Abstract 988: Tissue Inhibitor Of Metalloproteinase-3 Regulates Myocardial Fibrosis By Regulating The TGFβ-TNF Interaction

Fibrosis is the outcome of excess deposition of extracellular matrix components and underlies diastolic and systolic heart failure. Metalloproteinases (MMPs and ADAMs) and their inhibitors (TIMPs) are critical regulators of ECM turnover and fibrosis. TIMP3 is a potent inhibitor of MMPs and ADAMs, whereby it regulates tissue proteolysis and cytokine bioavailability. TIMP3 levels are reduced in human heart disease, and we found that mice lacking Timp3 (KO) exhibit severe dilated cardiomyopathy (DCM), extensive interstitial fibrosis and early heart failure (HF) following pressure overload compared to wild type (WT) mice. We showed upregulated TNF signaling within 6 hrs of aortic banding (AB) which when blocked, significantly improved DCM and prevented HF. We then investigated the mechanism underlying the extensive fibrosis despite the increased MMP activity in the TIMP3KO mice. Comparative microarray analyses show a significant upregulation of the TGFβ1 signaling pathway within 6 hrs of AB in KO vs WT hearts. In vivo treatment of KO-AB mice with a TGFβ1-neutralizing antibody (1D11) completely abolishes fibrosis, markedly improves left ventricular dilation, systolic and diastolic heart function (LVEDD(mm): 4.3 ± 0.1 in WT, 5.4 ± 0.1 in KO, 4.7 ± 0.1 in KO+ 1D11; fractional shortening(%): 40.2 ± 1.7 in WT, 19.6 ± 2.2 in KO, 36.2 ± 0.7 in KO+ 1D11; E/Ac ratio: 2.5 ± 0.3 in WT, 1.8 ± 0.3 in KO, 2.4 ± 0.2 in KO + 1D11; n = 22, P < 0.05). Interestingly, blocking TGFβ1 also prevented the early rise in TNF in KO hearts. Using primary neonatal culture systems, we found that cardiomyocyte-fibroblast interaction is essential for a fibrotic response to agonists (Ang II, PE). Further, KO co-cultures generate a 5-fold greater fibrosis (P < 0.05) through activation of Smad2/3 pathway compared to WT. TGFβ also regulates TNF transcription more potently in KO cells since a 3-fold higher TNF induction occurred in response to recombinant TGFβ1 in KO vs WT co-cultures (P < 0.05). In conclusion, TIMP3 is a critical regulator of TGFβ1 and TNF, and its deficiency induces parallel dysregulations in the signaling of these cytokines very early after pressure overload, leading to severe interstitial fibrosis and DCM, hence, TIMP3-based therapies can simultaneously impact fibrosis and DCM.

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Abstract 278: Domain-specific Roles for GRK2 in Cardiac Hypertrophy and Heart Failure

Circulation Research ◽

10.1161/res.119.suppl_1.278 ◽

2016 ◽

Vol 119 (suppl_1) ◽

Author(s):

Sarah M Schumacher ◽

Erhe Gao ◽

J. Kurt Chuprun ◽

Walter J. Koch

Keyword(s):

Heart Failure ◽

Interstitial Fibrosis ◽

Heart Function ◽

Pressure Overload ◽

Left Ventricular ◽

Cross Sectional ◽

Amino Terminal ◽

Domain Specific ◽

Rgs Domain

During heart failure (HF), cardiac levels and activity of the G protein-coupled receptor (GPCR) kinase (GRK) GRK2 are elevated and contribute to adverse remodeling and contractile dysfunction, while inhibition via a carboxyl-terminal peptide, βARKct, enhances heart function and can prevent HF. Mounting evidence supports the idea of a dynamic “interactome” in which GRK2 can uncouple GPCRs via novel protein-protein interactions. Several GRK2 interacting partners are important for adaptive and maladaptive myocyte growth; therefore, an understanding of domain-specific interactions with signaling and regulatory molecules could lead to novel targets for HF therapy. For instance, GRK2 contains a putative amino-terminal R egulator of G protein S ignaling (RGS) domain (βARKrgs) that directly interacts with Gαq and inhibits signaling. Previously, our lab investigated cardiac-specific transgenic expression of a fragment of this RGS domain (βARKnt), that did not reduce acute hypertrophy after pressure overload or demonstrate RGS activity in vivo against Gαq-mediated signaling. In contrast, βARKnt induced hypertrophy and elevated β-adrenergic receptor (βAR) density without altering agonist-induced contractility or adenylyl cyclase activity, due to a compensatory increase in GRK2 activity. Importantly, βAR downregulation in response to chronic agonist administration was attenuated by βARKnt expression, indicating a novel regulation of βAR receptor density. Herein, we investigated the effect of βARKnt expression during chronic pressure overload post trans-aortic constriction (TAC). Echocardiographic analysis revealed increased posterior wall thickness and left-ventricular mass 4 weeks post-TAC compared to non-transgenic littermate controls. Importantly, despite enhanced hypertrophy, the progression to HF was inhibited in βARKnt mice 14 weeks post-TAC. Histological analysis of interstitial fibrosis and cross-sectional area is underway to determine alterations in maladaptive remodeling. Further, cardiomyocyte signaling and βARKnt protein-binding partners are a focus, since our data indicate that βARKnt-mediated regulation of βAR density may provide a novel means of cardioprotection during pressure-overload induced HF.

