Alpha-lactalbumin in human milk alters the proteolytic degradation of soluble CD14 by forming a complex

Exploring interplay between bovine milk-derived α-lactalbumin, pathogenic bacteria, and bacteriophages at the molecular interface of inflammation

There is so far no available data about how the additive, synergistic, or antagonistic effects of the combined form of alpha-lactalbumin (α-La) and bacteriophages might modulate the cellular milieu of the host-pathogen interface. A co-culture of colonocytes and hepatocytes was stimulated with Pseudomonas aeruginosa PAO1 in the presence of KPP22 phage and incubated for 6 hours in medium alone or medium supplemented with bovine milk-origin α-La. The combination of KPP22 phage and α-La significantly inhibited P.a PAO1-elicited secretion of IL-1β, IL-6, and ICAM-1, which are the mediators and enzymes associated with the inflammatory response to an infectious-inflamed milieu. Cell viability was higher in the P.a PAO1+ KPP22 phage group compared to the P.a PAO1alone group. KPP22 phage and α-La, either alone or in combination, rescued P.a PAO1-induced aberrant PGE1/PGE2 production ratios. The convergence of ingested α-La and phages mitigates pro-inflammatory mediators. α-La leads to an increased sensitivity of opportunistic pathogenic bacteria to phages. Structural, functional, or immunological similarities between ingested α-La and phages play an important role in the mitigation of infection-driven pathobiological processes.

Heat Stress Increases Mammary Epithelial Cells and Reduces Viable Immune Cells in Milk of Dairy Cows

Somatic cells normally found in milk are generally either immune cells such as lymphocytes, monocytes and granulocytes, or mammary epithelial cells. The number and composition of somatic cells in milk can be influenced by a variety of factors, including infection and temperature-humidity index. The objective of this study was to determine the specific effects of heat stress on the cellular composition of the somatic cell population in milk. We used flow cytometry to ascertain the concentration and viability of mammary epithelial cells, T cells, monocyte/macrophage, and granulocytes in milk from cows maintained under heat stressed conditions compared to thermoneutral conditions. We found a significant 10% increase in the natural log concentration of epithelial cells in the milk of heat stressed cows compared to thermoneutral cows (9.3 vs. 8.4 ln(cells/mL, p = 0.02)). We also found a 12% decrease in the log concentration of live CD45+ cells (p = 0.04), and a 17% decrease in the log concentration of live CD45+ granulocytes (p = 0.04). No changes were found in CD3+CD45+ cells or CD14+CD45+ cells, however, we noted an unusual population of CD14+CD45- cells that showed significant increases of 10% (p = 0.03) and 12% (p = 0.01) in the log concentration of total and dead cells, respectively, under heat stressed conditions. These results suggest that heat stress influences the relative populations and viability of some somatic cells populations in milk. Increased losses of secretory epithelial cells into milk could have implications for milk production, and fewer viable immune cells could negatively impact the immunocompetence of dairy cows under heat stress.

Human Breast Milk Enhances Intestinal Mucosal Barrier Function and Innate Immunity in a Healthy Pediatric Human Enteroid Model

Breastfeeding has been associated with long lasting health benefits. Nutrients and bioactive components of human breast milk promote cell growth, immune development, and shield the infant gut from insults and microbial threats. The molecular and cellular events involved in these processes are ill defined. We have established human pediatric enteroids and interrogated maternal milk's impact on epithelial cell maturation and function in comparison with commercial infant formula. Colostrum applied apically to pediatric enteroid monolayers reduced ion permeability, stimulated epithelial cell differentiation, and enhanced tight junction function by upregulating occludin. Breast milk heightened the production of antimicrobial peptide α-defensin 5 by goblet and Paneth cells, and modulated cytokine production, which abolished apical release of pro-inflammatory GM-CSF. These attributes were not found in commercial infant formula. Epithelial cells exposed to breast milk elevated apical and intracellular pIgR and enabled maternal IgA translocation. Proteomic data revealed a breast milk-induced molecular pattern associated with tissue remodeling and homeostasis. Using a novel ex vivo pediatric enteroid model, we have identified distinct cellular and molecular events involved in human milk-mediated improvement of human intestinal physiology and immunity.

