Aldosterone decreases glucose-stimulated insulin secretion in vivo in mice and in murine islets

The effect of different treatment strategies on glycolipid metabolism disorders and cardiovascular events in primary aldosteronism

Recent studies have explored the association between primary aldosteronism and cardiovascular disease incidence. The association between specific primary aldosteronism treatments and differential improvement in cardiovascular event rates is yet to be established. This study was designed to compare the relative effects of spironolactone therapy and surgical intervention on cardiovascular outcomes among primary aldosteronism patients. This retrospective observational study included 853 primary aldosteronism patients from the First Affiliated Hospital of China Medical University between 2014 and 2022. Patients who had completed abdominal computed tomography (CT) examinations with similar metabolic characteristics and 6-month follow-up analyses were included in this study. These patients were separated into a surgical treatment group (n = 33) and a spironolactone treatment group (n = 51). Demographic data, biochemical analysis results, liver/spleen (L/S) X-ray attenuation ratio, hospitalization frequency, and cardiovascular events were compared between the two groups. The spironolactone group demonstrated significantly improved metabolic characteristics compared to the surgical group, shown by lower BMI, blood pressure, total cholesterol (TC), insulin resistance index (IRI), and reduced non-alcoholic fatty liver disease prevalence. Metabolic parameters did not differ significantly within the surgical treatment group when comparing pre- and postoperative values. The incidence of cardiovascular events was lower in the spironolactone group compared to the surgery group (23/33 vs. 20/51, P < 0.001) despite higher hospitalization rates(37/31 vs. 61/53, P < 0.001). In patients with primary aldosteronism, spironolactone treatment is more effective than surgical intervention in remediating abnormal lipid and glucose metabolism while improving cardiovascular outcomes. Chinese clinical trial registry registration number: ChiCTR2300074574.

Mineralocorticoid receptor overactivation: targeting systemic impact with non-steroidal mineralocorticoid receptor antagonists

The overactivation of the mineralocorticoid receptor (MR) promotes pathophysiological processes related to multiple physiological systems, including the heart, vasculature, adipose tissue and kidneys. The inhibition of the MR with classical MR antagonists (MRA) has successfully improved outcomes most evidently in heart failure. However, real and perceived risk of side effects and limited tolerability associated with classical MRA have represented barriers to implementing MRA in settings where they have been already proven efficacious (heart failure with reduced ejection fraction) and studying their potential role in settings where they might be beneficial but where risk of safety events is perceived to be higher (renal disease). Novel non-steroidal MRA have distinct properties that might translate into favourable clinical effects and better safety profiles as compared with MRA currently used in clinical practice. Randomised trials have shown benefits of non-steroidal MRA in a range of clinical contexts, including diabetic kidney disease, hypertension and heart failure. This review provides an overview of the literature on the systemic impact of MR overactivation across organ systems. Moreover, we summarise the evidence from preclinical studies and clinical trials that have set the stage for a potential new paradigm of MR antagonism.

NR3C1/Glucocorticoid receptor activation promotes pancreatic β-cell autophagy overload in response to glucolipotoxicity

Diabetes is a complex and heterogeneous disorder characterized by chronic hyperglycemia. Its core cause is progressively impaired insulin secretion by pancreatic β-cell failures, usually upon a background of preexisting insulin resistance. Recent studies demonstrate that macroautophagy/autophagy is essential to maintain architecture and function of β-cells, whereas excessive autophagy is also involved in β-cell dysfunction and death. It has been poorly understood whether autophagy plays a protective or harmful role in β-cells, while we report here that it is dependent on NR3C1/glucocorticoid receptor activation. We proved that deleterious hyperactive autophagy happened only upon NR3C1 activation in β-cells under glucolipotoxic conditions, which eventually promoted diabetes. The transcriptome and the N6-methyladenosine (m6A) methylome revealed that NR3C1-enhancement upregulated the RNA demethylase FTO (fat mass and obesity associated) protein in β-cells, which caused diminished m6A modifications on mRNAs of four core Atg (autophagy related) genes (Atg12, Atg5, Atg16l2, Atg9a) and, hence, hyperactive autophagy and defective insulin output; by contrast, FTO inhibition, achieved by the specific FTO inhibitor Dac51, prevented NR3C1-instigated excessive autophagy activation. Importantly, Dac51 effectively alleviated impaired insulin secretion and glucose intolerance in hyperglycemic β-cell specific NR3C1 overexpression mice. Our results determine that the NR3C1-FTO-m6A modifications-Atg genes axis acts as a key mediator of balanced autophagic flux in pancreatic β-cells, which offers a novel therapeutic target for the treatment of diabetes.Abbreviations: 3-MA: 3-methyladenine; AAV: adeno-associated virus; Ac: acetylation; Ad: adenovirus; AL: autolysosome; ATG: autophagy related; AUC: area under curve; Baf A1: bafilomycin A1; βNR3C1 mice: pancreatic β-cell-specific NR3C1 overexpression mice; cFBS: charcoal-stripped FBS; Ctrl: control; ER: endoplasmic reticulum; FTO: fat mass and obesity associated; GC: glucocorticoid; GRE: glucocorticoid response element; GSIS: glucose-stimulated insulin secretion assay; HFD: high-fat diet; HG: high glucose; HsND: non-diabetic human; HsT2D: type 2 diabetic human; i.p.: intraperitoneal injected; KSIS: potassium-stimulated insulin secretion assay; m6A: N6-methyladenosine; MeRIP-seq: methylated RNA immunoprecipitation sequencing; NR3C1/GR: nuclear receptor subfamily 3, group C, member 1; NR3C1-Enhc.: NR3C1-enhancement; NC: negative control; Palm.: palmitate; RNA-seq: RNA sequencing; T2D: type 2 diabetes; TEM: transmission electron microscopy; UTR: untranslated region; WT: wild-type.

Primary hyperaldosteronism is associated with increased mortality and morbidity in patients with hypertension and diabetes

Aims

Primary hyperaldosteronism (PA) is a common cause of hypertension. It is more prevalent in patients with diabetes. We assessed the cardiovascular impact of PA in patients with established hypertension and diabetes.

Methods

Data from the National Inpatient Sample (2008-2016) was used to identify adults with PA with hypertension and diabetes comorbidities and then compared to non-PA patients. The primary outcome was in-hospital death. Secondary outcomes included ischemic stroke, hemorrhagic stroke, acute renal failure, atrial fibrillation, and acute heart failure.

Results

A total of 48,434,503 patients with hypertension and diabetes were included in the analysis, of whom 12,850 (0.03%) were diagnosed with primary hyperaldosteronism (PA). Compared to patients with hypertension and diabetes but no PA, those with PA were more likely to be younger [63(13) vs. 67 (14), male (57.1% vs. 48.3%), and African-Americans (32% vs. 18.5%) (p<0.001 for all). PA was associated with a higher risk of mortality (adjusted OR 1.076 [1.076-1.077]), ischemic stroke [adjusted OR 1.049 (1.049-1.05)], hemorrhagic stroke [adjusted OR 1.05 (1.05-1.051)], acute renal failure [adjusted OR 1.058 (1.058-1.058)], acute heart failure [OR 1.104 (1.104-1.104)], and atrial fibrillation [adjusted OR 1.034 (1.033-1.034)]. As expected, older age and underlying cardiovascular disease were the strongest predictors of mortality. However, the female gender conferred protection [OR 0.889 (0.886-0.892].

Conclusion

Primary hyperaldosteronism in patients with hypertension and diabetes is associated with increased mortality and morbidity.

The role of dietary salt in metabolism and energy balance: Insights beyond cardiovascular disease

Dietary salt (NaCl) is essential to an organism's survival. However, today's diets are dominated by excessive salt intake, which significantly impacts individual and population health. High salt intake is closely linked to cardiovascular disease (CVD), especially hypertension, through a number of well-studied mechanisms. Emerging evidence indicates that salt overconsumption may also be associated with metabolic disorders. In this review, we first summarize recent updates on the mechanisms of salt-induced CVD, the effects of salt reduction and the use of salt substitution as a therapy. Next, we focus on how high salt intake can impact metabolism and energy balance, describing the mechanisms through which this occurs, including leptin resistance, the overproduction of fructose and ghrelin, insulin resistance and altered hormonal factors. A further influence on metabolism worth noting is the reported role of salt in inducing thermogenesis and increasing body temperature, leading to an increase in energy expenditure. While this result could be viewed as a positive metabolic effect because it promotes a negative energy balance to combat obesity, caution must be taken with this frame of thinking given the deleterious consequences of chronic high salt intake on cardiovascular health. Nevertheless, this review highlights the importance of salt as a noncaloric nutrient in regulating whole-body energy homeostasis. Through this review, we hope to provide a scientific framework for future studies to systematically address the metabolic impacts of dietary salt and salt replacement treatments. In addition, we hope to form a foundation for future clinical trials to explore how these salt-induced metabolic changes impact obesity development and progression, and to elucidate the regulatory mechanisms that drive these changes, with the aim of developing novel therapeutics for obesity and CVD.

