High glucose levels accelerate atherosclerosis via NLRP3-IL/ MAPK/NF-κB-related inflammation pathways.

BACKGROUND: As a chronic inflammatory disease, diabetes mellitus (DM) contributes to the development of atherosclerosis (AS). However, how the NLRP3 inflammasome participates in diabetes-related AS remains unclear. Therefore, this study aimed to elucidate the mechanism through which NLRP3 uses high glucose (HG) levels to promote AS. METHODS: Serum and coronary artery tissues were collected from coronary artery disease (CAD) patients with and without DM, respectively. The expression of NLRP3 was detected, and the effects of this inflammasome on diabetes-associated AS were evaluated using streptozotocin (STZ)-induced diabetic apoE-/- mice injected with Adenovirus-mediated NLRP3 interference (Ad-NLRP3i). To elucidate the potential mechanism involved, ox-LDL-irritated human aortic smooth muscle cells were divided into the control, high-glucose, Si-NC, and Si-NLRP3 groups to observe the changes induced by downregulating NLRP3 expression. For up-regulating NLRP3, control and plasmid contained NLRP3 were used. TNF-α, IL-1ß, IL-6, IL-18, phosphorylated and total p38, JNK, p65, and IκBα expression levels were detected following the downregulation or upregulation of NLRP3 expression. RESULTS: Patients with comorbid CAD and DM showed higher serum levels and expression of NLRP3 in the coronary artery than those with only CAD. Moreover, mice in the Ad-NLRP3i group showed markedly smaller and more stable atherosclerotic lesions compared to those in other DM groups. These mice had decreased inflammatory cytokine production and improved glucose tolerance, which demonstrated the substantial effects of NLRP3 in the progression of diabetes-associated AS. Furthermore, using the siRNA or plasmid to downregulate or upregulate NLRP3 expression in vitro altered cytokines and the MAPK/NF-κB pathway. CONCLUSIONS: NLRP3 expression was significantly increased under hyperglycemia. Additionally, it accelerated AS by promoting inflammation via the IL/MAPK/NF-κB pathway.

Comparative effectiveness and safety of DOACs vs. VKAs in treatment of left ventricular thrombus- a meta-analysis update.

BACKGROUND AND OBJECTIVE: Left ventricular thrombus (LVT) formation in patients with acute myocardial infarction (AMI) or cardiomyopathies is not uncommon. The optimal oral anticoagulation therapy for resolving LVT has been under intense debate. Vitamin K antagonists (VKAs) remain the anticoagulant of choice for this condition, according to practice guidelines. Evidence supporting the use of direct oral anticoagulants (DOACs) in the management of LVT continues to grow. We performed a systematic review and meta-analysis to compare the efficacy and safety of DOACs versus VKAs. METHODS: A comprehensive literature search was carried out in PubMed, Cochrane Library, Web of Science, Embase, and Scopus databases in July 2023. The efficacy outcomes of this study were thrombus resolution, ischemic stroke, systemic embolism, stroke/systemic embolism, all-cause mortality, and adverse cardiovascular events. The safety outcomes were any bleeding, major bleeding, and intracranial hemorrhage. A total of twenty-seven eligible studies were included in the meta-analysis. Data were analyzed utilizing Stata software version 15.1. RESULTS: There was no significant difference between DOACs and VKAs with regard to LVT resolution (RR = 1.00, 95% CI 0.95-1.05, P = 0.99). In the overall analysis, DOACs significantly reduced the risk of stroke (RR = 0.74, 95% CI 0.57-0.96, P = 0.021), all-cause mortality (RR = 0.70, 95% CI 0.57-0.86, P = 0.001), any bleeding (RR = 0.75, 95% CI 0.61-0.92, P = 0.006) and major bleeding (RR = 0.67, 95% CI 0.52-0.85, P = 0.001) when compared to VKAs. Meanwhile, in the sub-analysis examining randomized controlled trials (RCTs), the aforementioned outcomes no longer differed significantly between the DOACs and VKAs groups. The incidences of systemic embolism (RR = 0.81, 95% CI 0.54-1.22, P = 0.32), stroke/systemic embolism (RR = 0.85, 95% CI 0.72-1.00, P = 0.056), intracranial hemorrhage (RR = 0.59, 95% CI 0.23-1.54, P = 0.28), and adverse cardiovascular events (RR = 0.99, 95% CI 0.63-1.56, P = 0.92) were comparable between the DOACs and VKAs groups. A subgroup analysis showed that patients treated with rivaroxaban had a significantly lower risk of stroke (RR = 0.24, 95% CI 0.08-0.72, P = 0.011) than those in the VKAs group. CONCLUSION: With non-inferior efficacy and superior safety, DOACs are promising therapeutic alternatives to VKAs in the treatment of LVT. Further robust investigations are warranted to confirm our findings.

