Glucocorticoids improve sperm performance in physiological and pathological conditions: their role in sperm fight/flight response

Glucocorticoids play a physiologic role in the adult male reproductive functions, modulating gonadal steroid synthesis and spermatogenesis, through the glucocorticoid receptor (GR). The expression of GR has been described in several key testicular cell types, including somatic cells and early germ cell populations. Nothing is known on GR in human spermatozoa. Herein, we explored the GR expression and its possible role in normal and testicular varicocele semen samples from volunteer donors. After semen parameter evaluation by macro- and microscopic analysis, samples were centrifuged; then spermatozoa and culture media were recovered for further investigations. By western blotting and immunofluorescence analyses we evidenced for the first time in spermatozoa the presence of GR-D3 isoform which was reduced in sperm from varicocele patients. By treating sperm with the synthetic glucocorticoid dexamethasone (DEXA), we found that survival, motility, capacitation, and acrosome reaction were increased in both healthy and varicocele samples. GR involvement in mediating DEXA effects, was confirmed by using the GR inhibitor mifepristone (M2F). Worthy, we also discovered that sperm secretes different cortisol amounts depending on its physio-pathological status, suggesting a defence mechanism to escape the immune system attach in the female genital tract thus maintaining the immune-privilege as in the testis. Collectively, our data suggests a role for glucocorticoids in determining semen quality and function, as well as in participating on sperm immune defensive mechanisms. The novelty of this study may be beneficial and needs to take into account in artificial insemination/drug discovery aimed to enhancing sperm quality.

Evaluation of the effects of hydroxytyrosol on human sperm parameters during cryopreservation

Human sperm cryopreservation is a routine procedure in assisted reproductive technology, but it has detrimental effects on different sperm parameters due to oxidative stress. Our objective was to assess the impacts of hydroxytyrosol (HT), as an antioxidant, on human sperm parameters following cryopreservation. In the first phase, 20 normal human semen samples were cryopreserved using the rapid freezing method with different concentrations of HT including 0, 50, 100, 150, and 200 μg/mL. In the second phase, 20 normal semen samples were collected and cryopreserved with 50 and 100 μg/mL HT. The beneficial effects of HT were determined by evaluation of motility (computer-assisted sperm analysis; CASA), viability (Eosin-nigrosine stain), DNA integrity (sperm chromatic dispersion test, SCD), reactive oxygen species (DCF and DHE staining by flowcytometry) lipid peroxidation (malondialdehyde, MDA test) and mitochondrial membrane potential (JC1 staining by flowcytometry) of sperm after cryopreservation. After thawing, sperm motility had an increasing trend in 50 and 100 μg/mL HT groups in comparison with other groups, althought the difference was not significant. However, sperm viability was significantly increased at 50 and 100 μg/mL HT. Our data also showed that sperm DNA fragmentation was significantly decreased after thawing at 100 μg/mL in comparison with 0 and 50 μg/mL HT. However, the level of intracellular reactive oxygen species, lipid peroxidation and mitochondrial membrane potential were not significantly different between groups. Our results showed that HT may have protective effects on the viability and DNA integrity of human sperm during the freezing-thawing process.

Evaluation of the effect of mitoquinone on functional parameters, DNA structure, and genes expression related to the apoptotic and antioxidants of human sperm after freezing-thawing

OBJECTIVE

Sperm freezing is considered as an effective way in assisted reproductive technology (ART) programs, it has detrimental effects on sperm function, due to the production of reactive oxygen species (ROS). This study aimed to investigate the potential of Mitoquinone (MitoQ) in inhibiting the production of mitochondrial ROS during sperm freezing.

METHODS

A total of 20 human normozoosperm samples were collected for this study. The samples were divided into four groups, each containing different concentrations of MitoQ (0, 0.2, 2, and 20 nM), and then subjected to the freezing process. After thawing, the sperm suspensions were evaluated for parameters including motility, morphology, acrosome integrity, adenosine triphosphate (ATP) level, intracellular ROS, viability, chromatin packaging, DNA denaturation, DNA fragmentation, as well as the expression of antioxidants (GPX, SOD) and apoptotic (Bax, Bcl2) genes.

RESULTS

The results showed that total and progressive mobility of sperms significantly increased in the 2 nM group, while significantly decreased in the 20 nM group (p ≤ 0.05). Sperm morphology did not significantly improve across all the tested concentrations (p ≥ 0.05). Intracellular ROS levels showed a significant decrease and increase in the concentrations of 2 and 20 nM, respectively (p ≤ 0.05). Furthermore, a significant increase was observed in viability, ATP, acrosome integrity, chromatin packaging, and non-denatured and non-fragmented DNA after treatment with 2 nM of MitoQ, compared with the control group (p ≤ 0.05). Regarding gene expressions, the relative expressions of oxidative stress genes were increased in the 2 nM group and decreased in the 20 nM group (p ≤ 0.05), while no significant difference was observed in the expressions of apoptotic genes compared with the control group (p ≥ 0.05). All the comparisons were made with respect to the control group.

CONCLUSION

Adding the optimal concentration of MitoQ (2 nM) to the sperm freezing medium not only improves sperm functional parameters and reduces DNA damages, but also stimulates the expression of antioxidant genes, leading to even greater benefits for sperm cryopreservation.

Graphene oxide had adverse effects on sperm motility and morphology through oxidative stress

Graphene oxide (GO) is a new type of graphene material, but its effects on the male reproductive system are unclear. Here, we investigated the effects of GO on human sperm in vitro. Sperms were incubated with various doses of GO (0, 10, 20, or 40 μg/mL) for different times (1, 3, or 6 h) at 37 °C, followed by analyses of the sperm motility, viability, abnormalities, and DNA fragmentations. GO exposure significantly decreased sperm motility and viability, increased sperm abnormalities, and DNA fragmentation. Moreover, GO exposure resulted in a significant reduction of sperm mitochondrial membrane potential (MMP), which was confirmed by the ultrastructural changes of chromatin and mitochondria caused by GO. These data revealed the adverse effects of GO on sperm. Further research showed that GO exposure led to a significant increase in malondialdehyde (MDA) and reactive oxygen species (ROS) in sperm cells and a significant decrease in total superoxide dismutase (T-SOD) and glutathione peroxidase (GSH-Px). In addition, western blot analysis showed that the levels of Nrf-2 and HO-1 protein expression in GO-treated sperm cells were significantly increased compared to the control. These results indicated that GO had adverse effects on human sperm through oxidative stress, which was associated with Nrf-2/HO-1 signaling pathway.

Apelin is found in human sperm and testis and is raised in inflammatory pathological conditions

Apelin/APJ receptor (R) is involved in many oxidative stress-induced pathological conditions. Since this system is not yet explored in male reproduction, we studied apelin/APJ-R in human semen and testis. Semen of 41 infertile patients with varicocele, genitourinary infections, unexplained infertility and 12 fertile men was analysed (WHO guidelines, 2021). Apelin was quantified by ELISA in seminal fluid and spermatozoa, interleukin (IL)-1β in seminal fluid. Apelin/APJ-R were immunolocalized in spermatozoa and testis. Apelin was present in spermatozoa and its levels were negatively correlated with normal sperm morphology% (r = -0.857; p < 0.001), and positively with IL-1β levels (r = 0.455; p < 0.001). Apelin and IL-1β concentrations were increased in patients' samples with varicocele (apelin p < 0.01; IL-1β p < 0.05) and infections (apelin p < 0.01; IL-1β p < 0.001). By logistic regression analysis, apelin (OR 1.310; p = 0.011) and IL-1β (OR 1.572; p = 0.005) were predictors of inflammatory diseases (varicocele, infections). Apelin and APJ-R immunofluorescence labels were weak in sperm tail of fertile men and intense along tail, cytoplasmic residues and post-acrosomal sheath of sperm from infertile men. In testis, apelin and APJ-R labels were evident in Leydig cells and weak inside the seminiferous tubule. Apelin/APJ-R system is present in human spermatozoa and testicular tissue and probably involved in human fertility.

Hexachlorocyclohexane impairs human sperm motility by affecting lysine glutarylation and mitochondrial functions

Decreased sperm motility is a leading cause of male infertility and persistent organic pollutants are known to contribute significantly to the development of this disease. The effects of organochlorine pesticides such as hexachlorocyclohexane (HCH) on human sperm function and their mechanisms of action have received much attention, but are still not fully understood. Herein, we discovered that HCH has a concentration- and time-dependent inhibitory effect on human sperm motility in vitro. Moreover, HCH could reduce the levels of lysine glutarylation (Kglu) and glucose-6-phosphate dehydrogenase activity in sperm. Meanwhile, HCH could increase reactive oxygen species and thereby lead to mitochondrial depolarization and the down-regulation of adenosine triphosphate levels. In particular, we observed that sodium glutarate (Na-glu), the precursor of glutaryl-CoA, could alleviate the inhibitory effect of HCH on sperm Kglu levels, whereas the ROS scavenger N-acetyl-L-cysteine (NAC) had no effect. Intriguingly, both Na-glu and NAC were able to partially inhibit the HCH-induced increase in sperm ROS levels and impaired sperm motility. In conclusion, we propose that HCH inhibits sperm Kglu, leading to the disruption of mitochondrial energy metabolism, which in turn adversely affects sperm motility.

A pilot study of LINE-1 copy number and telomere length with aging in human sperm

PURPOSE

Unlike other cells in the body, in sperm, telomere length (TL) increases with age. TL can regulate nearby genes, and the subtelomeric region is rich in retrotransposons. We hypothesized that age-related telomere lengthening in sperm might suppress Long Interspersed Element 1 (LINE-1/L1), the only competent retrotransposon in humans.

