Development of diagnostic algorithm for Cushing's syndrome: a tertiary centre experience.

PURPOSE: No consensus exists as the gold standard for Cushing's Syndrome (CS) screening. This study aimed to evaluate the diagnostic accuracy and utility of late-night salivary cortisol (LNSC) and cortisone (LNSE), overnight dexamethasone suppression test (ODST), and urinary free cortisol (UFC) in developing a screening algorithm for CS. METHODS: A retrospective, single-centre analysis on 93 adult patients referred to the Oxford Centre for Diabetes, Endocrinology, and Metabolism for CS evaluation (2017-2022). Data were analysed using binomial logistic regression and area under the receiver-operating curve (AUROC). RESULTS: Fifty-three patients were diagnosed with CS. LNSC (sensitivity 87.5%, specificity 64.9%, AUC 0.76), LNSE (sensitivity 72.4%, specificity 85.7%, AUC 0.79), and ODST (sensitivity 94.7%, specificity 52.1%; AUC 0.74) demonstrated comparable effectiveness for CS diagnosis. Their combined application increased diagnostic accuracy (AUC 0.91). UFC was not statistically significant. Pre-test clinical symptom inclusion improved screening test performance (AUC LNSC: 0.83; LNSE: 0.84; ODST: 0.82). For CD diagnosis, LNSE + LNSC (AUC 0.95) outperformed ODST. Combining these with ACTH levels < 12.6 pmol/L perfectly distinguished MACS (AUC 1.00). ODST (AUC 0.76) exhibited superior performance (sensitivity 100.0%, specificity 52.2%) in MACS detection. CONCLUSIONS: LNSC, LNSE, and ODST are robust tools for CS screening, with their combined use offering the highest diagnostic precision. LNSE, especially when used with LNSC, is highly effective for CD diagnosis, exceeding ODST accuracy. ODST is preferable for MACS identification. Integrating ACTH levels markedly improves differentiation between CD and MACS. Conversely, UFC shows limited diagnostic utility.

Glucocorticoids and cognitive function: a walkthrough in endogenous and exogenous alterations.

PURPOSE: The hypothalamic-pituitary-adrenal (HPA) axis exerts many actions on the central nervous system (CNS) aside from stress regulation. Glucocorticoids (GCs) play an important role in affecting several cognitive functions through the effects on both glucocorticoid (GR) and mineralocorticoid receptors (MR). In this review, we aim to unravel the spectrum of cognitive dysfunction secondary to derangement of circulating levels of endogenous and exogenous glucocorticoids. METHODS: All relevant human prospective and retrospective studies published up to 2022 in PubMed reporting information on HPA disorders, GCs, and cognition were included. RESULTS: Cognitive impairment is commonly found in GC-related disorders. The main brain areas affected are the hippocampus and pre-frontal cortex, with memory being the most affected domain. Disease duration, circadian rhythm disruption, circulating GCs levels, and unbalanced MR/GR activation are all risk factors for cognitive decline in these patients, albeit with conflicting data among different conditions. Lack of normalization of cognitive dysfunction after treatment is potentially attributable to GC-dependent structural brain alterations, which can persist even after long-term remission. CONCLUSION: The recognition of cognitive deficits in patients with GC-related disorders is challenging, often delayed, or mistaken. Prompt recognition and treatment of underlying disease may be important to avoid a long-lasting impact on GC-sensitive areas of the brain. However, the resolution of hormonal imbalance is not always followed by complete recovery, suggesting irreversible adverse effects on the CNS, for which there are no specific treatments. Further studies are needed to find the mechanisms involved, which may eventually be targeted for treatment strategies.

Guidelines for the management of glucocorticoids during the peri-operative period for patients with adrenal insufficiency: Guidelines from the Association of Anaesthetists, the Royal College of Physicians and the Society for Endocrinology UK.

