Autoreactive T cells in chronic spontaneous urticaria target the IgE Fc receptor Iα subunit

CD4+CCR5+ T cells and CCL3+ mast cells are increased in the skin of patients with chronic spontaneous urticaria

Background

The proximity of activated T cells and mast cells in the lesional skin of patients with chronic spontaneous urticaria (CSU) is held to contribute to the development of wheals and angioedema. In a previous study, we demonstrated that increased IL-17 expression in T cells and mast cells in skin lesions of patients with CSU is associated with T/mast cell proximity, but the mechanisms that drive T cell/mast cell co-localization remain unknown.

Objectives

To assess if chemokines expressed in lesional CSU skin contribute to T cell/mast cell proximity.

Patients and methods

Biopsies from lesional CSU skin were compared to biopsies from healthy skin for expression of CCR5 and its ligand CCL3 by CD4+ T cells and mast cells, respectively.

Results

Numbers of CCR5-positive CD4+ T cells in lesional CSU skin were significantly increased as compared to healthy normal skin (p < 0.0001). The number of mast cells expressing CCL3 (ligand for CCR5) in CSU skin was also increased (p < 0.0002) and significant association with T-cell close proximity (p < 0.0001) is noticed.

Conclusions

The close proximity of T cells and mast cells in the skin of severe CSU may be driven, at least in part by increased CCR5 and CCL3 expression. Therapies that target CCL3 interaction with CCR5 should be assessed for their effects in CSU.

Consecutive injections of low-dose interleukin-2 improve symptoms and disease control in patients with chronic spontaneous urticaria

PURPOSE

To describe the effectiveness and tolerability of low-dose interleukin (IL)-2 in treating patients with chronic spontaneous urticaria (CSU) refractory to H₁-antihistamines.

METHODS

This retrospective study included CSU patients who received treatment with at least one cycle of IL-2, injected intramuscularly at a dose of 1.0 million international units daily for 7 consecutive days, after failing treatment with H₁-antihistamines. Patients were followed up for ≥12 weeks.

RESULTS

Of the 15 patients, 7 (46.7%) and 11 (73.3%) achieved complete response at Week 2 and Week 12, respectively. The mean change of urticaria control test (UCT) and weekly urticaria activity score (UAS7) from baseline was 6.6 (95% CI, 4.2 to 8.9) and - 16.9 (95% CI, -24.0 to -9.8), respectively, at Week 12. Local injection-site reactions were the most common adverse events. No serious adverse events were reported.

CONCLUSION

Low-dose IL-2 treatment improves symptoms and disease control for CSU patients refractory to H₁-antihistamines.

Self-reactive IgE and anti-IgE therapy in autoimmune diseases

Growing evidence indicates the pathogenic role of autoreactive IgE in autoimmune diseases. Incidence of autoimmune and allergic diseases in the industrialized countries is consistently icreasing, thus leading to concerted efforts to comprehend the regulation of IgE-mediated mechanisms. The first reports of a presence of IgE autoantibodies in patients with autoimmune diseases have been published a long time ago, and it is now recognized that self-reactive IgE can mediate inflammatory response in bullous pemhigoid, systemic lupus erythematosus, chronic urticaria, and atopic dermatitis. The advances in understanding the pathomechanisms of these disorders brought to a successful use of anti-IgE strategies in their management. The present review discusses the current state of knowledge on the IgE-mediated autoimmunity and anti-IgE treatment, and pave the way for further exploration of the subject.

DNA methylation regulatory patterns and underlying pathways behind the co-pathogenesis of allergic rhinitis and chronic spontaneous urticaria

Background

Allergic rhinitis (AR) and chronic spontaneous urticaria (CSU) are often concurrent in patients. Changes in DNA methylation affect T cell biological processes, which may explain the occurrence and progression of comorbidity. However, downstream regulatory pathways of DNA methylation in two diseases and the underlying mechanisms have not been fully elucidated.

Methods

The GSE50101, GSE72541, GSE50222 and OEP002482 were mined for the identification of differentially expressed genes (DEGs) or co-expressed genes and differentially methylated genes (DMGs) in AR and CSU patients. We applied GO analysis and consensus clustering to study the potential functions and signal pathways of selected genes in two diseases. GSVA and logistic regression analysis were used to find the regulatory pathway between DNA methylation and activation patterns of CD4+ T cells. Besides, we used the Illumina 850k chip to detect DNA methylation expression profiles and recognize the differentially methylated CpG positions (DMPs) on corresponding genes. Finally, we annotated the biological process of these genes using GO and KEGG pathway analysis.

Result

The AR-related DEGs were found closely related to the differentiation and activation of CD4+ T cells. The DEGs or co-expressed genes of CD4+ T cells in AR and CSU patients were also clustered using GO and KEGG analysis and we got 57 co-regulatory pathways. Furthermore, logistic regression analysis showed that the regulation of cellular component size was closely related to the activation of CD4+ T cells regulated by DNA methylation. We got self-tested data using the Illumina 850k chip and identified 98 CpGs that were differentially methylated in patients. Finally, we mapped the DMPs to 15 genes and found that they were mainly enriched in the same CD4+T cell regulating pathway.

