Autoallergy in atopic dermatitis

Transcriptomic evaluation of skin tape-strips in children with allergic asthma uncovers epidermal barrier dysfunction and asthma-associated biomarkers abnormalities

INTRODUCTION

Tape-strips, a minimally invasive method validated for the evaluation of several skin diseases, may help identify asthma-specific biomarkers in the skin of children with allergic asthma.

METHODS

Skin tape-strips were obtained and analyzed with RNA-Seq from children with moderate allergic asthma (MAA) (n = 11, mean age 7.00; SD = 1.67), severe allergic asthma (SAA) (n = 9, mean age 9.11; SD = 2.37), and healthy controls (HCs) (n = 12, mean age 7.36; SD = 2.03). Differentially expressed genes (DEGs) were identified by fold change ≥2 with a false discovery rate <0.05. Transcriptomic biomarkers were analyzed for their accuracy in distinguishing asthma from HCs, their relationships with asthma-related outcomes (exacerbation rate, lung function-FEV1, IOS-R5-20, and lung inflammation-FeNO), and their links to skin (barrier and immune response) and lung (remodeling, metabolism, aging) pathogenetic pathways.

RESULTS

RNA-Seq captured 1113 in MAA and 2117 DEGs in SAA. Epidermal transcriptomic biomarkers for terminal differentiation (FLG/filaggrin), cell adhesion (CDH19, JAM2), lipid biosynthesis/metabolism (ACOT2, LOXL2) were significantly downregulated. Gene set variation analysis revealed enrichment of Th1/IFNγ pathways (p < .01). MAA and SAA shared downregulation of G-protein-coupled receptor (OR4A16, TAS1R3), upregulation of TGF-β/ErbB signaling-related (ACVR1B, EGFR, ID1/2), and upregulation of mitochondrial-related (HIGD2A, VDAC3, NDUFB9) genes. Skin transcriptomic biomarkers correlated with the annualized exacerbation rate and with lung function parameters. A two-gene classifier (TSSC4-FAM212B) was able to differentiate asthma from HCs with 100% accuracy.

CONCLUSION

Tape-strips detected epithelial barrier and asthma-associated signatures in normal-appearing skin from children with allergic asthma and may serve as an alternative to invasive approaches for evaluating asthma endotypes.

From neglect to spotlight: the underappreciated role of B cells in cutaneous inflammatory diseases

The skin, covering our entire body as its largest organ, manifests enormous complexities and a profound interplay of systemic and local responses. In this heterogeneous domain, B cells were considered strangers. Yet, recent studies have highlighted their existence in the skin and their distinct role in modulating cutaneous immunity across various immune contexts. Accumulating evidence is progressively shedding light on the significance of B cells in maintaining skin health and in skin disorders. Herein, we integrate current insights on the systemic and local contributions of B cells in three prevalent inflammatory skin conditions: Pemphigus Vulgaris (PV), Systemic Lupus Erythematosus (SLE), and Atopic Dermatitis (AD), underscoring the previously underappreciated importance of B cells within skin immunity. Moreover, we address the potential adverse effects of current treatments used for skin diseases, emphasizing their unintentional consequences on B cells. These comprehensive approaches may pave the way for innovative therapeutic strategies that effectively address the intricate nature of skin disorders.

Clinical and immunological characteristics of TGM3 in pan-cancer: A potential prognostic biomarker

Background: Recent studies have identified that transglutaminases (TGMs) are involved in a widespread epigenetic modification in tumorigenesis. However, it remains unclear how transglutaminase 3 (TGM3) affects in pan-cancer. The present study aimed to explore the clinical and prognostic function of TGM3 in pan-cancer as well as to explore the relationship of TGM3 expression with clinical stage, survival rate, prognosis condition, immune infiltration and mutation indicators. Methods: The relevant data of tumors were obtained from The Cancer Genome Atlas (TCGA), TARGET, Cancer Cell Line Encyclopedia (CCLE) and Genotype-Tissue Expression (GTEx) databases. According to the Human Protein Atlas (HPA) and TIMER databases, we evaluated the protein expression levels of TGM3 in different organs and tissues as well as their association with immune cell infiltration and immunotherapeutic response in pan-cancers. Expression differences between normal and tumor tissues as well as survival and prognosis situation, clinical data characteristics, tumor mutational burden (TMB), microsatellite instability (MSI), and RNA methylation were also assessed. Oncogenic analyses were also evaluated by GSEA. Results: Compared to normal tissues, some tumor tissues had a lower expression level of TGM3, while other tumor tissues had a high expression level of TGM3. Further studies showed that high TGM3 expression had a certain risk impact on pan-cancer as high TGM3 expression levels were detrimental to the survival of several cancers, except for pancreatic cancer (PAAD). High expression level of TGM3 was also related to higher clinical stages in most cancers. The expression level of TGM3 was significantly negatively correlated with the expression of immune infiltration-related cells, including B cells, CD8+ T cells, CD4+ T cells, neutrophils, macrophages and dendritic cells (DCs). Furthermore, in most cancer types, TGM3 was inversely correlated with TMB, MSI, and methylation, suggesting that TGM3 expression can be used to assess potential therapeutic response, especially immune-related targeted therapy. GSEA analysis elucidated the biological and molecular function of TGM3 in various cancer types. Taken together, these bioinformatic analyses identified TGM3 as an important biomarker for clinical tumor prognosis and evaluation of treatment efficacy. Conclusion: We comprehensively analyzed the clinical characteristics, tumor stages, immune infiltration, methylation level, gene mutation, functional enrichment analysis and immunotherapeutic value of TGM3 in pan-cancer, providing implications for the function of TGM3 and its role in clinical treatment.

