Diabetes impairs wound healing by Dnmt1-dependent dysregulation of hematopoietic stem cells differentiation towards macrophages

SIRT6 Promotes Osteogenic Differentiation of Adipose-Derived Mesenchymal Stem Cells Through Antagonizing DNMT1

Background

Adipose-derived stem cells (ADSCs) are increasingly used in regenerative medicine because of their potential to differentiate into multiple cell types, including osteogenic lineages. Sirtuin protein 6 (SIRT6) is a nicotinamide adenine dinucleotide (NAD)-dependent deacetylase that plays important roles in cell differentiation. NOTCH signaling has also been reported to involve in osteogenic differentiation. However, the function of SIRT6 in osteogenic differentiation of ADSCs and its relation to the NOTCH signaling pathways are yet to be explored.

Methods

The in vitro study with human ADSCs (hADSCs) and in vivo experiments with nude mice have been performed. Alkaline phosphatase (ALP) assays and ALP staining were used to detect osteogenic activity. Alizarin Red staining was performed to detect calcium deposition induced by osteogenic differentiation of ADSCs. Western blot, RT-qPCR, luciferase reporter assay, and co-immunoprecipitation assay were applied to explore the relationship between of SIRT6, DNA methyltransferases (DNMTs) and NOTCHs.

Results

SIRT6 promoted ALP activity, enhanced mineralization and upregulated expression of osteogenic-related genes of hADSCs in vitro and in vivo. Further mechanistic studies showed that SIRT6 deacetylated DNMT1, leading to its unstability at protein level. The decreased expression of DNMT1 prevented the abnormal DNA methylation of NOTCH1 and NOTCH2, resulting in the upregulation of their transcription. SIRT6 overexpression partially suppressed the abnormal DNA methylation of NOTCH1 and NOTCH2 by antagonizing DNMT1, leading to an increased capacity of ADSCs for their osteogenic differentiation.

Conclusion

This study demonstrates that SIRT6 physical interacts with the DNMT1 protein, deacetylating and destabilizing DNMT1 protein, leading to the activation of NOTCH1 and NOTCH2, Which in turn promotes the osteogenic differentiation of ADSCs.

Macrophage Related Chronic Inflammation in Non-Healing Wounds

Persistent hyper-inflammation is a distinguishing pathophysiological characteristic of chronic wounds, and macrophage malfunction is considered as a major contributor thereof. In this review, we describe the origin and heterogeneity of macrophages during wound healing, and compare macrophage function in healing and non-healing wounds. We consider extrinsic and intrinsic factors driving wound macrophage dysregulation, and review systemic and topical therapeutic approaches for the restoration of macrophage response. Multidimensional analysis is highlighted through the integration of various high-throughput technologies, used to assess the diversity and activation states as well as cellular communication of macrophages in healing and non-healing wound. This research fills the gaps in current literature and provides the promising therapeutic interventions for chronic wounds.

3,3'-Diindolylmethane Enhances Paclitaxel Sensitivity by Suppressing DNMT1-Mediated KLF4 Methylation in Breast Cancer

Paclitaxel (PTX) is a first-line chemotherapeutic drug for the treatment of breast cancer, but drug resistance seriously limits its clinical use. The aim of the present work was to explore the effect of 3,3’-diindolylmethane (DIM) on PTX sensitivity and its possible mechanism in breast cancer. The expression of Krüppel-like factor 4 (KLF4) and DNA-methyltransferase 1 (DNMT1) in breast cancer tissues were assessed by immunohistochemistry and Western blotting. The methylation of KLF4 was evaluated by the MassARRAY platform. The lentivirus carrying KLF4 and DNMT1 gene or shRNA targeting DNMT1 were used to overexpress KLF4 or knockdown DNMT1 in MCF-7 and T47D breast cancer cells and the role of KLF4 and DNMT1 in regulation of PTX sensitivity was investigated. The effect of PTX on inhibiting the proliferation of MCF-7 and T47D cells was measured by CCK-8 assay. Flow cytometry was used to examine cell apoptosis. The expression of mRNA and protein was evaluated by qRT-PCR and Western blotting analysis, respectively. Our data showed that the expression of DNMT1 was increased, and the methylation level of CpG sites (−148 bp) in the KLF4 promoter was increased while the KLF4 expression was significantly decreased in breast cancer tissues. Overexpression of KLF4 increased the sensitivity of MCF-7 and T47D cells to PTX. DNMT1 increased the methylation of the KLF4 promoter and decrease the expression of KLF4. Knockdown of DNMT1 increased the sensitivity of MCF-7 and T47D cells to PTX. DIM enhanced the PTX sensitivity of MCF-7 and T47D cells, decreased the expression of DNMT1 and the methylation level of KLF4 promoter, thus increasing the level of KLF4. Furthermore, overexpression of DNMT1 attenuated the effect of DIM on the regulation of PTX sensitivity. Collectively, our data indicated that DNMT1-mediated hypermethylation of KLF4 promoter leads to downregulation of KLF4 in breast cancer. The level of KLF4 is correlated with the sensitivity of MCF-7 and T47D cells to PTX. DIM could enhance the antitumor efficacy of PTX on MCF-7 and T47D cells by regulating DNMT1 and KLF4.

Reduced apoptosis of monocytes and macrophages is associated with their persistence in wounds of diabetic mice

Monocytes and macrophages (Mo/MΦ) rapidly accumulate in skin wounds after injury, then disappear as healing progresses. However, the mechanisms underlying their ultimate fate in wounds remain to be elucidated. Here, we show that apoptosis of Mo/MΦ parallels their reduction as wound healing progresses in non-diabetic mice. scRNAseq analysis confirmed enriched apoptosis GO pathways on day 6 post-injury in wound Mo/MΦ from non-diabetic mice. In contrast, there was significantly less Mo/MΦ apoptosis in wounds from diabetic mice, particularly in the pro-inflammatory Ly6C+ population, which may contribute to persistent Mo/MΦ accumulation and chronic inflammation. scRNAseq analysis implicated TNF, MAPK, Jak-STAT, and FoxO signaling pathways in promoting wound Mo/MΦ apoptosis in non-diabetic mice while cell proliferation related pathways appeared to be activated in diabetic mice. These novel findings indicate that reduced apoptosis is a contributor to persistent Mo/MΦ accumulation in diabetic wounds. These findings also highlight pathways that may regulate Mo/MΦ apoptosis during wound healing, which could be targeted to help resolve inflammation and improve healing.

In Patients with Lower Extremity Burns and Osteomyelitis, Diabetes Mellitus Increases Amputation Rate

In this retrospective analysis, we investigated the rate of radiologically confirmed osteomyelitis, extremity amputation and healthcare utilization in both the diabetic and non-diabetic lower extremity burn populations to determine the impact of diabetes mellitus on these outcomes. The burn registry was used to identify all patients admitted to our tertiary burn center from 2014 to 2018. Only patients with lower extremity burns (foot and/or ankle) were included. Statistical analysis was performed using Student's t test, chi-squared test, and Fischer's exact test. Of the 315 patients identified, 103 had a known diagnosis of diabetes mellitus and 212 did not. Seventeen patients were found to have osteomyelitis within three months of the burn injury. Fifteen of these patients had a history of diabetes. Notably, when non-diabetics were diagnosed with osteomyelitis, significant differences were observed in both length of stay and cost in comparison to their counterparts without osteomyelitis (36 vs 9 days; p=0.0003; $226,289 vs $48,818, p=0.0001). Eleven patients required an amputation and 10 (90.9%) of these patients had comorbid diabetes and documented diabetic neuropathy. Compared to non-diabetics, the diabetic cohort demonstrated both a higher average length of stay (13.7 vs 9.2 days, p-value=0.0016) and hospitalization cost ($72,883 vs $50,500, p-value=0.0058). Our findings highlight that diabetic patients with lower extremity burns are more likely to develop osteomyelitis than their non-diabetic counterparts and when osteomyelitis is present, diabetic patients have an increased amputation rate. Further study is required to develop protocols to treat this population, with the specific goal of minimizing patient morbidity and optimizing healthcare utilization.

