Viral infections as potential triggers of type 1 diabetes

Association of metabolic syndrome with development of new-onset diabetes after transplantation

BACKGROUND

New-onset diabetes after transplantation (NODAT) is a major posttransplant complication associated with lower allograft and recipient survival. Our objective was to determine whether metabolic syndrome pretransplant is independently associated with NODAT development.

METHODS

We recruited 640 consecutive incident nondiabetic renal transplant recipients from three academic centers between 1999 and 2004. NODAT was defined as the use of hypoglycemic medication, a random plasma glucose level more than 200 mg/dL, or two fasting glucose levels more than or equal to 126 mg/dL beyond 30 days posttransplant.

RESULTS

Metabolic syndrome was common pretransplant (57.2%). NODAT developed in 31.4% of recipients 1 year posttransplant. Participants with metabolic syndrome were more likely to develop NODAT compared with recipients without metabolic syndrome (34.4% vs. 27.4%, P=0.057). Recipients with increasing number of positive metabolic syndrome components were more likely to develop NODAT (metabolic syndrome score prevalence at 1 year: 0 components-0.0%, 1-24.2%, 2-29.3%, 3-31.0%, 4-34.8%, and 5-73.7%, P=0.001). After adjustment for demographics, age by decade (hazard ratio [HR] 1.34 [1.20-1.50], P<0.0001), African American race (HR 1.35 [1.01-1.82], P=0.043), cumulative prednisone dosage (HR 1.18 [1.07-1.30], P=0.001), and metabolic syndrome (HR 1.34 [1.00-1.79], P=0.047) were independent predictors of development of NODAT at 1 year posttransplant. In a multivariable analysis incorporating the individual metabolic syndrome components themselves as covariates, the only pretransplant metabolic syndrome component to remain an independent predictor of NODAT was low high-density lipoprotein (hazard ratio [HR] 1.37 [1.01-1.85], P=0.042).

CONCLUSIONS

Metabolic syndrome is an independent predictor for NODAT and is a possible target for intervention to prevent NODAT. Future studies to evaluate whether modification of metabolic syndrome factors pretransplant reduces NODAT development are needed.

Transient diabetes mellitus in a neonatal Thoroughbred foal

Objective – To describe the clinical presentation, treatment, and outcome of a neonatal foal diagnosed with transient Type 1 diabetes mellitus.

Case Summary – A 3‐day‐old Thoroughbred foal presented with a 24‐hour history of diarrhea and depression. Coronavirus particles were observed in the feces via electron microscopy. During hospitalization the foal developed hyperglycemia concomitantly with low insulin concentration and an adequate response to exogenous insulin therapy supported a diagnosis of Type 1 diabetes mellitus. The foal required SC insulin for 26 days, but developed complications associated with insulin therapy that resolved with appropriate care. On follow up assessment the foal was found to be a healthy euglycemic animal with normal insulin concentration at 11 months of age.

New or Unique Information Provided – To our knowledge this is the first report of Type 1 diabetes in this age group and the first report of transient neonatal diabetes mellitus in horses. Type 1 diabetes mellitus should be considered a differential diagnosis for hyperglycemia in equine neonates and that it can be transient and managed successfully.

Leptin treatment confers clinical benefit at multiple stages of virally induced type 1 diabetes in BB rats

The adipokine, leptin, regulates blood glucose and the insulin secretory function of beta cells, while also modulating immune cell function. We hypothesized that the dual effects of leptin may prevent or suppress the autoreactive destruction of beta cells in a virally induced rodent model of type 1 diabetes. Nearly 100% of weanling BBDR rats treated with the combination of an innate immune system activator, polyinosinic:polycytidylic acid (pIC), and Kilham rat virus (KRV) become diabetic within a predictable time frame. We utilized this model to test the efficacy of leptin in preventing diabetes onset, remitting new onset disease, and preventing autoimmune recurrence in diabetic rats transplanted with syngeneic islet grafts. High doses of leptin delivered via an adenovirus vector (AdLeptin) or alzet pump prevented diabetes in>90% of rats treated with pIC+KRV. The serum hyperleptinemia generated by this treatment was associated with decreased body weight, decreased non-fasting serum insulin levels, and lack of islet insulitis in leptin-treated rats. In new onset diabetics, hyperleptinemia prevented rapid weight loss and diabetic ketoacidosis, and temporarily restored euglycemia. Leptin treatment also prolonged the survival of syngeneic islets transplanted into diabetic BBDR rats. In diverse therapeutic settings, we found leptin treatment to have significant beneficial effects in modulating virally induced diabetes. These findings merit further evaluation of leptin as a potential adjunct therapeutic agent for treatment of human type 1 diabetes.

