Muramyl dipeptide

Muramyl dipeptide is constituent of both Gram-positive and Gram-negative bacteria composed of N-acetylmuramic acid linked by its lactic acid moiety to the N-terminus of an -alanine -isoglutamine dipeptide.
It can be recognized by the immune system as a pathogen-associated molecular pattern and activate the NALP3 inflammasome which in turn leads to cytokine activation, especially IL-1α and IL-1β.