Regulatory T cells and immunoglobulin E: A new therapeutic link for autoimmunity?

Autoimmune diseases have a prevalence of approximately 7 to 9% and are classified as either organ-specific diseases, including type I diabetes, multiple sclerosis, inflammatory bowel disease and myasthenia gravis, or systemic diseases, including systemic lupus erythematosus, rheumatoid arthritis and Sjögren's syndrome. While many advancements have been made in understanding of the mechanisms of autoimmune disease, including the nature of self-tolerance and its breakdown, there remain unmet needs in terms of effective and highly targeted treatments. T regulatory cells (Tregs) are key mediators of peripheral tolerance and are implicated in many autoimmune diseases, either as a result of reduced numbers or altered function. Tregs may be broadly divided into those generated in the thymus (tTregs) and those generated in the periphery (pTregs). Tregs target many different immune cell subsets and tissues to suppress excessive inflammation and to support tissue repair and homeostasis: there is a fine balance between Treg cell stability and the plasticity that is required to adjust Tregs' regulatory purposes to particular immune responses. The central role of immunoglobulin E (IgE) in allergic disease is well recognized, and it is becoming increasingly apparent that this immunoglobulin also has a wider role encompassing other diseases including autoimmune disease. Anti-IgE treatment restores the capacity of plasmacytoid dendritic cells (pDCs) impaired by IgE- high-affinity IgE receptor (FcεR1) cross-linking to induce Tregs in vitro in atopic patients. The finding that anti-IgE therapy restores Treg cell homeostasis, and that this mechanism is associated with clinical improvement in asthma and chronic spontaneous urticaria suggests that anti-IgE therapy may also have a potential role in the treatment of autoimmune diseases in which Tregs are involved.

Chronic urticaria associated with lung adenocarcinoma — a paraneoplastic manifestation: A case report and literature review

BACKGROUND

Urticaria is one of the most common causes of emergency room visits. It is defined as an acute inflammatory dermatosis, characterized by localized degranulation of mast cells, with consequent dermal microvascular and formation of edematous and pruritic plaques called hives. Urticaria affects the skin and tissues of the superficial mucosa. Sometimes it is accompanied by angioedema, which is characterized by deeper edema of the dermis and subcutaneous cellular tissue known as the urticarial-angioedema syndrome. About 15%-25% of the general population has suffered at least one type of urticaria at some point during their lifetime and hyperpermeability estimated at 7.6%-16% and has experienced acute urticaria that is usually self-limited and spontaneously resolves without requiring medical attention.

CASE SUMMARY

We present the case of a young male patient who was referred to our department with a clinical picture of 4 mo of pruritus associated with hives of variable sizes, irregular borders, with interlesional confluence, that were non-painful, without involvement of the palms and soles of the feet but with a tendency to progression in a generalized manner. He had multiple emergency room visits and poor response to antihistamines and systemic corticosteroids. Imaging studies demonstrated nodules in the lower lingula segment, at the level of the greater fissure and in the anterior contour of the left anterior basal segment associated with parahiliar adenopathies in the absence of findings suggestive of infectious or autoimmune etiology. Segmental lobectomy was performed by thoracoscopy with resection of a lung nodule in the lingula and biopsy of the para-aortic mediastinal ganglion. The histopathological report showed the presence of poorly differentiated invasive adenocarcinoma with a solid morphological and acinar pattern with immunohistochemical description of lung tissue that expresses strong positive and diffuse reaction for thyroid transcription factor 1 (TTF-1) with negativity to P40 for a histopathological diagnosis of malignant epithelial neoplasia with expression of infiltrating adenocarcinoma. Spontaneous chronic urticaria is considered possibly secondary to lung adenocarcinoma.

CONCLUSION

Chronic spontaneous urticaria is considered a paraneoplastic dermatosis with a controversial association in the literature. In the presented case, a young patient presented with chronic refractory urticaria and after an exhaustive clinical work-up was found to have a diagnosis of poorly differentiated lung adenocarcinoma with high expression of TTF-1. According to the Curth criteria, the urticaria presented by the patient is related to the oncological diagnosis. In addition, the high expression of TTF-1 documented in this case could be acting as an autoantigen that would cause chronic spontaneous urticaria. Further research evaluating a causal relationship between the TFF-1 protein and urticaria in lung cancer is needed.

