The impact of antisperm antibodies on human male reproductive function: an update

Anti-sperm Antibodies as an Increasing Threat to Male Fertility: Immunological Insights, Diagnostic and Therapeutic Strategies

It is a fact that sperm possess antigenic properties. Substantial scientific research suggests that specific antibodies that attach to sperm antigens can induce infertility in both humans and other species. Antisperm antibodies (ASA) represent a significant etiology of infertility in humans, leading to immunoinfertility. The association between ASA and infertility is multifaceted. The observation of sperm agglutination, although not conclusive for the diagnosis of immunological infertility, may suggest the presence of ASA. Nevertheless, ASA may also manifest in the lack of any sperm agglutination. Managing ASA from an andrological perspective depends on the underlying cause and the specific approaches healthcare professionals adopt. The precise etiology of male infertility resulting from ASA remains unclear. Current research has examined the impact of ASA and its prevalence among infertile males to understand the relationship between ASA and changes in semen parameters. However, the findings have been inconclusive. Numerous techniques have been documented for the management of immunoinfertility. This review examines the importance of ASA in the context of infertility, encompassing the postulated mechanisms underlying the development of ASA, the various assays employed for detecting them, and the available treatments.

Effects of antisperm antibodies post vasectomy reversal on pregnancy rates

OBJECTIVE

To investigate the correlation between antisperm antibodies (ASAs), pregnancy rates, and the method of conception following vasectomy reversal. This is particularly relevant as patients undergoing vasectomy reversal often express concerns about the potential inhibitory effects of ASAs on achieving pregnancy. Additionally, the American Urological Association guidelines for vasectomy emphasize the need for further research to address this question.

PATIENT AND METHODS

We conducted a retrospective analysis involving chart reviews and phone interviews with individuals who underwent vasectomy reversal at our institution between May 2015 and April 2023. Patients who underwent vasectomy reversal for reasons other than fertility, as well as those lacking postoperative semen analysis with ASA data, were excluded. We classified patients based on low (below 50%) or high (50% or above) ASA levels determined by their initial postoperative semen analysis. The primary outcome measured was the pregnancy rate, including details on the method of conception.

RESULTS

A total of 145 patients were subjected to chart review. The median age at the time of surgery was 43 years, with a median obstruction interval of 7.7 years. The median age of their partners was 29 years. The majority (80%) of patients underwent bilateral vasovasostomy. Among them, 60 patients (41.4%) exhibited low (< 50%) ASA levels, while 85 (58.6%) had high (≥ 50%) ASA levels. Follow-up phone interviews were completed by 48 patients. Among them, the 19 men with low ASA levels, 13 (68.4%) achieved pregnancy, with 6 (31.6%) experiencing spontaneous conception. For the 29 men with high ASA levels, 21 (72.4%) achieved pregnancy, including 11 (38%) through spontaneous conception. The p-value from Fisher's exact test was 0.2.

CONCLUSIONS

Our findings suggest that ASA levels do not show a significant association with either the pregnancy rate or the method of conception following vasectomy reversal.

Antisperm Antibody Levels After Vasectomy Reversal Are Not Associated With Pregnancy Rates or Method of Conception

OBJECTIVE

To examine the relationship between antisperm antibody (ASA), pregnancy rates, and method of conception following vasectomy reversal, given that before and after vasectomy reversal, patients wonder if ASAs will prevent them from achieving pregnancy and American Urological Association vasectomy guidelines call for additional research to answer this question.

METHODS

We performed retrospective chart review and phone interview of patients who underwent vasectomy reversal at our institution from 1/1/2000 to 12/31/2018. We excluded patients who underwent vasectomy reversal for pain, or without postoperative semen analysis with ASA. We categorized patients as having low (<50%) or high (≥50%) ASA levels using the first postoperative semen analysis. Our primary outcome was pregnancy rate, including method of conception. Differences in pregnancy rates were tested using Fisher exact test.

RESULTS

Two hundred and four patients were chart reviewed. Median age at time of surgery was 40years and median obstruction interval was 7.3years. Median partner age was 32years. One hundred sixty-four (80%) patients underwent bilateral vasovasostomy. Eighty-five patients (42%) had low (<50%) ASA levels and 119 (58%) had high (≥50%) ASA levels. Sixty-seven patients completed phone interviews. Of 27 men with low ASA levels, 19 (70%) achieved a pregnancy with 16 (59%) spontaneous pregnancy. Of 40 men with high ASA levels, 30 (75%) achieved a pregnancy with 16 (40%) spontaneous pregnancy. The Fisher exact test P-value was .2.

CONCLUSION

ASA levels are not associated with pregnancy rate or method of conception after vasectomy reversal. These findings can improve patient counseling before and after vasectomy reversal.

