Model Of Heart Failure With Preserved Ejection Fraction Research Articles

The NLRP3-inflammasome inhibitor MCC950 improves cardiac function in a HFpEF mouse model

Heart failure with preserved ejection fraction (HFpEF) is posing a significant medical challenge due to its growing prevalence, high hospitalization rates and limited response to current treatment options. Accumulating evidence suggests that a comorbidity-driven systemic pro-inflammatory state, including activation of the NLRP3 inflammasome, contributes to the pathogenesis of HFpEF. This study aimed to investigate the potential cardiac protective effects of the selective NLRP3 inhibitor MCC950, in a mouse model of HFpEF. HFpEF was obtained in 18–22 months old female mice using high-fat diet (HFD) and angiotensin II (AngII) infusion. Mice developed HFpEF and comorbidities such as obesity, type 2 diabetes, and hypertension. MCC950 was added to HFD and groups were treated for four weeks until the study endpoint. MCC950 treatment resulted in lower plasma IL-18 levels (-47.3 %), illustrating target engagement. First, we observed that MCC950 treatment improved left ventricular function, demonstrated by enhanced global longitudinal strain (GLS, 3.9 %, P<0.01) and reverse peak longitudinal strain (RPLSR, +46.8 %, P<0.05). Second, MCC950 reduced cardiac hypertrophy (cardiomyocyte size -19.5 %, P<0.001) and fibrosis (-32.5 %, P<0.05), accompanied by lower expression of pro-fibrotic genes. Finally, MCC950 treatment reduced macrophage infiltration in left ventricular tissue and attenuated macrophage accumulation in visceral adipose tissue, even more as compared to caloric restriction. Overall, this suggests that NLRP3 inhibition could be a promising treatment for HFpEF patients with a pro-inflammatory profile, potentially improving heart function, systemic inflammation, and metabolic parameters.

Establishment of a HFpEF model using female Dahl salt-sensitive rats: a valuable tool for elucidating the pathophysiology of HFpEF in women.

The pathogenesis of heart failure with preserved ejection fraction (HFpEF) remains unclear, and effective treatments are limited. HFpEF is more prevalent in females, indicating potential gender differences in its pathogenesis. However, no female HFpEF model animals have been established. Hypertension is a major contributor to HFpEF, and sympathetic activation is thought to play a role in both conditions. This study aimed to establish a female HFpEF model using hypertensive Dahl salt-sensitive rats and to assess the presence of sympathetic activation. Seven-week-old female Dahl salt-sensitive rats were fed an 8% high-salt diet (HS group, n = 6), while a low-salt diet group (LS group, n = 9) served as controls. The HS group exhibited increased systolic blood pressure and heart rate. Echocardiography revealed an increased left ventricular (LV) wall thickness, a decreased E/A ratio, and an increased E/e' ratio, all indicative of diastolic dysfunction without reduced LV ejection fraction. Additionally, the HS group showed elevated LV end-diastolic pressure, LV weight, and lung weight, along with histological cardiomyocyte hypertrophy and interstitial fibrosis. Gene expression markers for cardiac hypertrophy and fibrosis were also increased. Renal function was significantly impaired, and plasma norepinephrine levels were elevated, consistent with heightened pre-sympathetic neuronal activity in the brain. In conclusion, high salt loading from 7 weeks of age in female Dahl salt-sensitive rats induced hypertensive HFpEF phenotypes with LV hypertrophy and fibrosis, and sympathetic activation by 16 to 19 weeks of age. This model provides a valuable tool for studying HFpEF pathophysiology in women.

ALPK2 prevents cardiac diastolic dysfunction in heart failure with preserved ejection fraction.

Protein phosphorylation, controlled by protein kinases, is central to regulating various pathophysiological processes, including cardiac systolic function. The dysregulation of protein kinase activity plays a significant role in the pathogenesis of cardiac systolic dysfunction. While cardiac contraction mechanisms are well documented, the mechanisms underlying cardiac diastole remain elusive. This gap persists owing to the historical focus on systolic dysfunction in heart failure research. Recently, heart failure with preserved ejection fraction (HFpEF), an age-related disease characterized by cardiac diastolic dysfunction, has emerged as a major public health concern. However, its underlying mechanism remains unclear. In this study, we investigated cardiac protein kinases by analyzing the gene expression of 518 protein kinases in human tissues. We identified alpha-kinase 2 (ALPK2) as a novel cardiac-specific atypical kinase and generated tamoxifen-inducible, cardiomyocyte-specific Alpk2-knockout mice and Alpk2-overexpressing mice. Alpk2 deficiency did not affect cardiac systolic dysfunction in the myocardial infarction model or the pressure-overload-induced heart failure model. Notably, cardiomyocyte-specific Alpk2 deficiency exacerbated cardiac diastolic dysfunction induced by aging and in the HFpEF model. Conversely, Alpk2 overexpression increased the phosphorylation of tropomyosin 1, a major regulator that binds myosin to actin, and mitigated cardiac stiffness in HFpEF. This study provides novel evidence that ALPK2 represents a potential therapeutic target for cardiac diastolic dysfunction in HFpEF and age-related cardiac impairments.

Characterization of a novel ovine model of hypertensive heart failure with preserved ejection fraction.

