Diagnostic approach to the infertile male patient

The Role of Environmental Toxicant-Induced Oxidative Stress in Male Infertility

Infertility is a serious public health issue affecting around 15% of couples globally. Of the 60-80 million people of reproductive age affected by infertility, 40-50% are due to male factor while 30-40% of cases are still idiopathic. The recent global deterioration in sperm quality raises apprehensions regarding the toxic effects of environmental pollutants on reproductive health of males. Environmental toxicants have shown strong evidences for inducing oxidative stress affecting spermatogenesis severely, thereby leading to reduced sperm motility, count, and DNA damage. Reactive oxygen species (ROS) influences the spermatozoa development and transit process both internally and externally. Low level of ROS is indispensable for critical physiological sperm processes like sperm capacitation, motility, acrosome reaction, hyper-activation, sperm-oocyte interaction, etc., while excessive ROS disrupt antioxidant molecules which is detrimental to normal functioning of the sperm. Hence, identification of potential environmental toxicant may have clinical relevance for early screening and diagnosis of male infertility.

Cementing the relationship between conventional and advanced semen parameters

Background

Affordable conventional semen analysis remains a fundamental procedure to be performed routinely during the diagnosis of male infertility. Advanced semen analyses provide valuable clinical insights in treatment-related decision-making, but these are highly expensive and lack universal standardization. This study aimed at determining the relationship between conventional semen parameters, measured with assistance of computer-aided sperm analysis (CASA), and a set of advanced semen tests. Basic semen analysis (n = 124) was performed according to the World Health Organization (WHO) guidelines. Sperm DNA fragmentation and intracellular superoxide (O2−•) levels were assessed by flow cytometry. Seminal plasma thiobarbituric acid reactive substances (TBARS) levels as well as superoxide dismutase (SOD) and catalase (CAT) activity were measured by spectrophotometry. Spearman’s rank correlation coefficient was used, with significance set at p < 0.05.

Results

Semen pH correlated negatively with TBARS (p < 0.01). The proportions of total and progressively motile as well as rapid spermatozoa correlated positively with CAT activity (p < 0.05). Sperm viability correlated negatively with both O2−• (p < 0.05) and DNA fragmentation (p = 0.01), while normal morphology correlated negatively with O2−• levels (p < 0.05) and positively with CAT activity (p < 0.05). Straight-line velocity (VCL) and average-path velocity (VAP) correlated negatively with both O2−• (p < 0.01) and TBARS (p < 0.01). Amplitude of lateral head displacement (ALH) correlated negatively with O2−• (p < 0.01) and DNA fragmentation (p < 0.01), while its correlation with SOD activity was positive (p < 0.05).

Conclusion

The results obtained from this study support the validity of some CASA parameters as sensitive indicators of changes in sperm oxidative status and DNA integrity. Predicting advanced from conventional parameters through the building of linear regression models should be considered for future studies.

Testicular ultrasound inhomogeneity is an informative parameter for fertility evaluation

Testicular volume (TV) is proposed to be a positive predictor of male fertility status, because of the relation known between the TV and the seminiferous tubule content. Independently of the measurement methodology, the role of TV and testicular ultrasound (US) assessments is still debated in andrological clinical practice. In this retrospective cohort study, we evaluated TV and testis US role in the diagnostic workup of andrological patients. All consecutive outpatients undergoing single-operator testis US (Modena, Italy) from March 2012 to March 2018 were enrolled, matching sonographic, hormonal, and seminal data. A total of 302 men were referred and evaluated for gynecomastia, suspected hypogonadism, couple infertility (CI), or sexual dysfunction. In the hypogonadal group, TV was lower compared to that in other groups (P < 0.001), and a significant, direct correlation between TV and testosterone level was observed in nonandrogen-treated patients (R = 0.911, P < 0.001), suggesting that testicular size could be related to the testosterone-secreting compartment. In the CI group, normozoospermic patients showed higher TV compared to men with impaired semen quality (P = 0.003) and azoospermia (P = 0.003). However, TV was not able to discriminate between patients presenting normal and altered semen quality. On the contrary, testis US inhomogeneity was more frequent in patients with impaired sperm quality (55.0%; P = 0.007) and azoospermia (40.0%; P = 0.012), compared to patients with normozoospermia (5%), identifying thereby the sonographic pattern as an informative parameter of the fertility status. Therefore, in the CI workup, US evaluation seems to be more informative than the TV assessment alone.

