Abstract
Injury or stress can induce intracellular translocation and release of nuclear HMGB1, a DAMP molecule known to participate in inflammation and other pathological processes. Active release of HMGB1 from stimulated macrophages can be mediated by inflammasomes, which cleave Gasdermin D to form pores on cytoplasmic membranes. We previously had shown that active release of HMGB1 from autophagy deficient hepatocytes also depended on the inflammasome but how the inflammasome was activated was not known. Here we report that persistent activation of transcription factor NRF2 under the autophagy deficient condition led to transcriptional upregulation of Caspase-11 expression, which could then activate the CASPASE-1inflammasome. Using chromatin immunoprecipitation (CHIP) and luciferase-based reporter assays, we show that NRF2 directly binds to the Caspase-11 promoter and transcriptionally increase the expression of Caspase-11. Genetic deletion of Caspase-11 in autophagy-deficient livers represses the release of HMGB1 and its pathological consequence, ductular cell proliferation. Consistently, deletion of NLRP3, which can activate CASPASE-1 mediated inflammasomes under other types of signals, did not prevent HMGB1 release and ductular cell proliferation in autophagy deficient livers. Surprisingly, while cleavage of GASDEMIN D occurred in autophagy-deficient livers its deletion did not prevent the HMGB1 release, suggesting that CASPASE-11-mediated inflammasome activation may also engage in a different mechanism for HMGB1 release by the autophagy deficient hepatocytes. Collectively, this work reveals the novel role of NRF2 in transcriptional upregulation of Caspase-11 and in inflammasome activation to promote active release of HMGB via a non-Gasdermin D mediated avenue.