Targeting deubiquitinase OTUB1 protects vascular smooth muscle cells in atherosclerosis by modulating PDGFRß.

Atherosclerosis is a chronic artery disease that causes various types of cardiovascular dysfunction. Vascular smooth muscle cells (VSMCs), the main components of atherosclerotic plaque, switch from contractile to synthetic phenotypes during atherogenesis. Ubiquitylation is crucial in regulating VSMC phenotypes in atherosclerosis, and it can be reversely regulated by deubiquitinases. However, the specific effects of deubiquitinases on atherosclerosis have not been thoroughly elucidated. In this study, RNAi screening in human aortic smooth muscle cells was performed to explore the effects of OTU family deubiquitinases, which revealed that silencing OTUB1 inhibited PDGF-BB-stimulated VSMC phenotype switch. Further in vivo studies using Apoe-/- mice revealed that knockdown of OTUB1 in VSMCs alleviated atherosclerosis plaque burden in the advanced stage and led to a stable plaque phenotype. Moreover, VSMC proliferation and migration upon PDGF-BB stimulation could be inhibited by silencing OTUB1 in vitro. Unbiased RNA-sequencing data indicated that knocking down OTUB1 influenced VSMC differentiation, adhesion, and proliferation. Mass spectrometry of ubiquitinated protein confirmed that proteins related to cell growth and migration were differentially ubiquitylated. Mechanistically, we found that OTUB1 recognized the K707 residue ubiquitylation of PDGFRß with its catalytic triad, thereby reducing the K48-linked ubiquitylation of PDGFRß. Inhibiting OTUB1 in VSMCs could promote PDGFRß degradation via the ubiquitin-proteasome pathway, so it was beneficial in preventing VSMCs' phenotype switch. These findings revealed that knocking down OTUB1 ameliorated VSMCs' phenotype switch and atherosclerosis progression, indicating that OTUB1 could be a valuable translational therapeutic target in the future.

A novel intracoronary hypothermia device reduces myocardial reperfusion injury in pigs.

BACKGROUND: Hypothermia therapy has been suggested to attenuate myocardial necrosis; however, the clinical implementation as a valid therapeutic strategy has failed, and new approaches are needed to translate into clinical applications. This study aimed to assess the feasibility, safety, and efficacy of a novel selective intracoronary hypothermia (SICH) device in mitigating myocardial reperfusion injury. METHODS: This study comprised two phases. The first phase of the SICH was performed in a normal porcine model for 30 minutes ( n = 5) to evaluate its feasibility. The second phase was conducted in a porcine myocardial infarction (MI) model of myocardial ischemia/reperfusion was performed by balloon occlusion of the left anterior descending coronary artery for 60 minutes and maintained for 42 days. Pigs in the hypothermia group ( n = 8) received hypothermia intervention onset reperfusion for 30 minutes and controls ( n = 8) received no intervention. All animals were followed for 42 days. Cardiac magnetic resonance analysis (5 and 42 days post-MI) and a series of biomarkers/histological studies were performed. RESULTS: The average time to lower temperatures to a steady state was 4.8 ± 0.8 s. SICH had no impact on blood pressure or heart rate and was safely performed without complications by using a 3.9 F catheter. Interleukin-6 (IL-6), tumor necrosis factor-α, C-reactive protein (CRP), and brain natriuretic peptide (BNP) were lower at 60 min post perfusion in pigs that underwent SICH as compared with the control group. On day 5 post MI/R, edema, intramyocardial hemorrhage, and microvascular obstruction were reduced in the hypothermia group. On day 42 post MI/R, the infarct size, IL-6, CRP, BNP, and matrix metalloproteinase-9 were reduced, and the ejection fraction was improved in pigs that underwent SICH. CONCLUSIONS: The SICH device safely and effectively reduced the infarct size and improved heart function in a pig model of MI/R. These beneficial effects indicate the clinical potential of SICH for treatment of myocardial reperfusion injury.

Are baseline conditions of coronary arteries sufficient for calculating angio-based index of microcirculatory resistance and fractional flow reserve?

