Characterization of the mitochondrial unfolded protein response in human coronary artery endothelial cells

Background

The unfolded protein response of the endoplasmic reticulum (UPRER) is highly activated in cardiovascular diseases and aims to restore homeostasis by improving protein folding. An analogue cytoprotective mitochondrial unfolded protein response (UPRMito) regulated by an orthologue of the activating transcription factor 5 (ATF5) was described in model organism c. elegans. However, in humans it is not clear if there is a distinct UPRMito, and if there is an activation of an UPRMito during stress induced by cardiovascular diseases. The endothelium is subjected to high levels of mitochondrial stress, e.g. in atherosclerosis.

Purpose

To provide a systematic characterization of the UPRMito in human coronary artery endothelial cells (HCAEC).

Methods and results

HCAEC were treated with Nicotinamide Riboside (NR), a NAD+ precursor that activates UPRMito without inducing cellular stress. NR treatment did not induce toxicity and improved cell viability at a concentration of 100μM NR. Quantitative PCR confirmed a dose-dependent upregulation of UPRMito markers. Additionally, we measured expression of ATF4, which is discussed to regulate an integrated stress response in mammals by activating both the UPRMito and UPRER. ATF4 upregulation upon NR treatment was more pronounced than ATF5 upregulation. Analysis of GTEX-Data showed that ATF5 is almost exclusively expressed in liver tissue, while ATF4 shows ubiquitous expression. Among 54 tissues, aortic tissue and coronary arterial tissue are among the five tissues with the highest ATF4 expression.

Analysis of RNA-seq-data of human carotid atherosclerosis revealed that the two transcription factors are differentially regulated. ATF4 is downregulated in unstable plaque, while ATF5 is upregulated. Moreover, ATF4 is in both conditions highly more abundant than ATF5. Accordingly, endothelial cells incubated under atherosclerotic conditions (oxLDL + high glucose) exhibited a ATF4 down- and ATF5 upregulation. Genes previously described to be involved in the UPRMito exhibited a similar expression pattern as ATF4.

To further elucidate these findings, we will perform transcriptomic analyses of HCAEC treated with atherosclerotic stimuli (IL-1β, oxLDL), UPRER inductors (Thapsigargin, Tunicamycin) and stressors of mitochondrial proteostasis (Oligomycin, MitoBloCK-6), to analyze, if ATF5- or ATF4-related pathways are dysregulated. Specific inhibitors and UPRMito activators will be used to investigate the significance of ATF4 and ATF5 on endothelial cell function (proliferation, migration, apoptosis, monocyte adhesion).

Conclusion

The UPRMito is dysregulated during the pathogenesis of atherosclerosis in HCAEC. Further findings are required to elucidate, if the UPRMito is activated separately and specifically by ATF5 or as part of an integrated cellular stress response by ATF4. A deeper understanding of these stress responses is crucial for the identification of novel therapeutic targets in atherosclerosis.

Funding Acknowledgement

Type of funding sources: Public hospital(s). Main funding source(s): University hospital Bonn

Serum levels of the endoplasmic-reticulum-stress chaperone GRP78 identify patients with coronary artery disease and predict mortality

Background

Endoplasmic-reticulum-stress (ER Stress) and associated chaperones like the main ER-Stress moderator GRP78 (glucose-regulated-protein, 78kDa) are involved in the pathogenesis of coronary artery disease (CAD). In addition to their intracellular localization and effects, secretion and extracellular properties of chaperones, including GRP78, were recently described. However, a diagnostic or prognostic relevance of serum ER-chaperones in patients with CAD has not been established yet.

Purpose

To investigate the significance of serum GRP78 in patients undergoing coronary angiography for suspected CAD.

Methods

Serum concentration of GRP78 was measured by ELISA in 789 patients with indication for coronary angiography (both ACS and CCS). CAD was defined as >50% stenosis in any major coronary artery. Clinical endpoint was one-year all-cause mortality.

Results

Mean age was 70.8±11.9 years and 65% of patients were male. 192 (24%) patients presented with acute coronary syndrome (ACS). CAD was found in 72.4% of patients. Mean GRP78 serum concentration was 2492 ng/ml. Increased levels of GRP78 (> median) were associated with diabetes (29.9% vs. 23.1%, p=0.03), a higher BMI (28.9±7.1 kg/m2 vs. 27.0±6.0 kg/m2, p<0.0001) and chronic kidney disease (CKD: 23.3% vs. 17.1%, p=0.03). There was no difference regarding age or sex.

GRP78 levels were increased in patients with CAD when compared to patients without CAD (2640 ng/ml [95% CI: 2415–2864] vs. 2178 ng/ml [95% CI: 1893–2463], p=0.013, Fig A). Interestingly, GRP78 levels were lower in patients with ACS than in patients with CCS (2284 ng/ml [95% CI: 1944–2642] vs. 2822 [95% CI: 2531–3113], p=0.018, Fig B). To further elucidate these findings, we analyzed available proteomics of patients with hypertrophic cardiomyopathy undergoing septal ablation as a model for a planned myocardial infarction (PMI)1. Coronary sinus blood samples drawn 10 and 60 min after PMI showed a downregulation of GRP78 levels compared to baseline.

Finally, we assessed prognostic relevance of GRP78 in patients with CAD. Increased GRP78 levels were associated with lower one-year mortality (5.3% vs. 10.6% vs. p=0.016). Increased GRP78 levels were associated with reduced one-year mortality in both continuous (HR: 0.48 [95% CI: 0.25–0.92]) and categorial analyses stratified by median GRP78. After adjusting for age, sex, BMI, diabetes, CKD and ACS, GRP78 remained an independent predictor of one-year mortality (HR: 0.51 [0.26–0.96], p=0.039).

