TCF1-LEF1 co-expression identifies a multipotent progenitor cell (TH2-MPP) across human allergic diseases.

Repetitive exposure to antigen in chronic infection and cancer drives T cell exhaustion, limiting adaptive immunity. In contrast, aberrant, sustained T cell responses can persist over decades in human allergic disease. To understand these divergent outcomes, we employed bioinformatic, immunophenotyping and functional approaches with human diseased tissues, identifying an abundant population of type 2 helper T (TH2) cells with co-expression of TCF7 and LEF1, and features of chronic activation. These cells, which we termed TH2-multipotent progenitors (TH2-MPP) could self-renew and differentiate into cytokine-producing effector cells, regulatory T (Treg) cells and follicular helper T (TFH) cells. Single-cell T-cell-receptor lineage tracing confirmed lineage relationships between TH2-MPP, TH2 effectors, Treg cells and TFH cells. TH2-MPP persisted despite in vivo IL-4 receptor blockade, while thymic stromal lymphopoietin (TSLP) drove selective expansion of progenitor cells and rendered them insensitive to glucocorticoid-induced apoptosis in vitro. Together, our data identify TH2-MPP as an aberrant T cell population with the potential to sustain type 2 inflammation and support the paradigm that chronic T cell responses can be coordinated over time by progenitor cells.

TCR sequencing paired with massively parallel 3' RNA-seq reveals clonotypic T cell signatures.

High-throughput 3' single-cell RNA-sequencing (scRNA-seq) allows cost-effective, detailed characterization of individual immune cells from tissues. Current techniques, however, are limited in their ability to elucidate essential immune cell features, including variable sequences of T cell antigen receptors (TCRs) that confer antigen specificity. Here, we present a strategy that enables simultaneous analysis of TCR sequences and corresponding full transcriptomes from 3'-barcoded scRNA-seq samples. This approach is compatible with common 3' scRNA-seq methods, and adaptable to processed samples post hoc. We applied the technique to identify transcriptional signatures associated with T cells sharing common TCRs from immunized mice and from patients with food allergy. We observed preferential phenotypes among subsets of expanded clonotypes, including type 2 helper CD4+ T cell (TH2) states associated with food allergy. These results demonstrate the utility of our method when studying diseases in which clonotype-driven responses are critical to understanding the underlying biology.

Omalizumab for the Treatment of Multiple Food Allergies.

BACKGROUND: Food allergies are common and are associated with substantial morbidity; the only approved treatment is oral immunotherapy for peanut allergy. METHODS: In this trial, we assessed whether omalizumab, a monoclonal anti-IgE antibody, would be effective and safe as monotherapy in patients with multiple food allergies. Persons 1 to 55 years of age who were allergic to peanuts and at least two other trial-specified foods (cashew, milk, egg, walnut, wheat, and hazelnut) were screened. Inclusion required a reaction to a food challenge of 100 mg or less of peanut protein and 300 mg or less of the two other foods. Participants were randomly assigned, in a 2:1 ratio, to receive omalizumab or placebo administered subcutaneously (with the dose based on weight and IgE levels) every 2 to 4 weeks for 16 to 20 weeks, after which the challenges were repeated. The primary end point was ingestion of peanut protein in a single dose of 600 mg or more without dose-limiting symptoms. The three key secondary end points were the consumption of cashew, of milk, and of egg in single doses of at least 1000 mg each without dose-limiting symptoms. The first 60 participants (59 of whom were children or adolescents) who completed this first stage were enrolled in a 24-week open-label extension. RESULTS: Of the 462 persons who were screened, 180 underwent randomization. The analysis population consisted of the 177 children and adolescents (1 to 17 years of age). A total of 79 of the 118 participants (67%) receiving omalizumab met the primary end-point criteria, as compared with 4 of the 59 participants (7%) receiving placebo (P<0.001). Results for the key secondary end points were consistent with those of the primary end point (cashew, 41% vs. 3%; milk, 66% vs. 10%; egg, 67% vs. 0%; P<0.001 for all comparisons). Safety end points did not differ between the groups, aside from more injection-site reactions in the omalizumab group. CONCLUSIONS: In persons as young as 1 year of age with multiple food allergies, omalizumab treatment for 16 weeks was superior to placebo in increasing the reaction threshold for peanut and other common food allergens. (Funded by the National Institute of Allergy and Infectious Diseases and others; ClinicalTrials.gov number, NCT03881696.).

