Alterations of Myocardial Mitochondrial Morphology and Function in a Canine Model of Premature Ventricular Contractions-Induced Cardiomyopathy.

AIMS: Changes in myocardial mitochondrial morphology and function in premature ventricular contractions (PVCs)-induced cardiomyopathy (PVCCM) remain poorly studied. Here, we investigated the effects of PVCs with different coupling intervals (CIs) on myocardial mitochondrial remodelling in a canine model of PVCCM. METHODS AND RESULTS: Twenty-one beagles underwent pacemaker implantation and were randomised into the sham (n = 7), short-coupled PVCs (SCP, n = 7), and long-coupled PVCs (LCP, n = 7) groups. Right ventricular (RV) apical bigeminy was produced for 12-week to induce PVCCM in the SCP (CI, 250 ms) and LCP (CI, 350 ms) groups. Echocardiography was performed at baseline and biweekly thereafter to evaluate cardiac function. Masson's trichrome staining measured ventricular interstitial fibrosis. The ultrastructural morphology of the myocardial mitochondria was analysed using transmission electron microscopy. Mitochondrial Ca2+ concentration, reactive oxygen species (ROS) levels, adenosine triphosphate (ATP) content, membrane potential, and electron transport chain (ETC) complex activity were measured to assess myocardial mitochondrial function. Twelve-week-PVCs led to left ventricular (LV) enlargement with systolic dysfunction, disrupted mitochondrial morphology, increased mitochondrial Ca2+ concentration and ROS levels, decreased mitochondrial ATP content and membrane potential, and impaired ETC complex activity in both the SCP and LCP groups (all p < 0.01 vs the sham group). Ventricular fibrosis was observed only in canines with LCP. Worse cardiac function and more pronounced abnormalities in mitochondrial morphology and function were observed in the LCP group than to the SCP group (all p < 0.05). CONCLUSION: We demonstrated myocardial mitochondrial abnormalities in dogs with PVCCM, characterised by abnormal mitochondrial morphology, mitochondrial Ca2+ overload, oxidative stress, and impaired mitochondrial energy metabolism. Compared to SCP, long-term LCP exposure resulted in more severe mitochondrial remodelling and cardiac dysfunction in dogs.

Serinc2 deficiency exacerbates sepsis-induced cardiomyopathy by enhancing necroptosis and apoptosis.

In critical care medicine, sepsis is a potentially fatal syndrome characterized by multi-organ dysfunction and eventual failure. Sepsis-induced cardiomyopathy (SIC) is characterized by decreased venstricular contractility. Serine incorporator 2 (Serinc2) is a protein involved in phosphatidylserine biosynthesis and membrane incorporation. It may also be a protective factor in septic lung injury. However, it is unknown whether Serinc2 influences SIC onset or progression. In the present study, we found that Serinc2 was downregulated in the cardiomyocytes of cecal ligation and puncture (CLP)-induced SIC and in neonatal rat cardiomyocytes (NRCMs) exposed to lipopolysaccharides (LPS). Serinc2 knockout (KO) exacerbated sepsis-induced myocardial inflammation, necroptosis, apoptosis, myocardial damage, and contractility impairment. Furthermore, the lack of Serinc2 in cardiomyocytes aggravated LPS-induced cardiomyopathic inflammation, necroptosis, and apoptosis. An adenovirus overexpressing Serinc2 inhibited the inflammatory response and favored cardiomyocyte survival. A mechanistic analysis revealed that Serinc2 deficiency exacerbated LPS-induced cardiac dysfunction by inhibiting the protein kinase B (Akt)/glycogen synthase kinase 3 beta (GSK-3ß) signaling pathway that regulates necrotic complex formation and apoptotic pathways in cardiomyopathy. The findings of the present work demonstrated that Serinc2 plays an essential role in SIC and is, therefore, promising as a prophylactic and therapeutic target for this condition.

Iron and atrial fibrillation: A review.

Atrial fibrillation (AF), one of the most common arrhythmias in clinical practice, is classified into paroxysmal, persistent, and permanent AF according to its duration. The development of AF is associated with increased cardiovascular morbidity and mortality. However, the exact etiology of this disease remains poorly understood. Recent studies found disorders of iron metabolism might be involved in the progression of AF. Abnormal iron metabolism in cardiomyocytes provides arrhythmogenic substrates through a variety of mechanisms, including calcium mishandling, ion channel remodeling, and oxidative stress overaction. Interestingly, in AF patients with iron overload, interventions on iron metabolism, such as iron chelators and ferroptosis inhibitors, has been shown to prevent AF via reducing ferroptosis. Herein, we review the possible mechanisms, consequences, and therapeutic implications of altered atrial iron handling for AF pathophysiology.

