Altered Sweat Composition Due to Changes in Tight Junction Expression of Sweat Glands in Cholinergic Urticaria Patients.

In cholinergic urticaria (CholU), small, itchy wheals are induced by exercise or passive warming and reduced sweating has been reported. Despite the described reduced muscarinic receptor expression, sweat duct obstruction, or sweat allergy, the underlying pathomechanisms are not well understood. To gain further insights, we collected skin biopsies before and after pulse-controlled ergometry and sweat after sauna provocation from CholU patients as well as healthy controls. CholU patients displayed partially severely reduced local sweating, yet total sweat volume was unaltered. However, sweat electrolyte composition was altered, with increased K+ concentration in CholU patients. Formalin-fixed, paraffin-embedded biopsies were stained to explore sweat leakage and tight junction protein expression. Dermcidin staining was not found outside the sweat glands. In the secretory coils of sweat glands, the distribution of claudin-3 and -10b as well as occludin was altered, but the zonula occludens-1 location was unchanged. In all, dermcidin and tight junction protein staining suggests an intact barrier with reduced sweat production capability in CholU patients. For future studies, an ex vivo skin model for quantification of sweat secretion was established, in which sweat secretion could be pharmacologically stimulated or blocked. This ex vivo model will be used to further investigate sweat gland function in CholU patients and decipher the underlying pathomechanism(s).

Anti-KIT antibody, barzolvolimab, reduces skin mast cells and disease activity in chronic inducible urticaria.

BACKGROUND: Chronic inducible urticaria (CIndU) is characterized by mast cell (MC)-mediated wheals in response to triggers: cold in cold urticaria (ColdU) and friction in symptomatic dermographism (SD). KIT receptor activation by stem cell factor (SCF) is essential for MC function. Barzolvolimab (CDX-0159) is a humanized antibody that inhibits KIT activation by SCF and was well tolerated in healthy volunteers with dose-dependent plasma tryptase suppression indicative of systemic mast cell ablation. METHODS: This is an open-label, trial in patients with antihistamine refractory ColdU or SD, receiving one IV dose of barzolvolimab (3 mg/kg), with a 12-week follow-up. Primary endpoint was safety/tolerability; pharmacodynamic (PD)/clinical endpoints included serum tryptase, plasma SCF, skin MC histology, provocation tests, urticaria control test (UCT), and dermatology life quality index (DLQI). RESULTS: Analysis populations were safety (n = 21) and pharmacodynamics/clinical activity (n = 20). Barzolvolimab was well tolerated; most adverse events were mild and resolved. Treatment resulted in significant depletion of skin MCs, decreased tryptase (

Chronic urticaria and the pathogenic role of mast cells.

The signs and symptoms of chronic urticaria (CU) are caused by the activation and degranulation of skin mast cells (MCs). Recent studies have added to our understanding of how and why skin MCs are involved and different in CU. Also, novel and relevant mechanisms of MC activation in CU have been identified and characterized. Finally, the use of MC-targeted and MC mediator-specific treatments has helped to better define the role of the skin environment, the contribution of specific MC mediators, and the relevance of MC crosstalk with other cells in the pathogenesis of CU. Here, we review these recent findings and their impact on our understanding of CU, with a focus on chronic spontaneous urticaria (CSU). Also, we highlight open questions, issues of controversy, and unmet needs, and we suggest what studies should be performed moving forward.

Development of the Cold Urticaria Activity Score.

