Genetic and epigenetic studies of atopic dermatitis

Consensus Recommendations for the Management of Atopic Dermatitis in the United Arab Emirates

Atopic dermatitis often begins in infancy and follows a chronic course of exacerbations and remissions. The etiology is complex and involves numerous factors that contribute to skin barrier defect and inflammation. In the Middle East, the burden of atopic dermatitis is understudied. Epidemiological data specific to the Gulf region are scarce but reveal a prevalence of up to about 40% in the United Arab Emirates. Region-specific factors, such as the climate and the frequency of consanguineous marriages, may affect atopic dermatitis incidence, prevalence, and evolution over time. A panel of experts predominantly from the United Arab Emirates analyzed the evidence from published guidelines, and considered expert guidance and local treatment practices to develop clear recommendations for the management of atopic dermatitis in the United Arab Emirates. They encourage a systematic approach for the diagnosis and treatment, using disease severity scores and quality-of-life measurement tools. Treatment recommendations take into consideration both established therapies and the approved systemic biologics dupilumab and tralokinumab, and the Janus kinase inhibitors baricitinib, upadacitinib, and abrocitinib.

Atopic Dermatitis and Autism Spectrum Disorders: Common Role of Environmental and Clinical Co-Factors in the Onset and Severity of Their Clinical Course

Increasing evidence suggests an association between atopic dermatitis, the most chronic inflammatory disease of the skin, and autism spectrum disorders, which are a group of neurodevelopmental diseases. Inflammation and immune dysregulation associated with genetic and environmental factors seem to characterize the pathophysiological mechanisms of both conditions. We conducted a literature review of the PubMed database aimed at identifying the clinical features and alleged risk factors that could be used in clinical practice to predict the onset of ASD and/or AD or worsen their prognosis in the context of comorbidities.

Association between single nucleotide polymorphisms of interleukin-35 genes and atopic dermatitis

Introduction

The pathogenesis of atopic dermatitis (AD) involves complex interactions between environmental factors, the skin microbiome, epidermal barrier defects, and altered immune responses that develop on a not fully understood specific genetic background.

Aim

We aimed to evaluate the contribution of single nucleotide polymorphisms (SNPs) in the IL-35 genes (IL-12A and EBI3) towards AD susceptibility and clinical characteristics of AD in the Polish population. Two SNPs (rs568408, rs582054) in IL-12A and one SNP (rs428253) in EBI3 were selected.

Material and methods

Blood samples were collected from 202 AD patients and 178 healthy individuals. SNPs in IL-35 genes were analysed by the polymerase chain reaction with sequence-specific primers (SSP-PCR) method.

Results

For IL-12A rs568408, the AA genotype was significantly linked to increased odds of AD (OR = 34.61; 95% CI: 2.06-579.97, p = 0.0137) and marginally associated with normal total serum IgE levels (OR = 2.82; 95% CI: 0.97-8.16; p = 0.05), while the GA genotype showed significantly reduced odds of AD (OR = 0.53; 95% CI: 0.34-0.81; p = 0.0035). In the context of IL-12A rs582054, TT genotype carriers had increased odds of AD (OR = 2.05; 95% CI: 1.08-3.85; p = 0.03). Patients with the GG genotype of EBI3 rs428253 had decreased odds of high total serum IgE levels (OR = 0.42; 95% CI: 0.20-0.86; p = 0.02) and milder pruritus severity compared to CC genotype carriers (4.12 vs. 7.50; p = 0.02).

Conclusions

IL-35 genetic variations appear to play a role in AD pathogenesis.

TH2-driven manifestations of inborn errors of immunity

Monogenic lesions in pathways critical for effector functions responsible for immune surveillance, protection against autoinflammation, and appropriate responses to allergens and microorganisms underlie the pathophysiology of inborn errors of immunity (IEI). Variants in cytokine production, cytokine signaling, epithelial barrier function, antigen presentation, receptor signaling, and cellular processes and metabolism can drive autoimmunity, immunodeficiency, and/or allergic inflammation. Identification of these variants has improved our understanding of the role that many of these proteins play in skewing toward TH2-related allergic inflammation. Early-onset or atypical atopic disease, often in conjunction with immunodeficiency and/or autoimmunity, should raise suspicion for an IEI. This becomes a diagnostic dilemma if the initial clinical presentation is solely allergic inflammation, especially when the prevalence of allergic diseases is becoming more common. Genetic sequencing is necessary for IEI diagnosis and is helpful for early recognition and implementation of targeted treatment, if available. Although genetic evaluation is not feasible for all patients with atopy, identifying atopic patients with molecular immune abnormalities may be helpful for diagnostic, therapeutic, and prognostic purposes. In this review, we focus on IEI associated with TH2-driven allergic manifestations and classify them on the basis of the affected molecular pathways and predominant clinical manifestations.

The association between atopic dermatitis and inflammatory bowel disease in adults: A cross-sectional study in a specialized atopic dermatitis clinic

BACKGROUND

Atopic dermatitis (AD) and inflammatory bowel disease (IBD) share genetic susceptibility loci with immune regulation functions. Atopic dermatitis was associated with IBD mostly in database studies.

OBJECTIVE

To assess whether AD is associated with an increased prevalence of IBD in a tertiary dermatology clinic.

METHODS

A retrospective cross-sectional analysis using medical records of adults with verified AD followed up at an AD clinic, compared with age- and sex-matched (1:2) controls from the general dermatology clinic in the same hospital.

RESULTS

Overall, 9/364 (2.47%) of patients with AD had verified IBD, compared with 7/725 (0.97%) of controls (p = 0.0512). In multivariable logistic regression adjusting for age, gender and smoking, the association became significant (adjusted OR = 3.89, 95% CI: 1.28-11.85). Stratified for AD severity, only moderate-to-severe AD was associated with IBD (p = 0.035), with an adjusted OR of 4.45 (95% CI: 1.43-13.90). Mild AD was not associated with IBD, but the study was not powered for this sub-analysis. In the AD group, older age was associated with IBD (p = 0.0172).

CONCLUSION

This study, in a robustly verified cohort of patients, supports an association between AD, especially the moderate-to-severe forms, and IBD. A multidisciplinary approach for patients with moderate-to-severe AD should extend to consider IBD.

Evaluation of Childhood Allergy Risk Among Pregnant Women in a Tertiary Care Hospital in Thailand

OBJECTIVES

This study aims to evaluate the prevalence of pregnant women whose children are at higher risk for childhood allergies and to assess knowledge of risk assessment and prevention strategies.

METHODS

A cross-sectional study was conducted on 310 pregnant women in an antenatal care clinic at a tertiary care hospital in Thailand. In addition to baseline demographic and obstetric characteristics, all participating pregnant women were asked to complete a questionnaire regarding risk evaluation and knowledge of childhood allergies on various topics. A childhood allergy risk assessment was evaluated based on the history of allergy disease in immediate family members. The questionnaire on knowledge was derived from a guideline issued by the Allergy, Asthma, and Immunology Association of Thailand, with possible scores of 0-30.

RESULTS

The mean maternal age was 30.6 years, and 139 (44.8%) were nulliparous. Overall, 86 couples (27.7%) were at high risk for childhood allergies. The mean total knowledge score was 15.2 out of 30, and only 24 women (7.7%) had an overall score of >20, and 40 women (12.9%) had an overall score of ≤10. The mean knowledge score for almost every subtopic was less than half of the possible points, except for the risk reduction strategies during pregnancy. Comparisons between those with higher and lower scores (≥16 vs. ≤15 points) showed that women with higher knowledge scores were significantly more likely to have had a previous child with an allergy (p=0.010).

CONCLUSION

The prevalence of pregnant women whose children were at higher risk for childhood allergies was 27.7% (86 of 310 couples). The women had limited knowledge of childhood allergies with regard to risk assessment, risk reduction strategies, and various interventions. The only factor associated with a higher knowledge score was having a previous child with an allergy.