Western blot normalization: Time to choose a proper loading control seriously.

Recent research has questioned the validity of housekeeping proteins in Western blot. Our present study proposed new ideas for Western blot normalization that improved the reproducibility of scientific research. We used the Gene Expression Omnibus (GEO) database and the web tool GEO2R to exclude unstable housekeeping genes quickly. In ischemic heart tissues, actin and tubulin changed significantly, whereas no statistically significant changes were observed in the expression of genes relative to glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Besides, the reliability of GAPDH was further examined by Western blot. Additionally, unstable housekeeping genes were found in other animal models of cardiovascular medicine. We also found that sodium dodecyl sulfate and temperature significantly impacted the results of Ponceau S staining. Membranes stained with Ponceau S after immunodetection could avoid this interference, and the coefficients of variation for post-immunodetection staining are lower than those produced by GAPDH immunodetection. Overall, we described a new use of differential gene expression analysis and proposed a modified Ponceau S staining method, which provided researchers with a proper loading control for Western blot and hence could improve reproducibility in research.

The risk factors of thrombus formation and the effect of catheter ablation on repetitive thrombus formation in patients with atrial fibrillation: a single center retrospective study in China.

BACKGROUND: Atrial fibrillation (AF) predisposes patients to the formation of atrial thrombi. The CHA2DS2-VASc score does not include all risk factors for atrial thrombosis. The present study is designed to explore the influencing factors of thrombus formation in patients with AF and to investigate the effect of catheter ablation (CA) on recurrent thrombosis in patients with a history of intracardiac thrombus. METHODS: (1) This study consisted of 1726 patients that underwent CA, among which 58 patients had a history of intracardiac thrombus prior to CA. The risk factors for thrombus formation were explored by comparing the baseline clinical characteristics of patients with and without atrial thrombus. (2) The left atrial appendage flow velocity (LAAFV) in patients with a history of intracardiac thrombus who were willing to undergo transesophageal echocardiography (TEE) at the latest follow-up were examined, and comparisons of the LAAFV was made before and after CA. RESULTS: The median follow-up period is 13 months. Persistent AF was found to be the only independent risk factor affecting the formation of atrial thrombus among the investigated factors (OR 3.152; 95%CI 1.806-5.500; p < 0.001). Twenty-seven patients agreed to undergo TEE during follow-up, no clinical ischemic stroke events were recorded, no recurrent intracardiac thrombus formation was detected in patients, 15 patients maintained sinus rhythm (55.6%) during follow-up; successful CA significantly increased LAAFV (difference between latest evaluation prior to CA 17.46 ± 14.81 cm/s, p < 0.001). CONCLUSIONS: Persistent AF is the only independent risk factor for thrombus formation. Successful CA may improve the LAAFV and thereby decrease the risk of intracardiac thrombus formation.

Left atrial appendage occlusion using the LAmbre device in atrial fibrillation patients with a history of ischemic stroke: 1-Year outcomes from a multicenter study in China.

BACKGROUND: Patients with non-valvular atrial fibrillation (NVAF) and previous stroke have a significantly higher risk of stroke recurrence. This study aimed to examine the safety and efficacy of the LAmbre left atrial appendage occlusion device in NVAF patients with a history of stroke. METHODS: We examined 103 consecutive NVAF patients in 11 Chinese medical centers who had a history of stroke or transient ischemic attacks (TIA) and underwent placement of the LAmbre device. Follow-up was conducted 1, 3, 6, and 12 months after the procedure. The primary endpoints were the incidence of new ischemic or hemorrhagic stroke, TIA, systemic embolism, or cardiac death. Secondary endpoints were serious perioperative or device-related complications and cerebral, gastrointestinal, or other bleeding events requiring transfusion of at least 2 units of packed red blood cells. RESULTS: Mean patient age was 67.63 ± 7.14 years; mean CHA2DS2-VASc score was 4.72 ± 1.18 and mean HAS-BLED score was 1.90 ± 1.00. LAmbre device placement was successful in 101 patients (98.05%). Mean follow-up was 12.2 months. Five patients (4.95%) developed a new pericardial effusion after the procedure; none required treatment. Eighty-six patients (85.15%) exhibited no peri-device leak (PDL). However, 13 (12.8%) had a small (0-3 mm) PDL and two (2.3%) had a moderate PDL (3-5 mm). One recurrent stroke occurred during follow-up (1.1%). No other complications occurred. CONCLUSIONS: This multicenter study shows the safety and efficacy of LAmbre left atrial appendage occlusion for NVAF patients with a history of stroke or TIA.

