Epigenetic changes in bone marrow progenitor cells influence the inflammatory phenotype and alter wound healing in type 2 diabetes

Epigenetic regulatory mechanism of macrophage polarization in diabetic wound healing (Review)

Diabetic wounds represent a significant complication of diabetes and present a substantial challenge to global public health. Macrophages are crucial effector cells that play a pivotal role in the pathogenesis of diabetic wounds, through their polarization into distinct functional phenotypes. The field of epigenetics has emerged as a rapidly advancing research area, as this phenomenon has the potential to markedly affect gene expression, cellular differentiation, tissue development and susceptibility to disease. Understanding epigenetic mechanisms is crucial to further exploring disease pathogenesis. A growing body of scientific evidence has highlighted the pivotal role of epigenetics in the regulation of macrophage phenotypes. Various epigenetic mechanisms, such as DNA methylation, histone modification and non‑coding RNAs, are involved in the modulation of macrophage phenotype differentiation in response to the various environmental stimuli present in diabetic wounds. The present review provided an overview of the various changes that take place in macrophage phenotypes and functions within diabetic wounds and discussed the emerging role of epigenetic modifications in terms of regulating macrophage plasticity in diabetic wounds. It is hoped that this synthesis of information will facilitate the elucidation of diabetic wound pathogenesis and the identification of potential therapeutic targets.

Programmed BRD9 Degradation and Hedgehog Signaling Activation via Silk-Based Core-Shell Microneedles Promote Diabetic Wound Healing

Wound healing impairment in diabetes mellitus is associated with an excessive inflammatory response and defective regeneration capability with suppressed Hedgehog (Hh) signaling. The bromodomain protein BRD9, a subunit of the non-canonical BAF chromatin-remodeling complex, is critical for macrophage inflammatory response. However, whether the epigenetic drug BRD9 degrader can attenuate the sustained inflammatory state of wounds in diabetes remains unclear. Without a bona fide immune microenvironment, Hh signaling activation fails to effectively rescue the suppressed proliferative ability of dermal fibroblasts and the vascularization of endothelial cells. Therefore, a silk-based core-shell microneedle (MN) patch is proposed to dynamically modulate the wound immune microenvironment and the regeneration process. Specifically, the BRD9 degrader released from the shell of the MNs mitigated the excessive inflammatory response in the early phase. Subsequently, the positively charged Hh signaling agonist is released from the negatively charged core of the silk fibroin nanofibers and promotes the phase transition from inflammation to regeneration, including re-epithelialization, collagen deposition, and angiogenesis. These findings suggest that the programmed silk-based core-shell MN patch is an ideal therapeutic strategy for effective skin regeneration in diabetic wounds.

Enrichment of H3S28p and H3K9me2 Epigenetic Marks on Inflammatory-Associated Gene Promoters in Response to Severe Burn Injury

BACKGROUND

Severe burns activate systemic inflammation and lead to an increase in cytokine levels. Epigenetic elements are key regulators of inflammation; however, their involvement in severe burns has not been studied. In this work, we aimed to unveil the histone H3 posttranslational modifications (PTM) profile and their enrichment in promoters of inflammatory genes in response to severe burns.

METHODS

The levels of H3 PTMs were analyzed by ELISA assays in circulating cells from burn patients. ChIP assays were conducted to evaluate the enrichment of H3K9me2 and H3S28p at the promoter of CXCL8, IL-17, TNFA, IL-6, FOS, and IL-1B genes.

RESULTS

We found that eight H3 PTMs decreased at 5 days post-burn. Burn patients showed a decreased enrichment of H3K9me2 in CXCL8, IL-17, and TNFA promoters, whereas IL-6, FOS, and IL-1B promoters displayed an H3S28p enrichment diminution during the first 10 days post-burn. Interestingly, burn-injured septic patients exhibited an increased enrichment of H3K9me2 in TNFA, IL-1B, CXCL8, and IL-17 promoters, whereas H3S28p was increased in promoters of TNFA and IL-1B at 1 dpb.

CONCLUSION

Severe burns trigger epigenetic changes and differential H3 PTM enrichment at inflammation gene promoters. Epigenetic misregulation of H3 may be involved in sepsis occurrence after severe burn injury.

ECRG4 mediates host response to cutaneous infection by regulating neutrophil recruitment and adhesion receptor expression

Rapid neutrophil recruitment is critical for controlling infection, with dysfunctional neutrophil responses in diseases like diabetes associated with greater morbidity and mortality. We have shown that the leukocyte protein ECRG4 enhances early neutrophil recruitment to cutaneous wounds and hypothesized that ECRG4 regulates the early host response to infection. Using a cutaneous infection model, we found that ECRG4 KO mice had decreased early neutrophil recruitment with persistent larger lesions, increased bacterial proliferation and systemic dissemination. Although previous work identified ECRG4 as a negative regulator of CD44 on neutrophils, the mechanism regulating neutrophil recruitment remained unknown. We demonstrated that pro-inflammatory responses were intact in ECRG4 KO mice, but found decreased neutrophil mobilization from bone marrow and decreased migration to chemokines. ECRG4 KO mouse neutrophils demonstrated an increase in adhesion molecules that regulate recruitment, including enhanced induction of integrin CD11b and increased L-selectin and CD44 on bone marrow neutrophils. Analysis of gene expression in leukocytes from diabetic patients found decreased ECRG4 expression with similar increased L-selectin and CD44. We propose a previously unrecognized mechanism governing neutrophil recruitment, whereby ECRG4 mediates neutrophil surface adhesion molecules that determine both recruitment and outside-in signaling that modulates neutrophil response to pro-inflammatory stimuli.

The STAT3/SETDB2 axis dictates NF-κB-mediated inflammation in macrophages during wound repair

Macrophage transition from an inflammatory to reparative phenotype after tissue injury is controlled by epigenetic enzymes that regulate inflammatory gene expression. We have previously identified that the histone methyltransferase SETDB2 in macrophages drives tissue repair by repressing NF-κB-mediated inflammation. Complementary ATAC-Seq and RNA-Seq of wound macrophages isolated from mice deficient in SETDB2 in myeloid cells revealed that SETDB2 suppresses the inflammatory gene program by inhibiting chromatin accessibility at NF-κB-dependent gene promoters. We found that STAT3 was required for SETDB2 expression in macrophages, yet paradoxically, it also functioned as a binding partner of SETDB2 where it repressed SETDB2 activity by inhibiting its interaction with the NF-κB component, RELA, leading to increased RELA/NF-κB-mediated inflammatory gene expression. Furthermore, RNA-Seq in wound macrophages from STAT3-deficient mice corroborated this and revealed STAT3 and SETDB2 transcriptionally coregulate overlapping genes. Finally, in diabetic wound macrophages, STAT3 expression and STAT3/SETDB2 binding were increased. We have identified what we believe to be a novel STAT3/SETDB2 axis that modulates macrophage phenotype during tissue repair and may be an important therapeutic target for nonhealing diabetic wounds.

Emerging role of Jumonji domain-containing protein D3 in inflammatory diseases

Jumonji domain-containing protein D3 (JMJD3) is a 2-oxoglutarate-dependent dioxygenase that specifically removes transcriptional repression marks di- and tri-methylated groups from lysine 27 on histone 3 (H3K27me2/3). The erasure of these marks leads to the activation of some associated genes, thereby influencing various biological processes, such as development, differentiation, and immune response. However, comprehensive descriptions regarding the relationship between JMJD3 and inflammation are lacking. Here, we provide a comprehensive overview of JMJD3, including its structure, functions, and involvement in inflammatory pathways. In addition, we summarize the evidence supporting JMJD3's role in several inflammatory diseases, as well as the potential therapeutic applications of JMJD3 inhibitors. Additionally, we also discuss the challenges and opportunities associated with investigating the functions of JMJD3 and developing targeted inhibitors and propose feasible solutions to provide valuable insights into the functional exploration and discovery of potential drugs targeting JMJD3 for inflammatory diseases.

