Atopic dermatitis endotypes and implications for targeted therapeutics

From Emollients to Biologicals: Targeting Atopic Dermatitis

Atopic dermatitis (AD) is the most common chronic inflammatory skin disease and significantly impacts patients' lives, particularly in its severe forms. AD clinical presentation varies over the course of the disease, throughout different age groups, and across ethnicities. AD is characterized by a spectrum of clinical phenotypes as well as endotypes. Starting from the current description of AD pathogenesis, this review explores the rationale of approved AD therapies from emollients to biologicals and introduces novel promising drugs.

Effects of an emollient application on newborn skin from birth for prevention of atopic dermatitis: a randomized controlled study in Thai neonates

BACKGROUND

Enhancing the skin barrier in high-risk neonates by daily use of emollients during infancy might prevent atopic dermatitis (AD); however, there have been no studies on this topic in a country with a tropical climate. Climate may affect the results of the use of emollients in neonates for AD prevention and possible adverse cutaneous eruptions.

OBJECTIVES

To test the hypothesis that emollients used during infancy can prevent AD in high-risk neonates in a country with a tropical climate and to evaluate other possible adverse cutaneous eruptions in this population.

METHODS

This was a randomized controlled study in a tertiary care hospital with a 6 months' duration. Eligible neonates were randomly assigned to receive either emollient and skincare advice (emollient group) or skincare advice only (control group). The intervention was started within 3 weeks of birth.

RESULTS

The emollient group showed a significant reduction in the cumulative incidence of AD at 6 months (relative risk, 0.39; 95% CI 0.24-0.64; P < 0.001). The emollient group started to develop AD later and had a lower severity of AD than the control group (P < 0.001). Compared to moderate adherence, low adherence to emollient application was associated with a lower number of patients with AD (P = 0.008). Potentially emollient-related cutaneous eruptions, such as miliaria, and suspected cutaneous infections, such as impetigo, were more frequent in the emollient group. Exposure to passive smoking showed a significant difference in the development of AD compared to non-smoking exposure, both during pregnancy and after the child's birth (P < 0.001).

CONCLUSIONS

This study suggests that, in a tropical climate, emollient applied to the skin of at-risk neonates on an 'as needed' basis (depending on environmental factors, level of skin dryness), rather than on a 'daily basis', can provide a substantial benefit for AD prevention.

Transient and reversible reduction of stratum corneum filaggrin degradation products after allergen challenge in experimentally mite-sensitised atopic dogs

BACKGROUND

A defective skin barrier occurs in dogs with atopic dermatitis, and there is controversy over whether this defect pre-exists, or is secondary to allergic inflammation.

OBJECTIVES

To study if an allergen challenge decreases the natural moisturising factor (NMF), which contains the main filaggrin degradation products.

ANIMALS

Four house dust mite (HDM)-sensitised adult atopic dogs from a research colony.

METHODS AND MATERIALS

Dogs were challenged epicutaneously with HDMs on the right lateral abdomen while the left thorax served as control. We swabbed the skin surface before, and at days (D)1, D2, D3, D7 and D28 after challenge, on both selected sites; swabs were soaked in detergent and frozen until assayed. The NMF components were measured by liquid chromatography-tandem mass spectrometry (LC/MS-MS).

RESULTS

The allergen challenge induced moderate skin lesions at the application sites, and also mild erythema at the control areas. The allergen provocation led to significant decreases in the total NMF and its components trans-urocanic acid (t-UCA), pyrrolidone carboxylic acid (PCA) and serine on both sites. Lesion scores abated by D7 and the NMF concentrations had re-increased by D28. Skin lesion scores correlated negatively with the total NMF, t-UCA and PCA concentrations.

CONCLUSIONS AND CLINICAL IMPORTANCE

In this experimental model, a single epicutaneous allergen challenge led to a transient and reversible decrease in skin surface NMF and its components, and concentrations were negatively correlated with skin lesion scores. These observations suggest that some of the skin barrier anomalies seen in atopic dogs likely develop secondarily to the underlying cutaneous allergic inflammation.

Achieving Precision Medicine in Allergic Disease: Progress and Challenges

Allergic diseases (atopic dermatitis, food allergy, eosinophilic esophagitis, asthma and allergic rhinitis), perhaps more than many other traditionally grouped disorders, share several overlapping inflammatory pathways and risk factors, though we are still beginning to understand how the relevant patient and environmental factors uniquely shape each disease. Precision medicine is the concept of applying multiple levels of patient-specific data to tailor diagnoses and available treatments to the individual; ideally, a patient receives the right intervention at the right time, in order to maximize effectiveness but minimize morbidity, mortality and cost. While precision medicine in allergy is in its infancy, the recent success of biologics, development of tools focused on large data set integration and improved sampling methods are encouraging and demonstrates the utility of refining our understanding of allergic endotypes to improve therapies. Some of the biggest challenges to achieving precision medicine in allergy are characterizing allergic endotypes, understanding allergic multimorbidity relationships, contextualizing the impact of environmental exposures (the “exposome”) and ancestry/genetic risks, achieving actionable multi-omics integration, and using this information to develop adequately powered patient cohorts and refined clinical trials. In this paper, we highlight several recently developed tools and methods showing promise to realize the aspirational potential of precision medicine in allergic disease. We also outline current challenges, including exposome sampling and building the “knowledge network” with multi-omics integration.

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.

Immune and barrier characterization of atopic dermatitis skin phenotype in Tanzanian patients

BACKGROUND

Atopic dermatitis (AD) is a common disease, with particularly high prevalence found in Africa. It is increasingly recognized that patients with AD of different ethnic backgrounds have unique molecular signatures in the skin, potentially accounting for treatment response variations. Nevertheless, the skin profile of patients with AD from Africa is unknown, hindering development of new treatments targeted to this patient population.

OBJECTIVE

To characterize the skin profile of patients with AD from Africa.

METHODS

Gene expression studies, including RNA sequencing (using threshold of fold change of >2 and false discovery rate of <0.05) and real-time polymerase chain reaction, were performed on skin biopsies of Tanzanian patients with moderate-to-severe AD and controls.

RESULTS

Tanzanian AD skin presented robust up-regulations of multiple key mediators of both T helper 2 (TH2) (interleukin 13 [IL-13], IL-10, IL-4R, CCL13,CCL17,CCL18,CCL26) and TH22 (IL22, S100As) pathways. Markers related to TH17 and IL-23 (IL-17A, IL-23A, IL-12, PI3, DEFB4B) and TH1 (interferon gamma, CXCL9,CXCL10,CXCL11) were also significantly overexpressed in AD tissues (FDR<.05), albeit to a lesser extent. IL-36 isoforms revealed substantial up-regulations in African skin. The barrier fingerprint of Tanzanian AD revealed no suppression of hallmark epidermal barrier differentiation genes, such as filaggrin, loricrin, and periplakin, with robust attenuation of lipid metabolism genes (ie, AWAT1).

CONCLUSION

The skin phenotype of Tanzanian patients with AD is consistent with that of African Americans, exhibiting dominant TH2 and TH22 skewing, minimal dysregulation of terminal differentiation, and even broader attenuation of lipid metabolism-related products. These data highlight the unique characteristic of AD in Black individuals and the need to develop unique treatments targeting patients with AD from these underrepresented populations.