Study of transcriptional effects in Cis at the IFIH1 locus

BACKGROUND

The Thr allele at the non-synonymous single-nucleotide polymorphism (nsSNP) Thr946Ala in the IFIH1 gene confers risk for Type 1 diabetes (T1D). The SNP is embedded in a 236 kb linkage disequilibrium (LD) block that includes four genes: IFIH1, GCA, FAP and KCNH7. The absence of common nsSNPs in the other genes makes the IFIH1 SNP the strongest functional candidate, but it could be merely a marker of association, due to LD with a variant regulating expression levels of IFIH1 or neighboring genes.

METHODOLOGY/PRINCIPAL FINDINGS

We investigated the effect of the T1D-associated variation on mRNA transcript expression of these genes. Heterozygous mRNA from lymphoblastoid cell lines (LCLs), pancreas and thymus was examined by allelic expression imbalance, to detect effects in cis on mRNA expression. Using single-nucleotide primer extension, we found no difference between mRNA transcripts in 9 LCLs, 6 pancreas and 13 thymus samples, suggesting that GCA and FAP are not involved. On the other hand, KCNH7 was not expressed at a detectable level in all tissues examined. Moreover, the association of the Thr946Ala SNP with T1D is not due to modulation of IFIH1 expression in organs involved in the disease, pointing to the IFIH1 nsSNP as the causal variant.

CONCLUSIONS/SIGNIFICANCE

The mechanism of the association of the nsSNP with T1D remains to be determined, but does not involve mRNA modulation. It becomes necessary to study differential function of the IFIH1 protein alleles at Thr946Ala to confirm that it is responsible for the disease association.

Leptospirosis-associated disturbances of blood vessels, lungs and hemostasis

The frequency of massive pulmonary hemorrhages seems to be increasing in different geographic areas; however, there is no clear explanation for this trend. Although data on the pathogenesis of such complications are scarce, recent research indicates a potential role of autoimmunity and/or multifactorial mechanisms. However, much information is already available on the disturbance of hemostasis and blood vessels in leptospirosis-related literature, even if some contradictory concepts coexist. The purpose of this review is to integrate both new and classical information from human and animal studies on severe pulmonary forms of leptospirosis and disorders of hemostasis and blood vessels. We propose that the involvement of blood vessels in leptospirosis must be understood as a sepsis-like, diffuse process of endothelial activation/damage rather than as a classical systemic vasculitis. Pulmonary hemorrhages are most likely multifactorial and there has recently been evidence against the role of autoimmunity; however, further investigation of strain variations, exposure to hydrocarbons and association with renal dysfunction is required. Thrombocytopenia is a consistent feature of leptospirosis but it is not clear whether it is attributable to sepsis-related mechanisms. In addition, further investigation is required to define whether platelet function is activated or inhibited during severe leptospirosis.

Experimental encephalomyocarditis virus infection in small laboratory rodents

Encephalomyocarditis virus (EMCV) is a cardiovirus that belongs to the family Picornaviridae. EMCV is an important cause of acute myocarditis in piglets and of fetal death or abortion in pregnant sows. Small rodents, especially rats, have been suspected to be reservoir hosts or carriers. This virus also induces type 1 diabetes mellitus, encephalomyelitis, myocarditis, orchitis and/or sialodacryoadenitis in small laboratory rodents. This paper reviews the pathology and pathogenesis of experimental infection with EMCV in small laboratory rodents.

Visceral involvements and long-term sequelae in drug-induced hypersensitivity syndrome

Drug-induced hypersensitivity syndrome (DIHS) is a severe systemic reaction with several herpesvirus reactivations. Multiple organ failures appear during the course of the disease. The severity of DIHS is determined by the degree of visceral involvement. Autoimmune diseases also develop several months to years after the apparent clinical resolution of DIHS.

Rubella virus capsid protein: a small protein with big functions

Virus replication occurs in the midst of a life or death struggle between the virus and the infected host cell. To limit virus replication, host cells can activate a number of antiviral pathways, the most drastic of which is programmed cell death. Whereas large DNA viruses have the luxury of encoding accessory proteins whose main function is to interfere with host cell defences, the genomes of RNA viruses are not large enough to encode proteins of this type. Recent studies have revealed that proteins encoded by RNA viruses often play multiple roles in the battles between viruses and host cells. In this article, we discuss the many functions of the rubella virus capsid protein. This protein has well-defined roles in virus assembly, but recent research suggests that it also functions to modulate virus replication and block host cell defences.

The role of innate immune pathways in type 1 diabetes pathogenesis

PURPOSE OF REVIEW

Type 1 diabetes (T1D) is an autoimmune disease typically believed to result from malfunctions in adaptive immune response signaling which result in activation of self-reactive T cells. However, recent research has indicated components of the innate immune response as having a key role in the initiation of the autoimmune process of T1D. This review will highlight recent studies which examined the role of innate immune response signaling and the connections to T1D pathogenesis.

