No abstract

Summary Background Loss‐of‐function mutations in the skin barrier gene filaggrin (FLG) increase the risk of atopic dermatitis (AD), but their role in skin barrier function, dry skin and eczema in infancy is unclear. Objectives To determine the role of FLG mutations in impaired skin barrier function, dry skin, eczema and AD at 3 months of age and throughout infancy. Methods FLG mutations were analysed in 1836 infants in the Scandinavian population‐based PreventADALL study. Transepidermal water loss (TEWL), dry skin, eczema and AD were assessed at 3, 6 and 12 months of age. Results FLG mutations were observed in 166 (9%) infants. At 3 months, carrying FLG mutations was not associated with impaired skin barrier function (TEWL > 11·3 g m−2 h−1) or dry skin, but was associated with eczema [odds ratio (OR) 2·89, 95% confidence interval (CI) 1·95–4·28; P < 0·001]. At 6 months, mutation carriers had significantly higher TEWL than nonmutation carriers [mean 9·68 (95% CI 8·69–10·68) vs. 8·24 (95% CI 7·97–8·15), P < 0·01], and at 3 and 6 months mutation carriers had an increased risk of dry skin on the trunk (OR 1·87, 95% CI 1·25–2·80; P = 0·002 and OR 2·44, 95% CI 1·51–3·95; P < 0·001) or extensor limb surfaces (OR 1·52, 95% CI 1·04–2·22; P = 0·028 and OR 1·74, 95% CI 1·17–2·57; P = 0·005). FLG mutations were associated with eczema and AD in infancy. Conclusions FLG mutations were not associated with impaired skin barrier function or dry skin in general at 3 months of age, but increased the risk for eczema, and for dry skin on the trunk and extensor limb surfaces at 3 and 6 months.

The major histocompatibility complex class II transactivator (CIITA) gene (16p13) has been reported to associate with susceptibility to multiple sclerosis, rheumatoid arthritis and myocardial infarction, recently also to celiac disease at genome-wide level. However, attempts to replicate association have been inconclusive. Previously, we have observed linkage to the CIITA region in Scandinavian type 1 diabetes (T1D) families. Here we analyze five Swedish T1D cohorts and a combined control material from previous studies of CIITA. We investigate how the genotype distribution within the CIITA gene varies depending on age, and the association to T1D. Unexpectedly, we find a significant difference in the genotype distribution for markers in CIITA (rs11074932, P ¼ 4 Â 10 À 5 and rs3087456, P ¼ 0.05) with respect to age, in the collected control material. This observation is replicated in an independent cohort material of about 2000 individuals (P ¼ 0.006, P ¼ 0.007). We also detect association to T1D for both markers, rs11074932 (P ¼ 0.004) and rs3087456 (P ¼ 0.001), after adjusting for age at sampling. The association remains independent of the adjacent T1D risk gene CLEC16A. Our results indicate an age-dependent variation in CIITA allele frequencies, a finding of relevance for the contrasting outcomes of previously published association studies.

Phototherapy with narrow‐band Ultraviolet B (nb‐UVB) is a major therapeutic option in atopic dermatitis (AD), yet knowledge of the early molecular responses to this treatment is lacking. The objective of this study was to map the early transcriptional changes in AD skin in response to nb‐UVB treatment. Adult patients (n = 16) with AD were included in the study and scored with validated scoring tools. AD skin was irradiated with local nb‐UVB on day 0, 2 and 4. Skin biopsies were taken before and after treatment (day 0 and 7) and analysed for genome‐wide modulation of transcription. When examining the early response after three local UVB treatments, gene expression analysis revealed 77 significantly modulated transcripts (30 down‐ and 47 upregulated). Among them were transcripts related to the inflammatory response, melanin synthesis, keratinization and epidermal structure. Interestingly, the pro‐inflammatory cytokine IL‐36γ was reduced after treatment, while the anti‐inflammatory cytokine IL‐37 increased after treatment with nb‐UVB. There was also a modulation of several other mediators involved in inflammation, among them defensins and S100 proteins. This is the first study of early transcriptomic changes in AD skin in response to nb‐UVB. We reveal robust modulation of a small group of inflammatory and anti‐inflammatory targets, including the IL‐1 family members IL36γ and IL‐37, which is evident before any detectable changes in skin morphology or immune cell infiltrates. These findings provide important clues to the molecular mechanisms behind the treatment response and shed light on new potential treatment targets.

Taken together, we demonstrate that tight junction genes and, in particular, CLDN1 rather than variants in FLG may be involved in the susceptibility of AD in the Ethiopian population.