JAK inhibitors in the treatment of atopic dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disorder associated with heterogenous presentation and often immense patient burden. Safe, targeted treatment options are currently limited. This focused review of the published literature, including clinical trial results, case reports, and abstracts, as well as presentations from scientific meetings and data from industry press releases, describes the use of topical and systemic Janus kinase (JAK) inhibitors in the treatment of AD. New topical JAK inhibitors include ruxolitinib (JAK1/2) and delgocitinib (pan-JAK). Ruxolitinib cream met all primary and secondary endpoints in phase 3 clinical trials for mild-to-moderate AD with minimal treatment-emergent adverse events. Delgocitinib ointment was recently approved in Japan for pediatric and adult AD. Oral JAK inhibitors include baricitinib (JAK1/2), abrocitinib (JAK1-selective), and upadacitinib (JAK1-selective). All 3 met primary and secondary endpoints across numerous trials for moderate-to-severe AD. Treatment-emergent adverse events were mainly mild to moderate and included acne, nausea, headache, upper respiratory tract infection, and to a lesser degree, herpes infection and selected laboratory abnormalities. JAK inhibitors hold great promise as the next generation of targeted AD therapy. While their outstanding efficacy is balanced by a favorable safety profile in clinical trials, real-world data are needed to better understand long-term safety, durability, and treatment success.

Dupilumab pharmacokinetics in Chinese healthy subjects and patients with atopic dermatitis: Results of two randomized, double-blind, placebo-controlled studies

BACKGROUND

Dupilumab, a fully human monoclonal antibody targeting IL-4Rα, has demonstrated rapid and sustained improvements in clinical outcomes in patients with atopic dermatitis (AD), asthma, and chronic rhinosinusitis with nasal polyps.

METHODS

In a phase 1, double-blind, ascending-dose study, 30 healthy Chinese adults were randomized to single subcutaneous doses of dupilumab 200, 300, 600 mg, or placebo. In a phase 3, double-blind study, 165 Chinese adults with AD were randomized to dupilumab 300 mg or placebo every 2 weeks.

RESULTS

Following single doses of dupilumab 200, 300, and 600 mg in the phase 1 study, mean serum maximum concentrations (C_max) were 25.4 ± 4.0, 37.2 ± 14.5, and 77.3 ± 19.0 mg/L, respectively. For a 1.5-fold increase in dupilumab dose, 1.31-, 1.73-, and 1.66-fold increases in C_max, area under the curve to real time (AUC_last), and extrapolated to infinity (AUC) were observed, respectively, while a 2-fold dose increase resulted in 2.17-, 2.81-, and 2.80-fold increases, respectively. In the phase 3 study, mean dupilumab trough concentrations were 78.8 ± 32.0 and 86.4 ± 33.6 mg/L at weeks 12 and 16, respectively.

CONCLUSIONS

C_max increased approximately proportionally to dose, while AUC and AUC_last increased greater than proportionally. Dupilumab pharmacokinetics were generally comparable between Chinese and non-Asian healthy subjects (single dose) and between Chinese and non-Asian AD patients (repeated doses), with differences accounted for by body weight. As differences in exposure by weight are unlikely to be clinically relevant based on late-stage study results, no dose adjustment by ethnic origin or weight is required.

Safety of Janus kinase (JAK) inhibitors in the short-term treatment of atopic dermatitis

Atopic dermatitis (AD) is a chronic heterogeneous condition characterized by erythematous, pruritic, and inflamed skin. Janus kinase (JAK) inhibitors are a new class of drugs that target proteins in the Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathway. These drugs can be administered orally or topically to inhibit signaling of the JAK-STAT pathway and minimize the production of proinflammatory cytokines. The efficacy and safety of JAK inhibitors have been investigated in phase 2 and 3 clinical trials for AD. The safety of new medications, which are immunosuppressive by nature, is of utmost concern for the prescriber and patient alike. Herein we summarize the safety results of clinical trials using oral abrocitinib, upadacitinib, and baricitinib, as well as topical ruxolitinib and delgocitinib for the treatment of AD. The most prevalent (2-5% occurrence rate) treatment-emergent adverse events from oral JAK inhibitor use in AD were nausea, upper respiratory tract infection, headache, herpes zoster, herpes simplex, acne, increased blood creatine phosphokinase levels, and decreased platelet counts. Topical JAK inhibitors were not associated with systemic effects. All studies reported that JAK inhibitors were well tolerated in patients with AD in comparison with the control group. While the use of JAK inhibitors in patients suffering from AD is very promising, trials reported to date are of short duration (maximum 16 weeks), and more information on the long-term safety of these novel agents is required.

Atopic dermatitis: an expanding therapeutic pipeline for a complex disease

Atopic dermatitis (AD) is a common chronic inflammatory skin disease with a complex pathophysiology that underlies a wide spectrum of clinical phenotypes. AD remains challenging to treat owing to the limited response to available therapies. However, recent advances in understanding of disease mechanisms have led to the discovery of novel potential therapeutic targets and drug candidates. In addition to regulatory approval for the IL-4Ra inhibitor dupilumab, the anti-IL-13 inhibitor tralokinumab and the JAK1/2 inhibitor baricitinib in Europe, there are now more than 70 new compounds in development. This Review assesses the various strategies and novel agents currently being investigated for AD and highlights the potential for a precision medicine approach to enable prevention and more effective long-term control of this complex disease.

Recent advances in understanding of the complex phenotype and mechanisms underlying atopic dermatitis (AD) have revealed multiple new potential targets for pharmacological intervention. Here, Bieber reviews therapeutic strategies and assesses the expanding pipeline for the therapy of AD, highlighting the potential for a precision medicine approach to the management of this complex disorder.

Optimization of approaches to the management of adult patients with severe atopic dermatitis: analysis of real clinical practice outcomes

Atopic dermatitis (AD) is a multifactorial genetically determined immune-mediated skin disease. It is difficult to treat and significantly affects patients quality of life. The development of an integrated approach focusing on atopic multimorbidity, implementation of validated control tools and distinction of clinical parameters specific for different phenotypes of severe forms of disease is especially relevant to patients resistant to standard therapy techniques. Dupilumab, a biologic, is approved for the treatment of the resistant group of patients with moderate to severe AD in the Russian Federation. Dupilumab inhibits the functions of two key cytokines of T2-mediated inflammation IL-4 and IL-13. The article presents personal experience of the authors concerning individual approach to the choice of therapy for the management of this cohort of patients in routine clinical practice. The disease aggravating criteria were determined, which are fundamental for the formation of individual patient portrait for the biologic (dupilumab) treatment for severe AD.

The Influence of Microbiome Dysbiosis and Bacterial Biofilms on Epidermal Barrier Function in Atopic Dermatitis-An Update

Atopic dermatitis (AD) is a common inflammatory dermatosis affecting up to 30% of children and 10% of adults worldwide. AD is primarily driven by an epidermal barrier defect which triggers immune dysregulation within the skin. According to recent research such phenomena are closely related to the microbial dysbiosis of the skin. There is growing evidence that cutaneous microbiota and bacterial biofilms negatively affect skin barrier function, contributing to the onset and exacerbation of AD. This review summarizes the latest data on the mechanisms leading to microbiome dysbiosis and biofilm formation in AD, and the influence of these phenomena on skin barrier function.

Whole genome sequencing identifies novel genetic mutations in patients with eczema herpeticum

BACKGROUND

Eczema herpeticum (EH) is a rare complication of atopic dermatitis (AD) caused by disseminated herpes simplex virus (HSV) infection. The role of rare and/or deleterious genetic variants in disease etiology is largely unknown. This study aimed to identify genes that harbor damaging genetic variants associated with HSV infection in AD with a history of recurrent eczema herpeticum (ADEH+).

METHODS

Whole genome sequencing (WGS) was performed on 49 recurrent ADEH+ (≥3 EH episodes), 491 AD without a history of eczema herpeticum (ADEH-) and 237 non-atopic control (NA) subjects. Variants were annotated, and a gene-based approach (SKAT-O) was used to identify genes harboring damaging genetic variants associated with ADEH+. Genes identified through WGS were studied for effects on HSV responses and keratinocyte differentiation.

