Molecular Biology Institute, University of California, Los Angeles.
Department of Cell and Developmental Biology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA.
Curr Opin Hematol. 2020 May;27(3):181-189. doi: 10.1097/MOH.0000000000000573.
The well recognized plasticity and diversity, typical of monocytes and macrophages have recently been expanded by the knowledge that additional macrophage lineages originated directly from embryonic progenitors, populate and establish residency in all tissues examined so far. This review aims to summarize our current understanding on the diversity of monocyte/macrophage subtypes associated with the vasculature, their specific origins, and nature of their cross-talk with the endothelium.
Taking stock of the many interactions between the endothelium and monocytes/macrophages reveals a far more intricate and ever-growing depth. In addition to circulating and surveilling the endothelium, monocytes can specifically be differentiated into patrolling cells that crawl on the surface of the endothelium and promote homeostasis. The conversion of classical to patrolling is endothelium-dependent uncovering an important functional link. In addition to patrolling cells, the endothelium also recruits and harbor an intimal-resident myeloid population that resides in the tunica intima in the absence of pathological insults. Moreover, the adventitia is populated with resident macrophages that support blood vessel integrity and prevent fibrosis.
The last few years have witnessed a significant expansion in our knowledge of the many subtypes of monocytes and macrophages and their corresponding functional interactions with the vascular wall. In addition to surveying the endothelium for opportunities of diapedeses, monocyte and macrophages take residence in both the intima (as patrolling or resident) and in the adventitia. Their contributions to vascular function are broad and critical to homeostasis, regeneration, and expansion.
单核细胞和巨噬细胞具有公认的可塑性和多样性，最近的研究发现，除了源自胚胎前体细胞的其他巨噬细胞谱系之外，这些细胞还可以直接定位于所有迄今为止检查过的组织中，并定居下来。本综述旨在总结我们目前对与脉管系统相关的单核细胞/巨噬细胞亚型的多样性、其特定起源以及它们与内皮细胞相互作用的性质的理解。
盘点内皮细胞与单核细胞/巨噬细胞之间的许多相互作用，揭示了一个更加复杂和不断发展的深度。除了循环和监测内皮细胞外，单核细胞还可以特化为巡逻细胞，在内皮细胞表面爬行并促进稳态。经典向巡逻的转化依赖于内皮细胞，揭示了一个重要的功能联系。除了巡逻细胞，内皮细胞还招募并容纳了一个内在的髓样细胞群体，在没有病理损伤的情况下，它存在于内膜中。此外，外膜中还存在支持血管完整性和防止纤维化的固有巨噬细胞。
在过去的几年中，我们对单核细胞和巨噬细胞的许多亚型及其与血管壁的相应功能相互作用有了显著的了解。除了监测内皮细胞的渗出机会外，单核细胞和巨噬细胞还定位于内膜（作为巡逻或固有细胞）和外膜。它们对血管功能的贡献广泛而关键，对稳态、再生和扩张至关重要。
