title: Mycobacterium tuberculosis-induced neutrophil ectosomes decrease macrophage activation.
abstract: BACKGROUND
  The existence of ectosome-like microvesicles released by neutrophils was proposed a few decades ago. Other studies revealed that the innate immune response during mycobacterial infection is accompanied by an intense migration of neutrophils to the site of infection, which may be important during the acute phase of tuberculosis. We found that the ectosomes derived from infected neutrophils are biologically active and can influence the survival of Mycobacterium tuberculosis within macrophages.
  
  
  METHODS
  Mycobacteria were cultured on supplemented Middlebrook-7H9 broth. All strains were grown to the exponential phase and quantitated by serial dilution. Human neutrophils and macrophages were infected with mycobacteria. Ectosomes from neutrophils were isolated post-infection and characterized by transmission electron microscopy and flow cytometry. To determine whether these microvesicles influenced mycobactericidal activity, mycobacteria-infected macrophages were treated with isolated ectosomes.
  
  
  RESULTS
  Ectosomes were released from neutrophils infected with mycobacteria. These ectosomes were derived from neutrophil plasma membrane and a small proportion stained with PKH26. These microvesicles, when incubated with infected macrophages, influenced antimycobacterial activity.
  
  
  CONCLUSIONS
  This is the first study to demonstrate that ectosomes that are shed from infected neutrophils influence mycobactericidal activity in macrophages in vitro, suggesting that these microvesicles have biological significance. Nevertheless, major gaps in our knowledge of microvesicle biology remain.
authors.affiliation: Health Science Institute, Federal University of Bahia, Salvador, BA, Brazil. tonya.duarte@gmail.com
authors.forename: Tonya Azevedo
authors.initials: TA
authors.lastname: Duarte
authors.forename: Alberto Augusto
authors.initials: AA
authors.lastname: Noronha-Dutra
authors.forename: Joilda Silva
authors.initials: JS
authors.lastname: Nery
authors.forename: Samantha Brum
authors.initials: SB
authors.lastname: Ribeiro
authors.forename: Thassila Nogueira
authors.initials: TN
authors.lastname: Pitanga
authors.forename: José R
authors.initials: JR
authors.lastname: Lapa E Silva
authors.forename: Sérgio
authors.initials: S
authors.lastname: Arruda
authors.forename: Neio
authors.initials: N
authors.lastname: Boéchat
mesh_terms: D002450:Cell Communication / Q000276:immunology; D055252:Cell-Derived Microparticles / Q000276:immunology* / Q000648:ultrastructure; D002478:Cells, Cultured; D005456:Fluorescent Dyes; D006801:Humans; D008262:Macrophage Activation / Q000276:immunology*; D008264:Macrophages / Q000276:immunology / Q000382:microbiology; D008854:Microscopy, Electron; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D009504:Neutrophils / Q000276:immunology* / Q000382:microbiology / Q000648:ultrastructure; D009930:Organic Chemicals; D014376:Tuberculosis / Q000276:immunology*
chemical_list: D005456:Fluorescent Dyes; D009930:Organic Chemicals; C070080:PKH 26