The lack of animal models which accurately represent heart failure with preserved ejection fraction (HFpEF) has been a major barrier to the mechanistic understanding and development of effective therapies for this prevalent and debilitating syndrome characterized by multisystem impairments. Herein, we describe the development and characterization of a novel large animal model of HFpEF in older, female sheep with chronic 2-kidney, 1-clip hypertension. At six weeks post-unilateral renal artery clipping, hypertensive HFpEF sheep had higher mean arterial pressure compared to similarly aged ewes without unilateral renal artery clipping (mean arterial pressure = 112.7±15.9 vs 76.0±10.1 mmHg, P < 0.0001). The hypertensive HFpEF sheep were characterized by (i) echocardiographic evidence of diastolic dysfunction (lateral e' = 0.11±0.02 vs 0.14±0.04 m/s, P = 0.011; lateral E/e' = 4.25±0.77 vs 3.63±0.54, P = 0.028) and concentric left ventricular hypertrophy without overt systolic impairment, (ii) elevated directly measured left ventricular end-diastolic pressure (13±5 vs 0.5±1 mmHg, P = 2.1x10-6), and (iii) normal directly measured cardiac output. Crucially, these hypertensive HFpEF sheep had impaired exercise capacity as demonstrated by their (i) attenuated cardiac output (P = 0.001), (ii) augmented pulmonary capillary wedge pressure (P = 0.026), and (iii) attenuated hindlimb blood flow (P = 3.4x10-4) responses, during graded treadmill exercise testing. In addition, exercise renal blood flow responses were also altered. Collectively, our data indicates that this novel ovine model of HFpEF may be a useful translational research tool since it exhibits similar and clinically relevant impairments as that of HFpEF patients.

Abstract 4134456: Hybrid Cardiac Targeting Peptide Ameliorates HFpEF Phenotype in Mice

Introduction: Heart failure with preserved ejection fraction (HFpEF) is a form of heart failure which is rapidly rising in incidence in the US today. Despite this, no therapies with mortality benefit exist for this syndrome. Previous work with our novel hybrid cardiac targeting peptide (hCTP), a cardiomyocyte-specific cell penetrating peptide, has shown multiple beneficial biological effects (improved calcium handling, anti-inflammatory properties) beyond its transduction abilities. Therefore, we hypothesized that treatment with hCTP in a mouse model of HFpEF would ameliorate the pathophysiology of this disease. Methods: To establish a HFpEF model, 6-week-old, C57BL/6NJ mice were placed on a high-fat diet (HFD), 60% kCal from lard, and water with 0.5 g/L of an iNOS inhibitor (N-Nitro-L-arginine methylester) to induce hypertension. After 5 weeks of the diet, HFD mice and their littermate controls underwent baseline exercise testing and echocardiograms. Exercise capacity was measured after 2 days of exercise training with 2 days of rest in between; mice were placed on a treadmill at a 10-degree angle and made to run at increasingly fast speeds (5-30 m/min) until exhaustion. Echocardiograms were performed under 1.5% inhalational isoflurane. After baseline testing, the mice were treated with vehicle, or either 2.5 or 5 mg/Kg hCTP, either 3 or 5 days a week (five groups, n = 3 per group). After four weeks of treatment, the mice were again subjected to the same battery of tests and euthanized. Data was compared using two way ANOVA with Sidak’s test to compare measurements pre- and post-treatment. Results: Treatment with hCTP at either concentration for five days/week led to an increase in running distance from 39.8 m to 116.3 m (p = 0.03, n = 6), compared to changes in control distance from 208.4 m to 157.8 m (p = 0.399). Running distance did not correlate with weight (R 2 &lt; .001). Treatment with 5 mg/Kg hCTP for 5 days/week led to a normalization of the E/e’ ratio, from 43.3 to 26.9 (p = 0.004, n = 3) compared to a change in the control of 34.7 to 26.1 (p = 0.312). Ejection fractions remained consistent (&gt;55%) across all groups. Conclusions: Our data suggests that hCTP appears to be a promising treatment in ameliorating some of the physiological effects in a murine model of HFpEF. Gene and protein expression studies in heart tissue are underway. Further work is warranted with a larger sample size.

Abstract 4137688: Inhibition of Cardiac Fibrosis and Pro-Fibrotic Collagen Hormone Endotrophin by VS-041, a Novel Drug Candidate for Heart Failure with Preserved Ejection Fraction

Introduction: Endotrophin, a collagen type VI–derived signaling peptide, has been linked to cardiac metabolic dysregulation, inflammation, and fibrosis. Several matrix metalloproteinases (MMPs), incl. MMP2 and MMP9, have been shown to cleave collagen 6A3 and release endotrophin. Baseline plasma endotrophin levels in heart failure with preserved ejection fraction (HFpEF) patients were shown to be strongly and independently associated with increased risk of poor outcomes (death or HF-admissions). VS-041 is a novel drug candidate for HFpEF that inhibits key MMPs implicated in cardiac fibrosis and diastolic dysfunction. Previously, VS-041 demonstrated robust efficacy in the Dahl Salt Sensitive rat model of hypertension and HFpEF, improving diastolic function and dose-proportionally reducing left ventricle (LV) fibrosis. Hypothesis: Inhibition of endotrophin release by VS-041 could contribute to its anti-fibrotic mechanism and serve as a potential biomarker of MMP inhibition (target engagement) in patients. Methods and Results: The effect of VS-041 on production of endotrophin was investigated in a “Scar-in-a-Jar” model using primary human cardiac fibroblasts isolated from adult healthy ventricles. Fibroblasts were treated with 10 ng/mL platelet-derived growth factor (PDGF) AB in the presence of 0.03, 0.3, or 3 µM VS-041, or DMSO control. The concentration of endotrophin in the medium was assessed via the ELISA nordicPRO-C6 TM (Nordic Bioscience A/S). After 4 days of treatment, VS-041 at 0.3 µM and 3 µM significantly inhibited PDGF AB-stimulated production of endotrophin. Cumulative inhibitory effects of VS-041 could still be observed after 12 days of culture. The antifibrotic activity of VS-041 was also tested in a model of extensive cardiac fibrosis in 16-months old C57BL/6 mice exacerbated by angiotensin II infusion at 1 mg/kg/day for 28 days. Oral treatment with VS-041 at 75 mg/kg BID resulted in a 62% reduction (p&lt;0.01) of LV fibrosis as assessed by morphometry of Masson trichrome stained sections. VS-041 also improved the diastolic echocardiography parameters IVRT and E/a ratio. Conclusions: The production of endotrophin by fibroblasts is diminished by VS-041 and, therefore, its plasma levels could be explored as a biomarker of in vivo MMP inhibition by VS-041. Additionally, the inhibition of endotrophin release by VS-041 could be causatively linked to reduction of cardiac fibrosis and potentially translate into improved clinical outcomes in HFpEF patients.

