Mas-related G protein-coupled receptor X2 and its activators in dermatologic allergies.

The Mas-related G protein-coupled receptor X2 (MRGPRX2) is a multiligand receptor responding to various exogenous and endogenous stimuli. Being highly expressed on skin mast cells, MRGPRX2 triggers their degranulation and release of proinflammatory mediators, and it promotes multicellular signaling cascades, such as itch induction and transmission in sensory neurons. The expression of MRGPRX2 by skin mast cells and the levels of the MRGPRX2 agonists (eg, substance P, major basic protein, eosinophil peroxidase) are upregulated in the serum and/or skin of patients with inflammatory and pruritic skin diseases, such as chronic spontaneous urticaria or atopic dermatitis. Therefore, MRGPRX2 and its agonists might be potential biomarkers for the progression of cutaneous inflammatory diseases and the response to treatment. In addition, they may represent promising targets for prevention and treatment of signs and symptoms in patients with skin diseases or drug reactions. To assess this possibility, this review explores the role and relevance of MRGPRX2 and its activators in cutaneous inflammatory disorders and chronic pruritus.

Predictors of treatment response in chronic spontaneous urticaria.

The current therapeutic algorithm for chronic spontaneous urticaria (CSU), endorsed by the international guideline, entails treatment escalation from second-generation H1 -antihistamines (sgAHs) to omalizumab and cyclosporine until complete response is achieved. Recently, several predictors of response to these treatment options have been described. Here, we discuss the most promising predictors of response and nonresponse to these treatments in CSU. A systematic search was performed by two independent researchers using the MEDLINE/PubMed database with specific keywords and 73 studies included in the review. Levels of evidence were categorized as strong (robust predictors), weak (emerging predictors) or no association, based on the outcome and number of studies available. High disease activity, high levels of C-reactive protein and D-dimer are robust predictors for a poor or no response to sgAHs. Poor or no response to omalizumab is robustly predicted by low serum levels of total IgE. A good response to cyclosporine is robustly predicted by a positive basophil histamine release assay, whereas low total IgE is an emerging predictor. The response to treatment with sgAHs, omalizumab and cyclosporine can be predicted by the use of markers that are readily available in routine clinical practice. Further studies are needed to confirm these predictors.

The role of eosinophils in chronic spontaneous urticaria.

Chronic spontaneous urticaria (CSU) is considered to be primarily a mast cell-driven disease. However, recent evidence suggests that eosinophils may also have an axial role in symptomology. Histologic studies have demonstrated the presence of both eosinophils and eosinophil granules, indicative of activation, in CSU lesions. Although many allergic and inflammatory conditions are associated with a peripheral blood eosinophilia, the converse appears to be the case in CSU, with a peripheral blood eosinopenia being observed in many patients. Possible mechanisms include the depletion of blood eosinophils by recruitment into the skin during active disease and immunologic destruction in the blood. We also address in some detail the interactions between eosinophils and mast cells, particularly the cytokine cross-talk of these cells and mediator release possibly leading to clinical symptoms. Also, activation by eosinophil proteins of the coagulation pathway leads to the generation of thrombin and increased mast cell degranulation. Finally, treatments aimed at reducing eosinophil accumulation and activation, such as the anti-IL-5 antibodies mepolizumab, reslizumab, and benralizumab, have been reported to reduce CSU symptoms. Clearly, a new picture of an important role of eosinophils in the pathogenesis of CSU is emerging.

Angioedema Masqueraders.

Angioedema is a common reason for referral to immunology and allergy specialists. Not all cases are in fact angioedema. There are many conditions that may mimic its appearance, resulting in misdiagnosis. This may happen when a clinician is unfamiliar with conditions resembling angioedema or when there is a low index of clinical suspicion. In this article, we explore a list of differential diagnoses based on body parts, including the lips, the limbs, periorbital tissues, the face, epiglottis and uvula, as well as the genitalia, that may pose as a masquerader even to an experienced eye.

Case report of an unusual allergic reaction to a routine skin prick test performed in an outpatient clinic: Diagnosis, management, and knowledge gaps.

