Academic Unit of Respiratory Medicine, The Medical School, University of Sheffield, Sheffield, United Kingdom.
J Clin Invest. 2011 Mar;121(3):1053-63. doi: 10.1172/JCI43273. Epub 2011 Feb 7.
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.
诱导细胞凋亡来调节中性粒细胞寿命对于维持有效的宿主反应和防止过度炎症至关重要。缺氧诱导因子(HIF)氧感应途径对中性粒细胞凋亡的易感性有重大影响,在缺氧条件下观察到细胞死亡明显延迟。HIF 的表达和转录活性受氧敏感脯氨酰羟化酶(PHD1-3)调节,但 PHD 在中性粒细胞存活中的作用尚不清楚。我们检查了人中性粒细胞中的 PHD 表达,发现 PHD3 在体外和体内对缺氧和炎症刺激有强烈的诱导。使用 Phd3 缺陷的小鼠中性粒细胞,我们证明了 Phd3 在延长缺氧时中性粒细胞存活中的独特作用,与中性粒细胞功能和代谢活性的其他与缺氧相关的变化不同。此外,这种中性粒细胞存活的选择性缺陷发生在保持 HIF 转录活性的情况下,但与促凋亡介质 Siva1 的上调和其结合靶标 Bcl-xL 的丧失有关。在体内,使用急性肺损伤模型,我们观察到与 WT 对照相比,Phd3 缺陷小鼠的中性粒细胞凋亡和清除增加。我们还观察到在急性结肠炎小鼠模型中中性粒细胞炎症减少。这些数据支持我们认为 PHD3 在调节缺氧时中性粒细胞存活方面具有新的功能,并且可能为炎症性疾病开发新的治疗方法。