Single-cell transcriptomics combined with interstitial fluid proteomics defines cell type-specific immune regulation in atopic dermatitis

Comparative Analysis of HMC3 and C20 Microglial Cell Lines Reveals Differential Myeloid Characteristics and Responses to Immune Stimuli

Microglia are the primary resident immune cells of the central nervous system (CNS) that respond to injury and infections. Being critical to CNS homeostasis, microglia also have been shown to contribute to neurodegenerative diseases and brain cancer. Hence, microglia are regarded as a potential therapeutic target in CNS diseases, resulting in an increased demand for reliable in vitro models. Two human microglia cell lines (HMC3 and C20) are being used in multiple in vitro studies, however, the knowledge of their biological and immunological characteristics remains limited. Our aim was to identify and compare the biological changes in these immortalised immune cells under normal physiological and immunologically challenged conditions. Using high-resolution quantitative mass spectrometry, we have examined in-depth proteomic profiles of non-stimulated and LPS or IFN-γ challenged HMC3 and C20 cells. Our findings reveal that HMC3 cells responded to both treatments through upregulation of immune, metabolic, and antiviral pathways, while C20 cells showed a response associated with mitochondrial and immune activities. Additionally, the secretome analysis demonstrated that both cell lines release IL-6 in response to LPS, while IFN-γ treatment resulted in altered kynurenine pathway activity, highlighting distinct immune and metabolic adaptations.

Spatial Transcriptomics Identifies Immune-Stromal Niches Associated with Cancer in Adult Dermatomyositis

Adult-onset dermatomyositis (DM) is an autoimmune inflammatory myopathy with distinct cutaneous manifestations and a strong malignancy association. Through comparative analysis with cutaneous lupus erythematosus (CLE), our integrated spatial and single-cell transcriptomics analysis revealed unique immune and stromal niches associated with DM subtypes. Unexpectedly, we found an association between cancer-associated DM skin lesions and the presence of dispersed immune infiltrates enriched with macrophages, CD8+ T cells, plasma cells, and B cells with preserved vascular architecture. In contrast, non-cancer associated DM skin exhibited dense myeloid cell infiltrates, including neutrophils, monocytes, and macrophages, with elevated expression of IL1B and CXCL10 localized near injured vascular endothelia. Cytokines produced by these myeloid infiltrates together with local tissue hypoxia triggered dramatic stromal remodeling, leading to loss of vascular-associated fibroblasts. In addition to the CXCL10+ myeloid signature, non-cancer-associated DM skin with pDC presence showed the emergence of specific cellular pairs: PD-L1-expressing mregDCs and activated Tregs expressing NFKB2 and TNF receptors. While both DM and CLE showed strong interferon signatures, DM uniquely displayed IFN-β expression. Together, our study provides the first comprehensive spatial mapping of immune and stromal cells in adult-onset DM.

Combined transcriptomic and proteomic analyses reveal relevant myelin features in mice with ischemic stroke

Ischemic stroke (IS), a leading cause of global disability and mortality, is characterized by white matter damage and demyelination. Despite advances, the molecular mechanisms driving post-IS myelin pathology remain poorly understood, limiting therapeutic development. This study investigates key myelin-related genes (MRGs) and their regulatory networks to identify novel therapeutic targets. A transient middle cerebral artery occlusion (MCAO) model was established in C57BL/6 mice, with brain tissues collected at four timepoints (Sham0D, MCAO0D, MCAO7D, MCAO14D). Transcriptomic and proteomic sequencing were performed, followed by soft clustering (Mfuzz), functional enrichment (GO/KEGG), and ROC analysis to identify key MRGs. Competing endogenous RNA (ceRNA) networks were constructed, and drug prediction was conducted using the Comparative Toxicogenomics Database (CTD) and molecular docking. Expression validation was performed via qRT-PCR and Western blot. Integrated multi-omics analysis identified Wasf3 and Slc25a5 as key MRGs, enriched in mitochondrial respiration, calcium metabolism, and cytoskeletal regulation. The AUC values of the one-to-one model scores were all greater than 0.7, suggesting that Wasf3 and Slc25a5 were able to effectively discriminate between samples from different time points. A ceRNA network revealed critical interactions, including the Wasf3-mmu-miR-423-5p-H19 axis, linking apoptosis and myelin dysfunction. Drug prediction highlighted valproic acid (VPA) as a high-affinity binder for both genes (binding energies: - 4.2 and - 4.7 kcal/mol), suggesting its potential as a therapeutic candidate for IS. Experimental validation confirmed significant downregulation of Wasf3 mRNA (p < 0.01) and protein (p = 0.069) post-IS, while Slc25a5 showed no significant changes, potentially due to sample size limitations. This study establishes Wasf3 and Slc25a5 as pivotal regulators of post-IS myelin pathology and proposes VPA as a promising therapeutic candidate to enhance remyelination. The findings underscore the utility of multi-omics approaches in bridging molecular mechanisms to clinical translation, offering new strategies for IS diagnosis and treatment.

Type 2 immunity in allergic diseases

Significant advancements have been made in understanding the cellular and molecular mechanisms of type 2 immunity in allergic diseases such as asthma, allergic rhinitis, chronic rhinosinusitis, eosinophilic esophagitis (EoE), food and drug allergies, and atopic dermatitis (AD). Type 2 immunity has evolved to protect against parasitic diseases and toxins, plays a role in the expulsion of parasites and larvae from inner tissues to the lumen and outside the body, maintains microbe-rich skin and mucosal epithelial barriers and counterbalances the type 1 immune response and its destructive effects. During the development of a type 2 immune response, an innate immune response initiates starting from epithelial cells and innate lymphoid cells (ILCs), including dendritic cells and macrophages, and translates to adaptive T and B-cell immunity, particularly IgE antibody production. Eosinophils, mast cells and basophils have effects on effector functions. Cytokines from ILC2s and CD4+ helper type 2 (Th2) cells, CD8 + T cells, and NK-T cells, along with myeloid cells, including IL-4, IL-5, IL-9, and IL-13, initiate and sustain allergic inflammation via T cell cells, eosinophils, and ILC2s; promote IgE class switching; and open the epithelial barrier. Epithelial cell activation, alarmin release and barrier dysfunction are key in the development of not only allergic diseases but also many other systemic diseases. Recent biologics targeting the pathways and effector functions of IL4/IL13, IL-5, and IgE have shown promising results for almost all ages, although some patients with severe allergic diseases do not respond to these therapies, highlighting the unmet need for a more detailed and personalized approach.

Inflammation switches the chemoattractant requirements for naive lymphocyte entry into lymph nodes

Sustained lymphocyte migration from blood into lymph nodes (LNs) is important for immune responses. The CC-chemokine receptor-7 (CCR7) ligand CCL21 is required for LN entry but is downregulated during inflammation, and it has been unclear how recruitment is maintained. Here, we show that the oxysterol biosynthetic enzyme cholesterol-25-hydroxylase (Ch25h) is upregulated in LN high endothelial venules during viral infection. Lymphocytes become dependent on oxysterols, generated through a transcellular endothelial-fibroblast metabolic pathway, and the receptor EBI2 for inflamed LN entry. Additionally, Langerhans cells are an oxysterol source. Ch25h is also expressed in inflamed peripheral endothelium, and EBI2 mediates B cell recruitment in a tumor model. Finally, we demonstrate that LN CCL19 is critical in lymphocyte recruitment during inflammation. Thus, our work explains how naive precursor trafficking is sustained in responding LNs, identifies a role for oxysterols in cell recruitment into inflamed tissues, and establishes a logic for the CCR7 two-ligand system.

Comparison of CD30L and OX40L Reveals CD30L as a Promising Therapeutic Target in Atopic Dermatitis

BACKGROUND

Blocking IL-13 is highly efficacious in patients with Th2-biased atopic dermatitis (AD), and recent clinical data have highlighted that targeting the T cell costimulatory molecules OX40 and OX40L (TNFSF4) holds promise for future treatment of AD.

AIM

We asked whether targeting another T cell costimulatory molecule, CD30L (TNFSF8), might also be a possible treatment option in AD.

METHODS

Single-cell RNA-seq data from human AD skin lesions was analyzed to identify pathogenic IL-13- or IL-22-producing T cells and assess expression of CD30 and its ligand in comparison to OX40 and its ligand. Additionally, a murine model of AD with repetitive exposure to house dust mite allergen was used to compare neutralizing antibodies against CD30L with those against IL-13 or OX40L.

