Bicuspid aortic valve, atherosclerosis and changes of lipid metabolism: Are there pathological molecular links?

Dyslipidemia in adults with congenital heart disease: A systematic review and meta-analysis

AIMS

Several particular characteristics of patients with congenital heart disease could affect lipid levels. The objectives of this study were: a) to analyze the prevalence of dyslipidemia in congenital heart disease patients; 2) to compare lipid levels between congenital heart disease patients and a control group.

DATA SYNTHESIS

This systematic review and meta-analysis was performed according to PRISMA guidelines (PROSPERO CRD42023432041). A literature search was performed to detect studies that have reported lipid levels or the prevalence of dyslipidemia in congenital heart disease patients. We performed a qualitative analysis (studies that reported dyslipidemia prevalence) and quantitative analysis (studies that compared lipid values between congenital heart disease patients and controls). In total, 29 observational studies involving 22,914 patients with congenital heart disease and 641,086 controls were eligible for this review. The reported presence of "hyperlipidemia" or "dyslipidemia" ranged from 14.3% to 69.9%. When studies analyzed lipid variables dichotomously between congenital heart disease patients and controls, the results were conflicting. The quantitative analysis showed that patients with congenital heart disease have lower levels of total cholesterol (MD: -18.9 [95% CI: -22.2 to -15.7]; I2 = 93%), LDL-C (MD: -10.7 [95% CI: -13.1 to -8.3]; I2 = 90%) and HDL-C (MD: -6.3 [95% CI: -7.7 to -4.9]; I2 = 95%) compared to controls.

CONCLUSIONS

The qualitative analysis showed some concerns, but the quantitative analysis indicates that congenital heart disease patients showed lower levels of total cholesterol, LDL-C, and HDL-C compared to controls. New research should be developed to clarify this relevant topic.

The Prevalence of Coronary Artery Disease in Bicuspid Aortic Valve Patients: An Overview of the Literature

The prevalence of coronary artery disease (CAD) in bicuspid aortic valve (BAV) patients is a debatable topic. Several studies have indicated that BAV patients have a lower prevalence of CAD compared with patients with a tricuspid aortic valve (TAV), but the effects of age and gender have not always been considered. This systematic review provides an overview of articles which report on CAD in BAV and TAV patients. Searches were executed in April 2021 and January 2022 according to the PRISMA (Preferred Reporting Items for Systematic reviews and Meta-analyses) guidelines in three online databases: Medline, Embase, and Scopus. Screening and data extraction was done by two investigators separately. Primary and secondary outcomes were compared between BAV and TAV patients; a fixed effects model was used for correcting on confounders. Literature search yielded 1,529 articles with 44 being eligible for inclusion. BAV patients were younger (56.4 ± 8.3 years) than TAV patients (64 ± 10.3 years, p < 0.001). All CAD risk factors and CAD were more prevalent in TAV patients. No significant difference remained after correcting for age and gender as confounders. BAV patients have a lower prevalence of CAD and CAD risk factors compared with TAV patients. However, when the age differences between both groups are considered in the analyses, a similar prevalence of both CAD and CAD risk factors is found.

Identification of recurrent variants implicated in disease in bicuspid aortic valve patients through whole-exome sequencing

Bicuspid aortic valve (BAV) is the most common congenital heart defect in human beings, with an estimated prevalence in the general population of between 0.5 and 2%. Moreover, BAV is the most common cause of aortic stenosis in the pediatric population. Patients with BAV may have no symptoms for life, and some of them may progress to aortic stenosis. Genetic factors increase the susceptibility and development of BAV. However, the pathogenesis and BAV are still unclear, and more genetic variants are still needed for elucidating the molecular mechanism and stratification of patients. The present study carried out screening of variants implicated in disease in BAV patients. The whole-exome sequencing (WES) was performed in 20 BAV patients and identified 40 different heterozygous missense mutations in 36 genes (MIB2, FAAH, S100A1, RGS16, MAP3K19, NEB, TTN, TNS1, CAND2, CCK, KALRN, ATP10D, SLIT3, ROS1, FABP7, NUP205, IL11RA, NPR2, COL5A1, CUBN, JMJD1C, ANXA7, TRIM8, LGR4, TPCN2, APOA5, GPR84, LRP1, NCOR2, AKAP11, ESRRB, NGB, AKAP13, WWOX, KCNJ12, ARHGEF1). The mutations in these genes were identified as recurrent variants implicated in disease by in silico prediction tool analysis. Nine genes (MIB2, S100A1, TTN, CCK, NUP205, LGR4, NCOR2, ESRRB, and WWOX) among the 36 genes were identified as variants implicated in disease via unanimous agreement of in silico prediction tool analysis and sequenced in an independent cohort of 137 BAV patients to validate the results of WES. BAV patients carrying these variants demonstrated reduced left ventricular ejection fractions (LVEF) (63.8 ± 7.5% vs. 58.4 ± 5.2%, P < 0.001) and larger calcification volume [(1129.3 ± 154) mm³ vs. (1261.8 ± 123) mm³, P < 0.001]. The variants in TTN, NUP205 and NCOR2 genes are significantly associated with reduced LVEF, and the variants in S100A1, LGR4, ESRRB, and WWOX genes are significantly associated with larger calcification volume. We identified a panel of recurrent variants implicated in disease in genes related to the pathogenesis of BAV. Our data speculate that these variants are promising markers for risk stratification of BAV patients with increased susceptibility to aortic stenosis.