METHODS

We measured L1 copy number (L1-CN) and sperm telomere length (STL) from young and older men to evaluate the relationship between age, TL and L1-CN. We also evaluated L1-CN and TL in individual sperm to determine whether these variables influence sperm morphology. STL was assayed by Multiplex quantitative polymerase chain reaction method (mmqPCR) and L1-CN by Quantitative polymerase chain reaction (qPCR).

RESULTS

We found that STL increased, and L1-CN decreased significantly with paternal age. STL in normal single sperm was significantly higher than in abnormal sperm. L1-CN did not differ between normal and abnormal sperm. Furthermore, morphologically normal sperm have longer telomeres than abnormal sperm.

CONCLUSIONS

Elongation of telomeres in the male germline could repress retrotransposition, which tends to increase with cellular aging. More studies in larger cohorts across a wide age span are needed to confirm our conclusions and explore their biological and clinical significance.

Transposon insertion profiling by sequencing (TIPseq) identifies novel LINE-1 insertions in human sperm

PURPOSE

Long interspersed nuclear element-1 (LINE-1 or L1) comprises 17% of the human genome. Retrotransposons may perturb gene integrity or alter gene expression by altering regulatory regions in the genome. The germline employs a number of mechanisms, including cytosine methylation, to repress retrotransposon transcription throughout most of life. Demethylation during germ cell and early embryo development de-represses retrotransposons. Intriguingly, de novo genetic variation appearing in sperm has been implicated in a number of disorders in offspring, including autism spectrum disorder, schizophrenia, and bipolar disorder. We hypothesize that human sperm exhibit de novo retrotransposition and employ a new sequencing method, single cell transposon insertion profiling by sequencing (scTIPseq) to map them in small amounts of human sperm.

METHODS

Cross-sectional case-control study of sperm samples (n=10 men; ages 32-55 years old) from consenting men undergoing IVF at NYU Langone Fertility Center. scTIPseq identified novel LINE-1 insertions in individual sperm and TIPseqHunter, a custom bioinformatics pipeline, compared the architecture of sperm LINE-1 to known LINE-1 insertions from the European database of Human specific LINE-1 (L1Hs) retrotransposon insertions (euL1db).

RESULTS

scTIPseq identified 17 novel insertions in sperm. New insertions were mainly intergenic or intronic. Only one sample did not exhibit new insertions. The location or number of novel insertions did not differ by paternal age.

CONCLUSION

This study for the first time reports novel LINE-1 insertions in human sperm, demonstrating the feasibility of scTIPseq, and identifies new contributors to genetic diversity in the human germ line.

ATP increases head volume in capacitated human sperm via a purinergic channel

Scanning ion-conductance microscopy allowed us to document an external Ca²⁺ dependent ATP driven volume increase (ATPVI) in capacitated human sperm heads. We examined the involvement of purinergic receptors (PRs) P2X2R and P2X4R in ATPVI using their co-agonists progesterone and Ivermectin (Iver), and Cu²⁺, which co-activates P2X2Rs and inhibits P2X4Rs. Iver enhanced ATPVI and Cu²⁺ and 5BDBD inhibited it, indicating P2X4Rs contributed to this response. Moreover, Cu²⁺ and 5BDBD inhibited the ATP-induced acrosome reaction (AR) which was enhanced by Iver. ATP increased the concentration of intracellular Ca²⁺ ([Ca²⁺]_i) in >45% of individual sperm, most of which underwent AR monitored using FM4-64. Our findings suggest that human sperm P2X4R activation by ATP increases [Ca²⁺]_i mainly due to Ca²⁺ influx which leads to a sperm head volume increase, likely involving acrosomal swelling, and resulting in AR.

The effects of purslane (Portulaca oleracea) and fennel (Foeniculum vulgare Mill) hydroalcoholic extracts on the functional parameters of human spermatozoa after vitrification

OBJECTIVE

Reactive oxygen species (ROS) are produced during cryopreservation of human sperm and impair sperm function. Antioxidant compounds, such as fennel and purslane, reduce the damaging effects of ROS. This study aimed to evaluate motility parameters, plasma membrane integrity (PMI), mitochondrial membrane potential (MMP), intracellular ROS, and DNA damage to determine the optimum concentrations of hydroalcoholic extracts of fennel and purslane for human spermatozoa cryopreservation.

METHODS

Twenty human sperm samples were used and divided into seven equal groups consisting of fennel hydroalcoholic extract (5, 10, and 15 mg/L), purslane hydroalcoholic extract (25, 50, and 100 mg/L), and no additive.

RESULTS

Supplementation of 25 mg/L and 50 mg/L purslane extract and 10 mg/L fennel extract in cryopreservation extender significantly increased the motility and PMI of sperm with a significant reduction in intracellular ROS compared to control groups (p<0.05). A 50 mg/L concentration of purslane extract elevated progressive motility and MMP compared to the control group (p<0.05). No significant differences were seen for motion patterns and DNA damage of frozen-thawed human sperm in extender containing these extracts.

CONCLUSION

The results showed that supplementation of 50 mg/L purslane extract and 10 mg/L fennel extract in semen cryopreservation extender has the potential to decrease intracellular ROS and subsequently elevate the motility and PMI of human sperm.

Paternal exposure to arsenic and sperm DNA methylation of imprinting gene Meg3 in reproductive-aged men

BACKGROUND

Prenatal exposure to arsenic and mercury have been associated with adverse pregnancy outcomes that might be in part mediated by dynamic modification of imprinting gene that are emerging mechanism.

OBJECTIVES

The objective of this study was to examine the impacts of paternal exposure to arsenic and co-exposure to arsenic and mercury on human sperm DNA methylation status of imprinting genes, respectively.

METHODS

A total of 352 male subjects (23-52 years old) were recruited and demographic data were obtained through questionnaires. Urinary arsenic and mercury levels were measured using hydride generation-atomic fluorescence spectrometer. Multivariate regression model was employed to investigate the relationship between urinary arsenic levels and sperm DNA methylation status at H19, Meg3 and Peg3, measured by pyrosequencing, and evaluating the interaction with mercury.

RESULTS

After adjusting potential confounds factors by multivariate regression model, the results indicated a significantly positive relationship between urinary arsenic levels and the methylation status of Meg3 at both mean level (β =  + 0.125, p < 0.001) and all individual CpGs, i.e., CpG1 (β =  + 0.094, p < 0.001), CpG2 (β =  + 0.132, p < 0.001), CpG3 (β =  + 0.121, p < 0.001), CpG4 (β =  + 0.142, p < 0.001), CpG5 (β =  + 0.111, p < 0.001), CpG6 (β =  + 0.120, p < 0.001), CpG7 (β =  + 0.143, p < 0.001), CpG8 (β =  + 0.139, p < 0.001) of Meg3 DMRs. The interaction effects analysis indicated the interaction effects of arsenic and mercury on Meg3 were not existing.

CONCLUSIONS

Paternal nonoccupational exposure to arsenic induces the altered DNA methylation status of Meg3 in human sperm DNA. In addition, the interaction effects of arsenic and mercury on Meg3 were not existing. These findings would implicate the sensibility of sperm epigenome for environmental pollutions.

Microcystin leucine arginine induces human sperm damage: Involvement of the Ca2+/CaMKKβ/AMPK pathway

As a common pollutant in the water environment, microcystin leucine arginine (MC-LR) can enter semen and damage the sperm in animals. However, the mechanism by which MC-LR damages human sperm is unclear. Therefore, human sperm samples were obtained from the Henan Provincial Sperm Bank and exposed to different concentrations (0, 1, 10, and 100 μg/L) of MC-LR for 1, 2, 4, and 6 h, to invegest the effects and potential mechanism of MC-LR on sperm. The results showed that MC-LR mainly accumulated in the neck and flagellum of human sperm. Compared to the control group, the sperm capacitation rate and motility were significantly decreased in the 100 μg/L group. After exposure of 100 μg/L of MC-LR, the central microtubule and microtubule doublet of sperm flagellum were blurred, asymmetrical, or even lost. Furthermore, the expression levels of flagellin DNAH17, SPEF2, SPAG16, SPAG6, and CFAP44 in human sperm were reduced. Also, the phosphorylation levels of CaMKKβ and AMPK can be inhibited by MC-LR. These findings revealed that MC-LR can induce functional and structural damage in human sperm, and the Ca²⁺/CaMKKβ/AMPK pathway may be involved in this process. This study will provide a basis for prevention and treatment of male fertility declines caused by MC-LR.

Multiple flow cytometry analysis for assessing human sperm functional characteristics

Multiparametric analysis by flow cytometry solves one of the major problems in sperm evaluation, the inability to test multiple attributes simultaneously in a single cell, which would increase the precision to predict fertility potential since several sperm parameters are tested. The association of fluorochromes and compounds conjugated to fluorochromes in multiparametric sperm analysis is well-established in microscopy techniques. However, these techniques are subjective and limit the assessment in small cell numbers, thereby harming analytic accuracy. Therefore, the current study aimed to present new possibilities for assessing the integrity and stability of the sperm plasma membrane, acrosome status, mitochondrial potential, and superoxide anion production in the mitochondrial matrix in only 2 cytometric assays using cytometers equipped with 2 and 3 lasers. For this, human semen samples collected by masturbation and selected by the swim-up technique were divided into 3 treatments: T0 (flash-frozen semen), T50 (flash-frozen semen + fresh semen, V: V), and T100 (fresh semen) for the validation of the multiparametric protocols by flow cytometry. For both protocols, sperm percentage with positive stain for all fluorophores differed significantly between treatments. The determination coefficients presented values close to 1, which validated objective, sensitive, rapid, and reproducible methodologies. Therefore, we concluded that the results reflect the status of analyzed structure, enabling a more accurate diagnosis of male infertility that has become an increasingly prevalent worldwide setback due to exposure to a variety of environmental toxicants.

