Isabella Spagnuolo

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

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.

Oral Delivery of Glutamic Acid Decarboxylase (GAD)-65 and IL10 by Lactococcus lactis Reverses Diabetes in Recent-Onset NOD Mice

Growing insight into the pathogenesis of type 1 diabetes (T1D) and numerous studies in preclinical models highlight the potential of antigen-specific approaches to restore tolerance efficiently and safely. Oral administration of protein antigens is a preferred method for tolerance induction, but degradation during gastrointestinal passage can impede such protein-based therapies, reducing their efficacy and making them cost-ineffective. To overcome these limitations, we generated a tolerogenic bacterial delivery technology based on live Lactococcus lactis (LL) bacteria for controlled secretion of the T1D autoantigen GAD65370–575 and the anti-inflammatory cytokine interleukin-10 in the gut. In combination with short-course low-dose anti-CD3, this treatment stabilized insulitis, preserved functional β-cell mass, and restored normoglycemia in recent-onset NOD mice, even when hyperglycemia was severe at diagnosis. Combination therapy did not eliminate pathogenic effector T cells, but increased the presence of functional CD4+Foxp3+CD25+ regulatory T cells. These preclinical data indicate a great therapeutic potential of orally administered autoantigen-secreting LL for tolerance induction in T1D.

Innate immunity and the pathogenesis of type 1 diabetes

Type 1 diabetes mellitus is an autoimmune disease caused by the immune-mediated destruction of insulin-producing pancreatic beta cells occurring in genetically predisposed individuals, with consequent hyperglycemia and serious chronic complications. Studies in man and in experimental animal models have shown that both innate and adaptive immune responses participate to disease pathogenesis, possibly reflecting the multifactorial pathogenetic nature of this autoimmune disorder, with the likely involvement of environmental factors occurring at least in a subset of individuals. As a consequence, components of both innate and adaptive immune response should be considered as potential targets of therapeutic strategies for disease prevention and cure. Here we review the contribution of innate immune response to type 1 diabetes, with a particular emphasis to Toll-like receptors (TLR) and NK cells.

Immunology in the clinic review series; focus on type 1 diabetes and viruses: how viral infections modulate beta cell function

OTHER THEMES PUBLISHED IN THIS IMMUNOLOGY IN THE CLINIC REVIEW SERIES

Dietary supplementation with high doses of regular vitamin D3 safely reduces diabetes incidence in nod mice when given early and long-term

High doses of the active form of vitamin D3, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], prevent diabetes in the NOD mouse but also elicit unwanted calcemic side effects. Because immune cells themselves can convert vitamin D3 into 1,25(OH)2D3 locally, we hypothesized that dietary vitamin D3 can also prevent disease. Thus, we evaluated whether dietary administration of high doses of regular vitamin D3 (800 IU/day) during different periods of life (pregnancy and lactation, early life [3–14 weeks of age], or lifelong [3–35 weeks of age]) safely prevents diabetes in NOD mice. We found that only lifelong treatment raised serum 25-hydroxyvitamin D3 from 173 nmol/L in controls to 290 nmol/L, without inducing signs of calcemic or bone toxicity, and significantly reduced diabetes development in both male and female NOD mice. This diabetes protection by vitamin D3 correlated with preserved pancreatic insulin content and improved insulitis scores. Moreover, vitamin D3 treatment decreased interferon-γ–positive CD8+ T cells and increased CD4+(CD25+)FoxP3+ T cells in pancreatic draining lymph nodes. In conclusion, this study shows for the first time that high doses of regular dietary vitamin D3 can safely prevent diabetes in NOD mice when administered lifelong, although caution is warranted with regards to administering equivalently high doses in humans.

Detection of four diabetes specific autoantibodies in a single radioimmunoassay: an innovative high-throughput approach for autoimmune diabetes screening

