Comparison of mechanical support with Impella or extracorporeal life support in post-cardiac arrest cardiogenic shock: a propensity scoring matching analysis

Background

Out of hospital cardiac arrest (OHCA) is a major public health problem and a leading cause of death in industrialized nations. Post-cardiac arrest cardiogenic shock (CS) occurs frequently after resuscitation from CA and may lead to multi-organ failure and death, even in patients with good neurologic prognosis. Mechanical circulatory support (MCS) may be considered at that time in order to augment cardiac output, stabilize hemodynamics and ensure adequate organ perfusion. However, optimal selection of the device type remains unclear and, so far, no specific guideline recommendation exists. The Impella pump and extracorporeal circulatory support (ECLS) are the most frequently used device types for temporary percutaneous MCS in this context.

Purpose

Our aim was to compare outcomes of Impella with extracorporeal life support (ECLS) in patients with post-cardiac arrest cardiogenic shock (CS) complicating acute myocardial infarction (AMI).

Methods

Reetrospective study of patients resuscitated from OHCA with post-cardiac arrest CS following AMI (May 2015 to May 2020) treated with MCS in terms of Impella or ECLS. Outcomes were compared using propensity score-matched analysis to account for differences in baseline characteristics between groups of MCS.

Results

159 patients were included (Impella, n=105; ECLS, n=54). Hospital and 12-month survival rates were comparable in the Impella and the ECLS group (p=0.16 and p=0.3, respectively). After adjustment for baseline differences, both groups demonstrated comparable hospital and 12-month survival (p=0.36 and p=0.64, respectively) (Figure 1). Impella patients had a significantly greater left ventricle ejection-fraction (LVEF) improvement at 96 hours (p<0.01 vs p=0.44 in ECLS) and significantly fewer device-associated complications than ECLS patients (15.2% versus 35.2%, p<0.01 for relevant access site bleeding, 7.6% versus 20.4%, p=0.04 for limb ischemia requiring intervention). In subgroup analyses, Impella was associated with better survival in patients with lower-risk features (lactate <8,6 mmol/L, time from collapse to return of spontaneous circulation <28 min, vasoactive score <46 and Horowitz index >182) (Figure 2).

Conclusions

In the biggest so far homogenous study of OHCA, the use of Impella 2.5/CP or ECLS in post-cardiac arrest CS after AMI was associated with comparable adjusted hospital and 12-month survival. Impella patients had a greater LVEF improvement than ECLS patients, while it was associated with a better survival in patients with low risk profile after OHCA. Device-related access-site complications occurred more frequently in patients with ECLS than Impella support.

Funding Acknowledgement

Type of funding sources: None.

The MARPELLA risk score for prediction of mortality in all-cause refractory cardiogenic shock treated with microaxial transvalvular pump: the MARPELLA study

Background

Although Impella may serve as an alternative strategy in order to stabilize the heart function without the detrimental effects of catecholamines or to bridge the patients in definite therapies in the setting of cardiogenic shock (CS), leading to a widespread use of this device, data concerning reliable prediction or predefining which patients would benefit from the implantation of such a device are completely lacking.

Purpose

To evaluate and to compare the prognostic accuracy of the Acute-Physiology-And-Chronic-Health II (APACHE II), the Simplified-Acute-Physiology-Score II (SAPS II), the Sepsis-related-organ-failure-assessment (SOFA), the intra-aortic-balloon-pump (IABP), the CardShock Score in refractory CS treated with Impella 2.5/CP. Moreover, we aimed to assess the prediction-of-Cardiogenic-shock-Outcome-foR-AMI-patients-salvaGed by VA-ECMO (ENCOURAGE) and the Survival-after -Veno-Arterial-extracorporeal-membranoxygenation (VA-ECMO) (SAVE) score, though initially for VA-ECMO patients created, in patients with CS as well as to develop a new prognostic score in this setting.

Methods

Single center study of consecutive Impella patients with CS admitted to Cardiology department of our university, from February 2013 until December 2020.

Results

A total of 401 patients were included in the analysis. 31% of the patients were supported with Impella CP, whereas 153 (38,1%) patients were resuscitated prior admission. Causes of CS was acute myocardial infarction in 311 (77,5%) patients, followed by dilatative cardiomyopathy/myocarditis (11,1%) and aortic stenosis (6%). The expected mortality according to scores was: SOFA 50%, SAPS II 70%, IABP Shock 55%, CardShock 60%, APACHE II 65%, ENCOURAGE 75% and SAVE score 70%. We observed a survival of 48,9% on hospital discharge and 45,6% after 12 months follow-up. Among the traditional scores estimated, the ENCOURAGE score was the most effective predictive model of mortality outcome presenting a moderate area under curve (AUC) of 0.72, followed by the CardShock, which derived an AUC of 0,7. The SAPS II, SOFA, IABP and the SAVE scores failed to predict outcome in this setting. According to the main predictors of outcome in our population derived from univariate analysis (vasoactive score >31, lactate>4,7 mmol/l, pH<7,31, Creatinine>1,33 mg/dl, Horowitz Index<238, age>71 years and prior resuscitation) as well as the odds ratio derived from binary regression analysis on mortality, a new score, the MARPELLA score, was created. This score reached an AUC of 0.83 (Figure 1). A mortality of 37%, 62% and 83,2% was observed in the low-, intermediate and high-risk group of the MARPELLA score, respectively (Figure 2).