Effect of Chloroquine on Type 2 Inflammatory Response in MC903-Induced Atopic Dermatitis Mice

Introduction

Atopic dermatitis (AD) is a chronic, non-infectious inflammatory dermatosis. Chloroquine (CQ) has long been proven to possess anti-inflammatory properties.

Objective

This paper aims to investigate the impact of CQ on type 2 inflammatory response in MC903-induced AD mice.

Methods

An AD mouse model was established via MC903 induction. After CQ treatment, AD mice were intraperitoneally injected with polyinosinic: polycyclic acid [poly (I:C)] or Nigericin. Dermatitis severity was scored, and the thickness of the left ear was measured. The pathological changes in mouse skin tissues were observed by H&E staining. The number of mast cells was counted via TB staining. The content of peripheral blood T-helper 2 (Th2) cells and levels of immunoglobulin E (IgE), thymic stromal-derived lymphopoietin (TSLP), interleukin (IL)-4, IL-13, interferon (IFN)-γ, IL-1β, and IL-18 were assessed by flow cytometry and ELISA. The levels of toll-like receptor 3 (TLR3), NLRP3, ASC, and cleaved caspase-1 proteins in skin tissues were determined by Western blot.

Results

CQ treatment abated dermatitis severity and left ear thickness in AD mice, alleviated skin damage, reduced mast cell number, diminished IgE, TSLP, IL-4, and IL-13 levels, and peripheral blood Th2 cell content, with no significant changes in IFN-γ level. CQ alleviated type 2 inflammatory response in AD mice by inhibiting the activation of TLR3. CQ suppressed NLRP3 inflammasome activation. Activating TLR3/NLRP3 annulled CQ-mediated alleviation on type 2 inflammatory response in AD mice.

Conclusion

CQ alleviated type 2 inflammatory response in AD mice by inhibiting TLR3 activation and NLRP3 inflammasome activation.

Natural Sources of Therapeutic Agents Used in Skin Conditions

Skin conditions are numerous and often have a major impact on patients' quality of life, and effective and safe treatment is very important. The conventional drugs used for skin diseases are usually corticosteroids and antimicrobial products that can induce various side effects, especially with long-term use, which is why researchers are studying alternatives, especially biologically active natural products. Three products caught our attention: bee venom (BV), due to reported experimental results showing anti-inflammatory, antibacterial, antiviral, antioxidant, antimycotic, and anticancer effects, Ficus carica (FC) due to its demonstrated antioxidant, antibacterial, and anti-inflammatory action, and finally Geranium essential oil (GEO), with proven antifungal, antibacterial, anti-inflammatory, and antioxidant effects. Following a review of the literature, we produced this paper, which presents a review of the potential therapeutic applications of the three products in combating various skin conditions and for skin care, because BV, FC, and GEO have common pharmacological actions (anti-inflammatory, antibacterial, and antioxidant). We also focused on studying the safety of the topical use of BV, FC, and GEO, and new approaches to this. This paper presents the use of these natural therapeutic agents to treat patients with conditions such as vitiligo, melasma, and melanoma, as well as their use in treating dermatological conditions in patients with diabetes.

Epigenetic control of inflammation in Atopic Dermatitis

Atopic dermatitis (AD), also known as atopic eczema, is a common but also complex chronic, itchy skin condition with underlying inflammation of the skin. This skin ailment is prevalent worldwide and affects people of all ages, particularly children below five years of age. The itching and resulting rashes in AD patients are often the result of inflammatory signals, thus necessitating a closer look at the inflammation-regulating mechanisms for putative relief, care and therapy. Several chemical- as well as genetically-induced animal models have established the importance of targeting pro-inflammatory AD microenvironment. Epigenetic mechanisms are gaining attention towards a better understanding of the onset as well as the progression of inflammation. Several physiological processes with implications in pathophysiology of AD, such as, barrier dysfunction either due to reduced filaggrin / human β-defensins or altered microbiome, reprograming of Fc receptors with resulting overexpression of high affinity IgE receptors, elevated eosinophil numbers or the elevated IL-22 production by CD4 + T cells have underlying epigenetic mechanisms that include differential promoter methylation and/or regulation by non-coding RNAs. Reversing these epigenetic changes has been verified to reduce inflammatory burden through altered secretion of cytokines IL-6, IL-4, IL-13, IL-17, IL-22 etc, with benefit against AD progression in experimental models. A thorough understanding of epigenetic remodeling of inflammation in AD has the potential of opening avenues for novel diagnostic, prognostic and therapeutic options.

Multi-Omics Approach to Improved Diagnosis and Treatment of Atopic Dermatitis and Psoriasis

Psoriasis and atopic dermatitis fall within the category of cutaneous immune-mediated inflammatory diseases (IMIDs). The prevalence of IMIDs is increasing in industrialized societies, influenced by both environmental changes and a genetic predisposition. However, the exact immune factors driving these chronic, progressive diseases are not fully understood. By using multi-omics techniques in cutaneous IMIDs, it is expected to advance the understanding of skin biology, uncover the underlying mechanisms of skin conditions, and potentially devise precise and personalized approaches to diagnosis and treatment. We provide a narrative review of the current knowledge in genomics, epigenomics, and proteomics of atopic dermatitis and psoriasis. A literature search was performed for articles published until 30 November 2023. Although there is still much to uncover, recent evidence has already provided valuable insights, such as proteomic profiles that permit differentiating psoriasis from mycosis fungoides and β-defensin 2 correlation to PASI and its drop due to secukinumab first injection, among others.

TNS1 and NRXN1 Genes Interacting With Early-Life Smoking Exposure in Asthma-Plus-Eczema Susceptibility

PURPOSE

Numerous genes have been associated with allergic diseases (asthma, allergic rhinitis, and eczema), but they explain only part of their heritability. This is partly because most previous studies ignored complex mechanisms such as gene-environment (G-E) interactions and complex phenotypes such as co-morbidity. However, it was recently evidenced that the co-morbidity of asthma-plus-eczema appears as a sub-entity depending on specific genetic factors. Besides, evidence also suggest that gene-by-early life environmental tobacco smoke (ETS) exposure interactions play a role in asthma, but were never investigated for asthma-plus-eczema. To identify genetic variants interacting with ETS exposure that influence asthma-plus-eczema susceptibility.

METHODS

To conduct a genome-wide interaction study (GWIS) of asthma-plus-eczema according to ETS exposure, we applied a 2-stage strategy with a first selection of single nucleotide polymorphisms (SNPs) from genome-wide association meta-analysis to be tested at a second stage by interaction meta-analysis. All meta-analyses were conducted across 4 studies including a total of 5,516 European-ancestry individuals, of whom 1,164 had both asthma and eczema.

RESULTS

Two SNPs showed significant interactions with ETS exposure. They were located in 2 genes, NRXN1 (2p16) and TNS1 (2q35), never reported associated and/or interacting with ETS exposure for asthma, eczema or more generally for allergic diseases. TNS1 is a promising candidate gene because of its link to lung and skin diseases with possible interactive effect with tobacco smoke exposure.

CONCLUSIONS

This first GWIS of asthma-plus-eczema with ETS exposure underlines the importance of studying sub-phenotypes such as co-morbidities as well as G-E interactions to detect new susceptibility genes.

