Immunology in the clinic review series; focus on type 1 diabetes and viruses: the enterovirus link to type 1 diabetes: critical review of human studies

Targeting β Cells with Cathelicidin Nanomedicines Improves Insulin Function and Pancreas Regeneration in Type 1 Diabetic Rats

Type 1 diabetes (T1D) is an incurable condition with an increasing incidence worldwide, in which the hallmark is the autoimmune destruction of pancreatic insulin-producing β cells. Cathelicidin-based peptides have been shown to improve β cell function and neogenesis and may thus be relevant while developing T1D therapeutics. In this work, a cathelicidin-derived peptide, LLKKK18, was loaded in poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs), surface-functionalized with exenatide toward a GLP-1 receptor, aiming the β cell-targeted delivery of the peptide. The NPs present a mean size of around 100 nm and showed long-term stability, narrow size distribution, and negative ζ-potential (-10 mV). The LLKKK18 association efficiency and loading were 62 and 2.9%, respectively, presenting slow and sustained in vitro release under simulated physiologic fluids. Glucose-stimulated insulin release in the INS-1E cell line was observed in the presence of the peptide. In addition, NPs showed a strong association with β cells from isolated rat islets. After administration to diabetic rats, NPs induced a significant reduction of the hyperglycemic state, an improvement in the pancreatic insulin content, and glucose tolerance. Also remarkable, a considerable increase in the β cell mass in the pancreas was observed. Overall, this novel and versatile nanomedicine showed glucoregulatory ability and can pave the way for the development of a new generation of therapeutic approaches for T1D treatment.

LncRNA ARGI Contributes to Virus-Induced Pancreatic β Cell Inflammation Through Transcriptional Activation of IFN-Stimulated Genes

Type 1 diabetes (T1D) is a complex autoimmune disease that develops in genetically susceptible individuals. Most T1D-associated single nucleotide polymorphisms (SNPs) are located in non-coding regions of the human genome. Interestingly, SNPs in long non-coding RNAs (lncRNAs) may result in the disruption of their secondary structure, affecting their function, and in turn, the expression of potentially pathogenic pathways. In the present work, the function of a virus-induced T1D-associated lncRNA named ARGI (Antiviral Response Gene Inducer) is characterized. Upon a viral insult, ARGI is upregulated in the nuclei of pancreatic β cells and binds to CTCF to interact with the promoter and enhancer regions of IFNβ and interferon-stimulated genes, promoting their transcriptional activation in an allele-specific manner. The presence of the T1D risk allele in ARGI induces a change in its secondary structure. Interestingly, the T1D risk genotype induces hyperactivation of type I IFN response in pancreatic β cells, an expression signature that is present in the pancreas of T1D patients. These data shed light on the molecular mechanisms by which T1D-related SNPs in lncRNAs influence pathogenesis at the pancreatic β cell level and opens the door for the development of therapeutic strategies based on lncRNA modulation to delay or avoid pancreatic β cell inflammation in T1D.

Stress and Diabetes Mellitus: Pathogenetic Mechanisms and Clinical Outcome

Evidence suggests that psychological and physical stress are relevant triggering factors for the onset of type 1 diabetes (T1D) and type 2 diabetes (T2D). The underlying mechanisms involve a complex neuroendocrine structure, involving the central nervous system and the periphery. Psychological stress leads to an increase of serum glucocorticoid concentrations and catecholamines release increasing the insulin need and the insulin resistance. According to the β-cell stress hypothesis, also causes of increased insulin demand, such as rapid growth, overweight, puberty, low physical activity, trauma, infections, and glucose overload, are potentially relevant factors in development of T1D. It has also been demonstrated that chronic stress and obesity form a vicious circle which leads to a definitive metabolic failure, increasing the risk of developing T2D. In this review, we will provide the most recent data concerning the role of stress in the outcomes of T1D and T2D, with a focus on the role of physical and psychological stress on the onset of T1D.

Month of birth and the risk of developing type 1 diabetes among children in the Swedish national Better Diabetes Diagnosis Study

AIM

Previous studies have reported an association between month of birth and incidence of type 1 diabetes. Using population-based data, including almost all newly diagnosed children with type 1 diabetes in Sweden, we tested whether month of birth influences the risk of type 1 diabetes.

METHODS

For 8761 children diagnosed with type 1 diabetes between May 2005 and December 2016 in the Better Diabetes Diagnosis study, month of birth, sex and age were compared. Human leucocyte antigen (HLA) genotype and autoantibodies at diagnosis were analysed for a subset of the cohort (n = 3647). Comparisons with the general population used data from Statistics Sweden.

RESULTS

We found no association between month of birth or season and the incidence of type 1 diabetes in the cohort as a whole. However, boys diagnosed before 5 years were more often born in May (p = 0.004). We found no correlation between month of birth and HLA or antibodies.

CONCLUSION

In this large nationwide study, the impact of month of birth on type 1 diabetes diagnosis was weak, except for boys diagnosed before 5 years of age, who were more likely born in May. This may suggest different triggers for different subgroups of patients with type 1 diabetes.

Molecular Mimicry, Hyperactive Immune System, And SARS-COV-2 Are Three Prerequisites of the Autoimmune Disease Triangle Following COVID-19 Infection

SARS-CoV-2 infection can produce a variety of clinical manifestations, which are either directly related to viral tissue damage or indirectly induced by the antiviral immune response. Molecular mimicry enables this virus to undermine self-tolerance in a host's immune system also immune system's attempts to eliminate SARS-COV-2 may trigger autoimmunity by hyper-activating the innate and adaptive immune systems. Auto immune diseases include Systemic lupus erythematosus, autoimmune thyroid diseases, Guillain‐Barre syndrome, Immune thrombocytopenic purpura, and the detection of autoantibodies are the cues to the discovery of the potential of COVID‐19 in inducing autoimmunity. As COVID-19 and autoimmune diseases share a common pathogenesis, autoimmune drugs may be an effective treatment option. Susceptible patients must be monitored for autoimmune symptoms after contracting CVID-19. In light of the SARS-COV-2 virus' ability to induce autoimmunity in susceptible patients, will the various COVID-19 vaccines that are the only way to end the pandemic induce autoimmunity?

Enteroviruses and Type 1 Diabetes: Multiple Mechanisms and Factors?

Type 1 diabetes (T1D) is a chronic autoimmune disease characterized by insulin deficiency and resultant hyperglycemia. Complex interactions of genetic and environmental factors trigger the onset of autoimmune mechanisms responsible for development of autoimmunity to β cell antigens and subsequent development of T1D. A potential role of virus infections has long been hypothesized, and growing evidence continues to implicate enteroviruses as the most probable triggering viruses. Recent studies have strengthened the association between enteroviruses and development of autoimmunity in T1D patients, potentially through persistent infections. Enterovirus infections may contribute to different stages of disease development. We review data from both human cohort studies and experimental research exploring the potential roles and molecular mechanisms by which enterovirus infections can impact disease outcome.

Enteroviruses and Type 1 Diabetes: Multiple Mechanisms and Factors?

Type 1 diabetes (T1D) is a chronic autoimmune disease characterized by insulin deficiency and resultant hyperglycemia. Complex interactions of genetic and environmental factors trigger the onset of autoimmune mechanisms responsible for development of autoimmunity to β cell antigens and subsequent development of T1D. A potential role of virus infections has long been hypothesized, and growing evidence continues to implicate enteroviruses as the most probable triggering viruses. Recent studies have strengthened the association between enteroviruses and development of autoimmunity in T1D patients, potentially through persistent infections. Enterovirus infections may contribute to different stages of disease development. We review data from both human cohort studies and experimental research exploring the potential roles and molecular mechanisms by which enterovirus infections can impact disease outcome.

