Unexpected transient atrioventricular block and slow junctional rhythm using pulsed field ablation for slow pathway modification: excited or cautious for ablators.

BACKGROUND: Data regarding the effects of pulsed field ablation (PFA) on atrioventricular nodal reentrant tachycardia (AVNRT) are limited. OBJECTIVE: To evaluate the outcomes of PFA for AVNRT, and its impact on dual-pathway electrophysiology. METHODS: A larger cohort of patients with typical AVNRT underwent slow pathway (SP) modification (SPM) using a focal PFA catheter in a biphasic/bipolar manner. The primary endpoints were the efficacy and safety of PFA during the procedure and 6-month follow-up. RESULTS: The acute success of SPM was achieved in all 40 patients. The total ablation time was 7.9±3.8 seconds for 6.4±2.2 ablation sites (ASs). Slow junctional rhythm (SJR) was induced in 32 (80%) patients lasting 28.9±10.3 seconds in 3.0±1.1 ASs per patient. SP was located 11.1±1.2 mm from the largest His activation (LHA). At 9 ASs, SJR could be reinduced after an increase of contact force (CF) from 1.3±0.5g to 6.4±1.3g (P<0.0001). Transient atrioventricular block (AVB) was recorded in 7(17.5%) patients (1 second-degree and 6 third-degree AVB) lasting 435.3±227.4 seconds, with a shorter AS-LHA distance than patients without AVB (7.7±0.6 mm vs. 11.3±1 mm, P<0.0001). PFA-related delayed atrial-His (n=6) and His-atrial (n=1) conduction preceded transient AVB with a constant His-ventricular interval. Normal PR interval was restored within 24 hours. All patients maintained sinus rhythm without any significant adverse events during 6-month follow-up. CONCLUSION: Despite the high efficiency of PFA for SPM, the notable incidence of transient AVB warranted caution when applying it near the His bundle. SJR frequently occurred during SPM and was dependent on moderate CF.

Sulfiredoxin 1 ameliorates doxorubicin-induced cardiotoxicity by suppressing oxidative stress and inflammation via the Sirt1/NLRP3 pathway.

BACKGROUND: Doxorubicin (DOX) is limited in clinical use due to its cardiotoxic side effects. Oxidative stress and inflammation are pivotal mechanisms underlying doxorubicin-induced cardiotoxicity (DIC). Sulfiredoxin 1 (Srxn1) plays a central role in antioxidant effects. However, the role of Srxn1 in DIC has not yet been fully elucidated. This study aims to explore the effects and underlying mechanisms of Srxn1 on DIC. METHODS: We overexpressed Srxn1 in the myocardium using an adeno-associated virus 9 (AAV9) system, delivered through tail vein injection. C57BL/6 mice received intraperitoneal injections of DOX (4 mg/kg) weekly for four consecutive weeks to establish a mouse model of DIC. We used echocardiography, histopathological, and molecular techniques to elucidate the effects and mechanisms. RESULTS: Our findings demonstrate that overexpression of Srxn1 significantly enhanced cardiac function and mitigated myocardial injury in mice exposed to DOX. Overexpressing Srxn1 attenuated oxidative stress and inflammation induced by DOX. Furthermore, Srxn1 overexpression led to upregulation of sirtuin 1 (Sirt1) expression and inhibited the activation of the NOD-like receptor protein 3 (NLRP3) inflammasome. Notably, the protective effects of Srxn1 were significantly abrogated by the Sirt1 inhibitor EX527. CONCLUSION: The protective effects of Srxn1 against DOX-induced cardiac oxidative stress and inflammation operate by targeting the Sirt1/NLRP3 signaling pathway to alleviate DIC. Srxn1 could be a potential candidate for the treatment of DOX-induced myocardial injury.

Interleukin-5 alleviates cardiac remodelling via the STAT3 pathway in angiotensin II-infused mice.

