Anti-inflammatory effects of pomegranate (Punica granatum L.) husk ellagitannins in Caco-2 cells, an in vitro model of human intestine

Food Funct. 2012 Aug;3(8):875-85. doi: 10.1039/c2fo10258g. Epub 2012 Jun 26.

Abstract

This study aimed at evaluating the anti-inflammatory properties of a pomegranate fruit husk (PomH) polyphenolic extract, rich in punicalagin, using Caco-2 cells, an in vitro model of human intestinal epithelium. Differentiated cells in bicameral inserts were pretreated or not with a PomH extract or punicalagin, as reference, at the apical side, representing the intestinal lumen. Inflammation was then induced with a cocktail of cytokines (Il-1β, TNFα and IFNγ) and LPS. After 24 h incubation, 3 pro-inflammatory markers, i.e., interleukin (IL)-6, IL-8 and monocyte chemoattractant protein (MCP)-1, were assayed both at their gene transcription (qRT-PCR) and secretion (ELISA) levels. As previously described, the pro-inflammatory cocktail significantly stimulated these 3 markers, at the gene transcript and secretion levels. In inflamed cells, a significant down-regulation of the transcription of the genes encoding IL-6 and MCP-1 was observed in the presence of the PomH extract or punicalagin, while IL-8 transcription was unaffected. Both treatments also decreased the amounts of the 3 proteins with dose-response effects, but only in the apical compartment. A lowered ELISA response was also observed when either IL-6, IL-8 or MCP-1 were mixed with punicalagin in a cell-free culture medium, indicating a direct molecular interaction. In conclusion, the punicalagin-rich PomH extract tested showed anti-inflammatory properties in the Caco-2 in vitro intestinal model. It acted both on the pro-inflammatory gene transcription and protein levels, the later phenomenon being possibly due to a direct molecular trapping. These data suggest that pomegranate husk could be an interesting natural source contributing to prevent intestinal chronic inflammation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Inflammatory Agents / administration & dosage*
  • Caco-2 Cells
  • Chemokine CCL2 / analysis
  • Chemokine CCL2 / genetics
  • Cytokines
  • Down-Regulation
  • Humans
  • Hydrolyzable Tannins / administration & dosage*
  • Inflammatory Bowel Diseases / chemically induced
  • Inflammatory Bowel Diseases / prevention & control*
  • Interleukin-6 / analysis
  • Interleukin-6 / genetics
  • Interleukin-8 / analysis
  • Interleukin-8 / genetics
  • Intestines / chemistry
  • Intestines / drug effects
  • Lipopolysaccharides
  • Lythraceae / chemistry*
  • Phytotherapy

Substances

  • Anti-Inflammatory Agents
  • CCL2 protein, human
  • Chemokine CCL2
  • Cytokines
  • Hydrolyzable Tannins
  • Interleukin-6
  • Interleukin-8
  • Lipopolysaccharides
  • punicalagin