Preservation of beta-cell function during immune-mediated, B7-1-dependent alpha-cell destruction.

Type 1 diabetes (T1D) is an autoimmune disease in which the pancreatic beta-cells are destroyed in an immune-mediated process. In one mouse model of T1D, the co-expression of the costimulatory molecule, B7-1, and the pro-inflammatory cytokine, tumor necrosis factor (TNF)-alpha, on the beta-cells leads to massive insulitis and loss of beta-cells, resulting in T1D. Here, we have investigated whether the specific loss of beta-cells is due to an intrinsic defect in the beta-cells or is a direct consequence of B7-1 expression.

Different diabetogenic potential of autoaggressive CD8+ clones associated with IFN-gamma-inducible protein 10 (CXC chemokine ligand 10) production but not cytokine expression, cytolytic activity, or homing characteristics.

Type 1 diabetes mellitus is an autoimmune disease characterized by T cell-mediated destruction of the insulin-producing beta cells in the islets of Langerhans. From studies in animal models, CD8(+) T cells recognizing autoantigens such as islet-specific glucose-6-phosphatase catalytic subunit-related protein, insulin, or glutamic acid decarboxylase (GAD) are believed to play important roles in both the early and late phases of beta cell destruction. In this study, we investigated the factors governing the diabetogenic potential of autoreactive CD8(+) clones isolated from spleens of NOD mice that had been immunized with GAD65(515-524) or insulin B-chain(15-23) peptides.

Local activation of dendritic cells leads to insulitis and development of insulin-dependent diabetes in transgenic mice expressing CD154 on the pancreatic beta-cells.

The initial events leading to activation of the immune system in type 1 diabetes are still largely unknown. In vivo, dendritic cells (DCs) are thought to be the only antigen-presenting cells (APCs) capable of activating naïve T-cells and are therefore important for the initiation of the autoimmune response. To test the effect of activating islet-associated APCs in situ, we generated transgenic mice expressing CD154 (CD40 ligand) under control of the rat insulin promoter (RIP).

TNF-alpha impairs peripheral tolerance towards beta-cells, and local costimulation by B7.1 enhances the effector function of diabetogenic T cells.

Maintenance of peripheral tolerance and inactivation of autoreactive T cells is based on a delicate balance between pro-inflammatory and protective cytokines that is poorly understood. We have here addressed how the local expression of the inflammatory cytokine TNF-alpha can impair peripheral tolerance and lead to autoreactivity. After transplantation of pancreata that are immunogenic due to beta-cell expression of B7.

An islet-homing NOD CD8+ cytotoxic T cell clone recognizes GAD65 and causes insulitis.

T cells play a central role in the development of diabetes both in man and in the non-obese diabetic (NOD) mouse. Both the CD4(+) and CD8(+) subsets of T cells are required for the normal development of IDDM in NOD mice. Islet reactive CD4(+) T cells play a clear pathogenic role as evidenced from the isolation of diabetogenic CD4(+) T cell clones.

Low expression of insulin in the thymus of non-obese diabetic mice.

Insulin is a predominant autoantigen in IDDM in man and the NOD mouse. Failure of negative selection of diabetogenic T cells in thymus may be an important pre-disposing cause of the disease. To obtain insight into negative selection against such T-cell clones the thymic expression of insulin was studied in NOD and Balb/c mice by quantitative competitive RT-PCR.

Both exogenous and endogenous interleukin-10 affects the maturation of bone-marrow-derived dendritic cells in vitro and strongly influences T-cell priming in vivo.

In order to avoid autoimmunity and excessive tissue destruction, the action of certain immunoinhibitory substances are very important for negative regulation of the immune system. Interleukin-10 (IL-10) is an important immunoregulatory cytokine which is thought to negatively affect both T cells and antigen-presenting cells in vivo. Adoptive transfer of IL-10-treated bone-marrow-derived dendritic cells (BMDCs) may be one therapeutic avenue to inhibit autoimmunity.

Histone deacetylase inhibitors: a new class of immunosuppressors targeting a novel signal pathway essential for CD154 expression.

Here we report that histone deacetylase inhibitors (HDAC-i) comprise a new class of immunosuppressive agents. HDAC-i inhibited CD4 T-cell proliferation in a dose-dependent manner, which was not caused by apoptosis or decreased viability. Although early intracellular signals such as tyrosine kinase activity and elevation of intracellular calcium concentration were not affected, the characteristic aggregation of T cells following activation was completely abrogated.

PDX-1 mediates glucose responsiveness of GAD(67), but not GAD(65), gene transcription in islets of Langerhans.

Glucose responsiveness is a fundamental metabolic feature of pancreatic beta-cells. Glucose-regulated transcription of the insulin gene is in part mediated via the homeobox transcription factor PDX-1. Another islet protein and diabetes autoantigen, glutamic acid decarboxylase (GAD), has been shown to be subject to regulation by glycemia.