Reduced tyrosine kinase activity of the insulin receptor in obesity-diabetes. Central role of tumor necrosis factor-alpha

Mechanism by which arylamine N-acetyltransferase 1 ablation causes insulin resistance in mice

Insulin resistance in liver and skeletal muscle are major factors in the pathogenesis of type 2 diabetes; however, the molecular mechanism or mechanisms responsible for this phenomenon have not been established. Recently, an association of a single-nucleotide polymorphism in the human N-acetyltransferase 2 (Nat2) gene with insulin resistance in humans was found. Here, we show that the murine ortholog Nat1 knockout (KO) mice manifested whole-body insulin resistance associated with marked increases in liver and muscle lipid content. Nat1 KO mice also displayed reduced whole-body energy expenditure and reduced mitochondrial activity. Taken together, these studies demonstrate that Nat1 deletion promotes reduced mitochondrial activity and is associated with ectopic lipid-induced liver and muscle insulin resistance.

A single-nucleotide polymorphism in the human arylamine N-acetyltransferase 2 (Nat2) gene has recently been identified as associated with insulin resistance in humans. To understand the cellular and molecular mechanisms by which alterations in Nat2 activity might cause insulin resistance, we examined murine ortholog Nat1 knockout (KO) mice. Nat1 KO mice manifested whole-body insulin resistance, which could be attributed to reduced muscle, liver, and adipose tissue insulin sensitivity. Hepatic and muscle insulin resistance were associated with marked increases in both liver and muscle triglyceride (TAG) and diacylglycerol (DAG) content, which was associated with increased PKCε activation in liver and increased PKCθ activation in skeletal muscle. Nat1 KO mice also displayed reduced whole-body energy expenditure and reduced mitochondrial oxygen consumption in white adipose tissue, brown adipose tissue, and hepatocytes. Taken together, these studies demonstrate that Nat1 deletion promotes reduced mitochondrial activity and is associated with ectopic lipid-induced insulin resistance. These results provide a potential genetic link among mitochondrial dysfunction with increased ectopic lipid deposition, insulin resistance, and type 2 diabetes.

Severe Hypoglycemia Caused by Lenalidomide

Lenalidomide is commonly used for multiple myeloma as either induction or maintenance therapy. The agent is associated with a host of adverse effects, but hypoglycemia has only been reported in one phase I trial in patients with solid tumors. We describe a 74-year-old woman who experienced grade 3 hypoglycemia (blood glucose level 35 mg/dl) likely related to lenalidomide. Her medical history was significant for refractory myeloma and type 2 diabetes mellitus. Lenalidomide was started as maintenance therapy following autologous bone marrow transplantation. Approximately 3 years later, she developed refractory hypoglycemia necessitating hospital admission despite stopping antihyperglycemic agents 4 weeks prior to admission. Lenalidomide was withheld during her admission and restarted 2 days prior to discharge. Work-up for causes of persistent hypoglycemia was negative, and her glucose levels improved over her 26-day hospitalization. She was readmitted approximately one month later for hypoglycemia, and lenalidomide was permanently discontinued. Again, work-up for causes of hypoglycemia was negative, and her glucose levels stabilized over her hospitalization. After discontinuation of lenalidomide, hypoglycemia did not recur, and within 1 year the patient required reinitiation of antihyperglycemic medications to control her glucose levels. Given the resolution of hypoglycemia with lenalidomide discontinuation and return of hyperglycemia after restarting the agent, it is likely that lenalidomide was the cause of the patient's hypoglycemia. Use of the Naranjo adverse drug reaction probability scale indicated a definite relationship (score of 9) between the patient's development of grade 3 hypoglycemia and lenalidomide therapy. Although this adverse drug reaction had been previously reported with lenalidomide during phase I trials in patients with solid tumors, only grade 1 or 2 hypoglycemia was reported in three patients. To our knowledge, this is the first reported case of grade 3 hypoglycemia caused by lenalidomide.

The effect of tumor necrosis factor inhibitor therapy on the incidence of myocardial infarction in patients with psoriasis: a retrospective study

BACKGROUND

Psoriasis has been shown to be associated with increased incidence of myocardial infarction (MI). The data on the effect of tumor necrosis factor (TNF) inhibitors on MI in psoriasis are scarce.

OBJECTIVE

To evaluate the effect of TNF inhibitors on the risk of MI in psoriasis patients compared with methotrexate (MTX) and topical agents.

METHODS

Data were obtained from the Electronic Health Records database of Farwaniya Hospital from psoriasis patients seen from January 2008 to December 2014. Patients were categorized into TNF inhibitor, MTX and topical cohorts.

RESULTS

The study included 4762 psoriasis patients. Both TNF inhibitor and MTX cohorts showed a statistically lower rate of MI compared with topical cohort. However, there was no statistically significant difference in MI rate between TNF inhibitor and MTX cohorts (P = .32). The probability of MI was lower in TNF inhibitor responders compared with non-responders (p = .001).

CONCLUSIONS

The use of TNF inhibitors in psoriasis showed a significant reduction in the risk of MI compared with topical agents and a non-significant reduction compared with MTX. Responders to TNF inhibitor therapy showed a reduction in MI rate compared with non-responders.

Meta-inflammation and cardiometabolic disease in obesity: Can heat therapy help?

Obesity and associated metabolic dysfunction have reached epidemic proportions worldwide. The current theory linking metabolic disease and obesity involves ischemic adipose tissue initiating an inflammatory cascade that results in systemic insulin resistance and may eventually lead to type II diabetes mellitus. Diabetes and associated metabolic dysfunction increase the risk of developing cardiovascular disease and fatal cardiovascular events. By targeting key steps in this process, ischemia and inflammation, this cascade may be prevented or reversed and thus metabolic and cardiovascular health may be preserved in obesity. Regular heat exposure (termed ‘heat therapy’) offers potential to improve cardiometabolic health in obese individuals through a variety of mechanisms that include but are not limited to heat shock proteins, hypoxia-inducible factor 1α, and hemodynamic effects. The purpose of this review is to highlight the cardiometabolic decline in obese individuals stemming from adipose tissue dysfunction, and examine the ways in which heat therapy and associated cellular and systemic adaptations can intersect with this decline in function to improve or restore cardiovascular and metabolic health.

Fasting levels of insulin and amylin after acute pancreatitis are associated with pro-inflammatory cytokines

BACKGROUND

The prevalence of metabolic diseases continues to rise worldwide, with a growing recognition of metabolic dysregulation after acute inflammatory diseases such as acute pancreatitis (AP). Adipokines and cytokines play an important role in metabolism and the course of AP, but there is a paucity of research investigating their relationship with pancreatic hormones after AP. This study aimed to explore associations between pancreatic hormones and adipokines as well as cytokines to provide insights into the pathophysiology of altered pancreatic hormone secretion following AP [corrected].

METHODS

A total of 83 patients previously diagnosed with AP and no prior diabetes or pre-diabetes were recruited into this cross-sectional follow up study. Fasting venous blood samples were collected to analyse a panel of pancreatic hormones and derivatives (amylin, C-peptide, glucagon, insulin, pancreatic polypeptide, somatostatin), adipokines (adiponectin, leptin, retinol binding protein-4, and resistin), and cytokines (interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), and tumour necrosis factor-α (TNF-α)). Linear regression analyses were used, and potential confounders were adjusted for in multivariate analyses.

RESULTS

Insulin was significantly associated with IL-6 in both unadjusted and adjusted models (p = .029 and p = .040, respectively). Amylin was significantly associated with MCP-1 in the unadjusted model (p = .046), and TNF-α in unadjusted and adjusted models (p = .025 and p = .027, respectively).

CONCLUSIONS

Insulin and amylin have a strong positive association with pro-inflammatory cytokines in patients following an episode of AP. These associations have possible relevance in the development of diabetes associated with diseases of the exocrine pancreas, providing the opportunity to develop novel treatment paradigms.

Association between Diastolic Dysfunction with Inflammation and Oxidative Stress in Females ob/ob Mice

Objective: To evaluate autonomic and cardiovascular function, as well as inflammatory and oxidative stress markers in ob/ob female mice.

