Pro-inflammatory caspase-1 is a key player in innate immunity. Caspase-1 processes interleukin (IL)-1β and IL-18 to their mature forms and triggers pyroptosis. These caspase-1 functions are linked to its enzymatic activity. However, loss-of-function missense mutations in CASP1 do not prevent autoinflammation in patients, despite decreased IL-1β production. In vitro data suggest that enzymatically inactive caspase-1 drives inflammation via enhanced nuclear factor κB (NF-κB) activation, independent of IL-1β processing. Here, we report two mouse models of enzymatically inactive caspase-1-C284A, demonstrating the relevance of this pathway in vivo. In contrast to Casp1-/- mice, caspase-1-C284A mice show pronounced hypothermia and increased levels of the pro-inflammatory cytokines tumor necrosis factor alpha (TNF-α) and IL-6 when challenged with lipopolysaccharide (LPS). Caspase-1-C284A signaling is RIP2 dependent and mediated by TNF-α but independent of the NLRP3 inflammasome. LPS-stimulated whole blood from patients carrying loss-of-function missense mutations in CASP1 secretes higher amounts of TNF-α. Taken together, these results reveal non-canonical caspase-1 signaling in vivo.

Original publication

DOI

10.1016/j.celrep.2020.01.090

Type

Journal article

Journal

Cell Rep

Publication Date

25/02/2020

Volume

30

Pages

2501 - 2511.e5

Keywords

NF-κB, Rip2, TNF-α, caspase-1, enzymatic activity, non-canonical caspase-1 signaling, Adolescent, Adult, Animals, Caspase 1, Child, Child, Preschool, Genetic Loci, Genotype, HEK293 Cells, Heterozygote, Humans, Inflammation, Mice, Inbred C57BL, Mutation, Receptor-Interacting Protein Serine-Threonine Kinase 2, Signal Transduction, Tumor Necrosis Factor-alpha, Young Adult