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Studies of Enterovirus Infection and Induction of Innate Immunity in Human Pancreatic Cells
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Clinical Immunology.
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Several epidemiological and clinical studies have indicated a possible role of Enterovirus (EV) infection in type 1 diabetes (T1D) development. However, the exact casual mechanism of these viruses in T1D development is not known. The aim of this thesis is to study various EVs that have been shown to differ in their immune phenotype, lytic ability, association with induction of islet autoantibodies, ability to replicate, cause islet disintegration and induce innate antiviral pathways in infected pancreatic cells in vitro. Furthermore, EV presence and pathogenic process in pancreatic tissue and isolated islets of T1D patients was also studied.

Studies in this thesis for first time show the detection of EV RNA and protein in recent onset live T1D patients supporting the EV hypothesis in T1D development. Further all EV serotypes studied were able to replicate in islets, causing variable amount of islet disintegration ranging from extensive islet disintegration to not affecting islet morphology at all. However, one of the EV serotype replicated in only two out of seven donors infected, highlighting the importance of individual variation between donors. Further, this serotype impaired the insulin response to glucose stimulation without causing any visible islet disintegration, suggesting that this serotype might impaired the insulin response by inducing a functional block. Infection of human islets with the EV serotypes that are differentially associated with the development of islet autoantibodies showed the islet cell disintegration that is comparable with their degree of islet autoantibody seroconversion. Suggesting that the extent of the epidemic-associated islet autoantibody induction may depend on the ability of the viral serotypes to damage islet cells. Furthermore, one of the EV strains showed unique ability to infect and replicate both in endo and exocrine cells of the pancreas. EV replication in both endo and exocrine cells affected the genes involved in innate and antiviral pathways and induction of certain genes with important antiviral activity significantly varied between different donors. Suggesting that the same EV infection could result in different outcome in different individuals. Finally, we compared the results obtained by lytic and non lytic EV strains in vitro with the findings reported in fulminant and slowly progressing autoimmune T1D and found some similarities. In conclusion the results presented in this thesis further support the role of EV in T1D development and provide more insights regarding viral and host variation.  This will improve our understanding of the possible causative mechanism by EV in T1D development.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2016. , 63 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 1223
Keyword [en]
Type 1 Diabetes, Enterovirus, Innate Immunity, Pancreas
National Category
Microbiology in the medical area
Identifiers
URN: urn:nbn:se:uu:diva-284370ISBN: 978-91-554-9572-5 (print)OAI: oai:DiVA.org:uu-284370DiVA: diva2:920231
Public defence
2016-06-07, Rudbecklaboratoriet, Dag Hammarskjölds väg 20, 752 37 Uppsala, Uppsala, 09:00 (English)
Opponent
Supervisors
Available from: 2016-05-13 Created: 2016-04-18 Last updated: 2016-06-01
List of papers
1. Detection of a low-grade enteroviral infection in the islets of Langerhans of living patients newly diagnosed with type 1 diabetes
Open this publication in new window or tab >>Detection of a low-grade enteroviral infection in the islets of Langerhans of living patients newly diagnosed with type 1 diabetes
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2015 (English)In: Diabetes, ISSN 0012-1797, E-ISSN 1939-327X, Vol. 64, no 5, 1682-1687 p.Article in journal (Refereed) Published
Abstract [en]

The Diabetes Virus Detection study (DiViD) is the first to examine fresh pancreatic tissue at the diagnosis of type 1 diabetes for the presence of viruses. Minimal pancreatic tail resection was performed 3-9 weeks after onset of type 1 diabetes in 6 adult patients (age 24-35 years). The presence of enteroviral capsid protein 1 (VP1) and the expression of class I HLA were investigated by immunohistochemistry. Enterovirus RNA was analyzed from isolated pancreatic islets and from fresh frozen whole pancreatic tissue using PCR and sequencing. Non-diabetic organ donors served as controls. VP1 was detected in the islets of all type 1 diabetes patients (2 of 9 controls). Hyperexpression of class I HLA molecules was found in the islets of all patients (1 of 9 controls). Enterovirus specific RNA sequences were detected in 4 of 6 cases (0 of 6 controls). The results were confirmed in different laboratories. Only 1.7 % of the islets contained VP1 positive cells and the amount of enterovirus RNA was low. The results provides evidence for the presence of enterovirus in pancreatic islets of type 1 diabetic patients, being consistent with the possibility that a low grade enteroviral infection in the pancreatic islets contribute to disease progression in humans.

