Insulin suppresses endotoxin-induced oxidative, nitrosative, and inflammatory stress in humans

Peak insulin drip rate associated with decreased infections post-solid organ transplant

Infection and rejection outcomes were retrospectively analyzed in patients following liver transplant and separately following heart transplant with patients being stratified by their severity of immediate postoperative insulin resistance as measured by the peak insulin drip rate that was required to reduce glucose levels. For each group, these peak insulin drip rates were divided into quartiles (Q). In liver transplant patients (n = 207), those in Q4 (highest infusion rate) had significantly fewer infections up to 6 months post-transplant (42.3% vs. 60.0%, p = .036) and borderline fewer rejection episodes (25.0% vs. 40.0%, p = .066) compared to Q1-Q3 patients. To confirm these unexpected results, a subsequent similar analysis in heart transplant (n = 188) patients again showed that Q4 patients had significantly fewer infections up to 6 months (19.1% vs. 53.9%, p < .0001) compared to Q1-Q3 patients. Logistic regression in a subset of 103 cardiac transplant patients showed that the maximum glucose during surgery, prior MI, and hypertension were associated with severe insulin resistance (SIR) status, while the presence of pre-existing diabetes and BMI were not. We hypothesize that patients are who are able to mount a more robust counter-regulatory response that causes the insulin resistance may be healthier and thus able to mount a better response to infections.

Melatonin Ameliorates Apoptosis of A549 Cells Exposed to Chicken House PM2.5: A Novel Insight in Poultry Production

The particulate matter 2.5 (PM_2.5) from the chicken production system can cause lung injury and reduce productivity through prolonged breath as it attaches large amounts of harmful substances and microbes. Melatonin has acted to regulate physiological and metabolic disorders and improve growth performance during poultry production. This research would investigate the apoptosis caused by chicken house PM_2.5 on lung pulmonary epithelial cells and the protective action of melatonin. Here, the basal epithelial cells of human lung adenocarcinoma (A549 cells) were subjected to PM_2.5 from the broiler breeding house to investigate the apoptosis induced by PM_2.5 as well as the alleviation of melatonin. The apoptosis was aggravated by PM_2.5 (12.5 and 25 μg/mL) substantially, and the expression of Bcl-2, Bad, Bax, PERK, and CHOP increased dramatically after PM_2.5 treatment. Additionally, the up-regulation of cleaved caspase-9 and cleaved caspase-3 as well as endoplasmic reticulum stress (ERS)-related proteins, including ATF6 and CHOP, was observed due to PM_2.5 exposure. It is worth noting that melatonin could support A549 cells' survival, in which reduced expression of Bax, Bad, cleaved caspase-3, and cleaved caspase-9 appeared. Concurrently, the level of malondialdehyde (MDA) was down-regulated and enhanced the intracellular content of total superoxide dismutase (T-SOD) and catalase (CAT) after treatment by PM_2.5 together with melatonin. Collectively, our study underlined that melatonin exerted an anti-apoptotic action on A549 cells by strengthening their antioxidant capacity.

Lipopolysaccharide and the gut microbiota: Considering structural variation

Systemic inflammation is associated with chronic disease and is purported to be a main pathogenic mechanism underlying metabolic conditions. Microbes harbored in the host gastrointestinal tract release signaling byproducts from their cell wall, such as lipopolysaccharides (LPS), which can act locally and, after crossing the gut barrier and entering circulation, also systemically. Defined as metabolic endotoxemia, elevated concentrations of LPS in circulation are associated with metabolic conditions and chronic disease. As such, measurement of LPS is highly prevalent in animal and human research investigating these states. Indeed, LPS can be a potent stimulant of host immunity but this response depends on the microbial species' origin, a parameter often overlooked in both preclinical and clinical investigations. Indeed, the lipid A portion of LPS is mutable and comprises the main virulence and endotoxic component, thus contributing to the structural and functional diversity among LPSs from microbial species. In this review, we discuss how such structural differences in LPS can induce differential immunological responses in the host.

The effect of short-term intensive insulin therapy on inflammatory cytokines in patients with newly diagnosed type 2 diabetes

BACKGROUND

Diabetes mellitus was a chronic low-grade inflammatory disease and had increased circulating inflammatory cytokines and acute phase proteins. We aimed to identify the changes of inflammatory cytokines in newly diagnosed type 2 diabetic patients after short-term intensive insulin therapy using continuous subcutaneous insulin infusion (CSII).

METHODS

Thirty-three newly diagnosed type 2 diabetic patients were enrolled between September 2020 to December 2020. Expression of 40 inflammatory cytokines of the patients were tested with RayBiotech antibody array before and after 1 week of intensive insulin therapy of CSII. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis was carried out to explore the signaling pathway involved in the therapy.

RESULTS

Five inflammatory cytokines were downregulated significantly after 1 week of CSII therapy. They were interleukin-6 receptor (IL-6R), regulated upon activation normal T-cell expressed and secreted (RANTES), intercellular adhesion molecule-1 (ICAM-1), tissue inhibitor of metalloproteinase-1 (TIMP-1), and platelet-derived growth factor type BB (PDGF-BB) (p < 0.05 and foldchange <0.83). Among patients with baseline glycated hemoglobin (HbA1c) < 10%, three proinflammatory cytokines were decreased significantly after therapy: IL-6R, RANTES, and ICAM-1. As for the patients with baseline HbA1c ≥ 10%, eight inflammatory cytokines were inhibited significantly after the treatment, including ICAM-1, IL-6R, RANTES, TIMP-1, TIMP-2, macrophage inflammatory protein-1 beta (MIP-1β), PDGF-BB, and tumor necrosis factor receptor type II (TNF RII). No matter which subgroup of baseline HbA1c level was considered, the decreased cytokines after CSII therapy were significantly involved in TNF signaling pathway. Nuclear factor-kappa B (NF-κB) signaling pathway was mainly enriched in patients with baseline HbA1c ≥ 10%.

CONCLUSIONS

A panel of 40 inflammatory cytokines, measured by protein microarray, were evaluated for 1 week of CSII treatment in newly diagnosed type 2 diabetic patients. After treatment, many proinflammatory cytokines decreased. In the higher baseline HbA1c subgroup, more proinflammatory cytokines improved. No matter which subgroup of HbA1c level was considered, IL-6R, RANTES, and ICAM-1, which were involved in TNF signaling pathway, decreased significantly after CSII therapy. This was the first report showing that the cytokines of IL-6R, TIMP-2, PDGF-BB, and TNF RII decreased after the CSII therapy.

Insulin as Monotherapy and in Combination with Other Glucose-Lowering Drugs Is Related to Increased Risk of Diagnosis of Pneumonia: A Longitudinal Assessment over Two Years

Objective: Patients with type 2 diabetes mellitus (T2DM) are at an increased risk of developing infectious diseases such as pneumonia. Hitherto, there has been uncertainty as to whether there is a relationship between different antidiabetic drug combinations and development of pneumonia in this specific cohort. Research Design and Methods: In this longitudinal retrospective study we used multiple logistic regression analysis to assess the odds ratios (ORs) of pneumonia during an observational period of 2 years in 31,397 patients with T2DM under previously prescribed stable antidiabetic drug combinations over a duration of 4 years in comparison to 6568 T2DM patients without drug therapy over 4 years adjusted for age, sex and hospitalization duration. Results: Of the 37,965 patients with T2DM, 3720 patients underwent stable monotherapy treatment with insulin (mean age: 66.57 ± 9.72 years), 2939 individuals (mean age: 70.62 ± 8.95 y) received stable statin and insulin therapy, and 1596 patients were treated with a stable combination therapy of metformin, insulin and statins (mean age: 68.27 ± 8.86 y). In comparison to the control group without antidiabetic drugs (mean age: 72.83 ± 9.96 y), individuals undergoing insulin monotherapy (OR: 2.07, CI: 1.54–2.79, p < 0.001); insulin and statin combination therapy (OR: 2.24, CI: 1.68–3.00, p < 0.001); metformin, insulin and statin combination therapy (OR: 2.27, CI: 1.55–3.31, p < 0.001); statin, insulin and dipeptidyl peptidase-4 inhibitor (DPP-IV inhibitor) combination therapy (OR: 4.31, CI: 1.80–10.33, p = 0.001); as well as individuals treated with metformin and sulfonylureas (OR: 1.70, CI: 1.08–2.69, p = 0.02) were at increased risk of receiving a diagnosis of pneumonia. Conclusions: Stable monotherapy with insulin, but also in combination with other antidiabetic drugs, is related to an increased risk of being diagnosed with pneumonia during hospital stays in patients with type 2 diabetes mellitus compared to untreated controls.

