Commercial dairy cow milk microRNAs resist digestion under simulated gastrointestinal tract conditions

Authors: Benmoussa, AbderrahimLee, Chan Ho C.Laffont, BenoitSavard, PatriciaLaugier, JonathanBoilard, ÉricGilbert, CarolineFliss, IsmaïlProvost, Patrick
Abstract: Background: MicroRNAs are small, gene-regulatory noncoding RNA species present in large amounts in milk, where they seem to be protected against degradative conditions, presumably because of their association with exosomes. Objective: We monitored the relative stability of commercial dairy cow milk microRNAs during digestion and examined their associations with extracellular vesicles (EVs). Methods: We used a computer-controlled, in vitro, gastrointestinal model TNO intestinal model-1 (TIM-1) and analyzed, by quantitative polymerase chain reaction, the concentration of 2 microRNAs within gastrointestinal tract compartments at different points in time. EVs within TIM-1 digested and nondigested samples were studied by immunoblotting, dynamic light scattering, quantitative polymerase chain reaction, and density measurements. Results: A large quantity of dairy milk Bos taurus microRNA-223 (bta-miR-223) and bta-miR-125b (∼109–1010 copies/300 mL milk) withstood digestion under simulated gastrointestinal tract conditions, with the stomach causing the most important decrease in microRNA amounts. A large quantity of these 2 microRNAs (∼108–109 copies/300 mL milk) was detected in the upper small intestine compartments, which supports their potential bioaccessibility. A protocol optimized for the enrichment of dairy milk exosomes yielded a 100,000 × g pellet fraction that was positive for the exosomal markers tumor susceptibility gene-101 (TSG101), apoptosis-linked gene 2–interacting protein X (ALIX), and heat shock protein 70 (HSP70) and containing bta-miR-223 and bta-miR-125b. This approach, based on successive ultracentrifugation steps, also revealed the existence of ALIX−, HSP70−/low, and TSG101−/low EVs larger than exosomes and 2–6 times more enriched in bta-miR-223 and bta-miR-125b (P < 0.05). Conclusions: Our findings indicate that commercial dairy cow milk contains numerous microRNAs that can resist digestion and are associated mostly with ALIX−, HSP70−/low, and TSG101−/low EVs. Our results support the existence of interspecies transfer of microRNAs mediated by milk consumption and challenge our current view of exosomes as the sole carriers of milk-derived microRNAs.
Document Type: Article de recherche
Issue Date: 5 October 2016
Open Access Date: Restricted access
Document version: VoR
This document was published in: The Journal of Nutrition, Vol. 146 (11), 2206–2215 (2016)
Charles C. Thomas, Publisher
Alternative version: 10.3945/jn.116.237651
Collection:Articles publiés dans des revues avec comité de lecture

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