Biomarkers and immune-modulating therapies for Type 2 diabetes

Exploring the Molecular Mechanism of Comorbidity of Type 2 Diabetes Mellitus and Colorectal Cancer: Insights from Bulk Omics and Single-Cell Sequencing Validation

The relationship between type 2 diabetes mellitus (T2DM) and colorectal cancer (CRC) has long been extensively recognized, but their crosstalk mechanisms based on gene regulation remain elusive. In our study, for the first time, bulk RNA-seq and single-cell RNA-seq data were used to explore the shared molecular mechanisms between T2DM and CRC. Moreover, Connectivity Map and molecular docking were employed to determine potential drugs targeting the candidate targets. Eight genes (EVPL, TACSTD2, SOX4, ETV4, LY6E, MLXIPL, ENTPD3, UGP2) were identified as characteristic comorbidity genes for T2DM and CRC, with EVPL and ENTPD3 further identified as core comorbidity genes. Our results demonstrated that upregulation of EVPL and downregulation of ENTPD3 were intrinsic molecular features throughout T2DM and CRC and were significantly associated with immune responses, immune processes, and abnormal immune landscapes in both diseases. Single-cell analysis highlighted a cancer-associated fibroblast (CAF) subset that specifically expressed ENTPD3 in CRC, which exhibited high heterogeneity and unique tumor-suppressive features that were completely different from classical cancer-promoting CAFs. Furthermore, ENTPD3+ CAFs could notably predict immunotherapy response in CRC, holding promise to be an immunotherapy biomarker at the single-cell level. Finally, we identified that droperidol may be a novel drug simultaneously targeting EVPL and ENTPD3. In conclusion, previous studies have often focused solely on metabolic alterations common to T2DM and CRC. Our study establishes EVPL and ENTPD3 as characteristic molecules and immune biomarkers of comorbidity in T2DM and CRC patients, and emphasizes the importance of considering immunological mechanisms in the co-development of T2DM and CRC.

Identification of Autoantibodies to a Hybrid Insulin Peptide in Type 1 Diabetes

Type 1 diabetes (T1D) is a chronic autoimmune disease that attacks the insulin-producing b cells of the pancreatic islets. Autoantibodies to b cell proteins typically appear in the circulation years before disease onset, and serve as the most accurate biomarkers of T1D risk. Our laboratory has recently discovered novel b cell proteins comprising hybrid proinsulin:islet amyloid polypeptide peptides (IAPP). T cells from a diabetic mouse model and T1D patients are activated by these hybrid peptides. In this study, we asked whether these hybrid molecules could serve as antigens for autoantibodies in T1D and prediabetic patients. We analyzed sera from T1D patients, prediabetics and healthy age-matched donors. Using a highly sensitive electrochemiluminescence assay, sera were screened for binding to recombinant proinsulin:IAPP probes or truncated derivatives. Our results show that sera from T1D patients contain antibodies that bind larger hybrid proinsulin:IAPP probes, but not proinsulin or insulin, at significantly increased frequencies compared to normal donors. Examination of sera from prediabetic patients confirms titers of antibodies to these hybrid probes in more than 80% of individuals, often before seroconversion. These results suggest that hybrid insulin peptides are common autoantigens in T1D and prediabetic patients, and that antibodies to these peptides may serve as valuable early biomarkers of the disease.

Seaweed Derived Lipids Are a Potential Anti-Inflammatory Agent: A Review

Chronic, low-grade inflammation is linked to the development of non-communicable diseases, including cancer, cardiovascular disease, obesity, insulin resistance, diabetes, and others which together contribute to more than 50% of deaths globally. Modulation of inflammatory responses may be a promising strategy, and n-3 long chain polyunsaturated fatty acids (n-3 LC-PUFA) may offer a new therapeutic option in inflammatory conditions. Seaweeds are characterised by high nutritional quality and are a good source of many bioactive compounds, including n-3 LC-PUFA. This review addresses the potential anti-inflammatory properties of seaweed derived lipids, and their immunomodulating mechanisms in order to identify the possible applications of seaweed as an anti-inflammatory functional food ingredient or dietary supplement. A few studies have evaluated the anti-inflammatory activity of seaweed lipids using crude lipid extracts, lipid fractions and isolated complex lipids from several seaweeds belonging to the Ochrophyta and Rhodophyta phyla, with only three Ulva rigida, Ulva sp. and Codium tomentosum within the Chlorophyta phylum. It was reported that seaweed derived lipids suppress inducible nitric oxide synthase and cyclooxygenase-2 expression and reduce nuclear factor κB p100 and myeloid differentiation primary response 88 protein levels leading to the downregulation of the production of several pro-inflammatory cytokines and nitric oxide. Further investigations are required to unravel the complex mechanisms underlying their preventive action against chronic inflammation and their potential use as a new functional food ingredient and/or health supplement.