Conclusion

GRP78 serum levels are generally elevated in patients with CAD but downregulated during ACS. Reduced levels are associated with increased one-year mortality. These results support previous findings that GRP78 secretion is a protective mechanism in cardiovascular diseases. Further mechanistic studies are warranted to foster our understanding of the effects of extracellular GRP78 and to aid in the identification of modifying therapeutic targets.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): University hospital Bonn

Machine learning identifies clinical parameters to predict mortality in patients undergoing transcatheter mitral valve repair

Background

Transcatheter Mitral Valve Repair (TMVR) with MitraClip is an important treatment option for patients with severe mitral regurgitation. The lack of appropriate, validated and specific means to risk stratify TMVR patients complicates the evaluation of prognostic benefits of TMVR in clinical trials and practice.

Purpose

We aimed to develop an optimized risk stratification model for TMVR patients using machine learning (ML).

Methods

We included a total of 1009 TMVR patients from three large university hospitals, of which one (n=317) served as an external validation cohort. The primary endpoint was all-cause 1-year mortality, which was known in 95% of patients. Model performance was assessed using receiver operating characteristics. In the derivation cohort, different ML algorithms, including random forest, logistic regression, support vectors machines, k nearest neighbors, multilayer perceptron, and extreme gradient boosting (XGBoost) were tested using 5-fold cross-validation in the derivation cohort. The final model (Transcatheter MITral Valve Repair MortALIty PredicTion SYstem; MITRALITY) was tested in the validation cohort with respect to existing clinical scores.

Results

XGBoost was selected as the final algorithm for the MITRALITY Score, using only six baseline clinical features for prediction (in order of predictive importance): blood urea nitrogen, hemoglobin, N-terminal prohormone of brain natriuretic peptide (NT-proBNP), mean arterial pressure, body mass index, and creatinine. In the external validation cohort, the MITRALITY Score's area under the curve (AUC) was 0.783, outperforming existing scores which yielded AUCs of 0.721 and 0.657 at best. 1-year mortality in the MITRALITY Score quartiles across the total cohort was 0.8%, 1.3%, 10.5%, and 54.6%, respectively. Odds of mortality in MITRALITY Score quartile 4 as compared to quartile 1 were 143.02 [34.75; 588.57]. Survival analyses showed that the differences in outcomes between the MITRALITY Score quartiles remained even over a timeframe of 3 years post intervention (log rank: p<0.005). With each increase by 1% in the MITRALITY score, the respective proportional hazard ratio for 3-year survival was 1.06 [1.05, 1.07] (Cox regression, p<0.05).

Conclusion

The MITRALITY Score is a novel, internally and externally validated ML-based tool for risk stratification of patients prior to TMVR. These findings may potentially allow for more precise design of future clinical trials, may enable novel treatment strategies tailored to populations of specific risk and thereby serve future daily clinical practice.

Funding Acknowledgement

Type of funding sources: None. Summary Figure

Circulating microRNA-122-5p correlates with improvement in left-ventricular function after transcatheter aortic valve replacement and regulates viability of cardiomyocytes via extracellular vesicles

 

Transcatheter aortic valve replacement (TAVR) is a well-established treatment option for high- and intermediate-risk patients with severe symptomatic aortic valve stenosis (AVS). However, a specific role for circulating microRNAs (miRNAs) in the improvement of cardiac function for patients after TAVR has not yet been investigated. Herein, we generally explored the differential expression of miRNAs in circulating extracellular vesicles (EV-miRNAs) in patients after TAVR and, in particular, the novel role of circulating miR-122-5p in cardiomyocytes.

Circulating EV-associated miRNAs were investigated by using an unbiased Taqman-based human miR array. Several EV-miRNAs (miR-122-5p, miR-26a, miR-192, miR-483-5p, miR-720, miR-885-5p, and miR-1274) were significantly deregulated in aortic stenosis patients at day seven after TAVR in comparison to the pre-procedural levels in patients without LVEF-improvement. The higher levels of miR-122 were negatively correlated with LVEF improvement at both day seven (r=−0.264 and p=0.015) and at six months (r=−0.328 and p=0.0018) after TAVR. At the three-year follow-up, patients with a higher level of miR-122-5p displayed significantly increased cardiovascular mortality (p=0.03). By utilization of patient-derived samples and a murine aortic-stenosis model, we observed that the expression of miR-122-5p correlates negatively with cardiac function, which is associated with LVEF. Graded wire-injury-induced aortic-valve-stenotic mice demonstrated a higher level of miR-122-5p, which was related to cardiomyocyte dysfunction. Murine ex vivo experiments revealed that miR-122-5p is highly enriched in endothelial cells in comparison to cardiomyocytes. Co-culture experiments with endothelial cells and cardiomyocytes, copy-number analysis, fluorescence microscopy with Cy3-labeled miR-122-5p demonstrated that miR-122-5p can be shuttled via large extracellular vesicles from endothelial cells into cardiomyocytes. Gain- and loss-of-function experiments suggested that EV-mediated shuttling of miR-122-5p increases the level of miR-122-5p in recipient cardiomyocytes and regulates viability of the cardiomyocytes. In silico prediction and mass spectrometry were used to search for binding partners of miR-122-5p. Mechanistically, miR pulldown, electrophoretic mobility shift assay, and RNA immunoprecipitation confirmed that miR-122-5p interacts with an RNA-binding protein, hnRNPU, in a sequence-specific manner to encapsulate miR-122-5p into large EVs. Upon shuttling into recipient cells, miR-122-5p negatively regulates the expression of the anti-apoptotic gene BCL2, by binding to its 3' untranslated region to regulate its translation, and thereby decreasing the viability of target cardiomyocytes.

