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Muñoz-Sánchez S, Varela M, van der Vaart M, Meijer AH. Using Zebrafish to Dissect the Interaction of Mycobacteria with the Autophagic Machinery in Macrophages. BIOLOGY 2023; 12:817. [PMID: 37372102 DOI: 10.3390/biology12060817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 05/24/2023] [Accepted: 05/31/2023] [Indexed: 06/29/2023]
Abstract
Existing drug treatment against tuberculosis is no match against the increasing number of multi-drug resistant strains of its causative agent, Mycobacterium tuberculosis (Mtb). A better understanding of how mycobacteria subvert the host immune defenses is crucial for developing novel therapeutic strategies. A potential approach is enhancing the activity of the autophagy machinery, which can direct bacteria to autophagolysosomal degradation. However, the interplay specifics between mycobacteria and the autophagy machinery must be better understood. Here, we analyzed live imaging data from the zebrafish model of tuberculosis to characterize mycobacteria-autophagy interactions during the early stages of infection in vivo. For high-resolution imaging, we microinjected fluorescent Mycobacterium marinum (Mm) into the tail fin tissue of zebrafish larvae carrying the GFP-LC3 autophagy reporter. We detected phagocytosed Mm clusters and LC3-positive Mm-containing vesicles within the first hour of infection. LC3 associations with these vesicles were transient and heterogeneous, ranging from simple vesicles to complex compound structures, dynamically changing shape by fusions between Mm-containing and empty vesicles. LC3-Mm-vesicles could adopt elongated shapes during cell migration or alternate between spacious and compact morphologies. LC3-Mm-vesicles were also observed in cells reverse migrating from the infection site, indicating that the autophagy machinery fails to control infection before tissue dissemination.
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Affiliation(s)
- Salomé Muñoz-Sánchez
- Institute of Biology Leiden, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands
| | - Mónica Varela
- Institute of Biology Leiden, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands
| | - Michiel van der Vaart
- Institute of Biology Leiden, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands
| | - Annemarie H Meijer
- Institute of Biology Leiden, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands
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Lenz SM, Ray NA, Lema T, Collins JH, Thapa R, Girma S, Balagon M, Bobosha K, Hagge DA, Williams DL, Scollard DM, Lahiri R, Adams LB. Utility of a Mycobacterium leprae molecular viability assay for clinical leprosy: An analysis of cases from the Philippines, Ethiopia, and Nepal. FRONTIERS IN TROPICAL DISEASES 2022. [DOI: 10.3389/fitd.2022.967351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Mycobacterium leprae is a slow-growing species of mycobacteria that cannot be cultured in axenic media. This presents a number of challenges for monitoring treatment efficacy and advancing new drugs and regimens for treating leprosy. We previously developed a molecular viability assay (MVA) which measures expression of hsp18 and esxA transcripts to determine viability of M. leprae directly from infected tissue. The objective of the current study was to determine the utility of the MVA for practical use on clinical specimens. Leprosy cases from the Philippines (N = 199), Ethiopia (N = 40), and Nepal (N = 200) were diagnosed by clinical examination, slit-skin smears (SSS) from index sites, and/or histopathology. Biopsy specimens for MVA were collected from an active lesion and stored in 70% ethanol. DNA and RNA were extracted from the tissue, and M. leprae were enumerated on the DNA fraction via RLEP qPCR. Based on this count, DNased RNA was normalized to the equivalent of 3x103M. leprae per reverse transcription reaction, and hsp18 and esxA transcripts were amplified by PCR on the resulting cDNA. There was a strong correlation between RLEP enumeration on the specific biopsy specimen for MVA and the average SSS bacterial index (BI) in all three cohorts (p < 0.001). The MVA could be performed on most biopsies with an average SSS BI ≥ 2 and showed a decrease in M. leprae viability with increasing duration of leprosy multidrug therapy (R2 = 0.81, p < 0.001). The MVA also detected viable M. leprae in relapse patients where it showed significant correlation with the mouse footpad assay (p = 0.018). The MVA is a M. leprae-specific, sensitive, and relatively quick test. Clinically, the MVA would likely be most useful to monitor treatment, confirm suspected relapse cases, and determine efficacy of new leprosy drugs in clinical trials.
