Current novel approaches in systemic therapy of atopic dermatitis: specific inhibition of cutaneous Th2 polarized inflammation and itch

Higher-order sensorimotor circuit of the whole-brain functional network involved in pruritus regulation in atopic dermatitis

BACKGROUND

Little is known about the neural mechanisms underlying pruritus regulation in Atopic dermatitis (AD).

OBJECTIVE

To investigate the functional changes of the resting-state whole brain network of AD participants and the mechanisms by which they were involved in pruritus regulation.

METHOD

Based on the functional magnetic resonance imaging data from 19 AD participants and 37 healthy controls (HC), a graph-theoretical measure of degree centrality (DC) conjoined with a voxel-level seed-based functional connectivity (FC) method was used to identify abnormal higher-order nodes and the functionally relevant circuit in AD participants compared to healthy controls (HC).

RESULTS

Of 64 participants screened, 19 AD participants (12M/7F, median [IQR] age, 27 [14] years) and 36 HCs (13M/23F, median [IQR] age, 20 [1] years) were enrolled. DC values of the left superior frontal gyrus (LSFG) increased in AD participants and exhibited a negative correlation with the SCORAD score (r = -0.561, p = 0.012) compared with HC. In the FC analysis with LSFG as the seed, FC values of several sensory and motor regions increased in AD participants, highly overlapping with the anatomical distribution of the inferior fronto-occipital fascicle (IFOF). AD participants with severe pruritus exhibited lower levels of DC (T = -2.316, p = 0.033) and FC between the LSFG and left insula (T = -2.203, p = 0.042) than those with mild-to- moderate pruritus.

CONCLUSIONS AND RELEVANCE

LSFG was involved in pruritus regulation in AD by forming a high-order sensorimotor circuit through the IFOF, a white matter fascicle that proved to provide multimodal integration in motor control and sensory information processing. These results offer more mechanism-guided treatment targets for severe pruritus in AD.

T-cell receptor sequencing specifies psoriasis as a systemic and atopic dermatitis as a skin-focused, allergen-driven disease

BACKGROUND

Atopic dermatitis (AD) and psoriasis represent two of the most common inflammatory skin diseases in developed countries. A hallmark of both diseases is T-cell infiltration into the skin. However, it is still not clarified to what extent these infiltrating T cells are antigen-specific skin-homing T cells or unspecific heterogeneous bystander cells.

METHODS

To elucidate this, T cells from lesional skin and from blood of 9 AD and 10 psoriasis patients were compared by receptor (TCR) sequencing. Therefore, peripheral blood mononuclear cells (PBMC) were cell-sorted according to expression of the cutaneous leukocyte antigen (CLA) into skin-homing (CLA⁺ ) and non-skin-homing (CLA^- ) subfractions. Aeroallergen-specific T-cell lines were grown from AD patients' PBMC in parallel.

RESULTS

Intra-individual comparison of TCRB CDR3 regions revealed that clonally expanded T cells in skin lesions of both AD and psoriasis patients corresponded to skin-homing circulating T cells. However, in psoriasis patients, these T-cell clones were also detectable to a larger extent among CLA^- circulating T cells. Up to 28% of infiltrating cells in AD skin were identified as allergen-specific by overlapping TCR sequences.

CONCLUSIONS

Our data show that in line with the systemic nature of psoriasis, T-cell clones that infiltrate psoriatic skin lesions do not exclusively possess skin-homing ability and are therefore most probably specific to antigens that are not exclusively expressed or located in the skin. T cells driving AD skin inflammation appear to home nearly exclusively to the skin and are, to a certain extent, specific to aeroallergens.

Prevalence of, and factors associated with, long-term COVID-19 sick leave in working-age patients followed in general practices in Germany

Objectives

To investigate the prevalence of, and the factors associated with, long-term sick leave in working-age patients diagnosed with COVID-19 in general practices in Germany.

