Retinoids differentially regulate the progression of autoimmune diabetes in three preclinical models in mice

Retinoids have a variety of biological activities, including immunomodulatory action in a number of inflammatory and autoimmune conditions. Considering the pathogenesis of type 1 diabetes mellitus (T1D), in this study we examined the potential role for retinoids, etretinate and all-trans-retinoic acid (ATRA) in preclinical models of human T1D. When administered prophylactically to CBA/H mice made diabetic with multiple low doses of streptozotocin (MLD-STZ), both drugs effectively prevented clinical signs of diabetes. Prevention of T1D was associated with reduced emergence of primed (autoreactive) CD4(+) CD25(+) T cells, but not with the emergence of Foxp3(+) Treg in the peripheral compartments. Moreover, the animals receiving ATRA exhibited reduced Th1/Th17 response and nitric oxide (NO) production in the peripheral lymphoid tissues, thus shifting the balance towards the anti-inflammatory cytokines. In NOD mice with spontaneous form of diabetes, ATRA prophylaxis, starting at a time point immediately before T1D onset, markedly reduced hyperglycemia and incidence of the disease. However. administration of ATRA to NOD mice in which the proportion and function of CD4(+)Foxp3(+) Treg cells was abrogated by cyclophosphamide (CY), failed to permit progression to T1D. These findings suggest that effectiveness of T1D suppression by retinoids depends on the presence of Tregs which down-modulate immunoinflammatory events at the second "check-point" and allow diabetes progression. (C) 2009 Elsevier Ltd. All rights reserved.Ministry of Science and Technology of the Republic of Serbia [143029B

Retinoids differentially regulate the progression of autoimmune diabetes in three preclinical models in mice

Retinoids have a variety of biological activities, including immunomodulatory action in a number of inflammatory and autoimmune conditions. Considering the pathogenesis of type 1 diabetes mellitus (T1D), in this study we examined the potential role for retinoids, etretinate and all-trans-retinoic acid (ATRA) in preclinical models of human T1D. When administered prophylactically to CBA/H mice made diabetic with multiple low doses of streptozotocin (MLD-STZ), both drugs effectively prevented clinical signs of diabetes. Prevention of T1D was associated with reduced emergence of primed (autoreactive) CD4(+) CD25(+) T cells, but not with the emergence of Foxp3(+) Treg in the peripheral compartments. Moreover, the animals receiving ATRA exhibited reduced Th1/Th17 response and nitric oxide (NO) production in the peripheral lymphoid tissues, thus shifting the balance towards the anti-inflammatory cytokines. In NOD mice with spontaneous form of diabetes, ATRA prophylaxis, starting at a time point immediately before T1D onset, markedly reduced hyperglycemia and incidence of the disease. However. administration of ATRA to NOD mice in which the proportion and function of CD4(+)Foxp3(+) Treg cells was abrogated by cyclophosphamide (CY), failed to permit progression to T1D. These findings suggest that effectiveness of T1D suppression by retinoids depends on the presence of Tregs which down-modulate immunoinflammatory events at the second "check-point" and allow diabetes progression. (C) 2009 Elsevier Ltd. All rights reserved.Ministry of Science and Technology of the Republic of Serbia [143029B

Does macrophage migration inhibitory factor precipitates obesity-associated type 2 diabetes development - an animal study

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Deletion of macrophage migration inhibitory factor promotes obesity-associated insulin resistance while attenuating inflammation in mice fed a high-fat diet

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The role of macrophage migration inhibitory factor in obesity-associated type 2 diabetes

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Deletion of macrophage migration inhibitory factor promotes obesity-associated insulin resistance while attenuating inflammation in mice fed a high-fat diet

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Galectin-3 deficiency reduces immune-mediated beta cell destruction in vitro

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T cells cooperate with palmitic acid in induction of beta cell apoptosis