Conclusion

MARPELLA Score is a new more potent score in the setting of all-cause CS that may guide clinicians to optimize the therapy in this group of patients, outweighing the traditional CS and intensive care unit scores.

Funding Acknowledgement

Type of funding sources: None.

Case Report: Arterial Wall Inflammation in Atherosclerotic Cardiovascular Disease is Reduced by Olamkicept (sgp130Fc)

Inflammation is a strong driver of atherosclerotic cardiovascular disease (ASCVD). There is a large unmet need for therapies that prevent or reduce excessive inflammation while avoiding systemic immunosuppression. We showed previously that selective inhibition of pro-inflammatory interleukin-6 (IL-6) trans-signalling by the fusion protein olamkicept (sgp130Fc) prevented and reduced experimental murine atherosclerosis in low-density lipoprotein receptor-deficient (Ldlr^−/−) mice on a high-fat, high-cholesterol diet independently of low-density lipoprotein (LDL) cholesterol metabolism. Therefore, we allowed compassionate use of olamkicept (600 mg intravenously biweekly for 10 weeks) in a patient with very-high-risk ASCVD. Despite optimal LDL cholesterol under maximum tolerated lipid-lowering treatment, the patient had a remaining very high risk for future cardiovascular events related to significant arterial wall inflammation with lipoprotein (a) [Lp(a)]-cholesterol as the main contributor. ¹⁸Fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸FDG PET/CT) measurements were performed before and after the treatment period. Olamkicept reduced arterial wall inflammation in this patient without interfering with lipoprotein metabolism. No clinical or laboratory side effects were observed during or after treatment with olamkicept. Our findings in this patient matched the results from our mechanistic study in Ldlr^−/− mice, which were extended by additional analyses on vascular inflammation. Olamkicept may be a promising option for treating ASCVD independently of LDL cholesterol metabolism. A Phase II trial of olamkicept in ASCVD is currently being prepared.

Left Ventricle Architecture and Valvular Integrity Following Microaxial Mechanical Support: A Two-Year Follow-Up Study

Although the use of microaxilar mechanical circulatory support systems may improve the outcome of patients with cardiogenic shock (CS), little is known about its effect on the long-term structural integrity of left ventricular (LV) valves as well as on the development of LV-architecture. Therefore, we aimed to study the integrity of the LV valves and architecture and function after Impella support. Thus, 84 consecutive patients were monitored over two years having received Impella^TM CP (n = 24) or 2.5 (n = 60) for refractory CS (n = 62) or for high-risk percutaneous coronary interventions (n = 22) followed by optimal medical treatment. Beside a significant increase in LV ejection fraction after two years (p ≤ 0.03 vs. pre-implantation), we observed a statistically significant decrease in LV dilation (p < 0.001) and severity of mitral valve regurgitation (p = 0.007) in the two-year follow-up period, suggesting an improved LV architecture. Neither the duration of support, nor the size of the Impella device or the indication for its use revealed any devastating impact on aortic or mitral valve integrity. These findings indicate that Impella device is a safe means of support of LV-function without detrimental long-term effects on the structural integrity of LV valves regardless of the size of the device or the indication of support.

Left ventricle unloading and valvular integrity following microaxial mechanical circulatory support: a two year follow-up study

Background

Although the use of mechanical circulatory support (MCS) systems may improve the outcome of patients with cardiogenic shock (CS) due to myocardial infarction, little is known about its effect on the long-term structural integrity of left-ventricular (LV) valves as well as on the development of LV- architecture.

Methods

84 consecutive patients were monitored over 2 years having received microaxillar MCS device (ImpellaTM CP or 2.5) for complete coronary revascularization followed by optimal medical treatment.

Results

62 patients were treated for severe cardiogenic shock and compared with 22 patients receiving short-term microaxillar MCS for high risk percutaneous coronary interventions (PCI). 24 patients of the total population received Impella CP (14F motor pump) and the remaining 60 patients received Impella 2.5 (12F motor pump). Beside a significant increase in LV-ejection fraction after 2 years (p≤0.03 vs. pre implantation) in total cohort, we observed a statistically significant decrease in LV-dilation (p&lt;0.001) and the severity of mitral valve regurgitation (p=0.007) in the 2 year follow-up period suggesting an improved LV-architecture. Neither the duration of support, nor the size of the MCS device or the indication for its use revealed any devastating impact on aortic or mitral valve integrity.

Conclusions

These findings indicate that beside complete revascularization and optimal medical treatment, microaxillar transvalvular MCS device supports the restoration of LV-architecture without detrimental long-term effects on the structural integrity of LV valves regardless of the size of the device or the duration of support.

