A search for the presence of the enteroviral capsid protein VP1 in pancreases of patients with type 1 (insulin-dependent) diabetes and pancreases and hearts of infants who died of coxsackieviral myocarditis

[Lethal lymphocytic myocarditis-an underestimated diagnosis in infancy and childhood?]

In the past, histological diagnosis of (post-)viral myocarditis was based on the so-called Dallas criteria, which have been criticized because of high interobserver variability and sampling error. Immunohistochemical qualification and quantification of interstitial intramyocardial leucocytes was established and standard values concerning adults were published. Fatal casualties due to a viral myocarditis are rare as far as babies and children are concerned (sudden unexpected death in infancy; SUDI). Cases of sudden unexpected death in the first year of life are frequently regarded as sudden infant death syndrome (SIDS). To diagnose myocarditis when there are only single focal lymphocytic infiltrates in the myocardium, the number of samples taken by autopsy is relevant. But even in babies, immunohistochemical qualification and quantification of interstitial lymphocytes and macrophages can lead to standard values allowing diagnosis of myocarditis. Depending on the course of a viral infection, molecular pathological detection of viral genome in the myocardium is possible to support the diagnosis. Using the mentioned methods gradually, there are more cases of suspected SIDS, which are in fact cases of virus-induced myocarditis as cause of death. Primary enteroviruses (coxsackie viruses) and adenoviruses were found but also Epstein-Barr virus and PVB-19.

Bi-glandular and persistent enterovirus infection and distinct changes of the pancreas in slowly progressive type 1 diabetes mellitus

In slowly progressive type 1 diabetes mellitus (SPIDDM), the pancreas shows sustained islet inflammation, pancreatitis, pancreatic acinar cell metaplasia/dysplasia (ADM), and intraepithelial neoplasia (PanIN), a precancerous lesion. The mechanisms underlying these changes remain unclear. The presence of enterovirus (EV) encoded-capsid protein 1 (VP1) and -2A protease (2A^pro) and the innate immune responses of the pancreas were studied using immunohistochemistry and in situ hybridization in 12 SPIDDM and 19 non-diabetic control pancreases. VP1, 2A^pro, and EV-RNA were detected in islets and the exocrine pancreas in all SPIDDM pancreases. Innate immune receptor, melanoma differentiation-associated gene 5 (MDA5), and interferon (IFN)-beta1 were intensified in the islets of SPIDDM patients with short disease duration. However, expressions of MDA5 and IFN-beta1were suppressed in those with longer disease duration. CD3⁺ T cell infiltration was observed in the VP1- and insulin-positive islets (insulitis) and exocrine acinar cells. CD11c⁺ dendritic cells (DCs) in islets were scarce in long-term SPIDDM. This study showed the consistent presence of EV, suggesting an association with inflammatory changes in the endocrine and exocrine pancreas in SPIDDM. Suppressed expressions of MDA5 and IFN-beta1, as well as decreased numbers of DCs in the host cells, may contribute to persistent EV infection and induction of ADM/PanIN lesions, which may potentially provide a scaffold for pancreatic neoplasms.

Characterisation of enterovirus RNA detected in the pancreas and other specimens of live patients with newly diagnosed type 1 diabetes in the DiViD study

AIMS/HYPOTHESIS

The Diabetes Virus Detection (DiViD) study is the first study to laparoscopically collect pancreatic tissue and purified pancreatic islets together with duodenal mucosa, serum, peripheral blood mononuclear cells (PBMCs) and stools from six live adult patients (age 24-35 years) with newly diagnosed type 1 diabetes. The presence of enterovirus (EV) in the pancreatic islets of these patients has previously been reported.

METHODS

In the present study we used reverse transcription quantitative real-time PCR (RT-qPCR) and sequencing to characterise EV genomes present in different tissues to understand the nature of infection in these individuals.

RESULTS

All six patients were found to be EV-positive by RT-qPCR in at least one of the tested sample types. Four patients were EV-positive in purified islet culture medium, three in PBMCs, one in duodenal biopsy and two in stool, while serum was EV-negative in all individuals. Sequencing the 5' untranslated region of these EVs suggested that all but one belonged to enterovirus B species. One patient was EV-positive in all these sample types except for serum. Sequence analysis revealed that the virus strain present in the isolated islets of this patient was different from the strain found in other sample types. None of the islet-resident viruses could be isolated using EV-permissive cell lines.

CONCLUSIONS/INTERPRETATION

EV RNA can be frequently detected in various tissues of patients with type 1 diabetes. At least in some patients, the EV strain in the pancreatic islets may represent a slowly replicating persisting virus.

Application Route and Immune Status of the Host Determine Safety and Oncolytic Activity of Oncolytic Coxsackievirus B3 Variant PD-H

The coxsackievirus B3 strain PD-0 has been proposed as a new oncolytic virus for the treatment of colorectal carcinoma. Here, we generated a cDNA clone of PD-0 and analyzed the virus PD-H, newly generated from this cDNA, in xenografted and syngenic models of colorectal cancer. Replication and cytotoxic assays revealed that PD-H replicated and lysed colorectal carcinoma cell lines in vitro as well as PD-0. Intratumoral injection of PD-H into subcutaneous DLD-1 tumors in nude mice resulted in strong inhibition of tumor growth and significantly prolonged the survival of the animals, but virus-induced systemic infection was observed in one of the six animals. In a syngenic mouse model of subcutaneously growing Colon-26 tumors, intratumoral administration of PD-H led to a significant reduction of tumor growth, the prolongation of animal survival, the prevention of tumor-induced cachexia, and the elevation of CD3+ and dendritic cells in the tumor microenvironment. No virus-induced side effects were observed. After intraperitoneal application, PD-H induced weak pancreatitis and myocarditis in immunocompetent mice. By equipping the virus with target sites of miR-375, which is specifically expressed in the pancreas, organ infections were prevented. Moreover, employment of this virus in a syngenic mouse model of CT-26 peritoneal carcinomatosis resulted in a significant reduction in tumor growth and an increase in animal survival. The results demonstrate that the immune status of the host, the route of virus application, and the engineering of the virus with target sites of suitable microRNAs are crucial for the use of PD-H as an oncolytic virus.

Development of a new mouse model for coxsackievirus-induced myocarditis by attenuating coxsackievirus B3 virulence in the pancreas

AIMS

The coxsackievirus B3 (CVB3) mouse myocarditis model is the standard model for investigation of virus-induced myocarditis but the pancreas, rather than the heart, is the most susceptible organ in mouse. The aim of this study was to develop a CVB3 mouse myocarditis model in which animals develop myocarditis while attenuating viral infection of the pancreas and the development of severe pancreatitis.

METHODS AND RESULTS

We developed the recombinant CVB3 variant H3N-375TS by inserting target sites (TS) of miR-375, which is specifically expressed in the pancreas, into the 3'UTR of the genome of the pancreo- and cardiotropic CVB3 variant H3. In vitro evaluation showed that H3N-375TS was suppressed in pancreatic miR-375-expressing EndoC-βH1 cells >5 log10, whereas its replication was not suppressed in isolated primary embryonic mouse cardiomyocytes. In vivo, intraperitoneal (i.p.) administration of H3N-375TS to NMRI mice did not result in pancreatic or cardiac infection. In contrast, intravenous (i.v.) administration of H3N-375TS to NMRI and Balb/C mice resulted in myocardial infection and acute and chronic myocarditis, whereas the virus was not detected in the pancreas and the pancreatic tissue was not damaged. Acute myocarditis was characterized by myocardial injury, inflammation with mononuclear cells, induction of proinflammatory cytokines, and detection of replicating H3N-375TS in the heart. Mice with chronic myocarditis showed myocardial fibrosis and persistence of H3N-375TS genomic RNA but no replicating virus in the heart. Moreover, H3N-375TS infected mice showed distinctly less suffering compared with mice that developed pancreatitis and myocarditis after i.p. or i.v application of control virus.

