Cow's milk allergens

Recent advances in selective allergies to mammalian milk proteins not associated with Cow's Milk Proteins Allergy

Cow's milk proteins allergy (CMA) is an atypical immune system response to cow's milk and dairy products. It's one of the most common food allergies in children affecting 8% of the total pediatric population pediatric population. This comprehensive review examines recent studies in CMA, especially regarding mammalian milk allergies such as goat's, sheep's, buffalo's, camel's, mare's and donkey's milk allergies in order to increase awareness of these selective allergies and to reduce allergy risks for those who have them. The consumption of other mammalian milk types is not recommended because of the significant homology between milk proteins from cow, sheep, goat and buffalo resulting in clinical cross-reactivity. However, camel's, mare's or donkey's milk may be tolerated by some allergic patients. Selective mammalian milk allergies are unusual and rare disorders characterized by severe symptoms including angio-oedema, urticaria, respiratory manifestations and anaphylaxis. Based on the reported allergic cases, cheese products including Ricotta, Romano, Pecorino and Mozzarella, are considered as the most common source of allergens especially in goat's, sheep's and buffalo's milk allergies, while the major allergens in donkey's and mare's milk seems to be whey proteins including lysozyme, α-lactalbumin and β-lactogloblin due to the low casein/whey proteins ratio in equine's milk.

Ultrasound-assisted glycation and the allergenicity of α-lactalbumin

BACKGROUND

Ultrasound-assisted glycation is a promising method for decreasing the allergenicity of α-lactalbumin (ALA). However, there is a lack of in vivo studies on the allergenicity of ultrasound-assisted glycated ALA. In this study, the effects of the ultrasound-assisted glycation of ALA on the allergenicity and intestinal microflora were characterized using a BALB/c mouse model.

RESULTS

Increased immunoglobulin -G/ immunoglobulin-E (IgG/IgE) and interleukin-4/6 (IL-4/6) secretions, and reduced interferon-γ (IFN-γ) secretions were found in the serum of ALA sensitized and challenged, mice in comparison with a control group. However, there was no significant difference between the mice fed with ultrasound-assisted glycated ALA and the control group. Mice that were sensitized and challenged with ALA showed disrupted intestinal microflora, manifesting in significantly decreased Firmicutes and significantly increased Proteobacteria. It was found that 100ALA-gal could maintain the intestinal microflora of mice in a normal state. Pearson's rank correlation showed that Proteobacteria and Spirochaetota were correlated positively with the IL-4/IL-6 level and were correlated negatively with the expression of IFN-γ. Proteobacteria were also significantly positively correlated with IL-6 and negatively correlated with IFN-γ (P < 0.05).

CONCLUSION

These results suggested that ultrasound-assisted glycation on ALA can maintain the intestinal microflora in a normal state thus balancing the proportion of Th1/Th2 to decrease allergic reaction. © 2022 Society of Chemical Industry.

Detection of β-lactoglobulin under different thermal-processing conditions by immunoassay based on nanobody and monoclonal antibody

The problems of inaccurate detection values of thermal-processed β-lactoglobulin (β-LG) content seriously affect the screening of allergens. A monoclonal antibody (mAb) against β-LG was successfully prepared and a highly sensitive sandwich ELISA (sELISA) was constructed with specific nanobody (Nb) as the capture antibody with detection limit of 0.24 ng/mL. Based on this sELISA, the ability of Nb and mAb to recognize β-LG and β-LG interacting with milk components was explored. Combined with protein structure analysis to elaborate the mechanism of shielding β-LG antigen epitopes during thermal-processing, thus enabling the differentiation between pasteurized and ultra-high temperature sterilized milk, the detection of milk content in milk-containing beverages, and the highly sensitive detection and analysis of β-LG allergens in dairy-free products. The method provides methodological support for identifying the quality of dairy products and reducing the risk of β-LG contamination in dairy-free products.

Favourable Interfacial Characteristics of A2 Milk Protein Monolayer

Shielding of the specific body organ using the biocompatible material helps preventing direct exposure of that part to the foreign entities responsible for infections. Here we show the potential of the A2 milk protein recovered from the milk of cow from Indian origin for possible prevention of the direct exposure to other foreign molecules. We measured the surface pressure of the monolayers of different types of protein samples using Langmuir isotherm experiments. The surface pressure measurements for the monolayer of four types of protein macromolecules have been carried out using the Wilhelmy plate micro pressure sensor. We studied the self-organization of different protein macromolecules and their monolayer compression characteristics. The electrochemical behaviour is studied using electrochemical impedance spectroscopy. We found the highest surface pressure for the monolayer of A2 protein. Further, it is also found that A2 protein exhibited the highest surface activity amongst the other proteins. This property can be effectively used for making the envelope of the A2 protein surrounding the targeted entity.

Review: Genetic and protein variants of milk caseins in goats

The milk casein genes in goats, are highly polymorphic genes with numerous synonymous and non-synonymous mutations. So far, 20 protein variants have been reported in goats for alpha-S1-casein, eight for beta-casein, 14 for alpha-S2-casein, and 24 for kappa-casein. This review provides a comprehensive overview on identified milk casein protein variants in goat and non-coding DNA sequence variants with some affecting the expression of the casein genes. The high frequency of some casein protein variants in different goat breeds and geographical regions might reflect specific breeding goals with respect to milk processing characteristics, properties for human nutrition and health, or adaptation to the environment. Because protein names, alongside the discovery of protein variants, go through a historical process, we linked old protein names with new ones that reveal more genetic variability. The haplotypes across the cluster of the four genetically linked casein genes are recommended as a valuable genetic tool for discrimination between breeds, managing genetic diversity within and between goat populations, and breeding strategies. The enormous variation in the casein proteins and genes is crucial for producing milk and dairy products with different properties for human health and nutrition, and for genetic improvement depending on local breeding goals.