Funding Acknowledgement

Type of funding source: None

Deficiency of Nucleotide-binding oligomerization domain-containing proteins (NOD) 1 and 2 reduces atherosclerosis

Atherosclerosis is crucially fueled by inflammatory pathways including pattern recognition receptor (PRR)-related signaling of the innate immune system. Currently, the impact of the cytoplasmic PRRs nucleotide-binding oligomerization domain-containing protein (NOD) 1 and 2 is incompletely characterized. We, therefore, generated Nod1/Nod2 double knockout mice on a low-density lipoprotein receptor (Ldlr)-deficient background (= Ldlr^−/−Nod1/2^−/−) which were subsequently analyzed regarding experimental atherosclerosis, lipid metabolism, insulin resistance and gut microbiota composition. Compared to Ldlr^−/− mice, Ldlr^−/−Nod1/2^−/− mice showed reduced plasma lipids and increased hepatic expression of the scavenger receptor LDL receptor-related protein 1 after feeding a high-fat diet for 12 weeks. Furthermore, intestinal cholesterol and its bacterial degradation product coprostanol were elevated in Ldlr^−/−Nod1/2^−/− mice, correlating with the increased abundance of Eubacterium coprostanoligenes as assessed by 3rd generation sequencing of the gut microbiota. Atherosclerotic plaques of Ldlr^−/−Nod1/2^−/− mice exhibited less lipid deposition and macrophage accumulation. Moreover, macrophages from Ldlr^−/−Nod1/2^−/− mice showed higher expression of the cholesterol efflux transporters Abca1 and Abcg1 and accordingly reduced foam cell formation. Deficiency of Nod1 and Nod2 led to reduced plaque lipid deposition and inflammatory cell infiltration in atherosclerotic plaques. This might be explained by diminished plasma lipid levels and foam cell formation due to altered expression of key regulators of the hepatic cholesterol pathway as well as differential intestinal cholesterol metabolism and microbiota composition.

Identification of microRNAs involved in NOD-dependent induction of pro-inflammatory genes in pulmonary endothelial cells

The nucleotide-binding oligomerization domain-containing proteins (NOD) 1 and 2 are mammalian cytosolic pattern recognition receptors sensing bacterial peptidoglycan fragments in order to initiate cytokine expression and pathogen host defense. Since endothelial cells are relevant cells for pathogen recognition at the blood/tissue interface, we here analyzed the role of NOD1- and NOD2-dependently expressed microRNAs (miRNAs, miR) for cytokine regulation in murine pulmonary endothelial cells. The induction of inflammatory cytokines in response to NOD1 and NOD2 was confirmed by increased expression of tumour necrosis factor (Tnf)-α and interleukin (Il)-6. MiRNA expression profiling revealed NOD1- and NOD2-dependently regulated miRNA candidates, of which miR-147-3p, miR-200a-3p, and miR-298-5p were subsequently validated in pulmonary endothelial cells isolated from Nod1/2-deficient mice. Analysis of the two down-regulated candidates miR-147-3p and miR-298-5p revealed predicted binding sites in the 3' untranslated region (UTR) of the murine Tnf-α and Il-6 mRNA. Consequently, transfection of endothelial cells with miRNA mimics decreased Tnf-α and Il-6 mRNA levels. Finally, a novel direct interaction of miR-298-5p with the 3' UTR of the Il-6 mRNA was uncovered by luciferase reporter assays. We here identified a mechanism of miRNA-down-regulation by NOD stimulation thereby enabling the induction of inflammatory gene expression in endothelial cells.

Anti-tumor necrosis factor-α therapy increases plaque burden in a mouse model of experimental atherosclerosis

BACKGROUND AND AIMS

Atherosclerosis is critically fueled by vascular inflammation through oxidized lipids and inflammatory cytokines such as tumor necrosis factor (TNF)-α. Genetic disruption of Tnf-α reduces atherosclerosis in experimental mouse models. However, less is known about the therapeutic potential of Tnf-α blockage by pharmacological inhibitors such as monoclonal antibodies, which are already approved for several inflammatory disorders in patients. Therefore, we investigated the effect of pharmacological TNF-α inhibition on plaque development in experimental atherosclerosis.

RESULTS

10 week old male Ldlr^-/- mice were divided into 4 groups (n = 7-10) and fed a high fat, high cholesterol diet for 6 and 12 weeks. Simultaneously, the mouse-specific anti-Tnf-α monoclonal antibody CNTO5048 (CNT) or a control IgG was administered.

RESULTS

CNT reduced circulating inflammatory markers without affecting body weight and glucose metabolism. Unexpectedly, CNT treatment increased plasma triglyceride levels and pro-atherogenic very-low-density lipoprotein (VLDL) cholesterol as well as plaque burden in the thoracoabdominal aorta and in the aortic root. In addition, we observed decreased smooth muscle cell content in the lesions and a trend towards reduced collagen deposition upon Tnf-α inhibition. Furthermore, inflammatory gene expression in the aortic arch was increased following Tnf-α inhibitor treatment.

CONCLUSIONS

Although up to 12-week pharmacological inhibition of TNF-α in Ldlr^-/- mice diminishes systemic inflammation, experimental plaque burden and vascular inflammatory gene expression are increased, while markers of plaque stability decrease. These observations may be explained by the development of a pro-atherogenic plasma lipid profile.

