Atopic dermatitis (AD) is the most common chronic skin inflammatory disease, with a profound impact on patients’ quality of life. AD varies considerably in clinical course, age of onset and degree to ...which it is accompanied by allergic and non-allergic comorbidities. Skin barrier impairment in both lesional and nonlesional skin is now recognized as a critical and often early feature of AD. This may be explained by a number of abnormalities identified within both the stratum corneum and stratum granulosum layers of the epidermis. The goal of this review is to provide an overview of key barrier defects in AD, starting with a historical perspective. We will also highlight some of the commonly used methods to characterize and quantify skin barrier function. There is ample opportunity for further investigative work which we call out throughout this review. These include: quantifying the relative impact of individual epidermal abnormalities and putting this in a more holistic view with physiological measures of barrier function, as well as determining whether these barrier-specific endotypes predict clinical phenotypes (e.g. age of onset, natural history, comorbidities, response to therapies, etc). Mechanistic studies with new (and in development) AD therapies that specifically target immune pathways, Staphylococcus aureus abundance and/or skin barrier will help us understand the dynamic crosstalk between these compartments and their relative importance in AD.
For at least half a century, noninvasive techniques have been available to quantify skin barrier function, and these have shown that a number of human skin conditions and disorders are associated ...with defects in skin permeability. In the past decade, several genes responsible for skin barrier defects observed in both monogenetic and complex polygenic disorders have been elucidated and functionally characterized. This has led to an explosion of work in the past 6 years that has identified pathways connecting epidermal barrier disruption and antigen uptake, as well as the quality and/or magnitude of the antigen-specific adaptive immune response. This review will introduce the notion that diseases arise from the dynamic crosstalk that occurs between skin barrier and the immune system using atopic dermatitis or eczema as the disease prototype. Nevertheless, the concepts put forth are highly relevant to a number of antigen-driven disorders for which skin barrier is at least transiently compromised, such as psoriasis, allergic contact dermatitis, and blistering disorders.
Orchestrating when and how the cutaneous innate immune system should respond to commensal or pathogenic microbes is a critical function of the epithelium. The cutaneous innate immune system is a key ...determinant of the physical, chemical, microbial, and immunologic barrier functions of the epidermis. A malfunction in this system can lead to an inadequate host response to a pathogen or a persistent inflammatory state. Atopic dermatitis is the most common inflammatory skin disorder and characterized by abnormalities in both skin barrier structures (stratum corneum and tight junctions), a robust TH 2 response to environmental antigens, defects in innate immunity, and an altered microbiome. Many of these abnormalities may occur as the consequence of epidermal dysfunction. The epidermis directly interfaces with the environment and, not surprisingly, expresses many pattern recognition receptors that make it a key player in cutaneous innate immune responses to skin infections and injury. This review will discuss the role epidermal innate receptors play in regulation of skin barriers and, where possible, discuss the relevance of these findings for patients with atopic dermatitis.
Summary Background Data from early-stage studies suggested that interleukin (IL)-4 and IL-13 are requisite drivers of atopic dermatitis, evidenced by marked improvement after treatment with ...dupilumab, a fully-human monoclonal antibody that blocks both pathways. We aimed to assess the efficacy and safety of several dose regimens of dupilumab in adults with moderate-to-severe atopic dermatitis inadequately controlled by topical treatments. Methods In this randomised, placebo-controlled, double-blind study, we enrolled patients aged 18 years or older who had an Eczema Area and Severity Index (EASI) score of 12 or higher at screening (≥16 at baseline) and inadequate response to topical treatments from 91 study centres, including hospitals, clinics, and academic institutions, in Canada, Czech Republic, Germany, Hungary, Japan, Poland, and the USA. Patients were randomly assigned (1:1:1:1:1:1), stratified by severity (moderate or severe, as assessed by Investigator's Global Assessment) and region (Japan vs rest of world) to receive subcutaneous dupilumab: 300 mg once a week, 300 mg every 2 weeks, 200 mg every 2 weeks, 300 mg every 4 weeks, 100 mg every 4 weeks, or placebo once a week for 16 weeks. We used a central randomisation scheme, provided by an interactive voice response system. Drug kits were coded, providing masking to treatment assignment, and allocation was concealed. Patients on treatment every 2 weeks and every 4 weeks received volume-matched placebo every week when dupilumab was not given to ensure double blinding. The primary outcome was efficacy of dupilumab dose regimens based on EASI score least-squares mean percentage change (SE) from baseline to week 16. Analyses included all randomly assigned patients who received one or more doses of study drug. This trial is registered with ClinicalTrials.gov , number NCT01859988. Findings Between May 15, 2013, and Jan 27, 2014, 452 patients were assessed for eligibility, and 380 patients were randomly assigned. 379 patients received one or more doses of study drug (300 mg once a week n=63, 300 mg every 2 weeks n=64, 200 mg every 2 weeks n=61, 300 mg every 4 weeks n=65, 100 mg every 4 weeks n=65; placebo n=61). EASI score improvements favoured all dupilumab regimens versus placebo (p<0·0001): 300 mg once a week (−74% SE 5·16), 300 mg every 2 weeks (−68% 5·12), 200 mg every 2 weeks (−65% 5·19), 300 mg every 4 weeks (−64% 4·94), 100 mg every 4 weeks (−45% 4·99); placebo (−18% 5·20). 258 (81%) of 318 patients given dupilumab and 49 (80%) of 61 patients given placebo reported treatment-emergent adverse events; nasopharyngitis was the most frequent (28% and 26%, respectively). Interpretation Dupilumab improved clinical responses in adults with moderate-to-severe atopic dermatitis in a dose-dependent manner, without significant safety concerns. Our findings show that IL-4 and IL-13 are key drivers of atopic dermatitis. Funding Sanofi and Regeneron Pharmaceuticals.
