Immunology of Food Allergy

Lactic acid bacteria and yeast co-fermented milk alleviate cow milk allergy

Cow milk allergy is one of the common food allergies. Our previous study showed that the allergenicity of fermented milk is lower than that of unfermented skimmed milk in vitro, and the antigenicity of β-lactoglobulin and α-lactalbumin in fermented milk was decreased by 67.54% and 80.49%, respectively. To confirm its effects in vivo, allergic BALB/C mice model was used to further study the allergenicity of fermented milk. It was found that compared with the skim milk (SM) group, the intragastrically sensitization with fermented milk had no obvious allergic symptoms and the fingers were more stable: lower levels of IgE, IgG, and IgA in serum, lower levels of plasma histamine and mast cell protein-1, and immune balance of Th1/Th2 and Treg/Th17. At the same time, intragastrically sensitization with fermented milk increased the α diversity of intestinal microbiota and changed the microbiota abundance: the relative abundance of norank-f-Muribaculaceae and Staphylococcus significantly decreased, and the abundance of Lachnospiraceae NK4A136 group, Bacteroides, and Turicibacter increased. In addition, fermented milk can also increase the level of short-chain fatty acids in the intestines of mice. It turns out that fermented milk is much less allergenicity than SM. PRACTICAL APPLICATION: Fermentation provides a theoretical foundation for reducing the allergenicity of milk and dairy products, thereby facilitating the production of low-allergenic dairy products suitable for individuals with milk allergies.

Allergenicity and Linear Epitope Analysis of Scy p 8, an Allergen from Mud Crab

Scy p 8 (triosephosphate isomerase) as a crab allergen in inducing distinct T-helper (Th) cell differentiation and a linear epitope associated with allergenicity remain elusive. In this study, mice sensitized with Scy p 8 exhibited significantly upregulated levels of IgE, IgG1, and IL-4 release, inducing a Th2 immune response. Moreover, the release of IFN-γ (Th1) and the levels of Treg cells were downregulated, while IL-17A (Th17) was upregulated, indicating that Scy p 8 disrupted the Th1/Th2 balance and Th17/Treg balance in mice. Furthermore, bioinformatics prediction and serum samples from crab-allergic patients and mice enabled the discovery of 8 linear epitopes of Scy p 8. Meanwhile, the analysis of peptide similarity and tertiary superposition revealed that 8 epitopes of Scy p 8 exhibited conservation across various species, potentially resulting in cross-reactivity. These findings possess the potential to enhance the comprehension of crab allergens, thereby establishing a foundation for investigating cross-reactivity.

Moniezia benedeni infection increases IgE+ cells in sheep (Ovis aries) small intestine

The concentration of immunoglobulin (Ig) E is the lowest among serum Igs, but it can induces type I hypersensitivity and plays an important role in anti-parasitic infection. The present study aimed to explore the residence characteristics of IgE+ cells in the sheep small intestine and the impact of Moniezia benedeni infection on them. The recombinant plasmids pET-28a-IgE were constructed and induced and expressed in Escherichia coli. BL21 (DE3). The rabbit anti-sheep IgE polyclonal antibody was prepared using the obtained recombinant protein as antigen. Finally, the levels of IgE+ cells in the small intestine of healthy (Control group) and naturally M. benedeni-infected (Infected group) sheep were detected analyzed. The results showed that the rabbit anti-sheep IgE polyclonal antibody with good immunogenicity (titer = 1: 128000) could specifically bind to the heavy chain of natural sheep IgE. In the Control group, the IgE+ cells were mainly distributed in lamina propria of the small intestine, and the densities were significantly decreased from duodenum to ileum (P<0.05), with respective values of (4.28 cells / 104 μm2, 1.80 cells / 104 μm2, and 1.44 cells / 104 μm2 in duodenum, jejunum, and ileum. In the Infected group, IgE+ cells density were 6.26 cells / 104 μm2, 3.01 cells / 104 μm2, and 2.09 cells / 104 μm2 in duodenum, jejunum and ileum respectively, which were significantly higher in all segments compared to the Control group (P<0.05), increasing by 46.26%, 67.22% and 45.14%, respectively. In addition, compared with the Control group, the IgE protein levels were significantly increased in all intestinal segments of the Infected group (P<0.01), however, there was no significant differences among the different intestinal segments within the same group (P>0.05). The results demonstrated that M. benedeni infection could significantly increase the content of IgE and the distribution density of its secreting cells in sheep small intestine. The intestinal mucosal immune system of sheep presented obvious specificity against M. benedeni infection. This lays a good foundation for further exploring molecular mechanisms of the intestinal mucosal immune system monitoring and responding to M. benedeni infection.

Joint transcriptomic and cytometric study of children with peanut allergy reveals molecular and cellular cross talk in reaction thresholds

BACKGROUND

Reaction thresholds in peanut allergy are highly variable. Elucidating causal relationships between molecular and cellular processes associated with variable thresholds could point to therapeutic pathways for raising thresholds.

OBJECTIVE

The aim of this study was to characterize molecular and cellular systemic processes associated with reaction threshold in peanut allergy and causal relationships between them.

METHODS

A total of 105 children aged 4 to 14 years with suspected peanut allergy underwent double-blind, placebo-controlled food challenge to peanut. The cumulative peanut protein quantity eliciting allergic symptoms was considered the reaction threshold for each child. Peripheral blood samples collected at 0, 2, and 4 hours after challenge start were used for RNA sequencing, whole blood staining, and cytometry. Statistical and network analyses were performed to identify associations and causal mediation between the molecular and cellular profiles and peanut reaction threshold.

RESULTS

Within the cohort (N = 105), 81 children (77%) experienced allergic reactions after ingesting varying quantities of peanut, ranging from 43 to 9043 mg of cumulative peanut protein. Peripheral blood expression of transcripts (eg, IGF1R [false discovery rate (FDR) = 5.4e-5] and PADI4 [FDR = 5.4e-5]) and neutrophil abundance (FDR = 9.5e-4) were associated with peanut threshold. Coexpression network analyses revealed that the threshold-associated transcripts were enriched in modules for FcγR-mediated phagocytosis (FDR = 3.2e-3) and Toll-like receptor (FDR = 1.4e-3) signaling. Bayesian network, key driver, and causal mediation analyses identified key drivers (AP5B1, KLHL21, VASP, TPD52L2, and IGF2R) within these modules that are involved in bidirectional causal mediation relationships with neutrophil abundance.

CONCLUSION

Key driver transcripts in FcγR-mediated phagocytosis and Toll-like receptor signaling interact bidirectionally with neutrophils in peripheral blood and are associated with reaction threshold in peanut allergy.

Both live and heat killed Lactiplantibacillus plantarum DPUL-F232 alleviate whey protein-induced food allergy by regulating cellular immunity and repairing the intestinal barrier

Postbiotics have been proposed as clinically viable alternatives to probiotics, addressing limitations and safety concerns associated with probiotic use. However, direct comparisons between the functional differences and health benefits of probiotics and postbiotics remain scarce. This study compared directly the desensitization effect of probiotics and postbiotics derived from Lactiplantibacillus plantarum strain DPUL-F232 in the whey protein-induced allergic rat model. The results demonstrate that administering both live and heat killed F232 significantly alleviated allergy symptoms, reduced intestinal inflammation, and decreased serum antibody and histamine levels in rats. Both forms of F232 were effective in regulating the Th1/Th2 balance, promoting the secretion of the regulatory cytokine IL-10, inhibiting mast cell degranulation and restoring the integrity of the intestinal barrier through the upregulation of tight junction proteins. Considering the enhanced stability and reduced safety concerns of postbiotics compared to probiotics, alongside their ability to regulate allergic reactions, we suggest that postbiotics may serve as viable substitutes for probiotics in managing food allergies and potentially other diseases.