Diabetic Wound Keratinocytes Induce Macrophage JMJD3-Mediated Nlrp3 Expression via IL-1R Signaling

Macrophage (Mφ) plasticity is critical for normal wound repair; however, in type 2 diabetic wounds, Mφs persist in a low-grade inflammatory state that prevents the resolution of wound inflammation. Increased NLRP3 inflammasome activity has been shown in diabetic wound Mφs; however, the molecular mechanisms regulating NLRP3 expression and activity are unclear. Here, we identified that diabetic wound keratinocytes induce Nlrp3 gene expression in wound Mφs through IL-1 receptor-mediated signaling, resulting in enhanced inflammasome activation in the presence of pathogen-associated molecular patterns and damage-associated molecular patterns. We found that IL-1α is increased in human and murine wound diabetic keratinocytes compared with nondiabetic controls and directly induces Mφ Nlrp3 expression through IL-1 receptor signaling. Mechanistically, we report that the histone demethylase, JMJD3, is increased in wound Mφs late post-injury and is induced by IL-1α from diabetic wound keratinocytes, resulting in Nlrp3 transcriptional activation through an H3K27me3-mediated mechanism. Using genetically engineered mice deficient in JMJD3 in myeloid cells (Jmjd3f/flyz2Cre+), we demonstrate that JMJD3 controls Mφ-mediated Nlrp3 expression during diabetic wound healing. Thus, our data suggest a role for keratinocyte-mediated IL-1α/IL-1R signaling in driving enhanced NLRP3 inflammasome activity in wound Mφs. These data also highlight the importance of cell cross-talk in wound tissues and identify JMJD3 and the IL-1R signaling cascade as important upstream therapeutic targets for Mφ NLRP3 inflammasome hyperactivity in nonhealing diabetic wounds.

ARTICLE HIGHLIGHTS

The histone methyltransferase Mixed-lineage-leukemia-1 drives T cell phenotype via Notch signaling in diabetic tissue repair

Immune cell-mediated inflammation is important in normal tissue regeneration but can be pathologic in diabetic wounds. Limited literature exists on the role of CD4+ T cells in normal or diabetic wound repair; however, the imbalance of CD4+ Th17/Tregs has been found to promote inflammation in other diabetic tissues. Here, using human tissue and murine transgenic models, we identified that the histone methyltransferase Mixed-lineage-leukemia-1 (MLL1) directly regulates the Th17 transcription factor RORγ via an H3K4me3 mechanism and increases expression of Notch receptors and downstream Notch signaling. Furthermore, we found that Notch receptor signaling regulates CD4+ Th cell differentiation and is critical for normal wound repair, and loss of upstream Notch pathway mediators or receptors in CD4+ T cells resulted in the loss of CD4+ Th cell differentiation in wounds. In diabetes, MLL1 and Notch-receptor signaling was upregulated in wound CD4+ Th cells, driving CD4+ T cells toward the Th17 cell phenotype. Treatment of diabetic wound CD4+ T cells with a small molecule inhibitor of MLL1 (MI-2) yielded a significant reduction in CD4+ Th17 cells and IL-17A. This is the first study to our knowledge to identify the MLL1-mediated mechanisms responsible for regulating the Th17/Treg balance in normal and diabetic wounds and to define the complex role of Notch signaling in CD4+ T cells in wounds, where increased or decreased Notch signaling both result in pathologic wound repair. Therapeutic targeting of MLL1 in diabetic CD4+ Th cells may decrease pathologic inflammation through regulation of CD4+ T cell differentiation.

Histone modifications and their roles in macrophage-mediated inflammation: a new target for diabetic wound healing

Impaired wound healing is one of the main clinical complications of type 2 diabetes (T2D) and a major cause of lower limb amputation. Diabetic wounds exhibit a sustained inflammatory state, and reducing inflammation is crucial to diabetic wounds management. Macrophages are key regulators in wound healing, and their dysfunction would cause exacerbated inflammation and poor healing in diabetic wounds. Gene regulation caused by histone modifications can affect macrophage phenotype and function during diabetic wound healing. Recent studies have revealed that targeting histone-modifying enzymes in a local, macrophage-specific manner can reduce inflammatory responses and improve diabetic wound healing. This article will review the significance of macrophage phenotype and function in wound healing, as well as illustrate how histone modifications affect macrophage polarization in diabetic wounds. Targeting macrophage phenotype with histone-modifying enzymes may provide novel therapeutic strategies for the treatment of diabetic wound healing.

Macrophage-Centric Biomaterials for Bone Regeneration in Diabetes Mellitus: Contemporary Advancements, Challenges, and Future Trajectories

Increased susceptibility to bone fragility and the diminution of bone regenerative capacity are recognized as significant and frequent sequelae of diabetes mellitus. Research has elucidated the pivotal role of macrophages in the pathogenesis and repair of diabetic bone defects. Notwithstanding this, the therapeutic efficacy of traditional interventions remains predominantly inadequate. Concomitant with substantial advancements in tissue engineering in recent epochs, there has been an escalation in the development of biomaterials designed to modulate macrophage activity, thereby augmenting osseous tissue regeneration in the context of hyperglycemia. This review amalgamates insights from extant research and delineates recent progressions in the domain of biomaterials that target macrophages for the regeneration of diabetic bone, whilst also addressing the clinical challenges and envisaging future directions within this field.

Epigenetic Alteration of Smooth Muscle Cells Regulates Endothelin-Dependent Blood Pressure and Hypertensive Arterial Remodeling

Long-standing hypertension (HTN) affects multiple organ systems and leads to pathologic arterial remodeling, which is driven largely by smooth muscle cell (SMC) plasticity. Although genome wide association studies (GWAS) have identified numerous variants associated with changes in blood pressure in humans, only a small percentage of these variants actually cause HTN. In order to identify relevant genes important in SMC function in HTN, we screened three separate human GWAS and Mendelian randomization studies to identify SNPs located within non-coding gene regions, focusing on genes encoding epigenetic enzymes, as these have been recently identified to control SMC fate in cardiovascular disease. We identified SNPs rs62059712 and rs74480102 in the promoter of the human JMJD3 gene and show that the minor C allele increases JMJD3 transcription in SMCs via increased SP1 binding to the JMJD3 promoter. Using our novel SMC-specific Jmjd3-deficient murine model ( Jmjd3 flox/flox Myh11 CreERT ), we show that loss of Jmjd3 in SMCs results in HTN, mechanistically, due to decreased EDNRB expression and a compensatory increase in EDNRA expression. As a translational corollary, through single cell RNA-sequencing (scRNA-seq) of human arteries, we found strong correlation between JMJD3 and EDNRB expression in SMCs. Further, we identified that JMJD3 is required for SMC-specific gene expression, and loss of JMJD3 in SMCs in the setting of HTN results in increased arterial remodeling by promoting the SMC synthetic phenotype. Our findings link a HTN-associated human DNA variant with regulation of SMC plasticity, revealing therapeutic targets that may be used in the screening and/or personalized treatment of HTN.

Histone demethylase JARID1C/KDM5C regulates Th17 cells by increasing IL-6 expression in diabetic plasmacytoid dendritic cells

Plasmacytoid dendritic cells (pDCs) are first responders to tissue injury, where they prime naive T cells. The role of pDCs in physiologic wound repair has been examined, but little is known about pDCs in diabetic wound tissue and their interactions with naive CD4+ T cells. Diabetic wounds are characterized by increased levels of inflammatory IL-17A cytokine, partly due to increased Th17 CD4+ cells. This increased IL-17A cytokine, in excess, impairs tissue repair. Here, using human tissue and murine wound healing models, we found that diabetic wound pDCs produced excess IL-6 and TGF-β and that these cytokines skewed naive CD4+ T cells toward a Th17 inflammatory phenotype following cutaneous injury. Further, we identified that increased IL-6 cytokine production by diabetic wound pDCs is regulated by a histone demethylase, Jumonji AT-rich interactive domain 1C histone demethylase (JARID1C). Decreased JARID1C increased IL-6 transcription in diabetic pDCs, and this process was regulated upstream by an IFN-I/TYK2/JAK1,3 signaling pathway. When inhibited in nondiabetic wound pDCs, JARID1C skewed naive CD4+ T cells toward a Th17 phenotype and increased IL-17A production. Together, this suggests that diabetic wound pDCs are epigenetically altered to increase IL-6 expression that then affects T cell phenotype. These findings identify a therapeutically manipulable pathway in diabetic wounds.