Sialylation of immunoglobulin E is a determinant of allergic pathogenicity.

Approximately one-third of the world's population suffers from allergies1. Exposure to allergens crosslinks immunoglobulin E (IgE) antibodies that are bound to mast cells and basophils, triggering the release of inflammatory mediators, including histamine2. Although IgE is absolutely required for allergies, it is not understood why total and allergen-specific IgE concentrations do not reproducibly correlate with allergic disease3-5. It is well-established that glycosylation of IgG dictates its effector function and has disease-specific patterns. However, whether IgE glycans differ in disease states or affect biological activity is completely unknown6. Here we perform an unbiased examination of glycosylation patterns of total IgE from individuals with a peanut allergy and from non-atopic individuals without allergies. Our analysis reveals an increase in sialic acid content on total IgE from individuals with a peanut allergy compared with non-atopic individuals. Removal of sialic acid from IgE attenuates effector-cell degranulation and anaphylaxis in several functional models of allergic disease. Therapeutic interventions-including removing sialic acid from cell-bound IgE with a neuraminidase enzyme targeted towards the IgE receptor FcεRI, and administering asialylated IgE-markedly reduce anaphylaxis. Together, these results establish IgE glycosylation, and specifically sialylation, as an important regulator of allergic disease.

Triggers for eosinophilic esophagitis (EoE): The intersection of food allergy and EoE.

Eosinophilic esophagitis and IgE-mediated food allergy are both food-triggered diseases that are increasing in prevalence. They share many clinical links, including significant comorbidity and similar food triggers, and as atopic diseases, they likely share upstream mechanisms related to barrier function and signals leading to TH2 skewing. In this review, we focus on links between eosinophilic esophagitis and IgE-mediated food allergy with an emphasis on what insights may be derived from overlapping food triggers and immune phenotypes. Through further investigation of these connections, we may be able to better understand not only IgE-mediated food allergy and eosinophilic esophagitis but also general atopic response to food proteins and evolution of allergic response to food.

Utility of food allergy thresholds.

Food allergy is a prevalent disease worldwide that is a significant quality-of-life burden, and accidental exposures to food allergens may elicit severe, life-threatening reactions such as anaphylaxis. The threshold level, or the dose that triggers an allergic reaction determined by oral food challenges, varies considerably among individuals suffering from food allergies. Moreover, IgE concentration, diversity, or function can only partially explain this variation in threshold; pathogenic effector TH2 cells have also been found to contribute to the eliciting dose. Though very sensitive to cofactors such as physical activity/stress, the threshold is a stable and reproducible feature of an individual's allergy over periods of many months, made clear in the past several years from treatment studies in which repeated threshold determination has been used as a treatment outcome; however, there also seem to be age-related changes at a population level. More routine determination of food allergy thresholds may help patients stratify risk to improve the management of their food allergy. Precautionary allergen labeling, such as "may contain" labels, often causes confusion since they are inconsistent and regularly contain little to trace allergen residues; thus, food products with such labeling may be unnecessarily avoided. Population-based eliciting dose levels have been determined in the literature; patients at lower risk with higher thresholds may be more confident with introducing foods with precautionary allergen labels. Understanding a patient's threshold level could aid in shared decision-making to determine the most suitable treatment options for patients, including the starting dose for oral immunotherapy and/or the use of biologics.

Breakthroughs in understanding and treating eosinophilic gastrointestinal diseases presented at the CEGIR/TIGERs Symposium at the 2022 American Academy of Allergy, Asthma & Immunology Meeting.

The Consortium of Eosinophilic Gastrointestinal Diseases and The International Gastrointestinal Eosinophil Researchers organized a day-long symposium at the 2022 Annual Meeting of the American Academy of Allergy, Asthma & Immunology. The symposium featured a review of recent discoveries in the basic biology and pathogenesis of eosinophilic gastrointestinal diseases (EGIDs) in addition to advances in our understanding of the clinical features of EGIDs. Diagnostic and management approaches were reviewed and debated, and clinical trials of emerging therapies were highlighted. Herein, we briefly summarize the breakthrough discoveries in EGIDs.

Early infancy dysbiosis in food protein-induced enterocolitis syndrome: A prospective cohort study.