Higher admission activated partial thromboplastin time, neutrophil-lymphocyte ratio, serum sodium, and anticoagulant use predict in-hospital COVID-19 mortality in people with Diabetes: Findings from Two University Hospitals in the U.K

AIMS

To create and compare survival models from admission laboratory indices in people hospitalized with coronavirus disease 2019 (COVID-19) with and without diabetes.

METHODS

Retrospective observational study of patients with COVID-19 with or without diabetes admitted to Sheffield Teaching Hospitals from 29 February to 01 May 2020. Predictive variables for in-hospital mortality from COVID-19 were explored using Cox proportional hazard models.

RESULTS

Out of 505 patients, 156 (30.8%) had diabetes mellitus (DM) of which 143 (91.7%) had type 2 diabetes. There were significantly higher in-hospital COVID-19 deaths in those with DM [DM COVID-19 deaths 54 (34.6%) vs. non-DM COVID-19 deaths 88 (25.2%): P < 0.05]. Activated partial thromboplastin time (APPT) > 24 s without anticoagulants (HR 6.38, 95% CI: 1.07-37.87: P = 0.04), APTT > 24 s with anticoagulants (HR 24.01, 95% CI: 3.63-159.01: P < 0.001), neutrophil-lymphocyte ratio > 8 (HR 6.18, 95% CI: 2.36-16.16: P < 0.001), and sodium > 136 mmol/L (HR 3.27, 95% CI: 1.12-9.56: P = 0.03) at admission, were only associated with in-hospital COVID-19 mortality for those with diabetes.

CONCLUSIONS

At admission, elevated APTT with or without anticoagulants, neutrophil-lymphocyte ratio and serum sodium are unique factors that predict in-hospital COVID-19 mortality in patients with diabetes compared to those without. This novel finding may lead to research into haematological and biochemical mechanisms to understand why those with diabetes are more susceptible to poor outcomes when infected with Covid-19, and contribute to identification of those most at risk when admitted to hospital.

A Bittersweet Response to Infection in Diabetes; Targeting Neutrophils to Modify Inflammation and Improve Host Immunity

Chronic and recurrent infections occur commonly in both type 1 and type 2 diabetes (T1D, T2D) and increase patient morbidity and mortality. Neutrophils are professional phagocytes of the innate immune system that are critical in pathogen handling. Neutrophil responses to infection are dysregulated in diabetes, predominantly mediated by persistent hyperglycaemia; the chief biochemical abnormality in T1D and T2D. Therapeutically enhancing host immunity in diabetes to improve infection resolution is an expanding area of research. Individuals with diabetes are also at an increased risk of severe coronavirus disease 2019 (COVID-19), highlighting the need for re-invigorated and urgent focus on this field. The aim of this review is to explore the breadth of previous literature investigating neutrophil function in both T1D and T2D, in order to understand the complex neutrophil phenotype present in this disease and also to focus on the development of new therapies to improve aberrant neutrophil function in diabetes. Existing literature illustrates a dual neutrophil dysfunction in diabetes. Key pathogen handling mechanisms of neutrophil recruitment, chemotaxis, phagocytosis and intracellular reactive oxygen species (ROS) production are decreased in diabetes, weakening the immune response to infection. However, pro-inflammatory neutrophil pathways, mainly neutrophil extracellular trap (NET) formation, extracellular ROS generation and pro-inflammatory cytokine generation, are significantly upregulated, causing damage to the host and perpetuating inflammation. Reducing these proinflammatory outputs therapeutically is emerging as a credible strategy to improve infection resolution in diabetes, and also more recently COVID-19. Future research needs to drive forward the exploration of novel treatments to improve infection resolution in T1D and T2D to improve patient morbidity and mortality.

Insulin Rescued MCP-1-Suppressed Cholesterol Efflux to Large HDL2 Particles via ABCA1, ABCG1, SR-BI and PI3K/Akt Activation in Adipocytes

Purpose

Intracellular cholesterol imbalance plays an important role in adipocyte dysfunction of obesity. However, it is unclear whether obesity induced monocyte chemoattractant protein-1 (MCP-1) causes the adipocyte cholesterol imbalance. In this study, we hypothesize that MCP-1 impairs cholesterol efflux of adipocytes to HDL2 and insulin rescues this process.

Methods

We recruited coronary artery disease (CAD) patients with obesity and overweight to analyze the association between MCP-1 and HDL2-C by Pearson correlation coefficients. We performed [³H]-cholesterol efflux assay to demonstrate the effect of MCP-1 and insulin on cholesterol efflux from 3T3-L1 adipocytes to large HDL2 particles. Western blot, RT-qPCR, cell-surface protein assay, and confocal microscopy were performed to determine the regulatory mechanism.

Results

Plasma MCP-1 concentrations were negatively correlated with HDL2-C in CAD patients with obesity and overweight (r = −0.60, p < 0.001). In differentiated 3T3-L1 adipocytes, MCP-1 reduced cholesterol efflux to large HDL2 particles by 55.4% via decreasing ATP-binding cassette A1 (ABCA1), ABCG1, and scavenger receptor class B type I (SR-BI) expression. Intriguingly, insulin rescued MCP-1 mediated-inhibition of cholesterol efflux to HDL2 in an Akt phosphorylation-dependent manner. The rescue efficacy of insulin was 138.2% for HDL2. Moreover, insulin increased mRNA and protein expression of ABCA1, ABCG1, and SR-BI at both transcriptional and translational levels via the PI3K/Akt activation.

Conclusions

These findings indicate that MCP-1 impairs cholesterol efflux to large HDL2 particles in adipocytes, which is reversed by insulin via the upregulation of ABCA1, ABCG1, and SR-BI. Therefore, insulin might improve cholesterol imbalance by an anti-inflammatory effect in adipocytes. Clinical trial registration number: ChiCTR2000033297; Date of registration: 2020/05/ 27; Retrospectively registered.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10557-021-07166-2.

The Cytokine Profiles and Immune Response Are Increased in COVID-19 Patients with Type 2 Diabetes Mellitus

The induction of inflammation and cytokine storm was proposed to play a critical role in COVID-19. This study is aimed at investigating the relationship between glucose metabolism and the inflammatory state of inpatients with COVID-19. 71 inpatients with COVID-19 were classified into nondiabetes mellitus (NDM) group, impaired fasting glucose (IFG) group, and diabetes mellitus (DM) group. The average hospitalization days were significantly shorter in DM patients when compared with patients in the IFG group and NDM group. CD4+ T cell percentage was higher while CD8+ T cells percentage was lower in the DM group than those in the NDM group. The serum levels of IL-6, IL-2, IL-10, and INF-γ in the DM group were upregulated when compared with those in the NDM group. The serum levels of TNF-α, IL-4, IL-2, IL-10, and INF-γ were significantly higher in the DM group than those in the IFG group. A significant difference was observed in CD4+ T cell, CD4+/CD8+ ratio percentage, IL-6, and IL-10 between the NDM group and DM group with adjusted BMI. In conclusion, COVID-19 patients with elevated glucose levels have promoted cytokine profiles and immune response.

Macronutrient-Mediated Inflammation and Oxidative Stress: Relevance to Insulin Resistance, Obesity, and Atherogenesis

CONTEXT

The intake of macronutrients as components of a Western dietary pattern leads to oxidative stress and inflammation.

EVIDENCE ACQUISITION

Data were largely retrieved from our previous and most recent work. PubMed and Google Scholar were searched for recent articles on the effect of macronutrients/dietary intake on inflammation, insulin resistance, obesity, and atherogenesis. The most relevant, high-quality articles were included in our review.

EVIDENCE SYNTHESIS

Our previous work has demonstrated the molecular mechanisms of macronutrient-mediated oxidative stress and inflammation. With the induction of inflammation, proinflammatory molecules potentially interfere with insulin signal transduction, thus causing insulin resistance. In addition, other molecules promote atherogenic inflammation. More recently, our work has also shown that certain foods are noninflammatory or anti-inflammatory and thus, do not interfere with insulin signaling. Finally, as obesity is induced by chronic excessive caloric intake, it is characterized by an increase in the expression of proinflammatory molecules, which are induced acutely by a Western diet. Caloric restriction, including fasting, is associated with a reduction in oxidative and inflammatory stress.

CONCLUSIONS

This review summarizes and attempts to provide an up-to-date profile of the molecular mechanisms involved in macronutrient-mediated oxidative/inflammatory stress and its potential consequences. An understanding of these underlying mechanisms is crucial for making appropriate dietary choices.

Effect of Hypoglycemia on Inflammatory Responses and the Response to Low-Dose Endotoxemia in Humans

CONTEXT

Hypoglycemia is emerging as a risk for cardiovascular events in diabetes. We hypothesized that hypoglycemia activates the innate immune system, which is known to increase cardiovascular risk.

