metabolites and the risk of type 2 diabetes and cardiovascular disease in the PREDIMED study: results from two case-cohort studies.

BACKGROUND: The pandemic of cardiovascular disease (CVD) and type 2 diabetes (T2D) requires the identification of new predictor biomarkers. Biomarkers potentially modifiable with lifestyle changes deserve a special interest. Our aims were to analyze: (a) The associations of lysine, 2-aminoadipic acid (2-AAA) or pipecolic acid with the risk of T2D or CVD in the PREDIMED trial; (b) the effect of the dietary intervention on 1-year changes in these metabolites, and (c) whether the Mediterranean diet (MedDiet) interventions can modify the effects of these metabolites on CVD or T2D risk. METHODS: Two unstratified case-cohort studies nested within the PREDIMED trial were used. For CVD analyses, we selected 696 non-cases and 221 incident CVD cases; for T2D, we included 610 non-cases and 243 type 2 diabetes incident cases. Metabolites were quantified using liquid chromatography-tandem mass spectrometry, at baseline and after 1-year of intervention. RESULTS: In weighted Cox regression models, we found that baseline lysine (HR+1 SD increase = 1.26; 95% CI 1.06-1.51) and 2-AAA (HR+1 SD increase = 1.28; 95% CI 1.05-1.55) were both associated with a higher risk of T2D, but not with CVD. A significant interaction (p = 0.032) between baseline lysine and T2D on the risk of CVD was observed: subjects with prevalent T2D and high levels of lysine exhibited the highest risk of CVD. The intervention with MedDiet did not have a significant effect on 1-year changes of the metabolites. CONCLUSIONS: Our results provide an independent prospective replication of the association of 2-AAA with future risk of T2D. We show an association of lysine with subsequent CVD risk, which is apparently diabetes-dependent. No evidence of effects of MedDiet intervention on lysine, 2-AAA or pipecolic acid changes was found. Trial registration ISRCTN35739639; registration date: 05/10/2005; recruitment start date 01/10/2003.

Normalization matters: tracking the best strategy for sperm miRNA quantification.

STUDY QUESTION: What is the most reliable normalization strategy for sperm microRNA (miRNA) quantitative Reverse Transcription Polymerase Chain Reactions (qRT-PCR) using singleplex assays? SUMMARY ANSWER: The use of the average expression of hsa-miR-100-5p and hsa-miR-30a-5p as sperm miRNA qRT-PCR data normalizer is suggested as an optimal strategy. WHAT IS KNOWN ALREADY: Mean-centering methods are the most reliable normalization strategies for miRNA high-throughput expression analyses. Nevertheless, specific trustworthy reference controls must be established in singleplex sperm miRNA qRT-PCRs. STUDY DESIGN, SIZE DURATION: Cycle threshold (Ct) values from previously published sperm miRNA expression profiles were normalized using four approaches: (i) Mean-Centering Restricted (MCR) method (taken as the reference strategy); (ii) expression of the small nuclear RNA RNU6B; (iii) expression of four miRNAs selected by the Concordance Correlation Restricted (CCR) algorithm: hsa-miR-100-5p, hsa-miR-146b-5p, hsa-miR-92a-3p and hsa-miR-30a-5p; (iv) the combination of two of these miRNAs that achieved the highest proximity to MCR. PARTICIPANTS/MATERIALS, SETTING, METHODS: Expression profile data from 736 sperm miRNAs were taken from previously published studies performed in fertile donors (n = 10) and infertile patients (n = 38). For each tested normalizer molecule, expression ubiquity and uniformity across the different samples and populations were assessed as indispensable requirements for being considered as valid candidates. The reliability of the different normalizing strategies was compared to MCR based on the set of differentially expressed miRNAs (DE-miRNAs) detected between populations, the corresponding predicted targets and the associated enriched biological processes. MAIN RESULTS AND THE ROLE OF CHANCE: All tested normalizers were found to be ubiquitous and non-differentially expressed between populations. RNU6B was the least uniformly expressed candidate across samples. Data normalization through RNU6B led to dramatically misguided results when compared to MCR outputs, with a null prediction of target genes and enriched biological processes. Hsa-miR-146b-5p and hsa-miR-92a-3p were more uniformly expressed than RNU6B, but their results still showed scant proximity to the reference method. The highest resemblance to MCR was achieved by hsa-miR-100-5p and hsa-miR-30a-5p. Normalization against the combination of both miRNAs reached the best proximity rank regarding the detected DE-miRNAs (Area Under the Curve = 0.8). This combination also exhibited the best performance in terms of the target genes predicted (72.3% of True Positives) and their corresponding enriched biological processes (70.4% of True Positives). LARGE SCALE DATA: Not applicable. LIMITATIONS, REASONS FOR CAUTION: This study is focused on sperm miRNA qRT-PCR analysis. The use of the selected normalizers in other cell types or tissues would still require confirmation. WIDER IMPLICATIONS OF THE FINDINGS: The search for new fertility biomarkers based on sperm miRNA expression using high-throughput assays is one of the upcoming challenges in the field of reproductive genetics. In this context, validation of the results using singleplex assays would be mandatory. The normalizer strategy suggested in this study would provide a universal option in this area, allowing for normalization of the validated data without causing meaningful variations of the results. Instead, qRT-PCR data normalization by RNU6B should be discarded in sperm-miRNA expression studies. STUDY FUNDING/COMPETING INTERESTS: This work was supported by the 2014/SGR00524 project (Agència de Gestió d'Ajuts Universitaris i de Recerca, Generalitat de Catalunya, Spain) and UAB CF-180034 grant (Universitat Autònoma de Barcelona). Celia Corral-Vazquez is a recipient of a Personal Investigador en Formació grant UAB/PIF2015 (Universitat Autònoma de Barcelona). The authors report no conflict of interest.

