Evaluation of seminal plasma proteomics and relevance of FSH in identification of nonobstructive azoospermia: A preliminary study

Proteomic biomarkers in seminal plasma as predictors of reproductive potential in azoospermic men

Introduction

Azoospermia, characterized by an absence of sperm in the ejaculate, represents the most severe form of male infertility. While surgical sperm retrieval in obstructive azoospermia (OA) is successful in the majority of cases, patients with non-obstructive azoospermia (NOA) show retrieval rates of only about 50% and thus frequently have unnecessary surgery. Surgical intervention could be avoided if patients without preserved spermatogenesis are identified preoperatively. This prospective study aimed to discover biomarkers in seminal plasma that could be employed for a non-invasive differential diagnosis of OA/NOA in order to rationalize surgery recommendations and improve success rates.

Methods

All patients signed written informed consent, underwent comprehensive andrological evaluation, received human genetics to exclude relevant pathologies, and patients with azoospermia underwent surgical sperm retrieval. Using label-free LC-MS/MS, we compared the proteomes of seminal plasma samples from fertile men (healthy controls (HC), n=8) and infertile men diagnosed with 1) OA (n=7), 2) NOA with successful sperm retrieval (mixed testicular atrophy (MTA), n=8), and 3) NOA without sperm retrieval (Sertoli cell-only phenotype (SCO), n=7). Relative abundance changes of two candidate markers of sperm retrieval, HSPA2 and LDHC, were confirmed by Western Blot.

Results

We found the protein expression levels of 42 proteins to be significantly down-regulated (p ≤ 0.05) in seminal plasma from SCO NOA patients relative to HC whereas only one protein was down-regulated in seminal plasma from MTA patients. Analysis of tissue and cell expression suggested that the testis-specific proteins LDHC, PGK2, DPEP3, and germ-cell enriched heat-shock proteins HSPA2 and HSPA4L are promising biomarkers of spermatogenic function. Western blotting revealed a significantly lower abundance of LDHC and HSPA2 in the seminal plasma of men with NOA (SCO and MTA) compared to controls.

Discussion

The results indicate that certain testis-specific proteins when measured in seminal plasma, could serve as indicators of the presence of sperm in the testis and predict the success of sperm retrieval. Used in conjunction with conventional clinical assessments, these proteomic biomarkers may assist in the non-invasive diagnosis of idiopathic male infertility.

Proteomic approach towards identification of seminal fluid biomarkers from individuals with severe oligozoospermia, cryptozoospermia and non-obstructive azoospermia: a pilot study

Background

Infertility becomes a global problem that affects to the same extent females and males. As reasons of male infertility can differ among individuals, the accurate diagnostics is essential for effective treatment. The most problematic both in diagnostics and in treatment are disturbances of spermatogenesis. Seminal fluid is rich in proteins that potentially can serve as markers for male infertility and among them, markers of spermatogenesis which are highly desired.

Methods

To find biomarkers of spermatogenesis, we applied comparative proteomics using nano ultra performance liquid chromatography and tandem mass spectrometry (nanoUPLC-MS/MS) followed by single-sample Western blotting (WB) using seminal fluid samples from males with different types of infertility including non-obstructive azoospermia (NOA), cryptozoospermia (C) and severe oligozoospermia (SO). Then, the extensive survey on the identified proteins and their function in male reproductive system has been done.

Results

The proteomic approach has enabled to identified five seminal fluid proteins being potential markers of spermatogenesis disorders: ADGRG2, RAB3B, LTF, SLC2A3 and spermine synthase (SMS). Among them ADGRG2 seems to be strongly involved in male infertility. In addition, WB indicated that the distribution of LTF, SLC2A3 and SMS was not coherent among the individuals, especially in a group with NOA. Functional annotation analysis and search in proteomics databases revealed that vast majority of the proteins originated from extracellular environment.

Conclusions

The presented data point out several proteins that potentially can become biomarkers of male infertility. The data suggest, however, different mechanisms behind the male infertility indicating that the etiology is more complex. We assume that recognition of these mechanisms may lead to the creation of specific protein panel helpful in the management of male infertility and therefore, further studies are required.

