title: Prolyl hydroxylase 3 (PHD3) is essential for hypoxic regulation of neutrophilic inflammation in humans and mice.
abstract: The regulation of neutrophil lifespan by induction of apoptosis is critical for maintaining an effective host response and preventing excessive inflammation. The hypoxia-inducible factor (HIF) oxygen-sensing pathway has a major effect on the susceptibility of neutrophils to apoptosis, with a marked delay in cell death observed under hypoxic conditions. HIF expression and transcriptional activity are regulated by the oxygen-sensitive prolyl hydroxylases (PHD1-3), but the role of PHDs in neutrophil survival is unclear. We examined PHD expression in human neutrophils and found that PHD3 was strongly induced in response to hypoxia and inflammatory stimuli in vitro and in vivo. Using neutrophils from mice deficient in Phd3, we demonstrated a unique role for Phd3 in prolonging neutrophil survival during hypoxia, distinct from other hypoxia-associated changes in neutrophil function and metabolic activity. Moreover, this selective defect in neutrophil survival occurred in the presence of preserved HIF transcriptional activity but was associated with upregulation of the proapoptotic mediator Siva1 and loss of its binding target Bcl-xL. In vivo, using an acute lung injury model, we observed increased levels of neutrophil apoptosis and clearance in Phd3-deficient mice compared with WT controls. We also observed reduced neutrophilic inflammation in an acute mouse model of colitis. These data support what we believe to be a novel function for PHD3 in regulating neutrophil survival in hypoxia and may enable the development of new therapeutics for inflammatory disease.
authors.affiliation: Academic Unit of Respiratory Medicine, The Medical School, University of Sheffield, Sheffield, United Kingdom. s.walmsley@sheffield.ac.uk
authors.forename: Sarah R
authors.initials: SR
authors.lastname: Walmsley
authors.forename: Edwin R
authors.initials: ER
authors.lastname: Chilvers
authors.forename: Alfred A
authors.initials: AA
authors.lastname: Thompson
authors.forename: Kathryn
authors.initials: K
authors.lastname: Vaughan
authors.forename: Helen M
authors.initials: HM
authors.lastname: Marriott
authors.forename: Lisa C
authors.initials: LC
authors.lastname: Parker
authors.forename: Gary
authors.initials: G
authors.lastname: Shaw
authors.forename: Selina
authors.initials: S
authors.lastname: Parmar
authors.forename: Martin
authors.initials: M
authors.lastname: Schneider
authors.forename: Ian
authors.initials: I
authors.lastname: Sabroe
authors.forename: David H
authors.initials: DH
authors.lastname: Dockrell
authors.forename: Marta
authors.initials: M
authors.lastname: Milo
authors.forename: Cormac T
authors.initials: CT
authors.lastname: Taylor
authors.forename: Randall S
authors.initials: RS
authors.lastname: Johnson
authors.forename: Christopher W
authors.initials: CW
authors.lastname: Pugh
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Ratcliffe
authors.forename: Patrick H
authors.initials: PH
authors.lastname: Maxwell
authors.forename: Peter
authors.initials: P
authors.lastname: Carmeliet
authors.forename: Moira K B
authors.initials: MK
authors.lastname: Whyte
mesh_terms: D000818:Animals; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins; D002470:Cell Survival; D049308:Dioxygenases / Q000502:physiology*; D006801:Humans; D000860:Hypoxia; D051793:Hypoxia-Inducible Factor 1 / Q000378:metabolism; D064799:Hypoxia-Inducible Factor-Proline Dioxygenases; D007249:Inflammation; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D007963:Leukocytes, Mononuclear / Q000166:cytology; D055370:Lung Injury / Q000473:pathology; D051379:Mice; D008822:Mice, Transgenic; D009504:Neutrophils / Q000166:cytology / Q000378:metabolism*; D011393:Procollagen-Proline Dioxygenase / Q000378:metabolism*; D051020:bcl-X Protein / Q000378:metabolism
chemical_list: D051017:Apoptosis Regulatory Proteins; D051793:Hypoxia-Inducible Factor 1; D047908:Intracellular Signaling Peptides and Proteins; C484569:Siva protein, mouse; D051020:bcl-X Protein; D049308:Dioxygenases; C522722:PHD3 protein, mouse; D011393:Procollagen-Proline Dioxygenase; C488894:EGLN3 protein, human; D064799:Hypoxia-Inducible Factor-Proline Dioxygenases