11 beta-Hydroxysteroid dehydrogenase 1 activity and gene expression in human adipose stromal cells: effect on aromatase activity

Impact of HSD11B1 polymorphisms on BMI and components of the metabolic syndrome in patients receiving psychotropic treatments

BACKGROUND

Metabolic syndrome (MetS) associated with psychiatric disorders and psychotropic treatments represents a major health issue. 11β-Hydroxysteroid dehydrogenase type 1 (11β-HSD1) is an enzyme that catalyzes tissue regeneration of active cortisol from cortisone. Elevated enzymatic activity of 11β-HSD1 may lead to the development of MetS.

METHODS

We investigated the association between seven HSD11B1 gene (encoding 11β-HSD1) polymorphisms and BMI and MetS components in a psychiatric sample treated with potential weight gain-inducing psychotropic drugs (n=478). The polymorphisms that survived Bonferroni correction were analyzed in two independent psychiatric samples (nR1=168, nR2=188) and in several large population-based samples (n1=5338; n2=123 865; n3>100 000).

RESULTS

HSD11B1 rs846910-A, rs375319-A, and rs4844488-G allele carriers were found to be associated with lower BMI, waist circumference, and diastolic blood pressure compared with the reference genotype (Pcorrected<0.05). These associations were exclusively detected in women (n=257) with more than 3.1 kg/m, 7.5 cm, and 4.2 mmHg lower BMI, waist circumference, and diastolic blood pressure, respectively, in rs846910-A, rs375319-A, and rs4844488-G allele carriers compared with noncarriers (Pcorrected<0.05). Conversely, carriers of the rs846906-T allele had significantly higher waist circumference and triglycerides and lower high-density lipoprotein-cholesterol exclusively in men (Pcorrected=0.028). The rs846906-T allele was also associated with a higher risk of MetS at 3 months of follow-up (odds ratio: 3.31, 95% confidence interval: 1.53-7.17, Pcorrected=0.014). No association was observed between HSD11B1 polymorphisms and BMI and MetS components in the population-based samples.

CONCLUSIONS

Our results indicate that HSD11B1 polymorphisms may contribute toward the development of MetS in psychiatric patients treated with potential weight gain-inducing psychotropic drugs, but do not play a significant role in the general population.

Dietary fructose-related adiposity and glucocorticoid receptor function in visceral adipose tissue of female rats

PURPOSE

Excessive fructose intake coincides with the growing rate of obesity and metabolic syndrome, with women being more prone to these disorders than men. Findings that detrimental effects of fructose might be mediated by glucocorticoid regeneration in adipose tissue only indirectly implicated glucocorticoid receptor (GR) in the phenomenon. The aim of the present study was to elucidate whether fructose overconsumption induces derangements in GR expression and function that might be associated with fructose-induced adiposity in females.

METHODS

We examined effects of fructose-enriched diet on GR expression and function in visceral adipose tissue of female rats. Additionally, we analyzed the expression of genes involved in glucocorticoid prereceptor metabolism [11β-hydroxysteroid dehydrogenase type 1 (11βHSD1) and hexose-6-phosphate dehydrogenase], lipolysis (hormone-sensitive lipase) and lipogenesis (sterol regulatory element binding protein 1 and peroxisomal proliferator-activated receptor γ).

RESULTS

Fructose-fed rats had elevated energy intake that resulted in visceral adiposity, as indicated by increased visceral adipose tissue mass and its share in the whole-body weight. GR hormone binding capacity and affinity, as well as the expression of GR gene at both mRNA and protein levels were reduced in visceral adipose tissue of the rats on fructose diet. The glucocorticoid prereceptor metabolism was stimulated, as evidenced by elevated tissue corticosterone, while the key regulators of lipolysis and lipogenesis remained unaffected by fructose diet.

CONCLUSIONS

The results suggest that the 11βHSD1-mediated elevation of intracellular corticosterone may induce GR downregulation, which may be associated with failure of GR to stimulate lipolysis in fructose-fed female rats.

Induction of 11β-HSD 1 and activation of distinct mineralocorticoid receptor- and glucocorticoid receptor-dependent gene networks in decidualizing human endometrial stromal cells

The actions of glucocorticoids at the feto-maternal interface are not well understood. Here, we show that decidualization of human endometrial stromal cells (HESCs) in response to progesterone and cAMP signaling is associated with a strong induction of 11β-hydroxysteroid dehydrogenase type 1 (11βHSD1) expression and enzyme activity. Decidualization also triggered a gradual decrease in glucocorticoid receptor (GR) expression and reciprocal increase in mineralocorticoid receptor (MR) levels. Gene expression profiling of differentiating HESCs after small interfering RNA (siRNA)-mediated knockdown of either GR or MR identified 239 and 167 significantly regulated genes, respectively. Interestingly, GR-repressed genes were enriched for Krüppel-associated box domain containing zinc-finger proteins, transcriptional repressors involved in heterochromatin formation. In agreement, GR knockdown was sufficient to enhance trimethylated H3K9 levels in decidualizing cells. Conversely, we identified several MR-dependent genes implicated in lipid droplet biogenesis and retinoid metabolism. For example, the induction in differentiating HESCs of DHRS3, encoding a highly conserved enzyme that catalyzes the oxidation/reduction of retinoids and steroids, was enhanced by aldosterone, attenuated in response to MR knockdown, and abolished upon treatment with the MR antagonist RU26752. Furthermore, we demonstrate that decidualization is associated with dynamic changes in the abundance and distribution of cytoplasmic lipid droplets, the formation of which was blocked by RU26752. In summary, progesterone drives local cortisol biosynthesis by decidual cells through induction of 11β-hydroxysteroid dehydrogenase type 1 (11βHSD1), leading to transcriptional regulation of distinct GR and MR gene networks involved in epigenetic programming and lipid and retinoid metabolism, respectively.

Sex hormone effects on physical activity levels: why doesn't Jane run as much as Dick?

