Effects of acute glucocorticoid blockade on metabolic dysfunction in patients with Type 2 diabetes with and without fatty liver

Role of Glucocorticoids in Metabolic Dysfunction-Associated Steatotic Liver Disease

PURPOSE OF THE REVIEW

To summarize published data on the association between glucocorticoids and metabolic dysfunction-associated steatotic liver disease (MASLD), focusing on the possible pathophysiological links and related treatment considerations.

RECENT FINDINGS

Glucocorticoids, commonly used for managing many inflammatory and autoimmune diseases, may contribute to the development and progression of MASLD. Glucocorticoids may induce hyperglycemia and hyperinsulinemia, thus increasing systemic and hepatic insulin resistance, a hallmark of MASLD pathogenesis. Furthermore, glucocorticoids increase adipose tissue lipolysis, and hepatic de novo lipogenesis and decrease hepatic fatty acid β-oxidation, thus promoting MASLD development. Preclinical evidence also suggests that glucocorticoids may adversely affect hepatic inflammation and fibrosis. 11beta-hydroxysteroid dehydrogenase type 1 (11β-HSD1) and 5α-reductase are implicated in the link between glucocorticoids and MASLD, the former enzyme increasing and the latter reducing the glucocorticoid action on the liver. Treatment considerations exist due to the pathogenic link between glucocorticoids and MASLD. Since iatrogenic hypercortisolism is common, glucocorticoids should be used at the minimum daily dose to control the subjective disease. Furthermore, the pharmacologic inhibition of 11β-HSD1 has provided favorable results in MASLD, both in preclinical studies and early MASH clinical trials. Glucocorticoids are closely linked to MASLD pathophysiology, with specific clinical and therapeutic implications.

Glucocorticoid Receptors Drive Breast Cancer Cell Migration and Metabolic Reprogramming via PDK4

Corticosteroids act on the glucocorticoid receptor (GR; NR3C1) to resolve inflammation and are routinely prescribed to breast cancer patients undergoing chemotherapy treatment to alleviate side effects. Triple-negative breast cancers (TNBCs) account for 15% to 20% of diagnoses and lack expression of estrogen and progesterone receptors as well as amplified HER2, but they often express high GR levels. GR is a mediator of TNBC progression to advanced metastatic disease; however, the mechanisms underpinning this transition to more aggressive behavior remain elusive. We previously showed that tissue/cellular stress (hypoxia, chemotherapies) as well as factors in the tumor microenvironment (transforming growth factor β [TGF-β], hepatocyte growth factor [HGF]) activate p38 mitogen-activated protein kinase (MAPK), which phosphorylates GR on Ser134. In the absence of ligand, pSer134-GR further upregulates genes important for responses to cellular stress, including key components of the p38 MAPK pathway. Herein, we show that pSer134-GR is required for TNBC metastatic colonization to the lungs of female mice. To understand the mechanisms of pSer134-GR action in the presence of GR agonists, we examined glucocorticoid-driven transcriptomes in CRISPR knock-in models of TNBC cells expressing wild-type or phospho-mutant (S134A) GR. We identified dexamethasone- and pSer134-GR-dependent regulation of specific gene sets controlling TNBC migration (NEDD9, CSF1, RUNX3) and metabolic adaptation (PDK4, PGK1, PFKFB4). TNBC cells harboring S134A-GR displayed metabolic reprogramming that was phenocopied by pyruvate dehydrogenase kinase 4 (PDK4) knockdown. PDK4 knockdown or chemical inhibition also blocked cancer cell migration. Our results reveal a convergence of GR agonists (ie, host stress) with cellular stress signaling whereby pSer134-GR critically regulates TNBC metabolism, an exploitable target for the treatment of this deadly disease.

Biochemical and Radiological Changes in Liver Steatosis Following Mifepristone Treatment in Patients With Hypercortisolism

Background

Case Report

Discussion

Conclusion

Mifepristone Improves Adipose Tissue Insulin Sensitivity in Insulin Resistant Individuals

BACKGROUND

Increased tissue cortisol availability has been implicated in abnormal glucose and fat metabolism in patients with obesity, metabolic syndrome, and type 2 diabetes (T2DM). Our objective was to evaluate whether blockade of glucocorticoid receptor (GR) with mifepristone ameliorates insulin resistance (IR) in overweight/obese subjects with glucose intolerance.