Propamocarb exposure has the potential to accelerate the formation of atherosclerosis in both WT and ApoE-/- mice accompanied by gut microbiota dysbiosis

Propamocarb is a systemic carbamate fungicide used to fight diseases. The effect of propamocarb on the formation of atherosclerosis was evaluated in wild-type (WT) and ApoE knockout (ApoE^-/-) mice. C57BL/6 J WT mice were fed control diet or high-fat diet (HFD) with 20 mg/L propamocarb in drinking water for 24 weeks. Propamocarb significantly increased the serum levels of triglyceride, cholesterol and low-density lipoprotein cholesterol while decreasing high-density lipoprotein cholesterol. Simultaneously, propamocarb facilitated lipid accumulation in the liver and increased the expression of cholesterol synthesis and transport genes in the liver and ileum. Lipid accumulation was observed in the aortic roots of the propamocarb-treated mice fed HFD, and similar results were also observed with whole aorta staining. In addition, propamocarb exposure significantly increased the mRNA levels of IL-1β, TNF-α, ICAM-1, and VCAM-1 in the aorta and the serum IL-1β, IL-6, and TNF-α levels in HFD groups treated with propamocarb. In ApoE^-/- mice, the results were consistent with those obtained in WT mice after exposure to 20 mg/L propamocarb for 10 weeks. Meanwhile, propamocarb significantly increased the levels of CD36, NF-κB, VCAM-1 and ICAM-1 proteins in the aortas of ApoE^-/- mice. Propamocarb further disrupted cholesterol metabolism and enhanced atherosclerosis and inflammatory responses much more substantially, indicating that propamocarb has the potential to accelerate the formation of atherosclerosis. An analysis of gut microbiota revealed that propamocarb altered the composition of gut microbiota in both WT and ApoE^-/- mice. Interestingly, propamocarb increased the abundance of Peptostreptococcaceae, Ruminococcaceae, and Clostridiales_VadinBB60_group, which are related to atherosclerosis at the family level. The abundance of Paeniclostridium, Allobaculum, and Clostridioides, which are closely related to atherosclerosis, was also increased by propamocarb exposure. Our findings indicate that propamocarb exposure may promote atherosclerosis by disrupting lipid metabolism, increasing the inflammatory response, and altering the structure of gut microbiota.

Extent of Coronary Artery Disease in Patients With Stenotic Bicuspid Versus Tricuspid Aortic Valves

Background Bicuspid aortic valve (BAV) is the most common congenital cardiac malformation, which is often complicated by aortic valve stenosis (AoS). In tricuspid aortic valve (TAV), AoS strongly associates with coronary artery disease (CAD) with common pathophysiological factors. Yet, it remains unclear whether AoS in patients with BAV is also associated with CAD. This study investigated the association between the aortic valve morphological features and the extent of CAD. Methods and Results A single-center study was performed, including all patients who underwent an aortic valve replacement attributable to AoS between 2006 and 2019. Coronary sclerosis was graded on preoperative coronary angiographies using the coronary artery greater even than scoring method, which divides the coronaries in 28 segments and scores nonobstructive (20%-49% sclerosis) and obstructive coronary sclerosis (>49% sclerosis) in each segment. Multivariate analyses were performed, controlling for age, sex, and CAD risk factors. A total of 1296 patients (931 TAV and 365 BAV) were included, resulting in 548 matched patients. Patients with TAV exhibited more CAD risk factors (odds ratio [OR], 2.66; 95% CI, 1.79-3.96; P<0.001). Patients with BAV had lower coronary artery greater even than 20 (1.61±2.35 versus 3.60±2.79) and coronary artery greater even than 50 (1.24±2.43 versus 3.37±3.49) scores (P<0.001), even after correcting for CAD risk factors (P<0.001). Patients with TAV more often needed concomitant coronary revascularization (OR, 3.50; 95% CI, 2.42-5.06; P<0.001). Conclusions Patients with BAV who are undergoing surgery for AoS carry a lower cardiovascular risk profile, correlating with less coronary sclerosis and a lower incidence of concomitant coronary revascularization compared with patients with TAV.