The relationship between physical activity levels and disease rates has become an important health-related concern in the developed world. Heart disease, certain cancers and obesity persist at epidemic rates in the US and Western Europe. Increased physical activity levels have been shown to reduce the occurrence of many chronic diseases leading to reductions in the burden on the healthcare system. Activity levels in humans are affected by many cultural and environmental factors; nevertheless, current research points to a strong biological input with potential genetic, neurological and endocrinological origins. Of unique interest, the sex hormones appear to have a very strong influence on activity levels. The current animal literature suggests that females tend to be more active than males due to biological pathways of estrogenic origin. The majority of human epidemiological and anthropological data, on the contrary, suggest women are less active than men in spite of this inherent activity-increasing mechanism. The purpose of this study is to review the current literature regarding the control of physical activity levels by the sex hormones in humans. Using the natural transitional phases of the aging endocrine system, natural periodicity of the menstrual cycle and pharmacological/hormone replacement therapy as variable experimental stages, some authors have been able to provide some information regarding the existence of an inherent activity-increasing mechanism in humans. In brief, activity levels during life stages prior to and after menopause do not significantly differ, despite the vast changes in sex hormone levels and function. Sex hormone differences throughout a regular menstrual cycle do not appear to influence activity levels in humans either; an effect that is pronounced in the female rodent. The use of hormone replacement therapies provides researchers with more systematic controls over hormone modulation in human subjects; however, this benefit comes with additional confounding variables, mostly due to disease or other states of malfunction. Despite the addition of these confounding factors, minor changes to the activity pattern have been observed in women, especially during the initial administration of the therapy. Observations are yet to be made in male subjects during replacement therapy. In general, some evidence exists suggesting that a biological mechanism extending from the sex hormones influences activity in humans. Unfortunately, despite a small number of investigative reports, the paucity of human research investigating how the sex hormones affect activity levels in humans prevents conclusive delineation of the mechanisms involved. Future research in this unique sub-field of endocrinology and exercise science utilizing more appropriate research protocols and effective techniques will provide definitive evidence of such mechanisms.

Expression of cortisol metabolism-related genes shows circadian rhythmic patterns in human adipose tissue

OBJECTIVE

To analyze, in morbid obese patients, the expression of several human genes regulating cortisol metabolism, such as glucocorticoid receptor (GR), 11beta-hydroxysteroid dehydrogenase type 1 (11betaHSD1), 11beta-hydroxysteroid dehydrogenase type 2 (11betaHSD2), stearoyl-acute regulatory protein (StAR), 5alpha-reductase type I (5alpha-R) and peroxisome proliferator-activated receptor-gamma (PPARgamma) in two different adipose depots. A second objective was to characterize the circadian rhythmicity of these genes in both adipose tissue (AT) regions.

DESIGN

Visceral and subcutaneous abdominal AT biopsies were obtained from obese patients (body mass index >or=40 kg m(-2)). To carry out rhythmic expression analysis, AT explants were cultured for 24 h and gene expression at times (T) 0, 6, 12 and 18 h, was performed with quantitative real-time PCR.

RESULT

GR, 11betaHSD1 and PPARgamma genes were highly expressed in both subcutaneous and visceral depots. StAR and 5alpha-R genes were detected at lower levels. The expression of 11betaHSD2 was quantified in both AT depots with a higher expression in the visceral depot (P=0.032). Both sexes had similar gene expression levels, except for 5alpha-R (P=0.002). The genes studied showed circadian rhythmicity being more robust in visceral than in subcutaneous AT. Genes ranged in anti-phase between both depots (P=0.002). This rhythmicity was maintained in an AT culture.

CONCLUSION

We have shown for the first time circadian rhythmicity in glucocorticoid-related gene expression in human AT ex vivo. These results may have potential therapeutic implications with respect to the pathogenesis and treatment of diseases, such as obesity, type 2 diabetes and cardiovascular diseases.

Pathways of adipose tissue androgen metabolism in women: depot differences and modulation by adipogenesis

The objective was to examine pathways of androgen metabolism in abdominal adipose tissue in women. Abdominal subcutaneous (SC) and omental (OM) adipose tissue samples were surgically obtained in women. Total RNA was isolated from whole adipose tissue samples and from primary preadipocyte cultures before and after induction of differentiation. Expression levels of several steroid-converting enzyme transcripts were examined by real-time RT-PCR. Androgen conversion rates were also measured. We found higher expression levels in SC compared with OM adipose tissue for type 1 3beta-hydroxysteroid dehydrogenase (3beta-HSD-1; P < 0.05), for aldo-keto reductase 1C3 (AKR1C3; P < 0.0001), for AKR1C2 (P < 0.0001), and for the androgen receptor (P < 0.0001). 17beta-HSD-2 mRNA levels were lower in SC adipose tissue (P < 0.05). Induction of adipocyte differentiation led to significantly increased expression levels in SC cultures for AKR1C3 (4.7-fold, P < 0.01), 11-cis-retinol dehydrogenase (6.9-fold, P < 0.02), AKR1C2 (5.6-fold, P < 0.004), P-450 aromatase (5.7-fold, P < 0.02), steroid sulfatase (3.1-fold, P < 0.02), estrogen receptor-beta (11.8-fold, P < 0.01), and the androgen receptor (4.0-fold, P < 0.0005). Generally similar but nonsignificant trends were obtained in OM cultures. DHT inactivation rates increased with differentiation, this effect being mediated by dexamethasone alone, through a glucocorticoid receptor-dependent mechanism. In conclusion, higher mRNA levels of enzymes synthesizing and inactivating androgens are found in differentiated adipocytes, consistent with higher androgen-processing rates in these cells. Glucocorticoid-induced androgen inactivation may locally modulate the exposure of adipose cells to active androgens.

Insulin and dexamethasone dynamically regulate adipocyte 11beta-hydroxysteroid dehydrogenase type 1

The adipocyte enzyme 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) amplifies local glucocorticoid action by generating active glucocorticoids from inactive metabolites and has emerged as a key player in the pathogenesis of central obesity and metabolic syndrome. However, the regulation of adipocyte 11beta-HSD1 is incompletely understood. Therefore, the present study was designed to investigate the effects of insulin and glucocorticoid as well as their underlying molecular mechanisms on 11beta-HSD1 activity and expression in 3T3-L1 adipocytes and determine whether the in vitro findings could be confirmed in vivo. Our main in vitro findings are 1) insulin stimulated whereas dexamethasone inhibited 11beta-HSD1 activity and expression in a time- and concentration-dependent manner; 2) the effect of dexamethasone was mimicked by both cortisol and corticosterone but blocked by the glucocorticoid receptor antagonist RU486; 3) the p38 MAPK inhibitor SB220025, but not the ERK inhibitor U0126 or the phosphatidylinositol 3-kinase inhibitor LY294002, prevented insulin stimulation of 11beta-HSD1 activity; and 4) although dexamethasone did not alter the half-life of 11beta-HSD1 mRNA, insulin doubled it. Taken together, these in vitro results demonstrate that insulin stimulates adipocyte 11beta-HSD1 through a posttranscriptional mechanism that involves activation of the p38 MAPK signaling pathway, whereas dexamethasone exerts an opposite effect by a glucocorticoid receptor-mediated transcriptional mechanism. In contrast, both insulin and dexamethasone augmented 11beta-HSD1 activity and expression in rat white adipose tissue in vivo, thus confirming the role of insulin but revealing a fundamental difference regarding the role of dexamethasone in regulating adipocyte 11beta-HSD1 between the two model systems.

