Glucocorticoids produce whole body insulin resistance with changes in cardiac metabolism

Effects of prenatal dexamethasone exposure on adult C57BL/6J mouse metabolism and oxidative stress

Prenatal glucocorticoid exposure has been shown to alter hypothalamic-pituitary-adrenal axis function resulting in altered fetal development that can persist through adulthood. Fetal exposure to excess dexamethasone, a synthetic glucocorticoid, has been shown to alter adult behaviour and metabolism. This study investigated the effects prenatal dexamethasone exposure had on adult offspring cardiac and liver metabolism and oxidative stress. Pregnant C57BL/6 mice received a dose of 0.4 mg/kg dexamethasone on gestational days 15-17. Once pups were approximately 7 months old, glucose uptake was determined using positron emission tomography and insulin resistance (IR) was determined by homeostatic model assessment (HOMA) IR calculation. Oxidative stress was assessed by measuring 4-hydroxynonenal protein adduct formation and total reactive oxygen species. Female dexamethasone group had significantly increased glucose uptake when insulin stimulated compared to vehicle-treated mice. HOMA IR revealed no evidence of IR in either male or female offspring. There was also no change in oxidative stress markers in either cardiac or liver tissues of male or female offspring. These data suggest that prenatal dexamethasone exposure in male mice does not alter oxidative stress or metabolism. However, prenatal dexamethasone exposure increased glucocorticoids, cardiac glucose uptake, and pAkt signaling in female heart tissues in adult mice, suggesting there are sex differences in prenatal dexamethasone exposure.

The Role of Pro-Opiomelanocortin Derivatives in the Development of Type 2 Diabetes-Associated Myocardial Infarction: Possible Links with Prediabetes

Myocardial infarction is a major contributor to CVD-related mortality. T2DM is a risk factor for MI. Stress activates the HPA axis, SNS, and endogenous OPS. These POMC derivatives increase the blood glucose and cardiovascular response by inhibiting the PI3K/AkT insulin signaling pathway and increasing cardiac contraction. Opioids regulate the effect of the HPA axis and SNS and they are cardioprotective. The chronic activation of the stress response may lead to insulin resistance, cardiac dysfunction, and MI. Stress and T2DM, therefore, increase the risk of MI. T2DM is preceded by prediabetes. Studies have shown that prediabetes is associated with an increased risk of MI because of inflammation, hyperlipidemia, endothelial dysfunction, and hypertension. The HPA axis is reported to be dysregulated in prediabetes. However, the SNS and the OPS have not been explored during prediabetes. The effect of prediabetes on POMC derivatives has yet to be fully explored and understood. The impact of stress and prediabetes on the cardiovascular response needs to be investigated. This study sought to review the potential impact of prediabetes on the POMC derivatives and pathways that could lead to MI.

Extracellular macrophage migration inhibitory factor (MIF) downregulates adipose hormone-sensitive lipase (HSL) and contributes to obesity

Attenuation of adipose hormone sensitive lipase (HSL) may impair lipolysis and exacerbate obesity. We investigate the role of cytokine, macrophage migration inhibitory factor (MIF) in regulating adipose HSL and adipocyte hypertrophy. Extracellular MIF downregulates HSL in an autocrine fashion, by activating the AMPK/JNK signaling pathway upon binding to its membrane receptor, CD74. WT mice fed high fat diet (HFD), as well as mice overexpressing MIF, both had high circulating MIF levels and showed suppression of HSL during the development of obesity. Blocking the extracellular action of MIF by a neutralizing MIF antibody significantly reduced obesity in HFD mice. Interestingly, intracellular MIF binds with COP9 signalosome subunit 5 (Csn5) and JNK, which leads to an opposing effect to inhibit JNK phosphorylation. With global MIF deletion, adipocyte JNK phosphorylation increased, resulting in decreased HSL expression, suggesting that the loss of MIF's intracellular inhibitory action on JNK was dominant in Mif-/- mice. Adipose tissue from Mif-/- mice also exhibited higher Akt and lower PKA phosphorylation following HFD feeding compared with WT, which may contribute to the downregulation of HSL activation during more severe obesity. Both intracellular and extracellular MIF have opposing effects to regulate HSL, but extracellular actions predominate to downregulate HSL and exacerbate the development of obesity during HFD.

Effects of grape seed proanthocyanidin extract on side effects of high-dose methylprednisolone administration in male rats

In this study, we investigated the effects of grape seed proanthocyanidin extract (GSPE) against the side effects of high-dose administration of methylprednisolone (MP) in male rats. A total of 32 adult Wistar male albino rats were divided into four groups: (1) control (CON), received standard food only; (2) MP, received standard food + intraperitoneal injection of 60 mg/kg MP on day 7; (3) GSPE, received standard food + 200 mg/kg/day GSPE; and (4) MP + GSPE, received standard food + 200 mg/kg/day of GSPE + intraperitoneal injection of 60 mg/kg MP on day 7. All animals in the GSPE and GSPE + MP groups were treated once a day by oral gavage for 14 consecutive days. The feed intake of rats in the MP and MP + GSPE groups decreased significantly by 24.14% and 13.52%, respectively (p < 0.05). Administration of MP resulted in significant increases in serum concentrations of blood urea nitrogen (p < 0.001), glucose (p < 0.01), alkaline phosphatase, and adrenocorticotropic hormone (p < 0.05). High-dose MP administration significantly reduced catalase (p < 0.001) and glutathione peroxidase (p < 0.05) concentrations in the liver and kidney tissues of rats, while glutathione concentrations were only reduced in liver tissue (p < 0.05). The expression levels of Bcl-2 and TNF-α in liver, kidney, and testicular tissue were significantly increased, while the expression levels of caspase-3 were reduced (p < 0.001). Furthermore, sperm concentration was significantly affected by GSPE in rats induced by high-dose MP, and sperm loss was significantly reduced in MP + GSPE (p < 0.05). These findings suggest that GSPE could be useful as a supplement to alleviate MP-induced toxicity in rats.

Exercise Prevents Glucocorticoid-Induced Myocardial 4-Hydroxynonenal Production

PURPOSE

Long-term administration of glucocorticoids (GCs) increases myocardial oxidative stress. 4-Hydroxynonenal (4-HNE) protein adducts, a marker of oxidative damage, have been associated with several cardiovascular diseases, including atherosclerosis, cardiac hypertrophy, cardiomyopathy, and ischemia-reperfusion injury. Exercise training has been shown to have a protective effect on the heart by lowering the level of oxidative stress in cardiomyocytes. Therefore, we aimed to investigate the effect of long-term dexamethasone treatment and exercise training on myocardial 4-HNE levels.

METHODS

Twenty-four female Wistar albino rats were assigned to sedentary control-saline treated (C, n = 8), sedentary-dexamethasone treated (D, n = 8), and exercise training-dexamethasone treated (DE, n = 8) groups. Daily dexamethasone was injected for 28 days at a 1 mg kg-1 dose, while C animals were injected with the same volume of saline subcutaneously. DE animals underwent an exercise training protocol of 60 min/day, 5 days a week, at 25 m/min-1 (0% grade) for 28 days. Left ventricular 4-HNE, Hsp72 levels, and pHsp25/Hsp25 ratio were determined by Western blot.

RESULTS

The administration of dexamethasone led to a significant elevation in 4-HNE levels in the myocardium of adult rats (p < 0.05; D vs. C). The concurrent implementation of exercise training impeded this increase (p > 0.05; DE vs. C). Exercise training induced a threefold increase in myocardial Hsp72 expression (p < 0.001; DE vs. C and D) and attenuated the dexamethasone-induced increase in Hsp25 phosphorylation (p < 0.05; C vs. D) (p < 0.001; DE vs. D).

CONCLUSION

Our results indicate that long-term administration of dexamethasone is associated with an increase in cardiac 4-HNE levels, which is hindered by the addition of exercise training.

Severe COVID-19 associated hyperglycemia is caused by beta cell dysfunction: a prospective cohort study

BACKGROUND

COVID-19, an infectious disease caused by SARS-CoV-2, was shown to be associated with an increased risk of new-onset diabetes. Mechanisms contributing to the development of hyperglycemia are still unclear. We aimed to study whether hyperglycemia is related to insulin resistance and/or beta cell dysfunction.

