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Shi C, Huang X, Wang D, Chu C, Shi Y, Yan B, Shan F, Zhang J, Zhang Z, Peng C, Tang BZ. Lipophilic AIEgens as the "Trojan Horse" with Discrepant Efficacy in Tracking and Treatment of Mycobacterial Infection. Adv Healthc Mater 2024; 13:e2301746. [PMID: 37747232 DOI: 10.1002/adhm.202301746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 08/07/2023] [Indexed: 09/26/2023]
Abstract
The highly contagious tuberculosis is a leading infectious killer, which urgently requires effective diagnosis and treatment methods. To address these issues, three lipophilic aggregation-induced emission (AIE) photosensitizers (TTMN, TTTMN, and MeOTTMN) are selected to evaluate their labeling and antimicrobial properties in vitro and in vivo. These three lipophilic AIEgens preserve low cytotoxicity and achieve real-time and non-invasive visualization of the process of mycobacteria infection in vitro and in vivo. More importantly, these AIEgens can be triggered by white light to produce reactive oxygen species (ROS), which is a highly efficient antibacterial reagent. Among these AIEgens, the TTMN photosensitizer has an outstanding antibacterial efficacy over the clinical first-line drug rifampicin at the same therapeutic concentration. Interestingly, this study also finds that TTMN can increase the expression of pro-inflammatory cytokines in the early stage of infection after light irradiation, indicating an additional pro-inflammatory role of TTMN. This work provides some feasibility basis for developing AIEgens-based agents for effectively destroying mycobacterium.
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Affiliation(s)
- Chunzi Shi
- Qingdao Institute, School of Life Medicine, Department of Radiology, Shanghai Public Health Clinical Center, Fudan University, Qingdao, 266500, China
- Department of Radiology, Ruijin Hospital, Shanghai Jiao Tong University, School of Medicine, Shanghai, 200025, China
| | - Xueni Huang
- Qingdao Institute, School of Life Medicine, Department of Radiology, Shanghai Public Health Clinical Center, Fudan University, Qingdao, 266500, China
| | - Dong Wang
- Center for AIE Research, Shenzhen Key Laboratory of Polymer Science and Technology, Guangdong Research Center for Interfacial Engineering of Functional Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Chengshengze Chu
- School of Science and Engineering, Shenzhen Institute of Aggregate Science and Technology, The Chinese University of Hong Kong, Shenzhen, 518172, China
| | - Yuxin Shi
- Qingdao Institute, School of Life Medicine, Department of Radiology, Shanghai Public Health Clinical Center, Fudan University, Qingdao, 266500, China
| | - Bo Yan
- Qingdao Institute, School of Life Medicine, Department of Radiology, Shanghai Public Health Clinical Center, Fudan University, Qingdao, 266500, China
| | - Fei Shan
- Qingdao Institute, School of Life Medicine, Department of Radiology, Shanghai Public Health Clinical Center, Fudan University, Qingdao, 266500, China
| | - Jiulong Zhang
- Qingdao Institute, School of Life Medicine, Department of Radiology, Shanghai Public Health Clinical Center, Fudan University, Qingdao, 266500, China
| | - Zhiyong Zhang
- Qingdao Institute, School of Life Medicine, Department of Radiology, Shanghai Public Health Clinical Center, Fudan University, Qingdao, 266500, China
| | - Chen Peng
- Qingdao Institute, School of Life Medicine, Department of Radiology, Shanghai Public Health Clinical Center, Fudan University, Qingdao, 266500, China
| | - Ben Zhong Tang
- School of Science and Engineering, Shenzhen Institute of Aggregate Science and Technology, The Chinese University of Hong Kong, Shenzhen, 518172, China
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Dai T, Xie J, Zhu Q, Kamariza M, Jiang K, Bertozzi CR, Rao J. A Fluorogenic Trehalose Probe for Tracking Phagocytosed Mycobacterium tuberculosis. J Am Chem Soc 2020; 142:15259-15264. [DOI: 10.1021/jacs.0c07700] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Tingting Dai
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Jinghang Xie
- Department of Radiology, Molecular Imaging Program at Stanford, Stanford University School of Medicine, Stanford, California 94305, United States
| | - Qihua Zhu
- Department of Radiology, Molecular Imaging Program at Stanford, Stanford University School of Medicine, Stanford, California 94305, United States
- State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, 211198, China
- Jiangsu Key Laboratory of Drug Design and Optimization, Department of Medicinal Chemistry, China Pharmaceutical University, Nanjing 211198, China
| | - Mireille Kamariza
- Department of Biology, Stanford University, Stanford, California 94305, United States
| | - Ke Jiang
