Project description:we studied the role of exosomes isolated from M.tb infected macrophages in modulating the macrophage response to IFN-γ. Nimblegen microarray gene expression studies were used to compare the suppression of IFN-γ inducible genes by exosomes relative to the virulent strain of M.tuberculosis. Overall our study suggest that exosomes, as carriers of M.tb pathogen associated molecular patterns (PAMPs), may provide a mechanistic link by which M.tb may exert its suppression of host immune response beyond the infected cell, and implies a physiological role for exosomes in immune surveillance of TB. Macrophages were treated with exosomes, infected with M.tb H37Rv or left untreated for 18 hours followed by +/- IFN-γ for an additional 18 hours. Cells were harvested and RNA was isolated and converted to double stranded cDNA and subsequently labeled and hybridized onto Mus musculus 4×72 Nimblegen microarray using Nimblegen Hybridization system 4 according to manufacturer’s instructions (Roche)
Project description:we studied the role of exosomes isolated from M.tb infected macrophages in modulating the macrophage response to IFN-γ. Nimblegen microarray gene expression studies were used to compare the suppression of IFN-γ inducible genes by exosomes relative to the virulent strain of M.tuberculosis. Overall our study suggest that exosomes, as carriers of M.tb pathogen associated molecular patterns (PAMPs), may provide a mechanistic link by which M.tb may exert its suppression of host immune response beyond the infected cell, and implies a physiological role for exosomes in immune surveillance of TB.
Project description:Mycobacterial transcripts were identified in exosomes released from M.tb infected RAW264.7 macrophages that were not present in uninfected exosomes suggesting export of mycobacterial RNA via exosomes Mycobacterial RNA was used as positive control and RNA from exosomes released from uninfected macrophages was used as negative control
Project description:Macrophages are major effector cells and antigen presenting cells of the innate immune system and classical activation of macrophage function requires interferon–γ (IFN-γ) pretreatment (priming) and TLR stimuli, which promotes inflammatory responses though high levels of pro-inflammatory cytokines and lower level of the anti-inflammatory cytokines, resulting in microbicidal and tumoricidal effect. However, the underlying molecular mechanism of IFN-γ priming remains elusive. In this study, we explored the effect of IFN-γ on macrophages at miRNA level and discovered that miR-3473b, which was down-regulated after IFN-γ priming, could attenuate the priming effect of IFN-γ. Molecular study revealed that miR-3473b promoted Akt/GSK3 signaling and IL-10 production through directly targeting PTEN to suppress inflammatory response and tumor-suppressing capability of macrophages. In summary, our data demonstrate that IFN-γ beef up macrophage inflammatory response and tumor suppressing capacity by limiting miR-3473b-mediated PTEN suppression. Our work identified an IFN-γ/miR-3473b/Akt axis in the regulation of macrophage function and activation. the assay was performed with 5 μg total RNA samples from both normal BMM (labeled by Cy3) and BMM primed by IFN-γ (100U/ml) for 4 h(labeled by Cy5), normal BMM serves as control.
Project description:Investigation to study mRNA transcripts present in exosomes from M.tb infected cells and how they compare to those derived from uninfected cells. Transcripts were also studied in donor macrophages as controls The gene expression study identified unique transcripts as well as differentially expressed transcripts present in exosomes released from infected macrophages
Project description:Gene expression analysis of freshly isolated CD14+ human monocytes and monocytes cultured in the presence or absence of interferon (IFN) -gamma for 24 h and then stimulated with Pam3Cys, a Toll-like receptor (TLR) 2 ligand, for 6 h. Results provide insight into mechanisms by which IFN-gamma reprograms early macrophage differentiation and subsequent response to TLR ligands.
Project description:The immune response against tuberculosis relies, at least in part, on CD4+ T cells. Protective vaccines require the induction of antigen-specific CD4+ T cells via mycobacterial peptides presented by MHC class-II in infected macrophages. We have purified MHC class-I and MHC-II peptides and analysed them by mass spectrometry. We have successfully identified 97 mycobacterial peptides presented by MHC-II and 54 presented by MHC-I, from 76 and 41 antigens, respectively. The sequences of selected peptides were confirmed by spectral match validation and immunogenicity evaluated by IFN-gamma ELISpot against peripheral blood mononuclear cells from volunteers vaccinated with BCG, M.tb latently infected subjects or patients with tuberculosis disease. Three antigens were expressed in viral vectors, and evaluated as vaccine candidates alone or in combination in a murine aerosol M.tb challenge model. When delivered in combination, the three candidate vaccines conferred significant protection in the lungs and spleen compared with BCG alone, demonstrating proof-of-concept for this unbiased approach to identifying novel candidate antigens.
