Classification of human chronic inflammatory skin disease based on single-cell immune profiling

Inhibition of CTSC contributes to psoriasis inflammation and keratinocyte hyperproliferation by NF-κB signaling pathway

It was found that mutations in the Cathepsin C (CTSC) gene are responsible for Papillon-Lefevre syndrome which has a characteristic clinical feature of palmoplantar hyperkeratosis and psoriasiform lesions. However, its function in psoriasis is unclear so far. This study aims to investigate the roles and mechanisms of CTSC in psoriasis. The expression of CTSC was investigated by the analysis of single cell RNA sequencing (scRNA-seq) data and skin lesions of psoriasis patients. The role of CTSC in psoriasis was analyzed in human immortalized keratinocytes (HaCaT) stimulated with different inflammatory factors and mice of imiquimod (IMQ)-induced psoriasiform dermatitis. We showed that the expression of CTSC was significantly increased in the analysis of scRNA-seq data, which was identified in skin lesions of psoriasis patients and IMQ-induced psoriasis-like mice, and primary human keratinocytes and HaCaT cells stimulated with a cocktail of cytokines. In the presence of inflammatory factors or IMQ, CTSC inhibitor and knockdown of CTSC using siRNA exhibited significantly increased keratinocytes proliferation and the levels of proinflammatory cytokines. In vitro and in vivo experiments further showed that inhibited CTSC in psoriasis could activate the pathway of nuclear factor-κB (NF-κB). This study firstly outlines that inhibition of CTSC can contribute to inflammation and keratinocyte hyperproliferation by NF-κB pathway in psoriasis. It may provide a new perspective on understanding of the pathogenesis of psoriasis.

Psoriasis harbors multiple pathogenic type 17 T-cell subsets: Selective modulation by risankizumab

BACKGROUND

Recent single-cell studies indicated that IL-17-producing T cells (T17) have diverse subsets expressing IL-17A, IL-17F, or a combination in human psoriasis skin. However, it is unknown how T17 subsets are differently regulated by IL-23 versus IL-17A blockade.

OBJECTIVE

We sought to investigate how systemic monoclonal antibody injections blocking IL-23 versus IL-17A differently modify immune cell transcriptomes in human psoriasis skin.

METHODS

We analyzed a total of 93 human skin single-cell libraries, including 42 psoriasis pretreatment lesional skin, 25 psoriasis pretreatment nonlesional skin, 12 psoriasis posttreatment after IL-23 inhibition, 4 psoriasis posttreatment after IL-17A inhibition, and 10 control skin samples.

CLINICALTRIALS

gov NCT04630652.

RESULTS

Of the six T17 subsets identified, an IL17A+IFNG+ subset and an IL17F+IL10- subset expressed the IL-23 receptor along with other inflammatory cytokines, and IL-23 inhibition downregulated these potentially pathogenic T17 subsets. In contrast, T17 cells expressing both IL-17A and IL-17F did not express the IL-23 receptor, and the percentage of this potentially nonpathogenic T17 subset increased after IL-23 inhibition. In addition, the expression of the IL-17-negative regulation genes, such as TNFAIP3, increased in myeloid cells more after IL-23 inhibition than after IL-17A inhibition.

CONCLUSIONS

This study suggests multiple immune mechanisms of how IL-23 inhibition can modify the complex inflammatory environment present in psoriatic skin, highlighting the roles of specific T17 subsets in psoriasis development and background skin protection.

The spatial and single-cell landscape of skin: Charting the multiscale regulation of skin immune function

Immune regulation is a key function of the skin, a barrier tissue that exhibits spatial compartmentalization of innate and adaptive immune cells. Recent advances in single-cell RNA sequencing (scRNA-seq) and spatial transcriptomics (ST) have facilitated systems-based investigations into the molecular and cellular features of skin immunity at single-cell resolution, identifying cell types that maintain homeostasis in a coordinated manner, and those that exhibit dysfunctional cell-cell interactions in disease. Here, we review how technological innovation is uncovering the multiple scales of heterogeneity in the immune landscape of the skin. The microanatomic scale encompasses the skin's diverse cellular components and multicellular spatial organization, which govern the functional cell interactions and behaviors necessary to protect the host. On the macroanatomic scale, understanding heterogeneity in cutaneous tissue architecture across anatomical sites promises to unearth additional functional immune variation and resulting disease consequences. We focus on how single-cell and spatial dissection of the immune system in experimental models and in humans has led to a deeper understanding of how each cell type in the skin contributes to overall immune function in a context-dependent manner. Finally, we highlight translational opportunities for adopting these technologies, and insights gleaned from them, into the clinic.

Tissue-resident memory T cells and their function in skin diseases

ABSTRACT

Tissue-resident memory T (TRM) cells are a recently defined subtype of non-recirculating memory T cells with longevity and protective functions in peripheral tissues. As an essential frontline defense against infections, TRM cells have been reported to robustly patrol the tissue microenvironment in malignancies. Accumulating evidence also implicates that TRM cells in the relapse of chronic inflammatory skin diseases such as psoriasis and vitiligo. In light of these developments, this review aims to synthesize these recent findings to enhance our understanding of TRM cell characteristics and actions. Therefore, after providing a brief overview of the general features of the TRM cells, including precursors, homing, retention, and maintenance, we discuss recent insights gained into their heterogeneous functions in skin diseases. Specifically, we explore their involvement in conditions such as psoriasis, vitiligo, fixed drug eruption - dermatological manifestations of drug reactions at the same spot, cutaneous T cell lymphoma, and melanoma. By integrating these diverse perspectives, this review develops a comprehensive model of TRM cell behavior in various skin-related pathologies. In conclusion, our review emphasizes that deciphering the characteristics and mechanisms of TRM cell actions holds potential not only for discovering methods to slow cancer growth but also for reducing the frequency of recurrent chronic inflammation in skin tissue.

Bimetallic Plasmonic Nanozyme-Based Microneedle for Synergistic Ferroptosis Therapy of Melanoma

Melanoma is the most common malignant skin tumor, characterized by complexity, invasiveness, and heterogeneity. Conventional therapies often yield poor outcomes, posing significant clinical challenges. Here, a microneedle (MN) patch that integrates nanozyme and traditional Chinese medicine (TCM) for ferroptosis pathway-dependent combined therapy of melanoma is designed. To amplify therapeutic activity, a novel Au@MoS2 bimetallic plasmonic nanozyme (BPNzyme) is prepared through a simple aqueous synthesis strategy involving a two-step process. Owing to the synergy between heterostructures, this rationally designed BPNzyme exhibits significantly enhanced therapeutic characteristics, including near-infrared (NIR) photothermal effect, peroxidase-like activity, and glutathione peroxidase-like property, which can effectively reshape the tumor microenvironment and disrupt the redox homeostasis. Under the combined action of the TCM β-elemene (β-ELE) and NIR light, further enhancement of oxidative damage, lipid peroxidation, and glutathione peroxidase 4 expression downregulation are observed for skin tumor cells, validating the synergistic amplification of ferroptosis. Moreover, the transdermal delivery of BPNzyme and β-ELE using the soluble hyaluronic acid MN patch effectively achieves 99.8% tumor growth suppression without significant systemic toxicity in vivo. These findings highlight the potential of the rationally designed BPNzyme-based MN system as a promising innovative strategy for non-invasive, efficient, and safe combination therapy of melanoma.

Detection by Single-Cell RNA Sequencing of Virally Mediated Skin Diseases

Viruses are well-documented agents of specific skin diseases. However, their role and precise mechanism of action in other skin diseases remain unknown. We describe a single-cell RNA-sequencing-based strategy to interrogate human skin biopsies for viral transcripts, permitting detection of viral infection within a sample, single-cell resolution of virally infected cells and identification of subsequent transcriptomic perturbations. We validate our pipeline with 100% sensitivity and specificity by (i) detecting Merkel cell polyomavirus in Merkel cell carcinoma samples, (ii) detecting specific human papillomavirus strains in known human papillomavirus-positive tumors, and (iii) detecting rubella virus transcripts in patients with known rubella-associated granulomas. We identify infection of known and previously unreported cell types and elucidate viral-mediated transcriptional perturbations. In rubella virus-infected cells, we discover macrophage-specific evolution of the rubella virus E1 capsid protein. Finally, we interrogate skin biopsies from many established nonvirally mediated inflammatory skin diseases and do not find consistent evidence of viral infection in any condition. Combining single-cell RNA-sequencing data with virome detection strategies represents a potentially powerful approach to investigate and elucidate virus-mediated gene regulation in health and disease.

