Project description:The inhibitory axis of PD-1 expressed on T cells and its ligands produced by APCs mediates T cell exhaustion in chronic viral infection. We asked whether temporality of the infectious process is decisive for regulation through PD-1/PD-Ligand and investigated its impact on chronic bacterial infection. Here we show that M. tuberculosis and its lipid compounds induce expression of PD-Ligand on dendritic cells (DC). Upregulation of PD-Ligand depended on signaling through DC-SIGN upon infection. As a counterpart, expression of the PD-1 receptor was increased on T cells from tuberculosis patients and PPD+ donors compared to healthy normal individuals. Moreover, PD-1 expressing T cells were confined to granulomatous lesions in tuberculous lungs. Finally, functional blocking of PD-Ligand rescued antigen-specific T cell responses of tuberculosis patients. Taken together, we demonstrate that the inhibitory axis of PD-1/PD-Ligand is operative in mycobacterial infection and suggest inhibition of inhibition for rescuing exhausted T cells in tuberculosis. Keywords: Agilent two-color catolog 44K human whole genome microarrays
Project description:The inhibitory axis of PD-1 expressed on T cells and its ligands produced by APCs mediates T cell exhaustion in chronic viral infection. We asked whether temporality of the infectious process is decisive for regulation through PD-1/PD-Ligand and investigated its impact on chronic bacterial infection. Here we show that M. tuberculosis and its lipid compounds induce expression of PD-Ligand on dendritic cells (DC). Upregulation of PD-Ligand depended on signaling through DC-SIGN upon infection. As a counterpart, expression of the PD-1 receptor was increased on T cells from tuberculosis patients and PPD+ donors compared to healthy normal individuals. Moreover, PD-1 expressing T cells were confined to granulomatous lesions in tuberculous lungs. Finally, functional blocking of PD-Ligand rescued antigen-specific T cell responses of tuberculosis patients. Taken together, we demonstrate that the inhibitory axis of PD-1/PD-Ligand is operative in mycobacterial infection and suggest inhibition of inhibition for rescuing exhausted T cells in tuberculosis. Experiment Overall Design: Human PBMC-derived DCs were grown in 6-well plates and stimulated for 18 h with either mycobacterial ManLAM or recombinantly expressed ICAM-3. To ensure complete naïve status of DCs before stimulation, cells were left in wells from the day of PBMC isolation until end of stimulation. Change of medium was performed by carefully removing medium from wells without any manipulation of DCs. After stimulation, total RNA was isolated as described above and labeled with Fluorescent Direct Labeling Kit (Agilent Technologies) following manufacturerâs protocols. Microarray experiments were performed as two-color dye-reversal hybridizations. To compensate for dye-specific effects, a color swap was performed. Labeled RNA was hybridized on Whole Human Genome Oligo Microarray Kit 44k Format and scanned using an Agilent scanner according to manufacturerâs protocol (Agilent Technologies). Image analysis was performed using Feature Extractor software (Agilent Technologies). For data analysis Rosetta Resolver software was used (Rosetta Inpharmatics).
Project description:Rationale: T cell activation is a key antimicrobial component against mycobacterial disease. Programmed cell death-1 (PD-1) and programmed cell death-ligand 1 (PD-L1) pathway could affect the antimicrobial immune responses by suppressing T cell activity. Several recent studies demonstrated that blocking of PD-1/PD-L1 pathway exacerbated Mycobacterium tuberculosis infection. However, the influence of blocking this pathway in pulmonary Mycobacterium avium-intracellulare complex (MAC) infection was not fully understood. Objective: We aimed to determine the influence of genetic depletion of PD-1/PD-L1 pathway on the disease activity of MAC infection. Methods: Wild-type, PD-1-deficient mice and PD-L1-deficient mice were intranasally infected with Mycobacterium avium bacteria. Measurements and Main Results: The depletion of PD-1 or PD-L1 did not affect mortality and bacterial burden in mice infected with MAC. However, remarkable infiltration of CD8 T lymphocytes was observed in the lungs of PD-1 and PD-L1 deficient mice compared to wild-type mice. Comprehensive transcriptome analysis showed that levels of gene expressions related to Th1 immunity did not differ according to the genotypes. However, genes related to the activity of CD8 T cells and related chemokine activity were up-regulated in the infected lungs of PD-1 and PD-L1 deficient mice. Conclusions: Depletion of PD-1/PD-L1 pathway did not affect the activation of Th1 immunity in response to MAC infection, which may explain why MAC infection was controlled in these mice. In addition, CD8-positive T cell pulmonary inflammation in knockout mice might have some clinical implication in the treatment of cancer patients with immune checkpoint inhibitors when the patients are infected with MAC.
