Study of the effect of varicocelectomy on sperm proteins expression in patients with varicocele and poor sperm quality by using two-dimensional gel electrophoresis

Seminal plasma proteomics as putative biomarkers for male infertility diagnosis

Male infertility represents a significant global public health issue that is currently emerging as a prominent research focus. Presently, laboratories adhere to the guidelines outlined by the World Health Organization (WHO) manuals for conducting routine semen analysis to diagnose male infertility. However, the accuracy of results in predicting sperm quality and fertility is limited because some individuals with a normal semen analysis report, an unremarkable medical history, and a physical examination may still experience infertility. As a result, the importance of employing more advanced techniques to investigate sperm function and male fertility in the treatment of male infertility and/or subfertility becomes apparent. The standard test for evaluating human semen has been improved by more complex tests that look at things like reactive oxygen species (ROS) levels, total antioxidant capacity (TAC), sperm DNA fragmentation levels, DNA compaction, apoptosis, genetic testing, and the presence and location of anti-sperm antibodies. Recent discoveries of novel biomarkers have significantly enriched our understanding of male fertility. Moreover, the notable biological diversity among samples obtained from the same individual complicates the efficacy of routine semen analysis. Therefore, unraveling the molecular mechanisms involved in fertilization is pivotal in expanding our understanding of factors contributing to male infertility. By understanding how these proteins work and what role they play in sperm activity, we can look at the expression profile in men who can't have children to find diagnostic biomarkers. This review examines the various sperm and seminal plasma proteins associated with infertility, as well as proteins that are either deficient or exhibit aberrant expression, potentially contributing to male infertility causes.

Does Varicocele Repair Improve Conventional Semen Parameters? A Meta-Analytic Study of Before-After Data

PURPOSE

The purpose of this meta-analysis is to study the impact of varicocele repair in the largest cohort of infertile males with clinical varicocele by including all available studies, with no language restrictions, comparing intra-person conventional semen parameters before and after the repair of varicoceles.

MATERIALS AND METHODS

The meta-analysis was performed according to PRISMA-P and MOOSE guidelines. A systematic search was performed in Scopus, PubMed, Cochrane, and Embase databases. Eligible studies were selected according to the PICOS model (Population: infertile male patients with clinical varicocele; Intervention: varicocele repair; Comparison: intra-person before-after varicocele repair; Outcome: conventional semen parameters; Study type: randomized controlled trials [RCTs], observational and case-control studies).

RESULTS

Out of 1,632 screened abstracts, 351 articles (23 RCTs, 292 observational, and 36 case-control studies) were included in the quantitative analysis. The before-and-after analysis showed significant improvements in all semen parameters after varicocele repair (except sperm vitality); semen volume: standardized mean difference (SMD) 0.203, 95% CI: 0.129-0.278; p<0.001; I²=83.62%, Egger's p=0.3329; sperm concentration: SMD 1.590, 95% CI: 1.474-1.706; p<0.001; I²=97.86%, Egger's p<0.0001; total sperm count: SMD 1.824, 95% CI: 1.526-2.121; p<0.001; I²=97.88%, Egger's p=0.0063; total motile sperm count: SMD 1.643, 95% CI: 1.318-1.968; p<0.001; I²=98.65%, Egger's p=0.0003; progressive sperm motility: SMD 1.845, 95% CI: 1.537%-2.153%; p<0.001; I²=98.97%, Egger's p<0.0001; total sperm motility: SMD 1.613, 95% CI 1.467%-1.759%; p<0.001; l2=97.98%, Egger's p<0.001; sperm morphology: SMD 1.066, 95% CI 0.992%-1.211%; p<0.001; I²=97.87%, Egger's p=0.1864.

CONCLUSIONS

The current meta-analysis is the largest to date using paired analysis on varicocele patients. In the current meta-analysis, almost all conventional semen parameters improved significantly following varicocele repair in infertile patients with clinical varicocele.

