Bioactivity of the vascular endothelial growth factor trapped in fibrin clots: production of IL-6 and IL-8 in monocytes by fibrin clots

Sustained and intermittent hypoxia differentially modulate primary monocyte immunothrombotic responses to IL-1β stimulation

Venous thromboembolism (VTE) is a leading cause of preventable deaths in hospitals, and its incidence is not decreasing despite extensive efforts in clinical and laboratory research. Venous thrombi are primarily formed in the valve pockets of deep veins, where activated monocytes play a crucial role in bridging innate immune activation and hemostatic pathways through the production of inflammatory cytokines, chemokines, and tissue factor (TF) - a principal initiator of coagulation. In the valve pocket inflammation and hypoxia (sustained/intermittent) coexist, however their combined effects on immunothrombotic processes are poorly understood. Inflammation is strongly associated with VTE, while the additional contribution of hypoxia remains largely unexplored. To investigate this, we modelled the intricate conditions of the venous valve pocket using a state-of-the-art hypoxia chamber with software-controlled oxygen cycling. We comprehensively studied the effects of sustained and intermittent hypoxia alone, and in combination with VTE-associated inflammatory stimuli on primary monocytes. TF expression and activity was measured in monocytes subjected to sustained and intermittent hypoxia alone, or in combination with IL-1β. Monocyte responses were further analyzed in detailed by RNA sequencing and validated by ELISA. Stimulation with IL-1β alone promoted both transcription and activity of TF. Interestingly, the stimulatory effect of IL-1β on TF was attenuated by sustained hypoxia, but not by intermittent hypoxia. Our transcriptome analysis further confirmed that sustained hypoxia limited the pro-inflammatory response induced by IL-1β, and triggered a metabolic shift in monocytes. Intermittent hypoxia alone had a modest effect on monocyte transcript. However, in combination with IL-1β intermittent hypoxia significantly altered the expression of 2207 genes and enhanced the IL-1β-stimulatory effects on several chemokine and interleukin genes (e.g., IL-19, IL-24, IL-32, MIF), as well as genes involved in coagulation (thrombomodulin) and fibrinolysis (VEGFA, MMP9, MMP14 and PAI-1). Increased production of CCL2, IL-6 and TNF following stimulation with intermittent hypoxia and IL-1β was confirmed by ELISA. Our findings provide valuable insights into how the different hypoxic profiles shape the immunothrombotic response of monocytes and shed new light on the early events in the pathogenesis of venous thrombosis.

A Novel Volume-Stable Collagen Matrix Induces Changes in the Behavior of Primary Human Oral Fibroblasts, Periodontal Ligament, and Endothelial Cells

The aim of the present study was to investigate the influence of a novel volume-stable collagen matrix (vCM) on early wound healing events including cellular migration and adhesion, protein adsorption and release, and the dynamics of the hemostatic system. For this purpose, we utilized transwell migration and crystal violet adhesion assays, ELISAs for quantification of adsorbed and released from the matrix growth factors, and qRT-PCR for quantification of gene expression in cells grown on the matrix. Our results demonstrated that primary human oral fibroblasts, periodontal ligament, and endothelial cells exhibited increased migration toward vCM compared to control cells that migrated in the absence of the matrix. Cellular adhesive properties on vCM were significantly increased compared to controls. Growth factors TGF-β1, PDGF-BB, FGF-2, and GDF-5 were adsorbed on vCM with great efficiency and continuously delivered in the medium after an initial burst release within hours. We observed statistically significant upregulation of genes encoding the antifibrinolytic thrombomodulin, plasminogen activator inhibitor type 1, thrombospondin 1, and thromboplastin, as well as strong downregulation of genes encoding the profibrinolytic tissue plasminogen activator, urokinase-type plasminogen activator, its receptor, and the matrix metalloproteinase 14 in cells grown on vCM. As a general trend, the stimulatory effect of the vCM on the expression of antifibrinolytic genes was synergistically enhanced by TGF-β1, PDGF-BB, or FGF-2, whereas the strong inhibitory effect of the vCM on the expression of profibrinolytic genes was reversed by PDGF-BB, FGF-2, or GDF-5. Taken together, our data strongly support the effect of the novel vCM on fibrin clot stabilization and coagulation/fibrinolysis equilibrium, thus facilitating progression to the next stages of the soft tissue healing process.

