Heme Oxygenase-1 in Bone Remodeling: Molecular Mechanisms and Therapeutic Implications.

Bone remodeling is a dynamic and tightly regulated process that maintains skeletal homeostasis through a balance between bone formation by osteoblasts and bone resorption by osteoclasts. Disruption of this balance contributes to the development of bone-related disorders, particularly osteopenia, osteoporosis and osteogenesis imperfecta, which weaken, deform, or cause fractures. Increasing evidence indicates that oxidative stress and chronic inflammation impair osteoblast functions while promoting osteoclast differentiation and activity. Heme oxygenase-1 (HO-1) is a stress-inducible enzyme with cytoprotective, antioxidant, and anti-inflammatory properties. Besides its primary role in cellular defense against oxidative stress and inflammatory damage, HO-1 has been shown to be involved in both osteoblast differentiation and osteoclastogenesis. Through its interaction with key regulatory systems, including the receptor activator of nuclear factor κB (RANK)-receptor activator of nuclear factor κB ligand (RANKL)-osteoprotegerin axis and redox-sensitive signaling pathways, HO-1 contributes to maintenance of optimal bone remodeling. The enzyme also plays a role in modulating metabolic processes in the bone. This review highlights the role of HO-1 in bone formation, bone resorption, and related pathophysiologic conditions. Furthermore, the therapeutic potential of HO-1 as a target for bone disorders is discussed.