The biology of TREM receptors

Triggering receptors expressed on myeloid cells (TREMs) encompass a family of cell-surface receptors chiefly expressed by granulocytes, monocytes and tissue macrophages. These receptors have been implicated in inflammation, neurodegenerative diseases, bone remodelling, metabolic syndrome, atherosclerosis and cancer. Here, I review the structure, ligands, signalling modes and functions of TREMs in humans and mice and discuss the challenges that remain in understanding TREM biology. In this Review, Marco Colonna provides a comprehensive summary of the triggering receptor expressed on myeloid cells (TREM) family of receptors. TREMs are important for modulating signalling in myeloid cells and have now been implicated in many different disease settings, including inflammatory diseases, autoimmunity, neurodegeneration and cancer.