Sex hormones influence on the immune system: basic and clinical aspects in autoimmunity

Sex hormones seem to play an important role as modulators of the autoimmune disease onset/perpetuation. Generally, steroid hormones are implicated in the immune response, with estrogens as enhancers at least of the humoral immunity and androgens and progesterone (and glucocorticoids) as natural immunosuppressors. Synovial fluid levels (SF) of proinflammatory estrogens relative to androgens are significantly elevated in both male and female rheumatoid arthritis (RA) patients, as compared to controls, which is most probably due to increase of local enzymatic aromatase activity. Serum levels of estrogens have been found altered in RA patients, particularly estradiol in man. Thus, available steroid prehormones are rapidly converted to proinflammatory estrogens in the synovial tissue in the presence of inflammatory cytokines (i.e., TNFa, IL-1, IL-6). The increased estrogen concentrations observed in RA SF of both sexes are characterized mainly by the hydroxylated forms, in particular, 16a-hydroxyestrone, showing a mitogenic tumor growth stimulating role. Altered serum hydroxylated estrogens have been found also in serum of systemic lupus erythematosus (SLE) patients. As a matter of fact, our recent studies indicate that 17-b estradiol (E2) clearly enhanced the expression of markers of cell growth and proliferation, whereas testosterone (T) induced an increase of markers indicating DNA damage and apoptosis. In particular, our data further shows that the enhancing role of estrogens on immune/inflammatory response is exerted by activating the NFkB complex pathway. In conclusion, locally increased estrogens (i.e., synovial tissue in RA or skin in SLE) might exert activating effects on cell proliferation, including macrophages and fibroblasts, suggesting new roles for estrogens in autoimmunity.

Characterization of the intra-prostatic immune cell infiltration in androgen-deprived prostate cancer patients

INTRODUCTION

Our goal was to study the hormonal regulation of immune cell infiltration in prostate cancer patients treated by androgen deprivation therapy (ADT) using an optimized computer-assistance quantification approach.

METHODS

The relative density of immune cell subtypes (CD3(+), CD8(+), CD20(+), CD56(+), CD68(+) and Foxp3(+)) was analyzed by immunohistochemistry in archived prostate specimens from control patients (radical prostatectomy only, n=40) and ADT-treated patients (ADT prior to radical prostatectomy, n=35) using an image analysis software and a whole-slide scanner.

RESULTS

ADT-treated patients had significantly increased relative density of CD3(+) (p<0.001) and CD8(+) T lymphocytes (p<0.001) as well as CD68(+) macrophages (p<0.001). Elevated abundance of CD56(+) Natural Killer (NK) cells was associated with a lower risk of prostate cancer progression (p=0.044), while a high density of CD68(+) macrophages was related to an increased risk of biochemical recurrence (p=0.011).

CONCLUSIONS

Our results demonstrate that the infiltration of specific immune cell subtypes is modulated by ADT. Furthermore our data confirm that NK cells have a protective role against tumor progression while macrophages seem to favor the development of advanced prostate cancer.

Effect of androgens on the development of mouse follicles growing in vitro

The effects of androgens on ovarian follicular development have been investigated using a whole follicle culture system. Follicles obtained from mouse ovaries and cultured in the presence of anti-androgen serum grew more slowly than control follicles. This effect was reversed by the addition of androstenedione to the medium. A similar effect was obtained when receptor-mediated effects of androgens were blocked using an androgen receptor antagonist. When follicles were grown in concentrations of FSH that are marginal for follicle development, they developed faster in the presence of a non-aromatizable androgen, dihydroxytestosterone. The results indicate that androgens exert a direct, stimulatory role on the growth and development of mouse antral follicles, in vitro.

Mechanism of immunosuppression in males following trauma-hemorrhage. Critical role of testosterone

OBJECTIVE

To determine whether male sex steroids contribute to the depression in cell-mediated immunity following trauma-hemorrhage and resuscitation.