Preadipocyte 11beta-hydroxysteroid dehydrogenase type 1 is a keto-reductase and contributes to diet-induced visceral obesity in vivo

Glucocorticoid excess promotes visceral obesity and cardiovascular disease. Similar features are found in the highly prevalent metabolic syndrome in the absence of high levels of systemic cortisol. Although elevated activity of the glucocorticoid-amplifying enzyme 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) within adipocytes might explain this paradox, the potential role of 11beta-HSD1 in preadipocytes is less clear; human omental adipose stromal vascular (ASV) cells exhibit 11beta-dehydrogenase activity (inactivation of glucocorticoids) probably due to the absence of cofactor provision by hexose-6-phosphate dehydrogenase. To clarify the depot-specific impact of 11beta-HSD1, we assessed whether preadipocytes in ASV from mesenteric (as a representative of visceral adipose tissue) and sc tissue displayed 11beta-HSD1 activity in mice. 11beta-HSD1 was highly expressed in freshly isolated ASV cells, predominantly in preadipocytes. 11beta-HSD1 mRNA and protein levels were comparable between ASV and adipocyte fractions in both depots. 11beta-HSD1 was an 11beta-reductase, thus reactivating glucocorticoids in ASV cells, consistent with hexose-6-phosphate dehydrogenase mRNA expression. Unexpectedly, glucocorticoid reactivation was higher in intact mesenteric ASV cells despite a lower expression of 11beta-HSD1 mRNA and protein (homogenate activity) levels than sc ASV cells. This suggests a novel depot-specific control over 11beta-HSD1 enzyme activity. In vivo, high-fat diet-induced obesity was accompanied by increased visceral fat preadipocyte differentiation in wild-type but not 11beta-HSD1(-/-) mice. The results suggest that 11beta-HSD1 reductase activity is augmented in mouse mesenteric preadipocytes where it promotes preadipocyte differentiation and contributes to visceral fat accumulation in obesity.

11 beta-hydroxysteroid dehydrogenase type 1 promotes differentiation of 3T3-L1 preadipocyte

AIM

To investigate the relationship between 11 beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1), a potential link between obesity and type 2 diabetes, and preadipocyte differentiation.

METHODS

Mouse 11beta-HSD1 siRNA plasmids were transfected into 3T3-L1 preadipocytes (a cell line derived from mouse Swiss3T3 cells that were isolated from mouse embryo), for examination of the effect of targeted 11beta-HSD1 inhibition on differentiation of 3T3-L1 cells. Differentiation was stimulated with 3-isobutyl-1-methyxanthine, insulin, and dexamethasone. The transcription level of the genes was detected by real-time PCR.

RESULTS

Lipid accumulation was significantly inhibited in cells transfected with mouse 11beta-HSD1 siRNA compared with non-transfected 3T3-L1 cells. Fewer lipid droplets were detected in the transfected cells both prior to stimulation and after stimulation with differentiation-inducing reagents. The expression of adipocyte differentiation-associated markers such as lipoprotein lipase and fatty acid synthetase were downregulated in the transfected cells. Similarly, the expression of preadipocyte factor-1, an inhibitor of adipocyte differentiation, was downregulated upon stimulation of differentiation and had no changes in the transfected cells.

CONCLUSION

11 beta-HSD1 can promote preadipocyte differentiation. Based on this, we propose that 11 beta-HSD1 may be an important candidate mediator of obesity and obesity-induced insulin resistance.

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.

Complex actions of sex steroids in adipose tissue, the cardiovascular system, and brain: Insights from basic science and clinical studies

Recent publications describing the results of the Women's Health Initiative (WHI) and other studies reporting the impact of hormone therapy on aging women have spurred reexamination of the broad use of estrogens and progestins during the postmenopausal years. Here, we review the complex pharmacology of these hormones, the diverse and sometimes opposite effects that result from the use of different estrogenic and progestinic compounds, given via different delivery routes in different concentrations and treatment sequence, and to women of different ages and health status. We examine our new and growing appreciation of the role of estrogens in the immune system and the inflammatory response, and we pose the concept that estrogen's interface with this system may be at the core of some of the effects on multiple physiological systems, such as the adipose/metabolic system, the cardiovascular system, and the central nervous system. We compare and contrast clinical and basic science studies as we focus on the actions of estrogens in these systems because the untoward effects of hormone therapy reported in the WHI were not expected. The broad interpretation and publicity of the results of the WHI have resulted in a general condemnation of all hormone replacement in postmenopausal women. In fact, careful review of the extensive literature suggests that data resulting from the WHI and other recent studies should be interpreted within the narrow context of the study design. We argue that these results should encourage us to perform new studies that take advantage of a dialogue between basic scientists and clinician scientists to ensure appropriate design, incorporation of current knowledge, and proper interpretation of results. Only then will we have a better understanding of what hormonal compounds should be used in which populations of women and at what stages of menopausal/postmenopausal life.

Effect of nutrient ingestion on total-body and splanchnic cortisol production in humans

The splanchnic bed produces cortisol at rates approximating extraadrenal tissues by converting cortisone to cortisol via the 11beta-hydroxysteroid dehydrogenase (11beta-HSD) type 1 pathway. It is not known whether splanchnic cortisol production is regulated by nutrient ingestion and/or by the accompanying changes in hormone secretion. To address this question, 18 healthy humans were randomized to ingest either a mixed meal or to receive an intravenous saline infusion while total-body, splanchnic, and D3 cortisol production (an index of 11beta-HSD type 1 activity) were measured using the combined hepatic catheterization and D4 cortisol infusion methods. Fasting glucose and insulin concentrations did not differ on the meal and saline study days. Glucose and insulin concentrations increased after meal ingestion, peaking at 11.0 +/- 1.0 mmol/l and 451 +/- 64 pmol/l, respectively, at 45 min, then fell to baseline thereafter. In contrast, glucose and insulin concentrations slowly fell to 5.1 +/- 0.1 mmol/l and 27 +/- 6 pmol/l during the 6 h of observation on the saline study day. Fasting cortisol concentration did not differ on the meal and saline study days. Cortisol increased (P < 0.05) to a peak of 353 +/- 55 nmol/l after meal ingestion but did not change after saline infusion. The increase in cortisol after meal ingestion was associated with an increase in both total body cortisol (from 748 +/- 63 to 1,620 +/- 235 nmol/min; P < 0.01) and total body D3 cortisol (from 99 +/- 11 to 143 +/- 11 nmol/min; P < 0.01) production, whereas there was no change in either on the saline study day. The increase in total-body cortisol and D3 cortisol production after meal ingestion originated in extrasplanchnic tissues since splanchnic cortisol production (mean 0-360 min: 254 +/- 83 vs. 262 +/- 36 nmol/min) and splanchnic D3 cortisol production (mean 0-360 min: 72 +/- 22 vs. 77 +/- 14 nmol/min) did not differ on the meal and saline study days. We conclude that ingestion of a mixed meal does not alter either splanchnic cortisol production or the conversion of D4 cortisol to D3 cortisol or, therefore by implication, flux via the splanchnic 11beta-HSD type 1 pathway.