Human umbilical cord mesenchymal stem cells (hUC-MSCs) alleviate paclitaxel-induced spermatogenesis defects and maintain male fertility

Chemotherapeutic drugs can cause reproductive damage by affecting sperm quality and other aspects of male fertility. Stem cells are thought to alleviate the damage caused by chemotherapy drugs and to play roles in reproductive protection and treatment. This study aimed to explore the effects of human umbilical cord mesenchymal stem cells (hUC-MSCs) on alleviating paclitaxel (PTX)-induced spermatogenesis and male fertility defects. An in vivo PTX-induced mice model was constructed to evaluate the reproductive toxicity and protective roles of hUC-MSCs in male fertility improvement. A 14 day PTX treatment regimen significantly attenuated mice spermatogenesis and sperm quality, including affecting spermatogenesis, reducing sperm counts, and decreasing sperm motility. hUC-MSCs treatment could significantly improve sperm functional indicators. Mating experiments with normal female mice and examination of embryo development at 7.5 days post-coitum (dpc) showed that hUC-MSCs restored male mouse fertility that was reduced by PTX. In IVF experiments, PTX impaired sperm fertility and blastocyst development, but hUC-MSCs treatment rescued these indicators. hUC-MSCs' protective role was also displayed through the increased expression of the fertility-related proteins HSPA2 and HSPA4L in testes with decreased expression in the PTX-treated group. These changes might be related to the PTX-induced decreases in expression of the germ cell proliferation protein PCNA and the meiosis proteins SYCP3, MLH1, and STRA8, which were restored after hUC-MSCs treatment. In the PTX-treated group, the expression of testicular antioxidant proteins SIRT1, NRF2, CAT, SOD1, and PRDX6 was significantly decreased, but hUC-MSCs could maintain these expressions and reverse PTX-related increases in BAX/BCL2 ratios. hUC-MSCs may be a promising agent with antioxidant and anti-apoptosis characteristics that can maintain sperm quality following chemotherapy treatment.

Proteomics of azoospermia: Towards the discovery of reliable markers for non-invasive diagnosis

PURPOSE

Azoospermia, as the most severe form of male infertility, no longer indicates sterility due to modern medical advancements. The current diagnostic procedure based on testicular biopsy has several drawbacks which urges the development of novel, non-invasive diagnostic procedures based on biomarkers. In the last two decades, there have been many proteomics studies investigating potential azoospermia biomarkers. In this review, we aimed to provide a critical evaluation of these studies.

EXPERIMENTAL DESIGN

Published articles were gathered by systematic literature search using Pubmed, Science Direct, and Google Scholar databases until March 2022 and were further preselected to include only studies on human samples.

RESULTS

A detailed review of these studies encompassed the proteomics platforms, sources of material, proposed candidate biomarkers, and their potential diagnostic specificity and sensitivity. In addition, emphasis was put on the top, most identified and validated biomarker candidates and their potential for discriminating azoospermia types and subtypes as well as predicting sperm retrieval success rate.

CONCLUSIONS

Proteomics research of azoospermia has laid the groundwork for the development of a more streamlined biomarker testing. The future research should be focused on well-designed studies including samples from all types/subtypes as well as further testing of the most promising biomarkers identified so far.

Evaluation of seminal plasma HSPA2 protein as a biomarker of human spermatogenesis status

In mammals, testicular Heat shock-related 70 kDa protein 2 (HSPA2) is a chaperon strictly linked to spermatogenesis status, whereas its presence in spermatozoa ensures successful oocyte fertilization. However, there is little information on this protein in seminal plasma in infertile males. Based on our previous two independent studies, we have selected HSPA2 to evaluate this seminal plasma protein is a potential biomarker of correct spermatogenesis. Using immunoblotting and mass spectrometry (MS) we have screened human seminal plasma samples for the presence of HSPA2. Samples were obtained from individuals with normozoospermia, cryptozoospermia, non-obstructive and obstructive azoospermia. Our results showed a lack of HSPA2 in seminal plasma in all azoospermic males however, in cryptozoospermia the results were extremely diversified. Additionally, the application of 2-dimensional gel electrophoresis (2-DE) indicated the presence of additional protein isoforms suggesting possible mechanisms underlying the male infertility. Our findings suggest seminal plasma HSPA2 protein as a possible biomarker not only of spermatogenesis status, especially in cryptozoospermic males, but also as a biomarker predicting the success of reproductive treatment including assisted reproductive techniques (ART).

