Angiotensin(1-7) attenuated Angiotensin II-induced hepatocyte EMT by inhibiting NOX-derived H2O2-activated NLRP3 inflammasome/IL-1β/Smad circuit

Free Radic Biol Med. 2016 Aug:97:531-543. doi: 10.1016/j.freeradbiomed.2016.07.014. Epub 2016 Jul 18.

Abstract

Epithelial-mesenchymal transition (EMT) is correlated with NAPDH oxidase (NOX)-derived reactive oxygen species (ROS). The ROS-induced NOD-like receptor pyrin domain containing-3 (NLRP3) inflammasome is a novel mechanism of EMT. Angiotensin II (AngII) induces EMT by regulating intracellular ROS. Nevertheless, it has not been reported whether AngII could induce hepatocyte EMT. Angiotensin-(1-7) [Ang-(1-7)] can inhibit the effects of AngII via a counter-regulatory mechanism. However, whether Ang-(1-7) attenuated the effects of AngII on hepatocyte EMT remains unclear. The aim of this study was to determine whether Ang-(1-7) attenuated AngII-induced hepatocyte EMT by inhibiting the NOX-derived ROS-mediated NLRP3 inflammasome/IL-1ß/Smad circuit. In vivo, two animal models were established. In the first model, rats were infused AngII. In the second model, Ang-(1-7) was constantly infused into double bile duct ligated (BDL) rats. In vitro, hepatocytes were pretreated with antioxidant, NLRP3 siRNA, NOX4 siRNA, or Ang-(1-7) before exposure to AngII. In vitro, AngII induced hepatocyte EMT, which was inhibited by N-acetylcysteine (NAC), diphenylene iodonium (DPI), and NOX4 siRNA. NLRP3 inflammasome, which was activated by hydrogen peroxide (H2O2), mediated AngII-induced hepatocyte EMT. Ang-(1-7) suppressed AngII-induced EMT by inhibiting the NOX-derived H2O2-activated NLRP3 inflammasome/IL-1ß/Smad circuit. In vivo, infusion of AngII induced activation of H2O2-correlated NLRP3 inflammasome in rat livers and accumulation of α-collagen I (Col1A1) in hepatocytes. Infusion of Ang-(1-7) alleviated BDL-induced liver fibrosis and inhibited the expression of Col1A1 and the activation of NLRP3 inflammasome in hepatocytes. Ang-(1-7) attenuated AngII-induced hepatocyte EMT by inhibiting the NOX-derived H2O2-activated NLRP3 inflammasome/IL-1ß/Smad circuit.

Keywords: Angiotensin II; Angiotensin-(1–7); Epithelial-mesenchymal transition; Hepatocyte; Liver fibrosis; NADPH oxidase; NLRP3 inflammasome; Reactive oxygen species.

MeSH terms

  • Angiotensin I / pharmacology
  • Angiotensin I / physiology*
  • Angiotensin II / physiology*
  • Animals
  • Cells, Cultured
  • Collagen Type I / genetics
  • Collagen Type I / metabolism
  • Collagen Type I, alpha 1 Chain
  • Epithelial-Mesenchymal Transition*
  • Gene Expression
  • Hepatocytes / physiology*
  • Humans
  • Hydrogen Peroxide / metabolism
  • Inflammasomes / metabolism
  • Interleukin-1beta / metabolism
  • Liver Cirrhosis / metabolism
  • Liver Cirrhosis / pathology
  • Male
  • Mice
  • NADPH Oxidase 4 / metabolism
  • NLR Family, Pyrin Domain-Containing 3 Protein / metabolism
  • Peptide Fragments / pharmacology
  • Peptide Fragments / physiology*
  • Rats, Wistar
  • Signal Transduction*
  • Smad Proteins / metabolism

Substances

  • Collagen Type I
  • Collagen Type I, alpha 1 Chain
  • Inflammasomes
  • Interleukin-1beta
  • NLR Family, Pyrin Domain-Containing 3 Protein
  • NLRP3 protein, human
  • Peptide Fragments
  • Smad Proteins
  • Angiotensin II
  • Angiotensin I
  • Hydrogen Peroxide
  • NADPH Oxidase 4
  • angiotensin I (1-7)