Diabetes-like Syndrome Research Articles

Complete Nucleotide Sequence of a Coxsackievirus B4 Strain that Establishes Infection in ICR Mice Pancreas and Induces Glucose Intolerance

Some coxsackievirus B serotypes are potentially diabetogenic. Previous studies revealed that the virulence and the tissue damage varied with the genetics of the virus strain as well as with the genetics of the mice. A single amino acid variation can alter virulence and tropism in both murine and in vitro models. However, the genetic determinants of this phenomenon have not been determined. In this study, infections with a laboratory strain of coxsackievirus B4 resulted in a diabetes-like syndrome in ICR mice, characterized by chronic pancreatic inflammation together with dysregulation in glucose metabolism, loss of pancreatic acinar tissue and persistent infection in islets. To characterize the genetic determinants involved in the mouse pancreas adaptation, the laboratory strain of coxsackievirus B4 was cloned for molecular characterization. Comparing the whole genome sequence of this virus strain with the other coxsackievirus B4 strains revealed some differences. Altogether 15 nucleotides were changed, resulting in 10 amino acid substitutions, which might be responsible for the pathogenic phenotype of this strain in mice.

Phenotypic and genetic changes in coxsackievirus B5 following repeated passage in mouse pancreas in vivo

Common enterovirus infections appear to initiate or facilitate the pathogenetic processes leading to type 1 diabetes, and also sometimes precipitate the clinical disease. In experimental infection of mice, coxsackieviruses have shown to have a strong affinity for the exocrine tissue, while even in lethal cases, the islets remain unaffected. The virus strain most intensively studied in this respect is the diabetogenic variant E2 of coxsackievirus B4. In addition, it is known that all six serotypes of coxsackie B viruses can be made diabetogenic by repeated passages in either mouse pancreas in vivo or in cultured mouse beta-cells in vitro. However, the genetic determinants of the phenomenon have not been determined. In the present study, a laboratory strain of coxsackievirus B5 was passaged repeatedly in mouse pancreas in vivo. After 15 passages, the virus phenotype was clearly changed and infection of the variant resulted in a diabetes-like syndrome in mice characterized by chronic pancreatic inflammation together with dysregulation in glucose metabolism, loss of pancreatic acinar tissue, and mild insulitis. In order to characterize the genetic determinants involved in mouse pancreas adaptation, the passaged virus variant together with the parental virus strain was cloned for molecular characterization. The whole genome sequencing of both virus strains revealed only limited differences. Altogether, eight nucleotides were changed resulting in five amino acid substitutions, of which three were located in the capsid proteins.

Interferon-gamma plays a role in pancreatic islet-cell destruction of reovirus type 2-induced diabetes-like syndrome in DBA/1 suckling mice.

Reovirus type 2 (Reo-2) infection in DBA/1 suckling mice causes insulitis, which leads to pancreatic islet-cell destruction, resulting in a diabetes-like syndrome. T-helper (Th) 1 cytokines are thought to play a key role in islet inflammation in insulin-dependent diabetes mellitus. We examined this hypothesis in the Reo-2-induced diabetes-like syndrome. We used reverse transcriptase polymerase chain reaction (PCR) and quantitative PCR techniques to examine mRNA expression of interferon (IFN)-gamma (Th1 type cytokine), and interleukin (IL)-4 (Th2 type cytokine) in splenic cells. We observed that in Reo-2 infected mice the level of IFN-gamma expression increases with the development of insulitis, whereas expression of message for IL-4 is minimal to detectable with the immuno-inflammatory process 10 days after infection. The treatment of monoclonal antibody (mAb) against mouse IFN-gamma during the expansion phase of insulitis (5-9 days after infection) inhibited the development of insulitis and the elevation of blood glucose concentrations in a dose dependent manner. Furthermore altered CD4+/CD8+ cell ratio compared with uninfected mice in the splenic cells by the infection was recovered to the ratio of uninfected mice by the treatment of mAb against mouse IFN-gamma, suggesting normalization of T cell balance in immune system. These results suggest that Reo-2-triggered autoimmune insulitis may be mediated by Th1 lymphocytes and IFN-gamma may play a role in islet inflammation leading to islet cell destruction.

