title: Blockade of Notch signaling promotes acetaminophen-induced liver injury.
abstract: Liver injury after experimental acetaminophen treatment is mediated both by direct hepatocyte injury through a P450-generated toxic metabolite and indirectly by activated liver Kupffer cells and neutrophils. This study was designed to investigate the role of Notch signaling in the regulation of innate immune responses in acetaminophen (APAP)-induced liver injury. Using a mouse model of APAP-induced liver injury, wild-type (WT) and toll-like receptor 4 knockout (TLR4 KO) mice were injected intraperitoneally with APAP or PBS. Some animals were injected with γ-secretase inhibitor DAPT or DMSO vehicle. For the in vitro study, bone marrow-derived macrophages (BMMs) were transfected with Notch1 siRNA, TLR4 siRNA, and non-specific (NS) siRNA and stimulated with LPS. Indeed, paracetamol/acetaminophen-induced liver damage was worse after Notch blockade with DAPT in wild-type mice, which was accompanied by significantly increased ALT levels, diminished hairy and enhancer of split-1 (Hes1), and phosphorylated Stat3 and Akt but enhanced high mobility group box 1 (HMGB1), TLR4, NF-κB, and NLRP3 activation after APAP challenge. Mice receiving DAPT increased macrophage and neutrophil accumulation and hepatocellular apoptosis. However, TLR4 KO mice that received DAPT reduced APAP-induced liver damage and NF-κB, NLRP3, and cleaved caspase-1 activation. BMMs transfected with Notch1 siRNA reduced Hes1 and phosphorylated Stat3 and Akt but augmented HMGB1, TLR4, NF-κB, and NLRP3. Furthermore, TLR4 siRNA knockdown resulted in decreased NF-κB and NLRP3 and cleaved caspase-1 and IL-1β levels following LPS stimulation. These results demonstrate that Notch signaling regulates innate NLRP3 inflammasome activation through regulation of HMGB1/TLR4/NF-κB activation in APAP-induced liver injury. Our novel findings underscore the critical role of the Notch1-Hes1 signaling cascade in the regulation of innate immunity in APAP-triggered liver inflammation. This might imply a novel therapeutic potential for the drug-induced damage-associated lethal hepatitis.
authors.affiliation: Department of Infectious Diseases, the First Affiliated Hospital, Nanjing Medical University, Nanjing, China.|The Dumont-UCLA Transplant Center, Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
authors.forename: Longfeng
authors.initials: L
authors.lastname: Jiang
authors.affiliation: The Dumont-UCLA Transplant Center, Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Ke
authors.affiliation: Department of Stem Cell Biology and Regenerative Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.
authors.forename: Shi
authors.initials: S
authors.lastname: Yue
authors.affiliation: School of Life Science and Technology, China Pharmaceutical University, Nanjing, China.
authors.forename: Wen
authors.initials: W
authors.lastname: Xiao
authors.affiliation: Department of Infectious Diseases, the First Affiliated Hospital, Nanjing Medical University, Nanjing, China.
authors.forename: Youde
authors.initials: Y
authors.lastname: Yan
authors.affiliation: School of Life Science and Technology, China Pharmaceutical University, Nanjing, China.
authors.forename: Xiaozhao
authors.initials: X
authors.lastname: Deng
authors.affiliation: Department of Stem Cell Biology and Regenerative Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.
authors.forename: Qi-Long
authors.initials: QL
authors.lastname: Ying
authors.affiliation: Department of Infectious Diseases, the First Affiliated Hospital, Nanjing Medical University, Nanjing, China. dr-lijun@vip.sina.com.
authors.forename: Jun
authors.initials: J
authors.lastname: Li
authors.affiliation: The Dumont-UCLA Transplant Center, Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA. bke@mednet.ucla.edu.
authors.forename: Bibo
authors.identifier: 0000-0002-1885-1538
authors.initials: B
authors.lastname: Ke
mesh_terms: D000082:Acetaminophen / Q000009:adverse effects* / Q000627:therapeutic use; D000818:Animals; D002478:Cells, Cultured; D056486:Chemical and Drug Induced Liver Injury / Q000276:immunology*; D004195:Disease Models, Animal; D024243:HMGB1 Protein / Q000378:metabolism; D022781:Hepatocytes / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D007113:Immunity, Innate; D008264:Macrophages / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D016328:NF-kappa B / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D051881:Receptor, Notch1 / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D051197:Toll-Like Receptor 4 / Q000235:genetics; D000072056:Transcription Factor HES-1 / Q000378:metabolism*
chemical_list: D024243:HMGB1 Protein; C489734:Hes1 protein, mouse; D016328:NF-kappa B; D034741:RNA, Small Interfering; D051881:Receptor, Notch1; D051197:Toll-Like Receptor 4; D000072056:Transcription Factor HES-1; D000082:Acetaminophen
keywords: DAPT; HMGB1; Hes1; Liver inflammation; Notch; TLR4