RESULTS

Eight genes were identified in the comparison of recurrent ADEH+to ADEH-and NA subjects: SIDT2, CLEC7A, GSTZ1, TPSG1, SP110, RBBP8NL, TRIM15, and FRMD3. Silencing SIDT2 and RBBP8NL in normal human primary keratinocytes (NHPKs) led to significantly increased HSV-1 replication. SIDT2-silenced NHPKs had decreased gene expression of IFNk and IL1b in response to HSV-1 infection. RBBP8NL-silenced NHPKs had decreased gene expression of IFNk, but increased IL1b. Additionally, silencing SIDT2 and RBBP8NL also inhibited gene expression of keratinocyte differentiation markers keratin 10 (KRT10) and loricrin (LOR).

CONCLUSION

SIDT2 and RBBP8NL participate in keratinocyte's response to HSV-1 infection. SIDT2 and RBBP8NL also regulate expression of keratinocyte differentiation genes of KRT10 and LOR.

Human leukocyte antigen class-I variation is associated with atopic dermatitis: A case-control study

Atopic dermatitis (AD) is a common immune-medicated skin disease. Previous studies have explored the relationship between Human Leukocyte Antigen (HLA) allelic variation and AD with conflicting results. The aim was to examine HLA Class I genetic variation, specifically peptide binding groove variation, and associations with AD. A case-control study was designed to evaluate HLA class I allelic variation and binding pocket polymorphisms, using next generation sequencing on 464 subjects with AD and 388 without AD. Logistic regression was used to evaluate associations with AD by estimating odds ratios (95% confidence intervals). Significant associations were noted with susceptibility to AD (B*53:01) and protection from AD (A*01:01, A*02:01, B*07:02 and C*07:02). Evaluation of polymorphic residues in Class I binding pockets revealed six amino acid residues conferring protection against AD: A9F (HLA-A, position 9, phenylalanine) [pocket B/C], A97I [pocket C/E], A152V [pocket E], A156R [pocket D/E], B163E [pocket A] and C116S [pocket F]. These findings demonstrate that specific HLA class I components are associated with susceptibility or protection from AD. Individual amino acid residues are relevant to protection from AD and set the foundation for evaluating potential HLA Class I molecules in complex with peptides/antigens that may initiate or interfere with T-cell responses.

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.

Lycoperoside H, a steroidal alkaloid saponin in tomato seeds, ameliorates atopic dermatitis-like symptoms in IL-33 transgenic mice

Tomato seeds contain steroidal saponins called lycoperosides. However, it currently remains unclear whether lycoperosides exert anti-inflammatory or anti-allergic effects. Therefore, we herein investigated the effects of tomato seed extract (TSE) and lycoperoside H (LH) in Interleukin (IL)-33 transgenic mice. TSE (500 mg/kg) or LH (10 mg/kg) was orally administered once a day for 101 days and then evaluated mouse behavior, skin symptoms, and blood and skin inflammatory cytokines. TSE slightly suppressed scratching behavior, while TSE and LH both increased locomotive activity. LH also significantly suppressed inflammation scores in the limbs, and TSE and LH reduced transepidermal water loss. Epidermal hyperplasia and the accumulation of eosinophils and mast cells were decreased by TSE and LH. Skin Th2/Th1 cytokine ratio and serum IgE concentrations were significantly reduced by TSE and LH. The present results suggest that the oral administration of LH derived from tomato seeds effectively ameliorates the symptoms of atopic dermatitis. PRACTICAL APPLICATIONS: It has been reported that tomato seeds contain steroidal saponins, lycoperosides, though the effects of lycoperosides on anti-inflammatory or anti-allergic have not yet been revealed. In this study, we demonstrated that the oral administration of lycoperoside H derived from tomato seeds suppressed atopic dermatitis symptoms in IL-33 transgenic mice.

Atopic Eczema: Pathophysiological Findings as the Beginning of a New Era of Therapeutic Options

Atopic eczema (AE) is a chronic inflammatory disease hallmarked by intense pruritus and eczematous lesions. It depicts one of the most common skin diseases affecting a major part of children and several percentages of adults.Both pathogenesis and pathophysiology are based on complex orchestrated interactions of skin barrier defects, immunological changes, the environment, and an abundance of other contributing factors. Frequently, AE displays the starting point for other allergic diseases such as allergic asthma and rhinoconjunctivitis. Additionally, the risk of developing food allergy is increased. Furthermore, the disease is accompanied by a susceptibility to bacterial, fungal, and viral infections. The development of new therapies received great impetus by an ample research of the pathophysiological mechanisms, leading to a new era in the treatment of severe atopic eczema due to targeted treatments, e.g. the IL-4R alpha specific monoclonal antibody dupilumab.This article provides an overview of the causative and pathophysiological characteristics, the clinical and diagnostic aspects as well as current and future therapeutical possibilities focusing allergic aspects contributing to the course of the disease.

Epigenetic Mechanisms in Allergy Development and Prevention

There has been a substantial increase in the incidence and the prevalence of allergic disorders in the recent decades, which seems to be related to rapid environmental and lifestyle changes, such as higher exposure to factors thought to exert pro-allergic effects but less contact with factors known to be associated with protection against the development of allergies. Pollution is the most remarkable example of the former, while less contact with microorganisms, lower proportion of unprocessed natural products in diet, and others resulting from urbanization and westernization of the lifestyle exemplify the latter. It is strongly believed that the effects of environmental factors on allergy susceptibility and development are mediated by epigenetic mechanisms, i.e. biologically relevant biochemical changes of the chromatin carrying transcriptionally-relevant information but not affecting the nucleotide sequence of the genome. Classical epigenetic mechanisms include DNA methylation and histone modifications, for instance acetylation or methylation. In addition, microRNA controls gene expression at the mRNA level. Such epigenetic mechanisms are involved in crucial regulatory processes in cells playing a pivotal role in allergies. Those include centrally managing cells, such as T lymphocytes, as well as specific structural and effector cells in the affected organs, responsible for the local clinical presentation of allergy, e.g. epithelial or airway smooth muscle cells in asthma. Considering that allergic disorders possess multiple clinical (phenotypes) and mechanistic (endotypes) forms, targeted, stratified treatment strategies based on detailed clinical and molecular diagnostics are required. Since conventional diagnostic or therapeutic approaches do not suffice, this gap could possibly be filled out by epigenetic approaches.

Atopic Dermatitis in Domestic Animals: What Our Current Understanding Is and How This Applies to Clinical Practice

Atopic dermatitis is a clinical syndrome that affects both people and animals. Dogs closely mimic the complexity of the human skin disease, and much progress has been made in recent years in terms of our understanding of the role of skin impairment and the identification of new treatments. Cats and horses also develop atopic syndromes which include both cutaneous and respiratory signs, yet studies in these species are lagging. It is now recognized that atopic dermatitis is not a single disease but a multifaceted clinical syndrome with different pathways in various subgroups of patients. Appreciating this complexity is clinically relevant as we develop more targeted treatments which may work well in some patients but not in others. Different phenotypes of atopic dermatitis have been described in dogs, and it is possible that phenotypes related to breed and age may exist in other animals similar to how they are described in people. The awareness of different mechanisms of disease leads to the desire to correlate different phenotypes with specific biomarkers and responses to treatment. In this review, the current understanding and updated information on atopic syndrome in animals are described, highlighting opportunities for further studies in the future.

Delgocitinib ointment in pediatric patients with atopic dermatitis: A phase 3, randomized, double-blind, vehicle-controlled study and a subsequent open-label, long-term study

BACKGROUND

Delgocitinib 0.5% ointment, a topical Janus kinase inhibitor, has been approved in Japan for adult patients with atopic dermatitis (AD).

OBJECTIVE

To evaluate the efficacy and safety of delgocitinib ointment in pediatric patients with AD.

METHODS

Part 1 of this study was a 4-week double-blind period in which Japanese patients aged 2 through 15 years were randomized in a 1:1 ratio to delgocitinib 0.25% ointment or vehicle ointment. Part 2 was a 52-week extension period. Eligible patients entered part 2 to receive 0.25% or 0.5% delgocitinib ointment.