Project description:DC-SIGN is a C-type lectin expressed by dendritic cells (DCs) that binds HIV-1, sequestering it within multivesicular bodies to facilitate transmission to CD4+ T cells. Here we characterize the molecular basis of signalling through DC-SIGN by large-scale gene expression profiling and phosphoproteome analysis. Solitary DC-SIGN activation leads to a phenotypically disparate transcriptional program from Toll-like receptor (TLR) triggering with downregulation of MHC II, CD86, and interferon response genes and with induction of the TLR negative regulator ATF3. Phosphoproteome analysis reveals DC-SIGN signals through the leukemia-associated Rho guanine nucleotide exchange factor (LARG) to induce Rho activity. This LARG activation also occurs on DC HIV exposure and is required for effective HIV viral synapse formation. Taken together HIV mediated DC-SIGN signalling provides a mechanism by which HIV evades the immune response yet induces viral spread. Keywords: Activation state, signalling, Toll-like Receptor (TLR)
Project description:DC-SIGN is a C-type lectin expressed by dendritic cells (DCs) that binds HIV-1, sequestering it within multivesicular bodies to facilitate transmission to CD4+ T cells. Here we characterize the molecular basis of signalling through DC-SIGN by large-scale gene expression profiling and phosphoproteome analysis. Solitary DC-SIGN activation leads to a phenotypically disparate transcriptional program from Toll-like receptor (TLR) triggering with downregulation of MHC II, CD86, and interferon response genes and with induction of the TLR negative regulator ATF3. Phosphoproteome analysis reveals DC-SIGN signals through the leukemia-associated Rho guanine nucleotide exchange factor (LARG) to induce Rho activity. This LARG activation also occurs on DC HIV exposure and is required for effective HIV viral synapse formation. Taken together HIV mediated DC-SIGN signalling provides a mechanism by which HIV evades the immune response yet induces viral spread. Experiment Overall Design: Circulating monocyte derived DCs were isolated from buffy coats by adherence and culture in IL-4 and granulocyte-macrophage colony-stimulating factor (GM-CSF). DC preparations analyzed were more than 98% pure. At day four 10 million immature DCs were either left unstimulated or stimulated using plate bound anti-DC-SIGN antibody for 2 hr. Three replicates of non-stimulated or stimulated cells were taken and used to extract total RNA.
Project description:DC-SIGN+ monocyte-derived dendritic cells (mo-DCs) play important roles in bacterial infections and inflammatory diseases, but the factors regulating their differentiation and proinflammatory status remain poorly defined. Here, we identify a micro-RNA, miR-181a, and a molecular mechanism that simultaneously regulate the acquisition of DC-SIGN+ expression and the activation state of DC-SIGN+ mo-DCs. Specifically, we show that miR-181a promotes DC-SIGN expression during terminal mo-DC differentiation and limits its sensitivity and responsiveness to TLR triggering and CD40 ligation. Mechanistically, miR-181a sustains ERK-MAPK signaling in mo-DCs, thereby enabling the maintenance of high levels of DC-SIGN and a high activation threshold. Low miR-181a levels during mo-DC differentiation, induced by inflammatory signals, do not support the high phospho-ERK signal transduction required for DC-SIGNhi mo-DCs and lead to development of proinflammatory DC-SIGNlo/- mo-DCs. Collectively, our study demonstrates that high DC-SIGN expression levels and a high activation threshold in mo-DCs are linked and simultaneously maintained by miR-181a.
Project description:The present study reports the gene expression data of Mycobacterium tuberculosis H37Rv and H37RvΔdosSΔdosT (DKO) grown on 0.2 % acetate/glucose under aerobic/hypoxic conditions. Acetate was reported to be present in granulomas of Mycobacterium tuberculosis infected guinea pigs which are also hypoxic. By exposing Mycobacterium tuberculosis H37Rv and H37RvΔdosSΔdosT to different combinations of granulomatous stresses (acetate/glucose and aerobic/hypoxic conditions) alongwith other experimental data, we were able to delineate a new signaling pathway that activates DevR (DosR) regulon through Acetyl phosphate. The presence of two pathways highlights the importance of targeting DevR and not DevS/DosT for intercepting DevRST signalling cascade.
Project description:RpfB is one of five resuscitation promoting factors in Mycobacterium tuberculosis. We previously published data indicating the 5' UTR of the gene contains a regulatory riboswitch with an unknown (at the time) ligand. We overexpressed the switch in Mycobacterium smegmatis (which does not contain the rpfB gene), reasoning that overexpression of the switch would s sequester the unknown ligand, giving rise to a phenotype that would help us identify it.
Project description:We engineered a glycan-costumed virus-like particle (VLP) vaccine that delivers programmable peptide antigens to induce tumor-specific cellular immunity in vivo. VLPs encapsulating TLR7 agonists were decorated with a synthetic mannose-derived ligand (VLP-Man-OvaI/II) that selectively engages the lectin DC-SIGN. Lectin-TLR7 dual engagement induced robust DC activation and type 1 cellular immunity, whereas VLPs lacking this key DC-SIGN ligand (VLP-PE-OvaI/II) failed to promote DC-mediated cellular responses. We performed bulk RNA-seq experiments on moDCs treated with VLP-Man-OvaI/II and VLP-PE-OvaI/II or unstimulated control moDCs. A total of 486 genes were differentially expressed after treatment with VLP-Man-OvaI/II vs. VLP-PE-OvaI/II (log2FC >1.5 and p<0.05). The significantly upregulated genes included CXCL1, CXCL5, ISG15, IL6, CCL4, ISG20, and SOCS3, all of which are implicated in the TLR7 downstream signaling pathway, suggesting a higher extent of TLR7 activation with the VLP-Man-OvaI/II. Gene set enrichment analysis (GSEA) between VLP-Man-OvaI/II- and VLP-PE-OvaI/II-treated moDCs revealed that hallmark DC activation pathways were also upregulated in VLP-Man-OvaI/II-treated DCs, including pathways related to IFN-a, IFN-g, and TNF-a signaling via nuclear factor-κB (NF-kB). These data give insight into how lectin binding with glycan-costumed VLPs can be employed to reprogram immunity.
Project description:This project involves RNA-Seq analysis of samples obtained from the Phase IIA clinical trial TB-019 (NCT01669096) which evaluated kinetics of response, safety, and immunogenicity of the GSK Mycobacterium tuberculosis (MTB) vaccine M72/AS01E (“GSK M72”). GSK M72 consists of the M72 recombinant fusion of Mycobacterium tuberculosis (MTB) proteins Rv0125 and Rv1196 in combination with the liposome, TLR4 ligand (MPL), and QS21 saponin adjuvant AS01E (Leroux-Roels et al., 2013).