Spermatozoa from infertile patients exhibit differences of DNA methylation associated with spermatogenesis-related processes: an array-based analysis.

The influence of aberrant sperm DNA methylation on the reproductive capacity of couples has been postulated as a cause of infertility. This study compared the DNA methylation of spermatozoa of 19 fertile donors and 42 infertile patients using the Illumina 450K array. Clustering analysis of methylation data arranged fertile and infertile patients into two groups. Bivariate clustering analysis identified a differential distribution of samples according to the characteristics of seminogram and age, suggesting a possible link between these parameters and specific methylation profiles. The study identified 696 differentially methylated cytosine-guanine dinucleotides (CpG) associated with 501 genes between fertile donors and infertile patients. Ontological enrichment analysis revealed 13 processes related to spermatogenesis. Data filtering identified a set of 17 differentially methylated genes, some of which had functions relating to spermatogenesis. A significant association was identified between RPS6KA2 hypermethylation and advanced age (P = 0.016); APCS hypermethylation and oligozoospermia (P = 0.041); JAM3/NCAPD3 hypermethylation and numerical chromosome sperm anomalies (P = 0.048); and ANK2 hypermethylation and lower pregnancy rate (P = 0.040). This description of a set of differentially methylated genes provides a framework for further investigation into the influence of such variation in male fertility in larger patient cohorts.

MicroRNAs and Drinking: Association between the Pre-miR-27a rs895819 Polymorphism and Alcohol Consumption in a Mediterranean Population.

Recently, microRNAs (miRNA) have been proposed as regulators in the different processes involved in alcohol intake, and differences have been found in the miRNA expression profile in alcoholics. However, no study has focused on analyzing polymorphisms in genes encoding miRNAs and daily alcohol consumption at the population level. Our aim was to investigate the association between a functional polymorphism in the pre-miR-27a (rs895819 A>G) gene and alcohol consumption in an elderly population. We undertook a cross-sectional study of PREvención con DIeta MEDiterránea (PREDIMED)-Valencia participants (n = 1007, including men and women aged 67 ± 7 years) and measured their alcohol consumption (total and alcoholic beverages) through a validated questionnaire. We found a strong association between the pre-miR-27a polymorphism and total alcohol intake, this being higher in GG subjects (5.2 ± 0.4 in AA, 5.9 ± 0.5 in AG and 9.1 ± 1.8 g/day in GG; padjusted = 0.019). We also found a statistically-significant association of the pre-miR-27a polymorphism with the risk of having a high alcohol intake (>2 drinks/day in men and >1 in women): 5.9% in AA versus 17.5% in GG; padjusted < 0.001. In the sensitivity analysis, this association was homogeneous for sex, obesity and Mediterranean diet adherence. In conclusion, we report for the first time a significant association between a miRNA polymorphism (rs895819) and daily alcohol consumption.