CONCLUSION

In this study, we demonstrate that by use of the miR-375-sensitive CVB3 variant H3N-375TS, CVB3 myocarditis can be established without the animals developing severe systemic infection and pancreatitis. As the H3N-375TS myocarditis model depends on pancreas-attenuated H3N-375TS, it can easily be used in different mouse strains and for various applications.

Coxsackievirus B3-Its Potential as an Oncolytic Virus

Oncolytic virotherapy represents one of the most advanced strategies to treat otherwise untreatable types of cancer. Despite encouraging developments in recent years, the limited fraction of patients responding to therapy has demonstrated the need to search for new suitable viruses. Coxsackievirus B3 (CVB3) is a promising novel candidate with particularly valuable features. Its entry receptor, the coxsackievirus and adenovirus receptor (CAR), and heparan sulfate, which is used for cellular entry by some CVB3 variants, are highly expressed on various cancer types. Consequently, CVB3 has broad anti-tumor activity, as shown in various xenograft and syngeneic mouse tumor models. In addition to direct tumor cell killing the virus induces a strong immune response against the tumor, which contributes to a substantial increase in the efficiency of the treatment. The toxicity of oncolytic CVB3 in healthy tissues is variable and depends on the virus strain. It can be abrogated by genetic engineering the virus with target sites of microRNAs. In this review, we present an overview of the current status of the development of CVB3 as an oncolytic virus and outline which steps still need to be accomplished to develop CVB3 as a therapeutic agent for clinical use in cancer treatment.

miR-375- and miR-1-Regulated Coxsackievirus B3 Has No Pancreas and Heart Toxicity But Strong Antitumor Efficiency in Colorectal Carcinomas

Coxsackievirus B3 (CVB3) has strong oncolytic activity in colorectal carcinoma but it also infects the pancreas and the heart. To improve the safety of the virus, here we investigated whether pancreas and cardiac toxicity can be prevented by insertion of target sites (TS), which are complementary to miR-375 and miR-1 into the viral genome. Although miR-375 and miR-1 are abundantly expressed in the pancreas and in the heart, respectively, their expression levels are low in colorectal carcinomas, which allows the carcinomas to be selectively attacked. To investigate the importance of the microRNAs, two viruses were engineered, H3N-375TS containing only miR-375TS and H3N-375/1TS containing miR-375TS and miR-1TS. In vitro, both viruses replicated in and lysed colorectal carcinoma cells, similar to a nontargeted control virus H3N-39TS, whereas they were strongly attenuated in cell lines transiently or endogenously expressing the corresponding microRNAs. In vivo, the control virus H3N-39TS induced strong infection of the pancreas and the heart, which led to fatal disease within 4 days after a single intratumoral virus injection in mice xenografted with colorectal DLD-1 cell tumors. In contrast, three intratumoral injections of H3N-375TS or H3N-375/1TS failed to induce virus-induced sickness. In the animals, both viruses were completely ablated from the pancreas and H3N-375/1TS was also ablated from the heart, whereas the cardiac titers of H3N-375TS were strongly reduced. Long-term investigations of the DLD-1 tumor model confirmed lack of virus-induced adverse effects in H3N-375TS- and H3N-375/1TS-treated mice. There was no mortality, and the pancreas and the heart were free of pathological alterations. Regarding the therapeutic efficiency, the treated animals showed high and long-lasting H3N-375TS and H3N-375/1TS persistence in the tumor and significantly slower tumor growth. These data demonstrate that miR-375- and miR-1-mediated virus detargeting from the pancreas and heart is a highly effective strategy to prevent toxicity of oncolytic CVB3.

Association Between Enterovirus Infection and Type 1 Diabetes Risk: A Meta-Analysis of 38 Case-Control Studies

OBJECTIVE

The association between enterovirus infection and type 1 diabetes (T1D) is controversial, and this meta-analysis aimed to explore the correlation.

METHODS

PubMed, Embase, Web of Science, and Cochrane Database were searched from inception to April 2020. Studies were included if they could provide sufficient information to calculate odds ratios and 95% confidence intervals. All analyses were performed using STATA 15.1.

RESULTS

Thirty-eight studies, encompassing 5921 subjects (2841 T1D patients and 3080 controls), were included. The pooled analysis showed that enterovirus infection was associated with T1D (P < 0.001). Enterovirus infection was correlated with T1D in the European (P < 0.001), African (P = 0.002), Asian (P = 0.001), Australian (P = 0.011), and Latin American (P = 0.002) populations, but no conclusion could be reached for North America. The association between enterovirus infection and T1D was detected in blood and tissue samples (both P < 0.001); no association was found in stool samples.

CONCLUSION

Our findings suggest that enterovirus infection is associated with T1D.

The first versatile human iPSC-based model of ectopic virus induction allows new insights in RNA-virus disease

A detailed description of pathophysiological effects that viruses exert on their host is still challenging. For the first time, we report a highly controllable viral expression model based on an iPS-cell line from a healthy human donor. The established viral model system enables a dose-dependent and highly localized RNA-virus expression in a fully controllable environment, giving rise for new applications for the scientific community.

Unique Inflammatory Changes in Exocrine and Endocrine Pancreas in Enterovirus-Induced Fulminant Type 1 Diabetes

CONTEXT

There are scant reports on the pathological changes of the exocrine and endocrine pancreas in fulminant type 1 diabetes mellitus (FT1DM).

OBJECTIVE

To clarify the distinct pathological changes in the exocrine as well as the endocrine pancreas shortly after onset of diabetes in FT1DM.

DESIGN

The exocrine and endocrine pancreases of 3 patients with FT1DM and 17 nondiabetic controls were immunohistochemically examined for islet and exocrine tissue inflammation, infiltrating mononuclear cell (MNC) CD subtype, enterovirus capsid protein 1 (VP1) localization, and CXC chemokine ligand 10 (CXCL10) and CXC chemokine receptor 3 (CXCR3) expressions.

RESULTS

The median frequency of insulitis in the 3 FT1DM pancreases was 60%. In the nondiabetic control pancreases, no insulitis was observed. In the islets of FT1DM, the numbers of CD45+, CD3+, CD8+, CD68+, and CD11c+ MNCs were significantly higher than those of the control group. In the exocrine pancreas of FT1DM, the numbers of CD3+ T cells, CD8+ T cells, CD68+ macrophages, and CD11c+ dendritic cells were significantly higher than those of the control group. Infiltrating CD8+ T cells, CD68+ macrophages, and CD11c+ dendritic cells were observed around exocrine acinar cells in FT1DM. There was a close association between VP1 and CXCL10 expression in pancreatic exocrine ductal cells and acinar cells as well as islet cells in FT1DM. CXCL10+ exocrine cells were surrounded by CXCR3+ T cells.

CONCLUSION

The pathological findings suggested that suppression of the activated CXCL10-CXCR3 axis in the exocrine as well as the endocrine pancreas is a novel therapeutic target in FT1DM and possibly in enterovirus-associated acute-onset type 1 diabetes.

