Author + information
- Received November 24, 2018
- Revision received February 25, 2019
- Accepted February 26, 2019
- Published online May 27, 2019.
- Keyvan Yousefi, PharmDa,b,∗,
- Camila I. Irion, PhDb,c,∗,
- Lauro M. Takeuchi, DDSb,
- Wen Ding, PhDa,b,
- Guerline Lambert, MSb,c,
- Trevor Eisenberg, BSc,
- Sarah Sukkar, BSc,
- Henk L. Granzier, PhDd,
- Mei Methawasin, MD, PhD, BSd,
- Dong I. Lee, PhDe,
- Virginia S. Hahn, MDe,
- David A. Kass, MDe,
- Konstantinos E. Hatzistergos, PhDb,f,
- Joshua M. Hare, MDb,c,
- Keith A. Webster, PhDa,g and
- Lina A. Shehadeh, PhDb,c,g,∗ (, )@umiamimedicine
- aDepartment of Molecular and Cellular Pharmacology, University of Miami Leonard M. Miller School of Medicine, Miami, Florida
- bInterdisciplinary Stem Cell Institute, University of Miami Leonard M. Miller School of Medicine, Miami, Florida
- cDepartment of Medicine, Division of Cardiology, University of Miami Leonard M. Miller School of Medicine, Miami, Florida
- dDepartment of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona
- eDivision of Cardiology, Department of Medicine, Johns Hopkins University, Baltimore, Maryland
- fDepartment of Cell Biology, University of Miami Leonard M. Miller School of Medicine, Miami, Florida
- gVascular Biology Institute and Peggy and Harold Katz Family Drug Discovery Center, University of Miami Leonard M. Miller School of Medicine, Miami, Florida
- ↵∗Address for correspondence:
Dr. Lina A. Shehadeh, Interdisciplinary Stem Cell Institute, University of Miami Leonard M. Miller School of Medicine, 1501 NW 10th Avenue, Biomedical Research Building Room 818, Miami, Florida 33136.
Background Patients with chronic kidney disease (CKD) and coincident heart failure with preserved ejection fraction (HFpEF) may constitute a distinct HFpEF phenotype. Osteopontin (OPN) is a biomarker of HFpEF and predictive of disease outcome. We recently reported that OPN blockade reversed hypertension, mitochondrial dysfunction, and kidney failure in Col4a3−/− mice, a model of human Alport syndrome.
Objectives The purpose of this study was to identify potential OPN targets in biopsies of HF patients, healthy control subjects, and human induced pluripotent stem cell–derived cardiomyocytes (hiPS-CMs), and to characterize the cardiac phenotype of Col4a3−/− mice, relate this to HFpEF, and investigate possible causative roles for OPN in driving the cardiomyopathy.
Methods OGDHL mRNA and protein were quantified in myocardial samples from patients with HFpEF, heart failure with reduced ejection fraction, and donor control subjects. OGDHL expression was quantified in hiPS-CMs treated with or without anti-OPN antibody. Cardiac parameters were evaluated in Col4a3−/− mice with and without global OPN knockout or AAV9-mediated delivery of 2-oxoglutarate dehydrogenase-like (Ogdhl) to the heart.
Results OGDHL mRNA and protein displayed abnormal abundances in cardiac biopsies of HFpEF (n = 17) compared with donor control subjects (n = 12; p < 0.01) or heart failure with reduced ejection fraction patients (n = 12; p < 0.05). Blockade of OPN in hiPS-CMs conferred increased OGDHL expression. Col4a3−/− mice demonstrated cardiomyopathy with similarities to HFpEF, including diastolic dysfunction, cardiac hypertrophy and fibrosis, pulmonary edema, and impaired mitochondrial function. The cardiomyopathy was ameliorated by Opn−/− coincident with improved renal function and increased expression of Ogdhl. Heart-specific overexpression of Ogdhl in Col4a3−/− mice also improved cardiac function and cardiomyocyte energy state.
Conclusions Col4a3−/− mice present a model of HFpEF secondary to CKD wherein OPN and OGDHL are intermediates, and possibly therapeutic targets.