These guidelines aim to ensure that patients with adrenal insufficiency are identified and adequately supplemented with glucocorticoids during the peri-operative period. There are two major categories of adrenal insufficiency. Primary adrenal insufficiency is due to diseases of the adrenal gland (failure of the hormone-producing gland), and secondary adrenal insufficiency is due to deficient adrenocorticotropin hormone secretion by the pituitary gland, or deficient corticotropin-releasing hormone secretion by the hypothalamus (failure of the regulatory centres). Patients taking physiological replacement doses of corticosteroids for either primary or secondary adrenal insufficiency are at significant risk of adrenal crisis and must be given stress doses of hydrocortisone during the peri-operative period. Many more patients other than those with adrenal and hypothalamic-pituitary causes of adrenal failure are receiving glucocorticoids as treatment for other medical conditions. Daily doses of prednisolone of 5 mg or greater in adults and 10-15 mg.m-2 hydrocortisone equivalent or greater in children may result in hypothalamo-pituitary-adrenal axis suppression if administered for 1 month or more by oral, inhaled, intranasal, intra-articular or topical routes; this chronic administration of glucocorticoids is the most common cause of secondary adrenal suppression, sometimes referred to as tertiary adrenal insufficiency. A pragmatic approach to adrenal replacement during major stress is required; considering the evidence available, blanket recommendations would not be appropriate, and it is essential for the clinician to remember that adrenal replacement dosing following surgical stress or illness is in addition to usual steroid treatment. Patients with previously undiagnosed adrenal insufficiency sometimes present for the first time following the stress of surgery. Anaesthetists must be familiar with the symptoms and signs of acute adrenal insufficiency so that inadequate supplementation or undiagnosed adrenal insufficiency can be detected and treated promptly. Delays may prove fatal.

Prevalence and severity of non-alcoholic fatty liver disease are underestimated in clinical practice: impact of a dedicated screening approach at a large university teaching hospital.

AIMS: To define the attitudes and current clinical practice of diabetes specialists with regard to non-alcoholic fatty liver disease and, based on the results, implement an evidenced-based pathway for non-alcoholic fatty liver disease assessment. METHODS: An online survey was disseminated to diabetes specialists. Based on findings from this survey, we sought a local solution by launching an awareness campaign and implementing a screening algorithm across all diabetes clinics at a secondary/tertiary referral centre. RESULTS: A total of 133 diabetes specialists responded to the survey. Fewer than 5% of responders correctly assessed the prevalence and severity of advanced fibrotic non-alcoholic fatty liver disease in people with diabetes as 50-75%. Whilst most clinicians performed liver function tests, only 5.7% responded stating that they would use, or had used, a non-invasive algorithm to stage the severity of non-alcoholic fatty liver disease. Implementing a local non-alcoholic fatty liver disease awareness campaign and screening strategy using pre-printed blood request forms, we ensured that 100% (n=395) of all people with Type 1 and Type 2 diabetes mellitus attending secondary/tertiary care diabetes clinics over a 6-month period were appropriately screened for advanced fibrotic non-alcoholic fatty liver disease using the Fib-4 index; 17.9% required further investigation or assessment. CONCLUSIONS: The prevalence and severity of non-alcoholic fatty liver disease are underestimated among diabetes specialists. The Fib-4 index can easily be incorporated into clinical practice in secondary/tertiary care to identify those individuals at risk of advanced fibrosis who require further assessment and who may benefit from a dedicated multidisciplinary approach to their management.

Cortisol metabolism, postnatal depression and weight changes in the first 12 months postpartum.

