Coarctation Of Aorta Research Articles

Fetal heart quantification technique improves the prenatal prediction of coarctation of the aorta: A retrospective analysis.

Coarctation of the aorta (CoA) ranks among the most prevalent congenital heart defects and poses a life-threatening risk if left undiagnosed. Herein, we utilized fetal heart quantification (HQ) technology to improve the prenatal prediction of CoA. A retrospective analysis was conducted on 64 fetal cases with suspected aortic arch constriction, identified through prenatal ultrasound findings between November 2020 and March 2022 at the Department of Ultrasound, Sir Run Run Shaw Hospital, Zhejiang University. According to the follow-up results, these cases were divided into two groups: 35 cases confirmed as CoA by postpartum surgery or induction, and 29 cases initially suspected of CoA prenatally but subsequently ruled out postnatally. Additionally, 88 cases of normal fetuses were randomly selected as the control group. Both conventional M-mode ultrasound techniques and Fetal HQ software were utilized for fetal analysis across all groups. Parameters related to the heart were measured, including fetal 4-CV length, width, Global Spherical Index (GSI), Mitral Annular Plane Systolic Excursion (MAPSE), areas and ratios of the left and right ventricles, as well as lengths and ratios of the left and right ventricles. Functional measurements of the left and right ventricles included ejection fraction (EF), fractional area change (FAC), global longitudinal strain (GLS), fractional shortening (FS), end-diastolic diameter (ED), and sphericity index (SI). Left ventricular (LV)-GLS, LV-FAC, LV-EF, and LV-EF Z-score could potentially differentiate between true CoA and false CoA or normal groups and serve as potential indicators for the clinical diagnosis of CoA. The receiver operating characteristic (ROC) curves indicated that LV-GLS and LV-EF Z-score have the greatest predictive power for CoA diagnosis. The segments 6-12 of FS in the confirmed CoA group were significantly lower than those in the false CoA and normal groups. Fetal HQ technology, by assessing changes in the size and shape of the heart, can provide relatively reliable parameter support for the prenatal diagnosis of fetal aortic coarctation.

Jin-Xin-Kang alleviates heart failure by mitigating mitochondrial dysfunction through the Calcineurin/Dynamin-Related Protein 1 signaling pathway

Ethnopharmacological relevanceChronic heart failure (CHF) is a severe consequence of cardiovascular disease, marked by cardiac dysfunction. Jin-Xin-Kang (JXK) is a traditional Chinese herbal formula used for the treatment of CHF. This formula consists of seven medicinal herbs, including Ginseng (Ginseng quinquefolium (L.) Alph.Wood), Astragali Radix (Astragalus membranaceus (Fisch.) Bunge), Salvia miltiorrhiza (Salvia miltiorrhiza Bunge), Descurainiae Semen Lepidii Semen (Descurainia sophia (L.) Webb ex Prantl), Leonuri Herba (Leonurus japonicus Houtt.), Cinnamomi Ramulus (Cinnamomum cassia (L.) J.Presl), and Ilex pubescens (Ilex pubescens Hook. & Arn.). Its clinical efficacy has been validated through prospective randomized controlled studies. However, the specific mechanisms of action for this formula have yet to be elucidated. Aim of the studyThis study aimed to investigate the effect of JXK on mitochondrial function and its mechanism in the treatment of CHF. MethodsJXK components were qualitatively analyzed using UPLC-Q-Orbitrap-MS. HF was induced in mice via transverse aortic constriction (TAC). After successful model establishment, lyophilized JXK-L (4.38 g/kg) and JXK-H (13.14 g/kg) were administered for 8 weeks. In vitro, hypertrophic myocardium was induced using angiotensin II (Ang II) for 48 h, followed by JXK-L and JXK-H treatment. Network pharmacology and molecular docking techniques were used to predict the relevant targets of JXK. Cardiac function, serum markers, and histopathological changes were evaluated to assess cardiac function. Immunofluorescence of Tomm20, mitochondrial membrane potential, and ROS were measured to assess mitochondrial dysfunction. Protein expression of calcineurin (CaN) and Drp1 in the myocardium was assessed by Western blot analysis. ResultsWe detected that the active components of JXK include terpenes, glycosides, flavonoids, amino acids, and alkaloids, among others. In mice with CHF, JXK improved cardiac function and reversed ventricular remodeling. Network pharmacology indicated that JXK can inhibit the calcium signaling pathway. The molecular docking results demonstrated that the active components of JXK effectively bind with CaN. Both in vitro and in vivo experiments confirmed that JXK regulated the CaN/Drp1 pathway and alleviated mitochondrial dysfunction. ConclusionJXK can inhibit the CaN/Drp1 pathway to improve mitochondrial function, and consequently treat CHF.