Background
Patients with moderate-to-severe atopic dermatitis (AD) have increased infection risk, including skin infections and systemic infections. Immunomodulators (e.g., anti-tumor necrosis ...factors, anti-interleukin anti-IL-23, anti-IL-17, Janus kinase inhibitors) increase risk of infections. Dupilumab (a monoclonal antibody blocking the shared receptor component for IL-4 and IL-13) is approved for inadequately controlled moderate-to-severe AD and for moderate-to-severe eosinophilic or oral corticosteroid-dependent asthma.
Objective
The aim was to determine the impact of dupilumab on infection rates in patients with moderate-to-severe AD.
Methods
This analysis pooled data from seven randomized, placebo-controlled dupilumab trials in adults with moderate-to-severe AD. Exposure-adjusted analyses assessed infection rates.
Results
Of 2932 patients, 1091 received placebo, 1095 dupilumab 300 mg weekly, and 746 dupilumab 300 mg every 2 weeks. Treatment groups had similar infection rates overall per 100 patient-years (placebo, 155; dupilumab weekly, 150; dupilumab every 2 weeks, 156; dupilumab combined, 152), and similar non-skin infection rates. Serious/severe infections were reduced with dupilumab (risk ratio 0.43;
p
< 0.05), as were bacterial and other non-herpetic skin infections (risk ratio 0.44;
p
< 0.001). Although herpesviral infection rates overall were slightly higher with dupilumab than placebo, clinically important herpesviral infections (eczema herpeticum, herpes zoster) were less common with dupilumab (risk ratio 0.31;
p
< 0.01). Systemic anti-infective medication use was lower with dupilumab.
Conclusions
Dupilumab is associated with reduced risk of serious/severe infections and non-herpetic skin infections and does not increase overall infection rates versus placebo in patients with moderate-to-severe AD.
ClinicalTrials.gov Identifiers
NCT01548404, NCT02210780, NCT01859988, NCT02277743, NCT02277769, NCT02260986, and NCT02755649.
Background Atopic dermatitis (AD) is a chronic inflammatory skin disease that is characterized by a defective skin barrier function. Recent studies have reported mutations of the skin barrier gene ...encoding filaggrin in a subset of patients with AD. Objective We investigated whether reduced filaggrin expression was found in patients with AD who were not carriers of known filaggrin mutations and whether filaggrin expression was modulated by the atopic inflammatory response. Methods Filaggrin expression was measured in skin biopsies and cultured keratinocytes using real-time RT-PCR and immunohistochemistry. Filaggrin loss-of-function mutations were screened in a total of 69 subjects. Results Compared with normal skin, filaggrin expression was significantly reduced ( P < .05) in acute AD skin, with further reduction seen in acute lesions from 3 European American subjects with AD who were heterozygous for the 2282del4 mutation. This was confirmed by using immunohistochemistry. AD skin is characterized by the overexpression of IL-4 and IL-13. Keratinocytes differentiated in the presence of IL-4 and IL-13 exhibited significantly reduced filaggrin gene expression (0.04 ± 0.01 ng filaggrin/ng glyceraldehyde 3-phosphate dehydrogenase; P < .05) compared with media alone (0.16 ± 0.03). Conclusion Patients with AD have an acquired defect in filaggrin expression that can be modulated by the atopic inflammatory response. Clinical implications The atopic immune response contributes to the skin barrier defect in AD; therefore, neutralization of IL-4 and IL-13 could improve skin barrier integrity.
Atopic dermatitis is a chronic inflammatory skin disease characterized by pruritic skin lesions.
We sought to evaluate the safety and efficacy of multiple doses of the selective Janus kinase 1 ...inhibitor upadacitinib in patients with moderate to severe atopic dermatitis.