BACKGROUND & OBJECTIVES: Postnatal depression correlates with postpartum weight retention, and dysregulated cortisol metabolism is evident in depressed individuals. Cortisol metabolism, BMI and metabolic phenotype are robustly associated, but the role of cortisol metabolism in postnatal mental health and weight loss has never been examined. DESIGN: A longitudinal observation. PATIENTS: Forty nine healthy women with uncomplicated pregnancy. MEASUREMENTS: BMI and urinary steroid metabolites at 1 week and 1, 3, 6 and 12 months postpartum. Validated urinary steroid metabolite ratios were measured to determine the activities of 11ß-hydroxysteroid dehydrogenases (11ß-HSD) that interconvert inactive cortisone and active cortisol and the 5α-reductases that clear cortisol to its inactive metabolites. Postnatal depression symptoms were measured at 1, 6 and 12 months. RESULTS: Low 5α-reductase activity was associated with greater weight loss across the first year, independent of demographics, breastfeeding and depression. Postpartum BMI change was unrelated to postnatal depression at any time. Symptoms of postnatal depression were related to higher cortisol metabolite production at 12 months, independent of demographics and breastfeeding. CONCLUSIONS: Greatest weight loss in the postpartum year was associated with lower conversion of cortisone to cortisol and lower conversion of cortisol to its metabolites, supporting previous work that demonstrates the facilitative role of lower 5α-reductase and 11ß-HSD-1 in weight loss. Greater depression symptoms were associated with higher cortisol metabolite production rates. Whilst weight and mental health are both associated with dysregulation of the HPA axis, there may be different pathways towards depressed and obese phenotypes in healthy postpartum samples.

Abdominal subcutaneous adipose tissue insulin resistance and lipolysis in patients with non-alcoholic steatohepatitis.

BACKGROUND: Systemic insulin resistance (IR) is a primary feature in non-alcoholic steatohepatitis (NASH), however, there remain limited data on tissue-specific insulin sensitivity in vivo. METHODS: We examined tissue-specific (adipose, muscle and liver) insulin sensitivity and inflammation in 16 European Caucasian patients with biopsy-confirmed NASH and in 15 healthy controls. All underwent a two-step hyperinsulinaemic euglycaemic clamp incorporating stable isotope measurements of carbohydrate and lipid metabolism with concomitant subcutaneous adipose tissue (SAT) microdialysis. RESULTS: Hepatic and muscle insulin sensitivity were decreased in patients with NASH compared with controls, as demonstrated by reduced suppression of hepatic glucose production and glucose disposal (Gd) rates following insulin infusion. In addition, rates of lipolysis were higher in NASH patients with impaired insulin-mediated suppression of free fatty acid levels. At a tissue specific level, abdominal SAT in patients with NASH was severely insulin resistant, requiring >sixfold more insulin to cause ½-maximal suppression of glycerol release when compared with healthy controls. Furthermore, patients with NASH had significantly higher circulating levels of pro-inflammatory adipocytokines than controls. CONCLUSION: NASH patients have profound IR in the liver, muscle and in particular adipose tissues. This study represents the first in vivo description of dysfunctional SAT in patients with NASH.

Current therapeutic strategies in non-alcoholic fatty liver disease.

Non-alcoholic fatty liver disease (NAFLD) encompasses a spectrum of disease ranging from simple steatosis through steatohepatitis (NASH) to increasing fibrosis and eventual cirrhosis. NAFLD is the hepatic manifestation of the metabolic syndrome and has now become the most common cause of liver disease in Western countries, with the more advanced stages of disease being associated with an increased risk of liver-related morbidity and mortality. The optimal management of patients with NAFLD remains a clinical challenge. The aim of this study is to describe established and emerging strategies for the treatment of NAFLD. Relevant research and review articles were identified by searching PubMed. Selected articles referenced in these publications were also examined. Good quality randomized controlled studies have demonstrated the need for multifaceted lifestyle interventions in patients with NAFLD including the need for diet, exercise and behavioural counselling. Despite several trials of pharmacological agents, no highly effective treatment yet exists, with surgery representing the mainstay for advanced disease. A multidisciplinary approach, with a major focus on lifestyle change, represents best treatment pending the development of new therapeutic options.

Elevated cerebrospinal fluid (CSF) leptin in idiopathic intracranial hypertension (IIH): evidence for hypothalamic leptin resistance?

