Sphingosine 1-phosphate and osteoporosis: pathophysiology and therapeutic aspects—a narrative review

Sphingosine 1-phosphate (S1P) regulates many cellular functions, such as differentiation, proliferation, migration, morphogenesis, cytoskeletal organization, adhesion, tight junction assembly, apoptosis and the localization of different cell types. S1P also controls the migration of osteoclast precursors between the blood and bone, and it keeps osteoclast precursors away from bone surfaces to reduce bone degradation, thus preventing bone decay. Osteoporosis is a systemic bone disease that predisposes patients to bone fracture due to decreased bone density and quality, disrupted bone microarchitecture, and increased bone fragility. As the global elderly population increases, the incidence of osteoporosis will greatly increase, and the associated adverse consequences will become more serious. S1P plays an important role in homeostasis, and disruption of the balance between osteoblasts and osteoclasts may induce osteoporosis. A high frequency of osteoporotic fracture is associated with increased plasma S1P levels. Studies have shown that S1P is an important therapeutic target in osteoporosis because it controls the migration of osteoclast precursors, vigorously maintains the bone mineralization process, and is a critical regulator of osteoclastogenesis. Improved understanding of the functional roles and molecular mechanisms of S1P in bone turnover could facilitate the discovery of novel targets for the treatment of osteoporosis. This review provides a critical discussion of the role of S1P in osteoporosis and treatments.