title: Mycobacteria entry and trafficking into endothelial cells.
abstract: Endothelial cells are susceptible to infection by mycobacteria, but the endocytic mechanisms that mycobacteria exploit to enter host cells and their mechanisms of intracellular transport are completely unknown. Using pharmacological inhibitors, we determined that the internalization of Mycobacterium tuberculosis (MTB), Mycobacterium smegmatis (MSM), and Mycobacterium abscessus (MAB) is dependent on the cytoskeleton and is differentially inhibited by cytochalasin D, nocodazole, cycloheximide, wortmannin, and amiloride. Using confocal microscopy, we investigated their endosomal trafficking by analyzing Rab5, Rab7, LAMP-1, and cathepsin D. Our results suggest that MSM exploits macropinocytosis to enter endothelial cells and that the vacuoles containing these bacteria fuse with lysosomes. Conversely, the entry of MTB seems to depend on more than one endocytic route, and the observation that only a subset of the intracellular bacilli was associated with phagolysosomes suggests that these bacteria are able to inhibit endosomal maturation to persist intracellularly. The route of entry for MAB depends mainly on microtubules, which suggests that MAB uses a different trafficking pathway. However, MAB is also able to inhibit endosomal maturation and can replicate intracellularly. Together, these findings provide the first evidence that mycobacteria modulate proteins of host endothelial cells to enter and persist within these cells.
authors.affiliation: Department of Immunology, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Prolongación de Carpio y Plan de Ayala S/N, 11340 México, D.F., México.
authors.forename: Shantal Lizbeth
authors.initials: SL
authors.lastname: Baltierra-Uribe
authors.forename: Manuel de Jesús
authors.initials: Mde J
authors.lastname: García-Vásquez
authors.forename: Nayeli Shantal
authors.initials: NS
authors.lastname: Castrejón-Jiménez
authors.forename: Mayra Patricia
authors.initials: MP
authors.lastname: Estrella-Piñón
authors.forename: Julieta
authors.initials: J
authors.lastname: Luna-Herrera
authors.forename: Blanca Estela
authors.initials: BE
authors.lastname: García-Pérez
mesh_terms: D000584:Amiloride / Q000494:pharmacology; D000730:Androstadienes / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001692:Biological Transport; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D015638:Cytochalasin D / Q000494:pharmacology; D011992:Endosomes / Q000378:metabolism / Q000382:microbiology; D054884:Host-Pathogen Interactions; D061307:Human Umbilical Vein Endothelial Cells / Q000187:drug effects / Q000378:metabolism / Q000382:microbiology*; D006801:Humans; D050296:Microbial Viability; D018613:Microscopy, Confocal; D009161:Mycobacterium / Q000502:physiology*; D015739:Nocodazole / Q000494:pharmacology; D010588:Phagosomes / Q000378:metabolism / Q000382:microbiology; D014617:Vacuoles / Q000382:microbiology; D000077191:Wortmannin
chemical_list: D000730:Androstadienes; D000900:Anti-Bacterial Agents; D015638:Cytochalasin D; D000584:Amiloride; D003513:Cycloheximide; D015739:Nocodazole; D000077191:Wortmannin
keywords: Mycobacterium abscessus; Mycobacterium tuberculosis; Rab proteins; cellules endothéliales; endothelial cells; macropinocytose; macropinocytosis; protéines Rab