Advances and applications in single-cell and spatial genomics

The applications of single-cell and spatial technologies in recent times have revolutionized the present understanding of cellular states and the cellular heterogeneity inherent in complex biological systems. These advancements offer unprecedented resolution in the examination of the functional genomics of individual cells and their spatial context within tissues. In this review, we have comprehensively discussed the historical development and recent progress in the field of single-cell and spatial genomics. We have reviewed the breakthroughs in single-cell multi-omics technologies, spatial genomics methods, and the computational strategies employed toward the analyses of single-cell atlas data. Furthermore, we have highlighted the advances made in constructing cellular atlases and their clinical applications, particularly in the context of disease. Finally, we have discussed the emerging trends, challenges, and opportunities in this rapidly evolving field.

Mendelian Randomization Combined with Single-Cell Transcriptome Analysis Reveals the Role of the Key Gene PCLAF in the Pathogenesis of Atopic Dermatitis

Background

Atopic dermatitis (AD) is a chronic inflammatory skin condition characterized by itching and rashes, influenced by genetic, environmental, and immune factors. Despite significant research, the molecular mechanisms underlying AD are not fully understood. This study aims to integrate single-cell RNA sequencing (scRNA-seq) with Mendelian Randomization (MR) to uncover genetic and metabolic pathways contributing to AD.

Materials and Methods

Data from scRNA-seq and bulk RNA sequencing datasets were analyzed to identify differentially expressed genes. The edgeR package was used for differential expression analysis, and candidate genes were explored using MR, employing eQTL data to determine causal relationships with AD. The inverse variance weighted method facilitated MR analysis, while gene set enrichment analysis (GSEA) was used to identify pathways associated with AD. Single-cell analysis was performed with the Seurat package to explore cellular heterogeneity, and pseudotime and cellular communication analyses were conducted to understand cell differentiation and interactions in AD.

Results

The study identified key genes-PCLAF, MICB, CHAD, and CA4-linked to AD, with PCLAF notably acting as a risk factor. These genes are involved in cell cycle regulation, immune evasion, cell adhesion, and metabolic processes. The MR analysis highlighted lipid, amino acid, and energy metabolism as critical pathways in AD. Single-cell analysis revealed increased cellular communication in AD, especially in Langerhans cells, keratinocytes, and T cells, signifying dysregulated immune responses and inflammatory pathways. Pseudotime analysis indicated abnormal differentiation trajectories in these cell types.

Conclusion

Our study highlights the importance of PCLAF in the pathogenesis of AD, indicating it as a potential target for future therapeutic strategies aimed at alleviating the disease by addressing genetic and metabolic disruptions.

A case of biologic-resistant hand dermatitis demonstrates dual T2/T17 transcriptomic abnormalities and responds to Janus kinase inhibition

Many patients do not respond to targeted pathway-specific biologic therapies but predicting such failure remains an outstanding challenge. Here, in a case of adult-onset hand dermatitis that did not respond to multiple targeted biologic therapies, we detected gene expression programmes activated in both atopic dermatitis and psoriasis, via high-resolution genetic profiling. Broader, kinase-based immunosuppression elicited a near-complete clinical response. Therefore, our data suggest that such cases harbouring greater molecular complexity might be identified prospectively, circumventing some failures of single-pathway blockade.

Investigating the complex roles of immunocyte phenotypes in the pathogenesis of dermatitis: a causal inference Mendelian randomization analysis

The etiology of dermatitis involves complex interactions between immune cells, genetics, and environmental factors. While immunocyte phenotypes have been linked to various forms of dermatitis, their causal role remains unclear. We conducted a two-sample Mendelian randomization (MR) analysis to investigate the causal effects between 731 immunocyte phenotypes and four types of dermatitis: atopic dermatitis, contact dermatitis, infective dermatitis, and seborrhoeic dermatitis. Genetic variants were used as instrumental variables, and the inverse variance-weighted (IVW) method was employed to assess causality. Sensitivity analyses were performed to ensure robustness. The forward MR analysis identified significant associations between 22 immunocyte phenotypes and atopic dermatitis, 8 phenotypes with contact dermatitis, 5 with infective dermatitis, and 6 with seborrhoeic dermatitis. The reverse MR analysis suggested potential bidirectional interactions of atopic dermatitis and CD3 on CD28 + CD45RA- CD8br (OR = 0.924, P = 0.012). This study revealed causal relationships between specific immunocyte phenotypes and dermatitis subtypes, providing novel insights into the immunopathogenesis of dermatitis and potential therapeutic targets.

Senescence as a molecular target in skin aging and disease

Skin aging represents a multifactorial process influenced by both intrinsic and extrinsic factors, collectively known as the skin exposome. Cellular senescence, characterized by stable cell cycle arrest and secretion of pro-inflammatory molecules, has been implicated as a key driver of physiological and pathological skin aging. Increasing evidence points towards the role of senescence in a variety of dermatological diseases, where the accumulation of senescent cells in the epidermis and dermis exacerbates disease progression. Emerging therapeutic strategies such as senolytics and senomorphics offer promising avenues to target senescent cells and mitigate their deleterious effects, providing potential treatments for both skin aging and senescence-associated skin diseases. This review explores the molecular mechanisms of cellular senescence and its role in promoting age-related skin changes and pathologies, while compiling the observed effects of senotherapeutics in the skin and discussing the translational relevance.

Single-cell RNA sequencing in autoimmune diseases: New insights and challenges

Autoimmune diseases involve a variety of cell types, yet the intricacies of their individual roles within molecular mechanisms and therapeutic strategies remain poorly understood. Single-cell RNA sequencing (scRNA-seq) offers detailed insights into transcriptional diversity at the single-cell level, significantly advancing research in autoimmune diseases. This article explores how scRNA-seq enhances the understanding of cellular heterogeneity and its potential applications in the etiology, diagnosis, treatment, and prognosis of autoimmune diseases. By revealing a comprehensive cellular landscape, scRNA-seq illuminates the functional regulation of different cell subtypes during disease progression. It aids in identifying diagnostic and prognostic markers, and analyzing cell communication networks to uncover potential therapeutic targets. Despite its valuable contributions, addressing the limitations of scRNA-seq is essential for making further advancements.

Immunological profile of lactate metabolism-related genes in Psoriasis a comprehensive analysis based on bulk and single-cell RNA sequencing data

Psoriasis (Pso) is a chronic erythema squamous disease often accompanied by metabolic abnormalities. Disturbances in lactate metabolism have been observed in the skin of patients with Pso, but the role of lactate metabolism in the pathogenesis of Pso remains unclear. To identify core genes associated with lactate metabolism in Pso, we downloaded and merged two Pso-related datasets (GSE13355, GSE109248) from the GEO database. Through comprehensive analysis, we analyzed the functions associated with these hub genes and the correlation between their expression levels and immune infiltration. Additionally, we explored lactate metabolism-related hub genes in different immune cells using single-cell sequencing data. We identified four lactate metabolism-related hub genes that are highly associated with Pso. Further analysis revealed that these four hub genes were significantly correlated with the levels of immune cell infiltration. To further elucidate the impact of lactate metabolism on immune cells, we analyzed single-cell sequencing data from healthy controls and Pso patients. The expression of lactate metabolism-related hub genes was primarily observed in moDCs and T cells. These results suggest that lactate metabolism-related genes and their functions are closely associated with changes in inflammatory cells in Pso patients. This study provides new insights into the role of lactate metabolism in the pathogenesis of Pso and highlights potential therapeutic targets for the disease.