Interleukin-5 (IL-5) has been reported to be involved in cardiovascular diseases, such as atherosclerosis and cardiac injury. This study aimed to investigate the effects of IL-5 on cardiac remodelling. Mice were infused with angiotensin II (Ang II), and the expression and source of cardiac IL-5 were analysed. The results showed that cardiac IL-5 expression was time- and dose-dependently decreased after Ang II infusion, and was mainly derived from cardiac macrophages. Additionally, IL-5-knockout (IL-5-/-) mice were used to observe the effects of IL-5 knockout on Ang II-induced cardiac remodelling. We found knockout of IL-5 significantly increased the expression of cardiac hypertrophy markers, elevated myocardial cell cross-sectional areas and worsened cardiac dysfunction in Ang II-infused mice. IL-5 deletion also promoted M2 macrophage differentiation and exacerbated cardiac fibrosis. Furthermore, the effects of IL-5 deletion on cardiac remodelling was detected after the STAT3 pathway was inhibited by S31-201. The effects of IL-5 on cardiac remodelling and M2 macrophage differentiation were reversed by S31-201. Finally, the effects of IL-5 on macrophage differentiation and macrophage-related cardiac hypertrophy and fibrosis were analysed in vitro. IL-5 knockout significantly increased the Ang II-induced mRNA expression of cardiac hypertrophy markers in myocardial cells that were co-cultured with macrophages, and this effect was reversed by S31-201. Similar trends in the mRNA levels of fibrosis markers were observed when cardiac fibroblasts and macrophages were co-cultured. In conclusions, IL-5 deficiency promote the differentiation of M2 macrophages by activating the STAT3 pathway, thereby exacerbating cardiac remodelling in Ang II-infused mice. IL-5 may be a potential target for the clinical prevention of cardiac remodelling.

Overexpression of MD1 ameliorates pathological myocardial remodeling in diabetic cardiomyopathy by TLR4/STAT3 signaling pathway.

Diabetic cardiomyopathy (DCM) is characterized by oxidative damage and inflammatory responses. Myeloid differentiation protein 1 (MD1) exhibits antioxidant and anti-inflammatory properties. However, the specific role of MD1 in DCM has yet to be elucidated. This study aims to investigate the role of MD1 in DCM and to elucidate the underlying mechanisms. We utilized a gain-of-function approach to explore the involvement of MD1 in DCM. Diabetes was induced in MD1-transgenic (MD1-TG) mice and their wild-type (WT) counterparts via streptozotocin (STZ) injection. Additionally, a diabetes cell model was established using H9c2 cells exposed to high glucose levels. We conducted comprehensive evaluations, including pathological analyses, echocardiography, electrocardiography, and molecular assessments, to elucidate the underlying mechanisms of MD1 in DCM. Notably, MD1 expression was reduced in the hearts of STZ-induced diabetic mice. Overexpression of MD1 significantly improved cardiac function and markedly inhibited ventricular pathological hypertrophy and fibrosis in these mice. Furthermore, MD1 overexpression resulted in a substantial decrease in myocardial reactive oxygen species (ROS) accumulation, mitigating myocardial oxidative stress and reducing the levels of inflammation-related markers such as IL-1ß, IL-6, and TNF-α. Mechanistically, MD1 overexpression inhibited the activation of the TLR4/STAT3 signaling pathway, as demonstrated in both in vivo and in vitro experiments. The overexpression of MD1 significantly impeded pathological cardiac remodeling and improved cardiac function in STZ-induced diabetic mice. This effect was primarily attributed to a reduction in ROS accumulation and mitigation of myocardial oxidative stress and inflammation, facilitated by the inhibition of the TLR4/STAT3 signaling pathway.

Efficacy and safety of pulsed field ablation for accessory pathways: a pilot study.