Heart failure with preserved ejection fraction (HFpEF) is a complex and increasingly prevalent syndrome accounting for more than 50% of all heart failure (HF) cases (1,2). Relative to heart failure with reduced ejection fraction (HFrEF), HFpEF is more prevalent in the elderly and more commonly associated with, and possibly driven by, comorbidities including systemic hypertension, obesity, diabetes mellitus, chronic kidney disease, and coronary artery and microvascular diseases (3–7). Because of the heterogeneous nature of HFpEF and its diverse underlying etiologies, pharmacological strategies including neurohumoral inhibition that are successfully used to treat HFrEF have not shown efficacy in large clinical trials of HFpEF (8–13). Rather, it is proposed that more personalized treatment strategies are required that are tailored to individual HFpEF-specific signaling and phenotypic diversity as reflected by patient presentation and predisposition (1).
Epidemiological analyses suggest that patients with HFpEF in the presence of renal dysfunction represent a distinct phenotype (14,15). Consistent with this, phenomapping studies identified patients with chronic kidney disease (CKD), electrical and myocardial remodeling, pulmonary hypertension, and right ventricular (RV) dysfunction as a subset of HFpEF patients who are at high clinical risk relative to other phenomapped groups (1). Animal models that accurately reproduce the clinical symptoms of different HFpEF subsets would be valuable to identify signaling intermediates and test for safety and efficacy of phenotype-specific interventions.
Recently, we presented evidence that the pro-inflammatory cytokine osteopontin (OPN) plays a causal role in the progression of CKD in Alport (Col4a3−/−) mice, a model of autosomal Alport syndrome (16). Genetic disruption of the OPN gene in Alport mice ameliorated CKD and reversed systemic hypertension and mitochondrial dysfunction (16). Other work, including our own, described causal roles for OPN in cardiovascular disease and heart failure in humans and animal models, where it has been labeled a “remodeling-specific marker” (17–21). Plasma levels of OPN are increased in HFpEF patients and predict outcome (22,23).
Here, we establish that Col4a3−/− mice recapitulate multiple features of HFpEF, phenotypes that are ameliorated by targeting OPN. Alport mice may represent a subset of HFpEF patients wherein CKD is a primary cause of HF.
Animal procedures were approved by the University of Miami Institutional Animal Care and Use Committee. Col4a3−/− mice on 129X1/SvJ background were from Jackson Laboratory (Bar Harbor, Maine) and interbred with C57Bl/6 (Opn−/−) and BALB/c mice at least 10× as described previously (16). 129J mice were used to validate the HFpEF cardiac phenotypes. Disease progression in Col4a3−/− mice is highly dependent on genetic strain (24). Therefore, we used the 129X1/SvJ strain for invasive hemodynamic studies, AAV9-Ogdhl gene therapy, and titin isoform expression. Equal sex numbers were used.
Experimental procedures and statistical analyses are described in detail in the Online Appendix.
Col4a3−/− mice develop diastolic dysfunction with preserved ejection fraction, impaired strain, and pulmonary congestion
We recently reported that Col4a3−/− mice develop systemic hypertension (16). To examine cardiac function in Col4a3−/− mice, echocardiography and 2-dimensional speckle tracking were implemented in 2-month-old mixed genetic background animals and compared with wild-type and Opn−/− littermates (16). Echocardiography revealed left ventricular (LV) diastolic dysfunction of Col4a3−/− hearts. Isovolumetric relaxation time (IVRT) was prolonged from 16.4 ± 1.27 ms in wild-type to 25.69 ± 1.71 ms in Col4a3−/− mice (p < 0.0001), indicating impaired LV relaxation in Col4a3−/− mice (Figure 1A). Additionally, we found significantly increased early transmitral flow velocity to early mitral annulus velocity ratio (E/Eʹ) from 28.47 ± 1.4 to 40.1 ± 2.84 (p < 0.001) in the Col4a3−/− mice (Figure 1B, Online Figure 1). Increased E/Eʹ indicates elevated LV filling pressure and pulmonary artery wedge pressure. The E/A ratio (early to late ventricular filling velocities) was also significantly reduced corroborating impaired LV relaxation in Col4a3−/− mice (p < 0.01) (Figure 1C). The myocardial performance index, also known as the Tei index, was increased in Col4a3−/− mice by 63% compared with the wild-type mice (p < 0.01) (Figure 1D). The Tei index is inversely related to function, consistent with elevated Tei indexes reported in HFpEF patients (25).