Echovirus 6 Infects Human Exocrine and Endocrine Pancreatic Cells and Induces Pro-Inflammatory Innate Immune Response

Human enteroviruses (HEV), especially coxsackievirus serotype B (CVB) and echovirus (E), have been associated with diseases of both the exocrine and endocrine pancreas, but so far evidence on HEV infection in human pancreas has been reported only in islets and ductal cells. This study aimed to investigate the capability of echovirus strains to infect human exocrine and endocrine pancreatic cells. Infection of explanted human islets and exocrine cells with seven field strains of E6 caused cytopathic effect, virus titer increase and production of HEV protein VP1 in both cell types. Virus particles were found in islets and acinar cells infected with E6. No cytopathic effect or infectious progeny production was observed in exocrine cells exposed to the beta cell-tropic strains of E16 and E30. Endocrine cells responded to E6, E16 and E30 by upregulating the transcription of interferon-induced with helicase C domain 1 (IF1H1), 2′-5′-oligoadenylate synthetase 1 (OAS1), interferon-β (IFN-β), chemokine (C–X–C motif) ligand 10 (CXCL10) and chemokine (C–C motif) ligand 5 (CCL5). Echovirus 6, but not E16 or E30, led to increased transcription of these genes in exocrine cells. These data demonstrate for the first time that human exocrine cells represent a target for E6 infection and suggest that certain HEV serotypes can replicate in human pancreatic exocrine cells, while the pancreatic endocrine cells are permissive to a wider range of HEV.

Persistence of Coxsackievirus B4 in pancreatic ductal-like cells results in cellular and viral changes

INTRODUCTION

Although known as cytolytic viruses, group B coxackieviruses (CVB) are able to establish a persistent infection in vitro and in vivo. Viral persistence has been reported as a key mechanism in the pathogenesis of CVB-associated chronic diseases such as type 1 diabetes (T1D). The impact of CVB4 persistence on human pancreas ductal-like cells was investigated.

METHODS

A persistent CVB4 infection was established in ductal-like cells. PDX-1 expression, resistance to CVB4-induced lysis and CAR expression were evaluated. The profile of cellular microRNAs (miRNAs) was investigated through miRNA-sequencing. Viral phenotypic changes were examined, and genomic modifications were assessed by sequencing of the viral genome.

RESULTS

The CVB4 persistence in ductal-like cells was productive, with continuous release of infectious particles. Persistently infected cells displayed a resistance to CVB4-induced lysis upon superinfection and expression of PDX-1 and CAR was decreased. These changes were maintained even after virus clearance. The patterns of cellular miRNA expression in mock-infected and in CVB4-persistently infected ductal-like cells were clearly different. The persistent infection-derived virus (PIDV) was still able to induce cytopathic effect but its plaques were smaller than the parental virus. Several mutations appeared in various PIDV genome regions, but amino acid substitutions did not affect the predicted site of interaction with CAR.

CONCLUSION

Cellular and viral changes occur during persistent infection of human pancreas ductal-like cells with CVB4. The persistence of cellular changes even after virus clearance supports the hypothesis of a long-lasting impact of persistent CVB infection on the cells.

Differential cell autonomous responses determine the outcome of coxsackievirus infections in murine pancreatic α and β cells

Type 1 diabetes (T1D) is an autoimmune disease caused by loss of pancreatic β cells via apoptosis while neighboring α cells are preserved. Viral infections by coxsackieviruses (CVB) may contribute to trigger autoimmunity in T1D. Cellular permissiveness to viral infection is modulated by innate antiviral responses, which vary among different cell types. We presently describe that global gene expression is similar in cytokine-treated and virus-infected human islet cells, with up-regulation of gene networks involved in cell autonomous immune responses. Comparison between the responses of rat pancreatic α and β cells to infection by CVB5 and 4 indicate that α cells trigger a more efficient antiviral response than β cells, including higher basal and induced expression of STAT1-regulated genes, and are thus better able to clear viral infections than β cells. These differences may explain why pancreatic β cells, but not α cells, are targeted by an autoimmune response during T1D.

DOI:http://dx.doi.org/10.7554/eLife.06990.001

Type 1 diabetes is caused by a person's immune system attacking the cells in their pancreas that produce insulin. This eventually kills off so many of these cells—known as beta cells—that the pancreas is unable to make enough insulin. As a result, individuals with type 1 diabetes must inject insulin to help their bodies process sugars. One of the mysteries of type 1 diabetes is why the beta cells in the pancreas are killed by the immune system while neighboring alpha cells, which produce the hormone glucagon, are spared.

Scientists suspect a combination of genetic and environmental factors contributes to type 1 diabetes. Certain viruses, including one called Coxsackievirus, appear to trigger type 1 diabetes in susceptible individuals. Other factors may also make these individuals more likely to develop the disease. For example, they may ‘express’ genes that are thought to increase the risk of type 1 diabetes, many of which control how the immune system responds to viral infections. These genes may make susceptible individuals experience excessive inflammation, because inflammation is what ultimately kills off the beta cells.

Now, Marroqui, Lopes, dos Santos et al. provide evidence that suggests why the alpha cells are spared the immune onslaught in type 1 diabetes. In initial experiments, clusters of cells—known as islets—from the human pancreas were either exposed to small proteins that cause inflammation or infected with the Coxsakievirus. Both events caused a similar increase in the expression of particular immune response genes in the islets. This indicates that these islet cells are able to react to the virus and trigger a first line of defense, which will be further boosted when the immune system is subsequently called into action.

Islets contain both alpha and beta cells, and so further experiments on alpha and beta cells from rats investigated whether the two cell types respond differently when infected by the Coxsakievirus. The results revealed that alpha cells boost the expression of the genes needed to clear the virus to a greater extent than the beta cells, and so respond more efficiently to the virus. Therefore, an infection is more likely to establish itself in the beta cells and consequently trigger inflammation and the immune system's attack on the cells.

These observations explain one of the puzzling questions in the diabetes field and reinforce the possibility that a long-standing viral infection in beta cells—which seem to have a limited capacity to clear viral infections—may be one of the mechanisms leading to progressive beta cell destruction in type 1 diabetes. This knowledge will help in the search for ways to protect beta cells against both viral infections and the consequent immune assault.

DOI:http://dx.doi.org/10.7554/eLife.06990.002

Establishment of a panel of in-house polyclonal antibodies for the diagnosis of enterovirus infections

The aim of this study was to establish a reliable method of virus detection for the diagnosis of critical enterovirus infections such as acute infective encephalitis, encephalomyelitis and myocarditis. Because histopathological and immunohistochemical analyses of paraffin-embedded tissues play an important role in recognizing infectious agents in tissue samples, six in-house polyclonal antibodies raised against three representative enteroviruses using an indirect immunofluorescence assay and immunohistochemistry were examined. This panel of polyclonal antibodies recognized three serotypes of enterovirus. Two of the polyclonal antibodies were raised against denatured virus particles from enterovirus A71, one was raised against the recombinant VP1 protein of coxsackievirus B3, and the other for poliovirus type 1 were raised against denatured virus particles, the recombinant VP1 protein and peptide 2C. Western blot analysis revealed that each of these antibodies recognized the corresponding viral antigen and none cross-reacted with non-enteroviruses within the family Picornaviridae. However, all cross-reacted to some extent with the antigens derived from other serotypes of enterovirus. Indirect immunofluorescence assay and immunohistochemistry revealed that the virus capsid and non-structural proteins were localized in the cytoplasm of affected culture cells, and skeletal muscles and neurons in neonatal mice experimentally-infected with human enterovirus. The antibodies also recognized antigens derived from recent clinical isolates of enterovirus A71, coxsackievirus B3 and poliovirus. In addition, immunohistochemistry revealed that representative antibodies tested showed the same recognition pattern according to each serotype. Thus, the panel of in-house anti-enterovirus polyclonal antibodies described herein will be an important tool for the screening and pathological diagnosis for enterovirus infections, and may be useful for the classification of different enterovirus serotypes, including coxsackieviruses A and B, echoviruses, enterovirus A71 and poliovirus.