Autoimmune complications of COVID-19

Coronavirus disease 2019 (COVID-19) is still propagating a year after the start of the pandemic. Besides the complications patients face during the COVID-19 disease period, there is an accumulating body of evidence concerning the late-onset complications of COVID-19, of which autoimmune manifestations have attracted remarkable attention from the first months of the pandemic. Autoimmune hemolytic anemia, immune thrombocytopenic purpura, autoimmune thyroid diseases, Kawasaki disease, Guillain-Barre syndrome, and the detection of autoantibodies are the cues to the discovery of the potential of COVID-19 in inducing autoimmunity. Clarification of the pathophysiology of COVID-19 injuries to the host, whether it is direct viral injury or autoimmunity, could help to develop appropriate treatment.

Possible Association of Pulmonary Atresia with In-Utero Coxsackievirus B Exposure

Gestational viral infection has been associated with congenital heart disease (CHD). Few studies, however, have studied the potential role of gestational Coxsackievirus B (CVB) exposure in the pathogenesis of CHD. We prospectively enrolled women with pregnancies affected by CHD to explore possible associations with in utero CVB exposure. Serum samples were obtained from 122 women referred for fetal echocardiography between 2006 and 2018. We quantified CVB IgG and IgM levels, with titers ≥ 15.0 U/mL considered positive and measured neutralizing antibodies for three CVB serotypes: CVB1, CVB3, and CVB4. Using data from the national enterovirus surveillance system, we compared the annual exposure rates for each serotype in our cohort to infections reported across the United States. 98 pregnancies with no genetic defects were included. Overall, 29.6% (29/98) had positive IgG and 4.1% (4/98) of women had positive CVB IgM titers. To explore first-trimester CVB exposure, we focused exclusively on the 26 women with positive IgG and negative IgM titers. 61.5% (16/26) had neutralizing antibodies against a single serotype and 38.5% (10/26) against multiple CVB serotypes. CVB4 neutralizing antibodies were the most common (65.4%, 17/26), followed by CVB3 (53.9%, 14/26) and CVB1 (30.8%, 8/26). Among these, 30.8% of babies presented pulmonary valve anomalies: 19.2% (5/26) pulmonary atresia, and 11.5% (3/26) pulmonary stenosis. 23.1% (6/26) of babies had coronary sinusoids. CVB exposure in our cohort mirrored that of reported infections in the United States. Our results suggest a possible association between gestational CVB exposure and specific CHD, particularly pulmonary valve anomalies and coronary sinusoids.

Rola autoimmunizacji w rozwoju powikłań cukrzycowych – przegląd badań

Przewlekłe powikłania cukrzycy są główną przyczyną obniżenia jakości życia, niepełnosprawności, a nawet przedwczesnej śmierci pacjentów cierpiących na tę chorobę. Mimo istotnego postępu w dziedzinie farmakoterapii, ich leczenie pozostaje nadal wyzwaniem w codziennej praktyce klinicznej. Brak terapii przyczynowej wynika z niewystarczającego zrozumienia molekularnych mechanizmów uszkadzających poszczególne narządy w cukrzycy. Uważa się, że etiopatogeneza tych powikłań jest złożona i zależy od czynników genetycznych i środowiskowych. W ich rozwoju, oprócz zaburzeń metabolicznych związanych z hiperglikemią, nasilenia stresu oksydacyjnego, dysfunkcji śródbłonka, indukcji stanu zapalnego, coraz częściej wskazuje się też na znaczącą rolę zaburzeń immunologicznych.

Wyniki badań doświadczalnych przeprowadzonych na zwierzętach, jak również na hodowlach tkankowych, oraz obserwacje kliniczne potwierdzają udział układu odpornościowego obejmujący aktywność autoreaktywnych limfocytów oraz cytotoksyczne działanie autoprzeciwciał w rozwoju poszczególnych powikłań w obu typach cukrzycy. Wydaje się zatem, że zachwianie równowagi immunologicznej wyzwalające autoagresję jest ważnym czynnikiem przyczyniającym się do dysfunkcji poszczególnych organów w typach cukrzycy 1 i 2.

Dokładne zrozumienie immunopatogenezy tych zaburzeń może zmienić dotychczasowe podejście w leczeniu powikłań cukrzycy oraz umożliwić opracowanie skutecznej terapii przyczynowej ukierunkowanej na układ odpornościowy. Identyfikacja swoistych autoprzeciwciał mogłaby usprawnić ich wczesną diagnostykę i prewencję. W artykule podjęto próbę analizy czynników ryzyka najczęstszych schorzeń o podłożu autoimmunizacyjnym, ich związku z typem 1 i 2 cukrzycy oraz podsumowano potencjalne znaczenie autoagresji w rozwoju jej powikłań w oparciu o wyniki dotychczasowych badań doświadczalnych i klinicznych.

Phospholipid Levels at Seroconversion Are Associated With Resolution of Persistent Islet Autoimmunity: The Diabetes Autoimmunity Study in the Young

Reversion of islet autoimmunity (IA) may point to mechanisms that prevent IA progression. We followed 199 individuals who developed IA during the Diabetes Autoimmunity Study in the Young. Untargeted metabolomics was performed in serum samples following IA. Cox proportional hazards models were used to test whether the metabolites (2,487) predicted IA reversion: two or more consecutive visits negative for all autoantibodies. We conducted a principal components analysis (PCA) of the top metabolites; |hazard ratio (HR) >1.25| and nominal P < 0.01. Phosphatidylcholine (16:0_18:1(9Z)) was the strongest individual metabolite (HR per 1 SD 2.16, false discovery rate (FDR)-adjusted P = 0.0037). Enrichment analysis identified four clusters (FDR P < 0.10) characterized by an overabundance of sphingomyelin (d40:0), phosphatidylcholine (16:0_18:1(9Z)), phosphatidylcholine (30:0), and l-decanoylcarnitine. Overall, 63 metabolites met the criteria for inclusion in the PCA. PC1 (HR 1.4, P < 0.0001), PC2 (HR 0.85, P = 0.0185), and PC4 (HR 1.28, P = 0.0103) were associated with IA reversion. Given the potential influence of diet on the metabolome, we investigated whether nutrients were correlated with PCs. We identified 20 nutrients that were correlated with the PCs (P < 0.05). Total sugar intake was the top nutrient. Overall, we identified an association between phosphatidylcholine, sphingomyelin, and carnitine levels and reversion of IA.

Implication of epigenetic factors in the pathogenesis of type 1 diabetes

Type 1 diabetes (T1D) is an autoimmune disease that resulted from the severe destruction of the insulin-producing β cells in the pancreases of individuals with a genetic predisposition. Genome-wide studies have identified HLA and other risk genes associated with T1D susceptibility in humans. However, evidence obtained from the incomplete concordance of diabetes incidence among monozygotic twins suggests that environmental factors also play critical roles in T1D pathogenesis. Epigenetics is a rapidly growing field that serves as a bridge to link T1D risk genes and environmental exposures, thereby modulating the expression of critical genes relevant to T1D development beyond the changes of DNA sequences. Indeed, there is compelling evidence that epigenetic changes induced by environmental insults are implicated in T1D pathogenesis. Herein, we sought to summarize the recent progress in terms of epigenetic mechanisms in T1D initiation and progression, and discuss their potential as biomarkers and therapeutic targets in the T1D setting.