The Chromatin Remodeling Protein BRG1 Regulates SREBP Maturation by Activating SCAP Transcription in Hepatocytes

Sterol response element binding protein (SREBP) is a master regulator of cellular lipogenesis. One key step in the regulation of SREBP activity is its sequential cleavage and trans-location by several different proteinases including SREBP cleavage activating protein (SCAP). We have previously reported that Brahma related gene 1 (BRG1) directly interacts with SREBP1c and SREBP2 to activate pro-lipogenic transcription in hepatocytes. We report here that BRG1 deficiency resulted in reduced processing and nuclear accumulation of SREBP in the murine livers in two different models of non-alcoholic steatohepatitis (NASH). Exposure of hepatocytes to lipopolysaccharide (LPS) and palmitate (PA) promoted SREBP accumulation in the nucleus whereas BRG1 knockdown or inhibition blocked SREBP maturation. Further analysis revealed that BRG1 played an essential role in the regulation of SCAP expression. Mechanistically, BRG1 interacted with Sp1 and directly bound to the SCAP promoter to activate SCAP transcription. Forced expression of exogenous SCAP partially rescued the deficiency in the expression of SREBP target genes in BRG1-null hepatocytes. In conclusion, our data uncover a novel mechanism by which BRG1 contributes to SREBP-dependent lipid metabolism.

Plasma Metabolomic Profiling Associates Bicuspid Aortic Valve Disease and Ascending Aortic Dilation with a Decrease in Antioxidant Capacity

BACKGROUND

The bicuspid aortic valve (BAV) is the most common cardiac congenital disease and is associated with an increased risk of developing ascending aorta dilation; which can have fatal consequences. Currently; no established risk biomarkers exist to facilitate the diagnosis and prognosis of BAV.

METHODS

Using an untargeted metabolomic approach; we identified the levels of metabolites in plasma samples and compared them depending on the bicuspid or tricuspid morphology of the aortic valve. Including those patients with ascending aortic dilation and/or aortic stenosis (n = 212), we analyzed the role possibly played by alpha-Tocopherol in BAV disease; considering its association with the pathophysiological characteristics of BAV and biomarkers related to inflammation, oxidative stress and endothelial damage, as well as characteristics related to alpha-Tocopherol functionality and metabolism.

RESULTS

We found that BAV patients; especially those with ascending aortic dilation; presented lower antioxidant capacity; as determined by decreased plasma levels of alpha-Tocopherol; paraoxonase 1 and high-density lipoprotein (HDL), as well as increased levels of C-reactive protein (CRP; a biomarker of inflammation) and endothelial microparticles (EMPs; an endothelial damage biomarker). By applying random forest analyses; we evaluated the significant screening capacity of alpha-Tocopherol; CRP and EMPs to classify patients depending on the morphology of the aortic valve.

DISCUSSION

Our findings support the role of decreased antioxidant capacity; increased inflammation and endothelial damage in the pathogenesis of BAV and the progression of aortic dilation. Moreover; determining the plasma levels of alpha-Tocopherol; CRP and EMPs could improve BAV diagnosis in large populations.

An Exploratory Look at Bicuspid Aortic Valve (Bav) Aortopathy: Focus on Molecular and Cellular Mechanisms

Bicuspid aortic valve (BAV) is the most common congenital heart malformation. BAV patients are at increased risk for aortic valve disease (stenosis/regurgitation), infective endocarditis, thrombi formation and, in particular, aortic dilatation, aneurysm and dissection. This review aims at exploring the possible interplay among genetics, extracellular matrix remodeling, abnormal signaling pathways, oxidative stress and inflammation in contributing to BAV-associated aortopathy (BAV-A-A). Novel circulating biomarkers have been proposed as diagnostic tools able to improve risk stratification in BAV-A-A. However, to date, the precise molecular and cellular mechanisms that lead to BAV-A-A remain unknown. Genetic, hemodynamic and cardiovascular risk factors have been implicated in the development and progression of BAV-A-A. Oxidative stress may also play a role, similarly to what observed in atherosclerosis and vulnerable plaque formation. The identification of common pathways between these 2 conditions may provide a platform for future therapeutic solutions.