Gonadotropin-releasing hormone agonist influences absolute levels of lymphocyte subsets in vivo in male mice

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.

End-Stage Renal Disease-Related Accelerated Immune Senescence: Is Rejuvenation of the Immune System a Therapeutic Goal?

End-stage renal disease (ESRD) patients exhibit clinical features of premature ageing, including frailty, cardiovascular disease, and muscle wasting. Accelerated ageing also concerns the immune system. Patients with ESRD have both immune senescence and chronic inflammation that are resumed in the so-called inflammaging syndrome. Immune senescence is particularly characterised by premature loss of thymic function that is associated with hyporesponsiveness to vaccines, susceptibility to infections, and death. ESRD-related chronic inflammation has multiple causes and participates to accelerated cardiovascular disease. Although, both characterisation of immune senescence and its consequences are relatively well-known, mechanisms are more uncertain. However, prevention of immune senescence/inflammation or/and rejuvenation of the immune system are major goal to ameliorate clinical outcomes of ESRD patients.

Effect of GnRHa on Th17/Treg cells in peripheral blood of patients with unexplained repeated implantation failure

OBJECTIVE

To investigate the effect and possible mechanism of downregulation of gonadotropin-releasing hormone agonist (GnRHa) on Th17/Treg (regulatory T cell) cells in peripheral blood of patients with unexplained repeated implantation failure (RIF).

METHODS

Fifty-two patients who had RIF (≥ 3 consecutive transfers of ≥ 4 high-grade embryos in women under the age of 40 (excluding 40)) of frozen-thawed embryos were studied. Twenty-nine cases receiving simple hormone replacement therapy (HRT) were defined as transfer group, and the remaining 23 cases with HRT combined with GnRHa downregulation were defined as GnRHa downregulation group. In addition, 30 cases of the normal early pregnancy group were selected as control group.

RESULTS

Before HRT, the number of Th17 and Treg cells in CD4+ lymphocytes was increased and decreased, respectively, with the ratio of Th17/Treg cells increased in HRT group compared with the control group (p < 0.05). On the day of progesterone conversion, compared with the HRT group, the percentage of Th17 and Treg cells was decreased and increased, respectively, with the ratio of Th17/Treg cells decreased significantly in GnRHa downregulation group (p < 0.05). The estrogen E2 levels of the GnRHa downregulation group were slightly higher than those of the HRT group, with no significant difference between the two groups (p > 0.05). Further, there was no significant difference in the levels of chorionic gonadotropin at the 14th day and the 21st day after transplantation between HRT group and GnRHa downregulation group (p > 0.05).

CONCLUSION

There were an increase and a decrease in the number of Th17 and Treg cells, respectively, with Th17/Treg cells imbalanced in unexplained RIF. GnRHa downregulation may play a direct immunomodulatory role in disrupting the imbalance and then improve the endometrial receptivity. These effects did not depend on the E2 levels in peripheral blood, nor affect early embryonic development.

Effect of gonadotropin-releasing hormone vaccination on T lymphocyte changes in male rats

The aim of this study was to detect the effect of immunization against gonadotropin-releasing hormone (GnRH) on cell-meditated immunity. Three-week-old male Sprague-Dawley rats (n=32) were randomly and equally assigned to two groups: 1) GnRH-tandem-ovalbumin immunized group; and 2) the control group (injected with an equivalent Al(OH)₃ adjuvant). Blood samples were collected at two-week intervals to assess the level of GnRH-specific antibodies and testosterone. Moreover, blood and thymus samples were also collected to analyze the T lymphocyte subpopulations one and two months after the last booster immunization. T lymphocyte immunity against GnRH was activated during the first month post-immunization as exhibited by increased numbers of CD3+ (P<0.05) and CD4+ (P<0.05)T lymphocytes following testosterone suppression (P<0.01), which was then restored and maintained at appropriate levels in the second month. In contrast, the differentiation of T lymphocytes in the thymus was reduced during the first month after immunization as exhibited by the significant decreased number of CD3+ (P<0.05) cells, followed by the restoration and heightened numbers at later time points for both the number of CD3+ (P<0.05) and CD4+ (P<0.01)T lymphocytes. These results suggest that immunization against GnRH interferes with the number of lymphocytes during the early time points following immunization. The number of T lymphocytes initially decreased in the peripheral blood following immunization, but was replenished by newly exported cells from the thymus which eventually restored the T lymphocytes to normal levels.

