Immunoglobulin (Ig) G, IgA, and IgA subclass antibodies against fertilization antigen-1 in cervical secretions and sera of women of infertile couples

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.

Role of cathepsin E in decidual macrophage of patients with recurrent miscarriage

In a previous study, we reported that the cathepsin-cystatin system caused endometrial dysfunction in early pregnancy. Here, we investigated the existence and contribution of cathepsin E in early pregnancy in patients with recurrent miscarriage (RM). The effect of cathepsin deficiency on fertility and female reproductive organs were also analyzed in CatE(-/-) mice. Human studies were conducted in a hospital setting, with informed consent. Cervical mucus was collected from RM patients in early pregnancy (4-6 gestational weeks, n = 21), and the pregnancy outcome was compared prospectively. The cathepsin E expression in decidua of RM patients (n = 49) and normal pregnant women undergoing elective surgical abortion (n = 24) was measured using SDS-PAGE, and western blot analysis. Decidual macrophages were isolated from RM patients (n = 6) and stimulated by lipopolysaccharide (LPS) and interferon gamma (IFN-γ). Results from the mouse model showed that CatE(-/-) mice were fertile, but the litter number was significantly smaller. The uterus of CatE(-/-) mice showed granulation tissue. In human samples, protease activity of cathepsin E measured with Fluorescence-Quenching Substrate (KYS-1) in cervical mucus of patients who developed miscarriage was markedly decreased compared with patients without RM. The expression of cathepsin E in decidua, semi-quantified by SDS-PAGE, western blot analysis was significantly lower in RM patients compared with patients without RM. By double staining immunofluorescence, the staining of cathepsin E was observed in CD14 or CD68 positive cells in all deciduas. Upon stimulation with LPS and IFN-γ, the expression of cathepsin E in cell lysate of decidual macrophages was markedly reduced in RM patients compared with controls. The results suggested that decreased activity of cathepsin E produced by decidual macrophages might be responsible for the induction of miscarriages in some RM patients.

Determinants and correlation of systemic and cervical concentrations of total IgA and IgG

We compared systemic and cervical total IgA and IgG during the menstrual cycle among 154 women who attended clinic visits at follicular/early, periovulatory/mid, and luteal/late phases of menstrual cycle. Paired serum and cervical secretions were tested at each visit for total IgA and IgG using ELISA. Geometric mean titers for systemic IgA and IgG were 1.92 and 8.25 mg/mL, respectively. There were no differences in titers by menstrual cycle phase, neither were they correlated to cervical titers (rho = 0.17 and 0.16, respectively). The lack of correlation between systemic and cervical total IgA and IgG suggests that systemic concentrations are not reflective of cervical levels.

Modalities for treatment of antisperm antibody mediated infertility: novel perspectives

Immunoinfertility because of antisperm antibodies (ASA) is an important cause of infertility in humans. The incidence of ASA in infertile couples is 9-36% depending on the reporting center. Early claims regarding the incidence and involvement of ASA in involuntary infertility were probably overemphasized, which has resulted in subsequent confusion, doubt, and underestimation of their clinical significance. No immunoglobulin that binds to sperm should be called an antisperm antibody in a strict sense unless it is directed against a sperm antigen that plays a role in fertilization and fertility. ASA directed against the fertilization-related antigens are more relevant to infertility than the immunoglobulins that bind to sperm associated antigens. Several methods have been reported for treatment of immunoinfertility. These include: immunosuppressive therapies using corticosteroids or cyclosporine; assisted reproductive technologies such as intrauterine insemination, gamete intrafallopian transfer, in vitro fertilization, and intracytoplasmic sperm injection; laboratory techniques such as sperm washing, immunomagnetic sperm separation, proteolytic enzyme treatment, and use of immunobeads. Most of the available techniques have side effects, are invasive and expensive, have low efficacy, or provide conflicting results. Recent findings using defined sperm antigens that have a role in fertilization/fertility have provided animal models and innovative novel perspectives for studying the mechanism of immunoinfertility and possible modalities for treatment. The better understanding of local immunity and latest advances in hybridoma and recombinant technologies, proteomics and genomics leading to characterization of sperm antigens relevant to fertility will help to clarify the controversy and to establish the significance of ASA in infertility.

