Philipp J. Hohensinner

Oxidized Phospholipids Stimulate Angiogenesis Via Autocrine Mechanisms, Implicating a Novel Role for Lipid Oxidation in the Evolution of Atherosclerotic Lesions

Angiogenesis is a common feature observed in advanced atherosclerotic lesions. We hypothesized that oxidized phospholipids (OxPLs), which accumulate in atherosclerotic vessels can stimulate angiogenesis. We found that oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine (OxPAPC) stimulated the formation of sprouts from endothelial cell spheroids and promoted growth of capillaries into Matrigel plugs in mice. OxPLs stimulated expression of vascular endothelial growth factor (VEGF) in vivo and in several normal and tumor cell types in vitro. In addition, OxPAPC upregulated cyclooxygenase (COX)-2 and interleukin (IL)-8. COX-2 inhibitors, as well as blocking antibodies to IL-8 suppressed activation of sprouting by OxPAPC. We conclude that OxPAPC stimulates angiogenesis via autocrine mechanisms involving VEGF, IL-8, and COX-2–generated prostanoids. Our data suggest that accumulation of OxPLs may contribute to increased growth of blood capillaries in advanced lesions, thus leading to progression and destabilization of atherosclerotic plaques.

Prognostic value of apoptosis markers in advanced heart failure patients

AIMS Apoptosis plays an important role in the progression of heart failure (HF). The purpose of this study was to assess whether the pro-apoptotic molecules apoptosis-stimulating fragment (FAS, CD95/APO-1) and tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) predict event-free survival of HF patients. METHODS AND RESULTS We assayed soluble (s)FAS and sTRAIL levels in 351 patients with advanced HF. During the median follow-up time of 16 months, 175 patients (50%) experienced the composite endpoints: rehospitalization and death. The hazard increased with sFAS concentrations, with a hazard ratio of 2.3 comparing fourth and first quartiles. This association remained significant after adjustment for B-type natriuretic peptide (BNP) and other risk factors in a Cox regression model (P = 0.014). Patients with high sFAS but low BNP had a comparable event-free survival rate with those with elevated BNP only (P = 0.78). Conversely, high sTRAIL concentrations were related to a better prognosis. Particularly, the risk of mortality dropped by 70% in the fourth quartile of sTRAIL (P = 0.001, multivariable Cox regression model). CONCLUSION sFAS is an independent risk predictor in advanced HF patients. It may be of particular value for the identification of high-risk patients in addition to BNP. Conversely, sTRAIL appears to be protective and could be an interesting therapeutic agent.

Vascular Endothelial Growth Factor Is Induced by the Inflammatory Cytokines Interleukin-6 and Oncostatin M in Human Adipose Tissue In Vitro and in Murine Adipose Tissue In Vivo

Objectives—It is believed that adipose tissue acts as an endocrine organ by producing inflammatory mediators and thereby contributes to the increased cardiovascular risk seen in obesity. A link between adipose tissue mass and angiogenesis has been suggested. Vascular endothelial growth factor (VEGF) seems to be implicated in this process. Members of the glycoprotein (gp)130 ligand family regulate VEGF expression in other cells. Methods and Results—We used tissue explants as well as primary cultures of preadipocytes and adipocytes from human subcutaneous and visceral adipose tissue to investigate whether the gp130 ligands oncostatin M (OSM), interleukin-6 (IL-6), leukemia inhibitory factor (LIF), and cardiotrophin-1 (CT-1) regulate VEGF expression in human adipose tissue. Human subcutaneous and visceral adipose tissue responded to treatment with IL-6 and OSM with a significant increase in VEGF production. Human preadipocytes were isolated from subcutaneous and visceral adipose tissue. Adipocyte-differentiation was induced by hormone-supplementation. All cell types responded to IL-6 and OSM with a robust increase in VEGF protein production and a similar increase in VEGF-specific mRNA. Furthermore, IL-1&bgr; synergistically enhanced the effect of OSM on VEGF production. AG-490, a JAK/STAT inhibitor, abolished the OSM-dependent VEGF induction almost completely. In mice, IL-6 and OSM increased serum levels of VEGF and VEGF mRNA and vessel density in adipose tissue. Conclusion—We speculate that the inflammatory cytokines IL-6 and OSM might support angiogenesis during adipose tissue growth by upregulating VEGF.

