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Background: Psoriasis is a chronic inflammatory skin disease characterised by disrupted crosstalk between keratinocytes and immune cells, resulting in epidermal dysfunction. Long non-coding RNAs (lncRNAs) regulate gene expression in a cell-or tissue-specific manner, yet their role in psoriatic epidermal dysfunction remains poorly understood.

Objectives: To generate a single-cell atlas of lncRNA expression in healthy and psoriatic epidermis and identify cell state-specific lncRNAs associated with disease.

Methods: Data from Smart-seq2 single-cell RNA sequencing of sorted CD45⁺ and CD45^-epidermal cells from healthy controls and lesional/non-lesional psoriatic skin were analysed. Selected lncRNAs were validated by RT-qPCR, single-molecule in situ hybridisation (RNAscope), and immunofluorescence. The regulation of LINC01137 was studied in IL-17A-treated primary keratinocytes and 3D epidermal models, and its function assessed using siRNA-mediated knockdown in keratinocytes.

Results: We identified 1412 epidermal lncRNAs with robust expression across distinct keratinocyte and immune cell states. LncRNAs exhibited strong cell type-specific expression in both keratinocytes and immune cells, moreover, several lncRNAs showed selective expression in psoriasis-associated cell states. LINC01137 was enriched in activated keratinocytes, induced by IL-17A and correlated with TGF-β pathway activity; its knockdown in primary keratinocytes attenuated TGF-β-induced SERPINE1/PAI-1 expression. LINC00892 was enriched in lesional Th1, Th17 and proliferating CD8⁺T cells and showed increased expression as well as co-localisation with the T cell marker CD3 in psoriasis epidermis.

Conclusions: This study identifies the single-cell non-coding transcriptomic landscape of the psoriatic epidermis and highlights distinct lncRNA signatures in keratinocytes and immune cells, suggesting their involvement in pathogenic processes in psoriasis. 

Background

Despite the high morbidity and severe consequences of epidermolysis bullosa (EB), current treatments remain inadequate, lacking efficacy and the ability to target the microbial and inflammatory components of EB wounds. In this first-in-human open-label, single-arm study—part 3 of a 3-part Phase 1 clinical trial—we examined the safety, tolerability, and systemic exposure of topically applied TCP-25, a thrombin-derived C-terminal peptide with demonstrated anti-inflammatory, antimicrobial, and wound-healing properties in murine and porcine infection models.

Results

Five patients with inherited recessive dystrophic EB received TCP-25 gel, applied to a 50-cm² primary wound treatment area, which was compared with a reference wound treatment area which received standard wound care alone. TCP-25 gel was also applied to a 50-cm² secondary wound treatment area of a higher age or in a more complicated area. TCP-25 gel was administered at escalating doses of 7.25 mg, 14.5 mg, 21.5 mg, and 43.0 mg, 3 times per week over 4 consecutive 1-week treatment periods. For the primary safety endpoint, 11 adverse events were recorded, 10 unlikely related to treatment and mild or moderate in severity, with one possibly linked to gel adhesion. Additionally, no abnormal local reactions were observed in any wound treated with TCP-25, nor in any reference wound, compared to expected wound healing outcomes. For the secondary endpoint, we did not observe any systemic plasma uptake of TCP-25 in any participant. In an exploratory analysis, we observed a steady reduction in open wound size in TCP-25-treated primary wounds, culminating in a median reduction of 76% from baseline to Day 29. Reference wounds exhibited variable changes in wound size, including some increases in size at earlier time points. Secondary wounds that were treated with TCP-25 also decreased steadily, reaching a median open wound size reduction of 78% on day 29. Additionally, TCP-25 demonstrated potential efficacy in accelerating wound healing.

Conclusions

Topical TCP-25 gel was safe and well tolerated and showed no systemic uptake in patients with dystrophic EB, demonstrating promising effects on wound healing.

Psoriasis is a common chronic inflammatory skin disease determined by genetic and environmental factors, resulting in the activation of IL-23/IL-17-mediated immune response, epidermal hyperproliferation, and keratinocyte activation. Long non-coding RNAs (lncRNAs) are non-protein-coding transcripts > 500 nucleotides with diverse regulatory functions; their role in epidermal dysfunction in psoriasis is poorly understood. To identify epidermal transcripts with potential roles in psoriasis, including lncRNAs, we performed RNA sequencing on keratinocytes from psoriasis and healthy skin. We identified 889 differentially expressed lncRNAs, many of which with yet unknown functions. RP11-295G20.2 was identified as a lncRNA significantly induced in psoriasis keratinocytes, and this was verified by qRT-PCR and by single-molecule in situ hybridisation. Analysis of subcellular fractions of epidermis revealed a cytoplasmic localisation in line with results of single molecule in situ hybridisation. We report that RP11-295G20.2 has a skin-enriched expression, and within skin it is mainly expressed in suprabasal epidermal layers. Moreover, RP11-295G20.2 is induced by the key psoriasis cytokine IL-17A and shows a dynamic regulation during keratinocyte differentiation with upregulation during early differentiation and downregulation in the late stage. Knockdown of RP11-295G20.2 in keratinocytes promotes terminal differentiation. Based on our findings, we named RP11-295G20.2 Cytoplasmic Differentiation-Associated Epidermal RNA, CYDAER. In summary, our study provides a comprehensive characterisation of the non-coding RNA landscape of psoriasis keratinocytes and identifies CYDAER as a skin-enriched lncRNA regulating keratinocyte differentiation. Our data suggest that overexpression of CYDAER may contribute to altered differentiation in psoriatic epidermis.