Myocardial strain analyses revealed altered myocardial deformation in Col4a3−/− mice via impaired global longitudinal strain (GLS) (−19.70 ± 1.31% in wild-type vs. −15.24 ± 1.88% in Col4a3−/− mice; p < 0.05) and global circumferential strain (GCS) (−23.52 ± 1.03% in wild-type vs. −18.23 ± 1.24% in Col4a3−/− group; p < 0.01) as shown in Figures 1E and 1F, reflecting subclinical systolic dysfunction. This finding is also consistent with the subclinical systolic dysfunction reported in HFpEF patients (26). In addition, maximum opposing wall delay was increased in Col4a3−/− hearts, indicating asynchrony (Online Table 1). Col4a3−/− mice did not show significantly decreased ejection fraction (EF), cardiac output, or stroke volume (Figure 1G, Online Table 1). Col4a3−/− mice showed a significant increase in normalized lung weight, as well as lung wet-to-dry weight ratio consistent with pulmonary congestion, and suggesting congestive heart failure (Figures 1H and 1I) (p < 0.01). Complete echocardiographic and morphometric measurements are presented in Online Tables 1 and 2.
Col4a3−/− mice develop cardiac hypertrophy and fibrosis
Cardiac hypertrophy is common in HFpEF patients; therefore, we quantified cardiac dimensions in Col4a3−/− mice. Echocardiographic measurements revealed significantly increased relative wall thickness, LV anterior wall thickness, and interventricular septum thickness, (p < 0.05) (Online Table 1) indicating gross hypertrophy. Additionally, wheat germ agglutinin staining confirmed increased myocyte cross-sectional area in Col4a3−/− mice compared with control subjects (p < 0.001) (Figures 2A and 2B). We next evaluated fibrosis, a major contributor to HFpEF. Picrosirius Red staining demonstrated a 4.2-fold increase in collagen content of Col4a3−/− hearts compared with wild-type control mice (p < 0.001) (Figures 2C and 2D). In addition, incorporation of EdU, by myosin light chain 2–negative interstitial cells was significantly up-regulated (Figures 2E and 2F), suggesting fibroblast proliferation. Likewise, the number of activated fibroblasts, as indicated by increased area of rough endoplasmic reticulum and collagen deposition, was increased (electron microscopy) (Figure 2G). These data establish the presence of cardiac hypertrophy and fibrosis in Col4a3−/− mice.
OPN deficiency in Col4a3−/− mice ameliorates cardiac dysfunction and prevents hypertrophy and fibrosis
OPN is elevated in the circulation of HFpEF patients and predicts outcome (22,23). We recently reported that Col4a3−/− mice have increased renal and plasma levels of OPN (16). OPN is not up-regulated in the hearts of Col4a3−/− mice. To investigate the effects of OPN down-regulation, Col4a3−/− mice with homozygous and heterozygous deletion of OPN were subjected to cardiac functional and histological analyses. We found significant improvement in cardiac function and remodeling in Col4a3−/− mice with OPN deficiency. OPN deletion ameliorated diastolic function by restoring IVRT, E/Eʹ, E/A, and Tei index (Figures 1A to 1D). Moreover, Col4a3−/− mice on heterozygous or homozygous OPN knockout backgrounds showed normal myocardial wall thickness (Online Table 1) and myocyte cross-sectional area (Figures 2A and 2B). OPN deficiency markedly decreased myocardial fibrosis in Col4a3−/− mice as shown by Picrosiurius Red staining (Figures 2C and 2D, Online Figure 2), reduced Edu incorporation in interstitial cells (Figures 2E and 2F), and reduced collagen fibers and interstitial “activated” fibroblasts (Figure 2G).