Coarctation Balloon Angioplasty in a Rare Case with Congenitally Corrected Transposition of the Great Arteries and Ebstein’s Anomaly

The coexistence of aortic coarctation, Ebstein’s anomaly, and transposition of the great arteries is an extremely rare occurrence. In this case report, we present a unique instance of complex congenital heart disease in a neonate who exhibited respiratory distress and cyanosis at birth. Echocardiography revealed several significant findings: congenitally corrected transposition of the great arteries, Ebstein’s tricuspid anomaly, moderate-to-severe tricuspid regurgitation, a small muscular ventricular septal defect, and an abnormal left arch with severe coarctation of the aorta. Due to the patient’s unstable hemodynamic status, balloon angioplasty was performed. Subsequent long-term clinical follow-up confirmed the efficacy of this intervention.

Blocking CTLA-4 promotes pressure overload-induced heart failure via activating Th17 cells.

Targeting cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) with specific antibody offers long-term benefits for cancer immunotherapy but can cause severe adverse effects in the heart. This study aimed to investigate the role of anti-CTLA-4 antibody in pressure overload-induced cardiac remodeling and dysfunction. Transverse aortic constriction (TAC) was used to induce cardiac hypertrophy and heart failure in mice. Two weeks after the TAC treatment, mice received anti-CTLA-4 antibody injection twice a week at a dose of 10 mg/kg body weight. The administration of anti-CTLA-4 antibody exacerbated TAC-induced decline in cardiac function, intensifying myocardial hypertrophy and fibrosis. Further investigation revealed that anti-CTLA-4 antibody significantly elevated systemic inflammatory factors levels and facilitated the differentiation of T helper 17 (Th17) cells in the peripheral blood of TAC-treated mice. Importantly, anti-CTLA-4 mediated differentiation of Th17 cells and hypertrophic phenotype in TAC mice were dramatically alleviated by the inhibition of interleukin-17A (IL-17A) by an anti-IL-17A antibody. Furthermore, the C-X-C motif chemokine receptor 4 (CXCR4) antagonist AMD3100, also reversed anti-CTLA-4-mediated cardiotoxicity in TAC mice. Overall, these results suggest that the administration of anti-CTLA-4 antibody exacerbates pressure overload-induced heart failure by activating and promoting the differentiation of Th17 cells. Targeting the CXCR4/Th17/IL-17A axis could be a potential therapeutic strategy for mitigating immune checkpoint inhibitors-induced cardiotoxicity.

Coarctation of aorta presenting as systemic hypertension in a young adult: A case report

A 33-year-old male who was under investigation for young onset hypertension for nine years had weak lower limb pulse and radio femoral delay on examination. Transthoracic echocardiogram revealed a bicuspid aortic valve, and a CT aortogram detected coarctation of the aorta at the junction of the aortic arch and descending thoracic aorta.Coarctation of the aorta is a rare secondary cause of hypertension in young. Symptoms of presentation may vary depending on the site and severity of coarctation. But the commonest presentation is hypertension in the upper extremity of the body. It could be associated with structural heart disease; the commonest is the bicuspid aortic valve. Treatment options for coarctation of the aorta include balloon angioplasty and surgical repair. Lifelong follow-up is needed in both treatment modalities, even after successful correction.

Anaesthesia for Coarctation of Aorta and Aortic Valve Replacement in Pregnancy - A Challenge

Anaesthesia for Coarctation of Aorta and Aortic Valve Replacement in Pregnancy - A Challenge

Pulmonary Artery Banding and Arch Repair vs Norwood for Unbalanced Atrioventricular Canal Defect

BackgroundThe outcomes of single-ventricle palliation in unbalanced atrioventricular canal defect with coarctation of aorta (uAVC+CoA) have not been well studied. Systemic ventricle outflow tract obstruction has a propensity to develop in these patients after aortic arch repair with pulmonary artery banding (arch-PAB), which may adversely affect survival and Fontan candidacy. MethodsA retrospective review was performed of patients who underwent single-ventricle palliation for uAVC+CoA from 2000 to 2022. Patients were divided into 2 groups based on initial palliation: (1) arch-PAB and (2) Norwood procedure. Demographic and clinical characteristics were analyzed and compared along with survival data. ResultsStage 1 palliation for uAVC+CoA was performed in 41 patients. Arch-PAB was performed in 14 infants and Norwood in 27 infants. Arch-PAB patients had more chromosomal abnormalities (28.6 vs 7.4%, P < .009) and less severe systemic ventricle outflow tract obstruction on baseline echocardiogram (0.0 vs 70.4%, P < .001). Survival to stage 3 palliation was lower for the arch-PAB group (28.6% vs 66.6%, P = .02). Arch-PAB remained a significant risk factor for mortality (hazard ratio, 2.93; 95% CI, 1.05-8.53; P = .04) after adjusting for chromosomal abnormalities and atrioventricular valve regurgitation. After arch-PAB, systemic ventricle outflow tract obstruction was diagnosed in 13 of 14 patients. Echocardiography underestimated the degree of outflow tract obstruction in 10 of 13 arch-PAB patients. ConclusionsArch-PAB has worse outcomes than Norwood for uAVC+CoA. Systemic ventricle outflow tract obstruction develops in almost all patients after arch-PAB. Outflow tract obstruction is underestimated by the echocardiogram and requires a high index of suspicion, along with advanced imaging, to ensure timely diagnosis and management.

