Peptidoglycan recognition proteins-maintaining immune homeostasis and normal development

Peptidoglycan recognition proteins (PGRPs) are innate immune molecules with a diverse array of functions. In this issue of Cell Host & Microbe, Maillet and colleagues demonstrate that a Drosophila PGRP, PGRP-LF, functions as a negative regulator of the Drosophila immune deficiency (IMD) pathway, an innate immune signaling mechanism responsive to Gram-negative bacteria. PGRP-LF deficiency results in unregulated immune signaling, causing excessive antimicrobial peptide synthesis and, surprisingly, developmental defects.