The riddle of response to cutaneous allergen exposure in patients with atopic dermatitis

The skin is the largest immunologic organ in the body and contains immune cells that play a role in both food allergen sensitization and desensitization. The dual allergen exposure hypothesis posits that sensitization to food allergens may occur with cutaneous exposure on inflamed skin, eg, atopic dermatitis, but early oral consumption generally leads to tolerance. However, only one-third of children with atopic dermatitis develop a food allergy, suggesting that there is a more complex mechanism for allergen sensitization. Emerging evidence suggests that the outcome of cutaneous allergen exposure is context-dependent and largely influenced by the state of the skin barrier with healthy skin promoting natural tolerance. Current research supports the ability to induce desensitization through repeated application of allergens to the skin, known as epicutaneous immunotherapy. Preclinical research with an occlusive patch has demonstrated a significantly reduced T-helper cell type 2-driven immunologic response when applied to intact, uninflamed skin and induction of a unique population of regulatory T cells that express a broader range of homing receptors, which may be able to maintain sustained protection. In clinical studies of children aged 1 through 11 years with a peanut allergy, epicutaneous immunotherapy with an occlusive patch led to significant desensitization with no major differences in efficacy or safety between children with and without atopic dermatitis. These data begin to answer the conundrum of how allergens that are applied to the skin can lead to both sensitization and desensitization, and future studies should enable us to optimize the power of the skin as a complex immunologic organ to treat allergic, autoimmune, and autoinflammatory disorders.

RAG suppresses group 2 innate lymphoid cells

Antigen specificity is the central trait distinguishing adaptive from innate immune function. Assembly of antigen-specific T cell and B cell receptors occurs through V(D)J recombination mediated by the Recombinase Activating Gene endonucleases RAG1 and RAG2 (collectively called RAG). In the absence of RAG, mature T and B cells do not develop and thus RAG is critically associated with adaptive immune function. In addition to adaptive T helper 2 (Th2) cells, group 2 innate lymphoid cells (ILC2s) contribute to type 2 immune responses by producing cytokines like Interleukin-5 (IL-5) and IL-13. Although it has been reported that RAG expression modulates the function of innate natural killer (NK) cells, whether other innate immune cells such as ILC2s are affected by RAG remains unclear. We find that in RAG-deficient mice, ILC2 populations expand and produce increased IL-5 and IL-13 at steady state and contribute to increased inflammation in atopic dermatitis (AD)-like disease. Further, we show that RAG modulates ILC2 function in a cell-intrinsic manner independent of the absence or presence of adaptive T and B lymphocytes. Lastly, employing multiomic single cell analyses of RAG1 lineage-traced cells, we identify key transcriptional and epigenomic ILC2 functional programs that are suppressed by a history of RAG expression. Collectively, our data reveal a novel role for RAG in modulating innate type 2 immunity through suppression of ILC2s.

Production and use of antigen tetramers to study antigen-specific B cells

B cells generate antibodies that provide protection from infection, but also cause pathology in autoimmune and allergic conditions. Antigen-specific B cells can be detected by binding their surface antibody receptors with native antigens conjugated to fluorescent probes, a technique that has revealed substantial insight into B cell activation and function. This protocol describes the process of generating fluorescent antigen tetramer probes and delineates a process of enriching large samples based on antigen-specificity for high-resolution analyses of the antigen-specific B cell repertoire. Enrichment of tetramer-binding cells allows for detection of antigen-specific B cells as rare as 1 in 100 million cells, providing sufficient resolution to study naive B cells and IgE-expressing cells by flow cytometry. The generation of antigen tetramers involves antigen biotinylation, assessment of biotin:antigen ratio for optimal tetramer loading and polymerization around a streptavidin-fluorophore backbone. We also describe the construction of a control tetramer to exclude B cells binding to the tetramer backbone. We provide a framework to validate whether tetramer probes are detecting true antigen-specific B cells and discuss considerations for experimental design. This protocol can be performed by researchers trained in basic biomedical/immunological research techniques, using instrumentation commonly found in most laboratories. Constructing the antigen and control tetramers takes 9 h, though their specificity should be assessed before experimentation and may take weeks to months depending on the method of validation. Sample enrichment requires ~2 h but is generally time and cost neutral as fewer cells are run through the flow cytometer.

Optimising the management of peanut allergy by targeting immune plasticity

Randomised controlled trials investigating the efficacy of oral tolerance induction to peanut have enabled detailed comparison of their clinical and immunological success. They have demonstrated that the regular consumption of peanut for at least 2 years by babies who are not allergic enables protection from developing peanut allergy. The LEAP study intervention tested the impact of regular peanut consumption for 4 years and demonstrated a sustained protection against the development of peanut allergy even after 12 months of peanut avoidance from 5 to 6 years of age. The PreventADALL trial introduced multiple allergens into babies' diets from early infancy and reduced the prevalence of food allergy at 3 years, especially by protecting against peanut allergy. Immunological studies from the LEAP cohort demonstrated that regular peanut consumption was associated with a prompt induction of peanut-specific IgG4 and reduced manufacture of peanut and Ara h 2-specific IgE. Even after stopping peanut consumption for 5 years, there continued to be a significant fall in peanut-specific Ara h 2 IgE in the consumption group from 5 to 6 years of age (p < .01). Children who developed peanut allergy by 5 years started to develop increasing sensitisation to linear sequential peanut epitopes from 2.5 years of age, suggesting that putative disease-modifying interventions should commence before 3 years. Data comparing clinical outcomes between children undergoing peanut immunotherapy from infancy suggest that younger children can consume higher portions of peanut without reaction on challenge whilst taking immunotherapy, have fewer side effects and are more likely to enjoy remission of PA. Peanut oral immunotherapy modulates T-cell populations in order to bring about hypo-responsiveness of allergy effector cells. Studies are now needed to characterise and compare different states of immunological tolerance. This will accelerate the design of interventions which can promote primary, secondary and tertiary levels of PA prevention across a range of age groups.

Engineering nanoparticle therapeutics for food allergy

Food allergy is a growing public health issue among children and adults that can lead to life-threatening anaphylaxis following allergen exposure. The criterion standard for disease management includes food avoidance and emergency epinephrine administration because current allergen-specific immunotherapy treatments are limited by adverse events and unsustained desensitization. A promising approach to remedy these shortcomings is the use of nanoparticle-based therapies that disrupt disease-driving immune mechanisms and induce more sustained tolerogenic immune pathways. The pathophysiology of food allergy includes multifaceted interactions between effector immune cells, including lymphocytes, antigen-presenting cells, mast cells, and basophils, mainly characterized by a TH2 cell response. Regulatory T cells, TH1 cell responses, and suppression of other major allergic effector cells have been found to be major drivers of beneficial outcomes in these nanoparticle therapies. Engineered nanoparticle formulations that have shown efficacy at reducing allergic responses and revealed new mechanisms of tolerance include polymeric-, lipid-, and emulsion-based nanotherapeutics. This review highlights the recent engineering design of these nanoparticles, the mechanisms induced by them, and their future potential therapeutic targets.

