High-density genotyping study identifies four new susceptibility loci for atopic dermatitis

Update on the genetics of allergic diseases

The field of genetic etiology of allergic diseases has advanced significantly in recent years. Shared risk loci reflect the contribution of genetic factors to the sequential development of allergic conditions across the atopic march, while unique risk loci provide opportunities to understand tissue specific manifestations of allergic disease. Most identified risk variants are noncoding, indicating that they likely influence gene expression through gene regulatory mechanisms. Despite recent advances, challenges persist, particularly regarding the need for increased ancestral diversity in research populations. Further, while polygenic risk scores show promise for identifying individuals at higher genetic risk for allergic diseases, their predictive accuracy varies across different ancestries and can be difficult to translate to an individual's absolute risk of developing a disease. Methodologies, including "nearest gene," 3D chromatin interaction analysis, expression quantitative trait locus analysis, experimental screens, and integrative bioinformatic models, have established connections between genetic variants and their regulatory targets, enhancing our understanding of disease risk and phenotypic variability. In this review, we focus on the state of knowledge of allergic sensitization and 5 allergic diseases: asthma, atopic dermatitis, allergic rhinitis, food allergy, and eosinophilic esophagitis. We summarize recent progress and highlight opportunities for advancing our understanding of their genetic etiology.

Causal association between allergic diseases and celiac disease: a bidirectional two-sample and multivariable Mendelian-randomization study

OBJECTIVE

This study aimed to assess the causality of allergic diseases and celiac disease.

METHODS

We collected summary-level data from publicly available genome-wide association studies to conduct our bidirectional two-sample and multivariable Mendelian randomization analysis. Furthermore, a series of sensitivity analyses were applied to validate our findings.

RESULTS

In bidirectional two-sample MR analyses, we found a significant causal effect of atopic dermatitis (AD) on CD (Inverse-variance weighted (IVW): odds ratio [OR] = 1.302, 95% confidence interval [CI] = 1.152-1.471, p < 0.001). We also found a significant causal effect of allergic rhinitis (AR) on CD (IVW: OR = 4.181, 95% CI = 1.495-11.697, p = 0.006). However, the MR-Egger method indicated a different causal effect direction compared to the IVW and weighted median method. After Bonferroni correction, the result of asthma on CD is suggestive of a causal effect (IVW: OR = 1.186, 95% CI = 1.021-1.378, p = 0.026). No causal effects were found when CD was considered as an exposure variable. In MVMR analyses, after separately and jointly adjusting for the influence of smoking and BMI, the causal effect of AD on CD remained robust.

CONCLUSIONS

Our study suggests that AD is a risk factor for CD and it is considered suggestive of a causal relationship between asthma and CD. Further research is needed to explore the potential mechanisms underlying this causal effect.

IL-9 sensitizes human TH2 cells to proinflammatory IL-18 signals in atopic dermatitis

BACKGROUND

TH2 cells crucially contribute to the pathogenesis of atopic dermatitis (AD) by secreting high levels of IL-13 and IL-22. Yet the upstream regulators that activate TH2 cells in AD skin remain unclear. IL-18 is a putative upstream regulator of TH2 cells because it is implicated in AD pathogenesis and has the capacity to activate T cells.

OBJECTIVE

We sought to decipher the role of IL-18 in TH2 responses in blood and skin of AD patients.

METHODS

Peripheral blood mononuclear cells and skin biopsy samples from AD patients and healthy donors were used. Functional assays were performed ex vivo using stimulation or blocking experiments. Analysis was performed by flow cytometry, bead-based multiplex assays, RT-qPCR, RNA-Seq, Western blot, and spatial sequencing.

RESULTS

IL-18Rα+ TH2 cells were enriched in blood and lesional skin of AD patients. Of all the cytokines for which TH2 cells express the receptor, only IL-9 was able to induce IL-18R via an IL-9R-JAK1/JAK3-STAT1 signaling pathway. Functionally, stimulation of circulating TH2 cells with IL-18 induced secretion of IL-13 and IL-22, an effect that was enhanced by costimulation with IL-9. Mechanistically, IL-18 induced TH2 cytokines via activation of IRAK4, NF-κB, and AP-1 signaling in TH2 cells, and neutralization of IL-18 inhibited these cytokines in cultured explants of AD skin lesions. Finally, IL-18 protein levels correlated positively with disease severity in lesional AD skin.

CONCLUSION

Our data identify a novel IL-9/IL-18 axis that contributes to TH2 responses in AD. Our findings suggest that both IL-9 and IL-18 could represent upstream targets for future treatment of AD.

Concurrent Refractory Atopic Dermatitis and Generalized Vitiligo Successfully Treated with Abrocitinib: A Case Report

Atopic dermatitis (AD) may sometimes be comorbid with vitiligo. However, these therapeutic agents are often slow acting and lead to various adverse effects, resulting in poor patient compliance. This report describes a 65-year-old male patient with refractory moderate-to-severe atopic dermatitis (AD) and generalized vitiligo. The patient was treated with repeated antihistamine and dupilumab injections; however, erythema and pruritus did not improve. Consequently, oral abrocitinib was administered to treat AD and vitiligo, and the patient's generalized erythema, papules, and pruritus ameliorated with the repigmentation of vitiligo lesions. This case provided evidence of the efficacy and safety of oral abrocitinib for patients with concurrent refractory AD and vitiligo.

The Association Between Atopic Dermatitis and Inflammatory Bowel Disease Risk: A Meta-Analysis of Longitudinal Studies

Aims

This review aimed to investigate whether atopic dermatitis (AD) increases the risk of inflammatory bowel disease (IBD) by analyzing data from longitudinal studies.

Methods

Cohort and case-control studies evaluating the association between AD and the risk of IBD, Crohn's disease (CD), or ulcerative colitis (UC) were included. Literature searches were conducted in PubMed, CENTRAL, Embase, Scopus, and Web of Science databases up to April 15, 2024.

Results

A total of eight retrospective cohort studies comprising 61 190 816 participants were included. Meta-analysis revealed that AD significantly increased the risk of IBD (OR: 1.37, 95% CI: 1.31-1.43) without statistical heterogeneity. Further pooled analysis showed that AD was a significant risk factor for CD (OR: 1.51, 95% CI: 1.31-1.76) and UC (OR: 1.33, 95% CI: 1.13-1.56), with high inter-study heterogeneity (I 2 = 83% and 89%, respectively). Sensitivity analyses confirmed the robustness of the results.

Conclusion

AD is associated with an increased risk of IBD, significantly elevating the risk of both CD and UC.

Chimeric antigens displaying GPR65 extracellular loops on a soluble scaffold enabled the discovery of antibodies, which recognized native receptor

GPR65 is a proton-sensing G-protein coupled receptor associated with multiple immune-mediated inflammatory diseases, whose function is relatively poorly understood. With few reagents commercially available to probe the biology of receptor, generation of an anti-GPR65 monoclonal antibody was desired. Using soluble chimeric scaffolds, such as ApoE3, displaying the extracellular loops of GPR65, together with established phage display technology, native GPR65 loop-specific antibodies were identified. Phage-derived loop-binding antibodies recognized the wild-type native receptor to which they had not previously been exposed, generating confidence in the use of chimeric soluble proteins to act as efficient surrogates for membrane protein extracellular loop antigens. This technique provides promise for the rational design of chimeric antigens in facilitating the discovery of specific antibodies to GPCRs.

