Anti-FcepsilonRIalpha autoantibodies in autoimmune-mediated disorders. Identification of a structure-function relationship

Association of autoantibodies with the IFN signature and NETosis in patients with systemic lupus erythematosus

Objective

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by a variety of disease symptoms and an unpredictable clinical course. To improve treatment outcome, stratification based on immunological manifestations commonly seen in patients with SLE such as autoantibodies, type I interferon (IFN) signature and neutrophil extracellular trap (NET) release may help. It is assumed that there is an association between these immunological phenomena, since NET release induces IFN production and IFN induces autoantibody formation via B-cell activation. Here we studied the association between autoantibodies, the IFN signature, NET release, and clinical manifestations in patients with SLE.

Methods

We performed principal component analysis (PCA) and hierarchical clustering of 57 SLE-related autoantibodies in 25 patients with SLE. We correlated each autoantibody to the IFN signature and NET inducing capacity.

Results

We observed two distinct clusters: one cluster contained mostly patients with a high IFN signature. Patients in this cluster often present with cutaneous lupus, and have higher anti-dsDNA concentrations. Another cluster contained a mix of patients with a high and low IFN signature. Patients with high and low NET inducing capacity were equally distributed between the clusters. Variance between the clusters is mainly driven by antibodies against histones, RibP2, RibP0, EphB2, RibP1, PCNA, dsDNA, and nucleosome. In addition, we found a trend towards increased concentrations of autoantibodies against EphB2, RibP1, and RNP70 in patients with an IFN signature. We found a negative correlation of NET inducing capacity with anti-FcER (r = -0.530; p = 0.007) and anti-PmScl100 (r = -0.445; p = 0.03).

Conclusion

We identified a subgroup of patients with an IFN signature that express increased concentrations of antibodies against DNA and RNA-binding proteins, which can be useful for further patient stratification and a more targeted therapy. We did not find positive associations between autoantibodies and NET inducing capacity. Our study further strengthens the evidence of a correlation between RNA-binding autoantibodies and the IFN signature.

Chronic Spontaneous Urticaria: Etiology and Pathogenesis

Urticaria, also known as hives, is a common condition thought to affect up to 20% of individuals worldwide in their lifetime. This skin condition is characterized by the appearance of pruritic, erythematous papules or plaques with superficial swelling of the dermis. The major complaint is the symptom of pruritus. Angioedema, which involves a deeper swelling of dermal or mucosal tissues, may accompany urticaria. Urticaria can be classified by both time course of symptoms and the underlying etiology.

Beyond the skin: B cells in pemphigus vulgaris, tolerance and treatment

Pemphigus vulgaris (PV) is a rare autoimmune bullous disease characterized by blistering of the skin and mucosa owing to the presence of autoantibodies against the desmosome proteins desmoglein 3 and occasionally in conjunction with desmoglein 1. Fundamental research into the pathogenesis of PV has revolutionized its treatment and outcome with rituximab, a B-cell-depleting therapy. The critical contribution of B cells to the pathogenesis of pemphigus is well accepted. However, the exact pathomechanism, mechanisms of onset, disease course and relapse remain unclear. In this narrative review, we provide an overview of the fundamental research progress that has unfolded over the past few centuries to give rise to current and emerging therapies. Furthermore, we summarize the multifaceted roles of B cells in PV, including their development, maturation and antibody activity. Finally, we explored how these various aspects of B-cell function contribute to disease pathogenesis and pave the way for innovative therapeutic interventions.

Research hotspots in urticaria: A bibliometric study of the top 100 most cited articles

BACKGROUND AND PURPOSE

Urticaria is a prevalent recurrent skin allergic condition. Severe itching significantly impacts patients' quality of life. This paper aims to investigate the development status of urticaria through bibliometric analysis to predict future research hotspots and trends.

METHODS

On October 29, 2023, a literature search was conducted in the Web of Science (WOS) database to collect urticaria-related publications. The top 100 most cited articles were charted, and VOSviewer software was utilized for the literature data analysis. A visual analysis was performed on the number of articles, journals, main researchers, keywords, and so on.

RESULTS

The research involved 415 authors from 28 countries, published across 25 journals, ranging from 1963 to 2023. Marcus Maurer was the leading author, with the United States being the foremost country in urticaria research. CEH Grattan received the most citations, and The Medical University of South Carolina had the highest number of publications. Key research focuses include epidemiology, pathogenesis, drug therapy, and quality of life assessments. "Anti-high affinity IgE receptor α chain (FcεRIα)," "chronic idiopathic urticaria," "autoantibodies," "histamine-release" emerged as the keywords with the highest prominence.

CONCLUSION

The field of urticaria research has attracted substantial attention over the past few decades, witnessing rapid development. This study highlighted the top 100 articles by citation frequency within the urticaria field. Bibliometric analysis revealed a shift in treatment methods from traditional antihistamines to biological agents, with significant emphasis on improving the quality of life in chronic urticaria management. These areas represent the current research focal points and indicate future trends in urticaria research.

Research progress in the pathogenesis of chronic urticaria

Chronic urticaria is very common in clinic, but its pathogenesis is not fully elucidated. Most patients can't find the exact cause, resulting in misdiagnosis or delayed treatment. Previous studies have found that mast cell activation is the central link in the pathogenesis of chronic urticaria. Genetics, autoimmune, coagulation disorders, and infection may also be involved in the pathophysiological process of chronic urticaria. With the deepening of research, more immune and non-immune mechanisms have been gradually revealed in the pathogenesis of chronic urticaria, such as the interaction of immune cells in the microenvironment of urticaria, intestinal flora and metabolism, neuroimmunity, environmental factors and hormones. Clarifying the pathogenesis of chronic urticaria will help to find more treatment targets and provide more diversified ideas for clinical diagnosis and treatment.