Role of transient receptor potential vanilloid 4 channels in an ovalbumin-induced murine food allergic model

The prevalence of food allergy (FA) has increased worldwide but an effective therapeutic strategy has not been established. Transient receptor potential vanilloid 4 (TRPV4), a mechanosensitive nonselective cation channel, is mainly expressed in the epithelium of various organs. The present study investigated the role of TRPV4 in the pathogenesis of an ovalbumin (OVA)-induced FA model in mice. Wild-type (WT) and TRPV4-deficient (TRPV4KO) mice were sensitized and challenged by OVA to establish FA model. Intestinal tissue samples were processed for biochemical, molecular, and image analyses. Intestinal permeability and antigen uptake assay were conducted using FITC-dextran and OVA-FITC, respectively. TRPV4 was expressed in the colonic epithelium in normal and OVA-treated WT mice. Repeated oral administration of OVA to mice induced systemic allergic symptoms, diarrhea, upregulation of T helper 2 cytokines, OVA-specific immunoglobulin, and FA-related inflammatory cells. These responses were significantly augmented in TRPV4KO mice compared with WT mice. After the induction of FA, the intestinal permeability was significantly increased in TRPV4KO mice compared with WT mice. The expressions of the tight junction protein occludin and adherence junction protein E-cadherin in the colon were significantly lower in TRPV4KO mice compared with WT mice under normal and FA conditions. In addition, the uptake of OVA by CD11c-positive cells was significantly increased in TRPV4KO mice compared with WT mice under FA conditions. These results suggest that epithelial TRPV4 protects against OVA-induced FA symptoms by suppressing the penetration of allergens by maintaining epithelial barrier functions.

Involvement and repair of epithelial barrier dysfunction in allergic diseases

The epithelial barrier serves as a critical defense mechanism separating the human body from the external environment, fulfilling both physical and immune functions. This barrier plays a pivotal role in shielding the body from environmental risk factors such as allergens, pathogens, and pollutants. However, since the 19th century, the escalating threats posed by environmental pollution, global warming, heightened usage of industrial chemical products, and alterations in biodiversity have contributed to a noteworthy surge in allergic disease incidences. Notably, allergic diseases frequently exhibit dysfunction in the epithelial barrier. The proposed epithelial barrier hypothesis introduces a novel avenue for the prevention and treatment of allergic diseases. Despite increased attention to the role of barrier dysfunction in allergic disease development, numerous questions persist regarding the mechanisms underlying the disruption of normal barrier function. Consequently, this review aims to provide a comprehensive overview of the epithelial barrier's role in allergic diseases, encompassing influencing factors, assessment techniques, and repair methodologies. By doing so, it seeks to present innovative strategies for the prevention and treatment of allergic diseases.

Lactobacillus paracasei AH2 isolated from Chinese sourdough alleviated gluten-induced food allergy through modulating gut microbiota and promoting short-chain fatty acid accumulation in a BALB/c mouse model

BACKGROUND

A large number of people worldwide suffer from gluten-induced food allergy. As investigated in our previous research, Lactobacillus paracasei AH2 isolated from traditionally homemade sourdough in Anhui province of China showed the potential to reduce the immune reactivity of wheat protein by in vitro evaluation. However, whether L. paracasei AH2 has a role in alleviating wheat allergy in an in vivo model and its underlying mechanisms have not been elucidated.

RESULTS

In this study, the alleviative effects of L. paracasei AH2 on gluten-induced allergic response were evaluated. Compared with a gluten-allergic mouse, L. paracasei AH2 suppressed anaphylaxis symptoms, gluten-specific immunoglobulin E, histamine and interleukin-4. Moreover, L. paracasei AH2 attenuated splenomegaly and induced Th1 or Treg cell differentiation to modulate the Th1/Th2 immune balance toward Th1 polarization. Short-chain fatty acid (SCFA) levels were enhanced after L. paracasei AH2 supplementation, contributing to allergy relief as well as reducing the pH of colonic contents. The α and β diversities of the gut microbiota were modulated by L. paracasei AH2 with increased relative abundance of Lacticaseibacillus and SCFA producers (Faecalibaculum, Alloprevotella and Bacteroides genera), as well as decreased unfavorable Lachnospiraceae_NK4A136_group and Alistipes. Additionally, L. paracasei AH2 protected the intestinal barrier function by upregulating tight junctions and improved the antioxidant activities in serum.

CONCLUSION

Our findings indicate that L. paracasei AH2 could act as a potential probiotic for relieving wheat allergy by modulating the gut microbiota and elevating SCFA levels. © 2023 Society of Chemical Industry.

Lateral Flow Immunochromatographic Assay for Competitive Detection of Crustacean Allergen Tropomyosin Using Phage-Displayed Shark Single-Domain Antibody

The common food allergy crustacean tropomyosin (TM) poses a significant food safety challenge, which requires rapid and sensitive methods for screening TM in food. Herein, the variable new antigen receptor (VNAR) single-domain antibodies specific for the crustacean TM were isolated from a naïve phage-displayed shark VNAR library. Subsequently, a lateral flow immunochromatographic assay (LFIA) based on the gold nanoparticle-labeled phage-displayed shark VNAR (AuNPs@PSV) probe was developed for the detection of TM in food. The AuNPs@PSV-LFIA took 15 min for one test and had a visual limit of detection (vLOD) of 0.1 μg/mL and an instrumental LOD of 0.02 μg/mL. Good selectivity, accuracy, precision, and stability were confirmed for the AuNPs@PSV-LFIA. Moreover, the test results of 21 commercially available food products consisted of the allergen labels and were validated by a commercial ELISA kit. Therefore, this work demonstrated the great potential of VNAR for detecting TM in food by LFIA.

A systematic two-sample and bidirectional MR process highlights a unidirectional genetic causal effect of allergic diseases on COVID-19 infection/severity

BACKGROUND

Allergic diseases (ADs) such as asthma are presumed risk factors for COVID-19 infection. However, recent observational studies suggest that the assumed correlation contradicts each other. We therefore systematically investigated the genetic causal correlations between various ADs and COVID-19 infection/severity.

METHODS

We performed a two-sample, bidirectional Mendelian randomization (MR) study for five types of ADs and the latest round of COVID-19 GWAS meta-analysis datasets (critically ill, hospitalized, and infection cases). We also further validated the significant causal correlations and elucidated the potential underlying molecular mechanisms.

RESULTS

With the most suitable MR method, asthma consistently demonstrated causal protective effects on critically ill and hospitalized COVID-19 cases (OR < 0.93, p < 2.01 × 10-2), which were further confirmed by another validated GWAS dataset (OR < 0.92, p < 4.22 × 10-3). In addition, our MR analyses also observed significant causal correlations of food allergies such as shrimp allergy with the risk of COVID-19 infection/severity. However, we did not find any significant causal effect of COVID-19 phenotypes on the risk of ADs. Regarding the underlying molecular mechanisms, not only multiple immune-related cells such as CD4+ T, CD8+ T and the ratio of CD4+/CD8+ T cells showed significant causal effects on COVID-19 phenotypes and various ADs, the hematology traits including monocytes were also significantly correlated with them. Conversely, various ADs such as asthma and shrimp allergy may be causally correlated with COVID-19 infection/severity by affecting multiple hematological traits and immune-related cells.