Inhibition of 11beta-hydroxysteroid dehydrogenase type 1 in obesity

Excessive glucocorticoid exposure (Cushing's syndrome) results in increased adiposity associated with dysmetabolic features (including insulin resistance, hyperlipidaemia, and hypertension). Circulating cortisol levels are not elevated in idiopathic obesity, although cortisol production and clearance are increased. However, tissue glucocorticoid exposure may be altered independently of circulating levels by 11beta-hydroxysteroid dehydrogenase type 1 (11HSD1), an enzyme which generates active glucocorticoid within tissues, including in adipose tissue. Transgenic overexpression of 11HSD1 in mice causes obesity. In human obesity, 11HSD1 is altered in a tissue-specific manner with reduced levels in liver but elevated levels in adipose, which may lead to glucocorticoid receptor activation and contribute to the metabolic phenotype. The reasons for altered 11HSD1 in obesity are not fully understood. Although some polymorphisms have been demonstrated in intronic and upstream regions of the HSD11B1 gene, the functional significance of these is not clear. In addition, there is mounting evidence that 11HSD1 may be dysregulated secondarily to factors that are altered in obesity, including substrates for metabolism, hormones, and inflammatory mediators. 11HSD1 is a potential therapeutic target for the treatment of the metabolic syndrome. 11HSD1 knockout mice are protected from diet-induced obesity and associated metabolic dysfunction. Although many specific inhibitors of 11HSD1 have now been developed, and published data support their efficacy in the liver to reduce glucose production, their efficacy in enhancing insulin sensitivity in adipose tissue remains uncertain. The therapeutic potential of 11HSD1 in human obesity therefore remains highly promising but as yet unproven.

GH effect on enzyme activity of 11betaHSD in abdominal obesity is dependent on treatment duration

OBJECTIVE

In the past years the interaction of GH and 11beta hydroxysteroid dehydrogenase (11betaHSD) in the pathogenesis of central obesity has been suggested.

DESIGN

We studied the effects of 9 months of GH treatment on 11betaHSD activity and its relationship with body composition and insulin sensitivity in 30 men with abdominal obesity, aged 48-66 years, in a randomised, double-blind, placebo-controlled trial.

METHODS

Urinary steroid profile was used to estimate 11betaHSD type 1 and 2 (11betaHSD1 and 11betaHSD2) activities. Abdominal s.c. and visceral adipose tissues were measured using computed tomography. Glucose disposal rate (GDR) obtained during a euglycaemic-hyperinsulinaemic glucose clamp was used to assess insulin sensitivity.

RESULTS

In the GH-treated group the 11betaHSD1 activity decreased transiently after 6 weeks (P < 0.01) whereas 11betaHSD2 increased after 9 months of treatment (P < 0.05). Between 6 weeks and 9 months, GDR increased and visceral fat mass decreased. Changes in 11betaHSD1 correlated with changes in visceral fat mass between baseline and 6 weeks. There were no significant correlations between 11betaHSD1 and 11betaHSD 2 and changes in GDR.

DISCUSSION

The study demonstrates that short- and long-term GH treatment has different effects on 11betaHSD1 and 11betaHSD2 activity. Moreover, the data do not support that long-term metabolic effects of GH are mediated through its action on 11betaHSD.

11β-Hydroxysteroid dehydrogenase Type 1 as a novel therapeutic target in metabolic and neurodegenerative disease

11beta-hydroxysteroid dehydrogenase Type 1 (11HSD1) catalyses regeneration of active 11-hydroxy glucocorticoids from inactive 11-keto metabolites within target tissues. Inhibition of 11HSD1 has been proposed as a novel strategy to lower intracellular glucocorticoid concentrations, without affecting circulating glucocorticoid levels and their responsiveness to stress. Increased 11HSD1 activity may be pathogenic, for example, in adipose tissue in obesity. Experiments in transgenic mice and using prototype inhibitors in humans show benefits of 11HSD1 inhibition in liver, adipose and brain tissue in treating features of the metabolic syndrome and cognitive dysfunction with ageing. The clinical development of potent selective 11HSD1 inhibitors is now a high priority.

11beta-hydroxysteroid dehydrogenase type 1: a tissue-specific regulator of glucocorticoid response

11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) interconverts inactive cortisone and active cortisol. Although bidirectional, in vivo it is believed to function as a reductase generating active glucocorticoid at a prereceptor level, enhancing glucocorticoid receptor activation. In this review, we discuss both the genetic and enzymatic characterization of 11beta-HSD1, as well as describing its role in physiology and pathology in a tissue-specific manner. The molecular basis of cortisone reductase deficiency, the putative "11beta-HSD1 knockout state" in humans, has been defined and is caused by intronic mutations in HSD11B1 that decrease gene transcription together with mutations in hexose-6-phosphate dehydrogenase, an endoluminal enzyme that provides reduced nicotinamide-adenine dinucleotide phosphate as cofactor to 11beta-HSD1 to permit reductase activity. We speculate that hexose-6-phosphate dehydrogenase activity and therefore reduced nicotinamide-adenine dinucleotide phosphate supply may be crucial in determining the directionality of 11beta-HSD1 activity. Therapeutic inhibition of 11beta-HSD1 reductase activity in patients with obesity and the metabolic syndrome, as well as in glaucoma and osteoporosis, remains an exciting prospect.

Splanchnic cortisol production occurs in humans: evidence for conversion of cortisone to cortisol via the 11-beta hydroxysteroid dehydrogenase (11beta-hsd) type 1 pathway

