T-2 toxin induces cardiac fibrosis by causing metabolic disorders and up-regulating Sirt3/FoxO3α/MnSOD signaling pathway-mediated oxidative stress.

T-2 toxin, an omnipresent environmental contaminant, poses a serious risk to the health of humans and animals due to its pronounced cardiotoxicity. This study aimed to elucidate the molecular mechanism of cardiac tissue damage by T-2 toxin. Twenty-four male Sprague-Dawley rats were orally administered T-2 toxin through gavage for 12 weeks at the dose of 0, 10, and 100 nanograms per gram body weight per day (ng/(g·day)), respectively. Morphological, pathological, and ultrastructural alterations in cardiac tissue were meticulously examined. Non-targeted metabolomics analysis was employed to analyze alterations in cardiac metabolites. The expression of the Sirt3/FoxO3α/MnSOD signaling pathway and the level of oxidative stress markers were detected. The results showed that exposure to T-2 toxin elicited myocardial tissue disorders, interstitial hemorrhage, capillary dilation, and fibrotic damage. Mitochondria were markedly impaired, including swelling, fusion, matrix degradation, and membrane damage. Metabonomics analysis unveiled that T-2 toxin could cause alterations in cardiac metabolic profiles as well as in the Sirt3/FoxO3α/MnSOD signaling pathway. T-2 toxin could inhibit the expressions of the signaling pathway and elevate the level of oxidative stress. In conclusion, the T-2 toxin probably induces cardiac fibrotic impairment by affecting amino acid and choline metabolism as well as up-regulating oxidative stress mediated by the Sirt3/FoxO3α/MnSOD signaling pathway. This study is expected to provide targets for preventing and treating T-2 toxin-induced cardiac fibrotic injury.

Corilagin Alleviates Ang II-Induced Cardiac Fibrosis by Regulating the PTEN/AKT/mTOR Pathway.

This research aimed to evaluate the therapeutic effect of corilagin (Cor) against angiotensin II (Ang II)-induced cardiac fibrosis and its underlying mechanisms. C57BL/6 mice (male, 8-10 weeks) received saline or Ang II (2.0 mg/kg/day) via subcutaneous infusion and intraperitoneal injection of Cor (30 mg/kg) for 28 days. Ang II induction increased the fibrotic area, whereas Cor treatment inhibited the fibrotic area significantly. Cor markedly reduced the Ang II-induced cardiac fibroblasts. Cor significantly inhibited Ang II-induced increase in expressions of smooth muscle alpha-actin (α-SMA), collagen I, collagen III, transforming growth factor beta 1 (TGF-ß1), fibronectin, and connective tissue growth factor (CTGF). Cor suppressed the intracellular reactive oxygen species (ROS) production. Cor therapy reduced Ang II-induced malondialdehyde (MDA) content, whereas superoxide dismutase (SOD) and catalase (CAT) activities were increased (all, P < .001). Moreover, Ang II induction elevated the expression of phosphorylated phosphatase and tensin homolog (p-PTEN), phosphorylated protein kinase B (p-AKT) (Ser473) and phosphorylated mammalian target of rapamycin (p-mTOR) (Ser 2448), whereas Cor reduced their expressions. Cor treatment inhibited the migration ability of the cardiac fibroblast, whereas a PTEN inhibitor, VO-ohpic, increased the migration capability. Cor could have a protective effect against Ang II-induced cardiac fibrosis via inhibition of the PTEN/AKT/mTOR pathway.

Matairesinol blunts adverse cardiac remodeling and heart failure induced by pressure overload by regulating Prdx1 and PI3K/AKT/FOXO1 signaling.

