ANIMAL MODEL OF HUMAN DISEASE
Diabetes Mellitus (Juvenile- and MaturityOstTps
OstTps
Animal Model: Mice Infected with the M Variant of Encephalomyocarditis Virus
Contributed by: John E. Craighead, MD, Department of Pathology, University of Vermont College of Medicine, Burlington, VT 05401. Biologic Features
The M variant of EMC virus induces diabetes mellitus in several strains of adult mice.1-5 Incompletely defined polygenic influences appear to affect the occurrence of the disease. The incidence in DBA/2 animals is >70%, whereas it is about 40% in those of the CD-1 strain. Fewer than 10% of mice of the C3H, C57B1, BALB/CJ and A/J strains are affected.5'6 Although animals of both sexes can be infected with EMC virus, the incidence of diabetes in males is substantially greater than in females.2'57 Its development in castrated male and female animals is markedly enhanced by the administration of testosterone.7 Glucocorticoid hormones also increase the severity of the disease in intact mice.8 Overt hyperglycemia develops 4 to 7 days after subcutaneous inoculation of virus. It is associated with hypoinsulinemia and the presence of decreased amounts of insulin in the pancreatic tissue (Figure 1). Hyperglycemia often is transient, although many mice exhibit abnormal glucose tolerance during convalescence. Persistently elevated fasting concentrations of blood glucose (150 to >500 mg/100 ml) are noted in a variable proportion. While the metabolic abnormality appears to improve with time, some animals loose weight despite hyperphagia and die. Early in the infection, beta cells are degranulated and a variable number undergo necrosis (Figure 2). At this time substantial amounts of virus are found in the pancreatic tissue. During the acute stages of the infection viral antigen is located in the beta cells by immunofluorescence.5 Alpha cells exhibit few if any abnormalities.9 An infiltrate of macrophages and lymphocytes is present in and around the islets during the second week after virus inoculation 2,4 (Figure 3). Publication sponsored by the Registry of Comparative Pathology of the Armed Forces Institute of Pathology and supported by Public Health Service Grant RR 00301 from the Division of Research Resources, US Department of Health, Education and Welfare, under the auspices of Universities Associated for Research and Education in Pathology, Inc.
American Journal of Pathology
CRAIGHEAD
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Fig 1-Blood glucose (open circles) and pancreatic immunologically reactive insulin circoncentrations (closed male cles) in 12-week-old, CD-1 mice at intervals after inoculation of EMC virus (Reproduced by permission of S. Karger).
9
DAYS AFTER INOCULATION
Fig 2-Ultrastructural features o: pancreatic beta cells in 12week-old, male DBA-2 mice 4 (A) and 6 days (B) after the inoculation of EMC virus. Note the intracellular edema early in the course of the infection (A) and degranulation of beta cells later (B) (Uranyl acetate). (Reproduced by permission of American Journal of Pathology). Mononuclear cell infilFig 3 trate adjacent to islet of Langerhan in a 12-week-old, male CD-1 mouse 8 days after inoculation of EMC virus (H&E).
Vol. 78, No. 3 March 1975
ANIMAL MODEL OF DIABETES MELLITUS
539
Subsequently, a spectrum of lesions is observed. In frankly hyperglycemic mice the beta cells are degranulated and decreased in number whereas in less severely affected animals the islets often appear normal by light microscopy. Ultrastructural studies reveal evidence of beta cell regeneration in chronically hyperglycemic mice'0 (Figure 4). Metaplasia of acinar elements to a beta cell morphology also is observed. Comparison with Human Disease
Biochemically the disease in EMV-virus-infected mice strikingly resembles juvenile-type diabetes in man."'3 The hyperglycemia is abrupt in onset and associated with marked hypoinsulinemia. Although "remissions" occur in some animals, abnormalities of glucose tolerance or hyperglycemia persist into convalescence. Pathologically the islets are degranulated and frequently exhibit the mononuclear cell infiltrates (insulitis) characteristic of the condition in man.14 Moreover, during the chronic stages of the disease the insular tissue in the pancreas is decreased and the beta cells show cytologic abnormalities. Similar lesions have been observed in children dying with diabetic ketoacidosis. It is likely that subtle degrees of damage to the islets could result in a maturity-onset syndrome at times of metabolic stress. Some workers
Fig 4-Islets of Langerhan in hyperglycemic (>300 mg/100 ml), 1-year-old male mice which were infected at 3 months of age with EMC virus. Note the disorganization and the variation in cell size in the islet in A. Evidence of metaplasia of acinar cells is seen (arrow). Note the degranulation of beta cells in B (Aldehyde-fuchsin).
