Association between the seminal plasma proteome and sperm functional traits

Intraindividual variability of semen quality, proteome, and sncRNA profiles in a healthy cohort of young adults

BACKGROUND

Within-subject variability of semen parameters and molecular components of ejaculates in young men remains poorly understood.

OBJECTIVES

To investigate intraindividual variability (IIV) of semen parameters and molecular markers in repeated ejaculates from young men.

MATERIALS AND METHODS

Semen parameters were assessed in samples collected 6-8 days apart from 164 18-19-year old participants of the Russian Children's Study, a prospective cohort. Subsets of paired samples were used for label-free quantitation and targeted mass-spectrometry of proteins in seminal plasma (SP) and seminal extracellular vesicles (EVs), and for small non-coding RNA (sncRNA) profiling in EVs and spermatozoa using RNA-seq. The mean difference between two ejaculates, within-subject variation, intraclass correlation, and concordance correlation were used to assess IIV for all parameters. Low variability with high reproducibility and high reliability was considered if CVw < 15% and ICC > 0.90, respectively.

RESULTS

Analytical variability was low for all investigated parameters in technical replicates. IIV was assessed for basic semen parameters and proteins in SPs and EVs: 319 and 777 proteins, respectively, using untargeted analysis; 9 and 10 proteins using targeted quantification. We also described the IIV for sncRNA, including microRNA, piwi-interacting RNA, tRNA, and tRNA-derived small RNA (tsRNA) in EVs (409 sncRNA and 78 tsRNA) and in spermatozoa (265 sncRNA and 15 tsRNA). We identified 22 and 27 non-overlapping proteins in SP and EVs, respectively, and 46 and 9 sncRNA, including 5 and 0 tsRNA in seminal EVs and spermatozoa, respectively, with low variability. The fatty acid synthase (FAS) had the lowest IIV in both media in targeted protein quantification.

DISCUSSION

We identified a number of proteins and sncRNA with low variability among 111 proteins, 176 sncRNA, and 12 tsRNA which were previously suggested as biomarkers of male fertility and reproductive outcomes: lactotransferrin, cysteine-rich secretory protein 3, alpha-1-antichymotrypsin, epididymal sperm-binding protein 1, glutathione S-transferase Mu 3, alpha-1-acid glycoprotein 2, serum amyloid P-component, aminopeptidase N, neprilysin, FAS, and miR-10b-3p, miR-122-5p, miR-205-5p, miR-222-3p, miR-34c-5p, miR-509-3-5p, miR-888-5p, miR-892a, miR-363-3p, miR-941, miR-146a-5p, miR-744-5p.

CONCLUSION

These molecules have low IIV and may be promising candidate biomarkers of male fertility and reproductive health.

Insight into inflammation involvement in varicocele: A narrative review

BACKGROUND

Varicocele is one of the main causes of male infertility. Although the pathophysiology mechanism of varicocele is very well described and understood, there are some unanswered questions that remains unknown. Some studies have previously described the state of testicular inflammation and sperm in animal models, especially the mouse model, and the seminal plasma of men with varicocele, with or without changes in semen parameters.

METHODS OF STUDY

This review intended to verify the role of inflammatory mechanism in varicocele, using clinical studies as well as animal model studies on the effect of inflammation caused by varicocele on the function of testicular somatic and germ cells.

RESULTS

In-vivo studies confirmed whether anti-inflammatory molecules could treat the semen of men with varicocele and rats with varicocele. The use of different anti-inflammatory agents in mouse model studies provided a new perspective for future clinical studies to investigate the effect of concurrent treatment with surgery to improve surgical outcomes.

CONCLUSION

Similar to animal model studies, previously conducted clinical trials have demonstrated the effectiveness of anti-inflammatory therapy in varicocele patients. However, clinical trials using anti-inflammatory are needed to be conducted agents to evaluate different aspects of this therapeutical approach in varicocele patients.

Non-targeted proteomic analysis of Asian elephant (Elephas maximus) seminal plasma using an in-solution digestion technique and liquid chromatography tandem-mass spectrometry

Seminal plasma proteins have recently been reported to play a significant role as valuable materials for understanding male reproductive biology, identifying causes of fertility problems, and developing reproductive biomarkers. Proteomic analysis of seminal plasma holds promise in advancing the understanding of male Asian elephant reproductive biology. This study aims to explore seminal plasma proteins of Asian elephants and their probable functions to provide fundamental information about male reproduction in this species. The protein solution from pooled seminal plasma from 10 bulls (a total of 33 ejaculates) was digested into peptides and identified using LC-MS/MS. Out of 986 proteins, 597 were mapped and matched with 58 species in UniProt databases, including Elephas maximus. These mapped proteins were mostly involved in binding function, catalytic activity, cellular process, and metabolic process. Only 29 mapped proteins were recognized to be related in reproductive process, mainly associated in spermatogenesis and sperm capacitation. Additionally, several seminal plasma proteins related to fertility or semen quality in other mammals were also found in Asian elephant semen, such as keratin type I, aldose reductase, thrombospondon-1, fibronectin 1, platelet-activating factor acetyl hydrolase, mannosidase, and semenogelin-2. This discovery clearly reveals the beneficial protein profile in seminal plasma of the Asian elephant and serves as a crucial step in investigating infertility and poor semen quality in this valuable species.

Separating the chaff from the wheat: antibody-based removal of DNA-fragmented sperm

STUDY QUESTION

Is it possible to remove sperm with damaged DNA from a semen sample?

SUMMARY ANSWER

By using immunomagnetic cell sorting that targets the sperm head-bound epididymal sperm-binding protein 1 (ELSPBP1), it was possible to produce an ELSPBP1(-) sperm fraction characterized by consistently lower levels of sperm DNA fragmentation (SDF).

WHAT IS KNOWN ALREADY

In bovines, ELSPBP1 is bound to dead spermatozoa. Human ejaculates with high SDF have increased detected levels of sperm ELSPBP1 when compared to ejaculates with low native SDF.

STUDY DESIGN, SIZE, DURATION

We recruited 267 patients who were referred to the clinic for conjugal infertility. After applying exclusion criteria, such as fever within 90 days of the study, history of systemic diseases, alterations or surgical interventions to the genital tract and use of cigarette or drugs, a total of 133 patients were included. A total of 52 samples were used for the evaluation of sperm ELSPBP1 levels (Sub-study 1), 41 samples for determination of ELSPBP1 location in human sperm (Sub-study 2), and 40 samples for immunomagnetic cell sorting targeting ELSPBP1, to produce ELSPBP1(-) (without ELSPBP1) and ELSPBP1(+) (with ELSPBP1) fractions (Sub-study 3). Samples were collected between July 2016 and September 2019.

PARTICIPANTS/MATERIALS, SETTING, METHODS

In Sub-study 1, sperm ELSPBP1 levels were assessed by western blotting. For Sub-study 2, ELSPBP1 was localized in sperm by immunocytochemistry. Finally, for Sub-study 3, sperm were selected based on incubation of semen samples with antibody-coated magnetic microspheres targeting ELSPBP1. Two fractions were produced (with or without ELSPBP1), and these sub-populations were submitted to an alkaline Comet assay for determination of SDF.

