Enhanced 11beta-hydroxysteroid dehydrogenase activity, the metabolic syndrome, and systemic hypertension

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

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

A urinary metabolomics study of a Polish subpopulation environmentally exposed to arsenic

BACKGROUND

Almost every organ in the human body can be affected by arsenic (As) exposure associated with various industrial processes, as well as with contaminated food, drinking water and polluted air. Much is known about high exposure to inorganic As but there is little data on the metabolic changes connected to a low exposure e.g. in people living in smelter areas.

OBJECTIVES

The objectives of the study were: (1) characterise urinary concentration of total arsenic (AsT) in Polish inhabitants of the vicinity of a copper smelter area, (2) speciation analysis of various forms of arsenic in girls (GL), boys (BL), women (WL) and men (ML) with a slightly elevated AsT concentration and age/sex matched groups with a substantially higher AsT concentration, (GH, BH, WH and MH - respectively), (3) comparison of metabolomics profiles of urine between the age/sex matched people with low and high AsT concentrations.

METHODS

Urine samples were analysed for total arsenic and its chemical forms (As^III; As^V, methylarsonic acid, dimethylarsinic acid, arsenobetaine) using HPLC-ICP-MS. Untargeted metabolomics analysis of the urine samples was performed using UPLC system connected to Q-TOF-MS equipped with an electrospray source. The XCMS Online program was applied for feature detection, retention time correction, alignment, statistics, annotation and identification. Potentially identified compounds were fragmented and resulting spectra were compared to the spectra in the Human Metabolome Database.

RESULTS

Urine concentration of AsT was, as follows: GL 16.40 ± 0.83; GH 115.23 ± 50.52; BL 16.48 ± 0.83; BH 95.00 ± 50.03; WL 16.93 ± 1.21; WH 170.13 ± 96.47; ML 16.91 ± 1.20; MH 151.71 ± 84.31 μg/l and percentage of arsenobetaine in AsT was, as follows: GL 65.5 ± 13.8%, GH 87.2 ± 4.7%, BL 59.8 ± 12.5%, BH 90.5 ± 2.4%, WL 50.8 ± 14.1%, WH 90.4 ± 3.5%, ML 53.3 ± 10.0%, MH 74.6 ± 20.2%. In the people with low and high AsT concentrations there were significant differences in the intensity of signal (is.) from numerous compounds being metabolites of neurotransmitters, nicotine and hormones transformation (serotonin in the girls and women; catecholamines in the girls, boys and women; mineralocorticoids and glucocorticoids in the boys, androgens in the women and men and nicotine in the boys, women and men). These changes might have been associated with higher is. from metabolites of leucine, tryptophan, purine degradation (in the GH, WH), urea cycle (in the WH and MH), glycolysis (in the WH) and with lower is. from metabolites of tricarboxylic acid cycle (in the BH) in comparison with low AsT matched groups. In the MH vs. ML higher is. from metabolite of lipid peroxidation (4-hydroxy-2-nonenal) was observed. Additionally, the presence of significant differences was reported in is. from food components metabolites, which might have modulated the negative effects of As (vitamin C in the girls, boys and men, vitamin B₆ in the girls, boys and women as well as phenolic compounds in the boys and girls). We hypothesize that the observed higher is. from metabolites of sulphate (in MH) and glucoronate degradation (in BH, WH and MH) than in the matched low AsT groups may be related to the impaired glucuronidation and sulfonation and higher is. from catecholamines, nicotine and hormones.

CONCLUSION

Our results indicated that even a low exposure to As is associated with metabolic changes and that urine metabolomics studies could be a good tool to reflect their wide spectrum connected to specific environmental exposure to As, e.g. in smelter areas.

