Casein Glycomacropeptide Regulates Gene Expression in Intestinal Epithelial Cells: Effect of Simulated Gastrointestinal Digestion and Peptide Microencapsulation

Abstract

κ-Casein glycomacropeptide (GMP) exerts anti-inflammatory and immune modulatory effects. A bovine GMP concentrate and its in vitro digestion product were obtained. GMP was also microencapsulated with phycocolloids and further digested. These products were tested in three-dimensional (3D) and open monolayer two-dimensional (2D) mouse jejunal organoids. Almost no effect was observed on the 2D organoids. In 3D organoids, GMP induced intestinal proliferation (Axin2, Pcna) and differentiation (Vil1, Alpl) genes together with Muc3, antibacterial genes (Lyz1, Pla2g2a), and Cxcl1. GMP also induced interferon I defense genes (Ifnb1, Ifr3, Oas2, Oas3, Rnasel) under basal conditions and in TNF-stimulated organoids. In vitro digestion abrogated the effects of GMP and induced new genes (Lgr5, Olfm4, and Lct). In TNF-stimulated organoids, digested GMP repressed multiple genes. Encapsulation largely preserved the GMP effects. In conclusion, GMP showed differential effects in 3D and 2D organoids. The effects of digestion peptides were also different, suggesting distinct potential as functional foods.

Keywords: casein glycomacropeptide; dialyzability; encapsulation by spray drying; in vitro gastrointestinal digestion; intestinal epithelial cells; intestinal organoids.

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FPLC profiles of WPC and GMPe (A); RP-HPLC profile of GMPe (B); scanning electron micrographs of GMPe-C (C); surface hydrophobicity of BC, GMPe-C, GMPe-C + NaCl (10 mmol L^–1) and GMPe-C + SDS (0.25%) (D); and RP-HPLC profiles of GMPe-D and GMPe-C–D (E). Different letters mean significant differences between samples (P < 0.05).

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Expression of genes involved in the intestinal barrier function y mouse jejunum 3D and 2D organoids measured by different letters indicate different values p < 0.05. Data are representative of two different experiments, n = 4.

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Expression of goblet and Paneth cell markers in 3D mouse jejunum organoids measured by qRT-PCR. Different letters indicate different values p < 0.05. Data are representative of two different experiments, n = 4.

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Expression interferon response genes in mouse jejunum 3D organoids measured by qRT-PCR. Different letters indicate different values p < 0.05. Data are representative of two different experiments, n = 4.

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Expression of proliferation-related genes in mouse jejunum 3D organoids measured by qRT-PCR. Different letters indicate different values p < 0.05. Data are representative of two different experiments, n = 4.

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Expression of enterocyte genes in mouse jejunum 3D organoids measured by qRT-PCR. Different letters indicate different values p < 0.05. Data are representative of two different experiments, n = 4.

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Expression of Cxcl1 and interferon-related genes in 3D mouse jejunum organoids measured by qRT-PCR. Different letters indicate different values p < 0.05. Data are representative of two different experiments, n = 4.