BACKGROUND: The microbiome associations of food protein-induced enterocolitis syndrome (FPIES) are understudied. We sought to prospectively define the clinical features of FPIES in a birth cohort, and investigate for the evidence of gut dysbiosis. METHODS: We identified children diagnosed with FPIES in the Gastrointestinal Microbiome and Allergic Proctocolitis Study, a healthy infant cohort. Children were assessed and stools were collected at each well child visit. The clinical features of the children with FPIES were summarized. Stool microbiome was analyzed using 16S rRNA sequencing comparing children with and without FPIES. RESULTS: Of the 874 children followed up for 3 years, 8 FPIES cases (4 male) were identified, yielding a cumulative incidence of 0.92%. The most common triggers were oat and rice (n = 3, each) followed by milk (n = 2). The children with FPIES were more likely to have family history of food allergy (50% vs. 15.9% among unaffected, p = .03). The average age of disease presentation was 6 months old. During the first 6 months of life, stool from children with FPIES contained significantly less Bifidobacterium adolescentis, but more pathobionts, including Bacteroides spp. (especially Bacteroides fragilis), Holdemania spp., Lachnobacterium spp., and Acinetobacter lwoffii. The short-chain fatty acid (SCFA)-producing Bifidobacterium shunt was expressed significantly less in the stool from FPIES children. CONCLUSIONS: In this cohort, the cumulative incidence over the 3-year study period was 0.92%. During the first 6 months of life, children with FPIES had evidence of dysbiosis and SCFA production pathway was expressed less in their stool, which may play an important role in the pathogenesis of FPIES.

Longitudinal assessment of early growth in children with IgE- and non-IgE-mediated food allergy in a healthy infant cohort.

BACKGROUND: There are conflicting associations reported between food allergies (FAs) and poor growth, with some indication that children with multiple FAs are at highest risk. OBJECTIVE: We analyzed longitudinal weight-for-length (WFL) trajectories from our healthy cohort to evaluate growth in children with IgE-mediated FAs and food protein-induced allergic proctocolitis (FPIAP), a non-IgE-mediated FA. METHODS: Our observational cohort of 903 healthy newborn infants was prospectively enrolled to evaluate the development of FAs. Longitudinal mixed effects modeling was used to compare differences in WFL among children with IgE-FA and FPIAP, compared with unaffected children, through age 2. RESULTS: Among the 804 participants who met inclusion criteria, FPIAP cases had significantly lower WFL than unaffected controls during active disease, which resolved by 1 year of age. In contrast, children with IgE-FA had significantly lower WFL than unaffected controls after 1 year. We also found that children with IgE-FA to cow's milk had significantly lower WFL over the first 2 years of age. Children with multiple IgE-FAs had markedly lower WFL over the first 2 years of age. CONCLUSION: Children with FPIAP have impaired growth during active disease in the first year of age which resolves, whereas children with IgE-FA, particularly those with multiple IgE-FA, have impaired growth more prominently after the first year of age. It may be appropriate to focus nutritional assessment and interventions accordingly during these higher risk periods in these patient populations.

Revealing the heterogeneity of CD4+ T cells through single-cell transcriptomics.

Single-cell RNA sequencing (scRNA-seq) offers the ability to resolve whole transcriptomes of single cells with substantial throughput, and it has revolutionized studies of gene expression. The transcriptional resolution available can uncover fine structures of biologic heterogeneity that are manifest among cell populations. Here, we review the applications of scRNA-seq to profile the phenotypes and clonotypes of CD4+ T cells. First, we describe challenges inherent to scRNA-seq that are important for analysis of CD4+ T cells, as well as the technical solutions that are emerging to address these challenges. We then consider major themes of the application of scRNA-seq to CD4+ T cells, including investigation of CD4+ T-cell heterogeneity in model systems, analysis of populations from the peripheral blood, and the profiling of tissue-resident populations. We place emphasis on capabilities unique to scRNA-seq, such as the ability to obtain paired T-cell receptor and transcriptome information from single T cells and the potential to elucidate interactions between CD4+ T cells and other cells in their environment. Finally, we conclude by considering future areas of technologic advancement and innovation through which scRNA-seq may further shape our understanding of the roles of CD4+ T cells in health and disease.

Safety of peanut (Arachis hypogaea) allergen powder-dnfp in children and teenagers with peanut allergy: Pooled summary of phase 3 and extension trials.

