Glucocorticoids Reprogram β-Cell Signaling to Preserve Insulin Secretion

Predictive factors that influence the clinical efficacy of umbilical cord-derived mesenchymal stromal cells in the treatment of type 2 diabetes mellitus

BACKGROUND

Our previous single-center, randomized, double-blinded, placebo-controlled phase 2 study evaluated the safety and effectiveness of human umbilical cord mesenchymal stromal cell (UC-MSC) transfusion for treating patients with type 2 diabetes mellitus (T2DM). Indeed, this potential treatment strategy was able to reduce insulin use by half in a considerable number of patients. However, many other patients' responses to UC-MSC transfusion were insignificant. The selection of patients who might benefit from UC-MSC treatment is crucial from a clinical standpoint.

METHODS

In this post hoc analysis, 37 patients who received UC-MSC transfusions were divided into two groups based on whether their glycated hemoglobin (hemoglobin A1c, or HbA1c) level was less than 7% after receiving UC-MSC treatment. The baseline differences between the two groups were summarized, and potential factors influencing efficacy of UC-MSCs for T2DM were analyzed by univariate and multivariate logistic regression. The correlations between the relevant hormone levels and the treatment effect were further analyzed.

RESULTS

At the 9-week follow-up, 59.5% of patients achieved their targeted HbA1c level. Male patients with lower baseline HbA1c and greater C-peptide area under the curve (AUCC-pep) values responded favorably to UC-MSC transfusion, according to multivariate analysis. The effectiveness of UC-MSCs transfusion was predicted by AUCC-pep (cutoff value: 14.22 ng/h/mL). Further investigation revealed that AUCC-pep was increased in male patients with greater baseline testosterone levels.

CONCLUSIONS

Male patients with T2DM with greater AUCC-pep may be more likely to respond clinically to UC-MSC therapy, and further large-scale multi-ethnic clinical studies should be performed to confirm the conclusion.

Prevalence of Steroid-Induced Hyperglycemia in King Abdulaziz Specialist Hospital, Taif City, Saudi Arabia

Background Hyperglycemia is a common side effect of high-dose steroid therapy in hospitalized patients. Objectives To assess the prevalence of hyperglycemia among hospitalized patients receiving steroid therapy. Methods A retrospective study was conducted among 245 patients. The inclusion criteria were patients undergoing steroid therapy and admitted to a single tertiary care hospital due to medical complications or exacerbation of the diseases they were suffering from. Data encompassing patient demographics, admission, discharge dates, comorbidities, medication histories, laboratory results (including blood glucose levels), and documented corticosteroid administrations were meticulously gathered from electronic health records (EHRs). A logistic regression model analysis was done to predict the risk factors of poor glycemic control among hospitalized patients. Results The prevalence of hyperglycemia among the patients who were on steroid therapy was 34.2%. About 70.7% of the patients who required insulin at the time of admission required >17 units, and the insulin requirement was significantly higher among patients who received dexamethasone compared to other steroids (p<0.05). Older age (>65 years) was found to be independently associated with poor glycemic control (p<0.05). Conclusion The study revealed that almost one-third of patients on steroid therapy had hyperglycemia. Monitoring of patients for hyperglycemia after beginning high-dose steroid therapy should be done.

Sensitivity of the Neuroendocrine Stress Axis in Metabolic Diseases

Metabolic diseases are prevalent in modern society and have reached pandemic proportions. Metabolic diseases have systemic effects on the body and can lead to changes in the neuroendocrine stress axis, the critical regulator of the body's stress response. These changes may be attributed to rising insulin levels and the release of adipokines and inflammatory cytokines by adipose tissue, which affect hormone production by the neuroendocrine stress axis. Chronic stress due to inflammation may exacerbate these effects. The increased sensitivity of the neuroendocrine stress axis may be responsible for the development of metabolic syndrome, providing a possible explanation for the high prevalence of severe comorbidities such as heart disease and stroke associated with metabolic disease. In this review, we address current knowledge of the neuroendocrine stress axis in response to metabolic disease and discuss its role in developing metabolic syndrome.

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

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

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.

Mouse Pancreatic Peptide Hormones Probed at the Sub-Single-Islet Level: The Effects of Acute Corticosterone Treatment

We combine liquid chromatography coupled with ion mobility spectrometry-mass spectrometry to elucidate how short exposure to corticosterone (Cort) alters the output of mouse pancreatic islet hormones. The workflow enables the robust separation of mouse insulin 1 (Ins1) and insulin 2 (Ins2) and the detection of major islet hormones in a homogenate equivalent to 100-150 islet cells. We show that Ins2 has a unique structure and is degraded much faster than Ins1. Further investigation indicates that Ins2 may populate both T and R states, whereas Ins1 may not. The assemblies of Ins1's B-chain also introduce more structural heterogeneity than Ins2. Collectively, these features account for their unique degradation profiles, the diabetes risk associated with Ins1, and the protective effect of Ins2. In the same experiments, we observe that the ratio of amylin to Ins1 increased significantly in Cort-treated mice (15:1) compared to the control mice (42:1), correlating well with β-cell proliferation observed in immunoassays on the same animal model. We observe no increase in intact full-length insulin levels but more of the truncated forms, indicating that enzymatic activity is accelerated. Our data provide a molecular basis for reduced insulin action induced by Cort and connections between insulin turnover and insulin resistance.

Perinatal stress exposure induced oxidative stress, metabolism disorder, and reduced GLUT-2 in adult offspring of rats

PURPOSE

Growing evidence has demonstrated that adversity in early life, especially in the prenatal and postnatal period, may change the programming of numerous body systems and cause the incidence of various disorders in later life. Accordingly, this experimental animal study aimed to investigate the effect of stress exposure during perinatal (prenatal and/or postnatal) on the induction of oxidative stress in the pancreas and its effect on glucose metabolism in adult rat offspring.

METHODS

In this experimental study based on maternal exposure to variable stress throughout the perinatal period, the pups were divided into eight groups, as follows: control group (C); prepregnancy, pregnancy, lactation stress group (PPPLS); prepregnancy stress group (PPS); pregnancy stress group (PS); lactation stress group (LS); prepregnancy, pregnancy stress group (PPPS); pregnancy, lactation stress group (PLS); and prepregnancy, lactation stress group (PPLS). Following an overnight fast on postnatal day (PND) 64, plasma glucose, insulin, leptin levels, and lipid profiles were evaluated in the offspring groups. GLUT-2 protein levels, lipid peroxidation, antioxidant status, and number of beta-cells in the pancreatic islets of Langerhans as well as the weights of intra-abdominal fat and adrenal glands were assessed. Levels of plasma corticosterone were determined in the different groups of mothers and offspring.