AGEs induce endothelial cells senescence and endothelial barrier dysfunction via miR-1-3p/MLCK signaling pathways.

Advanced glycation end products (AGEs) disturb endothelial barrier function and contribute to age-related diseases. As microRNAs (miRNAs) are potential therapeutic agents, targeting AGEs-associated signaling using miRNAs in endothelial cells may be an effective intervention strategy for age-related vascular disorders. This study investigated the effects of AGEs on the endothelial cell senescence and barrier function in human umbilical vein endothelial cells (HUVECs). HUVECs were treated with AGEs and transfected with miRNA-1-3p mimics to induce overexpression of miR-1-3p. Senescence-associated ß-galactosidase (SA-ß-Gal) staining and senescence-related proteins P53, P21, and P16 were detected to evaluate the endothelial cell senescence. The expression levels of myosin light chain kinase (MLCK) signaling and transendothelial electric resistance (TEER) were used to indicate endothelial barrier function. AGEs significantly increased SA-ß-gal staining-positive cells accompanied by the upregulation of P53, P21, and P16 expression. AGEs also damaged endothelial barrier function by decreasing TEER and increasing zonula occludens protein 1, p-MLC/MLC, and MLCK. miRNA-1-3p was significantly reduced in HUVECs treated with AGEs. miR-1-3p overexpression decreased MLCK signal and improved AGEs-induced endothelial barrier function impairment. Meanwhile, miR-1-3p overexpression ameliorated oxidative stress and endothelial cell senescence induced by AGEs. AGEs induced endothelial cell senescence and endothelial barrier dysfunction by regulating miR-1-3p/MLCK signaling pathway.

Loureirin B alleviates cardiac fibrosis by suppressing Pin1/TGF-ß1 signaling.

It is well-established that cardiac fibrosis contributes to cardiac dysfunction and adverse outcomes. However, the underlying mechanisms remain elusive, warranting further studies to develop new therapeutic strategies. It has been suggested that loureirin B can ameliorate the progression of fibrotic diseases. This study investigated the effects of loureirin B on cardiac fibrosis and explored the underlying mechanisms. Transverse aortic constriction (TAC) was performed to induce cardiac fibrosis in mice. Loureirin B (10 mg/kg/day) or saline was continuously delivered via subcutaneous osmotic mini-pumps. Cardiac fibroblasts (CFs) were treated with angiotensin II (Ang II, 100 nM, 24 h) to simulate fibrosis in vitro. Immunochemistry, echocardiography, and Sircol collagen assays were conducted to evaluate the cardioprotective effects. Quantitative real-time polymerase chain reaction, Western blot, and transfection techniques were performed to elucidate the mechanisms. Results showed that loureirin B prevented cardiac fibrosis and improved cardiac function in mice subjected to TAC. Treatment with loureirin B inhibited the elevation of inflammatory factors (interleukin-1ß, interleukin-6, and tumor necrosis factor-α), transforming growth factor-ß1 (TGF-ß1), and Pin1 induced by TAC. Furthermore, loureirin B treatment inhibited the increased fibroblast activation and collagen synthesis induced by Ang II in CFs. In addition, loureirin B inhibited increased expression of TGF-ß1 and Pin1 induced by Ang II or TAC. Mechanistically, overexpression of Pin1 induced increased TGF-ß1 expression and blocked the anti-fibrotic effects in Ang II-induced CFs treated with loureirin B. Loureirin B ameliorated cardiac fibrosis and dysfunction both in vitro and in vivo probably through the Pin1/TGF-ß1 signaling pathway.

ß-adrenergic activation may promote myosin light chain kinase degradation through calpain in pressure overload-induced cardiac hypertrophy: ß-adrenergic activation results in MLCK degradation.

BACKGROUND: ß-adrenergic activation is able to exacerbate cardiac hypertrophy. Myosin light chain kinase (MLCK) and its phosphorylated substrate, phospho-myosin light chain 2 (p-MLC2), play vital roles in regulating cardiac hypertrophy. However, it is not yet clear whether there is a relationship between ß-adrenergic activation and MLCK in the progression of cardiac hypertrophy. Therefore, we explored this relationship and the underlying mechanisms in this work. METHODS: Cardiac hypertrophy and cardiomyocyte hypertrophy were induced by pressure overload and isoproterenol (ISO) stimulation, respectively. Echocardiography, histological analysis, immunofluorescence and qRT-PCR were used to confirm the successful establishment of the models. A ß-blocker (metoprolol) and a calpain inhibitor (calpeptin) were administered to inhibit ß-adrenergic activity in rats and calpain in cardiomyocytes, respectively. The protein expression levels of MLCK, myosin light chain 2 (MLC2), p-MLC2, myosin phosphatase 2 (MYPT2), calmodulin (CaM) and calpain were measured using western blotting. A cleavage assay was performed to assess the degradation of recombinant human MLCK by recombinant human calpain. RESULTS: The ß-blocker alleviated cardiac hypertrophy and dysfunction, increased MLCK and MLC2 phosphorylation and decreased calpain expression in pressure overload-induced cardiac hypertrophy. Additionally, the calpain inhibitor calpeptin attenuated cardiomyocyte hypertrophy, upregulated MLCK and p-MLC2 and reduced MLCK degradation in ISO-induced cardiomyocyte hypertrophy. Recombinant human calpain degraded recombinant human MLCK in vitro in concentration- and time-dependent manners, and this degradation was inhibited by the calpain inhibitor calpeptin. CONCLUSION: Our study suggested that ß-adrenergic activation may promote the degradation of MLCK through calpain in pressure overload-induced cardiac hypertrophy.