Testicular heat stress, a historical perspective and two postulates for why male germ cells are heat sensitive

Herein, we compare the different experimental regimes used to induce testicular heat stress and summarise their impact on sperm production and male fertility. Irrespective of the protocol used, scrotal heat stress causes loss of sperm production. This is first seen 1-2 weeks post heat stress, peaking 4-5 weeks thereafter. The higher the temperature, or the longer the duration of heat, the more pronounced germ cell loss becomes, within extreme cases this leads to azoospermia. The second, and often underappreciated impact of testicular hyperthermia is the production of poor-quality spermatozoa. Typically, those cells that survive hyperthermia develop into morphologically abnormal and poorly motile spermatozoa. While both apoptotic and non-apoptotic pathways are known to contribute to hyperthermic germ cell loss, the mechanisms leading to formation of poor-quality sperm remain unclear. Mechanistically, it is unlikely that testicular hyperthermia affects messenger RNA (mRNA) abundance, as a comparison of four different mammalian studies shows no consistent single gene changes. Using available evidence, we propose two novel models to explain how testicular hyperthermia impairs sperm formation. Our first model suggests aberrant alternative splicing, while the second model proposes a loss of RNA repression. Importantly, neither model requires consistent changes in RNA species.

ATP5D Is a Potential Biomarker for Male Fertility

Background

Infertility is a global medical and social problem that affects human health and social development. At present, about 15% of couples of the right age in the world are infertile. As all we know, genetic defects are the most likely underlying cause of the pathology. ATP5D is also known as the delta subunit of mitochondrial ATP synthase. Mitochondria maintain sperm vitality, capacitation, acrosome reaction, and DNA integrity through ATP. Mitochondrial damage can trigger energy synthesis disorders, resulting in decreased sperm quality and function or even disappearance. The specific role of ATP5D in regulation of the male reproductive system remains elusive.

Methods

In this study, semen from normal and infertile males were collected and their indicators were examined by analysis of routine sperm parameters; ATP5D protein content in semen was examined by ELISA. Singer sequencing was used to detect whether there was a mutated of ATP5D in semen. Meanwhile, ATP5D knockout (KO) and knockin (KI) male mice were selected at 8-12 weeks of age and mated with adult wild-type (WT) female mice for more than two months to assess their fertility and reproductive ability. Morphological changes in tissues such as testes and epididymis were observed by HE staining; spermatozoa were taken from the epididymis of the mice; sperm counts were performed and morphological changes were observed by Diff-Quik staining.

Results

The results showed that the expression of ATP5D in infertile males was significantly lower than that in normal males (P < 0.001) and the normal morphology rate of spermatozoa was much lower than that of normal males, and the sequencing results showed no mutations. The animal reproductive experiments showed no significant changes in the number of fertility in KO/KI mice compared with WT mice, but the duration of fertility was significantly longer (P = 0.02). The testicular cells in KO mice were loosely arranged and disorganized, the lumen was larger, the interstitial cells were atrophied, and the number of spermatozoa was reduced and the malformation rate was higher in WT males. This suggests that ATP5D is an essential protein for sperm formation and fertility in male mice and may be used as a biomarker of male fertility.

Conclusion

This study found ATP5D correlated with male infertility and the expression levels were significantly reduced in the seminal plasma of all male infertile patients without gene mutations. KO male significantly prolonged fertility time and impaired testicular histomorphology. This suggests that ATP5D may be associated with spermatogenic function and fertility in male mice and may be used as a biomarker for male fertility. Future studies are required to elucidate the potential mechanisms. The trial registration number is KLL-2021-266.

Assessment of the Impact Induced by Different Incubation Time, Storage Time, Storage Medium and Thawing Methods on Sperm DNA Fragmentation Assay: A Before-After Study

Background

The sperm DNA fragmentation has been considered an important index in the field of male infertility.

Aims

Our study aims to evaluate the impact of different factors, including incubation time, storage time, storage medium and method of thawing, on DNA fragmentation of semen samples.

Settings and Design

This study was designed as a before-after study in five experiments.

Materials and Methods

Experiment 1 was conducted to assess the effect of storage time in liquid nitrogen on 15 semen samples. In experiment 2, DNA fragmentation was performed on 10 semen samples with different incubation times before freezing. In experiments 3, 4, two different storage media and thawing methods were applied respectively in two separate groups, each containing 30 samples and the DNA fragmentation index (DFI) was measured using the sperm chromatin structure assay method.

