Specificity of the innate immune responses to different classes of non-tuberculous mycobacteria
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ABSTRACT: Mycobacterium avium is the most common nontuberculous mycobacterium (NTM) species causing infectious disease. Here, we characterized a M. avium infection model in zebrafish larvae, and compared it to M. marinum infection, a model of tuberculosis. Using RNAseq analysis, we found a distinct transcriptome response in cytokine-cytokine receptor interaction for M. avium and M. marinum infection. In addition, we found substantial differences in gene expression in metabolic pathways, phagosome formation, matrix remodeling, and apoptosis in response to these mycobacterial infections.
Project description:An opportunistic intracellular pathogen Mycobacterium avium subsp. hominissuis, a member of the nontuberculous mycobacteria (NTM) cluster, causes respiratory disease in immunosuppressed hosts. In particular, infected companion dogs are a potential role to transmit the agent to children or immunosuppressed people. The purpose of this study is to investigate a host-M. avium hominissuis interactome in canine PBMCs during the infection.
Project description:To understand nontuberculous mycobacterial (NTM) pathogenesis, we evaluated immune responses to Mycobacterium avium (Mav) in asymptomatic individuals with a previous history of M. avium complex lung disease (MACDZ). We analyzed global gene expression in paired Mav-infected and uninfected peripheral blood monocytes from 17 MACDZ and 17 healthy controls.
Project description:The incidence of pulmonary nontuberculous mycobacterial (PNTM) disease is increasing, but host susceptibility factors are not fully understood. We infected air-liquid interface (ALI) primary respiratory epithelial cell cultures with Mycobacterium avium complex (MAC) or Mycobacterium abscessus (MAB) and performed transcriptome sequencing (RNA-Seq) to identify relevant gene expression differences. We used cells from 4 different donors in order to try to obtain generalizable data. The differentiated respiratory epithelial cells in ALI were infected with MAC or MAB at MOI of 100:1 or 1000:1, and RNA-seq was performed at 1 and 3 days after infection. We found downregulation of ciliary genes, including several identified with polymorphisms in previous PNTM cohorts. The cytokine IL-32, the superpathway of cholesterol biosynthesis and downstream targets within the IL-17 signaling pathway were all elevated. The integrin signaling pathway was more upregulated by MAB than MAC infection. Working with primary respiratory epithelial cells infected with nontuberculous mycobacteria at ALI, we identified ciliary function, cholesterol biosynthesis, chemokine production and the IL-17 pathway as major targets of host responses to infection. Some of these pathways may be amenable to therapeutic manipulation.
Project description:Bacille Calmette Guerin (BCG) is the only licensed vaccine against Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB) disease. However, BCG has limited efficacy, necessitating the development of better vaccines. Non-tuberculous mycobacteria (NTM), a distinct lineage from Mtb, are opportunistic pathogens present in the environment. TB endemic countries experience higher exposure to NTM, but previous studies have not elucidated the relationship between NTM exposure and BCG efficacy. Therefore, we developed a mouse model (BCG+NTM) that mimics human BCG vaccination at an early stage and continuous NTM exposure via the oral route, including during TB infection. Our results show that BCG+NTM mice had improved protection against pulmonary TB correlating with increased pulmonary influx of B-cells, higher titers of anti-Mtb IgA and IgG antibodies in serum and airways, compared to mice vaccinated with BCG alone. Notably, the lungs of BCG+NTM mice developed B-cell aggregates expressing markers of germinal center formation as determined by spatial transcriptomics. We conclude a direct correlation between NTM exposure and protection from TB, with B-cells playing a crucial role.
Project description:An opportunistic intracellular pathogen Mycobacterium intracellulare, a member of the nontuberculous mycobacteria (NTM) cluster, causes respiratory disease in immunosuppressed hosts, including companion dogs. The purpose of this study is to investigate a host-M.intracellulare interactome in canine monocyte-derived macrophages during the infection.