Effect of the Shensong Yangxin Capsule on Energy Metabolism in Angiotensin II-Induced Cardiac Hypertrophy.

BACKGROUND: Shensong Yangxin Capsule (SSYX), traditional Chinese medicine, has been used to treat arrhythmias, angina, cardiac remodeling, cardiac fibrosis, and so on, but its effect on cardiac energy metabolism is still not clear. The objective of this study was to investigate the effects of SSYX on myocardium energy metabolism in angiotensin (Ang) II-induced cardiac hypertrophy. METHODS: We used 2 µl (10-6 mol/L) AngII to treat neonatal rat cardiomyocytes (NRCMs) for 48 h. Myocardial α-actinin staining showed that the myocardial cell volume increased. Expression of the cardiac hypertrophic marker-brain natriuretic peptide (BNP) messenger RNA (mRNA) also increased by real-time polymerase chain reaction (PCR). Therefore, it can be assumed that the model of hypertrophic cardiomyocytes was successfully constructed. Then, NRCMs were treated with 1 µl of different concentrations of SSYX (0.25, 0.5, and 1.0 µg/ml) for another 24 h. To explore the time-depend effect of SSYX on energy metabolism, 0.5 µg/ml SSYX was added into cells for 0, 6, 12, 24, and 48 h. Mitochondria was assessed by MitoTracker staining and confocal microscopy. mRNA and protein expression of mitochondrial biogenesis-related genes - Peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), energy balance key factor - adenosine monophosphate-activated protein kinase (AMPK), fatty acids oxidation factor - carnitine palmitoyltransferase-1 (CPT-1), and glucose oxidation factor - glucose transporter- 4 (GLUT-4) were measured by PCR and Western blotting analysis. RESULTS: With the increase in the concentration of SSYX (from 0.25 to 1.0 µg/ml), an increased mitochondrial density in AngII-induced cardiomyocytes was found compared to that of those treated with AngII only (0.25 µg/ml, 18.3300 ± 0.8895 vs. 24.4900 ± 0.9041, t = 10.240, P < 0.0001; 0.5 µg/ml, 18.3300 ± 0.8895 vs. 25.9800 ± 0.8187, t = 12.710, P < 0.0001; and 1.0 µg/ml, 18.3300 ± 0.8895 vs. 24.2900 ± 1.3120, t = 9.902, P < 0.0001; n = 5 per dosage group). SSYX also increased the mRNA and protein expression of PGC-1α (0.25 µg/ml, 0.8892 ± 0.0848 vs. 1.0970 ± 0.0994, t = 4.319, P = 0.0013; 0.5 µg/ml, 0.8892 ± 0.0848 vs. 1.2330 ± 0.0564, t = 7.150, P < 0.0001; and 1.0 µg/ml, 0.8892 ± 0.0848 vs. 1.1640 ± 0.0755, t = 5.720, P < 0.0001; n = 5 per dosage group), AMPK (0.25 µg/ml, 0.8872 ± 0.0779 vs. 1.1500 ± 0.0507, t = 7.239, P < 0.0001; 0.5 µg/ml, 0.8872 ± 0.0779 vs. 1.2280 ± 0.0623, t = 9.379, P < 0.0001; and 1.0 µg/ml, 0.8872 ± 0.0779 vs. 1.3020 ± 0.0450, t = 11.400, P < 0.0001; n = 5 per dosage group), CPT-1 (1.0 µg/ml, 0.7348 ± 0.0594 vs. 0.9880 ± 0.0851, t = 4.994, P = 0.0007, n = 5), and GLUT-4 (0.5 µg/ml, 1.5640 ± 0.0599 vs. 1.7720 ± 0.0660, t = 3.783, P = 0.0117; 1.0 µg/ml, 1.5640 ± 0.0599 vs. 2.0490 ± 0.1280, t = 8.808, P < 0.0001; n = 5 per dosage group). The effect became more obvious with the increasing concentration of SSYX. When 0.5 µg/ml SSYX was added into cells for 0, 6, 12, 24, and 48 h, the expression of AMPK (6 h, 14.6100 ± 0.6205 vs. 16.5200 ± 0.7450, t = 3.456, P = 0.0250; 12 h, 14.6100 ± 0.6205 vs. 18.3200 ± 0.9965, t = 6.720, P < 0.0001; 24 h, 14.6100 ± 0.6205 vs. 21.8800 ± 0.8208, t = 13.160, P < 0.0001; and 48 h, 14.6100 ± 0.6205 vs. 23.7400 ± 1.0970, t = 16.530, P < 0.0001; n = 5 per dosage group), PGC-1α (12 h, 11.4700 ± 0.7252 vs. 16.9000 ± 1.0150, t = 7.910, P < 0.0001; 24 h, 11.4700 ± 0.7252 vs. 20.8800 ± 1.2340, t = 13.710, P < 0.0001; and 48 h, 11.4700 ± 0.7252 vs. 22.0300 ± 1.4180, t = 15.390; n = 5 per dosage group), CPT-1 (24 h, 15.1600 ± 1.0960 vs. 18.5800 ± 0.9049, t = 6.048, P < 0.0001, n = 5), and GLUT-4 (6 h, 10.2100 ± 0.9485 vs. 12.9700 ± 0.8221, t = 4.763, P = 0.0012; 12 h, 10.2100 ± 0.9485 vs. 16.9100 ± 0.8481, t = 11.590, P < 0.0001; 24 h, 10.2100 ± 0.9485 vs. 19.0900 ± 0.9797, t = 15.360, P < 0.0001; and 48 h, 10.2100 ± 0.9485 vs. 14.1900 ± 0.9611, t = 6.877, P < 0.0001; n = 5 per dosage group) mRNA and protein increased gradually with the prolongation of drug action time. CONCLUSIONS: SSYX could increase myocardial energy metabolism in AngII-induced cardiac hypertrophy. Therefore, SSYX might be considered to be an alternative therapeutic remedy for myocardial hypertrophy.