Alarin regulates RyR2 and SERCA2 to improve cardiac function in heart failure with preserved ejection fraction.

Heart failure with preserved ejection fraction (HFpEF), a complex disease that is increasingly prevalent due to population aging, pose significant challenges in its treatment. The present study utilized the HFpEF rat model and H9C2 cells as research subjects to thoroughly investigate the potential mechanisms of alarin in protecting cardiac function in HFpEF. The study shows that under HFpEF conditions, oxidative stress significantly increases, leading to myocardial structural damage and dysfunction of calcium ion channels, which ultimately impairs diastolic function. Alarin, through its interaction with NADPH oxidase 1 (NOX1), effectively alleviates oxidative stress and modulates the activities of type 2 ryanodine receptor (RyR2) and sarcoplasmic/endoplasmic reticulum calcium ATPase 2 (SERCA2), thereby facilitating the restoration of Ca2+ homeostasis and significantly improving cardiac function in the HFpEF model. This research not only uncovers the cardioprotective effects of alarin and its underlying molecular mechanisms but also provides new insights and potential therapeutic targets for HFpEF treatment strategies, suggesting a promising future for alarin and related therapies in the management of this debilitating condition.

Pathobiological characterization of pulmonary hypertension associated with heart failure with preserved ejection fraction

Abstract Introduction Heart failure with preserved ejection fraction (HFpEF) is an age-related cardiometabolic disease associated with vascular inflammation in cardiac tissue, pulmonary congestion and right ventricular dysfunction. Patients with HFpEF often develop pulmonary hypertension (PH) and right ventricular (RV) hypertrophy. Pulmonary vascular remodeling contributes to combined post- and precapillary PH (CpcPH), which is associated with worse outcome in humans. A recently developed meta-inflammatory murine HFpEF model approximates the characteristics of human HFpEF. Herein, HFpEF is induced by metabolic (high-fat diet (HFD)) and hypertensive stress (inhibition of constitutive NO synthase by Nω-nitro-1-arginomethyl ester (L-NAME)) over a 12-week period of time. With a focus on PH, we have developed a 'three-hit' model based on this model with a supplementary 21- or 42-day hypoxia phase (HFpEF-CpcPH). Methods Adult C57BL/6N mice were fed HFD for 15 or 18 weeks and supplied with L-NAME (0,5g/L or 1g/L) via drinking water, including a final period of 21 or 42 days, respectively, of hypoxia (normobaric, 10 % oxygen) or normoxia. Transthoracic echocardiography was performed using a small animal ultrasound device (Vevo 3100, Visual Sonics) and measurement of right ventricular systolic pressure (RVSP) using a Millar® pressure catheter (Mil-SPR-1000) inserted into the right ventricle. Right ventricular hypertrophy was measured as the ratio of the wet weight of the right ventricle to the left ventricle including the septum (RV/LV+S). Results Administration of HFD and L-NAME had no significant effect on RVSP in either HFpEF-normoxia group (15 weeks (n=8) or 18 weeks (n=5)) compared to the control group (n=8, n=5). 21 days of hypoxia increased RV systolic pressure (RVSP) to 37.05±1.6 (PH, n=8) and 40.33±0.87 mmHg (HFpEF-CpcPH, n=8) respectively, while 42 days of hypoxia caused no further increase (35.1±3.5 mmHg (PH, n=5) and 35.24±3.47 mmgHg (HFpEF-CpcPH, n=4)), respectively. RV hypertrophy (RV/LV+S) was significantly increased after 21 days of hypoxia in HFpEF-CpcPH compared to HFpEF (n=8) (34.42±1.75 vs. 24.93±1.1). Again, 42 days of hypoxia did not lead to a further increase in RV hypertrophy (35.2±3.9 vs. 25.80±4.39) in HFpEF-CpcPH, even though there was a significant difference compared to the HFpEF group. As expected, the heart weight/body weight ratio was significantly increased in HFpEF-CpcPH compared to HFpEF at both time points. However, mice under the prolonged hypoxia phase showed a significantly greater decrease in body weight, which complicates the interpretation of the results. Conclusion In summary, we could show that in the meta-inflammatory HFpEF model no significant PH can be observed within the investigated periods of time. However, a 21 day hypoxia phase was sufficient to induce a HFpEF-CpcPH phenotype. This model provides an important basis to develop new therapeutic approaches.

Moderate intensity exercise training ameliorates the heart failure with preserved ejection fraction phenotype in a preclinical model by improving cardiometabolic fitness