BACKGROUND: Pathological cardiac remodeling is a critical process leading to heart failure, characterized primarily by inflammation and apoptosis. Matairesinol (Mat), a key chemical component of Podocarpus macrophyllus resin, exhibits a wide range of pharmacological activities, including anti-hydatid, antioxidant, antitumor, and anti-inflammatory effects. PURPOSE: This study aims to investigate whether Matairesinol alleviate cardiac hypertrophy and remodeling caused by pressure overload and to elucidate its mechanism of action. METHODS: An in vitro pressure loading model was established using neonatal rat cardiomyocytes treated with angiotensin Ⅱ, while an in vivo model was created using C57 mice subjected to transverse aortic constriction (TAC). To activate the PI3K/Akt/FoxO1 pathway, Ys-49 was employed. Moreover, small interfering RNA (siRNA) and short hairpin RNA (shRNA) were utilized to silence Prdx1 expression both in vitro and in vivo. Various techniques, including echocardiography, wheat germ agglutinin (WGA) staining, HE staining, PSR staining, and Masson trichrome staining, were used to assess cardiac function, cardiomyocyte cross-sectional area, and fibrosis levels in rats. Apoptosis in myocardial tissue and in vitro was detected by TUNEL assay, while reactive oxygen species (ROS) content in tissues and cells was measured using DHE staining. Furthermore, the affinity of Prdx1 with Mat and PI3K was analyzed using computer-simulated molecular docking. Western blotting and RT-PCR were utilized to evaluate Prdx1 levels and proteins related to apoptosis and oxidative stress, as well as the mRNA levels of cardiac hypertrophy and fibrosis-related indicators. RESULTS: Mat significantly alleviated cardiac hypertrophy and fibrosis induced by TAC, preserved cardiac function, and markedly reduced cardiomyocyte apoptosis and oxidative damage. In vitro, mat attenuated ang Ⅱ - induced hypertrophy of nrvms and activation of neonatal rat fibroblasts. Notably, activation of the PI3K/Akt/FoxO1 pathway and downregulation of Prdx1 expression were observed in TAC mice; however, these effects were reversed by Mat treatment. Furthermore, Prdx1 knockdown activated the PI3K/Akt/FoxO1 pathway, leading to exacerbation of the disease. Molecular docking indicated that Molecular docking indicated that Mat upregulated Prdx1 expression by binding to it, thereby inhibiting the PI3K/Akt/FoxO1 pathway and protecting the heart by restoring Prdx1 expression levels. CONCLUSION: Matairesinol alleviates pressure overload-induced cardiac remodeling both in vivo and in vitro by upregulating Prdx1 expression and inhibiting the PI3K/Akt/FoxO1 pathway. This study highlights the therapeutic potential of Matairesinol in the treatment of cardiac hypertrophy and remodeling, providing a promising avenue for future research and clinical application.

Serotonin transporter deficiency in mice results in an increased susceptibility to HTR2B-dependent pro-fibrotic mechanisms in the cardiac valves and left ventricular myocardium.

Increased serotonin (5HT) concentration and signaling, can lead to pathological remodeling of the cardiac valves. We previously showed that a reduction of the 5HT transporter (SERT) expression in the mitral valve (MV) contributes to the progression of degenerative MV regurgitation (MR). We sought to investigate the myocardial and valvular phenotype of SERT-/- mice in order to identify remodeling mechanisms specific to the MV and left ventricular (LV) remodeling. Using 8- and 16-week-old WT and SERT-/- mice we show that male and female animals deficient of SERT have pathological remodeling of the cardiac valves, myocardial fibrosis, diminished ejection fraction and altered left ventricular dimensions. In the MV and intervalvular area of the aortic valve (AV)-MV, gene expression, including Col1a1 mRNA, was progressively altered with age up until 16 weeks of age. In contrast, in the AV and myocardium, most gene expression changes occurred earlier and plateaued by 8 weeks. To explore basal differences in susceptibility to remodeling stimuli among cardiac valves, valve interstitial cells (VIC) were isolated from AV, MV, tricuspid valve (TV), pulmonary valve (PV) and fibroblasts (Fb) from the myocardial apex from 16 weeks old wild type (WT) mice. After 24h stimulation with 10µM of 5HT, the gene expression of Col1a1 and Acta2 were upregulated in MVIC to a higher degree than in VIC from other valves and Fb. Treatment with TGFß1 similarly upregulated Cola1 and Acta2 in MVIC and AVIC, while the increase was milder in right heart VIC and Fb. Experiments were also carried out with human VIC. In comparison to mice, human left heart VIC were more sensitive to 5HT and TGFß1, upregulating COL1A1 and ACTA2; TGFß1 upregulated HTR2B expression in all VIC. Our results support the hypothesis that a deleterious cardiac effect of SERT downregulation may be mediated by increased susceptibility to HTR2B-dependent pro-fibrotic mechanisms, which are distinct among VIC populations and cardiac fibroblasts, regardless of SERT activity. Given that HTR2B mechanisms involved in VIC and myocardial remodeling response are due to both 5HT and also to downstream related TGFß1 and TNFα activity, targeting HTR2B could be a therapeutic strategy for dual treatment of MR and LV remodeling.

