Clinical Laboratory Evaluation of Male Subfertility

Environmental and occupational factors and higher risk of couple infertility: a systematic review study

Background

Infertility is a global health problem that represents an increasing trend due to new lifestyles following technological advances since individuals are facing more risk factors than before. The present systematic review study aimed to investigate the impact of environmental and occupational factors on reproductive parameters and increased risk of couple infertility.

Main body

Scopus, PubMed, SID, and Web of Science databases were searched for the available observational (i.e., cohort, case-control, and cross-sectional) systematic review, meta-analysis, and clinical trial studies between 2007 and 2019. To this end, keywords such as ‘Environmental exposure’, ‘Occupational exposure’, ‘Environmental pollutants’, ‘Environmental pollution’, ‘Couple infertility’, ‘Sterility’, and ‘Sub-fertility’ were used. The retrieved investigations examined the impact of environmental and occupational risk factors on reproductive indices and increased infertility risk. Totally, 66 out of 9519 papers were evaluated after considering the inclusion and exclusion criteria. The reported risk factors in the reviewed studies were heavy metals, cigarette smoking, and exposure to chemicals through consumer goods, urban life, and proximity to main roads. In addition, occupational factors included heavy physical activity, prolonged sitting, exposure to a hot environment, contact with formaldehyde, pesticides, insecticides, mechanical vibration, and contact with ionizing radiation, all of which affected the reproductive parameters. However, some researchers found no significant associations in this regard.

Short conclusion

In general, individuals with known impairments in reproductive parameters were more exposed to risk factors. Nonetheless, more studies are needed to determine the risk of infertility in the population.

Effects of high-fat diet and treadmill running on the hypothalamic Kiss-1-GPR54 signaling pathway in male growing rats

BACKGROUND

Kiss-1 neuron, one of the metabolic sensors in the hypothalamus, is necessary for puberty initiation. It acts through G protein-coupled receptor, known as GPR54. In this study, the mechanism of the hypothalamic Kiss-1-GPR54 signaling pathway in a high-fat diet and exercise was investigated in growing male rats.

METHODS

A total of 135 3-week-old male weaned rats were kept on a high-fat diet (HFD) and exercise (60-70% [Formula: see text], 1 h/day, 5 days/week). They were randomly divided, as follows: control group (C); normal diet + exercise group (CE); HFD group (H); and HFD + exercise group (HE). Hypothalamus, testis, and serum samples of each group were collected on postnatal day (PND) 21 (early childhood), 43 (puberty), and 56 (maturity). Immunofluorescence, quantitative real-time PCR, hematoxylin and eosin staining, and chemiluminescent immunoassays were used in the study. ANOVA was used to analyze the effects of age (PNDs 21, 43, and 56), exercise (exercise and sedentariness), and diet (high-fat and normal) on the biological indices of rats.

RESULTS

mRNA and protein expression of Kiss-1 and GPR54 in the hypothalamus gradually increased along with growth and peaked at PND 43, while those in serum testosterone increased and peaked at PND 56. The high-fat diet increased the expression of the Kiss-1-GPR54 system in the hypothalamus, whereas the serum testosterone decreased during different stages of growth. Exercise decreased the expression of Kiss-1 at PND 56 and increased it at PND 43. Meanwhile, it decreased testosterone and the deposition of lipid droplets in the testis at all ages of development.

CONCLUSIONS

The expression of Kiss-1-GPR54 in male rats showed fluctuating changes during growth and development. The high-fat diet was able to upregulate the expression of the Kiss-1-GPR54 system in the hypothalamus. The exercise was able to correct the adverse effect of the high-fat diet on the Kiss-1-GPR54 signaling pathway in the hypothalamus and the function of the hypothalamic-pituitary-gonadal (HPG) axis, but had age-specific effects on the male rats' development.

The multiple roles of RAB GTPases in female and male meiosis

BACKGROUND

RAB GTPases constitute the largest family of small GTPases and are found in all eukaryotes. RAB GTPases regulate components of the endomembrane system, the nucleus and the plasma membrane, and are involved in intracellular actin/tubulin-dependent vesicle movement, membrane fusion and cell growth in mitosis.

OBJECTIVE AND RATIONALE

RAB GTPases play multiple critical roles during both female and male meiosis. This review summarizes the progress made in our understanding of the role of RAB GTPases in female and male meiosis in different species. We also discuss the potential relationship between RAB GTPases and oocyte/sperm quality, which may help in understanding the mechanisms underlying oogenesis and spermatogenesis and potential genetic causes of infertility.