Increased levels of circulating pro-apoptotic EV-incorporated miR-122-5p is associated with reduced LVEF after TAVR. Extracellular vesicular shuttling of miR-122-5p regulates the viability and apoptosis of cardiomyocytes in a Bcl2-dependent manner.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): German Research Foundation (DFG); German Society of Cardiology (DGK)

Vitamin K epoxide reductase complex subunit 1-like 1 (VKORC1L1) inhibition induces a proliferative and pro-inflammatory vascular smooth muscle cell phenotype

Background

Vitamin K antagonists (VKA) like Warfarin are known to promote adverse cardiovascular remodelling. Contrarily, vitamin K supplementation has been discussed to decelerate cardiovascular disease. The recently described VKOR-isoenzyme Vitamin K epoxide reductase complex subunit 1-like 1 (VKORC1L1) is involved in vitamin K maintenance and exerts antioxidant properties. In this study, we sought to investigate the role of VKORC1L1 in neointima formation and on vascular smooth muscle cell (VSMC) function.

Methods and results

Treatment of wild-type mice with Warfarin increased maladaptive neointima formation after carotid artery injury. This was accompanied by reduced vascular mRNA expression of VKORC1L1.

In vitro, Warfarin was found to reduce VKORC1L1 mRNA expression in VSMC. VKORC1L1 downregulation by siRNA promoted viability, migration and formation of reactive oxygen species. VKORC1L1 knockdown further increased expression of key markers of vascular inflammation (NFκB, IL-6). Additionally, downregulation of the endoplasmic reticulum (ER) membrane resident VKORC1L1 increased expression of the main ER Stress moderator, glucose-regulated protein 78 kDa (GRP78). Moreover, treatment with the ER Stress inducer Tunicamycin promoted VKORC1L1, but not VKORC1 expression.

Finally, we sought to investigate, if treatment with vitamin K can mediate the protective properties of VKORC1L1. Thus, we examined effects of menaquinone-7 (MK7) on VSMC phenotype switch. MK7 treatment dose-dependently alleviated PDGF-induced proliferation and migration. In addition, we detected a reduction in expression of inflammatory and ER Stress markers.

Conclusion

VKA-induced neointima formation is associated with reduced vascular VKORC1L1 expression. VKORC1L1 inhibition contributes to an adverse VSMC phenotype while MK7 restores VSMC function. Thus, MK7 supplementation might be a feasible therapeutic option to modulate vitamin K- and VKORC1L1-mediated vasculoprotection.

Funding Acknowledgement

Type of funding sources: None.

Association of the get with the guidelines heart failure risk score with mortality in patients undergoing transcatheter edge-to-edge mitral valve repair

Background

Reliable risk scores in patients undergoing transcatheter edge-to-edge mitral valve repair (TMVR) are lacking. Heart failure is common in these patients, and risk scores derived from heart failure populations might help stratify TMVR patients.

Methods

Consecutive patients from three Heart Centers undergoing TMVR were enrolled to investigate the association of the “Get with the Guidelines Heart Failure Risk Score” (comprising the variables systolic blood pressure, urea nitrogen, blood sodium, age, heart rate, race, history of COPD) with all-cause mortality.

Results

Among 815 patients with available data 177 patients died during a mean follow-up time of 419 days. Estimated one-year mortality by quartiles of the score (0–37; 38–42, 43–47 and more than 47 points) was 6%, 10%, 23% and 30%, respectively (p<0.001). Every increase of one score point was associated with a 9% increase in the hazard of mortality (95% CI 1.06–1.11%, p<0.001). The score was associated with long-term mortality independently of left ventricular ejection fraction, renal function and LogEuroscore, and was equally predictive in primary and secondary mitral regurgitation.

Conclusion

The “Get with the Guidelines Heart Failure Risk Score” showed a strong association with mortality in patients undergoing TMVR with additive information beyond traditional risk factors. Given the routinely available variables included in this score, application is easy and broadly possible.

Funding Acknowledgement

Type of funding source: None

Prognostic impact and post-procedural development of severe tricuspid regurgitation in patients undergoing transcatheter edge-to-edge mitral valve repair

Purpose

The aim of this study was to investigate the clinical impact and post-procedural development of tricuspid regurgitation (TR) in patients undergoing the MitraClip procedure for severe mitral regurgitation.

Methods

In this present multicentre study, we included 940 patients undergoing MitraClip implantation for symptomatic mitral regurgitation from August 2010 to September 2018. Patients were categorized according to concomitant TR (none or mild vs moderate vs severe) and the prognostic impact of TR on 1-year mortality was evaluated. Moreover, in 377 patients, we assessed 3-months echocardiographic controls to further analyse the post-procedural development of TR.

