J Crohns Colitis 2017 Feb 29;11(2):237-245. Epub 2016 Jul 29.
Cattedra di Gastroenterologia, Dipartimento di Medicina dei Sistemi, Università Tor Vergata, Rome, Italy.
Background And Aim: Environmental factors are supposed to play a decisive role in the pathogenesis of inflammatory bowel diseases [IBDs]. Increased dietary salt intake has been linked with the development of autoimmune diseases, but the impact of a salt-enriched diet on the course of IBD remains unknown. In this study, we examined whether high salt intake alters mucosal cytokine production and exacerbates colitis.
Methods: Normal intestinal lamina propria mononuclear cells [LPMCs] were activated with anti-CD3/CD28 in the presence or absence of increasing concentrations of sodium chloride [NaCl] and/or SB202190, a specific inhibitor of p38/MAP Kinase. For in vivo experiments, a high dose of NaCl was administered to mice 15 days before induction of trinitrobenzene-sulfonic acid [TNBS]-colitis or dextran sulfate sodium [DSS]-colitis. In parallel, mice were given SB202190 before induction of TNBS-colitis. Transcription factors and effector cytokines were evaluated by flow-cytometry and real-time PCR.
Results: IL-17A, IL-23R, TNF-α, and Ror-γT were significantly increased in human LPMCs following NaCl exposure, while there was no significant change in IFN-γ, T-bet or Foxp3. Pharmacologic inhibition of p38/MAPK abrogated the NaCl-inducing effect on LPMC-derived cytokines. Mice receiving the high-salt diet developed a more severe colitis than control mice, and this effect was preventable by SB202190.
Conclusions: Our data indicated that exposure of intestinal mononuclear cells to a high-NaCl diet enhanced effector cytokine production and contributed to the exacerbation of experimental colitis in mice.