SEARCH METHODS

The PubMed database was searched for articles published between 1991 and 2020 using the following terms: 'RAB', 'RAB oocyte', 'RAB sperm' and 'RAB meiosis'.

OUTCOMES

An analysis of 126 relevant articles indicated that RAB GTPases are present in all eukaryotes, and ten subfamilies (almost 70 members) are expressed in human cells. The roles of 25 RAB proteins and orthologues in female meiosis and 12 in male meiosis have been reported. RAB proteins are essential for the accurate continuity of genetic material, successful fertilization and the normal growth of offspring. Distinct and crucial functions of RAB GTPases in meiosis have been reported. In oocytes, RAB GTPases are involved in spindle organization, kinetochore-microtubule attachment, chromosome alignment, actin filament-mediated spindle migration, cytokinesis, cell cycle and oocyte-embryo transition. RAB GTPases function in mitochondrial processes and Golgi-mediated vesicular transport during female meiosis, and are critical for cortical granule transport during fertilization and oocyte-embryo transition. In sperm, RAB GTPases are vital for cytoskeletal organization and successful cytokinesis, and are associated with Golgi-mediated acrosome formation, membrane trafficking and morphological changes of sperm cells, as well as the exocytosis-related acrosome reaction and zona reaction during fertilization.

WIDER IMPLICATIONS

Abnormal expression of RAB GTPases disrupts intracellular systems, which may induce diverse diseases. The roles of RAB proteins in female and male reproductive systems, thus, need to be considered. The mechanisms underlying the function of RAB GTPases and the binding specificity of their effectors during oogenesis, spermatogenesis and fertilization remain to be studied. This review should contribute to our understanding of the molecular mechanisms of oogenesis and spermatogenesis and potential genetic causes of infertility.

ICSI Versus Conventional IVF in Women Aged 40 Years or More and Unexplained Infertility: A Retrospective Evaluation of 685 Cycles with Propensity Score Model

This study compared the cumulative live birth rates following Intracytoplasmic sperm injection (ICSI) versus conventional in vitro fertilization (cIVF) in women aged 40 years or more and unexplained infertility. A cohort of 685 women undergoing either autologous conventional IVF or ICSI was retrospectively analyzed. The effects of conventional IVF or ICSI procedure on cumulative pregnancy and live birth rates were evaluated in univariate and in multivariable analysis. In order to reduce potential differences between women undergoing either IVF or ICSI and to obtain unbiased estimation of the treatment effect, propensity score was estimated. ICSI was performed in 307 couples (ICSI group), whereas cIVF was performed in 297 couples (cIVF group), resulting in 45 and 43 live deliveries, respectively. No differences were observed in morphological embryo quality, in the number of cleavage stage embryos, in the number of transferred embryos, and in the number of vitrified embryos. As for the clinical outcome, no differences were observed in pregnancy rate, cumulative pregnancy rate, live birth rate, cumulative live birth rate, and abortion rate. The present results suggest that ICSI is not associated with increased likelihood of a live birth for unexplained, non-male factor infertility, in women aged 40 years or more.

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.

Uncertainty of measurement and clinical value of semen analysis: has standardisation through professional guidelines helped or hindered progress?

This article suggests that diagnostic semen analysis has no more clinical value today than it had 25-30 years ago, and both the confusion surrounding its evidence base (in terms of relationship with conception) and the low level of confidence in the clinical setting is attributable to an associated high level of 'uncertainty'. Consideration of the concept of measurement uncertainty is mandatory for medical laboratories applying for the ISO15189 standard. It is evident that the entire semen analysis process is prone to error every step from specimen collection to the reporting of results and serves to compound uncertainty associated with diagnosis or prognosis. Perceived adherence to published guidelines for the assessment of sperm concentration, motility and morphology does not guarantee a reliable and reproducible test result. Moreover, the high level of uncertainty associated with manual sperm motility and morphology can be attributed to subjectivity and lack a traceable standard. This article describes where and why uncertainty exists and suggests that semen analysis will continue to be of limited value until it is more adequately considered and addressed. Although professional guidelines for good practice have provided the foundations for testing procedures for many years, the risk in following rather prescriptive guidance to the letter is that unless they are based on an overwhelmingly firm evidence base, the quality of semen analysis will remain poor and the progress towards the development of more innovative methods for investigating male infertility will be slow.

