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DJ Hill, J Petrik, E Arany, TJ McDonald, and TL Delovitch

Interleukin-1beta (IL-1beta), tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) contribute to the initial stages of the autoimmune destruction of pancreatic beta cells. IL-1beta is released by activated macrophages resident within islets, and its cytotoxic actions include a stimulation of nitric oxide (NO) production and the initiation of apoptosis. Insulin-like growth factors (IGFs)-I and -II prevent apoptosis in non-islet tissues. This study investigated whether IGFs are cytoprotective for isolated islets of Langerhans from non-obese diabetic mice (NOD) mice exposed to cytokines. Pancreatic islets isolated from 5-6-week-old, pre-diabetic female NOD mice were cultured for 48 h before exposure to IL-1beta (1 ng/ml), TNF-alpha (5 ng/ml), IFN-gamma (5 ng/ml) or IGF-I or -II (100 ng/ml) for a further 48 h. The incidence of islet cell apoptosis was increased in the presence of each cytokine, but this was significantly reversed in the presence of IGF-I or -II (IL-1beta control 3.5+/-1.6%, IL-1beta 1 ng/ml 27.1+/-5.8%, IL-1beta+IGF-I 100 ng/ml 4.4+/-2.3%, P<0.05). The majority of apoptotic cells demonstrated immunoreactive glucose transporter 2 (GLUT-2), suggesting that they were beta cells. Islet cell viability was also assessed by trypan blue exclusion. Results suggested that apoptosis was the predominant cause of cell death following exposure to each of the cytokines. Co-incubation with either IGF-I or -II was protective against the cytotoxic effects of IL-1beta and TNF-alpha, but less so against the effect of IFN-gamma. Exposure to cytokines also reduced insulin release, and this was not reversed by incubation with IGFs. Immunohistochemistry showed that IGF-I was present in vivo in islets from pre-diabetic NOD mice which did not demonstrate insulitis, but not in islets with extensive immune infiltration. Similar results were seen for IGF-binding proteins (IGFBPs). These results suggest that IGFs protect pre-diabetic NOD mouse islets from the cytotoxic actions of IL-1beta, TNF-alpha and IFN-gamma by mechanisms which include a reduction in apoptosis.

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E Strandell and S Sandler

Abstract

The aim of the present study was to examine if the islet donor gender influences the β-cell sensitivity to possible mediators of β-cell destruction in insulin-dependent diabetes mellitus (IDDM). We have currently addressed this issue by comparing the action of the cytokine interleukin-1β (IL-1β) and the alkylating agent streptozotocin (STZ), on isolated pancreatic islets derived from prediabetic female and male nonobese diabetic (NOD) mice. In this mouse strain the females have a much higher incidence of spontaneous IDDM than the males. Pancreatic islets were isolated from female and male mice of the same litter, cultured for 6 days and thereafter either 5–50 U/ml IL-1β were added for 48 h or 1·8 mm STZ for 30 min. The cytokine exposure caused a strong increase in the medium insulin accumulation in the cultures of islets obtained from both males and females. The insulin and DNA contents were similar when comparing female and male islets before and after cytokine exposure. The male pancreatic islets exhibited a higher rate of islet glucose oxidation than islets obtained from females after IL-1β addition. Non-cytokine treated islets from males showed a higher insulin content compared with corresponding female islets. After IL-1β addition male and female islets had a similar inhibition of insulin secretion following stimulation by glucose. On the other hand, islets of both genders were equally sensitive to the inhibitory action of STZ, when studied 6 days after STZ incubation, as assessed by glucose oxidation and insulin release experiments. In conclusion the data of the present study did not demonstrate a clear gender difference in the islet β-cell sensitivity to immune mediated suppression by IL-1β or alkylation damage in IDDM-prone NOD mice. However, it cannot be excluded that in vivo, under the influence of sex hormones, a decisive alteration in β-cell sensitivity to damage might develop.

