Background: Respiratory birch pollen allergy and associated oral allergy syndrome affect more than 150 million people. IgE cross-sensitization to major birch pollen allergen Bet v 1 and pathogenesis-related (PR10) plant food allergens is responsible for the pollen-food allergy syndrome. Methods: We designed a recombinant protein, AB-PreS, consisting of non-allergenic peptides derived from the IgE binding sites of Bet v 1 and the cross-reactive apple allergen, Mal d 1, fused to the PreS domain of HBV surface protein as immunological carrier. AB-PreS was expressed in E. coli and purified by chromatography. The allergenic activity of AB-PreS was tested using sera and basophils from birch pollen patients allergic. The protective effect of AB-PreS was assessed by inhibition ELISA test using sera allergic patients and from immunized rabbits. Results: IgE-binding experiments and basophil activation test revealed the hypoallergenic nature of AB-PreS. IgG antibodies induced by 5 injections with AB-PreS inhibited allergic patients’ IgE binding to Bet v 1 and Mal d 1 better than did IgG induced by up to 30 injections of six licensed birch pollen allergen extract-based vaccines. Additionally, immunization with AB-PreS induced HBV-specific antibodies potentially protecting the infection. Conclusion: The recombinant AB-PreS-based vaccine is hypoallergenic, safe and superior to currently registered allergen extract-based vaccines for the treatment of the birch pollen food allergy syndrome.

The field of medicine is witnessing an exponential growth of interest in Artificial Intelligence (AI), which enables new research questions and the analysis of larger and new types of data. Nevertheless, applications that go beyond proof of concepts and deliver clinical value remain rare, especially in the field of allergy and immunology. This narrative review provides a fundamental understanding of the core concepts of AI and critically discusses its limitations and open challenges, such as data availability and bias, along with potential directions to surmount them. We provide a conceptual framework to structure AI applications within this field and discuss forefront case examples. Most of these applications of AI and machine learning in allergy concern supervised learning and unsupervised clustering, with a strong emphasis on diagnosis and subtyping. A perspective is shared on guidelines for good AI practice to guide readers in applying it effectively and safely, along with prospects of field advancement and initiatives to increase clinical impact. We anticipate that AI can further deepen our knowledge of disease mechanisms and contribute to precision medicine in allergy.

Insect venom allergy is the most frequent cause of anaphylaxis in Europe and possibly worldwide. The majority of systemic allergic reactions after insect stings are caused by Hymenoptera and among these, vespid genera induce most of the systemic sting reactions (SSR). Honey bees are the second leading cause of SSR. Depending on the global region, other Hymenoptera such as different ant genera are responsible for SSR. Widely distributed hornets and bumblebees or local vespid or bee genera rarely induce SSR. Hematophagous insects such as mosquitoes and horse flies usually cause (large) local reactions while SSR occasionally occur. This position paper aims to identify either rare or locally important insects causing SSR as well as rarely occurring SSR after stings or bites of widely distributed insects. We summarized relevant venom or saliva allergens and intended to identify possible cross-reactivities between the insect allergens. Moreover, we aimed to locate diagnostic tests for research and routine diagnosis, which are sometimes only regionally available. Finally, we gathered information on disposable immunotherapies. Major allergens of most insects were identified, and cross-reactivity between insects was frequently observed. While some diagnostics and immunotherapies are locally available, standardized skin tests and immunotherapies are generally lacking in rare insect allergy.

Autoimmunity is the break of tolerance to self-antigens that leads to organ-specific or systemic diseases characterized by the presence of pathogenic autoreactive antibodies (AAb) produced by plasmablast and/or plasma cells. AAb are prevalent in the general population and not systematically associated with clinical symptoms. In contrast, in some individuals, these AAb are pathogenic and drive the development of signs and symptoms of antibody-mediated autoimmune diseases (AbAID). AAb production, isotype profiles, and glycosylations are promoted by pro-inflammatory triggers linked to genetic, environmental, and hormonal parameters. Recent evidence supports a role for pathogenic AAb of the IgE isotype in a number of AbAID. Autoreactive IgE can drive the activation of mast cells, basophils and other types of FcεRI-bearing cells and may play a role in promoting autoantibody production and other pro-inflammatory pathways. In this review, we discuss the current knowledge on the pathogenicity of autoreactive IgE in AbAID and their status as therapeutic targets. We also highlight unresolved issues including the need for assays that reproducibly quantify IgE AAbs, to validate their diagnostic and prognostic value, and to further study their pathophysiological contributions to AbAID.

CLA + memory T cells constitute a small subset of human memory T cells. Circulating skin-homing T cells participate in several aspects of atopic dermatitis, such as Staphylococcus aureus involvement in inflammation, the abnormal Th2 immune response, biomarkers, clinical aspects of the patients, pruritus, and the mechanism of action of targeted therapies. Superantigens, IL-13, IL-31, pruritus, CCL17 and early effects on dupilumab-treated patients have in common that they are related to CLA + T cell response in patients. The function of CLA + T cells is closely related to the role of T cells belonging to the skin-associated lymphoid tissue and could be a reason why they reflect different mechanisms of atopic dermatitis. The goal of this review is to gather all this translational information of atopic dermatitis pathology.