Dimethylthiourea reduces pancreatic islet-cell damage in DBA/1 sucking mice with reovirus type-2 infection

Reovirus type 2 (Reo-2) infection in DBA/1 sucking mice causes pancreatic islet-cell destruction, which results in a diabetes-like syndrome. To investigate the role of reactive oxygen species (ROS), the protective effect of dimethylthiourea (DMTU) was examined, this substance being an effective scavenger of hydroxyl radicals. The degree of cellular infiltration in and around pancreatic islets was the same in mice receiving either virus only or virus and DMTU. The latter had no effect on (1) the number or type of white blood cells, (2) lymphocyte function-associated antigen 1-alpha-positive splenocytes, or (3) viral multiplication in the pancreas. However, treatment with DMTU inhibited the elevation of blood glucose concentrations and reduced pancreatic islet-cell damage (beta-cell degranulation and necrosis). These results suggest that ROS play a role in the pathogenesis of Reo-2-induced diabetes-like syndrome.

Analysis of sequence and pathogenic properties of two variants of encephalomyocarditis virus differing in a single amino acid in VP1

The encephalomyocarditis (EMC) virus-induced diabetes-like syndrome in mouse inbred strains was used as a model to study the insulin-dependent diabetes mellitus (IDDM). Our investigations were performed with two EMC virus variants, PV2 and PV7. After infection of SJL mice with 10 5 PFU of PV2 about 70% of the animals developed a diabetes-like syndrome, whereas the PV7 infected mice appeared healthy. Histological examination and in situ experiments revealed that the islets of Langerhans are a main target of PV2, whereas PV7 infection leads to only modest changes of the islets. Sequence analysis of both variants revealed one amino acid exchange within the capsid protein VP1. Hence, we describe the first diabetogenic and non-diabetogenic EMCV variants differing in only one single amino acid.

Complete nucleotide sequence of a strain of coxsackie B4 virus of human origin that induces diabetes in mice and its comparison with nondiabetogenic coxsackie B4 JBV strain

The E2 strain of coxsackie B4 virus (CB4), which is of human origin, can induce a diabetes-like syndrome in mice. The cDNA of the genome of the E2 strain was cloned and sequenced. The E2 viral genome was found to comprise 7,396 bases, which appear to encode a polyprotein of 2,183 amino acids with an overall similarity of 94.91% to nondiabetogenic CB4 prototype JBV strain. The E2 genome is organized like other enteroviruses. It has a 5' noncoding region of 744 nucleotides, a single long open translational reading frame starting at nucleotide 745 and extending to nucleotide 7293, a 3' noncoding region of 100 nucleotides, and a poly (A) tract. Genomic sequence comparison of the E2 and JBV strains showed 1,369 nucleotide substitutions in the genome of the E2 strain, most of which are single and silent. There were 111 resultant amino acid changes arising from some of these substitutions, including 82 amino acid changes in the noncapsid proteins, and 29 amino acid changes in the capsid proteins VP1, VP2, VP3, and VP4, which showed 11, 13, 4, and 1 substitution(s), respectively. Noncapsid protein P2-C showed eight amino acid substitutions. On the basis of the sequence comparison of E2 and JBV strains of CB4, we suggest that some of the amino acid changes in the capsid and noncapsid proteins of the E2 strain may be involved in the determination of its diabetogenicity.

Reovirus type 2-induced diabetes in mice prevented by immunosuppression and thymic hormone

Reovirus type 2 that had been isolated from a cow with diarrhoea and passaged in bovine kidney cell culture produced a Type 1 (insulin-dependent) diabetes-like syndrome when inoculated into NC mice. The infection resulted in insulitis and destruction of islet cells. Viral antigens were found in islet cells by staining with fluorescein-labelled antibody to reovirus type 2. The destruction of islet cells resulted in abnormalities shown on glucose tolerance testing. Studies on the susceptibility of the host showed that only certain strains of mice had overtly abnormal glucose tolerance tests when infected with reovirus type 2. To assess the immunological role in the pathogenesis of reovirus type 2-induced diabetes, infected mice were subjected to immunosuppressive or thymic hormone treatment. The administration of either anti-thymocyte serum or serum thymic factor reduced or prevented the development of the diabetes-like syndrome, while Arg-Lys-Asp-Val-Try did not show any therapeutic effects.

