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Examination of inflammatory transcripts during a transfer model of type I diabetes.

ABSTRACT: In an accompanying paper we found specific localization of diabetogenic T cells only to islets of Langerhans bearing the specific antigen. Instrumental in the specific localization was the presence of intra-islet dendritic cells bearing the β-cell-peptide-MHC complex. Here we report that the entry of diabetogenic CD4 T cells very rapidly triggered inflammatory gene expression changes in islets and vessels by up-regulating chemokines and adhesion molecules. VCAM-1 expression was notable in blood vessels and so was ICAM-1. ICAM-1 was also found on β-cells. These expression changes induced the entry of non-specific T cells that otherwise did not localize to the islets. In contrast to the entry of diabetogenic CD4 T cells, the entrance of non-specific T cells required a chemokine response and VCAM-1 expression by the islets. Interferon-gamma was important for the early gene expression changes in the islets. By microarray analysis we detected up-regulation of a group of interferon-inducible genes as early as 8 hours post T cell transfer. These studies provide a baseline to examine the development of therapeutics that can modulate islet localization of diabetogenic T cells to control this autoimmune disease.

ORGANISM(S): Mus musculus

PROVIDER: GSE26147 | GEO | 2011/02/16

SECONDARY ACCESSION(S): PRJNA135303

REPOSITORIES: GEO

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Project description:Expression of CD40 in non-hematopoietic cells has been linked to inflammation. We presented evidence that CD40, a T-cell costimulatory molecule, is expressed in human Î²-cells and the engagement of CD40 in insulinoma cells activated the NFKB and ERK1/2 pathways. CD40 activation in human islets cells induced secretion of IL-8, MCP-1 and MIP-1 Î², which is abrogated by inhibitors of NFkB and ERK1/2 inhibitors. In this study, we have studied gene expression mediated by CD40-CD40L interaction in islet cells. This approach identified 90 genes and transcripts exhibiting at least a 1.7 fold increase in their expression intensity after treatment with soluble CD40L. A significant number of genes were related to inflammation and oxidative stress. We have a strong overexpression of CXCL1 (GroÎ±), CXCL2 (Mif2) and CXCL3; chemokines belonging to CXC family structurally related to Il-8. 11 genes were selected from this group and further quantified by Real Time PCR, including CXCL1. Activation of islet cells with CD40L induced the secretion of CXCL1 in a NFKB dependent manner. Engagement of CD40 in islet cells did not induce apoptosis, neither Î²-cell death and did not enhanced TNF-Î± mediated cell death as observed in insulinoma cells. CD40 activation in insulinoma cells, results in ERK1/2 dependent phsophorylation of synapsin I, a protein associated with the exocytosis machinery in neurons and Î²-cells. However, treatment of islets with soluble CD40L did not affect glucose induced insulin secretion. It has been reported that ductal cells always present in human islet preparations express CD40 constitutively (ref). We found that CD40-CD40L interaction in ductal cells, unlike in Î²-cells, induces secretion of diabetogenic cytokines IFNÎ³ and TNF-Î±. Furthermore, incubation of islets containing ductal cells with CD40L decreased Î²-cells viability as assessed by measurement of their mitochondrial membrane potential Experiment Overall Design: We isolated islet cells from three patients. Part of islet cells from each patient has been treated with CD40L. We compared gene expression in treated cells vs untreated for each patient using dye-swap.

Project description:We demonstrate diverse roles of interferonâgamma (IFN-Î³) in the induction and regulation of immune-mediated inflammation using a transfer model of autoimmune diabetes. The diabetogenic CD4+BDC2.5 (BDC) T cell clone upon transfer into NOD.scid mice induced destruction of islets of Langerhans leading to diabetes. Administration of a neutralizing antibody to IFN-Î³ (H22) resulted in long term protection (LTP) from diabetes, with inflammation but persistence of a significant, albeit decreased numbers of Î²-cells. BDC T cells were a mixture of cells expressing high, intermediate and low levels of the T cell receptor. Clonotype-low BDC T cells were required for LTP. Furthermore, islet infiltrating leukocytes in the LTP mice contained Foxp3+CD4 T cells. Islet inflammation in both diabetic and LTP mice was characterized by heavy infiltration of macrophages. Gene expression profiles indicated that macrophages in diabetic mice were M1-type, while LTP mice contained M2-differentiated. The LTP was abolished if mice were treated with either an antibody depleting CD4 T cells, or a neutralizing antibody to CTLA-4, in this case, only at a late stage. Neutralization of IL-10, TGF-Î², GITR or CD25 had no effect. Transfer of only clonotype-high expressing BDC T cells induced diabetes but in contrast, H22 antibodies did not inhibit diabetes. While clonotype high T cells induced diabetes even when IFN-Î³ was neutralized, paradoxically, there was reduced inflammation and no diabetes if host myeloid cells lacked IFN-Î³ receptor. Hence, using monoclonal CD4 T cells, IFN-Î³ can have a wide diversity of roles, depending on the setting of the immune process. Experiment Overall Design: Pancreatic islets were laser-capture microdissected from mice injected with diabetogenic T cells. One cohort of mice also received injections with anti-interfereon gamma monoclonal antibody, which protected those mice from developing diabetes. RNA prepared from islets was amplified and analyzed by Affymetrix GeneChips. Each GeneChip was prepared from RNA pooled from 5 mice at each timepoint. GeneChips were prepared from RNA extracted at different days following injection of T cells. The following days were assayed day 0 (i.e., untreated), day 3 (for diabetic and protected islets), day 4 (diabetic and protected), day 5 (only for protected, as diabetic islets were too edematous to dissect), day 8 (diabetic and protected).

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Examination of inflammatory transcripts during a transfer model of type I diabetes.

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