BACKGROUND: Cold urticaria (ColdU) is a form of inducible urticaria where cold induces wheals and/or angioedema. The burden of disease is high and linked to trigger thresholds, exposure, and avoidance. There are presently no validated patient-reported outcome measures (PROMs) to assess and monitor disease activity. Our objective was to develop a disease-specific activity score for ColdU that is easy to administer and evaluate. METHODS: A Cold Urticaria Activity Score (ColdUAS) questionnaire was developed, directed by PROM developing guidelines. After the generation of a conceptional framework, the item generation phase included the literature research on ColdU signs and symptoms and on comparable tools for similar diseases and 47 ColdU patient interviews. Subsequently, an impact analysis for content validity was performed. The final selection of items underwent expert review for face validity and cognitive debriefing. RESULTS: The ColdUAS, a self-administered questionnaire for the prospective assessment of disease activity in patients with ColdU, consists of 4 items: 1. the frequency and severity of the signs (wheals and/or angioedema), 2. the frequency and severity of the symptoms (e.g., itch and burn), 3. the exposure to specific triggers, and 4. the avoidance of these triggers. The recall period for each item is the last 24 h. CONCLUSIONS: The ColdUAS is the first disease-specific PROM to assess ColdU disease activity. It may help to better assess patients' disease status in routine clinical practice as well as in clinical trials. Anchor-based approaches are currently used to validate the ColdUAS.

Risk factors for systemic reactions in typical cold urticaria: Results from the COLD-CE study.

BACKGROUND: Cold urticaria (ColdU), that is, the occurrence of wheals or angioedema in response to cold exposure, is classified into typical and atypical forms. The diagnosis of typical ColdU relies on whealing in response to local cold stimulation testing (CST). It can also manifest with cold-induced anaphylaxis (ColdA). We aimed to determine risk factors for ColdA in typical ColdU. METHODS: An international, cross-sectional study COLD-CE was carried out at 32 urticaria centers of reference and excellence (UCAREs). Detailed history was taken and CST with an ice cube and/or TempTest® performed. ColdA was defined as an acute cold-induced involvement of the skin and/or visible mucosal tissue and at least one of: cardiovascular manifestations, difficulty breathing, or gastrointestinal symptoms. RESULTS: Of 551 ColdU patients, 75% (n = 412) had a positive CST and ColdA occurred in 37% (n = 151) of the latter. Cold-induced generalized wheals, angioedema, acral swelling, oropharyngeal/laryngeal symptoms, and itch of earlobes were identified as signs/symptoms of severe disease. ColdA was most commonly provoked by complete cold water immersion and ColdA caused by cold air was more common in countries with a warmer climate. Ten percent (n = 40) of typical ColdU patients had a concomitant chronic spontaneous urticaria (CSU). They had a lower frequency of ColdA than those without CSU (4% vs. 39%, p = .003). We identified the following risk factors for cardiovascular manifestations: previous systemic reaction to a Hymenoptera sting, angioedema, oropharyngeal/laryngeal symptoms, and itchy earlobes. CONCLUSION: ColdA is common in typical ColdU. High-risk patients require education about their condition and how to use an adrenaline autoinjector.

Adrenaline autoinjector is under-prescribed in typical cold urticaria patients living in tropical climate countries.

