Editorial comment on the Special Issue “Omics in Food Allergy”Riccardo Castagnoli1,2, Ivan Taietti1,2,*, Agnes Sze-Yin Leung3, Philippe Eigenmann41. Pediatric Unit, Department of Clinical, Surgical, Diagnostic, and Pediatric Sciences, University of Pavia, Pavia, Italy2. Pediatric Clinic, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy3. Department of Paediatrics, Faculty of Medicine, The Chinese University of Hong Kong, China4. Pediatric Allergy Unit, Department of Pediatrics, Gynecology and Obstetrics, University Hospitals of Geneva, Geneva, SwitzerlandORCID:Riccardo Castagnoli: 0000-0003-0029-9383Ivan Taietti: 0000-0002-0372-523XAgnes Sze-Yin Leung: 0000-0001-8249-4478Philippe Eigenmann: 0000-0003-1738-1826Corresponding author:Ivan Taietti, MD;Pediatric Unit, Department of Clinical, Surgical, Diagnostic, and Pediatric Sciences, University of Pavia, 27100 Pavia, [email protected]; +39 340 7092400.Food allergy (FA), defined as an adverse reaction to food mediated by the immune system, is a significant public health issue with increasing prevalence over the past decades. Although FA affects up to 10% of children, the precise mechanisms underlying FA development and persistence remain inadequately understood1. Food immunotherapy has been successful in increasing the threshold of tolerance in individuals with persistent FA (desensitization), and in a subset, sustained unresponsiveness (remission) can be achieved. A combination of environmental and genetic factors is considered to be involved in the tolerance induction to food allergens. However, to date, it has been difficult to fully dissect the complexity of the biological determinants involved in FA.The emergence of “omics” sciences, including genomics, transcriptomics, proteomics, and metabolomics, is revolutionizing the basic and translational research approach, allowing for the comprehensive study of biological processes through analyzing and integrating multiple datasets from various biological perspectives.Moreover, epigenetic studies that evaluate the role of gene expression modifiers are deepening our understanding of the interaction between genetic predisposition and environmental influences.The Special Issue “Omics in Food Allergy” aims to present current knowledge and future perspectives in the field of FA through the lenses of omics sciences.Chun et al. and Lehmann et al. provide a detailed overview of epigenetic mechanisms involved in FA, including DNA methylation and microRNA (miRNAs)2,3. DNA methylation refers to the covalent addition of a methyl group, typically to a cytosine in a CpG dinucleotide in DNA. This limits access for transcription, frequently in the promoter region, leading to reduced gene expression. Moreover, miRNAs are small RNAs transcribed from intergenic or intronic genomic loci that decrease gene expression by mRNA degradation and translational inhibition. Of note, Chun et al. described two different approaches in investigating FA mechanisms: (i) the epigenome-wide research approach and (ii) candidate-gene investigations. The epigenome-wide research approach identified genomic regions differently methylated and regulated, involved in FA causation, antigen presentation, T cell development, and reaction severity. Candidate-gene investigations focused on Th1, Th2, T regulatory, and innate genes of interest in FA, highlighting the importance of methylation changes in specific candidate genes. In this context, for cow’s milk allergy (CMA), the attention is focused on novel genetic loci involved in Th1/Th2 differentiation pathways and potential B-cell dysfunction4. Of note, miRNA seems to be involved in CMA as demonstrated by the downregulation of mi193a-5p, a post-transcriptional regulator of IL-4 expression, in infants with CMA5. Moreover, methylation levels in peripheral blood mononuclear cells for IL-4, IL-5, IL-10, and IFN-γ negatively correlate with their respective serum cytokine concentrations and vary according to CMA status (active, resolved, or non-CMA). Finally, Chun et al. reviewed ongoing research aimed at finding DNA methylation predictors of food challenges. Initial work based on the concept of epigenetic markers as biomarkers of disease and treatment demonstrated promise for applying DNA methylation markers to potentially improve how we assess and manage patients with FA, but further validation in larger cohorts and work to practically translate such biomarkers to clinical practice is advocated2.Metabolomics may reflect the integration of genetic, transcriptomic, and proteomic variations with environmental factors, thus reflecting molecular processes of diseases. A metabolome approach would facilitate the identification of surrogate metabolite markers correlating with the disease activity and prognosis. Lee et al. reported an updated overview of metabolomics’s current application in the FA field. Alterations to the gut microbiota induced by Western dietary patterns are likely to profoundly affect host immunity and play a significant role in FA. Metabolites of interest include short-chain fatty acids (SCFAs), bile acid metabolites, and tryptophan metabolites due to their essential roles in normal immune development and homeostasis. SCFAs appear to be reduced in FA patients. Of note, it has been shown that bacterial SCFAs could protect against FA as a consequence of a high-fiber diet in mice. Accordingly, a reduction in Bifidobacterium during infancy, with a consequent reduction