Cutting Edge: Inflammatory Responses Can Be Triggered by TREM-1, a Novel Receptor Expressed on Neutrophils and Monocytes

TLDR

TREM‑1 is a myeloid receptor expressed on neutrophils and a subset of monocytes, whose expression rises in response to bacterial LPS. Engagement of TREM‑1 activates neutrophils and monocytes by triggering cytokine release, degranulation, Ca²⁺ mobilization, ERK1/2 and PLC‑γ phosphorylation, and requires the adapter DAP12. TREM‑1 drives neutrophil and monocyte activation and likely plays a key role in inflammatory responses.

Abstract

Abstract We have identified new activating receptors of the Ig superfamily expressed on human myeloid cells, called TREM (triggering receptor expressed on myeloid cells). TREM-1 is selectively expressed on blood neutrophils and a subset of monocytes and is up-regulated by bacterial LPS. Engagement of TREM-1 triggers secretion of IL-8, monocyte chemotactic protein-1, and TNF-α and induces neutrophil degranulation. Intracellularly, TREM-1 induces Ca2+ mobilization and tyrosine phosphorylation of extracellular signal-related kinase 1 (ERK1), ERK2 and phospholipase C-γ. To mediate activation, TREM-1 associates with the transmembrane adapter molecule DAP12. Thus, TREM-1 mediates activation of neutrophil and monocytes, and may have a predominant role in inflammatory responses.