Department of Vascular Cell Biology, Max-Planck-Institute of Molecular Biomedicine, Münster, North Rhine-Westphalia, Germany.
Curr Opin Hematol. 2012 May;19(3):212-7. doi: 10.1097/MOH.0b013e3283523e78.
Leukocyte extravasation is a multistep process that is regulated at various levels. This review will highlight recent findings that define new regulatory mechanisms and novel activities in the process of leukocyte docking to the endothelium and diapedesis of leukocytes through the endothelial barrier of the vessel wall.
Within the past 2-3 years, novel regulatory mechanisms have been identified that control or balance leukocyte extravasation at different steps of the extravasation process. First evidence was established for differences in the roles of intracellular factors that bind to integrins and support their activation. A cytokine was found that counteracts the activation of leukocyte integrins. Not only leukocyte integrins but also their ligands on endothelial cells were shown to arrange in clusters while supporting leukocyte-endothelial interactions. Recent progress was made in determining in vivo the route of leukocyte diapedesis through the endothelium of the blood vessel wall. Finally, novel mechanisms were found that control the opening of the endothelial barrier during diapedesis and others that determine directionality of diapedesis.
Recent progress in our understanding of leukocyte extravasation has unraveled novel steps and mechanisms that control this process in vivo. These findings provide new insights into the mechanisms that balance the entry of leukocytes into tissue.
白细胞渗出是一个多步骤的过程，在多个水平受到调控。这篇综述将重点介绍最近的发现，这些发现定义了白细胞与内皮细胞附着和通过血管壁内皮屏障渗出的过程中的新调控机制和新活性。
在过去的 2-3 年中，已经确定了新的调控机制，这些机制可以控制或平衡白细胞渗出过程中不同步骤的白细胞渗出。首先，有证据表明，结合整合素并支持其激活的细胞内因子在作用上存在差异。发现了一种细胞因子，它可以对抗白细胞整合素的激活。不仅白细胞整合素，而且它们在血管内皮细胞上的配体也被证明在支持白细胞-内皮细胞相互作用的同时形成簇。最近在确定白细胞通过血管壁内皮渗出的体内途径方面取得了进展。最后，发现了控制渗出过程中内皮屏障开放的新机制以及决定渗出方向性的其他机制。
我们对白细胞渗出的理解的最新进展揭示了控制体内这一过程的新步骤和机制。这些发现为平衡白细胞进入组织的机制提供了新的见解。