Immunoglobulin E response in health and disease beyond allergic disorders

Immunoglobulin E is the latest discovered of immunoglobulin family and has been long associated with anaphylaxis and worm expulsion. Immunoglobulin E, along with mast cells, basophils, and eosinophils, is also a hallmark of type 2 immunity which is dysregulated in numerous diseases such as asthma, rhinitis, atopic dermatitis, and eosinophilic esophagitis in addition to anaphylaxis as aforementioned. However, recent advances have shed light on IgE regulation and memory explaining the low level of free IgE, the scarcity of IgE plasma cells that are mainly short live and the absence of IgE memory B cells in homeostatic conditions. Furthermore, IgE was implicated in inflammatory conditions beyond allergic disorders where IgE-mediated facilitated antigen presentation can enhance cellular and humoral response against autoantigens in systemic lupus or chronic urticaria leading to more severe disease and even against neoantigen facilitating tumor cell lysis. At last, IgE was unexpectedly associated with allograft rejection or atheromatous cardiovascular diseases where precise mechanisms remain to be deciphered. The purpose of this review is to summarize these recent advances in IgE regulation, biology, and physiopathology beyond allergic diseases opening whole new fields of IgE biology to explore.

Targeting therapeutic approaches and highlighting the potential role of nanotechnology in atopic dermatitis

Atopic dermatitis is a chronic as well as widespread skin disease which has significant influence on the life attributes of affected people and their families. Systemic immunosuppressive drugs can be utilised for effective care of disease, although they are often prescribed for rigorous disruption or disease that is complicated to manage. Therefore, topical applications of corticosteroids are considered the primary pharmacologic therapies for atopic dermatitis, and research recommends that these medications might be helpful in preventing disease flare-ups. However, topical medicine administration to deeper layers of skin is challenging because of the skin anatomic barrier that restricts deeper drug permeation, and also due to barrier function abnormalities in atopic dermatitis skin, which might result in systemic drug absorption, provoking systemic consequences. Hence, effective management of atopic dermatitis needs new, effective, safe and targeted treatments. Therefore, nanotechnology-based topical therapeutics have attracted much interest nowadays because of their tendency to increase drug diffusion and bioavailability along with enormous drug targeting potential to affected cells, and, thereby, reducing the adverse effects of medications. In this review, we mention different symptoms of atopic dermatitis, and provide an overview of the different triggering factors causing atopic dermatitis, with emphasis on its epidemiology, pathophysiology, clinical features and diagnostic, and preventive measures. This review discusses existing therapeutics for treating atopic dermatitis, and the newer approaches as well as the current classical pharmacotherapy of atopic dermatitis against new nanoparticle skin delivery systems. This review has also briefly summarised the recent patents and clinical status of therapeutic modalities for atopic dermatitis.

Specific T cells targeting Staphylococcus aureus fibronectin-binding protein 1 induce a type 2/type 1 inflammatory response in sensitized atopic dermatitis patients

BACKGROUND

Atopic dermatitis (AD) is one of the most common inflammatory skin diseases worldwide and Staphylococcus aureus colonization and secondary infections occur in the majority of AD patients. Allergic sensitizations against microbial antigens have been discussed as possible trigger factors of AD. Recently, we reported IgE sensitization against fibronectin-binding protein 1 (FBP1), an essential virulence component in S. aureus, in a subgroup of patients suffering from AD. To expand these findings by investigating delayed-type immune reactions, the objective of this study was to detect and phenotypically characterize FBP1-specific T cells as possible trigger factors in AD.

METHODS

Immunodominant T-cell epitopes were mapped by proliferation testing of patient-derived FBP1-specific T-cell lines after stimulation with single 15mer peptides, which were derived from different functional domains of the FBP1 sequence. Major histocompatibility complex class II tetramers carrying immunodominant epitopes successfully stained T helper cells in 8 out of 8 HLA-matched, IgE-sensitized AD patients.

RESULTS

Cytokine profiling of multimer-sorted cells revealed that predominantly the type 2 cytokines IL-13 and IL-4 were secreted by these cells. In contrast, IL-17, the marker cytokine for response to extracellular pathogens, was scarcely detectable.

CONCLUSIONS

We demonstrate that FBP1 contains immunodominant peptides that induce a specific pro-inflammatory T helper cell response with increased Th2 levels that can drive an allergic inflammation in sensitized AD patients.