Abstract Introduction and Aim Exercise intolerance is a hallmark feature of patients with heart failure with preserved ejection fraction (HFpEF).While clinical evidence suggests potential benefits of exercise training in HFpEF, its mechanisms remain largely unknown.In this study, we used a translationally relevant murine model of cardiometabolic HFpEF(1) to assess whether moderate intensity continuous training(MICT) can ameliorate the HFpEF phenotype in mice and promote cardiometabolic health. Methods Twenty-five adult, male C57BL/6N were fed with the combination of high fat diet(HFD;D12492,Research diet)and L-NAME(0.5 g/L,in drinking water) for 15 weeks to elicit HFpEF as previously described(1).After the establishment of the HFpEF phenotype, mice were randomized in two groups:sedentary(SED,n= 10) and exercised(MICT,n=15)mice.MICT was carried out according to the protocol:running on 10-degree positive inclination treadmill for 8 consecutive weeks,5 times/week,60 minutes/day,at a speed gradually increasing from 0.1 to 0.2 m/sec on a weekly basis.Morphometry, echocardiography(TTE),isoproterenol-induced stress echocardiography(SE),time domain nuclear magnetic resonance, and treadmill exhaustion tests were performed at the beginning and end of MICT.Additionally, at the end of MICT blood and tissues were collected for proteomics analysis(Fig1).Non-trained male C57BL/6N mice(37w) were used as controls for the HFpEF mice. Results Before randomization, all HFpEF mice were similar in terms of phenotypic characteristics. Compared to SED mice, MICT induced a significantly decrease in body weight driven by a reduction of total fat mass with an increased in lean mass(Fig2A+B).Interestingly, MICT had no impact on skeletal muscle mass for all different muscle groups evaluated (extensor digitorum longus, soleus and tibialis anterior).Importantly, MICT led to a significant improvement in exercise capacity in HFpEF mice, as shown by increased running distance and time, surpassing even the running distance seen in non-HFpEF mice (SED:62.8±18.7,MICT:305.7±13.9,non-HFpEF mice: 129.72±15.2meters,p&amp;lt;0.001).Preclinical surrogate of HFpEF such as pulmonary congestion, evaluated by index lung weights, improved after aerobic training.Following MICT there was a marked improvement in diastolic dysfunction(measured by E/E’ratio) both at rest(SED:36.5±3.3,MICT:23.3±5.09,p&amp;lt;0.001) and after isoproterenol challenge(SED:42.6±15.1,MICT:26.09±3.75,p&amp;lt;0.001)(Fig2C).Moreover, the wet cardiac mass was lower in the MICT group(Fig2A), suggesting potential amelioration in cardiac hypertrophy following aerobic training. Conclusion Eight weeks of supervised MICT on treadmill improves functional status, exercise capacity, and diastolic function in a cardiometabolic HFpEF murine model.The most significant effects were seen on weight loss and fat mass reduction.Our findings suggest a beneficial impact of aerobic exercise in mitigating HFpEF by improving metabolic fitness in the preclinical HFpEF model.Fig1-Study DesignFig2-Characteristics SED vs MICT groups

Diagnostic and prognostic evaluation of an echocardiography-based artificial intelligence algorithm for detecting HFpEF: a case-control analysis

Abstract Background Heart failure (HF) with preserved Ejection Fraction (HFpEF) is common among older adults and is associated with a high burden of morbidity and mortality. Despite its increasing prevalence, the diagnosis of HFpEF remains challenging. Recently, the FDA cleared an echocardiography-based AI HFpEF model that utilizes a 3-dimensional convolutional neural network to detect HFpEF using a single 4-chamber clip from a resting echocardiogram. However, the external validation of this algorithm against clinically adjudicated and confirmed HFpEF is limited. Purpose To evaluate the diagnostic and prognostic performance of the echocardiography-based AI HFpEF model in a cohort of HFpEF patients and matched controls. Methods The study included patients with clinically adjudicated HFpEF based on clinical history, normal ejection fraction (&amp;gt;45%), and evidence of elevated filling pressure by resting (PCWP &amp;gt; 15 mm Hg) or exercise invasive hemodynamics (PCWP &amp;gt; 25 mm Hg) or echocardiogram (E/e’ &amp;gt;14). The controls were age, sex, and BMI-matched patients without HF and a normal echocardiogram. The performance of the AI HFpEF model was evaluated using receiver operator curves. In patients with HFpEF, the association of the AI-HFpEF phenotype with elevated resting/exercise PCWP and peak exercise oxygen uptake (VO2peak) was assessed using multivariable logistic and linear regression models adjusting for age, sex, race, BMI, and comorbidities (diabetes, hypertension, kidney disease, atrial fibrillation). Results Of the 166 patients referred for evaluation of HFpEF, 82% had clinically adjudicated HFpEF, and 69.8% had elevated LV filling pressure at rest or exercise. In the matched cohorts of patients with clinically adjudicated HFpEF and matched control individuals (N = 122 each), the AI algorithm-based probability of HFpEF demonstrated good performance in identifying clinically adjudicated and hemodynamically confirmed HFpEF (AUROC: 0.75 for each) that was greater than the widely used H2FpEF score (0.69 and 0.70, Figure). In the HFpEF referral cohort, a higher probability of HFpEF based on the AI-algorithm phenotype was significantly associated with lower VO2peak (b [95% CI] per 5% higher probability: -0.11 [-0.21 to -0.01, P-value: 0.03] and greater odds of elevated PCWP (Odds ratio [95% CI] per 5% higher probability: 1.07 [1.01 – 1.15, P-value: 0.04] at rest or exercise after accounting for other confounders. Based on Youden’s index, the AI algorithm-based probability threshold of &amp;gt;0.75 was identified as the optimal cutoff for detecting HFpEF by the AI algorithm, with high sensitivity (0.85) and accuracy (0.74) and, adequate specificity (0.66). Conclusion The echocardiography-based AI HFpEF model demonstrated excellent sensitivity and discrimination in identifying patients with vs. without clinical HFpEF. Furthermore, the AI HFpEF model also had prognostic utility such that individuals with a higher probability of AI-HFpEF phenotype had more severe HFpEF.

