Type I and II interferons enhance dendritic cell maturation and migration capacity by regulating CD38 and CD74 that have synergistic effects with TLR agonists.
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ABSTRACT:
SUBMITTER: Nguyen-Pham TN
PROVIDER: S-EPMC4002448 | biostudies-other | 2011 Jul
REPOSITORIES: biostudies-other
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Project description:Toll like receptors (TLRs) sense microbial products and initiate adaptive immune responses by activating dendritic cells (DCs). Since pathogens may contain several agonists we asked whether different TLRs may synergize in DC activation. We report that in human and mouse DC TLR3 or TLR4 potently synergize with TLR7, TLR8 or TLR9 in the induction of selected cytokine genes. Upon synergistic stimulation, IL-12, IL-23 and Delta-4 are induced at levels 50-100 fold higher than those induced by optimal concentrations of single agonists, leading to enhanced and sustained TH1 polarizing capacity. Using microarray analysis we show that only 1.5% of the transcripts induced by single TLR agonists are synergistically regulated by combinations of TLR4 and TLR8 agonists.. These results identify a combinatorial code by which DCs discriminate pathogens and provide (suggest) a rationale to design adjuvants for TH1 responses. Series_overall_design: 3 untreated, 3 treated with LPS at 2h, 3 treated with LPS at 8h, 3 treated with R848 at 2h, 3 treated with R848 at 8h, 3 treated with LPS + R848 at 2h, 3 treated with LPS + R848 at 8h Keywords: other
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Project description:Peptide loading of MHC class II (MHCII) molecules is catalyzed by the nonclassical MHCII-related molecule H2-M. H2-O, another MHCII-like molecule, associates with H2-M and modulates H2-M function. The MHCII presentation pathway is tightly regulated in dendritic cells (DCs), yet how the key modulators of MHCII presentation, H2-M and H2-O, are affected in different DC subsets in response to maturation is unknown. In this study, we show that H2-O is markedly downregulated in vivo in mouse CD8?(-) DCs in response to a broad array of TLR agonists. In contrast, CD8?(+) DCs only modestly downregulated H2-O in response to TLR agonists. H2-M levels were slightly downmodulated in both CD8?(-) and CD8?(+) DCs. As a consequence, H2-M/H2-O ratios significantly increased for CD8?(-) but not for CD8?(+) DCs. The TLR-mediated downregulation was DC specific, as B cells did not show significant H2-O and H2-M downregulation. TLR4 signaling was required to mediate DC H2-O downregulation in response to LPS. Finally, our studies showed that the mechanism of H2-O downregulation was likely due to direct protein degradation of H2-O as well as downregulation of H2-O mRNA levels. The differential H2-O and H2-M modulation after DC maturation supports the proposed roles of CD8?(-) DCs in initiating CD4-restricted immune responses by optimal MHCII presentation and of CD8?(+) DCs in promoting immune tolerance via presentation of low levels of MHCII-peptide.
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Project description:BackgroundPlasmacytoid Dendritic Cells (pDC) comprise approximately 0.2 to 0.8% of the blood mononuclear cells and are the primary type 1 interferon (IFN), producing cells, secreting high levels of IFN in response to viral infections. Plasmacytoid dendritic cells express predominantly TLRs 7 & 9, making them responsive to ssRNA and CpG DNA. The objective of this study was to evaluate the molecular and cellular processes altered upon stimulation of pDC with synthetic TLR 7 and TLR 7/8 agonists. To this end, we evaluated changes in global gene expression upon stimulation of 99.9% pure human pDC with the TLR7 selective agonists 3M-852A, and the TLR7/8 agonist 3M-011.ResultsGlobal gene expression was evaluated using the Affymetrix U133A GeneChip(R) and selected genes were confirmed using real time TaqMan(R) RTPCR. The gene expression profiles of the two agonists were similar indicating that changes in gene expression were solely due to stimulation through TLR7. Type 1 interferons were among the highest induced genes and included IFNB and multiple IFNalpha subtypes, IFNalpha2, alpha5, alpha6, alpha8, alpha1/13, alpha10, alpha14, alpha16, alpha17, alpha21. A large number of chemokines and co-stimulatory molecules as well as the chemokine receptor CCR7 were increased in expression indicating maturation and change in the migratory ability of pDC. Induction of an antiviral state was shown by the expression of several IFN-inducible genes with known anti-viral activity. Further analysis of the data using the pathway analysis tool MetaCore gave insight into molecular and cellular processes impacted. The analysis revealed transcription networks that show increased expression of signaling components in TLR7 and TLR3 pathways, and the cytosolic anti-viral pathway regulated by RIG1 and MDA5, suggestive of optimization of an antiviral state targeted towards RNA viruses. The analysis also revealed increased expression of a network of genes important for protein ISGylation as well as an anti-apoptotic and pro-survival gene expression program.ConclusionThus this study demonstrates that as early as 4 hr post stimulation, synthetic TLR7 agonists induce a complex transcription network responsible for activating pDC for innate anti-viral immune responses with optimized responses towards RNA viruses, increased co-stimulatory capacity, and increased survival.
