Association of HLA-DRB1 genetic variants with the persistence of atopic dermatitis

Asthma and atopic dermatitis as risk factors for rheumatoid arthritis: a bidirectional mendelian randomization study

BACKGROUND

Previous observational studies have shown an association between asthma, atopic dermatitis (AD) and rheumatoid arthritis (RA). However, the bidirectional cause-effect chain between asthma and AD and RA has not been proven yet.

METHODS

We performed bidirectional two-sample Mendelian randomization (TSMR) and selected single nucleotide polymorphisms (SNPs) associated with asthma, AD, and RA as instrumental variables. All of the SNPs were obtained from the latest genome-wide association study in Europeans. Inverse variance weighted (IVW) was the main method used in MR analysis. MR-Egger, weighted model, simple model, and weighted median were used for quality control. The robustness of the results was tested by sensitivity analysis.

RESULTS

Asthma was found to be the largest effect size for RA susceptibility using the IVW method (OR, 1.35;95%CI, 1.13-1.60; P, 0.001), followed by AD (OR, 1.10;95%CI, 1.02-1.19; P, 0.019). In contrast, there was no causal relationship between RA and asthma (IVW: P = 0.673) or AD (IVW: P = 0.342). No pleiotropy or heterogeneity was found in the sensitivity analysis.

CONCLUSION

Findings from this study showed a causal relationship between genetic susceptibility to asthma or AD and increased risk of RA, but do not support a causal relationship between genetic susceptibility to RA and asthma or AD.

A combination of HLA-DP α and β chain polymorphisms paired with a SNP in the DPB1 3' UTR region, denoting expression levels, are associated with atopic dermatitis

Introduction: Components of the immune response have previously been associated with the pathophysiology of atopic dermatitis (AD), specifically the Human Leukocyte Antigen (HLA) Class II region via genome-wide association studies, however the exact elements have not been identified. Methods: This study examines the genetic variation of HLA Class II genes using next generation sequencing (NGS) and evaluates the resultant amino acids, with particular attention on binding site residues, for associations with AD. The Genetics of AD cohort was used to evaluate HLA Class II allelic variation on 464 subjects with AD and 384 controls. Results: Statistically significant associations with HLA-DP α and β alleles and specific amino acids were found, some conferring susceptibility to AD and others with a protective effect. Evaluation of polymorphic residues in DP binding pockets revealed the critical role of P1 and P6 (P1: α31M + (β84G or β84V) [protection]; α31Q + β84D [susceptibility] and P6: α11A + β11G [protection]) and were replicated with a national cohort of children consisting of 424 AD subjects. Independently, AD susceptibility-associated residues were associated with the G polymorphism of SNP rs9277534 in the 3' UTR of the HLA-DPB1 gene, denoting higher expression of these HLA-DP alleles, while protection-associated residues were associated with the A polymorphism, denoting lower expression. Discussion: These findings lay the foundation for evaluating non-self-antigens suspected to be associated with AD as they potentially interact with particular HLA Class II subcomponents, forming a complex involved in the pathophysiology of AD. It is possible that a combination of structural HLA-DP components and levels of expression of these components contribute to AD pathophysiology.

KIR Allelic Variation and the Remission of Atopic Dermatitis Over Time

Atopic dermatitis (AD) is a common chronic skin disease. Although generally thought to be a disease of T-cell dysregulation, recent studies have suggested that immune dysregulation of NK cells is also important. Killer cell Ig-like receptors (KIRs) are involved with NK cell regulation. The Pediatric Eczema Elective Registry is a U.S. nationwide longitudinal cohort with up to 10 y of follow-up in which 655 children had DNA available for full allelic KIR sequencing. Every 6 mo, AD activity was reported by Pediatric Eczema Elective Registry children. Using generalized estimating equations, we evaluated the association of KIR allelic variation in concert with known HLA binding ligands and whether the child reported AD in "remission" (no skin lesions and not using AD medication). KIR2DS4*001:01 (odds ratio 0.53, 95% CI [0.32, 0.88]) and KIR2DL4*001:02 (0.54, [0.33, 0.89]) in the presence of C*04:01 had the largest effect on decreasing the likelihood of AD remission. The haplotype KIR 2DL4*001:02 ∼ 2DS4*001:01 ∼ 3DL2*002:01 (0.77, [0.60, 0.99]) was also associated with a decreased likelihood of AD remission. Our findings add to the general body of evidence of a growing literature on the importance of NK cells with respect to the immunopathogenesis and natural history of AD.

