To study the mechanisms and kinetics underlying the development of increased airway responsiveness (AR) after allergic sensitization, animal models have been invaluable. Using barometric whole-body plethysmography and increases in enhanced pause (Penh) as an index of airway obstruction, we measured responses to inhaled methacholine in conscious, unrestrained mice after sensitization and airway challenge with ovalbumin (OVA). Sensitized and challenged animals had significantly increased AR to aerosolized methacholine compared with control animals. AR measured as Penh was associated with increased IgE production and eosinophil lung infiltration. In a separate approach we confirmed the involvement of the lower airways in the response to aerosolized methacholine using tracheotomized mice. Increases in Penh values after methacholine challenge were also correlated with increased intrapleural pressure, measured via an esophageal tube. Lastly, mice demonstrating AR using a noninvasive technique also demonstrated increased pulmonary resistance responses to aerosolized methacholine when measured using an invasive technique the following day in the same animals. The increases in Penh values were inhibited by pretreatment of the mice with a beta 2-agonist. These data indicate that measurement of AR to inhaled methacholine by barometric whole-body plethysmography is a valid indicator of airway hyperresponsiveness after allergic sensitization in mice. The measurement of AR in unrestrained, conscious animals provides new opportunities to evaluate the mechanisms and kinetics underlying the development and maintenance of airway hyperresponsiveness and to assess various therapeutic interventions.

drawn on data from a systematic review of the literature, more recent published studies and multistakeholder expert clinical opinion. This Guideline is aimed at healthcare professionals who are encouraged to take the recommendations into account in the context of delivering clinical care. This Guideline is not a substitute for professional clinical judgment, which professionals need to exercise in the context of delivering personalised healthcare. AbstractAllergic rhinoconjunctivitis (AR) is an allergic disorder of the nose and eyes affecting about a fifth of the general population. Symptoms of AR can be controlled with allergen avoidance measures and pharmacotherapy. However, many patients continue to have ongoing symptoms and an impaired quality of life; pharmacotherapy may also induce some side-effects. Allergen immunotherapy (AIT) represents the only currently available treatment that targets the underlying pathophysiology, and it may have a disease-modifying effect. Either the subcutaneous (SCIT) or sublingual (SLIT) routes may be used. This Guideline has been prepared by the European Academy of Allergy and Clinical Immunology's (EAACI) Taskforce on AIT for AR and is part of the EAACI presidential project "EAACI Guidelines on Allergen Immunotherapy." It aims to provide evidence-based clinical recommendations and has been informed by a formal systematic review and meta-analysis. Its generation has followed the Appraisal of Guidelines for Research and Evaluation (AGREE II) approach.The process included involvement of the full range of stakeholders. In general, broad evidence for the clinical efficacy of AIT for AR exists but a product-specific evaluation of evidence is recommended. In general, SCIT and SLIT are recommended for both seasonal and perennial AR for its short-term benefit. The strongest evidence for long-term benefit is documented for grass AIT (especially for the grass 766 | ROBERTS, PFAAR ET AL. tablets) where long-term benefit is seen. To achieve long-term efficacy, it is recommended that a minimum of 3 years of therapy is used. Many gaps in the evidence base exist, particularly around long-term benefit and use in children. | ME TH ODOLOGYThis Guideline was produced using the Appraisal of Guidelines forResearch & Evaluation (AGREE II) approach, 17,18 a structured approach to guideline production (see Table S1). This is designed to ensure appropriate representation of the full range of stakeholders, a careful search for and critical appraisal of the relevant literature, a systematic approach to the formulation and presentation of recommendations and steps to ensure that the risk of bias is minimized at each step of the process. The process started on April 2015 beginning with detailed face-to-face discussions agreeing on the process and the key clinical areas to address, followed by face-to-face meetings, and regular web conferences in which professional and lay representatives participated. | Clarifying the scope and purpose of the guidelinesThe scope of this EAACI Guideline is multifaceted...

This update and revision of the international guideline for urticaria was developed following the methods recommended by Cochrane and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) working group. It is a joint initiative of the Dermatology Section of the European Academy of Allergology and Clinical Immunology (EAACI), the Global Allergy and Asthma European Network (GA²LEN) and its Urticaria and Angioedema Centers of Reference and Excellence (UCAREs and ACAREs), the European Dermatology Forum (EDF; EuroGuiDerm), and the Asia Pacific Association of Allergy, Asthma and Clinical Immunology with the participation of 64 delegates of 50 national and international societies and from 31 countries. The consensus conference was held on 3 December 2020. This guideline was acknowledged and accepted by the European Union of Medical Specialists (UEMS). Urticaria is a frequent, mast cell–driven disease that presents with wheals, angioedema, or both. The lifetime prevalence for acute urticaria is approximately 20%. Chronic spontaneous or inducible urticaria is disabling, impairs quality of life, and affects performance at work and school. This updated version of the international guideline for urticaria covers the definition and classification of urticaria and outlines expert‐guided and evidence‐based diagnostic and therapeutic approaches for the different subtypes of urticaria.