Dysregulated Ogdhl in Col4a3−/− hearts
Gene microarray analysis were implemented on total RNA isolated from hearts of 2-month wild-type, Col4a3−/−, and Col4a3−/−Opn−/− mice (n = 3 per group). We identified 19 differentially expressed genes, of which 3 were up-regulated and 16 down-regulated (Figure 3A, Online Table 3). Quantitative real-time polymerase chain reaction results confirmed that the expression of Hbb-b1, Alas2, Cnn1, Aqp7, and Ogdhl genes was significantly lower in Col4a3−/− hearts. In addition to mRNA expression, OGDHL protein levels were decreased in total homogenate and mitochondrial fractions of Col4a3−/− hearts (Figures 3C and 3D) but increased in Col4a3−/−Opn−/− double knockouts (Figure 3F). OGDH enzymatic activity was also significantly lower in extracts from Col4a3−/− hearts (Figure 3E). These data suggest that OGDHL regulation by OPN contributes to the cardiac pathology of Col4a3−/− mice.
Increased oxidative stress and loss of mitochondrial integrity in Col4a3−/− hearts
To further explore abnormalities in energy transduction, we investigated mitochondrial morphology and function in Col4a3−/− hearts. Elevated oxidative stress, including depressed redox state and elevated lipid peroxidation, is common in HF. We found that oxidative stress was markedly elevated in Col4a3−/− hearts, including 50% reduction in the reduced to oxidized glutathione (GSH:GSSG) ratio (Online Figure 3A) and 35% increase in the levels of malondialdehyde (Online Figure 3B). We also found significant reductions in the levels of the mitochondrial electron transport chain complexes I, II, and IV (p < 0.05) (Online Figure 3C). Electron microscopy revealed dysmorphic mitochondria that were swollen with disorganized cristae in Col4a3−/− hearts (Online Figure 3D). Such features of oxidative stress and mitochondrial dysfunction are common in HF patients and animal models (27–29).
Negative regulation of Ogdhl and mitochondria by OPN
To further investigate functional interactions between OPN and OGDHL, we developed a monoclonal antibody against human OPN (OPN mAb). OGDHL protein was quantified in hiPS-CMs after treatment for 24 h with OPN mAb. Immunostaining and western blots showed that neutralization of OPN conferred significant increases in OGDHL (Figures 4A to 4C). In addition, we found that treating mouse neonatal cardiomyocytes with recombinant OPN protein for 48 h significantly suppressed ATP-linked oxygen consumption (Figures 4D and 4E). These data are consistent with negative regulation of OGDHL and mitochondrial respiration by OPN.
Validation of diastolic dysfunction in Col4a3−/− on 129J background
To validate the HFpEF cardiac phenotype of mixed background mice in pure 129J background, the experiments were repeated on Col4a3−/− 129J mice. In contrast to the gross and cellular hypertrophy seen in Col4a3−/− on a mixed background, Col4a3−/− 129J mice did not demonstrate such hypertrophy (Online Table 4). This finding is consistent with previous reports (30,31). However, both echocardiography and invasive hemodynamic measurements confirmed diastolic dysfunction in Col4a3−/− 129J mice similar to the mixed background results. As shown in Figures 5A and 5B, Col4a3−/− 129J mice had significantly prolonged IVRT and markedly increased Tei indexes. However, the Col4a3−/− 129J mice displayed a more compromised systolic function than the mixed background mice. Although EFs were not reduced (Figure 5C), Col4a3−/− 129J mice showed significantly decreased cardiac output and stroke volume (Figures 5D and 5E) (p < 0.05). Moreover, strain analysis in Col4a3−/−129J mice also indicated myocardial deformation shown by impaired GLS and GCS (Figures 5F and 5G), similar to the mixed strain line. Complete echocardiographic and morphometric measurements are presented in Online Tables 4 and 5.
