Molecular imaging targets of cardiac remodeling

Association of Long Noncoding RNA Expression Signatures with Stress-Induced Myocardial Perfusion Defects

Stress-induced myocardial perfusion defects found in dipyridamole-thallium-201 single-photon emission computed tomography imaging may indicate vascular perfusion abnormalities and risk of obstructive or nonobstructive coronary heart disease. Besides nuclear imaging and subsequent coronary angiography (CAG), no blood test can indicate whether dysregulated homeostasis is associated with stress-induced myocardial perfusion defects. This study investigated the expression signature of long noncoding RNAs (lncRNAs) and genes involved in vascular inflammation and stress response in the blood of patients with stress-induced myocardial perfusion abnormalities (n = 27). The results revealed an expression signature consisting of the upregulation of RMRP (p < 0.01) and downregulations of THRIL (p < 0.01) and HIF1A (p < 0.01) among patients with a positive thallium stress test and no significant coronary artery stenosis within 6 months after baseline treatment. We developed a scoring system based on the expression signatures of RMRP, MIAT, NTT, MALAT1, HSPA1A, and NLRP3 to predict the need for further CAG among patients with moderate-to-significant stress-induced myocardial perfusion defects (area under the receiver operating characteristic curve = 0.963). Therefore, we identified a dysregulated expression profile of lncRNA-based genes in the blood that could be valuable for the early detection of vascular homeostasis imbalance and personalized therapy.

Astragaloside IV inhibits ventricular remodeling and improves fatty acid utilization in rats with chronic heart failure

Chronic heart failure (CHF) is the end-stage of many cardiovascular diseases and severely affects the patients’ lifespan. Inhibiting ventricular remodeling is thus a primary treatment target for CHF patients. Astragaloside IV (AS-IV) can improve cardiac function and protect myocardial cells. The study aims to investigate the effects of AS-IV on ventricular remodeling and explore its role in regulating energy metabolism using a rat CHF model. Sprague–Dawley rats were divided into five groups (n=20 per group): CHF + benazepril hydrochloride (Benazepril HCL), CHF + low-dose (30 mg.kg⁻¹.day⁻¹) AS-IV, CHF + high-dose (60 mg.kg⁻¹.day⁻¹) AS-IV, and a sham control group. After 8 weeks of treatment, the cardiac structure and functional parameters were measured. Morphological changes in the myocardial tissue in five groups were evaluated. Protein and mRNA expression of peroxisome proliferator-activated receptor α (PPARα), medium-chain acyl-CoA dehydrogenase (MCAD), and muscle carnitine palmitoyl transferase-1 (MCPT1) were also analyzed. Our results showed that the left ventricular mass index (LVMI), collagen volume fraction (CVF), and free fatty acid (FFA) concentration of CHF group rats increased when compared with sham control group, while the protein and mRNA expressions of PPARα, MCAD, and MCPT1 decreased in CHF. Importantly, treatment with AS-IV (CHF + AS-IV group) showed improved heart function and structure, increased expression of PPARα, MCAD, and MCPT1 and improved FFA utilization in comparison with CHF group. In conclusion, our study shows that AS-IV inhibits ventricular remodeling, improves cardiac function, and decreases FFA concentration of CHF model rats. Our findings suggest a therapeutic potential of using AS-IV in CHF.

Cardiac molecular imaging to track left ventricular remodeling in heart failure

Cardiac left ventricular (LV) remodeling is the final common pathway of most primary cardiovascular diseases that manifest clinically as heart failure (HF). The more advanced the systolic HF and LV dysfunction, the worse the prognosis. The knowledge of the molecular, cellular, and neurohormonal mechanisms that lead to myocardial dysfunction and symptomatic HF has expanded rapidly and has allowed sophisticated approaches to understanding and management of the disease. New therapeutic targets for pharmacologic intervention in HF have also been identified through discovery of novel cellular and molecular components of membrane-bound receptor-mediated intracellular signal transduction cascades. Despite all advances, however, the prognosis of systolic HF has remained poor in general. This is, at least in part, related to the (1) relatively late institution of treatment due to reliance on gross functional and structural abnormalities that define the "heart failure phenotype" clinically; (2) remarkable genetic-based interindividual variations in the contribution of each of the many molecular components of cardiac remodeling; and (3) inability to monitor the activity of individual pathways to cardiac remodeling in order to estimate the potential benefits of pharmacologic agents, monitor the need for dose titration, and minimize side effects. Imaging of the recognized ultrastructural components of cardiac remodeling can allow redefinition of heart failure based on its "molecular phenotype," and provide a guide to implementation of "personalized" and "evidence-based" evaluation, treatment, and longitudinal monitoring of the disease beyond what is currently available through randomized controlled clinical trials.