Distinct SARS-CoV-2 sensing pathways in pDCs driving TLR7-antiviral vs. TLR2-immunopathological responses in COVID-19
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PROVIDER: PRJNA802559 | ENA |
REPOSITORIES: ENA
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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.
2015-10-24 | E-GEOD-41825 | biostudies-arrayexpress
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.
2015-10-24 | GSE41825 | GEO
Project description:In this study, we broadly investigated the nature and timing of SARS-CoV-2-induced changes in pDC gene expression, therefore we profiled 789 selected genes using NanoString nCounter technology after 4, 24 and 48 hrs in two individual donors found to be high (Dhigh) and low (Dlow) responders in terms of IFN production
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Project description:The purpose of this experiment was to assess the genes upregulated when pDCs were stimulated with TLR7 agonist imiquimod and TLR9 agonist CpG C. pDCs were isolated from six healthy donors by FACS sorting, and were stimulated with CpG and imiquimod for 18 hours, after which RNA was extracted for next generation sequencing on the Illumina HiSeq platform. Unstimulated samples were included as controls.
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Project description:The purpose of this experiment was to assess the genes upregulated when pDCs were stimulated with TLR7 agonist imiquimod and TLR9 agonist CpG C.
2016-03-17 | GSE79272 | GEO
Project description:Toll-like receptor 7 (TLR7) plays a key role in the recognition of RNA viruses and the subsequent induction of an innate immune response. TLR7 contains two ligand binding pockets that recognize distinct RNA degradation products: Pocket 1 recognizes guanosine nucleotides and pocket 2 coordinates short, pyrimidine-rich RNA fragments, while the engagement of both pockets is required to activate TLR7. How these ligands are generated within the endolysosomal compartment is currently unknown. Using a pDC cell line, we here show that the endonuclease RNase T2 and the 5' exonucleases PLD3 and PLD4 act in concert to produce these ligands. On the one hand, RNase T2 generates 2',3'-cyclophosphate-guanosine terminated RNA fragments upon which PLD exonuclease activity acts to release the terminal 2',3'-cyclic GMP. This molecule serves as the physiological ligand for the first binding pocket. On the other hand, PLD activity is also required to generate short RNA fragments that occupy the second binding pocket of TLR7. While PLD3 and PLD4 exert comparable catalytic activities, the almost exclusive expression of PLD4 in pDCs suggests that PLD4 is the relevant exonuclease for pDC activation in the human system. Biochemical and structural studies of PLD3 and PLD4 show that these enzymes form homodimers with two ligand binding sites. Dimer formation is critical for catalytic activity, and previously identified disease-associated mutants fail to form stable dimers. In conclusion, our data provide a mechanistic basis for the recognition of RNA fragments by TLR7.
2024-06-19 | PXD045912 | Pride
Project description:Plasmacytoid dendritic cells (pDCs) are a rare type of dendritic cells that exist antiviral functions in response to toll-like receptors (TLRs). We here report TLR4 activated pDCs similar to TLR7/8 stimulation. Despite the high resemblance, we found the unique genes that were activated by TLR4 activation.
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Project description:Type I interferons (IFN-I) are important mediators of antiviral immunity and autoimmune diseases. Plasmacytoid dendritic cells (pDCs) from females exert an elevated capacity to produce IFN-I in response to activation of toll-like receptor 7 (TLR7) compared to male pDCs, and both hormones and genes encoded by the X chromosome have been implicated in these sex-specific differences. Using longitudinal samples collected from a cohort of trans men receiving testosterone injections as gender-affirming hormone therapy (GAHT), the impact of testosterone on TLR7-mediated IFN-I production by pDCs was assessed. GAHT induced testosterone and estradiol levels within male reference ranges and increased hemoglobin and hematocrit levels, demonstrating biological activity of testosterone. scRNA seq of pDCs showed downregulation of IFN-I-related gene expression signatures, but also revealed inter-donor heterogeneity on the transcriptional level. Longitudinal quantification of IFN-I protein production by pDCs following TLR7-stimulation showed significant and continuous reduction of IFN-I production in trans men, and reduced expression of IFN-I-stimulated genes. These longitudinal studies in trans men demonstrate that testosterone can reduce IFN-I production by pDCs, and provide novel insights into the immune-modulatory role of testosterone in sex differential IFN-I-mediated immune responses.
2023-11-09 | GSE231370 | GEO
Project description:Understanding the molecular pathways driving the acute antiviral and inflammatory response to SARS-CoV-2 infection is critical for developing treatments for severe COVID-19. Here, we find decreasing number of circulating plasmacytoid dendritic cells (pDCs) in COVID-19 patients early after symptom onset, correlating with disease severity. pDC depletion is transient and coincides with decreased expression of antiviral type I IFNα and of systemic inflammatory cytokines CXCL10 and IL-6. Using an in vitro stem cell-based human pDC model, we further demonstrate that pDCs, while not supporting SARS-CoV-2 replication, directly sense the virus and in response produce multiple antiviral (interferons: IFNα and IFNλ1) and inflammatory (IL-6, IL-8, CXCL10) cytokines that protect epithelial cells from de novo SARS-CoV-2 infection. Via targeted deletion of virus-recognition innate immune pathways, we identify TLR7-MyD88 signaling as crucial for production of antiviral interferons, whereas TLR2 is responsible for the inflammatory IL-6 response. We further show that SARS-CoV-2 engages the receptor neuropilin-1 on pDCs to selectively mitigate the antiviral interferon response, but not the IL-6 response, suggesting neuropilin-1 as potential therapeutic target for stimulation of TLR7-mediated antiviral protection.
| S-SCDT-EMBOJ-2021-109622 | biostudies-other
Project description:Understanding the molecular pathways driving the acute antiviral and inflammatory response to SARS-CoV-2 infection is critical for developing treatments for severe COVID-19. Here, we find decreasing number of circulating plasmacytoid dendritic cells (pDCs) in COVID-19 patients early after symptom onset, correlating with disease severity. pDC depletion is transient and coincides with decreased expression of antiviral type I IFNα and of systemic inflammatory cytokines CXCL10 and IL-6. Using an in vitro stem cell-based human pDC model, we further demonstrate that pDCs, while not supporting SARS-CoV-2 replication, directly sense the virus and in response produce multiple antiviral (interferons: IFNα and IFNλ1) and inflammatory (IL-6, IL-8, CXCL10) cytokines that protect epithelial cells from de novo SARS-CoV-2 infection. Via targeted deletion of virus-recognition innate immune pathways, we identify TLR7-MyD88 signaling as crucial for production of antiviral interferons (IFNs), whereas Toll-like receptor (TLR)2 is responsible for the inflammatory IL-6 response. We further show that SARS-CoV-2 engages the receptor neuropilin-1 on pDCs to selectively mitigate the antiviral interferon response, but not the IL-6 response, suggesting neuropilin-1 as potential therapeutic target for stimulation of TLR7-mediated antiviral protection.
| S-EPMC9108609 | biostudies-literature