Periostin in Bullous Pemphigoid: A Potential Biomarker of Disease Activity and Severity

Elevated periostin levels are commonly observed in conditions characterised by increased IgE and eosinophilia, such as bullous pemphigoid (BP), which typically presents with eosinophil infiltration and elevated IgE levels. To explore the link between periostin levels and key clinical parameters in BP, serum periostin levels were assessed in 55 classic BP patients and 55 healthy controls using ELISA. Upon admission, the BP Disease Area Index (BPDAI) score, autoantibody levels, and peripheral blood immune cells of BP patients were evaluated. The investigation also employed the Olink proteomic platform to analyse circulating proinflammatory biomarkers. The results indicated significantly higher periostin levels in BP patients, showing a strong positive correlation with BPDAI scores, which was more pronounced compared to the correlation between BPDAI scores and BP 180 IgG or eosinophil counts. Correlation analysis revealed positive links between periostin levels in serum and attributes such as urticaria/erythema lesions, total IgE levels, serum BP180 IgG, BP180 IgE, BP230 IgE, and blood eosinophil counts. The findings from the Olink proteomic analysis provided additional evidence of the connection between periostin and type II inflammation in BP, which was further validated by the observed positive correlation between periostin and IL-13 using ELISA. Furthermore, it was observed that serum periostin levels decreased post-effective treatment. Overall, this study underscores a compelling association between periostin expression and the activity and severity of BP, as well as its reflection of type II inflammation.

Meteorin-like protein/METRNL/Interleukin-41 ameliorates atopic dermatitis-like inflammation

BACKGROUND

Meteorin-like protein (METRNL)/Interleukin-41 (IL-41) is a novel immune-secreted cytokine/myokine involved in several inflammatory diseases. However, how METRNL exerts its regulatory properties on skin inflammation remains elusive. This study aims to elucidate the functionality and regulatory mechanism of METRNL in atopic dermatitis (AD).

METHODS

METRNL levels were determined in skin and serum samples from patients with AD and subsequently verified in the vitamin D3 analogue MC903-induced AD-like mice model. The cellular target of METRNL activity was identified by multiplex immunostaining, single-cell RNA-seq and RNA-seq.

RESULTS

METRNL was significantly upregulated in lesions and serum of patients with dermatitis compared to healthy controls (p <.05). Following repeated MC903 exposure, AD model mice displayed elevated levels of METRNL in both ears and serum. Administration of recombinant murine METRNL protein (rmMETRNL) ameliorated allergic skin inflammation and hallmarks of AD in mice, whereas blocking of METRNL signaling led to the opposite. METRNL enhanced β-Catenin activation, limited the expression of Th2-related molecules that attract the accumulation of Arginase-1 (Arg1)hi macrophages, dendritic cells, and activated mast cells.

CONCLUSIONS

METRNL can bind to KIT receptor and subsequently alleviate the allergic inflammation of AD by inhibiting the expansion of immune cells, and downregulating inflammatory gene expression by regulating the level of active WNT pathway molecule β-Catenin.

Celastrol directly targets LRP1 to inhibit fibroblast-macrophage crosstalk and ameliorates psoriasis progression

Psoriasis is an incurable chronic inflammatory disease that requires new interventions. Here, we found that fibroblasts exacerbate psoriasis progression by promoting macrophage recruitment via CCL2 secretion by single-cell multi-omics analysis. The natural small molecule celastrol was screened to interfere with the secretion of CCL2 by fibroblasts and improve the psoriasis-like symptoms in both murine and cynomolgus monkey models. Mechanistically, celastrol directly bound to the low-density lipoprotein receptor-related protein 1 (LRP1) β-chain and abolished its binding to the transcription factor c-Jun in the nucleus, which in turn inhibited CCL2 production by skin fibroblasts, blocked fibroblast-macrophage crosstalk, and ameliorated psoriasis progression. Notably, fibroblast-specific LRP1 knockout mice exhibited a significant reduction in psoriasis like inflammation. Taken together, from clinical samples and combined with various mouse models, we revealed the pathogenesis of psoriasis from the perspective of fibroblast-macrophage crosstalk, and provided a foundation for LRP1 as a novel potential target for psoriasis treatment.

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.

Single-cell RNA-seq reveals immune cell heterogeneity and increased Th17 cells in human fibrotic skin diseases

Background

Fibrotic skin disease represents a major global healthcare burden, characterized by fibroblast hyperproliferation and excessive accumulation of extracellular matrix components. The immune cells are postulated to exert a pivotal role in the development of fibrotic skin disease. Single-cell RNA sequencing has been used to explore the composition and functionality of immune cells present in fibrotic skin diseases. However, these studies detected the gene expression of all cells in fibrotic skin diseases and did not enrich immune cells. Thus, the precise immune cell atlas in fibrotic skin diseases remains unknown. In this study, we plan to investigate the intricate cellular landscape of immune cells in keloid, a paradigm of fibrotic skin diseases.

Methods

CD45+ immune cells were enriched by fluorescence-activated cell sorting. Single-cell RNA sequencing was used to analyze the cellular landscape of immune cells in keloid and normal scar tissues. Ki-67 staining, a scratch experiment, real-time PCR, and Western blotting were used to explore the effect of the Th17 cell supernatant on keloid fibroblasts.

Results

Our findings revealed the intricate cellular landscape of immune cells in fibrotic skin diseases. We found that the percentage of Th17 cells was significantly increased in keloids compared to normal scars. All the subclusters of macrophages and dendritic cells (DCs) showed similar proportions between keloid samples and normal scar samples. However, upregulated genes in keloid M1 macrophages, M2 macrophages, and cDC2 are associated with the MHC class II protein complex assembly and antigen assembly, indicating that macrophages and cDC2 are active in keloids. Functional studies suggested that the supernatant of Th17 cells could promote proliferation, collagen expression, and migration of keloid fibroblasts through interleukin 17A. Importantly, increased Th17 cells are also found in other fibrotic skin diseases, such as hypertrophic scars and scleroderma, suggesting this represents a broad mechanism for skin fibrosis.

Conclusion

In summary, we built a single-cell atlas of fibrotic skin diseases in this study. In addition, we explored the function of Th17 cell-fibroblast interaction in skin fibrosis. These findings will help to understand fibrotic skin disease pathogenesis in depth and identify potential targets for fibrotic skin disease treatment.

Role of Arg1+ ILC2s and ILCregs in gestational diabetes progression

Innate lymphoid cells (ILCs) are a newly discovered subset of immune cells that are responsible for regulation of the immune microenvironment. In particular, the ILC categories ILC2s and regulatory ILCs (ILCregs) are associated with immunosuppression and chronic inflammation. Chronic low-grade inflammation leads to insulin resistance, a major etiological factor in gestational diabetes mellitus (GDM). However, the influence of ILCs on GDM remains poorly understood. Therefore, this study aims to investigate the potential role of ILCs in the development and progression of GDM. This study included 19 patients diagnosed with GDM and 19 age- and body mass index-matched individuals in the control group. Flow cytometry was employed to assess the frequency and function of ILC subsets in peripheral blood (PB), cord blood (CB), and placental tissues. Additionally, ELISA was utilized to measure the levels of the cytokines TNF-α, IFN-γ, TGF-β, and IL-4/10/13/22 in the serum samples of patients. Compared to the control group with normal pregnancy, significantly elevated levels of ILC2s, Arg1+ILC2s, and ILCregs were detected in the PB, CB, and placental tissues of the GDM group. With regard to inflammation-related cytokines, the levels of IL-13/22 in PB serum were significantly elevated, while the TGF-β levels were significantly reduced in the GDM group compared to the control group (CG). Further, in the CB serum samples, IL-13 levels were elevated in the GDM group. Additionally, a negative correlation was observed between the number of ILC3s and the number of ILCregs present in umbilical cord blood, while the IL-13 level in peripheral blood was negatively correlated with the number of ILC3s. The present findings indicate that chronic low-grade inflammation mediated by Arg-1+ILC2s and ILCregs is closely associated with the pathogenesis of GDM.

