Contribution of Molecular Allergen Analysis in Diagnosis of Milk Allergy

Gene editing in allergic diseases: Identification of novel pathways and impact of deleting allergen genes

Gene editing technology has emerged as a powerful tool in all aspects of health research and continues to advance our understanding of critical and essential elements in disease pathophysiology. The clustered regularly interspaced short palindromic repeats (CRISPR) gene editing technology has been used with precision to generate gene knockouts, alter genes, and identify genes that cause disease. The full spectrum of allergic/atopic diseases, in part because of shared pathophysiology, is ripe for studies with this technology. In this way, novel culprit genes are being identified and allow for manipulation of triggering allergens to reduce allergenicity and disease. Notwithstanding current limitations on precision and potential off-target effects, newer approaches are rapidly being introduced to more fully understand specific gene functions as well as the consequences of genetic manipulation. In this review, we examine the impact of editing technologies of novel genes relevant to peanut allergy and asthma as well as how gene modification of common allergens may lead to the deletion of allergenic proteins.

Rapid authentication of characteristic milk powders by recombinase polymerase amplification assays

The authentication of dairy species has great significance for food safety. This study focused on a more rapid method for identifying major dairy species, and specific recombinase polymerase amplification (RPA)-based assays for cattle, goat, sheep, camel and donkey were developed. Through the developed RPA-based assays, goats and sheep could be simultaneously identified and bovine families could be differentiated. The performances of the RPA assays were validated using 37 milk powder samples, of which 16.2% (6/37) were suspected of being adulterated and 24.3% (9/37) were potentially at risk of being wrongly identified as adulteration. The effectiveness of the developed assays for crude DNA detection was also validated by a rapid nucleic acid extraction kit, and results showed that the presence of large amounts of protein and fat did not affect the qualitative results. Therefore, these assays could combine with the rapid nucleic acids extraction methods for being used in field detection.

The Need for Culturally Appropriate Food Allergy Management Strategies: The Indian Milk Ladder

BACKGROUND

Cow's milk allergy (CMA) is one of the most common and complex food allergies affecting children worldwide and, with a few exceptions, presents in the first few months of life. Baked-milk-containing diets are well tolerated in the majority of milk-allergic children and allow dietary restrictions to be relaxed. In addition, the early introduction of tolerated forms of allergenic foods to an infant's diet in small amounts may enhance the outgrowth of their milk allergy through oral tolerance induction. The methods of milk introduction vary widely across the globe.

METHODS

We convened an expert group to develop a comprehensive milk ladder based on the calculated milk protein content of Indian foods. To validate the milk ladder, the foods chosen for the ladder were analyzed and the ladder was re-evaluated based on the cooked milk protein content.

RESULTS

Combining expert consensus and validation of milk protein content, we created the world's first milk ladder containing Indian foods. This is the first ladder that provides information on the timing and temperature of cooking, with validated milk protein content.

CONCLUSIONS

This is the first milk ladder based on the unique features of Indian food habits built by the consensus of Indian experts along with international collaboration with laboratory quantification of milk protein in each step. We believe the "The Indian Milk Ladder" will be a very helpful tool for pediatricians helping manage CMA in children as well as their parents and caregivers, not only in India, but in countries world-wide where these foods are commonly consumed.

Patterned Biolayers of Protein Antigens for Label-Free Biosensing in Cow Milk Allergy

This paper focuses on creating one-dimensional diffractive grooved structures of antigen proteins on glass substrates for the label-free detection of antibodies to dairy allergens. In particular, the fabrication of protein structures is carried out by combining microcontact printing with physisorption, imines coupling, and thiol-ene click chemistry. The work first sets up these patterning methods and discusses and compares the main aspects involved in them (structure, biolayer thickness, functionality, stability). Homogeneous periodic submicron structures of proteins are created and characterized by diffractive measurements, AFM, FESEM, and fluorescence scanning. Then, this patterning method is applied to proteins involved in cow milk allergy, and the resulting structures are implemented as optical transducers to sense specific immunoglobulins G. In particular, gratings of bovine serum albumin, casein, and β-lactoglobulin are created and assessed, reaching limits of detection in the range of 30-45 ng·mL^-1 of unlabeled antibodies by diffractive biosensing.