NADPH oxidase NOX2 mediates TLR2/6-dependent release of GM-CSF from endothelial cells

NADPH oxidase-generated reactive oxygen species (ROS) from immune cells are well known to be important for pathogen killing in response to TLR ligands. Here, we investigated a new aspect of NADPH oxidase in the TLR2/6-induced release of the immunologically relevant GM-CSF by endothelial cells. Stimulation of human endothelial cells with TLR2/6 agonist, MALP-2 (macrophage-activating lipopeptide of 2 kDa), induced NADPH oxidase activation and ROS formation. Inhibition by ROS scavengers and NADPH oxidase inhibitors blocked MALP-2-induced GM-CSF release. NADPH oxidase activators or ROS donors alone did not result in GM-CSF secretion; however, additional superoxide supply augmented MALP-2-induced GM-CSF secretion and restored GM-CSF levels after NADPH oxidase inhibition. MALP-2-dependent NF-ĸB activation was suppressed by NADPH oxidase inhibition, and inhibition of NF-κB completely blunted MALP-2-induced GM-CSF release. Vascular explants from mice that were deficient for the NADPH oxidase subunit p47 ^phox showed diminished intimal superoxide production and GM-CSF release after ex vivo stimulation with MALP-2. Moreover, an increase in circulating progenitor cells after MALP-2 injection was completely abolished in p47^phox-knockout mice. Finally, MALP-2 stimulation increased mRNA expression of the major subunit NADPH oxidase, (Nox)2, in endothelial cells, and Nox2 inhibition prevented MALP-2-induced GM-CSF release. Our findings identify a Nox2-containing NADPH oxidase as a crucial regulator of the immunologic important growth factor GM-CSF after TLR2/6 stimulation in endothelial cells.-Schuett, J., Schuett, H., Oberoi, R., Koch, A.-K., Pretzer, S., Luchtefeld, M., Schieffer, B., Grote, K. NADPH oxidase NOX2 mediates TLR2/6-dependent release of GM-CSF from endothelial cells.

Targeting Tumor Necrosis Factor-α with Adalimumab: Effects on Endothelial Activation and Monocyte Adhesion

OBJECTIVE

It is well known that atherosclerotic inflammatory vascular disease is critically driven by oxidized lipids and cytokines. In this regard, tumor necrosis factor (TNF)-α is known as a crucial mediator of early pro-atherosclerotic events. Epidemiologic data suggest that blockade of TNF-α has beneficial effects on vascular outcomes in patients with rheumatoid arthritis, however, detailed mechanistic studies are still lacking. This study aims to elucidate effects of TNF-α blockade by adalimumab-which is approved for several inflammatory disorders-on endothelial activation and monocyte adhesion under pro-atherosclerotic conditions.

METHODS AND RESULTS

Phorbol myristate acetate (PMA) differentiated THP-1 macrophages were stimulated with oxidized low density lipoprotein and subsequent analysis of this conditioned media (oxLDL CM) revealed a strong release of TNF-α. The TNF-α rich supernatant led to activation of human umbilical vein endothelial cells (HUVEC) as shown by enhanced expression of major adhesion molecules, such as vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1) and E-selectin which was suppressed by the TNF-α inhibitor adalimumab. Accordingly, adalimumab effectively prevented THP-1 monocyte adhesion to endothelial cells under static as well as under flow conditions. Furthermore, adalimumab suppressed endothelial leakage as shown by Evan's blue diffusion across a confluent endothelial monolayer. Of note, after intraperitoneal injection we detected abundant deposition of fluorophore-labelled adalimumab in atherosclerotic plaques of hypercholesterolemic mice.

CONCLUSION

Our results show that adalimumab prevents major inflammatory effects of TNF-α on endothelial activation, endothelial monocyte adhesion, endothelial leakage and therefore extends the therapeutic options of adalimumab to limit vascular inflammation.

Lipocalin (LCN) 2 Mediates Pro-Atherosclerotic Processes and Is Elevated in Patients with Coronary Artery Disease

Background

Lipocalin (LCN) 2 is associated with multiple acute and chronic inflammatory diseases but the underlying molecular and cellular mechanisms remain unclear. Here, we investigated whether LCN2 is released from macrophages and contributes to pro-atherosclerotic processes and whether LCN2 plasma levels are associated with the severity of coronary artery disease progression in humans.

Methods and Results

In an autocrine-paracrine loop, tumor necrosis factor (TNF)-α promoted the release of LCN2 from murine bone-marrow derived macrophages (BMDM) and vice versa. Moreover, LCN2 stimulation of BMDM led to up-regulation of M1 macrophage markers. In addition, enhanced migration of monocytic J774A.1 cells towards LCN2 was observed. Furthermore, LCN2 increased the expression of the scavenger receptors Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) as well as scavenger receptor class A-1 (SRA-1) and induced the conversion of macrophages to foam cells. In atherosclerotic lesions of low density lipoprotein receptor-deficient (ldlr^−/−) mice fed a high fat, high cholesterol diet, LCN2 was found to be co-localized with macrophages in the shoulder region of the atherosclerotic plaque. In addition, LCN2 plasma levels were significantly increased in plasma samples of these mice. Finally, LCN2 plasma levels correlated with the severity of coronary artery disease (CAD) in patients as determined by coronary angiography.

