Pathophysiology of modulation of local glucocorticoid levels by 11beta-hydroxysteroid dehydrogenases

Population Target-Mediated Pharmacokinetic/Pharmacodynamic Modeling to Evaluate SPI-62 Exposure and Hepatic 11β-Hydroxysteroid Dehydrogenase Type 1 (HSD-1) Inhibition in Healthy Adults

INTRODUCTION

SPI-62 is a small-molecule 11β-hydroxysteroid dehydrogenase type 1 (HSD-1) inhibitor exhibiting complicated nonlinear pharmacokinetics (PK) in human. Previously, we developed a target-mediated drug disposition (TMDD) model to characterize the substantial nonlinear PK of SPI-62.

OBJECTIVE

The aim of the current analysis was to perform population PK/PD analysis to further link SPI-62 exposure (i.e., PK) with its response (i.e., inhibition of hepatic HSD-1 activity) to gain a quantitative understanding of the SPI-62 dose-exposure-response relationship.

METHODS

PK and PD data from the first-in-human (FIH) clinical trials, including single ascending dose (SAD) and multiple ascending dose (MAD) studies, were used for model development. During the model development process, the final model selection was based on biological and physiological plausibility, goodness-of-fit plots, stability of parameter estimates, and objective function value. The nonlinear-mixed effect modeling (NONMEM) software was used for both the implementation of the PK/PD model and model simulation. SPI-62 plasma levels and hepatic HSD-1 inhibition over time following various dose regimens were simulated.

RESULTS

The final model was a two-compartment TMDD model component for SPI-62 and an inhibitory Imax model component for hepatic HSD-1 activity. The TMDD-hepatic PD model that we established adequately characterized all remarkable PK and PD behaviors of SPI-62, such as extremely low plasma exposures following the first low doses, nonlinear PK turned into linear PK after repeated low doses, and substantial and long-lasting hepatic HSD-1 inhibition following low doses. SPI-62 was estimated to bind to the target with a second-order association rate constant (Kon) of 8.43 nM-1 h-1 and first-order dissociation rate constant (Koff) value of 0.229 h-1, indicating that SPI-62 binds rapidly to, and dissociates slowly from, its pharmacological target. The estimated target capacity (Rtot) of 5460 nmol corresponds to approximately 2.2 mg of SPI-62, which comports well with the dose range in which PK nonlinearity is prominent. Model simulation results reveal that a 6 mg once-daily regimen can lead to long-lasting and substantial hepatic HSD-1 inhibition.

CONCLUSIONS

A population TMDD-PD model that explains SPI-62 nonlinear PK and hepatic HSD-1 inhibition following different dose regimens in healthy adults was successfully established. Our simulation results provide a solid foundation for model-informed development of SPI-62.

Hyperandrogenism and Its Possible Effects on Endometrial Receptivity: A Review

Endometrial receptivity is a state of the endometrium defined by its readiness for embryo implantation. When the receptivity of the endometrium is impaired due to hyperandrogenism or androgen excess, this condition can lead to pregnancy loss or infertility. Hyperandrogenism encompasses a wide range of clinical manifestations, including polycystic ovary syndrome (PCOS), idiopathic hirsutism, hirsutism and hyperandrogaenemia, non-classical congenital adrenal hyperplasia, hyperandrogenism, insulin resistance, acanthosis nigricans (HAIR-AN), ovarian or adrenal androgen-secreting neoplasms, Cushing's syndrome, and hyperprolactinaemia. Recurrent miscarriages have been shown to be closely related to elevated testosterone levels, which alter the endometrial milieu so that it is less favourable for embryo implantation. There are mechanisms for endometrial receptivity that are affected by excess androgen. The HOXA gene, aVβ3 integrin, CDK signalling pathway, MECA-79, and MAGEA-11 were the genes and proteins affect endometrial receptivity in the presence of a hyperandrogenic state. In this review, we would like to explore the other manifestations of androgen excess focusing on causes other than PCOS and learn possible mechanisms of endometrial receptivity behind androgen excess leading to pregnancy loss or infertility.

Impaired alveolar macrophage 11β-hydroxysteroid dehydrogenase type 1 reductase activity contributes to increased pulmonary inflammation and mortality in sepsis-related ARDS

Background

Acute Respiratory Distress Syndrome (ARDS) is a devastating pulmonary inflammatory disorder, commonly precipitated by sepsis. Glucocorticoids are immunomodulatory steroids that can suppress inflammation. Their anti-inflammatory properties within tissues are influenced by their pre-receptor metabolism and amplification from inactive precursors by 11β-hydroxysteroid dehydrogenase type-1 (HSD-1). We hypothesised that in sepsis-related ARDS, alveolar macrophage (AM) HSD-1 activity and glucocorticoid activation are impaired, and associated with greater inflammatory injury and worse outcomes.

Methods

We analysed broncho-alveolar lavage (BAL) and circulating glucocorticoid levels, AM HSD-1 reductase activity and Receptor for Advanced Glycation End-products (RAGE) levels in two cohorts of critically ill sepsis patients, with and without ARDS. AM HSD-1 reductase activity was also measured in lobectomy patients. We assessed inflammatory injury parameters in models of lung injury and sepsis in HSD-1 knockout (KO) and wild type (WT) mice.

Results

No difference in serum and BAL cortisol: cortisone ratios are shown between sepsis patients with and without ARDS. Across all sepsis patients, there is no association between BAL cortisol: cortisone ratio and 30-day mortality. However, AM HSD-1 reductase activity is impaired in patients with sepsis-related ARDS, compared to sepsis patients without ARDS and lobectomy patients (0.075 v 0.882 v 0.967 pM/hr/106 AMs, p=0.004). Across all sepsis patients (with and without ARDS), impaired AM HSD-1 reductase activity is associated with defective efferocytosis (r=0.804, p=0.008) and increased 30-day mortality. AM HSD-1 reductase activity negatively correlates with BAL RAGE in sepsis patients with ARDS (r=-0.427, p=0.017). Following intra-tracheal lipopolysaccharide (IT-LPS) injury, HSD-1 KO mice demonstrate increased alveolar neutrophil infiltration, apoptotic neutrophil accumulation, alveolar protein permeability and BAL RAGE concentrations compared to WT mice. Caecal Ligation and Puncture (CLP) injury in HSD-1 KO mice results in greater peritoneal apoptotic neutrophil accumulation compared to WT mice.

Conclusions

AM HSD-1 reductase activity does not shape total BAL and serum cortisol: cortisone ratios, however impaired HSD-1 autocrine signalling renders AMs insensitive to the anti-inflammatory effects of local glucocorticoids. This contributes to the decreased efferocytosis, increased BAL RAGE concentrations and mortality seen in sepsis-related ARDS. Upregulation of alveolar HSD-1 activity could restore AM function and improve clinical outcomes in these patients.

11β-Hydroxysteroid Dehydrogenase Type 1 as a Potential Treatment Target in Cardiovascular Diseases

Glucocorticoids (GCs) belong to the group of steroid hormones. Their representative in humans is cortisol. GCs are involved in most physiological processes of the body and play a significant role in important biological processes, including reproduction, growth, immune responses, metabolism, maintenance of water and electrolyte balance, functioning of the central nervous system and the cardiovascular system. The availability of cortisol to the glucocorticoid receptor is locally controlled by the enzyme 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1). Evidence of changes in intracellular GC metabolism in the pathogenesis of obesity, metabolic syndrome (MetS) and cardiovascular complications highlights the role of selective 11β-HSD1 inhibition in the pharmacotherapy of these diseases. This paper discusses the role of 11β-HSD1 in MetS and its cardiovascular complications and the importance of selective inhibition of 11β-HSD1.