Identification of FCER1G as a cyclosporin A plus corticosteroid sensitization gene in female patients with Vogt-Koyanagi-Harada disease

The resistance development of the combination regimen of corticosteroids (CS) with cyclosporin A (CsA) leads to therapeutic failure of some patients with autoimmune diseases. In the male patients with Vogt-Koyanagi-Harada (VKH) disease, we have identified RPS4Y1 as an important resistance gene of the regimen and a functional mediator of chlorambucil (CLB). However, it remains unclear what is responsible for the resistance in female patients. In the present study, we performed RNA sequencing, tandem mass tag (TMT) proteomics, gain- and loss-of-function assays and rescue assays to screen and validate potential resistant mediators. The results showed that only Fc epsilon receptor Ig (FCER1G) exhibited significantly differential expression in CD4+ T cells among female CsA & CS resistant, sensitive and CLB & CsA & CS treated patients at transcription and protein levels. Inhibition of FCER1G was demonstrated to modulate CD4+ T cell resistance to CsA & CS in female patients. Importantly, the inhibition was mediated by elevated DNA methylation in the promoter region of the FCER1G gene. Moreover, we found that the salvage effect of CLB on CsA & CS resistance was mediated by an increased FCER1G expression via DNA demethylation in female patients. Taken together, the downregulation of FCER1G due to DNA hypermethylation is responsible for the resistance to CsA & CS and CLB reverses this resistance by inducing FCER1G expression via DNA demethylation in female patients. Modulation of FCER1G would be a promising sensitization strategy in female patients with resistance to CsA & CS.

Atopic Dermatitis: Molecular Alterations between Lesional and Non-Lesional Skin Determined Noninvasively by In Vivo Confocal Raman Microspectroscopy

Atopic dermatitis (AD)/atopic eczema is a chronic relapsing inflammatory skin disease affecting nearly 14% of the adult population. An important pathogenetic pillar in AD is the disrupted skin barrier function (SBF). The atopic stratum corneum (SC) has been examined using several methods, including Raman microspectroscopy, yet so far, there is no depth-dependent analysis over the entire SC thickness. Therefore, we recruited 21 AD patients (9 female, 12 male) and compared the lesional (LAS) with non-lesional atopic skin (nLAS) in vivo with confocal Raman microspectroscopy. Our results demonstrated decreased total intercellular lipid and carotenoid concentrations, as well as a shift towards decreased orthorhombic lateral lipid organisation in LAS. Further, we observed a lower concentration of natural moisturising factor (NMF) and a trend towards increased strongly bound and decreased weakly bound water in LAS. Finally, LAS showed an altered secondary and tertiary keratin structure, demonstrating a more folded keratin state than nLAS. The obtained results are discussed in comparison with healthy skin and yield detailed insights into the atopic SC structure. LAS clearly shows molecular alterations at certain SC depths compared with nLAS which imply a reduced SBF. A thorough understanding of these alterations provides useful information on the aetiology of AD and for the development/control of targeted topical therapies.

JAK1 inhibitors for the treatment of atopic dermatitis: a focus on pharmacokinetic considerations

INTRODUCTION

Atopic dermatitis (AD) is associated with reduced quality of life, depression, and anxiety, making efficacious and safe treatments a priority. We will focus on the safety, efficacy, and pharmacokinetics of JAK1 inhibitors used in the treatment of AD.

AREAS COVERED

In this review, the pharmacodynamics, pharmacokinetics, safety, and efficacy of JAK1 inhibitors for the treatment of atopic dermatitis are discussed. The data was obtained by searching ClinicalTrials.gov, PubMed, and Google Scholar. Articles between January 2012 and March 2023 were considered for inclusion.

EXPERT OPINION

Given the rare, but serious black box warnings with JAK inhibitors, patients and providers may be weary of initiating treatment. In these instances, clinicians may weigh the risks and benefits of treatment with this class. Risk is relative, and while there are risks to treating AD with JAK inhibitors, there are also risks to untreated or undertreated AD, including infection and impairments in mental, physical, and psychosocial function. While JAK1 inhibitors appear to be safe, they were only recently approved for AD in January 2022, and more long-term safety data is needed. We expect to see additional FDA approval of these drugs, new formulations, and more safety and efficacy data in the future.

Genomic, Epigenomic, Transcriptomic, Proteomic and Metabolomic Approaches in Atopic Dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease with a high prevalence in the developed countries. It is associated with atopic and non-atopic diseases, and its close correlation with atopic comorbidities has been genetically demonstrated. One of the main roles of genetic studies is to comprehend the defects of the cutaneous barrier due to filaggrin deficit and epidermal spongiosis. Recently, epigenetic studies started to analyze the influence of the environmental factors on gene expression. The epigenome is considered to be a superior second code that controls the genome, which includes alterations of the chromatin. The epigenetic changes do not alter the genetic code, however, changes in the chromatin structure could activate or inhibit the transcription process of certain genes and consequently, the translation process of the new mRNA into a polypeptide chain. In-depth analysis of the transcriptomic, metabolomic and proteomic studies allow to unravel detailed mechanisms that cause AD. The extracellular space and lipid metabolism are associated with AD that is independent of the filaggrin expression. On the other hand, around 45 proteins are considered as the principal components in the atopic skin. Moreover, genetic studies based on the disrupted cutaneous barrier can lead to the development of new treatments targeting the cutaneous barrier or cutaneous inflammation. Unfortunately, at present, there are no target therapies that focus on the epigenetic process of AD. However, in the future, miR-143 could be an important objective for new therapies, as it targets the miR-335:SOX axis, thereby restoring the miR-335 expression, and repairing the cutaneous barrier defects.

Binding, Neutralization and Internalization of the Interleukin-13 Antibody, Lebrikizumab

INTRODUCTION

IL-13 is the primary upregulated cytokine in atopic dermatitis (AD) skin and is the pathogenic mediator driving AD pathophysiology. Lebrikizumab, tralokinumab and cendakimab are therapeutic monoclonal antibodies (mAb) that target IL-13.

METHODS

We undertook studies to compare in vitro binding affinities and cell-based functional activities of lebrikizumab, tralokinumab and cendakimab.

RESULTS

Lebrikizumab bound IL-13 with higher affinity (as determined using surface plasma resonance) and slower off-rate. It was more potent in neutralizing IL-13-induced effects in STAT6 reporter and primary dermal fibroblast periostin secretion assays than either tralokinumab or cendakimab. Live imaging confocal microscopy was employed to determine the mAb effects on IL-13 internalization into cells via the decoy receptor IL-13Rα2, using A375 and HaCaT cells. The results showed that only the IL-13/lebrikizumab complex was internalized and co-localized with lysosomes, whereas IL-13/tralokinumab or IL-13/cendakimab complexes did not internalize.

CONCLUSION

Lebrikizumab is a potent, neutralizing high-affinity antibody with a slow disassociation rate from IL-13. Additionally, lebrikizumab does not interfere with IL-13 clearance. Lebrikizumab has a different mode of action to both tralokinumab and cendakimab, possibly contributing to the clinical efficacy observed by lebrikizumab in Ph2b/3 AD studies.

Association of IL-4 and IL-18 genetic polymorphisms with atopic dermatitis in Chinese children

Background

Atopic dermatitis (AD) is a common chronic inflammatory skin disease, adversely affecting nearly 20% of the pediatric population worldwide. Interleukin-4 (IL-4) and interleukin-18 (IL-18) are considered to be involved in the pathogenesis and development of AD. The aim of this study was to investigate the association of IL-4 and IL-18 gene polymorphisms with the susceptibility and severity of AD in Chinese children.

Methods

Six candidate single nucleotide polymorphisms (SNPs) in IL-4 and IL-18 genes were genotyped through multi-PCR combined with next-generation sequencing in 132 AD children and 100 healthy controls, and all the analyses were performed on blood genome DNA.

Results

The frequencies of G allele, CG genotype and CG + GG genotype of IL-4 rs2243283, as well as the haplotype IL-4/GTT (rs2243283-rs2243250-rs2243248) were all significantly decreased in AD patients compared with the controls [G vs. C: P = 0.033, OR = 0.59; CG vs. CC: P = 0.024, OR = 0.47; CG + GG vs. CC: P = 0.012, OR = 0.49; GTT vs. CCT: P = 0.011, OR = 0.65]. Moreover, the frequencies of A allele, AA genotype and AG + AA genotype of IL-18 rs7106524, along with the haplotype IL-18/CAA (rs187238-rs360718-rs7106524) were statistically increased in the severe AD patients (A vs. G: P < 0.001, OR = 2.79; AA vs. GG: P = 0.003, OR = 5.51; AG + AA vs. GG: P = 0.036, OR = 2.93; CAA vs. CAG: P = 0.001, OR = 2.86).