Pollens in therapeutic/diagnostic systems and immune system targeting

Pollen is an excellent natural substance that plays an essential role in the reproduction of plants. In this review, we explain the structure, compositions, and characteristics of pollens. We consider pollen as a multifunctional tool that can be used in therapeutic/diagnostic systems. This microcapsule can be used in the forms of the hollow microcapsule, microgel, and composite, and also can be a tool for the synthesis of micro/nanostructures in various medical applications and used for the production of genetically modified plants that affect human health. In addition, we investigate the capability of this multifunctional tool in the immune system targeting that acts as an immunomodulator. In all applications and capabilities, we explain the potential of using nanostructures as parts of these systems and as auxiliary tools for promoting the applications of pollen. It is expected that soon, with the help of pollen-based therapeutic/diagnostic systems with the ability to immune system targeting, we will achieve effective and targeted therapeutic systems for the treatment of inflammatory and autoimmune diseases. In this paper, we suggest some ideas that may be a new step for future researches.

Physiological mechanisms of unexplained (functional) gastrointestinal disorders

Functional gastrointestinal disorders (FGIDs) encompass a range of complex conditions with similar clinical characteristics and no overt pathology. Recent recognition of sub-clinical pathologies in FGIDs, in conjunction with physiological and biochemical abnormalities including increased intestinal permeability, microbial profile alterations, differences in metabolites and extra-intestinal manifestations of disease, call into question the designation of these conditions as 'functional'. This is despite significant heterogeneity in both symptom profile and specifics of reported physiological abnormalities hampering efforts to determine defined mechanisms that drive onset and chronicity of symptoms. Instead, the literature demonstrates these conditions are disorders of homeostatic imbalance, with disruptions in both host and microbial function and metabolism. This imbalance is also associated with extraintestinal abnormalities including psychological comorbidities and fatigue that may be a consequence of gastrointestinal disruption. Given the exploitation of such abnormalities will be crucial for improved therapeutic selection, an enhanced understanding of the relationship between alterations in function of the gastrointestinal tract and the response of the immune system is of interest in identifying mechanisms that drive FGID onset and chronicity. Considerations for future research should include the role of sex hormones in regulating physiological functions and treatment responses in patients, as well as the importance of high-level phenotyping of clinical, immune, microbial and physiological parameters in study cohorts. There is opportunity to examine the functional contribution of the microbiota and associated metabolites as a source of mechanistic insight and targets for therapeutic modulation.

Inhibition of mite-induced dermatitis, pruritus, and nerve sprouting in mice by the endothelin receptor antagonist bosentan

BACKGROUND

Endothelin-1 (EDN1) can evoke histamine-independent pruritus in mammals and is upregulated in the lesional epidermis of atopic dermatitis (AD). EDN1 increases the production of interleukin 25 (IL-25) from keratinocytes to accelerate T helper type 2 immune deviation. Plasma EDN1 levels are positively correlated with the clinical severity and itch intensity of AD. Therefore, we hypothesized that the inhibition of EDN1 might be useful for treating atopic inflammation and itch and investigated the effects of the topical application of the EDN1 receptor antagonist bosentan on the skin inflammation and itch in a murine AD model.

METHODS

We analyzed the mite-induced AD-like NC/Nga murine model, which was topically applied with bosentan or ethanol control every day for 3 weeks. We also subjected in vitro primary sensory neuron culture systems to nerve elongation and branching assays after EDN1 stimulation.

RESULTS

Topical application of bosentan significantly attenuated the development of mite-induced AD-like skin inflammation, dermatitis scores, ear thickness, scratching bouts, and serum level of thymus and activation-regulated chemokine in NC/Nga mice. Bosentan application also significantly reduced the gene expression of Il13, Il17, and Ifng in the treated lesions. Histologically, the number of infiltrated dermal cells, the epidermal EDN1 expression, and the number of intraepidermal nerve fibers were significantly inhibited upon bosentan application. While EDN1 significantly elongated the neurites of dorsal root ganglion cells in a dose- and time-dependent manner, bosentan treatment attenuated this.

CONCLUSIONS

EDN1 plays a significant role in mite-induced inflammation and itch. Topical bosentan is a potential protective candidate for AD.

Atopic Dermatitis in Older Adults: A Review of Treatment Options

Atopic dermatitis (AD) in older adults (elderly AD) has recently emerged as a newly defined subgroup of AD. When selecting treatment options, clinical characteristics of elderly AD and age-specific factors of older patients must be considered. As in other age groups, regular application of moisturizers in combination with topical corticosteroids and calcineurin inhibitors, adjunctive administration of oral antihistamines/anti-allergic drugs, and avoidance of exacerbating factors comprise basic treatments for elderly AD. For moderate-to-severe cases and/or in those with a decreased ability to use topical treatments, powerful anti-inflammatory treatments may become necessary as additional treatment options. While low-dose oral corticosteroids may be useful for cases of elderly AD, careful attention should be paid to adverse effects. Oral cyclosporine (ciclosporin) is less commonly used due to the increased risk of malignancy and organ toxicity in older patients with AD. Narrow-band ultraviolet B phototherapy may also be useful for older patients, although the necessity of frequent hospital visits for irradiation therapy may become a burden of disease for such patients. As a biologic, dupilumab therapy markedly improves skin lesions and itch in older patients with AD, with a rapid response and non-serious adverse effects. Nevertheless, injection pain, expensive medical care, and regular follow-up every 2 weeks are disadvantages of dupilumab therapy. Therefore, clinicians must prioritize individualized treatment options that will reduce the burden of disease for cases of elderly AD.