Joint genotype and ancestry analysis identify novel loci associated with atopic dermatitis in African American population

Atopic dermatitis (AD) is a chronic itchy inflammatory disease of the skin. Genetic studies have identified multiple risk factors linked to the disease; however, most of the studies have been derived from European and East Asian populations. The admixed African American (AA) genome may provide an opportunity to discovery ancestry-specific loci involved in AD susceptibility. Herein, we present joint analysis of ancestry and genotype effects followed by validation using differential gene expression analysis on AD using 726 AD-affected individuals and 999 non-AD control individuals from the AA population, genotyped using Multi-Ethnic Global Array (MEGA) followed by imputation using the Consortium on Asthma among African Ancestry Populations in the Americas (CAAPA) reference panel. The joint analysis identified two novel AD-susceptibility loci, rs2195989 in gene ANGPT1 (8q23.1) and rs62538818 in the intergenic region between genes LURAP1L and MPDZ (9p23). Admixture mapping (AM) results showed potential genomic inflation, and we implemented genomic control and identified five ancestry-of-origin loci with European ancestry effects. The multi-omics functional prioritization of variants in AM signals prioritized the loci SLAIN2, RNF39, and FOXA2. Genome-wide association study (GWAS) identified variants significantly associated with AD in the AA population, including SGK1 (rs113357522, odds ratio [OR] = 2.81), EFR3A (rs16904552, OR = 1.725), and MMP14 (rs911912, OR = 1.791). GWAS variants were common in the AA but rare in the European population, which suggests an African-ancestry-specific risk of AD. Four genes (ANGPT1, LURAP1L, EFR3A, and SGK1) were further validated using qPCR from AD and healthy skin. This study highlighted the importance of genetic studies on admixed populations, as well as local ancestry and genotype-ancestry joint effects to identify risk loci for AD.

Association of Wheezing Requiring Hospitalization Before 2 Years of Age With Autoimmune Diseases During Childhood: A 15-Year Follow-up Study From Birth

PURPOSE

Wheezing in early life is most frequently caused by viral lower respiratory tract illnesses, constituting a significant disease burden in children. This study aimed to investigate the association of wheezing in early life with autoimmune diseases throughout childhood.

METHODS

A population-matched retrospective cohort study was conducted in Korea between 2002 and 2017. The cohort comprised 34,959 children admitted with viral wheezing before 2 years of age and an equal number of the matched unexposed children born in 2002 and 2003. Exposed infants were defined as those hospitalized for bronchiolitis or bronchial asthma before the age of 2. Unexposed controls were matched by sex and birth year at a 1:1 ratio, using incidence density sampling. A Cox proportional hazard model controlled for multiple risk factors was employed.

RESULTS

The median age at hospitalization for wheeze was 9 months (interquartile range, 5-15 months), and 63% of the exposed infants were male. Over the mean 15-year follow-up period, the incidence rate of autoimmune diseases was 74.0 and 62.2 per 10,000 person-years in the exposed and matched unexposed cohorts, respectively. The adjusted hazard ratio for any autoimmune disease in the exposed cohort was 1.15 (95% confidence interval, 1.09-1.23) in comparison with the unexposed cohort. The exposed cohort revealed an augmented risk for specific autoimmune diseases, including juvenile idiopathic arthritis, Kawasaki disease, Henoch-Schönlein purpura, psoriasis, idiopathic thrombocytopenic purpura, and immunoglobulin A nephropathy. Risks were heightened for children with multiple wheezing episodes or a persistent wheezing episode after the age of 2 years.

CONCLUSIONS

This research identifies associations between early-life wheeze and the development of autoimmune diseases in childhood. Understanding these relationships can aid in recognizing the underlying pathophysiology of early-life wheeze and childhood autoimmune diseases, contributing to management strategies for these conditions.

A genome-wide association study of hand eczema identifies locus 20q13.33 and reveals genetic overlap with atopic dermatitis

BACKGROUND

Twin studies revealed that genetic effects play a role in hand eczema (HE), but the responsible genetic factors are unknown.

OBJECTIVES

To identify and characterise genetic loci associated with HE and to provide insight into the genetic overlap between HE and atopic dermatitis (AD).

METHODS

We used questionnaire-derived and genotype data from the European population-based Lifelines cohort and biobank. We performed a discovery genome-wide association study (GWAS) of HE (2879 cases and 16 249 controls) and of AD (1706 cases and 17 190 controls). We replicated our findings in an independent Lifelines sample for HE (1188 cases and 6431 controls) and AD (757 cases and 6747 controls). We conducted several post-GWAS analyses and performed genetic correlation analyses between our HE results and independent AD data.

RESULTS

The two-step GWAS of HE, regardless of adjusting for AD, identified one independent locus 20q13.33, likely driven by a number of causal single-nucleotide polymorphisms. For the AD GWAS, we replicated a known stop-gained rs61816761 at locus 1q21.3 (FLG, FLGAS1). We found a strong genetic correlation (p < 0.01) between HE and AD (rg = 0.65), regardless of adjusting for AD (rg = 0.63).

CONCLUSIONS

Locus 20q13.33 is associated with HE, and there is a large genetic overlap between HE and AD.

Exploring novel drug targets for atopic dermatitis through plasma proteome with genome

Atopic dermatitis (AD) is a chronic inflammatory disease with a complex and heterogeneous clinical presentation, leading to treatment limitations. Therefore, there is an urgent demand for new therapeutic drug targets. This study utilized Summary-data-based Mendelian randomization (SMR) to identify potential drug targets for AD. Summary statistics for 2,940 human plasma proteins were obtained from the UK Biobank, while AD statistics came from the Early Genetics and Epidemiology of Life Processes consortium and the FinnGen consortium. Furthermore, subsequent colocalization analyses confirmed the causal roles of candidate proteins. Moreover, Phenome-Wide Association Studies (PheWAS), protein-protein interaction (PPI), enrichment analysis, and single cell-type expression analysis provided additional insights. Additionally, drug prediction, druggability prediction, and molecular docking informed the discovery of novel drug targets. SMR analysis showed that eight plasma proteins were causally associated with AD: PVALB and TST were associated with a reduced risk of AD, while CA14, ECM1, IL22, IL6R, IL18R1, and MMP12 were associated with an increased risk of AD. Colocalization analysis confirmed significant associations for TST, IL22, and CA14. PheWAS further revealed that candidate drug targets were mainly linked to other allergic diseases. The corresponding protein-coding genes are predominantly expressed in melanocytes, T cells, and macrophages in skin tissue. Importantly, these proteins were identified to be involved in cytokine-cytokine receptor interaction, Th17 cell differentiation, and the JAK-STAT signaling pathway. All of these proteins are druggable, and six of them show great potential as drug targets. In conclusion, this study identified eight plasma proteins causally associated with AD and provided new insights into the etiology and potential drug targets for AD.

