Alleviation of Intestinal Inflammation by Dietary Pomegranate Extract Supplementation in Mice

OBJECTIVES: Inflammatory bowel disease (IBD) results from a complex interaction among host, microbial and environmental factors. Among these, diet has emerged as an important and actionable modifier of IBD activity. Pomegranate major bioactive metabolites, ellagic acid and urolithins, have been shown to improve symptoms of IBD in chemically induced mouse models of colitis. Here, we aim to test the hypothesis that dietary pomegranate extract (PomX) supplementation will reduce the development of colitis in IL-10 knock out (IL-10(−/−)) mice, which spontaneously develop chronic colitis after birth. METHODS: 4 week old male IL-10(−/−) mice were randomly assigned to a high fat high sucrose (HFHS) diet, or to a HFHS diet supplemented with 0.25% PomX for 8 weeks. At the end of the experiment, the mice were euthanized and intestinal tissues were isolated and frozen for RNA extraction, or fixed for histologic analysis. Plasma samples were collected and processed for lipocalin 2 assay. RESULTS: Histomorphological analysis of colonic tissues revealed lower histological scores in HFHS-PomX fed mice, 3.9 ± 1.0 vs. 2.6 ± 0.5 in HFHS fed mice (n = 8, P = 0.02). In addition, signs of rectal prolapse were observed in 62.5% of IL-10(−/−) mice in the HFHS group vs. 12.5% in the HFHS/PomX group (P = 0.04). RNAseq and bioinformatic analysis, obtained from the colonic tissues (n = 4 mice/each group), showed in PomX treated mice a downregulation of 483 genes and an upregulation of 263 genes. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) and Reactome analyses showed that PomX downregulated genes which are mainly associated with immune inflammatory responses, defenses, and neutrophil degranulation, including IL1α, IL6 and TNFα pro-inflammatory cytokines. Spleen weights were lower in HFHS-PomX treated mice as compared to HFHS fed control mice (P = 0.04). In addition, PomX treated mice showed a trend of higher body weights (∼13%) and lower lipocalin 2 plasma levels (∼46%) as compared to HFHS fed mice. CONCLUSIONS: Our data demonstrated that PomX supplementation decreased colitis symptoms and lowered the inflammatory parameters of colitis in HFHS fed IL10(−/−) mice. These data support the anti-inflammatory effects of dietary PomX supplementation that were previously observed in the DSS colitis murine model. FUNDING SOURCES: This project was supported by UCLA Center for Human Nutrition.