Conclusion

Our study indicated that DNA methylation affected by pollen participated in the activation patterns of CD4 + T cells, providing a novel direction for the symptomatic treatment of the co-occurrence of AR and CSU.

Gut Microbiome Composition in Patients with Chronic Urticaria: A Review of Current Evidence and Data

Recent studies have linked gut microorganism composition and chronic urticaria (CU); however, the underlying mechanisms responsible for this connection are unknown. Since the human immune system is in homeostasis with microbiota, and the composition of the microbiome regulates the development and function of the immune system, it is likely that an alteration of microbiota components (a dysbiosis) could influence the course of chronic spontaneous urticaria (CSU), including disease severity, patient quality of life and treatment outcome. To date, several studies have identified changes in the gut microbiota composition of patients with CSU, though only a few have exhibited metabolic abnormalities associated with gut dysbiosis. The studies on CSU patients predominantly showed that the relative abundance of beneficial bacteria was decreased (Firmicutes and Bacteroides), while that of opportunistic bacteria was increased (Enterobacteria and Proteobacteria). In addition, serum metabolome analysis revealed that gut microbiota-associated alterations in unsaturated fatty acids and the butanoate metabolism pathway may play a role in CSU. These findings are potentially associated with inflammation mediated by the imbalance of Th1/Th2/Th17 cytokines, which might contribute to CSU pathogenesis. Further research in this field could improve clinical, diagnostic, and therapeutic approaches to patients with CSU. By applying new knowledge on gut microbial communities and metabolomics, future CSU therapies could modify the microbiota composition using agents such as probiotics or other similar agents, which, in combination with current standard therapies, could hopefully lead to a reduction in symptoms and an improved quality of life for CSU patients.

Potential contribution of Helicobacter pylori proteins in the pathogenesis of type 1 gastric neuroendocrine tumor and urticaria. In silico approach

BACKGROUND

Helicobacter pylori has been linked to several diseases such as chronic urticaria, gastritis, and type 1 gastric neuroendocrine tumors (type 1 gNET). Although these diseases seem to have different mechanisms, their relationship with H. pylori suggests a common inflammatory pathway.

OBJECTIVE

To identify potential cross-reactive antigens between H. pylori and humans involved in chronic urticaria and type 1 gNET.

METHODS

Alignment was carried out among human proteins associated with urticaria (9 proteins), type 1 gNET (32 proteins), and H. pylori proteome. We performed pairwise alignment among the human and H. pylori antigens with PSI-BLAST. Modeling based on homology was done with the Swiss model server and epitope prediction with the Ellipro server. Epitopes were located on a 3D model using PYMOL software.

RESULTS

The highest conserved sequence was found between the human HSP 60 antigen and the H. pylori chaperonin GroEL with an identity of 54% and a cover of 92%, followed by the alpha and gamma enolases and two H. pylori phosphopyruvate hydratase, both with an identity and cover of 48% and 96%, respectively. The H/K ATPase (Chain A) showed high identity with two H. pylori proteins (35.21% with both P-type ATPase), but with low cover (only 6%). We observed eight linear and three discontinuous epitopes for human HSP 60 and three lineal and one discontinuous epitope for both alpha-enolase and gamma enolase, high conserved with H. pylori sequences.

CONCLUSION

Some type 1 gNET antigens shared potential cross-reactive epitopes with H. pylori proteins, suggesting that molecular mimicry could be a mechanism that explains the relationship between the infection and this disease. Studies evaluating the functional impact of this relationship are needed.

In silico Identification of Immune Cell-Types and Pathways Involved in Chronic Spontaneous Urticaria

Background

The immunopathogenesis of chronic spontaneous urticaria (CSU) is poorly understood, but recent research suggests that patients can be divided into autoallergic and autoimmune subtypes. Given that not all patients can be controlled with current treatment regimens, including anti-IgE monoclonal antibodies, a better understanding of the immune pathways involved in CSU may enable the repurposing of monoclonal antibodies used for other dermatologic diseases (e.g., Th2 and Th17 inhibitors). Therefore, we investigated the implicated immune cells and pathways by reanalyzing publicly available transcriptomic data.

Methods

Microarray data of CSU and healthy control (HC) skin and blood were obtained from the Gene Expression Omnibus (GSE72542, GSE57178). Differentially expressed genes were defined as a false discovery rate <0.05 and a |log₂ fold change| ≥1. Pathway analyses were conducted using ToppGene and KEGG. Cell-type enrichment was determined by CIBERSORT and xCell and was correlated with clinical characteristics.

Results

Th2 (IL-4/13 signaling) and Th17-related (IL-17/23 signaling) pathways were upregulated in lesional compared to non-lesional and HC samples. In non-lesional versus lesional samples, CIBERSORT analysis revealed increased regulatory T-cells (Treg) and resting mast cells. xCell analysis established that Th1 and Th2 scores were not significantly different between lesional and HC samples. However, Th2 scores in both lesional and non-lesional samples correlated positively with disease severity. Few differentially expressed genes and pathways were identified between CSU and HC blood samples.

