The Role of Osteoclasts in Psoriatic Arthritis

Psoriatic arthritis (PsA) is a chronic immune-mediated inflammatory disease related to psoriasis involving bone and cartilage. It is a heterogeneous disorder with a variety of clinical manifestations, which can include peripheral arthritis, axial spondylitis, enthesitis, skin and nail disease, dactylitis, uveitis, osteitis, inflammatory bowel disease. The distinctive feature of PsA is enthesitis. The characteristic bone erosion at the bone-pannus junction in PsA is mediated by osteoclasts, which are multinucleated giant cells derived from hematopoietic stem cells. Although the pathological mechanism of osteoclasts in PsA is mainly related to the destruction of the diseased joint, the exact pathogenesis of PsA is complex and the factors involved in initiation and termination of osteoclast need to be further explored. Much attention has been paid to the importance of osteoclast in psoriasis arthritis for decades. Based on the role of osteoclasts in PsA, our review discusses the formation and characteristics of multinucleated osteoclasts in PsA, summarizes current developments in osteoclast-related pathways in PsA including classical receptor activator of nuclear factor-κB-receptor activator of nuclear factor-κB ligand-osteoprotegerin pathway and immunomodulatory factors, as well as their advances and corresponding treatment. At present, the molecular and signal pathway that interacts with osteoclasts in the pathogenesis of PSA has not been fully elucidated, therefore more detailed studies are expected in the near future.