Glucocorticoid-independent repression of tumor necrosis factor (TNF) alpha-stimulated interleukin (IL)-6 expression by the glucocorticoid receptor: a potential mechanism for protection against an excessive inflammatory response

Dexmedetomidine Ameliorates Myocardial Ischemia-Reperfusion Injury by Inhibiting MDH2 Lactylation via Regulating Metabolic Reprogramming

Myocardial ischemia-reperfusion injury (MIRI) significantly worsens the outcomes of patients with cardiovascular diseases. Dexmedetomidine (Dex) is recognized for its cardioprotective properties, but the related mechanisms, especially regarding metabolic reprogramming, have not been fully clarified. A total of 60 patients with heart valve disease are randomly assigned to Dex or control group. Blood samples are collected to analyze cardiac injury biomarkers and metabolomics. In vivo and vitro rat models of MIRI are utilized to assess the effects of Dex on cardiac function, lactate production, and mitochondrial function. It is found that postoperative CK-MB and cTNT levels are significantly lower in the Dex group. Metabolomics reveals that Dex regulates metabolic reprogramming and reduces lactate level. In Dex-treated rats, the myocardial infarction area is reduced, and myocardial contractility is improved. Dex inhibits glycolysis, reduces lactate, and improves mitochondrial function following MIRI. Lactylation proteomics identifies that Dex reduces the lactylation of Malate Dehydrogenase 2（MDH2), thus alleviating myocardial injury. Further studies reveal that MDH2 lactylation induces ferroptosis, leading to MIRI by impairing mitochondrial function. Mechanistic analyses reveal that Dex upregulates Nuclear Receptor Subfamily 3 Group C Member 1（NR3C1) phosphorylation, downregulates Pyruvate Dehydrogenase Kinase 4 (PDK4), and reduces lactate production and MDH2 lactylation. These findings provide new therapeutic targets and mechanisms for the treatment for MIRI.

REDD1 (regulated in development and DNA damage 1) modulates the glucocorticoid receptor function in keratinocytes

Glucocorticoids (GCs) are widely used for the treatment of inflammatory skin diseases despite significant adverse effects including skin atrophy. Effects of GCs are mediated by the glucocorticoid receptor (GR), a well-known transcription factor. Previously, we discovered that one of the GR target genes, REDD1, is causatively involved in skin atrophy. Here, we investigated its role in GR function using HaCaT REDD1 knockout (KO) keratinocytes. We found large differences in transcriptome of REDD1 KO and control Cas9 cells in response to glucocorticoid fluocinolone acetonide (FA): both the scope and amplitude of response were significantly decreased in REDD1 KO. The status of REDD1 did not affect GR stability/degradation during self-desensitization, and major steps in GR activation-its nuclear import and phosphorylation at activating Ser211. However, the amount of GR phosphorylated at Ser226 that may play negative role in GR signalling, was increased in the nuclei of REDD1 KO cells. GR nuclear import and transcriptional activity also depend on the composition of GR chaperone complex: exchange of chaperone FKBP51 (FK506-binding protein 5) for FKBP52 (FK506-binding protein 4) being a necessary step in GR activation. We found the increased expression and abnormal nuclear translocation of FKBP51 in both untreated and FA-treated REDD1 KO cells. Overall, our results suggest the existence of a feed-forward loop in GR signalling mediated by its target gene REDD1, which has translational potential for the development of safer GR-targeted therapies.

Incorporation of a Toll-like receptor 2/6 agonist potentiates mRNA vaccines against cancer and infectious diseases

mRNA vaccines have emerged rapidly in recent years as a prophylactic and therapeutic agent against various diseases including cancer and infectious diseases. Improvements of mRNA vaccines have been underway, among which boosting of efficacy is of great importance. Pam2Cys, a simple synthetic metabolizable lipoamino acid that signals through Toll-like receptor (TLR) 2/6 pathway, eliciting both humoral and cellular adaptive immune responses, is an interesting candidate adjuvant. To investigate the enhancement of the efficacies of mRNA vaccines by Pam2Cys, the adjuvant was incorporated into mRNA-lipid nanoparticles (LNPs) to achieve co-delivery with mRNA. Immunization with the resulting mRNA-LNPs (Pam2Cys) shaped up the immune milieu in the draining lymph nodes (dLNs) through the induction of IL-12 and IL-17, among other cytokines. Antigen presentation was carried out mainly by migratory and dLN-resident conventional type 2 DCs (cDC2s) and significantly more potent antitumor responses were triggered in both prophylactic and therapeutic tumor models in a CD4⁺ and CD8⁺ T cell-dependent fashion. Accompanying memory antitumor immunity was also established. Moreover, the vaccine also stimulated much more robust humoral and cellular immunity in a surrogate COVID-19 prophylactic model. Last but not the least, the new vaccines exhibited good preliminary safety profiles in murine models. These facts warrant future development of Pam2Cys-incorporated mRNA vaccines or relevant mRNA therapeutics for clinical application.

Group 3 innate lymphoid cells secret neutrophil chemoattractants and are insensitive to glucocorticoid via aberrant GR phosphorylation

BACKGROUND

Patients with neutrophil-mediated asthma have poor response to glucocorticoids. The roles and mechanisms of group 3 innate lymphoid cells (ILC3s) in inducing neutrophilic airway inflammation and glucocorticoid resistance in asthma have not been fully clarified.

METHODS

ILC3s in peripheral blood were measured by flow cytometry in patients with eosinophilic asthma (EA) and non-eosinophilic asthma (NEA). ILC3s were sorted and cultured in vitro for RNA sequencing. Cytokines production and signaling pathways in ILC3s after IL-1β stimulation and dexamethasone treatment were determined by real-time PCR, flow cytometry, ELISA and western blot.

RESULTS

The percentage and numbers of ILC3s in peripheral blood was higher in patients with NEA compared with EA, and negatively correlated with blood eosinophils. IL-1β stimulation significantly enhanced CXCL8 and CXCL1 production in ILC3s via activation of p65 NF-κB and p38/JNK MAPK signaling pathways. The expression of neutrophil chemoattractants from ILC3s was insensitive to dexamethasone treatment. Dexamethasone significantly increased phosphorylation of glucocorticoid receptor (GR) at Ser226 but only with a weak induction at Ser211 residues in ILC3s. Compared to human bronchial epithelial cell line (16HBE cells), the ratio of p-GR S226 to p-GR S211 (p-GR S226/S211) was significantly higher in ILC3s at baseline and after dexamethasone treatment. In addition, IL-1β could induce Ser226 phosphorylation and had a crosstalk effect to dexamethasone via NF-κB pathway.

CONCLUSIONS

ILC3s were elevated in patients with NEA, and associated with neutrophil inflammation by release of neutrophil chemoattractants and were glucocorticoid (GC) resistant. This paper provides a novel cellular and molecular mechanisms of neutrophil inflammation and GC-resistance in asthma. Trial registration The study has been prospectively registered in the World Health Organization International Clinical Trials Registry Platform (ChiCTR1900027125).