Statistical Analysis

Data were analysed using Stata version 11.

Results

There was a significant increase in sperm DNA fragmentation of samples stored in liquid nitrogen for 1 month. This increase occurred in the first 2 weeks. Furthermore, our results showed a significant increase in the DFI after 120 min of incubation at room temperature (RT) and also thawing in RT separately.

Conclusion

It is better to use fresh samples to measure DNA fragmentation up to 2 h after ejaculation to achieve more accurate results. Furthermore, if sperm freezing is inevitable, the use of a water bath (37°C) to thaw will be the most appropriate option, as it can lead to less DNA damage.

Prediction of semen analysis parameters improvement after varicocelectomy using 1 H NMR-based metabonomics assays

BACKGROUND

Varicocele is the most common correctable cause of male infertility, however, predicting varicocelectomy outcomes is difficult. "Omics" techniques have been increasingly used to develop new diagnostic and prognostics tools for several male infertility causes, and could be applied to study varicocele.

OBJECTIVES

To create metabolomics models capable of segregating men who improved semen analysis (SA) parameters or achieved natural pregnancy after microsurgical varicocelectomy (MV) from those who did not, using Hydrogen-1 nuclear magnetic resonance (¹ H NMR) spectra of seminal plasma of pre-operative samples.

MATERIAL AND METHODS

We recruited 29 infertile men with palpable varicocele. ¹ H NMR spectra of seminal plasma were obtained from pre-operative samples and used to create metabonomics models. Improvement was defined as an increase in the total motile progressive sperm count (TMC) of the post-operative SA when compared to the baseline, and pregnancy was assessed during 24 months after MV.

RESULTS

Using Linear Discriminant Analysis (LDA), we created a model that discriminated the men who improved SA from those who did not with accuracy of 93.1%. Another model segregated men who achieved natural pregnancy from men who did not. We identified 7 metabolites that were important for group segregation: caprylate, isoleucine, N-acetyltyrosine, carnitine, N-acetylcarnitine, creatine and threonine.

DISCUSSION

We described the use of metabonomics model to predict with high accuracy the outcomes of MV in infertile men with varicocele. The most important metabolites for groups segregation are involved in energy metabolism and oxidative stress response, highlighting the pivotal role of these mechanisms in the pathophysiology of varicocele.

CONCLUSIONS

¹ H NMR spectroscopy of seminal plasma can be used in conjunction with multivariate statistical tools to create metabonomics models useful segregate men with varicocele based on the reproductive outcomes of MV. These models may help counseling infertile men with varicocele regarding their prognosis after surgery. This article is protected by copyright. All rights reserved.

SERPIN A5 may have a potential as a biomarker in reflecting the improvement of semen quality in infertile men who underwent varicocele repair

We aimed to identify proteins that were differentially regulated in spermatozoal samples collected from fertile healthy men (FHM) and infertile patients with varicocele (IFPV) before and after varicocelectomy. Seminal samples were collected from 20 IFPV before and after varicocelectomy and from 14 FHM as controls. Samples underwent seminal examination and proteomic analysis. Extracted spermatozoal proteins were analysed using two-dimensional gel electrophoresis, and differentially regulated spermatozoal proteins (DRSPs) were identified. In particular, attention was placed on those DRSPs in which the concentration changed after varicocelectomy and corrected to approximate levels observed in FHM. Varicocelectomy significantly improved the sperm count and concentration in IFPV (p < 0.05). Proteomic analysis showed that 11 DRSPs were identified when comparisons were made among the three groups. Among these 11 proteins, change in the SERPIN A5 concentrations was notable because it was 100-fold downregulated in pre-operative IFPV samples and nearly resembled to control concentrations following varicocelectomy. Western blot analysis using an anti-SERPIN antibody validated the changes observed in SERPIN A5 levels before and after varicocelectomy operation. Increase in SERPIN A5 after varicocelectomy may be due to improvement in semen quality, suggesting that SERPIN A5 is a potential seminal biomarker for assessment of semen quality in varicocele-related infertility.