National Category
Endocrinology and Diabetes Microbiology
Identifiers
urn:nbn:se:uu:diva-239513 (URN)10.2337/db14-1370 (DOI)000353431200023 ()25422108 (PubMedID)
Available from: 2014-12-29 Created: 2014-12-29 Last updated: 2017-12-05
2. Infection of Human Islets of Langerhans With Two Strains of Coxsackie B Virus Serotype 1: Assessment of Virus Replication, Degree of Cell Death and Induction of Genes Involved in the Innate Immunity Pathway
Open this publication in new window or tab >>Infection of Human Islets of Langerhans With Two Strains of Coxsackie B Virus Serotype 1: Assessment of Virus Replication, Degree of Cell Death and Induction of Genes Involved in the Innate Immunity Pathway
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2014 (English)In: Journal of Medical Virology, ISSN 0146-6615, E-ISSN 1096-9071, Vol. 86, no 8, 1402-1411 p.Article in journal (Refereed) Published
Abstract [en]

Type 1 diabetes mellitus is believed to be triggered, in part, by one or more environmental factors and human enteroviruses (HEVs) are among the candidates. Therefore, this study has examined whether two strains of HEV may differentially affect the induction of genes involved in pathways leading to the synthesis of islet hormones, chemokines and cytokines in isolated, highly purified, human islets. Isolated, purified human pancreatic islets were infected with strains of Coxsackievirus B1. Viral replication and the degree of CPE/islet dissociation were monitored. The expression of insulin, glucagon, CXCL10, TLR3, IF1H1, CCL5, OAS-1, IFN beta, and DDX58 was analyzed. Both strains replicated in islets but only one of strain caused rapid islet dissociation/CPE. Expression of the insulin gene was reduced during infection of islets with either viral strain but the gene encoding glucagon was unaffected. All genes analyzed which are involved in viral sensing and the development of innate immunity were induced by Coxsackie B viruses, with the notable exception of TLR3. There was no qualitative difference in the expression pattern between each strain but the magnitude of the response varied between donors. The lack of virus induced expression of TLR3, together with the differential regulation of IF1H1, OAS1 and IFN beta, (each of which has polymorphic variants influence the predisposition to type 1 diabetes), that might result in defective clearance of virus from islet cells. The reduced expression of the insulin gene and the unaffected expression of the gene encoding glucagon by Coxsackie B1 infection is consistent with the preferential beta-cell tropism of the virus.

Keyword
enterovirus, type 1 diabetes, innate immunity, human pancreatic islets, RNA sensors
National Category
Infectious Medicine Microbiology
Identifiers
urn:nbn:se:uu:diva-231113 (URN)10.1002/jmv.23835 (DOI)000339486200015 ()24249667 (PubMedID)
Available from: 2014-09-05 Created: 2014-09-04 Last updated: 2017-12-05
3. Expression of Innate Immunity Genes and Damage of Primary Human Pancreatic Islets by Epidemic Strains of Echovirus: Implication for Post-Virus Islet Autoimmunity
Open this publication in new window or tab >>Expression of Innate Immunity Genes and Damage of Primary Human Pancreatic Islets by Epidemic Strains of Echovirus: Implication for Post-Virus Islet Autoimmunity
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2013 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, no 11, e77850- p.Article in journal (Refereed) Published
Abstract [en]