Conclusions

Our findings suggested that genetic variation in IL-4 rs2243283 such as G allele, CG genotype and CG + GG genotype might confer the reduced susceptibility to AD in Chinese children. Furthermore, A allele, AA genotype and AG + AA genotype of IL-18 rs7106524 explored the strong association with severity in Chinese AD children.

Chitosan-based drug delivery systems for skin atopic dermatitis: recent advancements and patent trends

Atopic dermatitis (AD) is a complex, relapsing inflammatory skin disease with a considerable social and economic burden globally. AD is primarily characterized by its chronic pattern and it can have important modifications in the quality of life of the patients and caretakers. One of the fastest-growing topics in translational medicine today is the exploration of new or repurposed functional biomaterials into drug delivery therapeutic applications. This area has gained a considerable amount of research which produced many innovative drug delivery systems for inflammatory skin diseases like AD. Chitosan, a polysaccharide, has attracted attention as a functional biopolymer for diverse applications, especially in pharmaceutics and medicine, and has been considered a promising candidate for AD treatment due to its antimicrobial, antioxidative, and inflammatory response modulation properties. The current pharmacological treatment for AD involves prescribing topical corticosteroid and calcineurin inhibitors. However, the adverse reactions associated with the long-term usage of these drugs such as itching, burning, or stinging sensation are also well documented. Innovative formulation strategies, including the use of micro- and nanoparticulate systems, biopolymer hydrogel composites, nanofibers, and textile fabrication are being extensively researched with an aim to produce a safe and effective delivery system for AD treatment with minimal side effects. This review outlines the recent development of various chitosan-based drug delivery systems for the treatment of AD published in the past 10 years (2012-2022). These chitosan-based delivery systems include hydrogels, films, micro-, and nanoparticulate systems as well as chitosan textile. The global patent trends on chitosan-based formulations for the AD are also discussed.

The IL-4Rα Q576R polymorphism is associated with increased severity of atopic dermatitis and exaggerates allergic skin inflammation in mice

BACKGROUND

Atopic dermatitis (AD) is characterized by TH2-dominated skin inflammation and systemic response to cutaneously encountered antigens. The TH2 cytokines IL-4 and IL-13 play a critical role in the pathogenesis of AD. The Q576->R576 polymorphism in the IL-4 receptor alpha (IL-4Rα) chain common to IL-4 and IL-13 receptors alters IL-4 signaling and is associated with asthma severity.

OBJECTIVE

We sought to investigate whether the IL-4Rα R576 polymorphism is associated with AD severity and exaggerates allergic skin inflammation in mice.

METHODS

Nighttime itching interfering with sleep, Rajka-Langeland, and Eczema Area and Severity Index scores were used to assess AD severity. Allergic skin inflammation following epicutaneous sensitization of mice 1 or 2 IL-4Rα R576 alleles (QR and RR) and IL-4Rα Q576 (QQ) controls was assessed by flow cytometric analysis of cells and quantitative RT-PCR analysis of cytokines in skin.

RESULTS

The frequency of nighttime itching in 190 asthmatic inner-city children with AD, as well as Rajka-Langeland and Eczema Area and Severity Index scores in 1116 White patients with AD enrolled in the Atopic Dermatitis Research Network, was higher in subjects with the IL-4Rα R576 polymorphism compared with those without, with statistical significance for the Rajka-Langeland score. Following epicutaneous sensitization of mice with ovalbumin or house dust mite, skin infiltration by CD4+ cells and eosinophils, cutaneous expression of Il4 and Il13, transepidermal water loss, antigen-specific IgE antibody levels, and IL-13 secretion by antigen-stimulated splenocytes were significantly higher in RR and QR mice compared with QQ controls. Bone marrow radiation chimeras demonstrated that both hematopoietic cells and stromal cells contribute to the mutants' exaggerated allergic skin inflammation.

CONCLUSIONS

The IL-4Rα R576 polymorphism predisposes to more severe AD and increases allergic skin inflammation in mice.

Pterostilbene reduces the progression of atopic dermatitis via modulating inflammatory and oxidative stress biomarkers in mice

Atopic dermatitis (AD) is one of the most prevalent chronic skin inflammatory disorders requiring continuous treatment and care. Pterostilbene (PTN) belongs to stilbene and is a polyphenolic compound of natural origin. It is similar to resveratrol and has analogous anti-inflammatory, anti-oxidant, and anti-carcinogenic characteristics. This study was intended to evaluate the effect of PTN against atopic dermatitis. The disease was induced by sensitization with 2,4-dinitrochlorobenzene (DNCB) in mice. The standard control group (SCG) received topical 0.1% tacrolimus (TC), whereas three other treatment groups received daily topical PTN at 0.2, 0.6, and 1% w/w for 28 days. Dermatitis scoring, ear thickness, and body weight of animals were weekly determined while other parameters were assessed at the termination of the experiment. PTN reduced the ear weight, skin thickness, and the weight and size of thymus glands and spleen in comparison with diseased animals. PTN also reduced the elevated immunoglobulin E (IgE) level and blood inflammatory cells in diseased mice. The histopathological findings showed a decreased epidermal thickness in PTN-treated groups. Moreover, treatment with PTN improved the amount of oxidative stress markers in the skin of the diseased mice. The expressions of IL-4, IL-6, TNF-α, and NF-κB in the skin of diseased mice were also reduced by PTN. This study concludes that PTN ameliorated the symptoms of atopic dermatitis through the reduction of inflammation, oxidative damage, and inflammatory cytokines in the skin of diseased animals. Therefore, PTN must be further investigated for the treatment of AD complications and other inflammatory skin disorders.

Immunohistochemical Analysis of Adhesion Molecules E-Selectin, Intercellular Adhesion Molecule-1, and Vascular Cell Adhesion Molecule-1 in Inflammatory Lesions of Atopic Dermatitis

E-selectin, ICAM-1 (intercellular adhesion molecule-1), and VCAM-1 (vascular cell adhesion molecule-1) play a role in atopic dermatitis (AD). This study aimed to evaluate their expression in skin biopsy specimens of patients diagnosed with AD using an optimized computer program. A descriptive analysis and comparison of digitally measured surface area and cell number were performed. The number of E-selectin-positive cells did not vary between the groups. In patients with AD, decreases of 1.2-fold for ICAM-1- and 1.3-fold for VCAM-1- positive cells were observed. The E-selectin-positive epidermal surface area increased (p < 0.001), while ICAM1 and VCAM1 decreased 2.5-fold and 2-fold, respectively, compared to controls. In the AD-affected skin, the E-selectin-positive endothelial area was 3.5-fold larger (p < 0.001), and the ICAM1-positive area was almost 4-fold larger (p < 0.001). E-selectin and ICAM-1 were expressed in the control dermis moderately and weakly, respectively. A strong E-selectin signal was detected in the AD-affected skin macrophages and a strong ICAM-1 signal in the dermal vessel endothelium. In the endothelial cells of AD-affected skin, no VCAM-1 signal could be found. E-selectin, ICAM-1, and VCAM-1 expression show significant disease-specific changes between AD-affected and control skin. The combination of digital analysis and a pathologist’s evaluation may present a valuable follow-up of AD activity parameters.

Gram-positive anaerobic cocci guard skin homeostasis by regulating host-defense mechanisms

In atopic dermatitis (AD), chronic skin inflammation is associated with skin barrier defects and skin microbiome dysbiosis including a lower abundance of Gram-positive anaerobic cocci (GPACs). We here report that, through secreted soluble factors, GPAC rapidly and directly induced epidermal host-defense molecules in cultured human keratinocytes and indirectly via immune-cell activation and cytokines derived thereof. Host-derived antimicrobial peptides known to limit the growth of Staphylococcus aureus-a skin pathogen involved in AD pathology-were strongly upregulated by GPAC-induced signaling through aryl hydrocarbon receptor (AHR)-independent mechanisms, with a concomitant AHR-dependent induction of epidermal differentiation genes and control of pro-inflammatory gene expression in organotypic human epidermis. By these modes of operandi, GPAC may act as an "alarm signal" and protect the skin from pathogenic colonization and infection in the event of skin barrier disruption. Fostering growth or survival of GPAC may be starting point for microbiome-targeted therapeutics in AD.