Invasive LV catheterization in Col4a3−/− 129J, as represented in Figure 6A, revealed markedly increased end-diastolic pressure-volume relationship (Figure 6B) (p < 0.01), prolonged time constant of LV relaxation (Tau; p < 0.01) (Figure 6C) and significantly increased dP/dtmin (p < 0.05) (Figure 6D), each supporting diastolic dysfunction. Moreover, LV end-diastolic pressure was increased from 4.6 ± 0.3 in wild-type mice to 8.63 ± 1.01 in the Col4a3−/− 129J group (p < 0.01) (Figure 6E), corroborating elevated LV filling pressures. Complete invasive hemodynamics measurements are presented in Online Table 6.
Although increased up-regulation of titin N2BA isoform was reported in some HFpEF patients as a compensatory response to increased myocardial stiffness (32), it was absent in others (33). We detected no significant changes of titin isoforms in the LV of Col4a3−/− hearts (Online Figure 4).
AAV9-Ogdhl gene therapy in Col4a3−/− mice ameliorates cardiac dysfunction
We performed Ogdhl gene delivery to Col4a3−/− hearts using heart-specific AAV9-cTnT-Ogdhl and AAV9-cTnT-Luciferase as control. Col4a3−/− 129J mice at 4 weeks received single tail vein injections of AAV vectors (1 × 1012 vg/mouse), and gene delivery was confirmed by IVIS imaging, quantitative real-time polymerase chain reaction, and Western blot after an additional 4 weeks (Online Figure 5). Cardiac function was analyzed in parallel by echocardiography. Although Ogdhl overexpression did not change the prolonged IVRT (Figure 5A), the myocardial performance index was significantly reduced relative to uninjected or Luciferase-injected control mice (Figure 5B). Moreover, Ogdhl overexpression markedly improved GLS (Figure 5F) relative to uninjected or Luciferase-injected control mice, suggesting that gene therapy improved cardiac systolic function. Col4a3−/− mice that underwent gene therapy also demonstrated significantly higher body weights relative to uninjected control mice, suggesting a generally improved physiology (Figure 5H). Complete echocardiographic and morphometric measurements are presented in Online Tables 4 and 5.
Compromised mitochondrial respiration is rescued by Ogdhl gene therapy
To directly assess myocardial mitochondrial respiration in Col4a3−/− hearts with and without Ogdhl, Seahorse XF assays were performed on adult cardiac myocytes 4 weeks after AAV9 delivery. We found that over-expression of Ogdhl in Col4a3−/− mice significantly improved mitochondrial function (Figures 5I and 5J). These results support our hypothesis that cardioprotection conferred by OPN deficiency in Col4a3−/− hearts is mediated at least in part through Ogdhl elevation and enhanced energy metabolism.
OGDHL expression is dysregulated in cardiac biopsies of HF patients
To determine whether mitochondrial functions and OGDHL were similarly compromised in the clinical setting, we quantified OGDHL transcript and protein levels in cardiac biopsies from patients with HFpEF, patients with HFrEF, and donor controls. Demographics of the patients are summarized in Table 1. Unexpectedly, we found that transcript levels of Ogdhl were significantly higher in samples from both HFpEF and HFrEF compared with healthy controls whereas OGDHL protein was elevated only in the HFpEF group (Figure 7). Although these results do not support suppression of the Ogdhl gene as a general mechanism underlying global bioenergetic dysfunction during HF, they do suggest that this pathway is dysregulated in both HF groups relative to controls. It should be noted that obesity and diabetes were underlying comorbidities of the HFpEF group relative to controls or HFrEF, and these may influence bioenergetic signaling pathways including OGDHL expression. Therefore, the HFpEF phenotype of this group may be distinct from that driven primarily by CKD in patients or Alport mice.
Cardiac phenotype of Col4a3−/− mice
We show that Alport (Col4a3−/−) mice at age 2 months reproduce multiple phenotypes of HFpEF that were significantly ameliorated by genetic disruption of the OPN gene. Alport mice displayed diastolic dysfunction with preserved EF, myocardial deformation, hypertrophy, fibrosis, pulmonary edema, and mitochondrial dysfunction. We as well as others have previously reported on the renal insufficiency and systemic hypertension in these mice, both of which are also significantly ameliorated by OPN deficiency (16,30). Despite their preserved EFs, Col4a3−/− mice displayed myocardial deformation as indicated by impaired GLS and GCS that is suggestive of the subclinical systolic dysfunction often seen in human HFpEF (26,34).