Clinical presentation and surgical outcomes in patients with Shone's complex: a systematic review.

Shone's complex comprises ofa combination of congenital cardiac anomalies causing obstructions in the left ventricle's inflow and outflow tracts. This systematic review aims to evaluate the clinical features and surgical outcomes of Shone's complex. An electronic literature search of PubMed and Scopus was performed to identify relevant studies related to the presentation, management, and outcomes of Shone's complex. Two reviewers independently performed selection. Data on study characteristics, participant demographics, interventions, outcomes, and follow-up durations were extracted and analyzed. A total of 691 papers were identified, with 18 studies included in the final analysis. The majority of the studies (n = 12) focused on the pediatric age group. The most common clinical presentations were coarctation of the aorta (n = 17) and mitral stenosis (n = 12). Surgical interventions often involved staged approaches, prioritizing outflow before inflow obstructions. Mitral valve repair was preferred over replacement due to better long-term outcomes (n = 8). Biventricular repair was recommended due to improved postoperative outcomes, but often needed reoperations. Reoperations were common, primarily due to recurrent coarctation (n = 10), subaortic stenosis (n = 8), and mitral valve dysfunction (n = 7). Pulmonary hypertension (n = 10) and arrhythmias (n = 11) were significant complications. Most patients were in modified Ross/NYHA functional class 1 on follow-up. Mortality rates ranged from 4 to 28%, with better outcomes associated with early and strategic surgical interventions. Early diagnosis and biventricular repair were associated with better outcomes while transplantation was often an eventuality. Standardized diagnostic criteria, long-term follow-up, and consensus guidelines are needed to improve the management of this congenital heart disease.

Abstract Tu110: CD36-Mediated Transendothelial Fatty Acid Transport Determines Cardiomyocyte Uptake and is Critical to Limiting a Lipotoxic Ceramide Profile and Supporting Cardiac Function during Pathological Stress.

The heart primarily relies on long chain fatty acid oxidation (LCFA) to meet ATP demand. CD36, is a transmembrane glycoprotein transferase for LCFA uptake widely expressed in several cell types including endothelial cells (ECs), cardiomyocytes (CMs), skeletal myocytes, adipocytes, and monocyte/macrophages. Notably, genetic deficiency of CD36 in humans is associated with hypertrophic cardiomyopathy. The role of CD36 in transendothelial LCFA delivery to CMs under physiologic vs pathologic conditions is unknown. We explored consequences of EC-specific CD36 deletion (EC-CD36 KO mice) on the cardiac response to pressure overload. Lack of EC-CD36 increased severity of left ventricular hypertrophy (LVH), and systolic and diastolic dysfunction at 8 weeks of pressure overload via transverse aortic constriction (TAC), with increases in HW:TL ratio, LV mass by echo, reduced EF (p&lt;0.05), and elevated E/E’ in EC-CD36-KO vs. flox/flox littermate controls (f/f) (p&lt;0.5) (Fig 1). Dynamic mode 13 C NMR revealed delayed 13 C LCFA uptake kinetics (time constant, τ) in CMs of isolated, sham and TAC EC-CD36 KO hearts provided 13 C palmitate + 13 C oleate (0.02 mM each) + 10 mM glucose + 1 mM lactate (Fig 2). 13 C LCFA esterification into triglyceride (TG) was also reduced in EC-CD36-KO vs f/f controls, but without evidence for an additional effect of TAC. The contribution of 13 C LCFA to acetyl CoA entry into oxidation via the TCA cycle, was reduced by lack of EC-CD36 in sham and TAC hearts (p&lt;0.0001) (Fig 2). Consistent with diminished LCFA oxidation, phosphocreatine (PCr) to ATP ratio was also compromised in EC-CD36-KO-TAC hearts (p&lt;0.05). Lack of EC-CD36 during TAC increased 13 C LCFA trafficking to lipotoxic C16 ceramide in EC-CD36 KO hearts (Fig 3). CD36 in ECs is critical to LCFA delivery to CMs during pathological stress on the heart. The imbalance in intramyocellular LCFA dynamics due to restricted transendothelial delivery of LCFA to CMs increased lipotoxic ceramide formation. Thus, EC CD36 is critical to the adaptive cardiac response to pathological stress, and the absence of EC CD36-dependent delivery of LCFA to CMs exacerbates reduced energy potential, adverse cardiac remodeling, and dysfunction during afterload stress.

Abstract Tu099: GDF11 accelerates NF-kB-mediated inflammation prior to reduction in cardiac fibrosis in response to experimental pressure overload.

