Identification of potential diagnostic biomarkers and immune infiltration features in diabetic foot ulcer by bioinformatics analysis and validation.

Diabetic foot ulcer (DFU) is the most serious and costly chronic complication that may lead to disability and even death in patients suffering from diabetes mellitus (DM). However, the clinical diagnosis and prognosis of DFU is inadequate. There is still a lack of effective biomarkers for its early diagnosis. We obtained the circRNA expression dataset GSE114248 and mRNA expression dataset GSE80178 from the GEO. R software was used to identify the differentially expressed circRNAs (DECs). The mRNAs associated with DFU were identified by a random forest algorithm and intersected with mRNAs predicted by circRNAs. Then, the circRNA-miRNA-mRNA network was established and the hub genes were screened using GO semantic similarity and were validated by the GSE199939 dataset. Meanwhile, the expression level of the biomarkers was verified by RT-PCR assays and immunohistochemistry. Finally, GSEA was conducted to determine differential immune cell infiltration and the immunological cells' relationships with hub genes. We identified three hub genes including KIAA1109, ENPP5, and NRP1 that might play an important role in DFU. ROC curve results also showed a good performance of these three genes in the validation dataset. Furthermore, RT-PCR assays and immunohistochemistry confirmed the results above. Immune infiltration analysis indicated that DFU had a significant increase in Neutrophils. Moreover, three hub genes were closely correlated with a variety of inflammatory cells. KIAA1109, ENPP5, and NRP1 are key hub genes of DFU. They might play an important role in the development of DFU and could be potential biomarkers in DFU.

MicroRNA miR-145-5p Inhibits Cutaneous Wound Healing by Targeting PDGFD in Diabetic Foot Ulcer.

Diabetic foot ulcer (DFU) is one major, common and serious chronic complication of diabetes mellitus, which is characterized by high incidence, high risk, high burden, and high treatment difficulty and is a leading cause of disability and death in patients with diabetes. Long-term hyperglycemia can result in cellular dysfunction of fibroblasts, which play pivotal roles in wound healing. MicroRNAs (miRNAs) were reported to mediate the pathological processes of multiple diseases, including diabetic wound healing. This research aimed to investigate the functional role of miR-145-5p in high-glucose (HG)-exposed fibroblasts and in DFU mouse models. Human foreskin fibroblast cells (HFF-1) were stimulated by HG to induce cell injury. MiR-145-5p level in HG-stimulated HFF-1 cells was detected via RT-qPCR. The binding between miR-145-5p and PDGFD was validated by Luciferase reporter assay. The effects of the miR-145-5p/PDGFD axis on the viability, migration, and apoptosis of HG-exposed HFF-1 cells were determined by CCK-8, wound healing, and flow cytometry assays. DFU mouse models were subcutaneously injected at the wound edges with miR-145-5p inhibitor/mimics. Images of the wounds were captured on day 0 and 8 post-injection, and wound samples were collected after mice were sacrificed for histological analysis by H&E staining. HG decreased cell viability and increased miR-145-5p expression in HFF-1 cells in a dose- and time-dependent manner. MiR-145-5p downregulation promoted cell viability and migration and inhibited cell apoptosis of HG-stimulated HFF-1 cells, while miR-145-5p overexpression exerted an opposite effect on cell viability, migration, and apoptosis. PDGFD was a direct target gene of miR-145-5p, whose silencing reversed the influence of miR-145-5p downregulation on HG-induced cellular dysfunction of HFF-1 cells. Additionally, downregulating miR-145-5p facilitated while overexpressing miR-145-5p inhibited wound healing in DFU mouse models. MiR-145-5p level was negatively associated with PDGFD level in wound tissue samples of DFU mouse models. MiR-145-5p inhibition improves wound healing in DFU through upregulating PDGFD expression.

Effects of Moist Exposed Burn Therapy and Ointment (MEBT/MEBO) on the autophagy mTOR signalling pathway in diabetic ulcer wounds.