Role of OPN in driving an HFpEF-like phenotype
Col4a3−/− animals with OPN hetero- or homozygous deletion presented a much more neutral cardiac phenotype with improved diastolic function and decreased myocardial hypertrophy and fibrosis. Microarray analysis identified multiple down-regulated, energetics-related genes in Col4a3−/− hearts that were rescued by OPN deficiency. Of these, OGDHL, a mitochondrial protein involved in metabolic substrate fluxes and signaling (35,36), displayed the most robust response. OGDHL mRNA, protein, and enzyme activity were all substantially decreased in Col4a3−/− hearts, and OGHDL expression was rescued by OPN deficiency. Col4a3−/− mice displayed dysmorphic and dysfunctional cardiac mitochondria with evidence of increased oxidative stress. These defects were also absent in OPN deficient Col4a3−/− mice. Roles for OPN in disruption of mitochondrial functions in the model was further supported by our in vitro studies on isolated cardiac myocytes from mice or hiPS-CMs as well as by Ogdhl gene therapy in vivo. OPN reduced mitochondrial function of cultured cardiac myocytes and cardiac-specific overexpression of Ogdhl in Col4a3−/− hearts reversed the mitochondrial defects. Notably, Ogdhl gene therapy conferred significant improvements in cardiac systolic function, strain, and bioenergetics, consistent with a central role for OPN-induced mitochondrial dysfunction in promoting a HFpEF-like cardiac phenotype in this model.
OGDHL protein levels were increased in cardiac biopsies of HFpEF patients. Depressed OGDHL activity has been associated with neuronal degradation (37) and tumor growth (38), whereas up-regulation of the enzyme has been described in association with stress in the brain and heart (39). Therefore, dysregulation of OGDHL in either direction associated with pathological stress may contribute to CKD-related HFpEF. Further studies are required to fully define the relationships between OPN, OGDHL, and HF and determine whether the OGDHL/OPN axis is a viable therapeutic target in different subsets of HFpEF patients. Although our cellular and gene therapy data showing induced expression of OGDHL by treatment of CMs with an OPN neutralizing antibody and partial reversal of cardiomyopathy by AAV9-Ogdhl (Figure 5) supports direct effects of OPN on OGDHL, we cannot rule out the possibility that global KO of OPN in this model confers a time-restricted cardioprotection by as yet unidentified pathway(s).
Do Col4a3−/− mice model a CKD subtype of HFpEF?
Impaired renal function is a risk factor for developing HFpEF (15,40). Therefore, we considered whether the Alport mouse models a CKD-HFpEF subset. Epidemiology studies indicate that a CKD-HFpEF subset of patients present with more LV hypertrophy, a larger LV systolic functional deficit, impaired left atrial mechanics, and RV dysfunction (15). Our echocardiography and 2-dimensional speckle tracking studies confirmed impaired LV relaxation, elevated LV filling and pulmonary artery wedge pressures, increased myocardial performance index, and normal EF. Strain analyses confirmed myocardial deformation with impaired global longitudinal and circumferential strain reflecting mild systolic dysfunction. Col4a3−/− mice displayed global myocardial hypertrophy, fibrosis, and pulmonary congestion consistent with CHF. These changes are consistent with such a CKD-induced HFpEF phenotype. Shah et al. (1) recently proposed a personalized medical approach to the treatment of HFpEF wherein each specific phenotype is targeted by polypharmacology. Such an approach may benefit from phenotype-specific animal models that could be used to test for safety and efficacy of such drug combinations. For example, Col4a3−/− mice could be used to test for safety and efficacy of combinations of diuretic agents, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, β-blockers, dobutamine, neprilysin inhibitors, and OPN antagonists (monoclonal antibody or aptamer).