Secondary diabetes mellitus due to primary aldosteronism

Primary aldosteronism (PA) and diabetes mellitus (DM) are clinical conditions that increase cardiovascular risk. Approximately one in five patients with PA have DM. Nevertheless, the pathophysiology linking these two entities is not entirely understood. In addition, the majority of patients with PA have glucocorticoid co-secretion, which is associated with increased risk of impaired glucose homeostasis. In the present review, we aim to comprehensively discuss all the available research data concerning the interplay between mineralocorticoid excess and glucose metabolism, with separate analysis of the sequalae in muscle, adipose tissue, liver and pancreas. Aldosterone binds both mineralocorticoid and glucocorticoid receptors and amplifies tissue glucocorticoid activity, via 11-β-hydroxysteroid dehydrogenase type 1 stimulation. A clear classification of the molecular events as per specific receptor in insulin-sensitive tissues is impossible, while their synergistic interaction is plausible. Furthermore, aldosterone induces oxidative stress and inflammation, perturbs adipokine expression, thermogenesis and lipogenesis in adipose tissue, and increases hepatic steatosis. In pancreas, enhanced oxidative stress and inflammation of beta cells, predominantly upon glucocorticoid receptor activation, impair insulin secretion. No causality between hypokalemia and impaired insulin response is yet proven; in contrast, hypokalemia appears to be implicated with insulin resistance and hepatic steatosis. The superior efficacy of adrenalectomy in ameliorating glucose metabolism vs. mineralocorticoid receptor antagonists in clinical studies highlights the contribution of non-mineralocorticoid receptor-mediated mechanisms in the pathophysiologic process. The exact role of hypokalemia, the mechanisms linking mineralocorticoid excess with hepatic steatosis, and possible disease-modifying role of pioglitazone warrant further studies.

Leukocyte metabolism in obese type 2 diabetic individuals associated with COVID-19 severity

Recent studies show that the metabolic characteristics of different leukocytes, such as, lymphocytes, neutrophils, and macrophages, undergo changes both in the face of infection with SARS-CoV-2 and in obesity and type 2 diabetes mellitus (DM2) condition. Thus, the objective of this review is to establish a correlation between the metabolic changes caused in leukocytes in DM2 and obesity that may favor a worse prognosis during SARS-Cov-2 infection. Chronic inflammation and hyperglycemia, specific and usual characteristics of obesity and DM2, contributes for the SARS-CoV-2 replication and metabolic disturbances in different leukocytes, favoring the proinflammatory response of these cells. Thus, obesity and DM2 are important risk factors for pro-inflammatory response and metabolic dysregulation that can favor the occurrence of the cytokine storm, implicated in the severity and high mortality risk of the COVID-19 in these patients.

The metabolic phenotype of patients with primary aldosteronism: impact of subtype and sex - a multicenter-study of 3566 Caucasian and Asian subjects

BACKGROUND

Accumulating evidence suggests that primary aldosteronism (PA) is associated with several features of the metabolic syndrome, in particular with obesity, type 2 diabetes mellitus, and dyslipidemia. Whether these manifestations are primarily linked to aldosterone-producing adenoma (APA) or bilateral idiopathic hyperaldosteronism (IHA) remains unclear. The aim of the present study was to investigate differences in metabolic parameters between APA and IHA patients and to assess the impact of treatment on these clinical characteristics.

METHODS

We conducted a retrospective multicenter study including 3566 patients with APA or IHA of Caucasian and Asian origin. We compared the prevalence of metabolic disorders between APA and IHA patients at the time of diagnosis and 1-year post-intervention, with special references to sex differences. Furthermore, correlations between metabolic parameters and plasma aldosterone, renin, or plasma cortisol levels after 1 mg dexamethasone (DST) were performed.

RESULTS

As expected, APA patients were characterized by higher plasma aldosterone and lower serum potassium levels. Only female IHA patients demonstrated significantly worse metabolic parameters than age-matched female APA patients, which were associated with lower cortisol levels upon DST. One-year post-intervention, female adrenalectomized patients showed deterioration of their lipid profile, when compared to patients treated with mineralocorticoid receptor antagonists. Plasma aldosterone levels negatively correlated with the BMI only in APA patients.

CONCLUSIONS

Metabolic alterations appear more prominent in women with IHA. Although IHA patients have worse metabolic profiles, a correlation with cortisol autonomy is documented only in APAs, suggesting an uncoupling of cortisol action from metabolic traits in IHA patients.

Mineralocorticoid Receptor Activation in Vascular Insulin Resistance and Dysfunction

Systemic insulin resistance is characterized by reduced insulin metabolic signaling and glucose intolerance. Mineralocorticoid receptors (MRs), the principal receptors for the hormone aldosterone, play an important role in regulating renal sodium handling and blood pressure. Recent studies suggest that MRs also exist in tissues outside the kidney, including vascular endothelial cells, smooth muscle cells, fibroblasts, perivascular adipose tissue, and immune cells. Risk factors, including excessive salt intake/salt sensitivity, hypertension, and obesity, can lead to the activation of vascular MRs to promote inflammation, oxidative stress, remodeling, and fibrosis, as well as cardiovascular stiffening and microcirculatory impairment. These pathophysiological changes are associated with a diminished ability of insulin to initiate appropriate intracellular signaling events, resulting in a reduced glucose uptake within the microcirculation and related vascular insulin resistance. Therefore, the pharmacological inhibition of MR activation provides a potential therapeutic option for improving vascular function, glucose uptake, and vascular insulin sensitivity. This review highlights recent experimental and clinical data that support the contribution of abnormal MR activation to the development of vascular insulin resistance and dysfunction.

Assessment and Management of Primary Aldosteronism in Pregnancy: A Case-Control Study

CONTEXT

Primary aldosteronism (PA) is a common secondary cause of hypertension. Literature regarding PA in pregnancy has demonstrated poor outcomes.

OBJECTIVE

Compare the management and outcomes of PA in pregnancy to both high and low-risk matched controls.

METHODS

This was a case-control trial conducted in a network of metropolitan hospitals in Sydney, Australia. PA women (positive salt suppression test) with singleton pregnancies delivered after 20 weeks' gestation were matched to women with high- and low-risk pregnancies. Management outcomes included pre-eclampsia prophylaxis and antihypertensive medications required prenatally, antenatally, and postnatally. Maternal outcomes included incidence of pre-eclampsia, gestational diabetes, hypokalemia, mode of delivery, and length of stay postpartum. Neonatal outcomes included gestation, birthweight, intensive care unit admission, and length of stay.

RESULTS

Fifty-nine women with 60 pregnancies were included (20 PA, 20 high risk, and 20 low risk). The number of antihypertensive medications women with PA took prepregnancy was similar to the high-risk group. A similar proportion of women in the PA and high-risk groups were prescribed pre-eclampsia prophylaxis and developed pre-eclampsia. Even after adjustment for several factors, PA was not independently associated with pre-eclampsia development. Women with PA had higher antihypertensive requirements and a longer stay in hospital postpartum than the high-risk group (both P = .02). There was no difference in neonatal adverse outcomes. Four women took epleronone during pregnancy without any adverse effects noted.

CONCLUSION

Women with PA required more antihypertensives and had a longer postpartum length of stay than matched high-risk women, but similar rates of pre-eclampsia. There was no difference in the rate of neonatal intensive care admissions or adverse outcomes for neonates.

Differences in Glycemic Abnormalities Between Primary Aldosteronism and Essential Hypertension: A Systematic Review and Meta-Analysis

Background

The relationship of glycemic abnormalities between primary aldosteronism (PA) patients and essential hypertension (EH) patients is still debatable. This meta-analysis aimed to explore differences in the prevalence of glycemic abnormalities and levels of abnormal glucose metabolism in PA and EH patients.

Methods

A search was performed using PubMed, Scopus, Cochrane and Web of Science databases from their inception through January 2022. Inclusion criteria for this study were 1) observational studies which contained specific data of interest, 2) studies including data which compared adult PA and EH patients and 3) studies which used appropriate methods to diagnose PA. Risk ratio (RR) or standardized mean difference (SMD) with a 95% confidence interval (95% CI) was calculated.

Results

Twenty-six studies involving 53,186 patients were included in the meta-analysis. Patients with PA demonstrated significantly higher overall incidence of glycemic abnormalities than patients with EH [RR 1.54; 95% CI (1.20,1.98)]. Risk of diabetes mellitus (DM) and impaired glucose tolerance (IGT) in PA patients were higher than in EH patients [RR 1.27; 95%CI (1.08, 1.49) and RR 2.99; 95%CI (1.74, 5.16), respectively]. There was no statistically significant difference of risk between these groups for impaired fasting glucose (IFG) [RR 1.70; 95%CI (0.55, 5.26)]. Moderate heterogeneity was observed in overall glycemic abnormalities outcomes. A high level of heterogeneity was observed for IFG, while the level was low for DM and IGT.

Conclusions

PA patients have a higher risk of glycemic abnormalities than in EH patients. Further study should be conducted to investigate underlying mechanisms of glycemic abnormalities in PA.

Systematic Review Registration

www.inplasy.com, INPLASY, identifier 202220004.

Association of renin and aldosterone with glucose metabolism in a Western European population: the KORA F4/FF4 study

INTRODUCTION

Primary aldosteronism is associated with impaired glucose tolerance. Whether plasma aldosterone and/or renin concentrations are associated with type 2 diabetes and continuous measures of glucose metabolism in the general population is still under debate.

