WDR74 facilitates TGF-β/Smad pathway activation to promote M2 macrophage polarization and diabetic foot ulcer wound healing in mice

Mechanistic insights into Hippo-YAP pathway activation for enhanced DFU healing

With the increasing prevalence of diabetes, diabetic foot ulcers (DFUs) have become a global health challenge, significantly impacting patients' quality of life and placing a substantial burden on healthcare systems. Among various immune cell subsets, M2-polarized macrophages play a pivotal role in tissue repair and inflammation resolution. This study uses single-cell RNA sequencing (scRNA-seq) and bulk RNA sequencing to comprehensively investigate the role of the TFAP2A-LIFR-Hippo-YAP signaling axis in regulating macrophage M2 polarization and its critical function in DFU wound healing. Through scRNA-seq analysis, we identified nine major immune cell subsets in DFU samples, with macrophages emerging as key regulatory cells. In vitro experiments further confirmed that TFAP2A promotes macrophage M2 polarization (evidenced by increased expression of the M2 marker ARG1) and ameliorates endothelial dysfunction by enhancing tube formation, improving migration capacity, and upregulating relevant proteins such as VCAM-1. Moreover, TFAP2A serves as a central regulatory gene for macrophage function in DFU by upregulating LIFR expression and activating the Hippo-YAP signaling pathway, thereby inducing M2 polarization and mitigating endothelial dysfunction. Mouse model experiments further demonstrated that the TFAP2A-LIFR-Hippo-YAP signaling axis accelerates DFU wound healing through the induction of macrophage M2 polarization. This study unveils a novel immunoregulatory role of TFAP2A in DFU and provides a promising therapeutic target for the treatment of chronic diabetic wounds.NEW & NOTEWORTHY This study provides unprecedented insights into diabetic foot ulcer healing by demonstrating the novel immunoregulatory role of the TFAP2A-LIFR-Hippo-YAP signaling axis. Leveraging single-cell and bulk transcriptomics, we identify TFAP2A as a crucial regulator of macrophage M2 polarization, essential for wound healing and angiogenesis. These findings offer valuable mechanistic understanding and present TFAP2A as a promising therapeutic target for improving outcomes in chronic diabetic wounds.

Progress of microneedle targeted modulation technology in the reconstruction of immune microenvironment in diabetic wounds

Wound healing in diabetic patients is mainly hindered by a combination of long-term glycosylation, persistent inflammatory response, and immunosuppressive state. The interaction of these factors not only results in considerable prolongation of the wound healing process but also elevates the likelihood of recurrent ulcer development, profoundly affecting patients' quality of life. Traditional treatments, including surgical debridement, anti-infection, dressing application, vascular intervention, and glycaemic control, can only relieve some symptoms. However, they are often ineffective in addressing the underlying cause of impaired wound healing. It is of concern that the importance of the immune microenvironment in diabetic wound healing has not yet been fully appreciated and investigated, and the homeostasis of the immune microenvironment is crucial for promoting cell proliferation, angiogenesis, and tissue repair. However, this microenvironment is often dysregulated in the diabetic state. This paper reviews the key factors leading to dysregulation of the immune microenvironment, including immune cell dysfunction, abnormal cytokine expression, and disruption of key signalling pathways, and introduces an innovative silicone-based microneedle drug delivery method, which takes advantage of microneedle's precise targeting and highly efficient drug loading capacity to deliver drugs with immunomodulatory functions directly to the wound in a sustained manner, activate the corresponding signalling pathways, promote the polarization of M1 macrophages into the M2 phenotype, and stimulate neovascularization, providing a low inflammatory and pro-angiogenic immune microenvironment for diabetic wound healing, which provides a new therapeutic idea and means for diabetic wound healing.

Platelet-rich plasma-derived exosomes accelerate the healing of diabetic foot ulcers by promoting macrophage polarization toward the M2 phenotype

Diabetic foot ulcers (DFUs) impose a significant clinical and socioeconomic burden on patients and healthcare systems. Although platelet-rich plasma (PRP) and platelet-rich plasma-derived exosomes (PRP-Exos) have emerged as promising therapeutic agents in tissue regeneration, the mechanisms underlying the immunomodulatory effects of PRP and PRP-Exos-particularly their role in macrophage polarization-remain poorly understood. In this study, we isolated and characterized PRP-Exos and systematically evaluated their therapeutic potential in diabetic wound healing via comprehensive in vivo and in vitro experiments. Our results revealed that both PRP-gel and PRP-Exos significantly enhanced diabetic wound healing by promoting macrophage polarization toward the anti-inflammatory M2 phenotype. These findings suggest that PRP-Exos represent a novel and effective therapeutic strategy for DFUs, providing a robust rationale for future clinical translation.