Comparative acute toxicity of chlorocitrate and fluorocitrate in dogs

The high-dose effects of chlorocitrate [(−)- threo-chlorocitric acid] were compared in vivo to another halogenated citrate analog, and a well-known inhibitor of the tricarboxylic acid (TCA) cycle, fluorocitrate. The compounds were given iv to two dogs per sex per group, and a control group received an equimolar amount of citric acid. Chlorocitrate (100 mg/kg) showed TCA cycle inhibition as did fluorocitrate (8 mg/kg) in that both caused depletion of ATP and accumulation of citrate in the liver. Chlorocitrate was a significantly weaker inhibitor of citrate metabolism than fluorocitrate as evidenced by a substantially lower accumulation of serum citrate despite a much higher dose. Both halocitrates produced a similar diabetes-like syndrome (hyperglycemia, glycosuria) mediated by a significant hyperglucagonemia and slight hypoinsulinemia. Chlorocitrate was more potent in this effect and a much greater buildup of plasma lactate ensued (18- versus 3.7-fold increase), enough to explain lethality observed in earlier studies. In contrast, fluorocitrate produced a severe life-threatening hypocalcemia (−30%), and hypercalcuria was observed. This effect on calcium distribution was only minimal with chlorocitrate. Both halocitrates had a similar depressive effect on circulation as evidenced by hypothermia, bradycardia, and elongation of the QT-interval. These changes were considered to be the result of lactic acidosis and the ongoing ion imbalance since heart ATP levels were not depleted.

Perspectives on the role of viruses in insulin-dependent diabetes.

Insulin-dependent diabetes mellitus (IDDM) results from the destruction of pancreatic beta cells. Viruses have been suggested as one of the possible causes. The evidence for viruses comes largely from experiments in animals, but several studies in humans also point to viruses as a trigger of this disease in some cases. Encephalomyocarditis (EMC) virus, Mengovirus (2T), and Coxsackie B4 virus infect and destroy pancreatic beta cells when inoculated into mice. This results in hypoinsulinemia and hyperglycemia. The development of EMC virus-induced diabetes is dependent on the genetic background of the host and genetic makeup of the virus. Animals with diabetes for several months show some long-term complications, including glomerulosclerosis, ocular changes, and decreased bone formation and mineralization in addition to acute metabolic changes. EMC virus-induced diabetes can be prevented by a live-attenuated vaccine. The capacity of Coxsackie B4 virus to induce diabetes is also influenced by the genetic background of the host. However, Mengovirus-induced diabetes is not dependent on the genetic background of the host. In contrast to the EMC, Mengo, and Coxsackie B4 viruses, reovirus type 1 seems to be somehow associated with an autoimmune response producing a diabetes-like syndrome in suckling mice. This virus produces an autoimmune polyendocrinopathy that results in very mild and transient glucose intolerance. Several common human viruses including mumps, Coxsackie B3 and B4 viruses, and reovirus type 3 can infect human beta cells in culture and destroy them. A variant of Coxsackie B4 virus has been isolated from the pancreas of a child who died of acute-onset IDDM.(ABSTRACT TRUNCATED AT 250 WORDS)

Encephalomyocarditis virus and diabetes mellitus: studies on virus mutants in susceptible and non-susceptible mice.

The so-called M-variant (especially subtype D) of encephalomyocarditis virus (EMCV) induces a diabetes-like syndrome in certain mouse strains which may serve as a model of insulin-dependent diabetes mellitus (IDDM) in man. The development and course of diabetes was influenced by a number of virus and host factors, among these being virus strain, virus dose, mouse strain, age, sex, and the host's immunological status. In a D-variant stock of EMCV, we found a virus plaque variant (PV 2) diabetogenic for DBA/2 mice, and at least one variant (PV 7) that did not affect carbohydrate metabolism. Although the diabetogenicity of PV 2 proved to be a genetically stable characteristic after further passages in vivo and in vitro, the incidence of diabetes varied somewhat (mean value 65% in 10-week-old DBA/2 mice infected with 10(5) p.f.u.). Both lower (10(1) or 10(3) p.f.u.) and higher (10(7) or 10(8) p.f.u.) virus doses led to a diminished incidence and severity of diabetes. In younger animals (5 weeks) transient hyperglycaemia often appeared, whereas in older animals (20 weeks) there was a higher rate of mortality. Histological examination of the islets of Langerhans in diabetes-susceptible (DBA/2) and resistant (C57BL/6) mice revealed that EMCV-induced hyperglycaemia appeared to develop in parallel to islet cell damage. Even in diabetic animals, some unaffected islets were regularly found. This study demonstrates that EMCV mutants may have completely different biological effects and produce diabetes only in special circumstances. Host factors play a significant role in the development of diabetes.