MATERIALS AND METHODS

Survivors of severe COVID-19 but without a known history of diabetes were examined at baseline (T0) and after 3 (T3) and 6 (T6) months: corticosteroids use, indirect calorimetry, and OGTT. Insulin response and sensitivity (IS) were expressed as insulinogenic (IGI), disposition (DI), and Matsuda insulin sensitivity index (ISI). Resting energy expenditure (REE) and respiratory quotient (RQ) was calculated from the gas exchange and nitrogen losses.

RESULTS

26 patients (out of 37) with complete outcome data were included in the analysis (age ~59.0 years; BMI ~ 30.4, 35% women). Patients were hypermetabolic at T0 (30.3 ± 4.0 kcal/kg lean mass/day, ~120% predicted) but REE declined over 6 months (ΔT6-T0 mean dif. T6-T0 (95% CI): -5.4 (-6.8, -4.1) kcal/kg FFM/day, p < 0.0001). 17 patients at T0 and 13 patients at T6 had hyperglycemia. None of the patients had positive islet autoantibodies. Insulin sensitivity in T0 was similarly low in hyperglycemic (H) and normoglycemic patients (N) (T0 ISI_H = 3.12 ± 1.23, ISI_N = 3.47 ± 1.78, p = 0.44), whereas insulin response was lower in the H group (DI_H = 3.05 ± 1.79 vs DI_N = 8.40 ± 5.42, p = 0.003). Over 6 months ISI (ΔT6-T0 mean dif. T6-T0 for ISI (95% CI): 1.84 (0.45, 3.24), p = 0.01)) increased in the H group only.

CONCLUSIONS

Patients with severe COVID-19 had increased REE and insulin resistance during the acute phase due to the infection and corticosteroid use, but these effects do not persist during the follow-up period. Only patients with insufficient insulin response developed hyperglycemia, indicating that beta cell dysfunction, rather than insulin resistance, was responsible for its occurrence.

Changes in glucose metabolism among recipients with diabetes 1 year after kidney transplant: a multicenter 1-year prospective study

Background

Diabetes mellitus is a common and crucial metabolic complication in kidney transplantation. It is necessary to analyze the course of glucose metabolism in patients who already have diabetes after receiving a transplant. In this study, we investigated the changes in glucose metabolism after transplantation, and a detailed analysis was performed on some patients whose glycemic status improved.

Methods

The multicenter prospective cohort study was conducted between 1 April 2016 and 31 September 2018. Adult patients (aged 20 to 65 years) who received kidney allografts from living or deceased donors were included. Seventy-four subjects with pre-transplant diabetes were followed up for 1 year after kidney transplantation. Diabetes remission was defined as the results of the oral glucose tolerance test performed one year after transplantation and the presence or absence of diabetes medications. After 1-year post-transplant, 74 recipients were divided into the persistent diabetes group (n = 58) and the remission group (n = 16). Multivariable logistic regression was performed to identify clinical factors associated with diabetes remission.

Results

Of 74 recipients, 16 (21.6%) showed diabetes remission after 1-year post-transplant. The homeostatic model assessment for insulin resistance numerically increased in both groups throughout the first year after transplantation and significantly increased in the persistent diabetes group. The insulinogenic index (IGI₃₀) value significantly increased only in the remission group, and the IGI₃₀ value remained low in the persistent diabetes group. In univariate analysis, younger age, newly diagnosed diabetes before transplantation, low baseline hemoglobin A1c, and high baseline IGI₃₀ were significantly associated with remission of diabetes. After multivariate analysis, only newly diagnosed diabetes before transplantation and IGI₃₀ at baseline were associated with remission of diabetes (34.00 [1.192-969.84], P = 0.039, and 17.625 [1.412-220.001], P = 0.026, respectively).

Conclusion

In conclusion, some kidney recipients with pre-transplant diabetes have diabetes remission 1 year after transplantation. Our prospective study revealed that preserved insulin secretory function and newly diagnosed diabetes at the time of kidney transplantation were favorable factors for which glucose metabolism did not worsen or improve 1 year after kidney transplantation.

Association between glucocorticoid use and all-cause mortality in critically ill patients with heart failure: A cohort study based on the MIMIC-III database

Background: Heart failure (HF) is the terminal stage of various heart diseases. Conventional treatments have poor efficacy, and diuretic resistance can present. Previous studies have found that the use of glucocorticoids can enhance the diuretic effect of patients with heart failure and reduce heart failure symptoms. However, the relationship between glucocorticoid use and mortality in patients with heart failure in intensive care units is unclear. Objectives: The aim of this study was to determine the association between glucocorticoid use and all-cause mortality in critically ill patients with heart failure. Methods: The information on patients with heart failure in this study was extracted from the MIMIC-III (Medical Information Mart for Intensive Care-III) database. Patients in the glucocorticoid and non-glucocorticoid groups were matched using propensity scores. The Kaplan-Meier method was used to explore the difference in survival probability between the two groups. A Cox proportional-hazards regression model was used to analyze the hazard ratios (HRs) for the two patient groups. Subgroup analyses were performed with prespecified stratification variables to demonstrate the robustness of the results. Results: The study included 9,482 patients: 2,099 in the glucocorticoid group and 7,383 in the non-glucocorticoid group. There were 2,055 patients in each group after propensity-score matching. The results indicated that the non-glucocorticoid group was not significantly associated with reduced mortality in patients with heart failure during the 14-day follow-up period [HRs = .901, 95% confidence interval (CI) = .767-1.059]. During the follow-up periods of 15-30 and 15-90 days, the mortality risk was significantly lower in the non-glucocorticoid group than in the glucocorticoid group (HRs = .497 and 95% CI = .370-.668, and HRs = .400 and 95% CI = .310-.517, respectively). Subgroup analyses indicated no interaction among each stratification variable and glucocorticoid use. Conclusion: Glucocorticoid use was associated with an increased mortality risk in critically ill patients with heart failure.

Carvedilol ameliorates dexamethasone-induced myocardial injury in rats independent of its action on the α1-adrenergic receptor

The current study aimed to investigate the cardiotoxic effect of dexamethasone-high-dose in rats, the therapeutic effect of carvedilol and the role of α1-adrenergic receptor (α1AR). The experiment involved 6 groups: control, dexamethasone (10 mg/kg), carvedilol (10 mg/kg), phenylephrine (1 mg/kg), phenylephrine plus carvedilol and propranolol (30 mg/kg). Drugs and vehicles were given for 7 days. Dexamethasone was given with the drugs in the last 4 groups. On the 8th-day and after overnight fasting, serum and cardiac samples were collected. Serum levels of cardiac troponin I and creatine kinase-myoglobin as well as cardiac levels of diacylglycerol, malondialdehyde, kinase activity of Akt, transforming growth factor-β, Smad3 and alpha smooth muscle actin were measured. Cardiac samples were also used for histopathological examination using hematoxylin-eosin and Sirius red stains, in addition to immunohistochemical examination using β-arrestin2 antibody. Dexamethasone induced cardiac injury via increasing oxidative stress, apoptosis and profibrotic signals. Carvedilol significantly reduced the dexamethasone-induced cardiotoxicity. Using phenylephrine, a competitive α1-agonist, with carvedilol potentiated the cardioprotective actions of carvedilol. Propranolol, a β-blocker without activity on α1ARs, showed higher cardiac protection than carvedilol. Dexamethasone-high-dose upregulates cardiac oxidative stress, apoptotic and profibrotic signals and induces cardiac injury. Blocking the α1-adrenergic receptor by carvedilol attenuates its cardioprotective effects against dexamethasone-induced cardiotoxicity.

Sex differences in saliva-based DNA methylation changes and environmental stressor in young African American adults

BACKGROUND

Low socioeconomic status neighborhood exposure to stress and violence may be sources of negative stimuli that poses significant health risks for children, adolescents and throughout the life course of an individual. The study aims to investigate if aberrant epigenetic DNA methylation changes may be a potential mechanism for regulating neighborhood exposures and health outcomes.

METHODS

Exposure to environmental stressors identified in 98 young African American (AA) adults aged 18-25 years old from the Washington D.C., area were used in the study. We correlated the association between stress markers; cortisol, CRP, IgG, IGA, IgM, and self-reported exposure to violence and stress, with quantitative DNA methylation changes in a panel of gene-specific loci using saliva DNA.

