Do mucosal biomarkers reveal the immunological state associated with food allergy?

Oral Mucosa as a Potential Site for Diagnosis and Treatment of Allergic and Autoimmune Diseases

Most prevalent food allergies during early childhood are caused by foods with a high allergenic protein content, such as milk, egg, nuts, or fish. In older subjects, some respiratory allergies progressively lead to food-induced allergic reactions, which can be severe, such as urticaria or asthma. Oral mucosa remodeling has been recently proven to be a feature of severe allergic phenotypes and autoimmune diseases. This remodeling process includes epithelial barrier disruption and the release of inflammatory signals. Although little is known about the immune processes taking place in the oral mucosa, there are a few reports describing the oral mucosa-associated immune system. In this review, we will provide an overview of the recent knowledge about the role of the oral mucosa in food-induced allergic reactions, as well as in severe respiratory allergies or food-induced autoimmune diseases, such as celiac disease.

Novel diagnostic techniques and therapeutic strategies for IgE-mediated food allergy

Background: Immunoglobulin E (IgE) mediated food allergy is a potentially life-threatening condition and represents a heavy burden for patients and their families. Identification of the most suitable way for management of each patient has currently become the primary goal for physicians. Methods: This study reviewed the current literature related to IgE-mediated food allergy. Results: The use of innovative diagnostic tools, such as allergen-specific IgG4 determination, basophil activation test, and component-resolved diagnostics, is currently available to facilitate a proper diagnosis of food allergy. After several decades of "passive clinical management" of the disease, which was based only on avoidance of the allergenic food and the use of epinephrine in the event of anaphylaxis, there has been a switch to active treatment. The most recent evidence-practice guidelines strongly recommend the use of immunotherapy as an effective therapeutic option, particularly in cases of allergy to cow's milk, egg, or peanut. The use of omalizumab, in association with immunotherapy or alone, has been tested in several studies, and results on its effectiveness seemed to be encouraging. Other biologics, such as dupilumab, reslizumab, mepolizumab, and other anticytokines therapies, are being investigated. Another interesting future treatment strategy could be the use of DNA vaccines. Conclusion: In recent years, the management of IgE-mediated food allergy has greatly improved. Knowledge of pathogenetic mechanisms, understanding of the disease course, and the introduction of novel biomarkers led to more accurate diagnoses along with the active treatment of patients.

Biomarkers for diagnosis and prediction of therapy responses in allergic diseases and asthma

Modern health care requires a proactive and individualized response to diseases, combining precision diagnosis and personalized treatment. Accordingly, the approach to patients with allergic diseases encompasses novel developments in the area of personalized medicine, disease phenotyping and endotyping, and the development and application of reliable biomarkers. A detailed clinical history and physical examination followed by the detection of IgE immunoreactivity against specific allergens still represents the state of the art. However, nowadays, further emphasis focuses on the optimization of diagnostic and therapeutic standards and a large number of studies have been investigating the biomarkers of allergic diseases, including asthma, atopic dermatitis, allergic rhinitis, food allergy, urticaria and anaphylaxis. Various biomarkers have been developed by omics technologies, some of which lead to a better classification of distinct phenotypes or endotypes. The introduction of biologicals to clinical practice increases the need for biomarkers for patient selection, prediction of outcomes and monitoring, to allow for an adequate choice of the duration of these costly and long‐lasting therapies. Escalating healthcare costs together with questions about the efficacy of the current management of allergic diseases require further development of a biomarker‐driven approach. Here, we review biomarkers in diagnosis and treatment of asthma, atopic dermatitis, allergic rhinitis, viral infections, chronic rhinosinusitis, food allergy, drug hypersensitivity and allergen immunotherapy with a special emphasis on specific IgE, the microbiome and the epithelial barrier. In addition, EAACI guidelines on biologicals are discussed within the perspective of biomarkers.

Advances and novel developments in molecular allergology

The continuous search for new allergens and the design of allergen derivatives improves the understanding of their allergenicity and aids the design of novel diagnostic and immunotherapy approaches. This article discusses the recent developments in allergen and epitope discovery, allergy diagnostics and immunotherapy. Structural information is crucial for the elucidation of cross-reactivity of marker allergens such as the walnut Jug r 6 or that of nonhomologous allergens, as shown for the peanut allergens Ara h 1 and 2. High-throughput sequencing, liposomal nanoallergen display, bead-based assays, and protein chimeras have been used in epitope discovery. The binding of natural ligands by the birch pollen allergen Bet v 1 or the mold allergen Alt a 1 increased the stability of these allergens, which is directly linked to their allergenicity. We also report recent findings on the use of component-resolved approaches, basophil activation test, and novel technologies for improvement of diagnostics. New strategies in allergen-specific immunotherapy have also emerged, such as the use of virus-like particles, biologics or novel adjuvants. The identification of dectin-1 as a key player in allergy to tropomyosins and the formyl peptide receptor 3 in allergy to lipocalins are outstanding examples of research into the mechanism of allergic sensitization.

Progress in understanding hypersensitivity reactions to nonsteroidal anti-inflammatory drugs

Nonsteroidal anti-inflammatory drugs (NSAIDs), the medications most commonly used for treating pain and inflammation, are the main triggers of drug hypersensitivity reactions. The latest classification of NSAIDs hypersensitivity by the European Academy of Allergy and Clinical Immunology (EAACI) differentiates between cross-hypersensitivity reactions (CRs), associated with COX-1 inhibition, and selective reactions, associated with immunological mechanisms. Three phenotypes fill into the first group: NSAIDs-exacerbated respiratory disease, NSAIDs-exacerbated cutaneous disease and NSAIDs-induced urticaria/angioedema. Two phenotypes fill into the second one: single-NSAID-induced urticaria/angioedema/anaphylaxis and single-NSAID-induced delayed reactions. Diagnosis of NSAIDs hypersensitivity is hampered by different factors, including the lack of validated in vitro biomarkers and the uselessness of skin tests. The advances achieved over recent years recommend a re-evaluation of the EAACI classification, as it does not consider other phenotypes such as blended reactions (coexistence of cutaneous and respiratory symptoms) or food-dependent NSAID-induced anaphylaxis. In addition, it does not regard the natural evolution of phenotypes and their potential interconversion, the development of tolerance over time or the role of atopy. Here, we address these topics. A state of the art on the underlying mechanisms and on the approaches for biomarkers discovery is also provided, including genetic studies and available information on transcriptomics and metabolomics.

Biomarkers in Food Allergy

PURPOSE OF REVIEW

To familiarize the reader with the concept of precision medicine in food allergy by dealing with the current biomarkers for the diagnosis, prognosis, and management of the disease.

RECENT FINDINGS

Many efforts have been devoted in order to characterize reliable biomarkers able to identify specific phenotypes and endotypes in food allergy. Specific IgE (sIgE), sIgE/total IgE ratios, and T cell assays are just a few candidates that have been investigated over time. With the advent of omics sciences, a new era is commencing. A better understanding of pathogenesis of food allergy and mechanisms of action of the different therapeutic options will allow the accurate selection of the appropriate patient. In the near future, advances in technologies and data interpretation will allow a better understanding of the pathogenesis of food allergy and the identification of proper biomarkers for a personalized treatment tailored on the specific patient's profile.