Mast Cells in Diabetes and Diabetic Wound Healing

The evolving role of mast cells in wound healing: insights from recent research and diverse models

Chronic wounds significantly burden health care systems worldwide, requiring novel strategies to ease their impact. Many physiological processes underlying wound healing are well studied but the role of mast cells remains controversial. Mast cells are innate immune cells and play an essential role in barrier function by inducing inflammation to defend the host against chemical irritants and infections, among others. Many mast cell-derived mediators have proposed roles in wound healing; however, in vivo evidence using mouse models has produced conflicting results. Recently, studies involving more complex wound models such as infected wounds, diabetic wounds and wounds healing under psychological stress suggest that mast cells play critical roles in these processes. This review briefly summarizes the existing literature regarding mast cells in normal wounds and the potential reasons for the contradictory results. Focus will be placed on examining more recent work emerging in the last 5 years that explores mast cells in more complex systems of wound healing, including infection, psychological stress and diabetes, with a discussion of how these discoveries may inspire future work in the field.

Hypoxic microenvironment promotes diabetic wound healing by polarizing macrophages to the M2 phenotype in vivo

BACKGROUND

In diabetic wounds, M2 polarization of macrophages regulates the transition from an inflammatory phase to a proliferative phase. Prior investigations have demonstrated the potential of deferoxamine (DFO) in creating a localized hypoxic microenvironment, which could stimulate angiogenesis by promoting vascular endothelial growth factor (VEGF) secretion in diabetic wound healing. Nevertheless, there is still no clear information on whether this chemically induced hypoxic microenvironment modulates macrophage polarization to promote diabetic wound healing.

METHODS

The 18 diabetic mice were randomly divided into three groups: a control group (n = 6), a 100µM DFO group (n = 6), and a 200µM DFO group (n = 6). Subsequently, a full-thickness wound with a diameter of 1.00 cm was created on the dorsal region of the diabetic mice. Observe wound closure regularly during treatment. At the end of the observation, tissue specimens were collected for a series of experiments and analyses, including hematoxylin and eosin (H&E), Masson, immunofluorescent, and immunohistochemical staining. The role and mechanism of DFO in regulating macrophage polarization were studied using RAW264.7 cells.

RESULTS

In comparison to the control group, the administration of DFO notably facilitates wound healing in diabetic mice. In diabetic wounds, DFO increases blood supply by upregulating VEGF, which promotes angiogenesis. Additionally, The expression of HSP70 and CD206 were also upregulated by DFO in both vivo and in vitro, while iNOS expression was downregulated. Additionally, knk437 inhibited the expression of HSP70 in RAW264.7 cells, resulting in a reduction of M2 polarization and an increase in M1 polarization.

CONCLUSION

The induction of a hypoxic microenvironment by DFO has been found to exert a substantial influence on the process of diabetic wound healing. DFO treatment enhances the capacity of diabetic wounds to stimulate angiogenesis and modulate macrophage polarization that may be associated with HSP70 expression, thereby expediting the transition of these wounds from an inflammatory to a proliferative state.

Revealing the molecular mechanisms in wound healing and the effects of different physiological factors including diabetes, age, and stress

Wounds are the common fates in various microbial infections and physical damages including accidents, surgery, and burns. In response, a healthy body with a potent immune system heals that particular site within optimal time by following the coagulation, inflammation, proliferation, and remodeling phenomenon. However, certain malfunctions in the body due to various diseases particularly diabetes and other physiological factors like age, stress, etc., prolong the process of wound healing through various mechanisms including the Akt, Polyol, and Hexosamine pathways. The current review thoroughly explains the wound types, normal wound healing mechanisms, and the immune system's role. Moreover, the mechanistic role of diabetes is also elaborated comprehensively.

Identifying and Validating Extracellular Matrix-Related Gene CTSH in Diabetic Foot Ulcer Using Bioinformatics and Machine Learning

Background

Diabetic foot ulcer (DFU) is a serious clinical problem with high amputation and mortality rates, yet there is a lack of desirable therapy. While the extracellular matrix (ECM) contributes significantly to wound healing, ECM-related biomarker for DFU is still unknown. The study was designed to identify ECM-related biomarker in DFU using bioinformatics and machine learning and validate it in STZ-induced mice models.

Methods

GSE80178 and GSE134431 microarray datasets were fetched from the GEO database, and differentially expressed genes (DEGs) analysis was performed, respectively. By analyzing DEGs and ECM genes, we identified ECM-related DEGs, and functional enrichment analysis was conducted. Subsequently, three machine learning algorithms (LASSO, RF and SVM-RFE) were applied to filter ECM-related DEGs to identify key ECM-related biomarkers. Next, we conducted immune infiltration analysis, GSEA, and correlation analysis to explore the hub gene underlying mechanism. A lncRNA-miRNA-mRNA and drug regulatory network were constructed. Finally, we validated the key ECM-related biomarker in STZ-induced mice models.

Results

One hundred and forty-five common DEGs in adult DFU between the two datasets were identified. Taking the intersection of 145 common DEGs and 964 ECM genes, we identified 13 ECM-related DEGs. Thirteen ECM-related DEGs were mainly enriched in pathways associated with tissue remodeling, inflammation and defense against infectious agents. Ultimately, CTSH was identified as the key ECM-related biomarker. CTSH was associated with difference immune cells during the occurrence and development of DFU, and it influenced hedgehog, IL-17 and TNF signaling pathway. Additionally, CTSH expression is correlated with many ECM- and immune-related genes. A lncRNA-miRNA-mRNA and drug regulatory network were constructed with 10 lncRNAs, 2 miRNAs, CTSH and 1 drug. Finally, CTSH was validated as a key biomarker for DFU in animal models.

Conclusion

Our study found that CTSH can be used for both diagnostic and prognostic purposes and might be a potential therapeutic target.

Phytoconstituents as modulators of NF-κB signalling: Investigating therapeutic potential for diabetic wound healing

The NF-κB pathway plays a pivotal role in impeding the diabetic wound healing process, contributing to prolonged inflammation, diminished angiogenesis, and reduced proliferation. In contrast to modern synthetic therapies, naturally occurring phytoconstituents are well-studied inhibitors of the NF-κB pathway that are now attracting increased attention in the context of diabetic wound healing because of lower toxicity, better safety and efficacy, and cost-effectiveness. This study explores recent research on phytoconstituent-based therapies and delve into their action mechanisms targeting the NF-κB pathway and potential for assisting effective healing of diabetic wounds. For this purpose, we have carried out surveys of recent literature and analyzed studies from prominent databases such as Science Direct, Scopus, PubMed, Google Scholar, EMBASE, and Web of Science. The classification of phytoconstituents into various categorie such as: alkaloids, triterpenoids, phenolics, polyphenols, flavonoids, monoterpene glycosides, naphthoquinones and tocopherols. Noteworthy phytoconstituents, including Neferine, Plumbagin, Boswellic acid, Genistein, Luteolin, Kirenol, Rutin, Vicenin-2, Gamma-tocopherol, Icariin, Resveratrol, Mangiferin, Betulinic acid, Berberine, Syringic acid, Gallocatechin, Curcumin, Loureirin-A, Loureirin-B, Lupeol, Paeoniflorin, and Puerarin emerge from these studies as promising agents for diabetic wound healing through the inhibition of the NF-κB pathway. Extensive research on various phytoconstituents has revealed how they modulate signalling pathways, including NF-κB, studies that demonstrate the potential for development of therapeutic phytoconstituents to assist healing of chronic diabetic wounds.

