TLR4 and infection: Increased caspase-1 cleavage and IL-1β secretionoccurred in IKKβ-deficient macrophages infected with Y.pestis expressing YopJCO92, confirming that theNF-κB pathway can negatively regulate inflammasome activation.K+ efflux, NLRP3 and ASC were important for secretion ofIL-1β in response to Y. pestis KIM infection as shown usingmacrophages lacking inflammasome components or by the addition of exogenous KCl.These data show that caspase-1 is activated in naïve macrophages inresponse to infection with a pathogen that inhibits IKKβ and MAPK kinasesand induces TLR4-dependent apoptosis.