Methods: Metabolic parameters, cardiac function, arterial pressure (AP), autonomic, hormonal, inflammatory, and oxidative stress markers were evaluated in 12-weeks female wild-type (WT group) and ob/ob mice (OB group).

Results: OB animals showed increased body weight, blood glucose, and triglyceride levels, along with glucose intolerance, when compared to WT animals. Ejection fraction (EF) and AP were similar between groups; however, the OB group presented diastolic dysfunction, as well as an impairment on myocardial performance index. Moreover, the OB group exhibited important autonomic dysfunction and baroreflex sensitivity impairment, when compared to WT group. OB group showed increased Angiotensin II levels in heart and renal tissues; decreased adiponectin and increased inflammatory markers in adipose tissue and spleen. Additionally, OB mice presented a higher damage to proteins and lipoperoxidation and lower activity of antioxidant enzymes in kidney and heart. Correlations were found between autonomic dysfunction with angiotensin II and inflammatory mediators, as well as between inflammation and oxidative stress.

Conclusions: Our results showed that female adult ob/ob mice presented discrete diastolic dysfunction accompanied by autonomic disorder, which is associated with inflammation and oxidative stress in these animals.

Cell biology of fat storage

The worldwide epidemic of obesity and type 2 diabetes has greatly increased interest in the biology and physiology of adipose tissues. Adipose (fat) cells are specialized for the storage of energy in the form of triglycerides, but research in the last few decades has shown that fat cells also play a critical role in sensing and responding to changes in systemic energy balance. White fat cells secrete important hormone-like molecules such as leptin, adiponectin, and adipsin to influence processes such as food intake, insulin sensitivity, and insulin secretion. Brown fat, on the other hand, dissipates chemical energy in the form of heat, thereby defending against hypothermia, obesity, and diabetes. It is now appreciated that there are two distinct types of thermogenic fat cells, termed brown and beige adipocytes. In addition to these distinct properties of fat cells, adipocytes exist within adipose tissue, where they are in dynamic communication with immune cells and closely influenced by innervation and blood supply. This review is intended to serve as an introduction to adipose cell biology and to familiarize the reader with how these cell types play a role in metabolic disease and, perhaps, as targets for therapeutic development.

Metabolic Manifestations of Hepatitis C Virus: Diabetes Mellitus, Dyslipidemia

Metabolic disorders are common in patients with chronic hepatitis C virus (HCV) infection. Epidemiologic and clinical data indicate an overprevalence of lipids abnormalite, steatosis, insuline resistance (IR) and diabetes mellitus in HCV patients, suggesting that HCV itself may interact with glucido-lipidic metabolism. HCV interacts with the host lipid metabolism by several mechanisms leading to hepatic steatosis and hypolipidemia which are reversible after viral eradication. Liver and peripheral IR are HCV genotype/viral load dependent and improved after viral eradication. This article examines examine the relationship between HCV, lipid abnormalities, steatosis, IR, and diabetes and the pathogenic mechanisms accounting for these events in HCV-infected patients.

The change of serum tumor necrosis factor alpha in patients with type 1 diabetes mellitus: A systematic review and meta-analysis

OBJECTIVE

The aim of this study was used meta-analysis to investigate changes of serum tumor necrosis factor-alpha (TNF-α) in patients with type 1 diabetes mellitus (T1DM).

METHODS

Relevant literatures were identified from PubMed, Cochrane Library, CNKI, WanFang and Chinese-Cqvip databases (published from January 1, 1999 to September 30, 2016). Eligible reports were included for pooled analysis of serum TNF-α level and subgroup analysis was performed in relation with age, disease duration and ethnicity.

RESULTS

A total of 23 articles (1631 T1DM cases, 1429 healthy controls) were included for this meta-analysis. Compared with the controls, the patients had significantly increased serum TNF-α level (P < 0.001). Similar results were also found among all subgroup analysis of different age, disease duration and ethnicity (with the exception of Asian) (all P < 0.05). Regression analysis indicated that age (P = 0.680), disease duration (P = 0.957), and ethnicity (P = 0.526) of patients were not significant impact factors for the high heterogeneity. The results were stable according to the sensitivity analysis and no publication bias existed in this meta-analysis.

CONCLUSIONS

Serum TNF-α level in T1DM patients has significantly elevated among all age, disease duration and ethnicity groups.

ADP-ribosylation factor-like GTPase 15 enhances insulin-induced AKT phosphorylation in the IR/IRS1/AKT pathway by interacting with ASAP2 and regulating PDPK1 activity

Decreased phosphorylation in the insulin signalling pathway is a hallmark of insulin resistance. The causes of this phenomenon are complicated and multifactorial. Recently, genomic analyses have identified ARL15 as a new candidate gene related to diabetes. However, the ARL15 protein function remains unclear. Here, we show that ARL15 is upregulated by insulin stimulation. This effect was impaired in insulin-resistant pathophysiology in TNF-α-treated C2C12 myotubes and in the skeletal muscles of leptin knockout mice. In addition, ARL15 localized to the cytoplasm in the resting state and accumulated in the Golgi apparatus around the nucleus upon insulin stimulation. ARL15 overexpression can enhance the phosphorylation of the key insulin signalling pathway molecules IR, IRS1 and AKT in C2C12 myotubes. Moreover, ARL15 knockdown can also specifically inhibit the phosphorylation of PDPK1 Ser241, thereby reducing PDPK1 activity and its downstream phosphorylation of AKT Thr308. Co-immunoprecipitation assays identified ASAP2 as an ARL15-interacting protein. In conclusion, we have identified that ARL15 acts as an insulin-sensitizing effector molecule to upregulate the phosphorylation of members of the canonical IR/IRS1/PDPK1/AKT insulin pathway by interacting with its GAP ASAP2 and activating PDPK1. This research may provide new insights into GTPase-mediated insulin signalling regulation and facilitate the development of new pharmacotherapeutic targets for insulin sensitization.

Cooling down inflammation in type 2 diabetes: how strong is the evidence for cardiometabolic benefit?

Chronic inflammation is supposed to be an important mediator of cardiometabolic dysfunctions seen in type 2 diabetes. In this mini-review, we collected evidence (PubMed) from randomized controlled trials (through March 2016) evaluating the effect of anti-inflammatory drugs on indices of glycemic control and/or cardiovascular events in people with type 2 diabetes. Within the last 25 years, many anti-inflammatory drugs have been tested in type 2 diabetes, including hydroxychloroquine, anti-tumor necrosis factor therapies (etanercept and infliximab), salsalate, interleukin-1 antagonists (anakinra, canakinumab, gevokizumab, LY2189102), and CC-R2 antagonists. Despite being promising, the observed effects on HbA1c or glucose control remain rather modest in most clinical trials, especially with the new drugs. There are many trials underway with anti-inflammatory agents to see whether patients with cardiovascular diseases and/or type 2 diabetes may have clinical benefit from marked reductions in circulating inflammatory markers. Until now, a large trial with losmapimod (a p38 inhibitor) among patients with acute myocardial infarction, including one/third of diabetic patients, showed no reduction in the risk of major ischemic cardiovascular events. Further evidence is warranted in support of the concept that targeting inflammation pathways may ameliorate glycemic control and also reduce cardiovascular complications in type 2 diabetes.

Exercise Training Attenuates the Dysregulated Expression of Adipokines and Oxidative Stress in White Adipose Tissue

Obesity-induced inflammatory changes in white adipose tissue (WAT), which caused dysregulated expression of inflammation-related adipokines involving tumor necrosis factor-α and monocyte chemoattractant protein-1, contribute to the development of insulin resistance. Moreover, current literature reports state that WAT generates reactive oxygen species (ROS), and the enhanced production of ROS in obese WAT has been closely associated with the dysregulated expression of adipokines in WAT. Therefore, the reduction in excess WAT and oxidative stress that results from obesity is thought to be one of the important strategies in preventing and improving lifestyle-related diseases. Exercise training (TR) not only brings about a decrease in WAT mass but also attenuates obesity-induced dysregulated expression of the adipokines in WAT. Furthermore, some reports indicate that TR affects the generation of oxidative stress in WAT. This review outlines the impact of TR on the expression of inflammation-related adipokines and oxidative stress in WAT.