RESULTS

Analysis of several scRNA-seq datasets from skin lesions of AD patients showed that transcripts for CD30 or CD30L were found expressed with OX40 or OX40L in the primary T cell populations that also expressed mRNA for IL13 and/or IL22. Suggesting that this could be therapeutically relevant, mice treated prophylactically with a blocking CD30L antibody were protected from developing maximal allergen-induced AD features, including epidermal and dermal thickening, immune cell infiltration, and expression of AD-related genes, similar to mice treated with a blocking IL-13 antibody. Moreover, therapeutic neutralization of CD30L in mice with experimental AD also reduced all of the pathological skin lesion features to a comparable extent as blocking OX40L.

CONCLUSION

These data suggest that targeting the CD30-CD30L axis might hold promise as a future therapeutic intervention in human AD, similar to targeting the OX40-OX40L axis.

How type-2 dendritic cells induce Th2 differentiation: Instruction, repression, or fostering T cell-T cell communication?

Allergic disease is caused by the activation of allergen-specific CD4+ type-2 T follicular helper cells (Tfh2) and T helper 2 (Th2) effector cells that secrete the cytokines IL-4, IL-5, IL-9, and IL-13 upon allergen encounter, thereby inducing IgE production by B cells and tissue inflammation. While it is accepted that the priming and differentiation of naïve CD4+ T cells into Th2 requires allergen presentation by type 2 dendritic cells (DC2s), the underlying signals remain unidentified. In this review we focus on the interaction between allergen-presenting DC2s and naïve CD4+ T cells in lymph node (LN), and the potential mechanisms by which DC2s might instruct Th2 differentiation. We outline recent advances in characterizing DC2 development and heterogeneity. We review mechanisms of allergen sensing and current proposed mechanisms of Th2 differentiation, with specific consideration of the role of DC2s and how they might contribute to each mechanism. Finally, we assess recent publications reporting a detailed analysis of DC-T cell interactions in LNs and how they support Th2 differentiation. Together, these studies are starting to shape our understanding of this key initial step of the allergic immune response.

Single-cell sequencing delineates T-cell clonality and pathogenesis of the parapsoriasis disease group

BACKGROUND

Mycosis fungoides (MF), the most common cutaneous T-cell lymphoma, is often underdiagnosed in early stages because of similarities with benign dermatoses such as atopic dermatitis (AD). Furthermore, the delineation from what is called "parapsoriasis en plaque", a disease that can appear either in a small- or large-plaque form, is still controversial.

OBJECTIVE

We sought to characterize the parapsoriasis disease spectrum.

METHODS

We performed single-cell RNA sequencing of skin biopsies from patients within the parapsoriasis-to-early-stage MF spectrum, stratified for small and large plaques, and compared them to AD, psoriasis, and healthy control skin.

RESULTS

Six of 8 large-plaque lesions harbored either an expanded alpha/beta or gamma/delta T-cell clone with downregulation of CD7 expression, consistent with a diagnosis of early-stage MF. In contrast, 6 of 7 small-plaque lesions were polyclonal in nature, thereby lacking a lymphomatous phenotype, and also revealed a less inflammatory microenvironment than early-stage MF or AD. Of note, polyclonal small- and large-plaque lesions characteristically harbored a population of NPY+ innate lymphoid cells and displayed a stromal signature of complement upregulation and antimicrobial hyperresponsiveness in fibroblasts and sweat gland cells, respectively. These conditions were clearly distinct from AD or psoriasis, which uniquely harbored CD3+CRTH2+ IL-13 expressing "TH2A" cells, or strong type 17 inflammation, respectively.

CONCLUSION

These data position polyclonal small- and large-plaque parapsoriasis lesions as a separate disease entity that characteristically harbors a so far undescribed innate lymphoid cell population. We thus propose a new term, "polyclonal parapsoriasis en plaque", for this kind of lesion because they can be clearly differentiated from early- and advanced-stage MF, psoriasis, and AD on several cellular and molecular levels.

Unveiling Novel Protein Biomarkers for Psoriasis Through Integrated Analysis of Human Plasma Proteomics and Mendelian Randomization

Background

Current pharmacological treatments for psoriasis are generally non-specific and have significant limitations, particularly in the realm of targeted biologic therapies. There is an urgent need to identify and develop new therapeutic targets to improve treatment options.

Objective

The aim of this study was to explore the proteome associated with psoriasis in large population cohorts to discover novel biomarkers that could guide therapy.

Methods

We analyzed data from 54,306 participants enrolled in the UK Biobank Pharmacological Proteomics Project (UKB-PPP). We investigated the relationship between 2923 serum proteins and the risk of psoriasis using multivariate Cox regression models initially. This was complemented by two-sample Mendelian randomization (TSMR), Summary-data-based Mendelian Randomization (SMR), and coloc colocalization studies to identify genetic correlations with protein targets linked to psoriasis. A protein scoring system was created using the Cox proportional hazards model, and cumulative risk curves were generated to analyze psoriasis incidence variations.

Results

Our study pinpointed 62 proteins significantly linked to the risk of developing psoriasis. Further analysis through TSMR narrowed these down to ten proteins with strong causal relationships to the disease. Additional deep-dive analyses such as SMR, colocalization, and differential expression studies highlighted four critical proteins (MMP12, PCSK9, PRSS8, and SCLY). We calculated a protein score based on the levels of these proteins, with higher scores correlating with increased risk of psoriasis.

Conclusion

This study's integration of proteomic and genetic data from a European adult cohort provides compelling evidence of several proteins as viable predictive biomarkers and potential therapeutic targets for psoriasis, facilitating the advancement of targeted treatment strategies.

Therapeutic potential of plasma-treated solutions in atopic dermatitis

Atopic Dermatitis (AD) is a prevalent inflammatory skin disease that is currently incurable. Plasma-treated solutions (PTS) (e.g., culture media, water, or normal saline, previously exposed to plasma) are being studied as novel therapy. Recently, PTS is gaining attention due to its advantages over non-thermal plasma (also known as cold atmospheric plasma). Thus, we explore the application of PTS in treating AD. In vivo experiments demonstrated that PTS significantly alleviated AD-like symptoms. It reduced mast cell and macrophage infiltration, decreased scratching times and serum IgE levels. These therapeutic effects of PTS on AD mice were associated with the activation of the antioxidant molecule Nrf2. In vitro experiments revealed that PTS could decrease ROS level and regulate cytokine expression (such as IL-6, IL-10, IL-13 and CCL17) in TNF-α/IFN-γ-stimulated keratinocytes and LPS-stimulated M1 macrophages. Additionally, PTS could upregulate the expression of antioxidant stress molecules such as Nrf2, HO-1, NQO1 and PPAR-γ in both cell types. Overall, PTS demonstrated potent therapeutic potential for AD without notable side effects. Our research provided a promising approach to AD treatment and may serve as a potential therapeutic strategy in other inflammatory skin diseases.

A cost-effective protocol for single-cell RNA sequencing of human skin

Introduction

Single-cell RNA sequencing (scRNAseq) and flow cytometry studies in skin are methodologically complex and costly, limiting their accessibility to researchers worldwide. Ideally, RNA and protein-based analyses should be performed on the same lesion to obtain more comprehensive data. However, current protocols generally focus on either scRNAseq or flow cytometry of healthy skin.

Methods

We present a novel label-free sample multiplexing strategy, building on the souporcell algorithm, which enables scRNAseq analysis of paired blood and skin samples. Additionally, we provide detailed instructions for simultaneous flow cytometry analysis from the same sample, with necessary adaptations for both healthy and inflamed skin specimens.

Results

This tissue multiplexing strategy mitigates technical batch effects and reduces costs by 2-4 times compared to existing protocols. We also demonstrate the effects of varying enzymatic incubation durations (1, 3, and 16 hours, with and without enzyme P) on flow cytometry outcomes. Comprehensive explanations of bioinformatic demultiplexing steps and a detailed step-by-step protocol of the entire experimental procedure are included.

Discussion

The protocol outlined in this article will make scRNAseq and flow cytometry analysis of skin samples more accessible to researchers, especially those new to these techniques.