Soluble CD14 in Breast Milk and Its Relation to Atopic Manifestations in Early Infancy

Soluble CD14 (sCD14) is one of the immunomodulatory factors in breast milk (BM). Although it may be involved in the prevention of atopic symptoms and sensitization to both food and inhalant allergens, conflicting evidence exists concerning its protective effects. In this study, we investigated the relationship between sCD14 in colostrum and 1-month BM, and the development of atopic dermatitis (AD) and sensitization to food and aeroallergens at 9 months of age in infants who were exclusively or almost exclusively breastfed up to 4 months of age. BM samples were collected from lactating mothers who participated in a 2 × 2 factorial, randomized, nontreatment controlled trial study set in Tokyo, which looked at the efficacy of emollients and synbiotics in preventing AD and food allergy in children during the first year of life. A total of 258 colostrum samples and 269 1-month BM samples were analyzed. We found that one-month BM sCD14 levels in the AD group were significantly lower than in the non-AD group. Levels of sCD14 in 1-month BM were not related to allergen sensitization in the overall analysis, but egg white sensitization correlated inversely with 1-month BM sCD14 in infants without AD. The results suggest that sCD14 in BM may be involved in atopic manifestations in early infancy.

Targeting Human α-Lactalbumin Gene Insertion into the Goat β-Lactoglobulin Locus by TALEN-Mediated Homologous Recombination

Special value of goat milk in human nutrition and well being is associated with medical problems of food allergies which are caused by milk proteins such as β-lactoglobulin (BLG). Here, we employed transcription activator-like effector nuclease (TALEN)-assisted homologous recombination in goat fibroblasts to introduce human α-lactalbumin (hLA) genes into goat BLG locus. TALEN-mediated targeting enabled isolation of colonies with mono- and bi-allelic transgene integration in up to 10.1% and 1.1%, respectively, after selection. Specifically, BLG mRNA levels were gradually decreasing in both mo- and bi-allelic goat mammary epithelial cells (GMECs) while hLA demonstrated expression in GMECs in vitro. Gene-targeted fibroblast cells were efficiently used in somatic cell nuclear transfer, resulting in production of hLA knock-in goats directing down-regulated BLG expression and abundant hLA secretion in animal milk. Our findings provide valuable background for animal milk optimization and expedited development for agriculture and biomedicine.

RNA-Seq reveals 10 novel promising candidate genes affecting milk protein concentration in the Chinese Holstein population

Paired-end RNA sequencing (RNA-Seq) was used to explore the bovine transcriptome from the mammary tissue of 12 Chinese Holstein cows with 6 extremely high and 6 low phenotypic values for milk protein percentage. We defined the differentially expressed transcripts between the two comparison groups, extremely high and low milk protein percentage during the peak lactation (HP vs LP) and during the non-lactating period (HD vs LD), respectively. Within the differentially expressed genes (DEGs), we detected 157 at peak lactation and 497 in the non-lactating period with a highly significant correlation with milk protein concentration. Integrated interpretation of differential gene expression indicated that SERPINA1, CLU, CNTFR, ERBB2, NEDD4L, ANG, GALE, HSPA8, LPAR6 and CD14 are the most promising candidate genes affecting milk protein concentration. Similarly, LTF, FCGR3A, MEGF10, RRM2 and UBE2C are the most promising candidates that in the non-lactating period could help the mammary tissue prevent issues with inflammation and udder disorders. Putative genes will be valuable resources for designing better breeding strategies to optimize the content of milk protein and also to provide new insights into regulation of lactogenesis.

Ingested soluble CD14 from milk is transferred intact into the blood of newborn rats

BACKGROUND

Milk acts as an edible immune system that is transferred from mother to newborn. Soluble Cluster of Differentiation 14 (sCD14) is a protein found in significant quantities in human milk (~8-29 µg/ml). At a 10-fold lower concentration in the blood (~3 µg/ml), the most notable role of sCD14 is to sequester lipopolysaccharides of Gram-negative bacteria from immune cells.

METHODS

To explore the pharmacodynamics of this milk protein and its biological fate, the biodistribution of radiolabeled sCD14 ((14)C, (125)I) was monitored in 10-d-old rat pups.

RESULTS

Up to 3.4 ± 2.2% of the radiolabeled sCD14 administered was observed, intact, in the pup blood for up to 8 h post-ingestion. Additionally, 30.3 ± 13.0% of the radiolabeled sCD14 administered was observed degraded in the stomach at 8 h post-ingestion. A reservoir of intact, administered sCD14 (3.2 ± 0.3%), however, remained in the stomach at 8 h post-ingestion. Intact sCD14 was observed in the small intestine at 5.5 ± 1.6% of the dose fed at 8 h post-ingestion.

CONCLUSION

The presence of intact sCD14 in the blood and the gastrointestinal tract of newborns post-ingestion has implications in the development of allergies, obesity, and other inflammation-related pathogeneses later in life.