Mesenchymal Stem Cell-Derived Exosomes Hold Promise in the Treatment of Diabetic Foot Ulcers

Diabetic foot ulcers (DFU) represent one of the most common side effects of diabetes, significantly impacting patients' quality of life and imposing considerable financial burdens on families and society at large. Despite advancements in therapies targeting lower limb revascularization and various medications and dressings, outcomes for patients with severe lesions remain limited. A recent breakthrough in DFU treatment stems from the development of mesenchymal stem cells (MSCs). MSCs have shown promising results in treating various diseases and skin wounds due to their ability for multidirectional differentiation and immunomodulation. Recent studies highlight that MSCs primarily repair tissue through their paracrine activities, with exosomes playing a crucial role as the main biologically active components. These exosomes transport proteins, mRNA, DNA, and other substances, facilitating DFU treatment through immunomodulation, antioxidant effects, angiogenesis promotion, endothelial cell migration and proliferation, and collagen remodeling. Mesenchymal stem cell-derived exosomes (MSC-Exo) not only deliver comparable therapeutic effects to MSCs but also mitigate adverse reactions like immune rejection associated with MSCs transplantation. This article provides an overview of DFU pathophysiology and explores the mechanisms and research progress of MSC-Exo in DFU therapy.

LA-peptide Hydrogel-Regulation of macrophage and fibroblast fates and their crosstalk via attenuating TGF-β to promote scarless wound healing

The homeostasis of the wound microenvironment is fundamental for scarless wound healing, while the excessive accumulation of transforming growth factor-beta (TGF-β) in the wound microenvironment always leads to hypertrophic scars (HS) formation by regulating cell fates and crosstalk among various types of cells, such as macrophages and fibroblasts. This study reports that an injectable, self-assembling LA-peptide hydrogel has the potential to facilitate scarless cutaneous wound healing through dynamically adsorbing TGF-β within the wound environment. We found that the released LA peptides led to the suppression of both the PI3K/Akt and TGF-β/Smad2/3 pathways in macrophages and fibroblasts. As expected, the application of LA-peptide hydrogel alleviated the M2 type polarization of macrophages and inhibited fibroblasts activation by adsorbing TGF-β both in vitro and in vivo. Furthermore, designated concentrations of the LA-peptide hydrogel achieved controlled release of LA peptides, enabling dynamic regulation of TGF-β for maintaining microenvironment homeostasis during different phases of wound healing. This contributed to the inhibition of HS formation without delaying wound healing in both a mouse full-thickness skin wound model and a rabbit ear scar model. Overall, the LA-peptide hydrogel provides promising avenues for promoting scarless healing of wounds, exemplifying precision medicine-guided targeting of specific pathogenic molecules, such as TGF-β, and highlighting the significance of dynamic regulation of TGF-β homeostasis in wound microenvironment.

Microenvironment of diabetic foot ulcers: Implications for healing and therapeutic strategies

Diabetic foot ulcers (DFUs) are a common yet serious complication in individuals with diabetes, often presenting as chronic, nonhealing wounds that significantly impair quality of life. The healing process of DFUs is largely influenced by the local microenvironment, which encompasses factors such as hypoxia, inflammation, and the involvement of various cell types. Poor blood circulation in the affected area results in hypoxia, compromising cellular function and restricting nutrient supply, thereby delaying wound healing. In addition, chronic inflammation disrupts immune system balance, with excessive pro-inflammatory cytokines not only failing to facilitate tissue repair but also exacerbating tissue damage. Moreover, key cell types, including fibroblasts, keratinocytes, and macrophages, play crucial roles at different stages of the healing process, contributing to collagen production and skin regeneration. A comprehensive understanding of the complex dynamics within the DFU microenvironment is essential for developing more precise therapeutic approaches, such as advanced drug delivery systems and bioactive materials, aimed at promoting wound healing and reducing the risk of recurrence.

Exosomes derived from fibroblasts in DFUs delay wound healing by delivering miR-93-5p to target macrophage ATG16L1

Diabetes is an extremely costly disease, one-third of which are attributed to the management of diabetic foot disease including chronic, non-healing, diabetic foot ulcers (DFUs). Therefore, much effort is needed to understand the pathogenesis of DFUs and novel therapeutics. We utilized exosome staining to confirm the interaction between fibroblast-derived exosomes and macrophages. Subsequently, we employed public data and qPCR to screen for upregulated miRNAs in fibroblast-derived exosomes in DFUs. The relationship between was validate miR-93-5 and ATG16L1 through data prediction and dual-luciferase reporter assays. A variety of molecular biology experiments were used for subsequent pathway validation. Additionally, we established Atg16l1MKI and Nlrp3MKO mice for further validation. We identified that miR-93-5p derived from fibroblasts played an important role in M1 macrophages polarization. Predicted by database, we found that miR-93-5p can bind to ATG16L1 mRNA, thereby influencing macrophage autophagy mediated by ATG16L1 in the clearance of ROS, thus activating the NLRP3 signaling pathway. In vivo, miR-93-5p antagomir treatment accelerated diabetic wound healing and induced M2 macrophage polarization. Fibroblasts and macrophages show cell crosstalk during the development of DFUs by miR-93-5p, and that antagomir treatment may be a promising and technically advantageous alternative to DFUs therapies.

Angiogenesis during diabetic wound repair: from mechanism to therapy opportunity

Diabetes mellitus, a pervasive chronic metabolic disorder, is often associated with complications such as impaired wound healing. Various factors, most notably vascular deficiency, govern the wound repair process in diabetic patients, significantly impeding diabetic wound healing; therefore, angiogenesis and its role in diabetic wound repair have emerged as important areas of research. This review aims to delve into the mechanisms of angiogenesis, the effects of diabetes on angiogenesis, and the association between angiogenesis and diabetic wound repair. This will ultimately offer valuable guidance regarding the ideal timing of diabetic wound treatment in a clinical setting.