Development of a Diabetes-Like Syndrome in an Athymic Nude Balb/c Mouse Colony

Development of a Diabetes-Like Syndrome in an Athymic Nude Balb/c Mouse Colony

Nonhuman primates as models for the study of human diabetes mellitus.

Nonhuman primates have been used for a variety of studies on diabetes mellitus. Spontaneous, natural forms of diabetes have been well documented in several species; there are limited data on numerous other species that indicate diabetes or a diabetes-like syndrome. The causes and manifestations of spontaneous diabetes, their prevalence, and their severity vary among species. Diabetes has also been induced in nonhuman primates with streptozotocin, alloxan, hypothalamic lesions, or pancreatectomy. The extent and severity of metabolic and hormonal abnormalities vary according to the method of induction, the individual monkey, and the species. Metabolic, hormonal, and pathologic abnormalities present in human diabetics also occur in monkeys with either spontaneous or induced diabetes. Hyperglycemia and impaired glucose clearance are common, lipid concentrations are elevated, and hemoglobin A1c concentrations are increased in hyperglycemic monkeys. Monkeys may have fasting hypo- or hyperinsulinemia; insulin responses are often impaired in glucose tolerance tests. Glucagon concentrations may be increased. Aortic atherosclerosis, muscle capillary microangiopathies, cataracts, and glomerulosclerosis have been documented. Primate size and longevity allow longitudinal studies with procedures that may not be feasible in smaller animals or in human beings. Nonhuman primates may be the models of choice for studies on selected aspects of diabetes and its secondary complications.

Virus-induced diabetes mellitus. XV. Beta cell damage and insulin-dependent hyperglycemia in mice infected with coxsackie virus B4.

Coxsackie virus B4 that had been passaged in cultures enriched for pancreatic beta cells produced a diabetes-like syndrome when inoculated into SJL/J mice. The infection resulted in insulitis and destruction of beta cells. Viral antigens were found in beta cells by staining with fluorescein-labeled antibody to Coxsackie virus B4. The destruction of beta cells led to a decrease in the immunoreactive insulin content of the pancreas and hypoinsulinemia. The reduction in immunoreactive insulin correlated inversely with the elevation of glucose in the blood and over 80% of the animals were found to be hyperglycemic within 14 days after infection. The percentage of animals with hyperglycemia decreased with time and at the end of 60 days, less than 5% of the animals were still hyperglycemic. However, many of the normoglycemic mice were found to be metabolically abnormal when evaluated by glucose tolerance tests. Studies on the susceptibility of the host showed that only certain inbred strains of mice became diabetic when infected with Coxsackie virus B4. It is concluded that both the passage history of the virus and the strain of the host influence the development of diabetes.

Evidence for a single locus controlling susceptibility to virus-induced diabetes mellitus

THE M-variant of encephalomyocarditis virus (EMC) attacks pancreatic β cells and produces a diabetes-like syndrome in certain inbred strains of mice1,2. Studies based on crosses between strains of mice that develop diabetes (susceptible) and strains of mice that do not develop diabetes (resistant) showed that susceptibility to EMC-induced diabetes is inherited as an autosomal recessive trait3–5. Although earlier experiments based on F2 data had suggested that more than one genetic locus might be involved, lack of backcross data, wide variation between experiments, and the influence of non-genetic factors on glucose levels precluded more precise genetic analysis5. The present investigation was initiated to study in greater depth the mode of inheritance of EMC-induced diabetes. The data presented here on susceptible and resistant parental strains and the F1 and backcross offspring are consistent with a mendelian mode of inheritance, principally controlled by a single locus, involving two or more alleles.

