Large extracellular vesicle (EV) and neutrophil extracellular trap (NET) interaction captured in vivo during systemic inflammation

Extracellular vesicles (EVs) and neutrophil extracellular traps (NETs) are pivotal bioactive structures involved in various processes including inflammation. Herein we report the interactions between EVs and NETs during murine endotoxemia studied in situ directly in the vasculature (cremaster muscle, liver sinusoids) using intravital microscopy (IVM). We captured NETs and EV release in real time by both non- and polarized neutrophils in liver but not in cremaster vasculature. When comparing numbers of circulating EVs of various origin (nanoparticle tracking analysis-NTA, flow cytometry) with those interacting with endothelium and NETs (IVM) we observed that whereas platelet and monocyte/macrophage-derived EVs dominate in blood and peritoneal lavage, respectively, mostly neutrophil-derived EVs interact with the vascular lining, NETs and leukocytes. Despite the interaction, NETs do not affect EV formation as NET release inhibition did not alter EV release. However, EVs inhibit NETs formation and in particular, erythrocyte-derived EVs downregulate NET release and this effect is mediated via Siglec-E-dependent interactions with neutrophils. Overall, we report that EVs are present in NETs in vivo and they do modulate their release but the process in not bidirectional. Moreover, EVs isolated from body fluids might not reflect their importance in direct endothelial- and leukocyte-related interactions.

Activation of cardiac macrophages, endothelial cells and fibroblasts in experimental autoimmune myocarditis

Background/Introduction

Inflammation of cardiac tissue, termed myocarditis, is a common cause of dilated cardiomyopathy associated with abnormal tissue remodeling, stiffening of ventricles and heart failure. Experimental autoimmune myocarditis (EAM) represents CD4+ T cell-dependent animal model of acute myocarditis followed by development of cardiomyopathy, cardiac fibrosis and systolic dysfunction.

Purpose

The aim of the study was to investigate the role of cardiac macrophages, endothelial cells and fibroblasts in myocarditis and post-inflammatory cardiomyopathy in mouse model of EAM.

Methods

EAM was induced in BALB/c mice by immunization with alpha myosin heavy chain and complete Freund's adjuvant. Reporter mice expressing EGFP under collagen type I promoter (Coll-EGFP), transgenic αSMA-TK mice with ganciclovir-inducible ablation of proliferating myofibroblasts and Rosa26-YFP/LysM-Cre and Rosa26-YFP/LysM-Cre/Tgfbr2 fl/fl with YFP expression and Tgfbr2 deletion in myeloid cell population were used in this study. Cardiac fibroblasts and macrophages were sorted using BD FACSAria™ II Cell Sorter and analyzed for the genome transcriptomics by RNA sequencing. Echocardiography was performed on Vevo 2100 Imaging System. Cardiac fibrosis was measured as percentage of fibrotic area using Trichrome Massons's staining and by hydroxyproline assay. Cardiac hypertrophy was analyzed as means of cross-sectional cardiomyocyte area. Monocytes and endobcells were analyzed using BD FACSCanto™ II flow cytometry.

Results

Cardiac fibroblasts in response to acute myocarditis (d21 of EAM) showed activation of immune processes (mainly chemokine production such as Ccl6, Ccl9, Cxcl2, Cxcl3, Cxcl5, Cxcl9, Cxcl13), cytoskeletal re-organization (Cxadr, F11r, Gdpd2, Krt8, Krt19, Ptk2b, Rac2, Rhov, Rnd1, S100a9, Spire2, Was) and upregulation of genes involved in extracellular matrix turnover (Bmp7, Kng2, Lgals3, Cthrc1, Cela1, Spn) including collagens. Ablation of myofibroblasts (between d21–40 of EAM) resulted in markedly reduced heart weight and cardiomyocyte hypertrophy, attenuated expression of genes related to hypertrophy (Acta1, Actc1, Bnp, Cfl2, Pdlim5), improved stroke volume, ejection fraction and cardiac output but did not prevent development of post-inflammatory cardiac fibrosis measured at d40 of EAM. Analysis of monocytes and endothelial cells indicated excessive production of type I collagen by these cells at d21. Analysis of cardiac macrophages pointed out TGF-β-dependent expression of cytokines (Ifn, Il23a, Il10, Il12b, Cxcl1, Tnf) and theirs receptors (Cxcr1, Ccr4) at d21 of EAM.

Conclusions

Acute myocarditis activates proinflammatory and profibrotic responses in cardiac resident cells. Our data suggest that cardiac myofibroblasts play a particularly important role in development of post-inflammatory cardiomyopathy and heart failure. Targeting cardiac myofibroblasts might therefore represent a novel therapeutic strategy in inflammatory heart disease.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): National Science Centre (Poland)

Activated myofibroblasts promote cardiac hypertrophy and systolic dysfunction independently of cardiac fibrosis in experimental autoimmune myocarditis

Background/Introduction

Heart-specific inflammation – myocarditis is a common cause dilated cardiomyopathy which is characterized by pathological tissue remodeling, ventricular stiffening, cardiomyopathy and heart failure. In experimental autoimmune myocarditis (EAM) susceptible mice immunized with alpha myosin heavy chain (αMyHC) and complete Freund's adjuvant (CFA) develop acute myocarditis driven by autoreactive CD4+ T cells that is followed by progressive fibrosis, cardiomyopathy and systolic dysfunction.

Purpose

The aim of the study was to investigate the role of cardiac fibroblasts and myofibroblasts in myocarditis and post-inflammatory dilated cardiomyopathy in mouse model of EAM.