Background: The diagnosis of typical cold urticaria (ColdU) relies on whealing in response to local cold stimulation testing (CST). It can also manifest with cold-induced anaphylaxis (ColdA). Till date, it is largely unclear how often patients with ColdU receive adrenaline treatment and are provided with an adrenaline autoinjector (AAI). Methods: An international, cross-sectional study, COLD-CE (i.e., comprehensive evaluation of ColdU and other cold-induced reactions), was carried out at 32 UCAREs. Detailed histories were taken and CST with an ice cube and/or TempTest® performed. ColdA was defined as an acute cold-induced (i.e., by cold water, air, or surfaces) involvement of the skin and/or visible mucosal tissue and at least one of the symptoms (cardiovascular manifestations, difficulty breathing, or gastrointestinal symptoms). Results: Of the 551 ColdU patients, 75% (n = 412) had a positive CST. Of them, concomitant chronic spontaneous urticaria was diagnosed in 10%. Of 372 patients with stand-alone ColdU, 69% were women and 91% adults. Their median age was 36 (IQR 26 - 48) years. Patients were also categorized into residents of countries with a tropical (n = 33), temperate (n = 264), or cold (n = 75) climate (Table 1: R13C1, R17C1, R21C1). AAI was more often prescribed to residents of temperate than tropical countries (30% vs. 12%, p = .038; Table 1: R31C1), although the frequency of ColdA did not significantly differ between these countries (44% vs. 42%, p = 1.000; R29C2). Residents of tropical countries had a higher frequency of ColdA induced by cold air than residents of temperate (36% vs. 12%, p = .001; R29C4) or cold (36% vs. 12%, p = .007; R25C4) countries. Cardiovascular manifestations induced by cold air were diagnosed in 33% (n = 11) of residents of tropical countries, but only 18% (n = 2) and 36% (n = 4) of them had received adrenaline and AAI, respectively (R13 - 15C7). Furthermore, hypotension and/or loss of consciousness induced by cold air occurred in 18% (n = 6) of patients, but only 17% (n = 1) received adrenaline (R13 - 14C10). ColdA was induced by complete cold water immersion in 9% (n = 3) of patients, and none of them received adrenaline treatment nor AAI (R13 - 15C3). Conclusion: Our findings suggest that ColdA is undertreated and call for changes in ColdU management.

Cold urticaria - What we know and what we do not know.

Cold urticaria (ColdU) is a common form of chronic inducible urticaria characterized by the development of wheals, angioedema or both in response to cold exposure. Recent research and guideline updates have advanced our understanding and management of ColdU. Today, its pathophysiology is thought to involve the cold-induced formation of autoallergens and IgE to these autoallergens, which provoke a release of proinflammatory mediators from skin mast cells. The classification of ColdU includes typical and atypical subtypes. We know that cold-induced wheals usually develop on rewarming and resolve within an hour and that anaphylaxis can occur. The diagnosis relies on the patient's history and cold stimulation testing. Additional diagnostic work-up, including a search for underlying infections, should only be done if indicated by the patient's history. The management of ColdU includes cold avoidance, the regular use of nonsedating antihistamines and the off-label use of omalizumab. However, many questions regarding ColdU remain unanswered. Here, we review what is known about ColdU, and we present important unanswered questions on the epidemiology, underlying pathomechanisms, clinical heterogeneity and treatment outcomes. Our aim is to guide future efforts that will close these knowledge gaps and advance the management of ColdU.

Stepping Down Treatment in Chronic Spontaneous Urticaria: What We Know and What We Don't Know.

In chronic spontaneous urticaria (CSU), wheals, angioedema, or both appear spontaneously for > 6 weeks. Current recommended treatment options for urticaria target mast cell mediators such as histamine, or activators, such as autoantibodies. The goal of CSU treatment is to treat the disease until it is gone as effectively and safely as possible. As no cure is available for CSU as of now, the treatment is aimed at continuously suppressing disease activity, with complete control of the disease and a normalization of quality of life. To achieve this, pharmacological treatment should be continued until no longer needed. Treatment of CSU should follow the basic principles of treating as much as needed and as little as possible taking into consideration that the activity of the disease may vary. Since CSU is a disease with spontaneous remission, it is hard to tell, in patients with complete control and no signs or symptoms, when medication is no longer needed. The current international guideline for urticaria suggests that the treatment can be stepped down once a patient is free of signs and symptoms. Other reasons for stepping down the treatment of CSU patients include safety concerns or issues, pregnancy or wanting to become pregnant, and economic factors. As of now, it is unclear over which period, with what intervals and with which dosages CSU treatment should be stepped down. Guidance on this is needed for all recommended therapies: (i) standard-dosed second-generation H1-antihistamine (sgAH), (ii) higher than standard-dosed sgAH, (iii) standard-dosed omalizumab, (iv) higher than standard-dosed omalizumab, and (v) cyclosporine. However, there is a lack of controlled trials on the step down and discontinuation of these treatments. Here, we aim to provide a summary of what is known and what needs to be investigated in further studies, based on our own experience and real-world evidence.

