Immunological phenomena observed in the testis and their possible role in infertility

Hypertension and reproductive dysfunction: a possible role of inflammation and inflammation-associated lymphangiogenesis in gonads

Hypertension is one of the most prevalent diseases that leads to end organ damage especially affecting the heart, kidney, brain, and eyes. Numerous studies have evaluated the association between hypertension and impaired sexual health, in both men and women. The detrimental effects of hypertension in men includes erectile dysfunction, decrease in semen volume, sperm count and motility, and abnormal sperm morphology. Similarly, hypertensive females exhibit decreased vaginal lubrication, reduced orgasm, and several complications in pregnancy leading to fetal and maternal morbidity and mortality. The adverse effect of hypertension on male and female fertility is attributed to hormonal imbalance and changes in the gonadal vasculature. However, mechanistic studies investigating the impact of hypertension on gonads in more detail on a molecular basis remain scarce. Hence, the aim of the current review is to address and summarize the effects of hypertension on reproductive health, and highlight the importance of research on the effects of hypertension on gonadal inflammation and lymphatics.

Perspective in Pediatric Pathology, Chapter 24. Testicular Inflammatory Processes in Pediatric Patients

Acute scrotal pain in children represents a major diagnostic and therapeutic challenge. An important initial differentiation should be made between epididymitis and other processes that cause acute scrotal pain, such as testicular torsion and tumor. Infectious agents disseminating through the blood flow can damage the testis by causing orchitis. On the other hand, infections ascending via spermatic pathways typically lead to epididymitis [ 1 ].

Tissue microcircumstances for leukocytic infiltration into the testis and epididymis in mice

Spermatozoa do not appear in the seminiferous epithelium until puberty, when immune tolerance has already been established. Therefore, they contain various autoimmunogenic materials which are recognized as foreign by the self immune system. However, the testis and epididymis are known as immunologically privileged organs. In particular, the blood-testis barrier (BTB) formed by Sertoli cells and the blood-epididymal barrier formed by epididymal epithelial cells protect autoimmunogeneic spermatozoa from attack by the self immune system. The immune privileged circumstances in the testis and epididymis have been demonstrated by many studies to involve a local transplantation system. We review here the immune privileged status of these organs from the viewpoint of induction of inflammatory cell responses in mice. The testicular interstitium in mice is resistant to vasculitis, lymphangitis, spermatic granuloma and polymorphonuclear cell infiltration: however, the epididymal interstitium is vulnerable to them. Therefore, the testicular tissue outside BTB is also protected from inflammatory cell infiltration, although many resident macrophages are normally present in the testis. In sharp contrast, subcutaneous injection of viable syngeneic testicular germ cells (TGC) alone induces autoimmune orchitis with no involvement of the epididymitis in mice. In the testes of TGC-immunized animals, severe lymphocytic infiltration with aspermatogenesis was seen in spite of no use of adjuvants. Unexpectedly, injections of viable epididymal spermatozoa (ES) did not evoke any autoimmune inflammation in the epididymides. Therefore, the testis rather than the epididymis may easily become an unprivileged organ as to autoimmunity under some special conditions.

cDNA cloning and characterization of a human sperm antigen (SPAG6) with homology to the product of the Chlamydomonas PF16 locus

Serum from an infertile male with high-titer anti-sperm antibodies was used to identify a novel human sperm antigen by screening of a testis expression library. The clone, initially designated Repro-SA-1 (HUGO-approved symbol SPAG6), was found to encode a sequence highly enriched in testis. The deduced amino acid sequence of the full-length cDNA revealed striking homology to the product of the Chlamydomonas reinhardtii PF16 locus, which encodes a protein localized to the central pair of the flagellar axoneme. The human gene encodes 1.8- and 2.8-kb mRNAs highly expressed in testis but not in prostate, ovary, spleen, thymus, small intestine, colon, peripheral blood leukocytes, heart, brain, placenta, liver, muscle, kidney, and pancreas. The gene was mapped to chromosome 10p11.2-p12. Antibodies raised against SPAG6 sequences localized the protein to the tails of permeabilized human sperm. Both the Chlamydomonas protein and SPAG6 contain eight contiguous armadillo repeats, which place them in a family of proteins known to mediate protein-protein interactions. The cloning of the human homologue of the Chlamydomonas PF16 locus provides a new avenue to explore the role of the axoneme central pair in human sperm function.

Testicular biopsy. Contemporary interpretation

Biopsy of the testis is not universally accepted in contrast with biopsies of other organs. The pathologist studies and reports on the pathophysiology of the testicular biopsy specimen. Methodology requires the inclusion of qualitative and quantitative studies, the evaluation of the lesion's evolution (prognosis), and, often, therapeutic advice regarding treatment. Cooperation between pathologists and clinicians optimizes the utility of the biopsy for the patient.

Testicular circulatory isolation: not a cause of immune-mediated testis injury in the rat

BACKGROUND

Testicular circulatory isolation (TCI), a regional drug exclusion approach designed to prevent chemotherapy-induced male infertility, can reduce testicular drug exposure and preserve fertility. The immunological sequelae of this surgical procedure were investigated.