SP22 sperm protein as a potential biomarker of fertility in humans: A preliminary study

Infertility affects approximately 15% of couples of reproductive age, and 50% of the cases are directly related to men. The evaluation of male fertility is based on analyses of routine seminal parameters and the use of more advanced techniques can help identify fertility biomarkers. SP22 sperm protein is considered a biomarker in murine species since its concentration is highly correlated with sperm fertility. As the role of this protein as a biomarker is already well-established in other species, we hypothesized that this same correlation could apply to human. Thus, the present study aimed to investigate possible correlations between SP22 concentration and sperm parameters in fertile and infertile men. For this, a study was carried out on 21 volunteers' seminal samples who were grouped according to fertility as fertile (n = 10) or infertile (n = 11). Conventional and functional sperm analyses, membrane protein extraction, quantification and immunolocalization of SP22 were performed. The infertile volunteers showed an increase in the percentage of sperm with abnormalities in head morphology and a decrease in the percentage of sperm with intact plasma membrane and damaged acrosomal membrane. Serum concentration of the hormone SHBG was also decreased in infertile volunteers. The damage to the plasma membrane was positively correlated with the superoxide anion production. Although none of the functional parameters were correlated with SP22 concentration, type D sperm motility was negatively correlated and type A+B sperm motility was positively correlated. This preliminary study opens new paths in the characterization of SP22 as a non-invasive biomarker for predicting fertility/infertility.

A comprehensive investigation of human endogenous retroviral syncytin proteins and their receptors in men with normozoospermia and impaired semen quality

PURPOSE

The study aims to investigate first the presence of Syncytin 2 and its receptor, MFSD2, in human sperm, and second whether the expressions of Syncytin 1, Syncytin 2, and their receptors, SLC1A5 and MFSD2, differ between normozoospermic, asthenozoospermic, oligozoospermic, and oligoasthenozoospermic human sperm samples.

METHODS

The localization patterns and expression levels of syncytins and their receptors were evaluated in normozoospermic (concentration = 88.9 ± 5.5 × 10⁶, motility = 79.2 ± 3.15%, n = 30), asthenozoospermic (concentration = 51.7 ± 7.18 × 10⁶, motility = 24.0 ± 3.12%, n = 15), mild oligozoospermic (concentration = 13.5 ± 2.17 × 10⁶, motility = 72.1 ± 6.5%, n = 15), moderate oligozoospermic (concentration = 8.4 ± 3.21 × 10⁶, motility = 65.1 ± 8.9%, n = 15), severe oligozoospermic (concentration = 2.1 ± 1.01 × 10⁶, motility = 67.5 ± 3.2%, n = 15), and oligoasthenozoospermic (concentration = 5.5 ± 3.21 × 10⁶, motility = 18.5 ± 1.2%, n = 15) samples by immunofluorescence staining and western blot.

RESULTS

Syncytins and their receptors visualized by immunofluorescence showed similar staining patterns with slight staining of the tail in all spermatozoa regardless of normozoospermia, asthenozoospermia, oligozoospermia, or oligoasthenozoospermia. The localization patterns were categorized as equatorial segment, midpiece region, acrosome, and post-acrosomal areas. The combined staining patterns were also detected as acrosomal cap plus post acrosomal region, the midpiece plus equatorial segment, and midpiece plus acrosomal region. However, some sperm cells were categorized as non-stained. Both syncytin proteins were most intensely localized in the midpiece region, while their receptors were predominantly present in the midpiece plus acrosomal region. Conspicuously, syncytins and their receptors showed decreased expression in asthenozospermic, oligozoospermic, and oligoasthenozoospermic samples compared to normozoospermic samples.

CONCLUSION

The expression patterns of HERV-derived syncytins and their receptors were identical regardless of the spermatozoa in men with normozoospermia versus impaired semen quality. Further, asthenozoospermia, oligozoospermia, and oligoasthenozoospermia as male fertility issues are associated with decreased expression of both syncytins and their receptors.

Effects of Radiofrequency Electromagnetic Field (RF-EMF) exposure on male fertility and pregnancy and birth outcomes: Protocols for a systematic review of experimental studies in non-human mammals and in human sperm exposed in vitro

BACKGROUND

Radiofrequency Electromagnetic Fields (RF-EMF) at environmental level have been reported to induce adverse effects on the male reproductive system and developing embryos. However, despite the number of experiments conducted since the 1970s, the diversity of testing approaches and exposure conditions, inconsistencies among results, and dosimetric flaws have not yet permitted a solid assessment of the relationship between RF-EMF exposure and such effects, warranting a more systematic and methodologically rigorous approach to the evaluation of available data.

OBJECTIVES

This study aims at evaluating the effects of RF-EMF exposure on male fertility and pregnancy outcomes by a systematic review (SR) of experimental studies, conducted in compliance with international guidelines. The evidence will be organized into three streams: 1) Studies evaluating the impact of RF-EMF on the male reproductive system of experimental mammals; 2) studies evaluating the impact of RF-EMF on human sperm exposed in vitro; 3) studies evaluating the impact of RF-EMF on adverse pregnancy, birth outcomes and delayed effects in experimental mammals exposed in utero.

STUDY ELIGIBILITY AND CRITERIA

Eligible studies will include peer-reviewed articles reporting of original results about effects of controlled exposures to RF-EMF in the frequency range 100 kHz-300 GHz on the selected outcomes without any language or year-of-publication restrictions. Eligible studies will be retrieved by calibrated search strings applied to three electronic databases, PubMed, Scopus and EMF Portal and by manual search of the list of references of included papers and published reviews.

STUDY APPRAISAL AND SYNTHESIS METHOD

The internal validity of the studies will be evaluated using the Risk of Bias (RoB) Rating Tool developed by National Toxicology Program/Office of Health Assessment and Translation (NTP/OHAT) integrated with input from the SYRCLE RoB tool. Given sufficient commensurate data, meta-analyses will be performed, otherwise narrative syntheses will be produced. Finally, the certainty of the effects of RF-EMF exposure on male fertility and pregnancy and birth outcomes will be established following GRADE.

FUNDING

The study is financially supported by the World Health Organization.

REGISTRATION

OSF Registration DOI https://doi.org/10.17605/OSF.IO/7MUS3; PROSPERO CRD42021227729, CRD42021227746.

Proteomics study reveals the molecular mechanisms underlying cryotolerance induced by mild sublethal stress in human sperm

The preconditioning of human sperm with sublethal nitrosative stress before cryopreservation can potentially improve the thawed sperm quality. However, the underlying mechanisms behind this protective strategy are not entirely understood. We compared the cryosurvival of human sperm exposed to 0.01 μM nitric oxide (NO) throughout the cryopreservation and used multiplexed quantitative proteomics approach to identify changes in the proteome profile of preconditioned sperm cells. Semen samples were obtained from 30 normospermia donors and then each sample was divided into three equal parts: fresh (F), frozen-control (C), and frozen exposed to nitric oxide (NO). The sperm undergoing mild sublethal stress showed higher values for motility and viability compared to the frozen control sperm. Moreover, out of 2912 identified proteins, 248 proteins were detected as differentially abundant proteins (DAPs) between cryopreserved groups and fresh group (F) (p < 0.05). Gene ontology (GO) analysis of differentially abundant proteins indicated that the abundance of proteins associated with glycolysis, gluconeogenesis, and fertilization processes was reduced while oxidative phosphorylation pathway was increased in abundance in cryopreserved sperm compared to the fresh sperm. Moreover, redox protein such as thioredoxin 17 was increased in abundance in the NO group compared to the control freezing group. Therefore, the pre-conditioning of sperm prior to cryopreservation may play an important role in maintaining the redox balance in mitochondria of sperm after freezing. Overall, our results indicate that arylsulfatase A (ARSA), serine protease 37 (PRSS37), and sperm surface protein (SP17) may potentially serve as protein biomarkers associated with screening the fertilization potential of the thawed sperm.

Complex combined steroid mix of the female tract modulates human sperm

Human spermatozoa interact with a complex biochemical environment in the female reproductive tract en route to the site of fertilisation. Ovarian follicular fluid contributes to this complex milieu and is known to contain steroids such as progesterone, whose effects on sperm physiology have been widely characterised. We have previously reported that progesterone stimulates intracellular calcium concentration ([Ca²⁺]_i) signalling and acrosome reaction in human spermatozoa. To characterise the effects of the unified complete follicular fluid steroid hormone complement on human spermatozoa, a comprehensive, data-based, 'physiological standard' steroid hormone balance of follicular fluid (shFF) was created from individual constituents. shFF induced a rapid biphasic [Ca²⁺]_i elevation in human spermatozoa. Using population fluorimetry, we compared [Ca²⁺]_i signal amplitude in cells exposed to serial applications of shFF (6 steps from 10^-5X up to 1X shFF) with responses to the equivalent progesterone component alone (6 steps from 135 pM - 13.5μM). Threshold for the response to shFF was right-shifted (≈10-fold) compared to progesterone alone, but the maximum response to shFF was greatly enhanced. An acrosome reaction assay was used to assess functional effects of shFF-induced sperm calcium signalling. shFF as well as progesterone-treated spermatozoa showed a significant increase in % acrosome reaction (P < 0.01). All of this evidence suggests the modulation of progesterone-mediated responses by other follicular fluid steroids.