How an Immune-Factor-Based Formulation of Micro-Immunotherapy Could Interfere with the Physiological Processes Involved in the Atopic March

Allergic diseases consist of improper inflammatory reactions to antigens and are currently an important healthcare concern, especially considering their increasing worldwide development in recent decades. The "atopic march" defines the paradigm of allergic diseases occurring in chronological order and displaying specific spatial manifestations, as they usually start as atopic dermatitis (AD) and food allergies during infancy and progressively evolve into allergic asthma (AA) and allergic rhinitis (AR) or rhino-conjunctivitis in childhood. Many immune cell subtypes and inflammatory factors are involved in these hypersensitivity reactions. In particular, the T helpers 2 (Th2) subset, through its cytokine signatures made of interleukins (ILs), such as IL-4, IL-5, IL-10, and IL-13, as well as mast cells and their related histamine pathways, contribute greatly to the perpetuation and evolution of the atopic march. By providing low doses (LD) and ultra-low doses (ULD) of ILs and immune factors to the body, micro-immunotherapy (MI) constitutes an interesting therapeutic strategy for the management of the atopic march and its symptoms. One of the aims of this review is to shed light on the current concept of the atopic march and the underlying immune reactions occurring during the IgE-mediated responses. Moreover, the different classes of traditional and innovative treatments employed in allergic diseases will also be discussed, with a special emphasis on the potential benefits of the MI medicine 2LALERG^® formulation in this context.

Reflectance Confocal Microscopy in Monitoring Atopic Dermatitis Treated with Topical Calcineurin Inhibitors

Atopic dermatitis is a chronic inflammatory skin disease associated with multiple allergies in the atopic march. It has a complex pathogenesis, related to genetic, immune, and environmental factors. Its incidence and prevalence are increasing in the last decades, especially in developed countries. It affects the quality of life due to the recurrent lesions and the associated pruritus. Thus, it is very important to use non-invasive techniques to manage and follow-up the patients with such a heterogenous disease that can have a high impact on some of them. The reflectance confocal microscope is a modern device for in vivo visualization of the epidermis and the upper dermis which could replace in some cases the cutaneous biopsy. We report a case of a patient with atopic dermatitis investigated with the confocal reflectance microscope at the beginning of the topical treatment with calcineurin inhibitors and three weeks after, with favorable evolution. Reflectance confocal microscopy allows the assessment of the dynamic changes in the skin during treatment. Moreover, it can be useful for highlighting discrete changes even in the subclinical stages of the inflammatory process. Future developments, which will lead to the definition and validation of reflectance confocal microscopy criteria for the diagnosis and staging of atopic dermatitis, could help to improve the treatment and prevention strategies of the disease.

Localized Delivery of Bioactives using Structured Liposomal Gels

Liposomes have gained a lot of interest for drug delivery applications, and some of these preparations have been commercialized. These are formulated with biocompatible components and can be used for delivering a wide range of payloads differing in aqueous solubility and molecular weight. Liposome-based delivery approaches are limited mainly by two factors: (a) poor dispersion stability, and (b) pre-mature leakage of payloads. In this review, we have discussed the stabilization of liposomal vesicles by their entrapment in hydrogels. Studies reveal that such hydrogels can maintain the structural integrity of liposomes. Release of liposomes from the hydrogel network can be modulated through careful screening of matrix former and degree of its cross-linking. Accordingly, we have reviewed the approaches of stabilizing liposomal vesicles through entrapment in hydrogels. Application of liposome-embedded hydrogels has been reviewed in context of localized drug delivery. Our discussion is focussed on the delivery of bioactives to the skin. Such an approach appears alluring from the standpoint of minimizing the undesirable distribution of payload(s) the systemic circulation and off-target sites.

Molecular networks in atopic mothers impact the risk of infant atopy

BACKGROUND

The prevalence of atopic diseases has increased with atopic dermatitis (AD) as the earliest manifestation. We assessed if molecular risk factors in atopic mothers influence their infants' susceptibility to an atopic disease.

METHODS

Pregnant women and their infants with (n = 174, high-risk) or without (n = 126, low-risk) parental atopy were enrolled in a prospective birth cohort. Global differentially methylated regions (DMRs) were determined in atopic (n = 92) and non-atopic (n = 82) mothers. Principal component analysis was used to predict atopy risk in children dependent on maternal atopy. Genome-wide transcriptomic analyses were performed in paired atopic (n = 20) and non-atopic (n = 15) mothers and cord blood. Integrative genomic analyses were conducted to define methylation-gene expression relationships.

RESULTS

Atopic dermatitis was more prevalent in high-risk compared to low-risk children by age 2. Differential methylation analyses identified 165 DMRs distinguishing atopic from non-atopic mothers. Inclusion of DMRs in addition to maternal atopy significantly increased the odds ratio to develop AD in children from 2.56 to 4.26. In atopic compared to non-atopic mothers, 139 differentially expressed genes (DEGs) were identified significantly enriched of genes within the interferon signaling pathway. Expression quantitative trait methylation analyses dependent on maternal atopy identified 29 DEGs controlled by 136 trans-acting methylation marks, some located near transcription factors. Differential expression for the same nine genes, including MX1 and IFI6 within the interferon pathway, was identified in atopic and non-atopic mothers and high-risk and low-risk children.

CONCLUSION

These data suggest that in utero epigenetic and transcriptomic mechanisms predominantly involving the interferon pathway may impact and predict the development of infant atopy.

Scientific and Practical Innovations in Restoring Skin Barrier Properties in Children with Atopic Dermatitis

Atopic dermatitis (AD) is a multifactorial inflammatory skin disease. Its pathogenetic basis is epidermal barrier dysfunction, immune system dysregulation, as well as skin microbiome diversity decrease that occurs due to genetic predisposition. Considering these factors, the skin of patients with AD requires constant care and use of medications with active regenerative properties. The inclusion of anti-inflammatory components in the composition of modern emollients (zinc sulfate and sucralfate) is crucial for restoring the microbiome and immune mechanisms controlling the skin. This article presents data on pathogenetic applicability and clinical efficacy of emollients with anti-inflammatory compounds in patients with AD.

Methylation risk scores for childhood aeroallergen sensitization: Results from the LISA birth cohort

BACKGROUND

Epigenomic (e.g., DNA methylation [DNAm]) changes have been hypothesized as intermediate step linking environmental exposures with allergic disease. Associations between individual DNAm at CpGs and allergic diseases have been reported, but their joint predictive capability is unknown.

METHODS

Data were obtained from 240 children of the German LISA cohort. DNAm was measured in blood clots at 6 (N = 234) and 10 years (N = 227) using the Illumina EPIC chip. Presence of aeroallergen sensitization was measured in blood at 6, 10, and 15 years. We calculated six methylation risk scores (MRS) for allergy-related phenotypes, like total and specific IgE, asthma, or any allergies, based on available publications and assessed their performances both cross-sectionally (biomarker) and prospectively (predictor of the disease). Dose-response associations between aeroallergen sensitization and MRS were evaluated.

RESULTS

All six allergy-related MRS were highly correlated (r > .86), and seven CpGs were included in more than one MRS. Cross-sectionally, we observed an 81% increased risk for aeroallergen sensitization at 6 years with an increased MRS by one standard deviation (best-performing MRS, 95% confidence interval = [43%; 227%]). Significant associations were also seen cross-sectionally at 10 years and prospectively, though the effect of the latter was attenuated when restricted to participants not sensitized at baseline. A clear dose-response relationship with levels of aeroallergen sensitization could be established cross-sectionally, but not prospectively.

