Cardiac myosin binding protein C (MYBPC3) is the most commonly mutated gene associated with hypertrophic cardiomyopathy (HCM). Haploinsufficiency of full-length MYBPC3 and disruption of proteostasis have both been proposed as central to HCM disease pathogenesis. Discriminating the relative contributions of these 2 mechanisms requires fundamental knowledge of how turnover of WT and mutant MYBPC3 proteins is regulated. We expressed several disease-causing mutations in MYBPC3 in primary neonatal rat ventricular cardiomyocytes. In contrast to WT MYBPC3, mutant proteins showed reduced expression and failed to localize to the sarcomere. In an unbiased coimmunoprecipitation/mass spectrometry screen, we identified HSP70-family chaperones as interactors of both WT and mutant MYBPC3. Heat shock cognate 70 kDa (HSC70) was the most abundant chaperone interactor. Knockdown of HSC70 significantly slowed degradation of both WT and mutant MYBPC3, while pharmacologic activation of HSC70 and HSP70 accelerated degradation. HSC70 was expressed in discrete striations in the sarcomere. Expression of mutant MYBPC3 did not affect HSC70 localization, nor did it induce a protein folding stress response or ubiquitin proteasome dysfunction. Together these data suggest that WT and mutant MYBPC3 proteins are clients for HSC70, and that the HSC70 chaperone system plays a major role in regulating MYBPC3 protein turnover.
Amelia A. Glazier, Neha Hafeez, Dattatreya Mellacheruvu, Venkatesha Basrur, Alexey I. Nesvizhskii, Lap Man Lee, Hao Shao, Vi Tang, Jaime M. Yob, Jason E. Gestwicki, Adam S. Helms, Sharlene M. Day
Despite the long-standing recognition that the immune response to acute myocardial injury contributes to adverse left ventricular (LV) remodeling, it has not been possible to effectively target this clinically. Using 2 different in vivo models of acute myocardial injury, we show that pirfenidone confers beneficial effects in the murine heart through an unexpected mechanism that depends on cardiac B lymphocytes. Naive hearts contained a large population of CD19+CD11b–CD23–CD21–IgD+IgMlo lymphocytes, and 2 smaller populations of CD19+CD11b+ B1a and B1b cells. In response to tissue injury, there was an increase in neutrophils, monocytes, macrophages, as well as an increase in CD19+ CD11b– B lymphocytes. Treatment with pirfenidone had no effect on the number of neutrophils, monocytes, or macrophages, but decreased CD19+CD11b– lymphocytes. B cell depletion abrogated the beneficial effects of pirfenidone. In vitro studies demonstrated that stimulation with lipopolysaccharide and extracts from necrotic cells activated CD19+ lymphocytes through a TIRAP-dependent pathway. Treatment with pirfenidone attenuated this activation of B cells. These findings reveal a previously unappreciated complexity of myocardial B lymphocytes within the inflammatory infiltrate triggered by cardiac injury and suggest that pirfenidone exerts beneficial effects in the heart through a unique mechanism that involves modulation of cardiac B lymphocytes.
Luigi Adamo, Lora J. Staloch, Cibele Rocha-Resende, Scot J. Matkovich, Wenlong Jiang, Geetika Bajpai, Carla J. Weinheimer, Attila Kovacs, Joel D. Schilling, Philip M. Barger, Deepta Bhattacharya, Douglas L. Mann
BACKGROUND. Cardiac positron emission testing (PET) is more accurate than single photon emission computed tomography (SPECT) at identifying coronary artery disease (CAD); however, the 2 modalities have not been thoroughly compared in a real-world setting. We conducted a retrospective analysis of 60-day catheterization outcomes and 1-year major adverse cardiovascular events (MACE) after the transition from a SPECT- to a PET-based myocardial perfusion imaging (MPI) program. METHODS. MPI patients at Intermountain Medical Center from January 2011–December 2012 (the SPECT era, n = 6,777) and January 2014–December 2015 (the PET era, n = 7,817) were studied. Outcomes studied were 60-day coronary angiography, high-grade obstructive CAD, left main/severe 3-vessel disease, revascularization, and 1-year MACE-revascularization (MACE-revasc; death, myocardial infarction [MI], or revascularization >60 days). RESULTS. Patients were 64 ± 13 years old; 54% were male and 90% were of European descent; and 57% represented a screening population (no prior MI, revascularization, or CAD). During the PET era, compared with the SPECT era, a higher percentage of patients underwent coronary angiography (13.2% vs. 9.7%, P < 0.0001), had high-grade obstructive CAD (10.5% vs. 6.9%, P < 0.0001), had left main or severe 3-vessel disease (3.0% vs. 2.3%, P = 0.012), and had coronary revascularization (56.7% vs. 47.1%, P = 0.0001). Similar catheterization outcomes were seen when restricted to the screening population. There was no difference in 1-year MACE-revasc (PET [5.8%] vs. SPECT [5.3%], P = 0.31). CONCLUSIONS. The PET-based MPI program resulted in improved identification of patients with high-grade obstructive CAD, as well as a larger percentage of revascularization, thus resulting in fewer patients undergoing coronary angiography without revascularization. FUNDING. This observational study was funded using internal departmental funds.