Exosome-like nanovesicle targeting visceral adipose tissue inflammation mitigates heart failure with preserved ejection fraction

Abstract Introduction Heart failure (HF) with preserved ejection fraction (HFpEF) is associated with chronic systemic inflammation and obesity, with limited therapies. Inflammation in visceral adipose tissue (VAT) was significantly evoked in obese mice; while mesenchymal stem cell (MSC), especially atorvastatin (ATV)-pretreated MSC, could promote anti-inflammatory phenotype switch of immunocytes (e.g. macrophages), serving as a promising therapy for obesity-related HFpEF. Thus, the study was designed to prepare a novel ATV-pretreated MSC-derived exosome-like nanovesicles (ELNVs) and assess the anti-inflammatory and cardioprotective effects of ELNVs. Methods ELNVs derived from unpretreated MSC (ELNVM) or ATV-pretreated MSC (ELNVMA) were prepared and characterized (Figure 1). PKH-26-labelled ELNVs were incubated with THP1 cells for cell uptake assay. For anti-inflammatory studies in vitro, ELNVs (5×1010/mL) were added into the medium, followed by the induction of M1 or M2 polarization. The expressions of iNOS and Arg1 were measured by immunofluorescence (IF) staining. A 2-hit preclinical mice model of HFpEF, established by a 12-week high-fat diet (HFD) and Nω-Nitro-L-arginine methyl ester hydrochloride administration (0.5 g/L), was applied and received normal saline (NS) or ELNVs (i.p., 5×1011/kg body weight, 3 times a week). Functional and histological analysis including echocardiography, exhaustion test, WGA staining for hearts and western blot for VAT were performed. Quantitative polymerase chain reaction (qPCR) of key long non-coding RNAs (lncRNAs) was used to identify the mediator in ELNVs. Results The mean diameters of ELNVM and ELNVMA were 109.5 and 114.6 nm respectively and both ELNV types could be taken by THP1 cells. VAT inflammation was activated in HFpEF mice compared to the control in terms of the protein levels of iNOS and Arg1. An elevated expression of Arg1 and a decreased level of iNOS was observed in THP1 cells in vitro and VAT in vivo in both ELNV groups (P&amp;lt;0.05, Figure 1 and 2). Consistently, levels of interleukin (IL)-1β were increased in VAT of HFpEF mice, which were downregulated in ELNVM and ELNVMA groups. Both ELNVs could reduce the E/E’, and attenuate cardiac hypertrophy (heart weight to tibial length) and pulmonary congestion (lung weight [wet to dry]) (all P&amp;lt;0.05), with more pronounced improvements in ELNVMA group (Figure 2). Results of qPCR indicated three lncRNA candidates (TARID, H19 and KLF3-AS1) that were previously reported to inhibit M1 polarization or promote M2 polarization, were elevated in ELNVMA compared to ELNVM (P&amp;lt;0.05). Conclusion VAT inflammation was evoked in HFpEF mice and contributed to the development of HFpEF. This pilot study developed a novel ATV-pretreated ELNVs, which might serve as a promising tool for alleviating HFpEF due to the charming anti-inflammatory and cardioprotective effects mediated by regulating VAT macrophages.Figure 1.ELNVs’ PreparationFigure 2.Anti-inflammation of ELNVs

Obesity plays a key role in inducing myocardial and vascular dysfunction in a translational model of heart failure with preserved ejection fraction in rats

Abstract Background Exploring experimental models of heart failure with preserved ejection fraction (HFpEF) may help to understand the mechanisms leading to this challenging condition. Purpose In a translational model, we aimed to assess the relative contribution of hypertension and obesity in inducing structural, functional and hemodynamic changes associated to the HFpEF phenotype. Methods We investigated 3 groups of male 40 weeks old rats: control Wistar Kyoto (WKY, n=10), Spontaneous Hypertensive Rats (SHR, n=10) and SHR with obesity induced by consumption of cafeteria diet during 28 weeks (Ob-SHR, n=9). Animals were submitted to assessment of: body weight, systolic (SBP) and diastolic (DBP) blood pressure; in vivo structural and functional changes evaluated by high resolution Echocardiography including left atrial dimension (LA), left ventricle (LV) diastolic dimension (LVDD), LV posterior wall thickness (LVPW), LV wall relative thickness (LVWRT), LV ejection fraction (LVEF). Invasive hemodynamic evaluation assessed the intraventricular pressure curves obtaining LV end diastolic pressure (LVEDP) and calculation of LV diastolic time constant (Tau). After euthanasia, thoracic aorta was used for vascular function assessment by measuring the maximal cumulative concentration-effect curves of contraction to phenylephrine (PE), expressed as Emax (%). Protein expression of Intercellular Adhesion Molecule 1 (ICAM-1) was determined in myocardial tissue (% in relation to WKY). Results were expressed as mean ± SEM and effects of groups vs time were compared with mixed ANOVA. Results The results are shown in the table. We observed higher levels of SBP and DBP in SHR and Ob-SHR when compared to WKY, but with similar values between SHR and Ob-SHR groups. Regarding the structural LV changes, we observed LV remodeling and LA dilation in both SHR and Ob-SHR groups, but with no difference between both hypertensive groups. The Ob-SHR was the only group showing increased LVEDP in comparison to other groups. The Tau was also increased in the Ob-SHR animals. Concordantly, the Ob-SHR group showed increased expression of ICAM-1 (figure - A) that was concomitant to abnormal vascular response with increased contraction to PE (figure - B) as compared to SHR and WK groups. Conclusions In this translational model of HFpEF in rats, the structural changes related to LV remodeling were similar in SHR and Ob-SHR, probably reflecting comparable higher levels of blood pressure observed in both groups. In contrast, elevated EDP, a hallmark of HFpEF, was only seen in the Ob-SHR group and this was concomitant to diastolic dysfunction, endothelial inflammatory activation and altered vascular function. Our results indicate that obesity is a key factor inducing vascular and myocardial changes that triggers HFpEF phenotype in this model.