Corticosteroid resistance in asthma: Cellular and molecular mechanisms

Inhaled glucocorticoids (GCs) are drugs widely used as treatment for asthma patients. They prevent the recruitment and activation of lung immune and inflammatory cells and, moreover, have profound effects on airway structural cells to reverse the effects of disease on airway inflammation. GCs bind to a specific receptor, the glucocorticoid receptor (GR), which is a member of the nuclear receptor superfamily and modulates pro- and anti-inflammatory gene transcription through a number of distinct and complementary mechanisms. Targets genes include many pro-inflammatory mediators such as chemokines, cytokines, growth factors and their receptors. Inhaled GCs are very effective for most asthma patients with little, if any, systemic side effects depending upon the dose. However, some patients show poor asthma control even after the administration of high doses of topical or even systemic GCs. Several mechanisms relating to inflammation have been considered to be responsible for the onset of the relative GC resistance observed in these patients. In these patients, the side-effect profile of GCs prevent continued use of high doses and new drugs are needed. Targeting the defective pathways associated with GC function in these patients may also reactivate GC responsiveness.

The Inflammatory Cytokine Imbalance for Miscarriage, Pregnancy Loss and COVID-19 Pneumonia

Pregnancy can be defined a vascular event upon endocrine control. In the human hemo-chorial placentation the chorionic villi penetrate the wall of the uterine spiral arteries, to provide increasing amounts of nutrients and oxygen for optimal fetal growth. In any physiological pregnancy the natural maternal response is of a Th1 inflammatory type, aimed at avoiding blood loss through the arteriolar wall openings. The control of the vascular function, during gestation as in any other condition, is achieved through the action of two main types of prostanoids: prostaglandin E2 and thromboxane on the one hand (for vasoconstriction and coagulation), prostacyclin on the other (for vasodilation and blood fluidification). The control of the maternal immune response is upon the responsibility of the fetus itself. Indeed, the chorionic villi are able to counteract the natural maternal response, thus changing the inflammatory Th1 type into the anti-inflammatory Th2. Clinical and experimental research in the past half century address to inflammation as the leading cause of abortion, pregnancy loss, premature delivery and related pulmonary, cerebral, intestinal fetal syndromes. Increased level of Interleukin 6, Interleukin 1-beta, Tumor Necrosis Factor-alfa, Interferon-gamma, are some among the well-known markers of gestational inflammation. On the other side, COVID-19 pneumonia is a result of extensive inflammation induced by viral replication within the cells of the respiratory tract. As it may happen in the uterine arteries in the absence of an effective fetal control, viral pneumonia triggers pulmonary vascular coagulation. The cytokines involved in the process are the same as those in gestational inflammation. As the fetus breathes throughout the placenta, fetal death from placental thrombosis is similar to adult death from pulmonary thrombosis. Preventing and counteracting inflammation is mandatory in both conditions. The most relevant literature dealing with the above-mentioned concepts is reviewed in the present article.

Mechanisms behind context-dependent role of glucocorticoids in breast cancer progression

Glucocorticoids (GCs), mostly dexamethasone (dex), are routinely administered as adjuvant therapy to manage side effects in breast cancer. However, recently, it has been revealed that dex triggers different effects and correlates with opposite outcomes depending on the breast cancer molecular subtype. This has raised new concerns regarding the generalized use of GC and suggested that the context-dependent effects of GCs can be taken into potential consideration during treatment design. Based on this, attention has recently been drawn to the role of the glucocorticoid receptor (GR) in development and progression of breast cancer. Therefore, in this comprehensive review, we aimed to summarize the different mechanisms behind different context-dependent GC actions in breast cancer by applying a multilevel examination, starting from the association of variants of the GR-encoding gene to expression at the mRNA and protein level of the receptor, and its interactions with other factors influencing GC action in breast cancer. The role of GCs in chemosensitivity and chemoresistance observed during breast cancer therapy is discussed. In addition, experiences using GC targeting therapeutic options (already used and investigated in preclinical and clinical trials), such as classic GC dexamethasone, selective glucocorticoid receptor agonists and modulators, the GC antagonist mifepristone, and GR coregulators, are also summarized. Evidence presented can aid a better understanding of the biology of context-dependent GC action that can lead to further advances in the personalized therapy of breast cancer by the evaluation of GR along with the conventional estrogen receptor (ER) and progesterone receptor (PR) in the routine diagnostic procedure.

GR-mediated transcriptional regulation of m6A metabolic genes contributes to diet-induced fatty liver in hens

Background

Glucocorticoid receptor (GR) mediated corticosterone-induced fatty liver syndrome (FLS) in the chicken by transactivation of Fat mass and obesity associated gene (FTO), leading to demethylation of N6-methyladenosine (m⁶A) and post-transcriptional activation of lipogenic genes. Nutrition is considered the main cause of FLS in the modern poultry industry. Therefore, this study was aimed to investigate whether GR and m⁶A modification are involved in high-energy and low protein (HELP) diet-induced FLS in laying hens, and if true, what specific m⁶A sites of lipogenic genes are modified and how GR mediates m⁶A-dependent lipogenic gene activation in HELP diet-induced FLS in the chicken.

Results

Laying hens fed HELP diet exhibit excess (P < 0.05) lipid accumulation and lipogenic genes activation in the liver, which is associated with significantly increased (P < 0.05) GR expression that coincided with global m⁶A demethylation. Concurrently, the m⁶A demethylase FTO is upregulated (P < 0.05), whereas the m⁶A reader YTHDF2 is downregulated (P < 0.05) in the liver of FLS chickens. Further analysis identifies site-specific demethylation (P < 0.05) of m⁶A in the mRNA of lipogenic genes, including FASN, SREBP1 and SCD. Moreover, GR binding to the promoter of FTO gene is highly enriched (P < 0.05), while GR binding to the promoter of YTHDF2 gene is diminished (P < 0.05).

Conclusions

These results implicate a possible role of GR-mediated transcriptional regulation of m⁶A metabolic genes on m⁶A-depenent post-transcriptional activation of lipogenic genes and shed new light in the molecular mechanism of FLS etiology in the chicken.

Decoding the temporal nature of brain GR activity in the NFκB signal transition leading to depressive-like behavior

The fine-tuning of neuroinflammation is crucial for brain homeostasis as well as its immune response. The transcription factor, nuclear factor-κ-B (NFκB) is a key inflammatory player that is antagonized via anti-inflammatory actions exerted by the glucocorticoid receptor (GR). However, technical limitations have restricted our understanding of how GR is involved in the dynamics of NFκB in vivo. In this study, we used an improved lentiviral-based reporter to elucidate the time course of NFκB and GR activities during behavioral changes from sickness to depression induced by a systemic lipopolysaccharide challenge. The trajectory of NFκB activity established a behavioral basis for the NFκB signal transition involved in three phases, sickness-early-phase, normal-middle-phase, and depressive-like-late-phase. The temporal shift in brain GR activity was differentially involved in the transition of NFκB signals during the normal and depressive-like phases. The middle-phase GR effectively inhibited NFκB in a glucocorticoid-dependent manner, but the late-phase GR had no inhibitory action. Furthermore, we revealed the cryptic role of basal GR activity in the early NFκB signal transition, as evidenced by the fact that blocking GR activity with RU486 led to early depressive-like episodes through the emergence of the brain NFκB activity. These results highlight the inhibitory action of GR on NFκB by the basal and activated hypothalamic-pituitary-adrenal (HPA)-axis during body-to-brain inflammatory spread, providing clues about molecular mechanisms underlying systemic inflammation caused by such as COVID-19 infection, leading to depression.