Context: Burn therapy (MEBT)/moist exposed burn ointment (MEBO) is an effective traditional Chinese medicine method to treat diabetic wound, but the mechanism is unclear. Autophagy has been proved to be closely related with wound healing, so MEBO/MEBT is hypothesized to promote diabetic wound healing by regulating autophagy.Objective: To explore the mechanism of moist exposed MEBT/MEBO promoting diabetic wound repair.Materials and methods: Eighty male Wistar rats were randomly assigned to control (n = 20) and diabetic group induced by intraperitoneal injection of STZ (n = 60), which were further randomly assigned to MEBO, Kangfuxin and model groups (n = 20 each). All rats underwent full-thickness skin resection in the back. Wound healing was dynamically observed and wound tissues were collected at five time points for pathological examination, autophagosome and the expression of PI3K, Akt and mTOR.Results: The healing time in the control group was the shortest, no statistically significant difference was found between the MEBO and the Kangfuxin group (p = 0.76). The morphology of autophagosomes ranged large to small, which was the most obvious in the MEBO group. The mRNA and protein expression of PI3K, Akt and mTOR in each group reached the peak on Day 5, the levels in the MEBO group were the highest (F = 18.43, 19.97, 15.36, p < 0.05). On Day 11, the expression levels in each group began to decline.Discussion and conclusions: In this study, we discussed the molecular mechanism of MEBT/MEBO promoting the repair of diabetic ulcer wounds through autophagy and PI3K-Akt-mTOR signalling pathway, which provides a new way for drug design in the future.

Bone transport induces the release of factors with multi-tissue regenerative potential for diabetic wound healing in rats and patients.

Tibial cortex transverse distraction is a surgical method for treating severe diabetic foot ulcers (DFUs), but the underlying mechanism is unclear. We show that antioxidant proteins and small extracellular vesicles (sEVs) with multiple-tissue regenerative potential are released during bone transport (BT) in humans and rats. These vesicles accumulate in diabetic wounds and are enriched with microRNAs (miRNAs) (e.g., miR-494-3p) that have high regenerative activities that improve the circulation of ischemic lower limbs while also promoting neovascularization, fibroblast migration, and nerve fiber regeneration. Deletion of miR-494-3p in rats reduces the beneficial effects of BT on diabetic wounds, while hydrogels containing miR-494-3p and reduced glutathione (GSH) effectively repair them. Importantly, the ginsenoside Rg1 can upregulate miR-494-3p, and a randomized controlled trial verifies that the regimen of oral Rg1 and GSH accelerates wound healing in refractory DFU patients. These findings identify potential functional factors for tissue regeneration and suggest a potential therapy for DFUs.

Role of Autophagy and Apoptosis in Aluminum Exposure-Induced Liver Injury in Rats.

Aluminum (Al) exposure can lead to different degrees of damage to various organ systems of the body. It has been previously revealed that Al exposure can damage the liver, causing liver dysfunction. However, the specific mechanism remains unclear. This research aims to uncover the damaging effect of Al exposure on rat liver and to demonstrate the role of autophagy and apoptosis in this effect. Thirty-two Wistar rats were randomly divided into the control group (C group), low-dose Al exposure group (L group), middle-dose Al exposure group (M group), and high-dose Al exposure group (H group) (n = 8). The rats, respectively, received intraperitoneal injections of 0, 5, 10, and 20 mg/kg·day AlCl3 solution for 4 weeks (5 times/week). After the experiment, changes in the ultrastructure and autolysosome in rat liver were observed; the liver function, apoptosis rate, as well as levels of apoptosis-associated proteins and autophagy-associated proteins were detected. The results indicated that Al exposure damaged rat liver function and structure and resulted in an increase in autolysosomes. TUNEL staining revealed an elevated number of apoptotic hepatocytes after Al exposure. Moreover, we found from Western blotting that the levels of autophagy-associated proteins Beclin1 and LC3-II were increased; apoptotic protein Caspase-3 level was elevated and the Bcl-2/Bax ratio was reduced. Our research suggested that Al exposure can lead to high autophagy and apoptosis levels of rat hepatocytes, accompanied by hepatocyte injury and impaired liver function. This study shows that autophagy and apoptosis pathways participate in Al toxication-induced hepatocyte injury.