Tissue tropism, pathology and pathogenesis of enterovirus infection

Enteroviruses are very common and cause infections with a diverse array of clinical features. Enteroviruses are most frequently considered by practising pathologists in cases of aseptic meningitis, encephalitis, myocarditis and disseminated infections in neonates and infants. Congenital infections have been reported and transplacental transmission is thought to occur. Although skin biopsies during hand, foot and mouth disease are infrequently obtained, characteristic dermatopathological findings can be seen. Enteroviruses have been implicated in lower respiratory tract infections. This review highlights histopathological features of enterovirus infection and discusses diagnostic modalities for formalin-fixed paraffin-embedded tissues and their associated pitfalls. Immunohistochemistry can detect enterovirus antigen within cells of affected tissues; however, assays can be non-specific and detect other viruses. Molecular methods are increasingly relied upon but, due to the high frequency of asymptomatic enteroviral infections, clinical-pathological correlation is needed to determine significance. Of note, diagnostic assays on central nervous system or cardiac tissues from immunocompetent patients with prolonged disease courses are most often negative. Histopathological, immunohistochemical and molecular studies performed on clinical specimens also provide insight into enteroviral tissue tropism and pathogenesis.

Enteroviruses as causative agents in type 1 diabetes: loose ends or lost cause?

Considerable evidence implies that an enteroviral infection may accelerate or precipitate type 1 diabetes (T1D) in some individuals. However, causality is not proven. We present and critically assess evidence suggesting that islet β cells can become infected with enterovirus, and argue that this may result in one of several consequences. Occasionally, a fully lytic infection may arise and this culminates in fulminant diabetes. Alternatively, an atypical persistent infection develops which can be either benign or promote islet autoimmunity. We propose a model in which the 'strength' of the β cell response to the establishment of a persistent enteroviral infection determines the final disease outcome.

Pancreatic pathology in type 1 diabetes mellitus

Type 1 diabetes is a multifactorial disease resulting from a complex interplay between host genetics, the immune system and the environment, that culminates in the destruction of insulin-producing beta cells. The incidence of type 1 diabetes is increasing at an alarming rate, especially in children under the age of 5 (Gepts in Diabetes 14(10):619-613, 1965; Foulis et al. in Lancet 29(5):267-274, 1986; Gamble, Taylor and Cumming in British Medical Journal 4(5887):260-262 1973). Genetic predisposition, although clearly important, cannot explain this rise, and so, it has been proposed that changes in the 'environment' and/or changes in 'how we respond to our environment' must contribute to this rising incidence. In order to gain an improved understanding of the factors influencing the disease process, it is important, firstly, to focus on the organ at the centre of the illness-the pancreas. This review summarises our knowledge of the pathology of the endocrine pancreas in human type 1 diabetes and, in particular, explores the progression of this understanding over the past 25 years.

Myocarditis, hepatitis, and pancreatitis in a patient with coxsackievirus A4 infection: a case report

Viral myocarditis presents with various symptoms, including fatal arrhythmia and cardiogenic shock, and may develop chronic myocarditis and dilated cardiomyopathy in some patients. We report here a case of viral myocarditis with liver dysfunction and pancreatitis. A 63-year-old man was admitted to our hospital with dyspnea. The initial investigation showed pulmonary congestion, complete atrioventricular block, left ventricular dysfunction, elevated serum troponin I, and elevated liver enzyme levels. He developed pancreatitis five days after admission. Further investigation revealed a high antibody titer against coxsackievirus A4. The patient’s left ventricular dysfunction, pancreatitis, and liver dysfunction had resolved by day 14, but his troponin I levels remained high, and an endomyocardial biopsy showed T-lymphocyte infiltration of the myocardium, confirming acute myocarditis. The patient underwent radical low anterior resection five weeks after admission for advanced rectal cancer found incidentally. His serum troponin I and plasma brain natriuretic peptide levels normalized six months after admission. He has now been followed-up for two years, and his left ventricular ejection fraction is stable.

This is the first report of an adult with myocarditis and pancreatitis attributed to coxsackievirus A4. Combined myocarditis and pancreatitis arising from coxsackievirus infection is rare. This patient’s clinical course suggests that changes in his immune response associated with his rectal cancer contributed to the amelioration of his viral myocarditis.

Virus infections in type 1 diabetes

The precise etiology of type 1 diabetes (T1D) is still unknown, but viruses have long been suggested as a potential environmental trigger for the disease. However, despite decades of research, the body of evidence supporting a relationship between viral infections and initiation or acceleration of islet autoimmunity remains largely circumstantial. The most robust association with viruses and T1D involves enterovirus species, of which some strains have the ability to induce or accelerate disease in animal models. Several hypotheses have been formulated to mechanistically explain how viruses may affect islet autoimmunity and β-cell decay. The recent observation that certain viral infections, when encountered at the right time and infectious dose, can prevent autoimmune diabetes illustrates that potential relationships may be more complex than previously thought. Here, we provide a concise summary of data obtained in mouse models and humans, and identify future avenues toward a better characterization of the association between viruses and T1D.

Tropism Analysis of Two Coxsackie B5 Strains Reveals Virus Growth in Human Primary Pancreatic Islets but not in Exocrine Cell Clusters In Vitro

Human Enteroviruses (HEVs) have been implicated in human pancreatic diseases such as pancreatitis and type 1 diabetes (T1D). Human studies are sparse or inconclusive and our aim was to investigate the tropism of two strains of Coxsackie B virus 5 (CBV-5) in vitro to primary human pancreatic cells. Virus replication was measured with TCID50 titrations of aliquots of the culture medium at different time points post inoculation. The presence of virus particles or virus proteins within the pancreatic cells was studied with immunohistochemistry (IHC) and electron microscopy (EM). None of the strains replicated in the human exocrine cell clusters, in contrast, both strains replicated in the endocrine islets of Langerhans. Virus particles were found exclusively in the endocrine cells, often in close association with insulin granules. In conclusion, CBV-5 can replicate in human endocrine cells but not in human exocrine cells, thus they might not be the cause of pancreatitis in humans. The association of virus with insulin granules might reflect the use of these as replication scaffolds.

Pathophysiological mechanisms involving aggressive islet cell destruction in fulminant type 1 diabetes

Fulminant type 1 diabetes is characterized by a rapid onset of severe hyperglycemia and ketoacidosis, with subsequent poor prognosis of diabetic complications. This review summarizes new findings related to the pathophysiology of accelerated β-cell failure in fulminant type 1 diabetes. Immunohistological examination revealed the presence of enterovirus in pancreatic islet cells and exocrine tissues and hyperexpression of pattern recognition receptors (PRRs) including melanoma differentiation-associated antigen 5 (MDA5), retinoic acid-inducible gene-I (RIG-I), Toll-like receptor (TLR)3 and TLR4, essential sensors of innate immunity, in islet cells and mononuclear cells (MNCs) infiltrating islets. Interferon (IFN)-α and IFN-β, products of PRR cascades, were expressed in both islet cells and infiltrating MNCs. Phenotypes of infiltrating cells around and/or into islets were mainly dendritic cells, macrophages and CD8+ T cells. Islet β-cells simultaneously expressed CXC chemokine ligand 10 (CXCL10), IFN-γ and interleukin-18, indicating that these chemokines/ cytotoxic cytokines mutually amplify their cytoplasmic expression in the islet cells. These positive feedback systems might enhance adaptive immunity, leading to rapid and complete loss of β-cells in fulminant type 1 diabetes. In innate and adaptive/autoimmune immune processes, the mechanisms behind bystander activation/killing might further amplify β-cell destruction. In addition to intrinsic pathway of cell apoptosis, the Fas and Fas ligand pathway are also involved as an extrinsic pathway of cell apoptosis. A high prevalence of anti-amylase autoantibodies was recognized in patients with fulminant type 1 diabetes, which suggests that Th2 T-cell reactive immunity against amylase might contribute to β-cell destruction in fulminant type 1 diabetes.

