Immunology of type 1 diabetes

Insulin protects against type 1 diabetes mellitus-induced aortopathy associated with the inhibition of biomarkers of vascular injury in rats

BACKGROUND

We sought to investigate the protective effect of insulin against type 1 diabetes mellitus (T1DM)-induced aortic injury (aortopathy) associated with the inhibition of biomarkers of vascular injury.

MATERIAL AND METHODS

T1DM was induced in rats by streptozotocin (STZ) (65 mg/kg), and the protection group started insulin treatment 2 days post diabetic induction and continued until being sacrificed at week 8.

RESULTS

Aortopathy was developed in the diabetic rats as demonstrated by profound alterations to the aorta ultrastructure, which was substantially protected by insulin. In addition, insulin significantly inhibited diabetes-induced dyslipidaemia, soluble vascular cell adhesion molecule-1 (sVCAM-1) and soluble intercellular adhesion molecule-1 (sICAM-1), oxidative stress, and inflammation. However, blood levels of these biomarkers in the insulin-treated group were still significant (p < .05) compared with the control group, whereas insulin treatment returned blood glucose and triglyceride to control levels.

CONCLUSIONS

We demonstrate effective protection by insulin against T1DM-induced aortopathy in rats, which is associated with the inhibition of vascular injury biomarkers.

The evaluation of cytokines to help establish diagnosis and guide treatment of autoinflammatory and autoimmune diseases

Our knowledge of the role of cytokines in pathologic conditions has increased considerably with the emergence of molecular and genetic studies, particularly in the case of autoinflammatory monogenic diseases. Many rare disorders, considered orphan until recently, are directly related to abnormal gene regulation, and the treatment with biologic agents (biologics) targeting cytokine receptors, intracellular signaling or specific cytokines improve the symptoms of an increasing number of chronic inflammatory diseases. As it is currently impossible to systematically conduct genetic studies for all patients with autoinflammatory and autoimmune diseases, the evaluation of cytokines can be seen as a simple, less time consuming, and less expensive alternative. This approach could be especially useful when the diagnosis of syndromes of diseases of unknown etiology remains problematic. The evaluation of cytokines could also help avoid the current trial-and-error approach, which has the disadvantages of exposing patients to ineffective drugs with possible unnecessary side effects and permanent organ damages. In this review, we discuss the various possibilities, as well as the limitations of evaluating the cytokine profiles of patients suffering from autoinflammatory and autoimmune diseases, with methods such as direct detection of cytokines in the plasma/serum or following ex vivo stimulation of PBMCs leading to the production of their cytokine secretome. The patients' secretome, combined with biomarkers ranging from genetic and epigenetic analyses to immunologic biomarkers, may help not only the diagnosis but also guide the choice of biologics for more efficient and rapid treatments.

Immunological Impacts of Diabetes on the Susceptibility of Mycobacterium tuberculosis

The interaction between diabetes and major world infections like TB is a major public health concern because of rapidly rising levels of diabetes. The dual burden of tuberculosis (TB) and diabetes mellitus (DM) has become a major global public health problem. Diabetes mellitus is a major risk factor for the development of active and latent tuberculosis. Immune mechanisms contributing to the increased susceptibility of diabetic patients to TB are due to the defects in bacterial recognition, phagocytic activity, and cellular activation which results in impaired production of chemokines and cytokines. The initiation of adaptive immunity is delayed by impaired antigen-presenting cell (APC) recruitment and function in hyperglycemic host, which results in reduced frequencies of Th1, Th2, and Th17 cells and its secretion of cytokines having a great role in activation of macrophage and inflammatory response of tuberculosis. In addition, impaired immune response and killing of intracellular bacteria potentially increase bacterial load, chronic inflammation, and central necrosis that facilitate bacterial dissemination and miliary tuberculosis. Understanding of the immunological and biochemical basis of TB susceptibility in diabetic patients will tell us the rational development of implementation and therapeutic strategies to alleviate the dual burden of the diseases. Therefore, the aim of this review was focused on the association between diabetes and tuberculosis, focusing on epidemiology, pathogenesis, and immune dysfunction in diabetes mellitus, and its association with susceptibility, severity, and treatment outcome failure to tuberculosis.