RESULTS

At the initiation of the study, approximately half of the patients had moderate AD. At the end of treatment in part 1, the least-squares mean percent change from baseline in modified Eczema Area and Severity Index score, the primary efficacy endpoint, was significantly greater for delgocitinib ointment than for vehicle (-39.3% vs +10.9%, P < .001). In part 2, improvements in AD were also seen through week 56. Most adverse events were mild and unrelated to delgocitinib across the study periods.

LIMITATIONS

Only Japanese patients were included. In part 2, no control group was included and rescue therapy was allowed.

CONCLUSION

Delgocitinib ointment was effective and well tolerated when applied to Japanese pediatric patients with AD for up to 56 weeks.

New Treatments for Atopic Dermatitis Targeting Skin Barrier Repair via the Regulation of FLG Expression

Atopic dermatitis (AD) is one of the most common chronic, inflammatory skin disorders with a complex etiology and a broad spectrum of clinical phenotypes. Despite its high prevalence and effect on the quality of life, safe and effective systemic therapies approved for long-term management of AD are limited. A better understanding of the pathogenesis of atopic dermatitis in recent years has contributed to the development of new therapeutic approaches that target specific pathophysiological pathways. Skin barrier dysfunction and immunological abnormalities are critical in the pathogenesis of AD. Recently, the importance of the downregulation of epidermal differentiation complex (EDC) molecules caused by external and internal stimuli has been extensively emphasized. The purpose of this review is to discuss the innovations in the therapy of atopic dermatitis, including biologics, small molecule therapies, and other drugs by highlighting regulatory mechanisms of skin barrier-related molecules, such as filaggrin (FLG) as a crucial pathway implicated in AD pathogenesis.

Proteomic signatures of inflammatory skin diseases: a focus on atopic dermatitis

Introduction: Atopic dermatitis (AD) is a chronic inflammatory skin condition characterized by cutaneous and systemic inflammation and barrier abnormalities. Over the past few decades, proteomic studies have been increasingly applied to AD research to compliment transcriptomic evaluations. Proteomic analyses helped identify new biomarkers of AD, allowing investigation of both the cutaneous AD profile and the systemic inflammation associated with the disease.Areas covered: This review discusses key studies that utilized various proteomic technologies to analyze AD skin and/or blood, which facilitated discovery of biomarkers related to pathogenesis, disease severity, systemic inflammation, and therapeutic response. Moreover, this review summarizes proteomic studies that helped define various AD endotypes/phenotypes. A literature search was conducted by querying Scopus, Google Scholar, PubMed/Medline, and Clinicaltrials.gov up to January 2021.Expert opinion: Use of proteomics in AD has allowed for identification of novel AD-related protein biomarkers. This approach continues to evolve and is becoming increasingly common for the study of AD, in conjunction with other -omics platforms, as proteomics shifts to quicker and more sensitive methods for detection of potential protein biomarkers. Although many biomarkers have been identified thus far, future larger studies are necessary to further correlate these markers with clinical parameters.

Current Insights into Immunology and Novel Therapeutics of Atopic Dermatitis

Atopic dermatitis (AD) is one of the most prevalent inflammatory disease among non-fatal skin diseases, affecting up to one fifth of the population in developed countries. AD is characterized by recurrent pruritic and localized eczema with seasonal fluctuations. AD initializes the phenomenon of atopic march, during which infant AD patients are predisposed to progressive secondary allergies such as allergic rhinitis, asthma, and food allergies. The pathophysiology of AD is complex; onset of the disease is caused by several factors, including strong genetic predisposition, disrupted epidermal barrier, and immune dysregulation. AD was initially characterized by defects in the innate immune system and a vigorous skewed adaptive Th2 response to environmental agents; there are compelling evidences that the disorder involves multiple immune pathways. Symptomatic palliative treatment is the only strategy to manage the disease and restore skin integrity. Researchers are trying to more precisely define the contribution of different AD genotypes and elucidate the role of various immune axes. In this review, we have summarized the current knowledge about the roles of innate and adaptive immune responsive cells in AD. In addition, current and novel treatment strategies for the management of AD are comprehensively described, including some ongoing clinical trials and promising therapeutic agents. This information will provide an asset towards identifying personalized targets for better therapeutic outcomes.

Cytokine RNA In Situ Hybridization Permits Individualized Molecular Phenotyping in Biopsies of Psoriasis and Atopic Dermatitis

Detection of individual cytokines in routine biopsies from patients with inflammatory skin diseases has the potential to personalize diagnosis and treatment selection, but this approach has been limited by technical feasibility. We evaluate whether a chromogen-based RNA in situ hybridization approach can be used to detect druggable cytokines in psoriasis and atopic dermatitis. A series of psoriasis (n = 20) and atopic dermatitis (n = 26) biopsies were stained using RNA in situ hybridization for IL4, IL12B (IL-12/23 p40), IL13, IL17A, IL17F, IL22, IL23A (IL-23 p19), IL31, and TNF (TNF-α). NOS2 and IFNG, canonical psoriasis biomarkers, were also included. All 20 of the psoriasis cases were positive for IL17A, which tended to be the predominant cytokine, although some cases had relatively higher levels of IL12B, IL17F, or IL23A. The majority of cytokine expression in psoriasis was epidermal. A total of 22 of 26 atopic dermatitis cases were positive for IL13, also at varying levels; a subset of cases had significant IL4, IL22, or IL31 expression. Patterns were validated in independent bulk RNA-sequencing and single-cell RNA-sequencing datasets. Overall, RNA in situ hybridization for cytokines appears highly specific with virtually no background staining and may allow for individualized evaluation of treatment-relevant cytokine targets in biopsies from patients with inflammatory skin disorders.

Spotlight on microRNAs in allergy and asthma

In past 10 years, microRNAs (miRNAs) have gained scientific attention due to their importance in the pathophysiology of allergic diseases and their potential as biomarkers in liquid biopsies. They act as master post‐transcriptional regulators that control most cellular processes. As one miRNA can target several mRNAs, often within the same pathway, dysregulated expression of miRNAs may alter particular cellular responses and contribute, or lead, to the development of various diseases. In this review, we give an overview of the current research on miRNAs in allergic diseases, including atopic dermatitis, allergic rhinitis, and asthma. Specifically, we discuss how individual miRNAs function in the regulation of immune responses in epithelial cells and specialized immune cells in response to different environmental factors and respiratory viruses. In addition, we review insights obtained from experiments with murine models of allergic airway and skin inflammation and offer an overview of studies focusing on miRNA discovery using profiling techniques and bioinformatic modeling of the network effect of multiple miRNAs. In conclusion, we highlight the importance of research into miRNA function in allergy and asthma to improve our knowledge of the molecular mechanisms involved in the pathogenesis of this heterogeneous group of diseases.

New Biologics for the Treatment of Atopic Dermatitis: Analysis of Efficacy, Safety, and Paradoxical Atopic Dermatitis Acceleration

Atopic dermatitis (AD) is a chronic, inflammatory skin disease with an eczematous rash and itching. Due to undesired adverse effects of traditional systemic treatment, there is still an unmet need for safe and effective long-term therapy for refractory AD. As our understanding of the pathogenesis underlying AD grows, novel treatments targeting specific molecules have been developed. Here, we discuss the efficacy and safety profiles of these drugs in recent clinical trials. Among their adverse effects, of particular note is AD acceleration. Although there is still debate about whether certain adverse reactions can be said to be paradoxical adverse events (PAEs), a wide range of PAEs have been reported during biological treatment for chronic immune-mediated diseases. Close surveillance of novel biologics is crucial to detect new undescribed paradoxical reactions and to shed light on the convoluted pathogenesis of AD.