Maraviroc, tenofovir disoproxil fumarate and dapivirine, activate progesterone receptor B in the absence of progestogens

Antiretroviral therapy has slowed the HIV/AIDS pandemic and is currently being used as a prophylactic measure for individuals at high risk of infection. However, concerns over adverse effects of long-term use need to be explored. We hypothesize that this may occur, at least in part, through off-target effects via select steroid receptors (SRs) that broadly regulate multiple physiological processes. We investigated the effects of maraviroc (MVC), tenofovir disoproxil fumarate (TDF), and dapivirine (DPV) on progesterone receptor B (PR-B) transcriptional activity. We found that MVC and TDF activate PR-B transcription in the absence of progestogens on a PR-regulated promoter reporter construct and on endogenous PR-regulated genes. MVC and TDF exhibited no direct binding to PR-B; however, increased PR-B phosphorylation was detected with TDF but not MVC. DPV transactivated gilz and ptgs2 in the absence of progestogens and exhibited PR-B binding while showing no effects on phosphorylation, suggesting that it may activate PR-B through a direct mechanism. Our study shows that potential off-target immunomodulatory effects of MVC, TDF and DPV occur in vitro and these are most likely mediated by different mechanisms of PR-B activation.

Reciprocal Modulation of Antiretroviral Drug and Steroid Receptor Function In Vitro

Millions of women are exposed simultaneously to antiretroviral drugs (ARVs) and progestin-based hormonal contraceptives. Yet the reciprocal modulation by ARVs and progestins of their intracellular functions is relatively unexplored. We investigated the effects of tenofovir disoproxil fumarate (TDF) and dapivirine (DPV), alone and in the presence of select steroids and progestins, on cell viability, steroid-regulated immunomodulatory gene expression, activation of steroid receptors, and anti-HIV-1 activity in vitro Both TDF and DPV modulated the transcriptional efficacy of a glucocorticoid agonist via the glucocorticoid receptor (GR) in the U2OS cell line. In TZM-bl cells, DPV induced the expression of the proinflammatory interleukin 8 (IL-8) gene while TDF significantly increased medroxyprogesterone acetate (MPA)-induced expression of the anti-inflammatory glucocorticoid-induced leucine zipper (GILZ) gene. However, peripheral blood mononuclear cell (PBMC) and ectocervical explant tissue viability and gene expression results, along with TZM-bl HIV-1 infection data, are reassuring and suggest that TDF and DPV, in combination with dexamethasone (DEX) or MPA, do not reciprocally modulate key biological effects in primary cells and tissue. We show for the first time that TDF induces progestogen-independent activation of the progesterone receptor (PR) in a cell line. The ability of TDF and DPV to influence GR and PR activity suggests that their use may be associated with steroid receptor-mediated off-target effects. This, together with cell line and individual donor gene expression responses in the primary models, raises concerns that reciprocal modulation may cause side effects in a cell- and donor-specific manner in vivo.

The contraceptive medroxyprogesterone acetate, unlike norethisterone, directly increases R5 HIV-1 infection in human cervical explant tissue at physiologically relevant concentrations

The intramuscular progestin-only injectable contraceptive, depo-medroxyprogesterone acetate (DMPA-IM), is more widely used in Sub-Saharan Africa than another injectable contraceptive, norethisterone enanthate (NET-EN). Epidemiological data show a significant 1.4-fold increased risk of HIV-1 acquisition for DMPA-IM usage, while no such association is shown from limited data for NET-EN. We show that MPA, unlike NET, significantly increases R5-tropic but not X4-tropic HIV-1 replication ex vivo in human endocervical and ectocervical explant tissue from pre-menopausal donors, at physiologically relevant doses. Results support a mechanism whereby MPA, unlike NET, acts via the glucocorticoid receptor (GR) to increase HIV-1 replication in cervical tissue by increasing the relative frequency of CD4+ T cells and activated monocytes. We show that MPA, unlike NET, increases mRNA expression of the CD4 HIV-1 receptor and CCR5 but not CXCR4 chemokine receptors, via the GR. However, increased density of CD4 on CD3+ cells was not observed with MPA by flow cytometry of digested tissue. Results suggest that DMPA-IM may increase HIV-1 acquisition in vivo at least in part via direct effects on cervical tissue to increase founder R5-tropic HIV-1 replication. Our findings support differential biological mechanisms and disaggregation of DMPA-IM and NET-EN regarding HIV-1 acquisition risk category for use in high risk areas.

The stress regulator FKBP51: a novel and promising druggable target for the treatment of persistent pain states across sexes

Supplemental Digital Content is Available in the Text.

Pharmacological blockade of FKBP51 can reduce established persistent pain states across sexes.

It is well established that FKBP51 regulates the stress system by modulating the sensitivity of the glucocorticoid receptor to stress hormones. Recently, we have demonstrated that FKBP51 also drives long-term inflammatory pain states in male mice by modulating glucocorticoid signalling at spinal cord level. Here, we explored the potential of FKBP51 as a new pharmacological target for the treatment of persistent pain across the sexes. First, we demonstrated that FKBP51 regulates long-term pain states of different aetiologies independently of sex. Deletion of FKBP51 reduced the mechanical hypersensitivity seen in joint inflammatory and neuropathic pain states in female and male mice. Furthermore, FKBP51 deletion also reduced the hypersensitivity seen in a translational model of chemotherapy-induced pain. Interestingly, these 3 pain states were associated with changes in glucocorticoid signalling, as indicated by the increased expression, at spinal cord level, of the glucocorticoid receptor isoform associated with glucocorticoid resistance, GR_β, and increased levels of plasma corticosterone. These pain states were also accompanied by an upregulation of interleukin-6 in the spinal cord. Crucially, we were able to pharmacologically reduce the severity of the mechanical hypersensitivity seen in these 3 models of persistent pain with the unique FKBP51 ligand SAFit2. When SAFit2 was combined with a state-of-the-art vesicular phospholipid gel formulation for slow release, a single injection of SAFit2 offered pain relief for at least 7 days. We therefore propose the pharmacological blockade of FKBP51 as a new approach for the treatment of persistent pain across sexes, likely in humans as well as rodents.

Medroxyprogesterone acetate, unlike norethisterone, increases HIV-1 replication in human peripheral blood mononuclear cells and an indicator cell line, via mechanisms involving the glucocorticoid receptor, increased CD4/CD8 ratios and CCR5 levels

High usage of progestin-only injectable contraceptives, which include the intramuscular injectables depo-medroxyprogesterone acetate (DMPA-IM, Depo-Provera) and norethisterone (NET) enanthate (NET-EN or Nur-Isterate), correlates worldwide with areas of high HIV-1 prevalence. Epidemiological data show a significant association between usage of DMPA-IM and increased HIV-1 acquisition but no such association from limited data for NET-EN. Whether MPA and NET have similar effects on HIV-1 acquisition and pathogenesis, and the relationship between these effects and the dose of MPA, are critical issues for women's health and access to suitable and safe contraceptives. We show for the first time that MPA, unlike NET, significantly increases HIV-1 replication in peripheral blood mononuclear cells (PBMCs) and a cervical cell line model. The results provide novel evidence for a biological mechanism whereby MPA, acting via the glucocorticoid receptor (GR), increases HIV-1 replication by at least in part increasing expression of the CCR5 HIV-1 coreceptor on target T-lymphocytes. MPA, unlike NET, also increases activation of T-cells and increases the CD4/CD8 ratio, suggesting that multiple mechanisms are involved in the MPA response. Our data offer strong support for different biological mechanisms for MPA versus NET, due to their differential GR activity. The dose-dependence of the MPA response suggests that significant effects are observed within the range of peak serum levels of progestins in DMPA-IM but not NET-EN users. Dose-response results further suggest that effects of contraceptives containing MPA on HIV-1 acquisition and disease progression may be critically dependent on dose, time after injection and intrinsic factors that affect serum concentrations in women.