Comparative Analysis of the Transcriptome of Latent Autoimmune Diabetes in Adult (LADA) Patients from Eastern China

Latent autoimmune diabetes in adults (LADA) is characterized as a slow-progressing form of autoimmune diabetes. LADA resembles some phenotypes of type 1 diabetes (T1D) and type 2 diabetes (T2D), frequently leading to misdiagnosis and inappropriate therapeutic strategies. Understanding its transcriptome profiles aids in revealing the detailed molecular mechanisms of LADA and its therapy. In the present study, we performed RNA-seq analysis of LADA patients from Eastern China and showed that LADA exhibited 277 differentially expressed genes (DEGs) with 199 upregulated and 78 downregulated. Gene ontology and KEGG pathway enrichment analysis revealed that these DEGs were mainly related to immune function and cell death and growth. Furthermore, a comparison of DEGs in LADA with those in T1D and T2D identified from the online databases showed that there are very few overlapped genes between LADA and T1D or T2D, confirming LADA to be a distinct type of diabetes from T1D or T2D. In summary, our comprehensive analysis may aid in the understanding and treatment of LADA patients in Eastern China.

Insulin and vanadium protect against osteoarthritis development secondary to diabetes mellitus in rats

OBJECTIVE

Diabetic complications such as cardiovascular disease and osteoarthritis (OA) are among the common public health problems. The effect of insulin on OA secondary to diabetes has not been investigated before in animal models. Therefore, we sought to determine whether insulin and the insulin-mimicking agent, vanadium can protect from developing OA in diabetic rats.

METHODS

Type 1 diabetes mellitus (T1DM) was induced in Sprague-Dawley rats and treated with insulin and/or vanadium. Tissues harvested from the articular cartilage of the knee joint were examined by scanning electron microscopy, and blood samples were assayed for oxidative stress and inflammatory biomarkers.

RESULTS

Eight weeks following the induction of diabetes, a profound damage to the knee joint compared to the control non-diabetic group was observed. Treatment of diabetic rats with insulin and/or vanadium differentially protected from diabetes-induced cartilage damage and deteriorated fibrils of collagen fibers. The relative biological potencies were insulin + vanadium >> insulin > vanadium. Furthermore, there was about 2- to 5-fold increase in TNF-α (from 31.02 ± 1.92 to 60.5 ± 1.18 pg/ml, p < 0.0001) and IL-6 (from 64.67 ± 8.16 to 338.0 ± 38.9 pg/ml, p < 0.0001) cytokines and free radicals measured as TBARS (from 3.21 ± 0.37 to 11.48 ± 1.5 µM, p < 0.0001) in the diabetic group, which was significantly reduced with insulin and or vanadium. Meanwhile, SOD decreased (from 17.79 ± 8.9 to 8.250.29, p < 0.0001) and was increased with insulin and vanadium. The relative potencies of the treating agents on inflammatory and oxidative stress biomarkers were insulin + vanadium >> insulin > vanadium.

CONCLUSION

The present study demonstrates that co-administration of insulin and vanadium to T1DM rats protect against diabetes-induced OA possibly by lowering biomarkers of inflammation and oxidative stress.

Evaluation of fetal cell transplantation safety in treatment of diabetes: a three-year follow-up

Background

Rapidly increasing prevalence of diabetes throughout the world highlights the importance of looking for new treatment options for the disease such as stem cell therapy. With regard to the increasing attention towards stem-cell therapy as a curative treatment for diabetes in recent years, it is of crucial importance to ensure the safety of this novel therapeutic technique. In this study we aim to evaluate the safety of fetal liver-derived cell suspension allotransplantation in the diabetic patients who had attended a clinical trial in 2007.

Methods

44 out of a total number of 56 patients who had undergone either fetal liver-derived cell suspension allotransplantation or placebo injection in 2007 (IRCT number: 138811071414 N10) were contacted and recruited for the evaluation of possible complications. Patients were referred to a designated ophthalmologist and cardiologist to be screened for retinopathy and cardiovascular diseases. 24-hour urine was collected and tested for the evaluation of nephropathy; and, neuropathy was assessed by means of neuropathic symptoms and monofilament test.

Results

There were no life-threatening complications nor significant differences in terms of evaluated diabetes complications ( retinopathy, neuropathy, nephropathy and cardiovascular diseases ) between the case and control groups. However, one case of meningioma was reported.

Conclusions

Findings of our study demonstrated that stem cell transplantation can be considered a relatively safe procedure apart from one case of meningioma; it did neither cause any life-threatening complications nor increased the rate of the diabetes micro- and macrovascular complications.