RESULTS

In all participants studied, the exposure to violence was significant and negatively correlated with DNA methylation of MST1R loci (p = 0.032; r = -0.971) and nominally significant with NR3C1 loci (p = 0.053; r = -0.948). In addition, we observed significant and negative correlation of DNA methylation changes of LINE1 (p = 0.044; r = -0.248); NR3C1 (p = 0.017; r = -0.186); MSTR1 (p = 0.022; r = -0.192); and DRD2 (p = 0.056; r = -0.184; albeit nominal significant correlation) with IgA expression. On the other hand, we observed a significant and position correlation of DNA methylation changes in DRD2 (p = 0.037; r = 0.184) with IgG expression. When participants were stratified by sex, we observed in AA young male adults, significant DNA methylation changes of MST1R (p< 0.05) and association with exposure to violence and IgG level. We also observed significant DNA methylation levels of DRD2 (p< 0.05) and association with IgA, IgG, and cortisol level. Furthermore, we observed significant DNA methylation changes of NR3C1 (p< 0.05) with stress, IgA, and IgG in the male participants only. On the other hand, we only observed significant and a positive association of IgG with DNA methylation levels of ESR1 (p = 0.041) in the young AA female participants.

CONCLUSION

Our preliminary observation of significant DNA methylation changes in neuronal and immune genes in saliva samples supports our recently published genome-wide DNA methylations changes in blood samples from young AA male adults indicating that saliva offers a non-invasive means for DNA methylation prediction of exposure to environmental stressors in a gender-specific manner.

New Insights into the Role of Insulin and Hypothalamic-Pituitary-Adrenal (HPA) Axis in the Metabolic Syndrome

Recent data suggests that (pre)diabetes onset is preceded by a period of hyperinsulinemia. Consumption of the "modern" Western diet, over-nutrition, genetic background, decreased hepatic insulin clearance, and fetal/metabolic programming may increase insulin secretion, thereby causing chronic hyperinsulinemia. Hyperinsulinemia is an important etiological factor in the development of metabolic syndrome, type 2 diabetes, cardiovascular disease, polycystic ovarian syndrome, and Alzheimer's disease. Recent data suggests that the onset of prediabetes and diabetes are preceded by a variable period of hyperinsulinemia. Emerging data suggest that chromic hyperinsulinemia is also a driving force for increased activation of the hypothalamic-adrenal-pituitary (HPA) axis in subjects with the metabolic syndrome, leading to a state of "functional hypercortisolism". This "functional hypercortisolism" by antagonizing insulin actions may prevent hypoglycemia. It also disturbs energy balance by shifting energy fluxes away from muscles toward abdominal fat stores. Synergistic effects of hyperinsulinemia and "functional hypercortisolism" promote abdominal visceral obesity and insulin resistance which are core pathophysiological components of the metabolic syndrome. It is hypothesized that hyperinsulinemia-induced increased activation of the HPA axis plays an important etiological role in the development of the metabolic syndrome and its consequences. Numerous studies have demonstrated reversibility of hyperinsulinemia with lifestyle, surgical, and pharmaceutical-based therapies. Longitudinal studies should be performed to investigate whether strategies that reduce hyperinsulinemia at an early stage are successfully in preventing increased activation of the HPA axis and the metabolic syndrome.

The Association of Acute Phase Proteins in Stress and Inflammation-Induced T2D

Acute phase proteins (APPs), such as plasminogen activator inhibitor-1 (PAI-1), serum amyloid A (SAA), and C-reactive protein (CRP), are elevated in type-2 diabetes (T2D) and are routinely used as biomarkers for this disease. These APPs are regulated by the peripheral mediators of stress (i.e., endogenous glucocorticoids (GCs)) and inflammation (i.e., pro-inflammatory cytokines), with both implicated in the development of insulin resistance, the main risk factor for the development of T2D. In this review we propose that APPs, PAI-1, SAA, and CRP, could be the causative rather than only a correlative link between the physiological elements of risk (stress and inflammation) and the development of insulin resistance.

Steroid-mediated liver steatosis is CD1d-dependent, while steroid-induced liver necrosis, inflammation, and metabolic changes are CD1d-independent

Introduction

Glucocorticoids contribute to the pathogenesis of non-alcoholic fatty liver disease (NAFLD). Natural killer T cells play a role in the pathogenesis of NAFLD and response to steroids. The present study aimed to determine the role of CD1d in steroid-mediated metabolic derangement and the steroid-protective effect of glycosphingolipids.

Methods

Ten groups of mice were studied. Steroids were orally administered to C57BL/6 mice to assess the therapeutic effect of β-glucosylceramide (GC) on the development of steroid-mediated liver damage and metabolic derangements. The role of CD1d in the pathogenesis of steroid-induced liver damage and in mediating the hepatoprotective effect of GC was studied in CD1d^−/− mice.

Results

A model of oral administration of steroids was established, resulting in insulin resistance, hyperinsulinemia, hypertriglyceridemia, liver steatosis, and hepatocellular injury. Steroid administration to CD1d^−/− mice was associated with hyperglycemia and hypertriglyceridemia. However, CD1d^−/− mice did not manifest marked steroid-induced steatosis. GC treatment alleviated steroid-associated metabolic derangements and liver injury independent of CD1d expression.

Conclusion

A steroid-mediated model of NAFLD and metabolic derangements was established in which steroid-mediated steatosis was CD1d-dependent while steroid-induced liver necrosis, inflammation, and metabolic changes were CD1d-independent, which may support a dichotomy between steatosis and steatohepatitis in NAFLD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12876-022-02242-9.

Safety and metabolic advantages of steroid withdrawal after 6 months posttransplant in de novo kidney transplantation: A 1‐year prospective cohort study

Introduction

This prospective multicenter study aimed at investigating the safety and metabolic advantages of steroid withdrawal (SW) therapy in kidney transplant recipients with tacrolimus–mycophenolate mofetil‐based immunosuppression.

Methods

We analyzed 179 recipients who received kidney transplantation from March 2016 and September 2018. In 179 recipients, 114 patients maintained an immunosuppressive regimen including steroids (steroid continuation [SC] group). The remaining 65 patients were determined to withdraw steroid therapy after 6 months posttransplant (SW group). Metabolic parameters and graft functions of the two groups were evaluated.

Results

The estimated glomerular filtration rates at 12 months posttransplant were 67.29 ± 20.29 ml/min/1.73 m² in SC group and 73.72 ± 17.57 ml/min/1.73 m² in SW group (p < .001). The acute rejection occurred to four recipients in the SC group (3.5%) and no acute rejection occurred to SW group recipients during the 6–2 months posttransplant period. Oral glucose tolerance tests revealed that recipients in the SW group were more improved in glucose metabolism than the SC group during 6–12 months posttransplant. In addition, cholesterol levels and blood pressure decreased after the withdrawal of steroids in the SW group.

Conclusion

In conclusion, a 6‐month withdrawal of steroids in recipients with low immunological risk and stable graft function can be safely conducted and result in improvement of metabolic profiles. Stable recipients without biopsy‐proven acute rejection and proteinuria can safely withdraw from steroids out of a maintenance immunosuppressive regimen 6‐months posttransplant. A long‐term follow‐up study is needed to verify our results.

