Relationship between changes in the 7-day urticaria activity score after treatment with omalizumab and the responsiveness of basophils to FcεRI stimulation in patients with chronic spontaneous urticaria

BTK signaling-a crucial link in the pathophysiology of chronic spontaneous urticaria

Chronic spontaneous urticaria (CSU) is an inflammatory skin disorder that manifests with itchy wheals, angioedema, or both for more than 6 weeks. Mast cells and basophils are the key pathogenic drivers of CSU; their activation results in histamine and cytokine release with subsequent dermal inflammation. Two overlapping mechanisms of mast cell and basophil activation have been proposed in CSU: type I autoimmunity, also called autoallergy, which is mediated via IgE against various autoallergens, and type IIb autoimmunity, which is mediated predominantly via IgG directed against the IgE receptor FcεRI or FcεRI-bound IgE. Both mechanisms involve cross-linking of FcεRI and activation of downstream signaling pathways, and they may co-occur in the same patient. In addition, B-cell receptor signaling has been postulated to play a key role in CSU by generating autoreactive B cells and autoantibody production. A cornerstone of FcεRI and B-cell receptor signaling is Bruton tyrosine kinase (BTK), making BTK inhibition a clear therapeutic target in CSU. The potential application of early-generation BTK inhibitors, including ibrutinib, in allergic and autoimmune diseases is limited owing to their unfavorable benefit-risk profile. However, novel BTK inhibitors with improved selectivity and safety profiles have been developed and are under clinical investigation in autoimmune diseases, including CSU. In phase 2 trials, the BTK inhibitors remibrutinib and fenebrutinib have demonstrated rapid and sustained improvements in CSU disease activity. With phase 3 studies of remibrutinib ongoing, it is hoped that BTK inhibitors will present an effective, well-tolerated option for patients with antihistamine-refractory CSU, a phenotype that presents a considerable clinical challenge.

Precision Dermatology: A Review of Molecular Biomarkers and Personalized Therapies

The evolution of personalized medicine in dermatology signifies a transformative shift towards individualized treatments, driven by the integration of biomarkers. These molecular indicators serve beyond diagnostics, offering insights into disease staging, prognosis, and therapeutic monitoring. Specific criteria guide biomarker selection, ensuring attributes like specificity, sensitivity, cost feasibility, stability, rapid detection, and reproducibility. This literature review, based on data from PubMed, SCOPUS, and Web of Science, explores biomarkers in Hidradenitis Suppurativa (HS), Psoriasis, Atopic Dermatitis (AD), Alopecia Areata (AA), Vitiligo, and Chronic Spontaneous Urticaria (CSU). In HS, TNF-α, IL-1β, and MMPs serve as biomarkers, influencing targeted therapies like adalimumab and anakinra. Psoriasis involves biomarkers such as TNF-α, IL-23, and HLA genes, shaping treatments like IL23 and IL17 inhibitors. AD biomarkers include ECP, IL-4, IL-13, guiding therapies like dupilumab and tralokinumab. For AA, lipocalin-2, cytokines, and genetic polymorphisms inform JAK inhibitors' use. Vitiligo biomarkers range from cytokines to genetic markers like TYR, TYRP1, guiding treatments like JAK inhibitors. CSU biomarkers encompass IgE, cytokines, and autologous serum tests, influencing therapies like omalizumab and cyclosporine. Comparing conditions, common proinflammatory markers reveal limited specificity. While some biomarkers aid diagnosis and standard treatments, others hold more scientific than clinical value. Precision medicine, driven by biomarkers, has shown success in skin malignancies. Future directions involve AI-powered algorithms, nanotechnology, and multi-omics integration for personalized dermatological care.

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.

Thyroid Autoimmunity in CSU: A Potential Marker of Omalizumab Response?

