Chronic ethanol consumption-induced pancreatic {beta}-cell dysfunction and apoptosis through glucokinase nitration and its down-regulation

Mitochondrial HKDC1 suppresses oxidative stress and apoptosis by regulating mitochondrial function in goose fatty liver

Different from human non-alcoholic fatty liver disease (NAFLD), goose fatty liver is physiological with no inflammation. Consistently, mitochondrial dysfunction, oxidative stress and apoptosis are rarely seen in goose fatty liver. Hexokinase domain-containing protein 1 (HKDC1) is involved in maintaining systemic glucose homeostasis, and its absence causes mitochondrial dysfunction. Here, we demonstrated that mitochondrial outer membrane-bound HKDC1 (mHKDC1) had an expression pattern different from that of whole-cell HKDC1 (wHKDC1). Data indicated that the protein level of whole-cell HKDC1 (wHKDC1) was increased but mHKDC1 was decreased in mouse fatty liver. Interestingly, both the protein levels of wHKDC1 and mHKDC1 were significantly increased in goose fatty liver. Treatment of goose or mouse hepatocytes with fatty liver-related factors could influence the expression of wHKDC1 and mHKDC1, but the influence on wHKDC1 was not identical to mHKDC1. HKDC1 overexpression in goose hepatocytes increased wHKDC1 and mHKDC1 expression, mitochondrial membrane potential (MMP), mitochondrial respiratory chain activity, and suppressed reactive oxygen species (ROS) generation, apoptosis and cytokine-cytokine receptor signaling pathway. In addition, mutations in mitochondrial signal peptide or activation domain of HKDC1 altered MMP or ROS levels. In conclusion, HKDC1, particularly mHKDC1, may protect goose fatty liver by regulating mitochondrial function, ROS generation, apoptosis, and inflammation-related pathways.

Interactions of genes with alcohol consumption affect insulin sensitivity and beta cell function

AIMS/HYPOTHESIS

Alcohol consumption has complex effects on diabetes and metabolic disease, but there is widespread heterogeneity within populations and the specific reasons are unclear. Genetic factors may play a role and warrant exploration. The aim of this study was to elucidate genetic variants modulating the impact of alcohol consumption on insulin sensitivity and pancreatic beta cell function within populations presenting normal glucose tolerance (NGT).

METHODS

We recruited 4194 volunteers in Nanjing, 854 in Jurong and an additional 5833 in Nanjing for Discovery cohorts 1 and 2 and a Validation cohort, respectively. We performed an OGTT on all participants, establishing a stringent NGT group, and then assessed insulin sensitivity and beta cell function. Alcohol consumption was categorised as abstinent, light-to-moderate (<210 g per week) or heavy (≥210 g per week). After excluding ineligible individuals, an exploratory genome-wide association study identified potential variants interacting with alcohol consumption in 1862 NGT individuals. These findings were validated in an additional cohort of 2169 NGT individuals. Cox proportional hazard regression was further employed to evaluate the effect of the interaction between the potential variants and alcohol consumption on the risk of type 2 diabetes within the UK Biobank cohort.

RESULTS

A significant correlation was observed between drinking levels and insulin sensitivity, accompanied by a consequent inverse relationship with insulin resistance and beta cell insulin secretion after adjusting for confounding factors in NGT individuals. However, no significant associations were noted in the disposition indexes. The interaction of variant rs56221195 with alcohol intake exhibited a pronounced effect on the liver insulin resistance index (LIRI) in the discovery set, corroborated in the validation set (combined p=1.32 × 10-11). Alcohol consumption did not significantly affect LIRI in rs56221195 wild-type (TT) carriers, but a strong negative association emerged in heterozygous (TA) and homozygous (AA) individuals. The rs56221195 variant also significantly interacts with alcohol consumption, influencing the total insulin secretion index INSR120 (the ratio of the AUC of insulin to glucose from 0 to 120 min) (p=2.06 × 10-9) but not disposition index. In the UK Biobank, we found a significant interaction between rs56221195 and alcohol consumption, which was linked to the risk of type 2 diabetes (HR 0.897, p=0.008).

CONCLUSIONS/INTERPRETATION

Our findings reveal the effects of the interaction of alcohol and rs56221195 on hepatic insulin sensitivity in NGT individuals. It is imperative to weigh potential benefits and detriments thoughtfully when considering alcohol consumption across diverse genetic backgrounds.

Effect of diabetes on mortality and liver transplantation in alcoholic liver cirrhotic patients with acute decompensation

BACKGROUND

Previous studies have investigated the influence of diabetes on alcoholic liver cirrhosis patients, leaving its impact unclear. Thus, we conducted a study to reveal the association of diabetes and clinical outcomes of such patients.

MATERIALS AND METHODS

We prospectively collected data from multicenter pertaining to 965 patients diagnosed with alcoholic liver cirrhosis, all of whom were admitted due to acute decompensation between 2015 and 2019. Risk of major precipitating factors and incidences of death or liver transplantation in patients with and without diabetes was comparatively assessed. Propensity score (PS) matching was performed at a 1:2 ratio for accurate comparisons.

RESULTS

The mean age was 53.4 years, and 81.0% of the patients were male. Diabetes was prevalent in 23.6% of the cohort and was positively correlated with hepatic encephalopathy and upper gastrointestinal bleeding, although not statistically significant. During a median follow-up of 903.5 person-years (PYs), 64 patients with and 171 without diabetes died or underwent liver transplantation, with annual incidence of 33.6/100 PYs and 24.0/100 PYs, respectively. In the PS-matched cohort, the incidence of death or liver transplantation was 36.8/100 PYs and 18.6/100 PYs in the diabetes and matched control group, respectively. After adjusting for various factors, coexisting diabetes significantly heightened the risk of death or liver transplantation in the short and long term, in addition to prolonged prothrombin time, low serum albumin, elevated total bilirubin and creatinine, and decreased serum sodium levels.

CONCLUSIONS

Diabetes increases the risk of death or liver transplantation in patients with alcoholic liver cirrhosis.

Current Knowledge on the Pathophysiology of Lean/Normal-Weight Type 2 Diabetes

Since early times, being overweight and obesity have been associated with impaired glucose metabolism and type 2 diabetes (T2D). Similarly, a less frequent adult-onset diabetes in low body mass index (BMI) people has been known for many decades. This form is mainly found in developing countries, whereby the largest increase in diabetes incidence is expected in coming years. The number of non-obese patients with T2D is also on the rise among non-white ethnic minorities living in high-income Western countries due to growing migratory flows. A great deal of energy has been spent on understanding the mechanisms that bind obesity to T2D. Conversely, the pathophysiologic features and factors driving the risk of T2D development in non-obese people are still much debated. To reduce the global burden of diabetes, we need to understand why not all obese people develop T2D and not all those with T2D are obese. Moreover, through both an effective prevention and the implementation of an individualized clinical management in all people with diabetes, it is hoped that this will help to reduce this global burden. The purpose of this review is to take stock of current knowledge about the pathophysiology of diabetes not associated to obesity and to highlight which aspects are worthy of future studies.

Impact of Reactive Species on Amino Acids-Biological Relevance in Proteins and Induced Pathologies

This review examines the impact of reactive species RS (of oxygen ROS, nitrogen RNS and halogens RHS) on various amino acids, analyzed from a reactive point of view of how during these reactions, the molecules are hydroxylated, nitrated, or halogenated such that they can lose their capacity to form part of the proteins or peptides, and can lose their function. The reactions of the RS with several amino acids are described, and an attempt was made to review and explain the chemical mechanisms of the formation of the hydroxylated, nitrated, and halogenated derivatives. One aim of this work is to provide a theoretical analysis of the amino acids and derivatives compounds in the possible positions. Tyrosine, methionine, cysteine, and tryptophan can react with the harmful peroxynitrite or ^•OH and ^•NO₂ radicals and glycine, serine, alanine, valine, arginine, lysine, tyrosine, histidine, cysteine, methionine, cystine, tryptophan, glutamine and asparagine can react with hypochlorous acid HOCl. These theoretical results may help to explain the loss of function of proteins subjected to these three types of reactive stresses. We hope that this work can help to assess the potential damage that reactive species can cause to free amino acids or the corresponding residues when they are part of peptides and proteins.

Associations between local acidosis induced by renal LDHA and renal fibrosis and mitochondrial abnormalities in patients with diabetic kidney disease

During the progression of diabetic kidney disease (DKD), renal lactate metabolism is rewired. The relationship between alterations in renal lactate metabolism and renal fibrosis in patients with diabetes has only been partially established due to a lack of biopsy tissues from patients with DKD and the intricate mechanism of lactate homeostasis. The role of lactate dehydrogenase A (LDHA)-mediated lactate generation in renal fibrosis and dysfunction in human and animal models of DKD was explored in this study. Measures of lactate metabolism (urinary lactate levels and LDHA expression) and measures of DKD progression (estimated glomerular filtration rate and Wilms' tumor-1 expression) were strongly negatively correlated in patients with DKD. Experiments with streptozotocin-induced DKD rat models and the rat renal mesangial cell model confirmed our findings. We found that the pathogenesis of DKD is linked to hypoxia-mediated lactic acidosis, which leads to fibrosis and mitochondrial abnormalities. The pathogenic characteristics of DKD were significantly reduced when aerobic glycolysis or LDHA expression was inhibited. Further studies will aim to investigate whether local acidosis caused by renal LDHA might be exploited as a therapeutic target in patients with DKD.