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.

Two-sample Mendelian randomization analysis of causal relationship between eczema and autoimmune diseases

OBJECTIVES

The causal relationship between eczema and autoimmune diseases has not been previously reported. This study aims to evaluate the causal relationship between eczema and autoimmune diseases.

METHODS

The two-sample Mendelian randomization (MR) method was used to assess the causal effect of eczema on autoimmune diseases. Summary data from the Genome-Wide Association Study Catalog (GWAS) were obtained from the Integrative Epidemiology Unit (IEU) database. For eczema and autoimmune diseases, genetic instrument variants (GIVs) were identified according to the significant difference (P<5×10-8). Causal effect estimates were generated using the inverse-variance weighted (IVW) method. MR Egger, maximum likelihood, MR-PRESSO, and MR-RAPS methods were used for alternative analyses. Sensitivity tests, including heterogeneity, horizontal pleiotropy, and leave-one-out analyses, were performed. Finally, reverse causality was assessed.

RESULTS

Genetic susceptibility to eczema was associated with an increased risk of Crohn's disease (OR=1.444, 95% CI 1.199 to 1.738, P<0.001) and ulcerative colitis (OR=1.002, 95% CI 1.001 to 1.003, P=0.002). However, no causal relationship was found for the other 6 autoimmune diseases, including systemic lupus erythematosus (SLE) (OR=0.932, P=0.401), bullous pemphigoid (BP) (OR=1.191, P=0.642), vitiligo (OR=1.000, P=0.327), multiple sclerosis (MS) (OR=1.000, P=0.965), ankylosing spondylitis (AS) (OR=1.001, P=0.121), rheumatoid arthritis (RA) (OR=1.000, P=0.460). Additionally, no reverse causal relationship was found between autoimmune diseases and eczema.

CONCLUSIONS

Eczema is associated with an increased risk of Crohn's disease and ulcerative colitis. No causal relationship is found between eczema and SLE, MS, AS, RA, BP, or vitiligo.

Association Between Atopic Dermatitis and Aging: Clinical Observations and Underlying Mechanisms

As one of the most prevalent chronic inflammatory skin diseases, atopic dermatitis (AD) increasingly affects the aging population. Amid the ongoing global aging trend, it's essential to recognize the intricate relationship between AD and aging. This paper reviews existing knowledge, summarizing clinical observations of associations between AD and aging-related diseases in various systems, including endocrine, cardiovascular, and neurological. Additionally, it discusses major theories explaining the correlation, encompassing skin-mucosal barriers, systemic inflammation and stress, genes, signal transduction, and environmental and behavioral factors. The association between AD and aging holds significant importance, both in population and basic perspectives. While further research is warranted, this paper aims to inspire deeper exploration of inflammation/allergy-aging dynamics and the timely management of elderly patients with AD.

Adding Fuel to the Fire? The Skin Microbiome in Atopic Dermatitis

Atopic dermatitis (AD) is a multifactorial, heterogeneous disease characterized by epidermal barrier dysfunction, immune system dysregulation, and skin microbiome alterations. Skin microbiome studies in AD have demonstrated that disease flares are associated with microbial shifts, particularly Staphylococcus aureus predominance. AD-associated S. aureus strains differ from those in healthy individuals across various genomic loci, including virulence factors, adhesion proteins, and proinflammatory molecules-which may contribute to complex microbiome barrier-immune system interactions in AD. Different microbially based treatments for AD have been explored, and their future therapeutic successes will depend on a deeper understanding of the potential microbial contributions to the disease.

Genetic and Immunological Pathogenesis of Atopic Dermatitis

Type 2 immune-mediated diseases give a clear answer to the issue of nature (genetics) versus nurture (environment). Both genetics and environment play vital complementary roles in the development of atopic dermatitis (AD). As a key component of the atopic march, AD demonstrates the interactive nature of genetic and environmental contributions to atopy. From sequence variants in the epithelial barrier gene encoding FLG to the hygiene hypothesis, AD combines a broad array of contributions into a single syndrome. This review will focus on the genetic contribution to AD and where genetics facilitates the elicitation or enhancement of AD pathogenesis.

Genome-wide Association Study of Susceptibility Loci for Self-Reported Atopic Dermatitis and Allergic Rhinitis in the Korean Population

BACKGROUND

Allergic diseases include atopic dermatitis (AD) and allergic rhinitis (AR), which are chronic, relapsing inflammatory disorders of the skin or mucosa that usually accompany immunoglobulin E-mediated immune responses. They are complex, multifactorial diseases with an etiology involving interactions between genetic and environmental factors.

OBJECTIVE

We performed a genome-wide association study (GWAS) to identify single nucleotide polymorphisms (SNPs) associated with allergic diseases in the Korean population.

METHODS

A total of 8,840 samples were obtained from the Korean Association Resource Consortium dataset of the Korean Genome and Epidemiology Study Ansan-Anseong cohort. The allergic disease phenotype was determined based on self-reported physician diagnoses. After quality control, 8,823 subjects with 877,242 variants remained for the final analysis. The GWAS was performed using logistic regression analysis in an additive model adjusted for age and sex.

RESULTS

A total of 636 patients with allergic disease and 8,176 controls were analyzed. Three SNPs were associated with allergic disease at a level of genome-wide suggestive significance (p<1.0×10-5) in the Korean population: rs7275360, located in neural cell adhesion molecule 2; rs698195; and rs3750552, located in family with sequence similarity 189, member A2. These polymorphisms were on chromosomes 21q21.1, 7q31.1, and 9q21.12, respectively.

CONCLUSION

We identified 3 novel SNPs significantly associated with allergic diseases in the Korean population. Further research is required to confirm the association between these novel SNPs and allergic disease in the Korean population and in other ethnicities.

Comorbidities in childhood atopic dermatitis: A population-based study

BACKGROUND

Atopic dermatitis (AD) is a chronic inflammatory skin disease that is associated with allergic comorbidities. However, studies examining comorbidities in childhood AD are incomplete, which may contribute to suboptimal care.

OBJECTIVE

The objective was to compare the risk of developing different allergic and non-allergic comorbidities among children with AD to that of a matched non-AD reference cohort in Sweden.

METHODS

This was a nationwide population-based cohort study using longitudinal data from primary and specialist care registers. Patients with AD were identified by confirmed diagnosis in primary or specialist care. The non-AD reference cohort was randomly drawn from the general population and matched 1:1 with the AD patients. The risk of developing the following conditions was evaluated: hypersensitivity and allergic disorders, neurological disorders, psychiatric disorders, infections, immunological and inflammatory disorders, Type 1 diabetes (T1D), endocrine and metabolic disorders, skeletal disorders, ocular disorders and malignancies.

RESULTS

This study included 165,145 patients with AD (mild-to-moderate [n = 126,681] and severe [n = 38,464]) and an equally sized reference cohort. Patients with AD displayed a higher risk of developing comorbid conditions for all investigated categories, except for T1D and skeletal disorders, compared with the reference cohort. The highest risk compared with the reference cohort was observed for hypersensitivity and allergic disorders (hazard ratio [HR]: 3.87), followed by malignancies (HR: 2.53) and immunological and inflammatory disorders (HR: 2.36). Patients with AD also had higher risk of developing multiple comorbidities (≥2). The risk of comorbidity onset increased alongside AD severity and patients with active AD were associated with increased risk of comorbidity onset compared with patients in remission.