Stress response pathways in the male germ cells and gametes

The unfolded protein response (UPR) is a conserved and essential cellular pathway involved in protein quality control that is activated in response to several cellular stressors such as diseases states, ageing, infection and toxins. The cytosol, endoplasmic reticulum (ER) and mitochondria are continuously exposed to new proteins and in situations of aberrant protein folding; one of three lines of defence may be activated: (i) heat-shock response, (ii) mitochondrial UPR and (iii) ER UPR. These pathways lead to different signal transduction mechanisms that activate or upregulate transcription factors that, in turn, regulate genes that increase the cell's ability to correct the conformation of poorly folded proteins or, ultimately, lead to apoptosis. Despite the recent progress in understanding such biological processes, few studies have focused on the implications of the UPR in male infertility, highlighting the need for a first approach concerning the presence of these components in the male reproductive system. In testis, there is a high rate of protein synthesis, and the UPR mechanisms are well described. However, the presence of these mechanisms in spermatozoa, apparently transcriptionally inactive cells, is contentious, and it is unclear how sperm cells deal with stress. Here, we review current concepts and mechanisms of the UPR and highlight the relevance of these stress response pathways in male fertility, especially the presence and functional activation of those components in male germinal cells and spermatozoa.

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.

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.

Protein profiling in unlocking the basis of varicocele-associated infertility

Varicocele is one of the major causes of male infertility and has a negative impact on spermatogenesis. The conventional semen analysis does not reveal the underlying subcellular mechanisms associated with defects in spermatozoa. Proteomics and bioinformatics analysis can be used to identify the molecular aetiologies associated with poor semen quality in varicocele patients. Mitochondrial dysfunction has been identified as the main factor affecting normal physiological functions of spermatozoa. This article discusses the proteomic studies of spermatozoa and seminal plasma in varicocele patients. Proteomics can identify potential spermatozoa and seminal plasma biomarkers in varicocele-mediated male infertility. In future, these protein biomarkers can be useful in the development of noninvasive diagnostic and therapeutic strategies for varicocele patients.

Functional Analysis of Differentially Expressed Acetylated Spermatozoal Proteins in Infertile Men with Unilateral and Bilateral Varicocele

Sperm proteins undergo post-translational modifications, such as phosphorylation, acetylation, and ubiquitination, which in turn play a key role in determining their fertilizing ability. In the current study, we examined the sperm proteome of men with unilateral and bilateral varicocele to identify the key proteins affected by acetylation to gain an insight into the difference in the severity of affected sperm function in the latter. An LTQ-Orbitrap Elite hybrid mass spectrometer system was used to profile the sperm proteome in pooled unilateral and bilateral varicocele patients. Bioinformatics database and tools, such as UniProtKB, Ingenuity Pathway Analysis Software (IPA) and Metacore, were used to identify the differentially expressed proteins (DEPs) involved in the acetylation process. A total of 135 DEPs in the spermatozoa of unilateral and bilateral varicocele patients were found to be affected by acetylation. The majority of these DEPs found were regulated by key transcription factors such as androgen receptor, p53, and NRF2. Furthermore, the DEPs predicted to be affected by the acetylation process were associated with fertilization, acrosome reaction, mitochondrial dysfunction and oxidative stress. Aberrant expression of proteins and their differential acetylation process may affect the normal physiological functions of spermatozoa. Protein–protein interactions identified dysregulation of the proteasome complex in the bilateral varicocele group. Damage to the proteasome complex may result in aggregation of the misfolded proteins, which in turn increase sperm DNA damage and apoptosis in patients with bilateral varicocele.

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.

Sperm and Seminal Plasma Proteomics: Molecular Changes Associated with Varicocele-Mediated Male Infertility

Male infertility is a rising problem and the etiology at the molecular level is unclear. Use of omics has provided an insight into the underlying cellular changes in the spermatozoa of infertile men. Proteomics is one the promising omics techniques for biomarker screening that can provide complete information on molecular processes associated with male infertility. Varicocele is a pressing issue in the field of male infertility and the search for an appropriate diagnostic and therapeutic biomarker is still ongoing. In this review, we discuss the reports on proteomic profiles of sperm and seminal plasma in male infertility and provide an in-depth insight into varicocele studies associated with male infertility.