Differences in cell subsets between sun-exposed and unexposed skin: preliminary single-cell sequencing and biological analysis from a single case

Introduction

The composition and subsets of skin cells continuously change in a dynamic manner. However, the specific microcosmic alterations of human photoaged skin, independent of chronologic aging, remain unclear and have been infrequently analyzed. This study aimed to evaluate the biological processes and mechanisms underlying cell-subgroup alterations in skin photoaging.

Methods

We utilized single-cell sequencing and biological analysis from a single case to investigate the effects of photoaging. Skin punch biopsies were taken from sun-exposed forearm skin and unexposed buttock skin from the same individual for comparative analysis.

Results

Our analysis identified 25 cell clusters and 12 skin cell types, revealing significant changes in unique gene expressions between the sun-exposed and unexposed skin samples. A comparison of cell numbers within each cluster revealed 9 dominant cell clusters in sun-exposed skin and 16 dominant cell clusters in unexposed skin. Enrichment analysis indicated that PD-L1 expression and the PD-1 checkpoint pathway were more prominent in sun-exposed skin, while MAPK, TNF-alpha, TGF-beta, and apoptosis pathways were more enriched in hair follicle cells of sun-exposed skin.

Discussion

This study reveals changes in cell components in photoaged skin from a single case and provides novel insights into cellular subpopulations and pathology during repeated UVA-induced skin damage. These findings enhance our understanding of the complex interplay between different cells in photoaged skin and offer potential targets for preventing human skin photoaging and UV-induced skin cancers.

Unveiling new protein biomarkers and therapeutic targets for acne through integrated analysis of human plasma proteomics and genomics

Background

The current landscape of acne therapeutics is notably lacking in targeted treatments, highlighting a critical need for the discovery of new drug targets to improve treatment outcomes.

Objectives

This study aims to investigate the connections between proteomics and genetics in relation to acne across extensive population cohorts, aspiring to identify innovative preventive and therapeutic approaches.

Methods

Employing a longitudinal cohort of 54,306 participants from the UK Biobank Pharmacological Proteomics Project (UKB-PPP), we performed an exhaustive evaluation of the associations between 2,923 serum proteins and acne risk. Initial multivariate Cox regression analyses assessed the relationship between protein expression levels and acne onset, followed by two-sample Mendelian Randomization (TSMR), Summary-data-based Mendelian Randomization (SMR), and colocalization to identify genetic correlations with potential protein targets.

Results

Within the UKB cohort, we identified 19 proteins significantly associated with the risk of acne. Subsequent analysis using Two-Sample Mendelian Randomization (TSMR) refined this to two specific proteins: FSTL1 and ANXA5. Each one-standard deviation increase in the expression levels of FSTL1 and ANXA5 was associated with a 24% and 32% increase in acne incidence, respectively. These results were further validated by additional Summary-data-based Mendelian Randomization (SMR) and differential expression analyses.

Conclusions

Our comprehensive analysis of proteomic and genetic data from a European adult cohort provides compelling causal evidence that several proteins are promising targets for novel acne treatments.

Multiomic single-cell sequencing defines tissue-specific responses in Stevens-Johnson syndrome and toxic epidermal necrolysis

Stevens-Johnson syndrome and toxic epidermal necrolysis (SJS/TEN) is a rare but life-threatening cutaneous drug reaction mediated by human leukocyte antigen (HLA) class I-restricted CD8+ T cells. For unbiased assessment of cellular immunopathogenesis, here we perform single-cell (sc) transcriptome, surface proteome, and T cell receptor (TCR) sequencing on unaffected skin, affected skin, and blister fluid from 15 SJS/TEN patients. From 109,888 cells, we identify 15 scRNA-defined subsets. Keratinocytes express markers indicating HLA class I-restricted antigen presentation and appear to trigger the proliferation of and killing by cytotoxic CD8+ tissue-resident T cells that express granulysin, granzyme B, perforin, LAG3, CD27, and LINC01871, and signal through the PKM, MIF, TGFβ, and JAK-STAT pathways. In affected tissue, cytotoxic CD8+ T cells express private expanded and unexpanded TCRαβ that are absent or unexpanded in unaffected skin, and mixed populations of macrophages and fibroblasts express pro-inflammatory markers or those favoring repair. This data identifies putative cytotoxic TCRs and therapeutic targets.

Unraveling the Functional Heterogeneity of Human Skin at Single-Cell Resolution

The skin consists of several cell populations, including epithelial, immune, and stromal cells. Recently, there has been a significant increase in single-cell RNA-sequencing studies, contributing to the development of a consensus Human Skin Cell Atlas. The aim is to understand skin biology better and identify potential therapeutic targets. The present review utilized previously published single-cell RNA-sequencing datasets to explore human skin's cellular and functional heterogeneity. Additionally, it summarizes the functional significance of newly identified cell subpopulations in processes such as wound healing and aging.

Skin sensing and wearable technology as tools to measure atopic dermatitis severity

Wearable medical technology encompasses a range of electronic devices that act as biosensors. Atopic dermatitis (AD) is the commonest inflammatory skin disease and represents an important area of need in which to leverage the power of wearable biosensor technology, especially as the impact of COVID-19 increases the likelihood of virtual consultations becoming an integrated part of clinical practice. The aim of this review is to systematically define the published evidence for the utility of wearable biosensors in assessment and management of atopic dermatitis (AD). A systematic literature search was conducted for publications from 1995 onwards for 'sensor' OR 'sensing' OR 'biosensor' OR 'biomarker'. Results were combined ('AND') with a search for 'wearable' OR 'actigraphy' OR 'Internet of things' OR 'microneedle' OR 'patch' OR 'e-textile' OR 'smart textile' and atopic dermatitis (MESH terms). Fifty seven abstracts were identified from the database search of which 39 were selected for detailed review. Broadly, wearable sensing systems in atopic dermatitis were split into three categories: wearable biosensor modules (actigraphy and smartwatches), clothing and integrated fabrics placed onto the epidermis and intradermal or subcutaneous sensors. The best evidence for correlation with AD disease severity was with actigraphy measurements of itch. However, newer approaches including sensing skin barrier function, inflammation and small molecule analysis as well as employing artificial intelligence offer more potential for advanced disease monitoring. Skin diseases, specifically AD, stand to benefit greatly from wearable technology, because of the ease of direct contact to the skin, the high prevalence of the disease and the large unmet need for better disease control in this group. However, important emphasis must be placed on validating the correlation of data from such technology with patient-reported outcomes. Wearable biosensors offer a huge potential to deliver better diagnostics, monitoring and treatment outcomes for patients.

Single cell RNA sequencing of human eosinophils from nasal polyps reveals eosinophil heterogeneity in chronic rhinosinusitis tissue

BACKGROUND

Chronic rhinosinusitis with nasal polyps (CRSwNP) is characterized by type 2 inflammation in the United States, but the actual roles that eosinophils play in CRSwNP remain largely unclear.

OBJECTIVE

To reveal the roles and heterogeneity of eosinophils in nasal polyp (NP) tissue, we performed single cell RNA sequencing (scRNA-Seq) analysis of NP tissue.

METHODS

Sinonasal tissues (NP and control sinus tissue) and patient matched peripheral blood (PB) samples were obtained from 5 control patients and 5 patients with CRSwNP. Eosinophils were enriched before processing for scRNA-Seq. The gene expression profiles in eosinophils were determined by microwell-based scRNA-Seq technology (BD Rhapsody platform). We predicted the overall function of NP eosinophils by Gene Ontology (geneontology.org) enrichment and pathway analyses and confirmed expression of selected genes by flow cytometry.

RESULTS

After filtering out contaminating cells, we detected 5,542 eosinophils from control PB, 3,883 eosinophils from CRSwNP PB, 101 eosinophils from control sinus tissues (not included in further analyses), and 9,727 eosinophils from NPs by scRNA-Seq. We found that 204 genes were downregulated and 354 genes upregulated in NP eosinophils compared to all PB eosinophils (>1.5-fold, Padj < .05). Upregulated genes in NP eosinophils were associated with activation, cytokine-mediated signaling, growth factor activity, NF-κB signaling, and antiapoptotic molecules. NP eosinophils displayed 4 clusters revealing potential heterogeneity of eosinophils in NP tissue.

CONCLUSIONS

Elevated eosinophils in NP tissue appear to exist in several subtypes that may play important pathogenic roles in CRSwNP, in part by controlling inflammation and hyperproliferation of other cells.