Arginase: Biological and Therapeutic Implications in Diabetes Mellitus and Its Complications

Arginase is a ubiquitous enzyme in the urea cycle (UC) that hydrolyzes L-arginine to urea and L-ornithine. Two mammalian arginase isoforms, arginase1 (ARG1) and arginase2 (ARG2), play a vital role in the regulation of β-cell functions, insulin resistance (IR), and vascular complications via modulating L-arginine metabolism, nitric oxide (NO) production, and inflammatory responses as well as oxidative stress. Basic and clinical studies reveal that abnormal alterations of arginase expression and activity are strongly associated with the onset and development of diabetes mellitus (DM) and its complications. As a result, targeting arginase may be a novel and promising approach for DM treatment. An increasing number of arginase inhibitors, including chemical and natural inhibitors, have been developed and shown to protect against the development of DM and its complications. In this review, we discuss the fundamental features of arginase. Next, the regulatory roles and underlying mechanisms of arginase in the pathogenesis and progression of DM and its complications are explored. Furthermore, we review the development and discuss the challenges of arginase inhibitors in treating DM and its related pathologies.

Extrahepatic Manifestations in Alcoholic Liver Disease

Though liver is the most commonly affected organ in patients with chronic and excessive intake of alcohol, no organ is immune to toxic effects of alcohol and patients with alcohol-related liver disease (ALD) can suffer from a wide list of extrahepatic manifestations involving gastrointestinal tract, central and peripheral nervous systems, cardio vascular system, musculo-skeletal system, disruption of nutritional status, endocrinological abnormalities, hematological abnormalities and immune dysfunction. These extrahepatic organ involvements are usually overlooked by hepatologists and physicians who are mostly focused on managing life threatening complications of ALD. As a result, there is delayed diagnosis, delay in the initiation of appropriate treatment and late referral to other specialists. Some of these manifestations are of utmost clinical importance (e.g. delirium tremans and Wernicke's encephalopathy) because an early diagnosis and treatment can lead to full recovery while delayed or no treatment can result in death. On the other hand, several extrahepatic manifestations are of prognostic significance (such as alcoholic cardiomyopathy and malignancies) in which there is an increased risk of morbidity and mortality. Hence, a clear understanding and awareness of the extrahepatic manifestations of ALD is quintessential for proper management of these patients.

Cellular Bioenergetics: Experimental Evidence for Alcohol-induced Adaptations

At-risk alcohol use is associated with multisystemic effects and end-organ injury, and significantly contributes to global health burden. Several alcohol-mediated mechanisms have been identified, with bioenergetic maladaptation gaining credence as an underlying pathophysiological mechanism contributing to cellular injury. This evidence-based review focuses on the current knowledge of alcohol-induced bioenergetic adaptations in metabolically active tissues: liver, cardiac and skeletal muscle, pancreas, and brain. Alcohol metabolism itself significantly interferes with bioenergetic pathways in tissues, particularly the liver. Alcohol decreases states of respiration in the electron transport chain, and activity and expression of respiratory complexes, with a net effect to decrease ATP content. In addition, alcohol dysregulates major metabolic pathways, including glycolysis, the tricarboxylic acid cycle, and fatty acid oxidation. These bioenergetic alterations are influenced by alcohol-mediated changes in mitochondrial morphology, biogenesis, and dynamics. The review highlights similarities and differences in bioenergetic adaptations according to tissue type, pattern of (acute vs. chronic) alcohol use, and energy substrate availability. The compromised bioenergetics synergizes with other critical pathophysiological mechanisms, including increased oxidative stress and accelerates cellular dysfunction, promoting senescence, programmed cell death, and end-organ injury.

Hepatogenous diabetes: Knowledge, evidence, and skepticism

The diabetogenic potential of liver cirrhosis (LC) has been known for a long time, and the name "hepatogenous diabetes" (HD) was coined in 1906 to define the condition. Diabetes mellitus (DM) that develops as a consequence of LC is referred to as HD. In patients with LC, the prevalence rates of HD have been reported to vary from 21% to 57%. The pathophysiological basis of HD seems to involve insulin resistance (IR) and pancreatic β-cell dysfunction. The neurohormonal changes, endotoxemia, and chronic inflammation of LC initially create IR; however, the toxic effects eventually lead to β-cell dysfunction, which marks the transition from impaired glucose tolerance to HD. In addition, a number of factors, including sarcopenia, sarcopenic obesity, gut dysbiosis, and hyperammonemia, have recently been linked to impaired glucose metabolism in LC. DM is associated with complications and poor outcomes in patients with LC, although the individual impact of each type 2 DM and HD is unknown due to a lack of categorization of diabetes in most published research. In fact, there is much skepticism within scientific organizations over the recognition of HD as a separate disease and a consequence of LC. Currently, T2DM and HD are being treated in a similar manner although no standardized guidelines are available. The different pathophysiological basis of HD may have an impact on treatment options. This review article discusses the existence of HD as a distinct entity with high prevalence rates, a strong pathophysiological basis, clinical and therapeutic implications, as well as widespread skepticism and knowledge gaps.

Binge alcohol drinking before pregnancy is closely associated with the development of macrosomia: Korean pregnancy registry cohort

Background

Alcohol drinking during pregnancy has been well-known to cause the detrimental effects on fetal development; however, the adverse effects of pre-pregnancy drinking are largely unknown. We investigate whether alcohol drinking status before pregnancy is associated with the risk for macrosomia, an offspring’s adverse outcome, in a Korean pregnancy registry cohort (n = 4,542) enrolled between 2013 and 2017.

Methods

Binge drinking was defined as consuming ≥5 drinks on one occasion and ≥2 times a week, and a total 2,886 pregnant, included in the final statistical analysis, were divided into 3 groups: never, non-binge, and binge drinking.

Results

The prevalence of macrosomia was higher in binge drinking before pregnancy than those with never or non-binge drinking (7.5% vs. 3.2% or 2.9%, p = 0.002). Multivariable logistic regression analysis demonstrated an independent association between macrosomia and prepregnancy binge drinking after adjusting for other confounders (adjusted odds ratio = 2.29; 95% CI, 1.08–4.86; p = 0.031). The model added binge drinking before pregnancy led to improvement of 10.6% (95% CI, 2.03–19.07; p = 0.0006) in discrimination from traditional risk prediction models.

Conclusion

Together, binge drinking before pregnancy might be an independent risk factor for developing macrosomia. Intensified intervention for drinking alcohol in women who are planning a pregnancy is important and may help prevent macrosomia.

Pathophysiological Consequences of At-Risk Alcohol Use; Implications for Comorbidity Risk in Persons Living With Human Immunodeficiency Virus

At-risk alcohol use is a significant risk factor associated with multisystemic pathophysiological effects leading to multiorgan injury and contributing to 5.3% of all deaths worldwide. The alcohol-mediated cellular and molecular alterations are particularly salient in vulnerable populations, such as people living with HIV (PLWH), diminishing their physiological reserve, and accelerating the aging process. This review presents salient alcohol-associated mechanisms involved in exacerbation of cardiometabolic and neuropathological comorbidities and their implications in the context of HIV disease. The review integrates consideration of environmental factors, such as consumption of a Western diet and its interactions with alcohol-induced metabolic and neurocognitive dyshomeostasis. Major alcohol-mediated mechanisms that contribute to cardiometabolic comorbidity include impaired substrate utilization and storage, endothelial dysfunction, dysregulation of the renin-angiotensin-aldosterone system, and hypertension. Neuroinflammation and loss of neurotrophic support in vulnerable brain regions significantly contribute to alcohol-associated development of neurological deficits and alcohol use disorder risk. Collectively, evidence suggests that at-risk alcohol use exacerbates cardiometabolic and neurocognitive pathologies and accelerates biological aging leading to the development of geriatric comorbidities manifested as frailty in PLWH.