BackgroundWe have previously performed a genome-wide linkage study in Scandinavian Type 1 diabetes (T1D) families. In the Swedish families, we detected suggestive linkage (LOD≤2.2) to the chromosome 5p13-q13 region. The aim of our study was to investigate the linked region in search for possible T1D susceptibility genes.Methodology/Principal FindingsMicrosatellites were genotyped in the Scandinavian families to fine-map the previously linked region. Further, SNPs were genotyped in Swedish and Danish families as well as Swedish sporadic cases. In the Swedish families we detected genome-wide significant linkage to the 5-hydroxytryptamine receptor 1A (HTR1A) gene (LOD 3.98, p<9.8×10−6). Markers tagging two separate genes; the ring finger protein 180 (RNF180) and HTR1A showed association to T1D in the Swedish and Danish families (p<0.002, p<0.001 respectively). The association was not confirmed in sporadic cases. Conditional analysis indicates that the primary association was to HTR1A. Quantitative PCR show that transcripts of both HTR1A and RNF180 are present in human islets of Langerhans. Moreover, immunohistochemical analysis confirmed the presence of the 5-HTR1A protein in isolated human islets of Langerhans as well as in sections of human pancreas.ConclusionsWe have identified and confirmed the association of both HTR1A and RFN180, two genes in high linkage disequilibrium (LD) to T1D in two separate family materials. As both HTR1A and RFN180 were expressed at the mRNA level and HTR1A as protein in human islets of Langerhans, we suggest that HTR1A may affect T1D susceptibility by modulating the initial autoimmune attack or either islet regeneration, insulin release, or both.

Background: Hundreds of variants associated with atopic dermatitis (AD) and psoriasis, 2 common inflammatory skin disorders, have previously been discovered through genomewide association studies (GWASs). The majority of these variants are in noncoding regions, and their target genes remain largely unclear. Objective: We sought to understand the effects of these noncoding variants on the development of AD and psoriasis by linking them to the genes that they regulate. Methods: We constructed genomic 3-dimensional maps of human keratinocytes during differentiation by using targeted chromosome conformation capture (Capture Hi-C) targeting more than 20,000 promoters and 214 GWAS variants and combined these data with transcriptome and epigenomic data sets. We validated our results with reporter assays, clustered regularly interspaced short palindromic repeats activation, and examination of patient gene expression from previous studies. Results: We identified 118 target genes of 82 AD and psoriasis GWAS variants. Differential expression of 58 of the 118 target genes (49%) occurred in either AD or psoriatic lesions, many of which were not previously linked to any skin disease. We highlighted the genes AFG1L, CLINT1, ADO, LINC00302, and RP1-140J1.1 and provided further evidence for their potential roles in AD and psoriasis. Conclusions: Our work focused on skin barrier pathology through investigation of the interaction profile of GWAS variants during keratinocyte differentiation. We have provided a catalogue of candidate genes that could modulate the risk of AD and psoriasis. Given that only 35% of the target genes are the gene nearest to the known GWAS variants, we expect that our work will contribute to the discovery of novel pathways involved in AD and psoriasis. (J Allergy Clin Immunol 2020;nnn:nnn-nnn.)

<b><i>Background:</i></b> The pathophysiology in atopic dermatitis (AD) is not fully understood, but immune dysfunction, skin barrier defects, and alterations of the skin microbiota are thought to play important roles. AD skin is frequently colonized with <i>Staphylococcus aureus</i> (<i>S. aureus</i>) and microbial diversity on lesional skin (LS) is reduced compared to on healthy skin. Treatment with narrow-band ultraviolet B (nb-UVB) leads to clinical improvement of the eczema and reduced abundance of <i>S. aureus</i>. However, in-depth knowledge of the temporal dynamics of the skin microbiota in AD in response to nb-UVB treatment is lacking and could provide important clues to decipher whether the microbial changes are primary drivers of the disease, or secondary to the inflammatory process. <b><i>Objectives:</i></b> To map the temporal shifts in the microbiota of the skin, nose, and throat in adult AD patients after nb-UVB treatment. <b><i>Methods:</i></b> Skin swabs were taken from lesional AD skin (<i>n</i> = 16) before and after 3 treatments of nb-UVB, and after 6–8 weeks of full-body treatment. We also obtained samples from non-lesional skin (NLS) and from the nose and throat. All samples were characterized by 16S rRNA gene sequencing. <b><i>Results:</i></b> We observed shifts towards higher diversity in the microbiota of lesional AD skin after 6–8 weeks of treatment, while the microbiota of NLS and of the nose/throat remained unchanged. After only 3 treatments with nb-UVB, there were no significant changes in the microbiota. <b><i>Conclusion:</i></b> Nb-UVB induces changes in the skin microbiota towards higher diversity, but the microbiota of the nose and throat are not altered.