BACKGROUND: The skin prick test (SPT) is a standard procedure in allergy/immunology clinics, crucial for evaluating conditions like allergic rhinitis and food allergies. As a cornerstone in investigating immunoglobulin E-mediated allergy, it plays a vital role in diagnosing allergies, including those triggered by common dust mites like Dermatophagoides pteronyssinus, Dermatophagoides farinae, Euroglyphus maynei, and Blomia tropicalis. Despite its widespread use, adverse reactions to SPT are uncommon (15 per 100,000 patients), though the procedure is not entirely risk-free. This article presents a clinical case involving a 17-year-old female who experienced a moderately delayed allergic reaction 120 minutes post-SPT, managed effectively with subsequent symptom resolution. METHODS: The patient, with a history of persistent rhinorrhea, itchy nose, eyes, and postnasal drip, sought consultation due to worsening symptoms. Diagnostic measures, including patient-reported outcomes and SPT with a standard aeroallergen panel, revealed sensitization to various allergens. RESULTS: Post-test, the patient reported ocular pruritus, left eyelid swelling, and moderate rhinorrhea, persisting for about 24 hours. On the subsequent medical visit, the patient received rupatadine and deflazacort, leading to symptom resolution within 3 hours. CONCLUSION: This article delves into a systemic allergic reaction post-SPT, emphasizing the 2 main stages of type I hypersensitivity reactions. While the acute phase involves mast cell-driven mediators within 15 minutes, the delayed phase (4-8 hours) includes de novo cytokine release. Vigilance regarding symptom onset and differentiation between mild and severe reactions is crucial. Notably, the absence of specific waiting time guidelines post-SPT underscores the need for reporting to enhance understanding and subsequent management. Performing these procedures in specialized centers with qualified professionals is essential for effectively managing potential anaphylactic reactions. Addressing these knowledge gaps will contribute to enhanced patient safety during diagnostic procedures.

An update on the use of antihistamines in managing chronic urticaria.

INTRODUCTION: Urticaria, a mast cell-mediated skin disease, manifests as acute or chronic, with the latter divided into spontaneous and inducible types and requires individualized management, including identifying triggers and comorbidities. Antihistamines, particularly the second generation group, form the mainstay of primary treatment plans consisting of dosage adjustments and/or in combination with other treatment modalities depending on underlying disease control. AREAS COVERED: A literature search was conducted using 'antihistamines,' 'urticaria,' 'pharmacogenomics,' 'genomics,' 'biomarkers' and 'treatment response' as key words. In this review, we focus on the comprehensive understanding and application of antihistamines in managing adult and adolescent patients with chronic urticaria. EXPERT OPINION: Using antihistamines to treat urticaria is set to change significantly, focusing more on personalized medicine and identifying key biomarkers to enhance treatment response prediction. These changes aim to make treatments more specific and cost-effective by avoiding unnecessary tests. Applying new approaches in everyday clinical care faces challenges like proving the biomarkers' reliability, updating current guidelines, and incorporating individualized treatments into standard procedures. Efforts should now concentrate on finding easy-to-use biomarkers, improving access to pharmacogenomics, understanding why some patients are resistant to treatment, and creating more specific treatment options based on patient needs.

Urticaria and mimickers of urticaria.

Urticaria is a common skin condition encountered across various specialties in medicine, especially in dermatology and allergy/immunology practice. It has a heterogeneous presentation hence it is unsurprising that many skin conditions may be confused with urticaria. Urticaria may present as acute or chronic urticaria, the latter can be further categorised into chronic spontaneous and chronic inducible. In this article, we explore, explain, and summarise various skin lesions that are considered mimickers of urticaria, to promote understanding of each of the conditions highlighted, improve recognition, and reduce misdiagnosis.

Luftsichel sign.

Here we present a case of a patient with breathlessness and cough admitted to the COVID ward. Chest radiography demonstrates findings consistent with lobar collapse, giving rise to the 'Luftsichel sign'. This sign has been described in the literature and highlights the importance of recognition and prompt further investigation.

Epidemiology, Management, and Treatment Access of Hereditary Angioedema in the Asia Pacific Region: Outcomes From an International Survey.