Methods

EAM was induced in BALB/c mice by immunization with αMyHC/CFA. We used reporter mice expressing EGFP under collagen type I promoter (Coll-EGFP) and RFP under a control of α-smooth muscle actin (αSMA) promoter (αSMA-RFP) and transgenic αSMA-TK mice with ganciclovir-inducible ablation of proliferating myofibroblasts. Cardiac cells were quantified using flow cytometry. Cardiac fibroblasts (CD45-CD31-EGFP+) were sorted from healthy and myocarditis-positive (day 21) mice using BD FACSAria™ II Cell Sorter and analyzed for the whole genome transcriptomics by RNA sequencing. Echocardiography was performed on Vevo 2100 Imaging System. Cardiac fibrosis was assessed by Trichrome Massons's staining and hydroxyproline assay, whereas cardiac hypertrophy by analysing cross-sectional cardiomyocyte area. Profibrotic gene expression was assessed by qRT-PCR.

Results

The total number of cardiac fibroblasts (CD45-CD31-EGFP+) and the subset of myofibroblasts (CD45-CD31-EGFP+RFP+) remained unchanged at inflammatory (d21) and fibrotic stages (d40). Analysis of differentially expressed genes (min. 2x fold change, p value <0.05) pointed out activation of immune processes (mainly chemokine production), response to stress, cytoskeletal and extracellular matrix re-organization in cardiac fibroblasts in response to myocarditis. αSMA-TK mice treated with ganciclovir (from day 21) showed comparable percent of fibrotic area, but significantly reduced heart weight, decreased cardiomyocyte hypertrophy and improved ejection fraction and cardiac output at day 40 comparing to PBS-treated mice. Ganciclovir-treated mice showed also attenuated cardiac Acta2 and Srf but markedly enhanced Mmp2 expression.

Conclusions

In EAM model cardiac fibroblasts actively participate in proinflammatory and profibrotic responses, while activated myofibroblasts contribute to dilated cardiomyopathy development independently of cardiac fibrosis.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): National Science Centre (Poland)

Terphenyl-Based Small-Molecule Inhibitors of Programmed Cell Death-1/Programmed Death-Ligand 1 Protein-Protein Interaction

We describe a new class of potent PD-L1/PD-1 inhibitors based on a terphenyl scaffold that is derived from the rigidified biphenyl-inspired structure. Using in silico docking, we designed and then experimentally demonstrated the effectiveness of the terphenyl-based scaffolds in inhibiting PD-1/PD-L1 complex formation using various biophysical and biochemical techniques. We also present a high-resolution structure of the complex of PD-L1 with one of our most potent inhibitors to identify key PD-L1/inhibitor interactions at the molecular level. In addition, we show the efficacy of our most potent inhibitors in activating the antitumor response using primary human immune cells from healthy donors.

Myocarditis triggers inflammatory response in cardiac fibroblasts and profibrotic activation of myeloid and endothelial cells in mouse model of experimental autoimmune myocarditis

Background/Introduction

Myocarditis, a heart-specific inflammation, is a common cause of pathological tissue remodeling and cardiac fibrosis resulting in stiffening of ventricles, functional impairment and heart failure. Immunization of susceptible mice with alpha myosin heavy chain (αMyHC) and complete Freund's adjuvant (CFA) induces CD4+ T cell-mediated experimental autoimmune myocarditis (EAM). In EAM model, resolution of acute cardiac inflammation is followed by a progressive dilated cardiomyopathy and systolic dysfunction.

Purpose

The aim of our study was to identify the role of resident cardiac fibroblasts, cardiac endothelial as well as inflammatory myeloid cells during the course of EAM.

Methods

EAM was induced by immunization with αMyHC/CFA in reporter BALB/c mice expressing EGFP under collagen type I promoter (Coll-EGFP) and RFP under a control of α-smooth muscle actin (αSMA) promoter (αSMA-RFP). Using flow cytometry analysis, cardiac cells were phenotyped and quantified at inflammatory (d19–21) and fibrotic (d40) stage of EAM. Sorted EGFP-positive cardiac fibroblasts obtained from healthy and myocarditis-positive mice (day 21 of EAM) were comparatively analyzed for the whole genome transcriptomics using the Next Generation Sequencing with read length 2x150bp and 20–30 million reads per sample.

Results

A massive infiltration of inflammatory CD45+CD11b+ myeloid cells (mainly CD11b+CD36+ macrophages, CD11b+CD36–Ly6GhiLy6chi neutrophils, CD11b+CD36–Ly6G–Ly6c– monocytes, CD11b+CD36–Ly6G–Ly6chi inflammatory monocytes) was observed at day 21 of EAM. Myeloid cells as well as endothelial cells showed increased production of type I collagen at day 21, which was further reduced at day 40 of EAM. At day 21, collagen-producing endothelial cells showed particularly elevated levels of adhesion molecules ICAM and VCAM. On the other hand, the total number of EGFP-positive cardiac fibroblasts remained unchanged during the course of EAM, as well as the percentage of cardiac fibroblasts positive for αSMA (myofibroblasts). Gene ontology analysis of transcripts differentially regulated in cardiac fibroblasts during acute myocarditis pointed mainly to activation of immune processes, response to stress, cytoskeletal and extracellular matrix organization. Specifically, in EAM at day 21 cardiac fibroblasts increased transcription of chemokines (Ccl6, Ccl9, Cxcl2, Cxcl3, Cxcl5, Cxcl9, Cxcl13), collagens (Col6a4, Col6a5, Col9a1, Col9a3, Col11a2, Col12a1, Col24a1, Col28a1), and genes involved in ECM biology (Bmp7, Kng2, Lgals3, Cthrc1, Cela1, Spn).

