Periosteal CD68+ F4/80+ Macrophages Are Mechanosensitive for Cortical Bone Formation by Secretion and Activation of TGF-β1.

Mechanical force regulates bone density, modeling, and homeostasis. Substantial periosteal bone formation is generated by external mechanical stimuli, yet its mechanism is poorly understood. Here, it is shown that myeloid-lineage cells differentiate into subgroups and regulate periosteal bone formation in response to mechanical loading. Mechanical loading on tibiae significantly increases the number of periosteal myeloid-lineage cells and the levels of active transforming growth factor β (TGF-β), resulting in cortical bone formation. Knockout of Tgfb1 in myeloid-lineage cells attenuates mechanical loading-induced periosteal bone formation in mice. Moreover, CD68+ F4/80+ macrophages, a subtype of myeloid-lineage cells, express and activate TGF-β1 for recruitment of osteoprogenitors. Particularly, mechanical loading induces the differentiation of periosteal CD68+ F4/80- myeloid-lineage cells to the CD68+ F4/80+ macrophages via signaling of piezo-type mechanosensitive ion channel component 1 (Piezo1) for TGF-β1 secretion. Importantly, CD68+ F4/80+ macrophages activate TGF-β1 by expression and secretion of thrombospondin-1 (Thbs1). Administration of Thbs1 inhibitor significantly impairs loading-induced TGF-β activation and recruitment of osteoprogenitors in the periosteum. The results suggest that periosteal myeloid-lineage cells respond to mechanical forces and consequently produce and activate TGF-β1 for periosteal bone formation. © 2021 The Authors. Advanced Science published by Wiley-VCH GmbH.

Citation

Ruoxian Deng, Changwei Li, Xiao Wang, Leilei Chang, Shuangfei Ni, Weixin Zhang, Peng Xue, Dayu Pan, Mei Wan, Lianfu Deng, Xu Cao. Periosteal CD68+ F4/80+ Macrophages Are Mechanosensitive for Cortical Bone Formation by Secretion and Activation of TGF-β1. Advanced science (Weinheim, Baden-Wurttemberg, Germany). 2022 Jan;9(3):e2103343

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PMID: 34854257

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