Imaging of β-cell mass and insulitis in insulin-dependent (Type 1) diabetes mellitus

Insulin-dependent (type 1) diabetes mellitus is a metabolic disease with a complex multifactorial etiology and a poorly understood pathogenesis. Genetic and environmental factors cause an autoimmune reaction against pancreatic β-cells, called insulitis, confirmed in pancreatic samples obtained at autopsy. The possibility to noninvasively quantify β-cell mass in vivo would provide important biological insights and facilitate aspects of diagnosis and therapy, including follow-up of islet cell transplantation. Moreover, the availability of a noninvasive tool to quantify the extent and severity of pancreatic insulitis could be useful for understanding the natural history of human insulin-dependent (type 1) diabetes mellitus, to early diagnose children at risk to develop overt diabetes, and to select patients to be treated with immunotherapies aimed at blocking the insulitis and monitoring the efficacy of these therapies. In this review, we outline the imaging techniques currently available for in vivo, noninvasive detection of β-cell mass and insulitis. These imaging techniques include magnetic resonance imaging, ultrasound, computed tomography, bioluminescence and fluorescence imaging, and the nuclear medicine techniques positron emission tomography and single-photon emission computed tomography. Several approaches and radiopharmaceuticals for imaging β-cells and lymphocytic insulitis are reviewed in detail.

Interaction of enterovirus infection and cow's milk-based formula nutrition in type 1 diabetes-associated autoimmunity

BACKGROUND

Enteral virus infections and early introduction of cow's milk (CM)-based formula are among the suggested triggers of type 1 diabetes (T1D)-associated autoimmunity, although studies on their role have remained contradictory. Here, we aimed to analyse whether interactions between these factors might clarify the controversies.

MATERIALS

The study population comprised 107 subjects developing positivity for at least two T1D-associated autoantibodies and 446 control subjects from the Finnish diabetes prediction and prevention cohort. Enterovirus, rotavirus, adenovirus, respiratory syncytial virus and bovine insulin-binding antibodies were analysed from prospective serum samples at 3-24 months of age. Data on infant cow's milk exposure were available for 472 subjects: 251 subjects were exposed to cow's milk before 3 months of age and 221 subjects later in infancy.

RESULTS

Signs of an enterovirus infection by 12 months of age were associated with the appearance of autoimmunity among children who were exposed to cow's milk before 3 months of age. Cox regression analysis revealed a combined effect of enterovirus infection and early cow's milk exposure for the development of ICA and any of the biochemically defined autoantibodies (p = 0.001), of IAA (p = 0.002), GADA (p = 0.001) and IA-2A (p = 0.013).

CONCLUSIONS

The effect of enterovirus infection on the appearance of T1D-associated autoimmunity seems to be modified by exposure to cow's milk in early infancy suggesting an interaction between these factors. Moreover, these results provide an explanation for the controversial findings obtained when analysing the effect of any single one of these factors on the appearance of T1D-associated autoimmunity.

Enterovirus infection and type 1 diabetes mellitus: systematic review and meta-analysis of observational molecular studies

OBJECTIVE

To review the association between current enterovirus infection diagnosed with molecular testing and development of autoimmunity or type 1 diabetes.

DESIGN

Systematic review and meta-analysis of observational studies, analysed with random effects models.

DATA SOURCES

PubMed (until May 2010) and Embase (until May 2010), no language restrictions, studies in humans only; reference lists of identified articles; and contact with authors. Study eligibility criteria Cohort or case-control studies measuring enterovirus RNA or viral protein in blood, stool, or tissue of patients with pre-diabetes and diabetes, with adequate data to calculate an odds ratio and 95% confidence intervals.

RESULTS

The 24 papers and two abstracts (all case-control studies) that met the eligibility criteria included 4448 participants. Study design varied greatly, with a high level of statistical heterogeneity. The two separate outcomes were diabetes related autoimmunity or type 1 diabetes. Meta-analysis showed a significant association between enterovirus infection and type 1 diabetes related autoimmunity (odds ratio 3.7, 95% confidence interval 2.1 to 6.8; heterogeneity χ(2)/df = 1.3) and clinical type 1 diabetes (9.8, 5.5 to 17.4; χ(2)/df = 3.2).

CONCLUSIONS

There is a clinically significant association between enterovirus infection, detected with molecular methods, and autoimmunity/type 1 diabetes. Larger prospective studies would be needed to establish a clear temporal relation between enterovirus infection and the development of autoimmunity and type 1 diabetes.

Type 1 Diabetes: Etiology, Immunology, and Therapeutic Strategies

Type 1 diabetes (T1D) is a chronic autoimmune disease in which destruction or damaging of the beta-cells in the islets of Langerhans results in insulin deficiency and hyperglycemia. We only know for sure that autoimmunity is the predominant effector mechanism of T1D, but may not be its primary cause. T1D precipitates in genetically susceptible individuals, very likely as a result of an environmental trigger. Current genetic data point towards the following genes as susceptibility genes: HLA, insulin, PTPN22, IL2Ra, and CTLA4. Epidemiological and other studies suggest a triggering role for enteroviruses, while other microorganisms might provide protection. Efficacious prevention of T1D will require detection of the earliest events in the process. So far, autoantibodies are most widely used as serum biomarker, but T-cell readouts and metabolome studies might strengthen and bring forward diagnosis. Current preventive clinical trials mostly focus on environmental triggers. Therapeutic trials test the efficacy of antigen-specific and antigen-nonspecific immune interventions, but also include restoration of the affected beta-cell mass by islet transplantation, neogenesis and regeneration, and combinations thereof. In this comprehensive review, we explain the genetic, environmental, and immunological data underlying the prevention and intervention strategies to constrain T1D.

Collecting high-quality pancreatic tissue for experimental study from organ donors with signs of β-cell autoimmunity

BACKGROUND

The aim of this study was to create a new research strategy to obtain high-quality pancreatic tissues from subjects with preclinical or clinical type 1 diabetes, which would open up new avenues for studying the mechanisms of the β-cell damaging process in humans.

RESEARCH DESIGN AND METHODS

A nationwide collaboration network (the PanFin network) was established in Finland to start an on-call screening of diabetes-associated autoantibodies from deceased organ donors and subsequent processing of pancreases from autoantibody-positive donors. This protocol was integrated into the national organ transplantation procedure.

RESULTS

Only a few modifications were needed to the normal transplantation practices. One additional blood sample was obtained from donors for autoantibody analyses, the transplantation team was informed about the autoantibody result and the pancreas of autoantibody-positive donors was transported to the core laboratory. Altogether, 307 donors were screened and 22 (7.2%) were positive for at least one autoantibody and 3 tested positive for two or more autoantibodies out of the five tested (islet cell antibodies, insulin autoantibodies and autoantibodies to glutamic acid decarboxylase, islet antigen 2 and zinc transporter 8). The quality of collected pancreatic tissue was superior to that from autopsies and allowed the detection of both RNA and proteins.

CONCLUSIONS

The study protocol was proven feasible to be carried out on a nationwide scale. It did not interfere with the normal transplantation activities and provided valuable tissue material for research.

The transcription factor MafB antagonizes antiviral responses by blocking recruitment of coactivators to the transcription factor IRF3

Viral infections induce Type I interferons (IFN-α and -β) that recruit unexposed cells in a self-amplifying response. We report that the transcription factor MAFB thwarts auto-amplification by a metastable switch behavior. MAFB acts as a weak positive basal regulator of transcription at the IFN-β promoter through activity at AP-1-like sites. Interferon elicitors recruit the transcription factor IRF3 to the promoter, whereupon MAFB acts as a transcriptional antagonist, impairing the interaction of CREB-binding protein (CBP) with IRF3. Mathematical modeling supports the view that prepositioning of MAFB on the promoter allows the system to respond rapidly to fluctuations in IRF3 activity. Elevated expression of MAFB in human pancreatic islet β-cells might increase cellular vulnerability to viral infections associated with the etiology of type I diabetes.

