Aortic sclerosis, aortic stenosis and lipid-lowering therapy

Tumour necrosis factor-alpha serum level is an independent predictor of medium-term all-cause mortality after transcatheter aortic valve replacement

BACKGROUND

Transcatheter aortic valve implantation (TAVI) is a suitable treatment for patients with severe aortic stenosis and severely increased operative risk. There is need for a better preoperative risk assessment for TAVI candidates.

AIM

To determine whether Tumour necrosis factor-alfa (TNFα) is an independent predictor of survival 500 days after TAVI.

METHODS

Sixty patients undergoing TAVI were enrolled in the study. TNFα was determined. The CT measured low-density muscle fraction (LDM%) of the psoas muscle was determined. Operative risk assessment by Logistic EuroSCORE, EuroSCORE II, and STS score was performed. Frailty scores (FRAIL scale and Barthel index) were determined.

RESULTS

Mean age was 81.01 ± 7.54 years. Twenty-six (43.3%) of the patients were males. In the univariable analyses, FRAIL scale and Barthel index were no predictors of survival after TAVI. In the multivariable analysis, including EuroSCORE II, LDM% and TNFα serum concentration, TNFα serum level was an independent predictor of survival 500 days after TAVI (HR: 3.167; 95%: 1.279-7.842; p = 0.013). The multivariable analysis, including TNFα as a categorical variable, showed that compared to patients in the conjugated first and second TNFα serum level tertile, patients in the third tertile had a hazard ratio (HR) of 10.606 (95%CI: 1.203 - 93.467) (p = 0.033).

CONCLUSION

TNFα is an incremental independent predictor of long-term survival after TAVI.

Spontaneous Degenerative Aortic Valve Disease in New Zealand Obese Mice

Background Degenerative aortic valve (AoV) disease and resulting aortic stenosis are major clinical health problems. Murine models of valve disease are rare, resulting in a translational knowledge gap on underlying mechanisms, functional consequences, and potential therapies. Naïve New Zealand obese (NZO) mice were recently found to have a dramatic decline of left ventricular (LV) function at early age. Therefore, we aimed to identify the underlying cause of reduced LV function in NZO mice. Methods and Results Cardiac function and pulmonary hemodynamics of NZO and age-matched C57BL/6J mice were monitored by serial echocardiographic examinations. AoVs in NZO mice demonstrated extensive thickening, asymmetric aortic leaflet formation, and cartilaginous transformation of the valvular stroma. Doppler echocardiography of the aorta revealed increased peak velocity profiles, holodiastolic flow reversal, and dilatation of the ascending aorta, consistent with aortic stenosis and regurgitation. Compensated LV hypertrophy deteriorated to decompensated LV failure and remodeling, as indicated by increased LV mass, interstitial fibrosis, and inflammatory cell infiltration. Elevated LV pressures in NZO mice were associated with lung congestion and cor pulmonale, evident as right ventricular dilatation, decreased right ventricular function, and increased mean right ventricular systolic pressure, indicative for the development of pulmonary hypertension and ultimately right ventricular failure. Conclusions NZO mice demonstrate as a novel murine model to spontaneously develop degenerative AoV disease, aortic stenosis, and the associated end organ damages of both ventricles and the lung. Closely mimicking the clinical scenario of degenerative AoV disease, the model may facilitate a better mechanistic understanding and testing of novel treatment strategies in degenerative AoV disease.

Andrographolide ameliorates aortic valve calcification by regulation of lipid biosynthesis and glycerolipid metabolism targeting MGLL expression in vitro and in vivo