The Pathogenesis of Fungal-Related Diseases and Allergies in the African Population: The State of the Evidence and Knowledge Gaps

The prevalence of allergic diseases in the African continent has received limited attention with the allergic diseases due to fungal allergens being among the least studied. This lead to the opinion being that the prevalence of allergic disease is low in Africa. Recent reports from different African countries indicate that this is not the case as allergic conditions are common and some; particularly those due to fungal allergens are increasing in prevalence. Thus, there is need to understand both the aetiology and pathogenies of these diseases, particularly the neglected fungal allergic diseases. This review addresses currently available knowledge of fungal-induced allergy, disease pathogenesis comparing findings from human versus experimental mouse studies of fungal allergy. The review discusses the potential role of the gut mycobiome and the extent to which this is relevant to fungal allergy, diagnosis and human health.

Identification of B Cell Epitopes of Blo t 13 Allergen and Cross-Reactivity with Human Adipocytes and Heart Fatty Acid Binding Proteins

Cross-reactivity between allergens and human proteins could have a clinical impact in allergic diseases. Blo t 13 is an allergen from the mite Blomia tropicalis, which belongs to the fatty acid binding protein (FABP) family and has structural homology with human FABPs. This work aimed to map B cell epitopes on Blo t 13 and to identify epitopes involved in cross-reactivity with human heart FABP (FABP3) and adipocyte FABP (FABP4). Sera from 25 patients with house dust mite (HDM) allergy that were sensitized to Blo t 13 were used for testing the reactivity of immunoglobulin E (IgE) and IgG to FABP. The epitope mapping of Blo t 13 was performed using overlapping peptides, and cross-reactivity between Blo t 13 and human FABP was analyzed using human sera and anti-Blo t 13 monoclonal antibodies. IgE antibodies to all FABPs were detected in 14/25 serum samples, and IgG was detected in 25/25 serum samples. The cross-reactivity of Blo t 13 was 42% with FABP3 and 48% with FABP4. Two IgE-binding regions were identified in Blo t 13; one between residues 54 and 72 (the main cross-reacting region) and another between residues 111 to 129. Our results suggest that exposure to the Blo t 13 allergen could induce an auto-reactive response to endogenous FABP in allergic patients sensitized to Blo t 13.

The role of Staphylococcus aureus in atopic dermatitis: microbiological and immunological implications

Introduction

Atopic dermatitis (AD) is an inflammatory disease characterised by chronic and recurrent course. Its predominant symptom is skin pruritus. Therefore, many AD patients have recurrent skin infections and are susceptible to the colonisation of apparently healthy skin and nasal vestibule by Staphylococcus aureus (S. aureus). Some S. aureus strains are capable of producing exotoxins.

Aim

To assess the relation between the total IgE (tIgE) and asIgE targeted against SEA (SEA-sIgE) and SEB (SEB-sIgE), as indicators of the severity of the course of AD, and the presence of S. aureus on apparently healthy skin, in skin lesions and in the nasal vestibule.

Material and methods

The research was performed in a population of 134 AD patients (61 men and 73 women) aged 2–86 years. Three smears were collected for microbiological investigations: from the nasal vestibule, from the skin where lesions appeared at the moment of investigations and from the skin which was free from the eczema. On collection the material was cultured on solid and broth mediums. After incubation each medium was thoroughly analysed for the presence of S. aureus.

Results

There was a statistically significant correlation between healthy skin colonisation by S. aureus and increased SEA-sIgE. The same correlation was proved between healthy skin colonisation by S. aureus and increased SEB-sIgE. There was a statistically significant correlation between colonisation of the nasal vestibule by S. aureus and the SEA-sIgE and SEB-sIgE serum concentration.

Conclusions

It seems that the colonisation of the lesioned skin, healthy skin and the anterior nares by S. aureus is related with higher tIgE serum concentration, which translates to more severe course of the disease. Significantly increased SEA-IgE and SEB-IgE concentrations were observed in the patients whose tIgE serum concentration was statistically higher.

The antimicrobial protein S100A12 identified as a potential autoantigen in a subgroup of atopic dermatitis patients

Background

Atopic dermatitis (AD) is a complex heterogeneous chronic inflammatory skin disease. Specific IgE antibodies against autoantigens have been observed in a subgroup of AD patients, however, little is known about IgG-auto-reactivity in AD. To investigate the presence of autoreactive IgG antibodies, we performed autoantibody profiling of IgG in patients with AD of different severities and in healthy controls (HC).