OBJECTIVE

To determine whether hypoglycemia modifies subsequent innate immune system responses.

DESIGN AND SETTING

Single-blinded, prospective study of three independent parallel groups.

PARTICIPANTS AND INTERVENTIONS

Twenty-four healthy participants underwent either a hyperinsulinemic-hypoglycemic (2.5 mmol/L), euglycemic (6.0 mmol/L), or sham-saline clamp (n = 8 for each group). After 48 hours, all participants received low-dose (0.3 ng/kg) intravenous endotoxin.

MAIN OUTCOME MEASURES

We studied in-vivo monocyte mobilization and monocyte-platelet interactions.

RESULTS

Hypoglycemia increased total leukocytes (9.98 ± 1.14 × 109/L vs euglycemia 4.38 ± 0.53 × 109/L, P < 0.001; vs sham-saline 4.76 ± 0.36 × 109/L, P < 0.001) (mean ± SEM), mobilized proinflammatory intermediate monocytes (42.20 ± 7.52/μL vs euglycemia 20.66 ± 3.43/μL, P < 0.01; vs sham-saline 26.20 ± 3.86/μL, P < 0.05), and nonclassic monocytes (36.16 ± 4.66/μL vs euglycemia 12.72 ± 2.42/μL, P < 0.001; vs sham-saline 19.05 ± 3.81/μL, P < 0.001). Following hypoglycemia vs euglycemia, platelet aggregation to agonist (area under the curve) increased (73.87 ± 7.30 vs 52.50 ± 4.04, P < 0.05) and formation of monocyte-platelet aggregates increased (96.05 ± 14.51/μL vs 49.32 ± 6.41/μL, P < 0.05). Within monocyte subsets, hypoglycemia increased aggregation of intermediate monocytes (10.51 ± 1.42/μL vs euglycemia 4.19 ± 1.08/μL, P < 0.05; vs sham-saline 3.81± 1.42/μL, P < 0.05) and nonclassic monocytes (9.53 ± 1.08/μL vs euglycemia 2.86 ± 0.72/μL, P < 0.01; vs sham-saline 3.08 ± 1.01/μL, P < 0.05), with platelets compared with controls. Hypoglycemia led to greater leukocyte mobilization in response to subsequent low-dose endotoxin challenge (10.96 ± 0.97 vs euglycemia 8.21 ± 0.85 × 109/L, P < 0.05).

CONCLUSIONS

Hypoglycemia mobilizes monocytes, increases platelet reactivity, promotes interaction between platelets and proinflammatory monocytes, and potentiates the subsequent immune response to endotoxin. These changes may contribute to increased cardiovascular risk observed in people with diabetes.

Prolonged Prothrombotic Effects of Antecedent Hypoglycemia in Individuals With Type 2 Diabetes

OBJECTIVE

Hypoglycemia has been linked to persistent increases in cardiovascular (CV) mortality in type 2 diabetes after the event. Our aim was to examine acute and downstream effects of hypoglycemia on markers of thrombosis risk and inflammation in type 2 diabetes.

RESEARCH DESIGN AND METHODS

Twelve individuals with type 2 diabetes with no history of CV disease and 11 age- and BMI-matched volunteers without diabetes underwent paired hyperinsulinemic-euglycemic (glucose 6 mmol/L for two 60-min periods) and hypoglycemic (glucose 2.5 mmol/L for two 60-min periods) clamps on separate occasions on day 0. Fibrin clot properties, platelet reactivity, and inflammatory markers were measured at baseline, end of and after recovery from the initial clamp, day 1, and day 7 using validated assays and electron microscopy.

RESULTS

Euglycemic hyperinsulinemia reduced platelet reactivity, decreased fibrin clot density, and improved fibrinolytic efficiency in both groups. Platelet reactivity and aggregation increased during acute hypoglycemia in both groups, resolving at recovery. In type 2 diabetes, clot lysis times and clot maximum absorbance increased up to day 7 (P = 0.002 and 0.001 vs. euglycemia, respectively), but clots from control subjects without diabetes showed limited changes. Fibrin network density increased Δ 1.15 ± 0.28 fibers/μm² at day 7 after the hypoglycemic clamp (P < 0.01 for glycemic arm), whereas fibrinogen and complement C3 increased after hypoglycemia up to day 7 in type 2 diabetes only.

CONCLUSIONS

Antecedent hypoglycemia has acute and persistent prothrombotic effects, lasting at least 7 days, that were enhanced in individuals with type 2 diabetes. These findings identify mechanisms by which hypoglycemia might increase short- and medium-term risk of CV mortality.

The effects of insulin on the inflammatory activity of BV2 microglia

Microglia are the macrophages of the central nervous system (CNS), which function to monitor and maintain homeostasis. Microglial activation occurs after CNS injury, infection or disease. Prolonged microglial activation is detrimental to the CNS as they produce nitric oxide (NO), reactive oxygen species (ROS) and pro-inflammatory cytokines, resulting in neuronal cell dysfunction and death. Microglial activation is implicated in the neurological deficits following traumatic brain injury (TBI) and Alzheimer's disease. Intranasal insulin administration is a promising treatment of Alzheimer's disease and TBI. However, the exact effect of insulin on microglia is currently unclear. The goal of this study was therefore to examine the effect of insulin administration on activated microglia. The microglial cell line BV2 were exposed to a pro-inflammatory stimulus, lipopolysaccharide (LPS), followed by insulin administration. Outcome measures were conducted at 24 hours after treatment. In vitro assays quantified NO and ROS production. Western blot, immunocytochemistry and phagocytosis assay further examined the effect of insulin on microglial activity. Insulin treatment significantly reduced NO, ROS and TNFα production and increased phagocytic activity. Insulin treatment also significantly reduced iNOS expression, but had no significant effect on any other M1 or M2 macrophage polarization marker examined. These data suggest that insulin has very specific effects to reduce pro-inflammatory or chemoattractant properties of microglia, and this may be one mechanism by which insulin has beneficial effects in CNS injury or neurodegenerative conditions.

Insulin alleviates mitochondrial oxidative stress involving upregulation of superoxide dismutase 2 and uncoupling protein 2 in septic acute kidney injury

The aim of the present study was to explore the effects and mechanisms of insulin on mitochondrial oxidative stress in septic acute kidney injury (AKI). Male Sprague Dawley rats were divided randomly into four groups: Control group, sham surgery group, cecal ligation and puncture (CLP) group, and CLP plus insulin group. Blood specimens and kidney tissues were obtained at 12 and 24 h after surgery as separate experiments. Analyses of histology and indicators of renal injury [blood urea nitrogen (BUN) and serum creatinine (CRE) and neutrophil gelatinase-associated lipocalin (NGAL)], mitochondrial function [adenosine triphosphate (ATP) and mitochondrial membrane potential (MMP)], oxidative stress [inducible nitric oxide synthase (iNOS), reactive oxygen species (ROS) and nitric oxide (NO)], endogenous antioxidant systems [superoxide dismutase (SOD) and glutathione (GSH)] as well as the expression of uncoupling protein (UCP), PINK1 protein (a major mediator of mitophagy), PGC1α protein (a major regulator of mitochondrial biogenesis) were performed. Compared with CLP group, the CLP plus insulin group had milder histological damage, higher levels of ATP and MMP as well as lower levels of BUN, serum CRE and NGAL, intrarenal iNOS, mitochondrial ROS and total NO. Moreover, the CLP plus insulin group demonstrated increased expression of SOD2 and UCP2. In contrast, insulin administration suppressed mitophagy meanwhile did not upregulate total GSH and induce mitochondrial biogenesis following CLP. These findings indicated that the upregulation of SOD2 and UCP2 may be involved in insulin protecting against mitochondrial oxidative stress in septic AKI.

The association of admission hyperglycaemia and adverse clinical outcome in medical emergencies: the multinational, prospective, observational TRIAGE study

AIMS

The clinical relevance of hyperglycaemia in an emergency department population remains incompletely understood. We investigated the association between admission blood glucose levels and adverse clinical outcomes in a large emergency department cohort.

METHODS

We prospectively enrolled 7132 adult medical patients seeking emergency department care in three tertiary care hospitals in Switzerland, France and the USA. We used adjusted multivariable logistic regression models to examine the association between admission blood glucose levels and 30-day mortality, as well as adverse clinical course stratified by pre-existing diabetes and principal medical diagnoses.

