Elucidating the impact of Y chromosome microdeletions and altered gene expression on male fertility in assisted reproduction.

BACKGROUND: Genetic abnormalities like Y chromosome microdeletions are implicated in male infertility. This study investigated the association of azoospermia factor (AZF) region microdeletions with unsuccessful assisted reproductive techniques (ART), including in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI). METHODS: This cross-sectional analysis study examined 80 Iranian oligospermic men (mean age 34 years) with prior failed ICSI and IVF cycles (IR.IAU.TNB.REC.1401.041). Semen analysis evaluated quantity/quality parameters based on World Health Organization guidelines. Participants were stratified by sperm DNA fragmentation (SDF) levels into: control (SDF < 15%, n = 20), mild elevation (15% ≤ SDF ≤ 30%, n = 60), and high (SDF > 30%, n = 20). Multiplex PCR mapped AZF microdeletions in the high SDF group. The AZF-associated genes were selected by RNA Seq analysis, and the candidate genes were checked for expression level by real-time PCR. RESULTS: High SDF individuals exhibited poorer semen metrics, including 69% lower sperm concentration (P = 0.04) than those without SDF. Of this subset, 45% (9/20 men) harboured predominately AZF microdeletions. Men with AZF microdeletions showed higher SDF (32% vs 21%, P = 0.02) and altered AZF-associated genes expression. As USP9Y 3-fold, UTY 1.3-fold, and BPY2 1-fold revealed up-regulation, while IQCF1 8-fold, CDY 6.5-fold, DAZ 6-fold, and DDX3Y 1-fold underwent down-regulation. The PAWP gene was also down-regulated (5.7-fold, P = 0.029) in the IVF/ICSI failure group. CONCLUSION: AZF microdeletions significantly impact male infertility and ART outcomes. High SDF individuals exhibited poorer semen metrics, with 45% AZF microdeletions. These microdeletions altered AZF-associated genes expression, affecting fertility mediator PAWP independently. Dual AZF and SDF screening enables personalized management in severe male infertility, potentially explaining IVF/ICSI failures.

One out of two idiopathic infertile men has pathologic sperm DNA fragmentation values: Potential implications for clinical practice.

OBJECTIVES: To investigate the distribution of sperm DNA fragmentation (SDF) values and their association with clinical and seminal parameters in idiopathic infertile men. DESIGN, PATIENTS, MEASUREMENTS: Data from 3224 primary infertile men (belonging to couples having failed to conceive a pregnancy within 12 months) who underwent a thorough diagnostic work-up were analysed. A SDF value ≥ 30% (according to Sperm Chromatin Structure Assay) was considered pathologic. We excluded: (1) men with genetic abnormalities; (2) men with history of cryptorchidism; (3) men with biochemical hypogonadism; (4) men with clinical varicocele; and (5) men with other possible known aetiological factors. Descriptive statistics and logistic regression analyses were used to describe the whole cohort. RESULTS: Of all, 792 (23%) men with at least one abnormal WHO semen parameter but without any identified aetiologic factor for infertility, were considered as idiopathic infertile men. Of 792, 418 (52.7%) men had SDF ≥30%. Men with pathologic SDF were older (p = .02), had higher Follicle-stimulating hormone (FSH) (p = .04) but lower total testosterone (p = .03) values than those with SDF <30%. The homoeostatic model assessment index for insulin resistance (HOMA-IR) was higher in men with SDF ≥30% (p = .01). Idiopathic infertile men with SDF ≥30% presented with lower sperm concentration (p < .001) and lower progressive sperm motility (p < .01) than those with SDF < 30%. Logistic regression analysis revealed that older age (OR: 1.1, p = .02) and higher HOMA-IR score (OR: 1.8, p = .03) were associated with SDF ≥ 30%, after accounting for FSH and sperm concentration values. CONCLUSIONS: Approximately half of infertile men categorized as idiopathic had pathologic SDF values. Idiopathic infertile men with pathologic SDF showed worse clinical, hormonal and semen parameters than those with normal SDF values. These results suggest that including SDF testing could be clinically relevant over the real-life management work-up of infertile men.

Severe sperm DNA fragmentation may persist for up to 3 years after cytotoxic therapy in patients affected by Hodgkin lymphoma and non-Hodgkin lymphoma.