Sparganin A alleviates blood stasis syndrome and its key targets by molecular docking

Blood stasis syndrome is implicated in the development of chronic conditions, including cardio- and cerebrovascular diseases. Cyclo-(Tyr-Leu), named Sparganin A (SA), is a compound isolated from the ethanol extract of Rhizoma Sparganii. Here, the successful extraction of SA from Rhizoma Sparganii was verified by extensive spectral analysis using 1H NMR and 13C NMR. To determine the biological effects of SA, a mouse model of acute blood stasis was established by subcutaneous injection of adrenaline hydrochloride and placing the animals in an ice water bath. In this model, the concentration of TXB2, PAI-1, FIB, ET-1 was measured by ELISA, and thymus index (TI), hepatic index (HI), and spleen index (SI) were calculated. Molecular docking by SYBYL and functional analysis of the putative targets by STRING and Cytoscape were employed to identify the key targets of SA. The accumulated results documented that SA exhibits anticoagulative activity, and its key targets are VEGFA and SERPINE1. SA may be involved in the pathological process of complement and coagulation cascades. This study demonstrates that SA may be a promising drug to control coagulation in blood stasis syndrome.

Alveolar blood clots and platelet-rich fibrin induce in vitro fibroblast proliferation and migration

Wound healing process comprises a complex network of cells and molecules that are regulated in order to pursue tissue regeneration. Our study focused on the capacity of alveolar blood clots (ABCs), platelet-rich fibrin (PRF) and plasma rich in growth factors (PRGF) to induce in vitro fibroblasts proliferation and migration as a measure of alveolar regeneration. Using cellular impedance with xCELLigence technology we quantified the proliferation and the migration capacity of L929 fibroblast standard cell line in the presence of 4 different ABCs and 3 different PRFs harvested from healthy individuals during standard tooth extraction. We obtained a clear cellular proliferation induced by the compounds mainly after 24 h of cultivation, in a dose-dependent manner. After 48 h of cultivation we registered activated proliferation, but slightly decreased compared to the 24 h profile. Our data confirm that the presence of the blood clot is involved in the regenerative processes. The migratory capacity of fibroblasts was statistically activated by the PL compounds while not affected by the tested PRFs. The chemical mediators present within the blood clot, either produced by inflammatory cells captive within, or by endothelial or mesenchymal cells induced fibroblastic proliferation and subsequent collagen deposition.

Regulatory role of miRNA-26a in neonatal sepsis

The present study aimed to investigate the expression of microRNA (miRNA) 26a in blood mononuclear cells and serum in neonatal sepsis, as well as its role in the disease pathogenesis. In total 28 cases of neonatal sepsis were included in the study. The mRNA expression levels of miRNA-26a and interleukin (IL)-6 in the blood mononuclear cells and serum samples were detected by reverse transcription-quantitative polymerase chain reaction. The protein expression of IL-6 was detected by western blot analysis and ELISA. The in vitro septic environment was simulated by lipopolysaccharide (LPS) in THP-1 cells, and the expression of miRNA-26a and IL-6 were determined. Interaction between miRNA-26a and IL-6 was confirmed by a dual-luciferase reporter assay. Compared with the control group, the mRNA and protein expression levels of IL-6 in the blood mononuclear cells and serum samples from the neonates with sepsis were significantly elevated, while the expression of miRNA-26a was significantly decreased. In addition, similar results were observed in the LPS-induced septic models in THP-1 cells. Furthermore, the results of the dual-luciferase reporter assay demonstrated that IL-6 was the direct target of miRNA-26a. The expression of IL-6 was significantly upregulated in the blood mononuclear cells and serum in neonatal sepsis, which may be associated with the downregulation of miRNA-26a. miRNA-26a may regulate the disease pathogenesis and immune responses.

MicroRNA-365 regulates the occurrence and immune response of sepsis following multiple trauma via interleukin-6

In the present study, the expression of microRNA (miR)-365 and interleukin (IL)-6 in peripheral blood mononuclear cells and serum from patients with sepsis following multiple trauma has been investigated. A total of 26 patients with sepsis following multiple trauma were included as the experimental group, whereas 21 contemporaneous patients without sepsis following multiple trauma were included as the negative control group. The expression of IL-6 mRNA and miR-365 was determined by reverse transcription-quantitative polymerase chain reaction, and western blot analysis was used to measure IL-6 protein expression. ELISA was performed to determine the secretion of IL-6 protein. Following stimulation with lipopolysaccharide (LPS) for 24 h, THP-1 cells were used to examine the expression of miR-365 and the levels of IL-6 protein and mRNA in cells simulating sepsis. A dual luciferase reporter assay revealed that IL-6 mRNA was a direct target of miR-365. Patients with sepsis following multiple trauma exhibited significantly higher IL-6 mRNA and protein levels than patients without sepsis (P<0.05). In addition, miR-365 expression in patients with sepsis following trauma was significantly lower than in patients without sepsis (P<0.05). Similar effects were observed in THP-1 cells treated with LPS. The present study demonstrated that increased expression of IL-6 in patients with sepsis following multiple trauma is associated with decreased expression of miR-365. miR-365 may regulate the occurrence and immune response of sepsis following multiple trauma via IL-6. These results may elucidate agents for clinical diagnosis and treatment of the disease.