CONCLUSIONS

The clinical burden of AD is substantial for children with AD and patients are at an increased risk of developing several comorbid conditions extending beyond the atopic march. Our results also showed a positive association between worsening severity of AD and an increased risk of comorbidity onset.

European and multi-ancestry genome-wide association meta-analysis of atopic dermatitis highlights importance of systemic immune regulation

Atopic dermatitis (AD) is a common inflammatory skin condition and prior genome-wide association studies (GWAS) have identified 71 associated loci. In the current study we conducted the largest AD GWAS to date (discovery N = 1,086,394, replication N = 3,604,027), combining previously reported cohorts with additional available data. We identified 81 loci (29 novel) in the European-only analysis (which all replicated in a separate European analysis) and 10 additional loci in the multi-ancestry analysis (3 novel). Eight variants from the multi-ancestry analysis replicated in at least one of the populations tested (European, Latino or African), while two may be specific to individuals of Japanese ancestry. AD loci showed enrichment for DNAse I hypersensitivity and eQTL associations in blood. At each locus we prioritised candidate genes by integrating multi-omic data. The implicated genes are predominantly in immune pathways of relevance to atopic inflammation and some offer drug repurposing opportunities.

Skin Colonization with S. aureus Can Lead to Increased NLRP1 Inflammasome Activation in Patients with Atopic Dermatitis

The role of NLRP1 inflammasome activation and subsequent production of IL-1 family cytokines in the development of atopic dermatitis (AD) is not clearly understood. Staphylococcus aureus is known to be associated with increased mRNA levels of IL1 family cytokines in the skin and more severe AD. In this study, the altered expression of IL-1 family cytokines and inflammasome-related genes was confirmed, and a positive relationship between mRNA levels of inflammasome sensor NLRP1 and IL1B or IL18 was determined. Enhanced expression of the NLRP1 and PYCARD proteins and increased caspase-1 activity were detected in the skin of patients with AD. The genetic association of IL18R1 and IL18RAP with AD was confirmed, and the involvement of various immune cell types was predicted using published GWAS and expression quantitative trait loci datasets. In keratinocytes, the inoculation with S. aureus led to the increased secretion of IL-1β and IL-18, whereas small interfering RNA silencing of NLRP1 inhibited the production of these cytokines. Our results suggest that skin colonization with S. aureus may cause the activation of the NLRP1 inflammasome in keratinocytes, which leads to the secretion of IL-1β and IL-18 and thereby may contribute to the pathogenesis of AD, particularly in the presence of genetic variations in the IL-18 pathway.

Atopic Dermatitis: Disease Features, Therapeutic Options, and a Multidisciplinary Approach

The latest findings regarding AD pathogenesis point to an impaired function of the epidermal barrier, changed immune response, colonization of the skin by microorganisms, and certain psychological factors among other causes/triggers. The inflammatory response of AD patients is mainly associated with the activation of T cells (Th2 cells predominate), dendritic cells, macrophages, keratinocytes, mast cells, and eosinophils. Therapy usually involves medical evaluations and adequate management including treatment of concomitant diseases (e.g., allergies and infections), patient education and nursing care, psychological support, and nutritional consultations, which are organized through specific programs and structured educational groups. Systemic AD therapy includes conventional systemic treatment (cyclosporine, methotrexate, azathioprine) and new, specific drugs, interleukin inhibitors (e.g., dupilumab) and JAK inhibitors (baricitinib, abrocitinib, upadacitinib, etc.). Since many AD patients are affected by various psychological factors and comorbidities, they should be assessed and managed through a multidisciplinary approach, involving different professions (psychologists, ear-nose-throat specialists, pulmonologists, allergologists, immunologists, nutritionists, pediatricians, gastroenterologists, psychiatrists (when necessary), and others). A multidisciplinary approach provides better coping strategies and improves control over the disease, patient adherence to therapy, and quality of life. It also has a positive influence on family quality of life while at the same time making more efficient use of dermatology healthcare resources, reducing the economic burden on both patients and society.

Overview of Atopic Dermatitis in Different Ethnic Groups

Atopic dermatitis (AD) is a common chronic inflammatory skin disease with a high prevalence worldwide, including countries from Asia, Africa, and Latin America, and in different ethnic groups. In recent years, more attention has been placed on the heterogeneity of AD associated with multiple factors, including a patient's ethnic background, resulting in an increasing body of clinical, genetic, epidemiologic, and immune-phenotypic evidence that delineates differences in AD among racial groups. Filaggrin (FLG) mutations, the strongest genetic risk factor for the development of AD, are detected in up to 50% of European and 27% of Asian AD patients, but very rarely in Africans. Th2 hyperactivation is a common attribute of all ethnic groups, though the Asian endotype of AD is also characterized by an increased Th17-mediated signal, whereas African Americans show a strong Th2/Th22 signature and an absence of Th1/Th17 skewing. In addition, the ethnic heterogeneity of AD may hold important therapeutic implications as a patient's genetic predisposition may affect treatment response and, thereby, a tailored strategy that better targets the dominant immunologic pathways in each ethnic subgroup may be envisaged. Nevertheless, white patients with AD represent the largest ethnicity enrolled and tested in clinical trials and the most treated in a real-world setting, limiting investigations about safety and efficacy across different ethnicities. The purpose of this review is to describe the heterogeneity in the pathophysiology of AD across ethnicities and its potential therapeutic implications.

New insights from genetic studies of eczema

Genome-wide association studies (GWAS) provided fundamental insight into the genetic determinants of complex allergic diseases. For eczema, 58 susceptibility loci were reported. Protein-changing variants were associated with eczema at genome-wide significance at 12 loci. The majority of risk variants were, however, located in non-coding, regulatory regions of the genome. Prioritized target genes were enriched in pathways of the immune response and of epithelial barrier function. Interestingly, a large overlap in the genetic architecture underlying different allergic diseases was identified pointing to common pathomechanisms for eczema, asthma, hay fever, and food allergy. Here, we review the most recent findings from GWAS for eczema including the role of rare variants and genetic heterogeneity in ethnically diverse populations. In addition, we provide an overview of genes underlying Mendelian disorders featuring eczematous skin inflammation.

