Regulatory T cells (Tregs) can suppress a wide variety of cell types, in diverse organ sites and inflammatory conditions. While Tregs possess multiple suppressive mechanisms, the number required for maximal function is unclear. Furthermore, whether any inter-relationship orcross-regulatory mechanisms exist that areused to orchestrate and control their utilization is unknown. Here we assessed the functional capacity of Tregs lacking the ability to secrete both interleukin-10 (IL-10) and IL-35, which individually are required for maximal Treg activity. Surprisingly, IL-10/IL-35-double deficient Tregswere fully functionalin vitro and in vivo. Loss of IL-10 and IL-35 was compensated for by a concurrent increase in cathepsin E (CTSE) expression, enhanced TRAIL (Tnfsf10)expression and soluble TRAIL release, rendering IL-10/IL-35-double deficient Tregsfunctionally dependent on TRAIL in vitro and in vivo. Lastly, while C57BL/6 Tregs are IL-10/IL-35-dependent, Balb/c Tregs, which express high levels of CTSE and enhanced TRAIL expression, are TRAIL-dependent.These data reveal that cross-regulatory pathways exist, which control the utilization of suppressive mechanisms,thereby providing Tregfunctional plasticity.
The plasticity of regulatory T cell function.
Specimen part
View SamplesCholecystokinin (CCK) is a satiety hormone produced by discrete enteroendocrine cells scattered among absorptive cells of the small intestine. CCK is released into blood following a meal; however, the mechanisms inducing hormone secretion are largely unknown. Ingested fat is the major stimulant of CCK secretion. We recently identified a novel member of the lipoprotein remnant receptor family known as immunoglobulin-like domain containing receptor 1 (ILDR1) in intestinal CCK cells and postulated that this receptor conveyed the signal for fat-stimulated CCK secretion. In the intestine, ILDR1 is expressed exclusively in CCK cells. Orogastric administration of fatty acids elevated blood levels of CCK in wild type but not ILDR1-deficient mice, although the CCK secretory response to trypsin inhibitor was retained. The uptake of fluorescently labeled lipoproteins in ILDR1-transfected CHO cells and release of CCK from isolated intestinal cells required a unique combination of fatty acid plus HDL. CCK secretion secondary to ILDR1 activation is associated with increased [Ca2+]i consistent with regulated hormone release. These findings demonstrate that ILDR1 regulates CCK release through a mechanism dependent on fatty acids and lipoproteins and that absorbed fatty acids regulate gastrointestinal hormone secretion.
Immunoglobulin-like domain containing receptor 1 mediates fat-stimulated cholecystokinin secretion.
Specimen part
View SamplesChemokines and adhesion molecules upregulated in lymphatic endothelial cells (LECs) during tissue inflammation are believed to enhance dendritic cell (DC) migration to draining lymph nodes (dLNs), but the in vivo control of this process is not well understood. By performing transcriptional profiling of LECs isolated from murine skin, we found that inflammation induced by a contact hypersensitivity (CHS) response upregulated the adhesion molecules ICAM-1 and VCAM-1 and inflammatory chemokines in LECs. Furthermore, lymphatic lineage markers like Prox-1, VEGFR3 and LYVE-1 were significantly downregulated during CHS. By contrast, skin inflammation induced by Complete Freunds adjuvant (CFA) induced a different pattern of chemokine and lymphatic marker gene expression and almost no ICAM-1 up-regulation in LECs. In FITC painting experiments, DC migration to dLNs was more strongly increased in CFA- as compared to CHS-induced inflammation. Interestingly, DC migration did not correlate with the induction of CCL21 and ICAM-1 in LECs. However, the requirement for CCR7 signaling became further pronounced during inflammation, whereas CCR7-independent signals only had a minor role in enhancing DC migration. Collectively, these findings indicate that inflammation-induced DC migration is stimulus-dependent and only moderately enhanced by LEC-induced genes other than CCL21.
Tissue inflammation modulates gene expression of lymphatic endothelial cells and dendritic cell migration in a stimulus-dependent manner.
Sex, Age, Specimen part
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