Results

At baseline, concomitant TR was graded none/mild in 393 (42%), moderate in 316 (34%), and severe in 231 (25%) patients. During 1-year follow-up, 141 of 940 (15%) patients died. According to mild/none, moderate and severe TR, mortality rates were 13%, 12%, and 23%, respectively, revealing a higher prevalence of death in patients with severe TR (p=0.001). Kaplan-Meier analysis and log-rank test confirmed inferior survival rates for patients with severe TR (p=0.001), while there were no significant difference in survival rates between patients with none/mild vs moderate TR (p=0.561). Regarding 1-year mortality, multivariate cox regression analysis, revealed an odds ratio of 1.739 (1.024–2.953; p=0.041), associated with severe TR. After 3-months follow-up, echocardiography in 377 patients showed following TR grade distributions: 44% none/mild, 37% moderate and 19% severe TR. In 100 patients (27%), TR improved by one or more grades, while 64 patients (17%) showed a TR worsening. In patients with severe TR at baseline, 42 of 91 (46%) patients showed a reduction in TR of one or more grades. Patients with severe TR at baseline, who showed a TR improvement during 3-months follow-up, had lower rates of 1-year mortality (p=0.025). For these patients, in regression analysis, right atrial area was revealed as only predictor of TR improvement after MitraClip procedure [odds ratio 0.958 (0.918–0.999); p=0.046].

Conclusion

One-fourth of patients undergoing MitraClip procedure for mitral regurgitation had concomitant severe tricuspid regurgitation which was predictive for worse prognosis. Post-procedural TR improvement of one or more grades was frequent in these patients and was associated with higher survival-rates.

Funding Acknowledgement

Type of funding source: None

MIDA mortality risk score in patients undergoing percutaneous edge-to-edge mitral repair

Background

Recent studies indicate that careful patient selection is key for the percutaneous edge-to-edge repair via MitraClip procedure. The MIDA Score represents a useful tool for patient selection and is validated in patients with degenerative mitral regurgitation (MR).

Aim

We here assessed the potential benefit of the MIDA Score for patients with functional or degenerative MR undergoing edge-to-edge mitral valve repair via the MitraClip procedure.

Methods

In the present study, we retrospectively included 520 patients from three Heart Centers undergoing MitraClip implantation for MR. All parameters of the MIDA Score were available in these patients, consisting of the 7 variables age, symptoms, atrial fibrillation, left atrial diameter, right ventricular systolic pressure, left-ventricular end-systolic diameter, left ventricular ejection fraction. According to the median MIDA-Score of 9 points, patients were stratified in to a high and a low MIDA Score group and association with all-cause mortality was evaluated. Moreover, MR was assessed in echocardiographic controls in 370 patients at discharge, 279 patients at 3-months and 222 patients at 12 months after MitraClip implantation.

Results

During 2-years follow-up after MitraClip implantation, 69 of 291 (24%) patients with a high MIDA Score and 25 of 229 (11%) patients with a low MIDA Score died. Kaplan-Meier analysis and log rank test showed inferior rates of death in patients with a low score (p<0.001) and multivariate cox regression revealed an odds ratio of 0.54 (0.31–0.95; p=0.032) regarding 2-year survival in this group. Moreover, one point increase in the MIDA Score was associated with a 1.18-fold increase in the risk for mortality (1.02–1.36; p=0.025). Comparing patients with a high MIDA Score and patients with a low score, post-procedural residual moderate/severe MR tended to be more frequent in patients with a high MIDA Score at discharge (53% vs 43%; p=0.061), 3-months (50% vs 40%; p=0.091) and significantly at 12-months follow-up (52% vs 37%; p=0.029).

Conclusion

The MIDA Mortality Risk Score remained its predictive ability in patients with degenerative or function MR undergoing transcatheter edge-to-edge mitral valve repair. Moreover, a high MIDA score was associated with a higher frequency of post-procedural residual moderate/severe MR, indicating a lower effectiveness of this procedure in these patients.

Funding Acknowledgement

Type of funding source: None

Mechanisms of endothelial cell activation by endocannabinoid 2-arachidonoylglycerol

Background

Endothelial dysfunction promotes atherogenesis, vascular inflammation, and thrombus formation. Reendothelialization after angioplasty is required in order to restore vascular function and to prevent stent thrombosis. The endocannabinoid (eCB) 2-arachidonoylglycerol (2-AG) is a known modulator of inflammation. Earlier studies have demonstrated the relevance of this endocannabinoid in human pathophysiology during coronary artery disease and in murine experimental atherogenesis. However, evidence on the impact of 2-AG on endothelial cell function remains scarce.

Methods

Endothelial repair was studied in two treatment groups of wildtype mice following electrical denudation of the common carotid artery. One group received the monoacylglycerol lipase (MAGL)-inhibitor JZL184, which impairs 2-AG degradation and thus causes elevated 2-AG levels, the other group received DMSO. The residual endothelial gap at five days was visualized by Evan's blue staining in either group. In vitro, the effect of 2-AG on human coronary artery endothelial cell (HCAEC) viability was assessed by an XTT-based assay. Endothelial activation was studied by an adhesion assay of THP-1 monocytes to 2-AG-preconditioned HCAEC. Activation of HCAEC adhesion molecules was characterized by flow cytometry.

Results

Elevated 2-AG levels significantly impaired reendothelialization in wildtype mice following electrical injury of the common carotid artery, resulting in a residual denudation at 5 days of 2291±286 μm vs. 1505±223 μm (n=18–19; p<0.05). In vitro, 2-AG significantly reduced viability of HCAEC at 24 hours (0.31±0.10 vs. 1.00±0.08; n=3; p<0.01). Finally, 2-AG promoted HCAEC activation resulting in a significant increase in THP-1 monocyte adhesion to HCAEC following pre-treatment of HCAEC with 2-AG (0.17±0.03 THP-1 cells per HCAEC vs. 0.07±0.01 THP-1 cells per HCAEC; n=3; p<0.05). Adhesion molecules E-selectin, ICAM-1 and VCAM-1, that are known to be regulated by 2-AG in the venous endothelium, remained unchanged in arterial endothelial cells. Besides, HCAEC migration, ROS-production, expression of NADPH oxidases and secretion of inflammatory cytokines were unaffected by 2-AG.