Relieving Macrophage Dysfunction by Inhibiting SREBP2 Activity: A Hypoxic Mesenchymal Stem Cells-Derived Exosomes Loaded Multifunctional Hydrogel for Accelerated Diabetic Wound Healing

Macrophage dysfunction is one of the primary factors leading to the delayed healing of diabetic wounds. Hypoxic bone marrow mesenchymal stem cells-derived exosomes (hyBMSC-Exos) have been shown to play an active role in regulating cellular function through the carried microRNAs. However, the administration of hyBMSC-Exos alone in diabetic wounds usually brings little effect, because the exosomes are inherently unstable and have a short retention time at the wounds. In this study, a multifunctional hydrogel based on gallic acid (GA) conjugated chitosan (Chi-GA) and partially oxidized hyaluronic acid (OHA) is prepared for sustained release of hyBMSC-Exos. The hydrogel not only exhibits needs-satisfying physicochemical properties, but also displays outstanding biological performances such as low hemolysis rate, strong antibacterial capacity, great antioxidant ability, and excellent biocompatibility. It has the ability to boost the stability of hyBMSC-Exos, leading to a continuous and gradual release of the exosomes at wound locations, ultimately enhancing the exosomes' uptake efficiency by target cells. Most importantly, hyBMSC-Exos loaded hydrogel shows an excellent ability to promote diabetic wound healing by regulating macrophage polarization toward M2 phenotype. This may be because exosomal miR-4645-5p and antioxidant property of the hydrogel synergistically inhibit SREBP2 activity in macrophages. This study presents a productive approach for managing diabetic wounds.

KAT8 beyond Acetylation: A Survey of Its Epigenetic Regulation, Genetic Variability, and Implications for Human Health

Lysine acetyltransferase 8, also known as KAT8, is an enzyme involved in epigenetic regulation, primarily recognized for its ability to modulate histone acetylation. This review presents an overview of KAT8, emphasizing its biological functions, which impact many cellular processes and range from chromatin remodeling to genetic and epigenetic regulation. In many model systems, KAT8's acetylation of histone H4 lysine 16 (H4K16) is critical for chromatin structure modification, which influences gene expression, cell proliferation, differentiation, and apoptosis. Furthermore, this review summarizes the observed genetic variability within the KAT8 gene, underscoring the implications of various single nucleotide polymorphisms (SNPs) that affect its functional efficacy and are linked to diverse phenotypic outcomes, ranging from metabolic traits to neurological disorders. Advanced insights into the structural biology of KAT8 reveal its interaction with multiprotein assemblies, such as the male-specific lethal (MSL) and non-specific lethal (NSL) complexes, which regulate a wide range of transcriptional activities and developmental functions. Additionally, this review focuses on KAT8's roles in cellular homeostasis, stem cell identity, DNA damage repair, and immune response, highlighting its potential as a therapeutic target. The implications of KAT8 in health and disease, as evidenced by recent studies, affirm its importance in cellular physiology and human pathology.

1,25(OH)2D3 improves diabetic wound healing by modulating inflammation and promoting angiogenesis

Vitamin D was found to regulate inflammatory response and angiogenesis, which were often impaired in diabetic wound healing. This study aimed to investigate the effects of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] on diabetic wound healing both in vivo and in vitro. Diabetes was induced by high-fat diet combined with streptozotocin. After four weeks of establishing diabetic mouse model, full-thickness excisional wounds were created on their dorsal skin. Then 1,25(OH)2D3 was administered via intraperitoneal injection for 14 consecutive days. Human umbilical vein endothelial cells (HUVECs) were cultured with normal glucose, high glucose, high glucose plus 1,25(OH)2D3. Cell proliferation, migration, tube formation, and expression levels of relevant pathway components were measured. Intervention with 1,25(OH)2D3 significantly increased wound closure rates of diabetic mice. During the inflammatory phase, 1,25(OH)2D3 alleviated excessive inflammation and promoted the transition of macrophages from M1 to M2 phenotype. Regarding vascular endothelial function, 1,25(OH)2D3 significantly up-regulated eNOS protein expression and inhibited Vcam-1 mRNA expression in diabetic mice (P < 0.05). As for angiogenesis, 1,25(OH)2D3 markedly increased CD31-positive area, the protein and mRNA expression of VEGF, VEGFR2, PDGF, and PDGFRβ, as well as the mRNA expression of Bfgf and Egfr (P < 0.05). In vitro, 1,25(OH)2D3 restored impaired cell proliferation, migration, and tube formation induced by high-glucose, and up-regulated expression of angiogenesis-related factors. These protective effects might be mediated through PI3K/AKT/HIF-1α pathway. These findings suggested that 1,25(OH)2D3 accelerated diabetic wound healing by modulating inflammation, restoring vascular endothelial dysfunction, and promoting angiogenesis.

Persistent epigenetic signals propel a senescence-associated secretory phenotype and trained innate immunity in CD34+ hematopoietic stem cells from diabetic patients

BACKGROUND

Diabetes-induced trained immunity contributes to the development of atherosclerosis and its complications. This study aimed to investigate in humans whether epigenetic signals involved in immune cell activation and inflammation are initiated in hematopoietic stem/progenitor cells (HSPCs) and transferred to differentiated progeny.

METHODS AND RESULTS

High glucose (HG)-exposure of cord blood (CB)-derived HSPCs induced a senescent-associated secretory phenotype (SASP) characterized by cell proliferation lowering, ROS production, telomere shortening, up-regulation of p21 and p27genes, upregulation of NFkB-p65 transcription factor and increased secretion of the inflammatory cytokines TNFα and IL6. Chromatin immunoprecipitation assay (ChIP) of p65 promoter revealed that H3K4me1 histone mark accumulation and methyltransferase SetD7 recruitment, along with the reduction of repressive H3K9me3 histone modification, were involved in NFkB-p65 upregulation of HG-HSPCs, as confirmed by increased RNA polymerase II engagement at gene level. The differentiation of HG-HSPCs into myeloid cells generated highly responsive monocytes, mainly composed of intermediate subsets (CD14hiCD16+), that like the cells from which they derive, were characterized by SASP features and similar epigenetic patterns at the p65 promoter. The clinical relevance of our findings was confirmed in sternal BM-derived HSPCs of T2DM patients. In line with our in vitro model, T2DM HSPCs were characterized by SASP profile and SETD7 upregulation. Additionally, they generated, after myeloid differentiation, senescent monocytes mainly composed of proinflammatory intermediates (CD14hiCD16+) characterized by H3K4me1 accumulation at NFkB-p65 promoter.

CONCLUSIONS

Hyperglycemia induces marked chromatin modifications in HSPCs, which, once transmitted to the cell progeny, contributes to persistent and pathogenic changes in immune cell function and composition.

Cardiac macrophage metabolism in health and disease

Cardiac macrophages are essential mediators of cardiac development, tissue homeostasis, and response to injury. Cell-intrinsic shifts in metabolism and availability of metabolites regulate macrophage function. The human and mouse heart contain a heterogeneous compilation of cardiac macrophages that are derived from at least two distinct lineages. In this review, we detail the unique functional roles and metabolic profiles of tissue-resident and monocyte-derived cardiac macrophages during embryonic development and adult tissue homeostasis and in response to pathologic and physiologic stressors. We discuss the metabolic preferences of each macrophage lineage and how metabolism influences monocyte fate specification. Finally, we highlight the contribution of cardiac macrophages and derived metabolites on cell-cell communication, metabolic health, and disease pathogenesis.

Diet-Induced Obesity Increases Monocyte/Macrophage Proliferation during Skin Wound Healing in Mice

Obesity is associated with low-grade chronic inflammation and impaired glucose metabolism, both of which are detrimental to wound healing. C-C motif chemokine receptor 2 (CCR2) plays an important role in cell recruitment during healing, and our recent studies revealed the significance of CCR2-CCL2 signaling in promoting the proliferation of pro-inflammatory monocytes/macrophages in wounds. Therefore, we sought to determine whether diet-induced obesity increases monocyte/macrophage proliferation and their accumulation in skin wounds. We first confirmed that wound closure was delayed in obese CCR2RFP/+ mice fed with a high-fat diet (HFD) compared to mice fed with a normal diet (ND). Using in vivo imaging and flow cytometry analysis, we found that HFD mice had significantly increased accumulation of CCR2+ monocytes/macrophages, particularly pro-inflammatory CCR2+Ly6C+ cells in wounds compared to their ND counterparts. Importantly, HFD mice exhibited an increased proliferation of wound CCR2+Ly6C+ compared to ND mice. Together, our data suggest that obesity leads to an increased proliferation and accumulation of pro-inflammatory CCR2+Ly6C+ monocytes/macrophages in skin wounds, which may contribute to delayed healing.