AIMS: Radiofrequency ablation is used as a first-line therapy for accessory pathways (APs). However, data regarding the effects of pulsed field ablation (PFA) on APs are limited. We sought to evaluate the acute procedural and 6-month success and safety of PFA in a cohort of patients with APs. METHODS AND RESULTS: A focal contact force-sensing PFA catheter was used for patients with APs. Pulsed field ablation generator generated a bipolar and biphasic waveform (±1000 V) with a duration of 100 ms from the tip of the PFA catheter. A 100% acute procedural success was achieved in 10 conscious patients with APs (7 left anterolateral, 2 left inferolateral, and 1 right posteroseptal APs) including 6 (60%) patients after an initial application. The average total ablation time was 6.3 ± 4.9 s for 4.7 ± 1.8 ablation sites (ASs), including 3.1 ± 2.4 s at targets and 3.2 ± 2.9 s at 3.2 ± 2 bolus ASs. The mean skin-to-skin time was 59.3 ± 15.5 min, and PFA catheter dwell time was 29.4 ± 7.8 min. One patient encountered transient sinus arrest during PFA due to parasympathetic overexcitation. Sinus rhythm was restored in all patients without any significant adverse events during the short-term follow-up. CONCLUSION: Pulsed field ablation of APs was feasible, effective, and safe. Its efficiency was remarkable for its ultrarapid termination of AP conduction. Further studies are warranted to prove whether utilization of PFA with current parameters can extend to manifold AP ablation.

Outcomes of Focal Pulsed Field Ablation for Paroxysmal Supraventricular Tachycardia.

BACKGROUND: Pulsed field ablation (PFA) is primarily used for treatment of atrial fibrillation as it provides better safety and efficacy. However, there are limited data available on the use of PFA for paroxysmal supraventricular tachycardia (PSVT). The study sought to describe the outcomes of PSVT ablation with a novel focal contact force (CF)-sensing PFA. METHODS: In this first-in-human pilot study, a focal CF-sensing PFA catheter was used for mapping and ablation navigated with an electroanatomic mapping system (EAMS). Pulsed field energy was delivered as biphasic/bipolar electrical pulse trains with 2000 V/delivery. CF was controlled from 2 g to 10 g during PFA. RESULTS: Procedural acute success was achieved without general anaesthesia or conscious sedation in all 10 patients, including 7 patients diagnosed with typical atrioventricular nodal re-entrant tachycardias and 3 patients with orthodromic reciprocating tachycardias. Successful target ablation time was 2.0 ± 0.5 seconds per patient, and the acute procedural success at the first single site was achieved in 5 patients. The mean skin-to-skin procedure time was 79.4 ± 15 minutes, PFA catheter dwell time was 50.1 ± 14 minutes, and fluoroscopy time was 6.2 ± 7 minutes. Maintenance of sinus rhythm was observed in all patients within 6-month follow-up. No serious adverse events occurred in any subjects during PFA or during the 6-month follow-up. CONCLUSIONS: A focal CF-sensing PFA catheter could effectively, rapidly, and safely ablate PSVT in conscious patients. CLINICAL TRIAL REGISTRATION: NCT05770921.

Crocin alleviates neurotoxicity induced by bupivacaine in SH-SY5Y cells with inhibition of PI3K/AKT signaling.