MAIN RESULTS AND THE ROLE OF CHANCE

Men with high SDF presented higher sperm ELSPBP1 levels when compared to the control group (low SDF), while no difference between groups was observed in seminal plasma. ELSPBP1 was located in the head region of human sperm. The ELSPBP1(+) fractions presented high and variable levels of SDF, while their paired ELSPBP(-) fractions presented consistently low SDF.

LIMITATIONS, REASONS FOR CAUTION

This work did not validate the levels of ELSPBP1 in other functional alterations of sperm, such as acrosome integrity or mitochondrial activity. Moreover, this is still a pre-clinical study, intended to demonstrate proof-of-concept that ELSPBP1 selects sperm with low DNA fragmentation; further investigation is warranted to demonstrate safety for use in ART. Sperm fractions were not assessed for sperm vitality. A clinical trial is still necessary for these findings to be extrapolated to outcomes in ART.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings demonstrate that ELSPBP1 is associated with sperm with higher levels of DNA fragmentation. The finding that the sperm membrane can reflect alterations in DNA integrity could give rise to a novel molecular method for sperm preparation prior to use of assisted reproductive procedures. Moreover, the detection of sperm-bound ELSPBP1 could serve as an indirect method for the determination of DNA fragmentation.

STUDY FUNDING/COMPETING INTEREST(S)

L.B.B. was a recipient of a Ph.D. scholarship from the Sao Paulo Research Foundation-FAPESP (process number 2016/05487-3). R.P.B. is a recipient of a Scientific Productivity scholarship from the Brazilian National Council for Scientific and Technological Development-CNPq (process number 306705/2017-6). The authors have no conflict of interest to disclose.

TRIAL REGISTRATION NUMBER

N/A.

Supplementation of Alpha-lipoic acid-loaded nanoliposomes in semen extender improves freezability of buffalo spermatozoa

This research was designed to explore the protective effect of alpha-lipoic acid-loaded nanoliposomes (ALAN) during cryopreservation of buffalo sperm. Buffalo semen was cryopreserved in a tris-citrate egg yolk extender without any supplement (ALAN0, control group) or with ALAN at levels of 25, 50, 75 or 150 µg (ALAN25, ALAN50, ALAN75 and ALAN150, respectively). The ALAN had a size of 171.80 nm and a negative zeta potential (- 43.40 mV). The progressive motility, vitality and membrane integrity significantly improved in all ALAN groups (except ALAN25 for membrane integrity). ALAN150 group exhibited the best values of progressive sperm motility, vitality and membrane integrity after thawing at 37 °C for 30 s or incubated for 2 h at 37 °C and 5% CO₂ compared with those in other groups. Both ALAN75 and ALAN150 groups significantly improved the TAC, GR and catalase, while lipid peroxidation and early apoptotic spermatozoa significantly decreased in ALAN150 group followed by ALAN75 group. Collectively, the adding ALAN to buffalo semen freezing extender plays a substantial shielding function against cryodamage by preserving the sperm functional parameters.

A systematic review identifying fertility biomarkers in semen: a clinical approach through Omics to diagnose male infertility

OBJECTIVE

To identify the most robust molecular biomarkers in sperm and seminal plasma for the diagnosis of male infertility, and to evaluate their clinical use.

DESIGN

Systematic review.

SETTING

Not applicable.

PATIENT(S)

Accessible studies reporting well-defined (in)fertile populations and semen molecular biomarkers were included in this review.

INTERVENTION(S)

A systematic search of the literature published in MEDLINE-PubMed and EMBASE databases was performed, following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

MAIN OUTCOME MEASURE(S)

The primary outcome was the content, expression, or activity of molecular biomarkers in human semen samples. Only studies reporting a receiver-operating characteristic (ROC) analysis values were included.

RESULT(S)

Eighty-nine studies were included. Direct evaluation of sperm DNA damage has high potential as a diagnostic biomarker of fertility and assisted reproductive technology outcomes (area under the curve [AUCs] median = 0.67). Regarding strand break-associated chromatin modifications, γH2AX levels show good predictive value for the diagnosis of male infertility (AUCs median = 0.93). Some noncoding ribonucleic acid (RNA) exhibit excellent predictive values; miR-34c-5p in semen is the most well-characterized and robust transcriptomic biomarker (AUCs median = 0.78). While many proteins in semen show fair diagnostic value for sperm quality and fertilizing capacity, the levels of some, such as TEX101, in seminal plasma have an excellent diagnostic potential (AUCs median = 0.69). Although individual metabolites and metabolomic profiles in seminal plasma present good predictive value, the latter seem to be better than the former when inferring sperm quality and fertilizing capacity.

CONCLUSION(S)

The current review supports that some Omics (e.g., DNA structure and integrity, genomics and epigenomics, transcriptomics, metabolomics, and proteomics) could be considered relevant molecular biomarkers that may help identify infertility etiologies and fertilization prognosis with cost-effective, simple, and accurate diagnosis.

Proteomic insight of seminal plasma in spinal cord injured men submitted to oral probenecid treatment for improved motility

OBJECTIVE

To observe the seminal plasma proteomic composition in men with spinal cord injury orally treated with probenecid, in order to observe pathways associated with increased sperm motility.

STUDY DESIGN

Prospective study.

SETTING

Miami Project to Cure Paralysis - University of Miami/Miller School of Medicine.

PARTICIPANTS

Nine men with spinal cord injury, who agreed to participate in the study.

INTERVENTION

Oral treatment with probenecid - 500 mg per day for one week, then 500 mg twice daily [1000 mg total] per day for three weeks.

OUTCOME MEASURES

Semen analysis as per WHO 2010 guidelines, and seminal plasma proteomics analysis by LC-MS/MS.

RESULTS

In total, 783 proteins were identified, of which, 17 were decreased, while 6 were increased after treatment. The results suggest a new pathway that could be treated by the decrease of biglycan after probenecid treatment.

CONCLUSION

Oral treatment with probenecid is able to alter the seminal plasma proteome, in pathways that explain decreased innate immune response.

Deciphering metabolomic alterations in seminal plasma of crossbred (Bos taurus X Bos indicus) bulls through comparative deep metabolomic analysis

The incidence of sub-fertility is higher in crossbred bulls compared to zebu bulls. In the present study, we analysed the metabolomic profile of seminal plasma from crossbred and zebu bulls and uncovered differentially expressed metabolites between these two breeds. Using a high-throughput LC-MS/MS-based approach, we identified 990 and 1,002 metabolites in crossbred and zebu bull seminal plasma respectively. After excluding the exogenous metabolites, we found that 50 and 68 putative metabolites were unique to crossbred and zebu bull seminal plasma, respectively, whilst 87 metabolites were common to both. After data normalisation, 63 metabolites were found to be dysregulated between crossbred and zebu bull seminal plasma. Observed pathways included Linoleic acid metabolism (observed metabolite was phosphatidylcholine) in crossbred bull seminal plasma whereas inositol phosphate metabolism (observed metabolites were phosphatidylinositol-3,4,5-trisphosphate/inositol 1,3,4,5,6-pentakisphosphate/myo-inositol hexakisphosphate) was observed in zebu bull seminal plasma. Abundance of Tetradecanoyl-CoA was significantly higher, whilst abundance of Taurine was significantly lower in crossbred bull seminal plasma. In conclusion, the present study established the seminal plasma metabolomic profile in crossbred and zebu bulls and suggest that increased lipid peroxidation coupled with low concentrations of antioxidants in seminal plasma might be associated with high incidence of sub-fertility in crossbred bulls.