Highly sensitive and specific radioimmunoassays have been validated for autoantibodies reacting with the four major autoantigens identified so far in autoimmune diabetes. However, the analysis of this large number of autoantigens has increased the costs and time necessary for complete autoantibody screenings. Our aim was to demonstrate that it is possible to detect the immunoreactivity against a combination of four different autoantigens by a single assay, this representing a rapid, low‐cost first approach to evaluate humoral autoimmunity in diabetes. By using this novel multi‐autoantigen radioimmunoassay (MAA), in subsequent steps we analysed 830 sera, 476 of known and 354 of unknown diabetes‐specific immunoreactivity, collected from various groups of individuals including type 1 and type 2 diabetes patients, autoantibody‐positive patients with a clinical diagnosis of type 2 diabetes (LADA), prediabetic subjects, individuals at risk to develop autoimmune diabetes, siblings of type 1 diabetic patients, coeliac patients and healthy control subjects. All sera reacting with one or more of the four autoantigens by single assays also resulted positive with MAA, as well as eight of 24 type 1 diabetic patients classified initially as autoantibody‐negative at disease onset based on single autoantibody assays. In addition, MAA showed 92% sensitivity and 99% specificity by analysing 140 blinded sera from type 1 diabetic patients and control subjects provided in the 2010 Diabetes Autoantibody Standardization Program. MAA is the first combined method also able to evaluate, in addition to glutamic acid decarboxylase (GAD) and tyrosine phosphatase (IA)‐2, insulin and islet beta‐cell zinc cation efflux transporter (ZnT8) autoantibodies. It appears to be particularly appropriate as a first‐line approach for large‐scale population‐based screenings of anti‐islet autoimmunity.

Viral Infections and Diabetes

Type 1 diabetes mellitus (T1DM) is a multi-factorial autoimmune disease determined by the interaction of genetic, environmental and immunologic factors. One of the environmental risk factors identified by a series of independent studies is represented by viral infection, with strong evidence showing that viruses can indeed infect pancreatic beta cells with consequent effects ranging from functional damage to cell death. In this chapter we review the data obtained both in man and in experimental animal models in support of the potential participation of viral infections to Type 1 diabetes pathogenesis, with a particular emphasis on virus-triggered islet inflammation, beta-cell dysfunction and autoimmunity.

The case for virus-induced type 1 diabetes.

Purpose of review Type 1 diabetes (T1D) results from the immune-mediated destruction of pancreatic insulin-producing cells because of the interaction among genetic susceptibility, the immune system and environmental factor(s). A possible role of viral infections in T1D pathogenesis has been hypothesized for some time; however, only in the most recent years, studies performed at the molecular and cellular level are starting to shed light on this issue. Recent findings Studies in animal models and in man have shown that viruses can indeed infect pancreatic beta-cells, inducing islet inflammation and functional damage. In addition, recent in-situ investigations performed on pancreatic tissue samples have provided evidence that in addition to adaptive immune response, innate immunity is involved in T1D pathogenesis and the whole pancreas (not only its endocrine portion) is infiltrated by immune-mediated phenomena. Summary The established role of inflammation in the insulitic process and the increasing evidence in support of the contribution of viral infections to a proinflammatory islet scenario are strongly suggestive that viruses may indeed contribute to beta-cell damage and dysfunction, thus setting the stage for the design of antiviral strategies (e.g. vaccines and antiviral drugs) aimed at protecting the beta-cells.

Delta-cell-specific expression of hedgehog pathway Ptch1 receptor in murine and human endocrine pancreas

Hedgehog pathway plays an important role during pancreas development, when its inactivation is crucial to assure expression of pancreatic marker genes involved in the organ formation and to assure an appropriate organogenesis. Patched1 (Ptch1) is a transmembrane receptor of hedgehog pathway which has a key role in this process. In fact, heterozygous Ptch1 mutant (ptc+/−) mice are affected by an impaired glucose tolerance accompanied by reduced islet function. In the light that the cell distribution of Ptch1 receptor within the endocrine pancreas has not yet been established, we aimed at identifying the pancreatic endocrine cell subset(s) expressing such molecule.

Coxsackieviruses and Insulitis

Coxsackievirus infections are believed to be a relevant risk factor in the induction of pancreatic beta cell damage and autoimmune response in type 1 diabetes mellitus. Genomic RNA and proteins of coxsackieviruses have been detected in tissues of type 1 diabetes patients, supporting the involvement of enteroviruses in the pathogenesis of type 1 diabetes. Coxsackieviruses may infect beta cells, trigger the activation of innate immune systems, or accelerate the autoimmune process leading to the disease. Local inflammatory changes generated in pancreatic islets and the mechanisms leading to its generation and progression have been studied in animal models of type 1 diabetes and in humans. The role of coxsackieviruses in the insulitic process is discussed in this chapter, together with the ability of selected coxsackievirus serotypes to protect against type 1 diabetes.