in SCFA levels is associated with an increased risk of allergy6. In peanut allergy, oral dysbiosis, reduced oral SCFA levels, and increased oral mucosal Th2 cytokine secretion characterize patients affected, and low fecal SCFAs at a young age could raise the risk of developing FA. Bile acid levels in stool seem to be involved in FA development and persistence, but blood level measurements are advocated to better characterize their role. Moreover, sphingolipids may modulate the function of invariant natural killer T cells and contribute to maintaining intestinal balance and protecting against FA through the modulation of the mast cells’ responsiveness. Sphingolipid dysmetabolism is involved in FA development as a consequence of immune dysregulation in modulating the differentiation of regulatory T cells and Th17 cells that is relevant in FA. Interestingly, some fecal sphingolipids seem to confer protection against FA while reduction of other of them seems to be associated with increased risk of FA, likewise the reduction in serum sphingolipids. Unfortunately, no definitive evidence is available to distinguish whether the sphingolipids modulating this FA effect are dietary or microbial-derived. Metabolites of tryptophan from kynurenine and indole pathways are linked to the function of the intestinal barrier and mucosal immune responses (mainly T regulatory cells) and contribute to intestinal homeostasis. A reduction in these pathways is linked to multiple FA in children. To date, the role of omega-3-polyunsaturated fatty acids metabolites is not clearly defined in FA. However, 17-hydroxy-docosahexaenoic acid (17-HDHA) has been reported to inhibit IgE production by B cells and to suppress the differentiation of naïve B cells into IgE-secreting cells7.The gut microbiome (GM) and its metabolic product, as previously mentioned, play an important role in FA development. TheBifidobacteriaceae family and bacteria of theLactobacillales order are consistently reported lower in CMA children. At the same time, the Firmicutes phylum, primarily associated with the Clostridia class, is consistently increased in mice and human studies. It seems discordant with the observation that infants with resolved CMA were reported to have enrichedClostridia class at 3-6 months but with non-conclusive data. However, Savova et al. showed that GM with enriched Clostridiaclass, reduced Lactobacillales order, and reducedBifidobacterium genus is associated with CMA in early life. Emerging evidence shows that prebiotics, probiotics, and symbiotics, may be a promising adjuvant in promoting tolerance acquisition. ElevatedBifidobacterium genus and reduced Clostridia class members were consistently observed post-treatment with Bifidobacteriumstrains probiotics or after lactose-supplemented extensively hydrolyzed formula (EHF) treatment strategy but with decreased levels ofLactobacillus genus in those treated with Bifidobacteriumstrains probiotics. Gaps remain in understanding the relationship between microbiome and immune response and between transcriptomics (including genes related to the immune response) and GM. In vivo ,Bifidobacterium bifidum has been shown to reduce allergy symptoms, lower serum IgE and raise IgG2 levels, decrease the pro-inflammatory cytokines (TNFα, IL- 1β, and IL-6), and increase the anti-inflammatory cytokine IL-10 in CMA-patients8. Recently, fiber diet has been shown to modulate the disease course of FA through diet-driven changes in the GM9. It is necessary to conduct further research on the impact of GM on FA development and persistence.Lastly, oral immunotherapy (OIT) may provide an active treatment that enables to increase the amount of food that the patient can intake without reaction during treatment (i.e., desensitization), and reduces the risk of potential life-threatening allergic reaction in the event of accidental ingestion10 Unfortunately, there are still significant gaps in understanding the immune mechanisms following OIT, but increasing knowledge about transcriptional pathways associated with its outcomes is available to date11. Ashley et al.12 show that OIT-induced remission of FA is linked to the anergic T cell state mediated by anergy of memory T cells associated with mantained T regulatory cell activity. Suppression of the Th2 transcriptional signals in Th2A-like cells was linked to desensitization following OIT. Moreover, the dampened Th2 and Th1 signatures in effector cells are linked with FA remission, while baseline inflammatory signals in Th1 and Th17 effector cells were associated with poorer outcomes following OIT. Type I interferons were recently identified as potential regulators of remission following OIT because of their key role in the suppression of the Th2 antigen response through regulatory action on GATA3 and the high-affinity IgE receptor. Moreover, an early transient increase in TGF-β producing cells one year into treatment seems to be associated with good clinical outcomes. In addition, persistent activation of FOXP3, expressed by T regulatory cells, may be a critical requirement for lasting persistence of remission12.Comprehensive multi-omics studies are essential to understand FA mechanistically, as highlighted by this Special Issue. “Omics” studies of FA are of great interest as they allow for a thorough understanding of the complexity of FA development and therapeutic outcomes. This has a fundamental impact on approaches to precision medicine.

