PGLYRP1 and gram-negative bacterial infections: For example, upon systemic Gram-negative bacterial infection via septic injury, the immune deficiency (IMD) pathway is activated [2–6], which involves binding of diaminopimelic acid (DAP)-type peptidoglycan (PGN) present in Gram-negative bacteria by the trans-membrane peptidoglycan-recognition protein (PGRP-LCx) and oligimerization of PGRP-LCx.