Colitis up-regulates local glucocorticoid activation and down-regulates inactivation in colonic tissue

The Gut Microbiota Affects Corticosterone Production in the Murine Small Intestine

Glucocorticoids (GCs) are hormones that are released in response to stressors and exhibit many activities, including immunomodulatory and anti-inflammatory activities. They are primarily synthesized in the adrenal gland but are also produced in peripheral tissues via regeneration of adrenal 11-oxo metabolites or by de novo synthesis from cholesterol. The present study investigated the influence of the microbiota on de novo steroidogenesis and regeneration of corticosterone in the intestine of germ-free (GF) and specific pathogen-free mice challenged with a physical stressor (anti-CD3 antibody i.p. injection). In the small intestine, acute immune stress resulted in increased mRNA levels of the proinflammatory cytokines IL1β, IL6 and Tnfα and genes involved in de novo steroidogenesis (Stard3 and Cyp11a1), as well as in regeneration of active GCs from their 11-oxo metabolites (Hsd11b1). GF mice showed a generally reduced transcriptional response to immune stress, which was accompanied by decreased intestinal corticosterone production and reduced expression of the GC-sensitive marker Fkbp5. In contrast, the interaction between stress and the microbiota was not detected at the level of plasma corticosterone or the transcriptional response of adrenal steroidogenic enzymes. The results indicate a differential immune stress-induced intestinal response to proinflammatory stimuli and local corticosterone production driven by the gut microbiota.

The ratio of 11β-hydroxysteroid dehydrogenase 1/11β-hydroxysteroid dehydrogenase 2 predicts glucocorticoid response in nasal polyps

BACKGROUND

Glucocorticoids are the first-line medical treatment for chronic rhinosinusitis with nasal polyps (CRSwNP), whose local metabolism is catalyzed by 11β-HSD1 and 11β-HSD2. This study investigates the role of 11β-HSD1 and 11β-HSD2 on the glucocorticoid response of CRSwNP patients and the pathogenic mechanism of these polyps.

METHODS

Forty-three adult CRSwNP patients were enrolled in this study. We evaluated the endoscopic scores by a nasal polyp grading system before and after treatment. We estimated the response to glucocorticoids by the total endoscopic scores. The logistic regression models and inflammatory characteristic curves were conducted to explore the prediction of the response to glucocorticoid in CRSwNP. The expression of 11β-HSD1 and 11β-HSD2 on human sinonasal epithelial cells (HSECS) was measured under the stimulation of toll-like receptor agonists and dexamethasone.

RESULTS

The endoscopic scores in the CRSwNP group declined, the expression of 11β-HSD1/11β-HSD2 increased (r = 0.5276, P = 0.0011), and the cutoff value of the ratio of 11β-HSD1/11β-HSD2 was 0.4654 (sensitivity 79.17%, specificity 88.89%). Dexamethasone induced a decrease in the ratio of 11β-HSD1/11β-HSD2 (P = 0.049) by the stimulation of PGN-BS.

CONCLUSION

We found a strong correlation between the response to glucocorticoids and the ratio of 11β-HSD1/11β-HSD2, which could be used as a marker in predicting the level of tissue response to glucocorticoid therapy in CRSwNP. In addition, PGN-BS could also be a therapeutic target, as it is the negative factor that will decrease the sensitivity of glucocorticoids by reducing the ratio of 11β-HSD1/11β-HSD2.

Design, synthesis, and biological evaluation of novel selective peptide inhibitors of 11β-hydroxysteroid dehydrogenase 1

The enzyme 11β-HSD1 plays a crucial role in the tissue-specific regulation of cortisol levels and it has been associated with various diseases. Inhibition of 11β-HSD1 is an attractive intervention strategy and the discovery of novel selective 11β-HSD1 inhibitors is of high relevance. In this study, we identified and evaluated a new series of selective peptide 11β-HSD1 inhibitors with potential for skin care applications. This novel scaffold was designed with the aid of molecular modeling and two previously reported inhibitors. SAR optimization yielded highly active peptides (IC₅₀ below 400 nM) that were inactive at 1 µM concentration against structurally related enzymes (11β-HSD2, 17β-HSD1 and 17β-HSD2). The best performing peptides inhibited the conversion of cortisone into cortisol in primary human keratinocytes and the most active compound, 5d, was further shown to reverse cortisone-induced collagen damage in human ex-vivo tissue.