On the complexity of IgE: The role of structural flexibility and glycosylation for binding its receptors

It is well established that immunoglobulin E (IgE) plays a crucial role in atopy by binding to two types of Fcε receptors (FcεRI and FcεRII, also known as CD23). The cross-linking of FcεRI-bound IgE on effector cells, such as basophils and mast cells, initiates the allergic response. Conversely, the binding of IgE to CD23 modulates IgE serum levels and antigen presentation. In addition to binding to FcεRs, IgE can also interact with other receptors, such as certain galectins and, in mice, some FcγRs. The binding strength of IgE to its receptors is affected by its valency and glycosylation. While FcεRI shows reduced binding to IgE immune complexes (IgE-ICs), the binding to CD23 is enhanced. There is no evidence that galectins bind IgE-ICs. On the other hand, IgE glycosylation plays a crucial role in the binding to FcεRI and galectins, whereas the binding to CD23 seems to be independent of glycosylation. In this review, we will focus on receptors that bind to IgE and examine how the glycosylation and complexation of IgE impact their binding.

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.

Autoantibodies to IgE can induce the release of proinflammatory and vasoactive mediators from human cardiac mast cells

Mast cells are multifunctional immune cells with complex roles in tissue homeostasis and disease. Cardiac mast cells (HCMCs) are strategically located within the human myocardium, in atherosclerotic plaques, in proximity to nerves, and in the aortic valve. HCMCs express the high-affinity receptor (FcεRI) for IgE and can be activated by anti-IgE and anti-FcεRI. Autoantibodies to IgE and/or FcεRI have been found in the serum of patients with a variety of immune disorders. We have compared the effects of different preparations of IgG anti-IgE obtained from patients with atopic dermatitis (AD) with rabbit IgG anti-IgE on the release of preformed (histamine and tryptase) and lipid mediators [prostaglandin D₂ (PGD₂) and cysteinyl leukotriene C₄ (LTC₄)] from HCMCs. Functional human IgG anti-IgE from one out of six AD donors and rabbit IgG anti-IgE induced the release of preformed (histamine, tryptase) and de novo synthesized mediators (PGD₂ and LTC₄) from HCMCs. Human IgG anti-IgE was more potent than rabbit IgG anti-IgE in inducing proinflammatory mediators from HCMCs. Human monoclonal IgE was a competitive antagonist of both human and rabbit IgG anti-IgE. Although functional anti-IgE autoantibodies rarely occur in patients with AD, when present, they can powerfully activate the release of proinflammatory and vasoactive mediators from HCMCs.

IgG Autoantibodies Against IgE from Atopic Dermatitis Can Induce the Release of Cytokines and Proinflammatory Mediators from Basophils and Mast Cells

IgE-mediated release of proinflammatory mediators and cytokines from basophils and mast cells is a central event in allergic disorders. Several groups of investigators have demonstrated the presence of autoantibodies against IgE and/or FcεRI in patients with chronic spontaneous urticaria. By contrast, the prevalence and functional activity of anti-IgE autoantibodies in atopic dermatitis (AD) are largely unknown. We evaluated the ability of IgG anti-IgE from patients with AD to induce the in vitro IgE-dependent activation of human basophils and skin and lung mast cells. Different preparations of IgG anti-IgE purified from patients with AD and rabbit IgG anti-IgE were compared for their triggering effects on the in vitro release of histamine and type 2 cytokines (IL-4, IL-13) from basophils and of histamine and lipid mediators (prostaglandin D₂ and cysteinyl leukotriene C₄) from human skin and lung mast cells. One preparation of human IgG anti-IgE out of six patients with AD induced histamine release from basophils, skin and lung mast cells. This preparation of human IgG anti-IgE induced the secretion of cytokines and eicosanoids from basophils and mast cells, respectively. Human monoclonal IgE was a competitive antagonist of both human and rabbit IgG anti-IgE. Human anti-IgE was more potent than rabbit anti-IgE for IL-4 and IL-13 production by basophils and histamine, prostaglandin D₂ and leukotriene C₄ release from mast cells. Functional anti-IgE autoantibodies rarely occur in patients with AD. When present, they induce the release of proinflammatory mediators and cytokines from basophils and mast cells, thereby possibly contributing to sustained IgE-dependent inflammation in at least a subset of patients with this disorder.

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.

Cold urticaria in a pediatric cohort: Clinical characteristics, management, and natural history

BACKGROUND

Cold urticaria (coldU) is associated with substantial morbidity and risk of fatality. Data on coldU in children are sparse. We aimed to evaluate the clinical characteristics, management, risk of associated anaphylaxis, and resolution rate of coldU in a pediatric cohort. Additionally, we sought to compare these metrics to children with chronic spontaneous urticaria (CSU).

METHODS

We prospectively enrolled children with coldU from 2013-2021 in a cohort study at the Montreal Children's Hospital and an affiliated allergy clinic. Data for comparison with participants with solely CSU were extracted from a previous study. Data on demographics, comorbidities, severity of presentation, management, and laboratory values were collected at study entry. Patients were contacted yearly to assess for resolution.

RESULTS

Fifty-two children with cold urticaria were recruited, 51.9% were female and the median age of symptom onset was 9.5 years. Most patients were managed with second-generation H1-antihistamines (sgAHs). Well-controlled disease on sgAHs was negatively associated with concomitant CSU (adjusted odds ratio (aOR) = 0.69 [95%CI: 0.53, 0.92]). Elevated eosinophils were associated with cold-induced anaphylaxis (coldA; aOR = 1.38 [95%CI: 1.04, 1.83]), which occurred in 17.3% of patients. The resolution rate of coldU was 4.8 per 100 patient-years, which was lower than that of CSU (adjusted hazard ratio = 0.43 [95%CI: 0.21, 0.89], p < 10^-2 ).

CONCLUSION

Pediatric coldU bears a substantial risk of anaphylaxis and a low-resolution rate. Absolute eosinophil count and co-existing CSU may be useful predictive factors.

