Effect of toll-like receptor 3 agonist poly I:C on intestinal mucosa and epithelial barrier function in mouse models of acute colitis

World J Gastroenterol. 2017 Feb 14;23(6):999-1009. doi: 10.3748/wjg.v23.i6.999.


Aim: To investigate potential effects of poly I:C on mucosal injury and epithelial barrier disruption in dextran sulfate sodium (DSS)-induced acute colitis.

Methods: Thirty C57BL/6 mice were given either regular drinking water (control group) or 2% (w/v) DSS drinking water (model and poly I:C groups) ad libitum for 7 d. Poly I:C was administrated subcutaneously (20 μg/mouse) 2 h prior to DSS induction in mice of the poly I:C group. Severity of colitis was evaluated by disease activity index, body weight, colon length, histology and myeloperoxidase (MPO) activity, as well as the production of proinflammatory cytokines, including tumor necrosis factor-α (TNF-α), interleukin 17 (IL-17) and interferon-γ (IFN-γ). Intestinal permeability was analyzed by the fluorescein isothiocyanate labeled-dextran (FITC-D) method. Ultrastructural features of the colon tissue were observed under electron microscopy. Expressions of tight junction (TJ) proteins, including zo-1, occludin and claudin-1, were measured by immunohistochemistry/immunofluorescence, Western blot and real-time quantitative polymerase chain reaction (RT-qPCR).

Results: DSS caused significant damage to the colon tissue in the model group. Administration of poly I:C dramatically protected against DSS-induced colitis, as demonstrated by less body weight loss, lower disease activity index score, longer colon length, colonic MPO activity, and improved macroscopic and histological scores. It also ameliorated DSS-induced ultrastructural changes of the colon epithelium, as observed under scanning electron microscopy, as well as FITC-D permeability. The mRNA and protein expressions of TJ protein, zo-1, occludin and claudin-1 were also found to be significantly enhanced in the poly I:C group, as determined by immunohistochemistry/immunofluorescence, Western blot and RT-qPCR. By contrast, poly I:C pretreatment markedly reversed the DSS-induced up-regulated expressions of the inflammatory cytokines TNF-α, IL-17 and IFN-γ.

Conclusion: Our study suggested that poly I:C may protect against DSS-induced colitis through maintaining integrity of the epithelial barrier and regulating innate immune responses, which may shed light on the therapeutic potential of poly I:C in human colitis.

Keywords: Dextran sulfate sodium-induced acute colitis; Epithelial barrier disruption; Mucosal injury; Poly I:C; Tight junction.

MeSH terms

  • Animals
  • Colitis, Ulcerative / chemically induced
  • Colitis, Ulcerative / drug therapy*
  • Colitis, Ulcerative / pathology
  • Colon / metabolism*
  • Colon / pathology
  • Colon / ultrastructure
  • Cytokines / metabolism
  • Dextran Sulfate / toxicity
  • Disease Models, Animal
  • Fluorescent Antibody Technique
  • Immunity, Innate / drug effects
  • Immunohistochemistry
  • Injections, Subcutaneous
  • Intestinal Mucosa / metabolism*
  • Intestinal Mucosa / pathology
  • Intestinal Mucosa / ultrastructure
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Microscopy, Electron, Scanning
  • Permeability / drug effects*
  • Peroxidase / metabolism
  • Poly I-C / administration & dosage
  • Poly I-C / pharmacology*
  • Poly I-C / therapeutic use
  • Real-Time Polymerase Chain Reaction
  • Severity of Illness Index
  • Tight Junction Proteins / metabolism
  • Toll-Like Receptor 3 / agonists*
  • Weight Loss / drug effects


  • Cytokines
  • TLR3 protein, mouse
  • Tight Junction Proteins
  • Toll-Like Receptor 3
  • Dextran Sulfate
  • Peroxidase
  • Poly I-C