Exogenous ECM in an environmentally-mediated in vitro model for cardiac fibrosis.

Few clinical solutions exist for cardiac fibrosis, creating the need for a tunable in vitro model to better understand fibrotic disease mechanisms and screen potential therapeutic compounds. Here, we combined cardiomyocytes, cardiac fibroblasts, and exogenous extracellular matrix (ECM) proteins to create an environmentally-mediated in vitro cardiac fibrosis model. Cells and ECM were combined into 2 types of cardiac tissues- aggregates and tissue rings. The addition of collagen I had a drastic negative impact on aggregate formation, but ring formation was not as drastically affected. In both tissue types, collagen and other ECM did not severely affect contractile function. Histological analysis showed direct incorporation of collagen into tissues, indicating that we can directly modulate the cells' ECM environment. This modulation affects tissue formation and distribution of cells, indicating that this model provides a useful platform for understanding how cells respond to changes in their extracellular environment and for potential therapeutic screening.

Hyperactivation of ATF4/TGF-ß1 signaling contributes to the progressive cardiac fibrosis in Arrhythmogenic cardiomyopathy caused by DSG2 Variant.

BACKGROUND: Arrhythmogenic cardiomyopathy (ACM) is an inherited cardiomyopathy characterized with progressive cardiac fibrosis and heart failure. However, the exact mechanism driving the progression of cardiac fibrosis and heart failure in ACM remains elusive. This study aims to investigate the underlying mechanisms of progressive cardiac fibrosis in ACM caused by newly identified Desmoglein-2 (DSG2) variation. METHODS: We identified homozygous DSG2F531C variant in a family with 8 ACM patients using whole-exome sequencing and generated Dsg2F536C knock-in mice. Neonatal and adult mouse ventricular myocytes isolated from Dsg2F536C knock-in mice were used. We performed functional, transcriptomic and mass spectrometry analyses to evaluate the mechanisms of ACM caused by DSG2F531C variant. RESULTS: All eight patients with ACM were homozygous for DSG2F531C variant. Dsg2F536C/F536C mice displayed cardiac enlargement, dysfunction, and progressive cardiac fibrosis in both ventricles. Mechanistic investigations revealed that the variant DSG2-F536C protein underwent misfolding, leading to its recognition by BiP within the endoplasmic reticulum, which triggered endoplasmic reticulum stress, activated the PERK-ATF4 signaling pathway and increased ATF4 levels in cardiomyocytes. Increased ATF4 facilitated the expression of TGF-ß1 in cardiomyocytes, thereby activating cardiac fibroblasts through paracrine signaling and ultimately promoting cardiac fibrosis in Dsg2F536C/F536C mice. Notably, inhibition of the PERK-ATF4 signaling attenuated progressive cardiac fibrosis and cardiac systolic dysfunction in Dsg2F536C/F536C mice. CONCLUSIONS: Hyperactivation of the ATF4/TGF-ß1 signaling in cardiomyocytes emerges as a novel mechanism underlying progressive cardiac fibrosis in ACM. Targeting the ATF4/TGF-ß1 signaling may be a novel therapeutic target for managing ACM.