GR-regulating Serine/Threonine Kinases: New Physiologic and Pathologic Implications

Glucocorticoid hormones, end products of the hypothalamic-pituitary-adrenal axis, virtually influence all human functions both in a basal homeostatic condition and under stress. The glucocorticoid receptor (GR), a nuclear hormone receptor superfamily protein, mediates these actions of glucocorticoids by acting as a ligand-dependent transcription factor. Because glucocorticoid actions are diverse and strong, many biological pathways adjust them in local tissues by targeting the GR signaling pathway as part of the regulatory loop coordinating complex human functions. Phosphorylation of GR protein by serine/threonine kinases is one of the major regulatory mechanisms for this communication. In this review, recent progress in research investigating GR phosphorylation by these kinases is discussed, along with the possible physiologic and pathophysiologic implications.

A comparative characterization of estrogens used in hormone therapy via estrogen receptor (ER)-α and -β

Conventional hormone therapy (HT) containing estrogens such as ethinylestradiol (EE) have been associated with an increased risk of breast cancer and cardiovascular disease resulting in women seeking safer alternatives that are claimed to have fewer health risks. One such alternative gaining popularity, is custom-compounded bioidentical (b)HT formulations containing bioidentical estradiol (bE₂) and estriol (bE₃). However, the preparation of these custom-compounded estrogens is not regulated, and depending on the route of synthesis, steroid mixtures with differing activities may be produced. Thus, an investigation into the activities of estrogens prepared by custom-compounded pharmacies is warranted. The aim of this study was therefore to directly compare the pharmacological properties of bE₂ and bE₃ of unknown purity relative to commercially available, pure E₂, E₃ and estrone (E₁) standards as well as synthetic EE used in conventional HT via the human estrogen receptor (ER)-α and -β. We determined precise equilibrium dissociation constants (K_d or K_i values) and showed that bE₂ and bE₃ display similar binding affinities to the E₂ and E₃ standards, while EE had a higher affinity for ERα, and E₁ a lower affinity for ERβ. Furthermore, all the estrogens display similar agonist efficacies, but not potencies, for transactivation on a minimal ERE-containing promoter via the individual ER subtypes. Although E₂ and E₃ were equally efficacious and potent on the endogenous ERE-containing pS2 promoter in the MCF-7 BUS breast cancer cell line co-expressing ERα and ERβ, E₁ was less efficacious and potent than E₂. This study is the first to demonstrate that the bioidentical estrogens, commercially available estrogen standards and synthetic EE are full agonists for transrepression on both minimal and endogenous NFκB-containing promoters. Moreover, we showed that these estrogens all increase proliferation and anchorage-independent growth of MCF-7 BUS cells to a similar extent, suggesting that custom-compounded bHT may in fact not be a safer alternative to conventional HT. Furthermore, our results showing that E₃ and E₁ are not weak estrogens, and that E₃ does not antagonize the activity of E₂, suggest that the rationale behind the use of E₃ and E₁ in custom-compounded bHT formulations should be readdressed. Taken together, the results indicating that there is mostly no difference between the custom-compounded bioidentical estrogens, commercially available estrogen standards and synthetic EE, at concentrations reflecting serum levels in women using estrogen-containing HT, suggest that there is no clear advantage in choosing bHT above conventional HT.

Glucocorticoids

The most effective anti-inflammatory drugs used to treat patients with airways disease are topical glucocorticosteroids (GCs). These act on virtually all cells within the airway to suppress airway inflammation or prevent the recruitment of inflammatory cells into the airway. They also have profound effects on airway structural cells to reverse the effects of disease on their function. Glucorticosteroids act via specific receptors-the glucocorticosteroid receptor (GR)-which are a member of the nuclear receptor family. As such, many of the important actions of GCs are to modulate gene transcription through a number of distinct and complementary mechanisms. Targets genes include most inflammatory mediators such as chemokines, cytokines, growth factors and their receptors. GCs delivered by the inhaled route are very effective for most patients and have few systemic side effects. However, in some patients, even high doses of topical or even systemic GCs fail to control their disease. A number of mechanisms relating to inflammation have been reported to be responsible for the failure of these patients to respond correctly to GCs and these provide insight into GC actions within the airways. In these patients, the side-effect profile of GCs prevent continued use of high doses and new drugs are needed for these patients. Targeting the defective pathways associated with GC function in these patients may also reactivate GC responsiveness.

Stress Increases Peripheral Axon Growth and Regeneration through Glucocorticoid Receptor-Dependent Transcriptional Programs

Stress and glucocorticoid (GC) release are common behavioral and hormonal responses to injury or disease. In the brain, stress/GCs can alter neuron structure and function leading to cognitive impairment. Stress and GCs also exacerbate pain, but whether a corresponding change occurs in structural plasticity of sensory neurons is unknown. Here, we show that in female mice (Mus musculus) basal GC receptor (Nr3c1, also known as GR) expression in dorsal root ganglion (DRG) sensory neurons is 15-fold higher than in neurons in canonical stress-responsive brain regions (M. musculus). In response to stress or GCs, adult DRG neurite growth increases through mechanisms involving GR-dependent gene transcription. In vivo, prior exposure to an acute systemic stress increases peripheral nerve regeneration. These data have broad clinical implications and highlight the importance of stress and GCs as novel behavioral and circulating modifiers of neuronal plasticity.

New Insights in Glucocorticoid Receptor Signaling-More Than Just a Ligand-Binding Receptor

The clinical use of classical glucocorticoids (GC) is narrowed by the many side effects it causes and the resistance to GC observed in some diseases. Since the great majority of GC effects depend on the activation of a glucocorticoid receptor (GR), many research groups had focused to better understand the signaling pathways involving those receptors. Transgenic animal models and genetic modifications of the receptor brought a huge insight into GR mechanisms of action. This in turn opened a new window for the search of selective GR modulators that ideally may have agonistic and antagonistic combined effects and activate one specific signaling pathway, inducing mostly transrepression or transactivation mechanisms. Another important research field concerns to posttranslational modifications that affect the GR and consequently also affect its signaling and function. In this mini review, we discuss many of those aspects of GR signaling, as well as findings like the ligand-independent activation of GR, which add another layer of complexity in GR signaling pathways. Although several recent data have been added to the GR field, much work has yet to be done, especially to find out the biological relevance of those alternative GR signaling pathways. Improving the knowledge about alternative GR signaling pathways and understanding how these pathways intercommunicate and in which situations they are relevant might help to develop new strategies to take benefit of it and to improve GC or other compounds efficacy causing minimal side effects.

The stress regulator FKBP51 drives chronic pain by modulating spinal glucocorticoid signaling

Polymorphisms in FKBP51 are associated with stress-related psychiatric disorders and influence the severity of pain symptoms experienced after trauma. We report that FKBP51 (FK506 binding protein 51) is crucial for the full development and maintenance of long-term pain states. Indeed, FKBP51 knockout mice, as well as mice in which silencing of FKBP51 is restricted to the spinal cord, showed reduced hypersensitivity in several persistent pain models in rodents. FKBP51 deletion did not compromise the detection of acute painful stimuli, a critical protective mechanism. Moreover, the intrathecal administration of the specific FKBP51 inhibitor SAFit2 reduced the severity of an established pain state, confirming the crucial role of spinal FKBP51 in nociceptive processing. Finally, glucocorticoid signaling, which is known to modulate persistent pain states in rodents, was impaired in FKBP51 knockout mice. This finding suggested that FKBP51 regulates chronic pain by modulation of glucocorticoid signaling. Thus, FKBP51 is a central mediator of chronic pain, likely in humans as well as rodents, and is a new pharmacologically tractable target for the treatment of long-term pain states.