Transcriptomic analysis of atopic dermatitis in African Americans is characterized by Th2/Th17-centered cutaneous immune activation

Atopic dermatitis (AD) often presents more severely in African Americans (AAs) and with greater involvement of extensor areas. To investigate immune signatures of AD in AAs with moderate to severe pruritus, lesional and non-lesional punch biopsies were taken from AA patients along with age-, race-, and sex-matched controls. Histology of lesional skin showed psoriasiform dermatitis and spongiotic dermatitis, suggesting both Th2 and Th17 activity. Gene Set Variation Analysis showed upregulation of Th2 and Th17 pathways in both lesional versus non-lesional and lesional versus control (p < 0.01), while Th1 and Th22 upregulation were observed in lesional versus control (p < 0.05). Evidence for a broad immune signature also was supported by upregulated Th1 and Th22 pathways, and clinically may represent greater severity of AD in AA. Furthermore, population-level analysis of data from TriNetX, a global federated health research network, revealed that AA AD patients had higher values for CRP, ferritin, and blood eosinophils compared to age-, sex-, and race-matched controls as well as white AD patients, suggesting broad systemic inflammation. Therefore, AA AD patients may feature broader immune activation than previously thought and may derive benefit from systemic immunomodulating therapies that modulate key drivers of multiple immune pathways.

Emerging Systemic Therapeutic Biologics and Small Molecules for Atopic Dermatitis: How to Decide Which Treatment Is Right for Your Patients

The evolving discoveries in atopic dermatitis (AD) broaden our understanding of the pathogenesis of the disease and, above all, enable better management for patients. Dupilumab was the first biologic for AD, and since its approval, many new treatments have emerged in both late- and early-stage clinical trials. These trials have led to a further understanding of the pathogenesis of AD and to the identification of additional potential therapeutic targets. This review will highlight the emerging therapies and provide approaches on how to choose the right treatment for your patients.

Biologics for Treatment of Atopic Dermatitis: Current Status and Future Prospect

Atopic dermatitis (AD) is a common inflammatory skin disease characterized by intense pruritus and recurrent eczematous lesions that significantly impair quality of life. It is a heterogeneous disease affecting both children and adults. The treatment of moderate-to-severe forms of AD is challenging, as topical corticosteroids are often insufficient to achieve disease control or inappropriate and off-label use of immunosuppressants may have significant undesirable side effects. The development of targeted biologic therapies specifically for AD is thus highly desirable. Dupilumab is the only biologic therapy that is Food and Drug Administration approved for the treatment of moderate-to-severe AD in patients 6 years and older, with consistent long-term efficacy and safety trial data. In this article, we review the mechanisms, safety, and efficacy of dupilumab from recent clinical trials, and we review the current data, mechanism of action, clinical efficacy, and limitations of new biologics currently in phase 2 and 3 clinical trials (lebrikizumab, tralokinumab, nemolizumab, tezepelumab, and ISB 830).

The Role of the Environment and Exposome in Atopic Dermatitis

Purpose of review

Atopic dermatitis (AD) is a chronic inflammatory skin disorder affecting up to 20% of children and up to 5% of adults worldwide, contributing to significant disease-related morbidity in this patient cohort. Its aetiopathogenesis is underpinned by multiple factors, including genetic susceptibility, skin barrier defects, a skewed cutaneous immune response and microbiome perturbation in both the skin and the gut. In this review, we aim to examine the biological effects of key environmental exposures (the sum of which is termed the “exposome”) at the population, community and individual levels in order to describe their effect on AD pathogenesis.

Recent findings

It is now understood that as well as considering the type of environmental exposure with regard to its effect on AD pathogenesis, the dosage and timing of the exposure are both critical domains that may lead to either exacerbation or amelioration of disease. In this review, we consider the effects of population-wide exposures such as climate change, migration and urbanization; community-specific exposures such as air pollution, water hardness and allergic sensitisation; and individual factors such as diet, microbiome alteration, psychosocial stress and the impact of topical and systemic therapy.

Summary

This review summarises the interaction of the above environmental factors with the other domains of AD pathogenesis, namely, the inherent genetic defects, the skin barrier, the immune system and the cutaneous and gut microbiota. We specifically emphasise the timing and dosage of exposures and its effect on the cellular and molecular pathways implicated in AD.

Experimental Drugs with the Potential to Treat Atopic Eczema

INTRODUCTION

Eczema or atopic dermatitis (AD) is a chronically relapsing dermatosis characterized by pruritus and a significant impact on the quality of life.

METHODS

The authors undertook a structured search of peer-reviewed research articles from PubMed and Google Scholar. Recent and up-to-date studies relevant to the topic were included.

RESULTS

This report overviews current treatment and experimental drug for AD. Topical agents including topical phosphodiesterase E4 (PDE4) inhibitors such as crisaborole are efficacious in the treatment of AD with few side effects. Monoclonal antibodies such as dupilumab given subcutaneously are efficacious for more severe disease. Systemic treatment can ameliorate symptoms in severe and recalcitrant AD. New systemic treatment includes several traditional herbal formulations that have undergone clinical trials using modern research methodology to determine their efficacy and safety. AD is associated with many complicating psychosocial issues. Often suboptimal efficacy is due to unrealistic expectations and poor compliance making treatment difficult in spite of effective treatment and efforts in drug discovery. Randomized trials have shown that novel topical and subcutaneous medications are safe and efficacious. Regarding herbs, a methodology for the investigation of herbal medications is often flawed and scientific evidence is lacking. Experimental drugs include various biologics, PDE4 and JAK inhibitors in topical, oral, subcutaneous or intravenous forms are in various phases of trials.

CONCLUSION

Many novel medications demonstrate efficacy for AD. Experimental drugs include various biologics, PDE4 and JAK inhibitors are in various phases of trials.

Practical algorithm to inform clinical decision-making in the topical treatment of atopic dermatitis

Atopic dermatitis is a chronic relapsing, inflammatory skin disorder associated with skin barrier dysfunction, the prevalence of which has increased dramatically in developing countries. In this article, we propose a treatment algorithm for patients with mild-to-moderate and severe atopic dermatitis flares in daily clinical practice. An international panel of 15 dermatology and allergy experts from eight countries was formed to develop a practical algorithm for the treatment of patients with atopic dermatitis, with a particular focus on topical therapies. In cases of mild-to-moderate atopic dermatitis involving sensitive skin areas, the topical calcineurin inhibitor pimecrolimus should be applied twice daily at the first signs of atopic dermatitis. For other body locations, patients should apply a topical calcineurin inhibitor, either pimecrolimus or tacrolimus, twice daily at the first signs of atopic dermatitis, such as pruritus, or twice weekly in previously affected skin areas. Emollients should be used regularly. Patients experiencing acute atopic dermatitis flares in sensitive skin areas should apply a topical corticosteroid twice daily or alternate once-daily topical corticosteroid/topical calcineurin inhibitor until symptoms improve. Following improvement, topical corticosteroid therapy should be discontinued and patients switched to a topical calcineurin inhibitor. Maintenance therapy should include the use of pimecrolimus once daily for sensitive areas and tacrolimus for other body locations. This treatment algorithm can help guide clinical decision-making in the treatment of atopic dermatitis.