Glucocorticoids are potent regulators of protein, fat, and carbohydrate metabolism. To determine if cortisol production occurs within the splanchnic bed in humans, 11 nondiabetic subjects were studied using the hepatic/leg catheterization method along with an infusion of [9,11,12,12-2H4] cortisol (D4-cortisol) as proposed by Andrews et al. In the fasting state, there was net release (P < 0.05) of cortisol from the splanchnic bed (6.1 +/- 2.6 microg/min) and net uptake (P < 0.05) by the leg (1.7 +/- 0.7 microg/min). This, along with cortisol production by other tissues (e.g., the adrenals), resulted in a total-body cortisol appearance rate of 18.1 +/- 1.9 microg/min. Fractional splanchnic D4-cortisol extraction averaged 12.9 +/- 1.3% (P < 0.001), splanchnic cortisol uptake 14.8 +/- 2.0 microg/min (P < 0.001), and splanchnic cortisol production 22.2 +/- 3.3 microg/min (P < 0.001). On the other hand, fractional leg D4-cortisol extraction averaged 5.6 +/- 1.8% (P < 0.02), leg cortisol uptake 2.3 +/- 0.7 microg/min (P < 0.01), and leg cortisol production 0.4 +/- 0.4 microg/min, which did not differ from zero. Because D4-cortisol loses a deuterium during conversion to [9,12,12-2H3] cortisone (D3-cortisone), which in turn generates [9,12,12(2)H3] cortisol (D3-cortisol) via 11-beta hydroxysteroid dehydrogenase (11beta-HSD) type 1, D3-cortisol production can be used as an index of 11beta-HSD type 1 activity. Net splanchnic D3-cortisol release (3.9 +/- 0.4 microg/min) and splanchnic D3-cortisol production (7.1 +/- 0.7 microg/min) occurred (P < 0.01) in all subjects. In contrast, there was minimal leg D3-cortisol production (0.04 +/- 0.01 microg/min), resulting in a strong correlation between splanchnic D3-cortisol production and total-body 3D-cortisol production in both the fasting state (r = 0.84; P < 0.02) and during an infusion of insulin (r = 0.97; P < 0.01). Thus, splanchnic production of cortisol occurs in nondiabetic humans at rates approximating that which occurs in the remainder of the body. These data support the possibility that alterations in splanchnic cortisol production contribute to visceral fat accumulation and the hepatic insulin resistance of obesity or type 2 diabetes.

Regulation of 11beta-HSD genes in human adipose tissue: influence of central obesity and weight loss

OBJECTIVES

The activity of adipose 11beta-hydroxysteroid dehydrogenase (11beta-HSD) 1 is increased in obese subjects, and animal data suggest that increased cortisol formation in adipose tissue contributes to the development of the metabolic syndrome. The aim of this study was to determine whether up-regulation of human adipose 11beta-HSD1 in obesity can also be found at the gene expression level.

RESEARCH METHODS AND PROCEDURES

11beta-HSD gene expression in subcutaneous adipose tissue biopsies of 70 postmenopausal women was studied by real-time reverse-transcription polymerase chain reaction. The influence of weight reduction and in vitro effects of several modulators of adipocyte gene expression on 11beta-HSD genes in human adipocytes were also studied.

RESULTS

The 11beta-HSD1 gene was highly expressed in human adipose tissue. 11beta-HSD2 mRNA was also detectable at lower levels. Adipose 11beta-HSD1 gene expression was increased by two-fold and was positively correlated with waist circumference and homeostasis model assessment index of insulin resistance. 11beta-HSD2 gene expression was reduced by half in obese women. Weight reduction did not change gene expression levels of 11beta-HSD1 or 11beta-HSD2. Cortisol increased 11beta-HSD1 gene expression in isolated human adipocytes in vitro, whereas estradiol, triiodothyronine, angiotensin II, and pioglitazone had no influence.

DISCUSSION

Our data suggest that increased expression of the 11beta-HSD1 gene is associated with metabolic abnormalities in obese women and that increased expression of this gene may contribute to the previously reported increased local conversion of cortisone to cortisol in adipose tissue of obese individuals.

11 beta-hydroxysteroid dehydrogenase type 1 in obesity and the metabolic syndrome

11 beta-Hydroxysteroid dehydrogenase type 1 (11HSD1) catalyses the in vivo conversion of inactive to active glucocorticoids. It is a widespread, highly regulated enzyme which amplifies the ligand available for intracellular glucocorticoid receptors. Excessive glucocorticoid exposure causes central obesity, hypertension, dyslipidaemia and insulin resistance, as seen with elevated plasma cortisol in Cushing's syndrome. Transgenic mice over-expressing 11HSD1 in their white adipose tissue are obese, hypertensive, dyslipidaemic and insulin resistant. Further, 11HSD1 knockout mice are protected from these metabolic abnormalities. In human idiopathic obesity, circulating cortisol levels are not elevated but 11HSD1 mRNA and activity is increased in subcutaneous adipose. The impact of increased adipose 11HSD1 on pathways leading to metabolic complications remains unclear in humans. Pharmacological inhibition of 11HSD1 has been achieved in liver with carbenoxolone, which enhances hepatic insulin sensitivity. Newer selective 11HSD1 inhibitors are in development, which may achieve reduced cortisol action in adipose tissue and confer therapeutic benefit in obese patients.

Local androgen inactivation in abdominal visceral adipose tissue

We examined the expression and activity of two enzymes from the aldoketoreductase (AKR) family 1C, namely type 5 17beta-hydroxysteroid dehydrogenase (17beta-HSD-5, AKR1C3) and type 3 3alpha-hydroxysteroid dehydrogenase (3alpha-HSD-3, AKR1C2) in female sc and omental adipose tissue and in preadipocyte primary cultures. 17beta-HSD-5 preferentially synthesizes testosterone from the inactive adrenal precursor androstenedione, whereas 3alpha-HSD-3 inactivates dihydrotestosterone. mRNAs of both enzymes were detected in adipose tissue from the omental and sc compartments. Real-time PCR quantification indicated a 3-fold higher 3alpha-HSD-3 expression compared with 17beta-HSD-5, and the expression of both enzymes tended to be higher in the sc vs. the omental depot. Accordingly, dose-response and time-course experiments performed in preadipocyte primary cultures indicated that 3alpha-HSD activity was higher than 17beta-HSD activity (13-fold maximum velocity difference). We measured 3alpha-HSD activity in omental and sc adipose tissue samples of 32 women for whom body composition and body fat distribution were evaluated by dual-energy x-ray absorptiometry and CT, respectively. We found that androgen inactivation in omental adipose tissue through 3alpha-HSD activity was significantly higher in women with elevated vs. low visceral adipose tissue accumulation (1.7-fold difference; P < 0.05). Moreover, omental adipose tissue 3alpha-HSD activity was positively and significantly associated with CT-measured visceral adipose tissue (r = 0.43; P < 0.02) and omental adipocyte diameter (r = 0.42; P < 0.02). These results indicate that local androgen inactivation is a predominant reaction in female abdominal adipose tissue, with the greatest conversion rates observed in the presence of abdominal visceral obesity. Increased androgen inactivation in omental adipose tissue of abdominally obese women may impact locally on the regulation of adipocyte metabolism.

