Enrichment of gamma delta T lymphocytes in human semen: relation between gamma delta T cell concentration and antisperm antibody status

Tissue-resident immunity in the female and male reproductive tract

The conception of how the immune system is organized has been significantly challenged over the last years. It became evident that not all lymphocytes are mobile and recirculate through secondary lymphoid organs. Instead, subsets of immune cells continuously reside in tissues until being reactivated, e.g., by a recurring pathogen or other stimuli. Consequently, the concept of tissue-resident immunity has emerged, and substantial evidence is now available to support its pivotal function in maintaining tissue homeostasis, sensing challenges and providing antimicrobial protection. Surprisingly, insights on tissue-resident immunity in the barrier tissues of the female reproductive tract are sparse and only slowly emerging. The need for protection from vaginal and amniotic infections, the uniqueness of periodic tissue shedding and renewal of the endometrial barrier tissue, and the demand for a tailored decidual immune adaptation during pregnancy highlight that tissue-resident immunity may play a crucial role in distinct compartments of the female reproductive tract. This review accentuates the characteristics of tissue-resident immune cells in the vagina, endometrium, and the decidua during pregnancy and discusses their functional role in modulating the risk for infertility, pregnancy complications, infections, or cancer. We here also review data published to date on tissue-resident immunity in the male reproductive organs, which is still a largely uncharted territory.

Microbiota-dependent expansion of testicular IL-17-producing Vγ6+ γδ T cells upon puberty promotes local tissue immune surveillance

γδT cells represent the majority of lymphocytes in several mucosal tissues where they contribute to tissue homoeostasis, microbial defence and wound repair. Here we characterise a population of interleukin (IL) 17-producing γδ (γδ17) T cells that seed the testis of naive C57BL/6 mice, expand at puberty and persist throughout adulthood. We show that this population is foetal-derived and displays a T-cell receptor (TCR) repertoire highly biased towards Vγ6-containing rearrangements. These γδ17 cells were the major source of IL-17 in the testis, whereas αβ T cells mostly provided interferon (IFN)-γ in situ. Importantly, testicular γδ17 cell homoeostasis was strongly dependent on the microbiota and Toll-like receptor (TLR4)/IL-1α/IL-23 signalling. We further found that γδ17 cells contributed to tissue surveillance in a model of experimental orchitis induced by intra-testicular inoculation of Listeria monocytogenes, as Tcrδ-/- and Il17-/- infected mice displayed higher bacterial loads than wild-type (WT) controls and died 3 days after infection. Altogether, this study identified a previously unappreciated foetal-derived γδ17 cell subset that infiltrates the testis at steady state, expands upon puberty and plays a crucial role in local tissue immune surveillance.

T Lymphocytes and Testicular Immunity: A New Insight into Immune Regulation in Testes

The immune privilege of the testes is necessary to prevent immune attacks to gamete-specific antigens and paternal major histocompatibility complex (MHC) antigens, allowing for normal spermatogenesis. However, infection and inflammation of the male genital tract can break the immune tolerance and represent a significant cause of male infertility. Different T cell subsets have been identified in mammalian testes, which may be involved in the maintenance of immune tolerance and pathogenic immune responses in testicular infection and inflammation. We reviewed the evidence in the published literature on different T subtypes (regulatory T cells, helper T cells, cytotoxic T cells, γδ T cells, and natural killer T cells) in human and animal testes that support their regulatory roles in infertility and the orchitis pathology. While many in vitro studies have indicated the regulation potential of functional T cell subsets and their possible interaction with Sertoli cells, Leydig cells, and spermatogenesis, both under physiological and pathological processes, there have been no in situ studies to date. Nevertheless, the normal distribution and function of T cell subsets are essential for the immune privilege of the testes and intact spermatogenesis, and T cell-mediated immune response drives testicular inflammation. The distinct function of different T cell subsets in testicular homeostasis and the orchitis pathology suggests a considerable potential of targeting specific T cell subsets for therapies targeting chronic orchitis and immune infertility.

