Mono Sodium Urate Crystal-induced Peritonitis for in vivo Assessment of Inflammasome Activation

Due to its particulate material, mono-sodium urate (MSU) crystals are potent activators of the NOD-like receptor NLRP3. Upon activation, NLRP3 induces the formation of inflammasome complexes, which lead to the production and release of mature IL-1β. Bioactive IL-1β is a potent activator of innate immune responses and promotes recruitment of inflammatory cells, including neutrophils from the blood into damaged/inflamed tissues. This protocol describes a method to study in vivo inflammasome activation via intraperitoneal injection of MSU crystals. MSU-injection results in a drastic increase of intraperitoneal IL-1β levels, promoting neutrophil infiltration. Early-stage neutrophil numbers correlate with the amount of released IL-1β and can be used as a read-out for the extent of in vivo inflammasome activation. In addition, this protocol might also be used as a sterile peritonitis model, to investigate mechanisms of neutrophil recruitment to the peritoneum, or as a means to obtain large numbers of in vivo activated neutrophils.