Iran's Contribution to Human Proteomic Research

Proteomics is a powerful approach to study the whole set of proteins expressed in an organism, organ, tissue or cell resulting in valuable information on physiological or pathological state of a biological system. High throughput proteomic data facilitated the understanding of various biological systems with respect to normal and pathological conditions particularly in the instances of human clinical manifestations. The important role of proteins as the functional gene products encouraged scientists to apply this technology to gain a better understanding of extremely complex biological systems. In last two decades, several proteomics teams have been gradually formed in Iran. In this review, we highlight the most important findings of proteomic research groups in Iran at various areas of stem cells, Y chromosome, infertility, infectious disease and biomarker discovery.

Protein Fingerprinting of Seminal Plasma Reveals Dysregulation of Exosome-Associated Proteins in Infertile Men with Unilateral Varicocele

Purpose

Aberrant expression of seminal plasma proteins are associated with altered homeostasis that may affect the fertilizing ability of spermatozoa. However, the precise roles of seminal exosomes on sperm function remain unclear. The objective of this study was to identify the differentially expressed proteins (DEPs) associated with varicocele-mediated infertility by comparing seminal plasma protein profile of unilateral varicocele patients with proven fertile donors.

Materials and Methods

Semen samples were obtained from 10 proven fertile donors with normal semen parameters and 33 infertile patients with unilateral varicocele. For proteomic analysis, 5 samples from each group were pooled and run in triplicate. Key DEPs (ANXA2, TF, CD63, KIF5B, SEMG1) associated with the exosome function were selected by bioinformatic tools and validated using Western blotting.

Results

A total of 47 seminal plasma proteins were differentially expressed in unilateral varicocele patients compared to fertile donors. Validation of exosome-associated DEPs in unilateral varicocele patients (n=7) and fertile donors (n=7) revealed significant upregulation of ANXA2 (p=0.0016) and downregulation of KIF5B (p=0.009). The main upstream regulators of the DEPs in seminal plasma of unilateral varicocele group were androgen receptor, YB1 and NRF2.

Conclusions

This is the first report to identify DEPs in seminal plasma of unilateral varicocele patients compared to fertile donors. Based on the detection of DEPs associated with exosomal function, Western blotting was used to validate the presence of defective exosome machinery in seminal plasma of unilateral varicocele patients. KIF5B and ANXA2 can be utilized as potential biomarkers of infertility in unilateral varicocele patients.

Varicocele management for infertility and pain: A systematic review

Despite being first described two thousand years ago, the varicocele remains a controversial multifaceted disease process with numerous biological consequences including infertility, hypogonadism, and chronic orchidalgia. The underlying mechanisms remain poorly understood and likely include hypoxia, oxidative stress, hyperthermia, anatomical aberrations, and genetics as primary components. Despite a high prevalence amongst asymptomatic fertile men, varicoceles paradoxically also represent the most common correctable cause for male infertility. In this systematic review we discuss the rich historical aspects of the varicocele and the contemporary data regarding its clinical manifestations. We performed a systematic literature review with the goal of comparing outcomes and complication rates of each of the major surgical approaches as they relate to infertility and pain. We performed a Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA)-compliant systematic literature review for manuscripts focused on varicocele and its biological consequences. We identified 112 studies suitable for qualitative analysis and included 56 of these for quantitative analysis, with an emphasis on infertility and chronic pain outcomes. Taken together, the clinical work to date suggests that the highest fertility rates and the lowest complication rates are associated with the microsurgical subinguinal surgical approach to varicocelectomy. In all, 26-40% of patients undergoing varicocelectomy will successfully achieve short-term spontaneous pregnancy, and up to 90% of all patients undergoing varicocelectomy for pain will have improvement and/or resolution of their symptoms. Taken together, the data support an ongoing role for varicocelectomy in both of these clinical arenas.

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.