Stacey Knight, David B. Min, Viet T. Le, Kent G. Meredith, Ritesh Dhar, Santanu Biswas, Kurt R. Jensen, Steven M. Mason, Jon-David Ethington, Donald L. Lappe, Joseph B. Muhlestein, Jeffrey L. Anderson, Kirk U. Knowlton
Elevated levels of brain natriuretic peptide (BNP) are regarded as an early compensatory response to cardiac myocyte hypertrophy, although exogenously administered BNP shows poor clinical efficacy in heart failure and hypertension. We tested whether phosphodiesterase 2A (PDE2A), which regulates the action of BNP-activated cyclic guanosine monophosphate (cGMP), was directly involved in modulating Ca2+ handling from stellate ganglia (SG) neurons and cardiac norepinephrine (NE) release in rats and humans with an enhanced sympathetic phenotype. SG were also isolated from patients with sympathetic hyperactivity and healthy donor patients. PDE2A activity of the SG was greater in both spontaneously hypertensive rats (SHRs) and patients compared with their respective controls, whereas PDE2A mRNA was only high in SHR SG. BNP significantly reduced the magnitude of the calcium transients and ICaN in normal Wistar Kyoto (WKY) SG neurons, but not in the SHRs. cGMP levels stimulated by BNP were also attenuated in SHR SG neurons. Overexpression of PDE2A in WKY neurons recapitulated the calcium phenotype seen in SHR neurons. Functionally, BNP significantly reduced [3H]-NE release in the WKY rats, but not in the SHRs. Blockade of overexpressed PDE2A with Bay 60-7550 or overexpression of catalytically inactive PDE2A reestablished the modulatory action of BNP in SHR SG neurons. This suggests that PDE2A may be a key target in modulating the action of BNP to reduce sympathetic hyperactivity.
Kun Liu, Dan Li, Guoliang Hao, David McCaffary, Oliver Neely, Lavinia Woodward, Demetris Ioannides, Chieh-Ju Lu, Marcella Brescia, Manuela Zaccolo, Harikrishna Tandri, Olujimi A. Ajijola, Jeffrey L. Ardell, Kalyanam Shivkumar, David J. Paterson
BACKGROUND. Systemic lupus erythematosus (SLE) is associated with enhanced risk of atherosclerotic cardiovascular disease not explained by Framingham risk score (FRS). Immune dysregulation associated to a distinct subset of lupus proinflammatory neutrophils (low density granulocytes; LDGs) may play key roles in conferring enhanced CV risk. This study assessed if lupus LDGs are associated with in vivo vascular dysfunction and inflammation and coronary plaque. METHODS. SLE subjects and healthy controls underwent multimodal phenotyping of vascular disease by quantifying vascular inflammation (18F-fluorodeoxyglucose–PET/CT [18F-FDG–PET/CT]), arterial dysfunction (EndoPAT and cardio-ankle vascular index), and coronary plaque burden (coronary CT angiography). LDGs were quantified by flow cytometry. Cholesterol efflux capacity was measured in high-density lipoprotein–exposed (HDL-exposed) radioactively labeled cell lines. Whole blood RNA sequencing was performed to assess associations between transcriptomic profiles and vascular phenotype. RESULTS. Vascular inflammation, arterial stiffness, and noncalcified plaque burden (NCB) were increased in SLE compared with controls even after adjustment for traditional risk factors. In SLE, NCB directly associated with LDGs and associated negatively with cholesterol efflux capacity in fully adjusted models. A neutrophil gene signature reflective of the most upregulated genes in lupus LDGs associated with vascular inflammation and NCB. CONCLUSION. Individuals with SLE demonstrate vascular inflammation, arterial dysfunction, and NCB, which may explain the higher reported risk for acute coronary syndromes. The association of LDGs and neutrophil genes with vascular disease supports the hypothesis that distinct neutrophil subsets contribute to vascular damage and unstable coronary plaque in SLE. Results also support previous observations that neutrophils may disrupt HDL function and thereby promote atherogenesis. TRIAL REGISTRATION. Clinicaltrials.gov NCT00001372 FUNDING. Intramural Research Program NIAMS/NIH (ZIA AR041199) and Lupus Research Institute