Tp53 determines the spatial dynamics of M1/M2 tumor-associated macrophages and M1-driven tumoricidal effects

The spatial role of M1 and M2 tumor-associated macrophages (M1/M2 TAMs) in precision medicine remains unclear. EGFR and TP53 are among the most frequently mutated genes in lung adenocarcinoma. We characterized the mutation status and density of M1/M2 TAMs within tumor islets and stroma in 117 lung adenocarcinomas using next-generation sequencing and immunohistochemistry, respectively. Stromal M1 TAMs were positively correlated with disease progression and smoking history. In contrast, islet M1/M2 TAMs were predominantly found in tumors with wild-type TP53 (wtp53) but not associated with EGFR status. The presence of wtp53 was associated with the spatial distribution of M1/M2 TAMs in tumor islets and stroma. Additionally, dominance of islet M1 TAMs and M1-signature were significantly associated with improved survival in patients with wtp53 lung adenocarcinoma, unlike in those with mutant TP53. Conditioned medium from M1 macrophages (M1 CM) induced apoptosis in wtp53 cells through increased p53 accumulation. We found that interferons in M1 CM activate JAK1/TYK2 via IFNARs, leading to enhanced STAT1 expression and Y701 phosphorylation. This activation facilitates p53-STAT1 interactions, reduces the interaction between p53 and MDM2, and subsequently decreases p53 ubiquitination. M1 CM inhibited tumorigenesis, and silencing p53 reduced the anti-tumor efficacy of polyinosinic:polycytidylic acid (poly I:C) in vivo. Furthermore, higher M1-signature was significantly associated with better responses and survival following anti-PD1 treatment in wtp53 melanomas. IFNs/STAT1/p53 signaling was critical for the anti-tumor activity of M1 macrophages. These findings suggest that p53 modulates the spatial balance of M1/M2 TAMs, and the tumoricidal effects of M1 TAMs depend on p53 status. Thus, p53 companion diagnostics could facilitate the development of M1-oriented therapies, which may be particularly beneficial for wtp53 patients when combined with immunotherapy.

Comprehensive analysis of scRNA-seq and bulk RNA-seq reveals the non-cardiomyocytes heterogeneity and novel cell populations in dilated cardiomyopathy

BACKGROUND

Dilated cardiomyopathy (DCM) is one of the most common causes of heart failure. Infiltration and alterations in non-cardiomyocytes of the human heart involve crucially in the occurrence of DCM and associated immunotherapeutic approaches.

METHODS

We constructed a single-cell transcriptional atlas of DCM and normal patients. Then, the xCell algorithm, EPIC algorithm, MCP counter algorithm, and CIBERSORT method were applied to identify DCM-related cell types with a high degree of precision and specificity using RNA-seq datasets. We further analyzed the heterogeneity among cell types, performed trajectory analysis, examined transcription factor regulatory networks, investigated metabolic heterogeneity, and conducted intercellular communication analysis. Finally, we used bulk RNA-seq data to confirm the roles of M2-like2 subpopulations and GAS6 in DCM.

RESULTS

We integrated and analyzed Single-cell sequencing (scRNA-seq) data from 7 DCM samples and 3 normal heart tissue samples, totaling 70,958 single-cell data points. Based on gene-specific expression and prior marker genes, we identified 9 distinct subtypes, including fibroblasts, endothelial cells, myeloid cells, pericytes, T/NK cells, smooth muscle cells, neuronal cells, B cells, and cardiomyocytes. Using machine learning methods to quantify bulk RNA-seq data, we found significant differences in fibroblasts, T cells, and macrophages between DCM and normal samples. Further analysis revealed high heterogeneity in tissue preference, gene expression, functional enrichment, immunodynamics, transcriptional regulatory factors, metabolic changes, and communication patterns in fibroblasts and myeloid cells. Among fibroblast subpopulations, proliferative F3 cells were implicated in the fibroblast transition process in DCM, while myofibroblast F6 cells promoted the fibroblast transition to a late cell state in DCM. Additionally, two subpopulations of M2 macrophages, M2-like1 and M2-like2, were identified with distinct features. The M2-like2 cell subpopulation, which was enriched in glycolysis and fatty acid metabolism, involved in inflammation inhibition and fibrosis promotion. Cell‒cell communication analysis indicated the GAS6-MERTK axis might exhibit interaction between M2 macrophage and M2-like1 macrophage. Furthermore, deconvolution analysis for bulk RNA-seq data revealed a significant increase in M2-like2 subpopulations in DCM, suggesting a more important role for this cell population in DCM.

CONCLUSIONS

We revealed the heterogeneity of non-cardiomyocytes in DCM and identified subpopulations of myofibroblast and macrophages engaged in DCM, which suggested a potential significance of non-cardiomyocytes in treatment of DCM.

TWEAK increases angiogenesis to promote diabetic skin wound healing by regulating Fn14/EGFR signaling

OBJECTIVE

Tumor necrosis factor-like weak inducer of apoptosis (TWEAK), a member of tumor necrosis factor superfamily, can bind to fibroblast growth factor-inducible 14 (Fn14) receptor and stimulate angiogenesis. The interaction between epidermal growth factor receptor (EGFR) and endothelial growth factor (EGF) leads to EGFR signal transduction and promotes angiogenesis. The objective of this study was to explore whether TWEAK participated in the diabetic skin wound healing by regulating Fn14/EGFR signaling.