540
CRAIGHEAD
American Journal of Pathology
have suggested that virus-induced beta cell damage could sensitize the host and result in an immunologically mediated lesion of the islets.15 These possibilities have not been fully explored as of yet. References
1. Craighead JE: Pathogenicity of the M and E variants of the encephalomyocarditis (EMC) virus. I. Myocardiotropic and neurotropic properties. Am J Pathol 48:333-345, 1966 2. Craighead JE, Steinke J: Diabetes mellitus-like syndrome in mice infected with encephalomyocarditis virus. Am J Pathol 63: 119-130, 1971 3. Muntefering H: Zur Pathologie des Diabetes Mellitus der weissen Maus bei der EMC-Virusinfektion: histologische, electronenmikroskopische und quantitativ morphologische Befunde an den Langerhansschen Inseln. Virchows Arch [Pathol Anat] 356:207-234, 1972 4. Wellmann KF, Amsterdam D, Brancato P, Volk BW: Fine structure of pancreatic islets of mice infected with the M variant of the encephalomyocarditis virus. Diabetologia 8:349-357, 1972 5. Boucher DW, Notkins AL: Virus-induced diabetes mellitus. I. Hyperglycemia and hypoinsulinemia in mice infected Nvith encephalomyocarditis virus. J Exp Med 137:1226-1239, 1973 6. Craighead JE, Higgins DA: Genetic influences affecting the occurrence of a diabetes mellitus-like disease in mice infected with the encephalomyocarditis virus. J Exp Med 139:414-426, 1974 7. Freedman A, Craighead JE: Influence of sex hormones on EMC virus induced diabetes mellitus. (Unpublished data) 8. Craighead JE: Pathogenicity of the M and E variants of the encephalomyocarditis (EMC) virus. II. Lesions of the pancreas, parotid and lacrimal glands. Am J Pathol 48:375-386, 1966 9. Craighead JE, Kanich RE, Kessler JB: Lesions of the islets of Langerhans in encephalomyocarditis virus-infected mice with diabetes mellitus-like disease. I. Acute lesions. Am j Pathol 74:287-300, 1974 10. Craighead JE, Kessler JB: Lesions of the islets of Langerhans in encephalomyocarditis virus-infected mice with diabetes mellitus-like disease. II. Chronic lesions. (Unpublished data) 11. Craighead JE: Workshop on viral infection and diabetes mellitus in man. J Infect Dis 125:568-570, 1972 12. Craighead JE: Inflammatory lesions of the islets of Langerhans. Handbook of Physiology, Section 7, Endocrinology, Vol 1. Edited by RO Greep, EB Astwood. Baltimore, Williams and Wilkins, 1972, pp 315-321 13. Craighead JE: Insulitis associated with viral infection. Immunity and Autoimmunity in Diabetes Mellitus. Edited by PA Bastenie. Amsterdam, Excerpta Medica, 1973 14. Gepts W: Pathologic anatomy of the pancreas in juvenile diabetes mellitus. Diabetes 14:619-633, 1965 15. Bastenie PA: Immunity, autoimmunity and diabetes. Diabetes. Edited by WJ Malaisse, J Pirart, Amsterdam, Excerpta Medica, 1973
Diabetes Mellitus (Juvenile- and MaturityOstTps
OstTps
Animal Model: Mice Infected with the M Variant of Encephalomyocarditis Virus
Contributed by: John E. Craighead, MD, Department of Pathology, University of Vermont College of Medicine, Burlington, VT 05401. Biologic Features
The M variant of EMC virus induces diabetes mellitus in several strains of adult mice.1-5 Incompletely defined polygenic influences appear to affect the occurrence of the disease. The incidence in DBA/2 animals is >70%, whereas it is about 40% in those of the CD-1 strain. Fewer than 10% of mice of the C3H, C57B1, BALB/CJ and A/J strains are affected.5'6 Although animals of both sexes can be infected with EMC virus, the incidence of diabetes in males is substantially greater than in females.2'57 Its development in castrated male and female animals is markedly enhanced by the administration of testosterone.7 Glucocorticoid hormones also increase the severity of the disease in intact mice.8 Overt hyperglycemia develops 4 to 7 days after subcutaneous inoculation of