Methods

Patients aged 18–65 years diagnosed with COVID-19 in any of 1255 general practices in Germany between March 2020 and February 2021 were included in the study. Long-term sick leave was defined as sick leave of at least 4 weeks. The association between predefined independent variables and long-term sick leave was studied using an adjusted logistic regression model.

Results

This study included 30 950 patients diagnosed with COVID-19 (51.7% women, mean (standard deviation) age 41.5 (±13.0) years). The prevalence of long-term sick leave was 5.8%. Female sex, older age, and several conditions (noninfective enteritis and colitis; reaction to severe stress, and adjustment disorders; atopic dermatitis; mononeuropathies; reflux diseases; diabetes mellitus; and hypertension) were positively and significantly associated with long-term sick leave.

Conclusion

Long-term sick leave was relatively rare in COVID-19 patients followed in general practices in Germany. These results should be confirmed or invalidated in other settings and countries.

Dupilumab for atopic dermatitis: evidence to date

INTRODUCTION

Atopic dermatitis (AD) is a common chronic, pruritic inflammatory dermatosis. The inflammatory response is characterized by a T helper 2 (Th2) immune response phenotype.

EVIDENCE ACQUISITION

To assess current available data on dupilumab, the writers of this article did a comprehensive search in different databases, including Medline, EMBASE, SCOPUS, and clinical trial registries. All relevant articles identified were then manually reviewed. Information regarding dupilumab mechanism of action, pharmacokinetics, clinical efficacy, safety, and future trends was then summarized.

EVIDENCE SYNTHESIS

Topical therapy is the main treatment in mild-to-moderate AD, but many cases of moderate-to-severe require systemic treatments. Dupilumab is the first biologic approved for the treatment of adults with moderate-to-severe AD. It inhibits IL-4 and IL-13 signaling pathways and reduces Th2 response. Clinical trials have demonstrated significantly improved clinical and patient-reported outcomes. The addition of application of topical corticosteroids results in a more significant improvement in signs and symptoms of AD than with use of dupilumab in monotherapy. The vast majority of patients improves under dupilumab, and almost 40% of patients achieve clear or nearly clear skin. In addition to its effectiveness, dupilumab also has a favorable safety profile. Frequent adverse events reported in the clinical trials were mostly mild-to-moderate and included nasopharyngitis, upper respiratory tract infection, injection site reactions, and conjunctivitis.

CONCLUSIONS

In general, rates of adverse events occurred with similar frequency between the treatment and placebo groups. Conjunctivitis seems to be a dupilumab-specific side effect and so far has only been observed in atopic dermatitis patients (not in asthma or nasal polyposis). There were no major serious safety concerns identified in phase III clinical trials. Trials in the pediatric population are ongoing and are highly awaited.

Brain allopregnanolone induces marked scratching behaviour in diet-induced atopic dermatitis mouse model

Allopregnanolone (ALLO) is a neurosteroid produced in the brain, but so far, no study has explored its link with itching. Herein, we used a diet-induced atopic dermatitis mouse model to examine whether exogenously administered and endogenously produced ALLO contribute to inducing scratching. Systemic administration of ALLO elicited robust scratching in the atopic dermatitis model, while it did not affect spontaneous and pruritogen-induced scratching in normal mice. ALLO caused scratching when administered intracisternally, but not when administered intrathecally or intradermally, suggesting the involvement of supraspinal mechanisms. Pharmacological analyses suggested that both γ-aminobutyric acid type A receptor activation and serotonin type 3 receptor inhibition were involved in ALLO-induced scratching. We next examined whether endogenously produced ALLO is involved in ethanol-induced scratching in atopic dermatitis mice, because ethanol administration increases ALLO in rodent brain. Acute ethanol administration increased brain ALLO levels, which coincided with increased scratching. Pre-treatment with finasteride, a synthetic ALLO inhibitor, suppressed ethanol-induced scratching and ALLO production in the brain. Collectively, our results demonstrated for the first time that ALLO administration caused marked scratching in atopic dermatitis mice, and ethanol-induced scratching may be mediated through endogenously produced brain ALLO.

