Macrophage PPARγ and impaired wound healing in type 2 diabetes

Orchestration of macrophage polarization dynamics by fibroblast-secreted exosomes during skin wound healing

Macrophages undertake pivotal yet dichotomous functions during skin wound healing, mediating both early pro-inflammatory immune activation and late anti-inflammatory tissue remodeling processes. The timely phenotypic transition of macrophages from inflammatory M1 to pro-resolving M2 activation states is essential for efficient healing. However, the endogenous mechanisms calibrating macrophage polarization in accordance with the evolving tissue milieu remain undefined. Here, we reveal an indispensable immunomodulatory role for fibroblast-secreted exosomes in directing macrophage activation dynamics. Fibroblast exosomes permitted spatiotemporal coordination of macrophage phenotypes independent of direct intercellular contact. Exosomes enhanced macrophage sensitivity to both M1 and M2 polarizing stimuli, yet also accelerated timely switching from M1 to M2 phenotypes. Exosomes inhibition dysregulated macrophage responses resulting in aberrant inflammation and impaired healing, while provision of exogenous fibroblast exosomes corrected defects. Topical application of fibroblast exosomes onto chronic diabetic wounds normalized dysregulated macrophage activation to resolve inflammation and restore productive healing. Our findings elucidate fibroblast-secreted exosomes as remote programmers of macrophage polarization that calibrate immunological transitions essential for tissue repair. Harnessing exosomes represents a previously unreported approach to steer productive macrophage activation states with immense therapeutic potential for promoting healing in chronic inflammatory disorders.

Macrophage and Neutrophil Dysregulation in Diabetic Wounds

SIGNIFICANCE

The incidence of diabetes continues to rise throughout the world in an alarming rate. Diabetic patients often develop diabetic foot ulcers (DFUs), many of which do not heal. Non-healing DFUs are a major cause of hospitalization, amputation, and increased morbidity. Understanding the underlying mechanisms of impaired healing in DFU is crucial for its management.

RECENT ADVANCES

This review focuses on the recent advancements in macrophage and neutrophils in diabetic wounds and DFUs. In particular, we will discuss diabetes-induced dysregulations and dysfunctions of macrophage and neutrophil functions.

CRITICAL ISSUES

It is well established that diabetic wounds are characterized by stalled inflammation that results in impaired healing. Recent findings in the field suggest that dysregulation of macrophages and neutrophils play a critical role in impaired healing in DFUs. The delineation of mechanisms that restore macrophage and neutrophil function in diabetic wound healing is the focus of intense investigation.

FUTURE DIRECTIONS

The breadth of recently generated knowledge on the activity of macrophages and neutrophils in diabetic wound healing is impressive. Experimental models have delineated pathways that hold promise for the treatment of diabetic wounds and DFUs. These pathways may be useful targets for further clinical investigation.

Chemical Constituents from Agave applanata and Its Antihyperglycemic, Anti-inflammatory, and Antimicrobial Activities Associated with Its Tissue Repair Capability

Agave applanata is a Mexican agave whose fresh leaves are employed to prepare an ethanol tonic used to relieve diabetes. It is also applied to skin to relieve varicose and diabetic foot ulcers, including wounds, inflammation, and infections. In this study, the chemical composition of this ethanol tonic is established and its association with antihyperglycemic, anti-inflammatory, antimicrobial, and wound healing activities is discussed. The fresh leaves of A. applanata were extracted with ethanol : H2O (85 : 15). A fraction of this extract was lyophilized, and the remainder was partitioned into CH2Cl2, n-BuOH, and water. CH2Cl2 and n-BuOH fractions were subjected to a successive open column chromatography process. The structure of the isolated compounds was established using nuclear magnetic resonance and mass spectrometry spectra. The antihyperglycemic activity was evaluated through in vivo sucrose and glucose tolerance experiments, as well as ex vivo intestinal absorption and hepatic production of glucose. Wound healing and edema inhibition were assayed in mice. The minimum inhibitory concentrations (MICs) of the hydroalcoholic extract, its fractions, and pure compounds were determined through agar microdilution against the most isolated pathogens from diabetic foot ulcers. Fatty acids, β-sitosterol, stigmasterol, hecogenin (1: ), N-oleyl-D-glucosamine, β-daucosterol, sucrose, myo-inositol, and hecogenin-3-O-α-L-rhamnopyranosyl-(1 → 3)-β-D-xylopyranosyl-(1 → 2)-[β-D-xylopyranosyl-(1 → 3)-β-D-glucopyranosyl-(1 → 3)]-β-D-glucopyranosyl-(1 → 4)-β-D-galactopyranoside (2: ) were characterized. This research provides evidence for the pharmacological importance of A. applanata in maintaining normoglycemia, showing anti-inflammatory activity and antimicrobial effects against the microorganisms frequently found in diabetic foot ulcers. This plant plays an important role in wound healing and accelerated tissue reparation.

Genetic analysis of impaired healing responses after periodontal therapy in type 2 diabetes: Clinical and in vivo studies

OBJECTIVE

This study aims to investigate the mechanisms underlying the impaired healing response by diabetes after periodontal therapy.

BACKGROUND

Outcomes of periodontal therapy in patients with diabetes are impaired compared with those in patients without diabetes. However, the mechanisms underlying impaired healing response to periodontal therapy have not been sufficiently investigated.

MATERIALS AND METHODS

Zucker diabetic fatty (ZDF) and lean (ZL) rats underwent experimental periodontitis by ligating the mandibular molars for one week. The gingiva at the ligated sites was harvested one day after ligature removal, and gene expression was comprehensively analyzed using RNA-Seq. In patients with and without type 2 diabetes (T2D), the corresponding gene expression was quantified in the gingiva of the shallow sulcus and residual periodontal pocket after non-surgical periodontal therapy.

RESULTS

Ligation-induced bone resorption and its recovery after ligature removal were significantly impaired in the ZDF group than in the ZL group. The RNA-Seq analysis revealed 252 differentially expressed genes. Pathway analysis demonstrated the enrichment of downregulated genes involved in the peroxisome proliferator-activated receptor (PPAR) signaling pathway. PPARα and PPARγ were decreased in mRNA level and immunohistochemistry in the ZDF group than in the ZL group. In clinical, probing depth reduction was significantly less in the T2D group than control. Significantly downregulated expression of PPARα and PPARγ were detected in the residual periodontal pocket of the T2D group compared with those of the control group, but not in the shallow sulcus between the groups.

CONCLUSIONS

Downregulated PPAR subtypes expression may involve the impaired healing of periodontal tissues by diabetes.

Abdominal Panniculectomy: Determining the Impact of Diabetes on Adverse Outcomes and Complications

Background: Despite its association with obesity, the relation between diabetes and the abdominal panniculectomy is less well-established. The purpose of this study was to evaluate the result of diabetes on post-panniculectomy complications in a large cohort and to establish the risk factors associated with unfavorable post-operative outcomes. Methods: Patients that underwent a panniculectomy between 2010 and 2018 were identified in PearlDiver, a national insurance claims database, and identified by Current Procedural Terminology code 15380. Patient demographics and comorbidities were elucidated, and various complications were then identified. Descriptive statistics as well as a multivariate analysis were used to evaluate the association of risk factors and complications. Results: A total of 8282 panniculectomy patients were identified-4245 with diabetes, 4037 without. Obesity, tobacco use, and diabetes were all identified as significant risk factors in developing a surgical site infection, wound disruption, as well as needing to undergo reoperation. Diabetic panniculectomy patients had a higher rate of readmission as well as reoperation and sustained a higher rate of surgical complications, even when matched for. Conclusion: Diabetic panniculectomy patients are at a greater risk for developing complications. Identifying potential risk factors in this patient population could help reduce post-operative complications following a panniculectomy.

