Alterations in B-cell subsets in pediatric patients with early atopic dermatitis

Differences in immunological profile in atopic dermatitis patients with and without dupilumab therapy

Our aim is to determine the number of leukocytes, T lymphocytes and B lymphocytes and the expression of activation markers CD200 and CD23 on B lymphocytes in atopic dermatitis (AD) patients (treated and not treated with dupilumab) during the pollen season. We examined 29 patients not treated with dupilumab, 24 patients treated with dupilumab and 40 healthy subjects as a control group. The count of T and B lymphocytes and their subsets were assessed by flow cytometry. The non-parametric Kruskal-Wallis one-factor analysis of variance with post hoc by Dunn's test with Bonferroni's modification was used for statistical processing. Although there was a significant improvement in skin findings in patients treated with dupilumab, the changes in immunological profile show a persistent altered immune response characterized by dysregulation and overactivation of B lymphocytes. Dupilumab therapy leads to normalization of relative T regulatory lymphocytes and total memory B lymphocytes and to decreased count of absolute CD8+ T lymphocytes. Why carry out this study?Studies investigating the immunological profile of atopic dermatitis (AD) patients during the pollen season are rare. There are no studies investigating the count of B lymphocytes (CD5+, CD22+ and CD73+ B lymphocytes) and the expression of activation markers CD23 and CD200 on B lymphocytes and on their subsets during pollen season in AD patients treated and non-treated with dupilumab therapy.What was learned from the study?In atopic dermatitis (AD) patients with and without dupilumab therapy, we confirmed the significantly higher count of absolute neutrophils, absolute monocytes, absolute eosinophils, absolute basophils, non-switched B lymphocytes, transitional B lymphocytes, CD23 memory, naive, non-switched, switched and total CD23 B lymphocytes, the relative count of CD200 memory and CD200 switched B lymphocytes.In dupilumab treated patients, we confirmed the significantly higher count of relative eosinophils, relative CD16+ eosinophils, relative CD200 non-switched B lymphocytes and lower count of absolute CD8+ T lymphocytes. Further studies should focus on investigating the effect of dupilumab on CD8+ T lymphocytes and their subpopulations.In patients without dupilumab therapy, we confirmed the significantly higher count of relative neutrophils, relative T regulatory lymphocytes and total memory B lymphocytes.The changes in the count of CD5+, CD22+ and CD73+ B lymphocytes were not observed during pollen season in both groups of AD patients.

Atopic dermatitis

Atopic dermatitis is the most common chronic inflammatory skin disease globally. Key features include an eczematous eruption accompanied by intense itch, which can have an enormous negative effect on patients' quality of life, especially in those with moderate-to-severe disease. Atopic dermatitis is part of a spectrum of atopic conditions that can also include several non-cutaneous organs such as respiratory (eg, allergic rhinitis and asthma) and gastrointestinal (eg, food allergy) systems. For decades, long-term disease control and maintenance were particularly challenging given that treatment options were limited to broad topical and systemic immunosuppressive agents. However, better insights into the pathophysiology of this condition over the past decade have led to the development and approval of safe and efficacious novel targeted treatment approaches. The updated pathophysiological understanding and the evolving therapeutic landscape of atopic dermatitis are discussed in this Seminar.

Evolution of pathologic B-cell subsets and serum environment-specific sIgEs in patients with atopic dermatitis and controls, from infancy to adulthood

BACKGROUND

While B-cells have historically been implicated in allergy development, a growing body of evidence supports their role in atopic dermatitis (AD). B-cell differentiation across ages in AD, and its relation to disease severity scores, has not been well defined.

OBJECTIVE

To compare the frequency of B-cell subsets in blood of 0-5, 6-11, 12-17, and ≥18 years old patients with AD versus age-matched controls.

METHODS

Flow cytometry was used to measure B-cell subset frequencies in the blood of 27 infants, 17 children, 11 adolescents, and 31 adults with moderate-to-severe AD and age-matched controls. IgD/CD27 and CD24/CD38 core gating systems and an 11-color flow cytometry panel were used to determine frequencies of circulating B-cell subsets. Serum total and allergen-specific IgE (sIgEs) levels were measured using ImmunoCAP®.

RESULTS

Adolescents with AD had lower frequencies of major B-cells subsets (p < .03). CD23 expression increased with age and was higher in AD compared to controls across all age groups (p < .04). In AD patients, multiple positive correlations were observed between IL-17-producing T-cells and B-cell subsets, most significantly non-switched memory (NSM) B-cells (r = .41, p = .0005). AD severity positively correlated with a list of B-cell subsets (p < .05). IL-9 levels gradually increased during childhood, reaching a peak in adolescence, paralleling allergen sensitization, particularly in severe AD. Principal component analysis of the aggregated environmental sIgE data showed that while controls across all ages tightly clustered together, adolescents with AD demonstrated distinct clustering patterns relative to controls.

CONCLUSIONS

Multiple correlations between B-cells and T-cells, as well as disease severity measures, suggest a complex interplay of immune pathways in AD. Unique B-cell signature during adolescence, with concurrent allergen sensitization and IL-9 surge, point to a potentially wider window of opportunity to implement interventions that may prevent the progression of the atopic march.

The causal relationship between immune cells and atopic dermatitis: A bidirectional Mendelian randomization study

BACKGROUND

Atopic dermatitis (AD) is a chronic inflammatory skin condition whose origins remain unclear. Existing epidemiological evidence suggests that inflammation and immune factors play pivotal roles in the onset and progression of AD. However, previous research on the connection between immune inflammation and AD has yielded inconclusive results.

METHODS

To evaluate the causal relationship between immunological characteristics and AD, this study employed a bidirectional, two-sample Mendelian randomization (MR) approach. We utilized large-scale, publicly available genome-wide association studies to investigate the causal associations between 731 immunological feature cells and the risk of AD.