A new cryptic host defense peptide identified in human 11-hydroxysteroid dehydrogenase-1 β-like: from in silico identification to experimental evidence

BACKGROUND

Host defence peptides (HDPs) are evolutionarily conserved components of innate immunity. Human HDPs, produced by a variety of immune cells of hematopoietic and epithelial origin, are generally grouped into two families: beta structured defensins and variably-structured cathelicidins. We report the characterization of a very promising cryptic human HDP, here called GVF27, identified in 11-hydroxysteroid dehydrogenase-1 β-like protein.

METHODS

Conformational analysis of GVF27 and its propensity to bind endotoxins were performed by NMR, Circular Dichroism, Fluorescence and Dynamic Light Scattering experiments. Crystal violet and WST-1 assays, ATP leakage measurement and colony counting procedures were used to investigate antimicrobial, anti-biofilm, cytotoxicity and hemolytic activities. Anti-inflammatory properties were evaluated by ELISA.

RESULTS

GVF27 possesses significant antibacterial properties on planktonic cells and sessile bacteria forming biofilm, as well as promising dose dependent abilities to inhibit attachment or eradicate existing mature biofilm. It is unstructured in aqueous buffer, whereas it tends to assume a helical conformation in mimic membrane environments as well as it is able to bind lipopolysaccharide (LPS) and lipoteichoic acid (LTA). Notably it is not toxic towards human and murine cell lines and triggers a significant innate immune response by attenuating expression levels of pro-inflammatory interleukins and release of nitric oxide in LPS induced macrophages.

CONCLUSION

Human GVF27 may offer significant advantages as leads for the design of human-specific therapeutics.

GENERAL SIGNIFICANCE

Human cryptic host defence peptides are naturally no immunogenic and for this they are a real alternative for solving the lack of effective antibiotics to control bacterial infections.

Spironolactone reduces cardiovascular and cerebrovascular morbidity and mortality in hemodialysis patients

OBJECTIVES

This study sought to assess whether spironolactone treatment reduces the high incidence of cardiovascular and cerebrovascular (CCV) morbidity and mortality in hemodialysis (HD) patients.

BACKGROUND

Aldosterone receptor blockers reduce cardiac-related events, but the efficacy of the agents in HD patients is unclear.

METHODS

A 3-year randomized trial involving 5 clinics was performed. Of the 309 oligoanuric HD patients enrolled in the study, 157 patients were randomly assigned to receive 25 mg/day of spironolactone without any restriction on dietary potassium intake (treatment group), and 152 patients were assigned to a control group. The primary outcome was a composite of death from CCV events or hospitalization for CCV events, and the secondary outcome was death from all causes.

RESULTS

During the 3-year follow-up, the primary outcome occurred in 5.7% of patients in the treatment group and in 12.5% of patients in the control group. Hazard ratios (HRs) for the primary outcome for treatment were 0.404 (95% confidence interval [CI]: 0.202 to 0.809; p = 0.017) and 0.379 (95% CI: 0.173 to 0.832; p = 0.016) before and after adjustment, respectively. The secondary outcome was significantly reduced in the treatment group compared with the control group (6.4% vs. 19.7%; HRs: 0.355 [95% CI: 0.191 to 0.662; p = 0.002] and 0.335 [95% CI: 0.162 to 0.693; p = 0.003] before and after adjustment, respectively). Gynecomastia or breast pain was reported in 16 patients (10.2%) in the treatment group. Serious hyperkalemia led to treatment discontinuation in 3 patients (1.9%).

CONCLUSIONS

Aldosterone receptor blockade using spironolactone may substantially reduce the risk of both CCV morbidity and death among HD patients; however, larger-scale studies are recommended to further confirm its efficacy. (Effects of Spironolactone on Cardio- and Cerebrovascular Morbidity and Mortality in Hemodialysis Patients; NCT01687699).