METHODS

We conducted a randomized, double-blinded, placebo-controlled, crossover study in overweight/obese individuals (n = 16, 44% female) with prediabetes or mild T2DM but not clinical hypercortisolism. Mifepristone (50 mg every 6 h) or placebo was administered for 9 days, followed by crossover to the other treatment arm after a washout period of 6 to 8weeks. At baseline and following each treatment, oral glucose tolerance test (OGTT) and frequently sampled intravenous glucose tolerance test (FSIVGTT) were performed. Insulin sensitivity was measured using FSIVGTT [primary outcome: insulin sensitivity index (SI)] and OGTT [Matsuda index (MI) and oral glucose insulin sensitivity index (OGIS)]. Hepatic and adipose insulin resistance were assessed using hepatic insulin resistance index (HIRI), and adipose tissue insulin sensitivity index (Adipo-SI) and adipo-IR, derived from the FSIVGTT.

RESULTS

Mifepristone administration did not alter whole-body glucose disposal indices of insulin sensitivity (SI, MI, and OGIS). GR blockade significantly improved Adipo-SI (61.7 ± 32.9 vs 42.8 ± 23.9; P = 0.002) and reduced adipo-IR (49.9 ± 45.9 vs 65.5 ± 43.8; P = 0.004), and HIRI (50.2 ± 38.7 vs 70.0 ± 44.3; P = 0.08). Mifepristone increased insulin clearance but did not affect insulin secretion or β-cell glucose sensitivity.

CONCLUSION

Short-term mifepristone administration improves adipose and hepatic insulin sensitivity among obese individuals with hyperglycemia without hypercortisolism.

FX5 as a non-steroidal GR antagonist improved glucose homeostasis in type 2 diabetic mice via GR/HNF4α/miR-122-5p pathway

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disease characterized by glucose metabolic disorders, and gluconeogenesis inhibiting is a promisingly therapeutic strategy for T2DM. Glucocorticoid receptor (GR) is tightly implicated in the regulation of gluconeogenesis, although the underlying mechanism remains obscure. Here, we discovered that small molecule, 5-chloro-N-[4-chloro-3-(trifluoromethyl)phenyl]thiophene-2-sulfonamide (FX5) as a new non-steroidal GR antagonist efficiently ameliorated glucose homeostasis in db/db and HFD/STZ-induced T2DM mice. The mechanism underlying the suppression of FX5 against gluconeogenesis was highly investigated. FX5 suppressed gluconeogenetic genes G6Pase and PEPCK in mouse primary hepatocytes and liver tissues of T2DM mice. Results of mammalian one-hybrid and transactivation as well as nuclear translocation assays totally evaluated the antagonistic features of FX5 against GR. Moreover, siRNA and overexpression related assays verified that FX5 alleviated gluconeogenesis either directly by antagonizing GR or indirectly through GR/HNF4α/miR122-5p signaling pathway. Our work has presented a new mode for GR antagonist in the regulation of gluconeogenesis, which is expected to highlight the potential of FX5 in the treatment of T2DM.

Correlation among body composition and metabolic regulation in a male mouse model of Cushing's syndrome

Glucocorticoids play a critical role in the regulation of homeostasis, including metabolism. In patients with Cushing's syndrome, chronic glucocorticoid excess disrupts physiological internal milieu, resulting in central obesity, muscle atrophy, fatty liver, and insulin resistance. However, the relationship among various metabolic effects of glucocorticoids remains unknown. In the present study, we studied a male mouse model of Cushing's syndrome and indicated that glucocorticoid excess alters metabolic phenotype and body composition involving possible communication among skeletal muscle, liver, and adipose tissue.

