Akihisa Imagawa

A NOVEL SUBTYPE OF TYPE 1 DIABETES MELLITUS CHARACTERIZED BY A RAPID ONSET AND AN ABSENCE OF DIABETES-RELATED ANTIBODIES

BACKGROUND AND METHODS Type 1 diabetes mellitus is now classified as autoimmune (type 1A) or idiopathic (type 1B), but little is known about the latter. We classified 56 consecutive Japanese adults with type 1 diabetes according to the presence or absence of glutamic acid decarboxylase antibodies (their presence is a marker of autoimmunity) and compared their clinical, serologic, and pathological characteristics. RESULTS We divided the patients into three groups: 36 patients with positive tests for serum glutamic acid decarboxylase autoantibodies, 9 with negative tests for serum glutamic acid decarboxylase antibodies and glycosylated hemoglobin values higher than 11.5 percent, and 11 with negative tests for serum glutamic acid decarboxylase antibodies and glycosylated hemoglobin values lower than 8.5 percent. In comparison with the first two groups, the third group had a shorter mean duration of symptoms of hyperglycemia (4.0 days), a higher mean plasma glucose concentration (773 mg per deciliter [43 mmol per liter]) in spite of lower glycosylated hemoglobin values, diminished urinary excretion of C peptide, a more severe metabolic disorder (with ketoacidosis), higher serum pancreatic enzyme concentrations, and an absence of islet-cell, IA-2, and insulin antibodies. Immunohistologic studies of pancreatic-biopsy specimens from three patients with negative tests for glutamic acid decarboxylase autoantibodies and low glycosylated hemoglobin values revealed T-lymphocyte-predominant infiltrates in the exocrine pancreas but no insulitis and no evidence of acute or chronic pancreatitis. CONCLUSIONS Some patients with idiopathic type 1 diabetes have a nonautoimmune, fulminant disorder characterized by the absence of insulitis and of diabetes-related antibodies, a remarkably abrupt onset, and high serum pancreatic enzyme concentrations.

Mononuclear cell infiltration and its relation to the expression of major histocompatibility complex antigens and adhesion molecules in pancreas biopsy specimens from newly diagnosed insulin-dependent diabetes mellitus patients.

We examined pancreas biopsy specimens from 18 newly diagnosed insulin-dependent diabetes mellitus (IDDM) patients to elucidate the mechanism underlying beta cell destruction. Pancreas islets were seen in all patients and insulitis in eight patients. Infiltrating mononuclear cells consisted of CD4+T, CD8+T, B lymphocytes, and macrophages. Among them, CD8+T lymphocytes were predominant and macrophages followed. The expression of MHC class I antigens was increased in islet and endothelial cells in nine patients. MHC class II expression was increased in endothelial cells of the same patients. The expression of intercellular adhesion molecule-1 was increased in endothelial cells in two of the nine patients with MHC hyperexpression; in one of them, lymphocyte function-associated antigen-3 expression was also increased. Out of the eight patients with insulitis, seven showed MHC class I hyper-expression, whereas 2 of the 10 patients without insulitis showed the phenomenon (P < 0.05). The relation between insulitis and the hyperexpression of adhesion molecules was not evident. In conclusion, we revealed the close relation between CD8+T lymphocyte-predominant insulitis and MHC class I hyperexpression in islet cells. This suggests that infiltrating CD8+T lymphocytes recognize islet autoantigens in association with increased MHC class I molecules and act as major effector cells in autoimmune response against islet cells in IDDM pancreases. The role of adhesion molecules in the pathogenesis of IDDM still remains to be elucidated.

Fas and Fas ligand expression in inflamed islets in pancreas sections of patients with recent-onset Type I diabetes mellitus.

Aims/hypothesis. Type I (insulin-dependent) diabetes results mainly from T-cell-mediated autoimmune destruction of pancreatic beta cells. Cytotoxic T lymphocytes destroy target cells via a perforin-based or Fas-based mechanism. Our previous study indicated that the Fas-Fas ligand (FasL) pathway is required for the development of autoimmune diabetes in the NOD mouse. We now investigated whether or not the Fas-FasL system is involved in the beta-cell destruction in human Type I diabetes. Methods. We immunohistochemically analysed pancreas biopsy specimens of 13 recent-onset patients. Results. Pancreatic islets were identified but showed various degrees of reduction in beta-cell volume in all patients. Out of 13 patients 6 had insulitis. In these 6 patients Fas was expressed in both the islets and infiltrating cells but not in either cell type in the 7 other patients without insulitis. Double immunostaining showed that Fas was positive in 92.2 to 97.7 % of beta cells but only in 17.6 to 46.7 % of alpha cells in Fas-positive, insulin-remaining islets. We found FasL was expressed exclusively in islet-infiltrating cells in patients with insulitis. Double immunostaining revealed that the most prevalent phenotype of FasL-positive cells was CD8, which was followed by macrophages and CD4. Conclusion/interpretation. The interaction between Fas on beta cells and FasL on infiltrating cells might trigger selective apoptotic beta-cell death in inflamed islets, leading to immune-mediated Type I diabetes. [Diabetologia (1999) 42: 1332–1340]