Oncostatin M-enhanced vascular endothelial growth factor expression in human vascular smooth muscle cells involves PI3K-, p38 MAPK-, Erk1/2- and STAT1/STAT3-dependent pathways and is attenuated by interferon-γ

The pleiotropic cytokine oncostatin M (OSM), a member of the glycoprotein (gp)130 ligand family, plays a key role in inflammation and cardiovascular disease. As inflammation precedes and accompanies pathological angiogenesis, we investigated the effect of OSM and other gp130 ligands on vascular endothelial growth factor (VEGF) production in human vascular smooth muscle cells (SMC). Human coronary artery SMC (HCASMC) and human aortic SMC (HASMC) were treated with different gp130 ligands. VEGF protein was determined by ELISA. Specific mRNA was detected by RT-PCR. Western blotting was performed for signal transducers and activators of transcription1 (STAT1), STAT3, Akt and p38 mitogen-activated protein kinase (p38 MAPK). OSM mRNA and VEGF mRNA expression was analyzed in human carotid endaterectomy specimens from 15 patients. OSM increased VEGF production in both HCASMC and HASMC derived from different donors. OSM upregulated VEGF and OSM receptor-specific mRNA in these cells. STAT3 inhibitor WP1066, p38 MAPK inhibitors SB-202190 and BIRB 0796, extracellular signal-regulated kinase1/2 (Erk1/2) inhibitor U0126, and phosphatidylinositol 3-kinase (PI3K) inhibitors LY-294002 and PI-103 reduced OSM-induced VEGF synthesis. We found OSM expression in human atherosclerotic lesions where OSM mRNA correlated with VEGF mRNA expression. Interferon-γ (IFN-γ), but not IL-4 or IL-10, reduced OSM-induced VEGF production in vascular SMC. Our findings that OSM, which is present in human atherosclerotic lesions and correlates with VEGF expression, stimulates production of VEGF by human coronary artery and aortic SMC indicate that OSM could contribute to plaque angiogenesis and destabilization. IFN-γ reduced OSM-induced VEGF production by vascular SMC.

Inflammation and Cardiac Outcome

Purpose of review Inflammation is a key component in cardiovascular disease. Controlling inflammatory events and their subsequent processes holds the potential for novel therapeutic treatment options. Cytokines are the propagators of inflammation. In this review we will discuss important cytokines including IL-6, TNF-α, MCP-1, fractalkine, M-CSF and GDF-15, and their effect on cardiac outcome. Recent findings Recent studies have shed light on the role of IL-6 in cardiovascular disease. Long-term IL-6 levels are highly associated with coronary heart disease. Molecular studies indicate that a permanent prolongation of STAT signaling in cardiac myocytes might be a potential reason for the detrimental effects of IL-6. TNF-α was long considered to have detrimental effects on myocardial function but recent studies show cardioprotective mechanisms for TNF-α. Macrophage modulating cytokines emerge as interesting molecular targets to treat cardiovascular disease. Especially, the two different subtypes of monocytes, a pro-inflammatory and a reparative subset, and their different chemotactic properties might be possible drug targets. Finally, we discuss GDF-15, which emerges as a novel biomarker in cardiovascular disease reflecting information from several pathological pathways. Summary Cytokines are the main proximal mediators of inflammation and hold the potential of being good molecular targets for novel treatment regimes. Cytokines might be valuable biomarkers, adding information about the pathologic pathways in cardiovascular disease.

A multi-biomarker risk score improves prediction of long-term mortality in patients with advanced heart failure

BACKGROUND Accurate risk prediction is important for an adequate management of heart failure (HF) patients. We assessed the incremental prognostic ability of a multi-biomarker approach in advanced HF. METHODS In 349 patients with advanced HF (median 75 years, 66% male) we investigated the incremental prognostic value of 12 novel biomarkers involved in different pathophysiological pathways including inflammation, immunological activation, oxidative stress, cell growth, remodeling, angiogenesis and apoptosis. RESULTS During a median follow-up of 4.9 years 55.9% of patients died. Using multivariable Cox regression and bootstrap variable-selection age, chronic obstructive pulmonary disease, N-terminal pro-B-type natriuretic peptide (NT-proBNP) and the following 5 novel biomarkers were retained in the best mortality prediction model: the chemokine fractalkine, the angiogenic and mitogenic hepatocyte growth factor (HGF), the growth differentiation factor 15 (GDF-15) influencing cardiac remodeling and apoptosis, and the 2 pro-apoptotic molecules soluble apoptosis-stimulating fragment (sFAS) and soluble tumor necrosis factor-related apoptosis-inducing ligand (sTRAIL). This multi-biomarker score had strong discriminatory power for 5-year mortality (area under the Receiver Operating Characteristic curve [AUC]=0.81) and improved risk prediction beyond the prognostic power of a comprehensive conventional risk score including known clinical predictors and NT-proBNP (AUC=0.77). Net reclassification confirmed a significant improvement of individual risk prediction (p=0.003). CONCLUSIONS Risk prediction by a multi-biomarker score is superior to a conventional risk score including clinical parameters and NT-proBNP. Additional predictive information from different biological pathways reflects the multisystemic character of HF.