GENECI: A novel evolutionary machine learning consensus-based approach for the inference of gene regulatory networks

Gene regulatory networks define the interactions between DNA products and other substances in cells. Increasing knowledge of these networks improves the level of detail with which the processes that trigger different diseases are described and fosters the development of new therapeutic targets. These networks are usually represented by graphs, and the primary sources for their correct construction are usually time series from differential expression data. The inference of networks from this data type has been approached differently in the literature. Mostly, computational learning techniques have been implemented, which have finally shown some specialization in specific datasets. For this reason, the need arises to create new and more robust strategies for reaching a consensus based on previous results to gain a particular capacity for generalization. This paper presents GENECI (GEne NEtwork Consensus Inference), an evolutionary machine learning approach that acts as an organizer for constructing ensembles to process the results of the main inference techniques reported in the literature and to optimize the consensus network derived from them, according to their confidence levels and topological characteristics. After its design, the proposal was confronted with datasets collected from academic benchmarks (DREAM challenges and IRMA network) to quantify its accuracy. Subsequently, it was applied to a real-world biological network of melanoma patients whose results could be contrasted with medical research collected in the literature. Finally, it has been proved that its ability to optimize the consensus of several networks leads to outstanding robustness and accuracy, gaining a certain generalization capacity after facing the inference of multiple datasets. The source code is hosted in a public repository at GitHub under MIT license: https://github.com/AdrianSeguraOrtiz/GENECI. Moreover, to facilitate its installation and use, the software associated with this implementation has been encapsulated in a python package available at PyPI: https://pypi.org/project/geneci/.

Significant Association between Obsessive-Compulsive Disorder and Atopic Dermatitis - a Retrospective Population-Based Case-Control Study

INTRODUCTION

Atopic dermatitis (AD) is a global health problem. There are no data on the association of AD with obsessive-compulsive disorder (OCD).

OBJECTIVES

This study aimed to map a wide spectrum of different diseases among patients with atopic dermatitis compared to healthy controls in the Region of Jönköping County, Sweden with special focus on OCD.

METHODS

We conducted a retrospective case control study from January 1^st 2013 until December 31^st 2021 using an electronic medical records database covering the entire population of the County of Jönköping. ICD-10 codes were used to identify patients with AD. Individuals without AD served as controls. A total number of 398,874 citizens under the age of 90 was included in this study and among these 2,946 individuals were diagnosed with AD. Regression analysis was performed to describe the risk for comorbidities in patients with AD compared to controls, adjusted for age and gender.

RESULTS

We found an association between obsessive-compulsive disorder (OCD) in patients with AD (adjusted odd ratio 2.0, 95% confidence interval 1.5-2.7, p<0.001). Other results are in the line with other studies.

CONCLUSION

Pointing to previous studies, the cause of AD and OCD share several gene-environmental mechanisms and this association should be further studied on larger populations. The results of the present study underline the need for dermatologists to be aware of OCD and to screen for this condition in AD patients because early diagnosis and treatment may improve outcome.

The Impact of Psoriasis and Atopic Dermatitis on Quality of Life: A Literature Research on Biomarkers

Psoriasis (PSO) and Atopic dermatitis (AD) are common inflammatory skin diseases that affect people of all ages globally. They negatively impact the quality of life (QoL) of patients in health-related aspects such as physical, psychological and mental functioning. Here, we conducted a review of studies relating to candidate biomarkers and indicators associated with QoL impairment in PSO and AD. Data research was performed using PUBMED and SCOPUS databases from inception to September 2022. Most of the included studies reported genomic or proteomic biomarkers associated with disease activity and QoL outcomes. Sociodemographic, clinical and therapeutic factors have also been implicated in deterioration of life quality in these patients. The inclusion of clinical characteristics, QoL impairment and co-diagnosis should be considered in drug development programs, since processing biomarkers based on an increased number of features in addition to drug class and disease will intensify the value of the biomarker itself, thereby maximizing the future clinical utility as a stratification tool.

Break on through: The role of innate immunity and barrier defence in atopic dermatitis and psoriasis

The human skin can be affected by a multitude of diseases including inflammatory conditions such as atopic dermatitis and psoriasis. Here, we describe how skin barrier integrity and immunity become dysregulated during these two most common inflammatory skin conditions. We summarise recent advances made in the field of the skin innate immune system and its interaction with adaptive immunity. We review gene variants associated with atopic dermatitis and psoriasis that affect innate immune mechanisms and skin barrier integrity. Finally, we discuss how current and future therapies may affect innate immune responses and skin barrier integrity in a generalized or more targeted approach in order to ameliorate disease in patients.

Epigenetic and transcriptional dysregulation in CD4+ T cells in patients with atopic dermatitis

Atopic dermatitis (AD) is one of the most common skin disorders among children. Disease etiology involves genetic and environmental factors, with 29 independent AD risk loci enriched for risk allele-dependent gene expression in the skin and CD4+ T cell compartments. We investigated the potential epigenetic mechanisms responsible for the genetic susceptibility of CD4+ T cells. To understand the differences in gene regulatory activity in peripheral blood T cells in AD, we measured chromatin accessibility (an assay based on transposase-accessible chromatin sequencing, ATAC-seq), nuclear factor kappa B subunit 1 (NFKB1) binding (chromatin immunoprecipitation with sequencing, ChIP-seq), and gene expression levels (RNA-seq) in stimulated CD4+ T cells from subjects with active moderate-to-severe AD, as well as in age-matched non-allergic controls. Open chromatin regions in stimulated CD4+ T cells were highly enriched for AD genetic risk variants, with almost half of the AD risk loci overlapping AD-dependent ATAC-seq peaks. AD-specific open chromatin regions were strongly enriched for NF-κB DNA-binding motifs. ChIP-seq identified hundreds of NFKB1-occupied genomic loci that were AD- or control-specific. As expected, the AD-specific ChIP-seq peaks were strongly enriched for NF-κB DNA-binding motifs. Surprisingly, control-specific NFKB1 ChIP-seq peaks were not enriched for NFKB1 motifs, but instead contained motifs for other classes of human transcription factors, suggesting a mechanism involving altered indirect NFKB1 binding. Using DNA sequencing data, we identified 63 instances of altered genotype-dependent chromatin accessibility at 36 AD risk variant loci (30% of AD risk loci) that might lead to genotype-dependent gene expression. Based on these findings, we propose that CD4+ T cells respond to stimulation in an AD-specific manner, resulting in disease- and genotype-dependent chromatin accessibility alterations involving NFKB1 binding.

Atopic dermatitis and risk of autoimmune conditions: Population-based cohort study

BACKGROUND

Atopic dermatitis (AD) is associated with immune dysregulation, but epidemiologic data on the pattern of autoimmune comorbidity in people with AD are limited.

OBJECTIVE

We sought to determine the risk of autoimmune conditions in people newly diagnosed with AD.

METHODS

Retrospective cohort analysis (January 2009 to December 2018), using the UK-based Oxford-Royal College of General Practitioners Research and Surveillance Centre primary care database. We compared baseline prevalence and incidence after diagnosis of autoimmune conditions in 173,709 children and adults with new-onset AD and 694,836 age-, sex-, and general practitioner practice-matched controls. Outcomes were a composite of any autoimmune condition (Crohn disease, ulcerative colitis, celiac disease, pernicious anemia, type 1 diabetes, autoimmune hypothyroidism, Graves disease, psoriatic arthritis, rheumatoid arthritis, ankylosing spondylitis, systemic lupus erythematosus, Sjögren syndrome, vitiligo, alopecia areata, and multiple sclerosis) and each individual autoimmune condition.

