11beta-Hydroxysteroid dehydrogenase type 1-driven cortisone reactivation regulates plasminogen activator inhibitor type 1 in adipose tissue of obese women

Adipokines and cardiovascular risk in Cushing's syndrome

Cushing's syndrome (CS) is associated with increased cardiovascular morbidity and mortality. Recent evidence also suggests that increased cardiovascular risk may persist even after long-term remission of CS. Increased central obesity, a typical feature of CS, is associated with altered production of adipokines, which contributes to the pathogenesis of several metabolic and cardiovascular complications observed in this condition. In vitro and in vivo studies have shown a relationship between cortisol and adipokines in several experimental settings. In patients with either active or 'cured' CS, an increase in leptin and resistin levels as well as the release of pro-inflammatory cytokines, such as tumor necrosis factor-α and interleukin-6, may be associated with increased cardiovascular risk. For other adipokines, including adiponectin, results are inconclusive. Studies are needed to further elucidate the interactions between clinical and subclinical increases in cortisol production and altered adipokine release in CS.

11-Hydroxy-β-steroid dehydrogenase gene expression in canine adipose tissue and adipocytes: stimulation by lipopolysaccharide and tumor necrosis factor α

The enzyme 11β-hydroxysteroid dehydrogenase 1 (11β-HSD-1) is expressed in a number of tissues in rodents and humans and is responsible for the reactivation of inert cortisone into cortisol. Its gene expression and activity are increased in white adipose tissue (WAT) from obese humans and may contribute to the adverse metabolic consequences of obesity and the metabolic syndrome. The extent to which 11β-HSD-1 contributes to adipose tissue function in dogs is unknown; the aim of the present study was to examine 11β-HSD-1 gene expression and its regulation by proinflammatory and anti-inflammatory agents in canine adipocytes. Real-time PCR was used to examine the expression of 11β-HSD-1 in canine adipose tissue and canine adipocytes differentiated in culture. The mRNA encoding 11β-HSD-1 was identified in all the major WAT depots in dogs and also in liver, kidney, and spleen. Quantification by real-time PCR showed that 11β-HSD-1 mRNA was least in perirenal and falciform depots and greatest in subcutaneous, omental, and gonadal depots. Greater expression was seen in the omental depot in female than in male dogs (P=0.05). Gene expression for 11β-HSD-1 was also seen in adipocytes, from both subcutaneous and visceral depots, differentiated in culture; expression was evident throughout differentiation but was generally greatest in preadipocytes and during early differentiation, declining as cells progressed to maturity. The inflammatory mediators lipopolysaccharide and tumor necrosis factor α had a main stimulatory effect on 11β-HSD-1 gene expression in canine subcutaneous adipocytes, but IL-6 had no significant effect. Treatment with dexamethasone resulted in a significant time- and dose-dependent increase in 11β-HSD-1 gene expression, with greatest effects seen at 24 h (2 nM: approximately 4-fold; 20 nM: approximately 14-fold; P=0.010 for both). When subcutaneous adipocytes were treated with the peroxisome proliferator activated receptor γ agonist rosiglitazone, similar dose- and time-dependent effects were noted. However, no effects were seen when adipocytes from the gonadal WAT depot were treated with rosiglitazone. The induction of 11β-HSD-1 expression, by the pro-inflammatory cytokine tumor necrosis factor α and by lipopolysaccharide may have implications for the pathogenesis of obesity and its associated diseases in the dog.

Direct fibrogenic effects of aldosterone on normotensive kidney: an effect modified by 11β-HSD activity

Aldosterone (Aldo) can be a profibrotic factor in cardiovascular and renal tissues. This study tests the hypothesis that prolonged Aldo exposure is able to directly induce fibrotic changes in the kidney of a normal nonhypertensive animal. Immortalized rat proximal tubule cells (IRPTC) containing 11β-hydroxysteroid dehydrogenase (11β-HSD1) but no mineralocorticoid receptors (MR) and mouse inner medullary collecting duct cells (IMCD) containing 11β-HSD2 and MR were examined. IRPTC exposed to Aldo or corticosterone (10 nM) for 48 h demonstrated no change in collagen production as assessed by Sirius red staining. In contrast, IMCD treated with Aldo exhibited a marked increase in the expression of collagen, fibronectin, and connective tissue growth factor (CTGF), whereas corticosterone alone had no effect. The Aldo-induced overexperession of collagen, fibronectin, and CTGF was substantially attenuated by the MR antagonist RU-318 and by the 11β-HSD end product 11-dehydrocorticosterone, but not by the glucocorticoid receptor antagonist RU-486. In vivo, early fibrotic changes with elevated collagen, fibronectin, and CTGF expression were observed in kidneys isolated from normotensive adrenalectomized mice receiving a continuous infusion of Aldo (8 μg·kg(-1)·day(-1)) for 1 wk. These changes were not present in corticosterone-treated mice. Aldo-induced changes were attenuated in adrenally intact mice and in mice treated with RU-318 or 11-dehydrocorticosterone. Thus, extended Aldo exposure produces fibrotic changes in cells containing MR and in normal kidneys. MR antagonists and the end products of 11β-HSD attenuate these fibrogenic effects.

