Pasteurization of human milk affects the miRNA cargo of EVs decreasing its immunomodulatory activity

In this report, we evaluated the effect of the pasteurization (P) process of mother’s own milk (MOM) on the miRNA content of extracellular vesicles (EVs) and its impact on innate immune responses. Differences in size or particle number were not observed upon pasteurization of MOM (PMOM). However, significant differences were observed in the EV membrane marker CD63 and miRNA profiles. miRNA sequencing identified 33 differentially enriched miRNAs between MOM(EV) and PMOM(EV). These changes correlated with significant decreases in the ability of PMOM(EV) to modulate IL-8 secretion in intestinal Caco2 cells where only MOM(EV) were able to decrease IL-8 secretion in presence of TNFα. While EVs from MOM(EV) and PMOM(EV) were both able to induce a tolerogenic M2-like phenotype in THP-1 macrophages, a significant decrease in the transcript levels of IL-10 and RNA sensing genes was observed with PMOM(EV). Together, our data indicates that pasteurization of MOM impacts the integrity and functionality of MOM(EV), decreasing its EVs-mediated immunomodulatory activity. This data provides biomarkers that may be utilized during the optimization of milk processing to preserve its bioactivity.