Background: Cardiac fibrosis is a common pathophysiology in a broad variety of heart diseases. GDF11, a member of the TGF-beta superfamily, can reduce cardiac hypertrophy and fibrosis in the pressure overload model of experimental Trans Aortic Constriction (TAC). However, the molecular mechanisms by which GDF11 can reduce cardiac fibrosis are incompletely described. Hypothesis: GDF11 is known to activate both NF-kB as well as SMAD2/3 signaling which are essential in cardiac fibrosis and hypertrophy processes. We hypothesized that exogenous GDF11 can change the dynamics of early inflammatory NF-kB target genes during the response to pressure overload. Methods: We used mice implanted with AngII-osmotic pumps to induce left ventricular fibrosis. The mice were harvested at different time points: 3, 7, 14, and 28 days post-pump implantation (ppi) to follow the evolution of cardiac fibrosis and cardiac hypertrophy, and to identify the role of GDF11 in modulating these processes. Results: GDF11 delivery (1mg/kg every other day) in AngII mice (AngII+GDF11) induced earlier expression of NF-kB target genes (IL-1beta, IL-6, TNF-alpha – p&gt;0.05) compared to AngII+Veh control group at 3d ppi, revealing accelerated activation of NF-kB response pathways in AngII+GDF11 group. This is associated with faster recruitment of the M1 macrophage population observed by an increased expression of CD86 or iNOS at 3d ppi. We also observed decreased markers of fibroblast activation after GDF11 supplementation, with less collagen deposition (F-CHP) and fibrosis (Masson Trichrome) at 28 days. Conclusions: Our data suggest that exogenous GDF11 changes the dynamics of NF-kB inflammatory mechanisms while reducing later fibrosis. This new finding could suggest that the dynamics of the inflammatory response early after pressure overload is a critical factor in cardiac fibrosis.

Abstract Tu096: The Aryl Hydrocarbon Receptor Agonist, L-Kynurenine, Modulates Cardiac Fibroblast Activation and Antigen Presentation

Background: The Aryl Hydrocarbon Receptor (AHR) is a ubiquitously expressed transcription factor that regulates the cellular response to external stimuli through the binding of ligands including tryptophan metabolites such as L-Kynurenine (L-Kyn). Alterations in tryptophan metabolic pathways and downregulation of myocardial AHR are associated with cardiac inflammation and fibrosis in experimental heart failure (HF) induced by transverse aortic constriction (TAC). We hypothesized cardiac fibroblast (CFB) AHR and its agonism by L-Kyn prevent the pro-fibrotic and pro-inflammatory activity of CFBs in experimental HF. Methods and Results: We performed TAC or sham surgery on Ahr -/- mice and WT littermates for 4 weeks and found that Ahr-/- mice showed significantly decreased contractile function measured by echocardiography, and increased collagen deposition in left ventricular histological sections after TAC compared to WT mice. We performed bulk RNA sequencing in sorted CFB (CD31-CD45-MEFSK4+) from Ahr -/- and WT mice. Gene set enrichment analysis showed Ahr -/- CFB had increased expression in pathways for fibroblast activation, chemokine production, and immune cell recruitment. To investigate the role of L-Kyn agonism of CFB AHR in transformation and contractile function, murine CFB were treated with Transforming Growth Factor β (TGFβ) (100ng/ml) or seeded in collagen discs, in the presence or absence of L-Kyn(100ug/ml). L-Kyn attenuated TGFβ mediated induction of αSMA and collagen 1 protein expression by immunofluorescence and western blot, as well as decreased disc contraction 72h after mechanical activation and release. The role of AHR agonism by L-Kyn on the pro-inflammatory function of CFB was determined in WT CFB treated with IFNγ (100U/ml) in the presence or absence of L-Kyn. IFNγ induction of chemokines Cxcl9 and Cxcl10, as well as MHC-II surface expression were attenuated by L-Kyn, so was T cell adhesion to CFB in co-culture assays. In contrast, L-Kyn had no effect on the ability of CFB to take up and process antigens, as determined by DQ-Ovalbumin internalization quantified by flow cytometry. Conclusions: Our results demonstrate that AHR regulates activation and pro-inflammatory signatures in CFB at baseline, and that stimulation of CFB transformation and pro-inflammatory activity is dampened by agonism with L-Kyn. Current studies are aimed at investigating AHR agonism in the context of pressure overload induced HF in CFB reporter mice.

