Gonadotropin releasing hormone (GnRH) agonist induces down-regulation of the CD3+CD25+ lymphocyte subpopulation in peripheral blood

Effect of GnRH immunocastration on immune function in male rats

The present study aimed to reveal the effects of immunocastration on the development of the immune system in rats. Seventy rats were randomly assigned into two groups: Control (n = 35) and immunized (n = 35). Twenty-day-old rats were immunized with gonadotropin-releasing hormone (GnRH) and booster immunization was administered every two weeks (three immunizations in total). From 20-day-old rats, we collected samples every two weeks, including five immunized rats and five control rats (seven collections in total). We collected blood samples, testicles, thymuses, and spleens. The results showed that GnRH immunization increased the GnRH antibody titers and reduced the testosterone concentration (both P < 0.05). Compared with the control group, the number of CD4+CD8- cells, CD4-CD8+ cells, and CD4+CD8+ cells increased (P < 0.05) whereas the number of CD4-CD8- cells and CD4+CD25+ cells reduced in the immunized group (P < 0.05) over time. GnRH immunization also increased the relative weights of thymus and spleen (P < 0.05), serum concentrations of interleukin (IL)-2, IL-4, IL-6, IL-10, IL-17 and Interferon-γ (IFN-γ) over time (P < 0.05), and changed the mRNA levels of IL-2, IL-4, IL-6. IL-10, IL-17, IFN-γ, CD4, D8, CD19 GnRH, and GnRH receptor (GnRH-R) in thymus and spleen. Thus, GnRH immunization enhanced the immune markers in thymus, spleen, and blood immune cytokines in rats.

Activation of Gonadotropin-releasing Hormone Receptor Impedes the Immunosuppressive Activity of Decidual Regulatory T Cells via Deactivating the Mechanistic Target of Rapamycin Signaling

Understanding maternal immune tolerance is crucial for the development of therapeutics for immunological pregnancy complications. Decidual regulatory T cells (Tregs) play a pivotal role in the maintenance of maternal immune tolerance. Using a murine allogeneic pregnancy model in the current study, we identified the up-regulation of gonadotropin-releasing hormone receptor (GnRHR) in decidual T cell subsets including CD4⁺ conventional T cells, CD8⁺ T cells, and CD4⁺Foxp3⁺ Tregs. Using a lentivirus-mediated GnRHR overexpression system and a GnRHR agonist, we found that GnRHR activation decreased the expression of Treg functional molecules such as IL10 (IL-10), IL-35 subunit EBI3 (Ebi3), IL2RA (CD25), TNFRSF18 (GITR), ICOS, and Treg master regulator FOXP3. The functional analysis indicated that GnRHR activation impairs the ability of Tregs to inhibit conventional T cell proliferation. We also revealed that GnRHR activation suppressed the mechanistic target of rapamycin (mTOR) signaling in GnRHR-overexpressing splenic Tregs (Wild type C57BL/6 J background) and decidual Tregs. MHY1485, a potent mTOR activator, effectively abolished the effect of the GnRHR agonist and promoted the immunosuppressive capability of Tregs. Furthermore, in an adoptive transfer model, Treg-specific GnRHR knockdown increased Foxp3 expression in decidual Tregs while decreasing the production of IFN-γ and IL-17 in decidual effector CD4⁺ T cells and reducing the production of IFN-γ in decidual effector CD8⁺ T cells. Taken together, the present study unveils a novel mechanism by which the immunosuppressive function of decidual Tregs is modulated, and deepens our understanding of maternal immune tolerance.

