rat-model-right-sided-cardiac-remodeling-arrhythmia-using-pulmonary

Rat Model of Right-Sided Cardiac Remodeling and Arrhythmia Using Pulmonary Artery Banding

Clinical conditions, including chronic obstructive pulmonary disease or pulmonary arterial hypertension (PAH), can lead to chronic right ventricle ...

Montreal Heart Institute

Inflammation is a complex program of active processes characterized by the well-orchestrated succession of an initiation and a resolution phase aiming to promote homeostasis. When the resolution of inflammation fails, the tissue undergoes an unresolved inflammatory status which, if it remains uncontrolled, can lead to chronic inflammatory disorders due to aggravation of structural damages, development of a fibrous area, and loss of function. Various human conditions show a typical unresolved inflammatory profile. Inflammatory diseases include cancer, neurodegenerative disease, asthma, right heart disease, atherosclerosis, myocardial infarction, or atrial fibrillation. New evidence has started to emerge on the role, including pro-resolution involvement of chemical mediators in the acute phase of inflammation. Although flourishing knowledge is available about the role of specialized pro-resolving mediators in neurodegenerative diseases, atherosclerosis, obesity, or hepatic fibrosis, little is known about their efficacy to combat inflammation-associated arrhythmogenic cardiac disorders. It has been shown that resolvins, including RvD1, RvE1, or Mar1, are bioactive mediators of resolution. Resolvins can stop neutrophil activation and infiltration, stimulate monocytes polarization into anti-inflammatory-M2-macrophages, and activate macrophage phagocytosis of inflammation-debris and neutrophils to promote efferocytosis and clearance. This review aims to discuss the paradigm of failed-resolution mechanisms (FRM) potentially promoting arrhythmogenicity in right heart disease-induced inflammatory status.

Evidence of Failed Resolution Mechanisms in Arrhythmogenic Inflammation, Fibrosis and Right Heart Disease.

The present study tested the hypothesis that protein kinase C-α (PKC-α) recruitment in the presence of the p38α/β MAPK inhibitor SB203580 facilitated the appearance and cell cycle re-entry of nestin-neonatal rat ventricular cardiomyocytes (NNVMs) and induced a transcript profile delineating a proliferative phenotype. Phorbol 12,13-dibutyrate (PDBu) treatment did not induce de novo nestin expression or increase the cell cycle re-entry of 1-day-old NNVMs but significantly increased runt-related transcription factor 1 (Runx1) and p16 cell cycle inhibitor (CDKN2a) mRNA levels and downregulated epithelial cell transforming 2 (ECT2) mRNA expression. SB203580 administration to PDBu-treated NNVMs induced de novo nestin expression, preferentially increased the density (normalized to 500 NNVMs) of nestin-NNVMs that incorporated 5-bromo-2'-deoxyuridine (PDBu, 1.4 ± 3 vs. PDBu/SB203580, 128 ± 34;  = 5 independent litters), significantly inhibited CDKN2a and Runx1 mRNA upregulation and reversed ECT2 mRNA downregulation. PDBu treatment of NNVMs reduced PKC-α, protein kinase-δ (PKC-δ) and protein kinase-ε (PKC-ε) protein levels and GF109203X (conventional PKC isoform inhibitor) selectively attenuated PKC-α protein downregulation. GF109203X administration to PDBu/SB203580-treated NNVMs significantly reduced the density of nestin-NNVMs that incorporated 5-bromo-2'-deoxyuridine (PDBu/SB203580/GF109203X, 40 ± 46;  = 5). Moreover, GF109203X/PDBu/SB203580 treatment unmasked the predominant appearance of a separate NNVM population that incorporated 5-bromo-2'-deoxyuridine (PDBu/SB203580/GF109203X, 192 ± 42;  = 5) delineated by the absence of de novo nestin expression. Sotrastaurin (conventional/novel PKC isoform inhibitor) administration to PDBu/SB203580-treated NNVMs significantly attenuated the density of nestin-NNVMs (PDBu/SB203580/sotrastaurin, 8 ± 10;  = 4) and nestin-NNVMs (PDBu/SB203580/sotrastaurin, 64 ± 30;  = 4) that incorporated 5-bromo-2'-deoxyuridine. These data reveal that the neonatal rat heart contains at least two separate populations of NNVMs that re-enter the cell cycle and the preferential appearance of nestin- or nestin-NNVMs is driven by distinct PKC isoforms in the presence of SB203580. The appearance of nestin-neonatal rat ventricular cardiomyocytes that re-entered the cell cycle following phorbol ester stimulation in the presence of p38α/β MAPK inhibitor SB203580 was associated with the inhibition of Runx1 and CDKN2a mRNA upregulation. PKC-α selectively induced the cell cycle re-entry of nestin-neonatal rat ventricular cardiomyocytes. Pharmacological inhibition of PKC-α with concomitant p38α/β MAPK suppression unmasked the cell cycle re-entry of a second population of neonatal rat ventricular cardiomyocytes in the absence of nestin expression.

Distinct protein kinase C isoforms drive the cell cycle re-entry of two separate populations of neonatal rat ventricular cardiomyocytes.

Recent studies suggest that bioactive mediators called resolvins promote an active resolution of inflammation. Inflammatory signalling is involved in the development of the substrate for atrial fibrillation (AF). The aim of this study is to evaluate the effects of resolvin-D1 on atrial arrhythmogenic remodelling resulting from left ventricular (LV) dysfunction induced by myocardial infarction (MI) in rats.

An inflammation resolution-promoting intervention prevents atrial fibrillation caused by left ventricular dysfunction.

Right heart disease (RHD), characterized by right ventricular (RV) and atrial (RA) hypertrophy, and cardiomyocytes' (CM) dysfunctions have been described to be associated with the incidence of atrial fibrillation (AF). Right heart disease and AF have in common, an inflammatory status, but the mechanisms relating RHD, inflammation, and AF remain unclear. We hypothesized that right heart disease generates electrophysiological and morphological remodelling affecting the CM, leading to atrial inflammation and increased AF susceptibility.

Charles-Alexandre LeBlanc

Montreal Heart Institute

Rat Model of Right-Sided Cardiac Remodeling and Arrhythmia Using Pulmonary Artery Banding