Epigenetic integration of signaling from the regenerative environment

Skeletal muscle has an extraordinary capacity to regenerate itself after injury due to the presence of tissue-resident muscle stem cells. While these muscle stem cells are the primary contributor to the regenerated myofibers, the process occurs in a regenerative microenvironment where multiple different cell types act in a coordinated manner to clear the damaged myofibers and restore tissue homeostasis. In this regenerative environment, immune cells play a well-characterized role in initiating repair by establishing an inflammatory state that permits the removal of dead cells and necrotic muscle tissue at the injury site. More recently, it has come to be appreciated that the immune cells also play a crucial role in communicating with the stem cells within the regenerative environment to help coordinate the timing of repair events through the secretion of cytokines, chemokines, and growth factors. Evidence also suggests that stem cells can help modulate the extent of the inflammatory response by signaling to the immune cells, demonstrating a cross-talk between the different cells in the regenerative environment. Here, we review the current knowledge on the innate immune response to sterile muscle injury and provide insight into the epigenetic mechanisms used by the cells in the regenerative niche to integrate the cellular cross-talk required for efficient muscle repair.

Recent advances in the mechanism of hydrogen sulfide in wound healing in diabetes

Wound healing difficulties in diabetes continue to be a clinical challenge, posing a considerable burden to patients and society. Recently, exploration of the mechanism of wound healing and associated treatment options in diabetes has become topical. Of note, the positive role of hydrogen sulfide in promoting wound healing has been demonstrated in recent studies. Hydrogen sulfide is a confirmed gas transmitter in mammals, playing an essential role in pathology and physiology. This review describes the mechanism underlying the role of hydrogen sulfide in the promotion of diabetic wound healing and the potential for hydrogen sulfide supplementation as a therapeutic application.

Targeting IL-12 family cytokines: A potential strategy for type 1 and type 2 diabetes mellitus

Diabetes is a common metabolic disease characterized by an imbalance in blood glucose levels. The pathogenesis of diabetes involves the essential role of cytokines, particularly the IL-12 family cytokines. These cytokines, which have a similar structure, play multiple roles in regulating the immune response. Recent studies have emphasized the importance of IL-12 family cytokines in the development of both type 1 and type 2 diabetes mellitus. As a result, they hold promise as potential therapeutic targets for the treatment of these conditions. This review focuses on the potential of targeting IL-12 family cytokines for diabetes therapy based on their roles in the pathogenesis of both types of diabetes. We have summarized various therapies that target IL-12 family cytokines, including drug therapy, combination therapy, cell therapy, gene therapy, cytokine engineering therapy, and gut microbiota modulation. By analyzing the advantages and disadvantages of these therapies, we have evaluated their feasibility for clinical application and proposed possible solutions to overcome any challenges. In conclusion, targeting IL-12 family cytokines for diabetes therapy provides updated insights into their potential benefits, such as controlling inflammation, preserving islet β cells, reversing the onset of diabetes, and impeding the development of diabetic complications.

Analysis of Bulk Transcriptome Sequencing Data and in vitro Experiments Reveal SIN3A as a Potential Target for Diabetic Foot Ulcer

Background

Diabetic foot ulcers (DFUs) represent a severe complication of diabetes associated with reduced quality of life, lower limb amputations, hospitalizations, increased incidence, and mortality. Importantly, a significant number of pathogenic genes remain unexplored in DFUs.

Methods

A series of bioinformatics analyses were performed on publicly available bulk transcriptome sequencing datasets GSE134431 and GSE80178 to explore the transcriptomic changes in DFUs and select core genes for in vitro functional validation. In a focused examination, the differential expression analysis unveiled distinctions in gene expression patterns between DFUs and non-ulcerated diabetic skin tissues. Enriched functional annotations of differentially expressed genes were explored using the DAVID online tool. Protein-protein interaction analysis was conducted to investigate interactions among differentially expressed genes and select core genes. Knockdown or overexpression of core genes in HaCaT keratinocytes was performed to assess their impact on cell proliferation and migration.

Results

Ten core genes were identified. Cell Counting Kit-8 (CCK-8) and scratch assays demonstrated that downregulation of the core gene SIN3A significantly inhibited the migration and proliferation of HaCaT keratinocytes, while overexpression of SIN3A reversed the high-glucose-induced suppression of HaCaT cell viability and migration.

Conclusion

SIN3A expression is downregulated in DFUs. In vitro, SIN3A promotes the proliferation and migration of HaCaT keratinocytes, suggesting it may be a potential therapeutic target for DFUs.

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.

Elderly and Patients with Large Breast Volume Have an Increased Risk of Seroma Formation after Mastectomy-Results of the SerMa Pilot Study

The collective of the SerMa pilot study included 100 cases of primary breast cancer or Carcinoma in situ who had undergone a mastectomy procedure with or without reconstruction of the breast using an implant or expander at Augsburg University Hospital between 12/2019 and 12/2022. The study aimed to investigate possible causes of seroma formation; reported here are the clinicopathological correlations between seroma formation and tumor biology and surgical procedures. Seroma occurred significantly more often in patients with older age (median patient age in cases with seroma was 73 years vs. 52 years without seroma; p < 0.001). In addition, patients with larger mastectomy specimen were significantly more likely to develop seroma (median ablation weight in cases with seroma 580 g vs. 330 g without seroma; p < 0.001). Other significant parameters for seroma formation were BMI (p = 0.005), grading (p = 0.015) and tumor size (p = 0.036). In addition, with insertion of implant or expander, a seroma occurred significantly less frequently (p < 0.001). In a binary logistic regression, age in particular was confirmed as a significant risk factor. In contrast, tumor biological characteristics, number of lymph nodes removed or affected showed no significant effect on seroma formation. The present study shows the need for patient education about the development of seroma in particular in older patients and patients with large breast volumes within the preoperative surgical clarification. These clinicopathological data support the previously published results hypothesizing that seroma formation is related to autoimmune/inflammatory processes and will be tested on a larger collective in the planned international multicenter SerMa study.

Immunometabolism at the Heart of Cardiovascular Disease

Immune cell function among the myocardium, now more than ever, is appreciated to regulate cardiac function and pathophysiology. This is the case for both innate immunity, which includes neutrophils, monocytes, dendritic cells, and macrophages, as well as adaptive immunity, which includes T cells and B cells. This function is fueled by cell-intrinsic shifts in metabolism, such as glycolysis and oxidative phosphorylation, as well as metabolite availability, which originates from the surrounding extracellular milieu and varies during ischemia and metabolic syndrome. Immune cell crosstalk with cardiac parenchymal cells, such as cardiomyocytes and fibroblasts, is also regulated by complex cellular metabolic circuits. Although our understanding of immunometabolism has advanced rapidly over the past decade, in part through valuable insights made in cultured cells, there remains much to learn about contributions of in vivo immunometabolism and directly within the myocardium. Insight into such fundamental cell and molecular mechanisms holds potential to inform interventions that shift the balance of immunometabolism from maladaptive to cardioprotective and potentially even regenerative. Herein, we review our current working understanding of immunometabolism, specifically in the settings of sterile ischemic cardiac injury or cardiometabolic disease, both of which contribute to the onset of heart failure. We also discuss current gaps in knowledge in this context and therapeutic implications.

Biomaterial-Assisted Macrophage Cell Therapy for Regenerative Medicine

Although most tissue types are capable of some form of self-repair and regeneration, injuries that are larger than a critical threshold or those occurring in the setting of certain diseases can lead to impaired healing and ultimately loss of structure and function. The immune system plays an important role in tissue repair and must be considered in the design of therapies in regenerative medicine. In particular, macrophage cell therapy has emerged as a promising strategy that leverages the reparative roles of these cells. Macrophages are critical for successful tissue repair and accomplish diverse functions throughout all phases of the process by dramatically shifting in phenotypes in response to microenvironmental cues. Depending on their response to various stimuli, they may release growth factors, support angiogenesis, and facilitate extracellular matrix remodeling. However, this ability to rapidly shift phenotype is also problematic for macrophage cell therapy strategies, because adoptively transferred macrophages fail to maintain therapeutic phenotypes following their administration to sites of injury or inflammation. Biomaterials are a potential way to control macrophage phenotype in situ while also enhancing their retention at sites of injury. Cell delivery systems incorporated with appropriately designed immunomodulatory signals have potential to achieve tissue regeneration in intractable injuries where traditional therapies have failed. Here we explorecurrent challenges in macrophage cell therapy, especially retention and phenotype control, how biomaterials may overcome them, and opportunities for next generation strategies. Biomaterials will be an essential tool to advance macrophage cell therapy for widespread clinical applications.

