Chizuko Inada

Mouse islet cell lysis mediated by interleukin-1-induced Fas

Summary This study was conducted to investigate the possible involvement of Fas in β-cell death in insulitis of Type 1 (insulin-dependent) diabetes mellitus. Although primary cultured Balb/c mouse islet cells did not express Fas mRNA, 4–12 hours of treatment with 102-105 U/l of mouse interleukin-1 α (IL-1α) induced the expression of Fas mRNA. Surface Fas expression was detected by immunofluorescence flow cytometry using a non-cytolytic anti-Fas monoclonal antibody after 6 or 12 h of incubation with 103 U/l of IL-1α. Primary islet cells were resistant to an agonistic anti-Fas monoclonal antibody. However, 12 h pretreatment with IL-1α sensitized islet cells to its cytolytic effect. Significant cell death was observed 24 h after the addition of anti-Fas, and progressively increased until 72 h, when specific 51Cr release was 72 ± 6 %. Agarose gel electrophoresis of DNA extracted from cells exposed to IL-1α and agonistic anti-Fas showed internucleosomal DNA fragmentation, a hallmark of apoptotic cell death. Since the Fas antibody showed no cross-reactive activity of tumour necrosis factor (TNF), the cytotoxic effect was not mediated by TNF receptors. A protein synthesis inhibitor cycloheximide augmented Fas-mediated islet cell death. The Fas-mediated killing of islet cells was not l-arginine-dependent, or blocked by NG-monomethyl-l-arginine. β-TC1 cells also expressed Fas mRNA when exposed to IL-1α or IL-1α plus interferon-γ. These observations suggest that Fas-mediated apoptosis may be a mechanism of islet cell death in autoimmune insulitis. [Diabetologia (1996) 39: 1306–1312]

Pancreatic β-Cell–Selective Production of Tumor Necrosis Factor-α Induced by Interleukin-1

Cytokines have been regarded as effector molecules responsible for +-cell death and major histocompatibility complex hyperexpression in endocrine pancreas of type I diabetes. However, the mechanism that results in +-cell–selective destruction has not been elucidated. We demonstrated in this study, using cell lines of transformed mouse +-cells and α-cells, that only pancreatic +-cells but not α-cells produced tumor necrosis factor-α when exposed to interleukin-1 +. Northern blot analysis confirmed the +-cell-selective expression of tumor necrosis factor-α mRNA. Interleukin-1 + also provoked tumor necrosis factor-α mRNA expression in vitro by normal mouse islet cells. Because tumor necrosis factor-α has been shown to potentiate +-cell cytotoxicity of interleukin-1 and interferon-gamma, tumor necrosis factor-α produced in situ by +-cells might be self-destructive. In fact, a low dose of interleukin-1 + in combination with a low dose of interferon-gamma preferentially injured +-cells. Hence endogenous tumor necrosis factor-α production by +-cells may be involved in +-cell–selective destruction in type 1 diabetes.

Combined measurements of GAD65 and ICA512 antibodies in acute onset and slowly progressive IDDM

Autoantibodies to 65 kD glutamic acid decarboxylase (GADAA) and ICA512 (ICA512AA) were measured by radioimmunoassays using as antigens in vitro transcribed and translated [35S]-methionine-labeled human GAD65 and ICA512 (IA-2). The prevalence of GADAA and ICA512AA in sera from 87 patients with IDDM was 39 and 23%, respectively. The frequency and titer of ICA512AA declined sharply within 5 years after the onset of IDDM. Among patients tested within 4 years after diagnosis, the prevalence of ICA512AA was significantly higher in acute onset IDDM than in slowly progressive IDDM (37 versus 6%, P < 0.025) irrespective of age, while there was no difference in GADAA frequency between acute onset and slowly progressive subtypes (51 versus 63%). A total of two patients out of 121 patients with NIDDM were positive for GADAA, and two other NIDDM patients, who were suffering from sarcoidosis, were positive for ICA512AA. Neither of the antibodies were positive in sera from four atypical NIDDM patients, aged < 20 years, who showed ketosis at onset and required insulin followed by excellent metabolic control with diet restriction alone. These observations suggest that ICA512AA are associated with rapid progression of beta cell damage in IDDM. ICA512 radioassay, in combination with GAD assay may provide a useful diagnostic marker for IDDM especially in youth.

Poly(ADP-ribose) synthesis induced by nitric oxide in a mouse β-cell line

Abstract Nitric oxide (NO) has been implicated as an immunological effector molecule that mediates β-cell dysfunction associated with Type 1 diabetes. To assess whether no induces poly(ADP-ribose) synthesis in islet cells, we examined the effect of nitroprusside on islet cells. The exposure of mouse islet cells and a β-cell line (βTC1) to 0.05–0.2 mM nitroprusside resulted in the reduction of intracellular nicotinamide adenine dinucleotide (NAD) levels. Nitroprusside stimulated poly(ADP-ribose) synthetase activity in βTC1 cells. An inhibitor of poly(ADP-ribose) synthetase, 3-aminobenzamide, prevented both NAD decrease and poly ADP-ribosylation. These observations suggest that NO-induced pancreatic β-cell damage may be ascribable to the activation of poly(ADP-ribose) synthetase that results in the decrease of NAD content.