STUDY QUESTION: Does sperm DNA recover from damage in all men after 2 years from the end of cytotoxic treatments? SUMMARY ANSWER: The current indication of 2 years waiting time for seeking natural pregnancy after cytotoxic treatment may not be adequate for all men, since severe sperm DNA damage is present in a proportion of subjects even after this timeframe. WHAT IS KNOWN ALREADY: Data in the literature on sperm DNA fragmentation (SDF) in lymphoma patients after cytotoxic treatments are scarce. The largest longitudinal study evaluated paired pre- and post-therapy (up to 24 months) semen samples from 34 patients while one study performed a longer follow-up (36 months) in 10 patients. The median/mean SDF values >24 months after therapy did not show significant differences but the studies did not explore the proportion of patients with severe DNA damage and the analysis was done on frozen-thawed samples. STUDY DESIGN, SIZE, DURATION: In this study, 53 Hodgkin lymphoma (HL) and 25 non-Hodgkin lymphoma (NHL) post-pubertal patients were included over a recruitment period of 10 years (2012-2022). Among them, 18 subjects provided paired semen samples for SDF analysis at the three time points. SDF was evaluated in patients before (T0) and after 2 (T2) and 3 years (T3) from the end of, cytotoxic treatments (chemotherapy alone or in combination with radiotherapy). A cohort of 79 healthy, fertile, and normozoospermic men >18 years old served as controls (recruited between 2016 and 2019). PARTICIPANTS/MATERIALS, SETTING, METHODS: SDF was evaluated on fresh semen samples (i.e. spermatozoa potentially involved in natural conception) from patients and controls using TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling) assay coupled with flow cytometry. SDF median values were compared between groups: (i) HL and NHL patients versus controls at the three time points; (ii) HL versus NHL patients at baseline; and (iii) patients at T0 versus T2 and T3. Severe DNA damage (SDD) was defined for SDF levels above the 95th percentile of controls (50%) and the proportion of patients with SDD at all time points was established. MAIN RESULTS AND THE ROLE OF CHANCE: At T0, patients displayed higher median SDF than controls, reaching statistical significance in the NHL group: 40.5% [IQR: 31.3-52.6%] versus 28% [IQR: 22-38%], P < 0.05. Comparing SDF pre-treatment to that post-treatment, HL patients exhibited similar median values at the three time points, whereas NHL showed significantly lower values at T3 compared to T0: 29.2% [IQR: 22-38%] versus 40.5% [IQR: 31.3-52.6%], P < 0.05. The proportion with SDD in the entire cohort at T2 was 11.6% and 13.3% among HL and NHL patients, respectively. At T3, only one in 16 NHL patients presented SDD. LIMITATIONS, REASONS FOR CAUTION: TUNEL assay requires at least 5 million spermatozoa to be performed; hence, severe oligozoospermic men were not included in the study. Although our cohort represents the largest one in the literature, the relatively small number of patients does not allow us to establish precisely the frequency of SDD at T2 which in our study reached 11-13% of patients. WIDER IMPLICATIONS OF THE FINDINGS: Our data provide further insights into the long-term effects of cytotoxic treatments on the sperm genome. The persistent severe DNA damage after 2 years post-treatment observed in some patients suggests that there is an interindividual variation in restoring DNA integrity. We propose the use of SDF as a biomarker to monitor the treatment-induced genotoxic effects on sperm DNA in order to better personalize pre-conceptional counseling on whether to use fresh or cryopreserved spermatozoa. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by grants from the Istituto Toscano Tumori (ITT), Fondazione Ente Cassa di Risparmio di Firenze, the European Commission-Reproductive Biology Early Research Training (REPROTRAIN). C.K., G.F., V.R., and A.R.-E. belong to COST Action CA20119 (ANDRONET) which is supported by the European Cooperation in Science and Technology (www.cost.eu). The authors declare no conflict of interest. TRIAL REGISTRATION NUMBER: N/A.

Prospective reproductive outcomes according to sperm parameters, including DNA fragmentation, in recurrent pregnancy loss.

RESEARCH QUESTION: Are the prospective reproductive outcomes in couples experiencing recurrent pregnancy loss (RPL) related to the sperm DNA fragmentation index (DFI), as measured by sperm chromatin structure assay, sperm morphology and sperm concentration at referral? DESIGN: This prospective cohort study included 95 couples seen between 1 April 2018 and 1 December 2019 at the tertiary Copenhagen RPL Unit, Copenhagen University Hospital, Rigshospitalet and Hvidovre Hospital, Denmark. The couples had experienced three or more unexplained consecutive pregnancy losses or two late pregnancy losses (>12 weeks gestation). Follow-up was 12-31 months. RESULTS: Eighty-one of 95 (85.3%) couples achieved pregnancy after referral. In the first pregnancy after referral, 46 (56.8%) couples achieved a live birth, and 35 (43.2%) couples experienced another pregnancy loss. There was no significant difference in baseline DFI between couples that experienced pregnancy loss [median 11.7, interquartile range (IQR) 9.1-17.3] and couples that achieved a live birth (median 12.5, IQR 9.3-16.5; P = 0.971). Improving sperm morphology increased the odds of a live birth after referral (adjusted OR 1.26, 95% CI 1.05-1.52; P = 0.014). DFI and sperm concentration were not associated with the outcome of the first pregnancy after referral. Overall, 35.9% of the men had DFI ≥15 at inclusion. Couples that failed to achieve pregnancy had a higher median DFI of 17.7 (IQR 7.7-27.2) compared with the rest of the cohort (median 12.0, IQR 9.3-16.5; P = 0.041). CONCLUSIONS: At referral, sperm DFI, morphology and concentration cannot be used to identify RPL couples at risk of another pregnancy loss. Increased baseline DFI was associated with difficulty achieving another pregnancy, and improving sperm morphology was associated with increased odds of a live birth.

