Mycobacterium avium MAV_2941 mimics phosphoinositol-3-kinase to interfere with macrophage phagosome maturation

Danelishvili, Lia; Bermudez, Luiz E.

doi:10.1016/j.micinf.2015.05.005

Cited by 20 publications

(27 citation statements)

References 37 publications

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“…MAV_2941 protein interacts with host proteins and interferes with normal phagosome maturation. Mutations in MAV_2941 were associated with impairment of growth in THP-1 macrophages [116].…”

Section: Phagosome Maturationmentioning

confidence: 98%

Molecular basis of mycobacterial survival in macrophages

Awuh

Flo

2016

Cell. Mol. Life Sci.

113

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Macrophages play an essential role in the immune system by ingesting and degrading invading pathogens, initiating an inflammatory response and instructing adaptive immune cells, and resolving inflammation to restore homeostasis. More interesting is the fact that some bacteria have evolved to use macrophages as a natural habitat and tools of spread in the host, e.g., Mycobacterium tuberculosis (Mtb) and some non-tuberculous mycobacteria (NTM). Mtb is considered one of humanity's most successful pathogens and is the causal agent of tuberculosis, while NTMs cause opportunistic infections all of which are of significant public health concern. Here, we describe mechanisms by which intracellular pathogens, with an emphasis on mycobacteria, manipulate macrophage functions to circumvent killing and live inside these cells even under considerable immunological pressure. Such macrophage functions include the selective evasion or engagement of pattern recognition receptors, production of cytokines, reactive oxygen and nitrogen species, phagosome maturation, as well as other killing mechanisms like autophagy and cell death. A clear understanding of host responses elicited by a specific pathogen and strategies employed by the microbe to evade or exploit these is of significant importance for the development of effective vaccines and targeted immunotherapy against persistent intracellular infections like tuberculosis.

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“…MAV_2941 protein interacts with host proteins and interferes with normal phagosome maturation. Mutations in MAV_2941 were associated with impairment of growth in THP-1 macrophages [116].…”

Section: Phagosome Maturationmentioning

confidence: 98%

Molecular basis of mycobacterial survival in macrophages

Awuh

Flo

2016

Cell. Mol. Life Sci.

113

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“…Phagosomes of M.avium in macrophages are initially large, but segment and split in one bacterium, one phagosome after hours following phagocytosis [4]. Virulent mycobacteria inhibit phagosome acidification [1, 4, 5]. In this study, we utilized an in vitro system that mimics the concentrations of single metals in the phagosome of M. avium infected macrophages [10].…”

Section: Discussionmentioning

confidence: 99%

“…Like Mycobacterium tuberculosis , M. avium survives and replicates within macrophages by blocking phagosome maturation and the fusion between the phagosome and lysosome [4], but many steps and mechanisms involved are still incompletely understood. The pathogen affects the transport of acid into the phagosome, as well as directly interferes with the trafficking of molecules associated with phagosome maturation in the cytosol [5]. …”

Section: Introductionmentioning

confidence: 99%

“…Many intracellular pathogens such as M. tuberculosis , Legionella, Coxiella, Salmonella and others, have been shown to depend on secreted molecules to control their environment inside the host for survival and replication [12–15]. There is substantial evidence that M. avium interferes with the macrophage function from inside of the vacuole [5, 16], and the expression of proteins on the bacterial surface or the export of effectors into the vacuole and/or the cytoplasm is manner to interact with the phagocyte.…”

Section: Introductionmentioning

confidence: 99%

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Identification of Mycobacterium avium subsp. hominissuis secreted proteins using an in vitro system mimicking the phagosomal environment

