Short-term LPS induces aortic valve thickening in ApoE*3Leiden mice

Albumin Thiolation and Oxidative Stress Status in Patients with Aortic Valve Stenosis

Recent evidence indicates that reactive oxygen species play an important causative role in the onset and progression of valvular diseases. Here, we analyzed the oxidative modifications of albumin (HSA) occurring on Cysteine 34 and the antioxidant capacity of the serum in 44 patients with severe aortic stenosis (36 patients underwent aortic valve replacement and 8 underwent a second aortic valve substitution due to a degenerated bioprosthetic valve), and in 10 healthy donors (controls). Before surgical intervention, patients showed an increase in the oxidized form of albumin (HSA-Cys), a decrease in the native reduced form (HSA-SH), and a significant reduction in serum free sulfhydryl groups and in the total serum antioxidant activity. Patients undergoing a second valve replacement showed levels of HSA-Cys, free sulfhydryl groups, and total antioxidant activity similar to those of controls. In vitro incubation of whole blood with aspirin (ASA) significantly increased the free sulfhydryl groups, suggesting that the in vivo treatment with ASA may contribute to reducing oxidative stress. We also found that N-acetylcysteine and its amide derivative were able to regenerate HSA-SH. In conclusion, the systemic oxidative stress reflected by high levels of HSA-Cys is increased in patients with aortic valve stenosis. Thiol-disulfide breaking agents regenerate HSA-SH, thus paving the way to the use these compounds to mitigate the oxidative stress occurring in the disease.

Mechanical injury accentuates lipid deposition in ApoE-/- mice and advance aortic valve stenosis: A novel modified aortic valve stenosis model

Background

Current mouse models still have limitations in studying aortic valve stenosis (AVS). A suitable animal model bearing a close resemblance to the pathophysiological processes of humans needs to be developed. Here, we combined two risk factors to create a mouse model that mimics the pathological features of human AVS.

Methods and results

We combined WI and hyperlipidemia in ApoE^-/- mice to explore the synergistic effect on the stenosis of the aortic valve. Transthoracic echocardiography revealed progressively increased peak velocity with age in ApoE^-/- mice to velocities above C57 mice when fed a high-fat diet after wire injury. Moreover, ApoE^-/- mice demonstrated lower cusp separation and lower aortic valve area after 8 weeks vs. C57 mice. Gross morphology and MRI showed advanced thickening, sclerosis aortic valve, narrowing of the orifice area, and micro-CT showed obvious calcification in the aortic valves in the hyperlipidemia group after wire injury. Histopathology studies showed thickening and fibrosis of aortic valve leaflets in the hyperlipidemia group after wire injury. Notably, lipid deposition was observed in ApoE^-/- mice 8 weeks after wire injury, accompanied by overexpressed apoB and apoA proteins. After wire injury, the hyperlipidemia group exhibited augmented inflammation, ROS production, and apoptosis in the leaflets. Moreover, the combination group exhibited advanced fibro-calcific aortic valves after wire injury.

Conclusion

Overall, we present the synergistic effect of wire injury and hyperlipidemia on lipoproteins deposition in the development of AVS in ApoE^-/- mice, this model bear close resemblance to human AVS pathology.

The tyrosine kinase inhibitor nilotinib targets discoidin domain receptor 2 in calcific aortic valve stenosis

Background and Purpose

Tyrosine kinase inhibitors (TKI) used to treat chronic myeloid leukaemia (CML) have been associated with cardiovascular side effects, including reports of calcific aortic valve stenosis. The aim of this study was to establish the effects of first and second generation TKIs in aortic valve stenosis and to determine the associated molecular mechanisms.

Experimental Approach

Hyperlipidemic APOE*3Leiden.CETP transgenic mice were treated with nilotinib, imatinib or vehicle. Human valvular interstitial cells (VICs) were isolated and studied in vitro. Gene expression analysis was perfromed in aortic valves from 64 patients undergoing aortic valve replacement surgery.