11β-hydroxysteroid dehydrogenase-1 deficiency alters brain energy metabolism in acute systemic inflammation

Chronically elevated glucocorticoid levels impair cognition and are pro-inflammatory in the brain. Deficiency or inhibition of 11β-hydroxysteroid dehydrogenase type-1 (11β-HSD1), which converts inactive into active glucocorticoids, protects against glucocorticoid-associated chronic stress- or age-related cognitive impairment. Here, we hypothesised that 11β-HSD1 deficiency attenuates the brain cytokine response to inflammation. Because inflammation is associated with altered energy metabolism, we also examined the effects of 11β-HSD1 deficiency upon hippocampal energy metabolism. Inflammation was induced in 11β-HSD1 deficient (Hsd11b1Del/Del) and C57BL/6 control mice by intraperitoneal injection of lipopolysaccharide (LPS). LPS reduced circulating neutrophil and monocyte numbers and increased plasma corticosterone levels equally in C57BL/6 and Hsd11b1Del/Del mice, suggesting a similar peripheral inflammatory response. However, the induction of pro-inflammatory cytokine mRNAs in the hippocampus was attenuated in Hsd11b1Del/Del mice. Principal component analysis of mRNA expression revealed a distinct metabolic response to LPS in hippocampus of Hsd11b1Del/Del mice. Expression of Pfkfb3 and Ldha, key contributors to the Warburg effect, showed greater induction in Hsd11b1Del/Del mice. Consistent with increased glycolytic flux, levels of 3-phosphoglyceraldehyde and dihydroxyacetone phosphate were reduced in hippocampus of LPS injected Hsd11b1Del/Del mice. Expression of Sdha and Sdhb, encoding subunits of succinate dehydrogenase/complex II that determines mitochondrial reserve respiratory capacity, was induced specifically in hippocampus of LPS injected Hsd11b1Del/Del mice, together with increased levels of its product, fumarate. These data suggest 11β-HSD1 deficiency attenuates the hippocampal pro-inflammatory response to LPS, associated with increased capacity for aerobic glycolysis and mitochondrial ATP generation. This may provide better metabolic support and be neuroprotective during systemic inflammation or aging.

The Role and Regulation of the 11 Beta-Hydroxysteroid Dehydrogenase Enzyme System in Patients with Inflammatory Bowel Disease

INTRODUCTION

Glucocorticoids are known to modulate a number of immunological responses including counteracting inflammation. Within tissues expressing the glucocorticoid and mineralocorticoid receptors including the colon, glucocorticoid metabolism is regulated by the isoenzymes of 11ß-hydroxysteroid dehydrogenase (11β-HSD). 11β-HSD1 acts as an oxidoreductase converting inactive cortisone into active cortisol, while 11β-HSD2 acts as a dehydrogenase converting active cortisol to inactive cortisone. Hexose-6 phosphate dehydrogenase (H6PDH) is a key regulator of 11β-HSD1 activity via its generation of NADPH. Variations in the 11β-HSD enzyme system in relation to levels of expression and regulation may have a role in IBD. The aim of this study was to investigate possible abnormalities of 11β-HSD enzyme system in the colon of patients with IBD.

METHODS

By using quantitative real-time PCR, we investigated the transcription levels of 11β-HSD1 and 2 in colonic tissue from IBD patients and healthy controls undergoing a colonoscopy for disease assessment. Disease activity was recorded using clinical (Mayo Score/Harvey-Bradshaw Index), Biochemical (C-reactive protein), histological, and endoscopic parameters. In addition, transcription levels of H6PDH and the glucocorticoid receptor alpha (GR-α) as well as key pro-inflammatory cytokines (TNF-α, IL-1β, IL-6, Rela (subunit for NF Kappa B)) were later examined among this group, and results were correlated with 11β-HSD2 gene expression. Results and patient demographics were expressed as a mean (and SD), and differences between IBD patients and control groups were analyzed using a Student's t test or Mann-Whitney U test as appropriate, with a p value of ≤0.05 considered significant. Results were controlled for disease activity as outlined above.