New DXA Diagnostic Indexes of Abdominal Obesity

Aim: Cushing's syndrome (CS) is associated with weight gain and extreme central, visceral, abdominal obesity which is confirmed with dual-energy X-rays absorptiometric (DXA) diagnostic cut-off point (CP) values of central obesity indexes (COI), determined as an android to gynoid tissue and fat mass ratios. These best differentiate CS from non-CS obese women matched with CS according to their age and BMI. The aim of this study was to determine the CP values of new DXA indexes of central, abdominal obesity as a ratio of android and trunk to legs as well as trunk and legs to total tissue and fat mass that best differentiate CS and matched non-CS obese women in order to confirm central abdominal obesity, and to determine their normal CP values that best differentiate healthy non-obese women from CS and non-CS obese women, and to exclude abdominal obesity completely. Material and Methods: DXA indexes of abdominal obesity, calculated as а ratio of regional body fat and tissue mass compartments android to legs (A/L), trunk to legs (Tr/L), trunk to total (Tr/To) and legs to total (L/To) values were determined among 4 groups. Each group consisted of 18 women: 1^st group of CS, 2^nd group of obese women (O₁) not different according to their age and BMI from CS, 3^rd group of obese women (O₂) with higher BMI of 35 ± 1.2 kg and a 4^th group of non-obese, healthy women (C) with a normal BMI. Diagnostic accuracy (DG) of CP values of DXA indexes of abdominal obesity and indexes of normal body fat distribution (BFD) were determined. Results: A/L, Tr/L, Tr/To, and L/To DXA indexes were significantly different between CS and O₁ as well as between non-CS women O₂ compared to O₁ and C. These indexes had a highly significant correlation among each other and also in relation to their BMI (p < 0.0001). A/L-Tm CP value of 0.3 best differentiated the CS from group O₁, with the highest DG of 100 % and an A/L-Fm CP value of 0.26 differentiated them with a DG of 94.44% and sensitivity of 100 %. An A/L-Tn CP value of 0.23 and an A/L-Fn CP value of 0.25 best differentiated CS and C as well as O₂ and C for the highest DG of 100 %. Conclusions: DXA indexes A/L, Tr/L, Tr/To and L/To values were significantly different among the four groups. These values correlated significantly among them and with their BMI in non-CS groups, thus confirming a BMI increase association with a more pronounced abdominal BFD. An A/L-Tm CP value of 0.3 and an A/L-Fm CP value of 0.26 were discovered as the best DXA diagnostic indexes of extreme abdominal obesity in CS and these could also be used in discovering abdominal BFD in non-CS obese women with metabolic syndrome (MS). An A/L-Tn CP value of 0.23 and an A/L-Fn CP value of 0.25 were discovered as the best DXA diagnostic indexes of normal BFD which completely excluded abdominal obesity.

Dexamethasone is associated with early deaths in light chain amyloidosis patients with severe cardiac involvement

Background

Cardiac light chain amyloidosis (AL-CA) patients often die within three months of starting chemotherapy. Chemotherapy for non-immunoglobulin M gammopathy with AL-CA frequently includes bortezomib (Bor), cyclophosphamide (Cy), and dexamethasone (D). We previously reported that NT-ProBNP levels can double within 24h of dexamethasone administration, suggesting a deleterious impact on cardiac function. In this study, we evaluate the role of dexamethasone in early cardiovascular mortality during treatment.

Methods and findings

We retrospectively assessed 100 de novo cardiac AL patients (62% male, mean age 68 years) treated at our institute between 2009 and 2018 following three chemotherapy regimens: CyBorDComb (all initiated on day 1; 34 patients), DCyBorSeq (D, day 1; Cy, day 8; Bor, day 15; 17 patients), and CyBorDSeq (Cy, day 1; Bor, day 8; D, day 15; 49 patients). The primary endpoint was cardiovascular mortality and cardiac transplantation at days 22 and 455. At day 22, mortality was 20.6% with CyBorDComb, 23.5% with DCyBorSeq, and 0% with CyBorDSeq (p = 0.003). At day 455, mortality was not significantly different between regimens (p = 0.195). Acute toxicity of dexamethasone was evaluated on myocardial function using a rat model of isolated perfused heart. Administration of dexamethasone induced a decrease in left ventricular myocardium contractility and relaxation (p<0.05), supporting a potential negative inotropic effect of dexamethasone in AL-CA patients with severe cardiac involvement.

Conclusion

Delaying dexamethasone during the first chemotherapy cycle reduces the number of early deaths without extending survival. It is clear that dexamethasone is beneficial in the long-term treatment of patients with AL-CA. However, the initial introduction of dexamethasone during treatment is critical, but may be associated with early cardiac deaths in severe CA. Thus, it is important to consider the dosage and timing of dexamethasone introduction on a patient-severity basis. The impact of dexamethasone in the treatment of AL-CA needs further investigation.

Possible role of corticosterone in proteolysis, glycolytic, and amino acid metabolism in primary cultured avian myotubes incubated at high-temperature conditions

Excess glucocorticoid secretion induces oxidative damage and muscle proteolysis and modulates glucose and lipid metabolism. It is known that the high-temperature (HT) treatment enhances corticosterone (CORT) secretion, muscle proteolysis, and mitochondrial reactive oxygen species (mtROS) generation in chickens. The present study investigated the co-effects of CORT on proteolysis and mtROS production, together with glucose, fatty acid, and amino acid metabolism in HT-treated cells. Myoblast cells were isolated from the major pectoralis muscle of five 0- or 1-day-old neonatal chicks and were precultured at 37°C/CO₂ conditions for 48 h to reach subconfluent (80%-90%) conditions. Cells were then reseeded onto a 6- or 24-well microplate for the subsequent measurement, followed by the culture under a control temperature (37°C, control) or HT (41°C) conditions for 1 or 6 h. The HT-treated cells were cocultured with physiologically relevant concentrations of CORT (20 ng/mL in dimethyl sulfoxide). The HT treatment decreased cellular protein content (P < 0.05) and increased atrogin-1 mRNA levels and mtROS generation levels compared to the control group (P < 0.05), whereas HT/CORT co-treatment did not induce changes in either parameter. The mRNA level of glucose transporter-1 was decreased in HT-treated cells compared to that in normal cells (P < 0.05), and the decrease was increased in the CORT co-treatment (P < 0.05). While HT treatment did not alter pyruvate dehydrogenase kinase-4 mRNA level, the level was increased in the CORT co-treatment compared to the control and HT-treated cells (P < 0.05). Neither HT nor HT/CORT treatments altered the mRNA levels of fatty acid oxidation-related factors, carnitine palmitoyl transferase-1, and cluster of differentiation 36. The study conducted a metabolic analysis using gas chromatography-mass spectrometry. The results showed that HT/CORT-treated cells had decreased intracellular citrate and α-ketoglutarate levels (P < 0.05) and increased extracellular alanine and amino acid that have gluconeogenic properties, as well as increased aspartate, isoleucine, serine, methionine, and threonine levels (P < 0.05) compared to HT-treated cells. These results suggest that CORT may not affect proteolysis and mtROS production but can suppress pyruvate oxidation and promote alanine production in HT-treated chickens.

Lasting Effects of Low to Non-Lethal Radiation Exposure during Late Gestation on Offspring's Cardiac Metabolism and Oxidative Stress

Ionizing radiation (IR) is known to cause fetal programming, but the physiological effects of low-dose IR are not fully understood. This study examined the effect of low (50 mGy) to non-lethal (300 and 1000 mGy) radiation exposure during late gestation on cardiac metabolism and oxidative stress in adult offspring. Pregnant C57BL/6J mice were exposed to 50, 300, or 1000 mGy of gamma radiation or Sham irradiation on gestational day 15. Sixteen weeks after birth, ¹⁸F-Fluorodeoxyglucose (FDG) uptake was examined in the offspring using Positron Emission Tomography imaging. Western blot was used to determine changes in oxidative stress, antioxidants, and insulin signaling related proteins. Male and female offspring from irradiated dams had lower body weights when compared to the Sham. 1000 mGy female offspring demonstrated a significant increase in ¹⁸F-FDG uptake, glycogen content, and oxidative stress. 300 and 1000 mGy female mice exhibited increased superoxide dismutase activity, decreased glutathione peroxidase activity, and decreased reduced/oxidized glutathione ratio. We conclude that non-lethal radiation during late gestation can alter glucose uptake and increase oxidative stress in female offspring. These data provide evidence that low doses of IR during the third trimester are not harmful but higher, non-lethal doses can alter cardiac metabolism later in life and sex may have a role in fetal programming.

Glucocorticoid Receptor Alpha Targets SLC2A4 to Regulate Protein Synthesis and Breakdown in Porcine Skeletal Muscle Cells

In the presence of stress, the hypothalamic-pituitary-adrenal (HPA) axis activity can be enhanced to promote the secretion of a large amount of glucocorticoids (GCs), which play an important role in the anabolism and catabolism of skeletal muscle. When the endogenous and exogenous glucocorticoids are deficient or excessive, the body will produce stress-related resistance and change the protein metabolism. In this study, we investigated the effect of GC receptor GRα on protein breakdown and synthesis in porcine skeletal muscle cells (PSCs). Overexpression of GRα was shown to increase the expression of protein degradation-related genes, while knockdown of GRα decreased the expression of these genes. Additionally, we found a relationship between GRα and solute carrier family 2 member 4 (SLC2A4), SLC2A4 expression level increases when stress occurs, suggesting that increasing SLC2A4 expression can partially alleviate stress-induced damage, and we found that there is a combination between them via luciferase reporter assays, which still needs to be confirmed in further studies.

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.