Monitoring is a major component of asthma management in children. Regular monitoring allows for diagnosis confirmation, treatment optimization and natural history review. Numerous factors that may affect disease activity and patient wellbeing need to be monitored: response and adherence to treatment, disease control, disease progression, comorbidities, quality of life, medication side-effects, allergen and irritant exposures, diet and more. However, the prioritization of such factors and the selection of relevant assessment tools is an unmet need. Furthermore, rapidly developing technologies promise new opportunities for closer, or even ‘real-time’, monitoring between visits. Following an approach that included needs assessment, evidence appraisal and Delphi consensus, the PeARL Think Tank, in collaboration with major international professional and patient organizations, has developed a set of 24 recommendations on pediatric asthma monitoring, to support healthcare professionals in decision-making and care pathway design.

Introduction Patients with food allergies necessite having personalized information on their risk of reaction in “real-life” situations. This multicentric study aimed to investigate the link during accidental reactions between the nature and amount of food allergens consumed in “real life situation” and the severity of the symptoms. Methods Patients were prospectively recruited from the 1 st of December 2020 to the 31 st of December 2021 at the emergency departments in the Geneva University Hospitals and local pediatric urgent care, trough the allergology outpatient consultation, at school and daycare facilities and trough their primary care physicians. Medical history of patients presenting reactions suggestive with immediate food allergy and suspected food samples were collected. Allergy diagnostic tests were retrospectively and prospectively collected. The samples were analyzed for their allergen content. Results We recruited 147 subjects with an accidental immediate-type allergic reaction to a food. We were able to collect 115 reaction-eliciting food samples allowing to quantify the allergen amount occasioning the reaction, as well as correlating this amount to the severity of the reaction. Children represented a large part of the reactors, and most reactions were to common food allergens such as tree nuts, cow’s milk as well as peanuts and hen’s egg. Reactions were mostly to pre-packaged foods and seven were to products with Precautionary allergy labeling, or without labelling to the corresponding allergen. Reactions were of various degrees of severity, and independent to the amount of allergen ingested. Discussion The severity of reactions did not show a direct correlation with allergen quantity, emphasizing individual sensitivity. Some reactions occurred with allergen amounts significantly below the legal limit for mandatory labelling of 1 g/kg in Switzerland. The study also highlighted considerable variability in allergen concentrations in foods labeled with possible “contaminations” or “traces.” These findings raise questions about the accuracy of allergen labeling and regulations.