Transient expansion of the expression region of Hsd11b1, encoding 11β-hydroxysteroid dehydrogenase type 1, in the developing mouse neocortex

Corticosteroids are stress-related hormones that maintain homeostasis. The most effective corticosteroids are corticosterone (CORT) in rodents and cortisol in primates. 11β-Hydroxysteroid dehydrogenase type 1 (11β-HSD1; EC 1.1.1.146), encoded by Hsd11b1, is a key regulator of the local concentration of CORT/cortisol. Hsd11b1 expression in layer 5 of the primary somatosensory cortex has been shown in adult mice. However, its localization in the entire neocortex, especially during development, has not been fully addressed. Here, we established robust and dynamic expression profiles of Hsd11b1 in the developing mouse neocortex. Hsd11b1 was found mostly in pyramidal neurons. By retrograde tracing, we observed that some Hsd11b1-positive cells were projection neurons, indicating that at least some were excitatory. At postnatal day 0 (P0), Hsd11b1 was expressed in the deep layer of the somatosensory cortex. Then, from P3 to P8, the expression area expanded broadly; it was observed in layers 4 and 5, spanning the whole neocortex, including the primary motor cortex (M1) and the primary visual cortex (V1). The positive region gradually narrowed from P14 onwards and was ultimately limited to layer 5 of the somatosensory cortex at P26 and later. Furthermore, we administered CORT to nursing dams to increase the systemic CORT level of their pups. Here, we observed a reduced number of Hsd11b1-positive cells in the neocortex of these pups. Our observation suggests that Hsd11b1 expression in the developing neocortex is affected by systemic CORT levels. It is possible that stress on mothers influences the neocortical development of their children.

Exposure to pollutants altered glucocorticoid signaling and clock gene expression in female mice. Evidence of tissue- and sex-specificity

Environmental pollutants suspected of disrupting the endocrine system are considered etiologic factors in the epidemic of metabolic disorders. As regulation of energy metabolism relies on the integrated action of a large number of hormones, we hypothesized that certain chemicals could trigger changes in glucocorticoid signaling. To this end, we exposed C57Bl6/J female and male mice between 5 and 20 weeks of age to a mixture of 2,3,7,8- tetrachlorodibenzo-p-dioxin (20 pg/kg body weight/day [bw/d]), polychlorobiphenyl 153 (200 ng/kg bw/d), di-[2-ethylhexyl]-phthalate (500 μg/kg bw/d) and bisphenol A (40 μg/kg bw/d). In female mice fed a standard diet (ST), we observed a decrease in plasma levels of leptin as well as a reduced expression of corticoid receptors Nr3c1 and Nr3c2, of leptin and of various canonical genes related to the circadian clock machinery in visceral (VAT) but not subcutaneous (SAT) adipose tissue. However, Nr3c1 and Nr3c2 mRNA levels did not change in high-fat-fed females exposed to pollutants. In ST-fed males, pollutants caused the same decrease of Nr3c1 mRNA levels in VAT observed in ST-fed females but levels of Nr3c2 and other clock-related genes found to be down-regulated in female VAT were enhanced in male SAT and not affected in male VAT. The expression of corticoid receptors was not affected in the livers of both sexes in response to pollutants. In summary, exposure to a mixture of pollutants at doses lower than the no-observed adverse effect levels (NoAELs) resulted in sex-dependent glucocorticoid signaling disturbances and clock-related gene expression modifications in the adipose tissue of ST-fed mice.

Glucocorticoids affect male testicular steroidogenesis

Through their receptors at each level of hypothalamo-pituitary-gonadal axis glucocorticoid excess, either endogenous or administered or stress-induced, could affect steroid production in the testis and thus male fertility. The main ways by which glucocorticoids act are as follows: 1) Affecting gonadoliberin and LH synthesis and release through glucocorticoid receptors in hypothalamic neurons and pituitary gonadotropes. 2) By so far not clearly evidenced reduction of the number of LH receptors on the membrane of Leydig cells. 3) By affecting expression and function of steroidogenic enzymes in the testis. 4) By regulation of in situ access of glucocorticoid to its target cells in the testis. 5) By promotion Leydig cell apoptosis. The review provides a survey of physiological and molecular mechanisms staying behind these effects. It does not deal with the clinical effects of glucocorticoid treatment which would substantially exceed the scope of the pater.

The detrimental effects of stress-induced glucocorticoid exposure on mouse uterine receptivity and decidualization

Glucocorticoids (GCs), stress-induced steroid hormones, are released by adrenal cortex and essential for stress adaptation. Recently, there has been renewed interest in the relationship between GCs and pregnancy following the discovery that glucocorticoid receptor is necessary for implantation. It has been widely recognized that stress is detrimental to pregnancy. However, effects of stress-induced GC exposure on uterine receptivity and decidualization are still poorly understood. This study aims to explore the effects of GCs exposure on uterine receptivity, decidualization, and their underlying mechanisms in mice. Single prolonged stress (SPS) and corticosterone (Cort) injection models were used to analyze effects of GC exposure on early pregnancy, respectively. SPS or Cort injection inhibits embryo implantation by interfering Lif signaling and stimulating the uterine deposition of collagen types I, III, and IV on day 4 of pregnancy. Uterine decidualization is also attenuated by SPS or Cort injection through suppressing Cox-2 expression. Cort-induced collagen disorder also suppresses decidualization through regulating mesenchymal-epithelial transition. Our data should shed lights for a better understanding for the effects of GCs on embryo implantation for clinical research.

The cross talk of adrenal and Leydig cell steroids in Leydig cells

Glucocorticoid is secreted by adrenal cortex, which binds to intracellular glucocorticoid and mineralocorticoid receptors to regulate steroidogenesis-related gene expression and testosterone production in Leydig cells. Glucocorticoid receptor activity shows inhibitory action on Leydig cell steroidogenesis, while mineralocorticoid receptor activity shows the stimulatory action. Leydig cells contain two important glucocorticoid-metabolizing enzymes, 11β-hydroxysteroid dehydrogenase type 1 and type 2, regulating the intracellular levels of glucocorticoids by a pre-receptor mechanism. 11β-Hydroxysteroid dehydrogenase type 1 is a bidirectional enzyme, and its direction is regulated by intracellular NADP⁺/NADPH redox potential. Leydig cells contain many steroidogenic enzymes, possibly regulating NADP⁺/NADPH redox potential by coupling with 11β-hydroxysteroid dehydrogenase type 1. Here, we review the 11β-hydroxysteroid dehydrogenase regulation and possible consequences in Leydig cell biology and pathology.

Dehydroepiandrosterone Antagonizes Pain Stress-Induced Suppression of Testosterone Production in Male Rats

Background: Leydig cells secrete the steroid hormone, testosterone, which is essential for male fertility and reproductive health. Stress increases the secretion of glucocorticoid [corticosterone, (CORT) in rats] that decreases circulating testosterone levels in part through a direct action on its receptors in Leydig cells. Intratesticular CORT level is dependent on oxidative inactivation of CORT by 11β-hydroxysteroid dehydrogenase 1 (HSD11B1) in rat Leydig cells. Pain may cause the stress, thus affecting testosterone production in Leydig cells.

Methods: Adult male Sprague–Dawley rats orally received vehicle control or 5 or 10 mg/kg dehydroepiandrosterone (DHEA) 0.5 h before being subjected to pain stimulation for 1, 3, and 6 h. In the present study, we investigated the time-course changes of steroidogenic gene expression levels after acute pain-induced stress in rats and the possible mechanism of DHEA that prevented it. Plasma CORT, luteinizing hormone (LH), and testosterone (T) levels were measured, and Leydig cell gene expression levels were determined. The direct regulation of HSD11B1 catalytic direction by DHEA was detected in purified rat Leydig, liver, and rat Hsd11b1-transfected COS1 cells.