Conclusion

Elevated 2-AG levels hamper endothelial repair and impair HCAEC proliferation while facilitating adhesion of monocytes. Intriguingly, the underlying mechanisms in the arterial vascular bed appear distinct from venous endothelium. Given that 2-AG is elevated during coronary artery disease in humans, 2-AG might impair reendothelialization after angioplasty and thus impact on clinical outcomes.

Funding Acknowledgement

Type of funding source: None

P985 The use of strain analysis in patients under cardiotoxic chemotherapy: possible early detection of cardiotoxicity

Cardiotoxicity is a frequent side effect of chemotherapy leading to impaired outcomes in cancer survivors. Because of that cardiooncology has recently gained more importance in clinical practice. We aim to echocardiographically evaluate the development of cardiotoxicity and to detect early signs for preventing severe cardiomyopathies by repeated strain analysis.

We included 80 patients (46.7 ± 14.7 years, 75% female) under diverse cardiotoxic chemotherapies (43.7% breast cancer, 43.7% haematological malignancy, 12.5% others). All patients underwent echocardiography before and during treatment. Follow-up echocardiography was performed approximately 5.5 ± 1.2 months after the first application of the chemotherapy. The apical four-chamber view was used to perform strain analysis employing dedicated and automated offline software as shown previously.

Eight patients deceased due to oncological complications during follow up. Twelve patients showed significant reduced left ventricle ejection fraction (LVEFbaseline 63.2 ± 4.5%, LVEFFollow-up 48.6 ± 7.8%, p = 0.02) correlated with decrease in left ventricular global longitudinal strain (LV-GLSbaseline 17.1 ± 5.2%, LV-GLSFollow-up 9.7 ± 3.2%, p = 001). All of these patients presented heart failure symptoms, mostly with dyspnoea (85% functional NYHA class > II) and oedema (65%). In 15 patients we found a reduction of left ventricular global longitudinal strain from <5% without relevant reduction of LVEF. However, these patients showed also heart failure symptoms. During follow up 20 patients had to be admitted due to decompensated heart failure. Four patients deceased due to cardiovascular causes.

Delta LV-GLS (LV-GLSbaseline – LV-GLSFollow-up) was found to be strongest independent predictor of mortality. Baseline LV-GLS < 15% was found to be associated with mortality and frequent rehospitalisation.

Solely LVEF is insufficient to detect cardiotoxicity and to estimate prognosis of patients under cardiotoxic chemotherapy. In our small patient collective we found baseline LV-GLS <15% to be an adequate parameter for prognosis estimation and delta LV-GLS > 5% a strongest independent predictor for mortality in patients with preserved LVEF under cardiotoxic chemotherapy.

P908 The novel predictor for mortality in patients with functional mitral regurgitation: the modified MIDA-Score

EuroSCORE and STS-Score are used to assess surgical risk in patients with valvular heart diseases. The MIDA- Score has been recently published as a representative predictor for short- and long-term prognosis in patients with degenerative mitral regurgitation (DMR). The adequate assessment of long-term prognosis in patients with functional MR is scarce. We aim to adapt this classical score system for patients with FMR.

We retrospectively included 105 patients with FMR who underwent transcatheter mitral regurgitation therapy (TMVR) between January 2014 and August 2016 in our center. Due to the different underlying pathomechanisms of FMR, annular dilatation and impaired left ventricle function, and more elderly patient population we adapted some cut-off values to FMR patients (Age > 65 to Age > 75; LV-EF ≤ 60% to LV-EF ≤ 45%; sPAP≥50mmHg to sPAP≥45mmHg). Moreover, according to Cox proportional hazard analysis of our patient collective we re-calculated the weights of the risk factors: Age 2 points, Symptoms 1 point, atrial fibrillation 2 points, left atrial diameter 1 point, right ventricle systolic pressure 2 points, left ventricle end-systolic diameter 2 points, left ventricle ejection fraction 2 points. We defined three risk groups according to total points from the risk factors; Grade 1 (0-4 points): low risk, Grade 2 (5-9 points): moderate risk, Grade 3 (10-12 points): high risk.

We retrospectively included 105 patients (76.7 ± 8.8 years, 50,6% female) with symptomatic (functional NYHA class > II ) moderate-to-severe FMR (PISA: 0.7 ± 0.4cm, VC width: 0.8 ± 0.3cm, EROA: 0.22cm2, RegVol: 38.1 ± 19.2ml) at surgical high risk (EuroSCORE II: 5.4 ± 3.8%, STS-Score: 4.7 ± 2.8%). We found all-cause mortality 7% at one-year follow-up. 34.1% of our collective were hospitalized.

The classical MIDA Score was not significantly correlated with mortality and rehospitalization in patients with FMR at follow-up (p = 0.5); however, the modified MIDA score was found to be a strong predictor for mortality and rehospitalization in patients with FMR (AUC: 0.89). According to multivariate analysis, the modified MIDA score was found to be superior compared to the other conventional score systems (The modified MIDA-Score HR: 4.1, p = 0.021; EuroSCORE II; HR: 1.2, p = 0.004, STS-Score; HR: 1.7, p = 0.005).

We performed Cox proportional hazard analysis to assess the weighting factor of the predictors. As a result of this, we found age (HR: 2,95, p = 0.03) as the most reliable parameter to predict the combined outcome.