Type 1 diabetes: what is the role of autoimmunity in β cell death?

The current dogma of type 1 diabetes pathogenesis asserts that an autoimmune attack leads to the destruction of pancreatic β cells, with subsequent hyperglycemia. This dogma is based on islet autoantibodies emerging prior to the onset of type 1 diabetes. In this issue of the JCI, Warncke et al. report on their investigation of the development of hyperglycemia below the diabetes threshold as an early proxy of β cell demise. Surprisingly, they found that an elevation in blood glucose preceded the appearance of autoimmunity. This observation calls into question the importance of autoimmunity as the primary cause of β cell destruction and has implications for prevention and treatment in diabetes.

Neutrophils in pancreatic cancer: Potential therapeutic targets

Pancreatic cancer is a digestive system malignancy and poses a high mortality worldwide. Traditionally, neutrophils have been thought to play a role in acute inflammation. In contrast, their importance during tumor diseases has been less well studied. Generally, neutrophils are recruited into the tumor microenvironment and exert inflammation and tumor-promoting effects. As an essential part of the tumor microenvironment, neutrophils play diverse roles in pancreatic cancer, such as angiogenesis, progression, metastasis and immunosuppression. Additionally, neutrophils can be a new potential therapeutic target in cancer. Inhibitors of cytokines, chemokines and neutrophil extracellular traps can exert antitumor effects. In this review, we describe the role of neutrophils in the development and progression of pancreatic cancer, discuss their potential as therapeutic targets, and aim to provide ideas for improving the prognosis of patients with this malignant tumor disease.

IL-25 Treatment Improves Metabolic Syndrome in High-Fat Diet and Genetic Models of Obesity

INTRODUCTION

Endemic obesity is considered the driving force for the dramatic increase in incidence of type 2 diabetes (T2D). There is mounting evidence that chronic, low-grade inflammation driven by Th1/Th17 cells and M1 macrophages, is a critical link between obesity and insulin resistance. IL-25 promotes development of a Th2 immune response and M2 macrophages that counteract the inflammation associated with obesity and T2D.

METHODS

Mice were fed a high-fat diet (HFD) for 16 weeks and then treated with IL-25 or BSA as a control for 21 days. Body weight, blood glucose levels, intraperitoneal glucose tolerance, and gene expression were evaluated in mice treated with BSA or IL-25. Ob/ob mice fed a normal control diet were also treated with BSA or IL-25 and body weight and blood glucose levels were measured. Transepithelial electrical resistance and sodium-linked glucose absorption were determined in muscle-free small intestinal tissue and glucose absorption assessed in vitro in intestinal epithelial and skeletal muscle cell lines.

RESULTS

Administration of IL-25 to HFD fed mice reversed glucose intolerance, an effect mediated in part by reduction in SGLT-1 activity and Glut2 expression. Importantly, the improved glucose tolerance in HFD mice treated with IL-25 was maintained for several weeks post-treatment indicating long-term changes in glucose metabolism in obese mice. Glucose intolerance was also reversed by IL-25 treatment in genetically obese ob/ob mice without inducing weight loss. In vitro studies demonstrated that glucose absorption was inhibited by IL-25 treatment in the epithelial IPEC-1 cells but increased glucose absorption in the L6 skeletal muscle cells. This supports a direct cell-specific effect of IL-25 on glucose metabolism.

CONCLUSION

These results suggest that the IL-25 pathway may be a useful target for the treatment of metabolic syndrome.

Clinical manifestation and islet β-cell function of a subtype of latent autoimmune diabetes in adults (LADA): positive for T cell responses in phenotypic type 2 diabetes

AIMS

To investigate the possibility of identifying a subtype of latent autoimmune diabetes in adults (LADA), T-LADA (T cell responses-positive and autoantibody-negative) from patients with phenotypic type 2 diabetes (T2D) by enzyme-linked immunospot (ELISPOT).

METHODS

Eighty-two patients with phenotypic T2D were studied. Autoantibodies against glutamic acid decarboxylase (GAD), insulinoma-associated protein-2 and zinc transporter 8 were measured by radioligand assay. Thirty-nine Ab⁺ and 43 Ab^- patients with phenotypic T2D were enrolled for T cell assay of responses to GAD65 and C-peptide antigen by ELISPOT.