RECENT FINDINGS

Investigations indicate that components of innate immunity, including inflammation and Toll-like receptor signaling, are involved in pancreatic islet infiltration and insulitis. Recent studies examining the role of viral infections in T1D development also implicate innate immune response signaling in disease pathogenesis.

SUMMARY

Current research indicates that components of innate immune response signaling are involved in the initiation of the autoimmune process which results in the eventual destruction of beta cells during T1D pathogenesis. Continuing efforts by researchers to uncover the molecular pathways of innate immunity linked to T1D development could potentially lead to therapeutics capable of preventing and curing the autoimmune disease.

Gut barrier disruption by an enteric bacterial pathogen accelerates insulitis in NOD mice

AIMS/HYPOTHESIS

Increased exposure to enteric microbes as a result of intestinal barrier disruption is thought to contribute to the development of several intestinal inflammatory diseases; however, it less clear whether such exposure modulates the development of extra-intestinal inflammatory and autoimmune diseases. The goal of this study was to examine the potential role of pathogenic enteric microbes and intestinal barrier dysfunction in the pathogenesis of type 1 diabetes.

METHODS

Using NOD mice, we assessed: (1) intrinsic barrier function in mice at different ages by measuring serum levels of FITC-labelled dextran; and (2) the impact on insulitis development of infection by strains of an enteric bacterial pathogen (Citrobacter rodentium) either capable (wild-type) or incapable (lacking Escherichia coli secreted protein F virulence factor owing to deletion of the gene [DeltaespF]) of causing intestinal epithelial barrier disruption.

RESULTS

Here we demonstrate that prediabetic (12-week-old) NOD mice display increased intestinal permeability compared with non-obese diabetes-resistant and C57BL/6 mice. We also found that young (4-week-old) NOD mice infected with wild-type C. rodentium exhibited accelerated development of insulitis in concert with infection-induced barrier disruption. In contrast, insulitis development was not altered in NOD mice infected with the non-barrier-disrupting DeltaespF strain. Moreover, C. rodentium-infected NOD mice demonstrated increased activation and proliferation of pancreatic-draining lymph node T cells, including diabetogenic CD8(+) T cells, compared with uninfected NOD mice.

CONCLUSIONS/INTERPRETATION

This is the first demonstration that a loss of intestinal barrier integrity caused by an enteric bacterial pathogen results in the activation of diabetogenic CD8(+) T cells and modulates insulitis.

HLA class I molecules reflect an altered host proteome after influenza virus infection

Class I HLA sample and display peptides from thousands of endogenous proteins at the cell surface. During infection, the influenza virus modifies the host cell proteome by triggering host antiviral responses, hijacking host processes, and inhibiting host mRNA processing. In turn, the catalog of HLA class I peptides that decorate the surface of an infected cell is positioned to reflect an altered host cell proteome. To understand the host-encoded peptides presented by class I molecules after influenza infection, we compared by mass spectrometry (MS) the peptides eluted from the HLA of naive and infected cells. We identified 20 peptide ligands unique to infected cells and 347 peptides with increased presentation after infection. Infection with different influenza strains demonstrated that proteome changes are predominantly strain-specific, with few individual cellular interactions observed for multiple viral strains. Modeling by pathway analysis, however, revealed that strain specific host peptide changes represent different routes to the same destination; host changes mediated by influenza are found predominantly clustered around HLA-B, ACTB, HSP90AB1, CDK2, and ANXA2. The class I HLA proteome scanning of influenza-infected cells therefore indicates how divergent strains of influenza pursue alternate routes to access the same host cell processes.

Viren mit einzelsträngigem RNA-Genom in Plusstrangorientierung

Heute sind acht Virusfamilien bekannt, deren Vertreter eine einzelsträngige RNA in Plusstrangorientierung besitzen: Die Picornaviridae, Caliciviridae, Astroviridae und Hepeviren verfügen über Capside, die keine Hüllmembran aufweisen, wohingegen die Flaviviridae, Togaviridae, Arteriviridae und Coronaviridae durch membranumhüllte Partikel gekennzeichnet sind. Allen gemeinsam ist, dass sie ihre Genome als mRNA verwenden und davon ein oder mehrere Polyproteine synthetisieren, die im weiteren Verlauf durch virale oder auch zelluläre Proteasen in Einzelkomponenten gespalten werden. Die Viren verfügen über eine RNA-abhängige RNA-Polymerase, welche die Plusstrang-RNA sowie die als Zwischenprodukte der Replikation auftretenden Negativstränge übersetzt; dabei gehen die neuen genomischen RNA-Moleküle aus dem zweiten Transkriptionsschritt hervor. Die Einteilung in die unterschiedlichen Familien richtet sich nach Zahl, Größe, Lage und Orientierung der Virusgene auf der RNA, nach der Anzahl der unterschiedlichen Polyproteine, die während der Infektion synthetisiert werden, und nach dem Vorhandensein einer Hüllmembran als Teil der Virionen.