The roles of vitamin D and cathelicidin in type 1 diabetes susceptibility

Type 1 diabetes has an increasingly greater incidence and prevalence with no cure available. Vitamin D supplementation is well documented to reduce the risk of developing type 1 diabetes. Being involved in the modulation of cathelicidin expression, the question whether cathelicidin may be one of the underlying cause arises. Cathelicidin has been implicated in both the development and the protection against type 1 diabetes by mediating the interplay between the gut microbiome, the immune system and β cell function. While its potential on type 1 diabetes treatment seems high, the understanding of its effects is still limited. This review aims to contribute to a more comprehensive understanding of the potential of vitamin D and cathelicidin as adjuvants in type 1 diabetes therapy.

Multiplexed High-Throughput Serological Assay for Human Enteroviruses

Immunological assays detecting antibodies against enteroviruses typically use a single enterovirus serotype as antigen. This limits the ability of such assays to detect antibodies against different enterovirus types and to detect possible type-specific variation in antibody responses. We set out to develop a multiplexed assay for simultaneous detection of antibodies against multiple enterovirus and rhinovirus types encompassing all human infecting species. Seven recombinant VP1 proteins from enteroviruses EV-A to EV-D and rhinoviruses RV-A to RV-C species were produced. Using Meso Scale Diagnostics U-PLEX platform we were able to study antibody reactions against these proteins as well as non-structural enterovirus proteins in a single well with 140 human serum samples. Adults had on average 33-fold stronger antibody responses to these antigens (p < 10⁻¹¹) compared to children, but children had less cross-reactivity between different enterovirus types. The results suggest that this new high-throughput assay offers clear benefits in the evaluation of humoral enterovirus immunity in children, giving more exact information than assays that are based on a single enterovirus type as antigen.

Type 1 diabetes-early life origins and changing epidemiology

Type 1 diabetes is a chronic, immune-mediated disease characterised by the destruction of insulin-producing cells. Standardised registry data show that type 1 diabetes incidence has increased 3-4% over the past three decades, supporting the role of environmental factors. Although several factors have been associated with type 1 diabetes, none of the associations are of a magnitude that could explain the rapid increase in incidence alone. Moreover, evidence of changing prevalence of these exposures over time is insufficient. Multiple factors could simultaneously explain the changing type 1 diabetes incidence, or the magnitude of observed associations could have been underestimated because of exposure measurement error, or the mismodelling of complex exposure-time-response relationships. The identification of environmental factors influencing the risk of type 1 diabetes and increased understanding of the cause at the individual level, regardless of the ability to explain the changing incidence at the population level, is important because of the implications for prevention.

Antibody Responses against Enterovirus Proteases are Potential Markers for an Acute Infection

BACKGROUND

Enteroviruses are a group of common non-enveloped RNA viruses that cause symptoms ranging from mild respiratory infections to paralysis. Due to the abundance of enterovirus infections it is hard to distinguish between on-going and previous infections using immunological assays unless the IgM fraction is studied.

METHODS

In this study we show using Indirect ELISA and capture IgM ELISA that an IgG antibody response against the nonstructural enteroviral proteins 2A and 3C can be used to distinguish between IgM positive (n = 22) and IgM negative (n = 20) human patients with 83% accuracy and a diagnostic odds ratio of 30. Using a mouse model, we establish that the antibody response to the proteases is short-lived compared to the antibody response to the structural proteins in. As such, the protease antibody response serves as a potential marker for an acute infection.

CONCLUSIONS

Antibody responses against enterovirus proteases are shorter-lived than against structural proteins and can differentiate between IgM positive and negative patients, and therefore they are a potential marker for acute infections.

COVID-19: A Personalized Cardiometabolic Approach for Reducing Complications and Costs. The Role of Aging beyond Topics

COVID 19 is much more than an infectious disease by SARS-CoV-2 followed by a disproportionate immune response. An older age, diabetes and history of cardiovascular disease, especially hypertension, but also chronic heart failure and coronary artery disease among others, are between the most important risk factors. In addition, during the hospitalization both hyperglycaemia and heart failure are frequent. Less frequent are acute coronary syndrome, arrhythmias and stroke. Accordingly, not all prolonged stays or even deaths are due directly to SARS-CoV-2. To our knowledge, this is the first review, focusing both on cardiovascular and metabolic aspects of this dreadful disease, in an integrated and personalized way, following the guidelines of the Cardiometabolic Health/Medicine. Therefore, current personalized aspects such as ACEIs and ARBs, the place of statins and the most appropriate management of heart failure in diabetics are analysed. Aging, better than old age, as a dynamic process, is also considered in this review for the first time in the literature, and not only as a risk factor attributed to cardiovascular and non-cardiovascular comorbidities. Immunosenescence is also approached to build healthier elders, so they can resist present and future infectious diseases, and not only in epidemics or pandemics. In addition, to do this we must start knowing the molecular mechanisms that underlying Aging process in general, and immunosenescence in particular. Surprisingly, the endoplasmic reticulum stress and autophagy are implicated in both process. Finally, with a training in all the aspects covered in this review, not only the hospital stay, complications and costs of this frightening disease in high-risk population should be reduced. Likely, this paper will open a gate to the future for open-minded physicians.

Viruses and Autoimmunity: A Review on the Potential Interaction and Molecular Mechanisms

For a long time, viruses have been shown to modify the clinical picture of several autoimmune diseases, including type 1 diabetes (T1D), systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), Sjögren’s syndrome (SS), herpetic stromal keratitis (HSK), celiac disease (CD), and multiple sclerosis (MS). Best examples of viral infections that have been proposed to modulate the induction and development of autoimmune diseases are the infections with enteric viruses such as Coxsackie B virus (CVB) and rotavirus, as well as influenza A viruses (IAV), and herpesviruses. Other viruses that have been studied in this context include, measles, mumps, and rubella. Epidemiological studies in humans and experimental studies in animal have shown that viral infections can induce or protect from autoimmunopathologies depending on several factors including genetic background, host-elicited immune responses, type of virus strain, viral load, and the onset time of infection. Still, data delineating the clear mechanistic interaction between the virus and the immune system to induce autoreactivity are scarce. Available data indicate that viral-induced autoimmunity can be activated through multiple mechanisms including molecular mimicry, epitope spreading, bystander activation, and immortalization of infected B cells. Contrarily, the protective effects can be achieved via regulatory immune responses which lead to the suppression of autoimmune phenomena. Therefore, a better understanding of the immune-related molecular processes in virus-induced autoimmunity is warranted. Here we provide an overview of the current understanding of viral-induced autoimmunity and the mechanisms that are associated with this phenomenon.

Hand, foot, and mouth disease in pregnancy: 7 years Tuscan experience and literature review

OBJECTIVE

Evaluation of hand, foot, and mouth disease (HFMD) diagnostic strategies in pregnancy and the risk of HFMD-related fetopathy.

STUDY DESIGN

Pregnant women consecutively evaluated between 2010 and 2016 at the Tuscany Reference Center for Infectious Diseases in Pregnancy for HFMD were enrolled. A descriptive analysis of infected patients/newborns data and literature review were carried out.