virus. It is associated with hypoinsulinemia and the presence of decreased amounts of insulin in the pancreatic tissue (Figure 1). Hyperglycemia often is transient, although many mice exhibit abnormal glucose tolerance during convalescence. Persistently elevated fasting concentrations of blood glucose (150 to >500 mg/100 ml) are noted in a variable proportion. While the metabolic abnormality appears to improve with time, some animals loose weight despite hyperphagia and die. Early in the infection, beta cells are degranulated and a variable number undergo necrosis (Figure 2). At this time substantial amounts of virus are found in the pancreatic tissue. During the acute stages of the infection viral antigen is located in the beta cells by immunofluorescence.5 Alpha cells exhibit few if any abnormalities.9 An infiltrate of macrophages and lymphocytes is present in and around the islets during the second week after virus inoculation 2,4 (Figure 3). Publication sponsored by the Registry of Comparative Pathology of the Armed Forces Institute of Pathology and supported by Public Health Service Grant RR 00301 from the Division of Research Resources, US Department of Health, Education and Welfare, under the auspices of Universities Associated for Research and Education in Pathology, Inc.
American Journal of Pathology
CRAIGHEAD
538
500
400
200
I
- I50 J n
0
o
{.
I
E
200
100 [I
100
I
50
I
I
5
7
0
0 0
X 30000D
3
,
Fig 1-Blood glucose (open circles) and pancreatic immunologically reactive insulin circoncentrations (closed male cles) in 12-week-old, CD-1 mice at intervals after inoculation of EMC virus (Reproduced by permission of S. Karger).
9
DAYS AFTER INOCULATION
Fig 2-Ultrastructural features o: pancreatic beta cells in 12week-old, male DBA-2 mice 4 (A) and 6 days (B) after the inoculation of EMC virus. Note the intracellular edema early in the course of the infection (A) and degranulation of beta cells later (B) (Uranyl acetate). (Reproduced by permission of American Journal of Pathology). Mononuclear cell infilFig 3 trate adjacent to islet of Langerhan in a 12-week-old, male CD-1 mouse 8 days after inoculation of EMC virus (H&E).
Vol. 78, No. 3 March 1975
ANIMAL MODEL OF DIABETES MELLITUS
539
Subsequently, a spectrum of lesions is observed. In frankly hyperglycemic mice the beta cells are degranulated and decreased in number whereas in less severely affected animals the islets often appear normal by light microscopy. Ultrastructural studies reveal evidence of beta cell regeneration in chronically hyperglycemic mice'0 (Figure 4). Metaplasia of acinar elements to a beta cell morphology also is observed. Comparison with Human Disease
Biochemically the disease in EMV-virus-infected mice strikingly resembles juvenile-type diabetes in man."'3 The hyperglycemia is abrupt in onset and associated with marked hypoinsulinemia. Although "remissions" occur in some animals, abnormalities of glucose tolerance or hyperglycemia persist into convalescence. Pathologically the islets are degranulated and frequently exhibit the mononuclear cell infiltrates (insulitis) characteristic of the condition in man.14 Moreover, during the chronic stages of the disease the insular tissue in the pancreas is decreased and the beta cells show cytologic abnormalities. Similar lesions have been observed in children dying with diabetic ketoacidosis. It is likely that subtle degrees of damage to the islets could result in a maturity-onset syndrome at times of metabolic stress. Some workers
Fig 4-Islets of Langerhan in hyperglycemic (>300 mg/100 ml), 1-year-old male mice which were infected at 3 months of age with EMC virus. Note the disorganization and the variation in cell size in the islet in A. Evidence of metaplasia of acinar cells is seen (arrow). Note the degranulation of beta cells in B (Aldehyde-fuchsin).