CONCLUSIONS

Our systematic and bidirectional MR analyses suggest a unidirectional causal effect of various ADs, particularly of asthma on COVID-19 infection/severity, but the reverse is not true. The potential underlying molecular mechanisms of the causal effects call for more attention to clinical monitoring of hematological cells/traits and may be beneficial in developing effective therapeutic strategies for allergic patients following infection with COVID-19.

Retinoic acid signaling in development and differentiation commitment and its regulatory topology

Retinoic acid (RA), the derivative of vitamin A/retinol, is a signaling molecule with important implications in health and disease. It is a well-known developmental morphogen that functions mainly through the transcriptional activity of nuclear RA receptors (RARs) and, uncommonly, through other nuclear receptors, including peroxisome proliferator-activated receptors. Intracellular RA is under spatiotemporally fine-tuned regulation by synthesis and degradation processes catalyzed by retinaldehyde dehydrogenases and P450 family enzymes, respectively. In addition to dictating the transcription architecture, RA also impinges on cell functioning through non-genomic mechanisms independent of RAR transcriptional activity. Although RA-based differentiation therapy has achieved impressive success in the treatment of hematologic malignancies, RA also has pro-tumor activity. Here, we highlight the relevance of RA signaling in cell-fate determination, neurogenesis, visual function, inflammatory responses and gametogenesis commitment. Genetic and post-translational modifications of RAR are also discussed. A better understanding of RA signaling will foster the development of precision medicine to improve the defects caused by deregulated RA signaling.

[Differential diagnosis in food allergy]

It is important to establish the differential diagnosis of food allergy with other disorders, for example: toxic reactions that occur in any person exposed to a sufficient amount of some allergen, and non-toxic reactions that depend on individual susceptibility (food allergy or intolerance). The differential diagnosis is decisive to establish the appropriate treatment. Food intolerance involves adverse reactions to foods without any immunological response involved, and commonly manifests with gastrointestinal symptoms (malaise, abdominal pain or diarrhea). Food allergy is an exaggerated reaction of the immune system, often mediated by IgE, that can trigger serious symptoms (hives, inflammation, respiratory distress, even anaphylaxis). The complex thing is because the symptoms sometimes overlap. To establish an accurate diagnosis, exhaustive clinical evaluation, laboratory tests and, in some cases, controlled provocation tests are required. It is important to understand these distinctions, because treatment and management vary significantly. Food intolerance involves the elimination or reduction of the food that triggers the allergic reaction and requires rigorous measures (complete avoidance of the allergen and availability of epinephrine in cases of severe reactions).

[Physiopathology of food allergies]

Food allergy is an adverse reaction to certain foods that have demonstrated "immunological mechanisms"; therefore, this term covers both food allergies mediated or not by immunoglobulin E (IgE). The common pathophysiological mechanism among forms of allergy to foods mediated or not by IgE is found in the failure of clinical and immunological tolerance towards that food. The induction and maintenance of immunological tolerance depends on the active generation of regulatory T cells specific for food antigens. This process is influenced by genetic factors (FOXP3 genes) and epigenetic factors conditioned by the environment (diet, microbiota, and their products). Since the intestinal microbiome can normally promote oral tolerance, current evidence suggests that perturbations of the microbiome may correlate, or even predispose, with food allergy. Understanding the pathogenic mechanism underlying IgE-mediated food allergies allows the implementation of measures aimed at restoring clinical and immunological tolerance. Knowledge of the mechanisms of food allergy will improve the outlook for patients with more severe immediate food allergies and anaphylaxis, as well as those who have comorbidities (atopic dermatitis, eosinophilic esophagitis and EGEIDs).

[Non-IgE-mediated food allergy]

Food allergy is an immune response to proteins in food. It usually affects 8% of children and 2% of adults in Western countries. Non-IgE-mediated food allergy mainly affects the gastrointestinal tract. Gastrointestinal food allergies are classified, by their underlying pathogenesis, as: IgE-mediated, non-IgE-mediated, or mixed. The symptoms of patients with food protein-induced allergic proctocolitis originate from local inflammation of the distal colon, which causes hematochezia in neonates. It can affect the entire gastrointestinal tract and cause symptoms of intractable emesis, with subsequent metabolic disorders and hypovolemic shock. Food protein-induced enterocolitis syndrome is a non-IgE-mediated allergy that usually appears in childhood, with prolonged repetitive vomiting, starting 1 to 4 hours after ingestion of food. The manifestation in adults is usually triggered by the consumption of shellfish. Atopic diseases affect 40-60% of patients with food protein- induced enterocolitis syndrome, including 40-50% of those with food protein-induced enteropathy and proctocolitis. Probiotics (Lactobacillus GG) can alleviate the symptoms of allergic proctocolitis induced by food proteins, by altering the composition of the intestinal microbiota. Fecal microbiota transplantation (FMT) can change intestinal microecology efficiently compared to food or probiotics.

2'-Fucosyllactose alleviates OVA-induced food allergy in mice by ameliorating intestinal microecology and regulating the imbalance of Th2/Th1 proportion

Food allergy (FA) has become a prominent problem in public health. 2'-Fucosyllactose (2'-FL) was reported to alleviate FA symptoms; however, the regulatory mechanism is still unclear. This study evaluated the 2'-FL antiallergic potential in an ovalbumin (OVA)-sensitized mouse model and explored the systemic effects of 2'-FL on gut microecology and the intestinal immune barrier. The results showed that 2'-FL alleviated allergy symptoms, decreased serum allergic indicator levels, enhanced the intestinal barrier, and attenuated low-grade inflammation. The up-regulation of G protein-coupled receptors (GPRs) was associated with higher levels of short-chain fatty acids (SCFAs) in 2'-FL intervention mice. 2'-FL also improved the intestinal microbiota diversity and increased the abundance of Akkermansia, Lachnospiraceae UCG-006, and Ruminococcaceae while suppressing Muribaculaceae, Desulfovibrionaceae, and Erysipelotrichaceae. Additionally, 2'-FL ameliorated the imbalance of Th2/Th1, mainly by decreasing Th2-type immune response and enhanced CD4 + Foxp3 + Treg immunoreaction. These results suggest that 2'-FL restores intestinal barrier defects, gut microbiota disorder, and immune impairment while alleviating ovalbumin-induced allergic symptoms in FA mice.