Trained immunity as a potential target for therapeutic immunomodulation in Duchenne muscular dystrophy

Dysregulated inflammation involving innate immune cells, particularly of the monocyte/macrophage lineage, is a key contributor to the pathogenesis of Duchenne muscular dystrophy (DMD). Trained immunity is an evolutionarily ancient protective mechanism against infection, in which epigenetic and metabolic alterations confer non-specific hyperresponsiveness of innate immune cells to various stimuli. Recent work in an animal model of DMD (mdx mice) has shown that macrophages exhibit cardinal features of trained immunity, including the presence of innate immune system "memory". The latter is reflected by epigenetic changes and durable transmissibility of the trained phenotype to healthy non-dystrophic mice by bone marrow transplantation. Mechanistically, it is suggested that a Toll-like receptor (TLR) 4-regulated, memory-like capacity of innate immunity is induced at the level of the bone marrow by factors released from the damaged muscles, leading to exaggerated upregulation of both pro- and anti-inflammatory genes. Here we propose a conceptual framework for the involvement of trained immunity in DMD pathogenesis and its potential to serve as a new therapeutic target.

Proteomics and transcriptomics explore the effect of mixture of herbal extract on diabetic wound healing process

BACKGROUND

The annual incidence of diabetic foot ulcers (DFUs) has been reported to vary from 0.2% to 11% in diabetes-specific clinical settings and less than 0.1% to 8% in community- and population-based cohorts. According to the International Diabetes Foundation, approximately 40 million to 60 million people worldwide are affected by DFUs, and a recent meta-analysis indicates a global prevalence of 6.3% among adults with diabetes, or about 33 million individuals. The cost of diabetes care is significant, amounting to $273 billion in direct and $90 billion in indirect expenses annually, in America. Foot complications in diabetes care excess annual expenditures ranging from 50% to 200% above the baseline cost of diabetes-related care. The cost of advanced-stage ulcers can be more than $50,000 per wound episode, and the direct expenses of major amputation are even higher. DFUs can be treated using various methods, including wound dressings, antibiotics, pressure-off loading, skin substitutes, stem cells, debridement, topical oxygen therapy, gene therapy and growth factors. For severe DFUs patients are at risk of amputation if treatment is not timely or appropriate. Amputating limbs not only causes physical pain to patients, but also brings economic burden due to lost productivity, and decreased employment linked to DFUs. Currently, long-term use of local antibiotics in clinical practice is prone to induce drug resistance, while growth factors do not effectively inhibit bacterial growth and control inflammation in wounds. Stem cell and gene therapies are still in the experimental stage. The method of local debridement combined with negative pressure therapy is expensive. Therefore, we urgently need an affordable, non-surgical method to treat diabetic ulcers. Extracts of bark of Bauhinia purpurea, Paeoniae rubrae, Angelica dahurica (Hoffm.) Benth. & Hook.f. ex Franch. & Sav. (Hoffm.) Benth. & Hook.f. ex Franch. & Sav., Acorus calamus L, and Radix Angelicae biseratae have been used as traditional remedies to treat inflammation-related diseases and cutaneous wounds due to their anti-inflammatory properties and their ability to promote vascular renewal. However, there have been few studies on the mixture of these five herbal extracts on diabetic wound healing.

PURPOSE

This study was designed to assess the healing effect of a mixture of five aforementioned herbal extracts on diabetic ulcer wounds in rats, and to reveal the potential mechanisms behind any potential wound healing using transcriptomics and proteomics.

STUDY DESIGN

We designed the experiment to explore the effects of five herbal extracts on diabetic wound healing process through in vivo experiments and to investigate the underlying mechanisms through proteomics and transcriptomics.

METHODS

We used a mixture of five aforementioned herbal extract to treat rat model of diabetic established by intraperitoneal injection of streptozotocin, and a 2 × 2 cm round full-thickness skin defect was created on the back of the rat. Staphylococcus aureus (1 ml of 1.5 × 10⁹ cfu/ml) was evenly applied to the wound. The wound was then observed for 72 h. The infected ulcer model of diabetic rats was considered to be successfully established if the wound was found to be infected with S. aureus. According to different medications, the rats were divided into three groups, namely mixture of herbal extract (MHE), Kangfuxin solution (KFS) and control (Ctrl). The effects of the medicine on wound healing were observed. HE staining and Masson staining were performed to evaluate the histopathological changes and collagen synthesis. IHC staining was used to assess the neovascularization, and M2 macrophage proliferation was determined by immunofluorescence staining. Proteomic and transcriptomic studies were performed to explore potential mechanism of five herbal extracts to promote wound healing. UHPLC-QE-MS was performed to identify the chemical composition of mixture of herbal extract.

RESULTS

The study show that the mixed herbal extract promotes angiogenesis, proliferation of M2 macrophages, and collagen synthesis. Transcriptomics showed that rno-miR-1298, rno-miR-144-5p, and rno-miR-92a-1-5p are vital miRNAs which also play a significant role in role in regulating wound healing. Proteomics results showed that the following proteins were important in wounds treated with MHE: Rack1, LOC100362366, Cops2, Cops6, Eif4e, Eif3c, Rpl12, Srp54, Rpl13 and Lsm7. Autophagy, PI3-Akt and mTOR signaling pathways were enriched after treatment with MHE compared to other groups.

CONCLUSION

Herein, we have shown that MHE containing extracts of bark of Bauhinia purpurea, P. rubrae, A. dahurica (Hoffm.) Benth. & Hook.f. ex Franch. & Sav., A. calamus L, and R. A. biseratae has significant wound healing effects in the diabetic ulcer wound rat model. These results suggest that local application of MHE in diabetic wounds can accelerate the wound healing process. Moreover, in vivo experiments revealed that the diabetic wound healing process was primarily mediated by angiogenesis and M2 macrophage transition. Therefore, this study may provide a promising and non-surgical therapeutic strategy to accelerate diabetic wound healing, thereby decreasing the number of limb amputations in diabetic patients.

New Approaches in Heart Research: Prevention Instead of Cardiomyoplasty?

Cardiovascular diseases are the leading cause of death in industrialized nations. Due to the high number of patients and expensive treatments, according to the Federal Statistical Office (2017) in Germany, cardiovascular diseases account for around 15% of total health costs. Advanced coronary artery disease is mainly the result of chronic disorders such as high blood pressure, diabetes, and dyslipidemia. In the modern obesogenic environment, many people are at greater risk of being overweight or obese. The hemodynamic load on the heart is influenced by extreme obesity, which often leads to myocardial infarction (MI), cardiac arrhythmias, and heart failure. In addition, obesity leads to a chronic inflammatory state and negatively affects the wound-healing process. It has been known for many years that lifestyle interventions such as exercise, healthy nutrition, and smoking cessation drastically reduce cardiovascular risk and have a preventive effect against disorders in the healing process. However, little is known about the underlying mechanisms, and there is significantly less high-quality evidence compared to pharmacological intervention studies. Due to the immense potential of prevention in heart research, the cardiologic societies are calling for research work to be intensified, from basic understanding to clinical application. The topicality and high relevance of this research area are also evident from the fact that in March 2018, a one-week conference on this topic with contributions from top international scientists took place as part of the renowned "Keystone Symposia" ("New Insights into the Biology of Exercise"). Consistent with the link between obesity, exercise, and cardiovascular disease, this review attempts to draw lessons from stem-cell transplantation and preventive exercise. The application of state-of-the-art techniques for transcriptome analysis has opened new avenues for tailoring targeted interventions to very individual risk factors.

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.

Astragalus polysaccharide ameliorates vascular endothelial dysfunction by stimulating macrophage M2 polarization via potentiating Nrf2/HO-1 signaling pathway

BACKGROUND

Oxidative stress and chronic non-infectious inflammation caused vascular endothelial dysfunction (VED) is a critical and initiating factor in Type 2 diabetes induced vascular complications, while macrophage polarization plays a regulatory role in VED. Astragalus polysaccharide (APS) has been widely used for treating diabetic vascular diseases, but its mechanisms of action have not been fully elucidated.