The response of severe chronic spontaneous urticaria (CSU) to omalizumab largely depends on the autoimmune or autoallergic endotype of the disease. Whether thyroid autoimmunity may predict omalizumab response along with total IgE in CSU is still unclear. Three hundred and eighty-five patients (M/F 123/262; mean age 49.5 years; range 12-87 years) with severe CSU were studied. Total IgE levels and thyroid autoimmunity (levels of anti-thyroid peroxidase [TPO] IgG) were measured before omalizumab treatment. Based on the clinical response, patients were divided into early (ER), late (LR), partial (PR) and non (NR) responders to omalizumab. Thyroid autoimmunity was detected in 92/385 (24%) patients. Altogether, 52%, 22%, 16% and 10% of patients were ER, LR, PR and NR to omalizumab, respectively. Response to omalizumab was not associated with thyroid autoimmunity (p = 0.77). Conversely, we found a strongly positive association between IgE levels and omalizumab response (p < 0.0001); this association was largely driven by early response (OR = 5.46; 95% CI: 2.23-13.3). Moreover, the predicted probabilities of early response strongly increased with increasing IgE levels. Thyroid autoimmunity alone cannot be used as a clinical predictor of omalizumab response. Total IgE levels remain the only and most reliable prognostic marker for omalizumab response in patients with severe CSU.

Urticaria and Angioedema: Understanding Complex Pathomechanisms to Facilitate Patient Communication, Disease Management, and Future Treatment

Chronic spontaneous urticaria (CSU) is primarily a T2-dominant disease with a complex genetic background. Skin mast cell activation can be induced not only via the IgE-FcεRI axis but also from several other distinct mechanisms, molecules, and receptors involved in CSU onset, persistence, and exacerbation. These include autoallergy, autoimmunity, central or peripheral neuroimmune dysregulation, activation of both extrinsic and intrinsic coagulation pathways, and microbial infections. Besides mast cells, recent reports suggest the active and direct involvement of basophils and eosinophils. Several biological characteristics or biomarkers have been linked with CSU's known endotypes and may help forecast therapeutic responses. The introduction of biologic therapy for CSU has been a major advance in the last 10 years. The cornerstone of angioedema (AE) pathogenesis is increased vascular permeability and plasma leakage into the deeper dermis and subcutis, either mediated by histamine or bradykinin (BK). C1-inhibitor deficiency, hereditary or acquired, is the primary cause of BK-mediated AE due to increased plasma BK concentration. Other complex conditions have been identified, with some likely involving contact system dysregulation and other putative mechanisms related to vascular endothelial dysfunction. The approval of multiple hereditary-AE-specific therapies for both prevention and acute attacks has revolutionized treatment of this disease. Any new knowledge of the pathogenesis of CSU and AE offers the opportunity to improve patient information, physician-patient communication, prediction of therapeutic responses, selection of precise tailor-made treatment for each patient, and exploration of novel treatment options for those who do not achieve disease control with current medications.

Biologics for chronic spontaneous urticaria: toward a personalized treatment

INTRODUCTION

Chronic spontaneous urticaria (CSU) is characterized by the recurrent occurrence of short-lived wheals with or without angioedema for more than 6 weeks. Although its pathogenesis is not completely defined, several mechanisms seem involved, including autoimmunity and autoallergy with complement and coagulation activation. Various biologics are currently available or under investigation to counteract different CSU pathomechanisms.

AREAS COVERED

The recent literature dealing with biologics in the treatment of CSU was screened and analyzed; the different treatments were divided into anti-IgE and other than anti-IgE biologics. The latter were subdivided according to their target mechanisms.

EXPERT OPINION

Biologic drugs exert their effects in a very precise and specific manner. A majority of patients (arguably those with type I disease) respond to anti-IgE treatment. Others, possibly with type IIa disease, show a slow response to anti-IgE drugs. Things are much more complicated in anti-IgE-refractory patients. Some respond well to nonspecific immune suppressors, such as corticosteroids and cyclosporin suggesting that an immune-mediated pathogenic mechanism, not involving the high-affinity IgE receptor, is probably active. Several ongoing studies are evaluating biologics and small molecules counteracting other pathomechanisms, including anti-receptor biologics, Bruton tyrosine kinase (BTK) inhibitors, mast cell targets, and specific cytokines.