Human leukocyte antigen system associations in Malassezia-related skin diseases

BACKGROUND

The human leukocyte antigen system (HLA) is divided into two classes involved in antigen presentation: class I presenting intracellular antigens and class II presenting extracellular antigens. While susceptibility to infections is correlated with the HLA system, data on associations between HLA genotypes and Malassezia-related skin diseases (MRSD) are lacking. Thus, the objective of this study was to investigate associations between HLA alleles and MRSD.

MATERIALS AND METHODS

Participants in The Danish Blood Donor Study (2010-2018) provided questionnaire data on life style, anthropometric measures, and registry data on filled prescriptions. Genotyping was done using Illumina Infinium Global Screening Array, and HLA alleles were imputed using the HIBAG algorithm. Cases and controls were defined using filled prescriptions on topical ketoconazole 2% as a proxy of MRSD. Logistic regressions assessed associations between HLA alleles and MRSD adjusted for confounders and Bonferroni corrected for multiple tests.

RESULTS

A total of 9455 participants were considered MRSD cases and 24,144 participants as controls. We identified four risk alleles B*57:01, OR 1.19 (95% CI: 1.09-1.31), C*01:02, OR 1.19 (95% CI: 1.08-1.32), C*06:02, OR 1.14 (95% CI: 1.08-1.22), and DRB1*01:01, OR 1.10 (95% CI: 1.04-1.17), and two protective alleles, DQB1*02:01, OR 0.89 (95% CI: 0.85-0.94), and DRB1*03:01, OR 0.89 (95% CI: 0.85-0.94).

CONCLUSION

Five novel associations between HLA alleles and MRSD were identified in our cohort, and one previous association was confirmed. Future studies should assess the correlation between Malassezia antigens and antigen-binding properties of the associated HLA alleles.

Atopy as Immune Dysregulation: Offender Genes and Targets

Allergic diseases are a heterogeneous group of disorders resulting from exaggerated type 2 inflammation. Although typically viewed as polygenic multifactorial disorders caused by the interaction of several genes with the environment, we have come to appreciate that allergic diseases can also be caused by monogenic variants affecting the immune system and the skin epithelial barrier. Through a myriad of genetic association studies and high-throughput sequencing tools, many monogenic and polygenic culprits of allergic diseases have been described. Identifying the genetic causes of atopy has shaped our understanding of how these conditions occur and how they may be treated and even prevented. Precision diagnostic tools and therapies that address the specific molecular pathways implicated in allergic inflammation provide exciting opportunities to improve our care for patients across the field of allergy and immunology. Here, we highlight offender genes implicated in polygenic and monogenic allergic diseases and list targeted therapeutic approaches that address these disrupted pathways.

Atopic Dermatitis is a Risk Factor for Rheumatoid Arthritis: A Systematic Review and Meta-Analysis

BACKGROUND

It is still unclear whether patients with atopic dermatitis (AD) have an increased risk of developing rheumatoid arthritis (RA).

OBJECTIVE

We aimed to investigate the association between AD and risk of RA using systematic review and meta-analysis.

METHODS

We searched Medline and EMBASE up to April 2021 using search strategy, including terms for "atopic dermatitis" and "rheumatoid arthritis." Eligible cohort study must compare the incidence of RA between patients with AD and comparators without AD. Eligible case-control study must recruit cases with RA and controls without RA. Then, the study must compare the prevalence of AD between the groups. Point estimates with standard errors from each study were combined using the generic inverse variance method.