PURPOSE

This study aimed to investigate the modulatory effects of APS on macrophage polarization and to reveal the potential mechanisms of APS in LPS and HG stimulated macrophages and diabetic model rats.

METHODS

In vitro and in vivo studies were used to explore the mechanism of APS. The macrophage polarization and reactive oxygen species (ROS) release was monitored by flow cytometry and the associated inflammatory factors were detected by ELISA. For oxidative stress regulatory pathway detection, protein expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and Heme oxygenase-1 (HO-1) was measured by Western blotting. The vascular endothelial functions were measured by transwell, tube formation assay, scratch assay, adhesion assay. The thoracic aorta pathological changes were evaluated by Haematoxylin-eosin and immunohistochemistry.

RESULTS

In vitro, APS inhibited the LPS/HG-stimulated THP-1 macrophage differentiated into macrophage M1, coupling with reduction in the ROS production and pro-inflammatory factors (TNF-α, IL-6, IL-12) release. Furthermore, endothelial cells proliferation and apoptosis were ameliorated after APS treatment. Meanwhile, APS-treated THP-1/macrophage occurred a differentiation into M2 polarization and anti-inflammatory factors (IL-4, IL-10, and Arg-1) release via enhancing Nrf2/HO-1 signaling pathway, which could be disturbed by using siNrf2. APS promoted the migration and angiogenesis of endothelial cells in co-cultured of HUVECs and macrophages under high glucose. Finally, similar results were observed in vivo, APS alleviated thoracic aorta complications of diabetic rats accompanied by a remarkable reduction in inflammation and an increased in the number of anti-inflammatory macrophage polarization.

CONCLUSION

Our results demonstrated that APS ameliorated vascular endothelial dysfunction in diabetes by stimulating macrophage polarization to M2 via enhancing the Nrf2/HO-1 pathway.

CD300a Regulates Mouse Macrophage Functionality in Allergic Inflammation

BACKGROUND

CD300a is an inhibitory receptor (IR) expressed on several leukocytes, including mast cells (MCs) and macrophages (MΦ), important cells in allergic inflammation (AI). We have previously characterized CD300a role on MCs and in vivo in mouse models of allergy, in which the absence of CD300a resulted in increased inflammatory features and delayed resolution. However, the exact mechanism of this delayed resolution is unclear. Our hypothesis is that MΦ, important players in resolution, might be impaired when CD300a is absent.

OBJECTIVES

The aim of the study was to investigate CD300a-dependent functionality of mouse MΦ.

METHOD

MΦ were purified from the peritoneum of wild-type (WT) and CD300a-/- mice naïve and 48 h and 96 h after challenge with ovalbumin/alum. Phenotype switching was analyzed via specific M1-M2 inducers and markers. MΦ phagocytotic ability was assessed via Staphylococcus aureus pHrodo-conjugated bioparticles. The influence of MCs on MΦ was investigated by incubating WT MΦ with supernatants from non-activated and IgE-activated bone marrow-derived MCs (BMMCs) and analyzing functional responses.

RESULTS

Naïve CD300a-/- MΦ presented with increased sensitivity to activation when treated with LPS. Absence of CD300a results in increased Arg1 expression and increased IL-6 release when MΦ are purified from allergic peritonitis-induced mice. Similar results were obtained when CD300a-/- MΦ were purified 96 h after challenge. On the other hand, CD300a absence did not affect phagocytosis. WT MΦ incubated with supernatants of non-activated and IgE-activated BMMCs presented with increased iNOS expression and decreased Arg1 levels.

CONCLUSIONS

The IR CD300a controls the activation state of MΦ, and its absence could augment the inflammatory state seen in CD300a-/- mice. Moreover, MCs can also influence MΦ phenotype switching. This may partially explain the delayed AI resolution seen in these mice.

The Long Telling Story of "Endothelial Progenitor Cells": Where Are We at Now?

Endothelial progenitor cells (EPCs): The name embodies years of research and clinical expectations, but where are we now? Do these cells really represent the El Dorado of regenerative medicine? Here, past and recent literature about this eclectic, still unknown and therefore fascinating cell population will be discussed. This review will take the reader through a temporal journey that, from the first discovery, will pass through years of research devoted to attempts at their definition and understanding their biology in health and disease, ending with the most recent evidence about their pathobiological role in cardiovascular disease and their recent applications in regenerative medicine.

Puerarin improves diabetic wound healing via regulation of macrophage M2 polarization phenotype

Background

Skin wound healing depends on the progress of different but overlapping stages of healing, including hemostasis, inflammatory, proliferative and remodeling. Failure of these stages to occur in a timely and gradual manner may result in non-healing pathological wounds. Macrophages and neutrophils have been shown to play an essential role in the inflammatory responses of wound tissue, and their active plasticity allows them to modulate tissue damage and repair functions. The ability of macrophages and neutrophils to regulate the occurrence and resolution of inflammatory processes is essential for the treatment of pathological wound healing.

Methods

Mice were categorized into negative control, streptozotocin, streptozotocin + puerarin and puerarin groups. The traditional Chinese medicine extract puerarin was selected to treat different groups of mice with a full-thickness skin defect wound. Cells of the RAW264.7 cell line were stimulated under different puerarin conditions. Then, real time quantitative polymerase chain reaction (RT-qPCR), western blot, immunofluorescence and other assays were carried out to explore the effect of puerarin on wound healing and its molecular mechanism.

Results

Animal experiments found that the wound healing of diabetic mice treated with puerarin was significantly accelerated, and histological analysis found that puerarin treatment markedly decreased the infiltration of macrophages and neutrophils in wound tissue. Through western blot, RT-qPCR and immunofluorescence experiments, it was observed that puerarin treatment remarkably inhibited nuclear factor kinase B (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathways, downregulated the expression of inflammatory cytokines and induced the M2 polarization of macrophages. At the cellular level, we also observed that puerarin improved M2 macrophage polarization and inhibited inflammatory pathway activation in a high-glucose culture.

Conclusion

Puerarin has a significant therapeutic effect on wound healing in diabetic mice. The therapeutic effect is achieved by regulating macrophage polarization through suppressing NF-κB and MAPK signaling cascades.

Hematopoietic Stem Cells in Wound Healing Response

Significance: Emerging evidence has shown a link between the status of hematopoietic stem cells (HSCs) and wound healing responses. Thus, better understanding HSCs will contribute to further advances in wound healing research. Recent Advances: Myeloid cells such as neutrophils and monocyte-derived macrophages are critical players in the process of wound healing. HSCs actively respond to wound injury and other tissue insults, including infection and produce the effector myeloid cells, and a failing of the HSC response can result in impaired wound healing. Technological advances such as transcriptome at single-cell resolution, epigenetics, three-dimensional imaging, transgenic animals, and animal models, have provided novel concepts of myeloid generation (myelopoiesis) from HSCs, and have revealed cell-intrinsic and -extrinsic mechanisms that can impact HSC functions in the context of health conditions. Critical Issues: The newer concepts include-the programmed cellular fate at a differentiation stage that is used to be considered as the multilineage, the signaling pathways that can activate HSCs directly and indirectly, the mechanisms that can deteriorate HSCs, the roles and remodeling of the surrounding environment for HSCs and their progenitors (the niche). Future Directions: The researches on HSCs, which produce blood cells, should contribute to the development of blood biomarkers predicting a risk of chronic wounds, which may transform clinical practice of wound care with precision medicine for patients at high risk of poor healing.