Chronic binge alcohol and ovariectomy-mediated impaired insulin responsiveness in SIV-infected female rhesus macaques

Aging people living with HIV (PLWH), especially postmenopausal women may be at higher risk of comorbidities associated with HIV, antiretroviral therapy (ART), hypogonadism, and at-risk alcohol use. Our studies in simian immunodeficiency virus (SIV)-infected male macaques demonstrated that chronic binge alcohol (CBA) reduced acute insulin response to glucose (AIRG), and at-risk alcohol use decreased HOMA-β in PLWH. The objective of this study was to examine the impact of ovariectomy (OVX) on glucose-insulin dynamics and integrity of pancreatic endocrine function in CBA/SIV-infected female macaques. Female macaques were administered CBA (12-15 g/kg/wk) or isovolumetric water (VEH) intragastrically. Three months after initiation of CBA/VEH administration, all macaques were infected with SIVmac251, and initiated on antiretroviral therapy (ART) 2.5 mo postinfection. After 1 mo of ART, macaques were randomized to OVX or sham surgeries (n = 7 or 8/group), and euthanized 8 mo post-OVX (study endpoint). Frequently sampled intravenous glucose tolerance tests (FSIVGTT) were performed at selected time points. Pancreatic gene expression and islet morphology were determined at study endpoint. There was a main effect of CBA to decrease AIRG at Pre-SIV and study endpoint. There were no statistically significant OVX effects on AIRG (P = 0.06). CBA and OVX decreased the expression of pancreatic markers of insulin docking and release. OVX increased endoplasmic stress markers. CBA but not OVX impaired glucose-insulin expression dynamics in SIV-infected female macaques. Both CBA and OVX altered integrity of pancreatic endocrine function. These findings suggest increased vulnerability of PLWH to overt metabolic dysfunction that may be exacerbated by alcohol use and ovarian hormone loss.

Alcohol and Metabolic-associated Fatty Liver Disease

The diagnosis of metabolic-associated fatty liver disease is based on the detection of liver steatosis together with the presence of metabolic dysfunction. According to this new definition, the diagnosis of metabolic-associated fatty liver disease is independent of the amount of alcohol consumed. Actually, alcohol and its metabolites have various effects on metabolic-associated abnormalities during the process of alcohol metabolism. Studies have shown improved metabolic function in light to moderate alcohol drinkers. There are several studies focusing on the role of light to moderate alcohol intake on metabolic dysfunction. However, the results from studies are diverse, and the conclusions are often controversial. This review systematically discusses the effects of alcohol consumption, focusing on light to moderate alcohol consumption, obesity, lipid and glucose metabolism, and blood pressure.

Hepatogenous Diabetes: A Primer

As liver is one of the primary organs involved in glucose homeostasis, it is not surprising that patients with liver dysfunction in chronic liver disease usually develop impaired glucose tolerance and subsequently overt diabetes later in their natural course. Diabetes that develops after the onset of cirrhosis of liver is usually referred to as hepatogenous diabetes (HD). It is an underrecognized and a hallmark endocrinological event in chronic liver disease. HD is associated with a higher risk of developing hepatic decompensations, such as ascites, variceal bleeding, hepatic encephalopathy, renal dysfunction, refractory ascites, and hepatocellular carcinoma along with reduced survival rates than normoglycemic patients with cirrhosis of liver. It is quite different from type 2 diabetes mellitus with the absence of classical risk factors, dissimilar laboratory profiles, and decreased incidence of microvascular complications. Furthermore, the management of patients with HD is challenging because of altered pharmacokinetics of most antidiabetic drugs and increased risk of hypoglycemia and other adverse effects. Hence, a clear understanding of the epidemiology, pathophysiology, clinical implications, laboratory diagnosis, and management of HD is essential for both hepatologists as well as endocrinologists, which is narrated briefly in this review.

Impact of alcohol use disorder on stroke risk in geriatric patients with prediabetes: A nationwide analysis

BACKGROUND

With rising trends of prediabetes in the geriatric population, we aim to assess the impact of alcohol use disorder (AUD) on the outcomes of patients with prediabetes.

METHODS

Hospitalisations amongst the patients (≥65 years) with prediabetes were identified with a diagnosis of AUD and in-hospital stroke using the National Inpatient Sample database (2007-2014). We compared demographics, comorbidities, all-cause mortality, stroke rate and resource utilisation in the elderly prediabetes patients with vs without AUD. Primary outcomes of interest were all-cause mortality and stroke rate, whereas secondary outcomes were the length of stay (days), disposition and resource utilisation in the AUD cohort as compared to the non-AUD cohort.

RESULTS

We had a total of 1.7 million hospitalisations amongst elderly patients with prediabetes, 2.8% (n = 47 962) had AUD. The AUD cohort was more often younger (71 vs 77 years), male (74.1% vs 43.5%) and nonelectively (84.5% vs 78.3%) admitted than non-AUD cohort. The AUD cohort more often consisted of African Americans (9.0% vs 6.6%) and Hispanics (5.3% vs 5.1%) than non-AUD cohort. The AUD cohort showed higher rates of smoking, drug abuse, chronic obstructive pulmonary disease, coagulopathy, peripheral vascular disease and fluid-electrolyte disorders whereas a lower rate of cardiovascular risk factors than non-AUD cohort. All-cause mortality (4.4% vs 3.9%) and stroke (5.5% vs 4.8%, aOR 1.33, 95% CI 1.28-1.39) were significantly higher in the AUD cohort with prolonged stay, higher charges and frequent transfers than non-AUD cohort.

CONCLUSION

AUD in the elderly prediabetes patients increases the stroke risk by up to 33% which can adversely influence the survival rate and healthcare infrastructure.

A Review of Current Trends with Type 2 Diabetes Epidemiology, Aetiology, Pathogenesis, Treatments and Future Perspectives

Type 2 diabetes (T2D), which has currently become a global pandemic, is a metabolic disease largely characterised by impaired insulin secretion and action. Significant progress has been made in understanding T2D aetiology and pathogenesis, which is discussed in this review. Extrapancreatic pathology is also summarised, which demonstrates the highly multifactorial nature of T2D. Glucagon-like peptide (GLP)-1 is an incretin hormone responsible for augmenting insulin secretion from pancreatic beta-cells during the postprandial period. Given that native GLP-1 has a very short half-life, GLP-1 mimetics with a much longer half-life have been developed, which are currently an effective treatment option for T2D by enhancing insulin secretion in patients. Interestingly, there is continual emerging evidence that these therapies alleviate some of the post-diagnosis complications of T2D. Additionally, these therapies have been shown to induce weight loss in patients, suggesting they could be an alternative to bariatric surgery, a procedure associated with numerous complications. Current GLP-1-based therapies all act as orthosteric agonists for the GLP-1 receptor (GLP-1R). Interestingly, it has emerged that GLP-1R also has allosteric binding sites and agonists have been developed for these sites to test their therapeutic potential. Recent studies have also demonstrated the potential of bi- and tri-agonists, which target multiple hormonal receptors including GLP-1R, to more effectively treat T2D. Improved understanding of T2D aetiology/pathogenesis, coupled with the further elucidation of both GLP-1 activity/targets and GLP-1R mechanisms of activation via different agonists, will likely provide better insight into the therapeutic potential of GLP-1-based therapies to treat T2D.

Lentinan protects against pancreatic β-cell failure in chronic ethanol consumption-induced diabetic mice via enhancing β-cell antioxidant capacity

Chronic ethanol consumption is a well-established independent risk factor for type 2 diabetes mellitus (T2DM). Recently, increasing studies have confirmed that excessive heavy ethanol exerts direct harmful effect on pancreatic β-cell mass and function, which may be a mechanism of pancreatic β-cell failure in T2DM. In this study, we evaluated the effect of Lentinan (LNT), an active ingredient purified from the bodies of Lentinus edodes, on pancreatic β-cell apoptosis and dysfunction caused by ethanol and the possible mechanisms implicated. Functional studies reveal that LNT attenuates chronic ethanol consumption-induced impaired glucose metabolism in vivo. In addition, LNT ameliorates chronic ethanol consumption-induced β-cell dysfunction, which is characterized by reduced insulin synthesis, defected insulin secretion and increased cell apoptosis. Furthermore, mechanistic assays suggest that LNT enhances β-cell antioxidant capacity and ameliorates ethanol-induced oxidative stress by activating Nrf-2 antioxidant pathway. Our results demonstrated that LNT prevents ethanol-induced pancreatic β-cell dysfunction and apoptosis, and therefore may be a potential pharmacological agent for preventing pancreatic β-cell failure associated with T2DM and stress-induced diabetes.

The oxidative reactivity of three manganese(III) porphyrin complexes with hydrogen peroxide and nitrite toward catalytic nitration of protein tyrosine

Understanding the toxicological properties of MnIII-porphyrins (MnTPPS, MnTMPyP, or MnTBAP) can provide important biochemical rationales in developing them as the therapeutic drugs against protein tyrosine nitration-induced inflammation diseases. Here, we present a comprehensive understanding of the pH-dependent redox behaviors of these MnIII-porphyrins and their structural effects on catalyzing bovine serum albumin (BSA) nitration in the presence of H2O2 and NO2-. It was found that both MnTPPS and MnTBAP stand out in catalyzing BSA nitration at physiologically close condition (pH 8), yet they are less effective at pH 6 and 10. MnTMPyP was shown to have no ability to catalyze BSA nitration under all tested pHs (pH 6, 8, and 10). The kinetics and active intermediate determination through electrochemistry method revealed that both the pH-dependent redox behavior of the central metal cation and the antioxidant capability of porphin derivative contribute to the catalytic activities of three MnIII-porphyrins in BSA nitration in the presence of H2O2/NO2-. These comprehensive studies on the oxidative reactivity of MnIII-porphyrins toward BSA nitration may provide new clues for searching the manganese-based therapeutic drugs against the inflammation-related diseases.