Modulating the immune system towards a functional chronic wound healing: A biomaterials and Nanomedicine perspective

Chronic non-healing wounds persist as a substantial burden for healthcare systems, influenced by factors such as aging, diabetes, and obesity. In contrast to the traditionally pro-regenerative emphasis of therapies, the recognition of the immune system integral role in wound healing has significantly grown, instigating an approach shift towards immunological processes. Thus, this review explores the wound healing process, highlighting the engagement of the immune system, and delving into the behaviors of innate and adaptive immune cells in chronic wound scenarios. Moreover, the article investigates biomaterial-based strategies for the modulation of the immune system, elucidating how the adjustment of their physicochemical properties or their synergistic combination with other agents such as drugs, proteins or mesenchymal stromal cells can effectively modulate the behaviors of different immune cells. Finally this review explores various strategies based on synthetic and biological nanostructures, including extracellular vesicles, to finely tune the immune system as natural immunomodulators or therapeutic nanocarriers with promising biophysical properties.

Topical delivery of insulin using novel organogel formulations: An approach for the management of diabetic wounds

Diabetes mellitus is a growing chronic form of diabetes, with lengthy health implications. It is predicted as poor diabetic wound recovery affects roughly 25% of all diabetes mellitus patients, frequently resulting in lower traumatic injury and severe external factors and emotional expenses. The insulin-resistant condition increases biofilm development, making diabetic wounds harder to treat. Nowadays, medical treatment and management of diabetic wounds, which have a significant amputation rate, a high-frequency rate, and a high death rate, have become a global concern. Topical formulations have played a significant part in diabetic wound management and have been developed to achieve a number of features. Because of its significant biocompatibility, moisture retention, and therapeutic qualities, topical insulin has emerged as an appealing and feasible wound healing process effector. With a greater comprehension of the etiology of diabetic wounds, numerous functionalized topical insulins have been described and shown good outcomes in recent years, which has improved some diabetic injuries. The healing of wounds is a physiological phenomenon that restores skin integrity and heals damaged tissues. Insulin, a powerful wound-healing factor, is also used in several experimental and clinical studies accelerate healing of diverse injuries.

Potential immune-related therapeutic mechanisms of multiple traditional Chinese medicines on type 2 diabetic nephropathy based on bioinformatics, network pharmacology and molecular docking

BACKGROUND

The prevalence of type 2 diabetic nephropathy (T2DN) ranges from 20 % to 40 % among individuals with type 2 diabetes. Multiple immune pathways play a pivotal role in the pathogenesis of T2DN. This study aimed to investigate the immunomodulatory effects of active ingredients derived from 14 traditional Chinese medicines (TCMs) on T2DN.

METHODS

By removing batch effect on the GSE30528 and GSE96804 datasets, we employed a combination of weighted gene co-expression network analysis, least absolute shrinkage and selection operator analysis, protein-protein interaction network analysis, and the CIBERSORT algorithm to identify the active ingredients of TCMs as well as potential hub biomarkers associated with immune cells. Functional analysis was conducted using Kyoto Encyclopedia of Genes and Genomes (KEGG), Gene Ontology (GO), and gene set variation analysis (GSVA). Additionally, molecular docking was employed to evaluate interactions between active ingredients and potential immunotherapy targets.

RESULTS

A total of 638 differentially expressed genes (DEGs) were identified in this study, comprising 5 hub genes along with 4 potential biomarkers. Notably, CXCR1, CXCR2, and FOS exhibit significant associations with immune cells while displaying robust or favorable affinities towards the active ingredients kaempferol, quercetin, and luteolin. Furthermore, functional analysis unveiled intricate involvement of DEGs, hub genes and potential biomarkers in pathways closely linked to immunity and diabetes.

CONCLUSION

The potential hub biomarkers and immunotherapy targets associated with immune cells of T2DN comprise CXCR1, CXCR2, and FOS. Furthermore, kaempferol, quercetin, and luteolin demonstrate potential immunomodulatory effects in modulating T2DN through the regulation of CXCR1, CXCR2, and FOS expression.

Recent advances in molecular mechanisms of skin wound healing and its treatments

The skin, being a multifaceted organ, performs a pivotal function in the complicated wound-healing procedure, which encompasses the triggering of several cellular entities and signaling cascades. Aberrations in the typical healing process of wounds may result in atypical scar development and the establishment of a persistent condition, rendering patients more vulnerable to infections. Chronic burns and wounds have a detrimental effect on the overall quality of life of patients, resulting in higher levels of physical discomfort and socio-economic complexities. The occurrence and frequency of prolonged wounds are on the rise as a result of aging people, hence contributing to escalated expenditures within the healthcare system. The clinical evaluation and treatment of chronic wounds continue to pose challenges despite the advancement of different therapeutic approaches. This is mainly owing to the prolonged treatment duration and intricate processes involved in wound healing. Many conventional methods, such as the administration of growth factors, the use of wound dressings, and the application of skin grafts, are used to ease the process of wound healing across diverse wound types. Nevertheless, these therapeutic approaches may only be practical for some wounds, highlighting the need to advance alternative treatment modalities. Novel wound care technologies, such as nanotherapeutics, stem cell treatment, and 3D bioprinting, aim to improve therapeutic efficacy, prioritize skin regeneration, and minimize adverse effects. This review provides an updated overview of recent advancements in chronic wound healing and therapeutic management using innovative approaches.

Mast Cells are Dependent on Glucose Transporter 1 (GLUT1) and GLUT3 for IgE-mediated Activation

Mast cells (MCs) are known to have a pathological impact in a variety of settings, in particular in allergic conditions. There is also limited evidence implicating MCs in diabetes, raising the possibility that MC function may be influenced by alterations in glucose levels. However, it is not known whether MCs are directly affected by elevated glucose concentrations. Moreover, it is not known which glucose transporters that are expressed by MCs, and whether MCs are dependent on glucose transporters for activation. Here we addressed these issues. We show that MCs express high levels of both glucose transporter 1 (GLUT1/Slc2A1) and GLUT3 (Slc2A3). Further, we show that the inhibition of either GLUT1 or GLUT3 dampens both MC degranulation and cytokine induction in response to IgE receptor crosslinking, and that combined GLUT1 and GLUT3 inhibition causes an even more pronounced inhibition of these parameters. In contrast, the inhibition of GLUT1 or GLUT3, or combined GLUT1 and GLUT3 inhibition, had less impact on the ability of the MCs to respond to activation via compound 48/80. Elevated glucose concentrations did not affect MC viability, and had no stimulatory effect on MC responses to either IgE receptor crosslinking or compound 48/80. Altogether, these findings reveal that MCs are strongly dependent on glucose transport via GLUT1 and/or GLUT3 for optimal responses towards IgE-mediated activation, whereas MC functionality is minimally affected by elevated glucose levels. Based on these findings, antagonists of GLUT1 and GLUT3 may be considered for therapeutic intervention in allergic conditions.

Deciphering the crosstalk between inflammation and biofilm in chronic wound healing: Phytocompounds loaded bionanomaterials as therapeutics

In terms of the economics and public health, chronic wounds exert a significant detrimental impact on the health care system. Bacterial infections, which cause the formation of highly resistant biofilms that elude standard antibiotics, are the main cause of chronic, non-healing wounds. Numerous studies have shown that phytochemicals are effective in treating a variety of diseases, and traditional medicinal plants often include important chemical groups such alkaloids, phenolics, tannins, terpenes, steroids, flavonoids, glycosides, and fatty acids. These substances are essential for scavenging free radicals which helps in reducing inflammation, fending off infections, and hastening the healing of wounds. Bacterial species can survive in chronic wound conditions because biofilms employ quorum sensing as a communication technique which regulates the expression of virulence components. Fortunately, several phytochemicals have anti-QS characteristics that efficiently block QS pathways, prevent drug-resistant strains, and reduce biofilm development in chronic wounds. This review emphasizes the potential of phytocompounds as crucial agents for alleviating bacterial infections and promoting wound healing by reducing the inflammation in chronic wounds, exhibiting potential avenues for future therapeutic approaches to mitigate the healthcare burden provided by these challenging conditions.