Assessment of CD4+ T cell responses to glutamic acid decarboxylase 65 using DQ8 tetramers reveals a pathogenic role of GAD65 121-140 and GAD65 250-266 in T1D development

Susceptibility to type 1 diabetes (T1D) is strongly associated with MHC class II molecules, particularly HLA-DQ8 (DQ8: DQA1*03:01/DQB1*03:02). Monitoring T1D-specific T cell responses to DQ8-restricted epitopes may be key to understanding the immunopathology of the disease. In this study, we examined DQ8-restricted T cell responses to glutamic acid decarboxylase 65 (GAD65) using DQ8 tetramers. We demonstrated that GAD65 121-140 and GAD65 250-266 elicited responses from DQ8+ subjects. Circulating CD4+ T cells specific for these epitopes were detected significantly more often in T1D patients than in healthy individuals after in vitro expansion. T cell clones specific for GAD65 121-140 and GAD65 250-266 carried a Th1-dominant phenotype, with some of the GAD65 121-140-specific T cell clones producing IL-17. GAD65 250-266-specific CD4+ T cells could also be detected by direct ex vivo staining. Analysis of unmanipulated peripheral blood mononuclear cells (PBMCs) revealed that GAD65 250-266-specific T cells could be found in both healthy and diabetic individuals but the frequencies of specific T cells were higher in subjects with type 1 diabetes. Taken together, our results suggest a proinflammatory role for T cells specific for DQ8-restricted GAD65 121-140 and GAD65 250-266 epitopes and implicate their possible contribution to the progression of T1D.

Compromised central tolerance of ICA69 induces multiple organ autoimmunity

For reasons not fully understood, patients with an organ-specific autoimmune disease have increased risks of developing autoimmune responses against other organs/tissues. We identified ICA69, a known β-cell autoantigen in Type 1 diabetes, as a potential common target in multi-organ autoimmunity. NOD mice immunized with ICA69 polypeptides exhibited exacerbated inflammation not only in the islets, but also in the salivary glands. To further investigate ICA69 autoimmunity, two genetically modified mouse lines were generated to modulate thymic ICA69 expression: the heterozygous ICA69(del/wt) line and the thymic medullary epithelial cell-specific deletion Aire-ΔICA69 line. Suboptimal central negative selection of ICA69-reactive T-cells was observed in both lines. Aire-ΔICA69 mice spontaneously developed coincident autoimmune responses to the pancreas, the salivary glands, the thyroid, and the stomach. Our findings establish a direct link between compromised thymic ICA69 expression and autoimmunity against multiple ICA69-expressing organs, and identify a potential novel mechanism for the development of multi-organ autoimmune diseases.

Chlorinated persistent organic pollutants, obesity, and type 2 diabetes

Persistent organic pollutants (POPs) are lipophilic compounds that travel with lipids and accumulate mainly in adipose tissue. Recent human evidence links low-dose POPs to an increased risk of type 2 diabetes (T2D). Because humans are contaminated by POP mixtures and POPs possibly have nonmonotonic dose-response relations with T2D, critical methodological issues arise in evaluating human findings. This review summarizes epidemiological results on chlorinated POPs and T2D, and relevant experimental evidence. It also discusses how features of POPs can affect inferences in humans. The evidence as a whole suggests that, rather than a few individual POPs, background exposure to POP mixtures-including organochlorine pesticides and polychlorinated biphenyls-can increase T2D risk in humans. Inconsistent statistical significance for individual POPs may arise due to distributional differences in POP mixtures among populations. Differences in the observed shape of the dose-response curves among human studies may reflect an inverted U-shaped association secondary to mitochondrial dysfunction or endocrine disruption. Finally, we examine the relationship between POPs and obesity. There is evidence in animal studies that low-dose POP mixtures are obesogenic. However, relationships between POPs and obesity in humans have been inconsistent. Adipose tissue plays a dual role of promoting T2D and providing a relatively safe place to store POPs. Large prospective studies with serial measurements of a broad range of POPs, adiposity, and clinically relevant biomarkers are needed to disentangle the interrelationships among POPs, obesity, and the development of T2D. Also needed are laboratory experiments that more closely mimic real-world POP doses, mixtures, and exposure duration in humans.