RESULTS

Preexisting autoimmune conditions were more common in people diagnosed with AD compared to controls (composite 5.8% vs 4.3%). Excluding people with preexisting autoimmune disease, there was an association between AD and incidence of new-onset autoimmune disease (composite adjusted hazard ratio [aHR] 1.28; 95% confidence interval [CI] 1.23-1.34). Risk was highest for more severe AD (aHR 1.99; 95% CI 1.77-2.23) than moderate AD (aHR 1.33; 95% CI 1.19-1.49) or mild AD (aHR 1.22; 95% CI 1.16-1.28). People with AD were at significantly increased risk of developing psoriatic arthritis, Sjögren syndrome, Crohn disease, vitiligo, alopecia areata, pernicious anemia, ulcerative colitis, rheumatoid arthritis, and hypothyroidism (aHR range 1.17-2.06), but not other autoimmune conditions.

CONCLUSION

People with AD have an increased risk of multiple autoimmune conditions, especially those with more severe AD.

Polymorphisms of the filaggrin gene are associated with atopic dermatitis in the Caucasian population of Central Russia

Association of the filaggrin (FLG) gene with atopic dermatitis (AD) in Caucasians from Central Russia was studied in the sample of 700 patients and 612 controls. In total ten SNPs of the gene (rs61816761, rs12130219, rs77199844, rs558269137, rs4363385, rs12144049, rs471144, rs6661961, rs10888499, rs3126085), their haplotypes and interlocus interactions were analyzed using logistic regression. The functional effects of the AD risk candidate loci and their proxies (136 SNPs) were evaluated by in silico analysis. All analyzed SNPs were associated with AD: two SNPs (rs3126085 and rs12144049) manifested the independent association, nine SNPs were associated within 30 haplotypes, and seven SNPs showed interlocus interaction effects within ten most significant epistatic models. Alleles A rs3126085 and C rs12144049 were associated with a higher risk of AD according to the allelic (ORs being 1.75, p_perm = 0.002 and 1.45, p_perm = 0.011 respectively), additive (ORs being 1.69, p_perm = 0.004 and 1.47, p_perm = 0.011 respectively) and dominant (ORs being 1.79, p_perm = 0.004 and 1.63, p_perm = 0.005 respectively) genetic models. Three haplotypes, GT[rs3126085-rs12144049] (OR = 0.60), GGT[rs61816761-rs3126085-rs12144049] (OR = 0.59), and AWGGT[rs12130219-rs558269137-rs61816761-rs3126085-rs12144049] (OR = 0.63) demonstrated the protective effect (p_perm = 0.001). The in silico analysis suggested that the AD risk variants and their proxies apparently produce various effects on 38 genes in various tissue/organs (including 20 genes in the skin). The biological process enrichment analyses suggest that the target AD candidate genes influence the formation of the cornified envelope, keratinization and cornification, and more than twenty other pathways related to skin development, programmed cell death, and regulation of water loss via skin.

Comprehensive Phytochemical Profiling of Polyherbal Divya-Kayakalp-Vati and Divya-Kayakalp-Oil and Their Combined Efficacy in Mouse Model of Atopic Dermatitis-Like Inflammation Through Regulation of Cytokines

PURPOSE

Atopic dermatitis (AD) is a chronic inflammatory disease that varies in signs and symptoms in different individuals. General symptoms include dryness of the skin, itching, and development of red to brownish-gray patches. Divya-Kayakalp-Vati (DKV) and -Oil (DKO) are Indian polyherbal compositions prescribed for treating inflammatory skin diseases. In the present study, we evaluated the anti-inflammatory efficacy of DKV and DKO co-treatment (DKV-O) in ameliorating Oxazolone (OXA)-stimulated AD-like inflammation and pro-inflammatory cytokine release in a Swiss albino mouse model.

METHODS

Phytochemical profiling of the DKV and DKO were done using Liquid Chromatography-Mass Spectroscopy (LC-MS) QToF. Swiss albino mice were sensitized for 7 days and treated with OXA in their ear region. Stimulated and control animals were orally treated with DKV and topically with DKO. Anti-inflammatory efficacy of DKV-O was determined in OXA-treated animals through physiological, histopathological, and biochemical parameter analysis.

RESULTS

DKV and DKO formulations individually contained 39 and 59 phytochemicals, respectively. Many of the phytochemicals have been reported to have anti-inflammatory activities. In the OXA-sensitized Swiss albino mice, combined treatment with DKV-O, and separately with Dexamethasone (positive control) significantly reduced the OXA-stimulated ear edema, biopsy weight, and epidermal thickness. DKV-O further reduced OXA-stimulated induction of inflammatory lesions, neutrophil influx, and release of Interleukin (IL)-1β, IL-6, tumor necrosis factor-α, and myeloperoxidase.

CONCLUSION

Finally, DKV-O co-treatment showed good pharmacological effects in ameliorating AD-like inflammation through the modulation of inflammatory cell influx and release of soluble mediators. Therefore, DKV-O treatment can be used as a suitable polyherbal therapeutic against AD-like inflammatory diseases.

Rare variant analysis in eczema identifies exonic variants in DUSP1, NOTCH4 and SLC9A4

Previous genome-wide association studies revealed multiple common variants involved in eczema but the role of rare variants remains to be elucidated. Here, we investigate the role of rare variants in eczema susceptibility. We meta-analyze 21 study populations including 20,016 eczema cases and 380,433 controls. Rare variants are imputed with high accuracy using large population-based reference panels. We identify rare exonic variants in DUSP1, NOTCH4, and SLC9A4 to be associated with eczema. In DUSP1 and NOTCH4 missense variants are predicted to impact conserved functional domains. In addition, five novel common variants at SATB1-AS1/KCNH8, TRIB1/LINC00861, ZBTB1, TBX21/OSBPL7, and CSF2RB are discovered. While genes prioritized based on rare variants are significantly up-regulated in the skin, common variants point to immune cell function. Over 20% of the single nucleotide variant-based heritability is attributable to rare and low-frequency variants. The identified rare/low-frequency variants located in functional protein domains point to promising targets for novel therapeutic approaches to eczema.

Genetic studies of eczema to date have mostly explored common genetic variation. Here, the authors perform a large meta-analysis for common and rare variants and discover 8 loci associated with eczema. Over 20% of the heritability of the condition is attributable to rare variants.

Drug Repurposing for Atopic Dermatitis by Integration of Gene Networking and Genomic Information

Atopic Dermatitis (AD) is a chronic and relapsing skin disease. The medications for treating AD are still limited, most of them are topical corticosteroid creams or antibiotics. The current study attempted to discover potential AD treatments by integrating a gene network and genomic analytic approaches. Herein, the Single Nucleotide Polymorphism (SNPs) associated with AD were extracted from the GWAS catalog. We identified 70 AD-associated loci, and then 94 AD risk genes were found by extending to proximal SNPs based on r2 > 0.8 in Asian populations using HaploReg v4.1. Next, we prioritized the AD risk genes using in silico pipelines of bioinformatic analysis based on six functional annotations to identify biological AD risk genes. Finally, we expanded them according to the molecular interactions using the STRING database to find the drug target genes. Our analysis showed 27 biological AD risk genes, and they were mapped to 76 drug target genes. According to DrugBank and Therapeutic Target Database, 25 drug target genes overlapping with 53 drugs were identified. Importantly, dupilumab, which is approved for AD, was successfully identified in this bioinformatic analysis. Furthermore, ten drugs were found to be potentially useful for AD with clinical or preclinical evidence. In particular, we identified filgotinub and fedratinib, targeting gene JAK1, as potential drugs for AD. Furthermore, four monoclonal antibody drugs (lebrikizumab, tralokinumab, tocilizumab, and canakinumab) were successfully identified as promising for AD repurposing. In sum, the results showed the feasibility of gene networking and genomic information as a potential drug discovery resource.