Scalp psoriasis affects approximately 80% of patients with psoriasis and can negatively impact their quality of life. This post hoc analysis of the VOYAGE 2 Phase III randomized clinical trial evaluated scalp response to guselkumab treatment and its association with skin response and patient -reported outcomes. The study included patients with moderate -to -severe plaque psoriasis and baseline scalp psoriasis who were initially randomized to receive guselkumab. Patients were divided into 3 groups based on their achievement of a Psoriasis Area and Severity Index 90 response at week 28: responder continuation, non -responder continuation and responder withdrawal. In all 3 groups, mean Psoriasis Area and Severity Index head and scalpspecific Investigator's Global Assessment scores improved through week 28. In the responder withdrawal group, these scores worsened after treatment withdrawal at week 28, but remained stable through week 48 in both continuation groups. Trends in Dermatology Life Quality Index and Psoriasis Symptoms and Signs Diary itch scores mirrored those of mean scalp -specific Investigator's Global Assessment scores through week 48. Within -subject correlations were 0.83 between scalp -specific Investigator's Global Assessment and Psoriasis Area and Severity Index head scores and 0.78 between scalp -specific Investigator's Global Assessment and Psoriasis Symptoms and Signs Diary itch scores. Through week 252, Psoriasis Area and Severity Index head scores remained stable in the responder continuation group, improved in the non -responder continuation group and rapidly improved by week 84 in the responder withdrawal group after retreatment.

Single-cell technologies have become essential to driving discovery in both basic and translational investigative dermatology. Despite the multitude of available datasets, a central reference atlas of normal human skin, which can serve as a reference resource for skin cell types, cell states, and their molecular signatures, is still lacking. For any such atlas to receive broad acceptance, participation by many investigators during atlas construction is an essential prerequisite. As part of the Human Cell Atlas project, we have assembled a Skin Biological Network to build a consensus Human Skin Cell Atlas and outline a roadmap toward that goal. We define the drivers of skin diversity to be considered when selecting sequencing datasets for the atlas and list practical hurdles during skin sampling that can result in data gaps and impede comprehensive representation and technical considerations for tissue processing and computational analysis, the accounting for which should minimize biases in cell type enrichments and exclusions and decrease batch effects. By outlining our goals for Atlas 1.0, we discuss how it will uncover new aspects of skin biology.

Cutaneous squamous cell carcinoma (cSCC) is a fast-increasing cancer with metastatic potential. Extracellular vesicles (EVs) are small membrane-bound vesicles that play important roles in intercellular communication, particularly in the tumor microenvironment (TME). Here we report that cSCC cells secrete an increased number of EVs relative to normal human epidermal keratinocytes (NHEKs) and that interfering with the capacity of cSCC to secrete EVs inhibits tumor growth in vivo in a xenograft model of human cSCC. Transcriptome analysis of tumor xenografts by RNA-sequencing enabling the simultaneous quantification of both the human and the mouse transcripts revealed that impaired EV-production of cSCC cells prominently altered the phenotype of stromal cells, in particular genes related to extracellular matrix (ECM)-formation and epithelial-mesenchymal transition (EMT). In line with these results, co-culturing of human dermal fibroblasts (HDFs) with cSCC cells, but not with normal keratinocytes in vitro resulted in acquisition of cancer-associated fibroblast (CAF) phenotype. Interestingly, EVs derived from metastatic cSCC cells, but not primary cSCCs or NHEKs, were efficient in converting HDFs to CAFs. Multiplex bead-based flow cytometry assay and mass-spectrometry (MS)-based proteomic analyses revealed the heterogenous cargo of cSCC-derived EVs and that especially EVs derived from metastatic cSCCs carry proteins associated with EV-biogenesis, EMT, and cell migration. Mechanistically, EVs from metastatic cSCC cells result in the activation of TGFβ signaling in HDFs. Altogether, our study suggests that cSCC-derived EVs mediate cancer-stroma communication, in particular the conversion of fibroblasts to CAFs, which eventually contribute to cSCC progression.