Secretory type II phospholipase A2 is produced and secreted by epicardial adipose tissue and overexpressed in patients with coronary artery disease

CONTEXT

Epicardial adipose tissue (EAT) is a visceral adipose tissue in close contact with coronary vessels, the excess of which is associated with coronary artery disease (CAD).

OBJECTIVE

Our goal was to identify candidate molecule(s) characterizing EAT that could intervene in the pathogenesis of CAD.

DESIGN

An approach combining microarrays and bioinformatic sequence analysis tools for predicting secreted proteins (TargetP) was applied to paired biopsies of sc adipose tissue (SAT) and EAT, obtained from patients with or without CAD (NCAD). RESULTS were validated in three independent groups of subjects by quantitative RT-PCR, Western blot, immunohistochemistry, and explant secretion.

RESULTS

Secretory type II phospholipase A2 (sPLA2-IIA) ranked as the highest gene coding for potentially secreted proteins with the highest overexpression in EAT in both CAD and NCAD. Quantitative RT-PCR confirmed its increased expression in EAT (P < 0.01) as well as EAT from CAD as compared with NCAD (49.3 +/- 13 vs. 17.4 +/- 9.7 P < 0.01). sPLA2-IIA protein levels were higher in EAT than SAT (P < 0.001). EAT explants also showed significantly higher sPLA2-IIA secretion levels than SAT ones (4.37 +/- 2.7 vs. 0.67 +/- 0.28 ng/ml to 1 per gram tissue per 24 h, P < 0.03). sPLA2-IIA labeling was seen in the stroma vascular fraction between adipocytes and in connective capsules in EAT, with no immunostaining of the adipocytes. SAT was weakly labeled following the same process.

CONCLUSION

We have shown for the first time an increased expression of sPLA2-IIA in EAT in patients with CAD. sPLA2-IIA is a phospholipase, which has been shown to be an independent risk factor for CAD. These findings suggest that EAT has a potentially pathophysiological role in CAD.

Phenylcyclobutyl triazoles as selective inhibitors of 11beta-hydroxysteroid dehydrogenase type I

3-(Phenylcyclobutyl)-1,2,4-triazoles were identified as selective inhibitors of 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1). These were active both in vitro and in an in vivo mouse pharmacodynamic (PD) model. Fluorine substitution of the cyclobutane ring improved the pharmacokinetic profile significantly. The synthesis and structure-activity relationships are presented.

4-Methyl-5-phenyl triazoles as selective inhibitors of 11beta-hydroxysteroid dehydrogenase type I

4-Methyl-5-phenyl-(1,2,4)-triazoles were identified as selective inhibitors of 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1). They were active in vitro and in an in vivo mouse pharmacodynamic (PD) model. The synthesis and structure activity relationships are presented.

Postnatal programming of glucocorticoid metabolism in rats modulates high-fat diet-induced regulation of visceral adipose tissue glucocorticoid exposure and sensitivity and adiponectin and proinflammatory adipokines gene expression in adulthood

OBJECTIVE

Alterations of the perinatal environment, which lead to increased prevalence of the metabolic syndrome in adulthood, program an upregulation of systemic and/or adipose tissue glucocorticoid metabolism (11 beta-hydroxysteroid dehydrogenase type 1 [11 beta-HSD-1]-induced corticosterone reactivation). We hypothesized that postnatal programming could modulate high-fat diet-induced adipose tissue dysregulation in adulthood.

RESEARCH DESIGN AND METHODS

We compared the effects of chronic (since weaning) high- or low-fat diet in postnatally normofed (control) or overfed (programmed) rats.

RESULTS

Postnatal programming accentuated high-fat diet-induced overweight, insulin resistance, glucose intolerance, and decrease in circulating and epididymal adipose tissue adiponectin. Neither manipulation altered liver function. Postnatal programming or high-fat diet increased systemic corticosterone production, which was not further modified when both manipulations were associated. Postnatal programming suppressed high-fat diet-induced decrease in mesenteric adipose tissue (MAT) glucocorticoid sensitivity and triggered high-fat diet-induced increase in MAT glucocorticoid exposure, subsequent to enhanced MAT 11 beta-HSD-1 gene expression. MAT tumor necrosis factor (TNF)-alpha, TNF-receptor 1, interleukin (IL)-6, resistin, and plasminogen activator inhibitor-1 mRNAs were not changed by high-fat feeding in control rats and showed a large increase in programmed animals, with this effect further enhanced by high-fat diet for TNF-alpha and IL-6.

CONCLUSIONS

Our data show for the first time that postnatal manipulation programs high-fat diet-induced upregulation of MAT glucocorticoid exposure, sensitivity, and inflammatory status and therefore reveal the pivotal role of the environment during the perinatal period on the development of diet-induced adipose tissue dysregulation in adulthood. They also urge the need for clinical trials with specific 11 beta-HSD-1 inhibitors.