Project description:Macrophages are known to be polarized into inflammatory (M1) and immunoregulatory (M2) cells when they are stimulated by agonists such as IFN-gamma and IL-4, respectively. If circulating monocytes may be polarized in response to T cell signals is often misguidedly deduced from macrophage results. Here the transcriptional responses of human CD14+ monocytes to IFN-gamma and IL-4 were analyzed using whole genome microarrays. A principal component analysis and hierarchical clustering showed that monocyte and macrophage responses were distinct. Monocytes stimulated with IFN-gamma and IL-4 for 6 hours exhibited some features of macrophage polarization. Indeed, when 80 genes considered as M1 and M2 genes were analyzed, we found that M1 genes were modulated in response to IFN-gamma and that M2 genes were modulated in response to IL-4. The M1 polarization of monocytes was transient because only M2 genes were modulated when monocytes were stimulated with IFN-gamma and IL-4 for 18 hours. However, the activation of monocytes by IFN-gamma and IL-4 could not be reduced to M1/M2 polarization status. Indeed, monocytes exhibited early specific signatures composed of 46 and 39 up-regulated genes in response to IFN-gamma and IL-4, respectively, and a late signature common to both molecules that consisted of 57 up-regulated genes. Taken together, these results demonstrated the extreme plasticity of human monocytes and suggested the existence of a core transcriptional termination program. Using early and late signatures might be pertinent to investigate monocyte activation in inflammatory or infectious diseases. Monocytes were stimulated with IFN-gamma (20ng/mL) or IL-4 (20ng/mL) for 6 and 18 hours or culture for 6 and 18 hours without agonist (Unstimulated samples). Monocytes-derived-macrophages (MDM) stimulated with IFN-gamma and IL-4 for 18 hours were used as controls. Each microarray is derived from a single biological sample.
Project description:To investigate the early host response triggered by three different strains of Trypanosoma cruzi at a local infection site, changes in host gene expression were monitored in a murine intradermal infection model using Affymetrix oligonucleotide arrays. Robust induction of IFN-stimulated genes (ISGs) was observed in excised skin 24 hours post-infection where the level of ISG induction was parasite strain-dependent with the least virulent strain triggering a muted IFN response. Infection of mice immunodepleted of IFNγ-producing cells or infection of IFNγ-deficient mice had minimal impact on the IFN response generated in T. cruzi infected mice. In contrast, infection of mice lacking the type I IFN receptor demonstrated that type I IFNs are largely responsible for the IFN response generated at the site of infection. These data highlight type I IFNs as important components of the innate immune response to T. cruzi the site of inoculation and their role in shaping the early transcriptional response to this pathogen. We used microarrays to detail the local host transcriptional response to intradermal T. cruzi infection in WT mice and mice depleted of NK cells, or deficient in IFN-gamma or type I IFN responses. Additionally we compared the local host-transcriptional response generated to infection with 3 different strains of Trypanosoma cruzi (Y, Brazil, and G). Experiment Overall Design: Mice were infected by intradermal injection of 10^6 T. cruzi trypomastigotes in 100uL of saline split between 2 adjacent sites on the shaved side flank. Control mice were injected with an equal volume of saline. 24 hours post-injection approximately 75mm^2 of skin immediately surrounding the injection site was excised and RNA was isolated from the tissue. Balb/c mice were used for most experiments and IFN-gamma KO mice were on the Balb/c background. WT 129 mice were also used as IFNAR-/- mice were on the 129 background. In total 33 arrays were performed. 7 WT (Balb/c) control, 3 Y strain infected, 3 Brazil strain infected, 3 G strain infected, 2 IFN-gamma KO control, 2 IFN-gamma KO infected, 1 NK cell depleted control, 1 NK cell depleted infected, 3 WT (129) control, 3 WT (129) infected, 3 IFNAR KO control, 3 IFNAR KO infected