Chitosan-Based Dressing as a Sustained Delivery System for Bioactive Cytokines

Wounds represent a common occurrence in human life. Consequently, scientific investigations are underway to advance wound healing methodologies, with a notable focus on dressings imbued with biologically active compounds capable of orchestrating the wound microenvironment through meticulously regulated release mechanisms. Among these bioactive agents are cytokines, which, when administered to the wound milieu without appropriate protection, undergo rapid loss of their functional attributes. Within the context of this research, we present a method for fabricating dressings enriched with G-CSF (granulocyte colony-stimulating factor) or GM-CSF (granulocyte-macrophage colony-stimulating factor), showcasing both biological activity and protracted release dynamics. Based on Ligasano, a commercial polyurethane foam dressing, and chitosan crosslinked with TPP (sodium tripolyphosphate), these dressings are noncytotoxic and enable cytokine incorporation. The recovery of cytokines from dressings varied based on the dressing preparation and storage techniques (without modification, drying, freeze-drying followed by storage at 4 °C or freeze-drying followed by storage at 24 °C) and cytokine type. Generally, drying reduced cytokine levels and their bioactivity, especially with G-CSF. The recovery of G-CSF from unmodified dressings was lower compared to GM-CSF (60% vs. 80%). In summary, our freeze-drying approach enables the storage of G-CSF or GM-CSF enriched dressings at 24 °C with minimal cytokine loss, preserving their biological activity and thus enhancing future clinical availability.

Targeting the NOD-Like Receptor Pyrin Domain Containing 3 Inflammasome to Improve Healing of Diabetic Wounds

Significance: Chronic skin wounds are a significant health problem around the world, often leading to amputation and even death. Although persistent inflammation is a hallmark of these poorly healing wounds, few available therapies have been designed to target inflammation. In this review, we summarize available evidence of the role of the NOD-like receptor pyrin domain containing 3 (NLRP3) inflammasome in impaired wound healing and describe strategies to inhibit the inflammasome to improve wound healing. Recent Advances: The NLRP3 inflammasome plays an important physiological role in skin wound healing, during which transient inflammasome activity contributes to both epidermal and dermal healing. In contrast, sustained activity of the NLRP3 inflammasome leads to impaired epidermal and dermal healing associated with diabetes. Of importance, preclinical studies have demonstrated that inhibiting the NLRP3 inflammasome-induced resolution of inflammation, increased granulation tissue formation and collagen deposition, and accelerated reepithelialization and wound closure. Critical Issues: NLRP3 inflammasome inhibitors have appealing potential for translation into therapies for chronic wounds. Although preclinical studies have shown promising results, there is a need for human/clinical studies to evaluate dosing formulations, potential therapeutic effects, dose-response relationships, and possible side effects. Future Directions: Among strategies to inhibit the NLRP3 inflammasome, glyburide, metformin, peroxisome proliferator-activated receptor agonists, and the dipeptidyl peptidase 4 inhibitor saxagliptin appear to be closest to clinical translation, as these drugs are already Food and Drug Administration approved for other indications. Future clinical studies are needed to develop topical formulations of these drugs, and to assess the safety and efficacy of these inhibitors, to improve healing of chronic wounds.

Preadipocytes in human granulation tissue: role in wound healing and response to macrophage polarization

BACKGROUND

Chronic non-healing wounds pose a global health challenge. Under optimized conditions, skin wounds heal by the formation of scar tissue. However, deregulated cell activation leads to persistent inflammation and the formation of granulation tissue, a type of premature scar tissue without epithelialization. Regenerative cells from the wound periphery contribute to the healing process, but little is known about their cellular fate in an inflammatory, macrophage-dominated wound microenvironment.

METHODS

We examined CD45-/CD31-/CD34+ preadipocytes and CD68+ macrophages in human granulation tissue from pressure ulcers (n=6) using immunofluorescence, immunohistochemistry, and flow cytometry. In vitro, we studied macrophage-preadipocyte interactions using primary human adipose-derived stem cells (ASCs) exposed to conditioned medium harvested from IFNG/LPS (M1)- or IL4/IL13 (M2)-activated macrophages. Macrophages were derived from THP1 cells or CD14+ monocytes. In addition to confocal microscopy and flow cytometry, ASCs were analyzed for metabolic (OXPHOS, glycolysis), morphological (cytoskeleton), and mitochondrial (ATP production, membrane potential) changes. Angiogenic properties of ASCs were determined by HUVEC-based angiogenesis assay. Protein and mRNA levels were assessed by immunoblotting and quantitative RT-PCR.

RESULTS

CD45-/CD31-/CD34+ preadipocytes were observed with a prevalence of up to 1.5% of total viable cells in human granulation tissue. Immunofluorescence staining suggested a spatial proximity of these cells to CD68+ macrophages in vivo. In vitro, ASCs exposed to M1, but not to M2 macrophage secretome showed a pro-fibrotic response characterized by stress fiber formation, elevated alpha smooth muscle actin (SMA), and increased expression of integrins ITGA5 and ITGAV. Macrophage-secreted IL1B and TGFB1 mediated this response via the PI3K/AKT and p38-MAPK pathways. In addition, ASCs exposed to M1-inflammatory stress demonstrated reduced migration, switched to a glycolysis-dominated metabolism with reduced ATP production, and increased levels of inflammatory cytokines such as IL1B, IL8, and MCP1. Notably, M1 but not M2 macrophages enhanced the angiogenic potential of ASCs.

CONCLUSION

Preadipocyte fate in wound tissue is influenced by macrophage polarization. Pro-inflammatory M1 macrophages induce a pro-fibrotic response in ASCs through IL1B and TGFB1 signaling, while anti-inflammatory M2 macrophages have limited effects. These findings shed light on cellular interactions in chronic wounds and provide important information for the potential therapeutic use of ASCs in human wound healing.

Red blood cell-mimicking liposomes loading curcumin promote diabetic wound healing

The excessive inflammatory response is known to be a major challenge for diabetic wound healing, while bacteria secreted toxin, α-hemolysin (Hlα), was recently reported to prolong inflammation and delay diabetic wound healing. In this study, we designed a red blood cell membrane (RBCM)-mimicking liposome containing curcumin (named RC-Lip) for the treatment of diabetic wounds. RC-Lips were successfully fabricated using the thin film dispersion method, and the fusion of RBC membrane with the liposomal membrane was confirmed via surface protein analysis. RC-Lips efficiently adsorbed Hlα, thereby reducing the damage and pro-apoptotic effects of Hlα on keratinocytes. Furthermore, they remarkably facilitated liposome uptake into macrophages with advanced curcumin release and regulation of M2 macrophage polarization. In a diabetic mouse and infected wound model, RC-Lips treatment significantly promoted wound healing and re-epithelialization while downregulating interleukin-1β (IL-1β) and upregulating interleukin-10 (IL-10). In summary, the results showed that the spongiform RC-Lips effectively modulate the inflammatory response after adsorbing Hlα and regulating M2 macrophage polarization, leading to a significant promotion of wound healing in diabetic mice. Hence, this study provides a prospective strategy of efficiently mediating inflammatory response for diabetic wounds.

Beta-Catenin Signaling Pathway: Perhaps We Should Start Exploring it for Diabetic Foot Ulcer Healing?

Diabetic foot ulcers (DFUs) remain a common debilitating and costly complication of diabetes mellitus. Indeed, despite all efforts and emerging technologies, many DFUs are difficult to heal and frequently recur. Thus, novel therapeutic approaches are urgently needed. Specific targeting of different molecular and cellular pathways implicated in wound healing emerges as an attractive therapeutic modality to improve outcomes. One of the novel pathways that carry this potential is the wingless-type mouse mammary tumor virus integration site family/beta-catenin signaling pathway (WβcSP). It plays an important role in different stages of wound healing, including inflammation, proliferation, and remodeling. Potential therapeutic implications of WβcSP activation include producing agonists and/or blocking its endogenous inhibitors. Thus, we should perhaps start exploring potential ways of its therapeutic implication to improve DFU healing.

Mechanism of wound repair in diabetic rats using nanosilver-free alginate dressing

OBJECTIVE

Nanosilver-alginate dressing can effectively promote the healing of diabetic wounds in rats. However, due to the potential toxicity of nanosilver, its widespread application in hard-to-heal wound healing is limited. In the present study, the role and potential mechanism of nanosilver-free alginate gel (NSFAG) in the healing process of diabetic wounds were explored.

METHOD

A diabetic rat skin wound model was established, and wounds were treated with saline (NC group), nanosilver gel (NSG group) or nanosilver-free alginate gel (NSFAG group) for seven consecutive days.