Effect of sleep apnea syndrome on the circadian profile of cortisol in obese men

It has been hypothesized that sleep apnea syndrome (SAS) increases hypothalamic-pituitary-adrenal axis activity and, through increased cortisol levels, participates in the pathophysiology of metabolic and cardiovascular complications. We compared the circadian profiles of cortisol in obese men with [obSAS+; apnea-hypopnea index (AHI) >or= 20/h] and without SAS (obSAS-; AHI <or= 5/h). 1) Salivary cortisol (5 samples: before/30 min after dinner, 2100, upon/30 min after awakening) was measured in 15 obSAS+, 19 obSAS-, and 19 normal-weight controls (NWC). 2) Plasma cortisol (every 30 min for 24 h under highly controlled conditions and portable EEG device) was measured in 9 obSAS+, 8 obSAS-, and 10 NWC men. Visceral adipose tissue surface was measured by CT scan. In both studies, obSAS+ and obSAS- men were comparable for age, BMI, waist circumference, and waist-to-hip ratio. First, no difference was found, using ANOVA for repeated measures, between obSAS+ and obSAS- subjects for any salivary cortisol measurement. No correlation was found between salivary cortisol and AHI or nocturnal SaO(2). Similarly, obSAS+ and obSAS- men showed no difference in plasma cortisol rhythmicity: 24-h minimum, maximum, and mean, ANOVA for repeated measures, mathematical modeling of cortisol rhythm (COSINOR), and morning secretory peak. Conversely, ANOVA for repeated measures showed decreased cortisol levels in obese vs. NWC men during both the trough (2200-0130) and the peak (0600-0900) independently of SAS status. We show that SAS per se is not associated with any change of the level or of the features of salivary and plasma cortisol rhythmicity and confirm that men with visceral obesity display lower plasma cortisol levels than NWC men.

Plasminogen activator inhibitor-1, adipose tissue and insulin resistance

PURPOSE OF REVIEW

Plasminogen activator inhibitor (PAI)-1 is a physiological inhibitor of plasminogen activators (urokinase and tissue types) and vitronectin. It is synthesized by adipose tissue, and its levels in plasma are increased in obesity and reduced with weight loss. Circulating PAI-1 level predicts development of type 2 diabetes, suggesting that it may be causally related to development of obesity. A role for PAI-1 in development of obesity has only partially been established, however. This review summarizes current knowledge, gives context to developments thus far and discusses controversies.

RECENT FINDINGS

In addition to its role in atherothrombosis, PAI-1 might be involved in adipose tissue development. PAI-1 is produced by ectopic fat depots under the influence of inducers. Among the most recently described inducers are inflammation, oxidative stress and circadian clock protein. PAI-1 may play several roles in contributing to obesity: through indirect effects on insulin signalling, by influencing adipocyte differentiation and by regulating recruitment of inflammatory cells within adipose tissue.

SUMMARY

These recent findings emphasize the involvement of PAI-1 in controlling the biology of adipose tissue; PAI-1 is an attractive new therapeutic target to retard the metabolic complications that accompany obesity.

Biomarkers of obesity and subsequent cardiovascular events

Obesity is a major risk factor for cardiovascular diseases, but the mechanisms for increased cardiovascular risk in obesity are still unclear. Inflammation and increased oxidative stress are two potential mechanisms proposed to play a major role in the morbidity associated with obesity. Studies that investigate these mechanisms rely on biomarkers, but validated biomarkers for obesity-related cardiovascular outcomes are lacking. By finding optimal biomarkers, diagnostic criteria for cardiovascular diseases can be refined in the obese beyond "traditional" risk factors to identify early pathologic processes. The objective of this review is to identify potential early biomarkers resulting from obesity and associated with cardiovascular disease. Studies were initially identified through the search engine PubMed by using the keywords "obesity" and "biomarker." Subsequently, combinations of the keywords "obesity," "biomarker," "cardiovascular risk," "adipose tissue," "adipokine," "adipocytokine," and "oxidative stress" were used. The SOURCE database and Online Mendelian Inheritance in Man (OMIM) were used to obtain more information on the biomarkers. Results of the searches yielded a large number of potential biomarkers that occur in obesity and which either correlate with traditional cardiovascular risk factors or predict subsequent cardiovascular events. Several biomarkers are promising regarding their biologic properties, but they require further validation in humans.

PAI-1 and the Metabolic Syndrome

The link between plasminogen activator inhibitor (PAI)-1 and the metabolic syndrome with obesity was established many years ago. Increased PAI-1 level can be now considered a true component of the syndrome. The metabolic syndrome is associated with an increased risk of developing cardiovascular disease, and PAI-1 overexpression may participate in this process. The mechanisms of PAI-1 overexpression during obesity are complex, and it is conceivable that several inducers are involved at the same time at several sites of synthesis. Interestingly, recent in vitro and in vivo studies showed that besides its role in atherothrombosis, PAI-1 is also implicated in adipose tissue development and in the control of insulin signaling in adipocytes. These findings suggest PAI-1 inhibitors serve in the control of atherothrombosis and insulin resistance.