Factor VII deficiency impairs cutaneous wound healing in mice

Gallium-modified gelatin nanoparticles loaded with quercetin promote skin wound healing via the regulation of bacterial proliferation and macrophage polarization

Background: Wound healing is a complicated process involving multiple cell components and can help the re-establishment of the skin's barrier function. Previous studies have pointed out that bacterial infection and sustained inflammatory reactions are the main causes of the delay of wound closure and scar formation during wound healing. The effect of current approaches for scar-free wound repair still faces many challenges, and alternative therapeutic methods are urgently needed to be established. Methods: The basic characteristics of the new-designed nanoparticles were clarified through the characterization of the material. The biocompatibility of the nanoparticles, as well as its effect on fibroblast function, anti-bacterial capacity, inflammation suppressive role, and the underlying mechanism were further verified by a panel of biochemical assays in vitro. Ultimately, pre-clinical rat model was employed to testify its role in wound healing and scar formation in vivo. Results: Firstly, gallium-modified gelatin nanoparticles loaded with quercetin was successfully established, displaying good biocompatibility and facilitative effect on fibroblast function. In addition, the nanoparticles showed prominent anti-bacterial and inflammation-suppressive effects. What's more important, the nanoparticles could also induce the polarization of macrophages from M1 to M2 phenotype to exert its inflammatory inhibitory role through TGF-β/Smad signaling pathway. Ultimately, in vivo experiment showed that the nanoparticles could effectively promote wound repair and inhibit scar formation during the process of wound healing. Conclusion: Taken together, the new nanoparticles have good anti-bacterial and anti-scar formation effects and great potential in the field of skin wound repair, which provides a promising therapeutic strategy for wound treatment.

Protease- and cell type-specific activation of protease-activated receptor 2 in cutaneous inflammation

BACKGROUND

Protease-activated receptor 2 (PAR2) signaling controls skin barrier function and inflammation, but the roles of immune cells and PAR2-activating proteases in cutaneous diseases are poorly understood.

OBJECTIVE

To dissect PAR2 signaling contributions to skin inflammation with new genetic and pharmacological tools.

METHODS/RESULTS

We found markedly increased numbers of PAR2+ infiltrating myeloid cells in skin lesions of allergic contact dermatitis (ACD) patients and in the skin of contact hypersensitivity (CHS) in mice, a murine ACD model for T cell-mediated allergic skin inflammation. Cell type-specific deletion of PAR2 in myeloid immune cells as well as mutation-induced complete PAR2 cleavage insensitivity significantly reduced skin inflammation and hapten-specific Tc1/Th1 cell response. Pharmacological approaches identified individual proteases involved in PAR2 cleavage and demonstrated a pivotal role of tissue factor (TF) and coagulation factor Xa (FXa) as upstream activators of PAR2 in both the induction and effector phase of CHS. PAR2 mutant mouse strains with differential cleavage sensitivity for FXa versus skin epithelial cell-expressed proteases furthermore uncovered a time-dependent regulation of CHS development with an important function of FXa-induced PAR2 activation during the late phase of skin inflammation.

CONCLUSIONS

Myeloid cells and the TF-FXa-PAR2 axis are key mediators and potential therapeutic targets in inflammatory skin diseases.

Bafilomycin A1 Accelerates Chronic Refractory Wound Healing in db/db Mice

Numerous studies have reported that autophagy plays an important role in chronic wound healing, and enhancement of autophagic activity impairs cutaneous wound healing. The autophagy inhibitor Bafilomycin A1 (Baf A1) inhibits autophagy by preventing the formation of autophagosomes. This study aimed at elucidating the effect of Bafilomycin A1 on chronic refractory wound healing in diabetic mice. A total of 40 diabetic (db/db) mice and 20 nondiabetic (db/m) mice were used in this study. Full-thickness skin defects were generated in the db/db mice models, which were then divided into the following two groups: the nontreated (db/db group) and Baf A1-treated groups (Baf A1 group). The same skin defects were generated in db/m mice (db/m group) to serve as a control. We demonstrated that Baf A1 treatment significantly accelerated wound healing in db/db mice and exerted good healing effects. Moreover, Baf A1 inhibited autophagy in the newly generated epidermis and had minor effects on metabolism in db/db mice. PCNA expression, as detected by immunohistochemistry, and collagen thickness, as detected by Masson's trichrome staining on the 14th day, were higher in the db/m and Baf A1 groups than in the db/db group. In addition, the expression of the proinflammatory cytokine TNF-α in the db/m and Baf A1 groups increased significantly on day 6, and the expression of the anti-inflammatory cytokine IL-10 also increased significantly on day 9. However, there were no significant changes in the expression levels of TNF-α and IL-10 in the db/db group. Therefore, Baf A1 may accelerate diabetic chronic refractory wound healing by promoting cell proliferation, collagen production, and regulating the inflammatory balance.