The cryoprotective effect of vitamins on human spermatozoa quality: a systematic review and meta-analysis

The Cryopreservation of spermatozoa ensures preserving fertility potential after some medical treatments such as chemotherapy and radiotherapy in cancer patients. However, many spermatozoa encounter serious damages, and their motility and viability decrease considerably after thawing. The excessive production of reactive oxygen species is one of the major causes of these damages. The supplementation of cryopreservation media with vitamins, which are well-known antioxidants, can reduce cryopreservation-induced damages. In this systematic review, we aimed to evaluate the cryoprotective effect of various vitamins on the quality of cryopreserved-thawed human spermatozoa. Two researchers searched PubMed, ISI, and Scopus databases up to March 2020. All original articles using vitamins in human spermatozoa cryopreservation media were included. We used a standardized form to extract sample size and to determine sample quality, the type and dose of vitamins, and the cryopreservation methods and their effects. We performed a meta-analysis on studies with available data (Mean + SD in cryoprotectant and cryoprotectant + cryoprotectant groups). We also performed a test of between-study heterogeneity, subgroup analysis, and meta-regression. Out of 258 studies, 16 articles were included for the analysis. Our meta-analysis revealed that using vitamins in cryopreservation media could increase motility by 4.60% (95% CI 6.16, 3.05; P = 0.0001), viability by 5.71% (95% CI 9.71, 1.72; P = 0.0001), and DNA integrity by 10.20% (95% CI 12.98, 7.42; P = 0.0001) in cryopreserved-thawed spermatozoa. We found a significant correlation between using vitamins and improved spermatozoa quality; the sperm motility and viability were improved and DNA fragmentation was reduced after thawing by vitamins. However, we could not emphasize on any type or dose of vitamins but we conclude that the anti-oxidative function of vitamins is the main reason for these benefits.

Impaired transcription of human endogenous retroviruses in the sperm with exception of syncytin 1: short communication

BACKGROUND

Human endogenous retroviruses (HERVs), remnants of ancestral infections, represent 8% of the human genome. HERVs are co-opted for important physiological functions during embryogenesis; however, little is known about their expression in human gametes. We evaluated the transcriptional levels of several retroviral sequences in human spermatozoa.

METHODS AND RESULTS

We assessed, through a Real-Time PCR assay, the transcription levels of the pol genes of HERV-H, -K and -W families and of env genes of syncytin (Syn)1 and Syn2 in the spermatozoa from 8 normospermic subjects. The entity and distribution of their expressions were compared to values found in white blood cells (WBCs) from 16 healthy volunteers. The level of HERV transcripts was significantly lower in spermatozoa than in WBCs for HERV-H-pol, HERV-K-pol, HERV-W-pol, and Syn2.In contrast, the level of expression of Syn1 in the sperm was similar to that found in WBCs and it was significantly higher than the mRNA concentrations of other HERV genes in spermatozoa.

CONCLUSIONS

Our findings show, for the first time, the presence of several retroviral mRNAs in the sperm, although in low amounts. The higher concentration of Syn1 suggests that it could play a key role in the fusion process between gametes during fertilization and, perhaps, be involved in embryo development. Further studies could clarify whether aberrant HERV expressions, in particular of Syn1, negatively affect fertilization and embryo growth and whether sperm manipulation procedures, such as cryopreservation, may potentially influence HERV transcription in the human male gamete.

Membrane lipid replacement with nano-micelles in human sperm cryopreservation improves post-thaw function and acrosome protein integrity

RESEARCH QUESTION

Membrane lipid replacement (MLR) of oxidized membrane lipids can restore sperm cellular membrane functionality and help improve surface protein stability during cryopreservation. What are the effects of MLR with nano-micelles made from a glycerophospholipid (GPL) mixture and cholesterol-loaded cyclodextrin (CLC), on the cryosurvival and expression of acrosome-related proteins in thawed human spermatozoa?

DESIGN

Twenty samples were used to determine the optimum level of nano-micelles by incubation of semen with different concentrations of GPL (0.1 and 1%) and CLC (1 and 2 mg/ml) (including GPL-0.1, GPL-1, CLC-1, CLC-2, CLC-1/GPL-0.1, CLC-2/GPL-0.1, CLC-1/GPL-1 and CLC-2/GPL-1) before cryopreservation. Then, 30 semen samples were collected, and each sample was divided into the following three aliquots: fresh, frozen control and frozen incubated with optimum level of nano-micelles (0.1% GPL and 1 mg/ml CLC).

RESULTS

CLC-1/GPL-0.1 and GPL-0.1 significantly increased motility parameters. CLC-1, GPL-0.1 and CLC-1/GPL-0.1 significantly improved viability rate compared with frozen control group. Significantly higher mitochondrial activity and acrosome integrity, and a lower rate of apoptosis, were observed in the CLC-1/GPL-0.1 compared with the frozen control group. The expression ratios of arylsulfatase A (ARSA), serine protease 37 (PRSS37), serine protease inhibitor Kazal-type 2 (SPINK2) and equatorin (EQTN) significantly increased compared with the frozen control group.

CONCLUSIONS

Modification of membrane cholesterol and GPL mixtures in spermatozoa enhances their acrosome protein integrity by inhibiting early apoptotic changes and spontaneous acrosome reactions.

Different Approaches to Record Human Sperm Exocytosis

Acrosome reaction is an exocytic process that enables a sperm to penetrate the zona pellucida and fertilize an egg. The process involves the fenestration and vesiculation of the sperm plasma membrane and outer acrosomal membrane, releasing the acrosomal content. Given the importance of the acrosome secretion in fertilization, many different methods have been developed to detect the acrosome reaction of sperm. In this chapter, we describe detailed practical procedures to assess the acrosomal status of human spermatozoa. To do this, we resorted to light optical and epifluorescence microscopy, flow cytometry, and transmission electron microscopy. We also itemize the protocol for real-time measurements of the acrosome reaction by confocal microscopy. Further, we discuss the level of complexity, costs, and the reasons why a researcher should choose each technique.This chapter is designed to provide the user with sufficient background to measure acrosomal exocytosis in human sperm.

High mRNA expression of GABA receptors in human sperm with oligoasthenoteratozoospermia and teratozoospermia and its association with sperm parameters and intracytoplasmic sperm injection outcomes

Objective

This study investigated the mRNA expression of gamma-aminobutyric acid (GABA) receptors in the sperm of oligoasthenoteratozoospermic (OAT) and teratozoospermic (TER) men compared to normozoospermic (NOR) men, as well as the relationships between GABA receptor expression and sperm parameters, fertilization rate, and embryo quality.

Methods

The mRNA expression of GABA A-α1 and GABA B-R2 receptors in sperm was examined using reverse transcription–polymerase chain reaction in three groups of patients: NOR (n=32), OAT (n=22), and TER (n=45). The fertilization rate and embryo quality were assessed in 35 patients undergoing intracytoplasmic sperm injection (ICSI; 10 NOR, 10 OAT, and 15 TER men).

Results

OAT men had significantly higher mRNA expression of GABA A-α1 and GABA B-R2 receptors in sperm than NOR men; however, the difference between TER and NOR men was not significant. High levels of these receptors were significantly correlated with low sperm concentration, motility, and morphology, as well as the rate of good-quality embryos (GQEs) at the cleavage stage after ICSI. Patients whose female partners had a >50% GQE rate at the cleavage stage had significantly lower levels of GABA A-α1 receptor expression than those whose partners had a ≤50% GQE rate.

Conclusion

Our findings indicate that mRNA levels of GABA receptors in human sperm are correlated with poor sperm quality and associated with embryo development after ICSI treatment. The GABA A-α1 receptor in sperm has a stronger relationship with embryo quality at the cleavage stage than the GABA B-R2 receptor.

Machine-learning algorithm incorporating capacitated sperm intracellular pH predicts conventional in vitro fertilization success in normospermic patients

OBJECTIVE

To measure human sperm intracellular pH (pH_i) and develop a machine-learning algorithm to predict successful conventional in vitro fertilization (IVF) in normospermic patients.

DESIGN

Spermatozoa from 76 IVF patients were capacitated in vitro. Flow cytometry was used to measure sperm pH_i, and computer-assisted semen analysis was used to measure hyperactivated motility. A gradient-boosted machine-learning algorithm was trained on clinical data and sperm pH_i and membrane potential from 58 patients to predict successful conventional IVF, defined as a fertilization ratio (number of fertilized oocytes [2 pronuclei]/number of mature oocytes) greater than 0.66. The algorithm was validated on an independent set of data from 18 patients.

SETTING

Academic medical center.

PATIENT(S)

Normospermic men undergoing IVF. Patients were excluded if they used frozen sperm, had known male factor infertility, or used intracytoplasmic sperm injection only.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Successful conventional IVF.

RESULT(S)

Sperm pH_i positively correlated with hyperactivated motility and with conventional IVF ratio (n = 76) but not with intracytoplasmic sperm injection fertilization ratio (n = 38). In receiver operating curve analysis of data from the test set (n = 58), the machine-learning algorithm predicted successful conventional IVF with a mean accuracy of 0.72 (n = 18), a mean area under the curve of 0.81, a mean sensitivity of 0.65, and a mean specificity of 0.80.