Human Nitric Oxide Synthase-Its Functions, Polymorphisms, and Inhibitors in the Context of Inflammation, Diabetes and Cardiovascular Diseases

In various diseases, there is an increased production of the free radicals needed to carry out certain physiological processes but their excessive amounts can cause oxidative stress and cell damage. Enzymes play a major role in the transformations associated with free radicals. One of them is nitric oxide synthase (NOS), which catalyzes the formation of nitric oxide (NO). This enzyme exists in three forms (NOS1, NOS2, NOS3), each encoded by a different gene. The following work presents the most important information on the NOS isoforms and their role in the human body, including NO synthesis in various tissues and cells, intercellular signaling and activities supporting the immune system and regulating blood vessel functions. The role of NOS in pathological conditions such as obesity, diabetes and heart disease is considered. Attention is also paid to the influence of the polymorphisms of these genes, encoding particular isoforms, on the development of these pathologies and the role of NOS inhibitors in the treatment of patients.

Resveratrol attenuates excessive ethanol exposure-induced β-cell senescence in rats: A critical role for the NAD+/SIRT1-p38MAPK/p16 pathway

Resveratrol has been found to improve ethanol-induced diabetes. Although pancreatic β-cell senescence-induced β-cell mass loss plays a critical role in the progression of diabetes, the exact mechanism by which resveratrol improves ethanol-triggered β-cell senescence and its role in ethanol-induced diabetes remains unknown. Male Sprague-Dawley rats were fed either control or ethanol liquid diets containing 2.4 g/kg·bw ethanol with or without 100 mg/kg·bw resveratrol for 22 weeks. Resveratrol decreased the ethanol-induced augmentation in senescence-associated β-galactosidase (SA-β-gal)-positive area and attenuated reduction in β-cell mass, which were based on elevated levels of SIRT1 and proliferation marker Ki67 and reduced levels of senescence-associated markers (p-p38MAPK and p16^INK4a). Similarly, resveratrol rescued the reduction in NAD⁺/NADH ratio and SIRT1 and inhibited the upregulation of p-p38MAPK and p16^INK4a in ethanol-treated INS-1 cells. Furthermore, supplementation with NAD⁺ inducer nicotinamide mononucleotide, SIRT1 activator SRT1720 or p38MAPK inhibitor SB203580 effectively reversed ethanol-induced β-cell senescence, while supplementation with SIRT1 inhibitor Ex527 or NAD⁺ inhibitor FK866 abrogated resveratrol-mediated antisenescence effects in INS-1 cells. Together, our results indicate that resveratrol improves ethanol-triggered β-cell senescence and consequently recovers β-cell mass loss by inhibiting p38MAPK/p16 pathway through an NAD⁺/SIRT1 dependent pathway.

Clinical implications, diagnosis, and management of diabetes in patients with chronic liver diseases

Diabetes mellitus (DM) negatively affects the development and progression of chronic liver diseases (CLD) of various etiologies. Concurrent DM and CLD are also associated with worse clinical outcomes with respect to mortality, the occurrence of hepatic decompensation, and the development of hepatocellular carcinoma (HCC). Unfortunately, early diagnosis and optimal treatment of DM can be challenging, due to the lack of established clinical guidelines as well as the medical complexity of this patient population. We conducted an exploratory review of relevant literature to provide an up-to-date review for internists and hepatologists caring for this patient population. We reviewed the epidemiological and pathophysiological associations between DM and CLD, the impact of insulin resistance on the progression and manifestations of CLD, the pathogenesis of hepatogenic diabetes, as well as the practical challenges in diagnosis and monitoring of DM in this patient population. We also reviewed the latest clinical evidence on various pharmacological antihyperglycemic therapies with an emphasis on liver disease-related clinical outcomes. Finally, we proposed an algorithm for managing DM in patients with CLD and discussed the clinical and research questions that remain to be addressed.

Associations of alcohol consumption and physical activity with lean type 2 diabetes mellitus among Korean adults: A prospective cohort study

Data on the association between alcohol consumption and the risk of type 2 diabetes mellitus (T2DM) have accumulated, but little has been reported about this association in terms of lean T2DM. The present study analyzed 10-year longitudinal data to investigate the association between alcohol consumption and T2DM risk among lean individuals. This prospective study included 2,366 male and female Koreans aged 40–69 years who were free of DM and had a body mass index (BMI) <23 kg/m² during the baseline period between 2001 and 2012. Information on alcohol consumption, BMI, and incident cases of T2DM were identified by interviews and health examinations. To analyze the association between alcohol consumption and T2DM risk, Cox proportional hazard regression analysis was used. Alcohol drinkers consuming at least 16 g/day of alcohol (2 units/day) who maintained a BMI <23 kg/m² over 10 years had a significantly higher T2DM risk even after controlling for BMI and potential risk factors. Compared with lifetime abstainers, multivariate hazard ratios (HR) [95% confidence interval] of T2DM were 1.74 [1.02, 2.95] for 16–30 g/day, 2.09 [1.16, 3.77] for 31–60 g/day, and 1.94 [1.07, 3.51] for >60g/day among alcohol drinkers. No protective effect of moderate alcohol consumption <16 g/day on T2DM risk was observed. Age, parental history of DM, and physical inactivity were also significant risk factors for lean T2DM. Alcohol consumption of at least 2 units/day increased T2DM risk among lean individuals. Abstaining from alcohol and physical activity may be beneficial for the prevention of lean T2DM.

Alcohol consumption before pregnancy causes detrimental fetal development and maternal metabolic disorders

Alcohol consumption before or during pregnancy poses serious health risks to the fetus; however, the underlying mechanisms involved remain obscure. Here, we investigated whether ethanol consumption before pregnancy affects maternal or fetal health and whether pharmacological inhibition of CYP2E1, a major ethanol oxidation enzyme, by 4-methylpyrazole (4-MP) has therapeutic effects. We found that ethanol consumption (5%) 2 weeks before pregnancy resulted in a decrease in the number of viable fetuses and abnormal fetal development, and these effects were accompanied by impaired maternal glucose homeostasis and hepatic steatosis during pregnancy. Neonates of ethanol-fed mice had postnatal macrosomia and significantly decreased growth rates during the lactation period. However, treatment with 4-MP, a CYP2E1 inhibitor, markedly ameliorated the reduction in insulin action and glucose disposal responsiveness in the livers of ethanol-fed mice. Blockage of CYP2E1 significantly reduced the alteration in hepatic lipid deposition, fatty acid oxidation, mitochondrial energy status, and macrophage infiltration observed in ethanol-fed mice. Finally, there was a positive correlation between postnatal macrosomia or growth retardation and increased inflammatory responses. Collectively, our study suggests that even moderate ethanol intake may be detrimental to fetal development and may cause growth retardation through maternal metabolic disorders.

Recent Advances in Understanding the Complexity of Alcohol-Induced Pancreatic Dysfunction and Pancreatitis Development

Chronic excessive alcohol use is a well-recognized risk factor for pancreatic dysfunction and pancreatitis development. Evidence from in vivo and in vitro studies indicates that the detrimental effects of alcohol on the pancreas are from the direct toxic effects of metabolites and byproducts of ethanol metabolism such as reactive oxygen species. Pancreatic dysfunction and pancreatitis development are now increasingly thought to be multifactorial conditions, where alcohol, genetics, lifestyle, and infectious agents may determine the initiation and course of the disease. In this review, we first highlight the role of nonoxidative ethanol metabolism in the generation and accumulation of fatty acid ethyl esters (FAEEs) that cause multi-organellar dysfunction in the pancreas which ultimately leads to pancreatitis development. Further, we discuss how alcohol-mediated altered autophagy leads to the development of pancreatitis. We also provide insights into how alcohol interactions with other co-morbidities such as smoking or viral infections may negatively affect exocrine and endocrine pancreatic function. Finally, we present potential strategies to ameliorate organellar dysfunction which could attenuate pancreatic dysfunction and pancreatitis severity.

The Pathophysiology of Type 2 Diabetes Mellitus in Non-obese Individuals: An Overview of the Current Understanding

The pandemic of type 2 diabetes mellitus (T2DM) has been largely attributed to the increasing prevalence of worldwide obesity at a geometric rate. However, the number of non-obese patients with T2DM is also on the rise, and it is as high as 60-80% in some Asian countries. These non-obese individuals have certain peculiarities and have a higher mortality rate compared with obese individuals. The pathophysiology of T2DM in non-obese individuals remains poorly understood, and this has an impact on defining its management. This review discusses the current understanding of the pathophysiology of T2DM in non-obese individuals. The definition of T2DM in non-obese individuals remains controversial because of the limited clinical measurements, and the current definition of obesity using body mass index (BMI) is not very helpful as these individuals have BMIs of <25K g/m3, which is considered normal. Many authors have argued that the so-called non-obese people are actually metabolically obese; however, in terms of the measurements clinically available, they are non-obese. The simplistic understanding of the mechanism of the pathophysiology sees it in terms of the balance between insulin secretion and insulin resistance. The pathogenesis of insulin resistance in a lean patient has been proven to be the same as what is seen in an obese individual, but most studies confirm more severe functional insulin secretory defects in lean individuals compared to the obese phenotype. The mechanism underlying this form of T2DM is still poorly defined, and more research is required to understand the mechanism of sarcopenic obesity, which some studies have revealed.