Conclusions

Here we demonstrated that LCN2 plays a pivotal role in processes involved in atherogenesis by promoting polarization and migration of monocytic cells and development of macrophages towards foam cells. Moreover, LCN2 may be used as a prognostic marker to determine the status of CAD progression.

Acute perioperative-stress-induced increase of atherosclerotic plaque volume and vulnerability to rupture in apolipoprotein-E-deficient mice is amenable to statin treatment and IL-6 inhibition

Myocardial infarction and stroke are frequent after surgical procedures and consume a considerable amount of benefit of surgical therapy. Perioperative stress, induced by surgery, is composed of hemodynamic and inflammatory reactions. The effects of perioperative stress on atherosclerotic plaques are ill-defined. Murine models to investigate the influence of perioperative stress on plaque stability and rupture are not available. We developed a model to investigate the influence of perioperative stress on plaque growth and stability by exposing apolipoprotein-E-deficient mice, fed a high cholesterol diet for 7 weeks, to a double hit consisting of 30 min of laparotomy combined with a substantial blood loss (approximately 20% of total blood volume; 400 µl). The innominate artery was harvested 72 h after the intervention. Control groups were sham and baseline controls. Interleukin-6 (IL-6) and serum amyloid A (SAA) plasma levels were determined. Plaque load, vascular smooth muscle cell (VSMC) and macrophage content were quantified. Plaque stability was assessed using the Stary score and frequency of signs of plaque rupture were assessed. High-dose atorvastatin (80 mg/kg body weight/day) was administered for 6 days starting 3 days prior to the double hit. A single dose of an IL-6-neutralizing antibody or the fusion protein gp130-Fc selectively targeting IL-6 trans-signaling was subcutaneously injected. IL-6 plasma levels increased, peaking at 6 h after the intervention. SAA levels peaked at 24 h (n=4, P<0.01). Plaque volume increased significantly with the double hit compared to sham (n=8, P<0.01). More plaques were scored as complex or bearing signs of rupture after the double hit compared to sham (n=5-8, P<0.05). Relative VSMC and macrophage content remained unchanged. IL-6-inhibition or atorvastatin, but not blocking of IL-6 trans-signaling, significantly decreased plaque volume and complexity (n=8, P<0.01). Using this model, researchers will be able to further investigate the pathophysiology of perioperative plaque stability, which can result in myocardial infarction, and, additionally, to test potential protective strategies.

Summary: We developed a model to study the dynamics of atherosclerotic plaque growth and stability following surgery, and show that IL-6 inhibition and statins beneficially affect plaque volume and complexity.

Toll-like receptor 2/6 agonist macrophage-activating lipopeptide-2 promotes reendothelialization and inhibits neointima formation after vascular injury

OBJECTIVE

Reendothelialization after vascular injury (ie, balloon angioplasty or stent implantation) is clinically extremely relevant to promote vascular healing. We here investigated the therapeutic potential of the toll-like receptor 2/6 agonist macrophage-activating lipopeptide (MALP)-2 on reendothelialization and neointima formation in a murine model of vascular injury.

APPROACH AND RESULTS

The left common carotid artery was electrically injured, and reendothelialization was quantified by Evans blue staining after 3 days. A single injection of MALP-2 (1 or 10 µg, IV) after vascular injury accelerated reendothelialization (P<0.001). Proliferation of endothelial cells at the wound margins determined by 5-ethynyl-2'-deoxyuridine incorporation was significantly higher in MALP-2-treated animals (P<0.05). Furthermore, wire injury-induced neointima formation of the left common carotid artery was completely prevented by a single injection of MALP-2 (10 µg, IV). In vitro, MALP-2 induced proliferation (BrdU incorporation) and closure of an artificial wound of endothelial cells (P<0.05) but not of smooth muscle cells. Protein array and ELISA analysis of isolated primary endothelial cells and ex vivo stimulated carotid segments revealed that MALP-2 stimulated the release of multiple growth factors and cytokines predominantly from endothelial cells. MALP-2 induced a strong activation of the mitogen-activated protein kinase cascade in endothelial cells, which was attenuated in smooth muscle cells. Furthermore, MALP-2 significantly enhanced circulating monocytes and hematopoietic progenitor cells.

CONCLUSIONS

The toll-like receptor 2/6 agonist MALP-2 promotes reendothelialization and inhibits neointima formation after experimental vascular injury via enhanced proliferation and migration of endothelial cells. Thus, MALP-2 represents a novel therapeutic option to accelerate reendothelialization after vascular injury.

Experimental gingivitis induces systemic inflammatory markers in young healthy individuals: a single-subject interventional study

Objectives

We here investigated whether experimental gingivitis enhances systemic markers of inflammation which are also known as surrogate markers of atherosclerotic plaque development.

Background

Gingivitis is a low-level oral infection induced by bacterial deposits with a high prevalence within Western populations. A potential link between the more severe oral disease periodontitis and cardiovascular disease has already been shown.

