Tissue eosinophilia in acute and chronic atopic dermatitis: a morphometric approach using quantitative image analysis of immunostaining

Atopic Dermatitis Itch: Scratching for an Explanation

Chronic pruritus is a cardinal symptom of atopic dermatitis (AD). The mechanisms underlying atopic itch involve intricate crosstalk among skin, immune components, and neural components. In this review, we explore these mechanisms, focusing on key players and interactions that induce and exacerbate itch. We discuss the similarities and differences between pruritus and pain in patients with AD as well as the relationship between pruritus and factors such as sweat and the skin microbiome. Furthermore, we explore novel targets that could provide significant itch relief in these patients as well as exciting future research directions to better understand atopic pruritus in darker skin types.

Considerations for managing elderly patients with atopic dermatitis

INTRODUCTION

Atopic dermatitis (AD) diagnosis in elderly is challenging, due to its clinical polymorphism and the lack of diagnostic biomarkers. Moreover, the chronicity of the disease and the complex pathogenetic mechanism, make elderly AD management challenging.

AREAS COVERED

A narrative review of the current literature was performed using the PubMed, Medline, Embase, and Cochrane Skin databases, by researching the following terms: 'atopic dermatitis,' 'clinical phenotypes,' 'eczema,' 'elderly patients,' 'elderly type atopic dermatitis,' 'eczema clinical presentation.' The aim was to report the current knowledge on pathogenesis, clinical presentation, and treatment options of elderly AD.

EXPERT OPINION

Elderly type AD has recently been identified as a separate entity, with an increasing prevalence. With aging, both immunosenescence and barrier alterations can cause or modify AD presentation. Moreover, a chronic proinflammatory state (so-called 'inflammaging') is often present in elderly subjects. Older patients with AD may present with peculiar immunophenotypic profile, making AD diagnosis challenging. Similarly, the chronicity of the disease and the complex pathogenetic mechanism, make AD management a challenge. Indeed, systemic therapies for AD are often contraindicated or not tolerated and the management of elderly type AD is often burdened with numerous difficulties, leading to undertreated disease. Even if dupilumab and tralokinumab represent a valuable therapeutic weapon, more data on safety of JAK inhibitors are required.

Biologic and small-molecule therapy for treating moderate to severe atopic dermatitis: Mechanistic considerations

Atopic dermatitis (AD) is a complex and heterogeneous skin disease for which achieving complete clinical clearance for most patients has proven challenging through single cytokine inhibition. Current studies integrate biomarkers and evaluate their role in AD, aiming to advance our understanding of the diverse molecular profiles implicated. Although traditionally characterized as a TH2-driven disease, extensive research has recently revealed the involvement of TH1, TH17, and TH22 immune pathways as well as the interplay of pivotal immune molecules, such as OX40, OX40 ligand (OX40L), thymic stromal lymphopoietin, and IL-33. This review explores the mechanistic effects of treatments for AD, focusing on mAbs and Janus kinase inhibitors. It describes how these treatments modulate immune pathways and examines their impact on key inflammatory and barrier biomarkers.

Staphylococcus aureus proteases trigger eosinophil-mediated skin inflammation

Staphylococcus aureus skin colonization and eosinophil infiltration are associated with many inflammatory skin disorders, including atopic dermatitis, bullous pemphigoid, Netherton's syndrome, and prurigo nodularis. However, whether there is a relationship between S. aureus and eosinophils and how this interaction influences skin inflammation is largely undefined. We show in a preclinical mouse model that S. aureus epicutaneous exposure induced eosinophil-recruiting chemokines and eosinophil infiltration into the skin. Remarkably, we found that eosinophils had a comparable contribution to the skin inflammation as T cells, in a manner dependent on eosinophil-derived IL-17A and IL-17F production. Importantly, IL-36R signaling induced CCL7-mediated eosinophil recruitment to the inflamed skin. Last, S. aureus proteases induced IL-36α expression in keratinocytes, which promoted infiltration of IL-17-producing eosinophils. Collectively, we uncovered a mechanism for S. aureus proteases to trigger eosinophil-mediated skin inflammation, which has implications in the pathogenesis of inflammatory skin diseases.

Clinical Features of Paediatric Inflammatory Epidermolysis Bullosa Acquisita: A Case Series Study

Epidermolysis bullosa acquisita (EBA) rarely develops in childhood. This study retrospectively recruited paediatric patients with EBA (age ≤ 16 years), diagnosed by clinical and histopathological features and results of immunofluorescence, immunoblotting and enzyme-linked immunosorbent assay (ELISA), and reviews their clinical manifestations, histopathology, immunological features, and responses to various treatments. All 7 included patients presented with inflammatory EBA. Among them, 3 had a bullous pemphigoid-like phenotype. Pathologically, in addition to dermal-epidermal blistering, in all patients, the distribution of neutrophils was superficial perivascular or interstitial, or in the dermal papilla. Mixed neutrophils and eosinophils were detected in 2 of the 3 patients with bullous pemphigoid-like phenotypes. In addition to treatment with glucocorticoids, dapsone was administered in 4 patients, while thalidomide and sulfasalazine were administered in 1 patient. All patients responded to the these therapies. Relapse was mainly due to reduction and cessation of glucocorticoids. In conclusion, EBA in childhood may be unique, and thus distinct from its adult counterpart. Specific treatment and follow-up protocols are required for therapy of this rare autoimmune skin disease in children.

Cutaneous basophil infiltration in atopic dermatitis is associated with abundant epidermal infiltration of helper T cells: A preliminary retrospective study

Atopic dermatitis (AD) is a heterogenous inflammatory skin disorder. Our previous study revealed that basophil infiltration in skin is observed in approximately 60% of AD cases. However, the clinical and histological characteristics of AD associated with basophil infiltration remain unclear. We examined basophil infiltration by immunohistochemical staining of 38 specimens from 34 patients who underwent skin biopsies to diagnose AD from April 2016 to September 2021 at Tokyo Medical and Dental University Hospital. The patients/specimens were divided into two groups, 17 patients/21 specimens associated with little or no basophil infiltration (basophil-low group) and 17 patients/17 specimens associated with marked basophil infiltration (basophil-high group). The clinical characteristics of the patients (age, sex, complications, blood biomarkers, skin symptoms, and treatment) and histological features of the specimens were compared between the groups. Basophil-high patients were significantly younger than basophil-low patients. Blood basophil counts were higher in basophil-high patients than in basophil-low patients. CD4+ T-cell infiltration was more marked in basophil-high specimens than in basophil-low specimens. CD4+ T cells infiltrated into the dermis as well as into the epidermis only in the basophil-high specimens. Thus, basophil-high AD can be characterized by skin lesions associated with abundant helper T-cell infiltration in younger patients.

The role of eosinophils in the differential diagnosis of inflammatory skin diseases

Eosinophils are known to be present in inflammatory skin diseases, but their diagnostic utility is not well established. Upon review of the published status of lesional eosinophils, several categories were identified. 1) Lesional eosinophils highly characteristic such that, in their absence, the pathologist may question the diagnosis. These include arthropod bite reactions and scabies, urticarial dermatitis, and other eosinophilic dermatoses. 2) Lesional eosinophils rare or absent, such that, in their presence, the pathologist may question the diagnosis. These include pityriasis lichenoides, graft versus host disease, and connective tissue disorders. 3) Lesional eosinophils variable and, while in some cases expected, are not required for diagnosis. These include drug reactions, atopic dermatitis and allergic contact dermatitis. 4) Lesional eosinophils variable and not expected but may be seen to a limited extent. These include lichen planus and psoriasis.