CONCLUSION

We found good classification and prediction capabilities of calculated allergy-related MRS cross-sectionally, underlining the relevance of altered gene-regulation in allergic diseases and providing insights into potential DNAm biomarkers of aeroallergen sensitization.

The intestinal microbiome and the role of probiotics/prebiotics in the therapeutic approach of atopic dermatitis: A review

Atopic dermatitis (AD) is the most common chronic inflammatory skin condition, characterized by multiple recurrent eczematous lesions and intense itchiness. It is a multifactorial skin disorder involving an association between genetic and environmental factors that lead to a defect of the epithelial barrier in conjunction with immunological dysregulation. Over the last decade, there has been an increasing understanding of the role of the human microbiota in preserving skin integrity and that a shift in the homeostasis of these microorganisms may lead to dysbiosis and disease. Diversity in the intestinal microbiome and its role in the etiopathogenesis of AD has been described and has become of great interest. In this report, we have reviewed the importance of the gut microbiome and the possible mechanism in the pathogenesis of AD as well as the therapeutic impact of probiotics and prebiotics

Probiotics: Protecting Our Health from the Gut

The gut microbiota (GM) comprises billions of microorganisms in the human gastrointestinal tract. This microbial community exerts numerous physiological functions. Prominent among these functions is the effect on host immunity through the uptake of nutrients that strengthen intestinal cells and cells involved in the immune response. The physiological functions of the GM are not limited to the gut, but bidirectional interactions between the gut microbiota and various extraintestinal organs have been identified. These interactions have been termed interorganic axes by several authors, among which the gut-brain, gut-skin, gut-lung, gut-heart, and gut-metabolism axes stand out. It has been shown that an organism is healthy or in homeostasis when the GM is in balance. However, altered GM or dysbiosis represents a critical factor in the pathogenesis of many local and systemic diseases. Therefore, probiotics intervene in this context, which, according to various published studies, allows balance to be maintained in the GM, leading to an individual's good health.

Epigenetic Mechanisms of Epidermal Differentiation

Keratinocyte differentiation is an essential process for epidermal stratification and stratum corneum formation. Keratinocytes proliferate in the basal layer of the epidermis and start their differentiation by changing their functional or phenotypical type; this process is regulated via induction or repression of epidermal differentiation complex (EDC) genes that play a pivotal role in epidermal development. Epidermal development and the keratinocyte differentiation program are orchestrated by several transcription factors, signaling pathways, and epigenetic regulators. The latter exhibits both activating and repressive effects on chromatin in keratinocytes via the ATP-dependent chromatin remodelers, histone demethylases, and genome organizers that promote terminal keratinocyte differentiation, and the DNA methyltransferases, histone deacetylases, and Polycomb components that stimulate proliferation of progenitor cells and inhibit premature activation of terminal differentiation-associated genes. In addition, microRNAs are involved in different processes between proliferation and differentiation during the program of epidermal development. Here, we bring together current knowledge of the mechanisms controlling gene expression during keratinocyte differentiation. An awareness of epigenetic mechanisms and their alterations in health and disease will help to bridge the gap between our current knowledge and potential applications for epigenetic regulators in clinical practice to pave the way for promising target therapies.

Neuro-immune communication regulating pruritus in atopic dermatitis

Atopic dermatitis (AD) is a common, chronic-relapsing inflammatory skin disease with significant disease burden. Genetic and environmental trigger factors contribute to AD, activating two of our largest organs, the nervous and immune system. Dysregulation of neuro-immune circuits plays a key role in the pathophysiology of AD causing inflammation, pruritus, pain, and barrier dysfunction. Sensory nerves can be activated by environmental or endogenous trigger factors transmitting itch stimuli to the brain. Upon stimulation, sensory nerve endings also release neuromediators into the skin contributing again to inflammation, barrier dysfunction and itch. Additionally, dysfunctional peripheral and central neuronal structures contribute to neuroinflammation, sensitization, nerve elongation, neuropathic itch, thus chronification and therapy-resistance. Consequently, neuro-immune circuits in skin and central nervous system may be targets to treat pruritus in AD. Cytokines, chemokines, proteases, lipids, opioids, ions excite/sensitize sensory nerve endings not only induce itch but further aggravate/perpetuate inflammation, skin barrier disruption, and pruritus. Thus, targeted therapies for neuro-immune circuits as well as pathway inhibitors (e.g., kinase inhibitors) may be beneficial to control pruritus in AD either in systemic and/or topical form. Understanding neuro-immune circuits and neuronal signaling will optimize our approach to control all pathological mechanisms in AD, inflammation, barrier dysfunction and pruritus.

Associations between child filaggrin mutations and maternal diet with the development of allergic diseases in children

BACKGROUND

Filaggrin (FLG) loss-of-function mutations in children and maternal diet in pregnancy have been implicated in child allergy outcomes. This paper studies the questions: "do FLG mutations modify the effect of maternal diet on the odds of development of allergic diseases?" and "which factor leads to the highest rate of diagnosis allergic diseases over time, maternal diet, or FLG mutations?".

METHODS

Exact logistic regressions studied effect modification. Cox proportional hazard models compared the rate of allergic disease development in three groups (N = 624): (1) children with FLG mutation, (2) children without FLG mutation whose mothers did not eat an allergy preventive diet, and (3) children without FLG mutation whose mothers ate an allergy preventive diet. Maternal diet was classified using a validated index.

RESULTS

Cox models showed the development of atopic dermatitis, asthma, and wheeze was significantly higher for children in group 1 versus 3 (HR = 2.40 [1.32, 4.37], HR = 2.29 [1.05, 4.97], and HR 2.10 [1.004, 4.38], respectively), but not significantly higher for children in group 1 versus 2 (HR = 1.30 [0.74, 2.29], HR = 1.27 [0.61, 2.63], and HR = 1.29 [0.65, 2.58], respectively). Development of allergic rhinitis was significantly higher for group 1 versus 2 and 3 (1 vs. 2: HR = 2.29 [1.10, 4.76]; 1 vs. 3: HR = 3.21 [1.46, 7.08]). There was no significant effect modification for any outcome.

CONCLUSION

Children with FLG mutation had similar risk of atopic dermatitis, asthma, and wheeze as children without an FLG mutation whose mothers did not eat an allergy preventive diet during pregnancy. Child FLG mutation did not modify the effect of maternal diet. The results suggest that maternal diet in pregnancy, a modifiable risk factor, could be a target for preventive interventions.

Novel role for caspase recruitment domain family member 14 and its genetic variant rs11652075 in skin filaggrin homeostasis

BACKGROUND

Low epidermal filaggrin (FLG) is a risk factor for atopic dermatitis (AD) and allergic comorbidity. FLG mutations do not fully explain the variation in epidermal FLG levels, highlighting that other genetic loci may also regulate FLG expression.

OBJECTIVE

We sought to identify genetic loci that regulate FLG expression and elucidate their functional and mechanistic consequences.

METHODS

A genome-wide association study of quantified skin FLG expression in lesional and baseline non(never)-lesional skin of children with AD in the Mechanisms of Progression of Atopic Dermatitis to Asthma in Children cohort was conducted. Clustered regularly interspaced short palindromic repeat approaches were used to create isogenic human keratinocytes differing only at the identified variant rs11652075, and caspase recruitment domain family member 14 (CARD14)-deficient keratinocytes for subsequent mechanistic studies.

RESULTS

The genome-wide association study identified the CARD14 rs11652075 variant to be associated with FLG expression in non(never)-lesional skin of children with AD. Rs11652075 is a CARD14 expression quantitative trait locus in human skin and primary human keratinocytes. The T variant destroys a functional cytosine-phosphate-guanine site, resulting in reduced cytosine-phosphate-guanine methylation at this site (but not neighboring sites) in TT and CT compared with CC primary human keratinocytes and Mechanisms of Progression of Atopic Dermatitis to Asthma in Children children's skin samples, and rs11652075 increases CARD14 expression in an allele-specific fashion. Furthermore, studies in clustered regularly interspaced short palindromic repeat-generated CC and TT isogenic keratinocytes, as well as CARD14-haplosufficient and deficient keratinocytes, reveal that IL-17A regulates FLG expression via CARD14, and that the underlying mechanisms are dependent on the rs11652075 genotype.

