A VgrG2b fragment cleaved by caspase-11/4 promotes Pseudomonas aeruginosa infection through suppressing the NLRP3 inflammasome

Abstract

The T6SS of Pseudomonas aeruginosa plays an essential role in the establishment of chronic infections. Inflammatory cytokines mediated by inflammasomes are crucial for the body to resist bacterial infections. Here we found that during the infection of P. aeruginosa, non-canonical inflammasome was activated in macrophages, but the activation of downstream NLRP3 inflammasome was inhibited. The VgrG2b of P. aeruginosa is recognized and cleaved by caspase-11, generating a free C-terminal fragment. The VgrG2b C-terminus can bind to NLRP3, inhibiting the activation of the NLRP3 inflammasome by rejecting NEK7 binding to NLRP3. Administrating a specific peptide that inhibits the cleavage of VgrG2b by caspase-11 to mice can significantly improve their survival rate during infection. Our discovery elucidates a mechanism by which P. aeruginosa inhibits host immune response, providing a new approach for the future clinical treatment of P. aeruginosa infections.