Potential Risks Related to Modulating Interleukin-13 and Interleukin-4 Signalling: A Systematic Review

Introduction

Interleukin-13 and interleukin-4 are type-II cytokines signalling through the shared type II interleukin-4 receptor. As a result of their structural similarity, interleukin-13 and interleukin-4 have overlapping functions in the mediation of type-II-driven diseases and are, therefore, promising targets of biologic drugs currently in development for the treatment of such diseases, including asthma and atopic dermatitis.

Objective

This systematic review was conducted to assess preclinical evidence of potential safety concerns related to blockade of interleukin-13 alone or interleukin-13 and interleukin-4 in combination.

Methods

We specifically examined risks related to infection, malignancy and the cardiovascular system. We systematically searched the BIOSIS, MEDLINE and EMBASE databases to identify preclinical studies published between January 2006 and October 2016 that addressed the effects of interleukin-13/interleukin-4 blockade and modulation on the risk of infection, malignancy and cardiovascular events. To provide a clinical context, we also performed a search for clinical trials targeting the interleukin-13/interleukin-4 pathways. Relevant data from preclinical and clinical trials were abstracted and presented descriptively.

Results

Aside from expected evidence that inhibition of interleukin-13 and interleukin-4 impaired host responses to helminth infections, we did not identify other preclinical evidence suggesting safety risks relating to infection, malignancy or cardiovascular events. We found no evidence in clinical trials suggesting serious safety concerns, i.e. increased risk for infections, malignancy or cardiovascular events from therapeutic modulation of the interleukin-13 pathway alone or the combined interleukin-13/interleukin-4 pathways.

Conclusions

Although our findings are reassuring, long-term safety assessments of biologics that target the interleukin-13/interleukin-4 pathways currently in clinical development are needed.

Electronic supplementary material

The online version of this article (10.1007/s40264-017-0636-9) contains supplementary material, which is available to authorized users.

Changing perspectives in atopic dermatitis

Atopic dermatitis (AD) is a multifaceted disease that involves a complex interplay between the skin and the immune system. The course of the disease depends strongly on the genetic background of the patient and on yet poorly-defined environmental factors. Changes in lifestyle could be behind the dramatic rise in the prevalence of AD across continents; including hygienic conditions, food, social habits, skin microbiome or exposure to a number of allergens. Although AD typically develops in childhood and disappears after a few years, in a relatively large number of patients it continues into adulthood. Adult AD can also appear de novo but it is often underdiagnosed and its treatment can be challenging. New, highly effective drugs are being developed to manage moderate and severe forms of the disease in adults. In this review, we highlight the most recent developments in diagnostic tools, current insights into the mechanistic basis of this disease, and therapeutic innovations.

Investigation of Immune-Regulatory Effects of Mageumsan Hot Spring via Protein Microarray In Vitro

Background

Empirical evidences for efficacy of hot spring (HS) water in inflammatory skin disorders have not been substantiated with sufficient, immunological “hard evidence”. Mageumsan HS water, characterized by its weakly-alkaline properties and low total dissolved solids content, has been known to alleviate various immune-inflammatory skin diseases, including atopic dermatitis (AD).

Objective

The trial attempted to quantitatively analyze in vitro expression levels of chemical mediators in cutaneous inflammation from HaCaT cell line treated with Mageumsan HS, and suggest the likely mode of action through which it exerts the apparent anti-inflammatory effects in AD.

Methods

Using membrane-based human antibody array kit, customized to include 30 different, keratinocyte-derived mediator proteins, their expression levels (including interleukin [IL]-1, IL-6, IL-8, thymic stromal lymphopoietin, thymus and activation-regulated chemokine, and granulocyte macrophage colony-stimulating factor) were assessed in vitro. Selected key proteins were further quantified with enzyme-linked immunosorbent assay.