CONCLUSIONS

Our study identifies CARD14 as a novel regulator of FLG expression in the skin of children with AD. Furthermore, CARD14 regulates skin FLG homeostasis in an rs11652075-dependent fashion.

The Skin and Nose Microbiome and Its Association with Filaggrin Gene Mutations in Pediatric Atopic Dermatitis

Background

Interactions between the skin barrier, immune system, and microbiome underlie the development of atopic dermatitis (AD).

Objective

To investigate the skin and nasal microbiome in relation to filaggrin gene (FLG) mutations.

Methods

A cross-sectional study including 77 children with difficult-to-treat AD. The entire encoding region of FLG was screened for mutations using single molecule molecular inversion probes and next-generation sequencing. Bacterial swabs from the anterior nares, lesional and nonlesional skin were analyzed using 16S rRNA sequencing. For skin samples, additional qPCR was performed for Staphylococcus aureus and Staphylococcus epidermidis.

Results

The prevalence of patients with a mutation in FLG was 40%, including 10 different mutations. Analyzing bacterial swabs from all three niches showed a significant effect for both niche and FLG mutation status on the overall microbiome composition. Using a subset analysis to test the effect of FLG mutation status per niche separately did not show a significant association to the microbiome. Shannon diversity and S. aureus abundance were significantly affected by the niche, but not by the presence of an FLG mutation.

Conclusions

Our results suggest only a minor role for FLG mutation status on the overall microbiome, which is rather caused by differences in the present genera than by microbe richness and evenness.

Overcoming drug delivery barriers and challenges in topical therapy of atopic dermatitis: A nanotechnological perspective

Atopic dermatitis (AD) is an inflammatory disorder centered around loss of epidermal barrier function, and T helper 2 (Th2) immune responses. The current understanding of disease heterogeneity and complexity, limits the rational use of existing topical, systemic therapeutic agents, but paves way for development of advanced therapeutic agents. Additionally, advanced nanocarriers that deliver therapeutics to target cells, seem to offer a promising strategy, to overcome intrinsic limitations and challenges of conventional, and traditional drug delivery systems. Ever-evolving understanding of molecular target sites and complex pathophysiology, adverse effects of current therapeutic options, inefficient disease recapitulation by existing animal models are some of the challenges that we face. Also, despite limited success in market translatibility, nanocarriers have demonstrated excellent preclinical results and have been extensively studied for AD. Detailed research on behavior of nanocarriers in different patients and tailored therapy to account for phenotypic variability of the disease are the new research avenues that we look forward to.

Challenges and Opportunities for the Translation of Single-Cell RNA Sequencing Technologies to Dermatology

Skin is a complex and heterogeneous organ at the cellular level. This complexity is beginning to be understood through the application of single-cell genomics and computational tools. A large number of datasets that shed light on how the different human skin cell types interact in homeostasis-and what ceases to work in diverse dermatological diseases-have been generated and are publicly available. However, translation of these novel aspects to the clinic is lacking. This review aims to summarize the state-of-the-art of skin biology using single-cell technologies, with a special focus on skin pathologies and the translation of mechanistic findings to the clinic. The main implications of this review are to summarize the benefits and limitations of single-cell analysis and thus help translate the emerging insights from these novel techniques to the bedside.

Skin microbiome of atopic dermatitis

The skin microbiome is a key component of pathogenesis in atopic dermatitis (AD). The skin of AD patients is characterized by microbial dysbiosis, with a reduction of microbial diversity and overrepresentation of pathogenic Staphylococcus aureus (S. aureus). Recent exciting studies have elucidated an importance of establishing an appropriate immune response to microbes in early life and uncovered the new mechanisms of microbial community dynamics in modulating our skin microbiome. Several microbes are associated with AD pathogenesis, with proposed pathogenic effects from S. aureus and Malassezia. The complex relationships between microbes within the skin microbiome consortia includes various species, such as Staphylococcal, Roseomonas and Cutibacterium strains, that can inhibit S. aureus and are potential probiotics for AD skin. Numerous microbes are now also reported to modulate host response via communication with keratinocytes, specialized immune cells and adipocytes to improve skin health and barrier function. This increased understanding of skin microbiota bioactives has led to new biotherapeutic approaches that target the skin surface microenvironment for AD treatment.

Polygenic prediction of atopic dermatitis improves with atopic training and filaggrin factors

BACKGROUND

While numerous genetic loci associated with atopic dermatitis (AD) have been discovered, to date, work leveraging the combined burden of AD risk variants across the genome to predict disease risk has been limited.

OBJECTIVES

This study aims to determine whether polygenic risk scores (PRSs) relying on genetic determinants for AD provide useful predictions for disease occurrence and severity. It also explicitly tests the value of including genome-wide association studies of related allergic phenotypes and known FLG loss-of-function (LOF) variants.

METHODS

AD PRSs were constructed for 1619 European American individuals from the Atopic Dermatitis Research Network using an AD training dataset and an atopic training dataset including AD, childhood onset asthma, and general allergy. Additionally, whole genome sequencing data were used to explore genetic scoring specific to FLG LOF mutations.

RESULTS

Genetic scores derived from the AD-only genome-wide association studies were predictive of AD cases (PRSAD: odds ratio [OR], 1.70; 95% CI, 1.49-1.93). Accuracy was first improved when PRSs were built off the larger atopy genome-wide association studies (PRSAD+: OR, 2.16; 95% CI, 1.89-2.47) and further improved when including FLG LOF mutations (PRSAD++: OR, 3.23; 95% CI, 2.57-4.07). Importantly, while all 3 PRSs correlated with AD severity, the best prediction was from PRSAD++, which distinguished individuals with severe AD from control subjects with OR of 3.86 (95% CI, 2.77-5.36).

CONCLUSIONS

This study demonstrates how PRSs for AD that include genetic determinants across atopic phenotypes and FLG LOF variants may be a promising tool for identifying individuals at high risk for developing disease and specifically severe disease.

Recent Developments and Advances in Atopic Dermatitis: A Focus on Epidemiology, Pathophysiology, and Treatment in the Pediatric Setting

Atopic dermatitis (AD) is a chronic inflammatory skin disorder that affects a substantial number of children and has a significant negative impact on affected patients and their caregivers/families. Recent studies have led to significant evolutions in the understanding of AD pathogenesis, epidemiology, and treatment. The first point of contact for many patients with new-onset AD is usually with their primary care provider or pediatrician. This underscores the importance for pediatricians to understand the basic pathophysiology and current standards of care for AD. This article provides up-to-date information and reviews the basic principles of AD pathophysiology, diagnosis, and management. In addition, the article highlights recent advances in scientific research regarding the mechanisms involved in the pathogenesis of atopic dermatitis that have resulted in the discovery of novel therapeutic targets and the development of targeted biologic therapies with the potential to revolutionize AD therapy.

Barrier Impairment and Type 2 Inflammation in Allergic Diseases: The Pediatric Perspective

Allergic diseases represent a global burden. Although the patho-physiological mechanisms are still poorly understood, epithelial barrier dysfunction and Th2 inflammatory response play a pivotal role. Barrier dysfunction, characterized by a loss of differentiation, reduced junctional integrity, and altered innate defence, underpins the pathogenesis of allergic diseases. Epithelial barrier impairment may be a potential therapeutic target for new treatment strategies Up now, monoclonal antibodies and new molecules targeting specific pathways of the immune response have been developed, and others are under investigation, both for adult and paediatric populations, which are affected by atopic dermatitis (AD), asthma, allergic rhinitis (AR), chronic rhinosinusitis with nasal polyps (CRSwNP), or eosinophilic esophagitis (EoE). In children affected by severe asthma biologics targeting IgE, IL-5 and against IL-4 and IL-13 receptors are already available, and they have also been applied in CRSwNP. In severe AD Dupilumab, a biologic which inhibits both IL-4 and IL-13, the most important cytokines involved in inflammation response, has been approved for treatment of patients over 12 years. While a biological approach has already shown great efficacy on the treatment of severe atopic conditions, early intervention to restore epithelial barrier integrity, and function may prevent the inflammatory response and the development of the atopic march.