The characteristics of proteome and metabolome associated with contrasting sperm motility in goat seminal plasma

Sperm motility is an index tightly associated with male fertility. A close relationship between seminal plasma and sperm motility has been confirmed. This study was to assess the protein and metabolite profiles of seminal plasma obtained from adult goats with high or low sperm motility using the proteomic and metabolomic strategies. In total, 2098 proteins were found. 449 differentially abundant proteins (DAPs) were identified, and 175 DAPs were enriched in the high motility group. The obtained DAPs primarily exist in cytoplasma and extra-cellular portion. The Gene Ontology enrichment analysis demonstrated the main functional roles of these DAPs in regulating biological process, metabolic process of organic substances, cellular-metabolic process, primary-metabolic process, metabolic process of nitrogen compounds, etc. Additionally, the Kyoto-Encyclopedia of Genes and Genomes (KEGG) analysis revealed that these DAPs were primarily involved in phosphatidylinositol signaling system, salivary secretion, proteasome, apoptosis, mitophagy-animal, etc. Aided by the parallel reaction monitoring technology, the abundance changing pattern of 19 selected DAPs was consistent with that of the corresponding proteins obtained by TMT. A total of 4603 metabolites were identified in seminal plasma. 1857 differential metabolites were found between the high motility group and the low motility group, and 999 metabolites were up-regulated in the high motility group. The KEGG analysis demonstrated the primary involvement of the differential metabolites in metabolic and synthetic activities. In conclusion, we first established the proteome and metabolome databank of goat seminal plasma, detecting some proteins and metabolites which may affect sperm motility. This study will be valuable for understanding mechanisms leading to poor sperm motility.

Protein Identification of Spermatozoa and Seminal Plasma in Bottlenose Dolphin (Tursiops truncatus)

Proteins play an important role in many reproductive functions such as sperm maturation, sperm transit in the female genital tract or sperm-oocyte interaction. However, in general, little information concerning reproductive features is available in the case of aquatic animals. The present study aims to characterize the proteome of both spermatozoa and seminal plasma of bottlenose dolphins (Tursiops truncatus) as a model organism for cetaceans. Ejaculate samples were obtained from two trained dolphins housed in an aquarium. Spermatozoa and seminal plasma were analyzed by means of proteomic analyses using an LC-MS/MS, and a list with the gene symbols corresponding to each protein was submitted to the DAVID database. Of the 419 proteins identified in spermatozoa and 303 in seminal plasma, 111 proteins were shared by both. Furthermore, 70 proteins were identified as involved in reproductive processes, 39 in spermatozoa, and 31 in seminal plasma. The five most abundant proteins were also identified in these samples: AKAP3, ODF2, TUBB, GSTM3, ROPN1 for spermatozoa and CST11, LTF, ALB, HSP90B1, PIGR for seminal plasma. In conclusion, this study provides the first characterization of the proteome in cetacean sperm and seminal plasma, opening the way to future research into new biomarkers, the analysis of conservation capacity or possible additional applications in the field of assisted reproductive technologies.

Altered Gene Expression in the Testis of Infertile Patients with Nonobstructive Azoospermia

Background

The molecular mechanism of nonobstructive azoospermia (NOA) remains unclear. The aim of this study was to identify gene expression changes in NOA patients and to explore potential biomarkers and therapeutic targets.

Methods

The gene expression profiles of GSE45885 and GSE145467 were collected from the Gene Expression Omnibus (GEO) database, and the differences between NOA and normal spermatogenesis were analyzed. Enrichment analysis was performed to explore biological functions for common differentially expressed genes (DEGs) in GSE45885 and GSE145467. Coexpression analysis of DEGs in GSE45885 was performed, and two modules with the highest correlation with NOA were screened. Key genes were then screened from the intersection genes of the two modules and common DEGs and PPI network. The expression of key genes was validated by quantitative real-time polymerase chain reaction (qRT-PCR) experiments. Finally, through miRTarBase, miRDB, and RAID, the miRNAs were predicted to regulate key genes, respectively.

Results

A total of 345 common DEGs were identified and they were mainly related to spermatogenesis, insulin signaling pathway. Coexpression analysis of DEGs in GSE45885 yielded eight modules; MEblack and MEturquoise had the highest correlation with NOA. Six genes in MEturquoise and RNF141 in MEblack were identified as key genes. qRT-PCR experiments validated the differential expression of key genes between NOA and control. Furthermore, RNF141 was regulated by the largest number of miRNAs.

Conclusion

Our findings suggest that the significant change expression of key genes may be potential markers and therapeutic targets of NOA and may have some impact on the development of NOA.

Oxidative origin of sperm DNA fragmentation in the adult varicocele

PURPOSE

Sperm DNA fragmentation is a major cellular mechanism underlying varicocele-related male infertility. However, the type of DNA fragmentation - whether oxidative or of another nature - remains unknown. Thus, the aim of this study was to evaluate single- and double-stranded sperm DNA fragmentation, and oxidative-induced sperm DNA damage in men with varicocele.

MATERIALS AND METHODS

A cross-sectional study was performed, including 94 normozoospermic adults, of which 39 men without varicocele (controls) and 55 men with varicocele grades II or III, uni- or bilaterally. All men collected semen by masturbation. After semen analysis, the remaining volume was used for evaluation of three types of sperm DNA damage: (i) total DNA fragmentation, using an alkaline comet assay, (ii) double-stranded DNA fragmentation, using a neutral comet assay, and (iii) oxidative DNA damage, using an alkaline comet assay associated with the DNA glycosylase formamidopyrimidine enzyme. In each assay, percentage of sperm with any degree of DNA fragmentation, and with high DNA fragmentation were compared between the groups using an unpaired Student's t test or a Mann-Whitney test.

RESULTS

The varicocele group presented a higher rate of sperm with fragmented DNA (both any and high DNA fragmentation), considering single-stranded DNA fragmentation, double-stranded DNA fragmentation, or a combination of both, as well as oxidative-induced DNA fragmentation.

CONCLUSIONS

Patients with varicocele have an increase in sperm DNA fragmentation levels, particularly in oxidative stress-induced sperm DNA damage.

Seminal inflammasome activity in the adult varicocele

Varicocele has been hypothesized to lead to seminal inflammation, which in turn interferes with sperm function. Thus, the aim of this study was to investigate the role of inflammatory cytokines in the pathogenesis of decreased semen quality observed in adult men with varicocele, and to determine if varicocelectomy corrects these potential alterations. A prospective study was carried out including fifteen control men without varicocele and with normal semen quality and 15 men with varicocele with surgical indication. Men with varicocele grades II or III underwent microsurgical subinguinal varicocelectomy. Controls collected one semen sample and men with varicocele collected one before and one 6 months after the surgery. Semen analysis, sperm function, and seminal lipid peroxidation levels were assessed. Seminal plasma inflammasome activity was evaluated by ELISA assays for IL-1β, IL-18 and caspase-1 and by Western blotting for ASC (apoptosis-associated speck-like protein). Groups were compared by an unpaired Student's T test. Varicocelectomy samples were compared using a paired Student's T test (α = 5%). Men with varicocele had decreased semen quality, and increased seminal IL-1β levels, when compared to control men. Varicocelectomy decreased levels of caspase-1, IL-18, and IL1β. Thus, varicocelectomy improves sperm morphology and decreases seminal plasma inflammatory activity, after a six-month post-operative period.