Obesity pharmacotherapy: current perspectives and future directions

The rising tide of obesity and its related disorders is one of the most pressing health concerns worldwide, yet existing medicines to combat the problem are disappointingly limited in number and effectiveness. Recent advances in mechanistic insights into the neuroendocrine regulation of body weight have revealed an expanding list of molecular targets for novel, rationally designed antiobesity pharmaceutical agents. Antiobesity drugs act via any of four mechanisms: 1) decreasing energy intake, 2) increasing energy expenditure or modulating lipid metabolism, 3) modulating fat stores or adipocyte differentiation, and 4) mimicking caloric restriction. Various novel drug candidates and targets directed against obesity are currently being explored. A few of them are also in the later phases of clinical trials. This review discusses the development of novel antiobesity drugs based on current understanding of energy homeostasis

High-end normal adrenocorticotropic hormone and cortisol levels are associated with specific cardiovascular risk factors in pediatric obesity: a cross-sectional study

BACKGROUND

The hypothalamic-pituitary-adrenal (HPA) axis, and in particular cortisol, has been reported to be involved in obesity-associated metabolic disturbances in adults and in selected populations of adolescents. The aim of this study was to investigate the association between morning adrenocorticotropic hormone (ACTH) and cortisol levels and cardiovascular risk factors in overweight or obese Caucasian children and adolescents.

METHODS

This cross-sectional study of 450 obese children and adolescents (aged 4 to 18 years) was performed in a tertiary referral center. ACTH, cortisol, cardiovascular risk factors (fasting and post-challenge glucose, high-density lipoprotein (HDL)-cholesterol, low-density lipoprotein (LDL)-cholesterol, triglycerides, and hypertension) and insulin resistance were evaluated. All analyses were corrected for confounding factors (sex, age, puberty, body mass index), and odds ratios were determined.

RESULTS

ACTH and cortisol levels were positively associated with systolic and diastolic blood pressure, triglycerides, fasting glucose and insulin resistance. Cortisol, but not ACTH, was also positively associated with LDL-cholesterol. When adjusted for confounding factors, an association between ACTH and 2 h post-oral glucose tolerance test glucose was revealed. After stratification according to cardiovascular risk factors and adjustment for possible confounding factors, ACTH levels were significantly higher in subjects with triglycerides ≥90th percentile (P <0.02) and impaired fasting glucose or glucose tolerance (P <0.001). Higher cortisol levels were found in subjects with blood pressure ≥95th percentile and LDL-cholesterol ≥90th percentile. Overall, the highest tertiles of ACTH (>5.92 pmol/l) and cortisol (>383.5 nmol/l) although within the normal range were associated with increases in cardiovascular risk factors in this population.

CONCLUSIONS

In obese children and adolescents, high morning ACTH and cortisol levels are associated with cardiovascular risk factors. High ACTH levels are associated with high triglyceride levels and hyperglycemia, while high cortisol is associated with hypertension and high LDL-cholesterol. These specific relationships suggest complex mechanisms through which the HPA axis may contribute to metabolic impairments in obesity, and merit further investigations.

Hypertension in obesity

Obesity and HTN are on the rise in the world. HTN seems to be the most common obesity-related health problem and visceral obesity seems to be the major culprit. Unfortunately, only 31% of hypertensives are treated to goal. This translates into an increased incidence of CVD and related morbidity and mortality. Several mechanisms have been postulated as the causes of obesity-related HTN. Activation of the RAAS, SNS, insulin resistance, leptin, adiponectin, dysfunctional fat, FFA, resistin, 11 Beta dehydrogenase, renal structural and hemodynamic changes, and OSA are some of the abnormalities in obesity-related HTN. Many of these factors are interrelated. Treatment of obesity should begin with weight loss via lifestyle modifications, medications, or bariatric surgery. According to the mechanisms of obesity-related HTN, it seems that drugs that blockade the RAAS and target the SNS should be ideal for treatment. There is not much evidence in the literature that one drug is better than another in controlling obesity-related HTN. There have only been a few studies specifically targeting the obese hypertensive patient, but recent trials that emphasize the importance of BP control have enrolled both overweight and obese subjects. Until we have further studies with more in-depth information about the mechanisms of obesity-related HTN and what the targeted treatment should be, the most important factor necessary to control the obesity-related HTN pandemic and its CVD and CKD consequences is to prevent and treat obesity and to treat HTN to goal.