RESULTS

Results have demonstrated a significant downregulation in 11β-HSD2 expression in IBD patients compared with controls (13.8 ± 17.1 au vs. 318.4 ± 521.1 au, p = 0.01), whereas levels of 11β-HSD1 did not appear to vary across the two groups. Among IBD patients, there was a trend toward higher 11β-HSD1 expression in inflamed tissue compared with matched non-inflamed tissue (422.1 ± 944 au vs. 102.2 ± 103.9, P = 0.09). Levels of H6PDH and the GR-α expression did not appear to vary among active inflamed IBD tissue and controls. As a result, we examined the association between pro-inflammatory cytokines and levels of 11β-HSD2 expression. Results showed an upregulation of key pro-inflammatory cytokine mRNA expression (TNF-α, IL-1β, IL-6) during inflammation with an associated downregulation of 11β-HSD2 mRNA expression when compared to controls. Dysregulation in this pathway could have a potential role in IBD pathogenesis and may account for exogenous glucocorticoid resistance in IBD. Further work assessing the role of the 11β-HSD enzyme system in steroid-resistant subjects is warranted.

Inflammation regulates 11β-hydroxysteroid dehydrogenase type 1 differentially in specific compartments of the gut mucosal immune system

The bioavailability of glucocorticoids is modulated by enzyme 11β-hydroxysteroid dehydrogenase type 1 (11HSD1), which catalyzes the conversion of inactive 11-oxo-glucocorticoids to active 11-hydroxy-glucocorticoids cortisol and corticosterone and is regulated by pro-inflammatory cytokines. Our aim was to assess the effect of colitis on the expression of 11HSD1 in specific microanatomical compartments of the mucosal immune system. Using qRT-PCR we quantified the expression of 11HSD1 and cytokines in the colon, mesenteric lymph nodes (MLN) and spleen of mice with colitis. Microsamples of the MLN cortex, paracortex and medulla, colonic crypt epithelium (CCE), lamina propria and isolated intestinal lymphoid follicles (ILF) were harvested by laser microdissection, whereas splenic and MLN lymphocytes by flow cytometry. Colitis increased 11HSD1 in the CCE, ILF, and MLN cortex but not in the lamina propria and the MLN paracortex and medulla. Expression of IL-4, IL-21 and TNFα was increased in both the cortex of MLN and ILF, whereas IL-1β and IL-10 were only increased in the follicles. No positive effect was observed in the case of IFNγ and TGFβ. 11HSD1 was positively correlated with TNFα and less strongly with IL-21, IL-1β, and IL-4. Colitis also upregulated the 11HSD1 expression of T cells in the spleen and MLN. The study demonstrates the stimulatory effect of inflammation on local glucocorticoid metabolism only in particular compartments of the mucosal immune system. The correlation between cytokines and 11HSD1 in the ILF and MLN cortex indicates that pro-inflammatory cytokines may amplify glucocorticoid signals in inductive compartments of the mucosal immune system.

Local cortisol/corticosterone activation in skin physiology and pathology

Cortisol and corticosterone are the endogenous glucocorticoids (GCs) in humans and rodents, respectively. Systemic GC is released through the hypothalamic-pituitary-adrenal (HPA) axis in response to various stressors. Over the last decade, extra-adrenal production/activation of cortisol/corticosterone has been reported in many tissues. The enzyme that catalyzes the conversion of hormonally inactive cortisone/11-dehydrocorticosterone (11-DHC) into active cortisol/corticosterone in cells is 11β-hydroxysteroid dehydrogenase (11β-HSD). The 11β-HSD1 isoform is predominantly a reductase, which catalyzes nicotinamide adenine dinucleotide phosphate hydrogen-dependent conversion of cortisone/11-DHC to cortisol/corticosterone, and is widely expressed and present at the highest levels in the liver, lungs, adipose tissues, ovaries, and central nervous system. The 11β-HSD2 isoform, which catalyzes nicotinamide adenine dinucleotide⁺-dependent inactivation of cortisol/corticosterone to cortisone/11-DHC, is highly expressed in distal nephrons, the colon, sweat glands, and the placenta. In healthy skin, 11β-HSD1 is expressed in the epidermis and in dermal fibroblasts. On the other hand, 11β-HSD2 is expressed in sweat glands but not in the epidermis. The role of 11β-HSD in skin physiology and pathology has been reported recently. In this review, we summarize the recently reported role of 11β-HSD in the skin, focusing on its function in cell proliferation, wound healing, inflammation, and aging.