Conclusion

Our results support the involvement of Th2 and Th17-related genes and pathways in CSU. Th2 scores associate with disease severity, which indicates the clinical relevance of these findings. Increased resting mast cell and Treg scores in non-lesional samples may suggest local suppression of wheal formation. Moreover, disease activity seemed to be restricted to the skin as there were limited findings from blood. Larger studies using next-generation sequencing will be helpful to confirm these results.

IL-31: State of the Art for an Inflammation-Oriented Interleukin

Interleukin 31 belongs to the IL-6 superfamily, and it is an itch mediator already studied in several diseases, comprising atopic dermatitis, allergic pathologies, and onco-hematological conditions. This research aims to assess the role of this cytokine in the pathogenesis of these conditions and its potential therapeutic role. The research has been conducted on articles, excluding reviews and meta-analysis, both on animals and humans. The results showed that IL-31 plays a crucial role in the pathogenesis of systemic skin manifestations, prognosis, and itch severity. Traditional therapies target this interleukin indirectly, but monoclonal antibodies (Mab) directed against it have shown efficacy and safety profiles comparable with biological drugs that are already available. Future perspectives could include the development of new antibodies against IL-31 both for humans and animals, thus adding a new approach to the therapy, which often has proven to be prolonged and specific for each patient.

The Role of Crosstalk of Immune Cells in Pathogenesis of Chronic Spontaneous Urticaria

Chronic spontaneous urticaria (CSU) is defined as recurrent episodes of spontaneous wheal development and/or angioedema for more than six weeks and at least twice a week. The core link in the pathogenesis of CSU is the activation of mast cells, T cells, eosinophils, and other immune cells infiltrating around the small venules of the lesion. Increased vascular permeability, vasodilatation, and recruitment of inflammatory cells directly depend on mast cell mediators’ release. Complex regulatory systems tightly influence the critical roles of mast cells in the local microenvironment. The bias toward Th2 inflammation and autoantibodies derived from B cells, histamine expressed by basophils, and initiation of the extrinsic coagulation pathway by eosinophils or monocytes exerts powerful modulatory influences on mast cells. Cell-to-cell interactions between mast cells and eosinophils/T cells also are regulators of their function and may involve CSU’s pathomechanism. This review summarizes up-to-date knowledge regarding the crosstalk between mast cells and other immune cells, providing the impetus to develop new research concepts and treatment strategies for CSU.

Insights into urticaria in pediatric and adult populations and its management with fexofenadine hydrochloride

OBJECTIVE

The present narrative review provides a comprehensive update of the current knowledge on urticaria, both in adult and pediatric populations, and on the safety and efficacy of fexofenadine hydrochloride (HCl) as a treatment option.

DATA SOURCE

A literature search was conducted on Embase and Medline.

STUDY SELECTION

Clinical studies published in English and published between 1999 and 2020 were selected.

RESULTS

Although the exact pathogenesis of urticaria is not fully understood, multiple pathways of mast cell activation are discussed to explain the existence of phenotypically different clinical manifestations of urticaria. An overview of the worldwide prevalence of chronic urticaria, including disease burden and patient's quality of life is provided. The impact of urticaria on patient's life differs on the basis of whether its form is acute or chronic, but pharmacological approaches are most often needed to control the disabling symptoms. A summary of the current management of urticaria recommended by different guidelines across countries (Global; European; American; Australian; Asian; Japanese) is presented. Non-sedating, second-generation H₁-antihistamines are the preferred choice of treatment across several guidelines worldwide. Herein, the efficacy and safety of fexofenadine HCl, a representative second-generation H₁-antihistamine approved for the treatment of urticaria, is discussed. The occurrence of urticaria manifestations in COVID-19 patients is also briefly presented.

CONCLUSION

The burden of acute and chronic urticaria is high for patients. Second generation anti-histamines such as fexofenadine HCl can help managing the symptoms.

T-cell subsets in the skin and their role in inflammatory skin disorders

T lymphocytes (T cells) are major players of the adaptive immune response. Naive T cells are primed in the presence of cytokines, leading to polarization into distinct T-cell subsets with specific functions. These subsets are classified based on their T-cell receptor profile, expression of transcription factors, surface cytokine and chemokine receptors, and their cytokine production, which together determine their specific function. This review provides an overview of the various T-cell subsets and their function in several inflammatory skin disorders ranging from allergic inflammation to skin tumors. Moreover, we highlight similarities of T-cell responses across different skin disorders, demonstrating the presence of similar and opposing functions for the different T-cell subsets. Finally, we discuss the effects of currently available and promising therapeutic approaches to harness T cells in inflammatory skin diseases for which efficacy next to unwanted side effects provide new insights into the pathophysiology of skin disorders.

Immunological Targets of Biologic Drugs in Allergic Skin Diseases in Children

Atopic dermatitis and urticaria are two invalidating skin disorders that are very common in children. Recent advances in the understanding of their specific intracellular molecular pathways have permitted the development of precise biological molecules, targeting inflammatory mediators and arresting the pathogenetic pathways of skin diseases. Many biologics with promising results have been studied, although few are currently approved in children. In this review, we aim to provide the latest evidence about the use, indications, efficacy and safety of biologic therapies to treat atopic dermatitis and chronic urticaria in children and adolescents.