Hypothalamic neurohormones and immune responses

The aim of this review is to provide a comprehensive examination of the current literature describing the neural-immune interactions, with emphasis on the most recent findings of the effects of neurohormones on immune system. Particularly, the role of hypothalamic hormones such as Thyrotropin-releasing hormone (TRH), Corticotropin-releasing hormone (CRH) and Gonadotropin-releasing hormone (GnRH). In the past few years, interest has been raised in extrapituitary actions of these neurohormones due to their receptors have been found in many non-pituitary tissues. Also, the receptors are present in immune cells, suggesting an autocrine or paracrine role within the immune system. In general, these neurohormones have been reported to exert immunomodulatory effects on cell proliferation, immune mediators release and cell function. The implications of these findings in understanding the network of hypothalamic neuropeptides and immune system are discussed.

Acute Transverse Myelitis Associated with Buserelin Use during IVF

A healthy woman undergoing in vitro fertilization (IVF) developed acute transverse myelitis (ATM) following the use of Buserelin. ATM has a multifactorial etiology and may develop as a result of the activation of immune responses. Infectious agents have been postulated as possible triggers of an immune response (Sá, 2009). Gonadotropin-releasing agonists may have a similar role and trigger the acceleration of preexisting disease by the activation of immune responses (Ho et al., 1995, and Umesaki et al., 1999).

Immunomodulatory effects of anti-estrogenic drugs

There are substantial experimental, epidemiological and clinical evidences that show that breast cancer pathology is influenced by endogenous estrogens. This knowledge is the foundation upon which endocrine deprivation therapy has been developed as a major modality for the management of breast cancer. Tamoxifen, which functions as a competitive partial agonist-inhibitor of estrogen at its receptor, has been widely used for more than three decades for adjuvant endocrine treatment in breast cancer. Currently, other effective drugs for endocrine therapy include raloxifene, different aromatase inhibitors (particularly third-generation agents) and luteinizing hormone-releasing hormone agonists. In recent years, a growing body of evidence suggests that these drugs can also act as immune modulators by altering the function of various leukocytes and the release of different cytokines. Moreover, there is evidence that anti-estrogens may prove to be beneficial in the treatment or prevention of some autoimmune diseases due to their effects on immune function. However, their immunopharmacological aspects in the present state of knowledge are not precisely comprehensible. Only a clear pathophysiological understanding could lead to an efficient strategy for breast cancer prevention and decrease in the mortality due to this disease.

Roles of prolactin and gonadotropin-releasing hormone in rheumatic diseases

PRL is capable of influencing immune responses and is a cytokine in all likelihood. Circulating PRL is elevated in a number of autoimmune diseases, and about 20% of SLE patients are hyperprolactinemic. The serum PRL concentration often does not reflect disease activity in SLE. The PRL-suppressing drug bromocriptine has been reported to benefit small numbers of patients with reactive arthritis and inflammatory eye disease, and bromocriptine may be beneficial in treating SLE. In NZB/NZW mice, bromocriptine was beneficial and prolonged life. Bromocriptine therapy favorably modified disease in human SLE. In a preliminary open-label study, SLE patients treated with bromocriptine for 6 months had significant improvement in disease activity. These responses were corroborated by masted therapeutic studies. Daily treatment with low-dose bromocriptine prevented lupus flares, and bromocriptine was as effective as hydroxychloroquine in treating active nonorgan-threatening disease. The reports of the efficacy of bromocriptine treatment of SLE are encouraging. Additional studies may confirm the findings reported in this review and may lead to further use of hormonal modification to treat lupus and other autoimmune diseases. For the present, it is important to understand that treatment with dopamine agonists such as bromocriptine is experimental and best confined to therapeutic trials. In the experience of the authors, bromocriptine should not be relied on to treat severe life-threatening autoimmune disease. If bromocriptine is used to treat SLE and is then discontinued, the patient should be observed carefully for rebound hyperprolactinemia and the development of a lupus flare. GnRH is produced by lymphocytes and exerts immunomodulatory actions. Thus, GnRH resembles a cytokine. GnRH can be shown to exert gender-restricted immune actions in vitro and in vivo. The authors' preliminary observations are consistent with the possibility that gender-related differences in expression of the GnRH receptor or in GnRH signal transducers may contribute to gender-related differences in immune responsiveness to GnRH. These differences in G proteins may contribute to the gender-related differences in immunity and expression of autoimmune disease.

