Osteoimmunology: the little niche with the big impact.

Abstract

Osteoimmunology, which emerged in the early 2000s, was paradigm-shifting in its integration of immunology and skeletal research, recognizing the pivotal role of immunoreceptors on preosteoclasts, immune cells, and proinflammatory cytokines contributing to inflammatory bone remodeling. Numerous immunoreceptors and key signaling pathways were defined that regulate osteoclastogenesis. A dynamic interplay between lymphocytes and osteoclasts was found to be fundamental to maintaining bone homeostasis and contributing to pathological bone resorption in inflammatory arthritis or malignant metastasis. Osteoimmunology has expanded to include crosstalk between osteoclasts and osteoblasts, the role of bone marrow stromal cells in maintaining the hematopoietic stem cell niche, and the influence of the microbiome on lymphocytes that drive bone remodeling. Deciphering the intricate mechanisms that govern the immune system's regulation of bone remodeling remains a central objective in osteoimmunology, offering promising avenues for the development of targeted therapeutic strategies aimed at restoring skeletal equilibrium.