The 12,5% of grade 1, 27% grade 2, 57% grade 3 patients showed combined endpoint. According to regression analysis, the modified score >9 points found to be a strong predictor for high mortality and rehospitalization (OR: 3.35, p = 0.011).

We found the modified MIDA Score sufficient and extensive to assess outcomes in patients with FMR. The modified MIDA Score offers a sufficient promising tool to predict individual prognosis in patients with FMR.

P7142-AG impacts on endothelial cell activation and endothelial cell viability in vitro and impairs endothelial repair in vivo

Background

The endocannabinoid (eCB) 2-arachidonoylglycerol (2-AG) is a known modulator of inflammation and few studies have addressed its influence on myeloid cells in the context of atherogenesis. However, the impact of 2-AG on endothelial cell function has not been studied before.

Methods

Endothelial repair was studied in two treatment groups of wildtype mice following electrical denudation of the common carotid artery at a length of 3000 μm. One group received the monoacylglycerol lipase (MAGL)-inhibitor JZL184 [5 mg/kg i.p.], which impairs 2-AG degradation and thus causes elevated 2-AG levels, the other group received vehicle. The residual endothelial gap at five days in either group was visualized by Evan's blue staining. In vitro, the effect of 2-AG on human coronary artery endothelial cell (HCAEC) viability was assessed by an XTT-based assay. Endothelial activation was studied by an adhesion assay of THP-1 monocytes to 2-AG-preconditioned HCAEC. HCAEC migration, ROS-production, expression of NADPH oxidases, and secretion of inflammatory cytokines were assessed by Boyden chamber, qPCR, and colorimetric assays.

Results

Treatment with JZL184 produced a significant increase in 2-AG levels and impaired reendothelialisation in wildtype mice following electrical injury of the common carotid artery. The residual denudation at 5 days yielded 2291±286 μm in JZL184-treated animals vs. 1505±223 μm in vehicle treated controls (n=18–19; p<0.05). In vitro, JZL184 significantly reduced viability of HCAEC at 24 hours (0.31±0.10 vs. 1.00±0.08; n=3; p<0.01). Finally, 2-AG promoted HCAEC activation resulting in a significant increase in THP-1 monocyte adhesion to HCAEC following pre-treatment of HCAEC with 2-AG (0.17±0.03 THP-1 cells per HCAEC vs. 0.07±0.01 THP-1 cells per HCAEC; n=3; p<0.05). Besides, HCAEC migration, ROS-production, expression of NADPH oxidases and secretion of inflammatory cytokines were unaffected by 2-AG.

Conclusion

Elevated 2-AG levels appear to hamper endothelial repair and to promote HCAEC activation and cell death. Our data suggest that besides its influence on myeloid cells, 2-AG is also adverse to endothelial integrity which might promote early atherosclerotic lesion formation. Thus, decreasing vascular 2-AG levels might represent a promising therapeutic strategy for the prevention of atherosclerosis and coronary heart disease.

P720Atheroprotective effects of 17beta-estradiol are mediated by PPARgamma in human coronary artery smooth muscle cells

Background

17β-estradiol (E2) mediates vasculoprotection in various preclinical and clinical models of atherosclerosis and neointimal hyperplasia. However, the molecular mechanisms underlying these effects are still not fully elucidated. Previous studies have demonstrated the essential role of the peroxisome-proliferator-activated-receptor-γ (PPARγ) in mediating vasculoprotective effects of E2 in vivo. The aim of the current study was to investigate whether PPARγ is implicated in mediating vasculoprotective mechanisms of E2 in human coronary artery smooth muscle cells (HCASMC).

Methods

Primary HCASMC were purchased and stimulated with E2 [10 nM], the selective estrogen receptor α (ERα) agonist propylpyrazole triol (PPT) [50 nM] and the selective ERα antagonist methyl-piperidino-pyrazole (MPP) [1 μM], respectively. Changes in PPARγ mRNA and protein expression upon stimulation of ERα were assessed by qPCR and Western blot analyses. Nuclear PPARγ protein expression and DNA binding affinity was assessed after the isolation of the nuclear protein fraction. Hereafter, HCASMC were incubated with E2, PPARγ-antagonist GW9662 [1 μM – 30 μM], or both. HCASMC proliferation was assessed by nuclear BrdU staining and reactive oxygen species (ROS) formation was assessed by L-012- and DCF-DA assays.

Results

E2 significantly increased PPARγ expression in HCASMC (1.95±0.41 –fold; n=5; p=0.0335). This effect was mimicked by ERα agonist PPT (1.63±0.27 –fold; n=7; p=0.0489) and was abrogated by co-incubation with ERα antagonist MPP (1.17±0.18 –fold; n=3; pvs. control >0.05). Nuclear PPARγ expression was enhanced by E2 (1.53±0.16 –fold; n=4; pvs. control = 0.0074; Fig. 2A) whereas PPARγ's DNA binding activity to PPRE remained unchanged upon stimulation with E2 (0.94±0.11 –fold; n=4; pvs. control >0.05). Pharmacological inhibition of PI3K/Akt by LY294002 abrogated E2-induced expression of PPARγ (0.24±0.09 –fold; n=3; pvs. E2 = 0.0017), arguing for a PI3K/Akt-dependent activation by E2. The role of PPARγ in mediating vasculoprotective effects of E2 was assessed in functional assays using PPARγ-antagonist GW9662. E2 diminished HCASMC proliferation which was restored by GW9662. While E2 only slightly decreased ROS production by HCASMC, GW9662 significantly increased ROS levels (1,036±169 RLU x s–1 x cell–1 versus 561±99 RLU x s–1 x cell–1; n=5–6; p=0.0287).