Characterization and progression of heart failure with preserved ejection fraction in SDT fatty rats

Abstract Background Heart failure with preserved ejection fraction (HFpEF) is a complex clinical phenotype associated with the presence of multiple comorbidities including diabetes, obesity, and metabolic syndrome. A major challenge in the search of new therapies for HFpEF is the development of relevant animal models. The Spontaneously Diabetic Torii (SDT) fatty rat is a well-established type2 diabetic model with multiple diabetes-related comorbidities such as nephropathy, neuropathy, and retinopathy. However, the onset and spontaneous progression of cardiac dysfunction is not yet reported in this model. Purpose To validate the SDT fatty rat as a type2 diabetes related HFpEF model, we assessed the natural evolution, i.e., without any diet or surgical intervention, of cardiac function in SDT fatty at different ages starting at 7-week of age. Methods The cardiovascular phenotyping of male SDT fatty rats was assessed by echocardiography at 7, 12 and 17-week of age and invasive left intraventricular and blood pressure measurements at 17-week of age. Vascular function of isolated thoracic aortas was also evaluated at 17-week of age. Renal function was investigated by measuring the Glomerular Filtration Rate (GFR) and urine parameters at 7, 12 and 17-week of age. A group of Sprague Dawley (SD) rats was included as a negative control. Results Compared to SD rats, echocardiography in SDT fatty showed cardiac remodeling starting at 7 weeks and persistent with age. Systolic function and ejection fraction were preserved, while diastolic function was impaired as early as 7-week of age and worsened with time. E/A was comparable in SDT fatty and SD rats at 7-week of age and then increased with age to reach 1.8±0.1 vs 1.2±0.05 in SD (p&amp;lt;0.001) at 17 weeks, while E’/A’ was already inverted at 7 weeks (0.9± 0.02 vs 1.3±0.03 in SD, p&amp;lt;0.001), and lasted with age which is a sign of relaxation default and suggestive of a restrictive filling pattern. E/E’ was significantly higher at 7-week of age (16.1± 0.9 vs 12.1±0.6 in SD, p&amp;lt;0.01) and further increased at 17 weeks (23.1± 0.8 vs 12.1±0.8 in SD, p&amp;lt;0.001) indicating higher filling pressure. Intraventricular and arterial pressure were also increased (p&amp;lt;0.05). As well, SDT fatty rats showed altered endothelium vasodilating properties. As expected, SDT fatty rats were hyperglycemic and showed renal impairment expressed by higher proteinuria, urine albumin/creatinine ratio, KIM-1 and cystatin-C levels and a hyperfiltration state (80% higher GFR, p&amp;lt;0.05). Conclusions The present data demonstrate that the SDT fatty rats developed diastolic dysfunction characterized by a restrictive profile combining compliance and relaxation impairments as well as higher filling pressure along with hypertension. This type2 diabetic model seems as a very promising model to translate the hypertension/kidney dysfunction and cardiometabolic clinical HFpEF phenogroups and is consequently a relevant model to evaluate drugs targeting HFpEF.

Cardiometabolic effects of sacubitril/valsartan in a rat model of heart failure with preserved ejection fraction

The promising results obtained in the PARADIGM-HF trial prompted the approval of sacubitril/valsartan (SAC/VAL) as a first-in-class treatment for heart failure with reduced ejection fraction (HFrEF) patients. The effect of SAC/VAL treatment was also studied in patients with heart failure with preserved ejection fraction (HFpEF) and, although improvements in New York Heart Association (NYHA) class, HF hospitalizations, and cardiovascular deaths were observed, these results were not so promising. However, the demand for HFpEF therapies led to the approval of SAC/VAL as an alternative treatment, although further studies are needed. We aimed to elucidate the effects of a 9-week SAC/VAL treatment in cardiac function and metabolism using a preclinical model of HFpEF, the Zucker Fatty and Spontaneously Hypertensive (ZSF1) rats. We found that SAC/VAL significantly improved diastolic function parameters and modulated respiratory quotient during exercise. Ex-vivo studies showed that SAC/VAL treatment significantly decreased heart, liver, spleen, and visceral fat weights; cardiac hypertrophy and percentage of fibrosis; lipid infiltration in liver and circulating levels of cholesterol and sodium. Moreover, SAC/VAL reduced glycerophospholipids, cholesterol, and cholesteryl esters while increasing triglyceride levels in cardiac tissue. In conclusion, SAC/VAL treatment improved diastolic and hepatic function, respiratory metabolism, reduced hypercholesterolemia and cardiac fibrosis and hypertrophy, and was able to modulate cardiac metabolic profile. Our findings might provide further insight into the therapeutic benefits of SAC/VAL treatment in obese patients with HFpEF.

PDE9A Inhibition Improves Coronary Microvascular Rarefaction and Left Ventricular Diastolic Dysfunction in the ZSF1 Rat Model of HFpEF.

Heart failure with preserved ejection fraction (HFpEF) commonly arises from comorbid diseases, such as hypertension, obesity, and diabetes mellitus. Selective inhibition of phosphodiesterase 9A (PDE9A) has emerged as a potential therapeutic approach for treating cardiometabolic diseases. Coronary microvascular disease (CMD) is one of the key mechanisms contributing to the development of left ventricular (LV) diastolic dysfunction in HFpEF. Our study aimed to investigate the mechanisms by which PDE9A inhibition could ameliorate CMD and improve LV diastolic function in HFpEF. The obese diabetic Zucker fatty/spontaneously hypertensive heart failure F1 hybrid (ZSF1) rat model of HFpEF was employed in which it was found that a progressively developing coronary microvascular rarefaction is associated with LV diastolic dysfunction when compared to lean, nondiabetic hypertensive controls. Obese ZSF1 rats had an increased cardiac expression of PDE9A. Treatment of obese ZSF1 rats with the selective PDE9A inhibitor, PF04447943 (3 mg/kg/day, oral gavage for 2 weeks), improved coronary microvascular rarefaction and LV diastolic dysfunction, which was accompanied by reduced levels of oxidative and nitrosative stress markers, hydrogen peroxide, and 3-nitrotyrosine. Liquid chromatography-mass spectrometry (LC-MS) proteomic analysis identified peroxiredoxins (PRDX) as downregulated antioxidants in the heart of obese ZSF1 rats, whereas Western immunoblots showed that the protein level of PRDX5 was significantly increased by the PF04447943 treatment. Thus, in the ZSF1 rat model of human HFpEF, PDE9A inhibition improves coronary vascular rarefaction and LV diastolic dysfunction, demonstrating the usefulness of PDE9A inhibitors in ameliorating CMD and LV diastolic dysfunction through augmenting PRDX-dependent antioxidant mechanisms.