RESULTS

The meta-analysis found that AD patients had a significantly higher risk of incident RA than individuals without AD with a pooled odds ratio (OR) of 1.30 (95% confidence interval [CI], 1.17-1.44; I2, 48%). Subgroup analysis revealed a significantly higher risk of RA in cohort study subgroup (pooled OR, 1.37; 95% CI, 1.25-1.50; I2, 63%) but not case-control study subgroup (pooled OR, 0.99; 95% CI, 0.77-1.28; I2, 10%).

CONCLUSIONS

This study found a significantly higher risk of incident RA among AD patients.

Association of atopic dermatitis with an increased risk of systemic lupus erythematosus: A systematic review and meta-analysis

Context:

Previous studies on the association between atopic dermatitis (AD) and systemic lupus erythematosus (SLE) have yielded inconsistent results.

Aims:

To investigate the relationship between atopic dermatitis and systemic lupus erythematosus.

Settings and Design:

Systematic review and meta-analysis.

Materials and Methods:

A systematic review was conducted on EMBASE and MEDLINE databases from inception to March 2020 using a search strategy that consisted of terms related to AD and SLE. Eligible study must be either cohort or case-control study. For cohort studies, they must include patients with AD and comparators without AD, then follow them for incident SLE. For case-control studies, they must include cases with SLE and controls without SLE and examine their prior history of AD.

Statistical Analysis Used:

Meta-analysis of the studies was performed using a random-effect, generic inverse variance method to combine effect estimate and standard error. Funnel plot was used to assess publication bias.

Results:

A total of 21,486 articles were retrieved. After two rounds of review by three investigators, six case-control studies were qualified for the meta-analysis. The case-control study meta-analysis found a significantly increased odds of SLE among patients with AD with the pooled odds ratio of 1.46 (95% CI, 1.05–2.04).

Conclusions:

A significant association between AD and increased odds of SLE was observed by this systematic review and meta-analysis.

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.

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

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

A deep dive into UV-based phototherapy: Mechanisms of action and emerging molecular targets in inflammation and cancer

UV-based phototherapy (including psoralen plus UVA (PUVA), UVB and UVA1) has a long, successful history in the management of numerous cutaneous disorders. Photoresponsive diseases are etiologically diverse, but most involve disturbances in local (and occasionally systemic) inflammatory cells and/or abnormalities in keratinocytes that trigger inflammation. UV-based phototherapy works by regulating the inflammatory component and inducing apoptosis of pathogenic cells. This results in a fascinating and complex network of simultaneous events-immediate transcriptional changes in keratinocytes, immune cells, and pigment cells; the emergence of apoptotic bodies; and the trafficking of antigen-presenting cells in skin-that quickly transform the microenvironment of UV-exposed skin. Molecular elements in this system of UV recognition and response include chromophores, metabolic byproducts, innate immune receptors, neurotransmitters and mediators such as chemokines and cytokines, antimicrobial peptides, and platelet activating factor (PAF) and PAF-like molecules that simultaneously shape the immunomodulatory effects of UV and their interplay with the microbiota of the skin and beyond. Phototherapy's key effects-proapoptotic, immunomodulatory, antipruritic, antifibrotic, propigmentary, and pro-prebiotic-promote clinical improvement in various skin diseases such as psoriasis, atopic dermatitis (AD), graft-versus-host disease (GvHD), vitiligo, scleroderma, and cutaneous T-cell lymphoma (CTCL) as well as prevention of polymorphic light eruption (PLE). As understanding of phototherapy improves, new therapies (UV- and non-UV-based) are being developed that will modify regulatory T-cells (Treg), interact with (resident) memory T-cells and /or utilize agonists and antagonists as well as antibodies targeting soluble molecules such as cytokines and chemokines, transcription factors, and a variety of membrane-associated receptors.

Prenatal PM2.5 exposure and vitamin D-associated early persistent atopic dermatitis via placental methylation

BACKGROUND

The effects of prenatal particulate matter with an aerodynamic diameter ranging from 0.1 μm to 2.5 μm (PM_2.5) and vitamin D on atopic dermatitis (AD) phenotypes have not been evaluated. DNA methylation and cord blood (CB) vitamin D could represent a plausible link between prenatal PM_2.5 exposure and AD in an offspring.