Glucocorticoid-independent modulation of GR activity: Implications for immunotherapy

Pharmacological doses of glucocorticoids (GCs), acting via the glucocorticoid receptor (GR) to repress inflammation and immune function, remain the most effective therapy in the treatment of inflammatory and immune diseases. Since many patients on GC therapy exhibit GC resistance and severe side-effects, much research is focused on developing more selective GCs and combination therapies, with greater anti-inflammatory potency. GCs mediate their classical genomic transcriptional effects by binding to the cytoplasmic GR, followed by nuclear translocation and modulation of transcription of target genes by direct DNA binding of the GR or its tethering to other transcription factors. Recent evidence suggests, however, that the responses mediated by the GR are much more complex and involve multiple parallel mechanisms integrating simultaneous signals from other receptors, both in the absence and presence of GCs, to shift the sensitivity of a target cell to GCs. The level of cellular stress, immune activation status, or the cell cycle phase may be crucial for determining GC sensitivity and GC responsiveness as well as subcellular localization of the GR and GR levels. Central to the development of new drugs that target GR signaling alone or as add-on therapies, is an in-depth understanding of the molecular mechanisms of GC-independent GR desensitization, priming and activation of the unliganded GR, as well as synergy and cross-talk with other signaling pathways. This review will discuss the information currently available on these topics and their relevance to immunotherapy, as well as identify unanswered questions and future areas of research.

Induction of interferon-λ contributes to TLR3 and RIG-I activation-mediated inhibition of herpes simplex virus type 2 replication in human cervical epithelial cells

STUDY HYPOTHESIS

Is it possible to immunologically activate human cervical epithelial cells to produce antiviral factors that inhibit herpes simplex virus type 2 (HSV-2) replication?

STUDY FINDING

Our results indicate that human cervical epithelial cells possess a functional TLR3/RIG-I signaling system, the activation of which can mount an Interferon-λ (IFN-λ)-mediated anti-HSV-2 response.

WHAT IS KNOWN ALREADY

There is limited information about the role of cervical epithelial cells in genital innate immunity against HSV-2 infection.

STUDY DESIGN, SAMPLES/MATERIALS, METHODS

We examined the expression of toll-like receptors (TLRs) and retinoic acid-inducible I (RIG-I) in End1/E6E7 cells by real-time PCR. The IFN-λ induced by TLR3 and RIG-I activation of End1/E6E7 cells was also examined by real-time PCR and ELISA. HSV-2 infection of End1/E6E7 cells was evaluated by the real-time PCR detection of HSV-2 gD expression. The antibody to IL-10Rβ was used to determine whether IFN-λ contributes to TLR3/RIG-I mediated HSV-2 inhibition. Expression of interferon regulatory factor 3 (IRF3), IRF7, IFN-stimulated gene 56 (ISG56), 2'-5'-oligoadenylate synthetase I (OAS-1) and myxovirus resistance A (MxA) were determined by the real-time PCR and western blot. End1/E6E7 cells were transfected with shRNA to knockdown the IRF3, IRF7 or RIG-I expression. Student's t-test and post Newman-Keuls test were used to analyze stabilized differences in the immunological parameters above between TLR3/RIG-I-activated cells and control cells.

MAIN RESULTS AND THE ROLE OF CHANCE

Human cervical epithelial cells expressed functional TLR3 and RIG-I, which could be activated by poly I:C and 5'ppp double-strand RNAs (5'ppp dsRNA), resulting in the induction of endogenous interferon lambda (IFN-λ). The induced IFN-λ contributed to TLR3/RIG-I-mediated inhibition of HSV-2 replication in human cervical epithelial cells, as an antibody to IL-10Rβ, an IFN-λ receptor subunit, could compromise TLR3/RIG-I-mediated inhibition of HSV-2. Further studies showed that TLR3/RIG-I signaling in the cervical epithelial cells by dsRNA induced the expression of the IFN-stimulated genes (ISGs), ISG56, 2'-5'-oligoadenylate synthetase I (OAS-1) and myxovirus resistance A (MxA), the key antiviral elements in the IFN signaling pathway. In addition, we observed that the topical treatment of genital mucosa with poly I:C could protect mice from genital HSV-2 infection.

LIMITATIONS, REASONS FOR CAUTION

Future prospective studies with primary cells and suitable animal models are needed in order to confirm these outcomes.

WIDER IMPLICATIONS OF THE FINDINGS

The findings provide direct and compelling evidence that there is intracellular expression and regulation of IFN-λ in human cervical epithelial cells, which may have a key role in the innate genital protection against viral infections.

LARGE SCALE DATA

Not applicable.

STUDY FUNDING AND COMPETING INTERESTS

This work was supported by the National Natural Science Foundation of China (81301428 to L.Z. and 81271334 to W.-Z.H.), the Fundamental Research Funds for the Central Universities (2042015kf0188 to L.Z.), the China Postdoctoral Science Foundation (2013M531745 to L.Z.), the Development Program of China ('973', 2012CB518900 to W.-Z.H.) from the Ministry of Science and Technology of the People's Republic of China, grants (DA12815 and DA022177 to W.-Z.H.) from the National Institute on Drug Abuse (NIDA) and the open project of Hubei Key Laboratory of Wudang Local Chinese Medicine Research (WDCM005 to M.S.). The authors declare no competing financial interests.

Dexamethasone attenuates the embryotoxic effect of endometriotic peritoneal fluid in a murine model

PURPOSE

The in vitro fertilization (IVF) pregnancy rate of women with advanced stage endometriosis is nearly half that of the general population, suggesting incomplete targeting of the pathophysiology underlying endometriosis-associated infertility. Compelling evidence highlights inflammation as the etiologic link between endometriosis and infertility and a potential target for adjunctive treatment. The objective of this study was to examine the effect of dexamethasone on murine embryos exposed to human endometriotic peritoneal fluid (PF) using the established murine embryo assay model.

METHODS

PF was obtained from women with and without severe endometriosis. Murine embryos were harvested and randomly allocated to five groups of culture media conditions: (1) human tubal fluid (HTF), (2) HTF and 10 % PF from women without endometriosis, (3) HTF and 10 % PF from women with endometriosis (PF-E), (4) HTF with PF-E and 0.01 mcg/mL dexamethasone, and (5) HTF with PF-E and 0.1 mcg/mL dexamethasone. Embryos were cultured in standard conditions and evaluated for blastocyst development.

RESULTS

A total of 266 mouse embryos were cultured. Baseline blastulation rates were 63.6 %. The addition of peritoneal fluid from women with endometriosis decreased the blastocyst development rate to 38.9 % (P = 0.008). The addition of 0.1 mcg/mL of dexamethasone to the culture media restored the blastulation rate to near baseline levels (61.2 %; P = 0.019).

CONCLUSIONS

The results of our in vitro study demonstrate the capacity of dexamethasone to mitigate the deleterious impact of endometriotic PF on embryo development. If confirmed in vivo, dexamethasone may prove a useful adjunct for the treatment of endometriosis-associated infertility.