Inflammatory Mediators Suppress FGFR2 Expression in Human Keratinocytes to Promote Inflammation

Fibroblast growth factors (FGFs) are key orchestrators of development, tissue homeostasis and repair. FGF receptor (FGFR) deficiency in mouse keratinocytes causes an inflammatory skin phenotype with similarities to atopic dermatitis, but the human relevance is unclear. Therefore, we generated human keratinocytes with a CRISPR/Cas9-induced knockout of FGFR2. Loss of this receptor promoted the expression of interferon-stimulated genes and pro-inflammatory cytokines under homeostatic conditions and in particular in response to different inflammatory mediators. Expression of FGFR2 itself was strongly downregulated in cultured human keratinocytes exposed to various pro-inflammatory stimuli. This is relevant in vivo, because bioinformatics analysis of bulk and single-cell RNA-seq data showed strongly reduced expression of FGFR2 in lesional skin of atopic dermatitis patients, which likely aggravates the inflammatory phenotype. These results reveal a key function of FGFR2 in human keratinocytes in the suppression of inflammation and suggest a role of FGFR2 downregulation in the pathogenesis of atopic dermatitis and possibly other inflammatory diseases.

Systemic comparison of molecular characteristics in different skin fibroblast senescent models

BACKGROUND

Senescent human skin primary fibroblast (FB) models have been established for studying aging-related, proliferative, and inflammatory skin diseases. The aim of this study was to compare the transcriptome characteristics of human primary dermal FBs from children and the elderly with four senescence models.

METHODS

Human skin primary FBs were obtained from healthy children (FB-C) and elderly donors (FB-E). Senescence models were generated by ultraviolet B irradiation (FB-UVB), D-galactose stimulation (FB-D-gal), atazanavir treatment (FB-ATV), and replication exhaustion induction (FB-P30). Flow cytometry, immunofluorescence staining, real-time quantitative polymerase chain reaction, co-culturing with immune cells, and bulk RNA sequencing were used for systematic comparisons of the models.

RESULTS

In comparison with FB-C, FB-E showed elevated expression of senescence-related genes related to the skin barrier and extracellular matrix, proinflammatory factors, chemokines, oxidative stress, and complement factors. In comparison with FB-E, FB-UVB and FB-ATV showed higher levels of senescence and expression of the genes related to the senescence-associated secretory phenotype (SASP), and their shaped immune microenvironment highly facilitated the activation of downstream immune cells, including T cells, macrophages, and natural killer cells. FB-P30 was most similar to FB-E in terms of general transcriptome features, such as FB migration and proliferation, and aging-related characteristics. FB-D-gal showed the lowest expression levels of senescence-related genes. In comparisons with the single-cell RNA sequencing results, FB-E showed almost complete simulation of the transcriptional spectrum of FBs in elderly patients with atopic dermatitis, followed by FB-P30 and FB-UVB. FB-E and FB-P30 showed higher similarity with the FBs in keloids.

CONCLUSIONS

Each senescent FB model exhibited different characteristics. In addition to showing upregulated expression of natural senescence features, FB-UVB and FB-ATV showed high expression levels of senescence-related genes, including those involved in the SASP, and FB-P30 showed the greatest similarity with FB-E. However, D-galactose-stimulated FBs did not clearly present aging characteristics.

Skin in the game: a review of single-cell and spatial transcriptomics in dermatological research

Single-cell RNA sequencing (scRNA-seq) and spatial transcriptomics (ST) are two emerging research technologies that uniquely characterize gene expression microenvironments on a cellular or subcellular level. The skin, a clinically accessible tissue composed of diverse, essential cell populations, serves as an ideal target for these high-resolution investigative approaches. Using these tools, researchers are assembling a compendium of data and discoveries in healthy skin as well as a range of dermatologic pathophysiologies, including atopic dermatitis, psoriasis, and cutaneous malignancies. The ongoing advancement of single-cell approaches, coupled with anticipated decreases in cost with increased adoption, will reshape dermatologic research, profoundly influencing disease characterization, prognosis, and ultimately clinical practice.

Integrating multi-omics approaches in deciphering atopic dermatitis pathogenesis and future therapeutic directions

Atopic dermatitis (AD), a complex and heterogeneous chronic inflammatory skin disorder, manifests in a spectrum of clinical subtypes. The application of genomics has elucidated the role of genetic variations in predisposing individuals to AD. Transcriptomics, analyzing gene expression alterations, sheds light on the molecular underpinnings of AD. Proteomics explores the involvement of proteins in AD pathophysiology, while epigenomics examines the impact of environmental factors on gene expression. Lipidomics, which investigates lipid profiles, enhances our understanding of skin barrier functionalities and their perturbations in AD. This review synthesizes insights from these omics approaches, highlighting their collective importance in unraveling the intricate pathogenesis of AD. The review culminates by projecting future trajectories in AD research, particularly the promise of multi-omics in forging personalized medicine and novel therapeutic interventions. Such an integrated multi-omics strategy is poised to transform AD comprehension and management, steering towards more precise and efficacious treatment modalities.

Adenosine A2A receptor activation regulates the M1 macrophages activation to initiate innate and adaptive immunity in psoriasis

Psoriasis is a common inflammatory systemic disease characterized by pro-inflammatory macrophages activation (M1 macrophage) infiltrated in the dermal layer. How M1 macrophage contributes to psoriasis remains unknown. In this study, we found that adenosine A2A receptor (A2AR) agonist CGS 21680 HCl alleviated the imiquimod (IMQ) and mouse IL-23 Protein (rmIL-23)-induced psoriasis inflammation through reducing infiltration of M1. Conversely, Adora2a deletion in mice exacerbated psoriasis-like phenotype. Mechanistically, A2AR activation inhibited M1 macrophage activation via the NF-κB-KRT16 pathway to reduce the secretion of CXCL10/11 and inhibit Th1/17 differentiation. Notably, the KRT16 expression was first found in M1 macrophage in our study, not only in keratinocytes (KCs). CXCL10/11 are first identified as primarily derived from macrophages and dendritic cells (DCs) rather than KCs in psoriasis using single cell RNA sequencing (scRNA-Seq). In total, the study emphasizes the importance of M1 as an innate immune cell in pathogenesis of psoriasis.

Schizonepeta tenuifolia Briq-Saposhnikovia divaricata decoction alleviates atopic dermatitis via downregulating macrophage TRPV1

Objective

Schizonepeta tenuifolia -Saposhnikovia divaricata (Jingjie-Fangfeng, JF) has been used for years to treat allergic inflammatory skin diseases like atopic dermatitis, but the specific effects and mechanisms of JF are still unclear.

Purpose

We aim to investigate the therapeutic effect and mechanism of JF in MC903-induced atopic dermatitis-like model.

Methods

JF decoction was subjected to rigorous HPLC and GC analysis. The JF decoction was then freshly prepared and administered to MC903-induced atopic dermatitis -like mice models to investigate its therapeutic effects. Our evaluation focused on several markers of inflammation including the TEWL index, ear thickness, swelling, and specific inflammation indicators such as TSLP, IL33, IgE, and immune cell presence at the lesion sites. We measured Transient Receptor Potential Vanilloid 1 (TRPV1) expression levels through immunofluorescent staining in skin tissue from both atopic dermatitis patients and the MC903-treated mice. Furthermore, TRPV1 expression and macrophage activation markers were measured in LPS/IFN-γ-stimulated Raw264.7 and THP-1 cell models in vitro. Additionally, we developed cell lines that overexpress TRPV1 and investigated how JF treatment affects NF-κB p65 phosphorylation in these cells to understand better the role of TRPV1 in atopic dermatitis.

Results

The JF decoction met the standards outlined in the Chinese pharmacopeia. The JF decoction significantly alleviated inflammatory skin symptoms and helped restore skin barrier function. Additionally, it reduced the levels of IgE and pro-inflammatory cytokines TSLP, IL-33, and IL-4. There was also a noticeable decrease in mast cell infiltration and degranulation. Notably, JF decoction reduced infiltrated macrophages with limited affection on T cell infiltration. It also decreased F4/80+/TRPV1+ cells in atopic dermatitis mice and TRPV1 expression in LPS/IFNγ-stimulated microphages. Additionally, we observed that CD68+/TRPV1+ cells increased in human atopic dermatitis tissue. Further studies showed that JF water extract (JF-WE) suppressed TRPV1 expression in macrophages, potentially by affecting NF-κB p65 phosphorylation rather than the JAK-STAT6 pathway.