DESIGN

Two weeks before the induction of soft-tissue trauma (2.5-cm midline laparotomy) and hemorrhagic shock (mean [+/-SEM] blood pressure, 35 +/- 5 mm Hg), male C3H/HeN mice were castrated or sham castrated. Following trauma-hemorrhage, the mice were resuscitated and killed 24 hours thereafter to obtain whole blood and the spleen.

RESULTS

Splenocyte proliferation and splenocyte interleukin-2 and interleukin-3 release were significantly depressed in sham-castrated animals after trauma-hemorrhage. In contrast, these variables in castrated mice after trauma-hemorrhage were similar to those in sham-operated animals. Corticosterone plasma levels were significantly elevated in both trauma-hemorrhage groups compared with those in sham-operated mice. Plasma testosterone levels were undetectable in castrated animals and detectable in sham-castrated mice.

CONCLUSIONS

Castration before soft-tissue trauma and hemorrhagic shock maintains normal immune function in male mice, but sham-castrated male mice show significant immunodepression. The maintenance of immune function by androgen deficiency does not seem to be related to changes in the release of corticosterone. We conclude that male sex steroids are involved in the immunodepression observed after trauma-hemorrhage. Thus, the use of testosterone-blocking agents following trauma-hemorrhage should prevent the depression of immune functions and decrease the susceptibility to sepsis under those conditions.

The influence of season, photoperiod, and pineal melatonin on immune function

In addition to the well-documented seasonal cycles of mating and birth, there are also significant seasonal cycles of illness and death among many animal populations. Challenging winter conditions (i.e., low ambient temperature and decreased food availability) can directly induce death via hypothermia, starvation, or shock. Coping with these challenges can also indirectly increase morbidity and mortality by increasing glucocorticoid secretion, which can compromise immune function. Many environmental challenges are recurrent and thus predictable; animals could enhance survival, and presumably increase fitness, if they could anticipate immunologically challenging conditions in order to cope with these seasonal threats to health. The annual cycle of changing photoperiod provides an accurate indicator of time of year and thus allows immunological adjustments prior to the deterioration of conditions. Pineal melatonin codes day length information. Short day lengths enhance several aspects of immune function in laboratory studies, and melatonin appears to mediate many of the enhanced immunological effects of photoperiod. Generally, field studies report compromised immune function during the short days of autumn and winter. The conflict between laboratory and field data is addressed with a multifactor approach. The evidence for seasonal fluctuations in lymphatic tissue size and structure, as well as immune function and disease processes, is reviewed. The role of pineal melatonin and the hormones regulated by melatonin is discussed from an evolutionary and adaptive functional perspective. Finally, the clinically significance of seasonal fluctuations in immune function is presented. Taken together, it appears that seasonal fluctuations in immune parameters, mediated by melatonin, could have profound effects on the etiology and progression of diseases in humans and nonhuman animals. An adaptive functional perspective is critical to gain insights into the interaction among melatonin, immune function, and disease processes.

Androgens alter B cell development in normal male mice

Castration of normal male mice leads to splenic enlargement and expansion of the B cell population. Since the spleen does not express receptors for androgens, these changes are most likely mediated by effects of androgens on other target organs. Two potential sites of androgen-mediated effects on B cells are evaluated in these studies: thymus and bone marrow. We first confirmed other findings indicating that castration of normal male mice results in expansion in the numbers of bone marrow B cells and then extended these observations by showing that these changes were reversible following androgen replacement. B cell expansion in castrate marrow and spleen was not altered by prior thymectomy, suggesting that thymic androgen receptors are not involved in the observed effects. Androgen receptors were found to be present in both immature B cells and marrow stromal cells by immunoblotting and ligand binding assays. The results suggest a direct modulatory role for androgens on B cells within the bone marrow compartment.

Hormonal regulation of immune responses

Females have stronger immune responses than males. Female predominance in autoimmune diseases in both experimental animals and in man is also established. Sex hormones and some other steroid hormones have been shown to exert immunoregulatory effects in both in vivo and in vitro situations. Important mechanisms of hormone action on lymphocytes have gradually been revealed. In this paper the most intriguing effects of steroid hormones on immune system and present data suggesting hormonal influence on the pathogenesis of autoimmune diseases are summarized.