Enteroviruses, type 1 diabetes and hygiene: a complex relationship

Type 1 diabetes (T1D) is an autoimmune disease in which the immune system mounts an attack on the host's insulin‐producing β cells. Because most cases of T1D cannot be attributed only to individual genetics, it is strongly inferred that there is a significant environmental contribution, such as infection, impacting disease development. The human enteroviruses (HEV) are common picornaviruses often implicated as triggers of human T1D, although precisely which of the numerous HEV may be involved in human T1D development is unknown. Experiments using non‐obese diabetic (NOD) mice, commonly used to model T1D, show that induction of T1D by HEV infection in NOD mice is a multifactorial process involving both the virus and the host. Interestingly, results demonstrate that HEV infection of NOD mice can also induce long‐term protection from T1D under certain conditions, suggesting that a similar mechanism may occur in humans. Based upon both experimental animal and observational human studies, we postulate that HEV have a dual role in T1D development and can either cause or prevent autoimmune disease. Whichever outcome occurs depends upon multiple variables in the host‐virus equation, many of which can be deduced from results obtained from NOD mouse studies. We propose that the background to the sharply rising T1D incidences observed in the 20th century correlates with increased levels of hygiene in human societies. Viewing T1D in this perspective suggests that potential preventative options could be developed. Copyright © 2009 John Wiley & Sons, Ltd.

Enteroviruses in the pathogenesis of type 1 diabetes

The question if enteroviruses could cause beta-cell damage and type 1 diabetes has become more and more relevant when recent studies have provided new evidence supporting this scenario. One important observation is the recent discovery of IFIH1 as a risk gene for type 1 diabetes. This gene is an innate immune system receptor for enteroviruses offering one possible mechanism for the diabetogenic effect of enteroviruses. This is further emphasized by the observations suggesting that the innate immune system is activated in the pancreatic islets of type 1 diabetic patients and that the innate immune system is important for the defense against the virus and for the regulation of adaptive immune system. Important progress has also been gained in studies analyzing pancreas tissue for possible presence of enteroviruses. Several studies have found enteroviruses in the pancreatic islets of type 1 diabetic patients using various methods. The virus seems to be located in the islets while exocrine pancreas is mostly uninfected. One recent study found the virus in the intestinal mucosa in the majority of diabetic patients. Enteroviruses can also infect cultured human pancreatic islets causing either rapid cell destruction or a persistent-like noncytolytic infection. Combined with all previous, epidemiological findings indicating the risk effect of enteroviruses in cross-sectional and prospective studies, these observations fit to a scenario where certain diabetogenic enterovirus variants establish persistent infection in gut mucosa and in the pancreatic islets. This in turn could lead to a local inflammation and the breakdown of tolerance in genetically susceptible individuals. This is also supported by mouse experiments showing that enteroviruses can establish prolonged infection in the pancreas and intestine, and some virus strains cause beta-cell damage and diabetes. In conclusion, recent studies have strengthened the hypothesis that enteroviruses play a role in the pathogenesis of type 1 diabetes. These findings open also new opportunities to explore the underlying mechanism and get closer to causal relationship.

Evaluation of immunohistochemistry and in situ hybridization methods for the detection of enteroviruses using infected cell culture samples

BACKGROUND

Enterovirus infections are frequent in all age groups. In addition to acute infections, they have been connected to chronic diseases such as cardiomyopathies and type 1 diabetes. Based on this there is an increasing need for the reliable detection of enteroviruses in different kinds of tissue samples.

OBJECTIVES

The aim of this study was to set up a test panel which can detect a wide range of different enteroviruses in paraffin-embedded samples and fresh frozen samples using immunohistochemical and in situ hybridization methods.

STUDY DESIGN

A panel of nine enterovirus antibodies was optimized for the detection of different enterovirus types in both paraffin-embedded and frozen cell culture samples. In addition, an oligonucleotide probe detecting all human enteroviruses was evaluated for ISH in formalin-fixed paraffin-embedded cell culture samples.

RESULTS

Most antibodies worked well in both sample types. Some antibodies detected only one of the tested serotypes, whereas others detected several serotypes. ISH was able to detect all tested enterovirus types.

CONCLUSIONS

This test panel makes it possible to detect a wide range of different enterovirus types in both formalin-fixed paraffin-embedded and frozen samples. The same methods can also be applied for tissue sections, but may need further optimization for each tissue type.

Toll-like receptors and type 1 diabetes

Type 1 diabetes (T1D) is an autoimmune disease that results in the progressive loss of insulin producing cells. Studies performed in humans with T1D and animal models of the disease over the past two decades have suggested a key role for the adaptive immune system in disease mechanisms. The role of the innate immune system in triggering T1D was shown only recently. Research in this area was greatly facilitated by the discovery of toll-like receptors (TLRs) that were found to be a key component of the innate immune system that detect microbial infections and initiate antimicrobial host defense responses. New data indicate that in some situations, the innate immune system is associated with mechanisms triggering autoimmune diabetes. In fact, studies preformed in the BioBreeding Diabetes Resistant (BBDR) and LEW1.WR1 rat models of T1D demonstrate that virus infection leads to islet destruction via mechanisms that may involve TLR9-induced innate immune system activation. Data from these studies also show that TLR upregulation can synergize with virus infection to dramatically increase disease penetrance. Reports from murine models of T1D implicate both MyD88-dependent and MyD88-independent pathways in the course of disease. The new knowledge about the role of innate immune pathways in triggering islet destruction could lead to the discovery of new molecules that may be targeted for disease prevention.

Enterovirus infection, CXC chemokine ligand 10 (CXCL10), and CXCR3 circuit: a mechanism of accelerated beta-cell failure in fulminant type 1 diabetes

OBJECTIVE

Fulminant type 1 diabetes is characterized by the rapid onset of severe hyperglycemia and ketoacidosis, with subsequent poor prognosis of diabetes complications. Causative mechanisms for accelerated beta-cell failure are unclear.

RESEARCH DESIGN AND METHODS

Subjects comprised three autopsied patients who died from diabetic ketoacidosis within 2-5 days after onset of fulminant type 1 diabetes. We examined islet cell status, including the presence of enterovirus and chemokine/cytokine/major histocompatibility complex (MHC) expressions in the pancreata using immunohistochemical analyses and RT-PCR.

RESULTS

Immunohistochemical analysis revealed the presence of enterovirus-capsid protein in all three affected pancreata. Extensive infiltration of CXCR3 receptor-bearing T-cells and macrophages into islets was observed. Dendritic cells were stained in and around the islets. Specifically, interferon-gamma and CXC chemokine ligand 10 (CXCL10) were strongly coexpressed in all subtypes of islet cells, including beta-cells and alpha-cells. No CXCL10 was expressed in exocrine pancreas. Serum levels of CXCL10 were increased. Expression of MHC class II and hyperexpression of MHC class I was observed in some islet cells.

CONCLUSIONS

These results strongly suggest the presence of a circuit for the destruction of beta-cells in fulminant type 1 diabetes. Enterovirus infection of the pancreas initiates coexpression of interferon-gamma and CXCL10 in beta-cells. CXCL10 secreted from beta-cells activates and attracts autoreactive T-cells and macrophages to the islets via CXCR3. These infiltrating autoreactive T-cells and macrophages release inflammatory cytokines including interferon-gamma in the islets, not only damaging beta-cells but also accelerating CXCL10 generation in residual beta-cells and thus further activating cell-mediated autoimmunity until all beta-cells have been destroyed.