RESEARCH DESIGN AND METHODS

The analyses included 2931 participants of the KORA F4 study at baseline and 2010 participants of the KORA FF4 study after a median follow-up of 6.5 years. The associations of active plasma renin and aldosterone concentrations with type 2 diabetes and continuous measures of glucose metabolism were assessed using logistic and linear regression models. Results were adjusted for sex, age, body mass index (BMI), estimated glomerular filtration rate, potassium, use of ACE inhibitors, angiotensin receptor blockers, beta blockers, diuretics and calcium channel blockers.

RESULTS

Cross-sectionally, renin was associated with type 2 diabetes (OR per SD: 1.25, 95% CI 1.10 to 1.43, p<0.001), fasting glucose, 2-hour glucose, insulin, proinsulin, HOMA-B (homeostasis model assessment of beta cell function) and HOMA-IR (homeostasis model assessment of insulin resistance) (all p values <0.001). Aldosterone was not associated with type 2 diabetes (OR: 1.04, 95% CI 0.91 to 1.19; p=0.547) but with insulin, proinsulin and HOMA-IR (all p values <0.001). The aldosterone-renin ratio was inversely associated with type 2 diabetes and several measures of glucose metabolism. Longitudinally, neither renin (OR: 1.12, 95% CI 0.92 to 1.36) nor aldosterone (OR: 0.91, 95% CI 0.74 to 1.11) were associated with incident type 2 diabetes. Renin was inversely associated with changes of insulin concentrations.

CONCLUSIONS

In the KORA F4/FF4 study, renin and aldosterone were not associated with incident type 2 diabetes and largely unrelated to changes of measures of glucose metabolism. Cross-sectionally, aldosterone was associated with surrogate parameters of insulin resistance. However, these associations were not independent of renin.

Effects of sacubitril/valsartan on both metabolic parameters and insulin resistance in prediabetic non-obese patients with heart failure and reduced ejection fraction

BACKGROUND

The effects of sacubitril/valsartan (sac/val) on metabolic parameters and insulin resistance (IR) in non-obese/prediabetic patients have not been previously described.

AIM

To evaluate the effects of sac/val on glycemic and metabolic parameters, Homeostatic Model Assessment of IR (HOMA-IR), and echocardiographic parameters in prediabetic patients with heart failure with reduced ejection fraction (HFrEF).

METHODS

Fifty-nine patients with HFrEF (EF < 35%) but without obesity and/or type 2 diabetes mellitus have been enrolled. All the patients at baseline and week 24 underwent complete anthropometrical evaluation and were subjected to an echocardiogram test. IR has been assessed by HOMA-IR.

RESULTS

After 24-week of treatment with sac/val, a significant reduction in fasting plasma glucose (109 ± 9 vs 103 ± 8 mg/dl, p < 0.0001), fasting plasma insulin (16 ± 4 vs 10 ± 4 UI/L), and hemoglobin A1c (HbA1c) value (6% ± 0.5% vs 5.3% ± 0.3%, p < 0.0001) was observed. Similarly, we observed a significant improvement in IR (HOMA-IR, 4.4 ± 0.9 vs 2.5 ± 0.6, p < 0.0001). The echocardiogram evaluation showed a significant reduction of the left ventricular end-diastolic volume (168 ± 24 vs 158 ± 22 ml, p < 0.05), a significant reduction of the left ventricular end-systolic volume (111 ± 26 vs 98 ± 22 ml, p < 0.005), and a significant reduction of E/e' ratio. Sac/val use was also associated with an average 5.1% increase in ejection fraction.

CONCLUSIONS

Our data seem to indicate that sal/val enhances metabolic control and improves insulin resistance also in prediabetic non-obese patients with HFrEF.

Mineralocorticoid receptor in non-alcoholic fatty liver disease

Liver diseases are the fourth common death in Europe responsible for about 2 million death per year worldwide. Among the known detrimental causes for liver dysfunction are virus infections, intoxications and obesity. The mineralocorticoid receptor (MR) is a ligand-dependent transcription factor activated by aldosterone or glucocorticoids but also by pathological milieu factors. Canonical actions of the MR take place in epithelial cells of kidney, colon and sweat glands and contribute to sodium reabsorption, potassium secretion and extracellular volume homeostasis. The non-canonical functions can be initiated by inflammation or an altered micro milieu leading to fibrosis, hypertrophy and remodeling in various tissues. This narrative review summarizes the evidence regarding the role of MR in portal hypertension, non-alcoholic fatty liver disease, liver fibrosis and cirrhosis, demonstrating that inhibition of the MR in vivo seems to be beneficial for liver function and not just for volume regulation. Unfortunately, the underlying molecular mechanisms are still not completely understood.

Nonsteroidal mineralcorticoid receptor antagonists: Novel therapeutic implication in the management of patients with type 2 diabetes

Growing evidencehas described a correlation between aldosterone, obesity, and insulin resistance, suggesting that adipocyte-related factors and mineralocorticoid receptor (MR) overactivation may alter aldosterone secretion, potentially leading to obesity and glucose intolerance. Preclinical studies showed that pharmacological antagonism of MR prevents white adipose tissue dysfunction(s) and expansion, activates brown adipose tissue, and improves glucose tolerance. The clinical use of nonsteroidal MR antagonists has been shown to reduce the risk of diabetic kidney disease progression and cardiovascular events in patients with diabetes. This review aims to summarize the effects of pharmacological MR blockade on obesity and its associated metabolic comorbidities, with a particular focus on the therapeutic implications of nonsteroidal MR antagonists in the management of patients with diabetes.

Eight weeks of mineralocorticoid blockade does not improve insulin sensitivity in type 2 diabetes

Individuals with type 2 diabetes have an increased risk of cardiovascular disease. A correlation between plasma aldosterone and hyperinsulinemia has been demonstrated in vivo, and hyperinsulinemia and insulin resistance are independently associated with the development of cardiovascular complications. We investigated if mineralocorticoid blockade (Eplerenone) improves insulin sensitivity in individuals with type 2 diabetes compared to healthy controls. We included 13 participants with type 2 diabetes (<5 years; male/female, Caucasians) and 10 healthy control participants (male/female, Caucasians). On 2 experimental days, before and at the end of the 8 weeks of treatment with mineralocorticoid blockade, a two-stage hyperinsulinemic-isoglycemic clamp (20 and 50 mU∙m-2 min-1 ) was performed for the determination of insulin sensitivity. No change in insulin sensitivity was detected at the end of the mineralocorticoid blockade in the individuals with type 2 diabetes or the healthy controls. Both before and at the end of the treatment with mineralocorticoid blockade, the individuals with type 2 diabetes had a lower insulin sensitivity compared to healthy controls. In conclusion, mineralocorticoid receptor blockade does not appear to improve insulin sensitivity in individuals with type 2 diabetes. CLINICAL TRIAL REGISTRATION: NCT03017703. https://clinicaltrials.gov/ct2/show/NCT03017703.

Carbonyl reductase 1 amplifies glucocorticoid action in adipose tissue and impairs glucose tolerance in lean mice

OBJECTIVE

Carbonyl reductase 1 (Cbr1), a recently discovered contributor to tissue glucocorticoid metabolism converting corticosterone to 20β-dihydrocorticosterone (20β-DHB), is upregulated in adipose tissue of obese humans and mice and may contribute to cardiometabolic complications of obesity. This study tested the hypothesis that Cbr1-mediated glucocorticoid metabolism influences glucocorticoid and mineralocorticoid receptor activation in adipose tissue and impacts glucose homeostasis in lean and obese states.

METHODS

The actions of 20β-DHB on corticosteroid receptors in adipose tissue were investigated first using a combination of in silico, in vitro, and transcriptomic techniques and then in vivo administration in combination with receptor antagonists. Mice lacking one Cbr1 allele and mice overexpressing Cbr1 in their adipose tissue underwent metabolic phenotyping before and after induction of obesity with high-fat feeding.

RESULTS

20β-DHB activated both the glucocorticoid and mineralocorticoid receptor in adipose tissue and systemic administration to wild-type mice induced glucose intolerance, an effect that was ameliorated by both glucocorticoid and mineralocorticoid receptor antagonism. Cbr1 haploinsufficient lean male mice had lower fasting glucose and improved glucose tolerance compared with littermate controls, a difference that was abolished by administration of 20β-DHB and absent in female mice with higher baseline adipose 20β-DHB concentrations than male mice. Conversely, overexpression of Cbr1 in adipose tissue resulted in worsened glucose tolerance and higher fasting glucose in lean male and female mice. However, neither Cbr1 haploinsfficiency nor adipose overexpression affected glucose dyshomeostasis induced by high-fat feeding.

CONCLUSIONS

Carbonyl reductase 1 is a novel regulator of glucocorticoid and mineralocorticoid receptor activation in adipose tissue that influences glucose homeostasis in lean mice.

Insulin sensitivity and pancreatic β-cell function in patients with primary aldosteronism

BACKGROUND

Primary aldosteronism (PA) is associated with an increased risk for dysglycemia. However, the effects of hyperaldosteronism on insulin sensitivity and β-cell function are unclear.

METHODS

Using a cross-sectional study design, we assessed insulin sensitivity and pancreatic β-cell function from an oral glucose tolerance test (OGTT) in patients from two cohorts: subjects with PA (n = 21) and essential hypertension control (EHC) subjects (n = 22). Age, sex, BMI, and mean arterial pressure adjusted measures of insulin sensitivity and β-cell function were compared between the groups.

