2. Male autoimmune infertility: anti-sperm antibodies (ASA)

Sperm are specialized haploid cells with autoantigenic and isoantigenic potential. Thus, ASA can be present in blood, semen, follicular fluid and cervicovaginal secretions affecting sperm movement, capacitation, fertilization and embryo implantation [13, 14]. ASA are far more frequent than oocyte antibodies.

In testis, the Sertoli cells through tight junctions form the impervious blood-testis barrier of two compartments: basal and adluminal. Basal compartment, which houses spermatogonia and young spermatocytes, is connected to vasculature through phagocytic Sertoli cells, which in turn act as antigen presenting cells to induce tolerance. The adluminal surface housing sperm undergoing meiosis and spermiogenesis is segregated from vasculature. Thus leakage of autoantigens from basal compartment can potentially generate ASAs. However, the exact mechanism of ASA generation is still unclear [13]. In some cases, Human Leucocyte Antigen system is associated with ASA and AI [15]. In 0.9–4% of normal fertile adult males as well as pre-pubertal boys, ASA are found in blood serum, seminal plasma, or directly attached to sperm surface indicating these to be NAbs generating confusion on their role in human infertility [16, 17].

Very few ASA are sperm specific [18] and never directed to multiple organs (except in animals). These can appear more frequently due to testicular failures: cryptorchidism, undescended testes, mobile testes and orchitis (especially due to infectious diseases such as mumps). Additionally, varicocele increases the risk of ASA production by two-fold [19]. The reduced testosterone levels due to altered Leydig cell function in undescended testes could theoretically result in reduced T regulatory cells and compromised central tolerance, however, exact mechanism is unclear. Elevated ASA could lead to low sperm count or low progressive motility. Hence, surgery at an early age, followed by steroid therapy to suppress immune reaction is recommended to prevent future infertility in cases with testicular failure.

autoimmune failure could result from an activated immune system or by anti-ovarian antibodies (AOA) alone as described in endometriosis patients [6]. Other reproductive disorders such as POI, polycystic ovary syndrome (PCOS), unexplained infertility, and repeatedly unsuccessful IVF attempts may be responsible for the pathophysiology of preeclampsia or spontaneous

Immune dysregulation is the cause of unexplained or idiopathic infertility in 20–30% of infertile couples [12]. AI is diagnosed when spontaneously synthesized antibodies bind or react with sperm/oocyte to prevent any one or several events: fertilization, acrosome reaction, capacitation or embryo implantation. Despite much research into organ specific biomarkers, no specific and sensitive biomarkers have been identified making detection of AI elusive. Organ-specific autoimmune disease gets treated using established protocols without sufficient consideration for fertility of women. Detection of AAbs mandates management of endometriosis, POI and other idiopathic infertility as an autoimmune disease with the treatment having adverse effects. This chapter will focus on AI, briefly in males but mainly in females, to

1. autoantigenic targets identified in female infertility with special emphasis on endometri-

Sperm are specialized haploid cells with autoantigenic and isoantigenic potential. Thus, ASA can be present in blood, semen, follicular fluid and cervicovaginal secretions affecting sperm movement, capacitation, fertilization and embryo implantation [13, 14]. ASA are far more

In testis, the Sertoli cells through tight junctions form the impervious blood-testis barrier of two compartments: basal and adluminal. Basal compartment, which houses spermatogonia and young spermatocytes, is connected to vasculature through phagocytic Sertoli cells, which in turn act as antigen presenting cells to induce tolerance. The adluminal surface housing sperm undergoing meiosis and spermiogenesis is segregated from vasculature. Thus leakage of autoantigens from basal compartment can potentially generate ASAs. However, the exact mechanism of ASA generation is still unclear [13]. In some cases, Human Leucocyte Antigen system is associated with ASA and AI [15]. In 0.9–4% of normal fertile adult males as well as pre-pubertal boys, ASA are found in blood serum, seminal plasma, or directly attached to sperm surface indicating these to be NAbs generating confusion on their role in human

2. current understanding of effect of autoantibodies using animal models of disease,

2. Male autoimmune infertility: anti-sperm antibodies (ASA)

3. including (AAbs) as diagnostic tools: current practices and

abortions and may also have presence of multiple autoantibodies (AAbs) [7–11].

include:

osis and POI,

38 Autoantibodies and Cytokines

4. future research.

infertility [16, 17].

frequent than oocyte antibodies.