Heat stress response of somatic cells in the testis

The testis is a temperature-sensitive organ that needs to be maintained 2-7 °C below core body temperature to ensure the production of normal sperm. Failure to maintain testicular temperature in mammals impairs spermatogenesis and leads to low sperm counts, poor sperm motility and abnormal sperm morphology in the ejaculate. This review discusses the recent knowledge on the response of testicular somatic cells to heat stress and, specifically, regarding the relevant contributions of heat, germ cell depletion and inflammatory reactions on the functions of Sertoli and Leydig cells. It also outlines mechanisms of testicular thermoregulation, as well as the thermogenic factors that impact testicular function.

Omics in Seminal Plasma: An Effective Strategy for Predicting Sperm Retrieval Outcome in Non-obstructive Azoospermia

Non-obstructive azoospermia (NOA) is a severe form of male factor infertility resulting from the impairment of sperm production. Surgical sperm retrieval followed by intracytoplasmic sperm injection (ICSI) is the only alternative for NOA patients to have their own genetic children. Nevertheless, due to an approximately 50% chance of success, harvesting sperm from these patients remains challenging. Thus, discovering noninvasive biomarkers, which are able to reliably predict the probability of sperm acquisition, not only can eliminate the risk of surgery but also can lower the costs of NOA diagnosis and treatment. Seminal plasma is the non-cellular and liquid portion of the ejaculate that consists of the secretions originating from testes and male accessory glands. In past years, a wide range of biomolecules including DNAs, RNAs, proteins, and metabolic intermediates have been identified by omics techniques in human seminal plasma. The current review aimed to briefly describe genomic, transcriptomic, proteomic, and metabolomic profiles of human seminal plasma in an attempt to introduce potential candidate noninvasive biomarkers for sperm-retrieval success in men with NOA.

Amniotic fluid-derived exosomes improved spermatogenesis in a rat model of azoospermia

AIMS

This study aimed to explore the therapeutic effects of amniotic fluid-derived extracellular vesicles including exosomes (AF-Exos) on the recovery of sperm production capacity in a rat model of azoospermia.

MAIN METHODS

The non-obstructive azoospermia (NOA) was induced in rats using intratesticular administration of Busulfan. Azoospermia was confirmed by testis histology. AF-Exos samples containing 10 or 40 μg exosomal proteins were injected into testicular tissue of NOA rats. After two months, the recovery of spermatogenesis was monitored via histopathological staining, spermiogram, and hormonal analysis. Immunohistochemistry staining for OCT-3/4 was used to identify of spermatogonial progenitors. The expression of DAZL and VASA, was also measured.

KEY FINDINGS

AF-Exos exhibited sphere-shaped morphology with the mean diameter and zeta potential of 50 ± 7.521 nm and -7.16 mV. Immunoblots revealed that isolated nanoparticles were CD63, CD9, and CD81 positive. Histopathological evaluation revealed that spermatogenesis was improved significantly in NOA rats after AF-Exos injection. Data showed that the sperm parameters and spermatogenesis index were significantly improved after AF-Exos injection compared to azoospermic groups. OCT-3/4⁺ cells were increased in NOA rats after AF-Exos injection, showing the restoration of spermatogenesis. In the present study, both doses of exosome (10 and 40 μg) restored the testicular function of NOA rats. DAZL and VASA were increased significantly in animals who received 40 μg exosomal protein compared to azoospermic rats. Except in a high dose of AF-Exos (40 μg) for Testosterone and FSH, no statistically significant differences were found regarding hormones post-exosome injection.

SIGNIFICANCE

Our study demonstrated that AF-Exos regenerated spermatogenesis and improved sperm quality in NOA rats.

