Project description:The innate immune system provides the first response to pathogen infection and orchestrates the activation of the adaptive immune system. Though a large component of the innate immune response is common to all infections, pathogen-specific innate immune responses have been documented as well. The innate immune response is thought to be especially critical for fighting infection with Mycobacterium tuberculosis (MTB), the causative agent of tuberculosis (TB). While TB can be a deadly disease, only 5-10% of individuals infected with MTB develop active disease, and this inter-individual variation is, at least partly, heritable. Studies of inter-individual variation in the innate immune response to MTB infection may therefore shed light on the genetic basis for variation in susceptibility to TB. Yet, to date, we still do not know which properties of the innate immune response are specific to MTB infection and which represent a general response to pathogen infection. To begin addressing this gap, we infected macrophages with eight different bacterial pathogens, including different MTB strains and related mycobacteria, and studied the transcriptional response to infection. We found that although the gene expression changes were largely consistent across the bacterial infection treatments, we were able to identify a novel subset of genes whose regulation was affected specifically by infection with mycobacteria. Genetic variants that are associated with regulatory differences in these genes should be considered candidate loci for explaining inter-individual susceptibility TB. RNA-seq of monocyte-derived macrophages isolated from 6 healthy European males at 4, 18, and 48 hours post-infection with the following 8 bacteria: Mycobacterium tuberculosis (MTB) H37Rv, Mycobacterium tuberculosis GC1237, MTB GC1237, bacillus Calmette-Guérin (BCG), Mycobacterium smegmatis, Yersinia pseudotuberculosis, Salmonella typhimurium, and Staphylococcus epidermidis. table-s1.txt is a tab-delimited text file that contains the batch-corrected log2 counts per million for each of the 156 samples, as well as the Ensembl gene ID and gene name. BCG = bacillus Calmette-Guérin GC = Mycobacterium tuberculosis GC1237 Rv = Mycobacterium tuberculosis (MTB) H37Rv Rv+ = heat-inactivated MTB H37Rv Salm = Salmonella typhimurium Smeg = Mycobacterium smegmatis Staph = Staphylococcus epidermidis Yers = Yersinia pseudotuberculosis

Project description:Background: Tuberculosis (TB) remains a major public health problem, especially in developing countries, with 1.5 million deaths annually worldwide. Antibiotics are commonly used in the treatment of bacterial infections. As with most drugs, antibiotic treatment can also alter host metabolism, leading to adverse side-effects. Antibiotics can also interfere with the immune system, indirectly through the disturbance of the body’s microbiota or directly by modulating the functions of immune cells. It is therefore important to understand how antibiotic treatment modulates immune cell functions. Here we aim to evaluate the impact of first-line anti-TB drugs on the response of human macrophages infected with Mycobacterium tuberculosis (MTB). Results: Human macrophages were stimulated with heat-killed Mycobacterium tuberculosis (hk-MTB) and treated with isoniazid (INH), rifampicin (RIF), ethambutol, pyrazinamide (PZA) or amikacin (AMK). After 24h of treatment, RNA was collected and we characterized the genome-wide gene expression profiles of drug-treated cells by RNAseq. 556, 752 and 7 genes were differentially expressed in hk-MTB-stimulated macrophages upon RIF, PZA and EMB treatment respectively, whereas in uninfected macrophages, 448 and 11 genes were differentially expressed upon RIF and PZA treatment respectively. No genes were differentially expressed upon INH and AMK treatment. We classified all modulated genes by performing gene-set enrichment analysis. The gene set regulated by PZA in infected macrophages was significantly enriched for genes involved in Integral to lumenal side of endoplasmic reticulum membrane, Cytokine-mediated signaling pathway or Interferon-gamma-mediated signaling pathway. In hk-MTB-stimulated macrophages treated by RIF, we found an enrichment in Endoplasmic reticulum unfolded protein response, NADP binding or Lipid metabolic process. Conclusions: Our results highlight the importance to understand how antibiotic treatment modulates macrophage (Mφ) functions, and more generally, how it impacts the host immune response.

