Macrophage-Derived Il-1 Alpha Promotes Sterile Inflammation In A Mouse Model Of Acetaminophen Hepatotoxicity

The metabolic intermediate of acetaminophen (APAP) can cause severe hepatocyte necrosis, which triggers aberrant immune activation of liver non-parenchymal cells (NPC). Overzealous hepatic inflammation determines the morbidity and mortality of APAP-induced liver injury (AILI). Interleukin-1 receptor (IL-1R) signaling has been shown to play a critical role in various inflammatory conditions, but its precise role and underlying mechanism in AILI remain debatable. Herein, we show that NLRP3 inflammasome activation of IL-1 beta is dispensable to AILI, whereas IL-1 alpha, the other ligand of IL-1R1, accounts for hepatic injury by a lethal dose of APAP. Furthermore, Kupffer cells function as a major source of activated IL-1a in the liver, which is activated by damaged hepatocytes through TLR4/MyD88 signaling. Finally, IL-1 alpha is able to chemoattract and activate CD11b(+) Gr-1(+) myeloid cells, mostly neutrophils and inflammatory monocytes, to amplify deteriorated inflammation in the lesion. Therefore, this work identifies that MyD88-dependent activation of IL-1 alpha in Kupffer cells plays a central role in the immunopathogenesis of AILI and implicates that IL-1 alpha is a promising therapeutic target for AILI treatment.