Single-cell analysis of age-related changes in leukocytes of diabetic mouse hindpaws

Complications associated with Type 1 and Type 2 diabetes, such as diabetic peripheral neuropathy and diabetic foot ulcers, are a growing health-care concern. In addition, this concern increases as diabetic patients age due to their increased susceptibility to complications. To address this growing problem, it is important to understand fluctuations in physiology which lead to pathological changes associated with the metabolic disturbances of diabetes. Our study explores dysregulation of immune cell populations in the hindpaws of healthy and diabetic mice at 12 and 21 weeks of age using single-cell RNA sequencing to provide insight into immune disruptions occurring in the distal limb during chronic diabetes. In 21-week-old Leprdb/db mice, increases were seen in mast cells/basophils, dermal γδ T cells, heterogeneous T cells, and Type 2 innate lymphoid cells. In addition, macrophages represented the largest cluster of immune cells and showed the greatest increase in genes associated with immune-specific pathways. Sub-clustering of macrophages revealed a bias toward angiogenic Lyve1+MHCIIlo macrophages in the hindpaws of 21-week-old diabetic mice, which corresponded to an increase in Lyve1+ macrophages in the hindpaws of 21-week-old diabetic mice on histology. Our results show that in Type 2 diabetes, the immunological function and phenotype of multiple immune cell types shift not only with metabolic disturbance, but also with duration of disease, which may explain the increased susceptibility to pathologies of the distal limb in patients with more chronic diabetes.

New insights into the role of immunity and inflammation in diabetic kidney disease in the omics era

Diabetic kidney disease (DKD) is becoming the leading cause of chronic kidney disease, especially in the industrialized world. Despite mounting evidence has demonstrated that immunity and inflammation are highly involved in the pathogenesis and progression of DKD, the underlying mechanisms remain incompletely understood. Substantial molecules, signaling pathways, and cell types participate in DKD inflammation, by integrating into a complex regulatory network. Most of the studies have focused on individual components, without presenting their importance in the global or system-based processes, which largely hinders clinical translation. Besides, conventional technologies failed to monitor the different behaviors of resident renal cells and immune cells, making it difficult to understand their contributions to inflammation in DKD. Recently, the advancement of omics technologies including genomics, epigenomics, transcriptomics, proteomics, and metabolomics has revolutionized biomedical research, which allows an unbiased global analysis of changes in DNA, RNA, proteins, and metabolites in disease settings, even at single-cell and spatial resolutions. They help us to identify critical regulators of inflammation processes and provide an overview of cell heterogeneity in DKD. This review aims to summarize the application of multiple omics in the field of DKD and emphasize the latest evidence on the interplay of inflammation and DKD revealed by these technologies, which will provide new insights into the role of inflammation in the pathogenesis of DKD and lead to the development of novel therapeutic approaches and diagnostic biomarkers.

Genetic Changes in Mastocytes and Their Significance in Mast Cell Tumor Prognosis and Treatment

Mast cell tumors are a large group of diseases occurring in dogs, cats, mice, as well as in humans. Systemic mastocytosis (SM) is a disease involving the accumulation of mast cells in organs. KIT gene mutations are very often seen in abnormal mast cells. In SM, high KIT/CD117 expression is observed; however, there are usually no KIT gene mutations present. Mastocytoma (MCT)-a form of cutaneous neoplasm-is common in animals but quite rare in humans. KIT/CD117 receptor mutations were studied as the typical changes for human mastocytosis. In 80% of human cases, the KIT gene substitution p.D816H was present. In about 25% of MCTs, metastasis was observed. Changes in the gene expression of certain genes, such as overexpression of the DNAJ3A3 gene, promote metastasis. In contrast, the SNORD93 gene blocks the expression of metastasis genes. The panel of miR-21-5p, miR-379, and miR-885 has a good efficiency in discriminating healthy and MCT-affected dogs, as well as MCT-affected dogs with and without nodal metastasis. Further studies on the pathobiology of mast cells can lead to clinical improvements, such as better MCT diagnosis and treatment. Our paper reviews studies on the topic of mast cells, which have been carried out over the past few years.

Impact of a High-Fat Diet at a Young Age on Wound Healing in Mice

As the prevalence of juvenile-onset obesity rises globally, the multitude of related health consequences gain significant importance. In this context, obesity is associated with impaired cutaneous wound healing. In experimental settings, mice are the most frequently used model for investigating the effect of high-fat diet (HFD) chow on wound healing in wild-type or genetically manipulated animals, e.g., diabetic ob/ob and db/db mice. However, these studies have mainly been performed on adult animals. Thus, in the present study, we introduced a mouse model for a juvenile onset of obesity. We exposed 4-week-old mice to an investigational feeding period of 9 weeks with an HFD compared to a regular diet (RD). At a mouse age of 13 weeks, we performed excisional and incisional wounding and measured the healing rate. Wound healing was examined by serial photographs with daily wound size measurements of the excisional wounds. Histology from incisional wounds was performed to quantify granulation tissue (thickness, quality) and angiogenesis (number of blood vessels per mm2). The expression of extracellular matrix proteins (collagen types I/III/IV, fibronectin 1, elastin), inflammatory cytokines (MIF, MIF-2, IL-6, TNF-α), myofibroblast differentiation (α-SMA) and macrophage polarization (CD11c, CD301b) in the incisional wounds were evaluated by RT-qPCR and by immunohistochemistry. There was a marked delay of wound closure in the HFD group with a decrease in granulation tissue quality and thickness. Additionally, inflammatory cytokines (MIF, IL-6, TNF-α) were significantly up-regulated in HFD- when compared to RD-fed mice measured at day 3. By contrast, MIF-2 and blood vessel expression were significantly reduced in the HFD animals, starting at day 1. No significant changes were observed in macrophage polarization, collagen expression, and levels of TGF-β1 and PDGF-A. Our findings support that an early exposition to HFD resulted in juvenile obesity in mice with impaired wound repair mechanisms, which may be used as a murine model for obesity-related studies in the future.

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.

Neutrophil heterogeneity and aging: implications for COVID-19 and wound healing

Neutrophils play a critical role in the immune response to infection and tissue injury. However, recent studies have shown that neutrophils are a heterogeneous population with distinct subtypes that differ in their functional properties. Moreover, aging can alter neutrophil function and exacerbate immune dysregulation. In this review, we discuss the concept of neutrophil heterogeneity and how it may be affected by aging. We then examine the implications of neutrophil heterogeneity and aging for COVID-19 pathogenesis and wound healing. Specifically, we summarize the evidence for neutrophil involvement in COVID-19 and the potential mechanisms underlying neutrophil recruitment and activation in this disease. We also review the literature on the role of neutrophils in the wound healing process and how aging and neutrophil heterogeneity may impact wound healing outcomes. Finally, we discuss the potential for neutrophil-targeted therapies to improve clinical outcomes in COVID-19 and wound healing.