Conclusion

This study offers initial evidence of the effectiveness of JF-WE in suppressing inflammation in atopic dermatitis. The therapeutic effect might stems from its ability to downregulate TRPV1 expression and subsequent NF-κB p65 phosphorylation in macrophages.

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.

Proteomic analysis of cardiovascular disease-associated proteins in Korean patients with moderate-to-severe atopic dermatitis

Background

Cardiovascular diseases (CVDs) have been associated with atopic dermatitis (AD), including in Korean patients. Previous studies on AD have primarily focused on patients of European ancestry, while the Asian endotype exhibits distinct characteristics. This study aimed to characterize the blood proteomic signature of Korean patients with moderate-to-severe AD, with an emphasis on proteins related to CVDs.

Methods

A total of 78 participants, including 39 patients with moderate-to-severe AD and 39 age- and sex-matched healthy controls, were enrolled. Blood proteomics analysis was performed using the Olink CVD II panel, which measures the expression levels of 92 proteins associated with CVDs.

Results

Unsupervised hierarchical clustering revealed 44 upregulated and 5 downregulated proteins in AD patients compared to healthy controls. Principal component analysis (PCA) effectively distinguished AD patients from healthy subjects based on the complete set of proteins or the subset of upregulated proteins. A multiple linear regression model comprising CCL17 and FGF21 showed a strong correlation with disease severity (R = 0.619). Correlation analysis identified 25 highly correlated proteins, including STK4, ITGB1BP2, and DECR1, which were newly found to be upregulated in Korean AD patients. Pathway analysis highlighted the involvement of these proteins in vascular system, inflammation, and lipid metabolism pathways.

Conclusion

The blood proteomic profile of moderate-to-severe AD patients in Korea differed from healthy controls using the CVD II panel. This study provides potential biomarkers for the AD-CVD association and insights into the pathways contributing to this relationship in the Korean population.

Authentication and validation of key genes in the treatment of atopic dermatitis with Runfuzhiyang powder: combined RNA-seq, bioinformatics analysis, and experimental research

Background

Atopic dermatitis (AD) is inflammatory disease. So far, therapeutic mechanism of Runfuzhiyang powder on AD remains to be studied. This study aimed to mine key biomarkers to explore potential molecular mechanism for AD incidence and Runfuzhiyang powder treatment.

Methods

The control group, AD group, treat group (AD mice treated with Runfuzhiyang powder were utilized for studying. Differentially expressed AD-related genes were acquired by intersecting of key module genes related to control group, AD group and treatment group which were screened by WGCNA and AD-related differentially expressed genes (DEGs). KEGG and GO analyses were further carried out. Next, LASSO regression analysis was utilized to screen feature genes. The ROC curves were applied to validate the diagnostic ability of feature genes to obtain AD-related biomarkers. Then protein-protein interaction (PPI) network, immune infiltration analysis and single-gene gene set enrichment analysis (GSEA) were presented. Finally, TF-mRNA-lncRNA and drug-gene networks of biomarkers were constructed.

Results

4 AD-related biomarkers (Ddit4, Sbf2, Senp8 and Zfp777) were identified in AD groups compared with control group and treat group by LASSO regression analysis. The ROC curves revealed that four biomarkers had good distinguishing ability between AD group and control group, as well as AD group and treatment group. Next, GSEA revealed that pathways of E2F targets, KRAS signaling up and inflammatory response were associated with 4 biomarkers. Then, we found that Ddit4, Sbf2 and Zfp777 were significantly positively correlated with M0 Macrophage, and were significantly negatively relevant to Resting NK. Senp8 was the opposite. Finally, a TF-mRNA-lncRNA network including 200 nodes and 592 edges was generated, and 20 drugs targeting SENP8 were predicted.

Conclusion

4 AD-related and Runfuzhiyang powder treatment-related biomarkers (Ddit4, Sbf2, Senp8 and Zfp777) were identified, which could provide a new idea for targeted treatment and diagnosis of AD.

Single-cell analysis of CD4+ tissue residency memory cells (TRMs) in adult atopic dermatitis: A new potential mechanism

The pathophysiology of atopic dermatitis (AD) is complex. CD4+ T cells play an essential role in the development of lesions in AD. However, the underlying mechanism remains unclear. In the present study, we investigated the differentially expressed genes (DEGs) between adult AD lesioned and non-lesioned skin using two datasets from the Gene Expression Omnibus (GEO) database. 62 DEGs were shown to be related to cytokine response. Compared to non-lesioned skin, lesioned skin showed immune infiltration with increased numbers of activated natural killer (NK) cells and CD4+ T memory cells (p < 0.01). We then identified 13 hub genes with a strong association with CD4+ T cells using weighted correlation network analysis. Single-cell analysis of AD detected a novel CD4+ T subcluster, CD4+ tissue residency memory cells (TRMs), which were verified through immunohistochemistry (IHC) to be increased in the dermal area of AD. The significant relationship between CD4+ TRM and AD was assessed through further analyses. FOXO1 and SBNO2, two of the 13 hub genes, were characteristically expressed in the CD4+ TRM, but down-regulated in IFN-γ/TNF-α-induced HaCaT cells, as shown using quantitative polymerase chain reaction (qPCR). Moreover, SBNO2 expression was associated with increased Th1 infiltration in AD (p < 0.05). In addition, genes filtered using Mendelian randomization were positively correlated with CD4+ TRM and were highly expressed in IFN-γ/TNF-α-induced HaCaT cells, as determined using qPCR and western blotting. Collectively, our results revealed that the newly identified CD4+ TRM may be involved in the pathogenesis of adult AD.

IL-26 Potentiates Type 2 Skin Inflammation in the Presence of IL-1β

Atopic dermatitis (AD) is a debilitating inflammatory skin disorder. Biologics targeting the IL-4/IL-13 axis are effective in AD, but there is still a large proportion of patients who do not respond to IL-4R blockade. Further exploration of potentially pathogenic T-cell-derived cytokines in AD may lead to new effective treatments. This study aimed to investigate the downstream effects of IL-26 on skin in the context of type 2 skin inflammation. We found that IL-26 alone exhibited limited inflammatory activity in the skin. However, in the presence of IL-1β, IL-26 potentiated the secretion of TSLP, CXCL1, and CCL20 from human epidermis through Jak/signal transducer and activator of transcription signaling. Moreover, in an in vivo AD-like skin inflammation model, IL-26 exacerbated skin pathology and locally increased type 2 cytokines, most notably of IL13 in skin T helper cells. Neutralization of IL-1β abrogated IL-26-mediated effects, indicating that the presence of IL-1β is required for full IL-26 downstream action in vivo. These findings suggest that the presence of IL-1β enables IL-26 to be a key amplifier of inflammation in the skin. As such, IL-26 may contribute to the development and pathogenesis of inflammatory skin disorders such as AD.

Single-Cell RNA Sequencing Reveals Dysregulated POSTN+WNT5A+ Fibroblast Subclusters in Prurigo Nodularis

Prurigo nodularis (PN) is an intensely pruritic, inflammatory skin disease with a poorly understood pathogenesis. We performed single-cell transcriptomic profiling of 28,695 lesional and nonlesional PN cells. Lesional PN has increased dysregulated fibroblasts (FBs) and myofibroblasts. FBs in lesional PN were shifted toward a cancer-associated FB-like phenotype, with POSTN+WNT5A+ cancer-associated FBs increased in PN and similarly so in squamous cell carcinoma. A multicenter cohort study revealed an increased risk of squamous cell carcinoma and cancer-associated FB-associated malignancies (breast and colorectal) in patients with PN. Systemic fibroproliferative diseases (renal sclerosis and idiopathic pulmonary fibrosis) were upregulated in patients with PN. Ligand-receptor analyses demonstrated an FB neuronal axis with FB-derived WNT5A and periostin interactions with neuronal receptors melanoma cell adhesion molecule and ITGAV. These findings identify a pathogenic and targetable POSTN+WNT5A+ FB subpopulation that may predispose cancer-associated FB-associated malignancies in patients with PN.