Alterations in seminal plasma proteomic profile in men with primary and secondary infertility

Proteome of seminal plasma provides profound information related to the male reproductive health. This pilot study was conducted to characterize proteomic profile of seminal plasma from men with primary, or secondary infertility and compare it with proven fertile men. Study participants (n = 59) were recruited at the Cleveland Clinic and divided according to their fertility status: proven fertile (n = 39); primary infertility (n = 11) and secondary infertility (n = 9). Proteomic shotgun analysis revealed a total of 515 peptides common to primary infertility and control group; whereas 523 peptides were common to secondary infertility and control group. Bioinformatic analysis revealed dysregulation of biological processes such as cell secretion and vesicle mediated transport in primary infertility, whereas immune system response, regulation of proteolysis and iron homeostasis were dysregulated in secondary infertility. Western blot validation showed overexpression of ANXA2 and CDC42, and underexpression of SEMG2 proteins in primary infertility; and overexpression of ANXA2 and APP proteins in secondary infertility. This study elucidates the potential role of differentially expressed proteins in the seminal plasma as diagnostic biomarker for primary and secondary infertility. Furthermore, our results suggest maturation failure and immune reaction response as the main cause of infertility in men with primary and secondary infertility, respectively. Additional validation of the proteins involved in the above pathways is warranted.

Evaluation of the antioxidative enzymes in the seminal plasma of infertile men: Contribution to classic semen quality analysis

Protein expression/activity of antioxidative defense enzymes (AD) in seminal plasma of fertile men might be used as biomarkers of male fertility status. To test this concept, the present study examined the semen parameters of males among 14 normal idiopathic (normozoospermia) and 84 subnormal (teratozoospermia, oligoteratozoospermia, oligoasthenoteratozoospermia) infertile individuals\. We investigated levels of protein expression/activity of Cu, Zn superoxide dismutase (CuZnSOD), manganese superoxide dismutase (MnSOD), catalase and glutathione peroxidase (GSH-Px), their association with functional sperm parameters, as well as their potential to serve as biomarkers of specific sperm pathologies. Although the activity of CuZnSOD and protein expression of catalase were significantly correlated with several sperm parameters, underlying their potential role in etiology of various sperm abnormalities, investigation of their potential usefulness as a biomarker of semen quality showed that these AD enzymes could not distinguish subtle differences between various sperm pathologies. In contrast, GSH-Px activity was decreased in all groups with sperm pathologies and was a very good indicator of aberrations in functional sperm parameters, explaining up to 94.6% of infertility cases where functional sperm parameters were affected. Therefore, assessment of GSH-Px activity showed the potential to discriminate between infertile males with normal and subnormal semen characteristics and may prove useful in the evaluation of male (in)fertility. Abbreviations: AD: antioxidative defense; Cu, Zn SOD: copper, zinc superoxide dismutase; GSH-Px: glutathione peroxidase; MnSOD: manganese superoxide dismutase; NS: normospermia; OATS: oligoasthenoteratozoospermia; OTS: oligoteratozoospermia; ROC: receiver operating characteristic; ROS: reactive oxygen species; TS: teratozoospermia; WHO: world health organization.

Proteomic Profiling of Seminal Plasma Proteins in Varicocele Patients

Purpose

Seminal plasma provides a nutritive and protective milieu for spermatozoa. It contains factors/proteins required for sperm maturation, hyperactivation, capacitation and acrosome reaction. Alteration in the expression levels of seminal plasma proteins affect the fertilization process. The main objective of this study is to compare the seminal plasma proteome of healthy fertile men (control group) with varicocele patients in order to identify the differentially expressed seminal plasma proteins.

Materials and Methods

Pooled seminal plasma samples from control (n=5) and varicocele (unilateral: n=5 and bilateral: n=5) subjects were used for proteomic profiling and functional bioinformatic analysis. Key differentially expressed proteins (DEPs) associated with binding of zona pellucida (acrosin; ACR), protein folding (heat shock related 70 kDa protein 2; HSPA2), oxidative stress (peroxiredoxin 2; PRDX2), lipid peroxidation and DNA fragmentation (apolipoprotein A2; APOA2) were validated by Western blot. Statistical analysis was conducted using Mann-Whitney test.

Results

A total of 412 and 486 proteins were detected in seminal plasma of control group and varicocele patients respectively. Twenty-eight proteins were identified as DEPs between varicocele and control group. Validation of DEPs revealed downregulation of HSPA2 (p=0.0037) as well as APOA2 (p=0.0373), and upregulation of PRDX2 (p=0.0474).

Conclusions

The seminal plasma protein profile of varicocele patients differ from healthy fertile men. Aberrant expression of seminal plasma proteins serve as an indicator of sperm pathology in varicocele patients.