δ-Tocotrienol preconditioning improves the capability of bone marrow-derived mesenchymal stem cells in promoting wound healing by inhibiting BACH1-related ferroptosis

Wound healing is a complex physiological process for maintaining skin integrity after a wound. Bone marrow-derived mesenchymal stem cells (BMSCs) are excellent cellular candidates for wound healing, which could be enhanced by exogenous stimulation. We aimed to explore the role of δ-Tocotrienol (δ-TT) in BMSC ability of wound healing. Firstly, transcriptome and single-cell analysis were used to explore the genes and pathways related to ferroptosis in wound tissues. In vitro, cell proliferation, migration, and angiogenesis of δ-TT-BMSCs were detected. In addition, qRT-PCR and immunofluorescence (IF) were applied for observing the promoting wound healing ability of δ-TT-BMSC conditioned medium (CM) on NIH-3T3 and PAM-212 cells. The level of ferroptosis was determined by the mitochondrial membrane potential and total/lipid reactive oxygen species (ROS) in the cells and the morphological changes of mitochondria were observed by transmission electron microscope. The BTB and CNC homology 1 (BACH1) expression and activation of the PI3K/AKT signaling pathway were detected by IF and western blot (WB). The effect of δ-TT-BMSCs on wound healing was observed in vivo. The regulatory mechanism of δ-TT-BMSCs on ferroptosis was verified by IHC and IF staining. In vitro, δ-TT-BMSCs declined the level of lipid ROS in NIH-3T3 and PAM-212 cells and enhanced mitochondrial membrane potential. In vivo, δ-TT-BMSCs promoted wound healing in mice by decreasing ferroptosis. In terms of mechanism, δ-TT-BMSCs inhibited the expression of BACH1 and activated PI3K/AKT signaling pathway. This study demonstrated the ability of δ-TT-BMSCs to promote wound healing by inhibiting BACH1-related ferroptosis. In addition, PI3K/AKT signaling pathway was activated by δ-TT-BMSCs and could be involved in wound healing. δ-TT-BMSCs might be a promising strategy for treating wounds.

Cutaneous changes in diabetic patients: Primed for aberrant healing?

Cutaneous manifestations affect most patients with diabetes mellitus, clinically presenting with numerous dermatologic diseases from xerosis to diabetic foot ulcers (DFUs). Skin conditions not only impose a significantly impaired quality of life on individuals with diabetes but also predispose patients to further complications. Knowledge of cutaneous biology and the wound healing process under diabetic conditions is largely limited to animal models, and studies focusing on biology of the human condition of DFUs remain limited. In this review, we discuss the critical molecular, cellular, and structural changes to the skin in the hyperglycaemic and insulin-resistant environment of diabetes with a focus specifically on human-derived data. Elucidating the breadth of the cutaneous manifestations coupled with effective diabetes management is important for improving patient quality of life and averting future complications including wound healing disorders.

Biological macromolecules-based nanoformulation in improving wound healing and bacterial biofilm-associated infection: A review

A chronic wound is a serious complication associated with diabetes mellitus and is difficult to heal due to high glucose levels, oxidative stress, and biofilm-associated microbial infection. The structural complexity of microbial biofilm makes it impossible for antibiotics to penetrate the matrix, hence conventional antibiotic therapies became ineffective in clinical settings. This demonstrates an urgent need to find safer alternatives to reduce the prevalence of chronic wound infection associated with microbial biofilm. A novel approach to address these concerns is to inhibit biofilm formation using biological-macromolecule based nano-delivery system. Higher drug loading efficiency, sustained drug release, enhanced drug stability, and improved bioavailability are advantages of employing nano-drug delivery systems to prevent microbial colonization and biofilm formation in chronic wounds. This review covers the pathogenesis, microbial biofilm formation, and immune response to chronic wounds. Furthermore, we also focus on macromolecule-based nanoparticles as wound healing therapies to reduce the increased mortality associated with chronic wound infections.

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.

Mast Cell Deficiency in Mice Attenuates Insulin Phenolic Preservative-Induced Inflammation

One major obstacle that limits the lifespan of insulin infusion pumps is surmounting the tissue site reaction at the device implantation site. All commercial insulin formulations contain insulin phenolic preservatives (IPPs) designed to ensure insulin protein stability and prolong shelf-life. However, our laboratory demonstrated that these preservatives are cytotoxic and induce inflammation. Mature mast cells (MCs) reside in cutaneous tissue and are one of the first responders to an epidermal breach. Upon activation, MCs release proinflammatory and immunomodulatory prepacked mediators that exacerbate these inflammatory reactions. Thus, we hypothesized that once the epidermis is breached, cutaneous MCs are triggered inciting the inflammatory response to IPP-induced inflammation. This hypothesis was pursued utilizing our modified in vivo mouse air pouch model, including a c-kit dependent (C57BL/6J-kitW-sh/W-sh) and a c-kit independent (Cpa3-Cre; Mcl-1fl/fl) MC-deficient mouse model. Leukocytes were quantified in the mouse air pouch lavage fluid following flow cytometry analysis for IPP infusion under three different states, insulin-containing phenolic preservatives (Humalog®), insulin preservatives alone, and normal saline as a control. The air pouch wall was assessed using histopathological evaluations. Flow cytometry analysis demonstrated a statistically significant difference in inflammatory cell recruitment for both MC-deficient mouse models when compared to the control strain including infused control saline. Significantly less inflammation was observed at the site of infusion for the MC-deficient strains compared to the control strain. Overall, concordant results were obtained in both mouse types, C57Bl6-kitW-sh/W-sh and Cpa3-Cre; Mcl-1fl/fl. These findings in multiple model systems support the conclusion that MCs have important or possible unique roles in IPP-induced inflammation.

Corylin accelerated wound healing through SIRT1 and PI3K/AKT signaling: a candidate remedy for chronic non-healing wounds

Introduction: Chronic non-healing wound is a considerable clinical challenge and research into the discovery of novel pro-healing agents is underway as existing therapeutic approaches cannot sufficiently meet current needs. Method: We studied the effects of corylin in cell line fibroblasts and macrophages by Western blots, PCR, Flow cytometry assay, Immunofluorescence. Results: We showed that corylin, a main flavonoid extracted from Psoralea corylifolia L, reduced inflammatory responses, promoted collagen deposition, and accelerated the healing of full-thickness skin wounds in mice. Exploration of the underlying mechanisms showed that corylin activated the PI3K/AKT signaling, leading to fibroblasts' migration, proliferation, and scratch healing. Corylin also activated sirtuin 1 (SIRT1) signaling, enhanced the deacetylation and cytoplasmic translocation of NF-κB p65, and therefore reduced lipopolysaccharide (LPS)-induced inflammatory responses in macrophages. Furthermore, inhibition of PI3K/AKT and sirtuin 1 pathway with LY294002 and EX527 prevent the therapeutic potency of corylin against chronic wounds. Conclusion: In summary, our results suggested that corylin may be a candidate for the development of novel pro-healing agents.

Mechanisms of Nrf2 and NF-κB pathways in diabetic wound and potential treatment strategies

The issue of delayed wound healing or nonhealing in diabetic patients presents a challenge for modern medicine. A number of attempts have been made to understand the mechanisms behind diabetic wound. In a hyperglycemic environment, increased intracellular reactive oxygen species (ROS) disturb the balance between oxidation and antioxidant, causing the wound environment to deteriorate. It has been established that the nuclear factor E2-related factor 2 (Nrf2) and nuclear factor-kappa B (NF-κB) pathways play an important role in regulating inflammation and oxidative stress. Several potential treatment strategies involving Nrf2 and/or NF-κB pathways have been explored in previous studies. Hence, we analyzed mechanisms and changes in Nrf2 and NF-κB pathways in response to oxidative stress and inflammation in diabetic environment. Additionally, we reviewed potential treatment strategies from the past five years for diabetic wound by Nrf2 and/or NF-κB pathways, including receptor agonists, vitamins, hormones, exosomes, drugs, plants, and biomaterials. It may be useful to develop drugs to promote diabetic wound healing.

Molecular Pathophysiology of Chronic Wounds: Current State and Future Directions

Venous leg ulcers, diabetic foot ulcers, and pressure ulcers are complex chronic wounds with multifactorial etiologies that are associated with high patient morbidity and mortality. Despite considerable progress in deciphering the pathologies of chronic wounds using "omics" approaches, considerable gaps in knowledge remain, and current therapies are often not efficacious. We provide a comprehensive overview of current understanding of the molecular mechanisms that impair healing and current knowledge on cell-specific dysregulation including keratinocytes, fibroblasts, immune cells, endothelial cells and their contributions to impaired reepithelialization, inflammation, angiogenesis, and tissue remodeling that characterize chronic wounds. We also provide a rationale for further elucidation of ulcer-specific pathologic processes that can be therapeutically targeted to shift chronic nonhealing to acute healing wounds.

