Soluble triggering receptor expressed on myeloid cells 2 (sTREM2) positively regulates lipopolysaccharide-induced expression of CXC chemokine ligand 10 and 11 in mouse macrophages

TREM2 (Triggering receptor expressed on myeloid cells 2) is the causative gene for Nasu-Hakola disease, which is characterized by multiple bone cysts and leukoencephalopathy. In addition, mutations in this gene have been found to be correlated with the onset of Alzheimer's disease. TREM2 is an immunoreceptor expressed on dendritic cells, microglia, osteoclasts, and macrophages. TREM2 on the cell membrane is shed by some proteases and released as soluble TREM2 (sTREM2). Meanwhile, several TREM2 ligands have been reported, and lipopolysaccharide (LPS) is one of the candidates. Using RNA interference to examine TREM2-mediated LPS response in macrophages, we identified five chemokines whose expression was induced via TREM2. Furthermore, we showed that LPS-induced expression of CXC-motif chemokine ligand (Cxcl10) and Cxcl11 among the five chemokines was mediated in part through sTREM2. These results suggest that sTREM2 has cytokine-like functions in macrophages.