Autoimmune chronic spontaneous urticaria

Chronic spontaneous urticaria (CSU) is a debilitating mast cell-driven disease characterized by recurrent wheals and/or angioedema. Substantial progress has been made in dissecting the 2 main autoimmune mechanisms that drive the pathogenesis of CSU. Type I autoimmune (autoallergic) CSU is associated with IgE antibodies against autoantigens, for example, thyroid peroxidase and IL-24. Type IIb autoimmune CSU is mediated by autoantibodies that activate mast cells, for example, via IgE and FcεRI, and is present in less than 10% of patients with CSU when strict criteria are used, that is, triple positivity of autologous serum skin test, immunoassays for IgG autoantibodies, and basophil activation tests. A subpopulation of patients with CSU has both types. Type IIb autoimmune CSU is characterized by higher disease severity, concomitant autoimmune diseases, low levels of total IgE, elevated levels of IgG-anti-thyroid peroxidase, basopenia, eosinopenia, poor response to antihistamines and to omalizumab, and a good response to cyclosporine. Novel targeted therapies for CSU are under development such as ligelizumab, an anti-IgE, fenebrutinib and remibrutinib, Bruton's tyrosine kinase inhibitors, and dupilumab, an anti-IL-4Rα. Further studies should investigate the overlap between autoallergic and type IIb autoimmune CSU, optimize the diagnosis of both autoimmune endotypes using easy-to-perform, noninvasive, and inexpensive markers, and assess differences in response to therapy.

What Basophil Testing Tells Us About CSU Patients - Results of the CORSA Study

Basophil testing is the most effective single approach for diagnosing type-IIb autoimmune chronic spontaneous urticaria (TIIbaiCSU). A positive basophil test has been linked to long disease duration, higher disease activity, a poor response to antihistamines and omalizumab, and a better response to cyclosporine and fenebrutinib. As of now it is unclear what other features are connected to a positive basophil test in chronic spontaneous urticaria (CSU). We aimed to identify features of basophil test-positive CSU patients. We performed a cross-sectional study of 85 CSU patients. Basophil testing was done with the basophil activation test (BAT) and the basophil histamine release assay (BHRA). Data were analysed using SPSS: Student's t-test, Chi-square test, Odds Ratio, Spearman's correlation test. Of 85 CSU patients, 44% and 28% tested positive with the BAT and BHRA, respectively. These patients showed higher disease activity and impact, lower levels of disease control and total serum IgE, as well as higher rates of having a positive autologous serum skin test (ASST), angioedema, nocturnal symptoms, symptoms for >5 days/week, and thyroid autoantibodies. The ASST, by itself, was not a good predictor of basophil test results, but it predicted a positive basophil test in up to 100% of cases when combined with angioedema, thyroid autoantibodies or low IgE. In conclusion, a positive basophil test is linked to known features of TIIbaiCSU and novel characteristics including nocturnal symptoms. Further studies on basophil test-positive and -negative CSU patients can help to better understand CSU endotypes and to develop better management approaches.

Biomarkers of chronic spontaneous urticaria and their clinical implications

Introduction: Chronic spontaneous urticaria (CSU) is a frequent disorder in which activation of effector cells and histamine release can be induced via several distinct pathogenetic mechanisms. Much work has been carried out to identify biomarkers useful for classifying CSU patients, and to predict their response to currently available treatments.Areas covered: The recent literature dealing with CSU biomarkers was screened in PubMed and Google Scholar using 'chronic spontaneous urticaria', 'biomarker', 'diagnosis', 'therapy' and 'treatment response' as key words. The characteristics found in relevant papers were divided into clinical and serological biomarkers of (a) clinical severity/disease activity, and (b) response to treatments.Expert opinion: A diagnostic biomarker for CSU is still missing. Most biomarkers described so far do not seem to possess sufficient specificity for this disease. Basopenia and the activation of the coagulation cascade might be biomarkers of disease activity and severity, but information available so far is insufficient to consider their routine use. Markers suggesting IgG-mediated autoimmunity (autologous serum skin test, basophil activation/histamine release assays, low total IgE) seem to identify patients less prone to respond to omalizumab but responsive to cyclosporine. In contrast, 'autoallergy' (i.e. the presence of IgE to autoallergens), which is often associated with elevated IgE levels seems to identify patients who will respond to omalizumab.