IL-1ß-driven neutrophilia preserves antibacterial defense in the absence of the kinase IKKß.

ABSTRACT

Transcription factor NF-κB and its activating kinase IKKß are associated with inflammation and are believed to be critical for innate immunity. Despite the likelihood of immune suppression, pharmacological blockade of IKKß-NF-κB has been considered as a therapeutic strategy. However, we found neutrophilia in mice with inducible deletion of IKKß (Ikkß(Δ) mice). These mice had hyperproliferative granulocyte-macrophage progenitors and pregranulocytes and a prolonged lifespan of mature neutrophils that correlated with the induction of genes encoding prosurvival molecules. Deletion of interleukin 1 receptor 1 (IL-1R1) in Ikkß(Δ) mice normalized blood cellularity and prevented neutrophil-driven inflammation. However, Ikkß(Δ)Il1r1(-/-) mice, unlike Ikkß(Δ) mice, were highly susceptible to bacterial infection, which indicated that signaling via IKKß-NF-κB or IL-1R1 can maintain antimicrobial defenses in each other's absence, whereas inactivation of both pathways severely compromises innate immunity.