New concept of the pathogenesis of atopic dermatitis: Interplay among the barrier, allergy, and pruritus as a trinity

Phase 1 studies to assess the safety, tolerability and pharmacokinetics of JTE-052 (a novel Janus kinase inhibitor) ointment in Japanese healthy volunteers and patients with atopic dermatitis

The purpose of the present two phase 1 studies was to assess the safety, tolerability and pharmacokinetics for topical application of a novel Janus kinase (JAK) inhibitor, JTE‐052, in Japanese healthy adult male volunteers and Japanese adult patients with atopic dermatitis (AD). Additionally, exploratory investigation was performed on the efficacy for disease severity and pruritus score in AD patients. In the QBX1‐1 study, the cutaneous safety of JTE‐052 ointment by a patch test and a photo patch test was assessed in an intra‐individual comparative study using placebo ointment, white petrolatum and non‐application as comparators. The study demonstrated that JTE‐052 ointment would be associated with a low potential for phototoxicity but had no potential for skin irritation or photoallergy. In the QBX1‐2 study, it was revealed that the systemic exposure to JTE‐052 in both healthy volunteers with normal skin and AD patients with inflamed skin was low in application of not only 1% but also 3% JTE‐052 ointment. JTE‐052 ointments of 1% and 3% were generally safe and well tolerated in both populations. In a repeated twice‐daily application for 7 days, the efficacy of JTE‐052 ointment to AD patients was observed with both 1% and 3% ointments in the exploratory investigations evaluated by Eczema Area and Severity Index, Investigator's Global Assessment and Numeric Rating Scale assessments. The mean scores for each assessment declined from the baseline throughout the study. These results suggest that the treatment of JTE‐052 ointment is generally safe and effective in AD patients, although further large confirmatory studies are needed.

The skin protective effects of compound K, a metabolite of ginsenoside Rb1 from Panax ginseng

BACKGROUND

Compound K (CK) is a ginsenoside, a metabolite of Panax ginseng. There is interest both in increasing skin health and antiaging using natural skin care products. In this study, we explored the possibility of using CK as a cosmetic ingredient.

METHODS

To assess the antiaging effect of CK, RT-PCR was performed, and expression levels of matrix metalloproteinase-1, cyclooxygenase-2, and type I collagen were measured under UVB irradiation conditions. The skin hydrating effect of CK was tested by RT-PCR, and its regulation was explored through immunoblotting. Melanin content, melanin secretion, and tyrosinase activity assays were performed.

RESULTS

CK treatment reduced the production of matrix metalloproteinase-1 and cyclooxygenase-2 in UVB irradiated NIH3T3 cells and recovered type I collagen expression level. Expression of skin hydrating factors-filaggrin, transglutaminase, and hyaluronic acid synthases-1 and -2-were augmented by CK and were modulated through the inhibitor of κBα, c-Jun N-terminal kinase, or extracellular signal-regulated kinases pathway. In the melanogenic response, CK did not regulate tyrosinase activity and melanin secretion, but increased melanin content in B16F10 cells was observed.

CONCLUSION

Our data showed that CK has antiaging and hydrating effects. We suggest that CK could be used in cosmetic products to protect the skin from UVB rays and increase skin moisture level.

Tabetri™ (Tabebuia avellanedae Ethanol Extract) Ameliorates Atopic Dermatitis Symptoms in Mice

Tabebuia avellanedae has been traditionally used as an herbal remedy to alleviate various diseases. However, the plant's pharmacological activity in allergic and inflammatory diseases and its underlying mechanism are not fully understood. Therefore, we investigated the pharmacological activity of Tabetri (T. avellanedae ethanol extract (Ta-EE)) in the pathogenesis of AD. Its underlying mechanism was explored using an AD mouse model and splenocytes isolated from this model. Ta-EE ameliorated the AD symptoms without any toxicity and protected the skin of 2,4-dinitrochlorobenzene- (DNCB-) induced AD mice from damage and epidermal thickness. Ta-EE reduced the secreted levels of allergic and proinflammatory cytokines, including histamine, immunoglobulin E (IgE), interleukin- (IL-) 4, and interferon-gamma (IFN-γ) in the DNCB-induced AD mice. Ta-EE suppressed the mRNA expression of T helper 2-specific cytokines, IL-4 and IL-5, and the proinflammatory cytokine IFN-γ in the atopic dermatitis skin lesions of AD mice. Moreover, Ta-EE suppressed the mRNA expression of IL-4, IL-5, IFN-γ, and another proinflammatory cytokine, IL-12, in the Con A-stimulated splenocytes. It also suppressed IL-12 and IFN-γ in the LPS-stimulated splenocytes. Taken together, these results suggest that Ta-EE protects against the development of AD through the inhibition of mRNA expression of T helper 2-specific cytokines and other proinflammatory cytokines.

The Effects of a Humor Intervention on the Physiological, Physical, and Psychological Responses of School-aged Children With Atopic Dermatitis in South Korea: A Pilot Study

PURPOSE

We examined the effects of a humor intervention on the physiological, physical, and psychological responses of school-aged children with atopic dermatitis.