Association of Inflammatory Indicators and Clinical Signs and Itch in Atopic Dermatitis Patients Treated with Simiao Pill Combined with Halomethasone Cream

Background

Atopic dermatitis (AD) is a chronic inflammatory skin disease characterized by symptoms such as itchiness, scaling, and erythema. Previous studies have suggested that inflammatory indicators obtained from peripheral blood cell count can serve as markers for atopic dermatitis pruritus and severity. The objective of this study was to investigate whether these indicators are associated with treatment efficacy in AD patients who received a combination of halomethasone cream and Simiao pill (SMP).

Methods

131 adult patients diagnosed with AD between January 2020 to August 2022 and treated with topical halometasone ointment combined with oral Simiao pill for a month were recruited and clinical dates of patients were collected. Inflammatory indicators included Eosinophil-to-lymphocyte ratio (ELR), neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR), platelet-to-lymphocyte ratio (PLR), serum leukotriene B4 (LTB4), and thymic stromal lymphopoietin (TSLP) and clinical indexes for assessing eczema area and severity index (EASI) and peak pruritus-numerical rating scale (PP-NRS). Relationship of baseline and changes of these Inflammatory indicators and that of clinical indexes were analyzed.

Results

ELR, NLR, LTB4, and TSLP levels have positive association with EASI before treatment, and baseline ELR and LTB4 levels have positive relationship with PP-NRS. ELR, NLR, LTB4, and TSLP showed a significant decrease at week 2 and the low levels were maintained until week 8 after treatment, while no significant changes were observed in levels of MLR and PLR. There was a significant correlation between the decrease of ELR and the decreases of EASI and PP-NRS at weeks 2, 4 and 8 of the treatment.

Conclusion

ELR may serve as an effective and convenient indicator in assessing the disease severity and efficacy of SMP therapy for AD.

Lupeol alleviates atopic dermatitis-like skin inflammation in 2,4-dinitrochlorobenzene/Dermatophagoides farinae extract-induced mice

BACKGROUND

Atopic dermatitis (AD) is a chronic inflammatory skin disease that affects from children to adults widely, presenting symptoms such as pruritus, erythema, scaling, and dryness. Lupeol, a pentacyclic triterpenoid, has anti-inflammatory and antimicrobial activities. Based on these properties, the therapeutic effects of lupeol on skin disorders have been actively studied. In the present study, we aimed to determine the effectiveness of lupeol on AD.

METHODS

We utilized tumor necrosis factor (TNF)-α/interferon (IFN)-γ-stimulated keratinocytes and 2, 4-dinitrochlorobenzene/Dermatophagoides farinae extract (DFE)-induced AD mice to confirm the action.

RESULTS

Lupeol inhibited TNF-α/IFN-γ-stimulated keratinocytes activation by reducing the expressions of pro-inflammatory cytokines and chemokines which are mediated by the activation of signaling molecules such as signal transducer and activator of transcription 1, mitogen-activated protein kinases (p38 and ERK), and nuclear factor-κB. Oral administration of lupeol suppressed epidermal and dermal thickening and immune cell infiltration in ear tissue. Immunoglobulin (Ig) E (total and DFE-specific) and IgG2a levels in serum were also reduced by lupeol. The gene expression and protein secretion of T helper (Th) 2 cytokines, Th1 cytokines, and pro-inflammatory cytokine in ear tissue were decreased by lupeol.

CONCLUSIONS

These results suggest that lupeol has inhibitory effects on AD-related responses. Therefore, lupeol could be a promising therapeutic agent for AD.

The translational revolution in atopic dermatitis: the paradigm shift from pathogenesis to treatment

Atopic dermatitis (AD) is the most common inflammatory skin disease, and it is considered a complex and heterogeneous condition. Different phenotypes of AD, defined according to the patient age at onset, race, and ethnic background; disease duration; and other disease characteristics, have been recently described, underlying the need for a personalized treatment approach. Recent advancements in understanding AD pathogenesis resulted in a real translational revolution and led to the exponential expansion of the therapeutic pipeline. The study of biomarkers in clinical studies of emerging treatments is helping clarify the role of each cytokine and immune pathway in AD and will allow addressing the unique immune fingerprints of each AD subset. Personalized medicine will be the ultimate goal of this targeted translational research. In this review, we discuss the changes in the concepts of both the pathogenesis of and treatment approach to AD, highlight the scientific rationale behind each targeted treatment and report the most recent clinical efficacy data.

Topical Skullcapflavone II attenuates atopic dermatitis in a mouse model by directly inhibiting associated cytokines in different cell types

Skullcapflavone II (SFII), a flavonoid derived from Scutellaria baicalensis, is an anticancer agent. We aimed to validate SFII for atopic dermatitis (AD) therapy by demonstrating the anti-inflammatory effects of SFII in an AD mouse model produced by the topical application of the vitamin D3 analog MC903. We showed that topical treatment with SFII significantly suppressed MC903-induced serum IgE levels compared with topical hydrocortisone (HC) treatment. Topical SFII also prevents MC903-induced pruritus, skin hyperplasia, and inflammatory immune cell infiltration into lesional skin comparable to topical HC. In addition, MC903-induced immune cell chemoattractants and AD-associated cytokine production in skin lesions were effectively suppressed by topical SFII. The production of MC903-induced effector cytokines influencing T helper (Th)2 and Th17 polarization in lesioned skin is significantly inhibited by topical SFII. Furthermore, we showed that SFII can directly inhibit the production of AD-associated cytokines by human primary keratinocytes, mouse bone marrow-derived cells (BMDCs), and mouse CD4⁺ T cells in vitro. Lastly, we demonstrated that topical SFII more effectively suppressed serum IgE levels, the production of IL-4 and thymic stromal lymphopoietin (TSLP), and infiltration of CD4⁺ T cells and Gr-1⁺ cells (neutrophils) into lesion skin compared to topical baicalein (a flavonoid derived from Scutellaria baicalensis), which has anti-inflammatory effects. Taken together, our findings suggest that SFII may have promising therapeutic potential for this complex disease via the regulation of multiple AD-associated targets.

Therapeutic Potential of MRGPRX2 Inhibitors on Mast Cells

Mast cells (MCs) act as primary effectors in inflammatory and allergic reactions by releasing intracellularly-stored inflammatory mediators in diseases. The two major pathways for MC activation are known to be immunoglobulin E (IgE)-dependent and -independent. Although IgE-dependent signaling is the main pathway to MC activation, IgE-independent pathways have also been found to serve pivotal roles in the pathophysiology of various inflammatory conditions. Recent studies have shown that human and mouse MCs express several regulatory receptors such as toll-like receptors (TLRs), CD48, C300a, and GPCRs, including mas-related GPCR-X2 (MRGPRX2). MRGPRX2 has been reported as a novel GPCR that is expressed in MCs activated by basic secretagogues, neurokinin peptides, host defense antimicrobial peptides, and small molecule compounds (e.g., neuromuscular blocking agents) and leads to MC degranulation and eicosanoids release under in vitro experimental condition. Functional analyses of MRGPRX2 and Mrgprb2 (mouse ortholog) indicate that MRGPRX2 is involved in MC hypersensitivity reactions causing neuroinflammation such as postoperative pain, type 2 inflammation, non-histaminergic itch, and drug-induced anaphylactic-like reactions. In this review, we discuss the roles in innate immunity through functional studies on MRGPRX2-mediated IgE-independent MC activation and also the therapeutic potential of MRGPRX2 inhibitors on allergic and inflammatory diseases.