Results: Plasma CORT levels were significantly increased at hour 1, 3, and 6 during the pain stimulation, while plasma T levels were significantly decreased starting at hour 3 and 6. Pain-induced stress also decreased Star, Hsd3b1, and Cyp17a1 expression levels at hour 3. When 5 and 10 mg/kg DHEA were orally administered to rats 0.5 h before starting pain stimulation, DHEA prevented pain-mediated decrease in plasma T levels and the expression of Star, Hsd3b1, and Cyp17a1 without affecting plasma CORT levels. DHEA was found to modulate HSD11B1 activities by increasing its oxidative activity and decreasing its reductive activity, thus decreasing the intracellular CORT levels in Leydig cells.

Conclusion: Stress induced by acute pain can inhibit Leydig cell T production by upregulation of corticosterone. DHEA can prevent the negative effects of excessive corticosterone by modulating HSD11B1 activity.

Growth and Stress Axis Responses to Dietary Cholesterol in Nile Tilapia (Oreochromis niloticus) in Brackish Water

Six isonitrogenous and isocaloric diets were formulated to contain 0% (control), 0.4, 0.8, 1.2, 1.6, or 2.4% dietary cholesterol and fed to juvenile Nile tilapia (Oreochromis niloticus) (2.20 ± 0.12 g) twice daily to apparent satiation for 8 weeks in triplicate at a salinity of 16. Fish fed 0.4% cholesterol showed a higher weight gain and specific growth rate and a lower feed coefficient ratio than fish fed other diets. No difference was found in the survival of Nile tilapia fed various levels of cholesterol. Cholesterol in the serum and liver and low-density lipoprotein cholesterol in the serum increased with the increase in the dietary cholesterol content. Relative to the control, no significant difference was found in the expression of head kidney P450scc mRNA between treatment groups. The expression of head kidney 11β-HSD2 mRNA was the highest in the control group, and it decreased significantly with increasing levels of diet cholesterol. Fish fed 0.4 or 1.2% cholesterol had a higher 20β-HSD2 mRNA expression in the head kidney than those fed other diets. Fish fed 0.8% cholesterol had higher expressions of GR1 and GR2B mRNA in the liver than other groups. Fish fed 0.4% cholesterol had the highest activity of gill Na⁺/K⁺-ATPase. Fish fed 0.8 to 2.4% cholesterol had higher serum cortisol contents than the fish in the control group and the fish fed 0.4% cholesterol. This study suggests that dietary cholesterol is not essential for Nile tilapia survival in brackish water, but 0.4% cholesterol supplementation in the Nile tilapia diet contributes to the improvement of hyperosmotic adaptation and increases in gill Na⁺/K⁺-ATPase activity and serum cortisol content by regulating the hypothalamic-pituitary-interrenal stress axis.

Energetic stress: The reciprocal relationship between energy availability and the stress response

The worldwide epidemic of metabolic syndromes and the recognized burden of mental health disorders have driven increased research into the relationship between the two. A maladaptive stress response is implicated in both mental health disorders and metabolic disorders, implicating the hypothalamic-pituitary-adrenal (HPA) axis as a key mediator of this relationship. This review explores how an altered energetic state, such as hyper- or hypoglycemia, as may be manifested in obesity or diabetes, affects the stress response and the HPA axis in particular. We propose that changes in energetic state or energetic demands can result in "energetic stress" that can, if prolonged, lead to a dysfunctional stress response. In this review, we summarize the role of the hypothalamus in modulating energy homeostasis and then briefly discuss the relationship between metabolism and stress-induced activation of the HPA axis. Next, we examine seven mechanisms whereby energetic stress interacts with neuroendocrine stress response systems, including by glucocorticoid signaling both within and beyond the HPA axis; by nutrient-induced changes in glucocorticoid signaling; by impacting the sympathetic nervous system; through changes in other neuroendocrine factors; by inducing inflammatory changes; and by altering the gut-brain axis. Recognizing these effects of energetic stress can drive novel therapies and prevention strategies for mental health disorders, including dietary intervention, probiotics, and even fecal transplant.

Local Glucocorticoid Activation by 11β-Hydroxysteroid Dehydrogenase 1 in Keratinocytes: The Role in Hapten-Induced Dermatitis

Over the past decade, extra-adrenal cortisol production was reported in various tissues. The enzyme that catalyzes the conversion of hormonally inactive cortisone into active cortisol in cells is 11β-hydroxysteroid dehydrogenase 1 (11β-HSD1). We recently reported that 11β-HSD1 is also expressed in keratinocytes and regulates inflammation and keratinocyte proliferation. To investigate the function of 11β-HSD1 in keratinocytes during inflammation in vivo, we created keratinocyte-specific 11β-HSD1 knockout (K5-Hsd11b1-KO) mice and analyzed the inflammatory response in models of hapten-induced contact irritant dermatitis. K5-Hsd11b1-KO mice showed enhanced ear swelling in low-dose oxazolone-, 2,4,6-trinitro-1-chlorobenzene (TNCB)-, and 2,4-dinitrofluorobenzene-induced irritant dermatitis associated with increased inflammatory cell infiltration. Topical application of corticosterone dose dependently suppressed TNCB-induced ear swelling and cytokine expression. Similarly in mouse keratinocytes in vitro, corticosterone dose dependently suppressed 2,4,6-trinitrobenzenesulfonic acid-induced IL-1α and IL-1β expression. The effect of 11-dehydrocorticosterone was attenuated in TNCB-induced irritant dermatitis in K5-Hsd11b1-KO mice compared with wild-type mice. In human samples, 11β-HSD1 expression was decreased in epidermis of psoriasis vulgaris compared with healthy skin. Taken together, these data suggest that corticosterone activation by 11β-HSD1 in keratinocytes suppresses hapten-induced irritant dermatitis through suppression of expression of cytokines, such as IL-1α and IL-1β, in keratinocytes.

Glucocorticoid receptor polymorphisms and haplotypes and their expression in health and disease

Cortisol is involved in many physiological processes, including immunosuppressive and anti-inflammatory actions, and therefore cortisol and its synthetic analogs are widely used to treat a large number of diseases. In glucocorticoid treatment, a large variability of clinical responses is observed. This variability may, in part, be ascribed to genetic variation in the glucocorticoid receptor (GR) gene. In this review we present a catalogue of the various single nucleotide polymorphisms (SNPs) in the glucocorticoid receptor gene and their consequences for human health and disease. Many different GR SNP association studies have been described. However, most studies come down to only a few SNPs reported with different annotations. In this review we clarified these different annotations to uniform names. Most associations between GR SNPs and phenotype have been found in body composition, metabolism, the cardiovascular system, the immune system and psychiatric illnesses. However, many associations have not been replicated (yet), and future replication studies and meta-analyses are needed. There is a substantial body of evidence for GR SNPs to have effects on clinical phenotype. However, as most SNP frequencies are low and their variation is within the range of the general population, the impact of a single SNP for health and disease in the general population is probably modest. However, in-depth studying of the molecular mechanisms of repeatedly observed clinical associations could lead to new possibilities for drug development. In particular the development of selective glucocorticoid receptor modulators holds promise.

11β-hydroxysteroid dehydrogenase 1 specific inhibitor increased dermal collagen content and promotes fibroblast proliferation

Glucocorticoids (GCs) are one of the most effective anti-inflammatory drugs for treating acute and chronic inflammatory diseases. However, several studies have shown that GCs alter collagen metabolism in the skin and induce skin atrophy. Cortisol is the endogenous GC that is released in response to various stressors. Over the last decade, extraadrenal cortisol production in various tissues has been reported. Skin also synthesizes cortisol through a de novo pathway and through an activating enzyme. 11β-hydroxysteroid dehydrogenase 1 (11β-HSD1) is the enzyme that catalyzes the conversion of hormonally inactive cortisone to active cortisol in cells. We previously found that 11β-HSD1 negatively regulates proliferation of keratinocytes. To determine the function of 11β-HSD1 in dermal fibroblasts and collagen metabolism, the effect of a selective 11β-HSD1 inhibitor was studied in mouse tissues and dermal fibroblasts. The expression of 11β-HSD1 increased with age in mouse skin. Subcutaneous injection of a selective 11β-HSD1 inhibitor increased dermal thickness and collagen content in the mouse skin. In vitro, proliferation of dermal fibroblasts derived from 11β-HSD1 null mice (Hsd11b1^−/− mice) was significantly increased compared with fibroblasts from wild-type mice. However, in vivo, dermal thickness of Hsd11b1^−/− mice was not altered in 3-month-old and 1-year-old mouse skin compared with wild-type mouse skin. These in vivo findings suggest the presence of compensatory mechanisms in Hsd11b1^−/− mice. Our findings suggest that 11β-HSD1 inhibition may reverse the decreased collagen content observed in intrinsically and extrinsically aged skin and in skin atrophy that is induced by GC treatment.