Investigation on the Anaphylaxis and Anti-Digestive Stable Peptides Identification of Ultrasound-Treated α-Lactalbumin during In-Vitro Gastroduodenal Digestion

Our previous studies indicated that ultrasound treatment can increase the anaphylaxis of protein. However, investigation on the anaphylaxis changes of ultrasound-treated α-lactalbumin (ALA) during digestion is lacking. The anaphylaxis of ultrasound-treated ALA and its digesta was investigated. The anti-digestive stable peptides were identified by high-resolution mass spectrometry. Ultrasound induced the tertiary structure of ALA to unfold and increased its anaphylaxis. During digestion, the anaphylaxis of both gastric and gastroduodenal digesta was further increased. There are two reasons for this phenomenon. On the one hand, linear epitopes played an important role in affecting anaphylaxis compared with the conformational epitope, and some linear epitopes were still retained on the anti-digestive stable peptides produced after gastroduodenal digestion, resulting in increased anaphylaxis after digestion. On the other hand, the presence of intact ALA molecules after digestion still remained strong anaphylaxis. Compared with the digesta of untreated ALA, the digesta of ultrasound-treated ALA possessed higher anaphylaxis. The results indicated that ultrasound increased the anaphylaxis of ALA during digestion.

Effects of enzymatic hydrolysis on the allergenicity of natural cow milk based on a BALB/c mouse model

Cow milk allergy is one of the most prevalent food allergies worldwide, particularly in infants and children. To the best of our knowledge, minimal research exists concerning the antigenicity of cow milk (CM). This study was performed to evaluate the allergenicity of enzymatically hydrolyzed cow milk (HM) in a BALB/c mouse model. The mice were randomly divided into 5 groups (n = 12/group), which were sensitized with phosphate-buffered saline, CM, and HM (Alcalase-, or Protamex-, or Flavorzyme-treated cow milk; Novo Nordisk; AT, PT, FT, respectively), respectively, using cholera toxin as adjuvant on d 0, 7, 14, 21. On d 28, the test mice were orally challenged with phosphate-buffered saline, CM, and HM (AT, PT, or FT) alone. Anaphylactic symptoms were monitored in the mice. Antibody, cytokine, histamine, and mouse mast cell protease-1 (mMCP-1) levels were measured using enzyme-linked immunosorbent assays. In addition, the numbers of T helper (Th)1 and Th2 cells, as well as the proportions of CD4⁺CD25⁺Foxp3⁺ Treg cells, in mouse spleens were detected using flow cytometry. Statistical significance was determined by one-way ANOVA. The results revealed significant differences between CM- and HM-challenged mice. Among these, the clinical scores of HM-challenged mice (AT, 1.50; PT, 2.00; FT, 1.92) were lower than those of CM-challenged mice (positive control, 2.83), but body weight and temperature of HM-challenged mice were higher than those of CM-challenged mice. In addition, significant reductions of allergen-specific IgE, IgG, histamine, and mMCP-1 were showed in HM-challenged mice, especially for histamine, ranging from 171.42 ng/mL to 214.94 ng/mL. Remarkable reductions of IL-4, IL-5, and IL-13 levels, as well as elevations of interferon-γ and IL-10 levels in the spleens of HM-challenged mice were also detected. Moreover, the number of Th2 cells decreased in the HM-challenged mice, to 2.36% (AT), 1.79% (PT), and 4.03% (FT), respectively, whereas the numbers of Th1 cells (AT, 6.30%; PT, 6.70%; FT, 6.56%) and the proportions of CD4⁺CD25⁺Foxp3⁺Tregs (AT, 8.86%; PT, 9.21%; FT, 9.16%) increased significantly. Our findings indicate that exposure to HM was sufficient to induce a shift toward a Th1 response, thereby reducing potential allergenicity. Importantly, these results will lay a theoretical foundation for the development of hypoallergenic CM products.

Evaluation of antigenicity and nutritional properties of enzymatically hydrolyzed cow milk

While enzymatic hydrolysis is an effective method for lowering the antigenicity of cow milk (CM), research regarding the antigenicity and nutritional traits of CM hydrolysate is limited. Here, we evaluated the protein content, amino acid composition, sensory traits, color, flow behavior, and antigenicity of CM following enzymatic hydrolysis. The results showed that enzymatic hydrolysis increased the degree of hydrolysis, destroyed allergenic proteins, including casein, β-lactoglobulin, and ɑ-lactalbumin, and significantly increased the content of free amino acids and nutritional quality. In particular, the antigenicity of CM was significantly reduced from 44.05 to 86.55% (P < 0.5). Simultaneously, the taste, color, and flow behavior of CM were altered, the sweetness and richness intensity decreased significantly (P < 0.5), and astringency and bitterness were produced. A slightly darker and more yellow color was observed in CM hydrolysate. In addition, apparent viscosity decreased and shear stress significantly increased with increasing shear rate intensity. The results will provide a solid theoretical foundation for the development of high-quality hypoallergenic dairy products.