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.

MicroRNA-411 and Its 5'-IsomiR Have Distinct Targets and Functions and Are Differentially Regulated in the Vasculature under Ischemia

MicroRNAs are posttranscriptional regulators of gene expression. As microRNAs can target many genes simultaneously, microRNAs can regulate complex multifactorial processes, including post-ischemic neovascularization, a major recovery pathway in cardiovascular disease. MicroRNAs select their target mRNAs via full complementary binding with their seed sequence, i.e., nucleotides 2-8 from the 5' end of a microRNA. The exact sequence of a mature microRNA, and thus of its 5' and 3' ends, is determined by two sequential cleavage steps of microRNA precursors, Drosha/DGCR8 and Dicer. When these cleavage steps result in nucleotide switches at the 5' end, forming a so-called 5'-isomiR, this results in a shift in the mature microRNA's seed sequence. The role of 5'-isomiRs in cardiovascular diseases is still unknown. Here, we characterize the expression and function of the 5'-isomiR of miR-411 (ISO-miR-411). ISO-miR-411 is abundantly expressed in human primary vascular cells. ISO-miR-411 has a different "targetome" from WT-miR-411, with only minor overlap. The ISO-miR-411/WT-miR-411 ratio is downregulated under acute ischemia, both in cells and a murine ischemia model, but is upregulated instead in chronically ischemic human blood vessels. ISO-miR-411 negatively influences vascular cell migration, whereas WT-miR-411 does not. Our data demonstrate that isomiR formation is a functional pathway that is actively regulated during ischemia.

The molecular mechanism study of insulin in promoting wound healing under high-glucose conditions

BACKGROUND

Wound healing is a complex process in bone development. The aim of this study was to explore the molecular mechanism study of insulin in promoting wound healing.

METHODS

Firstly, the acute human monocyte leukemia cell lines were induced to differentiate into macrophages. Secondly, the porphyromonas gingivalis was applied to mix with the differentiated macrophages. Thirdly, the effect of different concentrations of insulin (0 ng/mL, 5 ng/mL, 50 ng/mL, 100 ng/mL, 200 ng/mL, 500 ng/mL, and 1,000 ng/mL) on the phagocytosis of macrophages and production of reactive oxygen species was investigated. Depending on these experiments, the optimal insulin concentration was used to treat the macrophages at different time points (0 hours and 0.5 hours) to identify the differentially expressed mRNAs. Finally, functional analysis including gene ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) and protein-protein interaction (PPI) analysis was carried out to explore the biological function of these differentially expressed mRNAs.

RESULTS

The test of phagocytosis function and production of reactive oxygen species showed that 200 ng/mL insulin treatment had a significant influence on antibacterial and production of reactive oxygen species. In RNA sequencing, a total of 415 (245 upregulated and 170 downregulated) differentially expressed mRNAs were identified between different time points. Two important signaling pathways including endocytosis and systemic lupus erythematosus were found in the KEGG enrichment analysis. In the PPI network, several hub proteins encoded by differentially expressed mRNA including ALB, HIP1R, RAB5A, HIST1H2BJ, HIST1H3G, and HIST1H2BO were identified.

CONCLUSION

Our work demonstrated that several differentially expressed mRNAs, such as EGR1, RAB34, ALB, HIP1R, RAB5A, HIST1H2BJ, HIST1H3G, and HIST1H2BO and two important signaling pathways including endocytosis and systemic lupus erythematosus may play important roles in the bone wound healing.

Contribution of platelets, the coagulation and fibrinolytic systems to cutaneous wound healing

Wound healing is a complex process that consists of multiple phases, each of which are indispensable for adequate repair. Timely initiation and resolution of each of these phases namely, hemostasis, inflammation, proliferation and tissue remodeling, is critical for promoting healing and avoiding excess scar formation. While platelets have long been known to influence the healing process, other components of blood particularly coagulation factors and the fibrinolytic system also contribute to efficient wound repair. This review aims to summarize our current understanding of the role of platelets, the coagulation and fibrinolytic systems in cutaneous wound healing, with a focus on how these components communicate with immune and non-immune cells in the wound microenvironment. We also outline current and potential therapeutic strategies to improve the management of chronic, non-healing wounds.

