Potential antiinflammatory role of insulin via the preferential polarization of effector T cells toward a T helper 2 phenotype

A proinflammatory CD4+ T cell phenotype in gestational diabetes mellitus

AIMS/HYPOTHESIS

Numerous adaptations of the maternal immune system are necessary during pregnancy to maintain immunological tolerance to the semi-allogeneic fetus. Several complications of pregnancy have been associated with dysregulation of these adaptive mechanisms. While gestational diabetes mellitus (GDM) has been associated with upregulation of circulating inflammatory factors linked to innate immunity, polarisation of the adaptive immune system has not been extensively characterised in this condition. We aimed to characterise pro- and anti-inflammatory CD4⁺ (T helper [Th]) T cell subsets in women with GDM vs women without GDM (of similar BMI), during and after pregnancy, and examine the relationship between CD4⁺ subsets and severity of GDM.

METHODS

This is a prospective longitudinal case-control study of 55 women with GDM (cases) and 65 women without GDM (controls) at a tertiary maternity hospital. Quantification of proinflammatory (Th17, Th17.1, Th1) and anti-inflammatory (regulatory T cell [Treg]) CD4⁺ T cell subsets was performed on peripheral blood at 37 weeks gestation and 7 weeks postpartum, and correlated with clinical characteristics and measures of blood glucose.

RESULTS

Women with GDM had a significantly greater percentage of Th17 (median 2.49% [interquartile range 1.62-4.60] vs 1.85% [1.13-2.98], p = 0.012) and Th17.1 (3.06% [1.30-4.33] vs 1.55% [0.65-3.13], p = 0.006) cells compared with the control group of women without GDM. Women with GDM also had higher proinflammatory cell ratios (Th17:Treg, Th17.1:Treg and Th1:Treg) in pregnancy compared with the control group of women without GDM. In the control group, there was a statistically significant independent association between 1 h glucose levels in the GTT and Th17 cell percentages, and also between 2 h glucose levels and percentage of Th17 cells. The percentage of Th17 cells and the Th17:Treg ratio declined significantly after delivery in women with GDM, whereas this was not the case with the control group of women. Nevertheless, a milder inflammatory phenotype persisted after delivery (higher Th17:Treg ratio) in women with GDM vs women without.

CONCLUSIONS/INTERPRETATION

Dysregulation of adaptive immunity supports a novel paradigm of GDM that extends beyond hyperglycaemia and altered innate immunity.

Diabetes Downregulates Allergen-Induced Airway Inflammation in Mice

Previous studies described that allergic diseases, including asthma, occur less often than expected in patients with type 1 diabetes. Here, we investigated the influence of diabetes on allergic airway inflammation in a model of experimental asthma in mice. Diabetes was induced by intravenous injection of alloxan into 12 h-fasted A/J mice, followed by subcutaneous sensitization with ovalbumin (OVA) and aluminum hydroxide (Al(OH)₃), on days 5 and 19 after diabetes induction. Animals were intranasally challenged with OVA (25 μg), from day 24 to day 26. Alloxan-induced diabetes significantly attenuated airway inflammation as attested by the lower number of total leukocytes in the bronchoalveolar lavage fluid, mainly neutrophils and eosinophils. Suppression of eosinophil infiltration in the peribronchiolar space and generation of eosinophilotactic mediators, such as CCL-11/eotaxin, CCL-3/MIP-1α, and IL-5, were noted in the lungs of diabetic sensitized mice. In parallel, reduction of airway hyperreactivity (AHR) to methacholine, mucus production, and serum IgE levels was also noted under diabetic conditions. Our findings show that alloxan diabetes caused attenuation of lung allergic inflammatory response in A/J mice, by a mechanism possibly associated with downregulation of IgE antibody production.

Obesity induced T cell dysfunction and implications for cancer immunotherapy

Obesity has been shown to increase risk for a number of different disorders, including cancer. In addition, obesity is also associated with immune dysfunction, which could contribute to its strong association with other comorbidities. Recently, the immune system has been found to be heavily regulated by changes in metabolism. In particular, T cells are able to respond to intrinsic metabolic regulatory mechanisms, as well as extrinsic factors such as the changes in metabolite availability. The dysfunctional metabolic environment created by obesity could therefore have a direct impact on T cell responses. In this review, we highlight recent findings in the fields of T cell biology and obesity, with a focus on mechanisms driving T cell dysfunction and potential implications for immunotherapeutic treatment of cancer.

Insulin resistance and lung function in obese asthmatic pre-pubertal children

BACKGROUND

Recent findings have supposed that the underlying association between the increased prevalence of both asthma and obesity may be insulin resistance (IR).

METHODS

Insulin and glucose serum levels were analyzed to calculate the homeostatic model assessment of insulin resistance (HOMA-IR) for IR in 98 pre-pubertal children. Lung function and allergy status evaluation were performed. The study population was divided into four groups: (1) obese asthmatic children (ObA); (2) normal-weight asthmatic children (NwA); (3) normal-weight non-asthmatic children (Nw) and (4) obese non-asthmatic children (Ob).

RESULTS

Forced expiratory volume in 1 s (FEV1) was slightly lower in obese subjects compared with normal-weight subjects and forced vital capacity (FVC) appeared lower in asthmatics, whereas between non-asthmatics subjects, it was lower in the obese group than in the normal-weight one. The post hoc analysis revealed a statistically significant reduction in FEV1, peak expiratory flow (PEF), forced expiratory flows (FEF) between 50% and 25% of the FVC (FEF50 and FEF25) between ObA and Nw and in FEV1, FVC, PEF, FEF50 and FEF25 between NwA and Nw, but no statistically significant differences of lung function parameters were observed between ObA and NwA. We found an inverse relationship between HOMA-IR and all spirometric parameters, although without any statistical significance. We also observed a significantly lower FVC in insulin-resistant children (HOMA-IR>95th percentile) (p=0.03).

CONCLUSIONS

This study suggests that lung function could be early altered in obese children, already in pre-pubertal age. Although IR should not manifest its effects on lungs in pre-pubertal obese children, the prevention or treatment of obesity in the pre-pubertal period may prevent definitive negative effects on lungs.

Interactions Between the Neuroendocrine System and T Lymphocytes in Diabetes

It is well established that there is a fine-tuned bidirectional communication between the immune and neuroendocrine tissues in maintaining homeostasis. Several types of immune cells, hormones, and neurotransmitters of different chemical nature are involved as communicators between organs. Apart of being key players of the adaptive arm of the immune system, it has been recently described that T lymphocytes are involved in the modulation of metabolism of several tissues in health and disease. Diabetes may result mainly from lack of insulin production (type 1 diabetes) or insufficient insulin and insulin resistance (type 2 diabetes), both influenced by genetic and environmental components. Herein, we discuss accumulating data regarding the role of the adaptive arm of the immune system in the pathogenesis of diabetes; including the action of several hormones and neurotransmitters influencing on central and peripheral T lymphocytes development and maturation, particularly under the metabolic burden triggered by diabetes. In addition, we comment on the role of T-effector lymphocytes in adipose and liver tissues during diabetes, which together enhances pancreatic β-cell stress aggravating the disease.

