Antigen-specific CD4+ T cells promote monocyte recruitment and differentiation into glycolytic lung macrophages to control Mycobacterium tuberculosis.
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ABSTRACT: Although lung myeloid cells provide an intracellular niche for Mycobacterium tuberculosis (Mtb), CD4+ T cells limit Mtb growth in these cells to protect the host. Here, we show that monocyte-derived macrophages (MDMs), instead of phenotypically similar dendritic cells, are preferentially infected with Mtb in murine lungs. Mtb-specific CD4+ T cells recruited monocyte precursors of MDMs into the lungs via interferon-γ (IFN-γ). Although the CD4+ T cells increased the number of Mtb-infectable cells in the lungs, they then attenuated Mtb growth by engaging in MHC class II (MHCII)-mediated cognate interactions with monocyte-derived cells to promote their disinfection. Specifically, cognate CD4+ T cell help via MHCII enhanced MDM expression of glycolytic genes independently of IFN-γ. These results indicate that CD4+ T cells recruit infectable MDMs to the lungs and trigger glycolysis-dependent bacterial control within them by engaging MHCII-bound Mtb peptides on their surfaces.
Project description:Alveolar macrophages (AMs) and recruited monocyte-derived macrophages (MDMs) mediate early lung immune responses to Mycobacterium tuberculosis (Mtb). Using paired human AMs and MDMs from 6 healthy volunteers, we investigated transcriptional profiles in responses to Mtb. We found 681 genes that were Mtb-dependent in AMs compared to MDMs, 107 that were induced in both cell types but in different directions, and 4538 that were Mtb-dependent in MDMs but not AMs (FDR < 0.05). We found that IFNA Response and IFNG Response were the top two gene sets selectively induced in Mtb-infected AM. Thus, a second experiment utilized MDMs treated with IFNA1, IFNA8, IFNE, or IFNL1 found that IFNA8 modulated Mtb-induced pro-inflammatory cytokines and, compared to other interferons,stimulated unique transcriptional profiles.
Project description:CD4 T cells are essential for immunity to tuberculosis because they produce cytokines including interferon-γ. Whether CD4 T cells act as “helper” cells to promote optimal CD8 T cell responses during Mycobacterium tuberculosis (Mtb) is unknown. We compared transcriptomes of purified lung CD8 T cells from Mtb infected WT and MHCII KO mice. Using two independent models, we validated RNA-seq results and showed that CD4 T cell help enhanced CD8 effector functions and prevented CD8 T cell exhaustion. We demonstrated synergy between CD4 and CD8 T cells in promoting the survival of infected mice. Purified helped, but not helpless, CD8 T cells efficiently restricted intracellular bacterial growth in vitro. Thus, CD4 T cell help plays an essential role in generating protective CD8 T cell responses against M. tuberculosis infection in vitro and in vivo. We infer vaccines that elicit both CD4 and CD8 T cells are more likely to be successful than vaccines that elicit only CD4 or CD8 T cells.
Project description:HIV establishes long-term latent infection in memory CD4+ T cells, but also establishes sustained long-term productive infection in macrophages, especially in the CNS. To better understand how HIV sustains infection in macrophages, we performed RNAseq analysis after infection of human-monocyte derived macrophages (MDMs) with the brain-derived HIV-1 strain YU2 and compared this with acute infection of CD4+ T cells. HIV infection in MDM and CD4+ T-cells altered many gene transcripts, but with few overlaps between these different cell types. We found interferon pathways upregulated in both MDM and CD4+ T-cells, but with different gene signatures. The interferon-stimulated gene RSAD2/Viperin was among the most upregulated genes following HIV infection in MDMs, but not in CD4+ T-cells. RSAD2/Viperin was induced early after infection with various HIV strains, was sustained over time, and remained elevated in established MDM infection even if new rounds of infection were blocked by antiretroviral treatment. Immunofluorescence microscopy revealed that RSAD2/Viperin was induced strongly in HIV infected cells, as well as in some uninfected neighboring cells, and was frequently localized at junctions between cells. Knockdown of RSAD2/Viperin following establishment of infection in MDMs reduced production of HIV transcripts and viral p24 antigen. This correlated with reduction in the number of multinucleated giant cells, and changes in the histone modifications at the HIV LTR, including loss of histone H3K7ac and H3K9me3, epigenetic marks that we have found associated with HIV in MDMs. RNA-seq transcriptomic analysis of RSAD2/Viperin knockdown during HIV infection of MDMs revealed activation of interferon alpha and gamma pathways and inactivation of Rho GTPase pathways. Taken together, these results suggest that RSAD2/Viperin supports HIV infection in macrophages through multiple mechanisms, potentially including the attenuation of the interferon response.
