Marie-Caroline Michalski

MicroRNAs (miRNAs) are small regulatory RNAs that regulate numerous biological processes and potentially impact human health. Despite their abundance in raw milk, little is known about their content in processed dairy products or how manufacturing affects their abundance and bioavailability. We characterized and compared the miRNA profiles of yogurt and cheese produced from the same raw milk from cows raised under agroecological or intensive systems, assessing compositional changes during processing, while accounting for farming system effects. High-throughput sequencing identified a total of 1,384 miRNAs, including 258 common to all matrices, forming a conserved milk-derived core. Processing into yogurt or cheese reduced milk-specific miRNAs while introducing microbial small RNAs from fermentation bacteria such as Lactococcus and Streptococcus thermophilus. Differential analysis revealed stable miRNomes across agroecological and intensive farming systems, but substantial processing-associated changes involving 29 and 353 miRNAs during cheese and yogurt production, respectively, and some miRNAs showed matrix-specific stability. These miRNAs were predicted to influence cell proliferation, metabolism, and protein-related pathways, suggesting shifts in the regulatory impact of milk-derived miRNAs in fermented dairy products. Overall, these findings underscore the dynamic nature of dairy miRNomes and the combined influence of processing and microbial activity in shaping miRNA composition.

Dairy products are major dietary sources of B vitamins. However, the impact of cow diet and dairy processing techniques on B vitamin concentrations remains unclear. This study investigated the effects of diet composition on B-vitamin content in raw milk and, in yogurt, and Cantal-type cheese produced therefrom. Forty Holstein and Montbéliarde-breed cows were assigned to either a grass-based agroecological system or a corn-based intensive system for 19 weeks. Vitamins B1, B2, B5, and B6 were quantified by liquid chromatography, and B9 and B12 by chemiluminescence. Milk from the agroecological system contained higher vitamin B2, and lower vitamin B5 concentrations than milk from the intensive system. This same pattern was also observed in cheese, but not in yogurt, showing impacts of technological processing. Adding probiotics into yogurts increased pyridoxal (B6) concentration. This study highlighted diet-related differences in B vitamin concentrations in raw milk, and these differences transferred to cheese but not to yogurt.

The health impact of dairy products is debated due to their high saturated fatty acid (SFA) content. Emerging evidence suggests that dairy products intake

Abetalipoproteinemia (FHBL-SD1) and chylomicron retention disease (FHBL-SD3) are rare recessive disorders of lipoprotein metabolism due to mutations in MTTP and SAR1B genes, respectively, which lead to defective chylomicron formation and secretion. This results in lipid and fat-soluble vitamin malabsorption, which induces severe neuro-ophthalmic complications. Currently, treatment combines a low-fat diet with high-dose vitamin A and E supplementation but still fails in normalizing serum vitamin E levels and providing complete ophthalmic protection. To explore these persistent complications, we developed two knock-out cell models of FHBL-SD1 and FHBL-SD3 using the CRISPR/Cas9 technique in Caco-2/TC7 cells. DNA sequencing, RNA quantification and Western blotting confirmed the introduction of mutations with protein knock-out in four clones associated with i) impaired lipid droplet formation and ii) defective triglyceride (−57.0 ± 2.6% to −83.9 ± 1.6%) and cholesterol (−35.3 ± 4.4% to −60.6 ± 3.5%) secretion. A significant decrease in α-tocopherol secretion was also observed in these clones (−41.5 ± 3.7% to −97.2 ± 2.8%), even with the pharmaceutical forms of vitamin E: tocopherol-acetate and tocofersolan (α-tocopheryl polyethylene glycol succinate 1000). MTTP silencing led to a more severe phenotype than SAR1B silencing, which is consistent with clinical observations. Our cellular models thus provide an efficient tool to experiment with therapeutic strategies and will allow progress in understanding the mechanisms involved in lipid metabolism.