γδ T cells in tissue physiology and surveillance

γδ T cells are a unique T cell subpopulation that are rare in secondary lymphoid organs but enriched in many peripheral tissues, such as the skin, intestines and lungs. By rapidly producing large amounts of cytokines, γδ T cells make key contributions to immune responses in these tissues. In addition to their immune surveillance activities, recent reports have unravelled exciting new roles for γδ T cells in steady-state tissue physiology, with functions ranging from the regulation of thermogenesis in adipose tissue to the control of neuronal synaptic plasticity in the central nervous system. Here, we review the roles of γδ T cells in tissue homeostasis and in surveillance of infection, aiming to illustrate their major impact on tissue integrity, tissue repair and immune protection.

Association between a PD-1 gene polymorphism and antisperm antibody-related infertility in Iranian men

OBJECTIVE

Programmed cell death-1 (PD-1, Pdcd1), an immunoreceptor belonging to the CD28/CTLA-4 family negatively regulates antigen receptor signalling by recruiting protein tyrosine phosphatase, SHP-2 upon interacting with either of two ligands, PD-L1 or PD-L2. This study investigates PD-1 gene polymorphism in patients with antisperm antibody-related infertility

METHODS

Genotyping was performed by polymerase chain reaction and restriction enzyme digestion (PCR-RFLP), this polymorphism was genotyped in 145 Iranian subjects (61 patients with antisperm antibody-related infertility and 84 healthy controls).

RESULTS

Patients frequencies of the G/A genotype in comparison with healthy controls (38.2 % vs. 32.7 %, OR =1.21, P = 0.35) were not significantly different. However, G/G and A/A genotype frequencies between patients and healthy controls were significantly different (P = 0.042, P = 0.00001, respectively). Also, allele frequencies of this polymorphism were significantly different (P = 0.0012) in patients compared to healthy controls.

CONCLUSION

According to these results, there is a correlation between PD-1 gene polymorphism and susceptibility to antisperm antibody-related infertility in our study group.

Immune regulation in the male genital tract

Spermatozoa are not produced until puberty, long after the establishment of tolerance to self-antigens. Therefore, sperm-specific antigens are immunogenic in men. Most men, however, do not produce antibodies to their own gametes. Development of mechanisms to prevent or limit autoimmune responses to spermatozoa were essential for preservation of reproductive capacity. Tight junctions between adjacent Sertoli cells, as part of the blood-testis barrier, prevent sperm-immune cell contact. In some portions of the genital tract this barrier is thin or incomplete. Immune mechanisms have evolved to actively suppress the autoimmune response to spermatozoa within the genital tract. Unlike in the circulation where CD(4+) helper T lymphocytes predominate, CD(8+) suppressor/cytotoxic T lymphocytes are the most prominant T cells in the epididymis and vas deferens. In addition, spermatozoa suppress pro-inflammatory lymphocyte immune responses, possibly by inducing production of anti-inflammatory cytokines. Antisperm antibody production is induced in the male genital tract when a local infection or disruption in the genital tract physical barrier leads to an influx of CD(4+) T cells. In response to induction of a productive immune response, two additional mechanisms downregulate humoral immunity within the genital tract. T lymphocytes possessing the gammasigma form of the antigen receptor (gammasigma T cells) are concentrated in the male genital tract and in semen. These cells become activated and proliferate in men with evidence of sperm autoimmunity. Activated gammasigma T cells inhibit production of antibodies by activated B lymphocytes, thereby limiting antisperm antibody production. Heat shock proteins (hsps) are also present in semen in association with infection and antisperm antibody formation. Hsp gene transcription leads to inhibition of transcription of the genes coding for pro-inflammatory cytokines and, conversely, to activation of gammasigma T cells. Activated gammasigma T cells also promote hsp synthesis. The mechanisms to inhibit immunity to sperm may hinder effective immune elimination of microoganisms in the male genital tract.

Chlamydia trachomatis infection is related to poor semen quality in young prostatitis patients

BACKGROUND

The impact of chronic prostatitis resulting from Chlamydia trachomatis infection on male fertility is controversial.

