Plasma Cholesterol-Induced Lesion Networks Activated before Regression of Early, Mature, and Advanced Atherosclerosis

Plasma cholesterol lowering (PCL) slows and sometimes prevents progression of atherosclerosis and may even lead to regression. Little is known about how molecular processes in the atherosclerotic arterial wall respond to PCL and modify responses to atherosclerosis regression. We studied atherosclerosis regression and global gene expression responses to PCL (>= 80%) and to atherosclerosis regression itself in early, mature, and advanced lesions. In atherosclerotic aortic wall from Ldlr(-/-)Apob(100/100)Mttp(flox/flox)Mx1-Cre mice, atherosclerosis regressed after PCL regardless of lesion stage. However, near-complete regression was observed only in mice with early lesions; mice with mature and advanced lesions were left with regression-resistant, relatively unstable plaque remnants. Atherosclerosis genes responding to PCL before regression, unlike those responding to the regression itself, were enriched in inherited risk for coronary artery disease and myocardial infarction, indicating causality. Inference of transcription factor (TF) regulatory networks of these PCL-responsive gene sets revealed largely different networks in early, mature, and advanced lesions. In early lesions, PPARG was identified as a specific master regulator of the PCL-responsive atherosclerosis TF-regulatory network, whereas in mature and advanced lesions, the specific master regulators were MLL5 and SRSF10/XRN2, respectively. In a THP-1 foam cell model of atherosclerosis regression, siRNA targeting of these master regulators activated the time-point-specific TF-regulatory networks and altered the accumulation of cholesterol esters. We conclude that PCL leads to complete atherosclerosis regression only in mice with early lesions. Identified master regulators and related PCL-responsive TF-regulatory networks will be interesting targets to enhance PCL-mediated regression of mature and advanced atherosclerotic lesions. Author Summary The main underlying cause of heart attacks and strokes is atherosclerosis. One strategy to prevent these often deadly clinical events is therefore either to slow atherosclerosis progression or better, induce regression of atherosclerotic plaques making them more stable. Plasma cholesterol lowering (PCL) is the most efficient way to induce atherosclerosis regression but sometimes fails to do so. In our study, we used a mouse model with elevated LDL cholesterol levels, similar to humans who develop early atherosclerosis, and a genetic switch to lower plasma cholesterol at any time during atherosclerosis progression. In this model, we examined atherosclerosis gene expression and regression in response to PCL at three different stages of atherosclerosis progression. PCL led to complete regression in mice with early lesions but was incomplete in mice with mature and advanced lesions, indicating that early prevention with PCL in individuals with increased risk for heart attack or stroke would be particularly useful. In addition, by inferring PCL-responsive gene networks in early, mature and advanced atherosclerotic lesions, we identified key drivers specific for regression of early (PPARG), mature (MLL5) and advanced (SRSF10/XRN2) atherosclerosis. These key drivers should be interesting therapeutic targets to enhance PCL-mediated regression of atherosclerosis

Increased expression of inactive rhomboid protein 2 in circulating monocytes after acute myocardial infarction

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Deutsche Forschungsgemeinschaft (DFG; Sachbeihilfe HE6092/2) DGK (Deutsche Gesellschaft für Kardiologie) Otto-Hess-Promotionsstipendium Purpose Tumor necrosis factor-alpha (TNF-α) levels in the blood increase in the course of an acute myocardial infarction (AMI) and TNF-α is involved in the impaired recovery of myocardial function following AMI. The interaction of inactive rhomboid protein 2 (iRhom2) with the TNF-α converting enzyme (TACE) is required for the proper shedding of TNF-α from the cell surface of immune cells. We hypothesized, that iRhom2 expression increases in circulating monocytes of patients following AMI.  Methods Circulating monocytes were MACS-sorted from peripheral blood of 50 patients with AMI (NSTEMI, n = 16; STEMI n = 34) at the day of admission (day 1) and 3 days after admission. 50 patients with chronic coronary syndrome (CCS) were recruited as control. mRNA was isolated from sorted monocytes and expression levels of iRhom2, TACE and TNF-α were evaluated by real-time RT-PCR. TNF-α protein levels were assessed in the serum. Levels of circulating classical, intermediate and non-classical monocyte subsets were determined by flow cytometry.  Results There was a significant increase of iRhom2 mRNA expression levels in monocytes (by 14%, p = 0.012), levels of circulating intermediate monocytes (p &amp;lt; 0.001), and TNF-α serum levels (p &amp;lt; 0.001) at day 3 following AMI compared to day 1 reaching levels similar to those observed in CCS patients. In contrast, TNF-α and TACE mRNA expression in circulating monocytes did not differ between day 1 and 3 following AMI. iRhom2 mRNA expression in monocytes on day 3 following AMI correlated with TACE mRNA expression in monocytes (r = 0.72, p &amp;lt; 0.001), TNF-α serum levels (r = 0.33, p = 0.019), and levels of circulating intermediate monocytes (r = 0.37, p = 0.009). Conclusions Following AMI, iRhom2 expression in circulating monocytes increases in parallel to serum levels of TNF-α and levels of circulating intermediate monocytes. These findings suggest that iRhom2 contributes to inflammation following AMI and thus may serve as a potential therapeutic target. </jats:sec

