P0173 The impact of dietary composition on metallothionein gene expression in the intestinal epithelium by exclusive enteral nutrition

Abstract Background The mechanism by which exclusive enteral nutrition (EEN) is effective in the treatment of Crohn’s disease remains elusive. Epidemiologic studies have shown that a substantial proportion of patients with Crohn’s disease are deficient in micronutrients such as zinc, which has been shown to play an important role in the integrity of intestinal epithelial barrier function. Zinc plays a critical role in the transcriptional regulation of metallothioneins (MT), cysteine rich binding proteins that regulate both epithelial and immune function where they are generally believed to play a beneficial role in reducing disease. Methods Transcriptomic analyses were performed by both bulk RNAseq as well as GeoMx spatial transcriptomics. Enzymatic food digests using both bile acids and pancreatic enzymes, analyzed by Proton NMR metabolomics, were used to generate cell culture media for studies in intestinal epithelial cells. Results RNAseq of rectal biopsies obtained from healthy human subjects consuming EEN (Modulen-IBD, Nestlé Health Science) vs. an omnivore diet revealed a very specific induction of genes involved in mineral transport, namely MTs such as MT1G and MT2A. Spatial transcriptomics revealed that the induction of MTs was specific to the colonic epithelium. To develop a cellular model to characterize the mechanism underlying this response, we investigated the impact of animal protein, vegetable, and EEN based foods on the transcriptome of intestinal epithelial cells in culture by both RNAseq and targeted quantitative RT-PCR. This model involved the development of a physiologically relevant modality to digest whole food to generate serum-free cell culture media that was characterized using NMR-based metabolomics. Animal protein and EEN diets induced the expression of specific MTs whereas vegetable diets reduced their expression. We also show that zinc induced MT gene expression in intestinal epithelial cells whereas phytic acid, a phytochemical with known anti-nutrient properties that chelates zinc, reduces the ability of protein-based foods and EEN to induce MT gene expression. Conclusion The consumption of EEN leads to a very specific transcriptomic signature of MT gene expression in the rectal epithelium of humans that can be reproduced in cell culture by exposure to both animal protein-based foods and EEN. By contrast, vegetable-based foods inhibit MT gene expression possibly through the chelation of zinc. These results are consistent with the notion that the exclusion of plant-based foods through the consumption of EEN may have beneficial effects in the treatment of Crohn’s disease by reducing exposure to anti-nutrient phytochemicals that reduce the absorption of beneficial micronutrients such as zinc.