Chinese expert consensus on the construction of the fluoroless cardiac electrophysiology laboratory and related techniques.

Transcatheter radiofrequency ablation has been widely introduced for the treatment of tachyarrhythmias. The demand for catheter ablation continues to grow rapidly as the level of recommendation for catheter ablation. Traditional catheter ablation is performed under the guidance of X-rays. X-rays can help display the heart contour and catheter position, but the radiobiological effects caused by ionizing radiation and the occupational injuries worn caused by medical staff wearing heavy protective equipment cannot be ignored. Three-dimensional mapping system and intracardiac echocardiography can provide detailed anatomical and electrical information during cardiac electrophysiological study and ablation procedure, and can also greatly reduce or avoid the use of X-rays. In recent years, fluoroless catheter ablation technique has been well demonstrated for most arrhythmic diseases. Several centers have reported performing procedures in a purposefully designed fluoroless electrophysiology catheterization laboratory (EP Lab) without fixed digital subtraction angiography equipment. In view of the lack of relevant standardized configurations and operating procedures, this expert task force has written this consensus statement in combination with relevant research and experience from China and abroad, with the aim of providing guidance for hospitals (institutions) and physicians intending to build a fluoroless cardiac EP Lab, implement relevant technologies, promote the standardized construction of the fluoroless cardiac EP Lab.

Clinical Manifestations, Outcomes, and Mortality Risk Factors of Atrial-Esophageal Fistula: A Systematic Review.

INTRODUCTION: Atrial-esophageal fistula (AEF) is a rare but life-threatening complication of catheter ablation. The clinical presentation and mortality risk factors of AEF have not been fully elucidated. The aim of this study was to systematically review the clinical characteristics and prognosis of AEF. METHODS: PubMed was searched from inception to October 2020 following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement protocol. RESULTS: A total of 190 AEF patients were included. The mean age was 59.29 ± 11.67 years, 74.21% occurred in males, and 81.58% underwent radiofrequency ablation. AEF occurred within 30 days after ablation in 80.82% of patients and occurred later in patients presenting with neurological symptoms compared with other symptoms (median of onset time: 27.5 days vs. 16 days, p < 0.001). Clinical presentation included fever (81.58%) and neurological symptoms (80.53%). Chest computed tomography (abnormal rate of 91.24%) was the preferred diagnostic test, followed by magnetic resonance imaging of the brain (abnormal rate of 90.91%). Repeated testing improved diagnostic evaluation sensitivity. Distinctive imaging results included free air in the mediastinum (incidence rate of 81.73%) and air embolism of the brain (incidence rate of 57.53%). The overall mortality was 63.16%, with worse nonsurgical treatment outcomes compared with outcomes of surgical treatment (94.19% vs. 33.71%, p < 0.001). Conservative or stent intervention was an independent risk factor for mortality. Age (adjusted odds ratio, 1.063, p = 0.004), presentation with neurological symptoms (adjusted odds ratio, 5.706, p = 0.017), and presentation with gastrointestinal bleeds (adjusted odds ratio, 3.009, p = 0.045) were also predictors of mortality. CONCLUSIONS: AEF is a fatal ablation complication. AEF can be diagnosed using a combination of a clinical history of ablation, infection, or neurological symptoms and an abnormal chest CT. Our analysis supports that surgical treatment reduces the mortality rate.

The role of alcohol consumption on echocardiographic and electrophysiologic changes in atrial fibrillation.

