Prolyl hydroxylase 3 (PHD3) is essential for hypoxic regulation of neutrophilic inflammation in humans and mice
Sarah R. Walmsley, … , Peter Carmeliet, Moira K.B. Whyte
Sarah R. Walmsley, … , Peter Carmeliet, Moira K.B. Whyte
Published February 7, 2011
Citation Information: J Clin Invest. 2011;121(3):1053-1063. https://doi.org/10.1172/JCI43273.
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Research Article Inflammation

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

Sarah R. Walmsley, Edwin R. Chilvers, Alfred A. Thompson, Kathryn Vaughan, Helen M. Marriott, Lisa C. Parker, Gary Shaw, Selina Parmar, Martin Schneider, Ian Sabroe, David H. Dockrell, Marta Milo, Cormac T. Taylor, Randall S. Johnson, Christopher W. Pugh, Peter J. Ratcliffe, Patrick H. Maxwell, Peter Carmeliet, Moira K.B. Whyte

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Figure 5

Enhanced resolution of neutrophilic inflammation in Phd3–/– animals in hypoxia.

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Enhanced resolution of neutrophilic inflammation in Phd3–/– animals in h...
(A–I) Acute lung injury was induced by intratracheal LPS installation. Six hours after LPS, animals were recovered in environmental normoxia (21%) or hypoxia (10%) for 18 hours. BAL samples were assessed for total cell counts (A and E), total neutrophil counts (B and F), percent morphological neutrophil apoptosis (C and G), and percent TUNEL-positive PMNs (D and H) in WT (white bars) versus Phd3-null (black bars) mice for both normoxic recovery (A–D) and hypoxic recovery (E–H) (n = 9). (I) Animals were sacrificed at 18 hours, lungs fixed with 10% buffered formalin and paraffin-embedded, and sections stained with hematoxylin and eosin; original magnification, ×400. (J) Acute lung injury was induced by nebulized LPS and BAL samples assessed at 6 hours for total cell and neutrophil differential counts in WT (white bars) versus Phd3-null (black bars) mice (n = 4). (K) Bcl-xL and Siva1 expression by inflammatory cells. Serial paraffin-embedded sections from hypoxia-recovered mice were stained for expression of the neutrophil marker MPO, Bcl-xL, and Siva1, and individual MPO-positive matched cells are indicated by arrows; original magnification, ×400.