Abstract
Two major dendritic cell (DC) subsets have been described in the pancreas of mice: The CD11c+CD8α− DCs (strong CD4+ T cell proliferation inducers) and the CD8α+CD103+ DCs (T cell apoptosis inducers). Here we analyzed the larger subset of CD11c+CD8α− DCs isolated from the pancreas of pre-diabetic NOD mice for genome-wide gene expression (validated by Q-PCR) to elucidate abnormalities in underlying gene expression networks. CD11c+CD8α− DCs were isolated from 5 week old NOD and control C57BL/6 pancreas. The steady state pancreatic NOD CD11c+CD8α− DCs showed a reduced expression of several gene networks important for the prime functions of these cells, i.e. for cell renewal, immune tolerance induction, migration and for the provision of growth factors including those for beta cell regeneration. A functional in vivo BrdU incorporation test showed the reduced proliferation of steady state pancreatic DC. The reduced expression of tolerance induction genes (CD200R, CCR5 and CD24) was supported on the protein level by flow cytometry. Also previously published functional tests on maturation, immune stimulation and migration confirm the molecular deficits of NOD steady state DC. Despite these deficiencies NOD pancreas CD11c+CD8α− DCs showed a hyperreactivity to LPS, which resulted in an enhanced pro-inflammatory state characterized by a gene profile of an enhanced expression of a number of classical inflammatory cytokines. The enhanced up-regulation of inflammatory genes was supported by the in vitro cytokine production profile of the DCs. In conclusion, our data show that NOD pancreatic CD11c+CD8α− DCs show various deficiencies in steady state, while hyperreactive when encountering a danger signal such as LPS.
Highlights
Diabetes mellitus type 1 (T1DM) is caused by an autoimmune reaction to the islets of Langerhans in the pancreas resulting in an autoimmune insulitis, in which the beta cells disappear with as consequence an absolute insulin deficiency.The NOD mouse model is considered an excellent model of human T1DM and spontaneously develops an autoimmune insulitis similar to T1DM patients [1,2,3]
We have recently reported on reduced numbers of the minor population of tolerogenic CD8a+CD103+ dendritic cell (DC) in the 5 week old pre-diabetic pancreas of NOD mice [16] and hypothesized that the reduced number of these tolerogenic DC contributes to the development of progressive destructive autoimmune insulitis
Inflammation and cell migration network A high ranking network within the reduced network of maturation and inflammation consisted of the down-regulation of various inflammatory response genes (Figure S3 in File S1), such as Il10, Il12b, Ifng and Chi3l3 (YM1, an enzyme involved in alternative macrophage polarization and known for its Th2 cell promoting effects [19,20]) and the down-regulation of the costimulatory gene CD40. These findings suggest a reduced classical DC maturation of steady state NOD pancreatic CD8a2 DCs. This observation is supported by previous functional studies of our group, in which we found with regard to the DC differentiation from bone marrow precursors that the cells showed a poor differentiation into fully competent classical immune stimulatory DCs, yet deviated to another phenotype, i.e. a more ‘‘macrophage like’’ phenotype [20]
Summary
Diabetes mellitus type 1 (T1DM) is caused by an autoimmune reaction to the islets of Langerhans in the pancreas resulting in an autoimmune insulitis, in which the beta cells disappear with as consequence an absolute insulin deficiency.The NOD mouse model is considered an excellent model of human T1DM and spontaneously develops an autoimmune insulitis similar to T1DM patients [1,2,3]. With regard to the early phases of the NOD autoimmune insulitis Diana et al recently showed a transient accumulation of a small number of plasmacytoid DCs, lymphocytes and B-cells in the pancreatic islets of NOD mice at 2 weeks of age [4]. An interaction between these infiltrating cells was shown to be involved in the onset of autoimmunity against the beta cells. At the time of this larger para- and peri-islet immune cell accumulation there is a steady increase of dispersed cDCs and macrophages in the exocrine pancreas [8]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