Chronic Urticaria: Advances in Understanding of the Disease and Clinical Management

Chronic urticaria (CU) is a common skin condition characterized by the recurrence of wheals, with or without angioedema, which lasts for at least 6 weeks. Owing to its pruritus and incurability, this disease adversely affects the patients' physical and mental health and diminishes the quality of life. CU is generally classified into two subtypes based on the relevance of eliciting factors: chronic spontaneous urticaria (CSU) and chronic inducible urticaria (CIndU), the latter of which is further divided into several subtypes. To improve the understanding and clinical management of this highly heterogeneous disorder, the EAACI/GA²LEN/EDF/WAO guideline was developed and published in 2018 based on evidence and expert consensus. The diagnostic and treatment algorithms proposed by the guideline have largely facilitated dermatologists in clinical practice. However, several questions remained unsolved and have been widely investigated in the recent years. First, a better understanding of the association between chronic urticaria and its potential underlying causes or eliciting factors such as autoimmunity, infections, coagulation aberrance, and vitamin D deficiency is warranted. This would lead to updates in the diagnostic and treatment procedures of different subtypes of chronic urticaria. Secondly, treatment for recalcitrant cases, especially those resistant to or intolerant of second-generation antihistamines and (or) omalizumab, calls for novel therapeutic measures or strategies. In the present review, we summarized recent advances in the understanding and management of both CSU and CIndU, with special emphasis on their underlying causes or eliciting factors, pathogenic mechanisms, potential targets for intervention, and advances in treatment strategies.

Predictive features associated with chronic spontaneous urticaria recurrence

When chronic spontaneous urticaria (CSU) is resolved, patients are often apprehensive about the likelihood of recurrence, and want to know if we can predict this using clinical or laboratory markers. This question is crucial because CSU is frequently accompanied by a high incidence of stressful comorbidities, and the fear of experiencing this again can be devastating to the patient. This study was designed with the aim of focusing on the prevalence and characteristics of the recurrence of CSU. We used our CSU patient registry that includes data on 180 patients who are followed periodically. In 23 (13%) patients, CSU was resolved during the first year. In 47 (26%) patients, CSU lasted more than 5 years. The recurrence of CSU was recorded in 21% of our patients after having experienced a full remission anywhere between 1 to 10 years (mean ± 2.9 years). While investigating predictive clinical or laboratory markers, we noticed that bronchial asthma existed in 10/25 (40%) of patients in whom CSU recurred as compared with 45/180 (25%) in the general CSU population (p = 0.049). In addition, increased levels of total immunoglobulin (Ig)E were found in 10/25 (40%) of the recurrence group as compared with 34/150 (23%) of the general CSU group (p = 0.04). Anti-thyroid peroxidase antibodies were also found in 11/25 (44%) of the recurrence group as compared with 32/160 (20%) of the general group (p = 0.003). The prevalence of CSU recurrence after a full remission is significantly higher among patients with existing bronchial asthma, increased levels of total IgE, and autoimmunity. Further studies are required in order to substantiate this important issue.

Autoreactive T cells and their role in atopic dermatitis

Atopic dermatitis (AD) is an itchy, non-contagious relapsing and chronic inflammatory skin disease that usually develops in early childhood. This pathology is associated with food allergy, allergic asthma, allergic rhinitis and anaphylaxis which may persist in adulthood. The underlying mechanisms of AD (endotypes) are just beginning to be discovered and show a complex interaction of various pathways including skin barrier function and immune deviation. Immune reactions to self-proteins (autoantigens) of the skin have been identified in patients with inflammatory skin diseases, such as chronic spontaneous urticaria, connective tissue disease, pemphigus vulgaris and bullous pemphigoid. IgE antibodies and T cells directed against epitopes of the skin were observed in adult patients with severe and chronic AD as well. This was associated with disease severity and suggests a progression from allergic inflammation to severe autoimmune processes against the skin. IgE-mediated autoimmunity and self-reactive T cells might accelerate the ongoing skin inflammation or might contribute to the relapsing course of the disease. However, to date, the exact mechanisms of IgE-mediated autoimmunity and self-reactive T cells in the pathophysiology of AD are still unclear. The aim of this review is to evaluate the development of (autoreactive) T cells and their response to (auto)antigens, as well as the role of the peripheral tolerance in autoimmunity in the pathophysiology of AD, including the unmet needs and gaps.

The Expression of IL-17, in Chronic Spontaneous Urticaria Is Linked to Semaphorin5A

Background: Patients with chronic spontaneous urticaria (CSU), an autoimmune disorder, show increased skin expression of IL-17A and can benefit from treatment with the anti-IL-17A biologic secukinumab. The mechanisms that drive IL-17A expression in CSU are currently unknown, but may involve Semaphorin5A (Sema5A). Objective: To explore the expression, role, and effects of Sema5A in CSU and its link to IL-17A. Material and Methods: We investigated patients with CSU and healthy controls for skin expression of expressing peripheral T cells. Results: Sema5A was highly expressed in the skin of CSU patients as compared to healthy control skin. Both CD4+ T cells and mast cells in CSU skin expressed Sema5A, and many of them expressed both Sema5A and IL-17A. Patients with CSU had significantly higher rates of IL-17A-expressing CD4+ T cells as compared to healthy controls. Incubation with Sema5A increased the rates of IL-17A-expressing CD4+ T cells in healthy controls to CSU levels. Conclusion: Sema5A may drive the expression and effects of IL-17A in CSU. Further studies in larger cohorts are needed to confirm the role of Sema5A in the pathogenesis of CSU and to explore its potential as a therapeutic target.