Calcific aortic valve disease (CAVD) is caused by the initiation of the thickening and calcification of valve leaflets by valve interstitial cells (VICs). Cell metabolic changes during the CAVD process are a new field of basic research on this disease. The present study aimed to investigate whether andrographolide (AGP) could attenuate the calcification of aortic valves by regulating cell metabolism. Gas chromatography-mass spectroscopy (GC-MS) metabolome analysis was utilized to investigate the changes in the metabolites of VICs from healthy and CAVD samples. Cell growth and the osteogenic differentiation of human VICs (hVICs) were assessed using a CCK8 assay and Alizarin Red S staining, respectively. The expression of two calcification-related markers, RUNX2 and ALP, was analyzed by quantitative real-time polymerase chain reaction (qRT-PCR) and immunofluorescence staining. Molecular docking was used to detect the interaction between AGP and monoglyceride lipase (MGLL). The high-fat-fed ApoE-/- mice aortic valve calcification animal model was used to verify the effect of AGP on CAVD in vivo. Metabolome analysis showed that the metabolites of VICs from healthy and CAVD samples were highly enriched in the biosynthesis of unsaturated fatty acids and glycerolipid metabolism. The top six highlighted metabolites were selected to reveal a high regulation of lipids in VICs from CAVD. AGP significantly suppressed the calcific differentiation of VICs while it decreased the accumulation of the above six metabolites, 1-monopalmitic, palmitic acid, glycerol, l-asparagine, tetraethylene glycol, and stearic acid induced by osteogenic medium (OM) stimulation. These metabolites were highly correlated with the calcific marker ALP and showed a positive correlation with CAVD. In the comprehensive assessment, MGLL, associated with glycerol synthesis, was selected as the molecular target of AGP in inhibiting the calcific phenotype of transforming hVICs. The in vivo results revealed that AGP visibly ameliorated aortic valve calcification by reducing Von Kossa and ALP staining, which was positively correlated with MGLL expression. AGP ameliorated aortic valve calcification by regulating lipid biosynthesis and glycerolipid metabolism targeting MGLL expression in vitro and in vivo. It is a potent therapeutic supplement that prevents the occurrence of heart valve calcification disease by regulating cell metabolism.

Role of oxidative stress in calcific aortic valve disease and its therapeutic implications

Calcific aortic valve disease (CAVD) is the end result of active cellular processes that lead to the progressive fibrosis and calcification of aortic valve leaflets. In western populations, CAVD is a significant cause of cardiovascular morbidity and mortality, and in the absence of effective drugs, it will likely represent an increasing disease burden as populations age. As there are currently no pharmacological therapies available for preventing, treating, or slowing the development of CAVD, understanding the mechanisms underlying the initiation and progression of the disease is important for identifying novel therapeutic targets. Recent evidence has emerged of an important causative role for reactive oxygen species (ROS)-mediated oxidative stress in the pathophysiology of CAVD, inducing the differentiation of valve interstitial cells into myofibroblasts and then osteoblasts. In this review, we focus on the roles and sources of ROS driving CAVD and consider their potential as novel therapeutic targets for this debilitating condition.

Degenerative Aortic Stenosis, Dyslipidemia and Possibilities of Medical Treatment

Degenerative aortic stenosis (DAS) is the most frequently diagnosed heart valve disease in Europe and North America. DAS is a chronic progressive disease which resembles development of atherosclerosis. Endothelial dysfunction, lipid infiltration, calcification and ossification are evidenced in both diseases. The same risk factors such as older age, male sex, smoking, and elevated levels of lipids are identified. The effect of smoking, visceral obesity, metabolic syndrome, hypercholesterolemia, low-density lipoprotein, high-density lipoprotein, lipoprotein(a), adiponectin and apolipoprotein(a) on development of DAS are being studied. The search for genetic ties between disorders of lipid metabolism and DAS has been started. DAS is characterized by a long symptom-free period which can last for several decades. Aortic valve replacement surgery is necessary when the symptoms occur. The lipid-lowering therapy effect on stopping or at least slowing down the progression of DAS was studied. However, the results of the conducted clinical trials are controversial. In addition, calcium homeostasis, bone metabolism and calcinosis-reducing medication are being studied. Although prospective randomized clinical trials have not demonstrated any positive effect of statins used for slowing progression of the disease, statins are still recommended for patients with dyslipidemia. Recent study has suggested that a specific modification of treatment, based on severity of disease, may have a beneficial effect in patients with aortic sclerosis and mild DAS. New clinical studies analyzing new treatment possibilities which could correct the natural course of the disease and reduce the need for aortic valve replacement by surgery or transcatheter treatment interventions are needed.

Is there evidence for statins in the treatment of aortic valve stenosis?

Research revealed that the pathogenesis of aortic stenosis (AS) not merely comprises of a mechanical wear and tear process yet that active biological processes, similar to those of coronary artery disease are involved, a promising role for statins in disease-modifying therapy was suggested. However, recently, many prospective studies could not observe decreased progression nor regression of the disease. Here, we review the current knowledge on the pathomechanisms of AS and its similarities and differences with atherosclerosis. Moreover, we discuss whether there is still a place for statins in the treatment of particular AS patient subgroups.