Differences in Regulatory Mechanisms Induced by β-Lactoglobulin and κ-Casein in Cow's Milk Allergy Mouse Model-In Vivo and Ex Vivo Studies

The presence of various proteins, including modified ones, in food which exhibit diverse immunogenic and sensitizing properties increases the difficulty of predicting host immune responses. Still, there is a lack of sufficiently reliable and comparable data and research models describing allergens in dietary matrices. The aim of the study was to estimate the immunomodulatory effects of β-lactoglobulin (β-lg) in comparison to those elicited by κ-casein (κ-CN), in vivo and ex vivo, using naïve splenocytes and a mouse sensitization model. Our results revealed that the humoral and cellular responses triggered by β-lg and κ-CN were of diverse magnitudes and showed different dynamics in the induction of control mechanisms. β-Lg turned out to be more immunogenic and induced a more dominant Th1 response than κ-CN, which triggered a significantly higher IgE response. For both proteins, CD4⁺ lymphocyte profiles correlated with CD4⁺CD25⁺ and CD4⁺CD25⁺Foxp3⁺ T cells induction and interleukin 10 secretion, but β-lg induced more CD4⁺CD25⁺Foxp3^- Tregs. Moreover, ex vivo studies showed the risk of interaction of immune responses to different milk proteins, which may exacerbate allergy, especially the one caused by β-lg. In conclusion, the applied model of in vivo and ex vivo exposure to β-lg and κ-CN showed significant differences in immunoreactivity of the tested proteins (κ-CN demonstrated stronger allergenic potential than β-lg), and may be useful for the estimation of allergenic potential of various food proteins, including those modified in technological processes.

A THP-1 Cell Line-Based Exploration of Immune Responses Toward Heat-Treated BLG

Allergen recognition and processing by antigen presenting cells is essential for the sensitization step of food allergy. Macrophages and dendritic cells are both phagocytic antigen presenting cells and play important roles in innate immune responses and signaling between the innate and adaptive immune system. To obtain a model system with a homogeneous genetic background, we derived macrophages and dendritic cells from THP-1 monocytes. The difference between macrophages and dendritic cells was clearly shown by differences in their transcription response (microarray) and protein expression levels. Their resemblance to primary cells was analyzed by comparison to properties as described in literature. The uptake of β-lactoglobulin after wet-heating (60°C in solution) by THP-1 derived macrophages was earlier reported to be significantly increased. To analyse the subsequent immune response, we incubated THP-1 derived macrophages and dendritic cells with native and differently processed β-lactoglobulin and determined the transcription and cytokine expression levels of the cells. A stronger transcriptional response was found in macrophages than in dendritic cells, while severely structurally modified β-lactoglobulin induced a more limited transcriptional response, especially when compared to native and limitedly modified β-lactoglobulin. These results show that processing is relevant for the transcriptional response toward β-lactoglobulin of innate immune cells.

Development of Immunohistochemical Methods for Casein Detection in Meat Products

To increase production efficiency of meat products, milk protein additives are often used. Despite a number of advantages, use of dairy ingredients involves a certain risk, namely the allergenic potential of milk proteins. A number of methods have been developed to detect milk-origin raw materials in foodstuffs, including immunological reference methods. This study presents newly developed immunohistochemical (IHC) methods for casein detection in meat products. Casein was successfully detected directly in meat products where sensitivity was determined at 1.21 and specificity at 0.28. The results obtained from the IHC were compared with the Enzyme-Linked Immuno Sorbent Assay (ELISA) and there was no statistically significant difference between the IHC and ELISA methods (p > 0.05). The correspondence between the methods was 72% in total. The highest correspondence was reached in frankfurters (90%), the lowest in canned pâté (44%).

Digestomics of Cow's Milk: Short Digestion-Resistant Peptides of Casein Form Functional Complexes by Aggregation

The aim of this study was to identify short digestion-resistant peptides (SDRPs) released by pepsin digestion of the whole cow’s milk and examine their IgE reactivity and allergenicity. Raw milk was subjected to simulated gastric digestion. SDRPs were fractionated from the digests and identified by MS. Milk SDRPs were evaluated for aggregability, propensity to compete for IgE binding with individual milk allergens, and ability to bind IgG4 from allergic and milk-tolerant individuals. The majority of milk SDRPs originated from caseins (97% of peptides) and overlapped with the known IgE epitopes of cow’s milk allergens. SDRPs competed with milk proteins for binding to human IgE and readily formed aggregates. The average peptide length was 10.6 ± 3.5 amino acids. The ability to provoke allergenic in vivo responses was confirmed by skin-prick testing (SPT) in five milk-allergic subjects. This was attributed to the peptide ability to aggregate into non-covalent complexes. SDRPs are able to induce response in SPT, but only in 50% of the sera SDRPs were able to inhibit IgG4 binding to caseins. Hence, SDRPs corresponding to the mainly continuous epitopes of milk proteins induce allergenic in vivo responses in milk-allergic subjects due to aggregation.

The effect of atmospheric cold plasma treatment on the antigenic properties of bovine milk casein and whey proteins

Casein, β-lactoglobulin and α-lactalbumin are major milk protein allergens. In the present study, the structural modifications and antigenic response of these bovine milk allergens as induced by non-thermal treatment by atmospheric cold plasma were investigated. Spark discharge (SD) and glow discharge (GD), as previously characterized cold plasma systems, were used for protein treatments. Casein, β-lactoglobulin and α-lactalbumin were analyzed before and after plasma treatment using SDS-PAGE, FTIR, UPLC-MS/MS and ELISA. SDS-PAGE results revealed a reduction in the casein and α-lactalbumin intensity bands after SD or GD treatments; however, the β-lactoglobulin intensity band remained unchanged. FTIR studies revealed alterations in protein secondary structure induced by plasma, particularly contents of β-sheet and β-turn. The UPLC-MS/MS results showed that the amino acid compositions decreased after plasma treatments. ELISA of casein and α-lactalbumin showed a decrease in antigenicity post plasma treatment, whereas ELISA of β-lactoglobulin showed an increase in antigenicity. The study indicates that atmospheric cold plasma can be tailored to mitigate the risk of bovine milk allergens in the dairy processing and ingredients sectors.