In the 16-week, double-blind, placebo-controlled, parallel-group, dose-ranging portion of this 88-week trial in 8 countries (ClinicalTrials.gov, NCT02925117; ongoing, not recruiting), adults with moderate to severe disease and inadequate control by topical treatment were randomized 1:1:1:1, using an interactive response system and stratified geographically, to once-daily upadacitinib oral monotherapy 7.5, 15, or 30 mg or placebo. The primary end point was percentage improvement in Eczema Area and Severity Index from baseline at week 16. Efficacy was analyzed by intention-to-treat in all randomized patients. Safety was analyzed in all randomized patients who received study medication, based on actual treatment.
Patients (N = 167) enrolled from November 21, 2016, to April 20, 2017. All were randomized and analyzed for efficacy (each upadacitinib group, n = 42; placebo, n = 41); 166 were analyzed for safety (each upadacitinib group, n = 42; placebo, n = 40). The mean (SE) primary efficacy end point was 39% (6.2%), 62% (6.1%), and 74% (6.1%) for the upadacitinib 7.5-, 15-, and 30-mg groups, respectively, versus 23% (6.4%) for placebo (P = .03, <.001, and <.001). Serious adverse events occurred in 4.8% (2 of 42), 2.4% (1 of 42), and 0% (0 of 42) of upadacitinib groups (vs 2.5% 1 of 40 for placebo).
A dose-response relationship was observed for upadacitinib efficacy; the 30-mg once-daily dose showed the greatest clinical benefit. Dose-limiting toxicity was not observed.
Skin barrier dysfunction, a defining feature of atopic dermatitis (AD), arises from multiple interacting systems. In AD, skin inflammation is caused by host–environment interactions involving ...keratinocytes as well as tissue-resident immune cells such as type 2 innate lymphoid cells, basophils, mast cells, and T helper type 2 cells, which produce type 2 cytokines, including IL-4, IL-5, IL-13, and IL-31. Type 2 inflammation broadly impacts the expression of genes relevant for barrier function, such as intracellular structural proteins, extracellular lipids, and junctional proteins, and enhances Staphylococcus aureus skin colonization. Systemic anti‒type 2 inflammation therapies may improve dysfunctional skin barrier in AD.
Background Atopic dermatitis (AD) is a chronic inflammatory skin disease that is characterized by a defective skin barrier function. Recent studies have reported mutations of the skin barrier gene ...encoding filaggrin in a subset of patients with AD. Objective We investigated whether reduced filaggrin expression was found in patients with AD who were not carriers of known filaggrin mutations and whether filaggrin expression was modulated by the atopic inflammatory response. Methods Filaggrin expression was measured in skin biopsies and cultured keratinocytes using real-time RT-PCR and immunohistochemistry. Filaggrin loss-of-function mutations were screened in a total of 69 subjects. Results Compared with normal skin, filaggrin expression was significantly reduced ( P < .05) in acute AD skin, with further reduction seen in acute lesions from 3 European American subjects with AD who were heterozygous for the 2282del4 mutation. This was confirmed by using immunohistochemistry. AD skin is characterized by the overexpression of IL-4 and IL-13. Keratinocytes differentiated in the presence of IL-4 and IL-13 exhibited significantly reduced filaggrin gene expression (0.04 ± 0.01 ng filaggrin/ng glyceraldehyde 3-phosphate dehydrogenase; P < .05) compared with media alone (0.16 ± 0.03). Conclusion Patients with AD have an acquired defect in filaggrin expression that can be modulated by the atopic inflammatory response. Clinical implications The atopic immune response contributes to the skin barrier defect in AD; therefore, neutralization of IL-4 and IL-13 could improve skin barrier integrity.
Atopic dermatitis (AD) affects up to 20% of children worldwide and is an increasing public health problem, particularly in developed countries. Although AD in infants and young children can resolve, ...there is a well-recognized increased risk of sequential progression from AD to other atopic diseases, including food allergy (FA), allergic rhinitis, allergic asthma, and allergic rhinoconjunctivitis, a process referred to as the atopic march. The mechanisms underlying the development of AD and subsequent progression to other atopic comorbidities, particularly FA, are incompletely understood and the subject of intense investigation. Other major research objectives are the development of effective strategies to prevent AD and FA, as well as therapeutic interventions to inhibit the atopic march. In 2017, the Division of Allergy, Immunology, and Transplantation of the National Institute of Allergy and Infectious Diseases sponsored a workshop to discuss current understanding and important advances in these research areas and to identify gaps in knowledge and future research directions. International and national experts in the field were joined by representatives from several National Institutes of Health institutes. Summaries of workshop presentations, key conclusions, and recommendations are presented herein.
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