The impact of PTEN status on glioblastoma multiforme: A glial cell type-specific study identifies unique prognostic markers

Glioblastoma multiforme (GBM) is the most invasive form of brain tumor, accounting for 5 % of the cases per 100,000 people in various countries. The phosphatase and tensin homolog deleted from chromosome 10 (PTEN) is a well-known tumor suppressor, and its alteration leads to a deleterious effect on GBM progression. The molecular mechanism of tumorigenesis in glial cell types, driven by PTEN status, is yet to be elucidated. In this study, we analyzed publicly available single-cell transcriptome profiles of PTEN wild-type (WT) and NULL GBM patients. We compared them with normal brain data to uncover many unique gene sets influenced by PTEN status. The co-expression network analysis of differentially expressed genes (DEGs) between normal brain and PTEN (WT and NULL) identified highly interconnected genes. The weighted gene co-expression network analysis (WGCNA), based on the DESeq2 algorithm, identified glial cell-type-specific modules in PTEN status-dependent bulk RNA expression profiles. We overlapped network module gene sets from single-cell and bulk transcriptome profiles, and shared genes were considered for further analysis. The hallmark pathway enrichment analysis of the genes unique to PTEN-WT and NULL revealed various tumor growth-related pathways across the glial cell types. Further characterization of PTEN-WT and PTEN-NULL networks belonging to the single-cell and bulk RNA datasets revealed that PTEN status influences the network modules in astrocytes, microglia, and oligodendrocyte precursor cells. An integrated influence value algorithm identified hub genes for each glial cell type. The prognostic analysis identified clinically relevant hub genes specific to the cell type in PTEN-WT: GLIPR2 (astrocytes), CFH, IL32, MXRA5 (microglia), and PTEN-NULL: ID1 (astrocytes) and LAT2 (microglia). Our glial cell type-level transcriptome analysis unearthed unique molecular pathways and prognostic markers in PTEN status-dependent GBM patients.

nipalsMCIA: flexible multi-block dimensionality reduction in R via nonlinear iterative partial least squares

SUMMARY

With the increased reliance on multi-omics data for bulk and single-cell analyses, the availability of robust approaches to perform unsupervised learning for clustering, visualization, and feature selection is imperative. We introduce nipalsMCIA, an implementation of multiple co-inertia analysis (MCIA) for joint dimensionality reduction that solves the objective function using an extension to Nonlinear Iterative Partial Least Squares. We applied nipalsMCIA to both bulk and single-cell datasets and observed significant speed-up over other implementations for data with a large sample size and/or feature dimension.

AVAILABILITY AND IMPLEMENTATION

nipalsMCIA is available as a Bioconductor package at https://bioconductor.org/packages/release/bioc/html/nipalsMCIA.html, and includes detailed documentation and application vignettes.

Human T Helper 9 Cells Rely on Peroxisome Proliferator-Activated Receptor-γ-Mediated Cystine Uptake to Prevent Lipid Peroxidation and Bioenergetic Failure

T helper 9 (Th9) cells are implicated in allergic skin inflammation and depend on the transcription factor peroxisome proliferator-activated receptor-γ (PPAR-γ) for full effector function. In this study, we uncovered a role for PPAR-γ in the amino acid metabolism of human Th9 cells. In in vitro-primed Th9 cells, PPAR-γ expression positively correlated with the expression of SLC7A8, which encodes LAT2, a transporter of large neutral amino acids, including cystine. Inhibition of PPAR-γ led to a compensatory upregulation of SLC7A11, a subunit of the cystine-glutamine antiporter xCT, indicating a specific need for cystine uptake in Th9 cells. Indeed, Th9 cells were sensitive to cystine deprivation, which triggered lipid peroxidation and bioenergetic failure, resulting in a ferroptosis-like form of cell death. This outcome was further enforced by additional PPAR-γ inhibition. Finally, combined SLC7A11 and PPAR-γ inhibition depleted Th9 cells in ex vivo samples of acute allergic skin inflammation. Overall, our data suggest that human Th9 cells are dependent on uptake of exogenous cystine, which opens up promising therapeutic strategies for their inhibition or depletion in allergic skin inflammation.

Immune modules to guide diagnosis and personalized treatment of inflammatory skin diseases

Previous advances have identified immune pathways associated with inflammatory skin diseases, leading to the development of targeted therapies. However, there is a lack of molecular approaches that delineate these pathways at the individual patient level for personalized diagnostic and therapeutic guidance. Here, we conduct a cross-comparison of expression profiles from multiple inflammatory skin diseases to identify gene modules defining relevant immune pathways. Seven modules are identified, representing key immune pathways: Th17, Th2, Th1, Type I IFNs, neutrophilic, macrophagic, and eosinophilic. These modules allow the development of a molecular map with high diagnostic efficacy for inflammatory skin diseases and clinico-pathologically undetermined cases. Aligning dominant modules with treatment targets offers a rational framework for treatment selection, improving response rates in both treatment-naïve patients and non-responders to targeted therapies. Overall, our approach offers precision medicine for inflammatory skin diseases, utilizing transcriptional modules to support diagnosis and guide personalized treatment selection.

Identification of CD19 as a shared biomarker via PPARγ/β-catenin/Wnt3a pathway linking psoriasis and major depressive disorder

BACKGROUND

Psoriasis, a chronic inflammatory skin disorder, is frequently linked with metabolic, cardiovascular, and psychological comorbidities. Recent research has highlighted the correlation between psoriasis and major depressive disorder (MDD); however, the underlying mechanism remains unclear.

METHODS

Commonly differentially expressed genes (DEGs) in psoriasis and MDD were identified and visualized using data from the GEO database. Subsequently, functional enrichment analysis was conducted using Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Genemania. The hub gene was selected through LASSO and Random Forest algorithms, validated in clinical tissues using Student's t-test and Receiver Operating Characteristic curve. To investigate the hub gene's function in disease phenotype, we established imiquimod (IMQ)-induced psoriasiform dermatitis and chronic unpredictable mild stress (CUMS) mouse models. Lentiviral shRNA interference was topically applied in mice, and downstream pathways were validated at the mRNA and protein levels.

RESULTS

A total of 395 overlapping DEGs were identified from GSE121212 and GSE54568 datasets, and twenty core genes were extracted. Functional enrichment analysis revealed that the core genes were significantly associated with the Wnt signaling pathway, neurodegeneration, and energy metabolism. CD19 was identified as the hub gene through algorithms, and external validation showed remarkable AUC values of 0.69 and 0.74, respectively. The level of CD19 increased significantly in IMQ-treated and CUMS-treated mice. Suppression of CD19 significantly alleviated the phenotypes of IMQ-induced psoriasiform dermatitis and CUMS-induced depressive-like behaviors by regulating the PPARγ/β-catenin/Wnt3a pathway.

CONCLUSION

CD19 may serve as a common biomarker or therapeutic target of psoriasis and MDD via PPARγ/β-catenin/Wnt3a pathway.