NAFLD and diabetes mellitus

The liver constitutes a key organ in systemic metabolism, contributing substantially to the development of insulin resistance and type 2 diabetes mellitus (T2DM). The mechanisms underlying these processes are not entirely understood, but involve hepatic fat accumulation, alterations of energy metabolism and inflammatory signals derived from various cell types including immune cells. Lipotoxins, mitochondrial function, cytokines and adipocytokines have been proposed to play a major part in both NAFLD and T2DM. Patients with NAFLD are commonly insulin resistant. On the other hand, a large number of patients with T2DM develop NAFLD with its inflammatory complication, NASH. The high incidence of NASH in patients with T2DM leads to further complications, such as liver cirrhosis and hepatocellular carcinoma, which are increasingly recognized. Therapeutic concepts such as thiazolidinediones (glitazones) for treating T2DM also show some efficacy in the treatment of NASH. This Review will describe the multifaceted and complex interactions between the liver and T2DM.

Upregulation of Tumor Necrosis Factor-α-Induced Protein 8-Like 2 mRNA Is Negatively Correlated with Serum Concentrations of Tumor Necrosis Factor-α and Interleukin 6 in Type 2 Diabetes Mellitus

BACKGROUND

Tumor necrosis factor-α-induced protein 8-like 2 (TIPE2 or TNFAIP8L2) is a negative regulator of natural and adaptive immunity. The role of TIPE2 in type 2 diabetes mellitus (T2DM) remains unknown, although TIPE2 plays key roles in preserving inflammatory homeostasis.

METHODS

TIPE2 expression was measured by Western blotting and real-time polymerase chain reaction (RT-PCR) in peripheral blood mononuclear cells (PBMCs) isolated from T2DM patients and healthy controls, and tumor necrosis factor-α (TNF-α), high-sensitivity C-reactive protein (hsCRP), interleukin 6 (IL-6), and other related biometabolic parameters were detected using a nephelometer or by ELISA. Differentiated THP-1 cells were exposed to siTIPE2 and TIPE2 adenovirus.

RESULTS

TIPE2 was significantly increased in PBMCs from T2DM patients compared with those from healthy controls and was negatively correlated with serum TNF-α, IL-6, and hsCRP concentrations but positively correlated with HbA1c and LDL-C in T2DM patients. High glucose treatment (50 mmol/L) can upregulate the expression of TIPE2 and cytokine secretion in differentiated THP-1 cells. siTIPE2 infection exacerbated the increased TNF-α and IL-6 concentrations in differentiated THP-1 cells under high glucose conditions (50 mmol/L), while infection with TIPE2 adenovirus reversed the increased TNF-α concentration.

CONCLUSIONS

The present study indicates that TIPE2 may participate in T2DM by regulating TNF-α production.

High Serum Tumor Necrosis Factor-Alpha Levels in Women with Polycystic Ovary Syndrome: A Meta-Analysis

The objective of the study is to assess the TNF-α levels in PCOS patients and healthy controls. A comprehensive electronic search in Medline, Embase, and the Cochrane Library database was conducted up to July 2016. Random-effects model was used to estimate the standardized mean differences (SMDs) with 95% confidence intervals (CIs). Twenty-nine studies with a total of 1960 participants (1046 PCOS patients and 914 controls) were included in this meta-analysis. The TNF-α levels in PCOS patients were significantly higher than those in controls (random-effects, SMD = 0.60, 95% CI = 0.28-0.92, P<0.001). With regard to the subgroup analyses stratified by ethnicity, study quality, methods, and BMI, significantly high TNF-α levels were found in patients with PCOS in almost all of these subgroups. In the subgroup stratified by HOMA-IR ratio and T ratio, significant differences were only observed in the subgroups with HOMA-IR ratio of >1.72(SMD = 0.967, 95% CI = 0.103-1.831, P = 0.028, I2 = 93.5%) and T ratio>2.10 (SMD = 1.420, 95% CI = 0.429-2.411, P = 0.005, I2 = 96.1%). By meta-regression it was suggested that ethnicity might contribute little to the heterogeneity between the included studies. Through cumulative meta-analysis and sensitivity analysis it was supposed that the higher TNF-α levels of PCOS patients compared to healthy controls was stable and reliable. This meta-analysis suggests that the circulating TNF-α levels in women with PCOS are significantly higher than those in healthy controls. It may be involved in promoting insulin resistance and androgen excess of PCOS.

Commentary: Periodontal Treatment and Inflammation in Diabetes: Association or Causation?

The causal effect of periodontal treatment on systemic outcomes is unclear because even randomized controlled trials (RCTs) have conflicting results. Two models are proposed to explain the apparently conflicting findings from RCTs evaluating the effect of periodontal treatment on inflammation and systemic outcomes among individuals with type 2 diabetes.

Differential Role of Adipose Tissues in Obesity and Related Metabolic and Vascular Complications

This review focuses on the contribution of white, brown, and perivascular adipose tissues to the pathophysiology of obesity and its associated metabolic and vascular complications. Weight gain in obesity generates excess of fat, usually visceral fat, and activates the inflammatory response in the adipocytes and then in other tissues such as liver. Therefore, low systemic inflammation responsible for insulin resistance contributes to atherosclerotic process. Furthermore, an inverse relationship between body mass index and brown adipose tissue activity has been described. For these reasons, in recent years, in order to combat obesity and its related complications, as a complement to conventional treatments, a new insight is focusing on the role of the thermogenic function of brown and perivascular adipose tissues as a promising therapy in humans. These lines of knowledge are focused on the design of new drugs, or other approaches, in order to increase the mass and/or activity of brown adipose tissue or the browning process of beige cells from white adipose tissue. These new treatments may contribute not only to reduce obesity but also to prevent highly prevalent complications such as type 2 diabetes and other vascular alterations, such as hypertension or atherosclerosis.

Perpetuating effects of androgen deficiency on insulin resistance

Background/Objectives

Androgen deprivation therapy (ADT) is commonly used for treatment of prostate cancer, but is associated with side effects such as sarcopenia and insulin resistance. The role of lifestyle factors such as diet and exercise on insulin sensitivity and body composition in testosterone-deficient males is poorly understood. The aim of the present study was to examine the relationships between androgen status, diet, and insulin sensitivity.

Subjects/Methods

Middle-aged (11–12-yo) intact and orchidectomized male rhesus macaques were maintained for two months on a standard chow diet, and then exposed for six months to a Western-style, high-fat/calorie-dense diet (WSD) followed by four months of caloric restriction (CR). Body composition, insulin sensitivity, physical activity, serum cytokine levels, and adipose biopsies were evaluated before and after each dietary intervention.

Results

Both intact and orchidectomized animals gained similar proportions of body fat, developed visceral and subcutaneous adipocyte hypertrophy, and became insulin resistant in response to the WSD. CR reduced body fat in both groups, but reversed insulin resistance only in intact animals. Orchidectomized animals displayed progressive sarcopenia, which persisted after the switch to CR. Androgen deficiency was associated with increased levels of interleukin-6 and macrophage-derived chemokine (CCL22), both of which were elevated during CR. Physical activity levels showed a negative correlation with body fat and insulin sensitivity.

Conclusion

Androgen deficiency exacerbated the negative metabolic side effects of the WSD, such that CR alone was not sufficient to improve altered insulin sensitivity, suggesting that ADT patients will require additional interventions to reverse insulin resistance and sarcopenia.