OBJECTIVE: The aetiology of idiopathic intracranial hypertension (IIH) is not known, but its association with obesity is well-recognized. Recent studies have linked obesity with abnormalities in circulating inflammatory and adiposity related cytokines. The aim of this study was to characterize adipokine and inflammatory cytokine profiles in IIH. DESIGN: Paired serum and cerebrospinal fluid (CSF) specimens were collected from 26 patients with IIH and compared to 62 control subjects. Samples were analysed for leptin, resistin, adiponectin, insulin, IL-1beta, IL-6, IL-8 (CXCL8), TNFalpha, MCP-1 (CCL2), hepatocyte growth factor, nerve growth factor and PAI-1 using multiplex bead immunoassays. RESULTS: CSF leptin was significantly higher in patients with IIH (P = 0.001) compared to controls after correction for age, gender and body mass index (BMI). In the control population, BMI correlated with serum leptin (r = 0.34; P = 0.007) and CSF leptin (r = 0.51; P < 0.0001), but this was not the case for the IIH population. Profiles of other inflammatory cytokines and adipokines did not differ between IIH patients and controls once anthropometric factors had been accounted for. CONCLUSIONS: IIH was characterized by significantly elevated CSF leptin levels which did not correlate with BMI. We suggest that CSF leptin may be important in the pathophysiology of IIH and that obesity in IIH may occur as a result of hypothalamic leptin resistance.

Adrenal suppression in bronchiectasis and the impact of inhaled corticosteroids.

The present study identified three patients with bronchiectasis receiving inhaled corticosteroids (ICSs) who had symptomatic adrenal suppression secondary to ICS. The prevalence of adrenal suppression is unknown in bronchiectasis. The frequency of adrenal suppression and the impact of ICS use in bronchiectasis patients were examined. In total, 50 outpatients (33 receiving ICSs) underwent a short Synacthen test and completed a St George's Respiratory Questionnaire (SGRQ). Symptoms of adrenal suppression, steroid use and lung function were compared between subjects who were suppressed and those who were not. Adrenal suppression was evident in 23.5% of subjects who did not receive ICSs and 48.5% of those who did. Basal cortisol and the increments by which cortisol increased 30 min after Synacthen were lower in suppressed than in nonsuppressed subjects. The incremental cortisol rise was negatively correlated with SGRQ impacts and total score, suggesting a worse quality of life in those who had an impaired adrenal response. The greatest frequency of generalised symptoms was seen in the suppressed group. A significant proportion of subjects with bronchiectasis have evidence of adrenal suppression, and this is increased when inhaled corticosteroids are also used. Impairment of the cortisol response to stimulation is associated with poorer health status.

Corticosteroids, 11beta-hydroxysteroid dehydrogenase isozymes and the rabbit choroid plexus.

The epithelial cells of the choroid plexus (CP) are responsible for cerebrospinal fluid (CSF) secretion into the ventricles of the brain. The balance between CSF production and drainage, in part, facilitates a normal intracranial pressure. The secretion of Na(+) and anions by the CP creates an osmotic gradient driving water into the ventricles. This is opposite to classical Na(+) transporting tissues, such as the kidney, where Na(+) and water reabsorption is mediated by 11beta-hydroxysteroid dehydrogenase type 2 that protects the mineralocorticoid receptor by abrogating active cortisol to inactive cortisone. In the human ocular ciliary epithelium, Na(+) and water secretion is dependent on a novel mediator of ciliary epithelial Na(+) transport, 11beta-HSD type 1 (11beta-HSD1), that generates intraocular cortisol. In a mechanism analogous to that of the embryologically related ocular ciliary epithelium, we propose that autocrine regulation of intracranial cortisol is dependent on 11beta-HSD1 expression in the CP epithelial cells. By conducting immunolocalisation studies on brains from New Zealand White Albino rabbits, we defined the expression of 11beta-HSD1 in the secretory CP epithelial cells. Enzyme assays performed on intact rabbit CP whole tissue explants confirmed predominant 11beta-HSD1 activity, generating cortisol that was inhibited by glycyrrhetinic acid (an 11beta-HSD inhibitor). Using the real time-polymerase chain reaction, rabbit CP tissue was found to express levels of 11beta-HSD1, glucocorticoid receptor alpha and serum and glucocorticoid-regulated kinase 1 mRNA comparable to that expressed in rabbit ocular ciliary body, thereby highlighting the similarity between these two tissues. Furthermore, an enzyme-linked immunosorbent assay of rabbit CSF revealed a median cortisol concentration of 1.7 nmol/l (range 1.4-4.3 nmol/l, n = 9). Our data have identified a functional 11beta-HSD1 within the CP, mediating intracranial cortisol bioavailability. Expression of 11beta-HSD1 may be fundamental in the regulation of CSF secretion and the local generation of cortisol may represent a pathophysiological mechanism underlying cortisol-dependent neuroendocrine diseases.