Impact of inflammatory skin conditions on the biological profile of plasma rich in growth factor

Plasma rich in growth factors (PRGF) can be used over patients suffering from dermatoses due to its anti-inflammatory effect. However, this population group might present soluble autoimmune components and there is limited information about the effect of chronic skin inflammation on PRGF bioactive properties. With the aim of characterizing PRGF composition, PRGF from healthy (H) donors and patients with atopic dermatitis (AD), psoriasis (PS), or lichen sclerosus (LS) was obtained. In order to reduce the inflammatory component, leukocyte exclusion and heat-inactivation (Immunosafe) were tested. Haematological-serological parameters, platelet functionality, clot microstructure, protein content and bioactivity were determined. Mean values and 95 % confidence intervals (mean[95 % CI]) were computed for key haematological parameters, such as platelet (410×103/mm3[371-449]) and leukocyte content (205×103/mm3[148-262]), platelet activation (resting: 4.3 %[3.1-5.5] and activated: 97.4 %[96.7-98.0]), the concentration of plasma proteins and morphogens, including immunoglobulins A (210.7 mg/dL[191.8-229.6]), G (933.1 mg/dL[887.2-978.9]), E (783.5 mg/dL[54.4-1512.6]), and M (115.0 mg/dL[97.1-133.0]), Complement Protein (31.6 mg/mL[26.6-36.6]), C-Reactive protein (3.1 mg/L[2.0-4.1]), TGF-β1 (35975.6 pg/mL[34221.3-37729.8]), fibronectin (146410.0 ng/mL[136518.3-156301.7]), PDGF-AB (13308.5 pg/mL[12401.0-14216.0]), CD40L (2389.3 pg/mL[1887.7-2890.8]), IL-4 (0.12 pg/mL[0.07-0.18]), IL-13 (35.4 pg/mL[21.0-49.7]), IL-1β (0.09 pg/mL[0.06-0.11]) and TNF-α (0.31 pg/mL[0.24-0.38]), and also for cell proliferation (332.9ngDNA/mL[317.4-348.3]), viability (135.6 %[132.0-139.2]) and migration (103.8cells/mm2[98.3-109.3]). Plasma from AD donors presented increased Immunoglobulin E (IgE) that was significantly reduced after Immunosafe along with the complement system and autoantibodies. Platelet functionality was altered for AD, but no microstructure differences were identified. Pathological groups presented reduced concentration of fibronectin (AD/LS) and Platelet-Derived Growth Factor (PDGF-AB) (P). Immunosafe treatment reduced Cluster of Differentiation 40 Protein (CD40L), interleukin 1β (IL-1β), and Tumor Necrosis Factor α (TNF-α) concentrations. Fibroblasts supplemented with PRGF obtained from pathological patients (PS/AD) showed reduced viability but Immunosafe increased cell proliferation and migration in SP (LS) and L-SP samples (PS/AD). In conclusion, PRGF derived from pathological patients present autoimmune components, but heat-inactivation or leukocyte exclusion could minimize local side effects.

Omics in allergy and asthma

This review explores the transformative impact of omics technologies on allergy and asthma research in recent years, focusing on advancements in high-throughput technologies related to genomics and transcriptomics. In particular, the rapid spread of single-cell RNA sequencing has markedly advanced our understanding of the molecular pathology of allergic diseases. Furthermore, high-throughput genome sequencing has accelerated the discovery of monogenic disorders that were previously overlooked as ordinary intractable allergic diseases. We also introduce microbiomics, proteomics, lipidomics, and metabolomics, which are quickly growing areas of research interest, although many of their current findings remain inconclusive as solid evidence. By integrating these omics data, we will gain deeper insights into disease mechanisms, leading to the development of precision medicine approaches that promise to enhance treatment outcomes.

Oroxylin A attenuates psoriasiform skin inflammation by direct targeting p62 (sequestosome 1) via suppressing M1 macrophage polarization

BACKGROUND AND PURPOSE

Psoriasis results from the interplay of innate and adaptive immunity in the skin. Oroxylin A (OA) has shown anti-inflammatory effects in various disorders. This study explores oroxylin A potential in treating psoriasis, particularly its impact on type I macrophage (Mφ1) polarization.

EXPERIMENTAL APPROACH

Oroxylin A-mediated therapeutic effects were evaluated using imiquimod-induced or IL-23-injected psoriatic mice models, followed by proteomics assays to predict potential signalling and targeting proteins. Immunofluorescence and immunoblot assays verified that oroxylin A suppresses NF-κB signalling in Mφ1 macrophages. Co-immunoprecipitation and microscale thermophoresis (MST) assays further demonstrated that p62 (sequestosome 1) is the target protein for oroxylin A in macrophages. Oroxylin A-p62-mediated suppression of psoriasis was validated in an imiquimod-induced p62 conditional knockout (cKO) mice model.

KEY RESULTS

Oroxylin A demonstrated therapeutic efficacy in murine models induced by imiquimod or IL-23 by attenuating cutaneous inflammation and mitigating Mφ1 polarization via NF-κB signalling. Proteomics analysis suggested SQSTM1/p62 as a key target, confirmed to interact directly with oroxylin A. Oroxylin A disrupted the p62-PKCζ interaction by binding to PB1 domain of p62. Its anti-inflammatory effects were significantly reduced in macrophages from p62 cKO mice compared to the wild-type (WT) mice in psoriasis model, supporting oroxylin A role in suppressing Mφ1 polarization through its interaction with p62.

CONCLUSION AND IMPLICATIONS

Our findings demonstrated oroxylin A suppressed psoriasiform skin inflammation in mouse models by blocking the PKCζ-p62 interaction, subsequently inhibiting the activation of NF-κB p65 phosphorylation in macrophages.

Multi-omic analysis revealed the immunological patterns and diagnostic value of exhausted T cell-derived PTTG1 in patients with psoriasis

BACKGROUND

Psoriasis, characterized by chronic inflammation, is a persistent skin condition that is notoriously challenging to manage and prone to relapse. Despite significant advancements in its treatment, many adverse reactions still occur. Therefore, exploring the mechanisms behind the occurrence and development of psoriasis is extremely important.

METHODS

The weighted correlation network analysis (WGCNA) algorithm was used to identify phenotype-related genes in patients with psoriasis. We recruited clinical samples of patients with psoriasis, and used single-cell RNA sequencing (scRNA-seq) to visualize divergent genes and metabolisms of varied cells for the psoriasis. Various machine-learning methods were used to identify core genes, and molecular docking was used to analyze the stability of leptomycin B targeting pituitary tumor transforming 1 (PTTG1). Immunofluorescence (IHC) analysis, multiplex immunofluorescence (mIF) analysis, and quantitative reverse transcription polymerase chain reaction (qRT-PCR) were used to validate the results.

RESULTS

Our results identified 1391 genes associated with the phenotype in patients with psoriasis and highlighted the significant alterations in T-cell functionality observed in the disease by WGCNA. There were nine distinct cellular clusters in psoriasis analyzed with the aid of scRNA-seq data. Each subtype of cell exhibited distinct genetic profiles, functional roles, signaling mechanisms, and metabolic characteristics. Machine-learning methods further demonstrated the potential diagnostic value of T cell-derived PTTG1 and its relationship with T-cell exhaustion in psoriasis. Lastly, the leptomycin B was scrutinized and verified had high stability targeting PTTG1.

CONCLUSIONS

This study elucidates the biological basis of psoriasis. At the same time, it was discovered that PTTG1 derived from exhausted T cells serves as a diagnostic biomarker for psoriasis. Leptomycin B could be a potential drug for targeted treatment of psoriasis on PTTG1.

Single-cell analysis in rheumatic and allergic diseases: insights for clinical practice

Since the advent of single-cell RNA sequencing (scRNA-seq) methodology, single-cell analysis has become a powerful tool for exploration of cellular networks and dysregulated immune responses in disease pathogenesis. Advanced bioinformatics tools have enabled the combined analysis of scRNA-seq data and information on various cell properties, such as cell surface molecular profiles, chromatin accessibility and spatial information, leading to a deeper understanding of pathology. This Review provides an overview of the achievements in single-cell analysis applied to clinical samples of rheumatic and allergic diseases, including rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis, allergic airway diseases and atopic dermatitis, with an expanded scope beyond peripheral blood cells to include local diseased tissues. Despite the valuable insights that single-cell analysis has provided into disease pathogenesis, challenges remain in translating single-cell findings into clinical practice and developing personalized treatment strategies. Beyond understanding the atlas of cellular diversity, we discuss the application of data obtained in each study to clinical practice, with a focus on identifying biomarkers and therapeutic targets.