A Lower IL-34 Expression Is Associated With Non-Healing Diabetic Foot Ulcers.

BACKGROUND: The non-healing of DFU is a major cause of high disability, morbidity, and mortality. Thus, new therapeutic targets and methods to help healing in patients with DFUs are major research hotspots. OBJECTIVE: This study examined the molecular differences between healing and non-healing DFUs to identify genes associated with diabetic foot ulcers (DFU) healing. METHODS: Differentially expressed genes (DEGs) were identified by bioinformatics. Samples were collected from patients with healing(n=10) and non-healing(n=10) DFUs from September 2021 to September 2022. IL-34 expression was measured by ELISA and qRT-PCT. The fibroblasts from healing and non-healing DFU were divided according to their gene signatures and subdivided based on their gene expression profile differences. RESULTS: A comparison of fibroblast subpopulation characteristics revealed that the proportion of subpopulation 4 was significantly higher in non-healing DFUs than in healing DFUs. Subpopulation 4 had 254 upregulated genes and 2402 downregulated genes in the non-healing compared with the healing DFUs. The DEGs were involved in several biological functions, including cytokine activity, receptor-ligand activity, signaling receptor activator activity, and receptor regulator activity. IL-34 was downregulated in non-healing compared with healing DFUs, suggesting a possible role of IL-34 in DFU healing. In the clinical specimens, IL-34 was significantly downregulated in non-healing DFUs, consistent with the bioinformatics results. CONCLUSION: IL-34 expression is downregulated in non-healing DFU. IL-34 appears to be involved in DFU healing, but the exact causal relationship remains to be explored.

Effects of Intensive Glycemic Control on Serum Exosome miR-126-3p and miR-125b-1-3p Levels and Wound Healing in Patients with Diabetic Ulcers.

Objective: Intensive glycemic control and exosomal miRNAs have both been reported to improve wound repair in diabetic ulcers. In this study, we aimed to investigate the effects of intensive glycemic control on serum exosome microRNA-126-3p (miR-126-3p), microRNA-125b-1-3p (miR-125b-1-3p), and wound healing in patients with diabetic ulcers. Methods: Herein, 45 diabetic patients with an ulcer, aged 35-75 years old, were randomly assigned to the intensive glycemic control group (n = 21) and the conventional glycemic control group (n = 24). Serum exosomes were extracted in the laboratory and assessed by Western blotting, transmission electron microscopy, and nanoparticle tracking analysis. The expression of miR-126-3p and miR-125b-1-3p was validated using quantitative real-time polymerase chain reaction. The wound healing of each diabetic ulcer patient was measured and imaged; additionally, clinical and follow-up data were collected. Finally, the clinical and laboratory data were combined for statistical analysis. Results: Intensive glycemic control was significantly more conducive to wound healing and infection control than conventional glycemic control (P < 0.05). Serum exosomal miR-126-3p was negatively correlated with fasting plasma glucose levels (r = 0.34, P < 0.05) and positively associated with the wound healing rate (r = 0.45, P < 0.01). The level of miR-126-3p in the intensive glycemic control group was significantly higher than that in the conventional glycemic control group (P < 0.01). Serum exosomal miR-125b-1-3p was not correlated with blood glucose levels (r = 0.03, P > 0.05) and was positively associated with the wound healing rate (r = 0.33, P < 0.05). No significant difference was observed in the level of miR-125b-1-3p between the intensive and conventional glycemic control groups. Regarding the prognosis of diabetic ulcers, the intensive glycemic control group was better than the conventional group (Z = -2.02, P < 0.05). Conclusion: Serum exosome (miR-125b-1-3p and miR-126-3p) levels are correlated with wound healing in diabetic ulcers. Intensive glycemic control increases the serum exosomal miR-126-3p level, which might be one of the mechanisms that promotes wound healing in diabetic ulcers.