OBJECTIVE

To determine the critical windows of prenatal PM_2.5 exposure on the AD phenotypes, if vitamin D modulated these effects, and if placental DNA methylation mediated these effects on AD in offspring.

METHODS

Mother-child pairs were enrolled from the birth cohort of the Cohort for Childhood Origin of Asthma and allergic diseases (COCOA) study. PM_2.5 was estimated by land-use regression models, and CB vitamin D was measured by chemiluminescence immunoassay. AD was identified by the parental report of a physician's diagnosis. We defined the following 4 AD phenotypes according to onset age (by the age of 2 years) and persistence (by the age of 3 years): early-onset transient and persistent, late onset, and never. Logistic regression analysis and Bayesian distributed lag interaction model were used. DNA methylation microarray was analyzed using an Infinium Human Methylation EPIC BeadChip (Illumina, San Diego, California) in placenta.

RESULTS

PM_2.5 exposure during the first trimester of pregnancy, especially during 6 to 7 weeks of gestation, was associated with early-onset persistent AD. This effect increased in children with low CB vitamin D, especially in those with PM_2.5 exposure during 3 to 7 weeks of gestation. AHRR (cg16371648), DPP10 (cg19211931), and HLADRB1 (cg10632894) were hypomethylated in children with AD with high PM_2.5 and low CB vitamin D.

CONCLUSION

Higher PM_2.5 during the first trimester of pregnancy and low CB vitamin D affected early-onset persistent AD, and the most sensitive window was 6 to 7 weeks of gestation. Placental DNA methylation mediated this effect.

Which Way Do We Go? Complex Interactions in Atopic Dermatitis Pathogenesis

Atopic dermatitis (AD) is a common, chronic, inflammatory skin condition characterized by recurrent and pruritic skin eruptions. Multiple factors contribute to the pathogenesis of AD, including skin barrier dysfunction, microbial dysbiosis, and immune dysregulation. Interactions among these factors form a complex, multidirectional network that can reinforce atopic skin disease but can also be ameliorated by targeted therapies. This review summarizes the complex interactions among contributing factors in AD and the implications on disease development and therapeutic interventions.

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.

Association of FLG single nucleotide variations with clinical phenotypes of atopic dermatitis

Background

FLG encodes a large protein called profilaggrin, which plays a key role in maintaining an effective skin barrier against the environment. In this study, we identified FLG single nucleotide variations (FLG-SNVs) and evaluated the association of FLG-SNVs with clinical phenotypes including atopic dermatitis (AD)-associated minor clinical features, presence of specific allergic sensitization, and serum parameters.

Methods

Eighty-one Korean patients with AD were enrolled. AD-associated minor clinical features as well as allergic rhinitis and asthma were diagnosed by specialists. FLG-SNVs were identified by Sanger sequencing of entire exons through long-range PCR. Allergic sensitization to a specific allergen was evaluated by multiple allergen simultaneous test. Serologic parameters such as serum eosinophil cationic protein (ECP) and eosinophil derived neurotoxin (EDN) were measured.

Results

A total of seventy-three SNVs and 4 LOF mutations were successfully genotyped. rs71626704 and rs76413899 were significantly associated with a history of asthma and cheilitis (P = 0.002 and P = 0.033, respectively), however, the associations were not found statistically significant after adjustment by multiple comparisons. In addition, we detected haplotype blocks which were correlated with non-specific hand or foot dermatitis and scalp scale. We identified FLG-SNVs which were associated with sensitization to environmental allergens; rs62623409 and rs71625199 (P = 0.038 and P = 0.008, respectively). Patients with FLG P478S TT and history of allergic rhinitis showed a higher EDN level, and among those patients, the ones with asthma showed a higher ECP level.

Conclusion

This study revealed the association of FLG-SNVs with AD-associated minor clinical features. We firstly identified rs71625199 which was associated with higher environmental allergic sensitization. We also suggest that FLG P478S is a kind of disease modifier which affects serologic parameters such as EDN and ECP.