RESULTS

(1) Eleven of 43 Ab^- participants with phenotypic T2D were demonstrated interferon (IFN)-γ secreting T cells by ELISPOT, while 13 of 39 Ab⁺ patients with phenotypic T2D were positive for T cells responses to islet antigens. (2) The onset ages of T cell⁺ people with phenotypic T2D were younger than that of T cell^- individuals (42.7 ± 9.3 vs. 48.2 ± 10.2 years, P = 0.025). Moreover, T cell⁺ patients with T2D displayed a significantly lower fasting C-peptide (FCP) compared with T cell^- participants [0.28 (0.02-0.84) vs. 0.42 (0.05-1.26) nmol/L, P = 0.013]. (3) Ab^-T⁺ group had a significantly lower FCP compared with Ab^-T^- group [0.31 (0.13-0.84) vs. 0.51 (0.07-1.26) nmol/L, P = 0.023].

CONCLUSIONS

By measuring T cell responses to islet antigens in patients with phenotypic T2D, we identified a specific subtype of LADA who may be associated with worse basal β-cell function than classic T2D (Ab^-T^-).

The Gut Microbiome Signatures Discriminate Healthy From Pulmonary Tuberculosis Patients

Cross talk occurs between the human gut and the lung through a gut-lung axis involving the gut microbiota. However, the signatures of the human gut microbiota after active Mycobacterium tuberculosis infection have not been fully understood. Here, we investigated changes in the gut microbiota in tuberculosis (TB) patients by shotgun sequencing the gut microbiomes of 31 healthy controls and 46 patients. We observed a dramatic changes in gut microbiota in tuberculosis patients as reflected by significant decreases in species number and microbial diversity. The gut microbiota of TB patients were mostly featured by the striking decrease of short-chain fatty acids (SCFAs)-producingbacteria as well as associated metabolic pathways. A classification model based on the abundance of three species, Haemophilus parainfluenzae, Roseburia inulinivorans, and Roseburia hominis, performed well for discriminating between healthy and diseased patients. Additionally, the healthy and diseased states can be distinguished by SNPs in the species of B. vulgatus. We present a comprehensive profile of changes in the microbiota in clinical TB patients. Our findings will shed light on the design of future diagnoses and treatments for M. tuberculosis infections.

Type 2 Diabetes: How Much of an Autoimmune Disease?

Type 2 diabetes (T2D) is characterized by a progressive status of chronic, low-grade inflammation (LGI) that accompanies the whole trajectory of the disease, from its inception to complication development. Accumulating evidence is disclosing a long list of possible "triggers" of inflammatory responses, many of which are promoted by unhealthy lifestyle choices and advanced age. Diabetic patients show an altered number and function of immune cells, of both innate and acquired immunity. Reactive autoantibodies against islet antigens can be detected in a subpopulation of patients, while emerging data are also suggesting an altered function of specific T lymphocyte populations, including T regulatory (Treg) cells. These observations led to the hypothesis that part of the inflammatory response mounting in T2D is attributable to an autoimmune phenomenon. Here, we review recent data supporting this framework, with a specific focus on both tissue resident and circulating Treg populations. We also propose that selective interception (or expansion) of T cell subsets could be an alternative avenue to dampen inappropriate inflammatory responses without compromising immune responses.

The genetic architecture of type 1 diabetes mellitus

Type 1 diabetes mellitus (T1D) is a complex autoimmune disorder characterised by loss of the insulin-producing pancreatic beta cells in genetically predisposed individuals, ultimately resulting in insulin deficiency and hyperglycaemia. T1D is most common among children and young adults, and the incidence is on the rise across the world. The aetiology of T1D is hypothesized to involve genetic and environmental factors that result in the T-cell mediated destruction of pancreatic beta cells. There is a strong genetic risk to T1D; with genome-wide association studies (GWAS) identifying over 60 susceptibility regions within the human genome which are marked by single nucleotide polymorphisms (SNPs). Here, we review what is currently known about the genetics of T1D. We argue that advancing our understanding of the aetiology and pathogenesis of T1D will require the integration of genome biology (omics-data) with GWAS data, thereby making it possible to elucidate the putative gene regulatory networks modulated by disease-associated SNPs. This approach has a potential to revolutionize clinical management of T1D in an era of precision medicine.

Intratumoural leukocyte infiltration is a prognostic indicator among pancreatic cancer patients with type 2 diabetes

BACKGROUND

The life expectancy of pancreatic cancer patients remains minimal. The disease progression may be influenced by type 2 diabetes (T2D) and inflammatory status, although important gaps persist around their joint effects on disease outcome. The aim of this study was to investigate the clinical significance of the tumour immune microenvironment on pancreatic cancer prognosis in relation to T2D status.

METHOD

Tumour-infiltrating macrophages, neutrophils and eosinophils were studied in primary pancreatic tumours and paired lymph node metastases in relation to patient and tumour characteristics, T2D status and overall survival in a retrospective cohort of patients with resectable pancreatic cancer in Sweden.