METHODS

Human umbilical vein endothelial cells (HUVECs) were treated with 35 mmol/L d-glucose and classified into the Control Group, High Glucose (HG) Group and HG + TWEAK Group. Then, the TWEAK expression and the proliferation, migration and tubule formation of HUVECs were detected, respectively. In vivo experiment, the diabetic model was established by injecting streptozotocin (STZ, 50 mg/kg) into male BALB/c mice. On the back of successfully modeled diabetic mice, a full-thickness skin wound of 6 mm diameter was formed. Then, the mice were randomly assigned into three groups: Blank Group, Phosphate Buffer Saline (PBS) Group, and TWEAK Group. Subsequently, expression levels of TWEAK, Fn14, EGFR and vascular endothelial growth factor (VEGF)-A were measured, and the CD31 expression in the wounded skin tissue of mice was checked by immunohistochemistry staining.

RESULTS

The expression level of TWEAK in HUVECs of HG Group decreased significantly, as well as the viability, migration, and tubule formation of cells. After over-expression of TWEAK, the cell viability, migration, and tubule formation abilities of HUVECs recovered remarkably. In vivo, the wound healing rate of diabetic mice was raised, the neovascularization was increased, and the CD31 expression in the wounded tissue was obviously upregulated after injection with recombinant TWEAK antibody.

CONCLUSION

TWEAK stimulates angiogenesis and accelerates the wound healing of diabetic skin by regulating Fn14/EGFR signaling.

Role of miRNAs in macrophage-mediated kidney injury

Macrophages, crucial components of the human immune system, can be polarized into M1/M2 phenotypes, each with distinct functions and roles. Macrophage polarization has been reported to be significantly involved in the inflammation and fibrosis observed in kidney injury. MicroRNA (miRNA), a type of short RNA lacking protein-coding function, can inhibit specific mRNA by partially binding to its target mRNA. The intricate association between miRNAs and macrophages has been attracting increasing interest in recent years. This review discusses the role of miRNAs in regulating macrophage-mediated kidney injury. It shows how miRNAs can influence macrophage polarization, thereby altering the biological function of macrophages in the kidney. Furthermore, this review highlights the significance of miRNAs derived from exosomes and extracellular vesicles as a crucial mediator in the crosstalk between macrophages and kidney cells. The potential of miRNAs as treatment applications and biomarkers for macrophage-mediated kidney injury is also discussed.

Neu1 deficiency and fibrotic lymph node microenvironment lead to imbalance in M1/M2 macrophage polarization

Macrophages play a pivotal role in tissue homeostasis, pathogen defense, and inflammation resolution. M1 and M2 macrophage phenotypes represent two faces in a spectrum of responses to microenvironmental changes, crucial in both physiological and pathological conditions. Neuraminidase 1 (Neu1), a lysosomal and cell surface sialidase responsible for removing terminal sialic acid residues from glycoconjugates, modulates several macrophage functions, including phagocytosis and Toll-like receptor (TLR) signaling. Current evidence suggests that Neu1 expression influences M1/M2 macrophage phenotype alterations in the context of cardiovascular diseases, indicating a potential role for Neu1 in macrophage polarization. For this reason, we investigated the impact of Neu1 deficiency on macrophage polarization in vitro and in vivo. Using bone marrow-derived macrophages (BMDMs) and peritoneal macrophages from Neu1 knockout (Neu1-/- ) mice and wild-type (WT) littermate controls, we demonstrated that Neu1-deficient macrophages exhibit an aberrant M2-like phenotype, characterized by elevated macrophage mannose receptor 1 (MMR/CD206) expression and reduced responsiveness to M1 stimuli. This M2-like phenotype was also observed in vivo in peritoneal and splenic macrophages. However, lymph node (LN) macrophages from Neu1-/- mice exhibited phenotypic alterations with reduced CD206 expression. Further analysis revealed that peripheral LNs from Neu1-/- mice were highly fibrotic, with overexpression of transforming growth factor-beta 1 (TGF-β1) and hyperactivated TGF-β signaling in LN macrophages. Consistently, TGF-β1 was found to alter M1/M2 macrophage polarization in vitro. Our findings showed that Neu1 deficiency prompts macrophages towards an M2 phenotype and that microenvironmental changes, particularly increased TGF-β1 in fibrotic tissues such as peripheral LNs in Neu1-/- mice, further influence M1/M2 macrophage polarization, highlighting its sensitivity to the local microenvironment. Therapeutic interventions targeting Neu1 or TGF-β signaling pathways may offer the potential to regulate macrophage behavior across different diseases.

Neural and immune roles in osteoarthritis pain: Mechanisms and intervention strategies

Pain is the leading symptom for most individuals with osteoarthritis (OA), a complex condition marked by joint discomfort. Recently, the dynamic interplay between the nervous and immune systems has become a focal point for understanding pain regulation. Despite this, there is still a substantial gap in our comprehensive understanding of the neuroimmune interactions and their effects on pain in OA. This review examines the bidirectional influences between immune cells and nerves in OA progression. It explores current approaches that target neuroimmune pathways, including promoting M2 macrophage polarization and specific neuronal receptor targeting, for effective pain reduction.