RESULTS

In 6044 people without diabetes (84.7%), severe hyperglycaemia, defined as a glucose level of > 11.1 mmol/l (200 mg/dl), was associated with a doubling in the risk of 30-day mortality [adjusted odds ratio (OR) 1.9; 95% confidence interval (95% CI), 1.1 to 3.3; P = 0.018] and a three-fold increase in the risk of intensive care unit admission (adjusted OR 3.0; 95% CI, 1.9 to 4.9; P < 0.001). These associations were similar among different diagnoses. In the population with diabetes (n = 1088), no association with 30-day mortality was found (adjusted OR 1.0; 95% CI, 0.6 to 1.8; P for interaction = 0.001), whereas the association with intensive care unit admission was weaker (adjusted OR 2.4; 95% CI, 1.5 to 4.1; P for interaction = 0.011). Overall 30-day mortality was higher in those with diabetes than in those without (6.1 vs. 4.4%, P = 0.015).

CONCLUSIONS

In this large medical emergency department patient cohort, admission hyperglycaemia was strongly associated with adverse clinical course in people without diabetes. (Clinical Trial Registry No: NCT01768494).

Effects of rumen-protected Capsicum oleoresin on immune responses in dairy cows intravenously challenged with lipopolysaccharide

The objective of this experiment was to investigate the effects of rumen-protected Capsicum oleoresin (RPC) on productivity and immune responses including feed intake, milk yield and composition, white and red blood cells, lipid peroxidation, and blood concentration of cortisol, haptoglobin, glucose, and insulin in lactating dairy cows experimentally challenged with lipopolysaccharide (LPS). The experiment was a replicated 3 × 3 Latin square design with 9 multiparous Holstein cows in three 28-d periods. Treatments were 0 (control), 100, and 200 mg of RPC/cow per day, mixed with small portions of the total mixed ration and top-dressed. Bacterial LPS was intravenously administered at 1.0 μg/kg of body weight in the last week of each experimental period, and blood samples were collected at 0, 2, 4, 8, and 24 h after administration. Dry matter intake, milk yield, and white blood cells including neutrophils, lymphocytes, monocytes, and eosinophils were decreased, and rectal temperature, hemoglobin, and serum concentrations of cortisol and haptoglobin were increased by LPS. Red blood cells, platelets, and plasma concentration of thiobarbituric acid reactive substances were not affected by LPS. Dry matter intake, milk yield, and milk composition in the 5 d post-LPS challenge were not affected by RPC. Rectal temperature, white blood cells, red blood cells, hemoglobin, and platelets were also not affected by RPC. Compared with the control, RPC tended to decrease cortisol at 2 h following LPS challenge and decreased haptoglobin concentration in serum across sampling points. Concentration of thiobarbituric acid reactive substances in plasma was decreased by RPC at 24 h post-LPS challenge. Glucose and insulin were not affected by RPC, but serum insulin concentration at 8 h was lowered by RPC compared to the control. Collectively, RPC had no or subtle effects on feed intake, milk yield and composition, rectal temperature, white and red blood cells, and serum glucose and insulin concentration in dairy cows challenged by LPS. However, RPC tended to decrease cortisol and decreased concentrations of haptoglobin and thiobarbituric acid reactive substances in blood following LPS challenge. Data suggest that dietary supplementation of RPC may modulate acute phase responses induced by bacterial infection in lactating dairy cows.

Potential mediators linking gut bacteria to metabolic health: a critical view

Growing evidence suggests that the bacteria present in our gut may play a role in mediating the effect of genetics and lifestyle on obesity and metabolic diseases. Most of the current literature on gut bacteria consists of cross‐sectional and correlative studies, rendering it difficult to make any causal inferences as to the influence of gut bacteria on obesity and related metabolic disorders. Interventions with germ‐free animals, treatment with antibiotic agents, and microbial transfer experiments have provided some evidence that disturbances in gut bacteria may causally contribute to obesity‐related insulin resistance and adipose tissue inflammation. Several potential mediators have been hypothesized to link the activity and composition of gut bacteria to insulin resistance and adipose tissue function, including lipopolysaccharide, angiopoietin‐like protein 4, bile acids and short‐chain fatty acids. In this review we critically evaluate the current evidence related to the direct role of gut bacteria in obesity‐related metabolic perturbations, with a focus on insulin resistance and adipose tissue inflammation. It is concluded that the knowledge base in support of a role for the gut microbiota in metabolic regulation and in particular insulin resistance and adipose tissue inflammation needs to be strengthened.

Insulin-Dependent Regulation of mTORC2-Akt-FoxO Suppresses TLR4 Signaling in Human Leukocytes: Relevance to Type 2 Diabetes

Leukocyte signaling in patients with systemic insulin resistance is largely unexplored. We recently discovered the presence of multiple Toll-like receptor 4 (TLR4) signaling intermediates in leukocytes from patients with type 2 diabetes or acute insulin resistance associated with cardiopulmonary bypass surgery. We extend this work to show that in addition to matrix metalloproteinase 9, hypoxia-inducible factor 1α, and cleaved AMPKα, patient leukocytes also express IRS-1 phosphorylated on Ser(312), Akt phosphorylated on Thr(308), and elevated TLR4 expression. Similar signaling intermediates were detected in leukocytes and neutrophils treated with lipopolysaccharide (LPS), a ligand of TLR4, in vitro. In contrast, insulin, but not LPS, induced mammalian target of rapamycin complex 2 (mTORC2)-dependent phosphorylation of Akt on Ser(473) and FoxO1/O3a on Thr(24/32) in leukocytes and neutrophils. Insulin suppressed LPS-induced responses in a dose- and time-dependent manner. AS1842856, a FoxO1 inhibitor, also suppressed TLR4 signaling. We propose that insulin is a homeostatic regulator of leukocyte responses to LPS/TLR4 and that the signaling intermediates expressed in leukocytes of patients with type 2 diabetes indicate TLR4 signaling dominance and deficient insulin signaling. The data suggest that insulin suppresses LPS/TLR4 signals in leukocytes through the mTORC2-Akt-FoxO signaling axis. Better understanding of leukocyte signaling in patients with type 2 diabetes may shed new light on disease causation and progression.

The Role of HMGB1 in the Pathogenesis of Type 2 Diabetes

Significance. With an alarming increase in recent years, diabetes mellitus has become a global challenge. Despite advances in treatment of diabetes mellitus, currently, medications available are unable to control the progression of diabetes and its complications. Growing evidence suggests that inflammation is an important pathogenic mediator in the development of diabetes mellitus. The perspectives including suggestions for new therapies involving the shift from metabolic stress to inflammation should be taken into account. Critical Issues. High-mobility group box 1 (HMGB1), a nonhistone nuclear protein regulating gene expression, was rediscovered as an endogenous danger signal molecule to trigger inflammatory responses when released into extracellular milieu in the late 1990s. Given the similarities of inflammatory response in the development of T2D, we will discuss the potential implication of HMGB1 in the pathogenesis of T2D. Importantly, we will summarize and renovate the role of HMGB1 and HMGB1-mediated inflammatory pathways in adipose tissue inflammation, insulin resistance, and islet dysfunction. Future Directions. HMGB1 and its downstream receptors RAGE and TLRs may serve as potential antidiabetic targets. Current and forthcoming projects in this territory will pave the way for prospective approaches targeting the center of HMGB1-mediated inflammation to improve T2D and its complications.

PARK7/DJ-1 dysregulation by oxidative stress leads to magnesium deficiency: implications in degenerative and chronic diseases

Disturbed magnesium (Mg(2+)) homoeostasis and increased levels of OS (oxidative stress) are associated with poor clinical outcomes in patients suffering from neurodegenerative, cardiovascular and metabolic diseases. Data from clinical and animal studies suggest that MD (Mg(2+) deficiency) is correlated with increased production of ROS (reactive oxygen species) in cells, but a straightforward causal relationship (including molecular mechanisms) between the two conditions is lacking. The multifactorial protein PARK7/DJ-1 is a major antioxidant protein, playing a key role in cellular redox homoeostasis, and is a positive regulator of AR (androgen receptor)-dependent transcription. SLC41A1 (solute carrier family 41 member 1), the gene encoding a ubiquitous cellular Mg(2+)E (Mg(2+)efflux) system, has been shown to be regulated by activated AR. We hypothesize that overexpression/up-regulation of PARK7/DJ-1, attributable to OS and related activation of AR, is an important event regulating the expression of SLC41A1 and consequently, modulating the Mg(2+)E capacity. This would involve changes in the transcriptional activity of PARK7/DJ-1, AR and SLC41A1, which may serve as biomarkers of intracellular MD and may have clinical relevance. Imipramine, in use as an antidepressant, has been shown to reduce the Mg(2+)E activity of SLC41A1 and OS. We therefore hypothesize further that administration of imipramine or related drugs will be beneficial in MD- and OS-associated diseases, especially when combined with Mg(2+) supplementation. If proved true, the OS-responsive functional axis, PARK7/DJ-1-AR-SLC41A1, may be a putative mechanism underlying intracellular MD secondary to OS caused by pro-oxidative stimuli, including extracellular MD. Furthermore, it will advance our understanding of the link between OS and MD.