CONCLUSION(S)

Sperm pH_i correlates with conventional fertilization outcomes in normospermic patients undergoing IVF. A machine-learning algorithm can use clinical parameters and markers of capacitation to accurately predict successful fertilization in normospermic men undergoing conventional IVF.

Quantitative evaluation of human sperm viability using MTT assay: A laboratory study

Background

3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) assay which evaluates cellular mitochondrial activity is widely used for the assessment of cell proliferation and viability.

Objective

This study was performed to assess human sperm viability using MTT assay.

Materials and Methods

In this laboratory study, human-ejaculated semen samples (n = 56 from different donors) were used. The sperm viability was determined using quantitative MTT assay and the sperm motility was assessed according to World Health Organization guidelines. Sperm viability and the correlation between sperm viability and motility were analyzed.

Results

Data revealed a marked positive correlation between MTT reduction rate and the percentage of viable spermatozoa. The Pearson's correlation coefficients also showed a significant correlation between sperm viability and motility.

Conclusion

MTT assay which is based on mitochondrial functionality is a reliable method for evaluating human sperm viability and could be used as a diagnostic test for predicting sperm fertilization ability in clinical settings.

Pentachlorophenol inhibits CatSper function to compromise progesterone's action on human sperm

Pentachlorophenol (PCP), a highly toxic contaminant of chlorophenols, is common in a variety of environments and presents serious risks to animal and human health. However, the reproductive toxicity and potential actions of PCP have not been investigated thoroughly, especially in humans. Here, human spermatozoa were used to evaluate the effect of PCP on cell function and to explore the underlying mechanisms. PCP had no substantive effects on sperm viability or motility, nor on the ability to penetrate viscous medium, sperm hyperactivation or spontaneous acrosome reactions. However, PCP significantly inhibited these properties induced by progesterone (P4). Consistent with the functional observations, although PCP itself did not affect the basal intracellular Ca²⁺ concentrations and CatSper current, PCP dose-dependently inhibited increases of intracellular Ca²⁺ concentrations caused by P4. In addition, the activation of CatSper induced by P4 was largely suppressed by PCP. This is the first report showing that PCP may serves as an antagonist of the P4 membrane receptor to interfere with Ca²⁺ signaling by compromising the action of P4 on regulating sperm function. These findings suggest that the reproductive toxicity of PCP should also be a matter of concern as a mammalian health risk.

NADPH oxidase 5 activation; a novel approach to human sperm cryoinjury

Sperm cryopreservation leads to various structural and functional damages, some of which induce by oxidative stress. The reactive oxygen species (ROS) generates by mitochondria and membrane NADPH oxidases (NOXs). Among the NOXs, only NOX5 has been identified in the cell membrane of human sperm. This study was designed to clarify the possible role of NOX5 on sperm cryoinjury. Forty human semen samples were washed and randomly divided into fresh and cryopreserved groups. Each group was divided into 4 subgroups containing Ham's F10 (control), 0.1% DMSO (vehicle), 100 nM of PMA (phorbol 12-myristate 13-acetate) and 1 µM of DPI (diphenyleneiodonium), as NOX5 activator and inhibitor. The samples of cryopreserved groups were preserved in liquid nitrogen for 1 month. The sperm kinematics, membrane integrity, ROS production, apoptosis rate, mitochondrial membrane potential (MMP), intracellular ATP and calcium concentration [Ca²⁺]_i were evaluated. The percent of sperm with intact membrane and motile sperm reduced significantly after thawing (p ≤ 0.01). The ROS production (p ≤ 0.01) and the apoptotic rate increased, MMP dissipated, and the percentage of live cells with high [Ca²⁺]_i decreased significantly in the cryopreserved control group relative to the fresh control group. DPI, in contrast to PMA, improved sperm progressive motility (p ≤ 0.01), membrane integrity in fresh and cryopreserved groups and reduced the ROS amount in cryopreserved group (p ≤ 0.01). Apoptotic rate, [Ca²⁺]_i, ATP, and MMP did not change with DPI and PMA in cryopreserved groups. We conclude that NOX5 activity in fresh sperm is low, and it increases during cryopreservation. NOX5 inhibition improves the cryopreserved sperm quality.

The effect of sperm miR-34c on human embryonic development kinetics and clinical outcomes

AIMS

We aimed to investigate the effect of sperm miR-34c on early human embryonic development kinetics and clinical outcomes of in vitro fertilization (IVF) patients.

MATERIALS AND METHODS

After oocyte insemination, residual sperm specimens were collected from 58 patients undergoing IVF. miR-34c expression levels in sperm, oocytes, zygotes, and embryos/blastocysts were detected with qRT-PCR, and embryonic development kinetics were observed using time-lapse technology. To confirm the role of miR-34c in regulation of early embryonic development, miR-34c siRNA was injected into zygotes obtained from in vitro-matured oocytes. A ROC curve was used to determine the cutoff value. Comparisons of embryonic development kinetics and clinical outcomes were performed according to the cutoff value.

KEY FINDINGS

The miR-34c expression level was highest in 3PN zygotes, but was not expressed in human oocytes. In the miR-34c siRNA group, embryonic development kinetic parameters t2, t3, t4, and t5 were significantly prolonged, but the cleavage rate and high-quality embryo rate were lower than in the control group. The levels of sperm miR-34c were negatively correlated with t5 and positively correlated with rates of blastocyst formation, high-quality blastocysts, and pregnancy. The miR-34c levels and the blastocyst formation rate were higher in the pregnancy group (p < 0.05). Logistic regression analysis showed that sperm miR-34c level was significantly correlated with pregnancy (OR: 5.056, 95% CI: 1.560-16.384; p = 0.007).

SIGNIFICANCE

The sperm miR-34c expression level is associated with embryonic development kinetics and clinical outcomes. Thus, miR-34c expression is beneficial to embryonic development and may be used as an indicator of IVF outcomes.

Sperm cryostorage in a dry tank: An accurate alternative

This prospective study aimed to determine the effects of dry nitrogen cryostorage on human sperm characteristics in comparison with liquid nitrogen cryostorage. For this purpose, 42 men undergoing routine semen analysis (21 normozoospermia and 21 with altered semen parameters) were analyzed. After slow freezing, half of the straws of each sample were randomly stored in liquid and dry tanks, at the top and bottom levels of the latter. After 6 months storage, thawed samples were treated by density gradient centrifugation and sperm characteristics were compared. There was no difference in sperm progressive motility (15.1% ± 14.2% vs. 15.1% ± 12.7%; p = 0.76), sperm vitality (25.5% ± 17.7% vs. 26.2% ± 19%; p = 0.71), percentages of acrosome-reacted spermatozoa (38% ± 8.5% vs. 38.5% ± 7.4%; p = 0.53) and DNA fragmentation spermatozoa (27.3% ± 12.4% vs. 28.5% ± 12.9%, p = 0.47) after cryostorage in the dry or the liquid nitrogen tank. Moreover, we did not observe differences between either cryostorage system for normal and altered sperm samples. This lack of difference was also observed whatever the floor level of cryostorage in the dry tank. The temperature measurement of the dry tank showed a stable temperature at -194 °C throughout storage whatever the storage floor level, guaranteeing the stability of the low temperatures suitable for human sperm storage. Because of its greater safety, dry storage without contact with the liquid phase should be preferred and can be a useful alternative for the cryostorage of human sperm samples.

Knockout serum replacement is an efficient serum substitute for cryopreservation of human spermatozoa

The freeze-thaw procedure causes irreversible structural and functional changes in human spermatozoa. In order to decrease the detrimental effects of cryopreservation and improve the quality of post-thawed spermatozoa, the constituents of the freezing solution attracted considerable attention. In this study, for the first time, we evaluated the efficacy of knockout serum replacement (KSR) as a substitute for human serum albumin (HSA) for cryopreservation of human spermatozoa. Twenty semen samples were collected from normozoospermic men and divided them into five equal groups. One of the aliquots was diluted with glycerol-based medium as a control group (CON). The other four aliquots were diluted with the sucrose solution containing 5% HSA (H5), 10% HSA (H10), 5% KSR (K5), and 10% KSR (K10). The diluted samples were frozen and preserved in liquid nitrogen. Post thawed sperm parameters including motion characteristics, viability, membrane integrity, mitochondrial activity, acrosome integrity and DNA intactness in all of the sucrose-based groups were comparable with glycerol-based medium. The replacement of HSA by 10% KSR in the freezing medium resulted in significantly higher post-thawed viability, acrosome integrity and DNA intactness compared with other sucrose-based groups. In conclusion, the addition of 10% KSR to the sucrose-based freezing solution improves the quality of post-thawed human spermatozoa and may have potential to develop chemically defined freezing medium.

Impact of time between repeated sperm freezing cycles on sperm quality

Refreezing of sperm samples would provide the possibility of performing more cycles of fertility treatments. Although the effect of repeated cycles of freezing on sperm quality was studied, the effect of the length of the time interval between each freeze-thaw cycle has not been reported. Hence, we assessed the effect of incubation time on the sperm quality of thawed sperm after repeated freezing. One-hundred samples of potential sperm donations with normal sperm quality were evaluated. The fresh semen samples were analyzed and cryopreserved in liquid nitrogen until use. After thawing, the samples were divided randomly to two groups and reanalyzed for motility, vitality, and DNA fragmentation. They were incubated at room temperature and reanalyzed after either 90 min (group A) or 180 min (group B) of incubation, and once again after a repeated cycle of freezing and thawing. Our results showed that the sperm parameters of fresh samples of both groups were similar. After one freeze-thaw cycle, both groups still had comparable values. At the end of their respective incubation time periods, however, there was a significant difference in the mean values of the assessed parameters between the two groups (p < 0.01). An additional freeze-thaw cycle further exacerbated those differences, with group B undergoing an even more substantial decline (p < 0.001). Our data suggest that thawed human spermatozoa sustain a significant decline in sperm parameters in association with longer incubation time, which is further exacerbated by an additional freeze-thaw cycle.