Conclusions

In EAM model, inflammatory myeloid and cardiac endothelial cells seem to contribute to excessive collagen type I production, whereas cardiac fibroblasts actively participate in inflammatory and profibrotic responses.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): The National Science Centre (Poland)

TNF-alpha protects from exacerbated autoinflammatory response in mouse model of experimental autoimmune myocarditis

Background

Myocarditis is an inflammatory heart disease and heart-specific autoimmunity plays an important role in development and progression of the disease. TNF-α is a potent pro-inflammatory cytokine implicated in pathogenesis in many inflammatory diseases. Unexpectedly, clinical studies showed that high dose anti-TNF-α therapy increased hospitalization and mortality of heart failure patients.

Purpose

To elucidate the role of TNF-α in heart-specific autoimmunity and in activation of cardiac microvascular endothelial cells in autoimmune response.

Methods

Experimental autoimmune myocarditis (EAM) was induced in BALB/c mice by immunization with

α-myosin heavy chain peptide (α-MyHC) together with complete Freund's adjuvant. Development of myocarditis in the absence of adjuvant was analysed in TCR-M mice, which CD4+ T cells expressed transgenic T cell receptor recognizing α-MyHC. The role of TNF-α was addressed using haploinsufficient Tnf+/−, knockout Tnf−/− and TCR-M x Tnf+/− mice. Effects of antigen-dependent T cell response on cardiac microvascular endothelial cell (cMVEC) activation were assessed by flow cytometry, immunoblotting and leukocyte-endothelium adhesion assay. Inflammatory cells were phenotyped using flow cytometry, cytokine production was measured by ELISA.

Results

EAM induction resulted in reduced prevalence of myocarditis in Tnf+/− and Tnf−/− comparing wild-type mice at day 21 after disease induction. However, Tnf+/− and Tnf−/− mice that developed myocarditis showed higher severity of the disease than wild-type controls. On the other hand, TCR-M x Tnf+/− mice showed exacerbated myocarditis at age of 2 months and were characterized by increased mortality comparing with TCR-M controls. TCR-M Tnf+/− mice showed increased total number of cardiac infiltrates compared to TCR-M controls, but no difference in myeloid subsets were observed. In contrast, Tnf+/− and Tnf−/− mice showed significantly increased percentage of T effector cells in spleens and blood in both myocarditis models. Stimulation with rTNF-α induced expression of intercellular adhesion molecules (ICAM1, VCAM1 and P-selectin) on cMVECs, which was associated with increased ability to bind leukocytes under shear flow conditions. TNF-α deficiency had, however, no impact on antigen-specific activation and proliferation of T-cells. Medium conditioned of antigen-activated wild-type, Tnf+/− and Tnf−/− CD4+ T cells showed similar cMVEC activation measured by increased expression of intercellular adhesion molecules and binding of leukocytes under shear flow condition. Furthermore, Tnf+/− and Tnf−/m- myeloid cells showed increased production of IL-6.

Conclusions

Our data suggest that TNF-α protects the heart from excessive autoimmune reaction by suppressing expansion of autoreactive effector T cells. Thus, this study uncovers a cardioprotective role of proinflammatory TNF-α and potentially can explain the deleterious effect of high dose anti-TNF-α therapy in heart failure patients.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): The National Science Centre Poland

The specific ex vivo released cytokine profile is associated with ischemic stroke outcome and improves its prediction

Background

Inflammation is associated with poor outcome after stroke. A relationship between ex vivo cytokine synthesis and stroke outcome remains unclear. We explored an association between ex vivo cytokine release, circulating interleukin (IL)-6 as a marker of systemic inflammation, and stroke prognosis. We assessed the utility of ex vivo synthesized cytokines for predicting stroke outcome.

Methods

We collected blood from 248 ischemic stroke patients and stimulated it ex vivo with lipopolysaccharide. We measured concentration of synthesized cytokines (TNFα, IP-10, IL-1β, IL-6, IL-8, IL-10, and IL-12) and plasma IL-6. We assessed functional outcome 3 months after stroke using the modified Rankin Scale. To assess the prognostic ability of cytokines, we applied multivariate logistic regression, cluster analysis, and construction of multimarker score.

Results

Decreased release of IP-10, TNFα, IL-1β, and IL-12; increased release of IL-10 and IL-8; and higher plasma IL-6 level were associated with poor outcome. Cluster analysis identified three groups of patients with distinct cytokine profiles. The group with the worst outcome demonstrated high synthesis of IL-10, IL-8, IL-1β, and IL-6 and low synthesis of IL-12, IP-10, and TNFα accompanied by high circulating IL-6 level. The group with the best prognosis showed high synthesis of TNFα, IP-10, IL-12, IL-1β, and IL-6; low synthesis of IL-10 and IL-8; and low plasma IL-6. Patients with intermediate outcome had low synthesis of all cytokines accompanied by low circulating IL-6. We constructed a multimarker score composed of ex vivo released IL-12, IL-10, TNFα, and plasma IL-6. Addition of this score to clinical variables led to significant increase in c-statistic (0.81 vs 0.73, p = 0.02) and net reclassification improvement.

Conclusion

The decreased ex vivo release of pro-inflammatory cytokines and increased release of IL-10 and IL-8 are related to poor outcome after stroke. Cytokine-based multimarker score adds prognostic value to clinical model for predicting stroke outcome.

