Apical-to-basolateral transepithelial transport of cow's milk caseins by intestinal Caco-2 cell monolayers: MS-based quantitation of cellularly degraded α- and β-casein fragments

Assembly of neuron- and radial glial-cell-derived extracellular matrix molecules promotes radial migration of developing cortical neurons

Radial neuronal migration is a key neurodevelopmental event for proper cortical laminar organization. The multipolar-to-bipolar transition, a critical step in establishing neuronal polarity during radial migration, occurs in the subplate/intermediate zone (SP/IZ), a distinct region of the embryonic cerebral cortex. It has been known that the extracellular matrix (ECM) molecules are enriched in the SP/IZ. However, the molecular constitution and functions of the ECM formed in this region remain poorly understood. Here, we identified neurocan (NCAN) as a major chondroitin sulfate proteoglycan in the mouse SP/IZ. NCAN binds to both radial glial-cell-derived tenascin-C (TNC) and hyaluronan (HA), a large linear polysaccharide, forming a ternary complex of NCAN, TNC, and HA in the SP/IZ. Developing cortical neurons make contact with the ternary complex during migration. The enzymatic or genetic disruption of the ternary complex impairs radial migration by suppressing the multipolar-to-bipolar transition. Furthermore, both TNC and NCAN promoted the morphological maturation of cortical neurons in vitro. The present results provide evidence for the cooperative role of neuron- and radial glial-cell-derived ECM molecules in cortical development.

Allergen Content and Protease Activity in Milk Feeds from Mothers of Preterm Infants

Rationale: There is little information regarding the allergen content of milk feeds in the preterm population. Previous studies have not performed a broad analysis of the allergenic peptide content and protease activity of milk feeds in this population. Methods: To evaluate feasibility, we initially performed mass spectrometry on 4 human milk (HM) samples (2 term and 2 preterm) from the Mommy's Milk Human Milk Biorepository (HMB) and analyzed the results against the University of Nebraska FASTA database and UniProt for a total of 2,211 protein sequences. We then further analyzed five samples from the Microbiome, Atopy, and Prematurity (MAP) study including peptidomic and protease activity analysis. Results: Each HMB sample had between 806 and 1,007 proteins, with 37-44 nonhuman proteins/sample encompassing 26 plant and animal species. In the preterm MAP samples, 784 digested nonhuman proteins were identified, 30 were nonbovine in origin. Proteins from 23 different species including aeroallergens, food, and contact allergens were identified. Protease activity was highest in HM samples without human milk fortifier and lowest in preterm formula. Conclusions: These findings represent the first preterm milk feed mass spectrometry and protease analysis with identification of known allergenic proteins to food, contact, and aeroallergens. These results raise questions of whether the composition of milk feeds in the neonatal intensive care unit impact the development of atopic disease in the preterm population and whether the complex interaction between allergens, proteases, and other HM components can serve to induce sensitization or tolerance to allergens in infants. Clinical Trial Registration Number: NCT04835935.

Novel Angiotensin-I Converting Enzyme Inhibitory Peptides Isolated From Rice Wine Lees: Purification, Characterization, and Structure-Activity Relationship

The bioactive peptides that can inhibit angiotensin-I converting enzyme (ACE, EC. 3. 4.15.1) are considered as possible cures of hypertension. Food-derived angiotensin-I converting enzyme inhibitory (ACEi) peptides have gained more attention because of their reduced side effects. In this study, we reported the method for purifying ACEi peptides from the lees of traditional Chinese rice wine and evaluated the product's biochemical properties. After three steps of reversed-phase high-performance liquid chromatography (RP-HPLC), for the first time, we isolated, purified, and identified two novel peptides: LIIPQH and LIIPEH, both of which showed strong ACEi activity (IC₅₀-values of 120.10 ± 9.31 and 60.49±5.78 μg/ml, respectively). They were further categorized as mixed-type ACE inhibitors and were stable against both ACE and gastrointestinal enzymes during in vitro digestion. Together, these results suggest that the rice wine lees that produced as a by-product during rice wine production can be utilized in various fields related to functional foods and antihypertensive medicine.