The inflammatory response is an integral part of the stress response: Implications for atherosclerosis, insulin resistance, type II diabetes and metabolic syndrome X

In previous publications, we presented the hypothesis that repeated episodes of acute or chronic psychological stress could induce an acute phase response (APR) and subsequently a chronic inflammatory process such as atherosclerosis. In this paper, that hypothesis, namely that such stress can induce an APR and inflammation, has been extended to include a chronic inflammatory process(s), characterized by the presence of certain cytokines and acute phase reactants (APR), which is associated with certain metabolic diseases. The loci of origin of these cytokines, particularly interleukin 6 (IL-6), and their induction, has been considered. Evidence is presented that the liver, the endothelium, and fat cell depots are the primary sources of cytokines, particularly IL-6, and that IL-6 and the acute phase protein (APP), C-reactive protein (CRP), are strongly associated with, and likely play a dominant role in, the development of this inflammatory process which leads to insulin resistance, non-insulin dependent diabetes mellitus type II, and Metabolic syndrome X. The possible role of psychological stress and the major stress-related hormones as etiologic factors in the pathogenesis of these metabolic diseases, as well as atherosclerosis, is discussed. The fact that stress can activate an APR, which is part of the innate immune inflammatory response, is evidence that the inflammatory response is contained within the stress response or that stress can induce an inflammatory response. The evidence that the stress, inflammatory, and immune systems all evolved from a single cell, the phagocyte, is further evidence for their intimate relationship which almost certainly was maintained throughout evolution.

Relationship between sex hormone-binding globulin levels and features of the metabolic syndrome

Previous studies have demonstrated that reduced plasma levels of sex hormone-binding globulin (SHBG) are related to alterations in several features of the metabolic syndrome in both men and women. We investigated whether SHBG level was a global predictor of the metabolic syndrome in a sample of 203 men, 173 premenopausal, and 46 postmenopausal women for whom we also obtained a detailed assessment of the metabolic profile, including body composition (hydrostatic weighing), abdominal adipose tissue areas (computed tomography), plasma lipid-lipoprotein levels, and glucose homeostasis (oral glucose challenge). Low SHBG levels were associated with increased total and abdominal adiposity in men as well as in pre- and postmenopausal women. Low SHBG levels were also associated with an altered metabolic profile, especially in premenopausal women. Subjects were subdivided according to the presence of 0, 1 to 2, or 3 or more features of the metabolic syndrome. Twenty-five percent of men were characterized by 3 features or more, whereas most premenopausal women (61.3%) had a healthy metabolic profile (0 features) and 6.9% were characterized by 3 or more features. Most postmenopausal women (54.3%) were characterized by 1 to 2 components of the metabolic syndrome, and 13.0% were characterized by 3 or more components. The proportion of subjects characterized by the metabolic syndrome (3 components or more) was lower in subjects with SHBG values in the upper tertile compared with the lower tertile in both men and premenopausal women (17.7% v 28.4% and 1.7% v 14.0%, respectively). Logistic regression analyses indicated that an SHBG level in the upper tertile was associated with a significant reduction in the probability of being characterized by the metabolic syndrome (odds ratios of 0.35, P =.02 for men and.11, P =.05 for premenopausal women, with the lower tertile as a reference). The logistic regression was not significant in postmenopausal women. These results suggest that plasma SHBG level may represent a significant predictor of the metabolic syndrome in men and premenopausal women.

The functional roles of 11 beta-HSD1: vascular tissue, testis and brain

Glucocorticoid hormones bind both glucocorticoid receptor (GR) and mineralocorticoid receptor (MR) exerting a broad spectrum of actions in various tissues. The concentrations of glucocorticoid hormones in the target cells are regulated by 11 beta-hydroxysteroid dehydrogenases, type 1 (11 beta-HSD1) and type 2 (11 beta-HSD2). 11 beta-HSD2 is a unidirectional dehydrogenase, which inactivates biologically active glucocorticoid into inert metabolite, while 11 beta-HSD1 is a bi-directional oxidoreductase, which either inactivates biologically active glucocorticoid or activates inert metabolite into active forms. GRs and MRs are present in various tissues and mediate a broad spectrum of physiological actions. The co-existence of 11 beta-HSD1 with these two types of receptors plays an important role in regulation of glucocorticoid actions. This review examines the roles of 11 beta-HSD1 in vascular tissues, testis, brain and other tissues such as placental, retinal and adipose tissues.

Is 11beta-hydroxysteroid dehydrogenase type 1 a therapeutic target? Effects of carbenoxolone in lean and obese Zucker rats

In liver and adipose tissue, 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) regenerates glucocorticoids from inactive 11-keto metabolites. Pharmacological inhibition or transgenic disruption of 11beta-HSD1 attenuates glucocorticoid action and increases insulin sensitivity. Increased adipose 11beta-HSD1 may also contribute to the metabolic complications of obesity. Here, we examine the effects of inhibition of 11beta-HSDs with carbenoxolone in obese insulin-resistant Zucker rats, a strain in which tissue-specific dysregulation of 11beta-HSD1 (increased in adipose, decreased in liver) mirrors changes in human obesity. Six-week-old male rats were treated orally with carbenoxolone (50 mg/kg/day) or water (1 ml/kg/day) for 3 weeks. Carbenoxolone inhibited 11beta-HSD1 activity in liver (25 +/- 3 versus 52 +/- 2% conversion in lean; 18 +/- 3 versus 35 +/- 3% in obese; p < 0.01) but not in adipose tissue or skeletal muscle. Carbenoxolone had no effect on weight gain or food intake, did not affect plasma glucose during an oral glucose tolerance test, and increased the plasma insulin response to glucose. However, high-density lipoprotein cholesterol was increased by carbenoxolone in obese animals (1.52 +/- 0.24 versus 1.21 +/- 0.26 mM; p < 0.03). Carbenoxolone did not inhibit hepatic inactivation of glucocorticoid by 5beta-reductase and had no significant effect on plasma corticosterone levels. In conclusion, carbenoxolone provides a model for liver-specific inhibition of 11beta-HSD1, which results in improved lipid profile, in Zucker obese rats. Failure to inhibit 11beta-HSD1 in adipose tissue and/or skeletal muscle may explain the lack of effect on glucose tolerance and obesity. Inhibition of adipose 11beta-HSD1 is probably necessary to gain the maximum benefit of an 11beta-HSD1 inhibitor.