Association between diabetes mellitus and active tuberculosis: A systematic review and meta-analysis

The burgeoning epidemic of diabetes mellitus (DM) is one of the major global health challenges. We systematically reviewed the published literature to provide a summary estimate of the association between DM and active tuberculosis (TB). We searched Medline and EMBASE databases for studies reporting adjusted estimates on the TB–DM association published before December 22, 2015, with no restrictions on region and language. In the meta-analysis, adjusted estimates were pooled using a DerSimonian-Laird random-effects model, according to study design. Risk of bias assessment and sensitivity analyses were conducted. 44 eligible studies were included, which consisted of 58,468,404 subjects from 16 countries. Compared with non-DM patients, DM patients had 3.59–fold (95% confidence interval (CI) 2.25–5.73), 1.55–fold (95% CI 1.39–1.72), and 2.09–fold (95% CI 1.71–2.55) increased risk of active TB in four prospective, 16 retrospective, and 17 case-control studies, respectively. Country income level (3.16–fold in low/middle–vs. 1.73–fold in high–income countries), background TB incidence (2.05–fold in countries with >50 vs. 1.89–fold in countries with ≤50 TB cases per 100,000 person-year), and geographical region (2.44–fold in Asia vs. 1.71–fold in Europe and 1.73–fold in USA/Canada) affected appreciably the estimated association, but potential risk of bias, type of population (general versus clinical), and potential for duplicate data, did not. Microbiological ascertainment for TB (3.03–fold) and/or blood testing for DM (3.10–fold), as well as uncontrolled DM (3.30–fold), resulted in stronger estimated association. DM is associated with a two- to four-fold increased risk of active TB. The association was stronger when ascertainment was based on biological testing rather than medical records or self-report. The burgeoning DM epidemic could impact upon the achievements of the WHO “End TB Strategy” for reducing TB incidence.

Poly (I:C) alleviates obesity related pro-inflammatory status and promotes glucose homeostasis

Obesity associated insulin resistance (IR) is implicated in chronic inflammation that mediated by the immune system. Imbalance between anti-inflammatory and pro-inflammatory response contributes to the origins and drivers of IR. However, cells of innate and adaptive immune system participate in the pathogenesis of IR, while glucose homeostasis related immune tolerance could be compromised high fat diet (HFD) reduced metabolic disorder. Although previous studies have demonstrated that anti-inflammatory therapy has a protective role in alleviating the pro-inflammatory status in HFD induced IR, the precise mechanism is still unclear. Ploy (I:C) is a synthetic double-stranded RNA that activates innate and/or adaptive immune response via retinoic acid-inducible gene-I (RIG-I), toll-like receptor 3 (TLR3) and melanoma differentiation-associated protein 5 (MDA5). In the present study, we initially perform a novel research on the relationship between Poly (I:C) preconditioning and improved glucose metabolism in obesity related IR. Interestingly, Poly (I:C) treatment has alleviated the pro-inflammatory status and promoted glucose homeostasis during a HFD feeding. Improved insulin sensitivity is consistent with enhanced immune tolerance, which accompanied with increased Foxp3⁺ regulatory T cells (Tregs). Of note, Tregs have a pivotal role in orchestrating the self-balance between autoimmunity and inflammation reaction. Thus, our findings reveal that Ploy (I:C) preconditioning prevents HFD induced glucose intolerance, which may be recognized as vaccination by the host. Overall, selectively targeting precise immune regulators may lead to new classes of potentially meaningful therapies for IR in the clinical trials.

Cytokines and metabolic factors regulate tumoricidal T-cell function during cancer immunotherapy

Recent advances in cancer biology and genetics have fostered precision therapies targeting tumor-specific attributes. Immune-based therapies that elicit cytolytic T cells (CTL) specific for tumor antigens can provide therapeutic benefit to cancer patients, however, cure rates are typically low. This largely results from immunosuppressive mechanisms operating within the tumor microenvironment, many of which inflict metabolic stresses upon CTL. Conversely, immunotherapies can mitigate specific metabolic stressors. For instance, dual costimulation immunotherapy with CD134 (OX40) plus CD137 (4-1BB) agonists appears to mediate tumor control in part by engaging cytokine networks that enable infiltrating CTL to compete for limiting supplies of glucose. Future efforts combining modalities that endow CTL with complimentary metabolic advantages should improve therapeutic efficacies.

Insulin use increases risk of asthma but metformin use reduces the risk in patients with diabetes in a Taiwanese population cohort

OBJECTIVE

Recent reports have suggested that insulin promotes airway smooth muscle contraction and enhances airway hyperresponsiveness, which are cardinal features of asthma. In contrast, metformin can reduce both airway inflammatory and remodeling properties. However, these results are all from in vitro and animal studies. This study investigated whether diabetes and various antidiabetic agents associate with the risk of asthma.

METHODS

We used a retrospective population-based cohort study using Taiwan's National Health Insurance claim database from 2000 to 2010 and a Cox proportional hazards regression model to compare the incidence of asthma between patients with diabetes (n = 19,428) and a matched non-diabetic group (n = 38,856). We also used a case-control study nested from the above cohort including 1,982 incident cases of asthma and 1,982 age- and sex-matched controls. A time density sampling technique was used to assess the effects of various antidiabetic agents on the risk of asthma.

RESULTS

The incidence of asthma was significantly higher in the diabetic cohort than that in the non-diabetic cohort after adjustment for age, sex, and obesity, with a hazard ratio of 1.30 (95% confidence interval [CI]: 1.24-1.38). Insulin was found to increase the risk of asthma among diabetic patients (odds ratio [OR] 2.23; 95% CI: 1.52-3.58). In contrast, the use of metformin correlated with a decreased risk of asthma (OR 0.75; 95% CI: 0.60-0.95).

CONCLUSIONS

Individuals with diabetes are at an increased risk of asthma. Insulin may further increase the risk of asthma, but the risk could possibly be reduced by using metformin.

The Insulin Receptor Plays a Critical Role in T Cell Function and Adaptive Immunity

T cell activation is an energy-demanding process fueled by increased glucose consumption and accompanied by upregulation of the insulin receptor (INSR). In this article, we report that silencing the INSR in inducible knockdown rats impairs selective T cell functions but not thymocyte development. Glucose transport and glycolysis in activated CD4⁺ T cells were compromised in the absence of the INSR, which was associated with alterations in intracellular signaling pathways. The observed metabolic defects coincided with reduced cytokine production, proliferation, and migration, as well as increased apoptosis of CD4⁺ T cells. The cytotoxicity of CD8⁺ T cells in response to alloantigens was also diminished under these conditions, whereas the frequency and suppressive capacity of regulatory T cells were unaffected. The observed impairments proved to be decisive in vivo because silencing of the INSR attenuated clinical symptoms in animal models of acute graft-versus-host disease and multiple sclerosis. Taken together, our results suggest that upregulation of the INSR on T cells following activation is required for efficient adaptive immunity.

Insulin resistance increases loss of antibody to hepatitis B surface antigen in nondiabetic healthy adults

The aim of this study was to evaluate the impact of insulin resistance on the persistence of a protective level of anti-HBs (hepatitis B surface antigen) in a nondiabetic general population. A cohort study was designed comprising of 38 473 Korean men and women with anti-HBs at concentrations ≥10 mIU/mL, who underwent a health examination. Insulin resistance was assessed with a homoeostasis model assessment of insulin resistance (HOMA-IR). A decline in anti-HBs to <10 mIU/L during the follow-up was considered to be a loss of protective anti-HBs. Cox-proportional hazard models were used to estimate the adjusted hazard ratios and 95% confidence intervals for anti-HBs loss across quintiles of HOMA-IR and insulin. We identified 20 826 incidents of loss of anti-HBs antibody during 180 522 person-years of follow-up (incident rate 11.5 per 100 person-years). Increasing HOMA-IR was positively associated with incident loss of anti-HBs. The multivariable-adjusted hazard ratios (95% confidence intervals) for incident loss of anti-HBs comparing quintiles 2-5 vs quintile 1 of HOMA-IR were 1.09 (1.04-1.14), 1.14 (1.09-1.19), 1.14 (1.09-1.19) and 1.21 (1.16-1.27), respectively. These associations were stronger in younger individuals under the age of 35 than in people 35 years of age or older (P for interaction = 0.004). The association was also more evident in subjects with higher titres (≥100 mIU/mL) of anti-HBs than in those with low titres (P for interaction < 0.001). Insulin resistance was associated with an increased risk for loss of vaccine-acquired anti-HBs in a large sample of a nondiabetic, general population, indicating a possible role of insulin resistance in vaccine-induced immunity.

