Project description:Increased antigen cross-presentation but impaired cross-priming after activation of PPARγ is mediated by up-regulation of B7H1 Dendritic cells (DCs) are able to take up exogenous antigens and present antigen-derived peptides on MHC class I molecules, a process termed cross-presentation. The mannose receptor (MR), an endocytic receptor expressed on a variety of antigen-presenting cells (APCs), has been demonstrated to target soluble antigens exclusively towards cross-presentation. In this study, we investigated the role of the murine nuclear receptor peroxisome proliferator-activated receptor γ (PPARγ), a ligand-activated transcription factor with immunomodulatory properties, in MR-mediated endocytosis and cross-presentation of the model antigen ovalbumin (OVA). We could demonstrate both in vitro and in vivo that activation of PPARγ resulted in increased MR expression, which in consequence led to enhanced MR-mediated endocytosis and elevated cross-presentation of soluble OVA. Concomitantly, activation of PPARγ in DCs induced up-regulation of the co-inhibitory molecule B7H1, which, despite enhanced cross-presentation, caused an impaired activation of naive OVA-specific CD8+ T cells and the induction of T cell tolerance. These data provide a mechanistic basis for the immunomodulatory action of PPARγ which might open new possibilities in development of therapeutical approaches aimed at the control of excessive immune responses, e.g. in T cell-mediated autoimmunity.
Project description:Increased antigen cross-presentation but impaired cross-priming after activation of PPARγ is mediated by up-regulation of B7H1 Dendritic cells (DCs) are able to take up exogenous antigens and present antigen-derived peptides on MHC class I molecules, a process termed cross-presentation. The mannose receptor (MR), an endocytic receptor expressed on a variety of antigen-presenting cells (APCs), has been demonstrated to target soluble antigens exclusively towards cross-presentation. In this study, we investigated the role of the murine nuclear receptor peroxisome proliferator-activated receptor γ (PPARγ), a ligand-activated transcription factor with immunomodulatory properties, in MR-mediated endocytosis and cross-presentation of the model antigen ovalbumin (OVA). We could demonstrate both in vitro and in vivo that activation of PPARγ resulted in increased MR expression, which in consequence led to enhanced MR-mediated endocytosis and elevated cross-presentation of soluble OVA. Concomitantly, activation of PPARγ in DCs induced up-regulation of the co-inhibitory molecule B7H1, which, despite enhanced cross-presentation, caused an impaired activation of naive OVA-specific CD8+ T cells and the induction of T cell tolerance. These data provide a mechanistic basis for the immunomodulatory action of PPARγ which might open new possibilities in development of therapeutical approaches aimed at the control of excessive immune responses, e.g. in T cell-mediated autoimmunity. Comparison of murine mannose receptor negative versus mannose receptor positive bone marrow-derived DCs
Project description:This a model from the article:
A dynamical perspective of CTL cross-priming and regulation: implications for
cancer immunology.
Wodarz D, Jansen VA. Immunol Lett
2003 May 1;86(3):213-27 12706524
,
Abstract:
Cytotoxic T lymphocytes (CTL) responses are required to fight many diseases such
as viral infections and tumors. At the same time, they can cause disease when
induced inappropriately. Which factors regulate CTL and decide whether they
should remain silent or react is open to debate. The phenomenon called
cross-priming has received attention in this respect. That is, CTL expansion
occurs if antigen is recognized on the surface of professional antigen
presenting cells (APCs). This is in contrast to direct presentation where
antigen is seen on the surface of the target cells (e.g. infected cells or tumor
cells). Here we introduce a mathematical model, which takes the phenomenon of
cross-priming into account. We propose a new mechanism of regulation which is
implicit in the dynamics of the CTL: According to the model, the ability of a
CTL response to become established depends on the ratio of cross-presentation to
direct presentation of the antigen. If this ratio is relatively high, CTL
responses are likely to become established. If this ratio is relatively low,
tolerance is the likely outcome. The behavior of the model includes a parameter
region where the outcome depends on the initial conditions. We discuss our
results with respect to the idea of self/non-self discrimination and the danger
signal hypothesis. We apply the model to study the role of CTL in cancer
initiation, cancer evolution/progression, and therapeutic vaccination against
cancers.