Journal: Allergy

While both the incidence and general awareness of food allergies is increasing, the variety and clinical availability of therapeutics remain limited. Therefore, investigations into the potential factors contributing to the development of food allergy and the mechanisms of natural tolerance or induced desensitization are required. In addition, a detailed understanding of the pathophysiology of food allergies is needed to generate compelling, enduring, and safe treatment options. New findings regarding the contribution of barrier function, the effect of emollient interventions, mechanisms of allergen recognition, and the contributions of specific immune cell subsets through rodent models and human clinical studies provide novel insights. With the first approved treatment for peanut allergy, the clinical management of food allergy is evolving towards less intensive, alternative approaches involving fixed doses, lower maintenance dose targets, co-administration of biologicals, adjuvants, and tolerance-inducing formulations. The ultimate goal is to improve immunotherapy and develop precision-based medicine via risk phenotyping allowing optimal treatment for each food-allergic patient.

Meglumine gadoterate induces immunoglobulin-independent human mast cell activation and MRGPRX2 internalizationTo the Editor,Gadolinium-based contrast agents (GBCA) are intravenous drugs used to enhance resolution in magnetic resonance imaging. They can induce immediate hypersensitivity reactions, yet their pathogenic mechanisms remain poorly characterized. This hampers the ability to predict which patients are at risk of developing them.1 In fact, affected patients usually show negative skin-tests and can react upon the first known GBCA exposure, which implies that IgE-independent mechanisms might be driving this inflammatory response.The Mas-related G protein-coupled receptor member X2 (MRGPRX2) has been recently associated with non-IgE mediated immediate hypersensitivity reactions.2 Some drugs, such as fluoroquinolones, vancomycin, neuromuscular blockade agents, icatibant, morphine, leuprolide and iodinated contrast media, have been reported to activate MRGPRX2, which is highly expressed in mast cells (MCs).3To assess the ability of GBCA to induce non-IgE-mediated hypersensitivity reactions, we stimulated the human MC line LAD2 with several commercial GBCA, namely, meglumine gadoterate, gadobutrol, gadoxetate disodium and gadoteridol. Then, we determined cell viability and degranulation by flow cytometry4 (see a detailed material and methods section in this article´s online supplementary ).Of the GBCA tested, only meglumine gadoterate was able to induce significant MC activation (Figure 1A ) without compromising cell viability (Figure 1B ), as compared to unstimulated MCs. We further assessed MRGPRX2 expression on LAD2 cells by flow cytometry, as well as changes in its expression following stimulations with either meglumine gadoterate or vancomycin (a known agonist of MRGPRX2).5 Under basal conditions, LAD2 cells expressed high levels of MRGPRX2 (Figure 1C ). Following incubation with vancomycin, the level of MRGPRX2 expression was reduced, as compared to untreated LAD2 cells. Interestingly, we observed a similar decrease in MRGPRX2 expression levels upon meglumine gadoterate and vancomycin challenges, as compared to controls, suggesting both the signaling and the internalization of this receptor (Figure 1D ).Meglumine gadoterate is an ionic macrocyclic paramagnetic contrast media. It is composed by gadolinium, which together with the chelating agent tetraxetan (also known as DOTA), yields gadoteric acid. The base meglumine and gadoteric acid form the salt meglumine gadoterate (Figure 2A ). Given that MRGPRX2 has affinity for cationic amphiphilic compounds,6 we ascertained the ability of meglumine to induce MC activation. Meglumine itself induced MC degranulation without affecting cell viability, as compared to untreated cells (Figure 2B ), although a reduction in MRGPX2 expression could not be confirmed (data not shown). Interestingly, meglumine caused MC activation at lower concentrations than meglumine gadoterate, according