Infection of human pancreatic beta cell cultures with mumps virus

THE development of a diabetes-like syndrome in virus-infected animals, particularly in certain strains of mice infected with the M-variant of encephalomyocarditis (EMC) virus has recently been demonstrated1,2. The possibility that viruses might also cause diabetes mellitus in humans, particularly in juveniles, has been suggested periodically since the turn of the century1–6. The evidence, however, is largely circumstantial and comes from case reports showing a temporal relationship between the onset of certain viral infections, particularly mumps, and the subsequent development of diabetes. Although it has been known for some time that pancreatitis may be a complication of mumps7–10, specific involvement of the beta cells has never been demonstrated. Since it is not feasible to obtain pancreatic biopsies during the course of viral infections, we initiated experiments to determine if human pancreatic beta cells grown in culture were susceptible to mumps virus. We have used a double-label antibody technique, using fluorescein labelled anti-mumps antibody and rhodamine labelled anti-insulin antibody, and we show here for the first time that human beta cells can be infected with mumps virus.

Laboratory animals exhibiting obesity and diabetes syndromes

Spontaneous hyperglycemia, hyperinsulinemia and obesity are common features for at least one period of the life-time in some strains of mice. Both genetic and environmental factors are involved in the pathogenesis of the diabetes-like syndrome, making these strains excellent models for studies on both obesity and diabetes-like states. The metabolic peculiarities can be due to a dominant gene, as for the yellow obese, or a single recessive gene, as in the obese and the diabetes mouse; or they can be of polygenic origin, as for the KK and the NZO mouse. However, the severity of the metabolic disorder is due to the interaction of the mutant genes with modifiers in the background genome, rather than being exclusively the manifestation of the mutant genes themselves. Studies on the pathophysiology and biochemistry of these animals have revealed interstrain differences, different patterns of development of the metabolic disorder, and different degrees of severity of the diabetes-like syndrome. Although the primary causes of the syndrome remain unclear in some strains, an involvement of hypothalamic feeding centers has been implicated.

Virus-induced diabetes mellitus. I. Hyperglycemia and hypoinsulinemia in mice infected with encephalomyocarditis virus.

Infection of DBA/2N male mice with encephalomyocarditis virus resulted in a diabeteslike syndrome characterized by hyperglycemia, glycosuria, hypoinsulinemia, polydipsia, and polyphagia. Blood glucose levels were elevated within 4 days after infection and reached a maximum mean level of 320 mg/100 ml within 12 days. Approximately 60-80% of the animals developed a transient hyperglycemia while 10-15% of the animals remained hyperglycemic for well over 6 mo. The remaining animals failed to become hyperglycemic but many had abnormal glucose tolerance curves. Hyperglycemia was most pronounced when animals were allowed free access to food, and the incidence of byperglycemia was related both to the strain and sex of the animals, with few females developing hyperglycemia. The amount of immunoreactive insulin in the plasma of infected hyperglycemic mice was significantly lower than in appropriate controls, and injection of exogenous insulin resulted in a rapid drop in the blood glucose levels. Despite the fact that certain animals were hyperglycemic for many months, virus could not be recovered from the pancreas after the first 10 days of the infection.

The influence of genetic background on expression of mutations at the diabetes locus in the mouse. I. C57BL-KsJ and C57BL-6J strains.

Two new diabetic strains, C57BL/KsJ-db 2J and C57BL/6J-db 2J, have been developed. C57BL/KsJ-db 2J/db2J mice are indistinguishable from C57BL/KsJ-db/db mice, the original diabetes mutation. Both have severe diabetes characterized by hyperphagia, obesity, marked hyperglycemia, temporarily elevated plasma insulin concentrations, and typical degenerative changes in the islets of Langerhans. In contrast, C57BL/6J-db 2J/db2J mice, although also hyperphagic and obese, have mild diabetes characterized by transitory hyperglycemia and markedly elevated plasma insulin concentrations coupled with marked hypertrophy of the islets and increased proliferative capacity of beta cells. The mild diabetes-like syndrome produced by diabetes-2J on the C57BL/6J background is similar to that produced by the obese gene (ob) on the same background. The islet responses, whether atrophy or hypertrophy, appear to be due to the interaction of diabetes-2J (and possibly obese) with modifiers in the genetic background rather than being peculiar to the specific mutant. The markedly different disease patterns that result when the same gene is placed on different inbred backgrounds emphasize the importance of strict genetic control in biochemical and physiological studies with these and other obesity mutants.