Molecular and cellular aspects of calcific aortic valve disease

Calcific aortic valve disease (CAVD) increasingly afflicts our aging population. One third of our elderly have echocardiographic or radiological evidence of calcific aortic valve sclerosis, an early and subclinical form of CAVD. Age, sex, tobacco use, hypercholesterolemia, hypertension, and type II diabetes mellitus all contribute to the risk of disease that has worldwide distribution. On progression to its most severe form, calcific aortic stenosis, CAVD becomes debilitating and devastating, and 2% of individuals >60 years are affected by calcific aortic stenosis to the extent that surgical intervention is required. No effective pharmacotherapies exist for treating those at risk for clinical progression. It is becoming increasingly apparent that a diverse spectrum of cellular and molecular mechanisms converge to regulate valvular calcium load; this is evidenced not only in histopathologic heterogeneity of CAVD, but also from the multiplicity of cell types that can participate in valve biomineralization. In this review, we highlight our current understanding of CAVD disease biology, emphasizing molecular and cellular aspects of its regulation. We end by pointing to important biological and clinical questions that must be answered to enable sophisticated disease staging and the development of new strategies to treat CAVD medically.

Mitigation of diabetes-related complications in implanted collagen and elastin scaffolds using matrix-binding polyphenol

There is a major need for scaffold-based tissue engineered vascular grafts and heart valves with long-term patency and durability to be used in diabetic cardiovascular patients. We hypothesized that diabetes, by virtue of glycoxidation reactions, can directly crosslink implanted scaffolds, drastically altering their properties. In order to investigate the fate of tissue engineered scaffolds in diabetic conditions, we prepared valvular collagen scaffolds and arterial elastin scaffolds by decellularization and implanted them subdermally in diabetic rats. Both types of scaffolds exhibited significant levels of advanced glycation end products (AGEs), chemical crosslinking and stiffening -alterations which are not favorable for cardiovascular tissue engineering. Pre-implantation treatment of collagen and elastin scaffolds with penta-galloyl glucose (PGG), an antioxidant and matrix-binding polyphenol, chemically stabilized the scaffolds, reduced their enzymatic degradation, and protected them from diabetes-related complications by reduction of scaffold-bound AGE levels. PGG-treated scaffolds resisted diabetes-induced crosslinking and stiffening, were protected from calcification, and exhibited controlled remodeling in vivo, thereby supporting future use of diabetes-resistant scaffolds for cardiovascular tissue engineering in patients with diabetes.

Sex-related differences in gene expression by porcine aortic valvular interstitial cells

While many large-scale risk factors for calcific aortic valve disease (CAVD) have been identified, the molecular etiology and subsequent pathogenesis of CAVD have yet to be fully understood. Specifically, it is unclear what biological phenomena underlie the significantly higher occurrence of CAVD in the male population. We hypothesized the existence of intrinsic, cellular-scale differences between male and female valvular interstitial cells (VICs) that contribute to male sex being a risk factor for CAVD. Differences in gene expression profiles between healthy male and female porcine VICs were investigated via microarray analysis. Mean expression values of each probe set in the male samples were compared to the female samples, and biological processes were analyzed for overrepresentation using Gene Ontology term enrichment analysis. There were 183 genes identified as significantly (fold change>2; P<0.05) different in male versus female aortic valve leaflets. Within this significant gene list there were 298 overrepresented biological processes, several of which are relevant to pathways identified in CAVD pathogenesis. In particular, pathway analysis indicated that cellular proliferation, apoptosis, migration, ossification, angiogenesis, inflammation, and extracellular matrix reorganization were all significantly represented in the data set. These gene expression findings also translated into functional differences in VIC behavior in the in vitro environment, as sex-related differences in proliferation and apoptosis were confirmed in VIC populations cultured in vitro. These data suggest that a sex-related propensity for CAVD exists on the cellular level in healthy subjects, a phenomenon that could have significant clinical implications. These findings also strongly support discontinuing the use of mixed-sex VIC cultures, thereby changing the current standard in the field.

The roles of lipid oxidation products and receptor activator of nuclear factor-κB signaling in atherosclerotic calcification

This review focuses on the roles of oxylipids and receptor activator of nuclear factor-κB ligand signaling in calcific cardiovascular disease. Both intimal and valvular calcifications are closely associated with atherosclerosis, leading investigators to study the role of atherogenic oxidatively modified lipids (oxylipids). Results have identified the molecular signaling through which oxylipids induce osteogenic differentiation and calcification in vascular cells. A surprising concomitant finding was that, in bona fide osteoblasts from skeletal bone, oxylipids have the opposite effect, ie, inhibiting osteoblastic maturation. This is the basis for the lipid hypothesis of osteoporosis. Oxylipids also induce resorptive osteoclastic cells within the bone environment, raising the question of whether resorptive osteoclasts can be harnessed in the vascular context for cell-based therapy to remove artery wall mineral deposits. The challenge is that vascular cells produce antiosteoclastogenic factors, including the soluble decoy receptor for receptor activator of nuclear factor-κB ligand, possibly accounting for the paucity of resorptive cells and the dominance of mineral in atherosclerotic plaque. These factors may have therapeutic use in osteoclastogenic removal of mineral deposits from arteries.