Quantifying the association of sperm DNA fragmentation with assisted reproductive technology outcomes: An umbrella review.

BACKGROUND: Systematic reviews and meta-analyses are instrumental in shaping clinical practice. However, their findings can sometimes be marred by discrepancies and potential biases, thereby diluting the strength of the evidence presented. Umbrella reviews serve to comprehensively assess and synthesise these reviews, offering a clearer insight into the quality of the evidence presented. In the context of the relationship between sperm DNA fragmentation (SDF) and assisted conception outcomes, there is a divergence in the literature. Some reviews suggest a clear cause-and-effect linkage, whereas others present conflicting or inconclusive results. OBJECTIVES: In this umbrella review we aimed to synthesise the evidence collated in systematic reviews and meta-analyses summarising the association of SDF with assisted reproductive technology (ART) outcomes. SEARCH STRATEGY: After preregistration (https://doi.org/10.17605/OSF.IO/6JHDP), we performed a comprehensive search of the PubMed, Scopus, Cochrane Library, Web of Science and Embase databases. We conducted a search for systematic reviews on the association between SDF and ART without any restrictions on language or publication date. SELECTION CRITERIA: Systematic reviews and meta-analyses assessing the association between SDF and ART outcomes were eligible. DATA COLLECTION AND ANALYSIS: We assessed the quality of the included reviews using AMSTAR 2 and ROBIS, and determined the degree of overlap of primary studies between reviews estimating the corrected covered area (CCA), adjusted for structural missingness. We evaluated the most recent reviews assessing the association of SDF with live birth, pregnancy, miscarriage, implantation, blastulation and fertilisation. The synthesis of evidence was harmonised across all included quantitative syntheses, re-estimating the odds ratio (eOR) in random-effects meta-analyses with 95% confidence intervals (95% CIs) and 95% prediction intervals (95% PIs). We categorised the evidence strength into convincing, highly suggestive, suggestive, weak or nonsignificant, according to the meta-analysis re-estimated P-value, total sample size, I2 statistic for heterogeneity, small study effect, excess significance bias and the largest study significance. MAIN RESULTS: We initially captured and screened 49 332 records. After excluding duplicate and ineligible articles, 22 systematic reviews, 15 of which were meta-analyses, were selected. The 22 reviews showed a moderate degree of overlap (adjusted CCA 9.2%) in their included studies (overall n = 428, with 180 unique studies). The 15 meta-analyses exhibited a high degree of overlap (adjusted CCA = 13.6%) in their included studies (overall n = 274, with 118 unique studies). AMSTAR 2 categorised the quality of evidence in 18 reviews as critically low and the quality of evidence in four reviews as low. ROBIS categorised all the reviews as having a high risk of bias. The re-estimated results showed that the association of SDF with live birth was weak in one and nonsignificant in four meta-analyses. Similarly, the association of SDF with pregnancy, miscarriage, implantation, blastulation and fertilisation was also weak or nonsignificant. The association of high SDF with different ART outcomes was also weak or nonsignificant for different interventions (IVF, ICSI and IUI) and tests. CONCLUSIONS: This umbrella review did not find convincing or suggestive evidence linking SDF with ART outcomes. Caution should be exercised in making any claims, policies or recommendations concerning SDF.

Investigation of sperm hsa-mir-145-5p and MLH1 expressions, seminal oxidative stress and sperm DNA fragmentation in varicocele.