The effects of insulin pre-administration in mice exposed to ethanol: alleviating hepatic oxidative injury through anti-oxidative, anti-apoptotic activities and deteriorating hepatic steatosis through SRBEP-1c activation

Alcoholic liver disease (ALD) has become an important liver disease hazard to public and personal health. Oxidative stress is believed to be responsible for the pathological changes in ALD. Previous studies have showed that insulin, a classic regulator of glucose metabolism, has significant anti-oxidative function and plays an important role in maintaining the redox balance. For addressing the effects and mechanisms of insulin pre-administration on ethanol-induced liver oxidative injury, we investigated histopathology, inflammatory factors, apoptosis, mitochondrial dysfunction, oxidative stress, antioxidant defense system, ethanol metabolic enzymes and lipid disorder in liver of ethanol-exposed mice pretreatment with insulin or not. There are several novel findings in our study. First, we found insulin pre-administration alleviated acute ethanol exposure-induced liver injury and inflammation reflected by the decrease of serum AST and ALT activities, the improvement of pathological alteration and the inhibition of TNF-α and IL-6 expressions. Second, insulin pre-administration could significantly reduce apoptosis and ameliorate mitochondrial dysfunction in liver of mice exposed to ethanol, supporting by decreasing caspases-3 activities and the ratio of Bax/Bcl-2, increasing mitochondrial viability and mitochondrial oxygen consumption, inhibition of the decline of ATP levels and mitochondrial ROS accumulation. Third, insulin pre-administration prevented ethanol-mediated oxidative stress and enhance antioxidant defense system, which is evaluated by the decline of MDA levels and the rise of GSH/GSSG, the up-regulations of antioxidant enzymes CAT, SOD, GR through Nrf-2 dependent pathway. Forth, the modification of ethanol metabolism pathway such as the inhibition of CYP2E1, the activation of ALDH might be involved in the anti-oxidative and protective effects exerted by insulin pre-administration against acute ethanol exposure in mice. Finally, insulin pre-administration deteriorated hepatic steatosis in mice exposed to ethanol might be through SRBEP-1c activation. In summary, these results indicated that insulin pre-administration effectively alleviated liver oxidative injury through anti-inflammatory, anti-oxidative and anti-apoptotic activities but also deteriorated hepatic steatosis through SRBEP-1c activation in mice exposed to ethanol. Our study provided novel insight about the effects and mechanisms of insulin on ethanol-induced liver injury.

Decreased insulin secretion and incretin concentrations and increased glucagon concentrations after a high-fat meal when compared with a high-fruit and -fiber meal

This study was conducted to investigate whether a high-fat/high-carbohydrate (HFHC) meal induces an increase in plasma concentrations of glucagon, dipeptidyl peptidase-IV (DPP-IV), and CD26 expression in mononuclear cells (MNC) while reducing insulin, C-peptide, proinsulin, GIP, and GLP-1 concentrations. Ten healthy normal subjects were given either a 910-calorie HFHC meal or an American Heart Association (AHA) meal rich in fruit and fiber during the first visit and the other meal during the second visit in crossover design. Blood samples were collected at baseline and at 15, 30, 45, 60, 75, 90, 120, 180, and 300 min following the meal. There was a significantly greater increase in glucose concentrations and lower increase in postprandial insulin, C-peptide, and proinsulin concentrations and lower insulin/glucose ratios following the HFHC meal. HFHC meal intake induced marked increases in plasma glucagon and DPP-IV concentrations and an increase in CD26 mRNA expression in MNC compared with the AHA meal. In addition, the HFHC meal induced a reduction in GIP and peak GLP-1 secretion compared with the AHA meal. This was associated with a significantly greater increase in oxidative stress and proinflammatory mediators including, ROS generation, TNFα, and IL-1β mRNA expression and plasma concentrations of TBARS, FFA, and LPS. We conclude that the proinflammatory HFHC meals result in lower insulin, C-peptide, proinsulin, and GIP secretion in association with higher plasma glucagon and DPP-IV concentrations and CD26 expression in MNC compared with the AHA meal.

Suppressive effect of insulin on the gene expression and plasma concentrations of mediators of asthmatic inflammation

BACKGROUND AND HYPOTHESIS

Following our recent demonstration that the chronic inflammatory and insulin resistant state of obesity is associated with an increase in the expression of mediators known to contribute to the pathogenesis of asthma and that weight loss after gastric bypass surgery results in the reduction of these genes, we have now hypothesized that insulin suppresses the cellular expression and plasma concentrations of these mediators.

METHODS

The expression of IL-4, LIGHT, LTBR, ADAM-33, and TSLP in MNC and plasma concentrations of LIGHT, TGF-β1, MMP-9, MCP-1, TSLP, and NOM in obese patients with T2DM were measured before, during, and after the infusion of a low dose (2 U/h) infusion of insulin for 4 hours. The patients were also infused with dextrose or saline for 4 hours on two separate visits and served as controls. Results. Following insulin infusion, the mRNA expression of IL-4, ADAM-33, LIGHT, and LTBR mRNA expression fell significantly (P < 0.05 for all). There was also a concomitant reduction in plasma NOM, LIGHT, TGF-β1, MCP-1, and MMP-9 concentrations.

CONCLUSIONS

Insulin suppresses the expression of these genes and mediators related to asthma and may, therefore, have a potential role in the treatment of asthma.

Fructooligosaccharide raftilose reduces the mycophenolate mofetil-induced complications: Hematological and biochemical alterations

Mycophenolate mofetil (MMF) is a selective inhibitor of Inosine-5'-monophosphate dehydrogenase. Gastrointestinal (GI) disturbances in immature ones are reported for MMF-induced compilations, which in the case of occurrence dose reduction is required. Thus, in the present study, the fructooligosaccharide raftilose(®) (RFT) was co-administrated with MMF to estimate the protective effect of RFT against MMF-induced GI complications. Thirty six immature male Wistar rats were divided into six groups including: Control (normal saline), RFT-treated (100 mg kg(-1)), MMF-treated (20 mg kg(-1)), MMF + LRFT (50 mg kg(-1)), MMF + MRFT (100 mg kg(-1)) and MMF + HRFT (200 mg kg(-1)) groups. The hematocrit (Hct), lymphocyte/total WBC, feces water content and pH were analyzed. Moreover, the hepatic functional tests, kidney-related biomarkers, lipid and protein profiles, total antioxidant capacity (TAC), malondialdehyde (MDA) and nitric oxide (NO) contents were assessed. Co-administration of RFT stabilized the MMF-reduced body weight. The MMF significantly diminished Hct and lymph/total WBC (p < 0.05). Only MRFT enhanced the lymphocyte/total WBC. Increased water content, no changes in feces pH, increased serum ALT and AST, no alteration in urea and mild enhancement in creatinine were demonstrated in MMF-received animals. However, RFT at low dose ameliorated the feces parameters and reduced ALT. No significant changes were demonstrated for serum lipid and protein profiles in MMF- and RFT + MMF-treated groups. The RFT enhanced the serum TAC, reduced MDA and NO contents. In conclusion, our data suggested that RFT could be considered as an effective agent to subsidize the MMF-induced clinical, hematological and biochemical disorders.

Insulin Control of Blood Glucose and GLUT4 Expression in the Skeletal Muscle of Septic Rats

BACKGROUND

Insulin resistance is common in septic patients. The level at which the serum glucose should be maintained using insulin infusions for optimal utilization by skeletal muscles is not yet established.

OBJECTIVE

The objective of the present study was to compare glucose transporter 4 (GLUT4) mRNA and GLUT4 expression and glucose utilization at the recommended glucose levels of 6-8 mmol/L (110-140 mg/dL) and 8-10 mmol/L (140-180 mg/dL) in septic rats.

SUBJECTS AND METHODS

This was a prospective randomized study using 44 Sprague-Dawley rats (260-330 g). Rats were anaesthetized with gaseous diethyl ether. Catheters were implanted into the jugular vein and artery. Following a laparotomy, rats in the experimental group (n = 36) were rendered septic by standard caecal ligation and puncture (CLP) and intraperitoneal lipopolysaccharide (LPS) infusion (O111:[B4], 1 mg/kg). Control animals (n = 8) underwent laparotomy, but no caecal ligation or puncture and no LPS injection. Four experimental groups were studied: sham-operated control, sepsis treated with fluid maintenance only, sepsis treated with fluid and insulin infusion controlling blood glucose concentration at 6-8 mmol/L and sepsis treated with fluid and insulin infusion controlling blood glucose concentration at 8-10 mmol/L. Hyperinsulinaemic-euglycaemic clamp experiment was done before fluid maintenance and insulin treatment to calculate average glucose infusion rate.

