The Effect of a Fennel Extract on the STAT Signaling and Intestinal Barrier Function

Background: Foeniculum vulgare, F. vulgare, commonly known as fennel, is believed to be one of the worlds oldest medicinal herbs and has been exploited by people for centuries as a nutritional aid for digestive disorders. In many southeast Asian countries it is ingested as an after-meal snack, mukhvas, due to its breath-freshening and digestive aid properties. F. vulgare is used in some countries, such as Iran, as a complementary and alternative treatment for inflammatory bowel disease (IBD). Methods: This study investigated the effects of F. vulgare on the barrier function of the intestinal epithelium Signal Transducer and Activator of Transcription (STAT) pathway, which is active in inflammatory bowel disease. To study the protective effects of F. vulgare extract in vitro, monolayers derived from the T84 colonic cell line were challenged with interferon-gamma (IFN-γ) and monitored with and without F. vulgare extract. To complement our in vitro studies, the dextran sodium sulfate induced murine colitis model was employed to ascertain whether the protective effect of F. vulgare extract can be recapitulated in vivo. Results: F. vulgare extract was shown to exert a protective effect on TEER in both T84 and murine models and showed increases in tight junction-associated mRNA in T84 cell monolayers. Both models demonstrated significant decreases in phosphorylated STAT1 (pSTAT1), indicating reduced activation of the STAT pathway. Additionally, mice treated with F. vulgare showed significantly lower ulcer indices than control mice. Conclusions: We conclude barrier function of the gastrointestinal tract is improved by F. vulgare, suggesting the potential utility of this agent as an alternative or adjunctive therapy in IBD.