Testicular expression of TDRD1, TDRD5, TDRD9 and TDRD12 in azoospermia

Background

Tudor domain-containing proteins (TDRDs) play a critical role in piRNA biogenesis and germ cell development. piRNAs, small regulatory RNAs, act by silencing of transposons during germline development and it has recently been shown in animal model studies that defects in TDRD genes can lead to sterility in males.

Methods

Here we evaluate gene and protein expression levels of four key TDRDs (TDRD1, TDRD5, TDRD9 and TDRD12) in testicular biopsy samples obtained from men with obstructive azoospermia (OA, n = 29), as controls, and various types of non-obstructive azoospermia containing hypospermatogenesis (HP, 28), maturation arrest (MA, n = 30), and Sertoli cell-only syndrome (SCOS, n = 32) as cases. One-way ANOVA test followed by Dunnett’s multiple comparison post-test was used to determine inter-group differences in TDRD gene expression among cases and controls.

Results

The results showed very low expression of TDRD genes in SCOS specimens. Also, the expression of TDRD1 and TDRD9 genes were lower in MA samples compared to OA samples. The expression of TDRD5 significantly reduced in SCOS, MA and HP specimens than the OA specimens. Indeed, TDRD12 exhibited a very low expression in HP specimens in comparison to OA specimens. All these results were confirmed by Western blot technique.

Conclusion

TDRDs could be very important in male infertility, which should be express in certain stages of spermatogenesis.

Identifying Mechanisms of Endometriosis-Associated Reduced Fecundity in a Rat Model: Novel Insights toward Understanding Human Infertility

The existence of endometriosis has been known since at least the nineteenth century, yet the lack of understanding of causes of infertility and therefore inadequate treatment approaches in endometriosis creates a significant challenge in reproductive medicine. Women worldwide suffer not only pain and infertility but also economical, societal, and physiological burdens. Studies of reproductive events in women are difficult to conduct due to a host of confounding personal and environmental factors and ethically limited due to the very nature of working with reproductive tissues and cells, especially embryos. Animal models are a viable adjunct to study mechanisms causing human reproductive anomalies and infertility in endometriosis. This chapter discusses reproductive anomalies causing infertility in endometriosis and well-established animal models which help decipher the problems and lead to heretofore unknown nonsurgical, nonhormonal methods to manage endometriosis in women. In addition, studies of effects of developmental exposure to endometriosis are revealing for the first time, in both female and male offspring, transgenerational subfertility in a rat model providing insights into the familial nature of endometriosis and possible epigenetic involvement.

Antioxidants and Male Fertility: from Molecular Studies to Clinical Evidence

Spermatozoa are physiologically exposed to reactive oxygen species (ROS) that play a pivotal role on several sperm functions through activation of different intracellular mechanisms involved in physiological functions such as sperm capacitation associated-events. However, ROS overproduction depletes sperm antioxidant system, which leads to a condition of oxidative stress (OS). Subfertile and infertile men are known to present higher amount of ROS in the reproductive tract which causes sperm DNA damage and results in lower fertility and pregnancy rates. Thus, there is a growing number of couples seeking fertility treatment and assisted reproductive technologies (ART) due to OS-related problems in the male partner. Interestingly, although ART can be successfully used, it is also related with an increase in ROS production. This has led to a debate if antioxidants should be proposed as part of a fertility treatment in an attempt to decrease non-physiological elevated levels of ROS. However, the rationale behind oral antioxidants intake and positive effects on male reproduction outcome is only supported by few studies. In addition, it is unclear whether negative effects may arise from oral antioxidants intake. Although there are some contrasting reports, oral consumption of compounds with antioxidant activity appears to improve sperm parameters, such as motility and concentration, and decrease DNA damage, but there is not sufficient evidence that fertility rates and live birth really improve after antioxidants intake. Moreover, it depends on the type of antioxidants, treatment duration, and even the diagnostics of the man’s fertility, among other factors. Literature also suggests that the main advantage of antioxidant therapy is to extend sperm preservation to be used during ART. Herein, we discuss ROS production and its relevance in male fertility and antioxidant therapy with focus on molecular mechanisms and clinical evidence.