RESULTS

The levels of plasma corticosterone, insulin, and HOMA-B index increased, whereas glucose level and QUICKI index were reduced in the perinatal stress groups compared to C group (p < 0.001 to p < 0.05). Plasma triglyceride, LDL, and cholesterol level rose significantly, but HDL level decreased in the perinatal stress groups compared to C group (p < 0.001 to p < 0.05). Perinatal stress raised MDA concentrations and reduced the activities of antioxidant enzymes in plasma and pancreas compared to C group (p < 0.001 to p < 0.05). GLUT-2 protein levels and number of beta-cells in the stress groups declined compared to C group (p < 0.001 to p < 0.05). Intra-abdominal fat weight decreased in the PPS, PS, and LS groups compared to C group (p < 0.001 to p < 0.01), but adrenal gland weight remained unchanged.

CONCLUSION

Our results showed that long-term exposure to elevated levels of corticosterone during critical development induces metabolic syndrome in adult male rats.

Glucocorticoid-Induced Hyperinsulinism in a Preterm Neonate with Inherited ABCC8 Variant

Glucose homeostasis is a real challenge for extremely preterm infants (EPIs) who have both limited substrate availability and immature glucose metabolism regulation. In the first days of life, EPIs frequently develop transient glucose intolerance, which has a complex pathophysiology that associates unregulated gluconeogenesis, immature insulin secretion, and peripheral insulin resistance. In this population, glucocorticoid therapy is frequently administrated to prevent severe bronchopulmonary dysplasia. During this treatment, glucose intolerance classically increases and may lead to hyperglycemia. We report a case of neonatal hypoglycemia that was concomitant to a glucocorticoids administration, and that led to a congenital hyperinsulinism diagnosis in an EPI with a heterozygous ABCC8 variant. The variant was inherited from his mother, who had developed monogenic onset diabetes of the youth (MODY) at the age of 23. ABCC8 encodes a beta-cell potassium channel unit and causes congenital hyperinsulinism or MODY depending on the mutation location. Moreover, some mutations have been observed in the same patient to cause both hyperinsulinism in infancy and MODY in adulthood. In our case, the baby showed repeated and severe hypoglycemias, which were undoubtedly time-associated with the betamethasone intravenous administration. This hyperinsulinism was transient, and the infant has not yet developed diabetes at three years of age. We take the opportunity presented by this unusual clinical presentation to provide a review of the literature, suggesting new insights regarding the pathophysiology of the beta-pancreatic cells’ insulin secretion: glucocorticoids may potentiate basal insulin secretion in patients with ABCC8 mutation.

Flattening of circadian glucocorticoid oscillations drives acute hyperinsulinemia and adipocyte hypertrophy

Disruption of circadian glucocorticoid oscillations in Cushing's disease and chronic stress results in obesity and adipocyte hypertrophy, which is believed to be a main source of the harmful effects of obesity. Here, we recapitulate stress due to jet lag or work-life imbalances by flattening glucocorticoid oscillations in mice. Within 3 days, mice achieve a metabolic state with persistently high insulin, but surprisingly low glucose and fatty acids in the bloodstream, that precedes a more than 2-fold increase in brown and white adipose tissue mass within 3 weeks. Transcriptomic and Cd36-knockout mouse analyses show that hyperinsulinemia-mediated de novo fatty acid synthesis and Cd36-mediated fatty acid uptake drive fat mass increases. Intriguingly, this mechanism by which glucocorticoid flattening causes acute hyperinsulinemia and adipocyte hypertrophy is unexpectedly beneficial in preventing high levels of circulating fatty acids and glucose for weeks, thus serving as a protective response to preserve metabolic health during chronic stress.

Visualizing physiological parameters in cells and tissues using genetically encoded indicators for metabolites

The study of metabolism is undergoing a renaissance. Since the year 2002, over 50 genetically-encoded fluorescent indicators (GEFIs) have been introduced, capable of monitoring metabolites with high spatial/temporal resolution using fluorescence microscopy. Indicators are fusion proteins that change their fluorescence upon binding a specific metabolite. There are indicators for sugars, monocarboxylates, Krebs cycle intermediates, amino acids, cofactors, and energy nucleotides. They permit monitoring relative levels, concentrations, and fluxes in living systems. At a minimum they report relative levels and, in some cases, absolute concentrations may be obtained by performing ad hoc calibration protocols. Proper data collection, processing, and interpretation are critical to take full advantage of these new tools. This review offers a survey of the metabolic indicators that have been validated in mammalian systems. Minimally invasive, these indicators have been instrumental for the purposes of confirmation, rebuttal and discovery. We envision that this powerful technology will foster metabolic physiology.

Underlying mechanisms of glucocorticoid-induced β-cell death and dysfunction: a new role for glycogen synthase kinase 3

Glucocorticoids (GCs) are widely prescribed for their anti-inflammatory and immunosuppressive properties as a treatment for a variety of diseases. The use of GCs is associated with important side effects, including diabetogenic effects. However, the underlying mechanisms of GC-mediated diabetogenic effects in β-cells are not well understood. In this study we investigated the role of glycogen synthase kinase 3 (GSK3) in the mediation of β-cell death and dysfunction induced by GCs. Using genetic and pharmacological approaches we showed that GSK3 is involved in GC-induced β-cell death and impaired insulin secretion. Further, we unraveled the underlying mechanisms of GC-GSK3 crosstalk. We showed that GSK3 is marginally implicated in the nuclear localization of GC receptor (GR) upon ligand binding. Furthermore, we showed that GSK3 regulates the expression of GR at mRNA and protein levels. Finally, we dissected the proper contribution of each GSK3 isoform and showed that GSK3β isoform is sufficient to mediate the pro-apoptotic effects of GCs in β-cells. Collectively, in this work we identified GSK3 as a viable target to mitigate GC deleterious effects in pancreatic β-cells.

Meal Timing and Glycemic Control during Pregnancy-Is There a Link?