Production of IL-31 in CD45RO+CLA+H4R+ T Cells in Atopic Dermatitis

IL-31 is involved in pruritus in atopic dermatitis (AD) and the pathogenesis of AD. However, the mechanism of IL-31 production is not fully understood. We sought to investigate the association between CD45RO⁺CLA⁺H4R⁺ T cells and IL-31 production. Immunofluorescence studies were performed retrospectively on punch-biopsy specimens from five people with AD and three healthy controls. In addition, blood samples were collected prospectively from eight patients with AD and eight healthy controls for sorting CD45RO⁺CLA⁺H4R⁺ T cells. There was no overlap of patients between the biopsy group and the blood sampling group. Sorted cells were stimulated with 4-methylhistamine (4MH), and the level of IL-31 was measured by an enzyme-linked immunosorbent assay. Immunofluorescence showed co-localization of H4R and IL-31 in lesional AD skin but not in normal skin of healthy controls. The proportion of CLA⁺H4R⁺ T cells among CD3⁺CD45RO⁺ lymphocytes was 18.3 ± 6.2% in patients with AD and 11.2 ± 7.6% in healthy controls. In the AD group, production of IL-31 by CD45RO⁺CLA⁺H4R⁺ T cells increased from 32.4 ± 13.3 pg/mL to 47.5 ± 18.7 pg/mL by 4MH stimulation after 24 h (p < 0.001). However, in the control group, production of IL-31 was 20.1 ± 10.6 pg/mL without and 22.1 ± 9.3 pg/mL with 4MH stimulation (p > 0.05). According to our study, CD45RO⁺CLA⁺H4R⁺ T cells are an important source of IL-31 in AD, and may be a target for treatment of IL-31-induced pruritus.

New and Emerging Systemic Treatments for Atopic Dermatitis

Atopic dermatitis (AD) is a prevalent inflammatory skin condition that, depending on its severity, can cause enormous morbidity. Corticosteroids and systemic immunosuppression, traditionally standard of care for difficult-to-treat disease, have many undesirable side effects. The desire for targeted treatments along with an improved understanding of the pathophysiology of AD has spurred the development of novel treatments. In this article, we review promising new treatments and discuss how their targets—IL-13, IL-31, OX40 (CD134), and the Janus kinase family of proteins—participate in the pathogenesis of AD. We review the published phase II and III data for dupilumab, tralokinumab, lebrikizumab, nemolizumab, anti-OX40 antibody, baricitinib, abrocitinib, and upadacitinib. The introduction of new agents may offer new options, but it remains to be seen how narrow-acting agents, like single interleukin inhibitors, will compare in safety and efficacy to broad-acting agents such as JAK inhibitors.

Extended Safety Analysis of Baricitinib 2 mg in Adult Patients with Atopic Dermatitis: An Integrated Analysis from Eight Randomized Clinical Trials

BACKGROUND

Baricitinib, a selective Janus kinase 1/Janus kinase 2 inhibitor, is indicated in the European Union and Japan for the treatment of moderate-to-severe atopic dermatitis (AD) in adults who are candidates for systemic therapy.

OBJECTIVE

The objective of this study was to evaluate the safety of baricitinib 2 mg in the AD clinical program.

METHODS

Six double-blind, randomized, placebo-controlled studies, and two long-term extension studies were summarized in two datasets. Placebo comparison was based on six 16-week studies with baricitinib 2 mg. All-bari-2-mg-AD included patients who received baricitinib 2 mg at any time during the eight studies.

RESULTS

In total, 1598 patients received once-daily baricitinib 2 mg for 1434.2 patient-years of exposure (median 330 days/maximum 2.4 years). Treatment-emergent adverse events were higher for baricitinib 2 mg (57.9%) vs placebo (51.6%). Serious adverse events, serious infections, and opportunistic infections were low in frequency and similar between baricitinib 2 mg and placebo. There were no malignancies, gastrointestinal perforations, or major adverse cardiovascular events with baricitinib 2 mg in the placebo-controlled period. Herpes simplex (cluster) was higher for baricitinib 2 mg (3.8%) vs placebo (2.8%); rates decreased with extended 2 mg exposure. In All-bari-2-mg-AD, there were five malignancies other than non-melanoma skin cancer, two major adverse cardiovascular events, one peripheral venous thrombosis, one arterial thrombosis, and no pulmonary embolisms, deep vein thromboses, or deaths.

CONCLUSIONS

This integrated analysis in patients with moderate-to-severe AD confirms the established safety profile of baricitinib 2 mg. Longer exposure to treatment is required to evaluate risks of malignancies and major adverse cardiovascular events.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov identifiers: NCT02576938 (first posted 15 October, 2015); NCT03334396 (7 November, 2017); NCT03334422 (7 November, 2017); NCT03428100 (9 February, 2018); NCT03435081 (15 February, 2018); NCT03733301 (7 November, 2018); NCT03334435 (7 November, 2017); NCT03559270 (18 June, 2018).

HLA Class I Polymorphisms Influencing Both Peptide Binding and KIR Interactions Are Associated with Remission among Children with Atopic Dermatitis: A Longitudinal Study

Atopic dermatitis (AD) is a disease of immune dysregulation and skin barrier dysfunction with a relapsing, remitting course and has been associated with several different genetic risk variants. HLA represent a highly variable set of genes that code for cell surface protein molecules involved in the Ag-specific immune response, including the regulation or functioning of T cells, NK cells, and APCs. The purpose of this study was to evaluate associations between HLA class I polymorphisms and the progression of AD over time. We evaluated the associations of AD symptoms and HLA class I polymorphisms based on high-resolution two-field typing in a longitudinal cohort of children with AD (up to 10 y of follow-up). Seven hundred and ninety-two children were evaluated every 6 mo, resulting in 12,752 AD evaluations. Using generalized estimating equations and corrected p values, B*44:02 was found to be associated with AD remission (1.83 [1.35, 2.47]; p = 0.0015). The HLA-B residues at position 116 (d-aspartate) and 80 (T-threonine) were associated with remission (1.42 [1.13, 1.76], p = 0.003; corrected p = 0.028) and (1.45 [1.17, 1.80], p = 0.0008; corrected p = 0.0024), respectively. B80T is a killer-cell Ig-like receptor (KIR) site. Our findings reveal that two axes of immune response (T cell and NK cell) may influence disease progression. Identifying binding pocket changes in addition to other factors (e.g., allergens) that increase the risk or severity of AD can improve our understanding of the immunologic mechanisms associated with AD and may lead to personalized therapies for improving patient care.

Mast Cells in the Skin: Defenders of Integrity or Offenders in Inflammation?

Mast cells (MCs) are best-known as key effector cells of immediate-type allergic reactions that may even culminate in life-threatening anaphylactic shock syndromes. However, strategically positioned at the host–environment interfaces and equipped with a plethora of receptors, MCs also play an important role in the first-line defense against pathogens. Their main characteristic, the huge amount of preformed proinflammatory mediators embedded in secretory granules, allows for a rapid response and initiation of further immune effector cell recruitment. The same mechanism, however, may account for detrimental overshooting responses. MCs are not only detrimental in MC-driven diseases but also responsible for disease exacerbation in other inflammatory disorders. Focusing on the skin as the largest immune organ, we herein review both beneficial and detrimental functions of skin MCs, from skin barrier integrity via host defense mechanisms to MC-driven inflammatory skin disorders. Moreover, we emphasize the importance of IgE-independent pathways of MC activation and their role in sustained chronic skin inflammation and disease exacerbation.

Characteristics associated with clinical response to Comano thermal spring water balneotherapy in pediatric patients with atopic dermatitis

BACKGROUND

Several studies have investigated the efficacy of balneotherapy in atopic dermatitis (AD), including a pediatric open randomized clinical trial conducted at the Comano thermal spring water center, which showed a significant reduction in AD severity and an improvement of the quality of life. However, so far many studies on balneotherapy in pediatric AD have included relatively small populations without identifying patients' characteristics associated with their response. The aim of the present study was to identify any features associated with the clinical response to the Comano thermal spring water balneotherapy in a large cohort of pediatric AD patients.

METHODS

An observational study was conducted on 867 children aged ≤16 years (females 50.5%, mean patient's age 5.9 years, standard deviation ±3.6 years) with mild to severe AD who underwent balneotherapy at the Comano thermal spring water center (Comano, Trentino, Italy) from April to October 2014. Patients were stratified according to their disease severity, which was evaluated using five SCORing Atopic Dermatitis (SCORAD) categories before and immediately after a thermal spring water balneotherapy course. Potential characteristics associated with the patients' clinical response to Comano thermal spring water balneotherapy were investigated.