Carica papaya seed extract slows human sperm

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional healers use Carica papaya seeds as a remedy for diseases and as a contraceptive for men and abortion in women.

MATERIAL AND METHODS

Semen samples from 35 healthy men were allowed to liquefy and subsequently incubated for 60 min in Human Tubular Fluid medium containing 1% bovine serum albumin with aqueous C. papaya seed extract at concentrations of zero, 0.025, 0.25, 2.5, 25, 250 and 2500 μg/ml. Afterwards, sperm were washed and used for assessment of capacitation and acrosome reaction, DNA fragmentation, vitality, motility, reactive oxygen species (ROS) and mitochondrial membrane potential (MMP).

RESULTS

The extract showed no effects on straight-line velocity, linearity, straightness, beat-cross frequency and the percentage of capacitated, acrosome-reacted sperm. In contrast, vitality, total motility, progressive motility, curvilinear velocity, average-path velocity and the percentages of hyper-activated, ROS-positive and MMP-intact sperm decreased significantly (P < 0.05), while the percentage of DNA-fragmented sperm increased (P < 0.05).

CONCLUSIONS

Our data show that aqueous C. papaya seed extract significantly and negatively affects sperm motility parameters crucial for fertility; and thus, poses as a likely candidate for male contraception.

Does supplementation of sperm freezing/thawing media with Ceratonia siliqua improve detrimental effect of cryopreservation on sperm parameters and chromatin quality in normozoospermic specimens?

Human sperm banking is an important procedure in the assisted reproductive technique centers. It entails sperm damage. The aim of this study was to investigate beneficial effect of Ceratonia siliqua (C. siliqua) supplement in freezing/thawing media on post thaw sperm parameters and sperm chromatin quality in normozoospermic samples. Forty normozoospermic specimens were included in this prospective study. Each sample was divided into ten groups. In groups one to five, 0 (as control group) 5, 10, 20 and 30 µg/ml C. siliqua were added to freezing medium and in groups six to ten, similar concentration of C. siliqua were added to thawing medium for 30 min incubation. Sperm concentration, progressive motility, normal morphology, viability, aniline blue (AB), toluidine blue (TB) and sperm chromatin dispersion (SCD) staining tests were evaluated before vitrification and after thawing. The results showed that 10 and 20 µg/ml supplementation of C. siliqua in freezing/thawing media significantly increased progressive motility, normal morphology and viability of sperm (p < 0.05) as well as decreased AB, TB and SCD (p < 0.05). Also, 20 µg/ml had significantly higher improvement compared to 10 µg/ml C. siliqua (p < 0.05). The present study showed that C. siliqua supplemented freezing/thawing media can improve sperm quality of normozoospermic samples after freezing/thawing.

In the human sperm nucleus, nucleosomes form spatially restricted domains consistent with programmed nucleosome positioning

In human sperm, a fraction of its chromatin retains nucleosomes that are positioned on specific sequences containing genes and regulatory units essential for embryonic development. This nucleosome positioning (NP) feature provides an inherited epigenetic mark for sperm. However, it is not known whether there is a structural constraint for these nucleosomes and, if so, how they are localized in a three-dimensional (3D) context of the sperm nucleus. In this study, we examine the 3D organization of sperm chromatin and specifically determine its 3D localization of nucleosomes using structured illumination microscopy. A fraction of the sperm chromatin form nucleosome domains (NDs), visible as microscopic puncta ranging from 40 μm to 700 μm in diameter, and these NDs are precisely localized in the post acrosome region (PAR), outside the sperm's core chromatin. Further, NDs exist mainly in sperm from fertile men in a pilot survey with a small sample size. Together, this study uncovers a new spatially-restricted sub-nuclear structure containing NDs that are consistent with NPs of the sperm, which might represent a novel mark for healthy sperm in human.

Differential motility parameters and identification of proteomic profiles of human sperm cryopreserved with cryostraw and cryovial

Background

Although sperm cryopreservation has been widely used in human reproductive medicine as an integral infertility management in infertility clinics and for banking sperm in sperm banks, the freezing/thawing protocols are not optimal. The freezing and thawing processes result in changes at both structural and molecular levels, some even detrimental, in human sperm when compared with fresh sperm. The change of sperm proteins after cryopreservation may play negative roles for fertilization and early embryo development. Conventionally, cryostraws (CS) and cryovials (CV) are the most widely used cryopreservation carriers (CPCs) for human sperm cryopreservation accompanied with the use of egg yolk free commercial media. However, the influence of cryopreservation on the proteomic profile of human sperm preserved with the two CPCs is unknown. Therefore the purpose of the present study was to compare the frozen-thawed motility, investigate the proteomic profile of human sperm cryopreserved with the two types of CPCs, and identify the susceptible proteins that play key roles for sperm function and fertility.

Methods

The present study compared the cryosurvival of human sperm frozen with the two different CPCs and identified the sperm proteomic changes by using the isobaric tags for relative and absolute quantification labeling technique coupled with 2D LC–MS/MS analysis after freezing and thawing.

Results

Our results indicated that sperm cryopreserved with CV showed higher values for percentage of motile sperm and forward activity rate than those with CS. Compared to fresh sperm, 434 and 432 proteins were differentially identified in human sperm cryopreserved with CS and CV, respectively.

Conclusion

The proteomic profiles of human sperm are greatly affected by cryopreservation with either type of CPC. GO analysis revealed that most of the differentially identified sperm proteins enriched in the extracellular membrane-bounded organelles, cytoplasm and cytosol. In addition, 106 susceptible proteins having known identities related to sperm functions were identified. In general, cryovial seems to be the preferred CPC for human sperm cryopreservation based on the post-thaw motility parameters and the effect on sperm proteomic profiles. These results are beneficial for the insight into the understanding of the cryoinjury mechanism of sperm and the development of human sperm cryopreservation strategies.

Electronic supplementary material

The online version of this article (10.1186/s12014-019-9244-2) contains supplementary material, which is available to authorized users.

Preclinical evaluation of a new cryopreservation container for a limited number of human spermatozoa

The aim of this study was to develop a new container for cryopreservation of a limited number of spermatozoa. To evaluate the efficacy and safety of this new container, we performed preclinical evaluations using human sperm or mouse oocytes and sperm. First, using human sperm that was frozen and then thawed, we demonstrated that the sperm recovery rate using the new container was 96.7% (58/60), which was significantly higher (P < 0.05) than the recovery rate of 21.2% (11/52) when using the Cryotop^®. Sperm motility rates were 19.2% (10/52) using the Cryotop^® and 35.0% (21/60) using the new container. Second, murine epididymal spermatozoa were divided into three groups: fresh spermatozoa, spermatozoa frozen using a straw, and spermatozoa frozen using the new container. Sperm motility, sperm membrane and DNA integrity, in vitro development of fertilized eggs, and offspring development after embryo transfer were assessed. The motility of freeze-thawed sperm was lower in spermatozoa that were frozen using the new container than in fresh spermatozoa or those that were frozen using a straw. After intracytoplasmic sperm injection, the survival rate was 96.7% (145/150), the 2-cell development rate was 90.3% (131/145), and the blastocyst development rate was 77.2% (112/145), when using the new container. There were no differences in the sperm membrane, DNA integrity, or in the embryo development rates to the blastocyst stage among the different frozen groups. Six offspring were derived from spermatozoa freeze-thawed in the new container, and they developed normally. Thus, the new container allows easy handling of a small number of sperms and minimizes sperm loss during cryopreservation.

Cryopreservation of human spermatozoa by vitrification versus conventional rapid freezing: Effects on motility, viability, morphology and cellular defects

OBJECTIVES

Sperm cryopreservation has great potential for male infertility treatment as used in assisted reproduction technology (ART). There are a variety of cryopreservation methods in order to preserve sperm in a long term. Although conventional freezing and vitrification now are used widely, they have damage on sperm parameters as well as sperm DNA integrity. It is necessary to answer which method is better and appropriate for sperm cryopreservation. The aim of this study was to compare the effect of conventional freezing and vitrification regarding to motility, vitality and morphology of sperm found in washed and unwashed samples.

STUDY DESIGN

One hundred and five human fresh semen samples were divided into washed and unwashed halves using density-gradient centrifugation. Each group then was split into two aliquots: one cryopreserved by conventional freezing and the other by vitrification, using SpermFreeze Solution™ (Vitrolife, Västra Frölunda, Sweden) containing glycerol as a cryoprotectant. The sperm parameters were analyzed and compared between six groups: washed fresh (FW), unwashed fresh (FU), washed conventional freezing (CfW), unwashed conventional freezing (CfU), washed vitrification (VitW) and unwashed vitrification (VitU) samples.

RESULTS

Sperm progressive motility, vitality and normal morphology significantly decreased, together with an appreciable increase in sperm head, midpiece and tail defects when comparing to the fresh sperm parameters after thawing in all groups. In conventional freezing method groups, progressive motility and vitality were substantially higher than that in vitrification method groups. However, vitrification gave better results in normal morphology rates. Additionally, sperm head, midpiece and tail defects were significant lower in two vitrification groups in comparison with conventional freezing groups. Interestingly, washed groups had better sperm parameters than unwashed groups so that washing process before frozen seemed to improve sperm parameters.