Natural ingredients in cosmetic products-A suggestion for a screening series for skin allergy

BACKGROUND

Naturally derived cosmetic product ingredients of both plant and animal origin are being included increasingly in product formulations in order to cater to consumer preferences. They may be an overlooked cause of reactions to cosmetic products in some patients with dermatitis.

OBJECTIVES

To identify naturally derived cosmetic product ingredients with allergenic potential (type I and type IV) and propose a cosmetic screening test series.

METHODS

The study was conducted in two steps. The first step was a market survey using a nonprofit application helping consumers avoid problematic substances in cosmetic products. The application contained 10 067 cosmetic products that were label checked for naturally derived cosmetic product ingredients. The second step was a literature search to examine how frequently the naturally derived ingredients were described and related to allergic reactions in cosmetics or other topically administered products.

RESULTS

We identified 121 different naturally derived cosmetic product ingredients that were included in at least 30 cosmetic products. In total, 22 ingredients were selected for a screening test series.

CONCLUSIONS

We propose a supplemental patch test and a prick test screening series with naturally derived cosmetic product ingredients for patients with skin reactions to cosmetic products, aiming to identify a cause in more patients than is currently possible.

Effect of ultrasonic-ionic liquid pretreatment on the hydrolysis degree and antigenicity of enzymatic hydrolysates from whey protein

With the aim to reduce the antigenicity of whey protein hydrolysate in milk, the pretreatment method of coupling ultrasonic and ionic liquid (US-IL) and further enzymatic treatments were studied. Papain and alcalase were found to be suitable for ultrasonic-ionic liquid pretreatment. After ultrasound-ionic liquid treatment, the antigenic decline rates of ALA and BLG upon alcalase hydrolysis were 82.82% and 88.01%, and that of the papain hydrolysis was 81.87% and 88.46%, respectively. Upon ultrasonic-ionic liquid pretreatment, the molecular weight of whey protein did not change significantly, but the small molecular weight proportion of components in the enzymatic hydrolysate obviously increased. The findings showed that combining with US-IL pretreatment for further protease hydrolysis of whey proteins, the hydrolysate can be used in order to produce hypoallergenic bovine whey proteins.

Novel activity of Streptomyces aminopeptidase P

Streptomyces aminopeptidase P enzymes are proline-specific peptidases that belong to the peptidase M24 family. To evaluate the activity of a commercial Streptomyces aminopeptidase P, named ‘XPO DUET’, we performed three experiments involving degradation of tryptic casein, production of free amino acids from casein hydrolysate, and hydrolysis of synthetic peptides. Using an ion-trap liquid chromatography–mass spectrometry (LC–MS) apparatus, we demonstrate that XPO DUET could degrade FFVAPFPEVFGK, an allergic and bitter peptide, VAPFPEVFGK, and PEVFGK from tryptic casein. All amino acids, except Ala, Asp, Glu, and Tyr, were released in an XPO DUET activity-dependent manner during the hydrolysis of casein hydrolysate. LC–MS analysis also revealed the ability of XPO DUET to completely hydrolyze Phe-Phe-Phe into free Phe. Thus, we confirm that XPO DUET possesses broader specificity than its known activity toward Xaa-Pro peptides. Because XPO DUET is a food-grade peptidase, it is useful in the bioprocessing of protein hydrolysates through its combination with other food-grade peptidases.

Influence of whey protein hydrolysis in combination with dextran glycation on immunoglobulin E binding capacity with blood sera obtained from patients with a cow milk protein allergy

Food protein allergies are a major global concern. Hydrolysis of food proteins reduces their allergenicity, but another novel approach is the covalent attachment of polysaccharides to proteins via the Maillard reaction (i.e., glycation), which blocks some IgE binding epitopes on the protein allergen. We wanted to examine whether enzymatic hydrolysis, combined with glycation, could further reduce IgE binding for people with a cow milk protein allergy. Whey protein isolate (WPI) was hydrolyzed by immobilized trypsin and chymotrypsin to degree of hydrolysis (DH) values of 17 to 27%. Immobilized enzymes were used to avoid heat-treating the hydrolysate (to inactivate the enzymes, because heating could also affect the IgE binding ability of the protein). The resultant whey protein isolate hydrolysates (WPIH) were then glycated with 10-kDa dextran (DX) in aqueous solutions held at 62°C for 24 h. We analyzed the molar mass (M_W) of WPIH samples and their corresponding glycates (WPIH-DX) using size-exclusion chromatography with multi-angle laser light scattering. We obtained blood sera from 8 patients who had been diagnosed with a cow milk protein allergy, and we used a composite serum for IgE binding analysis. The average M_W values of samples WPIH-1 to WPIH-3 decreased from 11.15, 9.46, and 7.57 kDa with increasing DH values of 18.7, 22.5, and 27.1%. Glycation significantly reduced the high bitterness of the WPIH samples, as assessed by a trained sensory panel. The WPIH-DX glycates had significantly reduced WPI-specific IgE binding capacity compared to WPI or unglycated WPIH; we found an almost 99% reduction in IgE binding for the WPIH-DX glycate made from WPIH with a DH value of 27.1%. Hydrolysis of WPI followed by glycation with DX via the Maillard reaction significantly decreased the allergenicity of whey proteins.