DESIGN AND METHODS

This quasi-experimental study used a nonequivalent control group and a pre- and post-test design. Forty-five schoolchildren participated.

RESULTS

Children in the experimental group (n=26) received a humor intervention and reported significant differences in physiological response, which was evidenced by heightened salivary immunoglobulin A levels as compared to the control group (n=19). Additionally, the psychological response of the experimental group was significantly different from that of the control group as evidenced by decreased stress levels.

CONCLUSION

Humor intervention may be an effective nursing intervention for children with atopic dermatitis.

New science and treatment paradigms for atopic dermatitis

PURPOSE OF THE REVIEW

The prevalence of atopic dermatitis is increasing in industrialized countries for unclear reasons. One theory centers on reduced exposure to microbes during infancy and childhood. Alterations in the epidermal permeability barrier, place certain patients at risk for the immunological dysfunction seen in atopic dermatitis. This review examines current research pertaining to the epidermal permeability barrier, the cutaneous microbiome, and the immunology of atopic dermatitis. New collaborative research has led to evidence-based management guidelines.

RECENT FINDINGS

Increased skin barrier permeability and dysfunction of innate and adaptive immunity cause atopic dermatitis. Genetic and environmental factors leading to decreased filaggrin underlie many cases of atopic dermatitis. Defective epidermal barrier function allows for an increased density of Staphylococcus aureus and a subsequent shift in adaptive immunity to a type 2 immune response. Multiple evaluation and management guidelines have been published based on current available evidence. These guidelines highlight state of the art management of seven main areas: inflammation, infection, irritation, itch, ichthyosis (dry skin), immunological influences, and impeding (comorbid) conditions.

SUMMARY

Pediatricians are central to the successful diagnosis and management of atopic dermatitis. Increased basic and clinical research and well published clinical guidelines will lead to improved outcomes for the patients and families affected by this chronic relapsing disorder.

Efficacy and safety of topical JTE-052, a Janus kinase inhibitor, in Japanese adult patients with moderate-to-severe atopic dermatitis: a phase II, multicentre, randomized, vehicle-controlled clinical study

BACKGROUND

JTE-052 is a novel Janus kinase inhibitor presently under clinical development for the topical treatment of atopic dermatitis (AD).

OBJECTIVES

To evaluate the efficacy and safety of JTE-052 ointment in Japanese adult patients with AD.

METHODS

Patients with moderate-to-severe AD were randomized (2: 2: 2: 2: 1: 1) to receive JTE-052 ointment at 0·25%, 0·5%, 1% or 3%, the vehicle ointment or tacrolimus 0·1% ointment (reference) twice daily for 4 weeks. The primary efficacy end point was the percentage change in modified Eczema Area Severity Index (mEASI) score from baseline at the end of treatment (EOT). Secondary efficacy end points included change from baseline in the pruritus numerical rating scale (NRS) score.

RESULTS

In total, 327 patients were enrolled. At EOT, the least-squares mean percentage changes from baseline in mEASI score for JTE-052 at 0·25%, 0·5%, 1% and 3% and the vehicle ointment were -41·7%, -57·1%, -54·9%, -72·9% and -12·2%, respectively. All JTE-052 groups showed significant reductions of mEASI score vs. the vehicle group (P < 0·001 for all). In the tacrolimus group, the mean percentage change in mEASI score was -62·0%. The JTE-052 groups also showed significant improvement in other parameters; notably, the pruritus NRS score was reduced as early as day 1 night-time. JTE-052 ointment at doses up to 3% was safe and well tolerated.

CONCLUSIONS

Topical JTE-052 markedly and rapidly improved clinical signs and symptoms in Japanese adult patients with moderate-to-severe AD, with a favourable safety profile. The study results indicate that topical JTE-052 is a promising therapeutic option for AD. The trial registration number is JapicCTI-152887.

Barrier dysfunction in the skin allergy

The skin is continuously exposed to external pathogens, and its barrier function is critical for skin homeostasis. Previous studies have shown that the barrier dysfunction is one of the most predisposing factors for the development of skin allergic diseases such as atopic dermatitis. In this article, we summarize how the physical barrier of the skin is organized and review its link to the pathomechanism of skin allergic diseases. We describe the formation of the SC barrier in terms of the following five categories: 1) filaggrin metabolism; 2) cornified envelope; 3) intercellular lipids; 4) corneodesmosome; and 5) corneocyte desquamation. New approaches to restoring the skin barrier function are also discussed.

Prostaglandin E2 stimulates adaptive IL-22 production and promotes allergic contact dermatitis

BACKGROUND

Atopic dermatitis (AD) and allergic contact dermatitis (ACD) are both forms of eczema and are common inflammatory skin diseases with a central role of T cell-derived IL-22 in their pathogenesis. Although prostaglandin (PG) E2 is known to promote inflammation, little is known about its role in processes related to AD and ACD development, including IL-22 upregulation.

OBJECTIVES

We sought to investigate whether PGE2 has a role in IL-22 induction and development of ACD, which has increased prevalence in patients with AD.