Journal of Endocrinology (1997) 153, 81–86

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G Papaccio, E Ammendola, and FA Pisanti

Pancreases of untreated and nicotinamide (NIC)-treated pre-diabetic (10-week-old) and overtly diabetic (25-week-old) female NOD (non-obese diabetic) mice and of NON (non-obese non-diabetic) control mice were studied, with the following results. (1) Islets and ducts of overtly diabetic untreated NOD mice (25-week-old) were found to express low levels of MHC class I and II molecules, like NON controls, and high levels of adhesive molecules. (2) NIC was able to slightly affect glycaemia and insulitis, slowing down diabetes progression. Moreover it significantly decreased MHC class II expression (but not class I) in vivo by week 10, and significantly enhanced intercellular adhesion molecule-1 (ICAM-1) expression, mainly by week 25, within the pancreas, where 5-bromo-2'-deoxyuridine positive nuclei and insulin positive cells were present, demonstrating that a stimulation of endocrine cell proliferation occurs. (3) In addition, NIC partly counteracted the fall of superoxide dismutase levels, observed in untreated diabetic NOD animals. (4) In vitro studies demonstrated that NIC: (i) was able to significantly reduce nitrite accumulation and to increase NAD+NADH content significantly, and (ii) was able to increase the levels of interleukin-4, a T helper 2 lymphocyte (Th2) protective cytokine, and of interferon-alpha (IFN-alpha), which is known to be able to induce MHC class I and ICAM-1 but not MHC class II expression, as well as IFN-gamma, which is also known to be able to induce MHC class I and ICAM-1 expression. The latter, although known to be a proinflammatory Th1 cytokine, has also recently been found to exert an anti-diabetogenic role. This study therefore clearly shows that adhesive mechanisms are ongoing during the later periods of diabetes in pancreatic ducts of NOD mice, and suggests they may be involved in a persistence of the immune mechanisms of recognition, adhesion and cytolysis and/or endocrine regeneration or differentiation processes, as both NIC-increased ICAM-1 expression and 5-bromo-2'-deoxyuridine positivity imply. The effects of NIC on MHC class II (i.e. a reduction) but not class I, and, mainly, on ICAM-1 expression (i.e. an increase), together with the increase in Th2 protective cytokine levels are very interesting, and could help to explain its mechanism of action and the reasons for alternate success or failure in protecting against type 1 diabetes development.

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Chun Zeng, Xin Yi, Danny Zipris, Hongli Liu, Lin Zhang, Qiaoyun Zheng, Krishnamurthy Malathi, Ge Jin, and Aimin Zhou

autoimmune responses ( Anderson & Bluestone 2005 ). NOD mice are an ideal model of spontaneous type 1 diabetes, a T-cell-mediated autoimmune disease. Results from histological studies have indicated that infiltration of immune cells, including macrophages and

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A G Kayali, A Stotland, K V Gunst, M Kritzik, G Liu, S Dabernat, Y-Q Zhang, W Wu, and N Sarvetnick

of NOD mice on embryonic day 16. All animal experiments were performed in accordance with the ethical guidelines specified by the Scripps Research Institute. Pancreatic ductal cell purification Cells of the

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S Morimoto, C A Mendoza-Rodríguez, M Hiriart, M E Larrieta, P Vital, and M A Cerbón

-cell death in STZ-diabetic mice and nonobese diabetic (NOD) mice. NOD mice spontaneously develop auto-immune diabetes with remarkable similarity to human insulin-dependent diabetes mellitus (IDDM) ( O’Brien et al. 1997 ). Injection of STZ induces

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Marta Montolio, Montse Biarnés, Noèlia Téllez, Jessica Escoriza, Joan Soler, and Eduard Montanya

mostly limited to islets transplanted to non obese diabetic (NOD) mice ( Gysemans et al. 2000 , 2003 ). Moreover, direct evidence of the presence of the cytokine in islet grafts has not yet been provided, and the question of the cellular origin of

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J M Mellado-Gil and M Aguilar-Diosdado

pancreatic islets of NOD mice with spontaneous and cyclophosphamide-accelerated diabetes. Diabetologia 41 1381 –1388. Castaño L & Eisenbarth GS 1990 Type 1 diabetes: a chronic autoimmune disease of human, mouse, and rat

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Eva Kassi and Athanasios G Papavassiliou

obesity . Nature Medicine 7 941 – 946 . Yoon JW Yoon CS Lim HW Huang QQ Kang Y Pyun KH Hirasawa K Sherwin RS Jun HS 1999 Control of autoimmune diabetes in NOD mice by GAD expression or suppression in beta cells . Science 284

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Haiyong Chen, Hui-Yao Lan, Dimitrios H Roukos, and William C Cho

( Plaisance et al . 2006 ). Interestingly, studies of miRNA expression profiles shows that the increase in miR-29a/b/c in the islets of prediabetic NOD mice is also associated with impaired glucose-induced insulin secretion by diminishing the expression of