This model was taken from the CellML repository
and automatically converted to SBML.
The original model was:
Wodarz D, Jansen VA. (2003) - version=1.0
The original CellML model was created by:
Catherine Lloyd
c.lloyd@auckland.ac.nz
The University of Auckland
This model originates from BioModels Database: A Database of Annotated Published Models (http://www.ebi.ac.uk/biomodels/). It is copyright (c) 2005-2011 The BioModels.net Team.
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To cite BioModels Database, please use: Li C, Donizelli M, Rodriguez N, Dharuri H, Endler L, Chelliah V, Li L, He E, Henry A, Stefan MI, Snoep JL, Hucka M, Le Novère N, Laibe C (2010) BioModels Database: An enhanced, curated and annotated resource for published quantitative kinetic models. BMC Syst Biol., 4:92.
Project description:Cross-presentation of tumor antigens by dendritic cells (DCs) is crucial to prime and (re-) stimulate CD8+ T cells. This process is important in initiating and maintaining an anti-tumor response. Here, we show that tumor presence of conventional type 1 DCs (cDC1), a subtype that excels in cross-presentation, correlates with response to neoadjuvant immune checkpoint blockade (ICB) in melanoma. This led us to hypothesize that patients failing to respond to ICB could benefit from enhanced cross-presentation of tumor antigens. We therefore established a cross-presentation assay to screen over 5,500 compounds for enhancers of DC cross-presentation using induced T cell proliferation as readout. We identified 145 enhancers, including AZD5582, an antagonist of inhibitor of apoptosis proteins (IAPs) cIAP1, cIAP2 and XIAP. AZD5582 treatment led to DC activation of the non-canonical nuclear factor kappa B (NF-kB) pathway, enhanced antigen import from endolysosomes into the cytosol and increased expression of genes involved in cross-presentation. Furthermore, it upregulated expression of CD80, CD86, MHC class II, CD70 and secretion of TNF by DCs. This enhanced DC activation and maturation program was observed also in tumor-bearing mice upon AZD5582 treatment, culminating into an increased frequency of systemic tumor antigen-specific CD8+ T cells. Our results merit further exploration of AZD5582 to increase antigen cross-presentation for improving the clinical benefit of ICB in unfavorable patients.
Project description:Cross-presentation of tumor antigens by dendritic cells (DCs) is crucial to prime and (re-) stimulate CD8+ T cells. This process is important in initiating and maintaining an anti-tumor response. Here, we show that tumor presence of conventional type 1 DCs (cDC1), a subtype that excels in cross-presentation, correlates with response to neoadjuvant immune checkpoint blockade (ICB) in melanoma. This led us to hypothesize that patients failing to respond to ICB could benefit from enhanced cross-presentation of tumor antigens. We therefore established a cross-presentation assay to screen over 5,500 compounds for enhancers of DC cross-presentation using induced T cell proliferation as readout. We identified 145 enhancers, including AZD5582, an antagonist of inhibitor of apoptosis proteins (IAPs) cIAP1, cIAP2 and XIAP. AZD5582 treatment led to DC activation of the non-canonical nuclear factor kappa B (NF-kB) pathway, enhanced antigen import from endolysosomes into the cytosol and increased expression of genes involved in cross-presentation. Furthermore, it upregulated expression of CD80, CD86, MHC class II, CD70 and secretion of TNF by DCs. This enhanced DC activation and maturation program was observed also in tumor-bearing mice upon AZD5582 treatment, culminating into an increased frequency of systemic tumor antigen-specific CD8+ T cells. Our results merit further exploration of AZD5582 to increase antigen cross-presentation for improving the clinical benefit of ICB in unfavorable patients.