Androgen ablation augments prostate cancer vaccine immunogenicity only when applied after immunization

BACKGROUND

Androgen ablation (AA) causes apoptosis of normal and neoplastic prostate cells. It is a standard treatment for advanced prostate cancer. Androgen ablation-mediated immunological effects include bone marrow hyperplasia, thymic regeneration, T and B cell lymphopoeisis and restoration of age-related peripheral T cell dysfunction. Androgens also regulate the transcription of several cytokines. Dendritic cells (DC) are the most potent antigen presenting cells that can activate antigen-specific naïve T cells. Despite myriad clinical trials involving DC-based prostate cancer immunotherapies, the effects of AA on DC function remain largely uncharacterized. Therefore, we investigated the effects of AA on DC and whether it could improve the efficacy of prostate cancer immunotherapy.

METHODS

Cytokine expression changes due to AA were quantified by multiplex ELISA. Flow cytometry was used to assess AA-mediated effects on DC maturation and expression of costimulatory markers. Mixed leukocyte reactions and cell-mediated lysis assays elucidated the role of androgens in DC function. The effect of AA on the efficacy of vaccination against a prostate tumor-associated antigen was tested using Elispot assays.

RESULTS

Androgen ablation increased dendritic cell maturation and costimulatory marker expression, but had no effect on DC costimulatory function. However, DC isolated from castrated mice increased the expression of key cytokines by antigen-experienced T cells while decreasing their expression in naïve cells. Finally, androgen ablation improved immune responses to vaccination only when applied after immunization.

CONCLUSION

Androgen ablation causes differential effects of DC on primary and secondary T cell responses, thus augmenting vaccine immunogenicity only when applied after immunization.

Gender and sex hormones influence the response to trauma and sepsis: potential therapeutic approaches

Several clinical and experimental studies have demonstrated gender dimorphism in immune and organ responsiveness and in the susceptibility to and morbidity from shock, trauma, and sepsis. In this respect, cell-mediated immune responses have been shown to be depressed in males following trauma-hemorrhage, whereas they were aintained/enhanced in proestrus females. Furthermore, sex hormones have been shown to be responsible for this gender-specific immune response following adverse circulatory conditions. More specifically, studies indicate that androgens produce immunodepression following trauma-hemorrhage in males. In contrast, female sex steroids appear to exhibit immunoprotective properties following trauma and severe blood loss. With regard to the underlying mechanisms, receptors for sex hormones have been identified on various immune cells suggesting direct effects of these hormones on the immune cells. Alternatively, indirect effects of sex hormones, ie, modulation of cardiovascular responses or androgen- and estrogen-synthesizing enzymes, might contribute to gender-specific immune responses. Recent studies indicate that sex hormones, eg, dehydroepiandrosterone (DHEA), also modulate the function of peripheral blood mononuclear cells in surgical patients. Thus, the immunomodulatory properties of sex hormones/receptor antagonists/sex steroid synthesizing enzymes following trauma-hemorrhage suggests novel therapeutic strategies for the treatment of immunodepression in surgical patients.

Alterations in peripheral B cells and B cell progenitors following androgen ablation in mice

The production of B lymphocytes is regulated in part by physiologic levels of androgens and estrogens. While these sex hormones down-regulate B lymphopoiesis, augmentation of B lymphopoiesis occurs under conditions where androgen or estrogen levels are decreased. In this study we examine the effect of androgen ablation of male mice on B lymphopoiesis and on the phenotypic composition of peripheral B lymphocyte populations. Spleen and thymic weights are significantly increased following castration, as is the total number of peripheral blood lymphocytes. However, the absolute numbers of B cells in the periphery are selectively increased following castration; the numbers of T cells, NK cells and granulocytes remain unchanged. The increase in circulating B cells is due largely to increases in the numbers of recent bone marrow emigrants expressing a B220(lo+)CD24(hi+) phenotype and these cells remain significantly elevated in castrated mice for up to 54 days post-castration. Similar increases in the percentages of newly emigrated B cells are observed in mice that lack a functional androgen receptor (TFM:). Finally, assessments of B cell progenitors in the bone marrow revealed significant increases in the relative numbers of IL-7-responsive B cell progenitors, including cells in Hardy fractions B (early pro-B cells), C (late pro-B cells), D (pre-B cells) and E (immature B cells). These findings demonstrate that androgen ablation following castration significantly and selectively alters the composition of peripheral B cells in mice. Further, these alterations result from the potentiating effects of androgen ablation on IL-7-responsive pro-B cell progenitors.