Longitudinal case analysis in atopic dermatitis

The current knowledge on atopic dermatitis comes mainly from cross-sectional studies, which are not suited to establish time-courses or causal links in complex diseases. As an alternative approach, the method of longitudinal case analysis by the autoregressive integrated moving average (ARIMA) method has been introduced to investigate the pathogenesis of atopic dermatitis. The method was applied to the investigation of 2 patients suffering from severe and moderate atopic dermatitis. Disease activity, peripheral blood parameters (differential blood count, lymphocyte subpopulations, immunoglobulin E, eosinophilic cationic protein, soluble interleukin-2 receptor), mental stress and environmental factors were determined daily for 50 days. Both patients showed a positive correlation between CD4+ and CD25+ T-cells, a negative correlation between CD16/56+ natural killer cells and CD4+ T-cells, a negative correlation between eosinophils and polymorphonuclear leukocytes, and a time-shifted positive correlation of up to 2 days between scores quantifying mental stress and disease activity. A positive correlation between T-cells and polymorphonuclear leukocytes, CD4+ T-cells and the CD45RA+ subtype, as well as a negative correlation between stress and eosinophils, sports and eosinophils, and sports and disease activity were found only in one patient with more severe atopic dermatitis. In conclusion, longitudinal time-series analysis might represent an interesting and adequate method to generate and test new hypotheses on biomedical problems which cannot be addressed by cross-sectional studies.

Controlled ovarian hyperstimulation in assisted reproduction: effect on the immune system

OBJECTIVE

To determine how controlled ovarian hyperstimulation (COH) in assisted reproduction affects the immune system.

DESIGN

A prospective, nonrandomized, case-control study.

SETTING

Academic research setting.

PATIENT(S)

Women with regular menstrual cycles undergoing COH in an assisted reproduction program.

INTERVENTION(S)

Blood samples were collected in the early and late follicular phase, at the time of ovulation, and in the luteal phase during a natural cycle, and at four times during the next cycle, which included COH and IVF.

MAIN OUTCOME MEASURE(S)

Lymphocyte subpopulations and the differential blood count.

RESULT(S)

In the natural cycles, a significant increase in the total numbers of lymphocytes, B cells, natural killer cells, and CD3+HLADR+ cells was observed in the late follicular phase, whereas the T helper/T suppressor cell ratio declined. In the hyperstimulated cycles, increases were seen in the total numbers of leukocytes and neutrophils on the day of hCG administration; the number of lymphocytes, monocytes, and neutrophils was increased on the day of oocyte retrieval, and the total number of leukocytes and neutrophils increased during the luteal phase.

CONCLUSION(S)

Controlled ovarian hyperstimulation with hMG and simultaneous administration of a GnRH antagonist did not affect the immune system.

The effect of LHRH and TRH on human interferon-gamma production in vivo and in vitro

Accumulating evidence suggests that hypothalamic luteinizing hormone-releasing hormone (LHRH) and thyrotropin-releasing hormone (TRH) are two hypophysiotropic factors which modulate the immune response. The aim of the present study was to determine the in vivo effects of an intravenous bolus of LHRH and TRH on plasma interferon (IFN)-gamma production in five normoprolactinemic women with irregular menstrual cycles. We also determined prolactin (PRL), thyrotropin (TSH), follicle stimulating hormone (FSH), and luteinizing hormone (LH) levels before and after intravenous administration of LHRH and TRH. The results demonstrate that intravenous bolus of LHRH/TRH increases plasma IFN-gamma levels, with the maximum response 45 min after in vivo administration of hypothalamic peptides and after peak levels of adenohypophyseal hormones (PRL: 15 min; TSH: 30 min; FSH: 30 min; LH: 30 min). In order to investigate a possible direct action of hypothalamic hormones on immune cells, we also evaluated, in the same subjects, the influence of LHRH and TRH on IFN-gamma production by human peripheral blood mononuclear cells (PBMCs), collected before the intravenous administration of the peptides and stimulated in vitro with bacterial superantigen staphylococcal enterotoxin A (SEA) and concanavalin A (Con A). LHRH and TRH, separately and together, significantly enhanced in vitro IFN-gamma production by SEA- and ConA-activated PBMCs. The present results suggest that hypothalamic peptides (LHRH and TRH) directly, and/or indirectly pituitary hormones (PRL, TSH, FSH, and LH) or IL-2, have stimulatory effect on IFN-gamma producing cells and are further evidence of interactions between the neuroendocrine and immune systems.