Protumorogenic Potential of Pancreatic Adenocarcinoma-Derived Extracellular Vesicles

Cancer development is a highly complicated process in which tumour growth depends on the development of its vascularization system. To support their own growth, tumour cells significantly modify their microenvironment. One of such modifications inflicted by tumours is stimulation of endothelial cell migration and proliferation. There is accumulating evidence that extracellular vesicles (EVs) secreted by tumour cells (tumour-derived EVs, TEVs) may be regarded as "messengers" with the potential for affecting the biological activities of target cells. Interaction of TEVs with different cell types occurs in an auto- and paracrine manner and may lead to changes in the function of the latter, e.g., promoting motility, proliferation, etc. This study analysed the proangiogenic activity of EVs derived from human pancreatic adenocarcinoma cell line (HPC-4, TEVHPC) in vitro and their effect in vivo on Matrigel matrix vascularization in severe combined immunodeficient (SCID) mice. TEVHPC enhanced proliferation of HPC-4 cells and induced their motility. Moreover, TEVHPC stimulated human umbilical vein endothelial cell (HUVEC) proliferation and migration in vitro. Additionally, TEVHPC influenced secretion of proangiogenic factors (IL-8, VEGF) by HUVEC cells and supported Matrigel matrix haemoglobinization in vivo. These data show that TEVs may support tumour propagation in an autocrine manner and may support vascularization of the tumour. The presented data are in line with the theory that tumour cells themselves are able to modulate the microenvironment via TEVs to maximize their growth potential.

Autologous tumor‑derived microvesicles influence gene expression profiles and enhance protumorigenic chemotactic potential, signal transduction and cellular respiration in gastric cancer cells

Tumor‑derived microvesicles (TMVs) interact with a variety of different cell types within the immune system, including lymphocytes, monocytes, dendritic cells and tumor cells that they have originated from. In the present study, the effects of autologous‑TMVs (auto‑TMVs) on gene expression, chemotaxis, intercellular signaling and cellular metabolism were examined in cells of the gastric cancer (GC) cell line 1415 (GC1415). The effects of auto‑TMVs on mRNA gene expression in GC1415 cells were assessed using pathway‑focused PCR arrays. A chemotaxis assay was performed using the HoloMonitor M4 System. Signaling pathways were evaluated using western blot analysis, and cellular respiration was measured using the Seahorse XF Cell Mito Stress Test. Exposure of the GC1415 cells to auto‑TMVs led to the overexpression (75 genes) and underexpression (96 genes) of genes that are associated with signal transduction, metabolism, chemotaxis, angiogenesis and metastasis. The auto‑TMVs were indicated to induce chemotaxis and activate the PI3K/AKT signaling pathway in GC1415 cells. However, the MAPK/ERK signaling pathway was not indicated to be activated. Furthermore, studies on cellular respiration in GC1415 cells exposed to auto‑TMVs demonstrated a metabolic shift to glycolysis. The results of the current study thus indicate that auto‑TMVs may exert an effect on tumor cell function.

The role of CD44H molecule in the interactions between human monocytes and pancreatic adenocarcinoma-derived microvesicles

INTRODUCTION

CD44H is a transmembrane molecule important for cell-cell and cell-extracellular matrix interactions. In monocytes, CD44H is implicated in phagocytosis of particles coated by hyaluronan (HA). HA fragments were shown to induce chemokine secretion by monocytes. Tumour derived microvesicles (TMVs), which are small membrane fragments derived from tumour cells can carry fragments of HA. The aim of the study was to examine whether monocyte's CD44H is involved in the engulfment of pancreatic adenocarcinoma-derived microvesicles and in the production of chemokines induced by TMVs.

MATERIALS AND METHODS

TMVs engulfment and chemokines' secretion stimulated with TMVs were determined in control human monocytes and cells incubated with anti-CD44H monoclonal antibody (mAb) by flow cytometry and ELISA, respectively. Phosphorylation of STAT3, transcription factor essential for chemokines' production and CD44 signal transduction, was determined by Western blotting.

RESULTS

Blocking of CD44H by anti-CD44H mAb on monocytes decreased the engulfment of TMVs and the secretion of CCL4 and CCL5, but had no effect on CCL2, CCL3 and CXCL8. STAT-3 phosphorylation in monocytes incubated with TMVs after CD44 blocking was also reduced.

CONCLUSION

The results suggest that tumour-derived microvesicles (TMVs) may carry bioactive cargo(s) which induces STAT3 dependent signalling pathway in human monocytes via CD44 molecules.

Nrf2-heme oxygenase-1 axis in mucoepidermoid carcinoma of the lung: Antitumoral effects associated with down-regulation of matrix metalloproteinases

Lung mucoepidermoid carcinoma (MEC) is a very poorly characterized rare subtype of non-small-cell lung cancer (NSCLC) associated with more favorable prognoses than other forms of intrathoracic malignancies. We have previously identified that heme oxygenase-1 (HO-1, encoded by HMOX1) inhibits MEC tumor growth and modulates the transcriptome of microRNAs. Here we investigate the role of a major upstream regulator of HO-1 and a master regulator of cellular antioxidant responses, transcription factor Nrf2, in MEC biology. Nrf2 overexpression in the NCI-H292 MEC cell line mimicked the phenotype of HO-1 overexpressing cells, leading to inhibition of cell proliferation and migration and down-regulation of oncogenic miR-378. HMOX1 silencing identified HO-1 as a major mediator of Nrf2 action. Nrf2- and HO-1 overexpressing cells exhibited strongly diminished expression of multiple matrix metalloproteinases and inflammatory cytokine interleukin-1β, which was confirmed in an NCI-HO-1 xenograft model. Overexpression of HO-1 altered not only human MMP levels in tumor cells but also murine MMP levels within tumor microenvironment and metastatic niche. This could possibly contribute to decreased metastasis to the lungs and inhibitory effects of HO-1 on MEC tumor growth. Our profound transcriptome analysis and molecular characterization of the mucoepidermoid lung carcinoma helps to understand the specific clinical presentations of these tumors, emphasizing a unique antitumoral role of the Nrf2-HO-1 axis.