Fertility Relevance Probability Analysis Shortlists Genetic Markers for Male Fertility Impairment

Impairment of male fertility is one of the major public health issues worldwide. Nevertheless, genetic causes of male sub- and infertility can often only be suspected due to the lack of reliable and easy-to-use routine tests. Yet, the development of a marker panel is complicated by the large quantity of potentially predictive markers. Actually, hundreds or even thousands of genes could have fertility relevance. Thus, a systematic method enabling a selection of the most predictive markers out of the many candidates is required. As a criterion for marker selection, we derived a gene-specific score, which we refer to as fertility relevance probability (FRP). For this purpose, we first categorized 2,753 testis-expressed genes as either candidate markers or non-candidates, according to phenotypes in male knockout mice. In a parallel approach, 2,502 genes were classified as candidate markers or non-candidates based on phenotypes in men. Subsequently, we conducted logistic regression analyses with evolutionary rates of genes (dN/dS), transcription levels in testis relative to other organs, and connectivity of the encoded proteins in a protein-protein interaction network as covariates. In confirmation of the procedure, FRP values showed the expected pattern, thus being overall higher in genes with known relevance for fertility than in their counterparts without corresponding evidence. In addition, higher FRP values corresponded with an increased dysregulation of protein abundance in spermatozoa of 37 men with normal and 38 men with impaired fertility. Present analyses resulted in a ranking of genes according to their probable predictive power as candidate markers for male fertility impairment. Thus, AKAP4, TNP1, DAZL, BRDT, DMRT1, SPO11, ZPBP, HORMAD1, and SMC1B are prime candidates toward a marker panel for male fertility impairment. Additional candidate markers are DDX4, SHCBP1L, CCDC155, ODF1, DMRTB1, ASZ1, BOLL, FKBP6, SLC25A31, PRSS21, and RNF17. FRP inference additionally provides clues for potential new markers, thereunder TEX37 and POU4F2. The results of our logistic regression analyses are freely available at the PreFer Genes website (https://prefer-genes.uni-mainz.de/).

Restoration of the apoptosis pathways' proteins levels after orchiectomy in testicular tumour patients

Seminal plasma proteins already demonstrated to reflect the testicular environment function and important regulatory mechanisms. However, it is crucial to understand which of these proteins participate in probable altered pathways in testicular germ cell tumours and after unilateral orchiectomy. In this study, we proposed to verify, by a multiplex approach, the levels of DNA damage and apoptosis pathways' proteins, in seminal plasma of men before and after unilateral orchiectomy, and also in control men. Comparing pre- and post-orchiectomy groups, just the apoptosis pathways' proteins presented different levels, in which Bad was lower and Bcl2, Akt, caspase-9, p53 and caspase-8 were higher after orchiectomy. When comparing pre- and post-orchiectomy groups with control, both presented lower levels of ChK1, Chk2, H2AX, p53 and p21, for DNA damage pathway. Regarding the apoptosis pathway, lower levels of JNK, Bcl2, Akt, caspase-9, p53 and caspase-8 and higher levels of Bad were observed before orchiectomy. The post-orchiectomy group did not differ from controls, demonstrating a probable restoration on its proteins levels. We can conclude that testicular tumours can alter both of the assessed pathways, and its removal is associated with a probable restoration of the apoptosis pathway.

One day is better than four days of ejaculatory abstinence for sperm function

According to the World Health Organization guidelines, ejaculatory abstinence (EA) of 2–7 days is recommended for semen analysis. This study aimed to determine how seminal quality may be affected by two EA periods from the same man. Seminal samples from 65 men were evaluated by conventional semen analysis and qualitative characteristics after 1 and 4 days of EA (two samples/man). The semen was qualitatively analyzed by examining oxidative activity (intracellular and seminal plasma), sperm function (acrosome integrity, mitochondrial activity, and nuclear DNA integrity), and epididymal function. As expected, samples collected after 1 day of EA showed a decrease in volume and sperm total number compared to samples collected after 4 days of EA. The sperm motility of the samples collected after 1 day of EA was better compared to samples collected after 4 days of EA. Oxidative activity measured was lower after 1 day of EA compared with those measured after 4 days of EA. With regards to sperm function, samples collected after 1 day of EA showed an increase in acrosome integrity, mitochondrial activity, and nuclear DNA integrity compared with samples collected after 4 days of EA. Epididymal function showed no difference between the two-time points. Although samples collected after 4 days of EA showed better results for sperm quantity, samples collected after 1 day of EA showed better qualitative results, including motility, oxidative activity, and sperm function. Thus, it can be concluded that sperm storage at the epididymal tail may make spermatozoa more susceptible to oxidative damage.

Exosome Composition and Seminal Plasma Proteome: A Promising Source of Biomarkers of Male Infertility

Infertility has become a global health issue, with approximately 50% of infertility cases generated by disorders in male reproduction. Spermatozoa are conveyed towards female genital tracts in a safe surrounding provided by the seminal plasma. Interestingly, this dynamically changing medium is a rich source of proteins, essential not only for sperm transport, but also for its protection and maturation. Most of the seminal proteins are acquired by spermatozoa in transit through exosomes (epididymosomes and prostasomes). The high number of seminal proteins, the increasing knowledge of their origins and biological functions and their differential expression in the case of azoospermia, asthenozoospermia, oligozoospermia and teratozoospermia or other conditions of male infertility have allowed the identification of a wide variety of biomarker candidates and their involvement in biological pathways, thus to strongly suggest that the proteomic landscape of seminal plasma may be a potential indicator of sperm dysfunction. This review summarizes the current knowledge in seminal plasma proteomics and its potentiality as a diagnostic tool in different degrees of male infertility.

Proteomic analysis of seminal plasma from bilateral varicocele patients indicates an oxidative state and increased inflammatory response

Seminal plasma is a rich source of proteins and serves as an ideal sample for proteomic analysis of male infertility. In varicocele-associated infertility, the contributory role of seminal plasma proteins specific to unilateral and bilateral varicocele is not clear. Furthermore, there is a lack of specific protein biomarker to differentiate bilateral from unilateral varicocele. The main objective is to identify the differentially regulated molecular and cellular pathways in bilateral varicocele. Furthermore, we intend to identify seminal plasma biomarkers to differentiate bilateral and unilateral varicocele patients in comparison with fertile healthy men. Global proteomic analysis of seminal plasma proteins has identified the functionality of differentially expressed proteins (DEPs) in varicocele patients. Bioinformatic analysis has revealed response to reactive oxygen species and oxidative stress, and tissue homeostasis as top process pathways that are affected in bilateral varicocele patients compared to fertile healthy men. In comparison with unilateral varicocele patients, inflammatory response pathways were dysregulated, especially interleukin 6 (IL-6) signaling and Janus kinase-signal transducer and activator of transcription (Jak-STAT) pathways, in bilateral varicocele patients, owing to the involvement of underexpressed DEPs. Key DEPs associated with oxidative stress (peroxiredoxin 2; PRDX2), DNA fragmentation (fatty acid synthase; FASN), and inflammatory response (fibronectin 1; FN1) validated by western blot analysis revealed differential expression of these proteins in unilateral and bilateral varicocele groups. Altered expression of DEPs and its association with key processes show that the seminal plasma homeostasis is compromised in bilateral varicocele patients. Furthermore, we propose PRDX2, FASN, and FN1 as potential noninvasive seminal plasma markers for the differentiation of unilateral and bilateral varicocele patients.