Activated Beta-Catenin Signaling Ameliorates Radiation-Induced Skin Injury by Suppressing Marvel D3 Expression

Radiation-induced skin injury remains a serious concern for cancer radiotherapy, radiation accidents and occupational exposure, and the damage mainly occurs due to apoptosis and reactive oxygen species (ROS) generation. There is currently no effective treatment for this disorder. The β-catenin signaling pathway is involved in the repair and regeneration of injured tissues. However, the role of the β-catenin signaling pathway in radiation-induced skin injury has not been reported. In this study, we demonstrated that the β-catenin signaling pathway was activated in response to radiation and that its activation by Wnt3a, a ligand-protein involved in the β-catenin signaling pathway, inhibited apoptosis and the production of ROS in irradiated human keratinocyte HaCaT cells and skin fibroblast WS1 cells. Additionally, Wnt3a promoted cell migration after irradiation. In a mouse model of full-thickness skin wounds combined with total-body irradiation, Wnt3a was shown to facilitate skin wound healing. The results from RNA-Seq revealed that 24 genes were upregulated and 154 were downregulated in Wnt3a-treated irradiated skin cells, and these dysregulated genes were mainly enriched in the tight junction pathway. Among them, Marvel D3 showed the most obvious difference. We further found that the activated β-catenin signaling pathway stimulated the phosphorylation of JNK by silencing Marvel D3. Treatment of irradiated cells with SP600125, a JNK inhibitor, augmented ROS production and impeded cell migration. Furthermore, treatment with Wnt3a or transfection with Marvel D3-specific siRNAs could reverse the above effects. Taken together, these findings illustrate that activated β-catenin signaling stimulates the activation of JNK by negatively regulating Marvel D3 to ameliorate radiation-induced skin injury.

Selenomethionine protects hematopoietic stem/progenitor cells against cobalt nanoparticles by stimulating antioxidant actions and DNA repair functions

Hematopoietic stem cells (HSCs) and hematopoietic progenitor cells (HPCs) can differentiate into all blood lineages to maintain hematopoiesis, wound healing, and immune functions. Recently, cobalt-chromium alloy casting implants have been used extensively in total hip replacements; however, cobalt nanoparticles (CoNPs) released from the alloy were toxic to HSCs and HPCs. We aimed to investigate the mechanism underlying the toxic effect of CoNPs on HSCs/HPCs and to determine the protective effect of selenomethionine (SeMet) against CoNPs in vitro and in vivo. Human and rat CD34+ HSCs/HPCs were isolated from cord blood and bone marrow, respectively. CoNPs decreased the viability of CD34+ HSCs/HPCs and increased apoptosis. SeMet attenuated the toxicity of CoNPs by enhancing the antioxidant ability of cells. The protective effect of SeMet was not completely abolished after adding H2O2 to abrogate the improvement of the antioxidant capacity by SeMet. SeMet and CoNPs stimulated ATM/ATR DNA damage response signals and inhibited cell proliferation. Unlike CoNPs, SeMet did not damage the DNA, and cell proliferation recovered after removing SeMet. SeMet inhibited the CoNP-induced upregulation of hypoxia inducible factor (HIF)-1α, thereby disrupting the inhibitory effect of HIF-1α on breast cancer type 1 susceptibility protein (BRCA1). Moreover, SeMet promoted BRCA1-mediated ubiquitination of cyclin B by upregulating UBE2K. Thus, SeMet enhanced cell cycle arrest and DNA repair post-CoNP exposure. Overall, SeMet protected CD34+ HSCs/HPCs against CoNPs by stimulating antioxidant activity and DNA repair.

Epigenetic regulation of cellular functions in wound healing

Stringent spatiotemporal regulation of the wound healing process involving multiple cell types is associated with epigenetic mechanisms of gene regulation, such as DNA methylation, histone modification and chromatin remodelling, as well as non-coding RNAs. Here, we discuss the epigenetic changes that occur during wound healing and the rapidly expanding understanding of how these mechanisms affect healing resolution in both acute and chronic wound milieu. We provide a focussed overview of current research into epigenetic regulators that contribute to wound healing by specific cell type. We highlight the role of epigenetic regulators in the molecular pathophysiology of chronic wound conditions. The understanding of how epigenetic regulators can affect cellular functions during normal and impaired wound healing could lead to novel therapeutic approaches, and we outline questions that can provide guidance for future research on epigenetic-based interventions to promote healing. Dissecting the dynamic interplay between cellular subtypes involved in wound healing and epigenetic parameters during barrier repair will deepen our understanding of how to improve healing outcomes in patients affected by chronic non-healing wounds.

The progress, prospects, and challenges of the use of non-coding RNA for diabetic wounds

Chronic diabetic wounds affect the quality of life of patients, resulting in significant social and economic burdens on both individuals and the health care system. Although treatment methods for chronic diabetic wounds have been explored, there remains a lack of effective treatment strategies; therefore, alternative strategies must be explored. Recently, the abnormal expression of non-coding RNA in diabetic wounds has received widespread attention since it is an important factor in the development of diabetic wounds. This article reviews the regulatory role of three common non-coding RNAs (microRNA [miRNA], long non-coding RNA [lncRNA], and circular RNA [circRNA]) in diabetic wounds and discusses the diagnosis, treatment potential, and challenges of non-coding RNA in diabetic wounds. This article provides insights into new strategies for diabetic wound diagnosis and treatment at the genetic and molecular levels.

Antimicrobial properties of olive oil phenolic compounds and their regenerative capacity towards fibroblast cells

Some micronutrients of vegetable origin are considered potentially useful as wound-healing agents because they can increase fibroblast proliferation and differentiation.

THE AIM OF THIS STUDY

was to evaluate the regenerative effects of selected olive oil phenolic compounds on cultured human fibroblasts and explore their antimicrobial properties.

MATERIAL AND METHODS

The CCD-1064Sk fibroblast line was treated for 24 h with 10^-6M luteolin, apigenin, ferulic, coumaric acid or caffeic acid, evaluating the effects on cell proliferation by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) spectrophotometric assay; the migratory capacity by the scratch assay and determining the expression of Fibroblast Growth Factor (FGF), Vascular Endothelial Growth Factor (VEGF), Transforming Growth Factor- β1 (TGFβ1), Platelet Derived Growth Factor (PDGF), and Collagen Type I (COL-I) genes by real-time polymerase chain reaction. The antimicrobial capacity of the polyphenols was evaluated by the disc diffusion method.

RESULTS

All compounds except for ferulic acid significantly stimulated the proliferative capacity of fibroblasts, increasing their migration and their expression of the aforementioned genes. With respect to their antimicrobial properties, treatment with the studied compounds inhibited the growth of Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Proteus spp., and Candida Albicans.

CONCLUSIONS

The phenolic compounds in olive oil have a biostimulatory effect on the regeneration capacity, differentiation, and migration of fibroblasts and exert major antibacterial activity. According to the present findings, these compounds may have a strong therapeutic effect on wound recovery.

Chronic Diabetic Wounds and Their Treatment with Skin Substitutes

With the global prevalence of type 2 diabetes mellitus steeply rising, instances of chronic, hard-healing, or non-healing diabetic wounds and ulcers are predicted to increase. The growing understanding of healing and regenerative mechanisms has elucidated critical regulators of this process, including key cellular and humoral components. Despite this, the management and successful treatment of diabetic wounds represents a significant therapeutic challenge. To this end, the development of novel therapies and biological dressings has gained increased interest. Here we review key differences between normal and chronic non-healing diabetic wounds, and elaborate on recent advances in wound healing treatments with a particular focus on biological dressings and their effect on key wound healing pathways.

Pterostilbene accelerates wound healing by modulating diabetes-induced estrogen receptor β suppression in hematopoietic stem cells

Background

Delayed wound healing is one of the major complications of diabetes mellitus and is characterized by prolonged inflammation, delayed re-epithelialization and consistent oxidative stress, although the detailed mechanism remains unknown. In this study, we aimed to investigate the potential role and effect of pterostilbene (PTE) and hematopoietic stem cells (HSCs) on diabetic wound healing.

Methods

Diabetic rats were used to measure the epigenetic changes in both HSCs and peripheral blood mononuclear cells (PBMCs). A cutaneous burn injury was induced in the rats and PTE-treated diabetic HSCs were transplanted for evaluation of wound healing. In addition, several biomedical parameters, including gene expression, oxidative stress, mitochondrial function and inflammation in macrophages, were also measured.