Measuring Sperm DNA Fragmentation and Clinical Outcomes of Medically Assisted Reproduction: A Systematic Review and Meta-Analysis

Sperm DNA fragmentation has been associated with reduced fertilization rates, embryo quality, pregnancy rates and increased miscarriage rates. Various methods exist to test sperm DNA fragmentation such as the sperm chromatin structure assay (SCSA), the sperm chromatin dispersion (SCD) test, the terminal deoxynucleotidyl transferase mediated deoxyuridine triphosphate nick end labelling (TUNEL) assay and the single cell gel electrophoresis (Comet) assay. We performed a systematic review and meta-analysis to assess the value of measuring sperm DNA fragmentation in predicting chance of ongoing pregnancy with IVF or ICSI. Out of 658 unique studies, 30 had extractable data and were thus included in the meta-analysis. Overall, the sperm DNA fragmentation tests had a reasonable to good sensitivity. A wide variety of other factors may also affect the IVF/ICSI outcome, reflected by limited to very low specificity. The constructed hierarchical summary receiver operating characteristic (HSROC) curve indicated a fair discriminatory capacity of the TUNEL assay (area under the curve (AUC) of 0.71; 95% CI 0.66 to 0.74) and Comet assay (AUC of 0.73; 95% CI 0.19 to 0.97). The SCSA and the SCD test had poor predictive capacity. Importantly, for the TUNEL assay, SCD test and Comet assay, meta-regression showed no differences in predictive value between IVF and ICSI. For the SCSA meta-regression indicated the predictive values for IVF and ICSI were different. The present review suggests that current sperm DNA fragmentation tests have limited capacity to predict the chance of pregnancy in the context of MAR. Furthermore, sperm DNA fragmentation tests have little or no difference in predictive value between IVF and ICSI. At this moment, there is insufficient evidence to recommend the routine use of sperm DNA fragmentation tests in couples undergoing MAR both for the prediction of pregnancy and for the choice of treatment. Given the significant limitations of the evidence and the methodological weakness and design of the included studies, we do urge for further research on the predictive value of sperm DNA fragmentation for the chance of pregnancy after MAR, also in comparison with other predictors of pregnancy after MAR.

Effects of Synthetic Serum Supplementation in Sperm Preparation Media on Sperm Capacitation and Function Test Results

Albumin supplementation of culture media induces sperm capacitation in assisted reproduction technique cycles. Synthetic serum supplementation is clinically used to replace albumin for preventing transmission of infectious agents. However, the effects of synthetic serum supplementation on sperm capacitation have rarely been investigated. Spermatozoa from 30 men with normal basic semen analysis results were collected, divided into five aliquots, and cultured in capacitating conditions in four combinations of two synthetic serum supplements, serum substitute supplement (SSS) and serum protein substitute (SPS), and two fertilization media, Quinns Advantage™ Fertilization (QF) and human tubular fluid (HTF) media. Reactive oxygen species (ROS) levels in spermatozoa were measured through chemiluminescence. Furthermore, acrosome reaction and western blotting for tyrosine phosphorylation were used to evaluate sperm capacitation. HTF+SSS had significantly higher ROS levels than QF+SPS did (11,725 ± 1,172 versus 6,278 ± 864 relative light units). In addition, the spermatozoa cultured in QF+SPS had lower motility, acrosome reaction rates, and tyrosine phosphorylation levels compared with those cultured in HTF+SSS. In conclusion, the effects of synthetic serum supplementation on sperm capacitation varied according to the combination of media. These differences may lead to variations in spermatozoon ROS levels, thus affecting sperm function test results.

Unexplained male infertility: diagnosis and management

Unexplained male infertility is a diagnosis reserved for men in whom routine semen analyses results are within normal values and physical as well as endocrine abnormalities were ruled out. In addition to erectile problems and coital factors, immunologic causes and sperm dysfunction may contribute to such condition. New etiologies of unexplained male infertility include low level leukocytospermia and mitochondrial DNA polymerase gene polymorphism. Contemporary andrology may reveal cellular and sub-cellular sperm dysfunctions which may explain subfertility in such cases, thus aiding the clinician to direct the further work-up, diagnosis and counseling of the infertile male. The objective of this article is to highlight the concept of unexplained male infertility and focuses on the diagnosis and treatment of this condition in the era of modern andrology and assisted reproductive techniques. Extensive literature review was performed using the search engines: Pubmed, Science-direct, Ovid and Scopus.