Expression profiles of cortisol-inactivating enzyme, 11β-hydroxysteroid dehydrogenase-2, in human epidermal tumors and its role in keratinocyte proliferation

The enzyme 11β-hydroxysteroid dehydrogenase (11β-HSD) catalyzes the interconversion between hormonally active cortisol and inactive cortisone within cells. There are two isozymes: 11β-HSD1 activates cortisol from cortisone and 11β-HSD2 inactivates cortisol to cortisone. 11β-HSD1 was recently discovered in skin, and we subsequently found that the enzyme negatively regulates keratinocyte proliferation. We verified 11β-HSD1 and 11β-HSD2 expression in benign and malignant skin tumors and investigated the role of 11β-HSD in skin tumor pathogenesis. Randomly selected formalin-fixed sections of skin lesions of seborrheic keratosis (SK), squamous cell carcinoma (SCC), and basal cell carcinoma (BCC) were stained with 11β-HSD1 and 11β-HSD2 antibodies, and 11β-HSD expression was also evaluated in murine epidermis in which hyperproliferation was induced by 12-O-tetradecanoylphorbol-13 acetate (TPA). We observed that 11β-HSD1 expression was decreased in all SK, SCC, and BCC lesions compared with unaffected skin. Conversely, 11β-HSD2 expression was increased in SK and BCC but not in SCC. Overexpression of 11β-HSD2 in keratinocytes increased cell proliferation. In the murine model, 11β-HSD1 expression was decreased in TPA-treated hyperproliferative skin. Our findings suggest that 11β-HSD1 expression is decreased in keratinocyte proliferative conditions, and 11β-HSD2 expression is increased in basal cell proliferating conditions, such as BCC and SK. Assessing 11β-HSD1 and 11β-HSD2 expression could be a useful tool for diagnosing and characterizing skin tumors.

A pharmacological screening approach for discovery of neuroprotective compounds in ischemic stroke

With the availability and ease of small molecule production and design continuing to improve, robust, high-throughput methods for screening are increasingly necessary to find pharmacologically relevant compounds amongst the masses of potential candidates. Here, we demonstrate that a primary oxygen glucose deprivation assay in primary cortical neurons followed by secondary assays (i.e. post-treatment protocol in organotypic hippocampal slice cultures and cortical neurons) can be used as a robust screen to identify neuroprotective compounds with potential therapeutic efficacy. In our screen about 50% of the compounds in a library of pharmacologically active compounds displayed some degree of neuroprotective activity if tested in a pre-treatment toxicity assay but just a few of these compounds, including Carbenoxolone, remained active when tested in a post-treatment protocol. When further examined, Carbenoxolone also led to a significant reduction in infarction size and neuronal damage in the ischemic penumbra when administered six hours post middle cerebral artery occlusion in rats. Pharmacological testing of Carbenoxolone-related compounds, acting by inhibition of 11-β-hydroxysteroid dehydrogenase-1 (11β-HSD1), gave rise to similarly potent in vivo neuroprotection. This indicates that the increase of intracellular glucocorticoid levels mediated by 11β-HSD1 may be involved in the mechanism that exacerbates ischemic neuronal cell death, and inhibiting this enzyme could have potential therapeutic value for neuroprotective therapies in ischemic stroke and other neurodegenerative disorders associated with neuronal injury.

Association of 11β-hydroxysteroid dehydrogenase type 1 gene polymorphisms with serum alanine aminotransferase activity

AIMS

11β-Hydroxysteroid dehydrogenase type 1 (HSD11B1), which converts inactive glucocorticoid to active glucocorticoid, plays a critical role in pathogenesis of non-alcoholic fatty liver disease (NAFLD). Serum alanine aminotransferase (ALT), an indicator of hepatocellular injury, has been suggested as a surrogate marker for NAFLD. To date, no study has specifically examined the relationship between HSD11B1 gene polymorphisms and ALT.

METHODS

A study was conducted to examine the association of common single nucleotide polymorphisms (SNPs) in HSD11B1 (rs12086634, rs1000283) with serum ALT level in 756 Korean subjects (348 males and 408 females). ALT values were divided into two groups: elevated (>33U/l in males, >25U/l in females) and normal.

RESULTS

SNPs showed a significant association with elevated ALT. According to results of logistic regression analysis adjusted for confounding variables, the GT+GG genotype for rs12086634 and the GA+AA genotype for rs1000283 showed significantly higher frequencies of elevated ALT, compared with the TT and GG genotypes, respectively (GT/GG vs. TT; OR 1.685, 95% CI 1.175-2.416, P=0.005, GA/AA vs. GG; OR 2.057, 95% CI 1.401-3.020, P<0.001, respectively).

CONCLUSIONS

HSD11B1 polymorphisms (rs12086634 and rs1000283) are associated with elevated levels of ALT. Findings from this study suggest a possible association between HSD11B1 polymorphisms and hepatocellular injury, such as that seen in patients with NAFLD.

Adamantyl carboxamides and acetamides as potent human 11β-hydroxysteroid dehydrogenase type 1 inhibitors

The modulation of 11β-HSD1 activity with selective inhibitors has beneficial effects on various metabolic disorders including insulin resistance, dyslipidemia and obesity. Here we report the discovery of a series of novel adamantyl carboxamide and acetamide derivatives as selective inhibitors of human 11β-HSD1 in HEK-293 cells transfected with the HSD11B1 gene. Optimization based on an initially identified 11β-HSD1 inhibitor (3) led to the discovery of potent inhibitors with IC(50) values in the 100 nM range. These compounds are also highly selective 11β-HSD1 inhibitors with no activity against 11β-HSD2 and 17β-HSD1. Compound 15 (IC(50)=114 nM) with weak inhibitory activity against the key human cytochrome P450 enzymes and moderate stability in incubation with human liver microsomes is worthy of further development. Importantly, compound 41 (IC(50)=280 nM) provides a new lead that incorporates an adamantyl group surrogate and should enable further series diversification.

The hypothalamic-pituitary-adrenal axis and sex hormones in chronic stress and obesity: pathophysiological and clinical aspects

Obesity, particularly the abdominal phenotype, has been ascribed to an individual maladaptation to chronic environmental stress exposure mediated by a dysregulation of related neuroendocrine axes. Alterations in the control and action of the hypothalamic-pituitary-adrenal axis play a major role in this context, with the participation of the sympathetic nervous system. The ability to adapt to chronic stress may differ according to sex, with specific pathophysiological events leading to the development of stress-related chronic diseases. This seems to be influenced by the regulatory effects of sex hormones, particularly androgens. Stress may also disrupt the control of feeding, with some differences according to sex. Finally, the amount of experimental data in both animals and humans may help to shed more light on specific phenotypes of obesity, strictly related to the chronic exposure to stress. This challenge may potentially imply a different pathophysiological perspective and, possibly, a specific treatment.

