Bone resorption

Abstract

<jats:title>Abstract</jats:title><jats:p>Bone is continually being removed and replaced throughout life by the actions of osteoblasts (bone forming cells) and osteoclasts (bone resorbing cells). Bone loss in disease can be caused by either excessive bone resorption or decreased bone formation, or both. Recently, significant advances have been made in our understanding of the factors that regulate the formation and activation of the cell type in bone responsible for bone resorption, the osteoclast. Bone loss pathologies can be broadly divided into two types: systemic diseases, such as osteoporosis, in which bone is lost throughout the skeleton, and conditions characterized by more focal bone loss, such as the joint erosions in rheumatoid arthritis, tumor‐induced osteolysis, periodontal bone loss, and bone loss around orthopedic prostheses. Although the same molecules appear to be involved in bone resorption in health and disease, they appear to be expressed by different cell types, depending on the particular pathology concerned. This review of bone resorption discusses the current understanding of osteoclast formation and activity and the factors that are responsible for bone loss in various pathologies, with particular emphasis on bone loss in inflammatory conditions.</jats:p>