Osteoimmune Interactions in Inflammatory Bowel Disease: Central Role of Bone Marrow Th17 TNFα Cells in Osteoclastogenesis

Osteoimmunology is an interdisciplinary research field dedicated to the study of the crosstalk between the immune and bone systems. CD4(+) T cells are central players in this crosstalk. There is an emerging understanding that CD4(+) T cells play an important role in the bone marrow (BM) under physiological and pathological conditions and modulate the differentiation of bone-resorbing osteoclasts. However, identification of the mechanisms that maintain CD4(+) T cells in the BM is still a matter of investigation. This article describes the CD4(+) T cell populations of the BM and reviews their role as osteoclastogenic population in inflammatory bowel disease.