Evaluation of the Sysmex UF-1000i system as an alternative for the screening of genital tract inflammation in male infertility patients

The number of white blood cell (WBC) in semen is an important indicator of genital tract inflammation in male infertility. The peroxidase assay is the recommended reference method for seminal WBC counting. However, it is time-consuming and may cause relatively heavy workload in daily routine. Meanwhile, the main component in the reagent of peroxidase test is harmful to human and the environment. In this study, we evaluated the analytical performance of the Sysmex UF-1000i that is a urine flow cytometer as a screening tool for genital tract infection in male infertility patients through the counting of seminal WBC. We examined 143 semen samples and compared the results of UF-1000i and manual microscopy. The intra-assay variability, stability and linearity studies were performed. The intravariability (CV %) of seminal WBC count by Sysmex UF-1000i was 2.34%-9.65%. The method of UF-1000i displayed a good agreement with the reference assay of manual microscopy, and the r value for correlation of seminal WBC count between UF-1000i and manual microscopy was over 0.999 (p < 0.001). The Sysmex UF-1000i is capable of producing reliable seminal WBC count consistent with that obtained by manual microscopy. It is a suitable alternative to the manual microscopy, thus reduces the workload.

Association of serum testosterone levels and testicular volume in adult patients

A retrospective observational study was undertaken to gain new insight into the relationship between total testicular volume and levels of serum testosterone, luteinising hormone, follicle-stimulating hormone, prolactin and clinical variables. A total of 312 men with sexual dysfunction or infertility were divided into groups A and B (156 each) on the basis of basal plasma testosterone ≤5 nmol/L of ≥12 nmol/L respectively. Group A was subclassified in A₁ (primary hypogonadism) and A₂ (secondary hypogonadism). There were significant differences in total testicular volume between group A (15.33 ± 11.94 ml) and group B (36.74 ± 6.9; p < .001) and also between subgroup A₁ (11.07 ± 8.49 ml) and subgroup A₂ (23.62 ± 13.04 ml; p < .001). Only 13.5% of patients in group B had a total testicular volume <30 ml. Differences in all studied parameters were found between group A and group B. There were no variations when comparing age, body mass index and testosterone in groups A₁ and A₂ . The use of total testicular volume and body mass index together for predicting testosterone levels yields a sensitivity and specificity of 85.3% and 86.5% respectively. Logistic regression analysis, univariate and multivariate models, using the measurement of total testicular volume resulted in a high capacity to predict testosterone levels.

Functional features and protein network of human sperm-egg interaction

Elucidation of the sperm-egg interaction at the molecular level is one of the unresolved problems in sexual reproduction, and understanding the molecular mechanism is crucial in solving problems in infertility and failed in vitro fertilization (IVF). Many molecular interactions in the form of protein-protein interactions (PPIs) mediate the sperm-egg membrane interaction. Due to the complexity of the problem such as difficulties in analyzing in vivo membrane PPIs, many efforts have failed to comprehensively elucidate the fusion mechanism and the molecular interactions that mediate sperm-egg membrane fusion. The main purpose of this study was to reveal possible protein interactions and associated molecular function during sperm-egg interaction using a protein interaction network approach. Different databases have been used to construct the human sperm-egg interaction network. The constructed network revealed new interactions. These included CD151 and CD9 in human oocyte that interact with CD49 in sperm, and CD49 and ITGA4 in sperm that interact with CD63 and CD81, respectively, in the oocyte. These results showed that the different integrins in sperm may be involved in human sperm-egg interaction. It was also suggested that sperm ADAM2 plays a role as a protein candidate involved in sperm-egg membrane interaction by interacting with CD9 in the oocyte. Interleukin-4 receptor activity, receptor signaling protein tyrosine kinase activity, and manganese ion transmembrane transport activity are the major molecular functions in sperm-egg interaction protein network. The disease association analysis indicated that sperm-egg interaction defects are also reflected in other disease networks such as cardiovascular, hematological, and breast cancer diseases. By analyzing the network, we identified the major molecular functions and disease association genes in sperm-egg interaction protein. Further experimental studies will be required to confirm the significance of these new computationally resolved interactions and the genetic links between sperm-egg interaction abnormalities and the associated disease.

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.

Histopathologic patterns of testicular biopsies in infertile azoospermic men with varicocele

In azoospermic infertile men with varicocele, testicular biopsy revealed histopathologic patterns that varied from disorganized spermatogenesis with low or moderate sperm scores to early (primary spermatocytes stage) or late (spermatid stage) arrested spermatogenesis or germ cell aplasia and Sertoli cells only. Diagnostic testicular biopsy can be helpful for accurate management of azoospermic infertile men with varicoceles before surgical repair.