Fulminant type 1 diabetes: a novel clinical entity requiring special attention by all medical practitioners

Fulminant type 1 diabetes is a recently discovered subtype of type 1 diabetes. It is defined as diabetes in which the process of β-cell destruction and the progression of hyperglycemia and ketoacidosis are extremely rapid. The pathogenesis of this disease remains to be clarified, but the involvement of both genetic background—especially human leukocyte antigen genes—and viruses has been suggested. Fulminant type 1 diabetes has the following clinical characteristics: duration of hyperglycemic symptoms is 4 days on average; there is a high prevalence of preceding common-cold-like and gastrointestinal symptoms; there is a near-normal level of glycated hemoglobin in spite of very high plasma glucose levels associated with ketoacidosis; the disease is sometimes related to pregnancy; and there are increased serum pancreatic enzyme levels, absent C-peptide levels, but virtually no detectable autoantibodies against constituents of pancreatic β cells. The presence of the above characteristics strongly indicates the diagnosis of fulminant type 1 diabetes. Once the diagnosis of this disease is suspected, treatment of diabetic ketoacidosis must be started immediately, as in all other cases of type 1 diabetes. Otherwise, the death of the patient is likely to occur within 24 h. All medical practitioners must remember that this extremely rapidly progressing type of diabetes does exist, and they must pay special attention not to overlook it.

Different contribution of class II HLA in fulminant and typical autoimmune type 1 diabetes mellitus

Aims/hypothesisFulminant type 1 diabetes, which is characterised by a markedly acute onset of diabetes and an absence of islet-related autoantibodies, accounts for 20% of type 1 diabetes in Japan. We aimed to clarify the contribution of the HLA subtype to fulminant type 1 diabetes in Japanese.MethodsWe determined the serological subtypes of HLA-A, -DR and -DQ in 115 patients with fulminant type 1 diabetes, 98 patients with typical type 1A diabetes and 190 normal control subjects.ResultsThe frequency of HLA-DR4, but not DR9, was significantly higher in fulminant type 1 diabetes, while those of HLA-DR1, DR2, DR5 and DR8 were significantly lower than those in controls. In contrast, DR9 but not DR4 was more frequent and DR2 was extremely rare in typical type 1A diabetes. Haplotype analysis revealed that DR4-DQ4 was significantly more frequent, and both DR2-DQ1 and DR8-DQ1 were less frequent in fulminant diabetes. In type 1A diabetes, DR2-DQ1 was extremely rare while DR9-DQ3 was significantly more frequent. In the combination analysis, the homozygotes of DR4-DQ4 in fulminant type 1 diabetes and DR9-DQ3 in typical type 1A diabetes indicated high odds ratios (13.3 and 13.3, respectively).Conclusions/interpretationOur results suggest that class II HLA contributes to the development of fulminant type 1 diabetes. Susceptibility and resistance of the HLA subtype to type 1 diabetes are distinct between fulminant and typical autoimmune type 1 diabetes.

Macrophages and dendritic cells infiltrating islets with or without beta cells produce tumour necrosis factor-α in patients with recent-onset type 1 diabetes

Aims/hypothesisType 1A diabetes results from autoimmune destruction of pancreatic beta cells. We examined the involvement of TNF-α and IL-1β, as well as of T cells, macrophages and dendritic cells, in the destruction of beta cells in patients with recent-onset type 1 diabetes.Materials and methodsWe obtained pancreatic biopsy specimens from six patients with recent-onset type 1 diabetes and analysed these by immunohistochemistry.ResultsT cell infiltration was less common in islets without beta cells (12.5 [0–33.3]%) than in those with beta cells (46.0 [17.4–83.3]%), while macrophages and dendritic cells showed a similar extent of infiltration into islets both with or without beta cells. TNF-α was detected in 25.0 (4.3–46.9)% of macrophages and 11.8 (0–40.0)% of dendritic cells infiltrating the islets in samples from each patient, but not at all in T cells. IL-1β was detected in 1.8 (0–11.3)% of T cells infiltrating the islets with beta cells, while it was found in 19.2 (0–35.3)% of macrophages or 10.7 (0–31.3)% of dendritic cells infiltrating the islets in samples from each patient (all values median [range]).Conclusions/interpretationMacrophages and dendritic cells infiltrate the islets and produce inflammatory cytokines (TNF-α and IL-1β) during the development of type 1A diabetes.

