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Crucial role of milk proteins on adhesion of intestinal microbes

Abstract : Milk is a complex biological matrix that has evolved as the source of nutrition and natural immunological protection for neonate [1,2]. It is the most popular matrix for the delivery of probiotic bacteria such as Lactobacillus, Bifidobacterium, that are widely known for their beneficial effects on human health. The different dairy components including proteins and fat globules (especially the Milk Fat Globule Membrane, MFGM) were actively studied in relation to their anti-adhesive properties against food pathogens. However, interaction between probiotic bacteria and dairy can also occur thus modulating the bacterial adhesion to intestinal cells which is a crucial step for the expression of health-related positive effects. Mechanisms and biomolecules involved in bacterial adhesive interactions with food components have been studied more recently [3,4,5,6]. These interactions are likely to play a role in bacterial viability, spatial distribution, and behavior during the structuration of food products. In the present work, interactions between two strains of Lactobacillus rhamnosus GG (i.e. wild-type and mutant pili-depleted), and two intestinal epithelial cells: HT29 CL16E cells producing mucus and Caco-2 TC7 cells with two milk glycoproteins (GPs) (i.e Lactoferrin and Osteopontin) were studied. Lactoferrin (LF) and osteopontin (OPN) are both multi-functional whey proteins. LF is a basic glycoprotein while OPN is an acidic phosphorylated glycoprotein. These two GPs mostly act by binding to surface receptors and they are known to prevent some intestinal diseases and other several chronic intestinal inflammation (Crohn's disease, multiple sclerosis) [3,7]. Differentiated intestinal cells were obtained after a 22 days culture. Bacteria were grown in MRS broth and were recovered by centrifugation (3000 g, 10 min). The cell plate (epithelial cells) was washed several times before the addition of bacterial suspension. After incubation (2h, 37 °C), all wells were inoculated for bacterial counting. The number of bacteria adhered per cell was reported. Two cases were explored: with or without a pre-incubation with the milk GP (OPN or LF). In each case, GPs improved the adhesion of bacteria (piliated or not) to epithelial cells. The difference in adhesion between the wild-type strain and the mutant (pili-depleted strain) without GPs is attributed to the pilus that has a key role in adhesion of LGG to epithelial intestinal cells [5]. In the presence of GPs, the adhesion was improved for bacteria on epithelial cells but this adhesion has much more impact when the epithelial cells produce mucus (i.e HT29). It can be concluded that, the bacterial adhesion to intestinal cells depends on the type of intestinal cells (ability to produce mucus), and the interaction can be modulated by the food matrix as some GPs can improve the adhesion (OPN, LF) while others can decrease it (dairy mucins, β-Lactoglobulin). These results would therefore lead to future manipulations such as the identification of molecules potentially involved in cell adhesions (i.e adhesins, GPs, peptides, surface molecules of intestinal cells).
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https://hal.univ-lorraine.fr/hal-02504336
Contributor : Sarah Barrau <>
Submitted on : Tuesday, March 10, 2020 - 4:14:18 PM
Last modification on : Tuesday, March 17, 2020 - 3:04:28 AM

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Sarah Barrau, C. Gaiani, Claire Retourney, C. Mangavel, Yves Le Roux, et al.. Crucial role of milk proteins on adhesion of intestinal microbes. Biomolecules: Research & Development, Markets and Acceptability, Oct 2019, Palma de Majorque, Spain. ⟨hal-02504336⟩

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