METHODS

T-cell cultures and in vivo sensitization of mice with haptens were used to assess the role of PGE2 in IL-22 production. The involvement of PGE2 receptors and their downstream signals was also examined. The effects of PGE2 were evaluated by using the oxazolone-induced ACD mouse model. The relationship of PGE2 and IL-22 signaling pathways in skin inflammation were also investigated by using genomic profiling in human lesional AD skin.

RESULTS

PGE2 induces IL-22 from T cells through its receptors, E prostanoid receptor (EP) 2 and EP4, and involves cyclic AMP signaling. Selective deletion of EP4 in T cells prevents hapten-induced IL-22 production in vivo, and limits atopic-like skin inflammation in the oxazolone-induced ACD model. Moreover, both PGE2 and IL-22 pathway genes were coordinately upregulated in human AD lesional skin but were at less than significant detection levels after corticosteroid or UVB treatments.

CONCLUSIONS

Our results define a crucial role for PGE2 in promoting ACD by facilitating IL-22 production from T cells.

The Role of Moisturizers in Addressing Various Kinds of Dermatitis: A Review

Moisturizer is a major component of basic daily skin care, particularly in presence of epidermal barrier alteration and reduced epidermal water content. It is an important part of a dermatologist's strategy to maintain skin health as well as treating various dermatoses which co-exist with skin dryness and are linked to impaired skin barrier function, such as in atopic disorders as well as other types of dermatitis. Mastering the knowledge regarding mechanism of action, application, dosage, adverse effects as well as specific clinical usage of moisturizers is a must for a dermatologist in order to support their use, particularly for evidence-based, therapeutic purposes. This review discusses the use of moisturizer both for skin health maintenance as well as a definitive or adjuvant therapy for many kinds of dermatitis.

Biological Therapeutic Treatment of Atopic Dermatitis

Atopic dermatitis is a chronic recurrent inflammatory disease caused, inter alia, by violations of the barrier function of the skin and pathological immune response in the form of an imbalance of Th1 and Th2 lymphocytes with increased production of IL-4, IL-5, IL-13, IL-31. Treatment of severe forms of atopic dermatitis is not an easy task due to the variability of the individual response to treatment, the short duration of the therapeutic effect and the frequent development of undesirable phenomena associated with the use of existing methods of systemic immunosuppressive therapy. The study of the pathogenesis of atopic dermatitis made it possible to identify the spectrum of molecular targets, providing the basis for researching alternative variants to the previously used systemic therapy methods – genetic engineering biological preparations. Contemporary data on the pathogenesis of atopic dermatitis as well as potential molecular targets for innovative biological preparations, the efficacy of which has been evaluated through clinical trials, are presented in the review. 

Analysis of chromatin accessibility in human epidermis identifies putative barrier dysfunction-sensing enhancers

To identify putative gene regulatory regions that respond to epidermal injury, we mapped chromatin dynamics in a stratified human epidermis during barrier maturation and disruption. Engineered skin substitutes (ESS) cultured at the air-liquid interface were used as a model of developing human epidermis with incomplete barrier formation. The epidermal barrier stabilized following engraftment onto immunocompromised mice, and was compromised again upon injury. Modified formaldehyde-assisted isolation of regulatory elements (FAIRE) was used to identify accessible genomic regions characteristic of monolayer keratinocytes, ESS in vitro, grafted ESS, and tape-stripped ESS graft. We mapped differentiation- and maturation-associated changes in transcription factor binding sites enriched at each stage and observed overrepresentation of AP-1 gene family motifs in barrier-deficient samples. Transcription of TSLP, an important effector of immunological memory in response to allergen exposure, was dramatically elevated in our barrier-deficient samples. We identified dynamic DNA elements that correlated with TSLP induction and may contain enhancers that regulate TSLP. Two dynamic regions were located near the TSLP promoter and overlapped with allergy-associated SNPs rs17551370 and rs2289877, strongly implicating these loci in the regulation of TSLP expression in allergic disease. Additional dynamic chromatin regions ~250kb upstream of the TSLP promoter were found to be in high linkage disequilibrium with allergic disease SNPs. Taken together, these results define dynamic chromatin accessibility changes during epidermal development and dysfunction.

Revisiting murine models for atopic dermatitis and psoriasis with multipolar cytokine axes

Atopic dermatitis (AD) and psoriasis are one of the common skin diseases. Animal models are a powerful tool to analyze these diseases, which are complicated by multiple cytokine pathways. However, many discrepancies between the human diseases and murine models have been noticed. Therefore, investigators should be aware of the differences between the murine AD models and human AD when translating murine data to human skin diseases. This review highlights the differences between the inflammatory profiles between murine models and human diseases focusing on AD and psoriasis.

