Journal of Allergy and Clinical Immunology最新文献

Background: Human monoclonal IgE antibodies recognizing peanut allergens have recently become available, but we lack a detailed understanding of how these IgEs target allergens.

Objective: To determine the molecular details of the antibody-allergen interaction for a panel of clinically important human IgE monoclonal antibodies and to develop strategies to disrupt disease causing antibody-allergen interactions.

Methods: We identified candidates from a panel of epitope binned human IgE monoclonals that recognize two important and homologous peanut allergens, Ara h 2 and Ara h 6. Crystal structures were determined revealing the interfaces (antigenic sites) of exemplars of five common IgE bins.

Results: Among the common antigenic sites on Ara h 2 and Ara h 6, two sites (A and B) are highly conserved between the allergens, explaining the cross reactivity of antibodies that recognize these sites. Three sites (C, D, and F) involve residues that are not conserved between the allergens. Of the five common sites, three Sites (B, C, and D) involve residues that are only near each other when the allergens are properly folded, such that these sites are conformational. Two additional sites (sites A and F) involve largely linear stretches of amino acids. Site F targeted antibody, 38B7, binds to a peptide sequence DPYSP^OHS, in which hydroxylation of the last proline is critical for binding. This sequence is repeated two or three times depending on the Ara h 2 isoform, enabling 38B7 to induce anaphylaxis as a single monoclonal, without a second antibody. We have mutated key residues in each site and created a panel of hypoallergens, having reduced IgE mAb binding and lacking the ability to induce anaphylaxis in our murine model.

Conclusion: We created a structural map of the IgE antibody response to the most important peanut allergen proteins to enable the design of new allergy immunotherapies and vaccines.

Mast cells (MCs) are heterogeneous tissue-resident effector cells thought to play central roles in allergic inflammatory disease, yet the degree of heterogeneity and nature of these roles has remained elusive. In recent years, advances in tissue culture systems, pre-clinical mouse models, and the continued spread of single-cell RNA sequencing has greatly advanced our understanding of MC phenotypes in health and disease. These approaches have identified novel interactions of MC subsets with immune cells, neurons, and tissue structural cells, changing our understanding of how MCs both drive and help resolve tissue inflammation, reshape tissue microenvironments, and influence host behavior. This review addresses key studies from 2022-2024 that have advanced our understanding of MC biology in mouse and human.

Background: We have recently shown that, during acute severe COVID-19, SARS-CoV-2 spike protein (S) induces a cascade of events resulting in T cell apoptosis. Indeed, by neutralizing the protease activity of its receptor, ACE2, S induces an increase in circulating Angiotensin II (AngII), resulting in monocytic release of reactive oxygen species (ROS) and programmed T cell death.

Objective: Here, we tested whether SARS-CoV-2 mRNA vaccines, known to cause the circulation of the vaccine antigen, S-protein receptor binding domain (RBD), might trigger the same cascade.

Methods: To this aim, we used ELISA to quantify the presence of RBD and AngII in participants' peripheral blood as well as the presence of interferon-γ in the supernatant of peripheral blood mononuclear cells (PBMCs) exposed to S. Monocytic ROS production, T cell apoptosis, and S-induced T lymphocyte proliferation were measured by flow cytometry, and DNA damage by immunofluorescence.

Results: In most vaccinees, we observed the presence of circulating RBD peaking on Day 14, and linked to an increase in AngII plasma levels with a peak on Day 28. This increase correlated with i) the ability of monocytes to produce ROS and to induce ROS-mediated DNA damage in neighboring cells, including PBMCs, ii) CD4⁺ and CD8⁺ T lymphocyte apoptosis, and iii) a poor response to S in vitro from both CD4⁺ and CD8⁺ T cells.

Clinical implications: We observed the same cascade of events triggered by the vaccinal antigen as by SARS-CoV-2 infection. This cascade may account for the suboptimal efficiency of mRNA SARS-CoV-2 vaccines in preventing the infection, the limited vaccine memory, and certain side-effects. In this model, AngII receptor antagonists and/or antioxidants might improve the performance of the SARS-CoV-2 vaccine.

Background: Airway inflammation has a critical role in asthma pathogenesis and pathophysiology. Yet, the molecular pathways contributing to airway inflammation are not fully known, particularly Type-2 (T2) inflammation characterized by both eosinophilia and higher FeNO levels.

Objective: To identify genes whose level of expression in epithelial brushing samples were associated with both bronchoalveolar lavage (BAL) eosinophilia and generation of FeNO.

Methods: We performed segmental allergen bronchoprovocation (SBP-Ag) in participants with asthma, and RNA-sequencing (RNA-seq) analyses of BAL cells and brushing samples before and 48 h after SBP-Ag to identify regulation of eosinophil recruitment and FeNO changes.

Results: Allergen bronchoprovocation increased FeNO levels, which correlated with eosinophilia. Thirteen genes were identified in brushing samples, whose expression changed in response to SBP-Ag and correlated with both airway eosinophilia and FeNO levels after SBP-Ag. Among these 13 genes, the epithelial cell product, CDH26/cadherin-26 contributed to the amplification of T2 inflammation, as reflected by eosinophilia and FeNO, and causal mediation analyses with pro-T2 and pro-eosinophilic cytokine mediators in BAL fluids. Among the genes associated with reduced eosinophilia and FeNO, HEY2 is known to enhance cell proliferation, migration, invasion, and epithelial-to-mesenchymal transition (EMT), as well as to reduce apoptosis.

