فهرست مطالب zhongping ning

Slit guidance ligand 3 (SLIT3) has been identified as a potential therapeutic regulator against fibroblast activity and fibrillary collagen production in an autocrine manner. However, this research aims to investigate the potential role of SLIT3 in cardiac fibrosis and fibroblast differentiation and its underlying mechanism.

C57BL/6 mice (male, 8-10 weeks, n=47) were subcutaneously infused with Ang II (2.0 mg/kg/day) for 4 weeks. One to two-day-old Sprague-Dawley (SD) rats were anesthetized by intraperitoneal injection of 1% pentobarbital sodium (60 mg/kg) and ketamine (50 mg/kg) and the cardiac fibroblast was isolated aseptically. The mRNA and protein expression were analyzed using RT-qPCR and Western blotting.

The SLIT3 expression level was increased in Ang II-induced mice models and cardiac fibroblasts. SLIT3 significantly increased migrated cells and α-smooth muscle actin (α-SMA) expression in cardiac fibroblasts. Ang II-induced increases in mRNA expression of collagen I (COL1A1), and collagen III (COL3A1) was attenuated by SLIT3 inhibition. SLIT3 knockdown attenuated the Ang II-induced increase in mRNA expression of ACTA2 (α-SMA), Fibronectin, and CTGF. SLIT3 suppression potentially reduced DHE expression and decreased malondialdehyde (MDA) content, and the superoxide dismutase (SOD) and catalase (CAT) levels were significantly increased in cardiac fibroblasts. Additionally, SLIT3 inhibition markedly decreased RhoA and ROCK1 protein expression, whereas ROCK inhibitor Y-27632 (10 μM) markedly attenuated the migration of cardiac fibroblasts stimulated by Ang II and SLIT3.

The results speculate that SLIT3 could significantly regulate cardiac fibrosis and fibroblast differentiation via the RhoA/ROCK1 signaling pathway.

Corilagin (Cor) is reported as beiing hepatoprotective, anti-inflammatory, antibacterial, and anti-oxidant, while the effect on atrial fibrosis remains unknown. Therefore, we investigated the protective effect of Cor in angiotensin II (Ang II)-induced atrial fibrosis and atrial fibrillation (AF).

C57BL/6 mice (male, 8–10 weeks, n = 40) were subcutaneously infused either with saline or Ang II (2.0 mg/kg/day) and Cor (30 mg/kg) intraperitoneally injected 2 hr before Ang II infusion for 4 weeks. Mice were grouped into the control group (n=8), Cor group (n=8), Ang II group (n=8), and Ang II + Cor group (n=8). Morphological, histological, and biochemical examinations were performed. In vivo, transesophageal burst pacing was used to generate AF.

Cor treatment markedly reduced Ang II-induced AF development in mice. Ang II + Cor therapy potentially decreased the atrial fibrotic area. It significantly decreased the increase in smooth muscle alpha-actin (α-SMA), CTGF, Collagen I, and Collagen III expressions brought on by Ang II treatment. Moreover, Ang II + Cor treatment remarkably decreased the malondialdehyde (MDA) content, whereas superoxide dismutase (SOD) and catalase (CAT) activities were potentially increased (all, P<0.001). In addition, Ang II + Cor significantly reduced Ang II-induced interleukin 1 beta (IL-1β), interleukin 6 (IL-6), and tumor necrosis factor-alpha (TNF-α) concentrations in atrial tissues. Furthermore, Cor significantly inhibited Ang II-induced p-PI3K, p-Akt, and NF-κB p-p65 protein expression in atrial tissues. 

Our data speculated that Cor could have a protective effect against Ang II-induced atrial fibrosis and AF via down-regulation of the PI3K-Akt pathway.

Irisin was reported as a cardioprotective and anti-oxidative effector, while the effect on atrial fibrosis is unknown. The current research examined irisin’s function in atrial fibrillation (AF); atrial fibrosis brought on by Ang II can be suppressed, thus lessening the risk of developing AF. 

246 individuals were enrolled in the present case-control study. Chinese AF patients (n=126), 83 of whom were paroxysmal AF (PAF), 43 patients with persistent AF (PeAF), and 120 healthy controls. Saline or Ang II (2.0 mg/kg/day) was subcutaneously injected into healthy male C57BL/6 mice for four weeks. Once daily for four weeks, intraperitoneal injections of exogenous irisin (500 g/kg/day) were administered. 

In comparison to PAF patients and healthy controls (all P<0.05), PeAF patients had significantly higher rates of heart failure (HF), large left atrial size (LAD), hypertrophic protein B-type natriuretic peptide (BNP), malondialdehyde (MDA), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), C-terminal telopeptide of type I collagen (CTX-I), and transforming growth factor beta-1 (TGF-β1), while superoxide dismutase (SOD) level was low. Expression of irisin was decreased in AF patients’ serum and Ang II-infused mice. Exogenous irisin dramatically reduced apoptosis, atrial fibrosis, atrial inflammation, and the susceptibility to AF caused by Ang II. In the atrial tissue, irisin inhibited Ang II-induced fibroblast transdifferentiation, LOXL2, TGF-β1, collagen production, and phosphorylation of Smad2/3. 