Results

There was a clear pattern of overall suppression of the mediators, especially those noted for their pro-inflammatory role in AD (monocyte chemoattractant protein [MCP]-1, regulated on activation, normal T cell expressed and secreted, cutaneous T-cell-attracting chemokine, Eotaxin, and macrophage inflammatory protein-1α, etc.). Also, reduced expression of involucrin and cytokeratin 1 was also reduced in the HS-treated group.

Conclusion

The present study has shown that Mageumsan HS water may exert its effects on inflammatory skin disorders through regulation of proinflammatory cytokines. These evidences are to be supported with further future investigations to elucidate immunological mechanism behind these beneficial effects of HS water in the chronically inflamed skin of AD.

Effect of isoliquiritigenin for the treatment of atopic dermatitis-like skin lesions in mice

Atopic dermatitis (AD) is a common chronic inflammatory skin disease characterized with high heterogeneity. Recent studies have suggested that it is driven by both terminal keratinocyte differentiation defects and type 2 immune responses. The mainstay steroid topical therapy has severe side effect and new treatment is in demand. Isoliquiritigenin (ISLG) is a small phenolic bioactive molecule from licorice that has shown multiple pharmacological effects against cancer, inflammatory disorder, and cardiovascular diseases. ISLG was evaluated in AD-like lesion model induced by the repetitive application of 2,4-dinitrochlorobenzene (DNCB) in BALB/c mice. Overall symptom score, serological and molecular changes of the skin lesions were evaluated. ISLG could ameliorate the overall manifestation of AD-like symptoms including scratching behavior incidence and skin lesion severity. At blood level, ISLG significantly suppressed the DNCB-induced IgE and Th2 cytokines up-regulation. At skin lesion site, ISLG also inhibited DNCB-induced pro-inflammatory cytokines like TNF-α, IL-6 as well as IL-4 expressions. In a human monocyte model THP-1, ISLG suppressed the up-regulation of CD86 and CD54 and abolished the DNCB-induced p38-α and ERK activation, suggesting a molecular mechanism for ISLG therapy. This study indicated that ISLG could be a potential therapeutic agent for the treatment of AD.

New and emerging targeted systemic therapies: a new era for atopic dermatitis

PURPOSE

This is a review of emerging targeted, systemic therapies for atopic dermatitis (AD). The information presented aims to provide dermatologists with updated therapeutic options, stimulate academic interest, and spark future research.

MATERIAL AND METHODS

Extensive search of ClinicalTrials.gov, the National Eczema Association, and PubMed was performed for clinical trials examining the effect of emerging targeted, systemic therapies in patients with AD. Results were included if they demonstrated efficacy in reversing AD symptoms. Studies that did not demonstrate clinical benefit were excluded.

RESULTS

A number of emerging systemic agents targeting specific mediators involved in the pathogenesis of AD were found. These targets include IL-4, IL-13, IgE, B-cells, IL-5, IL-31, JAK-STAT, SYK, IL-6, PDE-4, IL-12, IL-17, IL-23, IL-22, H4R, NKR1, κOR, TSLP, PPAR-γ, and DGLA. Treatment of AD patients with these therapies has, in many cases, led to statistically significant improvements in clinical severity scores and patient-reported outcomes.

CONCLUSIONS

While multiple agents have demonstrated efficacy, only dupilumab is currently approved for adults with AD. Large-scale, randomized, placebo-controlled, double-blind trials, especially in children, are needed. As we enter the dawn of targeted therapy for AD, a comprehensive clinical trial registry is needed to facilitate data pooling and comparison among international registries.

Cellular and molecular immunologic mechanisms in patients with atopic dermatitis

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

Oral administration of lactobacilli isolated from Jeotgal, a salted fermented seafood, inhibits the development of 2,4-dinitrofluorobenzene-induced atopic dermatitis in mice