Therapeutic applications of conditioned medium from adipose tissue

For the past number of decades, adipose tissue has attracted significant interest due to its complicated composition and versatile functions. Adipose tissue is no longer considered to be just an energy-storing fat pad, but is also a key ring player in interaction networks between various organs and tissues. A wide range of factors released by adipose tissue are responsible for regulation of adipose tissue and other distant target tissues and cells, such as kidneys, skeletal muscle, the cardiovascular system and the immune system, in an auto-/paracrine manner. A mixture of bioactive molecules makes up the conditioned medium of adipose tissue. The beneficial role played by these bioactive molecules in angiogenesis, wound healing, tissue regeneration and immunomodulation has been demonstrated by various studies. Study of this conditioned medium helps deepen our understanding of underlying mechanisms and broadens the potential for therapeutic applications. In this review, we have aimed to improve fundamental understanding of conditioned medium from adipose tissue and to summarize recent efforts to study its therapeutic applications.

Excessive training impairs the insulin signal transduction in mice skeletal muscles

The main aim of this investigation was to verify the effects of overtraining (OT) on the insulin and inflammatory signaling pathways in mice skeletal muscles. Rodents were divided into control (CT), overtrained by downhill running (OTR/down), overtrained by uphill running (OTR/up), and overtrained by running without inclination (OTR) groups. Rotarod, incremental load, exhaustive, and grip force tests were used to evaluate performance. Thirty-six hours after the grip force test, the extensor digitorum longus (EDL) and soleus were extracted for subsequent protein analyses. The three OT protocols led to similar responses of all performance evaluation tests. The phosphorylation of insulin receptor beta (pIRβ; Tyr), protein kinase B (pAkt; Ser473), and the protein levels of plasma membrane glucose transporter-4 (GLUT4) were lower in the EDL and soleus after the OTR/down protocol and in the soleus after the OTR/up and OTR protocols. While the pIRβ was lower after the OTR/up and OTR protocols, the pAkt was higher after the OTR/up in the EDL. The phosphorylation of IκB kinase alpha and beta (pIKKα/β; Ser180/181), stress-activated protein kinases/Jun amino-terminal kinases (pSAPK-JNK; Thr183/Tyr185), factor nuclear kappa B (pNFκB p65; Ser536), and insulin receptor substrate 1 (pIRS1; Ser307) were higher after the OTR/down protocol, but were not altered after the two other OT protocols. In summary, these data suggest that OT may lead to skeletal muscle insulin signaling pathway impairment, regardless of the predominance of eccentric contractions, although the insulin signal pathway impairment induced in OTR/up and OTR appeared to be muscle fiber-type specific.

MECHANISMS IN ENDOCRINOLOGY: Metabolic and inflammatory pathways on the pathogenesis of type 2 diabetes

Obesity is the main risk factor for type 2 diabetes (T2D). Studies performed over the last 20 years have identified inflammation as the most important link between these two diseases. During the development of obesity, there is activation of subclinical inflammatory activity in tissues involved in metabolism and energy homeostasis. Intracellular serine/threonine kinases activated in response to inflammatory factors can catalyse the inhibitory phosphorylation of key proteins of the insulin-signalling pathway, leading to insulin resistance. Moreover, during the progression of obesity and insulin resistance, the pancreatic islets are also affected by inflammation, contributing to β-cell failure and leading to the onset of T2D. In this review, we will present the main mechanisms involved in the activation of obesity-associated metabolic inflammation and discuss potential therapeutic opportunities that can be developed to treat obesity-associated metabolic diseases.

Effects of Allium hookeri root water extracts on inhibition of adipogenesis and GLUT-4 expression in 3T3-L1 adipocytes

Anti-adipogenic and antidiabetic activities of Allium hookeri root water extracts (ARW) were assessed. Oil Red O staining showed that treatment with ARW caused a dose-dependent reduction in lipid accumulation. ARW was also involved in adipocyte lipolysis via LPL activity, and in the concentration of glycerol in a culture medium. On the basis of the concentration of adipokines following ARW treatment, ARW appeared to inhibit expression of PPAR-γ, to reduce concentrations of leptin and resistin, to increase the concentration of adiponectin, and to inhibit lipid accumulation. ARW modulated adipokine expression associated with insulin resistance and sensitivity. 3T3-L1 adipocytes treated with ARW showed increased GLUT-4 expression with increased glucose uptake into adipocytes. ARW showed effectiveness for improvement of diabetic conditions.

Metabolic Inflammation-Differential Modulation by Dietary Constituents

Obesity arises from a sustained positive energy balance which triggers a pro-inflammatory response, a key contributor to metabolic diseases such as T2D. Recent studies, focused on the emerging area of metabolic-inflammation, highlight that specific metabolites can modulate the functional nature and inflammatory phenotype of immune cells. In obesity, expanding adipose tissue attracts immune cells, creating an inflammatory environment within this fatty acid storage organ. Resident immune cells undergo both a pro-inflammatory and metabolic switch in their function. Inflammatory mediators, such as TNF-α and IL-1β, are induced by saturated fatty acids and disrupt insulin signaling. Conversely, monounsaturated and polyunsaturated fatty acids do not interrupt metabolism and inflammation to the same extent. AMPK links inflammation, metabolism and T2D, with roles to play in all and is influenced negatively by obesity. Lipid spillover results in hepatic lipotoxicity and steatosis. Also in skeletal muscle, excessive FFA can impede insulin's action and promote inflammation. Ectopic fat can also affect pancreatic β-cell function, thereby contributing to insulin resistance. Therapeutics, lifestyle changes, supplements and dietary manipulation are all possible avenues to combat metabolic inflammation and the subsequent insulin resistant state which will be explored in the current review.

The Drosophila TNF Eiger Is an Adipokine that Acts on Insulin-Producing Cells to Mediate Nutrient Response

Adaptation of organisms to ever-changing nutritional environments relies on sensor tissues and systemic signals. Identification of these signals would help understand the physiological crosstalk between organs contributing to growth and metabolic homeostasis. Here we show that Eiger, the Drosophila TNF-α, is a metabolic hormone that mediates nutrient response by remotely acting on insulin-producing cells (IPCs). In the condition of nutrient shortage, a metalloprotease of the TNF-α converting enzyme (TACE) family is active in fat body (adipose-like) cells, allowing the cleavage and release of adipose Eiger in the hemolymph. In the brain IPCs, Eiger activates its receptor Grindelwald, leading to JNK-dependent inhibition of insulin production. Therefore, we have identified a humoral connexion between the fat body and the brain insulin-producing cells relying on TNF-α that mediates adaptive response to nutrient deprivation.

Effect of Long-Term Periodontal Care on Hemoglobin A1c in Type 2 Diabetes

This was a prospective cohort study evaluating 126,805 individuals with diabetes and periodontal disease receiving care at all Veterans Administration medical centers and clinics in the United States from 2005 through 2012. The exposures were periodontal treatment at baseline (PT0) and at follow-up (PT2). The outcomes were change in HbA1c following initial treatment (ΔHbA1c1) and follow-up treatment (ΔHbA1c2), and diabetes control was defined as HbA1c at <7% and <9% following initial and follow-up treatment, respectively. Marginal structural models were used to account for potential confounding and selection bias. The objective was to evaluate the impact of long-term treatment of periodontal disease on glycemic control among individuals with type 2 diabetes. Participants were 64 y old on average, 97% were men, and 71% were white. At baseline, the average diabetes duration was 4 y, 12% of participants were receiving insulin, and 60% had HbA1c <7%. After an average 1.7 y of follow-up, the mean HbA1c increased from 7.03% to 7.21%. About 29.4% of participants attended their periodontal maintenance visit following baseline. Periodontal treatment at baseline and follow-up reduced HbA1c by -0.02% and -0.074%, respectively. Treatment at follow-up increased the likelihood of individuals achieving diabetes control by 5% and 3% at the HbA1c <7% and HbA1c <9% thresholds, respectively, and was observed even among never smokers. HbA1c reduction after periodontal treatment at follow-up was greater (ΔHbA1c2 = -0.25%) among individuals with higher baseline HbA1c. Long-term periodontal care provided in a clinical setting improved long-term glycemic control among individuals with type 2 diabetes and periodontal disease.