Limitations of our study include imperfect matching of the subset of the clinical HFpEF population (backgrounds of diabetes, obesity, and no data on serum OPN) with the preclinical model of CKD-related HFpEF. Similarly, although the human tissues were obtained from a similar region of the RV, the patients do have altered comorbidity with greater obesity in the HFpEF subjects, for example. Heart transplantation is generally restricted to a body mass index <35 kg/m2, whereas many of our HFpEF patients have higher values. Donor hearts will not have this level of obesity or diabetes as seen in HFpEF. Although some HFrEF patients had DM, it was not as common as in HFpEF. Donor hearts lacked these features by definition. In addition, LV biopsies were taken from mice, although the anatomical mismatching may not be a major concern because in separate analyses, we did examine RV versus LV OGDHL protein expression in HFrEF and nonfailing donors where we could obtain tissue from both ventricles from the same heart, and found them similar (Online Figure 6, Online Table 7).
Another limitation of this study involves the short lifespan and severe nephropathy of the preclinical model. Finally, whereas bioenergetic perturbations involving mitochondrial OGDHL are implicated by our HFpEF-Alport model studies, the discrepancy of OGDHL changes in human versus mouse samples leaves open the possibility that OPN confers its effects by as yet unidentified pathways, possibly involving more global effects of the cytokine on heart and kidney function.
As demonstrated by the Central Illustration, Col4a3−/− mice reproduce a CKD-HFpEF-like phenotype that includes renal and diastolic dysfunction, myocardial deformation, hypertension, cardiac hypertrophy, pulmonary congestion, fibrosis, and bioenergetic deficit. The phenotype is globally ameliorated by down-regulation of OPN, and the cardiac phenotype appears to be driven at least in part by OPN-mediated loss of mitochondrial enzymes including OGDHL.
COMPETENCY IN MEDICAL KNOWLEDGE: The Col4a3−/− mouse exhibits several major pathological features of HFpEF associated with CKD. In this model, blockade of OPN reversed hypertension, mitochondrial dysfunction, and kidney failure.
TRANSLATIONAL OUTLOOK: Further investigation is needed to determine if targeting specific regulators of myocardial energetics could favorably affect the clinical manifestations of HFpEF.
The authors thank the Electron Microscope Core Facility and the Imaging Core Facility at the University of Miami Miller School of Medicine. The authors also are thankful for the invaluable contribution of Dr. Kavita Sharma, Director of the HFpEF Clinical Service at the Johns Hopkins University Hospital, who obtained all of the HFpEF endomyocardial biopsies that were analyzed for this study. The authors also thank Dr. Avi Rosenberg, MD, PhD, from the Department of Pathology at Johns Hopkins University Hospital, who helped with the ProteinSimple capillary immunoassay analysis. The ProteinSimple was in part supported by The Bio-Techne Grant Foundation.
↵∗ Drs. Yousefi and Irion contributed equally to this work.
This work was supported by the following grants (to Dr. Shehadeh): National Institute of Health (R56HL132209 and 1R01HL140468) and the Miami Heart Research Institute. The National Heart, Lung, and Blood Institute’s Gene Therapy Resource Program funded the AAV generation at the Penn Vector Core. Dr. Yousefi is a recipient of an American Heart Association (AHA) pre-doctoral fellowship (18PRE33960070). Dr. Ding is a recipient of a Sublett AHA pre-doctoral fellowship (15PRE22450019). Dr. Hahn is funded by the National Institutes of Health (NIH 2T32HL007227-41). Dr. Hatzistergos has ownership interest with Vestion Inc. Dr. Hare has ownership interest in Heart Genomics, Biscayne Pharma, Vestion, and Longeveron; has received research funding from the National Heart, Lung, and Blood Institute; and has received consultant/advisory fees from Longeveron and Vestion. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
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- Abbreviations and Acronyms
- cardiac myocyte
- heart failure with preserved ejection fraction
- heart failure with reduced ejection fraction
- human-induced pluripotent stem cell
- isovolumetric relaxation time
- 2-oxoglutarate dehydrogenase-like
- Received November 24, 2018.
- Revision received February 25, 2019.
- Accepted February 26, 2019.
- 2019 American College of Cardiology Foundation
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