Intestinal Epithelial Cell Proteome from Wild-Type and TNF^ΔARE/WT Mice: Effect of Iron on the Development of Chronic Ileitis

Abstract

Environmental factors substantially contribute to the development of chronic intestinal inflammation in the genetically susceptible host. Nutritional components like iron may act as pro-oxidative mediators affecting inflammatory processes and cell stress mechanisms. To better characterize effects of dietary iron on epithelial cell responses under the pathological conditions of chronic intestinal inflammation, we characterized the protein expression profile (proteome) in primary intestinal epithelial cells (IEC) from iron-adequate and low-iron fed wild-type (WT) and TNFDeltaARE/WT mice. We performed all possible comparisons between the 4 groups according to genotype or diet. Histological analysis of iron-adequate fed TNFDeltaARE/WT mice (approximately 0.54 mg of iron/day) revealed severe ileal inflammation with a histopathology score of 8.3+/-0.91 (score range from 0-12). Interestingly, low-iron fed mice (approximately 0.03 mg of iron/day) were almost completely protected from the development of inflammatory tissue destruction (histopathology score of 2.30+/-0.73). In total, we identified 74 target proteins with significantly altered steady state expression levels in primary IEC using 2D-gel electrophoresis (2D SDS-PAGE) and peptide mass fingerprinting via MALDI-TOF mass spectrometry (MS). Interestingly, the overlap between the comparison of iron-adequate fed WT and TNFDeltaARE/WT mice (inflamed conditions) and the comparison between the iron-adequate and iron-low fed TNFDeltaARE/WT mice (absence of inflammation) revealed 4 contrarily regulated proteins including aconitase 2, catalase, intelectin 1 and fumarylacetoacetate hydrolase (FAH). These proteins are associated with energy homeostasis, host defense, oxidative and endoplasmic reticulum (ER) stress responses. In conclusion, the iron-low diet affected the epithelial cell proteome and inhibited the development of chronic intestinal inflammation, suggesting a critical role for nutritional factors in the pathogenesis of IBD.

Depletion of luminal iron alters the gut microbiota and prevents Crohn's disease-like ileitis

“…Functional proteome analysis of primary ileal IECs from wild-type (WT) and TNF ∆ARE/WT mice fed an iron sulfate containing diet or iron sulfate free diet revealed significant differences in the regulation of proteins participating in energy metabolism and stress responses when comparing inflamed with non-inflamed conditions 10. In this study, we used heterozygous TNF ∆ARE/WT mice to investigate the mechanistic role of both luminal iron sulfate and systemic iron in the development of chronic ileitis in a model of Crohn's disease focussing on the effect of iron status on ER stress regulation and changes in gut microbial ecology.…”

Equivalent Effects on Fecal Reactive Oxygen Species Generation with Oral Supplementation of Three Iron Compounds: Ferrous Sulfate, Sodium Iron EDTA and Iron Polymaltose

“…Iron-induced oxidative stress in the intestinal lumen showed far-reaching metabolic consequences in a murine model of Crohn’s disease [28,29]. It induces endoplasmic reticulum stress, i.e.…”

Berberine Ameliorates Pro-inflammatory Cytokine-Induced Endoplasmic Reticulum Stress in Human Intestinal Epithelial Cells In Vitro

“…Clinical study revealed that targeted therapy against TNF-α could downregulate epithelial cell apoptosis and promotes barrier repair in active Crohn's disease [26]. Mutant mouse with TNF-α overexpression may cause IEC FFA (fumarylacetoacetate) accumulation [27], which has been proven as a potent inducer of ER stress [28]. Since whether TNF-α alone could induce ER stress and apoptosis is controversial in vitro [29], and previous studies revealed that IFN-γ prime the response of Caco-2 cells to TNF-α through induction of TNFR2 expression [15] or potentiating TNF-related apoptosis-inducing ligand [30], a combination of IFN-γ and TNF-α was used.…”