IL-23 inhibition for chronic inflammatory disease

Biological monoclonal antibody drugs inhibit overactive cytokine signalling that drives chronic inflammatory disease in different organ systems. In the last 10 years, interleukin (IL)-23 inhibitors have attained an important position in the treatment of psoriatic skin and joint disease as well as inflammatory bowel diseases. Addressing an upstream pathological mechanism shared between these disorders, this drug class has high efficacy rates and a durable response that extends dosing intervals up to 3 months. Pooled clinical trial data show objective disease improvement for more than 70% of patients with psoriasis and up to 50% of patients with inflammatory bowel disease. The first antibody inhibitor for IL-23A targeted a p40 subunit shared with IL-12. Subsequently, even greater improvement was established for inhibitors of the p19 protein unique to IL-23A. IL-23 p19 inhibitors elicit clinical response in both bio-naive and bio-exposed patients and show superiority to tumour necrosis factor α inhibitors in plaque psoriasis. Reported differences in efficacy between p19 inhibitors suggest that individual drug action might be modulated by antibody affinity. Although long-term safety data are accumulating, rates of serious adverse events and infections for interleukin (IL)-23 inhibitors are similar to the rates for placebo across approved indications.

The regulatory T cell-selective interleukin-2 receptor agonist rezpegaldesleukin in the treatment of inflammatory skin diseases: two randomized, double-blind, placebo-controlled phase 1b trials

Regulatory T cell (Treg) impairment is implicated in the pathogenesis of chronic inflammatory diseases, but relatively little is known about the therapeutic potential of Treg restoration. Here we present clinical evidence for the Treg-selective interleukin-2 receptor agonist rezpegaldesleukin (REZPEG) in two randomized, double-blind, placebo-controlled Phase 1b trials in patients with moderate-to-severe atopic dermatitis (AD) (NCT04081350) or chronic plaque psoriasis (PsO) (NCT04119557). Key inclusion criteria for AD included an Eczema Area and Severity Index (EASI) score ≥ 16 and a validated Investigator Global Assessment for Atopic Dermatitis (vIGA-AD) ≥ 3, and for PsO included a Psoriasis Area and Severity Index (PASI) score of ≥ 12 and a static Physician's Global Assessment (sPGA) score of ≥ 3. REZPEG is safe and well-tolerated and demonstrates consistent pharmacokinetics in participants receiving subcutaneous doses of 10 to 12 µg/kg or 24 µg/kg once every 2 weeks for 12 weeks, meeting the primary and secondary objectives, respectively. AD patients receiving the higher dose demonstrate an 83% improvement in EASI score after 12 weeks of treatment. EASI improvement of ≥ 75% (EASI-75) and vIGA-AD responses are maintained for 36 weeks after treatment discontinuation in 71% and 80% of week 12 responders, respectively. These exploratory clinical improvements are accompanied by sustained increases in CD25bright Tregs. REZPEG thus represents a homeostatic approach to cutaneous disease therapy and holds clinical potential in providing long-term, treatment-free disease control.

Secukinumab in adult patients with lichen planus: efficacy and safety results from the randomized placebo-controlled proof-of-concept PRELUDE study

BACKGROUND

Patients with lichen planus (LP) refractory to available therapies often experience a high disease burden, representing a population with a clear unmet need for new treatments.

OBJECTIVES

To evaluate the efficacy and safety of secukinumab 300 mg over 32 weeks in adult patients with biopsy-proven cutaneous LP (CLP), mucosal LP (MLP) or lichen planopilaris (LPP) that is inadequately controlled by topical corticosteroids.

METHODS

PRELUDE was a randomized double-blind placebo-controlled phase II proof-of-concept study that enrolled patients with CLP, MLP or LPP. Eligible patients were randomized to either secukinumab 300 mg every 4 weeks for 32 weeks (SECQ4W) or placebo for 16 weeks followed by secukinumab 300 mg every 2 weeks (SECQ2W) for 16 weeks. The primary endpoint was achievement of the newly designed Investigator's Global Assessment (IGA) score ≤ 2 at week 16.

RESULTS

Overall, 111 patients were randomized (n = 37 each) to CLP, MLP and LPP cohorts. As the proof-of-concept criteria were not met for any of the three cohorts, the primary objective was not met. A numerically higher proportion of patients achieved IGA ≤ 2 response at week 16 with SECQ4W vs. placebo in the MLP {37.5% [95% credibility interval (Crl) 20.3-57.2] vs. 23.1% (95% Crl 6.5-49.2)} and LPP cohorts [37.5% (95% Crl 20.2-57.3) vs. 30.8% (95% Crl 10.8-57.6)]. In the LPP cohort, a sustained response for IGA ≤ 2 from week 16 to week 32 was achieved with SECQ4W (week 16, 37.5%; week 32, 45.8%), and a substantial improvement was observed in IGA ≤ 2 response in patients from this cohort who switched from placebo (week 16, 30.8%) to SECQ2W after week 16 (week 32, 63.6%). The safety profile was consistent with the known profile of secukinumab and showed no new or unexpected signals.

CONCLUSIONS

PRELUDE is the first randomized controlled basket trial evaluating interleukin (IL)-17A inhibition with secukinumab across three subtypes of LP. Secukinumab was well tolerated and safe, showing different response rates across the three subtypes, with numerical IGA improvements in MLP and LPP, and no response in CLP. The study raises the question of a differential role of IL-17A across LP subtypes. The novel IGA score showed significant correlation with both patient- and physician-reported outcome measurements.

The levels of amino acid metabolites in serum induce the pathogenesis of atopic dermatitis by mediating the inflammatory protein S100A12

Atopic dermatitis (AD) is a chronic inflammatory skin disease affecting tens of millions of people globally. The causal relationship between metabolites and AD pathology has not yet been formally indicated, and the mediating mechanism by which metabolites affect AD has not yet been explored. This study aimed to determine the genetic relationship between metabolites and AD and to determine the pathways through which amino acid metabolites affect AD. Meta-analysis integrates the results of multiple GWAS analyses using METAL software. Using bidirectional two-sample Mendelian randomization (MR), we analyzed the causal relationships between metabolites and AD. The principal MR test of causal effects was conducted using inverse-variance weighted regression, and we used reverse MR analysis to exclude reverse causality. We also performed the MR-PRESSO test to detect and correct for possible pleiotropic effects, and used the Cochran Q test to assess heterogeneity. Two-step MR was utilized to analyze the mediating factors between amino acid metabolites and the onset of AD. The correlation between mediating factors (inflammatory protein S100A12) and immune cell infiltration was analyzed using the edgeR and GSVA software packages. Using single-cell sequencing data from skin tissues of patients with AD, we studied the regulatory role of the S100A12 gene in immune cells. Multiple drug databases and macromolecular docking were used to search for S100A12-targeting drugs. Bidirectional two-sample MR analyses indicated that twenty-two metabolites and one inflammatory protein (S100A12) were significantly associated with AD pathogenesis. S100A12 is a mediator of amino acid metabolites (N6-methyllysine; N2-acetyl,N6,N6-dimethyllysine and N6,N6-dimethyllysine) that are genetically associated with AD. S100A12 was positively correlated with the infiltration of multiple immune cell types in lesional AD skin. The amino acid metabolites N6-methyllysine; N2-acetyl,N6,N6-dimethyllysine and N6,N6-dimethyllysine influence AD pathogenesis by mediating S100A12 expression.

Cold atmospheric plasma (CAP): a revolutionary approach in dermatology and skincare

Cold atmospheric plasma (CAP) technology has emerged as a revolutionary therapeutic technology in dermatology, recognized for its safety, effectiveness, and minimal side effects. CAP demonstrates substantial antimicrobial properties against bacteria, viruses, and fungi, promotes tissue proliferation and wound healing, and inhibits the growth and migration of tumor cells. This paper explores the versatile applications of CAP in dermatology, skin health, and skincare. It provides an in-depth analysis of plasma technology, medical plasma applications, and CAP. The review covers the classification of CAP, its direct and indirect applications, and the penetration and mechanisms of action of its active components in the skin. Briefly introduce CAP's suppressive effects on microbial infections, detailing its impact on infectious skin diseases and its specific effects on bacteria, fungi, viruses, and parasites. It also highlights CAP's role in promoting tissue proliferation and wound healing and its effectiveness in treating inflammatory skin diseases such as psoriasis, atopic dermatitis, and vitiligo. Additionally, the review examines CAP's potential in suppressing tumor cell proliferation and migration and its applications in cosmetic and skincare treatments. The therapeutic potential of CAP in treating immune-mediated skin diseases is also discussed. CAP presents significant promise as a dermatological treatment, offering a safe and effective approach for various skin conditions. Its ability to operate at room temperature and its broad spectrum of applications make it a valuable tool in dermatology. Finally, introduce further research is required to fully elucidate its mechanisms, optimize its use, and expand its clinical applications.