Type 2 immunity-driven diseases: Towards a multidisciplinary approach

Asthma, atopic dermatitis and chronic rhinoconjunctivitis are highly heterogeneous. However, epidemiologic associations exist between phenotypic groups of patients. Atopic march is one such association but is not the only common point. Indeed, beyond such phenotypes, hallmarks of type 2 immunity have been found in these diseases involving immune dysregulation as well as environmental triggers and epithelial dysfunction. From the canonical Th2 cytokines (IL-4, IL-5, IL-13), new cellular and molecular actors arise, from the epithelium's alarmins to new innate immune cells. Their interactions are now better understood across the different environmental barriers, and slight differences appeared. In parallel, the development of type 2-targeting biotherapies not only raised hope to treat those diseases but also raised new questions regarding their true pathophysiological involvement. Here, we review the place of type 2 immunity in the different phenotypes of asthma, chronic rhinitis, chronic rhinosinusitis and atopic dermatitis, highlighting nuances between them. New hypotheses rising from the use of biotherapies will be discussed along with the uncertainties and unmet needs of this field.

Beneficial effects of ROCEN (Topical Nano-arthrocen) on atopic dermatitis in mice

Objective

Atopic dermatitis (AD) is a chronic inflammatory skin disease mainly caused by immune stimuli. The current study was conducted to investigate the effects of ROCEN and to compare it with betamethasone (Beta) on mice subjected to AD.

Methods

First, the safety of topical ROCEN was tested to determine possible sensitization induction in vivo. Then, the mice were subjected to oxazolone (Oxa) to induce chronic AD. Consequently, they underwent treatment with ROCEN and Beta. Scratching and wiping behaviors related to dermatitis were evaluated in treated animals for 35 days. The histopathology and immunohistochemistry (IHC) analysis of interleukin-8 (IL-8) and tumor necrosis factor-α (TNF-α) cytokines were performed on the dorsal skin of the treated mice.

Results

Topical administration of ROCEN and Beta to the dorsum of sensitized mice for 5 weeks significantly alleviated scratching and wiping symptoms and reduced erythema, scaling, and edema in the skin of the mice with AD. Moreover, histological indices showed that ROCEN effectively reduced leucocyte infiltration and improved skin healing parameters in treated AD mice. Application of ROCEN or Beta reduced IHC markers including IL-8 and TNF-α significantly.

Conclusion

ROCEN alleviated the AD symptoms similar to betamethasone in an experimental animal model.

Novel Targeted Biological Agents for the Treatment of Atopic Dermatitis

Atopic dermatitis (AD) is a common inflammatory dermatologic disease clinically characterized by intense itch, recurrent eczematous lesions, and a chronic or relapsing disease course. Mild-to-moderate AD can be controlled by using moisturizers and topical immunomodulators such as topical corticosteroids and calcineurin inhibitors. If topical therapies fail, phototherapy and systemic immunosuppressant therapies, such as ciclosporin, methotrexate, and azathioprine, can be considered. However, relapse and side effects could still occur. The pathogenesis of AD involves epidermal barrier dysfunction, skin microbiome abnormalities, and cutaneous inflammation. Inflammatory mediators, such as interleukin (IL)-4, IL-13, IL-31, IL-33, IL-17, IL-23, and thymic stromal lymphopoietin, are involved in AD development. Therefore, a series of biological agents targeting these cytokines are promising approaches for treating AD. Dupilumab is the first biological agent approved for the treatment of AD in patients aged 6 years and older in the United States. Tralokinumab, lebrikizumab, and nemolizumab have also been confirmed to have significant efficacy against AD in phase III or IIb clinical trials. Also, fezakinumab was effective in severe AD patients in a phase IIa trial. However, phase II trials of ustekinumab, tezepelumab, etokimab, secukinumab, and omalizumab have failed to meet their primary endpoints. Phase II trials of GBR 830 and KHK 4083 are ongoing. In general, further studies are needed to explore new therapeutic targets and improve the efficacy of biological agents.

Eosinophils in skin diseases

Eosinophil infiltration is a common finding in a broad spectrum of skin diseases, despite the fact that the skin is devoid of eosinophils under physiologic conditions. Although cutaneous eosinophilia is reactive, cytokine-mediated in most cases, diseases with an intrinsic mutation-mediated clonal expansion of eosinophils can also manifest on the skin. As eosinophils are involved in host defense, regulate immune responses, generate pruritus, induce remodeling and fibrosis, and can cause tissue damage, they have the capacity to actively contribute to the pathogenesis of diseases. Recent research provided deeper insights in the mechanisms, e.g., bacterial and viral clearance, blister formation, recruitment of cytotoxic T cells, and generation of pruritus, by which eosinophils might come into action. This review aims at providing an overview on the clinical presentations of eosinophil-associated dermatoses and the current understanding of their pathogenic role in these diseases. Further, we discuss the effects of therapies targeting eosinophils.

Immunological Aspects of Skin Aging in Atopic Dermatitis

The cutaneous immune response is important for the regulation of skin aging well as for the development of immune-mediated skin diseases. Aging of the human skin undergoes immunosenescence with immunological alterations and can be affected by environmental stressors and internal factors, thus leading to various epidermal barrier abnormalities. The dysfunctional epidermal barrier, immune dysregulation, and skin dysbiosis in the advanced age, together with the genetic factors, facilitate the late onset of atopic dermatitis (AD) in the elderly, whose cases have recently been on the rise. Controversial to the healthy aged skin, where overproduction of many cytokines is found, the levels of Th2/Th22 related cytokines inversely correlated with age in the skin of older AD patients. As opposed to an endogenously aged skin, the expression of the terminal differentiation markers significantly increases with age in AD. Despite the atenuated barrier disturbances in older AD patients, the aged skin carries an impairment associated with the aging process, which reflects the persistence of AD. The chronicity of AD in older patients might not directly affect skin aging but does not allow spontaneous remission. Thus, adult- and elderly subtypes of AD are considered as a lifelong disease.

Effect of Dupilumab on Laboratory Parameters in Adolescents with Atopic Dermatitis: Results from a Randomized, Placebo-Controlled, Phase 3 Clinical Trial

Background

Laboratory testing is typically required for patients with atopic dermatitis (AD) treated with systemic immunosuppressants. A previous analysis of laboratory outcomes in randomized, double-blinded, placebo-controlled clinical trials of dupilumab in adults with moderate-to-severe AD found no clinically important changes in hematologic, serum chemistry, and urinalysis parameters, supporting the use of dupilumab without routine laboratory monitoring.

Objective

The aim was to assess laboratory results in adolescents with moderate-to-severe AD treated with dupilumab in a phase 3, randomized, double-blind, placebo-controlled trial.

Methods

Adolescents aged ≥ 12 to < 18 years with moderate-to-severe AD were randomized 1:1:1 to subcutaneous dupilumab 200/300 mg every 2 weeks (q2w) (200 mg for patients < 60 kg at baseline; 300 mg for patients ≥ 60 kg at baseline); dupilumab 300 mg every 4 weeks (q4w); or placebo for 16 weeks. Laboratory evaluations included hematology, serum chemistry, and urinalysis parameters.

Results

Of 251 patients enrolled in the study, 250 received treatment and were included in the analysis. 4.7%, 2.4%, and 4.8% of patients receiving placebo, dupilumab 200/300 mg q2w, and dupilumab 300 mg q4w, respectively, had laboratory abnormalities reported as treatment-emergent adverse events, none of which prompted discontinuation of study treatment or study withdrawal. Mean eosinophil counts were elevated at baseline in all treatment groups. Patients in both dupilumab regimens, but not the placebo group, showed mild transient increases in mean eosinophil counts above baseline that returned to near-baseline values by week 16. Mean levels of lactate dehydrogenase trended towards the upper limit of normal at baseline and decreased with treatment; greater decreases were seen in dupilumab-treated patients than placebo-treated patients. There were no meaningful changes in other laboratory parameters, and none of the laboratory abnormalities were clinically significant.