BACKGROUND: Peanut (Arachis hypogaea) allergen powder-dnfp (PTAH; previously known as AR101) is a daily oral immunotherapy approved to mitigate allergic reactions after accidental peanut exposure in peanut-allergic individuals aged 4-17 years. OBJECTIVE: We sought to comprehensively summarize the PTAH safety profile for up to ∼2 years of treatment. METHODS: Safety and adverse event (AE) data from participants aged 4-17 years from 3 controlled, phase 3 and 2 open-label extension trials were pooled and assessed. RESULTS: Of the 944 individuals receiving ≥1 PTAH dose, median exposure was ∼49 weeks; most participants experienced ≥1 treatment-related AE (TRAE; n = 853; 90.4%). A total of 829 participants experienced TRAEs with a maximum severity of mild (497, 52.6%) or moderate (332, 35.2%); 24 participants (2.5%) experienced TRAEs graded as severe. Overall, 80 participants (9.5%) discontinued as a result of AEs; most experienced gastrointestinal symptoms and discontinued during the first 6 months. When adjusted for exposure, AEs and TRAEs occurred at a rate of 76.4 and 58.7 events per participant-year of exposure (PYE), respectively, during updosing; AEs and TRAEs decreased to 23.0 and 14.2, respectively, during 300 mg maintenance. Overall, exposure-adjusted rates of systemic allergic reactions were 0.12 events/PYE (mild), 0.11 events/PYE (moderate), and 0.01 events/PYE (severe [anaphylaxis]). CONCLUSION: The safety profile of PTAH was consistent across trials, manageable, and improved over time. AEs were predominantly mild to moderate, and all grades declined in frequency with continued treatment. These data can be used to facilitate shared decision-making discussions with patients and families considering treatment with PTAH.

Updating the CoFAR Grading Scale for Systemic Allergic Reactions in Food Allergy.

BACKGROUND: Immunotherapy is promising as an efficacious treatment for food allergy. Other food allergy treatments are also under development. However, adverse allergic events during treatment, as well as during oral food challenges, are common and reporting is not standardized. OBJECTIVE: A more nuanced grading scale is needed to create a comprehensive and universal system to categorize adverse events and their severity for food allergy clinical trials. METHODS: Starting with the 2012 Consortium for Food Allergy Research (CoFAR) Grading Scale and the World Allergy Organization Grading System, we developed the CoFAR Grading Scale for Systemic Allergic Reactions, Version 3.0, in collaboration with industry partners with expert opinion. RESULTS: The revised CoFAR Grading Scale for Systemic Allergic Reactions has 5 levels of increasing severity, ranging from generalized urticaria, localized angioedema, rhinitis, and abdominal pain (grade 1) to death (grade 5). Systemic reactions are further categorized within each grade by relevant organ system. Mild, single-system reactions are differentiated from mild, multisystem reactions. Lower respiratory tract symptoms are graded on the basis of response to therapy; those that are refractory to standard treatment (eg, requiring >3 doses of intramuscular epinephrine, continuous intravenous epinephrine infusion, and continuous albuterol nebulization) and respiratory compromise requiring mechanical ventilation are classified as grade 4, life-threatening reactions. CONCLUSIONS: Universal and consistent use of the revised CoFAR Grading Scale beyond the CoFAR centers would allow for better data aggregation and safety comparisons in clinical trials for food allergy.

Kinetics of basophil hyporesponsiveness during short-course peanut oral immunotherapy.

BACKGROUND: Oral immunotherapy (OIT) leads to suppression of mast cell and basophil degranulation along with changes in the adaptive immune response. OBJECTIVES: This study aimed to determine how rapidly these effects occur during OIT and more broadly, the kinetics of basophil and mast cell suppression throughout the course of therapy. METHODS: Twenty participants, age 4 to 12 years, were enrolled in a peanut OIT trial and assessed for desensitization and sustained unresponsiveness after 9 months of therapy. Blood was collected 5 times in the first month and then intermittently throughout to quantify immunoglobulins and assess basophil activation by CD63, CD203c, and phosphorylated SYK (pSYK). RESULTS: Twelve of 16 participants that completed the trial were desensitized after OIT, with 9 achieving sustained unresponsiveness after discontinuing OIT for 4 weeks. Basophil hyporesponsiveness, defined by lower CD63 expression, was detected as early as day 90. pSYK was correlated with CD63 expression, and there was a significant decrease in pSYK by day 250. CD203c expression remained unchanged throughout therapy. Interestingly, although basophil activation was decreased across the cohort during OIT, basophil activation did not correlate with individual clinical outcomes. Serum peanut-specific IgG4 and IgA increased throughout therapy, whereas IgE remained unchanged. CONCLUSIONS: Suppression of basophil activation occurs within the first 90 days of peanut OIT, ultimately leading to suppression of signaling through pSYK.