Conclusion: This unbiased RNA-seq analysis in participants with allergic asthma revealed several epithelial cell genes, particularly CDH26, that may be critical for the development or augmentation of T2 inflammation in asthma.

Background: Chronic hand eczema (CHE) is a common skin disease with different subtypes, but knowledge of the molecular patterns associated with each subtype is limited.

Objective: To characterize the CHE transcriptome across subtypes.

Methods: Using RNA-sequencing, we studied the transcriptome of 220 full-thickness skin biopsies collected from palms, dorsa, and arms from 96 patients with CHE and/or atopic dermatitis (AD) and 32 healthy controls. The primary analysis focused on 16 healthy and 54 lesional CHE palm samples that were further stratified by AD status and unique etiology. Differentially expressed genes (DEGs) were identified across the cohort and Ingenuity pathway analysis (IPA) was used for pathway analysis and upstream regulator prediction.

Results: We identified anatomical site-specific transcriptomic variations, showing unique characteristics in both healthy and CHE-affected palm skin. In CHE palms, we identified 2333 DEGs versus healthy palms. Upregulated genes predominantly involved keratinocyte host inflammation and immune signaling, while downregulated genes were linked to lipid metabolism and epidermal barrier function. IPA revealed numerous activated pro-inflammatory pathways, dominated by Th1 and Th2. Key upstream regulators included type 1 (IFNG, TNF, STAT1, IL-2) and type 2 (IL-4) associated molecules, and IL-1β. Lesional palm signatures were broadly shared across CHE subtypes. No DEGs were found between allergic- and irritant contact dermatitis CHE. Subtype-specific pathway and upstream regulator activity variations were noted.

Conclusion: The lesional CHE transcriptome is primarily shared among subtypes and is characterized by activation of several immune pathways, dominated by Th1 and Th2. Key shared upstream regulators were identified, highlighting potential universal therapeutic targets.

Background: Determining why some upper respiratory illnesses provoke asthma exacerbations remains an unmet need.

Objective: To identify transcriptome-wide gene expression changes associated with colds that progress to exacerbation.

Methods: 208 urban children (6-17 years) with exacerbation-prone asthma were prospectively monitored for up to two cold illnesses. Exacerbation illnesses (Ex+), defined as colds leading to asthma exacerbations requiring systemic corticosteroids within 10 days, were compared to colds that resolved without exacerbation (Ex-). Peripheral blood and nasal lavage samples were collected at baseline and during colds for RNA sequencing. Interferon gene expression was compared between Ex+ and Ex- illnesses. Generalized additive modeling revealed interferon response kinetics. Multiple linear regression models compared interferon expression to clinical variables.

Results: 106 participants were evaluated during 154 colds. There was greater up-regulation of differentially expressed interferon genes during Ex+ illnesses compared to Ex-. Ex+ illnesses had greater average and steeper rise in interferon expression. Within three days of illness, interferon expression was positively associated with nasal rhinovirus quantity (nasal:adjustedR²=0.48, p=0.015; blood:adjustedR²=0.22, p=0.013) and interferon expression was negatively associated with FEV₁ percent predicted (nasal:β=-0.010, p=0.048; blood:β=-0.008, p=0.023). Participants with lower baseline interferon expression had shorter time to exacerbation, higher risk for exacerbation with viral illnesses and greater increase in interferon expression during viral colds (nasal:β=-0.80, p<0.0001; blood:β=-0.75, p<0.0001).

Conclusion: Dysregulated interferon responses are important contributors to asthma exacerbation risk in children. Low baseline interferon expression followed by greater up-regulation of interferon pathways in airway and blood during respiratory illnesses increased exacerbation risk. Targeting this pathway in at-risk individuals holds promise for the personalized prevention of asthma exacerbations.

Background: Hypereosinophilic syndrome (HES) is characterized by blood and tissue hypereosinophilia causing organ damage and/or dysfunction. Mepolizumab, an anti-IL-5 antibody, has recently been approved in this indication. In lymphoid variant (L-)HES, eosinophil expansion is driven by IL-5-producing clonal CD3^-CD4⁺ T cells.

Objective: This study aimed to elucidate the efficacy of mepolizumab in patients with CD3^-CD4⁺ L-HES, and the impact of treatment on aberrant cells and associated biomarkers.

Methods: A biomarker sub-study was conducted during two clinical trials evaluating mepolizumab in HES, a 32-week randomized placebo-controlled trial (200622) followed by a 20-week open-label extension (205203). Patients with CD3^-CD4⁺ and/or clonal T cells, elevated serum TARC/CCL17, sCD25 and/or detectable IL-5 were identified, and their treatment responses were compared to those without these anomalies.

Results: Of the 108 patients enrolled in 200622-205203, 103 consented to this study, including 17 with a CD3^-CD4⁺ T-cell subset. Presence of CD3^-CD4⁺ T cells or sCD25 levels ≥1500 pg/ml was associated with reduced eosinophil-lowering and corticosteroid-sparing effects of mepolizumab. None of the biomarkers were associated with an increased likelihood of experiencing clinical flares. A mepolizumab-induced increase in serum IL-5 was observed, that was significantly higher in patients with CD3^-CD4⁺ T cells. Treatment did not affect CD3^-CD4⁺ T cell counts.

Conclusion: Mepolizumab has a favorable impact on disease flares in patients with CD3^-CD4⁺ L-HES, although reduced eosinophil-depleting and corticosteroid-sparing effects are observed at the currently-approved dose. Further studies are needed to validate these findings on larger patient cohorts, and to explore whether clinical activity other than flares is equally controlled in this disease variant.