The food additive EDTA increases intestinal inflammation and colorectal carcinogenesis by disrupting the intestinal epithelial barrier

Food additives may constitute an environmental factor for IBD. We have shown that the chelator EDTA used as a stabilizing agent or iron fortificant aggravates gut inflammation and colitis-associated cancer (CAC). We propose that EDTA's toxicity is conferred by disruption of the epithelial barrier. We used intestinal tissue from mice (azoxymethane/dextran sodium sulphate-treated or IL10-/-) fed with EDTA salts or control diet. E-cadherin and beta-catenin were analyzed by immunohistochemistry and the mucus layer by PAS-staining. The data are presented as an immunoreactivity (IRS) score ranging from 0 – 100%. The direct action of EDTA was studied on T84 mouse intestinal cell monolayers. FITC-dextran paracellular permeability was assessed photometrically. The cell contacts upon EDTA were examined by immunofluorescence. Upon EDTA treatment, we observed a loss of membranous beta-catenin (median IRS (range); control vs. EDTA: AOM/DSS 72%(60 – 80) vs. 53%(45 – 80), p < 0.001; IL10-/-: 78% (58 – 95) vs. 65% (43 – 80); p = 0.101) and a trend in E-cadherin reduction (AOM/DSS: 64% (54 – 84) vs. 59% (48 – 73), p = 0.378; IL10-/-: 68% (53 – 85) vs. 58% (48 – 88), p = 0.227) as well as an increase in cytoplasmic E-cadherin (AOM/DSS: 8% (5 – 15) vs. 11% (5 – 33), p = 0.022; IL10-/-: 4% (3 – 8) vs. 10% (5 – 25), p = 0.001) in the distal colon; the effect was diminishing proximally. The mucus layer exhibited more breeches with EDTA (AOM/DSS: 78% (65 – 80) vs. 70% (35 – 80), p = 0.148; IL10-/-: 80% (75 – 90) vs. 65% (40 – 85), p = 0.018). Treatment of T84 monolayers with EDTA increased paracellular permeability, and this was more pronounced after pretreatment with TNFa and IFNg. Immunofluorescence demonstrated disruption of tight and adherens junctions and desmosomes. EDTA disrupts various components of the epithelial barrier, probably by chelating Ca2+ and Mg2+ necessary for maintenance of these structures. This may constitute the mechanism by which EDTA increases intestinal inflammation and CAC development. Inflammation augments the effect, possibly explaining why EDTA toxicity is only evident in colitis but not in healthy animals. There is an underestimated hazard of food additives regarding IBD and CAC.