Association Between Cortisol, Insulin Resistance and Zinc in Obesity: a Mini-Review

Adipose tissue is considered an endocrine organ and its excess compromises the immune response and the metabolism of hormones and nutrients. Furthermore, visceral fat accumulation contributes to increased cortisol synthesis, which in turn induces metallothionein and Zip14 expression, which are proteins that contribute to reducing plasma zinc levels. Zinc plays a critical role in the secretion and signaling of insulin. Changes in the biochemical parameters of zinc, as observed in individuals who are obese, contribute to the manifestation of related disorders such as insulin resistance. Thus, the purpose of this review is to provide an update on the current information on the relationship between cortisol, zinc, and insulin resistance in obesity. The data in the literature provide evidence that cortisol affects zinc metabolism, and indicate possible repercussions on insulin signaling that might contribute to the development of resistance to the actions of insulin in obesity.

Role of Hepatic Glucocorticoid Receptor in Metabolism in Models of 5αR1 Deficiency in Male Mice

Inhibition of 5α-reductases impairs androgen and glucocorticoid metabolism and induces insulin resistance in humans and rodents. The contribution of hepatic glucocorticoids to these adverse metabolic changes was assessed using a liver-selective glucocorticoid receptor (GR) antagonist, A-348441. Mice lacking 5α-reductase 1 (5αR1-KO) and their littermate controls were studied during consumption of a high-fat diet, with or without A-348441(120 mg/kg/d). Male C57BL/6 mice (age, 12 weeks) receiving dutasteride (1.8 mg/kg/d)) or vehicle with consumption of a high-fat diet, with or without A-348441, were also studied. In the 5αR1-KO mice, hepatic GR antagonism improved diet-induced insulin resistance but not more than that of the controls. Liver steatosis was not affected by hepatic GR antagonism in either 5αR1KO mice or littermate controls. In a second model of 5α-reductase inhibition using dutasteride and hepatic GR antagonism with A-348441 attenuated the excess weight gain resulting from dutasteride (mean ± SEM, 7.03 ± 0.5 vs 2.13 ± 0.4 g; dutasteride vs dutasteride plus A-348441; P < 0.05) and normalized the associated hyperinsulinemia after glucose challenge (area under the curve, 235.9 ± 17 vs 329.3 ± 16 vs 198.4 ± 25 ng/mL/min; high fat vs high fat plus dutasteride vs high fat plus dutasteride plus A-348441, respectively; P < 0.05). However, A-348441 again did not reverse dutasteride-induced liver steatosis. Thus, overall hepatic GR antagonism improved the insulin resistance but not the steatosis induced by a high-fat diet. Moreover, it attenuated the excessive insulin resistance caused by pharmacological inhibition of 5α-reductases but not genetic disruption of 5αR1. The use of dutasteride might increase the risk of type 2 diabetes mellitus and reduced exposure to glucocorticoids might be beneficial.

Estrogen Deficiency Promotes Hepatic Steatosis via a Glucocorticoid Receptor-Dependent Mechanism in Mice

Glucocorticoids (GCs) are master regulators of systemic metabolism. Intriguingly, Cushing’s syndrome, a disorder of excessive GCs, phenocopies several menopause-induced metabolic pathologies. Here, we show that the glucocorticoid receptor (GR) drives steatosis in hypogonadal female mice because hepatocyte-specific GR knockout mice are refractory to developing ovariectomy-induced steatosis. Intriguingly, transcriptional profiling revealed that ovariectomy elicits hepatic GC hypersensitivity globally. Hypogonadism-induced GC hypersensitivity results from a loss of systemic but not hepatic estrogen (E2) signaling, given that hepatocyte-specific E2 receptor deletion does not confer GC hypersensitivity. Mechanistically, enhanced chromatin recruitment and ligand-dependent hyperphosphorylation of GR underlie ovariectomy-induced glucocorticoid hypersensitivity. The dysregulated glucocorticoid-mediated signaling present in hypogonadal females is a product of increased follicle-stimulating hormone (FSH) production because FSH treatment in ovary-intact mice recapitulates glucocorticoid hypersensitivity similar to hypogonadal female mice. Our findings uncover a regulatory axis between estradiol, FSH, and hepatic glucocorticoid receptor signaling that, when disrupted, as in menopause, promotes hepatic steatosis.