Modern diagnostics in IgE-mediated cow’s milk allergy

Cow's milk allergy (CMA) is the most common food allergy in infants and young children. Allergic reactions can vary from mild to severe, like an anaphylactic shock. In case of CMA diagnosis suspicion skin prick tests (SPT), immunoassays of specific IgE (sIgE) in blood serum (in vitro tests) and oral food challenge (OFC) tests can be performed.  SPT wheal diameter and the level of serum specific IgE to milk do not correlate with severity of clinical symptoms, while procedure of OFC is often difficult or even imposible in practice. Therefore component resolved-diagnostics (CRD) tests are a new diagnostic tool, which allows for a better correlation of laboratory test results with the observed clinical symptoms and indicate the triggering allergens.

Introduction of Heated Cow's Milk Protein in Challenge-Proven Cow's Milk Allergic Children: The iAGE Study

The introduction of baked milk products in cow’s milk (CM) allergic children has previously been shown to accelerate induction tolerance in a selected group of children. However, there is no standardized baked milk product on the market. Recently, a new standardized, heated and glycated cow’s milk protein (HP) product was developed. The aim of this study was to measure safety and tolerability of a new, well characterized heated CM protein (HP) product in cow’s milk allergic (CMA) children between the age of 3 and 36 months. The children were recruited from seven clinics throughout The Netherlands. The HP product was introduced in six incremental doses under clinical supervision. Symptoms were registered after introduction of the HP product. Several questionnaires were filled out by parents of the children. Skin prick tests were performed with CM and HP product, sIgE to CM and α-lactalbumin (Bos d4), β-lactoglobulin (Bos d5), serum albumin (Bos d 6), lactoferrin (Bos d7) and casein (Bos d8). Whereas 72% percent (18 out of 25) of the children tolerated the HP product, seven children experienced adverse events. Risk factors for intolerance to the HP product were higher skin prick test (SPT) histamine equivalent index (HEP) results with CM and the HP product, higher specific IgE levels against Bos d4 and Bos d8 levels and Bos d5 levels. In conclusion, the HP product was tolerated by 72% of the CM allergic children. Outcomes of SPT with CM and the HP product, as well as values of sIgE against caseins, α-lactalbumin, and β-lactoglobulin may predict the tolerability of the HP product. Larger studies are needed to confirm these conclusions.

Extract and molecular-based early infant sensitization and associated factors-A PreventADALL study

BACKGROUND

More knowledge about sensitization patterns in early infancy, including impact of molecular allergology, is needed to help predict future allergy development more accurately.

OBJECTIVE

We aimed to determine the prevalence and patterns of allergic sensitization at 3 months of age, and explore possible associated factors.

METHODS

From the Scandinavian antenatally recruited PreventADALL mother-child cohort, we included 1110 3-month infants with available serum. Sensitization was defined as s-IgE of ≥0.1 kU_A /L by Phadiatop Infant^® (ThermoFisher Scientific) including birch, cat, grass, dog, milk, egg, peanut and wheat. Further ImmunoCAP analyses to ovomucoid, casein, Ara h 1-3, omega-5-gliadin were performed in food extract s-IgE-positive children. Maternal sensitization was defined as s-IgE ≥ 0.35 kU_A /L to Phadiatop^® (inhalant allergen mix) and/or Fx5 (food allergen mix) at 18-week pregnancy.

RESULTS

Overall 79 (7.3%) infants had specific sensitization, many with low s-IgE-levels (IQR 0.16-0.81 kU_A /L), with 78 being sensitized to food extract allergens; 41 to egg, 27 to milk, 10 to peanut, and 25 to wheat. A total of 62/78 were further analysed, 18 (29%) had s-IgE to ovomucoid, casein, Ara h 1-3 and/or omega-5-gliadin. Eight infants (0.7%) were sensitized to inhalant allergens. Maternal sensitization to food allergens was associated with infant sensitization, odds ratio 3.64 (95% CI 1.53-8.68).

CONCLUSION

Already at 3 months of age, 7% were sensitized to food, mostly without detectable s-IgE to food allergen molecules, and <1% to inhalant allergens. Maternal food sensitization was associated with infants' sensitization.

Design, quality, safety and efficacy of extensively hydrolyzed formula for management of cow's milk protein allergy: What are the challenges?