The proliferative effect of "anti-androgens" on the androgen-sensitive human prostate tumor cell line LNCaP

The effect of steroidal and nonsteroidal "anti-androgens" on the proliferative capacity of androgen-sensitive LNCaP-FGC human prostate tumor cells in culture was studied using charcoal-dextran stripped human serum-supplemented media. Cyproterone and medroxyprogesterone acetates, flutamide, hydroxyflutamide, and anandron (R23908) were administered alone at concentrations between 3 X 10(-12) and 3 X 10(-6) M. Results indicated that although medroxyprogesterone induced maximal proliferation at 3 X 10(-9) M, the other "anti-androgens" (with the exception of flutamide that was ineffective) were effective at 3 X 10(-8) M and higher concentrations; the amplitude of the proliferative response by these compounds was comparable to that elicited by estradiol-17 beta (3 to 5-fold over control). None of the anti-androgens tested triggered the shutoff effect characteristic of androgen action. When 3 X 10(-10) M DHT and the above mentioned anti-androgens were administered simultaneously, a synergistic pattern was seen; on the contrary, 3 X 10(-8) M DHT cancelled the proliferative effect of each of the anti-androgens when administered simultaneously. The relative binding affinity of these anti-androgens to androgen receptors present in LNCaP-FGC cells did not correlate well with their proliferative efficiency. The data collected were interpreted within the premises of the negative control hypotheses for the regulation of cell proliferation in metazoans. Within those premises, results became compatible with the notion that first, "anti-androgens" elicited the proliferation of androgen-sensitive cells by neutralizing the effect of a serum-borne inhibitor (androcolyone-I); this event seems not to be mediated by androgens receptors. Second, anti-androgens did not trigger a proliferative shutoff response like androgens do, i.e. the proliferative pattern induced by anti-androgens was comparable to that elicited by estrogens and progestins. Third, when administered simultaneously with 3 X 10(-10) M DHT, anti-androgens behaved synergistically. Fourth, the DHT-induced shutoff effect consistently overrode the proliferative effect generated by anti-androgens and estrogens when added alone. Finally, taken together these results raise important questions regarding the therapeutic role of anti-androgens in prostate cancer.

Sex hormones and rheumatoid arthritis

Sex hormones are implicated in the immune response, with estrogens as enhancers at least of the humoral immunity and androgens and progesterone as natural immune-suppressors. In male rheumatoid arthritis (RA) patients, androgen replacement seems to ameliorate the disease and supports their involvement in the pathophysiology of the disease. The combination of androgens with cyclosporin A or methotrexate has been found to potentiate the apoptosis of monocytic inflammatory cells as well as to reduce the cell growth at least in vitro. Considerable interest has been devoted in the last years as to whether the use of oral contraceptive pills (OCs) may have a protective effect on the risk of RA. The results of many controlled studies have been found contradictory. At the present time, no consensus has been achieved regarding OCs administration and its relationship to the prevention or development of RA. In addition, an association of estrogen receptor gene polymorphism with age at onset of RA has been observed and might further explain inter-individual clinical and therapeutical-response variations. Local increased estrogen concentrations and decreased androgen levels have been observed in RA synovial fluids and seem to play a more important role in the immune/inflammatory local response.