- Department of Radiology, Molecular Imaging Program at Stanford, Stanford University School of Medicine, Stanford, California 94305, United States
| | - Carolyn R. Bertozzi
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
- Howard Hughes Medical Institute, Stanford University, Stanford, California 94305, United States
| | - Jianghong Rao
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
- Department of Radiology, Molecular Imaging Program at Stanford, Stanford University School of Medicine, Stanford, California 94305, United States
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Nascimento LV, Santos CC, Leite LC, Nascimento IP. Characterisation of alternative expression vectors for recombinant Bacillus Calmette-Guérin as live bacterial delivery systems. Mem Inst Oswaldo Cruz 2020; 115:e190347. [PMID: 32428188 PMCID: PMC7227789 DOI: 10.1590/0074-02760190347] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Accepted: 04/13/2020] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Bacillus Calmette-Guérin (BCG) is considered a promising live bacterial delivery system. However, several proposals for rBCG vaccines have not progressed, mainly due to the limitations of the available expression systems. OBJECTIVES To obtain a set of mycobacterial vectors using a range of promoters with different strengths based on a standard backbone, previously shown to be stable. METHODS Mycobacterial expression vectors based on the pLA71 vector as backbone, were obtained inserting different promoters (PAN, PαAg, PHsp60, PBlaF* and PL5) and the green fluorescence protein (GFP) as reporter gene, to evaluate features such as their relative strengths, and the in vitro (inside macrophages) and in vivo stability. FINDINGS The relative fluorescence observed with the different vectors showed increasing strength of the promoters: PAN was the weakest in both Mycobacterium smegmatis and BCG and PBlaF* was higher than PHsp60 in BCG. The relative fluorescence observed in a macrophage cell line showed that PBlaF* and PHsp60 were comparable. It was not possible to obtain strains transformed with the extrachromosomal expression vector containing the PL5 in either species. MAIN CONCLUSION We have obtained a set of potentially stable mycobacterial vectors with a arrange of expression levels, to be used in the development of rBCG vaccines.
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Affiliation(s)
- Larissa V Nascimento
- Laboratório Especial de Desenvolvimento de Vacinas, Instituto Butantan, São Paulo, SP, Brazil
| | - Carina C Santos
- Departamento de Análises Clínicas e Toxicológicas, Faculdade de Farmácia, Universidade Federal da Bahia, Salvador, BA, Brazil
| | - Luciana Cc Leite
- Laboratório Especial de Desenvolvimento de Vacinas, Instituto Butantan, São Paulo, SP, Brazil
| | - Ivan P Nascimento
- Laboratório Especial de Desenvolvimento de Vacinas, Instituto Butantan, São Paulo, SP, Brazil
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Mycobacterium avium subspecies paratuberculosis is able to manipulate host lipid metabolism and accumulate cholesterol within macrophages. Microb Pathog 2019; 130:44-53. [PMID: 30831227 DOI: 10.1016/j.micpath.2019.02.031] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 02/12/2019] [Accepted: 02/26/2019] [Indexed: 12/17/2022]
Abstract
Johne's disease is a chronic wasting disease of ruminants caused by Mycobacterium avium subspecies paratuberculosis (MAP). Closely related pathogenic mycobacteria such as M. tuberculosis are capable of altering host lipid metabolism, highlighting the need to explore the role of lipid metabolism contributing to intracellular survival. This study aimed to identify whether MAP is able to manipulate host lipid metabolic pathways and accumulate host cholesterol during early infection. Macrophages were exposed to four different MAP strains and non-pathogenic M. phlei for up to 72 h, with changes to lipid metabolism examined using fluorescent microscopy and gene expression. MAP-infected macrophages displayed strain-dependent differences to intracellular cholesterol levels during early infection, however showed similarly increased intracellular cholesterol at later timepoints. Gene expression revealed that MAP strains similarly activate the host immune response in a conserved manner compared to M. phlei. MAP significantly upregulated host genes associated with lipid efflux and endocytosis. Moreover, lipid biosynthesis genes were differentially regulated in a strain-dependent manner following MAP infection. Collectively, these results demonstrate that MAP manipulates host lipid metabolism during early infection, however the extent of these modulations are strain-dependent. These findings reflect a conserved pathway contributing to intracellular MAP survival.