Influence of Chronic Ethanol Consumption on Apoptosis and Autophagy Following Transient Focal Cerebral Ischemia in Male Mice

Stroke remains one of the leading causes of permanent disability and death worldwide. Apoptosis and autophagy are two key elements involved in ischemic brain damage. Ethanol is a commonly used and abused chemical substance that affects the prognosis of ischemic stroke. We determined the influence of chronic ethanol consumption on apoptosis and autophagy following transient focal cerebral ischemia. Male C57BL/6 J mice were randomly divided into three groups and gavage fed with 0.7 and 2.8 g/kg/day ethanol or volume-matched water daily for 8 weeks. DNA fragmentation, TUNEL-positive neurons, cleaved caspase-3-positive neurons, translocation of mitochondrial cytochrome C and apoptosis inducing factor (AIF), LC3B-positive neurons, and expression of LC3B, Beclin-1 and Bcl-2 in peri-infarct cortex were evaluated at 24 hours of reperfusion after a 90-minute unilateral middle cerebral artery occlusion (MCAO). Cerebral ischemia/reperfusion (I/R) injury was significantly improved in the 0.7 g/kg/d ethanol group but worsened in the 2.8 g/kg/d ethanol group. DNA fragmentation was significantly increased at 24 hours of reperfusion in all groups. However, the magnitude of the increase was significantly less in the 0.7 g/kg/d ethanol group. In addition, both cleaved caspase-3-positive neurons and TUNEL-positive neurons were significantly less in 0.7 g/kg/d ethanol group. Furthermore, translocation of mitochondrial cytochrome C and AIF was significantly alleviated in the 0.7 g/kg/d ethanol group. On the other hand, baseline expression of LC3B was significantly reduced in the 2.8 g/kg/d ethanol group. Post-ischemic expression of LC3B and LC3B-positive neurons were significantly attenuated in both 0.7 and 2.8 g/kg/d ethanol groups. Moreover, although post-ischemic expression of Beclin-1 was not altered in the ethanol groups, post-ischemic expression of Bcl-2 was significantly greater in both 0.7 and 2.8 g/kg/d ethanol groups. Our findings suggest that light ethanol consumption may protect against cerebral I/R injury by suppressing post-ischemic apoptosis, whereas heavy ethanol consumption may exacerbate cerebral I/R injury by suppressing autophagy.

Alcohol ingestion induces pancreatic islet dysfunction and apoptosis via mediation of FGF21 resistance

Background

Disruption of β-cell insulin secretion and viability caused by excessive ethanol consumption increases type 2 diabetes mellitus (T2DM) pathogenesis risk. Fibroblast growth factor 21 (FGF21) plays a significant role in regulating lipid and glucose homeostasis. Recently, FGF21, best known for its role in lipid and glucose homeostasis regulation, and its obligate co-receptor β-klotho have been shown to inhibit ethanol ingestion and metabolism. It remains unclear whether heavy ethanol intake modulates islet FGF21 expression and function. This study investigated the relationship between ethanol exposure, FGF21, and islet function in vivo/ex vivo islet and in vitro cell models.

Methods

Mice were gavaged with 3.5 g/kg ethanol or saline for 1–3 weeks (long-term exposure). Human MIN6 cells and isolated islets were cultured and treated with 80 mM ethanol for 24 h (short-term exposure) to mimic excessive ethanol consumption. We applied the oral glucose tolerance test (OGTT), blood glucometry, enzyme-linked immunosorbent assay (ELISAs) for insulin and FGF21, glucose stimulated insulin secretion (GSIS) testing, reverse-transcription (RT)-polymerase chain reaction (PCR), and western blot experiments.

Results

Long-term ethanol treatment induced FGF21 resistance in mouse pancreatic islets. Moreover, ethanol exposure damaged insulin secretory ability and glucose homeostasis. In vitro and ex vivo experiments showed that short-term ethanol treatment upregulated the expression of FGF21 signaling pathway-related genes and proteins, without affecting β-cell survival or function.

Conclusions

Long-term ethanol consumption induces FGF21 resistance-mediated pancreatic β-cell dysfunction, and thus diabetes pathogenesis risk.

Resveratrol protects against ethanol-induced impairment of insulin secretion in INS-1 cells through SIRT1-UCP2 axis

SIRT1 has been proposed to enhance insulin secretion in β-cell through repressing the expression of uncoupling protein2 (UCP2), but whether ethanol-induced β-cell dysfunction is mediated by the disrupted SIRT1-UCP2 axis remains unknown. This study was conducted to explore the underlying mechanisms by which ethanol resulted in β-cell dysfunction and the potential protective effects of resveratrol in this process. INS-1 cells (rat pancreatic β-cell line) were cultured with ethanol in the presence or absence of resveratrol (2.5, 12.5 μmol/L). The results showed that ethanol exposure reduced glucose-stimulated insulin secretion, ATP production and SIRT1 expression but increased UCP2 expression, while supplementation with resveratrol restored the function of INS-1 cell by upregulating SIRT1 and inhibiting UCP2. Moreover, the critical role of SIRT1-UCP2 axis was further supported by the results that SIRT1 activator SRT1720 reversed ethanol-induced impairment of glucose-stimulated insulin secretion by decreasing UCP2, while SIRT1 inhibitor Ex527 abolished the beneficial effects of resveratrol. Meanwhile, NAD⁺ booster nicotinamide mononucleotide also counteracted the deleterious effects of ethanol by increasing SIRT1, suggesting the regulation of SIRT1-UCP2 axis may be associated with cellular NAD⁺/NADH ratio. In conclusion, our observations imply that ethanol induces impaired insulin secretion from INS-1 cell through disrupting SIRT1-UCP2 axis, while resveratrol may reverse this process by augmenting SIRT1 and inhibiting UCP2.

Role of Nitric Oxide in Insulin Secretion and Glucose Metabolism

Nitric oxide (NO) contributes to carbohydrate metabolism and decreased NO bioavailability is involved in the development of type 2 diabetes mellitus (T2DM). NO donors may improve insulin signaling and glucose homeostasis in T2DM and insulin resistance (IR), suggesting the potential clinical importance of NO-based interventions. In this review, site-specific roles of the NO synthase (NOS)-NO pathway in carbohydrate metabolism are discussed. In addition, the metabolic effects of physiological low levels of NO produced by constitutive NOS (cNOS) versus pathological high levels of NO produced by inducible NOS (iNOS) in pancreatic β-cells, adipocytes, hepatocytes, and skeletal muscle cells are summarized. A better understanding of the NOS-NO system in the regulation of glucose homeostasis can hopefully facilitate the development of new treatments for T2DM.

Effect of imidazoline-1 receptor agonists on renal dysfunction in rats associated with chronic, sequential fructose and ethanol administration

Insulin resistance and chronic alcoholism are risk factors for renal dysfunction. This study investigated the therapeutic effects of two imidazoline-1 receptor (I1R) agonists on renal dysfunction in rats after chronic, sequential fructose and ethanol administration. Daily drinking water was supplemented with fructose (10%, w/v) for 12 weeks and then with ethanol (20%, v/v) for another 8 weeks. Rats were treated with rilmenidine and clonidine in the last two weeks of the study. Blood glucose and serum insulin (sIns) levels, lipid profiles, kidney function and renal histopathology were evaluated at the end of the experiment. Additionally, renal gene expression of nischarin, phosphatidylcholine-specific phospholipase C (PC-PLC) and prostaglandin E2 (PGE2) were measured. Renal levels of superoxide dismutase (SOD), malondialdehyde (MDA), myeloperoxidase (MPO), inducible nitric oxide synthase (iNOS) and total NO (tNO) were detected, and we determined the relative renal gene expression levels of alpha smooth muscle actin (α-SMA), hydroxyproline, interleukin 10 (IL-10), tumour necrosis factor alpha (TNF-α) and caspase-3. The results showed significant deterioration of blood glucose, sIns, lipid profiles, kidney function and renal histopathology in fructose/ethanol-fed rats. Additionally, markers of inflammation, fibrosis, apoptosis and oxidative stress were upregulated. The administration of rilmenidine or clonidine significantly improved blood glucose and sIns levels and reduced renal dysfunction. Our work showed that chronic, sequential fructose and ethanol administration induced fasting hyperglycaemia and renal impairment, and these effects were ameliorated by I1R agonists.