Male gonadal environment paradoxically promotes dacryoadenitis in nonobese diabetic mice

Similar to pancreatic islets, submandibular glands are more rapidly infiltrated in female NOD mice than in males. The present comparative analysis of cellular infiltrations in lacrimal glands, however, revealed the opposite finding. At 12 wk of age, approximately 25% of male lacrimal tissue area is infiltrated, whereas age-matched female NOD mice still lack major signs of inflammation. T cells predominate in early stages of invasion, but B cells accumulate promptly in more advanced stages, and ultimately dominate over T cells. Dacryoadenitis is promoted by sex hormones, as suggested by the reduced infiltrations seen in orchidectomized NOD males (P < 0.01). It is also controlled by the local environment provided by the lacrimal tissue. Splenocytes from 4- and 20-wk-old female NOD mice cause massive lesions upon adoptive transfer into NOD male recipients while, conversely, female recipients develop barely any histological sign of infiltration, even after transfer of splenocytes from 20-wk-old donor males. These observations provide strong evidence for a dacryoadenitis-promoting role of male gonadal hormones in NOD mice, a finding that contrasts the known androgen-mediated protective effects on insulitis and submandibulitis in the same strain and on dacryoadenitis in other animal models of Sjögren's syndrome.

Response to acute hCG stimulation and steroidogenic potential of Leydig cell fibroblastic precursors in humans

The process of early testosterone (T) secretion and Leydig cell differentiation in humans was studied to explore the steroidogenic capacity of Leydig cell fibroblastic precursors. Seven cryptorchid boys received hCG prior to orchidopexy. Patients CP, PB, and MR received one injection of 1000 IU; patients JR and GG, three daily injections of 1000 IU, and patients MP and MM, five daily injections of 1000 IU. A testicular biopsy was obtained at the time of operation, 24 hours after the last injection. Serum T (ng/dl) before and after hCG stimulation and testicular T (ng/g) were determined by RIA. A control prepubertal testis (tumoral orchidectomy) was incubated in vitro and showed a time-dependent accumulation of T both in the medium and the testicular tissue. Testosterone released into the medium at 1, 2, and 4 hours was 0.76, 1.43, and 4.03 ng/ml, respectively. Tissue T at 0, 1, 2, and 4 hours was 9, 11, 16, and 24 ng/g, respectively. This indicates synthesis and secretion of T into the medium. Control testes showed abundant fibroblastic precursors with scanty cytoplasm, few organelles, heterochromatic nuclei, and minute nucleoli. No Leydig cells were present. After 1 day of hCG stimulation, numerous fibroblasts were activated, displaying enlarged cytoplasms with increased numbers of organelles, nuclei rich in euchromatin, and bigger nucleoli. No Leydig cells were present. Basal serum testosterone was 58.2 +/- 45.3 ng/dl and 87.3 +/- 42.0 after hCG administration, while testicular T was 974.0 +/- 686.0 ng/g (control prepubertal testicular T is 10-50 ng/g). After 3 days of hCG, activated fibroblasts increased and immature Leydig cells appeared. Basal serum T was 35.5 +/- 7.8 ng/dl and 394.0 +/- 24.0 after hCG stimulation, while testicular T rose to 2797.5 +/- 1222.6 ng/g. After 5 days, mature Leydig cells appeared for the first time. Serum T was 58 +/- 59.3 ng/dl (basal) and 641.5 +/- 390 ng/dl (after hCG); testicular T was 789 ng/g (patient MM did not have a value for testicular T). HCG induced numerous coated pits and endocytic vesicles in activated fibroblasts and young Leydig cells, suggesting receptor aggregation and internalization of hormone-receptor complexes. Peroxidase-antiperoxidase (PAP) localization of T was positive in peritubular fibroblasts and Leydig cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Influence of physiological androgen levels on wound healing and immune status in men

Aging in men is associated with a progressive decline in the production of several hormones, including androgens. The extent to which an age-dependent decline in androgen levels lead to health problems or can affect quality of life remains under debate. Clinical results on replacement therapy do not yet provide a definitive clue on the benefit/risk balance. A sexual dimorphism of the immune system is well established, and the differences between female and male immune responses under normal, as well as pathological, conditions are generally attributed to the influence of estrogens, progestins, and androgens. The suppressive effects of male sex hormones on immune functions have been observed in a wide variety of disease processes and appear to be testosterone-mediated. Endogenous testosterone inhibits skin wound healing response in males and is associated with an enhanced inflammatory response. Although there are no known gender-related differences in permeability barrier function in adults, estrogens accelerates--whereas testosterone retards--barrier development in fetal skin, and male fetuses demonstrate slower barrier development than female littermates.