RESULTS

Of the 80 included pancreatic cancer patients, 22 (27.2%) had T2D. The diabetic pancreatic cancer patients had significantly higher systemic high white blood cell count than those without diabetes (P = 0.028). Macrophage infiltration levels were higher in lymph node metastases compared with primary tumours (P = 0.040) among pancreatic cancer patients with diabetes. Type 2 diabetes or intra-tumoural leukocyte (macrophage, neutrophil or eosinophil) infiltration alone did not significantly influence pancreatic cancer prognosis. However, among cancer patients with T2D high macrophage or neutrophil tumour-infiltration was associated with a significant reduction in overall survival (adjusted hazard ratio [HR] 7.2; 95% CI 1.5-35.0 and HR 5.4; 95% CI 1.1-26.3, respectively).

CONCLUSION

These results demonstrate associations between T2D and enhanced inflammatory processes with significant implications on survival among pancreatic cancer patients with T2D. Validation in larger independent patient cohorts may identify additional prognostic tools and improved treatment strategies for specific patient subsets.

Functional role of natural killer T cells in non-obese pre-diabetes model mice

Pre-diabetic patients have a high risk of developing diabetes as well as other associated diseases. From the viewpoint of risk assessment and to assist the development of protective therapies, we focused on the functional role of natural killer T (NKT) cells in pre-diabetes. We found that the expression of an NKT cell marker gene, Va14-Ja18, was significantly lower in specific tissues/organs such as adipose tissue and pancreas in non-obese pre-diabetes model mice than in their normal littermates. Subsequently, in the pre-diabetes model mice, Va14-Ja18 was activated with α-galactosylceramide (α-GalCer) and its effect on glucose tolerance was estimated. The simultaneous injection of α-GalCer and lymphocytes improved glucose tolerance with its maximum effect on the 3rd day. An analysis of circulating cytokine levels revealed that interferon-γ, which is a pro-inflammatory cytokine, was secreted only on the 1st day after treatment with α-GalCer and that interleukin (IL)-4, which is an anti-inflammatory cytokine, was secreted from the 1st to the 4th day. The prolonged secretion of IL-4 was thought to substantially contribute to the improvement of glucose tolerance. Based on these results, the functional role of NKT cells in pre-diabetes is to improve metabolic dysfunctions.

Autoantibodies against PFDN2 are associated with an increased risk of type 2 diabetes: A case-control study

BACKGROUND

The adaptive immune system is involved in type 2 diabetes mellitus (T2DM), indicating the presence of unidentified autoantibodies that might be useful biomarkers for emerging immunomodulatory therapy. A prior microarray study with a small number of participants suggested the association of novel autoantibodies with T2DM in Southwest American Indians. We therefore sought to determine whether antibodies against 14 target proteins are associated with T2DM in a large case-control study.

METHODS

Participants were adults (age 20-59 y) of Southwest American Indian heritage. Plasma antibodies against 14 possible target proteins were measured in 476 cases with T2DM of less than 5 years duration and compared with 424 controls with normal glucose regulation.

RESULTS

Higher levels of antibodies against prefoldin subunit 2 (PFDN2) were associated with T2DM (P = .0001; Bonferroni-corrected threshold for multiple tests = 0.0036 [α = 0.05]). The association between anti-PFDN2 antibodies and T2DM remained in multivariable logistic regression (odds ratio 1.27; 95% confidence interval, 1.09-1.49; per one SD difference in anti-PFDN2 antibody). The odds of T2DM were increased in the highest anti-PFDN2 antibody quintile by 66% compared with the lowest quintile. Differences in anti-PFDN2 antibodies were most prominent among cases with earlier onset of disease (ie, age 20-39 y) compared with controls.

CONCLUSIONS

Anti-PFDN2 antibodies are associated with T2DM and might be a useful biomarker. These findings indicate that autoimmunity may play a role in T2DM in Southwest American Indians, especially among adults presenting with young onset of disease.

Dietary Anthocyanins against Obesity and Inflammation

Chronic low-grade inflammation plays a pivotal role in the pathogenesis of obesity, due to its associated chronic diseases such as type II diabetes, cardiovascular diseases, pulmonary diseases and cancer. Thus, targeting inflammation is an attractive strategy to counter the burden of obesity-induced health problems. Recently, food-derived bioactive compounds have been spotlighted as a regulator against various chronic diseases due to their low toxicity, as opposed to drugs that induce severe side effects. Here we describe the beneficial effects of dietary anthocyanins on obesity-induced metabolic disorders and inflammation. Red cabbage microgreen, blueberry, blackcurrant, mulberry, cherry, black elderberry, black soybean, chokeberry and jaboticaba peel contain a variety of anthocyanins including cyanidins, delphinidins, malvidins, pelargonidins, peonidins and petunidins, and have been reported to alter both metabolic markers and inflammatory markers in cells, animals, and humans. This review discusses the interplay between inflammation and obesity, and their subsequent regulation via the use of dietary anthocyanins, suggesting an alternative dietary strategy to ameliorate obesity and obesity associated chronic diseases.