BACKGROUND: Bupivacaine, a common local anesthetic, can cause neurotoxicity and permanent neurological disorders. Crocin has been widely reported as a potential neuroprotective agent in neural injury models. OBJECTIVE: The aim of this study was to investigate the role and regulatory mechanism of crocin underlying bupivacaine-induced neurotoxicity. METHOD: Human neuroblastoma SH-SY5Y cells were treated with bupivacaine and/or crocin for 24 h, followed by detecting cell viability using 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay. The effect of crocin or bupivacaine on SH-SY5Y cell proliferation was measured by Ki67 immunofluorescence assay. The levels of apoptosis-related proteins and the markers in the PI3K/Akt signaling pathway were examined using western blot analysis. The activities of caspase 3, catalase (CAT), superoxide dismutase (SOD), malondialdehyde (MDA) and glutathione peroxidase (GSH-Px) were tested using respective commercial assay kits. Flow cytometry analysis was executed for detecting SH-SY5Y cell apoptosis. RESULT: Crocin attenuated bupivacaine-induced neurotoxicity in SH-SY5Y cells. Meanwhile, crocin inhibited SH-SY5Y cell apoptosis induced by bupivacaine via repressing the activity of caspase-3, reducing Bax expression, and elevating Bcl-2 expression. Moreover, crocin mitigated oxidative stress in SH-SY5Y cells by increasing the content of CAT, SOD, GSH-Px and reducing the content of MDA. Additionally, crocin protected against bupivacaine-induced dephosphorylation of Akt and GSK-3ß. The protective effects of crocin against bupivacaine-induced neurotoxicity in SH-SY5Y cells were counteracted by the Akt inhibitor. CONCLUSION: These results suggested that crocin may exert a neuroprotective function by promoting cell proliferation and suppressing apoptosis and oxidative stress in SH-SY5Y cells. Thus, crocin might become a promising drug for the treatment of bupivacaine-induced neurotoxicity.

MOTS-c Peptide Attenuated Diabetic Cardiomyopathy in STZ-Induced Type 1 Diabetic Mouse Model.

BACKGROUND: Diabetic cardiomyopathy (DCM) pathogenesis is a common complication of diabetes, but effective treatments remain limited. Mitochondrial-derived peptide MOTS-c has shown therapeutic promise in animal models of various heart diseases, but its efficacy in DCM is unknown. This study investigates the effects of MOTS-c treatment in a mouse model of type 1 diabetes-induced DCM. METHODS: Type 1 diabetes (T1DM) was induced in mice by streptozotocin (STZ) injection. After diabetes establishment, the mice were randomly dividend into two groups treated with or without MOTS-c peptide, which was administered subcutaneously by osmotic pump for 12 weeks. At the end of the experiment, cardiac function, histology, and molecular changes were determined. RESULTS: The results showed that diabetic mice exhibited significant cardiac dysfunction, dilatation, and adverse cardiac remodeling. MOTS-c treatment markedly ameliorated these diabetes-associated myocardial function and structure abnormalities. Additionally, MOTS-c reversed AMPK signaling deactivation and inhibited inflammation in the diabetic heart. CONCLUSIONS: Our data demonstrated a protective effect of MOTS-c against diabetic cardiomyopathy potentially by activating the AMPK pathway and inhibiting inflammation. These findings demonstrate the therapeutic efficacy of MOTS-c for diabetic cardiomyopathy and warrant further investigation into its clinical potential.

Two severe complications post-percutaneous intramyocardial septal radiofrequency ablation in a patient with failed alcohol septal ablation: pulseless electrical activity cardiac arrest and pericardial tamponade-a case report.

Background: Alcohol septal ablation (ASA) can be recommended for patients with drug-refractory hypertrophic obstructive cardiomyopathy (HOCM). Recently, percutaneous intramyocardial septal radiofrequency ablation (PIMSRA) was reported as a safe and effective treatment for HOCM. Case summary: We present a case report of pulseless electrical activity (PEA), cardiac arrest, and pericardial tamponade occurring post-PIMSRA. We performed PIMSRA for the patient with HOCM after failed ASA. Two hours post-PIMSRA, transthoracic echocardiography (TTE) revealed that the hypokinetic basal intraventricular septal (IVS) thickness increased with aggravation of systolic anterior motion of the mitral valve. After the occurrence of subsequent PEA cardiac arrest, veno-arterial extracorporeal membrane oxygenation (VA-ECMO) support was provided. With sinus rhythm restoration and blood pressure stabilization after ECMO removal, the patient had pericardial tamponade on Day 3 post-PIMSRA. After excluding apparent myocardial perforation and draining haemorrhagic effusion under TTE guidance, her symptoms and haemodynamic status improved. She was asymptomatic at her one-year follow-up. The left ventricular outflow tract gradient (LVOTG) at rest and the thickness of the basal IVS reduced to 5 mmHg and 12 mm, respectively. Discussion: We assumed that the main causes of PEA cardiac arrest and pericardial tamponade in our case were ablation-related tissue oedema at the basal IVS and blood leakage possibly related to puncture haemorrhage, respectively. While waiting for myocardial oedema to resolve, ECMO was applied as a bridge-to-recovery therapeutic approach. Pericardiocentesis is a strategy for the emergency drainage of pericardial effusion. It is essential to distinguish life-threatening complications with TTE for management planning post-PIMSRA.