to the half maximal effective concentration (EC50) of both substances (Figure 2C ). The logarithmically transformed EC50 for meglumine gadoterate was 2.04 (R2= 0.75), and for meglumine was about one order of magnitude lower (1.06; R2= 0.71). Considering the EC50 for meglumine and its proportion in meglumine gadoterate (~26%), meglumine could be its main component responsible for MC degranulation.In conclusion, our study demonstrates the ability of meglumine gadoterate to induce MC activation, by an immunoglobulin-independent mechanism that is likely mediated by MRGPRX2. Furthermore, we have delved into the meglumine gadoterate components that are involved in MC activation, and identified meglumine as a potential causative of non-IgE mediated hypersensitivity reactions. These data raise the possibility that immediate hypersensitivity reactions following intravascular administration of ionic iodinated contrast media may be at least partly mediated by meglumine. Further studies should be performed to define clinically relevant interactions between diverse radiological contrast media and MRGPRX2.Authors: Paula H. Ruiz de Azcárate,1#Rodrigo Jiménez-Saiz,1-4 #* Celia López-Sanz,1 Azahara López-Raigada,5Francisco Vega,5 Carlos Blanco,5*# First authors* Corresponding authorsAffiliations: 1Department of Immunology, Instituto de Investigación Sanitaria Hospital Universitario de La Princesa (IIS-Princesa), Universidad Autónoma de Madrid (UAM), Madrid, Spain.2Department of Immunology and Oncology, Centro Nacional de Biotecnología (CNB)-CSIC, Madrid, Spain.3Faculty of Experimental Sciences, Universidad Francisco de Vitoria (UFV), Madrid, Spain.4Department of Medicine, McMaster Immunology Research Centre (MIRC), Schroeder Allergy and Immunology Research Institute (SAIRI), McMaster University, Hamilton, ON, Canada.5Department of Allergy, Instituto de Investigación Sanitaria Hospital Universitario de La Princesa (IIS-Princesa), Universidad Autónoma de Madrid (UAM), Madrid, Spain.*Co-correspondence to :1) Rodrigo Jiménez-Saiz, Department of Immunology, Instituto de Investigación Sanitaria Hospital Universitario de La Princesa (IIS-Princesa), Diego de León 62, 28006, Madrid, Spain. Email address: [email protected]) Carlos Blanco, Department of Allergy, Instituto de Investigación Sanitaria Hospital Universitario de La Princesa (IIS-Princesa), Diego de León 62, 28006, Madrid, Spain. Email address: [email protected] Funding information: RJS reports grants by the FSE/FEDER through the Instituto de Salud Carlos III (CP20/00043; PI22/00236; Spain), The Nutricia Research Foundation (NRF-2021-13; The Netherlands), New Frontiers in Research Fund (NFRFE-2019-00083; Canada) and SEAIC (BECA20A9; Spain). PHR is supported by the INVESTIGO Program of the Community of Madrid (Spain), which is funded by “Plan de Recuperación, Transformación y Resiliencia” and “NextGenerationEU” of the European Union (09-PIN1-00015.6/2022).Conflict of interest : All the authors have no significant conflicts of interest to declare in relation to this manuscript.References1. Vega F, Lopez-Raigada A, Mugica MV, Blanco C. Fast challenge tests with gadolinium-based contrast agents to search for an alternative contrast media in allergic patients. Allergy.2022;77(10):3151-3153.2. Kolkhir P, Ali H, Babina M, et al. MRGPRX2 in drug allergy: What we know and what we do not know. J Allergy Clin Immunol. 2022.3. Foer D, Wien M, Karlson EW, Song W, Boyce JA, Brennan PJ. Patient Characteristics Associated With Reactions to Mrgprx2-Activating Drugs in an Electronic Health Record-Linked Biobank. J Allergy Clin Immunol Pract. 2022.4. López-Sanz C, Sánchez-Martínez E, Jiménez-Saiz R. Protocol to desensitize human and murine mast cells after polyclonal IgE sensitization. STAR Protocols. 2022;3(4):101755.5. Navines-Ferrer A, Serrano-Candelas E, Lafuente A, Munoz-Cano R, Martin M, Gastaminza G. MRGPRX2-mediated mast cell response to drugs used in perioperative procedures and anaesthesia. Sci Rep.2018;8(1):11628.6. Wolf K, Kühn H, Boehm F, et al. A group of cationic amphiphilic drugs activates MRGPRX2 and induces scratching behavior in mice. J Allergy Clin Immunol. 2021;148(2):506-522.e508.