Identification of Unique Antigenic Determinants in the Amino Terminus of IA-2 (ICA512) in Childhood and Adult Autoimmune Diabetes: New Biomarker Development

OBJECTIVE

The characterization of diverse subtypes of diabetes is a dynamic field of clinical research and an active area of discussion. The objective of this study was to identify new antigenic determinants in the neuroendocrine autoantigen IA-2 (ICA512) and assess whether circulating autoantibodies directed to new IA-2 epitopes identify autoimmune diabetes in young and adult populations with diabetes.

RESEARCH DESIGN AND METHODS

Clinically diagnosed patients with type 2 diabetes (n = 258; diabetes duration: 0.01-31 years) were evaluated using a new biomarker detecting autoantibodies directed to the extracellular domain of the neuroendocrine autoantigen IA-2 (IA-2ec). The proportion of IA-2ec autoantibodies was also evaluated in newly diagnosed patients with type 1 diabetes (n = 150; diabetes duration: 0.04-0.49 years). In addition, IA-2 (intracellular domain), GAD65, and zinc transporter 8 autoantibodies were assayed.

RESULTS

IA-2ec autoantibodies were detected in patients with type 1 diabetes and, surprisingly, in 5% of patients with type 2 diabetes without serologic responses to other IA-2 antigenic epitopes or other islet autoantigens. We also assessed the ability of IA-2ec-derived peptides to elicit CD4⁺ T-cell responses by stimulating peripheral blood mononuclear cells from patients with type 1 diabetes (n = 18) and HLA-matched healthy subjects (n = 13) with peptides and staining with the peptide/DQ8-specific tetramers, observing disease-associated responses to previously unreported epitopes within IA-2ec.

CONCLUSIONS

We developed a new antibody biomarker identifying novel antigenic determinants within the N terminus of IA-2. IA-2ec autoantibodies can be detected in patients with type 1 diabetes and in a subgroup of adult autoimmune patients with type 2 diabetes phenotype negative for conventional islet autoantibody testing. These observations suggest that islet autoimmunity may be more common in clinically diagnosed type 2 diabetes than previously observed.

Weissella cibaria WIKIM28 ameliorates atopic dermatitis-like skin lesions by inducing tolerogenic dendritic cells and regulatory T cells in BALB/c mice

The occurrence of atopic dermatitis (AD), a chronic inflammatory skin disease, has been increasing steadily in children and adults in recent decades. In this study, we evaluated the ability of the lactic acid bacterium Weissella cibaria WIKIM28 isolated from gatkimchi, a Korean fermented vegetable preparation made from mustard leaves, to suppress the development of AD induced by 2,4-dinitrochlorobenzene in a murine model. Oral administration of W. cibaria WIKIM28 reduced AD-like skin lesions, epidermal thickening, and serum immunoglobulin E levels. Furthermore, the production of type 2 helper T (Th2) cytokines such as interleukin (IL)-4, IL-5, and IL-13 decreased in peripheral lymph node cells. Moreover, the intake of W. cibaria WIKIM28 increased the proportion of CD4⁺CD25⁺Foxp3⁺ regulatory T (Treg) cells in mesenteric lymph nodes (MLNs) and IL-10 levels in polyclonally stimulated MLN cells. In conclusion, the oral administration of W. cibaria WIKIM28 isolated from gatkimchi ameliorated AD-like symptoms by suppressing allergic Th2 responses and inducing Treg responses. These results suggest that W. cibaria WIKIM28 may be applicable as a probiotic for the prevention and amelioration of AD.

Interleukin 2 Topical Cream for Treatment of Diabetic Foot Ulcer: Experiment Protocol

Background

It is estimated there are 2.9 million diabetic patients in the United Kingdom, and around 5%-7% of patients have diabetic ulcers. This number will continue to increase globally. Diabetic ulcers are a major economic burden on the healthcare system. More than £650 million is spent on foot ulcers or amputations each year, and up to 100 people a week have a limb amputated due to diabetes. In T1DM, the level of IL-2 is reduced, and hence, wound healing is in a prolonged inflammatory phase. It is not known if IL-2 topical cream can shorten the healing process in T1DM patients.

Objective

The objective of this study is to understand the pathophysiology in type 1 diabetes (T1DM) and investigate possible future treatment based on its clinical features. The hypothesis is that IL-2 cream can speed up wound healing in NOD mice and that this can be demonstrated in a ten-week study. An experiment protocol is designed in a mouse model for others to conduct the experiment. The discussion is purely based on diabetic conditions; lifestyle influences like smoking and drinking are not considered.