BACKGROUND: Hereditary angioedema (HAE) is a rare genetic disease with significant morbidity and mortality for which early diagnosis and effective therapy are critical. Many Asia Pacific (AP) countries still lack access to diagnostic tests and evidence-based therapies. Epidemiologic data from the AP is needed to formulate regional guidelines to improve standards of care for HAE. OBJECTIVE: To investigate the estimated minimal prevalence, needs, and potential interventions for the diagnosis and management of HAE in the AP. METHODS: A structured questionnaire was distributed to representative experts from member societies of the Asia Pacific Association of Allergy, Asthma and Clinical Immunology. Patient profiles and the presence of diagnostic facilities or tests, regional and national HAE guidelines, and patient support groups were reported and compared. RESULTS: Completed questionnaires were received from 14 representatives of 12 member countries and territories, representing 46% of the world population. Overall minimal prevalence of HAE in the AP region was 0.02/100,000 population, with significant heterogeneity across different centers. Only one-half and one-third had registered on-demand and prophylactic medications, respectively. Few had patient support groups (58%) or regional guidelines (33%), and their existence was associated with the availability of HAE-specific medications. Availability of C1-inhibitor level testing was associated with a lower age at HAE diagnosis (P = .017). CONCLUSIONS: Hereditary angioedema in the AP differs from that in Western countries. Hereditary angioedema-specific medications were registered in only a minority of countries and territories, but those with patient support groups or regional guidelines were more likely to have better access. Asia Pacific-specific consensus and guidelines are lacking and urgently needed.

The Melbourne epidemic thunderstorm asthma event 2016: a 5-year longitudinal study.

Background: In 2016, Melbourne was struck by the world's largest and most devastating epidemic thunderstorm asthma (ETSA) episode. While affected individuals displayed worsened short-term asthma control, little is known about their longer-term natural history, nor about interventions that restore control. Objective: We assessed the asthma symptomatology and related behaviours of ETSA-affected individuals through a single-centre prospective 5-year longitudinal study. We embedded an open-label observational trial investigating the role of grass pollen sublingual tablet (Oralair) allergen immunotherapy in improving asthma and allergic rhinitis symptoms. Methods: Allergic rhinitis symptom severity, frequency of asthma symptoms and inhaled corticosteroid usage were assessed via questionnaire yearly. In 2018, a subgroup of participants was enrolled in an observational study of Oralair treatment compared to control. The active group received Oralair from 2019 to 2021; both groups were followed-up for 5 years. Subgroup analyses were performed for participants with complete datasets, and who completed the trial per-protocol. Results: Year-on-year data across 5 years was available for 30 participants. The rate of persistent asthma symptoms declined from 37% to 7% in 2016 to 2021. Only 10%-27% of participants reported being completely asymptomatic in any given year. The inhaled preventer prescription rate was 67%, with only 35% being adherent. Twenty-seven participants with available data completed the Oralair trial per-protocol. No significant difference was noted between control and active groups for allergic rhinitis symptoms or asthma control, although the Oralair group saw a significant improvement in asthma control comparing 2019 with 2021. Conclusion: This is the longest documented follow-up of ETSA-affected individuals. Five years following sentinel event, there was progressive reduction but some persistence in asthma symptoms. Oralair allergen immunotherapy did not further improve allergic rhinitis or asthma symptoms compared to control, but there were no further ETSA events to test a protective effect during the study period.

Mast Cell Diseases in Practice and Research: Issues and Perspectives Raised by Patients and Their Recommendations to the Scientific Community and Beyond.