Conclusion

No clinically meaningful changes in laboratory parameters were seen in adolescents, similar to that observed in adults. The findings of this study indicate no routine laboratory monitoring is required in this population prior to or during dupilumab treatment.

Trial Registration

ClinicalTrials.gov: NCT03054428.

Video Abstract

Eosinophilic Dermatoses: Recognition and Management

Eosinophilic dermatoses encompass a broad spectrum of diseases of different etiologies hallmarked by eosinophilic infiltration of the skin and/or mucous membranes, with or without associated blood eosinophilia. The wide range of dermatological manifestations of this spectrum, including nodules and plaques, pustules, blisters, ulcers, and urticarial lesions, is reflected in a non-univocal classification system. We identified six groups of eosinophilic dermatoses based on the predominant anatomic level of involvement: (1) epidermal; (2) of the dermal-epidermal junction; (3) dermal; (4) of the hypodermis and muscle fascia; (5) of the pilosebaceous unit; and (6) vascular/perivascular. We review clinicopathologic features and management of diseases belonging to each group, particularly: (1) pemphigus herpetiformis and atopic dermatitis as prototypes of the epidermal group; (2) bullous pemphigoid as prototypic eosinophilic dermatosis of the dermal-epidermal junction; (3) eosinophilic cellulitis (Wells syndrome), hypereosinophilic syndromes, Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS) syndrome, eosinophilic dermatosis of hematologic malignancy and chronic spontaneous urticaria as paradigmatic dermal eosinophilic dermatoses; (4) eosinophilic fasciitis as an eosinophilic dermatosis with predominant involvement of the hypodermis and muscle fascia; (5) eosinophilic pustular folliculitis as a model of the pilosebaceous unit involvement; and (6) granuloma faciale, angiolymphoid hyperplasia with eosinophilia, and eosinophilic granulomatosis with polyangiitis, belonging to the vascular/perivascular group.

A comparison of imaging software and conventional cell counting in determining melanocyte density in photodamaged control sample and melanoma in situ biopsies

BACKGROUND

Objective methods for distinguishing melanoma in situ (MIS) from photodamaged skin (PS) are needed to guide treatment in patients with melanocytic proliferations. Melanocyte density (MD) could serve as an objective histopathological criterion in difficult cases. Calculating MD via manual cell counts (MCC) with immunohistochemical (IHC)-stained slides has been previously published. However, the clinical application of this method is questionable, as quantification of MD via MCC on difficult cases is time consuming, especially in high volume practices.

METHODS

ImageJ is an image processing software that uses scanned slide images to determine cell count. In this study, we compared MCC to ImageJ calculated MD in microphthalmia transcription factor-IHC stained MIS biopsies and control PS acquired from the same patients.

RESULTS

We found a statistically significant difference in MD between PS and MIS as measured by both MCC and ImageJ software (P < 0.01). Additionally, no statistically significant difference was found when comparing MD measurements recorded by ImageJ vs those determined by the MCC method.

CONCLUSION

MD as determined by ImageJ strongly correlates with the MD calculated by MCC. We propose the use of ImageJ as a time-efficient, objective, and reproducible tool to assess MD.

IL-37 Ameliorating Allergic Inflammation in Atopic Dermatitis Through Regulating Microbiota and AMPK-mTOR Signaling Pathway-Modulated Autophagy Mechanism

Interaction between eosinophils and dermal fibroblasts is essential for provoking allergic inflammation in atopic dermatitis (AD). In vitro co-culture of human eosinophils and dermal fibroblasts upon AD-related IL-31 and IL-33 stimulation, and in vivo MC903-induced AD murine model were employed to investigate the anti-inflammatory mechanism of IL-1 family cytokine IL-37 in AD. Results showed that IL-37b could inhibit the in vitro induction of AD-related pro-inflammatory cytokines IL-6 and TNF-α, and chemokines CXCL8, CCL2 and CCL5, increase autophagosome biogenesis-related LC3B, and decrease autophagy-associated ubiquitinated protein p62 by regulating intracellular AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) signaling pathway. In CRISPR/Cas9 human IL-37b knock-in mice, IL-37b could significantly alleviate MC903-stimulated ear tissue swelling, itching sensation and the level of circulating cytokine IL-6 and ear in situ expression of AD-related TNF-α, CCL5 and transforming growth factor-β. Moreover, IL-37b could significantly upregulate Foxp3+ regulatory T cells (Treg) in spleen and ear together with significantly increased serum Treg cytokine IL-10, and decrease eosinophil infiltration in ear lesion. IL-37b knock-in mice showed a distinct intestinal microbiota metabolic pattern upon MC903 stimulation. Furthermore, IL-37b restored the disordered gut microbiota diversity, through regulating the in vivo autophagy mechanism mediated by intestinal metabolite 3-methyladenine, adenosine monophosphate, 2-hydroxyglutarate, purine and melatonin. In summary, IL-37b could significantly ameliorate eosinophils-mediated allergic inflammation via the regulation of autophagy mechanism, intestinal bacterial diversity and their metabolites in AD. Results therefore suggest that IL-37 is a potential anti-inflammatory cytokine for AD treatment.

Practical Approach to Children Presenting with Eosinophila and Hypereosinophilia

Eosinophilia is not a rare finding in clinical practice, and often poses problems in terms of etiologic research and differential diagnosis. Peripheral eosinophilia is defined by a blood eosinophil count > 500 cells/μL. It is classified into mild (500-1500 cells/μl), moderate (1500-5000 cells/μl) and severe for an eosinophil count > 5000 cells /μl. The term "hypereosinophilia" defines a condition characterized by a blood eosinophil count >1500 cells/μl in at least two consecutive tests made with a minimum of a 4-week interval. The causes of eosinophilia are various, and can be summarized by the acronym "APLV" which refers to Allergic disorders, Parasitic infections, Leukemia/ Lymphomas (and solid tumors) and Vasculitis-Immunodeficiency diseases, with allergic disorders and parasitic infections representing the most commonly identified causes. Allergic disorders are usually associated with mild eosinophilia, whereas values >20.000 cell/μl are highly suggestive for myeloproliferative disorders. Eosinophils may also be directly responsible for organ damage, mainly at cardiac, pulmonary and cutaneous level, deriving from the release of the granule products, of lipidic mediators and cytokines. Therefore, in the physician's approach to a patient with persistent hypereosinophilia, it is also important to investigate the presence of organ involvement. In this review, we propose a diagnostic algorithm for children presenting with either blood eosinophilia or hypereosinophilia. This algorithm focuses on the patient's history and clinical manifestations as the first step and the level and persistence of blood eosinophilia as the second, and this can help the physician to identify patients presenting with an elevated blood eosinophil count that need further laboratory or instrumental investigations.

Laboratory safety of dupilumab in moderate-to-severe atopic dermatitis: results from three phase III trials (LIBERTY AD SOLO 1, LIBERTY AD SOLO 2, LIBERTY AD CHRONOS)

Background

Dupilumab [a monoclonal antibody blocking the shared receptor subunit for interleukin (IL)‐4 and IL‐13] is approved for patients aged ≥ 12 years with inadequately controlled, moderate‐to‐severe atopic dermatitis (AD). Dupilumab trials of up to 52 weeks demonstrated efficacy and a favourable safety profile in patients with moderate‐to‐severe AD inadequately controlled with topical medications.

Objectives

To further characterize the safety of dupilumab by evaluating clinical laboratory findings from three randomized, double‐blinded, placebo‐controlled phase III trials (LIBERTY AD SOLO 1 & 2 and LIBERTY AD CHRONOS).