Lung injury caused by paraquat poisoning results in increased interleukin-6 and decreased microRNA-146a levels

The aim of the present study was to investigate the expression of microRNA (miR)-146a in the pulmonary macrophages, peripheral blood mononuclear cells and serum of patients with lung injury caused by paraquat poisoning, as well as the underlying mechanism of its regulation in the disease. A total of 26 patients with lung injury caused by paraquat poisoning were included in the present study. In addition, 33 healthy subjects were included as the control group. The expression levels of interleukin (IL)-6 mRNA and miR-146a was determined by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Western blotting was used to measure IL-6 protein expression, while enzyme-linked immunosorbent assay was also performed to determine the secretion of IL-6 protein. A dual-luciferase reporter assay was conducted to examine whether IL-6 mRNA is a direct target of miR-146a. Patients with lung injury caused by paraquat poisoning exhibited higher IL-6 mRNA and protein levels as compared with those in healthy subjects. In addition, miR-146a expression in patients with paraquat poisoning-induced lung injury was significantly reduced in comparison with that in healthy subjects. Notably, the overexpression of miR-146a by mimic transfection downregulated the expression of IL-6 in pulmonary macrophages. The results of dual-luciferase reporter assay demonstrated that IL-6 mRNA was a direct target of miR-146a. Therefore, the present study demonstrated that increased expression of IL-6 in patients with lung injury caused by paraquat poisoning is associated with decreased expression of miR-146a. Furthermore, miR-146a may regulate the occurrence and immune response of lung injury caused by paraquat poisoning and this process is possibly achieved via IL-6, an important cytokine that mediates inflammation.

Clots Are Potent Triggers of Inflammatory Cell Gene Expression: Indications for Timely Fibrinolysis

OBJECTIVE

Blood vessel wall damage often results in the formation of a fibrin clot that traps inflammatory cells, including monocytes. The effect of clot formation and subsequent lysis on the expression of monocyte-derived genes involved in the development and progression of ischemic stroke and other vascular diseases, however, is unknown. Determine whether clot formation and lysis regulates the expression of human monocyte-derived genes that modulate vascular diseases.

APPROACH AND RESULTS

We performed next-generation RNA sequencing on monocytes extracted from whole blood clots and using a purified plasma clot system. Numerous mRNAs were differentially expressed by monocytes embedded in clots compared with unclotted controls, and IL-8 (interleukin 8) and MCP-1 (monocyte chemoattractant protein-1) were among the upregulated transcripts in both models. Clotted plasma also increased expression of IL-8 and MCP-1, which far exceeded responses observed in lipopolysaccharide-stimulated monocytes. Upregulation of IL-8 and MCP-1 occurred in a thrombin-independent but fibrin-dependent manner. Fibrinolysis initiated shortly after plasma clot formation (ie, 1-2 hours) reduced the synthesis of IL-8 and MCP-1, whereas delayed fibrinolysis was far less effective. Consistent with these in vitro models, monocytes embedded in unresolved thrombi from patients undergoing thrombectomy stained positively for IL-8 and MCP-1.

CONCLUSIONS

These findings demonstrate that clots are potent inducers of monocyte gene expression and that timely fibrinolysis attenuates inflammatory responses, specifically IL-8 and MCP-1. Dampening of inflammatory gene expression by timely clot lysis may contribute to the clinically proven efficacy of fibrinolytic drug treatment within hours of stroke onset.