Development and Evaluation of an In-House ELISA to Detect Anti-FcεR1α IgG Autoantibodies in Chronic Spontaneous Urticaria Patients

Background

Association between chronic spontaneous urticaria (CSU) and autoimmunity has been well documented. Autologous serum skin testing could support the autoimmune etiology of CSU, whereas it is difficult to interpret and could not be performed on antihistamine omitted patients. It was found that immunoglobulin G (IgG) autoantibodies (autoAbs) against high-affinity IgE receptor (FcεR1) were suggested as a potential trigger in the pathogenesis of CSU. Although many ELISA protocols have been developed to detect these autoAbs, they lacked validation or a reliable cut-off point. We, therefore, aimed to develop a validated ELISA with a reliable cut-off point to quantitate IgG anti-FcεR1α autoAbs for CSU.

Methods

We developed an in-house ELISA to quantitate IgG anti-FcεR1α autoAbs. Sera from 233 CSU patients and 25 healthy people were used to test with ELISA. The cut-off point was obtained from the results subjected to analyze with receiver operating characteristic (ROC) analysis. ELISA was validated with 116 CSU patients and 150 healthy donors.

Results

ELISA revealed that healthy people had a basal level of IgG anti-FcεR1α autoAbs, whereas their levels were significantly lower than autoAbs levels in CSU patients. ROC analysis of ELISA determined the cut-off point at 936.7 ng/ml. Our ELISA was validated and provided excellent sensitivity and specificity at 98.28% and 92.67%, respectively.

Conclusion

Our ELISA could detect significant levels of IgG anti-FcεR1α autoAbs in CSU, supporting that these autoAbs were associated with CSU etiology. Our validated ELISA with the reliable cut-off point provided excellent accuracy at 95.11% (98.28% sensitivity and 92.67% specificity). Our ELISA could be an alternative test benefit for the patient who is unable to omit antihistamine treatment.

Autoimmune Pemphigus: Latest Advances and Emerging Therapies

Pemphigus represents a group of rare and severe autoimmune intra-epidermal blistering diseases affecting the skin and mucous membranes. These painful and debilitating diseases are driven by the production of autoantibodies that are mainly directed against the desmosomal adhesion proteins, desmoglein 3 (Dsg3) and desmoglein 1 (Dsg1). The search to define underlying triggers for anti-Dsg-antibody production has revealed genetic, environmental, and possible vaccine-driven factors, but our knowledge of the processes underlying disease initiation and pathology remains incomplete. Recent studies point to an important role of T cells in supporting auto-antibody production; yet the involvement of the myeloid compartment remains unexplored. Clinical management of pemphigus is beginning to move away from broad-spectrum immunosuppression and towards B-cell-targeted therapies, which reduce many patients’ symptoms but can have significant side effects. Here, we review the latest developments in our understanding of the predisposing factors/conditions of pemphigus, the underlying pathogenic mechanisms, and new and emerging therapies to treat these devastating diseases.

A novel detection method for cross-linking of IgE-receptors by autoantibodies in chronic spontaneous urticaria

BACKGROUND

Autoantibodies (AAbs) against immunoglobulin E (IgE) antibodies (Abs) and their high-affinity receptor alpha subunits (FcεRIα) are key factors in the elicitation of type IIb autoimmune chronic spontaneous urticaria (type IIb aiCSU). In this study, we aimed to develop a new method to detect functional anti-FcεRIα and anti-IgE AAbs, which can crosslink the plural FcεRІα molecules and IgE Abs on the surface of mast cells and basophils, in sera from aiCSU patients using the amplified luminescence proximity homogeneous assay (Alpha).

METHODS

Sera were obtained from 14 aiCSU patients, as diagnosed by recurrent chronic spontaneous urticaria episodes and positive results for the autologous serum skin test and/or histamine release test (HRT). The AAbs to FcεRIα and IgE Abs were determined in sera from aiCSU patients using enzyme-linked immunosorbent assay (ELISA) and Alpha by cross-linking (AlphaCL) of IgE Abs and/or FcεRІα.

RESULTS

Serum anti-FcεRIα and anti-IgE AAb levels were not significantly different between aiCSU patients and healthy subjects in ELISA. Anti-FcεRIα AAbs were detected in 10 of 14 aiCSU patients who displayed positive (5/5) and negative (5/9) results in the HRT for anti-FcεRIα AAbs by AlphaCL, whereas no signals were observed in healthy subjects. Additionally, anti-IgE AAbs were detected in two of four aiCSU patients who displayed positive results in the HRT for anti-IgE AAbs.

CONCLUSIONS

A new assay method using AlphaCL can detect anti-FcεRIα and anti-IgE AAbs with FcεRIα- and IgE-crosslinking abilities in sera from aiCSU patients. This simple and practical assay method may be available as a diagnostic tool for urticaria patients.

Fc receptors gone wrong: A comprehensive review of their roles in autoimmune and inflammatory diseases

Systemic autoimmune and inflammatory diseases have a complex and only partially known pathophysiology with various abnormalities involving all the components of the immune system. Among these components, antibodies, and especially autoantibodies are key elements contributing to autoimmunity. The interaction of antibody fragment crystallisable (Fc) and several distinct receptors, namely Fc receptors (FcRs), have gained much attention during the recent years, with possible major therapeutic perspectives for the future. The aim of this review is to comprehensively describe the known roles for FcRs (activating and inhibitory FcγRs, neonatal FcR [FcRn], FcαRI, FcεRs, Ro52/tripartite motif containing 21 [Ro52/TRIM21], FcδR, and the novel Fc receptor-like [FcRL] family) in systemic autoimmune and inflammatory disorders, namely rheumatoid arthritis, Sjögren's syndrome, systemic lupus erythematosus, systemic sclerosis, idiopathic inflammatory myopathies, mixed connective tissue disease, Crohn's disease, ulcerative colitis, immunoglobulin (Ig) A vasculitis, Behçet's disease, Kawasaki disease, IgG4-related disease, immune thrombocytopenia, autoimmune hemolytic anemia, antiphospholipid syndrome and heparin-induced thrombocytopenia.

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.