The role of salt in the pathogenesis of fructose-induced hypertension

Metabolic syndrome, as manifested by visceral obesity, hypertension, insulin resistance, and dyslipidemia, is reaching epidemic proportions in the Western World, specifically the United States. Epidemiologic studies suggest that the increased prevalence of metabolic syndrome directly correlates with an increase in the consumption of fructose, mainly in the form of high-fructose corn syrup. This inexpensive alternative to traditional sugar has been increasingly utilized by the food industry as a sweetener since the 1960s. While augmented caloric intake and sedentary lifestyles play important roles in the increasing prevalence of obesity, the pathogenesis of hypertension in metabolic syndrome remains controversial. One intriguing observation points to the role of salt in fructose-induced hypertension. Recent studies in rodents demonstrate that increased dietary fructose intake stimulates salt absorption in the small intestine and kidney tubules, resulting in a state of salt overload, thus setting in motion a cascade of events that will lead to hypertension. These studies point to a novel interaction between the fructose-absorbing transporter, Glut5, and the salt transporters, NHE3 and PAT1, in the intestine and kidney proximal tubule. This paper will focus on synergistic roles of fructose and salt in the pathogenesis of hypertension resulting from salt overload.

Dietary fructose, salt absorption and hypertension in metabolic syndrome: towards a new paradigm

The worldwide increase in the incidence of metabolic syndrome correlates with marked increase in total fructose intake in the form of high-fructose corn syrup, beverage and table sugar. Increased dietary fructose intake in rodents has been shown to recapitulate many aspects of metabolic syndrome by causing hypertension, insulin resistance and hyperlipidaemia. Recent studies demonstrated that increased dietary fructose intake stimulates salt absorption in the small intestine and kidney tubules, resulting in a state of salt overload and thus causing hypertension. The absorption of salt (sodium and chloride) in the small intestine is predominantly mediated via the chloride/base exchangers DRA (Down Regulated in Adenoma) (SLC26A3) and PAT1 (Putative Anion Transporter 1) (SLC26A6), and the Na(+) /H(+) exchanger NHE3 (Sodium Hydrogen Exchanger3) (SLC9A3). PAT1 and NHE3 also co-localize on the apical membrane of kidney proximal tubule. Luminal fructose stimulated salt absorption in the jejunum and kidney tubules, responses that were significantly diminished in PAT1 null mice. These studies further demonstrated that Glut5 (SLC2A5) is the major fructose-absorbing transporter in the small intestine (and kidney proximal tubule) and plays an essential role in the systemic homeostasis of fructose. Increased dietary fructose intake for several weeks upregulated the expression of NHE3, PAT1 and Glut5 in the intestine and resulted in hypertension in wild-type mice, a response that was almost abolished in PAT1 null mice and abrogated in Glut5 null mice. This article will discuss the interaction of Glut5 with salt-absorbing transporters and review the role of dietary fructose in enhanced salt absorption in intestine and kidney as it relates to the pathogenesis of hypertension in metabolic syndrome.

Hypothalamic-pituitary-adrenal axis abnormalities in response to deletion of 11beta-HSD1 is strain-dependent