The Emerging Role of IL-17 in the Immune-Pathogenesis of Chronic Spontaneous Urticaria

Chronic spontaneous urticaria (CSU) is considered to be an autoimmune disorder (type I and type II) in 50% of all cases. However, autoreactive T cells and their proximity with activated mast cells in the skin of CSU patients are believed to be the primary event in mast cell degranulation. The finding of anti-FcɛRIα on mast cells or IgE autoantibodies against thyroid antigens should be considered to be a consequence of the auto-reactive T cells’ recognition of the above-mentioned antigens. Our recent finding of increased Th17 and IL-17 expression in both CD4+ T cells and mast cells in the skin of severe CSU patients is supportive for the major role that T cells perform in the pathogenesis of CSU. Supporting this are numerous previous reports in which increased serum IL-17 was found to be in association with CSU disease severity. The beneficial effect of anti-IL-17A (secukinumab) in CSU patients in whom high dose anti-histamines, recurrent course of steroids and omalizumab fail to achieve a reasonable response should be investigated as a new therapeutic strategy in future studies with a large cohort of patients.

Current and Potential Biologic Drugs for the Treatment of Chronic Urticaria

This article reviews biologic treatments that are currently applied for the treatment of severe chronic urticaria. Monoclonal anti-immunoglobulin E (omalizumab) is effective and safe in many patients, but accessibility and cost constitute barriers to its wider use. Questions on the optimal duration of the treatment and possible symptom recurrences after discontinuing the drug are still raised. A discussion is presented about several other biologics currently under investigation with potential to be incorporated in the near future in patients with severe chronic urticaria.

Mechanisms of skin autoimmunity: Cellular and soluble immune components of the skin

Autoimmune diseases are driven by either T cells or antibodies reacting specifically to 1 or more self-antigens. Although a number of self-antigens associated with skin diseases have been identified, the causative antigen(s) remains unknown in the great majority of skin diseases suspected to be autoimmune driven. Model diseases such as pemphigus, dermatitis herpetiformis, and more recently psoriasis have added greatly to our understanding of skin autoimmunity. Depending on the dominant T- or B-cell phenotype, skin autoimmune diseases usually follow 1 of 6 immune response patterns: lichenoid, eczematous, bullous, psoriatic, fibrogenic, or granulomatous. Usually, skin autoimmunity develops as a consequence of several events-an altered microbiome, inherited dysfunctional immunity, antigens activating innate immunity, epigenetic modifications, sex predisposition, and impact of antigens either as neoantigen or through molecular mimicry. This review summarizes currently known antigens of skin autoimmune diseases and discusses mechanisms of skin autoimmunity.

Chronic urticaria and thyroid pathology

Urticaria is defined as the sudden appearance of erythematous, itchy wheals of variable size, with or without angioedema (AE) (swelling of the deeper layers of the skin). Its classification depends on time course of symptoms and the presence of eliciting factors. When it lasts less than 6 weeks it is classified as acute urticaria (AU), and if the symptoms persist for more than 6 weeks, it is classified as chronic urticaria (CU). Current International Guidelines also classify CU as chronic spontaneous urticaria (CSU) and inducible urticarial, according to the absence or presence of environmental triggering factors. CSU is defined as urticaria and/or angioedema in which there is no evidence of a specific eliciting factor. CSU is associated with autoimmunity in 30-45% of the cases, sharing some immunological mechanisms with other autoimmune diseases, and is associated with autoimmune thyroid disease (ATD) in about 4.3%-57.4% patients. Several studies suggest that adequate therapy with anti-thyroid drugs or levothyroxine in early stages of ATD and CSU, may help to remit the latter; but there is still a lack of double-blind, placebo-controlled studies that support this hypothesis in patients without abnormal thyroid hormone levels. The objective of this review is to describe the pathophysiology of chronic spontaneous urticaria and its association with autoimmune thyroid disease.

Identification of antigenic epitopes of thyroperoxidase, thyroglobulin and interleukin-24. Exploration of cross-reactivity with environmental allergens and possible role in urticaria and hypothyroidism

BACKGROUND

Human proteins such as interleukin-24 (IL24), thyroperoxidase (TPO) and thyroglobulin (Tg) are targets of IgE or IgG autoantibodies. Why these proteins are recognized by autoantibodies in some patients with chronic spontaneous urticaria (CSU) or hypothyroidism is unknown.

OBJECTIVE

Through in silico analysis, identify antigen patches of TPO, Tg and IL24 and compare the sequences of these human proteins with some prevalent allergens.

METHODS

The amino acids sequences of IL24, thyroperoxidase and thyroglobulin were compared between them and with 22 environmental allergens. Phylogenetic studies and multiple pairing were carried out to explore the degree of protein identity and cover. The proteins without 3D structure reported in the database, were modeled by homology with "Swiss Modeller" and compared through PYMOL. Residues conserved and accessible to the solvent (rASA> 0.25) were located in the 3D model to identify possible areas of cross-reactivity and antigen binding.