RESULTS

NSFAG significantly promoted wound healing and increased the content of protein and hydroxyproline in granulation tissues, and was superior to NSG (p<0.05). Immunohistochemical analyses revealed that the skin wound tissue structure of the NSFAG group was intact, and the number of skin appendages in the dermis layer was significantly higher compared with the NC group and the NSG group (p<0.05). Western blot analysis found that the protein expression of the epidermal stem cell marker molecules CK19 and CK14 as well the proliferation marker of keratinocytes Ki67 in the NSFAG group was significantly higher compared with the NC group or NSG group (p<0.05). Additionally, the proliferation marker of keratinocytes Ki67 in the NSFAG group was significantly higher compared with the NC or NSG group (p<0.05). Immunofluorescence staining analyses indicated that the CK19- and CK14-positive cells were mainly distributed around the epidermis and the newly formed appendages in the NSFAG group, and this result was not observed in the NC or NSG groups.

CONCLUSION

The present findings demonstrate that NSFAG can effectively accelerate wound healing in diabetic rats by promoting epidermal stem cell proliferation and differentiation into skin cells, as well as formation of granulation tissue, suggesting that it can be a potential dressing for diabetic wounds.

Network pharmacology and molecular docking analysis on potential molecular targets and mechanism of action of BRAF inhibitors for application in wound healing

Topical application of BRAF inhibitors has been shown to accelerate wound healing in murine models, which can be extrapolated into clinical applications. The aim of the study was to identify suitable pharmacological targets of BRAF inhibitors and elucidate their mechanisms of action for therapeutic applicability in wound healing, by employing bioinformatics tools including network pharmacology and molecular docking. The potential targets for BRAF inhibitors were obtained from SwissTargetPrediction, DrugBank, CTD, Therapeutic Target Database, and Binding Database. Targets of wound healing were obtained using online databases DisGeNET and OMIM (Online Mendelian Inheritance in Man). Common targets were found by using the online GeneVenn tool. Common targets were then imported to STRING to construct interaction networks. Topological parameters were assessed using Cytoscape and core targets were identified. FunRich was employed to uncover the signaling pathways, cellular components, molecular functions, and biological processes in which the core targets participate. Finally, molecular docking was performed using MOE software. Key targets for the therapeutic application of BRAF inhibitors for wound healing are peroxisome proliferator-activated receptor γ, matrix metalloproteinase 9, AKT serine/threonine kinase 1, mammalian target of rapamycin, and Ki-ras2 Kirsten rat sarcoma viral oncogene homolog. The most potent BRAF inhibitors that can be exploited for their paradoxical activity for wound healing applications are Encorafenib and Dabrafenib. By using network pharmacology and molecular docking, it can be predicted that the paradoxical activity of BRAF inhibitors can be used for their potential application in wound healing.

Granulocyte-macrophage colony-stimulating factor: Conductor of the wound healing orchestra?

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a glycoprotein and is derived from both hemopoietic and nonhemopoietic sources which exert immunomodulatory properties. Various theories have been proposed to explain why some wounds become chronic and non-healing. Generalized suppression of inflammation locally or systemically may impede the body's physiological healing response by crippling the activity of reparative cells within the wound ecosystem. Thus, highlighting the importance of promoting host-directed therapeutics with immunomodulatory properties. The temporal and spatial expression of GM-CSF and GM-CSF receptors in the integumentary system suggests that epithelial-derived GM-CSF functions in an autocrine/paracrine manner. This may positively affect wound healing physiology via local inflammatory regulation promoting macrophage survival. Although diabetes negatively affects multiple aspects of wound healing GM-CSF activation is particularly impacted. Compared to acute/healthy wounds diabetic foot ulcers (DFU) only partially activate GM-CSF activity. There is a deleterious chain of events associated with this unfortunate sequala. DFUs also have a high proportion of monocytes and an absence of activated macrophages which results in an impaired inflammatory response. This may potentially serve as a vital point for GM-CSF to act as a companion diagnostic/theragnostic modality to help modulate the inflammatory response in wound healing. Correcting macrophage immune dysfunction with exogenous GM-CSF may help restore the immune balance in the wound ecosystem and jumpstart the wound healing cascade. Thus, the recognized beneficial role of GM-CSF in immune regulation across many studies provides a rationale for the initiation of the ongoing randomized controlled trials using GM-CSF.

Pharmacological blockade of HDAC3 accelerates diabetic wound healing by regulating macrophage activation

AIMS

Here, we report the effect of histone deacetylase 3 (HDAC3) inhibition associated with macrophage activation, IL-1β expression, angiogenesis and wound healing in diabetic mice.

MAIN METHODS

To determine the expression of HDAC3 in diabetic mice wounds, hyperglycemia was induced in C57BL/6 mice with streptozotocin followed by induction of 6 mm wounds. To understand the effect of HDAC3 selective inhibitor, BG45, wound tissues were isolated for analysing M1/M2 markers expression, immune cells infiltration, angiogenesis and healing factors expression. CD11b⁺F4/80⁺ cells were sorted from the wound tissues and analysed for the expression of M1/M2 markers using RT-qPCR and flow cytometer. In cell based assays, HDAC3 expression was measured in macrophages stimulated with high glucose (HG) plus LPS. Macrophages treated with BG45 and HG + LPS were analysed for the expression of pro-IL-1β, mature IL-1β, oxidative stress and pro-inflammatory (M1) and anti-inflammatory (M2) factors.

KEY FINDINGS

HDAC3 was found to be upregulated in impaired diabetic mice wounds and in macrophages stimulated with HG + LPS. Topical application of BG45 loaded gel accelerated the wound healing in diabetic mice and was evident by improved expression of Collagen-1A, IL-10, TGF-β, and angiogenesis (CD31, VEGF). BG45 treatment decreased the expression of IL-1β, TNF-α, and IL-6 (M1 phenotype), reduced oxidative stress and promoted the expression of Arginase-1 and YM1/2 (M2 phenotype) in macrophages treated with HG + LPS. BG45 also improved the expression of CD11b⁺F4/80⁺CD206⁺ cells in wound tissues and reduced expression of inflammatory markers.

SIGNIFICANCE

HDAC3 is upregulated in diabetic mice wounds and HDAC3 selective inhibitor promotes the wound healing by regulating macrophage activation, angiogenesis and IL-1β.

Recombinant GM-CSF for diseases of GM-CSF insufficiency: Correcting dysfunctional mononuclear phagocyte disorders

Introduction

Endogenous granulocyte-macrophage colony-stimulating factor (GM-CSF), identified by its ability to support differentiation of hematopoietic cells into several types of myeloid cells, is now known to support maturation and maintain the metabolic capacity of mononuclear phagocytes including monocytes, macrophages, and dendritic cells. These cells sense and attack potential pathogens, present antigens to adaptive immune cells, and recruit other immune cells. Recombinant human (rhu) GM-CSF (e.g., sargramostim [glycosylated, yeast-derived rhu GM-CSF]) has immune modulating properties and can restore the normal function of mononuclear phagocytes rendered dysfunctional by deficient or insufficient endogenous GM-CSF.

Methods

We reviewed the emerging biologic and cellular effects of GM-CSF. Experts in clinical disease areas caused by deficient or insufficient endogenous GM-CSF examined the role of GM-CSF in mononuclear phagocyte disorders including autoimmune pulmonary alveolar proteinosis (aPAP), diverse infections (including COVID-19), wound healing, and anti-cancer immune checkpoint inhibitor therapy.

Results

We discuss emerging data for GM-CSF biology including the positive effects on mitochondrial function and cell metabolism, augmentation of phagocytosis and efferocytosis, and immune cell modulation. We further address how giving exogenous rhu GM-CSF may control or treat mononuclear phagocyte dysfunction disorders caused or exacerbated by GM-CSF deficiency or insufficiency. We discuss how rhu GM-CSF may augment the anti-cancer effects of immune checkpoint inhibitor immunotherapy as well as ameliorate immune-related adverse events.