Methods

Skin incisions will be created on 20 nonobese diabetic (NOD) mice, and IL-2 topical cream will be applied in a 10-week study to prove the hypothesis. Mice will be randomly and equally divide into two groups with one being the control group.

Results

T1DM patients have a decreased number of T regulatory (Treg) cells and interleukin 2 (IL-2). These are the keys to the disease progression and delay in wound healing. Diabetic ulcer is a chronic wound and characterized by a prolonged inflammatory phase.

Conclusions

If the experiment is successful, T1DM patients will have an alternative, noninvasive treatment of foot ulcers. In theory, patients with other autoimmune diseases could also use IL-2 topical cream for treatment.

Immuno-metabolism and adipose tissue: The key role of hematopoietic stem cells

The field of immunometabolism has come a long way in the past decade, leading to the emergence of a new role for white adipose tissue (WAT) that is now recognized to stand at the junction of immune and metabolic regulations. Interestingly, a crucial role of the abundant and heterogeneous immune population present in WAT has been proposed in the induction and development of metabolic diseases. Although a large body of data focused on mature immune cells, only few scattered studies are dedicated to leukocyte production, and the activity of hematopoietic stem cells (HSC) in these pathological states. Considering that blood cell production and the differentiation of HSCs and their progeny is orchestrated, in part, by complex interacting signals emanating from their microenvironment, it thus seems worth to better understand the relationships between metabolism and HSC. This review discusses the alterations of hematopoietic process described in metabolic diseases and focused on the emerging data concerning HSC present in WAT.

Biomarkers of insulin sensitivity and insulin resistance: Past, present and future

Insulin resistance in insulin target tissues including liver, skeletal muscle and adipose tissue is an early step in the progression towards type 2 diabetes. Accurate diagnostic parameters reflective of insulin resistance are essential. Longstanding tests for fasting blood glucose and HbA1c are useful and although the hyperinsulinemic euglycemic clamp remains a "gold standard" for accurately determining insulin resistance, it cannot be implemented on a routine basis. The study of adipokines, and more recently myokines and hepatokines, as potential biomarkers for insulin sensitivity is now an attractive and relatively straightforward approach. This review discusses potential biomarkers including adiponectin, RBP4, chemerin, A-FABP, FGF21, fetuin-A, myostatin, IL-6, and irisin, all of which may play significant roles in determining insulin sensitivity. We also review potential future directions of new biological markers for measuring insulin resistance, including metabolomics and gut microbiome. Collectively, these approaches will provide clinicians with the tools for more accurate, and perhaps personalized, diagnosis of insulin resistance.

Something old, something new and something very old: drugs for treating type 2 diabetes

Diabetes mellitus belongs to the most rapidly increasing diseases worldwide. Approximately 90-95% of these patients suffer from type 2 diabetes mellitus, which is characterized by peripheral insulin resistance and the progressive loss of beta-cell function and mass. Considering the complications of this chronic disease, a reliable anti-diabetic treatment is indispensable. An ideal oral anti-diabetic drug should not only correct glucose homeostasis but also preserve or even augment beta-cell function and mass, ameliorate the subclinical inflammation present under insulin-resistant conditions and prevent the macro- and microvascular consequences of diabetes in order to reduce the mortality. Despite the many anti-diabetic drugs already in use, there is an ongoing research for additional drugs, guided by different concepts of the pathogenesis of type 2 diabetes. This review will briefly summarize current oral anti-diabetic drugs. In addition, emerging strategies for the treatment of diabetes will be described, among them the inhibition of glucagon action and anti-inflammatory drugs. Their suitability as 'ideal anti-diabetic drugs' will be discussed.

What is the role of autoimmunity in type 1 diabetes? A clinical perspective

Despite tremendous research efforts, type 1 diabetes is one of the few remaining autoimmune diseases without any approved immunological treatment. This observation compels us to reconsider the role of autoimmunity in the pathogenesis of this disease. In this commentary, we will review solely human data in an attempt to appreciate, in an unbiased manner, the importance and relevance of the immunological alterations in patients with type 1 diabetes. The aim of this paper is to generate reflection on this topic, rather than a controversy.

Type 2 diabetes mellitus--an autoimmune disease?

Inflammation-induced inhibition of the insulin signalling pathway can lead to insulin resistance and contribute to the development of type 2 diabetes mellitus (T2DM). Obesity and insulin resistance are associated with a chronic but subclinical inflammatory process that impairs insulin action in most tissues and could also hamper pancreatic β-cell function. The involvement of monocytic cells and the profiles of the chemokines and cytokines induced by this inflammation suggest an innate immune response. However, emerging data indicate that elements of the adaptive immune system could also be involved. As activation of an adaptive response requires antigen specificity, some researchers have hypothesized that T2DM evolves from an innate immune response to an autoimmune condition. In this Perspectives article, we present the arguments for and against this hypothesis and discuss which mechanisms could be involved in a putative switch from innate immunity to autoimmunity.