Methods

Patients were randomized 1 : 1 : 1 (SOLO 1 & 2) or 3 : 1 : 3 (CHRONOS) for 16 and 52 weeks, respectively, to dupilumab weekly, every 2 weeks or placebo. CHRONOS patients received a standardized concomitant topical corticosteroid regimen. Laboratory outcomes were summarized descriptively in 1376 patients from SOLO 1 & 2 and 740 from CHRONOS.

Results

Treatment groups had similar results in baseline laboratory parameters. Platelets and neutrophils showed mild decreases from baseline in dupilumab vs. placebo groups. Some dupilumab‐treated patients had small transient increases in eosinophils. Grade 3 eosinophilia was reported in < 1% of dupilumab‐treated and placebo‐treated patients; no adverse events were associated with eosinophilia. Lactate dehydrogenase levels decreased from baseline during dupilumab treatment in all trials. No clinically meaningful changes were observed between treatment groups in other haematology, chemistry or urinalysis parameters.

Conclusions

There were no clinically important changes in routine laboratory parameters that could be attributed to dupilumab. This study supports the use of dupilumab as a systemic treatment for moderate‐to‐severe AD that does not require laboratory monitoring.

What's already known about this topic?

Long‐term treatment of atopic dermatitis (AD) with conventional immunosuppressive agents is limited by the risk of significant side‐effects and a need for repeated tests to monitor haematological and/or organ (e.g. liver, kidney) toxicities.

Dupilumab [a monoclonal antibody blocking the shared receptor subunit for interleukin (IL)‐4 and IL‐13] is approved for the treatment of patients with inadequately controlled, moderate‐to‐severe AD.

In 16‐week and 52‐week studies, dupilumab demonstrated a positive risk/benefit profile in moderate‐to‐severe AD.

What does this study add?

This study is the first comprehensive analysis of dupilumab laboratory safety data of the 16‐week SOLO 1 & 2 (pooled N = 1376) and 52‐week CHRONOS (N = 740) trials, demonstrating an absence of clinically important changes in haematology, serum chemistry and urinalysis parameters in patients with moderate‐to‐severe AD treated with dupilumab.

Our data support the use of dupilumab as a systemic treatment for the long‐term management of moderate‐to‐severe AD without routine laboratory monitoring in clinical practice.

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Spontaneous atopic dermatitis in mice with a defective skin barrier is independent of ILC2 and mediated by IL-1β

BACKGROUND

Atopic dermatitis (AD) is one of the most common skin diseases with a multifactorial etiology. Mutations leading to loss of skin barrier function are associated with the development of AD with group 2 innate lymphoid cells (ILC2) promoting acute skin inflammation. Filaggrin-mutant (Flgft/ft ) mice develop spontaneous skin inflammation accompanied by an increase in skin ILC2 numbers, IL-1β production, and other cytokines recapitulating human AD. Here, we investigated the role of ILC2, effector cytokines, inflammasome activation, and mast cell function on the development of chronic AD-like inflammation in mice.

METHODS

Mice with a frameshift mutation in the filaggrin gene develop spontaneous dermatitis. Flgft/ft mice were crossed to cell- or cytokine-deficient mouse strains, or bred under germ-free conditions. Skin inflammation was scored, and microbiome composition was analyzed. Skin protein expression was measured by multiplex immunoassay. Infiltrating cells were analyzed by flow cytometry.

RESULTS

Wild-type and Flgft/ft mice significantly differ in their microbiome composition. Furthermore, mutant mice do not develop skin inflammation under germ-free conditions. ILC2 deficiency did not ameliorate chronic dermatitis in Flgft/ft mice, which was also independent of IL-4, IL-5, IL-9, IL-13, IL-17A, and IL-22. Inflammation was independent of NLRP3 inflammasome activation but required IL-1β and IL-1R1-signaling. Mechanistically, IL-1β promoted hyperactivation of IL-1R1-expressing mast cells. Treatment with anti-IL-1β-antibody alleviated dermatitis exacerbation, while antibiotic intervention ameliorated dermatitis in neonatal mice but not in adults with established inflammation.

CONCLUSIONS

In summary, we identified a critical role for the microbiome and IL-1β mediating chronic inflammation in mice with an impaired skin barrier.

Sulforaphane has a therapeutic effect in an atopic dermatitis murine model and activates the Nrf2/HO‑1 axis

Atopic dermatitis (AD), a chronic inflammatory skin disease, is characterized by intense itching and recurrent eczematous lesions. Sulforaphane is known to attenuate oxidative stress, and tissue or cell damage in cerebral ischemia, brain inflammation and intracerebral hemorrhage. In the present study, a 2,4‑dinitrochlorobenzene (DNCB)‑induced AD mouse model was developed, and ear thickness, dermatitis score, eosinophil count, mast cell infiltration, and serum IgE levels were measured in DNCB‑induced AD and sulforaphane‑treated groups to demonstrate the therapeutic effects of sulforaphane. AD symptoms of DNCB‑induced mice were attenuated by sulforaphane treatment compared with those of negative control mice; furthermore, eosinophil count, mast cell infiltration and serum IgE levels were also reduced by sulforaphane treatment in DNCB‑induced AD mice. Western blot assays revealed that the expression levels of nuclear factor‑E2‑related factor 2 (Nrf2) and heme oxygenase-1 (HO‑1), which exhibit oxidation resistance, were increased by sulforaphane treatment in DNCB‑induced AD mice. The present study suggested that sulforaphane exerted a therapeutic effect in the AD mouse model through the activation of the Nrf2/HO‑1 axis as well as the suppression of Janus kinase 1/STAT3 signaling pathway.

Evaluation of Peripheral Blood Eosinophilia in Adolescent and Adult Patients Suffering from Atopic Dermatitis and the Relation to the Occurrence of Allergy to Aeroallergens

Background:

Eosinophils play an important pathogenic role in atopic dermatitis (AD), but its exact function remains to be determined.

Aims and Objectives:

The aim of this study was to correlate the eosinophil count with the manifestations such as asthma bronchiale, rhinitis, level of total IgE, sensitization to mites, animal dander, bird feather, dust, mixture of grass, mixture of trees, mixture of fungi, duration of lesions (persistent or occasional during last year), family history about atopy, and onset of AD (under or above 5 year of age).

Materials and Methods:

Two hundred and seventy-two patients suffering from AD at the age of 14 year or older were examined – 100 men and 172 women with the average age of 26.7±9.5 years and with the average SCORAD index of 32.9±14.1. Complete dermatological and allergological examinations were performed in all patients with the evaluation of monitored manifestations. Mann–Whitney test for difference in medians was used for statistical evaluation.

Results:

The count of eosinophils in peripheral blood was significantly higher in patients with total IgE ≥200 IU/ml, with sensitization to dust, with persistent eczematous lesions and in patients with the onset of AD under 5 year of age. The count of eosinophils above 5% was recorded as well in patients suffering from asthma bronchiale, rhinitis, sensitization to mites, and in patients with positive family history about atopy, but the difference was not significant. On the other hand, the count of eosinophils was under 5% in patients with sensitization to animal dander, bird feather, mixture of grass and trees.

Conclusion:

Our results demonstrated the difference in the count of eosinophils in peripheral blood according to different manifestations in patients suffering from AD.