Hyperglycemia during pregnancy and gestational diabetes mellitus (GDM) constitute an important public health problem due to their prevalence and long-term health consequences both for the mother and offspring. Results from studies in rodents and some clinical investigations suggest that meal time manipulation may be a potential lifestyle approach against conditions involving perturbations in glucose homeostasis (e.g., hyperglycemia, insulin resistance, diabetes, etc.). The purpose of this review is to summarize and critically evaluate the current literature on the role of meal timing and daily nutrient distribution on glycemic control during pregnancy. Only a small number of mostly observational studies have assessed the role of meal timing in glucose homeostasis during pregnancy. Food consumption earlier in the day and short-term fasting with adequate nutrient intake may improve glycemic control during the second and third trimester of gestation. Considering that the field of chrononutrition is still in its infancy and many questions remain unanswered, future prospective and carefully designed studies are needed to better understand the role of meal timing in metabolic homeostasis and maternal and fetal health outcomes during pregnancy.

Non-glucose modulators of insulin secretion in healthy humans: (dis)similarities between islet and in vivo studies

Optimal metabolic homeostasis requires precise temporal and quantitative control of insulin secretion. Both in vivo and in vitro studies have often focused on the regulation by glucose although many additional factors including other nutrients, neurotransmitters, hormones and drugs, modulate the secretory function of pancreatic β-cells. This review is based on the analysis of clinical investigations characterizing the effects of non-glucose modulators of insulin secretion in healthy subjects, and of experimental studies testing the same modulators in islets isolated from normal human donors. The aim was to determine whether the information gathered in vitro can reliably be translated to the in vivo situation. The comparison evidenced both convincing similarities and areas of discordance. The lack of coherence generally stems from the use of exceedingly high concentrations of test agents at too high or too low glucose concentrations in vitro, which casts doubts on the physiological relevance of a number of observations made in isolated islets. Future projects resorting to human islets should avoid extreme experimental conditions, such as oversized stimulations or inhibitions of β-cells, which are unlikely to throw light on normal insulin secretion and contribute to the elucidation of its defects.

Glucocorticoid receptor wields chromatin interactions to tune transcription for cytoskeleton stabilization in podocytes

Elucidating transcription mediated by the glucocorticoid receptor (GR) is crucial for understanding the role of glucocorticoids (GCs) in the treatment of diseases. Podocyte is a useful model for studying GR regulation because GCs are the primary medication for podocytopathy. In this study, we integrated data from transcriptome, transcription factor binding, histone modification, and genome topology. Our data reveals that the GR binds and activates selective regulatory elements in podocyte. The 3D interactome captured by HiChIP facilitates the identification of remote targets of GR. We found that GR in podocyte is enriched at transcriptional interaction hubs and super-enhancers. We further demonstrate that the target gene of the top GR-associated super-enhancer is indispensable to the effective functioning of GC in podocyte. Our findings provided insights into the mechanisms underlying the protective effect of GCs on podocyte, and demonstrate the importance of considering transcriptional interactions in order to fine-map regulatory networks of GR.

Glucocorticoid signaling in pancreatic islets modulates gene regulatory programs and genetic risk of type 2 diabetes

Glucocorticoids are key regulators of glucose homeostasis and pancreatic islet function, but the gene regulatory programs driving responses to glucocorticoid signaling in islets and the contribution of these programs to diabetes risk are unknown. In this study we used ATAC-seq and RNA-seq to map chromatin accessibility and gene expression from eleven primary human islet samples cultured in vitro with the glucocorticoid dexamethasone at multiple doses and durations. We identified thousands of accessible chromatin sites and genes with significant changes in activity in response to glucocorticoids. Chromatin sites up-regulated in glucocorticoid signaling were prominently enriched for glucocorticoid receptor binding sites and up-regulated genes were enriched for ion transport and lipid metabolism, whereas down-regulated chromatin sites and genes were enriched for inflammatory, stress response and proliferative processes. Genetic variants associated with glucose levels and T2D risk were enriched in glucocorticoid-responsive chromatin sites, including fine-mapped variants at 51 known signals. Among fine-mapped variants in glucocorticoid-responsive chromatin, a likely casual variant at the 2p21 locus had glucocorticoid-dependent allelic effects on beta cell enhancer activity and affected SIX2 and SIX3 expression. Our results provide a comprehensive map of islet regulatory programs in response to glucocorticoids through which we uncover a role for islet glucocorticoid signaling in mediating genetic risk of T2D.

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.

Peripheral metabolic effects of ozone exposure in healthy and diabetic rats on normal or high-cholesterol diet

Epidemiological studies show that individuals with underlying diabetes and diet-associated ailments are more susceptible than healthy individuals to adverse health effects of air pollution. Exposure to air pollutants can induce metabolic stress and increase cardiometabolic disease risk. Using male Wistar and Wistar-derived Goto-Kakizaki (GK) rats, which exhibit a non-obese type-2 diabetes phenotype, we investigated whether two key metabolic stressors, type-2 diabetes and a high-cholesterol atherogenic diet, exacerbate ozone-induced metabolic effects. Rats were fed a normal control diet (ND) or high-cholesterol diet (HCD) for 12 weeks and then exposed to filtered air or 1.0-ppm ozone (6 h/day) for 1 or 2 days. Metabolic responses were analyzed at the end of each day and after an 18-h recovery period following the 2-day exposure. In GK rats, baseline hyperglycemia and glucose intolerance were exacerbated by HCD vs. ND and by ozone vs. air. HCD also resulted in higher insulin in ozone-exposed GK rats and circulating lipase, aspartate transaminase, and alanine transaminase in all groups (Wistar>GK). Histopathological effects induced by HCD in the liver, which included macrovesicular vacuolation and hepatocellular necrosis, were more severe in Wistar vs. GK rats. Liver gene expression in Wistar and GK rats fed ND showed numerous strain differences, including evidence of increased lipid metabolizing activity and ozone-induced alterations in glucose and lipid transporters, specifically in GK rats. Collectively, these findings indicate that peripheral metabolic alterations induced by diabetes and high-cholesterol diet can enhance susceptibility to the metabolic effects of inhaled pollutants.