BACKGROUND: Mechanisms by which varicocele causes infertility are not clear and few studies have reported that some miRNAs show expression alterations in men with varicocele. Recently, sperm promoter methylation of MLH1 has been shown to be higher in men diagnosed with varicocele. This study aimed to assess the potential effects of miR-145, which was determined to target MLH1 mRNA in silico on sperm quality and function in varicocele. METHODS: Sperm miR-145 and MLH1 expressions of six infertile men with varicocele (Group 1), nine idiopathic infertile men (Group 2), and nine fertile men (control group) were analyzed by quantitative PCR. Sperm DNA fragmentation was evaluated by TUNEL and the levels of seminal oxidative damage and total antioxidant capacity were analyzed by ELISA. RESULTS: Our results have shown that sperm expression of miR-145 was decreased in Group 1 compared to Group 2 (P = 0.029). MLH1 expression was significantly higher in Group 2 than the controls (P = 0.048). Total antioxidant level and sperm DNA fragmentations of Group 1 and Group 2 were decreased (P = 0.001 and P = 0.011, respectively). Total antioxidant capacity was positively correlated with sperm concentration (ρ = 0.475, P = 0.019), total sperm count (ρ = 0.427, P = 0.037), motility (ρ = 0.716, P < 0.0001) and normal morphological forms (ρ = 0.613, P = 0.001) and negatively correlated with the seminal oxidative damage (ρ=-0.829, P = 0.042) in varicocele patients. CONCLUSION: This is the first study investigating the expressions of sperm miR-145 and MLH1 in varicocele patients. Further studies are needed to clarify the potential effect of miR-145 on male fertility.

Antioxidant Genes Variants and Their Association with Sperm DNA Fragmentation.

Semen possesses a variety of antioxidant defense mechanisms which protect sperm DNA from the damaging effects of oxidative stress. Correlation between antioxidant genes variants and sperm DNA fragmentation (SDF) level is not sufficiently studied. Therefore, we investigated the association between several single nucleotide polymorphisms (SNPs): CYP1A1 (rs1048943A > G), CYP4F2 (rs2108622G > A), NRF2 (rs6721961C > A), PON1 (rs662A > G), NOS3 (rs1799983G > T), GSTM1 (null), CAT (rs1001179C > T), SOD2 (rs4880A > G), GSTP1 (rs1695A > G), PON2 (rs7493G > C), EPHX2 (rs1042064T > C), and AHR (rs2066853G > A) and elevated SDF. The study employed a case-control design where, the allele and genotype frequencies of the selected SNPs were compared between 75 semen samples with abnormal SDF (the cases) and 75 samples with normal SDF (the controls). DNA was extracted from the semen samples and allele-specific PCR (AS-PCR) was used for genotyping the SNPs. Relevant data were collected from the patients' records et al.-Basma Fertility Center. Suitable statistical tests and multifactorial dimensionality reduction (MDR) test were used to anticipate SNP-SNP interactions. Comparison of semen parameters revealed significant differences between cases and controls in terms of liquefaction time, sperm total motility, and normal form. Genotype frequencies of NOS3 G > T (GT), SOD2 A > G (AA and AG), EPHX2 T > C (CC and CT), and AHR G > A (GA and GG) were significantly different between cases and controls. Allele frequencies of SOD2 (G-allele), and EPHX2 (T-allele) also significantly varied between cases and controls. MDR analysis revealed that the NOS3, SOD2, and EPHX2 SNPs combination has the highest impact on SDF. The study findings suggest that genetic variations in genes involved antioxidant defenses contribute to abnormal SDF.

Epigenetic transgenerational effects of PM2.5 collected from southern Taiwan on sperm functions and DNA methylation in mouse offspring.

During respiration, particulate matter with a diameter of 2.5 µm or less (PM2.5) suspended in the atmosphere enters the terminal alveoli and blood. PM2.5 particles can attach to toxic substances, resulting in health problems. Limited information is available regarding the effects of prenatal exposure to water-soluble PM2.5 (WS-PM2.5) and water-insoluble PM2.5 (WI-PM2.5) on male reproduction. In addition, whether exposure to these particles has transgenerational effects remains unknown. We investigated whether prenatal exposure to WS-PM2.5 and WI-PM2.5 disrupts sperm function in generations F1, F2, and F3 of male mice. Pregnant BALB/c mice were treated using intratracheal instillation on gestation days 7, 11, and 15 with 10 mg of a water extract or insoluble PM2.5. On postnatal day 105, epididymal sperm count, motility, morphology, mitochondrial membrane potential (MMP), reactive oxygen species (ROS) production, the sperm chromatin DNA fragmentation index (DFI), and testicular DNA methyltransferase (Dnmt) levels were evaluated in all generations. Whole-genome bisulfite sequencing was used to analyze the DNA methylation status of generation F3. According to the results, exposure to WS-PM2.5 affected sperm morphology, ROS production, and mean DFI in generation F1; ROS production and mean DFI in generation F2; and sperm morphology and MMP in generation F3. Similarly, exposure to WI-PM2.5 affected sperm morphology, ROS production, mean DFI, %DFI, and Dnmt1 expression in generation F1; sperm morphology, MMP, and ROS production in generation F2; and sperm morphology, ROS, and %DFI in generation F3. Two hypermethylated genes, PRR16 and TJP2, were observed in the WS-PM2.5 and WI-PM2.5 groups, two hypomethylated genes, NFATC1 and APOA5, were observed in the WS-PM2.5 group, and two hypomethylated genes, ZFP945 and GSE1, were observed in the WI-PM2.5 group. Hence, prenatal exposure to PM2.5 resulted in transgenerational epigenetic effects, which may explain certain phenotypic changes in male reproduction.