Silencing of maternal hepatic glucocorticoid receptor is essential for normal fetal development in mice

Excessive or chronic stress can lead to a variety of diseases due to aberrant activation of the glucocorticoid receptor (GR), a ligand activated transcription factor. Pregnancy represents a particular window of sensitivity in which excessive stress can have adverse outcomes, particularly on the developing fetus. Here we show maternal hepatic stress hormone responsiveness is diminished via epigenetic silencing of the glucocorticoid receptor during pregnancy. Provocatively, reinstallation of GR to hepatocytes during pregnancy by adeno-associated viral transduction dysregulates genes involved in proliferation, resulting in impaired pregnancy-induced hepatomegaly. Disruption of the maternal hepatic adaptation to pregnancy results in in utero growth restriction (IUGR). These data demonstrate pregnancy antagonizes the liver-specific effects of stress hormone signaling in the maternal compartment to ultimately support the healthy development of embryos.

Substantial Metabolic Activity of Human Brown Adipose Tissue during Warm Conditions and Cold-Induced Lipolysis of Local Triglycerides

Current understanding of in vivo human brown adipose tissue (BAT) physiology is limited by a reliance on positron emission tomography (PET)/computed tomography (CT) scanning, which has measured exogenous glucose and fatty acid uptake but not quantified endogenous substrate utilization by BAT. Six lean, healthy men underwent ¹⁸fluorodeoxyglucose-PET/CT scanning to localize BAT so microdialysis catheters could be inserted in supraclavicular BAT under CT guidance and in abdominal subcutaneous white adipose tissue (WAT). Arterial and dialysate samples were collected during warm (∼25°C) and cold exposure (∼17°C), and blood flow was measured by ¹³³xenon washout. During warm conditions, there was increased glucose uptake and lactate release and decreased glycerol release by BAT compared with WAT. Cold exposure increased blood flow, glycerol release, and glucose and glutamate uptake only by BAT. This novel use of microdialysis reveals that human BAT is metabolically active during warm conditions. BAT activation substantially increases local lipolysis but also utilization of other substrates such as glutamate.

Stress and Obesity: Are There More Susceptible Individuals?

PURPOSE OF REVIEW

Stress has long been suspected to be interrelated to (abdominal) obesity. However, interindividual differences in this complex relationship exist. We suggest that the extent of glucocorticoid action partly explains these interindividual differences. We provide latest insights with respect to multiple types of stressors.

RECENT FINDINGS

Increased long-term cortisol levels, as measured in scalp hair, are strongly related to abdominal obesity and to specific mental disorders. However, not all obese patients have elevated cortisol levels. Possibly, the interindividual variation in glucocorticoid sensitivity, which is partly genetically determined, may lead to higher vulnerability to mental or physical stressors. Other evidence for the important role for increased glucocorticoid action is provided by recent studies investigating associations between body composition and local and systemic corticosteroids. Stress may play a major role in the development and maintenance of obesity in individuals who have an increased glucocorticoid exposure or sensitivity. These insights may lead to more effective and individualized obesity treatment strategies.

Fat-brain connections: Adipocyte glucocorticoid control of stress and metabolism

Glucocorticoids act via multiple mechanisms to mobilize energy for maintenance and restoration of homeostasis. In adipose tissue, glucocorticoids can promote lipolysis and facilitate adipocyte differentiation/growth, serving both energy-mobilizing and restorative processes during negative energy balance. Recent data suggest that adipose-dependent feedback may also be involved in regulation of stress responses. Adipocyte glucocorticoid receptor (GR) deletion causes increased HPA axis stress reactivity, due to a loss of negative feedback signals into the CNS. The fat-to-brain signal may be mediated by neuronal mechanisms, release of adipokines or increased lipolysis. The ability of adipose GRs to inhibit psychogenic as well as metabolic stress responses suggests that (1) feedback regulation of the HPA axis occurs across multiple bodily compartments, and (2) fat tissue integrates psychogenic stress signals. These studies support a link between stress biology and energy metabolism, a connection that has clear relevance for numerous disease states and their comorbidities.