Endothelial precursor cell-based therapy to target the pathologic angiogenesis and compensate tumor hypoxia

Hypoxia-inducing pathologies as cancer develop pathologic and inefficient angiogenesis which rules tumor facilitating microenvironment, a key target for therapy. As such, the putative ability of endothelial precursor cells (EPCs) to specifically home to hypoxic sites of neovascularization prompted to design optimized, site-specific, cell-mediated, drug-/gene-targeting approach. Thus, EPC lines were established from aorta-gonad-mesonephros (AGM) of murine 10.5 dpc and 11.5 dpc embryo when endothelial repertoire is completed. Lines representing early endothelial differentiation steps were selected: MAgEC10.5 and MagEC11.5. Distinct in maturation, they differently express VEGF receptors, VE-cadherin and chemokine/receptors. MAgEC11.5, more differentiated than MAgEC 10.5, displayed faster angiogenesis in vitro, different response to hypoxia and chemokines. Both MAgEC lines cooperated to tube-like formation with mature endothelial cells and invaded tumor spheroids through a vasculogenesis-like process. In vivo, both MAgEC-formed vessels established blood flow. Intravenously injected, both MAgECs invaded Matrigel(TM)-plugs and targeted tumors. Here we show that EPCs (MAgEC11.5) target tumor angiogenesis and allow local overexpression of hypoxia-driven soluble VEGF-receptor2 enabling drastic tumor growth reduction. We propose that such EPCs, able to target tumor angiogenesis, could act as therapeutic gene vehicles to inhibit tumor growth by vessel normalization resulting from tumor hypoxia alleviation.

Regulation and novel action of thymidine phosphorylase in non-small cell lung cancer: crosstalk with Nrf2 and HO-1

Proangiogenic enzyme thymidine phosphorylase (TP) is a promising target for anticancer therapy, yet its action in non-small cell lung carcinoma (NSCLC) is not fully understood. To elucidate its role in NSCLC tumor growth, NCI-H292 lung mucoepidermoid carcinoma cells and endothelial cells were engineered to overexpress TP by viral vector transduction. NSCLC cells with altered expression of transcription factor Nrf2 or its target gene heme oxygenase-1 (HO-1) were used to study the regulation of TP and the findings from pre-clinical models were related to gene expression data from clinical NSCLC specimens. Overexpression of Nrf2 or HO-1 resulted in upregulation of TP in NCI-H292 cells, an effect mimicked by treatment with an antioxidant N-acetylcysteine and partially reversed by HO-1 knockdown. Overexpression of TP attenuated cell proliferation and migration in vitro, but simultaneously enhanced angiogenic potential of cancer cells supplemented with thymidine. The latter was also observed for SK-MES-1 squamous cell carcinoma and NCI-H460 large cell carcinoma cells. TP-overexpressing NCI-H292 tumors in vivo exhibited better oxygenation and higher expression of IL-8, IL-1β and IL-6. TP overexpression in endothelial cells augmented their angiogenic properties which was associated with enhanced generation of HO-1 and VEGF. Correlation of TP with the expression of HO-1 and inflammatory cytokines was confirmed in clinical samples of NSCLC. Altogether, the increased expression of IL-1β and IL-6 together with proangiogenic effects of TP-expressing NSCLC on endothelium can contribute to tumor growth, implying TP as a target for antiangiogenesis in NSCLC.

Interplay between heme oxygenase-1 and miR-378 affects non-small cell lung carcinoma growth, vascularization, and metastasis

AIMS

Heme oxygenase-1 (HO-1, HMOX1) can prevent tumor initiation; while in various tumors, it has been demonstrated to promote growth, angiogenesis, and metastasis. Here, we investigated whether HMOX1 can modulate microRNAs (miRNAs) and regulate human non-small cell lung carcinoma (NSCLC) development.

RESULTS

Stable HMOX1 overexpression in NSCLC NCI-H292 cells up-regulated tumor-suppressive miRNAs, whereas it significantly diminished the expression of oncomirs and angiomirs. The most potently down-regulated was miR-378. HMOX1 also up-regulated p53, down-regulated angiopoietin-1 (Ang-1) and mucin-5AC (MUC5AC), reduced proliferation, migration, and diminished angiogenic potential. Carbon monoxide was a mediator of HMOX1 effects on proliferation, migration, and miR-378 expression. In contrast, stable miR-378 overexpression decreased HMOX1 and p53; while enhanced expression of MUC5AC, vascular endothelial growth factor (VEGF), interleukin-8 (IL-8), and Ang-1, and consequently increased proliferation, migration, and stimulation of endothelial cells. Adenoviral delivery of HMOX1 reversed miR-378 effect on the proliferation and migration of cancer cells. In vivo, HMOX1 overexpressing tumors were smaller, less vascularized and oxygenated, and less metastatic. Overexpression of miR-378 exerted opposite effects. Accordingly, in patients with NSCLC, HMOX1 expression was lower in metastases to lymph nodes than in primary tumors.