Abstract P119: The Heart Failure with Preserved Ejection Fraction Induced By High-Fat Diet and L-NAME in Mice Does not Induce a Renal Damage

Heart failure with preserved ejection fraction (HFpEF) is a clinical syndrome, without effective therapy, characterized by diastolic dysfunction, a chronic low-grade inflammation and comorbidities such as hypertension. At the present time, few experimental models of HFpEF represent the hallmarks of patients. Recently, it has been described that the administration of a high-fat diet (HFD) in conjunction with an endothelial nitric oxide synthase inhibitor (L-NAME) can adequately reproduce the pathophysiological features of HFpEF. However, the effects on at renal level in HFpEF models have not been fully described. Our goal was to evaluate the kidney damage in a HFpEF model induced by HFD+L-NAME. Male C57BL/6N mice (12 weeks old, n=4-6) were treated with control diet or HFD (60% in fat calories) plus L-NAME (0.65 g/L in drinking water) for 15 weeks. We evaluated cardiac function (echocardiographic analysis), systolic blood pressure (SBP, plethysmography), cardiac and renal hypertrophy (morphometry and histology), plasma creatinine, blood urea nitrogen (BUN), plasma neutrophil gelatinase-associated lipocalin (pNGAL), proteinuria, and kidney immune cells infiltration (flow cytometry). All data are presented by mean±standard deviation. After 15 weeks of HFD+L-NAME we observed diastolic dysfunction (p&lt;0.001), an increased SBP (control=128.0±15.3 vs. HFD+L-NAME=155.7±9.8 mmHg; p&lt;0.01), without changes in ejection fraction and shortening fraction. In addition, we did not observe cardiac or renal hypertrophy, nor apparent histological changes in the renal structure between both groups of animals. No differences were found between groups regarding plasma creatinine, pNGAL or BUN, however, we observed that HFD+L-NAME induced proteinuria in compared to control mice (p&lt;0.05). Finally, when we evaluated the immune cells population in kidney of both groups, we observed no differences in dendritic cells, macrophages, or neutrophils. Nevertheless, the HFD+L-NAME treatment was associated to a significant rising of Ly6G + CD11b - cells population (CD45 + MHC-II - CD11c +/- F4/80 - ) compared to control mice (p&lt;0.05). In conclusion, our results indicate that there is no renal inflammatory damage after 15 weeks of in HFpEF experimental model. However, to our knowledge, an uncharacterized population of Ly6G cells could be participating at this stage which could trigger a long-term renal damage . FONDECYT 1221585 (MPO), 1231604 (JJ), 1231909 (CAA), 11241074 (PA) and FONDAP 15130011(MPO, LG).

Repeat administration of human umbilical cord mesenchymal stem cells improves left ventricular diastolic function in mice with heart failure with preserved ejection fraction

Currently, no therapy is proven to effectively improve heart failure with preserved ejection fraction (HFpEF). Although stem cell therapy has demonstrated promising results in treating ischemic heart disease, the effectiveness of treating HFpEF with human umbilical cord mesenchymal stem cells (hucMSCs) remains unclear. To answer this question, we administered hucMSCs intravenously (i.v.), either once or repetitively, in a mouse model of HFpEF induced by a high-fat diet and NG-nitroarginine methyl ester hydrochloride. hucMSC treatment improved left ventricular diastolic dysfunction, reduced heart weight and pulmonary edema, and attenuated cardiac modeling (inflammation, interstitial fibrosis, and hypertrophy) in HFpEF mice. Repeat hucMSC administration had better outcomes than a single injection. In vitro, hucMSC culture supernatants reduced maladaptive remodeling in neonatal-rat cardiomyocytes. Ribonucleic acid sequencing and protein level analysis of left ventricle (LV) tissues suggested that hucMSCs activated the protein kinase B (Akt)/forkhead box protein O1 (FoxO1) signaling pathway to treat HFpEF. Inhibition of this pathway reversed the efficacy of hucMSC treatment. In conclusion, these findings indicated that hucMSCs could be a viable therapeutic option for HFpEF.

Abstract Mo103: Aberrant Trans- and De- Nitrosylation Underpins Nitrosative Stress in Cardiometabolic HFpEF

Background: Heart failure with preserved ejection fraction (HFpEF) is among the leading causes of cardiovascular mortality and morbidity. Recent reports suggest excessive myocardial protein S-nitrosylation (-SNO), a hallmark of nitrosative stress, contributes to HFpEF pathophysiology. However, the role of transnitrosylases, enzymes that induce protein-SNO, or denitrosylases, enzymes that eliminate protein-SNO, have not been investigated in the context of HFpEF. Research Questions and Goals: We sought to investigate the regulation of protein nitrosylation dynamics in a rat model of cardiometabolic HFpEF. Methods: Echocardiographic assessment, invasive hemodynamic measurements, and exercise testing were conducted in WKY or ZSF1 obese (Ob) rats to evaluate HFpEF severity. Nitric oxide (NO) bioavailability and protein-SNO levels were determined in the heart tissue. Endothelial-dependent vascular reactivity was assayed to further evaluate NO signaling. In parallel, single-cell (sc) RNA sequencing was performed to determine the transcriptional changes in trans- and denitrosylases, as well as NO synthases. Results: We observed progressive deterioration in LV diastolic function (significantly elevated E/e’ and LV end-diastolic pressure) and exercise performance in ZSF1 Ob when compared to WKY controls. Notably, ZSF1 Ob rats exhibited an age-dependent elevation in protein-SNO levels, despite significant reduction in NO bioavailability and signaling. Targeted sc transcriptomic analysis revealed significantly elevated expression of transnitrosylases such as hemoglobin subunit α and β in cardiomyocytes, endothelial cells, and cardiac fibroblasts from ZSF1 Ob hearts. In contrast, significantly reduced expression of denitrosylases such as thioredoxin 2 was found in the ZSF1 Ob cardiomyocytes. No change was observed in expression of NO synthases (nNOS, iNOS, eNOS). Conclusion: Herein, we demonstrate a profound disconnect between insufficient NO bioavailability and nitrosative stress in ZSF1 Ob rat model of HFpEF. Our data suggests the pathological accumulation of nitroso - proteins, may be attributed in part to the derangement of transnitrosylases and denitrosylases expression. Restoration of physiological protein nitrosylation dynamics may represent a novel therapeutic approach for HFpEF, and warrants further investigation.