Insulin Secretion and Insulin Resistance Trajectories over 1 Year after Kidney Transplantation: A Multicenter Prospective Cohort Study

BACKGROUND

We investigated the changing patterns of insulin secretion and resistance and risk factors contributing to the development of post-transplant diabetes mellitus (PTDM) in kidney recipients under tacrolimus-based immunosuppression regimen during 1 year after transplantation.

METHODS

This was a multicenter prospective cohort study. Of the 168 subjects enrolled in this study, we analyzed a total 87 kidney transplant recipients without diabetes which was assessed by oral glucose tolerance test before transplantation. We evaluated the incidence of PTDM and followed up the index of insulin secretion (insulinogenic index [IGI]) and resistance (homeostatic model assessment for insulin resistance [HOMA-IR]) at 3, 6, 9 months, and 1 year after transplantation by oral glucose tolerance test and diabetes treatment. We also assessed the risk factors for incident PTDM.

RESULTS

PTDM developed in 23 of 87 subjects (26.4%) during 1 year after transplantation. More than half of total PTDM (56.5%) occurred in the first 3 months after transplantation. During 1 year after transplantation, insulin resistance (HOMA-IR) was increased in both PTDM and no PTDM group. In no PTDM group, the increase in insulin secretory function to overcome insulin resistance was also observed. However, PTDM group showed no increase in insulin secretion function (IGI). Old age, status of prediabetes and episode of acute rejection were significantly associated with the development of PTDM.

CONCLUSION

In tacrolimus-based immunosuppressive drugs regimen, impaired insulin secretory function for reduced insulin sensitivity contributed to the development of PTDM than insulin resistance during 1 year after transplantation.

Serum metabolomics approach to monitor the changes in metabolite profiles following renal transplantation

Systemic metabolic changes after renal transplantation reflect the key processes that are related to graft accommodation. In order to describe and better understand these changes, the ¹HNMR based metabolomics approach was used. The changes of 47 metabolites in the serum samples of 19 individuals were interpreted over time with respect to their levels prior to transplantation. Considering the specific repeated measures design of the experiments, data analysis was mainly focused on the multiple analyses of variance (ANOVA) methods such as ANOVA simultaneous component analysis and ANOVA-target projection. We also propose here the combined use of ANOVA and classification and regression trees (ANOVA-CART) under the assumption that a small set of metabolites the binary splits on which may better describe the graft accommodation processes over time. This assumption is very important for developing a medical protocol for evaluating a patient's health state. The results showed that besides creatinine, which is routinely used to monitor renal activity, the changes in levels of hippurate, mannitol and alanine may be associated with the changes in renal function during the post-transplantation recovery period. Specifically, the level of hippurate (or histidine) is more sensitive to any short-term changes in renal activity than creatinine.

Cardiovascular and metabolic risk factors in patients with subclinical Cushing

PURPOSE

Adrenal incidentalomas (AI) are discovered after work-up unrelated to adrenal gland diseases; up to 30% of AI show subclinical endogenous cortisol excess (SH), frequently associated to hypertension, obesity, metabolic disorders and increased incidence of cardiovascular events (CVEs).

METHODS

We analysed 628 AI patients divided into two groups: 471 non-functional adrenal adenoma (NFA) and 157 SH. All patients underwent complete examinations, 24-h ambulatory blood pressure monitoring, biohumoral parameters and vascular damage markers, such as c-IMT and ankle brachial index. After long-term follow-up, we registered newly onset of CVEs such as myocardial infarction (MI), percutaneous stenting and surgical bypass (PTA/CABG), stroke, overall/cardiovascular mortality. Moreover, SH patients underwent to surgical (SSH) or pharmacological treatment (MSH).

RESULTS

SH patients showed higher prevalence of metabolic syndrome, diabetes mellitus, and previous CVEs respect NFA at baseline. After follow-up MSH group showed higher recurrence of major CV events compared with NFA and SSH (RR 2.27 MSH vs NFA for MI; RR 2.30 MSH vs NFA for PTA/CABG; RR 2.41 MSH vs NFA for stroke). In SSH there was a significant reduction of the number of antihypertensive medications needed to reach target blood pressure levels (2.3 ± 1.0 to 1.5 ± 0.4 drugs). None differences were found in SH patients, distinguished in relation to cortisol plasma levels after dexamethasone suppression test (1.8-5 µg/dL, above 5 µg/dL).

CONCLUSIONS

SH is linked to relevant cardiovascular and metabolic alterations, leading to worsen clinical outcomes. In eligible patients, adrenalectomy is valid and safe option to treat SH, reducing cardiometabolic abnormalities.

Signalling Pathways Implicated in Alzheimer's Disease Neurodegeneration in Individuals with and without Down Syndrome

Down syndrome (DS), the most common cause of intellectual disability of genetic origin, is characterized by alterations in central nervous system morphology and function that appear from early prenatal stages. However, by the fourth decade of life, all individuals with DS develop neuropathology identical to that found in sporadic Alzheimer's disease (AD), including the development of amyloid plaques and neurofibrillary tangles due to hyperphosphorylation of tau protein, loss of neurons and synapses, reduced neurogenesis, enhanced oxidative stress, and mitochondrial dysfunction and neuroinflammation. It has been proposed that DS could be a useful model for studying the etiopathology of AD and to search for therapeutic targets. There is increasing evidence that the neuropathological events associated with AD are interrelated and that many of them not only are implicated in the onset of this pathology but are also a consequence of other alterations. Thus, a feedback mechanism exists between them. In this review, we summarize the signalling pathways implicated in each of the main neuropathological aspects of AD in individuals with and without DS as well as the interrelation of these pathways.

Environmental pyrethroid exposure and diabetes in U.S. adults

Pyrethroid insecticides have been used widely as replacements for organophosphate insecticides over the past decades. While several animal studies suggest that exposure to pyrethroids can alter glucose homeostasis, there is only limited evidence of the association between environmental pyrethroid exposure and diabetes risk in human populations. Therefore, we examined the National Health and Nutrition Examination Survey (NHANES) 2007-2010 data to determine the association between environmental pyrethroid exposure and the prevalence of diabetes in the general U.S. population. Using data on 2796 participants aged 20-79 years from NHANES 2007-2010, we estimated odds ratios (ORs) and 95% confidence intervals (CI) of the association between diabetes and urinary metabolite concentration of pyrethroids using logistic regression. The weighted prevalence of diabetes was 10.3%. The weighted geometric means and detection rate of 3-phenoxybenzoic acid (3-PBA), the most common nonspecific pyrethroid metabolite, were 0.41 μg/L (95% CI: 0.38, 0.45) and 72.0%, respectively. After adjusting for sociodemographic, behavioral, and metabolic factors, we found a significant dose-response relationship between urinary 3-PBA as quartile and prevalent diabetes (p-trend=0.007). Compared to the lowest quartile of 3-PBA, the highest quartile had OR of 2.18 (95% CI: 1.18, 4.03) for diabetes. Our finding suggests pyrethroid insecticides as a potential risk factor for diabetes. Further studies should be conducted to confirm our finding and to determine if this association is causal.

An overview of the emerging interface between cardiac metabolism, redox biology and the circadian clock

At various biological levels, mammals must integrate with 24-hr rhythms in their environment. Daily fluctuations in stimuli/stressors of cardiac metabolism and oxidation-reduction (redox) status have been reported over the course of the day. It is therefore not surprising that the heart exhibits dramatic oscillations in various cellular processes over the course of the day, including transcription, translation, ion homeostasis, metabolism, and redox signaling. This temporal partitioning of cardiac processes is governed by a complex interplay between intracellular (e.g., circadian clocks) and extracellular (e.g., neurohumoral factors) influences, thus ensuring appropriate responses to daily stimuli/stresses. The purpose of the current article is to review knowledge regarding control of metabolism and redox biology in the heart over the course of the day, and to highlight whether disruption of these daily rhythms contribute towards cardiac dysfunction observed in various disease states.