The impact of sex on susceptibility to systemic lupus erythematosus and rheumatoid arthritis; a bioinformatics point of view

The unknown etiology of systemic autoimmune diseases, such as Systemic Lupus Erythematosus (SLE) and Rheumatoid Arthritis (RA), with a remarkable predominance of female, have prompted many researchers for unveiling the precise molecular mechanisms involved in this gender bias. In fact, depending on hormones and transcribed genes from sex chromosomes, at least, the initial mechanisms involved in pathogenesis might differ largely. With the aim of elucidating the above mechanisms, we have tried to specify the differentially expressed genes (DEGs) extracted from microarray libraries from both female and male SLE and RA patients. Subsequently, the androgen and estrogen receptor elements (ARE and ERE) among differentially expressed transcription factors (TFs) and the DEGs located on X or Y chromosomes have been determined. Moreover, the pathways regarding the common DEGs in both sexes are enriched. Our data revealed several ARE and ERE-containing genes (LCN2, LTF, RPL31, RPL9, RPS17, RPS24, RPS27L, S100A8, ABCA1, HIST1H2BD, ISG15, MAFB, GNLY, EVL, and HDC) to be associated with the related autoimmune disease and sex. Also, two DEGs (KDM5D and RPS4Y1) in SLE patients were determined to be on Y chromosome with one had been proved to be associated with autoantigens in SLE. Altogether, our data showed a number of plausible pathways in both autoimmune conditions together with the relevance of several sex-related genes in the mentioned diseases pathogenesis.

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.

The Pathogenesis of Chronic Spontaneous Urticaria: The Role of Infiltrating Cells

Chronic spontaneous urticaria is characterized by a perivascular non-necrotizing cellular infiltrate around small venules of the skin. It consists primarily of CD4(+) lymphocytes, a prominence of the T helper (Th)2 subtype but also Th1 cells, with Th17 cell-derived cytokines elevated in plasma. There are also neutrophils, eosinophils, basophils, and monocytes. Chemokines derived from mast cells and activated endothelial cells drive the process. Although the role of the cellular infiltrate has not previously been addressed, each constituent can contribute to the overall pathogenesis. It is of interest that CSU responds to corticosteroid, yet, short-term steroids do not affect autoimmunity or degranulation of mast cells, and act on margination of cells along the endothelium and chemotaxis to enter the surrounding dermis. In this review, we address each cell's contribution to the overall inflammatory response, as it is currently understood, with a view toward development of therapeutic options that impede the function of critical cells and/or their secretory products.

Autoimmunity, IgE and FcεRI-bearing cells

Antibody-mediated autoimmune diseases (AAID) involve several isotypes of autoreactive antibodies. In a growing number of AAID, autoreactive IgE are present with a significant prevalence and are often associated with the presence of IgG anti-IgE and/or anti-FcεRIα (high affinity IgE receptor α chain). FcεRI-bearing cells, such as basophils or mast cells, are key players in some of these AAID. Recent advances in the pathophysiology of these diseases led to the passed or current development of anti-IgE strategies that showed very potent effects in some of them. The present review centralizes the information on the relevance of autoreactive IgE and FcεRI-bearing cells in the pathophysiology of different AAID and the ones where the anti-IgE therapeutic strategy shows or may show some benefits for the patients.

IgE in the Pathogenesis of SLE: From Pathogenic Role to Therapeutic Target

Systemic lupus erythematosus (SLE) is a multifactorial chronic autoimmune disease, marked by the presence of autoantibodies to nuclear antigens belonging to different isotype classes. For several years, IgE antibodies have been incriminated in the development of allergic diseases and parasitic infections and different anti-IgE therapies have been developed to encounter the pathogenic role of IgE in these pathologies. Recently, multiple studies showed the presence of elevated total IgE levels and demonstrated a pathogenic role of autoreactive IgE in SLE. This review aims to summarize the findings incriminating IgE and autoreactive IgE in the pathophysiology of SLE, to describe their functional outcomes on their targeted cells as well as to discuss different IgE-related therapeutic modalities that emerged and that may be beneficial for SLE patient care.

IgM and IgA in addition to IgG autoantibodies against FcɛRIα are frequent and associated with disease markers of chronic spontaneous urticaria

BACKGROUND

IgG autoantibodies against the high-affinity IgE receptor, FcɛRIα, contribute the pathogenesis of autoimmune chronic spontaneous urticaria (CSU). However, it is not known whether such patients also exhibit IgM or IgA autoantibodies against FcɛRIα. To address this question we developed an ELISA to assess serum levels of IgG, IgM, and IgA autoantibodies against FcɛRIα and investigated whether their presence is linked to clinical features of CSU including the response to autologous serum skin testing (ASST).

METHODS

Serum samples of 35 CSU patients (25 ASST-positive) and 52 healthy control individuals were analyzed using a newly developed competitive ELISA for IgG, IgM, and IgA autoantibodies to FcɛRIα.

RESULTS

One in four CSU patients (8/35, 24%) had elevated serum levels of IgG-anti-FcɛRIα compared with (3/52, 6%) healthy controls. More than half of patients had IgM (21/35, 60%) and IgA (20/35, 57%) vs (3/52, 5%) each in healthy controls. Elevated IgM, but not IgG or IgA, autoantibodies were significantly more frequent in ASST-positive CSU patients (18/25, 72%) compared with ASSTnegative patients (3/10, 33%, P = .022). Also, elevated levels of IgM-anti-FcɛRIα, but not of IgG or IgA against FcɛRIα, were linked to low blood basophil (r = .414, P = .021) and eosinophil (r = .623, P < .001) counts.

CONCLUSIONS

Increased serum levels of IgM-anti-FcɛRIα are common in patients with CSU and linked to features of autoimmune CSU. The role and relevance of autoantibodies to FcɛRIα in CSU can and should be further characterized in future studies, and our novel assay can help with this.