Characterization of a spontaneously occurring self-reactive antibody against sperm in mice

We previously established a spontaneously occurring monoclonal antibody, namely Ts3, that was reactive to sperm from an aged male mouse. The present study investigated the characteristic properties and reproductive functions of Ts3. Immunofluorescent staining revealed that Ts3 reacted to epididymal sperm, and the corresponding antigen was located in the midpiece and principal piece. Immunohistochemistry revealed positive reactions in the germ cells and Sertoli cells in the testis, the epithelial cells in the epididymis and vas deferens. Through western blotting with two-dimensional electrophoresis, we demonstrated that Ts3 reacted with four spots, which were around Mr ∼25,000-60,000 and pI 5-6. MALDI-TOF/TOF mass spectrometry identified outer dense fiber 2 (ODF2) as a candidate for Ts3. ODF2 is a cytoskeletal structural component located in the midpiece and principal piece of the flagella of mammalian sperm. This was validated with the result of immunofluorescent staining, suggesting that ODF2 was the main target antigen for Ts3. Sperm immobilization test showed that Ts3 possessed sperm immobilizing activity. Furthermore, Ts3 impaired early embryo development but not in vitro fertilization. These results suggest that ODF2 plays an important role in both sperm function and early embryonic development.

The regional distribution of resident immune cells shapes distinct immunological environments along the murine epididymis

The epididymis functions as transition zone for post-testicular sperm maturation and storage and faces contrasting immunological challenges, i.e. tolerance towards spermatozoa vs. reactivity against pathogens. Thus, normal organ function and integrity relies heavily on a tightly controlled immune balance. Previous studies described inflammation-associated tissue damage solely in the distal regions (corpus, cauda), but not in the proximal regions (initial segment, caput). To understand the observed region-specific immunity along the epididymal duct, we have used an acute bacterial epididymitis mouse model and analyzed the disease progression. Whole transcriptome analysis using RNAseq 10 days post infection showed a pro-inflammatory environment within the cauda, while the caput exhibited only minor transcriptional changes. High-dimensional flow cytometry analyses revealed drastic changes in the immune cell composition upon infection with uropathogenic Escherichia coli. A massive influx of neutrophils and monocytes was observed exclusively in distal regions and was associated with bacterial appearance and tissue alterations. In order to clarify the reasons for the region-specific differences in the intensity of immune responses, we investigated the heterogeneity of resident immune cell populations under physiological conditions by scRNASeq analysis of extravascular CD45+ cells. Twelve distinct immune cell subsets were identified, displaying substantial differences in distribution along the epididymis as further assessed by flow cytometry and immunofluorescence staining. Macrophages constituted the majority of resident immune cells and were further separated in distinct subgroups based on their transcriptional profile, tissue location and monocyte-dependence. Crucially, the proximal and distal regions showed striking differences in their immunological landscapes. These findings indicate that resident immune cells are strategically positioned along the epididymal duct, potentially providing different immunological environments required for addressing the contrasting immunological challenges and thus, preserving tissue integrity and organ function.

Bacteriospermia - A formidable player in male subfertility

Bacterial colonization of male reproductive tissues, cells, and fluids, and the subsequent impact of bacteria on the sperm architecture, activity, and fertilizing potential, has recently gained increased attention from the medical and scientific community. Current evidence strongly emphasizes the fact that the presence of bacteria in semen may have dire consequences on the resulting male fertility. Nevertheless, the molecular basis underlying bacteriospermia-associated suboptimal semen quality is sophisticated, multifactorial, and still needs further understanding. Bacterial adhesion and subsequent sperm agglutination and immobilization represent the most direct pathway of sperm-bacterial interactions. Furthermore, the release of bacterial toxins and leukocytic infiltration, associated with a massive outburst of reactive oxygen species, have been repeatedly associated with sperm dysfunction in bacteria-infested semen. This review serves as a summary of the present knowledge on bacteriospermia-associated male subfertility. Furthermore, we strived to outline the currently available methods for assessing bacterial profiles in semen and to outline the most promising strategies for the prevention and/or management of bacteriospermia in practice.

Fertility preservation for patients with melanoma

The advent of immunotherapy and targeted therapy has outstandingly improved the prognosis in subjects with melanoma. Their use is now advocated also in earlier stages as an adjuvant therapy, and some neoadjuvant clinical trials are ongoing. Consequently, survivors free of disease are increasing, as well as those exposed to these new agents. Parenthood in survivors is, therefore, receiving growing interest. Evidence on the effects of immunotherapy and targeted therapy on future fertility is limited, but not entirely reassuring, in particular for immunotherapy. The necessity of delaying pregnancy seeking up to the end of treatments and follow-up (iatrogenic aging) is an additional albeit neglected source of concern, in particular for women in their late 30s. Subjects with melanoma should be informed on the multifaceted issue of future fertility at the time of cancer diagnosis. Available options of fertility preservations, including sperm and oocytes storage, should also be discussed, especially considering that at the age 0-39, melanoma represents the second most frequent neoplasia. In the decision-making process, most attention should be given to sex, age, and exposure to immunotherapy.

Evolution of the World Health Organization semen analysis manual: where are we?