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.

Differential expression of 11β-hydroxysteroid dehydrogenase type 1 and 2 in mild and moderate/severe persistent allergic nasal mucosa and regulation of their expression by Th2 cytokines: asthma and rhinitis

BACKGROUND

Glucocorticoids are used to treat allergic rhinitis, but the mechanisms by which they induce disease remission are unclear. 11β-hydroxysteroid dehydrogenase (11β-HSD) is a tissue-specific regulator of glucocorticoid responses, inducing the interconversion of inactive and active glucocorticoids.

OBJECTIVE

We analysed the expression and distribution patterns of 11β-HSD1, 11β-HSD2, and steroidogenic enzymes in normal and allergic nasal mucosa, and cytokine-driven regulation of their expression. The production levels of cortisol in normal, allergic nasal mucosa and in cultured epithelial cells stimulated with cytokines were also determined.

METHODS

The expression levels of 11β-HSD1, 11β-HSD2, steroidogenic enzymes (CYP11B1, CYP11A1), and cortisol in normal, mild, and moderate/severe persistent allergic nasal mucosa were assessed by real-time PCR, Western blot, immunohistochemistry, and ELISA. The expression levels of 11β-HSD1, 11β-HSD2, CYP11B1, CYP11A1, and cortisol were also determined in cultured nasal epithelial cell treated with IL-4, IL-5, IL-13, IL-17A, and IFN-γ. Conversion ratio of cortisone to cortisol was evaluated using siRNA technique, 11β-HSD1 inhibitor, and the measurement of 11β-HSD1 activity.

RESULTS

The expression levels of 11β-HSD1, CYP11B1, and cortisol were up-regulated in mild and moderate/severe persistent allergic nasal mucosa. By contrast, 11β-HSD2 expression was decreased in allergic nasal mucosa. In cultured epithelial cells treated with IL-4, IL-5, IL-13, and IL-17A, 11β-HSD1 expression and activity increased in parallel with the expression levels of CYP11B1 and cortisol, but the production of 11β-HSD2 decreased. CYP11A1 expression level was not changed in allergic nasal mucosa or in response to stimulation with cytokines. SiRNA technique or the measurement of 11β-HSD1 activity showed that nasal epithelium activates cortisone to cortisol in a 11β-HSD-dependent manner.

CONCLUSIONS AND CLINICAL RELEVANCE

These results indicate that the localized anti-inflammatory effects of glucocorticoids are regulated by inflammatory cytokines, which can modulate the expression of 11β-HSD1, 11β-HSD2, and CYP11B1, and by the intracellular concentrations of bioactive glucocorticoids.

11β-hydroxysteroid dehydrogenases: intracellular gate-keepers of tissue glucocorticoid action

Glucocorticoid action on target tissues is determined by the density of "nuclear" receptors and intracellular metabolism by the two isozymes of 11β-hydroxysteroid dehydrogenase (11β-HSD) which catalyze interconversion of active cortisol and corticosterone with inert cortisone and 11-dehydrocorticosterone. 11β-HSD type 1, a predominant reductase in most intact cells, catalyzes the regeneration of active glucocorticoids, thus amplifying cellular action. 11β-HSD1 is widely expressed in liver, adipose tissue, muscle, pancreatic islets, adult brain, inflammatory cells, and gonads. 11β-HSD1 is selectively elevated in adipose tissue in obesity where it contributes to metabolic complications. Similarly, 11β-HSD1 is elevated in the ageing brain where it exacerbates glucocorticoid-associated cognitive decline. Deficiency or selective inhibition of 11β-HSD1 improves multiple metabolic syndrome parameters in rodent models and human clinical trials and similarly improves cognitive function with ageing. The efficacy of inhibitors in human therapy remains unclear. 11β-HSD2 is a high-affinity dehydrogenase that inactivates glucocorticoids. In the distal nephron, 11β-HSD2 ensures that only aldosterone is an agonist at mineralocorticoid receptors (MR). 11β-HSD2 inhibition or genetic deficiency causes apparent mineralocorticoid excess and hypertension due to inappropriate glucocorticoid activation of renal MR. The placenta and fetus also highly express 11β-HSD2 which, by inactivating glucocorticoids, prevents premature maturation of fetal tissues and consequent developmental "programming." The role of 11β-HSD2 as a marker of programming is being explored. The 11β-HSDs thus illuminate the emerging biology of intracrine control, afford important insights into human pathogenesis, and offer new tissue-restricted therapeutic avenues.