Provider recommendations and maternal practices when providing breast milk to children with immunoglobulin E-mediated food allergy

BACKGROUND

There is limited research investigating maternal dietary practices and health care provider recommendations when providing breast milk (BM) to children with immunoglobulin (Ig) E-mediated food allergy.

OBJECTIVE

To explore health care provider recommendations and maternal practices when providing BM to children with IgE-mediated food allergy and to assess for possible IgE-mediated reactions to BM while the mother consumed the food to which her child has allergy.

METHODS

A web-based survey was distributed to breastfeeding (BF) mothers of children with IgE-mediated food allergies. Reported reactions to BM were scored by an allergist, provided only with the details of the possible reaction and not the suspect allergen or route of exposure, as to the likelihood that the reaction was IgE mediated.

RESULTS

A total of 133 mothers completed the survey. After food allergy diagnosis, 47.4% (n = 63) of the mothers reported that they were advised by their health care provider to continue BF without dietary restriction, 17.3% (n = 23) were advised to avoid eating the food(s) their child has allergy to while BF, and in 28.6% (n = 38), this concern was not addressed. A few of the mothers (12%, 16/133) reported that their child experienced an allergic reaction to BM. An allergist evaluated most of these reactions (75%, 12/16) as not likely IgE mediated.

CONCLUSION

This study exposed inconsistent recommendations for mothers providing BM to children with IgE-mediated food allergies. Most mothers were able to consume the food their child has allergy to without adverse sequelae. Standardized, evidence-based recommendations would enhance the well-being of these mother-infant dyads.

Evaluation of cross-reactivity between casein components using inhibition assay and in silico analysis

BACKGROUND

We previously reported that the specific IgE levels to αs1-casein (CN) and β-CN in patients with cow's milk allergy decreased with similar dynamics during oral immunotherapy. Therefore, we hypothesized that αs1- and β-CN have strong cross-reactivity among CN components, despite the low similarity in the full-length amino acid sequences.

METHODS

The αs1-, β-, and κ-CN were purified from commercial cow's milk. We recruited 39 patients with cow's milk allergy, and the serum IgE levels for each CN component were measured by enzyme-linked immunosorbent assay (ELISA). Cross-reactivity between CN components was investigated by competitive ELISA against αs1-CN. Sequence homology between CN components at the peptide level was calculated using in silico analysis and quantified by the property distance (PD) value.

RESULTS

The αs1-CN-specific IgE levels exhibited a strong positive correlation with the β-CN-specific IgE (r = 0.945, P < .001). Complete competition was observed by β-CN against αs1-CN, suggesting the presence of common epitopes between them. In silico analysis detected 24 peptide sets with PD values lower than 10 between αs1- and β-CN, and 14 sets between αs1- and κ-CN. The amino acid sequences of αs1-CN (E61-E70) and β-CN (I12-E21) that showed the lowest PD value (5.30) were present in the characteristic sequence known as casein phosphopeptide (CPP).

CONCLUSION

We detected strong cross-reactivity between CN components. Furthermore, we found highly homologous sequences in the CPP region, which contains a core sequence of "SSSEE" with phosphorylated serine residues.

Hyaluronan degradation and release of a hyaluronan-aggrecan complex from perineuronal nets in the aged mouse brain

BACKGROUND

Perineuronal nets (PNNs) are insoluble aggregates of extracellular matrix molecules in the brain that consist of hyaluronan (HA) and chondroitin sulfate proteoglycans (CSPGs). PNNs promote the acquisition and storage of memories by stabilizing the formation of synapses in the adult brain. Although the deterioration of PNNs has been suggested to contribute to the age-dependent decline in brain function, the molecular mechanisms underlying age-related changes in PNNs remain unclear.

METHODS

The amount and solubility of PNN components were investigated by sequential extraction followed by a disaccharide analysis and immunoblotting. We examined the interaction between HA and aggrecan, a major HA-binding CSPG, by combining mass spectrometry and pull-down assays.

RESULTS

The solubility and amount of HA increased in the brain with age. Among several CSPGs, the solubility of aggrecan was selectively elevated during aging. In contrast to alternations in biochemical properties, the expression of PNN components at the transcript level was not markedly changed by aging. The increased solubility of aggrecan was not due to the loss of HA-binding properties. Our results indicated that the degradation of high-molecular-mass HA induced the release of the HA-aggrecan complex from PNNs in the aged brain.