Project description:Innate memory phenotype (IMP) CD4+ T cells are non-conventional αβ T cells exhibiting features of innate immune cells, characterized as CD44high and CD62Llow in periphery. It is recently reported by our group that bone marrow chimeric mice lacking thymic MHCI expression develop predominantly IMP CD8+ T cells, while those lacking hematopoietic MHCI develop predominantly naïve CD8+ T cells. Here we perform hirarchical clustering analysis and found that CD4+ T cells share similar property: chimeras lacking thymic MHCII gave rise to predominantly CD4+ T cells that resemble IMP CD4+ T cells observed in WT mice, and vice versa, chimeras lacking hematopoietic MHCII had a majority of naïve-like CD4+ T cells resembling naïveCD4+ T cells seen in WT mice. We used microarrays to compare the global programme of gene expression to determine whether the hematopoietic MHCII selected CD4+ T cells are IMP, and whether the thymic MHCII selected CD4+ T cells are naïve CD4+ T cells as observed in WT mice. Through hierarchical clustering and analysis of global gene differential expression, we determined that hematopoietic MHCII dependent IMP CD4+ T cells generated from WT bone marrow transplanted into irradiated MHCII-/- recipients, resemble IMP CD4+ T cells in WT mice, while naïve CD4+ T cells generated from MHCII-/- bone marrow transplanted into irradiated WT recipients, resemble naïve CD4+ T cells in WT mice. Cell Sorting was performed using a Cytopeia Influx Cell Sorter. Chimeric IMP (CD45.1+TCRβ+CD4+CD44highCD62Llow) CD4+ T cells were sorted from splenocytes of CD45.1+WTâCD45.2+MHCII-/- chimeras (WM IMP CD4), and chimeric naïve (CD45.2+TCRβ+CD4+CD44lowCD62Lhigh) CD4+ T cells were sorted from splenocytes of CD45.2+MHCII-/- â CD45.1+WT chimeras (MW naïve CD4) respectively, 8 weeks post transplantation. WT IMP (TCRβ+CD4+CD44highCD62Llow) and naïve (TCRβ+CD4+CD44lowCD62Lhigh) CD4+ T cells were sorted from splenocytes of 8-week old WT mice.
Project description:Cytokine-mediated activation of host immunity is central to the control of pathogens. Interferon-gamma (IFNg) is a key cytokine in protective immunity that induces major histocompatibility complex class II molecules (MHCII) to amplify CD4+ T cell activation and effector function. Despite its central role, the dynamic regulation of IFNg-induced MHCII is not well understood. Using a genome-wide CRISPR-Cas9 screen in murine macrophages we globally identified genes that control MHCII surface expression. Mechanistic studies uncovered two parallel pathways of IFNg-mediated MHCII control that require the multifunctional glycogen synthase kinase 3 beta (GSK3b) or the mediator complex subunit MED16. Both pathways control distinct aspects of the IFNg response and are necessary for IFNg-mediated induction of the MHCII transactivator CIITA, MHCII expression, and CD4+ T cell activation. Our results define previously unappreciated regulation of MHCII expression that is required to control CD4+ T cell responses.
Project description:A growing body of evidence supports the importance of T cell responses to protect against severe influenza, promote viral clearance and ensure long-term immunity. Plant-derived virus-like particle (VLP) vaccines bearing influenza hemagglutinin (HA) have been shown to elicit strong humoral and CD4+ T cell responses in both pre-clinical and clinical studies. To better understand the immunogenicity of theses vaccines, we tracked the intracellular fate of a model HA (A/California/07/2009 H1N1) in human monocyte-derived macrophages (MDMs) following delivery either as VLPs (H1-VLP) or in soluble form. High-resolution tandem mass spectrometry identified 131 HA-derived peptides associated with MHC I in the H1-VLP-treated MDMs. Together with immunostaining and microscopy results, these data suggest that HA delivery to antigen-presenting cells on plant-derived VLPs facilitates antigen uptake, endosomal processing and cross-presentation. These observations may help explain the broad and cross-reactive immune responses generated by these vaccines.
Project description:To summarize our results, we found microglia and MDMs are functionally heterogeneous population contributing differently to the disease phenotype. Our data, suggest that during post-ischemic inflammation microglia exhibit pro-inflammatory phenotype, while infiltrating MDMs display anti-inflammatory and neuro-protective phenotype. Apart from up-regulation of some of the classical M2 marker in MDMs, our gene expression profiling using RNA-sequencing revealed a unique signature of MDMs with the up-regulation of genes associated with wound healing, MHCII antigen-presentation and tissue repair. Our results strongly suggest that MDMs infiltrating the CNS parenchyma during the sub-acute of post-ischemic inflammation might contribute to the endogenous mechanism of neuroprotection.
Project description:Innate memory phenotype (IMP) CD4+ T cells are non-conventional αβ T cells exhibiting features of innate immune cells, characterized as CD44high and CD62Llow in periphery. It is recently reported by our group that bone marrow chimeric mice lacking thymic MHCI expression develop predominantly IMP CD8+ T cells, while those lacking hematopoietic MHCI develop predominantly naïve CD8+ T cells. Here we perform hirarchical clustering analysis and found that CD4+ T cells share similar property: chimeras lacking thymic MHCII gave rise to predominantly CD4+ T cells that resemble IMP CD4+ T cells observed in WT mice, and vice versa, chimeras lacking hematopoietic MHCII had a majority of naïve-like CD4+ T cells resembling naïveCD4+ T cells seen in WT mice. We used microarrays to compare the global programme of gene expression to determine whether the hematopoietic MHCII selected CD4+ T cells are IMP, and whether the thymic MHCII selected CD4+ T cells are naïve CD4+ T cells as observed in WT mice. Through hierarchical clustering and analysis of global gene differential expression, we determined that hematopoietic MHCII dependent IMP CD4+ T cells generated from WT bone marrow transplanted into irradiated MHCII-/- recipients, resemble IMP CD4+ T cells in WT mice, while naïve CD4+ T cells generated from MHCII-/- bone marrow transplanted into irradiated WT recipients, resemble naïve CD4+ T cells in WT mice.