P311 Promotes IL-4 Receptor‒Mediated M2 Polarization of Macrophages to Enhance Angiogenesis for Efficient Skin Wound Healing.

The transition from the proinflammatory phase to the prohealing phase in wound healing is essential for effective skin wound repair, which involves the balance of M1 and M2 polarization of wound-infiltrating macrophages. P311 plays an essential role in promoting wound closure by enhancing the biological function of epidermal stem cells, endothelial cells, and fibroblasts. Nevertheless, whether and how P311 regulates macrophage polarization remains unclear. In this study, we showed that P311 deficiency reduced the M2 polarization of macrophages, thereby attenuating the secretion of M2-like cytokines. The P311 deficiency prolonged the transition from the proinflammatory phase to the prohealing phase, accompanied by weakened angiogenesis and retarded granulation tissue formation, both of which coordinately hinder the healing of skin wounds. Mechanistically, P311 deficiency downregulated the expression of IL-4 receptor on macrophages, followed by less activation of the IL-4 receptor‒signal transducer and activator of transcription 6 signaling pathway, resulting in impaired M2 macrophage polarization. We further revealed that the mTOR signaling pathway was associated with the regulation of P311 on the expression of IL-4 receptor in macrophages. Thus, our study has highlighted the pivotal role of P311 in promoting the M2 polarization of macrophages for effective skin wound healing.

Analysis on the interactions between the first introns and other introns in mitochondrial ribosomal protein genes.

It is realized that the first intron plays a key role in regulating gene expression, and the interactions between the first introns and other introns must be related to the regulation of gene expression. In this paper, the sequences of mitochondrial ribosomal protein genes were selected as the samples, based on the Smith-Waterman method, the optimal matched segments between the first intron and the reverse complementary sequences of other introns of each gene were obtained, and the characteristics of the optimal matched segments were analyzed. The results showed that the lengths and the ranges of length distributions of the optimal matched segments are increased along with the evolution of eukaryotes. For the distributions of the optimal matched segments with different GC contents, the peak values are decreased along with the evolution of eukaryotes, but the corresponding GC content of the peak values are increased along with the evolution of eukaryotes, it means most introns of higher organisms interact with each other though weak bonds binding. By comparing the lengths and matching rates of optimal matched segments with those of siRNA and miRNA, it is found that some optimal matched segments may be related to non-coding RNA with special biological functions, just like siRNA and miRNA, they may play an important role in the process of gene expression and regulation. For the relative position of the optimal matched segments, the peaks of relative position distributions of optimal matched segments are increased during the evolution of eukaryotes, and the positions of the first two peaks exhibit significant conservatism.

In vitro and in vivo Evaluation of the Bioactive Nanofibers-Encapsulated Benzalkonium Bromide for Accelerating Wound Repair with MRSA Skin Infection.

Purpose: Developing the ideal drug or dressing is a serious challenge to controlling the occurrence of antibacterial infection during wound healing. Thus, it is important to prepare novel nanofibers for a wound dressing that can control bacterial infections. In our study, the novel self-assembled nanofibers of benzalkonium bromide with bioactive peptide materials of IKVAV and RGD were designed and fabricated. Methods: Different drug concentration effects of encapsulation efficacy, swelling ratio and strength were determined. Its release profile in simulated wound fluid and its cytotoxicity were studied in vitro. Importantly, the antibacterial efficacy, inhibition of biofilm formation effect and wound healing against MRSA infections in vitro and in vivo were performed after observing the tissue toxicity in vivo. Results: It was found that the optimized drug load (0.8%) was affected by the encapsulation efficacy, swelling ratio, and strength. In addition, the novel nanofibers with average diameter (222.0 nm) and stabile zeta potential (-11.2 mV) have good morphology and characteristics. It has a delayed released profile in the simulated wound fluid and good biocompatibility with L929 cells and most tissues. Importantly, the nanofibers were shown to improve antibacterial efficacy, inhibit biofilm formation, and lead to accelerated wound healing following infection with methicillin-resistant Staphylococcus aureus. Conclusion: These data suggest that novel nanofibers could effectively shorten the wound-healing time by inhibiting biofilm formation, which make it promising candidates for treatment of MRSA-induced wound infections.

