IL-8 induces imbalances between nitric oxide and endothelin-1, and also between plasminogen activator inhibitor-1 and tissue-type plasminogen activator in cultured endothelial cells

Platelet Content from Acute Myocardial Infarction Patients: Elevated Levels of IL-6 and IL-8 and their impact on Endothelial Nitric Oxide Production

BACKGROUND AND AIMS

Platelets and inflammation play crucial roles in the atherothrombotic process of acute myocardial infarction (AMI), particularly in ischemia/reperfusion injury. This study aims to characterize the pro-inflammatory content of the platelet secretome in AMI patients, assess its effect on nitric oxide (NO) production, and correlate these findings with clinical parameters.

METHODS

Blood samples from 20 AMI patients and 20 controls were analyzed. Platelets were isolated and stimulated with thrombin, and their secretomes were collected. Endothelial cells were exposed to these secretomes, and NO production was measured. Our results demonstrate a significant reduction in NO production in endothelial cells exposed to the AMI platelet secretome (p < 0.05), suggesting acute endothelial dysfunction.

RESULTS

Elevated levels of interleukin-6 (IL-6) (p = 0.0323) and interleukin-8 (IL-8) (p = 0.0197) were identified in the secretome of AMI patients, correlating with clinical markers of myocardial injury. Specifically, IL-6 positively correlated with CK-MB levels (p = 0.04, Pearson r = 0.53), while IL-8 levels inversely correlated with NO production (p = 0.0141, Pearson r = -0.5652).

CONCLUSIONS

These findings underscore the critical role of platelet-derived IL-6 and IL-8 in endothelial dysfunction and myocardial injury in AMI patients. Future studies should explore the interactions between these cytokines in endothelial cells to further elucidate their roles in AMI pathology.

Predictive Value of Selected Plasma Biomarkers in the Assessment of the Occurrence and Severity of Coronary Artery Disease

Despite significant advances in imaging modalities for diagnosing coronary artery disease (CAD), there remains a need for novel diagnostic approaches with high predictive values and fewer limitations. Circulating biomarkers, including cytokines such as interleukin-6 (IL-6) and interleukin-8 (IL-8), cell adhesion molecules such as soluble vascular cell adhesion molecule-1 (sVCAM-1), peptides secreted by endothelial cells such as endothelin-1 (ET-1), and enzymes involved in extracellular matrix remodeling such as a disintegrin and metalloproteinase with thrombospondin motifs-1 (ADAMTS-1) offer a promising alternative. This study aimed to evaluate the correlation between the plasma levels of selected biomarkers and the presence and severity of CAD. We enrolled 40 patients admitted for elective coronary angiography. CAD was defined as having at least one coronary artery stenosis ≥ 50%. The severity of CAD was assessed using the Gensini Score (GS). IL-8 levels were significantly higher in the CAD group, with a mean of 9.78 (SD 0.46) compared to 8.37 (SD 0.40) in the non-CAD group (p = 0.0228). No significant differences were observed for the other biomarkers between the groups. A positive Spearman correlation was found between IL-8 levels and the GS (ρ = 0.39, p = 0.017). These findings suggest that IL-8 may have potential as an additional tool for diagnosing or excluding atherosclerosis. Further studies with larger sample sizes are needed to validate its clinical utility.

Trained innate immunity as a potential link between preeclampsia and future cardiovascular disease

Preeclampsia (PE) is a complex pregnancy syndrome characterized by hypertension with or without proteinuria, affecting 2-6% of pregnancies globally. PE is characterized by excessive release of damage-associated molecular patterns (DAMPs) into the maternal circulation. This DAMP-rich milieu acts on innate immune cells, inducing a proinflammatory state characterized by elevated cytokines such as IL-1β and IL-18. This proinflammatory state in the mother and placenta results in the endothelial dysfunction strongly associated with cardiovascular disorders. While the immediate maternal and fetal risks of PE are well-documented, accumulating evidence indicates that PE also confers long-term cardiovascular risks to the mother, including hypertension, coronary heart disease, stroke, and heart failure. The underlying mechanisms connecting PE to these chronic cardiovascular conditions remain unclear. This article explores the potential role of trained innate immunity (TRIM) as a mechanistic link between PE and increased long-term cardiovascular risk. We propose that the persistent exposure to DAMPs during PE may epigenetically reprogram maternal innate immune cells and their progenitors, leading to TRIM. This reprogramming enhances the inflammatory response to subsequent stimuli, potentially contributing to endothelial dysfunction and chronic inflammation that predispose women to cardiovascular diseases later in life. Understanding the role of TRIM in PE could provide novel insights into the pathophysiology of PE-related cardiovascular complications and identify potential targets for therapeutic intervention. Further research is warranted to investigate the epigenetic and metabolic alterations in innate immune cells induced by PE and to determine how these changes may influence long-term maternal cardiovascular health.