Methods

First, we performed an untargeted screening in plasma samples from 40 severe AD (sAD) patients and 40 HC towards 1152 protein fragments on planar antigen microarrays. Next, based on the findings and addition of more fragments, a targeted antigen suspension bead array was designed to profile a cohort of 50 sAD patients, 123 patients with moderate AD (mAD), and 84 HC against 148 protein fragments representing 96 unique proteins.

Results

Forty-nine percent of the AD patients showed increased IgG-reactivity to any of the four antigens representing keratin associated protein 17-1 (KRTAP17-1), heat shock protein family A (Hsp70) member 4 (HSPA4), S100 calcium binding proteins A12 (S100A12), and Z (S100Z). The reactivity was more frequent in the sAD patients (66%) than in those with mAD (41%), whereas only present in 25% of the HC. IgG-reactivity to S100A12, a protein including an antimicrobial peptide, was only observed in AD patients (13/173).

Conclusions

Autoantibody profiling of IgG-reactivity using microarray technology revealed an autoantibody-based subgroup in patients with AD. The four identified autoantigens and especially S100A12 could, if characterized further, increase the understanding of different pathogenic mechanisms behind AD and thereby enable better treatment.

Electronic supplementary material

The online version of this article (10.1186/s13601-019-0240-4) contains supplementary material, which is available to authorized users.

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.

The Role of Proteasome Inhibitor MG132 in 2,4-Dinitrofluorobenzene-Induced Atopic Dermatitis in NC/Nga Mice

BACKGROUND

Although immunosuppressants for therapy of atopic dermatitis (AD) are still being sought, proteasome inhibitors are also potential candidates for the treatment of AD. Proteasome inhibitors exert various effects by blocking proteasomal degradation and help regulate processes such as apoptosis induction via caspase-9, cell cycle progression via cyclins, NF-κB inactivation via IκB, and downregulation of antigen cross-presentation. The cells targeted by proteasome inhibitors are therefore activated cells undergoing proliferation or differentiation, and antigen-presenting cells carrying out protein degradation.

OBJECTIVES

This study investigated the therapeutic effects and side effects of a proteasome inhibitor, MG132, on the treatment of AD.

METHODS

AD-like disease in NC/Nga mice housed under specific pathogen-free conditions was induced by repeated application of 2,4-dinitrofluorobenzene (DNFB). Disease progression was evaluated by inflammation score, histopathology, and serum IgE level, and the effects of systemic MG132 administration were investigated. The percentages and absolute numbers for each population of Th1, Th2, and Th17 cells in the axillary lymph nodes were analyzed by flow cytometry.

RESULTS

DNFB application increased the expression of a unique major histocompatibility complex class I mutant molecule D/Ldm7 in dendritic cells (DCs), and increased Th1 and Th17 cells in NC/Nga mice. In vivo MG132 administration to NC/Nga mice with DNFB-induced dermatitis reduced Th17 cells but maintained the level of Th1 cells, resulting in the alleviation of dermatitis lesions by decreasing both serum IgE hyperproduction and mast cell migration. To understand the mechanisms maintaining Th1 cell levels following in vivo MG132-administration, we focused on the role of proteasomes regulating D/Ldm7 expression. Interestingly, 20S proteasome activity was higher in NC/Nga DCs than in BALB/c DCs. In vitro MG132 administration partially increased D/Ldm7 expression in a dose-dependent manner during DC maturation, and induced IFN-γ production from autoreactive CD8+ T cells but not from CD4+ T cells following coculturing with D/Ldm7-upregulated DCs.

CONCLUSION

Although MG132 administration temporarily alleviated AD pathogenesis in NC/Nga mice, prolonged MG132 treatment may result in immunopathogenesis leading to chronic AD due to its side effect of maintaining Th1 levels via autoreactive CD8+ T cells.

Immunoglobulin E-Mediated Autoimmunity

The study of autoimmunity mediated by immunoglobulin E (IgE) autoantibodies, which may be termed autoallergy, is in its infancy. It is now recognized that systemic lupus erythematosus, bullous pemphigoid (BP), and chronic urticaria, both spontaneous and inducible, are most likely to be mediated, at least in part, by IgE autoantibodies. The situation in other conditions, such as autoimmune uveitis, rheumatoid arthritis, hyperthyroid Graves’ disease, autoimmune pancreatitis, and even asthma, is far less clear but evidence for autoallergy is accumulating. To be certain of an autoallergic mechanism, it is necessary to identify both IgE autoantibodies and their targets as has been done with the transmembrane protein BP180 and the intracellular protein BP230 in BP and IL-24 in chronic spontaneous urticaria. Also, IgE-targeted therapies, such as anti-IgE, must have been shown to be of benefit to patients as has been done with both of these conditions. This comprehensive review of the literature on IgE-mediated autoallergy focuses on three related questions. What do we know about the prevalence of IgE autoantibodies and their targets in different diseases? What do we know about the relevance of IgE autoantibodies in different diseases? What do we know about the cellular and molecular effects of IgE autoantibodies? In addition to providing answers to these questions, based on a broad review of the literature, we outline the current gaps of knowledge in our understanding of IgE autoantibodies and describe approaches to address them.