Silencing CCR2 in Macrophages Alleviates Adipose Tissue Inflammation and the Associated Metabolic Syndrome in Dietary Obese Mice

Adipose tissue macrophage (ATM)-mediated inflammation is a key feature contributing to the adverse metabolic outcomes of dietary obesity. Recruitment of macrophages to obese adipose tissues (AT) can occur through the engagement of CCR2, the receptor for MCP-1 (monocyte chemoattractant protein-1), which is expressed on peripheral monocytes/macrophages. Here, we show that i.p. administration of a rabies virus glycoprotein-derived acetylcholine receptor-binding peptide effectively delivers complexed siRNA into peritoneal macrophages and ATMs in a mouse model of high-fat diet-induced obesity. Treatment with siRNA against CCR2 inhibited macrophage infiltration and accumulation in AT and, therefore, proinflammatory cytokines produced by macrophages. Consequently, the treatment significantly improved glucose tolerance and insulin sensitivity profiles, and also alleviated the associated symptoms of hepatic steatosis and reduced hepatic triglyceride production. These results demonstrate that disruption of macrophage chemotaxis to the AT through cell-targeted gene knockdown strategies can provide a therapeutic intervention for obesity-related metabolic diseases. The study also highlights a siRNA delivery approach for targeting specific monocyte subsets that contribute to obesity-associated inflammation without affecting the function of other tissue-resident macrophages that are essential for host homeostasis and survival.

Targeting inflammation in the prevention of cardiovascular disease in patients with inflammatory arthritis

Patients with inflammatory arthritis have increased risk of cardiovascular diseases (CVDs) compared with the general population. Subclinical carotid atherosclerosis and increased arterial stiffness are also common in these patients, which may serve as surrogate end points for cardiovascular (CV) events in clinical trials. Although exact mechanisms are still unclear, persistent systemic inflammation in patients with inflammatory arthritis may contribute to the development of CVD. Dysregulated innate immunity pathways in these patients may also play a role in accelerating atherosclerosis. During the last decade, effective suppression of inflammation by biological disease-modifying antirheumatic drugs has improved the disease outcome dramatically in patients with inflammatory arthritis. Growing evidence suggests that antitumor necrosis factor (TNF) therapy may prevent CVD in patients with rheumatoid arthritis. Nonetheless, data on non-TNF biologics are limited. Whether anti-TNF therapy may prevent CVD in patients with spondyloarthritis also remained unclear. In this review, we summarized the effect of both anti-TNF and non-TNF biologics on the CV system, including traditional CVD risk factors, endothelial function, arterial stiffness, subclinical atherosclerosis, and clinical CVD in patients with inflammatory arthritis.

Molecular and cellular mechanisms linking inflammation to insulin resistance and β-cell dysfunction

Obesity is a major public health problem worldwide, and it is associated with an increased risk of developing type 2 diabetes. It is now commonly accepted that chronic inflammation associated with obesity induces insulin resistance and β-cell dysfunction in diabetic patients. Obesity-associated inflammation is characterized by increased abundance of macrophages and enhanced production of inflammatory cytokines in adipose tissue. Adipose tissue macrophages are suggested to be the major source of local and systemic inflammatory mediators such as tumor necrosis factor α, interleukin (IL)-1β, and IL-6. These cytokines induce insulin resistance in insulin target tissues by activating the suppressors of cytokine signaling proteins, several kinases such as c-Jun N-terminal kinase, IκB kinase β, and protein kinase C, inducible nitric oxide synthase, extracellular signal-regulated kinase, and protein tyrosine phosphatases such as protein tyrosine phosphatase 1B. These activated factors impair the insulin signaling at the insulin receptor and the insulin receptor substrates levels. The same process most likely occurs in the pancreas as it contains a pool of tissue-resident macrophages. High concentrations of glucose or palmitate via the chemokine production promote further immune cell migration and infiltration into the islets. These events ultimately induce inflammatory responses leading to the apoptosis of the pancreatic β cells. In this review, the cellular and molecular players that participate in the regulation of obesity-induced inflammation are discussed, with particular attention being placed on the roles of the molecular players linking inflammation to insulin resistance and β-cell dysfunction.

Effects of high glucose on caveolin-1 and insulin signaling in 3T3-L1 adipocytes

Adipocytes exposed to high glucose concentrations exhibit impaired metabolic function, including an increase of oxidative and proinflammatory factors that might favor the development of insulin resistance. Caveolin-1 (Cav-1) is a key mediator of the insulin transduction pathway whose expression is significantly enhanced during adipocyte differentiation. In this work, we studied the effects of high glucose concentration on the regulation of Cav-1 expression and activation and its relation to the insulin signaling pathway during the adipogenic process and in long-term differentiated adipocytes. Both, long-term high glucose exposure during adipogenesis and short-term glucose incubation of mature adipocytes, promoted triglyceride accumulation in 3T3-L1 cells. The short-term exposure of mature adipocytes to high glucose significantly reduced the sensitivity to insulin of Cav-1, insulin receptor (IR) and potein kinase B (AKT-2) phosphorylation, as well as insulin-induced deoxyglucose uptake. Adipocytes differentiated in the presence of high glucose lost Cav-1 and IR response to insulin-stimulated phosphorylation, but maintained the insulin sensitivity of AKT-2 phosphorylation and deoxyglucose uptake. Although long-term high glucose exposure increased DNA methylation in Cav-1 promoter, Cav-1 expression was not affected. Moreover, these cells showed an increase of Cav-1, IR and AKT-2 protein content, pointing to an adaptive response induced by the long-term high glucose exposure.

Molecular aspects of glucose homeostasis in skeletal muscle--A focus on the molecular mechanisms of insulin resistance

Among all the varied actions of insulin, regulation of glucose homeostasis is the most critical and intensively studied. With the availability of glucose from nutrient metabolism, insulin action in muscle results in increased glucose disposal via uptake from the circulation and storage of excess, thereby maintaining euglycemia. This major action of insulin is executed by redistribution of the glucose transporter protein, GLUT4 from intracellular storage sites to the plasma membrane and storage of glucose in the form of glycogen which also involves modulation of actin dynamics that govern trafficking of all the signal proteins of insulin signal transduction. The cellular mechanisms responsible for these trafficking events and the defects associated with insulin resistance are largely enigmatic, and this review provides a consolidated overview of the various molecular mechanisms involved in insulin-dependent glucose homeostasis in skeletal muscle, as insulin resistance at this major peripheral site impacts whole body glucose homeostasis.

Periodontal Microorganisms and Cardiovascular Risk Markers in Youth With Type 1 Diabetes and Without Diabetes

BACKGROUND

A subset of periodontal microorganisms has been associated with cardiovascular disease (CVD), which is the leading complication of type 1 diabetes (t1DM). The authors therefore evaluated the association between periodontal microorganism groups and early markers of CVD in youth with t1DM.

METHODS

A cross-sectional analysis was conducted among youth aged 12 to 19 years at enrollment; 105 had t1DM for ≥5 years and were seeking care at the Barbara Davis Center, University of Colorado, from 2009 to 2011, and 71 did not have diabetes. Subgingival plaque samples were assessed for counts of 41 periodontal microorganisms using DNA-DNA hybridization. Microorganisms were classified using cluster analysis into four groups named red-orange, orange-green, blue/other, and yellow/other, modified from Socransky's color scheme for periodontal microorganisms. Subsamples (54 with t1DM and 48 without diabetes) also received a periodontal examination at the University of Colorado School of Dental Medicine.

RESULTS

Participants were ≈15 years old on average, and 74% were white. Mean periodontal probing depth was 2 mm (SE 0.02), and 17% had bleeding on probing. In multivariable analyses, glycated hemoglobin (HbA1c) was inversely associated with the yellow/other cluster (microorganisms that are not associated with periodontal disease) among youth with t1DM. Blood pressure, triglycerides, low-density lipoprotein, high-density lipoprotein, and total cholesterol were not associated with microorganism clusters in this group. HbA1c was not associated with periodontal microorganism clusters among youth without diabetes.

CONCLUSION

Among youth with t1DM who had good oral health, periodontal microorganisms were not associated with CVD risk factors.