The suboptimal fibrinolytic response in COVID-19 is dictated by high PAI-1

BACKGROUND

Severe COVID-19 disease is associated with thrombotic complications and extensive fibrin deposition. This study investigates whether the hemostatic complications in COVID-19 disease arise due to dysregulation of the fibrinolytic system.

METHODS

This prospective study analyzed fibrinolytic profiles of 113 patients hospitalized with COVID-19 disease with 24 patients with non-COVID-19 respiratory infection and healthy controls. Antigens were quantified by Ella system or ELISA, clot lysis by turbidimetric assay, and plasminogen activator inhibitor-1 (PAI-1)/plasmin activity using chromogenic substrates. Clot structure was visualized by confocal microscopy.

RESULTS

PAI-1 and its cofactor, vitronectin, are significantly elevated in patients with COVID-19 disease compared with those with non-COVID-19 respiratory infection and healthy control groups. Thrombin activatable fibrinolysis inhibitor and tissue plasminogen activator were elevated in patients with COVID-19 disease relative to healthy controls. PAI-1 and tissue plasminogen activator (tPA) were associated with more severe COVID-19 disease severity. Clots formed from COVID-19 plasma demonstrate an altered fibrin network, with attenuated fiber length and increased branching. Functional studies reveal that plasmin generation and clot lysis were markedly attenuated in COVID-19 disease, while PAI-1 activity was elevated. Clot lysis time significantly correlated with PAI-1 levels. Stratification of COVID-19 samples according to PAI-1 levels reveals significantly faster lysis when using the PAI-1 resistant (tPA) variant, tenecteplase, over alteplase lysis.

CONCLUSION

This study shows that the suboptimal fibrinolytic response in COVID-19 disease is directly attributable to elevated levels of PAI-1, which attenuate plasmin generation. These data highlight the important prognostic potential of PAI-1 and the possibility of using pre-existing drugs, such as tenecteplase, to treat COVID-19 disease and potentially other respiratory diseases.

The Role of Chemokines in Cardiovascular Diseases and the Therapeutic Effect of Curcumin on CXCL8 and CCL2 as Pathological Chemokines in Atherosclerosis

Curcumin, as a vegetative flavonoid, has a protective and therapeutic role in various adverse states such as oxidative stress and inflammation. Remedial properties of this component have been reported in the different chronic diseases including cancers (myeloma, pancreatic, breast, colorectal), vitiligo, psoriasis, neuropathic pains, inflammatory disorders (osteoarthritis, uveitis, ulcerative colitis, Alzheimer), cardiovascular conditions, and diabetes.Cardiovascular disorders include atherosclerosis and various manifestations of atherosclerosis such as stroke, and myocardial infarction (MI) is the leading cause of mortality globally. Studies have shown varying expressions of inflammatory and non-inflammatory chemokines and chemokine receptors in cardiovascular disease, which have been highlighted first in this review. The alteration in chemokines secretion and chemokine receptors has an essential role in the pathophysiology of cardiovascular disease. Chemokines as cytokines with low molecular weight (8-12 kDa) mediate white blood cell (WBC) chemotactic reactions, vascular cell migration, and proliferation that induce endothelial dysfunction, atherogenesis, and cardiac hypertrophy.Several studies reported that curcumin could be advantageous in the attenuation of cardiovascular diseases via anti-inflammatory effects and redress of chemokine secretion and chemokine receptors. We present these studies with a focus on two chemokines: CXCL8 (IL-8) and CCL2 (chemoattractant protein 1 or MCP-1). Future research will further elucidate the precise potential of curcumin on chemokines in the adjustment of cardiovascular system activity or curcumin chemokine-based therapies.