RESULTS

All septic rats were markedly hyperglycaemic compared with sham-operated controls two hours after operation. Glucose infusion rate during hyperinsulinaemic-euglycaemic clamp experiment was slower in septic rats, suggesting that they were insulin resistant. At the 12th and 24th hour, skeletal muscle was taken to observe pathological change and analyse the GLUT4 mRNA and GLUT4 levels. There were more inflammatory cells, less GLUT4 mRNA and GLUT4 expression in the skeletal muscles of septic rats. Insulin increased the expression of GLUT4 mRNA and GLUT4 in the skeletal muscle of septic rats. Among all septic rats, the expression of GLUT4 mRNA and GLUT4 was more in the 8-10 mmol/L group.

CONCLUSION

Blood glucose concentration of 8-10 mmol/L results in more glucose utilization than 6-8 mmol/L in the skeletal muscle of septic rats during insulin therapy.

Circulatory changes of the novel adipokine adipolin/CTRP12 in response to metformin treatment and an oral glucose challenge in humans

OBJECTIVE

Adipolin/CTRP12 is a novel adipokine with anti-inflammatory and glucose-lowering properties in rodents. We sought to investigate the effects of metformin treatment (850 mg twice daily for 6 months) and a 2 h 75 g oral glucose tolerance test (OGTT) on serum adipolin concentrations in humans.

DESIGN

Cross-sectional study [PCOS (n = 83) and control (n = 39) subjects]. Serum adipolin was measured by ELISA. Metformin treatment (850 mg twice daily for 6 months) was offered to all women with PCOS, 34 women participated but 21 women completed 6 months of metformin therapy. Reasons for subjects not completing the study were nausea and gastrointestinal side effects (n = 4), pregnancies (n = 5), noncompliance (n = 2) and loss of contact (n = 2).

RESULTS

Metformin treatment (850 mg twice daily for 6 months) substantially increased serum adipolin concentrations (P < 0·05) in women with polycystic ovary syndrome (PCOS), a pro-inflammatory state associated with obesity, diabetes, dyslipidaemia and atherosclerosis. Furthermore, changes in waist-hip ratio, glucose, triglycerides, CRP and carotid intima media thickness showed significant negative associations with changes in adipolin levels (P < 0·05, P < 0·01); in multiple regression analyses, only changes in glucose were predictive of changes in adipolin levels (β = -0·570, P = 0·009). Serum adipolin decreased significantly in response to the OGTT in PCOS and control subjects at 90 min (P < 0·05) and 120 min (P < 0·01).

CONCLUSIONS

Adipolin and/or novel pharmacologic agents that increase adipolin's circulating concentrations might constitute a novel approach in the treatment of insulin resistant states.

Activation of the bile acid receptor TGR5 enhances LPS-induced inflammatory responses in a human monocytic cell line

INTRODUCTION

Bile acids are recognized as signaling molecules, mediating their effects both through the cell surface receptor TGR5 and the nuclear receptor FXR. After a meal, approximately 95% of the bile acids are transported from terminal ileum and back to the liver via the portal vein, resulting in postprandial elevations of bile acids in blood. During the digestion of fat, components from the microbiota, including LPS, are thought to reach the circulation where it may lead to inflammatory responses after binding TLR4 immune cells. Both LPS and bile acids are present in blood after a high-fat meal; we therefore wanted to study consequences of a possible interplay between TGR5 and TLR4 in human monocytes.

METHODS

The monocytic cell line U937 stably transfected with the NF-κB reporter plasmid 3x-κB-luc was used as a model system to study the effects of TGR5 and TLR4. Activation of MAP kinases was studied to reveal functional consequences of triggering TGR5 in U937 cells. Effects of TGR5 and TLR4 activation were monitored using NF-κB luciferase assay and by quantification of the pro-inflammatory cytokines IL-6 and IL-8 using ELISA.

RESULTS

In this study, results show that triggering TGR5 with the specific agonist betulinic acid (BA), and the bile acids CDCA or DCA, activated both the main MAP kinases ERK1/2, p38 and JNK, and the NF-κB signaling pathway. We further demonstrated that co-triggering of TLR4 and TGR5 enhanced the activation of NF-κB and the release of inflammatory cytokines in a synergistic manner compared to triggering of TLR4 alone.

CONCLUSIONS

Thus, two different and simultaneous events associated with the digestive process coordinately affect the function of human monocytes and contribute to enhanced inflammation. Because elevated levels of circulatory LPS may contribute to the development of insulin resistance, the results from this study suggest that bile acids through the activation of TGR5 may have a role in the development of insulin resistance as well.

Association between HbA1c variability and mortality in patients with type 2 diabetes

AIMS

We aimed to evaluate the association between HbA1c variability and mortality due to all causes, cancer, and non-cancer in patients with type 2 diabetes independently of mean HbA1c levels.

METHODS

We enrolled 754 patients with type 2 diabetes who first visited our hospital between 1995 and 1996, had been followed for at least 2years, and had undergone four or more HbA1c determinations. Patients were followed through June 2012. The standard deviation (SD) or coefficient of variation (CV) was used as a measure of HbA1c variability. Risk of death was evaluated by multivariate Cox proportional hazard models.

RESULTS

Through June 2012, 63 patients died. Hazard ratios (HRs) for all-cause mortality and non-cancer mortality including cardiovascular diseases (CVD) increased across tertiles of both HbA1cSD and HbA1cCV. HRs for cancer mortality did not increase across tertiles of either HbA1cSD or HbA1cCV. Using a stepwise regression method, both HbA1cSD and HbA1cCV predicted all-cause mortality, especially non-cancer mortality. In contrast, mean HbA1c predicted cancer mortality.

CONCLUSIONS

HbA1c variability is a predictor of all-cause mortality, especially non-cancer mortality including CVD, in patients with type 2 diabetes, independent of mean HbA1c level. In contrast, mean HbA1c, but not HbA1c variability, might predict cancer mortality.

Evidences of +896 A/G TLR4 polymorphism as an indicative of prevalence of complications in T2DM patients

T2DM is today considered as world-wide health problem, with complications responsible of an enhanced mortality and morbidity. Thus, new strategies for its prevention and therapy are necessary. For this reason, the research interest has focused its attention on TLR4 and its polymorphisms, particularly the rs4986790. However, no conclusive findings have been reported until now about the role of this polymorphism in development of T2DM and its complications, even if a recent meta-analysis showed its T2DM association in Caucasians. In this study, we sought to evaluate the weight of rs4986790 polymorphism in the risk of the major T2DM complications, including 367 T2DM patients complicated for the 55.6%. Patients with A/A and A/G TLR4 genotypes showed significant differences in complication's prevalence. In particular, AG carriers had higher risk prevalence for neuropathy (P = 0.026), lower limb arteriopathy (P = 0.013), and the major cardiovascular pathologies (P = 0.017). Their cumulative risk was significant (P = 0.01), with a threefold risk to develop neuropathy, lower limb arteriopathy, and major cardiovascular events in AG cases compared to AA cases. The adjusted OR for the confounding variables was 3.788 (95% CI: 1.642-8.741). Thus, the rs4986790 polymorphism may be an indicative of prevalence of complications in T2DM patients.

Insulin regulates the novel adipokine adipolin/CTRP12: in vivo and ex vivo effects

There has been intense interest in the adipokines of the C1q complement/TNF-related protein (CTRP) superfamily. Adipolin (CTRP12) has been described as a novel adipokine, abundantly expressed in adipose tissue with insulin-sensitising and anti-inflammatory effects. We wanted to investigate the effects of acute and chronic hyperinsulinaemia on circulating adipolin concentrations (ELISA) via a prolonged insulin-glucose infusion in humans. We also examined the effects of insulin and the insulin sensitiser, rosiglitazone, on adipolin concentrations (western blotting) in human adipose tissue explants. We found that hyperinsulinaemic induction in healthy lean human subjects significantly increased circulating levels of adipolin (P<0.05 and P<0.01). Furthermore, in subcutaneous adipose tissue explants, insulin significantly increased adipolin protein expression and secretion (P<0.05 and P<0.01). This effect was attenuated by the phosphatidylinositol 3-kinase inhibitor, LY294002 (P<0.05). Moreover, the insulin-sensitising peroxisome proliferator-activated receptor γ (PPARγ) agonist, rosiglitazone, significantly increased adipolin protein expression and secretion in subcutaneous adipose tissue explants (P<0.05 and P<0.01). This effect was inhibited by the PPARγ antagonist, GW9662 (P<0.05). Our data provide novel insights into adipolin physiology in human subjects.