Minireview: Tipping the balance: ligand-independent activation of steroid receptors

Steroid receptors are prototypical ligand-dependent transcription factors and a textbook example for allosteric regulation. According to this canonical model, binding of cognate steroid is an absolute requirement for transcriptional activation. Remarkably, the simple one ligand-one receptor model could not be farther from the truth. Steroid receptors, notably the sex steroid receptors, can receive multiple inputs. Activation of steroid receptors by other signals, working through their own signaling pathways, in the absence of the cognate steroids, represents the most extreme form of signaling cross talk. Compared with cognate steroids, ligand-independent activation pathways produce similar but not identical outputs. Here we review the phenomena and discuss what is known about the underlying molecular mechanisms and the biological significance. We hypothesize that steroid receptors may have evolved to be trigger happy. In addition to their cognate steroids, many posttranslational modifications and interactors, modulated by other signals, may be able to tip the balance.

Systems pharmacology of mifepristone (RU486) reveals its 47 hub targets and network: comprehensive analysis and pharmacological focus on FAK-Src-Paxillin complex

Mifepristone (RU486), a synthetic steroid compound used as an abortifacient drug, has received considerable attention to its anticancer activity recently. To explore the possibility of using mifepristone as a cancer metastasis chemopreventive, we performed a systems pharmacology analysis of mifepristone-related molecules in the present study. Data were collected by using Natural Language Processing (NLP) and 513 mifepristone-related genes were dug out and classified functionally using a gene ontology (GO) hierarchy, followed by KEGG pathway enrichment analysis. Potential signal pathways and targets involved in cancer were obtained by integrative network analysis. Total thirty-three proteins were involved in focal adhesion-the key signaling pathway associated with cancer metastasis. Molecular and cellular assays further demonstrated that mifepristone had the ability to prevent breast cancer cells from migration and interfere with their adhesion to endothelial cells. Moreover, mifepristone inhibited the expression of focal adhesion kinase (FAK), paxillin, and the formation of FAK/Src/Paxillin complex, which are correlated with cell adhesion and migration. This study set a good example to identify chemotherapeutic potential seamlessly from systems pharmacology to cellular pharmacology, and the revealed hub genes may be the promising targets for cancer metastasis chemoprevention.

Medroxyprogesterone acetate differentially regulates interleukin (IL)-12 and IL-10 in a human ectocervical epithelial cell line in a glucocorticoid receptor (GR)-dependent manner

Medroxyprogesterone acetate (MPA), designed to mimic the actions of the endogenous hormone progesterone (P4), is extensively used by women as a contraceptive and in hormone replacement therapy. However, little is known about the steroid receptor-mediated molecular mechanisms of action of MPA in the female genital tract. In this study, we investigated the regulation of the pro-inflammatory cytokine, interleukin (IL)-12, and the anti-inflammatory cytokine IL-10, by MPA versus P4, in an in vitro cell culture model of the female ectocervical environment. This study shows that P4 and MPA significantly increase the expression of the IL-12p40 and IL-12p35 genes, whereas IL-10 gene expression is suppressed in a dose-dependent manner. Moreover, these effects were abrogated when reducing the glucocorticoid receptor (GR) levels with siRNA. Using a combination of chromatin immunoprecipitation (ChIP), siRNA, and re-ChIP assays, we show that recruitment of the P4- and MPA-bound GR to the IL-12p40 promoter requires CCAAT enhancer-binding protein (C/EBP)-β and nuclear factor κB (NFκB), although recruitment to the IL-10 promoter requires signal transducer and activator of transcription (STAT)-3. These results suggest that both P4 and MPA may modulate inflammation in the ectocervix via this genomic mechanism.

The injectable-only contraceptive medroxyprogesterone acetate, unlike norethisterone acetate and progesterone, regulates inflammatory genes in endocervical cells via the glucocorticoid receptor

Clinical studies suggest that the injectable contraceptive medroxyprogesterone acetate (MPA) increases susceptibility to infections such as HIV-1, unlike the injectable contraceptive norethisterone enanthate (NET-EN). We investigated the differential effects, molecular mechanism of action and steroid receptor involvement in gene expression by MPA as compared to NET and progesterone (P4) in the End1/E6E7 cell line model for the endocervical epithelium, a key point of entry for pathogens in the female genital mucosa. MPA, unlike NET-acetate (NET-A) and P4, increases mRNA expression of the anti-inflammatory GILZ and IκBα genes. Similarly, MPA unlike NET-A, decreases mRNA expression of the pro-inflammatory IL-6, IL-8 and RANTES genes, and IL-6 and IL-8 protein levels. The predominant steroid receptor expressed in the End1/E6E7 and primary endocervical epithelial cells is the glucocorticoid receptor (GR), and GR knockdown experiments show that the anti-inflammatory effects of MPA are mediated by the GR. Chromatin-immunoprecipitation results suggest that MPA, unlike NET-A and P4, represses pro-inflammatory cytokine gene expression in cervical epithelial cells via a mechanism involving recruitment of the GR to cytokine gene promoters, like the GR agonist dexamethasone. This is at least in part consistent with direct effects on transcription, without a requirement for new protein synthesis. Dose response analysis shows that MPA has a potency of ∼24 nM for transactivation of the anti-inflammatory GILZ gene and ∼4–20 nM for repression of the pro-inflammatory genes, suggesting that these effects are likely to be relevant at injectable contraceptive doses of MPA. These findings suggest that in the context of the genital mucosa, these GR-mediated glucocorticoid-like effects of MPA in cervical epithelial cells are likely to play a critical role in discriminating between the effects on inflammation caused by different progestins and P4 and hence susceptibility to genital infections, given the predominant expression of the GR in primary endocervical epithelial cells.

Basal p38 mitogen-activated protein kinase regulates unliganded glucocorticoid receptor function in airway smooth muscle cells

Like many steroid receptors, the glucocorticoid (GC) receptor (GR) is a phosphoprotein. Although there are multiple phosphorylation sites critical for GR transcriptional activity (i.e., serine [S]203, S211, and S226), their respective role in driving GR functions is highly cell specific. We have recently identified protein phosphatase 5 as an essential Ser/Thr phosphatase responsible for impairing GR function via S211 dephosphorylation in airway smooth muscle (ASM) cells. Because p38 mitogen-activated protein kinase (MAPK) directly phosphorylates GR in different cell types in a stimulus- and cell-dependent manner, we investigated the role of p38 MAPK on GR phosphorylation and function in ASM cells. Cells were transfected with 100 nM p38 MAPK small interfering RNA or 2 μg MAPK kinase 3 expression vector (a specific kinase that directly activates p38 MAPK) in the presence or absence of fluticasone (100 nM) and/or p38 MAPK pharmacological inhibitor SB203580. We found that p38 MAPK blockade positively regulates GR nuclear translocation and GR-dependent induction of the steroid-target gene GC-induced leucine zipper in a hormone-independent manner. We also found that p38 MAPK-dependent regulation of GR functions was associated with a differential action on GR phosphorylation at S203 and S211 residues. This study demonstrated that the inactive state of GR in resting conditions is not only ensured by the absence of the GC ligand but also by p38 MAPK-dependent phosphorylation of unliganded GR at specific residues, which appears to be important in determining the overall GC responsiveness of ASM cells.

Expression microarray identifies the unliganded glucocorticoid receptor as a regulator of gene expression in mammary epithelial cells

Background

While glucocorticoids and the liganded glucocorticoid receptor (GR) have a well-established role in the maintenance of differentiation and suppression of apoptosis in breast tissue, the involvement of unliganded GR in cellular processes is less clear. Our previous studies implicated unliganded GR as a positive regulator of the BRCA1 tumour suppressor gene in the absence of glucocorticoid hormone, which suggested it could play a similar role in the regulation of other genes.

