Severe Burn Injury Significantly Alters the Gene Expression and m6A Methylation Tagging of mRNAs and lncRNAs in Human Skin.

N6-methyladenosine (m6A) modulates RNA metabolism and functions in cell differentiation, tissue development, and immune response. After acute burns, skin wounds are highly susceptible to infection and poor healing. However, our understanding of the effect of burn injuries on m6A methylation and their potential mechanism is still limited. Human m6A-mRNA&lncRNA Epitranscriptomic microarray was used to obtain comprehensive mRNA and lncRNA transcriptome m6A profiling and gene expression patterns after burn injuries in human skin tissue. Bioinformatic and functional analyses were conducted to find molecular functions. Microarray profiling showed that 65 mRNAs and 39 lncRNAs were significantly hypermethylated; 5492 mRNAs and 754 lncRNAs were significantly hypomethylated. Notably, 3989 hypomethylated mRNAs were down-expressed and inhibited many wound healing biological processes and pathways including in the protein catabolic process and supramolecular fiber organization pathway; 39 hypermethylated mRNAs were up-expressed and influenced the cell surface receptor signaling pathway and inflammatory response. Moreover, we validated that m6A regulators (METTL14, METTL16, ALKBH5, FMR1, and HNRNPC) were significantly downregulated after burn injury which may be responsible for the alteration of m6A modification and gene expression. In summary, we found that homeostasis in the skin was disrupted and m6A modification may be a potential mechanism affecting trauma infection and wound healing.

miR-24-3p obstructs the proliferation and migration of human skin fibroblasts after thermal injury by targeting PPAR-ß and positively regulated by NF-κB.

Thermal injury repair is a complex process during which the maintenance of the proliferation and migration of human skin fibroblasts (HSFs) exert a crucial role. MicroRNAs have been proven to exert an essential function in repairing skin burns. This study delves into the regulatory effects of miR-24-3p on the migration and proliferation of HSFs that have sustained a thermal injury, thereby, providing deeper insight into thermal injury repair pathogenesis. The PPAR-ß protein expression level progressively increased in a time-dependent manner on the 12th, 24th and 48th hour following the thermal injury of the HSFs. The knockdown of PPAR-ß markedly suppressed the proliferation of and migration of HSF. Following thermal injury, the knockdown also promoted the inflammatory cytokine IL-6, TNF-α, PTGS-2 and P65 expression. PPAR-ß contrastingly exhibited an opposite trend. A targeted relationship between PPAR-ß and miR-24-3p was predicted and verified. miR-24-3p inhibited thermal injured HSF proliferation and migration and facilitated inflammatory cytokine expression through the regulation of PPAR-ß. p65 directly targeted the transcriptional precursor of miR-24 and promoted miR-24 expression. A negative correlation between miR-24-3p expression level and PPAR-ß expression level in rats' burnt dermal tissues was observed. Our findings reveal that miR-24-3p is conducive to rehabilitating the denatured dermis, which may be beneficial in providing effective therapy of skin burns.

Integrated analysis of tRNA-derived small RNAs reveals new therapeutic genes of hyperbaric oxygen in diabetic foot ulcers.

Background: To reveal the alterations of tRNA-derived small RNA (tsRNA) expression profiles induced by hyperbaric oxygen (HBO) treatment in diabetic foot ulcers (DFUs) and investigate new therapeutic targets. Materials & methods: tsRNA sequencing was employed in normal skin tissue, in DFUs, and after HBO treatment groups. A quantitative real-time PCR was used to validate tsRNA sequencing results and their targets levels. Bioinformatics analysis was performed to reveal their therapeutic functions in DFUs. Results: A total of 22 tsRNAs were differentially expressed in the three groups. Three selected tsRNAs were validated by quantitative real-time PCR for further analysis, which were all significantly overexpressed in DFU while being normally expressed after HBO treatment. Bioinformatics analysis disclosed that these tsRNAs may play therapeutic roles through the regulation of the Wnt signaling pathway. Conclusion: tsRNAs may be novel useful targets for HBO to treat DFUs.

Long noncoding RNA GAS5 accelerates diabetic wound healing and promotes lymphangiogenesis via miR-217/Prox1 axis.