Differences in Hypercholesterolemia and Atherogenesis Induced by Common Androgen Deprivation Therapies in Male Mice

BACKGROUND

Treatment of prostate cancer often involves androgen deprivation therapy (ADT) by gonadotropin-releasing hormone (GnRH) receptor agonists, GnRH receptor antagonists, or orchiectomy. ADT may increase the rate of cardiovascular disease events, but recent clinical studies suggested that not all means of ADT carry the same risk, raising the possibility of non-testosterone-mediated effects of different forms of ADT on atherosclerosis. Here we compared effects of ADT on atherosclerosis in intact and orchiectomized Apoe-deficient mice.

METHODS AND RESULTS

Chow-fed Apoe-deficient mice were allocated to orchiectomy and/or monthly injections with the GnRH receptor agonist leuprolide or the GnRH receptor antagonist degarelix. Atherosclerosis was quantified at 26 weeks of age in the aortic arch by en face examination and in the aortic root by histology. In intact Apoe-deficient mice, all types of ADT reduced testosterone production to castration levels. Although hypercholesterolemia was accentuated in leuprolide-treated mice, the amount and composition of atherosclerosis was not different between the different types of ADT. In orchiectomized Apoe-deficient mice, leuprolide, but not degarelix, augmented hypercholesterolemia, changed body, thymus, and spleen weights, and increased atherosclerosis in the aortic root. No direct effects of the drugs were detectable on cytokine secretion from murine bone marrow-derived macrophages or on splenocyte proliferation.

CONCLUSIONS

No differences in the development of atherosclerosis were detected among groups of intact Apoe-deficient mice treated with different types of ADT. A pro-atherogenic, possibly cholesterol-mediated, effect of leuprolide was seen in orchiectomized mice that might be relevant for understanding the potential cardiovascular risk associated with GnRH agonist-based ADT.

Sex hormones and immune dimorphism

The functioning of the immune system of the body is regulated by many factors. The abnormal regulation of the immune system may result in some pathological conditions. Sex hormones of reproductive system are one of the major factors that regulate immune system due to the presence of hormone receptors on immune cells. The interaction of sex hormones and immune cells through the receptors on these cells effect the release of cytokines which determines the proliferation, differentiation, and maturation of different types of immunocytes and as a result the outcome of inflammatory or autoimmune diseases. The different regulations of sex hormones in both sexes result in immune dimorphism. In this review article the mechanism of regulation of immune system in different sexes and its impact are discussed.

Ovarian hormone withdrawal in prepubertal developmental stage does not prevent thymic involution in rats

The study was undertaken to assess the effects of ovarian hormone withdrawal in prepubertal age on thymopoiesis in 2- (young) and 11-month-old (middle-aged) rats. In ovariectomized (Ox) rats, irrespective of age, thymic weight and cellularity were greater than in age-matched controls, but the values of both parameters exhibited the age-related decline. In addition, although thymopoietic efficiency was increased in both groups of Ox rats when compared with age-matched controls, thymopoiesis exhibited the age-related decline mirrored in the lower numbers of both CD4+ and CD8+ recent thymic emigrants in peripheral blood. This reflected the prethymic changes affecting bone marrow progenitor generation/entry and the thymic alterations encompassing the impaired progenitor progression through early pre-T-cell receptor developmental stages (defined by CD45RC/CD2 expression) and, possibly, a more pronounced decrease in the proliferation of the most mature thymocytes. Apart from the changes at thymocyte level, in Ox rats the age-related alterations in thymic stroma (substantiated in a prominent loss of thymic epithelial cells) were registered. Ovariectomy-induced changes in thymic lymphoid and epithelial component, most probably, influenced each other leading to the increase in thymic expression of interleukin-6 and interleukin-7 mRNAs along with time after ovariectomy. Collectively, the study showed that the withdrawal of ovarian hormones in prepubertal age increases the efficiency of thymopoiesis in young adult rats, but does not prevent decline in thymopoiesis occurring with age.

