Gross, C. J. | bioRxiv Science

bioRxiv2025

NEK7 accelerates NLRP3 inflammasome activation

The NLRP3 inflammasome is a major driver of immunopathology, making it a sought-after drug target. In spite of two decades of intense research, its precise activation mechanism remains elusive, impeding inhibitor design. NEK7 was reported as essential for NLRP3 activation, and several newly identified inhibitors were suggested to act by interfering with their interaction. Here we report that NEK7 accelerates, but is in principle dispensable for NLRP3 activation. The onset of inflammasome activation was unaltered in the absence of NEK7, yet the rate of cells to undergo inflammasome formation and subsequent pyroptosis was approximately 4-fold reduced. Therefore, therapeutic targeting of the NEK7-NLRP3 interaction might have an incomplete effect, which should be considered for drug development. We confirmed entrectinib as a NEK7-dependent inhibitor, while other published compounds turned out not to rely on it. Our results support two possible scenarios for the role of NEK7 in NLRP3 activation: either, NEK7 accelerates one unique pathway of NLRP3 activation, or it is essential for a fast pathway, while being dispensable for a second, slower mode of NLRP3 activation.

immunology↗

bioRxiv2022

Tyrosine kinase inhibitors trigger lysosomal damage-associated cell lysis to activate the NLRP3 inflammasome

Inflammasomes are intracellular protein complexes that control proteolytic maturation and secretion of inflammatory interleukin-1 (IL-1) family cytokines and are thus important in host defense. While some inflammasomes are activated simply by binding to pathogen-derived molecules, others, including those nucleated by NLRP3 and NLRP1, have more complex activation mechanisms that are not fully understood. We screened a library of small molecules to identify new inflammasome activators that might shed light on activation mechanisms. In addition to validating dipeptidyl peptidase (DPP) inhibitors as NLRP1 activators, we find that clinical tyrosine kinase inhibitors (TKIs) including imatinib and masitinib activate the NLRP3 inflammasome. Mechanistically, these TKIs cause lysosomal swelling and damage, leading to cathepsin-mediated destabilization of myeloid cell membranes and cell lysis. This is accompanied by potassium (K+) efflux, which activates NLRP3. Both lytic cell death and NLRP3 activation but not lysosomal damage induced by TKIs are prevented by the cytoprotectant high molecular weight polyethylene glycol (PEG). Our study establishes a screening method that can be expanded for inflammasome research and immunostimulatory drug development, and provides new insight into immunological off-targets that may contribute to efficacy or adverse effects of TKIs. One Sentence SummaryA functional small molecule screen identifies imatinib, masitinib and other tyrosine kinase inhibitors that destabilize myeloid cell lysosomes, leading to cell lysis and K+ efflux-dependent NLRP3 inflammasome activation.

immunology↗