Resilience of dermis resident macrophages to inflammatory challenges

The skin serves as a complex barrier organ populated by tissue-resident macrophages (TRMs), which play critical roles in defense, homeostasis, and tissue repair. This review examines the functions of dermis resident TRMs in different inflammatory settings, their embryonic origins, and their long-term self-renewal capabilities. We highlight the M2-like phenotype of dermal TRMs and their specialized functions in perivascular and perineuronal niches. Their interactions with type 2 immune cells, autocrine cytokines such as IL-10, and their phagocytic clearance of apoptotic cells have been explored as mechanisms for M2-like dermal TRM self-maintenance and function. In conclusion, we address the need to bridge murine models with human studies, with the possibility of targeting TRMs to promote skin immunity or restrain cutaneous pathology.

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 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.

Recruitment of CXCR4+ type 1 innate lymphoid cells distinguishes sarcoidosis from other skin granulomatous diseases

Sarcoidosis is a multiorgan granulomatous disease that lacks diagnostic biomarkers and targeted treatments. Using blood and skin from patients with sarcoid and non-sarcoid skin granulomas, we discovered that skin granulomas from different diseases exhibit unique immune cell recruitment and molecular signatures. Sarcoid skin granulomas were specifically enriched for type 1 innate lymphoid cells (ILC1s) and B cells and exhibited molecular programs associated with formation of mature tertiary lymphoid structures (TLSs), including increased CXCL12/CXCR4 signaling. Lung sarcoidosis granulomas also displayed similar immune cell recruitment. Thus, granuloma formation was not a generic molecular response. In addition to tissue-specific effects, patients with sarcoidosis exhibited an 8-fold increase in circulating ILC1s, which correlated with treatment status. Multiple immune cell types induced CXCL12/CXCR4 signaling in sarcoidosis, including Th1 T cells, macrophages, and ILCs. Mechanistically, CXCR4 inhibition reduced sarcoidosis-activated immune cell migration, and targeting CXCR4 or total ILCs attenuated granuloma formation in a noninfectious mouse model. Taken together, our results show that ILC1s are a tissue and circulating biomarker that distinguishes sarcoidosis from other skin granulomatous diseases. Repurposing existing CXCR4 inhibitors may offer a new targeted treatment for this devastating disease.

The impact of lipidome on five inflammatory skin diseases: a Mendelian randomization study

OBJECTIVE

Two-sample Mendelian randomization (TSMR) was employed to examine the association between lipidome and five inflammatory skin diseases.

METHOD

To evaluate the association between various molecular subtypes of lipidome and the risk of five inflammatory skin diseases, we analyzed a comprehensive GWAS dataset comprising 179 lipidome. The Two-Sample Mendelian Randomization (TSMR) method was employed to investigate causal relationships. Heterogeneity and pleiotropy were assessed using Cochran's Q test, MR-Egger intercept test, and MR-PRESSO global test. Additionally, a sensitivity analysis was conducted to evaluate the influence of individual single nucleotide polymorphisms on Mendelian Randomization study.

RESULTS

Using 179 serum lipidome as exposures and five common inflammatory skin diseases as outcomes, we investigated their associations in this large-scale study. Our findings reveal significant impacts of glycerophospholipids, glycerolipids, and sphingomyelins on inflammatory skin diseases. Glycerophospholipids were protective against pemphigus but predominantly posed risks for other inflammatory skin diseases. Specifically, phosphatidylcholine (16:0_0:0) exhibited the most significant risk association with lichen planus (OR = 1.25, 95% CI 1.11-1.40, P < 0.001). Conversely, glycerolipids showed no effect on lichen planus but were protective against pemphigus while potentially posing risks for other conditions. Triacylglycerol (46:2) showed the most substantial risk association with vitiligo (OR = 1.99, 95% CI 1.35-2.93, P < 0.001). Furthermore, sphingomyelins had no effect on atopic dermatitis but posed potential risks for other inflammatory skin diseases. Sphingomyelin (d40:1) notably emerged as a significant risk factor for pemphigus (OR = 1.91, 95% CI 1.37-2.66, P < 0.001).

CONCLUSIONS

This study has elucidated the potential harmful effects of glycerophospholipids, glycerolipids, and sphingomyelins on inflammatory skin diseases, while also providing valuable insights for future research into the pathophysiology, prevention and treatment of these conditions.

Decreased GATA3 levels cause changed mouse cutaneous innate lymphoid cell fate, facilitating hair follicle recycling

In mice, skin-resident type 2 innate lymphoid cells (ILC2s) exhibit some ILC3-like characteristics. However, the underlying mechanism remains elusive. Here, we observed lower expression of the ILC2 master regulator GATA3 specifically in cutaneous ILC2s (cILC2s) compared with canonical ILC2s, in line with its functionally divergent role in transcriptional control in cILC2s. Decreased levels of GATA3 enabled the expansion of RORγt fate-mapped (RORγtfm+) cILC2s after postnatal days, displaying certain similarities to ILC3s. Single-cell trajectory analysis showed a sequential promotion of the RORγtfm+ cILC2 divergency by RORγt and GATA3. Notably, during hair follicle recycling, these RORγtfm+ cILC2s accumulated around the hair follicle dermal papilla (DP) region to facilitate the process. Mechanistically, we found that GATA3-mediated integrin α3β1 upregulation on RORγtfm+ cILC2s was required for their positioning around the DP. Overall, our study demonstrates a distinct regulatory role of GATA3 in cILC2s, particularly in promoting the divergence of RORγtfm+ cILC2s to facilitate hair follicle recycling.

Non-coding RNAs as skin disease biomarkers, molecular signatures, and therapeutic targets

Non-coding RNAs (ncRNAs) are emerging as biomarkers, molecular signatures, and therapeutic tools and targets for diseases. In this review, we focus specifically on skin diseases to highlight how two classes of ncRNAs-microRNAs and long noncoding RNAs-are being used to diagnose medical conditions of unclear etiology, improve our ability to guide treatment response, and predict disease prognosis. Furthermore, we explore how ncRNAs are being used as both as drug targets and associated therapies have unique benefits, risks, and challenges to development, but offer a distinctive promise for improving patient care and outcomes.

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.

Effect of Health Status and Heat-Induced Inactivation on the Proteomic Profile of Plasma Rich in Growth Factors Obtained from Donors with Chronic Inflammatory Skin Conditions

Atopic dermatitis, psoriasis and lichen sclerosus are among the most challenging conditions treated by dermatologists worldwide, with potentially significant physical, social and psychological impacts. Emerging evidence suggests that autologous-platelet-rich plasma could be used to manage skin inflammation. However, the presence of soluble autoimmune components could hinder their therapeutic potential. The aim of this study was to analyze the proteomic profile of plasma rich in growth factors (PRGFs) obtained from donors with inflammatory skin conditions to evaluate the impact of skin health status on the composition and bioactivity of PRGF-based treatments. Venous blood from healthy volunteers and patients with psoriasis, lichen sclerosus and atopic dermatitis was processed to produce PRGF supernatant. Half of the samples were subjected to an additional thermal treatment (56 °C) to inactivate inflammatory and immune molecules. Proteomic analysis was performed to assess the protein profile of PRGFs from healthy and non-healthy patients and the effect of Immunosafe treatment. Differential abundance patterns of several proteins related to key biological processes have been identified, including complement activation, blood coagulation, and glycolysis- and gluconeogenesis-related genes. These results also demonstrate that the thermal treatment (Immunosafe) contributes to the inactivation of the complement system and, as a consequence, reduction in the immunogenic potential of PRGF products.

Mapping the immune cell landscape of severe atopic dermatitis by single-cell RNA-seq

BACKGROUND

Efforts to profile atopic dermatitis (AD) tissues have intensified, yet comprehensive analysis of systemic immune landscapes in severe AD remains crucial.