Thymic rejuvenation and aging

The thymus is a vital organ for homeostatic maintenance of the peripheral immune system. It is within this mediastinal tissue that T cells develop and are extensively educated and exported to the periphery for establishment of a functional and effective immune system. A striking paradoxical feature of this critical lymphoid tissue is that it undergoes profound age-associated involution. Thymic decline is of minimal consequence to healthy individuals, but the reduced efficacy of the immune system with age has direct etiological linkages with an increase in diseases including opportunistic infections, autoimmunity, and incidence/burden of cancer. Furthermore the inability of adults to restore immune function following insult induced by chemotherapy, ionizing radiation exposure or therapy, and infections (e.g. HIV-1) leads to increased morbidity and often mortality in the elderly. For these reasons, it is important that investigators strive to translate their understanding of mechanisms that drive thymic involution, and develop safe and effective strategies to rejuvenate the thymus in settings of clinical need. In this review, we present a discussion of the current status of thymic rejuvenation efforts associated with: sex steroid ablation, cytokines, growth factors, and hormones.

Role of ovarian hormones in T-cell homeostasis: from the thymus to the periphery

The study explored the putative role of ovarian hormones in the peripubertal remodelling of peripheral T-cell compartment. Ovariectomy at age of 1 month enhanced the peripubertal rise in CD4+ and CD8+ cell numbers in peripheral blood (PB) and spleen from 2-month-old rats. This reflected maintenance of thymopoietic efficiency at the prepubertal level (judging by numbers of the most mature CD4+ and CD8+ thymocytes and recent thymic emigrants) and alterations in T-cell survival/proliferation in the periphery. Compared with age-matched controls, the frequency of apoptotic cells among CD8+ peripheral blood lymphocytes (PBLs) and CD4+ and CD8+ splenocytes was diminished in ovariectomized (Ox) rats, at least partly, due to lower CD95 surface density. The diminished frequency of the apoptotic T splenocytes could also be associated with the rise in the amount of splenic IL-7 mRNA. Additionally, the latter finding was consistent with the augmented proliferation of CD4+ and CD8+ splenocytes. However, the enhanced proliferation of these cells could also be linked to the rise in IL-2 receptor surface density. This increase was related to the enhanced splenic TNF-α mRNA expression. Additionally, ovariectomy led to the phenotypic alterations in the major PBL and splenic T-cell subsets by diminishing/preventing the peripubertal changes in the frequency of cells at distinct stages of post-thymic differentiation/maturation (recent thymic emigrants, mature naïve and memory cells), and by decreasing the frequency of NKT cells within peripheral CD8+ subsets. In addition to numerical and phenotypic changes in T-cell compartment (due to the lack of ovarian hormone action at both the thymic and peripheral level), Ox rats exhibited a much larger delayed-type hypersensitivity (DTH) response compared with age-matched controls. This suggested the augmented T-cell-mediated immune response in Ox rats compared with aged-matched controls.

Luteinizing hormone receptor deficiency increases the susceptibility to alkylating agent-induced lymphomagenesis in mice

Previous studies have revealed a close link between luteinizing hormone (LH)/human chorionic gonadotropin (hCG) signaling and oncogenesis in gonadal and nongonadal tissues. To investigate whether genetic ablation of LH receptor (Lhr) affects the animal's oncogenic susceptibility, adult female wild-type (wt), heterozygous, and homozygous Lhr knockout (LhrKO) mice were intraperitoneally injected with an alkylating agent, N-methyl-N-nitrosourea (MNU, 50 mg/kg of body weight). The mice were sacrificed when they were short of breath or 10 months after the injection. The results showed that MNU induced non-Hodgkin's thymic and lymphonodus lymphomas in 70.6% and 100% of heterozygous and homozygous animals, respectively, compared with 35.7% in wt siblings. The tumor development was rapid; they were more aggressive and metastasized to the spleen, liver, and kidney in Lhr-deficient mice compared to wt siblings. All tumors were immunostained-positive for a T-cell specific marker, CD3, but not for a B-cell marker, CD22, suggesting that all the lymphomas arose from T-cells, which are known to be LH/hCG receptor-positive. There was no rearrangement of the Lhr gene locus or differences in thymic cell proliferation among the genotypes. However, apoptosis was lower in the Lhr-deficient thymuses. The thymic Bcl-2 levels were elevated and caspase-3 activation was reduced in Lhr heterozygous and homozygous animals. In conclusion, MNU induced a higher incidence and an earlier onset of aggressive lymphomas in LhrKO animals, which may be associated with a reduction in apoptosis of thymocytes.