Extracellular vesicles: Pharmacological modulators of the peripheral and central signals governing obesity

Obesity and its metabolic resultant dysfunctions such as insulin resistance, hyperglycemia, dyslipidemia and hypertension, grouped as the "metabolic syndrome", are chronic inflammatory disorders that represent one of the most severe epidemic health problems. The imbalance between energy intake and expenditure, leading to an excess of body fat and an increase of cardiovascular and diabetes risks, is regulated by the interaction between central nervous system (CNS) and peripheral signals in order to regulate behavior and finally, the metabolism of peripheral organs. At present, pharmacological treatment of obesity comprises actions in both CNS and peripheral organs. In the last decades, the extracellular vesicles have emerged as participants in many pathophysiological regulation processes. Whether used as biomarkers, targets or even tools, extracellular vesicles provided some promising effects in the treatment of a large variety of diseases. Extracellular vesicles are released by cells from the plasma membrane (microvesicles) or from multivesicular bodies (exosomes) and contain lipids, proteins and nucleic acids, such as DNA, protein coding, and non-coding RNAs. Owing to their composition, extracellular vesicles can (i) activate receptors at the target cell and then, the subsequent intracellular pathway associated to the specific receptor; (ii) transfer molecules to the target cells and thereby change their phenotype and (iii) be used as shuttle of drugs and, thus, to carry specific molecules towards specific cells. Herein, we review the impact of extracellular vesicles in modulating the central and peripheral signals governing obesity.

Wheat gluten intake increases weight gain and adiposity associated with reduced thermogenesis and energy expenditure in an animal model of obesity

BACKGROUND/OBJECTIVES

The association between gluten and body weight is inconsistent. Previously, we showed that a gluten-free diet reduces weight gain without changing food intake in mice fed high-fat diets. In the present study, we investigated the effects of gluten intake on fat metabolism, thermogenesis and energy expenditure in mice fed a standard or high-fat diet.

METHODS

Mice were fed four different experimental diets during 8 weeks: a control-standard diet (CD), a CD added with 4.5% of wheat gluten (CD-G), a high-fat diet (HFD) and a HFD added with 4.5% of wheat gluten (HFD-G). After 8 weeks, the mice received (99m)Tc-radiolabeled gluten orally to study gluten absorption and biodistribution or they underwent indirect calorimetry. After killing, subcutaneous and brown adipose tissues (SAT and BAT) were collected to assess thermogenesis-related protein expression. Lipid metabolism was studied in adipocyte cultures from the four groups.

RESULTS

Despite having had the same energy intake, CD-G and HFD-G mice exhibited increased body weight and fat deposits compared with their respective controls. (99m)Tc-GLU or its peptides were detected in the blood, liver and visceral adipose tissue, suggesting that gluten can even reach extraintestinal organs. Uncoupling protein-1 expression was reduced in the BAT of HFD-G and in the SAT of CD-G and HFD-G mice. Indirect calorimetry showed lower oxygen volume consumption in CD-G and HFD-G groups compared with their controls. In HFD mice, daily energy expenditure was reduced with gluten intake. Gluten also reduced adiponectin, peroxisome proliferator-activated receptor (PPAR)-α and PPARγ and hormone-sensitive lipase in cultures of isolated adipocytes from HFD mice, whereas in the CD-G group, gluten intake increased interleukin-6 expression and tended to increase that of tumor necrosis factor.

CONCLUSIONS

Wheat gluten promotes weight gain in animals on both HFD and CD, partly by reducing the thermogenic capacity of adipose tissues.

Impact of Reduced ATGL-Mediated Adipocyte Lipolysis on Obesity-Associated Insulin Resistance and Inflammation in Male Mice

Emerging evidence suggests that impaired regulation of adipocyte lipolysis contributes to the proinflammatory immune cell infiltration of metabolic tissues in obesity, a process that is proposed to contribute to the development and exacerbation of insulin resistance. To test this hypothesis in vivo, we generated mice with adipocyte-specific deletion of adipose triglyceride lipase (ATGL), the rate-limiting enzyme catalyzing triacylglycerol hydrolysis. In contrast to previous models, adiponectin-driven Cre expression was used for targeted ATGL deletion. The resulting adipocyte-specific ATGL knockout (AAKO) mice were then characterized for metabolic and immune phenotypes. Lean and diet-induced obese AAKO mice had reduced adipocyte lipolysis, serum lipids, systemic lipid oxidation, and expression of peroxisome proliferator-activated receptor alpha target genes in adipose tissue (AT) and liver. These changes did not increase overall body weight or fat mass in AAKO mice by 24 weeks of age, in part due to reduced expression of genes involved in lipid uptake, synthesis, and adipogenesis. Systemic glucose and insulin tolerance were improved in AAKO mice, primarily due to enhanced hepatic insulin signaling, which was accompanied by marked reduction in diet-induced hepatic steatosis as well as hepatic immune cell infiltration and activation. In contrast, although adipocyte ATGL deletion reduced AT immune cell infiltration in response to an acute lipolytic stimulus, it was not sufficient to ameliorate, and may even exacerbate, chronic inflammatory changes that occur in AT in response to diet-induced obesity.

Evaluation of serum interleukin-10 levels as a predictor of glycemic alteration in chronic periodontitis and type 2 diabetes mellitus

Aim:

Chronic periodontal disease (CPD) and type 2 diabetes mellitus (T2DM) share common pathogenic pathways. This study aimed to estimate levels of serum interleukin (IL-10), an anti-inflammatory cytokine also associated with T2DM and evaluate its association with hyperglycemia.

Materials and Methods:

This investigation involved sixty participants divided into four groups comprising 15 participants each: Group 1 (healthy controls), Group 2 (CPD patients), Group 3 (T2DM patients with CPD) and Group 4 (T2DM patients). Plaque index, gingival index, probing pocket depths (PPD), clinical attachment loss, bleeding on probing, random blood sugar, glycosylated hemoglobin (HbA1c), and serum IL-10 was measured.

Results:

Interleukin-10 was detected in all four groups. Statistically significant (P < 0.05) differences were observed in most of the variables in all groups. IL-10 correlated significantly with PPD in Group 1 and with HbA1c in Group 4. IL-10 regressed with PPD in Group 1 and with HbA1c in Group 4. IL-10 levels were lower in Group 3 when compared with Group 4 and was lowest in Group 2.

Conclusion:

Low IL-10 levels associated with high HbA1c. Pathogenic mechanisms of CPD seem to regulate IL-10. Serum IL-10 levels may be one of the predictors of glycemia.

GIP increases adipose tissue expression and blood levels of MCP-1 in humans and links high energy diets to inflammation: a randomised trial

AIMS/HYPOTHESIS

Obesity is associated with elevated monocyte chemoattractant protein-1 (MCP-1), a proinflammatory chemokine related to diabetes and cardiovascular disease. Since obesity is triggered by energy dense diets, we hypothesised that nutrient induced intestinal hormones such as glucose-dependent insulinotropic peptide (GIP) may directly stimulate the release of chemokines from adipose tissue and induce low-grade inflammation.

METHODS

GIP effects on gene expression and secretion of inflammatory markers were studied by microarray analysis and PCR from human subcutaneous fat biopsies of slightly obese but healthy volunteers in the metabolic ward of German Institute of Human Nutrition, Department of Clinical Nutrition, Potsdam-Rehbrücke. To allocate the participants to the study arms they were numbered in order of their recruitment and then assigned to the groups by a random number generator. In a randomised, single-blind (participants) crossover design, the participants received GIP infusions in postprandial concentrations (2 pmol kg(-1) min(-1)) or saline (154 mmol/l NaCl) infusions for 240 min either alone, in combination with hyperinsulinaemic-euglycaemic (EU) or hyperinsulinaemic-hyperglycaemic (HC) clamps. Possible mechanisms of GIP effects were investigated in single and co-cultures of macrophage and adipocyte cell lines and in primary human monocytes, macrophages and adipocytes.