Background The European Academy of Allergy and Clinical Immunology (EAACI) is in the process of developing Guidelines on Allergen Immunotherapy (AIT) for Allergic Rhinoconjunctivitis. To inform the development of clinical recommendations, we undertook a systematic review to assess the effectiveness, cost‐effectiveness, and safety of AIT in the management of allergic rhinoconjunctivitis. Methods We searched nine international biomedical databases for published, in‐progress, and unpublished evidence. Studies were independently screened by two reviewers against predefined eligibility criteria and critically appraised using established instruments. Our primary outcomes of interest were symptom, medication, and combined symptom and medication scores. Secondary outcomes of interest included cost‐effectiveness and safety. Data were descriptively summarized and then quantitatively synthesized using random‐effects meta‐analyses. Results We identified 5960 studies of which 160 studies satisfied our eligibility criteria. There was a substantial body of evidence demonstrating significant reductions in standardized mean differences (SMD) of symptom (SMD −0.53, 95% CI −0.63, −0.42), medication (SMD −0.37, 95% CI −0.49, −0.26), and combined symptom and medication (SMD −0.49, 95% CI −0.69, −0.30) scores while on treatment that were robust to prespecified sensitivity analyses. There was in comparison a more modest body of evidence on effectiveness post‐discontinuation of AIT, suggesting a benefit in relation to symptom scores. Conclusions AIT is effective in improving symptom, medication, and combined symptom and medication scores in patients with allergic rhinoconjunctivitis while on treatment, and there is some evidence suggesting that these benefits are maintained in relation to symptom scores after discontinuation of therapy.

Mast cells are the main effector cells of immediate hypersensitivity and anaphylaxis. Their role in the development of allergen-induced airway hyperresponsiveness (AHR) is controversial and based on indirect evidence. To address these issues, mast cell–deficient mice (W/W  v) and their congenic littermates were sensitized to ovalbumin (OVA) by intraperitoneal injection and subsequently challenged with OVA via the airways. Comparison of OVA-specific immunoglobulin E (IgE) levels in the serum and numbers of eosinophils in bronchoalveolar lavage fluid or lung digests showed no differences between the two groups of mice. Further, measurements of airway resistance and dynamic compliance at baseline and after inhalation of methacholine were similar. These data indicate that mast cells or IgE–mast cell activation is not required for the development of eosinophilic inflammation and AHR in mice sensitized to allergen via the intraperitoneal route and challenged via the airways.

Summary There is a growing consensus that the long term solution to the asthma epidemic lies in prevention and not in treatment of established disease. Atopic asthma arises from gene x environment interactions which most commonly occur during a relatively narrow window period in pre- and postnatal development. These interactions are incompletely understood, and hence the holy grail of primary prevention remains an elusive goal. We contend that a lack of understanding of the role of atopy in early life in the development of persistent asthma in children exists amongst primary care physicians, paediatricians and specialists. In this review we argue that early identification of high risk children is feasible based on currently available technology, and worthwhile in relation to potential benefits to the children so identified. Knowledge of an asthmatic child's atopic status in early life has practical clinical and prognostic implications, as well as forming the basis for future preventative strategies.

Viral respiratory infections can predispose to the development of asthma by mechanisms that are presently undetermined. Using a murine model of respiratory syncytial virus (RSV) infection, acute infection is associated with airway hyperresponsiveness as well as enhanced responses to subsequent sensitization to allergen. We demonstrate that acute viral infection results in increased airway responsiveness to inhaled methacholine and pulmonary neutrophilic and eosinophilic inflammation. This response is associated with predominant production of Th-1-type cytokines in peribronchial lymph node cells in vitro. Mice sensitized to ovalbumin via the airways after RSV infection developed increased airway responsiveness to methacholine and pulmonary eosinophilic and neutrophilic inflammation, associated with the predominant production of Th-2-type cytokines.

The results of this study are supportive for a role of the microbiota in the development of AD. Moreover, the "beneficial" influence of older siblings on the microbiota composition suggests that this microbiota may be one of the biological mechanisms underlying the sibling effect.