Designer covalent heterobivalent inhibitors prevent IgE-dependent responses to peanut allergen.

Allergies are a result of allergen proteins cross-linking allergen-specific IgE (sIgE) on the surface of mast cells and basophils. The diversity and complexity of allergen epitopes, and high-affinity of the sIgE-allergen interaction have impaired the development of allergen-specific inhibitors of allergic responses. This study presents a design of food allergen-specific sIgE inhibitors named covalent heterobivalent inhibitors (cHBIs) that selectively form covalent bonds to only sIgEs, thereby permanently inhibiting them. Using screening reagents termed nanoallergens, we identified two immunodominant epitopes in peanuts that were common in a population of 16 allergic patients. Two cHBIs designed to inhibit only these two epitopes completely abrogated the allergic response in 14 of the 16 patients in an in vitro assay and inhibited basophil activation in an allergic patient ex vivo analysis. The efficacy of the cHBI design has valuable clinical implications for many allergen-specific responses and more broadly for any antibody-based disease.

Peanut protein acts as a TH2 adjuvant by inducing RALDH2 in human antigen-presenting cells.

BACKGROUND: Peanut is a potent inducer of proallergenic TH2 responses in susceptible individuals. Antigen-presenting cells (APCs) including dendritic cells and monocytes instruct naive T cells to differentiate into various effector cells, determining immune responses such as allergy and tolerance. OBJECTIVE: We sought to detect peanut protein (PN)-induced changes in gene expression in human myeloid dendritic cells (mDCs) and monocytes, identify signaling receptors that mediate these changes, and assess how PN-induced genes in mDCs impact their ability to promote T-cell differentiation. METHODS: mDCs, monocytes, and naive CD4+ T cells were isolated from blood bank donors and peanut-allergic patients. APCs were incubated with PN and other stimulants, and gene expression was measured using microarray and RT quantitative PCR. To assess T-cell differentiation, mDCs were cocultured with naive TH cells. RESULTS: PN induced a unique gene expression profile in mDCs, including the gene that encodes retinaldehyde dehydrogenase 2 (RALDH2), a rate-limiting enzyme in the retinoic acid (RA)-producing pathway. Stimulation of mDCs with PN also induced a 7-fold increase in the enzymatic activity of RALDH2. Blocking antibodies against Toll-like receptor (TLR)1/TLR2, as well as small interfering RNA targeting TLR1/TLR2, reduced the expression of RALDH2 in PN-stimulated APCs by 70%. Naive TH cells cocultured with PN-stimulated mDCs showed an RA-dependent 4-fold increase in production of IL-5 and expression of integrin α4ß7. CONCLUSIONS: PN induces RALDH2 in human APCs by signaling through the TLR1/TLR2 heterodimer. This leads to production of RA, which acts on TH cells to induce IL-5 and gut-homing integrin. RALDH2 induction by PN in APCs and RA-promoted TH2 differentiation could be an important factor determining allergic responses to peanut.

Ara h 2-specific IgE is superior to whole peanut extract-based serology or skin prick test for diagnosis of peanut allergy in infancy.