Chronic heavy alcohol consumption influences the association between genetic variants of GCK or INSR and the development of diabetes in men: A 12-year follow-up study

Chronic heavy alcohol consumption is a risk factor for diabetes, which is characterized by impaired β-cell function and insulin resistance. We aimed to determine whether the longitudinal associations between genetic variants of glucokinase (GCK) and insulin receptor (INSR) and the risk of developing diabetes were influenced by chronic heavy alcohol consumption. Data were obtained from the Korean Genome and Epidemiology Study. To identify candidate variants, 1,520 subjects (726 non-drinkers and 794 heavy drinkers) were included in the baseline cross-sectional study. After excluding patients with diabetes at baseline and those with insufficient data on diabetes incidence, prospective analyses were conducted in 773 subjects (353 non-drinkers and 420 heavy drinkers). In the baseline cross-sectional study, one SNP (rs758989) in GCK and four SNPs (rs7245757, rs1035942, rs1035940, and rs2042901) in INSR were selected as candidate SNPs that interact with alcohol to affect prediabetes and diabetes. We identified that these GCK and INSR polymorphisms are affected by chronic heavy alcohol consumption and have an effect on the incidence of diabetes. The incidence of diabetes was increased in chronic heavy alcohol drinkers carrying the C allele of GCK compared with never-drinkers with the C allele (HR, 2.15; 95% CI 1.30-3.57), and was increased in chronic heavy alcohol drinkers who were not carrying the INSR haplotype (-/-) compared with never-drinkers carrying the AACT haplotype (HR, 1.98; 95% CI 1.24-3.18). Moreover, we observed that the aggravating effects on the late insulin secretion (I/G120 and I/G AUC 60-120) in individuals who were chronic heavy drinkers with C allele of GCK. In the INSR haplotype, chronic heavy drinkers not carrying AACT were associated with lower disposition index. These results potentially suggest that chronic heavy alcohol consumption induce β-cell dysfunction partially mediated by decreased GCK expression or decline of insulin sensitivity via inhibition of INSR, thereby contributing to the development of diabetes.

Inhibition of Ghrelin Activity by Receptor Antagonist [d-Lys-3] GHRP-6 Attenuates Alcohol-Induced Hepatic Steatosis by Regulating Hepatic Lipid Metabolism

Alcoholic steatosis, characterized by an accumulation of triglycerides in hepatocytes, is one of the earliest pathological changes in the progression of alcoholic liver disease. In our previous study, we showed that alcohol-induced increase in serum ghrelin levels impair insulin secretion from pancreatic β-cells. The consequent reduction in the circulating insulin levels promote adipose-derived fatty acid mobilization to ultimately contribute to hepatic steatosis. In this study, we determined whether inhibition of ghrelin activity in chronic alcohol-fed rats could improve hepatic lipid homeostasis at the pancreas-adipose-liver axis. Adult Wistar rats were fed Lieber-DeCarli control or an ethanol liquid diet for 7 weeks. At 6 weeks, a subset of rats in each group were injected with either saline or ghrelin receptor antagonist, [d-Lys-3] GHRP-6 (DLys; 9 mg/kg body weight) for 5 days and all rats were sacrificed 2 days later. DLys treatment of ethanol rats improved pancreatic insulin secretion, normalized serum insulin levels, and the adipose lipid metabolism, as evidenced by the decreased serum free fatty acids (FFA). DLys treatment of ethanol rats also significantly decreased the circulating FFA uptake, de novo hepatic fatty acid synthesis ultimately attenuating alcoholic steatosis. To summarize, inhibition of ghrelin activity reduced alcoholic steatosis by improving insulin secretion, normalizing serum insulin levels, inhibiting adipose lipolysis, and preventing fatty acid uptake and synthesis in the liver. Our studies provided new insights on the important role of ghrelin in modulating the pancreas-adipose-liver, and promoting adipocyte lipolysis and hepatic steatosis. The findings offer a therapeutic approach of not only preventing alcoholic liver injury but also treating it.

Autoantibody-positivity in lean type II diabetes patients was associated with elevated Th17-like CD4+CXCR5+ T cell responses

The pathophysiology of type II diabetes (T2D) in patients with normal body-mass index (BMI) remains unclear. In this study, we investigated the circulating CD4⁺CXCR5⁺ T cells in lean T2D patients. Compared with age-, gender-, and BMI-matched healthy controls, the lean T2D patients presented similar frequency and number of CD4⁺CXCR5⁺ T cells; however, the composition of CD4⁺CXCR5⁺ T subsets was altered. The CD4⁺CXCR5⁺ T cells in lean T2D patients were enriched with a Th17-like subset, characterized by an increase in the frequency of IL-17-secreting cells, and an increase in the frequency of CCR6⁺ cells. Compared to CCR6^- CD4⁺CXCR5⁺ T cells, CCR6⁺ CD4⁺CXCR5⁺ T cells secreted significantly higher IL-17. Neither the frequency of IL-17-secreting CD4⁺CXCR5⁺ T cells, nor the frequency of CCR6⁺ CD4⁺CXCR5⁺ T cells, was associated with the BMI of the T2D patients. Interestingly, 10 out of 30 lean T2D patients in our cohort presented islet-reactive autoantibodies. Compared to the autoantibody-negative T2D patients, the autoantibody-positive T2D patients had significantly higher levels of IL-17-secreting CD4⁺CXCR5⁺ T cells and CCR6⁺ CD4⁺CXCR5⁺ T cells. In addition, compared to the CCR6^- CD4⁺CXCR5⁺ T cells, the CCR6⁺ CD4⁺CXCR5⁺ T cells were more effective at promoting Ig secretion from autologous B cells. Together, this study demonstrated that an upregulation of Th17-like CD4⁺CXCR5⁺ T cells was present in lean T2D patients and was associated with autoantibody positivity.

Chronic alcohol exposure alters circulating insulin and ghrelin levels: role of ghrelin in hepatic steatosis

Fatty liver is the earliest response of the liver to excessive ethanol consumption. Central in the development of alcoholic steatosis is increased mobilization of nonesterified free fatty acids (NEFAs) to the liver from the adipose tissue. In this study, we hypothesized that ethanol-induced increase in ghrelin by impairing insulin secretion, could be responsible for the altered lipid metabolism observed in adipose and liver tissue. Male Wistar rats were fed for 5-8 wk with control or ethanol Lieber-DeCarli diet, followed by biochemical analyses in serum and liver tissues. In addition, in vitro studies were conducted on pancreatic islets isolated from experimental rats. We found that ethanol increased serum ghrelin and decreased serum insulin levels in both fed and fasting conditions. These results were corroborated by our observations of a significant accumulation of insulin in pancreatic islets of ethanol-fed rats, indicating that its secretion was impaired. Furthermore, ethanol-induced reduction in circulating insulin was associated with lower adipose weight and increased NEFA levels observed in these rats. Additionally, we found that increased concentration of serum ghrelin was due to increased synthesis and maturation in the stomach of the ethanol-fed rats. We also report that in addition to its effect on the pancreas, ghrelin can also directly act on hepatocytes via the ghrelin receptors and promote fat accumulation. In conclusion, alcohol-induced elevation of circulating ghrelin levels impairs insulin secretion. Consequently, reduced circulating insulin levels likely contribute to increased free fatty acid mobilization from adipose tissue to liver, thereby contributing to hepatic steatosis. NEW & NOTEWORTHY Our studies are the first to report that ethanol-induced increases in ghrelin contribute to impaired insulin secretion, which results in the altered lipid metabolism observed in adipose and liver tissue in the setting of alcoholic fatty liver disease.

Redox Regulation of Hexokinases

SIGNIFICANCE

Hexokinases are key enzymes that are responsible for the first reaction of glycolysis, but they also moonlight other cellular processes, including mitochondrial redox signaling regulation. Modulation of hexokinase activity and spatiotemporal location by reactive oxygen and nitrogen species as well as other gasotransmitters serves as the basis for a unique, underexplored method of tight and flexible regulation of these fundamental enzymes. Recent Advances: Redox modifications of thiols serve as a molecular code that enables the precise and complex regulation of hexokinases. Redox regulation of hexokinases is also used by multiple parasites to cause widespread and severe diseases, including malaria, Chagas disease, and sleeping sickness. Redox-active molecules affect each other, and the moonlighting activity of hexokinases provides another feedback loop that affects the cellular redox status and is hijacked in malignantly transformed cells.

CRITICAL ISSUES

Several compounds affect the redox status of hexokinases in vivo. These include the dehydroascorbic acid (oxidized form of vitamin C), pyrrolidinium porrolidine-1-carbodithioate (contraceptive), peroxynitrite (product of ethanol metabolism), alloxan (a glucose analog), and isobenzothiazolinone ebselen. However, very limited information is available regarding which amino acid residues in hexokinases are affected by redox signaling. Except in cases of monogenic diabetes, direct evidence is absent for disease phenotypes that are associated with variations within motifs that are susceptible to redox signaling.

FUTURE DIRECTIONS

Further studies should address the propensity of hexokinases and their disease-associated variants to participate in redox regulation. Robust and straightforward proteomic methods are needed to understand the context and consequences of hexokinase-mediated redox regulation in health and disease.