The study results speculated that irisin could be a potential AF target, and it inhibited atrial fibrosis and significantly impaired increased AF susceptibility through inactivation of LOXL2 and the TGF-β/Smad pathway.

The present study’s objective was to investigate the association between angiopoietin-like 4 (ANGPTL4) levels and the prognosis of Atrial fibrillation (AF), the causative effect in angiotensin II- (Ang II) induced AF, and its underlying mechanisms.

Baseline serum ANGPTL-4 concentrations were measured in 130 patients with AF. Rat atrial fibroblasts were isolated from 14-day-old SD rats and transfected with Ang II treatment. Transfected cells were divided into: The control group, ANGPTL4-OE group, Ang II group, and Ang II+ANGPTL4-OE group. Transfected cells were used to analyze fibroblasts’ proliferation, migration, and collagen production at the cellular level. RT-qPCR and western blotting evaluated the ANGPTL4-targeted gene and PPARγ-Akt pathway.

In patients with AF, serum ANGPTL4 concentrations decreased significantly compared with the healthy group. ANGPTL4 mRNA and protein expressions were significantly down-regulated in Ang II-induced cardiac fibroblasts. ANGPTL4 overexpression potentially attenuated Ang II‑induced fibroblast proliferation, migration, and collagen production in atrial tissue. ANGPTL4 inhibited the signaling proteins, such as PPARγ, α-SMA, and Akt.

Our experimental data speculate that ANGPTL4 is a key factor in regulating AF progression. Therefore, increasing ANGPTL4 expression could be an effective strategy for AF treatment.v

Cardiac fibrosis is a key biological process of cardiac remodeling and heart failure. Fatty acid-binding protein 4 (FABP4) is a lipid-binding protein that can regulate glucose and lipid homeostasis, and its expression was elevated in heart failure. However, whether FABP4 is involved in cardiac fibrosis remains unknown. 

The cardiac fibrosis model was established in male C57BL/6 mice with subcutaneously infused angiotensin II (Ang-II) (2.8 mg/kg/day) for 4 weeks. DMSO or FABP4 inhibitor BMS309403 (50 mg/kg/day) was intraperitoneally injected for 4 weeks. Ang II-infused mice, FABP4 inhibitor (BMS309403) injected mice, and ventricular tissue were used for morphological studies, and histological and biochemical analyses (FABP4 protein composition and expression).

Ang II infusion increased FABP4 mRNA and protein expression in the mouse ventricular tissue. After treatment with FABP4 inhibitor BMS309403 for 4 weeks, mice showed improved cardiac structure and function as detected by echocardiography. BMS309403 suppressed cardiac and systemic inflammatory response, reduced collagen deposition, and mRNA expression of collagen type I (COL1A1) and collagen type III (COL3A1) in Ang II-infused mice. BMS309403 also reduced the number of α-smooth muscle actin (α-SMA)+cells and decreased the mRNA expression of α-SMA, matrix metalloproteinases-2 (MMP-2), MMP-9, and transforming growth factor-β (TGF‑β) in ventricular tissue.

The inhibitory effect of BMS309403 on cardiac fibrosis might be associated with inhibition of NLRP3 inflammasome activation, which Ang II activated. Thus, our data speculated that inhibition of FABP4 could significantly induce cardiac fibrosis.

Atrial fibrillation (AF) is a common arrhythmia with atrial myocyte hypertrophy linked with stroke, heart failure, and increased mortality. Lysyl oxidase-like 2 (LOXL2) involves the cross-linking of collagen in the extracellular matrix (ECM). In the present study, we investigated the roles and underlying mechanisms of LOXL2 on cardiomyocyte hypertrophy.  The expression of LOXL2 mRNA and protein were detected in angiotensin II (Ang II) treated rat cardiomyocytes H9c2 by RT-qPCR and western blot. Small interfering RNA (siRNA) mediated LOXL2 gene silencing was used to evaluate cardiac hypertrophy and related markers. Also, the protein expression of EMT markers and Smad3/NF-κB pathway was determined by western blot.  Ang II significantly increased mRNA and protein expressions of LOXL2 and increased mRNA levels of myocardial hypertrophy markers, including ANP, BNP, and β-MHC in H9c2 cells. Silencing of LOXL2 significantly suppressed Ang II-induced hypertrophy and reversed the increase in ANP, BNP, and β-MHC mRNA levels. Also, EMT markers’ expressions, as evidenced by increased E-cadherin and decreased vimentin, α-smooth muscle actin (α-SMA), fibroblast-specific protein (FSP), and collagen 1A1. Mechanistically, we found that LOXL2 silencing suppressed protein expressions of TGF-β1, p-Smad3, and p-NF-κB in Ang II-stimulated H9c2 cells. LOXL2 silencing also attenuated Ang II-induced increased expression and content of proinflammatory cytokines IL-1β (H) and TNF-α.  Our data speculated that LOXL2 might be a potential contributing factor to Ang II-induced cardiac hypertrophy, and TGF-β1/Smad3/NF-κB is involved in a signal axis and might be a potential strategy in treating cardiac hypertrophy.