RESULT

Of the 128 women evaluated, 52 (41%) were symptomatic: 32 (61.5%) developed HFM vesicles, 12 (23%) palmoplantar vesicles, and 8 (15.5%) oral aphthae. Serological positivity and direct Enterovirus detection on blood and vesicle were obtained in 1.9% (1/52), 9.1% (1/11), and 68.7% (11/16), respectively. Three miscarriage and few cases of fetal/neonatal anomalies were reported.

CONCLUSION

HFMD diagnosis is primarily a clinical diagnosis. Direct viral detection is more sensitive than serology. Considering our series and literature review, data on embryo-fetal-neonatal outcomes are not conclusive. Although the role of EV as causative agents of congenital defects remains uncertain, the described cases of unfavorable outcome impose prudence and monitoring of pregnant women with HFMD throughout the gestation.

The Prevalence of Celiac Disease-Specific Auto-Antibodies in Type 1 Diabetes in a Moroccan Population

OBJECTIVE

We aimed to determine the prevalence of specific auto-antibodies to celiac disease (CD) in Moroccan type 1 diabetic (T1D) patients and compare the clinical and biological characteristics of seropositive and seronegative cases.

PATIENTS AND METHODS

A cross-sectional study was carried out on 276 T1D patients including 109 adults and 167 pediatric cases. The screening for CD was performed by an Elisa IgA anti-tissue transglutaminase antibody (tTGA) testing, combined with IgA quantification by nephelometry. Positive-IgA-tTGA cases were secondly tested for anti-endomysial antibodies (EMA) using an immunofluorescence technique, and the IgA deficiency cases were screened for IgG-tTGA. Patients with low positive tTGA titers underwent HLA-DQ2/DQ8 typing. Sociodemographic and clinical data of the patients were collected using a hetero-administered questionnaire. The comparison of clinical and biological data between seropositive and seronegative diabetics was done using independent T, Mann-Whitney U, chi-squared, and Fisher tests, which were considered significant if p value <0.05.

RESULTS

The prevalence of CD-specific auto-antibodies was estimated to be 9.1% (IC = 95%), with 25 positive cases in tTGA and EMA testing. Eight cases displayed low titers of IgA-tTGA, among which 4 were positive for HLA-DQ2, 1 for HLA-DQ8, and 1 for both DQ2 and DQ8. The other 2 cases had a biopsy-proven CD. Compared to seronegative patients, seropositive cases had a higher percentage of associated autoimmune disorders (16% vs. 2.4%, p=0.008), with a significant lower height Z-scores (median: -0.90 (-3.93 to 0.95) vs. -0.51 (-4.54 to 2.18), p=0.029) and a higher HbA1c level (median: 11.30% (7.31 to 16.00) vs. 9.30% (4.40 to17.31), p=0.022).

CONCLUSION

The current study gave evidence of a high prevalence of CD specific auto-antibodies in T1D population. The co-existence of these two conditions was associated with a poor glycemic control, a lower height, and other autoimmune diseases. These findings may suggest the necessity of a systematic screening of CD in T1D patients.

Immunomodulatory Effect of Vitamin D and Its Potential Role in the Prevention and Treatment of Type 1 Diabetes Mellitus-A Narrative Review

Type 1 diabetes mellitus is a chronic autoimmune disease associated with degeneration of pancreatic β-cells that results in an inability to produce insulin and the need for exogenous insulin administration. It is a significant global health problem as the incidence of this disorder is increasing worldwide. The causes are still poorly understood, although it certainly has genetic and environmental origins. Vitamin D formed profusely in the skin upon exposure to sunlight, as well as from dietary sources, exhibits an immunomodulatory effect based on gene transcription control. Indeed, vitamin D can downregulate mechanisms connected with adaptive immunity, induce immunological tolerance and decrease auto-aggression-related inflammation. These properties provide the basis for a preventive and therapeutic role of vitamin D. As many studies have demonstrated, appropriate supplementation with vitamin D reduces the risk of autoimmune diseases, including type 1 diabetes mellitus, and alleviates disease symptoms in patients. The aim of this narrative review is to present the molecular mechanisms for the vitamin D immunomodulatory effect as well as review human clinical studies on the use of vitamin D as adjuvant therapy in type 1 diabetes mellitus.

The Coincidence of Newly Diagnosed Type 1 Diabetes Mellitus with IgM Antibody Positivity to Enteroviruses and Respiratory Tract Viruses

OBJECTIVE

Viruses trigger and promote islet cell destruction and cause type 1 diabetes mellitus (T1DM). However, the existence of a cause-and-effect relationship is under debate. The aim of this study is to investigate the sero-epidemiological and molecular evidence on enteroviruses and respiratory viruses in patients with newly diagnosed T1DM during the cold season.

DESIGN

Forty children newly diagnosed with T1DM and 30 healthy children who presented to the clinic over the course of a year were included in the study. The IgM antibodies against enteroviruses and respiratory viruses were studied using the indirect immunofluorescence assay (IFA) test, and no CBV4-specific RNA was detected in the children. The onset times of T1DM were classified into fall-winter and spring-summer seasons and separated into cold, moderate, or warm months in terms of temperature.

RESULTS

The percentages of viral IgM antibodies against most common viruses were detected in the patients as follows: influenza B (IVB) (70%), echovirus 7 (ECHO7) (45%), parainfluenza virus 4 (PIV4) (40%), coxsackievirus A7 (CAV7) (27.5%), and H3N2 (22.5%). Compared with the control group, the above viruses had a significant association with T1DM (p ≤ 0.001, p ≤ 0.001, p = 0.035, p = 0.003, and p = 0.023, resp.). CBV4-specific RNA was not detected in any serum. A total of 75% and 95% patients were diagnosed with T1DM in the fall-winter seasons and cold-moderate months, respectively.

CONCLUSION

Our study demonstrates the significant association between T1DM and the presence of IgM antibodies against IVB, ECHO7, PIV4, CAV7, and H3N2, and the majority of newly diagnosed T1DM appeared in the fall-winter season. It suggests that enteroviruses and respiratory viruses, in addition to seasonal variation, could play a role in the etiopathogenesis and clinical onset of T1DM.

The Role of Epigenetics in Type 1 Diabetes

PURPOSE OF REVIEW

Epigenetics is defined as mitotically heritable changes in gene expression that do not directly alter the DNA sequence. By implication, such epigenetic changes are non-genetically determined, although they can be affected by inherited genetic variation. Extensive evidence indicates that autoimmune diseases including type 1 diabetes are determined by the interaction of genetic and non-genetic factors. Much is known of the genetic causes of these diseases, but the non-genetic effects are less clear-cut. Further, it remains unclear how they interact to cause the destructive autoimmune process. This review identifies the key issues in the genetic/non-genetic interaction, examining the most recent evidence of the role of non-genetic effects in the disease process, including the impact of epigenetic effects on key pathways.

RECENT FINDINGS

Recent research indicates that these pathways likely involve immune effector cells both of the innate and adaptive immune response. Specifically, there is evidence of cell type-specific enrichment in altered DNA methylation, changes which were temporally stable and enriched at gene regulatory elements. Epigenomics remains in its infancy, and we anticipate further studies will define how the interaction of genetic and non-genetic effects induces tissue-specific destruction and enhances our ability to predict, and possibly even modify that process.

Review of the clinical significance of respiratory virus infections in newborn infants

Respiratory viruses have been recognised as causative agents for a wide spectrum of clinical manifestations and severe respiratory compromise in neonates during birth hospitalisation. Early‐life respiratory virus infections have also been shown to be associated with adverse long‐term consequences.