Prolonged drug provocation with an initial full therapeutic dose to diagnose serum sickness-like reactions (SSLR) to β-lactams in childrenMarcel M Bergmanna,b,c, Eva Gomesd, Natalia Blanca-Lópeze, Jean-Christoph Caubeta, Philippe A Eigenmanna , Giulia Liccioli f, Francesca Morif, Marina Atanaskovic Markovicga Pediatric allergy unit, Department of women, children and adolescents, University Hospitals of Geneva, Geneva, Switzerlandb Centro Pediatrico del Mendrisiotto, Mendrisio, Switzerlandc Faculty of Biomedical Science, Università della Svizzera Italiana (USI), Lugano, Switzerlandd Serviço de Imunoalergologia, Centro Hospitalar Universitário do Porto, Porto, Portugale Servicio de Alergia, Laboratorio de Investigación, Hospital Universitario Infanta Leonor, Madrid, Spainf Allergy Unit, Meyer Children’s University Hospital, IRCCS, Florence, Italyg University of Belgrade Faculty of Medicine, University Children’s Hospital, Belgrade, Serbia

Editorial Comment on: „Short-acting β 2 -agonist use and asthma exacerbations in Swedish children: A SABINA Junior study.”Boccabella C. 1, Kalayci O. 2, Eigenmann P. 3Affiliations1Department of Cardiovascular and Thoracic Sciences, Fondazione Policlinico Universitario “A Gemelli” - IRCCS, University of the Sacred Heart, Rome, Italy2Pediatric Allergy and Asthma Unit, Hacettepe University School of Medicine, Ankara, Turkey3Pediatric Allergy Unit, Department of Women-Children-Teenagers, University Hospitals of Geneva, Geneva, SwitzerlandAsthma is one of the most common chronic lung diseases with major public health consequences for both children and adults, including high morbidity and even mortality (1). For years, standard asthma treatment for mild asthma has been as needed short acting beta agonist (SABA). Global Initiative for Asthma (GINA) guidelines have questioned this approach suggesting that the use of SABAs should always be accompanied by inhaled corticosteroids (ICSs) (2). Recently, Papi et al. have shown that in adolescents and adults with uncontrolled moderate-to-severe asthma receiving inhaled glucocorticoid-containing maintenance therapies, the risk of severe asthma exacerbation was significantly lower with as-needed use of a fixed-dose combination of albuterol and budesonide than with as-needed use of albuterol alone (3). In children, on the other hand, even though many years ago Martinez et al. have shown that inhaled corticosteroids as rescue medication with albuterol might be an effective step-down strategy for children aged 5-18 years with well controlled mild asthma , SABA has remained to be the only reliever option recommended for those under 6 years of age (4).The SABA use IN Asthma (SABINA) program in adults and adolescents with asthma reported that SABA overuse (≥3 canisters/year) is prevalent in Sweden and is associated with poor asthma-related outcomes (5). Melen et al and the SABINA Junior investigators have attempted to investigate the same question in the paediatric population (6). This retrospective cohort study conducted in Sweden, has included patients with physician-diagnosed asthma (aged 0-17 years) in secondary care. Patients have been categorized by the number of SABA canisters collected (dichotomized as 0-2 vs ≥3, based on evidence from studies in adults and adolescents) from pharmacies at baseline and followed up over 12 months (5,7). During the baseline year, SABA overuse (≥3 canisters) has been registered for the majority of the study population, particularly for those aged 0-5 years. A strong correlation between SABA overuse and increased risk of exacerbation episodes has been observed. This result confirms what has been already seen among adult patients, that is strongly connected to the inflammatory nature of asthma disease. SABAs can resolve the immediate bronchospasm but have no anti-inflammatory actions and no effect on the late phase of inflammation. Furthermore, chronic and long-term use of SABAs seems also to contribute to a decreased response to SABA therapy as a reliever (8,9). SABINA investigators have also conducted a post-hoc analysis, stratifying study population based on the presence of atopic comorbidity. Interestingly, increased SABA use has been associated with a higher exacerbation risk also in nonatopic patients with asthma. This may be due to the lack of response to ICSs that is a distinctive aspect of non-atopic population who may in turn resort to the use SABA reliever treatment.There are still several questions that remain unanswered in children mainly due to the difficulties in obtaining data in this specific population. First, recruitment of paediatric patients especially those <6 years old into randomized controlled trials (RCTs) can be a challenge due to ethical issues. In addition, diagnosis of asthma in this age group is often problematic. Despite all the limits of a retrospective study, SABINA study provides extremely useful data in a population where there are hardly any solid data. These results emphasize the need for a better understanding of childhood asthma endotypes and the response to different drugs and disease behaviour over time. Avoiding asthma exacerbations and consequent disease progression should be the principal aim of clinical management in children. This may only be possible by linking the underlying pathophysiology with the clinical response to anti-asthma treatment.References1. Asher MI, Rutter CE, Bissell K, Chiang CY, El Sony A, Ellwood E, et al. Worldwide trends in the burden of asthma symptoms in school-aged children: Global Asthma Network Phase I cross-sectional study. Lancet. 2021;398(10311):1569–80.2. GINA committee. Global Strategy for Asthma Management and Prevention 2022 Update [Internet]. Global Initiative for Asthma. 2022. p. 225. Available from: http://www.ginasthma.org3. Alberto Papi, M.D., Bradley E. Chipps, M.D., Richard Beasley, D.Sc., Reynold A. Panettieri, Jr., M.D., Elliot Israel, M.D., Mark Cooper, M.Sc., Lynn Dunsire, M.Sc., Allison Jeynes-Ellis, M.D., Eva Johnsson, M.D., Robert Rees, Ph.D., Christy Cappelletti, P MD. Albuterol–Budesonide Fixed-Dose Combination Rescue Inhaler for Asthma. N Engl J Med [Internet]. 2022 Aug 17;387(7):662–3. Available from: https://doi.org/10.1056/NEJMc22091894. Martinez L, Handel A, Shen Y, Chakraburty S, Quinn FD, Stein CM, et al. detect tuberculosis in child contacts are urgently needed in Sub-Saharan Africa to improve case detection. n. 2018;197(9):2016–9.5. Nwaru BI, Ekström M, Hasvold P, Wiklund F, Telg G, Janson C. Overuse of short-acting β2-agonists in asthma is associated with increased risk of exacerbation and mortality: A nationwide cohort study of the global SABINA programme. Eur Respir J [Internet]. 2020;55(4). Available from: http://dx.doi.org/10.1183/13993003.01872-20196. Melen E., Nwaaru B., Wiklund F., Licht S., Telg G., Maslova E., Valk R., Tran TN, Ekstrom M. JC. Short-acting β 2 -agonist use and asthma exacerbations in Swedish children: A SABINA Junior study. Pediatr Allergy Immunol Manuscr.7. Bloom CI, Cabrera C, Arnetorp S, Coulton K, Nan C, van der Valk RJP, et al. Asthma-Related Health Outcomes Associated with Short-Acting β2-Agonist Inhaler Use: An Observational UK Study as Part of the SABINA Global Program. Adv Ther [Internet]. 2020;37(10):4190–208. Available from: https://doi.org/10.1007/s12325-020-01444-58. Lohse MJ, Benovic JL, Caron MG, Lefkowitz RJ. Multiple pathways of rapid β2-adrenergic receptor desensitization. Delineation with specific inhibitors. J Biol Chem. 1990;265(6):3202–11.9. Gauvreau GM, Jordana M, Watson RM, Cockcroft DW, O’Byrne PM. Effect of regular inhaled albuterol on allergen-induced late responses and sputum eosinophils in asthmatic subjects. Am J Respir Crit Care Med. 1997;156(6):1738–45.

Multisystem inflammatory syndrome in children (MIS-C) is a rare, but severe complication of coronavirus disease 2019 (COVID-19). It develops approximately four weeks after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and involves hyperinflammation with multisystem injury, commonly progressing to shock. The exact pathomechanism of MIS-C is not known, but immunological dysregulation leading to cytokine storm plays a central role. In response to the emergence of MIS-C, the European Academy of Allergy and Clinical Immunology (EAACI) established a task force (TF) within the Immunology Section in May 2021. With the use of an online Delphi process, TF formulated clinical statements regarding immunological background of MIS-C, diagnosis, treatment, follow-up, and the role of COVID-19 vaccinations. MIS-C case definition is broad, and diagnosis is made based on clinical presentation. The immunological mechanism leading to MIS-C is unclear and depends on activating multiple pathways leading to hyperinflammation. Current management of MIS-C relies on supportive care in combination with immunosuppressive and/or immunomodulatory agents. The most frequently used agents are systemic steroids and intravenous immunoglobulin. Despite good overall short-term outcome, MIS-C patients should be followed-up at regular intervals after discharge, focusing on cardiac disease, organ damage, and inflammatory activity. COVID-19 vaccination is a safe and effective measure to prevent MIS-C. In anticipation of further research, we propose a convenient and clinically practical algorithm for managing MIS-C developed by the Immunology Section of the EAACI.