Histone deacetylase 6 controls cardiac fibrosis and remodelling through the modulation of TGF-ß1/Smad2/3 signalling in post-infarction mice.

Histone deacetylase 6 (HDAC6) belongs to the class IIb group of the histone deacetylase family, which participates in remodelling of various tissues. Herein, we sought to examine the potential regulation of HDAC6 in cardiac remodelling post-infarction. Experimental myocardial infarction (MI) was created in HDAC6-deficient (HDAC6-/-) mice and wild-type (HADC6+/+) by left coronary artery ligation. At days 0 and 14 post-MI, we evaluated cardiac function, morphology and molecular endpoints of repair and remodelling. At day 14 after surgery, the ischemic myocardium had increased levels of HADC6 gene and protein of post-MI mice compared to the non-ischemic myocardium of control mice. As compared with HDAC6-/--MI mice, HADC6 deletion markedly improved infarct size and cardiac fibrosis as well as impaired left ventricular ejection fraction and left ventricular fraction shortening. At the molecular levels, HDAC6-/- resulted in a significant reduction in the levels of the transforming growth factor-beta 1 (TGF-ß1), phosphor-Smad-2/3, collagen I and collagen III proteins and/or in the ischemic cardiac tissues. All of these beneficial effects were reproduced by a pharmacological inhibition of HADC6 in vivo. In vitro, hypoxic stress increased the expressions of HADC6 and collagen I and III gene; these alterations were significantly prevented by the HADC6 silencing and TubA loading. These findings indicated that HADC6 deficiency resists ischemic injury by a reduction of TGF-ß1/Smad2/3 signalling activation, leading to decreased extracellular matrix production, which reduces cardiac fibrosis and dysfunction, providing a potential molecular target in the treatment of patients with MI.

Assessment of ursolic acid effect on in vitro model of cardiac fibrosis.

This study aimed to evaluate the effects of ursolic acid (UA) on Angiotensin II (Ang II)-treated neonatal rat cardiac fibroblasts (rCFs) as an in vitro model of cardiac fibrosis. The rCFs were isolated from two-day-old neonatal rats. An in vitro model of cardiac fibrosis was established using 500 nm Ang II treatment for 48 h. The cells were then treated with 5 and 10 µM of UA for 24 and 48 h. Masson's trichrome staining, hydroxyproline content assay, scratch assay, apoptosis assay, measurements of superoxide dismutase (SOD) and malondialdehyde (MDA) levels, real-time PCR, immunocytology and western blotting, were employed to assess the impact of UA. Ang II induced fibrosis in rCFs, as evidenced by the examination of various fibrotic markers. Upon treatment with 5 and 10 µM of UA, the amount of fibrosis in Ang II-treated rCFs was significantly decreased, so that the hydroxyproline concentration was reduced to 0.3 and 0.7 times, respectively. The RNA expression of the Col1a1, Col3a1, Tgfb1, Acta2 and Mmp2 genes had a decrease as well as Nrf2 and HO-1 had an increase after UA treatment. UA could lessen the harmful effects of cardiac fibrosis in a dose- and time-dependent manner, due to its antiapoptotic, antioxidant and cardioprotective properties. This suggests the potential of UA for treatment of cardiac fibrosis.

Myocardial Fibrosis Quantification Methods by Cardiovascular Magnetic Resonance Imaging in Patients with Fabry Disease.