Biologic Therapies for Immunoglobulin E-mediated Food Allergy and Eosinophilic Esophagitis

Immunoglobulin (Ig) E-mediated food allergy and eosinophilic esophagitis (EoE) are chronic, allergen-mediated disorders characterized by an aberrant TH2 immune response. The development and investigation of biologics for the treatment of IgE-mediated food allergy and eosinophilic esophagitis have provided further insight into the pathophysiology and management of these disorders. This article provides an overview of biologic therapies that are being investigated or have potential as treatments for IgE-mediated food allergy and eosinophilic esophagitis. Identification of EoE phenotypes that are responsive to biologics and investigation of biologics combined with other therapies may help elucidate a role for biologics in EoE.

Interleukin-13 in Asthma and Other Eosinophilic Disorders

Asthma is characterized by episodic, reversible airflow obstruction associated with variable levels of inflammation. Over the past several decades, there has been an increasing appreciation that the clinical presentation of asthma comprises a diverse set of underlying pathologies. Rather than being viewed as a single disease entity, asthma is now thought of as a clinical syndrome with the involvement of multiple pathological mechanisms. While it is appreciated that eosinophilia is present in only a subset of patients, it remains a key feature of asthma and other eosinophilic disorders such as atopic dermatitis, eosinophilic esophagitis, and chronic rhinosinusitis with nasal polyps. Eosinophils are bone marrow-derived leukocytes present in low numbers in health; however, during disease the type 2 cytokines [interleukins (IL)-4, -5, and -13] can induce rapid eosinophilopoiesis, prolonged eosinophil survival, and trafficking to the site of injury. In diseases such as allergic asthma there is an aberrant inflammatory response leading to eosinophilia, tissue damage, and airway pathology. IL-13 is a pleiotropic type 2 cytokine that has been shown to be integral in the pathogenesis of asthma and other eosinophilic disorders. IL-13 levels are elevated in animal models of eosinophilic inflammation and in the blood and tissue of patients diagnosed with eosinophilic disorders. IL-13 signaling elicits many pathogenic mechanisms including the promotion of eosinophil survival, activation, and trafficking. Data from preclinical models and clinical trials of IL-13 inhibitors in patients have revealed mechanistic insights into the role of this cytokine in driving eosinophilia. Promising results from clinical trials further support a key mechanistic role of IL-13 in asthma and other eosinophilic disorders. Here, we provide a perspective on the role of IL-13 in asthma and other eosinophilic disorders and describe ongoing clinical trials targeting this pathway in patients with significant unmet medical needs.

Eosinophil-derived neurotoxin as a biomarker for disease severity and relapse in recalcitrant atopic dermatitis

BACKGROUND

Eosinophils are encountered in many skin diseases, but the role of eosinophils in atopic dermatitis (AD) remains uncertain.

OBJECTIVE

To examine the role of serum eosinophil-derived neurotoxin (EDN), eosinophil cationic protein (ECP), and total IgE as a biomarker of disease severity and relapse in severe recalcitrant AD.

METHODS

We enrolled 99 patients with AD: 37 with severe recalcitrant AD, 20 with severe AD, and 42 with mild to moderate AD. We examined the difference in serum level of total IgE, ECP, and EDN between the groups and whether any correlation existed between disease severity and ECP or EDN. Lastly, difference in levels of ECP or EDN between those who experienced relapse was examined in the severe recalcitrant group.

RESULTS

Serum levels of total IgE, ECP, and EDN were significantly higher in the severe recalcitrant AD group and severe AD group compared with the mild to moderate AD group. No significant difference was found in serum levels of total IgE, ECP, and EDN between the severe recalcitrant group and severe group. EDN had a significant positive correlation with the SCORing Atopic Dermatitis. No significant correlation was found between EDN and ECP. In the severe recalcitrant group, 29.7% of patients experienced relapse, and EDN was significantly higher in those who experienced relapse. The cutoff value of EDN for predicting relapse was 64.5.

CONCLUSION

EDN correlated with the disease severity of AD. EDN may predict relapse in severe recalcitrant AD. The EDN serum level could be considered a candidate molecule as a clinical biomarker for evaluating AD disease activity and a predictor of relapse.

Cellular and molecular immunologic mechanisms in patients with atopic dermatitis

Atopic dermatitis (AD) is a complex skin disease frequently associated with other diseases of the atopic diathesis. Recent evidence supports the concept that AD can also recognize other comorbidities, such as chronic inflammatory bowel or cardiovascular diseases. These comorbidities might result from chronic cutaneous inflammation or from a common, yet-to-be-defined immunologic background leading to immune deviations. The activation of immune cells and their migration to the skin play an essential role in the pathogenesis of AD. In patients with AD, an underlying immune deviation might result in higher susceptibility of the skin to environmental factors. There is a high unmet medical need to define immunologic endotypes of AD because it has significant implications on upcoming stratification of the phenotype of AD and the resulting targeted therapies in the development of precision medicine. This review article emphasizes studies on environmental factors affecting AD development and novel biological agents used in the treatment of AD. Best evidence of the clinical efficacy of novel immunologic approaches using biological agents in patients with AD is available for the anti-IL-4 receptor α-chain antibody dupilumab, but a number of studies are currently ongoing with other specific antagonists to immune system players. These targeted molecules can be expressed on or drive the cellular players infiltrating the skin (eg, T lymphocytes, dendritic cells, or eosinophils). Such approaches can have immunomodulatory and thereby beneficial clinical effects on the overall skin condition, as well as on the underlying immune deviation that might play a role in comorbidities. An effect of these immunologic treatments on pruritus and the disturbed microbiome in patients with AD has other potential consequences for treatment.

Commonality of the IL-4/IL-13 pathway in atopic diseases

INTRODUCTION

Allergy results from an aberrant Type 2 inflammatory response, triggered by a wide range of environmental antigens (allergens) that lead to various immune responses, culminating in the production of immunoglobulin E (IgE). Two key cytokines, interleukin (IL)-4 and IL-13, are critical to the induction and perpetuation of the Type 2 response, and have been implicated in multiple atopic diseases. Area covered: This review summarizes recent milestone developments that have elucidated components of the pathogenesis of atopic diseases such as atopic dermatitis (AD), asthma, and chronic sinusitis with nasal polyposis (CSwNP). Expert commentary: Several therapeutic agents that selectively target potentiators of the Type 2 pathway have shown efficacy in one or more of these atopic diseases, but few agents have proven to be broadly applicable across all three atopic diseases. Dupilumab, a human monoclonal antibody that simultaneously inhibits signaling of IL-4 and IL-13, has demonstrated significant clinical efficacy in AD, asthma, and CSwNP. The fact that these diseases often occur as comorbidities and respond to the same therapy suggests that there is a common underlying pathogenic pathway, and that IL-4 and IL-13 cytokines are central to regulating the pathogenesis of these atopic diseases.

Anti-Inflammatory Activities of Pentaherbs Formula, Berberine, Gallic Acid and Chlorogenic Acid in Atopic Dermatitis-Like Skin Inflammation

Atopic dermatitis (AD) is a common allergic skin disease, characterized by dryness, itchiness, thickening and inflammation of the skin. Infiltration of eosinophils into the dermal layer and presence of edema are typical characteristics in the skin biopsy of AD patients. Previous in vitro and clinical studies showed that the Pentaherbs formula (PHF) consisting of five traditional Chinese herbal medicines, Flos Lonicerae, Herba Menthae, Cortex Phellodendri, Cortex Moutan and Rhizoma Atractylodis at w/w ratio of 2:1:2:2:2 exhibited therapeutic potential in treating AD. In this study, an in vivo murine model with oxazolone (OXA)-mediated dermatitis was used to elucidate the efficacy of PHF. Active ingredients of PHF water extract were also identified and quantified, and their in vitro anti-inflammatory activities on pruritogenic cytokine IL-31- and alarmin IL-33-activated human eosinophils and dermal fibroblasts were evaluated. Ear swelling, epidermis thickening and eosinophils infiltration in epidermal and dermal layers, and the release of serum IL-12 of the murine OXA-mediated dermatitis were significantly reduced upon oral or topical treatment with PHF (all p < 0.05). Gallic acid, chlorogenic acid and berberine contents (w/w) in PHF were found to be 0.479%, 1.201% and 0.022%, respectively. Gallic acid and chlorogenic acid could suppress the release of pro-inflammatory cytokine IL-6 and chemokine CCL7 and CXCL8, respectively, in IL-31- and IL-33-treated eosinophils-dermal fibroblasts co-culture; while berberine could suppress the release of IL-6, CXCL8, CCL2 and CCL7 in the eosinophil culture and eosinophils-dermal fibroblasts co-culture (all p < 0.05). These findings suggest that PHF can ameliorate allergic inflammation and attenuate the activation of eosinophils.