A Case of Anaphylaxis to Measles Vaccination in an Infant with Cow's Milk Allergy

Background: Cow's milk is one of the most common of the foods that cause food allergies in children. Here, we present a 10-month-old male who was diagnosed with having an allergy to cow's milk and who developed an anaphylactic reaction after being recently vaccinated with a measles vaccine. Case: The patient had been diagnosed with atopic dermatitis and cow's milk allergy at 40 days old after a rash appeared on his face and arms while exclusively breastfeeding. At 9 months, on his routine welfare outpatient appointment, he developed a facial rash and swelling, wheezing, difficulty breathing, and cyanosis within 10 min of having his first measles vaccination (M-VAC^®; Serum Institute of India, Hadapsar, Pune, India). After an allergy evaluation and a physical examination that showed that he was otherwise healthy, he was diagnosed with an allergy to cow's milk, which was then eliminated from his diet. Laboratory evaluations were as follows: serum immunoglobulin E (IgE) to cow's milk: 36.2 kU/L, α-lactalbumin: 9.39 kU/L, β-lactoglobulin: 8.74 kU/L, casein: 34.2 kU/L, latex-specific (sp)IgE: 0.10 kU/L, gelatin spIgE: <0.35 kU/L (normal levels <0.35 kU/L; Pharmacia, Uppsala, Sweden). Results revealed lactalbumin hydrolysate as one of the M-VAC ingredients according to the manufacturer's package insert. Conclusion: In most cases with a cow's milk allergy, vaccines are administered without any problems because the amount of milk proteins contained in the vaccines is not sufficient to represent a risk factor for anaphylaxis; however, the vaccine content should be examined for possible allergens, particularly for children with food allergies, before vaccinating. We should keep in mind when determining the agent responsible for an allergic reaction that the risk from a residual component of milk protein in vaccines can differ according to the nutritional habits of the population.

Reduced IgE/IgG binding capacities of bovine α-Lactalbumin by glycation after dynamic high-pressure microfluidization pretreatment evaluated by high resolution mass spectrometry

Dynamic high-pressure microfluidization (DHPM) pretreatment and glycation with lactose were employed to modify α-Lactalbumin (α-LA) with respect to the IgE/IgG binding capacities. No significant difference on incorporation ratio value of glycated α-LA was observed with and without DHPM pretreatment. However, IgE/IgG binding capacities of α-LA were decreased after glycation and DHPM pretreatment promoted the reduction. The lowest IgE/IgG binding capacities of glycated α-LA were obtained by DHPM pretreatment at 110 MPa. Native α-LA was mainly glycated at K62, K94, K98, whereas glycation sites and degree of substitution per peptide (DSP) were added after DHPM treatment. Therefore, the reduced IgE/IgG binding capacities of α-LA was attributed to the characteristics of glycated sites, including the amount, location, and DSP values. Interestingly, K98 played the most important role in decreasing IgE/IgG binding capacities of α-LA. The study revealed that glycation combined with DHPM was a promising way to decrease the allergenicity of proteins.

Molecular Approaches for Diagnosis, Therapy and Prevention of Cow´s Milk Allergy

Cow´s milk is one of the most important and basic nutrients introduced early in life in our diet but can induce IgE-associated allergy. IgE-associated allergy to cow´s milk can cause severe allergic manifestations in the gut, skin and even in the respiratory tract and may lead to life-threatening anaphylactic shock due to the stability of certain cow´s milk allergens. Here, we provide an overview about the allergen molecules in cow´s milk and the advantages of the molecular diagnosis of IgE sensitization to cow´s milk by serology. In addition, we review current strategies for prevention and treatment of cow´s milk allergy and discuss how they could be improved in the future by innovative molecular approaches that are based on defined recombinant allergens, recombinant hypoallergenic allergen derivatives and synthetic peptides.

Effect of thermal and microwave processing on secondary structure of bovine β-lactoglobulin: A molecular modeling study

Milk allergy is known to cause severe allergic reactions in hypersensitive patients, especially in infants and children. β-Lactoglobulin is one of the major allergens in bovine milk. The influence of thermal and microwave processing on the structural deviations of β-lactoglobulin protein have been studied using molecular modeling techniques. The structural deviations are studied using root mean square deviations, radius of gyration, dipole moment, and solvent accessible surface area. STRIDE analysis showed significant changes in the β-lactoglobulin, especially when oscillating electric fields were applied along with heat. Root mean square fluctuations (RMSF) has been assessed for known epitopes in the β-lactoglobulin molecule. This showed that when the protein is exposed to certain thermal stress, it compacts by burying hydrophobic residues in the core. However, few allergic epitope residues also exhibit increased RMSF leading to higher reactive sites on the surface of the protein molecule. PRACTICAL APPLICATIONS: This study showed that molecular modeling can be used to gain valuable insights regarding the structural changes during processing. In the future, with more computational capacity, it can be used to make comparison between results obtained from simulations and real-time experiments. The current techniques used in food industries such as Nuclear Magnetic Resonance Imaging, Fourier Transformation Infrared Spectroscopy, X-ray diffraction can analyze pre- and post-processing effects. Hence, it become necessary to understand the changes that takes place during the processing techniques. Molecular dynamic simulation could be a useful technique in analyzing the changes occurring during the processing.

Evaluation of the efficiency of hydrolyzed whey formula to prevent cow's milk allergy in the BALB/c mouse model

BACKGROUND

Partially hydrolyzed milk formulas have been proposed for primary prevention in at-risk infants, but evidence of their efficiency and elucidation of the underlying mechanisms are still lacking. Thanks to a Th2-biased mouse model mimicking at-risk patients, we aimed to assess the potency of a partially hydrolyzed whey formula (pHWF) to induce oral tolerance thus preventing further cow's milk (CM) allergy.