The impact of empirical Marshall vein ethanol infusion as a first-choice intraoperative strategy on the long-term outcomes in patients with persistent atrial fibrillation undergoing mitral isthmus ablation.

Background: Marshall vein ethanol infusion (MVEI) as an additional therapy to conventional catheter ablation (CA) has been proved to be efficacious in patients with persistent atrial fibrillation (PeAF). However, whether empirical MVEI could be the first-line strategy in mitral isthmus (MI) ablation has seldom been investigated. Here, we aim to compare the efficacy, safety, and long-term outcomes between provisional and empirical MVEI in PeAF patients undergoing the index MI ablation procedure. Methods: We enrolled 133 patients with PeAF either in the provisional group (n = 38, MVEI was performed when conventional endocardial and/or epicardial ablation procedures were inadequate to achieve bidirectional MI block) or in the empirical group (n = 95, MVEI was performed empirically before MI CA). Results: All of the baseline characteristics were comparable. Less spontaneous or inducible atrial tachycardias (ATs) were encountered in the empirical group of patients (P < 0.001). More epicardial ablations were applied (26.3% vs. 9.5%, P = 0.016) and a higher incidence of CA-facilitated restoration of sinus rhythm was recorded (86.8% vs. 11.7%, P < 0.001) in the provisional group of patients. Although more fluoroscopy time (6.4[4.2, 9.3] vs. 9.5[5.9, 11.6] min, P = 0.019) and radiation exposure (69.0[25.3, 160.2] vs. 122.0[62.5, 234.1] mGy, P = 0.010) were documented in the empirical group with comparable procedure time, less time (455.9 ± 192.2 vs. 366.5 ± 161.3 s, P = 0.038) was consumed to achieve bidirectional MI block during endocardial ablation in the provisional group. Incidences of procedure-related complications were similar between the two groups. During a 16.5 ± 4.4-month follow-up, the empirical group of patients showed a significantly higher rate of freedom from AT recurrence (95.8% vs. 81.6%, log-rank P = 0.003), while the rate of freedom from AF or atrial tachyarrhythmias (combining AF and AT) was similar. Both univariate (HR 0.19, 95% CI 0.05-0.64, P = 0.008) and multivariate (HR 0.25, 95% CI 0.07-0.92, P = 0.037) Cox regression analyses indicated that empirical MVEI was independently associated with lower long-term AT recurrence. Conclusion: Among patients with PeAF who underwent the index MI ablation procedure, empirical MVEI could reduce endocardial MI ablation time and provide greater long-term freedom from AT recurrence.

Visfatin aggravates transverse aortic constriction-induced cardiac remodelling by enhancing macrophage-mediated oxidative stress in mice.