Characterization of spermatozoa surface antigens by antisperm antibodies and its influence on acrosomal exocytosis

PROBLEM

Antisperm antibodies (ASA) are the main cause of immunological infertility, they impair sperm functions by binding to the sperm membrane. The aim of this study was to characterize highly enriched sperm membrane proteins by 2-D-electrophoresis and to identify membrane antigens binding ASA and to evaluate the influence of ASA on the acrosome reaction (AR).

METHOD OF STUDY

Sperm membrane proteins were separated by 2-D-electrophoresis and antigens were identified by immunoblotting with ASA from seminal plasma samples of infertile men. The influence of ASA on the AR were observed and determined by means of flowcytometry.

RESULTS

A total of 18 antigens were identified by using ASA from seminal plasma. Six of the recognized proteins were analyzed by means of mass spectrometry and peptide matching: HSP70 and HSP70-2, disulfide-isomerase-ER60, caspase-3 and two subunits of the proteasome (component-C2 and zeta-chain). ASA from seminal plasma are able to enhance the AR in donor-spermatozoa.

CONCLUSION

The biochemical identification of these proteins will be helpful to understand the mechanism by which ASA impair sperm function and the fertilization process. Spermatozoa, in which the AR was prematurely induced by ASA, will not be able to fertilize anymore.

Molecular and immunological characteristics of sperm antigens involved in egg binding

Development of a vaccine(s) based on sperm antigens represents a promising approach to contraception. The utility of an antigen in immunocontraception is contingent upon sperm/testis-specificity and its involvement in the fertilization process. Since, the sperm-zona pellucida (ZP) recognition and binding constitutes the most important event in the fertilization process, molecules involved at this site are attractive candidates for immunocontraception. Using hybridoma technology, subtractive hybridization, and differential display technology, our laboratory has delineated several sperm antigens. These antigens have testis-specific expression and have a role in the fertilization process. The cDNAs encoding for the antigens have been cloned and sequenced. Among these, the fertilization antigen (FA-1) is particularly interesting, because it is involved in immuno-infertility in humans. Using the phage peptide display technique, a novel dodecamer sequence of a approximately 72+/-5 kD antigen, designated as YLP(12), that is testis-specific and involved in human sperm-ZP recognition/binding, was identified. A synthetic 12-mer peptide was generated based on this sequence. In the hemizona assay, YLP(12) peptide and its monovalent Fab' antibodies specifically and significantly inhibited human sperm-ZP binding. Furthermore, the presence of specific antibodies reactive with YLP(12) peptide, were identified in the serum and seminal plasma of immuno-infertile men. Thus, FA-1 and YLP(12) are promising target antigens for the development of contraceptive vaccines as well as for specific diagnosis and treatment of male infertility.

Vaccine for contraception targeting sperm

Development of a vaccine(s) based on sperm antigens represents a promising approach to contraception. The utility of a sperm antigen in immunocontraception is contingent upon its tissue specificity, involvement in fertility and on raising high antibody titer, especially locally in the genital tract, that is capable of inducing reversible infertility. Several sperm antigens, such as lactate dehydrogenase C4, PH-20, sperm protein (SP)-10, fertilization antigen (FA)-1, FA-2, cleavage signal (CS)-1, NZ-1, and NZ-2 have been proposed as potential candidates for the vaccine development. Spermzona pellucida (ZP) binding is a pivotal tissue- and mostly species-specific event in the fertilization process, and the molecules involved in this site constitute the most exciting candidates for immuno-contraception. FA-1 is a sperm-specific glycoprotein having receptor activity for ZP recognition and binding. Complementary DNA encoding for FA-1 antigen has been cloned and sequenced. Active immunization of animals with recombinant FA-1 antigen causes a long-lasting reversible inhibition in fertility by raising a sperm-specific immune response. This antigen is also involved in human immunoinfertility. The exciting findings from the recent trial in immunoinfertile couples indicate that the FA-1 antigen may have clinical application in the treatment of male infertility. A vaccine having most appropriate tissue-specific and effective recombinant and/or synthetic epitopes of various sperm antigens, such as the FA-1 antigen, in a single formulation may provide a highly immunogenic and efficacious antisperm vaccine for contraception. The advances made during the last 5 years suggest that it may be a realistic proposition.