Correlating Fibrinogen Consumption and Profiles of Inflammatory Molecules in Human Envenomation's by Bothrops atrox in the Brazilian Amazon

Snakebites are considered a major public health problem worldwide. In the Amazon region of Brazil, the snake Bothrops atrox (B. atrox) is responsible for 90% of the bites. These bites may cause local and systemic signs from acute inflammatory reaction and hemostatic changes, and present common hemorrhagic disorders. These alterations occur due the action of hemostatically active and immunogenic toxins which are capable of triggering a wide range of hemostatic and inflammatory events. However, the crosstalk between coagulation disorders and inflammatory reaction still has gaps in snakebites. Thus, the goal of this study was to describe the relationship between the consumption of fibrinogen and the profile of inflammatory molecules (chemokines and cytokines) in evenomations by B. atrox snakebites. A prospective study was carried out with individuals who had suffered B. atrox snakebites and presented different levels of fibrinogen consumption (normal fibrinogen [NF] and hypofibrinogenemia [HF]). Seventeen patients with NF and 55 patients with HF were eligible for the study, in addition to 50 healthy controls (CG). The molecules CXCL-8, CCL-5, CXCL-9, CCL-2, CXCL-10, IL-6, TNF, IL-2, IL-10, IFN-γ, IL-4, and IL-17A were quantified in plasma using the CBA technique at three different times (pre-antivenom therapy [T0], 24 h [T1], and 48 h [T2] after antivenom therapy). The profile of the circulating inflammatory response is different between the groups studied, with HF patients having higher concentrations of CCL-5 and lower IFN-γ. In addition, antivenom therapy seems to have a positive effect, leading to a profile of circulating inflammatory response similar in quantification of T1 and T2 on both groups. Furthermore, these results suggest that a number of interactions of CXCL-8, CXCL-9, CCL-2, IL-6, and IFN-γ in HF patients are directly affected by fibrinogen levels, which may be related to the inflammatory response and coagulation mutual relationship induced by B. atrox venom. The present study is the first report on inflammation-coagulation crosstalk involving snakebite patients and supports the better understanding of envenomation's pathophysiology mechanisms and guides in the search for novel biomarkers and prospective therapies.

The Matrikine Acetylated Proline-Glycine-Proline Couples Vascular Inflammation and Acute Cardiac Rejection

The extracellular matrix (ECM) is a dynamic, bioactive structure critical to organ development, structure and function. Excessive remodeling of the ECM is a hallmark of a variety of inflammatory conditions including vascular disease. Endothelin-1 (ET1) synthesis is understood to promote cardiovascular diseases including acute cardiac transplant rejection; however, the contribution of ECM-derived chemokines (matrikines) to vascular inflammation remains poorly understood. Herein we report that the matrikine acetylated Pro-Gly-Pro (PGP) stimulates vascular inflammation through activation of endothelial CXC Chemokine Receptor 2 (CXCR2) and production of endothelin-1 both in vitro and in vivo. As a proof of hypothesis, we demonstrate that coronary PGP levels associate with both circulating endothelin-1 and acute rejection in cardiac transplant patients (sensitivity of 100% and specificity of 86%). These findings establish PGP as a novel mediator in cardiovascular disease, and implicate bioactive matrix fragments as underappreciated agents potentially active in numerous conditions propagated by progressive vascular inflammation.

Inflammatory and Immune Activation in Intestinal Myofibroblasts Is Developmentally Regulated

We previously demonstrated that intestinal myofibroblasts from immature tissue produce excessive IL-8 in response to Escherichia coli lipopolysaccharide (LPS) compared to cells from mature tissue. However, it is unknown whether other cytokines and TLR agonists contribute to this developmentally regulated response. The aim of this study was to further characterize differences in inflammatory signaling in human primary intestinal fibroblasts from fetal (FIF) and infant (IIF) tissue and examine their potential to activate the adaptive immune response in vitro. Cytokine profiles of LPS-stimulated FIF and IIF were assessed by cytokine profile array. IL-8, IL-6, and IL-10 production in response to TLR2, TLR2/6, TLR4, and TLR5 agonists was determined by quantitative ELISA. The potential of activated myofibroblasts to activate adaptive immunity was determined by measuring surface class II MHC expression using flow cytometry. LPS-stimulated FIF produced a distinct proinflammatory cytokine profile consisting of MCP-1, GRO-alpha, IL-6, and IL-8 expression. FIF produced significant IL-8 and IL-6 in response to TLR4 agonist. IIF produced significant levels of IL-8 and IL-6 in the presence of TLR5 and TLR2 agonists. IFN-γ-treated FIF expressed greater HLA-DR levels compared to unstimulated controls and IFN-γ- and LPS-treated IIF. Activated FIF produce a more diverse inflammatory cytokine profile and greater levels of IL-8 and IL-6 in response to TLR4 stimulation compared to IIF. FIF express class II MHC proteins associated with activation of the adaptive immune response. These data suggest that FIF may contribute to bacterial-associated gut inflammation in the immature intestine.