European Association of Urology guidelines on Male Infertility: the 2012 update

CONTEXT

New data regarding the diagnosis and treatment of male infertility have emerged and led to an update of the European Association of Urology (EAU) guidelines for Male Infertility.

OBJECTIVE

To review the new EAU guidelines for Male Infertility.

EVIDENCE ACQUISITION

A comprehensive work-up of the literature obtained from Medline, the Cochrane Central Register of Systematic Reviews, and reference lists in publications and review articles was developed and screened by a group of urologists and andrologists appointed by the EAU Guidelines Committee. Previous recommendations based on the older literature on this subject were taken into account. Levels of evidence and grade of guideline recommendations were added, modified from the Oxford Centre for Evidence-based Medicine Levels of Evidence.

EVIDENCE SUMMARY

These EAU guidelines are a short comprehensive overview of the updated guidelines of male infertility as recently published by the EAU (http://www.uroweb.org/guidelines/online-guidelines/), and they are also available in the National Guideline Clearinghouse (http://www.guideline.gov/).

Sperm DNA integrity assays: diagnostic and prognostic challenges and implications in management of infertility

Sperm is not a simple carrier of paternal genetic information but its role extends clearly beyond fertilization. Integrity of sperm genome is an essential pre-requisite for birth of healthy offspring and evaluation of sperm should entail DNA integrity analysis. DNA integrity analysis is a better diagnostic and prognostic marker of sperm reproductive potential. Conventional semen analysis emphasizes on sperm concentration, viability, motility and morphology and has been proven to be a poor indicator of reproductive potential and pregnancy outcome. To overcome the drawbacks associated with conventional semen analysis more useful fertility tests and molecular biomarkers have been explored. Among the different tests which have evolved for assessing the sperm reproductive potential, tests for sperm DNA quality are most promising. Sperm DNA damage has been closely associated with numerous indicators of reproductive health including fertilization, embryo quality, implantation, spontaneous abortion, congenital malformations and childhood diseases. It therefore has great potential as a prognostic test for both in vitro and in vivo conception. This review presents an updated account of tests that have better diagnostic and prognostic implications in the evaluation of sperm DNA damage. The basic principles, outline of methodology, advantage, disadvantage, clinical significance of each technique and implications of these tests have been discussed. The logistics of each test with respect to available resources and equipment in an andrology laboratory, the feasibility of performing these tests in routine diagnostic workup of infertile men and the opportunities and challenges provided by DNA testing in male fertility determination are also presented.

The role of hyaluronic acid binding assay in choosing the fertilization method for patients undergoing IVF for unexplained infertility

PURPOSE

Patients with unexplained infertility may have fertilization problems. Split fertilization (ICSI and conventional IVF on sibling oocytes) is often used to avoid poor fertilization. Our aim was to assess the ability of hyaluronic acid binding (HA-binding) assay to predict spontaneous fertilization during IVF.

METHODS

Prospective, blinded, controlled trial. Patients undergoing their first IVF cycle for unexplained infertility were eligible. Split fertilization was used. IVF and ICSI fertilization rates and embryo development based on 3 HA-binding cut-offs (< 60%; 60-80%; >80%) were compared.

RESULTS

ICSI fertilization was higher than IVF, but none of the HA-binding cut-off levels predicted those cases where IVF was less effective, therefore ICSI only would have lead to improved outcome. Embryo development and morphology were similar in all cut-off groups.

CONCLUSIONS

HA-binding did not predict spontaneous fertilization in patients with unexplained infertility undergoing IVF treatment. When it was used for "screening" it did not help to select the method of fertilization.

High throughput, parallel imaging and biomarker quantification of human spermatozoa by ImageStream flow cytometry

Spermatid specific thioredoxin-3 protein (SPTRX-3) accumulates in the superfluous cytoplasm of defective human spermatozoa. Novel ImageStream technology combining flow cytometry with cell imaging was used for parallel quantification and visualization of SPTRX-3 protein in defective spermatozoa of five men from infertile couples. The majority of the SPTRX-3 containing cells were overwhelmingly spermatozoa with a variety of morphological defects, detectable in the ImageStream recorded images. Quantitative parameters of relative SPTRX-3 induced fluorescence measured by ImageStream correlated closely with conventional flow cytometric measurements of the same sample set and reflected the results of clinical semen evaluation. Image Stream quantification of SPTRX-3 combines and surpasses the informative value of both conventional flow cytometry and light microscopic semen evaluation. The observed patterns of the retention of SPTRX-3 in the sperm samples from infertility patients support the view that SPTRX3 is a biomarker of male infertility.

