Impaired Ca2+ response to glucose in mouse β-cells infected with Coxsackie B or Echo virus
ABSTRACT Five strains of Coxsackie B4 virus and one of Echo 11 virus were tested with regard to their ability to replicate in pancreatic mouse beta-cells and interfere with the alterations of the cytoplasmic Ca2+ concentration ([Ca2+]i) induced by glucose. All strains except one both multiplied and caused cytopathic effect. In a control group 68% of the beta-cells responded to 11 mM glucose with large amplitude oscillations of [Ca2+]i. After inoculation with the infectious strains these oscillations appeared in only 5% of the beta-cells, whereas the non-infectious strain did not modify the glucose effect on [Ca2+]i. Despite the virus interference with the glucose response, [Ca2+]i was increased after depolarization with excessive extracellular K+ and the oscillations were induced in most beta-cells when glucose was combined with the insulin-releasing sulfonylurea tolbutamide.
- SourceAvailable from: Malin Flodstrom-Tullberg
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- "Infections with the coxsackievirus serotype B4 (CB4) have been etiologically linked to type 1 diabetes in humans , and CB4 was isolated from patients who died shortly after being diagnosed with the disease (Szopa et al., 1993). Several CB4 isolates can infect human and murine pancreatic ␤-cells and cause cellular dysfunction and/or death in vitro (Frisk et al., 1994; Roivainen et al., 2000; Szopa et al., 1986, 1990; Yoon et al., 1979). Moreover , some clinical isolates, after several passages through mouse pancreatic ␤-cell cultures, fulfilled Koch's postulate by inducing a diabetes-like syndrome in susceptible strains of mice (Toniolo et al., 1982; Yoon et al., 1978). "
ABSTRACT: Coxsackieviral infections have been linked etiologically to multiple diseases. The serotype CB4 is associated with acute pancreatitis and autoimmune type 1 diabetes. To delineate the mechanisms of host survival after an acute infection with CB4 (strain E2), we have investigated the role of nitric oxide (NO), generated by the inducible form of nitric oxide synthase (NOS2), in viral clearance and pancreatic β-cell maintenance. Mice deficient in NOS2 (NOS2−/− mice) and their wild-type (wt) counterparts were injected with CB4, after which both groups developed severe pancreatitis, hepatitis, and hypoglycemia within 3 days. Within 4 to 7 days postinfection (p.i.), most of the NOS2−/− mice died and at a strikingly higher mortality rate than wt mice. Histological examination of pancreata from both infected NOS2−/− and infected wt mice revealed early and complete destruction of the pancreatic acinar tissue, but intact, insulin-stained islets. When examined up to 8 weeks p.i., neither surviving NOS2−/− mice nor surviving wt mice developed hyperglycemia. However, the clearance of infectious CB4 was different between the mice. The spleens of NOS2−/− survivors were cleared of infectious virus with kinetics similar to that of wt mice, but the livers, pancreata, kidneys, and hearts of the NOS2−/− groups cleared virus more slowly than those of the wt group. This delayed clearance was particularly prominent in the livers of infected NOS2−/− mice, which also showed prolonged histopathological features of viral hepatitis. Taken together, this outcome suggests that NOS2 (and NO) is not required for the prevention of pancreatic β-cell depletion after CB4 infection. Instead the critical actions of NOS2 apparently occur early in the host immune response, allowing mice to survive and clear virus. Moreover, the data support the existence of an organ-specific dependency on NO for a rapid clearance of CB4.Virology 04/2001; 281(2-281):205-215. DOI:10.1006/viro.2000.0801 · 3.28 Impact Factor
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ABSTRACT: The mechanisms that regulate susceptibility to virus-induced autoimmunity remain undefined. We establish here a fundamental link between the responsiveness of target pancreatic beta cells to interferons (IFNs) and prevention of coxsackievirus B4 (CVB4)-induced diabetes. We found that an intact beta cell response to IFNs was critical in preventing disease in infected hosts. The antiviral defense, raised by beta cells in response to IFNs, resulted in a reduced permissiveness to infection and subsequent natural killer (NK) cell-dependent death. These results show that beta cell defenses are critical for beta cell survival during CVB4 infection and suggest an important role for IFNs in preserving NK cell tolerance to beta cells during viral infection. Thus, alterations in target cell defenses can critically influence susceptibility to disease.Nature Immunology 05/2002; 3(4):373-82. DOI:10.1038/ni771 · 24.97 Impact Factor
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ABSTRACT: We have studied the occurrence of enterovirus (EV)-RNA at the onset of childhood type 1 diabetes in all 24 new cases of childhood type 1 diabetes during 1 year in Uppsala county, Sweden. We also studied 24 matched control subjects and 20 siblings of the patients. RNA was isolated from peripheral blood mononuclear cells and EV-RNA detected by RT-PCR. Primers (groups A and B) corresponding to conserved regions in the 5' noncoding region (NCR) of EV were used in the PCRs, and the amplicons were sequenced. By the use of group A primers, EV-RNA was found in 12 (50%) of the 24 type 1 diabetic children, 5 (26%) of 19 siblings, and none of the control subjects. Both patients and siblings showed a higher frequency of EV-RNA compared with the control subjects. The group B primers detected EV-RNA in all three groups but did not show statistically significant differences between the groups. The EV-RNA positivity with the group B primers was 11 (46%) of 24 in the type 1 diabetic children, 11 (58%) of 19 in the siblings, and 7 (29%) of 24 in the control subjects. The significant difference between groups seen with the group A primers but not with the group B primers might indicate the existence of diabetogenic EV strains. The phylogenetic analysis of the PCR products revealed clustering of the sequences from patients and siblings into five major branches when the group A PCR primers were used. With the group B primers, the sequences from patients, siblings, and control subjects formed three major branches in the phylogenetic tree, where 6 of the 7 control subjects clustered together in a sub-branch of CBV-4/VD2921. Seven of the type 1 diabetic children clustered together in another sub-branch of CBV-4/VD2921. Five of the type 1 diabetic children formed a branch together with the CBV-4/E2 strain, four clustered together with CBV-5, and one formed a branch with echovirus serotype. The presence of EV-RNA in the blood cells of most newly diagnosed type 1 diabetic children supports the hypothesis that a viral infection acts as an exogenous factor. In addition, sequencing of the PCR amplicons from the type 1 diabetic children, their siblings, and matched control subjects might reveal differences related to diabetogenic properties of such a virus.Diabetes 07/2002; 51(6):1964-71. DOI:10.2337/diabetes.51.6.1964 · 8.47 Impact Factor