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Project description:Therapies based on Toll Like Receptor agonists (TLRa) are emerging as a promising modality for cancer immunotherapy to recruit antitumor T-cells in unresponsive immunologically "cold" tumors. Often, combinations of agonists are employed to synergistically enhance efficacy. However, low efficacy and severe toxicities deter these TLR-based therapeutics from further clinical applications. Studies have suggested that the rapid systemic diffusion of agonists to nontarget tissues is the primary cause. To address this challenge, we developed supramolecular nanotherapeutics of covalently linked TLRas for multivalent, synergistic interactions by drawing inspiration from immune recognition of pathogens. This new nanotherapeutic increased stimulation of key pro-inflammatory cytokines and remarkably enhanced CD8 and NK cell-mediated antitumor response while exhibiting ultralow off-target toxicity in an aggressive B16.F10 tumor model. Results from our studies thereby indicate that such supramolecular immune-agonist therapeutics may be further developed as a viable treatment modality for cancer immunotherapy.
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Project description:HLA-B*57 affects the course of HIV infection. Under antiretroviral therapy, its effects cannot be explained by outstandingly efficient T cell responses alone but may also involve cells of innate immunity. Studying in vitro stimulation with Pam3CSK4, E. coli LPS-B5 and CpG-ODN-2216, we observed greater induction of IL-6/IL-1beta double-positive CD14+CD16++ monocytes as well as IFN-gamma-positive cytotoxic CD56highCD16neg NK cells in HLA-B*57- versus HLA-B*44-positive HIV patients, while TNF-alpha induction remained unchanged. Differences were not seen in the other monocyte and NK cell subsets or in HLA-matched healthy controls. Our findings show that, in virally suppressed HIV infection, HLA-B*57 is associated with enhanced responsiveness of inflammatory innate immune cells to TLR ligands, possibly contributing to increased vulnerability in sepsis. KEY MESSAGES: • HLA-B*57 is a host factor affecting clinical outcomes of HIV infection. • HLA-B*57 modifies inflammatory subsets of NK cells and monocytes in HIV infection. • In HLA-B*57-positive HIV patients TLR agonists induce enhanced IL-6/IL-1beta in monocytes. • NK cells from HLA-B*57 HIV patients release more IFN-gamma upon TLR costimulation. • HLA-B*57 is linked to enhanced inflammatory responsiveness to TLR ligands.
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Project description:Various TLR agonists are currently under investigation in clinical trials for their ability to orchestrate antitumor immunity. The antitumor responses are largely attributed to their aptitude to stimulate APCs such as DCs which in turn, activate tumor-specific T cell responses. However, there is a potential for TLR signaling to occur on cells other than professional APCs that could negate antitumor responses or even worse, promote tumor growth. The impetus for this review is twofold. First, there is accumulating data demonstrating that the engagement of TLRs on different T cell subsets and different cancer types could promote tumor growth or conversely, contribute to antitumor responses. Second, the efficacy of TLR agonists as monotherapies to treat cancer patients has been limited. In this review, we discuss how TLR signaling within different T cell subsets and cancer cells can potentially impact the generation of antitumor responses. Based on evidence from preclinical models and clinical trials, we draw attention to several criteria that we believe must be considered when selecting TLR agonists for developing effective immunotherapeutic strategies against cancer.
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