4-Phenylbutyric acid protects islet β cell against cellular damage induced by glucocorticoids

This study, using the MIN6 cell line, examines the effect of glucocorticoids (GCs) on the expression and protein levels of endoplasmic reticulum stress (ERS) related genes. Furthermore, we evaluated the protective role of 4-phenylbutyric acid (4-PBA) on the aforesaid GCs induced changes. Pancreatic islet MIN6 cells were treated with dexamethasone (DEX) at distinct concentrations (0.1 μmol/L and 0.5 μmol/L) for different periods (1 h, 4 h, 12 h, and 24 h). The mRNA and protein levels of ERS related genes were measured using real-time qPCR (qRT-PCR) and western blotting. Similar evaluations were also carried out for the cells treated with 4-PBA combined with DEX. Upon DEX intervention which induces the unfolded protein response (UPR), the expression levels of BIP, ATF6, IRE1, and PERK increased in the MIN6 cells, both in concentration and time-dependent manner. Similarly, ERS associated gene CHOP, which is involved in the apoptotic pathway, also showed increased levels both in concentration and time-dependent manner. However, treatment with 4-PBA decreased the expression levels of ERS related proteins. Quantitative analysis found that all these results were statistically significant (P < 0.05). GCs markedly activates the ERS in the MIN6 cell line in vitro, however, this effect can be significantly alleviated upon treatment with 4-PBA.

Molecular Mechanisms of Glucocorticoid-Induced Insulin Resistance

Glucocorticoids (GCs) are steroids secreted by the adrenal cortex under the hypothalamic-pituitary-adrenal axis control, one of the major neuro-endocrine systems of the organism. These hormones are involved in tissue repair, immune stability, and metabolic processes, such as the regulation of carbohydrate, lipid, and protein metabolism. Globally, GCs are presented as ‘flight and fight’ hormones and, in that purpose, they are catabolic hormones required to mobilize storage to provide energy for the organism. If acute GC secretion allows fast metabolic adaptations to respond to danger, stress, or metabolic imbalance, long-term GC exposure arising from treatment or Cushing’s syndrome, progressively leads to insulin resistance and, in fine, cardiometabolic disorders. In this review, we briefly summarize the pharmacological actions of GC and metabolic dysregulations observed in patients exposed to an excess of GCs. Next, we describe in detail the molecular mechanisms underlying GC-induced insulin resistance in adipose tissue, liver, muscle, and to a lesser extent in gut, bone, and brain, mainly identified by numerous studies performed in animal models. Finally, we present the paradoxical effects of GCs on beta cell mass and insulin secretion by the pancreas with a specific focus on the direct and indirect (through insulin-sensitive organs) effects of GCs. Overall, a better knowledge of the specific action of GCs on several organs and their molecular targets may help foster the understanding of GCs’ side effects and design new drugs that possess therapeutic benefits without metabolic adverse effects.

Association between Neutrophilic Granulocyte Percentage and Diabetes Mellitus in Cushing's Syndrome Patients: A Cross-Sectional Study

BACKGROUND

Glucose metabolism is frequently impaired in patients with Cushing's syndrome (CS) due to chronic exposure to excess glucocorticoids. Inflammation plays an essential role in the pathophysiology of diabetes mellitus (DM). The present study aimed to investigate the potential associations of inflammatory blood cell parameters, including white blood cell (WBC) count, neutrophil count, neutrophilic granulocyte percentage (NEUT%), lymphocyte count (LYM), and lymphocyte proportion (LYM%), with diabetes mellitus in Cushing's syndrome patients.

MATERIALS AND METHODS

The cross-sectional study was conducted in Zhongshan Hospital of Fudan University, China. A total of 150 patients with Cushing's syndrome were retrospectively screened from 2017 to 2019. The demographic data, clinical data, and blood samples (lipids, adrenal, glucose, and inflammatory blood cell parameters) were recorded. Statistical analyses were carried out by using the SPSS software package, version 13.0.

RESULTS

In this study, the prevalence of diabetes mellitus was 38.7% in patients with Cushing's syndrome. Patients with DM had higher WBC, neutrophil, NEUT% levels than patients without DM (p < 0.05). As the NEUT% increased, a stepwise increase in glucose and glycated hemoglobin (HbA1c) level was observed. In addition, in the multivariate logistic regression, NEUT% was a significant independent risk factor for DM, regardless of gender, age, body mass index (BMI), and triglyceride and 12 midnight cortisol (12 MN cortisol) level (OR = 2.542, 95% CI 1.337-4.835, p < 0.001).

CONCLUSIONS

In conclusion, elevated NEUT% level was linked to diabetes in patients with Cushing's syndrome. The neutrophilic granulocyte percentage may be referred to as a new predictor for diabetes in Cushing's syndrome patients.

The Association of Cortisol Excretion with Weight and Metabolic Parameters in Nondiabetic Patients with Morbid Obesity

INTRODUCTION

Cortisol is involved in the regulation of gluconeogenesis and glucose utilization. In morbid obesity (MO), the association of cortisol excretion with metabolic parameters is not well-characterized. In our study, we evaluated cortisol excretion in nondiabetic subjects with MO and its effect on glucose metabolism.

METHODS

We included 1,249 nondiabetic patients with MO (79.8% females, mean BMI 44.9 ± 6.5 kg/m2, mean age 38 ± 11 years). Anthropometric data and cardiovascular risk factors were assessed, and an oral glucose tolerance test for calculation of insulin resistance was performed. Cortisol excretion was assessed on 2 consecutive days (24 h urine specimens).

RESULTS

Regarding cortisol excretion, patients were divided into 3 tertiles (urinary cortisol ≤51.6, >51.6 and <117.6, and ≥117.6 μg/24 h, respectively). Patients in the highest tertile were younger (p = 0.003), more obese (BMI: p = 0.040), had lower diastolic blood pressure ([DBP]; p = 0.012), lower total (p = 0.032) and LDL cholesterol (p = 0.021), fasting (p = 0.049) and 2-h glycemia (p = 0.028), 2-h insulinemia (p = 0.020), and HbA1c (p < 0.001), and a higher estimated glomerular filtration rate (eGFR) (p < 0.001). The glucose (p < 0.001) and insulin (p = 0.011) area under the curve (AUC) were also lower. Urinary cortisol excretion adjusted for age, sex, and eGFR was positively correlated with body weight (BW, beta = 0.076, p = 0.004) and overall glucose tolerance (oral disposition index, beta = 0.090, p = 0.011), and negatively with HbA1c (beta = -0.179, p < 0.001), 2-h glycemia (beta = -0.075, p = 0.032), AUC glucose (beta = -0.103, p = 0.002), and DBP (beta = -0.139, p < 0.001). HbA1c, BW, and DBP remained significant after multivariable analysis.