BACKGROUND: Screening of high-risk infants for peanut allergy (PA) before introduction is now recommended in the United States, but the optimal approach is not clear. OBJECTIVE: We sought to compare the diagnostic test characteristics of peanut skin prick test (SPT), peanut-specific IgE (sIgE), and sIgE to peanut components in a screening population of infants before known peanut exposure. METHODS: Infants aged 4 to 11 months with (1) no history of peanut ingestion, testing, or reaction and (2) (a) moderate-severe eczema, (b) history of food allergy, and/or (c) first-degree relative with a history of PA received peanut SPT, peanut-sIgE and component-IgE testing, and, depending on SPT wheal size, oral food challenge or observed feeding. Receiver-operator characteristic areas under the curve (AUCs) were compared, and diagnostic sensitivity and specificity were calculated. RESULTS: A total of 321 subjects completed the enrollment visit (median age, 7.2 months; 58% males), and 37 (11%) were found to have PA. Overall, Ara h 2-sIgE at a cutoff point of 0.1 kUa/L discriminated between allergic and nonallergic best (AUC, 0.96; sensitivity, 94%; specificity, 98%), compared with peanut-sIgE at 0.1 kUa/L (AUC, 0.89; sensitivity, 100%; specificity, 78%) or 0.35 kUa/L (AUC, 0.91; sensitivity, 97%; specificity, 86%), or SPT at wheal size 3 mm (AUC, 0.90; sensitivity, 92%; specificity, 88%) or 8 mm (AUC, 0.87; sensitivity, 73%; specificity, 99%). Ara h 1-sIgE and Ara h 3-sIgE did not add to prediction of PA when included in a model with Ara h 2-sIgE, and Ara h 8-sIgE discriminated poorly (AUC, 0.51). CONCLUSIONS: Measurement of only Ara h 2-sIgE should be considered if screening of high-risk infants is performed before peanut introduction.

Age and eczema severity, but not family history, are major risk factors for peanut allergy in infancy.

BACKGROUND: Whether to screen high-risk groups before early peanut introduction is controversial. OBJECTIVE: We sought to determine the risk of peanut allergy (PA) before peanut introduction for infants with (1) moderate-severe eczema, (2) another food allergy (FA), and/or (3) a first-degree relative with peanut allergy (FH). METHODS: Infants aged 4 to 11 months with no history of peanut ingestion, testing, or reaction and at least 1 of the above risk factors received peanut skin prick test and, depending on skin prick test wheal size, oral food challenge or observed feeding. RESULTS: A total of 321 subjects completed the enrollment visit (median age, 7.2 months; 58% males); 78 had eczema only, 11 FA only, 107 FH only, and 125 had multiple risk factors. Overall, 18% of 195 with eczema, 19% of 59 with FA, and 4% of 201 with FH had PA. Only 1% of 115 with FH and no eczema had PA. Among those with eczema, older age (odds ratio [OR], 1.3; 95% CI, 1.04-1.68 per month), higher SCORing Atopic Dermatitis score (OR, 1.19; 95% CI, 1.06-1.34 per 5 points), black (OR, 5.79; 95% CI, 1.92-17.4 compared with white), or Asian race (OR, 6.98; 95% CI, 1.92-25.44) and suspected or diagnosed other FA (OR, 3.98; 95% CI, 1.62-9.80) were associated with PA. CONCLUSIONS: PA is common in infants with moderate-severe eczema, whereas FH without eczema is not a major risk factor, suggesting screening only in those with significant eczema. Even within the first year of life, introduction at later ages is associated with a higher risk of PA among those with eczema, supporting introduction of peanut as early as possible.

AR101 Oral Immunotherapy for Peanut Allergy.

BACKGROUND: Peanut allergy, for which there are no approved treatment options, affects patients who are at risk for unpredictable and occasionally life-threatening allergic reactions. METHODS: In a phase 3 trial, we screened participants 4 to 55 years of age with peanut allergy for allergic dose-limiting symptoms at a challenge dose of 100 mg or less of peanut protein (approximately one third of a peanut kernel) in a double-blind, placebo-controlled food challenge. Participants with an allergic response were randomly assigned, in a 3:1 ratio, to receive AR101 (a peanut-derived investigational biologic oral immunotherapy drug) or placebo in an escalating-dose program. Participants who completed the regimen (i.e., received 300 mg per day of the maintenance regimen for approximately 24 weeks) underwent a double-blind, placebo-controlled food challenge at trial exit. The primary efficacy end point was the proportion of participants 4 to 17 years of age who could ingest a challenge dose of 600 mg or more, without dose-limiting symptoms. RESULTS: Of the 551 participants who received AR101 or placebo, 496 were 4 to 17 years of age; of these, 250 of 372 participants (67.2%) who received active treatment, as compared with 5 of 124 participants (4.0%) who received placebo, were able to ingest a dose of 600 mg or more of peanut protein, without dose-limiting symptoms, at the exit food challenge (difference, 63.2 percentage points; 95% confidence interval, 53.0 to 73.3; P<0.001). During the exit food challenge, the maximum severity of symptoms was moderate in 25% of the participants in the active-drug group and 59% of those in the placebo group and severe in 5% and 11%, respectively. Adverse events during the intervention period affected more than 95% of the participants 4 to 17 years of age. A total of 34.7% of the participants in the active-drug group had mild events, as compared with 50.0% of those in the placebo group; 59.7% and 44.4% of the participants, respectively, had events that were graded as moderate, and 4.3% and 0.8%, respectively, had events that were graded as severe. Efficacy was not shown in the participants 18 years of age or older. CONCLUSIONS: In this phase 3 trial of oral immunotherapy in children and adolescents who were highly allergic to peanut, treatment with AR101 resulted in higher doses of peanut protein that could be ingested without dose-limiting symptoms and in lower symptom severity during peanut exposure at the exit food challenge than placebo. (Funded by Aimmune Therapeutics; PALISADE ClinicalTrials.gov number, NCT02635776 .).