Effects of insulin on the skin: possible healing benefits for diabetic foot ulcers

Diabetic foot ulcers affect 15-20 % of all diabetic patients and remain an important challenge since the available therapies have limited efficacy and some of the novel therapeutic approaches, which include growth factors and stem cells, are highly expensive and their safety remains to be evaluated. Despite its low cost and safety, the interest for topical insulin as a healing agent has increased only in the last 20 years. The molecular mechanisms of insulin signaling and its metabolic effects have been well studied in its classical target tissues. However, little is known about the specific effects of insulin in healthy or even diabetic skin. In addition, the mechanisms involved in the effects of insulin on wound healing have been virtually unknown until about 10 years ago. This paper will review the most recent advances in the cellular and molecular mechanisms that underlie the beneficial effects of insulin on skin wound healing in diabetes. Emerging evidence that links dysfunction of key cellular organelles, namely the endoplasmic reticulum and the mitochondria, to changes in the autophagy response, as well as the impaired wound healing in diabetic patients will also be discussed along with the putative mechanisms whereby insulin could regulate/modulate these alterations.

Effects of insulin on pharmacodynamics of immunosuppressive drugs against mitogen-activated human peripheral blood mononuclear cells

CONTEXT

Diabetes mellitus is one of the most common causes of chronic renal failure. Immunosuppressive efficacies of glucocorticoids, calcineurin inhibitors, and mycophenolic acid are possibly affected by insulin after renal transplantation in these patients.

OBJECTIVES

We investigated the effects of insulin on responses of mitogen-activated human peripheral blood mononuclear cells (PBMCs) to several immunosuppressive drugs.

MATERIALS AND METHODS

Antiproliferative efficacies of prednisolone, hydrocortisone, cyclosporine, tacrolimus, and mycophenolic acid against concanavalin A-stimulated PBMCs were evaluated in the presence of physiological (5 μunits/mL) and super physiological (50 μunits/mL) concentrations of insulin. Insulin-receptor expressions on PBMCs were evaluated by flow cytometry.

RESULTS

Insulin itself had no effects on the mitogen-induced proliferation of PBMCs. The IC50 values of cyclosporine against the mitogen-activated PBMCs in the presence of 5 or 50 μunits/mL insulin were significantly higher than those of cyclosporine without insulin (p < 0.05). The IC50 values of mycophenolic acid significantly increased by 50 μunits/mL insulin (p < 0.01). Insulin receptors were detected on the mitogen-activated CD4(+)/CD14(+ )cells in PBMCs.

DISCUSSION AND CONCLUSIONS

These results indicate that insulin at even physiological concentration attenuates suppressive efficacies of several immunosuppressive drugs against mitogen-activated proliferation of human PBMCs, possibly via insulin receptors. Insulin used in dialysis patients accompanying diabetes mellitus is suggested to attenuate efficacies of immunosuppressive drugs after renal transplantation.

The Cellular and Molecular Basis of Translational Immunometabolism

The immune response requires major changes to metabolic processes, and indeed, energy metabolism and functional activation are fully integrated in immune cells to determine their ability to divide, differentiate, and carry out effector functions. Immune cell metabolism has therefore become an attractive target area for therapeutic purposes. A neglected aspect in the translation of immunometabolism is the critical connection between systemic and cellular metabolism. Here, we discuss the importance of understanding and manipulating the integration of systemic and immune cell metabolism through in-depth analysis of immune cell phenotype and function in human metabolic diseases and, in parallel, of the effects of conventional metabolic drugs on immune cell differentiation and function. We examine how the recent identification of selective metabolic programs operating in distinct immune cell subsets and functions has the potential to deliver tools for cell- and function-specific immunometabolic targeting.

Impact of Obesity and Metabolic Syndrome on Immunity

Obesity is associated with metabolic disturbances that cause tissue stress and dysfunction. Obese individuals are at a greater risk for chronic disease and often present with clinical parameters of metabolic syndrome (MetS), insulin resistance, and systemic markers of chronic low-grade inflammation. It has been well established that cells of the immune system play an important role in the pathogenesis of obesity- and MetS-related chronic diseases, as evidenced by leukocyte activation and dysfunction in metabolic tissues such as adipose tissue, liver, pancreas, and the vasculature. However, recent findings have highlighted the substantial impact that obesity and MetS parameters have on immunity and pathogen defense, including the disruption of lymphoid tissue integrity; alterations in leukocyte development, phenotypes, and activity; and the coordination of innate and adaptive immune responses. These changes are associated with an overall negative impact on chronic disease progression, immunity from infection, and vaccine efficacy. This review presents an overview of the impact that obesity and MetS parameters have on immune system function.

Obesity: impact of infections and response to vaccines

Obesity is a common condition that has rapidly increased in both the industrialised and developing world in recent decades. Obese individuals show increased risk factors for severe infections and significant immune system dysregulation that may impair the immune response to vaccines. The main aim of this paper was to review the current knowledge regarding the association between obesity and the risk and outcome of infections as well as immune response to vaccines. The results showed that obesity is a highly complex clinical condition in which the functions of several organ and body systems, including the immune system, are modified. However, only a small minority of the biological mechanisms that lead to reduced host defences have been elucidated. Relevant efforts for future research should focus on obese children, as the available data on this population are scarce compared with the adult population. Even if most vaccines are given in the first months of life when obesity is rare, some vaccines require booster doses at preschool age, and other vaccines, such as the influenza vaccine, are recommended yearly in the obese population, but it is not known whether response to vaccines of obese patients is impaired. The reduced immune response of obese patients to vaccination can be deleterious not only for the patient but also for the community.

Associations of Circulating Lymphocyte Subpopulations with Type 2 Diabetes: Cross-Sectional Results from the Multi-Ethnic Study of Atherosclerosis (MESA)

OBJECTIVE

Distinct lymphocyte subpopulations have been implicated in the regulation of glucose homeostasis and obesity-associated inflammation in mouse models of insulin resistance. Information on the relationships of lymphocyte subpopulations with type 2 diabetes remain limited in human population-based cohort studies.

METHODS

Circulating levels of innate (γδ T, natural killer (NK)) and adaptive immune (CD4+ naive, CD4+ memory, Th1, and Th2) lymphocyte subpopulations were measured by flow cytometry in the peripheral blood of 929 free-living participants of the Multi-Ethnic Study of Atherosclerosis (MESA). Cross-sectional relationships of lymphocyte subpopulations with type 2 diabetes (n = 154) and fasting glucose and insulin concentrations were evaluated by generalized linear models.

RESULTS

Each standard deviation (SD) higher CD4+ memory cells was associated with a 21% higher odds of type 2 diabetes (95% CI: 1-47%) and each SD higher naive cells was associated with a 22% lower odds (95% CI: 4-36%) (adjusted for age, gender, race/ethnicity, and BMI). Among participants not using diabetes medication, higher memory and lower naive CD4+ cells were associated with higher fasting glucose concentrations (p<0.05, adjusted for age, sex, and race/ethnicity). There were no associations of γδ T, NK, Th1, or Th2 cells with type 2 diabetes, glucose, or insulin.

CONCLUSIONS

A higher degree of chronic adaptive immune activation, reflected by higher memory and lower naive CD4+ cells, was positively associated with type 2 diabetes. These results are consistent with a role of chronic immune activation and exhaustion augmenting chronic inflammatory diseases, and support the importance of prospective studies evaluating adaptive immune activation and type 2 diabetes.

Persistent hyperglycemia modulates gut immune function and microbiota in rats

Background

Since hyperglycemia-induced cellular dysfunction could be associated with alterations of the immune system, we tested the hypothesis that hyperglycemia augments the aberrant immune responses such as inflammation and differentiation of CD4⁺ T lymphocytes in the mesenteric lymph nodes (MLNs), and induces alterations of microbiota both under physiological and pathological conditions.

Methods

Male Wistar rats were randomly allocated into 4 groups: Control and Endotoxemia (lipopolysaccharide, LPS 1 mg/kg) with or without hyperglycemia. The hyperglycemia groups were administered glucose solution (10-40 %), while the normoglycemia groups were administered saline. Alterations of the mRNA expressions of inflammatory cytokines and CD4⁺ T lymphocyte transcriptional factor expressions in the MLNs, and those of the intestinal microbiota were analyzed at 24 hr.