Effects of omalizumab on basophils: Potential biomarkers in asthma and chronic spontaneous urticaria

Omalizumab is an anti-IgE humanized monoclonal antibody approved for the treatment of severe asthma and chronic spontaneous urticaria. Omalizumab binds free serum IgE and antagonizes its interaction with FcεRI, which is considered the main pharmacodynamic mechanism responsible for the clinical response to the treatment. The reduction of IgE serum concentration down-regulates the cellular expression of FcεRI on basophils. However, the biological events occurring on basophils during the therapy with omalizumab are multiple and complex. Here we review the current evidence regarding the specific biological effects of omalizumab on basophils in patients with asthma and chronic spontaneous urticaria. In addition to the modulation of IgE receptors, omalizumab may affect basophils homeostasis, intra-cellular signaling, cellular responsiveness/activation and cytokine release. These effects may be partially responsible for the clinical success of omalizumab and potentially provide useful biological markers for future assessment of the clinical response to the treatment. However, further investigation is required to better elucidate the role of basophils during the treatment with omalizumab.

Presence of positive skin prick tests to inhalant allergens and markers of T2 inflammation in subjects with chronic spontaneous urticaria (CSU): a systematic literature review

BACKGROUND

Current guidelines do not recommend performing aeroallergen skin prick testing (SPT) in chronic spontaneous urticaria (CSU).

OBJECTIVE

The objective of this review was to investigate the presence of aeroallergen sensitization and markers of T2 inflammation in subjects with CSU.

METHODS

Systematic literature reviews to identify all studies that evaluated the presence of T2 markers of allergic inflammation in CSU subjects were performed.

RESULTS

In 16 studies that assessed the prevalence of positive SPT to multiple aeroallergens in CSU, 38.5% of CSU subjects had positive SPT. In three controlled studies, 34.2% of CSU subjects had positive SPT to multiple aeroallergens, compared to 13.6% of controls (p = 0.047). In 18 studies that assessed the prevalence of house dust mite (HDM) positive SPT in CSU, 27.5% of CSU subjects had positive SPT. In three controlled studies, 27.5% of CSU subjects had positive SPT to HDM, compared to 2.1% of controls (p = 0.047). Overall, CSU subjects were 3.1 times more likely to be aeroallergen-sensitized (95% CI 1.7-5.8, p = 0.0002) and 6.1 times more likely to be HDM-sensitized (95% CI 3.7-9.9, p < 0.00001) than controls. Mean total serum IgE (tIgE) levels were 238 kU/L and median tIgE levels were 164 kU/L, which was greater than the upper 90th percentile of normal (< 137 kU/L). Compared to healthy controls, CSU subjects were 6.5 times more likely to have IgG autoantibody against FcεR1α (p = 0.001), 2.4 times more likely to have IgG anti-IgE antibody (p = 0.03) and 5 times more likely to have anti-thyroid peroxidase (anti-TPO) antibody (p = 0.02). When corticosteroids were withheld for ≥ 28 days, mean blood eosinophil percentage was elevated at 5.9% (normal < 4%), but other studies reporting absolute count found the mean was in the normal range, 239 × 10 6 / L (normal < 400 × 10 6 / L).

CONCLUSION

Increased aeroallergen sensitization, tIgE, autoantibodies and blood eosinophil percentage in the CSU subjects indicates the possible importance of T2 inflammation in the pathogenesis of CSU. Further studies may be warranted to determine if specific allergen avoidance, desensitization or improvement in the mucosal allergic inflammation present in asthma and/or rhinitis has any benefit in the management of CSU.

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

Background

About one-half of all patients with chronic spontaneous urticaria have low or less reactivity of the basophils to FcεRI stimulation. However, the differences in the clinical characteristics between patients who show normal and attenuated basophil reactivities to FcεRI stimulation are still unclear. Furthermore, it also remains unknown as to what factors induce the poor reactivity of basophils to FcεRI stimulation.

Objective

The aim of the study is to investigate the differences in the clinical characteristics between patients who show normal and attenuated basophil reactivities to FcεRI stimulation.

Methods

We compared the clinical characteristics, including the autologous serum skin test-positive rates, serum concentrations of anti-IgE and anti-FcεRIα autoantibodies, and the FcεRI-crosslinking ability of these autoantibodies between patients with a negative basophil activation test (BAT) (≤10% CD203c^high basophils, n = 9) and positive BAT (>10% CD203c^high basophils, n = 13). We also monitored the changes in the 7-day urticaria activity scores after treatment with omalizumab, as compared to the score at the baseline, between the BAT-positive and BAT-negative patients.

Results

The BAT-negative patients showed a significantly higher urticaria control test score than the BAT-positive patients (p = 0.01). There were no significant differences in the autologous serum skin test-positive rates, concentrations of anti-IgE and anti-FcεRIα autoantibodies, and the FcεRI-crosslinking ability of these autoantibodies between the 2 groups. After treatment with omalizumab for 35 days, the score decreased to under 15 (corresponding to controlled or mild chronic spontaneous urticaria) in all of the BAT-negative patients, whereas in 6 out of the 13 BAT-positive patients, the scores remained over 16 (corresponding to moderate or severe chronic spontaneous urticaria).

Conclusions

The weak reactivity of basophils to FcεRI stimulation may not be due to the desensitization of basophils by anti-IgE or anti-FcεRIα autoantibodies. The time to response to omalizumab might differ between BAT-negative and BAT-positive patients with chronic spontaneous urticaria.

Comparison of tyrosinase antibody, tyrosinase-related protein-1 and -2 antibodies, melanin-concentrating hormone receptor antibody levels with autologous serum skin test and autologous plasma skin test results in patients with vitiligo

Introduction

Although the exact etiopathogenesis of vitiligo is unknown, the autoimmunity hypothesis is much in evidence. The autologous serum skin test (ASST) and autologous plasma skin test (APST) are in vivo methods used in the diagnosis of some autoimmune diseases, which are easy and inexpensive to perform.

Aim

In this study, we investigated whether or not ASST and APST could determine autoimmunity in patients with vitiligo.