CONCLUSION

Conventional freezing method resulted in better motility, viability in both washed/unwashed groups. On the contrary, spermatozoa undergoing vitrification were healthier regarding morphology with less defects than conventional freezing. Sperm washing before frozen was a beneficial preparation to sperm cryopreservation.

Increased cryo-survival rate in ejaculated human sperm from infertile men following pre-freeze in vitro myo-inositol supplementation

Objective

To investigate the effects of in vitro myo-inositol (Myo-Ins) supplementation of cryopreserved human semen on the cryo-survival rate (CSR).

Methods

Semen samples were obtained from 41 infertile men. Following routine semen analysis, each sample was divided into two equal aliquots (0.5 mL each). One aliquot was treated with 1 mg of Myo-Ins dissolved in 10 µL of sperm preparation medium. The second aliquot was treated with 10 µL of the same medium (control). Both aliquots were incubated for 20 minutes prior to freezing to slow the freezing process. The frozen samples were examined for post-thaw percentages of total motility (TM), progressive motility (PM), and the CSR, defined as the percentage of post-thaw TM divided by the percentage of pre-freeze TM and multiplied in 100. The results were expressed as median and interquartile range (25th and 75th percentiles).

Results

The pre-freeze TM (50% [30%–50%]) and PM (35% [20%–35%]) were significantly higher than the post-thaw TM and PM in the Myo-Ins group (15% [10%–35%] and 10% [5%–20%]; p<0.001 and p<0.001, respectively) and the control group (10% [6%–30%] and 5% [3%–15%]; p<0.001 and p<0.001, respectively). The CSR of the 41 semen aliquots supplemented with Myo-Ins (40% [25%–70%]) was significantly higher than that of the control samples (30% [13%–58%], p=0.041). The CSR of the 26 abnormal semen samples that were supplemented with Myo-Ins (38% [20%–50%]) was significantly higher than that of the control samples (23% [12%–30%], p=0.031).

Conclusion

In vitro Myo-Ins supplementation of ejaculated human sperm from infertile men resulted in a significant increase in the CSR in samples with abnormal pre-freeze sperm parameters.

Vitamin C attenuates negative effects of vitrification on sperm parameters, chromatin quality, apoptosis and acrosome reaction in neat and prepared normozoospermic samples

OBJECTIVE

Aim of this study was to evaluate the effects of vitamin C on sperm parameters, sperm chromatin quality and apoptosis resulted of vitrification in neat semen and prepared spermatozoa of normozoospermic samples.

MATERIAL AND METHODS

Forty semen samples from normozoospermic men were included in this prospective study. Each sample was divided into five groups. Group I: control or fresh semen, group II: semen prepared by swim-up method and then vitrified, group III: neat semen was vitrified, group IV: vitamin C (600 μM) was added to prepared spermatozoa and then vitrified and group V: vitamin C (600 μM) was added to neat semen and then vitrified. After warming, sperm analysis was done accordingly. For evaluating the sperm chromatin/DNA integrity status and acrosome reaction, we used toluidine blue (TB), acridine orange (AO), terminal transferase mediated deoxyuridine triphosphate biotin end labeling (TUNEL) and double staining tests.

RESULTS

All of the sperm parameters (count, motility, morphology and viability) had significant differences (P < 0.05) between different groups, especially in group IV. Data showed sperm chromatin damages and acrosome reaction abnormality increased resulted of vitrification, but, in the groups that added vitamin C (IV, V) rate of damages was decreased and this was notable in the group IV.

CONCLUSION

Vitamin C can attenuate the detrimental effects of vitrification on sperm parameters, chromatin quality and rate of apoptosis in both neat semen and prepared spermatozoa of normozoospermic samples.

Comparative analysis of human sperm glycocalyx from different freezability ejaculates by lectin microarray and identification of ABA as sperm freezability biomarker

Background

Semen cryopreservation has been widely applied in assisted reproductive technologies and sperm bank, but it causes considerable impairments on sperm quality. It is necessary to find an evaluation indicator for determining the sperm-freezing tolerance.

Methods

The glycocalyx of good freezability ejaculates was compared with poor freezability ejaculates by lectin microarray. The significant different lectins were validated by flow cytometry (FACS). To analyze the relationship between the potential biomarker and the tolerance of sperm to cryopreservation, 60 samples with different recovery rates were collected and detected the lectin-binding intensity by FACS. The receiver operating characteristic (ROC) curve was analyzed to test the capability of the lectin as a potential biomarker for detecting the sperm freezablility.

Results

ABA and DSL were found to develop significant differences between them. Further validation showed that ABA was significantly negative correlated with the sperm recovery rates (r = - 0.618, P < 0.000) and could be a potential biomarker for predicting sperm freezability (AUC = 0.733 ± 0.067, 95% CI 0.601 - 0.865, P < 0.01).

Conclusion

ABA could be a potential biomarker for predicting sperm freezability. It will help to reduce sperm-freezing recovery tests and improve the efficiency of cryopreservation in human sperm bank.

Human sperm cryopreservation in cancer patients: Links with deprivation and mortality

Evidence is mounting for a relationship between human semen quality and environmental/lifestyle/socioeconomic factors including long term health outcomes such as mortality. The relationship between pre-freeze and post-thaw semen quality in cancer patients and these factors are unknown. Frozen semen from 217 cancer patients was thawed and analysed using a validated CASA method. Post-thaw quality was matched and compared with WHO semen analysis performed prior to storage. The English Indices of Deprivation 2010 were matched with patients and then examined for relationships with pre-freeze and post-thaw semen quality. There is a relationship between semen quality and deprivation in cancer patients. Compared with pre-freeze semen quality, post-thaw semen quality has a stronger relationship with deprivation. Sperm cryopreservation may have potential as a systemic health diagnostic test and is predictive of cancer patient mortality.

Expression and localization of tubulin cofactors TBCD and TBCE in human gametes

The tubulin cofactors TBCD and TBCE play an essential role in regulation of the microtubule dynamics in a wide variety of somatic cells, but little information is known about the expression of these cofactors in human sperm and oocytes. In this study, we focused on the investigation of the presence of, and the differential distribution of, the tubulin cofactors TBCD and TBCE in human sperm and during human oocyte maturation. We performed expression assays for TBCD and TBCE by reverse transcription-polymerase chain reaction (RT-PCR), western blot and immunofluorescence and verified the presence of both cofactors in human gametes. TBCD and TBCE were located mainly in the middle region and in the tail of the sperm while in the oocyte the localization was cytosolic. The mRNA of both tubulin cofactors were present in the human oocytes but not in sperm cells. This finding gives a first insight into where TBCD and TBCE could carry out their function in the continuous changes that the cytoskeleton experiences during gametogenesis and also prior to fertilization.

Sodium-Hydrogen-Exchanger expression in human sperm and its relationship with semen parameters

PURPOSE

Sperm-specific sodium-hydrogen exchanger (sNHE) is essential to maintain sperm normal function in mice; however, its role in human sperm has not been clarified to date. The aim of this study is to investigate the expression pattern of sNHE in human spermatozoa and its relationship with sperm functional parameters.

METHOD

Semen samples from 68 asthenozoospermic and 61 normozoospermic men were analyzed for sperm concentration, motility, and acrosome reaction, and high motile spermatozoa were collected by swim-up method. The expression of sNHE in spermatozoa was detected by Western blot and immunofluorescence staining. The relationship between sNHE expression and sperm parameters was assessed.

RESULTS

We identified sNHE is mainly localized to the principal piece of the human sperm tail. The expression of sNHE was positively correlated with sperm concentration, total number, and progressive motility. Moreover, sNHE expression was upregulated in swim-up sperm and associated with most of sperm motility parameters including straight line velocity and curvilinear velocity. Our results also showed that sNHE expression is decreased in sperm from patients with asthenozoospermia compared with that from normal controls. However, no correlation was found between sNHE expression and acrosome reaction in spermatozoa.

CONCLUSIONS

The expression pattern of sNHE suggested that this protein may be involved in the regulation of sperm motility, and aberration of its expression in sperm may contribute to the pathogenesis of asthenozoospermia.

Progesterone requires heat shock protein 90 (HSP90) in human sperm to regulate motility and acrosome reaction

PURPOSE

The aims of this paper were to study whether heat shock protein 90 (HSP90) is a regulator of sperm functions and to determine its association with oligoasthenozoospermia.

METHODS

The levels of HSP90 in sperm lysates were measured by ELISA. Localization of HSP90 and its isoforms was evaluated by immunofluorescence. Sperm motility and kinetics were assessed by computer-assisted sperm analysis. Acrosome reaction was determined by lectin staining.

RESULTS

The levels of HSP90 were lower in oligoasthenozoospermic men and correlated positively with the number of motile spermatozoa. In capacitated human spermatozoa, HSP90α was mostly found in residual nuclear envelope, and the HSP90β isoform was higher in the flagella. Inhibition of HSP90 by geldanamycin or 17-AAG did not affect basal motility, but suppressed progesterone-mediated forward progressive motility, hyperactivation and acrosome reaction. Progesterone treatment dephosphorylated both HSP90α and HSP90β at Ser/Thr-Pro residues, but not Tyr residues.

CONCLUSION

HSP90 levels are downregulated in oligoasthenozoospermia, and its functional inhibition attenuates progesterone-mediated sperm motility and acrosome reaction.