Project description:Aging has a significant impact on the immune system, leading to a gradual decline in immune function and changes in the body's ability to respond to bacterial infections. Non-tuberculous mycobacteria (NTM), also known as atypical mycobacteria or environmental mycobacteria, are commonly found in soil, water, and various environmental sources. While many NTM species are considered opportunistic pathogens, some can cause significant infections, particularly in individuals with compromised immune systems, such as the elderly. When mycobacteria enter the body, macrophages are among the first immune cells to encounter them, and attempt to engulf mycobacteria through a process called phagocytosis. Some NTM species, including Mycobacterium avium (M.avium) can survive and replicate within macrophages. However, little is known about the interaction between NTM and macrophages in the elderly. In this study, we investigated the mouse bone marrow-derived macrophage (BMMs) response to M. avium serotype 4, one of the main NTM species in patients with pulmonary NTM diseases. Our results demonstrated that old mouse BMMs have an increased level of intracellular iron and are more susceptible to M. avium serotype 4 infection compared to young mouse BMMs. The whole-cell proteomic analysis indicated a dysregulated expression of iron homeostasis-associated proteins in old mouse BMMs regardless of mycobacterial infection. Deferoxamine, an iron chelator, significantly rescued mycobacterial killing and phagolysosome maturation in old mouse BMMs. Therefore, our data indicate that an intracellular iron overload improves NTM survival within macrophages, and suggest a potential application of iron chelating drugs as a host-directed therapy for pulmonary NTM infection in the elderly
Project description:Once entering the cell, M. avium subsp.paratuberculosis is known to survive harsh microenvironments, especially those inside activated macrophages. To improve our understanding of M. avium subsp.paratuberculosis pathogenesis, we examined the phagosome maturation associated with transcriptional responses of M. avium subsp.paratuberculosis during macrophage infection. Monitoring cellular markers, only live M. avium subsp.paratuberculosis bacilli were able to prevent phagosome maturation and reduce its acidification. On the transcriptional level, over 300 of M. avium subsp.paratuberculosis genes were significantly, differentially regulated in both naM-CM-/ve and IFN-M-NM-3-activated macrophages. These genes include the sigma factor H (sigH) that was shown to be important during persistent infection in M. tuberculosis. Bacterial total RNA was purified from Mycobacterium avium subsp. paratuberculosis that was infected into J774A.1 cells grown with or without interferon-gamma activation at 2 or 24 h post-infection. RNA from bacteria incubated with PRMI-1640 medium for 2 h, which was the infection conditon, is used as control condition. Each condition has two biological replicates. Each hybridization represents expression levels of all 4,350 annotated genes with 20 60-mer oligonucleotides and with three technical replicates.
Project description:Detection of species-specific proteotypic peptides for accurate and easy characterization of infectious non-tuberculous mycobacteria such as Mycobacterium avium subsp. paratuberculosis, Mycobacterium marinum and Mycobacterium vaccae is essential. Therefore, we carried out reanalysis of publicly available M. avium subsp. paratuberculosis, M. marinum and M. vaccae proteomic dataset PXD027444, PXD003766 and PASS00954 by proteome database search and followed by spectral library generation. The raw DDA data were searched against their respective reference proteome databases using Proteome Discoverer and FragPipe. The resulting peptide spectrum matches were converted into a spectral library using BiblioSpec.
Project description:Scavenger receptors on the cell surface of macrophages play an important role in host defence through their ability to bind microbial ligands and induce phagocytosis. Concurrently, signal transduction pathways are initiated that aid in defence mechanisms against the invading microbe. Here we report on the function of scavenger receptor Marco (macrophage receptor with collagenous structure) during infection of zebrafish embryos with Mycobacterium marinum, a close relative of Mycobacterium tuberculosis. Morpholino knockdown demonstrates that Marco is required for the rapid phagocytosis of M. marinum following intravenous infection. Furthermore, gene expression analysis shows that Marco controls the initial transient pro-inflammatory response to M. marinum and remains a determining factor for the immune response signature at later stages of infection. Increased bacterial burden following marco knockdown indicates that this scavenger receptor is important for control of M. marinum growth, likely due to delayed phagocytosis and reduced pro-inflammatory signalling observed under conditions of Marco deficiency
Project description:Once entering the cell, M. avium subsp.paratuberculosis is known to survive harsh microenvironments, especially those inside activated macrophages. To improve our understanding of M. avium subsp.paratuberculosis pathogenesis, we examined the phagosome maturation associated with transcriptional responses of M. avium subsp.paratuberculosis during macrophage infection. Monitoring cellular markers, only live M. avium subsp.paratuberculosis bacilli were able to prevent phagosome maturation and reduce its acidification. On the transcriptional level, over 300 of M. avium subsp.paratuberculosis genes were significantly, differentially regulated in both naïve and IFN-γ-activated macrophages. These genes include the sigma factor H (sigH) that was shown to be important during persistent infection in M. tuberculosis.