Age-Characteristic Changes of Glucose Metabolism, Pancreatic Morphology and Function in Male Offspring Rats Induced by Prenatal Ethanol Exposure

Intrauterine growth restricted offspring suffer from abnormal glucose homeostasis and β cell dysfunction. In this study, we observed the dynamic changes of glucose metabolic phenotype, pancreatic morphology, and insulin synthesis in prenatal ethanol exposure (PEE) male offspring rats, and to explore the potential intrauterine programming mechanism of the glucocorticoid-insulin-like growth factor 1 (GC-IGF1) axis. Ethanol (4 g/kg·d) was administered through oral gavage during gestational day (GD) 9-20. Serum glucose and insulin levels, pancreatic β cell mass, and expression of glucocorticoid receptor (GR), IGF1 and insulin were determined on GD20, postnatal week (PW) 6, PW12 with/without chronic stress (CS), and PW24, respectively. Both intraperitoneal glucose and insulin tolerance tests were conducted at PW12 and PW24. Results showed that the serum glucose and insulin levels as well as pancreatic β cell mass were reduced on GD20 in PEE males compared with the controls, while pancreatic GR expression was enhanced but IGF1 and INS1/2 expression were suppressed. After birth, compared with the controls, β cell mass in the PEE males was initially decreased at PW6 and gradually recovered from PW12 to PW24, which was accompanied by increased serum glucose/insulin levels and insulin resistance index (IRI) at PW6 and decreased serum glucose contents at PW12, as well as unchanged serum glucose/insulin concentrations at PW24. In addition, both improved glucose tolerance and impaired insulin sensitivity of the PEE males at PW12 were inversed at PW24. Moreover, at PW6 and PW12, pancreatic GR expression in the PEE group was decreased, while IGF1 expression was reversely increased, resulting in a compensatory increase of insulin expression. Moreover, CS induced pancreatic GR activation and inhibited IGF1 expression, resulting in impaired insulin biosynthesis. Conclusively, the above changes were associated with age and the intrauterine programming alteration of GC-IGF1 axis may be involved in prenatal and postnatal pancreatic dysplasia and impaired insulin biosynthesis in PEE male offspring.

Activating transcription factor 3 in immune response and metabolic regulation

Activating transcription factor 3 (ATF3) is a member of the ATF/cAMP-response element binding protein (CREB) family of transcription factors. In response to stress stimuli, ATF3 forms dimers to activate or repress gene expression. Further, ATF3 modulates the immune response, atherogenesis, cell cycle, apoptosis, and glucose homeostasis. Recent studies have shown that ATF3 may also be involved in pathogenesis of other diseases. However, more studies are needed to determine the role of ATF3 in metabolic regulation.

Lean diabetes in middle-aged adults: A joint analysis of the German DIVE and DPV registries

AIMS

To assess differences in demographics, treatment and outcome of lean (LD) compared to overweight and obese people with diabetes clinically classified as type 2 diabetes mellitus (T2DM).

MATERIALS AND METHODS

We combined data from the German DIVE (Diabetes Versorgungs-Evaluation) and DPV (Diabetes-Patienten-Verlaufsdokumentation) databases to produce a large cohort of people with T2DM. The characteristics of people with Body Mass Index (BMI) <25 kg/m2, ≥25-30 kg/m2 and ≥30 kg/m2 aged 30 to 50 years were compared, including demographics, cardiovascular (CV) risk factors, comorbidities and outcomes.

RESULTS

A total of 37,870 people were included in the analysis, 3,191 of these (8.4%) had a BMI < 25 kg/m2. LD reported more nicotine (41.6% of 2,070 vs. 38.1% of 6,070 and 33.4% of 16,823; P<0.001)and alcohol consumption (12.0% of 1,282, 10.3% of 3,594 and 6.6% of 9,418; P<0.001)compared to overweight and obese people. More LD were treated with insulin in comparison to the other subgroups (short acting insulin 33.1% of 3,191 vs. 28.4% of 9,234 and 28.0% of 25,445; P <0.001; long acting insulin 31.3% of 3,191 vs. 28.9% of 9,234 and 29.3% of 25,445; P = 0.043). Regression models adjusted for age, gender and diabetes duration showed a 2.50 times higher odds ratio (OR) for hypoglycemia and a 2.52 higher OR for mortality in LD compared to the BMI subgroup ≥30 kg/m2.

CONCLUSIONS

LD is associated with an increased risk of hypoglycaemia and death. Patients are characterized by male gender, lifestyle habits as smoking and alcohol consumption while cardiovascular comorbidities are less important. In comparison to patients of the other weight groups they are treated with insulin more often and considerably less with metformin.

Pathophysiology of the Effects of Alcohol Abuse on the Endocrine System

Alcohol can permeate virtually every organ and tissue in the body, resulting in tissue injury and organ dysfunction. Considerable evidence indicates that alcohol abuse results in clinical abnormalities of one of the body's most important systems, the endocrine system. This system ensures proper communication between various organs, also interfacing with the immune and nervous systems, and is essential for maintaining a constant internal environment. The endocrine system includes the hypothalamic-pituitary-adrenal axis, the hypothalamic-pituitary-gonadal axis, the hypothalamic-pituitary-thyroid axis, the hypothalamic-pituitary-growth hormone/insulin-like growth factor-1 axis, and the hypothalamic-posterior pituitary axis, as well as other sources of hormones, such as the endocrine pancreas and endocrine adipose tissue. Alcohol abuse disrupts all of these systems and causes hormonal disturbances that may result in various disorders, such as stress intolerance, reproductive dysfunction, thyroid problems, immune abnormalities, and psychological and behavioral disorders. Studies in both humans and animal models have helped shed light on alcohol's effects on various components of the endocrine system and their consequences.

Targeting nitrative stress for attenuating cisplatin-induced downregulation of cochlear LIM domain only 4 and ototoxicity

Cisplatin-induced ototoxicity remains a primary dose-limiting adverse effect of this highly effective anticancer drug. The clinical utility of cisplatin could be enhanced if the signaling pathways that regulate the toxic side-effects are delineated. In previous studies, we reported cisplatin-induced nitration of cochlear proteins and provided the first evidence for nitration and downregulation of cochlear LIM domain only 4 (LMO4) in cisplatin ototoxicity. Here, we extend these findings to define the critical role of nitrative stress in cisplatin-induced downregulation of LMO4 and its consequent ototoxic effects in UBOC1 cell cultures derived from sensory epithelial cells of the inner ear and in CBA/J mice. Cisplatin treatment increased the levels of nitrotyrosine and active caspase 3 in UBOC1 cells, which was detected by immunocytochemical and flow cytometry analysis, respectively. The cisplatin-induced nitrative stress and apoptosis were attenuated by co-treatment with SRI110, a peroxynitrite decomposition catalyst (PNDC), which also attenuated the cisplatin-induced downregulation of LMO4 in a dose-dependent manner. Furthermore, transient overexpression of LMO4 in UBOC1 cells prevented cisplatin-induced cytotoxicity while repression of LMO4 exacerbated cisplatin-induced cell death, indicating a direct link between LMO4 protein levels and cisplatin ototoxicity. Finally, auditory brainstem responses (ABR) recorded from CBA/J mice indicated that co-treatment with SRI110 mitigated cisplatin-induced hearing loss. Together, these results suggest that cisplatin-induced nitrative stress leads to a decrease in the levels of LMO4, downregulation of LMO4 is a critical determinant in cisplatin-induced ototoxicity, and targeting peroxynitrite could be a promising strategy for mitigating cisplatin-induced hearing loss.

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Cisplatin-induced nitrative stress leads to a decrease in the levels of LMO4.

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Downregulation of LMO4 is a critical factor in cisplatin-induced ototoxicity.

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SRI110 appears to be a promising candidate for preventing cisplatin ototoxicity.

Prolonged feeding with guanidinoacetate, a methyl group consumer, exacerbates ethanol-induced liver injury

AIM

To investigate the hypothesis that exposure to guanidinoacetate (GAA, a potent methyl-group consumer) either alone or combined with ethanol intake for a prolonged period of time would cause more advanced liver pathology thus identifying methylation defects as the initiator and stimulator for progressive liver damage.

METHODS

Adult male Wistar rats were fed the control or ethanol Lieber DeCarli diet in the absence or presence of GAA supplementation. At the end of 6 wk of the feeding regimen, various biochemical and histological analyses were conducted.

RESULTS

Contrary to our expectations, we observed that GAA treatment alone resulted in a histologically normal liver without evidence of hepatosteatosis despite persistence of some abnormal biochemical parameters. This protection could result from the generation of creatine from the ingested GAA. Ethanol treatment for 6 wk exhibited changes in liver methionine metabolism and persistence of histological and biochemical defects as reported before. Further, when the rats were fed the GAA-supplemented ethanol diet, similar histological and biochemical changes as observed after 2 wk of combined treatment, including inflammation, macro- and micro-vesicular steatosis and a marked decrease in the methylation index were noted. In addition, rats on the combined treatment exhibited increased liver toxicity and even early fibrotic changes in a subset of animals in this group. The worsening liver pathology could be related to the profound reduction in the hepatic methylation index, an increased accumulation of GAA and the inability of creatine generated to exert its hepato-protective effects in the setting of ethanol.