Translational potential statement

This review provides a comprehensive overview of the mechanisms underlying the interplay between the immune system and nervous system during the progression of OA, as well as their contributions to pain. Additionally, it compiles existing intervention strategies targeting neuroimmunity for the treatment of OA pain. This information offers valuable insights for researchers seeking to address the challenge of OA pain.

Structure, unique biological properties, and mechanisms of action of transforming growth factor β

Transforming growth factor β (TGF-β) is a ubiquitous molecule that is extremely conserved structurally and plays a systemic role in human organism. TGF-β is a homodimeric molecule consisting of two subunits joined through a disulphide bond. In mammals, three genes code for TGF-β1, TGF-β2, and TGF-β3 isoforms of this cytokine with a dominating expression of TGF-β1. Virtually, all normal cells contain TGF-β and its specific receptors. Considering the exceptional role of fine balance played by the TGF-β in anumber of physiological and pathological processes in human body, this cytokine may be proposed for use in medicine as an immunosuppressant in transplantology, wound healing and bone repair. TGFb itself is an important target in oncology. Strategies for blocking members of TGF-β signaling pathway as therapeutic targets have been considered. In this review, signalling mechanisms of TGF-β1 action are addressed, and their role in physiology and pathology with main focus on carcinogenesis are described.

Effects of HOX family regulator-mediated modification patterns and immunity characteristics on tumor-associated cell type in endometrial cancer

Endometrial cancer (UCEC) is one of three major malignant tumors in women. The HOX gene regulates tumor development. However, the potential roles of HOX in the expression mechanism of multiple cell types and in the development and progression of tumor microenvironment (TME) cell infiltration in UCEC remain unknown. In this study, we utilized both the The Cancer Genome Atlas (TCGA) database and International Cancer Genome Consortium (ICGC) database to analyze transcriptome data of 529 patients with UCEC based on 39 HOX genes, combing clinical information, we discovered HOX gene were a pivotal factor in the development and progression of UCEC and in the formation of TME diversity and complexity. Here, a new scoring system was developed to quantify individual HOX patterns in UCEC. Our study found that patients in the low HOX score group had abundant anti-tumor immune cell infiltration, good tumor differentiation, and better prognoses. In contrast, a high HOX score was associated with blockade of immune checkpoints, which enhances the response to immunotherapy. The Real-Time quantitative PCR (RT-qPCR) and Immunohistochemistry (IHC) exhibited a higher expression of the HOX gene in the tumor patients. We revealed that the significant upregulation of the HOX gene in the epithelial cells can activate signaling pathway associated with tumour invasion and metastasis through single-cell RNA sequencing (scRNA-seq), such as nucleotide metabolic proce and so on. Finally, a risk prognostic model established by the positive relationship between HOX scores and cancer-associated fibroblasts (CAFs) can predict the prognosis of individual patients by scRNA-seq and transcriptome data sets. In sum, HOX gene may serve as a potential biomarker for the diagnosis and prediction of UCEC and to develop more effective therapeutic strategies.

PFDA promotes cancer metastasis through macrophage M2 polarization mediated by Wnt/β-catenin signaling

Perfluoroundecanoic acid (PFDA) is extensively utilized in the textile and food processing industries and may have a tumor-promoting effect by modulating the tumor microenvironment. Macrophages play crucial roles in tumor microenvironment as key regulators of tumor immunity. However, further investigation is needed to elucidate how PFDA interacts with macrophages and contributes to tumor progression. In this study, we treated the macrophage cell line RAW264.7 with various concentrations of PFDA and found that RAW264.7 transitioned into an M2 tumor-promoting phenotype. Through bioinformatic analysis and subsequent verification of molecular assays, we uncovered that PFDA could activate β-catenin and enhance its nuclear translocation. Additionally, it was also observed that inhibiting β-catenin nuclear translocation partly attenuated RAW264.7 M2 polarization induced by PFDA. The conditioned medium derived from PFDA-pretreated RAW264.7 cells significantly promoted the migration and invasion abilities of human ovarian cancer cells. Furthermore, in vivo studies corroborated that PFDA-pretreated RAW264.7 could promote tumor metastasis, which could be mitigated by pretreatment with the β-catenin inhibitor ICG001. In conclusion, our study demonstrated that PFDA could promote cancer metastasis through regulating macrophage M2 polarization in a Wnt/β-catenin-dependent manner.

Healing the diabetic wound: Unlocking the secrets of genes and pathways

Diabetic wounds (DWs) are open sores that can occur anywhere on a diabetic patient's body. They are often complicated by infections, hypoxia, oxidative stress, hyperglycemia, and reduced growth factors and nucleic acids. The healing process involves four phases: homeostasis, inflammation, proliferation, and remodeling, regulated by various cellular and molecular events. Numerous genes and signaling pathways such as VEGF, TGF-β, NF-κB, PPAR-γ, MMPs, IGF, FGF, PDGF, EGF, NOX, TLR, JAK-STAT, PI3K-Akt, MAPK, ERK, JNK, p38, Wnt/β-catenin, Hedgehog, Notch, Hippo, FAK, Integrin, and Src pathways are involved in these events. These pathways and genes are often dysregulated in DWs leading to impaired healing. The present review sheds light on the pathogenesis, healing process, signaling pathways, and genes involved in DW. Further, various therapeutic strategies that target these pathways and genes via nanotechnology are also discussed. Additionally, clinical trials on DW related to gene therapy are also covered in the present review.