Discussion

We identify research gaps, opportunities, and the concept that rhu GM-CSF, by supporting and restoring the metabolic capacity and function of mononuclear phagocytes, can have significant therapeutic effects. rhu GM-CSF (e.g., sargramostim) might ameliorate multiple diseases of GM-CSF deficiency or insufficiency and address a high unmet medical need.

The importance of inflammation control for the treatment of chronic diabetic wounds

Diabetic chronic wounds cause massive levels of patient suffering and economic problems worldwide. The state of chronic inflammation arises in response to a complex combination of diabetes mellitus-related pathophysiologies. Advanced treatment options are available; however, many wounds still fail to heal, exacerbating morbidity and mortality. This review describes the chronic inflammation pathophysiologies in diabetic ulcers and treatment options that may help address this dysfunction either directly or indirectly. We suggest that treatments to reduce inflammation within these complex wounds may help trigger healing.

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.

PAQR3 depletion accelerates diabetic wound healing by promoting angiogenesis through inhibiting STUB1-mediated PPARγ degradation

The pathogenesis of diabetic wounds is closely associated with the dysregulation of macrophage polarization. However, the underlying mechanism remains poorly understood. In this study, we aimed to investigate the potential effects of PAQR3 (progestin and adipoQ receptor 3) silencing in accelerating diabetic wound healing. We showed that PAQR3 silencing promoted skin wound healing and angiogenesis in diabetic mice, which was accompanied by enhanced M2 macrophage polarization and elevated expression of PPARγ (peroxisome proliferator-activated receptor γ). PAQR3 silencing also promoted M2 polarization and increased PPARγ protein level in PMA-treated THP-1 cells. Moreover, knockdown of PAQR3 in macrophages enhanced the migration of HaCaT cells and tube formation of HUVECs. The ubiquitination of PPARγ protein in macrophages was repressed by PAQR3 silencing. STUB1 (STIP1 homology and U-box-containing protein 1) binds with the PPARγ protein to mediate PPARγ ubiquitination and degradation in macrophages, which was impaired by PAQR3 silencing. The PPARγ inhibitor, GW9662, or STUB1 overexpression abrogated the enhanced M2 macrophage polarization induced by PAQR3 silencing. Therefore, these findings demonstrates that PAQR3 silencing accelerates diabetic wound healing by promoting M2 macrophage polarization and angiogenesis, which is mediated by the inhibition of STUB1-mediated PPARγ protein ubiquitination and degradation.

Exercise-induced increase in M2 macrophages accelerates wound healing in young mice

Moderate-intensity exercise performed during wound healing has been reported to decrease inflammatory cytokines and chemokines and accelerate wound healing. However, its effect on macrophage phenotype and the mechanism by which exercise accelerates wound healing remain unclear. The purpose of this study was to investigate the effect of exercise on macrophage phenotype during wound healing and to clarify the relationship between angiogenesis and wound healing. 12-week-old male C57BL/6J mice were divided into sedentary (n = 6) and exercise groups (n = 6). The exercise group performed moderate-intensity treadmill running exercise (9.0 m/min, 60 min) for 10 days. Double immunofluorescence analysis was performed using F4/80+ inducible nitric oxide synthase (iNOS)+ for M1 macrophages, F4/80+ transforming growth factor-beta (TGF-β)1+ for M2 macrophages, and CD31+ alpha smooth muscle actin (α-SMA)+ for angiogenesis. The exercise group showed significantly accelerated wound healing compared with the sedentary group. From early wound healing onward, exercise significantly inhibited M1 macrophage infiltration and increased M2 macrophage count. Exercise also significantly increased angiogenesis. Furthermore, the M2 macrophage phenotype was significantly correlated with angiogenesis in the exercise group, indicating that M2 macrophages and angiogenesis are related to accelerated wound healing. These findings suggest that moderate-intensity exercise increases TGF-β1 derived from M2 macrophages, which may be associated with enhanced angiogenesis and wound healing in young mice.

Maresin 1 enhances osteogenic potential of mesenchymal stem cells by modulating macrophage peroxisome proliferator-activated receptor-γ-mediated inflammation resolution

Inflammation resolution plays a significant role in attenuating bone injury aggravated by acute inflammation and maintaining bone homeostasis. Maresin 1 (MaR1), a specialized pro-resolving mediators (SPMs), is biosynthesised in macrophages (Mφs) that regulates acute inflammation. Strategies to accelerate the resolution of inflammation in bone repair include not only promoting vanish of acute inflammation, also improving osteogenic microenvironment. Here, previously prepared difunctional demineralized bone matrix (DBM) scaffold was used to study thoroughly the "cross-talk" between Mφs lipid metabolism and mesenchymal stem cells (MSCs) behaviors in vitro. The pro-resolving mechanism in Mφs treated with MaR1 was elaborated. Furthermore, the biological behaviors of MSCs in co-culture system were evaluated. The results indicated that MaR1 had an enhanced capability and performance in peroxisome proliferator-activated receptor-γ (PPAR-γ) activation, M2-type Mφs polarization, and lipid droplets (LDs) biogenesis in Mφs in vitro. The nuclear receptor PPAR-γ enhanced the anti-inflammatory proteins expression and the polarization of Mφs toward M2 subtype, thereby favoring the proliferation, migration, and osteogenesis of MSCs. Overall, the results verified that MaR1 facilitated MSCs behaviors by regulating PPAR-γ-mediated inflammatory response, which implied that PPAR-γ exhibited a significant role in the dialogue between MSCs behaviors and Mφs lipid metabolism.

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.

Macrophages as a therapeutic target to promote diabetic wound healing

It is well‏ ‏established that macrophages are key regulators of wound healing, displaying impressive plasticity and an evolving phenotype, from an aggressive pro-inflammatory or "M1" phenotype to a pro-healing or "M2" phenotype, depending on the wound healing stage, to ensure proper healing. Because dysregulated macrophage responses have been linked to impaired healing of diabetic wounds, macrophages are being considered as a therapeutic target for improved wound healing. In this review, we first discuss the role of macrophages in a normal skin wound healing process and discuss the aberrations that occur in macrophages under diabetic conditions. Next we provide an overview of recent macrophage-based therapeutic approaches, including delivery of ex-vivo-activated macrophages and delivery of pharmacological strategies aimed at eliminating or re-educating local skin macrophages. In particular, we focus on strategies to silence key regulator genes to repolarize wound macrophages to the M2 phenotype, and we provide a discussion of their potential future clinical translation.

Capsaicin ameliorates diabetic retinopathy by inhibiting poldip2-induced oxidative stress

Background

Oxidative stress and the resultant hyperpermeability play a vital role in the pathogenesis of diabetic retinopathy (DR). Poldip2 has been implicated in H₂O₂ production, but the effects of capsaicin on poldip2 have not been reported.

Methods

Diabetic Sprague-Dawley (SD) rats induced with STZ were treated with capsaicin or AAV₉-poldip2-shRNA, and human retinal microvascular endothelial cells (HRMECs) were treated with capsaicin or poldip2 siRNA.

Results

Current data indicated that the expression of PPARγ, poldip2, Nox4, VCAM-1, HIF-1α, and VEGF increased in rat retinas with DR and in HRMECs treated with high glucose. The production of ROS or H₂O₂ in the tissues, serum, and cells increased, and the paracellular permeability of cultured HRMECs with high glucose significantly increased. In addition, overt hyperpermeability of retinal microvessels and increased retinal neovascularization in diabetic rats were observed. However, capsaicin treatment inhibited these increases and suppressed the expression of PPARγ by enhancing its phosphorylation and ubiquitination in the retinas of DR rats. Poldip2 knockdown in HRMECs or its silencing in the retina of DR rats concomitantly led to reduced levels of Nox4, VCAM-1, HIF-1α, VEGF, ROS, and H₂O₂, and the paracellular permeability of HRMECs or the hyperpermeability of retinal microvessels in diabetic rat retinas decreased. Similarly, after PPARγ knockdown in HRMECs, poldip2, Nox4, HIF-1α, VEGF, ROS, and H₂O₂ decreased, and the monolayer paracellular permeability was reduced accordingly.

Conclusion

Capsaicin may ameliorate diabetic retinopathy by activating TRPV1 and suppressing the PPARγ-poldip2-Nox4 pathway.

