Combining MK626, a novel DPP-4 inhibitor, and low-dose monoclonal CD3 antibody for stable remission of new-onset diabetes in mice.

Combining immune intervention with therapies that directly influence the functional state of the β-cells is an interesting strategy in type 1 diabetes cure. Dipeptidyl peptidase-4 (DPP-4) inhibitors elevate circulating levels of active incretins, which have been reported to enhance insulin secretion and synthesis, can support β-cell survival and possibly stimulate β-cell proliferation and neogenesis. In the current study, we demonstrate that the DPP-4 inhibitor MK626, which has appropriate pharmacokinetics in mice, preceded by a short-course of low-dose anti-CD3 generated durable diabetes remission in new-onset diabetic non-obese diabetic (NOD) mice.

1,25-Dihydroxyvitamin D3 promotes tolerogenic dendritic cells with functional migratory properties in NOD mice.

The biologically active form of vitamin D, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], is able to promote the generation of tolerogenic mature dendritic cells (mDCs) with an impaired ability to activate autoreactive T cells. These cells could represent a reliable tool for the promotion or restoration of Ag-specific tolerance through vaccination strategies, for example in type 1 diabetes patients. However, successful transfer of 1,25(OH)2D3-treated mDCs (1,25D3-mDCs) depends on the capacity of 1,25(OH)2D3 to imprint a similar tolerogenic profile in cells derived from diabetes-prone donors as from diabetes-resistant donors.

Dietary supplementation with high doses of regular vitamin D3 safely reduces diabetes incidence in NOD mice when given early and long term.

High doses of the active form of vitamin D3, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], prevent diabetes in the NOD mouse but also elicit unwanted calcemic side effects. Because immune cells themselves can convert vitamin D3 into 1,25(OH)2D3 locally, we hypothesized that dietary vitamin D3 can also prevent disease. Thus, we evaluated whether dietary administration of high doses of regular vitamin D3 (800 IU/day) during different periods of life (pregnancy and lactation, early life [3-14 weeks of age], or lifelong [3-35 weeks of age]) safely prevents diabetes in NOD mice.

Deletion of STAT-1 pancreatic islets protects against streptozotocin-induced diabetes and early graft failure but not against late rejection.

Objective: Exposure of beta-cells to inflammatory cytokines leads to apoptotic cell death through the activation of gene networks under the control of specific transcription factors, such as interferon-gamma-induced signal transducer and activator of transcription (STAT)-1. We previously demonstrated that beta-cells lacking STAT-1 are resistant to cytokine-induced cell death in vitro. The aim of this study was to investigate the effect of STAT-1 elimination on immune-mediated beta-cell destruction in vivo.

Disruption of the gamma-interferon signaling pathway at the level of signal transducer and activator of transcription-1 prevents immune destruction of beta-cells.

beta-cells under immune attack are destroyed by the aberrant activation of key intracellular signaling cascades. The aim of the present study was to evaluate the contribution of the signal transducer and activator of transcription (STAT)-1 pathway for beta-cell apoptosis by studying the sensitivity of beta-cells from STAT-1 knockout (-/-) mice to immune-mediated cell death in vitro and in vivo. Whole islets from STAT-1-/- mice were completely resistant to interferon (IFN)-gamma (studied in combination with interleukin [IL]-1beta)-mediated cell death (92 +/- 4% viable cells in STAT-1-/- mice vs.

1,25-Dihydroxyvitamin D3 modulates expression of chemokines and cytokines in pancreatic islets: implications for prevention of diabetes in nonobese diabetic mice.

1,25-Dihydroxyvitamin D(3) (1,25-(OH)(2)D(3)) is an immune modulator that prevents experimental autoimmune diseases. Receptors for 1,25-(OH)(2)D(3) are present in pancreatic beta-cells, the target of an autoimmune assault in nonobese diabetic (NOD) mice. The aim of this study was to investigate the in vivo and in vitro effects of 1,25-(OH)(2)D(3) on beta-cell gene expression and death and correlate these findings to in vivo diabetes development in NOD mice.