Material and methods

In this study, 30 vitiligo patients presenting to the dermatology outpatient clinic and 30 healthy volunteers without any known autoimmune diseases were included. Antibodies such as tyrosinase, tyrosinase-related protein-1 (TYRP1), tyrosinase-related protein-2 (TYRP2) and melanin-concentrating hormone receptor 1 (MCHR1) antibodies determined to be associated with vitiligo were examined. In addition, the association of these antibodies with the positivity of ASST and APST, which were suggested to be associated with autoimmunity, were examined.

Results

In our study, tyrosinase antibody was found to be significantly higher in vitiligo patients. ASST was positive in 12 (40%) patients with vitiligo and 8 (26.6%) control subjects. APST was positive in 8 (26.6%) of the patients with vitiligo and in 2 (6.6%) of the controls, and there was a significant difference between the groups in terms of APST positivity (p = 0.032). In addition, in our study, a significant correlation was found between TYRP1 antibody positivity and APST positivity in the patient group (p = 0.005).

Conclusions

These findings suggest that we may use APST to investigate the autoimmune etiopathogenesis of vitiligo.

Paediatric severe chronic spontaneous urticaria: successful management through conventional drug therapy

Chronic spontaneous urticaria (CSU) can occur in children and the clinical management is quite challenging. Here, we described a paediatric clinical case of CSU successfully managed by conventional therapy, including systemic steroids, cetirizine, anti-leukotriene drug and dietary restriction (for histamine-releasing foods). This patient showed neither atopy nor any allergic sensitisation; moreover, the autologous serum skin test resulted negative. This category of patients with no comorbidity and no evidence of atopy might benefit from the conventional drug management; however, a protracted course of steroid treatment with very slow and gradual tapering may be needed. This approach was successful and safe in our clinical case, but a careful follow-up, due to the potential side effects of steroids, should be recommended.

Differentiation between control subjects and patients with chronic spontaneous urticaria based on the ability of anti-IgE autoantibodies (AAbs) to induce FcεRI crosslinking, as compared to anti-FcεRIα AAbs

BACKGROUND

The reported prevalences of IgG autoantibodies (AAbs) to FcεRIα and IgE in sera from patients with chronic spontaneous urticaria (CSU) have varied, and these AAbs are also often observed in healthy control subjects. Regarding the histamine release activity of purified IgG from patients with CSU, the number of examined patients has been small. Thus, we sought to determine the prevalence and FcεRI crosslinking ability of these AAbs in a large number of patients with CSU and non-atopic control (NC) subjects.

METHODS

We compared the concentrations of anti-IgE and anti-FcεRIα AAbs and the abilities of these AAbs to cause FcεRI aggregation in patients with CSU (n = 134) and NC subjects (n = 55) using ELISA and an in vitro elicitation test, respectively.

RESULTS

The concentration of anti-IgE AAbs was significantly different between the NC subjects and the CSU patients (P < 0.0001, cutoff value: 0.558 μg/mL), whereas the concentration of anti-FcεRIα AAbs was not. A significant difference in the duration of illness was noted between patients with lower and those with higher concentrations of anti-IgE AAbs relative to the cutoff value. The abilities of anti-IgE AAbs, but not anti-FcεRIα AAbs, to induce FcεRI crosslinking were significantly higher in CSU patients than in NC subjects (P = 0.0106).

CONCLUSIONS

In the Japanese population of CSU patients studied, the ability of the anti-IgE AAbs to induce FcεRI crosslinking differed significantly between NC subjects and CSU patients, suggesting the involvement of anti-IgE AAbs in the pathogenesis of CSU in the Japanese population.

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.

The Evolving Story of Autoantibodies in Pemphigus Vulgaris: Development of the "Super Compensation Hypothesis"

Emerging data and innovative technologies are re-shaping our understanding of the scope and specificity of the autoimmune response in Pemphigus vulgaris (PV), a prototypical humorally mediated autoimmune skin blistering disorder. Seminal studies identified the desmosomal proteins Desmoglein 3 and 1 (Dsg3 and Dsg1), cadherin family proteins which function to maintain cell adhesion, as the primary targets of pathogenic autoAbs. Consequently, pathogenesis in PV has primarily considered to be the result of anti-Dsg autoAbs alone. However, accumulating data suggesting that anti-Dsg autoAbs by themselves cannot adequately explain the loss of cell-cell adhesion seen in PV, nor account for the disease heterogeneity exhibited across PV patients has spurred the notion that additional autoAb specificities may contribute to disease. To investigate the role of non-Dsg autoAbs in PV, an increasing number of studies have attempted to characterize additional targets of PV autoAbs. The recent advent of protein microarray technology, which allows for the rapid, highly sensitive, and multiplexed assessment of autoAb specificity has facilitated the comprehensive classification of the scope and specificity of the autoAb response in PV. Such detailed deconstruction of the autoimmune response in PV, beyond simply tracking anti-Dsg autoAbs, has provided invaluable new insights concerning disease mechanisms and enhanced disease classification which could directly translate into superior tools for prognostics and clinical management, as well as the development of novel, disease specific treatments.

Non-Desmoglein Antibodies in Patients With Pemphigus Vulgaris

Pemphigus vulgaris (PV) is a potentially life-threatening mucocutaneous autoimmune blistering disease. Patients develop non-healing erosions and blisters due to cell–cell detachment of keratinocytes (acantholysis), with subsequent suprabasal intraepidermal splitting. Identified almost 30 years ago, desmoglein-3 (Dsg3), a Ca²⁺-dependent cell adhesion molecule belonging to the cadherin family, has been considered the “primary” autoantigen in PV. Proteomic studies have identified numerous autoantibodies in patients with PV that have known roles in the physiology and cell adhesion of keratinocytes. Antibodies to these autoantibodies include desmocollins 1 and 3, several muscarinic and nicotinic acetylcholine receptor subtypes, mitochondrial proteins, human leukocyte antigen molecules, thyroid peroxidase, and hSPCA1—the Ca²⁺/Mn²⁺-ATPase encoded by ATP2C1, which is mutated in Hailey–Hailey disease. Several studies have identified direct pathogenic roles of these proteins, or synergistic roles when combined with Dsg3. We review the role of these direct and indirect mechanisms of non-desmoglein autoantibodies in the pathogenesis of PV.