The evolving role of immune cells in prostate cancer

Prostate cancer is the most commonly diagnosed cancer and the second leading cause of cancer-related death among men in western countries. Androgen deprivation therapy (ADT) is considered the standard therapy for recurrent prostate cancer; however, this therapy may lead to ADT resistance and tumor progression, which seems to be regulated by epithelial-mesenchymal transition (EMT) and/or neuroendocrine differentiation (NED). In addition, recent data suggested the involvement of either adaptive or innate infiltrated immune cells in the initiation, progression, metastasis, and treatment of prostate cancer. In this review, we outlined the characteristics and roles of these immune cells in the initiation, progression, metastasis, and treatments of prostate cancer. We also summarized the current therapeutic strategies in targeting immune cells of the prostate tumor microenvironment.

Gender dimorphism in immune responses following trauma and hemorrhage

Previous studies have shown marked immunosuppression in males after trauma and hemorrhage. By contrast, immunosuppression was not evident in proestrous female animals. Further support for these findings came from studies demonstrating the immunosuppressive effects of male sex hormones and immunoenhancing effects of female sex hormones. In this regard, administration of 17beta-estradiol or prolactin to male animals after trauma and hemorrhage significantly improved immune function. Furthermore, castration or androgen receptor blockade with flutamide after trauma and hemorrhage in male mice showed similar beneficial effects. Thus, regulation of sex hormone synthesis or their receptor activity appears to be a useful therapeutic approach for patients to cope with the deleterious sequelae of severe trauma and hemorrhage.

The intersection of stress, sex and immunity in fishes

While sexual dimorphism in immune responses has been documented in other vertebrates, evidence for a similar phenomenon in fish is lacking. Here, we review the relationship between immunity, stress, spawning, and sex hormones in fish to gain a better understanding of sex-based differences in fish immune responses and its consequences for aquaculture. It is well known that there is a strong link between the stress response and immune function in fish. In addition, research to date has demonstrated that sexual dimorphism in the stress response exists in many species; yet, the relationship between the sexual dimorphic stress responses and immune function has rarely been explored together. Aside from stress, spawning is also known to trigger changes in fish immune responses. Estrogens and androgens have been shown to modulate the immune system which could account for differences between the two sexes of fish when spawning; however, evidence regarding the sexual dimorphism of these changes varies between fishes and is likely related to the spawning strategy employed by a given species. Sex hormones are also used in aquaculture practices to produce monosex populations, and exposure to these hormones early in development has been shown to impact the development of immune organs in several fishes. While female fish are generally thought to be more robust than males, aquaculture practices should also consider the role that maternal stress has on the immune function of the offspring and what role this plays in compromising the immune response of farmed fish.

Immunomodulatory actions of gonadal steroids may be mediated by gonadotropin-releasing hormone

Estrogens are considered to be immunostimulatory, whereas androgens are considered to be immunosuppressive. We hypothesized that the divergent actions of gonadal steroids on the immune system may be mediated indirectly, via their potent divergent feedback effects on the hypothalamic hormone GnRH, which is itself immunostimulatory. We used the GnRH-deficient HPG/Bm mouse in an effort to disentangle the effects of gonadal steroids from the effects of GnRH. We randomized GnRH-deficient mice and their GnRH-sufficient littermates to receive androgens, estrogens, or GnRH. We subsequently measured B and T cell proliferative responses to mitogen and serum IgG levels. We demonstrate that estrogens exert stimulatory effects on B cell proliferation and serum IgG levels in the presence of GnRH but not in the absence of GnRH. Testosterone exerts suppressive effects on B cell function in the presence of GnRH but not in its absence. Androgens and estrogens exerted divergent actions on T cell function irrespective of the presence and absence of GnRH, although responses were markedly attenuated in GnRH-deficient mice. Our data suggest that the immunostimulatory effects of estrogen and the immunosuppressive effects of androgens on B cell function may be mediated indirectly via GnRH.