The transcriptome of spermatozoa used in homologous intrauterine insemination varies considerably between samples that achieve pregnancy and those that do not

OBJECTIVE

To differentiate transcripts' expression in the sperm from patients who achieved pregnancy in their first IUI cycle from those who did not. Basic sperm analysis is limited to forecasting pregnancies by means of assisted reproduction. New assays, such as microarray analysis, are potential predictive tools for this purpose.

DESIGN

Nested case-control study.

SETTING

University-affiliated private setting.

PATIENT(S)

Twenty sperm samples were obtained from infertile males undergoing their first IUI cycle with healthy partners. Sperm samples with which pregnancy was achieved (P; n=10) and those with which it was not achieved (NP; n=10) were identified and their respective messenger RNA expression profiles were compared.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Using microarrays, global genome expression was compared in pooled samples from each group. Results were evaluated to detect differentially expressed transcripts (TDEs; FC>2; P<0.05) and to identify those transcripts that were expressed in only one of the groups (exclusive transcripts [ETs]).

RESULT(S)

In group P, 756 TDEs presented increased expression, whereas 194 in group NP were found to be overexpressed. Furthermore, we found 741 ETs that were expressed only in group P and 976 that were expressed only in group NP.

CONCLUSION(S)

Results reveal profound differences between expression profiles of sperm samples that impregnate successfully and those that do not. These differences might improve the predictive power of sperm evaluation to estimate IUI success by complementing the basic sperm analysis.

Abnormally high body mass index and tobacco use are associated with poor sperm quality as revealed by reduced sperm binding to hyaluronan-coated slides

Responses on a lifestyle questionnaire were correlated with results from traditional semen analysis and a newer functional sperm assay, namely, the ability of sperm to bind to a hyaluronan-coated slide. Increased percent normal morphology and motile sperm concentration were positively correlated with increased HA-binding score, whereas tobacco use (either current or previous history) and abnormally high body mass index were associated with lower binding scores.

Sperm chromatin: fertile grounds for proteomic discovery of clinical tools

Sperm are remarkably complex cells with a singularly important mission: to deliver paternal DNA and its associated factors to the oocyte to start a new life. The integrity of sperm DNA is a keystone of reproductive success, which includes fertilization and embryonic development. In addition, the significance in these processes of proteins that associate with sperm DNA is increasingly being appreciated. In this review, we highlight proteomic studies that have identified sperm chromatin proteins with fertility roles that have been validated by molecular studies in model organisms or correlations in the clinic. Up to 50% of male-factor infertility cases in the clinic have no known cause and therefore no direct treatment. In-depth study of the molecular basis of infertility has great potential to inform the development of sensitive diagnostic tools and effective therapies that will address this incongruity. Because sperm rely on testis-specific protein isoforms and post-translational modifications for their development and function, sperm-specific processes are ideal for proteomic explorations that can bridge the research lab and fertility clinic.

[Assessing sperm DNA damage]

Infertility affects almost 20% of couples in reproductive age and the male factor being responsible of 50% of this infertility. Among the classic parameters that determine a good seminal quality such as sperm motility, sperm morphology or the quality of the of acrosomes and/or sperm membranes, the integrity of the DNA molecule is crucial to carry out a successful fertilization. Nevertheless, the study of this parameter has not been straightforward approached. This fact has shunned its incorporation, as a routine technique, within a standard seminogram. The aim of the present review is to summarize and update those technologies that are considered more successful to study sperm DNA fragmentation with special emphasis to: 1) the levels of technological complexity and the possibility of its use in laboratories of andrology, according with the equipment and the resources available, and 2) the effects and possible implications of high level of sperm DNA fragmentation for fecundation, embryo development and fertility.

The importance of diagnosis in the clinical management of infertility in the male

This paper examines the importance of a clinical diagnosis in the management of infertility in the male and discusses the reasons for this statement. The treatment of male infertility is now often carried out solely by gynaecologists. These specialists have frequently had little training in the examination of the male genital tract nor have they had any teaching in either urology or in the pathology of the lower genito-urinary tract. The routine application of IVF may be a consequence of these failings and should this form of treatment be shown to have been unnecessary or, especially, should it result in a clinical disaster, then a serious medico-legal problem may result. The degree of training that is given to the gynaecologist working in this field is also examined and suggestions are made as to how this could be improved.