Eosinophilia in Dermatologic Disorders

Eosinophil infiltration can be observed in skin disorders, such as allergic/immunologic, autoimmune, infectious, and neoplastic diseases. Clinical presentations are variable and include eczematous, papular, urticarial, bullous, nodular, and fibrotic lesions; pruritus is a common symptom in all. In this review, we present representative eosinophilic skin diseases according to their clinical pattern, together with histologic findings and diagnostic procedures. We also discuss the potential roles of eosinophils in the pathogenesis of dermatologic disorder. Current pathogenesis-based diagnostic and therapeutic approaches are outlined.

Mast cells are dispensable in a genetic mouse model of chronic dermatitis

Chronic inflammatory skin diseases, such as atopic dermatitis, affect a large percentage of the population, but the role of different immune cells in the pathogenesis of these disorders is largely unknown. Recently, we found that mice lacking fibroblast growth factor receptor 1 (Fgfr1) and Fgfr2 (K5-R1/R2 mice) in the epidermis have a severe impairment in the epidermal barrier, which leads to the development of a chronic inflammatory skin disease that shares many features with human atopic dermatitis. Using Fgfr1-/Fgfr2-deficient mice, we analyzed the consequences of the loss of mast cells. Mast cells accumulated and degranulated in the skin of young Fgfr1-/Fgfr2-deficient mice, most likely as a consequence of increased expression of the mast cell chemokine Ccl2. The increase in mast cells occurred before the development of histological abnormalities, indicating a functional role of these cells in the inflammatory skin phenotype. To test this hypothesis, we mated the Fgfr1-/Fgfr2-deficient mice with mast cell-deficient CreMaster mice. Surprisingly, loss of mast cells did not or only mildly affect keratinocyte proliferation, epidermal thickness, epidermal barrier function, accumulation and activation of different immune cells, or expression of different proinflammatory cytokines in the skin. These results reveal that mast cells are dispensable for the development of chronic inflammation in response to a defect in the epidermal barrier.

Molecular biology of atopic dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease with specific genetic and immunological mechanisms. The rapid development of new techniques in molecular biology had ushered in new discoveries on the role of cytokines, chemokines, and immune cells in the pathogenesis of AD. New polymorphisms of AD are continually being reported in different populations. The physical and immunological barrier of normal intact skin is an important part of the innate immune system that protects the host against microbials and allergens that are associated with AD. Defects in the filaggrin gene FLG may play a role in facilitating exposure to allergens and microbial pathogens, which may induce Th2 polarization. Meanwhile, Th22 cells also play roles in skin barrier impairment through IL-22, and AD is often considered to be a Th2/Th22-dominant allergic disease. Mast cells and eosinophils are also involved in the inflammation via Th2 cytokines. Release of pruritogenic substances by mast cells induces scratching that further disrupts the skin barrier. Th1 and Th17 cells are mainly involved in chronic phase of AD. Keratinocytes also produce proinflammatory cytokines such as thymic stromal lymphopoietin (TSLP), which can further affect Th cells balance. The immunological characteristics of AD may differ for various endotypes and phenotypes. Due to the heterogeneity of the disease, and the redundancies of these mechanisms, our knowledge of the pathophysiology of the disease is still incomplete, which is reflected by the absence of a cure for the disease.

Skin-specific expression of IL-33 activates group 2 innate lymphoid cells and elicits atopic dermatitis-like inflammation in mice

Transgenic mice expressing the mouse interleukin 33 (IL-33) gene driven by a keratin 14 promoter were generated. The skin-selective expression of the IL-33 gene was enhanced, and intense immunofluorescence for IL-33 was evident in the nuclei of the epidermis. Spontaneous itchy dermatitis developed in those mice at 6-8 wk of age in specific pathogen-free conditions. In the lesional skin, the epidermis was thickened and the eosinophils were infiltrated with increased expression of the eosinophil peroxidase and major basic protein genes. Mast cells were also abundant there, and blood histamine and total IgE levels were high. Those phenotypes closely resemble the features of atopic dermatitis. In peripheral blood and lesional skin, IL-5, IL-13, regulated upon activation, normally T-expressed, and presumably secreted (RANTES)/CCL5, and Eotaxin 1/CCL11 were increased, whereas TNF-α, IFN-γ, and thymic stromal lymphopoietin (TSLP) were unaltered. Furthermore, the proportion of group 2 innate lymphoid cells (ILC2s), which produce IL-5, were significantly increased in the lesional skin, peripheral blood, and regional lymph nodes. The dermatitis with eosinophil infiltration was improved by the administration of an anti-IL-5 antibody. These results suggest that the expression of IL-33 in the skin activates an immune response involving ILC2 and that this process might play a crucial role in the pathogenesis of allergic inflammation that is characteristic of atopic dermatitis.

Tumor necrosis factor-α, monocyte chemoattractant protein-1 and intercellular adhesion molecule-1 increase during the development of a 2,4-dinitrofluorobenzene-induced immediate-type dermatitis in rats

BACKGROUND

Due to the steadily increasing incidence of atopic dermatitis, there is a great medical need for new therapies and improved animal models.

OBJECTIVE

To provide more detailed analysis of a Sprague-Dawley rat dermatitis model.

METHODS

Sprague-Dawley rats were actively sensitized by intraperitoneal injections of dinitrophenylated ovalbumin (DNP-OVA) plus alum. Skin reactions were elicited by repeated epicutaneous challenge with 2,4-dinitrofluorobenzene (DNFB).

RESULTS

The ear thickness exhibited a significant increase from the first challenge. A relatively steep increase in ear thickness was observed at the fifth DNFB application. After the fifth DNFB application, total serum immunoglobulin (Ig) E and IgG1 levels reached a plateau at 1 h compared with the normal group. The peak production of tumor necrosis factor (TNF)-α and monocyte chemoattractant protein (MCP)-1 was found at 1 h, while that of intercellular adhesion molecule (ICAM)-1 was found at 24 h. Infiltration of CD4+ T cells, CD8+ T cells, eosinophils and mast cells increased in the skin lesion.

CONCLUSIONS

The indices such as thickness and inflammatory cell infiltration in the lesional skin were increased by repeated hapten application; TNF-α, MCP-1 and ICAM-1 increased with the development of the dermatitis.