Conclusion

Preventing virus infections by intensifying hygiene measures and cohorting infected infants should be a major goal for neonatal intensive care units, as well as more common use of virus diagnostics. Active virus surveillance and long‐term follow‐up are needed to ascertain the causality and exact underlying mechanisms for adverse long‐term consequences.

Broad-Spectrum Antibiotic Treatment and Subsequent Childhood Type 1 Diabetes: A Nationwide Danish Cohort Study

Background

Studies link antibiotic treatment and delivery by cesarean section with increased risk of chronic diseases through changes of the gut-microbiota. We aimed to evaluate the association of broad-spectrum antibiotic treatment during the first two years of life with subsequent onset of childhood type 1 diabetes and the potential effect-modification by mode of delivery.

Materials and Methods

A Danish nationwide cohort study including all singletons born during 1997–2010. End of follow-up by December 2012. Four national registers provided information on antibiotic redemptions, outcome and confounders. Redemptions of antibiotic prescriptions during the first two years of life was classified into narrow-spectrum or broad-spectrum antibiotics. Children were followed from age two to fourteen, both inclusive. The risk of type 1 diabetes with onset before the age of 15 years was assessed by Cox regression. A total of 858,201 singletons contributed 5,906,069 person-years, during which 1,503 children developed type 1 diabetes.

Results

Redemption of broad-spectrum antibiotics during the first two years of life was associated with an increased rate of type 1 diabetes during the following 13 years of life (HR 1.13; 95% CI 1.02 to 1.25), however, the rate was modified by mode of delivery. Broad-spectrum antibiotics were associated with an increased rate of type 1 diabetes in children delivered by either intrapartum cesarean section (HR 1.70; 95% CI 1.15 to 2.51) or prelabor cesarean section (HR 1.63; 95% CI 1.11 to 2.39), but not in vaginally delivered children. Number needed to harm was 433 and 562, respectively. The association with broad-spectrum antibiotics was not modified by parity, genetic predisposition or maternal redemption of antibiotics during pregnancy or lactation.

Conclusions

Redemption of broad-spectrum antibiotics during infancy is associated with an increased risk of childhood type 1 diabetes in children delivered by cesarean section.

Stem cell therapy emerging as the key player in treating type 1 diabetes mellitus

Type 1 diabetes mellitus (T1DM) is an autoimmune disease causing progressive destruction of pancreatic β cells, ultimately resulting in loss of insulin secretion producing hyperglycemia usually affecting children. Replacement of damaged β cells by cell therapy can treat it. Currently available strategies are insulin replacement and islet/pancreas transplantation. Unfortunately these offer rescue for variable duration due to development of autoantibodies. For pancreas/islet transplantation a deceased donor is required and various shortfalls of treatment include quantum, cumbersome technique, immune rejection and limited availability of donors. Stem cell therapy with assistance of cellular reprogramming and β-cell regeneration can open up new therapeutic modalities. The present review describes the history and current knowledge of T1DM, evolution of cell therapies and different cellular therapies to cure this condition.

Environmental risk factors for type 1 diabetes

The incidence of type 1 diabetes has risen considerably in the past 30 years due to changes in the environment that have been only partially identified. In this Series paper, we critically discuss candidate triggers of islet autoimmunity and factors thought to promote progression from autoimmunity to overt type 1 diabetes. We revisit previously proposed hypotheses to explain the growth in the incidence of type 1 diabetes in light of current data. Finally, we suggest a unified model in which immune tolerance to β cells can be broken by several environmental exposures that induce generation of hybrid peptides acting as neoautoantigens.

Exposure to sunshine early in life prevented development of type 1 diabetes in Danish boys

BACKGROUND

We aimed to assess the association between exposure to sunshine during gestation and the risk of type 1 diabetes (T1D) in Danish children.

METHODS

The study population included 331,623 individuals born in Denmark from 1983 to 1988; 886 (0.26%) developed T1D by the age of 15 years. The values of sunshine hours were obtained from the Danish Meteorological Institute. Gestational exposure to sunshine was calculated by summing recorded monthly sunshine hours during the full 9 months prior to the month of birth. The linear variable then was split into two categories separated by the median value.

RESULTS AND CONCLUSIONS

Cox regression models showed that more sunshine during the third gestational trimester was associated with lower hazards (HR) of T1D at age 5-9 years in males: HR (95% CI): 0.60 (0.43-0.84), p=0.003. Our results should be considered in the context of evidence-based recommendations to the public about skin protection from the sun.

Seasonal variation in month of diagnosis in children with type 1 diabetes registered in 23 European centers during 1989-2008: little short-term influence of sunshine hours or average temperature

BACKGROUND

The month of diagnosis in childhood type 1 diabetes shows seasonal variation.

OBJECTIVE

We describe the pattern and investigate if year-to-year irregularities are associated with meteorological factors using data from 50 000 children diagnosed under the age of 15 yr in 23 population-based European registries during 1989-2008.

METHODS

Tests for seasonal variation in monthly counts aggregated over the 20 yr period were performed. Time series regression was used to investigate if sunshine hour and average temperature data were predictive of the 240 monthly diagnosis counts after taking account of seasonality and long term trends.

RESULTS

Significant sinusoidal pattern was evident in all but two small centers with peaks in November to February and relative amplitudes ranging from ± 11 to ± 38% (median ± 17%). However, most centers showed significant departures from a sinusoidal pattern. Pooling results over centers, there was significant seasonal variation in each age-group at diagnosis, with least seasonal variation in those under 5 yr. Boys showed greater seasonal variation than girls, particularly those aged 10-14 yr. There were no differences in seasonal pattern between four 5-yr sub-periods. Departures from the sinusoidal trend in monthly diagnoses in the period were significantly associated with deviations from the norm in average temperature (0.8% reduction in diagnoses per 1 °C excess) but not with sunshine hours.

CONCLUSIONS

Seasonality was consistently apparent throughout the period in all age-groups and both sexes, but girls and the under 5 s showed less marked variation. Neither sunshine hour nor average temperature data contributed in any substantial way to explaining departures from the sinusoidal pattern.

Vitamin D fortification and seasonality of birth in type 1 diabetic cases: D-tect study

Fortification of margarine with vitamin D was mandatory in Denmark during 1961-1985. The aim of the study was to assess whether gestational and early infancy exposure to margarine fortification was associated with seasonality of birth in Danish type 1 diabetes (T1D) patients. The risks of T1D in Danes born during various exposure periods around margarine fortification termination in 1985 were analyzed. As expected, the T1D hazards in males unexposed to margarine fortification and born in spring were higher than in males born in autumn: relevant hazard ratios (95% confidence intervals) in various exposure groups ranged from 1.74 (1.112/2.708) to 37.43 (1.804/776.558). There were no indications of seasonality of birth in males exposed to fortification, nor in both exposed and unexposed females. The study suggests that early life exposure to low-dose vitamin D from fortified food eliminates seasonality of birth in T1D male patients. Further studies are required to investigate the identified gender differences.

Antibodies to VP1 of swine pasivirus in humans without evidence of transmission from a pig source

BACKGROUND

Swine pasivirus (SPaV1) is a recently described enteric virus close to human parechoviruses and highly prevalent in pigs. Antibodies to Escherichia coli-expressed VP1 of SpaV1 have been found in a majority of humans in China.

OBJECTIVES

The objectives were to estimate the antibody prevalence in a European country, to test if exposure to the virus was linked to pig products and if this exposure was a risk factor for the development of diabetes type 1.