INNOVATION AND CONCLUSION

In vitro and in vivo data indicate that the interplay between HMOX1 and miR-378 significantly modulates NSCLC progression and angiogenesis, suggesting miR-378 as a new therapeutic target. REBOUND TRACK: This work was rejected during standard peer review and rescued by Rebound Peer Review (Antioxid Redox Signal 16, 293-296, 2012) with the following serving as open reviewers: James F. George, Mahin D. Maines, Justin C. Mason, and Yasufumi Sato.

Chemokine receptors and chemokine production by CD34+ stem cell-derived monocytes in response to cancer cells

BACKGROUND

The chemokine-chemokine receptor (CR) network is involved in the regulation of cellular infiltration of tumours. Cancer cells and infiltrating macrophages produce a whole range of chemokines. This study explored the expression of some CR and chemokine production by cord blood stem cell-derived CD34(+) monocytes and their novel CD14(++)CD16(+) and CD14(+)CD16(-) subsets in response to tumour cells.

MATERIAL AND METHODS

CR expression was determined by flow cytometry and their functional activity by migration to chemoattractants. Monocytes were cultured with tumour cells and the chemokine content was assessed in culture supernatants.

RESULTS

CD14(++)CD16(+) monocytes exhibited increased expression of chemokine (C-C) receptor (CCR) 1, while CD14(+)CD16(-) of CCR2, chemokine (C-X-C) receptor (CXCR) 1, 2 and 4. The increased expression of CCR2 on CD14(+)CD16(-) monocytes was associated with their enhanced migration to monocyte chemoattractant protein-1 (CCL2), MCP-3 (CCL7), MCP-2 (CCL8) and MCP-4 (CCL13), while that of CXCR1 and 2 to interleukin 8 (CXCL8), and CXCR4 to stromal cell-derived factor-1 (CXCL12). Tumour cells induced production of macrophage inflammatory protein-1α (CCL3) MIP-1β and regulated on activation normal T-cells expressed and secreted (CCL5) but not CCL2 or CXCL8, monokine induced by gamma interferon (CXCL9), interferon gamma-induced protein 10 (CXCL10).

CONCLUSION

The studied monocyte subsets, in comparison to those from blood, exhibit different expression of CRs and response to the stimuli that occur from tumour cells.

Tumour-derived microvesicles contain interleukin-8 and modulate production of chemokines by human monocytes

BACKGROUND

Tumour-derived microvesicles (TMVs) may interact with cells of the immune system. Our previous observations indicated that TMVs modulate production of cytokines and reactive oxygen species (ROS) by monocytes. This study was designed to determine the role of TMVs in stimulation of chemokine production by human monocytes.

MATERIALS AND METHODS

Chemokines at the mRNA and protein level were detected by real-time PCR and by Western blot, respecively. Chemokine release and chemotaxis of blood leukocytes were analysed by flow cytometry. Matrigel assay was used to determine angiogenesis in a NOD-SCID mice model.

RESULTS

TMVs induced secretion of interleukin-8 (CXCL8), monocyte chemoattractant protein-1 (CCL2), macrophage inflammatory protein-1α (CCL3) and MIP-1β (CCL4), and regulated on activation normal T-cells expressed and secreted (CCL5) chemokines and accumulation of their mRNA in monocytes. Moreover, TMVs enhanced angiogenesis in NOD-SCID mice by delivering chemokines and via stimulation of monocytes. In addition, TMVs may be storage for chemokines thus inducing chemotaxis of blood leukocytes.

CONCLUSION

These results further support the role of TMVs in modulation of monocyte biological activity.

Tumour-derived microvesicles (TMV) mimic the effect of tumour cells on monocyte subpopulations

BACKGROUND

Monocytes/macrophages may be affected by tumour cells via cell-to-cell contact, soluble factors and by tumour-derived microvesicles (TMV). Previous observations indicate that TMV interact with monocytes and alter their immunophenotype and activity. This study was designed to determine interactions of TMV with subpopulations (CD14(++)CD16(-) and CD14(+)CD16(++)) of human monocytes.

METHODS

Engulfment of TMV by subsets of monocytes was analysed by flow cytometry. Moreover cytokine release and production of reactive oxygen intermediates (ROI) and reactive nitrogen intermediates (RNI) by CD14(++)CD16(-) and CD14(+)CD16(++) cells after TMV stimulation was determined.

RESULTS

It was found that TMV are engulfed more efficiently by CD14(++)CD16(-) than CD14(+)CD16(++) cells. TMV-activated CD14(++)CD16(-) cells produce more ROI and interleukin -10 (IL-10) than CD14(++)CD16(+). CD14(+)CD16(++) cells following TMV stimulation showed an increased release of tumour necrosis factor alpha, IL-12p40 and RNI.

CONCLUSION

TMV significantly modulate biological activity of monocyte subsets with a pattern similar to tumour cells. Therefore, TMV mimic the activating effect of tumour cells on monocytes as assessed by release of cytokines, ROI and RNI.

Circulating tumour-derived microvesicles in plasma of gastric cancer patients

Cell membrane microfragments called microvesicles (MV) originating from different cells are circulating in the blood of healthy subjects and their elevated numbers are found in different diseases, including cancer. This study was designed to characterise MV present in plasma of gastric cancer patients. Since majority of MV in blood are platelets-derived (PMV), plasma samples deprived of PMV were used. In comparison to control, the number of MV in patients was significantly elevated in all stages, higher in more advanced disease. Patients' MV showed an increased membrane expression of CCR6 and HER-2/neu. The proportion of MV carrying some leucocyte determinants was low and similar in patients and control. Transmission electron microscopy showed their substantial heterogeneity in size and shape. The size determined by dynamic light scattering analysis confirmed this heterogeneity. The MV size distribution in patients was broader within the range of 10-800 nm, while in control MV showed 3-mode distribution within the range of 10-400 nm. Atomic force microscopy confirmed MV size heterogeneity with implication that larger objects represented aggregates of smaller microparticles. Patients' MV exhibited increased absolute values of zeta potential, indicating a higher surface charge. Tumour markers HER-2/neu, MAGE-1, c-MET and EMMPRIN were detected both in control and patients' samples with stronger expression in the latter. Significantly higher expression of MAGE-1 and HER-2/neu mRNA was observed in individual patients. All together, it suggests that at least some MV in plasma of gastric cancer patients are tumour-derived. However, their role in cancer requires further studies.