BACKGROUND: Since 2010, patients and physicians have collaborated to understand unmet needs of patients with mast cell diseases, incorporating mastocytosis and mast cell activation disorders, which include mast cell activation syndromes. OBJECTIVE: This Open Innovation in Science project aims to expand understanding of the needs of patients affected by mast cell diseases, and encourage global communication among patient advocacy groups, physicians, researchers, industry, and government. A major aim is to support the scientific community's efforts to improve diagnosis, management, therapy, and patients' quality of life by addressing unmet needs. METHODS: In collaboration with mast cell disease specialists, 13 patient advocacy groups from 12 countries and regions developed lists of top patient needs. A core team of leaders from patient advocacy groups collected and analyzed the data and proposed possible actions to address patient needs. RESULTS: Findings identified similarities and differences among participating countries in unmet needs between patients with mastocytosis and those with mast cell activation syndromes. Issues emphasized struggles relating to the nature and rarity of mast cell diseases, their impact on quality of life, the diagnostic process, access to appropriate care, more effective treatment, and the need for research. CONCLUSIONS: Solutions vary across countries because situations differ, in particular regarding the existence of and access to centers of excellence and reference centers. Multifaceted mast cell activation syndrome barriers necessitate innovative approaches to improve access to appropriate care. The outcomes of this project should greatly support scientists and clinicians in their efforts to improve diagnosis, management, and treatment of patients with mastocytosis and mast cell activation disorders.

Total IgE as a Marker for Chronic Spontaneous Urticaria.

OBJECTIVE: Immunoglobulin E (IgE) and its receptor, FcɛRI, importantly contribute to the pathophysiology of chronic spontaneous urticaria (CSU). Recent findings point to a possible role of total IgE as a marker of CSU disease activity, endotypes, and responses to treatment. The evidence in support of total IgE included in the diagnostic workup of patients with CSU has not yet been reviewed. METHODS: Publications were searched via PubMed. The search terms used were "chronic urticaria" and "total IgE." Studies were screened by titles and abstracts, and 141 were used in the review. RESULTS: CSU patients frequently had elevated total IgE serum levels (up to 50%), but normal or very low total IgE levels also occurred. High total IgE may represent high disease activity, longer disease duration, high chance of responding to omalizumab treatment, quick relapse after stopping omalizumab, and lower chance of responding to cyclosporine. Low IgE, in contrast, may suggest Type IIb autoimmune CSU, poor response to treatment with omalizumab and a better chance to benefits from cyclosporine treatment. Furthermore, IgE in different CSU cohorts may have different physicochemical properties that could explain differences in treatment responses to IgE-directed therapies. CONCLUSION: The results of our review suggest that total IgE is a valuable marker for CSU, and we recommend its assessment in the routine diagnostic workup of CSU patients.

The Diagnostic Workup in Chronic Spontaneous Urticaria-What to Test and Why.

BACKGROUND: In chronic spontaneous urticaria (CSU), the guidelines recommend very limited diagnostic procedures during the routine workup, although additional investigations might be indicated in some patients with CSU. For physicians treating patients with CSU, it is often difficult to decide which diagnostic tests are useful. OBJECTIVE: To provide recommendations on what diagnostic tests should be performed on which patients with CSU. METHODS: We performed an extensive literature search on the respective topics and identified relevant questions that should prompt diagnostic procedures based on the published evidence and expert consensus among all authors. RESULTS: We provide questions, diagnostic testing, where appropriate, and recommendation that should be included when assessing the history of a patient with CSU, to explore and rule out differential diagnoses, to assess patients for underlying causes and modifying conditions, to explore patients for comorbid diseases and consequences of having CSU, and to assess patients for CSU components that can help to predict their disease course and response to treatment. CONCLUSIONS: Here, we provide physicians treating patients with CSU with information about which clues should lead to which tests and why.

Diagnostic procedures & practices in drug allergy/hypersensitivity: a survey of 13 Asian countries.