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Diupotex M, Martínez-Salazar MB, Escalona-Montaño AR, Zamora-Chimal J, Salaiza-Suazo N, Ruiz-Remigio A, Roldán-Salgado A, Aguirre-García MM, Martínez-Calvillo S, Gaytán P, Becker I. The mKate fluorescent protein expressed by Leishmania mexicana modifies the parasite immunopathogenicity in BALB/c mice. Parasite Immunol 2019; 41:e12608. [PMID: 30500992 DOI: 10.1111/pim.12608] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 11/22/2018] [Accepted: 11/23/2018] [Indexed: 11/27/2022]
Abstract
Parasites have been engineered to express fluorescent reporter proteins, yet the impact of red fluorescent proteins on Leishmania infections remains largely unknown. We analysed the infection outcome of Leishmania mexicana parasites engineered for the constitutive expression of mKate protein and evaluated their immunogenicity in BALB/c mice. Infection of BALB/c mice with mKate transfected L. mexicana (LmexmKate ) parasites caused enlarged lesion sizes, leading to ulceration, and containing more parasites, as compared to LmexWT . The mKate protein showed immunogenic properties inducing antibody production against the mKate protein, as well as enhancing antibody production against the parasite. The augmented lesion sizes and ulcers, together with the more elevated antibody production, were related to an enhanced number of TNF-α and IL-1β producing cells in the infected tissues. We conclude that mKate red fluorescent protein is an immunogenic protein, capable of modifying disease evolution of L. mexicana.
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Affiliation(s)
- Mariana Diupotex
- Unidad de Investigación en Medicina Experimental, Facultad de Medicina, Universidad Nacional Autónoma de México, Hospital General de México, Ciudad de México, México
| | - María Berenice Martínez-Salazar
- Unidad de Investigación en Medicina Experimental, Facultad de Medicina, Universidad Nacional Autónoma de México, Hospital General de México, Ciudad de México, México
| | - Alma Reyna Escalona-Montaño
- Unidad de Investigación en Medicina Experimental, Facultad de Medicina, Universidad Nacional Autónoma de México, Hospital General de México, Ciudad de México, México
| | - Jaime Zamora-Chimal
- Unidad de Investigación en Medicina Experimental, Facultad de Medicina, Universidad Nacional Autónoma de México, Hospital General de México, Ciudad de México, México
| | - Norma Salaiza-Suazo
- Unidad de Investigación en Medicina Experimental, Facultad de Medicina, Universidad Nacional Autónoma de México, Hospital General de México, Ciudad de México, México
| | - Adriana Ruiz-Remigio
- Unidad de Investigación en Medicina Experimental, Facultad de Medicina, Universidad Nacional Autónoma de México, Hospital General de México, Ciudad de México, México
| | | | - María Magdalena Aguirre-García
- Unidad de Investigación en Medicina Experimental, Facultad de Medicina, Universidad Nacional Autónoma de México, Hospital General de México, Ciudad de México, México
| | - Santiago Martínez-Calvillo
- Unidad de Biomedicina, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Tlalnepantla, México
| | - Paul Gaytán
- Instituto de Biotecnología-Universidad Nacional Autónoma de México, Cuernavaca, México
| | - Ingeborg Becker
- Unidad de Investigación en Medicina Experimental, Facultad de Medicina, Universidad Nacional Autónoma de México, Hospital General de México, Ciudad de México, México
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Abshire CF, Prasai K, Soto I, Shi R, Concha M, Baddoo M, Flemington EK, Ennis DG, Scott RS, Harrison L. Exposure of Mycobacterium marinum to low-shear modeled microgravity: effect on growth, the transcriptome and survival under stress. NPJ Microgravity 2016; 2:16038. [PMID: 28725743 PMCID: PMC5515531 DOI: 10.1038/npjmgrav.2016.38] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Revised: 09/15/2016] [Accepted: 09/17/2016] [Indexed: 12/04/2022] Open
Abstract