METHODS

Forty Sprague-Dawley rats received unilateral TCI for 45 min and were killed at intervals of up to 43 days later. Testicular histology was evaluated qualitatively using hematoxylin and eosin stain, a direct immunofluorescent technique for detection of antigen-antibody complexes, and an indirect immunofluorescent technique to detect circulating antitestis antibodies.

RESULTS

No immune-mediated injury was evident up to 43 days after TCI.

CONCLUSION

The current work, taken together with previously published data, indicate that TCI produces no immunological damage in the rat testis. Because TCI is well tolerated in humans, this work also supports the institution of human clinical trials of this technique in men about to receive fertility-threatening chemotherapy.

Experimental allergic orchitis in mice. VII. Preliminary characterization of the aspermatogenic autoantigens responsible for eliciting actively and passively induced disease

Experimental allergic orchitis (EAO) can be induced actively and passively in mice by either immunization with mouse testicular homogenate (MTH) in conjunction with the appropriate adjuvants or by transferring CD4+ T cells isolated from sensitized donors into non-immunized, naive recipients. The distribution of inflammatory lesions seen in active and passive EAO are markedly different. In active EAO maximal disease is observed in the seminiferous tubules, whereas in passive EAO lesions occur primarily in the straight tubules, rete testis, and ductus efferentes. These observations suggest that different immunopathogenic mechanisms and/or aspermatogenic autoantigens may be responsible for the distinct histopathologic profiles. Two murine testis-specific aspermatogenic autoantigens (mAP1 and mAP2) were partially purified from MT acetone powder by extraction in 7-M urea under reducing conditions, gel filtration, ion-exchange chromatography, and preparative isoelectric focusing from pH 3 to 10. In gel filtration on Sephacryl S-400 in 7-M urea, mAP1 is confined to the V0 peak, while mAP2 is in the major included peak. mAP1 has an isoelectric point of 4.4-4.9, is sensitive to both pronase and DNase but not RNase, and is active at a minimal dose of 250-500 micrograms (dry wt). Dose-response bioassays for active and passive EAO revealed that mAP1 preferentially elicits active disease, whereas mAP2 is most effective at eliciting passive disease. These results support the concept that the different histopathologic profiles seen in active and passive EAO are, in part, the result of different immunopathologic responses elicited by separate aspermatogenic autoantigens.

Identification of 2 stallion sperm-specific proteins and their autoantibody response

In this study, 2 stallions were immunised with their own spermatozoa to ascertain whether an antisperm autoantibody response could be mounted. The results demonstrated that the stallion can recognise and respond to sperm autoantigens by producing circulating antisperm antibodies, primarily of the IgG class. Such autoantibodies appeared 2-4 weeks after inoculation and persisted for 6-20 weeks. Immunochemical characterisation by western blot identified two major sperm autoantigens, with molecular weights of 70 kD and 62 kD. Control pony stallions immunised with adjuvants alone failed to exhibit such antibodies. IgA antisperm antibodies were measurable in seminal plasma of both stallions. We suggest that, as in other species, autoimmunity to spermatozoa may play a role in idiopathic subfertility in stallions.

Immunohistological localization of autoantigens detected by serum autoantibodies from mice with experimental autoimmune orchitis without using adjuvants

Recently, a murine model of testicular autoimmunity was produced in mice by subcutaneous injections with viable syngeneic testicular germ cells alone, without depending on the use of any adjuvants or immunopotentiators. In this article, histological localization of autoantigens detected by circulating autoantibodies was immunohistochemically studied by reacting the immune sera with frozen sections of testes from mice of various ages. The study showed that the reactivity of immune sera was detected in the testis sections of normal mice older than 24 days of age but not in those of mice younger than 20 days of age. The immunostain was detected at proacrosomal, acrosomal, and other cytoplasmic regions of variously shaped developing spermatids but never on pachytene spermatocytes, basal compartment germ cells, or the supporting tissue of the seminiferous tubules.

New experimental model for adoptive transfer of murine autoimmune orchitis

Previous studies demonstrated that experimental autoimmune orchitis (EAO) was produced in C3H/He mice with very high incidence by subcutaneous (s.c.) injections of viable syngeneic testicular germ cells (TC), without resorting to any adjuvants or immunopotentiators. Using this EAO model, a new and simple protocol was developed for adoptive transfer of EAO. Cell donors were C3H/He mice that received s.c. injections twice with TC alone. Spleen cells from the donors were stimulated in vitro with TC, propagated in interleukin-2 containing medium, then injected i.p. to naive recipient mice. This procedure induced severe orchitis and hypospermatogenesis with or without inflammation in epididymis and vas deferens in the recipients at high incidence. Elimination of all T cells or CD4+ T cells before the transfer produced no histopathological signs in the recipients whereas that of the CD8+ T cells or B cells had no inhibitory effect on the disease transfer, indicating that the effector cells are CD4+ T cells.