RESULTS

PA individuals were less insulin sensitive compared to EHC subjects (Quantitative insulin sensitivity check index [QUICKI]: 0.340 ± 0.006 vs. 0.374 ± 0.013, p < 0.001; Matsuda index: 4.14 ± 0.49 vs. 7.87 ± 1.42, p < 0.001; S_I: 11.45 ± 4.85 vs. 21.23 ± 6.11 dL/kg/min per μU/mL, p = 0.02). The hepatic insulin resistance index (HIRI) was higher in PA subjects (PA: 5.61 ± 1.01 vs. EHC: 4.13 ± 0.61, p = 0.002). The insulinogenic index (IGI), an index of β-cell function was higher in the PA cohort (PA: 1.49 ± 0.27 vs. 1.11 ± 0.21 μU/mL/mg/dL, p = 0.03). However, the oral disposition index (DI) was similar between the groups (PA: 4.77 ± 0.73 vs. EHC: 5.46 ± 0.85, p = 0.42), which likely accounts for the similar glucose tolerance between the two cohorts, despite lower sensitivity.

CONCLUSIONS

In summary, insulin sensitivity is significantly lower in PA with an appropriately compensated β-cell function. These results suggest that excess aldosterone and/or other steroids in the context of PA may negatively affect insulin action without adversely impacting β-cell function.

Mineralocorticoid receptors in the pathogenesis of insulin resistance and related disorders: from basic studies to clinical disease

Aldosterone is a steroid hormone that regulates blood pressure and cardiovascular function by acting on renal and vascular mineralocorticoid receptors (MRs) to promote sodium retention and modulate endothelial function. Indeed, MRs are expressed in endothelial cells, vascular smooth muscle cells, adipocytes, immune cells, skeletal muscle cells, and cardiomyocytes. Excessive aldosterone and associated MR activation impair insulin secretion, insulin metabolic signaling to promote development of diabetes, and the related cardiometabolic syndrome. These adverse effects of aldosterone are mediated, in part, via increased inflammation, oxidative stress, dyslipidemia, and ectopic fat deposition. Therefore, inhibition of MR activation may have a beneficial effect in prevention of impaired insulin metabolic signaling, type 2 diabetes, and cardiometabolic disorders. This review highlights findings from the recent surge in research regarding MR-related cardiometabolic disorders as well as our contemporary understanding of the detrimental effects of excess MR activation on insulin metabolic signaling.

The mineralocorticoid receptor-an emerging player in metabolic syndrome?

Metabolic syndrome is a cluster of conditions that increase the risk of cardiovascular diseases, and comprises obesity, hypertension, impaired glucose metabolism and dyslipidaemia. It is well recognised that the mineralocorticoid receptor (MR) plays an important role in blood pressure regulation via its effect on salt and water retention in renal tubules, with hypertension being a key feature in primary aldosteronism patients with excess adrenal production of aldosterone, the primary ligand for MRs in the epithelial tissues. MRs are also expressed in a number of non-epithelial tissues including adipose tissue; in these tissues, glucocorticoids or cortisol can also activate MRs due to low levels of 11-beta-hydroxysteroid-dehydrogenase type 2 (11-βHSD2), the enzyme which inactivates cortisol. There is increasing evidence suggesting that over-activation of MRs plays a role in the pathophysiology of the other components of metabolic syndrome, promoting adiposity, inflammation and glucose intolerance, and that MR antagonists may confer beneficial effects on energy and substrate homeostasis and cardiometabolic diseases. This review discusses the advances in the literature shedding light on the MR as an emerging player in metabolic syndrome.

Metabolic and Energy Imbalance in Dysglycemia-Based Chronic Disease

Metabolic flexibility is the ability to efficiently adapt metabolism based on nutrient availability and requirement that is essential to maintain homeostasis in times of either caloric excess or restriction and during the energy-demanding state. This regulation is orchestrated in multiple organ systems by the alliance of numerous metabolic pathways under the master control of the insulin-glucagon-sympathetic neuro-endocrine axis. This, in turn, regulates key metabolic enzymes and transcription factors, many of which interact closely with and culminate in the mitochondrial energy generation machinery. Metabolic flexibility is compromised due to the continuous mismatch between availability and intake of calorie-dense foods and reduced metabolic demand due to sedentary lifestyle and age-related metabolic slowdown. The resultant nutrient overload leads to mitochondrial trafficking of substrates manifesting as mitochondrial dysfunction characterized by ineffective substrate switching and incomplete substrate utilization. At the systemic level, the manifestation of metabolic inflexibility comprises reduced skeletal muscle glucose disposal rate, impaired suppression of hepatic gluconeogenesis and adipose tissue lipolysis manifesting as insulin resistance. This is compounded by impaired β-cell function and progressively reduced β-cell mass. A consequence of insulin resistance is the upregulation of the mitogen-activated protein kinase pathway leading to a pro-hypertensive, atherogenic, and thrombogenic environment. This is further aggravated by oxidative stress, advanced glycation end products, and inflammation, which potentiates the risk of micro- and macro-vascular complications. This review aims to elucidate underlying mechanisms mediating the onset of metabolic inflexibility operating at the main target organs and to understand the progression of metabolic diseases. This could potentially translate into a pharmacological tool that can manage multiple interlinked conditions of dysglycemia, hypertension, and dyslipidemia by restoring metabolic flexibility. We discuss the breadth and depth of metabolic flexibility and its impact on health and disease.

Non-Alcoholic Fatty Liver Disease and Hypokalemia in Primary Aldosteronism Among Chinese Population

BACKGROUND

In recent years, evidence that aldosteronism is a risk factor for metabolic disorders has increased. This study was designed to investigate the role of nonalcoholic fatty liver disease (NAFLD) and hypokalemia in primary aldosteronism (PA).

METHODS

A total of 222 patients diagnosed with PA and 222 non-PA patients were included in our study. Demographic data, medical histories, clinical evaluations, complete blood counts, serum biochemical analyses, aldosterone and potassium levels were obtained. Data are presented as the means ± standard deviation (SD). To compare the parameters between cases and controls, Student's t-tests or Mann-Whitney U tests were used for continuous variables, and χ2 tests were used for categorical variables. Pearson correlation analysis was used to define relationships between pairs of parameters. A two-sided P < 0.05 was considered statistically significant. Multivariate logistic regression was performed to assess the independent effects of potassium and other metabolic variables on NAFLD in PA patients.

RESULTS

The diagnosis of NAFLD was more common in PA patients (n=222, 35.1%) than in non-PA subjects (29.7%). PA patients with and without NAFLD had similar metabolic imbalance characteristics. In PA patients with hypokalemia, relatively higher prevalences of NAFLD (44% vs. 27%, P < 0.05) and diabetes mellitus (19.8% vs. 9.9%, P < 0.05) were observed. Hypokalemic PA patients had a worse metabolic status than PA patients without hypokalemia, including higher body mass index (BMI) (25.4 ± 3.4 vs. 24.1 ± 3.9 kg/m², P < 0.05), more severe dyslipidemia as well as insulin resistance, higher serum uric acid levels (354 ± 95 vs. 319 ± 87 μmol/L, P < 0.01) and aggravated inflammation.

CONCLUSION

The prevalence of NAFLD was higher in PA patients than in non-PA patients, although the patterns of obesity, dyslipidemia and insulin resistance were similar. Hypokalemic PA patients had a worse metabolic status than normokalemic PA patients. This study provides new insights that can inform further mechanistic studies about metabolic imbalance in patients with aldosteronism.

Targeting the renin angiotensin system for the treatment of anxiety and depression

Emotional disorders like anxiety and depression are responsible for considerable morbidity and mortality all over the world. Several antidepressant and anxiolytic medications are available for the treatment of anxiety and depression. However, a significant number of patients either do not respond to these medications or respond inadequately. Hence, there is a need to identify novel targets for the treatment of anxiety and depression. In this review we focus on the renin angiotensin system (RAS) as a potential target for the treatment of these disorders. We review work that has evaluated the effects of various compounds targeting the RAS on anxiety- and depression-like behaviors. Further, we suggest future work that must be carried out to fully exploit the RAS for the treatment of anxiety and depression. The RAS provides an attractive target for both the identification of novel anxiolytic and antidepressant medications and/or for enhancing the efficacy of currently available medications used for the treatment of anxiety and depression.

Hypercoagulopathy and Adipose Tissue Exacerbated Inflammation May Explain Higher Mortality in COVID-19 Patients With Obesity

COVID-19, caused by SARS-CoV-2, is characterized by pneumonia, lymphopenia, exhausted lymphocytes and a cytokine storm. Several reports from around the world have identified obesity and severe obesity as one of the strongest risk factors for COVID-19 hospitalization and mechanical ventilation. Moreover, countries with greater obesity prevalence have a higher morbidity and mortality risk of developing serious outcomes from COVID-19. The understanding of how this increased susceptibility of the people with obesity to develop severe forms of the SARS-CoV-2 infection occurs is crucial for implementing appropriate public health and therapeutic strategies to avoid COVID-19 severe symptoms and complications in people living with obesity. We hypothesize here that increased ACE2 expression in adipose tissue displayed by people with obesity may increase SARS-CoV-2 infection and accessibility to this tissue. Individuals with obesity have increased white adipose tissue, which may act as a reservoir for a more extensive viral spread with increased shedding, immune activation and pro-inflammatory cytokine amplification. Here we discuss how obesity is related to a pro-inflammatory and metabolic dysregulation, increased SARS-CoV-2 host cell entry in adipose tissue and induction of hypercoagulopathy, leading people with obesity to develop severe forms of COVID-19 and also death. Taken together, it may be crucial to better explore the role of visceral adipose tissue in the inflammatory response to SARS-CoV-2 infection and investigate the potential therapeutic effect of using specific target anti-inflammatories (canakinumab or anakinra for IL-1β inhibition; anti-IL-6 antibodies for IL-6 inhibition), anticoagulant or anti-diabetic drugs in COVID-19 treatment of people with obesity. Defining the immunopathological changes in COVID-19 patients with obesity can provide prominent targets for drug discovery and clinical management improvement.

