Bone cells and immune cells share the same microenvironments in the bone marrow, communicating through various cytokines. Osteoblasts, osteoclasts and osteocytes are not only degrading or forming bone but have distinct roles in the immune regulation . Thus, much attention has been paid to the interdisciplinary filed, osteoimmunology, studying the interaction and shared molecules between bone and immune systems ( Nat Rev Rheumatol 5, 667-76, 2009 ) . Here I summarize the recent advance in osteoimmunology and its relevance in the studies on autoimmune diseases such as rheumatoid arthritis.
Self-tolerance is primarily established by positive selection followed by negative selection of self-reactive T cells in the thymus. We found that the transcription factor Fezf2 plays a critical role in central tolerance by directly regulating tissue-restricted antigen expression in mTECs independently of Aire (Cell 163, 975-87, 2015). We also reported that the human variations of thymoproteasome subunit b 5t impact CD8 T cell selection , indicating that genetic variations in antigen-peptide processing machinery influence T cell repertoire selection and susceptibility to autoimmune disease ( Science Immunology 02 Jun 2017: 2, eaan5165) .