Two macrophages, osteoclasts and microglia:from development to pleiotropy

• 作者: Ji-Won Lee In-Hee Lee Tadahiro Iimura Sek Won Kong
• 来源期刊: 骨研究（英文版）
• 年，卷（期）: 2021,（2）
• 所属期刊栏目: REVIEWS
• 页码范围: 143-152
• 页数: 10页
• 语种: 英文

摘要

INTRODUCTION Bone undergoes constant remodeling to maintain bone home-ostasis between bone formation and resorption by osteoblasts and osteoclasts, respectively.1 Bone remodeling is a process of bone resorption followed by replacement of new bone formation, which is a tightly balanced work referred to as coupling.2 The osteoclast is a large multinucleated cell derived from monocyte/macrophage lineage of pluripotential hematopoietic stem cells (HSCs). Osteo-clasts degrade the bone matrix with hydrogen ions and catalytic enzymes, whereas osteoblasts—mononuclear cells derived from mesenchymal cells—secrete organic matrix molecules that con-tribute to the formation of new bone. Osteoclasts undergo differentiation and fusion resulting in multinucleated cells, in the presence of macrophage colony-stimulating factor (M-CSF, also known as CSF1) and the key osteoclastogenic cytokine, receptor activator of NF-kB ligand (RANKL), characterized by expression of osteoclast markers, such as tartrate-resistant acid phosphatase,3 matrix metalloproteinase (MMP-9),4 cathepsin K5, and vacuolar [H+]-ATPase.6 Bone resorption is a necessary process for bone growth, tooth eruption, fracture healing and maintaining appro-priate level of calcium in blood. Under pathological conditions such as estrogen deficiency or inflammatory conditions like rheumatoid arthritis, abnormal osteoclast proliferation, and differ-entiation accelerate bone resorption that results in osteolysis.