Virus envelope tissue factor promotes infection in mice

Essentials The coagulation initiator, tissue factor (TF), is on the herpes simplex virus 1 (HSV1) surface. HSV1 surface TF was examined in mice as an antiviral target since it enhances infection in vitro. HSV1 surface TF facilitated infection of all organs evaluated and anticoagulants were antiviral. Protease activated receptor 2 inhibited infection in vivo and its pre-activation was antiviral. SUMMARY: Background Tissue factor (TF) is the essential cell surface initiator of coagulation, and mediates cell signaling through protease-activated receptor (PAR) 2. Having a diverse cellular distribution, TF is involved in many biological pathways and pathologies. Our earlier work identified host cell-derived TF on the envelope covering several viruses, and showed its involvement in enhanced cell infection in vitro. Objective In the current study, we evaluated the in vivo effects of virus surface TF on infection and on the related modulator of infection PAR2. Methods With the use of herpes simplex virus type 1 (HSV1) as a model enveloped virus, purified HSV1 was generated with or without envelope TF through propagation in a TF-inducible cell line. Infection was studied after intravenous inoculation of BALB/c, C57BL/6J or C57BL/6J PAR2 knockout mice with 5 × 105 plaque-forming units of HSV1, mimicking viremia. Three days after inoculation, organs were processed, and virus was quantified with plaque-forming assays and quantitative real-time PCR. Results Infection of brain, lung, heart, spinal cord and liver by HSV1 required viral TF. Demonstrating promise as a therapeutic target, virus-specific anti-TF mAbs or small-molecule inhibitors of coagulation inhibited infection. PAR2 modulates HSV1 in vivo as demonstrated with PAR2 knockout mice and PAR2 agonist peptide. Conclusion TF is a constituent of many permissive host cell types. Therefore, the results presented here may explain why many viruses are correlated with hemostatic abnormalities, and indicate that TF is a novel pan-specific envelope antiviral target.

Platelet glycoprotein VI and C-type lectin-like receptor 2 deficiency accelerates wound healing by impairing vascular integrity in mice

Platelets promote wound healing by forming a vascular plug and by secreting growth factors and cytokines. Glycoprotein (GP)VI and C-type lectin-like receptor (CLEC)-2 signal through a (hem)-immunoreceptor tyrosine-based activation motif, which induces platelet activation. GPVI and CLEC-2 support vascular integrity during inflammation in the skin through regulation of leukocyte migration and function, and by sealing sites of vascular damage. In this study, we investigated the role of impaired vascular integrity due to GPVI and/or CLEC-2 deficiency in wound repair using a full-thickness excisional skin wound model in mice. Transgenic mice deficient in both GPVI and CLEC-2 exhibited accelerated skin wound healing, despite a marked impairment in vascular integrity. The local and temporal bleeding in the skin led to greater plasma protein entry, including fibrinogen and clotting factors, was associated with increased fibrin generation, reduction in wound neutrophils and M1 macrophages, decreased level of tumor necrosis factor (TNF)-α, and enhanced angiogenesis at day 3 after injury. Accelerated wound healing was not due to developmental defects in CLEC-2 and GPVI double-deficient mice as similar results were observed in GPVI-deficient mice treated with a podoplanin-blocking antibody. The rate of wound healing was not altered in mice deficient in either GPVI or CLEC-2. Our results show that, contrary to defects in coagulation, bleeding following a loss of vascular integrity caused by platelet CLEC-2 and GPVI deficiency facilitates wound repair by increasing fibrin(ogen) deposition, reducing inflammation, and promoting angiogenesis.

Innate immunity, hemostasis and matrix remodeling: PTX3 as a link

Innate immunity is evolutionarily connected with hemostasis. PTX3 is an essential fluid-phase pattern recognition molecule of the innate immune system that acts as a functional ancestor of antibodies. PTX3 by interacting with defense collagens and fibrinogens amplifies effector functions of the innate immune system. At wound sites, PTX3 regulates the injury-induced thrombotic response and promotes wound healing by favoring timely fibrinolysis. Therefore, PTX3 interacts with ancestral domains conserved in innate immunity, hemostasis and extracellular matrix and exerts functions related to both antimicrobial resistance and tissue repair. These findings strengthen the connection between innate immune system and hemostasis, and suggest that recognition of microbes and extracellular matrix are evolutionarily conserved and integrated functions of the innate immune system.