Results

Hyperglycemia was kept approximately 250–350 mg/dL during the 24 hr study period. At the end of 24 hr, hyperglycemia augmented the mRNA expressions of interleukin (IL)-1β and IL-6 in the MLNs, while both the helper T (Th) 2 and regulatory-T (Treg) transcriptional factors were simultaneously up-regulated under non-endotoxemic condition. LPS injection significantly modulated the obligate anaerobe bacterial populations of the Bacteroidetes class, and altered the population sizes of the Clostridium perfringens and the Bacteroides fragilis subgroup. Hyperglycemia did not enhance these alterations of the microbiota evoked by LPS, although it did modify the bacterial populations of the L. reuteri subgroup and staphylococci in healthy condition without endotoxemia.

Conclusions

The present study indicates that both gut immune function and microbiota are significantly modulated by persistent hyperglycemia.

Electronic supplementary material

The online version of this article (doi:10.1186/s40560-015-0101-8) contains supplementary material, which is available to authorized users.

GIMAP GTPase family genes: potential modifiers in autoimmune diabetes, asthma, and allergy

GTPase of the immunity-associated protein (GIMAP) family members are differentially regulated during human Th cell differentiation and have been previously connected to immune-mediated disorders in animal studies. GIMAP4 is believed to contribute to the Th cell subtype-driven immunological balance via its role in T cell survival. GIMAP5 has a key role in BB-DR rat and NOD mouse lymphopenia. To elucidate GIMAP4 and GIMAP5 function and role in human immunity, we conducted a study combining genetic association in different immunological diseases and complementing functional analyses. Single nucleotide polymorphisms tagging the GIMAP haplotype variation were genotyped in Finnish type 1 diabetes (T1D) families and in a prospective Swedish asthma and allergic sensitization birth cohort. Initially, GIMAP5 rs6965571 was associated with risk for asthma and allergic sensitization (odds ratio [OR] 3.74, p = 0.00072, and OR 2.70, p = 0.0063, respectively) and protection from T1D (OR 0.64, p = 0.0058); GIMAP4 rs13222905 was associated with asthma (OR 1.28, p = 0.035) and allergic sensitization (OR 1.27, p = 0.0068). However, after false discovery rate correction for multiple testing, only the associations of GIMAP4 with allergic sensitization and GIMAP5 with asthma remained significant. In addition, transcription factor binding sites surrounding the associated loci were predicted. A gene-gene interaction in the T1D data were observed between the IL2RA rs2104286 and GIMAP4 rs9640279 (OR 1.52, p = 0.0064) and indicated between INS rs689 and GIMAP5 rs2286899. The follow-up functional analyses revealed lower IL-2RA expression upon GIMAP4 knockdown and an effect of GIMAP5 rs2286899 genotype on protein expression. Thus, the potential role of GIMAP4 and GIMAP5 as modifiers of immune-mediated diseases cannot be discarded.

Metabolic syndrome and risk of cancer: which link?

Metabolic syndrome (MS) is characterized by a group of metabolic disturbances which lead to an enhanced risk of cardiovascular diseases and type 2 diabetes mellitus. MS constitutes a preoccupant issue with elevated prevalence in the western countries and is often related with cancer development. Elucidating the mechanisms linking these two pathologies is, therefore, essential to identify potential therapeutic molecular targets for cancer treatment in MS patients. The main goals of this review are, to identify the relation between MS and cancer development, handling specifically each one of the main players on this process: insulin and IGF system, estrogen, pro-inflammatory cytokines and others; and, given that colorectal cancer is one of the most prevalent types of cancer in MS patients, we intend to particularly highlight the mechanisms that promote colorectal cancer development in MS individuals. Finally, we will also focus on the clinical implications of the presented mechanisms on cancer therapy and care.

Metabolic mysteries of the inflammatory response: T cell polarization and plasticity

While simultaneously maintaining homeostasis and reducing further harm to the host, the immune system is equipped to eliminate both tumors and pathogenic microorganisms. Bifurcated into cell-mediated and humoral immunity, the adaptive immune system requires a series of complex and coordinated signals to drive the proliferation and differentiation of appropriate subsets. These include signals that modulate cellular metabolism. When first published in the 1920s, "the Warburg effect" was used to describe a phenomenon in which most cancer cells relied on aerobic glycolysis to meet their biosynthetic demands. Despite the early observations of Warburg and his colleagues, targeting cancer cell metabolism for therapeutic purposes still remains theoretical. Notably, many T cells exhibit the same Warburg metabolism as cancer cells and the therapeutic benefit of targeting their metabolic pathways has since been reexamined. Emerging evidence suggests that specific metabolic alterations associated with T cells may be ancillary to their subset differentiation and influential in their inflammatory response. Thus, T cell lymphocyte activation leads to skewing in metabolic plasticity, and issue that will be the subject of this review.

Protection of streptozotocin induced insulin receptor dysfunction, neuroinflammation and amyloidogenesis in astrocytes by insulin

Impaired insulin signaling, amyloid pathology and neuroinflammation are closely associated with neurodegenerative disorder like Alzheimer's disease (AD). Our earlier studies showed that intracerebroventricular streptozotocin (STZ) induces insulin receptor (IR) signaling defect in the hippocampus, which is associated with memory impairment in rats. Astrocytes are the most abundant cells in the brain and play a major role in neuroinflammation. However, involvement of astrocytes in STZ induced IR dysfunction has not received much attention. Therefore, the present study was planned to explore the effect of STZ on IR signaling, proinflammatory markers and amyloidogenesis in rat astrocytoma cell line, (C6). STZ (100 μM) treatment in astrocytes (n = 3) for 24 h, resulted significant decrease in IR mRNA and protein expression, phosphorylation of IRS-1, Akt, GSK-3α and GSK-3β (p < 0.01). Further STZ induced amyloidogenic protein expression as evidenced by the increase in APP, BACE-1 and Aβ1-42 expression (p < 0.05) in astrocytes. STZ also significantly induced astrocytes activation as evidenced by increased expression of GFAP and p-P38 MAPK (p < 0.05). STZ treatment caused enhanced translocation of p65 NF-kB, triggered over expression of TNF-α, IL-1β, COX-2, oxidative/nitrosative stress and caspase activation (p < 0.05) in astrocytes. Insulin (25-100 nM) pretreatment (n = 3) significantly prevented changes in IR signaling, amyloidogenic protein expression and levels of proinflammatory markers (p < 0.05) in STZ treated astroglial cells. In the present study, the protective effect of insulin suggests that, IR dysfunction along with amyloidogenesis and neuroinflammation may have played a major role in STZ induced toxicity in astrocytes which are relevant to AD pathology.

Use of insulin to decrease septic shock-induced myocardial depression in a porcine model

Insulin is known to attenuate septic shock-induced myocardial depression. Possible mechanisms include an anti-inflammatory or inotropic effect of insulin. The objective of this study was to determine whether the mechanism of action of insulin in attenuating septic shock-induced myocardial depression is through an immunomodulatory effect. Fourteen pigs were assigned to one of two groups. Both groups received a 4-h infusion of lipopolysaccharide endotoxin from Escherichia coli 0111:B4. Group 2 additionally received insulin at 1.5 U/kg/h with infusions of D50 normal saline and KCl to maintain normal serum glucose and potassium levels. Cardiac function was measured with shortening fraction using transthoracic echocardiogram. Plasma TNF-α, IL-1β, and IL-6 levels were obtained every 30 min. Postmortem cytokine analysis and histomorphology were performed on the heart tissue. Although insulin attenuated septic shock-induced myocardial depression, this was not due to an anti-inflammatory effect and, therefore, likely resulted from an inotropic effect of insulin.