Histopathology of type 1 diabetes: old paradigms and new insights

Although our knowledge on the various aspects of diabetes development in the NOD mouse model is substantial and keeps expanding at a dramatic pace, the dataset on histopathologic features of type 1 diabetes (T1D) in patients remains largely stagnant. Early work has established an array of common aspects that have become epitomic in the absence of new patient material. There is a growing consensus that an updated and more detailed view is required that challenges and expands our understanding. Comprehensive initiatives are currently ongoing to address these issues in pre-diabetic, recent onset and longstanding type 1 diabetic individuals, and some of the old data have been recently revisited. In this review article, we wish to provide an overview of where we stand today and how we can correlate the various cross-sectional studies from the past with contemporary models of the disease. We believe an enhanced understanding of the many histopathological particularities in patients as compared to animal models will ultimately lead, not only to more fundamental insights, but also to an improved ability to translate pre-clinical data from bench to bedside.

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.

Epidemiology of type 1 diabetes and what animal models teach us about the role of viruses in disease mechanisms

There is a consensus among epidemiologists that the worldwide incidence rate of type 1 diabetes has been rising in recent decades. The cause of this rise is unknown, but epidemiological studies suggest the involvement of environmental factors, and viral infections in particular. Data demonstrating a cause-and-effect relationship between microbial infections and type 1 diabetes and how viruses may cause disease in humans are currently lacking. However, new evidence from animal models supports the hypothesis that viruses induce disease via mechanisms linked with innate immune upregulation. In the BioBreeding Diabetes Resistant rat, infection with a parvovirus induces islet destruction via upregulation of the toll-like receptor 9 (TLR9) signaling pathway. Data from mouse models of diabetes implicate TLR2, TLR3, and TLR7 in the disease process. Understanding the link between environmental agents and innate immune pathways involved in early stages of diabetes may advance the design of immune interventions to prevent disease in genetically susceptible individuals.

Analysis of pancreas tissue in a child positive for islet cell antibodies

AIMS/HYPOTHESIS

Type 1 diabetes is caused by an immune-mediated process, reflected by the appearance of autoantibodies against pancreatic islets in the peripheral circulation. Detection of multiple autoantibodies predicts the development of diabetes, while positivity for a single autoantibody is a poor prognostic marker. The present study assesses whether positivity for a single autoantibody correlates with pathological changes in the pancreas.

METHODS

We studied post mortem pancreatic tissue of a child who repeatedly tested positive for islet cell antibodies (ICA) in serial measurements. Paraffin sections were stained with antibodies specific for insulin, glucagon, somatostatin, interferon alpha, CD3, CD68, cyclooxygenase-2 (COX-2), beta-2-microglobulin, coxsackie B and adenovirus receptor (CAR), natural killer and dendritic cells. Apoptosis was detected using Fas-specific antibody and TUNEL assay. Enterovirus was searched for using immunohistochemistry and in situ hybridisation, as well as enterovirus-specific RT-PCR from serum samples.

RESULTS

The structure of the pancreas did not differ from normal. The number of beta cells was not reduced and no signs of insulitis were observed. Beta-2-microglobulin and CAR were strongly produced in the islets, but not in the exocrine pancreas. Enterovirus protein was detected selectively in the islets by two enterovirus-specific antibodies, but viral RNA was not found.

CONCLUSIONS/INTERPRETATION

These observations suggest that positivity for ICA alone, even when lasting for more than 1 year, is not associated with inflammatory changes in the islets. However, it is most likely that the pancreatic islets were infected by an enterovirus in this child.

Detection of enteroviruses in the intestine of type 1 diabetic patients

Enterovirus infections have been diagnosed more frequently in type 1 diabetic patients than in the healthy population, and enteroviruses have also been found in the pancreas of diabetic patients. Primary replication of the virus occurs in the gut, but there are no previous studies evaluating possible presence of virus in the intestine of diabetic patients. The purpose of this study was to investigate if enteroviruses can be found in small intestinal tissue of type 1 diabetic patients. Formalin-fixed, paraffin-embedded upper intestinal biopsy samples were analysed for the presence of enterovirus using in situ hybridization and immunohistochemistry. Enterovirus was detected by in situ hybridization in six (50%) of the type 1 diabetic patients (n = 12) but in none of the control subjects (n = 10, P = 0.015). Immunohistochemistry identified enterovirus in nine (75%) of the patients and one (10%) control subject (P = 0.004). The presence of the virus was confirmed by reverse transcription-polymerase chain reaction in one of the four patients from whom a frozen and unfixed sample was available. Intestinal morphology was normal in all study subjects. The results suggest that a substantial proportion of type 1 diabetic patients have an ongoing enterovirus infection in gut mucosa, possibly reflecting persistent enterovirus infection. This observation opens new avenues for further studies on the possible role of enteroviruses in human type 1 diabetes.

Group B coxsackievirus diabetogenic phenotype correlates with replication efficiency

Group B coxsackieviruses can initiate rapid onset type 1 diabetes (T1D) in old nonobese diabetic (NOD) mice. Inoculating high doses of poorly pathogenic CVB3/GA per mouse initiated rapid onset T1D. Viral protein was detectable in islets shortly after inoculation in association with beta cells as well as other primary islet cell types. The virulent strain CVB3/28 replicated to higher titers more rapidly than CVB3/GA in the pancreas and in established beta cell cultures. Exchange of 5'-nontranslated regions between the two CVB3 strains demonstrated a variable impact on replication in beta cell cultures and suppression of in vivo replication for both strains. While any CVB strain may be able to induce T1D in prediabetic NOD mice, T1D onset is linked both to the viral replication rate and infectious dose.

Improved crystallization of the coxsackievirus B3 RNA-dependent RNA polymerase

The Picornaviridae virus family contains a large number of human pathogens such as poliovirus, hepatitis A virus and rhinoviruses. Amongst the viruses belonging to the genus Enterovirus, several serotypes of coxsackievirus coexist for which neither vaccine nor therapy is available. Coxsackievirus B3 is involved in the development of acute myocarditis and dilated cardiomyopathy and is thought to be an important cause of sudden death in young adults. Here, the first crystal of a coxsackievirus RNA-dependent RNA polymerase is reported. Standard crystallization methods yielded crystals that were poorly suited to X-ray diffraction studies, with one axis being completely disordered. Crystallization was improved by testing crystallization solutions from commercial screens as additives. This approach yielded crystals that diffracted to 2.1 A resolution and that were suitable for structure determination.

Coxsackievirus infections and NOD mice: relevant models of protection from, and induction of, type 1 diabetes

Human enteroviruses (HEVs) like the group B coxsackieviruses (CVBs) are prime candidates for infectious, environmental causes of human type 1 diabetes (T1D). Non-obese diabetic (NOD) female mice are well protected from T1D onset if inoculated with CVB when young. Older, prediabetic NOD mice can rapidly develop T1D following inoculation with CVB, mimicking clinical reports of disease-associated T1D onset. The ability to induce rapid T1D in NOD mice is linked to the rate of replication of the CVB strain in beta cell cultures and pancreatic tissue, indicating that any CVB strain is potentially diabetogenic under the correct conditions. Rapid T1D onset is preceded by CVB replication in islet cells including beta cells. Although CVB strains do not productively infect healthy islets of young mice, CVBs can replicate in healthy islets in the presence of murine IL-4. These models expand much of what is known or suspected regarding the etiologic role of HEVs in human T1D.

