Division of Nephrology, Department of Medicine, University of Virginia, Charlottesville, Virginia, USA.
Center for Immunity, Inflammation, and Regenerative Medicine, Department of Medicine, University of Virginia, Charlottesville, Virginia, USA.
Nephron. 2023;147(1):39-43. doi: 10.1159/000526266. Epub 2022 Sep 15.
Myeloid cells form an important element of the response to ischemia-reperfusion injury (IRI). While the mononuclear phagocyte system is complex and difficult to study, our knowledge of the cells involved and their impacts has been steadily increasing. However, there is still need to rigorously define and separate the functions of discreet myeloid populations in the kidney. The relatively recent distinction between resident macrophages and infiltrating monocytes in the kidney is an important advance that will enhance our understanding of the various roles of distinct myeloid populations, but specific tools are needed to rigorously define the contributions of each to injury, repair, and the transition to chronic disease.
Resident macrophages in the kidney form a network with various supportive roles during development and homeostasis. While the classification of these cells has been frequently convoluted in the literature, evidence for their roles during injury and repair is starting to accumulate. Current indications suggest they may have a minimal role during injury processes but may be important during the recovery phase. However, their involvement may also be dependent on their activation state in response to environmental cues. Investigations of the M1/M2 phenotype of myeloid cells have shed some light on the phenotypes that contribute to the manifestation of injury and/or recovery, but it is still difficult to form detailed conclusions. Here we will discuss the potential involvement of resident cells in these processes and the use of the M1/M2 system for defining the myeloid response following IRI.
There is a need for additional specific analysis of the contribution of resident versus recruited myeloid cells to injury, recovery, and chronic disease in the kidney. In addition, the contribution of myeloid activation states that extend beyond simple M1/M2 classification is an important area that needs close attention. Our ability to assess resident cells is growing, and awareness of the shortcoming of the M1/M2 system is also increasing. These are promising developments which bode well for the future of kidney injury and disease research.
髓样细胞是缺血再灌注损伤（IRI）反应的重要组成部分。单核吞噬细胞系统复杂且难以研究，但是我们对其中涉及的细胞及其影响的了解一直在稳步增加。然而，仍需要严格定义和分离肾脏中离散髓样细胞群体的功能。肾脏中固有巨噬细胞和浸润单核细胞的相对较新区分是一个重要的进展，将增强我们对不同髓样细胞群体的各种作用的理解，但需要特定的工具来严格定义每个细胞对损伤、修复和向慢性疾病转变的贡献。
肾脏中的固有巨噬细胞在发育和稳态过程中形成了具有各种支持作用的网络。虽然这些细胞的分类在文献中经常被混淆，但它们在损伤和修复过程中的作用的证据正在逐渐积累。目前的迹象表明，它们在损伤过程中可能作用不大，但在恢复阶段可能很重要。然而，它们的参与也可能依赖于它们对环境线索的激活状态。对髓样细胞 M1/M2 表型的研究揭示了一些有助于损伤和/或恢复表现的表型，但仍难以得出详细结论。在这里，我们将讨论固有细胞在这些过程中的潜在作用，以及 M1/M2 系统在IRI 后用于定义髓样细胞反应的情况。
需要对固有细胞与募集的髓样细胞对肾脏损伤、恢复和慢性疾病的贡献进行额外的特异性分析。此外，超越简单的 M1/M2 分类的髓样细胞激活状态的贡献是一个需要密切关注的重要领域。我们评估固有细胞的能力在不断提高，对 M1/M2 系统的局限性的认识也在不断提高。这些都是有希望的发展，为肾脏损伤和疾病研究的未来奠定了良好的基础。