Philip M. Carlucci, Monica M. Purmalek, Amit K. Dey, Yenealem Temesgen-Oyelakin, Simantini Sakhardande, Aditya A. Joshi, Joseph B. Lerman, Alice Fike, Michael Davis, Jonathan H. Chung, Martin P. Playford, Mohammad Naqi, Pragnesh Mistry, Gustavo Gutierrez-Cruz, Stefania Dell’Orso, Faiza Naz, Taufiq Salahuddin, Balaji Natarajan, Zerai Manna, Wanxia L. Tsai, Sarthak Gupta, Peter Grayson, Heather Teague, Marcus Y. Chen, Hong-Wei Sun, Sarfaraz Hasni, Nehal N. Mehta, Mariana J. Kaplan
Hypertrophic cardiomyopathy (HCM) stems from mutations in sarcomeric proteins that elicit distinct biophysical sequelae, which in turn may yield radically different intracellular signaling and molecular pathologic profiles. These signaling events remain largely unaddressed by clinical trials that have selected patients based on clinical HCM diagnosis, irrespective of genotype. In this study, we determined how two mouse models of HCM differ, with respect to cellular/mitochondrial function and molecular biosignatures, at an early stage of disease. We show that hearts from young R92W-TnT and R403Q-αMyHC mutation–bearing mice differ in their transcriptome, miRNome, intracellular redox environment, mitochondrial antioxidant defense mechanisms, and susceptibility to mitochondrial permeability transition pore opening. Pathway analysis of mRNA-sequencing data and microRNA profiles indicate that R92W-TnT mutants exhibit a biosignature consistent with activation of profibrotic TGF-β signaling. Our results suggest that the oxidative environment and mitochondrial impairment in young R92W-TnT mice promote activation of TGF-β signaling that foreshadows a pernicious phenotype in young individuals. Of the two mutations, R92W-TnT is more likely to benefit from anti–TGF-β signaling effects conferred by angiotensin receptor blockers and may be responsive to mitochondrial antioxidant strategies in the early stage of disease. Molecular and functional profiling may therefore serve as aids to guide precision therapy for HCM.
Styliani Vakrou, Ryuya Fukunaga, D. Brian Foster, Lars Sorensen, Yamin Liu, Yufan Guan, Kirubel Woldemichael, Roberto Pineda-Reyes, Ting Liu, Jill C. Tardiff, Leslie A. Leinwand, Carlo G. Tocchetti, Theodore P. Abraham, Brian O’Rourke, Miguel A. Aon, M. Roselle Abraham
Using an untargeted metabolomics approach in initial (N = 99 subjects) and replication cohorts (N = 1,162), we discovered and structurally identified a plasma metabolite associated with cardiovascular disease (CVD) risks, N6,N6,N6-trimethyl-L-lysine (trimethyllysine, TML). Stable-isotope-dilution tandem mass spectrometry analyses of an independent validation cohort (N = 2,140) confirmed TML levels are independently associated with incident (3-year) major adverse cardiovascular event risks (hazards ratio [HR], 2.4; 95% CI, 1.7–3.4) and incident (5-year) mortality risk (HR, 2.9; 95% CI, 2.0–4.2). Genome-wide association studies identified several suggestive loci for TML levels, but none reached genome-wide significance; and d9(trimethyl)-TML isotope tracer studies confirmed TML can serve as a nutrient precursor for gut microbiota–dependent generation of trimethylamine (TMA) and the atherogenic metabolite trimethylamine N-oxide (TMAO). Although TML was shown to be abundant in both plant- and animal-derived foods, mouse and human fecal cultures (omnivores and vegans) showed slow conversion of TML to TMA. Furthermore, unlike chronic dietary choline, TML supplementation in mice failed to elevate plasma TMAO or heighten thrombosis potential in vivo. Thus, TML is identified as a strong predictor of incident CVD risks in subjects and to serve as a dietary precursor for gut microbiota–dependent generation of TMAO; however, TML does not appear to be a major microbial source for TMAO generation in vivo.
