title: Bacillary replication and macrophage necrosis are determinants of neutrophil recruitment in tuberculosis.
abstract: We previously determined that burst size necrosis is the chief mode of mononuclear cell death in the lungs of mice with tuberculosis. The present study explored the link between infection-induced necrosis of mononuclear phagocytes and neutrophil accumulation in the lungs of mice challenged with one of four Mycobacterium tuberculosis strains of increasing virulence (RvΔphoPR mutant, H37Ra, H37Rv and Erdman). At all time points studied, Erdman produced the highest bacterial load and the highest proportion and number of M. tuberculosis-infected neutrophils. These parameters, and the proportion of TUNEL-positive cells, tracked with virulence across all strains tested. Differences in neutrophil infection were not reflected by levels of chemoattractant cytokines in bronchoalveolar lavage fluid, while interferon-γ (reported to suppress neutrophil trafficking to the lung in tuberculosis) was highest in Erdman-infected mice. Treating Erdman-infected mice with ethambutol decreased the proportion of mononuclear phagocytes with high bacterial burden and the ratio of infected neutrophils to infected mononuclear cells in a dose-dependent manner. We propose that faster replicating M. tuberculosis strains cause more necrosis which in turn promotes neutrophil recruitment. Neutrophils infected with M. tuberculosis constitute a biomarker for poorly controlled bacterial replication, infection-induced mononuclear cell death, and increased severity of immune pathology in tuberculosis.
authors: Department of Medicine, University of Massachusetts Medical School, Worcester, MA, USA.
authors: Teresa
authors: T
authors: Repasy
authors: Department of Medicine, University of Massachusetts Medical School, Worcester, MA, USA.
authors: Nuria
authors: N
authors: Martinez
authors: Department of Medicine, University of Massachusetts Medical School, Worcester, MA, USA.
authors: Jinhee
authors: J
authors: Lee
authors: Department of Medicine, University of Massachusetts Medical School, Worcester, MA, USA.
authors: Kim
authors: K
authors: West
authors: Division of Preventive and Behavioral Medicine, University of Massachusetts Medical School, Worcester, MA, USA.
authors: Wenjun
authors: W
authors: Li
authors: Department of Medicine, University of Massachusetts Medical School, Worcester, MA, USA. Electronic address: Hardy.Kornfeld@umassmed.edu.
authors: Hardy
authors: H
authors: Kornfeld
mesh_terms: D000818:Animals; D058491:Bacterial Load; D016923:Cell Death / Q000276:immunology; D051379:Mice; D009169:Mycobacterium tuberculosis / Q000276:immunology / Q000378:metabolism / Q000472:pathogenicity*; D020556:Neutrophil Infiltration / Q000276:immunology*; D009504:Neutrophils / Q000276:immunology* / Q000378:metabolism; D014376:Tuberculosis / Q000382:microbiology* / Q000473:pathology; D014774:Virulence / Q000276:immunology
keywords: Cell death; Macrophages; Neutrophils; Tuberculosis