RESULTS

Significant associations were identified between six immune phenotypes and AD risk: increased Basophil %CD33dim HLA DR-CD66b-, CD25 on IgD+ CD24+, CD40 on monocytes, HLA DR on CD14+ CD16-monocytes, HLA DR on CD14+monocytes correlated with higher AD risk, while elevated CD3 on CD4 Treg was linked to lower risk. Reverse MR analysis revealed AD as a risk factor for IgD+ CD38br AC and IgD+ CD38br %B cell, but a protective factor against CD20 on IgD+ CD38- naive and CD8 on NKT.

CONCLUSION

Our findings elucidate the intricate interplay between immune cells and AD, informing future research into AD pathophysiology and therapeutics.

The Role of Inhalant Allergens on the Clinical Manifestations of Atopic Dermatitis

BACKGROUND

Inhalant allergens provide a source of environmental factors that contribute to the development of clinical symptoms in patients with atopic dermatitis (AD).

OBJECTIVE

To review the relationship between inhalant allergens and AD.

METHODS

A literature review was conducted using three databases: PubMed/MEDLINE, ClinicalKey, and Web of Science. Search terms, including "atopic dermatitis," "atopic eczema," and "eczema," were used in combination with "inhalant allergen," "inhaled allergen," and "aeroallergen" to identify relevant published manuscripts that highlight the relationship between AD and exposures to inhalant allergens.

RESULTS

Fifteen articles were suitable for review. The studies included in the review investigated the effect of inhalant allergens on the clinical manifestations of AD through bronchial provocation, direct skin contact, and allergen sensitization.

CONCLUSION

There is a significant relationship between exposures to inhalant allergens and AD. Inhalant allergens may aggravate AD symptoms by either bronchial provocation or direct skin contact. Sensitization of inhalant allergens, mainly house dust mites, follows a specific age-related pattern.

Genetic and Immunological Pathogenesis of Atopic Dermatitis

Type 2 immune-mediated diseases give a clear answer to the issue of nature (genetics) versus nurture (environment). Both genetics and environment play vital complementary roles in the development of atopic dermatitis (AD). As a key component of the atopic march, AD demonstrates the interactive nature of genetic and environmental contributions to atopy. From sequence variants in the epithelial barrier gene encoding FLG to the hygiene hypothesis, AD combines a broad array of contributions into a single syndrome. This review will focus on the genetic contribution to AD and where genetics facilitates the elicitation or enhancement of AD pathogenesis.

CD23+IgG1+ memory B cells are poised to switch to pathogenic IgE production in food allergy

Food allergy is caused by allergen-specific immunoglobulin E (IgE) antibodies, but little is known about the B cell memory of persistent IgE responses. Here, we describe, in human pediatric peanut allergy, a population of CD23+IgG1+ memory B cells arising in type 2 immune responses that contain high-affinity peanut-specific clones and generate IgE-producing cells upon activation. The frequency of CD23+IgG1+ memory B cells correlated with circulating concentrations of IgE in children with peanut allergy. A corresponding population of "type 2-marked" IgG1+ memory B cells was identified in single-cell RNA sequencing experiments. These cells differentially expressed interleukin-4 (IL-4)- and IL-13-regulated genes, such as FCER2/CD23+, IL4R, and germline IGHE, and carried highly mutated B cell receptors (BCRs). In children with high concentrations of serum peanut-specific IgE, high-affinity B cells that bind the main peanut allergen Ara h 2 mapped to the population of "type 2-marked" IgG1+ memory B cells and included clones with convergent BCRs across different individuals. Our findings indicate that CD23+IgG1+ memory B cells transcribing germline IGHE are a unique memory population containing precursors of high-affinity pathogenic IgE-producing cells that are likely to be involved in the long-term persistence of peanut allergy.

Evaluation of Leukocytes, B and T Lymphocytes, and expression of CD200 and CD23 on B lymphocytes in Patients with Atopic Dermatitis on Dupilumab Therapy-Pilot Study

BACKGROUND

There are a lot of studies that describe the change in quantity of T cells in patients with atopic dermatitis (AD) compared with healthy subjects. Other components of lymphocytes such as B cells are not examined as well as T cells.

OBJECTIVE

We focus on immunophenotyping of B cells with their subsets (memory, naïve, switched, non-switched) and the expression of CD23 and CD200 markers in patients with AD with and without dupilumab therapy. We also evaluate the count of leukocytes and their subsets, T lymphocytes (CD4⁺, CD8⁺), natural killer (NK) cells, and T regulatory cells.

METHODS

A total of 45 patients suffering from AD were examined: 32 patients without dupilumab treatment (10 men, 22 women, average age 35 years), 13 patients with dupilumab treatment (7 men, 6 women, average age 43.4 years), and 30 subjects as a control group (10 men, 20 women, average age 44.7 years). Immunophenotype was examined by flow cytometry in which monoclonal antibodies with fluorescent molecules were used. We compared the absolute and relative count of leukocytes and their subsets, T lymphocytes (CD4⁺ , CD8⁺), NK cells, T regulatory cells, absolute and relative count of B lymphocytes (memory, naïve, non-switched, switched, transient), and expression of CD23 and CD200 activation markers on B cells and on their subsets in patients with AD and control group. For statistical analysis we used nonparametric Kruskal-Wallis one-factor analysis of variance with post hoc by Dunn's test with Bonferroni modification of significance level.

RESULTS

In patients with AD with and without dupilumab therapy we confirmed the significantly higher count of neutrophils, monocytes, and eosinophils; there was no difference in absolute count of B cells, NK cells and transitional B cells compared with control subjects. We confirmed higher expression of activation marker CD23 on total, memory, naïve, non-switched, and switched B lymphocytes and higher expression of CD200 on total B lymphocytes in both groups of patients with AD compared with controls. In patients without dupilumab therapy we confirmed significantly higher count of relative monocytes, relative eosinophils, and higher expression of CD200 on memory, naïve, and non-switched B lymphocytes compared with controls. In patients with dupilumab therapy we confirmed significantly higher expression of CD200 on switched B lymphocytes, higher count of relative CD4⁺ T lymphocytes, and lower count of absolute CD8⁺ T lymphocytes compared with controls.