Demonstration of Two Different Processes of β-Cell Regeneration in a New Diabetic Mouse Model Induced by Selective Perfusion of Alloxan

To clarify the regeneration process of pancreatic β-cells, we established a new mouse model of diabetes induced by selective perfusion of alloxan after clamping the superior mesenteric artery. In this model, diabetes could be induced by the destruction of β-cells in alloxan-perfused segments, while β-cells in nonperfused segments were spared. Intraperitoneal glucose tolerance tests showed glucose intolerance, which gradually ameliorated and was completely normalized in 1 year with a concomitant increase of insulin content in the pancreas. Histological examination showed neoislet formation in the alloxan-perfused segment and the proliferation of spared β-cells in the nonperfused segment. In the alloxan-perfused segment, despite a marked reduction of islets in size and number at an early stage, both the number of islets, including islet-like cell clusters (ICCs), and the relative islet area significantly increased at a later stage. Increased single β-cells and ICCs were located in close contact with duct cell lining, suggesting that they differentiated from duct cells and that such extra-islet precursor cells may be important for β-cell regeneration in β-cell–depleted segment. In addition to β-cells, some nonhormone cells in ICCs were positive for nuclear insulin promoter factor 1, which indicated that most, if not all, nonhormone cells positive for this factor were β-cell precursors. In the nonperfused segment, the islet area increased significantly, and the highest 5-bromo-2-deoxyuridine–labeling index in β-cells was observed at day 5, while the number of islets did not increase significantly. This indicated that the regeneration of islet endocrine cells occurs mostly through the proliferation of preexisting intra-islet β-cells in the nonperfused segment. In conclusion, the regeneration process of β-cells varied by circumstance. Our mouse model is useful for studying the mechanism of regeneration, since differentiation and proliferation could be analyzed separately in one pancreas.

Cellular Hypoxia of Pancreatic β-Cells Due to High Levels of Oxygen Consumption for Insulin Secretion in Vitro

Cellular oxygen consumption is a determinant of intracellular oxygen levels. Because of the high demand of mitochondrial respiration during insulin secretion, pancreatic β-cells consume large amounts of oxygen in a short time period. We examined the effect of insulin secretion on cellular oxygen tension in vitro. We confirmed that Western blotting of pimonidazole adduct was more sensitive than immunostaining for detection of cellular hypoxia in vitro and in vivo. The islets of the diabetic mice but not those of normal mice were hypoxic, especially when a high dose of glucose was loaded. In MIN6 cells, a pancreatic β-cell line, pimonidazole adduct formation and stabilization of hypoxia-inducible factor-1α (HIF-1α) were detected under mildly hypoxic conditions. Inhibition of respiration rescued the cells from becoming hypoxic. Glucose stimulation decreased cellular oxygen levels in parallel with increased insulin secretion and mitochondrial respiration. The cellular hypoxia by glucose stimulation was also observed in the isolated islets from mice. The MIN6 cells overexpressing HIF-1α were resistant to becoming hypoxic after glucose stimulation. Thus, glucose-stimulated β-cells can become hypoxic by oxygen consumption, especially when the oxygen supply is impaired.

High titres of IgA antibodies to enterovirus in fulminant type-1 diabetes

Aims/hypothesisWe have recently proposed that fulminant type-1 diabetes is a novel subtype of type-1 diabetes with abrupt onset of insulin-deficient hyperglycaemia without islet-related autoantibodies. The pathogenesis is still unknown, but flu-like symptoms are frequently observed before the onset of disease of this subtype. Enterovirus infection is a candidate environmental factor causing type-1 diabetes. The aim of this study was to determine whether enterovirus infection contributes to the development of fulminant type-1 diabetes.MethodsWe investigated 19 patients with recent-onset fulminant type-1 diabetes, 18 patients with recent-onset typical type-1A diabetes, and 19 healthy controls. IgM, IgG, and IgA subclasses of antibodies to enterovirus were determined by ELISA.ResultsIgA antibody titres to enterovirus were significantly higher in fulminant type-1 diabetes than in typical type-1A diabetes (p=0.033) and controls (p=0.0003). IgM antibodies to enterovirus were not detected in any subject. IgG titres were lower in autoimmune diabetes than fulminant type and controls (p=0.014 and 0.019, respectively).Conclusions/interpretationHigh titres of enterovirus IgA antibodies in serum suggest recurrent enterovirus infection in fulminant type-1 diabetic patients, indicating higher susceptibility to enteroviral infections among them. Such infections might have pathogenetic importance in the triggering of fulminant type-1 diabetes.

Occurrence of IDDM during interferon therapy for chronic viral hepatitis

We report a case of IDDM which occurred during interferon therapy for chronic hepatitis. A 31-year-old man intermittently received 2.5 x 10(8) units of alpha-IFN and 1 x 10(8) units of beta-IFN for treatment of chronic viral hepatitis type B. Four years after the beginning of IFN therapy, he acutely developed moderate hyperglycemia and severe ketonuria with positive islet cell antibody, and then 28 units/day of insulin injection was started. After the start of insulin therapy, there was a remission period for about 3 years but insulin-dependency recurred thereafter. The clinical course of this case indicates that IFN therapy precedes IDDM. During and after IFN therapy we should consider the possibility of occurrence of IDDM as well as other autoimmune diseases and observe the clinical course carefully.