Egress of sperm autoantigen from seminiferous tubules maintains systemic tolerance.

Autoimmune responses to meiotic germ cell antigens (MGCA) that are expressed on sperm and testis occur in human infertility and after vasectomy. Many MGCA are also expressed as cancer/testis antigens (CTA) in human cancers, but the tolerance status of MGCA has not been investigated. MGCA are considered to be uniformly immunogenic and nontolerogenic, and the prevailing view posits that MGCA are sequestered behind the Sertoli cell barrier in seminiferous tubules. Here, we have shown that only some murine MGCA are sequestered. Nonsequestered MCGA (NS-MGCA) egressed from normal tubules, as evidenced by their ability to interact with systemically injected antibodies and form localized immune complexes outside the Sertoli cell barrier. NS-MGCA derived from cell fragments that were discarded by spermatids during spermiation. They egressed as cargo in residual bodies and maintained Treg-dependent physiological tolerance. In contrast, sequestered MGCA (S-MGCA) were undetectable in residual bodies and were nontolerogenic. Unlike postvasectomy autoantibodies, which have been shown to mainly target S-MGCA, autoantibodies produced by normal mice with transient Treg depletion that developed autoimmune orchitis exclusively targeted NS-MGCA. We conclude that spermiation, a physiological checkpoint in spermatogenesis, determines the egress and tolerogenicity of MGCA. Our findings will affect target antigen selection in testis and sperm autoimmunity and the immune responses to CTA in male cancer patients.

Autoimmune epididymoorchitis is essential to the pathogenesis of male-specific spondylarthritis in HLA-B27-transgenic rats.

OBJECTIVE: Male rats transgenic for HLA-B27 and human ß(2) -microglobulin (hß(2) m) spontaneously develop epididymoorchitis (EO) preceding the development of spondylarthritis (SpA). In the specific B27/hß(2) m-transgenic rat cross-strain (21-3 × 382-2)F(1) , only the males develop SpA, and neither sex develops gut inflammation. This study was undertaken to determine whether EO and SpA in male (21-3 × 382-2)F(1) rats are causally related. In addition, the primary characteristics of EO in this rat arthritis model were assessed. METHODS: Male B27/hß(2) m-transgenic (21-3 × 382-2)F(1) rats underwent bilateral, unilateral, or sham epididymoorchiectomy between ages 36 and 125 days. The castrated rats were given testosterone replacement. Alternatively, the 21-3 and 283-2 transgene loci were crossed with a transgene inducing aspermatogenesis. Rats were observed for the development of EO, arthritis, and spondylitis. RESULTS: In unmanipulated transgenic rats, inflammation was first evident in the ductuli efferentes (DE; ducts linking the rete testis to epididymis) as early as age 30 days. The inflammation was initially neutrophilic, and later became granulomatous. Antisperm and anti-testis cell antibodies appeared in the rat serum after age 70 days. Cells infiltrating the testes were predominantly CD4+ T cells and CD68+ or CD163+ macrophages. Quantitative polymerase chain reaction of the DE, epididymis, and testis showed elevations in the levels of interferon-γ, interleukin-10 (IL-10), and IL-17A. In addition, levels of IL-12A, IL-22, IL-23A, and IL-23 receptor were found to be elevated in the DE. Remarkably, castration of the rats before age 91 days completely prevented the subsequent onset of arthritis and spondylitis, as did transgene-induced azospermia. CONCLUSION: Autoimmune EO develops spontaneously in HLA-B27/hß(2) m-transgenic (21-3 × 283-2)F(1) rats at age 30 days, the age when antigen-positive meiotic germ cells first exit the testis. Persistent testicular inflammation and/or antigenic stimulation are essential prerequisites for the subsequent development of SpA. Thus, dysregulated innate immunity at immune-privileged sites may be an essential mechanism triggering the onset of SpA.

Regulatory T cells control tolerogenic versus autoimmune response to sperm in vasectomy.