Insulin alleviates the inflammatory response and oxidative stress injury in cerebral tissues in septic rats

Sepsis-associated encephalopathy (SAE) is a diffuse brain dysfunction that occurs secondary to infection in the body without overt central nervous system (CNS) infection. SAE is frequently encountered in critically ill patients in intensive care units and can be detected in up to 50–70% of septic patients. Previous studies have demonstrated that inflammatory cytokine release and oxidative stress injury are major pathophysiological mechanisms of SAE in critically ill patients. However, there are no effective strategies for the treatment of SAE. Insulin has important immunomodulatory effects and protective effects against oxidative stress injury in the peripheral organs of septic patients. However, very few studies of the possible effects of insulin in cerebral tissues of septic patients have been reported. Therefore, in this study, we aimed to explore whether insulin therapy can inhibit cytokine production (IL-1, IL-6, and TNF-a) and oxidative stress injury of the brain tissue in septic rats. We observed that the protein concentrations of IL-1, IL-6, and TNF-а, in addition to MDA and H₂O₂ were notably increased, inversely SOD, and GSH were sigificantly decreased in cortex, hippocampus, and hypothalamus of septic rats. Furthermore, the levels of S100 and NSE significantly increased. After 6 hours of insulin therapy, we found that the cytokine concentrations notably decreased and oxidative stress injuries in the cortex, hypothalamus, and hippocampus were alleviated in septic rats. In addition, the S100 and NSE levels significantly decreased. We concluded that insulin can inhibit the production of inflammatory cytokines and the oxidative stress response, thereby improving brain tissue damage.

Metabolic implications when employing heavy pre- and post-exercise rapid-acting insulin reductions to prevent hypoglycaemia in type 1 diabetes patients: a randomised clinical trial

Aim

To examine the metabolic, gluco-regulatory-hormonal and inflammatory cytokine responses to large reductions in rapid-acting insulin dose administered prandially before and after intensive running exercise in male type 1 diabetes patients.

Methods

This was a single centre, randomised, controlled open label study. Following preliminary testing, 8 male patients (24±2 years, HbA1c 7.7±0.4%/61±4 mmol.l⁻¹) treated with insulin's glargine and aspart, or lispro attended the laboratory on two mornings at ∼08:00 h and consumed a standardised breakfast carbohydrate bolus (1 g carbohydrate.kg⁻¹BM; 380±10 kcal) and self-administered a 75% reduced rapid-acting insulin dose 60 minutes before 45 minutes of intensive treadmill running at 73.1±0.9% VO_2peak. At 60 minutes post-exercise, patients ingested a meal (1 g carbohydrate.kg⁻¹BM; 660±21 kcal) and administered either a Full or 50% reduced rapid-acting insulin dose. Blood glucose and lactate, serum insulin, cortisol, non-esterified-fatty-acids, β-Hydroxybutyrate, and plasma glucagon, adrenaline, noradrenaline, IL-6, and TNF-α concentrations were measured for 180 minutes post-meal.

Results

All participants were analysed. All glycaemic, metabolic, hormonal, and cytokine responses were similar between conditions up to 60 minutes following exercise. Following the post-exercise meal, serum insulin concentrations were lower under 50% (p<0.05) resulting in 75% of patients experiencing hyperglycaemia (blood glucose ≥8.0 mmol.l⁻¹; 50% n = 6, Full n = 3). β-Hydroxybutyrate concentrations decreased similarly, such that at 180 minutes post-meal concentrations were lower than rest under Full and 50%. IL-6 and TNF-α concentrations remained similar to fasting levels under 50% but declined under Full. Under 50% IL-6 concentrations were inversely related with serum insulin concentrations (r = −0.484, p = 0.017).

Conclusions

Heavily reducing rapid-acting insulin dose with a carbohydrate bolus before, and a meal after intensive running exercise may cause hyperglycaemia, but does not augment ketonaemia, raise inflammatory cytokines TNF-α and IL-6 above fasting levels, or cause other adverse metabolic or hormonal disturbances.

Trial Registration

ClinicalTrials.gov NCT01531855

Monocytes, but not T cells, respond to insulin with Akt(S473) phosphorylation independent of the donor glucometabolic state

BACKGROUND

Obesity is associated with insulin resistance and chronic low-grade inflammation. Insulin has been described to have anti-inflammatory effects in immune cells. Therefore, insulin resistance in immune cells can be expected to have important consequences for immune function. Here, we investigate whether freshly isolated monocytes and T cells, isolated from study subjects with a normal or disturbed glucometabolic state, respond to insulin with phosphorylation of Akt, a key molecule in the insulin signalling pathway.

METHODS

A total of 25 study subjects were enrolled in the study. An oral glucose tolerance test (OGTT) was performed, and from fasting insulin and glucose, the homeostasis model assessment of insulin resistance (HOMA-IR) index was calculated. Peripheral blood mononuclear cells were isolated from heparinized blood and phenotypically characterized by flow cytometry. Basal and insulin-induced fractions of pAkt(S473)-positive monocytes and T cells were determined by Phosflow.

RESULTS

On the basis of the OGTT, 11 subjects were classified as normal glucose tolerant (NGT), 9 had an impaired glucose metabolism (IGM) and 5 had type 2 diabetes (T2DM). The fraction of pAkt(S473)positive-T cells and monocytes, in the absence of insulin, was low in all subjects. Incubation with insulin did not induce Akt phosphorylation in CD4⁺ and CD8⁺ T cells in normal subjects. However, in the monocyte fraction, an insulin-dose-dependent increase of the pAkt(S473)positive-cell fraction was observed. This response did not differ between NGT, IGM and T2DM and was not correlated with HOMA-IR.

CONCLUSIONS

In this study, we show that freshly isolated monocytes, but not T cells, are insulin-sensitive cells and that this insulin sensitivity of monocytes is not negatively affected by the glucometabolic state of the donor.

New insights into insulin: The anti-inflammatory effect and its clinical relevance

Hyperglycemia, a commonly exhibited metabolic disorder in critically ill patients, activates the body’s inflammatory defense mechanism, causing the waterfall release of numerous inflammatory mediators and cytokines, and eventually leads to organ damage. As the only glucose-lowering hormone in the body, insulin not only alleviates the detrimental effects of hyperglycemia through its metabolic regulation, but also directly modulates inflammatory mediators and acts upon immune cells to enhance immunocompetence. In this sense, hyperglycemia is pro-inflammatory whereas insulin is anti-inflammatory. Therefore, during the past 50 years, insulin has not only been used in the treatment of diabetes, but has also been put into practical use in dealing with cardiovascular diseases and critical illnesses. This review summarizes the recent advances regarding the anti-inflammatory effects of insulin in both basic research and clinical trials, with the hope of aiding in the design of further experimental research and promoting effective insulin administration in clinical practice.

Peripheral blood leucocyte subclasses as potential biomarkers of adipose tissue inflammation and obesity subphenotypes in humans

While obesity is clearly accepted as a major risk factor for cardio-metabolic morbidity, it is also apparent that some obese patients largely escape this association, forming a unique obese subphenotype(s). Current approaches to define such subphenotypes include clinical biomarkers that largely reflect already manifested comorbidities, such as markers of dyslipidaemia, hyperglycaemia and impaired regulation of vascular tone, and anthropometric or imaging-based assessment of adipose tissue distribution. Low-grade inflammation, evident both systemically and within adipose tissue (particularly intra-abdominal fat depots), seems to characterize the more cardio-metabolically morbid forms of obesity. Indeed, several systemic inflammatory markers (C-reactive protein), adipokines (retinol-binding protein 4, adiponectin) and cytokines have been shown to correlate in humans with adipose tissue inflammation and with obesity-associated health risks. Circulating leucocytes constitute a diverse group of cells that form a major arm of the immune system. They are both major sources of cytokines and likely also of infiltrating adipose tissue immune cells in obesity. In the present review, we summarize currently available literature on 'classical' blood white cell classes and on more specific leucocyte subclasses present in the circulation in human obesity. We critically raise the possibility that leucocytes may constitute clinically available markers for the more morbidity-associated obesity subphenotype(s), and when available, for intra-abdominal adipose tissue inflammation.