The Potential of Topical Therapy for Diabetic Wounds: A Narrative Review

The rising prevalence of diabetes mellitus brings with it a rise in the occurrence of several complications of the disease such as chronic non-healing wounds. Diabetics are more prone to developing chronic wounds due to complications like peripheral neuropathy, poor foot care, hyperglycaemia and peripheral vascular diseases. The aim of this review is to discuss the various imbalances in the cytokine environment of diabetic wounds and to explore the developments in their management with an emphasis on agents that may be used topically to aid the healing process of chronic wounds. A systematic search was conducted on Scopus, PubMed and Google Scholar and relevant articles were shortlisted. We conclude that increased blood sugar impairs most phases of wound healing in several ways. Supplementary therapy with either topical or systemic cytokines is shown to promote wound healing in a diabetic wound.

Advances in Zebrafish for Diabetes Mellitus with Wound Model

Diabetic foot ulcers cause great suffering and are costly for the healthcare system. Normal wound healing involves hemostasis, inflammation, proliferation, and remodeling. However, the negative factors associated with diabetes, such as bacterial biofilms, persistent inflammation, impaired angiogenesis, inhibited cell proliferation, and pathological scarring, greatly interfere with the smooth progress of the entire healing process. It is this impaired wound healing that leads to diabetic foot ulcers and even amputations. Therefore, drug screening is challenging due to the complexity of damaged healing mechanisms. The establishment of a scientific and reasonable animal experimental model contributes significantly to the in-depth research of diabetic wound pathology, prevention, diagnosis, and treatment. In addition to the low cost and transparency of the embryo (for imaging transgene applications), zebrafish have a discrete wound healing process for the separate study of each stage, resulting in their potential as the ideal model animal for diabetic wound healing in the future. In this review, we examine the reasons behind the delayed healing of diabetic wounds, systematically review various studies using zebrafish as a diabetic wound model by different induction methods, as well as summarize the challenges and improvement strategies which provide references for establishing a more reasonable diabetic wound zebrafish model.

Wounds under diabetic milieu: The role of immune cellar components and signaling pathways

A major challenge in the field of diabetic wound healing is to confirm the body's intrinsic mechanism that could sense the immune system damage promptly and protect the wound from non-healing. Accumulating literature indicates that macrophage, a contributor to prolonged inflammation occurring at the wound site, might play such a role in hindering wound healing. Likewise, other immune cell dysfunctions, such as persistent neutrophils and T cell infection, may also lead to persistent oxidative stress and inflammatory reaction during diabetic wound healing. In this article, we discuss recent advances in the immune cellular components in wounds under the diabetic milieu, and the role of key signaling mechanisms that compromise the function of immune cells leading to persistent wound non-healing.

[Low level laser therapy: molecular mechanisms of anti-inflammatory and regenerative effects]

Laser therapy as a physiotherapeutic method has been successfully used for a long time in the treatment of various pathologies, but the action mechanisms of low level laser therapy (LLLT) remain understudied.

OBJECTIVE

To perform the analysis of published results of LLLT investigations, to describe the physical principles of photobiomodulation, its action mechanisms on various cells and tissues, therapeutic intervention and efficiency of the technique.

MATERIAL AND METHODS

The search of articles was done for the period from 2014 to 2022. The preference was given to the articles for the last 5 years in the PubMed database depending on keywords: low level laser therapy, photobiomodulation, exosomes, monocytes, macrophages.

RESULTS AND DISCUSSION

This article represents the current conceptions about the action mechanisms and reproduced effects of low level laser therapy, the photobiomodulation influence on the inflammation and reparative processes in human body by intervention on cells and their signal pathways. The discussion of research results and probable causes of conflicting data are performed, as well as the efficacy assessment of laser irradiation in different conditions and diseases is made.

CONCLUSION

Laser therapy has certain variety of advantages, among which: non-invasiveness and availability, long-term service of equipment, stable intensity of light radiation and the ability to use in various wavelength ranges. The technique efficacy was proven for a large number of diseases. However, for the successful application of photobiomodulation in clinical practice in current evidence-based medicine, additional investigations are necessary to determine the best dosimetric radiation parameters, as well as further study of action mechanisms on various human cells and tissues.

Mesenchymal stem cell-derived exosomes: The dawn of diabetic wound healing

Chronic wound healing has long been an unmet medical need in the field of wound repair, with diabetes being one of the major etiologies. Diabetic chronic wounds (DCWs), especially diabetic foot ulcers, are one of the most threatening chronic complications of diabetes. Although the treatment strategies, drugs, and dressings for DCWs have made great progress, they remain ineffective in some patients with refractory wounds. Stem cell-based therapies have achieved specific efficacy in various fields, with mesenchymal stem cells (MSCs) being the most widely used. Although MSCs have achieved good feedback in preclinical studies and clinical trials in the treatment of cutaneous wounds or other situations, the potential safety concerns associated with allogeneic/autologous stem cells and unknown long-term health effects need further attention and supervision. Recent studies have reported that stem cells mainly exert their trauma repair effects through paracrine secretion, and exosomes play an important role in intercellular communication as their main bioactive component. MSC-derived exosomes (MSC-Exos) inherit the powerful inflammation and immune modulation, angiogenesis, cell proliferation and migration promotion, oxidative stress alleviation, collagen remodeling imbalances regulation of their parental cells, and can avoid the potential risks of direct stem cell transplantation to a large extent, thus demonstrating promising performance as novel "cell-free" therapies in chronic wounds. This review aimed to elucidate the potential mechanism and update the progress of MSC-Exos in DCW healing, thereby providing new therapeutic directions for DCWs that are difficult to be cured using conventional therapy.

IL-1β/NF-κB signaling inhibits IGF-1 production via let-7f-5p in dendritic epidermal T cells

Dendritic epidermal T cells (DETCs) are the main source of insulin-like growth factor-1 (IGF-1) in epidermal tissue, which promote re-epithelialization and wound healing. In refractory wounds, IL-1β has been shown to activate NF-κB and suppress IGF-1 expression in DETCs. Nevertheless, the underlying mechanisms remain unclear. In this study, chromatin immunoprecipitation analysis revealed that IL-1β did not inhibit NF-κB binding to IGF-1 promoter, indicating that IL-1β/NF-κB may suppress IGF-1 expression by alternative mechanisms. MiRNAs negatively regulate gene expression predominantly by base pairing to the 3' untranslation region (UTR) of target mRNAs. Let-7f-5p, miR-1a-3p, and miR-98-5p have been identified as IGF-1-specific miRNAs that can bind directly to the 3'UTR of IGF-1 mRNA and dysregulate IGF-1 mRNA and protein levels. In IL-1β-treated epidermis around wounds or DETCs in vitro, NF-κB promoted the expression of let-7f-5p, and IGF-1 expression was impeded via NF-κB/let-7f-5p pathway. As pre-let-7f-5p, let-7f-1 is located in the 3'UTR of LOC118568094, and let-7f-2 is located in the intron of HUWE1. We discovered that NF-κB p65 bound to the promoters of LOC118568094 and HUWE1 to accelerate let-7f-5p expression, but NF-κB p65 did not affect the methylation levels of LOC118568094 and HUWE1 CpG islands. Injections of Let-7f-5p antagomir into IL-1β-treated and ischemic wound margins restored IGF-1 secretion in DETCs and promoted wound healing. In conclusion, we demonstrated that NF-κB signaling pathway activated by IL-1β could increase let-7f-5p expression to inhibit IGF-1 production in DETCs and delay wound healing. And let-7f-5p antagomir utilized in wound margin could effectively promote refractory wound healing.