Diabetes mellitus-associated vascular impairment: novel circulating biomarkers and therapeutic approaches

It is widely accepted that diabetes mellitus (DM) impairs endothelial nitric oxide synthase activity as well as enhances the production of reactive oxygen species, thus resulting in diminished nitric oxide bioavailability and the consequent pro-atherogenetic alterations. Important biomarkers of the vasculature are related to endothelial dysfunction, to inflammatory and coagulation processes, and to oxidative stress in DM. Several therapeutic strategies might exert favorable effects on the vasculature of diabetic patients, such as insulin analogues, antihypertensive agents, statins, and hypoglycemic agents, whereas in spite of the prominent role of oxidative stress in diabetes, antioxidant therapy remains controversial. The use of specific biomarkers related to vascular function could be a useful therapeutic approach in such patients.

Insulin resistance and atherosclerosis: convergence between metabolic pathways and inflammatory nodes

For some time now it has been known that diabetes and atherosclerosis are chronic inflammatory diseases that are closely associated with one another and often develop together. In both there is an increase in tissue-wide inflammation that is exhibited by the infiltration of immune cells into the adipose tissue and the vascular walls respectively. The monocyte/macrophage populations that are recruited in these seemingly different settings also display a high similarity by exhibiting similar phenotypes in both conditions. In the insulin resistant as well as the atherosclerotic setting there is a distinct switch in the macrophage populations present from an anti-inflammatory (M2) population to an inflammatory (M1) population, which releases cytokines and chemotactic factors with the ability to worsen the local environment and thus aggravate the situation by creating a vicious circle. However, although some discoveries suggest that preventing the development of M1 macrophages reduces inflammation and thereby aggravation of these diseases, there are currently no clear-cut opinions on how to achieve a switch from M2 to M1.

Direct effects of locally administered lipopolysaccharide on glucose, lipid, and protein metabolism in the placebo-controlled, bilaterally infused human leg

CONTEXT

Accumulating evidence suggests that chronic exposure to lipopolysaccharide (LPS, endotoxin) may create a constant low-grade inflammation, leading to insulin resistance and diabetes. All previous human studies assessing the metabolic actions of LPS have used systemic administration, making discrimination between direct and indirect effects impossible.

OBJECTIVE

We sought to define the direct, placebo-controlled effects of LPS on insulin resistance and protein and lipid metabolism in the infused human leg without systemic interference from cytokines and stress hormones.

DESIGN

This was a randomized, placebo-controlled, single-blinded study.

PARTICIPANTS AND INTERVENTION

We studied 8 healthy volunteers with bilateral femoral vein and artery catheters during a 3-hour basal and 3-hour hyperinsulinemic-euglycemic clamp period with bilateral muscle biopsies in each period during infusion with saline and LPS.

RESULTS

Overall, LPS perfusion significantly decreased leg glucose uptake, and during the clamp LPS decreased glucose arteriovenous differences (0.65 ± 0.07 mmol/L vs 0.73 ± 0.08 mmol/L). Net palmitate release was increased by LPS, and secondary post hoc testing indicated increased palmitate isotopic dilution, although primary ANOVA tests did not reveal significant dilution. Leg blood flows, phenylalanine, lactate kinetics, cytokines, and intramyocellular insulin signaling were not affected by LPS. LPS thus directly inhibits insulin-stimulated glucose uptake and increases palmitate release in the perfused human leg without detectable effects on amino acid metabolism.

CONCLUSIONS

These data strongly suggest that the primary metabolic effect of LPS is increased lipolysis and muscle insulin resistance, which, together with secondary insulin resistance, caused by systemic cytokine and stress hormone release may lead to overt glucose intolerance and diabetes.

Insulin infusion suppresses while glucose infusion induces Toll-like receptors and high-mobility group-B1 protein expression in mononuclear cells of type 1 diabetes patients

The purpose of this study was to determine whether an insulin infusion exerts an anti-inflammatory effect and whether the infusion of small amounts of glucose results in oxidative and inflammatory stress in patients with type 1 diabetes. Ten patients with type 1 diabetes were infused with either 2 U/h of insulin with 100 ml 5% dextrose/h to or just dextrose (100 ml/h) or physiological saline (100 ml/h) for 4 h after an overnight fast on three separate days. Blood samples were collected at 0, 2, 4, and 6 h. Insulin with glucose infusion led to the maintenance of euglycemia and a significant suppression of reactive oxygen species (ROS) generation, p47(phox) expression, Toll-like receptor (TLR)-4, TLR-2, TLR-1, CD14, high-mobility group-B1 (HMGB1), p38 mitogen-activated protein (MAP) kinase, c-Jun NH2-terminal kinase (JNK)-1, and platelet/endothelial cell adhesion molecule expression and a fall in serum concentrations of C-reactive protein, HMGB1, and rapid upon activation T cell expressed and secreted. Glucose infusion led to an increase in plasma glucose concentration from 115 (fasting) to 215 (at 4 and 6 h) mg/dl and to an increase in ROS generation, the expression of TLR-4, TLR-2, TLR-1, HMGB1, p38 MAP kinase, and JNK-1, and plasma concentrations of HMGB1. While insulin reduces indexes of oxidative and inflammatory stress in patients with type 1 diabetes, even small amounts of glucose (20 g over 4 h) induce oxidative and inflammatory stress. These effects are reflected in TLR, p38 MAP kinase, and HMGB1 expression. The induction of significant oxidative and inflammatory stress by small amounts of glucose in patients with type 1 diabetes may have important pathophysiological and therapeutic implications.

Enhancement of lipopolysaccharide-induced toll-like receptor 2 expression and inflammatory cytokine secretion in HUVECs under high glucose conditions

AIMS

Endothelial inflammatory responses mediated by toll-like receptors (TLRs) play an important role in atherogenesis. We aimed to investigate the exacerbation of an inflammatory response in human umbilical vein endothelial cells (HUVECs) under high glucose conditions.

MAIN METHODS

HUVECs were exposed to normal glucose (5.5 mmol/L) and high glucose (25, 50 mmol/L), alone or with lipopolysaccharide (LPS 0, 10, 100, or 1000 μg/L). Then concentrations of TNF-α and IL-6 in the culture supernatants were determined. The expression of toll-like receptor 2 (TLR2), TLR4 and NF-κB was evaluated by Western blot and RT-PCR analysis.

KEY FINDINGS

Compared with the normal glucose group, exposure of HUVECs to 50 mmol/L of glucose or 1000 μg/L of LPS significantly increased the concentrations of TNF-α and IL-6 in the culture supernatants. Neither 25 mmol/L of glucose nor low concentration of LPS (≤100 μg/L) alone had an effect on TNF-α and IL-6 release, or TLR2 expression, but they stimulated the inflammatory response and TLR2 expression under high glucose conditions (25 mmol/L) in combination. LPS (100 μg/L) did not alter the TLR4 expression in HUVECs under high glucose condition. Co-incubation with glucose and LPS increased the nuclear NF-κB expression in endothelial cells. Both NF-κB inhibitor and ROS scavenger could inhibit the enhancement of LPS-induced TLR2 expression and inflammatory cytokine secretion under high glucose conditions.

SIGNIFICANCE

We show in vitro data on the potential role of high glucose in increasing LPS-induced TLR2 expression and inflammatory cytokine secretion in HUVECs, offering a new insight into the pathophysiological pathways involved in atherosclerosis.

Cardiovascular benefits of exogenous insulin

CONTEXT

Recent studies on mediators of inflammation, experimental models of atherosclerosis, and acute ischemia have identified novel mechanisms through which insulin may exert cardiovascular protective effects. This review aims to summarize current knowledge regarding the cardiovascular, antiinflammatory, and antiatherogenic effects of insulin, and the effect of intensive glycemic control in acute cardiovascular disease.

EVIDENCE ACQUISITION

Publications of interest were identified using preselected MeSH terminology and keywords to search online databases such as PubMed and OVID for the period January 1988 to February 2012. Relevant publications were obtained and reviewed by two independent observers, then evaluated a priori against the following criteria: study quality, main clinical outcomes, and applicability to clinical practice.

EVIDENCE SYNTHESIS

Insulin has been shown to exert vasodilatory, antiinflammatory, and antiatherogenic effects in experimental models, independent of its glucose-lowering effects. Additionally, glucose is known to exert potent proinflammatory, prothrombotic, and proapoptotic effects during myocardial infarct, indicative that hyperglycemia is likely to be injurious to the heart. In this context, through its nonmetabolic and metabolic (glucose-lowering) effects, insulin is likely to be cardioprotective and to improve clinical outcomes in acute myocardial infarction.