Changing glucocorticoid action: 11β-hydroxysteroid dehydrogenase type 1 in acute and chronic inflammation

Since the discovery of cortisone in the 1940s and its early success in treatment of rheumatoid arthritis, glucocorticoids have remained the mainstay of anti-inflammatory therapies. However, cortisone itself is intrinsically inert. To be effective, it requires conversion to cortisol, the active glucocorticoid, by the enzyme 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1). Despite the identification of 11β-HSD in liver in 1953 (which we now know to be 11β-HSD1), its physiological role has been little explored until recently. Over the past decade, however, it has become apparent that 11β-HSD1 plays an important role in shaping endogenous glucocorticoid action. Acute inflammation is more severe with 11β-HSD1-deficiency or inhibition, yet in some inflammatory settings such as obesity or diabetes, 11β-HSD1-deficiency/inhibition is beneficial, reducing inflammation. Current evidence suggests both beneficial and detrimental effects may result from 11β-HSD1 inhibition in chronic inflammatory disease. Here we review recent evidence pertaining to the role of 11β-HSD1 in inflammation. This article is part of a Special Issue entitled 'CSR 2013'.

Mast cells express 11β-hydroxysteroid dehydrogenase type 1: a role in restraining mast cell degranulation

Mast cells are key initiators of allergic, anaphylactic and inflammatory reactions, producing mediators that affect vascular permeability, angiogenesis and fibrosis. Glucocorticoid pharmacotherapy reduces mast cell number, maturation and activation but effects at physiological levels are unknown. Within cells, glucocorticoid concentration is modulated by the 11β-hydroxysteroid dehydrogenases (11β-HSDs). Here we show expression and activity of 11β-HSD1, but not 11β-HSD2, in mouse mast cells with 11β-HSD activity only in the keto-reductase direction, regenerating active glucocorticoids (cortisol, corticosterone) from inert substrates (cortisone, 11-dehydrocorticosterone). Mast cells from 11β-HSD1-deficient mice show ultrastructural evidence of increased activation, including piecemeal degranulation and have a reduced threshold for IgG immune complex-induced mast cell degranulation. Consistent with reduced intracellular glucocorticoid action in mast cells, levels of carboxypeptidase A3 mRNA, a glucocorticoid-inducible mast cell-specific transcript, are lower in peritoneal cells from 11β-HSD1-deficient than control mice. These findings suggest that 11β-HSD1-generated glucocorticoids may tonically restrain mast cell degranulation, potentially influencing allergic, anaphylactic and inflammatory responses.

Can 11β-hydroxysteroid dehydrogenase activity predict the sensitivity of bone to therapeutic glucocorticoids in inflammatory bowel disease?

In healthy individuals measures of 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) enzyme activity predict the change in bone formation markers in response to therapeutic glucocorticoids. It is unclear whether these measures remain predictive in inflammatory disease. We therefore examined whether 11β-HSD1 activity predicts changes in bone markers and bone mineral density (BMD) in patients with inflammatory bowel disease (IBD) treated with therapeutic glucocorticoids. Prospective and cross-sectional studies were carried out in patients attending a gastroenterology clinic with active (n = 39) or clinically inactive (n = 34) IBD and healthy controls (n = 51). Urinary corticosteroid metabolite profiles were obtained on a spot urine sample and total corticosteroid metabolite excretion and 11β-HSD1 activity (measured as the ratio of tetrahydrocortisol to tetrahydrocortisone metabolites, [THF+alloTHF]/THE) determined. Patients with active disease were treated with an 8-week reducing course of oral prednisolone. The (THF+alloTHF)/THE ratio was significantly increased in patients with IBD, even those in clinical remission. The baseline (THF+alloTHF)/THE ratio failed to predict the decrease in bone formation markers or hip BMD. Measures of 11β-HSD activity do not predict bone loss during glucocorticoid treatment of active IBD, probably due to disease-related increases in 11β-HSD1 activity. Our observation of elevated 11β-HSD1 activity in clinically inactive IBD implicates gastrointestinal glucocorticoid activation in the maintenance of disease remission.