Waterborne pathogenic mycobacteria can form biofilms, and certain species can cause hard-to-treat human lung infections. Astronaut health could therefore be compromised if the spacecraft environment or water becomes contaminated with pathogenic mycobacteria. This work uses Mycobacterium marinum to determine the physiological changes in a pathogenic mycobacteria grown under low-shear modeled microgravity (LSMMG). M. marinum were grown in high aspect ratio vessels (HARVs) using a rotary cell culture system subjected to LSMMG or the control orientation (normal gravity, NG) and the cultures used to determine bacterial growth, bacterium size, transcriptome changes, and resistance to stress. Two exposure times to LSMMG and NG were examined: bacteria were grown for ~40 h (short), or 4 days followed by re-dilution and growth for ~35 h (long). M. marinum exposed to LSMMG transitioned from exponential phase earlier than the NG culture. They were more sensitive to hydrogen peroxide but showed no change in resistance to gamma radiation or pH 3.5. RNA-Seq detected significantly altered transcript levels for 562 and 328 genes under LSMMG after short and long exposure times, respectively. Results suggest that LSMMG induced a reduction in translation, a downregulation of metabolism, an increase in lipid degradation, and increased chaperone and mycobactin expression. Sigma factor H (sigH) was the only sigma factor transcript induced by LSMMG after both short and long exposure times. In summary, transcriptome studies suggest that LSMMG may simulate a nutrient-deprived environment similar to that found within macrophage during infection. SigH is also implicated in the M. marinum LSMMG transcriptome response.
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Affiliation(s)
- Camille F Abshire
- Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center, Shreveport, LA, USA
| | - Kanchanjunga Prasai
- Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center, Shreveport, LA, USA
| | - Israel Soto
- Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center, Shreveport, LA, USA
| | - Runhua Shi
- Department of Medicine and Feist-Weiller Cancer Center, Louisiana State University Health Sciences Center, Shreveport, LA, USA
| | - Monica Concha
- Department of Pathology and Tulane Cancer Center, Tulane University Health Sciences Center, New Orleans, LA, USA
| | - Melody Baddoo
- Department of Pathology and Tulane Cancer Center, Tulane University Health Sciences Center, New Orleans, LA, USA
| | - Erik K Flemington
- Department of Pathology and Tulane Cancer Center, Tulane University Health Sciences Center, New Orleans, LA, USA
| | - Don G Ennis
- Department of Biology, University of Louisiana, Lafayette, LA, USA
| | - Rona S Scott
- Department of Microbiology and Immunology, Feist-Weiller Cancer Center, Louisiana State University Health Sciences Center, Shreveport, LA, USA
| | - Lynn Harrison
- Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center, Shreveport, LA, USA
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Jenner D, Ducker C, Clark G, Prior J, Rowland CA. Using multispectral imaging flow cytometry to assess an in vitro intracellular Burkholderia thailandensis infection model. Cytometry A 2016; 89:328-37. [PMID: 26841315 DOI: 10.1002/cyto.a.22809] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Revised: 10/02/2015] [Accepted: 12/03/2015] [Indexed: 01/10/2023]
Abstract
The use of in vitro models to understand the interaction of bacteria with host cells is well established. In vitro bacterial infection models are often used to quantify intracellular bacterial load by lysing cell populations and subsequently enumerating the bacteria. Modern established techniques employ the use of fluorescence technologies such as flow cytometry, fluorescent microscopy, and/or confocal microscopy. However, these techniques often lack either the quantification of large data sets (microscopy) or use of gross fluorescence signal which lacks the visual confirmation that can provide additional confidence in data sets. Multispectral imaging flow cytometry (MIFC) is a novel emerging field of technology. This technology captures a bright field and fluorescence image of cells in a flow using a charged coupled device camera. It allows the analysis of tens of thousands of single cell images, making it an extremely powerful technology. Here MIFC was used as an alternative method of analyzing intracellular bacterial infection using Burkholderia thailandensis E555 as a model organism. It has been demonstrated that the data produced using traditional enumeration is comparable to data analyzed using MIFC. It has also been shown that by using MIFC it is possible to generate other data on the dynamics of the infection model rather than viable counts alone. It has been demonstrated that it is possible to inhibit the uptake of bacteria into mammalian cells and identify differences between treated and untreated cell populations. The authors believe this to be the first use of MIFC to analyze a Burkholderia bacterial species during intracellular infection. © 2016 Crown copyright. Published by Wiley Periodicals Inc. on behalf of ISAC.