Role of immune system in type 1 diabetes mellitus pathogenesis

The immune system is the body's natural defense system against invading pathogens. It protects the body from infection and works to communicate an individual's well-being through a complex network of interconnected cells and cytokines. This system is an associated host defense. An uncontrolled immune system has the potential to trigger negative complications in the host. Type 1 diabetes results from the destruction of pancreatic β-cells by a β-cell-specific autoimmune process. Examples of β-cell autoantigens are insulin, glutamic acid decarboxylase, tyrosine phosphatase, and insulinoma antigen. There are many autoimmune diseases, but type 1 diabetes mellitus is one of the well-characterized autoimmune diseases. The mechanisms involved in the β-cell destruction are still not clear; it is generally believed that β-cell autoantigens, macrophages, dendritic cells, B lymphocytes, and T lymphocytes are involved in the β-cell-specific autoimmune process. It is necessary to determine what exact factors are causing the immune system to become unregulated in such a manner as to promote an autoimmune response.

Increased expression of microRNA miR-326 in type 1 diabetic patients with ongoing islet autoimmunity

BACKGROUND

The current paradigm that microRNAs represent a new layer of gene regulation has generated much interest in this field. MicroRNAs have emerged as important regulatory factors involved in the developmental processes and in the regulation of insulin secretion and signalling. Furthermore, recent studies revealed an altered microRNA profiling in lymphocytes of patients with autoimmune diseases like multiple sclerosis, in which a hyperexpression of miR-326 was reported. Here, we analysed the expression levels of miR-326 in peripheral blood lymphocytes from type 1 diabetic (T1D) patients in relationship with ongoing islet autoimmunity.

METHODS

Peripheral blood lymphocytes were obtained from 19 T1D patients; 4/19 patients were positive for both glutamic acid decarboxylase (GAD) and islet cell antigen 512 autoantibodies; 10/19 were single GAD or IA-2 Ab positive and 5/19 were GAD antibodies and IA-2 antibodies (IA-2A) negative. Quantitative analysis of miR-326 was performed using specific stem-loop primers followed by real-time polymerase chain reaction. All values were normalized to endogenous control U6.

RESULTS

miR-326 resulted increased in Ab-positive versus Ab-negative T1D subjects. Its expression levels were 2.05±0.38-fold increased in peripheral blood lymphocytes from patients expressing both GADA and IA-2A and 2.93±0.46-fold increased in single Ab-positive versus Ab-negative individuals (p<0.05).

CONCLUSION

In conclusion, we have shown that miR-326 is expressed at higher levels in T1D subjects with ongoing islet autoimmunity, similar to what has been observed in multiple sclerosis, in which levels of this microRNA were highly correlated with disease severity. Interestingly, an online search of miR-326 predicted targets revealed vitamin D receptor and Erythroblastosis virus E26 oncogene homologue 1, two molecules highly involved in immune regulation.

The multi-systemic nature of diabetes mellitus: Genotype or phenotype?

BACKGROUND

This article discusses factors which materially influence the diagnosis, prevention and treatment of diabetes mellitus but which may be overlooked by the prevailing biomedical paradigm. That cognition can be mathematically linked to the function of the autonomic nervous system and physiological systems casts new light upon the mechanisms responsible for homeostasis and origins of disease. In particular, it highlights the limitations of the reductionist biomedical approach which considers mainly the biochemistry of single pathologies rather than considering the neural mechanisms which regulate the function of physiological systems, and inherent visceral organs; and which are subsequently manifest as biochemistries of varying degrees of complexity and severity. As a consequence, histopathological tests are fraught with inherent limitations and many categories of drugs are significantly ineffective.

AIMS

Such limitations may be explained if disease (in particular diabetes mellitus) has multiple origins, is multi-systemic in nature and, depending upon the characteristics of each pathology, is influenced by genotype and/or phenotype.

RESULTS

This article highlights the influence of factors which are not yet considered re. the aetiology of diabetes mellitus e.g. the influence of light and sensory input upon the stability of the autonomic nervous system; the influence of raised plasma viscosity upon rates of reaction; the influence of viruses and/or of modified live viruses given in vaccinations; systemic instability, in particular the adverse influence of drinks and lack of exercise upon the body's prevailing pH and its subsequent influence upon levels of magnesium and other essential trace elements.

CONCLUSIONS

This application of the top-down systems biology approach may provide a plausible and inclusive explanation for the nature and occurrence of diabetes mellitus.