Background/Objectives: The presence of late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) in patients with Fabry disease (FD) is a predictor of adverse cardiac events. The aim of this study was to establish the most reliable and reproducible technique for quantifying LGE in patients with FD. Methods: Twenty FD patients with LGE who underwent CMR on the same scanner and LGE sequence were included. LGE quantifications were done using gray-scale thresholds of 2, 3, 4, 5 and 6 standard deviations (SD) above the mean signal intensity of the remote myocardium, the full width at half maximum method (FWHM), visual assessment with threshold (VAT) and the fully manual method (MM). Results: The mean amount of fibrosis varied between quantification techniques from 36 ± 19 at 2SD to 2 ± 2 g using the FWHM (p < 0.0001). Intraobserver reliability was excellent for most methods, except for the FWHM which was good (ICC 0.84; all p < 0.05). Interobserver reliability was excellent for VAT (ICC 0.94) and good for other techniques (all p < 0.05). Intraobserver reproducibility showed the lowest coefficient of variation (CV, 6%) at 5SD and at 2SD and VAT (35% and 38%) for interobserver reproducibility. The FWHM revealed the highest CV (63% and 94%) for both intra- and interobserver reproducibility. Conclusions: The available methods for LGE quantification demonstrate good to excellent intra- and interobserver reproducibility in patients with FD. The most reliable and reproducible techniques were VAT and 5SD, whereas the FWHM was the least reliable in the setting of our study. The total amount of LGE varies strongly with the quantification technique used.

Macrophage MKL1 contributes to cardiac fibrosis in a mouse model of myocardial infarction.

AIMS: Cardiac fibrosis is characterized by aberrant collagen deposition in the heart. Macrophage polarization or infiltration is the main reason to accelerate the collagen deposition. We attempted to investigate the involvement of MKL1 in macrophages during the development of cardiac fibrosis. MATERIALS AND METHODS: Cardiac fibrosis is induced by myocardial infarction (MI). The MKL1f/f mice were crossed to the Lyz2-cre mice to generate macrophage conditional MKL1 knockout mice (MKL1ΔMφ). In addition, macrophage conditional MKL1 overexpression mice (MKL1Mϕ-OE) were constructed by crossing Lyz2-cre mice to MKL1ΔN200-Rosa26 mice. KEY FINDINGS: MKL1 expression was significantly increased in macrophages of both ischemic cardiomyopathy (ICM) patients and mice induced to develop myocardial infarction. Deletion of MKL1 in macrophages improved the heart function after MI-induced cardiac fibrosis. Consistently, MKL1Mϕ-OE mice displayed more severe cardiac fibrosis and worsened heart function than the control mice after MI. Moreover, administration of a small-molecule MKL1 inhibitor CCG-1423 also decreased the collagen deposition after MI. SIGNIFICANCE: Our data demonstrate that MKL1 in macrophages contributes to cardiac fibrosis pathogenesis and reinforce the notion that targeting MKL1 may yield effective antifibrotic therapeutics in the heart.

Impact of inhibition of the renin-angiotensin system on early cardiac and renal abnormalities in Sprague Dawley rats fed short-term high fructose plus high salt diet.

Introduction: The combination of a high fructose and high salt diet typical of western diet induces high blood pressure, aortic stiffening, left ventricular (LV) diastolic dysfunction and impaired renal function in rodents. Despite an activated renin-angiotensin system (RAS) in rats fed high fructose and high salt, acute inhibition of the RAS pathway does not improve cardiac and vascular parameters. It may well be that longer term treatment is required to permit remodeling and improve cardiovascular function. Thus, we hypothesized that chronic RAS inhibition fructose+high salt-fed rats to restore blood pressure (BP) to levels similar to glucose plus normal salt-fed controls will improve cardiorenal function and histopathology. Methods: Male and female Sprague Dawley rats monitored by hemodynamic telemetry were fed 0.4% NaCl chow during baseline, then changed to chow containing either 20% glucose+0.4% NaCl (G) or 20% fructose+4% NaCl (F) and treated with vehicle, enalapril (Enal, 4 mg/kg/d) or losartan (Los, 8 mg/kg/d) by osmotic minipump for 25-26 days. Results: BP was elevated in the fructose+high salt groups of both sexes (P < 0.05) and restored to control levels by Enal or Los. Pulse wave velocity (PWV) was lower in female F+Los rats and cardiac output higher in female F+Enal rats. GFR was not changed by diet or treatment. Fructose+high salt groups of both sexes displayed higher albuminuria that was decreased by Enal in male rats. Cardiac fibrosis and mesangial hypercellularity were greater in fructose+high salt-fed rats of both sexes and improved with either Los or Enal. Discussion: Thus, inhibition of the RAS improves early changes in cardiac and renal histopathology in both sexes and albuminuria in male rats fed high fructose and high salt diet. Functional improvements in cardiorenal parameters may require longer treatment.