Erythrocyte glutathione transferase in kidney transplantation: a probe for kidney detoxification efficiency

Erythrocyte glutathione transferase (e-GST) is overexpressed in case of increased blood toxicity and its level correlates with the kidney disease progression. Thus, it represents a probe of kidney efficiency against circulating toxins. We measured the activity of e-GST in patients with transplant kidney from living and cadaver donors, correlated its level to biochemical parameters of kidney function, and measured the level of oxidized albumin as a probe of oxidative stress using a new simple procedure. Interestingly, the activity of e-GST in transplant patients from cadaver donors (N = 153) is very high (11.7 U/gHb) compared to healthy subjects (N = 80) ( 5.6 U/gHb). Lower values were observed in transplant patients with kidney from living donors (N = 16) (9.8 U/gHb). Except for steroids, no correlation has been found with the immunosuppressive therapies and routine clinical and laboratory parameters. Also serum oxidized albumin, which reveals oxidative stress, is significantly higher in transplant patients from cadaver donors (53%) compared to that from living donors (36%). Overall, these data indicate that most of transplant kidneys from cadavers lost part of the detoxifying power against circulating toxins and suffer a relevant oxidative stress compared to those coming from living donors. A case report suggests that e-GST could represent a very early marker of incipient graft rejection. In conclusion, e-GST may be used to check the decline or maintenance of the kidney detoxification competence during post-transplantation course.

Levels and Diagnostic Value of Model-based Insulin Sensitivity in Sepsis: A Preliminary Study

Background and Aims:

Currently, there is a lack of real-time metric with high sensitivity and specificity to diagnose sepsis. Insulin sensitivity (SI) may be determined in real-time using mathematical glucose-insulin models; however, its effectiveness as a diagnostic test of sepsis is unknown. Our aims were to determine the levels and diagnostic value of model-based SI for identification of sepsis in critically ill patients.

Materials and Methods:

In this retrospective, cohort study, we analyzed SI levels in septic (n = 18) and nonseptic (n = 20) patients at 1 (baseline), 4, 8, 12, 16, 20, and 24 h of their Intensive Care Unit admission. Patients with diabetes mellitus Type I or Type II were excluded from the study. The SI levels were derived by fitting the blood glucose levels, insulin infusion and glucose input rates into the Intensive Control of Insulin-Nutrition-Glucose model.

Results:

The median SI levels were significantly lower in the sepsis than in the nonsepsis at all follow-up time points. The areas under the receiver operating characteristic curve of the model-based SI at baseline for discriminating sepsis from nonsepsis was 0.814 (95% confidence interval, 0.675–0.953). The optimal cutoff point of the SI test was 1.573 × 10⁻⁴ L/mu/min. At this cutoff point, the sensitivity was 77.8%, specificity was 75%, positive predictive value was 73.7%, and negative predictive value was 78.9%.

Conclusions:

Model-based SI ruled in and ruled out sepsis with fairly high sensitivity and specificity in our critically ill nondiabetic patients. These findings can be used as a foundation for further, prospective investigation in this area.

Systemic Effects of Repeated Intraocular Dexamethasone Intravitreal Implant in Diabetic Patients: A Retrospective Study

INTRODUCTION

The objective of this study is to evaluate the influence of repeated intraocular dexamethasone implant (Ozurdex) injections on metabolic control in type 2 diabetic patients.

METHODS

Retrospective study of 165 type 2 diabetic patients starting Ozurdex treatment who received no less than three consecutive injections. Glycated hemoglobin (HbA1c), serum creatinine, total cholesterol, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, and triglycerides (TGs) were evaluated during 15 months of follow-up after Ozurdex treatment onset.

RESULTS

Fifty-seven patients met inclusion criteria. Mean baseline values for HbA1c, creatinine, total cholesterol, HDL cholesterol, and TGs before treatment (7.1%, 1.3, 176.7, 51.1, and 125.6 mg/dl, respectively) were similar to mean values after Ozurdex onset (Wilcoxon test p values were 0.68, 0.41, 0.06, 0.87, and 0.33, respectively) and remained stable during the follow-up period. Mean LDL cholesterol levels increased slightly after Ozurdex treatment onset (90.1 vs 88.2 mg/dl, p = 0.04) but after 15 months of follow-up they had returned to baseline values. Transient increase in LDL cholesterol was remarkable in the group of 24 bilaterally treated patients (96.8 vs 88.4 mg/dl, p = 0.03). A third of these patients increased their baseline LDL values by more than 20%. Even with continuous injections of Ozurdex, LDL cholesterol levels also declined back to baseline by month 15.

CONCLUSION

Ozurdex injections had no influence on HbA1c or renal function. Lipid profile changes were mild and transient. However, a significant temporary increase has been found in LDL cholesterol levels in patients receiving simultaneous bilateral injections. Lipid levels should be monitored in patients starting with bilateral Ozurdex injections especially in those with recent history of acute myocardial infarction.

Role of addiction and stress neurobiology on food intake and obesity

The US remains at the forefront of a global obesity epidemic with a significant negative impact on public health. While it is well known that a balance between energy intake and expenditure is homeostatically regulated to control weight, growing evidence points to multifactorial social, neurobehavioral and metabolic determinants of food intake that influence obesity risk. This review presents factors such as the ubiquitous presence of rewarding foods in the environment and increased salience of such foods that stimulate brain reward motivation and stress circuits to influence eating behaviors. These rewarding foods via conditioned and reinforcing effects stimulate not only metabolic, but also stress hormones, that, in turn, hijack the brain emotional (limbic) and motivational (striatal) pathways, to promote food craving and excessive food intake. Furthermore, the impact of high levels of stress and trauma and altered metabolic environment (e.g. higher weight, altered insulin sensitivity) on prefrontal cortical self-control processes that regulate emotional, motivational and visceral homeostatic mechanisms of food intake and obesity risk are also discussed. A heuristic framework is presented in which the interactive dynamic effects of neurobehavioral adaptations in metabolic, motivation and stress neurobiology may further support food craving, excessive food intake and weight gain in a complex feed-forward manner. Implications of such adaptations in brain addictive-motivational and stress pathways and their effects on excessive food intake and weight gain are discussed to highlight key questions that requires future research attention in order to better understand and address the growing obesity epidemic.

Impact of renal transplantation on glucose tolerance in Japanese recipients with impaired glucose tolerance

AIMS

To investigate changes in glucose tolerance, insulin secretion and insulin sensitivity in Japanese recipients before and 1 year after renal transplantation.

METHODS

We conducted a study of Japanese recipients without diabetes who underwent renal transplantation at Hokkaido University Hospital. A 75-g oral glucose tolerance test was performed before and 1 year after renal transplantation in these recipients. Insulin sensitivity was estimated using the Matsuda index and homeostasis model assessment of insulin resistance (HOMA-IR). Insulin secretion was evaluated based on the insulin secretion sensitivity index-2 (ISSI-2).

RESULTS

Of the 62 renal transplant recipients, 31 were diagnosed as having impaired glucose tolerance before transplantation. Among these 31 recipients, after 1 year, four had developed new-onset diabetes after transplantation, and nine had impaired glucose tolerance. Unexpectedly, 18 changed from impaired to normal glucose tolerance. When these recipients with impaired glucose tolerance were classified into a non-amelioration group and an amelioration group, the ISSI-2 was significantly reduced, with no significant changes in the Matsuda index or HOMA-IR, in the non-amelioration group 1 year after renal transplantation. By contrast, ISSI-2 and Matsuda index values were significantly increased, with no significant changes in HOMA-IR values in the amelioration group.

CONCLUSIONS

More than half of Japanese renal transplant recipients with impaired glucose tolerance had normal glucose tolerance 1 year after renal transplantation. These results suggest that an increase in insulin secretion and whole insulin sensitivity was associated with improvement in glucose tolerance in these recipients.

Steroid withdrawal after renal transplantation: a retrospective cohort study

BACKGROUND

Immunosuppressive regimens in renal transplantation frequently contain corticosteroids, but many centers withdraw steroids as a consequence of unwanted side effects of steroids. The optimal timing to withdraw steroids after transplantation, however, remains unclear. The aim of this study was to determine an optimal time point following kidney transplantation that is associated with reduced mortality without jeopardizing the allograft to allow safe discontinuation of steroids.

METHODS

We conducted a retrospective cohort study and computed a concatenated landmark-stratified Cox supermodel to estimate hazard ratios and 95% confidence intervals for mortality and graft loss using dynamic propensity score matching to adjust for confounding by indication.