A Modified Hyaluronic Acid-Based Dissolving Microneedle Loaded With Daphnetin Improved the Treatment of Psoriasis.

Psoriasis is a common chronic immune-inflammatory disease. Challenges exist in the present treatment of psoriasis, such as difficulties in transdermal drug administration and severe side effects. We hope to achieve a better therapeutic outcome for psoriasis treatment. By using modified soluble microneedles (MNs) loaded with daphnetin, the psoriasis symptoms of mice, the abnormal proliferation of keratinocytes, and the secretion of inflammatory factors were significantly reduced. In vitro, daphnetin is proven to inhibit the NF-κB signaling pathway and to inhibit the proliferation of HaCaT cells and the release of inflammatory factors, especially CCL20. This research showed that the modified microneedle loaded with daphnetin optimized transdermal drug delivery and relieved the symptoms of psoriasis more effectively. The novel route of Daph administration provides a future research direction for the treatment of psoriasis.

P311 Facilitates the Angiogenesis and Wound Healing Function of MSCs by Increasing VEGF Production.

As a potential clinical therapeutic cell for injured tissue repair, mesenchymal stem cells (MSCs) have attracted increasing attention. Enhancing the pro-healing function of MSCs has gradually become an essential topic in improving the clinical efficacy of MSCs. Recently, studies have shown that neuronal protein 3.1 (P311) plays a crucial role in promoting skin wound healing, suggesting P311 gene modification may improve the pro-healing function of MSCs. In this study, we demonstrated that increasing the in vivo expression of P311 could significantly enhance the ability of MSCs to lessen the number of inflammatory cells, increase the expression of IL10, reduce the levels of TNF-α and IFN-γ, increase collagen deposition, promote angiogenesis, and ultimately accelerate skin wound closure and improve the quality of wound healing. Importantly, we uncovered that P311 enhanced the pro-angiogenesis function of MSCs by increasing the production of vascular endothelial growth factor (VEGF) in vitro and in vivo. Mechanistically, we revealed that the mTOR signalling pathway was closely related to the regulation of P311 on VEGF production in MSCs. Together, our data displayed that P311 gene modification in MSCs augments their capabilities to promote skin wound closure, which might bring the dawn for its clinical application in the future.

Dendritic epidermal T cells secreting exosomes promote the proliferation of epidermal stem cells to enhance wound re-epithelialization.

BACKGROUND: Efficient re-epithelialization is important for successful skin wound healing. The proportion of epidermal stem cells (EpSCs) and dendritic epidermal T cells (DETCs) determines the extent of wound re-epithelialization, especially in large areas of skin tissue loss. However, it remains unknown whether and how DETCs regulate the status of EpSCs to impact wound re-epithelialization. METHODS: To investigate how DETCs regulate EpSCs in skin re-epithelialization, we utilized normal or full-thickness skin deficient wide type (WT) mice and Tcrσ knockout (Tcrσ-/-) mice with DETCs or DETCs-derived exosomes (Exos) treatment. Flow cytometry analysis (FCAS), BrdU labelled experiments, immunofluorescence and immunohistochemical assays were performed to detect the proportion of EpSCs in the epidermis. Wound closure rate and re-epithelialization were assayed by a macroscopical view and hematoxylin-eosin (H&E) staining. EpSCs in vitro were co-cultured with DETCs in a transwell-dependent or -independent manner, or supplement with GW4869 or Exos (5 µg/mL, 15 µg/mL and 45 µg/mL), and the proliferation of EpSCs was detected by means of FCAS and CFSE. RESULTS: Our data showed that the proportion of CD49fbriCD71dim cells, K15+ cells and BrdU+ cells in the normal epidermis of Tcrδ-/- mice had no significant difference compared to WT mice. For wounded Tcrδ-/- mice, DETCs treatment increase the proportion of CD49fbriCD71dim cells, K15+ cells and BrdU+ cells in the epidermis around the wound in comparison to PBS treatment. DETCs significantly increased the number of CD49fbriCD7dim cells and K15+ cells through transwell-dependent or -independent manners relative to control group. Furthermore, Exos stimuli remarkedly promote the proliferation of EpSCs compared to control group, while the increasement was suppressed when DETCs were interfered with GW4869. Gross observation and H&E staining showed that Exos significantly accelerated wound closure and increased re-epithelialization length in Tcrδ-/- mice when compared to control mice. Additionally, we found in vivo that Exos observably facilitated the proliferation of CD49fbriCD7dim cells and K15+ cells. CONCLUSIONS: We revealed that DETCs enhanced the proliferation of EpSCs in the epidermis around the wounds to accelerate re-epithelialization in which Exos played important roles in the remote regulation of EpSCs proliferation. Together, these findings suggest a mechanistic link among DETC-derived exosomes, the proliferation of EpSCs, and wound re-epithelialization in the skin.