Methods

An shRNA vector directed against GR was used to create mouse mammary cell lines with depleted endogenous levels of this receptor in order to further characterize the role of GR in breast cells. An expression microarray screen for targets of unliganded GR was performed using our GR-depleted cell lines maintained in the absence of glucocorticoids. Candidate genes positively regulated by unliganded GR were identified, classified by Gene Ontology and Ingenuity Pathway Analysis, and validated using quantitative real-time reverse transcriptase PCR. Chromatin immunoprecipitation and dual luciferase expression assays were conducted to further investigate the mechanism through which unliganded GR regulates these genes.

Results

Expression microarray analysis revealed 260 targets negatively regulated and 343 targets positively regulated by unliganded GR. A number of the positively regulated targets were involved in pro-apoptotic networks, possibly opposing the activity of liganded GR targets. Validation and further analysis of five candidates from the microarray indicated that two of these, Hsd11b1 and Ch25h, were regulated by unliganded GR in a manner similar to Brca1 during glucocorticoid treatment. Furthermore, GR was shown to interact directly with and upregulate the Ch25h promoter in the absence, but not the presence, of hydrocortisone (HC), confirming our previously described model of gene regulation by unliganded GR.

Conclusion

This work presents the first identification of targets of unliganded GR. We propose that the balance between targets of liganded and unliganded GR signaling is responsible for controlling differentiation and apoptosis, respectively, and suggest that gene regulation by unliganded GR may represent a mechanism for reducing the risk of breast tumourigenesis by the elimination of abnormal cells.

Markers of inflammation and stress distinguish subsets of individuals with schizophrenia and bipolar disorder

Schizophrenia and bipolar disorder share a number of common features, both symptomatically and biologically. Abnormalities in the neuroimmune and the stress-signaling pathways have been previously identified in brains of individuals with both diseases. However, the possible relationship between abnormalities in stress and neuroimmune signaling within the cortex of people with psychotic illness has not been defined. To test the hypothesis that combined alterations in brain stress responsiveness and neuroimmune/inflammatory status are characteristic of some individuals suffering from major mental illness, we examined gene expression in the Stanley Array Cohort of 35 controls, 35 individuals with schizophrenia and 34 individuals with bipolar disorder. We used levels of 8 inflammatory-related transcripts, of which SERPINA3 was significantly elevated in individuals with schizophrenia (F(2,88)=4.137, P<0.05), and 12 glucocorticoid receptor signaling (stress) pathway transcripts previously examined, to identify two clusters of individuals: a high inflammation/stress group (n=32) and a low (n=68) inflammation/stress group. The high inflammation/stress group has a significantly greater number of individuals with schizophrenia (n=15), and a trend toward having more bipolar disorder individuals (n=11), when compared with controls (n=6). Using these subgroups, we tested which microarray-assessed transcriptional changes may be associated with high inflammatory/stress groups using ingenuity analysis and found that an extended network of gene expression changes involving immune, growth factors, inhibitory signaling and cell death factors also distinguished these groups. Our work demonstrates that some of the heterogeneity in schizophrenia and bipolar disorder may be partially explained by inflammation/stress interactions, and that this biological subtype cuts across Diagnostic and Statistical Manual of Mental Disorders (DSM)-defined categories.

Lipid raft- and protein kinase C-mediated synergism between glucocorticoid- and gonadotropin-releasing hormone signaling results in decreased cell proliferation

Cross-talk between the glucocorticoid receptor (GR) and other receptors is emerging as a mechanism for fine-tuning cellular responses. We have previously shown that gonadotropin-releasing hormone (GnRH) ligand-independently activates the GR and synergistically modulates glucocorticoid-induced transcription of an endogenous gene in LβT2 pituitary gonadotrope precursor cells. Here, we investigated GR and GnRH receptor (GnRHR) cross-talk that involves co-localization with lipid rafts in LβT2 cells. We report that the GnRHR and a small population of the GR co-localize with the lipid raft protein flotillin-1 (Flot-1) at the plasma membrane and that the GR is present in a complex with Flot-1, independent of the presence of ligands. We found that the SGK-1 gene is up-regulated by Dex and GnRH alone, whereas a combination of both ligands resulted in a synergistic increase in SGK-1 mRNA levels. Using siRNA-mediated knockdown and antagonist strategies, we show that the gene-specific synergistic transcriptional response requires the GR, GnRHR, and Flot-1 as well as the protein kinase C pathway. Interestingly, although several GR cofactors are differentially recruited to the SGK-1 promoter in the presence of Dex and GnRH, GR levels remain unchanged compared with Dex treatment alone, suggesting that lipid raft association of the GR has a role in enhancing its transcriptional output in the nucleus. Finally, we show that Dex plus GnRH synergistically inhibit cell proliferation in a manner dependent on SGK-1 and Flot-1. Collectively the results support a mechanism whereby GR and GnRHR cross-talk within Flot-1-containing lipid rafts modulates cell proliferation via PKC activation and SGK-1 up-regulation.

Impact of glucocorticoid receptor density on ligand-independent dimerization, cooperative ligand-binding and basal priming of transactivation: a cell culture model

Glucocorticoid receptor (GR) levels vary between tissues and individuals and are altered by physiological and pharmacological effectors. However, the effects and implications of differences in GR concentration have not been fully elucidated. Using three statistically different GR concentrations in transiently transfected COS-1 cells, we demonstrate, using co-immunoprecipitation (CoIP) and fluorescent resonance energy transfer (FRET), that high levels of wild type GR (wtGR), but not of dimerization deficient GR (GRdim), display ligand-independent dimerization. Whole-cell saturation ligand-binding experiments furthermore establish that positive cooperative ligand-binding, with a concomitant increased ligand-binding affinity, is facilitated by ligand-independent dimerization at high concentrations of wtGR, but not GRdim. The down-stream consequences of ligand-independent dimerization at high concentrations of wtGR, but not GRdim, are shown to include basal priming of the system as witnessed by ligand-independent transactivation of both a GRE-containing promoter-reporter and the endogenous glucocorticoid (GC)-responsive gene, GILZ, as well as ligand-independent loading of GR onto the GILZ promoter. Pursuant to the basal priming of the system, addition of ligand results in a significantly greater modulation of transactivation potency than would be expected solely from the increase in ligand-binding affinity. Thus ligand-independent dimerization of the GR at high concentrations primes the system, through ligand-independent DNA loading and transactivation, which together with positive cooperative ligand-binding increases the potency of GR agonists and shifts the bio-character of partial GR agonists. Clearly GR-levels are a major factor in determining the sensitivity to GCs and a critical factor regulating transcriptional programs.