DISCUSSION/CONCLUSION

Despite being more obese, patients with higher cortisol excretion have a more favorable metabolic profile. These results deserve further attention regarding the respective mechanisms.

The difference between steroid diabetes mellitus and type 2 diabetes mellitus: a whole-body 18F-FDG PET/CT study

AIMS

Steroid diabetes mellitus (SDM) is a metabolic syndrome caused by an increase in glucocorticoids, and its pathogenesis is unclear. ¹⁸F-FDG PET/CT can reflect the glucose metabolism of tissues and organs under living conditions. Here, PET/CT imaging of SDM and type 2 diabetes mellitus (T2DM) rats was used to visualize changes in glucose metabolism in the main glucose metabolizing organs and investigate the pathogenesis of SDM.

METHODS

SDM and T2DM rat models were established. During this time, PET/CT imaging was used to measure the %ID/g value of skeletal muscle and liver to evaluate glucose uptake. The pancreatic, skeletal muscle and liver were analyzed by immunohistochemistry.

RESULTS

SDM rats showed increased fasting blood glucose and insulin levels, hyperplasia of islet α and β cells, increased FDG uptake in skeletal muscle accompanied by an up-regulation of PI3Kp85α, IRS-1, and GLUT4, no significant changes in liver uptake, and that glycogen storage in the liver and skeletal muscle increased. T2DM rats showed atrophy of pancreatic islet β cells and decreased insulin levels, significantly reduced FDG uptake and glycogen storage in skeletal muscle and liver.

CONCLUSIONS

The pathogenesis of SDM is different from that of T2DM. The increased glucose metabolism of skeletal muscle may be related to the increased compensatory secretion of insulin. Glucocorticoids promote the proliferation of islet α cells and cause an increase in gluconeogenesis in the liver, which may cause increased blood glucose.

Glucagon-Like Peptide-1 (GLP-1) in the Integration of Neural and Endocrine Responses to Stress

Glucagon like-peptide 1 (GLP-1) within the brain is produced by a population of preproglucagon neurons located in the caudal nucleus of the solitary tract. These neurons project to the hypothalamus and another forebrain, hindbrain, and mesolimbic brain areas control the autonomic function, feeding, and the motivation to feed or regulate the stress response and the hypothalamic-pituitary-adrenal axis. GLP-1 receptor (GLP-1R) controls both food intake and feeding behavior (hunger-driven feeding, the hedonic value of food, and food motivation). The activation of GLP-1 receptors involves second messenger pathways and ionic events in the autonomic nervous system, which are very relevant to explain the essential central actions of GLP-1 as neuromodulator coordinating food intake in response to a physiological and stress-related stimulus to maintain homeostasis. Alterations in GLP-1 signaling associated with obesity or chronic stress induce the dysregulation of eating behavior. This review summarized the experimental shreds of evidence from studies using GLP-1R agonists to describe the neural and endocrine integration of stress responses and feeding behavior.

Chemical Biology Toolbox for Studying Pancreatic Islet Function - A Perspective

The islets of Langerhans represent one of the many complex endocrine organs in mammals. Traditionally, islet function is studied by a mixture of physiological, cell biological, and molecular biological methods. Recently, novel techniques stemming from the ever-increasing toolbox provided by chemical laboratories have been added to the repertoire. Many emerging techniques will soon be available to manipulate and monitor islet function at the single-cell level and potentially in intact model animals, as well as in isolated human islets. Here, we review the most current small-molecule-based and genetically encoded molecular tool sets available to study islet function. We provide an outlook regarding future tool developments that will impact islet research, with a special focus on the interplay between different islet cell types.

Cancer Biology and Prevention in Diabetes

The available evidence suggests a complex relationship between diabetes and cancer. Epidemiological data suggest a positive correlation, however, in certain types of cancer, a more complex picture emerges, such as in some site-specific cancers being specific to type I diabetes but not to type II diabetes. Reports share common and differential mechanisms which affect the relationship between diabetes and cancer. We discuss the use of antidiabetic drugs in a wide range of cancer therapy and cancer therapeutics in the development of hyperglycemia, especially antineoplastic drugs which often induce hyperglycemia by targeting insulin/IGF-1 signaling. Similarly, dipeptidyl peptidase 4 (DPP-4), a well-known target in type II diabetes mellitus, has differential effects on cancer types. Past studies suggest a protective role of DPP-4 inhibitors, but recent studies show that DPP-4 inhibition induces cancer metastasis. Moreover, molecular pathological mechanisms of cancer in diabetes are currently largely unclear. The cancer-causing mechanisms in diabetes have been shown to be complex, including excessive ROS-formation, destruction of essential biomolecules, chronic inflammation, and impaired healing phenomena, collectively leading to carcinogenesis in diabetic conditions. Diabetes-associated epithelial-to-mesenchymal transition (EMT) and endothelial-to-mesenchymal transition (EndMT) contribute to cancer-associated fibroblast (CAF) formation in tumors, allowing the epithelium and endothelium to enable tumor cell extravasation. In this review, we discuss the risk of cancer associated with anti-diabetic therapies, including DPP-4 inhibitors and SGLT2 inhibitors, and the role of catechol-o-methyltransferase (COMT), AMPK, and cell-specific glucocorticoid receptors in cancer biology. We explore possible mechanistic links between diabetes and cancer biology and discuss new therapeutic approaches.

Glucose metabolism in Cushing's syndrome

PURPOSE OF REVIEW

Impairment of glucose metabolism is commonly encountered in Cushing's syndrome. It is the source of significant morbidity and mortality even after successful treatment of Cushing's. This review is to understand the recent advances in understanding the pathophysiology of diabetes mellitus from excess cortisol.

RECENT FINDINGS

In-vitro studies have led to significant advancement in understanding the molecular effects of cortisol on glucose metabolism. Some of these findings have been translated with human data. There is marked reduction in insulin action and glucose disposal with a concomitant, insufficient increase in insulin secretion. Cortisol has a varied effect on adipose tissue, with increased lipolysis in subcutaneous adipose tissue in the extremities, and increased lipogenesis in visceral and subcutaneous truncal adipose tissue.

SUMMARY

Cushing's syndrome results in marked impairment in insulin action and glucose disposal resulting in hyperglycemia. Further studies are required to understand the effect on incretin secretion and action, gastric emptying, and its varied effect on adipose tissue.

