title: Pathogenic mycobacteria achieve cellular persistence by inhibiting the Niemann-Pick Type C disease cellular pathway.
abstract: BACKGROUND
  Tuberculosis remains a major global health concern. The ability to prevent phagosome-lysosome fusion is a key mechanism by which intracellular mycobacteria, includingMycobacterium tuberculosis, achieve long-term persistence within host cells. The mechanisms underpinning this key intracellular pro-survival strategy remain incompletely understood. Host macrophages infected with persistent mycobacteria share phenotypic similarities with cells taken from patients suffering from Niemann-Pick Disease Type C (NPC), a rare lysosomal storage disease in which endocytic trafficking defects and lipid accumulation within the lysosome lead to cell dysfunction and cell death. We investigated whether these shared phenotypes reflected an underlying mechanistic connection between mycobacterial intracellular persistence and the host cell pathway dysfunctional in NPC.
  
  
  METHODS
  The induction of NPC phenotypes in macrophages from wild-type mice or obtained from healthy human donors was assessed via infection with mycobacteria and subsequent measurement of lipid levels and intracellular calcium homeostasis. The effect of NPC therapeutics on intracellular mycobacterial load was also assessed.
  
  
  RESULTS
  Macrophages infected with persistent intracellular mycobacteria phenocopied NPC cells, exhibiting accumulation of multiple lipid types, reduced lysosomal Ca2+levels, and defects in intracellular trafficking. These NPC phenotypes could also be induced using only lipids/glycomycolates from the mycobacterial cell wall. These data suggest that persistent intracellular mycobacteria inhibit the NPC pathway, likely via inhibition of the NPC1 protein, and subsequently induce altered acidic store Ca2+homeostasis. Reduced lysosomal calcium levels may provide a mechanistic explanation for the reduced levels of phagosome-lysosome fusion in mycobacterial infection. Treatments capable of correcting defects in NPC mutant cells via modulation of host cell calcium were of benefit in promoting clearance of mycobacteria from infected host cells.
  
  
  CONCLUSIONS
  These findings provide a novel mechanistic explanation for mycobacterial intracellular persistence, and suggest that targeting interactions between the mycobacteria and host cell pathways may provide a novel avenue for development of anti-TB therapies.
authors.affiliation: Department of Pharmacology, University of Oxford, Oxford, UK.
authors.forename: Paul
authors.initials: P
authors.lastname: Fineran
authors.affiliation: Department of Pharmacology, University of Oxford, Oxford, UK.|School of Biosciences, Cardiff University, Cardiff, UK.
authors.forename: Emyr
authors.initials: E
authors.lastname: Lloyd-Evans
authors.affiliation: Department of Pharmacology, University of Oxford, Oxford, UK.|School of Medicine, Koç University, Istanbul, Turkey.
authors.forename: Nathan A
authors.initials: NA
authors.lastname: Lack
authors.affiliation: Department of Pharmacology, University of Oxford, Oxford, UK.
authors.forename: Nick
authors.initials: N
authors.lastname: Platt
authors.affiliation: Department of Pharmacology, University of Oxford, Oxford, UK.
authors.forename: Lianne C
authors.initials: LC
authors.lastname: Davis
authors.affiliation: Department of Pharmacology, University of Oxford, Oxford, UK.
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Morgan
authors.affiliation: Department of Pharmacology, University of Oxford, Oxford, UK.
authors.forename: Doris
authors.identifier: 0000-0002-6862-0076
authors.initials: D
authors.lastname: Höglinger
authors.affiliation: Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, USA.
authors.forename: Raju Venkata V
authors.initials: RVV
authors.lastname: Tatituri
authors.affiliation: Public Health England, Salisbury, UK.
authors.forename: Simon
authors.initials: S
authors.lastname: Clark
authors.affiliation: Department of Pharmacology, University of Oxford, Oxford, UK.
authors.forename: Ian M
authors.initials: IM
authors.lastname: Williams
authors.affiliation: Department of Pharmacology, University of Oxford, Oxford, UK.
authors.forename: Patricia
authors.initials: P
authors.lastname: Tynan
authors.affiliation: Department of Pharmacology, University of Oxford, Oxford, UK.
authors.forename: Nada
authors.initials: N
authors.lastname: Al Eisa
authors.affiliation: Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, USA.
authors.forename: Evgeniya
authors.initials: E
authors.lastname: Nazarova
authors.affiliation: Public Health England, Salisbury, UK.
authors.forename: Ann
authors.initials: A
authors.lastname: Williams
authors.affiliation: Department of Pharmacology, University of Oxford, Oxford, UK.
authors.forename: Antony
authors.initials: A
authors.lastname: Galione
authors.affiliation: Diabetic Cardiovascular Disease Center, Washington University School of Medicine, St. Louis, USA.
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Ory
authors.affiliation: School of Biosciences, University of Birmingham, Birmingham, UK.
authors.forename: Gurdyal S
authors.initials: GS
authors.lastname: Besra
authors.affiliation: Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, USA.
authors.forename: David G
authors.initials: DG
authors.lastname: Russell
authors.affiliation: Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, USA.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Brenner
authors.affiliation: Department of Pharmacology, University of Oxford, Oxford, UK.|Faculty of Science Engineering and Computing, Kingston University, Kingston upon Thames, UK.
authors.forename: Edith
authors.initials: E
authors.lastname: Sim
authors.affiliation: Department of Pharmacology, University of Oxford, Oxford, UK.
authors.forename: Frances M
authors.identifier: 0000-0001-7614-0403
authors.initials: FM
authors.lastname: Platt
keywords: Lysosomal Calcium; Lysosomal Storage Diseases; Niemann-Pick Disease Type C; Tuberculosis