Project description:We want to define the differences in gene expression changes between neonatal and adult plasmacytoid dendritic cells upon stimulation with TLR7/8. These differences may point to specific signaling pathways which, in turn, may account for the known differential immune response of babies to vaccination or infection when compared to adults.
Project description:Previous studies have shown that purified dendritic cells (DCs) have cell-intrinsic, age-dependent differences in their response to TLR stimulation. To delineate which aspects of the age-dependent difference in innate immunity are cell intrinsic vs extrinsic, we searched for global differences to TLR7/8 stimulation in purified adult vs neonatal DC populations. We hypothesize that very few selected cell intrinsic differences in gene expression of key immune genes between these 2 age groups exist, and the bulk would be cell extrinsic differences. The results show that there are age-dependent differences in expression of several key genes involved in the immune response at baseline already. Upon stimulation, we identified a substantially larger fraction of age-dependent differentially expressed genes in conventional than plasmacytoid DCs. Bioinformatics analyses indicate that important immune pathways were significantly differentially expressed in DC subsets between the 2 age groups. Total RNA was isolated from purified human conventional and plasmacytoid dendritic cells from 6 adult and 6 cord blood donors that were stimulated with 3M-003 at a final concentration of 5 uM for 1 and 6 hr.
Project description:Plasmacytoid dendritic cells (pDC) efficiently produce large amounts of type I interferon in response to TLR7 and TLR9 ligands, whereas conventional DCs (cDC) predominantly secrete high levels of the cytokines IL-10 and IL-12. The molecular basis underlying this distinct phenotype is not well understood. Here, we identified the MAPK phosphatase Dusp9/MKP-4 by transcriptome analysis as selectively expressed in pDC, but not cDC. We confirmed the constitutive expression of Dusp9 at the protein level in pDC generated in vitro by culture with Flt3L and ex vivo in sorted splenic pDC. Dusp9 expression was low in B220- bone marrow precursors and was up-regulated during pDC differentiation, concomitant with established pDC markers. Higher expression of Dusp9 in pDC correlated with impaired phosphorylation of the MAPK ERK1/2 upon TLR9 stimulation. Notably, Dusp9 was not expressed at detectable levels in human pDC, although these displayed similarly impaired activation of ERK1/2 MAPK compared to cDC. Enforced retroviral expression of Dusp9 in mouse GM-CSF-induced cDC increased the expression of TLR7/9-induced IL-12p40 and IFNwhereas IL-10 levels were diminished. Taken together, our results suggest that the species-specific, selective expression of Dusp9 in murine pDC contributes to the differential cytokine/interferon output of pDC and cDC. pDC and cDC subsets were purified from mouse spleens to high purity and analysed by Affymetrix GeneChips.
Project description:We want to define the differences in gene expression changes between neonatal and adult myeloid dendritic cells upon stimulation with TLR7/8. These differences may point to specific signaling pathways which, in turn, may account for the known differential immune response of babies to vaccination or infection when compared to adults.
Project description:Plasmacytoid dendritic cells (pDC) efficiently produce large amounts of type I interferon in response to TLR7 and TLR9 ligands, whereas conventional DCs (cDC) predominantly secrete high levels of the cytokines IL-10 and IL-12. The molecular basis underlying this distinct phenotype is not well understood. Here, we identified the MAPK phosphatase Dusp9/MKP-4 by transcriptome analysis as selectively expressed in pDC, but not cDC. We confirmed the constitutive expression of Dusp9 at the protein level in pDC generated in vitro by culture with Flt3L and ex vivo in sorted splenic pDC. Dusp9 expression was low in B220- bone marrow precursors and was up-regulated during pDC differentiation, concomitant with established pDC markers. Higher expression of Dusp9 in pDC correlated with impaired phosphorylation of the MAPK ERK1/2 upon TLR9 stimulation. Notably, Dusp9 was not expressed at detectable levels in human pDC, although these displayed similarly impaired activation of ERK1/2 MAPK compared to cDC. Enforced retroviral expression of Dusp9 in mouse GM-CSF-induced cDC increased the expression of TLR7/9-induced IL-12p40 and IFNwhereas IL-10 levels were diminished. Taken together, our results suggest that the species-specific, selective expression of Dusp9 in murine pDC contributes to the differential cytokine/interferon output of pDC and cDC.