Independent roles of beta-adrenergic and glucocorticoid receptors in systemic and pulmonary effects of ozone

Background: The release of catecholamines is preceded by glucocorticoids during a stress response. We have shown that ozone-induced pulmonary responses are mediated through the activation of stress hormone receptors.Objective: To examine the interdependence of beta-adrenergic (βAR) and glucocorticoid receptors (GRs), we inhibited βAR while inducing GR or inhibited GR while inducing βAR and examined ozone-induced stress response.Methods: Twelve-week-old male Wistar-Kyoto rats were pretreated daily with saline or propranolol (PROP; βAR-antagonist; 10 mg/kg-i.p.; starting 7-d prior to exposure) followed-by saline or dexamethasone (DEX) sulfate (GR-agonist; 0.02 mg/kg-i.p.; starting 1-d prior to exposure) and exposed to air or 0.8 ppm ozone (4 h/d × 2-d). In a second experiment, rats were similarly pretreated with corn-oil or mifepristone (MIFE; GR-antagonist, 30 mg/kg-s.c.) followed by saline or clenbuterol (CLEN; β₂AR-agonist; 0.02 mg/kg-i.p.) and exposed.Results: DEX and PROP + DEX decreased adrenal, spleen and thymus weights in all rats. DEX and MIFE decreased and increased corticosterone, respectively. Ozone-induced pulmonary protein leakage, inflammation and IL-6 increases were inhibited by PROP or PROP + DEX and exacerbated by CLEN or CLEN + MIFE. DEX and ozone-induced while MIFE reversed lymphopenia (MIFE > CLEN + MIFE). DEX exacerbated while PROP, MIFE, or CLEN + MIFE inhibited ozone-induced hyperglycemia and glucose intolerance. Ozone inhibited glucose-mediated insulin release.Conclusions: In summary, 1) activating βAR, even with GR inhibition, exacerbated and inhibiting βAR, even with GR activation, attenuated ozone-induced pulmonary effects; and 2) activating GR exacerbated ozone systemic effects, but with βAR inhibition, this exacerbation was less remarkable. These data suggest the independent roles of βAR in pulmonary and dependent roles of βAR and GR in systemic effects of ozone.

Perinatal programming of metabolic diseases: The role of glucocorticoids

The worldwide increase in metabolic diseases has urged the scientific community to improve our understanding about the mechanisms underlying its cause and effects. A well supported area of studies had related maternal stress with early programming to the later metabolic diseases. Mechanisms upon origins of metabolic disturbances are not yet fully understood, even though stressful factors rising glucocorticoids have been put out as pivotal trigger by programming metabolic diseases as long-term consequence. Considering energy balance and glucose homeostasis, by producing and/or sensing regulator signals, hypothalamus-pituitary-adrenal axis and endocrine pancreas are directly affected by glucocorticoids excess. We focus on the evidences reporting the role of increased glucocorticoids due to perinatal insults on the physiological systems involved in the metabolic homeostasis and in the target organs such as endocrine pancreas, white adipose tissue and blood vessels. Besides, we review some mechanisms underlining the malprogramming of type 2 diabetes, obesity and hypertension. Studies on this field are currently ongoing and even there is a good understanding regarding the effects of glucocorticoids addressing metabolic diseases, few is known about the relationship between maternal insults rising glucocorticoids to pups' metabolic disturbances, a thorough understanding about that may provide pivotal clinical clues regarding those disorders.

Glucocorticoid Metabolism in Obesity and Following Weight Loss

Glucocorticoids are steroid hormones produced by the adrenal cortex and are essential for the maintenance of various metabolic and homeostatic functions. Their function is regulated at the tissue level by 11β-hydroxysteroid dehydrogenases and they signal through the glucocorticoid receptor, a ligand-dependent transcription factor. Clinical observations have linked excess glucocorticoid levels with profound metabolic disturbances of intermediate metabolism resulting in abdominal obesity, insulin resistance and dyslipidaemia. In this review, we discuss the physiological mechanisms of glucocorticoid secretion, regulation and function, and survey the metabolic consequences of excess glucocorticoid action resulting from elevated release and activation or up-regulated signaling. Finally, we summarize the reported impact of weight loss by diet, exercise, or bariatric surgery on circulating and tissue-specific glucocorticoid levels and examine the therapeutic possibility of reversing glucocorticoid-associated metabolic disorders.

Immune System Remodelling by Prenatal Betamethasone: Effects on β-Cells and Type 1 Diabetes

Type 1 diabetes (T1D) is a multifactorial disease of unknown aetiology. Studies focusing on environment-related prenatal changes, which might have an influence on the development of T1D, are still missing. Drugs, such as betamethasone, are used during this critical period without exploring possible effects later in life. Betamethasone can interact with the development and function of the two main players in T1D, the immune system and the pancreatic β-cells. Short-term or persistent changes in any of these two players may influence the initiation of the autoimmune reaction against β-cells. In this review, we focus on the ability of betamethasone to induce alterations in the immune system, impairing the recognition of autoantigens. At the same time, betamethasone affects β-cell gene expression and apoptosis rate, reducing the danger signals that will attract unwanted attention from the immune system. These effects may synergise to hinder the autoimmune attack. In this review, we compile scattered evidence to provide a better understanding of the basic relationship between betamethasone and T1D, laying the foundation for future studies on human cohorts that will help to fully grasp the role of betamethasone in the development of T1D.

Diabetes mellitus among adult survivors of childhood acute lymphoblastic leukemia: A report from the St. Jude Lifetime Cohort Study

BACKGROUND

Greater than one-half of children who are treated for acute lymphoblastic leukemia (ALL) develop ≥1 treatment-related medical conditions in their lifetime, many of which are known risk factors for diabetes mellitus. In the current study, the authors evaluated the prevalence and risk factors of diabetes mellitus among clinically assessed adult survivors of childhood ALL METHODS: The authors performed a retrospective evaluation of data from survivors of ALL and community controls who were enrolled in the St. Jude Lifetime Cohort Study between October 1, 2007, and June 30, 2016. Participants were adults with ≥10 years of survival of childhood ALL and community controls who completed clinical and laboratory evaluations. Data for the current analysis were abstracted from medical records. Exposures evaluated herein included chemotherapy and radiation exposures and medical history, including drug-induced diabetes mellitus.