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Affiliation(s)
- Dominic Jenner
- Defence Science and Technology Laboratory, Biomedical Sciences Department, Porton down, Salisbury, SP4 0JQ, United Kingdom
| | - Catherine Ducker
- School of Biological Sciences, The University of Kent, Kent, Canterbury, CT2 7NZ, United Kingdom
| | - Graeme Clark
- Defence Science and Technology Laboratory, Biomedical Sciences Department, Porton down, Salisbury, SP4 0JQ, United Kingdom
| | - Jo Prior
- Defence Science and Technology Laboratory, Biomedical Sciences Department, Porton down, Salisbury, SP4 0JQ, United Kingdom
| | - Caroline A Rowland
- Defence Science and Technology Laboratory, Biomedical Sciences Department, Porton down, Salisbury, SP4 0JQ, United Kingdom
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Comparative Sigma Factor-mRNA Levels in Mycobacterium marinum under Stress Conditions and during Host Infection. PLoS One 2015; 10:e0139823. [PMID: 26445268 PMCID: PMC4596819 DOI: 10.1371/journal.pone.0139823] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Accepted: 08/14/2015] [Indexed: 11/28/2022] Open
Abstract
We have used RNASeq and qRT-PCR to study mRNA levels for all σ-factors in different Mycobacterium marinum strains under various growth and stress conditions. We also studied their levels in M. marinum from infected fish and mosquito larvae. The annotated σ-factors were expressed and transcripts varied in relation to growth and stress conditions. Some were highly abundant such as sigA, sigB, sigC, sigD, sigE and sigH while others were not. The σ-factor mRNA profiles were similar after heat stress, during infection of fish and mosquito larvae. The similarity also applies to some of the known heat shock genes such as the α-crystallin gene. Therefore, it seems probable that the physiological state of M. marinum is similar when exposed to these different conditions. Moreover, the mosquito larvae data suggest that this is the state that the fish encounter when infected, at least with respect to σ-factor mRNA levels. Comparative genomic analysis of σ-factor gene localizations in three M. marinum strains and Mycobacterium tuberculosis H37Rv revealed chromosomal rearrangements that changed the localization of especially sigA, sigB, sigD, sigE, sigF and sigJ after the divergence of these two species. This may explain the variation in species-specific expression upon exposure to different growth conditions.
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Pettersson BMF, Nitharwal RG, Das S, Behra KPR, Benedik E, Arasu UT, Islam NM, Dasgupta S, Bhattacharya A, Kirsebom LA. Identification and expression of stressosomal proteins in Mycobacterium marinum under various growth and stress conditions. FEMS Microbiol Lett 2013; 342:98-105. [PMID: 23480639 DOI: 10.1111/1574-6968.12118] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Revised: 03/02/2013] [Accepted: 03/04/2013] [Indexed: 11/27/2022] Open
Abstract
Like other bacteria, Mycobacterium spp. have developed different strategies in response to environmental changes such as nutrient limitations and other different stress situations. We have identified candidate genes (rsb genes) from Mycobacterium marinum involved in the regulation of the activity of the alternative sigma factor, σ(F) . This is a homolog of the master regulator of general stress response, σ(B) , and the sporulation-specific sigma factor, σ(F) , in Bacillus subtilis. The organization of these genes in M. marinum and B. subtilis is similar. Transcriptome and qRT-PCR data show that these genes are indeed expressed in M. marinum and that the levels of expression vary with growth phase and exposure to stress. In particular, cold stress caused a significant rise in the expression of all identified rsb and sigF genes. We discuss these data in relation to what is currently known for other Mycobacterium spp.