Effects of LHRH-analogues on mitogenic signal transduction in cancer cells

The expression of luteinizing hormone-releasing hormone (LHRH) and its receptors has been demonstrated in a number of human malignant tumors, including cancers of the breast, ovary, endometrium and prostate. These findings suggest the presence of an autocrine regulatory system based on LHRH. Recent studies in our laboratory have demonstrated that the function of LHRH produced by ovarian cancer cells is the inhibition of their proliferation. Dose-dependent antiproliferative effects of LHRH-agonists have been observed by several laboratories in cell lines derived from the above cancers. Interestingly, also LHRH-antagonists have marked antiproliferative activity in most of the ovarian, breast and endometrial cancer cell lines tested so far, indicating that the dichotomy of LHRH-agonists/LHRH-antagonists is not valid for the LHRH-system in cancer cells. In addition, our data suggest that the classical LHRH receptor signal transduction mechanisms known from the pituitary (phospholipase-C, protein kinase C, adenylyl cyclase) are not involved in the mediation of LHRH effects in cancer cells. Data obtained by several groups, including ours, rather suggest that LHRH analogs interfere with the signal transduction of growth-factor receptors and related oncogene products associated with tyrosine-kinase activity. The mechanism of action is probably an LHRH-induced activation of a phosphotyrosine phosphatase, counteracting the effects of receptor associated tyrosine kinase. In our hands, LHRH analogs virtually blocked the EGF-induced MAP-kinase activity of ovarian and endometrial cancer cells. The pharmacological exploitation of this mechanism might provide promising new therapies for these cancers.

Pregnancy achieved by intracytoplasmic sperm injection using cryopreserved vasal-epididymal sperm from a man with spinal cord injury

Anejaculation and poor semen quality are two major causes of infertility in men with spinal cord injury (SCI). The poor motility of retrieved sperm usually has low fertilization potential and is thought to be unfavorable for cryopreservation. This report describes a pregnancy after intracytoplasmic sperm injection (ICSI) with cryopreserved vasal-epididymal sperm from a man with SCI and anejaculation. An attempt was made to obtain sperm through electroejaculation, but no motile sperm were found in two trials. Therefore, the subject underwent vasal aspiration. The retrieved sperm had a concentration of 26 x 10(6)/mL and a motility of 3%. ICSI was considered to be the best choice for the couple, but the wife did not become pregnant in the first cycle of treatment. A successful pregnancy was achieved by ICSI in the second cycle using frozen-thawed sperm, supernumerary in the previous cycle, with a density of 5 x 10(6)/mL and 1% motility. A set of healthy twins, one boy and one girl, were delivered via cesarean section at 36 weeks of gestation. Complementary to other assisted reproductive techniques, ICSI may provide men with SCI a greater opportunity to father children. The supernumerary sperm, regardless of quality, should be cryopreserved to avoid the necessity and risk of repeated assisted ejaculations and aspirations of the genital tract.