Intracrine induction of 11beta-hydroxysteroid dehydrogenase type 1 expression by glucocorticoid potentiates prostaglandin production in the human chorionic trophoblast

Glucocorticoids are involved in the modulation of the release of parturition hormones from the fetal membranes and placenta, where their actions are determined by the prereceptor glucocorticoid metabolizing enzyme 11beta-hydroxysteroid dehydrogenase (11beta-HSD). Two distinct isozymes of 11beta-HSD have been characterized. In the fetal membranes, 11beta-HSD1 is the predominate isozyme; it converts biologically inert 11-ketone glucocorticoid metabolites into active glucocorticoids. Sequence analysis of the cloned 11beta-HSD1 gene revealed a putative glucocorticoid response element in the promoter region. However, whether glucocorticoids modulate 11beta-HSD1 expression in the fetal membranes is unknown. In this study, 11beta-HSD1 and glucocorticoid receptor (GR) were coexpressed in the chorionic trophoblast. Radiometric conversion assay and Northern blot analysis revealed that both 11beta-HSD1 reductase activity and mRNA levels were increased by dexamethasone (1 microM, 0.1 microM) in the cultured chorionic trophoblast, and the effects were blocked by GR antagonist RU486 (1 microM). Prior induction of 11beta-HSD1 by dexamethasone potentiated the subsequent stimulation of prostaglandin H synthetase 2 expression and secretion of prostaglandin E(2) by cortisone in the chorionic trophoblast. There is colocalization of 11beta-HSD1 and GR in the chorionic trophoblast. By binding to GR, glucocorticoids induce the expression of 11beta-HSD1 by a possible intracrine mechanism, thereby amplifying the actions of glucocorticoids on prostaglandin production in the fetal membranes. This cascade of events initiated by glucocorticoids may play an important role in the positive feed-forward mechanisms of labor.

Leptin and the adipocyte endocrine system

Although adipose tissue has long been considered to be metabolically passive and primarily responsible for energy storage, recent scientific advances have dramatically altered our understanding of the function of this ubiquitous tissue. The fat cell is a transducer of energy supply for the changing metabolic needs of the body, modulating glucose homeostasis, hypothalamic function, sympathetic output, vascular tone, immune response, and reproduction. Through endocrine/autocrine and paracrine actions, adipocyte-derived molecules defend the body during periods of energy deficit and stress. With the development of obesity, maladaptive responses to adipose excess result in pathologic states of inflammation, coagulopathy, and altered insulin sensitivity.

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

11beta-Hydroxysteroid dehydrogenases (11beta HSDs) are enzymes that catalyse the interconversion of active glucocorticoids (cortisol and corticosterone) into their inactive 11-keto products (cortisone and 11-deoxycorticosterone). Two isozymes have been identified: 11beta HSD type 1 is a predominant reductase, reactivating glucocorticoids from inert metabolites, whereas 11beta HSD type 2 is a potent dehydrogenase, inactivating glucocorticoids. They play a major role in the modulation of local cortisol levels and hence access of active steroid to corticosteroid receptors. This review focuses on the clinical importance of 11beta HSDs. We describe recent research that has not only advanced our understanding of the physiological role of these enzymes, but also their role in common diseases, including primary obesity and essential hypertension. These data provide encouragement that novel therapies will arise from a fuller understanding of the 11beta HSD system.

Gender differences in the regulation of P450 aromatase expression and activity in human adipose tissue

OBJECTIVE

To investigate the hormonal regulation of P450 aromatase activity (responsible for the conversion of C19 androgens to C18 oestrogens) in human adipose tissue from men and pre- and post-menopausal women.

SUBJECTS

Subcutaneous abdominal adipose tissue was obtained from 19 subjects: six pre-menopausal females (mean age 41.8+/-(s.e.m.) 2.5; mean weight 76.01+/-5.6 kg), eight post-menopausal females (mean age 59.9+/-2.0; mean weight 63.5+/-2.6 kg), and five males (mean age 35.8+/-8.8; mean weight 78.5+/-7.8 kg) undergoing elective or cosmetic surgery.

MEASUREMENTS

Cell viability and cell size were determined using staining techniques. RT-PCR was used to confirm the presence of aromatase. The regulation of aromatase activity was characterized using androstenedione as a substrate in a tritiated water release assay. Aromatase activity was analysed in abdominal subcutaneous stromal cells (ASC) and mature adipocytes (AD) cultured in serum-free medium with cortisol (10-6-10-7 M), insulin (500 nM) or a combination of both.

RESULTS

In ASC aromatase activity increased in females from 14.5+/-1.7 to 29. 3+/-2.6 pmol/mg/h (n=14, P<0.05) and to 25.2+/-2.1 pmol/mg/h with cortisol (10-7 M) and insulin, respectively (P<0.05). In males ASC basal aromatase activity (20.5+/-4.2 pmol/mg/h; n=5) was inhibited by cortisol (10-7 M) alone (12.3+/-1.8 pmol/mg/h) and in combination with insulin (6.6+/-1.2 pmol/mg/h; men vs women, P<0.005). Aromatase activity in mature adipocytes was stimulated by cortisol plus insulin (P<0.05) with no gender-specific differences. Treatment of ASC from both pre- and post-menopausal females with cortisol alone (10-6 M; 10-7 M) or in combination with insulin demonstrated significantly different aromatase regulation compared with male aromatase stromal cell regulation (P<0.05); however there were no differences in aromatase regulation between pre- and post-menopausal females either in stromal cells or adipocytes.

CONCLUSION

This study shows intrinsic gender differences in the regulation of aromatase, suggesting that differential enzyme regulation may affect sex steroid metabolism to alter the pattern of fat distribution between the sexes.

Molecular epidemiology of breast cancer: genetic variation in steroid hormone metabolism

The age-specific incidence rate of breast cancer in women rises until menopause, levels off and then rises again at a much lower rate indicating a possible hormonal influence on the disease risk. A large amount of evidence has implicated hormones and other compounds with oestrogen activity in the pathogenesis of certain endocrine cancers, particularly breast cancer. Widely dispersed hormone-like chemicals, capable of disrupting the endocrine system and interfering with proliferation, have been described. Compounds such as dioxins, some polychlorinated biphenyls and the plastic ingredient bisphenol-A have been shown to interfere with human reproduction and hormonal regulation. The levels of these foreign compounds as well as the levels of endogenous oestradiol may influence the risk of breast cancer. Endogenous oestradiol is synthesised in the ovarian theca cells of premenopausal women or in the stromal adipose cells of the breast of postmenopausal women and minor quantities in peripheral tissue. These cells, as well as breast cancer tissue, express all the necessary enzymes for this synthesis: CYP17, CYP11a, CYP19, hydroxysteroid hydrogenase, steroid sulphatase as well as enzymes further hydroxylating oestradiol such as CYP1A1, CYP3A4, CYP1B1. Polymorphisms in these enzymes may have a possible role in the link between environmental estrogens and hormone-like substances and the interindividual risk of breast cancer.