Title : Distinct and mutually exclusive Ca++ flux- and adenyl cyclase-inducing gene expression profiles of G-Protein-Coupled Receptors on human antigen-specific B cellsAuthors : Iris Chang1,2†, Abhinav Kaushik, PhD1,2†, Pattraporn Satitsuksanoa PhD1, Minglin Yang1, Laura Buergi Msc1, Stephan R. Schneider Msc1, Cezmi A. Akdis, MD1, Kari Nadeau MD, PhD2, Willem van de Veen, PhD1, Mübeccel Akdis, MD, PhD1*1 Swiss Institute of Allergy and Asthma Research (SIAF), University of Zürich, Davos, Switzerland.2 Sean N. Parker Center for Allergy and Asthma Research, Department of Medicine, Stanford University, Palo Alto, CA, USA.† Contributed equally* Corresponding authorB cells play an essential role in allergies by producing allergen-specific IgE, which is a prerequisite for allergen-induced degranulation of mast cells (MCs) and basophils. MCs, basophils, dendritic cells and bacteria are capable of releasing inflammatory mediators including histamine. Histamine is a bioactive amine that exerts its function through binding to histamine receptors (HRs), which are 7-transmembrane G-protein-coupled receptors (GPCRs). There are four types of HRs (HR1-4), wherein HR1 ligation triggers Ca2+ mobilization, HR2 stimulates and increases cAMP concentrations, and HR3 and HR4 inhibit cAMP accumulation1. In the presence of histamine in the environment, high affinity HR1is triggered causing cellular activation, followed by expression of 10 times lower affinity HR2 to regulate the over-inflammatory events. These HRs trigger different intracellular events upon activation, with HR1 as a Ca2+ flux-inducing activating receptor and HR2 as an adenyl cyclase-stimulating suppressive receptor 1,2. Therefore, to explore the response of B-cells in allergic diseases, we analyzed the expression profile of HRs and other GPCRs in B cell clones. We hypothesized that the expression profile of HRs (HR1+ vs HR2+ B cell clones) is associated with significant changes in the expression profile of other GPCRs that govern the downstream cascade of pathways associated with cAMP signaling or Ca2+ mobilization.A total of 27 IgG1 and IgG4 expressing B cell clones were isolated for gene expression analysis under BCR stimulated and unstimulated conditions (Figure 1A and Online Supplementary Methods) . Interestingly, we observed B-cell clones with mutually exclusive expression profile of HRH1 and HRH2 genes (Figure 1B), with more HRH1+ B-cell clones in BCR-stimulated samples than unstimulated samples. The subsequentHRH1+ vs HRH2+ differential gene expression analysis (Figure 1C ), reveal 27 differentially expressed (DE) GPCRs in unstimulated samples, with up-regulated P2RY13  and C5AR1genes  in HRH2 + B-cell clones (Figure 2A) , which are associated with the cAMP signaling and suppressive pathway3,4. To further prioritize the DE GPCRs specifically associated with Ca2+ and cAMP signaling pathways, we reconstructed the co-expression networks and performed the weighted degree analysis across HRH1+ vs HRH2+ clones. The analysis reveals that the purinergic receptor family of GPCRs (i.e. P2RY1 , P2RY13 )  and complement component 5a receptor family of genes (i.e. C5AR1  and C5AR2 ) share highest degree of interactions. These genes are up-regulated inHRH2+ samples and are well-known to affect cAMP signaling pathway3,4 (Figure S1A ). Intriguingly, we also observed upregulation of GPR35  in HRH2 + B cells, which is associated in maintaining a low baseline Ca2+ level5. Similarly, we also observed up-regulation of GPR68 and GPR171 in HRH1 + B cells; both are known to stimulate Ca2+ flux (Online Supplementary Discussion) .Similarly, 28 GPCRs were differentially expressed in BCR-stimulated samples (Figure 2B ), including higher expression of serotonin receptor type 1A (HTR1A ) and HCAR1  (or GPR81 ) inHRH2+ samples, with a cAMP-linked suppressive function. In addition, we also observed upregulation of complement component 5a receptor family of genes (i.e., C5AR1  and C5AR2 ) and GPR35 , in agreement with the trend observed in unstimulatedHRH2 + B-cell clones. Surprisingly, we observed a higher expression of prostaglandin E2 receptor subtype EP4 (PTGER4)  and adenosine A2A receptor (ADORA2A ) in HRH2+ samples3,6, which are known to be associated with activation of cAMP production and share the highest strength of interactions with the cAMP signaling sub-network (Figure S1B ). Among the up-regulated genes in HRH1 + samples, we found three Ca2+ mobilizing genes, i.e., GPR34 ,P2RY10  and PTAFR .The results reported in this study provides data for a novel hypothesis suggesting investigation of co-expressed genes that may play important synergistic or antagonistic regulatory roles in B-cell function.