CONCLUSION

To conclude, prolonged exposure to a methyl consumer superimposed on chronic ethanol consumption causes persistent and pronounced liver damage.

Chronic saponin treatment attenuates damage to the pancreas in chronic alcohol-treated diabetic rats

Background

Chronic heavy alcohol consumption may raise the risk of developing type 2 diabetes mellitus. Saponins inhibit apoptosis of pancreatic islet cells and reduce lipid parameters. The present study was designed to investigate the effect of saponin on chronic ethanol-treated diabetic rats.

Methods

Long–Evans Tokushima Fatty (LETO) and Otsuka Long–Evans Tokushima Fatty (OLETF) rats were pair-fed a Lieber–DeCarli diet with and without 5% ethanol for 12 wks. Two weeks after starting the pair-feeding with the Lieber–DeCarli diet, intraperitoneal injection of saponin was performed for 10 wks. To perform the experiments, rats were divided as follows: LETO-Control (LC), LETO-Ethanol (LE), LETO-Ethanol-Saponin (LES), OLETF-Control (OC), OLETF-Ethanol (OE), and OLETF-Ethanol-Saponin (OES).

Results

The weights of epididymal and mesenteric fat tissue in LES and OES rats were the lightest from among the LETO and OLETF groups, respectively. The secretion of alanine aminotransferase and cholesterol in OES rats decreased significantly compared to their secretion in OC and OE rats, respectively. The islets of the pancreas in LE and OE rats showed clean, unclear, and smaller morphology compared to those of LC, LES, OC, and OES rats. In addition, the expression of insulin in the islets of the pancreas in LC, LES, OC, and OES rats was higher than in LE and OE rats.

Conclusion

Saponin may not only be helpful in alleviating the rapid progress of diabetes due to chronic alcohol consumption in diabetic patients, but may also show potential as an antidiabetic drug candidate for diabetic patients who chronically consume alcohol.

Peroxynitrite: From interception to signaling

Peroxynitrite is a strong oxidant and nitrating species that mediates certain biological effects of superoxide and nitrogen monoxide. These biological effects include oxidative damage to proteins as well as the formation of 3-nitrotyrosyl moieties in proteins. As a consequence, such proteins may lose their activity, gain altered function, or become prone to proteolytic degradation - resulting in modulation of cellular protein turnover and in the modulation of signaling cascades. In analogy to hydrogen peroxide, peroxynitrite may be scavenged by selenoproteins like glutathione peroxidase-1 (GPx-1) or by selenocompounds with a GPx-like activity, such as ebselen; in further analogy to H2O2, peroxiredoxins have also been established as contributors to peroxynitrite reduction. This review covers three aspects of peroxynitrite biochemistry, (i) the interaction of selenocompounds/-proteins with peroxynitrite, (ii) peroxynitrite-induced modulation of cellular proteolysis, and (iii) peroxynitrite-induced modulation of cellular signaling.

Chronic binge alcohol administration impairs glucose-insulin dynamics and decreases adiponectin in asymptomatic simian immunodeficiency virus-infected macaques

Alcohol use disorders (AUDs) frequently exist among persons living with HIV/AIDS. Chronic alcohol consumption, HIV infection, and antiretroviral therapy (ART) are independently associated with impairments in glucose-insulin dynamics. Previous studies from our laboratory have shown that chronic binge alcohol (CBA) administration decreases body mass index, attenuates weight gain, and accentuates skeletal muscle wasting at end-stage disease in non-ART-treated simian immunodeficiency virus (SIV)-infected male rhesus macaques. The aim of this study was to investigate whether CBA and ART alone or in combination alter body composition or glucose-insulin dynamics in SIV-infected male rhesus macaques during the asymptomatic phase of SIV infection. Daily CBA or sucrose (SUC) administration was initiated 3 mo before intrarectal SIV inoculation and continued until the study end point at 11 mo post-SIV infection. ART or placebo was initiated 2.5 mo after SIV infection and continued until study end point. Four treatment groups (SUC/SIV ± ART and CBA/SIV ± ART) were studied. CBA/SIV macaques had significantly decreased circulating adiponectin and resistin levels relative to SUC/SIV macaques and reduced disposition index and acute insulin response to glucose, insulin, and C-peptide release during frequently sampled intravenous glucose tolerance test, irrespective of ART status. No statistically significant differences were observed in homeostatic model assessment-insulin resistance values, body weight, total body fat, abdominal fat, or total lean mass or bone health among the four groups. These findings demonstrate CBA-mediated impairments in glucose-insulin dynamics and adipokine profile in asymptomatic SIV-infected macaques, irrespective of ART.

Monosodium Glutamate Dietary Consumption Decreases Pancreatic β-Cell Mass in Adult Wistar Rats

Background

The amount of dietary monosodium glutamate (MSG) is increasing worldwide, in parallel with the epidemics of metabolic syndrome. Parenteral administration of MSG to rodents induces obesity, hyperglycemia, hyperlipidemia, insulin resistance, and type 2 diabetes. However, the impact of dietary MSG is still being debated. We investigated the morphological and functional effects of prolonged MSG consumption on rat glucose metabolism and on pancreatic islet histology.

Methods

Eighty adult male Wistar rats were randomly subdivided into 4 groups, and test rats in each group were supplemented with MSG for a different duration (1, 3, 6, or 9 months, n=20 for each group). All rats were fed ad libitum with a standard rat chow and water. Ten test rats in each group were provided MSG 2 mg/g body weight/day in drinking water and the 10 remaining rats in each group served as non-MSG treated controls. Oral glucose tolerance tests (OGTT) were performed and serum insulin measured at 9 months. Animals were sacrificed at 1, 3, 6, or 9 months to examine the histopathology of pancreatic islets.

Results

MSG-treated rats had significantly lower pancreatic β-cell mass at 1, 6 and 9 months of study. Islet hemorrhages increased with age in all groups and fibrosis was significantly more frequent in MSG-treated rats at 1 and 3 months. Serum insulin levels and glucose tolerance in MSG-treated and untreated rats were similar at all time points we investigated.

Conclusion

Daily MSG dietary consumption was associated with reduced pancreatic β-cell mass and enhanced hemorrhages and fibrosis, but did not affect glucose homeostasis. We speculate that high dietary MSG intake may exert a negative effect on the pancreas and such effect might become functionally significant in the presence or susceptibility to diabetes or NaCl; future experiments will take these crucial cofactors into account.

Lean diabetes mellitus: An emerging entity in the era of obesity

Much has been published on the characteristics of type 2 diabetes mellitus and its association with the epidemic of obesity. But relatively little is known about the incidence of lean diabetes, progression of disease and fate of the patients with low-normal body mass index (< 25). Studies in developing countries have shown that the clinical characteristics of these patients include history of childhood malnutrition, poor socioeconomic status, relatively early age of onset and absence of ketosis on withdrawal of insulin. In the United States, recent studies showed that the lean, normal weight diabetes is not rare especially among minority populations. They showed that these patients are mainly males, have higher prevalence of insulin use indicating rapid beta cell failure. They might have increased total, cardiovascular and non cardiovascular mortality when compared to obese diabetic patients. In this review, the epidemiologic and clinical features of lean diabetes are presented. The potential causal mechanisms of this emerging diabetes type that may include genetic, autoimmune, acquired and behavioral factors are discussed. The need for studies to further elucidate the causation as well as specific prevention and treatment of lean diabetes is emphasized.

Changes in glucose metabolism and reversion of genes expression in the liver of insulin-resistant rats exposed to malathion. The protective effects of N-acetylcysteine

Organophosphorus pesticides are known to disturb glucose homeostasis and increase incidence of metabolic disorders and diabetes via insulin resistance. The current study investigates the influence of malathion on insulin signaling pathways and the protective effects of N-acetylcysteine (NAC). Malathion (200 mg/kg) and NAC (2 g/l) were administered orally to rats, during 28 consecutive days. Malathion increases plasma glucose, plasma insulin and glycated hemoglobin levels. Further, we observed an increase of insulin resistance biomarkers and a decrease of insulin sensitivity indices. The GP, GSK3β and PEPCK mRNA expressions were amplified by malathion while, the expression of glucokinase gene is down-regulated. On the basis of biochemical and molecular findings, it is concluded that malathion impairs glucose homeostasis through insulin resistance and insulin signaling pathways disruptions in a way to result in a reduced function of insulin into hepatocytes. Otherwise, when malathion-treated rats were compared to NAC supplemented rats, fasting glucose and insulin levels, as well as insulin resistance indices were reduced. Furthermore, NAC restored liver GP and PEPCK expression. N-acetylcysteine showed therapeutic effects against malathion-induced insulin signaling pathways disruption in liver. These data support the concept that antioxidant therapies attenuate insulin resistance and ameliorate insulin sensitivity.