Results

Our data showed that PTE had a much stronger effect than resveratrol on accelerating diabetic wound healing, likely because PTE can ameliorate diabetes-induced epigenetic changes to estrogen receptor β promoter in HSCs, while resveratrol cannot. Further investigation showed that bone marrow transplantation of PTE-treated diabetic HSCs restores diabetes-induced suppression of estrogen receptor β and its target genes, including nuclear respiratory factor-1 and superoxide dismutase 2, and protects against diabetes-induced oxidative stress, mitochondrial dysfunction and elevated pro-inflammatory cytokines in both PBMCs and macrophages, subsequently accelerating cutaneous wound healing.

Conclusions

HSC may play an important role in wound healing through transferring epigenetic modifications to subsequent PBMCs and macrophages by differentiation, while PTE accelerates diabetic wound healing by modulating diabetes-induced epigenetic changes in HSCs. Thus, PTE may be a novel therapeutic strategy for diabetic wound healing.

Dermal Drivers of Injury-Induced Inflammation: Contribution of Adipocytes and Fibroblasts

Irregular inflammatory responses are a major contributor to tissue dysfunction and inefficient repair. Skin has proven to be a powerful model to study mechanisms that regulate inflammation. In particular, skin wound healing is dependent on a rapid, robust immune response and subsequent dampening of inflammatory signaling. While injury-induced inflammation has historically been attributed to keratinocytes and immune cells, a vast body of evidence supports the ability of non-immune cells to coordinate inflammation in numerous tissues and diseases. In this review, we concentrate on the active participation of tissue-resident adipocytes and fibroblasts in pro-inflammatory signaling after injury, and how altered cellular communication from these cells can contribute to irregular inflammation associated with aberrant wound healing. Furthering our understanding of how tissue-resident mesenchymal cells contribute to inflammation will likely reveal new targets that can be manipulated to regulate inflammation and repair.

Epigenetic Remodeling in Innate Immunity and Inflammation

The innate immune response is a rapid response to pathogens or danger signals. It is precisely activated not only to efficiently eliminate pathogens but also to avoid excessive inflammation and tissue damage. cis-Regulatory element-associated chromatin architecture shaped by epigenetic factors, which we define as the epiregulome, endows innate immune cells with specialized phenotypes and unique functions by establishing cell-specific gene expression patterns, and it also contributes to resolution of the inflammatory response. In this review, we focus on two aspects: (a) how niche signals during lineage commitment or following infection and pathogenic stress program epiregulomes by regulating gene expression levels, enzymatic activities, or gene-specific targeting of chromatin modifiers and (b) how the programed epiregulomes in turn mediate regulation of gene-specific expression, which contributes to controlling the development of innate cells, or the response to infection and inflammation, in a timely manner. We also discuss the effects of innate immunometabolic rewiring on epiregulomes and speculate on several future challenges to be encountered during the exploration of the master regulators of epiregulomes in innate immunity and inflammation.

Glycocalyx disruption enhances motility, proliferation and collagen synthesis in diabetic fibroblasts

Impaired wound healing represents one of the most debilitating side effects of Diabetes mellitus. Though the role of fibroblasts in wound healing is well-known, the extent to which their function is altered in the context of diabetes remains incompletely understood. Here, we address this question by comparing the phenotypes of healthy dermal fibroblasts (HDFs) and diabetic dermal fibroblasts (DDFs). We show that DDFs are more elongated but less motile and less contractile than HDFs. Reduced motility of DDFs is attributed to formation of larger focal adhesions stabilized by a bulky glycocalyx, associated with increased expression of the cell surface glycoprotein mucin 16 (MUC 16). Disruption of the glycocalyx not only restored DDF motility to levels comparable to that of HDFs, but also led to increased proliferation and collagen synthesis. Collectively, our results illustrate the influence of glycocalyx disruption on mechanics of diabetic fibroblasts relevant to cell motility.

DNA maintenance methylation enzyme Dnmt1 in satellite cells is essential for muscle regeneration

Epigenetic transcriptional regulation is essential for the differentiation of various types of cells, including skeletal muscle cells. DNA methyltransferase 1 (Dnmt1) is responsible for maintenance of DNA methylation patterns via cell division. Here, we investigated the relationship between Dnmt1 and skeletal muscle regeneration. We found that Dnmt1 is upregulated in muscles during regeneration. To assess the role of Dnmt1 in satellite cells during regeneration, we performed conditional knockout (cKO) of Dnmt1 specifically in skeletal muscle satellite cells using Pax7CreERT2 mice and Dnmt1 flox mice. Muscle weight and the cross-sectional area after injury were significantly lower in Dnmt1 cKO mice than in control mice. RNA sequencing analysis revealed upregulation of genes involved in cell adhesion and apoptosis in satellite cells from cKO mice. Moreover, satellite cells cultured from cKO mice exhibited a reduced number of cells. These results suggest that Dnmt1 is an essential factor for muscle regeneration and is involved in positive regulation of satellite cell number.

A Comprehensive Analysis of Unique and Recurrent Copy Number Variations in Alzheimer's Disease and its Related Disorders

BACKGROUND

Copy number variations (CNVs) play an important role in the genetic etiology of various neurological disorders, including Alzheimer's disease (AD). Type 2 diabetes mellitus (T2DM) and major depressive disorder (MDD) were shown to have share mechanisms and signaling pathways with AD.

OBJECTIVE

We aimed to assess CNVs regions that may harbor genes contributing to AD, T2DM, and MDD in 67 Saudi familial and sporadic AD patients, with no alterations in the known genes of AD and genotyped previously for APOE.

METHODS

DNA was analyzed using the CytoScan-HD array. Two layers of filtering criteria were applied. All the identified CNVs were checked in the Database of Genomic Variants (DGV).

RESULTS

A total of 1086 CNVs (565 gains and 521 losses) were identified in our study. We found 73 CNVs harboring genes that may be associated with AD, T2DM or MDD. Nineteen CNVs were novel. Most importantly, 42 CNVs were unique in our studied cohort existing only in one patient. Two large gains on chromosomes 1 and 13 harbored genes implicated in the studied disorders. We identified CNVs in genes that encode proteins involved in the metabolism of amyloid-β peptide (AGRN, APBA2, CR1, CR2, IGF2R, KIAA0125, MBP, RER1, RTN4R, VDR and WISPI) or Tau proteins (CACNAIC, CELF2, DUSP22, HTRA1 and SLC2A14).

CONCLUSION

The present work provided information on the presence of CNVs related to AD, T2DM, and MDD in Saudi Alzheimer's patients.

The Cutaneous Wound Innate Immunological Microenvironment

The skin represents the first line of defense and innate immune protection against pathogens. Skin normally provides a physical barrier to prevent infection by pathogens; however, wounds, microinjuries, and minor barrier impediments can present open avenues for invasion through the skin. Accordingly, wound repair and protection from invading pathogens are essential processes in successful skin barrier regeneration. To repair and protect wounds, skin promotes the development of a specific and complex immunological microenvironment within and surrounding the disrupted tissue. This immune microenvironment includes both innate and adaptive processes, including immune cell recruitment to the wound and secretion of extracellular factors that can act directly to promote wound closure and wound antimicrobial defense. Recent work has shown that this immune microenvironment also varies according to the specific context of the wound: the microbiome, neuroimmune signaling, environmental effects, and age play roles in altering the innate immune response to wounding. This review will focus on the role of these factors in shaping the cutaneous microenvironment and how this ultimately impacts the immune response to wounding.

FOXO activity adaptation safeguards the hematopoietic stem cell compartment in hyperglycemia

Hematopoietic stem cell (HSC) activity is tightly controlled to ensure the integrity of the hematopoietic system during the organism's lifetime. How the HSC compartment maintains its long-term fitness in conditions of chronic stresses associated with systemic metabolic disorders is poorly understood. In this study, we show that obesity functionally affects the long-term function of the most immature engrafting HSC subpopulation. We link this altered regenerative activity to the oxidative stress and the aberrant constitutive activation of the AKT signaling pathway that characterized the obese environment. In contrast, we found minor disruptions of the HSC function in obese mice at steady state, suggesting that active mechanisms could protect the HSC compartment from its disturbed environment. Consistent with this idea, we found that FOXO proteins in HSCs isolated from obese mice become insensitive to their normal upstream regulators such as AKT, even during intense oxidative stress. We established that hyperglycemia, a key condition associated with obesity, is directly responsible for the alteration of the AKT-FOXO axis in HSCs and their abnormal oxidative stress response. As a consequence, we observed that HSCs isolated from a hyperglycemic environment display enhanced resistance to oxidative stress and DNA damage. Altogether, these results indicate that chronic metabolic stresses associated with obesity and/or hyperglycemia affect the wiring of the HSCs and modify their oxidative stress response. These data suggest that the uncoupling of FOXO from its environmental regulators could be a key adaptive strategy that promotes the survival of the HSC compartment in obesity.