Macrophage-specific inhibition of the histone demethylase JMJD3 decreases STING and pathologic inflammation in diabetic wound repair

Macrophage plasticity is critical for normal tissue repair following injury. In pathologic states such as diabetes, macrophage plasticity is impaired, and macrophages remain in a persistent proinflammatory state; however, the reasons for this are unknown. Here, using single-cell RNA sequencing of human diabetic wounds, we identified increased JMJD3 in diabetic wound macrophages, resulting in increased inflammatory gene expression. Mechanistically, we report that in wound healing, JMJD3 directs early macrophage-mediated inflammation via JAK1,3/STAT3 signaling. However, in the diabetic state, we found that IL-6, a cytokine increased in diabetic wound tissue at later time points post-injury, regulates JMJD3 expression in diabetic wound macrophages via the JAK1,3/STAT3 pathway and that this late increase in JMJD3 induces NFκB-mediated inflammatory gene transcription in wound macrophages via an H3K27me3 mechanism. Interestingly, RNA sequencing of wound macrophages isolated from mice with JMJD3-deficient myeloid cells (Jmjd3f/fLyz2Cre+) identified that the STING gene (Tmem173) is regulated by JMJD3 in wound macrophages. STING limits inflammatory cytokine production by wound macrophages during healing. However, in diabetic mice, its role changes to limit wound repair and enhance inflammation. This finding is important since STING is associated with chronic inflammation, and we found STING to be elevated in human and murine diabetic wound macrophages at late time points. Finally, we demonstrate that macrophage-specific, nanoparticle inhibition of JMJD3 in diabetic wounds significantly improves diabetic wound repair by decreasing inflammatory cytokines and STING. Taken together, this work highlights the central role of JMJD3 in tissue repair and identifies cell-specific targeting as a viable therapeutic strategy for nonhealing diabetic wounds.

Macrophage-Mediated Inflammation in Skin Wound Healing

Macrophages are key immune cells that respond to infections, and modulate pathophysiological conditions such as wound healing. By possessing phagocytic activities and through the secretion of cytokines and growth factors, macrophages are pivotal orchestrators of inflammation, fibrosis, and wound repair. Macrophages orchestrate the process of wound healing through the transitioning from predominantly pro-inflammatory (M1-like phenotypes), which present early post-injury, to anti-inflammatory (M2-like phenotypes), which appear later to modulate skin repair and wound closure. In this review, different cellular and molecular aspects of macrophage-mediated skin wound healing are discussed, alongside important aspects such as macrophage subtypes, metabolism, plasticity, and epigenetics. We also highlight previous studies demonstrating interactions between macrophages and these factors for optimal wound healing. Understanding and harnessing the activity and capability of macrophages may help to advance new approaches for improving healing of the skin.

Evolving spectrum of diabetic wound: Mechanistic insights and therapeutic targets

Diabetes mellitus is a chronic metabolic disorder resulting in an increased blood glucose level and prolonged hyperglycemia, causes long term health conse-quences. Chronic wound is frequently occurring in diabetes patients due to compromised wound healing capability. Management of wounds in diabetic patients remains a clinical challenge despite many advancements in the field of science and technology. Increasing evidence indicates that alteration of the biochemical milieu resulting from alteration in inflammatory cytokines and matrix metalloproteinase, decrease in fibroblast and keratinocyte functioning, neuropathy, altered leukocyte functioning, infection, etc., plays a significant role in impaired wound healing in diabetic people. Apart from the current pharmacotherapy, different other approaches like the use of conventional drugs, antidiabetic medication, antibiotics, debridement, offloading, platelet-rich plasma, growth factor, oxygen therapy, negative pressure wound therapy, low-level laser, extracorporeal shock wave bioengineered substitute can be considered in the management of diabetic wounds. Drugs/therapeutic strategy that induce angiogenesis and collagen synthesis, inhibition of MMPs, reduction of oxidative stress, controlling hyperglycemia, increase growth factors, regulate inflammatory cytokines, cause NO induction, induce fibroblast and keratinocyte proliferation, control microbial infections are considered important in controlling diabetic wound. Further, medicinal plants and/or phytoconstituents also offer a viable alternative in the treatment of diabetic wound. The focus of the present review is to highlight the molecular and cellular mechanisms, and discuss the drug targets and treatment strategies involved in the diabetic wound.

Landscape of the epigenetic regulation in wound healing

Wound healing after skin injury is a dynamic and highly coordinated process involving a well-orchestrated series of phases, including hemostasis, inflammation, proliferation, and tissue remodeling. Epigenetic regulation refers to genome-wide molecular events, including DNA methylation, histone modification, and non-coding RNA regulation, represented by microRNA (miRNA), long noncoding RNA (lncRNA), and circular RNA (circRNA). Epigenetic regulation is pervasively occurred in the genome and emerges as a new role in gene expression at the post-transcriptional level. Currently, it is well-recognized that epigenetic factors are determinants in regulating gene expression patterns, and may provide evolutionary mechanisms that influence the wound microenvironments and the entire healing course. Therefore, this review aims to comprehensively summarize the emerging roles and mechanisms of epigenetic remodeling in wound healing. Moreover, we also pose the challenges and future perspectives related to epigenetic modifications in wound healing, which would bring novel insights to accelerated wound healing.

Differences in H3K4me3 and chromatin accessibility contribute to altered T-cell receptor signaling in neonatal naïve CD4 T cells

Neonatal CD4+ T cells have reduced or delayed T-cell receptor (TCR) signaling responses compared with adult cells, but the mechanisms underlying this are poorly understood. This study tested the hypothesis that human neonatal naïve CD4+ TCR signaling and activation deficits are related to differences in H3K4me3 patterning and chromatin accessibility. Following initiation of TCR signaling using anti-CD3/anti-CD28 beads, adult naïve CD4+ T cells demonstrated increased CD69, phospho-CD3ε and interleukin (IL)-2, tumor necrosis factor-α (TNF-α), interferon-γ and IL-17A compared with neonatal cells. By contrast, following TCR-independent activation using phorbol myristate acetate (PMA)/ionomycin, neonatal cells demonstrated increased expression of CD69, IL-2 and TNF-α and equivalent phospho-ERK compared with adult cells. H3K4me3 chromatin immunoprecipitation-sequencing (ChIP-seq) and assay for transposase-accessible chromatin with high-throughput sequencing (ATAC-seq) were performed on separate cohorts of naïve CD4+ T cells from term neonates and adults, and RNA-seq data from neonatal and adult naïve CD4+ T cells were obtained from the Blueprint Consortium. Adult cells demonstrated overall increased chromatin accessibility and a higher proportion of H3K4me3 sites associated with open chromatin and active gene transcription compared with neonatal cells. Adult cells demonstrated increased mRNA expression of the TCR-associated genes FYN, ITK, CD4, LCK and LAT, which was associated with increased H3K4me3 at the FYN and ITK gene loci and increased chromatin accessibility at the CD4, LCK and LAT loci. These findings indicate that neonatal TCR-dependent defects in activation are epigenetically regulated and provide a potentially targetable mechanism to enhance neonatal CD4+ T-cell responses.

Effect of diabetes on efferocytosis process

Diabetes is a complex of genetic, metabolic, and autoimmune disorders that are characterized by hyperglycemia. Elevated apoptotic cell count following defective clearance of dead cells that can cause chronic inflammation is a hallmark of the diabetic wound. Effective dead cell clearance is a prerequisite for rapid inflammation resolution and successful recovery. Efferocytosis is a multistep process in which phagocytes engulf the dead cells. Cell body elimination is of great significance in disease and homeostasis. Recent research has clarified that diabetic wounds have an enhanced load of the apoptotic cell, which is partly attributed to the dysfunction of macrophages in apoptotic clearance at the site of the diabetic wounds. In the current work, we highlight the pathways implicated in efferocytosis, from the diagnosis of apoptotic cells to the phagocytic swallowing and the homeostatic resolution, and explain the possible pathophysiological episodes occurring when the proceeding is abrogated. Also, we describe the last development in the management of inflammation in diabetes wound and future directions of surveillance.

Epigenetic Reprogramming of the Inflammatory Response in Obesity and Type 2 Diabetes

For the past several decades, the prevalence of obesity and type 2 diabetes (T2D) has continued to rise on a global level. The risk contributing to this pandemic implicates both genetic and environmental factors, which are functionally integrated by epigenetic mechanisms. While these conditions are accompanied by major abnormalities in fuel metabolism, evidence indicates that altered immune cell functions also play an important role in shaping of obesity and T2D phenotypes. Interestingly, these events have been shown to be determined by epigenetic mechanisms. Consistently, recent epigenome-wide association studies have demonstrated that immune cells from obese and T2D individuals feature specific epigenetic profiles when compared to those from healthy subjects. In this work, we have reviewed recent literature reporting epigenetic changes affecting the immune cell phenotype and function in obesity and T2D. We will further discuss therapeutic strategies targeting epigenetic marks for treating obesity and T2D-associated inflammation.