Transcriptional and posttranscriptional regulation of human androgen receptor expression by androgen

Autoregulation is a control mechanism common to several proteins of the steroid/thyroid hormone receptor superfamily. In this work, the effect of androgens and antiandrogens on the expression of the human androgen receptor (hAR) in prostate and breast cancer cell lines was studied. Northern blot analysis revealed a decrease in hAR steady state RNA levels in LNCaP cells by 3.3 nM of the synthetic androgen mibolerone. Maximal down-regulation of hAR RNA to 30% of control levels occurred 48 h after hormone addition. T47D breast cancer cells showed a similar effect with mibolerone, while hAR expression in normal skin fibroblasts did not respond to androgen treatment. As shown by nuclease S1 analysis, hAR transcripts initiate at three principal start sites, all of which are equally sensitive to androgen. Steroidal as well as nonsteroidal antiandrogens were capable of partially antagonizing androgen-mediated hAR RNA down-regulation in LNCaP and T47D cells, while not exerting a significant effect when administered alone. While hAR RNA stability was increased by hormone, nuclear run-on analysis revealed a 4-fold reduction of hAR gene transcription 96 h after androgen treatment. Although decreased hAR RNA levels did not coincide with a parallel decrease in AR protein levels, analysis of androgen-inducible reporter constructs demonstrated that prolonged androgen administration to cells results in a progressively impaired sensitivity of the intracellular androgen response mechanism. These results show that prolonged androgen exposure leads, besides its effect on hAR RNA levels, to functional inactivation of the AR. Thus, in vivo, posttranslational control of AR activity appears to be a novel mechanism of negative autoregulation of androgen effects on gene expression.

Sexual Dimorphism of Coronavirus 19 Morbidity and Lethality

The recent coronavirus disease 2019 (COVID-19) pandemic showed a different severity in the disease between males and females. Men have been becoming severely ill at a higher rate than women. These data along with an age-dependent disease susceptibility and mortality in the elderly suggest that sex hormones are the main factors in determining the clinical course of the infection. The differences in aging males versus females and the role of sex hormones in key phenotypes of COVID-19 infection are described in this review. Recommendations based on a dimorphic approach for males and females suggest a sex-specific management the disease.

Gender dimorphism in the myeloid differentiation of bone marrow precursor cells in a murine host bearing a T cell lymphoma

Little information is available regarding the existence of gender dimorphism of tumor growth for most types of tumors. In a previous report we have demonstrated the existence of gender dimorphism in the growth of a murine T cell lymphoma, designated as Dalton's lymphoma (DL); moreover, tumor-associated macrophages (TAM) were found to play a central role in the manifestation of gender dimorphism observed in the growth of this T cell lymphoma. In view of these observations, the present investigation was undertaken to study if gender dimorphism in the growth of a T cell tumor also could be associated with a gender-dependent differential myelopoiesis of bone marrow cells. We have demonstrated the existence of a gender dimorphism in the proliferation, apoptosis and myeloid differentiation of bone marrow cells obtained from male and female tumor-bearing hosts. Androgen and estrogen were found to alter directly the growth properties of bone marrow cells, as also determined by the use of receptor antagonists of these hormones, flutamide and tamoxifen. Bone marrow cells of male and female tumor-bearing hosts also showed a differential expression of the cell cycle and apoptosis regulatory protein p53 and macrophage-colony stimulating factor (M-CSF) genes. Bone marrow cells of male tumor-bearing hosts showed a predominant differentiation in the macrophage lineage whereas those of female tumor-bearing mice were in the granulocyte lineage. Bone marrow-derived macrophages (BMDM) from male and female tumor-bearing mice also showed the existence of gender dimorphism with respect to their differentiation and activation. These observations are of clinical significance with respect to understanding of the host-tumor relationship at the level of gender dimorphism of myelopoiesis.