Mesenchymal Stem Cells Ameliorate Atherosclerotic Lesions via Restoring Endothelial Function

Transplantation of mesenchymal stem cells (MSCs) is beneficial in myocardial infarction and hind limb ischemia, but its ability to ameliorate atherosclerosis remains unknown. Here, the effects of MSCs on inhibiting endothelial dysfunction and atherosclerosis were investigated in human/mouse endothelial cells treated with oxidized low-density lipoprotein (oxLDL) and in apolipoprotein E-deficient (apoE-/-) mice fed a high-fat diet. Treatment with oxLDL inactivated the Akt/endothelial nitric-oxide synthase (eNOS) pathway, induced eNOS degradation, and inhibited nitric oxide (NO) production in endothelial cells. Coculture with human MSCs reversed the effects of oxLDL on endothelial cells and restored Akt/eNOS activity, eNOS level, and NO production. Reduction of endothelium-dependent relaxation and subsequent plaque formation were developed in apoE-/- mice fed a high-fat diet. Systemic infusion with mouse MSCs ameliorated endothelial dysfunction and plaque formation in high-fat diet-fed apoE-/- mice. Interestingly, treatment with interleukin-8 (IL8)/macrophage inflammatory protein-2 (MIP-2) alone induced the similar effects of human/mouse MSCs on oxLDL-treated human/mouse endothelial cells. Neutralization antibodies (Abs) against IL8/MIP-2 also blocked the effects of human/mouse MSCs on oxLDL-treated human/mouse endothelial cells. Consistently, MIP-2 injection alone induced the similar effect of MSCs on the endothelial function in high-fat diet-fed apoE-/- mice. The improvement in endothelial dysfunction by mouse MSCs was also blocked when pretreating MSCs with anti-MIP-2 Abs. In conclusion, MSC transplantation improved endothelial function and plaque formation in high-fat diet-fed apoE-/- mice. Activation of the Akt/eNOS pathway in endothelium by IL8/MIP-2 is involved in the protective effect of MSCs. The study helps support the use and clarify the mechanism of MSCs for ameliorating atherosclerosis.

Regulation of MMP/TIMP by HUVEC transplantation attenuates ventricular remodeling in response to myocardial infarction

AIMS

We elucidated the therapeutic potential of human umbilical vein endothelial cells (HUVECs) for ameliorating progressive heart failure in a myocardial infarction (MI) rat model.

MAIN METHODS

MI was induced by ligation of left anterior descending artery, and HUVEC was transplanted 1week after MI. Cardiac function was evaluated by echocardiography, and histological analyses were performed.

KEY FINDINGS

Phosphate-buffered saline (MI-V, n=5) or HUVEC (MI-HV, n=5) were injected into the border zone and infarcted area 7days after ligation of the left coronary artery in rats. The MI-HV group showed attenuation of left ventricular (LV) remodeling compared with the MI-V group. In the infarcted myocardium, a few of injected HUVEC was retained up to 28days. The ratios of matrix metalloproteinase (MMP)-2 or MMP-9 to tissue inhibitor of metalloproteinase (TIMP)-1 or TIMP-3 were decreased in the MI-HV group compared with the MI-V group. In vivo zymography analysis showed that HUVEC transplantation decreased the activities of MMP-2 and MMP-9. In immunohistochemistry, decreased MMP-2 and increased TIMP-1 and TIMP-3 expression were observed at 48h after HUVEC transplantation. These effects on MMP/TIMP balance were inhibited by L-NAME administration (an eNOS inhibitor, 10mg/kg). NOS inhibition decreased the protein expressions of TIMP-1 and TIMP-3 but did not change the protein expressions of MMP-2 and MMP-9.

SIGNIFICANCE

Our data suggest that altered balance between MMP and TIMP by HUVEC transplantation contributed to attenuation of ventricular remodeling after MI via eNOS.