Clinical determinants and biomarkers associated with cardiac fibrosis after heart transplantation as assessed by magnetic resonance: Size matters.

Background: Cardiac fibrosis is increasingly recognized as a marker of worse outcomes in long-term follow-up after heart transplantation (HTX). We investigated the clinical determinants and biomarkers of focal and interstitial cardiac fibrosis as assessed with cardiac magnetic resonance (CMR). Methods: Consecutive HTX recipients underwent CMR with late gadolinium enhancement for focal myocardial fibrosis and T1 mapping for interstitial fibrosis. We calculated the correlations of these findings with clinical parameters, history, biomarkers of fibrosis (B-type natriuretic peptide (BNP), growth differentiation factor-15, galectin-3 and soluble ligand ST2) and echocardiography. Results: Forty-eight HTX patients were included: median age 63 ± 13 years, 11 ± 6 years after heart transplantation. Only donor weight (p 0.044) and the rate of a > 30 % mismatch between donor and recipient weight (p 0.02) were significantly different in patients with vs. without late LGE. Extracellular volume (ECV) was correlated with the weight mismatch between donor and recipient (r = 0.32, p 0.04), resulting in a higher ECV for oversized donors. BNP was the only biomarker of the four studied that was correlated with interstitial fibrosis as assessed by ECV (r = 0.35, p 0.04). T1 relaxation time was correlated with treated acute cellular rejection grade ≥ 2 (ISHLT grading) (r = 0.34, p 0.02). Conclusion: Both focal and interstitial fibrosis, as determined by CMR, after heart transplantation are correlated with donor and recipient weight mismatch. BNP was the only biomarker clinically relevant to interstitial cardiac fibrosis.

Application of Compounds with Anti-Cardiac Fibrosis Activity: A Review.

Coronary heart disease, hypertension, myocarditis, and valvular disease cause myocardial fibrosis, leading to heart enlargement, heart failure, heart rate failure, arrhythmia, and premature ventricular beat, even defibrillation can increase the risk of sudden death. Although cardiac fibrosis is common and widespread, there are still no effective drugs to provide adequate clinical intervention for cardiac fibrosis. In this review article, we classify the compounds for treating cardiac fibrosis into natural products, synthetic compounds, and patent drugs according to their sources. Additionally, the structures, activities and signaling pathways of these compounds are discussed. This review provides insight and could provide a reference for the design of new anti-cardiac fibrosis compounds and the new use of older drugs.

Corrigendum: a novel αB-crystallin R123W variant drives hypertrophic cardiomyopathy by promoting maladaptive calcium-dependent signal transduction.

[This corrects the article DOI: 10.3389/fcvm.2023.1223244.].

PiRNA CFAPIR inhibits cardiac fibrosis by regulating the muscleblind-like protein MBNL2.

Myocardial fibroblasts transform into myofibroblasts during the progression of cardiac fibrosis, together with excessive cardiac fibroblast proliferation. Hence, the prevention and treatment of cardiac fibrosis are significant factors for inhibiting the development of heart failure. P-element Induced WImpy testis-interacting RNAs (PiRNA) are widely expressed in the heart, but their involvement in cardiac fibrosis has not yet been confirmed. We identified differentially expressed PiRNAs using Arraystar PiRNA expression profiling in Angiotensin II models of cardiac fibrosis in vivo and in vitro. We then explored cardiac-fibrosis-associated PiRNA-related proteins, RNA-protein interactomes, immunoprecipitation, and pulldown. We detected fibrosis markers and pathway-related proteins using immunofluorescence, qRT-PCR, and Western blot. We uncovered cardiac fibrosis associated PiRNA (CFAPIR) that was obviously dysregulated during cardiac fibrosis, whereas its overexpression reversed fibrosis in vivo and in vitro. Mechanistically, CFAPIR competitively bound muscleblind like protein 2 (MBNL2) and the cyclin-dependent kinase inhibitor P21 to regulate the TGF-ß1/SMAD3 signaling pathway.