Modulation of CD4+ T Helper Cell Memory Responses in the Human Skin

Immunological memory is defined as the capacity to mount faster and more effective immune responses against antigenic challenges that have been previously encountered by the host. CD4+ T helper (Th) cells play central roles in the establishment of immunological memory as they assist the functions of other leukocytes. Th cells express polarized cytokine profiles and distinct migratory and seeding capacities, but also retain a certain functional plasticity that allows them to modulate their proliferation, activity, and homing behaviour upon need. Thus, in healthy individuals, T cell immunomodulation fulfils the task of eliciting protective immune responses where they are needed. At times, however, Th plasticity can lead to collateral tissue damage and progression to autoimmune diseases or, conversely, incapacity to reject malignant tissues and clear chronic infections. Furthermore, common immune players and molecular pathways of diseases can lead to different outcomes in different individuals. A mechanistic understanding of those pathways is therefore crucial for developing precise and curative medical interventions. Here, I focus on the skin microenvironment and comprehensively describe some of the cellular and molecular determinants of CD4+ T cell memory responses in homeostatic and pathological conditions. In discussing the cellular network orchestrating cutaneous immunity, I comprehensively describe the bidirectional interaction of skin antigen-presenting cells and mononuclear phagocytes with Th17 lymphocytes, and examine how the outcome of this interaction is influenced by endogenous skin molecules, including sodium salts and neuropeptides.

Current insights into the role of human β-defensins in atopic dermatitis

Anti-microbial peptides or host defence peptides are small molecules that display both anti-microbial activities and complex immunomodulatory functions to protect against various diseases. Among these peptides, the human β-defensins (hBDs) are localized primarily in epithelial surfaces, including those of the skin, where they contribute to protective barriers. In atopic dermatitis skin lesions, altered skin barrier and immune dysregulation are believed to be responsible for reduced hBD synthesis. Impaired hBD expression in the skin is reportedly the leading cause of increased susceptibility to bacterial and viral infection in patients with atopic dermatitis. Although hBDs have considerable beneficial effects as anti-microbial agents and immunomodulators and may ameliorate atopic dermatitis clinically, recent evidence has also suggested the negative effects of hBDs in atopic dermatitis development. In the current review, we provide an overview of the regulation of hBDs and their role in the pathogenesis of atopic dermatitis. The efforts to utilize these molecules in clinical applications are also described.

Atopic Dermatitis Studies through In Vitro Models

Atopic dermatitis (AD) is a complex inflammatory skin condition that is not fully understood. Epidermal barrier defects and Th2 immune response dysregulations are thought to play crucial roles in the pathogenesis of the disease. A vicious circle takes place between these alterations, and it can further be complicated by additional genetic and environmental factors. Studies investigating in more depth the etiology of the disease are thus needed in order to develop functional treatments. In recent years, there have been significant advances regarding in vitro models reproducing important features of AD. However, since a lot of models have been developed, finding the appropriate experimental setting can be difficult. Therefore, herein, we review the different types of in vitro models mimicking features of AD. The simplest models are two-dimensional culture systems composed of immune cells or keratinocytes, whereas three-dimensional skin or epidermal equivalents reconstitute more complex stratified tissues exhibiting barrier properties. In those models, hallmarks of AD are obtained, either by challenging tissues with interleukin cocktails overexpressed in AD epidermis or by silencing expression of pivotal genes encoding epidermal barrier proteins. Tissue equivalents cocultured with lymphocytes or containing AD patient cells are also described. Furthermore, each model is placed in its study context with a brief summary of the main results obtained. In conclusion, the described in vitro models are useful tools to better understand AD pathogenesis, but also to screen new compounds in the field of AD, which probably will open the way to new preventive or therapeutic strategies.

Advances in atopic dermatitis in 2015

This review aims to highlight recently published articles on atopic dermatitis (AD). Updated are the insights into epidemiology, pathology, diagnostics, and therapy. Epidemiologic studies have revealed a positive correlation between AD and systemic conditions, such as rheumatoid arthritis, inflammatory bowel disease, and neonatal adiposity. Pathologic findings highlight the involvement of novel barrier factors (desmoplakin and claudin), novel immune cell subsets (pathogenic effector T_H2 cells and group 2 innate lymphoid cells), and differential skewing of helper T cells (eg, T_H17 dominance in Asians with AD). As diagnostics, noninvasive examinations of the transepidermal water loss of neonates, the density of epidermal Staphylococcus species, and the gut flora might prognosticate the onset of AD. As for therapy, various methods are proposed, including conventional (petrolatum and UV) and molecule-oriented regimens targeting Janus kinase, signal transducer and activator of transcription 3, extracellular signal-regulated kinase, sirtuin 1, or aryl hydrocarbon receptor.

Advances in atopic dermatitis and urticarial in 2016

This review highlights recent key advances in the pathology and therapies of inflammatory skin diseases, focusing on atopic dermatitis (AD) and chronic spontaneous urticaria (CSU). Regarding AD, transcriptomic analysis with human samples revealed different immune profiles between childhood and adult AD. Phase III clinical trials of dupilumab, an anti-IL-4 receptor α antibody, in the treatment of AD have successfully finished, and dupilumab will appear in clinical practice as the first biologic for AD in 2017. In addition, a novel biologic that targets IL-31 shows promising results in a phase II trial. As for the skin microbiome study, novel insights into the mechanisms of microbial dysbiosis, such as colonization of Staphylococcus aureus, a common feature of AD, were proposed. Regarding CSU, autoreactive CD4⁺ T cells that react to FcεRI were discovered, which might contribute to the development of CSU. These findings provide new insights into the pathogenesis of AD and CSU and will lead to more specific and personalized treatments.