Abstract Tu073: Mst1 induces cardiac dysfunction through the activation of PERK

Introduction: Mammalian sterile 20-like kinase 1 (Mst1), a major component of the Hippo pathway, promotes cell death and differentiation, but inhibits cell growth, thereby contributing to the development of heart failure. We discovered that Mst1 activates protein kinase RNA-like endoplasmic reticulum kinase (PERK), a kinase responsible for the integrated stress response (ISR). Aim: We investigated whether Mst1-induced PERK activation is involved in the development of heart failure. Methods and results: Mst1 induces phosphorylation of the cytoplasmic domain of PERK, thereby activating it. We generated knock-in mice expressing a PERK mutant, which is not phosphorylated by Mst1, (PERK-KI). Although PERK was activated by tunicamycin, an ER stress inducer, it was not activated by transverse aortic constriction (TAC) in PERK-KI mice in vivo . To investigate the effect of Mst1-induced PERK phosphorylation on cardiac function, cardiac-specific Mst1 transgenic mice (Tg-Mst1) mice were crossed with heterozygous (h) PERK-KI mice (Tg-Mst1-hPERK-KI). The level of phosphorylation of eIF2α, a PERK substrate, was decreased in Tg-Mst1-hPERK-KI mice compared to in Tg-Mst1 mice (0.45-fold, p&lt;0.05). Left ventricular ejection fraction (LVEF) was maintained in Tg-Mst1-hPERK-KI mice compared to in Tg-Mst1 mice (46% vs Tg-Mst1 34%, p&lt;0.05), which was accompanied by reduced fibrosis (3.5% vs Tg-Mst1-hPERK-KI 2.2%, p&lt;0.05) in the heart. We investigated the role of the Mst1-PERK pathway during TAC. Mst1 in wild-type (WT) mice was activated by TAC for 4 weeks (2.4-fold). LVEF was preserved in hPERK-KI mice compared to in WT mice (67% vs WT 46%, p&lt;0.05) after 8 weeks of TAC. Increases in lung weight/tibia length were attenuated in hPERK-KI mice than in WT mice (9.6 vs WT 11.5, p&lt;0.05). Conclusion: Mst1 triggers ISR through phosphorylation of PERK, which in turn plays a significant role in mediating heart failure during pressure overload.

Abstract Tu052: RPN6-Serine14 Phosphorylation by PKA Protects Against Systolic Overload-Induced Cardiac Remodeling and Heart Failure

The ubiquitin-proteasome system is the main proteolytic pathway for quality control (PQC) and regulatory degradation of proteins in living cells. Systolic overload, as seen in hypertension and aortic stenosis, is a leading cause of heart failure (HF). Proteasome functional insufficiency is implicated in HF caused by systolic overload. Previous studies have established that Ser14-RPN6 phosphorylation (pS14-RPN6) mediates the activation of 26S proteasomes by protein kinase A. However, the pathophysiological significance of pS14-RPN6 in systolic overload remains to be established. We hypothesize that pS14-RPN6 helps maintain proteostasis and protects the heart during systolic overload. We observed a significant increase in myocardial pS14-RPN6 and ubiquitin conjugates in human HF of ischemic or non-ischemic etiologies (p=0.020, p=0.034) and similarly in wild type (WT) mice after 2 weeks of transverse aortic constriction (TAC) (p&lt;0.0001, p=0.001). To investigate the role of pS14-RPN6 in vivo, our lab created Rpn6 S14A (S14A) knock-in mice where Ser14-Rpn6 phosphorylation is blocked. Here we have compared the responses to TAC between WT and S14A mice. We found that TAC-induced increases in myocardial proteasome peptidase activities were significantly attenuated, and accumulation of ubiquitin conjugates exacerbated in S14A mice (p&lt;0.0001; p&lt;0.0005). Serial echocardiography revealed that S14A mice displayed significantly greater left ventricular (LV) end-diastolic posterior wall thickness and LV mass to body weight ratios at 1- and 12-week post-TAC (p=0.024, 0.0003; p=0.005, 0.01), and lower ejection fraction at 12-week post-TAC than WT mice (p=0.035). S14A mice also showed greater heart weight to tibial length (TL) and ventricular weight to TL ratios at 1 and 12-week post-TAC (1-week, p=0.043, 0.039; 12-week, p=0.007, 0.006). Wheat germ agglutinin and picrosirius red staining indicated a greater cardiomyocyte cross-sectional area and cardiac fibrosis in 12-week post-TAC S14A mice vs. WT mice (p&lt;0.0001; p=0.005). These novel findings demonstrate compellingly that myocardial pS14-RPN6 helps maintain proteostasis, curtails cardiac hypertrophy and delays heart failure occurrence during systolic overload

Abstract We143: MED12 Dysregulation Disrupts Transcriptional Programs Leading to Dilated Cardiomyopathy

The Mediator complex serves as a bridge to link transcriptional machinery and transcription factors (TFs) to control transcription, but detailed molecular mechanisms of transcriptional regulation by Mediator are not well-understood. Mediator is comprised of the head, middle, and tail submodules that make up the core Mediator, and the transiently associating kinase submodule. The CDK8 kinase submodule acts to regulate Mediator-RNA Polymerase II interaction. MED12 is an essential Mediator component within the kinase submodule and is required for CDK8 kinase activity. In aging models, dysregulated levels of Med12 mRNA are detected in both atria and ventricles by qRT-PCR. MED12 protein levels are also increased in human heart failure biopsies and in the mouse heart after transverse aortic constriction (TAC)-induced heart failure[KB1] . To test the hypothesis that increased levels of MED12 contribute to development of heart failure we generated cardiac-specific Med12 transgenic mice (cTg) by driving increased MED12 expression in cardiomyocytes using the αMHC promoter. Med12 overexpression leads to a progressive decrease in fractional shortening by serial echocardiography. Decreased cardiac function was accompanied by increased cardiac chamber size and dilation, without cardiac fibrosis. RNA sequencing of cardiomyocytes from cTg and control mice revealed that increased levels of MED12 leads to early changes in gene expression programs. Using ingenuity pathway analysis we identified MED12-regulated gene programs including those involved in calcium cycling. MED12 is a transcriptional regulator but does not directly bind DNA. To determine how MED12 regulates gene expression we screened for TFs that interact with MED12. We performed immunoprecipitation of MED12 and by mass spectrometry and determined that MED12 interacts with the TFs MEF2, CREB, and SRF. In follow-up experiments we demonstrated that MED12 interacts with the transcription factor (TF) MEF2 to regulate calcium handling genes. Current studies are focused on determining how MED12 binding coordinates gene expression through multiple TFs in cardiomyocytes. Collectively, our data demonstrate that increased MED12 expression leads to the development of heart failure, in part by dysregulation of gene expression. Therefore, precise regulation of MED12 levels is important to maintain normal cardiac function. [KB1]What about aging?