The immune system as a sensor of the metabolic state

Mammals possess a remarkable ability to maintain and defend a constant internal milieu against diverse environmental threats. Unsurprisingly, the two systems tasked with these duties, metabolism and immunity, have evolved to share a common modular architecture that allows extensive bidirectional communication and coordination. Indeed, recent observations have highlighted numerous functionally critical immune regulatory modules located within diverse metabolic circuits. In this review, we discuss the architectural commonality between immunity and metabolism and highlight how these two primordially disparate systems leverage shared regulatory axes to coordinate metabolic physiology under conditions of normality and chronic overnutrition. Such an integrated perspective both advances our understanding of basic physiology and highlights potential opportunities for therapeutic intervention in metabolic dysfunction.

Probiotics can generate FoxP3 T-cell responses in the small intestine and simultaneously inducing CD4 and CD8 T cell activation in the large intestine

Most studies on probiotics aim to restore intestinal homeostasis to reduce immune-pathology in disease. Of equal importance are studies on how probiotics might prevent or delay disease in healthy individuals. However, knowledge on mechanisms of probiotic actions in healthy individuals is scarce. To gain more insight in how different bacterial strains may modulate the healthy intestinal immune system, we investigated the effect of the food derived bacterial strains L. plantarum WCFS1, L. salivarius UCC118, and L. lactis MG1363, on the intestinal regulatory immune phenotype in healthy mice. All three bacterial strains induced an upregulation of activity and numbers of CD11c⁺ MHCII⁺ DCs in the immune-sampling Peyer’s Patches. Only L. salivarius UCC118 skewed towards an immune regulatory phenotype in the small intestinal lamina propria (SILP). The effects were different in the large intestine lamina propria. L. salivarius UCC118 induced activation in both CD4 and CD8 positive T-cells while L. plantarum WCFS1 induced a more regulatory phenotype. Moreover, L. plantarum WCFS1 decreased the Th1/Th2 ratio in the SILP. Also L. lactis MG1363 had immunomodulatory effects. L. lactis MG1363 decreased the expression of the GATA-3 and T-bet in the SILP. As our data show that contradictory effects may occur in different parts of the gut, it is recommended to study effects of probiotic in different sites in the intestine. Our strain-specific results suggest that unspecified application of probiotics may not be very effective. Our data also indicate that selection of specific probiotic strain activities on the basis of responses in healthy mice may be a promising strategy to specifically stimulate or suppress immunity in specific parts of the intestine.

Islet inflammation: a unifying target for diabetes treatment?

In the past decade, islet inflammation has emerged as a contributor to the loss of functional β cell mass in both type 1 (T1D) and type 2 diabetes (T2D). Evidence supports the idea that overnutrition and insulin resistance result in the production of proinflammatory mediators by β cells. In addition to compromising β cell function and survival, cytokines may recruit macrophages into islets, thus augmenting inflammation. Limited but intriguing data imply a role of adaptive immune response in islet dysfunction in T2D. Clinical trials have validated anti-inflammatory therapies in T2D, whereas immune therapy for T1D remains challenging. Further research is required to improve our understanding of islet inflammatory pathways and to identify more effective therapeutic targets for T1D and T2D.

Autoantibody repertoires, natural biomarkers, and system controllers

The immune system is composed of networks of interacting cells and molecules; therefore, to understand and control immune behavior we need to adopt the thinking and tools of systems immunology. This review describes the use of an antigen microarray device and informatics to profile the repertoires of autoantibodies in health and disease. Autoantibody profiling provides an insight into the biomarkers used by the immune system in its dialog with the body. Heat shock protein 60 (HSP60) and HSP70 are cited as examples of key hubs in physiological regulatory networks; HSP molecules and peptides can be viewed as natural regulators because the immune system itself deploys them to modulate inflammatory reactions. The discovery of such natural biomarkers paves the way towards natural control.

Chronic adipose tissue inflammation: all immune cells on the stage

Inflammation is indispensable for host homeostasis against invading pathogens and efficient wound healing upon tissue malfunction and has to be tightly controlled by various mechanisms to limit excess responses harmful to host tissues. A myriad of disease conditions ranging from type 2 diabetes (T2D) to neurodegenerative and cardiovascular disorders are now shown to progress due to persistent, unresolved inflammation in metabolic tissues such as adipose, liver, pancreas, muscle, and brain. However, their underlying mechanisms are incompletely understood. The actions of innate and adaptive immune cells in these ailments are increasingly appreciated so much so that a new research area called 'immunometabolism' has emerged. In this review, we will highlight the fundamental roles of various immune cells in adipose tissue during the initiation and progression of obesity-induced inflammation and discuss potential anti-inflammatory therapies from different mechanistic points of view.