Association between semen parameters and recurrent pregnancy loss: An umbrella review of meta-analyses.

AIM: Recurrent pregnancy loss (RPL) is a common clinical reproductive problem. With research advancements, an increasing number of studies have suggested that male factors play an important role in RPL. However, the evaluation results of male sperm quality in published meta-analyses are inconsistent. We aimed to summarize the evidence of the association between semen factors and RPL and evaluate the level and validity of the evidence. METHODS: We searched PubMed, Cochrane Library, EMBASE, Web of Science, and Scopus databases for systematic reviews or meta-analyses to evaluate the association between male semen parameters and RPL. The methodological quality of the included meta-analyses was assessed, and data and evidence were re-synthesized and stratified using a random-effects model. RESULTS: Seven meta-analyses and nine semen parameters were included in the final analysis. The methodological quality of all publications was considered low or very low. There was highly suggestive evidence for the association between sperm DNA fragmentation (SDF), sperm progressive motility rate, and RPL (class II). The evidence level for the association between sperm concentration, normal sperm morphology, sperm deformity rate, total motility, and RPL was suggestive evidence (class III). The evidence level for the association between sperm volume and sperm count and RPL was weak (class IV). There was no significant association between sperm pH and RPL (class NS). CONCLUSIONS: Our results suggest level II evidence for the association between male SDF and RPL, while the evidence level for the association between conventional semen routine parameters and RPL was low (classes III and IV).

Impact of sperm DNA fragmentation in couples with unexplained recurrent pregnancy loss: A cross-sectional study.

OBJECTIVE: Recurrent pregnancy loss (RPL) has a multifactorial etiology, with a majority of cases remaining unexplained. To account for these unexplained cases, possible male factors are being explored. Conventional semen analysis lacks a qualitative assessment of sperms and information regarding sperm DNA integrity. Sperm DNA fragmentation (SDF) has diagnostic value in unexplained RPL, and it may account for a number of unexplained cases. Hence, we planned a study to explore and evaluate the impact of sperm DNA fragmentation in couples with unexplained recurrent pregnancy losses. STUDY DESIGN: Analytical cross-sectional study was conducted at a tertiary-level referral facility in India between August 2021 and July 2023. Participants (n = 70) were divided into two groups-male partners of couples with unexplained RPL (following spontaneous conceptions) (n = 35) and men with at least one previous live birth (spontaneous or following fertility treatments for female factor infertility such as ovulation induction or intrauterine insemination) as controls (n = 35). Neither of the two groups of couples recruited for this study had undergone ART as fertility treatment. Primary outcome assessed was mean DNA fragmentation index (DFI). Secondary outcomes included differences in semen parameters such as sperm concentration, progressive sperm motility and morphology, proportion of men with high (≥30%) and low DFI in the two groups, and the association between various semen parameters and DFI. RESULTS: Univariate logistic regression revealed that sperm DNA fragmentation was higher in men with unexplained RPL (30.0; IQR (interquartile range) 19.0, 46.0) as compared to controls (22.0; IQR 14.0, 30.0) although it was not statistically significant (OR, odds ratio, 1.02; 95% CI 1.0-1.1, p = 0.08). A higher proportion of men with unexplained RPL had DFI ≥30% compared to controls (54.2% vs. 25.7%; OR 3.43 (95% CI 1.2-9.4); p = 0.02). No statistically significant differences were observed in semen volume, sperm concentration, progressive motility, and morphology between the two groups. Sperm DNA fragmentation index also showed a weak but significant inverse relationship with sperm morphology (r = -0.336, p = 0.004). CONCLUSION: The current study did not show any significant difference in the mean sperm DNA fragmentation levels in male partners of couples with unexplained RPL compared to controls. However, a higher proportion of men with DFI ≥30% were observed in unexplained RPL population when compared to controls.

In cases with raised sperm DNA fragmentation, can sperm selection by magnetic-activated cell sorting or testicular sperm aspiration help improve reproductive outcomes?