Abstract Tu084: Endothelial Cell STING contributes to Systolic Dysfunction by modulating cardiomyocyte hypertrophy and capillary density in pressure overload-induced heart failure

Introduction: Cardiomyocyte (CM) hypertrophy, endothelial cell (EC) dysfunction and cardiac inflammation are hallmarks of adverse cardiac remodeling that contribute to heart failure (HF) progression. The “Stimulator of Interferon Genes” (STING) is highly expressed in ECs, the dominant non-CM cell in the heart and contributes to vascular inflammation, yet its role in adverse cardiac remodeling is unknown. We hypothesized that EC STING contributes to systolic dysfunction by modulating adverse remodeling in HF. Methods: Wildtype (WT), global deficient (STING-/-) and inducible EC STING-/- mice or EC STING+/+ littermate controls (Cad5ERTCre2+/–Stingfl/fl treated with Tamoxifen or oil, respectively) were subjected to transverse aortic constriction (TAC) or Sham surgery for 2-8 weeks. Cardiac function was analyzed by echocardiography. Left ventricular (LV) sections were stained with wheat germ agglutinin and isolectin to analyze CM hypertrophy and capillary density. Cardiac leukocytes were analyzed by flow cytometry and gene expression by qPCR. Bulk RNA Sequencing was performed on sorted CD45- CD31+ mouse heart ECs (MHEC) from EC STING+/+ and EC STING-/- after 4 weeks of TAC or sham surgery. ELISA was performed on MHEC supernatant. Results: STING-/- mice did not show a decline in fractional shortening (FS), capillary density or develop LV hypertrophy and had decreased intramyocardial CD45+ leukocytes in response to TAC, compared to WT mice. EC STING-/- mice also showed preserved FS, capillary density, and ameliorated CM hypertrophy over the course of 2, 4 and 8 weeks of TAC, compared to EC STING+/+ mice, despite having similar numbers of myocardial CD45+ leukocytes. RNASeq revealed decreased IL6 transcription, a pro-hypertrophic cytokine, in TAC STING-/- MHECs compared to WT MHECs. Myocardial IL6 gene expression was also reduced in EC STING-/- TAC hearts compared to EC STING+/+. In vitro, STING-/- MHECs had decreased secretion of IL6 protein compared to WT MHECs. Conclusions: Our data demonstrate that EC STING modulates both the EC and cardiac expression of the pro-hypertrophic cytokine IL6, suggesting a mechanism contributing to cardiomyocyte hypertrophy, capillary rarefaction, and systolic dysfunction in response to cardiac pressure overload.

Abstract Tu116: Neurofibromin 2 regulates metabolic gene expression and cardiac responses to pressure overload stress

Background: Neurofibromin 2 (NF2) is a tumor suppressor that can engage multiple signaling pathways to modulate cell proliferation and survival. We previously demonstrated that NF2 mediates cardiomyocyte apoptosis and cardiac injury caused by acute myocardial infarction. Research Aim: The role of NF2 in heart failure remains uncharacterized. This study sought to determine whether NF2 modulates heart failure due to chronic stress. Approach: We generated cardiomyocyte-specific NF2 knockout (cKO) mice, and used transverse aortic constriction (TAC) to generate chronic pressure overload (PO) stress, which elicits cardiac remodeling and failure. Complementary cell-based experiments were performed in neonatal rat ventricular myocytes (NRVMs). We analyzed cardiac function by echocardiographic and hemodynamic analysis. We used RNAseq, ChIP, Seahorse metabolic profiling, and biochemical analyses to investigate underlying mechanisms. Results: We found that NF2 is transiently upregulated in wild-type mouse myocardium in response to early phase of PO, but is downregulated during heart failure. Following TAC, NF2 cKO hearts unexpectedly showed significantly worsened cardiac function, compared to controls. RNAseq analysis indicated downregulation of several metabolic pathways and impaired ERR activity in NF2 cKO hearts. qPCR confirmed significantly reduced ERRβ and ERRγ transcripts and decreased metabolic gene expression. Experiments employing NRMVs confirmed that NF2 promoted expression of ERRβ and ERRγ, and DNA pulldown assays demonstrated NF2 association with ERRβ and ERRγ proximal promoters. Analysis of NRVM bioenergetics demonstrated that NF2 depletion impaired mitochondrial respiration, which was reversed by concomitant expression of ERRγ. Moreover, AAV9-mediated restoration of ERRγ in NF2 cKO mice normalized cardiac function in response to PO. Because NF2 does not directly bind DNA, ongoing studies are leveraging a proteomics-based approach to identify the mediator linking NF2 to ERR isoform expression. Conclusion: Based on these findings, we conclude that transient upregulation of myocardial NF2 expression during PO stress is compensatory and regulates metabolic gene expression according to energy demand.