Interleukins-6 and -8 levels in sera and cervical mucus of fertile, idiopathic infertile, and immunoinfertile women: implication in infertility

PROBLEM

The purpose of this study was to investigate the levels of interleukin-6 and -8 (IL-6 and IL-8) in sera and cervical mucus of infertile (idiopathic and immunoinfertile) women and to compare the levels with those in age-matched normally cycling fertile women.

METHODS

Levels of IL-6 and IL-8 were measured in the sera and cervical mucus of fertile and infertile women by the enzyme-linked immunosorbent assay (ELISA). A non-parametric Mann-Whitney test was used to evaluate significance between the means. Linear regression analysis of IL-6 and IL-8 concentrations in serum versus cervical mucus and with antisperm antibody titers was performed by condition as well as all groups together. P < 0.05 was considered significant.

RESULTS

Both IL-6 and IL-8 were detected in sera and cervical mucus of fertile as well as infertile groups. Although serum levels of IL-6 and IL-8 were significantly different between fertile and infertile groups, the differences were more pronounced in the cervical mucus samples. Cervical mucus of idiopathic and immunoinfertile women demonstrated significantly (P = 0.002 to < 0.0001) greater concentrations of IL-6 and IL-8 compared to fertile controls. In general, there was no significant correlation between the serum and cervical mucus IL-6 and IL-8 levels, whether analyzed by condition or all groups together.

CONCLUSIONS

Elevated levels of IL-6 and IL-8 in cervical mucus of infertile groups may play a role in etiology of idiopathic and immunologic infertility. These findings suggest that the measurements of cytokines (especially IL-6 and IL-8) in cervical mucus may provide a tool for specific diagnosis and possibly treatment of infertility, especially idiopathic infertility.

Infertility due to antisperm antibodies

Immunoinfertility is an important problem, involving a significant number of infertile couples. Although the presence of antibodies on sperm has better prognostic value than those in serum or seminal plasma, it may not be the sole authentic evidence of immunoinfertility. Infertility from antisperm antibodies is likely only when they bind to a relevant sperm antigen involved in a specific fertility function. The variance in functional deficits seen in immunologic infertility is most likely related to antibodies directed at different sperm antigens or different class, subclass, or isotypes. Antibodies to FA-1 seem to be of significant importance in human immunoinfertility. In approaching couples with infertility, a high index of suspicion for antibodies is necessary to avoid misdiagnosis. In the optimal situation, all semen analyses should be screened for sperm-bound antibodies, but if this is impractical, testing should be performed on high-risk individuals (Table I). In couples in which the man has sperm-bound antibodies, and in whom there is no identifiable female factor, treatment should be instituted. Most treatments for immunoinfertility have been disappointing because of poor results, adverse effects, or high cost. Corticosteroid therapy has shown some promise in published reports (mostly poorly designed studies), but increase in pregnancy rate is modest and adverse effects may be significant. In our opinion, informed consent should be documented prior to institution of corticosteroid therapy, and subjects should be closely monitored. Advanced reproductive technologies offer a higher safety profile, and, with increasing technology, higher pregnancy rates. We recommend progressing from "low-tech" procedures, such as IUI and reserving the higher level procedures, such as IVF and ICSI, for those couples in whom pregnancy does not occur. The highest level reproductive technologies give the best current prospects for pregnancy in patients with this difficult problem but also are invasive and costly. It is hoped that further work in the laboratory will give rise to newer, safer, and less expensive effective treatments in the very near future.

Detection of immunoglobulin A anticardiolipin antibodies in cervical mucus from in vitro fertilization patients and fertile women

OBJECTIVE

To identify and quantify antiphospholipid autoantibodies of the immunoglobulin (Ig) A isotype in cervical mucus obtained from IVF patients and fertile controls.

DESIGN

The study was performed prospectively. Blood and cervical mucus samples were obtained from patients undergoing IVF treatment (n = 27) at the time of expected E2 peak, before administering hCG. Control samples were taken from fertile women (n = 16) around the time of ovulation during a spontaneous nonstimulated menstrual cycle. Anticardiolipin activity was tested using ELISA.

SETTING

Infertility and IVF unit of an academic tertiary referral medical center and university-based basic research laboratory.