BACKGROUND: A wealth of evidence suggests that alcohol consumption is a risk factor for atrial fibrillation (AF); however, the mechanisms underlying this association are unclear. This makes it challenging to develop therapeutic strategies in patients with AF attributed to alcohol consumption. PURPOSE: To investigate the echocardiographic and electrophysiologic changes caused by alcohol consumption in patients with AF. METHODS: The study was registered in Chinese Clinical Trial Registry (Registration number ChiCTR2000041575). Data on 134 consecutive non-valvular AF patients who underwent radiofrequency catheter ablation in our center was collected from April 1, 2019 to June 30, 2020. Patients were divided into no-alcohol (72) and alcohol groups [categorized into light (34), moderate (11) and heavy (17) alcohol consumption]. All patients underwent echocardiographic and electrophysiologic examinations for the assessment of left atrial (LA) strain, inter-atrial conduction, intra-atrial conduction, and atrial effective refractory period (ERP). RESULTS: Overall, the mean age was 61 ± 11 years and 87 (65%) were males. Compared with the no-alcohol group, impaired peak LA longitudinal strain, obvious inter-atrial conduction delay and increasing ERP dispersion were observed in the alcohol group. Intra-atrial conduction delay and ERP dispersion increased with increasing amounts of alcohol consumption. CONCLUSION: Alcohol consumption was associated with substantial abnormal echocardiographic and electrophysiologic changes in AF patients. These changes may contribute to the occurrence and progression of AF attributed to alcohol consumption, which may help in the development of new strategies for the prevention and management of AF. However further investigation is required.

Can intracardiac echocardiography completely replace transesophageal echocardiography to guide left atrial appendage closure?-The comparisons of intracardiac echocardiography with transesophageal echocardiography.

Left atrial appendage closure (LAAC) is an effective means of preventing ischemic stroke in patients with nonvalvular atrial fibrillation. Transesophageal echocardiography (TEE) is the primary imaging technique to guide LAAC. Its shortcomings, namely the use of general anesthesia and tracheal intubation, inevitably increase procedural risks. Intracardiac echocardiography (ICE), a novel imaging modality for guiding LAAC, has proven more advantageous over TEE due to use of local anesthesia, shortened procedural time, and reduced radiation exposure. This review highlights the differences between ICE and TEE guided LAAC, aiming to provide a reference for clinical decision-making.

Feasibility and safety of left atrial appendage occlusion guided by procedural fluoroscopy only: A pilot study.

BACKGROUND: Left atrial appendage occlusion (LAAO) is usually performed via the guidance of procedural transesophageal echocardiography (TEE) companied by general anesthesia (GA). OBJECTIVE: To investigate the feasibility and safety of LAAO guided by procedural fluoroscopy only. METHODS: The patients eligible for LAAO were enrolled into the current study and received implantation of either Watchman device or LAmbre device. The procedure was carried out with procedural fluoroscopy only and no companied GA; the position, shape, and leakage of the device were assessed by contrast angiography. TEE was performed after 3-month follow-up to evaluate the thrombosis, and leakage of device. RESULTS: Ninety-seven patients with atrial fibrillation (AF) with either Watchman device (n = 49) or LAmbre device (n = 48) were consecutively enrolled. Watchman device group was of lower CHA2 DS2 -VASc and HAS-BLED scores compared with LAmbre device groups (p < .05); the two groups had similar distributions of other baseline characteristics (p > .05), including procedural success rate (98.0% vs. 97.9%), mean procedure time, mean fluoroscopy time, total radiation dose, contrast medium dose, percentage of peri-device leakage. Pericardial effusions requiring intervention occurred in two of the Watchman group. TEE follow-up found no patient with residual leakage ≥5 mm at 3 months and no device related thrombosis (DRT). During the 22.0 ± 11.1 months follow-up, two patients experienced ischemic stroke. CONCLUSIONS: LAAO with the procedural imaging of fluoroscopy only exhibited the promising results of efficacy and safety. A prospective randomized multicenter study would be required to verify the observations in this study.

A systematic review and meta-analysis to determine the effect of oral anticoagulants on incidence of dementia in patients with atrial fibrillation.