Germinal centers (GC) are the sites of B cell clonal expansion, somatic hypermutation and clonal selection, a process that leads to the production of antibodies of higher affinity [1](#ref-0001). Efforts have been made to understand the kinetic of events controlling the GC and the production of specific antibodies in protective as well in pathogenic responses, such as autoimmunity and allergy. The ability of newly mutated GC clones to capture and present antigen to T follicular helper cells (Tfh) in the light zone of the GC is crucial for clonal survival and selection. Tfh cells produce IL-21, a key cytokine for the GC reaction and antibody responses [2](#ref-0002). However, it was not understood how IL-21 acts independently on T and B cells to mediate the GC reaction. In this study Quast and colleagues [3](#ref-0003) contribute to elucidate the specific role of IL-21 on the GC reaction and how IL-21 bioavailability affects the outcome of the GC response. They demonstrate that IL-21 influences Tfh cell differentiation and expansion early, before the GC establishment, as well later during GC development, through both autocrine and paracrine mechanisms, regardless of cognate T-B cell interactions.

A document by Carmen H. Li. Click on the document to view its contents.

Direct cleavage and activation of gasdermin B by asthma trigger allergensTo the Editor:Recent fine-mapping studies have pointed to gasdermn B (GSDMB ) as a potential asthma susceptibility gene in 17q21 locus, the strongest and most highly replicated signal in genome-wide association studies1. The GSDMB protein is a member of the gasdermin family that, when cleaved, triggers an inflammatory cell death known as pyroptosis2. Caspase-1 and granzyme A have been shown to cut GSDMB at specific sites to release the N-terminal fragment of the protein (GSDMB-NT) that has the ability to induce pyroptosis in cells, including airway epithelial cells3,4. These findings suggest that the role of GSDMB in asthma lies in its ability to be activated through cleavage to induce pyroptosis; however, it remains unclear whether GSDMB cleavage and activation occur in the context of asthma.Common asthma trigger allergens often possess protease activities that cause airway epithelial injury and inflammation5,6. We thus tested whether the allergens directly cleave GSDMB. Incubation of extracts from house dust mite (HDM), a common asthma trigger, with lysates from human bronchial epithelial cells, which express endogenous GSDMB3, resulted in GSDMB cleavage as evidenced by the appearance of a smaller protein around 17kD (Figure 1A). Since the GSDMB antibody used in the Western blotting targets the C-terminus of the protein, the 17kD protein band likely represents the C-terminal GSDMB fragment. Such GSDMB cleavage was also observed when lysates from cells expressing C-terminal-FLAG-tagged GSDMB were mixed with HDM extract (Figure 1B). Furthermore, mold or cockroach extract also cleaved tagged GSDMB (Figure 1C). The cleavage of GSDMB protein by all allergen extracts resulted in a single product of similar size (about 17 kD), suggesting a specific cutting site.To identify the cleavage site, we incubated recombinant full-length GSDMB with HDM extract and resolved the cleaved protein products on SDS-PAGE (Figure 1D). We excised the putative 17 kD C-terminal fragment (GSDMB-CT, Figure 1D) and determined the N-terminal amino acid sequence of the fragment via Edman sequencing (Supplemental Figure S1, Figure 1E). Despite some ambiguities, the first ten amino acid residues of the 17 kD GSDMB-CT largely map to position 245 to 254 (SLGSEDSRNM) of the full length GSDMB protein (Figure 1E). This result indicates that GSDMB was cleaved immediately after the lysine residue at position 244 (K244). Interestingly, granzyme A also cuts GSDMB at the same K244 site4. To confirm K244 as the site of cleavage, we mutated lysine 244 to alanine (K244A) in GSDMB and tested whether the mutant protein can be cleaved by HDM. As shown by Western blotting, HDM was able to cleave wild type (WT) GSDMB but failed to cleave K244A GSDMB as evidenced by the absence of the 17 kD fragment (Figure 1F).The cleavage of GSDMB by HDM is expected to release an N-terminal fragment of 244 amino acids (GSDMB-NT-K244) (Figure 2A). We next tested whether GSDMB-NT-K244 triggers pyroptosis. Transfection of GSDMB-NT-K244 induced cell morphological changes characteristic of pyroptosis, including rounding up and detachment (Figure 2B). LDH release assay confirmed increased toxicity in these cells (~3.4 fold) as compared to cells transfected with the full-length GSDMB (Figure 2C). Consistent with our previous finding on GSDMB-NT shortened by a functional asthma-associated splice variant3, transfection of a truncated GSDMB-NT from the variant (NT-K231var) did not induce pyroptosis (Figure 2B,C).While future studies are needed to identify the specific proteases within the allergen extracts that cleave GSDMB, our current study demonstrates that asthma triggers such as HDM can directly cleave and activate GSDMB, thus providing biochemical evidence linking GSDMB-mediated pyroptosis to asthma.

Background: Pruritus has been reported as an adverse drug reaction to arsenic trioxide, but the association of arsenic exposure with pruritus has not been systematically investigated. To investigate the association of arsenic exposure with pruritus, we performed observational, interventional, and Mendelian randomization studies. Methods: A cross-sectional study was conducted in Shimen, China. A Mendelian randomization study was conducted to confirm the causal relationship between susceptibility to arsenic toxicity, in terms of genetically predicted percentages of monomethylated arsenic (MMA%) and dimethylated arsenic (DMA%) in urine, and chronic pruritus in the UK Biobank participants. Then, a case-control study in Shimen participants was conducted to determine the biomarker for pruritus, and arsenite-treated mice were used to confirm the biomarker. Last, a randomized, double-blind, placebo-controlled trial was conducted to test the efficacy of naloxone, a μ-opioid receptor antagonist, in arsenic-exposed patients with pruritus in Shimen. Results: Hair arsenic showed a dose-response relationship with the intensity of itch in 1092 participants. The Mendelian randomization analysis confirmed the causal relationship in the UK Biobank participants, with odds ratios of 1.043 for MMA% and 0.904 for DMA% above versus under median. Serum β-endorphin was identified as a significant biomarker associated with the intensity of itch. Consistently, treatment with arsenite in mice upregulated the level of β-endorphin. The randomized controlled trial showed that treatment with sublingual naloxone significantly relieved the intensity of itch in arsenic-exposed participants. Conclusion: Arsenic exposure is associated with pruritus, and β-endorphin serves as a biomarker of pruritus. Naloxone relieves pruritus in patients with [arseniasis](javascript:;).