ASA could be against carbohydrate moieties and sperm antigens example integral membrane proteins (exposed due to undescended testes) mainly through molecular mimicry. Natural ASA are reported in rodents due to sperm antigenic 'leak' to ensure immune tolerance. ASA are generally associated with genital tract infections. Vasectomy induces AAbs to antigens of mature human sperm [20, 21] with HLABw22 and A28 having increased predisposition post vasectomy [22]. Incidence reported is 61% pre- and 73–80% post-vasectomy. Antigens could be of either testicular or epididymal origin (epididymal maturation) with Abs directed to acrosome, equatorial and postacrosomal regions, tail midpiece and sperm nucleus. This could be due to sperm leakage in either the vas or cauda epididymis [21]. AutoAbs to FA-1 antigen (44%) and protamine (28%) seen post vasectomy in sera (none in seminal plasma) with prevalence of reduced fertilization rate in vitro. These were either of IgG, M or A subclass [23]. Post vasectomy ASA are seen only in serum while in seminal plasma and ejaculate post vasovasostomy. Fertile men with no ASA before vasovasostomy will show ASA that can affect sperm count [24, 25]. Further, there is no overlap of ASA between infertile men, post vasectomy [26] and post vasovasostomy. However, there are conflicting reports on their influence on pregnancy rate [27, 28]. Table 1 enlists ASA in men with autoimmune infertility.

High titers of IgA-ASA found in seminal plasma of infertile men bind sperm head and impair fertilizing ability, the IgG elicit opsonization, and IgM from vaginal washings of vaginitis cases reduce fertilization by 44% [13]. ASAs directed to surface antigens are clinically relevant since they affect semen quality (not morphology or count) by any one of: premature acrosome reaction making the sperm moribund, sperm agglutination leading to impairment in cervical mucus penetration, opsonization through female genital tract via complement pathway.

ASA may aid sperm capacitation with no adverse effects on sperm-oocyte fusion. However, ASA binding outer acrosomal membrane proteins are washed away during procedure and do not affect IVF-intracytoplasmic sperm injection (IVF-ICSI) outcomes unlike those in females which are reported to reduce cleavage rate [47–49], with multiple autoantigenic targets necessary for AI [50].

Typically in women, the mucosal immunity protects entire reproductive tract up to Fallopian tubes against incoming sperm or any microbes. Thus vaginal and cervical secretions may contain ASA due to multiple semen exposures causing autoantigenicity to seminal fluid proteins. In rare cases of Human Seminal Plasma Allergy, first exposure can elicit antibodies [51] though it is not always associated with infertility [52, 53].


protected by circulating macrophages and NK cells that clear the incoming sperm. Thus sperm coated with IgA-ASA are unaffected unlike those by IgG which are opsonized and cleared via macrophages. Both subtypes in the mucus individually affect fertilization alone while a com-

Autoantibodies: Key Mediators of Autoimmune Infertility

http://dx.doi.org/10.5772/intechopen.73899

41

IgA alloantibodies to FSH are seen in some normal fertile women and can be produced during tolerance to partner antigens (sperm proteins and shared maternal antigens) through semen [59, 60]. Patients with increased intestinal permeability in bowel inflammatory disease show higher production of ASA through molecular mimicry or epitope sharing between intestinal microbes and spermatozoa [61]. An upregulated normal mucosal immune response could lead to the elevated levels of anti-FSH IgA antibodies in IVF patients. Another possible explanation could be a deficit in producing antibodies that neutralize anti-FSH immunoglobulins, which has been noted in patients who produce ASA [62]. These results together suggest that the elevated values of anti-FSH IgA in IVF patients could represent a failure in mucosal tolerance in the genital tract, which could be genetically determined [12] (Table 2). Enlists ASA detected

Presence of ASA in serum of seminal fluid binding to sperm outer membrane antigens and thereby altering fertilization rate are relevant, is inversely correlated with pregnancy and not a good indicator of pregnancy outcome. Testing for ASA is indicated for men with genitourinary infections (e.g., Chlamydia) or acquired genital tract obstructions. Nevertheless, these ASA

Sexually active homosexual individuals who have also undergone pelvic surgery should be advised to test for ASA [69]. Routine semen samples can be tested for sperm bound antibodies by IgG-mixed antiglobulin reaction (IgG-MAR [70]), immunobead test (IBT) [71] or sperm-MAR test [72]. However, none of the available diagnostic tests quantitate, are neither effective nor specific [73, 74]. Hence, instead of ineffective generalized immunosuppressive therapy

Post vasovasostomy couples are advised IVF for pregnancy depending on body mass index and age which affect serum testosterone levels as well as ASA in men. In these cases, IVF may be beneficial only after testing for hypogonadism and serum testosterone levels [80]. ASA post

ASA Body fluid compartment Function Reference 80 kDa protein Serum – [63, 64] BS 17 – [65] rSMP-B – – [66] Acrosin Serum Sperm-oocyte interaction [67] H-Y antigen Secondary recurrent miscarriage [68]

2.1. Diagnostic approaches and treatment modalities for couples with ASA

bination significantly affects fertilization rate [55–58].

in sera of women.

may not always hinder pregnancy.

IVF-ICSI should be considered [75–79].

