First Department of Internal Medicine, University of Toyama, Toyama, Japan.
Department of Metabolism and Nutrition, University of Toyama, Toyama, Japan.
J Diabetes Investig. 2019 Nov;10(6):1394-1400. doi: 10.1111/jdi.13114. Epub 2019 Aug 5.
Adipose tissue (AT) is composed not only of adipocytes, but also of macrophages, endothelial cells and preadipocytes. Macrophages are an important component of AT, and are involved in tissue homeostasis, tissue repair and fibrosis. AT-resident macrophages are categorized into two subtypes, the M1-like and M2-like macrophages. M2-like macrophages are reported to play anti-inflammatory roles, and to be involved in clearing and removal of dying/dead adipocytes, and recruiting adipocyte progenitors (APs). M2-like macrophages are also reported to be involved in the promotion of fibrosis in a transforming growth factor-β-dependent manner. However, the precise roles of M2-like macrophages in the AT have not yet been clearly delineated. Recently, we generated genetically engineered transgenic mice in which CD206 M2-like macrophages can be conditionally depleted. Unexpectedly, we found that the depletion of CD206 M2-like macrophages resulted in the enhanced generation of smaller adipocytes, improved insulin sensitivity and proliferation of APs. We further clarified that the CD206 M2-like macrophages directly interact with the APs to regulate their growth/differentiation and adipogenesis, thereby controlling adiposity and systemic insulin sensitivity. In the present review, we discuss how CD206 M2-like macrophages provide a niche for APs and maintain glucose homeostasis.
脂肪组织(AT)不仅由脂肪细胞组成,还包括巨噬细胞、内皮细胞和前体脂肪细胞。巨噬细胞是 AT 的重要组成部分,参与组织稳态、组织修复和纤维化。AT 驻留巨噬细胞分为两种亚型,M1 样和 M2 样巨噬细胞。据报道,M2 样巨噬细胞发挥抗炎作用,并参与清除和去除死亡/凋亡的脂肪细胞,以及招募脂肪细胞前体(APs)。M2 样巨噬细胞还被报道通过转化生长因子-β(TGF-β)依赖性方式参与纤维化的促进。然而,M2 样巨噬细胞在 AT 中的确切作用尚未明确。最近,我们生成了基因工程转基因小鼠,其中 CD206 M2 样巨噬细胞可以条件性耗竭。出乎意料的是,我们发现 CD206 M2 样巨噬细胞的耗竭导致更小的脂肪细胞生成增加、胰岛素敏感性提高和 APs 增殖。我们进一步阐明 CD206 M2 样巨噬细胞直接与 APs 相互作用,调节它们的生长/分化和脂肪生成,从而控制肥胖和全身胰岛素敏感性。在本综述中,我们讨论了 CD206 M2 样巨噬细胞如何为 APs 提供栖息地并维持葡萄糖稳态。