Activation status of T and NK cells in the endometrium throughout menstrual cycle and normal and abnormal early pregnancy

Endometrial lymphocytes were studied at all stages throughout the menstrual cycle and early pregnancy by flow cytometry to examine different lymphocyte subpopulations and the expression of the T- and NK-cell activation markers. After pregnancy, CD8+CD3+ lymphocytes were decreased in the decidua. In both endometrium and decidua, more T cells expressed CD69, CD71, HLA-DR, and CD38 antigens than in peripheral blood. After pregnancy, CD71+CD3+ lymphocytes were further increased. CD25+CD3+ lymphocytes decreased significantly in the endometrium and decidua of ectopic pregnancies, but not in the decidua of normal pregnancies. These findings indicate that T cells are regionally activated in the first trimester, and it may be the result of the stimulation by fetal antigens. NK cells were the most abundant cell type in the decidua, which expressed the phenotype CD16- CD56+, and CD57-CD56+. The proportion of activated decidual NK cells was increased in anembryonic pregnancies more than in normal pregnancies, although the total NK subpopulation was similar in both groups. This might result in increased NK cytotoxicity in anembryonic pregnancies. In conclusion, T cells are activated, but NK cytotoxicity is decreased in the decidua of early normal pregnancies. This might be important in the control of trophoblast growth and placental development.

Age-dependent changes in peripheral blood lymphocyte subpopulations in cattle: a longitudinal study

Immunofluorescence and flow cytometric analyses were used to study the age-dependent changes in the peripheral blood lymphocyte (PBL) subpopulations in cattle. Four healthy Holstein heifer calves (A, B, C and D), 1-2 months of age, were used in this study. Sequential peripheral blood samples were collected once a month for up to 2-2.5 years, and once at approximately 4 years of age. For the first 6 months of age, the calves had similar proportions of CD2+, CD4+, CD8+ T lymphocytes, CD20+ B lymphocytes and MHC class II+ lymphocytes. From 2 months of age up to 2-2.5 years of age, all animals had similar proportions of CD5+ cells; but during the same period, animals A and B had significantly lower proportions of WC1+ gamma delta T cells than animals C and D. After 7 months of age, however, the proportions of CD2+, CD4+ and CD8+ T cells in PBL of animals A and B significantly decreased, whereas the proportions of both CD20+ B lymphocytes and MHC class II+ lymphocytes significantly increased. In contrast, the proportions of the various PBL subpopulations in animals C and D remained virtually unchanged after 7 months of age. For the first 6 months of age, all the calves showed similar absolute counts of PBL. Thereafter, the absolute counts of PBL in animals A and B significantly increased, but remained virtually unchanged in animals C and D. Throughout the study, from 1-2 months up to 2-2.5 years of age the absolute counts of CD2+, CD4+, CD8+ and WC1+ gamma delta T cells in PBL of the four animals were not significantly different from each other. Up to 6 months of age, the CD4+/ CD8+ ratio in all calves was 2.38 +/- 0.46, but significantly decreased thereafter to 1.81 +/- 0.34. However, there were no significant differences in the CD4+/CD8+ ratios among individual animals. The increase in the absolute counts of PBL in animals A and B, after 7 months of age, was due to an increase in the absolute counts of CD5+ cells, CD20+ B lymphocytes and MHC class II+ lymphocytes. Thus, changes in the percent, but not the absolute counts of T lymphocytes, were due to high percent and absolute counts of B lymphocytes, expressing the CD5 and MHC class II antigens.

Effects of gonadotropin-releasing hormone agonist (GnRHa) and ovariectomy on leukocyte subpopulations in rats with autotransplanted endometrium

PROBLEM

To determine the effect of estrogen deficiency on populations of immune cells in rats with autotransplanted endometrium.

METHOD OF STUDY

Autologous endometrial segments were implanted in the peritoneum of rats. Leukocyte subsets in the peripheral blood (PB) and peritoneal fluid (PF) of autotransplanted rats treated with gonadotropin-releasing hormone agonist (GnRHa) or ovariectomy were analyzed by flow cytometry.