AIMS: To assess the effect of oral anticoagulant (OAC) administration on incidence of dementia in patients with atrial fibrillation (AF) with Systematic review and meta-analysis. METHODS: We systematically searched the electronic databases including Pubmed, Embase, Cochrane library and ClinicalTrails.gov for relevant articles. The primary outcome was the incidence of dementia. The adjusted risk ratio (RR), odds ratio or hazard ratio were extracted and pooled by the random-effects models. Subgroup analysis was performed according to the setting observational window. Risk of bias was assessed using the Newcastle-Ottawa Scale, while publication bias was assessed by the Begg's and Egger's tests. RESULTS: Nine studies were included in this review (2 prospective and 7 retrospective observational studies, including 613,920 patients). The results presented the significant association between OAC therapy and the reduced risk of dementia compared with no treatment (RR [95% CI] = 0.72 [0.60, 0.86], I2  = 97.2%; P = .000). In the subgroup analysis with an observational window, the pooled RR became statistically non-significant (including four studies, RR [95% CI] = 0.75 [0.51, 1.10], I2  = 98.8%; P = .000). There is no significant risk of bias and publication bias. CONCLUSIONS: This study indicated the protective effect of OAC therapy for dementia in patients with AF. However, the results are limited because of high heterogeneity, inconsistent direction of effect in subgroup analysis with an observational window. Further prospective well-designed study is needed with longer follow-up duration in younger patients.

Is Epicardial Adipose Tissue Associated with Atrial Fibrillation Following Cardiac Surgery? A Systematic Review and Meta-Analysis.

BACKGROUND: Although epicardial adipose tissue (EAT) has been proven to be related to atrial fibrillation (AF) and post-ablation AF recurrence, the association between EAT and AF after cardiac surgery (AFACS) remains unclear. OBJECTIVE: This study was a systematic review and meta-analysis that assessed the relationship between EAT and AFACS. METHODS: Electronic databases were systematically searched for "atrial fibrillation" and "epicardial adipose tissue." The analysis was stratified according to the EAT measurement into three meta-analyses as (1) total EAT volume, (2) left atrial (LA)-EAT volume, and (3) EAT thickness. Standardized mean difference (SMD) was estimated using a random effects model. RESULTS: Eight articles with 10 studies (546 patients) were included. The meta-analysis revealed that EAT was higher in those with AFACS irrespective of the EAT measurement (total EAT volume: SMD = 0.56 mL, 95% confidence interval, CI = 0.56-1.10 mL, I2 = 0.90, P = .04; EAT thickness: SMD = 0.85 mm, 95% CI = 0.04-1.65 mm, I2 = 0.90, P = .04; LA-EAT volume: SMD = 0.57 mL, 95% CI = 0.23-0.92 mL, I2 = 0.00, P = .001). CONCLUSION: EAT was higher in patients with AFACS, measured either as volume or thickness.

Forceps through a 14F flexible sheath for safe retrieval of a dislodged left atrial appendage occluder.

The LAmbre occluder (Lifetech Scientific, Shenzhen, China), a new device for left atrial appendage occlusion (LAAO), is increasingly used, but the retrieval procedure for dislodgements has rarely been reported in humans. We herein reported a case of safe retrieval of dislodged LAmbre occluder. The occluder dislodged to the left atrium (LA) at the end of the LAAO procedure. We failed to retrieve the device in the LA using a LASSO catheter and forceps through an 8.5F sheath. After it suddenly flowed into the aortic arch, we successfully retrieved it using the same forceps through a 14F flexible sheath. We also discuss the reasons for device dislodgment and experiences of device retrieval. We think that forceps can be used to retrieve an embolized LAmbre device in the aorta through a 14F flexible sheath.

Transthoracic echocardiography-monitored CO2-insufflation esophageal endoscopy for diagnosis of Atrioesophageal fistula and prevention of iatrogenic air embolism: a case report.

BACKGROUND: Atrioesophageal fistula (AEF) is the most fatal complication associated with catheter ablation for atrial fibrillation and cannot be easily detected when thoracic contrast-enhanced computed tomography (CT) is normal. CASE PRESENTATION: In this report, we described a diagnostic tool for detecting AEF with doubtful chest CT in which we introduced CO2-insufflation esophageal endoscopy with transthoracic echocardiography monitoring. Using this modified esophageal endoscopy, AEF was established due to the presence of both esophageal lesions and bubbles into the left atrium. That way, our patient accepted to be operated in time with good clinical prognosis. CONCLUSIONS: This modified esophageal endoscopy is an alternative tool for early detection of AEF when normal or doubtful CT findings present.