RESULTS

We build a 3D model of the TPO and thyroglobulin protein base on proteins closely related. Five epitopes for TPO, six for IL24 and six for thyroglobulin were predicted. The amino acid sequences of allergens from different sources (Dermatophagoides pteronyssinus, Blomia tropicalis, Betula verrucosa, Cynodon dactylon, Aspergillus fumigatus, Canis domesticus, Felis domesticus) were compared with human TPO, Tg and IL24. The cover and alignments between allergens and human proteins were low.

CONCLUSION

We identify possible linear and conformational epitopes of TPO, Tg and IL24 that could be the target of IgE or IgG binding in patients with urticaria or hypothyroidism; These epitopes do not appear to be present among common environmental allergens, suggesting that autoreactivity to these human proteins are not by cross-reactivity.

Current and emerging treatments for chronic spontaneous urticaria

OBJECTIVE

To review the published literature on current and new treatments for chronic spontaneous urticaria (CSU) and to provide guidance on the potential use of these therapeutics.

DATA SOURCES

A PubMed search was performed to include English-language articles with the keywords chronic spontaneous urticaria, pathophysiology, quality of life, and treatments, with a preference to those articles written in the last 5 years. ClinicalTrials.gov was reviewed for recent relevant clinical trials related to potential CSU therapeutics.

STUDY SELECTIONS

Literature was included if it provided information related to the current understanding of the pathophysiology and management of CSU as well as potential novel therapeutics currently in development.

RESULTS

CSU has a significant effect on patients' quality of life. Current therapies include antihistamines, leukotriene receptor antagonists, omalizumab, and immunosuppressants; however, additional treatments are needed. New therapeutics under investigation include IgG1 anti-IgE monoclonal antibodies (ligelizumab), chemoattractant rector-homologous molecule expressed on T_H2 cells antagonists (AZD1981), Bruton tyrosine kinase inhibitors (fenebrutinib), anti-siglec-8 monoclonal antibody (AK002), and topical spleen tyrosine kinase inhibitors (GSK2646264). We review the mechanisms of action as well as recently published data from clinical trials regarding the efficacy and safety of these treatments.

CONCLUSION

The development of new treatments for CSU will lead to improved options for patients and may assist with improving our understanding of disease pathophysiology.

Autoimmune Theories of Chronic Spontaneous Urticaria

Urticaria (hives) is a highly prevalent skin disorder that can occur with or without associated angioedema. Chronic spontaneous urticaria (CSU) is a condition which persists for more than 6 weeks in duration and occurs in the absence of an identifiable provoking factor. CSU results from pathogenic activation of mast cells and basophils, which gives rise to the release of proinflammatory mediators that support the generation of urticaria. Several theories have been put forth regarding the pathogenesis of CSU with much evidence pointing toward a potential autoimmune etiology in up to 50% of patients with this condition. In this review, we highlight the evidence surrounding the autoimmune pathogenesis of chronic urticaria including recent data which suggests that CSU may involve contributions from both immunoglobin G (IgG)-specific and immunoglobulin E (IgE)-specific autoantibodies against a vast array of antigens that can span beyond those found on the surface of mast cells and basophils.

Association of positive and negative autologous serum skin test responses with clinical features of chronic spontaneous urticaria in Asian patients: A systematic review and meta-analysis

Previous studies on the correlation between positive autologous serum skin test (ASST) responses and the clinical features of patients with chronic spontaneous urticaria (CSU) have provided conflicting results. To evaluate the significance of ASST responses in CSU, a variety of databases were searched from inception to March 2018 to identify relevant studies on CSU. Data were analyzed with use of the Cochrane Collaboration's Review Manager 5.2. Multiple relevant factors of CSU were evaluated by calculating the weighted mean difference, odds ratio and 95% confidence interval. The results indicated that CSU cases with positive ASST responses had higher urticaria activity scores and higher levels of total serum immunoglobulin E than CSU cases with negative responses in the ASST. In addition, a positive ASST response was more likely to be accompanied with the presence of thyroid autoantibodies and angioedema. An increased prevalence of CSU was identified in females, who were more likely to have a positive response in the ASST. It was also indicated that a greater incidence of positive ASST responses was present in CSU patients as compared with that in healthy controls. No statistically significant differences were obtained between positive and negative ASST responses with regard to age and duration of disease. Based on these results, it was concluded that the ASST provides an effective means of predicting urticaria activity and recurrence in CSU patients.

The Efficacy and Safety of a Fixed Combination of Chinese Herbal Medicine in Chronic Urticaria: A Randomized, Double-Blind, Placebo-Controlled Pilot Study

Background: Chronic urticaria is a bothersome skin disease, and Chinese herbal medicine (CHM) is commonly used as adjuvant therapy. This study aimed to evaluate the effectiveness and safety of the mixture of two CHM formula, Xiao-Feng-San (XFS) and Qing-Shang-Fang-Feng-Tang (QSFFT), in treating urticaria through a randomized, double-blind, placebo-controlled clinical trial.