Marrow mesenchymal stem cell mediates diabetic nephropathy progression via modulation of Smad2/3/WTAP/m6A/ENO1 axis

Diabetic nephropathy (DN) is one of the common microvascular complications in diabetic patients. Marrow mesenchymal stem cells (MSCs) have attracted attention in DN therapy but the underlying mechanism remains unclear. Here, we show that MSC administration alleviates high glucose (HG)-induced human kidney tubular epithelial cell (HK-2 cell) injury and ameliorates renal injury in DN mice. We identify that Smad2/3 is responsible for MSCs-regulated DN progression. The activity of Smad2/3 was predominantly upregulated in HG-induced HK-2 cell and DN mice and suppressed with MSC administration. Activation of Smad2/3 via transforming growth factor-β1 (TGF-β1) administration abrogates the protective effect of MSCs on HG-induced HK-2 cell injury and renal injury of DN mice. Smad2/3 has been reported to interact with methyltransferase of N6-methyladenosine (m6A) complex and we found a methyltransferase, Wilms' tumor 1-associating protein (WTAP), is involved in MSCs-Smad2/3-regulated DN development. Moreover, WTAP overexpression abrogates the improvement of MSCs on HG-induced HK-2 cell injury and renal injury of DN mice. Subsequently, α-enolase (ENO1) is the downstream target of WTAP-mediated m6A modification and contributes to the MSCs-mediated regulation. Collectively, these findings reveal a molecular mechanism in DN progression and indicate that Smad2/3/WTAP/ENO1 may present a target for MSCs-mediated DN therapy.

Dang-Gui-Si-Ni decoction facilitates wound healing in diabetic foot ulcers by regulating expression of AGEs/RAGE/TGF-β/Smad2/3

Diabetic foot ulcer (DFU) is a predominant complication of diabetes mellitus with poor prognosis accompanied by high amputation and mortality rates. Dang-Gui-Si-Ni decoction (DSD), as a classic formula with a long history in China, has been found to improve DFU symptoms. However, mechanism of DSD for DFU therapy remains unclear with no systematic elaboration. In vivo, following establishment of DFU rat model, DSD intervention with low, medium and high doses was done, with Metformin (DM) as a positive control group. With wound healing detection, pathological changes by HE staining, inflammatory factor expression by ELISA and qRT-PCR, oxidative stress levels by ELISA, and AGEs/RAGE/TGF-β/Smad2/3 expression by Western blot were performed. In vitro, intervention with LY2109761 (TGF-β pathway inhibitor) based on DSD treatment in human dermal fibroblast-adult (HDF-a) cells was made. Cell viability by CCK8, migration ability by cell scratch, apoptosis by flow cytometry, and AGEs/RAGE/TGF-β/Smad2/3 expression by Western blot were measured. DFU rats exhibited elevated AGEs/RAGE expression, whereas decreased TGF-β1 and p-Smad3/Smad3 protein expression, accompanied by higher IL-1β, IL-6, TNF-α levels, and oxidative stress. DSD intervention reversed above effects. Glucose induction caused lower cell viability, migration, TGF-β1 and p-Smad3/Smad3 protein expression, with increased apoptosis and AGEs/RAGE expression in HDF-a cells. These effects were reversed after DSD intervention, and further LY2109761 intervention inhibited DSD effects in cells. DSD intervention may facilitate wound healing in DFU by regulating expression of AGEs/RAGE/TGF-β/Smad2/3, providing scientific experimental evidence for DSD clinical application for DFU therapy.

Strategies to reprogram anti-inflammatory macrophages towards pro-inflammatory macrophages to support cancer immunotherapies

Tumor-associated myeloid cells, including macrophages and myeloid-derived suppressor cells, can be highly prevalent in solid tumors and play a significant role in the development of the tumor. Therefore, myeloid cells are being considered potential targets for cancer immunotherapies. In this review, we focused on strategies aimed at targeting tumor-associated macrophages (TAMs). Most strategies were studied preclinically but we also included a limited number of clinical studies based on these strategies. We describe possible underlying mechanisms and discuss future challenges and prospects.

A xonotlite nanofiber bioactive 3D-printed hydrogel scaffold based on osteo-/angiogenesis and osteoimmune microenvironment remodeling accelerates vascularized bone regeneration

BACKGROUND

Coordination between osteo-/angiogenesis and the osteoimmune microenvironment is essential for effective bone repair with biomaterials. As a highly personalized and precise biomaterial suitable for repairing complex bone defects in clinical practice, it is essential to endow 3D-printed scaffold the above key capabilities.