Oxidative stress markers: Can they be used to evaluate human sperm quality?

OBJECTIVE

To study the effects of an acute lifestyle change in human semen oxidative stress (OS) by applying seminal parameters and OS markers and to study the feasibility of mid-infrared spectroscopy with Fourier transform infrared spectroscopy (FT-IR) as a complementary tool to evaluate the effects of OS on human sperm samples.

MATERIAL AND METHODS

Sperm samples were collected from healthy male students (n=8) who voluntarily submitted themselves to acute lifestyle changes during academic festivities. The samples were obtained before and after the academic festivities and were compared by basic semen analyses and OS markers, namely with thiobarbituric acid reactive species (TBARS) and total thiol (SH) groups by spectrophotometric assays and carbonyl (CO) groups by slot blot. The samples were also submitted for spectroscopic analysis to evaluate the feasibility of FT-IR coupled with multivariate analysis to calibrate OS biomarkers. Statistical analysis was performed applying paired Wilcoxon tests.

RESULTS

Acute lifestyle alterations during academic week festivities were associated with a significant decrease in the percentage of normal spermatozoa in the ejaculate (p=0.011) and a decrease in sperm concentration and in semen volume. Regarding OS, acute lifestyle changes promoted a significant increment of TBARS (p=0.018) and an increasing trend in the SH group. With FT-IR and multivariate analysis, it was possible to develop calibration models to the following protein OS biomarkers: SH groups and CO.

CONCLUSIONS

Acute lifestyle changes during academic festivities have negative effects on sperm quality, in both conventional seminal parameters and OS markers. The evaluation of OS biomarkers and FT-IR could improve andrology diagnosis and therapeutic follow-up.

An efficient method for automatic morphological abnormality detection from human sperm images

BACKGROUND AND OBJECTIVE

Sperm morphology analysis (SMA) is an important factor in the diagnosis of human male infertility. This study presents an automatic algorithm for sperm morphology analysis (to detect malformation) using images of human sperm cells.

METHODS

The SMA method was used to detect and analyze different parts of the human sperm. First of all, SMA removes the image noises and enhances the contrast of the image to a great extent. Then it recognizes the different parts of sperm (e.g., head, tail) and analyzes the size and shape of each part. Finally, the algorithm classifies each sperm as normal or abnormal. Malformations in the head, midpiece, and tail of a sperm, can be detected by the SMA method. In contrast to other similar methods, the SMA method can work with low resolution and non-stained images. Furthermore, an image collection created for the SMA, has also been described in this study. This benchmark consists of 1457 sperm images from 235 patients, and is known as human sperm morphology analysis dataset (HSMA-DS).

RESULTS

The proposed algorithm was tested on HSMA-DS. The experimental results show the high ability of SMA to detect morphological deformities from sperm images. In this study, the SMA algorithm produced above 90% accuracy in sperm abnormality detection task. Another advantage of the proposed method is its low computation time (that is, less than 9s), as such, the expert can quickly decide to choose the analyzed sperm or select another one.

CONCLUSIONS

Automatic and fast analysis of human sperm morphology can be useful during intracytoplasmic sperm injection for helping embryologists to select the best sperm in real time.

Functional distribution of synapsin I in human sperm

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Synapsin I was localized in the human sperm equatorial segment.

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Presence of synapsin I was confirmed by dot and Western blotting techniques.

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Treatment of sperm with anti-synapsin antibodies significantly decreased motility.

Proteins known to function during cell–cell communication and exocytosis in neurons and other secretory cells have recently been reported in human sperm. Synapsins are a group of proteins that have been very well characterized in neurons, but little is known about synapsin function in other cell types. Based upon previous findings and the known function of synapsin, we tested the hypothesis that synapsin I was present in human sperm. Washed, capacitated, and acrosome induced sperm preparations were used to evaluate the functional distribution of synapsin I using immunocytochemistry. Protein extracts from mouse brain, mouse testis/epididymis, and human semen were used for protein blotting techniques. Immunolocalization revealed synapsin I was enriched in the sperm equatorial segment. Protein extracts from mouse brain, mouse testis/epididymis, and human semen were positive for synapsin I using several different antibodies, and dot blot results were confirmed by Western blot analyses. Finally, treatment of capacitated and acrosome reaction induced samples with anti-synapsin antibodies significantly reduced sperm motility. Localization of synapsin I in human sperm is a novel finding. The association of synapsin I with the sperm equatorial segment and effects on motility are suggestive of a role associated with capacitation and/or acrosome reaction, processes that render sperm capable of fertilizing an oocyte.

how on sexual function in male mice and its antioxidant protection of human sperm

ETHNOPHARMACOLOGICAL RELEVANCE

In recent years, the physiological aspects of human fertility have been seriously influenced by the interactions of genetic and environmental factors. Almost one in 20 males has been affected by male infertility, providing a great challenge and an opportunity to use natural compounds as alternatives to chemical drugs with comprehensive adverse effects. However, ample evidences are scanty to support the physiological mechanisms of natural compounds used to treat male infertility. In traditional Chinese medicine, Morinda officinalis F. C. How is widely used as a herb that invigorates the kidneys and supports yang, the original energy in the human body, to resist diseases and in treating male infertility. In this study, we evaluated whether bajijiasu isolated from the roots of M. officinalis F.C. How is a potential agent for the treatment of male infertility.

MATERIALS AND METHOD

In this study, both normal and kidney-yang-deficient mice were administered bajijiasu orally at different concentrations. To determine the pharmacological mechanism of bajijiasu, we observed the sexual behavior and genital organ coefficients, determined their serum hormone levels, analyzed their sperm quality parameters, and examined histopathological sections from them. We also used enzymatic assays to determine the effects of bajijiasu on superoxide dismutase, glutathione peroxidase, and malondialdehyde. Confocal micro-Raman spectroscopy was used to investigate the changes in the DNA of H2O2-damaged human sperm after treatment with bajijiasu in vitro.

RESULTS

Our results showed that bajijiasu enhanced the sexual behavior of both normal and kidney-yang-deficient mice. It also markedly increased the testosterone concentrations, reduced the levels of cortisol, improved the quality of the sperm, and counteracted the histopathological impairment induced by hydroxyurea in the kidney-yang-deficient mice. The enzymatic assay and Raman spectra showed that bajijiasu protects the DNA of sperm from damage by H2O2.

CONCLUSION

Bajijiasu is a potential androgen-like drug that modulates hormone levels to some extent without producing reproductive-organ lesions, enhances the sexual function of male mice, and protects the DNA of human sperm from H2O2 damage. Thus, bajijiasu is an active ingredient of M. officinalis F.C. How that improves the human reproductive capacity.

Nerve growth factor in human semen: Effect of nerve growth factor on the normozoospermic men during cryopreservation process

OBJECTIVES

Although routinely applied in assisted reproductive technology, human sperm cryopreservation is not a completely successful procedure. Adverse effects of cryopreservation on the fertilization capacity, motility, morphology, and viability of spermatozoa have been proven; cryopreservation has also shown a role in sperm DNA fragmentation and infertility. The post-thaw survival of spermatozoa improved after addition of supplementation of antioxidant molecules to freezing media. Nerve growth factor (NGF) as one of the prosurvival substances has gained great attention in recent years. The aim of this study was the usage of NGF as prosurvival factor after cryopreservation process of human semen samples to assess the motility and viability of sperm, nitric oxide (NO) concentration, and DNA fragmentation in normozoospermic men.

MATERIALS AND METHODS

Semen samples were collected from 25 normozoospermic men and were divided into fresh semen samples as control group, frozen-thawed semen samples without addition of exogenous NGF, and three groups of semen samples cryopreserved with addition of exogenous NGF (0.5, 1, and 5 ng/ml) in freezing medium. Viability was assessed by eosin-negrosin staining technique. Motility was evaluated with inverted microscope. NO concentration and apoptosis content were measured with flow cytometry.

RESULTS

Results showed that exogenous NGF at 0.5 ng/ml could significantly (P-value <0.05) influence viability, motility, nitric oxide, and DNA fragmentation content.

CONCLUSION

Exogenous NGF as cryoprotectant improved sperm viability and motility, increased intracellular NO concentration, and decreased apoptosis content in normal human spermatozoa.

Can Helicobacter pylori infection influence human reproduction?

Helicobacter pylori (H. pylori) infection could be associated with extra-digestive diseases. Here, we report the evidences concerning the decrease in reproductive potential occurring in individuals infected by H. pylori, especially by strains expressing CagA. This infection is more prevalent in individuals with fertility disorders. Infected women have anti-H. pylori antibodies in cervical mucus and follicular fluid that may decrease sperm motility and cross react immunologically with spermatozoa, conceivably hampering the oocyte/sperm fusion. Infection by CagA positive organisms enhances the risk of preeclampsia, which is a main cause of foetus death. These findings are supported by the results of experimental infections of pregnant mice, which may cause reabsorption of a high number of foetuses and alter the balance between Th1 and Th2 cell response. Infected men have decreased sperm motility, viability and numbers of normally shaped sperm and augmented systemic levels of inflammatory cytokines, such as tumor necrosis factor-α, which may damage spermatozoa. In countries where parasitic infestation is endemic, detrimental effects of infection upon spermatozoa may not occur, because the immune response to parasites could determine a switch from a predominant Th1 type to Th2 type lymphocytes, with production of anti-inflammatory cytokines. In conclusion, the evidences gathered until now should be taken into consideration for future studies aiming to explore the possible role of H. pylori infection on human reproduction.