Browsing by keyword "cardiac remodeling"
Now showing items 1-3 of 3
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Micro-RNAs Are Related to Epicardial Adipose Tissue in Participants With Atrial Fibrillation: Data From the MiRhythm StudyIntroduction: Epicardial adipose tissue (EAT) has been linked to incidence and recurrence of atrial fibrillation (AF), but the underlying mechanisms that mediate this association remain unclear. Circulating microRNAs (miRNAs) contribute to the regulation of gene expression in cardiovascular diseases, including AF. Thus, we sought to test the hypothesis that circulating miRNAs relate to burden of EAT. Methods: We examined the plasma miRNA profiles of 91 participants from the miRhythm study, an ongoing study examining associations between miRNA and AF. We quantified plasma expression of 86 unique miRNAs commonly expressed in cardiomyocytes using quantitative reverse transcriptase polymerase chain reaction (qPCR). From computed tomography, we used validated methods to quantify the EAT area surrounding the left atrium (LA) and indexed it to body surface area (BSA) to calculate indexed LA EAT (iLAEAT). Participants were divided into tertiles of iLAEAT to identify associations with unique miRNAs. We performed logistic regression analyses adjusting for factors associated with AF to examine relations between iLAEAT and miRNA. We performed further bioinformatics analysis of miRNA predicted target genes to identify potential molecular pathways are regulated by the miRNAs. Results: The mean age of the participants was 59 +/- 9, 35% were women, and 97% were Caucasian. Participants in the highest tertile of iLAEAT were more likely to have hypertension, heart failure, and thick posterior walls. In regression analyses, we found that miRNAs 155-5p (p < 0.001) and 302a-3p (p < 0.001) were significantly associated with iLAEAT in patients with AF. The predicted targets of the miRNAs identified were implicated in the regulation of cardiac hypertrophy, adipogenesis, interleukin-8 (IL-8), and nerve growth factor (NGF) signaling. Conclusion: miRNA as well as EAT have previously been linked to AF. Our finding that iLAEAT and miRNAs 155-5p and 302a-3p are associated suggest a possible direct link to between these entities in the development and maintenance of AF. Further research is needed to study causal relationships between these biomarkers.
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NLRP3 Inflammasome Promotes Myocardial Remodeling During Diet-Induced ObesityBackground: Obesity is an increasingly prevalent metabolic disorder in the modern world and is associated with structural and functional changes in the heart. The NLRP3 inflammasome is an innate immune sensor that can be activated in response to endogenous danger signals and triggers activation of interleukin (IL)-1beta and IL-18. Increasing evidence points to the involvement of the NLRP3 inflammasome in obesity-induced inflammation and insulin resistance, and we hypothesized that it also could play a role in the development of obesity induced cardiac alterations. Methods and Results: WT, Nlrp3 (-/-), and ASC (-/-) (Pycard (-/-)) male mice were exposed to high fat diet (HFD; 60 cal% fat) or control diet for 52 weeks. Cardiac structure and function were evaluated by echocardiography and magnetic resonance imaging, respectively. Whereas, NLRP3 and ASC deficiency did not affect the cardiac hypertrophic response to obesity, it was preventive against left ventricle concentric remodeling and impairment of diastolic function. Furthermore, whereas NLRP3 and ASC deficiency attenuated systemic inflammation in HFD fed mice; long-term HFD did not induce significant cardiac fibrosis or inflammation, suggesting that the beneficial effects of NLRP3 inflammasome deficiency on myocardial remodeling at least partly reflect systemic mechanisms. Nlrp3 and ASC (Pycard) deficient mice were also protected against obesity-induced systemic metabolic dysregulation, as well as lipid accumulation and impaired insulin signaling in hepatic and cardiac tissues. Conclusions: Our data indicate that the NLRP3 inflammasome modulates cardiac concentric remodeling in obesity through effects on systemic inflammation and metabolic disturbances, with effect on insulin signaling as a potential mediator within the myocardium.
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Transcriptional Regulation of Cardiac Remodeling in a Porcine Model with Validation in Human SubjectsIntroduction: The majority of new atrial fibrillation (AF) cases occur in elderly patients with cardiac remodeling (CR) in the setting of structural heart disease and heart failure (HF). We leveraged a unique animal model to identify cardiac microRNAs (miRNAs) and gene regulatory mechanisms that drive this process. Methods: We prospectively quantified atrial expression of 48 miRNAs by high-throughput qRT-PCR in 15 pigs with right-atrial pacing-induced heart disease (5 pigs with AF/severe HF, 5 pigs with AF/mild HF, and 5 control pigs) as well as in 21 patients (11 with AF and CR and 10 controls) undergoing cardiac surgery. CR and HF were defined through a metric of left atrial volume index, BNP and ejection fraction. MiRNA levels were normalized to global mean and expression compared across pig subtypes and between the two human groups. Results: In the porcine model, miR-208b was upregulated at week 1 (ΔCT= -3.9, pT = -5.5, pT = -1.5, pT = -1.5, pT = -1.5, pT = -1.5, p<0.05). Conclusions: Dysregulation of miR-208b is confirmed in our porcine model and is validated in humans. Prior studies have identified miR-208b in both myosin isoform switching and conduction disease. We theorize that dysregulation of miR-208b may play a critical role in atrial structural remodeling and vulnerability to AF.