Sulfated chitosan rescues dysfunctional macrophages and accelerates wound healing in diabetic mice

Emerging evidence suggests that dysfunctional macrophages can cause chronic inflammation and impair tissue regeneration in diabetic wounds. Therefore, improving macrophage behaviors and functions may improve therapeutic outcomes of current treatments in diabetic wounds. Herein, we present a sulfated chitosan (SCS)-doped Collagen type I (Col I/SCS) hydrogel as a candidate for diabetic wound treatments, and assess its efficacy using streptozocin (STZ)-induced diabetic wound model. Results showed that Col I/SCS hydrogel significantly improved wound closure rate, collagen deposition, and revascularization in diabetic wounds. Flow cytometry analysis and immunofluorescent staining analysis showed that the Col I/SCS hydrogel accelerated the resolution of excessive inflammation by reducing the polarization of M1-like macrophages in chronic diabetic wounds. In addition, ELISA analysis revealed that the Col I/SCS hydrogel reduced the production of pro-inflammatory interleukin (IL)-6 and increased the production of anti-inflammatory cytokines including IL-4 and transforming growth factor-beta 1 (TGF-β1) during wound healing. Moreover, the Col I/SCS hydrogel enhanced the transdifferentiation of macrophages into fibroblasts, which enhanced the formation of collagen and the extracellular matrix (ECM) in wound tissue. We highlight a potential application of manipulating macrophages behaviors in the pathological microenvironment via materials strategy. STATEMENT OF SIGNIFICANCE: Improving the chronic inflammatory microenvironment of diabetic wounds by regulating macrophage behaviors has been of wide concern in recent years. We designed a Col I/SCS hydrogel based on Collagen type I and sulfated chitosan (SCS) without exogenous cells or cytokines, which could significantly improve angiogenesis and resolve chronic inflammation in diabetic wounds, and hence accelerate diabetic wound healing. The Col I/SCS hydrogel could facilitate the polarization of M1-to-M2 macrophages and activate the transdifferentiation of macrophages to fibroblasts. Additionally, the Col I/SCS hydrogel also equilibrated the content of pro-inflammatory and anti-inflammatory cytokines. This strategy may afford a new avenue to improve macrophage functions and accelerate diabetic chronic wound healing.

Ångstrom-scale silver particle-embedded carbomer gel promotes wound healing by inhibiting bacterial colonization and inflammation

Poor wound healing after diabetes or extensive burn remains a challenging problem. Recently, we presented a physical approach to fabricate ultrasmall silver particles from Ångstrom scale to nanoscale and determined the antitumor efficacy of Ångstrom-scale silver particles (AgÅPs) in the smallest size range. Here we used the medium-sized AgÅPs (65.9 ± 31.6 Å) to prepare carbomer gel incorporated with these larger AgÅPs (L-AgÅPs-gel) and demonstrated the potent broad-spectrum antibacterial activity of L-AgÅPs-gel without obvious toxicity on wound healing-related cells. Induction of reactive oxygen species contributed to L-AgÅPs-gel-induced bacterial death. Topical application of L-AgÅPs-gel to mouse skin triggered much stronger effects than the commercial silver nanoparticles (AgNPs)-gel to prevent bacterial colonization, reduce inflammation, and accelerate diabetic and burn wound healing. L-AgÅPs were distributed locally in skin without inducing systemic toxicities. This study suggests that L-AgÅPs-gel represents an effective and safe antibacterial and anti-inflammatory material for wound therapy.

Skin well-being in diabetes: Role of macrophages

Macrophages are key players in wound healing- along with mediating the acute inflammatory response, macrophages activate cutaneous epithelial cells and promote tissue repair. Diabetes complications, including diabetic chronic wounds, are accompanied by persistent inflammation and macrophage malfunction. Several studies indicate that hyperglycemia induces various alterations that affect macrophage function in wound healing including epigenetic changes, imbalance between pro- and anti-inflammatory modulators, and insensitivity to proliferative stimuli. In this review, we briefly summarize recent studies regarding those alterations and their implications on skin well-being in diabetes.

Immune Cell Therapies to Improve Regeneration and Revascularization of Non-Healing Wounds

With the increased prevalence of chronic diseases, non-healing wounds place a significant burden on the health system and the quality of life of affected patients. Non-healing wounds are full-thickness skin lesions that persist for months or years. While several factors contribute to their pathogenesis, all non-healing wounds consistently demonstrate inadequate vascularization, resulting in the poor supply of oxygen, nutrients, and growth factors at the level of the lesion. Most existing therapies rely on the use of dermal substitutes, which help the re-epithelialization of the lesion by mimicking a pro-regenerative extracellular matrix. However, in most patients, this approach is not efficient, as non-healing wounds principally affect individuals afflicted with vascular disorders, such as peripheral artery disease and/or diabetes. Over the last 25 years, innovative therapies have been proposed with the aim of fostering the regenerative potential of multiple immune cell types. This can be achieved by promoting cell mobilization into the circulation, their recruitment to the wound site, modulation of their local activity, or their direct injection into the wound. In this review, we summarize preclinical and clinical studies that have explored the potential of various populations of immune cells to promote skin regeneration in non-healing wounds and critically discuss the current limitations that prevent the adoption of these therapies in the clinics.

Fasciola gigantica excretory-secretory products (FgESPs) modulate the differentiation and immune functions of buffalo dendritic cells through a mechanism involving DNMT1 and TET1

Background

Fasciola gigantica infection threatens the health of both humans and animals in the world. The excretory/secretory products (ESPs) of this fluke has been reported to impair the activation and maturation of immune cells. We have previously shown the influence of F. gigantica ESPs (FgESPs) on the maturation of buffalo dendritic cells (DCs). However, the underlying mechanisms remain unclear. The objective of this study was to investigate the potency of FgESPs in shifting the differentiation and immune functions of buffalo DCs.

Methods

Buffalo DCs were incubated with FgESPs directly or further co-cultured with lymphocytes in vitro. qRT-PCR was employed to determine the gene expression profile of DCs or the mixed cells, and an ELISA was used to measure cytokine levels in the supernatants. Hoechst and Giemsa staining assays, transmission electron microscopy, caspase-3/7 activity test and histone methylation test were performed to determine DC phenotyping, apoptosis and methylation. To investigate the mechanism involved with DNA methylation, a Co-IP assay and immunofluorescent staining assay were performed to observe if there was any direct interaction between FgESPs and DNMT1/TET1 in buffalo DCs, while RNAi technology was employed to knockdown DNMT1 and TET1 in order to evaluate any different influence of FgESPs on DCs when these genes were absent.

Results

qRT-PCR and ELISA data together demonstrated the upregulation of DC2 and Th2/Treg markers in DCs alone and DCs with a mixed lymphocyte reaction (MLR), suggesting a bias of DC2 that potentially directed Th2 differentiation in vitro. DC apoptosis was also found and evidenced morphologically and biochemically, which might be a source of tolerogenic DCs that led to Treg differentiation. In addition, FgESPs induced methylation level changes of histones H3K4 and H3K9, which correlate with DNA methylation. Co-IP and immunofluorescent subcellular localization assays showed no direct interaction between the FgESPs and DNMT1/TET1 in buffalo DCs. The productions of IL-6 and IL-12 were found separately altered by the knockdown of DNMT1 and TET1 in DCs after FgESPs treatment.

Conclusions

FgESPs may induce the DC2 phenotype or the apoptosis of buffalo DCs to induce the downstream Th2/Treg response of T cells, possibly through a DNMT1- or TET1-dependent manner(s).

Melatonin-stimulated MSC-derived exosomes improve diabetic wound healing through regulating macrophage M1 and M2 polarization by targeting the PTEN/AKT pathway

Background

After surgery, wound recovery in diabetic patients may be disrupted due to delayed inflammation, which can lead to undesired consequences, and there is currently a lack of effective measures to address this issue. Mesenchymal stem cell (MSC)-derived exosomes (Exo) have been proven to be appropriate candidates for diabetic wound healing through the anti-inflammatory effects. In this study, we investigated whether melatonin (MT)-pretreated MSCs-derived exosomes (MT-Exo) could exert superior effects on diabetic wound healing, and we attempted to elucidate the underlying mechanism.

