Mycobacterial extracellular vesicles and host pathogen interactions

Abstract

Mycobacteria, like other bacteria, archaea and eukaryotic cells, naturally release extracellular vesicles (EVs) to interact with their environment. EVs produced by pathogenic bacteria are involved in many activities including cell–cell communication, immunomodulation, virulence and cell survival. Although EVs released by thick cell wall microorganisms like mycobacteria were recognized only recently, studies of Mycobacterium tuberculosis EVs already point to their important roles in host pathogen interactions, opening exciting new areas of investigation. This minireview will summarize the current understanding of mycobacterial EV biology and roles in pathogenesis and will discuss their potential therapeutic applications.

Mycobacterium marinum produces distinct mycobactin and carboxymycobactin siderophores to promote growth in broth and phagocytes

“…The watersoluble cMBT is released into the environment, where it retrieves Fe 3 + ions in soluble form or, in case of pathogenic mycobacteria, from iron-containing host proteins such as transferrin or lactoferrin (Sritharan, 2016;Chao et al, 2019). The lipophilic MBT localises to mycobacterial membranes and the cell wall and remains membrane/ cell wall-bound (Ratledge, Patel, & Mundy, 1982;Touchette & Seeliger, 2017), but can also be released in membrane vesicles (MVs) and thus might bind Fe 3+ beyond the immediate vicinity of the bacteria (Gupta & Rodriguez, 2018;Prados-Rosales et al, 2014).…”

Accuracy of the tuberculosis point-of-care Alere determine lipoarabinomannan antigen diagnostic test using α-mannosidase treated and untreated urine in a cohort of people living with HIV in Guatemala

“…4 Sección de Microbiología, Departamento de Laboratorios Clínicos, Hospital Roosevelt, Guatemala City, Guatemala. 5 Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA. 6 Clinica de Atención Integral Dr. Isaac Cohen Alcahé, Hospital de Especialidad Dr. Robles, Quetzaltenango, Guatemala.…”

“…Lipoarabinomannan (LAM) is a M. tuberculosis cell envelope lipoglycan that is being explored as a biomarker for active TB disease. LAM is a heterogeneous, stable, immunogenic, and virulent factor thought to be released into the milieu by active or degrading bacilli [5,6]. M. tuberculosis LAM is a tripartite structure composed of a lipid moiety [glycosyl-phosphatidyl-myo-inositol (GPI) anchor] with different degree of acylation by different fatty acids.…”

Characterization of Membrane Vesicles Released by Mycobacterium Avium in Response to Environment Mimicking the Macrophage Phagosome

“…To enrich our BONCAT results, protein secretion at early time points than 24 h should be investigated. Despite the fact that we need to experimentally validate if these effectors are exported across bacterial cell wall via release of MVs, there is a strong evidence suggesting that MVs released by M. tuberculosis within infected macrophages can escape phagosomes [22] and they play important role during host–pathogen interaction [62]. By examining the ability of extracellular MVs to cross the macrophage plasma membrane and by using inhibitors blocking several different uptake mechanisms, this study demonstrates that MVs are translocated via plasma membrane by clathrin-mediated endocytosis and over 48 h vesicles disintegrate in the cytosol.…”