Methods: 78 participants entered the screening phase between November 2012 and August 2015. Participants were randomly and equally allocated in either CHM group (2 gm XFS and 2 gm QSFFT four times a day and 5 mg levocetirizine once daily for 28 days followed by 5 mg levocetirizine once daily alone for 28 days) or control group (placebo and 5 mg levocetirizine daily followed by 5 mg levocetirizine once daily for 28 days alone). Symptom improvement was set as the primary outcome, and the influence on sleep quality and changes in serum markers were used as secondary outcomes. Per protocol design was applied to the final analysis.

Results: A total of 56 participants entered the final analysis stage. Participants in the CHM group had more prominent symptom relief on day 56 (the weekly urticaria activity score, UAS7, as 9.9 ± 9.2 vs. 15.6 ± 10.8, p = 0.038). In the CHM group, participants' symptom severity reduced progressively (trend analysis, p < 0.001) while the decreasing trend was less favored in the control group (trend analysis, p = 0.056). The life quality improved gradually in both groups, while the differences between CHM and control groups were statistically insignificant. For urticaria-related cytokines, interferon-γ seemed to decrease positively in the CHM group (about 30.8% reduction from baseline, trend analysis p = 0.013). For safety issue, the CHM prescription was well-tolerated with no noticeable long-term side effects when compared to the control group. At 6-month follow-up of symptom changes after the end of the trial, the CHM group participants reported positive results in no recurrence or ≥50% improvement (36.3% in CHM group vs. 20% in Control group, p = 0.103).

Conclusions: The combination of XFS and QSFFT tended to be feasible and tolerable adjuvant therapy for urticaria in addition to standard therapy. However, larger study population with longer follow-up duration may be still needed.

Trial registration: NCT01715740 (ClinicalTrials.gov).

Chronic Spontaneous Urticaria: The Devil's Itch

Chronic urticaria is defined as the presence of urticaria for a period exceeding 6 weeks, assuming symptoms for most days of the week. It is divided into chronic inducible urticarias and chronic spontaneous urticaria, previously termed chronic idiopathic urticaria. The latter designation emphasizes that patients can experience urticaria independent of any exogenous stimulus even if one can define circumstances that may worsen symptoms. A search for such an external "cause" is fruitless because the underlying abnormality is "intrinsic," whether it is autoimmune, or some unknown process. Approximately 40% of patients with chronic spontaneous urticaria report accompanying episodes of angioedema, whereas 10% have angioedema as their primary manifestation. In most cases, it is a self-limiting disorder, persisting for 2 to 5 years in most cases, although 20% of patients suffer for more than 5 years. The treatment that has evolved is largely empiric, based on double-blind, placebo-controlled studies whenever possible, but is not yet targeted to any particular pathogenic mechanism. In this article, we review the current status regarding pathogenesis, discuss the diagnostic workup, and update the approach to treatment including consideration of published guidelines, our own experience, and guideline updates that are being prepared.

Approaches to target IgE antibodies in allergic diseases

IgE is the antibody isotype found at the lowest concentration in the circulation. However IgE can undeniably play an important role in mediating allergic reactions; best exemplified by the clinical benefits of anti-IgE monoclonal antibody (omalizumab) therapy for some allergic diseases. This review will describe our current understanding of the interactions between IgE and its main receptors FcεRI and CD23 (FcεRII). We will review the known and potential functions of IgE in health and disease: in particular, its detrimental roles in allergic diseases and chronic spontaneous urticaria, and its protective functions in host defense against parasites and venoms. Finally, we will present an overview of the drugs that are in clinical development or have therapeutic potential for IgE-mediated allergic diseases.

Biological characteristics of intestinal IgE and gut diseases

Immunoglobulin E (IgE), a crucial protective substance for the intestinal tract, plays an important role in gut immunity. IgE is secreted by plasma cells in the submucosal lamina propria upon antigenic invasion and, together with certain cytokines and immune cells, is involved in the regulation of gastrointestinal immunity in normal or abnormal conditions via the high affinity IgE receptor (FcεR I) and low affinity IgE receptor (CD23⁺). In this paper, we review the structure, synthetic transport, secretory regulation, receptor classification, and function of intestinal IgE as well as the related gut diseases.

Functional and phenotypic analysis of basophils allows determining distinct subtypes in patients with chronic urticaria

BACKGROUND

Chronic urticaria (CU) is a frequent skin disease characterized by relapsing appearance of pruritic hives. While clinical symptoms are due to the release of histamine by cutaneous mast cells, the underlying pathophysiology is still unknown. However, previous studies indicate that basophils might be of relevance. Besides, the occurrence of autoantibodies against IgE or its receptor, FcεRI, and the therapeutic efficacy of anti-IgE antibodies imply that IgE-mediated mechanisms also play an important role in CU.

METHODS

Reactivity of CU patients' peripheral blood basophils (n=60) to specific anti-FcεRI and IgE-independent fMLP stimulation was determined by basophil activation test in comparison with patients suffering from IgE-mediated allergic rhinitis (n=10) and healthy controls (n=10). In addition, immunoglobulin receptor (FcεRI, FcγRII) expression and surface bound antibodies (IgE, IgG) were quantified on basophils. Furthermore, the autoreactive capacity of CU sera was evaluated and urticaria-related symptoms were assessed by both UCT and CU-Q₂ oL.