Cow's milk protein allergy (CMPA) is one of the most common food allergies in infancy. Clinical food allergy guidelines recommend an extensively hydrolyzed formula (EHF) as the first-line treatment in nonbreastfed infants with CMPA. Designing and commercializing EHF poses both technical and regulatory challenges. Each manufacturing step, from sourcing of raw materials to release of the final product, needs to be managed in accordance with comprehensive quality systems. To avoid cross-contamination via externally sourced ingredients, suppliers should be carefully selected based on quality requirements. Strict zoning of the manufacturing areas according to contamination risk and air flow control are effective strategies to prevent accidental allergen contamination. Furthermore, dedicated manufacturing lines for hypoallergenic products are used to prevent potential cross-contamination from other products produced on the same line. The enzymatic hydrolysis, heat treatment and ultrafiltration used are specific to each manufacturer. Consequently, EHF are a heterogenous group of products with differences in the molecular weight profile of peptides, content of residual immunogenic cow's milk allergens, and residual in-vitro allergenicity. These differences are likely to affect clinical efficacy and safety. As not all commercialized EHF products have undergone formal testing in the laboratory and clinical trials, there is a need to develop guidelines for minimum technical and regulatory requirements for EHF products, including validated assays for ongoing quality control. Clinical trials assessing new EHF products for their hypoallergenicity and ability to support normal growth remain the definitive proof of efficacy and safety in infants and young children with CMPA.

A WAO - ARIA - GA2LEN consensus document on molecular-based allergy diagnosis (PAMD@): Update 2020

Precision allergy molecular diagnostic applications (PAMD@) is increasingly entering routine care. Currently, more than 130 allergenic molecules from more than 50 allergy sources are commercially available for in vitro specific immunoglobulin E (sIgE) testing. Since the last publication of this consensus document, a great deal of new information has become available regarding this topic, with over 100 publications in the last year alone. It thus seems quite reasonable to publish an update. It is imperative that clinicians and immunologists specifically trained in allergology keep abreast of the new and rapidly evolving evidence available for PAMD@.

PAMD@ may initially appear complex to interpret; however, with increasing experience, the information gained provides relevant information for the allergist. This is especially true for food allergy, Hymenoptera allergy, and for the selection of allergen immunotherapy. Nevertheless, all sIgE tests, including PAMD@, should be evaluated within the framework of a patient's clinical history, because allergen sensitization does not necessarily imply clinical relevant allergies.

Component-Resolved Diagnosis in Food Allergies

Component-resolved diagnostics (CRD) in food allergies is an approach utilized to characterize the molecular components of each allergen involved in a specific IgE (sIgE)-mediated response. In the clinical practice, CRD can improve diagnostic accuracy and assist the physician in many aspects of the allergy work-up. CRD allows for discriminatory co-sensitization versus cross-sensitization phenomena and can be useful to stratify the clinical risk associated with a specific sensitization pattern, in addition to the oral food challenge (OFC). Despite this, there are still some unmet needs, such as the risk of over-prescribing unnecessary elimination diets and adrenaline auto-injectors. Moreover, up until now, none of the identified sIgE cutoff have shown a specificity and sensitivity profile as accurate as the OFC, which is the gold standard in diagnosing food allergies. In light of this, the aim of this review is to summarize the most relevant concepts in the field of CRD in food allergy and to provide a practical approach useful in clinical practice.

Detection of serum and salivary IgE and IgG1 immunoglobulins specific for diagnosis of food allergy

Given the growing incidence and prevalence of life-threatening food allergies, health concerns have raised new perspectives for in vivo and in vitro diagnostic methodologies, pointing to saliva as a promising material, already used to diagnose other pathologies. Based on the above considerations, this study aimed to verify the possible use of saliva for the detection of IgE and IgG₁ in the diagnosis of food allergy. This was a randomized, cross-sectional clinical study with a quantitative approach, developed at a hospital referral center in allergy in the state of Ceará, from January to July 2015. The sample consisted of 36 children of both sexes, aged between 1 and 60 months, with a diagnosis of cow's milk protein allergy (CMPA) by the RAST test. Children hospitalized or under immunosuppressive drugs were excluded from the study. Serum and saliva samples of the participants were collected and subsequently subjected to the indirect immunoenzymatic assay (ELISA) for the detection of specific serum and salivary immunoglobulins for food: corn, papaya, cow's milk, egg white, wheat, soybeans, peanuts, nuts, kiwi, cacao, fish, shrimp, bananas and tomatoes. For comparison of serum and saliva results, the T-test of independent samples and Mann-Whitney were adopted, for samples with normal and non-normal distribution respectively. A confidence interval of 95% was adopted for significant results. It was observed that 100% (n = 36) of the participants presented cow's milk allergy through the indirect ELISA, detecting IgE or IgG₁ in serum and saliva. When serum IgE and IgG₁ concentrations were compared, there was no statistical difference (p > 0.05) in 12 of the 14 foods evaluated. The same amount (n = 12) of non-significant differences (p > 0.05) was observed in the comparison of the 14 foods under IgE and IgG₁ contractions in saliva. In the verification of the average values of IgE present in the serum and saliva of the foods, only cow's milk, fish and papaya showed statistically significant differences (p < 0.05). Of the total food evaluated, only the average levels of IgG₁ present in serum and saliva showed a significant value (p < 0.05) in banana and tomato. These findings indicate that the detection of IgE and IgG₁ in saliva proves to be as efficient as in the serum. The use of the salivary technique for use in the diagnosis of food allergy is suggested.

