Caspase-11 Plays a Protective Role in Pulmonary Acinetobacter baumannii Infection

Activation of caspase-11 by some Gram-negative bacteria triggers the caspase-1/interleukin 1 beta (IL-1 beta) pathway, independent of canonical inflammasomes. Acinetobacter baumannii is a Gram-negative, conditionally pathogenic bacterium that can cause severe pulmonary infection in hospitalized patients. A. baumannii was revealed to activate canonical and noncanonical inflammasome pathways in bone marrow-derived macrophages (BMDMs). Pulmonary infection of caspase-11(-/-) mice with A. baumannii showed that caspase-11 deficiency impaired A. baumannii clearance, exacerbated pulmonary pathological changes, and enhanced susceptibility to A. baumannii. These data indicate that the caspase-11-mediated innate immune response plays a crucial role in defending against A. baumannii.