METHODS

BALB/c mice were gavaged with pHWF, standard milk formula (SF), or vehicle only (PBS+). All mice were then orally sensitized to CM using cholera toxin and further chronically exposed to CM. Humoral (IgE, IgG1, IgG2a) and cellular (Th2/Th1/Th17 cytokine secretion; frequency of CD4+GATA3+ and CD4+CD25+Foxp3+ T cells in the spleen) responses against β-lactoglobulin (BLG) and whole caseins (CAS) were assessed, as well as a marker of elicitation of allergic reaction (mMCP-1) released after an oral challenge with CM.

RESULTS

All markers of sensitization and of allergic reaction were evidenced in the PBS+ mice and were significantly enhanced upon chronic exposure. Gavage with SF totally and durably prevented sensitization and elicitation of the allergic reaction. Conversely, pre-treatment with pHWF only reduced BLG-specific sensitization (IgE, Th2 cytokines), with no significant effect on sensitization to caseins. However, pHWF pre-treatment significantly reduced mMCP-1 concentration in plasma after CM challenges. CD4+CD25+Foxp3+ Treg cell frequency could not be correlated with tolerance efficiency.

CONCLUSION

Partially hydrolyzed whey formula only partially prevents the further development of CM allergy in this Th2-biased model. A hydrolysate from both whey and casein fractions may be more efficient.

Production of hypoallergenic milk from DNA-free beta-lactoglobulin (BLG) gene knockout cow using zinc-finger nucleases mRNA

The whey protein β-lactoglobulin (BLG) is a major milk allergen which is absent in human milk. Here, we for the first time generated DNA-free BLG bi-allelic knockout cow by zinc-finger nuclease (ZFNs) mRNA and produced BLG-free milk. According to the allergenicity evaluation of BLG-free milk, we found it can trigger lower allergic reaction of Balb/c mice including the rectal temperature drop and the allergen-specific immunoglobulin IgE production; BLG free-milk was easily digested by pepsin at 2 min, while BLG in control milk was still not completely digested after 60 min, and the binding of IgE from cow's milk allergy (CMA) patients to BLG free-milk was significantly lower than that to the control milk. Meanwhile, the genome sequencing revealed that our animal is free of off-target events. Importantly, editing animal genomes without introducing foreign DNA into cells may alleviate regulatory concerns related to foods produced by genome edited animals. Finally, the ZFNs-mediated targeting in cow could be transmitted through the germline by breeding. These findings will open up unlimited possibilities of modifying milk composition to make it more suitable for human health and also improve the functional properties of milk.

Ultrasonic Pretreatment Combined with Dry-State Glycation Reduced the Immunoglobulin E/Immunoglobulin G-Binding Ability of α-Lactalbumin Revealed by High-Resolution Mass Spectrometry

Bovine α-lactalbumin (α-LA) is one of major food allergens in cow's milk. The present work sought to research the effects of ultrasonic pretreatment combined with dry heating-induced glycation between α-LA and galactose on the immunoglobulin E (IgE)/immunoglobulin G (IgG)-binding ability and glycation extent of α-LA, determined by inhibition enzyme-linked immunosorbent assay and high-resolution mass spectrometry, respectively. The IgE/IgG-binding ability of glycated α-LA was significantly decreased as a result of ultrasonic pretreatment, while the average molecular weight, incorporation ratio (IR) value, location and number of glycation sites, and degree of substitution per peptide (DSP) value were elevated. When the mixtures of α-LA and galactose were pretreated by ultrasonication at 150 W/cm², glycated α-LA possesses seven glycation sites, the highest IR and DSP values, and the lowest IgE/IgG-binding ability. Therefore, the decrease in the IgE/IgG-binding ability of α-LA depends upon not only the shielding effect of the linear epitope found to be caused by the glycation of K13, K16, K58, K93, and K98 sites but also the intensified glycation extent, which reflected in the increase of the IR value, the number of glycation sites, and the DSP value. Moreover, allergenic proteins and monosaccharides pretreated by ultrasonication and then followed by dry-state glycation were revealed as a promising way of achieving lower allergenicity of proteins in food processing.

Proteomics: a tool to develop novel diagnostic methods and unravel molecular mechanisms of pediatric diseases

Proteomics is the study of the expression of changes and post-translational modifications (PTM) of proteins along a metabolic condition either normal or pathological. In the field of health, proteomics allows obtaining valuable data for treatment, diagnosis or pathophysiological mechanisms of different illnesses. To illustrate the aforementioned, we describe two projects currently being performed at the Instituto Nacional de Pediatría: The immuno-proteomic study of cow milk allergy and the Proteomic study of childhood cataract. Cow's milk proteins (CMP) are the first antigens to which infants are exposed and generate allergy in some of them. In Mexico, the incidence of CMP allergy has been estimated at 5-7%. Clinical manifestations include both gastrointestinal and extra-gastrointestinal symptoms, making its diagnosis extremely difficult. An inappropriate diagnosis affects the development and growth of children. The goals of the study are to identify the main immune-reactive CMP in Mexican pediatric population and to design more accurate diagnostic tools for this disease. Childhood cataract is a major ocular disease representing one of the main causes of blindness in infants; in developing countries, this disease promotes up to 27% of cases related to visual loss. From this group, it has been estimated that close to 60% of children do not survive beyond two years after vision lost. PTM have been pointed out as the main cause of protein precipitation at the crystalline and, consequently, clouding of this tissue. The study of childhood cataract represents an outstanding opportunity to identify the PTM associated to the cataract-genesis process.

Preventive effects of royal jelly against anaphylactic response in a murine model of cow's milk allergy

CONTEXT

Royal jelly (RJ) has long been used to promote human health.

OBJECTIVE

The current study investigated the preventive effects of RJ against the development of a systemic and intestinal immune response in mice allergic to cow's milk proteins.