The Impact of Baked Egg and Baked Milk Diets on IgE- and Non-IgE-Mediated Allergy

Baked milk (BM) and baked egg (BE) diets are increasingly used in the management of milk and egg allergy, rather than avoidance. Children with tolerance versus reactivity to BM and BE may have smaller skin prick test and lower specific IgE, and BM-tolerant children have less basophil reactivity and more peripheral T regulatory cells. However, most milk- and egg-allergic children tolerate BM and BE and an individual's reactivity is unpredictable. Non-reactivity is due to conformational changes in the allergens. Significant differences in the published advice about methods of introduction exist from graded introduction at home to a medically supervised full dose. These approaches carry different risks and may have different immunological effects. Reactivity to BM is a predictor of a severe milk allergy. Therefore, medical supervision for BM and BE introduction is prudent. The baked diet allows dietary liberation. Most, but not all, BM- and BE-tolerant children continue eating the baked foods. The prognosis of children who can eat BM and BE is favorable with likely resolution of their allergy over the next few years. Murine models of BE diets demonstrate that heated egg can impart clinical protection against anaphylaxis and cause immune changes. Most observational human studies of BM and BE diets demonstrate clinical resolution of allergy and favorable immune changes versus regular care controls. However, the one randomized controlled trial for the BE diet in BE-tolerant children did not support an immune-modifying effect of the BE diet. Another study of BE immunotherapy is expected to be completed in 2018. There is currently no evidence for prevention of allergy with the baked diets. There may be a future role for BM and BE in liberating the diets of individuals with non-IgE-mediated allergy given recent studies that a subset of these patients can consume BM without a clinical reaction.

Allergenicity reduction of bovine milk β-lactoglobulin by proteolytic activity of lactococcus lactis BMC12C and BMC19H isolated from Iranian dairy products

Nowadays health benefits of bioactive food constituents, known as probiotic microorganisms, are a growing awareness. Cow's milk is a nutritious food containing probiotic bacteria. However, milk allergenicity is one of the most common food allergies. The milk protein, β-lactoglobulin (BLG), is in about 80% of all main cases of milk allergies for children and infants. With the aim of screening proteolytic strains of lactic acid bacteria to evaluate their potential for the reduction of allergenicity of the major bovine milk proteins, we isolated new proteolytic strains of cocci lactic acid bacteria from traditional Iranian dairy products. The proteases produced by these strains had strong proteolytic activity against BLG. Proteolysis of BLG, observed after sodium dodecyl sulfate-PAGE, was confirmed by the analysis of the peptide profiles by reversed-phase HPLC. The two isolates were submitted to 16S rDNA sequencing and identified as Lactcoccus lactis subsp. cremoris and Lactcoccus lactis subsp. hordniea. The competitive ELISA experiments confirmed that these isolates, with high proteolytic activity, reduce significantly the allergenicity of BLG. Accordingly, these isolates can reduce the immunoreactivity of bovine milk proteins, which can be helpful for the production of low-allergic dairy products.

Regulatory Immune Mechanisms in Tolerance to Food Allergy

Oral tolerance can develop after frequent exposure to food allergens. Upon ingestion, food is digested into small protein fragments in the gastrointestinal tract. Small food particles are later absorbed into the human body. Interestingly, some of these ingested food proteins can cause allergic immune responses, which can lead to food allergy. So far it has not been completely elucidated how these proteins become immunogenic and cause food allergies. In contrast, oral tolerance helps to prevent the pathologic reactions against different types of food antigens from animal or plant origin. Tolerance to food is mainly acquired by dendritic cells, epithelial cells in the gut, and the gut microbiome. A subset of CD103⁺ DCs is capable of inducing T regulatory cells (Treg cells) that express anti-inflammatory cytokines. Anergic T cells also contribute to oral tolerance, by reducing the number of effector cells. Similar to Treg cells, B regulatory cells (Breg cells) suppress effector T cells and contribute to the immune tolerance to food allergens. Furthermore, the human microbiome is an essential mediator in the induction of oral tolerance or food allergy. In this review, we outline the current understanding of regulatory immune mechanisms in oral tolerance. The biological changes reflecting early consequences of immune stimulation with food allergens should provide useful information for the development of novel therapeutic treatments.