Staphylococcus aureus directly activates eosinophils via platelet-activating factor receptor

Colonization by SA is associated with exacerbation of AD. Eosinophilic inflammation is a cardinal pathological feature of AD, but little is known about possible direct interaction between SA and eosinophils. PAFR appears to be involved in phagocytosis of Gram-positive bacteria by leukocytes. The objective of this study was to investigate whether SA directly induces eosinophil effector functions via PAFR in the context of AD pathogenesis. Peripheral blood eosinophils were cultured with heat-killed SA, and EDN release, superoxide generation, and adhesion to fibronectin-coated plates were measured. Cytokines, released in the supernatants, were quantified by multiplex bead immunoassays. FISH-labeled SA was incubated with eosinophils and visualized by confocal laser-scanning microscopy. PAFR-blocking peptide and PAFR antagonists were tested for inhibitory effects on SA-induced reactions. SA induced EDN release and superoxide generation by eosinophils in a dose-dependent manner. IL-5 significantly enhanced SA-induced EDN release. IL-5 and IL-17A significantly enhanced SA-induced superoxide generation. SA enhanced eosinophil adhesion to fibronectin, which was blocked by anti-CD49d, and induced eosinophil secretion of various cytokines/chemokines (IL-2R, IL-9, TNFR, IL-1 β, IL-17A, IP-10, TNF-α, PDGF-bb, VEGF, and FGF-basic). After incubation of eosinophils with SA, FISH-labeled SA was visualized in the eosinophils' cytoplasm, indicating phagocytosis. A PAFR-blocking peptide and two PAFR antagonists completely inhibited those reactions. In conclusion, SA directly induced eosinophil activation via PAFR. Blockade of PAFR may be a novel, therapeutic approach for AD colonized by SA.

Activation of eosinophils interacting with dermal fibroblasts by pruritogenic cytokine IL-31 and alarmin IL-33: implications in atopic dermatitis

BACKGROUND

IL-31 is a pruritogenic cytokine, and IL-33 is an alarmin for damaging inflammation. They together relate to the pathogenesis of atopic dermatitis (AD). Eosinophil infiltration into the inner dermal compartment is a predominant pathological feature of AD. We herein investigated the in vitro inflammatory effects of IL-31 and IL-33 on the activation of human eosinophils and dermal fibroblasts.

METHODOLOGY/PRINCIPAL FINDINGS

Receptors, adhesion molecules and signaling molecules were assessed by Western blot or flow cytometry. Chemokines and cytokine were quantitated by multiplex assay. Functional IL-31 receptor component IL-31RA, OSMR-β and IL-33 receptor component ST2 were constitutively expressed on the surface of eosinophils. Co-culture of eosinophils and fibroblasts significantly induced pro-inflammatory cytokine IL-6 and AD-related chemokines CXCL1, CXCL10, CCL2 and CCL5. Such inductions were further enhanced with IL-31 and IL-33 stimulation. IL-31 and IL-33 could significantly provoke the release of CXCL8 from eosinophils and fibroblasts, respectively, which was further enhanced upon co-culture. In co-culture, eosinophils and fibroblasts were the main source for the release of CCL5, and IL-6, CXCL1, CXCL8, CXCL10 and CCL2, respectively. Direct interaction between eosinophils and fibroblasts was required for CXCL1, CXCL10, CXCL8 and CCL5 release. Cell surface expression of intercellular adhesion molecule-1 on eosinophils and fibroblasts was up-regulated in co-culture upon IL-31 and IL-33 stimulation. The interaction between eosinophils and fibroblasts under IL-31 and IL-33 stimulation differentially activated extracellular signal-regulated kinase, c-Jun N-terminal kinase, p38 mitogen-activated protein kinase, nuclear factor-κB and phosphatidylinositol 3-kinase-Akt pathways. Using specific signaling molecule inhibitors, the differential induction of IL-31 and IL-33-mediated release of cytokines and chemokines such as IL-6 and CXCL8 from co-culture should be related to their distinct activation profile of intracellular signaling pathways.

CONCLUSIONS/SIGNIFICANCE

The above findings suggest a crucial immunopathological role of IL-31 and IL-33 in AD through the activation of eosinophils-fibroblasts interaction via differential intracellular signaling mechanisms.

Molecular and clinical rationale for therapeutic targeting of interleukin-5 and its receptor

Interleukin-5 is a Th2 homodimeric cytokine involved in the differentiation, maturation, migration, development, survival, trafficking and effector function of blood and local tissue eosinophils, in addition to basophils and mast cells. The IL-5 receptor (IL-5R) consists of an IL-5-specific α subunit that interacts in conformationally dynamic ways with the receptor's βc subunit, an aggregate of domains it shares with binding sites of IL-3 and granulocyte-macrophage colony-stimulating factor. IL-5 and IL-5R drive allergic and inflammatory immune responses characterizing numerous diseases, such as asthma, atopic dermatitis, chronic obstructive pulmonary disease, eosinophilic gastrointestinal diseases, hyper-eosinophilic syndrome, Churg-Strauss syndrome and eosinophilic nasal polyposis. Although corticosteroid therapy is the primary treatment for these diseases, a substantial number of patients exhibit incomplete responses and suffer side-effects. Two monoclonal antibodies have been designed to neutralize IL-5 (mepolizumab and reslizumab). Both antibodies have demonstrated the ability to reduce blood and tissue eosinophil counts. One additional monoclonal antibody, benralizumab (MEDI-563), has been developed to target IL-5R and attenuate eosinophilia through antibody-dependent cellular cytotoxicity. All three monoclonal antibodies are being clinically evaluated. Antisense oligonucleotide technology targeting the common βc IL-5R subunit is also being used therapeutically to inhibit IL-5-mediated effects (TPI ASM8). Small interfering RNA technology has also been used therapeutically to inhibit the expression of IL-5 in animal models. This review summarizes the structural interactions between IL-5 and IL-5R and the functional consequences of such interactions, and describes the pre-clinical and clinical evidence supporting IL-5R as a therapeutic target.

[Inflammatory dermatoses]

The seven basic patterns of inflammatory dermatoses according to Ackerman can be applied to infectious dermatoses. However, it should be borne in mind that infection caused by one agent may induce differing patterns according to the stage of disease. Dermatophytosis and the arthropod reaction belong to perivascular dermatoses with spongiosis. Secondary syphilis and acrodermatitis chronica atrophicans regularly show a lichenoid infiltrate with interface dermatitis, whereas epidermal involvement is typically absent in erythema migrans, virus exanthema and bacillary angiomatosis. Lupus vulgaris, atypic mycobacteriosis, lepra, actinomycosis, cutaneous leishmaniosis and erysipelas belong to the nodular and diffuse dermatoses. In the group of vasculitides, septic vasculitis is induced by a biological agent, and the pattern of vesicular dermatitis is reflected by infections with herpes viruses, impetigo contagiosa and staphylococcal scalded-skin syndrome. Follicular dermatitis shows a pattern of furuncles and carbuncles which are mainly caused by bacteria or fungi.

Eosinophils increase neuron branching in human and murine skin and in vitro

Cutaneous nerves are increased in atopic dermatitis, and itch is a prominent symptom. We studied the functional interactions between eosinophils and nerves in human and mouse skin and in culture. We demonstrated that human atopic dermatitis skin has eosinophil granule proteins present in the same region as increased nerves. Transgenic mice in which interleukin-5 (IL-5) expression is driven by a keratin-14 (K14) promoter had many eosinophils in the epidermis, and the number of nerves was also significantly increased in the epidermis. In co-cultures, eosinophils dramatically increased branching of sensory neurons isolated from the dorsal root ganglia (DRG) of mice. This effect did not occur in DRG neurons co-cultured with mast cells or with dead eosinophils. Physical contact of the eosinophils with the neurons was not required, and the effect was not blocked by an antibody to nerve growth factor. DRG neurons express eotaxin-1, ICAM-1 and VCAM-1, which may be important in the recruitment, binding, and activation of eosinophils in the region of cutaneous nerves. These data indicate a pathophysiological role for eosinophils in cutaneous nerve growth in atopic dermatitis, and suggest they may present a therapeutic target in atopic dermatitis and other eosinophilic skin conditions with neuronal symptoms such as itch.