Upregulation of 11β-hydroxysteroid dehydrogenase 1 in lymphoid organs during inflammation in the rat

Glucocorticoids exert anti-inflammatory and immunomodulatory effects that may be regulated in part by the activities of the glucocorticoid-activating and -inactivating enzymes, 11β-hydroxysteroid dehydrogenase type 1 (11HSD1) and type 2 (11HSD2), respectively. Previous studies have demonstrated that inflammatory bowel diseases in humans and experimental animals upregulate 11HSD1 and downregulate 11HSD2. We investigated whether proinflammatory cytokines modulate colonic 11HSDs as well as whether lymphoid organs exhibit any 11HSD response to inflammation. Colon tissue explants exposed to tumor necrosis factor α exhibited an upregulation of 11HSD1 mRNA whereas interleukin 1β downregulated 11HSD2 mRNA. Experimental colitis induced by the intracolonic administration of 2,4,6-trinitrobenzenesulfonic acid stimulated 11HSD1 activity not only in the colon but also in mesenteric lymph nodes and the spleen. Analysis of mRNA for 11HSD1 in colon-draining lymph nodes and the spleen showed that inflammation upregulates the expression of this enzyme in mobile lymphoid cells similar to the intraepithelial and lamina propria leukocytes isolated from the colon. It is inferred that inflammation stimulates the reactivation of glucocorticoids in lymphoid organs and in gut-associated lymphoid tissue.

The impact of inflammation on bone mass in children

Bone is a dynamic tissue. Skeletal bone integrity is maintained through bone modeling and remodeling. The mechanisms underlying this bone mass regulation are complex and interrelated. An imbalance in the regulation of bone remodeling through bone resorption and bone formation results in bone loss. Chronic inflammation influences bone mass regulation. Inflammation-related bone disorders share many common mechanisms of bone loss. These mechanisms are ultimately mediated through the uncoupling of bone remodeling. Cachexia, physical inactivity, pro-inflammatory cytokines, as well as iatrogenic factors related to effects of immunosuppression are some of the common mechanisms. Recently, cytokine signaling through the central nervous system has been investigated for its potential role in bone mass dysregulation in inflammatory conditions. Growing research on the molecular mechanisms involved in inflammation-induced bone loss may lead to more selective therapeutic targeting of these pathological signaling pathways.

11beta-Hydroxysteroid dehydrogenase type 1 is an important regulator at the interface of obesity and inflammation

Systemic glucocorticoid excess, as exemplified by the Cushing syndrome, leads to obesity and all further symptoms of the metabolic syndrome. The current obesity epidemic, however, is not characterized by increased plasma cortisol concentrations, but instead comes along with chronic low-grade inflammation in adipose tissue and concomitant increased levels of 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1, gene HSD11B1), a parameter known to cause obesity in a mouse model. 11beta-HSD1 represents an intracellular amplifier of active glucocorticoid, thus enhances the associated effects on the inflammatory response as well as on nutrient and energy metabolism, and may therefore cause and exacerbate obesity by local increase of glucocorticoid concentrations. Obtained by extensive literature and database searching, the present review includes comprehensive lists of primary glucocorticoid-sensitive genes and gene products as well as of the thus far known regulators of HSD11B1 expression with implication in inflammation and metabolic disease. Collectively, the data clearly show that, in addition to amplifying active glucocorticoid and thus profoundly modulating inflammation and nutrient metabolism, 11beta-HSD1 is subject to tight control of multiple additional immunomodulatory and metabolic regulators. Hence, 11beta-HSD1 acts at the interface of inflammation and obesity and represents an efficient integrator and effector of local inflammatory and metabolic state.