Tumour-derived microvesicles modulate biological activity of human monocytes

Tumour cells are shedding membrane fragments (tumour-derived microvesicles, TMV) that may interact with cells of immune system. Our previous observations indicated that TMV carry several surface determinants and mRNA of tumour cells and transfer some of them to monocytes. This study determined the effect of TMV on biological activity of human monocytes as the precursors of tumour infiltrating macrophages (TIM). It was found that TMV activated monocytes as shown by an increased HLA-DR expression, induced production of ROI (reactive oxygen intermediates) and of tumour necrosis factor (TNF), interleukin (IL)-10, IL-12p40 accumulation of mRNA and their secretion. Induction of TNF synthesis was CD44 dependent as blocking of CD44 on monocytes abolished its secretion. TMV-treated monocytes showed an increased antitumour activity as judged by enhanced cytotoxicity/cytostasis against tumour cells in vitro. Taken together, these results indicate that TMV significantly modulate biological activity of monocytes and thus mimic the effect of tumour cells on them. This may suggest that tumour cells interact with TIM not only via direct contact, soluble factors, but also TMV.

Expansion and differentiation of CD14+CD16(-) and CD14+ +CD16+ human monocyte subsets from cord blood CD34+ hematopoietic progenitors

To determine whether monocytes can be generated from CD34+ hematopoietic progenitors in large numbers, cord blood CD34+ cells were first expanded for 3-10 days in X-VIVO 10 medium supplemented with FCS, stem cell factor (SCF), thrombopoietin (TPO), and Flt-3 Ligand (Flt-3L), and then differentiated in IMDM medium supplemented with FCS, SCF, Flt-3L, IL-3 and M-CSF for 7-14 days. These two step cultures resulted in up to a 600-fold mean increase of total CD14+ cells. Using this approach, two subpopulations of monocytes were obtained: CD14+CD16(-) and CD14++CD16+ occurring at 2:1 ratio. 1.25(OH)2 Vitamin D3 added to the differentiation medium altered this ratio by decreasing proportion of CD14++CD16+ monocytes. In comparison to CD14+CD16(-), the CD14++CD16+ cells showed different morphology and an enhanced expression of CD11b, CD33, CD40, CD64, CD86, CD163, HLA-DR, and CCR5. Both subpopulations secreted TNF and IL-12p40 but little or no IL-10. CD14++CD16+ monocytes released significantly more IL-12p40, were better stimulators of MLR but showed less S. aureus phagocytosis. These subpopulations are clearly different from those present in the blood and may be novel monocyte subsets that represent different stages in monocyte differentiation with distinct biological function.

Cell survival, cell death and cell cycle pathways are interconnected: implications for cancer therapy

The partial cross-utilization of molecules and pathways involved in opposing processes like cell survival, proliferation and cell death, assures that mutations within one signaling cascade will also affect the other opposite process at least to some extent, thus contributing to homeostatic regulatory circuits. This review highlights some of the connections between opposite-acting pathways. Thus, we discuss the role of cyclins in the apoptotic process, and in the regulation of cell proliferation. CDKs and their inhibitors like the INK4-family (p16(Ink4a), p15(Ink4b), p18(Ink4c), p19(Ink4d)), and the Cip1/Waf1/Kip1-2-family (p21(Cip1/Waf1), p27(Kip1), p57(Kip2)) are shown both in the context of proliferation regulators and as contributors to the apoptotic machinery. Bcl2-family members (i.e. Bcl2, Bcl-X(L) Mcl-1(L); Bax, Bok/Mtd, Bak, and Bcl-X(S); Bad, Bid, Bim(EL), Bmf, Mcl-1(S)) are highlighted both for their apoptosis-regulating capacity and also for their effect on the cell cycle progression. The PI3-K/Akt cell survival pathway is shown as regulator of cell metabolism and cell survival, but examples are also provided where aberrant activity of the pathway may contribute to the induction of apoptosis. Myc/Mad/Max proteins are shown both as a powerful S-phase driving complex and as apoptosis-sensitizers. We also discuss multifunctional proteins like p53 and Rb (RBL1/p107, RBL2/p130) both in the context of G1-S transition and as apoptotic triggers. Finally, we reflect on novel therapeutic approaches that would involve redirecting over-active survival and proliferation pathways towards induction of apoptosis in cancer cells.

Antitumor response of CD14+/CD16+ monocyte subpopulation

OBJECTIVE

Two main subpopulations of human blood monocytes are distinguished on the basis of CD14 and CD16 expression: the major population with enhanced expression of CD14 (CD14++ monocytes) and the minor one with a weak expression of CD14 coexpressing CD16 (CD14+/CD16+ monocytes). As monocytes and macrophages are involved in antitumor response of the host, we assessed the ability of CD14+/CD16+ monocytes to produce cytokines (intracellular expression, release) and reactive oxygen and nitrogen (ROI, RNI) intermediates following stimulation in vitro with tumor cells.

