Department of Pathology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA.
Department of Neurological Surgery and Malnati Brain Tumor Institute of the Lurie Comprehensive Cancer Center, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA.
J Clin Invest. 2023 Aug 1;133(15):e170733. doi: 10.1172/JCI170733.
Neutrophil (PMN) mobilization to sites of insult is critical for host defense and requires transendothelial migration (TEM). TEM involves several well-studied sequential adhesive interactions with vascular endothelial cells (ECs); however, what initiates or terminates this process is not well-understood. Here, we describe what we believe to be a new mechanism where vessel-associated macrophages through localized interactions primed EC responses to form ICAM-1 "hot spots" to support PMN TEM. Using real-time intravital microscopy of LPS-inflamed intestines in CX3CR1-EGFP macrophage-reporter mice, complemented by whole-mount tissue imaging and flow cytometry, we found that macrophage vessel association is critical for the initiation of PMN-EC adhesive interactions, PMN TEM, and subsequent accumulation in the intestinal mucosa. Anti-colony stimulating factor 1 receptor Ab-mediated macrophage depletion in the lamina propria and at the vessel wall resulted in elimination of ICAM-1 hot spots impeding PMN-EC interactions and TEM. Mechanistically, the use of human clinical specimens, TNF-α-KO macrophage chimeras, TNF-α/TNF receptor (TNF-α/TNFR) neutralization, and multicellular macrophage-EC-PMN cocultures revealed that macrophage-derived TNF-α and EC TNFR2 axis mediated this regulatory mechanism and was required for PMN TEM. As such, our findings identified clinically relevant mechanisms by which macrophages regulate PMN trafficking in inflamed mucosa.
中性粒细胞(PMN)向损伤部位的迁移对于宿主防御至关重要,需要穿过血管内皮细胞(EC)。TEM 涉及几个经过深入研究的与血管内皮细胞的连续黏附相互作用;然而,启动或终止这个过程的机制尚不清楚。在这里,我们描述了一个新的机制,即血管相关巨噬细胞通过局部相互作用,预先激活 EC 反应,形成 ICAM-1“热点”,以支持 PMN 的 TEM。我们使用 CX3CR1-EGFP 巨噬细胞报告小鼠的 LPS 诱导的肠组织实时活体显微镜检查,辅以全组织成像和流式细胞术,发现巨噬细胞与血管的关联对于 PMN-EC 黏附相互作用的启动、PMN 的 TEM 以及随后在肠黏膜中的积累至关重要。在固有层和血管壁中用抗集落刺激因子 1 受体 Ab 进行巨噬细胞耗竭会消除 ICAM-1 热点,从而阻碍 PMN-EC 相互作用和 TEM。从机制上讲,使用人类临床标本、TNF-α-KO 巨噬细胞嵌合体、TNF-α/TNF 受体(TNF-α/TNFR)中和以及多细胞巨噬细胞-EC-PMN 共培养揭示了巨噬细胞衍生的 TNF-α 和 EC TNFR2 轴介导了这种调节机制,并需要 PMN 的 TEM。因此,我们的发现确定了巨噬细胞在炎症黏膜中调节 PMN 迁移的临床相关机制。