Methods

37 non-smoking young volunteers with no inflammatory disease or any cardiovascular risk factors participated in this single-subject interventional study with an intra-individual control. Intentionally experimental oral inflammation was induced by the interruption of oral hygiene for 21 days, followed by a 21-days resolving phase after reinitiation of oral hygiene. Primary outcome measures at baseline, day 21 and 42 were concentrations of hsCRP, IL-6, and MCP-1, as well as adhesion capacity and oxLDL uptake of isolated blood monocytes.

Results

The partial cessation of oral hygiene procedures was followed by the significant increase of gingival bleeding (34.0%, P<0.0001). This local inflammation was associated with a systemic increase in hsCRP (0.24 mg/L, P = 0.038), IL-6 (12.52 ng/L, P = 0.0002) and MCP-1 (9.10 ng/l, P = 0.124) in peripheral blood samples between baseline and day 21, which decreased at day 42. Monocytes showed an enhanced adherence to endothelial cells and increased foam cell formation after oxLDL uptake (P<0.050) at day 21 of gingivitis.

Conclusions

Bacterial-induced gingival low-level inflammation induced a systemic increase in inflammatory markers. Dental hygiene almost completely reversed this experimental inflammatory process, suggesting that appropriate dental prophylaxis may also limit systemic markers of inflammation in subjects with natural gingivitis. International Clinical Trials Register Platform of the World Health Organization, registry number: DRKS00003366, URL: http://apps.who.int/trialsearch/Default.aspx

Role of suppressor of cytokine signaling-1 in murine atherosclerosis

Background

While the impact of inflammation as the substantial driving force of atherosclerosis has been investigated in detail throughout the years, the influence of negative regulators of pro-atherogenic pathways on plaque development has remained largely unknown. Suppressor of cytokine signaling (SOCS)-1 potently restricts transduction of various inflammatory signals and, thereby modulates T-cell development, macrophage activation and dendritic cell maturation. Its role in atherogenesis, however has not been elucidated so far.

Methods and Results

Loss of SOCS-1 in the low-density lipoprotein receptor deficient murine model of atherosclerosis resulted in a complex, systemic and ultimately lethal inflammation with increased generation of Ly-6C^hi monocytes and activated macrophages. Even short-term exposure of these mice to high-cholesterol dieting caused enhanced atherosclerotic plaque development with accumulation of M1 macrophages, Ly-6C positive cells and neutrophils.

Conclusion

Our data not only imply that SOCS-1 is athero-protective but also emphasize the fundamental, regulatory importance of SOCS-1 in inflammation-prone organisms.

Transsignaling of interleukin-6 crucially contributes to atherosclerosis in mice

OBJECTIVE

Transsignaling of interleukin (IL)-6 is a central pathway in the pathogenesis of disorders associated with chronic inflammation, such as Crohn disease, rheumatoid arthritis, and inflammatory colon cancer. Notably, IL-6 also represents an independent risk factor for coronary artery disease (CAD) in humans and is crucially involved in vascular inflammatory processes.

METHODS AND RESULTS

In the present study, we showed that treatment with a fusion protein of the natural IL-6 transsignaling inhibitor soluble glycoprotein 130 (sgp130) and IgG1-Fc (sgp130Fc) dramatically reduced atherosclerosis in hypercholesterolemic Ldlr(-/-) mice without affecting weight gain and serum lipid levels. Moreover, sgp130Fc treatment even led to a significant regression of advanced atherosclerosis. Mechanistically, endothelial activation and intimal smooth muscle cell infiltration were decreased in sgp130Fc-treated mice, resulting in a marked reduction of monocyte recruitment and subsequent atherosclerotic plaque progression. Of note, patients with CAD exhibited significantly lower plasma levels of endogenous sgp130, suggesting that a compromised counterbalancing of IL-6 transsignaling may contribute to atherogenesis in humans.

CONCLUSIONS

These data clarify, for the first time, the critical involvement of, in particular, the transsignaling of IL-6 in CAD and warrant further investigation of sgp130Fc as a novel therapeutic for the treatment of CAD and related diseases.

Chemokine receptor 7 knockout attenuates atherosclerotic plaque development

BACKGROUND

Atherosclerosis is a systemic inflammatory disease characterized by the formation of atherosclerotic plaques. Both innate immunity and adaptive immunity contribute to atherogenesis, but the mode of interaction is poorly understood. Chemokine receptor 7 (CCR7) is critically involved in the transition from innate to adaptive immune activation by coordinating the migration to and positioning of antigen-presenting dendritic cells and T cells in secondary lymphoid organs. More recently, it was shown that CCR7 is also responsible for T-cell migration into inflamed tissues and T-cell egress from these tissues via the afferent lymph. Thus, we investigated the influence of a systemic CCR7 deficiency on atherogenesis in atherosclerosis-prone low-density lipoprotein receptor (ldlr) knockout mice.