Luteinizing hormone-releasing hormone enhances T cell recovery following allogeneic bone marrow transplantation

Posttransplant immunodeficiency, specifically a lack of T cell reconstitution, is a major complication of allogeneic bone marrow transplantation. This immunosuppression results in an increase in morbidity and mortality from infections and very likely contributes to relapse. In this study, we demonstrate that sex steroid ablation using leuprolide acetate, a luteinizing hormone-releasing hormone agonist (LHRHa), increases the number of lymphoid and myeloid progenitor cells in the bone marrow and developing thymocytes in the thymus. Although few differences are observed in the peripheral myeloid compartments, the enhanced thymic reconstitution following LHRHa treatment and allogeneic bone marrow transplantation leads to enhanced peripheral T cell recovery, predominantly in the naive T cell compartment. This results in an increase in T cell function in vivo and in vitro. Graft-versus-host-disease is not exacerbated by LHRHa treatment and graft-versus-tumor activity is maintained. Because LHRHa allows for reversible (and temporary) sex steroid ablation, has a strong safety profile, and has been clinically approved for diseases such as prostate and breast cancer, this drug treatment represents a novel therapeutic approach to reversal of thymic atrophy and enhancement of immunity following immunosuppression.

Clinical strategies to enhance T cell reconstitution

Strategies to enhance T cell recovery are of increasing clinical importance to overcome long lasting T cell deficiencies, which occur in association with infections, autoimmunity and chemo/radiotherapy as well as aging of the immune system. In this review we discuss those strategies that are close to or in the clinic. Interleukin-7, sex steroid modulation, keratinocyte growth factor, growth hormone and cellular therapies using ex vivo generated T-cell precursors are currently being tested in recipients of a hematopoietic stem cell transplantation and patients with malignancies or HIV/AIDS.

Drug-induced reversible lymphoid dyscrasia: a clonal lymphomatoid dermatitis of memory and activated T cells

Certain systemic conditions predispose patients to excessive lymphocyte responses to immune-perturbing drugs, which may progress to malignant lymphoma. Many pathologists and clinicians believe that differentiation of pseudolymphoma from cutaneous T cell lymphoma (CTCL) can be reliably made through phenotypic and molecular analysis. We encountered 15 cases of atypical cutaneous T-cell lymphoid hyperplasia in the setting of drug therapy. We explored phenotypic anomalies using antibodies to CD2, 3, 4, 7, 8, 20, 30 and CD62 K and sought T-cell receptor gene rearrangements by a polymerase chain reaction methodology. The lymphoid infiltrates showed reproducible CD7 and/or CD62 K deletion in concert with T cell clonality and variable CD30 positivity-findings similar to those of CTCL-but the rashes resolved or improved substantially after drug modulation. We hypothesize that the infiltrates represent an unrepressed expansion of CD7- and CD62 K-negative activated memory T lymphocytes in response to antigenic triggers. We propose the term "drug-induced reversible lymphoid dyscrasia" to describe this entity.

Hormone therapy in men and risk of cardiac allograft rejection

Hormone therapy with leuprolide acetate (Lupron) is frequently used to treat prostate cancer, a common malignancy expected to be diagnosed in >180,000 men in the United States this year. In addition, testosterone supplementation is frequently recommended for adult men with reduced libido or impotence and decreased serum levels of testosterone. Although these hormone therapies are generally considered benign, we describe 3 cases of acute cardiac rejection temporally associated with the use of these drugs in men who have undergone cardiac transplantation. To our knowledge, this is the first such description of this phenomenon in the literature.