The etiopathogenesis of atopic dermatitis: barrier disruption, immunological derangement, and pruritus

Atopic dermatitis (AD) is a common chronic skin inflammatory disorder characterized by recurrent eczema accompanied by an intractable itch that leads to an impaired quality of life. Extensive recent studies have shed light on the multifaceted pathogenesis of the disease. The complex interplay among skin barrier deficiency, immunological derangement, and pruritus contributes to the development, progression, and chronicity of the disease. Abnormalities in filaggrin, other stratum corneum constituents, and tight junctions induce and/or promote skin inflammation. This inflammation, in turn, can further deteriorate the barrier function by downregulating a myriad of essential barrier-maintaining molecules. Pruritus in AD, which may be due to hyperinnervation of the epidermis, increases pruritogens, and central sensitization compromises the skin integrity and promotes inflammation. There are unmet needs in the treatment of AD. Based on the detailed evidence available to date, certain disease mechanisms can be chosen as treatment targets. Numerous clinical trials of biological agents are currently being conducted and are expected to provide treatments for patients suffering from AD in the future. This review summarizes the etiopathogenesis of the disease and provides a rationale for choosing the novel targeted therapy that will be available in the future.

Crowdsourced Identification of Possible Allergy-Associated Factors: Automated Hypothesis Generation and Validation Using Crowdsourcing Services

BACKGROUND

Hypothesis generation is an essential task for clinical research, and it can require years of research experience to formulate a meaningful hypothesis. Recent studies have endeavored to apply crowdsourcing to generate novel hypotheses for research. In this study, we apply crowdsourcing to explore previously unknown allergy-associated factors.

OBJECTIVE

In this study, we aimed to collect and test hypotheses of unknown allergy-associated factors using a crowdsourcing service.

METHODS

Using a series of questionnaires, we asked crowdsourcing participants to provide hypotheses on associated factors for seven different allergies, and validated the candidate hypotheses with odds ratios calculated for each associated factor. We repeated this abductive validation process to identify a set of reliable hypotheses.

RESULTS

We obtained two primary findings: (1) crowdsourcing showed that 8 of the 13 known hypothesized allergy risks were statically significant; and (2) among the total of 157 hypotheses generated by the crowdsourcing service, 75 hypotheses were statistically significant allergy-associated factors, comprising the 8 known risks and 53 previously unknown allergy-associated factors. These findings suggest that there are still many topics to be examined in future allergy studies.

CONCLUSIONS

Crowdsourcing generated new hypotheses on allergy-associated factors. In the near future, clinical trials should be conducted to validate the hypotheses generated in this study.

Clinical Practice Guidelines for the Management of Atopic Dermatitis 2016

Atopic dermatitis (AD) is a disease characterized by relapsing eczema with pruritus as a primary lesion. Most patients have an atopic predisposition. The definitive diagnosis of AD requires the presence of all three features: (i) pruritus; (ii) typical morphology and distribution of the eczema; and (iii) chronic and chronically relapsing course. The current strategies to treat AD in Japan from the perspective of evidence-based medicine consist of three primary measures: (i) the use of topical corticosteroids and tacrolimus ointment as the main treatment for the inflammation; (ii) topical application of emollients to treat the cutaneous barrier dysfunction; and (iii) avoidance of apparent exacerbating factors, psychological counseling and advice about daily life. The guidelines present recommendations to review clinical research articles, evaluate the balance between the advantages and disadvantages of medical activities, and optimize medical activity-related patient outcomes with respect to several important points requiring decision-making in clinical practice.

The Role of Interleukins 4 and/or 13 in the Pathophysiology and Treatment of Atopic Dermatitis

Moderate to severe atopic dermatitis (AD) can be debilitating and often requires use of systemic immunosuppressant therapy to achieve adequate disease control. There are currently no US Food and Drug Administration-approved systemic agents for the long-term treatment of AD. Recent insight has identified the T helper 2 cytokines, interleukins 4 and 13, as playing a major role in the pathogenesis of AD. There are multiple novel biologic agents in development that target interleukins 4 and/or 13 for the treatment of moderate to severe AD. The age of targeted biologics for AD has arrived.