RESULTS

A total of 17 participants were randomised to the following groups: EU with GIP infusion (n = 9); EU with NaCl infusion (n = 9); HC with GIP infusion (n = 8); HC with NaCl infusion (n = 8); sole GIP infusion (n = 11) and sole placebo infusion (n = 11). All 17 individuals were analysed. The study is completed. In human subcutaneous adipose tissue (hSCAT), infusions of GIP significantly increased inflammatory chemokine and cytokine gene networks in transcriptomic microarray analyses. Particularly MCP-1 (180 ± 26%), MCP-2 (246 ± 58%) and IL-6 (234 ± 40%) mRNA levels in adipose tissue as well as circulating plasma concentrations of MCP-1 (165 ± 12 vs 135 ± 13 pg/ml; GIP vs saline after 240 min; p < 0.05 for all variables) in humans increased independently of circulating insulin or glucose plasma concentrations. GIP stimulation increased Mcp-1 mRNA-expression in co-cultures of differentiated 3T3L1-adipocytes and RAW 264.7 macrophages but not in the isolated cell lines. Similarly, GIP increased MCP-1 transcripts in co-cultures of primary human macrophages with human adipocytes. GIP receptor (GIPR) transcripts were present in primary monocytes and the different cell lines and induced activation of extracellular related kinase (ERK) as well as increases in cAMP, indicating functional receptors.

CONCLUSIONS/INTERPRETATION

Our findings suggest that the nutrient induced gut hormone GIP may initiate adipose tissue inflammation by triggering a crosstalk of adipocytes and macrophages involving MCP-1.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00774488.

FUNDING

This work was supported by the German Research Foundation (DFG): grant No. Pf164/021002.

Fat in flames: influence of cytokines and pattern recognition receptors on adipocyte lipolysis

Adipose tissue has the largest capacity to store energy in the body and provides energy through the release of free fatty acids during times of energy need. Different types of immune cells are recruited to adipose tissue under various physiological conditions, indicating that these cells contribute to the regulation of adipose tissue. One major pathway influenced by a number of immune cells is the release of free fatty acids through lipolysis during both physiological (e.g., cold stress) and pathophysiological processes (e.g., obesity, type 2 diabetes). Adipose tissue expansion during obesity leads to immune cell infiltration and adipose tissue remodeling, a homeostatic process that promotes inflammation in adipose tissue. The release of proinflammatory cytokines stimulates lipolysis and causes insulin resistance, leading to adipose tissue dysfunction and systemic disruptions of metabolism. This review focuses on the interactions of cytokines and other inflammatory molecules that regulate adipose tissue lipolysis during physiological and pathophysiological states.

Tumor Necrosis Factor-Α, Interleukin-6, C-Reactive Protein Levels and Insulin Resistance Associated with Type 2 Diabetes in Abdominal Obesity Women

We aim to investigate the association between elevated tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and high sensitivity-C-reactive protein (hs-CRP) with type 2 diabetes mellitus (T2DM) in abdominal obesity (AO) women subjects. A total of 428 AO subjects (age 48.4 ± 10.2 years), and 107 non-AO women subjects (age 48.8 ± 11.8 years) were enrolled for the all biochemistry testing, inflammatory cytokines, fasting insulin and Homeostasis Model Assessment of insulin resistance (HOMA-IR). Body mass index, waist circumference (WC), blood pressure (BP), plasma glucose (Glu), triglyceride (TG), insulin, HOMA-IR and inflammatory cytokines were significantly higher and lower total antioxidant capacity, HDL-C in AO subjects (p < 0.05). WC was significantly correlated with BP, Glu, TG, LDL-C, insulin, HOMA-IR, TNF-α, IL-6 and negative correlation with HDL-C in AO subjects. Elevation of TNF-α, IL-6, hs-CRP and insulin resistance were significantly associated with T2DM in AO subjects, after adjusting with insulin resistance, increased oxidative stress, elevated TG and reduced HDL-C by using multiple logistic regression analysis. In conclusions, elevation of inflammatory cytokines, oxidative stress and insulin resistance were associated with T2DM in AO women subjects. These inflammatory cytokines are positively associated with T2DM and may have a causal relation with an increased oxidative stress and insulin resistance in these AO women subjects.

Monocytes from patients with rheumatoid arthritis and type 2 diabetes mellitus display an increased production of interleukin (IL)-1β via the nucleotide-binding domain and leucine-rich repeat containing family pyrin 3(NLRP3)-inflammasome activation: a possible implication for therapeutic decision in these patients

A better understanding about the mechanisms involved in the pathogenesis of type 2 diabetes mellitus (T2D) showed that inflammatory cytokines such as tumour necrosis factor (TNF) and interleukin (IL)-1β play a pivotal role, mirroring data largely reported in rheumatoid arthritis (RA). IL-1β is produced mainly by monocytes (MO), and hyperglycaemia may be able to modulate, in the cytoplasm of these cells, the assembly of a nucleotide-binding domain and leucine-rich repeat containing family pyrin (NLRP3)-inflammosome, a cytosolic multi-protein platform where the inactive pro-IL-1β is cleaved into active form, via caspase-1 activity. In this paper, we evaluated the production of IL-1 β and TNF, in peripheral blood MO of patients affected by RA or T2D or both diseases, in order to understand if an alteration of the glucose metabolism may influence their proinflammatory status. Our data showed, after 24 h of incubation with different glucose concentrations, a significantly increased production of IL-1β and TNF in all evaluated groups when compared with healthy controls. However, a significant increase of IL-1β secretion by T2D/RA was observed when compared with other groups. The analysis of relative mRNA expression confirmed these data. After 24 h of incubation with different concentrations of glucose, our results showed a significant increase in NLRP3 expression. In this work, an increased production of IL-1β by MO obtained from patients affected by both RA and T2D via NLRP3-inflammasome activation may suggest a potential IL-1β targeted therapy in these patients.

Chronic Elevation of Tumor Necrosis Factor-α Mediates the Impairment of Leptomeningeal Arteriogenesis in db/db Mice

Background and Purpose—

Leptomeningeal collateral growth is a key factor that defines the severity of ischemic stroke. Patients with stroke generally have vascular risk factors, such as diabetes mellitus; however, consensus is lacking on how diabetes mellitus affects leptomeningeal arteriogenesis. We investigate the influence of diabetes mellitus on the leptomeningeal arteriogenesis.

Methods—

We measured the vessel diameter of the leptomeningeal anastomoses 14 days after the common carotid artery occlusion in db/db, db/+, and streptozotocin-induced hyperglycemic mice. In another set of these mice, we measured the infarct volume attributed to subsequent middle cerebral artery occlusion 14 days after the common carotid artery occlusion. Mac-2–positive cells on the dorsal brain surface and the mRNA expression of several macrophage-related factors in the cerebral cortex were examined. Finally, we tested whether the leptomeningeal arteriogenesis could be restored by pharmaceutical intervention in the db/db mice.

Results—

Cerebral hypoperfusion led to significant ipsilateral leptomeningeal collateral growth in db/+ mice and streptozotocin-induced hyperglycemic mice. The collateral growth contributed to reduced infarct volume. In contrast, leptomeningeal arteriogenesis was impaired in the db/db mice. The number of Mac-2–positive cells was increased and tumor necrosis factor-α mRNA expression was induced after common carotid artery occlusion in the db/+ mice. However, these responses were not observed in the db/db mice. Administration of the tumor necrosis factor-α inhibitor etanercept before common carotid artery occlusion restored the hypoperfusion-induced leptomeningeal collateral growth in db/db mice.

Conclusions—

These results indicate that leptomeningeal arteriogenesis is impaired in db/db mice and that suppression of the tumor necrosis factor-α response to hypoperfusion is the major contributing factor.

TLR4 at the Crossroads of Nutrients, Gut Microbiota, and Metabolic Inflammation

Obesity is accompanied by the activation of low-grade inflammatory activity in metabolically relevant tissues. Studies have shown that obesity-associated insulin resistance results from the inflammatory targeting and inhibition of key proteins of the insulin-signaling pathway. At least three apparently distinct mechanisms-endoplasmic reticulum stress, toll-like receptor (TLR) 4 activation, and changes in gut microbiota-have been identified as triggers of obesity-associated metabolic inflammation; thus, they are expected to represent potential targets for the treatment of obesity and its comorbidities. Here, we review the data that place TLR4 in the center of the events that connect the consumption of dietary fats with metabolic inflammation and insulin resistance. Changes in the gut microbiota can lead to reduced integrity of the intestinal barrier, leading to increased leakage of lipopolysaccharides and fatty acids, which can act upon TLR4 to activate systemic inflammation. Fatty acids can also trigger endoplasmic reticulum stress, which can be further stimulated by cross talk with active TLR4. Thus, the current data support a connection among the three main triggers of metabolic inflammation, and TLR4 emerges as a link among all of these mechanisms.