Metabolism of activated T lymphocytes

Activated T cells undergo metabolic reprogramming which promotes glycolytic flux and lactate production as well as elevated production of lipids, proteins, nucleic acids and other carbohydrates (i.e. induction of biomass) even in the presence of oxygen. Activated T cells show induced expression of, among other things, Glucose Transporter 1 and several glycolytic enzymes, including ADP-Dependent Glucokinase and the low affinity isoform Pyruvate Kinase-M2 (which promote glycolytic flux), as well Glutamine Transporters and Glycerol-3-phosphate Dehydrogenase 2 which make available glutamate and glycerol-3-phosphate as mitochondrial energy sources. Intracellular leucine concentrations critically regulate mammalian target of rapamycin (mTOR) signaling to promote Th1, Th2, and Th17 CD4(+) T effector cell differentiation. In contrast, T regulatory (Treg) cells are generated when AMP-Activating Protein Kinase signaling is activated and mTOR activation is suppressed. Unlike effector CD4(+) and CD8(+) T cells, Tregs and memory T cells oxidize fatty acids for fuel. Effector and memory T cells perform different functions and thus show distinct metabolic profiles which are exquisitely controlled by cellular signaling. Upon activation, T cells express the insulin and leptin receptors on their surface and become sensitive to insulin signaling and nutrient availability and show changes in differentiation. Thus, metabolism and nutrient availability influence T cell activation and function.

Obesity and infection: two sides of one coin

The prevalence of obesity has exponentially risen worldwide. The etiology of obesity is multifactorial, and genetic inheritance and behavioral/environmental causes are considered the main etiological factors. Moreover, evidence that specific infections might promote the development of obesity has steadily accumulated. Only a few works investigate the impact of obesity on the immune response to infections and the risk of infections in the obese population. The aim of this paper was to review the available data regarding the various aspects of the association between obesity and infections and to highlight the possibility that infectious agents may have an etiological role in obesity, an idea known as "infectobesity". Several microbes have been considered as possible promoter of obesity, but most of the data concern adenovirus-36 that exerts an adipogenic action mainly via a direct effect on adipose tissue leading to weight gain, at least in animal models.Obesity affects the immune response leading to an increased susceptibility to infections. Obese adults and children show an increased incidence of both nosocomial and community-acquired infections. Furthermore, obesity may alter the pharmacokinetics of antimicrobial drugs and impact on vaccine response. However, the various aspects of the association of obesity infections remain poorly studied, and a call to research is necessary to better investigate the problem.In conclusion, obesity impacts millions globally, and greater understanding of its etiology and its effects on immunity, infections, and prevention and management strategies is a key public health concern.

Insulin and the lung: connecting asthma and metabolic syndrome

Obesity, metabolic syndrome, and asthma are all rapidly increasing globally. Substantial emerging evidence suggests that these three conditions are epidemiologically and mechanistically linked. Since the link between obesity and asthma appears to extend beyond mechanical pulmonary disadvantage, molecular understanding is necessary. Insulin resistance is a strong, independent risk factor for asthma development, but it is unknown whether a direct effect of insulin on the lung is involved. This review summarizes current knowledge regarding the effect of insulin on cellular components of the lung and highlights the molecular consequences of insulin-related metabolic signaling cascades that could adversely affect lung structure and function. Examples include airway smooth muscle proliferation and contractility and regulatory signaling networks that are associated with asthma. These aspects of insulin signaling provide mechanistic insight into the clinical evidence for the links between obesity, metabolic syndrome, and airway diseases, setting the stage for novel therapeutic avenues targeting these conditions.

Insulin signalling mechanisms for triacylglycerol storage

Insulin signalling is uniquely required for storing energy as fat in humans. While de novo synthesis of fatty acids and triacylglycerol occurs mostly in liver, adipose tissue is the primary site for triacylglycerol storage. Insulin signalling mechanisms in adipose tissue that stimulate hydrolysis of circulating triacylglycerol, uptake of the released fatty acids and their conversion to triacylglycerol are poorly understood. New findings include (1) activation of DNA-dependent protein kinase to stimulate upstream stimulatory factor (USF)1/USF2 heterodimers, enhancing the lipogenic transcription factor sterol regulatory element binding protein 1c (SREBP1c); (2) stimulation of fatty acid synthase through AMP kinase modulation; (3) mobilisation of lipid droplet proteins to promote retention of triacylglycerol; and (4) upregulation of a novel carbohydrate response element binding protein β isoform that potently stimulates transcription of lipogenic enzymes. Additionally, insulin signalling through mammalian target of rapamycin to activate transcription and processing of SREBP1c described in liver may apply to adipose tissue. Paradoxically, insulin resistance in obesity and type 2 diabetes is associated with increased triacylglycerol synthesis in liver, while it is decreased in adipose tissue. This and other mysteries about insulin signalling and insulin resistance in adipose tissue make this topic especially fertile for future research.

The impact of hyperglycemic emergencies on the kidney and liver

Studies on the alterations of liver and kidney function parameters in patients with diabetic ketoacidosis (DKA) and diabetic ketosis (DK) were limited. Participants with DKA, DK, non-DK, and healthy controls were enrolled in the current study. Parameters of liver and kidney function were measured and evaluated. The patients with DKA had higher levels of plasma glucose, hemoglobin A1c (HbA1c), uric acid, and creatinine but lower levels of transferases and protein compared with the other three groups (P < 0.05 for all). The patients with DK had higher levels of plasma glucose and HbA1c but lower levels of glutamyl transpeptidase and protein compared with the non-DK and control groups (P < 0.05). Prealbumin levels were significantly reduced in the severe DKA patients compared with the mild/moderate DKA patients. Serum prealbumin levels were correlated with albumin levels (r = 0.401, P = 0.010), HCO3 (r = 0.350, P = 0.027), and arterial pH (r = 0.597, P < 0.001) in the DKA patients. A diagnostic analysis showed that lower prealbumin levels significantly reflected the presence of hyperglycemic emergencies (P < 0.001). Liver and kidney function parameters deteriorated, especially in DKA. Prealbumin levels can be of value in detecting the presence of hyperglycemic crisis. This clinical trial is registered with ChiCTR-OCH-12003077.

Increased serum levels of ischemia-modified albumin and C-reactive protein in type 1 diabetes patients with ketoacidosis

Ischemia-modified albumin (IMA) levels have been advocated as a biomarker for evaluating the oxidative stress status. No data are showed on the potential role of IMA in type 1 diabetes (T1D). We aimed to establish the correlation among serum levels of IMA, C-reactive protein (CRP), and diabetic ketoacidosis (DKA) in patients with T1D. Fifty-seven patients with T1D, 27 patients with DKA, and 40 controls were enrolled. Serum IMA and CRP levels were measured and evaluated to distinguish from DKA. CRP and IMA levels were significantly elevated in patients with DKA at admission to the hospital compared to non-DKA and control subjects. CRP and IMA levels were higher in non-DKA patients than in controls. CRP, plasma glucose, and IMA levels were reduced after insulin treatment. Serum IMA levels were an independent risk marker for DKA (OR = 1.225, p = 0.002, 95 % CI: 1.076-1.394). Receiver operating characteristic curve analyses showed no difference in the areas under curve for serum IMA and CRP values. This study indicates that IMA and CRP levels were significantly correlated with DKA diagnosis. IMA can act as a biomarker that reflects the presence of DKA.

Adaptive immunity in obesity and insulin resistance

Obesity is the hallmark of the metabolic syndrome and predisposes patients to the development of major chronic metabolic diseases including type 2 diabetes mellitus. Adipose tissue expansion in obesity is characterized by increasing infiltration of proinflammatory immune cells into adipose tissue causing chronic, low-grade inflammation. Phenotypic switching of macrophages is an important mechanism of adipose tissue inflammation, and there is involvement of cells from the adaptive immune system in this process. T-cell phenotype changes and recruitment of B cells and T cells precedes macrophage infiltration. Cytokines and chemokines produced by immune cells influence localized and systemic inflammation, which is a pathogenic link between obesity and insulin resistance. Antigens absorbed from the gut might contribute to T-cell activation and recruitment into visceral adipose tissue in obesity. This Review summarizes, in the context of obesity, the evidence for infiltration of adipose tissue by cells of the adaptive immune system, how adaptive system cells affect innate cell populations and the influence of adaptive immune cells on the development of insulin resistance.

