Single-cell Transcriptomics Combined With Interstitial Fluid Proteomics Defines Cell Type-Specific Immune Regulation in Atopic Dermatitis
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ABSTRACT: Background: Atopic dermatitis (AD) is the most common chronic inflammatory skin disease, but its complex pathogenesis is only insufficiently understood, resulting in still limited treatment options. Objective: We sought to characterize AD on both transcriptomic and proteomic levels in humans. Methods: We used skin suction blistering, a painless and nonscarring procedure that can simultaneously sample skin cells and interstitial fluid. We then compared results with conventional biopsies. Results: Suction blistering captured epidermal and most immune cells equally well as biopsies, except for mast cells and nonmigratory CD163+ macrophages that were only present in biopsy isolates. Using single-cell RNA sequencing, we found comparable transcriptional profiles of key inflammatory pathways between blister and biopsy AD, but suction blistering was superior in cell-specific resolution for high-abundance transcripts (KRT1/KRT10, KRT16/KRT6A, S100A8/S100A9), which showed some background signals in biopsy isolates. Compared with healthy controls, we found characteristic upregulation of AD-typical cytokines such as IL13 and IL22 in Th2 and Th22 cells, respectively, but we also discovered these mediators in proliferating T cells and natural killer T cells, that also expressed the antimicrobial cytokine IL26. Overall, not T cells, but myeloid cells were most strongly enriched in AD, and we found dendritic cell (CLEC7A, amphiregulin/AREG, EREG) and macrophage products (CCL13) among the top upregulated proteins in AD blister fluid proteomic analyses. Conclusion: These data show that by using cutting-edge technology, suction blistering offers several advantages over conventional biopsies, including better transcriptomic resolution of skin cells, combined with proteomic information from interstitial fluid, unraveling novel inflammatory players that shape the cellular and proteomic microenvironment of AD.
Project description:Allergic and irritant contact dermatitis can be challenging to distinguish. We used single cell RNA sequencing (scRNA-seq) and insterstitial fluid proteomic analysis to compare suction blister biopsy skin samples from human volunteers with induced allergic and irritant contact dermatitis reactions.
Project description:Atopic dermatitis (AD) typically starts in infancy or early childhood, showing spontaneous remission in a subset of patients, while others develop lifelong disease. Despite an increased understanding of AD, factors guiding its natural course are only insufficiently elucidated. We thus performed suction blistering in skin of adult patients with stable, spontaneous remission from previous moderate-to-severe AD during childhood. Samples were compared to healthy controls without personal or familial history of atopy, and to chronic, active AD lesions. Skin cells and tissue fluid obtained were used for single-cell RNA sequencing and proteomic multiplex assays, respectively. We found overall cell composition and proteomic profiles of spontaneously healed AD to be comparable to healthy control skin, without upregulation of typical AD activity markers (e.g., IL13, S100As, and KRT16). Among all cell types in spontaneously healed AD, melanocytes harbored the largest numbers of differentially expressed genes in comparison to healthy controls, with upregulation of potentially anti-inflammatory markers such as PLA2G7. Conventional T-cells also showed increases in regulatory markers, and a general skewing toward a more Th1-like phenotype. By contrast, gene expression of regulatory T-cells and keratinocytes was essentially indistinguishable from healthy skin. Melanocytes and conventional T-cells might thus contribute a specific regulatory milieu in spontaneously healed AD skin.
Project description:Atopic dermatitis (AD) is the most common chronic inflammatory skin disease with complex pathogenesis. Using spatial and single-cell transcriptomics of whole skin biopsy and suction blister material, we investigated the cellular and molecular features of the leukocyte-infiltrated area in AD. We identified unique clusters of fibroblasts, dendritic cells, macrophages, and T cells in the lesional AD skin and molecular interactions between these cells. The leukocyte-infiltrated areas in lesional AD skin showed upregulation of COL6A5, COL4A1, TNC, IL32, CCL19 in COL18A1-expressing fibroblasts. Additionally, M2 macrophages expressed CCL13 and CCL18 in the same localization. Ligand–receptor interaction analysis of the spatial transcriptome identified a neighboring infiltration and interaction between activated COL18A1-expressing fibroblasts, activated CCL13- and CCL18-expressing M2 macrophages, CCR7- and LAMP3-expressing DCs, and T cells. As observed in skin lesions, serum levels of TNC and CCL18 were significantly elevated in AD and correlated with clinical disease severity.