The skin-blanching assay

The skin-blanching assay is used for the determination and bioequivalence of dermatologic glucocorticoids (GCs). The exact mechanism of the production of blanching is not fully understood, but it is considered that local vasoconstriction of the skin microvasculature and the consequent blood-flow reduction cause this phenomenon. Several factors influence skin blanching, including drug concentration, duration of application, nature of vehicle, occlusion, posture and location. The intensity of vasoconstriction can be measured in several ways: visual or quantitative methods, such as reflectance spectroscopy, thermography, laser Doppler velocimetry and chromametry. In literature, contradicting results in the correlation of the skin-blanching assay with different tests to determine GC sensitivity have been reported, limiting its clinical usefulness.

11β-Hydroxysteroid dehydrogenase-1 is a novel regulator of skin homeostasis and a candidate target for promoting tissue repair

11β-hydroxysteroid dehydrogenase 1 (11β-HSD1) catalyzes the interconversion of cortisone and cortisol within the endoplasmic reticulum. 11β-HSD1 is expressed widely, most notably in the liver, adipose tissue, and central nervous system. It has been studied intensely over the last 10 years because its activity is reported to be increased in visceral adipose tissue of obese people. Epidermal keratinocytes and dermal fibroblasts also express 11β-HSD1. However, the function of the enzymatic activity 11β-HSD1 in skin is not known. We found that 11β-HSD1 was expressed in human and murine epidermis, and this expression increased as keratinocytes differentiate. The expression of 11β-HSD1 by normal human epidermal keratinocytes (NHEKs) was increased by starvation or calcium-induced differentiation in vitro. A selective inhibitor of 11β-HSD1 promoted proliferation of NHEKs and normal human dermal fibroblasts, but did not alter the differentiation of NHEKs. Topical application of selective 11β-HSD1 inhibitor to the dorsal skin of hairless mice caused proliferation of keratinocytes. Taken together, these data suggest that 11β-HSD1 is involved in tissue remodeling of the skin. This hypothesis was further supported by the observation that topical application of the selective 11β-HSD1 inhibitor enhanced cutaneous wound healing in C57BL/6 mice and ob/ob mice. Collectively, we conclude that 11β-HSD1 is negatively regulating the proliferation of keratinocytes and fibroblasts, and cutaneous wound healing. Hence, 11β-HSD1 might maintain skin homeostasis by regulating the proliferation of keratinocytes and dermal fibroblasts. Thus 11β-HSD1 is a novel candidate target for the design of skin disease treatments.

Adamantyl ethanone pyridyl derivatives: potent and selective inhibitors of human 11β-hydroxysteroid dehydrogenase type 1

Elevated levels of active glucocorticoids have been implicated in the development of several phenotypes of metabolic syndrome, such as type 2 diabetes and obesity. 11β-Hydroxysteroid dehydrogenase type 1 (11β-HSD1) catalyses the intracellular conversion of inactive cortisone to cortisol. Selective 11β-HSD1 inhibitors have shown beneficial effects in various conditions, including diabetes, dyslipidemia and obesity. A series of adamantyl ethanone pyridyl derivatives has been identified, providing potent and selective inhibitors of human 11β-HSD1. Lead compounds display low nanomolar inhibition against human and mouse 11β-HSD1 and are selective for this isoform, with no activity against 11β-HSD2 and 17β-HSD1. Structure-activity relationship studies reveal that an unsubstituted pyridine tethered to an adamantyl ethanone motif through an ether or sulfoxide linker provides a suitable pharmacophore for activity. The most potent inhibitors have IC₅₀ values around 34-48 nM against human 11β-HSD1, display reasonable metabolic stability in human liver microsomes, and weak inhibition of key human CYP450 enzymes.

Discovery of adamantyl heterocyclic ketones as potent 11β-hydroxysteroid dehydrogenase type 1 inhibitors

11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) plays a key role in converting intracellular cortisone to physiologically active cortisol, which is implicated in the development of several phenotypes of metabolic syndrome. Inhibition of 11β-HSD1 activity with selective inhibitors has beneficial effects on various conditions, including diabetes, dyslipidemia and obesity, and therefore constitutes a promising strategy to discover novel therapies for metabolic and cardiovascular diseases. A series of novel adamantyl heterocyclic ketones provides potent and selective inhibitors of human 11β-HSD1. Lead compounds display low nanomolar inhibition against human and mouse 11β-HSD1 and are selective with no activity against 11β-HSD2 and 17β-HSD1. Selected potent 11β-HSD1 inhibitors show moderate metabolic stability upon incubation with human liver microsomes and weak inhibition of human CYP450 enzymes.

Relationship of 11β-hydroxysteroid dehydrogenase type 1 and hexose-6-phosphate dehydrogenase gene polymorphisms with metabolic syndrome and type 2 diabetes

11β-Hydroxysteroid dehydrogenase type 1 (HSD11B1), which converts inactive glucocorticoid to active glucocorticoid, plays a critical role in the pathogenesis of visceral obesity, metabolic syndrome, and diabetes. Hexose-6-phosphate dehydrogenase (H6PD) supplies a crucial cofactor, reduced nicotinamide adenine dinucleotide phosphate (NADPH), which allows HSD11B1 to maintain reductase activity. The association of common SNPs in HSD11B1 [IVS3-29G/T (rs12086634), IVS4-11120A/G (rs1000283)] and H6PD [R453Q (rs6688832), P554L (rs17368528)], either separately or combined, with type 2 diabetes and metabolic syndrome was examined in 427 Korean subjects with type 2 diabetes and in 358 nondiabetic Korean subjects. HSD11B1 polymorphisms (rs12086634 and rs1000283) were associated with metabolic syndrome among type 2 diabetic subjects and an H6PD polymorphism (rs17368528) was a risk factor for metabolic syndrome in nondiabetic subjects. However, no significant association of these SNPs with type 2 diabetes and metabolic syndrome was found after considering the multiple comparisons in the total study population. In conclusion, HSD11B1 and H6PD polymorphisms may not be associated with type 2 diabetes and metabolic syndrome. Further investigation of the role of these gene polymorphisms on the pathogenesis of metabolic syndrome is required.

Serum dehydroepiandrosterone sulphate levels in patients with non-alcoholic fatty liver disease

BACKGROUND

Dehydroepiandrosterone (DHEA) is an adrenal hormone reported to prevent body weight gain, diabetes mellitus and atherosclerosis. We hypothesized that DHEA is involved in the pathophysiology of non-alcoholic fatty liver disease (NAFLD) often associated with obesity and insulin resistance. In this study, we aimed to examine the clinical significance of serum DHEA sulfate (DHEAS) in patients with NAFLD.

METHODS

We determined serum DHEAS, serum alanine aminotransferase (ALT), serum lipids, plasma fasting glucose and insulin levels in 158 Japanese men who had neither viral hepatic diseases nor alcohol intake exceeding 20 g/day. NAFLD was diagnosed by the presence of fatty change of the liver by echotomographic examination.

RESULTS

Among the study subjects, 69 were diagnosed as having NAFLD. Their serum DHEAS levels were significantly higher than in 89 subjects without NAFLD. Serum DHEAS levels in 19 NAFLD patients with elevated ALT levels (>40 U/L) were significantly higher than in the other 50 NAFLD patients with normal ALT levels (≤40 U/L). Multivariate regression analysis demonstrated that serum ALT was positively correlated with serum DHEAS, serum triglyceride and body mass index.

CONCLUSION

Serum DHEAS levels are increased in patients with NAFLD with elevated ALT levels. Increased serum DHEAS may be a component of the pathophysiology of NAFLD.

