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Conference

miRNA in human milk: a state of the art.

Clair-Yves BOQUIEN

INRA – Nantes University, CRNH-West, Nantes University Hospital, EMBA, Nantes (FRANCE)

MicroRNAs (miRNAs) are endogenous non-coding 22 nucleotides rnas that can play important regulatory roles in animals and plants by inhibiting gene expression at a post-transcriptional level. The number of human protein-coding genes that are considered to be targets of miRNAs is estimated to be 45,000 1.

MiRNAs have been isolated in high quantity from human milk. Skim milk has the lowest miRNA content amongst the three human milk fractions (cells, fat and skim milk). The number of unique miRNA identified at high abundance is variable (i.e.288 2) but they are many more with miRNA at low abundance (602 3 to 898 2). The majority of the differentially expressed microRNAs are implicated in innate immunity.

The concept of miRNA regulation has led to the question of whether mirna from human milk can regulate gene expression in infant and participate so to the “communication” between mother and her breastfed infant. Evidence is now accumulating that miRNAs are protected against degradation by being packaged in lipid vesicles or by being associated with protein or lipoprotein complexes. Milk miRNAs likely survive in infant gut. However how mother milk miRNAs can traverse the intestinal barrier and exert a regulatory function on infant gene expression is still debated.

References:

1. friedman rC, kk-H farh, burge Cb, bartel Dp. Most mammalian mrnas are conserved targets of micrornas. genome res 2009; 19: 92–105.

2. liao Y, Du X, li J, et al. Human milk exosomes and their micrornas survive digestion in vitro and are taken up by human intestinal cells. Mol nutr food res 2017 doi: 10.1002/mnfr.201700082[published online first: epub Date]|.

3. Zhou Q, li M, Wang X, et al. immune-related micrornas are abundant in breast milk exosomes. international journal of biological sciences 2012;8(1):118-23

Poster

In vitro lipolysis kinetics of human milks is dependent from fat globule structure

 C. Denis 1, C. Boquien 3, O. Menard 1, M. Croyal 2, J. Ossemond 2, D. Dupont 1, A. Deglaire 1

1 Agrocampus Ouest STLO, INRA, Rennes, France

2 INRA PhAN, Université de Nantes, CRNH Ouest, IMAD, DHU2020, Nantes, France

3 INRA PhAN, Université de Nantes, CRNH Ouest, IMAD, DHU2020, Nantes, France; EMBA, European Milk Bank Association, Milano, Italy

Human milk is a biological fluid suitable for newborn’s needs, which lipid content in the milk fat globules is variable and highly dependent on mother diet. the aim of this study was to link milk fat globule structure and fatty acid composition of their triglycerides with kinetics of lipolysis, while performing in vitro static digestion simulating what is happening in newborn gastro-intestinal tract. twelve human milks (1 month of lactation from mothers of term babies) from three european countries (norway, Spain, france) were classified in 3 groups by laser light scattering, according to the surface specific area of fat globules, and were characterized on their triglyceride and total fatty acid profiles.

While performing in vitro static digestion, follow-up of the particle size evolution (by laser light scattering) and of the lipolysis degree (by thin layer chromatography and densitometry and by fatty acid quantification through gas chromatography) was done in order to compare the three defined groups of human milk. there was less lipolysis for the low specific surface area group. there was also an intermediate linear correlation between polyunsaturated fatty acid content and specific surface area of the milk fat globules (r=-0.6; p-value = 0.04; n=12). the final effect on fatty acid release and so on newborn growth and development is another scientific question that will need to be challenged.

authors acknowledge breastfeeding mothers from Palma de Majorca (Sp) (contact: Mr. Antoni GAYA), Oslo (NO) (contact: Mrs. Anne GROVSLIEN) and Rennes (fr) (contact: Dr. Amandine BELLANGER).

key words: Human milk, milk fat globule, fatty acid, specific surface area, triglyceride, in vitro static digestion, maternal diet.