The anti-angiogenic factor PEDF is present in the human heart and is regulated by anoxia in cardiac myocytes and fibroblasts

Cardiac diseases such as myocardial infarction and heart failure are among the leading causes of death in western societies. Therapeutic angiogenesis has been suggested as a concept to combat these diseases. The biology of angiogenic factors expressed in the heart such as vascular endothelial growth factor (VEGF) is well studied, whereas data on anti‐angiogenic mediators in the heart are scarce. Here we study the expression of the anti‐angiogenic factor pigment epithelium‐derived factor (PEDF) in the human heart and in human cardiac cells. PEDF expression could be detected in human cardiac tissue on the protein and mRNA levels. PEDF mRNA levels were significantly lower in explanted human ischemic hearts as compared to healthy hearts. Our in vitro experiments showed that human adult cardiac myocytes and fibroblasts constitutively secrete PEDF. In addition to anoxic conditions, cobalt chloride, 2,2′dipyridyl and dimethoxally glycine, which stabilize hypoxia inducible factor‐α decreased PEDF expression. Furthermore we show that PEDF inhibits VEGF‐induced sprouting. We have identified PEDF in healthy and ischemic human hearts and we show that PEDF expression is down‐regulated by low oxygen levels. Therefore, we suggest a role for PEDF in the regulation of angiogenesis in the heart and propose PEDF as a possible therapeutic target in heart disease.

The inflammatory mediator oncostatin M induces angiopoietin 2 expression in endothelial cells in vitro and in vivo

Summary.  Objectives: Members of the glycoprotein 130 (gp130) receptor–gp130 ligand family play a role in angiogenesis in different tissues. We tested the effect of this cytokine family on the angiopoietin (Ang)–Tie system, which is involved in blood vessel maturation, stabilization, and regression. Results: Oncostatin M (OSM) increased Ang2 expression in human umbilical vein endothelial cells via Janus kinase/signal transducer and activator of transcription (JAK/STAT) and mitogen‐activated protein (MAP) kinase activation. Furthermore, OSM induced Ang2 expression in macrovascular endothelial cells isolated from the human aorta and in microvascular endothelial cells isolated from human heart. Our in vivo experiments revealed that mRNA expression of Ang2 in hearts of mice injected with OSM increased significantly, and levels of OSM mRNA significantly correlated with mRNA levels of Ang2 in human hearts. In addition, OSM increased the expression of its own receptors, gp130 and OSM receptor, in endothelial cells in vitro and in mice in vivo, and levels of OSM mRNA significantly correlated with mRNA levels of gp130 and OSM receptor in human hearts. Conclusion: Our data, showing the effects of OSM on the Ang–Tie system in endothelial cells, in hearts of mice, and in human heart tissue, provide yet another link between inflammation and angiogenesis.

Differences in the predictive value of tumor necrosis factor-like weak inducer of apoptosis (TWEAK) in advanced ischemic and non-ischemic heart failure

OBJECTIVE To assess the prognostic value of the pro-apoptotic, but also cell growth-inducing molecule soluble tumor necrosis factor-like weak inducer of apoptosis (sTWEAK) in heart failure (HF). METHODS We assayed sTWEAK levels in 351 patients with advanced HF (non-ischemic: 130, ischemic: 221). During a median follow-up of 4.9 years, 195 patients (56%) died. RESULTS sTWEAK concentrations were associated with extended survival in patients with non-ischemic (P=0.022), but not with ischemic HF (P=0.82). The inverse association in non-ischemic HF remained significant in a multivariable Cox regression model (P=0.025) with a hazard ratio of 0.40 (95% confidence interval: 0.21-0.77) comparing the third to the first tertile (P=0.007). CONCLUSION Low sTWEAK levels independently predict mortality in advanced non-ischemic HF. sTWEAK-induced proliferation of cardiomyocytes may explain its impact on suvival. The different prognostic value of sTWEAK in ischemic and non-ischemic HF may point towards distinct pathogenic pathways determining the course of disease.

Fractalkine is an independent predictor of mortality in patients with advanced heart failure

Immunological processes are implicated in the multifactorial pathophysiology of heart failure (HF). The multifunctional chemokine fractalkine (CX3CL1) promotes the extravasation of cytotoxic lymphocytes into tissues. We aimed to assess the prognostic value of fractalkine in HF. Fractalkine plasma levels were determined in 349 patients with advanced systolic HF (median 75 years, 66% male). During a median follow-up of 4.9 years (interquartile range: 4.6-5.2), 55.9% of patients died. Fractalkine was a significant predictor of all-cause mortality (p<0.001) with a hazard ratio of 2.78 (95% confidence interval: 1.95-3.95) for the third compared to the first tertile. This association remained significant after multivariable adjustment for demographics, clinical predictive variables and N-terminal pro-B-type natriuretic peptide (NT-proBNP, p=0.008). The predictive value of fractalkine did not significantly differ between patients with ischaemic and non-ischaemic HF aetiology (p=0.79). The predictive value of fractalkine tertiles was not significantly modified by tertiles of NT-proBNP (p=0.18) but was more pronounced in the first and third tertile of NT-proBNP. Fractalkine was also an independent predictor of cardiovascular mortality (p=0.015). Fractalkine levels were significantly lower in patients on angiotensin-converting enzyme inhibitor therapy (p<0.001). In conclusion, circulating fractalkine with its pro-inflammatory and immunomodulatory effects is an independent predictor of mortality in advanced HF patients. Fractalkine improves risk prediction beyond NT-proBNP and might therefore help to identify high risk patients who need special care. Our data indicate the implication of immune modulation in HF pathology.