Background: Diabetes is characterized by progressive failure of insulin producing beta cells. It is well known that both saturated fatty acids and various products of immune cells can contribute to the reduction of beta cell viability and functionality during diabetes pathogenesis. However, their joint action on beta cells has not been investigated, so far. Therefore, we explored the possibility that leukocytes and saturated fatty acids cooperate in beta cell destruction. Results: Rat pancreatic islets or insulinoma cells (RIN) were co-cultivated with concanavalin A (ConA)-stimulated rat lymph node cells (LNC), or they were treated with cell-free supernatants (Sn) obtained from ConA-stimulated spleen cells or from activated CD3(+) cells, in the absence or presence of palmitic acid (PA). ConA-stimulated LNC or Sn and PA cooperated in inducing caspase-3-dependent RIN cell apoptosis. The observed effect of PA and Sn on RIN cell viability was mediated by p38 mitogen-activated protein kinase (MAPK)-signaling and was achieved through auto-destructive nitric oxide (NO) production. The cooperative effect of Sn was mimicked with the combination of interleukin-1 beta, interleukin-2, interleukin-6, interleukin-17, interferon-gamma and tumor necrosis factor-alpha. Conclusion: These results imply that stimulated T cells produce cytokines that cooperate with saturated free fatty acids in beta cell destruction during diabetes pathogenesis.Serbian Ministry of Science [143029A]; Alexander von Humboldt Foundation (Bonn, Germany); EFSD/AstraZeneca Young Investigator Awar

Macrophage migration inhibitory factor stimulates interleukin-17 expression and production in lymph node cells

Interleukin (IL)-17 is a pro-inflammatory cytokine produced by recently described T helper type 17 (Th17) cells, which have critical role in immunity to extracellular bacteria and the pathogenesis of several autoimmune disorders. IL-6 and transforming growth factor (TGF)-beta are crucial for the generation of Th17 cells in mice, while the production of IL-17 is supported by various cytokines, including IL-23, IL-1 beta, IL-21, IL-15 and tumour necrosis factor (TNF)-alpha. In this study, the influence of a multifunctional cytokine, macrophage migration inhibitory factor (MIF), on IL-17 production in mice was investigated. Treatment of lymph node cells (LNCs) with recombinant MIF up-regulated mitogen-stimulated IL-17 expression and secretion. Additionally, LNCs from MIF knockout mice (mif(-/-)) had severely impaired production of IL-17, as well as of IL-1 beta, IL-6, IL-23 and TGF-beta. When stimulated with recombinant IL-1 beta, IL-23 or TNF-alpha, mitogen-triggered mif(-/-) LNCs were fully able to achieve the IL-17 production seen in wild-type (WT) LNCs, while the addition of IL-6 and TGF-beta had no effect. Finally, after injection of mice with complete Freund's adjuvant, secretion of IL-17 as well as the number of IL-17-positive cells was significantly lower in the draining lymph nodes of mif(-/-) mice in comparison with WT mice. The effect of MIF on IL-17 production was dependent on p38, extracellular signal-regulated kinase (ERK), Jun N-terminal kinase (JNK) and Janus kinase 2/signal transducer and activator of transcription 3 (Jak2/STAT3), and not on nuclear factor (NF)-kappa B and nuclear factor of activated T cells (NFAT) signalling. Bearing in mind the contribution of MIF and IL-17 to the pathology of inflammatory and autoimmune disorders, from the results presented here it seems plausible that targeting MIF biological activity could be a valid therapeutic approach for the treatment of such diseases.Serbian Ministry of Science [143029B

Dried leaf extract of Olea europaea ameliorates islet-directed autoimmunity in mice

The health-promoting effects of various constituents of the olive tree (Olea europaea) are mainly associated with hypoglycaemic and insulin-sensitising activities and have been widely demonstrated in the metabolic syndrome and type 2 diabetes. However, their biological activity in autoimmune type I diabetes (TID) is poorly characterised. Therefore, the influence of O. europaea-derived components present in dry olive leaf extract (DOLE) was examined in two established preclinical models of human TID, which differ in some aspects of diabetogenesis: multiple low-dose streptozotocin-induced diabetes in susceptible C57BL/6 and CBA/H mouse strains; cyclophosphamide-accelerated diabetes in non-obese diabetic mice. In both T I D models, in vivo administration of DOLE significantly reduced clinical signs of diabetes (hyperglycaemia and body weight loss) and led to complete suppression of histopathological changes in pancreatic islets. In line with these, insulin expression and release were restored in DOLE-treated mice. Interestingly, inducible NO synthase expression and NO production were significantly elevated in peripheral tissues but were down-regulated within the local environment of the endocrine pancreas. This interference was reflected in NO-mediated suppression of T lymphocyte proliferation and lower production of the proinflammatory cytokines interferon-gamma, IL-17 and TNF-alpha in the spleen. with subsequent blockade of beta-cell destruction. The results suggest that DOLE interferes with development of autoimmune diabetes by down-regulating production of proinflammatory and cytotoxic mediators. Therefore, the potential use of a DOLE-enriched diet for prophylaxis/treatment of human T I D. and possibly other autoimmune diseases, is worthy of further investigation.Serbian Ministry of Science [143029B