Previous studies have reported that visfatin can regulate macrophage polarisation, which has been demonstrated to participate in cardiac remodelling. The aims of this study were to investigate whether visfatin participates in transverse aortic constriction (TAC)-induced cardiac remodelling by regulating macrophage polarisation. First, TAC surgery and angiotensin II (Ang II) infusion were used to establish a mouse cardiac remodelling model, visfatin expression was measured, and the results showed that TAC surgery or Ang II infusion increased visfatin expression in the serum and heart in mice, and phenylephrine or hydrogen peroxide promoted the release of visfatin from macrophages in vitro. All these effects were dose-dependently reduced by superoxide dismutase. Second, visfatin was administered to TAC mice to observe the effects of visfatin on cardiac remodelling. We found that visfatin increased the cross-sectional area of cardiomyocytes, aggravated cardiac fibrosis, exacerbated cardiac dysfunction, further regulated macrophage polarisation and aggravated oxidative stress in TAC mice. Finally, macrophages were depleted in TAC mice to investigate whether macrophages mediate the regulatory effect of visfatin on cardiac remodelling, and the results showed that the aggravating effects of visfatin on oxidative stress and cardiac remodelling were abrogated. Our study suggests that visfatin enhances cardiac remodelling by promoting macrophage polarisation and enhancing oxidative stress. Visfatin may be a potential target for the prevention and treatment of clinical cardiac remodelling.

CTRP5 Attenuates Doxorubicin-Induced Cardiotoxicity Via Inhibiting TLR4/NLRP3 Signaling.

BACKGROUND: C1q/tumor necrosis factor-related protein 5 (CTRP5) has been reported to be a crucial regulator in cardiac ischemia/reperfusion (I/R) injury. Nevertheless, the potential role of CTRP5 in doxorubicin (DOX)-induced cardiotoxicity and the potential mechanisms remain largely unclear. METHODS: We overexpressed CTRP5 in the hearts using an adeno-associated virus 9 (AAV9) system through tail vein injection. C57BL/6 mice were subjected to DOX (15 mg/kg/day, i.p.) to generate DOX-induced cardiotoxicity for 4 weeks. Subsequently, cardiac staining and molecular biological analysis were performed to analyze the morphological and biochemical effects of CTRP5 on the cardiac injury. H9c2 cells were used for validation in vitro. RESULTS: CTRP5 expression was down-regulated after DOX treatment both in vivo and in vitro. CTRP5 overexpression significantly attenuated DOX-induced cardiac injury, cardiac dysfunction, inhibited oxidative stress and inflammatory response. Mechanistically, CTRP5 overexpression markedly decreased the protein expression of toll-like receptor 4 (TLR4), NLRP3, cleaved caspase-1 and caspase-1, indicating TLR/NLRP3 signaling contributes to the cardioprotective role of CTRP5 in DOX-induced cardiotoxicity. CONCLUSIONS: Together, our findings demonstrated that CTRP5 overexpression could protect the heart from oxidative stress and inflammatory injury induced by DOX through inhibiting TLR4/NLRP3 signaling, suggesting that CTRP5 might be a potential therapeutic target in the prevention of DOX-induced cardiotoxicity.

Antiresistin Neutralizing Antibody Alleviates Doxorubicin-Induced Cardiac Injury in Mice.

Background: Resistin is closely related to cardiovascular diseases, and this study is aimed at examining the role of resistin in doxorubicin- (DOX-) induced cardiac injury. Methods: First, 48 mice were divided into 2 groups and treated with saline or DOX, and the expression of resistin at different time points was examined (N = 24). A total of 40 mice were pretreated with the antiresistin neutralizing antibody (nAb) or isotype IgG for 1 hour and further administered DOX or saline for 5 days. The mice were divided into 4 groups: saline-IgG, saline-nAb, DOX-IgG, and DOX-nAb (N = 10). Cardiac injury, cardiomyocyte apoptosis, inflammatory factors, and the biomarkers of M1 and M2 macrophages in each group were analyzed. Result: DOX administration increased the expression of resistin. DOX treatment exacerbated the loss of body and heart weight and cardiac vacuolation in mice. The antiresistin nAb reversed these conditions, downregulated the expression of myocardial injury markers, and decreased apoptosis. In addition, the antiresistin nAb decreased p65 pathway activation, decreased M1 macrophage differentiation and the expression of related inflammatory factors, and increased M2 macrophage differentiation and the expression of related inflammatory factors. Conclusion: The antiresistin nAb protected against DOX-induced cardiac injury by reducing cardiac inflammation and may be a promising target to relieve DOX-related cardiac injury.