MATERIALS AND METHODS

Balb/c mice treated orally for seven days with RJ at doses of 0.5, 1 and 1.5 g/kg were sensitized intraperitoneally with β-lactoglobulin (β-Lg). Serum IgG and IgE anti-β-Lg were determined by an enzyme-linked immunosorbent assay (ELISA). Plasma histamine levels, symptom scores and body temperature were determined after in vivo challenge to β-Lg. Jejunums were used for assessment of local anaphylactic responses by an ex vivo study in Ussing chambers and morphologic changes by histological analysis.

RESULTS

RJ significantly decreased serum IgG (31.15-43.78%) and IgE (64.28-66.6%) anti-β-Lg and effectively reduced plasma histamine level (66.62-67.36%) (p < 0.001) at all the doses tested. Additionally, no clinical symptoms or body temperature drops were observed in RJ-pretreated mice. Interestingly, RJ significantly reduced (p < 0.001) intestinal dysfunction by abolishing the secretory response (70.73-72.23%) induced by sensitization and prevented length aberrations of jejunal villi by 44.32-59.01% (p < 0.001).

DISCUSSION AND CONCLUSIONS

We speculate that using RJ may help prevent systemic and anaphylactic response in allergic mice. These effects may be related to its inhibitory effects on the degranulation of mast cells.

Generation of beta-lactoglobulin knock-out goats using CRISPR/Cas9

Goat's milk, considered a substitute for cow's milk, has a high nutritional value. However, goat's milk contains various allergens, predominantly β-lactoglobulin (BLG). In this study, we employed the CRISPR/Cas9 system to target the BLG locus in goat fibroblasts for sgRNA optimization and generate BLG knock-out goats through co-injection of Cas9 mRNA and small guide RNAs (sgRNAs) into goat embryos at the one-cell stage. We firstly tested sgRNA editing efficiencies in goat fibroblast cells, and approximately 8.00%-9.09% of the cells were modified in single sgRNA-guided targeting experiment. Among the kids, the genome-targeting efficiencies of single sgRNA were 12.5% (10 ng/μL sg1) and 0% (10 ng/μL sg2) and efficiencies of dual sgRNAs were 25.0% (25 ng/μL sg2+sg3 group) and 28.6% (50 ng/μL sg2+sg3 group). Relative expression of BLG in BLG knock-out goat mammary glands significantly (p < 0.01) decreased as well as other milk protein coding genes, such as CSN1S1, CSN1S2, CSN2, CSN3 and LALBA (p < 0.05). As expected, BLG protein had been abolished in the milk of the BLG knock-out goat. In addition, most of the targeted kids were chimeric (3/4), and their various body tissues were edited simultaneously. Our study thus provides a basis for optimizing the quality of goat milk, which can be applied to biomedical and agricultural research.

The Reduction in the IgE-Binding Ability of β-Lactoglobulin by Dynamic High-Pressure Microfluidization Coupled with Glycation Treatment Revealed by High-Resolution Mass Spectrometry

Our previous study indicated that pretreatment by dynamic high-pressure microfluidization (DHPM) and glycation with galactose was a promising method for decreasing the immunoglobulin E (IgE)-binding ability of β-lactoglobulin (β-LG). In this work, the conformational alteration of β-LG subjected to DHPM and glycation treatment was investigated in relation to IgE-binding ability by orbitrap mass spectrometry. After DHPM pretreatment, lower IgE-binding ability of glycated β-LG was observed with increasing pressures. Prior to DHPM pretreatment, 11 glycated sites were identified, while the number of glycation sites was increased to 12 after pretreatment. However, there was no significant difference of the glycation sites at the pressures of 50, 100, and 200 MPa, respectively. Average degree of substitution per peptide molecule of β-LG (DSP) was investigated to assess the degree of glycation per glycation site. All of the samples pretreated by DHPM exhibited a higher glycation level than those without DHPM pretreatment. The shielding effects of epitopes owing to glycation contributed to the reduction of IgE-binding capacity. Orbitrap mass spectrometry could provide a comprehensive understanding of the nature of protein glycation.

Characterizing a region on BTA11 affecting β-lactoglobulin content of milk using high-density genotyping and haplotype grouping

Background

Milk β-lactoglobulin (β-LG) content is of interest as it is associated with nutritional and manufacturing properties. It is known that milk β-LG content is strongly affected by genetic factors. In cattle, most of the genetic differences are associated with a chromosomal region on BTA11, which contains the β-LG gene. The aim of this study was to characterize this region using 777 k SNP data (BovineHDbeadChip) and perform a haplotype-based association study. A statistical approach was developed to build haplotypes that capture the genetic variation associated with this genomic region.

Results

The SNP with the most significant effect on β-lactoglobulin content was one of the 2 causal mutations responsible for the β-lactoglobulin protein variants A/B. Haplotypes based on 2 to 5 selected lead SNP were clustered in groups with different effects on β-lactoglobulin content. Four different groups were identified suggesting that β-lactoglobulin variant A and B can be further refined in A₁, A₂, B₁ and B₂.

Conclusions

This study showed that β-lactoglobulin protein variants A/B do not explain all genetic variation associated with the tail part of BTA11 but this region contains more than one mutation with an effect on β-lactoglobulin content. These findings can be used for selection of cows with higher cheese yield, which is desirable for the dairy industry.