11Beta-hydroxysteroid dehydrogenase type 1 and its role in the hypothalamus-pituitary-adrenal axis, metabolic syndrome, and inflammation

CONTEXT

11Beta-hydroxysteroid dehydrogenase (11beta-HSD) enzymes are now appreciated to be important regulators of hormone action at a tissue level. 11Beta-HSD1 is widely expressed and increases glucocorticoid action through its unique ability to convert inactive glucocorticoids (cortisone in man, 11-dehydrocorticosterone in rodents) to their active forms (cortisol and corticosterone, respectively). The enzyme has roles in the normal hypothalamus-pituitary-adrenal (HPA) axis, has been implicated in metabolic syndrome, and may modulate various aspects of the immune response.

EVIDENCE ACQUISITION

A review of published, peer-reviewed medical literature (1990 to June 2009) on the physiology and pathophysiology of 11beta-HSD1 was performed with an emphasis on HPA axis consequences, the metabolic syndrome, and the inflammatory response.

EVIDENCE SYNTHESIS

Studies of patients with genetic defects in 11beta-HSD1 action show abnormal HPA axis responses with hyperandrogenism being a major consequence. The mechanisms underlying these abnormalities have been explored in mouse models with targeted deletion of components of the 11beta-HSD1 system. A range of experimental studies emphasize the role of 11beta-HSD1 in the metabolic syndrome and the potential for treatment with chemical inhibitors. An emerging area is the role of 11beta-HSD1 in the inflammatory response.

CONCLUSIONS

11Beta-HSD1 activity is an important component of the HPA axis and contributes to the metabolic syndrome and the normal immune response. Ongoing clinical observations and the development of selective inhibitors will further clarify the role of 11beta-HSD1 in these areas.

The role and regulation of 11beta-hydroxysteroid dehydrogenase type 1 in the inflammatory response

Cortisone, a glucocorticoid hormone, was first used to treat rheumatoid arthritis in humans in the late 1940s, for which Hench, Reichstein and Kendall were awarded a Nobel Prize in 1950 and which led to the discovery of the anti-inflammatory effects of glucocorticoids. To be effective, the intrinsically inert cortisone must be converted to the active glucocorticoid, cortisol, by the intracellular action of 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1). Whilst orally administered cortisone is rapidly converted to the active hormone, cortisol, by first pass metabolism in the liver, recent work has highlighted an anti-inflammatory role for 11beta-HSD1 within specific tissues, including in leukocytes. Here, we review recent evidence pertaining to the anti-inflammatory role of 11beta-HSD1 and describe how inhibition of 11beta-HSD1, as widely proposed for treatment of metabolic disease, may impact upon inflammation. Finally, the mechanisms that regulate 11beta-HSD1 transcription will be discussed.

Glucocorticoid availability in colonic inflammation of rat

Recent in vitro studies have shown the involvement of pro-inflammatory cytokines in the regulation of the local metabolism of glucocorticoids via 11beta-hydroxysteroid dehydrogenase type 1 and type 2 (11HSD1 and 11HSD2). However, direct in vivo evidence for a relationship among the local metabolism of glucocorticoids, inflammation and steroid enzymes is still lacking. We have therefore examined the changes in the local metabolism of glucocorticoids during colonic inflammation induced by TNBS and the consequences of corticosterone metabolism inhibition by carbenoxolone on 11HSD1, 11HSD2, cyclooxygenase 2 (COX-2), mucin 2 (MUC-2), tumor necrosis factor alpha (TNF-alpha), and interleukin 1beta (IL-1beta). The metabolism of glucocorticoids was measured in tissue slices in vitro and their 11HSD1, 11HSD2, COX-2, MUC-2, TNF-alpha, and IL-1beta mRNA abundances by quantitative reverse transcription-polymerase chain reaction. Colitis produced an up-regulation of colonic 11HSD1 and down-regulation of 11HSD2 in a dose-dependent manner, and these changes resulted in a decreased capacity of the inflamed tissue to inactivate tissue corticosterone. Similarly, 11HSD1 transcript was increased in colonic intraepithelial lymphocytes of TNBS-treated rats. Topical intracolonic application of carbenoxolone stimulated 11HSD1 mRNA and partially inhibited 11HSD2 mRNA and tissue corticosterone inactivation and these changes were blocked by RU-486. The administration of budesonide mimicked the effect of carbenoxolone. In contrast to the local metabolism of glucocorticoids, carbenoxolone neither potentiates nor diminishes gene expression for COX-2, TNF-alpha, and IL-1beta, despite the fact that budesonide down-regulated all of them. These data indicate that inflammation is associated with the down-regulation of tissue glucocorticoid catabolism. However, these changes in the local metabolism of glucocorticoids do not modulate the expression of COX-2, TNF-alpha, and IL-1beta in inflamed tissue.