RESULTS

A total of 6070 first kidney transplant recipients in the Austrian Dialysis and Transplant Registry who were transplanted between 1990 and 2012 were evaluated and classified according to steroid treatment status throughout follow-up after kidney transplantation; 2142 patients were withdrawn from steroids during the study period. Overall, 1131 patients lost their graft and 821 patients in the study cohort died. Steroid withdrawal within 18 months after transplantation was associated with an increased rate of graft loss compared to steroid maintenance during that time (6 months after transplantation: HR = 1.8; 95% CI, 1.3 to 2.6; 18 months after transplantation: HR = 1.3; 95% CI, 1.1 to 1.6; 24 months after transplantation: HR = 1.2; 95% CI, 0.9 to 1.5), while mortality was not different between groups.

CONCLUSIONS

Our findings suggest that steroid withdrawal after anti-IL-2 induction in the first 18 months after transplantation is associated with an increased risk of allograft loss.

Obesity and cancer, a case for insulin signaling

Obesity is a worldwide epidemic, with the number of overweight and obese individuals climbing from just over 500 million in 2008 to 1.9 billion in 2014. Type 2 diabetes (T2D), cardiovascular disease and non-alcoholic fatty liver disease have long been associated with the obese state, whereas cancer is quickly emerging as another pathological consequence of this disease. Globally, at least 2.8 million people die each year from being overweight or obese. It is estimated that by 2020 being overweight or obese will surpass the health burden of tobacco consumption. Increase in the body mass index (BMI) in overweight (BMI>25 kg/m²) and obese (BMI>30 kg/m²) individuals is a result of adipose tissue (AT) expansion, which can lead to fat comprising >50% of the body weight in the morbidly obese. Extensive research over the last several years has painted a very complex picture of AT biology. One clear link between AT expansion and etiology of diseases like T2D and cancer is the development of insulin resistance (IR) and hyperinsulinemia. This review focuses on defining the link between obesity, IR and cancer.

Metabolic analysis of canine peripheral blood mononuclear cells treated ex vivo with dexamethasone

In dogs, hyperadrenocorticism (HAC) is associated with insulin resistance and diabetes does progress with HAC. There are significant differences in the transcriptomic and proteomic patterns of activated T cells, which parallel the findings in muscle tissues. The aim of this study was to assess how glucocorticoids affect intracellular metabolites in canine peripheral blood mononuclear cells (CnPBMCs) using dexamethasone. A total of 96 metabolites were identified by capillary electrophoresis time-of-flight mass spectrometry (CE-TOFMS). After incubation with dexamethasone, the metabolites glucose 1-phosphate, glucose 6-phosphate, fructose 6-phosphate, sedoheptulose 7-phosphate and acetyl-CoA were significantly increased. However, ATP, CTP, dATP, pyruvic acid and NADP(+) were significantly decreased. These results show that a glucocorticoid reduces the catabolic reaction of glucose and accordingly decreases the glucose requirements of CnPBMCs.

Important role of 5-hydroxytryptamine in glucocorticoid-induced insulin resistance in liver and intra-abdominal adipose tissue of rats

Aim/Introduction

Both glucocorticoids and 5‐hydroxytryptamine (5‐HT) have been shown to induce insulin resistance (IR) in hepatocytes and adipocytes. Here, we explore whether there is a correlation between them.

Materials and Methods

Except for the control group, male rats were exposed to dexamethasone treated with or without para‐chlorophenylalanine (pCPA), or carbidopa for 20 days. Except for the control group, buffalo rat liver 3A (BRL‐3A) cells were exposed to dexamethasone for 24 h, treated with or without pCPA, carbidopa, or clorgiline for 48 h, or exposed to 5‐HT treated with or without fluoxetine for 48 h. Whole‐body IR was determined by both glucose tolerance test and measurement of fasting blood glucose and insulin, whereas hepatocytes or adipocytes IR was determined by examining either hepatic gluconeogenesis, steatosis and glucose transporter 2 expression or lipolysis.

Results

Dexamethasone‐induced whole‐body IR, liver and intraabdominal adipose IR were accompanied by upregulated expressions of tryptophan hydroxylase‐1 and aromatic amino acid decarboxylase with increased 5‐HT level in both tissues, which were attenuated significantly by pCPA, inhibiting tryptophan hydroxylase‐1, or carbidopa, inhibiting aromatic amino acid decarboxylase. [Correction added on 22 September 2015, after first online publication: ‘inhibiting aromatic amino acid decarboxylase’ was duplicated and has been replaced by ‘tryptophan hydroxylase‐1’.] In the BRL‐3A cells, dexamethasone‐induced IR was also accompanied by upregulated 5‐HT synthesis in dose‐ and time‐dependent manners, and was attenuated by pCPA or carbidopa, but exacerbated by clorgiline, inhibiting monoamine oxidase‐A to further increase 5‐HT level. Dexamethasone also enhanced 5‐HT 2A and 2B receptor expressions in both tissues and BRL‐3A cells. Additionally, blocking 5‐HT transporter with fluoxetine significantly suppressed 5‐HT‐induced IR in BRL‐3A cells.

Conclusion

Enhancement of 5‐HT synthesis in liver and intra‐abdominal adipose is an important reason for glucocorticoids‐induced IR.

Dose Dependent Hepatic and Endothelial Changes in Rats Treated with Dexamethasone

AIMS AND OBJECTIVES

To study the effect of dexamethasone on liver and endothelium, and to determine the optimum dose which induces the abnormal changes in liver and endothelium in Wistar rats.

MATERIALS AND METHODS

Albino Wistar rats were divided into 7 groups (n=6). Control group rats received normal saline. Graded doses of dexamethasone (0.5,1,2,4,8 and 16mg/kg/ i.p.) was administered to the groups for six days. Liver and aorta were dissected at the end of the study and examined for histopathological changes under microscope.

RESULTS

Intraperitoneal administration of dexamethasone (4,8 and 16mg/kg) for six days resulted in fatty changes in liver and same doses have shown thickening of endothelial layers in aorta, in comparison to control group. There were not much significant changes seen in low doses of dexamethasone (0.5, 1 and 2mg/kg).

CONCLUSION

It is concluded that the acute high doses of dexamethasone (4,8 and 16mg/kg) for six days caused hepatic steatosis and showed mild to moderate arteriosclerosis in aorta. These changes may be secondary consequences of insulin resistance. Hence, it can be used as new animal model to screen the various plants and medicines in the treatment of insulin resistance.

Glucocorticoids suppress GLP-1 secretion: possible contribution to their diabetogenic effects

Evidence indicates that subtle abnormalities in GC (glucocorticoid) plasma concentrations and/or in tissue sensitivity to GCs are important in the metabolic syndrome, and it is generally agreed that GCs induce insulin resistance. In addition, it was recently reported that short-term exposure to GCs reduced the insulinotropic effects of the incretin GLP-1 (glucagon-like peptide 1). However, although defective GLP-1 secretion has been correlated with insulin resistance, potential direct effects of GCs on GLP-1-producing L-cell function in terms of GLP-1 secretion and apoptosis have not been studied in any greater detail. In the present study, we sought to determine whether GCs could exert direct effects on GLP-1-producing L-cells in terms of GLP-1 secretion and cell viability. We demonstrate that the GR (glucocorticoid receptor) is expressed in GLP-1-producing cells, where GR activation in response to dexamethasone induces SGK1 (serum- and glucocorticoid-inducible kinase 1) expression, but did not influence preproglucagon expression or cell viability. In addition, dexamethasone treatment of enteroendocrine GLUTag cells reduced GLP-1 secretion induced by glucose, 2-deoxy-D-glucose, fructose and potassium, whereas the secretory response to a phorbol ester was unaltered. Furthermore, in vivo administration of dexamethasone to rats reduced the circulating levels of GLP-1 concurrent with induction of insulin resistance and glucose intolerance. We can conclude that GR activation in GLP-1-producing cells will diminish the secretory responsiveness of these cells to subsequent carbohydrate stimulation. These effects may not only elucidate the pathogenesis of steroid diabetes, but could ultimately contribute to the identification of novel molecular targets for controlling incretin secretion.