Title: Some OPA once told me “LKB1 is going to rule me”: the OPA1-LKB1 axis in immune responseAuthors: Contreras N1,2*, Macías-Camero A1,2*, Delgado-Dolset MI1,2.Affiliations: 1Centre for Metabolomics and Bioanalysis (CEMBIO), Department of Chemistry and Biochemistry, Facultad de Farmacia, Universidad San Pablo-CEU, CEU Universities, Urbanización Montepríncipe, 28660 Boadilla del Monte, Madrid, Spain.2Instituto de Medicina Molecular Aplicada Nemesio Díez (IMMA-NM), Departamento de Ciencias Médicas Básicas, Facultad de Medicina, Universidad San Pablo-CEU, CEU Universities, Urbanización Montepríncipe, 28660 Boadilla del Monte, Madrid, Spain.*These authors contributed equallyCorrespondence to: María Isabel Delgado-Dolset , Instituto de Medicina Molecular Aplicada Nemesio Díez (IMMA-NM), Departamento de Ciencias Médicas Básicas, Facultad de Medicina, Universidad San Pablo CEU, CEU Universities, Urbanización Montepríncipe, 28660 Boadilla del Monte, Madrid, Spain.Campus Montepríncipe. Crtra. Boadilla del Monte km 5.3.CP 28668 Boadilla del Monte. Madrid, Spain.Tlf: +34 91 372 47 00 ext. 15068E-mail: [email protected] of interest: The authors have no conflicts of interest to declare.Funding information: The authors received no specific funding for the elaboration of this article.Authorship: All the authors approved the final version of the manuscript as submitted and agreed to be accountable for all aspects of the work.Acknowledgments: The authors acknowledge the support by Instituto de Salud Carlos III (PI18/01467 and PI19/00044), co-funded by FEDER “Investing in your future” for the thematic network and co-operative research centres ARADyAL RD16/0006/0015 and RICORS Red de Enfermedades Inflamatorias (REI) RD21 0002 0008. Authors would also like to recognize the funding by the Ministry of Science and Innovation in Spain (PCI2018-092930), co-funded by the European program ERA HDHL—Nutrition and the Epigenome, project Dietary Intervention in Food Allergy: Microbiome, Epigenetic and Metabolomic interactions (DIFAMEM); and by Fundación Mutua Madrileña (AP177712021). N.C. and A.M.C. are supported by FPI-CEU predoctoral fellowships. The authors would like to thank Dr Domingo Barber, Dr María M Escribese and Dr Alma Villaseñor for their asserted comments.List of abbreviations : 2-HG: 2-HidroxyGlutarate, α-KG: α-KetoGlutarate, CD4: Cluster of Differentiation 4, ETC: Electron Transport Chain, IL17A: InterLeukin 17A, LKB1: Liver-associated Kinase B1, NET: Neutrophil Extracellular Trap, OPA1: Optic Atrophy 1, PHGDH: PHosphoGlycerate DeHydrogenase, Treg: Regulatory T Helper, TH: T HelperIn the last 20 years, increasing evidence has arisen challenging the belief that mitochondria are mere ATP-synthesizing machines, shedding light on their role in cell signaling (1). Metabolites, energy mediators, and physical interactions involving membrane rearrangements are some of the mechanisms involved in mitochondria-driven cell regulation (1). In this sense, energetics plays a role in the development and function of immune cells, and immunometabolism is a flourishing field. Nonetheless, how mitochondria signaling networks, including membrane dynamics, affect T cell development and differentiation remains unclear (2).In a recently published work, Baixauli et al (3) investigated how CD4+ T cell differentiation is influenced by mitochondrial membrane morphology. In vitro analysis showed that elongated mitochondria with tight cristae in TH17 cells correlated with higher levels of the long isoform protein of OPA1 (L-OPA1) when compared to TH1 and TH2 cells. Moreover, they developed an OPA1 knockout mouse model (Opa1Cd4-cre ) which showed that, besides controlling mitochondrial membrane dynamics, OPA1 also regulated IL17A production, suggesting its potential role in the regulation of TH17 cells effector function.To address this matter, a multi-omic approach, including epigenomics, transcriptomics, proteomics, and metabolomics, was applied. They found several changes in the mitochondria due to the lack of OPA1 that could lead to the loss of Il17a expression. First, as a result of a disrupted inner mitochondrial membrane, electron transport chain (ETC) subunits uncouple, leading to an increase in the NADH/NAD+ ratio. Higher levels of NADH, together with an increase in the oxidation of glutamine, promote α-ketoglutarate (α-KG) conversion towards 2-hidroxyglutarate (2-HG) by phosphoglycerate dehydrogenase (PHGDH). 2-HG accumulation increases histone and DNA methylation that lastly alters chromatin accessibility in immune response genes interfering with Il17a expression.Pathway analysis was performed to determine OPA1 intracellular biological mediators, raising LKB1 as its major upstream regulator. While LKB1 activity was increased inOpa1Cd4-cre mice, authors demonstrated thatLkb1 deletion restored cell carbon metabolism and Il17aexpression by reducing the production of PHGDH and other serine biosynthesis enzymes.This article provides a perspective of the OPA1-LKB1 axis and its role in immune regulation in TH17 cells, which grants a deep understanding on how the different types of molecules are intertwined in the disease (4). As for possible limitations, this work was done using solely a mouse model, which, despite being as extraordinary as it is, does not necessarily match the conditions and metabolic changes that take place in human cells (1). It would have been interesting to see some of these experiments being done in T cells from human donors to corroborate these findings, which would be possible by using CRISPR/Cas technology to delete OPA1 and/or LKB1 .Furthermore, it is still necessary to understand how, if at all, OPA1-LKB1 axis regulates other subsets of T cells, such as TH1 or Treg. It is known that LKB1 affects other immune cell types, even within the innate immune response. For example, LKB1 deficiency in mouse dendritic cells results in higher levels of Treg in vivo that promote an immune-suppressed phenotype through mTOR signaling, impairing tumor growth control and protecting against allergic asthma development (5). Moreover, deletion of Lkb1 in mice alveolar macrophages leads to more severe asthma and higher susceptibility to S. aureusinfection through the AMPK pathway (6); and an increased number of neutrophils. Additionally, it has been described that OPA1-dependent ATP production is needed for neutrophil extracellular trap (NET) formation and effective antibacterial defense both in human and mouse neutrophils (7). However, these studies fail to analyze the OPA1-LKB1 relation, which, to our knowledge, has been described for the first time by Baixauli et al. All in all, these authors have uncover the great potential of the OPA-LKB1 axis in the immunometabolism research field.REFERENCES1. Picard M, Shirihai OS. Mitochondrial signal transduction. Cell Metab 2022;34 :1620–1653.2. Shyer JA, Flavell RA, Bailis W. Metabolic signaling in T cells.Cell Res 2020;30 :649–659.3. Baixauli F, Piletic K, Puleston DJ, Villa M, Field CS, Flachsmann LJ et al. An LKB1–mitochondria axis controls TH17 effector function.Nature 2022;610 :555–561.4. Radzikowska U, Baerenfaller K, Cornejo-Garcia JA, Karaaslan C, Barletta E, Sarac BE et al. Omics technologies in allergy and asthma research: An EAACI position paper. Allergy2022;77 :2888–2908.5. Pelgrom LR, Patente TA, Sergushichev A, Esaulova E, Otto F, Ozir-Fazalalikhan A et al. LKB1 expressed in dendritic cells governs the development and expansion of thymus-derived regulatory T cells.Cell Res 2019;29 :406–419.6. Wang Q, Chen S, Li T, Yang Q, Liu J, Tao Y et al. Critical Role of Lkb1 in the Maintenance of Alveolar Macrophage Self-Renewal and Immune Homeostasis. Front Immunol 2021;12 :1–12.7. Amini P, Stojkov D, Felser A, Jackson CB, Courage C, Schaller A et al. Neutrophil extracellular trap formation requires OPA1-dependent glycolytic ATP production. Nat Commun 2018;9 :2958.