Positive Basophil Tests Are Linked to High Disease Activity and Other Features of Autoimmune Chronic Spontaneous Urticaria: A Systematic Review.

BACKGROUND: Chronic spontaneous urticaria (CSU) is believed to be Autoimmune (aiCSU) (type IIb CSU) in at least 8% of patients, associated with mast cell-activating IgG autoantibodies. Basophil tests such as the basophil activation test (BAT) and basophil histamine release assay (BHRA) are considered the best single tests for an aiCSU diagnosis. To date, the strength of associations among a positive BAT and/or BHRA (BAT/BHRA+) and CSU features, patient demographics, and response to treatment remains poorly characterized. OBJECTIVE: To evaluate the strength of current evidence on basophil tests as parameters for CSU characteristics. METHODS: We performed a systematic literature search and review to assess the relationship between BAT/BHRA+ and clinical and laboratory parameters of CSU. Of 1,058 records found in the search, 94 studies were reviewed by experts in urticaria and 42 were included in the analysis. RESULTS: In CSU patients, BAT/BHRA+ showed a strong level of evidence for an association with high disease activity and low levels of total IgE. A weak level of evidence was shown for the association of BAT/BHRA+ and the presence of angioedema, and basopenia. CONCLUSIONS: Our results suggest that aiCSU defined by BAT/BHRA+ is more active or severe and is linked to other aiCSU markers such as low total IgE/basopenia. Basophil tests should be standardized and implemented in routine clinical care to improve the diagnosis and treatment of patients with aiCSU.

In the skin lesions of patients with mycosis fungoides, the number of MRGPRX2-expressing cells is increased and correlates with mast cell numbers.

Background: Mycosis fungoides (MF) is an indolent T-cell lymphoma that mainly affects the skin and presents with itch in more than half of the patients. Recently, the expression of Mas-related G protein-coupled receptor X2 (MRGPRX2), a receptor of mast cell (MC) responsible for the IgE-independent non-histaminergic itch, has been shown in lesional skin of patients with pruritic skin diseases, including chronic urticaria, prurigo, and mastocytosis. As of yet, limited knowledge exists regarding the MRGPRX2 expression in the skin of patients with MF. Objectives: To investigate the number of MRGPRX2-expressing (MRGPRX2+) cells in the skin of patients with MF and its correlation with clinical and laboratory characteristics of the disease. Methods: MRGPRX2 was analyzed in lesional and non-lesional skin of MF patients and healthy skin tissues by immunohistochemistry. Co-localization of MRGPRX2 with the MC marker tryptase was assessed by immunofluorescence. Public single-cell RNAseq data was reanalyzed to identify the MRGPRX2 expression on the distinct cell types. Results: In lesional skin of MF patients, MRGPRX2+ cell number was higher than in non-lesional skin and healthy control skin (mean:15.12 vs. 6.84 vs. 5.51 cells/mm2, p=0.04), and correlated with MC numbers (r=0.73, p=0.02). MC was the primary cell type expressing MRGPRX2 in MF patients. The ratio of MRGPRX2+ MCs to MRGPRX2+ cells in lesional and non-lesional skin correlated with the severity of disease (r=0.71, p=0.02 and r=0.67, p=0.03, respectively). Conclusions: Our findings point to the role of MRGPRX2 and MC in the pathogenesis of MF that should be investigated in further studies.

Disease Impact, Diagnostic Delay, and Unmet Medical Needs of Patients With Cholinergic Urticaria in German-Speaking Countries.