Antipsychotics-induced metabolic alterations: focus on adipose tissue and molecular mechanisms

The use of antipsychotic drugs for the treatment of mood disorders and psychosis has increased dramatically over the last decade. Despite its consumption being associated with beneficial neuropsychiatric effects in patients, atypical antipsychotics (which are the most frequently prescribed antipsychotics) use is accompanied by some secondary adverse metabolic effects such as weight gain, dyslipidemia and glucose intolerance. The molecular mechanisms underlying these adverse effects are not fully understood but have been suggested to involve a dysregulation of adipose tissue homeostasis. As such, the aim of this paper is to review and discuss the role of adipose tissue in the development of secondary adverse metabolic effects induced by atypical antipsychotics. Data analyzed in this article suggest that atypical antipsychotics may increase adipose tissue (particularly visceral adipose tissue) lipogenesis, differentiation/hyperplasia, pro-inflammatory mediator secretion and insulin resistance and decrease adipose tissue lipolysis. Consequently, patients receiving antipsychotic medication could be at risk of developing obesity, type 2 diabetes and cardiovascular disease. A better knowledge of the impact of these drugs on adipose tissue homeostasis may unveil strategies to develop novel antipsychotic drugs with less adverse metabolic effects and to develop adjuvant therapies (e.g. behavioral and nutritional therapies) to neuropsychiatric patients receiving antipsychotic medication.

The effect of early-life stress and chronic high-sucrose diet on metabolic outcomes in female rats

Early-life stress affects metabolic outcomes and choice of diet influences the development of metabolic disease. Here we tested the hypothesis that chronic sugar intake exacerbates metabolic deficits induced by early-life stress. Early-life stress was induced in Sprague-Dawley rats using limited nesting material in early lactation (LN, postnatal days 2-9), and siblings were given chow alone or with additional sucrose post weaning (n = 9-17 per group). Female control and LN siblings had unlimited access to either chow plus water, or chow and water plus 25% sucrose solution (Sucrose), from 3-15 weeks of age. Weekly body weight and food intake were measured. Glucose and insulin tolerance were tested at 13 and 14 weeks of age, respectively. Rats were killed at 15 weeks. Hepatic triglyceride and markers of lipid synthesis - fatty acid synthase, acetyl-CoA carboxylase alpha and oxidation - and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (Pgc-1α) were examined. Mediators of hepatic glucocorticoid metabolism, specifically 11-beta hydroxysteroid dehydrogenase-1 (11βHSD-1), 5-α reductase, and glucocorticoid and mineralocorticoid receptor mRNAs were also measured. Sucrose increased caloric intake in both groups, but overall energy intake was not altered by LN exposure. LN exposure had no further impact on sucrose-induced glucose intolerance and increased plasma and liver triglycerides. Hepatic markers of fat synthesis and oxidation were concomitantly activated and 11βHSD-1 mRNA expression was increased by 53% in LN-Sucrose versus Con-Sucrose rats. Adiposity was increased by 26% in LN-Sucrose versus Con-Sucrose rats. Thus, LN exposure had minimal adverse metabolic effects despite high-sugar diet postweaning.

Changes in morphology and function of adrenal cortex in mice fed a high-fat diet

BACKGROUND/OBJECTIVES

Obesity is a major risk factor for the development of type 2 diabetes and other debilitating diseases. Obesity and diabetes are intimately linked with altered levels of adrenal steroids. Elevated levels of these hormones induce insulin resistance and cause cardiovascular diseases. The mechanisms underlying obesity-related alterations in adrenal steroids are still not well understood. Here, we investigated how diet-induced obesity affects the morphology and function of the mouse adrenal cortex.

METHODS

We fed animals either a high-fat diet (HFD) or a normal diet (60% kcal from fat or 10% kcal from fat, respectively) for 18 weeks. We then assessed various aspects of adrenal gland morphology and function, as well as basal plasma concentrations of steroid hormones and ACTH.

RESULTS

We show that adrenal glands of mice fed a HFD release more corticosterone and aldosterone, resulting in higher plasma levels. This increase is driven by adrenal cortical hyperplasia, and by increased expression of multiple genes involved in steroidogenesis. We demonstrate that diet-induced obesity elevates Sonic hedgehog signaling in Gli1-positive progenitors, which populate the adrenal capsule and give rise to the steroidogenic cells of the adrenal cortex. Feeding animals with a HFD depletes Gli1-positive progenitors, as the adrenal cortex expands.

CONCLUSIONS

This work provides insight into how diet-induced obesity changes the biology of the adrenal gland. The association of these changes with increased Shh signaling suggests possible therapeutic strategies for obesity-related steroid hormone dysfunction.

Exercise intolerance in chronic heart failure: the role of cortisol and the catabolic state

Chronic heart failure (CHF) is a complex clinical syndrome leading to exercise intolerance due to muscular fatigue and dyspnea. Hemodynamics fail to explain the reduced exercise capacity, while a significant skeletal muscular pathology seems to constitute the main underlying mechanism for exercise intolerance in CHF patients. There have been proposed several metabolic, neurohormonal and immune system abnormalities leading to an anabolic/catabolic imbalance that plays a central role in the pathogenesis of the wasting process of skeletal muscle myopathy. The impairment of the anabolic axes is associated with the severity of symptoms and the poor outcome in CHF, whereas increased cortisol levels are predictive of exercise intolerance, ventilatory inefficiency and chronotropic incompetence, suggesting a significant contributing mechanism to the limited functional status. Exercise training and device therapy could have beneficial effects in preventing and treating muscle wasting in CHF. However, specific anabolic treatment needs more investigation to prove possible beneficial effects.

Meta-modeling of methylprednisolone effects on glucose regulation in rats

A retrospective meta-modeling analysis was performed to integrate previously reported data of glucocorticoid (GC) effects on glucose regulation following a single intramuscular dose (50 mg/kg), single intravenous doses (10, 50 mg/kg), and intravenous infusions (0.1, 0.2, 0.3 and 0.4 mg/kg/h) of methylprednisolone (MPL) in normal and adrenalectomized (ADX) male Wistar rats. A mechanistic pharmacodynamic (PD) model was developed based on the receptor/gene/protein-mediated GC effects on glucose regulation. Three major target organs (liver, white adipose tissue and skeletal muscle) together with some selected intermediate controlling factors were designated as important regulators involved in the pathogenesis of GC-induced glucose dysregulation. Assessed were dynamic changes of food intake and systemic factors (plasma glucose, insulin, free fatty acids (FFA) and leptin) and tissue-specific biomarkers (cAMP, phosphoenolpyruvate carboxykinase (PEPCK) mRNA and enzyme activity, leptin mRNA, interleukin 6 receptor type 1 (IL6R1) mRNA and Insulin receptor substrate-1 (IRS-1) mRNA) after acute and chronic dosing with MPL along with the GC receptor (GR) dynamics in each target organ. Upon binding to GR in liver, MPL dosing caused increased glucose production by stimulating hepatic cAMP and PEPCK activity. In adipose tissue, the rise in leptin mRNA and plasma leptin caused reduction of food intake, the exogenous source of glucose input. Down-regulation of IRS-1 mRNA expression in skeletal muscle inhibited the stimulatory effect of insulin on glucose utilization further contributing to hyperglycemia. The nuclear drug-receptor complex served as the driving force for stimulation or inhibition of downstream target gene expression within different tissues. Incorporating information such as receptor dynamics, as well as the gene and protein induction, allowed us to describe the receptor-mediated effects of MPL on glucose regulation in each important tissue. This advanced mechanistic model provides unique insights into the contributions of major tissues and quantitative hypotheses for the multi-factor control of a complex metabolic system.

Insulin resistance and environmental pollutants: experimental evidence and future perspectives

BACKGROUND

The metabolic disruptor hypothesis postulates that environmental pollutants may be risk factors for metabolic diseases. Because insulin resistance is involved in most metabolic diseases and current health care prevention programs predominantly target insulin resistance or risk factors thereof, a critical analysis of the role of pollutants in insulin resistance might be important for future management of metabolic diseases.

OBJECTIVES

We aimed to critically review the available information linking pollutant exposure to insulin resistance and to open the discussion on future perspectives for metabolic disruptor identification and prioritization strategies.

METHODS

We searched PubMed and Web of Science for experimental studies reporting on linkages between environmental pollutants and insulin resistance and identified a total of 23 studies as the prime literature.

DISCUSSION

Recent studies specifically designed to investigate the effect of pollutants on insulin sensitivity show a potential causation of insulin resistance. Based on these studies, a summary of viable test systems and end points can be composed, allowing insight into what is missing and what is needed to create a standardized insulin resistance toxicity testing strategy.

CONCLUSIONS

It is clear that current research predominantly relies on top-down identification of insulin resistance-inducing metabolic disruptors and that the development of dedicated in vitro or ex vivo screens to allow animal sparing and time- and cost-effective bottom-up screening is a major future research need.