Prospects for developing allergen-depleted food crops

In addition to the challenge of meeting global demand for food production, there are increasing concerns about food safety and the need to protect consumer health from the negative effects of foodborne allergies. Certain bio-molecules (usually proteins) present in food can act as allergens that trigger unusual immunological reactions, with potentially life-threatening consequences. The relentless working lifestyles of the modern era often incorporate poor eating habits that include readymade prepackaged and processed foods, which contain additives such as peanuts, tree nuts, wheat, and soy-based products, rather than traditional home cooking. Of the predominant allergenic foods (soybean, wheat, fish, peanut, shellfish, tree nuts, eggs, and milk), peanuts (Arachis hypogaea) are the best characterized source of allergens, followed by tree nuts (Juglans regia, Prunus amygdalus, Corylus avellana, Carya illinoinensis, Anacardium occidentale, Pistacia vera, Bertholletia excels), wheat (Triticum aestivum), soybeans (Glycine max), and kidney beans (Phaseolus vulgaris). The prevalence of food allergies has risen significantly in recent years including chance of accidental exposure to such foods. In contrast, the standards of detection, diagnosis, and cure have not kept pace and unfortunately are often suboptimal. In this review, we mainly focus on the prevalence of allergies associated with peanut, tree nuts, wheat, soybean, and kidney bean, highlighting their physiological properties and functions as well as considering research directions for tailoring allergen gene expression. In particular, we discuss how recent advances in molecular breeding, genetic engineering, and genome editing can be used to develop potential low allergen food crops that protect consumer health.

Study protocol to investigate the efficacy of confocal laser endomicroscopy-based selective single-elimination diet over standard fivefold elimination diet in patients with endomicroscopically proven food intolerance: app-assisted, monocentric, double-blind, randomised and controlled trial in Germany

INTRODUCTION

Imprecise nutritional recommendations due to a lack of diagnostic test accuracy are a frequent problem for individuals with adverse reactions to foods but no precise diagnosis. Consequently, patients follow very broad and strict elimination diets to avoid uncontrolled symptoms such as diarrhoea and abdominal pain. Dietary limitations and the uncertainty of developing gastrointestinal symptoms after the inadvertent ingestion of food have been demonstrated to reduce the quality of life (QoL) of affected individuals and subsequently might increase the risk of malnutrition and intestinal dysbiosis. This trial aims to investigate the effects of a tailored diet based on the confocal laser endoscopy (CLE) examination result to limit the side effects of unspecific and broad elimination diets and to increase the patient's QoL.

METHODS AND ANALYSIS

The study is designed as a prospective, double-blind, monocentric, randomised and controlled trial conducted at the University Hospital of Schleswig-Holstein, Campus Lübeck, Germany. One hundred seventy-two patients with non-IgE-related food allergies and positive CLE results will be randomised to either a tailored diet or a standard fivefold elimination diet. The primary endpoints are the difference between the end and the start of the intervention in health-related QoL and the sum score of the severity of symptoms after 12 weeks. Key secondary endpoints are changes in the severity of symptoms, further QoL measurements, self-assessed state of health and number of days with a pathologically altered stool. Microbiome diversity and metabolome of stool, urine and blood will also be investigated. Safety endpoints are body composition, body mass index and adverse events.

ETHICS AND DISSEMINATION

The study protocol was accepted by the ethical committee of the University of Lübeck (AZ: 22-111) on 4 May2022. Results of the study will be published in peer-reviewed journals and presented at scientific meetings.

TRIAL REGISTRATION NUMBER

German Clinical Trials Register (DRKS00029323).

Regulatory T cells in allergic inflammation

Regulatory T (Treg) cells maintain immune tolerance to allergens at the environmental interfaces in the airways, skin and gut, marshalling in the process distinct immune regulatory circuits operative in the respective tissues. Treg cells are coordinately mobilized with allergic effector mechanisms in the context of a tissue-protective allergic inflammatory response against parasites, toxins and potentially harmful allergens, serving to both limit the inflammation and promote local tissue repair. Allergic diseases are associated with subverted Treg cell responses whereby a chronic allergic inflammatory environment can skew Treg cells toward pathogenic phenotypes that both perpetuate and aggravate disease. Interruption of Treg cell subversion in chronic allergic inflammatory conditions may thus provide novel therapeutic strategies by re-establishing effective immune regulation.

The chemistry of gut microbiome-derived lipopolysaccharides impacts on the occurrence of food allergy in the pediatric age

Introduction: Food allergy (FA) in children is a major health concern. A better definition of the pathogenesis of the disease could facilitate effective preventive and therapeutic measures. Gut microbiome alterations could modulate the occurrence of FA, although the mechanisms involved in this phenomenon are poorly characterized. Gut bacteria release signaling byproducts from their cell wall, such as lipopolysaccharides (LPSs), which can act locally and systemically, modulating the immune system function. Methods: In the current study gut microbiome-derived LPS isolated from fecal samples of FA and healthy children was chemically characterized providing insights into the carbohydrate and lipid composition as well as into the LPS macromolecular nature. In addition, by means of a chemical/MALDI-TOF MS and MS/MS approach we elucidated the gut microbiome-derived lipid A mass spectral profile directly on fecal samples. Finally, we evaluated the pro-allergic and pro-tolerogenic potential of these fecal LPS and lipid A by harnessing peripheral blood mononuclear cells from healthy donors. Results: By analyzing fecal samples, we have identified different gut microbiome-derived LPS chemical features comparing FA children and healthy controls. We also have provided evidence on a different immunoregulatory action elicited by LPS on peripheral blood mononuclear cells collected from healthy donors suggesting that LPS from healthy individuals could be able to protect against the occurrence of FA, while LPS from children affected by FA could promote the allergic response. Discussion: Altogether these data highlight the relevance of gut microbiome-derived LPSs as potential biomarkers for FA and as a target of intervention to limit the disease burden.

Immune signatures predicting the clinical outcome of peanut oral immunotherapy: where we stand

Peanut allergy is a growing health concern that can cause mild to severe anaphylaxis as well as reduced quality of life in patients and their families. Oral immunotherapy is an important therapeutic intervention that aims to reshape the immune system toward a higher threshold dose reactivity and sustained unresponsiveness in some patients. From an immunological point of view, young patients, especially those under 3 years old, seem to have the best chance for therapy success. To date, surrogate markers for therapy duration and response are evasive. We provide a comprehensive overview of the current literature state regarding immune signatures evolving over the course of oral immunotherapy as well as baseline immune conditions prior to the initiation of treatment. Although research comparing clinical and immune traits in the first years of life vs. later stages across different age groups is limited, promising insights are available on immunological endotypes among peanut-allergic patients. The available data call for continued research to fill in gaps in knowledge, possibly in an integrated manner, to design novel precision health approaches for advanced therapeutic interventions in peanut allergy.

Effects of hazelnut protein isolate-induced food allergy on the gut microenvironment in a BALB/c mouse model

Hazelnuts are reported as among the nuts that cause severe allergic reactions. However, few systematic studies exist on the changes in the gut microenvironment following hazelnut allergy. This study focused on the effects of hazelnut allergy on the duodenum, jejunum, ileum and colon microenvironment in vivo. We established a hazelnut protein isolate (HPI)-allergic mouse model, which was distinguished by the visible allergy symptoms, dropped temperatures and enhanced allergic inflammatory factor levels in serum, such as HPI-specific immunoglobulin E (sIgE), sIgG2a, interleukin-4, histamine, mouse mast cell protease-1, TNF-α, monocyte chemotactic protein-1 and lipopolysaccharide. For HPI sensitized mice, aggravated mast cell degranulation, severe morphologic damage and inflammatory cell infiltration were observed in the duodenum, jejunum, ileum, and colon, while goblet cell numbers were reduced in the duodenum, jejunum and ileum. Secretory IgA of the jejunum and tight junctions of the duodenum and jejunum were decreased significantly after HPI sensitization. There was no remarkable difference in the pH values of small intestinal contents, but the pH values of colonic contents were elevated, which was due to the decreased short-chain fatty acids (mainly acetate, propionate and butyrate) in the colon. The antioxidant capacity of both large and small intestinal contents declined after HPI sensitization, as evidenced by the increased malondialdehyde and decreased superoxide dismutase activity. HPI sensitization induced gut microbiota dysbiosis with decreased α diversity and altered β diversity in colonic contents. Spearman correlation analysis indicated that the increased characteristic genera, namely Bacteroides, Lactobacillus, Alloprevotella, Erysipelatoclostridium, Parabacteroides, and Helicobacter, played potentially synergistic roles in promoting allergy and gut microenvironment dysregulation.