RESULTS

Of 1360 eligible adults who were ≥10-year survivors of childhood ALL, a total of 1044 completed the evaluations; these individuals had a mean age of 33.97±9.14 years and 50.86% were male. The 368 controls, 45.65% of whom were male, had a mean age of 35.33±10.21 years. Type 2 diabetes mellitus (T2DM) was found in approximately 7.47% of survivors and 3.80% of controls (odds ratio [OR], 2.07; 95% CI, 1.11-3.87). In adjusted models, among survivors, older age (OR, 1.05 for each additional year; 95% CI, 1.02-1.08), body mass index ≥30 kg/m² (OR, 7.40; 95% CI, 2.61-20.97), and drug-induced diabetes mellitus occurring during ALL therapy (OR, 4.67; 95% CI, 2.53-8.61) were found to be associated with T2DM.

CONCLUSIONS

Adult survivors of childhood ALL are at an increased risk of T2DM. Adult survivors of childhood ALL who are of older age, with an overweight or obese body mass index, and/or who developed drug-induced diabetes mellitus during treatment should be closely monitored for T2DM during long-term follow-up.

Hippo/Mst1 overexpression induces mitochondrial death in head and neck squamous cell carcinoma via activating β-catenin/Drp1 pathway

Mammalian Ste20-like kinase 1 (Mst1) is associated with cell apoptosis. In the current study, we explored the regulatory effects of Mst1 on squamous cell carcinoma of the head and neck (SCCHN) in vitro. SCCHN Cal27 cells and Tu686 cells were transfected with adenovirus-loaded Mst1 to detect the role of Mst1 in cell viability. Then, siRNA against Drp1 was transfected into cells to evaluate the influence of mitochondrial fission in cancer survival. Our data illustrated that Mst1 overexpression promoted SCCHN Cal27 cell and Tu686 cell death via activating mitochondria-related apoptosis. Cells transfected with adenovirus-loaded Mst1 have increased expression of DRP1 and higher DRP1 promoted mitochondrial fission. Active mitochondrial fission mediated mitochondrial damage, as evidenced by increased mitochondrial oxidative stress, decreased mitochondrial energy production, and reduced mitochondrial respiratory complex function. Moreover, Mst1 overexpression triggered mitochondria-dependent cell apoptosis via DRP1-related mitochondrial fission. Further, we found that Mst1 overexpression controlled mitochondrial fission via the β-catenin/DRP1 pathways; inhibition of β-catenin and/or knockdown of DRP1 abolished the pro-apoptotic effects of Mst1 overexpression on SCCHN Cal27 cells and Tu686 cells, leading to the survival of cancer cells in vitro. In sum, our results illustrate that Mst1/β-catenin/DRP1 axis affects SCCHN Cal27 cell and Tu686 cell viability via controlling mitochondrial dynamics balance. This finding identifies Mst1 activation might be an effective therapeutic target for the treatment of SCCHN.

Mst1 deletion reduces hyperglycemia-mediated vascular dysfunction via attenuating mitochondrial fission and modulating the JNK signaling pathway

Diabetes is a leading cause of microvascular complications, such as nephropathy and retinopathy. Recent studies have proposed that hyperglycemia-induced endothelial cell dysfunction is modulated by mitochondrial stress. Therefore, our experiment was to detect the upstream mediator of mitochondrial stress in hyperglycemia-treated endothelial cells with a focus on macrophage-stimulating 1 (Mst1) and mitochondrial fission. Our data illuminated that hyperglycemia incubation reduced cell viability, as well as increased apoptosis ratio in endothelial cell, and this alteration seemed to be associated with Mst1 upregulation. Inhibition of Mst1 via transfection of Mst1 siRNA into an endothelial cell could sustain cell viability and maintain mitochondrial function. At the molecular levels, endothelial cell death was accompanied with the activation of mitochondrial oxidative stress, mitochondrial apoptosis, and mitochondrial fission. Genetic ablation of Mst1 could reduce mitochondrial oxidative injury, block mitochondrial apoptosis, and repress mitochondrial fission. Besides, we also found Mst1 triggered mitochondrial dysfunction as well as endothelial cell damage through augmenting JNK pathway. Suppression of JNK largely ameliorated the protective actions of Mst1 silencing on hyperglycemia-treated endothelial cells and sustain mitochondrial function. The present study identifies Mst1 as a primary key mediator for hyperglycemia-induced mitochondrial damage and endothelial cell dysfunction. Increased Mst1 impairs mitochondrial function and activates endothelial cell death via opening mitochondrial death pathway through JNK.

Sirt3 modulate renal ischemia-reperfusion injury through enhancing mitochondrial fusion and activating the ERK-OPA1 signaling pathway

Mitochondrial fusion is linked to heart and liver ischemia-reperfusion (IR) insult. Unfortunately, there is no report to elucidate the detailed influence of mitochondrial fusion in renal IR injury. This study principally investigated the mechanism by which mitochondrial fusion protected kidney against IR injury. Our results indicated that sirtuin 3 (Sirt3) was inhibited after renal IR injury in vivo and in vitro. Overexpression of Sirt3 improved kidney function, modulated oxidative injury, repressed inflammatory damage, and reduced tubular epithelial cell apoptosis. The molecular investigation found that Sirt3 overexpression attenuated IR-induced mitochondrial damage in renal tubular epithelial cells, as evidenced by decreased reactive oxygen species production, increased antioxidants sustained mitochondrial membrane potential, and inactivated mitochondria-initiated death signaling. In addition, our information also illuminated that Sirt3 maintained mitochondrial homeostasis against IR injury by enhancing optic atrophy 1 (OPA1)-triggered fusion of mitochondrion. Inhibition of OPA1-induced fusion repressed Sirt3 overexpression-induced kidney protection, leading to mitochondrial dysfunction. Further, our study illustrated that OPA1-induced fusion could be affected through ERK; inhibition of ERK abolished the regulatory impacts of Sirt3 on OPA1 expression and mitochondrial fusion, leading to mitochondrial damage and tubular epithelial cell apoptosis. Altogether, our results suggest that renal IR injury is closely associated with Sirt3 downregulation and mitochondrial fusion inhibition. Regaining Sirt3 and/or activating mitochondrial fission by modifying the ERK-OPA1 cascade may represent new therapeutic modalities for renal IR injury.