Project description:The healthy intestine mounts immune responses to microbiota to maintain homeostasis, which includes basal production of interferon cytokines. Previous work showed that Type III Interferon (IFN-λ) stimulates localized pockets of interferon-stimulated genes (ISGs) in the adult mouse intestinal epithelium at homeostasis that provide preemptive protection from viral pathogens. Here, we demonstrate that a major source of homeostatic IFN-λ production in the intestine is a population of epithelium-associated plasmacytoid dendritic cells (pDC). These pDC are recruited to the intestine by bacterial microbiota colonization, and pDC depletion or bone marrow reconstitution with IFN-λ-deficient pDC results in reduced homeostatic ISGs in the intestinal epithelium. Notably, intestinal pDC preferentially produce IFN-λ over Type I IFNs whereas splenic pDC produce more Type I IFNs. Comparison of splenic and intestinal pDC reveal tissue-specific changes in gene expression and genomic accessibility, including evidence of response to transforming growth factor beta (TGF-β) in the intestine. Isolated gut pDC produce more IFN-λ that splenic pDC upon stimulation, and pre-treatment of a human pDC cell line with TGF-β results in enhanced production of IFN-λ upon stimulation. This study implicates pDC as important sources of homeostatic IFN-λ in the intestine and defines the role of barrier cytokine TGF-β in regulating IFN types produced by pDC upon stimulation. Reprogramming of recruited pDC by tissue cytokines may have important implications for balancing effective antimicrobial responses with damaging inflammation at barrier tissues.
Project description:The healthy intestine mounts immune responses to microbiota to maintain homeostasis, which includes basal production of interferon cytokines. Previous work showed that Type III Interferon (IFN-λ) stimulates localized pockets of interferon-stimulated genes (ISGs) in the adult mouse intestinal epithelium at homeostasis that provide preemptive protection from viral pathogens. Here, we demonstrate that a major source of homeostatic IFN-λ production in the intestine is a population of epithelium-associated plasmacytoid dendritic cells (pDC). These pDC are recruited to the intestine by bacterial microbiota colonization, and pDC depletion or bone marrow reconstitution with IFN-λ-deficient pDC results in reduced homeostatic ISGs in the intestinal epithelium. Notably, intestinal pDC preferentially produce IFN-λ over Type I IFNs whereas splenic pDC produce more Type I IFNs. Comparison of splenic and intestinal pDC reveal tissue-specific changes in gene expression and genomic accessibility, including evidence of response to transforming growth factor beta (TGF-β) in the intestine. Isolated gut pDC produce more IFN-λ that splenic pDC upon stimulation, and pre-treatment of a human pDC cell line with TGF-β results in enhanced production of IFN-λ upon stimulation. This study implicates pDC as important sources of homeostatic IFN-λ in the intestine and defines the role of barrier cytokine TGF-β in regulating IFN types produced by pDC upon stimulation. Reprogramming of recruited pDC by tissue cytokines may have important implications for balancing effective antimicrobial responses with damaging inflammation at barrier tissues.
Project description:Previous studies have shown that purified dendritic cells (DCs) have cell-intrinsic, age-dependent differences in their response to TLR stimulation. To delineate which aspects of the age-dependent difference in innate immunity are cell intrinsic vs extrinsic, we searched for global differences to TLR7/8 stimulation in purified adult vs neonatal DC populations. We hypothesize that very few selected cell intrinsic differences in gene expression of key immune genes between these 2 age groups exist, and the bulk would be cell extrinsic differences. The results show that there are age-dependent differences in expression of several key genes involved in the immune response at baseline already. Upon stimulation, we identified a substantially larger fraction of age-dependent differentially expressed genes in conventional than plasmacytoid DCs. Bioinformatics analyses indicate that important immune pathways were significantly differentially expressed in DC subsets between the 2 age groups.
Project description:Plasmacytoid dendritic cells (pDCs) can be activated by the endosomal TLRs, and contribute to the pathogenesis of systemic lupus erythematosus (SLE) by producing type I IFNs. Thus, blocking TLR-mediated pDC activation may represent a useful approach for the treatment of SLE. In an attempt to identify a therapeutic target for blocking TLR signaling in pDCs, we investigated the contribution of Bruton's tyrosine kinase (Btk) to the activation of pDCs by TLR7 and TLR9 stimulation by using a selective Btk inhibitor RN486. Stimulation of TLR7 and 9 with their respective agonist, namely, gardiquimod and type A CpG ODN2216, resulted in the activation of human pDCs, as demonstrated by the expression of activation markers (CD69, CD40, and CD86), elevated production of IFN-alpha and other inflammatory cytokines, as well as up-regulation of numerous genes including IFN-alpha-inducible genes and activation of interferon regulatory factor 7 (IRF7) and NF-kB. RN486 inhibited all of these events induced by TLR9, but not TLR7 stimulation, with a nanomolar potency for inhibiting type A CpG ODN2216-mediated production of cytokines (e.g., IC50=386 nM for inhibiting IFN-alpha). Our data reveal Btk as an important regulatory enzyme in the TLR9 pathway, and a potential therapeutic target for SLE and other TLR-driven diseases. pDCs from healthy donors (n=4) were treated with gardiquimod (TLR7 agonist) or ODN 2216 (TLR9 agonist) with or without BTK inhibitor for 3 hours.