Eash Kyle J, Means Jacquelyn M, White Douglas W, Link Daniel C
Department of Medicine, Divisions of Oncology, Washington University School of Medicine, St Louis, MO, USA.
Blood. 2009 May 7;113(19):4711-9. doi: 10.1182/blood-2008-09-177287. Epub 2009 Mar 5.
The number of neutrophils in the blood is tightly regulated to ensure adequate protection against microbial pathogens while minimizing damage to host tissue. Neutrophil homeostasis in the blood is achieved through a balance of neutrophil production, release from the bone marrow, and clearance from the circulation. Accumulating evidence suggests that signaling by CXCL12, through its major receptor CXCR4, plays a key role in maintaining neutrophil homeostasis. Herein, we generated mice with a myeloid lineage-restricted deletion of CXCR4 to define the mechanisms by which CXCR4 signals regulate this process. We show that CXCR4 negatively regulates neutrophil release from the bone marrow in a cell-autonomous fashion. However, CXCR4 is dispensable for neutrophil clearance from the circulation. Neutrophil mobilization responses to granulocyte colony-stimulating factor (G-CSF), CXCL2, or Listeria monocytogenes infection are absent or impaired, suggesting that disruption of CXCR4 signaling may be a common step mediating neutrophil release. Collectively, these data suggest that CXCR4 signaling maintains neutrophil homeostasis in the blood under both basal and stress granulopoiesis conditions primarily by regulating neutrophil release from the bone marrow.
血液中中性粒细胞的数量受到严格调控,以确保在对微生物病原体提供充分保护的同时,将对宿主组织的损伤降至最低。血液中的中性粒细胞稳态是通过中性粒细胞生成、从骨髓释放以及从循环中清除之间的平衡来实现的。越来越多的证据表明,CXCL12通过其主要受体CXCR4发出的信号在维持中性粒细胞稳态中起关键作用。在此,我们构建了CXCR4在髓系谱系中特异性缺失的小鼠,以确定CXCR4信号调节这一过程的机制。我们发现,CXCR4以细胞自主方式负向调节中性粒细胞从骨髓的释放。然而,CXCR4对于中性粒细胞从循环中的清除是可有可无的。对粒细胞集落刺激因子(G-CSF)、CXCL2或单核细胞增生李斯特菌感染的中性粒细胞动员反应缺失或受损,这表明CXCR4信号的破坏可能是介导中性粒细胞释放的一个共同步骤。总体而言,这些数据表明,CXCR4信号主要通过调节中性粒细胞从骨髓的释放,在基础和应激粒细胞生成条件下维持血液中的中性粒细胞稳态。