Three large-scale Echovirus (E) epidemics (E4, E16, E30), each differently associated to the acute development of diabetes related autoantibodies, have been documented in Cuba. The prevalence of islet cell autoantibodies was moderate during the E4 epidemic but high in the E16 and E30 epidemic. The aim of this study was to evaluate the effect of epidemic strains of echovirus on beta-cell lysis, beta-cell function and innate immunity gene expression in primary human pancreatic islets. Human islets from non-diabetic donors (n = 7) were infected with the virus strains E4, E16 and E30, all isolated from patients with aseptic meningitis who seroconverted to islet cell antibody positivity. Viral replication, degree of cytolysis, insulin release in response to high glucose as well as mRNA expression of innate immunity genes (IFN-b, RANTES, RIG-I, MDA5, TLR3 and OAS) were measured. The strains of E16 and E30 did replicate well in all islets examined, resulting in marked cytotoxic effects. E4 did not cause any effects on cell lysis, however it was able to replicate in 2 out of 7 islet donors. Beta-cell function was hampered in all infected islets (P<0.05); however the effect of E16 and E30 on insulin secretion appeared to be higher than the strain of E4. TLR3 and IFN-beta mRNA expression increased significantly following infection with E16 and E30 (P<0.033 and P<0.039 respectively). In contrast, the expression of none of the innate immunity genes studied was altered in E4-infected islets. These findings suggest that the extent of the epidemic-associated islet autoimmunity may depend on the ability of the viral strains to damage islet cells and induce pro-inflammatory innate immune responses within the infected islets.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:uu:diva-212334 (URN)10.1371/journal.pone.0077850 (DOI)000326499300010 ()
Available from: 2013-12-10 Created: 2013-12-09 Last updated: 2017-12-06Bibliographically approved
4. Field strains of Echovirus 6 infect human endocrine and exocrine pancreatic cells and induce pro-inflammatory innate immune responses.
Open this publication in new window or tab >>Field strains of Echovirus 6 infect human endocrine and exocrine pancreatic cells and induce pro-inflammatory innate immune responses.
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(English)Article in journal (Refereed) In press
Abstract [en]

Increasing evidence suggests that type 1 diabetes (T1D) is a combined endocrine-exocrine disease. Human enteroviruses (HEV) have been suggested to induce T1D, but so far evidence on HEV infection in human pancreas has been reported only in islets and ductal cells. Aim of this study was to investigate the capability of HEV strains to infect primary human endocrine and exocrine pancreatic cells and to induce the expression of innate immunity genes in both cell types. Isolated human pancreatic islets and exocrine cells were either mock-infected or inoculated with seven field isolates of Echovirus 6 (E6). Beta-cell tropic strains of E4, E16 and E30 were assayed in primary exocrine cells. Viral infection, replication, virus-induced cytopathic effect (CPE) and expression of innate immunity genes were measured. All the seven strains of E6 replicated in both pancreatic endocrine and exocrine cells with infectious progeny production and appearance of CPE. By contrast, no virus titer increase or CPE were observed in exocrine cells exposed to E4, E16 and E30. Virus particles were found in E6-infected acinar cells, both free in cytoplasm and enclosed in vacuoles. Insulin granules accumulation in proximity to virus particles and beta cells functional impairment were demonstrated in E6-infected islets. Endocrine and exocrine cells responded to E6 infection by upregulating the transcription of genes involved in viral recognition (IF1H1), antiviral defense (OAS1, IFN-β) and inflammation (CXCL10, CCL5). Our results indicate that islets and exocrine pancreatic cells productively support the E6 infection and suggest that HEV-associated T1D may involve both endocrine and exocrine pancreas.