My approach to performing a perinatal or neonatal autopsy

An opportunity to determine the cause of death, factors that may have a role in it, and the extent and cause of malformations is provided by perinatal autopsy. The family may be assisted in finding closure after the death of their infant by the information obtained. Insight into classifying infants appearing normal into one of three groups, small, appropriate and large for gestational age, has been provided, as each group tends to have specific causes of death. In infants with congenital anomalies, patterns of malformation may lead us to the diagnosis. An accurate diagnosis is required to provide counselling for a subsequent pregnancy.

Environmental factors in the development of Type 1 diabetes

Environmental factors appear to play an important role in the pathogenesis of childhood-onset type 1 diabetes (T1D). The most important factors are thought to be infectious, dietary, perinatal, and psychosocial. Enteroviruses (especially Coxsackie B virus), breastfeeding, the early presence or lack of certain foods, birth weight, childhood over-nutrition, maternal islet autoimmunity, and negative stress events have been shown to be related to the prevalence of T1D. However, clear conclusions to date are limited because most studies lacked power to detect exposure/disease associations, were not prospective or long-term, did not start in infancy, had imprecise or infrequent exposure estimates, had confounding exposures, and failed to account for genetic susceptibility. In addition to the identification of specific antigenic triggers, several more general hypotheses, including the accelerator and hygiene hypotheses, are testable approaches worth pursuing.

Bupleurum kaoi inhibits Coxsackie B virus type 1 infection of CCFS-1 cells by induction of type I interferons expression

Coxsackie B virus type 1 (CVB1) infection is known to cause high morbidity and mortality in children, however, there is no effective drug for treating this disease. The present study aimed to examine the antiviral activity of Bupleurum kaoi (BK), a popular herbal drug for treating viral and bacterial infections, against CVB1 infection and its mechanisms of action. Our data showed that BK neutralized the CVB1-induced cytopathic effect in human neonatal foreskin fibroblast cell line (CCFS-1/KMC), with IC50 and EC50 values around 12.38 microg/ml and 50.93 microg/ml, respectively. Its CC50 and SI values were 883.56 microg/ml and 17.34, respectively. These results suggest that BK possessed anti-CVB1 activity, and showed no effect on CCFS-1 cell viability and growth at concentration 250 microg/ml. The time-of-addition studies showed that BK (50, 100 and 200 microg/ml) added at various time of preinfection (-1 to -3 h), coinfection (0 h) and postinfection (1-3 h) could inhibit CVB1 infection. Interestingly, BK also showed an inhibition on viral replication through the induction of IFN-alpha/beta expression. In conclusion, BK possessed antiviral activity against CVB1 infection. It interfered the early stage of viral replication and viral replication after infection through the induction of type I interferon expression.

Lethal enterovirus-induced myocarditis and pancreatitis in a 4-month-old boy

After inconspicuous pregnancy and birth, a 16-year-old mother presented her male baby 5 days later with severe diarrhoea and vomiting. During the following weeks, the child temporarily showed hypotension, hypothermia and increased body temperature, bradyarrythmia with apnoea, continuing diarrhoea, sometimes vomiting and developed signs of pancreatic insufficiency. Due to increasing loss of weight and obviously severe dystrophia, parenteral nutrition had to be initiated. All clinical investigations revealed no underlying disease. Numerous biopsies, mainly from the gastrointestinal tract were taken, but no relevant pathological findings were disclosed. The baby was found lifeless by his mother, 4 months after birth. According to the death certificate, the physicians regarded the lethal outcome as a case of sudden infant death syndrome (SIDS). Histological and immunohistochemical investigations of organ samples revealed signs of myocarditis, pancreatitis and focal pneumonia. Molecularpathological techniques were used to detect enterovirus RNA from tissue samples from the myocardium, liver and pancreas. Enteroviral myocarditis with concomitant pancreatitis was determined as cause of death.

Enteroviruses: new findings on the role of enteroviruses in type 1 diabetes

Common enterovirus infections appear to initiate or facilitate the pathogenetic processes leading to type 1 diabetes, and sometimes also precipitate the clinical disease. It is not known in detail how enterovirus infections bring about the loss of insulin-producing beta-cells, a phenomenon characteristic of the disease. Recent results from studies on pancreases from human autopsies and cultured human islets support the idea that during systemic enterovirus infections, the virus may reach pancreatic islets and cause direct beta-cell damage. Although individual enteroviruses (EV) exhibited differences in their beta-cell tropism in the cultured human islets, all serotypes studied contained highly destructive strains. The final confirmation on the role of enteroviruses in type 1 diabetes can only be obtained from intervention studies. If the association holds true then it would be possible to reduce the risk of developing type 1 diabetes by preventing enterovirus infections with a multivalent enterovirus vaccine that could be given to children soon after birth.

Molecular in situ localization techniques in diagnosis and pathogenicity studies of enteroviral heart disease

BACKGROUND

Enteroviruses, including coxsackieviruses of group B (CVB), are considered to be the most common agents of viral myocarditis. As demonstrated by in situ hybridization for the detection of viral RNA in endomyocardial biopsies and autopsy hearts, such infections are also detectable in patients with 'idiopathic' dilated cardiomyopathy, indicating the possibility of myocardial enterovirus persistence. Persistent enterovirus infection of the human heart is supported by the recent discovery in various murine models of chronic myocarditis, demonstrating that CVB3, typically a cytolytic virus, is capable of evading immunological surveillance in a host-dependent manner.

METHODS

In order to investigate mechanisms underlying acute and persistent enterovirus infection in the myocardium, diverse tissues from CVB3 infected immunocompetent mice were processed in in situ hybridization for the detection of viral RNA. In addition, virus-host interactions were analyzed at the subcellular level in the myocardium in the course of the infection by means of an electron microscopic in situ hybridization assay.

RESULTS

A close spatial and temporal relationship between viral replication and inflammatory lesions was observed during the acute as well as persistent phase of myocardial infection. A multiorgan study revealed that, in addition to heart muscle cells, lymphoid cells of spleen and lymph nodes are persistently infected. The results obtained at the ultrastructural level demonstrate that loss of host cell integrity is a direct consequence of acute viral replication and confirm that chronic myocarditis may be associated with persistent heart muscle infection.

CONCLUSIONS

Viral replication plays a central role in the pathogenesis of acute and chronic myocarditis. Immune cells are important targets of the infection and provide a non-cardiac viral reservoir.

Coxsackievirus B3 infection and type 1 diabetes development in NOD mice: insulitis determines susceptibility of pancreatic islets to virus infection

Group B coxsackieviruses (CVB) are believed to trigger some cases of human type 1 diabetes (T1D), although the mechanism by which this may occur has not been shown. We demonstrated previously that inoculation of young nonobese diabetic (NOD) mice with any of several different CVB strains reduced T1D incidence. We also observed no evidence of CVB replication within islets of young NOD mice, suggesting no role for CVB in T1D induction in the NOD mouse model. The failure to observe CVB replication within islets of young NOD mice has been proposed to be due to interferon expression by insulin-producing beta cells or lack of expression of the CVB receptor CAR. We found that CAR protein is detectable within islets of young and older NOD mice and that a CVB3 strain, which expresses murine IL-4, can replicate in islets. Mice inoculated with the IL-4 expressing CVB3 chimeric strain were better protected from T1D onset than were mock-infected control mice despite intraislet viral replication. Having demonstrated that CVB can replicate in healthy islets of young NOD mice when the intraislet environment is suitably altered, we asked whether islets in old prediabetic mice were resistant to CVB infection. Unlike young mice in which insulitis is not yet apparent, older NOD mice demonstrate severe insulitis in all islets. Inoculating older prediabetic mice with different pathogenic CVB strains caused accelerated T1D onset relative to control mice, a phenomenon that was preceded by detection of virus within islets. Together, the results suggest a model for resolving conflicting data regarding the role of CVB in human T1D etiology.