CONCLUSIONS

Despite promising experimental data and evidence of benefit from single-center randomized clinical trials, clinical evidence supporting the cardioprotective effects of insulin from a multicenter randomized clinical trial is still lacking. Future prospective studies with insulin infused at adequate concentrations, individually titrated to achieve and maintain euglycemia (blood glucose < 140 mg/dl) and minimize hypoglycemia, are required to investigate the role of insulin in the management of patients with acute cardiovascular disease.

Diacerhein attenuates the inflammatory response and improves survival in a model of severe sepsis

Introduction

Hyperglycemia and insulin resistance have been associated with a worse outcome in sepsis. Although tight glycemic control through insulin therapy has been shown to reduce morbidity and mortality rates, the effect of intensive insulin therapy in patients with severe sepsis is controversial because of the increased risk of serious adverse events related to hypoglycemia. Recently, knowledge about diacerhein, an anthraquinone drug with powerful antiinflammatory properties, revealed that this drug improves insulin sensitivity, mediated by the reversal of chronic subclinical inflammation. The aim of the present study was to evaluate whether the antiinflammatory effects of diacerhein after onset of sepsis-induced glycemic alterations is beneficial and whether the survival rate is prolonged in this situation.

Methods

Diffuse sepsis was induced by cecal ligation and puncture surgery (CLP) in male Wistar rats. Blood glucose and inflammatory cytokine levels were assessed 24 hours after CLP. The effect of diacerhein on survival of septic animals was investigated in parallel with insulin signaling and its modulators in liver, muscle, and adipose tissue.

Results

Here we demonstrated that diacerhein treatment improves survival during peritoneal-induced sepsis and inhibits sepsis-induced insulin resistance by improving insulin signaling via increased insulin-receptor substrate-1-associated phosphatidylinositol 3-kinase activity and Akt phosphorylation. Diacerhein also decreases the activation of endoplasmic reticulum stress signaling that involves upregulation of proinflammatory pathways, such as the I kappa B kinase and c-Jun NH₂-terminal kinase, which blunts insulin-induced insulin signaling in liver, muscle, and adipose tissue. Additionally, our data show that this drug promoted downregulation of proinflammatory signaling cascades that culminate in transcription of immunomodulatory factors such interleukin (IL)-1β, IL-6, and tumor necrosis factor-α.

Conclusions

This study demonstrated that diacerhein treatment increases survival and attenuates the inflammatory response with a significant effect on insulin sensitivity. On the basis of efficacy and safety profile, diacerhein represents a novel antiinflammatory therapy for management of insulin resistance in sepsis and a potential approach for future clinical trials.

Metabolic diseases and pro- and prebiotics: Mechanistic insights

Metabolic diseases, such as obesity and type 2 diabetes, are world-wide health problems. The prevalence of metabolic diseases is associated with dynamic changes in dietary macronutrient intake during the past decades. Based on national statistics and from a public health viewpoint, traditional approaches, such as diet and physical activity, have been unsuccessful in decreasing the prevalence of metabolic diseases. Since the approaches strongly rely on individual’s behavior and motivation, novel science-based strategies should be considered for prevention and therapy for the diseases. Metabolism and immune system are linked. Both overnutrition and infection result in inflammation through nutrient and pathogen sensing systems which recognize compounds with structural similarities. Dietary macronutrients (fats and sugars) can induce inflammation through activation of an innate immune receptor, Toll-like receptor 4 (TLR4). Long-term intake of diets high in fats and meats appear to induce chronic systemic low-grade inflammation, endotoxicity, and metabolic diseases. Recent investigations support the idea of the involvement of intestinal bacteria in host metabolism and preventative and therapeutic potentials of probiotic and prebiotic interventions for metabolic diseases. Specific intestinal bacteria seem to serve as lipopolysaccharide (LPS) sources through LPS and/or bacterial translocation into the circulation due to a vulnerable microbial barrier and increased intestinal permeability and to play a role in systemic inflammation and progression of metabolic diseases. This review focuses on mechanistic links between metabolic diseases (mainly obesity and type 2 diabetes), chronic systemic low-grade inflammation, intestinal environment, and nutrition and prospective views of probiotic and prebiotic interventions for the diseases.

Influence of a high-fat diet on gut microbiota, intestinal permeability and metabolic endotoxaemia

Lipopolysaccharide (LPS) may play an important role in chronic diseases through the activation of inflammatory responses. The type of diet consumed is of major concern for the prevention and treatment of these diseases. Evidence from animal and human studies has shown that LPS can diffuse from the gut to the circulatory system in response to the intake of high amounts of fat. The method by which LPS move into the circulatory system is either through direct diffusion due to intestinal paracellular permeability or through absorption by enterocytes during chylomicron secretion. Considering the impact of metabolic diseases on public health and the association between these diseases and the levels of LPS in the circulatory system, this review will mainly discuss the current knowledge about high-fat diets and subclinical inflammation. It will also describe the new evidence that correlates gut microbiota, intestinal permeability and alkaline phosphatase activity with increased blood LPS levels and the biological effects of this increase, such as insulin resistance. Although the majority of the studies published so far have assessed the effects of dietary fat, additional studies are necessary to deepen the understanding of how the amount, the quality and the structure of the fat may affect endotoxaemia. The potential of food combinations to reduce the negative effects of fat intake should also be considered in future studies. In these studies, the effects of flavonoids, prebiotics and probiotics on endotoxaemia should be investigated. Thus, it is essential to identify dietetic strategies capable of minimising endotoxaemia and its postprandial inflammatory effects.

Redox-regulating role of insulin: the essence of insulin effect

It is well-known that insulin acts as an important hormone, controlling energy metabolism, cellular proliferation and biosynthesis of functional molecules to maintain a biological homeostasis. Over the past few years, intensive insulin therapy has been believed to be benefit for the outcome of diabetic patients, in which the suppression of oxidative stress plays a role. Moreover, insulin is accepted as a key component of glucose-insulin-potassium, a treatment which has been believed to exert significant cardiovascular protective effect via the reduction of oxidative stress. Furthermore, accumulating evidence has suggested that insulin exerts important redox-regulating actions in various insulin-sensitive target organs, implying the systematic antioxidative role of insulin as a hormone. It is time for us to revisit insulin effects, through summarizing and evaluating the novel functions of insulin and their mechanisms. This review focuses on the antioxidative effect of insulin and highlights insulin-induced regulation of various antioxidant enzymes via insulin signaling pathways and the cross talk between key transcription factors, including nuclear factor erythroid 2-related factor 2 (Nrf2) and nuclear factor κB (NF-κB) which are responsible for the transcription of antioxidant enzymes, leading to reduced generation of reactive oxygen species (ROS) and the enhancement of the elimination of ROS.

Diabetes is an inflammatory disease: evidence from traditional Chinese medicines

Diabetes is usually associated with inflammation. Inflammation contributes to the development of diabetes. Traditional Chinese medicines (TCM) play an important role in lowering blood glucose and controlling inflammation. Many studies show that TCM with hypoglycaemic effects, for example Radix Astragali, Radix Rehmanniae, Radix Trichosanthis, Panax Ginseng, Fructus Schisandrae, Radix Ophiopogonis, Rhizoma Anemarrhenae, Radix Puerariae, Fructus Lycii, Poria, Rhizoma Coptidis, Rhizoma Dioscoreae, Rhizoma Polygonati, Radix Salviae Miltiorrhizae, Radix Glycyrrhizae, Semen Trigonellae, Momordica charantia, Allium sativum, Opuntia stricta, Aloe vera, Cortex Cinnamomi, Rhizoma Curcumae Longae, and so on, have nearly independent anti-inflammatory action. Antihyperglycaemic compounds, for example berberine, puerarin, quercetin, ferulic acid, astragaloside IV, curcumin, epigallocatechin gallate, resveratrol, tetrandrine, glycyrrhizin, emodin and baicalin, used in TCM also have anti-inflammatory effects. These studies suggest that TCM might exert hypoglycaemic effects that are partly mediated by the anti-inflammatory mechanisms. However, small amounts of TCM with potent anti-inflammatory action does not have any hypoglycaemic effect. This indirectly indicates that diabetes may be a low-grade inflammatory disease and potent regulation of inflammatory mediators may not be required. Studies of TCM add new evidences, which indicate that diabetes may be an inflammatory disease and slight or moderate inhibition of inflammation might be useful to prevent the development of diabetes. Through this review, we aim to develop more perspectives to indicate that diabetes may be an inflammatory disease and diverse TCM may share a common antidiabetic property: anti-inflammatory action. Further studies should focus on and validate inflammation-regulating targets of TCM that may be involved in inhibiting the development of diabetes.