This study evaluates the capacity of a bread enriched with fermentable dietary fibres to modulate the metabolism and nutrients handling between tissues, gut and peripheral, in a context of overfeeding. Net fluxes of glucose, lactate, urea, short chain fatty acids (SCFA), and amino acids were recorded in control and overfed female mini-pigs supplemented or not with fibre-enriched bread. SCFA in fecal water and gene expressions, but not protein levels or metabolic fluxes, were measured in muscle, adipose tissue, and intestine. Fibre supplementation increased the potential for fatty acid oxidation and mitochondrial activity in muscle (acox, ucp2, sdha and cpt1-m, p < 0.05) as well as main regulatory transcription factors of metabolic activity such as pparα, pgc-1α and nrf2. All these features were associated with a reduced muscle fibre cross sectional area, resembling to controls (i.e., lean phenotype). SCFA may be direct inducers of these cross-talk alterations, as their feces content (+52%, p = 0.05) was increased in fibre-supplemented mini-pigs. The SCFA effects could be mediated at the gut level by an increased production of incretins (increased gcg mRNA, p < 0.05) and an up-regulation of SCFA receptors (increased gpr41 mRNA, p < 0.01). Hence, consumption of supplemented bread with fermentable fibres can be an appropriate strategy to activate muscle energy catabolism and limit the establishment of an obese phenotype.

BACKGROUND: High circulating levels of ceramides (Cer) and sphingomyelins (SM) are associated with cardiometabolic diseases. The consumption of whole fat dairy products, naturally containing such polar lipids (PL), is associated with health benefits, but the impact on sphingolipidome remains unknown. METHODS: In a 4-week randomized controlled trial, 58 postmenopausal women daily consumed milk PL-enriched cream cheese (0, 3, or 5 g of milk PL). Postprandial metabolic explorations were performed before and after supplementation. Analyses included SM and Cer species in serum, chylomicrons, and feces. The ileal contents of 4 ileostomy patients were also explored after acute milk PL intake. RESULTS: Milk PL decreased serum atherogenic C24:1 Cer, C16:1 SM, and C18:1 SM species ( P _group < 0.05). Changes in serum C16+18 SM species were positively correlated with the reduction of cholesterol ( r = 0.706), LDL-C ( r = 0.666), and ApoB ( r = 0.705) ( P < 0.001). Milk PL decreased chylomicron content in total SM and C24:1 Cer ( P _group < 0.001), parallel to a marked increase in total Cer in feces ( P _group < 0.001). Milk PL modulated some specific SM and Cer species in both ileal efflux and feces, suggesting differential absorption and metabolization processes in the gut. CONCLUSION: Milk PL supplementation decreased atherogenic SM and Cer species associated with the improvement of cardiovascular risk markers. Our findings bring insights on sphingolipid metabolism in the gut, especially Cer, as signaling molecules potentially participating in the beneficial effects of milk PL. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02099032, NCT02146339. FUNDING: ANR-11-ALID-007-01; PHRCI-2014: VALOBAB, no. 14-007; CNIEL; GLN 2018-11-07; HCL (sponsor).

Scope: Synthetic emulsifiers have recently been shown to promote metabolic syndrome and considerably alter gut microbiota. Yet, data are lacking regarding the effects of natural emulsifiers, such as plant lecithins rich in essential α‐linolenic acid (ALA), on gut and metabolic health.Methods and Results: For 5 days, male Swiss mice are fed diets containing similar amounts of ALA and 0, 1, 3, or 10% rapeseed lecithin (RL) or 10% soy lecithin (SL). Following an overnight fast, they are force‐fed the same oil mixture and euthanized after 90 minutes. The consumption of lecithin significantly increased fecal levels of the Clostridium leptum group (p = 0.0004), regardless of origin or dose, without altering hepatic or intestinal expression of genes of lipid metabolism. 10%‐RL increased ALA abundance in plasma triacylglycerols at 90 minutes, reduced cecal bile acid hydrophobicity, and increased their sulfatation, as demonstrated by the increased hepatic RNA expression of Sult2a1 (p = 0.037) and cecal cholic acid‐7 sulfate (CA‐7S) concentration (p = 0.05) versus 0%‐lecithin.Conclusion: After only 5 days, nutritional doses of RL and SL modified gut bacteria in mice, by specifically increasing C. leptum group. RL also increased postprandial ALA abundance and induced beneficial modifications of the bile acid profile. ALA‐rich lecithins, especially RL, may then appear as promising natural emulsifiers.