Vitamin C and the management of diabetic foot ulcers: a literature review

OBJECTIVE

The lifetime risk of developing a diabetic foot ulcer (DFU) in people with diabetes is as high as 25%. A trio of factors constitute the diabetic foot syndrome that characterises DFUs, including neuropathy, vascular disease and infections. Vitamin C has important functions in the nervous, cardiovascular, and immune systems that are implicated in DFU development. Furthermore, vitamin C deficiency has been observed in individuals with DFUs, suggesting an important function of vitamin C in DFU management and treatment. Therefore, this literature review evaluates the role of vitamin C in the nervous, cardiovascular and immune systems in relation to wound healing and DFUs, as well as discussing vitamin C's lesser known role in depression, a condition that affects many individuals with a DFU.

METHOD

A literature search was done using PubMed, Cochrane Library, Embase, Ovid, Computer Retrieval of Information on Scientific Projects, and NIH Clinical Center. Search terms included 'diabetic foot ulcer,' 'diabetic foot,' 'vitamin C,' and 'ascorbic acid.'

RESULTS

Of the 71 studies initially identified, seven studies met the inclusion criteria, and only three were human clinical trials. Overall, the literature on this subject is limited, with mainly observational and animal studies, and few human clinical trials.

CONCLUSION

There is a need for additional human clinical trials on vitamin C supplementation in individuals with a DFU to fill the knowledge gap and guide clinical practice.

Overexpressing HPGDS in adipose-derived mesenchymal stem cells reduces inflammatory state and improves wound healing in type 2 diabetic mice

Background

In diabetes, delayed wound healing was considered as the result of excessive recruitment and retention of pro-inflammatory cells and factors. Hematopoietic prostaglandin D synthase (HPGDS) was identified from differently expressed genes of diabetic human foot skin. HPGDS is responsible for the production of prostaglandin D2 (PGD2), an inflammatory mediator. Therefore, we aim to explore whether HPGDS could be a therapeutic target in the diabetic wound (DW).

Method

In this study, we compared gene expression profilings of diabetic human foot skin and non-diabetic human foot skin from the Gene Expression Omnibus database. We detected the characteristics of immune components in diabetic mice wound and investigated the role and underlying mechanism of the differently expressed Hpgds for the diabetic wound healing. For in vivo studies, we engineered ADSC to overexpress Hpgds (ADSC^Hpgds) and evaluated its effects on diabetic wound healing using a full-thickness skin wound model. For in vitro studies, we evaluated the role of ADSC^Hpgds conditioned medium and PGD2 on Lipopolysaccharide (LPS) induced macrophage.

Results

Hpgds was significantly down-regulated in type 2 diabetic mice wound and its deficiency delayed normal wound healing. ADSC^Hpgds accelerated DW healing by reducing neutrophil and CD8T cell recruitment, promoting M2 macrophage polarization and increasing the production of growth factors. ADSC^Hpgds conditioned medium showed superior capability in promoting M2 macrophage transition than conditioned medium derived from ADSC alone.

Conclusion

Our results demonstrated that Hpgds is required for wound healing, and ADSC^Hpgds could accelerate DW healing by improving anti-inflammatory state and normalizing the proliferation phase of wound healing in mice. These findings provide a new insight in the therapeutic strategy of diabetic wound.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-03082-w.

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.

A review of current advancements for wound healing: Biomaterial applications and medical devices

Wound healing is a complex process that is critical in restoring the skin's barrier function. This process can be interrupted by numerous diseases resulting in chronic wounds that represent a major medical burden. Such wounds fail to follow the stages of healing and are often complicated by a pro‐inflammatory milieu attributed to increased proteinases, hypoxia, and bacterial accumulation. The comprehensive treatment of chronic wounds is still regarded as a significant unmet medical need due to the complex symptoms caused by the metabolic disorder of the wound microenvironment. As a result, several advanced medical devices, such as wound dressings, wearable wound monitors, negative pressure wound therapy devices, and surgical sutures, have been developed to correct the chronic wound environment and achieve skin tissue regeneration. Most medical devices encompass a wide range of products containing natural (e.g., chitosan, keratin, casein, collagen, hyaluronic acid, alginate, and silk fibroin) and synthetic (e.g., polyvinyl alcohol, polyethylene glycol, poly[lactic‐co‐glycolic acid], polycaprolactone, polylactic acid) polymers, as well as bioactive molecules (e.g., chemical drugs, silver, growth factors, stem cells, and plant compounds). This review addresses these medical devices with a focus on biomaterials and applications, aiming to deliver a critical theoretical reference for further research on chronic wound healing.

Bioactive Poly(octanediol-citrate-polyglycol) Accelerates Skin Regeneration through M2 Polarization Immunomodulating and Early Angiogenesis

The inhibition of inflammation and the promotion of early angiogenesis are paid much attention in skin tissue engineering. Citric acid-based biomaterials are widely used in tissue engineering due to their bioactive structure and biocompatibility, but there are few studies on investigating their role and mechanism in wound repair and skin regeneration. Herein, the potential anti-inflammation mechanism of poly(octanediol-citrate-polyglycol) (POCG) copolymer is reported in regulating skin wound repair. It is found that POCG can modulate macrophages phenotype through downregulating the expression of proinflammatory cytokines (tumor necrosis facor-α (Tnf-α), Interleukin-1β (IL-1β), and Interleukin-6 (IL-6) and polarizing macrophages to anti-inflammatory (M2) phenotype. POCG can promote endothelial cell vascularization by increasing the expression of angiogenesis factors (vascular endothelial growth factor (Vegf) and cluster of differentiation 31CD31) mediated by the macrophage polarization. The in vivo study shows that POCG can accelerate skin wound repair through suppressing the acute inflammation and inducing early angiogenesis through the polarization modulation. Furthermore, the POCG polymer has good biocompatibility for both immune cells and tissue cells. This study may provide the important theoretical support on the bioactivity of citrate-based biomaterials and expanding their applications in tissue engineering.

The macrophage: a key player in the pathophysiology of peripheral neuropathies

Macrophages are present in all mammalian tissues and coexist with various cell types in order to respond to different environmental cues. However, the role of these cells has been underestimated in the context of peripheral nerve damage. More importantly, macrophages display divergent characteristics, associated with their origin, and in response to the modulatory effects of their microenvironment. Interestingly, the advent of new techniques such as fate mapping and single-cell transcriptomics and their synergistic use has helped characterize in detail the origin and fate of tissue-resident macrophages in the peripheral nervous system (PNS). Furthermore, these techniques have allowed a better understanding of their functions from simple homeostatic supervisors to chief regulators in peripheral neuropathies. In this review, we summarize the latest knowledge about macrophage ontogeny, function and tissue identity, with a particular focus on PNS-associated cells, as well as their interaction with reactive oxygen species under physiological and pathological conditions. We then revisit the process of Wallerian degeneration, describing the events accompanying axon degeneration, Schwann cell activation and most importantly, macrophage recruitment to the site of injury. Finally, we review these processes in light of internal and external insults to peripheral nerves leading to peripheral neuropathies, the involvement of macrophages and the potential benefit of the targeting of specific macrophages for the alleviation of functional defects in the PNS.

Molecular characterization, expression and functional analysis of large yellow croaker (Larimichthys crocea) peroxisome proliferator-activated receptor gamma

The peroxisome proliferator-activated receptor gamma (PPARγ) are nuclear receptors with distinct roles in energy metabolism and immunity. Although extensively studied in mammals, immunomodulatory roles of this molecule in teleost fish remain to be investigated. In this study, large yellow croaker (Larimichthys crocea) PPARγ (LcPPARγ) sequence was cloned, which encodes a polypeptide of 541 amino acids that include signature domains belonging to the nuclear receptor superfamily. Phylogenetically, LcPPARγ was most closely related to PPARγ derived from European sea bass (Dicentrarchus labrax). Quantitative analysis shown a ubiquitous expression of this molecule, with highest expression level detected in the intestine. The expression of LcPPARγ was decreased in the intestine, muscle, body kidney, spleen and head kidney-derived monocytes/macrophages (MO/MФs) over the course of Vibrio alginolyticus (V. alginolyticus) infection. In contrast, an up-regulation of LcPPARγ was observed in head kidney-derived MO/MФs following docosahexaenoic acid (DHA) treatment. This increase in LcPPARγ leads to an up-regulation of LcCD11b and LcCD18 and an enhancement of complement-mediated phagocytosis. Furthermore, cytokine secretions of V. alginolyticus-stimulated MO/MФs were modulated following LcPPARγ activations that up-regulated the expression of LcIL-10, while decreased the expression of LcIL-1β, LcTNF-α and LcTGF-β1. Overall, our results indicated that LcPPARγ plays a role in regulating functions of MO/MФs and likely contribute to MO/MФs polarization.

