title: Single-cell analysis of mast cell degranulation induced by airway smooth muscle-secreted chemokines.
abstract: BACKGROUND
  Asthma is a chronic inflammatory disease characterized by narrowed airways, bronchial hyper-responsiveness, mucus hyper-secretion, and airway remodeling. Mast cell (MC) infiltration into airway smooth muscle (ASM) is a defining feature of asthma, and ASM regulates the inflammatory response by secreting chemokines, including CXCL10 and CCL5. Single cell analysis offers a unique approach to study specific cellular signaling interactions within large and complex signaling networks such as the inflammatory microenvironment in asthma.
  
  
  METHODS
  Carbon-fiber microelectrode amperometry was used to study the effects of ASM-secreted chemokines on mouse peritoneal MC degranulation.
  
  
  RESULTS
  MC degranulation in response to CXCL10 and CCL5 was monitored at the single cell level. Relative to IgE-mediated degranulation, CXCL10- and CCL5-stimulated MCs released a decreased amount of serotonin per granule with fewer release events per cell. Decreased serotonin release per granule was correlated with increased spike half-width and rise-time values.
  
  
  CONCLUSIONS
  MCs are directly activated by ASM-associated chemokines. CXCL10 and CCL5 induce less robust MC degranulation compared to IgE- and A23187-stimulation. The kinetics of MC degranulation are signaling pathway-dependent, suggesting a biophysical mechanism of regulated degranulation that incorporates control over granule trafficking, transport, and docking machinery.
  
  
  CONCLUSIONS
  The biophysical mechanisms, including variations in number of exocytotic release events, serotonin released per granule, and the membrane kinetics of exocytosis that underlie MC degranulation in response to CXCL10 and CCL5 were characterized at the single cell level. These findings clarify the function of ASM-derived chemokines as instigators of MC degranulation relative to classical mechanisms of MC stimulation.
authors.affiliation: Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA.
authors.forename: Benjamin M
authors.initials: BM
authors.lastname: Manning
authors.affiliation: Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA.
authors.forename: Audrey F
authors.initials: AF
authors.lastname: Meyer
authors.affiliation: Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA.
authors.forename: Sarah M
authors.initials: SM
authors.lastname: Gruba
authors.affiliation: Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA. Electronic address: chaynes@umn.edu.
authors.forename: Christy L
authors.initials: CL
authors.lastname: Haynes
mesh_terms: D000818:Animals; D001980:Bronchi / Q000276:immunology*; D002244:Carbon; D000077482:Carbon Fiber; D015550:Cell Degranulation; D002478:Cells, Cultured; D018946:Chemokine CCL5 / Q000502:physiology; D054357:Chemokine CXCL10 / Q000502:physiology; D018925:Chemokines / Q000502:physiology*; D008407:Mast Cells / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008839:Microelectrodes; D009130:Muscle, Smooth / Q000276:immunology*; D012701:Serotonin / Q000378:metabolism; D059010:Single-Cell Analysis / Q000379:methods*
chemical_list: D000077482:Carbon Fiber; C503460:Ccl5 protein, mouse; D018946:Chemokine CCL5; D054357:Chemokine CXCL10; D018925:Chemokines; C485433:Cxcl10 protein, mouse; D012701:Serotonin; D002244:Carbon
keywords: Asthma; Carbon-fiber microelectrode amperometry; Exocytosis