CONCLUSION

This pilot study shows higher expression of CD23 on B lymphocytes and on their subsets in patients with AD with and without dupilumab therapy. The higher expression of CD200 on switched B lymphocytes is confirmed only in patients with AD with dupilumab therapy.

Oral Janus kinase inhibitors for atopic dermatitis

Atopic dermatitis (AD) is one of the most common inflammatory skin conditions. The pathogenesis of AD involves skin barrier disruption and immune activation of T-helper (T_H)2 and T_H22 and varying degrees of T_H1 and T_H17 activation in various patient subtypes. Although AD is mainly driven by T_H2, the molecular and clinical heterogeneity of AD underscores the need for more efficacious treatments that target multiple immune axes. Janus kinase (JAK) inhibitors are novel therapeutics that broadly block many AD-related proinflammatory cytokines (interleukin [IL]-4, IL-5, IL-13, IL-31, thymic stromal lymphopoietin, interferon gamma, IL-12, IL-23, IL-17) across different immune pathways. Oral JAK inhibitors have been found to be efficacious in AD, with 2 (abrocitinib and upadacitinib) recently gaining US Food and Drug Administration approval and several others under investigation in clinical trials with promising results. These systemic agents have surpassed conventional thresholds of treatment response, with many patients achieving complete or almost complete skin clearance, and provide a fast-acting alternative therapy for patients who are not responsive to biologics or other conventional therapies. However, systemic JAK inhibitors come with health concerns, requiring additional long-term clinical trials to characterize their safety profile in patients with AD. This review summarizes the current literature on the safety and efficacy of oral JAK inhibitors in AD and discusses future directions for research.

The evolving landscape of biologic therapies for atopic dermatitis: Present and future perspective

Atopic dermatitis (AD) is one of the most common, chronic inflammatory skin diseases with a significant physical, emotional and socioeconomic burden. In recent years the understanding of AD pathogenesis has expanded from the Th2-centred perspective, with the recognition of the involvement of other immune axes. In different AD endotypes, influenced by environment, genetics and race, transcriptomic profiles have identified differing contributions of multiple immune axes such as, Th17, Th22 and Th1. The enriched pathogenic model of AD has catalysed the development of numerous biologic therapies targeting a range of key molecules implicated in disease progression. Currently, dupilumab and tralokinumab, which both target the Th2 pathway, are the only approved biologic therapies for AD in the United States and Europe. New biologic therapies in development, however, target different Th2-pathway molecules along with cytokines in other immune axes, including Th17 and Th22, offering promise for varied treatments for this heterogeneous disease. As the biologic pipeline advances, the integration into clinical practice and approval of these experimental biologics may provide more effective, tailored therapeutic solutions and illuminate on the pathologic processes of AD across a broader, more diverse patient population.

The memory of pathogenic IgE is contained within CD23 + IgG1 + memory B cells poised to switch to IgE in food allergy

Food allergy is caused by allergen-specific IgE antibodies but little is known about the B cell memory of persistent IgE responses. Here we describe in human pediatric peanut allergy CD23 + IgG1 + memory B cells arising in type 2 responses that contain peanut specific clones and generate IgE cells on activation. These 'type2-marked' IgG1 + memory B cells differentially express IL-4/IL-13 regulated genes FCER2 / CD23, IL4R , and germline IGHE and carry highly mutated B cell receptors (BCRs). Further, high affinity memory B cells specific for the main peanut allergen Ara h 2 mapped to the population of 'type2-marked' IgG1 + memory B cells and included convergent BCRs across different individuals. Our findings indicate that CD23 + IgG1 + memory B cells transcribing germline IGHE are a unique memory population containing precursors of pathogenic IgE.

One-Sentence Summary

We describe a unique population of IgG + memory B cells poised to switch to IgE that contains high affinity allergen-specific clones in peanut allergy.

Comparison of the deep immune profiling of B cell subsets between healthy adults and Sjögren's syndrome

OBJECTIVES

Detailed analysis targeting B cell subgroups was considered crucial in monitoring autoimmune diseases and treatment responses. Thus, precisely describing the phenotypes of B cell differentiation and their variation in primary Sjögren's syndrome (pSS) is particularly needed.

METHODS

To characterize the proportions and absolute counts of B cell subsets, peripheral blood from 114 healthy adults of China (age range: 19-73 years) and 55 patients with pSS were performed by flow cytometry and CD19, CD20, CD24, CD27, CD38 and IgD were used as surface markers to identify B cell mature process. Age- and gender-stratified analyses were then carried out to improve the interpretation of B cell subsets.

RESULTS

The assessments from healthy adults showed that the proportion of naive B cells presented a significant increase with age. A reversal trend was noted that the percentage of B10 decreased markedly with age. In addition, analysis based on gender showed that the relative percentage and number of naive B cells were higher in females than in males whereas the proportions of switched memory B cells and B10 cells were decreased in female. Patients with pSS exhibited a significant expansion in naïve B cells and unswitched memory B cells, accompanied with decreased switched memory B cells and B10 cells, which were identified to be associated with autoantibody production.

CONCLUSIONS

Our study presented a reliable analysis by flow cytometry to cover the principal B cell subtypes. These different stages of B lymphocytes may have implications for evaluating the activation of pSS and other autoimmune diseases and treatment efficacy.KEY MESSAGESB cell subsets play a pivotal role in the pathogenesis of primary Sjögren's syndrome (pSS) and other autoimmune diseases. A practical and accurate flow cytometry method to profile B cell phenotypes in peripheral blood of healthy adults is especially essential.Additionally, we presented reliable reference ranges for B cell subsets in regards to the local population. Age- and gender-related analyses are available to better understand their influence in immune status and treatment outcome.The distribution of B-cell subsets is found substantially altered in patients with pSS, bringing novel avenues for pSS research in the future.

Transcriptome-based identification of novel endotypes in adult atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is a frequent and heterogeneous inflammatory skin disease, for which personalized medicine remains a challenge. High-throughput approaches have improved understanding of the complex pathophysiology of AD. However, a purely data-driven AD classification is still lacking.