Coiled Coil Crosslinked Alginate Hydrogels Dampen Macrophage-Driven Inflammation

Alginate hydrogels are widely used for tissue engineering and regenerative medicine due to their excellent biocompatibility. A facile and commonly used strategy to crosslink alginate is the addition of Ca²⁺ that leads to hydrogelation. However, extracellular Ca²⁺ is a secondary messenger in activating inflammasome pathways following physical injury or pathogenic insult, which carries the risk of persistent inflammation and scaffold rejection. Here, we present graft copolymers of charge complementary heterodimeric coiled coil (CC) peptides and alginate that undergo supramolecular self-assembly to form Ca²⁺ free alginate hydrogels. The formation of heterodimeric CCs was confirmed using circular dichroism spectroscopy, and scanning electron microscopy revealed a significant difference in crosslink density and homogeneity between Ca²⁺ and CC crosslinked gels. The resulting hydrogels were self-supporting and display shear-thinning and shear-recovery properties. In response to lipopolysaccharide (LPS) stimulation, peritoneal macrophages and bone marrow-derived dendritic cells cultured in the CC crosslinked gels exhibited a 10-fold reduction in secretion of the proinflammatory cytokine IL-1β compared to Ca²⁺ crosslinked gels. A similar response was also observed in vivo upon peritoneal delivery of Ca²⁺ or CC crosslinked gels. Analysis of peritoneal lavage showed that macrophages in mice injected with Ca²⁺ crosslinked gels display a more inflammatory phenotype compared to macrophages from mice injected with CC crosslinked gels. These results suggest that CC peptides by virtue of their tunable sequence-structure-function relationship and mild gelation conditions are promising alternative crosslinkers for alginate and other biopolymer scaffolds used in tissue engineering.

An Integrative Network Approach to Identify Common Genes for the Therapeutics in Tuberculosis and Its Overlapping Non-Communicable Diseases

Tuberculosis (TB) is the leading cause of death from a single infectious agent. The estimated total global TB deaths in 2019 were 1.4 million. The decline in TB incidence rate is very slow, while the burden of noncommunicable diseases (NCDs) is exponentially increasing in low- and middle-income countries, where the prevention and treatment of TB disease remains a great burden, and there is enough empirical evidence (scientific evidence) to justify a greater research emphasis on the syndemic interaction between TB and NCDs. The current study was proposed to build a disease-gene network based on overlapping TB with NCDs (overlapping means genes involved in TB and other/s NCDs), such as Parkinson’s disease, cardiovascular disease, diabetes mellitus, rheumatoid arthritis, and lung cancer. We compared the TB-associated genes with genes of its overlapping NCDs to determine the gene-disease relationship. Next, we constructed the gene interaction network of disease-genes by integrating curated and experimentally validated interactions in humans and find the 13 highly clustered modules in the network, which contains a total of 86 hub genes that are commonly associated with TB and its overlapping NCDs, which are largely involved in the Inflammatory response, cellular response to cytokine stimulus, response to cytokine, cytokine-mediated signaling pathway, defense response, response to stress and immune system process. Moreover, the identified hub genes and their respective drugs were exploited to build a bipartite network that assists in deciphering the drug-target interaction, highlighting the influential roles of these drugs on apparently unrelated targets and pathways. Targeting these hub proteins by using drugs combination or drug repurposing approaches will improve the clinical conditions in comorbidity, enhance the potency of a few drugs, and give a synergistic effect with better outcomes. Thus, understanding the Mycobacterium tuberculosis (Mtb) infection and associated NCDs is a high priority to contain its short and long-term effects on human health. Our network-based analysis opens a new horizon for more personalized treatment, drug-repurposing opportunities, investigates new targets, multidrug treatment, and can uncover several side effects of unrelated drugs for TB and its overlapping NCDs.

The Immune-Centric Revolution in the Diabetic Foot: Monocytes and Lymphocytes Role in Wound Healing and Tissue Regeneration-A Narrative Review

Monocytes and lymphocytes play a key role in physiologic wound healing and might be involved in the impaired mechanisms observed in diabetes. Skin wound macrophages are represented by tissue resident macrophages and infiltrating peripheral blood recruited monocytes which play a leading role during the inflammatory phase of wound repair. The impaired transition of diabetic wound macrophages from pro-inflammatory M1 phenotypes to anti-inflammatory pro-regenerative M2 phenotypes might represent a key issue for impaired diabetic wound healing. This review will focus on the role of immune system cells in normal skin and diabetic wound repair. Furthermore, it will give an insight into therapy able to immuno-modulate wound healing processes toward to a regenerative anti-inflammatory fashion. Different approaches, such as cell therapy, exosome, and dermal substitute able to promote the M1 to M2 switch and able to positively influence healing processes in chronic wounds will be discussed.

Periostin in Angiogenesis and Inflammation in CRC-A Preliminary Observational Study

Background and Objectives: To assess the periostin level and the concentrations of pro-inflammatory cytokines: TNFα, IFN-γ, IL-1β and IL-17 in tumor and marginal tissues of CRC and to investigate the influence of periostin on angiogenesis by MVD (microvessel density) and concentration of VEGF-A in relation to clinicopathological parameters of patients. Materials and Methods: The study used 47 samples of tumor and margin tissues derived from CRC patients. To determinate the concentration of periostin, VEGF-A, TNFα, IFNγ, IL-1β and IL-17, we used the commercially available enzyme- linked immunosorbent assay kit. MVD was assessed on CD34-stained specimens. The MVD and budding were assessed using a light microscope Results: We found significantly higher concentrations of periostin, VEGF-A, IFN-γ, IL-1 β, IL-17 and TNFα in the tumor samples compared with surgical tissue margins. The tumor concentrations of periostin were correlated with tumor levels of VEGF-A, IFN-γ, IL-1β and TNFα. We observed significant correlation between margin periostin and VEGF-A, IFN-γ, IL-17 and TNFα in tumor and margin specimens. Additionally, we found a significantly negative correlation between periostin tumor concentration and microvessel density at the invasive front. Tumor periostin levels were also correlated positively with tumor budding. Conclusions: Periostin activity may be associated with pro-inflammatory cytokine levels: TNFα, IFN-γ, IL-1β and IL-17. Our results also suggest the role of periostin in angiogenesis in CRC and its upregulation in poorly vascularized tumors. Further research on the regulations between periostin and cytokines are necessary to understand the interactions between tumor and immune tumor microenvironment, which could be helpful in the development of new targeted therapy.

Collagen/hyaluronan based hydrogels releasing sulfated hyaluronan improve dermal wound healing in diabetic mice via reducing inflammatory macrophage activity

Sustained inflammation associated with dysregulated macrophage activation prevents tissue formation and healing of chronic wounds. Control of inflammation and immune cell functions thus represents a promising approach in the development of advanced therapeutic strategies. Here we describe immunomodulatory hyaluronan/collagen (HA-AC/coll)-based hydrogels containing high-sulfated hyaluronan (sHA) as immunoregulatory component for the modulation of inflammatory macrophage activities in disturbed wound healing. Solute sHA downregulates inflammatory activities of bone marrow-derived and tissue-resident macrophages in vitro. This further affects macrophage-mediated pro-inflammatory activation of skin cells as shown in skin ex-vivo cultures. In a mouse model of acute skin inflammation, intradermal injection of sHA downregulates the inflammatory processes in the skin. This is associated with the promotion of an anti-inflammatory gene signature in skin macrophages indicating a shift of their activation profile. For in vivo translation, we designed HA-AC/coll hydrogels allowing delivery of sHA into wounds over a period of at least one week. Their immunoregulatory capacity was analyzed in a translational experimental approach in skin wounds of diabetic db/db mice, an established model for disturbed wound healing. The sHA-releasing hydrogels improved defective tissue repair with reduced inflammation, augmented pro-regenerative macrophage activation, increased vascularization, and accelerated new tissue formation and wound closure.