RESULTS

Endometrial growth was suppressed in association with increases in natural killer (NK) cells and macrophages in rats treated surgically or medically after endometrial implantation compared with autotransplanted-only rats. Normal rats treated with GnRHa showed no significant alterations in PB and PF leukocyte subsets, even in NK cells and macrophages, compared with untreated normal rats.

CONCLUSIONS

Data suggest that GnRHa itself did not have an immunomodulating effect when rats were treated for 3 weeks, but that a hypoestrogenic state reduced the size of the ectopic endometrium in association with increases in NK cells and macrophages. Our findings support the hypothesis that ectopic endometrial cells may release immunosuppressive factors.

The suppression of peritoneal cellular immunity in women with endometriosis could be restored after gonadotropin releasing hormone agonist treatment

PROBLEM

Our previous study reported that peritoneal natural killer (NK) cytotoxicity and CD3+CD25+ lymphocyte subpopulation were suppressed in women with advanced endometriosis. Whether these phenomena are general for all stages of endometriosis and whether these alterations could be restored by long-term use of gonadotropin releasing hormone agonist (GnRHa) are further tested in this study.

METHOD

Lymphocyte subpopulations (B cells, NK cells, T cells, and T-cell activation markers such as CD69, HLA-DR, and CD25) and NK cell cytotoxicity of peripheral blood and peritoneal fluid by dual-color flow cytometry and 51Cr release assay in 30 cases of endometriosis were compared with those in 26 controls. We also compared these changes before and after 6-month treatment with GnRHa for advanced endometriosis.

RESULTS

Compared with the controls, only those women with advanced endometriosis showed lower NK cytotoxicity in peritoneal fluid mononuclear cells (PFMC). The CD3+CD69+ lymphocyte subpopulation decreased in peripheral blood mononuclear cells (PBMC) of advanced endometriosis, while the CD3+CD25+ lymphocyte subpopulation decreased in both PBMC and PFMC of mild and advanced endometriosis. After GnRHa treatment, the CD3+CD69+ lymphocyte subpopulation increased in both PBMC and PFMC and the CD3+CD25+ lymphocyte subpopulation increased in PFMC, but not in PBMC.

CONCLUSION

Impaired local immunological function in the PF of endometriosis was confirmed by this study and the impairments could be restored after long-term GnRHa therapy.

In vivo CD3+CD25+ lymphocyte subpopulation is down-regulated without increased serum-soluble interleukin-2 receptor (sIL-2R) by gonadotropin releasing hormone agonist (GnRH-a)

PROBLEM

To test further whether the suppression of the CD3+CD25+ lymphocyte subpopulation by gonadotropin-releasing hormone agonist (GnRH-a) is related to the change in levels of cytokines and soluble interleukin-2 receptor (sIL-2R).

METHOD

Twenty-seven infertile patients were enrolled under the long protocol of GnRH-a agonist (buserelin acetate) and superovulation with gonadotropin from our IVF-ET program. Peripheral B cells, NK cells, CD4+ and CD8+ T cells and the expression of CD69, CD25, HLA-DR, and CD71 antigens on the T cells were serially examined by dual-color flow cytometry. Serum levels of cytokines and sIL-2R were measured.

RESULTS

The B cells, NK cells, T cells, CD4+, CD8+ T cells, CD3+DR+, and CD3+CD71+ lymphocyte subpopulations were not changed after the use of GnRH-a. The CD25+ T cell subpopulation was significantly down-regulated, but the CD69+ T cell subpopulation was increased when the GnRH-a was used for approximately 2 wk. The serum levels of interleukin-1 beta (IL-1 beta), interleukin-2 (IL-2), interleukin-4 (IL-4), interferon-gamma (IFN-gamma), and sIL-2R were not changed.

CONCLUSION

The GnRH-a had a transiently suppressive effect on CD25+ T cells, but a stimulatory effect on CD69+ T cells. However, the serum level of cytokines or sIL-2R did not change. These immunological modulations seems to be the result of interaction between GnRH-a and estrogen.