Certain strains of lactobacilli have been reported to exert favorable effects on atopic dermatitis (AD). Jeotgal, a traditional Korean food, is a salted fermented seafood known to harbor many lactic acid bacteria. In the present study, two novel lactobacillus strains were isolated from Jeotgal, and their anti-AD effects were investigated. Lactobacilli isolated from Jeotgal were identified, according to conjugated linoleic acid-producing activity, as Lactobacillus plantarum (JBCC105645 and JBCC105683). AD-like skin lesions were induced in BALB/c mice using dinitrofluorobenzene (DNFB). Ear swelling, histological analysis and serum immunoglobulin E (IgE) levels in mice were evaluated to investigate the anti-AD effects of lactobacilli. Cytokine production of ex vivo cluster of differentiation (CD)4⁺ T cells, and interleukin (IL)-12 production of in vitro macrophages were also evaluated to establish a putative mechanism of the action of lactobacilli. Administration of JBCC105645 or JBCC105683 suppressed ear swelling and serum IgE levels in DNFB-treated mice (P<0.05). Notably, JBCC105645 was more effective than JBCC105683 (P<0.05). Treatment with the lactobacilli also induced a significant decrease in IL-4 production with concomitant increase in interferon (IFN)-γ production in DNFB-exposed CD4⁺ T cells, and an increase in IL-12 production in macrophages (P<0.05). Taken together, the lactobacilli isolated from Jeotgal may suppress the development of AD-like skin inflammation in mice by modulating IL-4 and IFN-γ production in CD4⁺ T cells, presumably via enhancing IL-12 production by macrophages.

Assessment of Neutrophil-to-Lymphocyte Ratio and Platelet-to-Lymphocyte Ratio in Atopic Dermatitis Patients

BACKGROUND To develop new strategies for identifying atopic dermatitis patients, a better understanding of the signs for chronic inflammatory status is needed. This study was designed to investigate whether neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) are related to the severity of atopic dermatitis (AD) assessed by the Scoring Atopic Dermatitis (SCORAD) index. MATERIAL AND METHODS A retrospective study involving 80 AD patients and 45 healthy control subjects was performed. NLR, PLR, and the number of peripheral blood eosinophils were compared between AD patients and healthy controls, and correlations between these indexes and clinical characteristics were analyzed. RESULTS NLR, PLR, and eosinophils in AD patients were all significantly higher than in healthy individuals. Among AD patients, NLR (p<0.001) and PLR (p<0.001), as contrasted with eosinophils (p=0.146), were correlated positively with SCORAD index. Additionally, an NLR level of 1.75 was determined as the predictive cut-off value of severe AD (SCORAD ≥51) (sensitivity 94.7%, specificity 58.6%, the area under the receiver-operating characteristic curve (AUROC) 0.778, p=0.001). For eosinophils, the sensitivity and specificity were 78.9% and 62.1%, respectively, and the AUROC was only 0.685 (p=0.032) in predicting high SCORAD. CONCLUSIONS NLR and PLR reflect inflammatory response and disease severity in AD patients.

Dupilumab in the treatment of moderate-to-severe atopic dermatitis

INTRODUCTION

Atopic dermatitis is a common inflammatory skin disease with an increasing prevalence. Treatment of patients suffering from mild or moderate disease includes the use of emollients and topical glucocorticoids or topical calcineurin inhibitors. Patients with chronic and severe atopic dermatitis where topical therapy is usually insufficient require the use of systemic immunosuppressive drugs, which is often limited due to toxicity and severe adverse effects. Areas covered: This review summarizes the literature on the mechanism of action, clinical efficacy and safety of dupilumab, a monoclonal antibody that targets the α-subunit of the interleukin-4 receptor (IL-4Rα) leading to the inhibition of both the IL-4 and IL-13 pathways. A literature search was performed on Pubmed and ClinicalTrials.gov using key words 'dupilumab', 'REGN668', 'IL-4'/'IL-13' and 'atopic dermatitis'. Expert commentary: Dupilumab offers an innovative therapeutic approach for moderate-to-severe atopic dermatitis. It is not approved for clinical use in any country yet; however, due to its excellent clinical efficacy and a favorable safety profile, dupilumab may revolutionize the treatment of moderate-to-severe atopic dermatitis in the next upcoming years.

The adaptive immune system in atopic dermatitis and implications on therapy

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