Dysregulation of 11beta-hydroxysteroid dehydrogenases: implications during pregnancy and beyond.

Glucococorticoids play a critical role in the developmental programing and fetal growth. Key molecules mediating and regulating tissue-specific glucocorticoid actions are 11beta-hydroxysteroid dehydrogenase (11beta-HSD) type 1 and 2 isozymes, both of which are expressed in the placenta and the fetal membranes. 11beta-HSD1 is implicated in the pathogenesis of metabolic syndrome and its dysregulation has been observed in pregnancy-related complications (pre-eclampsia, intrauterine growth restriction). Interestingly, preliminary clinical data have associated certain 11beta-HSD1 gene polymorphisms with hypertensive disorders in pregnancy, suggesting, if confirmed by further targeted studies, it's potential as a putative prognostic marker. Animal studies and observations in humans have confirmed that 11beta-HSD2 insufficiency is related with pregnancy adversity (pre-eclampsia, intrauterine growth restriction, preterm birth). Importantly, down-regulation or deficiency of placental 11beta-HSD2 is associated with significant restriction in fetal growth and low-birth weight, and unfavorable cardio-metabolic profile in adulthood. The potential association of 11beta-HSD1 tissue-specific dysregulation with gestational diabetes, as well as the plausible utility of 11beta-HSD2, as a biomarker of pregnancy adversity and later life morbidity, are emerging areas of intense scientific interest and future investigation.

Expression profiling of 11beta-hydroxysteroid dehydrogenase type-1 and glucocorticoid-target genes in subcutaneous and omental human preadipocytes.

Obesity is associated with increased morbidity and mortality from cardiovascular disease, diabetes and cancer. Although obesity is a multi-factorial heterogeneous condition, fat accumulation in visceral depots is most highly associated with these risks. Pathological glucocorticoid excess (i.e. in Cushing's syndrome) is a recognised, reversible cause of visceral fat accumulation. The aim of this study was to identify depot-specific glucocorticoid-target genes in adipocyte precursor cells (preadipocytes) using Affymetrix microarray technique. Confluent preadipocytes from subcutaneous (SC) and omental (OM) adipose tissue collected from five female patients were treated for 24 h with 100 nM cortisol (F), RNA was pooled and hybridised to the Affymetrix U133 microarray set. We identified 72 upregulated and 30 downregulated genes by F in SC cells. In OM preadipocytes, 56 genes were increased and 19 were decreased. Among the most interesting were transcription factors, markers of adipocyte differentiation and glucose metabolism, cell adhesion and growth arrest protein factors involved in G-coupled and Wnt signalling. The Affymetrix data have been confirmed by quantitative real-time PCR for ten specific genes, including HSD11B1, GR, C/EBPalpha, C/EBPbeta, IL-6, FABP4, APOD, IRS2, AGTR1 and GHR. One of the most upregulated genes in OM but not in SC cells was HSD11B1. The GR was similarly expressed and not regulated by glucocorticoids in SC and OM human preadipocytes. C/EBPalpha was expressed in SC preadipocytes and upregulated by F, but was below the detection level in OM cells. C/EBPbeta was highly expressed both in SC and in OM preadipocytes, but was not regulated by F. Our results provide insight into the genes involved in the regulation of adipocyte differentiation by cortisol, highlighting the depot specifically in human adipose tissue.