National Category
Clinical Medicine Microbiology
Identifiers
urn:nbn:se:uu:diva-283276 (URN)
Available from: 2016-04-12 Created: 2016-04-12 Last updated: 2016-06-01
5. Gene expression analysis of human islets in a subject at onset of type 1 diabetes
Open this publication in new window or tab >>Gene expression analysis of human islets in a subject at onset of type 1 diabetes
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2014 (English)In: Acta Diabetologica, ISSN 0940-5429, E-ISSN 1432-5233, Vol. 51, no 2, 199-204 p.Article in journal (Refereed) Published
Abstract [en]

Swollen islet cells have been repeatedly described at onset of type 1 diabetes, but the underlying mechanism of this observation, termed hydropic degeneration, awaits characterization. In this study, laser capture microdissection was applied to extract the islets from an organ donor that died at onset of type 1 diabetes and from an organ donor without pancreatic disease. Morphologic analysis revealed extensive hydropic degeneration in 73 % of the islets from the donor with type 1 diabetes. Expression levels of genes involved in apoptosis, ER stress, beta cell function, and inflammation were analyzed in isolated and laser-captured islets by qPCR. The chemokine MCP-1 was expressed in islets from the donor with type 1 diabetes while undetectable in the control donor. No other signs of inflammation were detected. There were no signs of apoptosis on the gene expression level, which was also confirmed by negative immunostaining for cleaved caspase-8. There was an increased expression of the transcription factor ATF4, involved in transcription of ER stress genes, in the diabetic islets, but no further signs of ER stress were identified. In summary, on the transcription level, islets at onset of type 1 diabetes in which many beta cells display hydropic degeneration show no obvious signs of apoptosis, ER stress, or inflammation, supporting the notion that these cells are responding normally to high glucose and eventually succumbing to beta cell exhaustion. Also, this study validates the feasibility of performing qPCR analysis of RNA extracted from islets from subjects with recent onset of T1D and healthy controls by laser capture microdissection.

National Category
Endocrinology and Diabetes
Identifiers
urn:nbn:se:uu:diva-202844 (URN)10.1007/s00592-013-0479-5 (DOI)000334054200004 ()23624551 (PubMedID)
Available from: 2013-06-28 Created: 2013-06-28 Last updated: 2017-12-06Bibliographically approved
6. Enterovirus-induced changes in explanted human islet of Langerhans resemble findings in islets of fulminant and conventional type 1 diabetes
Open this publication in new window or tab >>Enterovirus-induced changes in explanted human islet of Langerhans resemble findings in islets of fulminant and conventional type 1 diabetes
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Hypothesis: Fulminant Type 1 diabetes is a unique subtype of T1D, mostly reported in the Japanese population, which is characterized by extensive beta cell death already at onset, often without any insulitis. Enterovirus (EV) infections are associated with the etiology of both fulminant and conventional T1D. However the causative mechanism is not known for any of these diseases. EVs capability to cause lytic vs non-lytic infection in explanted human islets may have implications on the pathogenesis of these two types of T1D.

Aim: To study the effect of infection of explanted human pancreatic islets with lytic (CBV-1) and non-lytic (CBV-4) Coxsackie B virus strains on cytopathic effect/islet disintegration and to what extent genes involved in viral sensing, antiviral defense and encoding of islet auto-antigens are affected by the viral replication. Also, to compare these findings with the findings reported in fulminant and conventional T1D.

Methods: Degree of cytopathic effect/islet disintegration was studied and viral replication was measured. Genes involved in viral sensing (NOD2, TLR7 and TLR4), antiviral pathways (OAS2, MX1, PKR, and IRF7), genes coding for known islet auto antigens (GAD65, ZNT8) and the islet hormones, insulin and glucagon, were studied. Mock-infected explanted islet served as controls.

Results: All CBV strains replicated in the explanted islets but only the CBV-1 strains caused cytopathic effect/islet cell disintegration. Infection with all CBV strains resulted in the induction of genes encoding OAS2 and MX1. In contrast, mRNA expression levels of the gene encoding insulin was reduced. The gene encoding PKR was induced by one of the lytic strains (CBV-1-11) and also by the non-lytic CBV4 strain, while the mRNA expression levels of genes encoding glucagon, NOD2, TLR7, TLR4, MCL1, GAD65 and ZNT8 were not significantly affected.

National Category
Endocrinology and Diabetes Microbiology
Identifiers
urn:nbn:se:uu:diva-283281 (URN)
Available from: 2016-04-12 Created: 2016-04-12 Last updated: 2016-06-01

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