Table 2. List of autoantigenic targets against sera of women with ASA.

Table 1. List of autoantigens in men with autoimmune infertility.

ASA in females are of IgG, IgA and IgE subtypes in blood, lymph and cervical-vaginal mucus [50]. IgA antibodies in the cervical secretions can bind and agglutinate sperm with eventual clearance by circulating macrophages while the predominant IgG [54] can lead to opsonization and local clearance of antibody-antigen complexes. The uterus and Fallopian tubes are also protected by circulating macrophages and NK cells that clear the incoming sperm. Thus sperm coated with IgA-ASA are unaffected unlike those by IgG which are opsonized and cleared via macrophages. Both subtypes in the mucus individually affect fertilization alone while a combination significantly affects fertilization rate [55–58].

IgA alloantibodies to FSH are seen in some normal fertile women and can be produced during tolerance to partner antigens (sperm proteins and shared maternal antigens) through semen [59, 60]. Patients with increased intestinal permeability in bowel inflammatory disease show higher production of ASA through molecular mimicry or epitope sharing between intestinal microbes and spermatozoa [61]. An upregulated normal mucosal immune response could lead to the elevated levels of anti-FSH IgA antibodies in IVF patients. Another possible explanation could be a deficit in producing antibodies that neutralize anti-FSH immunoglobulins, which has been noted in patients who produce ASA [62]. These results together suggest that the elevated values of anti-FSH IgA in IVF patients could represent a failure in mucosal tolerance in the genital tract, which could be genetically determined [12] (Table 2). Enlists ASA detected in sera of women.

### 2.1. Diagnostic approaches and treatment modalities for couples with ASA

Presence of ASA in serum of seminal fluid binding to sperm outer membrane antigens and thereby altering fertilization rate are relevant, is inversely correlated with pregnancy and not a good indicator of pregnancy outcome. Testing for ASA is indicated for men with genitourinary infections (e.g., Chlamydia) or acquired genital tract obstructions. Nevertheless, these ASA may not always hinder pregnancy.

Sexually active homosexual individuals who have also undergone pelvic surgery should be advised to test for ASA [69]. Routine semen samples can be tested for sperm bound antibodies by IgG-mixed antiglobulin reaction (IgG-MAR [70]), immunobead test (IBT) [71] or sperm-MAR test [72]. However, none of the available diagnostic tests quantitate, are neither effective nor specific [73, 74]. Hence, instead of ineffective generalized immunosuppressive therapy IVF-ICSI should be considered [75–79].

Post vasovasostomy couples are advised IVF for pregnancy depending on body mass index and age which affect serum testosterone levels as well as ASA in men. In these cases, IVF may be beneficial only after testing for hypogonadism and serum testosterone levels [80]. ASA post


Table 2. List of autoantigenic targets against sera of women with ASA.

ASA in females are of IgG, IgA and IgE subtypes in blood, lymph and cervical-vaginal mucus [50]. IgA antibodies in the cervical secretions can bind and agglutinate sperm with eventual clearance by circulating macrophages while the predominant IgG [54] can lead to opsonization and local clearance of antibody-antigen complexes. The uterus and Fallopian tubes are also

Autoantigen Body fluid

DNA polymerase Seminal

Rab GDP-dissociation inhibitor beta – Elongation factor 2 –

GAPDH-2 – L-Lactate dehydrogenase C chain – ATP synthase beta chain mitochondrial precursor –

CRISP-2 –

Table 1. List of autoantigens in men with autoimmune infertility.

Proacrosin binding protein sp32 Seminal

Nuclear autoantigenic sperm protein (NASP)

Human G-phosphogluconate dehydrogenase,

histone binding

40 Autoantibodies and Cytokines

decarboxylating

compartment

Protamines Serum – [30]

plasma

HSP70, 70-2 and 90 Serum Acrosome reaction [26] Disulfide isomerase ER60 – – [26] Sperm agglutination antigen-1 (SAGA-1) – – [33] Alpha enolase Serum – [34]

plasma

ESP Serum Intra-acrosomal [35] SAMP 32 [36, 37] SAMP14/ PH-20/hyaluronidase [38] AKAP 3 Fibrous sheath of the principal piece of

CABYR [40–42]

FSP95 Fibrous sheath antigen [44] SLLP1 Intra-acrosomal protein [44] Zona pellucida [8] FSH [45] hESP Serum Sperm-egg binding and fusion [46]

RSP44 A radial spoke protein present in the

YLP 12 peptide Serum acrosome reaction, union of sperm-

Function Reference

– [31]

[32]

[39]

[43]

Serum Lowers fertilization rate [29]

oocyte

–

–

the sperm tail

axonemes of both sperm tail and cilia

vasovasostomy can cause necrospermia and deteriorate sperm count hence IVF-ICSI using testicular sperm is an option [81].