Type 1 diabetes exacerbates blood-brain barrier alterations during experimental epileptic seizures in an animal model

The aim of this study was to perform the effects of diabetes on the permeability of the blood-brain barrier (BBB) during pentylenetetrazole (PTZ)-induced epileptic attacks. For this propose, the animals were divided into four groups. These groups contained were intact, PTZ-treated, diabetic and PTZ-treated diabetic individuals, respectively. To evaluate the functioning of the BBB, Evans blue was used as a BBB permeability indicator, and the expressions of zonula occludens-1 and glial fibrillary acidic protein involving the functioning of the BBB were determined immunohistochemically. Also, the changes in the release of serum tumour necrosis factor-alpha and interleukin-10 and interleukin-12 were studied by using enzyme-linked immunosorbent assay method. BBB permeability in the seizures under diabetic conditions showed a considerable increase (p < 0·01) in all of the brain we studied. The immunoreactive staining intensity of zonula occludens-1 and glial fibrillary acidic protein was found reduced in the brain regions of diabetic rats (p < 0·01). However, the serum level of tumour necrosis factor-alpha increased in diabetes and diabetes + PTZ groups, and the serum level of interleukin-12 increased significantly in all experimental groups (p < 0·05). In conclusion, diabetes dramatically increases BBB damage during epileptic seizures, and it may be derived from an elevation of paracellular passage.

TNF-α knockdown alleviates palmitate-induced insulin resistance in C2C12 skeletal muscle cells

Insulin resistance is a cardinal feature of Type 2 Diabetes (T2D), which accompanied by lipid accumulation and TNF-α overexpression in skeletal muscle. The role of TNF-α in palmitate-induced insulin resistance remained to be elucidated. Here, we assessed effects of TNF-α knockdown on the components of insulin signaling pathway (IRS-1 and Akt) in palmitate-induced insulin resistant C2C12 skeletal muscle cells. To reduce TNF-α expression, C2C12 cells were transduced with TNF-α-shRNA lentiviral particles. Afterwards, the protein expression of TNF-α, IRS-1, and Akt, as well as phosphorylation levels of IRS-1 and Akt were evaluated by western blot. We also measured insulin-stimulated glucose uptake in the presence and absence of palmitate. TNF-α protein expression in C2C12 cells significantly increased by treatment with 0.75 mM palmitate (P < 0.05). In TNF-α knockdown cells, the protein expression level of TNF-α was significantly decreased by almost 70% (P < 0.01) compared with the control cells. Our results also revealed that, in control cells, palmitate treatment significantly reduced the insulin-induced phosphorylations of IRS-1 (Tyr632) and Akt (Ser473) by 60% and 66% (P < 0.01), respectively. Interestingly, these phosphorylations, even in the presence of palmitate, were not significantly reduced in TNF-α knockdown cells with respect to the untreated control cells (P > 0.05). Furthermore, palmitate significantly reduced insulin-dependent glucose uptake in control cells, however, it was not able to reduce insulin-stimulated glucose uptake in TNF-α knockdown cells in comparison with the untreated control cells (P < 0.01). These findings indicated that TNF-α down-regulation maintains insulin sensitivity, even in the presence of palmitate, therefore, TNF-α inhibition could be a good strategy for the treatment of palmitate-induced insulin resistance.

Regulatory effects of resveratrol on glucose metabolism and T-lymphocyte subsets in the development of high-fat diet-induced obesity in C57BL/6 mice

High-fat diet (HFD)-induced obesity is often associated with immune dysfunction. Resveratrol (trans-3,5,4'-trihydroxystilbene), which has well-founded immunity-related beneficial properties, was used to elucidate the regulatory effect on glucose metabolism and T-lymphocyte subsets in the development of HFD-induced obesity. Resveratrol, being associated with decreases of plasma leptin and plasma lipids and the release of oxidative stress, significantly decreased the body weight and fat masses in HF mice after 26 weeks of feeding. Furthermore, resveratrol decreased the fasting blood glucose and fasting plasma insulin and increased the CD3(+)CD4(+)/CD3(+)CD8(+) subsets percentages and the regulatory T cells (Tregs) production after 13 and 26 weeks of feeding. The results indicate that resveratrol, as an effective supplement for HFD, maintained glucose homeostasis by activating the PI3K and SIRT1 signaling pathways. Moreover, resveratrol activated the Nrf2 signaling pathway-mediated antioxidant enzyme expression to alleviate inflammation by protecting against oxidative damage and T-lymphocyte subset-related chronic inflammatory response in the development of HFD-induced obesity.

Infection and inflammation in somatic maintenance, growth and longevity

All organisms must display a certain degree of environmental adaptability to survive and reproduce. Growth and reproduction are metabolically expensive and carry other costs that contribute to aging. Therefore, animals have developed physiologic strategies to assess the harshness of the environment before devoting resources to reproduction. Presumably, these strategies maximize the possibility for offspring survival. Current views of aging reflect a trade-off between reproductive fitness and somatic maintenance whereby environmental stress induces an adaptive metabolic response aimed at preserving cellular integrity while inhibiting growth, whereas favorable environmental conditions (abundance of food and water, and optimal temperature, etc.) promote growth and reproductive maturity but simultaneously increase cellular damage and aging. Here we propose that the prevalence of infectious pathogens in a given niche represents an additional environmental factor that, via innate immune pathways, actively shifts this balance in favor of somatic maintenance at the expense of reproduction and growth. We additionally propose the construction of a genetic model system with which to test this hypothesis.

Time course of adipose tissue dysfunction associated with antioxidant defense, inflammatory cytokines and oxidative stress in dyslipemic insulin resistant rats

Time course of adipose tissue dysfunction in dyslipemic insulin resistant rats.

Signalling Networks Governing Metabolic Inflammation

Low-grade inflammation is an established pathological condition that contributes to the development of obesity, insulin resistance and type 2 diabetes. Metabolic inflammation is dependent on multiple signalling events. In an overnutrition state, canonical inflammatory pathways are induced by inflammatory cytokines and lipid species. They can also be triggered through inflammasome activation as well as through cellular stress provoked by the unfolded protein response at the endoplasmic reticulum as well as by reactive oxygen species. In this chapter, we summarize the current knowledge about signalling events within the cell and describe how they impact on metabolic inflammation and whole-body metabolism. We particularly highlight the interplay between different signalling pathways that link low-grade inflammation responses to the inactivation of the insulin receptor pathway, ultimately leading to insulin resistance, a hallmark of type 2 diabetes.

Diabetes and Hepatitis C: A Two-Way Association

Diabetes and hepatitis C infection are both prevalent diseases worldwide, and are associated with increased morbidity and mortality. Most studies, but not all, have shown that patients with chronic hepatitis C are more prone to develop type 2 diabetes (T2D) compared to healthy controls, as well as when compared to patients with other liver diseases, including hepatitis B. Furthermore, epidemiological studies have revealed that patients with T2D may also be at higher risk for worse outcomes of their hepatitis C infection, including reduced rate of sustained virological response, progression to fibrosis and cirrhosis, and higher risk for development of hepatocellular carcinoma. Moreover, hepatitis C infection and mainly its treatment, interferon α, can trigger the development of type 1 diabetes. In this review, we discuss the existing data on this two-way association between diabetes and hepatitis C infection with emphasis on possible mechanisms. It remains to be determined whether the new curative therapies for chronic hepatitis C will improve outcomes in diabetic hepatitis C patients, and conversely whether treatment with Metformin will reduce complications from hepatitis C virus infection. We propose an algorithm for diabetes screening and follow-up in hepatitis C patients.