Proteomic Analysis in Seminal Plasma of Fertile Donors and Infertile Patients with Sperm DNA Fragmentation

Seminal plasma proteomics studies could represent a new approach for the determination of molecular elements driving male infertility, resulting in a better male infertility characterization. The aim of this study is to investigate proteomic differences in seminal plasma samples from fertile and infertile individuals. For that, semen samples were selected according to semen analysis, clinical pathology, and values of sperm DNA fragmentation (alkaline and neutral Comet assay and Sperm Chromatin Dispersion test). A total of 24 seminal plasma samples classified in four groups were processed: fertile donors (FD), recurrent miscarriage patients (RM), asthenoteratozoospermic patients (ATZ), and asthenoteratozoospermic patients with varicocele (ATZ-VAR). Results obtained by 2D-differential gel electrophoresis (2D-DIGE) revealed 26 spots significantly increased in fertile donors when compared to patient groups. Also, eight spots in the ATZ group and two in the ATZ-VAR group were decreased compared to the other groups. Twenty-eight proteins were identified by mass spectrometry (MS), most of them involved in metabolic and cellular processes and with a catalytic or binding function. Protein-protein interactions through Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) tool suggest that a large part of them were associated with each other. Furthermore, most of them were associated with ubiquitin C, indicating that it could play an important regulation role, resulting in a potential male infertility biomarker.

Proteomics and metabolomics - Current and future perspectives in clinical andrology

Proteomics and metabolomics are emerging as promising tools to investigate the molecular mechanisms associated with male infertility. Proteins and metabolites play a pivotal role in regulating the molecular pathways associated with physiological functions of spermatozoa. Semen analysis, physical examination and laboratory work up cannot identify the etiology of infertility in 30%-40% of cases, which are classified as idiopathic. Therefore, the application of proteomics and metabolomics in the field of andrology will aid to overcome the limitations of the standard semen analysis. Understanding the molecular pathways associated with male infertility will help in planning ad hoc treatments, contributing to the clinical management of infertile patients. In this review, proteomics and metabolomics studies on spermatozoa and seminal plasma are discussed with a focus on molecular biomarkers associated with male infertility-related conditions.

The triple role of glutathione S-transferases in mammalian male fertility

Male idiopathic infertility accounts for 15-25% of reproductive failure. One of the factors that has been linked to this condition is oxidative stress (OS), defined as the imbalance between antioxidants and reactive oxygen species. Amongst the different factors that protect the cell against OS, the members of the glutathione S-transferase (GST) superfamily play an important role. Interestingly, reduction or lack of some GSTs has been associated to infertility in men. Therefore, and to clarify the relationship between GSTs and male fertility, the aim of this work is to describe the role that GSTs play in the male reproductive tract and in sperm physiology. To that end, the present review provides a novel perspective on the triple role of GSTs (detoxification, regulation of cell signalling and fertilisation), and reports their localisation in sperm, seminal plasma and the male reproductive tract. Furthermore, we also tackle the existing correlation between some GST classes and male fertility. Due to the considerable impact of GSTs in human pathology and their tight relationship with fertility, future research should address the specific role of these proteins in male fertility, which could result in new approaches for the diagnosis and/or treatment of male infertility.

Seminal plasma protein networks and enriched functions in varicocele: Effect of smoking

To verify a possible synergistic effect of smoking and varicocele on the seminal plasma proteome and biological functions, a cross-sectional study was performed in 25 smokers and 24 nonsmokers. Samples were used for conventional semen analysis, functional analysis (DNA fragmentation, acrosome integrity and mitochondrial activity) and proteomics by a shotgun approach. Functional enrichment of biological pathways was performed in differentially expressed proteins. Smokers presented lower ejaculate volume (p = .027), percentage of progressively motile spermatozoa (p = .002), total sperm count (p = .039), morphology (p = .001) and higher percentage of immotile spermatozoa (p = .03), round cell (p = .045) and neutrophil count (p = .009). Smokers also presented lower mitochondrial activity and acrosome integrity and higher DNA fragmentation. We identified and quantified 421 proteins in seminal plasma, of which one was exclusive, 21 were overexpressed and 70 were underexpressed in the seminal plasma of smokers. The proteins neprilysin, beta-defensin 106A and histone H4A were capable of predicting the smoker group. Enriched functions were related to immune function and sperm machinery in testis/epididymis. Based on our findings, we can conclude that cigarette smoking leads to the establishment of inflammatory protein pathways in the testis/epididymis in the presence of varicocele that seems to act in synergy with the toxic components of the cigarette.

Seminal Plasma Proteome as an Indicator of Sperm Dysfunction and Low Sperm Motility in Chickens

Molecular mechanisms underlying sperm motility have not been fully explained, particularly in chickens. The objective was to identify seminal plasma proteins associated with chicken sperm motility by comparing the seminal plasma proteomic profile of roosters with low sperm motility (LSM, n = 4) and high sperm motility (HSM, n = 4). Using a label-free MS-based method, a total of 522 seminal plasma proteins were identified, including 386 (∼74%) previously reported and 136 novel ones. A total of 70 differentially abundant proteins were defined, including 48 more-abundant, 15 less-abundant, and seven proteins unique to the LSM group (specific proteins). Key secretory proteins like less-abundant adhesion G-protein coupled receptor G2 (ADGRG2) and more-abundant serine peptidase inhibitor Kazal-type 2 (SPINK2) in the LSM suggested that the corresponding secretory tissues played a crucial role in maintaining sperm motility. Majority (80%) of the more-abundant and five specific proteins were annotated to the cytoplasmic domain which might be a result of higher plasma membrane damage and acrosome dysfunction in LSM. Additionally, more-abundant mitochondrial proteins were detected in LSM seminal plasma associated with lower spermatozoa mitochondrial membrane potential (ΔΨm) and ATP concentrations. Further studies showed that the spermatozoa might be suffering from oxidative stress, as the amount of spermatozoa reactive oxygen species (ROS) were largely enhanced, seminal malondialdehyde (MDA) concentrations were increased, and the seminal plasma total antioxidant capacity (T-AOC) were decreased. Our study provides an additional catalogue of chicken seminal plasma proteome and supports the idea that seminal plasma could be as an indicator of spermatozoa physiology. More-abundant of acrosome, mitochondria and sperm cytoskeleton proteins in the seminal plasma could be a marker of sperm dysfunction and loss of motility. The degeneration of spermatozoa caused by the reduced seminal T-AOC and enhanced oxidative stress might be potential determinants of low sperm motility. These results could extend our understanding of sperm motility and sperm physiology regulation.