Project description:To characterize the genetic basis of hybrid male sterility in detail, we used a systems genetics approach, integrating mapping of gene expression traits with sterility phenotypes and QTL. We measured genome-wide testis expression in 305 male F2s from a cross between wild-derived inbred strains of M. musculus musculus and M. m. domesticus. We identified several thousand cis- and trans-acting QTL contributing to expression variation (eQTL). Many trans eQTL cluster into eleven ‘hotspots,’ seven of which co-localize with QTL for sterility phenotypes identified in the cross. The number and clustering of trans eQTL - but not cis eQTL - were substantially lower when mapping was restricted to a ‘fertile’ subset of mice, providing evidence that trans eQTL hotspots are related to sterility. Functional annotation of transcripts with eQTL provides insights into the biological processes disrupted by sterility loci and guides prioritization of candidate genes. Using a conditional mapping approach, we identified eQTL dependent on interactions between loci, revealing a complex system of epistasis. Our results illuminate established patterns, including the role of the X chromosome in hybrid sterility.
Project description:CD8+ cytotoxic T cells are critical for viral clearance from the lungs upon influenza virus infection. The contribution of cross-presentation to the induction of anti-viral cytotoxic T cells remains debated. Here, we used a recombinant influenza virus expressing a NS1-GFP reporter gene to visualize the route of antigen presentation by lung dendritic cells (DC) upon viral infection in vivo. We found that lung CD103+ DC are the only subset to carry intact GFP protein to the draining lymph nodes. Strikingly, lung migratory CD103+ DC are not productively infected by influenza virus and thus induce virus-specific CD8+ T cells through the cross-presentation of antigens from virally infected cells. We also show that CD103+ DC resistance to infection correlates with an increased antiviral state in these cells that is dependent on the expression of IFN receptor alpha. In conclusion, these results establish that efficient cross-priming by migratory lung DC is coupled to the acquisition of an anti-viral status, which is dependent on type I IFN signaling pathway. mRNA profiles were generated by deep-sequencing in Illumina HiSeq2000 from alveolar macrophages and CD103+ dendritic cells from lungs of untreated and flu-treated mice
Project description:Introgressed variants from other species can be an important source of genetic variation because they may arise rapidly, can include multiple mutations on a single haplotype, and have often been pretested by selection in the species of origin. Although introgressed alleles are generally deleterious, several studies have reported introgression as the source of adaptive alleles-including the rodenticide-resistant variant of Vkorc1 that introgressed from Mus spretus into European populations of Mus musculus domesticus. Here, we conducted bidirectional genome scans to characterize introgressed regions into one wild population of M. spretus from Spain and three wild populations of M. m. domesticus from France, Germany, and Iran. Despite the fact that these species show considerable intrinsic postzygotic reproductive isolation, introgression was observed in all individuals, including in the M. musculus reference genome (GRCm38). Mus spretus individuals had a greater proportion of introgression compared with M. m. domesticus, and within M. m. domesticus, the proportion of introgression decreased with geographic distance from the area of sympatry. Introgression was observed on all autosomes for both species, but not on the X-chromosome in M. m. domesticus, consistent with known X-linked hybrid sterility and inviability genes that have been mapped to the M. spretus X-chromosome. Tract lengths were generally short with a few outliers of up to 2.7 Mb. Interestingly, the longest introgressed tracts were in olfactory receptor regions, and introgressed tracts were significantly enriched for olfactory receptor genes in both species, suggesting that introgression may be a source of functional novelty even between species with high barriers to gene flow.
Project description:Dendritic cell (DC)-mediated antigen presentation is essential for the priming and activation of tumor-specific T cells. However, few drugs that specifically manipulate DC functions are available. Here, we observed that DCs initiated a distinct transcriptional program during antigen presentation. We utilized a network-based approach to screen for DC-targeting therapeutics. Sitagliptin, an oral gliptin widely used for type 2 diabetes, was identified as a drug that targets DCs. In mouse models, sitagliptin inhibited tumor growth by enhancing DC-mediated antigen presentation, leading to better T cell activation.
Project description:Dendritic cell (DC)-mediated antigen presentation is essential for the priming and activation of tumor-specific T cells. However, few drugs that specifically manipulate DC functions are available. Here, we observed that DCs initiated a distinct transcriptional program during antigen presentation. We utilized a network-based approach to screen for DC-targeting therapeutics. Sitagliptin, an oral gliptin widely used for type 2 diabetes, was identified as a drug that targets DCs. In mouse models, sitagliptin inhibited tumor growth by enhancing DC-mediated antigen presentation, leading to better T cell activation.