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Chronic spontaneous urticaria (CSU) is a debilitating skin disease characterized by intensely itchy wheals, angioedema, or both. Symptoms recur spontaneously, on a near‐daily basis, over >6 weeks; many patients experience flare‐ups over several years and, consequently, reduced quality of life. Differences between the inflammatory profiles of the skin of CSU patients (wheals and nonlesional sites) and healthy controls indicate that key drivers such as mast cells, eosinophils, and basophils interact, release vasoactive mediators, and prime the skin, leaving patients predisposed to symptoms. Many cytokines and chemokines involved in these inflammatory networks and their corresponding intracellular signaling cascades have been identified. These insights informed the development of therapies such as omalizumab, dupilumab, and Bruton's tyrosine kinase (BTK) inhibitors, marking a renewed focus on pathogenesis in CSU clinical research. Despite progress, current therapies provide symptomatic control but do not appear to redress the inflammatory balance in the skin permanently. A deeper understanding of CSU pathogenesis will permit a more targeted approach to developing novel treatments with curative intent. Here, we review what is known about the pathogenesis of CSU and consider how this can be used to identify rational targets to improve patient care further. [ABSTRACT FROM AUTHOR]

Background: Ligelizumab, a next‐generation, humanized anti‐immunoglobulin E (IgE) monoclonal antibody is in development as a treatment for patients with chronic spontaneous urticaria, whose symptoms are inadequately controlled with standard‐of‐care therapy. Objective: To evaluate the long‐term safety and re‐treatment efficacy of ligelizumab 240 mg in patients who completed the core study and extension study. Methods: This open‐label, single‐arm, long‐term Phase 2b extension study was designed to assess patients who were previously administered various doses of ligelizumab, omalizumab or placebo in the Phase 2b, dose‐finding core study and who presented with active disease after Week 32. In the extension study, patients received ligelizumab 240 mg subcutaneously every 4 weeks, for 52 weeks and were monitored post‐treatment for 48 weeks. Results: Overall, ligelizumab was well‐tolerated with no newly identified safety signals. A total of 95.4% (226/237) screened patients received ligelizumab 240 mg in the extension study; 84.1% (190/226) of patients experienced at least one treatment‐emergent adverse event. Most reported events were mild (41.6%) or moderate (35.8%) and mostly unrelated to the study treatment. At Week 12, 46.5% of patients had a complete response increasing to 53.1% after 52 weeks. Following 52 weeks of extension study treatment, 75.8% (95% confidence interval, 69.9, 81.3) of patients had cumulative complete responses. The median time to relapse in complete responders was 38 weeks. Conclusion: The long‐term safety profile of ligelizumab 240 mg in patients with chronic spontaneous urticaria was consistent with the core study and re‐treatment efficacy was shown. Trial Registration: ClinicalTrials.gov Identifier: NCT02477332 and NCT02649218. [ABSTRACT FROM AUTHOR]

To the Editor, The involvement of the coagulation cascade has been demonstrated in the pathogenesis of chronic spontaneous urticaria (CSU) by a number of observations, including successful treatment of CSU with anticoagulants.[[1]] We previously reported that blood coagulation potential is elevated in CSU and that histamine and agonists for toll-like receptors (TLRs) may synergistically induce tissue factor (TF) expression on vascular endothelial cells.[[3]] Immunohistochemical staining revealed TF expression by eosinophils in the lesion of CSU.[5] However, monocytes are considered to be the main source of TF in the blood, causing clot formation.[6] We here investigated the level of TF expression on monocytes in the blood of patients with CSU, and the potential of TF on monocytes to trigger the extrinsic coagulation cascade and consequential inter-cellular gap formation of vascular endothelial cells. To test whether the LPS-induced TF of monocytes has a procoagulant activity, monocytes isolated from normal donors were stimulated with LPS and measured for their TF activity. Since the activation of TLRs transduces various cascades of the cells, other stimuli that share intracellular signal transductions with TLRs that induce monocyte TF expression may also contribute to the histamine-resistant or partially resistant CSU. [Extracted from the article]

Background: Staphylococcus aureus (S. aureus) is frequently detected in the skin of patients with atopic dermatitis (AD), and involved in the flare of AD. There are some evidence‐specific strains of S. aureus affect the severity of AD. However, the mechanism of predominant colonization and the aggravation of dermatitis by certain strains of S. aureus in the patients with AD are still unknown. Objective: To reveal the characteristics of S. aureus from patients with AD (S. aureus‐AD), we analyzed the interaction of S. aureus‐AD and keratinocytes in comparison with those of S. aureus laboratory strains (S. aureus‐stand.). Methods: We stimulated HaCaT cells, keratinocyte cell line, and human epidermal keratinocytes by heat‐killed S. aureus strains, then evaluated immune response of keratinocytes by ELISA, immunofluorescence staining, and flow cytometry. Results: Upon incubation with keratinocytes, three out of four strains of heat‐killed S. aureus‐AD were strongly agglutinated inside the cytoplasm. In the cells, they are located in lysosomes and promoted the secretion of interleukin‐1α (IL‐1α). These reactions were not observed by any of four strains of S. aureus‐stand. and S. epidermidis and were abolished by the treatment of S. aureus with proteinase K. Moreover, the IL‐1α secretion was diminished by the inhibition of Toll‐like receptor 9 (TLR9). Conclusion: S. aureus‐AD accumulates in lysosome of keratinocytes by means of bacterial cell wall proteins and induces IL‐1α via TLR9. Compared to standard S. aureus strains, S. aureus isolated from AD skin are able to induce different innate immune responses. S. aureus from AD skin are internalized into keratinocytes and accumulate in lysosomes with inducing IL‐1α secretion via TLR9. Specific surface proteins of S. aureus from AD skin are responsible for their internalization. [ABSTRACT FROM AUTHOR]