540
CRAIGHEAD
American Journal of Pathology
have suggested that virus-induced beta cell damage could sensitize the host and result in an immunologically mediated lesion of the islets.15 These possibilities have not been fully explored as of yet. References
1. Craighead JE: Pathogenicity of the M and E variants of the encephalomyocarditis (EMC) virus. I. Myocardiotropic and neurotropic properties. Am J Pathol 48:333-345, 1966 2. Craighead JE, Steinke J: Diabetes mellitus-like syndrome in mice infected with encephalomyocarditis virus. Am J Pathol 63: 119-130, 1971 3. Muntefering H: Zur Pathologie des Diabetes Mellitus der weissen Maus bei der EMC-Virusinfektion: histologische, electronenmikroskopische und quantitativ morphologische Befunde an den Langerhansschen Inseln. Virchows Arch [Pathol Anat] 356:207-234, 1972 4. Wellmann KF, Amsterdam D, Brancato P, Volk BW: Fine structure of pancreatic islets of mice infected with the M variant of the encephalomyocarditis virus. Diabetologia 8:349-357, 1972 5. Boucher DW, Notkins AL: Virus-induced diabetes mellitus. I. Hyperglycemia and hypoinsulinemia in mice infected Nvith encephalomyocarditis virus. J Exp Med 137:1226-1239, 1973 6. Craighead JE, Higgins DA: Genetic influences affecting the occurrence of a diabetes mellitus-like disease in mice infected with the encephalomyocarditis virus. J Exp Med 139:414-426, 1974 7. Freedman A, Craighead JE: Influence of sex hormones on EMC virus induced diabetes mellitus. (Unpublished data) 8. Craighead JE: Pathogenicity of the M and E variants of the encephalomyocarditis (EMC) virus. II. Lesions of the pancreas, parotid and lacrimal glands. Am J Pathol 48:375-386, 1966 9. Craighead JE, Kanich RE, Kessler JB: Lesions of the islets of Langerhans in encephalomyocarditis virus-infected mice with diabetes mellitus-like disease. I. Acute lesions. Am j Pathol 74:287-300, 1974 10. Craighead JE, Kessler JB: Lesions of the islets of Langerhans in encephalomyocarditis virus-infected mice with diabetes mellitus-like disease. II. Chronic lesions. (Unpublished data) 11. Craighead JE: Workshop on viral infection and diabetes mellitus in man. J Infect Dis 125:568-570, 1972 12. Craighead JE: Inflammatory lesions of the islets of Langerhans. Handbook of Physiology, Section 7, Endocrinology, Vol 1. Edited by RO Greep, EB Astwood. Baltimore, Williams and Wilkins, 1972, pp 315-321 13. Craighead JE: Insulitis associated with viral infection. Immunity and Autoimmunity in Diabetes Mellitus. Edited by PA Bastenie. Amsterdam, Excerpta Medica, 1973 14. Gepts W: Pathologic anatomy of the pancreas in juvenile diabetes mellitus. Diabetes 14:619-633, 1965 15. Bastenie PA: Immunity, autoimmunity and diabetes. Diabetes. Edited by WJ Malaisse, J Pirart, Amsterdam, Excerpta Medica, 1973