RESULTS

Forty-eight percent (13/27) of the IVF patients and 43.8% (7/16) of the fertile controls exhibited anticardiolipin IgA activity in aspirated cervical mucus. The mean activity measured for the positive cases was similar in both groups. This activity was higher than that measured in peripheral blood of the women studied. No difference was noted between infertile patients undergoing IVF treatment and fertile women in this respect.

CONCLUSIONS

In this preliminary work, we demonstrated for the first time anticardiolipin IgA activity in human cervical mucus. These observations have to be substantiated by larger scaled studies to assess their possible clinical significance.

Levels of interferon-gamma and tumor necrosis factor-alpha in sera and cervical mucus of fertile and infertile women: implication in infertility

Concentrations of two immune cytokines, namely interferon-gamma (INF-gamma) and tumor necrosis factor-alpha (TNF-alpha), were determined in the sera and cervical mucus samples of fertile (n = 16), idiopathic infertile (n = 44), and immunoinfertile women (n = 45) to investigate their role, if any, in female infertility. Sera of idiopathic infertile women demonstrated significantly (P < 0.0001) higher levels of INF-gamma compared to those in fertile controls, whether expressed as pg/ml or pg/mg serum protein. Similarly, sera of immunoinfertile women demonstrated significantly (P = 0.0008) higher levels of INF-gamma compared to fertile controls and idiopathic infertile women. Cervical mucus of idiopathic infertile women also demonstrated significantly (P < 0.0001) higher concentrations of INF-gamma compared to those in fertile controls. Cervical mucus of immunoinfertile women demonstrated significantly (P < 0.0001) higher concentrations of INF-gamma compared to those in fertile controls and idiopathic infertile women. INF-gamma levels in serum did not significantly (P > 0.05) correlate (r = 0.12-0.43) with the concentrations in cervical mucus, when all the three groups were compared together. However, when the serum levels were compared with the cervical mucus concentrations by condition, only the idiopathic infertile group showed a significant (P = 0.005) correlation (r = 0.70). Serum levels of TNF-alpha did not differ significantly (P > 0.05) among three groups of women. Cervical mucus concentrations of TNF-alpha, however, varied among groups with levels being significantly (P = 0.04) higher-in idiopathic infertile women compared with fertile controls and in immunoinfertile women significantly (P = 0.0007) higher than in fertile controls as well as idiopathic infertile women. TNF-alpha levels in serum correlated (r = 0.65) significantly (P < 0.001) with the concentrations in cervical mucus when all the three groups were compared together or individually by infertility condition. These findings suggest the involvement of cytokines in infertility, and thus may have potential applications in diagnosis and treatment of female infertility.

Antisperm antibodies: origin, regulation, and sperm reactivity in human infertility

OBJECTIVE

To follow-up and expand discussion on the action mechanisms of antisperm antibodies in human infertility, the etiology and control of antisperm antibody induction, sperm antigens involved in immunoinfertility, and strategies for therapy.

DESIGN

A review of the recent literature with an emphasis on female immunoinfertility.

RESULTS

The role of antisperm antibodies in clinical infertility continues to be defined. Through assisted reproductive technologies, antisperm antibodies were shown to exert detrimental effects on different prefertilization and possibly postfertilization events. The female reproductive tract is part of the common mucosal immune system and is able to mount effective immune responses against infectious agents, foreign antigens, and, occasionally, sperm cells. Sperm membranes and constituents contain numerous antigenic components foreign to the human body, and yet antisperm antibodies become problematic in few women exposed to semen. Semen and sperm cells contain immunosuppressive factors capable of inhibiting different immune cells. Fertile women apparently produce antisperm antibodies but also possess neutralizing serum anti-idiotypic antibodies that are lacking in virgin and immunoinfertile women.

CONCLUSIONS

Antisperm antibodies can affect adversely human fertility but normally may be controlled by anti-idiotypic antibodies, which along with immunosuppressor factors in semen prevent their induction to a significant degree. This balance between detrimental and "beneficial" immune response to sperm may be shifted toward an antisperm antibody response by stimulatory factors such as infection. Therapies may be devised to stimulate the anti-idiotypic antibody system, to induce immune tolerance to sperm antigens, and to use antigens to adsorb antisperm antibodies from spermatozoa.