Single-cell sequencing reveals distinct immune cell features in cutaneous lesions of pemphigus vulgaris and bullous pemphigoid

Bullous pemphigoid (BP) and pemphigus vulgaris (PV) are two common subtypes of autoimmune bullous disease (AIBD). The key role of circulating autoreactive immune cells contributing to skin damage of AIBD has been widely recognized. Nevertheless, the immune characteristics in cutaneous lesions remain unclear. Here, we performed single-cell RNA sequencing (scRNA-seq) and single-cell VDJ sequencing (scRNA-seq) to generate transcriptional profiles for cells and T/B cell clonetype in skin lesions of BP and PV. We found that the proportions of NK&T, macrophages/ dendritic cells, B cells, and mast cells increased in BP and PV lesions. Then, BP and PV cells constituted over 75% of all myeloid cell subtypes, CD4+ T cell subtypes and CD8+ T cell subtypes. Strikingly, CD8+ Trm was identified to be expanded in PV, and located in the intermediate state of the pseudotime trajectory from CD8+ Tm to CD8+ Tem. Interestingly, CD8+ Tem and CD4+ Treg highly expressed exhaustion-related genes, especially in BP lesions. Moreover, the enhanced cell communication between stromal cells and immune cells like B cells and macrophages/ dendritic cells was also identified in BP and PV lesions. Finally, clone expansion was observed in T cells of BP and PV compared with HC, while CD8+ Trm represented the highest ratio of hyperexpanded TCR clones among all T cell subtypes. Our study generally depicts a large and comprehensive single-cell landscape of cutaneous lesions and highlights immune cell features in BP and PV. This offers potential research targets for further investigation.

Senescent fibroblasts and innate immune cell activation might play a role in the pathogenesis of elderly atopic dermatitis

BACKGROUND

Elderly atopic dermatitis (AD) is a subtype of AD defined by age (≥ 60 years). The molecular characteristics of elderly AD remain to be clarified.

OBJECTIVE

We sought to characterize the molecular features of skin lesions and peripheral blood mononuclear cells (PBMCs) in patients with AD across different age, focusing on elderly AD.

METHODS

Skin and PBMCs samples were used for RNA sequencing. Analysis of differentially expressed genes and gene set variation analysis were performed. Immunofluorescence staining, quantitative real-time PCR (qRT-PCR), flow cytometry and transwell assay were used for validation.

RESULTS

Compared with healthy controls, the skin transcriptome of AD patients showed common signatures of AD, like barrier dysfunction and enhanced Th1/Th2/Th17 immune pathways. In PBMCs, the expression of Th1/Th2 response genes was more remarkable in adult AD, while expression of Th17-related genes was significantly higher in childhood AD. The gene modules associated with natural killer (NK) cells were downregulated in elderly AD. In skin lesions, elderly AD exhibited enrichment of macrophages, fibroblasts and senescence-associated secretory phenotype (SASP) related genes. The correlation among fibroblasts, SASP and innate immune cells were revealed by the co-localization of fibroblasts, macrophages and NK cells in the lesions across different age groups. Fibroblasts under inflammation or senescence could induce stronger chemotaxis of macrophages and NK cells.

CONCLUSION

We identified the molecular phenotypes of skin lesions and PBMCs in elderly AD individuals. Fibroblasts, innate immune cells, and SASP might play important roles in the pathogenesis of elderly AD.

Immunobiology of IL-26

T helper 17 (Th17) cells produce a set of cytokines that include IL-17 family members, IL-21, IL-22, and IL-26. These cytokines all contribute to the classic function of Th17 cells in combatting extracellular infection and promoting inflammation in autoimmune diseases. However, of the Th17 cytokines, only IL-26 has direct antimicrobial activity against microbes and can activate a broad range of immune cells through its ability to bind DNA and trigger pattern recognition receptors. It is noteworthy that IL-26 is produced by mammalian cells, including human Th17 cells, but is absent in rodents. As such, IL-26 is a potential therapeutic target to augment host immune responses against microbial pathogens but also to prevent inflammation and tissue damage in a variety of autoimmune diseases.

Screening mitochondria-related biomarkers in skin and plasma of atopic dermatitis patients by bioinformatics analysis and machine learning

Background

There is a significant imbalance of mitochondrial activity and oxidative stress (OS) status in patients with atopic dermatitis (AD). This study aims to screen skin and peripheral mitochondria-related biomarkers, providing insights into the underlying mechanisms of mitochondrial dysfunction in AD.

Methods

Public data were obtained from MitoCarta 3.0 and GEO database. We screened mitochondria-related differentially expressed genes (MitoDEGs) using R language and then performed GO and KEGG pathway analysis on MitoDEGs. PPI and machine learning algorithms were also used to select hub MitoDEGs. Meanwhile, the expression of hub MitoDEGs in clinical samples were verified. Using ROC curve analysis, the diagnostic performance of risk model constructed from these hub MitoDEGs was evaluated in the training and validation sets. Further computer-aided algorithm analyses included gene set enrichment analysis (GSEA), immune infiltration and mitochondrial metabolism, centered on these hub MitoDEGs. We also used real-time PCR and Spearman method to evaluate the relationship between plasma circulating cell-free mitochondrial DNA (ccf-mtDNA) levels and disease severity in AD patients.

Results

MitoDEGs in AD were significantly enriched in pathways involved in mitochondrial respiration, mitochondrial metabolism, and mitochondrial membrane transport. Four hub genes (BAX, IDH3A, MRPS6, and GPT2) were selected to take part in the creation of a novel mitochondrial-based risk model for AD prediction. The risk score demonstrated excellent diagnostic performance in both the training cohort (AUC = 1.000) and the validation cohort (AUC = 0.810). Four hub MitoDEGs were also clearly associated with the innate immune cells' infiltration and the molecular modifications of mitochondrial hypermetabolism in AD. We further discovered that AD patients had considerably greater plasma ccf-mtDNA levels than controls (U = 92.0, p< 0.001). Besides, there was a significant relationship between the up-regulation of plasma mtDNA and the severity of AD symptoms.

Conclusions

The study highlights BAX, IDH3A, MRPS6 and GPT2 as crucial MitoDEGs and demonstrates their efficiency in identifying AD. Moderate to severe AD is associated with increased markers of mitochondrial damage and cellular stress (ccf=mtDNA). Our study provides data support for the variation in mitochondria-related functional characteristics of AD patients.

Single-cell RNA sequencing reveals 2D cytokine assay can model atopic dermatitis more accurately than immune-competent 3D setup

Modelling atopic dermatitis (AD) in vitro is paramount to understand the disease pathophysiology and identify novel treatments. Previous studies have shown that the Th2 cytokines IL-4 and IL-13 induce AD-like features in keratinocytes in vitro. However, it has not been systematically researched whether the addition of Th2 cells, their supernatants or a 3D structure is superior to model AD compared to simple 2D cell culture with cytokines. For the first time, we investigated what in vitro option most closely resembles the disease in vivo based on single-cell RNA sequencing data (scRNA-seq) obtained from skin biopsies in a clinical study and published datasets of healthy and AD donors. In vitro models were generated with primary fibroblasts and keratinocytes, subjected to cytokine treatment or Th2 cell cocultures in 2D/3D. Gene expression changes were assessed using qPCR and Multiplex Immunoassays. Of all cytokines tested, incubation of keratinocytes and fibroblasts with IL-4 and IL-13 induced the closest in vivo-like AD phenotype which was observed in the scRNA-seq data. Addition of Th2 cells to fibroblasts failed to model AD due to the downregulation of ECM-associated genes such as POSTN. While keratinocytes cultured in 3D showed better stratification than in 2D, changes induced with AD triggers did not better resemble AD keratinocyte subtypes observed in vivo. Taken together, our comprehensive study shows that the simple model using IL-4 or IL-13 in 2D most accurately models AD in fibroblasts and keratinocytes in vitro, which may aid the discovery of novel treatment options.

Proteomic alterations in patients with atopic dermatitis

INTRODUCTION

Atopic Dermatitis (AD) is the most common inflammatory skin disease with a complex and multifactorial pathogenesis. The use of proteomics in understanding AD has yielded the discovery of novel biomarkers and may further expand therapeutic options.

AREAS COVERED

This review summarizes the most recent proteomic studies and the methodologies used in AD. It describes novel biomarkers that may monitor disease course and therapeutic response. The review also highlights skin and blood biomarkers characterizing different AD phenotypes and differentiates AD from other inflammatory skin disorders. A literature search was conducted by querying Scopus, Google Scholar, Pubmed/Medline, and Clinicaltrials.gov up to June 2023.