11Beta-hydroxysteroid dehydrogenase type 1 in human disease: a novel therapeutic target.

Patients with cortisol excess, Cushing's syndrome, develop a classical phenotype characterized by central obesity, hypertension, and increased cardiovascular mortality. Whilst this observation points to the importance of glucocorticoids, circulating cortisol excess is rare and does not explain the pathogenesis of many common conditions. At a tissue specific level, the enzyme 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) locally regenerates active cortisol from inactive cortisone amplifying glucocorticoid receptor activation in the context of normal circulating cortisol levels. Increased 11beta-HSD1 activity and expression have been implicated in the pathogenesis of many common conditions including, obesity, insulin resistance, the metabolic syndrome, polycystic ovarian syndrome, osteoporosis and glaucoma. Furthermore, selective 11beta-HSD1 inhibition has been proposed as a novel therapeutic strategy in many of these conditions. Here we review the role of 11beta-HSD1 in human disease and discuss the impact of selective 11beta-HSD1 inhibition.

Tissue specific regulation of glucocorticoids in severe obesity and the response to significant weight loss following bariatric surgery (BARICORT).

CONTEXT: Tissue cortisol exposure is under the control of the isozymes of 11ß-hydroxysteroid dehydrogenase (11ß-HSD). 11ß-HSD1 in vivo, acts as an oxoreductase converting inactive cortisone to active cortisol. We hypothesized that 11ß-HSD1 activity is dysregulated in obesity and alters following bariatric surgery induced weight loss in different tissues. METHODS: We recruited 21 patients prior to undergoing bariatric surgery and performed cortisol generation profiles (following oral cortisone administration), urinary corticosteroid metabolite analysis, adipose tissue microdialysis, and tissue gene expression before and after weight loss, following bariatric surgery. Archived tissue samples from 20 previous bariatric surgery patients were also used for tissue gene expression studies. RESULTS: Gene expression showed a positive correlation with 11ß-HSD1 and BMI in omental adipose tissue (OM) (r = +0.52, P = .0001) but not sc adipose tissue (r = +0.28, P = .17). 11ß-HSD1 expression in liver negatively correlated with body mass index (BMI) (r = -0.37, P = .04). 11ß-HSD1 expression in sc adipose tissue was significantly reduced after weight loss (0.41 ± 0.28 vs 0.17 ± 0.1 arbitrary units, P = .02). Following weight loss, serum cortisol generation increased during a cortisol generation profile (area under the curve 26 768 ± 16 880 vs 47 579 ± 16 086 nmol/L/minute, P ≤ .0001.) Urinary corticosteroid metabolites demonstrated a significant reduction in total cortisol metabolites after bariatric surgery (15 224 ± 6595 vs 8814 ± 4824 µg/24 h, P = .01). Microdialysis of sc adipose tissue showed a threefold reduction in cortisol/cortisone ratio after weight loss. CONCLUSIONS: This study highlights the differences in tissue specific regulation of cortisol metabolism in obesity and after weight loss. Following bariatric surgery hepatic 11ß-HSD1 activity increases, sc adipose tissue 11ß-HSD1 activity is reduced and total urinary cortisol metabolites are reduced indicating a possible reduction in hypothalamic pituitary adrenal axis drive. 11ß-HSD1 expression correlates positively with BMI in omental adipose tissue and negatively within hepatic tissue. 11ß-HSD1 expression is reduced in sc adipose tissue after weight loss.

Regulation of expression of 11beta-hydroxysteroid dehydrogenase type 1 in adipose tissue: tissue-specific induction by cytokines.