A Common Variant at 11q23.3 Is Associated with Susceptibility to Atopic Dermatitis in the Han Chinese Population

Background: Genome-wide association studies (GWASs) have identified many genetic variants that are risk factors for numerous immune-mediated diseases. In particular, different immune-mediated diseases have been found to share the same susceptibility loci. Therefore, exploring the genetic overlap between atopic dermatitis (AD) and other immune-mediated diseases in more detail may help identify additional shared susceptibility loci among common immune-mediated diseases. Recent evidence suggests that the 11q23.3 locus is a susceptibility locus shared among multiple immune-mediated diseases. Objective: This study was designed to investigated whether SNPs at the chromosome 11q23.3 locus are associated with AD in the Han Chinese population. Methods: In total, 16 SNPs within the 11q23.3 locus were genotyped using TaqMan assays for 1,012 AD cases and 1,362 controls. From these SNPs, we selected rs638893 with an association values of p < 5 × 10^-2 for AD for further analysis in an independent replication study using the Sequenom MassARRAY system to genotype an additional (consisting of 1,288 cases and 1,380 controls). The combined analyses were performed in two stages using a meta-analytical method. Results: We identified a common variant at 11q23.3 (rs638893), that was significantly associated (p = 1.58 × 10^-3, OR = 1.22) with AD. The genotype-based association analysis revealed that the recessive model provided the best fit for rs638893. Conclusion: Our study identified a variant on chromosome 11q23.3 that likely confers susceptibility to AD, thereby advancing our understanding of the genetic basis of this disease.

Uniting biobank resources reveals novel genetic pathways modulating susceptibility for atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is a common chronic inflammatory skin disease with high heritability. Previous genome-wide association studies have identified several loci predisposing to AD. These findings explain approximately 30% of the variance in AD susceptibility, suggesting that further work is required to fully understand the genetic underpinnings.

OBJECTIVE

We sought to gain additional understanding of the genetic contribution to AD risk by using biobank resources.

METHODS

We completed a genome-wide meta-analysis of AD in 796,661 individuals (N_cases = 22,474) from the FinnGen study, the Estonian Biobank, and the UK Biobank. We further performed downstream in silico analyses to characterize the risk variants at the novel loci.

RESULTS

We report 30 loci associating with AD (P < 5 × 10^-8), 5 of which are novel. In 2 of the novel loci, we identified missense mutations with deleterious predictions in desmocollin 1 and serpin family B member 7, genes encoding proteins crucial to epidermal strength and integrity.

CONCLUSIONS

These findings elucidate novel genetic pathways involved in AD pathophysiology. The likely involvement of desmocollin 1 and serpin family B member 7 in AD pathogenesis may offer opportunities for the development of novel treatment strategies for AD in the future.

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.

So close, and yet so far away: The dichotomy of the specific immune response and inflammation in psoriasis and atopic dermatitis

Characterization of the complex interplay between cytokines, chemokines and microorganisms has led to a better understanding of the pathogenesis of both psoriasis and AD and resulted in new therapeutics targeting distinct immune responses. Psoriasis and AD share many characteristics: they are highly prevalent, chronic, cause primarily skin inflammation, but are associated with comorbidities, and come with a devastating quality of life due to itch and stigmatization. However, the pathogenesis of psoriasis and AD is opposing - psoriasis is dominated by a Th17 immune response that causes neutrophil migration, induction of innate immunity and exaggerated epithelial metabolism. Leading cytokines of this Th17 immune response are IL-17A and F, IL-22 and TNF-a. AD is characterized by Th2 immunity characterized by the signature cytokines IL-4 and IL-13 leading to an impaired epidermal barrier, dampened innate immunity and eosinophil migration. This review compares genetics, microbiome and T-cell infiltrate and resulting epithelial response in psoriasis and AD. Whilst the antagonistic course of psoriasis and AD is confirmed by response to specific biologics targeting the key cytokines of inflammation in psoriasis and AD, respectively, clinically overlapping phenotypes are challenging in our daily clinical practice. We conclude this review by summarizing what is known about these mixed phenotypes and how the identification of clinically relevant endotypes and molecular-driven decision-making is the next step in the field of dermato-immunology.

Eight novel susceptibility loci and putative causal variants in atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is the most common allergic disease in the world. While genetic components play critical roles in its pathophysiology, a large proportion of its genetic background is still unexplored.

OBJECTIVES

This study sought to illuminate the genetic associations with AD using genome-wide association study (GWAS) and its downstream analyses.

METHODS

This study conducted a GWAS for AD comprising 2,639 cases and 115,648 controls in the Japanese population, followed by a trans-ethnic meta-analysis with UK Biobank data and downstream analyses including partitioning heritability analysis by linkage disequilibrium score regression.

RESULTS

This study identified 17 significant susceptibility loci, among which 4 loci-AFF1, ITGB8, EHMT1, and EGR2-were novel in the Japanese GWAS. The trans-ethnic meta-analysis revealed 4 additional novel loci, namely-ZBTB38,LOC105755953/LOC101928272, TRAF3, andIQGAP1. This study found a missense variant (R243W) with a deleterious functional effect in NLRP10 and a variant altering expression of CCDC80 via enhancer expression as highly likely causal variants. These 2 regions were Asian-specific, and these population-specific associations could be explained by the frequency of causal variants. The gene-based test showed SMAD4 as an additional novel significant locus. Downstream analyses revealed substantial overlap of GWAS significant signals in enhancers of skin cells and immune cells, especially CD4 T cells. A highly shared polygenic architecture of AD between Europeans and Asians was also found.

CONCLUSIONS

This study identified Japanese-specific loci and novel significant loci shared by different populations. Two putative causal variants were illuminated in Japanese-specific loci. Trans-ethnic analyses revealed strong heritability enrichment in immune-related pathways, and relevant cell types shared among populations.

Immune-mediated diseases and risk of Crohn's disease or ulcerative colitis: a prospective cohort study

BACKGROUND

Although immune-mediated diseases (IMDs) including inflammatory bowel diseases (IBDs) are known to cluster, to what extent this is due to common environmental influences is unknown.

AIM

To examine the incidence of IBD in individuals with another IMD.

METHODS

We used data from the prospective Nurses' Health Study II cohort (1995-2017) to examine the effect of diagnoses of several common IMDs on subsequent risk of Crohn's disease (CD) or ulcerative colitis (UC) using Cox proportional hazards models, adjusting for detailed diet and lifestyle confounders.