A Shape-Adaptive Gallic Acid Driven Multifunctional Adhesive Hydrogel Loaded with Scolopin2 for Wound Repair

Wound healing is one of the major challenges in the biomedical fields. The conventional single drug treatment has unsatisfactory efficacy, and the drug delivery effectiveness is restricted by the short retention on the wound. Herein, we develop a multifunctional adhesive hydrogel that can realize robust adhesion, transdermal delivery, and combination therapy for wound healing. Multifunctional hydrogels (CS-GA-S) are mixed with chitosan-gallic acid (CS-GA), sodium periodate, and centipede peptide-scolopin2, which slowly releases scolopin2 in the layer of the dermis. The released scolopin2 induces the pro-angiogenesis of skin wounds and enables excellent antibacterial effects. Separately, GA as a natural reactive-oxygen-species-scavenger promotes antioxidation, and further enables excellent antibacterial effects and wet tissue adhesion due to a Schiff base and Michael addition reaction for accelerating wound healing. Once adhered to the wound, the precursor solution becomes both a physically and covalently cross-linked network hydrogel, which has potential advantages for wound healing with ease of use, external environment-isolating, and minimal tissue damage. The therapeutic effects of CS-GA-S on wound healing are demonstrated with the full thickness cutaneous wounds of a mouse model. The significant improvement of wound healing is achieved for mice treated with CS-GA-S. This preparation reduces wound system exposure, prolongs local drug residence time, and improves efficacy. Accordingly, with the incorporation of scolopin2 into the shape-adaptive CS-GA hydrogel, the composite hydrogel possesses multi-functions of mechanical adhesion, drug therapy, and skin wound healing. Overall, such an injectable or sprayable hydrogel plays an effective role in emergency wound treatment with the advantage of convenience and portability.

The combined use of photobiomodulation and curcumin-loaded iron oxide nanoparticles significantly improved wound healing in diabetic rats compared to either treatment alone

This experimental study examined the effects of curcumin-loaded iron oxide nanoparticles (CUR), photobiomodulation (PBM), and CUR + PBM treatments on mast cells (MC)s numbers and degranulation, inflammatory cells (macrophages, neutrophils), and wound strength in the last step of the diabetic wound repair process (maturation phase) in a rat model of type one diabetes mellitus (T1DM). T1DM was induced in 24 rats, and 1 month later, an excisional wound was created on each rat's back skin. The rats were then distributed into four groups: (1) untreated diabetic control group (UDCG); (2) rats treated with CUR (CUR); (3) rats exposed to PBM (890 nm, 80 Hz, 0.2 J/cm²) (PBM); (4) rats treated with CUR plus PBM (CUR + PBM). Fifteen days after surgery, skin tissue samples were taken for biomechanical and stereological evaluations. The biomechanical factor of maximum force was observed to be considerably improved in the CUR + PBM (p = 0.000), PBM (p = 0.014), and CUR (p = 0.003) groups compared to the UDCG. CUR + PBM, PBM, and CUR groups had significantly decreased total numbers of MC compared with the UDCG (all, p = 0.001). The results were significantly better in the CUR + PBM (p = 0.000) and PBM (p = 0.003) groups than in the CUR group. Inflammatory cell counts were significantly lower in the CUR + PBM, PBM, and CUR groups than in the UDCG (all, p = 0.0001). In all evaluating methods, the usage of CUR + PBM produced better results than the use of CUR or PBM alone (almost all tests, p = 0.0001). CUR + PBM, PBM, and CUR significantly improved the repair of diabetic skin wounds in type 1 DM rats through significant decreases of MC number, degranulation, and inflammatory cells as well as a noteworthy improvement in wound strength. The impact of CUR + PBM was superior to that of either PBM or CUR alone. It is suggested that CUR + PBM could be used as a MC stabilizer for the effective treatment of some related human diseases.

Effect of bromelain on mast cell numbers and degranulation in diabetic rat wound healing

OBJECTIVE

Many studies have revealed the prominent roles of mast cells in wound healing, including inflammatory reactions, angiogenesis and extracellular matrix reabsorption. In the present study, we aimed to assess the probable therapeutic features of bromelain on wound contraction and mast cell degranulation in wound healing in experimental diabetic animals.

METHOD

Male rats were grouped as control, vehicle and experiment. Skin wounds were generated in all groups. Treatments were applied with distilled water and with bromelain (BR) intraperitoneally in the vehicle and experimental groups, respectively. Following skin wound generation, animals were euthanised on days 3, 5, 7 and 15. We gathered 16,800 microscopic images to count the mast cells and degranulation level (Image J software). The wound contraction index was assessed both microscopically (Image J software) and macroscopically (time-lapse photography). The meshwork evaluation method was used to assess wound healing.

RESULTS

Time-lapse photography revealed that the BR significantly (p<0.05) accelerated wound contraction and healing. BR significantly (p<0.05) increased the total number of mast cells in all experimental groups on days 5 and 7. The count of grade III (degranulated) mast cells was reduced significantly (p<0.05) on days 5 and 7 in experimental groups compared to control and vehicle groups.

CONCLUSION

In this study, the rate of wound healing was accelerated considerably following BR administration. In addition, this agent decreased the count of degranulated mast cells, leading to wound contraction and healing.

The Emerging Role of Immune Cells and Targeted Therapeutic Strategies in Diabetic Wounds Healing

Poor wound healing in individuals with diabetes has long plagued clinicians, and immune cells play key roles in the inflammation, proliferation and remodeling that occur in wound healing. When skin integrity is damaged, immune cells migrate to the wound bed through the actions of chemokines and jointly restore tissue homeostasis and barrier function by exerting their respective biological functions. An imbalance of immune cells often leads to ineffective and disordered inflammatory responses. Due to the maladjusted microenvironment, the wound is unable to smoothly transition to the proliferation and remodeling stage, causing it to develop into a chronic refractory wound. However, chronic refractory wounds consistently lead to negative outcomes, such as long treatment cycles, high hospitalization rates, high medical costs, high disability rates, high mortality rates, and many adverse consequences. Therefore, strategies that promote the rational distribution and coordinated development of immune cells during wound healing are very important for the treatment of diabetic wounds (DW). Here, we explored the following aspects by performing a literature review: 1) the current situation of DW and an introduction to the biological functions of immune cells; 2) the role of immune cells in DW; and 3) existing (or undeveloped) therapies targeting immune cells to promote wound healing to provide new ideas for basic research, clinical treatment and nursing of DW.

The Problem of Wound Healing in Diabetes—From Molecular Pathways to the Design of an Animal Model

Chronic wounds are becoming an increasingly common clinical problem due to an aging population and an increased incidence of diabetes, atherosclerosis, and venous insufficiency, which are the conditions that impair and delay the healing process. Patients with diabetes constitute a group of subjects in whom the healing process is particularly prolonged regardless of its initial etiology. Circulatory dysfunction, both at the microvascular and macrovascular levels, is a leading factor in delaying or precluding wound healing in diabetes. The prolonged period of wound healing increases the risk of complications such as the development of infection, including sepsis and even amputation. Currently, many substances applied topically or systemically are supposed to accelerate the process of wound regeneration and finally wound closure. The role of clinical trials and preclinical studies, including research based on animal models, is to create safe medicinal products and ensure the fastest possible healing. To achieve this goal and minimize the wide-ranging burdens associated with conducting clinical trials, a correct animal model is needed to replicate the wound conditions in patients with diabetes as closely as possible. The aim of the paper is to summarize the most important molecular pathways which are impaired in the hyperglycemic state in the context of designing an animal model of diabetic chronic wounds. The authors focus on research optimization, including economic aspects and model reproducibility, as well as the ethical dimension of minimizing the suffering of research subjects according to the 3 Rs principle (Replacement, Reduction, Refinement).