A comprehensive review on glycation and its potential application to reduce food allergenicity

Food allergens are a major concern for individuals who are susceptible to food allergies and may experience various health issues due to allergens in their food. Most allergenic foods are subjected to heat treatment before being consumed. However, thermal processing and prolonged storage can cause glycation reactions to occur in food. The glycation reaction is a common processing method requiring no special chemicals or equipment. It may affect the allergenicity of proteins by altering the structure of the epitope, revealing hidden epitopes, concealing linear epitopes, or creating new ones. Changes in food allergenicity following glycation processing depend on several factors, including the allergen's characteristics, processing parameters, and matrix, and are therefore hard to predict. This review examines how glycation reactions affect the allergenicity of different allergen groups in allergenic foods.

Immunotoxicity of engineered nanomaterials and their role in asthma

The toxicity of engineered nanomaterials (ENMs) in vivo and in vitro has formed the basis of most studies. However, the toxicity of ENMs, particularly on the immune system, i.e. immunotoxicity, and their role in manipulating it, are less known. This review addresses the initiation or exacerbation as well as the attenuation of allergic asthma by a variety of ENMs and how they may be used in drug delivery to enhance the treatment of asthma. This review also highlights a few research gaps in the study of the immunotoxicity of ENMs, for example, the potential drawbacks of assays used in immunotoxicity assays; the potential role of hormesis during dosing of ENMs; and the variables that result in discrepancies among different studies, such as the physicochemical properties of ENMs, differences in asthmatic animal models, and different routes of administration.

The interplay between innate lymphoid cells and microbiota

Innate lymphoid cells (ILCs) are mainly resident in mucosal tissues such as gastrointestinal tract and respiratory tract, so they are closely linked to the microbiota. ILCs can protect commensals to maintain homeostasis and increase resistance to pathogens. Moreover, ILCs also play an early role in defense against a variety of pathogenic microorganisms including pathogenic bacteria, viruses, fungi and parasites, before the intervention of adaptive immune system. Due to the lack of adaptive antigen receptors expressed on T cells and B cells, ILCs need to use other means to sense the signals of microbiota and play a role in corresponding regulation. In this review, we focus on and summarize three major mechanisms used in the interaction between ILCs and microbiota: the mediation of accessory cells represented by dendritic cells; the metabolic pathways of microbiota or diet; the participation of adaptive immune cells.

Murine model identifies tropomyosin as IgE cross-reactive protein between house dust mite and coho salmon that possibly contributes to the development of salmon allergy

Background

Recently, we have developed a method to identify IgE cross-reactive allergens. However, the mechanism by which IgE cross-reactive allergens cause food allergy is not yet fully understood how. In this study, we aimed to understand the underlying pathogenesis by identifying food allergens that cross-react with house dust mite allergens in a murine model.

Material and methods

Allergenic protein microarray analysis was conducted using serum from mice intraperitoneally injected with Dermatophagoides pteronyssinus (Der p) extract plus alum or alum alone as controls. Der p, Dermatophagoides farinae (Der f), coho salmon extract-sensitized and control mice were analyzed. Serum levels of IgE against Der p, Der f, coho salmon extract, protein fractions of coho salmon extract separated by ammonium sulfate precipitation and anion exchange chromatography, and recombinant coho salmon tropomyosin or actin were measured by an enzyme-linked immunosorbent assay. A murine model of cutaneous anaphylaxis or oral allergy syndrome (OAS) was established in Der p extract-sensitized mice stimulated with coho salmon extract, tropomyosin, or actin.

Results

Protein microarray analysis showed that coho salmon-derived proteins were highly bound to serum IgE in Der p extract-sensitized mice. Serum IgE from Der p or Der f extract-sensitized mice was bound to coho salmon extract, whereas serum IgE from coho salmon extract-sensitized mice was bound to Der p or Der f extract. Analysis of the murine model showed that cutaneous anaphylaxis and oral allergic reaction were evident in Der p extract-sensitized mice stimulated by coho salmon extract. Serum IgE from Der p or Der f extract-sensitized mice was bound strongly to protein fractions separated by anion exchange chromatography of coho salmon proteins precipitated with 50% ammonium sulfate, which massively contained the approximately 38 kDa protein. We found that serum IgE from Der p extract-sensitized mice was bound to recombinant coho salmon tropomyosin. Der p extract-sensitized mice exhibited cutaneous anaphylaxis in response to coho salmon tropomyosin.

Conclusion

Our results showed IgE cross-reactivity of tropomyosin between Dermatophagoides and coho salmon which illustrates salmon allergy following sensitization with the house dust mite Dermatophagoides. Our method for identifying IgE cross-reactive allergens will help understand the underlying mechanisms of food allergies.

Bivalent structure of a TNFR2-selective and agonistic TNF-α mutein Fc-fusion protein enhances the expansion activity of regulatory T cells

Recently, TNF receptor type 2 (TNFR2) signaling was found to be involved in the proliferation and activation of regulatory T cells (Tregs), a subpopulation of lymphocytes that suppress immune responses. Tregs mediate peripheral immune tolerance, and the disruption of their functions causes autoimmune diseases or allergy. Therefore, cell expanders or regulators of Tregs that control immunosuppressive activity can be used to treat these diseases. We focused on TNFR2, which is preferentially expressed on Tregs, and created tumor necrosis factor-α (TNF-α) muteins that selectively activate TNFR2 signaling in mice and humans, termed R2agoTNF and R2-7, respectively. In this study, we attempted to optimize the structure of muteins to enhance their TNFR2 agonistic activity and stability in vivo by IgG-Fc fusion following single-chain homo-trimerization. The fusion protein, scR2agoTNF-Fc, enhanced the expansion of CD4+CD25+ Tregs and CD4+Foxp3+ Tregs and contributed to their immunosuppressive activity ex vivo and in vivo in mice. The prophylactic administration of scR2agoTNF-Fc suppressed inflammation in contact hypersensitivity and arthritis mouse models. Furthermore, scR2-7-Fc preferentially expanded Tregs in human peripheral blood mononuclear cells via TNFR2. These TNFR2 agonist-Fc fusion proteins, which have bivalent structures, are novel Treg expanders.