OBJECTIVE

To investigate the correlation between C. trachomatis infection and semen quality in young male patients affected by chronic prostatitis resulting from C. trachomatis infection and to evaluate the correlation between anti-C. trachomatis immunoglobulin (Ig) A against heat shock protein 60 (HSP60), heat shock protein 70 (HSP70), and semen parameters.

DESIGN, SETTING, AND PARTICIPANTS

All patients with clinical and instrumental diagnosis of chronic prostatitis underwent microbiological cultures for common bacteria, DNA extraction, mucosal and serum antibody evaluation for C. trachomatis, and semen parameter analysis. Western blot analysis of mucosal anti-C. trachomatis IgA was performed.

INTERVENTIONS

Subjects were split into two groups: Group A consisted of patients with chronic prostatitis resulting from common bacteria (uropathogens), and group B consisted of patients with chronic prostatitis resulting from C. trachomatis infection.

MEASUREMENTS

The relationship between C. trachomatis infection and semen parameters as well as the correlation among IgA levels, IgA characterisation, and semen analysis were determined.

RESULTS AND LIMITATIONS

We enrolled 1161 patients (mean age: 36.5 yr). Of these, 707 patients were placed in group A, and 454 were placed in group B. Significant statistical differences were reported between groups in terms of sperm concentration (p<0.001), percentage of motile sperm (p<0.001), and normal morphologic forms (p<0.001). Strong correlations between mucosal anti-C. trachomatis IgA and sperm concentration (p<0.001) and normal morphologic forms (p<0.001) were reported. Correlations among positivity to HSP60, HSP70, and sperm concentration (p<0.003) and normal morphologic forms (p<0.001) were also reported.

CONCLUSIONS

This study demonstrated the role of chronic prostatitis resulting from C. trachomatis in male fertility decrease, highlighting probable immunomediated damage to germinal cells because of C. trachomatis infections.

Is benign prostatic hyperplasia (BPH) an immune inflammatory disease?

OBJECTIVES

Chronic inflammation has been documented for years in benign prostatic hyperplasia (BPH), but only now has it become evident as a major factor in disease progression. This review highlights the immunologic key features of chronic inflammation in BPH and the present interpretation of these changes in the development and progression of BPH.

RESULTS

Almost all BPH specimens show inflammatory infiltrates at histologic examination, but correlation to bacterial or other foreign antigens has not been established. Recognition of prostate secretion products by autoreactive T cells and animal models on experimental prostatitis demonstrate an autoimmune component to chronic inflammation. The infiltrate consists predominantly of chronically activated CD4(+) T lymphocytes, which are permanently recruited to prostate tissue via elevated expression of interleukin 15 (IL-15) and interferon gamma (IFN-gamma), proinflammatory cytokines produced by smooth muscle and T cells, respectively. With the appearance of infiltrates, T cell-derived cytokine production of IFN-gamma, IL-2, and transforming growth factor beta increases, the former two ultimately reaching 10-fold and the latter 2-fold higher levels in fully developed BPH than in normal prostates. As "mature" BPH nodules develop, IL-4 and IL-13 expression increases >2-fold, corresponding to a T-helper (Th)0/Th2 cytokine pattern. Dysregulation of the immune response in BPH may occur via elevated expression of proinflammatory IL-17, which stimulates a multifold production of IL-6 and IL-8, key executors of stromal growth in BPH.

CONCLUSIONS

These data strongly suggest that BPH is an immune inflammatory disease. Unravelling the specific nature of immune dysregulation may help design novel drugs with these specific targets in mind.

Antichlamydial and Antisperm Antibodies in Patients with Chlamydial Infections

PROBLEM

Establishing the correlation between antichlamydial antibodies (AchAbs) and antisperm antibodies (ASA) in patients with chlamydial infections.

METHOD OF STUDY

ASA were studied in sera from patients (142 with genital, 57 with ocular chlamydial infections) and control group (n = 100) by gelatin and tray agglutination test (TAT), sperm immobilization test (SIT) and ELISA. AchAbs were revealed by ELISA.