BACKGROUND: Diabetes is usually the leading cause of chronic non-healing wounds. LncRNA-GAS5 has been verified to be involved in the regulation of diabetes or high glucose (HG)-stimulated cells. However, its regulatory roles in diabetic wound healing need further investigation. METHOD: GAS5, miR-217 and Prox1 were identified by qRT-PCR. MTT, flow cytometry assay, wound-healing assay and tube formation were used to analyze cell viability, apoptosis, migration and tube formation capacity. Western blotting was carried out to detect the protein expression of c-Myc, CyclinD1, CDK4, Bcl-2, Prox1, VEGFR-3 and LYVE-1. Bioinformatics and luciferase assay were performed to predict and validate the binding sites of miR-217 on GAS5 and Prox1. Immunofluorescence staining detected the expression and distribution of Prox1. The wound healing rate was also assessed by setting up the diabetic mouse model. H&E staining assessed the distribution of inflammatory cells and fibroblasts in the wound tissues. RESULTS: GAS5 was significantly down-regulated whereas miR-217 was obviously up-regulated in diabetic skin, HG-induced lymphatic endothelial cells (LECs) and diabetic mouse model. GAS5 sponged miR-217 to up-regulate Prox1. GAS5 overexpression or miR-217 inhibition rescued the impairments of cell viability, migration and lymphatic vessel formation and the facilitation of apoptosis of LECs caused by HG. Similar impacts were observed on the protein level of VEGFR-3, LYVE-1, and Prox1. GAS5 promoted wound healing and lymphangiogenesis in the diabetic mouse model. CONCLUSION: GAS5 sponged miR-217 to up-regulate Prox1 and promote lymphangiogenesis and diabetic wound healing. This might provide novel therapeutic strategy to improve the efficacy of diabetic wound healing.

LINC00470 accelerates the proliferation and metastasis of melanoma through promoting APEX1 expression.

Recently studies found that APEX1 was abnormally expressed in melanoma, indicating that it might be involved in the development of melanoma. However, the underlying mechanism and the interaction between APEX1 and LINC00470 in melanoma are not clear. Therefore, we aimed to investigate the role of LINC00470 in the development of melanoma in this work. We discovered that LINC00470 was overexpressed in melanoma tissues and cells compared with the adjacent normal tissues and cells by qPCR. The overexpression of LINC00470 promoted the proliferation and migration of melanoma cells. The functional investigation demonstrated that LINC00470 activated the transcription factor, ZNF131, to regulate the APEX1 expression, which finally promoted cell proliferation and migration. In contrast, knockdown of LINC00470 could significantly inhibit the melanoma cell proliferation and migration, and suppress the growth of tumor in vivo. Overexpression of APEX1 could reverse the impact of the silence of LINC00470 in melanoma cells. In summary, our studies revealed that LINC00470 promoted melanoma proliferation and migration by enhancing the expression of APEX1, which indicated that LINC00470 might be a therapeutic target for the treatment of melanoma.

Hyperbaric oxygen potentiates diabetic wound healing by promoting fibroblast cell proliferation and endothelial cell angiogenesis.

BACKGROUND: Diabetic foot ulcer (DFU), one of the diabetic complications, brings high burden to diabetic patients. Hyperbaric oxygen therapy (HBOT) has been proven to be an effective clinical method for the treatment of DFU. However, the mechanisms still to be elucidated. METHODS: Diabetic foot mice model was established, and treated with hyperbaric oxygen. Haematoxylin & eosin (H&E) staining and Masson's trichrome staining were used for the analysis of wound healing. Human skin fibroblast (HSF) and human umbilical vein endothelial cell (HUVECS) were exposed to high glucose and hyperbaric oxygen for studying the mechanism of hyperbaric oxygen promoted wound healing in vitro. Wound healing assay, reactive oxygen species (ROS) assay, cell proliferation assay and tube formation assay were used for the analysis of wound healing. Quantitative-polymerase chain reaction (Q-PCR), Western blotting and enzyme-linked immunosorbent assay (ELISA) were used for the analysis of gene expression. RESULTS: HBOT facilitated wound healing in DFU mice model, and promoted the expression of HIF-1α, NF-κB, VEGFA, SDF-1, VEGFR2 and CXCR4. Hyperbaric oxygen promoted the proliferation, migration and ROS production, as well as the expression of SDF-1 and VEGFA in HSF. HBOT stimulated the proliferation, migration and tube formation, as well as the expression of CXCR4 and VEGFR2 in HUVECS. CONCLUSION: Hyperbaric oxygen potentiates angiogenesis and diabetic wound healing by activating HIF-1α signaling, so as to promote the expression of VEGF/SDF-1 in HSF and the expression of VEGFR/CXCR4 in HUVECS, ultimately to promote the proliferation of HSF and the angiogenesis of HUVECS.

linc00174-EZH2-ZNF24/Runx1-VEGFA Regulatory Mechanism Modulates Post-burn Wound Healing.