EXPERT OPINION

The integration of proteomics into research efforts in atopic dermatitis has broadened our understanding of the molecular profile of AD through the discovery of new biomarkers. In addition, proteomics may contribute to the development of targeted treatments ultimately improving personalized medicine. An increasing number of studies are utilizing proteomics to explore this heterogeneous disease.

Patient-reported assessment of medical care for chronic inflammatory skin diseases: an enterprise-based survey

Background

Chronic inflammatory skin diseases (CISDs) are among the most common diseases in the Western world. Current estimates of medical care for CISDs are primarily based on surveys among patients in medical care facilities and on health insurance data.

Aim

Survey-based examination to what extent CISD patients in health-aware environment consider their skin disease to be controlled.

Methods

The survey of CISD patients was carried out in 2022 among the employees of a pharmaceutical company located in Germany and Switzerland. Software-based, anonymous, self-reported questionnaires were used.

Results

The number of employees, who answered the questionnaire, was 905. Of these, 222 participants (24.5%) reported having at least one CISD. 28.7% of participants with CISD described their disease as being hardly or not controlled. Regarding the nature of disease, more than one third of participants suffering from hidradenitis suppurativa (HS) or psoriasis fell into the hardly/not controlled category. In contrast, the largest proportion of participants with chronic spontaneous urticaria (43%) or atopic dermatitis (42%) considered their CISD to be completely or well controlled. Only 35.5% of CISD sufferers stated that they were currently under medical care for their skin condition. Being under medical care, however, had no influence on the extent CISD sufferers considered their skin disease to be controlled. The number of active CISD episodes but not the total number of symptomatic days per year was negatively associated with poor disease control (p = 0.042 and p = 0.856, respectively). Poor disease control had a negative effect on the personal and professional lives of those affected, as deduced from its positive association with the extent of daily activity impairment and presenteeism (p = 0.005 and p = 0.005, respectively). Moreover, 41.4 and 20.7% of participants with hardly/not controlled disease stated that their CISD had a moderate and severe or very severe impact on their overall lives (p < 0.001), respectively. A severe or very severe impact of their CISD on their overall life was most commonly reported by participants with HS.

Conclusion

Medical care for CISDs, even in an environment with high socio-economic standard and high health-awareness, still appears to be limited and has a negative impact on individuals and society.

LIGHT signaling through LTβR and HVEM in keratinocytes promotes psoriasis and atopic dermatitis-like skin inflammation

Psoriasis (PS) and atopic dermatitis (AD) are common skin inflammatory diseases characterized by hyper-responsive keratinocytes. Although, some cytokines have been suggested to be specific for each disease, other cytokines might be central to both diseases. Here, we show that Tumor necrosis factor superfamily member 14 (TNFSF14), known as LIGHT, is required for experimental PS, similar to its requirement in experimental AD. Mice devoid of LIGHT, or deletion of either of its receptors, lymphotoxin β receptor (LTβR) and herpesvirus entry mediator (HVEM), in keratinocytes, were protected from developing imiquimod-induced psoriatic features, including epidermal thickening and hyperplasia, and expression of PS-related genes. Correspondingly, in single cell RNA-seq analysis of PS patient biopsies, LTβR transcripts were found strongly expressed with HVEM in keratinocytes, and LIGHT was upregulated in T cells. Similar transcript expression profiles were also seen in AD biopsies, and LTβR deletion in keratinocytes also protected mice from allergen-induced AD features. Moreover, in vitro, LIGHT upregulated a broad spectrum of genes in human keratinocytes that are clinical features of both PS and AD skin lesions. Our data suggest that agents blocking LIGHT activity might be useful for therapeutic intervention in PS as well as in AD.

JAK1/JAK2 degraders based on PROTAC for topical treatment of atopic dermatitis

Atopic dermatitis (AD) is a prevalent chronic inflammatory skin disease. The Janus kinase (JAK) has been identified as a target in AD, as it regulates specific inflammatory genes and adaptive immune responses. However, the efficacy of topically applied JAK inhibitors in AD is limited due to the unique structure of skin. We synthesized JAK1/JAK2 degraders (JAPT) based on protein degradation targeting chimeras (PROTACs) and prepared them into topical preparations. JAPT exploited the E3 ligase to mediate ubiquitination and degradation of JAK1/JAK2, offering a promising AD therapeutic approach with low frequency and dosage. In vitro investigations demonstrated that JAPT effectively inhibited the release of pro-inflammatory cytokines and reduced inflammation by promoting the degradation of JAK. In vivo studies further confirmed the efficacy of JAPT in degrading JAK1/JAK2, leading to a significant suppression of type I, II, and III adaptive immunity. Additionally, JAPT demonstrated a remarkable reduction in AD severity, as evidenced by improved skin lesion clearance and AD severity scores (SCORAD). Our study revealed the therapeutic potential of JAPT, surpassing conventional JAK inhibitors in the treatment of AD, which suggested that JAPT could be a promising topically applied anti-AD drug targeting the JAK-STAT signaling pathway.

Association of different cell types and inflammation in early acne vulgaris

Acne vulgaris, one of the most common skin diseases, is a chronic cutaneous inflammation of the upper pilosebaceous unit (PSU) with complex pathogenesis. Inflammation plays a central role in the pathogenesis of acne vulgaris. During the inflammatory process, the innate and adaptive immune systems are coordinately activated to induce immune responses. Understanding the infiltration and cytokine secretion of differential cells in acne lesions, especially in the early stages of inflammation, will provide an insight into the pathogenesis of acne. The purpose of this review is to synthesize the association of different cell types with inflammation in early acne vulgaris and provide a comprehensive understanding of skin inflammation and immune responses.

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

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

KRT6A Inhibits IL-1β-Mediated Pyroptosis of Keratinocytes via Blocking IL-17 Signaling

Keratin 6A (KRT6A) is involved in the pathogenesis of various skin diseases. However, the reports on the roles of KRT6A in atopic dermatitis (AD) are limited. This study aimed to investigate the potentials of KRT6A in AD. mRNA levels were detected by RT-PCR. Cytokine release was determined by ELISA. Protein expression was determined using Western blot. Cell viability was determined by CCK-8. Cytotoxicity was detected by LDH assay. Cell death was determined by TUNEL. The pyroptosis of keratinocytes was detected using flow cytometry. We found that KRT6A was overexpressed in AD patients. Moreover, KRT6A was stimulated after exposed to proinflammatory cytokines. Overexpressed KRT6A suppressed inflammatory response, while KRT6A knockdown exerted the opposite effects. Overexpressed KRT6A suppressed inflammation-induced pyroptosis of keratinocytes. Additionally, KRT6A negatively regulated interleukin-17a (IL-17a) expression, blocking IL-17 signaling. IL-17a overexpression antagonized the effects of KRT6A and promoted pyroptosis of keratinocytes. In conclusion, KRT6A exerted protective functions in AD via regulating IL-17 signaling. This KRT6A/IL-17 may be a novel target for AD.

Matching-Adjusted Indirect Comparison of the Long-Term Efficacy Maintenance and Adverse Event Rates of Lebrikizumab versus Dupilumab in Moderate-to-Severe Atopic Dermatitis

INTRODUCTION

Lebrikizumab and dupilumab are monoclonal antibodies approved for treating moderate-to-severe atopic dermatitis (AD). Both have demonstrated efficacy and safety over the 16-week SOLOs and ADvocate trials. However, AD is a chronic and relapsing inflammatory disease, and the long-term maintenance of efficacy is critical for achieving disease control from the perspective of patients, physicians, and regulatory agencies. This study aims to compare the long-term efficacy and safety of lebrikizumab every 4 weeks (Q4W) and dupilumab every week or every 2 weeks (QW/Q2W) among adult patients who have achieved treatment efficacy following the induction period of 16 weeks.

METHODS

Lebrikizumab's efficacy was assessed using individual patient data (IPD) from the ADvocate 1 and 2 monotherapy trials. Dupilumab's efficacy was evaluated using aggregate data from the adult-exclusive SOLO-CONTINUE trial. Due to the absence of a common comparator trial arm, we employed an unanchored matching-adjusted indirect comparison (MAIC), a robust methodology widely accepted by health technology assessment (HTA) agencies. This re-weights ADvocate IPD to align with SOLO-CONTINUE's prognostic factors and effect modifiers. We compared lebrikizumab's adjusted outcomes with dupilumab outcomes at week 52, focusing on 75% improvement in the Eczema Area and Severity Index from baseline (EASI-75), Investigator's Global Assessment (IGA) score of 0 or 1, and overall adverse event (AE) rates. Sensitivity analyses were conducted to test various combinations of matching variables.