Immunology of beta-cell destruction

The pancreatic islet beta-cells are the target for an autoimmune process that eventually results in an inability to control blood glucose due to the lack of insulin. The different steps that eventually lead to the complete loss of the beta-cells are reviewed to include the very first step of a triggering event that initiates the development of beta-cell autoimmunity to the last step of appearance of islet-cell autoantibodies, which may mark that insulitis is about to form. The observations that the initial beta-cell destruction by virus or other environmental factors triggers islet autoimmunity not in the islets but in the draining pancreatic lymph nodes are reviewed along with possible basic mechanisms of loss of tolerance to islet autoantigens. Once islet autoimmunity is established the question is how beta-cells are progressively killed by autoreactive lymphocytes which eventually results in chronic insulitis. Many of these series of events have been dissected in spontaneously diabetic mice or rats, but controlled clinical trials have shown that rodent observations are not always translated into mechanisms in humans. Attempts are therefore needed to clarify the step 1 triggering mechanisms and the step to chronic autoimmune insulitis to develop evidence-based treatment approaches to prevent type 1 diabetes.

Prevalence and features of keratitis with quantitative polymerase chain reaction positive for cytomegalovirus

PURPOSE

To assess corneal scrapings and aqueous humor samples analyzed by polymerase chain reaction (PCR) that were positive for cytomegalovirus (CMV) in patients with keratitis of unknown origin and to investigate their clinical manifestations.

DESIGN

Retrospective, interventional case series.

PARTICIPANTS

Seventy-eight patients with epithelial (n=37), stromal (n=12), or endothelial keratitis (n=29) of unknown origin examined at the Osaka University Medical Hospital.

METHODS

Clinical examination and tears, corneal scrapings, and aqueous humor specimens were evaluated by real-time PCR for CMV.

MAIN OUTCOME MEASURES

Quantification of CMV DNA at the diagnosis of each type of keratitis with unknown origin and monitoring during the therapeutic course for CMV-positive cases.

RESULTS

No cases of epithelial or stromal keratitis had CMV DNA. Seven of 29 corneal endotheliitis cases (24.1%) were positive for CMV. Cytomegalovirus-positive cases of corneal endotheliitis characterized by localized corneal edema and keratic precipitates included 4 patients who had undergone penetrating keratoplasty and were refractory to the treatment for graft rejection and 3 patients with idiopathic endotheliitis. Cytomegalovirus DNA copy numbers were estimated and ranged from 6.3x10(4) to 3.6x10(6)/ml. In all positive cases, the numbers of CMV DNA copies decreased within weeks during treatment with systemic and topical ganciclovir (GCV) combined with a topical steroid. Five eyes (62.5%) had clinical improvement. In cases of endothelial keratitis, diabetes mellitus was significantly higher in patients positive for CMV (71.4%) than in patients negative for CMV (18.2%, P=0.016, chi-square test).

CONCLUSIONS

A total of 24.1% of cases with corneal edema of unknown origin were CMV positive and should be included in the differential diagnosis of idiopathic corneal endotheliitis or graft edema after penetrating keratoplasty, especially for bullous keratopathy. Real-time PCR for CMV, based on the diagnosis and monitoring of the clinical course, may be useful. Cytomegalovirus corneal endotheliitis requires early appropriate treatment using GCV. Because clinical remission after GCV may depend on the area of normal endothelium, early diagnosis and therapy are important for CMV corneal endotheliitis.

The rs1990760 polymorphism within the IFIH1 locus is not associated with Graves' disease, Hashimoto's thyroiditis and Addison's disease

Background

Three genes have been confirmed as major joint susceptibility genes for endocrine autoimmune disease:human leukocyte antigen class II, cytotoxic T-lymphocyte antigen 4 and protein tyrosine phosphatase non-receptor type 22. Recent studies showed that a genetic variation within the interferon induced helicase domain 1 (IFIH1) locus (rs1990760 polymorphism) is an additional risk factor in type 1 diabetes and Graves' disease (GD).