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Affiliation(s)
- B M Fredrik Pettersson
- Department of Cell and Molecular Biology, Biomedical Centre, Uppsala University, SE-751 24 Uppsala, Sweden
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Mycobacterial shuttle vectors designed for high-level protein expression in infected macrophages. Appl Environ Microbiol 2012; 78:6829-37. [PMID: 22820329 DOI: 10.1128/aem.01674-12] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mycobacterial shuttle vectors contain dual origins of replication for growth in both Escherichia coli and mycobacteria. One such vector, pSUM36, was re-engineered for high-level protein expression in diverse bacterial species. The modified vector (pSUM-kan-MCS2) enabled green fluorescent protein expression in E. coli, Mycobacterium smegmatis, and M. avium at levels up to 50-fold higher than that detected with the parental vector, which was originally developed with a lacZα promoter. This high-level fluorescent protein expression allowed easy visualization of M. smegmatis and M. avium in infected macrophages. The M. tuberculosis gene esat-6 was cloned in place of the green fluorescence protein gene (gfp) to determine the impact of ESAT-6 on the innate inflammatory response. The modified vector (pSUM-kan-MCS2) yielded high levels of ESAT-6 expression in M. smegmatis. The ability of ESAT-6 to suppress innate inflammatory pathways was assayed with a novel macrophage reporter cell line, designed with an interleukin-6 (IL-6) promoter-driven GFP cassette. This stable cell line fluoresces in response to diverse mycobacterial strains and stimuli, such as lipopolysaccharide. M. smegmatis clones expressing high levels of ESAT-6 failed to attenuate IL-6-driven GFP expression. Pure ESAT-6, produced in E. coli, was insufficient to suppress a strong inflammatory response elicited by M. smegmatis or lipopolysaccharide, with ESAT-6 itself directly activating the IL-6 pathway. In summary, a pSUM-protein expression vector and a mammalian IL-6 reporter cell line provide new tools for understanding the pathogenic mechanisms deployed by various mycobacterial species.
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The Mycobacterium tuberculosis SecA2 system subverts phagosome maturation to promote growth in macrophages. Infect Immun 2012; 80:996-1006. [PMID: 22215736 DOI: 10.1128/iai.05987-11] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The ability of Mycobacterium tuberculosis to grow in macrophages is critical to the virulence of this important pathogen. One way M. tuberculosis is thought to maintain a hospitable niche in macrophages is by arresting the normal process of phagosomes maturing into acidified phagolysosomes. The process of phagosome maturation arrest by M. tuberculosis is not fully understood, and there has remained a need to firmly establish a requirement for phagosome maturation arrest for M. tuberculosis growth in macrophages. Other intracellular pathogens that control the phagosomal environment use specialized protein export systems to deliver effectors of phagosome trafficking to the host cell. In M. tuberculosis, the accessory SecA2 system is a specialized protein export system that is required for intracellular growth in macrophages. In studying the importance of the SecA2 system in macrophages, we discovered that SecA2 is required for phagosome maturation arrest. Shortly after infection, phagosomes containing a ΔsecA2 mutant of M. tuberculosis were more acidified and showed greater association with markers of late endosomes than phagosomes containing wild-type M. tuberculosis. We further showed that inhibitors of phagosome acidification rescued the intracellular growth defect of the ΔsecA2 mutant, which demonstrated that the phagosome maturation arrest defect of the ΔsecA2 mutant is responsible for the intracellular growth defect. This study demonstrates the importance of phagosome maturation arrest for M. tuberculosis growth in macrophages, and it suggests there are effectors of phagosome maturation that are exported into the host environment by the accessory SecA2 system.
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Fieber LA, Tanguay RL, Walter RB, Williams DE. Aquatic animal models of human disease: selected papers from the 5th conference. Comp Biochem Physiol C Toxicol Pharmacol 2012; 155:9-10. [PMID: 21729766 DOI: 10.1016/j.cbpc.2011.06.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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