Abstract Tu055: Prominent effects of p38 MAPK inhibition on the phosphoproteome of a guinea pig model of heart failure and sudden cardiac death

Introduction: The p38 mitogen-activated protein kinase (p38 MAPK), activated by stress, plays a role in cardiac hypertrophy and heart failure (HF). The precise mechanism of action of p38 MAPK remains unclear, which could explain the mixed outcomes in P38 inhibitor trials. Here, we examine the impact of p38 MAPK inhibition on cardiac function and the proteome/phosphoproteome of the failing heart. Objective: To ascertain p38 MAPK’s impact on the progression of HF by inhibiting it with SB203580 (SB) in a guinea pig model of HF and sudden cardiac death. Methods: We assessed the proteomic changes in a previously described guinea pig HF model of ascending aortic constriction and once-daily isoproterenol administration (ACi). Three groups were included: sham-operated controls (Control), ACi, and ACi plus SB treatment (ACiSB). Cardiac function was evaluated by M-Mode echocardiography and proteome/phosphoproteome analysis was performed by multiplexed TMT-labeling and LC-MS/MS. Results: Inhibition of p38 MAPK with SB attenuated but did not fully block HF progression. At 5 weeks, fractional shortening was significantly improved in the ACiSB group compared to ACi (p=0.0037). Furthermore, it significantly decreased cardiac hypertrophy and lung edema (p-values &lt;0.0001 and 0.0003 respectively). Compared to our previous study on the impact of a mitochondrially-targeted antioxidant (MitoTEMPO), SB protected a smaller subset of protein expression changes in HF; However, its impact on the phosphoproteome was substantial, extending beyond known p38 substrates. SB suppressed HF-induced inflammatory pathway proteins, modestly protected against downregulation of some mitochondrial respiratory chain proteins, and prevented maladaptive phosphorylation of several proteins involved in excitation-contraction coupling, including the ryanodine receptor, phospholamban, and cytoskeletal protein phosphorylation. Conclusion: p38 MAPK inhibition offered significant protection against HF, primarily affecting the phosphoproteome with modest effects on protein expression. The data suggests that narrowly targeted p38 MAPK-driven phosphoproteome modifications contribute to cardiac decompensation, despite broad protein expression changes in HF. Differences between MitoTEMPO and SB effects on the HF proteome highlight the plethora of remodeling pathways triggered by mitochondrial ROS including p38 MAPK activation. Our findings emphasize the importance of preventing p38 MAPK to preserve cardiac function.

Abstract Tu128: p22 phox is a critical factor for the prevention of oxidation and stabilization of SERCA2a in the heart.

Introduction: Elevated oxidative stress linked with heart failure is a major cause for the downregulation of sarcoplasmic/endoplasmic reticulum (SR/ER) Ca2+ ATPase 2a (SERCA2a). NADPH oxidase (NOX) complexes are a key source of reactive oxygen species (ROS) in cardiomyocytes. p22 phox , a transmembrane partner of NOX1-4, plays an essential role in mediating ROS production in multiple NOX complexes. We investigated the role of p22 phox in oxidative stress and SERCA2a levels during pressure overload (PO). Question: Does loss of p22 phox alleviate heart failure through reduction of oxidative stress and stabilization of SERCA2a levels during PO? Methods/approach: Cardiac-specific p22 phox knockout ( p22 phox -cKO) mice were subjected to sham operation or transverse aortic constriction (TAC). The p22 phox interactome was analyzed by co-immunoprecipitation and mass spectrometry. Protein cysteine oxidation was probed by biotinylated-iodoacetamide (BIAM) labelling. Results: The p22 phox -cKO mouse heart showed a 30% reduction in Dityrosine levels compared to WT after 4-week TAC (p&lt;0.05) and 50% lower total tissue H 2 O 2 levels compared to WT after 1-week TAC (p&lt;0.01). Unexpectedly, p22 phox -cKO mice had higher mortality (+20%, p&lt;0.05), lung congestion (2-fold, p&lt;0.05), and fibrosis (&gt;40%, p&lt;0.01) and a lower (40%, p&lt;0.01) left ventricle ejection fraction than WT after TAC. p22 phox directly interacted with SERCA2a. Lack of p22 phox led to oxidation of SERCA2a (50% reduction in BIAM labelling, p&lt;0.01) at cysteine 498 and promoted proteasome-mediated degradation of SERCA2a. The relative SERCA2a ATPase activity was unaltered in both WT and p22 phox -cKO mice. Furthermore, in the absence of p22 phox , SERCA2a interacted strongly with HMG-CoA reductase degradation protein 1 (Hrd1), an endoplasmic reticulum-associated degradation (ERAD)-specific E3 ubiquitin ligase. Knockdown of Hrd1 in the presence of p22 phox knockdown restored SERCA2a to 70% of WT levels (ns and p&lt;0.5 vs p22 phox knockdown). SERCA2a C498S knock-in mice exhibited better cardiac function and stable SERCA2a protein levels after TAC compared to WT mice. Conclusion: The loss of p22 phox exacerbated heart failure through increased SERCA2a cysteine 498 oxidation and degradation through ERAD.