Successful Treatment of Autoimmune Urticaria with Low-Dose Prednisolone Therapy Administered for a Few Months: A Case Series of 42 Patients

BACKGROUND

Chronic spontaneous urticaria (CSU) is defined as symptoms of urticaria persisting for 6 weeks or more without obvious cause. Autologous serum skin test (ASST) positivity in patients with CSU is considered to be associated with autoimmune urticaria (AIU).

METHODS

In this retrospective study we retrieved the medical records of 1,073 urticaria patients seen at the Department of Dermatology and Allergology of Szeged University between January 2005 and February 2014. Forty-two patients (36 female and 6 male) met the study criteria by having CSU and giving positive results in the ASST. Our aim was to assess the clinical efficacy and safety of low-dose oral prednisolone therapy administered to patients with antihistamine-refractory ASST-positive CSU for a few months. Patients were given an initial dose (40 mg/day) of prednisolone until the complete resolution of the symptoms, usually 7-10 days, and then the dose was gradually decreased, as in other autoimmune diseases.

RESULTS

Prednisolone therapy lasted for an average of 3.6 months and a complete long-lasting response was achieved in 35 of 42 AIU patients (83.3%). The follow-up period was at least 36 months (3 years) for each AIU patient; the longest follow-up time was 139 months (11.5 years). None of the patients reported any considerable side effects.

CONCLUSION

Based on our results, we suggest that the use of this treatment could be an alternative for the treatment of AIU. Our present results also highlight the need for other therapies in a small percentage of AIU patients. Our results suggest that AIU represents a transient autoimmunity that can be successfully treated with low-dose steroid therapy administered for a few months.

Potential blood biomarkers in chronic spontaneous urticaria

Chronic spontaneous urticaria (CSU) is a mast cell-driven disease that is defined as the recurrence of weals, angioedema or both for > 6 weeks due to known or unknown causes. As of yet, disease diagnosis is purely clinical. Objective tools are needed to monitor the activity of CSU and the efficacy of treatment. Recently, several reports have suggested that blood parameters may be considered as potential disease-related biomarkers. Here, we reviewed available literature on blood biomarkers for CSU diagnosis, activity monitoring, duration, patient subgroup allocation or response to treatment. We performed a PubMed, Google Scholar and Web of Science search and identified and analysed 151 reports published prior to January 2016. We found strong evidence for significant differences between patients with CSU and healthy controls in blood levels or values of D-dimer, C-reactive protein (CRP), matrix metalloproteinase-9 (MMP-9), mean platelet volume (MPV), factor VIIa, prothrombin fragment 1 + 2 (F1 + 2), tumour necrosis factor, dehydroepiandrosterone sulphate and vitamin D. Also, there is strong evidence for a significant association between CSU activity and blood levels or values of D-dimer, F1 + 2, CRP, IL-6 and MPV. Strong evidence for reduced basophil count and high levels of IgG anti-FcεRI in the subgroup of CSU patients with positive autologous serum skin test was shown. In contrast, the evidence for all reported blood biomarkers for differentiating CSU from other diseases, or a role in prognosis, is weak, inconsistent or non-existent. Taken together, we identified 10 biomarkers that are supported by strong evidence for distinguishing patients with CSU from healthy controls, or for measuring CSU activity. There is a need for further research to identify biomarkers that predict outcome or treatment response in CSU.

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.

Mechanisms of action that contribute to efficacy of omalizumab in chronic spontaneous urticaria

The monoclonal anti-immunoglobulin E (IgE) antibody, omalizumab, was the first drug approved for use in patients with chronic idiopathic/spontaneous urticaria (CIU/CSU) who remain symptomatic despite H₁ -antihistamine treatment. Omalizumab binds to free IgE, which lowers free IgE levels and causes FcεRI receptors on basophils and mast cells to be downregulated. It has been shown to improve symptoms of CIU/CSU, but its mechanism of action is not currently understood. Potential mechanisms in CIU/CSU include reducing mast cell releasability, reversing basopenia and improving basophil IgE receptor function, reducing activity of IgG autoantibodies against FcεRI and IgE, reducing activity of IgE autoantibodies against an antigen or autoantigen that has yet to be definitively identified, reducing the activity of intrinsically 'abnormal' IgE, and decreasing in vitro coagulation abnormalities associated with disease activity. However, none of these theories alone or in combination fully account for the pattern of symptom improvement seen with omalizumab therapy, and therefore, no one mechanism is likely to be the definitive mechanism of action. Additional research is needed to further clarify the involvement of omalizumab in relieving symptoms associated with the complex, multifactorial pathogenesis of CIU/CSU.

Basophil markers for identification and activation in the indirect basophil activation test by flow cytometry for diagnosis of autoimmune urticaria

Background

The indirect basophil activation test using flow cytometry is a promising tool for autoimmune urticaria diagnosis. We aimed to identify better donor basophils (from atopic vs. non-atopic donors and interleukin-3 primed vs. unprimed basophils) and improve basophil identification and activation markers (eotaxin CC chemokine receptor-3 [CCR3] vs. CD123 and CD63 vs. CD203c).

Methods

Donor basophils were obtained from non-atopic and atopic group O donors. Positive control sera were artificially prepared to simulate autoimmune urticaria patients' sera. Patient sera were obtained from nine children with chronic urticaria. Assay sensitivity was compared among each variation by using positive control sera (n=21), applying cutoff values defined from negative control sera (n=20).

Results

For basophil identification, a combination of CCR3 and CD123 markers revealed a higher correlation with automated complete blood count (r=0.530) compared with that observed using CD123 (r=0.498) or CCR3 alone (r=0.195). Three activation markers on the atopic donor basophils attained 100% assay sensitivity: CD203c on unprimed basophils, CD63+CD203+ or CD63 alone on primed basophils; however, these markers on the non-atopic donor basophils attained lower assay sensitivity.