Recovery of Altered Diabetic Myofibroblast Heterogeneity and Gene Expression Are Associated with CD301b+ Macrophages

Diabetic wound healing is associated with impaired function and reduced numbers of myofibroblasts, a heterogeneous cell population with varying capacities to promote repair. To determine how diabetes alters myofibroblast composition, we performed flow cytometry and spatial tissue analysis of myofibroblast subsets throughout the healing process in diabetic (db/db) and control (db/+) mouse skin. We observed reduced numbers of profibrotic SCA1+; CD34+; CD26+ myofibroblasts in diabetic wounds five days after injury, with decreased expression of fibrosis-associated genes compared to myofibroblasts from db/+ mouse wounds. While the abundance of myofibroblasts remained reduced in db/db mouse wounds compared to controls, the altered myofibroblast heterogeneity and gene expression in diabetic mice was improved seven days after injury. The natural correction of myofibroblast composition and gene expression in db/db wound beds temporally corresponds with a macrophage phenotypic switch. Correlation analysis from individual wound beds revealed that wound healing in control mice is associated with CD206+ macrophages, while the rescued myofibroblast phenotypes in diabetic wounds are correlated with increased CD301b+ macrophage numbers. These data demonstrate how diabetes impacts specific subsets of myofibroblasts and indicate that signaling capable of rescuing impaired diabetic wound healing could be different from signals that regulate wound healing under nonpathological conditions.

High-fat diet-associated cognitive decline: Is zinc finger protein 1 (ZPR1) the molecular connection?

Zinc finger protein 1 (ZPR1) is required for cellular replication and viability. Recently, ZPR1 variant rs964184 has been repeatedly linked to high plasma triglyceride levels, metabolic syndrome, type 2 diabetes mellitus (T2DM), and nonalcoholic fatty liver disease (NAFLD), suggesting its involvement in lipid metabolism. This article attempts to explain how ZPR1 contributes to the mechanism of high-fat diet-associated cognitive decline through three premises: i) high-fat diet results in cognitive decline, ii) ZPR1 deficiency also results in cognitive decline, and iii) high-fat diet results in ZPR1 deficiency. Therefore, ZPR1 has the potential to be the connection between high-fat diet and cognitive decline. The two modalities of cognitive decline caused by low concentrations of ZPR1 are reduced brain-derived growth factor (BDNF) synthesis and neuron death, both occurring in the hippocampus. Downregulation of ZPR1 may lead to decreased synthesis of BDNF due to reduced concentrations of peroxisome proliferator-activated receptor-gamma (PPAR-γ), tropomyosin receptor kinase B (Trk B), and cAMP response element-binding protein (CREB), resulting in reduced ability to form and retain long-term memory as well as reduced neuroplasticity. Likewise, low concentrations of ZPR1 facilitate neuron death by producing lower amount of spinal motor neuron (SMN) protein, causing genomic instability, activating mixed-lineage protein kinase 3 (MLK3), mitogen-activated protein kinase 7 (MKK7), and c-Jun N-terminal kinase 3 (JNK3) signal cascade, and ultimately resulting in the activation of Caspase 3.

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ZPR1 plays an important role in cell division and viability.

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ZPR1 variant rs964184 has been linked to dysregulation of lipid metabolism.

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High-fat diet can reduce ZPR1 to induce hippocampal neuronal death.

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High-fat diet correlates with cognitive decline.

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ZPR1 may mediate high-fat diet-induced cognitive decline.

Diabetic Wound-Healing Science

Diabetes mellitus is an increasingly prevalent chronic metabolic disease characterized by prolonged hyperglycemia that leads to long-term health consequences. It is estimated that impaired healing of diabetic wounds affects approximately 25% of all patients with diabetes mellitus, often resulting in lower limb amputation, with subsequent high economic and psychosocial costs. The hyperglycemic environment promotes the formation of biofilms and makes diabetic wounds difficult to treat. In this review, we present updates regarding recent advances in our understanding of the pathophysiology of diabetic wounds focusing on impaired angiogenesis, neuropathy, sub-optimal chronic inflammatory response, barrier disruption, and subsequent polymicrobial infection, followed by current and future treatment strategies designed to tackle the various pathologies associated with diabetic wounds. Given the alarming increase in the prevalence of diabetes, and subsequently diabetic wounds, it is imperative that future treatment strategies target multiple causes of impaired healing in diabetic wounds.

Modulation of macrophage functions by ECM-inspired wound dressings - a promising therapeutic approach for chronic wounds

Nonhealing chronic wounds are among the most common skin disorders with increasing incidence worldwide. However, their treatment is still dissatisfying, that is why novel therapeutic concepts targeting the sustained inflammatory process have emerged. Increasing understanding of chronic wound pathologies has put macrophages in the spotlight of such approaches. Herein, we review current concepts and perspectives of therapeutic macrophage control by ECM-inspired wound dressing materials. We provide an overview of the current understanding of macrophage diversity with particular view on their roles in skin and in physiological and disturbed wound healing processes. Based on this we discuss strategies for their modulation in chronic wounds and how such strategies can be tailored in ECM-inspired wound dressing. The latter utilize and mimic general principles of ECM-mediated cell control, such as binding and delivery of signaling molecules and direct signaling to cells specifically adapted for macrophage regulation in wounds. In this review, we present examples of most recent approaches and discuss ideas for their further development.

[Nutrition in the prevention and healing of chronic wounds. Importance in improving the diabetic foot]

Nutrition plays an essential role in chronic wound healing as extra nutrients are needed for tissue repair and to restore losses through wound exudate. Insufficient intake of energy, protein, antioxidants (vitamin C, A, and zinc) and vitamin D are common in patients with chronic wounds and have been linked to delayed wound healing and dehiscence. Other risk factors such as obesity, diabetes, advanced age, corticosteroid use, and dehydration can also reduce or impede the healing process, and nutritional screening is important to identify patients with malnutrition. Proteins, amino acids (arginine, glutamine and methionine), vitamins C and A, and zinc have been used as pharmacological nutrients in pressure ulcer healing; however, omega-3 fatty acids, although they appear to slow progression, do not show improved healing rates. In patients with diabetic foot, supplementation with vitamins D, C, A, and E, magnesium, zinc, omega-3 fatty acids, and probiotics reduces ulcer size and improves glycemic control, although they have not been associated with complete healing; however, supplementation with arginine, glutamine, and β-hydroxy-β-methylbutyrate does show wound healing, although further evidence is needed to confirm these results.

The influence of a biofilm-dispersing wound gel on the wound healing process

Topical antimicrobials that reduce the bacterial bioburden within a chronically‐infected wound may have helpful or harmful effects on the healing process. We used murine models of full‐thickness skin wounds to determine the effects of the novel biofilm‐dispersing wound gel (BDWG) and its gel base on the healing of uninfected wounds. The rate of wound closure over 19 days was comparable among the BDWG‐treated (BT) wounds and the controls. Compared with the controls, histology of the BT wounds showed formation of a stable blood clot at day 1, more neovascularisation and reepithelialisation at day 3, and more organised healing at day 7. Fluorescence‐activated cell sorting analysis showed a lower percentage of neutrophils in wounded tissues of the BT group at days 1 and 3, and significantly more M2 macrophages at day 3. Levels of proinflammatory cytokines and chemokines were increased over the uninjured baseline within the wounds of all treatment groups but the levels were significantly lower in the BT group at day 1, modulating the inflammatory response. Our results suggest that BDWG does not interfere with the wound healing process and may enhance it by lowering inflammation and allowing transition to the proliferative stage of wound healing by day 3.