Visfatin Amplifies Cardiac Inflammation and Aggravates Cardiac Injury via the NF-κB p65 Signaling Pathway in LPS-Treated Mice.

Background: Visfatin is an adipocytokine that has been demonstrated to be involved in cardiovascular diseases. This study aims at determining the role of visfatin in sepsis-induced cardiac injury and identify its possible mechanisms. Methods: Dynamic changes in visfatin expression in mice with lipopolysaccharide- (LPS-) induced septicemia were measured. Additionally, mice were pretreated with visfatin and further administered LPS to observe the effects of visfatin on cardiac injury. Finally, septic mice were also pretreated with JSH-23 to investigate whether visfatin regulates cardiac injury via the NF-κB p65 pathway. Results: Visfatin expression levels in both the heart and serum were increased in LPS-treated mice and peaked at 6 hours, and visfatin was derived from cardiac macrophages. In septic mice, pretreatment with visfatin reduced the survival rate, worsened cardiac dysfunction, and increased the expression of cardiac injury markers, including creatine kinase myocardial bound (CK-MB) and lactate dehydrogenase (LDH). Treatment with visfatin also increased the infiltration of CD3+ cells and F4/80+ cells, amplified the cardiac inflammatory response, and elevated myocardial cell apoptosis. Treatment with JSH-23 reversed the effects of visfatin in septic mice. Conclusions: This study showed that visfatin amplifies the cardiac inflammatory response and aggravates cardiac injury through the p65 signaling pathway. Visfatin may be a clinical target for preventing cardiac injury in sepsis.

Mitochondrial derived peptide MOTS-c prevents the development of heart failure under pressure overload conditions in mice.

MOTS-c, a mitochondrial-derived peptide (MDP), has been shown to have multiple biological activities such as antioxidation, anti-inflammation, and anti-apoptosis properties. In the present study, we aimed at evaluating the therapeutic effect of MOTS-c peptide in an animal model of heart failure. The heart failure mouse model was made by transverse aortic constriction (TAC) operations. The MOTS-c peptide was administrated subcutaneously by using an osmotic pump. At the end of the animal experiment, cardiac function was evaluated by echocardiography, and heart tissues were subjected to histological and molecular analysis. In vitro cultured H9C2 cells were used to test the effects of MOTS-c overexpression on cell death in response to H2 O2 stimulation. Our study showed that MOTS-c peptide attenuated TAC-induced cardiac dysfunction and remodelling. In addition, the MOTS-c peptide reduced the inflammatory response and upregulated the antioxidant capacity, coupled with the activation of the AMPK pathway in the heart of the TAC mouse model. In in vitro cultured cardiac cells, overexpression of MOTS-c was shown to activate the AMPK pathway and protect cell apoptosis in response to H2 O2 stimulation. Taken together, our study suggested that MOTS-c peptides may have therapeutic potential in treating HF.

Downregulation of CIRP Prone Cells to Oxidative Injury via Regulating Nrf2 Signaling Pathway.

Cold-inducible RNA-binding protein (CIRP) is a cellular stress-response protein, whose expression can be induced by a variety of stress conditions. Our previous study showed that intracellular CIRP is a protective factor against cellular oxidative stress and silencing of CIRP gene prone cells to apoptosis. However, the underlying mechanism remains unknown. The present study was aimed at investigating the possible mechanisms underlying the protective role of CIRP in oxidative stress injury. Herein, we used HEK293T cells as our cell model to investigate the relation between CIRP and the possible antioxidant pathways by using the latest genetic silencing technologies. Our results showed that silencing CIRP by using SaiRNA-based genetic silencing tool leads to the downregulation of Nrf2 and Nrf2-regulated antioxidant genes in HEK293T cells. Taken together, our study identified the antioxidant Nrf2 signaling pathway as a downstream target of CIRP, and silencing CIRP may prone cells to apoptosis by downregulating the Nrf2 antioxidant pathway in response to oxidative injury.