CONCLUSION

The present study revealed a novel mechanism underlying the age-related deterioration of PNNs in the brain.

Predominant secretion of cellobiohydrolases and endo-β-1,4-glucanases in nutrient-limited medium by Aspergillus spp. isolated from subtropical field

Biological degradation of cellulose from dead plants in nature and plant biomass from agricultural and food-industry waste is important for sustainable carbon recirculation. This study aimed at searching diverse cellulose-degrading systems of wild filamentous fungi and obtaining fungal lines useful for cellooligosaccharide production from agro-industrial wastes. Fungal lines with cellulolytic activity were screened and isolated from stacked rice straw and soil in subtropical fields. Among 13 isolated lines, in liquid culture with a nutrition-limited cellulose-containing medium, four lines of Aspergillus spp. secreted 50–60 kDa proteins as markedly dominant components and gave clear activity bands of possible endo-β-1,4-glucanase in zymography. Mass spectroscopy (MS) analysis of the dominant components identified three endo-β-1,4-glucanases (GH5, GH7 and GH12) and two cellobiohydrolases (GH6 and GH7). Cellulose degradation by the secreted proteins was analysed by LC-MS-based measurement of derivatized reducing sugars. The enzymes from the four Aspergillus spp. produced cellobiose from crystalline cellulose and cellotriose at a low level compared with cellobiose. Moreover, though smaller than that from crystalline cellulose, the enzymes of two representative lines degraded powdered rice straw and produced cellobiose. These fungal lines and enzymes would be effective for production of cellooligosaccharides as cellulose degradation-intermediates with added value other than glucose.

Maternal Allergy and the Presence of Nonhuman Proteinaceous Molecules in Human Milk

Human milk contains proteins and/or protein fragments that originate from nonhuman organisms. These proteinaceous molecules, of which the secretion might be related to the mother's allergy status, could be involved in the development of the immune system of the infant. This may lead, for example, to sensitization or the induction of allergen-specific tolerance. The aim of this study was to investigate the relation between maternal allergy and the levels of nonhuman proteinaceous molecules in their milk. In this study, we analysed trypsin-digested human milk serum proteins of 10 allergic mothers and 10 nonallergic mothers. A search was carried out to identify peptide sequences originating from bovine or other allergenic proteins. Several methods were applied to confirm the identification of these sequences, and the differences between both groups were investigated. Out of the 78 identified nonhuman peptide sequences, 62 sequences matched Bos taurus proteins. Eight peptide sequences of bovine β -lactoglobulin had significantly higher levels in milk from allergic mothers than in milk from nonallergic mothers. Dietary bovine β -lactoglobulin may be absorbed through the intestinal barrier and secreted into human milk. This seems to be significantly higher in allergic mothers and might have consequences for the development of the immune system of their breastfed infant.

Discovery and Quantification of Nonhuman Proteins in Human Milk

The question whether and which nonhuman peptides or proteins are present in human milk was raised many decades ago. However, due to cross-reactivity or nonspecific antibody recognition, the accuracy of detection by immunochemical methods has been a concern. Additionally, the relative low-abundance of nonhuman peptides/proteins in the complex milk sample makes them a challenging target to detect. Here, by deep proteome profiling, we detected several nonhuman peptides, which could be grouped as nonhuman proteins. We next estimated their concentration in human milk by combining data-dependent shotgun proteomics and parallel reaction monitoring. First, we fractionated human milk at the protein level and were able to detect 1577 human proteins. Additionally, we identified 109 nonhuman peptides, of which 71 were grouped into 36 nonhuman proteins. In the next step, we targeted 37 nonhuman peptides and nine of them could be repeatedly quantified in human milk samples. Peptides/proteins originating from bovine milk products were the dominant nonhuman proteins observed, notably bovine caseins (α-S1-, α-S2-, β-, κ-caseins) and β-lactoglobulin. The method we present here can be expanded to investigate more about nonhuman peptides and proteins in human milk and give a better understanding of how human milk plays a role in allergy prevention.