BACKGROUND: The issues and challenges in the diagnosis of drug allergy/hypersensitivity among children and adults in Asia are likely to be different from non-Asian countries. OBJECTIVE: To study the diagnostic modalities used in the evaluation and management of drug allergy/drug hypersensitivity reactions (DHRs) among member societies of the Asia Pacific Association of Allergy, Asthma and Clinical Immunology (APAAACI). METHODS: A questionnaire comprising 41 questions was circulated electronically to member societies and individual members of APAAACI between January 23, 2020 and March 6, 2020. RESULTS: Twenty-six respondents from 15 member societies and 1 individual member responded. European DHR guidelines were most commonly used. Skin prick and intradermal testing was used by 100%, with only 60% having access to commercial penicillin skin test reagents. In vitro-specific IgE tests were used by 75%, and basophil activation test by 56.3% for immediate DHR. Patch tests were used by 75% in contrast to lymphocyte transformation tests by 25% for nonimmediate DHR. Drug provocation tests were used by 68.8%, the most common indication being to exclude hypersensitivity where history/symptoms were not suggestive of drug hypersensitivity/allergy (93.3%). Human leukocyte antigen (HLA) genotype testing was mandatory among 25% respondents before new carbamazepine prescriptions, and 8.3% for allopurinol prescriptions. CONCLUSIONS: There was increased use of skin testing for iodinated contrast media hypersensitivity and patch testing for nonimmediate DHR. HLA genotype testing prior to new carbamazepine, allopurinol and abacavir prescriptions remain variable despite strong associations for severe cutaneous adverse reactions with Asian ethnicity. Results of this survey form a useful framework for developing educational and training needs and for improving access to drug allergy diagnostic and treatment modalities across APAAACI member societies.

Drug hypersensitivity reactions in Asia: regional issues and challenges.

There are geographical, regional, and ethnic differences in the phenotypes and endotypes of patients with drug hypersensitivity reactions (DHRs) in different parts of the world. In Asia, aspects of drug hypersensitivity of regional importance include IgE-mediated allergies and T-cell-mediated reactions, including severe cutaneous adverse reactions (SCARs), to beta-lactam antibiotics, antituberculous drugs, nonsteroidal anti-inflammatory drugs (NSAIDs) and radiocontrast agents. Delabeling of low-risk penicillin allergy using direct oral provocation tests without skin tests have been found to be useful where the drug plausibility of the index reaction is low. Genetic risk associations of relevance to Asia include human leucocyte antigen (HLA)-B*1502 with carbamazepine SCAR, and HLA-B*5801 with allopurinol SCAR in some Asian ethnic groups. There remains a lack of safe and accurate diagnostic tests for antituberculous drug allergy, other than relatively high-risk desensitization regimes to first-line antituberculous therapy. NSAID hypersensitivity is common among both adults and children in Asia, with regional differences in phenotype especially among adults. Low dose aspirin desensitization is an important therapeutic modality in individuals with cross-reactive NSAID hypersensitivity and coronary artery disease following percutaneous coronary intervention. Skin testing allows patients with radiocontrast media hypersensitivity to confirm the suspected agent and test for alternatives, especially when contrasted scans are needed for future monitoring of disease relapse or progression, especially cancers.

Adverse drug reaction classification by health professionals: appropriate discrimination between allergy and intolerance?

BACKGROUND: The correct classification of an adverse drug reaction (ADR) as allergy (immunological) or intolerance (non-immunological) has important clinical implications. The aim of this study was to examine the ability of health professionals to discriminate between allergy and intolerance, classify the severity of the ADR and degree of contraindication. METHODS: Health professionals were presented ten 'real-life' ADR scenarios using an online questionnaire and asked to: categorise the reaction as allergy or intolerance, rate the severity of the reaction and judge the level of contraindication of the causative drug. The number and proportion of responses were calculated for each of the cases presented and associations between classification of reaction type, severity and level of contraindication were examined. RESULTS: A total of 394 responses were received. Overall 59.0% (SD 28.9) correctly categorised the cases, 60.8% (SD 16.8) classified the severity correct, and less than half (44.7%, SD 28.6) correctly identified the level of contraindication. The proportion of health professionals correctly answering the type, severity and level of contraindication for the allergy case was significantly higher (p < 0.0001) by comparison to the intolerance cases (type: 56.6% ± 33.1; severity: 57.3 ± 11.9; level of contraindication: 38.5 ± 19.9). CONCLUSIONS: Health professionals have suboptimal understanding of classification of ADRs. Strategies are required to strictly avoid re-exposure of patients to drugs which carry an increased risk of inducing a dangerous reaction, whilst minimising the avoidance of drugs which are of minimal risk or allowing the use of low-risk drugs where the benefits may be significant.