Patients with glucocorticoid excess develop central obesity, yet in simple obesity, circulating glucocorticoid levels are normal. We have suggested that the increased activity and expression of the enzyme 11beta-hydroxysteroid dehydrogenase type 1 (11betaHSD1) generating active cortisol from cortisone within adipose tissue may be crucial in the pathogenesis of obesity. In this study primary cultures of human hepatocytes and adipose stromal cells (ASC) were used as in vitro models to investigate the tissue-specific regulation of 11betaHSD1 expression and activity. Treatment with tumor necrosis factor-alpha (TNFalpha) caused a dose-dependent increase in 11betaHSD1 activity in primary cultures of both sc [1743.1 +/- 1015.4% (TNFalpha, 10 ng/ml); P < 0.05 vs. control (100%)] and omental [375.8 +/- 57.0% (TNFalpha, 10 ng/ml); P < 0.01 vs. control (100%)] ASC, but had no effect on activity in human hepatocytes [90.2 +/- 2.8% (TNFalpha, 10 ng/ml); P = NS vs. control (100%)]. Insulin-like growth factor I (IGF-I) caused a dose-dependent inhibition of 11betaHSD1 activity in sc [49.7 +/- 15.0% (IGF-I, 100 ng/ml]; P < 0.05 vs. control (100%)] and omental [71.6 +/- 7.5 (IGF-I, 100 ng/ml); P < 0.01 vs. control (100%)] stromal cells, but not in human hepatocytes [101.8 +/- 15.7% (IGF-I, 100 ng/ml); P = NS vs. control (100%)]. Leptin treatment did not alter 11betaHSD1 activity in human hepatocytes, but increased activity in omental ASC [135.8 +/- 14.1% (leptin, 100 ng/ml); P = 0.08 vs. control (100%)]. Treatment with interleukin-1beta induced 11betaHSD1 activity and expression in sc and omental ASC in a time- and dose-dependent manner. 15-Deoxy-12,14-PGJ2, the putative endogenous ligand of the orphan nuclear receptor peroxisome proliferator-gamma, significantly increased 11betaHSD1 activity in omental cells [179.7 +/- 29.6% (1 microM); P < 0.05 vs. control (100%)] and sc [185.3 +/- 12.6% (1 microM); P < 0.01 vs. control (100%)] ASC, and it is possible that expression of this ligand may ensure continued cortisol generation to permit adipocyte differentiation. Protease inhibitors used in the treatment of human immunodeficiency virus infection are known to cause a lipodystrophic syndrome and central obesity, but saquinavir, indinavir, and neflinavir caused a dose-dependent inhibition of 11betaHSD1 activity in primary cultures of human omental ASC. 11betaHSD1 expression is increased in human adipose tissue by TNFalpha, interleukin-1beta, leptin, and orphan nuclear receptor peroxisome proliferator-gamma agonists, but is inhibited by IGF-I. This autocrine and/or paracrine regulation is tissue specific and explains recent clinical data and animal studies evaluating cortisol metabolism in obesity. Tissue-specific 11betaHSD1 regulation offers the potential for selective enzyme inhibition within adipose tissue as a novel therapy for visceral obesity.

Expression of 11beta-hydroxysteroid dehydrogenase type 1 in adipose tissue is not increased in human obesity.

Central obesity is associated with increased morbidity and mortality. Preadipocyte proliferation and differentiation contribute to increases in adipose tissue mass, yet the mechanisms that underlie these processes remain unclear. Patients with glucocorticoid excess develop a reversible form of central obesity, but circulating cortisol levels in idiopathic obesity are invariably normal. We have hypothesized that the enzyme 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1), by converting inactive cortisone to active cortisol in adipose tissue, might be an important autocrine regulator of fat mass. Paired omental and sc fat biopsies were obtained from 32 women (median age, 43 yr; range, 28-65; median body mass index, 27.5 kg/m(2); range, 19.7-39.2) undergoing elective abdominal surgery. 11beta-HSD1 activity and mRNA levels were assessed in whole tissue and in isolated preadipocytes and adipocytes using specific enzyme assays and real-time PCR. Preadipocyte proliferation was measured using tritiated thymidine incorporation. Whole adipose tissue 11beta-HSD1 mRNA levels did not differ between omental and sc samples (P = 0.73). In addition, mRNA levels did not correlate with body mass index (omental: r = 0.1; P = 0.6; sc: r = 0.15; P = 0.4). In keeping with earlier studies, 11beta-HSD1 mRNA levels were higher in omental compared with sc preadipocytes. However, in cultured omental preadipocytes, 11beta-HSD1 activity inversely correlated with body mass index (r = -0.47; P = 0.03). In omental preadipocytes, both cortisol and cortisone decreased proliferation (P < 0.05). Inhibition of 11beta-HSD1 with glycyrrhetinic acid partially reversed the cortisone-induced decrease in preadipocyte proliferation (P < 0.05). Enhanced preadipocyte proliferation within omental adipose tissue as a consequence of decreased 11beta-HSD1 mRNA levels and activity may contribute to increases in visceral adipose tissue mass in obese patients.