RESULTS

We documented 132 cases of CD and 186 cases of UC over 2 016 163 person-years of follow-up (median age at IBD diagnosis 50 years). Compared to participants with no history of IMD, the HRs of CD for those with 1 and ≥ 2 IMDs were 2.57 (95% CI 1.77-3.74) and 2.74 (95% CI 1.36 to 5.49), respectively (P_trend  < 0.0001). This association was only modestly attenuated by adjustment for environmental risk factors (HR 2.35 and 2.46, respectively). The risk of UC was not increased, with multivariable-adjusted HRs of 1.22 (95% CI 0.85-1.76) and 1.33 (95% CI 0.67-2.65) for those with 1 and ≥ 2 IMDs, respectively, compared to those with none (P_trend 0.16) (P_{heterogeneity} comparing CD and UC 0.037). Asthma, atopic dermatitis, psoriasis and rosacea were individually associated with higher risk of CD (HR ranging from 2.15 to 3.39) but not UC.

CONCLUSIONS

Individuals with one or more IMDs are at an increased risk for CD but not UC.

Current Developments of Clinical Sequencing and the Clinical Utility of Polygenic Risk Scores in Inflammatory Diseases

In this mini-review, we highlight selected research by the Deutsche Forschungsgemeinschaft (DFG) Cluster of Excellence “Precision Medicine in Chronic Inflammation” focusing on clinical sequencing and the clinical utility of polygenic risk scores as well as its implication on precision medicine in the field of the inflammatory diseases inflammatory bowel disease, atopic dermatitis and coronary artery disease. Additionally, we highlight current developments and discuss challenges to be faced in the future. Exemplary, we point to residual challenges in detecting disease-relevant variants resulting from difficulties in the interpretation of candidate variants and their potential interactions. While polygenic risk scores represent promising tools for the stratification of patient groups, currently, polygenic risk scores are not accurate enough for clinical setting. Precision medicine, incorporating additional data from genomics, transcriptomics and proteomics experiments, may enable the identification of distinct disease pathogeneses. In the future, data-intensive biomedical innovation will hopefully lead to improved patient stratification for personalized medicine.

Global differences in atopic dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disorder, with a highly variable prevalence worldwide. Recent evidence, however, has shown an increase in prevalence in the Asia Pacific region. Nevertheless, most of the published literature has focused mainly on Western populations, and only few clinical trials have included subgroups of other ethnic populations. Reasons for the observed ethnic and geographical differences in AD are not well established. This calls into question the need for a better understanding of AD pathogenesis and inter-ethnic differences in clinical and immuno-phenotypes. These differences may reflect inherent variability in disease mechanisms between populations, which in turn may impact upon treatment responses such as biologics that are currently tailored mainly to a specific immuno-phenotype (T-helper type 2 dominant). In this article, we reviewed existing literature on the prevalence of AD globally, highlighting differences, if any, in the clinical and immuno-phenotypes of AD between different ethnicities. We discussed genetic and environmental factors that affect AD in different populations and therapeutic considerations. Our review highlights AD as a disease with ethnic-dependent clinical and immunological heterogeneity and calls for greater inclusion of ethnic diversity in future research in order to develop targeted treatments.

Single nucleotide variations in genes associated with innate immunity are enriched in Japanese adult cases of face and neck type atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is heterogenous in terms of phenotype as well as genetic and environmental factors, while its associated genetic factors and pathophysiology are not fully understood.

OBJECTIVE

We identify novel genetic factors enriched in a subgroup of AD patients with characteristic clinical features.

METHODS

We clinically subgrouped 18 AD patients who exhibited distinctive characteristic of persistent skin eruption areas on the face and neck from 92 Japanese adult AD patients and identified disease-associated genetic factors enriched within the subgroup. Targeted resequencing and subsequent genetic association analyses were used to identify novel enriched genetic variations in the subgroup compared with the other AD patients.

RESULTS

Targeted resequencing of 648 skin associated genes revealed an enrichment of 12 single nucleotide variations (SNVs) in patients with face and neck AD (n = 18) compared with the general Japanese population in the database. Subsequent allele frequency comparison between the face and neck AD and non - face and neck AD subgroups revealed enrichment of five SNVs. Multivariate analysis using genotype data revealed that three SNVs in theTLR1, TIRAP, and PSAPL1 genes, two of the three genes are involved in the Toll-like receptor pathway, were significantly enriched in patients with face and neck AD.

CONCLUSION

These findings revealed that the SNVs in genes associated with the innate immune pathway are enriched in a subgroup of AD. The combinational approach of clinical subgrouping and genotyping is valuable for detecting novel disease-associated genetic factors.

The Role of Genetics, the Environment, and Epigenetics in Atopic Dermatitis

Atopic Dermatitis (AD) is a common inflammatory disease with a genetic background. The prevalence of AD has been increasing in many countries. AD patients often have manifestations of pruritus, generalized skin dryness, and eczematous lesions. The pathogenesis of AD is complicated. The impaired skin barrier and immune imbalance play significant roles in the development of AD. Environmental factors such as allergens and pollutants are associated with the increasing prevalence. Many genetic and environmental factors induce a skin barrier deficiency, and this can lead to immune imbalance, which exacerbates the impaired skin barrier to form a vicious cycle (outside-inside-outside view). Genetic studies find many gene mutations and genetic variants, such as filaggrin mutations, which may directly induce the deficiency of the skin barrier and immune system. Epigenetic studies provide a connection between the relationship of an impaired skin barrier and immune and environmental factors, such as tobacco exposure, pollutants, microbes, and diet and nutrients. AD is a multigene disease, and thus there are many targets for regulation of expression of these genes which may contribute to the pathogenesis of AD. However, the epigenetic regulation of environmental factors in AD pathogenesis still needs to be further researched.

Predictive in silico binding algorithms reveal HLA specificities and autoallergen peptides associated with atopic dermatitis

Atopic dermatitis (AD) is a skin disease that results from a combination of skin barrier dysfunction and immune dysregulation. The immune dysregulation is often associated with IgE sensitivity. There is also evidence that autoallergens Hom s 1, 2, 3, and 4 play a role in AD; it is possible that patients with specific HLA subtypes are predisposed to autoreactivity due to increased presentation of autoallergen peptides. The goal of our study was to use in silico epitope prediction platforms as an approach to identify HLA subtypes that may preferentially bind autoallergen peptides and are thus candidates for further study. Considering the previously described association of DRB1 alleles with AD and progression of disease, emphasis was placed on DRB1. Certain DRB1 alleles (08:04, 11:01, and 11:04) were identified by both algorithms to bind a significant percent of the generated autoallergen peptides. Conversely, autoallergen core peptide sequences FRQLSHRFH and IRAKLRLQA (Hom s 1), IRKSKNILF (Hom s 2), FKWVPVTDS and MAAIEKVRK (Hom s 3), and FRYFATLKV (Hom s 4) were predicted to bind many DRB1 alleles and, thus, may play a role in the pathogenesis of AD. Our findings provide candidate DRB1 alleles and autoallergen epitopes that will guide future studies exploring the relationship between DRB1 subtype and autoreactivity in AD. A similar approach can be used for any antigen that has been associated with an IgE response and AD.