N-Terminal Peptide of PGLYRP1/Tag7 Is a Novel Ligand for TREM-1 Receptor

An investigation of innate immunity receptors sheds light on the mechanisms of inflammation and associated immune reactions. One of the key immune regulators is the TREM-1 receptor, which is involved in both inflammation and antitumor immune response. In this article, we have obtained a new ligand for the TREM-1 receptor. The peptide, named N3, is a part of the innate immune protein PGLYRP1/Tag7. It is responsible for activating the TREM-1 signaling pathway. Here, we have demonstrated that the N3 peptide acts like other TREM-1 receptor ligands: its binding results in a mild inflammation response and appearance of cytotoxic lymphocytes. We have shown that cytotoxic populations of lymphocytes in N3 peptide-treated PBMCs are similar to those treated with Tag7 or Hsp70. We also determined the part of the N3 peptide responsible for binding to TREM-1. The resulting peptide (N9) consists of nine amino acids and can be considered as a potential peptide that blocks TREM-1 signaling.