Progestin regulation of 11beta-hydroxysteroid dehydrogenase expression in T-47D human breast cancer cells

This study examined the enzymatic characteristics and steroid regulation of the glucocorticoid-metabolizing enzyme 11beta-hydroxysteroid dehydrogenase (11beta-HSD) in the human breast cancer cell line T-47D. In cell homogenates, exogenous NAD significantly increased the conversion of corticosterone to 11-dehydrocorticosterone, while NADP was ineffective. There was no conversion of 11-dehydrocorticosterone to corticosterone either with NADH or NADPH demonstrating the lack of reductase activity. In keeping with these results, RT-PCR analysis indicated a mRNA for 11beta-HSD2 in T-47D cells, while 11beta-HSD1 mRNA levels were undetectable. In T-47D cells treated for 24 h with medroxyprogesterone acetate (MPA), 11beta-HSD catalytic activity was elevated 11-fold, while estrone (E(1)), estradiol (E(2)) and the synthetic glucocorticoid dexamethasone (DEX) were ineffective. The antiprogestin mifepristone (RU486) acted as a pure antagonist of the progestin-enhanced 11beta-HSD activity, but did not exert any agonistic effects of its own. In addition, RT-PCR analysis demonstrated that MPA was a potent inducer of 11beta-HSD2 gene expression, increasing the steady-state levels of 11beta-HSD2 mRNA. Taken together, these results demonstrate that 11beta-HSD2 is the 11beta-HSD isoform expressed by T-47D cells under steady-state conditions and suggest the existence of a previously undocumented mechanism of action of progestins in breast cancer cells.

Insulin attenuates the stimulatory effects of tumor necrosis factor alpha on 11beta-hydroxysteroid dehydrogenase 1 in human adipose stromal cells

Obesity is frequently associated with insulin-resistance and abnormal glucose homeostasis. Recent evidence indicates that TNFalpha may play a role in mediating the insulin-resistance of obesity through its overexpression in adipose tissue. Previously, we have shown that human adipose stromal cells contain 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) mRNA and activity. The present study was designed to examine the effects of insulin on 11beta-HSD1 expression in human adipose stromal cells under basal and TNFalpha-stimulated conditions. The cells were obtained from breast adipose tissue by collagenase digestion, and grown to confluence under replicating conditions in 10% fetal bovine serum. The cells were transferred to serum-free medium for 24 h prior to treatment with either TNFalpha, insulin or both for a further 24 h. The level of 11beta-HSD1 reductase activity was determined by measuring the conversion of [(3)H]-cortisone to [(3)H]-cortisol at a substrate concentration of 10 nM. Treatment with TNFalpha at concentrations of 0.1-10 ng/ml resulted in a dose dependent increase in 11beta-HSD1 reductase activity from 1.5 to 10-fold. Insulin (0.1-100 nM) had no effect under basal conditions, but inhibited the stimulatory effects of TNFalpha (5 ng/ml) on 11beta-HSD1 reductase activity in a dose dependent fashion (8-66%) inhibition). Northern blot analysis revealed corresponding changes in the level of 11beta-HSD1 mRNA, suggesting that the effects of TNFalpha and insulin on 11beta-HSD1 activity are mediated at the level of gene transcription. The interaction between insulin and TNFalpha suggests that local and systemic factors may act in a concerted fashion to modulate glucocorticoid activity in adipose and other peripheral tissues.

An in vivo study of the cortisol-cortisone shuttle in subcutaneous abdominal adipose tissue

OBJECTIVE

Previous in vitro studies have demonstrated significant 11-beta hydroxysteroid dehydrogenase (11 beta-HSD) oxo-reductase activity in visceral, but not subcutaneous adipose stromal cells. We have conducted an in vivo study of the cortisol-cortisone shuttle in subcutaneous abdominal adipose tissue.

DESIGN

We measured arteriovenous (A-V) differences in serum cortisol and cortisone across subcutaneous abdominal adipose tissue and forearm muscle in a heterogeneous group of subjects.

PATIENTS

We studied 34 subjects (male:female = 12:22), age median (interquartile range) 45 (19-65) years, body mass index 32.7 (20.4-77.1) kg m-2, total body fat 34.4 (5.6-119.1) kg.

MEASUREMENTS

Serum cortisol and cortisone were measured in serum samples from a radial artery, superficial epigastric vein and deep forearm vein. Abdominal adipose and forearm blood flow rates were measured by 133Xenon washout and plethysmography, respectively.

RESULTS

For cortisone, there was significant (P < 0.001) clearance by adipose tissue, with an A-V difference of 4 (1-7) nmol/l. For cortisol there was a trend for arterial concentrations (203 (142-292) nmol/l) to be lower than venous (225 (152-263) nmol/l), but this was not significant. The adipose tissue cortisone clearance rate correlated with total body fat (r = 0.35, P = 0.05).

CONCLUSIONS

We have demonstrated 11 beta-HSD oxo-reductase activity in subcutaneous abdominal adipose tissue, which may be increased in obesity.

Differential regulation of 11 beta-hydroxysteroid dehydrogenase type 1 and 2 by nitric oxide in cultured human placental trophoblast and chorionic cell preparation

Two types of 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD) have been identified in different tissues. Type 1 has both oxidase and reductase activities interconverting cortisol and cortisone, whereas type 2 has only oxidase activity converting cortisol to cortisone. It has been proposed that placental 11 beta-HSD controls the passage of maternal glucocorticoids to the fetal circulation. However, little is known about the regulation of 11 beta-HSD in the human placenta and fetal membranes. We cultured human term placental trophoblast and chorionic trophoblast cells to examine effects of nitric oxide donors, sodium nitroprusside (SNP) and S-nitroso-N-acetyl penicillamine (SNAP), on the activity and messenger RNA (mRNA) expression of 11 beta-HSD. At 72 h of culture, placental trophoblast formed syncytial clumps that were cytokeratin positive and displayed mainly type 2 oxidase activity, although some type 1 reductase activity was detectable. Chorion preparations contain greater than 90% trophoblast cells as demonstrated by immunostaining for cytokeratin and less than 5% vimentin positive cells. Type 1 reductase activity predominated in the chorionic trophoblast cells with barely detectable type 1 or type 2 oxidase activity. Both SNP (1-400 microM) and SNAP (1 mM) inhibited placental 11 beta-HSD type 2 oxidase activity but not type 1 reductase activity either in placental or chorionic cells. An inhibitory effect on type 2 oxidase activity was reproduced in part by 8-bromo cGMP, blocked partially by the guanylate cyclase inhibitor LY83583 (1 microM), but not by an ADP-ribosylation inhibitor N, N'-hexamethylene-bis-acetamide (HMBG) (10 mM). SNP also suppressed the expression of type 2 mRNA in cultured placental trophoblast in a dose-dependent manner, and this effect was also blocked by LY83583. We conclude that human placental trophoblast possesses predominantly 11 beta-HSD type 2 oxidase activity, whereas chorionic cells possess mainly type 1 reductase activity under the culture conditions employed. Nitric oxide specifically attenuated 11 beta-HSD type 2 oxidase activity as well as its mRNA expression in the placental trophoblast. The effect was mediated at least partially through the cGMP pathway, although an alternative pathway other than ADP-ribosylation may exist.