Is telomere length a biomarker of sperm quality? A systematic review and meta-analysis of observational studies.

BACKGROUND: Telomeres are essential for the integrity of chromosome ends during cell division and their involvement in different processes linked to aging has been established. These chromosome components are involved in spermatogenesis and seem to play an important role in fertilization and embryo development. Telomere length is shortened with each cell division. Recently, short sperm telomere length has been proposed as a potential biomarker of male infertility. OBJECTIVES: To conduct a systematic review and meta-analysis of studies exploring the association between spermatozoa and/or leukocyte telomere length with sperm quality parameters and different infertility conditions. MATERIAL AND METHODS: A systematic review and meta-analysis was conducted with studies from Medline-PUBMED and Cochrane Library databases until May 2022. Eligible studies included cohort, cross-sectional and case-control studies, and telomere length in spermatozoa and/or leukocytes cells was defined as the exposure. Semen quality parameters or infertility conditions (e.g., oligozoospermia, asthenozoospermia, teratozoospermia, or other spermatogenic impairment combinations) were defined as the outcomes. RESULTS: Twenty-three observational studies were included. In the qualitative analysis, high heterogeneity was observed between studies regarding the associations between telomere length and semen parameters in different normozoospermic/fertile and oligozoospermic/infertile populations. In the meta-analysis, spermatozoa and leukocyte telomere length were shorter in infertile individuals than in fertile individuals (mean difference [95% confidence interval]: -1.43 [-1.66 to -1.21], p-value <0.001 and -1.67 [-2.02 to -1.31], p-value <0.001, respectively). Moreover, in terms of sperm telomere length, these differences were also significant between individuals with a normal seminogram and individuals with a low quantity of spermatozoa in the ejaculate (-0.97 [-1.32, -0.61], p-value <0.001). CONCLUSION: The current systematic review and meta-analysis suggests the potential role of spermatozoa or leukocyte telomere length as a reliable biomarker of semen quality, which may help distinguish between infertility conditions beyond the routine semen analysis.

Blastocoel fluid aspiration improves vitrification outcomes and produces similar sexing results of in vitro-produced cattle embryos compared to microblade biopsy.

The potential applications of in vitro-produced (IVP) cattle embryos are significantly enhanced when combined with genotype selection and cryopreservation techniques. While trophectoderm (TE) biopsies are frequently used for genotyping, cell-free DNA (cfDNA) found in blastocoele fluid (BF) arises as a less-invasive method. Moreover, the blastocoel collapse produced by BF aspiration could be beneficial for embryo cryotolerance. This study was conducted to test the BF as a source of cell free-DNA (cfDNA) and to compare the BF to the TE biopsy in terms of sexing efficiency/accuracy, embryo survival and gene expression after vitrification/warming. IVP day 7 expanded blastocysts were artificially collapsed by aspiration of BF (VIT-Collapsed) or biopsied (VIT-Biopsied). After sample collection, embryos were vitrified/warmed by the Cryotop method and individually cultured in vitro. Intact fresh non-vitrified and vitrified/warmed blastocysts served as Fresh Control and VIT-Control, respectively. After sex identification of BF or TE biopsies and the corresponding surviving embryos, amplification efficiency and sexing accuracy were assessed. There were no differences between the BF and TE biopsy samples in terms of sexing accuracy or efficiency. Although all vitrified groups showed lower post-warming re-expansion rates (p < 0.05), the blastocyst re-expansion rates in the VIT-Collapsed group were comparable to those in the Fresh Control group whereas biopsied blastocysts showed the lowest (p < 0.05) re-expansion rates. VIT-Collapsed blastocysts had hatching rates that were comparable to those of Fresh Control blastocysts but significantly higher than those of the other vitrification treatments. Proapoptotic gene BAX was overexpressed in VIT-Biopsied embryos, whereas BCL2 transcripts were more abundant in the VIT-Collapsed group. On the other hand, VIT-Biopsied embryos showed altered ATP1B1- and AQP3-mRNA levels. The analysis of the cfDNA present in the BF is an efficient, minimally invasive approach to sex IVP cattle embryos. Besides, the artificial collapse of blastocoel prior to vitrification resulted in higher re-expansion and hatching ability than when embryos were vitrified after being biopsied.