METHODS AND RESULTS

CCR7 deficiency resulted in reduced atherosclerotic plaque development. CCR7(-/-) T cells showed impaired entry and exit behavior from atherosclerotic lesions. Oxidized low-density lipoprotein, a key molecule for atherogenesis with antigenic features, was used to pulse dendritic cells and to expand T cells ex vivo. Adoptive transfer of C57BL/6 wild-type T cells but not ccr7(-/-)-derived T cells primed with oxidized low-density lipoprotein-pulsed dendritic cells resulted in a reconstitution of atherogenesis in ccr7(-/-)/ldlr(-/-) mice.

CONCLUSION

These results demonstrate that both CCR7-dependent T-cell priming in secondary lymphoid organs and CCR7-dependent recirculation of T cells between secondary lymphoid organs and inflamed tissue are crucially involved in atherosclerotic plaque development.

How much is too much? Interleukin-6 and its signalling in atherosclerosis

The importance of inflammation as a driver of pathology is no longer confined to autoimmune and infectious diseases. In line with convincing experimental data as well as abundant clinical findings the current view of atherosclerosis points to inflammation as a critical regulator of atherosclerotic plaque formation and progression leading to the fatal clinical endpoints myocardial infarction, stroke or sudden cardiac death. The underlying mechanisms have been a matter of intense research during the last decades. In this regard, the interleukin-6 (IL-6) cytokines and their signalling events have been shown to contribute to both, atherosclerotic plaque development and plaque destabilisation via a variety of mechanisms. These involve the release of other pro-inflammatory cytokines, oxidation of lipoproteins by phospholipases, stimulation of acute phase protein secretion, the release of prothrombotic mediators, and the activation of matrix metalloproteinases. Moreover, the formation of reactive oxygen species generated by vascular enzyme systems may play a critical role in the regulation of IL-6 indicating a cross talk between vasoactive substances i.e. angiotensin II or adrenalin and pro-inflammatory cytokines such as IL-6. In this review we will summarise and discuss the underlying molecular and cellular mechanisms how IL-6 as an early and central regulator of inflammation contributes to atherosclerosis and how this knowledge can be integrated into the clinical context.

Nitric oxide reduces organ injury and enhances regeneration of reduced-size livers by increasing hepatic arterial flow

Background

Reduced-size livers suffer from portal hyperperfusion, diminished arterial blood flow and the risk of postoperative liver injury. The aim of this experimental study was to unravel the role of nitric oxide in this setting.

Methods

Rats underwent 85 per cent partial hepatectomy and either substitution of nitric oxide with molsidomine or inhibition of nitric oxide synthase (NOS) with NG-nitro-l-arginine methyl ester. Untreated hepatectomized animals served as controls and unresected animals as the sham group.

Results

Ultrasonic flowmetry following partial hepatectomy revealed a marked increase in portal venous inflow with a concomitant decrease in hepatic arterial inflow. Nitric oxide substitution counteracted the decline in hepatic arterial inflow and caused a significantly greater increase in cell proliferation after partial hepatectomy compared with control or NOS-inhibited animals. Hepatectomized animals further profited from nitric oxide substitution, as indicated by reduced aminotransferase release and improved liver function.

Conclusion

Nitric oxide improves the postoperative course of rats with reduced-size livers by modulating hepatic macrohaemodynamics and mediating regeneration and cytoprotection, but not by reducing hepatic hyperperfusion and the accompanying sinusoidal shear stress.

NO counterbalances HO-1 overexpression-induced acceleration of hepatocyte proliferation in mice

The trigger for liver regeneration, including shear stress, has been the subject of ongoing debate. Blood vessel-derived gaseous molecules carbon monoxide (CO) and nitric oxide (NO) regulate vascular tone and play an important role in liver regeneration. In heme oxygenase-1 (HO-1) transgenic mice, it has been shown that CO-mediated impairment of vasorelaxation is an NO-dependent event. We therefore studied liver regeneration in HO-1 overexpressing animals in dependency of NO availability. Mice were subjected to (2/3) hepatectomy and were treated with either cobalt protoporphyrin-IX for induction of CO-liberating HO-1, N(omega)-nitro-L-arginine methyl ester (L-NAME) for blockade of NO synthase (NOS) or both. Application of molsidomine in L-NAME treated animals served for resubstitution of NO. Vehicle-treated animals served as respective control animals. We examined 5-bromo-2'-deoxyuridine incorporation and proliferating cell nuclear antigen expression as well as HO-1 and NOS-2 protein levels. Intrahepatic red blood cell velocity and volumetric blood flow were evaluated by in vivo fluorescence microscopy as indicators for microvascular shear stress. Hepatic regeneration remained unaffected by L-NAME application for NOS blockade. However, NOS blockade in HO-1 induced animals caused increased 5-bromo-2'-deoxyuridine and proliferating cell nuclear antigen measures of liver regeneration. In parallel, these animals revealed increased velocities and volumetric blood flow in the terminal afferent vessels and postsinusoidal venules. These local hemodynamic changes including enhanced hepatocyte proliferation could be reversed by NO liberation via molsidomine. The present findings stress the role of NO to counterbalance vascular tone in HO-1 overexpressing animals for maintenance of adequate perfusion and salutary shear force within the hepatic microvasculature upon liver resection.

