Prdx4 limits caspase-1 activation and restricts inflammasome-mediated signaling by extracellular vesicles.

Simone Lipinski, Steffen Pfeuffer, Philipp Arnold, Christian Treitz, Konrad Aden, Henriette Ebsen, Maren Falk-Paulsen, Nicolas Gisch, Antonella Fazio, Jan Kuiper, Anne Luzius, Susanne Billmann-Born, Stefan Schreiber, Gabriel Nuñez, Hans-Dietmar Beer, Till Strowig, Mohamed Lamkanfi, Andreas Tholey, Philip Rosenstiel
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The EMBO journal
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Inflammasomes are cytosolic protein complexes, which orchestrate the maturation of active IL-1β by proteolytic cleavage via caspase-1. Although many principles of inflammasome activation have been described, mechanisms that limit inflammasome-dependent immune responses remain poorly defined. Here, we show that the thiol-specific peroxidase peroxiredoxin-4 (Prdx4) directly regulates IL-1β generation by interfering with caspase-1 activity. We demonstrate that caspase-1 and Prdx4 form a redox-sensitive regulatory complex via caspase-1 cysteine 397 that leads to caspase-1 sequestration and inactivation. Mice lacking Prdx4 show an increased susceptibility to LPS-induced septic shock. This effect was phenocopied in mice carrying a conditional deletion of Prdx4 in the myeloid lineage (Prdx4-ΔLysMCre). Strikingly, we demonstrate that Prdx4 co-localizes with inflammasome components in extracellular vesicles (EVs) from inflammasome-activated macrophages. Purified EVs are able to transmit a robust IL-1β-dependent inflammatory response in vitro and also in recipient mice in vivo. Loss of Prdx4 boosts the pro-inflammatory potential of EVs. These findings identify Prdx4 as a critical regulator of inflammasome activity and provide new insights into remote cell-to-cell communication function of inflammasomes via macrophage-derived EVs.