Methods

For the evaluation of the anti-inflammatory effect of MT-Exo, in vitro and in vivo studies were performed. For in vitro research, we detected the secreted levels of inflammation-related factors, such as IL-1β, TNF-α and IL-10 via ELISA and the relative gene expression of the IL-1β, TNF-α, IL-10, Arg-1 and iNOS via qRT-PCR and investigated the expression of PTEN, AKT and p-AKT by Western blotting. For in vivo study, we established air pouch model and streptozotocin (STZ)-treated diabetic wound model, and evaluated the effect of MT-Exo by flow cytometry, optical imaging, H&E staining, Masson trichrome staining, immunohistochemical staining, immunofluorescence, and qRT-PCR (α-SMA, collagen I and III).

Results

MT-Exo significantly suppressed the pro-inflammatory factors IL-1β and TNF-α and reduced the relative gene expression of IL-1β, TNF-α and iNOS, while promoting the anti-inflammatory factor IL-10 along with increasing the relative expression of IL-10 and Arg-1, compared with that of the PBS, LPS and the Exo groups in vitro. This effect was mediated by the increased ratio of M2 polarization to M1 polarization through upregulating the expression of PTEN and inhibiting the phosphorylation of AKT. Similarly, MT-Exo significantly promoted the healing of diabetic wounds by inhibiting inflammation, thereby further facilitating angiogenesis and collagen synthesis in vivo.

Conclusions

MT-Exo could promote diabetic wound healing by suppressing the inflammatory response, which was achieved by increasing the ratio of M2 polarization to M1 polarization through activating the PTEN/AKT signalling pathway, and the pretreatment of MT was proved to be a promising method for treating diabetic wound healing.

Graphical abstract: MT-Exo promotes diabetic wound healing by regulating M1 and M2 macrophage polarization.

Macrophage Dysregulation and Impaired Skin Wound Healing in Diabetes

Monocytes (Mo) and macrophages (Mϕ) play important roles in normal skin wound healing, and dysregulation of wound Mo/Mϕ leads to impaired wound healing in diabetes. Although skin wound Mϕ originate both from tissue resident Mϕ and infiltrating bone marrow-derived Mo, the latter play dominant roles during the inflammatory phase of wound repair. Increased production of bone marrow Mo caused by alterations of hematopoietic stem and progenitor cell (HSPC) niche and epigenetic modifications of HSPCs likely contributes to the enhanced number of wound Mϕ in diabetes. In addition, an impaired transition of diabetic wound Mϕ from “pro-inflammatory” to “pro-healing” phenotypes driven by the local wound environment as well as intrinsic changes in bone marrow Mo is also thought to be partly responsible for impaired diabetic wound healing. The current brief review describes the origin, heterogeneity and function of wound Mϕ during normal skin wound healing followed by discussion of how dysregulated wound Mϕ numbers and phenotype are associated with impaired diabetic wound healing. The review also highlights the possible links between altered bone marrow myelopoiesis and increased Mo production as well as extrinsic and intrinsic factors that drive wound macrophage dysregulation leading to impaired wound healing in diabetes.

Glycation of macrophages induces expression of pro-inflammatory cytokines and reduces phagocytic efficiency

Glycation and the accumulation of advanced glycation end products (AGEs) are known to occur during normal aging but also in the progression of several diseases, such as diabetes. Diabetes type II and aging both lead to impaired wound healing. It has been demonstrated that macrophages play an important role in impaired wound healing, however, the underlying causes remain unknown. Elevated blood glucose levels as well as elevated methylglyoxal (MGO) levels in diabetic patients result in glycation and increase of AGEs. We used MGO to investigate the influence of glycation and AGEs on macrophages. We could show that glycation, but not treatment with AGE-modified serum proteins, increased expression of pro-inflammatory cytokines interleukin 1β (IL-1β) and IL-8 but also affected IL-10 and TNF-α expression, resulting in increased inflammation. At the same time, glycation reduced phagocytic efficiency and led to impaired clearance rates of invading microbes and cellular debris. Our data suggest that glycation contributes to changes of macrophage activity and cytokine expression and therefore could support the understanding of disturbed wound healing during aging and diabetes.

A Review of the Contribution of Mast Cells in Wound Healing: Involved Molecular and Cellular Mechanisms

Mast cells (MCs), apart from their classic role in allergy, contribute to a number of biologic processes including wound healing. In particular, two aspects of their histologic distribution within the skin have attracted the attention of researchers to study their wound healing role; they represent up to 8% of the total number of cells within the dermis and their cutaneous versions are localized adjacent to the epidermis and the subdermal vasculature and nerves. At the onset of a cutaneous injury, the accumulation of MCs and release of proinflammatory and immunomodulatory mediators have been well documented. The role of MC-derived mediators has been investigated through the stages of wound healing including inflammation, proliferation, and remodeling. They contribute to hemostasis and clot formation by enhancing the expression of factor XIIIa in dermal dendrocytes through release of TNF-α, and contribute to clot stabilization. Keratinocytes, by secreting stem cell factor (SCF), recruit MCs to the site. MCs in return release inflammatory mediators, including predominantly histamine, VEGF, interleukin (IL)-6, and IL-8, that contribute to increase of endothelial permeability and vasodilation, and facilitate migration of inflammatory cells, mainly monocytes and neutrophils to the site of injury. MCs are capable of activating the fibroblasts and keratinocytes, the predominant cells involved in wound healing. MCs stimulate fibroblast proliferation during the proliferative phase via IL-4, vascular endothelial growth factor (VEGF), and basic fibroblast growth factor (bFGF) to produce a new extracellular matrix (ECM). MC-derived mediators including fibroblast growth factor-2, VEGF, platelet-derived growth factor (PDGF), TGF-β, nerve growth factor (NGF), IL-4, and IL-8 contribute to neoangiogenesis, fibrinogenesis, or reepithelialization during the repair process. MC activation inhibition and targeting the MC-derived mediators are potential therapeutic strategies to improve wound healing through reduced inflammatory responses and scar formation.

When Good Guys Turn Bad: Bone Marrow's and Hematopoietic Stem Cells' Role in the Pathobiology of Diabetic Complications

Diabetes strongly contributes to the development of cardiovascular disease, the leading cause of mortality and morbidity in these patients. It is widely accepted that hyperglycemia impairs hematopoietic stem/progenitor cell (HSPC) mobilization from the bone marrow (BM) by inducing stem cell niche dysfunction. Moreover, a recent study demonstrated that type 2 diabetic patients are characterized by significant depletion of circulating provascular progenitor cells and increased frequency of inflammatory cells. This unbalance, potentially responsible for the reduction of intrinsic vascular homeostatic capacity and for the establishment of a low-grade inflammatory status, suggests that bone BM-derived HSPCs are not only victims but also active perpetrators in diabetic complications. In this review, we will discuss the most recent literature on the molecular mechanisms underpinning hyperglycemia-mediated BM dysfunction and differentiation abnormality of HSPCs. Moreover, a section will be dedicated to the new glucose-lowering therapies that by specifically targeting the culprits may prevent or treat diabetic complications.

Systematic review and meta-analysis of mouse models of diabetes-associated ulcers

Mouse models are frequently used to study diabetes-associated ulcers, however, whether these models accurately simulate impaired wound healing has not been thoroughly investigated. This systematic review aimed to determine whether wound healing is impaired in mouse models of diabetes and assess the quality of the past research. A systematic literature search was performed of publicly available databases to identify original articles examining wound healing in mouse models of diabetes. A meta-analysis was performed to examine the effect of diabetes on wound healing rate using random effect models. A meta-regression was performed to examine the effect of diabetes duration on wound healing impairment. The quality of the included studies was also assessed using two newly developed tools. 77 studies using eight different models of diabetes within 678 non-diabetic and 720 diabetic mice were included. Meta-analysis showed that wound healing was impaired in all eight models. Meta-regression suggested that longer duration of diabetes prior to wound induction was correlated with greater degree of wound healing impairment. Pairwise comparisons suggested that non-obese diabetic mice exhibited more severe wound healing impairment compared with db/db mice, streptozotocin-induced diabetic mice or high-fat fed mice at an intermediate stage of wound healing (p<0.01). Quality assessment suggested that the prior research frequently lacked incorporation of key clinically relevant characteristics. This systematic review suggested that impaired wound healing can be simulated in many different mouse models of diabetes but these require further refinement to become more clinically relevant.