Pro-asthmatic cytokines regulate unliganded and ligand-dependent glucocorticoid receptor signaling in airway smooth muscle

To elucidate the regulation of glucocorticoid receptor (GR) signaling under pro-asthmatic conditions, cultured human airway smooth muscle (HASM) cells were treated with proinflammatory cytokines or GR ligands alone and in combination, and then examined for induced changes in ligand-dependent and -independent GR activation and downstream signaling events. Ligand stimulation with either cortisone or dexamethsone (DEX) acutely elicited GR translocation to the nucleus and, comparably, ligand-independent stimulation either with the Th2 cytokine, IL-13, or the pleiotropic cytokine combination, IL-1β/TNFα, also acutely evoked GR translocation. The latter response was potentiated by combined exposure of cells to GR ligand and cytokine. Similarly, treatment with either DEX or IL-13 alone induced GR phosphorylation at its serine-211 residue (GR^Ser211), denoting its activated state, and combined treatment with DEX+IL-13 elicited heightened and sustained GR^Ser211 phosphorylation. Interestingly, the above ligand-independent GR responses to IL-13 alone were not associated with downstream GR binding to its consensus DNA sequence or GR transactivation, whereas both DEX-induced GR:DNA binding and transcriptional activity were significantly heightened in the presence of IL-13, coupled to increased recruitment of the transcriptional co-factor, MED14. The stimulated GR signaling responses to DEX were prevented in IL-13-exposed cells wherein GR^Ser211 phosphorylation was suppressed either by transfection with specific serine phosphorylation-deficient mutant GRs or treatment with inhibitors of the MAPKs, ERK1/2 and JNK. Collectively, these novel data highlight a heretofore-unidentified homeostatic mechanism in HASM cells that involves pro-asthmatic cytokine-driven, MAPK-mediated, non-ligand-dependent GR activation that confers heightened glucocorticoid ligand-stimulated GR signaling. These findings raise the consideration that perturbations in this homeostatic cytokine-driven GR signaling mechanism may be responsible, at least in part, for the insensirtivity to glucocorticoid therapy that is commonly seen in individuals with severe asthma.

Polymorphisms of the Interleukin 6 gene contribute to cervical cancer susceptibility in Eastern Chinese women

Interleukin 6 (IL6) encodes a cytokine protein, which functions in inflammation, maintains immune homeostasis and plays important roles in cervical carcinogenesis. Single nucleotide polymorphisms (SNPs) in IL6 that cause variations in host immune response may contribute to cervical cancer risk. In this two-stage case-control study with a total of 1,584 cervical cancer cases and 1,768 cancer-free female controls, we investigated associations between two IL6 SNPs and cervical cancer risk in Eastern Chinese women. In both Study 1 and Study 2, we found a significant association of the IL6-rs2069837 SNP with an increased risk of cervical cancer as well as in their combined data (OR 1.27 and 1.19, 95% CI 1.08-1.49 and 1.04-1.36, P = 0.004 and 0.014 for dominant and additive genetic models, respectively). Furthermore, rs2069837 variant AG/GG carriers showed significantly higher levels of IL6 protein than did rs2069837 AA carriers in the target tissues. Using multifactor dimensionality reduction (MDR) and classification and regression tree (CART) analyses, we observed some evidence of interactions of the IL6 rs2069837 SNP with age at primiparity and menopausal status in cervical cancer risk. We concluded that the IL6-rs2069837 SNP may be a marker for susceptibility to cervical cancer in Eastern Chinese women by a possible mechanism of altering the IL6 protein expression. Although lacked information on human papillomavirus (HPV) infection, our study also suggested possible interactions between IL6 genotypes and age at primiparity or menopausal status in cervical carcinogenesis. However, larger, independent studies with detailed HPV infection data are warranted to validate our findings.

Corticosteroid-dependent plasticity mediates compulsive alcohol drinking in rats

Alcoholism is characterized by a compulsion to seek and ingest alcohol, loss of control over intake, and the emergence of a negative emotional state during abstinence. We hypothesized that sustained activation of neuroendocrine stress systems (e.g., corticosteroid release via the hypothalamic-pituitary-adrenal axis) by alcohol intoxication and withdrawal and consequent alterations in glucocorticoid receptor (GR) and mineralocorticoid receptor (MR) activation drive compulsive alcohol drinking. Our results showed that rats exposed to alcohol vapor to the point of dependence displayed increased alcohol intake, compulsive drinking measured by progressive-ratio responding, and persistent alcohol consumption despite punishment, assessed by adding quinine to the alcohol solution, compared with control rats that were not exposed to alcohol vapor. No group differences were observed in the self-administration of saccharin-sweetened water. Acute alcohol withdrawal was accompanied by downregulated GR mRNA in various stress/reward-related brain regions [i.e., prefrontal cortex, nucleus accumbens (NAc), and bed nucleus of the stria terminalis (BNST)], whereas protracted alcohol abstinence was accompanied by upregulated GR mRNA in the NAc core, ventral BNST, and central nucleus of the amygdala. No significant alterations in MR mRNA levels were found. Chronic GR antagonism with mifepristone (RU38486) prevented the escalation of alcohol intake and compulsive responding induced by chronic, intermittent alcohol vapor exposure. Chronic treatment with mifepristone also blocked escalated alcohol drinking and compulsive responding during protracted abstinence. Thus, the GR system appears to be involved in the development of alcohol dependence and may represent a potential pharmacological target for the treatment of alcoholism.

The unliganded glucocorticoid receptor positively regulates the tumor suppressor gene BRCA1 through GABP beta

Loss of BRCA1 tumor suppressor function is a critical event in breast tumorigenesis. We have previously identified the stress hormone hydrocortisone as a negative regulator of BRCA1 expression in nonmalignant mammary cells. Here, we have identified a direct role for the unliganded glucocorticoid receptor (GR) in BRCA1 upregulation in the absence of hydrocortisone. The positive regulatory effect of GR is lost upon the addition of hydrocortisone. We have shown that GR interacts with the BRCA1 promoter only in the absence of hydrocortisone, and that this interaction is mediated through the β-subunit of the ets transcription factor GA-binding protein (GABP) at the RIBS promoter element. GR and GABPβ interact in both coimmunoprecipitation and mammalian two-hybrid assays, and this interaction involves the N-terminal to central regions of both proteins. This work presents the first evidence of a ligand-independent role for GR as a positive regulator of gene expression, and loss of GR from the BRCA1 promoter in response to stress hormones leads to decreased BRCA1 expression. Because low levels of BRCA1 have been implicated in the development of sporadic breast cancer, this may represent a novel mechanism through which prolonged stress signaling increases breast cancer risk.

Cell cycle phase regulates glucocorticoid receptor function

The glucocorticoid receptor (GR) is a member of the nuclear hormone receptor superfamily of ligand-activated transcription factors. In contrast to many other nuclear receptors, GR is thought to be exclusively cytoplasmic in quiescent cells, and only translocate to the nucleus on ligand binding. We now demonstrate significant nuclear GR in the absence of ligand, which requires nuclear localisation signal 1 (NLS1). Live cell imaging reveals dramatic GR import into the nucleus through interphase and rapid exclusion of the GR from the nucleus at the onset of mitosis, which persists into early G(1). This suggests that the heterogeneity in GR distribution is reflective of cell cycle phase. The impact of cell cycle-driven GR trafficking on a panel of glucocorticoid actions was profiled. In G2/M-enriched cells there was marked prolongation of glucocorticoid-induced ERK activation. This was accompanied by DNA template-specific, ligand-independent GR transactivation. Using chimeric and domain-deleted receptors we demonstrate that this transactivation effect is mediated by the AF1 transactivation domain. AF-1 harbours multiple phosphorylation sites, which are consensus sequences for kinases including CDKs, whose activity changes during the cell cycle. In G2/M there was clear ligand independent induction of GR phosphorylation on residues 203 and 211, both of which are phosphorylated after ligand activation. Ligand-independent transactivation required induction of phospho-S211GR but not S203GR, thereby directly linking cell cycle driven GR modification with altered GR function. Cell cycle phase therefore regulates GR localisation and post-translational modification which selectively impacts GR activity. This suggests that cell cycle phase is an important determinant in the cellular response to Gc, and that mitotic index contributes to tissue Gc sensitivity.