Isorhynchophylline exerts anti-inflammatory and anti-oxidative activities in LPS-stimulated murine alveolar macrophages

Life Sci. 2019 Apr 15;223:137-145. doi: 10.1016/j.lfs.2019.03.017. Epub 2019 Mar 8.

Abstract

Aims: Excessive inflammatory response and oxidative stress are considered as important pathogenic factors in the development of acute lung injury. Isorhynchophylline (IRN), a tetracyclic oxindole alkaloid isolated from Uncaria rhynchophylla, possesses anti-inflammatory and anti-oxidant activities. Our study aimed to investigate the effects and potential mechanisms of IRN on lipopolysaccharide (LPS)-stimulated murine alveolar macrophage cell lines MH-S and NR8383.

Main methods: CCK-8 assay was used to evaluate the cytotoxicity of IRN and LPS. Inflammatory response was assessed by detecting the mRNA expressions and release of tumor necrosis factor α (TNF-α), interleukin (IL)-1β, IL-6, and plasminogen activator inhibitor-1 (PAI-1) using qRT-PCR and ELISA. The expressions of inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2 were examined by qRT-PCR and western blot. Oxidative stress was evaluated by detecting malondialdehyde (MDA) level and the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT). The changes of the toll like receptor (TLR4)/nuclear factor-kappa B (NF-κB)/nod-like receptor protein 3 (NLRP3) inflammasome pathway was detected by western blot.

Key findings: Treatment with LPS or IRN for 24 h showed no cytotoxicity on MH-S and NR8383 cells. IRN pretreatment inhibited LPS-induced production of inflammatory cytokines, expressions of iNOS and COX-2, and oxidative stress in murine alveolar macrophages. Additionally, IRN inhibited LPS-induced activation of TLR4/NF-κB/NLRP3 inflammasome pathway in MH-S cells. Mechanistically, inhibition of TLR4/NF-κB/NLRP3 inflammasome pathway by si-TLR4 suppressed LPS-induced inflammation and oxidative stress in murine alveolar macrophages.

Significance: IRN exerted anti-inflammatory and anti-oxidant effects on LPS-stimulated murine alveolar macrophages via inhibition of the TLR4/NF-κB/NLRP3 inflammasome pathway.

Keywords: Acute lung injury; IRN; Inflammatory response; Oxidative stress; The TLR4/NF-κB/NLRP3 inflammasome pathway.

MeSH terms

  • Animals
  • Anti-Inflammatory Agents / isolation & purification
  • Anti-Inflammatory Agents / pharmacology*
  • Antioxidants / isolation & purification
  • Antioxidants / pharmacology*
  • Cell Line
  • Cell Survival / drug effects
  • Cyclooxygenase 2 / genetics
  • Cytokines / genetics
  • Lipopolysaccharides / pharmacology
  • Macrophages, Alveolar / drug effects*
  • Macrophages, Alveolar / immunology
  • Macrophages, Alveolar / metabolism
  • Mice
  • Nitric Oxide Synthase Type II / genetics
  • Oxidative Stress / drug effects
  • Oxidative Stress / immunology
  • Oxindoles / isolation & purification
  • Oxindoles / pharmacology*
  • Rats
  • Uncaria / chemistry

Substances

  • Anti-Inflammatory Agents
  • Antioxidants
  • Cytokines
  • Lipopolysaccharides
  • Oxindoles
  • rhyncophylline
  • Nitric Oxide Synthase Type II
  • Nos2 protein, mouse
  • Ptgs2 protein, mouse
  • Cyclooxygenase 2