Evaluation of 6-chloro-N-[3,4-disubstituted-1,3-thiazol-2(3H)-ylidene]-1,3-benzothiazol-2-amine Using Drug Design Concept for Their Targeted Activity Against Colon Cancer Cell Lines HCT-116, HCT15, and HT29.

BACKGROUND Colorectal adenocarcinoma is the second leading cause of cancer-related death in the world. The stage of the disease is related to the survival of the patient, and in early phases surgery is the main modality of treatment. The main aim of modern medicinal chemistry is to synthesize small molecules via drug designing, especially by targeting tumor cells. MATERIAL AND METHODS A new series of 19 compounds containing benzothiazole and thiazole were designed. Molecular docking studies were performed on the designed series of molecules. Compounds showing good binding affinity towards the EGFR receptor were selected for synthetic studies. Characterization of the synthesized compounds was done by FTIR, 1HNMR, Mass and C, H, N, analysis. RESULTS The anticancer evaluation of the synthesized compounds was done at NIC, USA at a single dose against colon cancer cell lines HCT 116, HCT15, and HC 29. The active compounds were further evaluated for the 5-dose testing. Compounds were designed by using docking analysis. To ascertain the interaction of EGFR tyrosine kinase binding, energy calculation was used. CONCLUSIONS The results of the present study indicate that the designed compounds show good activity against colon cancer cell lines, which may be further studied to design new potential molecules.

The serum matrix metalloproteinase-9 level is an independent predictor of recurrence after ablation of persistent atrial fibrillation

OBJECTIVES: This study investigated whether the serum matrix metalloproteinase-9 level is an independent predictor of recurrence after catheter ablation for persistent atrial fibrillation. METHODS: Fifty-eight consecutive patients with persistent atrial fibrillation were enrolled and underwent catheter ablation. The serum matrix metalloproteinase-9 level was detected before ablation and its relationship with recurrent arrhythmia was analyzed at the end of the follow-up. RESULTS: After a mean follow-up of 12.1±7.2 months, 21 (36.2%) patients had a recurrence of their arrhythmia after catheter ablation. At baseline, the matrix metalloproteinase-9 level was higher in the patients with recurrence than in the non-recurrent group (305.77±88.90 vs 234.41±93.36 ng/ml, respectively, p=0.006). A multivariate analysis showed that the matrix metalloproteinase-9 level was an independent predictor of arrhythmia recurrence, as was a history of atrial fibrillation and the diameter of the left atrium. CONCLUSION: The serum matrix metalloproteinase-9 level is an independent predictor of recurrent arrhythmia after catheter ablation in patients with persistent atrial fibrillation.