Identifying potential pathogenesis and immune infiltration in diabetic foot ulcers using bioinformatics and in vitro analyses.

BACKGROUND: Diabetic foot ulcers (DFU) are among the fastest-growing diseases worldwide. Recent evidence has emphasized the critical role of microRNA (miRNA)-mRNA networks in various chronic wounds, including DFU. In this study, we aimed to clarify the miRNA-mRNA axes associated with the occurrence of DFU. METHODS: Expression profiles of miRNAs and mRNAs were extracted from the Gene Expression Omnibus. Differentially expressed genes and differentially expressed miRNAs were identified, and miRNA-mRNA regulatory axes were constructed through integrated bioinformatics analyses. We validated the miRNA-mRNA axes using quantitative real-time PCR (qPCR) and dual-luciferase reporter assays. We conducted an immune infiltration analysis and confirmed the bioinformatics results using immunofluorescence staining. Single-sample gene set enrichment analysis (ssGSEA) was used to analyze the metabolic mechanisms. RESULTS: miR-182-5p-CHL1/MITF and miR-338-3p-NOVA1 interactions were identified using in silico analysis. The qPCR results showed apparent dysregulation of these miRNA-mRNA axes in DFU. The dual-luciferase reporter assay confirmed that miR-182-5p targeted CHL1 and MITF, and miR-338-3p targeted NOVA1. We conducted an immune infiltration analysis and observed that key genes correlated with decreased infiltration of M1 macrophages and resting mast cells in DFU. Immunofluorescence staining verified the co-localization of CHL1 and tryptase, while MITF and CD68 showed weak positive correlations. Metabolic pathways related to these three genes were identified using ssGSEA. CONCLUSIONS: In summary, the miR-182-5p-CHL1/MITF and miR-338-3p-NOVA1 pathway interactions and decreased infiltration of M1 macrophages and resting mast cells may provide novel clues to the pathogenesis of DFU. TRIAL REGISTRATION: The clinical trial included in this study was registered in the Chinese Clinical Trial Registry ( ChiCTR2200066660 ) on December 13, 2022.

IL-1B can serve as a healing process and is a critical regulator of diabetic foot ulcer.

Background: Diabetic foot ulcer (DFU) is the main cause of disability in diabetic patients. However, the molecular changes underlying the occurrence and progression of DFU remain unclear. We conducted this study to examine gene alterations in different DFU patients. Methods: GSE143735 and GSE134431 transcriptome data sets were acquired from the Gene Expression Omnibus database, and differential expression analyses of the genes in these data sets were performed. A functional enrichment analysis of the differentially expressed genes (DEGs) was performed using clusterProfiler package in R. To examine the correlations between DEGs and significant immune-related genes, we identified the intersecting ulcer-related DEGs, healing-related DEGs, and immune-related DEGs. Finally, we further investigate the relationship between the selected genes with immune cell regulation via a single-sample gene set enrichment analysis, and the infiltration of 28 immune cells in common diabetes samples, unhealed DFU samples, and healed samples DFU were compared. Results: We found 238 upregulated genes and 207 downregulated genes in the diabetic foot (DF) patients with ulcers compared to the DF patients without ulcers, and 74 upregulated genes and 28 downregulated genes in the healed samples compared to the unhealed samples. To examine the main biological functions, we conducted a functional enrichment analysis. The results showed that the biological functions of functional enrichment analysis included neutrophil degranulation, leukocyte chemotaxis, myeloid leukocyte migration, phagosome, cytokine-cytokine receptor interaction, and the chemokine signaling pathway. Interleukin (IL)-1B was more highly expressed in patients with ulcers and healed DFU patients than those without ulcers and unhealed DFU patients. Finally, the immune cell abundance difference results showed that activated cluster of differentiation (CD)8 T cells, central memory CD8 T cells, T follicular helper cells, myeloid-derived suppressor cells, natural killer T cells and monocytes were more highly infiltrated in normal diabetes patients and healed DFU patients than unhealed DFU patients. However, no difference was found between DF patients with and without ulcers. Conclusions: IL-1B is an inflammation gene that can be used to assess and regulate DFU progression.