Mst1 contributes to nasal epithelium inflammation via augmenting oxidative stress and mitochondrial dysfunction in a manner dependent on Nrf2 inhibition

Nasal epithelium inflammation plays an important role in transmitting and amplifying damage signals for the lower airway. However, the molecular basis of nasal epithelium inflammation damage has not been fully addressed. Mst1 is reported to modulate inflammation via multiple effects. Thus, the aim of our study is to understand the pathological mechanism underlying Mst1-related nasal epithelium inflammation in vitro. Our result indicated that Mst1 expression was rapidly increased in response to tumor necrosis factor-α (TNF-α) treatment in vitro and this effect was a dose-dependent manner. Interestingly, knockdown of Mst1 via transfecting small interfering RNA markedly reversed cell viability in the presence of TNF-α. Further, we found that Mst1 deficiency reduced cellular oxidative stress and attenuated mitochondrial dysfunction, as evidenced by reversed mitochondrial complex-I activity, decreased mitochondrial permeability transition pore opening rate, and stabilized mitochondrial membrane potential. Besides, we found that Nrf2 expression was increased after deletion of Mst1 whereas silencing of Nrf2 abolished the protective effects of Mst1 deletion on nasal epithelium survival and mitochondrial homeostasis. Moreover, Nrf2 overexpression also protected nasal epithelium against TNF-α-induced inflammation damage. Altogether, our data confirm that the Mst1 activation and Nrf2 downregulation seem to be the potential mechanisms responsible for the inflammation-mediated injury in nasal epithelium via mediating mitochondrial damage and cell oxidative stress.

Matrine promotes apoptosis in SW480 colorectal cancer cells via elevating MIEF1-related mitochondrial division in a manner dependent on LATS2-Hippo pathway

Matrine, an alkaloid compound isolated from Sophora flavescens Ait, has been shown to exert cancer-killing actions in a variety of tumors; however, its anticancer mechanism in colorectal cancer (CRC) is not clear. The goal of our study was to characterize the anticancer effects and molecular mechanisms of matrine in SW480 CRC cells in vitro. Matrine treatment reduced mitochondrial metabolic function and ATP levels, repressed mitochondrial membrane potential, evoked mitochondrial reactive oxygen species accumulation, and promoted cyt-c-related mitochondrial apoptosis activation. In addition, we found that matrine treatment activated mitochondrial fission through upregulating mitochondrial elongation factor 1 (MIEF1); silencing of MIEF1 prevented matrine-mediated mitochondrial damage and reversed the decrease in SW480 cell viability. Moreover, matrine treatment affected MIEF1 expression via the large tumor suppressor-2 (LATS2)-Hippo axis, and LATS2 deficiency suppressed the anticancer actions exerted by matrine on SW480 cancer cells. In summary, we show for the first time that matrine inhibits SW480 cell survival by activating MIEF1-related mitochondrial division via the LATS2-Hippo pathway. These findings explain the anticancer mechanisms of matrine in CRC and also identify the LATS2-MIEF1 signaling pathway as an effective target for the treatment of CRC.

Mathematical Modelling of Endocrine Systems

Hormone rhythms are ubiquitous and essential to sustain normal physiological functions. Combined mathematical modelling and experimental approaches have shown that these rhythms result from regulatory processes occurring at multiple levels of organisation and require continuous dynamic equilibration, particularly in response to stimuli. We review how such an interdisciplinary approach has been successfully applied to unravel complex regulatory mechanisms in the metabolic, stress, and reproductive axes. We discuss how this strategy is likely to be instrumental for making progress in emerging areas such as chronobiology and network physiology. Ultimately, we envisage that the insight provided by mathematical models could lead to novel experimental tools able to continuously adapt parameters to gradual physiological changes and the design of clinical interventions to restore normal endocrine function.

Glucocorticoids and checkpoint tyrosine kinase inhibitors stimulate rat pancreatic beta cell proliferation differentially

Cell therapy for diabetes could benefit from the identification of small-molecule compounds that increase the number of functional pancreatic beta cells. Using a newly developed screening assay, we previously identified glucocorticoids as potent stimulators of human and rat beta cell proliferation. We now compare the stimulatory action of these steroid hormones to a selection of checkpoint tyrosine kinase inhibitors that were also found to activate the cell cycle-in beta cells and analyzed their respective effects on DNA-synthesis, beta cell numbers and expression of cell cycle regulators. Our data using glucocorticoids in combination with a receptor antagonist, mifepristone, show that 48h exposure is sufficient to allow beta cells to pass the cell cycle restriction point and to become committed to cell division regardless of sustained glucocorticoid-signaling. To reach the end-point of mitosis another 40h is required. Within 14 days glucocorticoids stimulate up to 75% of the cells to undergo mitosis, which indicates that these steroid hormones act as proliferation competence-inducing factors. In contrast, by correlating thymidine-analogue incorporation to changes in absolute cell numbers, we show that the checkpoint kinase inhibitors, as compared to glucocorticoids, stimulate DNA-synthesis only during a short time-window in a minority of cells, insufficient to give a measurable increase of beta cell numbers. Glucocorticoids, but not the kinase inhibitors, were also found to induce changes in the expression of checkpoint regulators. Our data, using checkpoint kinase-specific inhibitors further point to a role for Chk1 and Cdk1 in G1/S transition and progression of beta cells through the cell cycle upon stimulation with glucocorticoids.

Steroid-induced hyperglycemia: An underdiagnosed problem or clinical inertia? A narrative review

Corticosteroids are widely diffused drugs. An important side effect is the impairment of glycemic control both in patients with known diabetes and in normoglycemic ones potentially leading to steroid-induced diabetes mellitus (SIDM). In this review based on papers released on PubMed, MEDLINE, and EMBASE from January 2015 to October 2017, we summarized and discussed main updates about the definition, the diagnosis, and the pathophysiology of steroid-induced hyperglycemia (SIH), with a look to new therapies. Main alterations responsible for the diabetogenic effect of corticosteroids are a negative impact on insulin sensitivity along with a derangement on insulin secretion, explaining the typical post-prandial hyperglycemia linked to the promotion of gluconeogenesis. An early and precise diagnosis of SIH and/or SIDM is necessary, but current criteria do not seem sensible enough. As an afterthought, the treatment should be reasoned and tailored according to proposed glycemic thresholds and patient comorbidities, choosing between antidiabetic oral drugs and insulin, the latter being preferable among hospitalized patients. SIDM and SIH are frequent problems, but often underdiagnosed due to old diagnostic criteria. Dedicated guidelines universally shared are mandatory in order to harmonize the treatment of these conditions, thus overtaking single therapeutic strategies mostly arising from literature.