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Abstract 365: Domain-specific Roles for GRK2 in Cardiac Hypertrophy and Heart Failure

Circulation Research ◽

10.1161/res.117.suppl_1.365 ◽

2015 ◽

Vol 117 (suppl_1) ◽

Author(s):

Sarah M Schumacher ◽

Erhe Gao ◽

J. Kurt Chuprun ◽

Walter J Koch

Keyword(s):

Heart Failure ◽

G Protein ◽

Protein Interactions ◽

Heart Function ◽

Pressure Overload ◽

Left Ventricular ◽

Amino Terminal ◽

Domain Specific ◽

Rgs Domain

During heart failure (HF), cardiac levels and activity of the G protein-coupled receptor (GPCR) kinase (GRK) GRK2 are elevated and contribute to adverse remodeling and contractile dysfunction, while inhibition via a carboxyl-terminal peptide, βARKct, enhances heart function and can prevent HF development. Mounting evidence supports the idea of a dynamic “interactome” in which GRK2 can uncouple GPCRs via novel protein-protein interactions. Several GRK2 interacting partners are important for adaptive and maladaptive myocyte growth; therefore, an understanding of domain-specific interactions with signaling and regulatory molecules could lead to novel targets for HF therapy. For instance, GRK2 contains a putative amino-terminal Regulator of G protein Signaling (RGS) domain (βARK-RGS) that directly interacts with Gq and appears to inhibit signaling without altering Gq enzymatic activity. Previously, our lab investigated cardiac-specific transgenic (Tg) expression of a fragment of this RGS domain (βARKnt). This fragment did not alter acute hypertrophy after pressure overload or demonstrate RGS activity in vivo against Gq-mediated signaling. In contrast, βARKnt induced hypertrophy and elevated β-adrenergic receptor (βAR) density without altering agonist-induced contractility or adenylyl cyclase activity, due to a compensatory increase in GRK2 activity. Importantly, though, βAR downregulation in response to chronic agonist administration was attenuated by βARKnt expression, indicating a novel regulation of βAR receptor density. Given these findings we have recently investigated the effect of βARKnt expression during chronic pressure overload post trans-aortic constriction (TAC). Echocardiographic analysis revealed increased posterior wall thickness and left-ventricular mass 4 weeks post-TAC compared to non-transgenic littermate controls (NLC). Importantly, despite enhanced hypertrophy, the progression to HF was inhibited in βARKnt mice 14 weeks post-TAC (%LV Ejection Fraction of 36.1 ± 0.2 in NLC versus 56.6 ± 0.9 in Tg mice). While mechanistic characterization is underway, these data indicate that βARKnt-mediated regulation of βAR density may provide a novel means of cardioprotection during pressure-overload induced HF.

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Abstract 285: Cardiac Inflammation and Fibrosis Induced by Heart Failure Are Reversed by Short-Duration Estrogen Therapy

Circulation Research ◽

10.1161/res.111.suppl_1.a285 ◽

2012 ◽

Vol 111 (suppl_1) ◽

Author(s):

Andrea Iorga ◽

Rangarajan Nadadur ◽

Salil Sharma ◽

Jingyuan Li ◽

Mansoureh Eghbali

Keyword(s):

