RNase H2-Dependent Polymerase Chain Reaction and Elimination of Confounders in Sample Collection, Storage, and Analysis Strengthen Evidence That microRNAs in Bovine Milk Are Bioavailable in Humans

Abstract

Confounders in plasma miR analysis include the use of heparin tubes, erythrocyte hemolysis, and storage of thawed plasma at room temperature. rhPCR is a useful tool to detect dietary miRs.

Milk MicroRNAs in Health and Disease

“…On the contrary to other fields, in milk microRNA studies, “the absorption/assimilation into intestinal epithelium cells as well as the presystemic, intestinal, and hepatic metabolism” of microRNAs is considered part of the bioavailability of milk microRNAs (Benmoussa et al., ; Cardoso et al., ; Lyng et al., ; Ting et al., ; Tome‐Carneiro et al., ; Wang et al., ). Moreover, for milk microRNAs, bioavailability does not include their function but only their internalization and detection within the circulatory system or in different organs of the consumer (Manca et al., ; Wang et al., ; Wolf, Baier, & Zempleni, ; Zempleni et al., ). Functions of milk microRNAs are usually referred to as bioactivity (Benmoussa et al., ; Melnik et al., ; Yu, Zhao, Sun, & Li, ; Zempleni, ), and it would require a minimum of 1,000 copies of microRNAs to exert a biological function inside a cell (Williams et al., ).…”

“…It is also of interest to study their impact in infant development in the context of infant formulas, which are poor in microRNAs (Alsaweed et al., ; Chen et al., ; Oh, Park, Son, & Kim, ), for newborns not fed with maternal milk (Oh et al., ; Zempleni et al., 2016). Finally, as for infants, the relevance of their biological function in adult consumers is also under investigation and remains up for debate (Auerbach, Vyas, Li, Halushka, & Witwer, ; Baier, Xie, & Zempleni, ; Cui & Zempleni, ; Cui et al., ; Manca et al., ; Melnik, John, Carrera‐Bastos, & Schmitz, ; Wang, Sadri, Giraud, & Zempleni, ; Witwer, ; Zempleni, ; Zempleni et al., ; Zempleni, Sukreet, Zhou, Wu, & Mutai, ). Overall, the interest for milk microRNAs’ impact on health and disease is steadily increasing over the years.…”

“…The second major research avenue is about the potential bioactivity of milk microRNAs in newborns and adult consumers (Cui et al., ; Melnik & Schmitz, ; Melnik, John, Carrera‐Bastos, & Schmitz, ; Wang et al., ; Zempleni et al., , ). Their presence in large numbers (Weber et al., ) and the conservation of microRNAs and their mRNA targets between species (Friedman, Farh, Burge, & Bartel, ; Lee, Risom, & Strauss, ; van Herwijnen et al., ) has led some to postulate their bioactivity after ingestion.…”

“…To be functional after ingestion (that is, bioactive), milk microRNAs need to be orally bioacessible and systemically bioavailable (Benmoussa et al., ; Cardoso, Afonso, Lourenço, Costa, & Nunes, ; Lyng et al., ; Ting et al., ; Tome‐Carneiro et al., ; Wang et al., ).…”

“…For milk microRNAs, bioaccessibility is considered as “the quantity of a compound that is released from the milk matrix in the gastrointestinal tract, becoming available for absorption, including digestive transformations into material ready for assimilation” (Benmoussa et al., ; Cardoso et al., ; Lyng et al., ; Ting et al., ; Tome‐Carneiro et al., ; Wang et al., ). It is sometimes referred to as “survivability” to processing and digestion (Melnik & Schmitz, ).…”