Hyperketonemia GWAS and parity-dependent SNP associations in Holstein dairy cows intensively sampled for blood β-hydroxybutyrate concentration

Hyperketonemia (HYK) is a metabolic disorder that affects early postpartum dairy cows; however, there has been limited success in identifying genomic variants contributing to HYK susceptibility. We conducted a genome-wide association study (GWAS) using HYK phenotypes based on an intensive screening protocol, interrogated genotype interactions with parity group (GWIS), and evaluated the enrichment of annotated metabolic pathways. Holstein cows were enrolled into the experiment after parturition, and blood samples were collected at four timepoints between 5 and 18 days postpartum. Concentration of blood β-hydroxybutyrate (BHB) was quantified cow-side via a handheld BHB meter. Cows were labeled as a HYK case when at least one blood sample had BHB ≥ 1.2 mmol/L, and all other cows were considered non-HYK controls. After quality control procedures, 1,710 cows and 58,699 genotypes were available for further analysis. The GWAS and GWIS were performed using the forward feature select linear mixed model method. There was evidence for an association between ARS-BFGL-NGS-91238 and HYK susceptibility, as well as parity-dependent associations to HYK for BovineHD0600024247 and BovineHD1400023753. Candidate genes annotated to these single nuclear polymorphism associations have been previously associated with obesity, diabetes, insulin resistance, and fatty liver in humans and rodent models. Enrichment analysis revealed focal adhesion and axon guidance as metabolic pathways contributing to HYK etiology, while genetic variation in pathways related to insulin secretion and sensitivity may affect HYK susceptibility in a parity-dependent matter. In conclusion, the present work proposes several novel marker associations and metabolic pathways contributing to genetic risk for HYK susceptibility.

Different pathogenesis of glucose intolerance in two subtypes of primary aldosteronism: Aldosterone-producing adenoma and idiopathic hyperaldosteronism

AIMS/INTRODUCTION

An increased risk of diabetes mellitus has been reported in primary aldosteronism, but the pathogenesis of glucose intolerance between the primary aldosteronism subtypes remains unclear. This study aimed to evaluate glucose metabolism in oral glucose tolerance test between aldosterone-producing adenoma and idiopathic hyperaldosteronism, and characterize patients with improved glucose intolerance after primary aldosteronism treatment.

MATERIALS AND METHODS

Oral glucose tolerance test was carried out in 116 patients who were diagnosed with primary aldosteronism and received adrenal venous sampling for subtyping. Oral glucose tolerance test was re-evaluated after starting the treatment of primary aldosteronism for those who had glucose intolerance before the treatment.

RESULTS

A total of 46.4% and 52.3% of patients with aldosterone-producing adenoma and idiopathic hyperaldosteronism, respectively, were diagnosed with impaired glucose tolerance or diabetes. The insulinogenic index was significantly lower in aldosterone-producing adenoma than in idiopathic hyperaldosteronism (P = 0.045), whereas the Matsuda insulin sensitivity index was significantly higher in aldosterone-producing adenoma than in idiopathic hyperaldosteronism (P = 0.022). After the treatment of primary aldosteronism, glucose intolerance was improved in 66.6% and 45.8% of aldosterone-producing adenoma and idiopathic hyperaldosteronism, respectively. The presence of obesity and central obesity were significantly lower in patients who improved glucose intolerance after the treatment of primary aldosteronism as compared with those not improved (P = 0.013 and P = 0.033, respectively).

CONCLUSIONS

Insulin secretion impairment and insulin resistance play pathogenic roles for glucose intolerance in aldosterone-producing adenoma and idiopathic hyperaldosteronism, respectively. In addition, primary aldosteronism treatments can ameliorate glucose intolerance more effectively in patients without obesity and/or central obesity.

Mineralocorticoids, glucose homeostasis and type 2 diabetes mellitus: The Henan Rural Cohort study

AIMS

We aimed to evaluate the associations of mineralocorticoids with type 2 diabetes mellitus (T2DM) and glucose homeostasis among rural Chinese adults.

METHODS

A total of 2713 participants were selected from the Henan Rural Cohort study. Serum mineralocorticoids were measured by liquid chromatography-tandem mass spectrometry. Logistic regression and restricted cubic splines were employed to evaluate the associations of mineralocorticoids with pre-diabetes and T2DM. Linear regression was implemented to assess the associations of aldosterone and 11-deoxycorticosterone with different markers of glucose homeostasis by different diabetes status.

RESULTS

Elevated aldosterone and 11-deoxycorticosterone were associated with an increased prevalence of pre-diabetes and T2DM (P < 0.05), with a nonlinear dose-response trend, but the association between 11-deoxycorticosterone and T2DM was no statistical significance after adjustment. A 100% increase in ln-aldosterone was associated with a 0.029 mg/dl higher fasting plasma glucose (FPG) and a 1.2% higher HOMA2-IR among those with normal glucose tolerance (NGT), and related to a 0.034 mg/dl lower FPG, a 1.1% higher HbA1c and a 1.3% higher HOMA2-β among individuals with pre-diabetes. A 100% increment in ln-11-deoxycorticosterone was associated with a 16% increase in HbA1c and a 5.6% decrease in HOMA2-β in participants with T2DM.

CONCLUSIONS

Higher aldosterone and 11-deoxycorticosterone are associated with T2DM risk and glucose homeostasis disorder among different diabetes status.

Determining the Prevalence of Primary Aldosteronism in Patients With New-Onset Type 2 Diabetes and Hypertension

CONTEXT

Despite a high prevalence of hypertension in diabetes and close relationship between primary aldosteronism (PA) and glucose metabolism, few study concerns the prevalence of PA in diabetes with hypertension.

OBJECTIVE

This study aimed to detect the prevalence of PA in patients with new-onset type 2 diabetes (T2D) and hypertension and to explore the association between PA and diabetes.

METHODS

A total of 256 outpatients with new-onset T2D and hypertension were screened for PA. Plasma aldosterone concentration (PAC), plasma renin activity (PRA) were measured. Patients with an aldosterone renin activity ratio (ARR) ≥ 30 ng/dL/ng/mL/h and PAC ≥ 15 ng/dL underwent confirmatory captopril challenge test (CCT) for PA. The diagnostic criteria for PA were, after CCT, (1) PAC decreased < 30%, (2) ARR maintained ≥ 30 ng/dL/ng/mL/h, and (3) PAC was ≥ 11 ng/dL.

RESULTS

Of 256 consecutive patients, 99 (39%) were positive for the screening test, and 49 (19%) were diagnosed with PA. Compared with those in groups A (screening test -) and B (screening test +, CCT -), patients in group C (diagnosed with PA) had a higher percentage of systolic blood pressure of ≥ 160 mmHg, less family history of hypertension, and lower serum potassium. Patients in group B and C had higher PAC and ARR levels, but lower PRA than those in group A. Homeostatic model assessment for insulin resistance (HOMA-IR) was positively associated with PAC level among the diabetic patients.

CONCLUSION

The prevalence of PA in new-onset T2D patients with hypertension is at least 19%. Higher aldosterone may be related with insulin resistance in patients with diabetes.

Primary Aldosteronism Decreases Insulin Secretion and Increases Insulin Clearance in Humans

Primary aldosteronism is a frequent cause of resistant hypertension and is associated with an increased risk of developing diabetes mellitus. Aldosterone impairs insulin secretion in isolated islets, and insulin secretion is increased in aldosterone synthase-deficient mice. We hypothesized that treatment for primary aldosteronism increases insulin secretion and insulin sensitivity in humans. We conducted a prospective cohort study in patients with primary aldosteronism, with assessment of glucose metabolism before and 3 to 12 months after treatment. Participants underwent treatment for primary aldosteronism with adrenalectomy or a mineralocorticoid receptor antagonist at the discretion of their treating physician. We assessed insulin secretion and insulin sensitivity by hyperglycemic and hyperinsulinemic-euglycemic clamps, respectively, on 2 study days after a 5-day standardized diet. After treatment, the C-peptide and insulin response during the hyperglycemic clamp increased compared with pretreatment (ΔC-peptide at 90-120 minutes +530.5±384.1 pmol/L, P=0.004; Δinsulin 90-120 minutes +183.0±122.6, P=0.004). During hyperinsulinemic-euglycemic clamps, insulin sensitivity decreased after treatment (insulin sensitivity index 30.7±6.2 versus 18.5±4.7 nmol·kg^-1·min^-1·pmol^-1·L; P=0.02). Insulin clearance decreased after treatment (872.8±207.6 versus 632.3±178.6 mL/min; P=0.03), and disposition index was unchanged. We conclude that the insulin response to glucose increases and insulin clearance decreases after treatment for primary aldosteronism, and these effects were not due to alterations in creatinine clearance or plasma cortisol. These studies may provide further insight into the mechanism of increased diabetes mellitus risk in primary aldosteronism.