Heart Failure ◽

Estrogen Therapy ◽

Pressure Overload ◽

Decompensated Heart Failure ◽

Left Ventricular ◽

Neonatal Rat ◽

In Vivo Model ◽

Anti Inflammatory

Heart failure is generally characterized by increased fibrosis and inflammation, which leads to functional and contractile defects. We have previously shown that short-term estrogen (E2) treatment can rescue pressure overload-induced decompensated heart failure (HF) in mice. Here, we investigate the anti-inflammatory and anti-fibrotic effects of E2 on reversing the adverse remodeling of the left ventricle which occurs during the progression to heart failure. Trans-aortic constriction procedure was used to induce HF. Once the ejection fraction reached ∼30%, one group of mice was sacrificed and the other group was treated with E2 (30 αg/kg/day) for 10 days. In vitro, co-cultured neonatal rat ventricular myocytes and fibroblasts were treated with Angiotensin II (AngII) to simulate cardiac stress, both in the presence or absence of E2. In vivo RT-PCR showed that the transcript levels of the pro-fibrotic markers Collagen I, TGFβ, Fibrosin 1 (FBRS) and Lysil Oxidase (LOX) were significantly upregulated in HF (from 1.00±0.16 to 1.83±0.11 for Collagen 1, 1±0.86 to 4.33±0.59 for TGFβ, 1±0.52 to 3.61±0.22 for FBRS and 1.00±0.33 to 2.88±0.32 for LOX) and were reduced with E2 treatment to levels similar to CTRL. E2 also restored in vitro AngII-induced upregulation of LOX, TGFβ and Collagen 1 (LOX:1±0.23 in CTRL, 6.87±0.26 in AngII and 2.80±1.5 in AngII+E2; TGFβ: 1±0.08 in CTRL, 3.30±0.25 in AngII and 1.59±0.21 in AngII+E2; Collagen 1: 1±0.05 in CTRL.2±0.01 in AngII and 0.65±0.02 (p<0.05, values normalized to CTRL)). Furthermore, the pro-inflammatory interleukins IL-1β and IL-6 were upregulated from 1±0.19 to 1.90±0.09 and 1±0.30 to 5.29±0.77 in the in vivo model of HF, respectively, and reversed to CTRL levels with E2 therapy. In vitro, IL-1β was also significantly increased ∼ 4 fold from 1±0.63 in CTRL to 3.86±0.14 with AngII treatment and restored to 1.29±0.77 with Ang+E2 treatment. Lastly, the anti-inflammatory interleukin IL-10 was downregulated from 1.00±0.17 to 0.49±0.03 in HF and reversed to 0.67±0.09 in vivo with E2 therapy (all values normalized to CTRL). This data strongly suggests that one of the mechanisms for the beneficial action of estrogen on left ventricular heart failure is through reversal of inflammation and fibrosis.

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Abstract 744: Arrhythmogenesis in Heart Failure: Role of Interstitial Fibrosis

Circulation ◽

10.1161/circ.116.suppl_16.ii_141 ◽

2007 ◽

Vol 116 (suppl_16) ◽

Author(s):

Jorge E Massare ◽

R. Haris Naseem ◽

Jeff M Berry ◽

Farhana Rob ◽

Joseph A Hill

Keyword(s):

Heart Failure ◽

Interstitial Fibrosis ◽

Systolic Dysfunction ◽

Ventricular Tachyarrhythmia ◽

Severe Heart Failure ◽

Pressure Overload ◽

Cellular Events ◽

Action Potential Prolongation

Background: Sudden cardiac death due to ventricular tachyarrhythmia (VT) accounts for a large number of deaths in patients with heart failure. Several cellular events which occur during pathological remodeling of the failing ventricle are implicated in the genesis of VT, including action potential prolongation, dysregulation of intercellular coupling, and fibrosis. Interestingly, transgenic mice over-expressing constitutively active PKD (caPKD) develop severe heart failure without interstitial fibrosis, an otherwise prominent feature of the disease. The goal here was to define the role of interstitial fibrosis in the proarrhythmic phenotype of failing myocardium. Methods and Results: We performed echocardiographic, electrocardiographic, and in vivo electrophysiologic studies in 8 –10 week old caPKD mice (n=12). Similar studies were performed in mice with load-induced heart failure induced by surgical pressure overload (sTAB, n=10), a model of heart failure with prominent interstitial fibrosis. caPKD and sTAB mice showed similar degrees of ventricular dilation (LV systolic dimension caPKD 2.4±0.8 mm vs 3.0±0.9 sTAB, p=0.18) and severe systolic dysfunction (% fractional shortening caPKD 25±11 vs 28±11 sTAB, p=0.62). Yet, caPKD mice showed minimal interstitial fibrosis, comparable to unoperated controls. With the exception of ventricular refractory period, which was higher in caPKD (48±11 msec vs 36±7 TAB and 40±8 WT, p<0.05), other electrocardiographic and electrophysiologic variables were similar among the 3 groups (p=NS), including heart rate, QT duration, and mean VT threshold. As expected, VT (≥3beats) was readily inducible by programmed stimulation in sTAB mice (7/10). By contrast, VT was less inducible in caPKD mice (4/12; p=0.1 vs TAB and <0.05 vs WT), and uninducible in unoperated controls (0/12). VT was polymorphic in both models, but episodes of VT were both slower (VT cycle length caPKD 58±4.0 msec vs 48±1 sTAB, p=0.016) and longer in caPKD mice (caPKD 1.8±0.7 sec vs 0.47±0.3 sTAB, p=0.038). Conclusion: Interstitial fibrosis contributes to the inducibility, maintenance, and rate of VT in heart failure. These findings highlight the importance of anti-remodeling therapies known to target fibrosis in heart disease.