Abstract Mo102: Swine Model of Heart Failure with Preserved Ejection Fraction Driven by Lipoprotein Lipase Inhibition and Enhanced Cardiac Low-Density Lipoprotein Receptor Expression

Background: Heart failure with preserved ejection fraction (HFpEF) poses an escalating public health threat, marked by growing incidence and high mortality. In the cardiometabolic phenogroup of HFpEF that includes diabetes and obesity, intramyocardial lipid content is a prognostic indicator of diastolic dysfunction and adverse outcome. Our group recently reported a mouse model of cardiometabolic HFpEF wherein myocardial lipotoxicity was induced by systemic inhibition of lipoprotein lipase (LPL) with Poloxamer 407 (P407) and cardiac overexpression of the LDL receptor (LDLR), conditions that have been documented in clinical HFpEF. The model demonstrates myocardial lipid accumulation, fibrosis, arrhythmia, and diastolic dysfunction. To reproduce this model in large animals we implemented the same protocol in pigs. Methods: Female Yorkshire swine (~25 Kg) were subjected to one of two protocols including: 1) single intracoronary (i.c.) injection of 10 13 AAV9-cTnT-LDLR particles and biweekly intraperitoneal (i.p.) P407 at 1g/Kg, (high dose, n=2), or 2) Double i.c. injections of 10 13 AAV9-cTnT-LDLR particles and biweekly i.p. P407 at 0.25g/Kg) (low dose, n=2). Cardiac structure and function were evaluated by MRI, and hemodynamics measured by PV-Loop at baseline, 4, 8, and 12 weeks. Blood was collected biweekly for complete blood count (CBC), basic biochemistry, and liver and lipid panels. Tissues were collected for protein and histopathological analysis. Results: In both strategies, the animals developed high LDL-cholesterol and cardiac hypertrophy with preserved EF. High dose P407 led to higher triglycerides, VLDL, HDL, liver injury (ALT &gt; 200U/L), and steatosis at 4 weeks. One of the 2 pigs died at 3 weeks. Low dose P407 and high dose viral particles induced HFpEF at ~12 weeks with increased LV mass, relative wall thickness, end-diastolic pressure, and tau. Serum LDL-C accumulated from an initial value of 161 to 344.5mg/dL at 12 weeks. No significant liver injury was present until week 12 (ALT&lt;88 U/L, AST&lt;59 U/L). Both strategies did not exhibit abnormalities in CBC or other biochemical parameters. Conclusions: Low dose inhibition of LPL combined with cardiac overexpression of LDLR confers HFpEF in swine.

Abstract Mo101: 3-Mercaptopyruvate Sulfurtransferase is a Critical Regulator of Branched-Chain Amino Acid Catabolism in Cardiometabolic HFpEF

Background: Heart failure with preserved ejection fraction (HFpEF) is among the leading causes of cardiovascular mortality and morbidity. Recent multi-omics data sets underscore severely impaired branched-chain amino acid (BCAA) catabolism in the failing hearts of HFpEF patients. 3-mercaptopyruvate sulfurtransferase (3-MST) is a mitochondrial hydrogen sulfide (H 2 S) synthase that regulates mitochondrial biogenesis, function, and substrate metabolism. Research Questions and Goals: In the current study, we aimed to elucidate the role of 3-MST in myocardial BCAA catabolism in cardiometabolic HFpEF. Methods: 3-MST knockout or wild-type (WT) mice were subjected to control or L-NAME and high fat diet - induced HFpEF. Echocardiographic measurements, invasive hemodynamic assessment, and exercise capacity testing were conducted to determine HFpEF severity. Metabolomic analysis was performed to study BCAA catabolism. Additionally, a H 2 S donor, SG1002 was administered to increase H 2 S bioavailability in the setting of 3-MST deficiency and HFpEF. Results: We observed progressive deterioration in left ventricular (LV) diastolic function and exercise performance from mice subjected to HFpEF. Genetic ablation of 3-MST further-exacerbated HFpEF severity as evidenced by significantly increased E/e’ ratio, elevated LV end-diastolic pressure, and reduced exercise performance. Metabolomic analysis revealed pathological accumulation of intermediate metabolites of BCAA in the HFpEF hearts, suggesting a major derangement in myocardial BCAA catabolism. 3-MST KO hearts exhibited further BCAA catabolic defects as compared to those from WT. Importantly, H 2 S donor treatment significantly attenuated BCAA catabolic defect and alleviated HFpEF severity in both WT and 3-MST KO HFpEF mice. Conclusion: Our results demonstrate that deficiency of 3-MST impairs myocardial BCAA catabolism, which results in exacerbated HFpEF severity in a “two-Hit” mouse model of HFpEF. These data suggest 3-MST is critically involved in physiological substrate metabolism within the mitochondria and exerts beneficial effects in HFpEF. Future experiments are underway to delineate the mechanisms by which 3-MST regulates BCAA catabolism.