Current and emerging concepts in atopic dermatitis pathogenesis

Atopic dermatitis is a common skin disorder with a complex, evolving pathogenesis. Research on the pathogenesis has shifted from focusing primarily on generalized immune system abnormalities in T helper 1/T helper 2 (T_h1/T_h2) activity to more targeted immune and skin barrier abnormalities contributing to the overall phenotype. Specific signaling pathways recently implicated in atopic dermatitis include production of interleukin (IL) 4 and IL-13, which promote immunoglobulin E production, T_h17 and T_h22 cells, and production of cytokines. Barrier defect abnormalities, such as a shared filaggrin mutation noted in ichthyosis vulgaris and atopic dermatitis, as well as reduced structural proteins and lipids (eg, ceramides), have been discovered as well. These alterations contribute to increased transepidermal water loss in addition to increased allergen exposure, resulting in debate over the "inside out" versus "outside in" theories-that is, the concept that immunity triggers barrier breakdown versus barrier abnormalities triggering immunologic alteration toward atopy. In fact, it is likely that all of these contribute to pathogenesis, with some individuals initially experiencing immunologic abnormalities more strongly than barrier defects and vice versa. Genetic analyses have continued to advance, leading to the discovery of potential candidate genes relating both to the impaired skin barrier and the altered immune system pathways. This review outlines the evolution of the field of current pathogenesis of atopic dermatitis, highlighting the most pertinent recent findings.

Anti-Interleukin-31 Receptor A Antibody for Atopic Dermatitis

BACKGROUND

Interleukin-31 may play a role in the pathobiologic mechanism of atopic dermatitis and pruritus. We wanted to assess the efficacy and safety of nemolizumab (CIM331), a humanized antibody against interleukin-31 receptor A, in the treatment of atopic dermatitis.

METHODS

In this phase 2, randomized, double-blind, placebo-controlled, 12-week trial, we assigned adults with moderate-to-severe atopic dermatitis that was inadequately controlled by topical treatments to receive subcutaneous nemolizumab (at a dose of 0.1 mg, 0.5 mg, or 2.0 mg per kilogram of body weight) or placebo every 4 weeks or an exploratory dose of 2.0 mg of nemolizumab per kilogram every 8 weeks. The primary end point was the percentage improvement from baseline in the score on the pruritus visual-analogue scale (on which a negative change indicates improvement) at week 12. Secondary end points included changes in the score on the Eczema Area and Severity Index (EASI, on which a negative change indicates improvement), and body-surface area of atopic dermatitis.

RESULTS

Of 264 patients who underwent randomization, 216 (82%) completed the study. At week 12, among the patients who received nemolizumab every 4 weeks, changes on the pruritus visual-analogue scale were -43.7% in the 0.1-mg group, -59.8% in the 0.5-mg group, and -63.1% in the 2.0-mg group, versus -20.9% in the placebo group (P<0.01 for all comparisons). Changes on the EASI were -23.0%, -42.3%, and -40.9%, respectively, in the nemolizumab groups, versus -26.6% in the placebo group. Respective changes in body-surface area affected by atopic dermatitis were -7.5%, -20.0%, and -19.4% with nemolizumab, versus -15.7% with placebo. Among the patients receiving nemolizumab every 4 weeks, treatment discontinuations occurred in 9 of 53 patients (17%) in the 0.1-mg group, in 9 of 54 (17%) in the 0.5-mg group, and in 7 of 52 (13%) in the 2.0-mg group, versus in 9 of 53 (17%) in the placebo group.

CONCLUSIONS

In this phase 2 trial, nemolizumab at all monthly doses significantly improved pruritus in patients with moderate-to-severe atopic dermatitis, which showed the efficacy of targeting interleukin-31 receptor A. The limited size and length of the trial preclude conclusions regarding adverse events. (Funded by Chugai Pharmaceutical; XCIMA ClinicalTrials.gov number, NCT01986933 .).

Glycomacropeptide Attenuates Inflammation, Pruritus, and Th2 Response Associated with Atopic Dermatitis Induced by 2,4-Dinitrochlorobenzene in Rat

Atopic dermatitis (AD) is one of the most common skin diseases, whose incidence is increasing in industrialized countries. The epicutaneous application of a hapten, such as 2,4-dinitrochlorobenzene (DNCB), evokes an experimental murine AD-like reaction. Glycomacropeptide (GMP) is a dairy bioactive peptide derived from hydrolysis of κ-casein by chymosin action. It has anti-inflammatory, prebiotic, and immunomodulatory effects. The present study was aimed to investigate the effect of GMP administration on DNCB-induced AD in rats. The severity of inflammatory process, pruritus, production of cytokines, and total immunoglobulin E (IgE) content were measured, and the histopathological features were analyzed. GMP reduced the intensity of inflammatory process and edema of DNCB-induced dermatitis, with a significant decrease in eosinophils recruitment and mast cells hyperplasia. In addition GMP suppressed the serum levels of total IgE and IL-4, IL-5, and IL-13 expression in AD-lesions. Besides, the levels of IL-10 were significantly increased. Remarkably, GMP administration before AD-induction abolished pruritus in dermatitis-like reactions in the rats. Taken together, these results indicate that GMP has an inhibitory effect on AD by downregulating Th2 dominant immune response, suggesting GMP as a potential effective alternative therapy for the prevention and management of AD.

Yogurt consumption in infancy is inversely associated with atopic dermatitis and food sensitization at 5 years of age: A hospital-based birth cohort study

BACKGROUND

Several studies have suggested that habitual yogurt consumption is associated with favorable outcomes for health issues in children. However, the effects of yogurt consumption on allergic diseases and sensitization in children remain poorly understood.