Background: Angio-based index of microcirculatory resistance (IMR) and fractional flow reserve (FFR) have been developed, however, the differences between baseline and hyperemic data and their effects on their computation have not yet been discussed. This study aimed to compare the diagnostic performance of a novel method for calculating IMR and FFR from coronary angiography under baseline and hyperemic conditions. Methods: We performed a retrospective study to investigate the diagnostic performance of angiography-derived IMR (AccuIMR) and FFR (AccuFFRangio) computed from the hyperemic condition (AccuIMRhyp, AccuFFRangiohyp) and baseline condition (AccuIMRbase, AccuFFRangiobase) in 101 consecutive patients with chronic coronary syndrome (CCS) who underwent measurements of IMR and FFR at a single center, using wire-based IMR and FFR as the reference standard. Results: AccuIMRhyp showed much better correlation with IMR than AccuIMRbase (r=0.77 vs. 0.47, P<0.001). The diagnostic accuracy and area under the curve (AUC) for identifying significant microvascular dysfunction was higher for AccuIMRhyp than AccuIMRbase [92.1% (95% CI: 85.0-96.5%) vs. 83.2% (95% CI: 74.4-89.9%), P=0.012; 0.942 (95% CI: 0.877-0.979) vs. 0.815 (95% CI: 0.726-0.886), P=0.003]. The computed AccuFFRangio showed good correlations with FFR and good diagnostic performance under both hyperemic and baseline conditions [r=0.68 vs. 0.68, P>0.99; diagnostic accuracy =95.9% (95% CI: 89.8-98.9%) vs. 94.9% (95% CI: 88.4-98.3%), P=0.728; AUC =0.989 (95% CI: 0.942-1.000) vs. 0.973 (95% CI: 0.919-0.995), P=0.381]. The net reclassification index (NRI) demonstrated that hyperemic group had improved reclassification ability compared to the baseline group in identification of IMR >25 (NRI =0.20, P<0.001) and FFR ≤0.8 (NRI =0.11, P<0.001). Conclusions: By comparing the calculated angio-derived IMR and FFR under the baseline and hyperemic conditions, this study demonstrates that AccuIMR calculation is more accurate using the hyperemic condition, while AccuFFRangio calculation is accurate under both conditions.

Semaphorin3A Exacerbates Cardiac Microvascular Rarefaction in Pressure Overload-Induced Heart Disease.

Microvascular endothelial cells (MiVECs) impair angiogenic potential, leading to microvascular rarefaction, which is a characteristic feature of chronic pressure overload-induced cardiac dysfunction. Semaphorin3A (Sema3A) is a secreted protein upregulated in MiVECs following angiotensin II (Ang II) activation and pressure overload stimuli. However, its role and mechanism in microvascular rarefaction remain elusive. The function and mechanism of action of Sema3A in pressure overload-induced microvascular rarefaction, is explored, through an Ang II-induced animal model of pressure overload. RNA sequencing, immunoblotting analysis, enzyme-linked immunosorbent assay, quantitative reverse transcription polymerase chain reaction (qRT-PCR), and immunofluorescence staining results indicate that Sema3A is predominantly expressed and significantly upregulated in MiVECs under pressure overload. Immunoelectron microscopy and nano-flow cytometry analyses indicate small extracellular vesicles (sEVs), with surface-attached Sema3A, to be a novel tool for efficient release and delivery of Sema3A from the MiVECs to extracellular microenvironment. To investigate pressure overload-mediated cardiac microvascular rarefaction and cardiac fibrosis in vivo, endothelial-specific Sema3A knockdown mice are established. Mechanistically, serum response factor (transcription factor) promotes the production of Sema3A; Sema3A-positive sEVs compete with vascular endothelial growth factor A to bind to neuropilin-1. Therefore, MiVECs lose their ability to respond to angiogenesis. In conclusion, Sema3A is a key pathogenic mediator that impairs the angiogenic potential of MiVECs, which leads to cardiac microvascular rarefaction in pressure overload-induced heart disease.

Critical Role of the cGAS-STING Pathway in Doxorubicin-Induced Cardiotoxicity.

BACKGROUND: Doxorubicin is an effective chemotherapy drug for treating various types of cancer. However, lethal cardiotoxicity severely limits its clinical use. Recent evidence has indicated that aberrant activation of the cytosolic DNA-sensing cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS)-STING (stimulator of interferon genes) pathway plays a critical role in cardiovascular destruction. Here, we investigate the involvement of this mechanism in doxorubicin-induced cardiotoxicity (DIC). METHODS: Mice were treated with low-dose doxorubicin to induce chronic DIC. The role of the cGAS-STING pathway in DIC was evaluated in cGAS-deficiency (cGAS-/-), Sting-deficiency (Sting-/-), and interferon regulatory factor 3 (Irf3)-deficiency (Irf3-/-) mice. Endothelial cell (EC)-specific conditional Sting deficiency (Stingflox/flox/Cdh5-CreERT) mice were used to assess the importance of this pathway in ECs during DIC. We also examined the direct effects of the cGAS-STING pathway on nicotinamide adenine dinucleotide (NAD) homeostasis in vitro and in vivo. RESULTS: In the chronic DIC model, we observed significant activation of the cGAS-STING pathway in cardiac ECs. Global cGAS, Sting, and Irf3 deficiency all markedly ameliorated DIC. EC-specific Sting deficiency significantly prevented DIC and endothelial dysfunction. Mechanistically, doxorubicin activated the cardiac EC cGAS-STING pathway and its target, IRF3, which directly induced CD38 expression. In cardiac ECs, the cGAS-STING pathway caused a reduction in NAD levels and subsequent mitochondrial dysfunction via the intracellular NAD glycohydrolase (NADase) activity of CD38. Furthermore, the cardiac EC cGAS-STING pathway also regulates NAD homeostasis and mitochondrial bioenergetics in cardiomyocytes through the ecto-NADase activity of CD38. We also demonstrated that pharmacological inhibition of TANK-binding kinase 1 or CD38 effectively ameliorated DIC without compromising the anticancer effects of doxorubicin. CONCLUSIONS: Our findings indicate a critical role of the cardiac EC cGAS-STING pathway in DIC. The cGAS-STING pathway may represent a novel therapeutic target for preventing DIC.

Usefulness of catestatin to predict malignant arrhythmia in patients with acute myocardial infarction.

Catestatin (CST) displays potent vasodilatory effect and acts on lowering blood pressure in vivo. The clinical utility of CST in patients with acute myocardial infarction (AMI) has not been clearly delineated. The aim of this study was to investigate the predictive value of CST for the development of in-hospital malignant arrhythmia and other adverse cardiac events in patients with AMI. A total of 125 consecutive patients diagnosed with AMI were included. The clinical characteristics and previous history of the patients were collected. Malignant arrhythmia and other major adverse cardiac events (MACE) such as postinfarction angina pectoris or reinfarction and death were recorded during hospitalization. The levels of plasma CST, norepinephrine (NE) and amino-terminal pro-brain sodium peptides (NT-proBNP) were determined by sandwich ELISA. A multiple logistic regression model was used to predict the influence factors of malignant arrhythmia and other MACE during hospitalization of AMI patients. The results showed that the levels of plasma cystatin-C (CysC), high sensitivity C-reactive protein (hs-CRP), NE and NT-proBNP increased in a CST concentration dependent manner. The incidence of malignant arrhythmia significantly increased as the elevation of CST level (P<0.05). Age, CST and NT-proBNP were independent predictors for the MACE occurred during hospitalization. Increased blood glucose (≥6.1mmol/L) and CST were independent predictors for the complicated malignant arrhythmia of AMI patients. These data demonstrated that CST can be used as a new biological marker for prediction of malignant arrhythmia in patients with AMI.

[Prognostic value of circulating catestatin levels for in-hospital heart failure in patients with acute myocardial infarction].

OBJECTIVE: To determine whether circulating level of catestatin (CST) could provide prognostic information independently of conventional risk markers for the development of in-hospital heart failure in patients with ST-segment elevation myocardial infarction (STEMI). METHODS: The data of 120 STEMI patients (mean age: 61 years, 73% male) were collected from the Second Hospital of Shanxi Medical University and Taiyuan Central Hospital between November 2010 and September 2011.The patients were categorized into 4 groups according to CST (ng/L) quartile: ≤ 74.72, 74.73-79.67, 79.68 - 84.21 and ≥ 84.22 ng/L. Clinical features, therapeutic approaches were compared among groups. The patients were also grouped according to Killip class: Killip level I (n = 68), Killip level II (n = 23), Killip level III (n = 18), Killip level IV (n = 11). CST, NE and NT-proBNP were compared among groups. The Spearma rank correlation and multivariate logistic regression analysis were applied to determine the association between risk factors and in-hospital heart failure. Receiver-operator characteristic (ROC) curve was performed to evaluate the power of CST and NT-proBNP on predicting in-hospital heart failure. RESULTS: Gender, hospital days, past history of smoking, hypertension, myocardial infarction, CK-MB peak level, TnI peak level, heart rate, blood pressure, blood glucose, blood lipid levels on admission and early reperfusion therapy were similar among groups. Patients with higher CST values were more likely to be older, to have lower body mass index, to have higher white blood cell count, CysC, hs-CRP, NE, NT-proBNP, past history of angina, diabetes mellitus, being diuretic users, and to have a lower ejection fraction (all P < 0.05). Higher CST levels were also associated with increased risk of heart failure (P < 0.05). In proportion with the deterioration of the cardiac function, CST, NE, NT-proBNP concentration gradually increased (all P < 0.05). Spearman rank correlation analysis showed that the CST was negatively correlated with LVEF (r(s) = -0.923, P < 0.001) and positively correlated with NT-proBNP (r(s) = 0.884, P < 0.001). After multivariate adjustment, CST remained to be an independent risk factor for the development of in-hospital heart failure (OR = 1.125, 95%CI: 1.056 - 1.198;P < 0.001). The area under the ROC curve of CST and NT-proBNP was 0.777 and 0.874. Using CST = 77.29 ng/L as a cut-off value, the sensitivity was 92.8% and specificity was 70.6% for predicting the development of in-hospital heart failure. CONCLUSION: The plasma CST level is an independent predictor for the development of in-hospital heart failure in patients with STEMI.