RESULTS

Herein, by introducing xonotlite nanofiber (Ca6(Si6O17) (OH)2, CS) into the 3D-printed silk fibroin/gelatin basal scaffold, a novel bone repair system named SGC was fabricated. It was noted that the incorporation of CS could greatly enhance the chemical and mechanical properties of the scaffold to match the needs of bone regeneration. Besides, benefiting from the addition of CS, SGC scaffolds could accelerate osteo-/angiogenic differentiation of bone mesenchymal stem cells (BMSCs) and meanwhile reprogram macrophages to establish a favorable osteoimmune microenvironment. In vivo experiments further demonstrated that SGC scaffolds could efficiently stimulate bone repair and create a regeneration-friendly osteoimmune microenvironment. Mechanistically, we discovered that SGC scaffolds may achieve immune reprogramming in macrophages through a decrease in the expression of Smad6 and Smad7, both of which participate in the transforming growth factor-β (TGF-β) signaling pathway.

CONCLUSION

Overall, this study demonstrated the clinical potential of the SGC scaffold due to its favorable pro-osteo-/angiogenic and osteoimmunomodulatory properties. In addition, it is a promising strategy to develop novel bone repair biomaterials by taking osteoinduction and osteoimmune microenvironment remodeling functions into account.

Targeting Signalling Pathways in Chronic Wound Healing

Chronic wounds fail to achieve complete closure and are an economic burden to healthcare systems due to the limited treatment options and constant medical attention. Chronic wounds are characterised by dysregulated signalling pathways. Research has focused on naturally derived compounds, stem-cell-based therapy, small molecule drugs, oligonucleotide delivery nanoparticles, exosomes and peptide-based platforms. The phosphoinositide-3-kinase (PI3K)/protein kinase B (AKT), Wingless-related integration (Wnt)/β-catenin, transforming growth factor-β (TGF-β), nuclear factor erythroid 2-related factor 2 (Nrf2), Notch and hypoxia-inducible factor 1 (HIF-1) signalling pathways have critical roles in wound healing by modulating the inflammatory, proliferative and remodelling phases. Moreover, several regulators of the signalling pathways were demonstrated to be potential treatment targets. In this review, the current research on targeting signalling pathways under chronic wound conditions will be discussed together with implications for future studies.

Peptide TK-HR from the Skin of Chinese Folk Medicine Frog Hoplobatrachus Rugulosus Accelerates Wound Healing via the Activation of the Neurokinin-1 Receptor

Wound healing is a complex process and remains a considerable challenge in clinical trials due to the lack of ideal therapeutic drugs. Here, a new peptide TK-HR identified from the skin of the frog Hoplobatrachus rugulosus was tested for its ability to heal cutaneous wounds in mice. Topical application of TK-HR at doses of 50-200 μg/mL significantly accelerated wound closure without causing any adverse effects in the animals. In vitro and in vivo investigations proved the regulatory role of the peptide on neutrophils, macrophages, keratinocytes, and vein endothelial cells involved in the inflammatory, proliferative, and remodeling phases of wound healing. Notably, TK-HR activated the MAPK and TGF-β-Smad signaling pathways by acting on NK1R in RAW264.7 cells and mice. The current work has identified that TK-HR is a potent wound healing regulator that can be applied for the treatment of wounds, including diabetic foot ulcers and infected wounds, in the future.

M2 macrophage polarization: a potential target in pain relief

Pain imposes a significant urden on patients, affecting them physically, psychologically, and economically. Despite numerous studies on the pathogenesis of pain, its clinical management remains suboptimal, leading to the under-treatment of many pain patients. Recently, research on the role of macrophages in pain processes has been increasing, offering potential for novel therapeutic approaches. Macrophages, being indispensable immune cells in the innate immune system, exhibit remarkable diversity and plasticity. However, the majority of research has primarily focused on the contributions of M1 macrophages in promoting pain. During the late stage of tissue damage or inflammatory invasion, M1 macrophages typically transition into M2 macrophages. In recent years, growing evidence has highlighted the role of M2 macrophages in pain relief. In this review, we summarize the mechanisms involved in M2 macrophage polarization and discuss their emerging roles in pain relief. Notably, M2 macrophages appear to be key players in multiple endogenous pathways that promote pain relief. We further analyze potential pathways through which M2 macrophages may alleviate pain.

Current status and progress in research on dressing management for diabetic foot ulcer

Diabetic foot ulcer (DFU) is a major complication of diabetes and is associated with a high risk of lower limb amputation and mortality. During their lifetime, 19%-34% of patients with diabetes can develop DFU. It is estimated that 61% of DFU become infected and 15% of those with DFU require amputation. Furthermore, developing a DFU increases the risk of mortality by 50%-68% at 5 years, higher than some cancers. Current standard management of DFU includes surgical debridement, the use of topical dressings and wound decompression, vascular assessment, and glycemic control. Among these methods, local treatment with dressings builds a protective physical barrier, maintains a moist environment, and drains the exudate from DFU wounds. This review summarizes the development, pathophysiology, and healing mechanisms of DFU. The latest research progress and the main application of dressings in laboratory and clinical stage are also summarized. The dressings discussed in this review include traditional dressings (gauze, oil yarn, traditional Chinese medicine, and others), basic dressings (hydrogel, hydrocolloid, sponge, foam, film agents, and others), bacteriostatic dressings, composite dressings (collagen, nanomaterials, chitosan dressings, and others), bioactive dressings (scaffold dressings with stem cells, decellularized wound matrix, autologous platelet enrichment plasma, and others), and dressings that use modern technology (3D bioprinting, photothermal effects, bioelectric dressings, microneedle dressings, smart bandages, orthopedic prosthetics and regenerative medicine). The dressing management challenges and limitations are also summarized. The purpose of this review is to help readers understand the pathogenesis and healing mechanism of DFU, help physicians select dressings correctly, provide an updated overview of the potential of biomaterials and devices and their application in DFU management, and provide ideas for further exploration and development of dressings. Proper use of dressings can promote DFU healing, reduce the cost of treating DFU, and reduce patient pain.