Proteomic profile of seminal plasma in adolescents and adults with treated and untreated varicocele

Varicocele, the most important treatable cause of male infertility, is present in 15% of adult males, 35% of men with primary infertility, and 80% of men with secondary infertility. On the other hand, 80% of these men will not present infertility. Therefore, there is a need to differentiate a varicocele that is exerting a deleterious effect that is treatable from a “silent” varicocele. Despite the growing evidence of the cellular effects of varicocele, its underlying molecular mechanisms are still eluding. Proteomics has become a promising area to determine the reproductive biology of semen as well as to improve diagnosis of male infertility. This review aims to discuss the state-of-art in seminal plasma proteomics in patients with varicocele to discuss the challenges in undertaking these studies, as well as the future outlook derived from the growing body of evidence on the seminal proteome.

Proteomic signatures of infertile men with clinical varicocele and their validation studies reveal mitochondrial dysfunction leading to infertility

To study the major differences in the distribution of spermatozoa proteins in infertile men with varicocele by comparative proteomics and validation of their level of expression. The study-specific estimates for each varicocele outcome were combined to identify the proteins involved in varicocele-associated infertility in men irrespective of stage and laterality of their clinical varicocele. Expression levels of 5 key proteins (PKAR1A, AK7, CCT6B, HSPA2, and ODF2) involved in stress response and sperm function including molecular chaperones were validated by Western blotting. Ninety-nine proteins were differentially expressed in the varicocele group. Over 87% of the DEP involved in major energy metabolism and key sperm functions were underexpressed in the varicocele group. Key protein functions affected in the varicocele group were spermatogenesis, sperm motility, and mitochondrial dysfunction, which were further validated by Western blotting, corroborating the proteomics analysis. Varicocele is essentially a state of energy deprivation, hypoxia, and hyperthermia due to impaired blood supply, which is corroborated by down-regulation of lipid metabolism, mitochondrial electron transport chain, and Krebs cycle enzymes. To corroborate the proteomic analysis, expression of the 5 identified proteins of interest was validated by Western blotting. This study contributes toward establishing a biomarker “fingerprint” to assess sperm quality on the basis of molecular parameters.

Spermatozoa protein alterations in infertile men with bilateral varicocele

Among infertile men, a diagnosis of unilateral varicocele is made in 90% of varicocele cases and bilateral in the remaining varicocele cases. However, there are reports of under-diagnosis of bilateral varicocele among infertile men and that its prevalence is greater than 10%. In this prospective study, we aimed to examine the differentially expressed proteins (DEP) extracted from spermatozoa cells of patients with bilateral varicocele and fertile donors. Subjects consisted of 17 men diagnosed with bilateral varicocele and 10 proven fertile men as healthy controls. Using the LTQ-orbitrap elite hybrid mass spectrometry system, proteomic analysis was done on pooled samples from 3 patients with bilateral varicocele and 5 fertile men. From these samples, 73 DEP were identified of which 58 proteins were differentially expressed, with 7 proteins unique to the bilateral varicocele group and 8 proteins to the fertile control group. Majority of the DEPs were observed to be associated with metabolic processes, stress responses, oxidoreductase activity, enzyme regulation, and immune system processes. Seven DEP were involved in sperm function such as capacitation, motility, and sperm-zona binding. Proteins TEKT3 and TCP11 were validated by Western blot analysis and may serve as potential biomarkers for bilateral varicocele. In this study, we have demonstrated for the first time the presence of DEP and identified proteins with distinct reproductive functions which are altered in infertile men with bilateral varicocele. Functional proteomic profiling provides insight into the mechanistic implications of bilateral varicocele-associated male infertility.

Genome-wide association study for semen traits of the bulls in Chinese Holstein

A genome-wide association study (GWAS) was performed to identify markers and candidate genes for five semen traits in the Holstein bull population in China. The analyzed dataset consisted of records from 692 bulls from eight bull stations; each bull was genotyped using the Illumina BovineSNP50 BeadChip. Association tests between each trait and the 41 188 informative high-quality SNPs were achieved with gapit software. In total, 19 suggestive significant SNPs, partly located within the reported QTL regions or within or close to the reported candidate genes, associated with five semen traits were detected. By combining our GWAS results with the biological functions of these genes, eight novel promising candidate genes, including ETNK1, PDE3A, PDGFRB, CSF1R, WT1, DSCAML1, SOD1 and RUNX2, were identified that potentially relate to semen traits. Our findings may provide a basis for further research on the genetic mechanism of semen traits and marker-assisted selection of such traits in Holstein bulls.