RESULTS

A statistically significant improvement in AD severity was observed after Comano thermal spring water balneotherapy (p < 0.0001). A significantly higher percentage of patients achieving improvement in AD severity was reported among children ≤4 years old (p < 0.0001) with early-onset AD (p < 0.0001), severe AD (p < 0.0001) or coexistent reported food allergies (p < 0.01). The therapy was well tolerated, and no relevant adverse effects were reported during the treatment course.

CONCLUSIONS

Comano thermal spring water balneotherapy is a safe complementary treatment for pediatric patients with AD, as it was able to reduce the disease severity, especially in children ≤4 years old, with early onset AD, severe AD or concomitant food allergies.

Molecular Mechanisms of Atopic Dermatitis Pathogenesis

Atopic dermatitis is a chronic, non-infectious inflammatory dermatosis. Acharacteristic feature is persistent itching of the skin. The chronic, relapsing course of the disease, economic burden, and the whole family’s involvement in the treatment process immensely reduce the quality of life of patients and their families. The disease emerges as a social problem by increasing indirect costs, such as visiting a doctor, absenteeism from work and school, and avoiding social interactions. Thepathophysiology of atopic dermatitis is complex and multifactorial. It includes genetic disorders, a defect in the epidermal barrier, an altered immune response, anddisruption of the skin’s microbial balance. The numerous complex changes at thegenetic level and innate and adaptive immunity provide the basis for characterizing the various phenotypes and endotypes of atopic dermatitis. Emerging therapies rely on the action of specific molecules involved in the disease’s pathogenesis. It may be the starting point for the individualization of atopic dermatitis treatment. This paper will try to present some molecular mechanisms of atopic dermatitis and their clinical implications.

Effectiveness of ustekinumab in patients with atopic dermatitis: analysis of real-world evidence

INTRODUCTION

Atopic dermatitis (AD) is a very common chronic inflammatory skin disease. Ustekinumab is a human monoclonal antibody approved for psoriasis, that targets the p40 subunit shared by interleukin (IL)-12 and IL-23, cytokines which may also play a role in AD. Administration of ustekinumab in AD has been presented in anecdotal reports with conflicting results. Our aim was to evaluate the precise value of this biologic drug on AD in real-world setting.

MATERIAL AND METHOD

We sistematically reviewed published data and analyzed aggregated results involving AD treated with ustekinumab. The main outcome was clinical improvement reported by each record. We classified this in three categories: "complete response", "partial response" and "no response". A multivariant model was used to assess association between response to ustekinumab and the following potential predictive factors: gender, age (age < or >50), duration of AD, history of asthma, previous use of biologic drugs, number of previous systemic therapies, serum levels of IgE and duration of ustekinumab therapy.

RESULTS

Data on 23 patients from eight articles were analyzed. Complete AD remission was reported in 8 patients (34.8%), while abscense of response was observed also in 8 patients (34.8%). Partial response was reported in 7 patients (30.4%). No differences were observed with respect to age, gender, history of asthma, naïve patient, duration of AD or duration of ustekinumab therapy.

CONCLUSION

We conclude from available data the IL-12/23 pathway is likely not an atractive target for AD. More no convincing data exist arguing against consideration of ustekinumab in AD patients. Other effective treatments are available and should be prioritized with good safety profile. Limitations are yet low number of studies and patients.WHAT'S ALREADY KNOWN ABOUT THIS TOPIC?Administration of ustekinumab in AD (atopic dermatitis) has been presented in anecdotical reports with conflicting resultsWHAT DOES THIS STUDY ADD?This work presents the largest cohort of AD patients treated with ustekinumab in a real-world setting.Ustekinumab resulted in similar rates of complete, partial and negative responses.Our findings demonstrate the IL-12/23 pathway is not an atractive target in AD.More novel and effective treatments for AD are available and should be prioritized.The impact of anti IL-12/IL-23p40 therapy in AD is still unclarified due to limited controlled trials.

RNA-Seq Identifies Marked Th17 Cell Activation and Altered CFTR Expression in Different Atopic Dermatitis Subtypes in Chinese Han Populations

Background

Patients with atopic dermatitis (AD) exhibit phenotypic variability in ethnicity and IgE status. In addition, some patients develop other allergic conditions, such as allergic rhinitis (AR), in subsequent life. Understanding the heterogeneity of AD would be beneficial to phenotype-specific therapies.

Methods

Twenty-eight Chinese AD patients and 8 healthy volunteers were enrolled in the study. High-throughput transcriptome sequencing was conducted on lesional and nonlesional skin samples from 10 AD patients and matched normal skin samples from 5 healthy volunteers. Identification of differentially expressed genes (DEGs), KEGG pathway analyses, and sample cluster analyses were conducted in the R software environment using the DEseq2, ClusterProfiler, and pheatmap R packages, respectively. qRT-PCR, Western blotting, and ELISA were used to detect gene expression levels among subtypes. Correlation analysis was performed to further investigate their correlation with disease severity.

Results

A total of 25,798 genes were detected per sample. Subgroup differential expression analysis and functional enrichment analysis revealed significant changes in the IL17 signaling pathway in Chinese EAD patients but not in IAD patients. DEGs enriched in cytokine-cytokine receptor interactions and gland secretion were considered to be associated with atopic march. Further investigations confirmed a marked IL17A upregulation in Chinese EAD with a positive relationship with total IgE level and AD severity. In addition, increased IL17A in AD patients with AR demonstrated a closer association with AR severity than IL4R. Moreover, AQP5 and CFTR were decreased in the lesions of AD patients with AR. The CFTR mRNA expression level was negatively associated with the skin IL17A level and AR severity.

Conclusion

Our research characterized marked Th17 activation in Chinese EAD patients, and altered expression of IL17A, IL4R, AQP5, and CFTR in AD patients with AR was associated with AR severity. It partially explained the phenotypic differences of AD subtypes and provided potential references for endotype-targeted therapy.

Biomarkers in atopic dermatitis-a review on behalf of the International Eczema Council

Atopic dermatitis (AD) is a common yet complex skin disease, posing a therapeutic challenge with increasingly recognized different phenotypes among variable patient populations. Because therapeutic response may vary on the basis of heterogeneous clinical and molecular phenotypes, a shift toward precision medicine approaches may improve AD management. Herein, we will consider biomarkers as potential instruments in the toolbox of precision medicine in AD and will review the process of biomarker development and validation, the opinion of AD experts on the use of biomarkers, types of biomarkers, encompassing biomarkers that may improve AD diagnosis, biomarkers reflecting disease severity, and those potentially predicting AD development, concomitant atopic diseases, or therapeutic response, and current practice of biomarkers in AD. We found that chemokine C-C motif ligand 17/thymus and activation-regulated chemokine, a chemoattractant of TH2 cells, has currently the greatest evidence for robust correlation with AD clinical severity, at both baseline and during therapy, by using the recommendations, assessment, development, and evaluation approach. Although the potential of biomarkers in AD is yet to be fully elucidated, due to the complexity of the disease, a comprehensive approach taking into account both clinical and reliable, AD-specific biomarker evaluations would further facilitate AD research and improve patient management.

IL-13 modulates ∆Np63 levels causing altered expression of barrier- and inflammation-related molecules in human keratinocytes: A possible explanation for chronicity of atopic dermatitis

BACKGROUND

Barrier disruption and an excessive immune response in keratinocytes are now considered to have important roles in the pathophysiology of atopic dermatitis (AD). Furthermore, disturbed keratinocyte differentiation is considered to underlie AD. ΔNp63, a p53-like transcription factor, is a major regulator of keratinocyte differentiation. However, the functional significance of ΔNp63 in AD has not been clarified.