METHODS

Employing single-cell RNA sequencing, we analyzed over 300,000 peripheral blood mononuclear cells from 12 severe AD patients (Eczema area and severity index (EASI) > 21) and six healthy controls.

RESULTS

Results revealed significant immune cell shifts in AD patients, including increased Th2 cell abundance, reduced NK cell clusters with compromised cytotoxicity, and correlated Type 2 innate lymphoid cell proportions with disease severity. Moreover, unique monocyte clusters reflecting activated innate immunity emerged in very severe AD (EASI > 30). While overall dendritic cells (DCs) counts decreased, a distinct Th2-priming subset termed "Th2_DC" correlated strongly with disease severity, validated across skin tissue data, and flow cytometry with additional independent severe AD samples. Beyond the recognized role of Th2 adaptive immunity, our findings highlight significant innate immune cell alterations in severe AD, implicating their roles in disease pathogenesis and therapeutic potentials.

CONCLUSION

Apart from the widely recognized role of Th2 adaptive immunity in AD pathogenesis, alterations in innate immune cells and impaired cytotoxic cells have also been observed in severe AD. The impact of these alterations on disease pathogenesis and the effectiveness of potential therapeutic targets requires further investigation.

Integrated network pharmacological analysis revealed that Smilax glabra Roxb. alleviates IMQ-induced psoriatic skin inflammation through regulating T cell immune response

ETHNOPHARMACOLOGICAL RELEVANCE

Psoriasis is an autoimmune disease characterized by dysfunctional T cells and dysregulated immune responses. Smilax glabra Roxb. (SGR) is a formulation used in Traditional Chinese Medicine for the treatment of inflammatory skin disorders, including psoriasis. This study explores the scientific basis for its use by examining the effects of SGR on T cell differentiation and insulin receptor signaling, relevant pathways implicated in the pathophysiology of psoriasis.

AIM OF THE STUDY

This study investigates the therapeutic potential of SGR (a Chinese medicine) in psoriasis and its impact on T cell differentiation.

MATERIALS AND METHODS

An integrated network pharmacology and bioinformatics approach was employed to elucidate the mechanisms of SGR in regulating T cell differentiation. A psoriasis mouse model was utilized to evaluate the effects of SGR on T cell subsets. Immunohistochemistry and gene expression analyses were conducted to investigate the modulation of insulin receptor signaling pathways by SGR.

RESULTS

SGR treatment effectively reset the expression of various T cell subsets in the psoriasis mouse model, suggesting its ability to regulate T cell differentiation and immune function. Furthermore, SGR treatment inhibited insulin receptor signaling and downstream pathways, including PI3K/AKT and ERK, in psoriatic skin lesions. This indicates that SGR may exert its therapeutic effects through modulation of the insulin receptor signaling pathway.

CONCLUSIONS

This study provides novel insights into the therapeutic potential of SGR in psoriasis. By modulating T cell differentiation and targeting the insulin receptor signaling pathway, SGR holds promise as a potential treatment option for psoriasis.

Heterogeneity and plasticity of tissue-resident memory T cells in skin diseases and homeostasis: a review

Skin tissue-resident memory T (Trm) cells are produced by antigenic stimulation and remain in the skin for a long time without entering the peripheral circulation. In the healthy state Trm cells can play a patrolling and surveillance role, but in the disease state Trm cells differentiate into various phenotypes associated with different diseases, exhibit different localizations, and consequently have local protective or pathogenic roles, such as disease recurrence in vitiligo and maintenance of immune homeostasis in melanoma. The most common surface marker of Trm cells is CD69/CD103. However, the plasticity of tissue-resident memory T cells after colonization remains somewhat uncertain. This ambiguity is largely due to the variation in the functionality and ultimate destination of Trm cells produced from memory cells differentiated from diverse precursors. Notably, the presence of Trm cells is not stationary across numerous non-lymphoid tissues, most notably in the skin. These cells may reenter the blood and distant tissue sites during the recall response, revealing the recycling and migration potential of the Trm cell progeny. This review focuses on the origin and function of skin Trm cells, and provides new insights into the role of skin Trm cells in the treatment of autoimmune skin diseases, infectious skin diseases, and tumors.

TCF1-LEF1 co-expression identifies a multipotent progenitor cell (TH2-MPP) across human allergic diseases

Repetitive exposure to antigen in chronic infection and cancer drives T cell exhaustion, limiting adaptive immunity. In contrast, aberrant, sustained T cell responses can persist over decades in human allergic disease. To understand these divergent outcomes, we employed bioinformatic, immunophenotyping and functional approaches with human diseased tissues, identifying an abundant population of type 2 helper T (TH2) cells with co-expression of TCF7 and LEF1, and features of chronic activation. These cells, which we termed TH2-multipotent progenitors (TH2-MPP) could self-renew and differentiate into cytokine-producing effector cells, regulatory T (Treg) cells and follicular helper T (TFH) cells. Single-cell T-cell-receptor lineage tracing confirmed lineage relationships between TH2-MPP, TH2 effectors, Treg cells and TFH cells. TH2-MPP persisted despite in vivo IL-4 receptor blockade, while thymic stromal lymphopoietin (TSLP) drove selective expansion of progenitor cells and rendered them insensitive to glucocorticoid-induced apoptosis in vitro. Together, our data identify TH2-MPP as an aberrant T cell population with the potential to sustain type 2 inflammation and support the paradigm that chronic T cell responses can be coordinated over time by progenitor cells.

Integrative bioinformatics and experimental validation of hub genetic markers in acne vulgaris: Toward personalized diagnostic and therapeutic strategies

BACKGROUND

Acne vulgaris is a widespread chronic inflammatory dermatological condition. The precise molecular and genetic mechanisms of its pathogenesis remain incompletely understood. This research synthesizes existing databases, targeting a comprehensive exploration of core genetic markers.

METHODS

Gene expression datasets (GSE6475, GSE108110, and GSE53795) were retrieved from the GEO. Differentially expressed genes (DEGs) were identified using the limma package. Enrichment analyses were conducted using GSVA for pathway assessment and clusterProfiler for GO and KEGG analyses. PPI networks and immune cell infiltration were analyzed using the STRING database and ssGSEA, respectively. We investigated the correlation between hub gene biomarkers and immune cell infiltration using Spearman's rank analysis. ROC curve analysis validated the hub genes' diagnostic accuracy. miRNet, TarBase v8.0, and ChEA3 identified miRNA/transcription factor-gene interactions, while DrugBank delineated drug-gene interactions. Experiments utilized HaCaT cells stimulated with Propionibacterium acnes, treated with retinoic acid and methotrexate, and evaluated using RT-qPCR, ELISA, western blot, lentiviral transduction, CCK-8, wound-healing, and transwell assays.

RESULTS

There were 104 genes with consistent differences across the three datasets of paired acne and normal skin. Functional analyses emphasized the significant enrichment of these DEGs in immune-related pathways. PPI network analysis pinpointed hub genes PTPRC, CXCL8, ITGB2, and MMP9 as central players in acne pathogenesis. Elevated levels of specific immune cell infiltration in acne lesions corroborated the inflammatory nature of the disease. ROC curve analysis identified the acne diagnostic potential of four hub genes. Key miRNAs, particularly hsa-mir-124-3p, and central transcription factors like TFEC were noted as significant regulators. In vitro validation using HaCaT cells confirmed the upregulation of hub genes following Propionibacterium acnes exposure, while CXCL8 knockdown reduced pro-inflammatory cytokines, cell proliferation, and migration. DrugBank insights led to the exploration of retinoic acid and methotrexate, both of which mitigated gene expression upsurge and inflammatory mediator secretion.

CONCLUSION

This comprehensive study elucidated pivotal genes associated with acne pathogenesis, notably PTPRC, CXCL8, ITGB2, and MMP9. The findings underscore potential biomarkers, therapeutic targets, and the therapeutic potential of agents like retinoic acid and methotrexate. The congruence between bioinformatics and experimental validations suggests promising avenues for personalized acne treatments.