Aortic stenosis and lipids: does intervention work?

PURPOSE OF REVIEW

Aortic stenosis is a common disorder affecting increasing numbers of elderly patients, which is associated with markedly increased cardiovascular morbidity and mortality. Both histological and epidemiological studies have suggested that the process of valve degeneration may resemble atherosclerosis. This review investigates the potential role of lipid-lowering therapy in its management.

RECENT FINDINGS

The current treatment methods are surgical or endovascular intervention but it has been hoped that antiatherosclerotic therapies might result in a reduction in progression and need for intervention. There have been a number of retrospective studies of lipid-lowering therapy, which suggested that statins might be effective in reducing progression of aortic stenosis. Lately a series of trials of aggressive statin therapy on surrogate markers of progression have shown no benefit from these measures. The controversial Simvastatin-Ezetimibe and Aortic Stenosis (SEAS) endpoint trial did not show any benefit on a combined endpoint of valve-related and ischaemic events but hinted at a reduction in cardiovascular events in this high cardiovascular risk group.

SUMMARY

The data clearly shows statins have little effect in well established stenotic disease with calcification, but their effects earlier in the disease process (aortic valve sclerosis) remain to be determined.

Undercarboxylated matrix Gla protein is associated with indices of heart failure and mortality in symptomatic aortic stenosis

OBJECTIVE

Matrix Gla protein (MGP) is a calcification inhibitor and alterations in circulating MGP have been observed in different populations characterized by vascular calcification. We hypothesized that patients with calcific valvular aortic stenosis (AS) would have dysregulated circulating MGP levels.

DESIGN AND SUBJECTS

We examined plasma levels of nonphosphorylated carboxylated and undercarboxylated MGP (dp-cMGP and dp-ucMGP, respectively) in 147 patients with symptomatic severe AS and in matched healthy controls.

MAIN OUTCOME MEASURES

We further investigated the relationship between MGP levels and aortic pressure gradients and valve area by echocardiography and measures of heart failure. Finally, we assessed the prognostic value of elevated plasma dp-ucMGP level in relation to all-cause mortality in patients with AS.

RESULTS

We found markedly enhanced plasma levels of dp-cMGP and in particular of dp-ucMGP in patients with symptomatic AS. Although only weak correlations were found with the degree of AS, circulating dp-ucMGP was associated with cardiac function and long-term mortality in multivariate analysis.

CONCLUSIONS

A dysregulated MGP system may have a role in the development of left ventricular dysfunction in patients with symptomatic AS.

Statins and cancer: a potential link?

Hypercholesterolemia is a growing health concern in the United States. Pharmacotherapy is increasingly being used to combat the long-term consequences of elevated cholesterol levels. One of the primary pharmacological treatments for hypercholesterolemia is a class of lipid lowering drugs collectively referred to as statins. After introduction of the first statin in 1987, their use quickly became the norm. Recent release of the results from the Simvastatin and Ezetimibe in Aortic Stenosis (SEAS) study unveiled a potential increased risk of cancer and cancer death for individuals taking the well-known drug combination of ezetimibe/simvastatin. Our aim with this review is to look at previous studies to see if any other studies have shown a similar correlation between statins or other lipid-lowering drugs and cancer. The associated studies gathered are reviews, randomized, controlled trials, editorials, and commentaries. We obtained these studies by using electronic searches such as PubMed, Medline, and Cochrane Library. Searches were limited in that certain keywords took precedence, and articles mainly focusing on statins and ezetimibe as opposed to other lipid-lowering drugs were chosen. We have shown that aside from the SEAS study, there are numerous other studies that have also found potential links between statins and various forms of cancer. However, there is also an abundance of literature showing the contrary. Currently, scientific data are slightly in favor of the notion that statins do not cause a significant increase in cancer rates. However, there are many studies that show small correlations between statin use and increased incidence of cancer and therefore, we feel further prospective studies are needed. Whether statins do cause cancer remains uncertain at this point in time.