Proximity hybridization induced rolling circle amplification for label-free SERS detection of the depression marker human apolipoprotein A4.

A new label-free method was developed for SERS detection of human apolipoprotein A4. Rolling circle amplification (RCA) was used, which could induce the production of AuNPs (poly adenine and adsorption gold nanoparticles). When there were two DNA labeled antibodies and target protein, MB1 (molecular beacon 1) was unfolded and the substrate was modified in the homogeneous solution, and the proximate complex was formed. The unfolded molecular beacon worked as a primer in the hybridization with the RCA template to start RCA, which could produce many long sequences of DNA containing amounts of adenines. The AuNPs were bound with the long-repeated adenine in the RCA product, causing accumulation of AuNPs on the surface of the electrode. It was indicated that the spectral characteristics of adenine at 736 cm-1 strongly dominated the SERS spectrum of DNA. Adenine worked as an internal marker for detecting human apolipoprotein A4 by using label-free SERS method. When the conditions were optimal, the detection of human apolipoprotein A4 was carried out from 10 pg mL-1 to 1000 ng mL-1, and the detection limit was low (4.1 pg mL-1). Meanwhile, the specificity was also excellent because the antibody could specifically bind with the corresponding antigen. In addition, since adenine was dominant in SERS spectra and the affinity between AuNPs and poly adenine was high, the detection procedure could be performed without any sophisticated modification. This method might provide a promising strategy for diagnosis in clinical practice.

Exosomes Derived from Epidermal Stem Cells Improve Diabetic Wound Healing.

Diabetic foot ulceration is a major diabetic complication with unmet needs. We investigated the efficacy of epidermal stem cells and epidermal stem cells-derived exosomes (ESCs-Exo) in improving impaired diabetic wound healing and their mechanisms of action. In vitro experiments showed that ESCs-Exo enhanced the proliferation and migration of diabetic fibroblasts and macrophages and promoted alternative or M2 macrophage polarization. In wounds of db/db mice, treatment with both epidermal stem cells and ESCs-Exo, when compared with fibroblast exosomes and PBS control, accelerated wound healing by decreasing inflammation, augmenting wound cell proliferation, stimulating angiogenesis, and inducing M2 macrophage polarization. Multiplex protein quantification of wound lysates revealed TGFß signaling influenced by ESCs-Exo. High-throughput sequencing of small RNAs contained in the ESCs-Exo showed higher proportions of microRNAs than those contained in fibroblast exosomes. In silico functional analysis showed that the ESCs-Exo microRNAs‒target genes were primarily involved in homeostatic processes and cell differentiation and highlighted regulatory control of phosphatidylinositol-3 kinase/protein kinase B and TGFß signaling pathways. This was also validated in vitro. Collectively, our results indicate that epidermal stem cells and ESCs-Exo are equally effective in promoting impaired diabetic wound healing and that ESCs-Exo treatment may be a promising and technically advantageous alternative to stem cell therapies.

Circular RNA circVEGFC accelerates high glucose-induced vascular endothelial cells apoptosis through miR-338-3p/HIF-1α/VEGFA axis.

More and more findings illustrate the critical roles of circular RNA (circRNA) in diabetes mellitus (DM) and its complications. A major pathological characteristic for DM is the apoptosis of endothelial cells (ECs) induced by high glucose (HG), however, the function of circRNA in the ECs' phenotypes is still elusive. Here, this study identified an up-regulated circRNA (circVEGFC) in the HG-induced human umbilical vein endothelial cells (HUVECs). Functionally, knockdown of circVEGFC alleviated the apoptosis and recovered the proliferation in HUVECs induced by HG administration. Mechanistically, circVEGFC functioned as the sponge of miR-338-3p, and miR-338-3p was found to target the 3'-Untranslated Regions (3'-UTR) of hypoxia inducible factor 1 alpha (HIF-1α). HIF-1α, a critical transcription factor in DM, could activate the transcription of vascular endothelial growth factor A (VEGFA) and promote its protein product. In conclusion, these findings reveal the promotion of circVEGFC/miR-338-3p/HIF-1α/VEGFA axis in the HG-induced ECs' apoptosis, providing a potential treatment strategy for ECs' damage in DM.