Proteomic Analyses of Human Sperm Cells: Understanding the Role of Proteins and Molecular Pathways Affecting Male Reproductive Health

Human sperm proteomics research has gained increasing attention lately, which provides complete information about the functional state of the spermatozoa. Changes in the sperm proteome are evident in several male infertility associated conditions. Global proteomic tools, such as liquid chromatography tandem mass spectrometry and matrix-assisted laser desorption/ionization time-of-flight, are used to profile the sperm proteins to identify the molecular pathways that are defective in infertile men. This review discusses the use of proteomic techniques to analyze the spermatozoa proteome. It also highlights the general steps involved in global proteomic approaches including bioinformatic analysis of the sperm proteomic data. Also, we have presented the findings of major proteomic studies and possible biomarkers in the diagnosis and therapeutics of male infertility. Extensive research on sperm proteome will help in understanding the role of fertility associated sperm proteins. Validation of the sperm proteins as biomarkers in different male infertility conditions may aid the physician in better clinical management.

Glutathione S-Transferases Play a Crucial Role in Mitochondrial Function, Plasma Membrane Stability and Oxidative Regulation of Mammalian Sperm

Glutathione S-transferases (GSTs) are essential sperm antioxidant enzymes involved in cell protection against oxidative stress and toxic chemicals, preserving sperm function and fertilising ability. Artificial insemination (AI) in pigs is commonly carried out through the use of liquid-stored semen at 17 °C, which not only reduces sperm metabolic activity but also sperm quality and AI-farrowing rates within the 72 h of storage. While one may reasonably suggest that such enzymes are implicated in the physiology and maintenance of mammalian sperm function during liquid-storage, no previous studies conducted on any species have addressed this hypothesis. Therefore, the objective of the present work was to characterise the presence and function of sperm GSTs in mammalian sperm, using the pig as a model. In this regard, inhibition of such enzymes by ethacrynic acid (EA) during semen storage at 17 °C was performed to evaluate the effects of GSTs in liquid-preserved boar sperm by flow cytometry, immunofluorescence, and immunoblotting analysis. The results of this study have shown, for the first time in mammalian species, that the inhibition of GSTs reduces sperm quality and functionality parameters during their storage at 17 °C. These findings highlight the key role of such enzymes, especially preserving mitochondrial function and maintaining plasma membrane stability. In addition, this study has identified and localised GSTM3 in the tail and equatorial subdomain of the head of boar sperm. Finally, this study has set grounds for future investigations testing supplementation of semen extenders with GSTs, as this may improve fertility outcomes of swine AIs.

Characterization of seminal plasma proteomic alterations associated with the IVF and rescue-ICSI pregnancy in assisted reproduction

BACKGROUND

Seminal plasma is a promising diagnostic fluid for male infertility. In assisted reproduction, the seminal plasma-based characteristics of normozoospermic men achieving successful clinical pregnancy through rescue intracytoplasmic sperm injection after in vitro fertilization failure remain unclear.

OBJECTIVE

To identify potential seminal plasma proteins to contribute to a new understanding of unexplained male factor infertility.

MATERIALS AND METHODS

An approach with isobaric tags for relative and absolute quantification labeling coupled with liquid chromatography matrix-assisted laser desorption ionization mass spectrometry was applied to investigate differentially expressed proteins in the seminal plasma of a rescue intracytoplasmic sperm injection pregnancy group versus an in vitro fertilization pregnancy group of normozoospermic men.

RESULT(S)

The present work revealed seventy-three differentially expressed seminal plasma proteins between the in vitro fertilization and rescue intracytoplasmic sperm injection groups. Forty-five proteins were upregulated, and 28 proteins were downregulated in the rescue intracytoplasmic sperm injection group compared with the in vitro fertilization group. Bioinformatics analyses showed that these altered proteins were involved in various functions, including the kallikrein-related proteolytic cascade, immune response, and heparin binding. Furthermore, the validity of the proteomic results was verified by Western blot analysis of the proteins (lactoferrin [LTF], fibronectin [FN1], creatine kinase B type [CKB], kallikrein-2 [KLK2], aminopeptidase N [ANPEP], extracellular matrix protein 1 [ECM1], glycodelin [PAEP], alpha-1-antitrypsin [SERPINA1], and semenogelin-1 [SEMG1]) and immunofluorescence. Moreover, 16% of the seminal plasma proteins identified in the present work have not been reported in previous studies.

DISCUSSION

This panel of altered seminal plasma proteins associated with unexplained male factor infertility might have clinical relevance and may be useful in the diagnosis and prognosis of idiopathic infertility in in vitro fertilization.

CONCLUSIONS

Our work not only provides a new complementary high-confidence dataset of seminal plasma proteins but also shines new light onto the molecular characteristics of seminal plasma from normozoospermic men with different assisted reproductive outcomes.

Comprehensive immune complexome analysis detects disease-specific immune complex antigens in seminal plasma and follicular fluids derived from infertile men and women

BACKGROUND

Autoimmune reactions and subsequent inflammation may underlie spermatogenic dysfunction and endometriosis-related infertility. The aim of this study is to identify disease-specific antigens in immune complexes (ICs) in seminal plasma (SP) and in follicular fluid (FF).

METHODS

Immune complexome analysis, in which nano-liquid chromatography-tandem mass spectrometry is employed to comprehensively identify antigens incorporated into ICs in biological fluids, was performed for specimens collected from infertile couples undergoing assisted reproduction. Forty-two male patients consisting of subjects with oligozoospermia (n = 6), asthenozoospermia (n = 8), and normal semen analysis (n = 28). Fifty-eight female patients consisting of subjects with ovarian endometriosis (n = 10) and control women without disease (n = 48).

RESULTS

Four disease-specific antigens were identified in subjects with oligozoospermia, while five disease-specific antigens were detected in subjects with asthenozoospermia, some of which are involved in sprematogenesis. Eight antigens were detected only in subjects with endometriosis.

CONCLUSION

Functional characteristics of disease-specific antigens were found to correspond to the pathogenesis of male and female infertility. The formation of ICs may contribute to spermatogenic dysfunction and endometriosis-related infertility via loss of function of the related proteins. Immune complexome analysis is expected to be a valuable tool for the investigation of novel diagnostic methods and treatment strategies for infertility.

The seminal acrosin-inhibitor ClTI1/SPINK2 is a fertility-associated marker in the chicken

The seminal plasma is a very complex fluid, which surrounds sperm in semen. It contains numerous proteins including proteases and protease inhibitors that regulate proteolytic processes associated with protein activation and degradation. We previously identified a seminal protein, chicken liver trypsin inhibitor 1 (ClTI-1) over expressed in semen of roosters with high fertility, suggesting a role in male fertility. In the present study, we showed that ClTI-1 gene is actually SPINK2. Using normal healthy adult roosters, we showed that SPINK2 amount in seminal plasma was positively correlated with male fertility in chicken lines with highly contrasted genetic backgrounds (broiler and layer lines). Using affinity chromatography combined to mass spectrometry analysis and kinetic assays, we demonstrated for the first time that two chicken acrosin isoforms (acrosin and acrosin-like proteins) are the physiological serine protease targets of SPINK2 inhibitor. SPINK2 transcript was overexpressed all along the male tract, and the protein was present in the lumen as expected for secreted proteins. Altogether, these data emphasize the role of seminal SPINK2 Kazal-type inhibitor as an important actor of fertility in birds through its inhibitory action on acrosin isoforms proteins.