11beta-hydroxysteroid dehydrogenase type 1 activity in lean and obese males with type 2 diabetes mellitus.

Glucocorticoids play an important role in the pathogenesis of obesity and insulin resistance. Impaired conversion of cortisone (E) to cortisol (F) by the type 1 isoenzyme of 11beta-hydroxysteroid dehydrogenase (11beta-HSD) in obesity may represent a protective mechanism preventing ongoing weight gain and glucose intolerance. We have studied glucocorticoid metabolism in 33 male subjects with type 2 diabetes mellitus [age, 44.2 +/- 13 yr; body mass index (BMI), 31.1 +/- 7.5 kg/m(2) (mean +/- sd)] and 38 normal controls (age, 41.4 +/- 14 yr; BMI, 38.2 +/- 12.8 kg/m(2)). Circulating F:E ratios were elevated in the diabetic group and correlated with serum cholesterol and homeostasis model assessment-S. There was no difference in 11beta-HSD1 activity between diabetic subjects and controls. In addition, 11beta-HSD1 activity was unaffected by BMI in diabetic subjects. However, in control subjects, increasing BMI was associated with a reduction in the urinary tetrahydrocortisol+5alpha-tetrahydrocortisol:tetrahydrocortisone ratio (P < 0.05) indicative of impaired 11beta-HSD1 activity. The degree of inhibition correlated tightly with visceral fat mass. Changes in 11beta-HSD1 activity could not be explained by circulating levels of adipocytokines. Impaired E to F metabolism in obesity may help preserve insulin sensitivity and prevent diabetes mellitus. Failure to down-regulate 11beta-HSD1 activity in patients with diabetes may potentiate dyslipidemia, insulin resistance, and obesity. Inhibition of 11beta-HSD1 may therefore represent a therapeutic strategy in patients with type 2 diabetes mellitus and obesity.

Cortisol metabolism and the role of 11beta-hydroxysteroid dehydrogenase.

Two isoforms of the enzyme 11beta-hydroxysteroid dehydrogenase (11beta-HSD) interconvert the active glucocorticoid, cortisol, and inactive cortisone. 11beta-HSD1 is believed to act in vivo predominantly as an oxo-reductase using NADP(H) as a cofactor to generate cortisol. In contrast, 11beta-HSD2 acts exclusively as an NAD-dependent dehydrogenase inactivating cortisol to cortisone, thereby protecting the mineralocorticoid receptor from occupation by cortisol. In peripheral tissues, both enzymes serve to control the availability of cortisol to bind to the corticosteroid receptors. Defective expression of 11beta-HSD2 is implicated in patients with hypertension and intra-uterine growth retardation, while 11beta-HSD1 appears to be intricately involved in the conditions of apparent cortisone reductase deficiency, insulin resistance and visceral obesity. The ability of peripheral tissues to regulate corticosteroid concentrations through 11beta-HSD isozymes is established as an important mechanism in the pathogenesis of diverse human diseases. Modulation of enzyme activity may offer a novel therapeutic approach to treating human disease while circumventing the consequences of systemic glucocorticoid excess or deficiency.