STUDY DESIGN

An ELISA test was developed and used to screen 842 healthy subjects with known exposure to pig products, 39 patients with diabetes type 1 and 20 controls.

RESULTS

We identified a high seroprevalence (15.6%) reacting to VP1 of SPaV1 among healthy human subjects. Analysis of risk factors argues against cross-species transmission from pigs as the source of infection. Data also indicate that the presence of SPaV1 VP1-binding antibodies is not associated with diabetes type 1 in humans.

CONCLUSION

Our results suggest that the seroreactivity frequently found in humans against SpaV1 is due to cross-reactivity with related antigen, perhaps a picornavirus, and that SpaV1 is not a zoonotic virus.

The prevalence of type 1 diabetes mellitus among 15-34-year-aged Lithuanian inhabitants during 1991-2010

AIMS

To summarize the data on the prevalence of type 1 diabetes mellitus among 15-34-year-aged Lithuania inhabitants (1991-2010).

METHODS

New prevalent cases consist of growing-up patients with diabetes onset in childhood, i.e., up to 14 years, new onset 15-34-year-aged type 1 diabetic patients Lithuanian inhabitants, and immigrants. The data on type 1 diabetes was collected with the help of general practitioners and regional endocrinologists in Lithuania.

RESULTS

On 31 December 1991, there were 1202 adolescent and adult 15-34-year-aged patients with type 1 diabetes mellitus or 103.59 per 100,000 inhabitants of the same age group (95% Poisson CI 97.90-109.62), and at the end of 2010 - 1533 or 187.80 (178.63-197.44), respectively in Lithuania. During 19-year period the mean increase of type 1 diabetic patients was 1.25±1.94% per year or 1.47±2.74 per 100,000 inhabitants per mean year of the study period (for males 1.42±2.14% or 1.69±3.05/100,000 and for females 1.05±1.99%, or 1.24±2.92/100,000). Regression-based linear trends showed that the prevalence of type 1 diabetes mellitus in 15-34-year-age group had a tendency to increase among males (r=0.953; p<0.001) and females (r=0.970; p<0.001). The age adjusted prevalence frequencies for males and females in 1991 were correspondingly 102.81/100,000 and 104.55/100,000, and in 2010 - 193.75 and 182.01.

CONCLUSION

The prevalence of type 1 diabetes mellitus among 15-34-year-age males and females had a tendency to increase during 1991-2010.

Interferon and interferon-inducible gene activation in patients with type 1 diabetes

Type 1 diabetes (T1D) is an autoimmune disease that is thought to be triggered by environmental factors in genetically susceptible individuals. Enteroviruses have been mentioned as the most probable induction component of the disease. Nevertheless, the literature is controversial regarding the association of T1D with viral infection and first-line antiviral defence components, for example type I interferons (IFNs). Our aim was to test the hypothesis that an abnormality in IFN-stimulated gene patterns may cause a failure in immunological tolerance and, thereby, initiate T1D as an autoimmune disorder. We studied material from 64 T1D and 36 control subjects, divided into two age groups: <10 years and ≥10 years old. Using a relative gene expression method, we observed a lower expression of interferon-induced helicase 1 (IFIH1) and other type I IFN-induced genes in the blood cells of T1D subjects, especially subjects under 10 years old, in spite of their higher IFN levels as measured by the pSTAT1-inducing capacity of their sera. Likewise, freshly purified CpG-stimulated cells from T1D patients showed significantly lower upregulation of IFN-induced genes, that is IFIH1 and CXCL10, compared to cells from the control group. The identified dysregulation in the IFN-α-induced antiviral response in T1D patients, especially in early childhood, could be one of the factors affecting T1D development.

Enterovirus RNA in longitudinal blood samples and risk of islet autoimmunity in children with a high genetic risk of type 1 diabetes: the MIDIA study

AIMS/HYPOTHESIS

Only a few longitudinal molecular studies of enterovirus and islet autoimmunity have been reported, and positive results seem to be limited to Finland. We aimed to investigate an association between enterovirus RNA in blood and islet autoimmunity in the MIDIA study from Norway, a country which largely shares environmental and economic features with Finland.

METHODS

We analysed serial blood samples collected at ages 3, 6, and 9 months and then annually from 45 children who developed confirmed positivity for at least two autoantibodies (against insulin, GAD65 and IA-2) and 92 matched controls, all from a cohort of children with a single high-risk HLA-DQ-DR genotype. Enterovirus was tested in RNA extracted from frozen blood cell pellets, using real-time RT-PCR with stringent performance control.

RESULTS

Out of 807 blood samples, 72 (8.9%) were positive for enterovirus. There was no association between enterovirus RNA and islet autoimmunity in samples obtained strictly before (7.6% cases, 10.0% controls, OR 0.75 [95% CI 0.36, 1.57]), or strictly after the first detection of islet autoantibodies (10.5% case, 5.8% controls, OR 2.00 [95% CI 0.64, 6.27]). However, there was a tendency towards a higher frequency of enterovirus detection in the first islet autoantibody-positive sample (15.8%) compared with the corresponding time point in matched controls (3.2%, OR 8.7 [95% CI 0.97, 77]). Neither of these results was changed by adjusting for potential confounders, restricting to various time intervals or employing various definitions of enterovirus positivity.

CONCLUSIONS/INTERPRETATION

Positivity for enterovirus RNA in blood did not predict the later induction of islet autoantibodies, but enterovirus tended to be detected more often at the islet autoantibody seroconversion stage.

Long term effect of gut microbiota transfer on diabetes development

The composition of the gut microbiome represents a very important environmental factor that influences the development of type 1 diabetes (T1D). We have previously shown that MyD88-deficient non-obese diabetic (MyD88-/-NOD) mice, that were protected from T1D development, had a different composition of gut microbiota compared to wild type NOD mice. The aim of our study was to investigate whether this protection could be transferred. We demonstrate that transfer of gut microbiota from diabetes-protected MyD88-deficient NOD mice, reduced insulitis and significantly delayed the onset of diabetes. Gut bacteria from MyD88-deficient mice, administered over a 3-week period, starting at 4 weeks of age, stably altered the family composition of the gut microbiome, with principally Lachnospiraceae and Clostridiaceae increased and Lactobacillaceae decreased. The transferred mice had a higher concentration of IgA and TGFβ in the lumen that was accompanied by an increase in CD8(+)CD103(+) and CD8αβ T cells in the lamina propria of the large intestine. These data indicate not only that gut bacterial composition can be altered after the neonatal/weaning period, but that the composition of the microbiome affects the mucosal immune system and can delay the development of autoimmune diabetes. This result has important implications for the development of probiotic treatment for T1D.

Type 1 diabetes

Over the past decade, knowledge of the pathogenesis and natural history of type 1 diabetes has grown substantially, particularly with regard to disease prediction and heterogeneity, pancreatic pathology, and epidemiology. Technological improvements in insulin pumps and continuous glucose monitors help patients with type 1 diabetes manage the challenge of lifelong insulin administration. Agents that show promise for averting debilitating disease-associated complications have also been identified. However, despite broad organisational, intellectual, and fiscal investments, no means for preventing or curing type 1 diabetes exists, and, globally, the quality of diabetes management remains uneven. This Seminar discusses current progress in epidemiology, pathology, diagnosis, and treatment of type 1 diabetes, and prospects for an improved future for individuals with this disease.