Inter-individual differences in hypothalamic-pituitary-adrenal (HPA) axis activity underlie differential vulnerability to neuropsychiatric and metabolic disorders, although the basis of this variation is poorly understood. 11beta-Hydroxysteroid dehydrogenase type 1 (11beta-HSD1) has previously been shown to influence HPA axis activity. 129/MF1 mice null for 11beta-HSD1 (129/MF1 HSD1(-/-)) have greatly increased adrenal gland size and altered HPA activity, consistent with reduced glucocorticoid negative feedback. On this background, concentrations of plasma corticosterone and adrenocorticotrophic hormone (ACTH) were elevated in unstressed mice, and showed a delayed return to baseline after stress in HSD1-null mice with reduced sensitivity to exogenous glucocorticoid feedback compared to same-background genetic controls. In the present study, we report that the genetic background can dramatically alter this pattern. By contrast to HSD1(-/-) mice on a 129/MF1 background, HSD1(-/-) mice congenic on a C57Bl/6J background have normal basal plasma corticosterone and ACTH concentrations and exhibit normal return to baseline of plasma corticosterone and ACTH concentrations after stress. Furthermore, in contrast to 129/MF1 HSD1(-/-) mice, C57Bl/6J HSD1(-/-) mice have increased glucocorticoid receptor expression in areas of the brain involved in glucocorticoid negative feedback (hippocampus and paraventricular nucleus), suggesting this may be a compensatory response to normalise feedback control of the HPA axis. In support of this hypothesis, C57Bl/6J HSD1(-/-) mice show increased sensitivity to dexamethasone-mediated suppression of peak corticosterone. Thus, although 11beta-HSD1 appears to contribute to regulation of the HPA axis, the genetic background is crucial in governing the response to (and hence the consequences of) its loss. Similar variations in plasticity may underpin inter-individual differences in vulnerability to disorders associated with HPA axis dysregulation. They also indicate that 11beta-HSD1 inhibition does not inevitably activate the HPA axis.

Adipose tissue 11-beta-Hydroxysteroid Dehydrogenase Type 1 and Hexose-6-Phosphate Dehydrogenase gene expressions are increased in patients with type 2 diabetes mellitus

AIMS

We have determined 11-beta-Hydroxysteroid Dehydrogenase Type 1 (HSD11B1) and Hexose-6-Phosphate Dehydrogenase (H6PD) mRNA expression levels in adipose tissues from patients with type 2 diabetes mellitus.

METHODS

Six non-diabetic and seven diabetic male patients who undergo elective abdominal surgery were included in the study and visceral and subcutaneous adipose tissue samples were obtained. Fresh preadipocyte cultures were administered to low and high glucose medium (11M and 25M) in vitro for 24h and mRNA extractions were performed. HSD11B1 and H6PD gene mRNA expression levels were determined by real-time PCR and compared. Glyceraldehyde-3-phosphate Dehydrogenase (G3PD) mRNA level is used as housekeeping gene expression.

RESULTS

HSD11B1 mRNA levels were significantly higher in patient with T2DM than controls in both visceral and subcutaneous adipose tissues (3.35+/-0.7 vs. 0.37+/-0.1; P=0.01 and 2.07+/-0.8 vs. 0.11+/-0.05; P=0.01, respectively). H6PD mRNA levels were also significantly higher in patient with T2DM than controls in both visceral and subcutaneous adipose tissues (3.95+/-1.2 vs. 1.95+/-0.8; P=0.050 and 2.23+/-1.1 vs. 0.46+/-0.1; P=0.043, respectively).

CONCLUSIONS

Failure to down-regulate HSD11B1 activity in patients with type 2 diabetes may contribute to the pathogenesis of T2DM. Subcutaneous and visceral adipose tissues similarly exhibit the same variation in patients with type 2 diabetes mellitus.

Hypertension in obesity

Hypertension and obesity are major components of the cardiometabolic syndrome and are both on the rise worldwide, with enormous consequences on global health and the economy. The relationship between hypertension and obesity is multifaceted; the etiology is complex and it is not well elucidated. This article, reviews the current knowledge on obesity-related hypertension. Further understanding of the underlying mechanisms of this epidemic will be important in devising future treatment avenues.

Association between the metabolic syndrome and serum cortisol in overweight Latino youth

OBJECTIVE

The purpose of this report is to investigate the associations between metabolic syndrome (MS) and levels of morning serum cortisol in a cohort of overweight Latino youth.