Impact of caval vein implantation on severity of tricuspid regurgitation, renal and hepatic function in patients with severe secondary tricuspid regurgitation

Abstract Background Severe tricuspid regurgitation (TR) is an important determinant for functional capacity and survival. It frequently occurs in patients with advanced heart failure resulting in progressive venous congestion with cardiorenal and cardiohepatic syndrome. The prospective, randomized TRICAVAL study reported the effect of inferior caval vein implantation of an Edwards Sapien XT valve (CAVI) in comparison to optimal medical therapy (OMT) in patients with severe TR. The study did not detect a superior functional outcome after CAVI, but a significant improvement in quality of life. Due to safety concerns, the study was stopped prematurely after 4 periprocedural complications. Purpose We hypothesised that CAVI reduces reflux into the inferior vena cava and leads to an increase in systolic right atrial pressure, which may result in an improvement of TR severity. The present subanalysis of the TRICAVAL study evaluates the impact of inferior caval vein implantation on TR severity, right heart parameters and renal and hepatic function. Methods Twenty-eight patients with severe TR were randomized in either CAVI group (n=14) with caval vein implantation of an Edwards Sapien XT valve or OMT group (n=14). Medical history, clinical examination, laboratory testing and echocardiographic measurements were analysed in patients with completed FUP (OMT [n = 10], CAVI [n = 8]). Follow-up examinations were performed at baseline and three months after enrolment. Results After three months, the CAVI group exhibited a significant reduction of systolic hepatic vein reflux volume (5.0 [1.3–11.0] ml vs. 14.0 [10.3–18.0] ml, p&amp;lt;0.05) and hepatic vein diameter (10.8 [10.0–12.0] mm vs. 14.0 [11.5–15.0] mm, p&amp;lt;0.05) in comparison to OMT. Compared to baseline, CAVI improved body weight (80.7 [69.0–87.7] kg versus 75.5 [63.8–84.6] kg, p&amp;lt;0.05) and abdominal circumference (101.5±13.8 cm versus 96.3±15.4 cm, p≤0.01) paralleled by a trend to lower doses of diuretics. However, over the FUP period, there were no significant changes regarding TR severity, right heart function and morphology as well as renal and hepatic function within both groups, nor in the comparison between CAVI and OMT. Conclusion As a proof of our concept, CAVI resulted in a decrease in systolic hepatic vein reflux, hepatic vein diameter and clinical signs of venous congestion. However, TR severity, right heart function and morphology as well as renal and hepatic function remained stable. Funding Acknowledgement Type of funding source: Private company. Main funding source(s): Edwards Lifesciences, Incorporated (Irvine, CA) </jats:sec

Salt bridges in the miniature viral channel Kcv are important for function

The viral potassium channel Kcv comprises only 94 amino acids, which represent the pore module of more complex K+ channels. As for Kir-type channels, Kcv also has a short N-terminal helix exposed to the cytoplasm, upstream of the first transmembrane domain. Here we show that this helix is relevant for Kcv function. The presence of charged amino acids, which form dynamic inter- and intra-subunit salt bridges is crucial. Electrophysiological measurements, yeast rescue experiments and molecular dynamics simulations show that mutants in which the critical salt bridge formation is impaired have no or reduced channel activity. We conclude that these salt bridges destabilise the complexation of K+ ions by negative charges on the inner transmembrane domain at the entrance into the cavity. This feature facilitates a continuous and coordinated transfer of ions between the cavity and the cytoplasm for channels without the canonical bundle crossing

Hypoxia Induces Netrin-1 and Unc5b in Atherosclerotic Plaques Mechanism for Macrophage Retention and Survival

Nephrolog

Neuroimmune Guidance Cue Semaphorin 3E Is Expressed in Atherosclerotic Plaques and Regulates Macrophage Retention

Nephrolog