Maternal Dietary Vitamin D Intake during Pregnancy Is Associated with Allergic Disease Symptoms in Children at 3 Years Old: The Japan Environment and Children's Study

INTRODUCTION

Vitamin D plays an important role in the immune system, and postnatal vitamin D insufficiency is one of the risk factors for the development of allergic disease. However, the effects of women's vitamin D intake during pregnancy on the prevalence of allergic disease in their children remain controversial.

METHODS

From the Japan Environment and Children's Study, an ongoing nationwide birth cohort study, we obtained information on maternal dietary vitamin D intake determined using a food frequency questionnaire and parent-reported allergic disease symptoms based on the ISAAC questionnaire in children at 3 years of age.

RESULTS

From the full dataset of 103,060 pregnancies, we analyzed complete data for 73,309 mother-child pairs. The prevalence of current wheeze, current rhinitis, current rhino-conjunctivitis, current eczema, ever asthma, ever pollinosis, and ever atopic dermatitis in the children was 17.2%, 29.7%, 3.8%, 15.2%, 9.6%, 3.7%, and 11.0%, respectively. The ORs for current rhinitis were significantly lower in the 3rd, 4th, and 5th quintiles than in the 1st quintile after adjustment for various covariates and showed a linear association. The ORs for ever pollinosis were significantly lower in the 2nd, 3rd, and 4th quintiles than in the 1st quintile, showing a U-shaped curve. There was no clear association between mothers' dietary vitamin D intake and symptoms of asthma or atopic dermatitis in their 3-year-old children.

CONCLUSION

Maternal dietary vitamin D intake during pregnancy is associated with the ORs for nasal allergies in children at the age of 3 years. Further studies are warranted to evaluate the appropriate intake dose of vitamin D for pregnant women to prevent the development of nasal allergies in their children.

The early-phase transcriptome and the clinical efficacy analysis in three modes of subcutaneous immunotherapy for allergic rhinitis

Background

Allergen immunotherapy is the only etiological treatment for allergic rhinitis.

Objective

To analyze the efficacy, safety, and mechanism of subcutaneous immunotherapy (SCIT).

Methods

The efficacy, safety, and serum immunological changes of 3 modes of subcutaneous immunotherapy were compared. Peripheral blood mononuclear cells (PBMC) transcriptome changes were obtained on the Illumina sequencing platforms. We confirmed differentially expressed genes (DEGs) by quantitative real-time polymerase chain reaction (PCR). The DEGs were analyzed by gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and protein-protein interaction (PPI) networks. The correlation between the common DEGs and clinical indicators was analyzed by Origin 2022.

Results

The 3 SCITs were all effective after 1 year. The Combined Symptom and Medication Score (CSMS) and Visual Analog Score (VAS) in rush immunotherapy (RIT) are lowest after 24 and 48 weeks of treatment among the 3 groups. After treatment, the levels of sIgE, sIgE/tIgE, Th2 cytokines, Th17 cytokines, and percentage of peripheral eosinophils (EOS%) decreased significantly (P＜0.05), while the levels of Th1 type cytokines did not change significantly. Transcriptome analysis identified 24, 24, and 91 DEGs at W3 and 42, 52, 175 DEGs at W7 in conventional immunotherapy (CIT), cluster immunotherapy (CLIT), and RIT groups, respectively. The pathways and functions involved in SCIT include secretion of Th1/2 cytokines, immune cell differentiation. Unlike CIT and CLIT, DEGs are also involved in T cell tolerance induction, T cell anergy, and lymphocyte anergy in RIT. CXCR1, CXCR2, and IER3 had a specific effect on reflecting the improvement of symptoms in allergic rhinitis patients with SCIT.

Conclusion

The clinical efficacy of RIT appeared earlier than CIT and CLIT. Clinicians can use the highly conserved gene expression profile to evaluate responses to immunotherapy.

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.

Biologicals in IgE-mediated food allergy

PURPOSE OF REVIEW

A better understanding of the most recent scientific literature in the use of biological therapy in the treatment of patients with IgE-mediated food allergy.

RECENT FINDINGS

A systematic review and meta-analysis demonstrated safety and effectiveness of omalizumab in the treatment of food allergy. The findings support the potential use of omalizumab as a monotherapy or as an adjunct to oral immunotherapy in IgE-mediated cow's milk allergy. The potential use of other biologics in the management of food allergy is subject of speculation.

SUMMARY

Different biological therapies are under evaluation for food allergic patients. The advance in literature will guide for a personalized treatment in the near future. However, additional research is needed to better understand the best candidate for each treatment, the optimal dose and timing.

Degranulation of Mast Cells as a Target for Drug Development

Mast cells act as key effector cells of inflammatory responses through degranulation. Mast cell degranulation is induced by the activation of cell surface receptors, such as FcεRI, MRGPRX2/B2, and P2RX7. Each receptor, except FcεRI, varies in its expression pattern depending on the tissue, which contributes to their differing involvement in inflammatory responses depending on the site of occurrence. Focusing on the mechanism of allergic inflammatory responses by mast cells, this review will describe newly identified mast cell receptors in terms of their involvement in degranulation induction and patterns of tissue-specific expression. In addition, new drugs targeting mast cell degranulation for the treatment of allergy-related diseases will be introduced.

Trained innate immunity, epigenetics, and food allergy

In recent years the increased incidence of food allergy in Western culture has been associated with environmental factors and an inappropriate immune phenotype. While the adaptive immune changes in food allergy development and progression have been well-characterized, an increase in innate cell frequency and activation status has also recently received greater attention. Early in prenatal and neonatal development of human immunity there is a reliance on epigenetic and metabolic changes that stem from environmental factors, which are critical in training the immune outcomes. In the present review, we discuss how trained immunity is regulated by epigenetic, microbial and metabolic factors, and how these factors and their impact on innate immunity have been linked to the development of food allergy. We further summarize current efforts to use probiotics as a potential therapeutic approach to reverse the epigenetic and metabolic signatures and prevent the development of severe anaphylactic food allergy, as well as the potential use of trained immunity as a diagnostic and management strategy. Finally, trained immunity is presented as one of the mechanisms of action of allergen-specific immunotherapy to promote tolerogenic responses in allergic individuals.

Staphylococcus aureus δ-toxin present on skin promotes the development of food allergy in a murine model

Background

Patients with food allergy often suffer from atopic dermatitis, in which Staphylococcus aureus colonization is frequently observed. Staphylococcus aureus δ-toxin activates mast cells and promotes T helper 2 type skin inflammation in the tape-stripped murine skin. However, the physiological effects of δ-toxin present on the steady-state skin remain unknown. We aimed to investigate whether δ-toxin present on the steady-state skin impacts the development of food allergy.

Material and methods

The non-tape-stripped skins of wild-type, Kit^W-sh/W-sh, or ST2-deficient mice were treated with ovalbumin (OVA) with or without δ-toxin before intragastric administration of OVA. The frequency of diarrhea, numbers of jejunum or skin mast cells, and serum levels of OVA-specific IgE were measured. Conventional dendritic cell 2 (cDC2) in skin and lymph nodes (LN) were analyzed. The cytokine levels in the skin tissues or culture supernatants of δ-toxin-stimulated murine keratinocytes were measured. Anti-IL-1α antibody-pretreated mice were analyzed.