Key Results

Nilotinib increased murine aortic valve thickness. Nilotinib, but not imatinib, promoted calcification and osteogenic activation and decreased autophagy in human VICs. Differential tyrosine kinase expression was detected between healthy and calcified valve tissue. Transcriptomic target identification revealed that the discoidin domain receptor DDR2, which is preferentially inhibited by nilotinib, was predominantly expressed in human aortic valves but markedly downregulated in calcified valve tissue. Nilotinib and selective DDR2 targeting in VICs induced a similar osteogenic activation, which was blunted by increasing the DDR2 ligand, collagen.

Conclusions and Implications

These findings suggest that inhibition of DDR2 by nilotinib promoted aortic valve thickening and VIC calcification, with possible translational implications for cardiovascular surveillance and possible personalized medicine in CML patients.

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.

Toward the Effective Bioengineering of a Pathological Tissue for Cardiovascular Disease Modeling: Old Strategies and New Frontiers for Prevention, Diagnosis, and Therapy

Cardiovascular diseases (CVDs) still represent the primary cause of mortality worldwide. Preclinical modeling by recapitulating human pathophysiology is fundamental to advance the comprehension of these diseases and propose effective strategies for their prevention, diagnosis, and treatment. In silico, in vivo, and in vitro models have been applied to dissect many cardiovascular pathologies. Computational and bioinformatic simulations allow developing algorithmic disease models considering all known variables and severity degrees of disease. In vivo studies based on small or large animals have a long tradition and largely contribute to the current treatment and management of CVDs. In vitro investigation with two-dimensional cell culture demonstrates its suitability to analyze the behavior of single, diseased cellular types. The introduction of induced pluripotent stem cell technology and the application of bioengineering principles raised the bar toward in vitro three-dimensional modeling by enabling the development of pathological tissue equivalents. This review article intends to describe the advantages and disadvantages of past and present modeling approaches applied to provide insights on some of the most relevant congenital and acquired CVDs, such as rhythm disturbances, bicuspid aortic valve, cardiac infections and autoimmunity, cardiovascular fibrosis, atherosclerosis, and calcific aortic valve stenosis.

Resveratrol ameliorates atherosclerosis induced by high-fat diet and LPS in ApoE-/- mice and inhibits the activation of CD4+ T cells

Background

Atherosclerosis (AS), which characterized with the accumulation of lipids on the vessel wall, is the pathological basis of many cardiovascular diseases (CVD) and seriously threatens human health. Resveratrol (RES) has been reported to be benefit for AS treatment. This research aimed to observe the effects of RES on AS induced by high-fat diet (HFD) and LPS in ApoE^-/- mice and investigate the underlying mechanism.

Methods

ApoE^-/- mice were fed with HFD companied with LPS to induce AS and RES was administrated for 20 weeks. Splenic CD4⁺ T cells were cultured and treated with anti-CD3/CD28 together with LPS, and RES was added. Serum lipids and the atherosclerotic areas of aortas were detected. The activation of CD4⁺ T cells were investigated both in vivo and in vitro and the expression of DNA methyltransferases (Dnmt) in CD4⁺ T cells were measured.

Results

In vivo, administration of RES prevented HFD and LPS induced dysfunction of serum lipids including TC (total cholesterol), TG (triglyceride), LDL-C (low density lipoprotein cholesterol) and HDL-C (high density lipoprotein cholesterol), ameliorated the thickened coronary artery wall and decreased the areas of atherosclerotic lesion on aortas. Besides, RES decreased the number of CD4⁺ T cells in peripheral blood, decreased the expression of CD25 and CD44, but not affected the expression of L-selectin (CD62L). In vitro, RES decreased the expression of Ki67, CD25 and CD44 in CD4⁺ T cells. Moreover, RES increased the secretion of IL-2, IL-10 and TGF-β1, decreased IL-6. In addition, RES decreased both the mRNA and protein level of Dnmt1 and Dnmt3b in CD4⁺ T cells.

Conclusion

These results indicated that RES ameliorated AS induced by HFD companied with LPS in ApoE^-/- mice, inhibited the proliferation and activation of CD4⁺ T cells and regulated the expression of Dnmt1 and Dnmt3b.