Effects of Mifepristone on Nonalcoholic Fatty Liver Disease in a Patient with a Cortisol-Secreting Adrenal Adenoma

Cushing syndrome (CS), a complex, multisystemic condition resulting from prolonged exposure to cortisol, is frequently associated with nonalcoholic fatty liver disease (NAFLD). In patients with adrenal adenoma(s) and NAFLD, it is essential to rule out coexisting endocrine disorders like CS, so that the underlying condition can be properly addressed. We report a case of a 49-year-old woman with a history of hypertension, prediabetes, dyslipidemia, biopsy-confirmed steatohepatitis, and benign adrenal adenoma, who was referred for endocrine work-up for persistent weight gain. Overt Cushing features were absent. Biochemical evaluation revealed nonsuppressed cortisol on multiple 1-mg dexamethasone suppression tests, suppressed adrenocorticotropic hormone, and low dehydroepiandrosterone sulfate. The patient initially declined surgery and was treated with mifepristone, a competitive glucocorticoid receptor antagonist. In addition to improvements in weight and hypertension, substantial reductions in her liver enzymes were noted, with complete normalization by 20 weeks of therapy. This case suggests that autonomous cortisol secretion from adrenal adenoma(s) could contribute to the metabolic and liver abnormalities in patients with NAFLD. In conclusion, successful management of CS with mifepristone led to marked improvement in the liver enzymes of a patient with long-standing NAFLD.

Acute physiological effects of glucocorticoids on fuel metabolism in humans are permissive but not direct

BACKGROUND AND AIMS

The effects of glucocorticoids on fuel metabolism are complex. Acute glucocorticoid excess promotes lipolysis but chronic glucocorticoid excess causes visceral fat accumulation. We hypothesized that interactions between cortisol and insulin and adrenaline account for these conflicting results. We tested the effect of cortisol on lipolysis and glucose production with and without insulin and adrenaline in humans both in vivo and in vitro.

MATERIALS AND METHODS

A total of 20 healthy men were randomized to low and high insulin groups (both n = 10). Subjects attended on 3 occasions and received low (c. 150 nM), medium (c. 400 nM) or high (c. 1400 nM) cortisol infusion in a randomized crossover design. Deuterated glucose and glycerol were infused intravenously along with a pancreatic clamp (somatostatin with replacement of glucagon, insulin and growth hormone) and adrenaline. Subcutaneous adipose tissue was obtained for analysis. In parallel, the effect of cortisol on lipolysis was tested in paired primary cultures of human subcutaneous and visceral adipocytes.

RESULTS

In vivo, high cortisol increased lipolysis only in the presence of high insulin and/or adrenaline but did not alter glucose kinetics. High cortisol increased adipose mRNA levels of ATGL, HSL and CGI-58 and suppressed G0S2. In vitro, high cortisol increased lipolysis in the presence of insulin in subcutaneous, but not visceral, adipocytes.

CONCLUSIONS

The acute lipolytic effects of cortisol require supraphysiological concentrations, are dependent on insulin and adrenaline and are observed only in subcutaneous adipose tissue. The resistance of visceral adipose tissue to cortisol's lipolytic effects may contribute to the central fat accumulation observed with chronic glucocorticoid excess.

The Functional and Clinical Significance of the 24-Hour Rhythm of Circulating Glucocorticoids

Adrenal glucocorticoids are major modulators of multiple functions, including energy metabolism, stress responses, immunity, and cognition. The endogenous secretion of glucocorticoids is normally characterized by a prominent and robust circadian (around 24 hours) oscillation, with a daily peak around the time of the habitual sleep-wake transition and minimal levels in the evening and early part of the night. It has long been recognized that this 24-hour rhythm partly reflects the activity of a master circadian pacemaker located in the suprachiasmatic nucleus of the hypothalamus. In the past decade, secondary circadian clocks based on the same molecular machinery as the central master pacemaker were found in other brain areas as well as in most peripheral tissues, including the adrenal glands. Evidence is rapidly accumulating to indicate that misalignment between central and peripheral clocks has a host of adverse effects. The robust rhythm in circulating glucocorticoid levels has been recognized as a major internal synchronizer of the circadian system. The present review examines the scientific foundation of these novel advances and their implications for health and disease prevention and treatment.

