Extracellular Vesicles of Mycobacterium tuberculosis Serve as a Virulence Factor - Current Research Applications

Exosomes, microvesicles, and apoptotic bodies are types of extracellular vesicles (EVs), which are small, cup-shaped structures made up of two layers that come from both healthy and diseased cells. They improve intercellular signal transmission by transporting proteins, lipids, and nucleic acids. Blood, urine, ascitic fluid, amniotic fluid, cerebrospinal fluid, and bronchoalveolar lavage fluid include extracellular vesicles. Consequently, this review aimed to analyze the extracellular vesicles and their substantial functions in mycobacteria, such as transporting macromolecules and disease pathogenesis. Extracellular vesicle lipids, along with proteins and nucleic acids, are potential markers for various diseases, including tuberculosis caused by Mycobacterium tuberculosis. The extracellular vesicles secreted by mycobacterium include Toll-like receptor 2 agonists such as lipoproteins and lipoarabinomannan. These agonists stimulate Toll-like receptor 2-dependent proinflammatory cytokine production in macrophages. Primarily, extracellular vesicles transfer lipoproteins between cells; these lipoproteins are responsible for virulence factors and are closely associated with the pathogenesis of tuberculosis. LprA and LprG, among others, are likely involved. Clinically, the extracellular vesicles play substantial roles, likely including the translocation of lipoarabinomannan to the mycobacterium cell membrane. This process is linked with the lysis of autophagosome-lysosome fusion; thus, mycobacteria can be present in a dormant state in macrophages. Therefore, extracellular vesicles play a substantial role in disease prognosis, and analysis of their functions along with microRNAs will lead to future research in the therapy and diagnosis of tuberculosis.