Wnt4 increases the thickness of the epidermis in burn wounds by activating canonical Wnt signalling and decreasing the cell junctions between epidermal cells

Electrospun PLGA/PCL Nanofiber Film Loaded with LPA Promotes Full-Layer Wound Healing by Regulating the Keratinocyte Pyroptosis

Electrospun nanofibers have a number of qualities that make them a suitable choice for skin wound healing. Lysophosphatidic acid (LPA) stimulates the keratinocytes and fibroblasts to proliferate, differentiate, and migrate and enhances skin wound healing. Here, we developed the electrospun scaffolds contained in polycaprolactone (PCL) and polylactic-co-glycolic acid (PLGA). The scaffolds loaded with LPA nanoparticles retained a porous nanofiber structure and showed better physicochemical properties and biocompatibility. The scaffold continuously releases LPA to quickly initiate cell signaling and maintain long-term anti-inflammatory activity. In this study, we found that PP scaffold with LPA reduces the disordered collagen deposition and the thickness of the newborn epidermis, improves skin healing, and reduces scar formation. Explaining the mechanism of LPA mineralized tissue regeneration in skin wound healing, LPA inhibited the pyroptosis of keratinocyte, a cell death process that induces inflammation and scar formation by inhibiting the expression of TNF-α and β-catenin proteins. Thus, the electrospun PP scaffold with LPA can be potentially developed as a therapeutic avenue to target skin wound healing.

Ferroptosis: A New Strategy for the Treatment of Fibrotic Diseases

Ferroptosis is a new type of cell death characterized by iron dependence and the excessive accumulation of lipid reactive oxygen species (lipid ROS) that has gradually become better characterized. There is sufficient evidence indicating that ferroptosis is associated with a variety of human life activities and diseases, such as tumor suppression, ischemic organ injury, and degenerative disorders. Notably, ferroptosis is also involved in the initiation and development of fibrosis in various organs, including liver fibrosis, pulmonary fibrosis, renal fibrosis, and cardiac fibrosis, which is usually irreversible and refractory. Although a large number of patients with fibrosis urgently need to be treated, the current treatment options are still limited and unsatisfactory. Organ fibrosis involves a series of complex and orderly processes, such as parenchymal cell damage, recruitment of inflammatory cells and activation of fibroblasts, which ultimately leads to the accumulation of extracellular matrix (ECM) and the formation of fibrosis. An increasing number of studies have confirmed the close association between these pathological processes and ferroptosis. This review summarizes the role and function of ferroptosis in fibrosis and proposes several potential therapeutic strategies and pathways based on ferroptosis.

HMGB1 Accelerates Wound Healing by Promoting the Differentiation of Epidermal Stem Cells via the "HMGB1-TLR4-Wnt/Notch" Axis

Objective: Impairments in the differentiation and migratory capacity of epidermal stem cells (ESCs) are pivotal factors contributing to delayed wound healing. High mobility group box1 (HMGB1) has recently emerged as a potential target for tissue repair. Therefore, we aimed to investigate the role and molecular mechanisms of HMGB1 in ESCs during the wound-healing process. Approach: Initially, we examined the expression of HMGB1 and the differentiation of ESCs in normal skin, normal wounds and chronic wounds. Then, we assessed the ESC migration and differentiation, and the key markers in the Wnt/Notch signaling pathways, after treatment of HMGB1 and inhibitor, and the knockdown of toll-like receptor 4 (TLR4), using scratch assay, qPCR, western blotting, and immunofluorescence. Finally, we conducted mice models to analyze the healing rates and quality in vivo. Results: HMGB1 was decreased across all epidermal layers, and the differentiation of ESCs was hindered in diabetic foot ulcer. In vitro, HMGB1 enhanced both the migration and differentiation of ESCs while stimulating the expression of the Wnt/Notch pathway within ESCs. However, the downregulation of TLR4 negated these effects. Finally, our in vivo experiments provided evidence that HMGB1 facilitates wound healing and epidermis differentiation via TLR4 and Wnt/Notch signaling pathways. Innovation: This study innovatively introduces HMGB1 as a novel target for skin wound healing and elucidates its mechanisms of action. Conclusions: HMGB1 accelerated wound healing by promoting the differentiation of epidermal stem cells through the "HMGB1-TLR4-Wnt/Notch" axis, which reveals a new potential mechanism and target to expedite wound healing.

Characterization of Cell Type Abundance and Gene Expression Timeline from Burned Skin Bulk Transcriptomics by Deconvolution

Currently, no timeline of cell heterogeneity in thermally injured skin has been reported. In this study, we proposed an approach to deconvoluting cell type abundance and expression from skin bulk transcriptomics with cell type signature matrix constructed by combining independent normal skin and peripheral blood scRNA-seq datasets. Using CIBERSORTx group mode deconvolution, we identified perturbed cell type fractions and cell type-specific gene expression in three stages postthermal injury. We found an increase in cell proportions and cell type-specific gene expression perturbation of neutrophils, macrophages, and endothelial cells and a decrease in CD4+ T cells, keratinocytes, melanocyte, and fibroblast cells, and cell type-specific gene expression perturbation postburn injury. Keratinocyte, fibroblast, and macrophage up regulated genes were dynamically enriched in overlapping and distinct Gene Ontology biological processes including acute phase response, leukocyte migration, metabolic, morphogenesis, and development process. Down-regulated genes were enriched in Wnt signaling, mesenchymal cell differentiation, gland and axon development, epidermal morphogenesis, and fatty acid and glucose metabolic process. We noticed an increase in the expression of CCL7, CCL2, CCL20, CCR1, CCR5, CCXL8, CXCL2, CXCL3, MMP1, MMP8, MMP3, IL24, IL6, IL1B, IL18R1, and TGFBR1 and a decrease in expression of CCL27, CCR10, CCR6, CCR8, CXCL9, IL37, IL17, IL7, IL11R, IL17R, TGFBR3, FGFR1-4, and IGFR1 in keratinocytes and/or fibroblasts. The inferred timeline of wound healing and CC and CXC genes in keratinocyte was validated on independent dataset GSE174661 of purified keratinocytes. The timeline of different cell types postburn may facilitate therapeutic timing.