Background: Cholinergic urticaria (CholU) is a common type of chronic inducible urticaria. Little is known about the burden of the disease and its unmet medical needs. Aim: To characterize the unmet medical needs of patients with CholU. Methods: Patients with CholU (n = 111) took part in a German online survey that assessed their symptoms, diagnostic delay, impact on daily life, quality of life (QoL), and their experience with physician care. Results: Virtually all patients reported typical signs and symptoms of CholU, i.e., whealing (93.7%) and itching (91.9%), in response to typical trigger situations, such as physical activity, passive warming, or stress. Despite this, patients reported a marked diagnostic delay of 30.2 months (range from 0 to 279 months). Only 38% of the patients received a blood examination, and only 16% underwent provocation testing for diagnosing CholU, as recommended by the international guidelines. Physician contacts were common, but patient satisfaction with their disease management was low. In total, 90.1% of the patients stated to have an uncontrolled disease, resulting in a strong impact on their everyday activities, sleep, and QoL. Conclusion: Patients with CholU exhibit many important unmet needs, and improvement in the diagnostic workup and patient care is needed, as are better treatment options.

Impaired sweating in patients with cholinergic urticaria is linked to low expression of acetylcholine receptor CHRM3 and acetylcholine esterase in sweat glands.

Background: Cholinergic urticaria (CholU), a frequent form of chronic inducible urticaria, is characterized by itchy wheals and angioedema in response to sweating. As of now, the rate and pathophysiological relevance of impaired sweating in patients with CholU are ill-defined. Aim: To assess in CholU patients the rate and extent of impaired sweating and its links to clinical and pathophysiological features of CholU. Patients and methods: We assessed sweating in patients with CholU (n = 13) subjected to pulse-controlled ergometry (PCE) provocation testing. Pre- and post-PCE biopsies of lesional (L) and non-lesional (NL) skin were analyzed for the expression of acetylcholine receptor M3 (CHRM3) and acetylcholine esterase (ACh-E) by quantitative histomorphometry and compared to those of healthy control subjects (HCs). CholU patients were assessed for disease duration and severity as well as other clinical features. Results: Of the 13 patients with CholU, 10 showed reduced sweating in response to PCE provocation, and 3 had severely reduced sweating. Reduced sweating was linked to long disease duration and high disease severity. CholU patients with impaired sweating responses showed reduced sweat gland epithelial expression of CHRM3 and ACh-E. Conclusion: Reduced sweating is common in CholU patients, especially in those with long-standing and severe disease, and it can be severe. Reduced expression of CHRM3 and ACh-E may be the cause or consequence of CholU in patients with impaired sweating, and this should be explored by further studies.

Mast cells and tryptase are linked to itch and disease severity in mycosis fungoides: Results of a pilot study.

Introduction: In mycosis fungoides (MF), the most common cutaneous T-cell lymphoma, itch is a frequent clinical symptom. Whether mast cells (MCs), eosinophils (Eos) or their mediators play a role in MF-associated itch or disease severity is controversially discussed. Here, we explored the role of MC and Eo numbers in the skin as well as blood levels of their mediators in disease severity and itch. Methods: In 10 patients with MF and 10 matched control subjects we assessed disease severity, itch, and quality of life impairment using dedicated tools such as the mSWAT, ItchyQoL and DLQI. We analyzed skin biopsies and measured serum levels of tryptase, a mast cell mediator, as well as of the eosinophil products eosinophil cationic protein (ECP) and major basic protein (MBP). Results: The presence of chronic itch, in four of 10 patients, was associated with significantly higher disease severity (mSwat), larger body surface area affected, and stronger QoL impairment (Itchy-Qol, DLQI). Serum levels of tryptase, but not ECP and MBP, were linked with patient-reported disease severity, body surface area affected, and the presence of itch. Three of the four patients with chronic itch, but none of the six patients without, had tryptase levels above >6µg/l. Numbers of MCs in the papillary dermis were higher in MF skin lesions then in non-lesional skin of MF patients and skin of healthy controls. Discussion: The MC-mediator tryptase, in MF, is linked to disease activity and impact, most prominently to itch. Our findings call for larger studies that explore the role of MCs, tryptase and other MC mediators as drivers of itch and their role in MF pathogenesis.