Conclusion

In summary, the present study identifies PPARγ as a downstream mediator of E2-related atheroprotective effects in HCASMC. 17β-estradiol regulates vascular PPARγ-expression in HCASMC via the ERα receptor and the PI3K/Akt pathway. PPARγ agonism might be a promising therapeutic strategy to prevent cardiovascular events in postmenopausal women with depleted E2 plasma levels.

Acknowledgement/Funding

This work was supported by the Bonfor program of the University of Bonn [grant number O-109.0057 to JJ].

P4140Myeloid but not endothelial expression of the CB2 receptor promotes atherogenesis in the context of elevated levels of the endocannabinoid 2-arachidonoylglycerol

Background

The endocannabinoid 2-arachidonoylglycerol (2-AG) is an inflammatory mediator and ligand to the cannabinoid receptors CB1 and CB2, which are expressed on myeloid and endothelial cells. 2-AG has recently been described to promote atherogenesis in ApoE-deficient mice. While the CB2 receptor has previously been considered to solely exert anti-inflammatory and atheroprotective effects, newer data have raised the notion, that CB2 might exert atherogenic effects in the context of elevated 2-AG plasma levels. In the present study, we investigated the atherogenic mechanisms of 2-AG and the role of the CB2 receptor on myeloid and endothelial cells in atherogenesis using cell-specific knockout mouse models.

Methods

Two mouse models with atherogenic background and distinct cell-specific knockouts of the CB2 receptor on myeloid (ApoE−/−LysMcreCB2fl/fl) or endothelial cells (ApoE−/−Tie2creCB2fl/fl) were created. Mice were treated with JZL184, which inhibits 2-AG-degrading enzyme monoacylglycerol lipase, and thereby elevates 2-AG plasma levels, or with vehicle (DMSO), while being fed a high-fat diet for four weeks. Plaque volume and plaque composition were analyzed. In vitro, macrophages were treated with 2-AG and mRNA levels of adhesion molecules, scavenger receptors and chemokines, the production of reactive oxygen species (ROS) and the release of myeloperoxidase (MPO) were determined using qPCR, fluorometric assays and ELISA respectively.

Results

Elevated levels of 2-AG promote atherogenesis in ApoE-deficient mice (JZL184 vs. DMSO: 39.6±2.1% vs. 32.6±2.4%; n=14; p<0.05). The atherogenic effect of 2-AG is abrogated in mice lacking myeloid CB2 receptor expression (35.0±2.0% vs. 34.0±2.5%; n=14–16; p>0.05) but not in mice lacking endothelial CB2 receptor expression (37.1±3.1% vs. 20.9±2.6%; n=10–12; p<0.01). In vitro, 2-AG significantly increases transcription of adhesion molecule ICAM-1 (2.09±0.42 –fold; n=5–6; p<0.05), chemokine receptor CCR-1 (2.04±0.46 -fold; n=10–11; p<0.05) and scavenger receptor CD36 (8.02±1.89-fold; n=3; p<0.05) in 2-AG-treated macrophages. These effects are mitigated by pharmacological inhibition of CB2. Furthermore, 2-AG significantly increases myeloperoxidase (MPO) release in monocytes in a CB receptor-dependent fashion (451±23 pg/ml vs. 151±8.3 pg/ml; n=3–4; p<0.01) and promotes ROS production (2698±24 pdu vs. 1981±27 pdu; n=8; p<0.01).

Conclusion

Elevated 2-AG levels show an atherogenic effect in vivo which is dependent on the presence of the CB2 receptor on myeloid cells. Our in vitro data reveal 2-AG to promote pro-inflammatory signaling in macrophages and elucidate a previously unrecognized link between the endocannabinoid system and MPO in monocytes. In summary, cell-specific effects of the endocannabinoid system will have to be taken into account to facilitate its exploitation as an anti-atherosclerotic drug target.

Acknowledgement/Funding

This work was supported by the Bonfor program of the University of Bonn [grant number O-109.0057 to JJ].

P973Intravascular lithotripsy for lesion preparation in calcified coronary lesions: a prospective, observational, two-center registry

Background

Intravascular coronary lithotripsy (IVL) is a novel alternative treatment for heavily calcified lesions. This study sought to determine the strategy success and safety of IVL on calcified lesions in an all-comers cohort of patients.

Methods

Patients with moderate and severely calcified coronary lesions were screened in two centers in Spain and Germany starting April 2018. Until February 2019, 61 patients with 67 lesions were eligible for IVL. Patients were assigned to the following groups: A) Primary IVL therapy for patients with circumferential calcified de-novo coronary lesions (n=32), B) Secondary IVL therapy for patients with moderate or severe calcified coronary lesions in which conventional non-compliant balloon dilatation failed (n=18) and C) Tertiary IVL therapy in patients with in-stent stenosis due to stent underexpansion after previous stenting (n=17). Primary endpoint was strategy success and safety outcome. Strategy success was defined as successful stent delivery and expansion with attainment of <20% in-stent residual stenosis of the target lesion. Safety outcome were procedural complication, defined as coronary dissection, slow or no-reflow phenomenon, new coronary thrombus formation during PCI, abrupt vessel closure and device failure (inability to place the balloon, malfunction, or burst) and in hospital MACE.