METHODS

To address this question, we applied an original unsupervised approach on the largest available transcriptome dataset of AD lesional (n = 82) and healthy (n = 213) skin biopsies.

RESULTS

Taking into account pathological and physiological state, a variance-based filtering revealed 222 AD-specific hyper-variable genes that efficiently classified the AD samples into 4 clusters that turned out to be clinically and biologically distinct. Comparison of gene expressions between clusters identified 3 sets of upregulated genes used to derive metagenes (MGs): MG-I (19 genes) was associated with IL-1 family signaling (including IL-36A and 36G) and skin remodeling, MG-II (23 genes) with negative immune regulation (including IL-34 and 37) and skin architecture, and MG-III (17 genes) with B lymphocyte immunity. Sample clusters differed in terms of disease severity (p = .02) and S. aureus (SA) colonization (p = .02). Cluster 1 contained the most severe AD, highest SA colonization, and overexpressed MG-I. Cluster 2 was characterized by less severe AD, low SA colonization, and high MG-II expression. Cluster 3 included mild AD, mild SA colonization, and mild expression of all MGs. Cluster 4 had the same clinical features as cluster 3 but had hyper-expression of MG-III. Last, we successfully validated our method and results in an independent cohort.

CONCLUSION

Our study revealed unrecognized AD endotypes with specific underlying biological pathways, highlighting novel pathophysiological mechanisms. These data could provide new insights into personalized treatment strategies.

Tralokinumab for the Treatment of Atopic Dermatitis

Atopic dermatitis (AD) is a relapsing or chronic heterogeneous inflammatory skin disorder with a substantial economic and social impact. AD is a multifactorial disease regulated by a diverse set of environmental and genetic determinants. The main factors involved in the pathogenesis of AD are epidermal barrier dysfunction, immune dysregulation, and dysbiosis. Current data have valued interleukin (IL)-13 as conceivably the crucial cytokine in the underlying inflammation of AD. Advances in understanding AD pathophysiology have driven the progress of targeted immunomodulatory treatments for the treatment of AD, including tralokinumab, a selective IL-13 inhibitor. A phase IIb clinical trial showed that a dosing regimen of 150 or 300 mg every 2 weeks effectively treated moderate-to-severe AD in adults with an acceptable tolerability profile. Phase III clinical trials demonstrated that results with tralokinumab in monotherapy were superior to those with placebo at 16 weeks of treatment. It was also well tolerated up to 52 weeks in the vast majority of patients. In addition, in association with topical corticosteroids, tralokinumab was well tolerated and effective and had a favorable risk-benefit profile. These data provide additional evidence that IL-13 is central to AD pathogenesis, suggesting that tralokinumab may be seen as an innovative option for the treatment of moderate-to-severe AD.

Increased Th22 cell numbers in a general pediatric population with filaggrin haploinsufficiency: The Generation R Study

BACKGROUND

Mutations in the filaggrin gene (FLG) affect epidermal barrier function and increase the risk of atopic dermatitis (AD). We hypothesized that FLG mutations affect immune cell composition in a general pediatric population. Therefore, we investigated whether school-aged children with and without FLG mutations have differences in T- and B-cell subsets.

METHODS

This study was embedded in a population-based prospective cohort study, the Generation R Study, and included 523 children of European genetic ancestry aged 10 years. The most common FLG mutations in the European population (R501X, S1085CfsX36, R2447X, and S3247X) were genotyped. Additionally, 11-color flow cytometry was performed on peripheral blood samples to determine helper T (Th), regulatory T (Treg), and CD27⁺ and CD27^- memory B cells. Subset analysis was performed in 358 non-AD and 102 AD cases, assessed by parental questionnaires.

RESULTS

FLG mutations were observed in 8.4% of the total population and in 15.7% of the AD cases. Children with any FLG mutation had higher Th22 cell numbers compared to FLG wild-type children in the general and non-AD population. Children with and without FLG mutations had no difference in Th1, Th2, Th17, Treg, or memory B-cell numbers. Furthermore, in children with AD, FLG mutation carriership was not associated with differences in T- and B-cell subsets.

CONCLUSIONS

School-aged children of a general population with FLG mutations have higher Th22 cell numbers, which reflects the immunological response to the skin barrier dysfunction. FLG mutations did not otherwise affect the composition of the adaptive immunity in this general pediatric population.

Use of Tape Strips to Detect Immune and Barrier Abnormalities in the Skin of Children With Early-Onset Atopic Dermatitis

Importance

Molecular profiling of skin biopsies is the criterion standard for evaluating the cutaneous atopic dermatitis (AD) phenotype. However, skin biopsies are not always feasible in children. A reproducible minimally invasive approach that can track cutaneous disease in pediatric longitudinal studies or clinical trials is lacking.

Objective

To assess a minimally invasive approach using tape strips to identify skin biomarkers that may serve as a surrogate to biomarkers identified using whole-tissue biopsies.

Design, Setting, and Participants

This cross-sectional study of 51 children younger than 5 years recruited children with moderate to severe AD and children without AD from the dermatology outpatient clinics at a children's hospital. Sixteen tape strips were serially collected from the nonlesional and lesional skin of 21 children who had AD and were less than 6 months from disease initiation and from the normal skin of 30 children who did not have AD between January 22, 2016, and April 20, 2018.

Main Outcomes and Measures

Gene and protein expression were evaluated using quantitative real-time polymerase chain reaction and immunohistochemistry.