Results

Stimulation with δ-toxin induced the release of IL-1α, but not IL-33, in murine keratinocytes. Epicutaneous treatment with OVA and δ-toxin induced the local production of IL-1α. This treatment induced the translocation of OVA-loaded cDC2 from skin to draining LN and OVA-specific IgE production, independently of mast cells and ST2. This resulted in OVA-administered food allergic responses. In these models, pretreatment with anti-IL-1α antibody inhibited the cDC2 activation and OVA-specific IgE production, thereby dampening food allergic responses.

Conclusion

Even without tape stripping, δ-toxin present on skin enhances epicutaneous sensitization to food allergen in an IL-1α-dependent manner, thereby promoting the development of food allergy.

Advanced Proteomic and Bioinformatic Tools for Predictive Analysis of Allergens in Novel Foods

In recent years, novel food is becoming an emerging trend increasingly more demanding in developed countries. Food proteins from vegetables (pulses, legumes, cereals), fungi, bacteria and insects are being researched to introduce them in meat alternatives, beverages, baked products and others. One of the most complex challenges for introducing novel foods on the market is to ensure food safety. New alimentary scenarios drive the detection of novel allergens that need to be identified and quantified with the aim of appropriate labelling. Allergenic reactions are mostly caused by proteins of great abundance in foods, most frequently of small molecular mass, glycosylated, water-soluble and with high stability to proteolysis. The most relevant plant and animal food allergens, such as lipid transfer proteins, profilins, seed storage proteins, lactoglobulins, caseins, tropomyosins and parvalbumins from fruits, vegetables, nuts, milk, eggs, shellfish and fish, have been investigated. New methods for massive screening in search of potential allergens must be developed, particularly concerning protein databases and other online tools. Moreover, several bioinformatic tools based on sequence alignment, motif identification or 3-D structure predictions should be implemented as well. Finally, targeted proteomics will become a powerful technology for the quantification of these hazardous proteins. The ultimate objective is to build an effective and resilient surveillance network with this cutting-edge technology.

Analysis of Circulating Food Antigen-Specific T-Cells in Celiac Disease and Inflammatory Bowel Disease

To demonstrate and analyze the specific T-cell response following barrier disruption and antigen translocation, circulating food antigen-specific effector T-cells isolated from peripheral blood were analyzed in patients suffering from celiac disease (CeD) as well as inflammatory bowel disease (IBD). We applied the antigen-reactive T-cell enrichment (ARTE) technique allowing for phenotypical and functional flow cytometric analyses of rare nutritional antigen-specific T-cells, including the celiac disease-causing gliadin (gluten). For CeD, patient groups, including treatment-refractory cases, differ significantly from healthy controls. Even symptom-free patients on a gluten-free diet were distinguishable from healthy controls, without being previously challenged with gluten. Moreover, frequency and phenotype of nutritional antigen-specific T-cells of IBD patients directly correlated to the presence of small intestinal inflammation. Specifically, the frequency of antigen specific T-cells as well as pro-inflammatory cytokines was increased in patients with active CeD or Crohn's disease, respectively. These results suggest active small intestinal inflammation as key for the development of a peripheral food antigen-specific T-cell response in Crohn's disease and celiac disease.

International consensus statement on allergy and rhinology: Allergic rhinitis - 2023

BACKGROUND

In the 5 years that have passed since the publication of the 2018 International Consensus Statement on Allergy and Rhinology: Allergic Rhinitis (ICAR-Allergic Rhinitis 2018), the literature has expanded substantially. The ICAR-Allergic Rhinitis 2023 update presents 144 individual topics on allergic rhinitis (AR), expanded by over 40 topics from the 2018 document. Originally presented topics from 2018 have also been reviewed and updated. The executive summary highlights key evidence-based findings and recommendation from the full document.

METHODS

ICAR-Allergic Rhinitis 2023 employed established evidence-based review with recommendation (EBRR) methodology to individually evaluate each topic. Stepwise iterative peer review and consensus was performed for each topic. The final document was then collated and includes the results of this work.

RESULTS

ICAR-Allergic Rhinitis 2023 includes 10 major content areas and 144 individual topics related to AR. For a substantial proportion of topics included, an aggregate grade of evidence is presented, which is determined by collating the levels of evidence for each available study identified in the literature. For topics in which a diagnostic or therapeutic intervention is considered, a recommendation summary is presented, which considers the aggregate grade of evidence, benefit, harm, and cost.

CONCLUSION

The ICAR-Allergic Rhinitis 2023 update provides a comprehensive evaluation of AR and the currently available evidence. It is this evidence that contributes to our current knowledge base and recommendations for patient evaluation and treatment.

Evidence that High-Affinity IgE Can Develop in the Germinal Center in the Absence of an IgG1-Switched Intermediate

High-affinity allergen-specific IgE is essential for the severe allergic anaphylaxis response. High-affinity Abs are formed by successive rounds of selection of Ag-specific B cells in the germinal center (GC); however, several studies have shown that IgE+ GC B cells are impaired in their ability to undergo selection in the GC. A pathway, known as the "indirect switching pathway" for IgE, has been described whereby Ag-specific B cells initially switch to the IgG1 isotype and undergo affinity selection in the GC, with a secondary switch to the IgE isotype after affinity selection. In previous work, using a food allergy model in mice, we investigated how high-affinity IgE develops in the GC, but we did not test the indirect switching model. In this study, we analyzed the importance of the indirect switching pathway by constructing IgG1-cre Bcl6-fl/fl mice. In these mice, once B cells switch to IgG1, they delete Bcl6 and thus cannot enter or persist in the GC. When we tested IgG1-cre Bcl6-fl/fl mice with our food allergy model, we found that, as expected, IgG1 Abs had decreased affinity, but unexpectedly, the affinity of IgE for allergen was unchanged. IgG1-cre Bcl6-fl/fl mice underwent anaphylaxis in response to allergen, consistent with the formation of high-affinity IgE. Thus, in a food allergy response, high-affinity IgE can be efficiently formed in the absence of indirect switching to IgG1, either by direct selection of IgE+ GC B cells or indirect selection of IgM+ GC B cells that later switch to IgE.

Pathogenesis of allergic diseases and implications for therapeutic interventions

Allergic diseases such as allergic rhinitis (AR), allergic asthma (AAS), atopic dermatitis (AD), food allergy (FA), and eczema are systemic diseases caused by an impaired immune system. Accompanied by high recurrence rates, the steadily rising incidence rates of these diseases are attracting increasing attention. The pathogenesis of allergic diseases is complex and involves many factors, including maternal-fetal environment, living environment, genetics, epigenetics, and the body's immune status. The pathogenesis of allergic diseases exhibits a marked heterogeneity, with phenotype and endotype defining visible features and associated molecular mechanisms, respectively. With the rapid development of immunology, molecular biology, and biotechnology, many new biological drugs have been designed for the treatment of allergic diseases, including anti-immunoglobulin E (IgE), anti-interleukin (IL)-5, and anti-thymic stromal lymphopoietin (TSLP)/IL-4, to control symptoms. For doctors and scientists, it is becoming more and more important to understand the influencing factors, pathogenesis, and treatment progress of allergic diseases. This review aimed to assess the epidemiology, pathogenesis, and therapeutic interventions of allergic diseases, including AR, AAS, AD, and FA. We hope to help doctors and scientists understand allergic diseases systematically.