The proinflammatory effect of C-reactive protein on human endothelial cells depends on the FcγRIIa genotype

INTRODUCTION

The stimulatory effects of CRP (C-reactive protein) on endothelial cells are mainly mediated via FcγRIIa. This receptor exists in two different allotypes bearing either arginine (R131) or histidine (H131) at the extracellular amino acid position 131 of the mature protein, but only FcγRIIa-R131 displays high avidity for CRP. This study investigated the role of the FcγRIIa genotype in CRP-stimulated endothelial cells.

MATERIALS AND METHODS

We tested the effects of CRP on expression of the adhesion molecules ICAM-1, VCAM-1, and E-selectin, as well as the endothelial release of pro-inflammatory molecules as a function of the FcγRIIa-genotype (FcγRIIa-H/H131, FcγRIIa-H/R131, FcγRIIa-R/R131) in HUVEC (Human Umbilical Vein Endothelial Cells). HUVEC were grouped according to their FcγRIIa status by genotyping with an allele specific nested-PCR. The expression of ICAM-1, VCAM-1, and E-selectin on HUVEC was detected by flow cytometry. The release of soluble markers (sCD40L, IL-6, IL-8, MCP-1, tPA, sP-selectin, and sVCAM-1) was measured using a multiplex assay for flow cytometry.

RESULTS AND CONCLUSIONS

CRP-stimulated expression of ICAM-1 and E-selectin was dependent on the specific FcγRIIa-genotype, with most pronounced induction in HUVEC with the FcγRIIa-R/R genotype, followed by H/R and H/H. In accordance with this finding, the supernatants of stimulated HUVEC with the R/R genotype showed significantly higher levels of tPA, MCP-1, and IL-6. Our data show that CRP stimulates the expression of adhesion molecules and the release of soluble markers by HUVEC as a function of the FcγRIIa-genotype. These findings could be relevant in the context of risk stratification in patients with cardiovascular disease.

The potential contribution of tumour-related factors to the development of FOLFOX-induced sinusoidal obstruction syndrome

Background:

Chemotherapy-associated liver injury (CALI) has been linked to increased morbidity and poorer disease-specific outcomes in patients undergoing resection of colorectal liver metastases (CRLM). The aim of this study was to assess the contribution of tumour-related factors to the development of FOLFOX-induced liver injury.

Methods:

We assessed the effect of FOLFOX treatment on the murine liver either in the presence or absence of CRLM to evaluate the contribution of both chemotherapy and tumour death to the development of CALI.

Results:

In the presence of liver metastases, there was increased hepatic expression of plasminogen activator inhibitor-1 (146-fold; P<0.01) and vWF (2.4-fold; P<0.01) transcript as compared with sham-operated controls. In addition, we detected large clusters of megakaryocytes in the spleen of FOLFOX-treated tumour-bearing animals. The livers of FOLFOX-treated animals also showed changes in matrix remodelling genes such as TGFβ (P<0.01), MMP2 (P<0.001), TIMP1 (P<0.001) and Pro-Collagen I (P<0.05) which was exacerbated in the presence of tumour. These genes have previously been demonstrated to have a key role in FOLFOX-induced liver injury.

Conclusion:

It appears that the toxicity of FOLFOX chemotherapy is enhanced by tumour-related factors.

Endothelial progenitor cells: current development of their paracrine factors in cardiovascular therapy

Endothelial progenitor cells were initially considered to radically alter the concepts of adult tissue angiogenesis for their contribution of incorporation into new blood vessels. Nevertheless, controversy arises over their mechanism of action due to rare cell population and decreased number and impaired activity under pathological changes. Recent studies show that endothelial progenitor cells also function in a paracrine manner by secreting multiple cytokines and growth factors, but the beneficial paracrine signals remain partially unidentified. In this review, we provide an overview of varieties and signal pathways of factors secreted by endothelial progenitor cells and further present the prospect of new ways to encourage cardiovascular protection such as neovascularization, reendothelialization of larger vessels, and myocardial remodeling based on the paracrine factors.