Discovery of adamantyl ethanone derivatives as potent 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) inhibitors

11Beta-hydroxysteroid dehydrogenases (11beta-HSDs) are key enzymes regulating the pre-receptor metabolism of glucocorticoid hormones. The modulation of 11beta-HSD type 1 activity with selective inhibitors has beneficial effects on various conditions including insulin resistance, dyslipidemia and obesity. Inhibition of tissue-specific glucocorticoid action by regulating 11beta-HSD1 constitutes a promising treatment for metabolic and cardiovascular diseases. A series of novel adamantyl ethanone compounds was identified as potent inhibitors of human 11beta-HSD1. The most active compounds identified (52, 62, 72, 92, 103 and 104) display potent inhibition of 11beta-HSD1 with IC(50) values in the 50-70 nM range. Compound 72 also proved to be metabolically stable when incubated with human liver microsomes. Furthermore, compound 72 showed very weak inhibitory activity for human cytochrome P450 enzymes and is therefore a candidate for in vivo studies. Comparison of the publicly available X-ray crystal structures of human 11beta-HSD1 led to docking studies of the potent compounds, revealing how these molecules may interact with the enzyme and cofactor.

Transcriptome profiling and network analysis of genetically hypertensive mice identifies potential pharmacological targets of hypertension

Hypertension is a condition with major cardiovascular and renal complications, affecting nearly a billion patients worldwide. Few validated gene targets are available for pharmacological intervention, so there is a need to identify new biological pathways regulating blood pressure and containing novel targets for treatment. The genetically hypertensive “blood pressure high” (BPH), normotensive “blood pressure normal” (BPN), and hypotensive “blood pressure low” (BPL) inbred mouse strains are an ideal system to study differences in gene expression patterns that may represent such biological pathways. We profiled gene expression in liver, heart, kidney, and aorta from BPH, BPN, and BPL mice and determined which biological processes are enriched in observed organ-specific signatures. As a result, we identified multiple biological pathways linked to blood pressure phenotype that could serve as a source of candidate genes causal for hypertension. To distinguish in the kidney signature genes whose differential expression pattern may cause changes in blood pressure from those genes whose differential expression pattern results from changes in blood pressure, we integrated phenotype-associated genes into Genetic Bayesian networks. The integration of data from gene expression profiling and genetics networks is a valuable approach to identify novel potential targets for the pharmacological treatment of hypertension.

From estrogen-centric to aging and oxidative stress: a revised perspective of the pathogenesis of osteoporosis

Estrogen deficiency has been considered the seminal mechanism of osteoporosis in both women and men, but epidemiological evidence in humans and recent mechanistic studies in rodents indicate that aging and the associated increase in reactive oxygen species (ROS) are the proximal culprits. ROS greatly influence the generation and survival of osteoclasts, osteoblasts, and osteocytes. Moreover, oxidative defense by the FoxO transcription factors is indispensable for skeletal homeostasis at any age. Loss of estrogens or androgens decreases defense against oxidative stress in bone, and this accounts for the increased bone resorption associated with the acute loss of these hormones. ROS-activated FoxOs in early mesenchymal progenitors also divert ss-catenin away from Wnt signaling, leading to decreased osteoblastogenesis. This latter mechanism may be implicated in the pathogenesis of type 1 and 2 diabetes and ROS-mediated adverse effects of diabetes on bone formation. Attenuation of Wnt signaling by the activation of peroxisome proliferator-activated receptor gamma by ligands generated from lipid oxidation also contributes to the age-dependent decrease in bone formation, suggesting a mechanistic explanation for the link between atherosclerosis and osteoporosis. Additionally, increased glucocorticoid production and sensitivity with advancing age decrease skeletal hydration and thereby increase skeletal fragility by attenuating the volume of the bone vasculature and interstitial fluid. This emerging evidence provides a paradigm shift from the "estrogen-centric" account of the pathogenesis of involutional osteoporosis to one in which age-related mechanisms intrinsic to bone and oxidative stress are protagonists and age-related changes in other organs and tissues, such as ovaries, accentuate them.

Effect of 11 beta-hydroxysteroid dehydrogenase-1 inhibition on hepatic glucose metabolism in the conscious dog

Inactive cortisone is converted to active cortisol within the liver by 11 beta-hydroxysteroid dehydrogenase-1 (11 beta-HSD1), and impaired regulation of this process may be related to increased hepatic glucose production (HGP) in individuals with type 2 diabetes. The primary aim of this study was to investigate the effect of acute 11 beta-HSD1 inhibition on HGP and fat metabolism during insulin deficiency. Sixteen conscious, 42-h-fasted, lean, healthy dogs were studied. Somatostatin was infused to create insulin deficiency, and the animals were treated with a specific 11 beta-HSD1 inhibitor (compound 531) or placebo for 5 h. 11 beta-HSD1 inhibition completely suppressed hepatic cortisol production, and this attenuated the increase in HGP that occurred during insulin deficiency. PEPCK and glucose-6-phosphatase expression were decreased when 11 beta-HSD1 was inhibited, but gluconeogenic flux was unchanged, implying an effect on glycogenolysis. Since inhibition of hepatic cortisol production reduces HGP during insulin deficiency, 11 beta-HSD1 is a potential therapeutic target for the treatment of excess glucose production that occurs in diabetes.

Endogenous glucocorticoids decrease skeletal angiogenesis, vascularity, hydration, and strength in aged mice

Aging or glucocorticoid excess decrease bone strength more than bone mass in humans and mice, but an explanation for this mismatch remains elusive. We report that aging in C57BL/6 mice was associated with an increase in adrenal production of glucocorticoids as well as bone expression of 11beta-hydroxysteroid dehydrogenase (11beta-HSD) type 1, the enzyme that activates glucocorticoids. Aging also decreased the volume of the bone vasculature and solute transport from the peripheral circulation to the lacunar-canalicular system. The same changes were reproduced by pharmacologic hyperglucocorticoidism. Furthermore, mice in which osteoblasts and osteocytes were shielded from glucocorticoids via cell-specific transgenic expression of 11beta-HSD type 2, the enzyme that inactivates glucocorticoids, were protected from the adverse effects of aging on osteoblast and osteocyte apoptosis, bone formation rate and microarchitecture, crystallinity, vasculature volume, interstitial fluid, and strength. In addition, glucocorticoids suppressed angiogenesis in fetal metatarsals and hypoxia inducible factor-1alpha transcription and vascular endothelial growth factor production in osteoblasts and osteocytes. These results, together with the evidence that dehydration of bone decreases strength, reveal that endogenous glucocorticoids increase skeletal fragility in old age as a result of cell autonomous effects on osteoblasts and osteocytes leading to interconnected decrements in bone angiogenesis, vasculature volume, and osteocyte-lacunar-canalicular fluid.

11beta-hydroxysteroid dehydrogenase activity in acromegalic patients with normal or impaired carbohydrate metabolism

The 11beta-hydroxysteroid dehydrogenase isoenzymes (11beta-HSD) catalyse the interconversion of cortisol (F) and cortisone (E). Earlier studies demonstrated that growth hormone (GH) and insulin resistance may exert opposite effects on the conversion of E to F by 11beta-HSD type 1. Therefore, in the present study we determined F and E concentrations in 562 plasma samples obtained from acromegalic patients during an active phase (76 patients) and after cure of the disease (68 patients). In addition, we examined whether type 2 diabetes mellitus or impaired glucose tolerance, which are frequently associated with active acromegaly could influence plasma F and E levels in these patients. We found that plasma F concentrations were similar in patients with active acromegaly and in those who were cured with pituitary surgery, irradiation and/or medical therapy (mean+/-S.E., 12.4+/-0.3 and 12.7+/-0.4 microg/dl, respectively). However, plasma E levels were significantly higher in patients with active compared to those with cured acromegaly (2.8+/-0.1 and 2.2+/-0.1 microg/dl, respectively; p<0.001), resulting in a lower F/E ratio in patients with active disease (4.6+/-0.1 vs. 5.9+/-0.2 in the cured group of patients; p<0.001). When the effect of altered carbohydrate homeostasis on plasma F and E was analysed, the results indicated significantly lower plasma E levels and higher F/E ratios in active acromegalic patients with type 2 diabetes mellitus or impaired glucose tolerance compared to those with normal carbohydrate metabolism (E, 2.5+/-0.1 and 3.0+/-0.1 microg/dl, respectively; F/E, 5.1+/-0.2 and 4.4+/-0.1; p<0.001), whereas plasma F concentrations were similar in these two groups (12.1+/-0.4 and 12.6+/-0.3 microg/dl, respectively). These findings indicate that disease activity exerts a significant impact on 11beta-HSD in acromegalic patients, which is further modified with altered carbohydrate homeostasis, frequently present in patients with active disease.