Association of troglitazone-induced liver injury with mutation of the cytochrome P450 2C19 gene

An anti-diabetic agent, troglitazone, was withdrawn from the market because of its association with liver injury. However, the mechanism of the injury has not been elucidated. We examined, retrospectively, the frequency of the polymorphisms of the cytochrome P450 (CYP) 2C19 and 2D6 genes in eight patients with type 2 diabetes who had troglitazone-induced liver injury and 31 subjects who tolerated troglitazone well. Polymorphisms of CYP 2C19 and 2D6 genes were analyzed by polymerase chain reaction using peripheral white blood cells. The incidence of mutations was compared with known population data for the Japanese. Homozygous or compound heterozygous mutations in CYP 2C19 alleles were found in four of the eight (50.0%) patients with troglitazone-induced liver injury. This rate was significantly higher than that in patients without liver injury (four of 31, 12.9%). The frequency of P450 2D6 mutations was the same in both groups. In conclusion, troglitazone-induced liver injury occurred more frequently in subjects with the CYP 2C19 mutations in Japanese patients.

Adding of Sitagliptin on Insulin Therapy Effectively and Safely Reduces a Hemoglobin A1c Level and Glucose Fluctuation in Japanese Patients with Type 2 Diabetes

Aims. Efficacy and safety of DPP-4 inhibitor, sitagliptin, add-on therapy to insulin were investigated in Japanese patients with type 2 diabetes. Subjects and Methods. Two hundred and sixteen patients (126 men, 65 ± 12 years old, BMI 24.9 ± 4.5, means ± S.D.) who had been treated by insulin alone or insulin combined with other oral hypoglycemic agents (OHAs) were recruited, and sitagliptin was added for 3 months. Results. HbA1c was significantly decreased after 3 months of add-on therapy as a whole (8.56 ± 1.50% to 7.88 ± 1.25%, P < 0.0001). Body weight did not change and insulin dosage was significantly (P < 0.0001) decreased for 3 months. Furthermore, day-to-day glucose variability was significantly reduced (18.3 ± 9.1 to 16.1 ± 8.1%, P < 0.05). In stepwise multiple regression analysis on ΔHbA1c as an outcome variable, the higher baseline HbA1c value and a preserved CPR were selected as significant predictive variables. Fifteen patients complained of mild hypoglycemia without any assistance during 3 months of sitagliptin add-on, while no severe hypoglycemic episode was reported. Conclusions. Add-on of sitagliptin to ongoing insulin therapy effectively reduced either HbA1c level or glucose fluctuation and could be a practical and well-tolerated alternative to treat Japanese patients with type 2 diabetes who had been inadequately controlled by insulin with or without other OHAs.

Classification and characteristics of interferon‐related diabetes mellitus in Japan

Aim:  The aim of this study was to assess the classification and clinical characteristics of interferon (IFN)‐related diabetes.

A case of an undifferentiated small cell carcinoma of the esophagus with a primary abdominal mass

SummaryThis paper reports a case with an undifferentiated carcinoma of the esophagus which primarily developed symptoms due to metastatic lesions. The case was a 59-year-old woman with a primary manifestation of an abdominal mass and with subsequent dysphagia. A protruding lesion with ulceration was found at the lower third of the thoracic esophagus by endoscopic examination and was histologically proved to be an undifferentiated carcinoma by biopsy. The abdominal mass was initially thought to be due to metastasis to an abdominal lymph node based on the diagnosis image finding at admission, but it was consequently found by autopsy to be a metastatic tumor in the liver. Therefore, undifferentiated carcinoma of the esophagus should be take into account for differential diagnosis of an abdominal mass.

Determining the breast-feeding interruption schedule after administration of123I-iodide

Radioactivity after administration of123I-sodium iodide was measured in breast milk samples obtained from a patient with postpartum thyroiditis. The breast milk was collected over 93 h during the infant’s regular feeding times. The radioactivity in the breast milk was calculated with a123I capsule of the same lot number as the standard source.123I was excreted exponentially with an effective half-life of 5.5 h; 2.5% of the total radioactivity administered was excreted in the breast milk over the 93 h, 95% of which was excreted within the first 24 h, and 98.2% within 36 h.The first milk sample collected at 7 h after administration of the radiopharmaceutical contained 48.5% of the total radioactivity excreted. We estimated the potential absorption of radioactivity to an infant’s thyroid in uninterrupted breast-feeding to be 30.3 mGy. With a 24-hour interruption, the absorbed radioactivity would be 1.25 mGy; with a 36-hour interruption, it would be 0.24 mGy.According to our calculations, breast feeding should be curtailed for 36 h to reduce the infant’s exposure to123I radioactivity. By using a correction factor based on maximum radioactivity from another123I capsule of the same lot, we were able to ascertain the appropriate protocol for our patient and establish a measurement method that can be applied in similar clinical situations.

Endogenous tumor necrosis factor-α production by a pancreatic β-cell line: Inhibitory effects of hydrocortisone and nicotinamide

Abstract The purpose of this study was to examine regulation of interleukin-1(IL-1)-induced tumor necrosis factor-α (TNF-α) production by a mouse β-cell line (βTC1). Three-hour incubation of βTC1 cells with 5 U ml of IL-1β results in the expression of TNF-α mRNA and intracellular accumulation of TNF-α. It has been shown that glucocorticoids and immunosuppressive agents such as cyclosporin and FK-506 inhibit TNF-α generation by T-lymphocytes and monocytes. Hydrocortisone of 1 and 10 μmol l suppressed TNF-α mRNA levels and the TNF-α content of βTC1 cells exposed to IL-1β, whereas neither cyclosporin nor FK-506 altered the TNF-α content. Nicotinamide of 5–10 mmol l also reduced TNF-α mRNA and TNF-α protein levels in βTC1 cells. Addition of exogenous TNF-α did not inhibit IL-1-induced transcription of TNF-α gene. These observations support the potential therapeutic role of glucocorticoids and nicotinamide in protecting β-cells against cytokine-mediated damage, although glucocorticoid agonists have hyperglycemic metabolic effects.