miR-450a-2-3p targets ERK(1/2) to ameliorate ISO-induced cardiac fibrosis in mice.

OBJECTIVE: Cardiac fibrosis is an important contributor to atrial fibrillation (AF). Our aim was to identify biomarkers for AF using bioinformatics methods and explore the regulatory mechanism of miR-450a-2-3p in cardiac fibrosis in mice. METHODS: Two datasets, GSE115574 and GSE79768, were obtained from the Gene Expression Omnibus (GEO) database and subsequently merged for further analysis. Differential gene expression analysis was performed to identify differentially expressed genes (DEGs) and miR-450a-2-3p-related differentially expressed genes (MRDEGs). To investigate the underlying mechanism of cardiac fibrosis, a mouse model was established by treating mice with isoproterenol (ISO) and the miR-450a-2-3p agomir. RESULTS: A total of 127 DEGs and 31 MRDEGs were identified and subjected to Gene Ontology (GO) functional enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis to determine the functions and pathways involved in AF. In the animal model, histological analysis using HE and Masson staining, as well as quantification of the collagen volume fraction (CVF), was performed. The increased expression of α-smooth muscle actin (α-SMA), collagen type I (COL1), collagen type III (COL3), and extracellular signal-regulated kinase 1/2 (ERK(1/2)) at both the transcriptional and translational levels indicated the significant development of myocardial fibrosis in mice induced with isoproterenol (ISO). In addition, the cross-sectional area of cardiomyocytes and the expression of atrial natriuretic peptide (NPPA) and brain natriuretic peptide (NPPB) were increased in the ISO group compared with the control group. However, after overexpression of the miR-450a-2-3p agomir through caudal vein injection, there was a notable improvement in cardiac morphology in the treated group. The expression levels of α-SMA, COL1, COL3, ERK(1/2), NPPA, and NPPB were also significantly decreased. CONCLUSION: Our study reveals the mechanistic connection between ISO-induced myocardial fibrosis and the miR-450a-2-3p/ERK(1/2) signaling pathway, highlighting its role in the development of cardiac fibrosis. Modulating miR-450a-2-3p expression and inhibiting ERK(1/2) activation are promising approaches for therapeutic intervention in patients with AF.

Platelet and Erythrocyte Membranes Coassembled Biomimetic Nanoparticles for Heart Failure Treatment.

Cardiac fibrosis is a prevalent pathological process observed in the progression of numerous cardiovascular diseases and is associated with an increased risk of sudden cardiac death. Although the BRD4 inhibitor JQ1 has powerful antifibrosis properties, its clinical application is extremely limited due to its side effects. There remains an unmet need for effective, safe, and low-cost treatments. Here, we present a multifunctional biomimetic nanoparticle drug delivery system (PM&EM nanoparticles) assembled by platelet membranes and erythrocyte membranes for targeted JQ1 delivery in treating cardiac fibrosis. The platelet membrane endows PM&EM nanoparticles with the ability to target cardiac myofibroblasts and collagen, while the participation of the erythrocyte membrane enhances the long-term circulation ability of the formulated nanoparticles. In addition, PM&EM nanoparticles can deliver sufficient JQ1 with controllable release, achieving excellent antifibrosis effects. Based on these advantages, it is demonstrated in both pressures overloaded induced mouse cardiac fibrosis model and MI-induced mouse cardiac fibrosis that injection of the fusion membrane biomimetic nanodrug carrier system effectively reduced fibroblast activation, collagen secretion, and improved cardiac fibrosis. Moreover, it significantly mitigated the toxic and side effects of long-term JQ1 treatment on the liver, kidney, and intestinal tract. Mechanically, bioinformatics prediction and experimental validation revealed that PM&EM/JQ1 NPs reduced liver and kidney damage via alleviated oxidative stress and mitigated cardiac fibrosis via the activation of oxidative phosphorylation activation. These results highlight the potential value of integrating native platelet and erythrocyte membranes as a multifunctional biomimetic drug delivery system for treating cardiac fibrosis and preventing drug side effects.