PURPOSE: To evaluate the efficacy of magnetic-activated cell sorting (MACS) or testicular sperm aspiration (TESA) to improve reproductive outcomes in cases with elevated sperm DNA fragmentation undergoing assisted reproduction. METHODS: This randomized controlled trial included couples with failed IVF cycles and sperm DNA fragmentation > 30%. Sperm DNA fragmentation was assessed using the sperm chromatin structure assay (SCSA) method. Participants were randomly assigned to either the MACS or TESA group. Testicular sperm retrieval was performed for the TESA group, while MACS involved sperm selection using magnetic beads. Extended blastocyst culture, freeze all policy of blastocysts by vitrification, and frozen embryo transfer were undertaken as per clinic's standard operating protocols. Blastocyst formation rate, implantation rate, miscarriage rate, multiple pregnancy rate, and live birth rate were analyzed and compared between MACS and TESA groups. RESULTS: There were no significant differences in female age, male age, or sperm DNA fragmentation index (DFI) between the MACS and TESA groups. The blastocyst conversion rate was slightly higher in the TESA group (39%) compared to the MACS group (32%). However, the MACS group had a higher implantation rate (50%) than the TESA group (35%). Miscarriage rates, multiple pregnancy rates, and live birth rates did not show statistically significant differences between the groups. A chi-squared test was conducted to compare categorical variables, and t-tests were done to compare continuous variables. CONCLUSION: In cases with raised sperm DNA fragmentation, sperm selection by MACS or TESA seems to offer comparable reproductive outcomes. There seems no superiority of one intervention over the other in cases with raised sperm DNA fragmentation undergoing assisted reproduction. Both interventions seem to be beneficial for couples seeking assisted reproduction with raised sperm DNA fragmentation.

Sperm Chromatin Dispersion Test Detects Sperm DNA Fragmentation Mainly Associated with Unviable Spermatozoa and Underestimates the Values with Respect to TUNEL Assay.

Several clinical laboratories assess sperm DNA fragmentation (sDF) in addition to semen analysis in male infertility diagnosis. Among tests evaluating sDF, TUNEL (Terminal deoxynucleotidyl transferase dUTP nick end labeling) and SCD (Sperm Chromatin Dispersion) are widely used. Our lab developed a modified version of TUNEL (TUNEL/PI) able to distinguish two sperm populations (PI Brighter and PI Dimmer) differently associated with sperm viability and reproductive outcomes. The aim of this study was to compare sDF levels detected by SCD and TUNEL/PI in the semen samples from 71 male subjects attending our Andrology Laboratory. Our results demonstrate that SCD is less sensitive in determining sDF compared to TUNEL/PI. The statistically significant positive correlation found between sDF evaluated by SCD and PI Dimmer (consisting of all dead spermatozoa) suggests that SCD mainly detects sDF in unviable spermatozoa. We confirmed that most spermatozoa detected by SCD are unviable by performing SCD after incubation in hypo-osmotic medium to discriminate viable and unviable cells in 52 samples. Such results might explain the lower ability of this test in discriminating couples having successful ART outcomes demonstrated in published metanalyses. Overall, our results indicate that SCD is less sensitive in evaluating sDF for diagnostic purposes.

H2BFWT Variations in Sperm DNA and Its Correlation to Pregnancy.

Abnormalities in sperm nuclei and chromatin can interfere with normal fertilization, embryonic development, implantation, and pregnancy. We aimed to study the impact of H2BFWT gene variants in sperm DNA on ICSI outcomes in couples undergoing ART treatment. One hundred and nineteen partners were divided into pregnant (G1) and non-pregnant (G2) groups. After semen analysis, complete DNA was extracted from purified sperm samples. The sequence of the H2BFWT gene was amplified by PCR and then subjected to Sanger sequencing. The results showed that there are three mutations in this gene: rs7885967, rs553509, and rs578953. Significant differences were shown in the distribution of alternative and reference alleles between G1 and G2 (p = 0.0004 and p = 0.0020, respectively) for rs553509 and rs578953. However, there was no association between these SNPs and the studied parameters. This study is the first to shed light on the connection between H2BFWT gene variants in sperm DNA and pregnancy after ICSI therapy. This is a pilot study, so further investigations about these gene variants at the transcriptional and translational levels will help to determine its functional consequences and to clarify the mechanism of how pregnancy can be affected by sperm DNA.

Age, sexual abstinence duration, sperm morphology, and motility are predictors of sperm DNA fragmentation.

