Cloning of porcine triggering receptor expressed on myeloid cells-1 (TREM-1) and its induction by lipopolysaccharide, peptidoglycan, and Salmonella enterica serovar Typhimurium infection.

Triggering receptors expressed on myeloid cells (TREM) are a family of activating receptors expressed on neutrophils and monocytes. These receptors are involved in regulation of immunity by inducing the expression of inflammatory cytokines and adhesion molecules, augmenting dendritic cell maturation, and are implicated in septic shock. Here we report the cloning of full-length TREM cDNA from porcine bone marrow cells, which predicts a 238 amino-acid peptide. Treating porcine bone marrow cells with lipopolysaccharide or peptidoglycan caused an increase in TREM-1 expression. Moreover, bone marrow cells derived from pigs that were orally challenged with Salmonella enterica serovar Typhimurium showed increases in TREM-1 at 8 and 24 h post-infection, respectively. Complete down-regulation of TREM-1 expression was observed at 48 h post-infection. These findings provide fundamental comparative data indicating that bacterial infection induces TREM-1 expression.