From immunobiology to β-cell biology: the changing perspective on type 1 diabetes

Type 1 Diabetes (T1D) is characterized by the immune mediated destruction of β cells. Clinical studies have focused on drug therapies to modulate autoimmunity, yet none of these interventions has resulted in durable preservation of β-cell function. These findings raise the possibility that initiating or propagating events outside of the immune system should be considered in future efforts to prevent or reverse T1D. An emerging concept suggests that defects inherent to the β cell may trigger autoimmunity. A study by Engin et al. in type 1 diabetic NOD mice suggests that excessive β-cell endoplasmic reticulum stress arising from environmental insults results in abnormal protein synthesis, folding, and/or processing. Administration of the chemical protein folding chaperone TUDCA resulted in recovery of β-cell endoplasmic reticulum function and a diminished incidence of diabetes in NOD mice. We propose here that these data and others support a model whereby an inadequate or defective β-cell endoplasmic reticulum response results in the release of β-cell antigens and neoantigens that initiate autoimmunity. Pharmacologic therapies that either mitigate these early β-cell stressors or enhance the ability of β cells to cope with such stressors may prove to be effective in the prevention or treatment of T1D.

The genetics of innate immunity sensors and human disease

Since their discovery, innate immunity microbial sensors have been increasingly studied and shown to play a critical role in innate responses to microbes in several experimental in vitro, ex vivo, and animal models. However, their role in the human response to infection in natural conditions has just started to be deciphered, by means of clinical studies of primary immunodeficiencies and epidemiological genetic studies. Here, we summarize the major findings concerning the genetic diversity of the various families of microbial sensors in humans, and of other molecules involved in the signaling pathways they trigger. Specifically, we review the genetic associations, revealed by both clinical and epidemiological genetics studies, of microbial sensors from five different families: Toll-like receptors, C-type lectin receptors, NOD-like receptors, RIG-I-like receptors, and cytosolic DNA sensors. In particular, we consider the relationships between variation at the genes encoding these molecules and susceptibility to and the severity of infectious diseases and other clinical conditions associated with immune dysfunction, including autoimmunity, inflammation, allergy, and cancer. Despite the fact that the genetic links between innate immunity sensors and human disorders remain still limited, human genetics studies are increasingly improving our understanding of the genuine functions of microbial sensors and downstream signaling molecules in the natural setting.

Enteroviral pathogenesis of type 1 diabetes: queries and answers

PURPOSE OF REVIEW

Type 1 diabetes (T1D) results from interplay between genetic predisposition, immune system, and environmental factors. Epidemiological and experimental data strongly suggest a role for enteroviruses in the development of T1D, but a lot of controversies and unanswered questions remained. This review focuses on issues that are fueling debate.

RECENT FINDINGS

Beyond HLA genes, which provide genetic susceptibility for T1D, other loci have been identified to be associated with the disease. There is a link between T1D and single-nucleotide polymorphisms (SNPs) in the interferon-induced helicase 1 (IFIH1) gene that encodes melanoma differentiation-associated protein 5 (MDA5). This protein is a cytoplasmic sensor for viruses especially coxsackieviruses B, the most incriminated enteroviruses in T1D pathogenesis. Upon viral infection, MDA5 stimulates the production of mediators of the innate antiviral immune response, which is believed to play a role in a 'bystander activation' scenario. Rare variants of IFIH1 through a lost or reduced expression of the protein are protective against T1D, whereas common IFIH1 SNPs are associated with the disease. However, a clear association has not been yet established between T1D-associated IFIH1 polymorphisms and enterovirus detection.

SUMMARY

Literature have accumulated a lot of evidence supporting that enteroviruses can contribute, at least in some patients, to the pathogenesis of T1D through various mechanisms. But it is still a challenge to date to prove a causal relationship between enteroviruses and T1D. Future studies may lead to a better understanding of this relationship and ultimately can help toward disease prevention.

The prenatal environment and type 1 diabetes

There is ample evidence that environmental factors are involved in the aetiology of type 1 diabetes, but the nature and timing of the interactions are poorly understood. The intrauterine environment is known to play a role in the later development of type 2 diabetes, and this review considers a possible role in type 1 diabetes. Autoimmune type 1 diabetes is rare in those diagnosed before 6 months of age, but endogenous autoantibodies predictive of future type 1 diabetes may be detectable by 6-12 months of age, suggesting that environmental factors may operate before this age in some cases. Indirect evidence of a protective effect for the intrauterine environment comes from the observation that mothers with type 1 diabetes are less likely than affected fathers to transmit diabetes to their offspring, although the precise role (if any) is unclear. The risk of childhood-onset type 1 diabetes increases with maternal age at delivery, and with high birthweight, but these associations are weak and heterogeneous, and these factors are unlikely to be directly causally related to type 1 diabetes. No firm conclusion can be drawn from studies of maternal enteroviral infection or from various nutritional exposures. The birth process itself may play a role, as suggested by the slightly increased risk in children born by Caesarean section; lack of contact with maternal bacteria is one suggested mechanism. In sum, there is circumstantial evidence, but no proof of principle, that maternal or intrauterine conditions may modulate genetic risk of type 1 diabetes. The disease process culminating in type 1 diabetes typically begins in early life, but it is not clear whether the trail begins before or after birth.

Next-generation sequencing for viruses in children with rapid-onset type 1 diabetes

AIMS/HYPOTHESIS

Viruses are candidate causative agents in the pathogenesis of autoimmune (type 1) diabetes. We hypothesised that children with a rapid onset of type 1 diabetes may have been exposed to such agents shortly before the initiation of islet autoimmunity, possibly at high dose, and thus study of these children could help identify viruses involved in the development of autoimmune diabetes.

METHODS

We used next-generation sequencing to search for viruses in plasma samples and examined the history of infection and fever in children enrolled in The Environmental Determinants of Diabetes in the Young (TEDDY) study who progressed to type 1 diabetes within 6 months from the appearance of islet autoimmunity, and in matched islet-autoantibody-negative controls.

RESULTS

Viruses were not detected more frequently in plasma from rapid-onset patients than in controls during the period surrounding seroconversion. In addition, infection histories were found to be similar between children with rapid-onset diabetes and control children, although episodes of fever were reported less frequently in children with rapid-onset diabetes.

CONCLUSIONS/INTERPRETATION

These findings do not support the presence of viraemia around the time of seroconversion in young children with rapid-onset type 1 diabetes.

Progress in immune-based therapies for type 1 diabetes

Immune-based therapies that prevent type 1 diabetes or preserve metabolic function remaining at diagnosis have become a major objective for funding agencies and international trial consortia, and receive backing from notable patient advocate groups. The development of immune-based therapeutic strategies in this arena requires a careful balancing of the risks of the therapy against the potential benefits, because many individuals are diagnosed or identified as being at increased risk of disease in early childhood, a period when manipulation of the developing immune system should be undertaken with caution. In addition, a therapy exists (daily insulin injection) that is life-saving in the acute stages of disease and can be used effectively over a lifetime as maintenance. Conversely, the disease is increasing in incidence; is peaking in ever-younger age groups; carries significant risk of increased morbidity and early mortality; and remains difficult to manage effectively in many settings. With these issues in mind, in this article we review progress towards immune-based strategies for this chronic autoimmune disease.