Circulating Expression Level of LncRNA Malat1 in Diabetic Kidney Disease Patients and Its Clinical Significance.

BACKGROUND: Long noncoding RNA MALAT1 is closely related to diabetes and kidney diseases and is expected to be a new target for the diagnosis and treatment of diabetic nephropathy. OBJECTIVE: This study aimed to explore the circulating expression level and significance of lncRNA Malat1 in patients with type 2 diabetes mellitus (T2DM) and diabetic kidney disease (DKD). METHODS: Quantitative real-time PCR (qPCR) was conducted to assess the expression of lncRNA Malat1 in 20 T2DM patients, 27 DKD patients, and 14 healthy controls, and then, the clinical significance was analyzed. RESULTS: LncRNA MALAT1 expression in peripheral blood mononuclear cells (PBMC) was significantly upregulated in T2DM and DKD groups when compared to control. Pearson's correlation analysis showed correlation of lncRNA MALAT1 levels with ACR, urine ß2-microglobulin (ß2-MG), urine α1-microglobulin (α1-MG), creatinine (Cr), and glycosylated hemoglobin (HbA1c), while negative with superoxide dismutase (SOD) (r = -0.388, P < 0.05). Binary regression analysis showed that ACR, creatinine, α1-MG, and LncRNA Malat1 were the risk factors for diabetic nephropathy with OR value of 1.166, 1.031, 1.031, and 2.019 (P < 0.05). The area under ROC curve (AUC) of DKD identified by the above indicators was 0.914, 0.643, 0.807, and 0.797, respectively. The AUC of Joint prediction probability of DKD recognition was 0.914, and the sensitivity and specificity of DKD diagnosis were 1.0 and 0.806, respectively. (Take ≥0.251 as the diagnostic cutoff point). CONCLUSION: LncRNA Malat1 is highly expressed in DKD patients, and the combined detection of ACR, creatinine, α1-MG, and LncRNA Malat1 with diabetes mellitus may be the best way to diagnose diabetic nephropathy.

Effect of Aluminum Exposure on Glucose Metabolism and Its Mechanism in Rats.

The effects of aluminum (Al) exposure on glucose metabolism and its mechanism were investigated. A total of 30 healthy Wistar male rats were randomly divided into two groups: control (GC) and experimental (GE). The GC group received intraperitoneal normal saline. The GE was established by intraperitoneal injected AlCl3 solution at 10 mg/kg for 30 days. Fasting blood glucose (FBG) and serum levels of insulin (FINS) were measured. The insulin resistance index (HOMA-IR) and pancreatic ß cell function index (HOMA-ß) were calculated and analyzed with homeostasis model assessment (HOMA). Pancreatic tissue was taken for pathological examination. Glucose transporter 4 (GLUT4) expression in skeletal muscle was detected by quantitative PCR and Western blot. Levels of FBG and HOMA-IR in GE were higher than those in GC at day 10 and 20 (P < 0.05). FINS in GE were higher than those in GC at day 10 and 20, and lower than those in GC at day 30 (P < 0.05). HOMA-ß in GE was lower than that of GC at every time point (P < 0.05). Pathology showed that pancreatic damage changed more profoundly with prolongation of time in GE. Expression levels of GLUT4 mRNA and protein in rat skeletal muscle in GE were significantly lower than those in GC (P < 0.05). The results suggested that Al exposure affected glucose metabolism through pancreatic damage and reduction of GLUT4 expression.