Methods

The aim of the present study was to investigate the role of the rs1990760 polymorphism within the IFIH1 gene in German patients with GD (n = 258), Hashimoto's thyroiditis (HT, n = 106), Addison's disease (AD, n = 195) and healthy controls (HC, n = 227) as well as in 55 GD families (165 individuals, German) and 100 HT families (300 individuals, Italian). Furthermore, the interaction between rs1990760 polymorphism with human leukocyte antigen (HLA) risk haplotype DQ2(DQA*0501-DQB*0201), the risk haplotypes DQ2/DQ8 (DQA*0301-DQB*0302) and the status of thyroglobulin antibody (TgAb), thyroid peroxidase antibody (TPOAb) and TSH receptor antibody (TRAb) in patients and families were analysed.

Results

No significant differences were found between the allele and genotype frequencies for rs1990760 IFIH1 polymorphism in patients with GD, HT, AD and HC. Also no differences were observed when stratifying the IFIH1 rs1990760 polymorphism for gender, presence or absence of thyroid antibodies (GD:TRAb and HT:TPOAb/TgAb) and HLA risk haplotypes (DQ2:for GD and HT, DQ2/DQ8:for AD). Furthermore the transmission analysis in GD and HT families revealed no differences in alleles transmission for rs1990760 IFIH1 from parents with or without HLA risk haplotype DQ2 to the affected offspring. In contrast, by dividing the HT parents according to the presence or absence of thyroid Ab titers, mothers and fathers both positive for TPOAb/TgAb overtransmitted the allele A of IFIH1 rs1990760 to their HT affected offspring (61.8% vs 38.2%;p = 0.05;corrected p [pc] = 0.1). However, these associations did not remain statistically significant after correction of the p-values.

Conclusion

In conclusion, our data suggest, no contribution from IFIH1 rs1990760 polymorphism to the pathogenesis of either Graves' disease, Hashimoto's thyroiditis or Addison's disease in our study populations. However, in order to exclude a possible influence of the studied polymorphism in specified subgroups within patients with autoimmune thyroid disease, further investigations in larger populations are needed.

The 'indirect' effects of cytomegalovirus infection

Cytomegalovirus (CMV) remains the most important infection in the immunocompromized host even in the era of effective therapy. CMV is usually acquired early in life and can be transmitted by contact with infected body fluids. In the immunocompetent population, primary infection is almost always of little clinical consequence. However, CMV infection in immunocompromized patients, especially those naive to CMV exposure, can cause tissue invasive disease, severe symptoms and/or death. However, beyond these direct effects, increasing in vitro evidence is accumulating that suggests CMV has many other effects on the host's immune response which may explain some of the detrimental consequences for the immunosuppressed patient, and may also be partially responsible for a variety of conditions in immunocompetent individuals. In its latent state, CMV employs several mechanisms to evade detection by the host's immune system. The virus also employs other methods to take advantage of activation of the immune system and replicate in sites of inflammation. This review focuses on the immunosuppressive and inflammatory mechanisms that have been attributed to CMV and will relate them to some of the clinical sequellae that have been associated with the indirect effects of CMV infection.

Lymphocyte proliferation in immune-mediated diseases

Defects in T cell homeostatic mechanisms can result in T cell lymphopenia, defined as decreased numbers of lymphocytes. Lymphopenia results in homeostatic proliferation in order to maintain T cell homeostasis. It has been proposed that homeostatic proliferation can expand the pool of autoreactive T cells that promote autoimmunity, and indeed recent studies have further substantiated this observation in both animal models and humans. Conversely, homeostatic proliferation can promote tumor immunity by allowing tumor-specific T cells to accumulate. In this review, we discuss how the outcome of homeostatic proliferation can function both in a deleterious manner in autoimmunity and a beneficial way in tumor immunity. We also discuss the roles of various cytokines and T regulatory cells that control homeostatic proliferation.

A case of fulminant type 1 diabetes with coxsackie B4 virus infection diagnosed by elevated serum levels of neutralizing antibody

A 39-year-old woman with hyperglycemia and ketonuria but with normal HbA1c level was diagnosed as having fulminant type 1 diabetes. The patient had 8-fold increase in the plasma titer of coxsackie B4 virus neutralizing antibody. Infection with coxsackie B4 virus was associated with fulminant type 1 diabetes.

The toll-like receptor signaling molecule Myd88 contributes to pancreatic beta-cell homeostasis in response to injury

Commensal flora and pathogenic microbes influence the incidence of diabetes in animal models yet little is known about the mechanistic basis of these interactions. We hypothesized that Myd88, an adaptor molecule in the Toll-like-receptor (TLR) pathway, regulates pancreatic beta-cell function and homeostasis. We first examined beta-cells histologically and found that Myd88-/- mice have smaller islets in comparison to C57Bl/6 controls. Myd88-/- mice were nonetheless normoglycemic both at rest and after an intra-peritoneal glucose tolerance test (IPGTT). In contrast, after low-dose streptozotocin (STZ) challenge, Myd88-/-mice had an abnormal IPGTT relative to WT controls. Furthermore, Myd88-/- mice suffer enhanced beta-cell apoptosis and have enhanced hepatic damage with delayed recovery upon low-dose STZ treatment. Finally, we treated WT mice with broad-spectrum oral antibiotics to deplete their commensal flora. In WT mice, low dose oral lipopolysaccharide, but not lipotichoic acid or antibiotics alone, strongly promoted enhanced glycemic control. These data suggest that Myd88 signaling and certain TLR ligands mediate a homeostatic effect on beta-cells primarily in the setting of injury.