Glucocorticoids Acutely Increase Brown Adipose Tissue Activity in Humans, Revealing Species-Specific Differences in UCP-1 Regulation

The discovery of brown adipose tissue (BAT) in adult humans presents a new therapeutic target for metabolic disease; however, little is known about the regulation of human BAT. Chronic glucocorticoid excess causes obesity in humans, and glucocorticoids suppress BAT activation in rodents. We tested whether glucocorticoids regulate BAT activity in humans. In vivo, the glucocorticoid prednisolone acutely increased (18)fluorodeoxyglucose uptake by BAT (measured using PET/CT) in lean healthy men during mild cold exposure (16°C-17°C). In addition, prednisolone increased supraclavicular skin temperature (measured using infrared thermography) and energy expenditure during cold, but not warm, exposure in lean subjects. In vitro, glucocorticoids increased isoprenaline-stimulated respiration and UCP-1 in human primary brown adipocytes, but substantially decreased isoprenaline-stimulated respiration and UCP-1 in primary murine brown and beige adipocytes. The highly species-specific regulation of BAT function by glucocorticoids may have important implications for the translation of novel treatments to activate BAT to improve metabolic health.

Aromatase Inhibition Reduces Insulin Sensitivity in Healthy Men

CONTEXT

Deficiency of aromatase, the enzyme that catalyzes the conversion of androgens to estrogens, is associated with insulin resistance in humans and mice.

OBJECTIVE

We hypothesized that pharmacological aromatase inhibition results in peripheral insulin resistance in humans.

DESIGN

This was a double-blind, randomized, controlled, crossover study.

SETTING

The study was conducted at a clinical research facility.

PARTICIPANTS

Seventeen healthy male volunteers (18-50 y) participated in the study.

INTERVENTION

The intervention included oral anastrozole (1 mg daily) and placebo, each for 6 weeks with a 2-week washout period.

MAIN OUTCOME MEASURE

Glucose disposal and rates of lipolysis were measured during a stepwise hyperinsulinemic euglycemic clamp. Data are mean (SEM).

RESULTS

Anastrozole therapy resulted in significant estradiol suppression (59.9 ± 3.6 vs 102.0 ± 5.7 pmol/L, P = < .001) and a more modest elevation of total T (25.8 ± 1.2 vs 21.4 ± 0.7 nmol/L, P = .003). Glucose infusion rate, during the low-dose insulin infusion, was lower after anastrozole administration (12.16 ± 1.33 vs 14.15 ± 1.55 μmol/kg·min, P = .024). No differences in hepatic glucose production or rate of lipolysis were observed.

CONCLUSION

Aromatase inhibition reduces insulin sensitivity, with respect to peripheral glucose disposal, in healthy men. Local generation and action of estradiol, at the level of skeletal muscle, is likely to be an important determinant of insulin sensitivity.

Glucocorticoids and non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is the hepatic manifestation of the global obesity and metabolic disease epidemic and is rapidly becoming the leading cause of liver cirrhosis and indication for liver transplantation worldwide. The hallmark pathological finding in NAFLD is excess lipid accumulation within hepatocytes, but it is a spectrum of disease ranging from benign hepatic steatosis to steatohepatitis through to fibrosis, cirrhosis and risk of hepatocellular carcinoma. The exact pathophysiology remains unclear with a multi-hit hypothesis generally accepted as being required for inflammation and fibrosis to develop after initial steatosis. Glucocorticoids have been implicated in the pathogenesis of NAFLD across all stages. They have a diverse array of metabolic functions that have the potential to drive NAFLD acting on both liver and adipose tissue. In the fasting state, they are able to mobilize lipid, increasing fatty acid delivery and in the fed state can promote lipid accumulation. Their action is controlled at multiple levels and in this review will outline the evidence base for the role of GCs in the pathogenesis of NAFLD from cell systems, rodent models and clinical studies and describe interventional strategies that have been employed to modulate glucocorticoid action as a potential therapeutic strategy.