RESULTS

Stimulating CU patients' basophils via FcεRI, we identified three distinct immunologic phenotypes. One subgroup of patients' basophils reacted to FcεRI stimulation, whereas the others had anti-FcεRI nonreactive basophils. Among the latter, a subgroup with pronounced basopenia was identified. Of note, this group was characterized by augmented serum-induced basophil activation, increased levels of autoantibodies against thyroid peroxidase, and also exhibited the strongest disease impact on their quality of life.

CONCLUSIONS

Patients with CU can be categorized into three immunologic subgroups based on their basophil reactivity and frequency. These phenotypes are associated with different clinical characteristics, pointing to basophils as important players in CU pathophysiology.

Proteomic Analysis of Antiprotease Immunoglobulin-E Anti-Sperm Autoantibodies in Chronic Urticaria After Vasectomy

Some types of chronic urticaria (CU) are associated with autoreactive immunoglobulin (Ig)E, as well as IgG. In the syndrome of autoimmune thyroid disease and CU, autoreactive IgE, as well as IgG against host thyroid tissue, is present. The author describes a patient with new onset of CU after vasectomy with evidence of both autoreactive IgE and IgG anti-sperm antibodies (ASA). Autoreactive sperm proteins are enzymes opposed to structural sperm antigens producing ASA in infertility and after anti-spermatocyte vaccines. The author suggests that autoreactive proteins with enzymatic activity either in host proteins, aeroallergens, or viral proteins may have increased propensity to generate autoreactive IgE. This model of autoimmune IgE ASA generation by sperm and other host enzymatic proteins in CU can be tested using proteomic technology. INTRODUCTION

Detection of circulating IgG autoantibody to FcεRIα in sera from chronic spontaneous urticaria patients

BACKGROUNDS

Chronic spontaneous urticaria (CSU) is a common skin disorder characterized by itchy wheals of at least 6 weeks in duration, wherein the autoimmune mechanism is involved to activate IgE receptors (FcεRIα) on mast cells. We aimed to assess levels of IgG autoantibody against FcεRIα in sera from CSU patients using dot-blot immunoassay.

METHODS

We performed a hospital-based cross-sectional study of 125 CSU patients (64 ASST-positive, 61 ASST-negative) and 64 age-and sex-matched healthy controls. The cut-off value of IgG FcεRIα autoantibody was determined as the mean intensity plus two standard deviations of values in controls. Positivity for IgG autoantibody to FcεRIα was analyzed according to clinical parameters of disease duration, urticaria activity score (UAS), ASST, response to antihistamine treatment, complement levels, and the presence of other autoantibodies. Nonparametric tests were applied for statistical analyses.

RESULTS

IgG positivity to FcεRIα was noted in 24.8% of CSU patients and was significantly more frequent in ASST-positive patients than in ASST-negative patients (32.8% vs 16.4%, P = 0.040). Only 3.1% of healthy controls had this autoantibody. Complement 3 levels were significantly lower in anti-FcεRIα antibody-positive patients than antibody-negative patients (109.8 ± 19.9 vs 123.1 ± 30.9, P = 0.035). No significant associations were found between IgG positivity to FcεRIα and UAS, serum total IgE levels, atopic status, clinical responses to antihistamines, or the presence of anti-thyroid and anti-nuclear antibodies.

CONCLUSION

These findings suggest that circulating IgG autoantibody to FcεRIα in a subset of patients may be involved in the autoimmune mechanism of CSU. Further studies are needed to clarify its clinical significance.

Chronic urticaria: a focus on pathogenesis

Chronic urticaria is a spontaneous or inducible group of diseases characterized by the occurrence of wheals (and, in about half of cases, angioedema) for more than 6 weeks. These are rather frequent conditions that may severely affect patients’ quality of life and sometimes represent a challenge for doctors as well. The causes of chronic urticaria are still poorly defined, although there is growing evidence that different biologic systems including immunity, inflammation, and coagulation may take part in the pathomechanism eventually leading to mast cell and basophil degranulation and hence to wheal formation. This review will discuss the main findings that are (slowly) shedding light on the pathogenesis of this disorder.

Advances in atopic dermatitis and urticarial in 2016

This review highlights recent key advances in the pathology and therapies of inflammatory skin diseases, focusing on atopic dermatitis (AD) and chronic spontaneous urticaria (CSU). Regarding AD, transcriptomic analysis with human samples revealed different immune profiles between childhood and adult AD. Phase III clinical trials of dupilumab, an anti-IL-4 receptor α antibody, in the treatment of AD have successfully finished, and dupilumab will appear in clinical practice as the first biologic for AD in 2017. In addition, a novel biologic that targets IL-31 shows promising results in a phase II trial. As for the skin microbiome study, novel insights into the mechanisms of microbial dysbiosis, such as colonization of Staphylococcus aureus, a common feature of AD, were proposed. Regarding CSU, autoreactive CD4⁺ T cells that react to FcεRI were discovered, which might contribute to the development of CSU. These findings provide new insights into the pathogenesis of AD and CSU and will lead to more specific and personalized treatments.