Conclusions

For basophil identification markers, a combination of CD123 and CCR3 is recommended, while CD123 alone may be used as an alternative. Donor basophils should be obtained from an atopic donor. For basophil activation markers, either CD203c alone on unprimed basophils or CD203c and CD63 on primed basophils are recommended, while CD63 alone on primed basophils may be used as an alternative.

Looking forward to new targeted treatments for chronic spontaneous urticaria

The introduction of omalizumab to the management of chronic spontaneous urticaria (CSU) has markedly improved the therapeutic possibilities for both, patients and physicians dealing with this disabling disease. But there is still a hard core of patients who do not tolerate or benefit from existing therapies and who require effective treatment. Novel approaches include the use of currently available drugs off-licence, investigational drugs currently undergoing clinical trials and exploring the potential for therapies directed at pathophysiological targets in CSU. Off-licence uses of currently available drugs include rituximab and tumour necrosis factor inhibitors. Ligelizumab (anti-IgE), canakinumab (anti-IL-1), AZD1981 (a PGD2 receptor antagonist) and GSK 2646264 (a selective Syk inhibitor) are currently in clinical trials for CSU. Examples of drugs that could target potential pathophysiological targets in CSU include substance P antagonists, designed ankyrin repeat proteins, C5a/C5a receptor inhibitors, anti-IL-4, anti-IL-5 and anti-IL-13 and drugs that target inhibitory mast cell receptors. Other mediators and receptors of likely pathogenic relevance should be explored in skin profiling and functional proof of concept studies. The exploration of novel therapeutic targets for their role and relevance in CSU should help to achieve a better understanding of its etiopathogenesis.

Isolation of Natural Anti-FcεRIα Autoantibodies from Healthy Donors

Natural antibodies are defined as antibodies detected in a healthy individual without active immunization. These antibodies are specific for exoantigens, as well as for autoantigens, mostly without any pathogenic role. Most of the studies conducted with natural (auto-) antibodies have been performed using affinity purified antibodies from individual sera or polyclonal Ig-preparations such as Intravenous Ig (IVIg). For in-depth analysis of such autoantibodies affinity-purified Ig-preparations from healthy individuals are of no use, as they are oligoclonal or polyclonal. Thus, there is a need of human monoclonal autoantibodies. Human monoclonal autoantibodies can be produced from B cells isolated from humans; however, this requires the screening of a large number of antibodies to identify one among them specific to an antigen. Using the phage display technology we generated such autoantibodies against the alpha subunit of the high-affinity IgE receptor (FcεRIα). Here we describe the step-by-step protocol for the generation of such libraries and the isolation of autoantibodies by affinity panning.

IgE-Related Chronic Diseases and Anti-IgE-Based Treatments

IgE is an immunoglobulin that plays a central role in acute allergic reactions and chronic inflammatory allergic diseases. The development of a drug able to neutralize this antibody represents a breakthrough in the treatment of inflammatory pathologies with a probable allergic basis. This review focuses on IgE-related chronic diseases, such as allergic asthma and chronic urticaria (CU), and on the role of the anti-IgE monoclonal antibody, omalizumab, in their treatment. We also assess the off-label use of omalizumab for other pathologies associated with IgE and report the latest findings concerning this drug and other new related drugs. To date, omalizumab has only been approved for severe allergic asthma and unresponsive chronic urticaria treatments. In allergic asthma, omalizumab has demonstrated its efficacy in reducing the dose of inhaled corticosteroids required by patients, decreasing the number of asthma exacerbations, and limiting the effect on airway remodeling. In CU, omalizumab treatment rapidly improves symptoms and in some cases achieves complete disease remission. In systemic mastocytosis, omalizumab also improves symptoms and its prophylactic use to prevent anaphylactic reactions has also been discussed. In other pathologies such as atopic dermatitis, food allergy, allergic rhinitis, nasal polyposis, and keratoconjunctivitis, omalizumab significantly improves clinical manifestations. Omalizumab acts in two ways: by sequestering free IgE and by accelerating the dissociation of the IgE-Fcε receptor I complex.

Comorbidity and pathogenic links of chronic spontaneous urticaria and systemic lupus erythematosus--a systematic review

Chronic spontaneous urticaria (CSU) is a common mast cell-driven disease characterized by the development of wheals (hives), angioedema (AE), or both for > 6 weeks. It is thought that autoimmunity is a common cause of CSU, which is often associated with autoimmune thyroiditis, whereas the link to other autoimmune disorders such as systemic lupus erythematosus (SLE) has not been carefully explored. Here, we systematically reviewed the existing literature for information on the prevalence of CSU in SLE (and vice versa) and we examined the possible clinical and pathogenetic relationship between CSU and SLE. The prevalence of CSU and CSU-like rash in SLE was investigated by 42 independent studies and comorbidity in adult patients reportedly ranged from 0% to 21.9% and 0.4% to 27.5%, respectively (urticarial vasculitis: 0-20%). In children with SLE, CSU was reported in 0-1.2% and CSU-like rash in 4.5-12% (urticarial vasculitis: 0-2.2%). In contrast, little information is available on the prevalence of SLE in patients with CSU, and more studies are needed to determine the rate of comorbidity. Recent insights on IgG- and IgE-mediated autoreactivity suggest similarities in the pathogenesis of CSU and SLE linking inflammation and autoimmunity with the activation of the complement and coagulation system. Future studies of patients with either or both conditions could help to better define common pathomechanisms in CSU and SLE and to develop novel targeted treatment options for patients with CSU and SLE.

Diagnostic and Therapeutic Iter in Chronic Urticaria Patients

We describe a diagnostic and therapeutic protocol for the management of chronic urticaria. It is derived from an extensive review of current literature, with a cost-effective evaluation of laboratory investigations and therapeutic approaches. Our protocol may not represent a cornerstone for chronic urticaria: much has in fact to be clarified on pathogenetic mechanisms and aetiological factors. Nevertheless, its application should be able, in our opinion, to identify what is useful or not in the everyday management of chronic urticaria patients.