Effects of Primary Aldosteronism and Different Therapeutic Modalities on Glucose Metabolism

Despite findings that aldosterone impairs glucose metabolism, studies concerning the effect of primary aldosteronism (PA) and its treatment on glucose metabolism are controversial. We aimed to determine glucose metabolism in PA and the effect of the treatment modality. We compared glucose metabolism between PA patients (N = 286) and age-, sex-, and body mass index-matched controls (N = 816), and the changes in glucose metabolism depending on the treatment modality (adrenalectomy vs. spironolactone treatment). Hyperglycemia including diabetes mellitus (DM; 19.6% vs. 13.1%, p = 0.011) was more frequent in PA patients. Hyperglycemia was also more frequent in PA patients without subclinical hypercortisolism (SH: p < 0.001) and in those regardless of hypokalemia (p < 0.001-0.001). PA patients and PA patients without SH had higher DM risk (odds ratio (OR); 95% confidence interval (CI): 1.63; 1.11-2.39 and 1.65; 1.08-2.51, respectively) after adjusting confounders. In PA patients, there was significant decrease in the DM prevalence (21.3% to 16.7%, p = 0.004) and fasting plasma glucose (p = 0.006) after adrenalectomy. However, there was no significant change in them after spironolactone treatment. Adrenalectomy was associated with more improved glucose status than spironolactone treatment (OR; 95% CI: 2.07; 1.10-3.90). Glucose metabolism was impaired in PA, regardless of hypokalemia and SH status, and was improved by adrenalectomy, but not spironolactone treatment.

Insulin secretion and sensitivity before and after surgical treatment for aldosterone-producing adenoma

AIM

Primary aldosteronism, which is usually caused by an aldosterone-producing tumour, affects glucose metabolism. The effects of this condition on insulin secretion and insulin sensitivity have remained unclear, however. To gain insight into the influence of primary aldosteronism on glucose tolerance, various parameters related to insulin secretion or insulin sensitivity in patients with an aldosterone-producing tumour were comprehensively analyzed.

METHODS

To assess 14 patients with an aldosterone-producing tumour, hyperglycaemic and hyperinsulinaemic-euglycaemic clamp tests as well as oral glucose tolerance tests (OGTTs) were performed before and after tumour excision. Time between presurgical analysis and surgery was 27-559 (194±132) days, and 14-142 (51±38) days between surgery and postsurgical analysis. Various parameters related to insulin secretion or sensitivity as determined by OGTT as well as hyperglycaemic and hyperinsulinaemic-euglycaemic clamp analyses were evaluated.

RESULTS

Surgical treatment of tumours ameliorated hypokalaemia and reduced plasma aldosterone levels. First and second phases of insulin secretion during the hyperglycaemic clamp, as well as the insulinogenic index and total insulin secretion measured during OGTT, were also improved after surgery. In addition, the insulin sensitivity index determined during the hyperinsulinaemic-euglycaemic clamp was reduced after surgery.

CONCLUSION

Primary aldosteronism impairs insulin secretion.

Effect of the mineralocorticoid receptor antagonist eplerenone on liver fat and metabolism in patients with type 2 diabetes: A randomized, double-blind, placebo-controlled trial (MIRAD trial)

AIM

To investigate whether the mineralocorticoid receptor antagonist eplerenone has beneficial effects on liver fat and metabolism in patients with type 2 diabetes (T2D), the mineralocorticoid receptor antagonist in type 2 diabetes (MIRAD) trial.

MATERIAL AND METHODS

In this 26-week, double-blind, randomized, placebo-controlled trial, we enrolled 140 patients with T2D and high risk of cardiovascular disease. Patients were randomized 1:1 to either eplerenone with a target dose of 200 mg/day for patients with estimated glomerular filtration rate (eGFR) of 60 mL/min per 1.73 m² or more and 100 mg/day for patients with eGFR between 41 and 59 mL/min per 1.73 m² or placebo. The primary outcome measure was change in liver fat by proton magnetic resonance spectroscopy at week 26 from baseline; secondary outcomes were changes in metabolism, and safety by incident hyperkalaemia.

RESULTS

No changes in liver fat in the eplerenone group 0.91% (95% CI -0.57 to 2.39) or the placebo group -1.01% (-2.23 to 0.21) were found. The estimated absolute treatment difference was 1.92% (-3.81 to 0.01; P = 0.049). There was no beneficial impact on supporting secondary outcome variables of metabolism as fat mass distribution, lipid metabolism or insulin resistance. Despite a high dosage of eplerenone 164 versus 175 mg in patients treated with placebo (P = 0.228), the number of patients with incident hyperkalaemia (≥5.5 mmol/L) was low, with six in the eplerenone versus two in the placebo group (P = 0.276).

CONCLUSION

The addition of high doses of eplerenone to background antidiabetic and antihypertensive therapy does not show beneficial effects on liver fat and metabolism in patients with T2D.

Vascular Dysfunction and Insulin Resistance in Aging

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Insulin was discovered in 1922 by Banting and Best. Since that time, extensive research on the mechanisms of insulin activity and action has continued. Currently, it is known that the role of insulin is much greater than simply regulating carbohydrate metabolism. Insulin in physiological concentration is also necessary to maintain normal vascular function.

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Insulin resistance is defined as a pathological condition characterized by reduced sensitivity of skeletal muscles, liver, and adipose tissue, to insulin and its downstream metabolic effects under normal serum glucose concentrations. There are also selective forms of insulin resistance with unique features, including vascular insulin resistance. Insulin resistance, both classical and vascular, contributes to vascular impairment resulting in increased risk of cardiovascular disease. Furthermore, in the elderly population, additional factors including redistribution of fat concentrations, low-grade inflammation, and decreased self-repair capacity [or cell senescence] amplify the vascular abnormalities related to insulin resistance.

Combined oral contraceptive in female mice causes hyperinsulinemia due to β-cell hypersecretion and reduction in insulin clearance

Oral contraception is the most commonly used interventional method in the world. However, several women employ the continuous use of these hormones to avoid pre- and menstruation discomforts. Some studies indicate that oral contraceptives are associated with disturbances in glycemia and the effects of the use of a continuous regime are poorly elucidated. Herein, we evaluated the effects of the continuous administration of a combined oral contraceptive (COC) composed by ethinyl estradiol (EE) and drospirenone (DRSP) on glucose homeostasis in female mice. Adult Swiss mice received 0.6 μg EE and 60 μg DRSP (COC group) or vehicle [control (CTL)] daily by gavage for 35 days. COC treatment had no effect on body weight or adiposity, but increased uterus weight and induced hepatomegaly. Importantly, COC females displayed normal glycemia and glucose tolerance, but hyperinsulinemia and lower plasma C-peptide/insulin ratio, indicating reduced insulin clearance. Furthermore, COC mice displayed reduced protein content of the β subunit of the insulin receptor (IRβ) in the liver. Additionally, pancreatic islets isolated from COC mice secreted more insulin in response to increasing glucose concentrations. This effect was associated with the activity of steroid hormones, since INS-1E cells incubated with EE plus DRSP also secreted more insulin. Therefore, we provide the first evidence that the continuous administration of EE and DRSP lead to hyperinsulinemia, due to enhancement of insulin secretion and the reduction of insulin degradation, which possibly lead to the down-regulation of hepatic IRβ. These findings suggest that the continuous administration of COC could cause insulin resistance with the prolongation of treatment.

Mineralocorticoid Receptor May Regulate Glucose Homeostasis through the Induction of Interleukin-6 and Glucagon-Like peptide-1 in Pancreatic Islets

Because the renin-angiotensin-aldosterone system influences glucose homeostasis, the mineralocorticoid receptor (MR) signal in pancreatic islets may regulate insulin response upon glucose load. Glucagon-like peptide-1 (GLP-1) production is stimulated by interleukin-6 (IL-6) in pancreatic α-cells. To determine how glucose homeostasis is regulated by interactions of MR, IL-6 and GLP-1 in islets, we performed glucose tolerance and histological analysis of islets in primary aldosteronism (PA) model rodents and conducted in vitro experiments using α-cell lines. We measured active GLP-1 concentration in primary aldosteronism (PA) patients before and after the administration of MR antagonist eplerenone. In PA model rodents, aldosterone decreased insulin-secretion and the islet/pancreas area ratio and eplerenone added on aldosterone (E+A) restored those with induction of IL-6 in α-cells. In α-cells treated with E+A, IL-6 and GLP-1 concentrations were increased, and anti-apoptotic signals were enhanced. The E+A-treatment also significantly increased MR and IL-6 mRNA and these upregulations were blunted by MR silencing using small interfering RNA (siRNA). Transcriptional activation of the IL-6 gene promoter by E+A-treatment required an intact MR binding element in the promoter. Active GLP-1 concentration was significantly increased in PA patients after eplerenone treatment. MR signal in α-cells may stimulate IL-6 production and increase GLP-1 secretion, thus protecting pancreatic β-cells and improving glucose homeostasis.