Editorial to the special issue “Environmental influences on childhood asthma”Back in 1892, Sir William Osler gave an accurate description of asthma as a disease that is associated with “spasm of the bronchial muscles, inflammation of the smaller bronchioles, bizarre and extraordinary variety of circumstances and cold infections, often running in families (1,2). This is basically a true reflection of our modern understanding of asthma which states that asthma is a complex genetic disorder that involves interactions between genetic and environmental factors.Since the human genetic makeup has not changed significantly in the last couple of decades, there is reason to believe that the overall increase in asthma prevalence (3) can be attributed to the changing environmental conditions of modern life. The role of environment in asthma is not limited to its role in the pathogenesis of the disease. Since it is currently not possible to change the genetic make-up of an individual underlying a complex genetic disorder such as asthma, modification of environmental conditions emerges as a significant tool for its treatment. Therefore, understanding the environmental factors that play an important role in asthma is crucial in understanding the disease pathogenesis as well as modification of factors that modulate the inception and progress of the disease as well as its treatment.Various studies published in the last years in the journal and included in this virtual issue have addressed these questions. Garcia-Serna et al. have found out that gestational exposure to traffic-related air pollutants (TRAP) may increase the pro-inflammatory and Th2-related cytokines in newborns which might influence immune system responses later in life (4). Similarly, Pesce et al. (5) have investigated the association between prenatal exposures to heavy metals and atopic diseases. The serum concentrations of lead, cadmium and manganese were assessed in maternal blood samples collected during pregnancy and in cord blood of 651 mother-children pairs. The authors have concluded that the levels of cadmium in cord blood were associated with greater risk of asthma at the age of 8. Baek et al. have documented that exposure to phthalates are associated with airway dysfunction in childhood and this effect was partially attributable to increased serum periostin levels (6). Regarding the association between the genes and environment, Theodorou et al. (7) have investigated the role of mitogen-activated protein kinase (MAPK) pathway in 232 children who were selected from two cross-sectional cohorts and one birth cohort study. They have isolated peripheral blood mononuclear cells (PBMC) from children with asthma along with healthy controls and stimulated them with farm-dust extracts or lipopolysaccharide. The results have shown that the children with asthma have expressed significantly less dual-specificity phosphatase-1 (DUSP1) which is the negative regulator of MAPK pathway. They have conclusively indicated the possible role of DUSP1 for future therapeutical interventions regarding the anti-inflammatory features of farming environments.In an effort to further elucidate the environmental factors that are central to our understanding of asthma, the journal has started a review series to provide a comprehensive picture on the role of environment on various aspect of asthma. Major subheadings includedBiodiversityUrban exposuresGene-environment interactionsFarm effectAir pollutionClimate changeAllergensDiet microbiome and obesityIn the virtual issue of the journal Tari Haahtela (8) has focused on the effect of biodiversity. Evidence supports that the immunomodulating roles of different micro-organisms may be protective for asthma and allergic diseases. The studies from the neighboring Finnish and Russian Karelia regions, which the author named as “the living laboratory”, have shown strong evidence for the central role of environment and lifestyle which modify the human microbiome, immune balance, and thus allergy and asthma risk. Diversity of the human microbiome as well as the diversity of the natural environment that we live in and more contact with the nature are important determinants of physical health.Grant et al. (9) have focused on the influence of urban exposures on childhood asthma. The authors have meticulously summarized and analyzed the results of previous studies which aimed to investigate the interaction between indoor allergens, microbes, indoor and outdoor pollutants, social determinants and childhood asthma along with the opportunities for intervention. Multiple environmental exposures and influences contribute to the increased incidence of asthma and excess asthma morbidity among children with asthma living in urban communities. Indoor pest allergen and mold exposures have been repeatedly linked to increased asthma diagnosis, symptoms, and exacerbations in urban children. However, studies in high-risk urban populations also found that early life pest allergen exposure, along with microbial and endotoxin exposure may be associated with a decreased risk of wheezing and asthma suggesting that the association is more complex than previously thought.Since asthma prevalence varies widely depending on the socio-economical level, changes to help reduce inequities and inequalities in social determinants of health such as poverty, housing disrepair, higher