Vasectomy is a well accepted global contraceptive approach frequently associated with epididymal granuloma and sperm autoantibody formation. To understand the long-term sequelae of vasectomy, we investigated the early immune response in vasectomized mice. Vasectomy leads to rapid epithelial cell apoptosis and necrosis, persistent inflammation, and sperm granuloma formation in the epididymis. Vasectomized B6AF1 mice did not mount autoimmune response but instead developed sperm antigen-specific tolerance, documented as resistance to immunization-induced experimental autoimmune orchitis (EAO) but not experimental autoimmune encephalomyelitis. Strikingly, tolerance switches over to pathologic autoimmune state following concomitant CD4(+)CD25(+)Foxp3(+) regulatory T cell (Treg) depletion: unilaterally vasectomized mice produce dominant autoantibodies to an orchitogenic antigen (zonadhesin), and develop CD4 T-cell- and antibody-dependent bilateral autoimmune orchitis. Therefore, (i) Treg normally prevents spontaneous organ-specific autoimmunity induction by persistent endogenous danger signal, and (ii) autoantigenic stimulation with sterile autoinflammation can lead to tolerance. Finally, postvasectomy tolerance occurs in B6AF1, C57BL/6, and A/J strains. However, C57BL/6 mice resisted EAO after 60% Treg depletion, but developed EAO after 97% Treg reduction. Therefore, variance in intrinsic Treg function--a possible genetic trait--can influence the divergent tolerogenic versus autoimmune response to vasectomy.

The postnatal maternal environment affects autoimmune disease susceptibility in A/J mice.

The postnatal maternal environment is known to increase susceptibility to a number of autoimmune diseases. Here we asked whether the postnatal maternal environment could influence autoimmune disease development to day 3 thymectomy (d3tx)-induced autoimmune ovarian disease (AOD) and experimental allergic encephalomyelitis (EAE) in cross-fostered A/J and B6 mice. A/J pups foster-nursed by B6 mothers exhibit an increase in autoimmune disease development while cross-fostering B6 pups on A/J mothers did not alter their susceptibility. The increase in AOD incidence seen in foster-nursed d3tx A/J mice correlated with a decrease in the total number of CD4(+) T cells in the lymph nodes of these animals. Analysis of the cellular composition in the milk revealed that B6 mice shed significantly more maternally derived lymphocytes into their milk compared to A/J mothers. These data suggest that there are maternally derived postnatal factors that influence the development of autoimmune disease in A/J mice.

Cutting edge: normal regional lymph node enrichment of antigen-specific regulatory T cells with autoimmune disease-suppressive capacity.

Natural CD4(+)CD25(+)Foxp3(+) regulatory T cells (Treg) effectively prevent autoimmune disease development, but their role in maintaining physiological tolerance against self-Ag of internal organs is not yet defined. In this study, we quantified disease-specific Treg (DS-Treg) as Treg that preferentially suppress one autoimmune disease over another in day 3 thymectomized recipients. A striking difference was found among individual lymph nodes (LN) of normal mice; Treg from draining LN were 15-50 times more efficient than those of nondraining LN at suppressing autoimmune diseases of ovary, prostate, and lacrimal glands. The difference disappeared upon auto-Ag ablation and returned upon auto-Ag re-expression. In contrast, the CD4(+)CD25(-) effector T cells from different individual LN induced multiorgan inflammation with comparable organ distribution. We propose that peripheral tolerance for internal organs relies on the control of autoreactive effector T cells by strategic enrichment of Ag-specific Treg in the regional LN.

Physiologic self antigens rapidly capacitate autoimmune disease-specific polyclonal CD4+ CD25+ regulatory T cells.

Studies on CD4+ CD25+ regulatory T cells (Tregs) with transgenic T-cell receptors indicate that Tregs may receive continuous antigen (Ag) stimulation in the periphery. However, the consequence of this Ag encounter and its relevance to physiologic polyclonal Treg function are not established. In autoimmune prostatitis (EAP) of the day-3 thymectomized (d3tx) mice, male Tregs suppressed EAP 3 times better than Tregs from female mice or male mice without prostates. Importantly, the superior EAP-suppressing function was acquired after a 6-day exposure to prostate Ag in the periphery, unaffected by sex hormones. Thus, a brief exposure of physiologic prostate Ag capacitates peripheral polyclonal Tregs to suppress EAP. In striking contrast, autoimmune ovarian disease (AOD) was suppressed equally by male and female Tregs. We now provide evidence that the ovarian Ag develops at birth, 14 days earlier than prostate Ag, and that male Tregs respond to neonatal ovarian Ag in the Treg recipients to gain AOD-suppressing capacity. When d3tx female recipients were deprived of ovarian Ag in the neonatal period, AOD was suppressed by female but not by male Tregs, whereas dacryoadenitis was suppressed by both. We conclude that the physiologic autoAg quickly and continuously enhances disease-specific polyclonal Treg function to maintain self-tolerance.