Proteomic profile of seminal plasma in adolescents and adults with treated and untreated varicocele

Varicocele, the most important treatable cause of male infertility, is present in 15% of adult males, 35% of men with primary infertility, and 80% of men with secondary infertility. On the other hand, 80% of these men will not present infertility. Therefore, there is a need to differentiate a varicocele that is exerting a deleterious effect that is treatable from a "silent" varicocele. Despite the growing evidence of the cellular effects of varicocele, its underlying molecular mechanisms are still eluding. Proteomics has become a promising area to determine the reproductive biology of semen as well as to improve diagnosis of male infertility. This review aims to discuss the state-of-art in seminal plasma proteomics in patients with varicocele to discuss the challenges in undertaking these studies, as well as the future outlook derived from the growing body of evidence on the seminal proteome.

Major protein alterations in spermatozoa from infertile men with unilateral varicocele

BACKGROUND

The etiology of varicocele, a common cause of male factor infertility, remains unclear. Proteomic changes responsible for the underlying pathology of unilateral varicocele have not been evaluated. The objective of this prospective study was to employ proteomic techniques and bioinformatic tools to identify and analyze proteins of interest in infertile men with unilateral varicocele.

METHODS

Spermatozoa from infertile men with unilateral varicocele (n=5) and from fertile men (control; n=5) were pooled in two groups respectively. Proteins were extracted and separated by 1-D SDS-PAGE. Bands were digested and identified on a LTQ-Orbitrap Elite hybrid mass spectrometer system. Bioinformatic analysis identified the pathways and functions of the differentially expressed proteins (DEP).

RESULTS

Sperm concentration, motility and morphology were lower, and reactive oxygen species levels were higher in unilateral varicocele patients compared to healthy controls. The total number of proteins identified were 1055, 1010 and 1042 in the fertile group, and 795, 713 and 763 proteins in the unilateral varicocele group. Of the 369 DEP between both groups, 120 proteins were unique to the fertile group and 38 proteins were unique to the unilateral varicocele group. Compared to the control group, 114 proteins were overexpressed while 97 proteins were underexpressed in the unilateral varicocele group. We have identified 29 proteins of interest that are involved in spermatogenesis and other fundamental reproductive events such as sperm maturation, acquisition of sperm motility, hyperactivation, capacitation, acrosome reaction and fertilization. The major functional pathways of the 359 DEP related to the unilateral varicocele group involve metabolism, disease, immune system, gene expression, signal transduction and apoptosis. Functional annotations showed that unilateral varicocele mostly affected small molecule biochemistry and post-translational modification proteins. Proteins expressed uniquely in the unilateral varicocele group were cysteine-rich secretory protein 2 precursor (CRISP2) and arginase-2 (ARG2).

CONCLUSIONS

The expression of these proteins of interest are altered and possibly functionally compromised in infertile men with unilateral varicocele. If validated, these proteins may lead to potential biomarker(s) and help better understand the mechanism involved in the pathophysiology of unilateral varicocele in infertile men.

Ropporin gene expression in infertile asthenozoospermic men with varicocele before and after repair

OBJECTIVE

To assess Ropporin gene expression in the sperm of infertile asthenozoospermic men with varicocele (Vx) before and after repair.

METHODS

This study included 24 infertile asthenozoospermic men with Vx. They were subjected to history taking, clinical examination, scrotal color Doppler, and semen analysis with sperm separation. Three months after varicocelectomy, they were subjected to postoperative color Doppler, semen analysis, and sperm semiquantitative Reverse Transcription-Polymerase Chain Reaction assay for Ropporin gene expression levels.

RESULTS

Ropporin gene expression is significantly associated with different types of sperm motility, except for nonprogressive sperm motility. There was significant Ropporin gene overexpression postvaricocelectomy that was correlated with improved sperm count, sperm motility, and abnormal sperm morphology with decreased veins diameters.

CONCLUSION

Ropporin gene expression is related to the sperm motility. Its abnormal expression in the sperm of asthenozoospermic men with Vx is associated with impaired sperm motility that is improved after varicocelectomy.