Results

A total of 51 children younger than 5 years were included in the study; 21 children had moderate to severe AD with less than 6 months of disease duration, and 30 children did not have AD. Of the 21 children with AD, the mean (SD) age was 1.7 (1.7) years, and most were male (15 [71.4%] and white (15 [71.4%]). Of the 30 children without AD, the mean (SD) age was 1.8 (2.0) years, and most were female (20 [66.7%]) and white (22 [73.3%]). Seventy-seven of 79 evaluated immune and barrier gene products were detected (gene detection rate, 97%) in 70 of 71 tape strips (sample detection rate, 99%), with 53 of 79 markers differentiating between children with lesional and/or nonlesional AD from children without AD. Many cellular markers of T cells (CD3), AD-related dendritic cells (Fc ε RI and OX40 ligand receptors), and key inflammatory (matrix metallopeptidase 12), innate (interleukin 8 [IL-8] and IL-6), helper T cell 2 (TH2; IL-4, IL-13, and chemokines CCL17 and CCL26), and TH17/TH22 (IL-19, IL-36G, and S100A proteins) genes were significantly increased in lesional and nonlesional AD compared with tape strips from normal skin. For example, IL-4 mean (SE) for lesional was -15.2 (0.91) and normal was -19.5 (0.48); P < .001. Parallel decreases occurred in epidermal barrier gene products (FLG, CLDN23, and FA2H) and negative immune regulators (IL-34 and IL-37). For example, the decrease for FLG lesional was mean (SE) -2.9 (0.42) and for normal was 2.2 (0.45); P < .001. Associations were found between disease severity or transepidermal water loss and TH2 (IL-33 and IL-4R) and TH17/TH22 (IL-36G and S100As) products in lesional and nonlesional AD skin (evaluated using the SCORing Atopic Dermatitis, Eczema Area and Severity Index, and Pruritus Atopic Dermatitis Quickscore tools).

Conclusions and Relevance

In this study, tape strips provide a minimally invasive alternative for serially evaluating AD-associated cutaneous biomarkers and may prove useful for tracking pediatric AD therapeutic response and predicting future course and comorbidities.

Tfh Cells in Health and Immunity: Potential Targets for Systems Biology Approaches to Vaccination

T follicular helper (Tfh) cells are a specialised subset of CD4+ T cells that play a significant role in the adaptive immune response, providing critical help to B cells within the germinal centres (GC) of secondary lymphoid organs. The B cell receptors of GC B cells undergo multiple rounds of somatic hypermutation and affinity maturation within the GC response, a process dependent on cognate interactions with Tfh cells. B cells that receive sufficient help from Tfh cells form antibody-producing long-lived plasma and memory B cells that provide the basis of decades of effective and efficient protection and are considered the gold standard in correlates of protection post-vaccination. However, the T cell response to vaccination has been understudied, and over the last 10 years, exponential improvements in the technological underpinnings of sampling techniques, experimental and analytical tools have allowed multidisciplinary characterisation of the role of T cells and the immune system as a whole. Of particular interest to the field of vaccinology are GCs and Tfh cells, representing a unique target for improving immunisation strategies. Here, we discuss recent insights into the unique journey of Tfh cells from thymus to lymph node during differentiation and their role in the production of high-quality antibody responses as well as their journey back to the periphery as a population of memory cells. Further, we explore their function in health and disease and the power of next-generation sequencing techniques to uncover their potential as modulators of vaccine-induced immunity.

CD23 expression on switched memory B cells bridges T-B cell interaction in allergic rhinitis

BACKGROUND

The contribution of B-cell subsets and T-B cell interaction to the pathogenesis of allergic rhinitis (AR) and mechanisms of allergen immunotherapy (AIT) remain poorly understood. This study aimed to outline circulating B-cell signature, the underlying mechanism, and its association with clinical response to AIT in patients with AR.

METHODS

IgD/CD27 and CD24/CD38 core gating systems were used to determine frequencies and phenotypes of B cells. Correlations between B cells, T cells, antigen-specific IgE, and disease severity in AR patients were investigated. Switched memory B cells were co-cultured with type 2 follicular helper T (Tfh2) cells and follicular regulatory T (Tfr) cells. Associations between B-cell subsets and clinical benefits of AIT were analyzed.

RESULTS

Frequencies and absolute numbers of circulating memory B cells were increased in AR patients. CD23 expression on CD19⁺ CD20⁺ CD27⁺ IgD^- switched memory B cells was significantly enhanced and positively correlated with antigen-specific IgE levels, symptom scores, and Tfh2/Tfr cell ratio in AR patients. Compared with those from healthy controls, Tfh2 cells from AR patients had a greater capacity to induce CD23 expression on switched memory B cells via IL-4, which was unable to be sufficiently suppressed by AR-associated Tfr cells with defective IL-10 expression. CD23 expression on switched memory B cells was downregulated after 12-month AIT, which positively associated with disease remission in AR patients.

CONCLUSION

T-B cell interaction, bridged by CD23 expression particularly on switched memory B cells, may be involved in the disease pathogenesis and mechanism of AIT in patients with AR.

Role of B cells in immune-mediated dermatoses

Although T cells are considered as the central component in immune-mediated diseases, supportive evidence has demonstrated that B cells also contribute to the progression of these diseases. B cells are divided into various subsets according to their secreted cytokines. Different B cell subsets play diverse roles in immune-mediated dermatoses. Regulatory B cells (Bregs) are defined functionally by their ability to secrete IL-10, which has been revealed to contribute to immunological tolerance. Drugs that deplete B cells, such as rituximab, are now used for the treatment of several immune-mediated dermatoses. In this review, we present and discuss the current knowledge on the roles of B cells in several immune-mediate dermatoses including psoriasis, pemphigus, bullous pemphigoid, and dermatomyositis, atopic dermatitis.