Failure of CD25+ T cells from lupus-prone mice to suppress lupus glomerulonephritis and sialoadenitis.

The development of organ-specific autoimmune diseases in mice thymectomized on day 3 of life (d3tx mice) can be prevented by transferring CD4(+)CD25(+) T cells from syngeneic, normal adult mice. Using a d3tx model, we asked whether CD4(+)CD25(+) T cell deficiency contributes to glomerulonephritis (GN) in lupus-prone mice. New Zealand Mixed 2328 (NZM2328) mice spontaneously develop autoantibodies to dsDNA and female-dominant, fatal GN. After d3tx, both male and female NZM2328 mice developed 1) accelerated dsDNA autoantibody response, 2) early onset and severe proliferative GN with massive mesangial immune complexes, and 3) autoimmune disease of the thyroid, lacrimal gland, and salivary gland. The d3tx male mice also developed autoimmune prostatitis. The transfer of CD25(+) cells from 6-wk-old asymptomatic NZM2328 donors effectively suppressed dsDNA autoantibody and the development of autoimmune diseases, with the exception of proliferative lupus GN and sialoadenitis. This finding indicates that NZM2328 lupus mice have a selective deficiency in T cells that regulates the development of lupus GN and sialoadenitis. After d3tx, the proliferative GN of female mice progressed to fatal GN, but largely regressed in the male, thereby revealing a checkpoint in lupus GN progression that depends on gender.

Aod1 controlling day 3 thymectomy-induced autoimmune ovarian dysgenesis in mice encompasses two linked quantitative trait loci with opposing allelic effects on disease susceptibility.

Day 3 thymectomy (D3Tx) leads to a paucity of CD4(+)CD25(+) suppressor T cells, a loss of peripheral tolerance, and the development of organ-specific autoimmune disease in adult mice. Importantly, D3Tx does not lead to autoimmune disease in all mouse strains, indicating that this process is genetically controlled. Previously, we reported linkage of D3Tx-induced autoimmune ovarian dysgenesis (AOD) and its intermediate phenotypes, antiovarian autoantibody responsiveness, oophoritis, and atrophy, to five quantitative trait loci (QTL), designated Aod1 through Aod5. We also showed interaction between these QTL and H2 as well as Gasa2, a QTL controlling susceptibility to D3Tx-induced autoimmune gastritis. To physically map Aod1, interval-specific bidirectional recombinant congenic strains of mice were generated and studied for susceptibility to D3Tx-induced AOD. Congenic mapping studies revealed that Aod1 controls susceptibility to oophoritis and comprises two linked QTL with opposing allelic effects. Aod1a resides between D16Mit211 (23.3 cM) and D16Mit51 (66.75 cM) on chromosome 16. Aod1b maps proximal of Aod1a between D16Mit89 (20.9 cM) and D16Mit211 (23.3 cM) and includes the candidate genes stefin A1, A2, and A3 (Stfa1-Stfa3), inhibitors of cathepsin S, a cysteine protease required for autoantigen presentation, and the development of autoimmune disease of the salivary and lacrimal glands following D3Tx. cDNA sequencing revealed the existence of structural polymorphisms for both Stfa1 and Stfa2. Given the roles of cathepsins in Ag processing and presentation, Stfa1 and Stfa2 alleles have the potential to control susceptibility to autoimmune disease at the level of both CD4(+)CD25(+) suppressor and CD4(+)CD25(-) effector T cells.

CD40 ligand in pathogenesis of autoimmune ovarian disease of day 3-thymectomized mice: implication for CD40 ligand antibody therapy.

