Immunopharmacological Targeting of Immune-Bone Crosstalk in Bone Disorders: Mechanisms and Therapeutic Perspectives

Bone remodeling is a tightly regulated physiological process governed by the coordinated activities of bone-forming osteoblasts and bone-resorbing osteoclasts. Emerging evidence highlights the immune system as a critical regulator of this process through complex cellular interactions and signaling networks, giving rise to the concept of osteoimmunology. Immune cells, including T cells, B cells, and macrophages, modulate bone homeostasis by secreting cytokines and engaging in direct cell-cell communication that influences osteoclast differentiation and osteoblast function. Key molecular pathways implicated in immune-mediated bone remodeling include the RANK-RANKL-OPG axis, Wnt/β-catenin signaling, and pro-inflammatory cytokine networks involving TNF-α, IL-6, and IL-17. Dysregulation of these pathways contributes to the pathogenesis of bone disorders such as osteoporosis, rheumatoid arthritis, and other inflammatory bone diseases. From a pharmaceutical perspective, targeting immune-bone signaling pathways has emerged as a promising therapeutic strategy. Approved biologics, including monoclonal antibodies against RANKL and inflammatory cytokines, have demonstrated clinical efficacy in reducing pathological bone resorption. In addition, emerging immunopharmacological approaches such as modulation of regulatory T cells, immune checkpoint signaling, and cytokine-driven intracellular pathways offer novel opportunities for drug development. Advances in precision medicine and immunotherapy further support the development of personalized interventions for immune-mediated bone disorders. This review critically examines immune-bone crosstalk with an emphasis on pharmacologically actionable targets and emerging therapeutic strategies, providing insights into future directions for restoring skeletal homeostasis and preventing immune-driven bone loss.