Parameters influencing antigen-specific immunotherapy for Type 1 diabetes

Type 1 diabetes (T1D) is a T cell-mediated autoimmune disease in which the insulin producing beta cells are destroyed. Antigen-based immunotherapy provides an approach to selectively tolerize pathogenic beta cell-specific T cells, while leaving the remainder of the immune system intact. In this article, we discuss our group's experience in defining the parameters that impact the efficacy of beta cell antigen "vaccination" for the prevention and treatment of T1D.

Closing the circle between the bedside and the bench: Toll-like receptors in models of virally induced diabetes

Animal models provide many strategies to unravel the complex interplay of genetic, immunologic, and environmental factors involved in the pathogenesis of type 1A (autoimmune) diabetes. Diabetes can be studied at multiple levels, and new technological advancements provide insights into the functioning of organelle and cellular structures. The role of innate immunity in the response to environmental pathogens has provided possible biochemical and molecular mechanisms which can explain certain clinical events in diabetes. These investigations may uncover new therapies and strategies to prevent type 1A diabetes.

Cardioviruses are genetically diverse and cause common enteric infections in South Asian children

Cardioviruses cause enteric infections in mice and rats which when disseminated have been associated with myocarditis, type 1 diabetes, encephalitis, and multiple sclerosis-like symptoms. Cardioviruses have also been detected at lower frequencies in other mammals. The Cardiovirus genus within the Picornaviridae family is currently made up of two viral species, Theilovirus and Encephalomyocarditis virus. Until recently, only a single strain of cardioviruses (Vilyuisk virus within the Theilovirus species) associated with a geographically restricted and prevalent encephalitis-like condition had been reported to occur in humans. A second theilovirus-related cardiovirus (Saffold virus [SAFV]) was reported in 2007 and subsequently found in respiratory secretions from children with respiratory problems and in stools of both healthy and diarrheic children. Using viral metagenomics, we identified RNA fragments related to SAFV in the stools of Pakistani and Afghani children with nonpolio acute flaccid paralysis (AFP). We sequenced three near-full-length genomes, showing the presence of divergent strains of SAFV and preliminary evidence of a distant recombination event between the ancestors of the Theiler-like viruses of rats and those of human SAFV. Further VP1 sequencing showed the presence of five new SAFV genotypes, doubling the reported genetic diversity of human and animal theiloviruses combined. Both AFP patients and healthy children in Pakistan were found to be excreting SAFV at high frequencies of 9 and 12%, respectively. Further studies are needed to examine the roles of these highly common and diverse SAFV genotypes in nonpolio AFP and other human diseases.

Recent advances in childhood diabetes mellitus

Diabetes mellitus (DM) is a syndrome characterized by disturbed metabolism of carbohydrate, protein, and fat. It is a chronic metabolic disorder caused by an absolute or relative deficiency of insulin. It presents with very different medical and psychosocial issues in children.

Epidemiological studies indicate that there is gradual but steady increase in the incidence of both type 1 diabetes (T1DM) and type 2 diabetes (T2DM) in both developed and developing countries. The manifestations, therapy goals, clinical course, susceptibility to complications of diabetes differ among childhood cases.

T1DM accounts for the majority of cases of diabetes in children. Diabetic ketoacidosis may be the initial presentation of T1DM in many children particularly in Africa probably due to low level of awareness.

The focus of this review on T1DM is to provide an overview of the major advances in the aetiology, pathogenesis, and clinical management of newly diagnosed children and their subsequent management with the aim of ensuring optimal growth and development as well as preventing acute and chronic complications. The advances in insulin therapy and regimens and the presentation and management of diabetic ketoacidosis are discussed. The prospects for the cure of the disease are also highlighted in this review.