HIF1α overexpression enhances diabetic wound closure in high glucose and low oxygen conditions by promoting adipose-derived stem cell paracrine function and survival

Background

Adipose-derived stem cell (ADSC) transplantation is a promising strategy to promote wound healing because of the paracrine function of stem cells. However, glucose-associated effects on stem cell paracrine function and survival contribute to impaired wound closure in patients with diabetes, limiting the efficacy of ADSC transplantation. Hypoxia-inducible factor (HIF)1α plays important roles in wound healing, and in this study, we investigated the effects of HIF1α overexpression on ADSCs in high glucose and low oxygen conditions.

Methods

Adipose samples were obtained from BALB/C mice, and ADSCs were cultured in vitro by digestion. Control and HIF1α-overexpressing ADSCs were induced by transduction. The mRNA and protein levels of angiogenic growth factors in control and HIF1α-overexpressing ADSCs under high glucose and low oxygen conditions were analyzed by quantitative reverse transcription-polymerase chain reaction and western blotting. The effects of ADSC HIF1α overexpression on the proliferation and migration of mouse aortic endothelial cells (MAECs) under high glucose were evaluated using an in vitro coculture model. Intracellular reactive oxygen species (ROS) and 8-hydroxydeoxyguanosine (8-OHdG) levels in ADSCs were observed using 2,7-dichlorodihydrofluorescein diacetate staining and enzyme-linked immunosorbent assays, respectively. Apoptosis and cell cycle analysis assays were performed by flow cytometry. An in vivo full-thickness skin defect mouse model was used to evaluate the effects of transplanted ADSCs on diabetic wound closure.

Results

In vitro, HIF1α overexpression in ADSCs significantly increased the expression of vascular endothelial growth factor A, fibroblast growth factor 2, and C-X-C motif chemokine ligand 12, which were inhibited by high glucose. HIF1α overexpression in ADSCs alleviated high glucose-induced defects in MAEC proliferation and migration and significantly suppressed ADSC ROS and 8-OHdG levels, thereby decreasing apoptosis and enhancing survival. In vivo, HIF1α overexpression in ADSCs prior to transplantation significantly enhanced angiogenic growth factor expression, promoting wound closure in diabetic mice.

Conclusions

HIF1α overexpression in ADSCs efficiently alleviates high glucose-induced paracrine dysfunction, decreases oxidative stress and subsequent DNA damage, improves viability, and enhances the therapeutic effects of ADSCs on diabetic wound healing.

Hydrogen sulfide rescues high glucose-induced migration dysfunction in HUVECs by upregulating miR-126-3p

Diabetes (especially Type II) is one of the primary threats to cardiovascular health. Wound healing defects and vascular dysfunction are common in diabetic patients, and the primary cause of deterioration is sustained high plasma glucose. microRNA, a noncoding RNA, has regulatory functions that are critical to maintaining homeostasis. MicroRNA (miR)-126-3p is a potential diabetes biomarker and a proangiogenic factor, and its plasma level decreases in diabetic patients. Previous studies have revealed the proangiogenic character of the gasotransmitter hydrogen sulfide (H₂S). However, little is known about the relationship between H₂S and miR-126-3p when the extracellular glucose level is high, let alone their influences on deteriorated endothelial cell migration, a key component of angiogenesis, which is crucial for wound healing. Human umbilical vein endothelial cells (HUVECs) were treated with high glucose (33.3 mmol/L) or normal glucose (5.5 mmol/L) for 48 h. Affymetrix miRNA profiling and real-time PCR were used to validate the miRNA expression. An H₂S probe (HSip-1) was used to detect endogenous H₂S. Scratch wound-healing assays were used to evaluate HUVEC migration. The protein levels were quantified by Western blot. Both exogenous and endogenous H₂S could upregulate the miR-126-3p levels in HUVECs or muscle tissue. High glucose decreased the H₂S level and the protein expression of the H₂S-producing enzyme cystathionine γ-lyase (CSE) in HUVECs; however, the DNA methyltransferase 1 (DNMT1) protein level was upregulated. CSE overexpression not only increased the miR-126-3p level by decreasing the DNMT1 protein level but also rescued the deteriorated cell migration in HUVECs treated with high glucose. DNMT1 overexpression decreased the miR-126-3p level and inhibited the migration of HUVECs, whereas silencing DNMT1 improved cell migration. High glucose decreased the endogenous H₂S and miR-126-3p levels and increased the DNMT1 expression, thus inducing the migration dysfunction of HUVECs. Treatment with exogenous H₂S or the overexpression of the endogenously produced enzyme CSE would rescue this migration dysfunction through H₂S-DNMT1-miR-126-3p.

TNF-α regulates diabetic macrophage function through the histone acetyltransferase MOF

A critical component of wound healing is the transition from the inflammatory phase to the proliferation phase to initiate healing and remodeling of the wound. Macrophages are critical for the initiation and resolution of the inflammatory phase during wound repair. In diabetes, macrophages display a sustained inflammatory phenotype in late wound healing characterized by elevated production of inflammatory cytokines, such as TNF-α. Previous studies have shown that an altered epigenetic program directs diabetic macrophages toward a proinflammatory phenotype, contributing to a sustained inflammatory phase. Males absent on the first (MOF) is a histone acetyltransferase (HAT) that has been shown be a coactivator of TNF-α signaling and promote NF-κB-mediated gene transcription in prostate cancer cell lines. Based on MOF's role in TNF-α/NF-κB-mediated gene expression, we hypothesized that MOF influences macrophage-mediated inflammation during wound repair. We used myeloid-specific Mof-knockout (Lyz2Cre Moffl/fl) and diet-induced obese (DIO) mice to determine the function of MOF in diabetic wound healing. MOF-deficient mice exhibited reduced inflammatory cytokine gene expression. Furthermore, we found that wound macrophages from DIO mice had elevated MOF levels and higher levels of acetylated histone H4K16, MOF's primary substrate of HAT activity, on the promoters of inflammatory genes. We further identified that MOF expression could be stimulated by TNF-α and that treatment with etanercept, an FDA-approved TNF-α inhibitor, reduced MOF levels and improved wound healing in DIO mice. This report is the first to our knowledge to define an important role for MOF in regulating macrophage-mediated inflammation in wound repair and identifies TNF-α inhibition as a potential therapy for the treatment of chronic inflammation in diabetic wounds.

Hypercholesterolemia Accelerates the Aging Phenotypes of Hematopoietic Stem Cells by a Tet1-Dependent Pathway

Hypercholesterolemia accelerates the phenotypes of aging in hematopoietic stem cells (HSCs). As yet, little is known about the underlying mechanism. We found that hypercholesterolemia downregulates Ten eleven translocation 1 (Tet1) in HSCs. The total HSC population was increased, while the long-term (LT) population, side population and reconstitution capacity of HSCs were significantly decreased in Tet1^−/− mice. Expression of the Tet1 catalytic domain in HSCs effectively restored the LT population and reconstitution capacity of HSCs isolated from Tet1^−/− mice. While Tet1 deficiency upregulated the expression of p19 and p21 in HSCs by decreasing the H3K27me3 modification, the restoration of Tet1 activity reduced the expression of p19, p21 and p27 by restoring the H3K27me3 and H3K36me3 modifications on these genes. These results indicate that Tet1 plays a critical role in maintaining the quiescence and reconstitution capacity of HSCs and that hypercholesterolemia accelerates HSC aging phenotypes by decreasing Tet1 expression in HSCs.

Genome wide analysis of gene expression changes in skin from patients with type 2 diabetes

Non-healing chronic ulcers are a serious complication of diabetes and are a major healthcare problem. While a host of treatments have been explored to heal or prevent these ulcers from forming, these treatments have not been found to be consistently effective in clinical trials. An understanding of the changes in gene expression in the skin of diabetic patients may provide insight into the processes and mechanisms that precede the formation of non-healing ulcers. In this study, we investigated genome wide changes in gene expression in skin between patients with type 2 diabetes and non-diabetic patients using next generation sequencing. We compared the gene expression in skin samples taken from 27 patients (13 with type 2 diabetes and 14 non-diabetic). This information may be useful in identifying the causal factors and potential therapeutic targets for the prevention and treatment of diabetic related diseases.