Galvanotactic migration of EA.Hy926 endothelial cells in a novel designed electric field bioreactor

Endogenous direct current electric fields (dcEFs) play a significant role in major biological processes such as embryogenesis, wound healing, and tissue regeneration. In this study, the galvanotaxis of human umbilical vein endothelial cell line EA.Hy926 was investigated by using a novel designed bioreactor. The physical features of the bioreactor were discussed and analyzed by both numerical simulation method and equivalent circuit model method. EA.Hy926 cells were cultured in the bioreactor for 10-24 h under 50-250 mV/mm dcEFs. Cell migration direction, distance, and velocity were recorded under an online time-lapse microscope. The effects of serum and growth factor on cell galvanotatic migration were investigated. To further explore the role of dcEFs in regulating endothelial cells, we analyzed the endothelial cell proliferation and secretion of nitric oxide (NO), endothelin-1 (ET-1) in response to dcEFs of physiological strength. Our results showed that EA.Hy926 cells had an obvious directional migration to the cathode, and the EF-directed migration was voltage dependent. The results also showed dcEFs did not affect cell proliferation, but affected the productions of NO and ET-1. Our study also showed the novel bioreactor, with a compact and planar style, makes it more convenient and more reasonable for EF stimulation experiments than earlier chamber designs.

Antioxidant activities of aqueous leaf extracts of Toona sinensis on free radical-induced endothelial cell damage

ETHNOPHARMACOLOGICAL RELEVANCE

In Taiwan, Toona sinensis (Toona sinensis) is well known as a traditional Chinese medicine, while the underlying pharmacological mechanisms of this drug are still a matter of debate.

MATERIALS AND METHODS

The purpose of this study was to evaluate the protective effects of non-cytotoxic concentrations of aqueous leaf extracts of Toona sinensis (TS extracts; 50-100 μg/mL) and gallic acid (5 μg/mL), a major component of these extracts, against AAPH-induced oxidative cell damage in human umbilical vein endothelial cells (ECs).

RESULTS

Exposure of ECs to AAPH (15 mM) decreased cell viability from 100% to 43%. However, ECs were pre-incubated with TS extracts prior to AAPH induction resulted in increased resistance to oxidative stress and cell viability in a dose-dependent manner. An increase in ECs-derived PGI(2) and IL-1 β in response to AAPH exposure was positively correlated with cytotoxicity and negatively with TS extracts concentrations. In addition, gallic acid also suppressed PGI(2) and IL-1 β production in AAPH-induced ECs. Notably, TS extracts/gallic acid treatment significantly inhibited ROS generation, MDA formation, SOD/catalase activity, and Bax/Bcl-2 dysregulation in AAPH-stimulated ECs. Pretreatment of ECs with TS extracts/gallic acid also suppressed AAPH-induced cell surface expression and secretion of VCAM-1, ICAM-1 and E-selectin, which was associated with abridged adhesion of U937 leukocytes to ECs. Moreover, TS extracts/gallic acid treatment significantly inhibited the AAPH-mediated up regulation of PAI-1 and down regulation of t-PA in ECs, which may decrease fibrinolytic activity.

CONCLUSIONS

Therefore, Toona sinensis may possess antioxidant properties that protect endothelial cells from oxidative stress. Our results also support the traditional use of Toona sinensis in the treatment of free radical-related diseases and atherosclerosis.

Role for nuclear factor-kappaB in augmented lung injury because of interaction between hyperoxia and high stretch ventilation

High-tidal-volume mechanical ventilation and hyperoxia used in patients with acute lung injury (ALI) can induce alveolar coagulopathy and fibrin depositions within the airways. Hyperoxia has been shown to increase ventilator-induced lung injury (VILI), but the mechanisms that regulate interaction between high-tidal-volume mechanical ventilation and hyperoxia are unclear. We hypothesized that mechanical stretch with hyperoxia synergistically augmented neutrophil infiltration and production of plasminogen activator inhibitor-1 (PAI-1) via the nuclear factor-kappaB (NF-kappaB) pathway. C57BL/6 mice (n=5 per group) were exposed to high-tidal-volume (30 mL/kg) or low-tidal-volume (6 mL/kg) mechanical ventilation with room air or hyperoxia for 1 to 5h after 2-microg/g NF-kappaB inhibitor (SN-50) administration. Nonventilated mice with room air or hyperoxia served as control groups. Evans blue dye, myeloperoxidase, electrophoretic mobility shifting of nuclear protein, and inflammatory cytokine were measured. The expression of tumor necrosis factor-alpha (TNF-alpha) and PAI-1 were studied by immunohistochemistry. The addition of hyperoxia to high-tidal-volume ventilation-augmented lung injury, as demonstrated by increased microvascular leak, neutrophil migration into the lung, TNF-alpha and active PAI-1 production, DNA binding activity of NF-kappaB, and NF-kappaB activation. No statistically significant increase of neutrophil infiltration and inflammatory cytokine production was found in the mice ventilated at 6 mL/kg using hyperoxia. Hyperoxia-induced augmentation of VILI was attenuated in mice with pharmacologic inhibition of NF-kappaB activity by SN-50. We conclude that hyperoxia increased high-tidal-volume-induced cytokine production and neutrophil influx through activation of the NF-kappaB pathway.