Abstract We072: Effects of electronic cigarettes on mouse cardiac lymphatic vessels after TAC surgery

Introduction: Heart failure is a public health concern worldwide. It is known that tobacco smoking is a risk factor of heart failure. Tobacco smoking also causes inflammation reaction and lymphatic dysfunction in the lung. However, the effects of electronic cigarettes (ECIG), as a new method of smoking, on the heart and cardiac lymphatic vessels (lymphatics) are not clear yet. The lymphatic vessels play an important role in maintaining cardiac function by modulating fluid homeostasis and transporting macromolecules. It has been reported that cardiac lymphatic vessel formation limits pressure overload-induced heart failure in C57Bl/6 but not in Balb/c mice. How cardiac lymphatics might contribute to the pathogenesis induced by ECIG is not known. Research Questions: The roles of cardiac lymphatic vessels in responses to ECIG exposure are not investigated. I hypothesize that the toxic effects of ECIG on the heart are partially caused by damaging the cardiac lymphatic vessels. Aim: To determine the effects of ECIG exposure on cardiac lymphatics after Transverse aortic constriction (TAC). Methods: I perform TAC surgery on mice as a heart hypertrophy and chronic heart failure model. Mice after TAC or Sham surgery are treated with different vaping components from ECIG: ECIG, propylene glycol and glycerin (PGVG) as vehicle, and air. After 4 weeks of treatment, hearts were harvested for histological analyses. The lymphatic vessel coverage percentage and morphology were examined by immunostaining. Results: Prior research suggested that genetic background in mice might affect the responses of cardiac lymphatic vessels to TAC-induced heart failure. I have established the TAC model using CD-1 mice. My results showed that CD-1 mice treated with PGVG after TAC do not show a significant difference in cardiac lymphatic vessel density compared to Sham group (p value=0.5951). ECIG treatment also did not affect the lymphatic density significantly compared to PGVG treated mice after sham operation (p value=0.8937). ECIG treated mice after TAC surgery showed a trend of increased lymphatic coverage and more mice are still being processed and will be presented at the conference. Conclusion: PGVG treated CD-1 mice do not show changes in lymphatic vessel density 4 weeks post TAC. Longer time points and more mouse numbers are needed to compare the effects of PGVG and ECIG after TAC induced hypertrophy and heart failure. This research is supported by California TRDRP grant.

Abstract Tu061: Pericyte-mediated perivascular fibrosis in the pressure-overloaded heart is dependent on TGF-β signaling and is restrained by ITGB1.

Background: Pericytes exhibit remarkable phenotypic plasticity and have been implicated in the pathogenesis of fibrosis. Cardiac pericytes are involved in repair and fibrotic remodeling of the infarcted heart; however, their role in the cardiomyopathy induced by pressure overload is not known. We hypothesized that cardiac pericytes may contribute to remodeling of the pressure-overloaded heart by converting into fibroblasts and we examined the molecular signals mediating pericyte activation. Methods and Results: Transverse aortic constriction (TAC) protocols were performed to study the role of pericytes in the pressure-overloaded heart. Using fibroblast:pericyte dual reporter mice and lineage tracing experiments with the inducible NG2 CreER mice (to track pericytes) combined with PDGFRa EGFP reporter mice (to reliably label fibroblasts), we found no pericyte to fibroblast conversion in the pressure-overloaded heart. scRNA-seq demonstrated that pericyte lineage cells do not express fibroblast identity genes after TAC but acquire a fibrogenic phenotype expressing high levels of matricellular genes, growth factors, adhesion molecules and integrins. Bioinformatic analysis identified transforming growth factor (TGF)-b and integrin beta-1 (ITGB1) as important upstream regulators of the transcriptional profile of pericytes after TAC. Pericyte-specific loss of transforming growth factor beta receptor 2 (TGFBR2) attenuated dysfunction and perivascular fibrosis after TAC. In contrast, pericyte-specific ITGB1 loss had deleterious effects increasing mortality, promoting dysfunction, inducing microvascular rarefaction and stimulating a pro-inflammatory and fibrogenic pericyte phenotype. Conclusions: In the pressure-overloaded heart, pericytes acquire a fibrogenic phenotype without converting to fibroblasts. Pericyte-specific activation of TGF-β pathways mediates perivascular myocardial fibrosis after TAC. In contrast, pericyte-specific ITGB1 signaling exerts protective actions, preserving microvascular structure, attenuating inflammation and inhibiting fibrosis.