Nutrition and Water

Water has numerous functions necessary for survival including cellular homeostasis, solvent properties for dissolving ions and solutes, thermoregulation, and transport of waste and nutrients. Despite the established beneficial role of water in skin physiology, the optimal methods for skin hydration and requirements for daily water consumption remain elusive. This review summarizes the cellular and molecular biology of skin hydration, the debate and current recommendations of daily water requirements, and the latest research on interventions to improve skin hydration by both internal and external means of water exposure. We also explore the chemical properties of water, such as the concept of water "hardness" and environmental pollutants, and their impact on skin physiology.

Cosmetic Applications of Bee Venom

Bee venom (BV) is a typical toxin secreted by stingers of honeybee workers. BV and BV therapy have long been attractive to different cultures, with extensive studies during recent decades. Nowadays, BV is applied to combat several skin diseases, such as atopic dermatitis, acne vulgaris, alopecia, vitiligo, and psoriasis. BV is used extensively in topical preparations as cosmetics and used as dressing for wound healing, as well as in facemasks. Nevertheless, the safety of BV as a therapeutic choice has always been a concern due to the immune system reaction in some people due to BV use. The documented unfavorable impact is explained by the fact that the skin reactions to BV might expand to excessive immunological responses, including anaphylaxis, that typically resolve over numerous days. This review aims to address bee venom therapeutic uses in skin cosmetics.

Confirming the TMEM232 gene associated with atopic dermatitis through targeted capture sequencing

Atopic dermatitis (AD) is a common and complex skin disorder, and the 5q22.1 region had been reported to be associated with AD. To confirm the susceptibility gene for AD in the 5q22.1 region by haplotype and targeted capture sequencing. The haplotypes were reconstructed with the genotyping data of four SNPs and six deletions from 3624 Chinese Hans AD patients and 5076 controls. The targeted capture sequencing spanning 5q22.1 region was performed in the selected samples. The gene level enrichment analysis was done using loss of function variants. A total of 62 haplotypes were found, and the H15 haplotype had the strongest association with AD (P = 3.92 × 10^-10, OR 0.17, 95% CI 0.09-0.32). However, no co-segregation mutation sites were found in the sequencing analysis within the 16 selected samples, while the enrichment analysis indicated that TMEM232 was significantly associated with AD (P = 7.33 × 10^-5, OR 0.33, 95% CI 0.19-0.58). This study confirms previous findings that the TMEM232 gene is associated with AD by haplotype analysis and targeted capture sequencing.

What are the highest yielding search strategy terms for systematic reviews in atopic dermatitis? A systematic review

The impact of search strategies on systematic reviews (SR) of atopic dermatitis (AD) is unknown. The purpose of this review was to evaluate search strategies used in SR of AD and their impact on the frequency of manuscripts identified. MEDLINE and EMBASE were searched for SR related to AD. Simulations were performed by running combinations of search terms in MEDLINE and EMBASE. Overall, 250 SR met inclusion criteria, of which 225 specified search strategies. SR using 5-6 terms (20.0% to 12.1%) or ≥ 7 (40.0% to 18.8%) terms decreased, whereas SR using 3-4 terms numerically increased (18.8% to 30.2%) and 1-2 terms remained similar (37.5% to 38.9%) from 1999-2009 to 2015-2019. The most commonly searched terms were "atopic dermatitis" (n = 166), followed by "eczema" (n = 156), "dermatitis atopic'" (n = 81), "atopic eczema" (n = 74), "neurodermatitis" (n = 59), "Besniers prurigo" (n = 29), "infantile eczema" (n = 27), and "childhood eczema" (n = 19). Simulations revealed that "eczema" and "atopic dermatitis" yielded the most hits. The number of search terms that maximized hits in MEDLINE and EMBASE was 5 and 4, respectively. Search strategies for AD were heterogeneous, with high proportions of search strategies providing few search hits. Future studies should use standardized and optimized search terms.

Osteopontin Gene Polymorphisms rs1126616 C>T and rs1126772 A>G are Associated with Atopic Dermatitis in Polish Population

Purpose

Atopic dermatitis (AD) is a chronic, relapsing inflammatory disease, caused by environmental and genetic factors, which lead to immunological abnormalities. Osteopontin (OPN), also named secreted phosphoprotein 1 (SPP1), is a protein involved in the pathogenesis of numerous autoimmune and inflammatory conditions. However, its role in AD has not been fully elucidated. Therefore, we aim to gain an insight into the role of OPN in AD pathogenesis through investigating its gene single nucleotide polymorphisms (SNPs) and their possible associations with disease clinical features.

Patients and Methods

A total of 182 Caucasian participants (45 AD patients and 137 gender- and age-matched controls) were studied. Genomic DNA was isolated from peripheral blood samples. Genotyping for the rs1126616 C>T, rs1126772 A>G, rs9138 A>C, and rs3841116 T>G SNPs was performed by real time polymerase chain reaction (RT-PCR).

Results

The frequency of the minor TT genotype and the T allele of rs1126616 C>T was higher in AD patients compared to controls (P = 0.019, OD = 4.86, 95% CI = 1.46–16.20, and P = 0.047, OR = 1.77, 95% CI = 1.04–3.00, respectively) and was associated with the higher prevalence of asthma (P = 0.017, OR = 3.73, 95% CI = 0.71–19.67, and P = 0.004, OR = 3.96, 95% CI = 1.53–10.25, respectively). Likewise, the minor GG genotype and the G allele of rs1126772 A>G were more frequent in AD patients (P = 0.026, OR = 3.27, 95% CI = 1.29–8.33, and P = 0.013, OR = 1.94, 95% CI = 1.18–3.21, respectively) and were associated with the increased incidence of asthma (P = 0.016, OR = 5.06, 95% CI = 1.14–22.49, and P = 0.002, OR = 4.40, 95% CI = 1.71–11.35, respectively). Furthermore, haplotype frequency estimation determined the four-loci haplotype TGCT, as a significant risk factor for AD compared to controls (P = 0.031, OR = 9.48, 95% CI = 1.23–71.91).

Conclusion

Our results suggest that the variation in the OPN gene might be associated with AD and increased incidence of asthma in Caucasians. Further studies should be conducted to look into the possible role of OPN as a biomarker for AD.

Very Elevated IgE, Atopy, and Severe Infection: A Genomics-Based Diagnostic Approach to a Spectrum of Diseases

Elevated IgE has been long recognized as an important clinical marker of atopy but can be seen in a myriad of conditions. The discovery of autosomal dominant STAT3 deficiency marked the first recognition of hyper-IgE syndrome (HIES) and the first primary immunodeficiency linked to elevated IgE. Since then, genomic testing has increased the number of defects with associated mutations causing hyper-IgE syndrome and atopic diseases with FLG, DOCK8, SPINK5, and CARD11, among others. A spectrum of recurrent infections and atopy are hallmarks of elevated IgE with significant phenotypic overlap between each underlying condition. As treatment is predicated on early diagnosis, genomic testing is becoming a more commonly used diagnostic tool. We present a 6-year-old male patient with markedly elevated IgE and severe atopic dermatitis presenting with staphylococcal bacteremia found to have a heterozygous variant in FLG (p.S3247X) and multiple variants of unknown significance in BCL11B, ZAP70, LYST, and PTPRC. We review the genetic defects underpinning elevated IgE and highlight the spectrum of atopy and immunodeficiency seen in patients with underlying mutations. Although no one mutation is completely causative of the constellation of symptoms in this patient, we suggest the synergism of these variants is an impetus of disease.