Effect of gonadotropin-releasing hormone agonists on monocyte chemotactic protein-1 production and macrophage infiltration in leiomyomatous uterus

OBJECTIVE

The level of monocyte chemotactic protein-1 (MCP-1), a potent chemoattractant for monocytes, is fivefold higher in myometrium than in leiomyoma. We have previously shown that myometrium from women using GnRH agonists (GnRH-a) express the highest levels of MCP-1, which has antiproliferative effects on leiomyoma cells. We hypothesized that MCP-1 may have a direct paracrine effect in leiomyomatous uterus rather than acting by way of chemoattraction of macrophages.

DESIGN

Cross-sectional study.

SETTING

University medical center.

PATIENT(S)

Women with leiomyoma (n = 32).

INTERVENTION(S)

Immunohistochemical analysis performed in the myometrium and leiomyoma of women receiving (n = 11) and not receiving (n = 21) GnRH-a treatment.

MAIN OUTCOME MEASURE(S)

The MCP-1 levels and macrophage counts determined by immunohistochemistry in the myometrium and leiomyoma of women receiving GnRH-a were compared to the levels and counts in women not receiving GnRH-a.

RESULT(S)

Samples from all 11 patients using GnRH-a revealed strong MCP-1 staining, whereas staining was only weakly present in 11 and absent in 10 samples from patients not receiving GnRH-a, revealing a significant difference in MCP-1 expression between GnRH-a users versus nonusers (P=.006). The number of tissue macrophages between GnRH-a users and nonusers was not significantly different.

CONCLUSION(S)

We found that there is an increase in the MCP-1 protein expression in the myometrium of women receiving GnRH-a treatment. On the other hand, we have not observed a difference in the macrophage count and distribution with GnRH-a treatment, suggesting a potentially direct antiproliferative role for MCP-1 rather than acting by means of chemoattraction of macrophages.

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.

Changes in lymphoid tissue after treatment with a gonadotropin releasing hormone antagonist in the neonatal marmoset (Callithrix jacchus)

PROBLEM

The effect of neonatal treatment with a gonadotropin releasing hormone (GnRH) antagonist on the morphology and distribution of lymphocytes in lymphoid tissue of the infant marmoset was examined.

METHOD OF STUDY

From a screened panel of antihuman antibodies for specific immune cells, antibodies for the CD20 and CD3 antigens showed excellent reactivity with marmoset tissue. Five sets of marmoset twins were treated with either the GnRH antagonist or a vehicle from birth, and were euthanized at 7 to 9 (3 sets) or 16 to 20 weeks (2 sets) of age. The spleen, thymus, and inguinal lymph nodes from each animal were processed for immunocytochemistry, and the number of cells expressing the CD20 and CD3 antigens were quantified.

RESULTS

Control twins exhibited high plasma levels of testosterone, characteristic of the neonatal period, whereas testosterone concentrations were reduced (P = 0.001) to detection limits in the GnRH antagonist-treated twins. Microscopic evaluation suggested that treatment reduced the volume and cellularity of the thymic cortex, resulting in a decrease in the cortical-to-medullary ratio. Treatment reduced (P = 0.046) the number of thymocytes expressing the B-cell antigen (CD20) and marginally lowered (P = 0.067) the number expressing the T-cell antigen (CD3) in the thymic medulla. In the spleens of treated animals, periarterial lymphatic sheaths were less prominent on microscopic examination, and there were marginally fewer (P = 0.064) CD3+ cells. Numbers of CD20+ lymphocytes in the peripheral white pulp of the spleen and in the germinal centers of the lymph nodes, or CD3+ cells in the paracortex and germinal centers of the lymph nodes, were not altered by treatment.

CONCLUSION

Neonatal treatment with a GnRH antagonist may alter maturational processes for B and T cells in the thymus and spleen of the marmoset and may deprive the immune system of its normal sensitivity to GnRH at a potentially critical time in development.