RESULTS

A significantly higher (P < 0.05) ASA incidence was noted in patients with genital infections as compared with controls and patients with ophthalmologic infection (P < 0.0001), but not between patients with ophthalmologic infection and controls (P > 0.05). A significant correlation was established between AchAbs and ASA for TAT (r = 0.8214, P = 0.0341), SIT (r = 0.797, P = 0.032) and ELISA (r = 0.8519, P = 0.0313) in patients with genital infections only.

CONCLUSIONS

The genital Chlamydia infection may play a role in the induction of ASA. This is probably a result of the inflammatory process, but not of cross-reactivity between sperm and Chlamydia trachomatis antigens.

Isolation and characterisation of T lymphocytes from the urethra of patients with acute urethritis

OBJECTIVES

To investigate local cellular immune responses in patients with acute urethritis.

METHODS

We have established T cell lines from the urethral exudate and examined their phenotype by flow cytometry. As controls, T cell lines were cultured from first pass urine specimens of asymptomatic healthy individuals.

RESULTS

Using interleukin 2 (IL-2) alone a T cell line was obtained on only one occasion. Following culture with IL-2, and subsequent expansion by a single stimulation with irradiated allogenic peripheral blood mononuclear cells (PBMC), phytohaemagglutinin (PHA), and IL-2, it was possible to establish T cell lines from 6/6 acute urethritis patients. T cell lines were also obtained from 4/12 controls subjects, but required repetitive rounds of stimulation with mitogen and allogeneic PBMC to produce sufficient cell numbers for analysis. Three of the patient T cell lines were dominated by T cells expressing the gamma delta receptor.

CONCLUSION

The gamma delta T cell subset has been associated with immune responses at mucosal surfaces and has the ability to recognise certain bacterial antigens. The gamma delta T cell response may represent an important aspect of the immune response to organisms associated with acute urethritis.

Nonsperm cells in human semen: with special reference to seminal leukocytes and their possible influence on fertility

Nonspermatozoal cells (NSC) in semen, including immature germ cells, leukocytes (WBC) and epithelial cells, are normally found in a concentration less than 15% of the sperm concentration. Cytological staining methods and immunoenzymatic assays for characterization of seminal WBC and methods for detection of various enzymes from WBC are evaluated. Criteria for abnormally high levels of WBC in semen, caused by exogenic factors (e.g., infection) and possibly by endogenic factors (e.g., abnormal sperm), are discussed. Leukocytospermia is associated with reduced in vitro fertilization rate, and experimentally-measured sperm functions (e.g., motility) are inhibited by high concentrations of certain WBC products (e.g., reactive oxygen species and interferon-gamma). At the present stage, the following procedures could be used to evaluate WBC in ejaculates from infertile patients: (1) count the number of NSC using a hemocytometer. (2) Determine the number of WBC in percentage of NSC in smears using the Papanicolaou staining technique, or an immuno-enzymatic assay using monoclonal antibodies to the different kinds of WBC. (3) If, abnormally high levels of WBC (according to the WHO criteria or based on a percentile determined from examination of normal, fertile men) is detected, a second ejaculate should be examined 3 months later. (4) Persistent leukocytospermia should indicate physical and microbiological examinations, after which antibiotic treatment may be indicated.

Gamma delta T-cell subset distribution in human semen from fertile donors

PROBLEM

Gamma delta T-cell subset distribution has not been fully investigated in normal human semen.

METHODS

We therefore carried out experiments by using a direct immunofluorescence staining technique followed by two-color cytofluorimetric analysis on mononuclear cell (MC) suspensions from ejaculates of ten healthy, fertile volunteers. Autologous peripheral blood MC were simultaneously analyzed and the results used for statistical comparison.

RESULTS

The proportion of normal human semen lymphocytes bearing the gamma delta T-cell receptor for antigen was greatly increased compared with autologous circulating counterparts. Interestingly, the rise was mainly due to an overexpansion of cells expressing V delta 1 gene-encoded determinants on their surface. This contrasts with the normal blood picture, where most gamma delta T cells express V delta 2 conformational epitopes.