Atrioesophageal fistula post atrial fibrillation ablation: A multicenter study from China.

BACKGROUND AND OBJECTIVE: Atrioesophageal fistula (AEF) is a rare but devastating complication with high mortality post atrial fibrillation (AF) ablation. The purpose of current study was to determine the epidemiology, clinical features, pathogenesis, and management of AEF after AF ablation. METHODS AND RESULTS: Patients with diagnosed AEF were included and retrospectively analyzed according to the registry of 11 centers in China from January 2010 to December 2019. A total of 16 AEF cases were identified from 44 794 patients who received a left atrial ablation procedure (0.035% per procedure). The interval from procedure to clinical onset of AEF averaged 18.3 days (3-39 days). The fever ranked the most common symptom, occurred in 14 of the 16 cases, followed by neurological deficits (n = 11), chest pain (n = 5), and hematemesis (n = 4). Patients undergoing surgical repair had a better prognosis compared to those receiving nonsurgical management ([4 of 8] 50.0% vs [8 of 8] 100%, P < .05) with an overall mortality rate of 75.0%. CONCLUSION: AEF is highly characterized by varied manifestations. Early diagnosis and urgent surgical repair are vital to those patients and associated with improved survival rates.

Successful catheter ablation of atrial fibrillation improves but not reverses the abnormalities of left atrial mechanics and energy loss.

BACKGROUND: Dissipative energy loss (EL), a new index to quantify the inefficient blood flow, has not been explored within left atrium (LA) in patients with atrial fibrillation (AF). We aimed to study the intra-atrial flow and mechanics in patients with AF before and after successful catheter ablation by evaluating EL and LA global longitudinal strain (LAS). METHODS: In our study, there were 53 patients undergoing catheter ablation for AF at baseline (AF group) and 33 age- and sex-matched controls. They were both assessed of LA EL using vector flow mapping (VFM) and of LAS using two-dimensional tracking (2DTT) during systole (sys), early diastole (ed), and atrial contraction phase (ac). Out of 53 patients, 37 patients who sustained sinus rhythm and carried out the echocardiographic examination at 3 and 6 months follow-up were evaluated of change in EL and LAS. The independent predictors of EL during three phases in AF group were performed using stepwise multivariate linear regression analyses. RESULTS: Left atrium EL and LAS among all phases in AF group were significantly lower than controls (all P < 0.01). During follow-up, LASsys and LASac both significantly improved at 3 and 6 months (both P < 0.01), and ELac significantly increased after 6 months (P < 0.05); ELsys, ELed and LASed were no significant change; EL and LAS among all phases were no normalized during follow-up. The independent predictors of EL were: for ELsys, BSA (P = 0.004) and LASac (P = 0.025); for ELed, E (P = 0.001) and A (P = 0.014); for ELac, E/A (P < 0.001). CONCLUSION: Vector flow mapping and 2DTT revealed impaired intra-atrial flow and mechanics. Successful catheter ablation for AF slightly improves but not reverses the aforementioned impairment, indicating the continuous LA dysfunction.

TWEAK/Fn14 mediates atrial-derived HL-1 myocytes hypertrophy via JAK2/STAT3 signalling pathway.

Atrial myocyte hypertrophy is one of the most important substrates in the development of atrial fibrillation (AF). The TWEAK/Fn14 axis is a positive regulator of cardiac hypertrophy in cardiomyopathy. This study therefore investigated the effects of Fn14 on atrial hypertrophy and underlying cellular mechanisms using HL-1 atrial myocytes. In patients with AF, Fn14 protein levels were higher in atrial myocytes from atrial appendages, and expression of TWEAK was increased in peripheral blood mononuclear cells, while TWEAK serum levels were decreased. In vitro, Fn14 expression was up-regulated in response to TWEAK treatment in HL-1 atrial myocytes. TWEAK increased the expression of ANP and Troponin T, and Fn14 knockdown counteracted the effect. Inhibition of JAK2, STAT3 by specific siRNA attenuated TWEAK-induced HL-1 atrial myocytes hypertrophy. In conclusion, TWEAK/Fn14 axis mediates HL-1 atrial myocytes hypertrophy partly through activation of the JAK2/STAT3 pathway.