Aldosterone stimulation mediates cardiac metabolism remodeling via Sirt1/AMPK signaling in canine model

Aldosterone (Aldo), a pivotal hormone that is ubiquitously expressed in systemic tissues of mammals, is a crucial factor in the pathogenesis of cardiac disease. Accumulating evidence suggests that disturbances in cell energy metabolism are involved in increasing aldosterone levels. However, the precise mechanism underlying the impact of cardiac metabolic remodeling underlying aldosterone stimulation remains limited. In this work, we evaluated the underlying effect of aldosterone on regulating cardiac metabolism remodeling in a canine model. Fifteen beagle dogs were divided into a control group (n = 5), Aldo group (n = 5), and a group treated with spironolactone (SP), a mineralocorticoid receptor antagonist (n = 5), for 4 weeks. Blood pressure, electrocardiogram and respiratory parameters, H&E, Masson staining, ultrastructural changes, the adenosine triphosphate (ATP) and free fatty acid (FFA) levels of ventricular tissues, the level of mRNA, and the protein expression of key metabolic factors and regulators were assessed. The Sirt1/AMPK signaling pathway was significantly inhibited in the canine model of aldosterone stimulation, resulting in a reduction of the key downstream metabolic factors involved in glucose and fatty acid oxidation. The dysregulation of expression of key factors in glycogen metabolism led to glycogen deposition, an increase in FFA levels, a reduction in ATP levels, apoptosis, inflammatory cell infiltration, and mitochondrial damage in the ventricular myocardium. These effects were significantly restored by spironolactone. Aldosterone stimulation induced cardiac metabolic remodeling in ventricular cardiomyocytes possibly through the Sirt1/AMPK signaling pathway, implying that this pathway may provide a novel therapeutic target for cardiac metabolic remodeling.

Links between aldosterone excess and metabolic complications: A comprehensive review

Shortly after the first description of primary aldosteronism (PA) appeared in the 1950s by Jerome Conn, an association of the condition with diabetes mellitus was documented. However, a clear pathophysiological interrelationship linking the two entities has yet to be established. Nevertheless, so far, many mechanisms contributing to insulin resistance and dysregulation of glucose uptake have been described. At the same time, many observational studies have reported an increased prevalence of the metabolic syndrome (MetS) among patients with PA. Regarding the relationship between aldosterone levels and obesity, a vicious cycle of adipokine-induced aldosterone production and aldosterone adipogenic action may be further contributing to MetS manifestations in PA patients. However, whether aldosterone excess affects lipid metabolism is still under investigation. Also, recent findings of the coexistence of glucocorticoid excess in many cases of PA highlight the need for further studies to examine the presumed link between high aldosterone levels and various metabolic parameters. In the present review, our focus is to comprehensively present the spectrum of available research findings concerning the possible associations between aldosterone excess and metabolic alterations, including impaired glucose metabolism, insulin resistance and, consequently, diabetes, altered lipid metabolism and the development of fatty liver. In addition, the complex relationship between obesity and aldosterone is discussed in detail.

Inhibitors of Aldosterone Synthase

The mineralocorticoid aldosterone is an important regulator of blood pressure and electrolyte balance. However, excess aldosterone can be deleterious as a driver of inflammation, vascular remodeling and tissue fibrosis associated with cardiometabolic diseases. Mineralocorticoid receptor antagonists (MRA) and renin-angiotensin-aldosterone system (RAAS) antagonists are current clinical therapies used to antagonize deleterious effects of aldosterone in patients. MRAs compete with aldosterone for binding at its cognate receptor thereby limiting its effect while RAS antagonists reduce aldosterone levels indirectly by blocking the stimulatory effect of angiotensin. Both MRAs and RAS antagonists can result in incomplete inhibition of the harmful effects of excess aldosterone. Aldosterone synthase (AS) inhibitors (ASI) attenuate the production of aldosterone directly and have been proposed as an alternative to MRAs and RAS blockers. Cortisol synthase (CS) is an enzyme closely related to AS and responsible for generating the important glucocorticoid cortisol, required for maintaining critical metabolic and immune responses. The importance of selectivity against CS is shown by early examples of ASIs that were only modestly selective and as such, attenuated cortisol responses when evaluated in patients. Recently, next-generation, highly selective ASIs have been described and are presently being evaluated in the clinic as an alternative to angiotensin and MR antagonists for cardiometabolic disease. Herein we provide a brief review of the challenges associated with discovery of selective ASIs and the transition from the early compounds that paved the way toward the next-generation of highly selective ASIs currently under development.

Obesity as a Key Factor Underlying Idiopathic Hyperaldosteronism

CONTEXT

Recently, the relationship between primary aldosteronism (PA) and various metabolic disorders, including obesity, diabetes mellitus, and dyslipidemia, has been discussed. However, in PA, aldosterone-producing adenoma (APA) and idiopathic hyperaldosteronism (IHA) have different etiologies.

OBJECTIVE

Our objectives were to clarify differences in obesity and metabolic disorders between APA and IHA and to gain insight in the pathogenesis of IHA.

DESIGN, SETTING, AND PARTICIPANTS

This is a retrospective cross-sectional study. We assessed the PA database established by the multicenter Japan Primary Aldosteronism Study. For comparative analysis, data were also collected from 274 patients with essential hypertension (EHT).

MAIN OUTCOME MEASURES

We compared prevalences of obesity and metabolic disorders between patients with APA and patients with IHA. Comparisons with sex-, age-, and blood pressure-matched patients with EHT were also performed. Correlations between metabolic parameters and plasma aldosterone concentrations (PACs) in each subtype were analyzed.

RESULTS

Analysis of 516 patients with APA and 1015 patients with IHA revealed PACs were significantly higher in patients with APA than patients with IHA. By contrast, after we adjusted for clinical backgrounds, the prevalence of obesity was significantly higher in patients with IHA than in patients with APA or EHT. Although the prevalences of diabetes mellitus and dyslipidemia did not significantly differ between patients with IHA and patients with APA, triglyceride and HbA1c were significantly higher in patients with IHA than in patients with APA. There was no significant correlation between metabolic parameters and PACs in either subtype.

CONCLUSIONS

Patients with IHA tend to be obese despite lower PACs than in patients with APA. The present results suggest that obesity-related factors contribute to the pathogenesis of IHA.

Mitochondrial oxidative stress in obesity: role of the mineralocorticoid receptor

Obesity is a multifaceted, chronic, low-grade inflammation disease characterized by excess accumulation of dysfunctional adipose tissue. It is often associated with the development of cardiovascular (CV) disorders, insulin resistance and diabetes. Under pathological conditions like in obesity, adipose tissue secretes bioactive molecules called 'adipokines', including cytokines, hormones and reactive oxygen species (ROS). There is evidence suggesting that oxidative stress, in particular, the ROS imbalance in adipose tissue, may be the mechanistic link between obesity and its associated CV and metabolic complications. Mitochondria in adipose tissue are an important source of ROS and their dysfunction contributes to the pathogenesis of obesity-related type 2 diabetes. Mitochondrial function is regulated by several factors in order to preserve mitochondria integrity and dynamics. Moreover, the renin-angiotensin-aldosterone system is over-activated in obesity. In this review, we focus on the pathophysiological role of the mineralocorticoid receptor in the adipose tissue and its contribution to obesity-associated metabolic and CV complications. More specifically, we discuss whether dysregulation of the mineralocorticoid system within the adipose tissue may be the upstream mechanism and one of the early events in the development of obesity, via induction of oxidative stress and mitochondrial dysfunction, thus impacting on systemic metabolism and the CV system.

Aldosterone deficiency in mice burdens respiration and accentuates diet-induced hyperinsulinemia and obesity

Aldosterone synthase inhibitors (ASIs) should alleviate obesity-related cardiovascular and renal problems resulting partly from aldosterone excess, but their clinical use may have limitations. To improve knowledge for the use of ASIs, we investigated physiology in aldosterone synthase-knockout (ASKO) mice. On regular chow diet (CD), ASKO mice ate more and weighed less than WT mice, largely because they hyperventilated to eliminate acid as CO2. Replacing CD with high-fat diet (HFD) lessened the respiratory burden in ASKO mice, as did 12- to 15-hour fasting. The latter eliminated the genotype differences in respiratory workload and energy expenditure (EE). Thus, aldosterone deficiency burdened the organism more when the animals ate carbohydrate-rich chow than when they ate a HFD. Chronic HFD exposure further promoted hyperinsulinemia in ASKO mice that contributed to visceral fat accumulation accompanied by reduced lipolysis, thermogenic reprogramming, and the absence of weight-gain-related EE increases. Intracerebroventricular aldosterone supplementation in ASKO mice attenuated the HFD-induced hyperinsulinemia, but did not affect EE, suggesting that the presence of aldosterone increased the body's energetic efficiency, thus counteracting the EE-increasing effect of low insulin. ASIs may therefore cause acid-overload-induced respiratory burden and promote obesity. Their use in patients with preexisting renal and cardiopulmonary diseases might be contraindicated.