Interleukin 8 is differently expressed and modulated by PAR-1 activation in early and late endothelial progenitor cells

The proinflammatory chemokine interleukin 8 exerts potent angiogenic effects on endothelial cells by interacting with its receptors CXCR1 and CXCR2. As thrombin is also a potent inflammatory factor, and as endothelial progenitor cells (EPC) express functional PAR-1 thrombin receptor, we examined whether PAR-1 stimulation interferes with the IL-8 pathway in EPC. EPC were obtained from adult blood (AB) and cord blood (CB). The effect of PAR-1 stimulation by the peptide SFLLRN on IL-8, CXCR1 and CXCR2 expression was examined by RTQ-PCR and at the protein level in AB and CB late EPC and in AB early EPC. Specific siRNA was used to knock down PAR-1 expression. The IL-8 gene was expressed strongly in AB early EPC and moderately in late EPC. In contrast, CXCR1 and CXCR2 gene expression was restricted to AB early EPC. The IL-8 level in AB early EPC conditioned medium was high in basal conditions and did not change after PAR-1 activation. By contrast, IL-8 secretion by late EPC was low in basal conditions and strongly up-regulated upon PAR-1 activation. PAR-1 activation induced a number of genes involved in activating protein-1 (AP-1) and nuclear factor (NF)-kappaB pathways. Conditioned medium of PAR-1-activated late EPC enhanced the migratory potential of early EPC, and this effect was abrogated by blocking IL-8. Target-specific siRNA-induced PAR-1 knockdown, and fully inhibited PAR-1-induced IL-8 synthesis. In conclusion, PAR-1 activation induces IL-8 synthesis by late EPC. This could potentially enhance cooperation between late and early EPC during neovascularization, through a paracrine effect.

Comparison of angiogenesis-related factor expression in primary tumor cultures under normal and hypoxic growth conditions

Background

A localized hypoxic environment occurs during tumor growth necessitating an angiogenic response or tumor necrosis results. Novel cancer treatment strategies take advantage of tumor-induced vascularisation by combining standard chemotherapeutic agents with angiogenesis-inhibiting agents. This has extended the progression-free interval and prolonged survival in patients with various types of cancer. We postulated that the expression levels of angiogenesis-related proteins from various primary tumor cultures would be greater under hypoxic conditions than under normoxia.

Methods

Fifty cell sources, including both immortalized cell lines and primary carcinoma cells, were incubated under normoxic conditions for 48 hours. Then, cells were either transferred to a hypoxic environment (1% O₂) or maintained at normoxic conditions for an additional 48 hours. Cell culture media from both conditions was collected and analyzed via an ELISA-based assay to determine expression levels of 11 angiogenesis-related factors: VEGF, PDGF-AA, PDGF-AA/BB, IL-8, bFGF/FGF-2, EGF, IP-10/CXCL10, Flt-3 ligand, TGF-β1, TGF-β2, and TGF-β3.

Results

A linear correlation between normoxic and hypoxic growth conditions exists for expression levels of eight of eleven angiogenesis-related proteins tested including: VEGF, IL-8, PDGF-AA, PDGF-AA/BB, TGF-β1, TGF-β2, EGF, and IP-10. For VEGF, the target of current therapies, this correlation between hypoxia and higher cytokine levels was greater in primary breast and lung carcinoma cells than in ovarian carcinoma cells or tumor cell lines. Of interest, patient cell isolates differed in the precise pattern of elevated cytokines.

Conclusion

As linear correlations exist between expression levels of angiogenic factors under normoxic and hypoxic conditions in vitro, we propose that explanted primary cells may be used to probe the in vivo hypoxic environment. Furthermore, differential expression levels for each sample across all proteins examined suggests it may be possible to build a predictor for angiogenesis-related anticancer agents, as each sample has a unique expression profile. Further studies should be performed to correlate in vitro protein expression levels of angiogenesis-related factors with in vivo patient response.