Treatments for Childhood Atopic Dermatitis: an Update on Emerging Therapies

Atopic dermatitis (AD) is generally considered a T helper type 2-dominated disease. Pediatric AD is usually less severe than adult AD, but it may present as moderate to severe lesions that are inadequately managed by current modalities including emollients/moisturizers, topical corticosteroids (TCSs), topical calcineurin inhibitors (TCIs), and even systemic immunosuppressants (such as cyclosporine, azathioprine, methotrexate, and mycophenolate mofetil). In addition, systemic immunosuppressants are often not recommended for childhood AD by the current guidelines due to their toxicities. Therefore, there is still an unmet need for a safe and effective long-term therapy for pediatric AD patients whose disease is inadequately controlled or who are intolerant to current treatments. The emerging therapeutics for AD focuses on intervening in the inflammatory pathway by targeting specific cytokines/chemokines or their receptors. Monoclonal antibodies against immunoglobulin E (IgE), interleukin (IL)-4 receptor subunit α, IL-5, IL-13, IL-31 receptor subunit α, IL-33, and thymic stromal lymphopoietin (TSLP) have been evaluated clinically for AD. Encouraging results have been reported for many of the biologics, of which the most exciting is dupilumab. Other emerging systemic therapies include small molecules such as baricitinib, abrocitinib, upadacitinib, and tradipitant. Several novel topical agents are under clinical investigation for the treatment of AD, including topical phosphodiesterase 4 (PDE4) inhibitors, Janus kinase (JAK) inhibitors, aryl hydrocarbon receptor (AhR) modulating agents, and transient receptor potential vanilloid subfamily member 1 (TRPV1) antagonists. Accompanied by thorough characterization of different phenotype and endotype subsets, the application of precision medicine could provide new prospects for the optimal treatment of AD.

Elevated circulating Th2 but not group 2 innate lymphoid cell responses characterize canine atopic dermatitis

Atopic dermatitis (AD) is an allergic skin disease that causes significant morbidity and affects multiple species. AD is highly prevalent in companion dogs, and the clinical management of the disease remains challenging. An improved understanding of the immunologic and genetic pathways that lead to disease could inform the development of novel treatments. In allergic humans and mouse models of AD, the disease is associated with Th2 and group 2 innate lymphoid cell (ILC2) activation that drives type 2 inflammation. Type 2 inflammation also appears to be associated with AD in dogs, but gaps remain in our understanding of how key type 2-associated cell types such as canine Th2 cells and ILC2s contribute to the pathogenesis of canine AD. Here, we describe previously uncharacterized canine ILC2-like cells and Th2 cells ex vivo that produced type 2 cytokines and expressed the transcription factor Gata3. Increased circulating Th2 cells were associated with chronic canine AD. Single-cell RNA sequencing revealed a unique gene expression signature in T cells in dogs with AD. These findings underline the importance of pro-allergic Th2 cells in orchestrating AD and provide new methods and pathways that can inform the development of improved therapies.

New treatments for atopic dermatitis targeting beyond IL-4/IL-13 cytokines

OBJECTIVE

Atopic dermatitis (AD) is an increasingly common inflammatory skin disease undergoing significant revolution in recent years. New data on disease pathogenesis advanced the developments of novel therapeutics, mainly for patients with moderate to severe conditions, for whom treatment options have been largely insufficient for many years.

DATA SOURCES

Review of recent studies investigating systemic treatments for AD.

STUDY SELECTIONS

Relevant literature concerning novel therapeutics for AD beyond targeted monoclonal antibodies antagonizing selectively interleukin (IL)-4 or IL-13 was obtained from a PubMed and clinicaltrials.gov search and summarized.

RESULTS

Multiple clinical trials of both nonspecific as well as specific agents revealed favorable outcomes in AD, including JAK inhibitors, a dual JAK/SYK inhibitor, a histamine H4R antagonist, antagonists of the TSLP/OX40L axis, an IL-22 inhibitor, and IL-33 and IL-17C antagonists. Importantly, negative trials were published as well (eg, phosphodiesterase 4 inhibitor, apremilast).

CONCLUSION

In this rapidly evolving field of AD treatments, a completely new treatment paradigm will be available in the near future.

The IL-13-OVOL1-FLG axis in atopic dermatitis

Despite sharing interleukin-4 receptor α (IL-4Rα) in their signaling cascades, IL-4 and IL-13 have different functions in atopic inflammation. IL-13 preferentially participates in the peripheral tissues because tissue-resident group 2 innate lymphoid cells produce IL-13 but not IL-4. In contrast, lymph node T follicular helper cells express IL-4 but not IL-13 to regulate B-cell immunity. The dominant microenvironment of IL-13 is evident in the lesional skin of atopic dermatitis (AD). The IL-13-rich local milieu causes barrier dysfunction by down-regulating the OVOL1-filaggrin (FLG) axis and up-regulating the periostin-IL-24 axis. Genome-wide association studies also point to the crucial involvement of the IL-13, OVOL1 and FLG genes in the pathogenesis of AD. Biologics targeting IL-13, such as the anti-IL-4Rα antibody dupilumab and the anti-IL-13 antibody tralokinumab, successfully improve AD lesions and further highlight the importance of IL-13 in the pathogenesis of AD.

The oral Janus kinase/spleen tyrosine kinase inhibitor ASN002 demonstrates efficacy and improves associated systemic inflammation in patients with moderate-to-severe atopic dermatitis: results from a randomized double-blind placebo-controlled study

BACKGROUND

ASN002 is an oral dual inhibitor of Janus kinase and spleen tyrosine kinase, which are involved in the pathogenesis of atopic dermatitis (AD) through their regulatory role on T helper (Th)1, Th2 and Th17/Th22 pathways.

OBJECTIVES

The objectives of this study were to evaluate the efficacy, safety, pharmacokinetics and effects on systemic biomarkers of ASN002 in patients with moderate-to-severe AD. Methods A total of 36 patients with moderate-to-severe AD were randomized (3 : 1) to ASN002 or placebo in the phase Ib study. Three dosage cohorts were studied over a 28-day period (20 mg, 40 mg and 80 mg once daily).

RESULTS

ASN002 was superior to placebo for the proportion of patients achieving Eczema Area and Severity Index (EASI) 50 (20 mg 20%, P = 0·93; 40 mg 100%, P = 0·003; 80 mg 83%, P = 0·03; placebo 22%), EASI 75 (20 mg 0%, P = 0·27; 40 mg 71%, P = 0·06; 80 mg 33%, P = 0·65; placebo 22%) and in change from baseline in pruritus (20 mg -1·3 ± 2·1, P = 0·81; 40 mg -3·1 ± 2·7, P = 0·27; 80 mg -4·7 ± 2·1, P = 0·01; placebo -1·6 ± 1·8). Adverse events were generally mild and similar across all groups. ASN002 showed dose-dependent plasma exposure with low interpatient variability, significantly downregulated several serum biomarkers involved in Th1, Th2 and Th17/Th22 immunity, and decreased the atherosclerosis-associated biomarker E selectin/SELE.