Baricitinib alleviates cardiac fibrosis and inflammation induced by chronic sympathetic activation.

Cardiac fibrosis is characterized by the over-proliferation, over-transdifferentiation and over-deposition of extracellular matrix (ECM) of cardiac fibroblasts (CFs). Cardiac sympathetic activation is one of the leading causes of myocardial fibrosis. Meanwhile, cardiac fibrosis is often together with cardiac inflammation, which accelerates fibrosis by mediating inflammatory cytokines secretion. Recently, the Janus kinase/signal transducer and activator of transcription (JAK/STAT3) signaling pathway has been confirmed by its vital role during the progression of cardiac fibrosis. Thus, JAK/STAT3 signaling pathway is thought to be a potential therapeutic target for cardiac fibrosis. Baricitinib (BR), a novel JAK1/2 inhibitor, has been reported excellent effects of anti-fibrosis in multiple fibrotic diseases. However, little is known about whether and how BR ameliorates cardiac fibrosis caused by chronic sympathetic activation. Isoproterenol (ISO), a ß-Adrenergic receptor (ß-AR) nonselective agonist, was used to modulate chronic sympathetic activation in mice. As expected, our results proved that BR ameliorated ISO-induced cardiac dysfunction. Meanwhile, BR attenuated ISO-induced cardiac fibrosis and cardiac inflammation in mice. Moreover, BR also inhibited ISO-induced cardiac fibroblasts activation and macrophages pro-inflammatory secretion. As for mechanism studies, BR reduced ISO-induced cardiac fibroblasts by JAK2/STAT3 and PI3K/Akt signaling, while reduced ISO-induced macrophages pro-inflammatory secretion by JAK1/STAT3 and NF-κB signaling. In summary, BR alleviates cardiac fibrosis and inflammation caused by chronic sympathetic activation. The underlying mechanism involves BR-mediated suppression of JAK1/2/STAT3, PI3K/Akt and NF-κB signaling.

Inhibition of MMP2 activity mitigates N-omega-nitro-l-arginine-methyl ester (l-NAME)-induced right heart failure.

In rats decreased bioavailability of nitric oxide induces oxidative stress and right heart failure. Oxidative stress can activate matrix metalloproteinase-2 (MMP2). We addressed the question whether increasing oxidative defense by administration of the SOD mimetic Tempol or direct inhibition of MMP2 activity by SB-3CT mitigates right heart failure. Rats received l-NAME for four weeks and during week three and four treatment groups received either Tempol or SB-3CT in addition. After four weeks heart function was analyzed by echocardiography, organ weights and expression of NPPB and COL1A1 were analyzed, oxidative stress was monitored by DHE-staining and MMP2 activity was quantified by proteolytic auto-activation, zymography, and troponin I degradation. l-NAME induced oxidative stress and MMP2 activity stronger in the right ventricle than in the left ventricle. Troponin I, a MMP2 substrate, was degraded in right ventricles. Tempol reduced oxidative stress and preferentially affected the expression of fibrotic genes (i.e. COL1A1) and fibrosis. Tempol and SB-3CT mitigated right but not left ventricular hypertrophy. Neither SB-3CT nor Tempol alone strongly improved right ventricular function. In conclusion, both MMP2 activity and oxidative stress contribute to right ventricular failure but neither is MMP2 activation linked to oxidative stress nor does oxidative stress and MMP2 activity have common targets.