The NLRP3 inflammasome affects DNA damage responses after oxidative and genotoxic stress in dendritic cells

Abstract

The NOD-like receptor (NLR) family pyrin domain-containing 3 (NLRP3) inflammasome is a cytoplasmic protein complex that mediates inflammatory responses to a broad array of danger signals. The inflammasome drives caspase-1 activation and promotes secretion of the pro-inflammatory cytokines IL-1β and IL-18, and might also participate in other cellular processes. Here, we tried to identify new pathways regulated by the NLRP3 inflammasome in murine dendritic cells (DCs) in response to monosodium urate (MSU) crystals. Using a transcriptomic approach, we found that DCs from Nlrp3(-/-) mice responded to MSU with differential expression of genes involved in the DNA damage response and apoptosis. Upon exposure to MSU or other ROS-mobilizing stimuli (rotenone and γ-radiation), DNA fragmentation was markedly ameliorated in Nlrp3(-/-) and casp-1(-/-) DCs compared with WT DCs. Moreover, Nlrp3(-/-) DCs experienced significantly less oxidative DNA damage mediated by ROS. A significant decrease of the expression of several genes involved in double-strand and base-excision DNA repair was observed in WT DCs. Basal DNA repair capacity in WT DCs resulted in activation and stabilization of p53 in vitro and in vivo, which resulted in increased cell death compared with that in Nlrp3(-/-) DCs. These data provide the first evidence for the involvement of the NLRP3 inflammasome in DNA damage responses induced by cellular stress.

Keywords: Apoptosis; DNA damage response; Innate immunity; NLRP3 inflammasome.