CONCLUSIONS

In patients with moderate-to-severe AD, ASN002 showed strong efficacy with rapid onset of action and associated improvements in systemic inflammation.

The skin as an immune organ: Tolerance versus effector responses and applications to food allergy and hypersensitivity reactions

Skin is replete with immunocompetent cells that modulate signaling pathways to maintain a salubrious immunogenic/tolerogenic balance. This fertile immune environment plays a significant role in the development of allergic responses and sensitivities, but the mechanisms underlying these pathways have been underappreciated and underused with respect to developing therapeutics. Among the complex repertoire of cells that promote tolerogenic pathways in the periphery, 2 key classes include dendritic cells and regulatory T (Treg) cells. Immature dendritic cells are the first line of defense, patrolling the periphery, sampling antigens, and secreting cytokines that suppress immune cells and promote the survival of Treg cells. Skin-homing Treg cells also play a critical role in mitigating the reactivity of immune cells, secreting high levels of cytokines that promote tolerance. Therapeutic approaches that capitalize on our knowledge of the rich cellular and molecular environment are emerging and show great promise. We will discuss the advantages and challenges of 5 such strategies and how these therapies might mitigate the atopic march by facilitating tolerance. We conclude that skin is a multifaceted structure that provides a fertile ground for therapeutic discovery. Accordingly, ongoing work in this domain will no doubt continue to deliver exciting progress for improved health outcomes.

Early immunologic changes during the onset of atopic dermatitis

OBJECTIVE

Atopic dermatitis (AD), which is commonly called eczema, is the most common chronic inflammatory skin disease. The pipeline of new targeted treatments is currently expanding, a development that is largely based on our increasing understanding of disease mechanisms. Mechanistic insights have long been based on long-standing adult AD. Recently, studies also investigated early pediatric AD at disease onset, and revealed several differences in barrier and immune properties when compared with long-standing adult AD. This review focuses on immunological changes very early in life that predispose to the development of AD, and summarizes characteristics of the molecular AD phenotype in this age group.

DATA SOURCES

Review of published literature.

STUDY SELECTIONS

Studies investigating human AD at disease onset in newborns, toddlers, and young children, in comparison with adults with long-standing disease.

RESULTS

Already in cord blood, increased Th2 and decreased Th1 levels were found to increase the risk of AD development. Both pediatric and adult AD share Th2/Th22 activation and defects in lipid barrier deposition and tight junction formation, but Th1 activation and epidermal differentiation complex defects are largely absent in pediatric AD.

CONCLUSION

Immune changes predisposing to AD development are present very early in life. During the first months of disease, AD shows various differences in immune and barrier properties from long-standing adult AD, which might necessitate tailored treatment approaches depending on the age of the patient.

Topical agents for the treatment of atopic dermatitis

INTRODUCTION

Atopic dermatitis (AD) is perhaps the most common inflammatory skin disorder worldwide, with an increasing incidence in developed countries. The mainstay treatment for patients with AD is topical therapies, which are used not only by the mild patients but also by the moderate-to-severe patients, in conjunction with systemic treatment. While topical steroids and calcineurin antagonists are widely used, these are associated with long-term cutaneous adverse effects (AEs) or a black box warning, preventing their chronic use. Areas covered: The aim of this review is to provide a comprehensive overview of new and upcoming topical therapies currently in development and undergoing clinical trials, as well as their safety and efficacy profiles, and discuss current topicals used in the management of AD. Expert opinion: AD is a heterogeneous disease with complex pathophysiology. Treatments available to date for AD provide disease control; however, patients struggle to find an optimized therapeutic regimen they may use long term and without severe effects. Novel therapies are currently under investigation, with the hope of shifting the paradigm of AD management from symptom control to disease eradication.

Atopic dermatitis yardstick: Practical recommendations for an evolving therapeutic landscape

The implementation of treatment guidelines for atopic dermatitis is challenging, in part because of different guidance documents being used by different groups of specialists and in part because the language of guidelines often reflects the evidence base rather than the practical "how to." The Atopic Dermatitis Yardstick is part of a series developed in response to the need to proactively address the loss of disease control for atopic illnesses at all levels of severity. It presents a comprehensive update on how to conduct a sustained step-up in therapy for the patient with inadequately controlled or poorly controlled atopic dermatitis. Patient profiles, based on current guidelines and the authors' combined clinical experience, provide a practical and clinically meaningful guide to aid physicians in helping their patients achieve the goal of clear to almost clear. The intent is not to replace guidelines but to complement their recommendations incorporating the latest research and therapies.

Distinct transcriptomic profiles of early-onset atopic dermatitis in blood and skin of pediatric patients

BACKGROUND

Atopic dermatitis (AD) predominantly affects young children, but our understanding of AD pathogenesis is based on skin and blood samples from long-standing adult AD. Genomic biopsy profiling from early pediatric AD showed significant Th2 and Th17/Th22-skewing, without the characteristic adult Th1 up-regulation. Because obtaining pediatric biopsies is difficult, blood gene expression profiling may provide a surrogate for the pediatric skin signature.

OBJECTIVE

To define the blood profile and associated biomarkers of early moderate-to-severe pediatric AD.

METHODS

We compared microarrays and reverse transcription polymerase chain reaction (RT-PCR) of blood cells from 28 AD children (<5 years and within 6 months of disease onset) to healthy control blood cells. Differentially expressed genes (DEGs) in blood (fold change [FCH] > 1.2 and false discovery rate [FDR] < 0.05) were then compared with skin DEGs.