OBJECTIVE

In this study, we aimed to investigate the influence of the type 2 inflammatory environment on ΔNp63 expression and AD-associated molecules regulated by ΔNp63 in keratinocytes.

METHODS

The immunohistochemical expression profiles of ΔNp63 and AD-related molecules were evaluated in human skin tissue. The function of ΔNp63 in the regulation of AD-related molecules and the influence of the type 2 inflammatory environment on ΔNp63 expression were investigated using human primary keratinocytes. Expression of ΔNp63 was manipulated using the RNA interfering method.

RESULTS

In healthy skin tissue, we observed an inverse expression pattern between ∆Np63 and some barrier-related proteins including filaggrin, caspase-14, claudin-1, and claudin-4. ΔNp63 regulated expression of these genes and proteins. In addition, production of IL-1β and IL-33, pro-inflammatory cytokines, was modulated by ΔNp63. Furthermore, prolonged IL-13 exposure increased the thickness of the three-dimensional culture of keratinocytes. IL-13 interfered with ΔNp63 downregulation during calcium-induced keratinocyte differentiation. IL-13 modulated some barrier-related and inflammation-related molecules, which were regulated by ΔNp63.

CONCLUSIONS

We have shown that ΔNp63 modulated AD-related barrier and inflammatory molecules. In addition, ΔNp63 expression was affected by IL-4/IL-13. IL-13-ΔNp63 axis would integrate two major factors of AD pathogenesis: dysregulated barrier and inflammation.

EAACI Biologicals Guidelines-dupilumab for children and adults with moderate-to-severe atopic dermatitis

Atopic dermatitis imposes a significant burden on patients, families and healthcare systems. Management is difficult, due to disease heterogeneity, co-morbidities, complexity in care pathways and differences between national or regional healthcare systems. Better understanding of the mechanisms has enabled a stratified approach to the management of atopic dermatitis, supporting the use of targeted treatments with biologicals. However, there are still many issues that require further clarification. These include the definition of response, strategies to enhance the responder rate, the duration of treatment and its regimen (in the clinic or home-based), its cost-effectiveness and long-term safety. The EAACI Guidelines on the use of dupilumab in atopic dermatitis follow the GRADE approach in formulating recommendations for each outcome and age group. In addition, future approaches and research priorities are discussed.

The Effectiveness of Probiotic Lactobacillus rhamnosus and Lactobacillus casei Strains in Children with Atopic Dermatitis and Cow's Milk Protein Allergy: A Multicenter, Randomized, Double Blind, Placebo Controlled Study

Probiotics seem to have promising effects in the prevention and treatment of allergic conditions including atopic dermatitis (AD) and food allergy. The purpose of this multicenter randomized placebo-controlled trial was to evaluate the effectiveness of a probiotic preparation comprising Lactobacillus rhamnosus ŁOCK 0900, Lactobacillus rhamnosus ŁOCK 0908, and Lactobacillus casei ŁOCK 0918 in children under 2 years of age with AD and a cow’s milk protein (CMP) allergy. The study enrolled 151 children, who—apart from being treated with a CMP elimination diet—were randomized to receive the probiotic preparation at a daily dose of 10⁹ bacteria or a placebo for three months, with a subsequent nine-month follow-up. The primary outcomes included changes in AD symptom severity assessed with the scoring AD (SCORAD) index and in the proportion of children with symptom improvement (a SCORAD score decreased by at least 30% in comparison with that at baseline). After the three-month intervention, both the probiotic and placebo groups showed a significant (p < 0.0001) decrease in SCORAD scores, which was maintained nine months later. The percentage of children who showed improvement was significantly higher in the probiotic than in the placebo group (odds ratio (OR) 2.56; 95% confidence interval (CI) 1.13–5.8; p = 0.012) after three months. Probiotics induced SCORAD improvement mainly in allergen sensitized patients (OR 6.03; 95% CI 1.85–19.67, p = 0.001), but this positive effect was not observed after nine months. The results showed that the mixture of probiotic ŁOCK strains offers benefits for children with AD and CMP allergy. Further research is necessary to assess the effect of probiotic supplementation on the development of immune tolerance (NCT04738565).

Nomenclature and clinical phenotypes of atopic dermatitis

Atopic dermatitis is a heterogeneous disease and resists classification. In this review, we discuss atopic dermatitis nomenclature and identify morphologic phenotypes, which will facilitate correct diagnoses and development of treatment strategies. We support using the term 'atopic dermatitis' rather than eczema, because it describes the allergic background and inflammation ('itis') as drivers of the disease. Atopic dermatitis has many morphologic manifestations that vary by topographic area affected, age, or race and require consideration in differential diagnosis. Different phenotypes based on morphology and topographic location, ethnicity, and age are discussed. A better-defined phenotype identification for atopic dermatitis will facilitate earlier and correct diagnosis of this complex condition and inform selection of the most appropriate treatment choice in an era in which targeted therapies may generate more individualized patient care.

Immunoinflammatory Biomarkers in Serum Are Associated with Disease Severity in Atopic Dermatitis

BACKGROUND

A growing body of evidence links various biomarkers to atopic dermatitis (AD). Still, little is known about the association of specific biomarkers to disease characteristics and severity in AD.

OBJECTIVE

To explore the relationship between various immunological markers in the serum and disease severity in a hospital cohort of AD patients.

METHODS

Outpatients with AD referred to the Department of Dermatology, Bispebjerg Hospital, Copenhagen, Denmark, were divided into groups based on disease severity (SCORAD). Serum levels of a preselected panel of immunoinflammatory biomarkers were tested for association with disease characteristics. Two machine learning models were developed to predict SCORAD from the measured biomarkers.

RESULTS

A total of 160 patients with AD were included; 53 (33.1%) with mild, 73 (45.6%) with moderate, and 34 (21.3%) with severe disease. Mean age was 29.2 years (range 6-70 years) and 84 (52.5%) were females. Numerous biomarkers showed a statistically significant correlation with SCORAD, with the strongest correlations seen for CCL17/thymus and activation-regulated chemokine (chemokine ligand-17/TARC) and CCL27/cutaneous T cell-attracting-chemokine (CTACK; Spearman R of 0.50 and 0.43, respectively, p < 0.001). Extrinsic AD patients were more likely to have higher mean SCORAD (p < 0.001), CCL17 (p < 0.001), CCL26/eotaxin-3 (p < 0.001), and eosinophil count (p < 0.001) than intrinsic AD patients. Predictive models for SCORAD identified CCL17, CCL27, serum total IgE, IL-33, and IL-5 as the most important predictors for SCORAD, but with weaker associations than single cytokines.

CONCLUSIONS

Specific immunoinflammatory biomarkers in the serum, mainly of the Th2 pathway, are correlated with disease severity in patients with AD. Predictive models identified biomarkers associated with disease severity but this finding warrants further investigation.

Tape strips in dermatology research

Tape strips have been used widely in dermatology research as a minimally invasive method to sample the epidermis, avoiding the need for skin biopsies. Most research has focused on epidermal pathology, such as atopic eczema, but there is increasing research into the use of tape strips in other dermatoses, such as skin cancer, and the microbiome. This review summarizes the technique of tape stripping, and discusses which dermatoses have been studied by tape stripping and alternative minimally invasive sampling methods. We review the number of tape strips needed from each patient and the components of the epidermis that can be obtained by tape stripping. With a focus on protein and RNA extraction, we address the techniques used to process tape strips. There is no optimal protocol to extract protein, as this depends on the abundance of the protein studied, its level of expression in the epidermis and its solubility. Many variables can alter the amount of protein obtained from tape strips, which must be standardized to ensure consistency between samples. No study has compared different RNA extraction techniques, but our own experience is that RNA yield is optimized by using 20 tape strips and the use of a cell scraper.