Project description:Tuberculosis, caused by M.tuberculosis (Mtb), remains an enduring global health challenge, especially given the limited efficacy of current therapeutic interventions. Much of existing research has focused on immune failure as a driver of tuberculosis. However, the crucial role of host macrophage biology in controlling the disease remains underexplored. While we have gained deeper insights into how alveolar macrophages (AMs) interact with Mtb, the precise AM subsets that mediate protection and potentially prevent tuberculosis progression have yet to be identified. In this study, by integrating the use of weighted gene correlation network analysis (WGCNA) modules with our multi-modal scRNA-seq protocol, we were able to evaluate the functional roles of diverse macrophage subpopulations across different infection timepoints, allowing us to delineate the dynamic landscape of controller and permissive AM populations throughout the infection timeline. Our analyses during specific post-Mtb challenge intervals revealed macrophage populations transitioning between distinct anti- and pro-inflammatory states. Notably, CD38- AMs showed a muted response to early Mtb infection. As infection progressed, we observed a phenotypic shift in AMs, with CD38+ monocyte-derived AMs (moAMs) and a subset of tissue-resident AMs (TR-AMs) emerging as significant controllers of bacterial growth. Interestingly, scATAC-seq analysis of naïve lungs demonstrated that CD38+ TR-AMs possessed a distinct chromatin signature prior to infection, indicative of epigenetic priming, and predisposed them to a pro-inflammatory response. BCG intranasal immunization increased the numbers of CD38+ macrophages, substantially enhancing their capability to restrict Mtb growth. Collectively, our findings emphasize the pivotal, dynamic roles of different macrophage subsets in TB infection and reveal rational pathways for the development of improved vaccines and immunotherapeutic strategies, with implications for the broader field of infectious diseases.

Project description:Although host genetics influences susceptibility to tuberculosis, few genes determining disease outcome have been identified. We hypothesized that macrophages from individuals with different clinical manifestations of tuberculosis infection would have distinct gene expression profiles, and that polymorphisms in these genes may also be associated with susceptibility to TB. We measured gene expression levels of >38,500 genes from ex vivo Mtb- stimulated macrophages in 12 subjects with 3 clinical phenotypes: latent, pulmonary and meningeal tuberculosis (n=4 per group). After identifying differentially expressed genes, we confirmed these results in 34 additional subjects by real-time PCR. We also used a case-control study design to examine whether polymorphisms in differentially regulated genes were associated with susceptibility to these different clinical forms of TB. We compared gene expression profiles in Mtb-stimulated and unstimulated macrophages and identified 1608 and 199 genes that were differentially expressed by >2 and >5-fold, respectively. Using cluster analysis, we identified gene expression patterns that distinguished the different clinical forms of tuberculosis. In an independent sample set of 34 individuals and a subset of highly regulated genes, 90% of the microarray results were confirmed by RT-PCR, including expression levels of CCL1, which distinguished the 3 clinical groups. Furthermore, 6 single nucleotide polymorphisms (SNPs) in CCL1 were found to be associated with TB in a case-control genetic association study with 273 TB cases and 188 controls. To our knowledge, this is the first identification of CCL1 as a gene involved in host susceptibility to TB and the first study to combine microarray and DNA polymorphism studies to identify genes associated with TB susceptibility. These results suggest that genome-wide studies can provide an unbiased method to identify critical macrophage response genes that are associated with different clinical outcomes and that variation in innate immune response genes regulate susceptibility to tuberculosis. Experiment Overall Design: Latent TB (LTB) subjects were healthy nursing staff members who had worked at a tuberculosis hospital, for more than 20 years and were positive in ESAT-6 and CFP-10- specific IFN-ï?§ ELISPOT assays. All subjects with pulmonary (PTB) and meningeal (TBM) disease had been treated and were free of symptoms at the time of venipuncture. Gene expression of monocyte derived macrophages (MDMs) from subjects with three clinical forms of TB including LTB, PTB and TBM (n = 4 in each group) was examined by microarray. MDMs were stimulated either with a whole cell lysate of M. tuberculosis H37Rv or PBS for 4 hours. RNA expression was analyzed using a Human Genome U133 Plus 2.0 Array (Affymetrix, USA) which contains probe sets for 47,000 transcripts including 38,500 well-characterized human genes.

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Inactivated M. tuberculosis and M.tuberculosis Infection remodels the macrophage response

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