Aberrant REDD1-mTORC1 responses to insulin in skeletal muscle from Type 2 diabetics

The objective of this study was to establish whether alterations in the REDD1-mTOR axis underlie skeletal muscle insensitivity to insulin in Type 2 diabetic (T2D), obese individuals. Vastus lateralis muscle biopsies were obtained from lean, control and obese, T2D subjects under basal and after a 2-h hyperinsulinemic (40 mU·m(-2)·min(-1))-euglycemic (5 mM) clamp. Muscle lysates were examined for total REDD1, and phosphorylated Akt, S6 kinase 1 (S6K1), 4E-BP1, ERK1/2, and MEK1/2 via Western blot analysis. Under basal conditions [(-) insulin], T2D muscle exhibited higher S6K1 and ERK1/2 and lower 4E-BP1 phosphorylation (P < 0.05), as well as elevations in blood cortisol, glucose, insulin, glycosylated hemoglobin (P < 0.05) vs. lean controls. Following insulin infusion, whole body glucose disposal rates (GDR; mg/kg/min) were lower (P < 0.05) in the T2D vs. the control group. The basal-to-insulin percent change in REDD1 expression was higher (P < 0.05) in muscle from the T2D vs. the control group. Whereas, the basal-to-insulin percent change in muscle Akt, S6K1, ERK1/2, and MEK1/2 phosphorylation was significantly lower (P < 0.05) in the T2D vs. the control group. Findings from this study propose a REDD1-regulated mechanism in T2D skeletal muscle that may contribute to whole body insulin resistance and may be a target to improve insulin action in insulin-resistant individuals.

Impact of long-term steroid therapy on epicardial and pericardial fat deposition: a cardiac MRI study

BACKGROUND

Increased cardiac fat has been identified as a risk factor for coronary artery disease. Metabolic syndrome is associated with increased cardiac fat deposition. Steroids are known to imitate some effects of metabolic syndrome and are frequently used in patients with rheumatic disorders. Primary aim was to evaluate the impact of long-term steroid use on cardiac fat deposition in patients with rheumatic disorders. In addition, we sought to investigate if this effect might be dose-dependent.

METHODS

Patients were enrolled as follows: (1) rheumatic disorder; and (2) long-term steroid therapy, and (3) underwent cardiovascular magnetic resonance (CMR) imaging. Patients were stratified in a high-dose (>7.5 mg prednisone equivalent/day for at least 6 months) and a low-dose steroid group (<7.5 mg prednisone equivalent/day) and compared to steroid-naïve controls without rheumatic disorders.

RESULTS

122 patients were included (n = 61 steroid patients, n = 61 controls). N = 36 were classified as high-dose, n = 25 as low-dose steroid group. Steroid patients showed larger epicardial 5.7 [3.5-9.1] cm(2) and pericardial 13.0 [6.1-26.8] cm(2) areas of fat than controls 4.2 [1.3-5.8] cm(2)/6.4 [1.6-15.4] cm(2), p < 0.001, p < 0.01, respectively. High-dose steroid patients had more epi- and pericardial fat both than controls: 7.2 [4.2-11.1] cm(2) vs. 4.4 [1.0-6.0] cm(2), p < 0.001; 18.6 [8.9-38.2] cm(2) vs. 10.7 [4.7-26.8] cm(2), p < 0.05, and patients in the low-dose steroid group (p < 0.01, p < 0.001, respectively).

CONCLUSION

The present data suggest increased cardiac fat deposition in steroid-treated patients with rheumatic disorders. Furthermore, this accumulation of cardiac fat seems to be dose-dependent, pointing towards a cumulative effect of steroids.

Cortisol dysregulation in obesity-related metabolic disorders

PURPOSE OF REVIEW

The present review highlights recent investigations in the prior 18 months focusing on the role of dysregulated cortisol physiology in obesity as a potential modifiable mechanism in the pathogenesis of obesity-related cardiometabolic disorders.

RECENT FINDINGS

Given the clinical resemblance of obesity-related metabolic disorders with the Cushing's syndrome, new studies have investigated the intracellular regulation and metabolism of cortisol, new measurements of cortisol in scalp hair as a tool for long-term exposure to cortisol, and the cortisol-mineralocorticoid receptor pathway. Thus, current and future pharmacological interventions in obesity may include specific inhibition of steroidogenic and regulatory enzymes as well as antagonists of the mineralocorticoid and glucocorticoid receptors.

SUMMARY

The understanding of how adrenal function is challenged by the interplay of our genetic and environmental milieu has highlighted the importance of inappropriate cortisol regulation in cardiometabolic disorders. Increased adipose tissue in obesity is associated with hypothalamic-pituitary-adrenal axis overactivation, increased cortisol production at the local tissue level, and probably higher mineralocorticoid receptor activation in certain tissues.