High glucose stimulates expression of aldosterone synthase (CYP11B2) and secretion of aldosterone in human adrenal cells

Aldosterone synthase is the key rate‐limiting enzyme in adrenal aldosterone production, and induction of its gene (CYP11B2) results in the progression of hypertension. As hypertension is a frequent complication among patients with diabetes, we set out to elucidate the link between diabetes mellitus and hypertension. We examined the effects of high glucose on CYP11B2 expression and aldosterone production using human adrenal H295R cells and a stable H295R cell line expressing a CYP11B2 5′‐flanking region/luciferase cDNA chimeric construct. d‐glucose (d‐glu), but not its enantiomer l‐glucose, dose dependently induced CYP11B2 transcription and mRNA expression. A high concentration (450 mg·dL⁻¹) of d‐glu time dependently induced CYP11B2 transcription and mRNA expression. Moreover, high glucose stimulated secretion of aldosterone into the media. Transient transfection studies using deletion mutants/nerve growth factor‐induced clone B (NGFIB) response element 1 (NBRE‐1) point mutant of CYP11B2 5′‐flanking region revealed that the NBRE‐1 element, known to be activated by transcription factors NGFIB and NURR1, was responsible for the high glucose‐mediated effect. High glucose also induced the mRNA expression of these transcription factors, especially that of NURR1, but NURR1 knockdown using its siRNA did not affect high glucose‐induced CYP11B2 mRNA expression. Taken together, it is speculated that high glucose may induce CYP11B2 transcription via the NBRE‐1 element in its 5′‐flanking region, resulting in the increase in aldosterone production although high glucose‐induced NURR1 is not directly involved in the effect. Additionally, glucose metabolism and calcium channels were found to be involved in the high glucose effect. Our observations suggest one possible explanation for the high incidence of hypertension in patients with diabetes.

Sodium-glucose cotransporter-2 inhibition and acidosis in patients with type 2 diabetes: a review of US FDA data and possible conclusions

Objective

To evaluate whether adverse event reports to the US Food and Drug Administration on incidents of ketoacidosis from use of sodium glucose cotransport inhibitors (SGLT2 inhibitors) provide insight into ways this new class of drugs is being prescribed with other antihyperglycemic agents; to examine possible mechanisms to explain ketoacidosis.

Design and methods

Reports of adverse events concerned to SGLT2 inhibitors, namely, empagliflozin, dapagliflozin, and canagliflozin were obtained under the Freedom of Information Act for 5 years ending in August 31, 2015. The data were evaluated for incidents of ketoacidosis by looking for keywords such as diabetic ketoacidosis, ketoacidosis, lactic acidosis, acidosis, and metabolic acidosis. Results were tabulated individually for empagliflozin (n=260 adverse event reports), dapagliflozin (n=520), and canagliflozin (n=2159). Adverse events were categorized according to age, gender, and insulin use.

Results

There were 46, 144, and 450 reports of ketoacidosis concerned with the use of empagliflozin, dapagliflozin, and canagliflozin, respectively. The use of SGLT2 inhibitors was not strictly limited to patients with type 2 diabetes but was cut across categories of insulin use, including a total of 172 cases of SGLT2-related ketoacidosis in individuals above the age of 40 who were not on insulin.

Conclusion

Further studies should focus to detect pleiotropic effects of SGLT2 inhibitors, particularly with other oral antihyperglycemic drugs or insulin. A review of the literature suggests that patients with type 2 diabetes with low C-peptide level may be at increased risk of ketoacidosis, particularly if they are on statins and diuretics due to hypokalemia and impaired release of insulin. More studies are warranted to further clarify these mechanisms.

Cytochrome P450 epoxygenase-derived epoxyeicosatrienoic acids contribute to insulin sensitivity in mice and in humans

AIMS/HYPOTHESIS

Insulin resistance is frequently associated with hypertension and type 2 diabetes. The cytochrome P450 (CYP) arachidonic acid epoxygenases (CYP2C, CYP2J) and their epoxyeicosatrienoic acid (EET) products lower blood pressure and may also improve glucose homeostasis. However, the direct contribution of endogenous EET production on insulin sensitivity has not been previously investigated. In this study, we tested the hypothesis that endogenous CYP2C-derived EETs alter insulin sensitivity by analysing mice lacking CYP2C44, a major EET producing enzyme, and by testing the association of plasma EETs with insulin sensitivity in humans.

METHODS

We assessed insulin sensitivity in wild-type (WT) and Cyp2c44 ^-/- mice using hyperinsulinaemic-euglycaemic clamps and isolated skeletal muscle. Insulin secretory function was assessed using hyperglycaemic clamps and isolated islets. Vascular function was tested in isolated perfused mesenteric vessels. Insulin sensitivity and secretion were assessed in humans using frequently sampled intravenous glucose tolerance tests and plasma EETs were measured by mass spectrometry.

RESULTS

Cyp2c44 ^-/- mice showed decreased glucose tolerance (639 ± 39.5 vs 808 ± 37.7 mmol/l × min for glucose tolerance tests, p = 0.004) and insulin sensitivity compared with WT controls (hyperinsulinaemic clamp glucose infusion rate average during terminal 30 min 0.22 ± 0.02 vs 0.33 ± 0.01 mmol kg^-1 min^-1 in WT and Cyp2c44 ^-/- mice respectively, p = 0.003). Although glucose uptake was diminished in Cyp2c44 ^-/- mice in vivo (gastrocnemius R_g 16.4 ± 2.0 vs 6.2 ± 1.7 μmol 100 g^-1 min^-1, p < 0.01) insulin-stimulated glucose uptake was unchanged ex vivo in isolated skeletal muscle. Capillary density was similar but vascular K_ATP-induced relaxation was impaired in isolated Cyp2c44 ^-/- vessels (maximal response 39.3 ± 6.5% of control, p < 0.001), suggesting that impaired vascular reactivity produces impaired insulin sensitivity in vivo. Similarly, plasma EETs positively correlated with insulin sensitivity in human participants.

CONCLUSIONS/INTERPRETATION

CYP2C-derived EETs contribute to insulin sensitivity in mice and in humans. Interventions to increase circulating EETs in humans could provide a novel approach to improve insulin sensitivity and treat hypertension.

Aldosterone excess may inhibit insulin secretion: A comparative study on glucose metabolism pre- and post-adrenalectomy in patients with primary aldosteronism

Conflicting data have been published on the effects of aldosterone excess on glucose metabolism. Specifically, there are limited data on whether adrenalectomy in patients with aldosterone-producing adenomas (APA) can improve glucose metabolism. In this study we evaluated changes in glucose metabolism, before and after surgery for APA. The subjects were 61 patients treated with unilateral adrenalectomy, localized by adrenal venous sampling. A 75g-oral glucose tolerance test (OGTT) was performed before and 1 year after adrenalectomy. Patients with diabetes mellitus or a serum cortisol level >3 μg/dL after a 1 mg dexamethasone suppression test, were excluded. Using the 75g-OGTT data, insulin secretion and insulin resistance (or sensitivity) indices were calculated. The results showed that immunoreactive insulin levels during the OGTT increased significantly after adrenalectomy, whereas plasma glucose levels, before and after surgery, were comparable. The insulinogenic index significantly increased after surgery (0.5 [0.4-0.8] to 0.8 [0.4-1.1], p < 0.001). The disposition index remained largely unchanged (806.2 [489.4-1,138.9] to 686.6 [479.4-922.1], p = 0.25). The homeostatic model assessment of insulin resistance increased significantly (1.0 [0.6-1.5] to 1.5 [1.0-2.2], p < 0.001) and the ISI_matsuda decreased significantly (6.9 [4.5-10.4] to 5.2 [3.4-7.9], p < 0.001). Changes in these indices were not correlated with changes in potassium and aldosterone levels before and after surgery. In conclusion, insulin secretion increased after adrenalectomy for APA, indicating that aldosterone excess inhibits insulin secretion. However, because of a parallel increase in insulin resistance, plasma glucose levels remained unchanged.

Aldosterone Synthase Inhibition Improves Glucose Tolerance in Zucker Diabetic Fatty (ZDF) Rats

Plasma aldosterone is elevated in type 2 diabetes and obesity in experimental and clinical studies and can act to inhibit both glucose-stimulated insulin secretion by the β-cell and insulin signaling. Currently mineralocorticoid receptor antagonism is the best characterized treatment to ameliorate aldosterone-mediated effects. A second alternative is inhibition of aldosterone synthase, an approach with protective effects on end-organ damage in heart or kidney in animal models. The effect of aldosterone synthase inhibition on metabolic parameters in type 2 diabetes is not known. Therefore, male Zucker diabetic fatty (ZDF) rats were treated for 11 weeks with the aldosterone synthase inhibitor FAD286, beginning at 7 weeks of age. Results were compared with the mineralocorticoid receptor antagonist eplerenone. Plasma aldosterone was abolished by FAD286 and elevated more than 9-fold by eplerenone. The area under the curve calculated from an oral glucose tolerance test (OGTT) was lower and overall insulin response during OGTT was increased by FAD286. In contrast, eplerenone elevated blood glucose levels and blunted insulin secretion during the OGTT. Fasting glucose was lowered and fasting insulin was increased by FAD286 in the prediabetic state. Glycated hemoglobin was lowered by FAD286, whereas eplerenone showed no effect. We conclude that aldosterone synthase inhibition, in contrast to mineralocorticoid receptor antagonism, has the potential for beneficial effects on metabolic parameters in type 2 diabetes.