The WHO (World Health Organization) manuals provide state-of-the-art guidance on how a semen analysis should be carried out. The much anticipated sixth edition of the WHO semen analysis manual has been released 10 years after its previous version and includes essential updates, such as new reference standards for semen volume and microscopic sperm characteristics of recent fathers. A well-conducted semen analysis remains an essential foundation of the infertility evaluation process and affects patient referral, diagnosis and treatment. However, a male infertility work-up primarily based on routine semen analysis does not provide men with an optimal fertility pathway; the primary reasons for routine semen analysis inadequacy in this context include its low predictive value for natural and assisted conception success, its inability to detect sperm DNA and epigenetic deficiencies that might negatively affect embryo development, implantation and offspring well-being, and the substantial overlap between semen parameters of fertile and subfertile individuals. Ideally, a full andrological assessment should be carried out by reproductive urologists in all men dealing with couple infertility and should include a detailed history analysis, physical examination, semen analysis, endocrine assessment and other tests as needed. Only through a complete male infertility work-up will relevant underlying medical and infertility conditions be revealed and potentially treated or alleviated. The ultimate goals of a comprehensive andrological assessment are to positively influence overall male health, pregnancy prospects and offspring well-being.

Sperm Physiological Response to Female Serum-Potential New Insights into the Reproductive Incompatibility Diagnostics

Infertility is assumed to arise exclusively from male- and female-dependent pathological factors. However, recent studies have indicated that reproductive failure may also result from the reproductive incompatibility of the partners. Selection against such incompatibilities likely occurs via female-derived reproductive secretions, including follicular fluid (FF), that mediate gamete-level mate choice towards the sperm of specific males. To facilitate potential development of diagnostic tests for human reproductive incompatibility, we examined whether sperm physiological response to female serum indicate male–female compatibility in the presence of FF. We performed a full-factorial experiment, in which the sperm of 10 males were treated with the FF and serum of 6 healthy females. We found that sperm motility and viability in both biofluids were highly similar and that in 70% of the males, sperm serum treatment predicted male–female compatibility. We also identified male human leucocyte antigen (HLA) alleles and female (FF and serum) anti-HLA antibodies and tested whether the number of allele–antibody matches predict sperm physiological response to female fluids. However, no association was found between measured sperm traits and the number of allele–antibody matches. Overall, the present results may open novel possibilities for the future development of reproductive incompatibility tests and may pave the way towards more accurate infertility diagnostics and treatments.

Microenvironment for spermatogenesis and sperm maturation

The male reproductive system consists of testes, a series of ducts connecting the testes to the external urethral orifice, accessory sex glands, and the penis. Spermatogonial stem cells differentiate and mature in testes and epididymides, and spermatozoa are ejaculated with exocrine fluids secreted by accessory sex glands. Many studies have clarified the detailed structure and function of the male reproductive system, and have shown that various biologic controls, including genomics, epigenetics, and the neuroendocrine-immune system regulate proliferation, differentiation, and maturation of germ cells. In other words (1) genetic deletion or abnormalities, (2) aberration of DNA methylation and histone modifications, as well as small RNA dysfunction, and (3) neuroendocrine-immune disorders are involved in functional failure of the male reproductive system. In this article, we review these three factors for germ cell microcircumstance, especially focused on the immunoendocrine environment. In particular, the relation between factors protecting germ cells with strong auto-immunogenicity and opposite factors compromising this protection are discussed. Reductions in sperm count, concentration, and semen quality are serious problems in developed countries, although the causes are complex and remain unclear. The accumulation of basic knowledge regarding the structure, function, and regulation of the male reproductive system under various experimental conditions will be important to resolve these problems.

Pathogenesis of Autoimmune Male Infertility: Juxtacrine, Paracrine, and Endocrine Dysregulation

According to global data, there is a male reproductive potential decrease. Pathogenesis of male infertility is often associated with autoimmunity towards sperm antigens essential for fertilization. Antisperm autoantibodies (ASAs) have immobilizing and cytotoxic properties, impairing spermatogenesis, causing sperm agglutination, altering spermatozoa motility and acrosomal reaction, and thus preventing ovum fertilization. Infertility diagnosis requires a mandatory check for the ASAs. The concept of the blood–testis barrier is currently re-formulated, with an emphasis on informational paracrine and juxtacrine effects, rather than simple anatomical separation. The etiology of male infertility includes both autoimmune and non-autoimmune diseases but equally develops through autoimmune links of pathogenesis. Varicocele commonly leads to infertility due to testicular ischemic damage, venous stasis, local hyperthermia, and hypoandrogenism. However, varicocelectomy can alter the blood–testis barrier, facilitating ASAs production as well. There are contradictory data on the role of ASAs in the pathogenesis of varicocele-related infertility. Infection and inflammation both promote ASAs production due to “danger concept” mechanisms and because of antigen mimicry. Systemic pro-autoimmune influences like hyperprolactinemia, hypoandrogenism, and hypothyroidism also facilitate ASAs production. The diagnostic value of various ASAs has not yet been clearly attributed, and their cut-levels have not been determined in sera nor in ejaculate. The assessment of the autoimmunity role in the pathogenesis of male infertility is ambiguous, so the purpose of this review is to show the effects of ASAs on the pathogenesis of male infertility.