Gastrointestinal immunopathology of food protein-induced enterocolitis syndrome and other non-immunoglobulin E-mediated food allergic diseases.

OBJECTIVE: To provide a concise summary of the current literature regarding gastrointestinal immunopathology of food protein-induced enterocolitis syndrome (FPIES) and other non-immunoglobulin E (IgE)-mediated food allergic diseases. DATA SOURCES: Data were extracted from PubMed, MEDLINE, and ScienceDirect databases. STUDY SELECTIONS: Original articles, review articles, and guidelines published in the past 5 years in peer-reviewed journals were first summarized. The original articles cited were then reviewed and relevant results were extracted. RESULTS: Patients with FPIES and non-IgE-mediated food allergic diseases developed vomiting, diarrhea, and food aversion expelled food allergen from their bodies. Aside from T helper type 2 (TH2) immunity, TH1, TH17, innate immunity, and epithelial mucosal barrier defect were also found to be important in the pathogenesis. Eosinophils, widely identified in the biopsy samples, were key players or were late-recruited cells for tissue repairs in those diseases. Intestinal dysbiosis and their metabolites stimulated enterochromaffin cells or enteroendocrine cells to produce serotonin, interfering with intestinal motility and subsequently affecting brain function. FPIES and non-IgE-mediated food allergic diseases were likely part of the atopic march. Allergic inflammation in intestinal mucosa might result in subsequent inflammation in the airway mucosa, suggesting the theory of "one mucosa, one disease." CONCLUSION: The immune responses of FPIES and non-IgE-mediated food allergic diseases were not limited to the gastrointestinal tract, but also trigger wider inflammatory responses beyond it. Further research will be required to determine the systemic effect and intestinal microbiome of those diseases.

Expansion of the CD4+ effector T-cell repertoire characterizes peanut-allergic patients with heightened clinical sensitivity.

BACKGROUND: Individuals with peanut allergy range in clinical sensitivity: some can consume grams of peanut before experiencing any symptoms, whereas others suffer systemic reactions to 10 mg or less. Current diagnostic testing only partially predicts this clinical heterogeneity. OBJECTIVE: We sought to identify characteristics of the peanut-specific CD4+ T-cell response in peanut-allergic patients that correlate with high clinical sensitivity. METHODS: We studied the T-cell receptor ß-chain (TCRß) usage and phenotypes of peanut-activated, CD154+ CD4+ memory T cells using fluorescence-activated cell sorting, TCRß sequencing, and RNA-Seq, in reactive and hyporeactive patients who were stratified by clinical sensitivity. RESULTS: TCRß analysis of the CD154+ and CD154- fractions revealed more than 6000 complementarity determining region 3 sequences and motifs that were significantly enriched in the activated cells and 17% of the sequences were shared between peanut-allergic individuals, suggesting strong convergent selection of peanut-specific clones. These clones were more numerous among the reactive patients, and this expansion was identified within effector, but not regulatory T-cell populations. The transcriptional profile of CD154+ T cells in the reactive group skewed toward a polarized TH2 effector phenotype, and expression of TH2 cytokines strongly correlated with peanut-specific IgE levels. There were, however, also non-TH2-related differences in phenotype. Furthermore, the ratio of peanut-specific clones in the effector versus regulatory T-cell compartment, which distinguished the clinical groups, was independent of specific IgE concentration. CONCLUSIONS: Expansion of the peanut-specific effector T-cell repertoire is correlated with clinical sensitivity, and this observation may be useful to inform our assessment of disease phenotype and to monitor disease longitudinally.