Mathematical modelling of immune regulation of type 1 diabetes

Type 1 diabetes is a disease characterized by progressive loss of β cell function due to an autoimmune reaction affecting the islets of Langerhans. Two types of T cells are involved in diabetes: turncoat auto-reactive T cells, or T cells gone bad, that kill the insulin-producing cells, and regulatory T cells that are unable to control the auto-reactive T cells. We formulate a mathematical model that incorporates the role of cytotoxic T cells and regulatory T cells in type 1 diabetes. This study shows that onset of type 1 diabetes is due to a collective, dynamical instability, rather than being caused by a single etiological factor. It is also a numbers game between regulatory T cells and auto-reactive T cells. The problem in the onset of this disease is that there are not enough of the regulatory cells that suppress the immune response against the body's insulin-producing pancreatic islet cells.

Autoimmune diabetes in adults: lessons from the UKPDS

Latent autoimmune diabetes in adults (LADA) is characterised by a relatively mild diabetes onset, autoantibody positivity and eventual requirement for insulin therapy. Twelve per cent of newly diagnosed, UK Prospective Diabetes Study (UKPDS) patients were positive for autoantibodies to GAD65 (GADA) and/or insulinoma-associated antigen-2A (IA-2A) and managed as if they had Type 2 diabetes according to the UKPDS protocol. Here, we compare data from UKPDS LADA patients with that from other cohorts. In common with other groups, UKPDS LADA patients required insulin therapy earlier post-diagnosis than non-LADA patients. Reduction of islet function was similar in UKPDS LADA groups randomised to oral glucose-lowering agents or insulin replacement therapy, contesting the current hypothesis of reduced decline of insulin secretion in LADA by immediate insulin therapy. Disease progression was not predicted by post-diagnosis GADA levels or epitope specificities as has been suggested. Slowly progressing insulitis and pancreatic beta-cell loss at post-mortem are consistent with sustained retention of residual C-peptide secretion in LADA. Genetic association patterns at the human leucocyte antigen (HLA) and insulin gene (INS) regions are similar in UKPDS LADA patients and individuals with adult and childhood-onset Type 1 diabetes. The combined evidence suggests that LADA is an adult-onset form of Type 1 diabetes, rather than a separate condition or an intermediate state in a continuum of phenotype from Type 1 to Type 2 diabetes.

Understanding diseases by mouse click: the promise and potential of computational approaches in Systems Biology

Computational modelling approaches can nowadays build large-scale simulations of cellular behaviour based on data describing detailed molecular level interactions, thus performing the space- and time-scale integrations that would be impossible just by intuition. Recent progress in the development of both experimental methods and computational tools has provided the means to generate the necessary quantitative data and has made computational methods accessible even to non-theorists, thereby removing a major hurdle that has in the past made many experimentalists hesitate to invest serious effort in formulating quantitative models. We describe how computational biology differs from classical bioinformatics, how it emerged from mathematical biology and elucidate the role it plays for the integration of traditionally separated areas of biomedical research within the larger framework of Systems Biology.

Effect of interferon alpha on MHC class II gene expression in ex vivo human islet tissue

Type 1 diabetes (T1D) is caused by autoimmune destruction of the insulin-producing beta-cells of the islets of Langerhans. One still open question is where naive islet-reactive T cells encounter antigens and become stimulated. In this report we have re-examined the expression of MHC class II (MHCII) genes in human islets to further explore the possibility that non-professional antigen presenting cells (APCs) within islets contribute to autoimmunity. Since development of T1D has been linked to viral infections, we also studied ex-vivo MHCII expression in response to interferon-alpha (IFNalpha) in islet tissue and in different APCs. The findings are: first, MHCII genes expression in human islets is linked with the expression of the class II transactivator isoform transcribed from the promoter IV, similar to that described in non-professional APCs. Second, there is IFNalpha-mediated lineage-specific regulation of MHCII genes expression, seen as a decrease in the accumulation of MHCII transcripts in pancreatic islets opposite to an increase in dendritic cells and B-lymphoblastoid cell lines. Third, there is allele-specific regulation of the HLA-DQA1 gene by IFNalpha in islet tissue. These findings may begin to explain the molecular events that create favorable conditions for organ-specific autoimmunity and explain the incomplete penetrance of T1D susceptibility alleles.