The Crosstalk Between B Cells and the Skeletal System During Development, Aging, and in Pathological Conditions

In this review, we describe the interaction between B cells and bone during development, aging, and disease.  RECENT FINDINGS: There is an increased interest in identifying the mechanisms of interaction between immune cells and the skeletal system. This knowledge is critical for understanding the pathology of autoimmune diseases and developing therapeutic interventions. Humoral immunity depends on B cells and their secreted immunoglobulin (antibodies). Earlier studies described B cell influence on the skeletal system, with a major focus on the role of plasma cells and secreted antibodies. The contribution of bone marrow developing B cells to the skeletal system was still poorly studied and represents a gap in our knowledge. This is an active area of investigation in our research group. The crosstalk between B cells and bone starts as early as the commitment of hematopoietic stem cells to the B cell lineage and the differentiation of mesenchymal stem cells to osteoblast progenitors. This crosstalk is active during different developmental stages and continues throughout the life of the individual, especially since both B cells and bone cells share the same developmental niche. Bi-directional interaction of developing B cells and osteoblasts, osteoclasts, and chondroblasts ensures their normal development and functional activity. During aging, this interaction is disrupted, leading to disease progression, decreased bone mass, and osteoporosis. A better understanding of B cell-bone interactions will help identify novel immune targets that might provide therapeutic benefit for the elderly and patients.