MATERIALS AND METHODS

Monocytes were isolated by elutriation and their subpopulations by FACS sorting. Monocytes and their subpopulations were cocultured with tumor cells. Cytokine (TNF-alpha, IL-12, and IL-10) production was assessed by determination of intracellular protein expression by flow cytometry, and release by ELISA. ROI induction was detected by chemiluminescence and O2- production by flow cytometry, whereas RNI by intracellular expression of inducible NO synthase (iNOS) and nitric oxide (NO) release assessed colorimetrically.

RESULTS

CD14+/CD16+ monocytes stimulated with tumor cells showed significantly enhanced production of TNF-alpha, IL-12p40, IL-12p70 (intracellular expression, release), whereas little IL-10 release was observed. CD14+/CD16+ subpopulation did not produce ROI, but showed an increased iNOS expression and NO release. CD14+/CD16+ monocytes also exhibited enhanced cytotoxic and cytostatic activities against tumor cells.

CONCLUSIONS

CD14+/CD16+ cells constitute the main subpopulation of blood monocytes involved in antitumor response as judged by enhanced production of proinflammatory cytokines, RNI, and increased cytotoxic/cytostatic activity.

Caspase-8 activation precedes alterations of mitochondrial membrane potential during monocyte apoptosis induced by phagocytosis and killing of Staphylococcus aureus

Human peripheral blood monocytes become apoptotic following phagocytosis and killing of Staphylococcus aureus. Although this type of monocyte apoptosis is known to be initiated by Fas-Fas ligand (FasL) interactions, the downstream signaling pathway has not been determined. In this work the involvement of mitochondria and the kinetics of caspase-8 and caspase-3 activation after phagocytosis of S. aureus were studied. Caspase-8 activity was measured in cell lysates by using the fluorogenic substrate Ac-IETD-AFC. Active caspase-3 levels and mitochondrial membrane potential (Deltapsi(m)) were measured in whole cells by flow cytometry using monoclonal antibodies reacting with activated caspase-3 and chloromethyl-X-rosamine, respectively. The results show that caspase-8 was activated shortly after phagocytosis of bacteria. Caspase-8 activation was followed by progressive disruption of Deltapsi(m), which is associated with the production of reactive oxygen intermediates. The irreversible caspase-8 inhibitor zIETD-FMK prevented the disruption of Deltapsi(m) and the release of cytochrome c from S. aureus-exposed monocytes. Caspase-3 activation occurred following disruption of Deltapsi(m). These results strongly suggest that apoptosis of monocytes that have phagocytosed and killed S. aureus is driven by the Fas-FasL-initiated pathway, which is typical for type II cells.

Recognition of apoptotic cells by human peripheral blood monocytes does not alter their ability to phagocytize and kill Staphylococcus aureus

INTRODUCTION

During acute inflammation, leukocyte infiltration is mostly neutrophilic, but later monocytes prevail. The majority of inflammatory cells, particularly neutrophilic polymorphonuclear leukocytes (PMNs), become apoptotic at later stages of inflammation and are phagocytosed by neighboring cells, mostly by macrophages. Recently, it has been found that human peripheral blood monocytes also recognize apoptotic cells, which primes them to increased production of interleukin (IL)-10--a cytokine known to reduce phagocytes' ability to engulf and kill pathogens. Based on the above, we studied monocytes' ability to phagocytose and kill Staphylococcus aureus while in contact with apoptotic cells.

MATERIALS AND METHODS

Monocytes isolated by elutriation were co-cultured with apoptotic PMNs or Jurkat cells and exposed to viable, human serum-opsonized S. aureus. To induce apoptosis PMNs were cultured overnight while Jurkat cells were UV-treated. Apoptosis, phagocytosis of bacteria and intracellular superoxide production were measured by flow cytometry. Production of reactive oxygen species was also followed by measurement of chemiluminescence. The bactericidal effect was determined by standard colony forming units method.

RESULTS

Data presented show that contact of monocytes with apoptotic neutrophils and Jurkat cells had no influence on monocyte phagocytosis of S. aureus, the generation of reactive oxygen species, or the killing of bacteria.

CONCLUSION

The data obtained suggest that monocytes attracted to the inflammatory site are not deficient in their ability to cope with pathogens after contact with apoptotic cells despite increased production of IL-10.

Fas (CD95)-Fas ligand interactions are responsible for monocyte apoptosis occurring as a result of phagocytosis and killing of Staphylococcus aureus

Human peripheral blood monocytes become apoptotic following phagocytosis of Staphylococcus aureus. In this study, we investigated the mechanisms involved in this phenomenon. Cells exposed to bacteria were examined for the surface expression of Fas and Fas ligand (FasL). The level of soluble form of FasL was also measured in the culture supernatants. As Fas-mediated apoptosis involves the activation of caspases, the activities of caspase-8 and caspase-3 were determined. Finally, the involvement of oxidative stress in apoptosis of infected monocytes was investigated. The data indicated that as a consequence of phagocytosis of S. aureus, FasL is released from the monocyte surface and induces apoptosis of phagocytic monocytes and to some extent the bystander cells. The importance of this mechanism was confirmed by demonstrating that blockage of CD95 prevents S. aureus-induced apoptosis of monocytes. Cell death occurring after phagocytosis of S. aureus involves the activation of caspase-3-like proteases, as the specific caspase-3 inhibitor suppressed apoptosis of infected cells. The generation of reactive oxygen intermediates by phagocytic monocytes by itself is not sufficient as a death signal but rather acts in up-regulating FasL shedding and possibly in modulating caspase activity.