Targeting IgE Antibodies by Immunoadsorption in Atopic Dermatitis

One major hallmark of atopic dermatitis (AD) is the elevated level of total serum IgE, which has been reported to be partly of the autoreactive type in a subset of patients. Immunoadsorption (IA) has been successfully applied in various classical autoantibody-mediated diseases such as pemphigus. Recent reports proposed the use of IA also for patients with severe AD and high total serum IgE levels. In this mini-review, we summarize the current knowledge about this novel treatment approach for AD and briefly discuss the so far incompletely known role of autoreactive IgE as potential target of IA therapy in this common inflammatory skin disorder.

Signs of atopic dermatitis and contact dermatitis affected by distinct H2-haplotype in the NC/Nga genetic background

We recently advocated in favour of naming a novel H2-haplotype consisting of K^d, D/L^dm7, I-A^k and I-E^k in the atopic dermatitis (AD) mouse model NC/Nga as “H-2^nc.” The role of the H2-haplotype in AD development was investigated in H2^b-congenic NC/Nga mice (NC.h2^b/b and NC.h2^b/nc) established by backcrossing. A severe 2,4-dinitrofluorobenzene (DNFB)-induced dermatitis in NC/Nga was alleviated partially in NC.h2^b/nc and significantly in NC.h2^b/b. The AD phenotype was correlated with thymic stromal lymphopoietin (TSLP)-epidermal expression levels and serum levels of total IgE and IL-18/IL-33. Histologically, allergic contact dermatitis (ACD) was accompanied by lymphocytes and plasma cells-infiltrating perivasculitis in NC.h2^b/nc and NC.h2^b/b and clearly differed from AD accompanied by neutrophils, eosinophils and macrophages-infiltrating diffuse suppurative dermatitis in NC/Nga. Interestingly, IFN-γ/IL-17 production from autoreactive CD4⁺ T-cells remarkably increased in DNFB-sensitised NC.h2^b/b but not in NC/Nga. Our findings suggest that AD or ACD may depend on haplotype H-2^nc or H-2^b, respectively, in addition to the NC/Nga genetic background.

IgE autoantibodies and their association with the disease activity and phenotype in bullous pemphigoid: a systematic review

Bullous pemphigoid (BP) is the most common autoimmune skin disease of blistering character. The underlying pathophysiological mechanism involves an immune attack, usually by IgG class autoantibodies, on the autoantigen BP 180/BPAg2, which is a type XVII collagen (COL17) protein acting as the adhesion molecule between the epidermis and the basement membrane of the dermis. About 40 years ago, following consistent findings of elevated total serum IgE levels in BP patients, it was hypothesized that IgE may be involved in the pathophysiology of BP. Our objective was to determine whether there is strong evidence for an association between IgE class autoantibodies and the clinical severity or phenotype of BP. Three databases were searched for relevant studies and appropriate exclusion and inclusion criteria were applied. Data was extracted and assessed in relation to the study questions concerning the clinical significance of IgE autoantibodies in BP. Nine studies found that anti-BP180 autoantibodies of IgE class are associated with increased severity of BP, whereas two studies did not find such an association. The number of studies which found an association between higher IgE autoantibody levels and the erythematous urticarial phenotype of BP (5) was equal in number to the studies which found no such association (5). In conclusion, higher serum IgE autoantibody levels are associated with more severe clinical manifestations of BP. There is insufficient evidence to support higher IgE autoantibody levels being associated with specific clinical phenotypes of BP.

Novel concepts of prevention and treatment of atopic dermatitis through barrier and immune manipulations with implications for the atopic march

Skin barrier abnormalities have been suggested to play an essential role in initiation of early atopic dermatitis (AD). Antigen penetration through a compromised barrier likely leads to increased innate immune responses, antigen-presenting cell stimulation, and priming of overt cutaneous disease. In a T_H2-promoting environment, T-cell/B-cell interactions occurring in regional lymph nodes lead to excessive IgE switch. Concurrent redistribution of memory T cells into the circulation not only leads to exacerbation of AD through T-cell skin infiltration but also spreads beyond the skin to initiate the atopic march, which includes food allergy, asthma, and allergic rhinitis. Possible primary interventions to prevent AD are focusing on improving skin barrier integrity, including supplementing barrier function with moisturizers. As for secondary prophylaxis in children with established AD, this can be stratified into prevention of disease exacerbations by using proactive approaches (with either topical corticosteroids or topical calcineurin inhibitors) in mild AD cases or the prevention of other atopic disorders that will probably mandate systemic immunosuppression in severe AD cases.