Infectious diseases and Type 1 diabetes in children

Type 1 diabetes (T1D) is an autoimmune disease triggered by environmental factors. Among those of infectious origin, viruses mostly associated to T1D are rubella virus, enteroviruses (Rotavirus, Coxackie B), Cytomegalovirus and mumps virus. The role of bacterial infections is still controversial, acting either as modulators or precipitating factors of an already started autoimmune process. Polymorphic genes of innate immunity, such as Toll-like receptors, nucleotide-binding oligomerization domain (NOD) 1 and NOD2 and mannose-binding lectin (MBL) genes, did not show a strict association with T1D onset, while protein tyrosine phosphatase (PTPN22), cytotoxic T-lymphocyte antigen (CTLA)4 and natural killer cells immunoglobulin-like receptor (KIR) genes appear to play an important role. However, the adaptive immune response genes (HLA) still provide the major contribution to T1D susceptibility. Here, we review the mechanism by which microorganisms might induce autoimmunity.

Rotavirus infection accelerates type 1 diabetes in mice with established insulitis

Infection modulates type 1 diabetes, a common autoimmune disease characterized by the destruction of insulin-producing islet beta cells in the pancreas. Childhood rotavirus infections have been associated with exacerbations in islet autoimmunity. Nonobese diabetic (NOD) mice develop lymphocytic islet infiltration (insulitis) and then clinical diabetes, whereas NOD8.3 TCR mice, transgenic for a T-cell receptor (TCR) specific for an important islet autoantigen, show more rapid diabetes onset. Oral infection of infant NOD mice with the monkey rotavirus strain RRV delays diabetes development. Here, the effect of RRV infection on diabetes development once insulitis is established was determined. NOD and NOD8.3 TCR mice were inoculated with RRV aged > or = 12 and 5 weeks, respectively. Diabetes onset was significantly accelerated in both models (P < 0.024), although RRV infection was asymptomatic and confined to the intestine. The degree of diabetes acceleration was related to the serum antibody titer to RRV. RRV-infected NOD mice showed a possible trend toward increased insulitis development. Infected males showed increased CD8(+) T-cell proportions in islets. Levels of beta-cell major histocompatibility complex class I expression and islet tumor necrosis factor alpha mRNA were elevated in at least one model. NOD mouse exposure to mouse rotavirus in a natural experiment also accelerated diabetes. Thus, rotavirus infection after beta-cell autoimmunity is established affects insulitis and exacerbates diabetes. A possible mechanism involves increased exposure of beta cells to immune recognition and activation of autoreactive T cells by proinflammatory cytokines. The timing of infection relative to mouse age and degree of insulitis determines whether diabetes onset is delayed, unaltered, or accelerated.

Mediators and mechanisms of pancreatic beta-cell death in type 1 diabetes

Type 1 diabetes mellitus (T1D) is characterized by severe insulin deficiency resulting from chronic and progressive destruction of pancreatic beta-cells by the immune system. The triggering of autoimmunity against the beta-cells is probably caused by environmental agent(s) acting in the context of a predisposing genetic background. Once activated, the immune cells invade the islets and mediate their deleterious effects on beta-cells via mechanisms such as Fas/FasL, perforin/granzyme, reactive oxygen and nitrogen species and pro-inflammatory cytokines. Binding of cytokines to their receptors on the beta-cells activates MAP-kinases and the transcription factors STAT-1 and NFkappa-B, provoking functional impairment, endoplasmic reticulum stress and ultimately apoptosis. This review discusses the potential mediators and mechanisms leading to beta-cell destruction in T1D.

The association between the IFIH1 locus and type 1 diabetes

AIMS/HYPOTHESIS

We set out to validate a recently reported type 1 diabetes association from the IFIH1 gene variation in an independent cohort from a population of mixed European descent.

METHODS

We genotyped five single-nucleotide polymorphisms in the IFIH1 locus, i.e. rs2111485, rs1990760, rs3747517, rs17783344 and rs984971589, in 589 type 1 diabetes nuclear family trios (1,767 individuals).

RESULTS

This study independently replicated the reported genetic association using a family-based approach.

CONCLUSIONS/INTERPRETATION

The reported type 1 diabetes association is from a linkage disequilibrium region including three candidate genes, i.e. FAP, IFIH1 and GCA. Further variant discovery and fine mapping could help clarify a novel type 1 diabetes mechanism.

Proposal open for discussion: defining agreed diagnostic procedures in experimental diabetes research

BACKGROUND

Animal experimentation has a long tradition in diabetes research and has provided invaluable benefits with regard to insulin discovery and treatment assessment.

METHODS

The review focuses on chemical-induced diabetes in rats and surveys the protocols of diabetes induction, diabetes diagnosis, and glucose tolerance evaluation in a selection of recent research.

RESULTS

This brief review of techniques in experimental diabetes highlights that there is no uniformity, whereas standardisation of procedures is desirable so that comparability will exist among experiments carried out in different settings.

CONCLUSIONS

On this basis, questions are put and standards are proposed. It would be a platform to promote the exchange of ideas through expert consultation about practical issues related to animal research and a basis on which standards can be set according to user requirements and animal respect.