Ultra-processed food consumption and semen quality parameters in the Led-Fertyl study.

STUDY QUESTION: Is ultra-processed food (UPF) consumption associated with semen quality parameters? SUMMARY ANSWER: Higher UPF consumption was inversely associated with total sperm count, sperm concentration, and total motility in men of reproductive age. WHAT IS KNOWN ALREADY: The consumption of UPF, which has been rising during the last decades, has been demonstrated to be positively associated with several chronic diseases such as diabetes or cardiovascular diseases. However, the scientific evidence on its potential impact on semen quality remains notably limited. STUDY DESIGN SIZE DURATION: A cross-sectional analysis was conducted using data from 200 healthy men (mean age 28.4 ± 5.5 years) enrolled in the Led-Fertyl (Lifestyle and Environmental Determinants of Seminogram and Other Male Fertility-Related Parameters) study between February 2021 and April 2023. PARTICIPANTS/MATERIALS SETTING METHODS: UPF consumption (% of energy from UPF) was estimated according to the NOVA classification system using a validated 143-item semi-quantitative food frequency questionnaire. Total sperm count, sperm concentration, sperm vitality, total motility, progressive motility, and normal sperm forms were set as the main outcomes. Microscopic parameters were analyzed using a phase-contrast microscope and a computer-assisted sperm analysis (CASA) system. Semen samples were collected and tested according to World Health Organization 2010 standards. Multivariable linear regression models were fitted to estimate the associations between UPF tertile and semen quality parameters. MAIN RESULTS AND THE ROLE OF CHANCE: Sperm concentration (ß: -1.42 × 106 spz./ml; 95% CI: -2.72 to -0.12) and motility (ß: -7.83%; 95% CI: -15.16 to -0.51) were lower in participants in the highest tertile of UPF compared to the lowest. A similar association was observed for sperm count when UPF was analyzed per 10% increment of energy from UPF consumption (ß: -1.50 × 106 spz.; 95% CI: -2.83 to -0.17). Theoretically replacing 10% of energy from UPF consumption with 10% of energy from unprocessed or minimally processed food consumption was associated with a higher total sperm count, sperm concentration, total motility, progressive motility, and normal sperm forms. LIMITATIONS REASONS FOR CAUTION: Cross-sectional studies do not permit the drawing of causal inferences. Measurement errors and reporting bias cannot be entirely ruled out. WIDER IMPLICATIONS OF THE FINDINGS: This work suggests that consumption of UPF may have an impact on certain semen quality parameters. Furthermore, opting for unprocessed or minimally processed foods instead of UPFs could potentially benefit semen quality. If these results are replicated in future epidemiological studies with different long-term designs, these novel findings could provide valuable insights for updating or even designing preventive and interventional programs to address infertility among men of reproductive age. STUDY FUNDING/COMPETING INTERESTS: This study was supported by the Spanish government's official funding agency for biomedical research, ISCIII, through the Fondo de Investigación para la Salud (FIS), the European Union ERDF/ESF, 'A way to make Europe'/'Investing in your future' [PI21/01447], and the Diputació de Tarragona (2021/11-No.Exp. 8004330008-2021-0022642). J.S.-S. gratefully acknowledges the financial support of ICREA under the ICREA Academia program. C.V.-H. received a predoctoral grant from the Generalitat de Catalunya (2022 FI_B100108). M.Á.M. was supported by the Sara Borrell postdoctoral fellowship (CD21/00045-Instituto de Salud Carlos III (ISCIII)). M.F.d.l.P. was supported by a predoctoral grant from the Rovira i Virgili University and Diputació de Tarragona (2020-PMF-PIPF-8). All authors have no conflict of interest to declare. TRIAL REGISTRATION NUMBER: N/A.

Sperm Quality and Fertility of Livestock Animals.

Recent research has focused on the understanding of the causes of subfertility observed in livestock species, evidencing that different factors could underlie this condition [...].