Preservation of denatured dermis exerts promotive functions in wound healing and improves the appearance and function of skin. Angiogenesis is crucial for wound healing during burn injury. However, the potential molecular mechanism of angiogenesis in the recovery after burn injury remains to be elucidated. Herein, RNA chromatin immunoprecipitation (ChIP) sequencing analysis revealed upregulation of long intergenic non-coding RNA 00174 (linc00174) in the post-burn tissues. linc00174 overexpression promoted angiogenic activities of human umbilical vein endothelial cells (HUVECs) in the heat-denatured cell model, characterized by the promotion of cell proliferation, migration, and tube formation. Mechanistically, linc00174 directly bound to enhancer of zeste homolog 2 (EZH2), thus stimulating the protein level of trimethylation at lysine 27 of histone H3 (H3K27me3). Moreover, inhibition of EZH2 resulted in downregulation of ZNF24 and Runx1, as well as a decline of vascular endothelial growth factor A (VEGFA). Furthermore, EZH2 modulated epigenetic repression of ZNF24 and Runx1 through the promoter of H3K27me3. Additionally, ZNF24 and Runx1 both functioned as transcriptional inhibitors of VEGFA. Taken together, these findings uncover that linc00174 epigenetically inhibits ZNF24 and Runx1 expression through binding to EZH2, thus attenuating the suppression of VEGFA, contributing to the facilitation of angiogenesis during the recovery of heat-denatured endothelial cells.

Reconstruction of fingers after electrical injury using lateral tarsal artery flap.

OBJECTIVE: Electrical injuries to the fingers account for the majority of total severe burns that occur each year. While several types of flaps have been used in covering finger defects, all have limitations or disadvantages. The purpose of this study was to introduce our clinical experiences of using the lateral tarsal artery (LTA) flap to successfully restore fingers after electrical injury. PATIENTS AND METHODS: From 2005 to 2012, 10 patients with 14 severe electrical burns to their fingers, including six thumbs and four index and four middle fingers, were treated with LTA flap. The wound size ranged from 2.0×3.0 cm to 3.5×5.0 cm. The flap with free tendon graft was used to repair the tendon defect in four cases, free nerve graft was used to repair the feeling defect in two cases, and the flap with nerve was used to repair the feeling defect in two cases. All the patients were followed up for 3 months to 2 years. RESULTS: All skin flaps adhered successfully and there were no complications. All patients were satisfied with the esthetic appearance and functional outcome of the finger reconstruction. CONCLUSION: LTA flap is a reliable method to restore fingers after severe electrical injuries.

[Repair of large and deep skin and soft tissue defects around the knee joints with free latissimus dorsi musculocutaneous flaps].

OBJECTIVE: To investigate the clinical efficacy of free latissimus dorsi musculocutaneous flaps in repairing large and deep skin and soft tissue defects around the knee joints. METHODS: Twenty-five patients with large and deep skin and soft tissue defects around the knee joints were hospitalized from March 2005 to March 2014. The area of defects around the knee joints ranged from 10 cm × 8 cm to 43 cm × 23 cm. The free latissimus dorsi musculocutaneous flaps were used to repair the defects, with the area ranging from 12 cm × 10 cm to 45 cm × 25 cm. The thoracodorsal artery and its concomitant vein of the musculocutaneous flap were anastomosed to the descending branch of the lateral circumflex femoral artery and its concomitant vein respectively to reconstruct blood supply. Split-thickness skin grafts around the flap donor sites were harvested to cover the muscle surface of the musculocutaneous flaps. The flap donor sites were closed directly with suture, and the skin donor sites were healed by dressing change. RESULTS: All the 25 flaps survived without vascular crisis. The flaps were in satisfactory appearance. The flap donor sites were healed with linear scar. All the patients were followed up for 3 to 6 months. At last, they were able to stand up and walk. CONCLUSIONS: The free latissimus dorsi musculocutaneous flap transplantation is an effective treatment for the repair of large and deep soft tissue defects around the knee joints, and the descending branch of lateral circumflex femoral artery and its concomitant vein are the appropriate recipient vessels.