A pharmacological approach assessing the role of mast cells in insulin infusion site inflammation

Background Extending the lifespan of subcutaneous insulin administration sets and infusion pumps requires overcoming unreliable insulin delivery induced by dermal reactions. All commercially available insulin formulations contain insulin phenolic preservatives (IPP), which stabilize the insulin molecule but result in unwanted cell and tissue toxicity. Mast cells, which are the first line of defense once the epithelium is breached, are particularly abundant beneath the skin surface. Thus, we hypothesize a sequence of events initiated by device insertion that activates skin mast cells (MC) that subsequently trigger neutrophil and monocyte/macrophage recruitment. The ensuing inflammatory response compromises effective insulin infusion therapy. Methods We employed a non-genetic, pharmacological approach to MC membrane stabilization using Cromolyn sodium (CS), which inhibits MC degranulation. These studies were conducted in our modified air pouch mouse model using non-diabetic and streptozotocin induced diabetic mice. We evaluated the impact of systemic CS through intraperitoneal injections, as well as the impact of local CS through co-infusion, on infusion catheter insertion and IPP-induced inflammation. Results CS at a concentration of 50 mg/kg minimized inflammation triggered in response to insulin phenolic preservatives present in standard insulin formulations. The resultant degree of tissue inflammation was comparable to that observed with saline injections. Conclusion Targeting MC has the potential to extend the longevity of insulin infusion sets by mitigating the inflammatory response. Future studies should be directed at employing other MC models, such as newer Cre/loxP mouse strains, to confirm the sentinel role of MC in insulin infusion therapy.

Reprograming the immune niche for skin tissue regeneration - From cellular mechanisms to biomaterials applications

Despite the rapid development of therapeutic approaches for skin repair, chronic wounds such as diabetic foot ulcers remain an unaddressed problem that affects millions of people worldwide. Increasing evidence has revealed the crucial and diverse roles of the immune cells in the development and repair of the skin tissue, prompting new research to focus on further understanding and modulating the local immune niche for comprehensive, 'perfect' regeneration. In this review, we first introduce how different immunocytes and certain stromal cells involved in innate and adaptive immunity coordinate to maintain the immune niche and tissue homeostasis, with emphasis on their specific roles in normal and pathological wound healing. We then discuss novel engineering approaches - particularly biomaterials systems and cellular therapies - to target different players of the immune niche, with three major aims to i) overcome 'under-healing', ii) avoid 'over-healing', and iii) promote functional restoration, including appendage development. Finally, we highlight how these strategies strive to manage chronic wounds and achieve full structural and functional skin recovery by creating desirable 'soil' through modulating the immune microenvironment.

Impact of Comorbidities on Hospitalization for Injuries in Riders of Electric Bikes and Powered Scooters: A Retrospective Cross-Sectional Study

Background and Objectives: Injuries associated with electric bikes (E-bikes) and powered scooters (P-scooters) have increased yearly worldwide. We aimed to evaluate the impact of pre-existing comorbidities on the probability of hospitalization for injuries in riders of E-bikes and P-scooters. Materials and Methods: A retrospective cross-sectional study design was used. The cohort included patients referred to the emergency department (ED) of a tertiary medical center in 2014–2020 for injuries sustained while riding an E-bike or P-scooter. Data were collected from the medical files on demographics, clinical characteristics including pre-existing comorbidities and permanent use of medications, and injury characteristics. Findings were compared between patients referred for hospitalization from the ED and patients discharged home. Results: Of the 1234 patients who met the inclusion criteria, 202 (16.4%) had a prior medical condition and 167 (13.5%) were taking medication on a permanent basis. A significant relationship was found between hospitalization and having a medical condition (𝜒²(1) = 9.20, p = 0.002) or taking medication on a permanent basis (𝜒²(1) = 6.24, p = 0.01). Hospitalization for injuries was more likely in patients with a comorbidity (27.8%) than those without a comorbidity (15.5%), and in patients who were on permanent drug therapy (22.2%) than in patients who were not (12.9%). Surprisingly, anticoagulant intake specifically had no effect on the probability of hospital admission. Conclusions: Patients with comorbidities have a higher incidence of hospitalization for E-bike- and P-scooter-associated injuries. Therefore, physicians may take into account comorbidities for the effective management of this patient group’s injuries.

Cutaneous Wound Healing: A Review about Innate Immune Response and Current Therapeutic Applications

Skin wounds and compromised wound healing are major concerns for the public. Although skin wound healing has been studied for decades, the molecular and cellular mechanisms behind the process are still not completely clear. The systemic responses to trauma involve the body’s inflammatory and immunomodulatory cellular and humoral networks. Studies over the years provided essential insights into a complex and dynamic immunity during the cutaneous wound healing process. This review will focus on innate cell populations involved in the initial phase of this orchestrated process, including innate cells from both the skin and the immune system.

Ginsenoside Rg3 attenuates skin disorders via down-regulation of MDM2/HIF1α signaling pathway

Background

Thymic stromal lymphopoietin (TSLP) acts as a master switch for inflammatory responses. Ginsenoside Rg3 (Rg3) which is an active ingredient of Panax ginseng Meyer (Araliaceae) is known to possess various therapeutic effects. However, a modulatory effect of Rg3 on TSLP expression in the inflammatory responses remains poorly understood.

Methods

We investigated antiinflammatory effects of Rg3 on an in vitro model using HMC-1 cells stimulated by PMA plus calcium ionophore (PMACI), as well as an in vivo model using PMA-induced mouse ear edema. TSLP and vascular endothelial growth factor (VEGF) levels were detected using enzyme-linked immunosorbent assay or real-time PCR analysis. Murine double minute 2 (MDM2) and hypoxia-inducible factor 1α (HIF1α) expression levels were detected using Western blot analysis.

Results

Rg3 treatment restrained the production and mRNA expression levels of TSLP and VEGF in activated HMC-1 cells. Rg3 down-regulated the MDM2 expression level increased by PMACI stimulation. The HIF1α expression level was also reduced by Rg3 in activated HMC-1 cells. In addition, Rg3-administered mice showed the decreased redness and ear thickness in PMA-irritated ear edema. Rg3 inhibited the TSLP and VEGF levels in the serum and ear tissue homogenate. Moreover, the MDM2 and HIF1α expression levels in the ear tissue homogenate were suppressed by Rg3.

Conclusion

Taken together, the current study identifies new mechanistic evidence about MDM2/HIF1α pathway in the antiinflammatory effect of Rg3, providing a new effective therapeutic strategy for the treatment of skin inflammatory diseases.

The transcriptional characteristics of mast cells derived from skin tissue in type 2 diabetes patients at the single-cell level

OBJECTIVES

The mechanisms underlying the role of mast cells in wound healing have not been thoroughly studied, and even fewer data are available on studies related to mast cells in the skin of patients with type 2 diabetes mellitus (T2DM). Therefore, this study aims to explore the transcriptional characteristics of mast cells at the single-cell level in patients with T2DM and provide experimental data for studying mast cell behaviors under abnormal glucose metabolism.

METHODS

Two patients with T2DM and one trauma patient without diabetes were enrolled. Samples were derived from skin tissue resected at the time of surgery and were isolated by single cell capture technology on BD platform to prepare single cell cDNA library. Seurat was used to process raw reads and analyze data downstream of single-cell RNA sequencing, including removal of low-quality cells, identification of cell clusters at the single-cell level, and screening for differential genes with fold change > 1.5 and p < 0.05 by two-sided t-test. We performed single-cell RNA sequencing on skin tissues of T2DM patients and non-diabetics and identified the cell cluster of skin, single-cell subsets, and transcriptional characteristics of mast cells at a single-cell level. Meanwhile, gene set enrichment(GSEA) analysis was performed on the differentially expressed genes.