Xinmin S. Li, Zeneng Wang, Tomas Cajka, Jennifer A. Buffa, Ina Nemet, Alex G. Hurd, Xiaodong Gu, Sarah M. Skye, Adam B. Roberts, Yuping Wu, Lin Li, Christopher J. Shahen, Matthew A. Wagner, Jaana A. Hartiala, Robert L. Kerby, Kymberleigh A. Romano, Yi Han, Slayman Obeid, Thomas F. Lüscher, Hooman Allayee, Federico E. Rey, Joseph A. DiDonato, Oliver Fiehn, W.H. Wilson Tang, Stanley L. Hazen
Loss-of-function mutations in genes encoding contractile proteins have been observed in thoracic aortic aneurysms (TAA). To gain insight into the contribution of contractile protein deficiency in the pathogenesis of TAA, we examined human aneurysm samples. We found multiple contractile gene products deficient in TAA samples, and in particular, expression of SM22α was inversely correlated with aneurysm size. SM22α-deficient mice demonstrated pregnancy-induced aortic dissection, and SM22α deficiency worsened aortic aneurysm in Fbn1C1039G/+ (Marfan) mice, validating this gene product as a TAA effector. We found that repression of SM22α was enforced by increased activity of the methyltransferase EZH2. TGF-β effectors such as SMAD3 were excluded from binding SM22α-encoding chromatin (TAGLN) in TAA samples, while treatment with the EZH2 inhibitor GSK343 improved cytoskeletal architecture and restored SM22α expression. Finally, inhibition of EZH2 improved aortic performance in Fbn1C1039G/+ mice, in association with restoration of contractile protein expression (including SM22α). Together, these data inform our understanding of contractile protein deficiency in TAA and support the pursuit of chromatin modifying factors as therapeutic targets in aortic disease.
Christian L. Lino Cardenas, Chase W. Kessinger, Carolyn MacDonald, Arminder S. Jassar, Eric M. Isselbacher, Farouc A. Jaffer, Mark E. Lindsay
Myocardial infarctions (MIs) cause the loss of myocytes due to lack of sufficient oxygenation and latent revascularization. Although the administration of histone deacetylase (HDAC) inhibitors reduces the size of infarctions and improves cardiac physiology in small-animal models of MI injury, the cellular targets of the HDACs, which the drugs inhibit, are largely unspecified. Here, we show that WNT-inducible secreted protein-1 (Wisp-1), a matricellular protein that promotes angiogenesis in cancers as well as cell survival in isolated cardiac myocytes and neurons, is a target of HDACs. Further, Wisp-1 transcription is regulated by HDACs and can be modified by the HDAC inhibitor, suberanilohydroxamic acid (SAHA/vorinostat), after MI injury. We observe that, at 7 days after MI, Wisp-1 is elevated 3-fold greater in the border zone of infarction in mice that experience an MI injury and are injected daily with SAHA, relative to MI alone. Additionally, human coronary artery endothelial cells (HCAECs) produce WISP-1 and are responsive to autocrine WISP-1–mediated signaling, which functionally promotes their proangiogenic behavior. Altering endogenous expression of WISP-1 in HCAECs directly impacts their network density in vitro. Therapeutic interventions after a heart attack define the extent of infarct injury, cell survival, and overall prognosis. Our studies shown here identify a potentially novel cardiac angiokine, Wisp-1, that may contribute to beneficial post-MI treatment modalities.
Lillianne H. Wright, Daniel J. Herr, Symone S. Brown, Harinath Kasiganesan, Donald R. Menick
Heart failure with preserved ejection fraction (HFpEF) can arise from cardiac and vascular remodeling processes following long-lasting hypertension. Efficacy of common HF therapeutics is unsatisfactory in HFpEF. Evidence suggests that stimulators of the nitric oxide–sensitive soluble guanylyl cyclase (NOsGC) could be of use here. We aimed to characterize the complex cardiovascular effects of NOsGC stimulation using NO-independent stimulator BAY 41-8543 in a double-transgenic rat (dTGR) model of HFpEF. We show a drastically improved survival rate of treated dTGR. We observed less cardiac fibrosis, macrophage infiltration, and gap junction remodeling in treated dTGR. Microarray analysis revealed that treatment of dTGR corrected the dysregulateion of cardiac genes associated with fibrosis, inflammation, apoptosis, oxidative stress, and ion channel function toward an expression profile similar to healthy controls. Treatment reduced systemic blood pressure levels and improved endothelium-dependent vasorelaxation of resistance vessels. Further comprehensive in vivo phenotyping showed an improved diastolic cardiac function, improved hemodynamics, and less susceptibility to ventricular arrhythmias. Short-term BAY 41-8543 application in isolated untreated transgenic hearts with structural remodeling significantly reduced the occurrence of ventricular arrhythmias, suggesting a direct nongenomic role of NOsGC stimulation on excitation. Thus, NOsGC stimulation was highly effective in improving several HFpEF facets in this animal model, underscoring its potential value for patients.
Nicola Wilck, Lajos Markó, András Balogh, Kristin Kräker, Florian Herse, Hendrik Bartolomaeus, István A. Szijártó, Maik Gollasch, Nadine Reichhart, Olaf Strauss, Arnd Heuser, Damian Brockschnieder, Axel Kretschmer, Ralf Lesche, Florian Sohler, Johannes-Peter Stasch, Peter Sandner, Friedrich C. Luft, Dominik N. Müller, Ralf Dechend, Nadine Haase
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