DESIGN

Subjects were 205 overweight, Latino youth (age 8-13 yr, body mass index percentile > 85, family history positive for type 2 diabetes). Measures included body composition by dual-energy x-ray absorptiometry, intraabdominal adipose tissue (IAAT) by magnetic resonance imaging, insulin sensitivity by frequently sampled iv glucose tolerance test/minimal model, fasting lipids, and serum cortisol.

RESULTS

Children with MS had higher body mass index percentile, total body fat mass, and IAAT and lower insulin sensitivity than those without MS. Children with MS had higher morning serum cortisol levels, whether unadjusted (10.1 +/- 3.7 vs. 9.0 +/- 2.8 microg/dl, P < 0.05) or after adjusting for age, gender, total body fat and lean tissue mass, and insulin sensitivity (10.4 +/- 0.4 vs. 8.9 +/- 0.3 microg/dl, P < 0.01). Increasing number of features of MS was associated with higher cortisol levels, after adjusting for covariates (P = 0.001). Among individual features of MS, systolic blood pressure had the strongest relationship with adjusted cortisol level (r = 0.34; P < 0.001), followed by diastolic blood pressure and fasting plasma glucose (both r = 0.23; P < 0.01). IAAT was associated with cortisol (r = 0.16; P < 0.05), whereas high-density lipoprotein, triglycerides, and waist circumference were not.

CONCLUSIONS

In overweight, Latino youth, MS is associated with higher morning serum cortisol levels, independent of body fat and insulin sensitivity. More studies are needed to investigate the role of relative hypercortisolism and chronic stress in obesity-related metabolic disorders in children.

Adrenocortical dysregulation as a major player in insulin resistance and onset of obesity

The aim of this review is to explore the dysregulation of adrenocortical secretions as a major contributor in the development of obesity and insulin resistance. Disturbance of adipose tissue physiology is one of the primary events in the development of pathologies associated with the metabolic syndrome, such as obesity and type 2 diabetes. Several studies indicate that alterations in metabolism of glucocorticoids (GC) and androgens, as well as aldosterone in excess, are involved in the emergence of metabolic syndrome. Cross talk among adipose tissue, the hypothalamo-pituitary complex, and adrenal gland activity plays a major role in the control of food intake, glucose metabolism, lipid storage, and energy balance. Perturbation of this cross talk induces alterations in the regulatory mechanisms of adrenocortical steroid synthesis, secretion, degradation, and/or recycling, at the level of the zonae glomerulosa (aldosterone), fasciculata (GC and GC metabolites), and reticularis (androgens and androgen precursors DHEA and DHEAS). As a whole, these adrenocortical perturbations contribute to the development of metabolic syndrome at both the paracrine and systemic level by favoring the physiological dysregulation of organs responsive to aldosterone, GC, and/or androgens, including adipose tissue.

Key reports from the 9th International Workshop on Adverse Drug Reactions and Lipodystrophy in HIV 2007

The 9th International Workshop on Adverse Drug Reactions and Lipodystrophy in HIV provided a forum for the presentation of basic and clinical research focused on the pathogenesis and management of lipodystrophy and other adverse events associated with antiretroviral therapy. New data were reported on the contribution of both antiretroviral therapy and HIV infection itself on the development of metabolic abnormalities in patients with lipodystrophy, including insulin resistance and dyslipidaemia, which are associated with an increased risk of diabetes and cardiovascular disease. In addition, an emerging role of HIV and antiretroviral therapy in bone, liver and kidney disease were highlighted. A major focus of the data presented in these areas concerned the identification and evaluation of risk factors and appropriate surrogate markers for defining cardiovascular disease risk as well as other outcomes of long-term treatment. The complexity of defining such risk factors was underscored by data describing the impact of race, age and gender in the progression of metabolic disease and related complications among different HIV-infected populations. Finally, advances in the development of pharmacovigilance reporting systems in resource-limited settings and their impact upon healthcare policies and the provision of patient care were also described.