Stable-protein Pair Analysis as A Novel Strategy to Identify Proteomic Signatures: Application To Seminal Plasma From Infertile Patients

Our aim was to define seminal plasma proteome signatures of infertile patients categorized according to their seminal parameters using TMT-LC-MS/MS. To that extent, quantitative proteomic data was analyzed following two complementary strategies: (1) the conventional approach based on standard statistical analyses of relative protein quantification values; and (2) a novel strategy focused on establishing stable-protein pairs. By conventional analyses, the abundance of some seminal plasma proteins was found to be positively correlated with sperm concentration. However, this correlation was not found for all the peptides within a specific protein, bringing to light the high heterogeneity existing in the seminal plasma proteome because of both the proteolytic fragments and/or the post-translational modifications. This issue was overcome by conducting the novel stable-protein pairs analysis proposed herein. A total of 182 correlations comprising 24 different proteins were identified in the normozoospermic-control population, whereas this proportion was drastically reduced in infertile patients with altered seminal parameters (18 in patients with reduced sperm motility, 0 in patients with low sperm concentration and 3 in patients with no sperm in the ejaculate). These results suggest the existence of multiple etiologies causing the same alteration in seminal parameters. Additionally, the repetition of the stable-protein pair analysis in the control group by adding the data from a single patient at a time enabled to identify alterations in the stable-protein pairs profile of individual patients with altered seminal parameters. These results suggest potential underlying pathogenic mechanisms in individual infertile patients, and might open up a window to its application in the personalized diagnostic of male infertility.

Semen levels of matrix metalloproteinase (MMP) and tissue inhibitor of metallorproteinases (TIMP) protein families members in men with high and low sperm DNA fragmentation

Matrix Metalloproteinases (MMPs) and their regulators – Tissue Inhibitors of Matrix Metalloproteinases (TIMPs) – participate in extracellular matrix remodeling, fibrosis, and semen liquefaction, as well as to inflammatory activity. Seminal plasma has been shown to contain MMPs (MMP-2 and MMP-9) and TIMPs (TIMP-1 and TIMP-2). Also, a link between MMPs gene expression and excessive reactive oxygen species (ROS) has been established. In semen, ROS are associated with altered sperm function and increased DNA fragmentation. In this study, it is hypothesized that seminal MMPs and TIMPs levels are associated with sperm DNA fragmentation due to the fact that MMPs have been associated with semen quality. We also hypothesized that these proteins could predict DNA fragmentation status in sperm. Therefore, this study set out to verify if sperm DNA fragmentation levels relate to seminal levels of members of the MMP and TIMP protein families. The High sperm DNA fragmentation group presented lower seminal plasma levels of MMP-2, MMP-7, TIMP-1, TIMP-2 and TIMP-4 when compared to Low sperm DNA fragmentation group. Also, samples in the high sperm DNA fragmentation group presented higher acrosome integrity and lower mitochondrial activity levels when compared to low sperm DNA fragmentation samples. In the logistic regression analysis, MMP-2, MMP-7, and TIMP-4 classified samples as low and high sperm DNA fragmentation, with an overall model fit of 74.5%. Results from this study may demonstrate a specific inflammatory mechanism in samples with high sperm DNA fragmentation. This, in turn, can lead to the development of new studies regarding this mechanism and, in the future, create an opportunity to treat these patients for sperm DNA fragmentation by treating inflammatory seminal activity.

An in silico analysis of human sperm genes associated with asthenozoospermia and its implication in male infertility

Asthenozoospermia is the most common clinical symptom of male infertility. Molecular markers associated with asthenozoospermia spermatozoa are scarcely identified. The objective of this study was to screen the differentially expressed genes (DEGs) in asthenozoospermia spermatozoa and assess the underlying bioinformatics roles in regulation of sperm quality.Based on gene expression omnibus (GEO) database, the GSE22331, GSE1133, and GSE4193 expression profile data were downloaded. The DEGs of asthenozoospermia spermatozoa were identified. Germ cell specific genes in DEGs were further screened. Then, gene ontology (GO) and over-representation analysis of DEGs were performed, followed by protein-protein interaction (PPI) network analysis. Expressions of selected genes of TEX11, ADAMTS5, ASRGL1, GMCL1, PGK2, KLHL10 in normozoospermia and asthenozoospermia spermatozoa were identified using real time Reverse Transcription-Polymerase Chain Reaction (RT-PCR).A total of 1323 DEGs were identified, including 1140 down-regulated genes. Twenty one and 96 down-regulated genes were especially expressed in spermatogonia and round spermatids, suggesting their testicular origins and influences on sperm quality. Bioinformatics analysis showed enriched functions of ubiquitin-like protein transferase or protein binding activities in down-regulated genes. Expressions of selected genes were validated by RT-PCR, which was consistent with bioinformatical results.The present study provided a novel insight into the understanding of sperm quality, and a potential method and dataset for the diagnosis and assessment of sperm quality in the event of male infertility.

Comprehensive proteomics analysis of exosomes derived from human seminal plasma

Exosomes are membranous nanovesicles of endocytic origin that carry and transfer regulatory bioactive molecules and mediate intercellular communication between cells and tissues. Although seminal exosomes have been identified in human seminal plasma, their exact composition and possible physiologic function remain unknown. The objective of this study was to perform a comprehensive proteomics analysis of exosomes derived from human seminal plasma. Seminal exosomes were isolated and purified from 12 healthy donors using a 30% sucrose cushion‐based exosome‐isolation protocol, followed by characterization by western blot, transmission electron microscopy, and nanoparticle tracking analysis before performing extensive liquid chromatography tandem mass spectrometry proteomics analysis. The identified proteins were analyzed by bioinformatics analysis, and seminal exosomes‐associated proteins were selectively validated by western blot. A total of 1474 proteins were identified in all seminal exosomes samples, with Gene Ontology analysis demonstrating that these identified seminal exosomes‐associated proteins were mostly linked to ‘exosomes,’ ‘cytoplasm,’ and ‘cytosol.’ Bioinformatics analysis indicated that these proteins were mainly involved in biologic processes, including metabolism, energy pathways, protein metabolism, cell growth and maintenance, and transport. Of these identified proteins, PHGDH, LGALS3BP, SEMG1, ACTB, GAPDH, and the exosomal‐marker protein ALIX were validated by western blot. This study provided a more comprehensive description of the seminal exosomes proteome and could also be a resource for further screening of biomarkers and comparative proteomics studies, including those associated with male infertility and prostate cancer.

Understanding the seminal plasma proteome and its role in male fertility

Seminal plasma is a complex fluid comprised of secretions from the seminal vesicles, the prostate, bulbourethral glands and from the seminiferous tubule lumen / epididymides / vasa deferentia. While it has been established that seminal plasma serves not only as a medium to carry, protect, and nourish sperm after ejaculation up to fertilization, but also as a functional modulator of sperm function, there is still a need to properly characterize the molecular make-up of seminal plasma in fertile men, and to understand how this is altered in different causes of male infertility. The main purpose of this manuscript was to review articles that studied the human seminal plasma proteome, ranging from characterizing a fertile seminal plasma proteomic map to studies comparing seminal plasma from fertile and infertile men, and comparing seminal plasma of fertile or normozoospermic men to a diverse range of biological causes for male infertility. Finally, this review has focused on the association between semen and sperm functional quality and the seminal plasma proteome, in order to demonstrate cellular and molecular mechanisms of male infertility. Due to the untargeted nature of the majority of the studies presented in this review, and to the diverse range of techniques utilized to study the seminal plasma proteomic composition, many differentially expressed proteins were observed. However, in general, it seems that there is a seminal plasma proteome associated to male fertility, and that different biological conditions or cellular phenotypes shift its pathways away from its homeostatic condition to altered energy production pathways. Moreover, it seems there is an inflammatory component to the seminal plasma of infertile men. In conclusion, there are a number of studies focused on the proteomic composition of human seminal plasma; downstream confirmatory studies will help to understand specific pathways of infertility in different biological conditions.

