Recent advances in inflammatory markers.-HMGB1 and TREM-1-

Abstract

This review describes recent advances in studies of the inflammatory markers, high mobility group box 1 (HMGB1) and triggering receptor expressed on myeloid cells-1 (TREM-1). HMGB1 is a ubiquitous nuclear protein that is widely distributed among mammalian cells, passively released from necrotic cells and actively released from stimulated inflammatory cells. Released HMGB1 can bind to RAGE and/or TLRs and elicit inflammatory responses through the production of pro-inflammatory cytokines and chemokines. Extracellular levels of HMGB1 are increased in patients with various diseases including sepsis, cancer, ARDS, DIC, RA, acute coronary syndrome, heart failure and atherosclerosis. Thus, HMGB1 might function as an endogenous immune adjuvant and play a crucial role in the development of various inflammatory diseases. TREM-1 is a cell surface receptor expressed on phagocytes that can amplify inflammatory responses initiated by TLRs. Although a natural ligand for TREM-1 has not been identified, agonistic antibodies against TREM-1 can promote synergistic enhancement of TLR-medicated inflammatory responses. Furthermore, the expression of TREM-1 and soluble TREM-1 is increased in sepsis. These finding indicate that HMGB1 and TREM-1 might be useful inflammatory markers for the diagnosis and monitoring of various inflammatory diseases.