Post-admission glucose levels are associated with healthcare-associated bloodstream infections and pneumonia in hospitalized patients with diabetes

OBJECTIVE

We conducted a case-control study to examine if short-term glucose control is related to healthcare-associated bloodstream infections (BSI), urinary tract infections (UTI), and pneumonia in hospitalized adults with diabetes.

SETTING AND PATIENTS

We analyzed 205 BSI, 510 UTI, and 109 pneumonia cases and 989, 2463, and 543 controls matched by age, sex and hospital stay seen at a large healthcare system in Manhattan from 2006 to 2008.

METHODS

We examined whether infection risk was associated with serum glucose measured at admission and within 2 days to infection, using conditional logistic regression. Co-morbidities, immunosuppressive medications, prior hospitalizations, and insertion of indwelling devices were considered as potential confounders.

RESULTS

Admission glucose level was not associated with infection. Glucose levels of ≥ 110 mg/dL measured within 2 days to infection were associated with BSI (Odds ratios from 2.04 to 2.67). Glucose level of ≥ 180 mg/dL was associated with pneumonia (Odds ratio=2.30). Decrease in glucose levels from admission to the infection was greater for controls than for infected cases.

CONCLUSION

Healthcare-associated BSI and pneumonia were associated with glucose levels prior to infection diagnosis, but not with glucose levels at admission. Persistently high glucose level could be an indication of an underlying undiagnosed infection.

Timing of insulin therapy affects the inflammatory response in endotoxemic rats

The aim of the present study was to determine whether timing of insulin administration influences the hepatic and serum proinflammatory and anti-inflammatory cytokines during endotoxemia stimulated by lipopolysaccharide (LPS). Eighty-one male Sprague-Dawley rats were divided into different time groups and insulin was given 30 min pre-LPS administration or hour 0, 1, 3, 6, 12, 24 after the induction of endotoxemia, respectively. Hepatic and serum proinflammatory cytokines IL-1β, IL-6, and TNF-α, and anti-inflammatory cytokine IL-10 were detected 24 and 48 h after the induction of endotoxemia. Compared with sham control rats, serum concentrations of proinflammatory cytokines IL-1β, IL-6, and TNF-α and anti-inflammatory cytokine IL-10 significantly increased on 24 and 48 h after induction of endotoxemia. Similarly, LPS administration also significantly increased the hepatic IL-1β, TNF-α, IL-6, and IL-10 protein concentration 48 h after LPS injection. Compared with levels in positive LPS controls animals receiving saline, on 24 and 48 h after LPS injection, insulin administrated ahead of 6 h after LPS injection significantly decreased the serum IL-1β, IL-6, and TNF-a concentration (P < 0.05), and significantly increased anti-inflammatory cytokine IL-10 concentration (P < 0.05); hepatic IL-1β and IL-6 expression were (P < 0.05) significantly decreased compared with levels in positive LPS controls. But, the significant decrease of hepatic TNF-a expression and significant increase of hepatic IL-10 were only seen in the animals in which insulin was administrated at 30 min pre-LPS or coadministrated with LPS. Insulin administrated 6 h after LPS injection lost the ability to significantly reduce serum or hepatic IL-1β, TNF-α, and IL-6 concentrations. Insulin has a protective role in systemic inflammatory response syndrome related to sepsis, such as downregulation of proinflammatory cytokines and upregulation of anti-inflammatory cytokine production. However, timing of insulin administrated may change its effect of inflammatory response in endotoxemic rats. Insulin administrated 6 h after LPS injection weaken the ability to protect inflammatory response related to sepsis.

Obesity is associated with activated and insulin resistant immune cells

BACKGROUND

Obesity and type 2 diabetes mellitus are characterized by insulin resistance and 'low-grade inflammation'; however, the pathophysiological link is poorly understood. To determine the relative contribution of obesity and insulin resistance to systemic 'inflammation', this study comprehensively characterized circulating immune cells in different grades of obesity.

METHODS

Immune cell phenotypes and activation status were analysed by flow cytometry cross-sectionally in morbidly obese (n = 16, body mass index (BMI) 42.2 ± 5.4 kg/m2), overweight (n = 13, BMI 27.4 ± 1.6 kg/m2) and normal weight (n = 12, BMI 22.5 ± 1.9 kg/m2) subjects.

RESULTS

Obese, but not overweight subjects, had increased activation marker expression on neutrophils, monocytes, T-lymphocytes and polarization of T helper cells towards a pro-inflammatory type 1-phenotype (Th1). Th1 numbers correlated positively with the degree of insulin resistance (homeostasis model assessment, p < 0.05). Lymphocytes from obese subjects showed reduced insulin-stimulated AKT-phosphorylation in vitro. Supra-physiological insulin concentrations did not affect T-cell differentiation, which under normal circumstances would promote an anti-inflammatory T helper type 2-phenotype.

CONCLUSIONS

These results show that morbid obesity is characterized by circulating immune cells that are activated and insulin resistant, with the T-cell balance polarized towards a pro-inflammatory Th1 phenotype. The loss of insulin-induced suppression of inflammatory phenotypes in circulating immune cells could contribute to the systemic and adipose tissue inflammation found in morbid obesity.

The impact of obesity on the immune response to infection

There is strong evidence indicating that excess adiposity negatively impacts immune function and host defence in obese individuals. This is a review of research findings concerning the impact of obesity on the immune response to infection, including a discussion of possible mechanisms. Obesity is characterised by a state of low-grade, chronic inflammation in addition to disturbed levels of circulating nutrients and metabolic hormones. The impact of these metabolic abnormalities on obesity-related comorbidities has undergone intense scrutiny over the past decade. However, relatively little is known of how the immune system and host defence are influenced by the pro-inflammatory and excess energy milieu of the obese. Epidemiological data suggest obese human subjects are at greater risk for nosocomial infections, especially following surgery. Additionally, the significance of altered immunity in obese human subjects is emphasised by recent studies reporting obesity to be an independent risk factor for increased morbidity and mortality following infection with the 2009 pandemic influenza A (H1N1) virus. Rodent models offer important insight into how metabolic abnormalities associated with excess body weight can impair immunity. However, more research is necessary to understand the specific aspects of immunity that are impaired and what factors are contributing to reduced immunocompetence in the obese. Additionally, special consideration of how infection in this at-risk population is managed is required, given that this population may not respond optimally to antimicrobial drugs and vaccination. Obesity impacts millions globally, and greater understanding of its associated physiological disturbances is a key public health concern.

Macrophages, meta-inflammation, and immuno-metabolism

Current research depicts specific modes of immunity and energy metabolism as being interrelated at the molecular, cellular, organ and organism level. Hence, whereas M2 (alternatively-activated) macrophages dominate insulin-sensitive adipose tissue in the lean, M1-skewed (classically-activated) macrophages accumulate in parallel to adiposity in the obese, and promote inflammation and insulin resistance, that is, meta-inflammation. The latest frontier of immuno-metabolism explores the coregulation of energy metabolism and immune function within hematopoietic cells. M1-skewed macrophages are sustained in edematous, hypoxic tissues by anaerobic glycolysis, whereas mitochondrial biogenesis and respiration dominates in M2 cells. We review the underlying mechanisms and the consequences of the transition from M2 to M1 predominance in adipose tissue, as well as the extracellular signals and transcription factors that control macrophage phenotypes and impose distinct metabolic modes.