OBJECTIVE

This prospective birth cohort study aimed to investigate for associations between habitual yogurt consumption in infancy and development of allergic diseases/sensitization at 5 years of age.

METHODS

Data were obtained from the Tokyo Children's Health, Illness and Development (T-CHILD) study. A total of 1550 children were born to the recruited women. Consumption of yogurt by children during infancy was determined by using questionnaires completed at 12 months of age. Outcome data for children were collected from the questionnaires and medical check-ups completed at 5 years of age. Possible associations between habitual yogurt consumption in infancy and allergic diseases/sensitization were analyzed by multiple logistic regression analyses.

RESULTS

We analyzed the data for 1166 children whose parents responded at 5 years of age. Habitual yogurt consumption in infancy and atopic dermatitis at 5 years of age were significantly associated (UKWP criteria: aOR, 0.70; 95% CI, 0.51-0.97; P=0.03). Children with habitual yogurt consumption in infancy were less likely to be sensitized to food allergens (aOR, 0.53; 95% CI, 0.31-0.93; P=0.03), but no associations were seen in regard to any other allergens.

CONCLUSIONS

Our study demonstrated that habitual consumption of yogurt in infancy has the potential to prevent development of atopic dermatitis and food sensitization, but not other allergic diseases, at 5 years of age.

Epicutaneous Sensitization in Patients with Atopic Dermatitis

Atopic dermatitis (AD) is the most common chronic skin disorder among infants and young children. It is characterized by chronic relapsing eczema with itch and is caused by skin barrier dysfunction and immunological dysregulation. Scratching of the lesion site can damage the skin and increase epithelial permeability, thereby allowing large molecular weight antigens to be absorbed transcutaneously. However, a recent study demonstrated that Langerhans cells are localized close below the skin surface and extend dendrites vertically to penetrate the tight junctions (TJs) in erythematous lesions, even though the TJs were functionally intact. Therefore, epidermal barrier disruption per se is not critical for antigen uptake by Langerhans cells. In contrast, 2 critical damage-associated patterns-IL-33 and IL-1alpha-are reportedly released from damaged epithelial cells. Dendritic cells activated by IL-33 and thymic stromal lymphopoietin (TSLP) (induced by IL-1 alpha) express MHC class II and costimulatory molecules and facilitate naive T cell differentiation into IL-5- and IL-13-secreting Th2 cells. IL-33 and TSLP also activate type 2 innate lymphoid cells, induce large amounts of IL-5 and IL-13, and participate in the pathogenesis of AD. Primary prevention and proactive treatment of AD are critically important for preventing epicutaneous sensitization in AD patients. However, future studies are required to elucidate the most beneficial primary prevention strategies, including the indicated patient cohort and the timing and method of their application.

The aryl hydrocarbon receptor AhR links atopic dermatitis and air pollution via induction of the neurotrophic factor artemin

Atopic dermatitis is increasing worldwide in correlation with air pollution. Various organic components of pollutants activate the transcription factor AhR (aryl hydrocarbon receptor). Through the use of AhR-CA mice, whose keratinocytes express constitutively active AhR and that develop atopic-dermatitis-like phenotypes, we identified Artn as a keratinocyte-specific AhR target gene whose product (the neurotrophic factor artemin) was responsible for epidermal hyper-innervation that led to hypersensitivity to pruritus. The activation of AhR via air pollutants induced expression of artemin, alloknesis, epidermal hyper-innervation and inflammation. AhR activation and ARTN expression were positively correlated in the epidermis of patients with atopic dermatitis. Thus, AhR in keratinocytes senses environmental stimuli and elicits an atopic-dermatitis pathology. We propose a mechanism of air-pollution-induced atopic dermatitis via activation of AhR.

Modelling atopic dermatitis during the morphogenetic process involved in reconstruction of a human epidermis

Most crucial role of epidermis is to maintain efficient barrier between the organism and its environment. This barrier is however perturbed in inflammatory skin conditions like atopic dermatitis (AD), one common chronic disease. This review depicts characteristics of a model intending to reproduce epidermal features of AD in vitro. Firstly, methyl-β-cyclodextrin (MβCD) during reconstruction of epidermis was used to deplete cholesterol from plasma membrane because this condition reproduces characteristics of AD at transcriptomic level in monolayer cultures. Major changes are confirmed after same treatment inside reconstructed human epidermis (RHE). However, since early treatment do not reveal impairment to reconstruct a functional epidermal barrier and given the importance of the Th2 dysregulated immune response in AD, cholesterol-depleted RHE at day 11 of reconstruction were then incubated with three Th2-related cytokines (IL-4, IL-13 and IL-25) previously reported as playing important roles in the development of AD, as well as altering overall function of epidermal barrier. When combining both treatments, essential epidermal features of AD are observed. Indeed, RHE then exhibit spongiosis, disappearing granular layer, alteration of barrier function, as well as dysregulated expression levels for genes involved in AD pathogenesis. Moreover, while trying to identify individual roles for each component used to create AD-like alterations, incubation with IL-4 following cholesterol depletion from plasma membrane was found inducing most of the reported alterations. This model suggests potential for better investigations of epidermal AD features and may be considered for eventual in vitro screening of cosmetics or therapeutic compounds.