An unexpected tail of VEGF and PlGF in pre-eclampsia

PET (pre-eclamptic toxaemia), characterized by pregnancy-related hypertension and proteinuria, due to widespread endothelial dysfunction, is a primary cause of maternal morbidity. Altered circulating factors, particularly the VEGF (vascular endothelial growth factor) family of proteins and their receptors, are thought to be key contributors to this disease. Plasma from patients with PET induces numerous cellular and physiological changes in endothelial cells, indicating the presence of a circulating imbalance of the normal plasma constituents. These have been narrowed down to macromolecules of the VEGF family of proteins and receptors. It has been shown that responses of endothelial cells in intact vessels to plasma from patients with pre-eclampsia is VEGF-dependent. It has recently been shown that this may be specific to the VEGF₁₆₅b isoform, and blocked by addition of recombinant human PlGF (placental growth factor). Taken together with results that show that sVEGFR1 (soluble VEGF receptor 1) levels are insufficient to bind VEGF-A in human plasma from patients with pre-eclampsia, and that other circulating macromolecules bind, but do not inactivate, VEGF-A, this suggests that novel hypotheses involving altered bioavailability of VEGF isoforms resulting from reduced or bound PlGF, or increased sVEGFR1 increasing biological activity of circulating plasma, could be tested. This suggests that knowing how to alter the balance of VEGF family members could prevent endothelial activation, and potentially some symptoms, of pre-eclampsia.

Stem cell applications in tendon disorders: a clinical perspective

Tendon injuries are a common cause of morbidity and a significant health burden on society. Tendons are structural tissues connecting muscle to bone and are prone to tearing and tendinopathy, an overuse or degenerative condition that is characterized by failed healing and cellular depletion. Current treatments, for tendon tear are conservative, surgical repair or surgical scaffold reconstruction. Tendinopathy is treated by exercises, injection therapies, shock wave treatments or surgical tendon debridement. However, tendons usually heal with fibrosis and scar tissue, which has suboptimal tensile strength and is prone to reinjury, resulting in lifestyle changes with activity restriction. Preclinical studies show that cell therapies have the potential to regenerate rather than repair tendon tissue, a process termed tenogenesis. A number of different cell lines, with varying degrees of differentiation, have being evaluated including stem cells, tendon derived cells and dermal fibroblasts. Even though cellular therapies offer some potential in treating tendon disorders, there have been few published clinical trials to determine the ideal cell source, the number of cells to administer, or the optimal bioscaffold for clinical use.

Blood components for topical use in tissue regeneration: evaluation of corneal lesions treated with platelet lysate and considerations on repair mechanisms

BACKGROUND

The fields of application of topically administered platelet derivatives are numerous and increasing. The use of this blood component is based on the fact that it contains growth factors and proteins of the clotting system. Studies carried out so far have been aimed at identifying these substances, assaying their content in the various types of platelet concentrate used, determining the in vivo and in vitro mechanisms of action, and trying to standardise the production methods. However, much still remains to be discovered, not only about the growth factors, but also about all those cytokines and biochemical mediators that are involved in the processes of tissue regeneration.

METHODS

We studied the use of platelet lysate, obtained from platelet-rich plasma which had been frozen, for the treatment of corneal ulcers caused by neurotrophic keratitis and of epithelial and stromal loss following physical or chemical trauma. The platelet lysate was administered in the form of eye drops to patients who had not responded to conventional therapy and who were at risk of corneal scarring.

RESULTS

The results were satisfactory in terms of both tissue regeneration and healing time. The clinical follow-up showed a clear reduction in the time of regeneration of the damaged epithelium and stabilisation of the repair process. The epithelial defects disappeared completely in all the treated eyes within 6 to 32 days, with the time depending on the type of lesion and the severity of the damage.

CONCLUSIONS

The cornea reacts to damage by releasing numerous substances, including cytokines, growth factors, proteases and neuropeptides in order to restore its anatomical integrity. A change in the balance between inhibitory and stimulating substances can lead to the development of complications. Fast, correct re-epithelialisation is fundamental for the formation of new, transparent tissue. The use of non-gelified platelet-rich plasma was found to be effective in all cases with loss of epithelium, such as post-herpetic corneal ulcers or ulcers occurring following trauma or exposure to caustic substances.

A reference database for tumor-related genes co-expressed with interleukin-8 using genome-scale in silico analysis

BACKGROUND

The EST database provides a rich resource for gene discovery and in silico expression analysis. We report a novel computational approach to identify co-expressed genes using EST database, and its application to IL-8.

RESULTS

IL-8 is represented in 53 dbEST cDNA libraries. We calculated the frequency of occurrence of all the genes represented in these cDNA libraries, and ranked the candidates based on a Z-score. Additional analysis suggests that most IL-8 related genes are differentially expressed between non-tumor and tumor tissues. To focus on IL-8's function in tumor tissues, we further analyzed and ranked the genes in 16 IL-8 related tumor libraries.

CONCLUSIONS

This method generated a reference database for genes co-expressed with IL-8 and could facilitate further characterization of functional association among genes.