Toward cell-based therapy of type I diabetes

Type 1 diabetes (T1D) is an autoimmune disease that results from the destruction of insulin-producing pancreatic islet cells owing to the aggressive effector function of autoreactive T cells. In addition to lifetime supply of exogenous insulin, whole-pancreas or islet transplantation is presently the only alternative therapy for severely ill patients. Here, we discuss the current status of the development of cell-based therapies that are based on essentially two options, i.e. replacement of islet cells by islet-like cells derived from embryonic or adult stem cells, and re-establishment of immunological tolerance to islet self-antigens through regulatory T cells and/or tolerance-promoting monocyte-derived cells. A combination of both approaches will be required to turn cell-based therapy of T1D into clinical success.

The effect of birth order and parental age on the risk of type 1 and 2 diabetes among young adults

AIMS/HYPOTHESIS

The aim of this study was to examine the effects of birth order and parental age on the risk of type 1 and type 2 diabetes among Finnish individuals aged 15-39 years.

METHODS

Data on all cases of type 1 diabetes (n = 1,345) and type 2 diabetes (n = 1,072), diagnosed between 1992 and 1996, were collected from four sources: standardised national reports from diabetes nurses, the National Hospital Discharge Register, the Drug Prescription Register and the Drug Reimbursement Register. Information on matched controls and the family members of all study subjects were obtained from the National Population Registry. The odds ratios (ORs) for both types of diabetes were estimated using a conditional logistic regression model.

RESULTS

There was a U-shaped relationship between maternal age and the risk of type 2 diabetes in the offspring: the risk was higher in children born to young and old mothers compared with children born to mothers aged around 30 years. The children born second (OR 0.76, 95% CI 0.62-0.94), third (OR 0.73, 95% CI 0.55-0.95), or fourth (OR 0.66, 95% CI 0.47-0.94) had a lower risk of type 2 diabetes than the first-born children. Maternal age, paternal age, and birth order did not have an effect on the risk of type 1 diabetes in the individuals aged 15-39 years at the time of diagnosis.

CONCLUSIONS/INTERPRETATION

Maternal age and birth order are both associated with the risk of early-onset type 2 diabetes. However, part of these associations may be due to low birthweight. In this study neither parental age nor birth order showed a significant association with the risk of type 1 diabetes diagnosed after 15 years of age.

Rotavirus infections and development of type 1 diabetes: an evasive conundrum

Type 1 diabetes (T1D) is an organ-specific autoimmune disease caused by altered immune tolerance to specific proteins leading to a selective destruction of insulin-producing beta cells in genetically predisposed individuals. T1D is likely to be triggered by environmental factors, including virus infections in genetically predisposed individuals. Rotaviruses are the main cause of severe diarrhea among children worldwide, but they seem to have a role also in T1D induction. Epidemiological data may be consistent with a similar hypothesis. Mechanisms hypothesized include molecular mimicry, bystander activation (with or without epitope spreading), and viral persistence. In this review the authors analyze the factors accounting for rotavirus ability to prime islet autoimmunity and cause T1D. A thorough comprehension of their potential pathogenetic mechanisms may allow preventive strategies to be designed.

Rotavirus infection of infant and young adult nonobese diabetic mice involves extraintestinal spread and delays diabetes onset

Rotaviruses have been implicated as a possible viral trigger for exacerbations in islet autoimmunity, suggesting they might modulate type 1 diabetes development. In this study, the ability of rotavirus strain RRV to infect the pancreas and affect insulitis and diabetes was examined in nonobese diabetic (NOD) mice, an experimental model of type 1 diabetes. Mice were inoculated either orally or intraperitoneally as infants or young adults. In infant mice inoculated orally, rotavirus antigen was detected in pancreatic macrophages outside islets and infectious virus was found in blood cells, pancreas, spleen, and liver. Extraintestinal RRV spread and pancreatic presence of infectious virus also occurred in intraperitoneally inoculated infant and adult mice. The initiation of insulitis was unaltered by infection. The onset of diabetes was delayed in infant mice inoculated orally and infant and adult mice inoculated intraperitoneally. In contrast, adult mice inoculated orally showed no evidence of pancreatic RRV, the lowest rate of detectable RRV replication, and no diabetes modulation. Thus, the ability of RRV infection to modulate diabetes development in infant and young adult NOD mice was related to the overall extent of detectable virus replication and the presence of infectious virus extraintestinally, including in the pancreas. These studies show that RRV infection of infant and young adult NOD mice provides significant protection against diabetes. As these findings do not support the hypothesis that rotavirus triggers autoimmunity related to type 1 diabetes, further research is needed to resolve this issue.