RESULTS

Eosinophil and Th2 markers (IL5RA, IL1RL1/ST2, HRH4, CCR3, SIGLEC8, PRSS33, CLC from gene arrays; IL13/IL4/CCL22 from RT-PCR) were up-regulated in early pediatric AD blood, whereas IFNG/Th1 was decreased. Th1 markers were negatively correlated with clinical severity (EASI, pruritus, transepidermal water loss [TEWL]), whereas Th2/Th17-induced interleukin (IL)-19 was positively correlated with SCORAD. Although a few RT-PCR-defined immune markers (IL-13/CCL22) were increased in blood, as previously also reported for skin, minimal overlap based on gene array DEGs was seen.

CONCLUSION

The whole blood signature of early moderate-to-severe pediatric AD blood cells show predominantly a Th2/eosinophil profile; however, markers largely differ from the skin profile. Given their complementarity, pooling of biomarkers from blood and skin may improve profiling and predictions, providing insight regarding disease course, allergic comorbidity development, and response to systemic medications.

Advances in atopic dermatitis in 2017

This review encompasses relevant scientific and clinical advances in atopic dermatitis (AD) published in 2017. These include articles from the Journal of Allergy and Clinical Immunology, as well as other prominent publications that have contributed to the emerging field, on the microenvironment of the skin and molecular patterns guiding biologic treatment strategies. The most commonly questioned and explored themes of the year included the effect of the microbiome on AD development, as well as cell signaling and symptom severity. Topics also included the description of patient-specific molecular endotypes within the larger population with AD. All of these factors will create potential opportunities to guide personalized therapy with the broadening array of topical and systemic interventions currently available, as well as providing new insights to guide the development of novel molecularly targeted therapeutics. With recent US Food and Drug Administration approval of the first wave of new targeted therapies for AD, additional information exploring the safety profiles and long-term effects of these medications was also at the forefront in 2017.

Recent Developments in Atopic Dermatitis

Atopic dermatitis (AD) is a bothersome and common skin disease affecting ∼10.7% of children in the United States. This skin condition significantly decreases quality of life in not only patients, but in their families as well. Pediatricians are often the first physicians to diagnose and manage these patients and thus are relied on by families to answer questions about this disease. AD is complex, multifactorial, and has historically had limited therapeutic options, but the landscape of this disease is now rapidly changing. Pathways contributing to the pathogenesis of this disease are continually being discovered, and new therapies for AD are being developed at an unprecedented rate. With this article, we will review the current guidelines regarding the management of AD, outline updates in the current understanding of its pathophysiology, and highlight novel developments available for the treatment of this burdensome disease.

Testing biologics and intracellular signaling inhibitors on pediatric atopic dermatitis: a stairway to modern therapeutic approaches

INTRODUCTION

Atopic dermatitis (AD) is the most common cutaneous inflammatory disease in adults and children. In the last few years, the pathogenesis of AD has been profoundly revised, and this has led to the identification of novel druggable targets and the development of new agents targeting specific molecular pathways. Despite the high prevalence of AD in the pediatric population, the clinical development of new treatments, either topical or systemic, has been focused on the adult population in recent years; only a limited number of these new agents have been tested in pediatric cohorts.

AREAS COVERED

In this review, we describe the pathogenic model of pediatric AD which shows similarities and substantial differences when compared to adult AD. The identification of therapeutic targets is highlighted, and novel targeted therapies, both topical and systemic, are discussed.

EXPERT OPINION

The current therapeutic armamentarium for pediatric AD is very limited, and this represents a critical unmet need. The enhancement of clinical research on pediatric patients is necessary to facilitate an increase in the number of new targeted therapeutic options being available on the market.

Insights Into the Molecular Mechanisms of T Follicular Helper-Mediated Immunity and Pathology

T follicular helper (Tfh) cells play key role in providing help to B cells during germinal center (GC) reactions. Generation of protective antibodies against various infections is an important aspect of Tfh-mediated immune responses and the dysregulation of Tfh cell responses has been implicated in various autoimmune disorders, inflammation, and malignancy. Thus, their differentiation and maintenance must be closely regulated to ensure appropriate help to B cells. The generation and function of Tfh cells is regulated by multiple checkpoints including their early priming stage in T zones and throughout the effector stage of differentiation in GCs. Signaling pathways activated downstream of cytokine and costimulatory receptors as well as consequent activation of subset-specific transcriptional factors are essential steps for Tfh cell generation. Thus, understanding the mechanisms underlying Tfh cell-mediated immunity and pathology will bring into spotlight potential targets for novel therapies. In this review, we discuss the recent findings related to the molecular mechanisms of Tfh cell differentiation and their role in normal immune responses and antibody-mediated diseases.

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.

Allergic disease in 8-year-old children is preceded by delayed B cell maturation

BACKGROUND

We previously reported that exposure to a farming environment is allergy-protective, while high proportions of neonatal immature/naïve CD5⁺ B cells and putative regulatory T cells (Tregs) are risk factors for development of allergic disease and sensitization up to 3 years of age.

OBJECTIVE

To examine if B and T cell maturation are associated with allergic disease and farming environment over the first 8 years in life.

METHODS

In the prospective FARMFLORA study, including both farming and non-farming families, 48 of 65 children took part in the 8-year follow-up study. Various B and T cell maturation variables were examined in blood samples obtained at several occasions from birth to 8 years of age and related to doctors' diagnosed allergic disease and sensitization, and to farming environment.

RESULTS

We found that the incidence of allergic disease was lower among farmers' compared to non-farmers' children during the 8-year follow-up period, and that farmers' children had higher proportions of memory B cells at 8 years of age. Moreover, a high proportion of neonatal CD5⁺ B cells was a risk factor for and may predict development of allergic disease at 8 years of age. A high proportion of Tregs was not protective against development of these conditions.

CONCLUSION AND CLINICAL RELEVANCE

High proportions of neonatal naïve B cells remained as a risk factor for allergic disease in school-aged children. Thus, the accelerated B cell maturation observed among farmers' children may be crucial for the allergy-protective effect of a farming environment.