Purpose: Sperm DNA fragmentation (SDF) has recently received attention as a cause of male infertility. However, SDF cannot be fully assessed using conventional semen parameter evaluations alone. Therefore, the authors aimed to elucidate the relationship between SDF and sperm parameters via computer-assisted sperm analysis (CASA) to improve treatment strategies in reproductive medicine. Methods: This retrospective observational study analyzed the relationship between sperm parameters assessed by CASA and SDF values determined by the TUNEL assay in 359 patients who visited the Mie University Hospital for infertility treatment. The methodology involved semen analyses covering concentration, motility, and morphology, followed by SDF quantification using the flow cytometry. Results: Statistical analysis revealed significant correlations between SDF and various factors, including age, sexual abstinence period, and specific CASA-measured parameters. Notably, lower sperm motility rates and abnormal head dimensions were associated with higher SDF values, indicating that these parameters were predictive of SDF. Conclusions: This study highlights the importance of sperm motility and head morphology as indicators of SDF, suggesting their usefulness in assessing male fertility. These findings demonstrate the efficacy of detailed sperm analysis, potentially increasing the success rate of assisted reproductive technologies by improving sperm selection criteria.

Swim-up method is superior to density gradient centrifugation for preserving sperm DNA integrity during sperm processing.

Purpose: This study aimed to evaluate the effects of swim-up and density gradient centrifugation methods on sperm DNA fragmentation. Methods: Nineteen normozoospermic patient samples with ≥100 × 106 motile sperms were included in this study. Sperm DNA fragmentation, progressive motility, and progressive motile sperm number were measured before and after the swim-up method or density gradient centrifugation. Results: Sperm DNA fragmentation was not statistically different between swim-up-(14.4 ± 2.1%, p = 0.32) and density gradient centrifugation-processed (25.0 ± 3.0%, p = 0.20) and unprocessed semen samples (19.2 ± 1.9%). Sperm DNA fragmentation was significantly lower in swim-up-than in density gradient centrifugation-processed samples (p < 0.05). Sperm progressive motility was significantly higher (p < 0.05) in swim-up-(92.9 ± 1.0%) and density gradient centrifugation-processed (81.3 ± 2.0%) samples, with the former being higher, than in unprocessed semen samples (53.1 ± 3.7%). The recovery rate of progressive motile sperms was significantly lower in swim-up-(9.7 ± 1.4%) than in density gradient centrifugation-processed samples (17.2 ± 1.8%, p < 0.05). Conclusions: The swim-up method is superior to density gradient centrifugation, evidenced by less sperm DNA fragmentation and higher sperm progressive motility. The recovery rate of progressive motile sperms was better after density gradient centrifugation than after swim-up.

Research progress on the effect of sperm chromatin integrity on function and its detection methods.

Sperm chromatin not only carries genetic information such as paternal DNA, but also carries structural proteins, epigenetic information, and higher-order chromatin structures (such as matrix attachment regions and telomeres), etc. These information play an important role in embryonic development. This article mainly reviews the effects of these different information carried by sperm chromatin on sperm function and embryonic development and the research progress of related detection methods, in order to provide a theoretical basis and scientific diagnosis and treatment strategies for the etiology screening of clinical infertility, embryo arrest and recurrent miscarriage, so as to improve the pregnancy outcomes of natural conception and assisted reproduction. Keywords: sperm chromatin; epigenetics; sperm DNA damage; sperm function; higher-order chromatin structures.

Sperm competition increases sperm production and quality in Cataglyphis desert ants.

Sperm competition is a pervasive evolutionary force that shapes sperm traits to maximize fertilization success. Indeed, it has been shown to increase sperm production in both vertebrates and invertebrates. However, sperm production is energetically costly, which may result in trade-offs among sperm traits. In eusocial hymenopterans, such as ants, mating dynamics impose unique selective pressures on ejaculate. Males are sperm limited: they enter adulthood with a fixed amount of sperm that will not be renewed. We explored whether sperm competition intensity was associated with sperm quantity and quality (i.e. sperm viability and DNA fragmentation) in nine Cataglyphis desert ants. Our results provide phylogenetically robust evidence that sperm competition is positively correlated with sperm production and sperm viability. However, it was unrelated to sperm DNA integrity, indicating the absence of a trade-off involving this trait. These findings underscore that sperm competition may strongly mould sperm traits and drive reproductive performance in eusocial Hymenoptera.

Low levels of mouse sperm chromatin fragmentation delay embryo development.