Sex-dependent role of glucocorticoids and androgens in the pathophysiology of human obesity

Obesity, particularly its abdominal phenotype, a harbinger of the metabolic syndrome, cardiovascular diseases (CVDs) and type 2 diabetes mellitus (T2D), is becoming one of the most significant public health problems worldwide. Among many other potential factors, derangement of multiple hormone systems have increasingly been considered for their potential importance in the pathophysiology of obesity and the metabolic syndrome, with particular reference to glucocorticoids and sex hormones. These systems have a fundamental and coordinating role in the physiology of intermediate metabolism and cardiovascular function, and in the response to acute and chronic stress challenge. Abdominal obesity is associated with a hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis and impaired androgen balance, although these alterations differ according to sex. As there is also increasing evidence that there are many differences between the sexes in the susceptibility and development of obesity, T2D and CVDs, we support the hypothesis that alterations of the HPA axis and androgen balance may have an important function in this context. This is further supported by the fact that there are important differences between males and females in their ability to adapt to both internal and particularly to environmental (external) stressors. In addition, there is also evidence that, in both physiological and pathological conditions, a close cross talk exists between sex hormones and glucocorticoids at both neuroendocrine and peripheral level, again with different specificities according to sex.

Corticosterone oxidative neutralization by 11-beta hydroxysteroid dehydrogenases in kidney and colon of the domestic fowl

In mammalian organs involved in sodium reabsorption, the 11-beta hydroxysteroid dehydrogenases (11betaHSDs) oxidize glucocorticoids (GC) from their 11-alcohol form to their 11-keto state and therefore prevent their binding to mineralocorticoid (MC) receptors (MR) and the development of a MC excess syndrome. In birds the information about 11betaHSDs and GC metabolism in such organs is scarce. Herein, we report the expression and enzymatic activity of 11betaHSDs in the kidney and colon of chickens. Both organs express 11betaHSD2-like mRNA. With NAD(+), microsomes from both tissues oxidized corticosterone (CS) into 11-dehydrocorticosterone (DHC) with K(m) of 200 and 20nM and V(max) of 13 and 2pmol/mg protein/min in the kidney and colon, respectively. Thiram, a specific 11betaHSD2 inhibitor, suppressed this oxidation in kidney. The expression and action of the putative 11betaHSD3 were also tested. The chicken colon, and to a greater extent the kidney, expressed 11betaHSD3-like mRNA. Microsomal fractions from both tissues oxidized CS into DHC in the presence of NADP(+) with K(m) of 150 and 4nM and V(max) of 5 and 0.3pmol/mg protein/min for the kidney and the colon, respectively. This oxidation was not affected when NADP(+) conversion into NAD(+) was inhibited by excess pyrophosphate or a phosphatase inhibitor cocktail. In microsomes of chicken's duodenum, where 11betaHSD1-like mRNA expression is high, NADP(+)-dependent oxidation of CS into DHC has a low-affinity K(m) of 1130nM. This study documented the expression and activity of two enzymes that convert CS into DHC, one is 11betaHSD2-like and the other is similar to the putative mammalian 11betaHSD3.

Glucocorticoid action and the development of selective glucocorticoid receptor ligands

Glucocorticoids are important endocrine regulators of a wide range of physiological systems ranging from respiratory development, immune function to responses to stress. Glucocorticoids in cells activate the cytoplasmic glucocorticoid receptor (GR) that dimerizes, translocates to the nucleus and functions as a ligand-dependent transcriptional regulator. Synthetic glucocorticoids such as dexamethasone and prednisolone have for decades been the cornerstone for the clinical treatment of inflammatory diseases, such as rheumatoid arthritis and asthma, and in some lymphoid cancers, yet its prolonged use has undesirable side effects such as obesity, diabetes, immune suppression and osteoporosis. Detailed knowledge on the mechanism of GR action has led to the development of novel selective glucocorticoid receptor modulators (SGRMs) that show promise of being efficacious for specific treatments of disease but with fewer side effects. SGRMs promote specific recruitment of transcriptional co-regulators that elicit specific gene responses and show promise of greater efficacy and specificity in treatment of inflammatory diseases and type-2 diabetes.

Localization and glucocorticoid regulation of 11β-hydroxysteroid dehydrogenase type 1 mRNA in the male mouse forebrain

The enzyme 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) converts the inactive 11-dehydrocorticosterone into the active glucocorticoid corticosterone. There is accumulating evidence indicating widespread expression of 11beta-HSD1 in the brain. However, there is little information about regulation of 11beta-HSD1 expression in this tissue. Using in situ hybridization involving use of 35S-labeled cRNA probe, we have studied the distribution of cells expressing 11beta-HSD1 mRNA in the male mouse forebrain as well as the effects of adrenalectomy (ADX) and acute administration of corticosterone (3 and 24 h) on 11beta-HSD1 mRNA levels. Cells expressing 11beta-HSD1 mRNA were mostly detected in the cerebral cortex, hippocampus, amygdala and medial preoptic area, with the highest expression in the cerebral cortex (retrosplenial granular area) and hippocampus (CA3 and granular layer of the gyrus dentatus). Seven days following ADX, 11beta-HSD mRNA levels were increased by 50% in the gyrus dentatus, by 100% in the CA3 area, and 105% in the cerebral cortex. Administration of corticosterone to ADX mice induced a significant decrease in mRNA, in both the hippocampus and cerebral cortex so that, at the 24 h time interval, the levels were similar to those observed in intact mice. These results clearly indicate that circulating corticosterone is downregulating the expression of 11beta-HSD1 mRNA in the two forebrain areas studied. This downregulation might contribute to maintain low intracellular corticosterone levels in central regions and then prevent the deleterious effects induced by high glucocorticoid levels.

Glucocorticoid signalling affects pancreatic development through both direct and indirect effects

AIMS/HYPOTHESIS

Beta cell development is sensitive to glucocorticoid levels. Although direct effects of glucocorticoids on pancreatic precursors have been shown to control beta cell mass expansion, indirect effects of these hormones on pancreatic development remain unexplored. This issue was addressed in mice lacking the glucocorticoid receptor (GR) in the whole organism.

MATERIALS AND METHODS

The pancreatic phenotype of GR(null/null) mice was studied at fetal ages (embryonic day [E]) E15.5 and E18 by immunohistochemistry and beta cell fraction measurements. To distinguish between direct and indirect effects, mutant E15.5 fetal pancreata were grafted under the kidney capsule of immunodeficient mice and analysed after 1 week.

RESULTS

E18 GR(null/null) fetuses had smaller digestive tracts and tiny pancreata. Massive pancreatic disorganisation and apoptosis were observed despite the presence of all cell types. E15.5 GR(null/null) mutants were indistinguishable from wild-type regarding pancreatic size, tissue structure and organisation, beta cell fraction and production of exocrine transcription factor Ptf1a, neurogenin 3 and Pdx-1. Grafting E15.5 GR(null/null) pancreata into a GR-expressing environment rescued the increased apoptosis and mature islets were observed, suggesting that GR(null/null) pancreatic cell death can be attributed to indirect effects of glucocorticoids on this tissue. Heterozygous GR(+/null) mutants with reduced GR numbers showed no apoptosis but increased beta cell fraction at E18 and the adult age, strengthening the importance of an accurate GR dosage on beta cell mass expansion.

CONCLUSIONS/INTERPRETATION

Our results provide evidence for GR involvement in pancreatic tissue organisation and survival through indirect effects. GR does not appear necessary for early phases, but its accurate dosage is critical to modulate beta cell mass expansion at later fetal stages, presumably through direct effects.