Beyond the hormone: insulin as an autoimmune target in type 1 diabetes

Insulin is not only the hormone produced by pancreatic β-cells but also a key target antigen of the autoimmune islet destruction leading to type 1 diabetes. Despite cultural biases between the fields of endocrinology and immunology, these two facets should not be regarded separately, but rather harmonized in a unifying picture of diabetes pathogenesis. There is increasing evidence suggesting that metabolic factors (β-cell dysfunction, insulin resistance) and immunological components (inflammation and β-cell-directed adaptive immune responses) may synergize toward islet destruction, with insulin standing at the crossroad of these pathways. This concept further calls for a revision of the classical dichotomy between type 1 and type 2 diabetes because metabolic and immune mechanisms may both contribute to different extents to the development of different forms of diabetes. After providing a background on the mechanisms of β-cell autoimmunity, we will explain the role of insulin and its precursors as target antigens expressed not only by β-cells but also in the thymus. Available knowledge on the autoimmune antibody and T-cell responses against insulin will be summarized. A unifying scheme will be proposed to show how different aspects of insulin biology may lead to β-cell destruction and may be therapeutically exploited. We will argue about possible reasons why insulin remains the mainstay of metabolic control in type 1 diabetes but has so far failed to prevent or halt β-cell autoimmunity as an immune modulatory reagent.

Abdominal fat mass is associated with adaptive immune activation: the CODAM Study

Abdominal fat-related activation of the innate immune system and insulin resistance (IR) are implicated in the pathogenesis of cardiovascular diseases. Recent data support an important role of the adaptive immune system as well. In this study, we investigate the association between waist circumference and markers of systemic adaptive immune activation, and the potential mediating role of innate immune activation and/or IR herein. The study population consisted of 477 (304 men) individuals (mean age: 59.4 ± 7.0 years) in whom waist circumference, HOMA2-IR (IR derived from homeostasis model assessment), and markers of innate (C-reactive protein (CRP), interleukin (IL)-6, serum amyloid A (SAA)) and adaptive (neopterin, soluble CD25 (sCD25)) immune activation were measured. These markers were compiled into an adaptive and innate immune activation score by averaging the respective z-scores. After adjustments for age, sex, glucose metabolism, smoking status, prior cardiovascular disease, and other risk factors, waist circumference was associated with the adaptive (standardized regression coefficient β = 0.12 (95% confidence intervals: 0.04-0.20)) and the innate immune activation scores (β = 0.24 (0.17-0.31)), and with HOMA2-IR (β = 0.49 (0.42-0.56)). The innate immune activation score and HOMA2-IR were also positively associated with the adaptive immune activation score (β = 0.31 (0.21-0.40) and β = 0.11 (0.02-0.21), respectively). The association between waist circumference and the adaptive immune activation score was completely abolished when further adjusted for innate immune activation and HOMA2-IR (to β = -0.01 (-0.10-0.08)), and the specific mediation "effects" attributable to each of these variables were 58% and 42%, respectively. We conclude that abdominal obesity is associated with systemic adaptive immune activation and that innate immune activation and IR constitute independent and equally important pathways explaining this association.

In vivo cytokine modulatory effects of cinnamaldehyde, the major constituent of leaf essential oil from Cinnamomum osmophloeum Kaneh

The purpose of this study was to analyse the major compound in the leaf essential oil of Cinnamomum osmophloeum Kaneh. and to examine its in vivo toxicity and cytokine-modulatory effects. The HS-GC/MS and quantitative HPLC analyses showed the concentrations of the major compounds, cinnamaldehyde, benzaldehyde and 3-phenylpropionaldehyde, in the leaf essential oil of Cinnamomum osmophloeum to be 16.88, 1.28 and 1.70 mg/mL, respectively. Acute and sub-acute toxicity tests identified no significant changes in body weight, liver and kidney function indices, and pathology for the mice treated with up to 1 mL/kg body weight of Cinnamomum osmophloeum leaf essential oil or up to 4 mg/kg body weight of cinnamaldehyde. A murine model was established using ovalbumin (OVA)-primed Balb/C mice treated with various concentrations of Cinnamomum osmophloeum leaf essential oil or cinnamaldehyde daily for 4 weeks. The results of tests with commercial ELISA kits indicated no significant cytokine-modulatory effects in mice treated with Cinnamomum osmophloeum leaf essential oil; however, the serum concentrations of IL-2, IL-4 and IL-10, but not IFN-γ, significantly increased in animals treated with 1 mg/kg body weight of cinnamaldehyde during the 4-week period. The possibility that the other constituents act as antagonists of cinnamaldehyde cannot be excluded.

Cytokine response to diabetic ketoacidosis (DKA) in children with type 1 diabetes (T1DM)

It has been suggested that cytokine release during DKA may result in capillary perturbation and thus may contribute to the development of its acute clinical complications (i.e.cerebral or pulmonary edema). We studied in 38 newly diagnosed T1DM children with DKA, aged 7.68±3.07 years, plasma levels of cytokines IL-1β (interleukin-1β), IL-2, IL-6, IL-8, IL-10, TNF-α (tumour necrosis factor-α) and also WBC (white blood cell count), hs-CRP (high sensitivity C-reactive protein), GH (growth hormone) and cortisol, prior to, during and 120h after DKA management, with the aim to monitor their levels at different time-points and in different degrees of DKA severity. Prior to DKA management the levels of IL-6, IL-8, IL-10, WBC and cortisol were elevated, but were all reduced within 120 h after DKA management. Then the patients were divided into two groups: a. moderate/severe: pH≤7.2, b. mild DKA: pH>7.2. In the group with moderate/severe DKA (ph≤7.2), IL-10 levels were the highest of all cytokines, but were significantly decreased after 6h (91.76 vs 18.04 pg/mL, p=0.008), with no further change, while IL-6 levels were decreased at 120 h (28.32 vs 11.9 pg/mL, p=0.003). The above were not observed in the group with mild DKA. In conclusion, in the children with DKA of our study, in the group with moderate/severe DKA the IL-10 levels were prematurely reduced at 6 hours, while the IL-6 levels remained high and were reduced at 120 hours after the DKA management. These changes may be responsible for increased capillary perturbation, which could lead to the subsequent development of acute DKA complications.

Insulin and metformin may prevent renal injury in young type 2 diabetic Goto-Kakizaki rats

Type 2 diabetes is increasing at epidemic proportions throughout the world, and diabetic nephropathy is the principal cause of end stage renal failure. Approximately 40% of patients with type 2 diabetes may progress to nephropathy and a good metabolic control can prevent the development of diabetic renal injury. The aim of our study was to evaluate, in young type 2 diabetic Goto-Kakizaki (GK) rats fed with atherogenic diet, the effects of the anti-diabetic compounds insulin, metformin and gliclazide on renal damage. GK rats fed with atherogenic diet showed increased body weight and fasting blood glucose, total cholesterol, triglycerides, C-reactive protein and protein carbonyl levels and lower HDL-cholesterol concentration; renal markers of inflammation and fibrosis were also elevated. All the anti-diabetic agents ameliorated fasting glycaemia and insulin resistance but only insulin and metformin were able to improve glycoxidation, fibrosis and inflammation kidney parameters. Our data suggest that insulin and metformin treatments, improving glicoxidative, inflammatory and fibrotic renal damage markers, play a key role in the prevention of diabetic nephropathy.

Isolation and preservation of peripheral blood mononuclear cells for analysis of islet antigen-reactive T cell responses: position statement of the T-Cell Workshop Committee of the Immunology of Diabetes Society

Autoimmune T cell responses directed against insulin-producing β cells are central to the pathogenesis of type 1 diabetes (T1D). Detection of such responses is therefore critical to provide novel biomarkers for T1D 'immune staging' and to understand the mechanisms underlying the disease. While different T cell assays are being developed for these purposes, it is important to optimize and standardize methods for processing human blood samples for these assays. To this end, we review data relevant to critical parameters in peripheral blood mononuclear cell (PBMC) isolation, (cryo)preservation, distribution and usage for detecting antigen-specific T cell responses. Based on these data, we propose recommendations on processing blood samples for T cell assays and identify gaps in knowledge that need to be addressed. These recommendations may be relevant not only for the analysis of T cell responses in autoimmune disease, but also in cancer and infectious disease, particularly in the context of clinical trials.