title: Neutrophil cannibalism triggers transforming growth factor β1 production and self regulation of neutrophil inflammatory function in monosodium urate monohydrate crystal-induced inflammation in mice.
abstract: OBJECTIVE
  To identify macrophage-independent sources of transforming growth factor β1 (TGFβ1) production during monosodium urate monohydrate (MSU) crystal-induced inflammation and to determine how TGFβ1 alters MSU crystal-recruited neutrophil functions.
  
  
  METHODS
  C57BL/6J mice were injected intraperitoneally with MSU crystals with or without TGFβ1-neutralizing antibody. MSU crystal-recruited peritoneal and blood neutrophils were purified and cultured ex vivo. Peritoneal neutrophils were treated with the caspase inhibitor Q-VD-OPh, anti-TGFβ1 antibody, or fluorochrome-labeled apoptotic neutrophils. Neutrophils were analyzed for expression of annexin V, caspase 3, and TGFβ1 by flow cytometry or fluorescence microscopy, for superoxide production using the redox-sensitive dye water-soluble tetrazolium 1, and for TGFβ1 and interleukin-1β (IL-1β) production by enzyme-linked immunosorbent assay.
  
  
  RESULTS
  Eighteen hours after MSU crystal administration in vivo, TGFβ1 levels were elevated in peritoneal lavage fluids, and a significant number of peritoneal neutrophils were TGFβ1+. Purified blood or peritoneal neutrophils cultured ex vivo showed TGFβ1+ neutrophils coexpressing the apoptosis marker caspase 3 and increased TGFβ1 production, both of which dropped following inhibition of apoptosis. Live neutrophils that had phagocytosed apoptotic neutrophils showed greatest TGFβ1 expression. Superoxide production by purified MSU crystal-recruited neutrophils ex vivo was enhanced by anti-TGFβ1 antibody treatment. Neutrophils purified from the peritoneum of MSU crystal-challenged mice treated with anti-TGFβ1 antibody produced elevated levels of superoxide, but neutrophil IL-1β production was unaffected.
  
  
  CONCLUSIONS
  Neutrophil cannibalism and TGFβ1 production have the potential to make a significant contribution to the controlled resolution of neutrophil-driven inflammatory diseases such as gout.
authors.affiliation: Malaghan Institute of Medical Research, Wellington, New Zealand.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Steiger
authors.forename: Jacquie L
authors.initials: JL
authors.lastname: Harper
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000737:chemistry / Q000633:toxicity; D017209:Apoptosis / Q000276:immunology; D002478:Cells, Cultured; D003460:Crystallization; D057899:Cytophagocytosis / Q000276:immunology*; D004195:Disease Models, Animal; D006073:Gout / Q000139:chemically induced / Q000276:immunology* / Q000473:pathology; D007249:Inflammation / Q000139:chemically induced / Q000276:immunology / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009504:Neutrophils / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D010529:Peritoneal Cavity / Q000166:cytology; D016897:Respiratory Burst / Q000276:immunology; D053773:Transforming Growth Factor beta1 / Q000276:immunology / Q000378:metabolism*; D014527:Uric Acid / Q000737:chemistry / Q000633:toxicity*
chemical_list: D000975:Antioxidants; D053773:Transforming Growth Factor beta1; D014527:Uric Acid