11beta-hydroxysteroid dehydrogenase 1 and 2 expression in colon from patients with ulcerative colitis

BACKGROUND AND AIM

11beta-hydroxysteroid dehydrogenase (11betaHSD) is an enzyme responsible for the interconversion of active 11beta-hydroxysteroids (cortisol) into biologically inactive 11-oxosteroids (cortisone). The isoform 11betaHSD1 operates predominantly as a reductase converting cortisone to cortisol, whereas 11betaHSD2 catalyzes oxidation of cortisol to cortisone. This mechanism of peripheral metabolism of glucocorticoids has been suggested to be involved in increasing the availability of anti- inflammatory glucocorticoids as a response to inflammatory stimuli. The aim of this study therefore was to investigate the impact of inflammatory bowel disease on the expression of colonic 11betaHSD1 and 11betaHSD2.

METHODS

Quantitative real-time RT-PCR was used to assess messenger RNA for 11betaHSD1 and 11betaHSD2 in bioptic samples taken from patients with ulcerative colitis and in healthy controls, and in colon of rats with colitis induced by dextran sulfate sodium (DSS). Rat colonic fragments were used for assessment of local metabolism of glucocorticoids.

RESULTS

In both human and rat specimens colitis up-regulated the expression of colonic 11betaHSD1 mRNA and down-regulated 11betaHSD2 mRNA. A similar pattern was observed at the level of local metabolism of corticosterone. Oxidation of corticosterone to 11-dehydrocorticosterone was decreased and reduction of 11-dehydrocorticosterone to corticosterone was increased in colonic tissue of rats with DSS-colitis.

CONCLUSIONS

Colonic inflammation induces local glucocorticoid activation via 11betaHSD1 and impairs glucocorticoid inactivation via 11betaHSD2. The observed changes indicate a role for local metabolism of glucocorticoids in the control of colonic inflammation.

Protection against dextran sodium sulfate-induced colitis by dehydroepiandrosterone and 7alpha-hydroxy-dehydroepiandrosterone in the rat

In this study the anti-oxidant effect of DHEA and 7alpha-hydroxy-DHEA against oxidative stress induced by colitis was investigated in vivo in rats. The two steroids were intraperitoneally injected once daily (50 mg/kg body weight) for 7 days before the induction of colitis that was effected by a daily treatment of 5% (w/v) dextran sodium sulfate (DSS) in drinking water for 7 days. This was quantified by the evidence of weight loss, rectal bleeding, increased wall thickness, and colon length. The inflammatory response was assessed by neutrophil infiltration after a histological examination and myeloperoxidase (MPO) activity measurement. Two markers of oxidative damage were measured in colon homogenates after the onset of DSS treatment: protein carbonyls and thiobarbituric acid-reacting substances. The colonic metabolism of corticosterone by 11beta-hydroxysteroid dehydrogenases types 1 and 2 (11beta-HSD) was investigated in control and treated animals. Results indicated that colitis caused a decrease in body weight and colon length. Severe lesions were observed in the colon with a reduced number of goblet cells which contained less mucins. The lesions were associated with increased MPO activity and oxidative damage. Colonic inflammation down and up regulated the 11beta-HSD2 and 11beta-HSD1, respectively. Treatments by DHEA and 7alpha-hydroxy-DHEA attenuated the inflammatory response when MPO activity decreased; but this did not increase the colonic oxidation of corticosterone into 11-dehydrocorticosterone. Both DHEA and 7alpha-hydroxy-DHEA exerted a significant anti-oxidant effect against oxidative stress induced by colitis through reducing the oxidative damage to proteins and lipids. This resulted in a moderate increase in the amount of colonic mucus. Both DHEA and 7alpha-hydroxy-DHEA may prove useful in the prevention or treatment of colitis.