TGR5 agonist INT-777 mitigates inflammatory response in human endometriotic stromal cells: A therapeutic implication for endometriosis

Int Immunopharmacol. 2019 Jun:71:93-99. doi: 10.1016/j.intimp.2019.02.044. Epub 2019 Mar 14.

Abstract

Endometriosis is a condition characterized by the presence of endometrial tissues outside the uterus. Endometriotic stromal cells (ESCs) are known to undergo regeneration and are linked to the causation of endometriosis. Activation of stromal cells by local inflammatory cytokines is proposed to be one of the mechanisms of endometriosis development. Takeda-G-protein-receptor-5 (TGR5) is a G protein-coupled bile acid receptor that plays multiple roles in various cells and tissues. In this study, we show that activation of TGR5 by its specific agonist, INT-777, protects ESCs from inflammation and oxidative stress induced by tumor necrosis factor-α (TNF-α). TGR5 is fairly expressed in cultured ESCs, and TNF-α treatment suppresses TGR5 expression. Activation of TGR5 by its synthetic agonist, INT-777, dramatically reduces the production of pro-inflammatory cytokines and adhesion molecules by TNF-α, including interleukin-6 (IL-6), interleukin-8 (IL-8), monocyte chemoattractant protein-1 (MCP-1), intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1). Moreover, INT-777 suppresses TNF-α-induced NADPH oxidase 4 (NOX4) expression and ameliorates cellular oxidative stress. Mechanistically, our findings demonstrate that INT-777 suppresses TNF-α-induced c-Jun N-terminal kinase (JNK) activation via suppression of p-JNK. INT-777 inhibits TNF-α-induced activation of the activator protein-1 (AP-1) pathway owing to its suppression of c-Jun and c-fos as well as transfected AP-1 promoter. INT-777 also inhibits nuclear factor-κB (NF-κB) activation as revealed by its suppression of TNF-α-induced nuclear p65 accumulation and NF-κB promoter. Collectively, our data indicate that activation of TGR5 by its agonist has protective effects against inflammation and reactive oxygen species (ROS) in cytokine-induced activation of ESCs. Therefore, INT-777 may have an implication in the clinical treatment of endometriosis.

Keywords: AP-1; Endometriotic stromal cells (ESCs); INT-777; JNK; NF-κB; TGR5; TNF-α.

MeSH terms

  • Cell Adhesion Molecules / metabolism
  • Cell Line
  • Cholic Acids / pharmacology
  • Cholic Acids / therapeutic use*
  • Endometriosis / drug therapy*
  • Endometrium / pathology*
  • Female
  • Humans
  • Inflammation
  • Inflammation Mediators / metabolism
  • MAP Kinase Kinase 4 / metabolism
  • NADPH Oxidase 4 / metabolism
  • NF-kappa B / metabolism
  • Oxidative Stress
  • Receptors, G-Protein-Coupled / agonists*
  • Signal Transduction
  • Stromal Cells / physiology*
  • Transcription Factor AP-1 / genetics
  • Transcription Factor AP-1 / metabolism
  • Tumor Necrosis Factor-alpha / metabolism

Substances

  • 6alpha-ethyl-23(S)-methylcholic acid
  • Cell Adhesion Molecules
  • Cholic Acids
  • GPBAR1 protein, human
  • Inflammation Mediators
  • NF-kappa B
  • Receptors, G-Protein-Coupled
  • Transcription Factor AP-1
  • Tumor Necrosis Factor-alpha
  • NADPH Oxidase 4
  • MAP Kinase Kinase 4