The role of lipid-based signalling in wound healing and senescence

Lipid-based signalling modulates several cellular processes and intercellular communication during wound healing and tissue regeneration. Bioactive lipids include but are not limited to the diverse group of eicosanoids, phospholipids, and extracellular vesicles and mediate the attraction of immune cells, initiation of inflammatory responses, and their resolution. In aged individuals, wound healing and tissue regeneration are greatly impaired, resulting in a delayed healing process and non-healing wounds. Senescent cells accumulate with age in vivo, preferably at sites implicated in age-associated pathologies and their elimination was shown to alleviate many age-associated diseases and disorders. In contrast to these findings, the transient presence of senescent cells in the process of wound healing exerts beneficial effects and limits fibrosis. Hence, clearance of senescent cells during wound healing was repeatedly shown to delay wound closure in vivo. Recent findings established a dysregulated synthesis of eicosanoids, phospholipids and extracellular vesicles as part of the senescent phenotype. This intriguing connection between cellular senescence, lipid-based signalling, and the process of wound healing and tissue regeneration prompts us to compile the current knowledge in this review and propose future directions for investigation.

Novel Applications of NSAIDs: Insight and Future Perspectives in Cardiovascular, Neurodegenerative, Diabetes and Cancer Disease Therapy

Once it became clear that inflammation takes place in the modulation of different degenerative disease including neurodegenerative, cardiovascular, diabetes and cancer the researchers has started intensive programs evaluating potential role of non-steroidal anti-inflammatory drugs (NSAIDs) in the prevention or therapy of these diseases. This review discusses the novel mechanism of action of NSAIDs and its potential use in the pharmacotherapy of neurodegenerative, cardiovascular, diabetes and cancer diseases. Many different molecular and cellular factors which are not yet fully understood play an important role in the pathogenesis of inflammation, axonal damage, demyelination, atherosclerosis, carcinogenesis thus further NSAID studies for a new potential indications based on precise pharmacotherapy model are warranted since NSAIDs are a heterogeneous group of medicines with relative different pharmacokinetics and pharmacodynamics profiles. Hopefully the new data from studies will fill in the gap between experimental and clinical results and translate our knowledge into successful disease therapy.

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.

The Emerging Role of COX-2, 15-LOX and PPARγ in Metabolic Diseases and Cancer: An Introduction to Novel Multi-target Directed Ligands (MTDLs)

Emerging evidence supports an intertwining framework for the involvement of different inflammatory pathways in a common pathological background for a number of disorders. Of importance are pathways involving arachidonic acid metabolism by cyclooxygenase-2 (COX-2) and 15-lipoxygenase (15-LOX). Both enzyme activities and their products are implicated in a range of pathophysiological processes encompassing metabolic impairment leading to adipose inflammation and the subsequent vascular and neurological disorders, in addition to various pro- and antitumorigenic effects. A further layer of complexity is encountered by the disparate, and often reciprocal, modulatory effect COX-2 and 15-LOX activities and metabolites exert on each other or on other cellular targets, the most prominent of which is peroxisome proliferator-activated receptor gamma (PPARγ). Thus, effective therapeutic intervention with such multifaceted disorders requires the simultaneous modulation of more than one target. Here, we describe the role of COX-2, 15-LOX, and PPARγ in cancer and complications of metabolic disorders, highlight the value of designing multi-target directed ligands (MTDLs) modifying their activity, and summarizing the available literature regarding the rationale and feasibility of design and synthesis of these ligands together with their known biological effects. We speculate on the potential impact of MTDLs in these disorders as well as emphasize the need for structured future effort to translate these early results facilitating the adoption of these, and similar, molecules in clinical research.

The Dynamic Inflammatory Tissue Microenvironment: Signality and Disease Therapy by Biomaterials

Tissue regeneration is an active multiplex process involving the dynamic inflammatory microenvironment. Under a normal physiological framework, inflammation is necessary for the systematic immunity including tissue repair and regeneration as well as returning to homeostasis. Inflammatory cellular response and metabolic mechanisms play key roles in the well-orchestrated tissue regeneration. If this response is dysregulated, it becomes chronic, which in turn causes progressive fibrosis, improper repair, and autoimmune disorders, ultimately leading to organ failure and death. Therefore, understanding of the complex inflammatory multiple player responses and their cellular metabolisms facilitates the latest insights and brings novel therapeutic methods for early diseases and modern health challenges. This review discusses the recent advances in molecular interactions of immune cells, controlled shift of pro- to anti-inflammation, reparative inflammatory metabolisms in tissue regeneration, controlling of an unfavorable microenvironment, dysregulated inflammatory diseases, and emerging therapeutic strategies including the use of biomaterials, which expand therapeutic views and briefly denote important gaps that are still prevailing.

PPAR Gamma: From Definition to Molecular Targets and Therapy of Lung Diseases

Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear receptor superfamily that regulate the expression of genes related to lipid and glucose metabolism and inflammation. There are three members: PPARα, PPARβ or PPARγ. PPARγ have several ligands. The natural agonists are omega 9, curcumin, eicosanoids and others. Among the synthetic ligands, we highlight the thiazolidinediones, clinically used as an antidiabetic. Many of these studies involve natural or synthetic products in different pathologies. The mechanisms that regulate PPARγ involve post-translational modifications, such as phosphorylation, sumoylation and ubiquitination, among others. It is known that anti-inflammatory mechanisms involve the inhibition of other transcription factors, such as nuclear factor kB(NFκB), signal transducer and activator of transcription (STAT) or activator protein 1 (AP-1), or intracellular signaling proteins such as mitogen-activated protein (MAP) kinases. PPARγ transrepresses other transcription factors and consequently inhibits gene expression of inflammatory mediators, known as biomarkers for morbidity and mortality, leading to control of the exacerbated inflammation that occurs, for instance, in lung injury/acute respiratory distress. Many studies have shown the therapeutic potentials of PPARγ on pulmonary diseases. Herein, we describe activities of the PPARγ as a modulator of inflammation, focusing on lung injury and including definition and mechanisms of regulation, biological effects and molecular targets, and its role in lung diseases caused by inflammatory stimuli, bacteria and virus, and molecular-based therapy.

Toward Developing Immunocompetent Diabetic Foot Ulcer-on-a-Chip Models for Drug Testing

Bioengineering of skin has been significantly explored, ranging from the use of traditional cell culture systems to the most recent organ-on-a-chip (OoC) technology that permits skin modeling on physiological scales among other benefits. This article presents key considerations for developing physiologically relevant immunocompetent diabetic foot ulcer (DFU) models. Diabetic foot ulceration affects hundreds of millions of individuals globally, especially the elderly, and constitutes a major socioeconomic burden. When DFUs are not treated and managed in a timely manner, 15-50% of patients tend to undergo partial or complete amputation of the affected limb. Consequently, at least 40% of such patients die within 5 years postamputation. Currently, therapeutic strategies are actively sought and developed. However, present-day preclinical platforms (animals and in vitro models) are not robust enough to provide reliable data for clinical trials. Insights from published works on immunocompetent skin-on-a-chip models and bioengineering considerations, presented in this article, can inform researchers on how to develop robust OoC models for testing topical therapies such as growth factor-based therapies for DFUs. We propose that immunocompetent DFU-on-a-chip models should be bioengineered using diseased cells derived from individuals; in particular, the pathophysiological contribution of macrophages in diabetic wound healing, along with the typical fibroblasts and keratinocytes, needs to be recapitulated. The ideal model should consist of the following components: diseased cells embedded in reproducible scaffolds, which permit endogenous "diseased" extracellular matrix deposition, and the integration of the derived immunocompetent DFU model onto a microfluidic platform. The proposed DFU platforms will eventually facilitate reliable and robust drug testing of wound healing therapeutics, coupled with reduced clinical trial failure rates. Impact statement Current animal and cell-based systems are not physiologically relevant enough to retrieve reliable results for clinical translation of diabetic foot ulcer (DFU) therapies. Organ-on-a-chip (OoC) technology offers desirable features that could finally enable the vision of modeling DFU for pathophysiological studies and drug testing at a microscale. This article brings together the significant recent findings relevant to developing a minimally functional immunocompetent DFU-on-a-chip model, as wound healing cannot occur without a proper functioning immune response. It looks feasible in the future to recapitulate the stagnant inflammation in DFU (thought to impede wound healing) using OoC, diseased cells, and an endogenously produced extracellular matrix.