Histatin 1 enhanced the speed and quality of wound healing through regulating the behaviour of fibroblast.

OBJECTIVES: Histatin 1(Hst 1) has been proved to promote wound healing. However, there was no specific study on the regulation made by Hst 1 of fibroblasts in the process of wound healing. This research comprehensively studied the regulation of Hst 1 on the function of fibroblasts in the process of wound healing and preliminary mechanism about it. MATERIALS AND METHODS: The full-thickness skin wound model was made on the back of C57/BL6 mice. The wound healing, collagen deposition and fibroblast distribution were detected on days 3, 5 and 7 after injury. Fibroblast was cultured in vitro and stimulated with Hst 1, and then, their biological characteristics and functions were detected. RESULTS: Histatin 1 can effectively promote wound healing, improve collagen deposition during and after healing and increase the number and function of fibroblasts. After healing, the mechanical properties of the skin also improved. In vitro, the migration ability of fibroblasts stimulated by Hst 1 was significantly improved, and the fibroblasts transformed more into myofibroblasts, which improved the function of contraction and collagen secretion. In fibroblasts, mTOR signalling pathway can be activated by Hst 1. CONCLUSIONS: Histatin 1 can accelerate wound healing and improve the mechanical properties of healed skin by promoting the function of fibroblasts. The intermolecular mechanisms need to be further studied, and this study provides a direction about mTOR signalling pathway.

Critical new insights into the interactions of hexafluoropropylene oxide-dimer acid (GenX or HFPO-DA) with albumin at molecular and cellular levels.

A key characteristic to be elucidated, to address the harmful health risks of environmental perfluorinated alkyl substances (PFAS), is their binding modes to serum albumin, the most abundant protein in blood. Hexafluoropropylene oxide-dimer acid (GenX or HFPO-DA) is a new industrial replacement for the widespread linear long-chain PFAS. However, the detailed interaction of new-generation short-chain PFAS with albumin is still lacking. Herein, the binding characteristics of bovine serum albumin (BSA) to GenX were explored at the molecular and cellular levels. It was found that this branched short-chain GenX could bind to BSA with affinity lower than that of legacy linear long-chain perfluorooctanoic acid (PFOA). Site marker competitive study and molecular docking simulation revealed that GenX interacted with subdomain IIIA to form BSA-GenX complex. Consistent with its weaker affinity to albumin protein, the cytotoxicity of branched short-chain GenX was less susceptible to BSA binding compared with that of the linear long-chain PFOA. In contrast to the significant effects of strong BSA-PFOA interaction, the weak affinity of BSA-GenX binding did not influence the structure of protein and the cytotoxicity of GenX. The detailed characterization and direct comparisons of serum albumin interaction with new generation short-chain GenX will provide a better understanding for the toxicological properties of this new alternative.