TitleMaternal and infant serum carotenoids are associated with infantile atopic dermatitis developmentTo the Editor,Various epidemiological studies have shown that eczema/atopic dermatitis (AD) in infancy is a risk for skin sensitization1 and development of allergic diseases later in life2.Carotenoids are natural pigments biosynthesized by bacteria, fungi, and plants, but not by mammals3; thus, they need to be supplied via dietary intake of vegetables and fruits or certain animal products. Carotenoids positively impact human health and prevents allergic reactions via their provitamin A activity and high antioxidant potential. However, previous studies using food frequency questionnaires that evaluated the association between maternal vegetable intake during pregnancy and eczema in offspring have shown inconsistent results4–6. As these studies did not measure the levels of individual carotenoids in the serum of mothers or children and in breast milk, appropriate nutritional interventions in maternal and early infant intake of vegetables for the prevention of AD remain unclear.In this study, we have measured the levels of total carotenoids and some of their sub-types in the serum of mothers and children and in maternal breast milk, to evaluate the association between carotenoid levels and the presence of AD at 1 year of age in infants.We compared participants’ characteristics and exposures by 1 year of age (Table S1); carotenoid, retinol, and α-tocopherol levels (Table 1) in the serum of participants, with and without AD at 1 year of age, were compared to those in the serum and breast milk of their respective mothers. We found that both the presence of eczema (OR, 31.7; 95%CI[13.2–76.0]) and S. aureus carriage in the skin by 6 months of age (OR, 5.20; 95%CI[2.30–11.75]) were associated with higher odds of AD development at 1 year of age. On the contrary, certain carotenoid levels in the serum and breast milk, including total carotenoids in the maternal blood, were associated with lower odds of AD at 1 year.To avoid multicollinearity in the regression analysis, we selected seven relevant predictive variables among the carotenoid data using VIP scores in the PLS analysis (Table S2). Stepwise logistic regression analysis using explanatory baseline characteristics, exposure by 1 year of age, and the seven selected carotenoid levels revealed that the following variables were significantly related to AD at 1 year of age (Table 2): presence of eczema by 6 months of age (OR, 34.5; P < 0.0001), maternal blood lutein level (unit OR, 0.002; P = 0.002), and infant blood lycopene level at 1 year (unit OR, 0.01; P = 0.007).One strength of this study is that multiple biological sample types were used as proxies for carotenoid intake. The lutein concentration in the maternal blood at 36 weeks of gestation, which was associated with a reduced AD risk at 1 year of age in the multivariate analysis, was significantly correlated with the cord blood lutein level (Table S3). This suggests that lutein ingested during pregnancy is transferred to the fetus and may have an inhibitory effect on the development of AD in infancy. Another strength of this study is that multiple carotenoids were evaluated simultaneously; the concentrations of lutein, zeaxanthin, α-carotene, β-carotene, and lycopene were strongly correlated, suggesting that these nutrients are absorbed together (Table S4).In conclusion, the results of this study suggest that children of mothers with low carotenoid intake during pregnancy are at higher risk for developing infantile AD and are ideal targets for early intervention in allergy prevention. Further studies are needed to clarify whether carotenoid supplementation during pregnancy/in lactating mothers and infants after weaning has a preventive effect on AD development in infancy.Table 1 Levels of each carotenoid, total carotenoids, retinol, and α-tocopherol in each type of sample in participants with or without atopic dermatitis at 1 year of age