Genome-scale modeling of human metabolism - a systems biology approach

Altered metabolism is linked to the appearance of various human diseases and a better understanding of disease-associated metabolic changes may lead to the identification of novel prognostic biomarkers and the development of new therapies. Genome-scale metabolic models (GEMs) have been employed for studying human metabolism in a systematic manner, as well as for understanding complex human diseases. In the past decade, such metabolic models - one of the fundamental aspects of systems biology - have started contributing to the understanding of the mechanistic relationship between genotype and phenotype. In this review, we focus on the construction of the Human Metabolic Reaction database, the generation of healthy cell type- and cancer-specific GEMs using different procedures, and the potential applications of these developments in the study of human metabolism and in the identification of metabolic changes associated with various disorders. We further examine how in silico genome-scale reconstructions can be employed to simulate metabolic flux distributions and how high-throughput omics data can be analyzed in a context-dependent fashion. Insights yielded from this mechanistic modeling approach can be used for identifying new therapeutic agents and drug targets as well as for the discovery of novel biomarkers. Finally, recent advancements in genome-scale modeling and the future challenge of developing a model of whole-body metabolism are presented. The emergent contribution of GEMs to personalized and translational medicine is also discussed.

Attenuation of islet-specific T cell responses is associated with C-peptide improvement in autoimmune type 2 diabetes patients

The clinical efficacy of peroxisome proliferator-activated receptor gamma (PPAR-γ) agonists in cell-mediated autoimmune diseases results from down-regulation of inflammatory cytokines and autoimmune effector cells. T cell islet autoimmunity has been demonstrated to be common in patients with phenotypic type 2 diabetes mellitus (T2DM) and islet-specific T cells (T(+) ) to be correlated positively with more severe beta cell dysfunction. We hypothesized that the beneficial effects of the PPAR-γ agonist, rosiglitazone, therapy in autoimmune T2DM patients is due, in part, to the immunosuppressive properties on the islet-specific T cell responses. Twenty-six phenotypic T2DM patients positive for T cell islet autoimmunity (T(+) ) were identified and randomized to rosiglitazone (n = 12) or glyburide (n = 14). Beta cell function, islet-specific T cell responses, interleukin (IL)-12 and interferon (IFN)-γ responses and islet autoantibodies were followed for 36 months. Patients treated with rosiglitazone demonstrated significant (P < 0·03) down-regulation of islet-specific T cell responses, although no change in response to tetanus, a significant decrease (P < 0·05) in IFN-γ production and significantly (P < 0·001) increased levels of adiponectin compared to glyburide-treated patients. Glucagon-stimulated beta cell function was observed to improve significantly (P < 0·05) in the rosiglitazone-treated T2DM patients coinciding with the down-regulation of the islet-specific T cell responses. In contrast, beta cell function in the glyburide-treated T2DM patients was observed to drop progressively throughout the study. Our results suggest that down-regulation of islet-specific T cell autoimmunity through anti-inflammatory therapy may help to improve beta cell function in autoimmune phenotypic T2DM patients.

L. plantarum, L. salivarius, and L. lactis attenuate Th2 responses and increase Treg frequencies in healthy mice in a strain dependent manner

Many studies on probiotics are aimed at restoring immune homeostasis in patients to prevent disease recurrence or reduce immune-mediated pathology. Of equal interest is the use of probiotics in sub-clinical situations, which are characterized by reduced immune function or low-grade inflammation, with an increased risk of infection or disease as a consequence. Most mechanistic studies focus on the use of probiotics in experimental disease models, which may not be informative for these sub-clinical conditions. To gain better understanding of the effects in the healthy situation, we investigated the immunomodulatory effects of two Lactobacillus probiotic strains, i.e. L. plantarum WCFS1 and L. salivarius UCC118, and a non-probiotic lactococcus strain, i.e. L. lactis MG1363, in healthy mice. We studied the effect of these bacteria on the systemic adaptive immune system after 5 days of administration. Only L. plantarum induced an increase in regulatory CD103⁺ DC and regulatory T cell frequencies in the spleen. However, all three bacterial strains, including L. lactis, reduced specific splenic T helper cell cytokine responses after ex vivo restimulation. The effect on IFN-γ, IL5, IL10, and IL17 production by CD4⁺ and CD8⁺ T cells was dependent on the strain administered. A shared observation was that all three bacterial strains reduced T helper 2 cell frequencies. We demonstrate that systemic immunomodulation is not only observed after treatment with probiotic organisms, but also after treatment with non-probiotic bacteria. Our data demonstrate that in healthy mice, lactobacilli can balance T cell immunity in favor of a more regulatory status, via both regulatory T cell dependent and independent mechanisms in a strain dependent manner.