Gab1 Overexpression Alleviates Doxorubicin-Induced Cardiac Oxidative Stress, Inflammation, and Apoptosis Through PI3K/Akt Signaling Pathway.

ABSTRACT: Grb2-associated binding protein 1 (Gab1), an intracellular scaffolding adaptor, was involved in several cardiovascular diseases. However, the role of Gab1 in doxorubicin (DOX)-induced cardiotoxicity remains largely unknown. The present study investigated whether Gab1 protected against DOX-induced cardiotoxicity and the underlying mechanism. We overexpressed Gab1 in the hearts using an adeno-associated virus 9 system through tail vein injection. C57BL/6 mice were subjected to DOX (15 mg/kg/d, i.p.) to generate DOX-induced cardiotoxicity. Echocardiography, histological analysis, immunofluorescence and enzyme-linked immunosorbent assay (ELISA) kits, Western blotting, and quantitative real-time polymerase chain reaction (PCR) evaluated DOX-induced cardiotoxicity and the underlying mechanisms. Myocardial Gab1 protein and messenger RNA (mRNA) levels were markedly decreased in DOX-administered mice. Overexpression of Gab1 in myocardium significantly improved cardiac function and attenuated cardiac oxidative stress, inflammatory response, and apoptosis induced by DOX. Mechanistically, we found that PI3K/Akt signaling pathway was downregulated after DOX treatment, and Gab1 overexpression activated PI3K/Akt signaling pathway, whereas PI3K/Akt signaling pathway inhibition abolished the beneficial effect of Gab1 overexpression in the heart. Collectively, our results indicated that Gab1 is essential for cardioprotection against DOX-induced oxidative stress, inflammatory response, and apoptosis by mediating PI3K/Akt signaling pathway. And cardiac gene therapy with Gab1 provides a novel therapeutic strategy against DOX-induced cardiotoxicity.

Anti-fibrotic mechanism of SPP1 knockdown in atrial fibrosis associates with inhibited mitochondrial DNA damage and TGF-ß/SREBP2/PCSK9 signaling.

Atrial fibrosis occurs frequently with structural heart disease and is considered as a major cause of arrhythmia. Microarray-based profiling predicted the differential expression of SPP1 in atrial fibrosis. Herein, we aimed to analyze the role of shRNA-mediated SPP1 knockdown in the progression of atrial fibrosis as well as the downstream mechanism. In vivo model in mice and in vitro HL-1 cell model of atrial fibrosis were developed by the angiotensin II (Ang II) method, where SPP1 expression was validated by RT-qPCR. Gain- and loss-of-function experiments were performed in Ang II-induced mice and HL-1 cells to evaluate the effect of the SPP1/TGF-ß/SREBP2/PCSK9 axis on cell viability, apoptosis, collagen production and mitochondrial DNA (mtDNA) damage in atrial fibrosis. Expression of SPP1, TGF-ß, SREBP2 and PCSK9 was increased in Ang II-induced mice and HL-1 cells. Silencing of SPP1 inhibited the occurrence of atrial fibrosis, as reflected by attenuated cell viability and collagen production as well as increased cell apoptosis. Conversely, upregulated SPP1 enhanced atrial fibrosis, which was related to upregulation of TGF-ß. In addition, TGF-ß elevated the expression of SREBP2, which promoted mtDNA damage and the consequent atrial fibrosis by augmenting the expression of PCSK9. This study uncovers previously unrecognized pro-fibrotic activities of SPP1 in atrial fibrosis, which is achieved through activation of the TGF-ß/SREBP2/PCSK9 signaling pathway and promotion of mtDNA damage.