Project description:Gold nanoparticles (GNPs) have been used in the development of novel therapies as a way of delivery of both stimulatory and tolerogenic peptide cargoes. Here we report that intradermal injection of GNPs loaded with the proinsulin peptide C19-A3, in patients with type 1 diabetes, results in recruitment and retention of immune cells in the skin. These include large numbers of clonally expanded T-cells sharing the same paired T-cell receptors (TCRs) with activated phenotypes, half of which, when the TCRs were re-expressed in a cell-based system, were confirmed to be specific for either GNP or proinsulin. All the identified gold-specific clones were CD8+, whilst proinsulin-specific clones were both CD8+ and CD4+. Proinsulin-specific CD8+ clones had a distinctive cytotoxic phenotype with overexpression of granulysin (GNLY) and KIR receptors. Clonally expanded antigen-specific T cells remained in situ for months to years, with a spectrum of tissue resident memory and effector memory phenotypes. As the T-cell response is divided between targeting the gold core and the antigenic cargo, this offers a route to improving resident memory T-cells formation in response to vaccines. In addition, our scRNAseq data indicate that focusing on clonally expanded skin infiltrating T-cells recruited to intradermally injected antigen is a highly efficient method to enrich and identify antigen-specific cells. This approach has the potential to be used to monitor the intradermal delivery of antigens and nanoparticles for immune modulation in humans the Enhanced Epidermal Antigen Specific Immunotherapy Trial -1 (EEASI) study was a two-centre, open-label, uncontrolled, single-group first-in-human Phase 1A safety study of C19-A3 GNP peptide in individuals with T1D (https://clinicaltrials.gov/ct2/show/NCT02837094). The investigational medicinal product (IMP) was C19-A3 GNP (Midacore™), which comprises Midacore™ GNPs (Midatech Pharma Plc, Cardiff, UK)(1, 20) of a size of less than 5 nm, covalently coupled to an 18-amino acid human peptide, the sequence of which is identical to the residues from position 19 in the C-peptide of proinsulin through to position 3 on the A-chain of the same molecule (GSLQPLALEGSLQKRGIV). The peptide is synthesised with a linker to facilitate binding to the GNPs: 3-mercaptopropionyl-SLQPLALEGSLQKRGIV 2 acetate salt (disulfide bond). The chemical composition of the IMP contained a ratio of 4 C19-A3 peptides: 11 glucose C2: 29 glutathione ligands as determined by 1H-NMR (proton nuclear magnetic resonance). A typical batch contained: [C19-A3 peptide] = 1.33 mg/ml; [gold] = 5.5 mg/ml; [glucose linker] = 0.6 mg/ml; [glutathione linker] = 1.79 mg/ml. As the drug substance was diluted 1:7 to 1:10, depending on the content of C19-A3 peptide per particle, and as 50 μl of the diluted solution was administered to the study participants, this corresponded to C19-A3 peptide: 10 μg; gold: 39 μg; glucose linker: 4.3 μg; glutathione: 12.7 μg. Participants diagnosed with T1D and confirmed to possess the HLA-DRB1∗0401 genotype, were given three doses of C19-A3 GNP at 4-weekly intervals (weeks 0, 4, and 8) in the deltoid region of alternate arms (2 doses in one arm and 1 dose in the other arm) via CE-marked 600 μm length MicronJet600™ hollow microneedles (NanoPass Technologies Ltd. Israel) attached to a standard Luer-lock syringe. The single-dose given in 50 μl volume was equivalent to 10 μg of C19-A3 peptide Skin suction blisters were raised: Briefly, suction cups were applied to the deltoid region of participants’ arms, at the site of previous injection. Skin suction blisters were performed by gradually applying negative pressure (up to 60 kPa) from a suction pump machine VP25 (Eschmann, Lancing, UK) through a suction blister cup with a 15-mm hole in the base (UHBristol NHS Foundation Trust Medical Engineering Department, Bristol, UK) for 2–4 hr until a unilocular blister had formed within the cup. The cup was left in place for a further 30-60 minutes to encourage migration of lymphocytes into the blister fluid. The cup was then removed, and the blister fluid aspirated using a needle and syringe. Blister fluid was immediately suspended in 10ml heparinised RPMI (Gibco)+ 5% foetal calf serum Cells were counted then washed once and resuspended in an appropriate volume for scRNAseq. Samples were used fresh on the day of the collection. Samples were processed using a 10xGenomics V1 human 5’GEX kit and libraries were constructed following standard 10xGenomics protocols. Samples were pooled and sequenced on Illumina NextSeq and MiSeq scRNAseq libraries were sequenced aiming for 20,000 reads per cell for GEX and 5,000 reads/cell for VDJ.
Project description:We performed a targeted proteomics analysis of Cutaneous Lupus Erythematosus (CLE) patient blister biopsies and plasma using Olink Proteomics panels to validate the blister biopsy technique using previously identified biomarkers, to confirm protein-level expression of biomarkers previously identified at the RNA level, and to identify new biomarkers of disease.
Project description:We performed a targeted proteomics analysis of Cutaneous Lupus Erythematosus (CLE) patient blister biopsies and plasma using Olink Proteomics panels to validate the blister biopsy technique using previously identified biomarkers, to confirm protein-level expression of biomarkers previously identified at the RNA level, and to identify new biomarkers of disease.
