Lipid profiling reveals the presence of unique lipid mediators in human milk from healthy and mastitic subjects.

Milk lipids are an important energy source for infants, but the composition of milk lipids has not yet been clarified in detail. In this study, we analyzed free fatty acids and their metabolites in milk from humans and cows. In comparison to cow milk, human milk showed a higher content of free fatty acids including polyunsaturated fatty acids, especially ω-3 fatty acids and their metabolites. Polyunsaturated fatty acids were enriched at an early period of lactation, while saturated fatty acids did not change significantly over the period. Moreover, human milk contained high levels of ω-3 fatty acid metabolites, particularly 18-hydroxyeicosapentaenoic acid, an eicosapentaenoic acid-derived metabolite with anti-inflammatory activity. In comparison with human normal milk, thromboxane B2 and protectin D1 levels were significantly elevated in milk from individuals with mastitis, suggesting that these lipid mediators could be potential biomarkers of obstructive mastitis. Overall, the unique lipid profile of human milk supports the efficacy of breast-feeding for supply of more nutritional and bioactive lipids in comparison to artificial or cow milk to infants, in whom digestive and absorptive functions are still immature.

Mucin-Derived O-Glycans Act as Endogenous Fiber and Sustain Mucosal Immune Homeostasis via Short-Chain Fatty Acid Production in Rat Cecum.

BACKGROUND: Intestinal mucins escape digestion and enter the large bowel where they are degraded by the microbiota. To what extent and how mucins impact large-bowel physiology remain unclear. OBJECTIVE: This study examined the large-bowel fermentation characteristics of mucins and mucin-derived O-glycan sugars and whether they affect gut immunity. METHODS: Mucin secretion from the terminal ileum was determined from feces of ileorectostomized male Wistar rats (age 6 wk) fed an AIN76-based control diet (CD) for 15 d (experiment 1). Normal male Wistar rats (age 6 wk; 4 wk for experiment 4) were fed CD ± porcine stomach mucin (PM) at 6 or 12 g/kg diet, equivalent to 1.5 and 3 times the daily mucin secretion, for 14 d (experiment 2); CD ± N-acetylglucosamine (GlcNAc), fucose, or N-acetylneuraminic acid at 10 g/kg diet for 14 d (experiment 3); or CD ± PM (15 g/kg diet) or GlcNAc (10 g/kg diet) for 29 d (experiment 4). SCFAs, microbial composition, and cecal O-glycan content were assessed. IgA+ plasma cells and regulatory T cells and inflammatory cytokine expression in the cecum were evaluated (experiment 4). RESULTS: Daily mucin secretion corresponded to 43.2 µmol of O-glycans. Cecal O-glycan contents were comparable between CD- and PM-fed rats. PM-fed rats harbored more mucin-degrading bacteria. Cecal concentrations of acetate (+37%) and n-butyrate (+73%) were higher in 12-g/kg PM diet-fed rats versus CD (P < 0.05). Among O-glycan sugars, only GlcNAc produced higher n-butyrate concentrations (+68%) versus CD (P < 0.05), with increased numbers of butyrate-producing bacteria. GlcNAc increased the abundance of IgA+ plasma cells (+29%) and regulatory T cells (+33%) versus CD, whereas PM increased IgA+ plasma cells (+25%) (all P < 0.05). GlcNAc and PM decreased expression of Tnfa (-30%, -40%) and Ifng (-30%, -70%) versus CD (all P < 0.05). CONCLUSIONS: Mucin-derived O-glycans act as endogenous fiber and maintain mucosal immune homeostasis via large-bowel SCFA production in rats.

Analysis of Gibbs monolayer adsorbed at the toluene/water interface by UV-visible partial internal reflection spectrometry.

Gibbs monolayers of lipophilic tetraphenylporphyrinatomanganese(III) and hydrophilic diacid of meso-tetrakis(4-sulfonatopheny)porphyrin adsorbed at the liquid-liquid interface have been analyzed by UV-visible external reflection (ER) and partial internal reflection (PIR) spectra measured at different angles of incidence. The angle-dependent ER and PIR spectra over the Brewster angles (thetaERB and thetaIRB) have readily been measured at the toluene/water interface. As preliminarily expected in our previous study, the present study has first proved that the reflection-absorbance of UV-visible PIR spectra quantitatively agrees with the theoretical calculations for the Gibbs monolayer over thetaIRB. In addition, it has also been proved that the absorbance of the PIR spectra is greatly enhanced in comparison to that of the ATR spectra. The enhancement is caused by an optical effect in the monolayer sandwiched between two phases of toluene and water that have different but refractive indices close to each other. This optical enhancement requires an optically perfect contact between the phases, which is difficult to prepare for a solid-solid contact. At the liquid/liquid interface, however, an ideal optical contact is easily realized, which makes the enhancement as much as the theoretical expectation. The PIR spectrometry will be recognized to be a new high-sensitive analytical tool to study Gibbs monolayer at the liquid/liquid interface.