Background: Food anaphylaxis is commonly elicited by unintentional ingestion of foods containing the allergen above the tolerance threshold level of the individual. While labeling the 14 main allergens used as ingredients in food products is mandatory in the EU, there is no legal definition of declaring potential contaminants. Precautionary allergen labeling such as "may contain traces of" is often used. However, this is unsatisfactory for consumers as they get no information if the contamination is below their personal threshold. In discussions with the food industry and technologists, it was suggested to use a voluntary declaration indicating that all declared contaminants are below a threshold of 0.5 mg protein per 100 g of food. This concentration is known to be below the threshold of most patients, and it can be technically guaranteed in most food production. However, it was also important to assess that in case of accidental ingestion of contaminants below this threshold by highly allergic patients, no fatal anaphylactic reaction could occur. Therefore, we performed a systematic review to assess whether a fatal reaction to 5mg of protein or less has been reported, assuming that a maximum portion size of 1kg of a processed food exceeds any meal and thus gives a sufficient safety margin., Methods: MEDLINE and EMBASE were searched until 24 January 2021 for provocation studies and case reports in which one of the 14 major food allergens was reported to elicit fatal or life-threatening anaphylactic reactions and assessed if these occurred below the ingestion of 5mg of protein. A Delphi process was performed to obtain an expert consensus on the results., Results: In the 210 studies included, in our search, no reports of fatal anaphylactic reactions reported below 5 mg protein ingested were identified. However, in provocation studies and case reports, severe reactions below 5 mg were reported for the following allergens: eggs, fish, lupin, milk, nuts, peanuts, soy, and sesame seeds., Conclusion: Based on the literature studied for this review, it can be stated that cross-contamination of the 14 major food allergens below 0.5 mg/100 g is likely not to endanger most food allergic patients when a standard portion of food is consumed. We propose to use the statement "this product contains the named allergens in the list of ingredients, it may contain traces of other contaminations (to be named, e.g. nut) at concentrations less than 0.5 mg per 100 g of this product" for a voluntary declaration on processed food packages. This level of avoidance of cross-contaminations can be achieved technically for most processed foods, and the statement would be a clear and helpful message to the consumers. However, it is clearly acknowledged that a voluntary declaration is only a first step to a legally binding solution. For this, further research on threshold levels is encouraged., (© 2021 The Authors. Allergy published by European Academy of Allergy and Clinical Immunology and John Wiley & Sons Ltd.)

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., (© 2021 GA²LEN. Allergy published by European Academy of Allergy and Clinical Immunology and John Wiley & Sons Ltd.)

Background: With no approved treatments in Japan for the prevention of hereditary angioedema (HAE) attacks, there is a significant unmet need for long-term prophylactic therapies for Japanese patients with HAE. Berotralstat (BCX7353) is an oral, once-daily, highly selective inhibitor of plasma kallikrein in development for prophylaxis of angioedema attacks in HAE patients., Methods: APeX-J is a phase 3, randomized, double-blind, placebo-controlled, parallel-group, 3-part trial conducted in Japan (University Hospital Medical Information Network identifier, UMIN000034869; ClinicalTrials.gov identifier, NCT03873116). Patients with a clinical diagnosis of type 1 or 2 HAE underwent a prospective run-in period of 56 days to determine eligibility, allowing enrollment of those with ≥2 expert-confirmed angioedema attacks. Patients were randomly assigned (1:1:1) and stratified by baseline attack rate (≥2 vs. <2 expert-confirmed attacks/month between screening and randomization) to receive once-daily berotralstat 110 mg, berotralstat 150 mg, or placebo. The primary endpoint was the rate of expert-confirmed angioedema attacks during dosing in the 24-week treatment period., Results: Nineteen patients were randomized to receive once-daily berotralstat 110 mg (n = 6), berotralstat 150 mg (n = 7), or placebo (n = 6). Treatment with berotralstat 150 mg significantly reduced HAE attacks relative to placebo (1.11 vs. 2.18 attacks/month, p = .003). The most frequently reported treatment-emergent adverse events (TEAEs) in berotralstat-treated patients (n = 13) were nasopharyngitis (n = 4, 31%), abdominal pain, cough, diarrhea, and pyrexia (n = 2 each, 15%)., Conclusions: Orally administered, once-daily berotralstat 150 mg significantly reduced the frequency of HAE attacks and was safe and well tolerated, supporting its use as a prophylactic therapy in patients with type 1 or 2 HAE in Japan., (© 2020 The Authors. Allergy published by European Academy of Allergy and Clinical Immunology and John Wiley & Sons Ltd.)