RESULTS

A total of 8888 cells were obtained from skin tissue. Clustering analysis revealed eight-cell clusters, identified as smooth muscle cells, dendritic cells, mast cells, and T cells, respectively. Cluster 6 was identified as mast cells with the marker genes TPSAB1, CPA3, TPSB2, MS4A2,KIT, etc., which accounting for 2.7% of the total cell number.Compared with the control group, the genes highly expressed in MCs from T2DM patients, include ADH1C, PAXIP1, HAS1, ARG1, etc., and the low expression genes include PHACTR2, GGA1, RASSF2, etc. GSEA analysis suggested that the signal pathways of MCS in T2DM patients included VEGF signaling pathway, Fc gamma R-mediated phagocytosis, the B cell receptor signaling pathway, natural killer cell-mediated cytotoxicity.

CONCLUSIONS

The characteristic genes of MCs in the skin tissues of T2DM patients were described at the single-cell level. These genes and enriched signaling pathways provide a theoretical basis and data support for further researches on dermatopathy in patients with diabetes mellitus.

Impact of preconditioned diabetic stem cells and photobiomodulation on quantity and degranulation of mast cells in a delayed healing wound simulation in type one diabetic rats

Herein, we report the influence of administering different protocols of preconditioned diabetic adipose-derived mesenchymal stem cells (ADSs) with photobiomodulation in vitro, and photobiomodulation in vivo on the number of mast cells (MCs), their degranulation, and wound strength in the maturation step of a Methicillin-resistant Staphylococcus aureus (MRSA)-infectious wound model in rats with type one diabetes. An MRSA-infectious wound model was generated on diabetic animals, and they were arbitrarily assigned into five groups (G). G1 were control rats. In G2, diabetic ADS were engrafted into the wounds. In G3, diabetic ADS were engrafted into the wound, and the wound was exposed to photobiomodulation (890 nm, 890 ± 10 nm, 80 Hz, 0.2 J/cm²) in vivo. In G4, preconditioned diabetic ADS with photobiomodulation (630 and 810 nm; each 3 times with 1.2 J/cm²) in vitro were engrafted into the wound. In G5, preconditioned diabetic ADS with photobiomodulation were engrafted into the wound, and the wound was exposed to photobiomodulation in vivo. The results showed that, the maximum force in all treatment groups was remarkably greater compared to the control group (all, p = 0.000). Maximum force in G4 and G5 were superior than that other treated groups (both p = 0.000). Moreover, G3, G4, and G5 showed remarkable decreases in completely released MC granules and total numbers of MC compared to G1 and G2 (all, p = 0.000). We concluded that diabetic rats in group 5 showed significantly better results in terms of accelerated wound healing and MC count of an ischemic infected delayed healing wound model.

Mast Cells and the Pancreas in Human Type 1 and Type 2 Diabetes

Mast cells are highly differentiated, widely distributed cells of the innate immune system, that are currently considered as key regulators of both innate and adaptive immunity. Mast cells play a key role in health and survival mechanisms, especially as sentinel cells that can stimulate protective immune responses. On the other hand, it has been shown that mast cells are involved in the pathogenesis of several diseases, and recently a possible pathogenetic role of mast cells in diabetes has been proposed. In this review we summarize the evidence on the increased presence of mast cells in the pancreas of subjects with type 1 diabetes, which is due to the autoimmune destruction of insulin secreting beta cells, and discuss the differences with type 2 diabetes, the other major form of diabetes. In addition, we describe some of the pathophysiological mechanisms through which mast cells might exert their actions, which could be targeted to potentially protect the beta cells in autoimmune diabetes.

The Insights of Microbes' Roles in Wound Healing: A Comprehensive Review

A diverse range of normal flora populates the human skin and numbers are relatively different between individuals and parts of the skin. Humans and normal flora have formed a symbiotic relationship over a period of time. With numerous disease processes, the interaction between the host and normal flora can be interrupted. Unlike normal wound healing, which is complex and crucial to sustaining the skin’s physical barrier, chronic wounds, especially in diabetes, are wounds that fail to heal in a timely manner. The conditions become favorable for microbes to colonize and establish infections within the skin. These include secretions of various kinds of molecules, substances or even trigger the immune system to attack other cells required for wound healing. Additionally, the healing process can be slowed down by prolonging the inflammatory phase and delaying the wound repair process, which causes further destruction to the tissue. Antibiotics and wound dressings become the targeted therapy to treat chronic wounds. Though healing rates are improved, prolonged usage of these treatments could become ineffective or microbes may become resistant to the treatments. Considering all these factors, more studies are needed to comprehensively elucidate the role of human skin normal flora at the cellular and molecular level in a chronic injury. This article will review wound healing physiology and discuss the role of normal flora in the skin and chronic wounds.

Two Sides of the Coin: Mast Cells as a Key Regulator of Allergy and Acute/Chronic Inflammation

It is well known that mast cells (MCs) initiate type I allergic reactions and inflammation in a quick response to the various stimulants, including—but not limited to—allergens, pathogen-associated molecular patterns (PAMPs), and damage-associated molecular patterns (DAMPs). MCs highly express receptors of these ligands and proteases (e.g., tryptase, chymase) and cytokines (TNF), and other granular components (e.g., histamine and serotonin) and aggravate the allergic reaction and inflammation. On the other hand, accumulated evidence has revealed that MCs also possess immune-regulatory functions, suppressing chronic inflammation and allergic reactions on some occasions. IL-2 and IL-10 released from MCs inhibit excessive immune responses. Recently, it has been revealed that allergen immunotherapy modulates the function of MCs from their allergic function to their regulatory function to suppress allergic reactions. This evidence suggests the possibility that manipulation of MCs functions will result in a novel approach to the treatment of various MCs-mediated diseases.

Immunology of Acute and Chronic Wound Healing

Skin wounds greatly affect the global healthcare system, creating a substantial burden on the economy and society. Moreover, the situation is exacerbated by low healing rates, which in fact are overestimated in reports. Cutaneous wounds are generally classified into acute and chronic. The immune response plays an important role during acute wound healing. The activation of immune cells and factors initiate the inflammatory process, facilitate wound cleansing and promote subsequent tissue healing. However, dysregulation of the immune system during the wound healing process leads to persistent inflammation and delayed healing, which ultimately result in chronic wounds. The microenvironment of a chronic wound is characterized by high quantities of pro-inflammatory macrophages, overexpression of inflammatory mediators such as TNF-α and IL-1β, increased activity of matrix metalloproteinases and abundance of reactive oxygen species. Moreover, chronic wounds are frequently complicated by bacterial biofilms, which perpetuate the inflammatory phase. Continuous inflammation and microbial biofilms make it very difficult for the chronic wounds to heal. In this review, we discuss the role of innate and adaptive immunity in the pathogenesis of acute and chronic wounds. Furthermore, we review the latest immunomodulatory therapeutic strategies, including modifying macrophage phenotype, regulating miRNA expression and targeting pro- and anti-inflammatory factors to improve wound healing.

A Review of the Evidence for and against a Role for Mast Cells in Cutaneous Scarring and Fibrosis

Scars are generated in mature skin as a result of the normal repair process, but the replacement of normal tissue with scar tissue can lead to biomechanical and functional deficiencies in the skin as well as psychological and social issues for patients that negatively affect quality of life. Abnormal scars, such as hypertrophic scars and keloids, and cutaneous fibrosis that develops in diseases such as systemic sclerosis and graft-versus-host disease can be even more challenging for patients. There is a large body of literature suggesting that inflammation promotes the deposition of scar tissue by fibroblasts. Mast cells represent one inflammatory cell type in particular that has been implicated in skin scarring and fibrosis. Most published studies in this area support a pro-fibrotic role for mast cells in the skin, as many mast cell-derived mediators stimulate fibroblast activity and studies generally indicate higher numbers of mast cells and/or mast cell activation in scars and fibrotic skin. However, some studies in mast cell-deficient mice have suggested that these cells may not play a critical role in cutaneous scarring/fibrosis. Here, we will review the data for and against mast cells as key regulators of skin fibrosis and discuss scientific gaps in the field.