Eucommia lignans alleviate the progression of diabetic nephropathy through mediating the AR/Nrf2/HO-1/AMPK axis in vivo and in vitro

Lignans derived from Eucommia ulmoides Oliver (Eucommia lignans) inhibit the progression of inflammatory diseases, while their effect on the progression of diabetic nephropathy (DN) remained unclear. This work was designed to assess the function of Eucommia lignans in DN. The major constituents of Eucommia lignans were analyzed by UPLC-Q-TOF-MS/MS. The binding between Eucommia lignans and aldose reductase (AR) was predicted by molecular docking. Eucommia lignans (200, 100, and 50 mg·kg^-1) were used in model animals to evaluate their renal function changes. Rat glomerular mesangial cells (HBZY-1) were transfected with sh-AR, sh-AMPK, and oe-AR in the presence of high glucose (HG) or HG combined with Eucommia lignans to evaluate whether Eucommia lignans affected HG-induced cell injury and mitochondrial dysfunction through the AR/Nrf2/HO-1/AMPK axis. Eucommia lignans significantly attenuated the progression of DN in vivo. Eucommia lignans notably reversed HG-induced upregulation of inflammatory cytokines and mitochondrial injury, while downregulating the levels of Cyto c, caspase 9, AR, and NOX4 in HBZY-1 cells. In contrast, HG-induced downregulation of Nrf2, HO-1 and p-AMPKα levels were abolished by Eucommia lignans. Meanwhile, knockdown of AR exerted similar therapeutic effect of Eucommia lignans on DN progression, and AR overexpression reversed the effect of Eucommia lignans. Eucommia lignans alleviated renal injury through the AR/Nrf2/HO-1/AMPK axis. Thus, these findings might provide evidence for the use of Eucommia lignans in treating DN.

High glucose-induced STING activation inhibits diabetic wound healing through promoting M1 polarization of macrophages

Diabetic wound (DW) is characterized by elevated pro-inflammatory cytokines and cellular dysfunction consistent with elevated reactive oxygen species (ROS) levels. Recent advances in immunology have dissected molecular pathways involved in the innate immune system where cytoplasmic DNA can trigger STING-dependent inflammatory responses and play an important role in metabolic-related diseases. We investigated whether STING regulates inflammation and cellular dysfunction in DW healing. We found that STING and M1 macrophages were increased in wound tissues from DW in patients and mice and delayed the wound closure. We also noticed that the massively released ROS in the High glucose (HG) environment activated STING signaling by inducing the escape of mtDNA to the cytoplasm, inducing macrophage polarization into a pro-inflammatory phenotype, releasing pro-inflammatory cytokines, and exacerbating endothelial cell dysfunction. In Conclusion, mtDNA-cGAS-STING pathway activation under diabetic metabolic stress is an important mechanism of DW refractory healing. While using STING gene-edited macrophages for wound treatment by cell therapy can induce the polarization of wound macrophages from pro-inflammatory M1 to anti-inflammatory M2, promote angiogenesis, and collagen deposition to accelerate DW healing. STING may be a promising therapeutic target for DW.

Therapeutic role of growth factors in treating diabetic wound

Wounds in diabetic patients, especially diabetic foot ulcers, are more difficult to heal compared with normal wounds and can easily deteriorate, leading to amputation. Common treatments cannot heal diabetic wounds or control their many complications. Growth factors are found to play important roles in regulating complex diabetic wound healing. Different growth factors such as transforming growth factor beta 1, insulin-like growth factor, and vascular endothelial growth factor play different roles in diabetic wound healing. This implies that a therapeutic modality modulating different growth factors to suit wound healing can significantly improve the treatment of diabetic wounds. Further, some current treatments have been shown to promote the healing of diabetic wounds by modulating specific growth factors. The purpose of this study was to discuss the role played by each growth factor in therapeutic approaches so as to stimulate further therapeutic thinking.

Macrophage polarization in diabetic wound healing

Impaired wound healing is one of the severe complications of diabetes. Macrophages have been shown to play a vital role in wound healing. In different wound environments, macrophages are classified into two phenotypes: classically activated macrophages and alternatively activated macrophages. Dysregulation of macrophage phenotypes leads to severely impaired wound healing in diabetes. Particularly, uncontrolled inflammation and abnormal macrophage phenotype are important reasons hindering the closure of diabetic wounds. This article reviews the functions of macrophages at various stages of wound healing, the relationship between macrophage phenotypic dysregulation and diabetic wound healing and the mechanism of macrophage polarization in diabetic wound healing. New therapeutic drugs targeting phagocyte polarization to promote the healing of diabetic wounds might provide a new strategy for treating chronic diabetic wound healing.