Monocytes and Macrophages as Protagonists in Vascular Complications of Diabetes

With the increasing prevalence of diabetes worldwide, vascular complications of diabetes are also on the rise. Diabetes results in an increased risk of macrovascular complications, with atherosclerotic cardiovascular disease (CVD) being the leading cause of death in adults with diabetes. The exact mechanisms for how diabetes promotes CVD risk are still unclear, although it is evident that monocytes and macrophages are key players in all stages of atherosclerosis both in the absence and presence of diabetes, and that phenotypes of these cells are altered by the diabetic environment. Evidence suggests that at least five pro-atherogenic mechanisms involving monocytes and macrophages contribute to the accelerated atherosclerotic lesion progression and hampered lesion regression associated with diabetes. These changes include (1) increased monocyte recruitment to lesions; (2) increased inflammatory activation; (3) altered macrophage lipid accumulation and metabolism; (4) increased macrophage cell death; and (5) reduced efferocytosis. Monocyte and macrophage phenotypes and mechanisms have been revealed mostly by different animal models of diabetes. The roles of specific changes in monocytes and macrophages in humans with diabetes remain largely unknown. There is an ongoing debate on whether the changes in monocytes and macrophages are caused by altered glucose levels, insulin deficiency or insulin resistance, lipid abnormalities, or combinations of these factors. Current research in humans and mouse models suggests that reduced clearance of triglyceride-rich lipoproteins and their remnants is one important mechanism whereby diabetes adversely affects macrophages and promotes atherosclerosis and CVD risk. Although monocytes and macrophages readily respond to the diabetic environment and can be seen as protagonists in diabetes-accelerated atherosclerosis, they are likely not instigators of the increased CVD risk.

MicroRNA Targeting Nicotinamide Adenine Dinucleotide Phosphate Oxidases in Cancer

Significance: Reactive oxygen species (ROS) production occurs primarily in the mitochondria as a by-product of cellular metabolism. ROS are also produced by nicotinamide adenine dinucleotide phosphate (NADPH) oxidases in response to growth factors and cytokines by normal physiological signaling pathways. NADPH oxidase, a member of NADPH oxidase (NOX) family, utilizes molecular oxygen (O2) to generate ROS such as hydrogen peroxide and superoxide. Imbalance between ROS production and its elimination is known to be the major cause of various human diseases. NOX family proteins are exclusively involved in ROS production, which makes them attractive target(s) for the treatment of ROS-mediated diseases including cancer. Recent Advances: Molecules such as Keap1/nuclear factor erythroid 2-related factor 2 (Nrf2), N-methyl-d-aspartic acid (NMDA) receptors, nuclear factor-kappaB, KRAS, kallistatin, gene associated with retinoic-interferon-induced mortality-19, and deregulated metabolic pathways are involved in ROS production in association with NADPH oxidase. Critical Issues: Therapeutic strategies targeting NADPH oxidases in ROS-driven cancers are not very effective due to its complex regulatory circuit. Tumor suppressor microRNAs (miRNAs) viz. miR-34a, miR-137, miR-99a, and miR-21a-3p targeting NADPH oxidases are predominantly downregulated in ROS-driven cancers. miRNAs also regulate other cellular machineries such as Keap1/Nrf2 pathway and NMDA receptors involved in ROS production and consequently drug resistance. Here, we discuss the structure, function, and metabolic role of NADPH oxidase, NOX family protein-protein interaction, their association with other pathways, and NADPH oxidase alteration by miRNAs. Moreover, we also discuss and summarize studies on NADPH oxidase associated with various malignancies and their therapeutic implications. Future Directions: Targeting NADPH oxidases through miRNAs appears to be a promising strategy for the treatment of ROS-driven cancer.

Epigenetic Mechanisms in Monocytes/Macrophages Regulate Inflammation in Cardiometabolic and Vascular Disease

Cardiometabolic and vascular disease, with their associated secondary complications, are the leading cause of morbidity and mortality in Western society. Chronic inflammation is a common theme that underlies initiation and progression of cardiovascular disease. In this regard, monocytes/macrophages are key players in the development of a chronic inflammatory state. Over the past decade, epigenetic modifications, such as DNA methylation and posttranslational histone processing, have emerged as important regulators of immune cell phenotypes. Accumulating studies reveal the importance of epigenetic enzymes in the dynamic regulation of key signaling pathways that alter monocyte/macrophage phenotypes in response to environmental stimuli. In this review, we highlight the current paradigms of monocyte/macrophage polarization and the emerging role of epigenetic modification in the regulation of monocyte/macrophage phenotype in obesity, diabetes mellitus, atherosclerosis, and abdominal aortic aneurysms.

Minor C allele of the SNP rs7873784 associated with rheumatoid arthritis and type-2 diabetes mellitus binds PU.1 and enhances TLR4 expression

Toll-like receptor 4 (TLR4) is an innate immunity receptor predominantly expressed on myeloid cells and involved in the development of various diseases, many of them with complex genetics. Here we present data on functionality of single nucleotide polymorphism rs7873784 located in the 3'-untranslated region (3'-UTR) of TLR4 gene and associated with various pathologies involving chronic inflammation. We demonstrate that TLR4 3'-UTR strongly enhanced the activity of TLR4 promoter in U937 human monocytic cell line while minor rs7873784(C) allele created a binding site for transcription factor PU.1 (encoded by SPI1 gene), a known regulator of TLR4 expression. Increased binding of PU.1 further augmented the TLR4 transcription while PU.1 knockdown or complete disruption of the PU.1 binding site abrogated the effect. We hypothesize that additional functional PU.1 site may increase TLR4 expression in individuals carrying minor C variant of rs7873784 and modulate the development of certain pathologies, such as rheumatoid arthritis and type-2 diabetes mellitus.

Epigenetic regulation of macrophages: from homeostasis maintenance to host defense

Macrophages are crucial members of the innate immune response and important regulators. The differentiation and activation of macrophages require the timely regulation of gene expression, which depends on the interaction of a variety of factors, including transcription factors and epigenetic modifications. Epigenetic changes also give macrophages the ability to switch rapidly between cellular programs, indicating the ability of epigenetic mechanisms to affect phenotype plasticity. In this review, we focus on key epigenetic events associated with macrophage fate, highlighting events related to the maintenance of tissue homeostasis, responses to different stimuli and the formation of innate immune memory. Further understanding of the epigenetic regulation of macrophages will be helpful for maintaining tissue integrity, preventing chronic inflammatory diseases and developing therapies to enhance host defense.

Epigenetic Modification in Macrophages: A Promising Target for Tumor and Inflammation-associated Disease Therapy

Macrophages are essential for supporting tissue homeostasis, regulating immune response, and promoting tumor progression. Due to its heterogeneity, macrophages have different phenotypes and functions in various tissues and diseases. It is becoming clear that epigenetic modification playing an essential role in determining the biological behavior of cells. In particular, changes of DNA methylation, histone methylation and acetylation regulated by the corresponding epigenetic enzymes, can directly control macrophages differentiation and change their functions under different conditions. In addition, epigenetic enzymes also have become anti-tumor targets, such as HDAC, LSD1, DNMT, and so on. In this review, we presented an overview of the latest progress in the study of macrophages phenotype and function regulated by epigenetic modifications, including DNA methylation and histone modifications, to better understand how epigenetic modification controls macrophages phenotype and function in inflammation-associated diseases, and the application prospect in anti-tumor.

Diabetes and aortic aneurysm: current state of the art

Aortic aneurysm is a life-threatening disease due to the risk of aortic rupture. The only curative treatment available relies on surgical approaches; drug-based therapies are lacking, highlighting an unmet need for clinical practice. Abdominal aortic aneurysm (AAA) is frequently associated with atherosclerosis and cardiovascular risk factors including male sex, age, smoking, hypertension, and dyslipidaemia. Thoracic aortic aneurysm (TAA) is more often linked to genetic disorders of the extracellular matrix and the contractile apparatus but also share similar cardiovascular risk factors. Intriguingly, a large body of evidence points to an inverse association between diabetes and both AAA and TAA. A better understanding of the mechanisms underlying the negative association between diabetes and aortic aneurysm could help the development of innovative diagnostic and therapeutic approaches to tackle the disease. Here, we summarize current knowledge on the relationship between glycaemic parameters, diabetes, and the development of aortic aneurysm. Cellular and molecular pathways that underlie the protective effect of diabetes itself and its treatment are reviewed and discussed, along with their potential implications for clinical translation.