Major differences between human atopic dermatitis and murine models, as determined by using global transcriptomic profiling

BACKGROUND

Atopic dermatitis (AD) is caused by a complex interplay between immune and barrier abnormalities. Murine models of AD are essential for preclinical assessments of new treatments. Although many models have been used to simulate AD, their transcriptomic profiles are not fully understood, and a comparison of these models with the human AD transcriptomic fingerprint is lacking.

OBJECTIVE

We sought to evaluate the transcriptomic profiles of 6 common murine models and determine how they relate to human AD skin.

METHODS

Transcriptomic profiling was performed by using microarrays and quantitative RT-PCR on biopsy specimens from NC/Nga, flaky tail, Flg-mutated, ovalbumin-challenged, oxazolone-challenged, and IL-23-injected mice. Gene expression data of patients with AD, psoriasis, and contact dermatitis were obtained from previous patient cohorts. Criteria of a fold change of 2 or greater and a false discovery rate of 0.05 or less were used for gene arrays.

RESULTS

IL-23-injected, NC/Nga, and oxazolone-challenged mice show the largest homology with our human meta-analysis-derived AD transcriptome (37%, 18%, 17%, respectively). Similar to human AD, robust T_H1, T_H2, and also T_H17 activation are seen in IL-23-injected and NC/Nga mice, with similar but weaker inflammation in ovalbumin-challenged mice. Oxazolone-challenged mice show a T_H1-centered reaction, and flaky tail mice demonstrate a strong T_H17 polarization. Flg-mutated mice display filaggrin downregulation without significant inflammation.

CONCLUSION

No single murine model fully captures all aspects of the AD profile; instead, each model reflects different immune or barrier disease aspects. Overall, among the 6 murine models, IL-23-injected mice best simulate human AD; still, the translational focus of the investigation should determine which model is most applicable.

JAK inhibitor JTE-052 regulates contact hypersensitivity by downmodulating T cell activation and differentiation

BACKGROUND

Using JAK inhibitors to inhibit cytokine signaling is presumed to be a possible means of treating skin inflammatory disorders such as contact dermatitis.

OBJECTIVE

To clarify the action site of JAK inhibitors in skin inflammatory disorders.

METHODS

We analyzed the mechanism of action of the JAK inhibitor JTE-052 using murine skin inflammation models, including contact hypersensitivity (CHS) and irritant contact dermatitis. Cells isolated from ear tissue or lymph node (LN) were analyzed by flow cytometry. The amounts of cytokines in the culture medium were measured by ELISA or bead array system. Proliferation of LN cells was evaluated by measurement of tritiated thymidine incorporation.

RESULTS

Oral administration of JTE-052 during both sensitization and elicitation phase attenuated CHS, but did not affect croton oil-induced irritant contact dermatitis. JTE-052 potently inhibited T cell proliferation and activation by antigen presentation in vitro, and attenuated skin inflammation in a sensitized-lymphocyte transfer model without suppressing T cell migration. JTE-052 did not affect hapten-induced cutaneous dendritic cell migration into draining lymph nodes or their costimulatory molecule expressions.

CONCLUSION

The JAK inhibitor JTE-052 exerts an inhibitory effect on antigen-specific T cell activation and subsequent inflammation in acquired skin immunity, such as CHS.

Cyclosporin A Treatment in Intrinsic Canine Atopic Dermatitis (Atopic-like Dermatitis): Open Trial Study

In this study, dogs were separated into two groups and treated with immunosuppressant (Cyclosporin A: CsA). The first group was the canine atopic dermatitis (CAD) group, which is similar to extrinsic atopic dermatitis (AD) in humans (treated with a CsA dose of 2.5-5.5 mg/kg, n=8), and the second group was the canine atopic-like dermatitis (ALD) group, which is similar to intrinsic AD in humans (treated with a CsA dose of 2.5-6.5 mg/kg, n=14). The canine atopic dermatitis extent and severity index (CADESI)-4 was evaluated before treatment (PRE) and after treatment (POST) to assess the effectiveness of CsA for the two groups. In the CAD group, CADESI-4 showed no change (PRE:79±29, POST:77±28) and out of the eight dogs, no dogs showed complete remission, three dogs showed partial remission, and five dogs showed no effect. Whereas in the ALD group, CADESI-4 showed a significant reduction (PRE: 61±42, POST: 32±25, p<0.01) and out of the 14 dogs, 11 dogs showed complete remission, two dogs showed partial remission, and one dog showed no effect. The results indicate that the immunosuppressant showed effectiveness for the dogs diagnosed with ALD. One dog had to be treated for a year and eight months, which was the longest period in the study, this dog presented with hyperplasia of the lymphoidgland and mammary tumor.