β-Lactoglobulin mutant Lys69Asn has attenuated IgE and increased retinol binding activity

β-Lactoglobulin (β-LG) is a member of lipocalin superfamily of transporters for small hydrophobic molecules such as retinoids, fatty acids, drugs, and vitamins. β-LG also is one of the major allergens in milk. Despite a lot of research on decreasing cow's milk allergenicity, the effects of mutations of β-LG on recognition by IgE from cow's milk allergy (CMA) patients have not been investigated. We describe here the expression in the yeast Pichia pastoris of a mutant bovine β-LG, in which lysine at position 69, in the main epitopes of the protein, was changed into asparagine (Lys69Asn). The purity and native like folded structure of the recombinant Lys69Asn β-LG was confirmed by HPLC, SDS-PAGE, mass spectrometry and circular dichroism. Lys69Asn β-LG has a fourfold stronger affinity than the wild-type protein for retinol, palmitic acid, and resveratrol, as determined by quenching of the intrinsic tryptophan fluorescence. At the same time the Lys69Asn mutant had a 9 fold attenuated, compared with the wild-type, affinity for IgE of sera from patients suffering from cow's milk allergy, whereas no difference could be detected between mutant and wild-type for binding of the IgGs of four monoclonal antibodies. The results of this study demonstrated the significant role of Lys69 residue on the binding and immuoreactivity properties of β-LG.

β-lactoglobulin mutation Ala86Gln improves its ligand binding and reduces its immunoreactivity

β-Lactoglobulin (β-LG) is a member of lipocalin superfamily of transporters for small hydrophobic molecules. β-LG is also one of the major allergens in milk. Despite a lot of researches on decreasing of cow's milk allergenicity, the effects of the mutation of β-LG on its recognition by IgE from cow's milk allergy (CMA) patients have not been investigated. We described here the expression in the yeast Pichia pastoris of a mutant β-LG, in which Alanine 86 was changed into Glutamine (Ala86Gln; a mutation on one of the major epitopes of the protein). The purity and native like folded structure of the recombinant Ala86Gln have been demonstrated using circular dichroism, HPLC, SDS-PAGE and mass spectrometry. The effect of the mutation on the binding of IgE from CMA patients to mutant protein was evaluated by ELISA methods and the results showed that the mutation of Ala-86 was associated with weaker binding of IgE from CMA patients to Ala86Gln mutant protein. Subsequently, the binding of various ligands such as retinol, palmitic acid, resveratrol and serotonin, with native, recombinant wild type and Ala86Gln mutant β-LGs were investigated by fluorescence spectroscopy and an improvement on the binding affinity of the mutated protein to various ligands was observed.

Characterization of the Immunogenicity and Allergenicity of Two Cow's Milk Hydrolysates--A Study in Brown Norway Rats

Hypoallergenic infant formulas based on hydrolysed milk proteins are used in the diet for cow's milk allergic infants. For a preclinical evaluation of the immunogenicity and allergenicity of new protein ingredients for such hypoallergenic infant formulas as well as for the investigation of which characteristics of hydrolysates that contribute to allergenicity, in vivo models are valuable tools. In this study, we examine the immunogenicity and allergenicity of two hydrolysates in a Brown Norway (BN) rat model, using i.p. dosing, which allows for the use of small quantities. Intact BLG, hydrolysed BLG and a hydrolysed whey product suitable for use in extensively hydrolysed formulas were thoroughly characterized for protein chemical features and administered to BN rats by i.p. immunization with or without adjuvant. Sera were analysed for specific IgG and IgE for evaluation of sensitizing capacity, immunogenicity and antibody-binding capacity. For evaluation of eliciting capacity a skin test was performed. The study showed that the hydrolysates had no residual allergenicity, lacking the capacity to sensitize and elicit reactions in the BN rats. Dosing with or without adjuvant induced a large difference in immunogenicity. Only antibodies from rats sensitized to intact BLG with adjuvant were able to bind the hydrolysates, and the whey-based hydrolysate only showed immunogenicity when dosed with adjuvant. This study showed that hydrolysates can be evaluated by an i.p. animal model, but that the choice of in vitro tests used for evaluation of antibody responses may greatly influence the result as well as may the use of adjuvant.

The impact of structural integrity and route of administration on the antibody specificity against three cow's milk allergens - a study in Brown Norway rats

Background

Characterisation of the specific antibody response, including the epitope binding pattern, is an essential task for understanding the molecular mechanisms of food allergy. Examination of antibody formation in a controlled environment requires animal models. The purpose of this study was to examine the amount and types of antibodies raised against three cow’s milk allergens; β-lactoglobulin (BLG), α-lactalbumin (ALA) and β-casein upon oral or intraperitoneal (i.p.) administration. A special focus was given to the relative amount of antibodies raised against linear versus conformational epitopes.

Methods

Specific antibodies were raised in Brown Norway (BN) rats. BN rats were dosed either (1) i.p. with the purified native cow’s milk allergens or (2) orally with skimmed milk powder (SMP) alone or together with gluten, without the use of adjuvants. The allergens were denatured by reduction and alkylation, resulting in unfolding of the primary structure and a consequential loss of conformational epitopes. The specific IgG1 and IgE responses were analysed against both the native and denatured form of the three cow’s milk allergens, thus allowing examination of the relative amount of linear versus conformational epitopes.

Results

The inherent capacity to induce specific IgG1 and IgE antibodies were rather similar upon i.p. administration for the three cow’s milk allergens, with BLG = ALA > β-casein. Larger differences were found between the allergens upon oral administration, with BLG > ALA > β-casein. Co-administration of SMP and gluten had a great impact on the specific antibody response, resulting in a significant reduced amount of antibodies. Together results indicated that most antibodies were raised against conformational epitopes irrespectively of the administration route, though the relative proportions between linear and conformational epitopes differed remarkably between the allergens.

Conclusions

This study showed that the three-dimensional (3D) structure has a significant impact on the antibodies raised for both systemic and orally administered allergens. A remarkable difference in the antibody binding patterns against linear and conformational epitope was seen between the allergens, indicating that the structural characteristics of proteins may heavily affect the induced antibody response.