AGEs Induced Autophagy Impairs Cutaneous Wound Healing via Stimulating Macrophage Polarization to M1 in Diabetes

Autophagy is essential in physiological and pathological processes, however, the role of autophagy in cutaneous wound healing and the underlying molecular mechanism remain elusive. We hypothesized that autophagy plays an important role in regulating wound healing. Here, we show that enhanced autophagy negatively impacts on normal cutaneous healing process and is related to chronic wounds as demonstrated by the increased LC3 in diabetic mice skin or patients' chronic wounds. In addition, inhibition of autophagy by 3-MA restores delayed healing in C57BL/6 or db/db mice, demonstrating that autophagy is involved in regulating wound healing. Furthermore, we identify that macrophage is a major cell type underwent autophagy in wounds and increased autophagy induces macrophages polarization into M1 with elevated CD11c population and gene expressions of proinflammatory cytokines. To explore the mechanism underlying autophagy-impaired wound healing, we tested the role of IRF8, a regulator of autophagy, in autophagy-modulated macrophages polarization. IRF8 activation is up-regulating autophagy and M1 polarization of macrophages after AGEs (advanced glycation endproducts) treatment, blocking the IRF8 with shIRF8 inhibits autophagic activity and M1 polarization. In summary, this study elucidates that AGEs induces autophagy and modulates macrophage polarization to M1 via IRF8 activation in impairment of cutaneous wound healing.

Transition from inflammation to proliferation: a critical step during wound healing

The ability to rapidly restore the integrity of a broken skin barrier is critical and is the ultimate goal of therapies for hard-to-heal-ulcers. Unfortunately effective treatments to enhance healing and reduce scarring are still lacking. A deeper understanding of the physiology of normal repair and of the pathology of delayed healing is a prerequisite for the development of more effective therapeutic interventions. Transition from the inflammatory to the proliferative phase is a key step during healing and accumulating evidence associates a compromised transition with wound healing disorders. Thus, targeting factors that impact this phase transition may offer a rationale for therapeutic development. This review summarizes mechanisms regulating the inflammation-proliferation transition at cellular and molecular levels. We propose that identification of such mechanisms will reveal promising targets for development of more effective therapies.

Role of the protein C receptor in cancer progression

The hemostatic system plays pleiotropic roles in cancer progression by shaping the tumor microenvironment and metastatic niches through thrombin-dependent fibrin deposition and platelet activation. Expanding experimental evidence implicates coagulation protease receptors expressed by tumor cells as additional players that directly influence tumor biology. Pro-angiogenic G protein-coupled signaling of TF through protease activated receptor 2 and regulation of tumor cell and vascular integrins through ligation by alternative spliced TF are established pathways driving tumor progression. Our recent work shows that the endothelial protein C receptor (EPCR), a stem cell marker in hematopoietic, neuronal and epithelial cells, is also crucial for breast cancer growth in the orthotopic microenvironment of the mammary gland. In aggressive triple-negative breast cancer cells, EPCR expression is a characteristic of cancer stem cell-like populations that have tumor initiating properties in vivo. Blocking antibodies to EPCR attenuate in vivo tumor growth and proliferation specifically of EPCR(+) cells on defined integrin matrices in vitro. We also showed that tumor-associated macrophages are a source for upstream coagulation proteases that can activate TF- and EPCR-dependent cellular responses, suggesting that tumor cells utilize the tumor microenvironment for tumor promoting coagulation protease signaling.