The field of food allergy has seen tremendous change over the past 5-10 years with seminal studies redefining our approach to prevention and management and novel testing modalities in the horizon. Early introduction of allergenic foods is now recommended, challenging the previous paradigm of restrictive avoidance. The management of food allergy has shifted from a passive avoidance approach to active interventions that aim to provide protection from accidental exposures, decrease allergic reaction severity and improve the quality of life of food-allergic patients and their families. Additionally, novel diagnostic tools are making their way into the clinical practice with the goal to reduce the need for food challenges and assist physicians in the -- often complex -- diagnostic process. With all the new developments and available choices for diagnosis, prevention and therapy, shared decision-making has become a key part of the medical consultation, enabling patients to make the right choice for them, based on their values and preferences. Communication with patients has also become more complex over time, as patients are seeking advice online and through social media, but the information found online may be outdated, incorrect, or lacking in context. The role of the allergist has evolved to embrace all the above exciting developments and provide patients with the optimal care that fits their needs. In this review, we discuss recent developments, as well as the evolution of the field of food allergy in the next decade.

Background. Because of altered airway microbiome in asthma, we analysed the bacterial species in sputum of patients with severe asthma. Methods. Whole genome sequencing was performed on induced sputum from non-smoking (SAn) and current or ex-smoker (SAs/ex) severe asthma patients, mild/moderate asthma (MMA) and healthy controls (HC). Data was analysed by asthma severity, inflammatory status and transcriptome-associated clusters (TACs). Results. α-diversity at the species level was lower in SAn and SAs/ex, with an increase in Haemophilus influenzae and Moraxella catarrhalis, and Haemophilus influenzae and Tropheryma whipplei, respectively, compared to HC. In neutrophilic asthma, there was greater abundance of Haemophilus influenzae and Moraxella catarrhalis and in eosinophilic asthma, Tropheryma whipplei was increased. There was a reduction in α-diversity in TAC1 and TAC2 that expressed high levels of Haemophilus influenzae and Tropheryma whipplei, and Haemophilus influenzae and Moraxella catarrhalis, respectively, compared to HC. Sputum neutrophils correlated positively with Moraxella catarrhalis and negatively with Prevotella, Neisseria and Veillonella species and Haemophilus parainfluenzae. Sputum eosinophils correlated positively with Tropheryma whipplei which correlated with pack-years of smoking. α- and β-diversities were stable at one year. Conclusions. Haemophilus influenzae and Moraxella catarrhalis were more abundant in severe neutrophilic asthma and TAC2 linked to inflammasome and neutrophil activation, while Haemophilus influenzae and Tropheryma whipplei were highest in SAs/ex and in TAC1 associated with highest expression of IL-13 Type 2 and ILC2 signatures with the abundance of Tropheryma whipplei correlating positively with sputum eosinophils. Whether these bacterial species drive the inflammatory response in asthma needs evaluation.

Basal serum tryptase: