Novel findings: Expression of angiotensin-converting enzyme and angiotensin-converting enzyme 2 in thoracic aortic dissection and aneurysm

ACE2 deficiency inhibits thoracic aortic dissection by enhancing SIRT3 mediated inhibition of inflammation and VSCMs phenotypic switch

BACKGROUND

Thoracic aortic dissection (TAD) is an irreversible cardiovascular disorder with high mortality and morbidity. However, the molecular mechanisms remain elusive. Thus, identifying an effective therapeutic target to prevent TAD is especially critical. The purpose of this study is to elucidate the potential mechanism of inflammation and vascular smooth muscle cell (VSMCs) phenotypic switch in β-aminopropionitrile fumarate (BAPN)-induced TAD.

METHODS

A mouse model of TAD induced by BAPN and IL-1β -stimulated HVSMCs in vivo and in vitro models, respectively. ACE2 Knockdown mice treated with BAPN or without, and the TAD mouse model was treated with or without AAV-ACE2. Transthoracic ultrasound was conducted for assessment the maximum internal diameter of the thoracic aorta arch. RNA sequencing analysis was performed to recapitulate transcriptome profile changes. Western blot were used to detect the expression of MMP2, MMP9, ACE2, SIRT3, OPN, SM22α and other inflammatory markers. The circulating levels of ACE2 was measured by ELISA assay. Histological changes of thoracic aorta tissues were assessed by H&E, EVG and IHC analysis.

RESULTS

We found that circulating levels of and the protein levels of ACE2 were increased in the TAD mouse model and in patients with TAD. For further evidence, ACE2 deficiency decelerated the formation of TAD. However, overexpression of ACE2 aggravated BAPN-induced aortic injury and VSMCs phenotypic switch via lowered SIRT3 expression and elevated inflammatory cytokine expression.

CONCLUSION

ACE2 deficiency prevented the development of TAD by inhibiting inflammation and VSMCs phenotypic switch in a SIRT3-dependent manner, suggesting that the ACE2/SIRT3 signaling pathway played a pivotal role in the pathological process of TAD and might be a potential therapeutical target.

Preoperative blood urea nitrogen-to-serum albumin ratio for prediction of in-hospital mortality in patients who underwent emergency surgery for acute type A aortic dissection

The study aimed to assess the predictive value of blood urea nitrogen (BUN)-to-albumin ratio (BA-R) for in-hospital mortality in patients undergoing emergency surgery for acute type A aortic dissection (ATAAD). Patients who were diagnosed with ATAAD and underwent emergency surgery within 48 hours of onset at our hospital between January 2015 and December 2021 were included in this study. The primary endpoint of this study was postoperative in-hospital mortality (POIM). The data of the survivors and non-survivors were retrospectively compared analyses. A total of 557 ATAAD patients were included, with 505 survivors and 52 non-survivors. The preoperative BA-R of the non-survivor group was significantly higher than that of the survivor group (P < 0.001). Univariate regression analysis showed that preoperative BA-R, serum creatinine level, SA level, D-dimer level, age, myocardial ischemia, cerebral ischemia, and aortic clamp time were risk factors for POIM. In addition, multivariable regression analysis showed that preoperative BA-R ≥ 0.155 mmol/g was a risk factor for POIM (odds ratio, 6.815 [3.582-12.964]; P < 0.001). Receiver operating characteristic curve indicated that the cut-off point for preoperative BA-R was ≥0.155 mmol/g (area under the curve =0.874). The sensitivity and specificity of preoperative BA-R in predicting the POIM of patients who underwent emergency surgery for ATAAD were 84.6% and 71.3%, respectively (95% confidence interval, 0.829-0.919; P < 0.001). In conclusion, Preoperative BA-R is a simple, rapid, and potentially useful prognostic indicator of POIM in patients with ATAAD. BAR: Blood urea nitrogen-to-albumin ratio, BUN: Blood urea nitrogen, SA: Serum albumin, REF: Reference. The aim of this study was to evaluate the prognostic value of BA-R for the prediction of postoperative in-hospital mortality in patients who underwent emergency surgery for ATAAD. A total of 557 patients with ATAAD were enrolled, and 505 survived while 52 did not. The preoperative BA-R of the non-survivor group was significantly higher than that of the survivor group (0.27 [0.18, 0.46] vs. 0.12 [0.10, 0.16]mmol/g; P < 0.001). The study showed that preoperative BA-R ≥ 0.155 mmol/g was a risk factor for POIM (odds ratio, 6.815 [3.582-12.964]; P < 0.001). ROC curve indicated that the cut-off point for preoperative BA-R was ≥0.155 mmol/g (AUC = 0.874) and the sensitivity and specificity were 84.6% and 71.3%, respectively (95% CI, 0.829-0.919; P < 0.001). We believe that our study makes a significant contribution to the literature because we found preoperative BA-R to be a simple, rapid, and potentially useful prognostic indicator of postoperative in-hospital mortality in patients with ATAAD.

A comprehensive exploration of novel biomarkers for the early diagnosis of aortic dissection

Aortic dissection (AD) is a catastrophic life-threatening cardiovascular emergency with a 1-2% per hour mortality rate post-diagnosis, characterized physiologically by the separation of aortic wall layers. AD initially presents as intense pain that can then radiate to the back, arms, neck, or jaw along with neurological deficits like difficulty in speaking, and unilateral weakness in some patients. This spectrum of clinical features associated with AD is often confused with acute myocardial infarction, hence leading to a delay in AD diagnosis. Cardiac and vascular biomarkers are structural proteins and microRNAs circulating in the bloodstream that correlate to tissue damage and their levels become detectable even before symptom onset. Timely diagnosis of AD using biomarkers, in combination with advanced imaging diagnostics, will significantly improve prognosis by allowing earlier vascular interventions. This comprehensive review aims to investigate emerging biomarkers in the diagnosis of AD, as well as provide future directives for creating advanced diagnostic tools and imaging techniques.

The creation and validation of predictive models to assess the risk of unfavorable outcomes following hybrid total arch repair for Stanford type A aortic dissection

BACKGROUND

The objective of this study was to develop and validate a nomogram for the individualized prediction of adverse events in patients with Stanford type A aortic dissection (TAAD) undergoing hybrid total aortic arch repair.

METHODS

From April 2019 to April 2022, we conducted a comprehensive review of the medical records of Stanford type A aortic dissection patients who underwent hybrid total aortic arch repair surgery at our hospital. Patients were separated into two groups based on whether or not a composite adverse event occurred following surgery. Using univariate and multivariate analyses of logistic regression, the prediction model was created. Construct risk prediction models utilizing nomograms and evaluate their precision, discrimination, and clinical utility.

RESULTS

Age, platelets, serum blood urea nitrogen, and ascending aortic diameter were the variables included in the nomogram by univariate and multivariate analysis. The risk model performed well in internal validation, with an area under the curve (AUC) of 0.829. The calibration curve demonstrated good agreement between predicted and actual probabilities (Hosmer-Lemeshow test, P = 0.22). Clinical decision analysis curves demonstrate predictive nomograms' clinical utility.

CONCLUSION

This study created and validated a nomogram for predicting the risk of composite endpoint events in TAAD patients undergoing hybrid total aortic arch repair. The nomogram can help determine the severity of a patient's condition and provide a more personalized diagnosis and treatment.

The Maastricht Acquisition Platform for Studying Mechanisms of Cell-Matrix Crosstalk (MAPEX): An Interdisciplinary and Systems Approach towards Understanding Thoracic Aortic Disease

Current management guidelines for ascending thoracic aortic aneurysms (aTAA) recommend intervention once ascending or sinus diameter reaches 5-5.5 cm or shows a growth rate of >0.5 cm/year estimated from echo/CT/MRI. However, many aTAA dissections (aTAAD) occur in vessels with diameters below the surgical intervention threshold of <55 mm. Moreover, during aTAA repair surgeons observe and experience considerable variations in tissue strength, thickness, and stiffness that appear not fully explained by patient risk factors. To improve the understanding of aTAA pathophysiology, we established a multi-disciplinary research infrastructure: The Maastricht acquisition platform for studying mechanisms of tissue-cell crosstalk (MAPEX). The explicit scientific focus of the platform is on the dynamic interactions between vascular smooth muscle cells and extracellular matrix (i.e., cell-matrix crosstalk), which play an essential role in aortic wall mechanical homeostasis. Accordingly, we consider pathophysiological influences of wall shear stress, wall stress, and smooth muscle cell phenotypic diversity and modulation. Co-registrations of hemodynamics and deep phenotyping at the histological and cell biology level are key innovations of our platform and are critical for understanding aneurysm formation and dissection at a fundamental level. The MAPEX platform enables the interpretation of the data in a well-defined clinical context and therefore has real potential for narrowing existing knowledge gaps. A better understanding of aortic mechanical homeostasis and its derangement may ultimately improve diagnostic and prognostic possibilities to identify and treat symptomatic and asymptomatic patients with existing and developing aneurysms.

Role and interaction between ACE1, ACE2 and their related genes in cardiovascular disorders

Cardiovascular disease is the greatest health care burden and one of the most common causes of death worldwide. Less is known about the genetic factors that are responsible for predisposition to cardiovascular disease thus; the molecular and genetic mechanisms underlying cardiovascular diseases remain obscure. One important regulator of blood pressure homeostasis is the renin-angiotensin system (RAS). The protease renin cleaves angiotensinogen into the inactive decameric peptide angiotensin I (AngI). Angiotensin-converting enzyme (ACE) catalyzes the cleavage of the Ang I into the active octomer angiotensin II (Ang II). In humans, can ACE polymorphism has been associated with determinants of renal and cardiovascular function and pharmacological inhibition of ACE and Ang II receptors are effective in lowering blood pressure and preventing kidney disease. In addition, inhibition of ACE and Ang II receptors has beneficial effects in heart failure. A homologue of ACE, termed ACE2, has been identified; it is predominantly expressed in the vascular endothelial cells of the kidney and heart. Unlike ACE, ACE2 functions as a carboxypeptidase, cleaving a single residue from AngI, generating Ang1-9, and a single residue from AngII to generate Ang1-7. Nevertheless, the in vivo role of ACE2 in the cardiovascular system and the RAS is not known.

Is there a role for biomarkers in thoracic aortic aneurysm disease?

Thoracic aortic aneurysm (TAA) represents a major cause of mortality and morbidity in Western countries. The natural history of TAA is indolent, with patients usually being asymptomatic until a catastrophic event such as rupture or dissection ensues. As such, early diagnosis is crucial and the search is ongoing for a biomarker that can indicate the presence of TAA with sufficient accuracy to act as a screening tool. To date, no such marker has been developed for the diagnosis of non-familial or 'sporadic' TAA. However, our increased understanding of the pathogenesis of both familial and sporadic TAA has suggested potential candidates for diagnostic biomarkers. Many markers/pathways have been shown to have differential activity levels or expression in the aortic tissue of TAA. However, priority is given to markers that have shown differential levels in blood plasma, as blood tests represent the easiest route for mass screening for TAA. This review aims to evaluate the efficacy of clinical tests already in use in diagnosing TAA, explore novel proposed biomarkers and identify key areas of future interest.

The polymorphisms in angiotensin-converting enzyme and angiotensin-converting enzyme 2 are not associated with thoracic aortic diseases and coronary heart disease

Introduction:

The polymorphisms of the angiotensin-converting enzyme (ACE) and angiotensin-converting enzyme 2 (ACE2) genes have been demonstrated to be involved in some cardiovascular diseases. We hypothesised that the polymorphisms of ACE and ACE2 relate to the formation of thoracic aortic diseases and coronary heart disease.

Methods:

A total of 86 patients (four groups: thoracic aortic dissection; thoracic aortic aneurysm; coronary heart disease; and control group) were recruited. The ACE I/D polymorphism and the ACE2 (A8790G) polymorphism were measured in all patient samples.

Results:

There were no significant differences in groups with regard to either the ACE I/D polymorphism or the ACE2 (A8790G) polymorphism.

Conclusion:

The polymorphisms of the ACE and ACE2 genes are not associated with thoracic aortic dissection, thoracic aortic aneurysm and coronary heart disease.

Time-dependent changes of plasma inflammatory biomarkers in type A aortic dissection patients without optimal medical management

Objectives

To investigate the time-dependent changes in plasma levels of interleukin-6, C-reactive protein, and tumor necrosis factor-α in patients with type A aortic dissection (TAAD) who received unoptimal medical management since the onset of dissections.

Design and methods

Plasma levels of interleukin-6, C-reactive protein, and tumor necrosis factor-α were detected by ELISA and immuno-turbidimetric assay in 92 TAAD patients at hospital admission. Blood samples from 78 patients with uncontrolled hypertension and 82 healthy volunteers were also analyzed as controls. The occurrence of TAAD-related complication and its relationship with the plasma levels of these inflammatory biomarkers was also investigated.

Results

The concentrations of inflammatory mediators were significant higher in TAAD than those in the uncontrolled hypertension and the healthy group. The time to peak plasma level of IL-6.and TNF-α was shorter than that of CRP in TAAD group. In the TAAD group, 51 patients suffered TAAD-related complications, and their plasma level of CRP was significantly higher than that in patients without TAAD-related complications (94.5 ± 58.8 mg/L versus 47.4 ± 47.8 mg/L, p < 0.001). Also, CRP levels strongly correlated with the value of PaO₂/FiO₂ ratio (r = −0.69, p < 0.001) and creatinine (r = 0.60, p < 0.001). The time to the peak level of CRP was shorter and the duration of persistently high CRP level was longer in the complication group than those in the complication-free group.

Conclusions

Elevated and persistently high levels of plasma CRP, IL-6 and TNF-α were associated with progressively development of the TAAD. The changing pattern of CRP might be a marker for diagnosis and prophylactic treatment of complications. Our findings suggested a critical role of the inflammation in the progression of dissection and TAAD-related complications.