Lock Stock and Barrel of Wound Healing

Any kind of injury may lead to wound formation. As per World Health Organization Report, "more than 5 million people die each year due to injuries. This accounts for 9% of the world's population death, nearly 1.7 times the number of fatalities that result from HIV/AIDS, tuberculosis and malaria combined. In addition, ten million people suffer from non-fatal injuries which require treatment". This scenario leads to increased health and economic burden worldwide. Rapid wound healing is exigent subject-field in the health care system. It is imperative to be updated on wound care strategies as impaired wound healing may lead to chronic, non-healing wounds and thus further contributes to the national burden. This article is a comprehensive review of wound care strategies. The first and second part of this review article focuses on the understanding of wound, its types and human body's healing mechanism. Wound healing is natural, highly coordinated process that starts on its own, immediately after the injury. However, individual health condition influences the healing process. Discussion of factors affecting wound healing has also been included. Next part includes the detailed review of diverse wound healing strategies that have already been developed for different types of wound. A detailed description of various polymers that may be used has been discussed. Amongst drug delivery systems, oligomers, dendrimers, films, gels, different nano-formulations, like nanocomposites, nanofibers, nanoemulsions and nanoparticles are discussed. Emphasis on bandages has been made in this article.

Asaronic Acid Attenuates Macrophage Activation toward M1 Phenotype through Inhibition of NF-κB Pathway and JAK-STAT Signaling in Glucose-Loaded Murine Macrophages

Macrophage polarization has been implicated in the pathogenesis of obesity and type 2 diabetes, which are recognized as chronic proinflammatory diseases. This study investigated that high level of glucose, similar to lipopolysaccharide (LPS), activated macrophages toward M1 phenotypes and 1-20 μM asaronic acid (AA) counteracted diabetic macrophage activation. AA reduced the LPS-promoted secretion of proinflammatory interleukin (IL)-6 and monocyte chemoattractant protein-1. The LPS markedly elevated the macrophage induction of the M1 markers of Toll-like receptor 4 (TLR4), CD36, and CD68, which was attenuated by AA. Also, the LPS significantly enhanced the nuclear factor (NF)-κB transactivation, signal transducers, and activators of transcription 1 (STAT1)/STAT3 activation and suppressor of cytokine signaling 3 (SOCS3) induction in macrophages. However, AA highly suppressed the aforementioned effects of LPS. Glucose-stimulated macrophages expressed advanced glycation end products (AGEs) and receptor for AGE (RAGE). Administration of 20 μM AA to macrophages partly but significantly attenuated such effects (1.65 ± 0.12 vs 0.95 ± 0.25 times glucose control for AGE; 2.33 ± 0.31 vs 1.40 ± 0.22 times glucose control for RAGE). Furthermore, glucose enhanced the macrophage induction of TLR4 and inducible nitric oxide synthase and IL-6 production, while it demoted the production of anti-inflammatory arginase-1 and IL-10. In contrast, AA reversed the induction of these markers in glucose-loaded macrophages. AA dose-dependently and significantly encumbered NF-κB transactivation, Janus kinase 2 (JAK2) and STAT1/STAT3 activation, and SOCS3 induction upregulated in glucose-supplemented macrophages. These results demonstrated for the first time that AA may limit diabetic macrophage activation toward the M1 phenotype through the inhibition of TLR4-/IL-6-mediated NF-κB/JAK2-STAT signaling entailing AGE-RAGE interaction.

Activation of Angiogenesis and Wound Healing in Diabetic Mice Using NO-Delivery Dinitrosyl Iron Complexes

In diabetes, abnormal angiogenesis due to hyperglycemia and endothelial dysfunction impairs wound healing and results in high risks of diabetic foot ulcers and mortality. Alternative therapeutic methods were attempted to prevent diabetic complications through the activation of endothelial nitric oxide synthase. In this study, direct application of nitric oxide using dinitrosyl iron complexes (DNICs) to promote angiogenesis and wound healing under physiological conditions and in diabetic mice is investigated. Based on in vitro and in vivo studies, DNIC [Fe₂(μ-SCH₂CH₂OH)₂(NO)₄] (DNIC-1) with a sustainable NO-release reactivity (t_1/2 = 27.4 ± 0.5 h at 25 °C and 16.8 ± 1.8 h at 37 °C) activates the NO-sGC-cGMP pathway and displays the best pro-angiogenesis activity overwhelming other NO donors and the vascular endothelial growth factor. Moreover, this pro-angiogenesis effect of DNIC-1 restores the impaired angiogenesis in the ischemic hind limb and accelerates the recovery rate of wound closure in diabetic mice. This study translates synthetic DNIC-1 into a novel therapeutic agent for the treatment of diabetes and highlights its sustainable ^•NO-release reactivity on the activation of angiogenesis and wound healing.

Insights into the Role of DNA Methylation and Protein Misfolding in Diabetes Mellitus

Background:

Diabetes mellitus is a metabolic disorder that is characterized by impaired glucose tolerance resulting from defects in insulin secretion, insulin action, or both. Epigenetic modifications, which are defined as inherited changes in gene expression that occur without changes in gene sequence, are involved in the etiology of diabetes.

Methods:

In this review, we focused on the role of DNA methylation and protein misfolding and their contribution to the development of both type 1 and type 2 diabetes mellitus.

Results:

Changes in DNA methylation in particular are highly associated with the development of diabetes. Protein function is dependent on their proper folding in the endoplasmic reticulum. Defective protein folding and consequently their functions have also been reported to play a role. Early treatment of diabetes has proven to be of great benefit, as even transient hyperglycemia may lead to pathological effects and complications later on. This has been explained by the theory of the development of a metabolic memory in diabetes. The basis for this metabolic memory was attributed to oxidative stress, chronic inflammation, non-enzymatic glycation of proteins and importantly, epigenetic changes. This highlights the importance of linking new therapeutics targeting epigenetic mechanisms with traditional antidiabetic drugs.

Conclusion:

Although new data is evolving on the relation between DNA methylation, protein misfolding, and the etiology of diabetes, more studies are required for developing new relevant diagnostics and therapeutics.

Platelet-Rich Plasma with Endothelial Progenitor Cells Accelerates Diabetic Wound Healing in Rats by Upregulating the Notch1 Signaling Pathway

Diabetic wounds, as a kind of refractory wound, are very difficult to heal. Both endothelial progenitor cell (EPC) transplantation and platelet-rich plasma (PRP) can improve diabetic wound healing to some extent. However, PRP application cannot provide reparative cells, while EPC transplantation cannot replenish the required growth factors for wound healing. Thus, when applied alone, neither of these factors is sufficient for effective wound healing. Furthermore, the proliferation, differentiation, and fate of the transplanted EPCs are not well known. Therefore, in this study, we examined the efficacy of combined PRP application with EPC transplantation in diabetic wound healing. Our results indicated that PRP application improved EPC proliferation and migration. The Notch signaling pathway plays a key role in the regulation of the proliferation and differentiation of stem cells and angiogenesis in wound healing. The application of PRP upregulated the Notch pathway-related gene and protein expression in EPCs. Furthermore, experiments with shNotch1-transfected EPCs indicated that PRP enhanced the function of EPCs by upregulating the Notch1 signaling pathway. In vivo studies further indicated that the combination of PRP and EPC transplantation increased neovascularization, reduced wound size, and improved healing in rat wound models. Thus, PRP application can provide the necessary growth factors for wound healing, while EPC transplantation offers the required cells, indicating that the combination of both is a potent novel approach for treating diabetic wounds.

Metabolic and Epigenetic Action Mechanisms of Antidiabetic Medicinal Plants

Diabetes is a predominant metabolic disease nowadays due to the off-beam lifestyle of diet and reduced physical activity. Complications of the illness include the gene-environment interactions and the downstream genetic and epigenetic consequences, e.g., cardiovascular diseases, tumor progression, retinopathy, nephropathy, neuropathy, polydipsia, polyphagia, polyuria, and weight loss. This review sheds the light on the mechanistic insights of antidiabetic medicinal plants in targeting key organs and tissues involved in regulating blood glucose homeostasis including the pancreas, liver, muscles, adipose tissues, and glucose absorption in the intestine. Diabetes is also involved in modulating major epigenetic pathways such as DNA methylation and histone modification. In this respect, we will discuss the phytochemicals as current and future epigenetic drugs in the treatment of diabetes. In addition, several proteins are common targets for the treatment of diabetes. Some phytochemicals are expected to directly interact with these targets. We lastly uncover modeling studies that predict such plausible interactions. In conclusion, this review article presents the mechanistic insight of phytochemicals in the treatment of diabetes by combining both the cellular systems biology and molecular modeling.