Interaction between nitric oxide signaling and gap junctions during ischemic preconditioning: Importance of S-nitrosylation vs. protein kinase G activation.

Much effort has been dedicated to exploring the mechanisms of IPC, and the GJ is one of the proposed targets of IPC. Several lines of evidence have indicated that NO affects GJ permeability regulation and expression of connexin isoforms. NO-induced stimulation of the sGC-cGMP pathway and the subsequent PKG activation could lead directly to connexin phosphorylation and GJ coupling modification. Additionally, because NO-induced cardioprotection against I/R injury beyond the cGMP/PKG-dependent pathway has been reported in isolated cardiomyocytes, it has been posited that NO-mediated GJ coupling might be independent from the activation of the NO-induced cGMP/PKG pathway during IPC. S-nitrosylation by NO exerts a major influence in IPC-induced cardioprotection. It has been suggested that NO-mediated cardioprotection during IPC was not dependent on sGC/cGMP/PKG but on SNO signaling. We need more researches to prove that which signaling pathway (S-nitrosylation or protein kinase G activation) is the major one modulating GJ coupling during IPC. The aim of review article is to discuss the possible signaling pathways of NO in regulating GJ during IPC.

Plumbagin Mediates Cardioprotection Against Myocardial Ischemia/Reperfusion Injury Through Nrf-2 Signaling.

BACKGROUND Plumbagin is a potent antioxidant with anti-inflammatory and anti-carcinogenic action. Myocardial ischemia/reperfusion injury results in organ damage through oxidative stress and inflammatory mechanisms. In this study, we analyzed the potential role of plumbagin against myocardial I/R injury in Wistar rats. MATERIAL AND METHODS Oxidative stress was measured through ROS, lipid peroxide content, and antioxidant enzyme activities. The expression of redox signaling and inflammatory proteins was analyzed through Western blotting. Inflammatory cytokine expressions were determined through ELISA. RESULTS Oxidative stress status was reduced by plumbagin by decreasing ROS and lipid peroxide levels in rats with myocardial I/R (MI/R) injury. Plumbagin regulated redox imbalance induced by I/R injury by modulating the transcription factors NF-κB and Nrf-2. Further, downstream targets of NF-κB (COX-2, iNOS) and Nrf-2 (HO-1, NQO1 and GST) expression were significantly downregulated by plumbagin treatment. Pro-inflammatory cytokine expressions were significantly abrogated by plumbagin treatment. CONCLUSIONS This study shows the protective role of plumbagin against myocardial I/R injury by regulating antioxidant and inflammatory mechanisms.

Role of group I metabotropic glutamate receptors, mGluR1/mGluR5, in connexin43 phosphorylation and inhibition of gap junctional intercellular communication in H9c2 cardiomyoblast cells.

Group I metabotropic glutamate receptors, mGluR1 and mGluR5, are associated with sympathetic nerve activity. Sympathetic nerve stimulation exerts a crucial effect on modulating phosphorylation status and distribution of connexin43 (Cx43) in rat heart. Hence, mGluR1 and mGluR5 have an indirect effect on regulating the function of gap junction channels, which is affected by the availability of Cx43 protein. Additionally, it has been demonstrated that mGluR1/5 are present in ventricular myocardium in particular intercalated disks where Cx43 is the principal component of ventricular gap junction channels. We, therefore, hypothesized that mGluR1/5 might regulate Cx43 phosphorylation and gap junctional intercellular communication (GJIC) directly, independent of sympathetic nerve stimulation. After documenting the presence of mGluR1 and mGluR5 in H9c2 cardiomyoblast cells, addition of the selective mGluR1/5 agonist (S)-3,5-dihydroxyphenylglycine hydrate (DHPG) induced Cx43 phosphorylation and GJIC inhibition in both concentration- and time-dependent manner. The effects of DHPG were abolished by the mGluR1 antagonist LY367385 and the specific inhibitor of MEK1, PD98059 which also reduced phosphorylation of extracellular-signal-regulated protein kinase 1/2 (ERK1/2); but not by the mGluR5 antagonist 6-methyl-2-(phenylethynyl) pyridine hydrochloride or the selective inhibitor of protein kinase C (PKC). In conclusion, in H9c2 cardiomyoblast cells mGluR1 increases Cx43 phosphorylation level and suppresses GJIC involving ERK1/2 but not PKC.