Effect of in vitro vitamin E (alpha-tocopherol) supplementation in human spermatozoon submitted to oxidative stress

The aim of this study was to evaluate the antioxidant effect of in vitro supplementation with vitamin E in human spermatozoon incubated with an oxidative stress inducer. In this study, semen samples from 30 patients were collected and with one aliquot we performed semen analysis according to WHO. The remaining volume was divided into four aliquots: group C: incubated with BWW medium; group I: incubated with 5 mmol 1-1 hydrogen peroxide; group A: incubated with 40 μmol 1-1 vitamin E; and group AI: incubated with both them. After incubations, sperm functional analyses were performed and included: evaluation of oxidative stress, acrosome integrity, mitochondrial activity and DNA fragmentation. Groups were compared using a Friedman test with Bonferroni post hoc (α = 5%). In this study, we observed that in group I there was a decrease in acrosome integrity and mitochondrial activity, and an increase in DNA fragmentation, when compared to group C. Group AI showed an increase in acrosome integrity and mitochondrial activity when compared with group I. Based on our findings, we conclude that the vitamin E supplementation had a positive effect in protecting human spermatozoon from induced oxidative stress.

Update on the proteomics of male infertility: A systematic review

Objective

To assess the role of differentially expressed proteins as a resource for potential biomarker identification of infertility, as male infertility is of rising concern in reproductive medicine and evidence pertaining to its aetiology at a molecular level particularly proteomic as spermatozoa lack transcription and translation. Proteomics is considered as a major field in molecular biology to validate the target proteins in a pathophysiological state. Differential expression analysis of sperm proteins in infertile men and bioinformatics analysis offer information about their involvement in biological pathways.

Materials and methods

Literature search was performed on PubMed, Medline, and Science Direct databases using the keywords ‘sperm proteomics’ and ‘male infertility’. We also reviewed the relevant cross references of retrieved articles and included them in the review process. Articles written in any language other than English were excluded.

Results

Of 575 articles identified, preliminary screening for relevant studies eliminated 293 articles. At the next level of selection, from 282 studies only 80 articles related to male infertility condition met the selection criteria and were included in this review.

Conclusion

In this molecular era, sperm proteomics has created a platform for enhanced understanding of male reproductive physiology as a potential tool for identification of novel protein biomarkers related to sperm function in infertile men. Therefore, it is believed that proteomic biomarkers can overcome the gaps in information from conventional semen analysis that are of limited clinical utility.

Gender proteomics II. Which proteins in sexual organs

In continuity with the review dealing with differences by gender in non-sexual organs [1], this review collects data on the proteomes of the sexual organs as involved in human reproduction, under both physiological and pathological conditions. It also collects data on the tissue structures and biological fluids typical of pregnancy, such as placenta and amniotic fluid, as well as what may be tested on preimplantation embryos during medically assisted reproduction. The review includes as well mention to all fluids and secretions connected with sex organs and/or reproduction, including sperm and milk, to exemplify two distinctive items in male and female physiology.

SIGNIFICANCE

The causes of infertility are only incompletely understood; the same holds for the causes, and even the early markers, of the most frequent complications of pregnancy. To these established medical challenges, present day practice adds new issues connected with medically assisted reproduction. Omics approaches, including proteomics, are building the database for basic knowledge to possibly translate into clinical testing and eventually into medical routine in this critical branch of health care.

The Use of Proteomics in Assisted Reproduction

Despite the explosive increase in the use of Assisted Reproductive Technologies (ART) over the last 30 years, their success rates remain suboptimal. Proteomics is a rapidly-evolving technology-driven science that has already been widely applied in the exploration of human reproduction and fertility, providing useful insights into its physiology and leading to the identification of numerous proteins that may be potential biomarkers and/or treatment targets of a successful ART pregnancy. Here we present a brief overview of the techniques used in proteomic analyses and attempt a comprehensive presentation of recent data from mass spectrometry-based proteomic studies in humans, regarding all components of ARTs, including the male and female gamete, the derived zygote and embryo, the endometrium and, finally, the ART offspring both pre- and postnatally.

Biochemical components of seminal plasma and their correlation to the fresh seminal characteristics in Marwari stallions and Poitou jacks

AIM

To investigate various biochemical components of seminal plasma in Marwari stallions and Poitou Jacks and to find out their correlation with that of the seminal characteristics.

MATERIALS AND METHODS

In this study, semen was collected from six Marwari stallions and six Poitou jacks aged from 4 to 6 years and with known fertility status. The semen collection from the stallions were collected during the breeding season, i.e., between the months of April and June. From the collected semen ejaculates, we estimated the values of some biochemical components, viz., total protein content, total lipid content, and enzymes such as glutamic pyruvic transaminase (GPT), glutamic oxaloacetic transaminase (GOT), alkaline phosphatase (ALP), acid phosphatase (ACP), and lactate dehydrogenase (LDH) as well as concentrations of glucose, cholesterol, total calcium (Ca), and phosphorus (P) and correlations among different seminal parameters were statistically examined using the Pearson correlation coefficient.

RESULTS

In this study, we found positive correlations between semen volume as well as sperm concentration and GOT, GPT, ALP and ACP for both the group stallions. Significant correlation between motility and glucose, GOT and GPT could be an indication for their role metabolism and protection against free radicals to the spermatozoa.

CONCLUSION

Based on the results, it is concluded that there is a positive correlation between some biochemical values such as glucose, Ca, ALP, and LDH and seminal parameters which play a key role in capacitation and onward movement of the spermatozoa.

Fatty acid content in epididymal fluid and spermatozoa during sperm maturation in dogs

Background

During sperm maturation, there is a reorganization of fatty acids from plasmatic membrane of the spermatozoa, which allows higher membrane integrity and acquisition of sperm motility. However, the fatty acid profile during sperm maturation remains unclear in dogs. Thus, the aim of this study was to identify the fatty acids from the epididymal spermatozoa and plasma during the sperm maturation, and observed changes in the motility and plasmatic membrane parameters. Twenty one adult dogs were used, subsequently to bilateral orchiectomy and epididymal storage, sperm samples were collected from the different segments of the epididymis. Samples were evaluated for conventional microscopy, computer-assisted motility analysis, sperm plasma membrane permeability and the fatty acid analysis (lipids were extracted, transmethylated and analyzed by chromatography).

Results

Caput and corpus sperm showed lower values for the motility variables evaluated and plasmatic membrane integrity, indicating different levels of the fatty acids organization. Saturated, monounsaturated and polyunsaturated fatty acids were in higher concentrations in the spermatozoa from epididymis cauda. Highlighting the presence of caprylic, stearic and docosahexaenoic acids.

Conclusions

These findings demonstrate the influence of the fatty acid profile during sperm maturation, assigning physical and chemical changes in sperm cells, essential for fertilization.