Immunological biomarkers: catalysts for translational advances in autoimmune diabetes

In a recent workshop organized by the JDRF focused on the 'Identification and Utilization of Robust Biomarkers in Type1 Diabetes', leaders in the field of type 1 diabetes (T1D)/autoimmunity and assay technology came together from academia, government and industry to assess the current state of the field, evaluate available resources/technologies and identify gaps that need to be filled for moving the field of T1D research forward. The highlights of this workshop are discussed in this paper, as well as the proposal for a larger, planned consortium effort, incorporating a JDRF Biomarker Core, to foster collaboration and accelerate progress in this critically needed area of T1D research.

Phenylmethimazole suppresses dsRNA-induced cytotoxicity and inflammatory cytokines in murine pancreatic beta cells and blocks viral acceleration of type 1 diabetes in NOD mice

Accumulating evidence supports a role for viruses in the pathogenesis of type 1 diabetes mellitus (T1DM). Activation of dsRNA-sensing pathways by viral dsRNA induces the production of inflammatory cytokines and chemokines that trigger beta cell apoptosis, insulitis, and autoimmune-mediated beta cell destruction. This study was designed to evaluate and describe potential protective effects of phenylmethimazole (C10), a small molecule which blocks dsRNA-mediated signaling, on preventing dsRNA activation of beta cell apoptosis and the inflammatory pathways important in the pathogenesis of T1DM. We first investigated the biological effects of C10, on dsRNA-treated pancreatic beta cells in culture. Cell viability assays, quantitative real-time PCR, and ELISAs were utilized to evaluate the effects of C10 on dsRNA-induced beta cell cytotoxicity and cytokine/chemokine production in murine pancreatic beta cells in culture. We found that C10 significantly impairs dsRNA-induced beta cell cytotoxicity and up-regulation of cytokines and chemokines involved in the pathogenesis of T1DM, which prompted us to evaluate C10 effects on viral acceleration of T1DM in NOD mice. C10 significantly inhibited viral acceleration of T1DM in NOD mice. These findings demonstrate that C10 (1) possesses novel beta cell protective activity which may have potential clinical relevance in T1DM and (2) may be a useful tool in achieving a better understanding of the role that dsRNA-mediated responses play in the pathogenesis of T1DM.

In type 1 diabetes a subset of anti-coxsackievirus B4 antibodies recognize autoantigens and induce apoptosis of pancreatic beta cells

Type 1 diabetes is characterized by autoimmune destruction of pancreatic beta cells. The role played by autoantibodies directed against beta cells antigens in the pathogenesis of the disease is still unclear. Coxsackievirus B infection has been linked to the onset of type 1 diabetes; however its precise role has not been elucidated yet. To clarify these issues, we screened a random peptide library with sera obtained from 58 patients with recent onset type 1 diabetes, before insulin therapy. We identified an immunodominant peptide recognized by the majority of individual patients’sera, that shares homology with Coxsackievirus B4 VP1 protein and with beta-cell specific autoantigens such as phogrin, phosphofructokinase and voltage-gated L-type calcium channels known to regulate beta cell apoptosis. Antibodies against the peptide affinity-purified from patients’ sera, recognized the viral protein and autoantigens; moreover, such antibodies induced apoptosis of the beta cells upon binding the L-type calcium channels expressed on the beta cell surface, suggesting a calcium dependent mechanism. Our results provide evidence that in autoimmune diabetes a subset of anti-Coxsackievirus antibodies are able to induce apoptosis of pancreatic beta cells which is considered the most critical and final step in the development of autoimmune diabetes without which clinical manifestations do not occur.

Immunological pathways to β-cell damage in Type 1 diabetes

Following almost 30 years of intensive research, initiated by the observation that Type 1 diabetes development is associated with a characteristic pancreatic immune cell infiltrate, a picture is emerging of which of the diverse effector arms of the immune system are involved in β-cell destruction. Like any chronic pathology, there is considerable complexity, and our ability to model the disease is hampered by a lack of ready access to the target organ and limited longitudinal analyses. However, it seems that putative pathways can start to be ruled in and out, in part as a result of focused mechanistic studies that make use of new technologies, and in part through analysis of the outcomes of clinical trials of new agents aimed at halting the disease process. The picture that emerges suggests a pathway to prevention that may require combinations of therapeutic agents that target different aspects of the immune system and will need to be used with due attention to their risk-benefit profiles.

The multiple origins of Type 1 diabetes

It is widely accepted that Type 1 diabetes is a complex disease. Genetic predisposition and environmental factors favour the triggering of autoimmune responses against pancreatic β-cells, eventually leading to β-cell destruction. Over 40 susceptibility loci have been identified, many now mapped to known genes, largely supporting a dominant role for an immune-mediated pathogenesis. This role is also supported by the identification of several islet autoantigens and antigen-specific responses in patients with recent onset diabetes and subjects with pre-diabetes. Increasing evidence suggests certain viruses as a common environmental factor, together with diet and the gut microbiome. Inflammation and insulin resistance are emerging as additional cofactors, which might be interrelated with environmental factors. The heterogeneity of disease progression and clinical manifestations is likely a reflection of this multifactorial pathogenesis. So far, clinical trials have been mostly ineffective in delaying progression to overt diabetes in relatives at increased risk, or in reducing further loss of insulin secretion in patients with new-onset diabetes. This limited success may reflect, in part, our incomplete understanding of key pathogenic mechanisms, the lack of truly robust biomarkers of both disease activity and β-cell destruction, and the inability to assess the relative contributions of various pathogenic mechanisms at various time points during the course of the natural history of Type 1 diabetes. Emerging data and a re-evaluation of histopathological, immunological and metabolic findings suggest the hypothesis that unknown mechanisms of β-cell dysfunction may be present at diagnosis, and may contribute to the development of hyperglycaemia and clinical symptoms.

Enterovirus RNA in peripheral blood may be associated with the variants of rs1990760, a common type 1 diabetes associated polymorphism in IFIH1

Objective

Polymorphisms in the IFIH1 (common rs1990760 and four rare rs35667974, rs35337543, rs35744605, rs35732034) have been convincingly associated with type 1 diabetes. The encoded protein (interferon-induced helicase C domain-containing protein 1) senses double-stranded RNA during replication of Picornavirales, including Enterovirus, a genus suspected in the etiology of type 1 diabetes. We therefore investigated whether the polymorphisms are associated with differences in the frequency of enterovirus RNA in blood.

Research Design and Methods

The study included 1001 blood samples, each from a child participating in the Norwegian ‘Environmental Triggers of Type 1 Diabetes: the MIDIA study’. The enterovirus RNA was tested using qualitative semi-nested real-time reverse transcriptase PCR on RNA extracted from frozen cell packs after removal of plasma. Stool samples previously analyzed for enterovirus RNA were available in 417 children.

Results

The genotypes of IFIH1 rs1990760 were associated with different frequencies of enterovirus RNA in blood (7.0%, 14.4% and 9.5% bloods were enterovirus positive among children carrying the Ala/Ala, Ala/Thr and Thr/Thr genotypes, respectively, p = 0.012). This association remained essentially unchanged after adjustment for age and calendar year. The presence of enterovirus in the concomitantly sampled stool further increased the likelihood of enterovirus RNA in blood (odds ratio 2.40, CI 95% 1.13–4.70), but did not affect the association with IFIH1 rs1990760. The rare polymorphisms (individually, or pooled) were not significantly associated with enterovirus RNA in blood.

Conclusions

The common IFIH1 SNP may modify the frequency of enterovirus RNA in blood of healthy children. This effect can help explain the association of IFIH1 with type 1 diabetes.