[Neurodermatitis : Atopy of the skin]

Atopic dermatitis is one of the most common skin diseases and is associated with an impaired quality of life due to tormenting itching and stigmatization. The disease almost always manifests in early childhood and exhibits specific features in this phase, with involvement of the extensor sides of the extremities. During the further course of disease, the typical flexor involvement becomes quite clear and a considerable proportion of patients develop the associated atopic respiratory diseases. Therapeutic and prophylactic measures focus on the prevention of trigger factors, basic skin care, and application of lipid-replenishing creams, as well as patient and parent education. In the case of exacerbation, anti-inflammatory drugs are treatment of choice.

Humoral and Cellular Autoreactivity to Epidermal Proteins in Atopic Dermatitis

Atopic dermatitis (AD), a chronic relapsing inflammatory disease of the skin, is an important public health concern affecting 10-20 % of children worldwide. The etiology and pathogenesis of AD involve the interplay of genetic and environmental factors, including abnormalities in skin integrity and a skewed immune system usually driven by a Th2 phenotype in childhood with a switch to Th1 in the chronic phase of disease. Children and adults with AD commonly have elevated IgE levels directed to multiple different antigens, including aeroallergens, food allergens, and microbial proteins. IgE targeting self-antigens from epidermal proteins have been detected in up to 91 % of patients, particularly in severe persistent AD. It has been suggested that the occurrence of autoreactivity develops in early childhood. However, it is not clear yet if autoreactive IgEs in patients with AD are pathogenic or just an epiphenomenon. The fact that these autoantibodies are associated with severity and are not present in other allergic or skin diseases favors the pathogenicity of IgE-mediated autoreactivity in AD. In this review, we evaluate the pathogenesis of AD and the emerging role of autoreactivity to various keratinocyte antigens involving both the humoral and cellular components of the immune system.

Role of IgE in autoimmunity

There is accumulating evidence to suggest that IgE plays a significant role in autoimmunity. The presence of circulating self-reactive IgE in patients with autoimmune disorders has been long known but, at the same time, largely understudied. However, studies have shown that the increased IgE concentration is not associated with higher prevalence for atopy and allergy in patients with autoimmune diseases, such as systemic lupus erythematosus. IgE-mediated mechanisms are conventionally known to facilitate degranulation of mast cells and basophils and promote TH2 immunity, mechanisms that are not only central to mounting an appropriate defense against parasitic worms, noxious substances, toxins, venoms, and environmental irritants but that also trigger exuberant allergic reactions in patients with allergies. More recently, IgE autoantibodies have been recognized to participate in the self-inflicted damaging immune responses that characterize autoimmunity. Such autoimmune responses include direct damage on tissue-containing autoantigens, activation and migration of basophils to lymph nodes, and, as observed most recently, induction of type 1 interferon responses from plasmacytoid dendritic cells. The importance of IgE as a central pathogenic mechanism in autoimmunity has now been clinically validated by the approval of omalizumab, an anti-IgE mAb, for patients with chronic spontaneous urticaria and for the clinical benefit of patients with bullous pemphigoid. In this review we summarize recent reports describing the prevalence of self-reactive IgE and discuss novel findings that incriminate IgE as central in the pathogenesis of inflammatory autoimmune disorders.

The adaptive immune system in atopic dermatitis and implications on therapy

In atopic dermatitis (AD), the skin inflammation is believed to occur due to a misdirected immune reaction against harmless antigens on the one hand, and to a disturbed skin barrier on the other. In recent years, vast efforts have been made to investigate the relevance and details of the immune response to allergens. Clinically, it was demonstrated for the first time that aeroallergen exposure leads to worsening of AD symptoms. An overexpression of Th2 cytokines has been observed in acute and subacute lesions of AD. The clinical impact of the key Th2 cytokines IL-4 and IL-13 on atopic dermatitis has recently been shown in clinical studies with dupilumab, a monoclonal antibody which blocks the IL-4/IL-13 receptor. In vitro data indicate, however, that the T cell response is not solely Th2-polarized but may lead to heterogeneous cytokine production involving IFN-γ and IL-17 in an allergen-dependent manner. Classical thymus-derived Foxp3 T cells have interestingly been detected in elevated numbers in the circulation of AD patients. Therapeutic approaches with allergen specific immunotherapy aim to induce regulatory T cells of the Tr1 type. The strikingly altered microbiome of AD skin with diminished diversity of bacteria on lesional skin but increases of S. aureus colonization and the sensitization against microbial allergens and homologue self-proteins deserve special attention. For the treatment of itch symptoms, which still represent a challenge in daily practice, promising data have been published on the relevance of the H(histamine)4-receptor and on mediators such as IL-31, TSLP.