et al. 2016

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Background Mycobacterium avium subsp. hominissuis is a common intracellular pathogen that infects patients with HIV/AIDS and cause lung infection in patients with underlying lung pathology. M.avium preferably infects macrophages and uses diverse mechanisms to alter phagosome maturation. Once in the macrophage, the pathogen can alter the host cellular defenses by secreting proteins into the cytosol of host cells, but despite considerable research, only a few secreted effector proteins have been identified. We hypothesized that the environmental cues inside the phagosome can trigger bacterial protein secretion. To identify M. avium secretome within the phagosome, we utilized a previously established in vitro system that mimics the metal ion concentrations and pH of the M. avium phagosome.Results M. avium was exposed to phagosome metal concentrations for different time points and exported proteins were profiled and analyzed against bacterial proteins secreted in the culture medium. Mass spectrometric analysis of the secreted proteome identified several proteins, of which 46 were unique to bacteria incubated in the metal mixture. Ten of potential effectors were selected and secretion of these proteins was monitored within M. avium infected mononuclear phagocytic cells using the beta-lactamase FRET-based reporter system. In addition, pull-down assay was performed for secreted calmodulin-like protein MAV_1356 protein to evaluate for eukaryotic target. All examined M. avium proteins were secreted into the macrophage cytosol, and gene expression analysis suggested that the metal environment likely stimulates secretion of pre-made proteins. Further investigation of bacterial secreted MAV_1356 protein, lead to the observation that the MAV_1356 interacts with the host proteins Annexin A1 and Protein S100-A8.ConclusionsWe established an in vitro system for the study if proteins secreted intracellularly, and revealed that the metal mixture mimicking the concentration of metals in the phagosome environment, triggers protein secretion.

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“…Microbial killing not only depends on the toxic cellular environment but also on the scarcity of nutrients in the phagosomal compartment that M. avium occupies. Despite all, the pathogen actively prevents the vacuole acidification as well as the influx of many toxic compounds into the phagosome by blocking its fusion with late endosomes and lysosomes [7], and hijacks intracellular trafficking pathways to prevent destruction by macrophages [8,9]. M. avium is capable to resist to autophagic killing by phagocytic cells [10] and avoids effects of toxic products such as superoxide anion, nitric oxide, and bactericidal peptides such as cathelicidin and defensins [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Mycobacterium avium subsp. hominissuis effector MAVA5_06970 promotes rapid apoptosis in secondary-infected macrophages during cell-to-cell spread

et al. 2018

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Mycobacterium avium subsp. hominissuis is an opportunistic intracellular pathogen associated with disease in patients either immunosuppression or chronic lung pathology. Once in the host, M. avium preferentially infects and replicates within the phagocytic cells. The host driven macrophage apoptosis appears to be an essential aspect of innate immunity during bacterial infection; however, the existing evidence suggests that M. avium has evolved adaptive approaches to trigger the phagocyte apoptosis, exit apoptotic cells or via ingestion of infected apoptotic bodies subsequently infect neighboring macrophages. By evaluating 4,000 transposon mutants of M. avium in THP-1 cells, we identified clones that can trigger a new form of early host cell apoptosis, which is only observed upon entry into the “secondary-infected” macrophages. Inactivation of MAVA5_06970 gene lead to significant attenuation in intracellular growth within macrophages and mice, and impaired M. avium to induce rapid apoptosis in the “secondary-infected” cells as measured by Annexin V-FITC detection assay. Complementation of MAVA5_06970 gene corrected the attenuation as well as apoptotic phenotypes. The MAVA5_06970 gene encodes for a secreted protein. Using the pull-down assay and then confirmed with the yeast two-hybrid screen, we found that MAVA5_06970 effector interacts with the Secreted Phosphoprotein 1, the cytokine also known as Osteopontin. This interaction enhances the THP-1 cell apoptosis and, consequently, restricts the production of interleukin-12 that likely may limit the activation of the type I immunity pathway in vivo. This work identified a key virulence effector of M. avium that contributes to the cell-to-cell spread of the pathogen.

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Mycobacterium avium MAV_2941 mimics phosphoinositol-3-kinase to interfere with macrophage phagosome maturation

Cited by 20 publications

References 37 publications

Molecular basis of mycobacterial survival in macrophages

Molecular basis of mycobacterial survival in macrophages

Identification of Mycobacterium avium subsp. hominissuis secreted proteins using an in vitro system mimicking the phagosomal environment

Mycobacterium avium subsp. hominissuis effector MAVA5_06970 promotes rapid apoptosis in secondary-infected macrophages during cell-to-cell spread

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