Results

61 patients with 67 calcified lesions were treated with IVL. Mean diameter of calcified stenosis on quantitative coronary angiography was 72.02±13.8% at baseline and decreased to 17.7±15.84% (p-value: <0.01) after IVL with an acute gain of 1.9±0.63 mm. Mean minimal lumen diameter was 1.0±0.5 mm at baseline and increased after IVL to 2.9±0.6 mm. The overall average of applied pulses was 63±22. The primary endpoint of strategy success was reached overall in 85.2% of patients. 4 type b dissections (3 in group A, 1 in group B) were observed without further sequelae. There were no in-hospital MACE. In one patient (1.6%) non-ischemia driven target lesion failure was observed in routine follow up coronary angiography and was in need for revascularization. According to the subgroups, strategy success in primary IVL treatment (group A) and secondary IVL treatment (group B) was reached in 81.3% and 83.3% of cases, respectively. In tertiary IVL therapy (group C), the primary study endpoint was reached in 64.7% of cases. Device delivery and IVL treatment of target lesion could be performed in all lesions without vessel complications. 7 IVL balloons ruptured during treatment without any sequelae. Rupture was observed in most cases after repositioning of the balloon within the calcified lesion.

Conclusions

IVL provides a valid strategy for lesion preparation in severely calcified coronary lesions, with high success rate, and low procedural complication and MACE rates. Longitudinal studies will confirm if these favourable initial results of IVL-supported PCI are followed by good long-term results.

[Acute coronary syndrom as a cardiac manifestation of granulomatosis with polyangiitis]

HISTORY AND ADMISSION FINDINGS

A 49-year-old patient was admitted to our ward because of a troponin elevation (non ST-elevation myocardial infarction) following a rhinoscopy in an external hospital. The patient complained of typical angina, chronic rhinitis and epistaxis. Analysis of the nasal biopsy had shown the histological finding of granulomatosis with polyangiitis (Wegener's granulomatosis).

INVESTIGATION

The consecutively performed catheterization showed a coronary one-vessel disease without significant stenosis. Echocardiography showed diastolic dysfunction as well as hemodynamically not significant pericardial effusion. The MRI scan of the heart revealed multiple myocardial scars located ventricular apical and septal. Extended bilateral pulmonary opacities in the thoracic CT scan, microhematuria, leukocyturia and proteinuria indicated multi-organ involvement of the small vessel disease.

TREATMENT AND COURSE

The patient's condition improved quickly in response to steroids and cyclophosphamide, followed by attenuation of clinical symptoms and normalizing blood and renal parameters.

CONCLUSION

The prognosis of granulomatosis with polyangiitis is mainly limited by renal and pulmonal involvement. Cardiac involvement is commonly rare and associated with clinical courses refractory to immunosuppressive therapy. Generally, all cardiac structures can be affected, thereby impending serious cardiac events. Normally, granulomatosis with polyangiitis responds quickly to immunosuppressive therapy, associated with a rather good prognosis without higher mortality.

[Acute coronary syndrome as a first manifestation of Churg-Strauss syndrome]

HISTORY AND ADMISSION FINDINGS

A 53-year-old woman was admitted to our chest pain unit because of an acute coronary syndrome (non ST-elevation myocardial infarction). She complained of asthma, chronic sinusitis and involuntary weight loss, occasional fever and night sweats over the past six months.

INVESTIGATIONS

Coronary angiography did not show any signs of macroscopic coronary artery disease, while echocardiography demonstrated a hemodynamically not significant pericardial effusion. Magnetic resonance imaging of the heart revealed a subendocardial scar, extension and localization pointing to a vascular genesis. Thoracic computed tomography revealed pulmonary opacities and blood tests showed an eosinophilia, leading to the clinical diagnosis of Churg-Strauss syndome.

TREATMENT AND COURSE

The patient responded quickly to oral steroids, and blood parameters returned to normal.

CONCLUSION

Acute coronary syndrome in youngish patients without classical cardiovascular risk factors is suggestive for myocarditis but also for vasculitis. Churg-Strauss syndrome usually responds quickly to immunosuppressive therapy, associated with a rather good prognosis without high mortality.

[Unclear acute respiratory failure in a 64-year-old woman after coronary intervention]

HISTORY AND ADMISSION FINDINGS

Due to a retroperitoneal hematoma after cardiac catheterization a 64 year-old woman received two concentrates of red blood cells. Within two hours after transfusion the patient developed acute dyspnoea, anxiety and shivering.

INVESTIGATIONS

Computertomography (CT) of the chest revealed a new bilateral, basally accented pulmonary edema. Pulmonary embolism was ruled out. A cardiac cause in terms of cardiogenic shock had been excluded by echocardiography and other non-invasive measurements. Moreover, no circulatory overload (transfusion-associated circulatory overload [TACO]) after transfusion was presented and the stable size of the retroperitoneal hematoma excluded haemorrhagic shock. Hence, the clinical pattern pointed towards a transfusion-related acute lung injury (TRALI).

TREATMENT AND COURSE

The patient was intubated and a catecholamine medication was initiated. The weaning process proceeded without complications and the patient was extubated after several days. In the following chest x-ray no pulmonary residuals were left. After two weeks the patient was transferred to a rehabilitation unit.

CONCLUSION

TRALI is a life-threatening and an often unconsidered complication after transfusion of plasma containing blood products. According to the criteria of the european haemovigilance networks (EHN-criteria), TRALI is diagnosed by clinical and radiological parameters. In case of suspicious TRALI the involved transfusion center has to be informed. By a crossmatch between donor plasma and recipient granulocytes the causal antibodies are detected in most cases. In 17% of cases no antibodies are detected.