NLRP3 and Salmonella Infections: Strikingly, Salmonella infection or nigericin stimulation of the NLRP3 inflammasome in COX2 (Ptgs2)-deficient macrophages had no effect on the release of IL-1β, IL-18, IL-6, inflammasome oligomerization or caspase-1 activation (S2B–S2F Fig).