rates of obesity, and chronic stress may produce positive effects at the population-level.Hernandez-Pacheco et al (10) have reviewed the latest gene-environment interaction (GxE) studies in childhood asthma. They have summarized the role of various environmental exposures and the current state of knowledge on asthma genetics. The field of GxE in asthma has drastically evolved together with technological advances over the last years. However, despite reports on the effect of numerous environmental factors on childhood asthma, the availability of detailed and diverse exposure data is limited. Tobacco smoke remains to be the most accessible and extensively explored factor followed by traffic-related air pollution in GxE studies.Airway epithelium seems to be central in gene-environment interactions. The effect of the exposure to certain environmental factors early in life on the modification of the risk and severity of asthma later in childhood is partially dependent on the functionality and integrity of the airway epithelium. It is known that the environmental exposures can trigger an inflammatory response and the disruption of the barrier and mucociliary function.Although there are several methodological and conceptual challenges with GxE interaction studies, recent data have led to new insights into childhood asthma pathophysiology which is best exemplified by the 17q12-21 asthma locus. Some of the SNPs at this locus seem to be associated with the onset of childhood asthma, thereby highlighting the importance of age related factors in gene environment interactions.The need for longitudinal and functional studies which provide insights into the biological mechanisms underlying the observed associations between environmental exposures and epigenetic changes that modify the asthma risk is highlighted.Another extensively studied environmental factor that is associated with childhood as is the so called “farm effect”. Frei et al. (11) have summarized the current knowledge on how “farm effect” influences the immune homeostasis during the intrauterine period and in childhood with a focus on immune mechanisms induced by environmental microbial diversity and microbial components. Farming lifestyle factors including nutrition influence the immune homeostasis either by regulating the innate immune system or by induction of regulatory T cells or TH1. We see diversity as a significant factor also in the farm effect. Diversity of environmental microbes, the diversity of the gut microbiome, or the diversity of the nutrition emerge as significant factors.Paciencia et al. (12) investigated the association and mechanisms between air pollution and asthma in children along with the precautions that should be taken to reduce the burden of air pollution on asthma. Environmental conditions are not shared equally across the populations, regions, and settings where people live, work, and spend their time. Urban conditions and air quality are not only important features for national and local authorities to shape healthy cities and protect their citizens from environmental and health risks, but they also provide opportunities to mitigate inequalities in the most deprived areas where the environmental burden is highest. Actions to avoid exposure to indoor and outdoor air pollutants should be complementary at different levels –individual, local, and national levels – to take strong measures to protect children.Taken together, these reviews provide a very comprehensive coverage on the role of environmental factors on childhood asthma and suggest that efforts to modify these factors may have beneficial effects not only on the individual level but also at the population level.S. Tolga Yavuz1Ömer Kalayci2Philippe A. Eigenmann3

Research data derived from observational studies are accumulating quickly in the field of allergy and immunology and a large amount of observational studies are published every year. The aim of the present study was to evaluate the adherence to the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) checklist by papers published in the three European Academy of Allergy and Clinical Immunology journals, during the period 2009-2018. To this end, we conducted a bibliographic study of up to eight randomly selected papers per year per Journal. Our literature search resulted in 223 papers. Among those, 80, 80 and 63 records were from Pediatric Allergy and Immunology, Allergy and Clinical and Translational Allergy, respectively; the latter was published only from 2011 on. Prospective, case-control, and cross-sectional designs were described in 88, 43, and 92 papers, respectively. Full reporting of all STROBE items was present in 47.4%, 45.6%, and 41.2% for the cohort, cross-sectional, and case-control studies, respectively. Generally, no time trend in adherence of reporting STROBE items was observed, apart from reporting funding, which increased from 60% in 2009/2010 to more than 90% in 2018. We identified a cluster of STROBE items with low proportions of full reporting constituted by the items on reporting study design in the title and methods, variables types along with their measurement/assessment, bias and confounding, study size, and grouping of variables. It appears that the STROBE checklist is a suitable tool in observational allergy epidemiology. However, adherence to the STROBE checklist appeared suboptimal.