Human milk metagenome: a functional capacity analysis

BACKGROUND

Human milk contains a diverse population of bacteria that likely influences colonization of the infant gastrointestinal tract. Recent studies, however, have been limited to characterization of this microbial community by 16S rRNA analysis. In the present study, a metagenomic approach using Illumina sequencing of a pooled milk sample (ten donors) was employed to determine the genera of bacteria and the types of bacterial open reading frames in human milk that may influence bacterial establishment and stability in this primal food matrix. The human milk metagenome was also compared to that of breast-fed and formula-fed infants' feces (n = 5, each) and mothers' feces (n = 3) at the phylum level and at a functional level using open reading frame abundance. Additionally, immune-modulatory bacterial-DNA motifs were also searched for within human milk.

RESULTS

The bacterial community in human milk contained over 360 prokaryotic genera, with sequences aligning predominantly to the phyla of Proteobacteria (65%) and Firmicutes (34%), and the genera of Pseudomonas (61.1%), Staphylococcus (33.4%) and Streptococcus (0.5%). From assembled human milk-derived contigs, 30,128 open reading frames were annotated and assigned to functional categories. When compared to the metagenome of infants' and mothers' feces, the human milk metagenome was less diverse at the phylum level, and contained more open reading frames associated with nitrogen metabolism, membrane transport and stress response (P < 0.05). The human milk metagenome also contained a similar occurrence of immune-modulatory DNA motifs to that of infants' and mothers' fecal metagenomes.

CONCLUSIONS

Our results further expand the complexity of the human milk metagenome and enforce the benefits of human milk ingestion on the microbial colonization of the infant gut and immunity. Discovery of immune-modulatory motifs in the metagenome of human milk indicates more exhaustive analyses of the functionality of the human milk metagenome are warranted.

An α-lactalbumin-enriched and symbiotic-supplemented v. a standard infant formula: a multicentre, double-blind, randomised trial

The aim of the present study was to evaluate the safety, tolerance and preventive effect on atopic dermatitis of an experimental α-lactalbumin-enriched and symbiotic-supplemented infant formula. A total of ninety-seven non-breastfed term neonates were enrolled into a double-blind, multicentre, randomised controlled trial in which they received experimental (n 48) or standard formula (n 49) for 6 months. The primary outcome was weight at 6 months of age. Secondary outcomes were gastrointestinal tolerance and manifestation of atopic dermatitis. Faecal secretory IgA (SIgA) concentration and microbiota composition of forty-three infants were analysed at 1 and 6 months. Growth was similar in both groups. At 1 month, compared to those in the control group, infants in the experimental group exhibited less crying or agitation, and more quiet behaviour (P=0·03). At 6 months, atopic dermatitis was less frequently observed in the experimental group (P<0·05). Decrease of faecal SIgA concentration between 1 and 6 months was mainly observed in the control group. This decrease was significantly associated with atopic dermatitis (P<0·014) and negatively correlated to the level of colonisation by bifidobacteria (P<0·005). In conclusion, compared to the control formula, the experimental formula guaranteed a similar growth, was better tolerated at 1 month and had a protective effect against the development of atopic dermatitis.

(14)C radiolabeling of proteins to monitor biodistribution of ingested proteins

The economical preparation of microgram quantities of (14)C-labeled proteins by in vacuo methylation with methyl iodide is described. The (14)C radiolabeling was achieved by the covalent attachment of [(14)C]methyl groups onto amino and imidazole groups by reaction in vacuo with [(14)C]methyl iodide. The method was tested by investigating the biodistribution of (14)C in rats that were fed (14)C-labeled human soluble cluster of differentiation 14 (CD14) protein, a receptor for bacterial lipopolysaccharide. Two other control proteins, bovine serum albumin (BSA) and casein, were also labeled with (14)C and used for comparative analysis to determine the following: (i) the efficacy and cost efficiency of the in vacuo radiolabeling procedure and (ii) the extent of incorporation of the (14)C label into the organs of orogastrically fed 10-day-old Sprague-Dawley rats. [(14)C]BSA, [(14)C]casein, and [(14)C]CD14 were individually prepared with specific radioactivities of 34,400, 18,800, and 163,000 disintegrations per minute (dpm)/microg, respectively. It was found that the accumulation of (14)C label in the organs of [(14)C]CD14-fed rats, most notably the persistence of (14)C in the stomach 480 min postgavage, was temporally and spatially distinct from [(14)C]BSA and [(14)C]casein-fed rats.