RESULTS

Adults on lebrikizumab Q4W were more likely to maintain IGA 0/1 through the 36-week maintenance period (weeks 16-52) compared with those on dupilumab QW/Q2W [risk ratio (RR) 1.334; 95% confidence interval (CI) 1.02-1.74; p = 0.035]. Both treatments demonstrated comparable efficacy in terms of EASI-75 maintenance (RR 0.937; 95% CI 0.78-1.13; p = 0.490) and similar AE rates (RR 1.052; 95% CI 0.90-1.23; p = 0.526). Sensitivity analyses substantiated these findings.

CONCLUSIONS

Our findings suggest that lebrikizumab Q4W may provide equal or superior long-term maintenance of efficacy measured with EASI-75 and IGA 0/1 compared with dupilumab QW/Q2W, with the advantage of requiring less frequent doses.

Toward Precision Medicine in Atopic Dermatitis Using Molecular-Based Approaches

Atopic dermatitis is the most common chronic inflammatory skin disorder, affecting up to 20% of children and 10% of adults in developed countries. The pathophysiology of atopic dermatitis is complex and involves a strong genetic predisposition and T-cell driven inflammation. Although our understanding of the pathology and drivers of this disease has improved in recent years, there are still knowledge gaps in the immune pathways involved. Therefore, advances in new omics technologies in atopic dermatitis will play a key role in understanding the pathogenesis of this burden disease and could develop preventive strategies and personalized treatment strategies. In this review, we discuss the latest developments in genetics, transcriptomics, epigenomics, proteomics, and metagenomics and understand how integrating multiple omics datasets will identify potential biomarkers and uncover nets of associations between several molecular levels.

Toward Precision Medicine in Atopic Dermatitis Using Molecular-Based Approaches

Atopic dermatitis is the most common chronic inflammatory skin disorder, affecting up to 20% of children and 10% of adults in developed countries. The pathophysiology of atopic dermatitis is complex and involves a strong genetic predisposition and T-cell driven inflammation. Although our understanding of the pathology and drivers of this disease has improved in recent years, there are still knowledge gaps in the immune pathways involved. Therefore, advances in new omics technologies in atopic dermatitis will play a key role in understanding the pathogenesis of this burden disease and could develop preventive strategies and personalized treatment strategies. In this review, we discuss the latest developments in genetics, transcriptomics, epigenomics, proteomics, and metagenomics and understand how integrating multiple omics datasets will identify potential biomarkers and uncover nets of associations between several molecular levels.

CD163 as a Potential Biomarker-associated Immune Inflammation in Diabetes Mellitus: A Systematic Review and Bioinformatics Analysis

BACKGROUND

Several studies have identified CD163 as a potential mediator of diabetes mellitus through an immune-inflammation. Further study is necessary to identify its specific mechanism.

OBJECTIVES

In this study, we aimed to investigate CD163 as a potential biomarker associated with immune inflammation in diabetes mellitus through a systematic review and bioinformatics analysis.

METHODS

We searched PubMed, Web of Science, the Cochrane Library, and Embase databases with a time limit of September 2, 2022. Furthermore, we conducted a systematic search and review based on PRISMA guidelines. Additionally, diabetic gene expression microarray datasets GSE29221, GSE30528, GSE30529, and GSE20966 were downloaded from the GEO database (http://www.ncbi.nlm.nih.gov/geo) for bioinformatics analysis. The PROSPERO number for this study is CRD420222347160.

RESULTS

Following the inclusion and exclusion criteria, seven articles included 1607 patients, comprising 912 diabetic patients and 695 non-diabetic patients. This systematic review found significantly higher levels of CD163 in diabetic patients compared to non-diabetic patients. People with diabetes had higher levels of CRP expression compared to the control group. Similarly, two of the three papers that used TNF- α as an outcome indicator showed higher expression levels in diabetic patients. Furthermore, IL-6 expression levels were higher in diabetic patients than in the control group. A total of 62 samples were analyzed by bioinformatics (33 case controls and 29 experimental groups), and 85 differential genes were identified containing CD163. According to the immune cell correlation analysis, CD163 was associated with macrophage M2, γδ T lymphocytes, macrophage M1, and other immune cells. Furthermore, to evaluate the diagnostic performance of CD163, we validated it using the GSE20966 dataset. In the validation set, CD163 showed high diagnostic accuracy.

CONCLUSION

This study suggests CD163 participates in the inflammatory immune response associated with diabetes mellitus and its complications by involving several immune cells. Furthermore, the results suggest CD163 may be a potential biomarker reflecting immune inflammation in diabetic mellitus.

Macrophage autophagy deficiency-induced CEBPB accumulation alleviates atopic dermatitis via impairing M2 polarization

Macroautophagy/autophagy plays a pivotal role in immune regulation. Its significance is evident in modulation of immune cell differentiation and maturation, physiologically and pathologically. Here, we investigate the role of macrophage autophagy on the development of atopic dermatitis (AD). By employing an MC903-induced AD mice model, we observe reduced cutaneous inflammation in macrophage Atg5 cKO mice compared with WT mice. Notably, there is a decreased infiltration of M2 macrophages in lesional skin from Atg5 cKO mice. Furthermore, impaired STAT6 phosphorylation and diminished expression of M2 markers are detected in autophagy-deficient macrophages. Our mechanistic exploration reveals that CEBPB drives the transcription of SOCS1/3 and SQSTM1/p62-mediated autophagy degrades CEBPB normally. Autophagy deficiency leads to CEBPB accumulation, and further promotes the expression of SOCS1/3. This process inhibits JAK1-STAT6 pathway activation and M2 marker expression. Together, our study indicates that autophagy is required for M2 activation and macrophage autophagy may be a promising target for AD intervention.

Identifying characteristics of dermal fibroblasts in skin homeostasis and disease

Heterogeneous dermal fibroblasts are the main components that constitute the dermis. Distinct fibroblast subgroups show specific characteristics and functional plasticity that determine dermal structure during skin development and wound healing. Although researchers have described the roles of fibroblast subsets, this is not completely understood. We review recent evidence supporting understanding about the heterogeneity of fibroblasts. We summarize the origins and the identified profiles of fibroblast subpopulations. The characteristics of fibroblast subpopulations in both healthy and diseased states are highlighted, and the potential of subpopulations to be involved in wound healing in different ways was discussed. Additionally, we review the plasticity of subpopulations and the underlying signalling mechanisms. This review may provide greater insights into potential novel therapeutic targets and tissue regeneration strategies for the future.

Single-cell RNA-seq reveals abnormal differentiation of keratinocytes and increased inflammatory differentiated keratinocytes in atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is a chronic and recurrent inflammatory skin disease characterized by severe pruritus and eczematous lesions. Heterogeneity of AD has been reported among different racial groups according to clinical, molecular and genetic differences.

OBJECTIVE

This study aimed to conduct an in-depth transcriptome analysis of AD in Chinese population.

METHODS

We performed single-cell RNA sequencing (scRNA-seq) analysis of skin biopsies from five Chinese adult patients with chronic AD and from four healthy controls, combined with multiplexed immunohistochemical analysis in whole-tissue skin biopsies. We explored the functions of IL19 in vitro.

RESULTS

ScRNA-seq analysis was able to profile a total of 87,853 cells, with keratinocytes (KCs) in AD manifesting highly expressed keratinocyte activation and pro-inflammatory genes. KCs demonstrated a novel IL19+ IGFL1+ subpopulation that increased in AD lesions. Inflammatory cytokines IFNG, IL13, IL26 and IL22 were highly expressed in AD lesions. In vitro, IL19 directly downregulated KRT10 and LOR in HaCaT cells and activated HaCaT cells to produce TSLP.

CONCLUSION

Abnormal proliferation and differentiation of keratinocytes contribute immensely to the pathogenesis of AD, whereas AD chronic lesions have witnessed significant presence of IL19+ IGFL1+ KCs, which may be involved in the disruption of the skin barrier, the connection and magnification of Th2 and Th17 inflammatory responses, and mediation of skin pruritus. Furthermore, progressive activation of multiple immune axes dominated by Type 2 inflammatory reaction occur in AD chronic lesions.