The blockade of CD40 ligand (CD40L) is effective in autoimmune disease prevention. Recently, a brief period of CD40L mAb treatment was reported to induce tolerance and enhancement of CD4(+)CD25(+) regulatory T cell activity. We therefore determined the efficacy of CD40L mAb treatment in autoimmunity that resulted from CD4(+)CD25(+) regulatory T cell deficiency. Autoimmune ovarian disease (AOD) and oocyte autoantibody response of day 3-thymectomized (d3tx) mice were inhibited by continuous CD40L mAb treatment from day 3, or from days 10-14, whereas CD40L mAb treatment confined to the neonatal week was ineffective. The enhanced expression of memory markers (CD44 and CD62L(low)) on CD4(+) T cells of the d3tx mice was unaffected by CD40L mAb treatment. In contrast, their increased T cell activation markers (CD69 and CD25) were eliminated by CD40L mAb treatment. Moreover, ex vivo activated T cells of d3tx mice expressed elevated intracellular IFN-gamma, and this was also blocked by CD40L mAb. The memory T cells, although nonpathogenic in CD40L mAb-positive environment, transferred severe AOD to CD40L mAb(-) neonatal recipients. Most importantly, CD40L mAb treatment inhibited AOD in recipients of T cells from d3tx donors with severe AOD and led to regression of AOD in d3tx mice documented at 4 wk. Therefore, 1) the continuous presence of CD40L mAb both prevents and causes regression of AOD in the d3tx mice; and 2) the multiple steps of the d3tx autoimmune disease, including T cell activation, cytokine production, T cell-mediated inflammation, and tissue injury, are CD40L dependent.

Differential effect of neonatal thymectomy on systemic and organ-specific autoimmune disease.

Thymectomy on day 3 after birth (d3tx) depletes CD4+CD25+ regulatory T cells leading to multiple independent organ-specific autoimmune diseases. However, systemic autoimmune disease such as systemic lupus erythematosus has not been reported in d3tx mice. Herein, we investigate the effect of d3tx on spontaneous autoantibody response and immune complex glomerulonephritis (GN) in the lupus-prone (SWR x NZB)F1 (SNF1) mice. The d3tx SNF1 mice developed accelerated antibody responses to double-stranded DNA and DNA-histone complexes, and an increased frequency of activated CD4+ T cells. Unexpectedly, the renal histopathology and mortality from GN were significantly ameliorated in d3tx SNF1 mice, which concomitantly exhibited a Th2-biased antibody response. By 16 weeks, the d3tx mice had higher levels of total and autoantigen-specific IgG1, and at 12 months, the autoantigen-specific IgG2a was significantly below that of the sham thymectomized mice. These differences corresponded with reduction in total and autoantigen-specific IgG2a in the renal eluates of the d3tx mice. In addition, while all the mice had immune complex deposition in the mesangium and peripheral capillary loops of the glomeruli, IgG2a and C3 deposits restricted to the mesangial regions alone were more frequent in d3tx mice. D3tx SNF1 mice, protected from lupus-like GN, developed organ-specific autoimmune responses and diseases including prostatitis, orchitis and oophoritis, and antibodies to prostate, cardiac and skeletal muscle antigens. Therefore, d3tx paradoxically protects SNF1 mice from genetically prone lupus-like GN, yet promotes de novo organ-specific autoimmunity.

Induction and immunohistology of autoimmune ovarian disease in cynomolgus macaques (Macaca fascicularis).

Autoimmune ovarian disease (AOD) is a probable cause of human premature ovarian failure, and a potential complication of contraceptive vaccines based on ovarian antigens. The diagnosis depends on detection of noninfectious ovarian inflammation (oophoritis) and serum antibody to ovarian and placental antigens. Mechanisms underlying AOD have been investigated in mice but not in primates. Herein, we report induction of AOD in primates, and compare the immunopathology between monkey and murine AOD. Four cynomolgus macaques immunized with monkey or human zona pellucida 3 peptide (pZP3) in adjuvant, developed T-cell responses to the immunizing peptide and produced antibody that bound to native zona pellucida in vivo. Immunostaining of ovaries from pZP3-immunized macaques showed numerous clusters of T cells co-localized with major histocompatibility complex II-positive macrophages in the ovarian interstitium. Such foci were not detected in untreated or adjuvant-treated control monkeys. This finding is comparable to murine pZP3-induced AOD. However, unlike murine AOD in which numerous granulomatous lesions are detected, severe granulomatous inflammation was detected in only one of three monkeys with abnormal immunohistology. Similar to mice with pZP3-induced AOD, the immunized monkeys retained normal ovarian function. The results are discussed in the context of complications of ZP-based human immunocontraceptive vaccines and case reports of human autoimmune oophoritis.