Innovative Cell and Platelet Rich Plasma Therapies for Diabetic Foot Ulcer Treatment: The Allogeneic Approach

Cutaneous chronic wounds are a major global health burden in continuous growth, because of population aging and the higher incidence of chronic diseases, such as diabetes. Different treatments have been proposed: biological, surgical, and physical. However, most of these treatments are palliative and none of them can be considered fully satisfactory. During a spontaneous wound healing, endogenous regeneration mechanisms and resident cell activity are triggered by the released platelet content. Activated stem and progenitor cells are key factors for ulcer healing, and they can be either recruited to the wound site from the tissue itself (resident cells) or from elsewhere. Transplant of skin substitutes, and of stem cells derived from tissues such as bone marrow or adipose tissue, together with platelet-rich plasma (PRP) treatments have been proposed as therapeutic options, and they represent the today most promising tools to promote ulcer healing in diabetes. Although stem cells can directly participate to skin repair, they primarily contribute to the tissue remodeling by releasing biomolecules and microvesicles able to stimulate the endogenous regeneration mechanisms. Stem cells and PRP can be obtained from patients as autologous preparations. However, in the diabetic condition, poor cell number, reduced cell activity or impaired PRP efficacy may limit their use. Administration of allogeneic preparations from healthy and/or younger donors is regarded with increasing interest to overcome such limitation. This review summarizes the results obtained when these innovative treatments were adopted in preclinical animal models of diabetes and in diabetic patients, with a focus on allogeneic preparations.

Characterization of vaginal immune response to a polypropylene mesh: Diabetic vs. normoglycemic conditions

OBJECTIVE

Urogynecology meshes, typically manufactured from polypropylene, are widely used in the surgical treatment of stress urinary incontinence and pelvic organ prolapse. However, mesh-associated complications such as mesh exposure can develop in women undergoing mesh implantation, for which diabetes is an independent risk factor. We aimed to define the impact of diabetes on the vaginal immune response to mesh by comparing diabetic vs. normoglycemic conditions longitudinally in a rat sacrocolpopexy model.

METHODS

Diabetes (blood glucose ≥ 300 mg/dL) was induced in middle-aged female Wistar rats with streptozotocin (STZ). A polypropylene mesh was implanted on the vagina via modified sacrocolpopexy following bilateral ovariectomy and supracervical hysterectomy for 3-, 7-, and 42-days. Sham-operated controls underwent the same procedures without mesh. Mesh-associated inflammation, immune cell populations and cytokine/chemokine profiles were examined in the excised vaginal tissues.

RESULTS

Diabetes was reliably induced starting on the 3rd day following STZ injection. Under both normoglycemic and diabetic conditions, mesh caused a prolonged inflammatory response in the vagina with increased proinflammatory chemokines MCP-1 and MIP-1α as compared to Sham. Major differences between the two conditions were found at the later stage (42 days post-surgery), including an increased inflammation with larger foreign body granuloma and more giant cells at the mesh-tissue interface, increased fraction of macrophages in the immune cell population, and higher proinflammatory chemokine IP-10 in the diabetic group.

CONCLUSION

Polypropylene mesh implanted on the vagina induces prolonged inflammation at the mesh-tissue interface. Diabetes increases the mesh-associated inflammation in the long term, which is related to a dysregulated macrophage response.

STATEMENT OF SIGNIFICANCE

This study investigated the mechanism underlying the increased risk in women with diabetes for developing mesh complications such as mesh exposure. The significance includes: (1) it is the first study investigating vaginal host response to a prosthesis under the influence of diabetes; (2) the longitudinal study design elucidated the dynamic changes of vaginal immune response to mesh from very early to late stages; (3) our findings may inform future mechanistic studies and studies investigating preventive/therapeutic strategies to improve the outcomes of women with diabetes receiving vaginal implants.

Emerging Roles of Sodium Glucose Cotransporter 2 (SGLT-2) Inhibitors in Diabetic Cardiovascular Diseases: Focusing on Immunity, Inflammation and Metabolism

Diabetes mellitus (DM) is one of the most fast evolving global issues characterized by hyperglycemia. Patients with diabetes are considered to face with higher risks of adverse cardiovascular events. Those are the main cause of mortality and disability in diabetes patients. There are novel antidiabetic agents that selectively suppress sodium-glucose cotransporter-2 (SGLT-2). They work by reducing proximal tubule glucose reabsorption. Although increasing evidence has shown that SGLT-2 inhibitors can contribute to a series of cardiovascular benefits in diabetic patients, including a reduced incidence of major adverse cardiovascular events and protection of extracardiac organs, the potential mechanisms of SGLT2 inhibitors’ cardiovascular protective effects are still not fully elucidated. Given the important role of inflammation and metabolism in diabetic cardiovascular diseases, this review is intended to rationally compile the multifactorial mechanisms of SGLT-2 inhibitors from the point of immunity, inflammation and metabolism, depicting the fundamental cellular and molecular processing of SGLT-2 inhibitors exerting regulating immunity, inflammation and metabolism. Finally, future directions and perspectives to prevent or delay cardiovascular complications in DM by SGLT-2 inhibitors are presented.

Inflammatory monocytes infiltrate the spiral ligament and migrate to the basilar membrane after noise exposure

Objectives

Noise exposure leads to an increase in the macrophage population. This increment is thought to be caused by the transformation of infiltrated monocytes into macrophages rather than by proliferation of the cochlear resident macrophages. However, studies on infiltrated monocytes in the cochlea are scarce. Thus, we aimed to investigate the infiltration of monocytes and their transformation into macrophages after noise exposure.

Methods

In wild-type and CX3CR1^+/GFP C57/B6 mice, inflammatory monocytes were identified by immunofluorescence of mouse cochlear cells. The findings were confirmed and quantitated by flow cytometry.

Results

One day after noise exposure, monocytes were identified in the spiral ligament. Flow cytometric analysis confirmed that the monocyte population peaked on post-noise exposure day 1 and decreased thereafter. On day 3 after noise exposure, amoeboid-type macrophages increased in the crista basilaris, and on day 5, they spread to the basilar membrane.

Conclusion

Infiltrated monocytes were successfully observed 1 day after noise exposure, preceding the increase in the macrophage population. This finding supports the proposal that infiltrated monocytes transform into macrophages.

Hematopoietic Progenitors and the Bone Marrow Niche Shape the Inflammatory Response and Contribute to Chronic Disease

It is now well understood that the bone marrow (BM) compartment can sense systemic inflammatory signals and adapt through increased proliferation and lineage skewing. These coordinated and dynamic alterations in responding hematopoietic stem and progenitor cells (HSPCs), as well as in cells of the bone marrow niche, are increasingly viewed as key contributors to the inflammatory response. Growth factors, cytokines, metabolites, microbial products, and other signals can cause dysregulation across the entire hematopoietic hierarchy, leading to lineage-skewing and even long-term functional adaptations in bone marrow progenitor cells. These alterations may play a central role in the chronicity of disease as well as the links between many common chronic disorders. The possible existence of a form of “memory” in bone marrow progenitor cells is thought to contribute to innate immune responses via the generation of trained immunity (also called innate immune memory). These findings highlight how hematopoietic progenitors dynamically adapt to meet the demand for innate immune cells and how this adaptive response may be beneficial or detrimental depending on the context. In this review, we will discuss the role of bone marrow progenitor cells and their microenvironment in shaping the scope and scale of the immune response in health and disease.

Epigenetics: key to improve delayed wound healing in type 2 diabetes

Diabetes-related delayed wound healing is a multifactorial, nuanced, and intertwined complication that causes substantial clinical morbidity. The etiology of diabetes and its related microvascular complications is affected by genes, diet, and lifestyle factors. Epigenetic modifications such as DNA methylation, histone modifications, and post-transcriptional RNA regulation (microRNAs) are subsequently recognized as key facilitators of the complicated interaction between genes and the environment. Current research suggests that diabetes-persuaded dysfunction of epigenetic pathways, which results in changed expression of genes in target cells and cause diabetes-related complications including cardiomyopathy, nephropathy, retinopathy, delayed wound healing, etc., which are foremost drivers to diabetes-related adverse outcomes. In this paper, we discuss the role of epigenetic mechanisms in controlling tissue repair, angiogenesis, and expression of growth factors, as well as recent findings that show the alteration of epigenetic events during diabetic wound healing.