We previously demonstrated that MnCl2 induces double-stranded DNA breaks in sperm in a process that we term as sperm chromatin fragmentation. Here, we tested if the levels of double-stranded DNA breaks were corelated to the concentration of MnCl2, and we compared this to another agent that causes single-stranded DNA breaks, H2O2. We found that both methods have the advantage of inducing DNA breaks in a concentration-dependent manner. Mouse sperm were treated with varying concentrations of either H2O2 or MnCl2, and the DNA damage was assessed by pulse-field gel electrophoresis, and the alkaline and neutral comet assays. Oocytes were injected with either treated sperm and the resulting embryos analyzed with an embryoscope to detect subtle changes in embryonic development. We confirmed that H2O2 treatment induced primarily single-stranded DNA breaks and MnCl2 induced primarily double-stranded DNA breaks, indicating different mechanisms of damage. These sperm were injected into oocytes, and the development of the resulting embryos followed with an embryoscope equipped with time lapse recording. We found that aberrations in early embryonic development by day 2 with even the lowest levels of DNA damage and that the levels of embryonic aberrations correlated to the concentration of either H2O2 or MnCl2. Low levels of H2O2 caused significantly more aberrations in embryonic development than low levels of MnCl2 even though the levels of DNA damage as measured by comet assays were similar. These data demonstrate that even low levels of sperm DNA damage cause delays and arrests in embryonic development.

Investigation on the mechanisms of human sperm DNA damage based on the proteomics analysis by SWATH-MS.

BACKGROUND: Spermatozoa have the task of delivering an intact paternal genome to the oocyte and supporting successful embryo development. The detection of sperm DNA fragmentation (SDF) has been emerging as a complementary test to conventional semen analysis for male infertility evaluation, but the mechanism leading to SDF and its impact on assisted reproduction remain unclear. Therefore, the study identified and analyzed the differentially expressed proteins of sperm with high and low SDF. METHODS: Semen samples from men attended the infertility clinic during June 2020 and August 2020 were analyzed, and sperm DNA fragmentation index (DFI) was detected by the sperm chromatin structure assay. Semen samples with low DFI (< 30%, control group) and high DFI (≥ 30%, experimental group) were optimized by density gradient centrifugation (DGC), and the differentially expressed proteins of obtained sperm were identified by the Sequential Window Acquisition of All Theoretical Mass Spectra Mass Spectrometry (SWATH-MS) and performed GO and KEGG analysis. RESULTS: A total of 2186 proteins were identified and 1591 proteins were quantified, of which 252 proteins were identified as differentially expressed proteins, including 124 upregulated and 128 downregulated. These differentially expressed proteins were involved in metabolic pathways, replication/recombination/repair, acrosomal vesicles, kinase regulators, fertilization, tyrosine metabolism, etc. Western blotting results showed that the expression levels of RAD23B and DFFA proteins and the levels of posttranslational ubiquitination and acetylation modifications in the experimental group were significantly higher than those in the control group, which was consistent with the results of proteomics analysis. CONCLUSIONS: Proteomic markers of sperm with high DNA fragmentation can be identified by the SWATH-MS and bioinformatic analysis, and new protein markers and posttranslational modifications related to sperm DNA damage are expected to be intensively explored. Our findings may improve our understanding of the basic molecular mechanism of sperm DNA damage.

Male reproductive ageing: a radical road to ruin.

In modern post-transition societies, we are reproducing later and living longer. While the impact of age on female reproductive function has been well studied, much less is known about the intersection of age and male reproduction. Our current understanding is that advancing age brings forth a progressive decline in male fertility accompanied by a reduction in circulating testosterone levels and the appearance of age-dependent reproductive pathologies including benign prostatic hypertrophy and erectile dysfunction. Paternal ageing is also associated with a profound increase in sperm DNA damage, the appearance of multiple epigenetic changes in the germ line and an elevated mutational load in the offspring. The net result of such changes is an increase in the disease burden carried by the progeny of ageing males, including dominant genetic diseases such as Apert syndrome and achondroplasia, as well as neuropsychiatric conditions including autism and spontaneous schizophrenia. The genetic basis of these age-related effects appears to involve two fundamental mechanisms. The first is a positive selection mechanism whereby stem cells containing mutations in a mitogen-activated protein kinase pathway gain a selective advantage over their non-mutant counterparts and exhibit significant clonal expansion with the passage of time. The second is dependent on an age-dependent increase in oxidative stress which impairs the steroidogenic capacity of the Leydig cells, disrupts the ability of Sertoli cells to support the normal differentiation of germ cells, and disrupts the functional and genetic integrity of spermatozoa. Given the central importance of oxidative stress in defining the impact of chronological age on male reproduction, there may be a role for antioxidants in the clinical management of this process. While animal studies are supportive of this strategy, carefully designed clinical trials are now needed if we are to realize the therapeutic potential of this approach in a clinical context.