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Yoko Yagishita, Akira Uruno, Dionysios V Chartoumpekis, Thomas W Kensler and Masayuki Yamamoto

partially prevented by treatment with Nrf2 inducers, such as sulforaphane. Although the STZ-induced diabetic model develops insulitis, β-cell damage is induced primarily due to the chemical toxicity of STZ in these cells, and thus, the damage does not

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Marika Bogdani, Angela M Henschel, Sanjay Kansra, Jessica M Fuller, Rhonda Geoffrey, Shuang Jia, Mary L Kaldunski, Scott Pavletich, Simon Prosser, Yi-Guang Chen, Åke Lernmark and Martin J Hessner

Introduction Type 1 diabetes (T1D) is an autoimmune disease characterized by immunocyte infiltration of the pancreatic islets (insulitis) and destruction of the insulin-secreting β cells. Diabetes in the biobreeding (BB) rat exhibits many

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Astrid Chamson-Reig, Edith J Arany, Kelly Summers and David J Hill

generation of nitric oxide, in response to the actions of IFNγ, TNFα and IL-1β. The non-obese diabetic (NOD) mouse is a well-studied model of spontaneous type 1 diabetes in which predominantly the female animals develop an insulitis between 5 and 8 weeks of

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Jennifer A Crookshank, Daniel Serrano, Gen-Sheng Wang, Christopher Patrick, Baylie S Morgan, Marie-France Paré and Fraser W Scott

prediabetic or nondiabetic individual. It is important to perform this analysis before insulitis is present to avoid confounding effects of infiltrating immune cells. In the BioBreeding diabetes-prone (BBdp) rats from our colony, classic insulitis is not

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James C Needell, Madalyn N Brown and Danny Zipris

.WR1 rat develops insulitis and diabetes ~2–4 weeks following viral infection, with a disease rate of ~60% ( Hara et al . 2012 ). Kilham rat virus (KRV)-induced diabetes is rat and strain specific and closely resembles the human disorder with respect

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M Holstad and S Sandler

In earlier studies it has been shown that prolactin (PRL) is a stimulating factor for the immune system, and it has been suggested that PRL might antagonize immunosuppressive effects of glucocorticoids. PRL has been reported to affect the cytokine secretion pattern, by elevating cytokine gene expression in macrophages, after the onset of sepsis. It also promotes the antibody response in mice where it increases the production of interferon-gamma (IFN-gamma) and inhibits interleukin-1 (IL-1) production. Due to these properties, PRL might influence the development of autoimmune type 1 diabetes. The aim of the present study was to examine the effects of two drugs; PRL and bromocriptine (BC) in vivo on the development of hyperglycemia and pancreatic insulitis in mice treated with multiple doses of streptozotocin (STZ) (40 mg/kg body weight, i.p.). The dopaminergic agonist BC is known to inhibit PRL secretion. In another set of experiments, the direct effects of PRL on the function of pancreatic islets exposed to STZ in vitro were studied. Mice treated with STZ became gradually hyperglycemic, and concomitant treatment with PRL (4 mg/kg body weight) for 21 days significantly reduced the elevation in blood glucose levels from day 10 onwards (P<0.05). Morphologic examinations of the pancreas on day 21 of mice receiving STZ injections revealed a marked insulitis, but only moderate insulitis in the STZ treated animals given PRL. BC administration (10 mg/kg body weight) in combination with STZ did not significantly affect the elevation in blood glucose levels or the insulitis. PRL or BC administration alone did not change the serum glucose concentration. This study indicates that PRL may affect hyperglycemia in the early phase of autoimmune diabetes. We suggest that it might be due to counteraction of autoimmune immunologic mechanisms and/or enhancement of beta-cell regeneration.

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Z Li, FA Karlsson and S Sandler

The aim of this study was to investigate the alpha cell population during the development of type 1 diabetes following multiple low-dose streptozotocin administration in mice. For this purpose C57BL/Ks male mice were injected with streptozotocin (40 mg/kg body weight for 5 days). Development of hyperglycemia was monitored over 28 days and a morphometric analysis of islet endocrine cells was performed. A reduction of islet cell area was observed after two injections of streptozotocin. The subsequent decrease of the area throughout the study period averaged 35%. Insulin-positive beta cells gradually disappeared from the identified islets. Hyperglycemia was present from day 7 onwards and in parallel with hyperglycemia, insulitis developed. An analysis of the alpha cell number per islet area revealed a 2- to 3-fold increase in this cell population, with the highest value on day 21. Confocal microscopy analysis of the ICA 512 protein tyrosine phosphatase revealed strong expression in the alpha cells at day 21, suggesting high secretory activity in the diabetic state. It is concluded that multiple low-dose streptozotocin treatment of C57BL/Ks male mice causes the disappearance of a fraction of the islets of Langerhans. In the remaining islet tissue an expansion of alpha cells occurs, reflecting a loss of intraislet beta cells as well as a regeneration of alpha cells.

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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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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.

Open access

Esther Nuñez-Durán, Belén Chanclón, Silva Sütt, Joana Real, Hanns-Ulrich Marschall, Ingrid Wernstedt Asterholm, Emmelie Cansby and Margit Mahlapuu

secondary antibodies (see Supplementary Table 1 for antibody information). The distribution of inflammatory cell infiltrate was assessed, and a total insulitis score was calculated as described previously ( Fukuda et al. 2008 ) in all islets present in