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Osman MM, Shanahan JK, Chu F, Takaki KK, Pinckert ML, Pagán AJ, Brosch R, Conrad WH, Ramakrishnan L. The C terminus of the mycobacterium ESX-1 secretion system substrate ESAT-6 is required for phagosomal membrane damage and virulence. Proc Natl Acad Sci U S A 2022; 119:e2122161119. [PMID: 35271388 PMCID: PMC8931374 DOI: 10.1073/pnas.2122161119] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 01/15/2022] [Indexed: 12/21/2022] Open
Abstract
SignificanceTuberculosis (TB), an ancient disease of humanity, continues to be a major cause of worldwide death. The causative agent of TB, Mycobacterium tuberculosis, and its close pathogenic relative Mycobacterium marinum, initially infect, evade, and exploit macrophages, a major host defense against invading pathogens. Within macrophages, mycobacteria reside within host membrane-bound compartments called phagosomes. Mycobacterium-induced damage of the phagosomal membranes is integral to pathogenesis, and this activity has been attributed to the specialized mycobacterial secretion system ESX-1, and particularly to ESAT-6, its major secreted protein. Here, we show that the integrity of the unstructured ESAT-6 C terminus is required for macrophage phagosomal damage, granuloma formation, and virulence.
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Affiliation(s)
- Morwan M. Osman
- Molecular Immunity Unit, Cambridge Institute of Therapeutic Immunology and Infectious Diseases, Department of Medicine, University of Cambridge, CB2 OQH Cambridge, United Kingdom
- Cell Biology Division, Medical Research Council Laboratory of Molecular Biology, CB2 0QH Cambridge, United Kingdom
| | - Jonathan K. Shanahan
- Molecular Immunity Unit, Cambridge Institute of Therapeutic Immunology and Infectious Diseases, Department of Medicine, University of Cambridge, CB2 OQH Cambridge, United Kingdom
- Cell Biology Division, Medical Research Council Laboratory of Molecular Biology, CB2 0QH Cambridge, United Kingdom
| | - Frances Chu
- Department of Microbiology, University of Washington, Seattle, WA 98105
| | - Kevin K. Takaki
- Molecular Immunity Unit, Cambridge Institute of Therapeutic Immunology and Infectious Diseases, Department of Medicine, University of Cambridge, CB2 OQH Cambridge, United Kingdom
- Cell Biology Division, Medical Research Council Laboratory of Molecular Biology, CB2 0QH Cambridge, United Kingdom
| | - Malte L. Pinckert
- Molecular Immunity Unit, Cambridge Institute of Therapeutic Immunology and Infectious Diseases, Department of Medicine, University of Cambridge, CB2 OQH Cambridge, United Kingdom
- Cell Biology Division, Medical Research Council Laboratory of Molecular Biology, CB2 0QH Cambridge, United Kingdom
| | - Antonio J. Pagán
- Molecular Immunity Unit, Cambridge Institute of Therapeutic Immunology and Infectious Diseases, Department of Medicine, University of Cambridge, CB2 OQH Cambridge, United Kingdom
- Cell Biology Division, Medical Research Council Laboratory of Molecular Biology, CB2 0QH Cambridge, United Kingdom
| | - Roland Brosch
- Institut Pasteur, Université de Paris, CNRS UMR 3525, Unit for Integrated Mycobacterial Pathogenomics, 75724 Paris Cedex 15, France
| | - William H. Conrad
- Molecular Immunity Unit, Cambridge Institute of Therapeutic Immunology and Infectious Diseases, Department of Medicine, University of Cambridge, CB2 OQH Cambridge, United Kingdom
- Cell Biology Division, Medical Research Council Laboratory of Molecular Biology, CB2 0QH Cambridge, United Kingdom
| | - Lalita Ramakrishnan
- Molecular Immunity Unit, Cambridge Institute of Therapeutic Immunology and Infectious Diseases, Department of Medicine, University of Cambridge, CB2 OQH Cambridge, United Kingdom
- Cell Biology Division, Medical Research Council Laboratory of Molecular Biology, CB2 0QH Cambridge, United Kingdom
- Department of Microbiology, University of Washington, Seattle, WA 98105
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