Tissue factor-integrin interactions in cancer and thrombosis: every Jack has his Jill

Tissue factor (TF) is a 47 kDa membrane protein that initiates coagulation by binding to FVII(a) and FX(a) and is a risk factor for thrombosis in many disease states. In addition to its coagulant activity, TF also influences cancer progression by triggering signaling effects via a group of G-protein coupled receptors named protease-activated receptors (PARs). TF localizes to cytoskeletal structures in migrating cells, influences cytoskeleton reorganization and promotes migration. Recently, integrins, important mediators of cell motility, have emerged as important binding partners for TF and influence both TF coagulant and PAR-2-dependent signaling functions. Direct binding of TF to integrins also impacts processes such as cell migration and signaling independent of PAR-2. A recently discovered alternatively spliced, soluble TF isoform also ligates integrins to augment angiogenesis, thus fuelling cancer progression. To date, the literature describes a complex interplay between different integrin subunits and distinct TF isoforms, but our understanding of TF-integrin bidirectional regulation remains clouded. In this review, we aim to summarize the existing knowledge on integrin-TF interaction and speculate on its relevance to physiology and pathology.

Upregulation of the coagulation factor VII gene during glucose deprivation is mediated by activating transcription factor 4

Background

Constitutive production of blood coagulation proteins by hepatocytes is necessary for hemostasis. Stressful conditions trigger adaptive cellular responses and delay processing of most proteins, potentially affecting plasma levels of proteins secreted exclusively by hepatocytes. We examined the effect of glucose deprivation on expression of coagulation proteins by the human hepatoma cell line, HepG2.

Methodology/Principal Findings

Expression of coagulation factor VII, which is required for initiation of blood coagulation, was elevated by glucose deprivation, while expression of other coagulation proteins decreased. Realtime PCR and ELISA demonstrated that the relative percentage expression +/− SD of steady-state F7 mRNA and secreted factor VII antigen were significantly increased (from 100+/−15% to 188+/−27% and 100+/−8.8% to 176.3+/−17.3% respectively, p<0.001) at 24 hr of treatment. The integrated stress response was induced, as indicated by upregulation of transcription factor ATF4 and of additional stress-responsive genes. Small interfering RNAs directed against ATF4 potently reduced basal F7 expression, and prevented F7 upregulation by glucose deprivation. The response of the endogenous F7 gene was replicated in reporter gene assays, which further indicated that ATF4 effects were mediated via interaction with an amino acid response element in the F7 promoter.

Conclusions/Significance

Our data indicated that glucose deprivation enhanced F7 expression in a mechanism reliant on prior ATF4 upregulation primarily due to increased transcription from the ATF4 gene. Of five coagulation protein genes examined, only F7 was upregulated, suggesting that its functions may be important in a systemic response to glucose deprivation stress.

Protease-activated receptor 2 signaling in inflammation

Protease-activated receptors (PARs) are G protein-coupled receptors that are activated by proteolytical cleavage of the amino-terminus and thereby act as sensors for extracellular proteases. While coagulation proteases activate PARs to regulate hemostasis, thrombosis, and cardiovascular function, PAR2 is also activated in extravascular locations by a broad array of serine proteases, including trypsin, tissue kallikreins, coagulation factors VIIa and Xa, mast cell tryptase, and transmembrane serine proteases. Administration of PAR2-specific agonistic and antagonistic peptides, as well as studies in PAR2 knockout mice, identified critical functions of PAR2 in development, inflammation, immunity, and angiogenesis. Here, we review these roles of PAR2 with an emphasis on the role of coagulation and other extracellular protease pathways that cleave PAR2 in epithelial, immune, and neuronal cells to regulate physiological and pathophysiological processes.

Tissue factor, blood coagulation, and beyond: an overview

Emerging evidence shows a broad spectrum of biological functions of tissue factor (TF). TF classical role in initiating the extrinsic blood coagulation and its direct thrombotic action in close relation to cardiovascular risks have long been established. TF overexpression/hypercoagulability often observed in many clinical conditions certainly expands its role in proinflammation, diabetes, obesity, cardiovascular diseases, angiogenesis, tumor metastasis, wound repairs, embryonic development, cell adhesion/migration, innate immunity, infection, pregnancy loss, and many others. This paper broadly covers seminal observations to discuss TF pathogenic roles in relation to diverse disease development or manifestation. Biochemically, extracellular TF signaling interfaced through protease-activated receptors (PARs) elicits cellular activation and inflammatory responses. TF diverse biological roles are associated with either coagulation-dependent or noncoagulation-mediated actions. Apparently, TF hypercoagulability refuels a coagulation-inflammation-thrombosis circuit in “autocrine” or “paracrine” fashions, which triggers a wide spectrum of pathophysiology. Accordingly, TF suppression, anticoagulation, PAR blockade, or general anti-inflammation offers an array of therapeutical benefits for easing diverse pathological conditions.