CONCLUSIONS

The numerical and phenotypical differences in semen gamma delta T lymphocytes provide further evidence of a defined migrating lymphocyte subset balance in anatomically and physiologically distinct areas of the body. Their functional role, in terms of both helper and suppressor-cytotoxic activities in the nonsterile proximal portions of the male genital tract, now needs to be explored in detail.

The biologic significance of white blood cells in semen

OBJECTIVE

To analyze the data available on the biologic significance of white blood cells (WBC) in semen of infertility patients.

DATA RESOURCES

The relevant literature was reviewed.

RESULTS

It is not possible to identify reliably WBC by conventional sperm staining techniques. The peroxidase method is sufficient for quantification of granulocytes, but immunocytology is the gold standard for the detection of all WBC populations in semen. Granulocytes are the most prevalent WBC type in semen (50% to 60%), followed by macrophages (20% to 30%) and T-lymphocytes (2% to 5%). The prevalence of leukocytospermia (> 10(6) WBC/mL semen) among male infertility patients is approximately 10% to 20%. There is controversy on the significance of WBC in semen. Whereas some authors did not observe sperm damage in the presence of leukocytospermia, others have found evidence that WBC are significant cofactors of male infertility: [1] seminal WBC numbers were higher in infertility patients than among fertile men; [2] leukocytospermia was associated with decreased sperm numbers and impaired sperm motility; [3] WBC damaged sperm function and hamster ovum penetration in vitro and were important prognostic factors for IVF-ET failure. Because of absence of clinical symptoms, the origin of WBC is difficult to determine. Normally, most WBC appear to originate from the epididymis because vasectomized men show very few WBC in semen. On the other hand, leukocytospermic samples show low citric acid levels, pointing to asymptomatic prostatitis as a source of WBC in semen. Surprisingly, approximately 80% of leukocytospermic samples are microbiologically negative. In some cases Chlamydia trachomatis might have triggered a persistent inflammatory reaction leading to leukocytospermia. Sperm damage by WBC can be mediated by reactive oxygen species, proteases and cytokines. Furthermore, genital tract inflammation facilitates the formation of sperm antibodies. As seminal plasma has strong anti-inflammatory properties and because there is only short contact between sperm and WBC in prostatitis and seminal vesiculitis, inflammations of the epididymis and testis are likely to have the largest impact on sperm.

CONCLUSIONS

There is ample evidence that WBC can affect sperm function. Further studies are needed to define cofactors that increase or decrease the risk of sperm damage by WBC.

Activation of circulating gamma delta T-lymphocytes by autologous sperm from men sensitized to sperm

The in vitro proliferative responses to sperm of T-lymphocytes bearing the alpha beta or gamma delta form of the antigen receptor were investigated. Peripheral blood mononuclear cells from five men without antisperm antibodies and eight men with antisperm antibodies both on sperm and in serum were incubated for 72 h in the presence of an equal concentration of autologous live sperm, freeze-thawed sperm and heat-killed sperm. Prior to incubation and after 72 h, aliquots were applied to Teflon coated microscope slides, which were subsequently incubated with monoclonal antibodies to the beta chain and delta chain of the human T-cell receptor. Urethral samples were cultured for bacteria and tested for Chlamydia trachomatis by direct staining and by ELISA. The four men with chlamydial infections had the highest concentrations of circulating gamma delta T-cells (P = 0.0008). The concentration of gamma delta T-cells from men with antisperm antibodies increased 245% over the buffer control in response to live sperm (P < 0.0001). Proliferation of gamma delta T-cells was also seen to a lesser extent in response to freeze-thawed (P = 0.002) and heat killed (P = 0.03) sperm. In contrast, gamma delta T-cells from men without antisperm antibodies proliferated only marginally (36%) in response to live sperm (P = 0.05) and were unresponsive to non-viable sperm. Only from men sensitized to sperm were alpha beta T-cells responsive, to a small extent, to live sperm (P = 0.04). Thus, in men with antisperm antibodies, peripheral gamma delta and alpha beta T-cells appeared to be sensitized to antigens on the surface of viable sperm. The immune response of gamma delta T-cells to sperm may be a useful in vitro system to examine the mechanism of gamma delta T-cell activation.