Inhibition of Heme Oxygenase-1 Protects Against Tissue Injury in Carbon Tetrachloride Exposed Livers

BACKGROUND/AIMS

During the metabolism of the hepatotoxin carbon tetrachloride (CCl(4)) by cytochrome P450, heme, and free radicals are released. Heme oxygenase (HO-1) is an enzyme that is induced by heme as well as oxidative stress and has been reported to be involved in mediating protection against toxic liver injury. The purpose of the present study was to specify the role of HO-1 in CCl(4)-hepatotoxicity.

METHODS AND RESULTS

We could demonstrate an up-regulation of HO-1 protein in CCl(4)-exposed liver tissue that reaches its maximum after 6 to 12 h, along with intrahepatic leukocyte accumulation and tissue injury. When animals were pretreated with hemin for augmentation of HO-1 expression, CCl(4)-exposure was associated with a reduction of intrahepatic leukocyte accumulation, while inhibition of CCl(4)-induced HO-1 expression by tin protoporphyrin-IX (SnPP-IX) enhanced leukocytic response. Of interest, however, liver morphology, transaminases, and bile flow as parameters of hepatocellular integrity and excretory function did not concur with reduced leukocyte numbers in the hepatic microcirculation, and revealed best organ function and tissue preservation in case of HO-1 inhibition by SnPP-IX. In contrast, hemin-treated CCl(4)-exposed livers demonstrated pathologic enzyme release and cholestasis.

CONCLUSIONS

Taken together, inhibition of HO-1 in CCl(4)-hepatotoxicity protected the liver, while higher HO-1 activity harmed liver tissue, most probably due to interference of the HO-1 pathway with CCl(4)-dependent metabolism via cytochrome P450 and heme overload-associated toxicity.

Pifithrin-alpha induced p53 inhibition does not affect liver regeneration after partial hepatectomy in mice

BACKGROUND/AIMS

Beside its well-known function as tumour suppressor gene, p53 is supposed to positively regulate cell division and cell differentiation. Because hepatocyte proliferation has been reported to be reduced by blockade of p53 function in vitro, we examined in the present study the impact of p53 inhibition on hepatocyte proliferation in vivo.

METHODS

Mice treated with either pifithrin-alpha (PFT), a p53-inactivating agent, or the equivalent volume of vehicle, were subjected to 70% hepatectomy. In addition to assessment of liver mass restitution we examined p53 and p21 protein expression as well as PCNA expression and BrdU incorporation by using Western blot and immunohistochemical techniques. Extent of apoptosis was assessed by TUNEL assay.

RESULTS

PFT lowered nuclear but not cytoplasmic p53, and did not inhibit protein expression of regeneration-associated p21. PCNA protein expression as well as PCNA and BrdU immunohistochemistry did not differ between regenerating livers of either PFT- or vehicle-treated animals. Moreover, TUNEL analysis of regenerated liver tissue revealed comparable numbers of apoptotic cells in both groups.

CONCLUSIONS

Pharmacological inhibition of p53 did not impair liver regeneration in mice, implying that p53 is functionally redundant in that p53-independent pathways compensate for the blockade of p53 and sufficiently support the process of hepatocyte replication in liver regeneration.

Differential effects of atropine and isoproterenol on inducibility of atrioventricular nodal reentrant tachycardia

BACKGROUND

Radiofrequency ablation of the "slow pathway" in atrioventricular nodal reentrant tachycardia (AVNRT) relies on tachycardia non-inducibility after ablation as success criterion. However, AVNRT is frequently non-inducible at baseline. Thus, autonomic enhancement using either atropine or isoproterenol is frequently used for arrhythmia induction before ablation.

METHODS

80 patients (57 women, 23 men, age 50+/-14 years) undergoing slow pathway ablation for recurrent AVNRT were randomized to receive either 0.01 mg/kg atropine or 0.5-1.0 microg/kg/min isoproterenol before ablation after baseline assessment of AV conduction. The effects of either drug on ante- and retrograde conduction was assessed by measuring sinus cycle length, PR and AH interval, antegrade and retrograde Wenckebach cycle length (WBCL), antegrade effective refractory period (ERP) of slow and fast pathway and maximal stimulus-to-H interval during slow and fast pathway conduction.

RESULTS

Inducibility of AVNRT at baseline was not different between patients randomized to atropine (73%) and isoproterenol (58%) but was reduced after atropine (45%) compared to isoproterenol (93%, P<0.001). Of the 28 patients non-inducible at baseline isoproterenol rendered AVNRT inducible in 21, atropine in 4 patients. Dual AV nodal pathway physiology was present in 88% before and 50% after atropine compared to 83% before and 73% after isoproterenol. Whereas both drugs exerted similar effects on ante- and retrograde fast pathway conduction maximal SH interval during slow pathway conduction was significantly shorter after isoproterenol (300+/-48 ms vs. 374+/-113 ms, P=0.012).

CONCLUSION

Isoproterenol yields higher AVNRT inducibility than atropine in patients non-inducible at baseline. This may be caused by a more pronounced effect on antegrade slow pathway conduction.