Intracrine modulation of gene expression by intracellular generation of active glucocorticoids

Glucocorticoids (GC) by either up-regulating or down-regulating the expression of genes influence cellular processes in every tissue and organ of the body. The enzyme 11beta-hydroxysteroid dehydrogenase Type-1 (11beta-HSD-1) confers bioactivity upon the inactive GC cortisone (E) and prednisone (P) by converting them to cortisol (F) and prednisolone (L), respectively. We sought to investigate whether gene expression modulation by GC is under the regulation of an intracrine mechanism that determines the intracellular concentration of active GC. Human cell lines were transiently and stably co-transfected with an expression construct for 11beta-HSD-1 and a GC-responsive reporter gene and incubated with active and inactive GC. Whereas in cells that were not transfected with the expression construct for 11beta-HSD-1 inactive GC had no transcriptional activity, in both transiently and stably transfected cells E and P demonstrated a dose-dependent transcriptional activity. This transcriptional potency of both inactive GC was effectively abolished by carbenoxolone, an 11beta-HSD-1 inhibitor, and was directly related to the concentration of transfected 11beta-HSD-1. We conclude that gene expression modulation by GC is under a decisive influence of target cell 11beta-HSD-1 that modulates the intracellular concentration of active GC. The intracrine mechanism is an under-appreciated aspect of GC activity that could be a potential target for future therapies aimed at modulating GC effects at the cellular level.

The Hypothalamic-Pituitary-Adrenal Axis Activity in Obesity and the Metabolic Syndrome

A hypothetical role of glucocorticoids in human obesity has been suggested since the abdominal obesity phenotype and syndromes of endogenous or exogenous hypercortisolism share several clinical, metabolic, and cardiovascular similarities. An emerging body of evidence indicates that both neuroendocrine dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis as well as peripheral alterations of cortisol metabolism may play a role in the pathophysiology of abdominal obesity. Major alterations of the HPA axis in vivo may be identified in different ways. They include evaluation of hormone concentrations: (a) in basal conditions, in blood, urine, or saliva samples; (b) during dynamic studies following stimulation with different neuropeptides or psychological stress challenges, or suppression with inhibiting agents of the HPA axis at different levels; and (c) after mixed meals or meals containing different nutrient compositions. In addition, alteration of peripheral cortisol metabolism can be detected by direct measurement of cortisol metabolites in urine, although this is a matter of more complex investigation. Alterations of the HPA axis in abdominal obesity are associated with insulin resistance, which suggests a direct responsibility of these hormonal alterations in the susceptibility of affected patients to develop both metabolic and cardiovascular diseases. According to available data, no single marker probably has the power to detect subtle alterations of the HPA axis in conditions, such as the abdominal obesity and the metabolic syndrome. On the contrary, they indicate the need for multiple parameters. At present, evaluation of urinary free cortisol, particularly during the night-time, and salivary-free cortisol appear to be promising for these purposes, whereas dynamic tests should be reserved for specific clinical settings, involving well-characterized patients.

Selective antagonism of the hepatic glucocorticoid receptor reduces hepatic glucose production

A liver-selective glucocorticoid (GC) receptor antagonist (A-348441) was used to determine the effect of reduced hepatic GC signaling on hepatic glucose production. Fasted conscious dogs were studied in the presence (GRA, n = 6) or absence (CON, n = 6) of the intraduodenally administered GC receptor antagonist (100 mg/kg). All dogs were maintained on a pancreatic clamp and in a euglycemic state for 7 hours to ensure that any changes in glucose metabolism were the direct result of the effects of A-348441, which was given at the start of a 5-hour experimental period. In the GRA group, the arterial plasma insulin level was 4.6 +/- 0.7 and 4.8 +/- 0.6 microU/mL during the basal and the last 30 minutes of the experimental periods, respectively. In the CON group, it was 4.0 +/- 0.3 and 4.5 +/- 0.5 microU/mL in the 2 periods, respectively. The arterial plasma glucagon level was 49 +/- 4 and 46 +/- 3 pg/mL in the 2 periods in the GRA group, and 45 +/- 3 and 42 +/- 3 pg/mL in the CON group. Net hepatic glucose balance progressively decreased in the GRA group from 1.31 +/- 0.18 to 0.49 +/- 0.30 mg/kg per minute, whereas in the CON group, net hepatic glucose balance was 1.17 +/- 0.09 and 1.43 +/- 0.18 mg/kg per minute during the basal and last 30 minutes of the experimental periods, respectively. No significant change in net renal or gut glucose balance or nonhepatic glucose uptake was observed in either group. This study demonstrates that the GC receptor plays an important role in the regulation of basal hepatic glucose production and represents a significant potential therapeutic target.

Rapid actions of aldosterone in vascular health and disease—friend or foe?

The mineralocorticoid receptor (MR) and the enzyme 11betahydroxysteroid dehydrogenase type 2, which confers aldosterone specificity to the MR, are present in endothelium and vascular smooth muscle. In several pathological conditions aldosterone promotes vascular damage by formation of reactive oxygen species. The effect of aldosterone on vascular function, however, is far from clear. By rapid non-genomic mechanisms aldosterone may cause calcium mobilization and vasoconstriction, or may stimulate nitric oxide formation through the PI-3 kinase/Akt pathway and thereby counteract vasoconstriction. Vasoconstrictor, vasodilator or no effects of aldosterone have been reported from studies on human forearm blood flow. Inhibition of MR with spironolactone improves endothelial function in patients with heart failure but worsens endothelial function in type 2 diabetic patients. The aim of the present review is to reconcile some of the apparently conflicting data. A key observation is that reactive oxygen and nitrogen species serve as physiological signaling molecules at low concentrations, while they initiate pathological processes at higher concentrations. The net effect of aldosterone, which stimulates ROS production, therefore depends on the ambient level of oxidative stress. Thus, in situations with low levels of oxidative stress aldosterone may promote vasodilatation, while at higher oxidative stress (high NaCl intake, pre-existing vascular pathological conditions, high oxygen tension in vitro) aldosterone is likely to be associated with vasoconstriction and oxidative damage, and in this setting inhibition of the MR is likely to be beneficial.

Obesity and androgens: facts and perspectives

OBJECTIVE

This review discusses androgen status in male and female obesity, according to their specific phenotype, and the main mechanisms responsible.

DESIGN

Published data in the literature of the last 20 years represented the basis of most of the data and concepts incorporated in the review.

RESULT(S)

Obesity is associated with profound alterations in androgen secretion, transport, metabolism, and action, according to a dichotomous behavior depending on sex. Obese men are characterized by a progressive decrease of testosterone levels with increasing body weight, whereas obese women, particularly those with the abdominal phenotype, tend to develop a condition of functional hyperandrogenism. Reduced sex hormone-binding globulin synthesis and circulating blood levels represent the sole common mechanism which is responsible in both sexes. Among other still partially undefined factors, mechanisms potentially responsible for the sex dichotomy in androgen levels involve specific alterations of gonadotropin secretion, estrogens, the hypothalamic-pituitary-adrenal axis, leptin, androgen receptors, specific steroidogenic enzymes in the peripheral tissues, and, possibly, ghrelin. In both sexes, androgens play an important role in determining the sex-dependent pattern of body fat distribution. Moreover there are theoretical possibilities that low testosterone in men and high free testosterone fraction in women may play a role in the development of the metabolic syndrome. This is exemplified by the well defined association between obesity and other features of the metabolic syndrome in women with polycystic ovary syndrome and in hypogonadal men. The effects of androgen and antiandrogens in obese men and women also represent arguments in favor of this association.

CONCLUSION(S)

Given the fundamental role of sex hormones in the regulation of body composition, fuel homeostasis, and reproduction in humans, more emphasis should be placed on the potential role of androgen dysregulation in the pathophysiology of different obesity phenotypes and the metabolic syndrome.