Project description:To probe the phenotype of the cDC compartment during pathology, we developed a simplified human experimental skin blister model to sample infiltrating cells in order to examine the function and kinetics of DC populations in response to a bacterial insult in healthy individuals. ASDC were recruited to the inflammatory site, displaying a distinctive effector signature. Human Skin Blister 1.5 x 107 UV killed E.coli (Strain: NCTC 10418, Source: Public Health England, UK) in 100 µl sterile saline was intradermally injected into the forearm approximately 7 cm from the cubital fossa. For the suction blister, a 10 mm diameter suction blister was induced at 24 hours post challenge over the injection site by a negative pressure instrument. Once a blister formed, blister exudate was collected, cells were isolated. Next, Blister cells were stained for DC subsets and index sorted on FACS ARIA III (BD Biosciences) into 96 well plate containing lysis buffer, one cell/well - using the gating strategy in Supplementary Figure 1a. Plates were sealed and stored at -80°C. Single-cell cDNA libraries were prepared using the SMARTSeq v2 protocol (Picelli et al., 2014) with the following modifications: (i) 1 mg/mL BSA Lysis buffer (Ambionâ Thermo Fisher Scientific); and (ii) 200 pg cDNA with 1/5 reaction of Illumina Nextera XT kit (Illumina, San Diego, CA, USA). The length distribution of the cDNA libraries was monitored using a DNA High Sensitivity Reagent Kit on the Perkin Elmer Labchip (Perkin Elmer, Waltham, MA, USA). All samples were subjected to an indexed paired-end sequencing run of 2x151 cycles on an Illumina HiSeq 4000 system (Illumina, San Diego, CA, USA), with 300 samples/lane. Pre-processing, quality assessment and control and analysis of SMARTseq2 single cell transcriptome data. Paired-end raw reads were aligned to the human reference genome (GRCh38 version 25 release: Gencode) using RSEM version 1.3.0. Transcript Per Million read (TPM) values were calculated using RSEM and used for downstream analysis. Quality control, selection of highly variable genes, PCA, and differential gene analysis was performed using the Seurat R package. The expression levels of key signature genes by known cell types was used to annotate the cell clusters accordingly.
Project description:Background: Skin biopsies represent a gold standard in skin immunology and pathology but can cause pain and induce scarring. Non-invasive techniques will facilitate study recruitment of e.g. patients with pediatric atopic dermatitis (AD), hand eczema or facial dermatitis. Objective: By RNA sequencing, we examined whether the stratum corneum transcriptome in AD skin can be assessed by tape stripping, as compared to the epidermal transcriptome of AD in skin biopsies. To make the procedure clinically relevant tape strips were stored and shipped at room temperature for up to 3 days. Methods: Nine adult Caucasian AD patients and three healthy volunteers were included. Tape samples were collected from non-lesional and lesional skin. Biopsies were collected from lesional skin and were split into epidermis and dermis. Total RNA was extracted, and shotgun sequencing was performed. Results: Shotgun sequencing could be performed on skin cells obtained from two consecutive tape strips which had been stored and shipped at room temperature for up to three days. The most prominent differences between the tape strip and biopsy derived transcriptome were due to structural genes, while established molecular markers of AD, including CCL17, CCL22, IL17A and S100A7-S100A9, were also identified in tape strip samples. Furthermore, the tape strip derived transcriptome showed promise in also analysing the skin microbiome. Conclusion: Our study shows that the stratum corneum (SC) transcriptome of AD can be assessed by tape stripping the skin, supporting that this method may be central in future skin biomarker research.
Project description:Severe cutaneous adverse reactions (SCAR) are rare but life-threatening drug reactions mediated by human leukocyte antigen (HLA) class I-restricted CD8+ T-cells. To obtain an unbiased assessment of SCAR cellular immunopathogenesis, we performed single-cell (sc) transcriptome, surface proteome, and TCR sequencing (5' scRNA-TCR-CITE-seq, 10x Genomics) on unaffected skin, affected skin, and blister fluid from diverse SCAR patients.
Project description:Atopic dermatitis (AD) is a heritable inflammatory disease, characterised by skin barrier dysfunction. Genome-wide association studies (GWAS) have identified molecular targets with relevance for drug development, but the strongest genetic association, FLG, has not yet been successfully targeted in atopic disease. An AD-associated locus on chromosome 11q13.5 lies between two genes - EMSY and LRRC32 - but the functional mechanisms leading to AD are unclear. We applied a combination of genomic and molecular analytical techniques followed up in patient biopsies, to investigate pathomechanisms at this GWAS locus. Chromosome conformation capture data in keratinocytes shows interaction of the intergenic region in threedimensional space with EMSY. siRNA-mediated knockdown of EMSY in skin organoid culture leads to enhanced development of barrier function, measured by water evaporation and dye penetration. Global proteomic analysis of skin organoids with EMSY knockdown shows increased expression of structural and functional proteins, confirmed by histological and ultrastructural features. Lipid analysis shows an increase in ceramides known to be reduced in AD. Conversely, over-expression of EMSY in primary human keratinocytes leads to a reduction in biomarkers of barrier formation. Finally, skin biopsy samples from patients with AD show greater EMSY staining in the nucleus, consistent with increased functional effect of this DNAbinding protein. Together our findings demonstrate an important role for EMSY in transcriptional regulation and skin barrier formation, supporting EMSY inhibition as a therapeutic approach for AD.