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Chronic interval exercise training prevents BKCa channel-mediated coronary vascular dysfunction in aortic-banded miniswine

Journal of Applied Physiology ◽

10.1152/japplphysiol.01138.2017 ◽

2018 ◽

Vol 125 (1) ◽

pp. 86-96 ◽

Cited By ~ 8

Author(s):

T. Dylan Olver ◽

Jenna C. Edwards ◽

Brian S. Ferguson ◽

Jessica A. Hiemstra ◽

Pamela K. Thorne ◽

...

Keyword(s):

Heart Failure ◽

Exercise Training ◽

Ejection Fraction ◽

Vascular Dysfunction ◽

Pressure Overload ◽

Left Ventricular ◽

Preserved Ejection Fraction ◽

Interval Exercise

Conventional treatments have failed to improve the prognosis of heart failure with preserved ejection fraction (HFpEF) patients. Thus, the purpose of this study was to determine the therapeutic efficacy of chronic interval exercise training (IT) on large-conductance Ca2+-activated K+ (BKCa) channel-mediated coronary vascular function in heart failure. We hypothesized that chronic interval exercise training would attenuate pressure overload-induced impairments to coronary BKCa channel-mediated function. A translational large-animal model with cardiac features of HFpEF was used to test this hypothesis. Specifically, male Yucatan miniswine were divided into three groups ( n = 7/group): control (CON), aortic banded (AB)-heart failure (HF), and AB-interval trained (HF-IT). Coronary blood flow, vascular conductance, and vasodilatory capacity were measured after administration of the BKCa channel agonist NS-1619 both in vivo and in vitro in the left anterior descending coronary artery and isolated coronary arterioles, respectively. Skeletal muscle citrate synthase activity was decreased and left ventricular brain natriuretic peptide levels increased in HF vs. CON and HF-IT animals. A parallel decrease in NS-1619-dependent coronary vasodilatory reserve in vivo and isolated coronary arteriole vasodilatory responsiveness in vitro were observed in HF animals compared with CON, which was prevented in the HF-IT group. Although exercise training prevented BKCa channel-mediated coronary vascular dysfunction, it did not change BKCa channel α-subunit mRNA, protein, or cellular location (i.e., membrane vs. cytoplasm). In conclusion, these results demonstrate the viability of chronic interval exercise training as a therapy for central and peripheral adaptations of experimental heart failure, including BKCa channel-mediated coronary vascular dysfunction. NEW & NOTEWORTHY Conventional treatments have failed to improve the prognosis of heart failure with preserved ejection fraction (HFpEF) patients. Our findings show that chronic interval exercise training can prevent BKCa channel-mediated coronary vascular dysfunction in a translational swine model of chronic pressure overload-induced heart failure with relevance to human HFpEF.

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P1614Soluble guanylate cyclase as a therapeutic target in heart failure: myocardial gene expression in response to sGC stimulation in pressure overload

European Heart Journal ◽

10.1093/eurheartj/ehz748.0373 ◽

2019 ◽

Vol 40 (Supplement_1) ◽

Author(s):

J Ruedebusch ◽

A Benkner ◽

N Nath ◽

L Kaderali ◽

K Klingel ◽

...

Keyword(s):

Gene Expression ◽

Heart Failure ◽

Cardiac Hypertrophy ◽

Expression Pattern ◽

Heart Function ◽

Gene Expression Pattern ◽

Pressure Overload ◽

Left Ventricular ◽

Marker Genes ◽

Cgmp Pathway

Abstract Background Heart Failure (HF) is associated with endothelial dysfunction and reduced bioavailability of NO with insufficient stimulation of sGC and reduced production of cGMP. Therefore, the impairment of the NO-sGC-cGMP pathway results in vasoconstriction, platelet aggregation, inflammation, fibrosis and most importantly maladaptive cardiac hypertrophy. The restoration of the NO-sGC -cGMP pathway is an attractive pharmacological target for HF therapy. Purpose Riociguat is an NO independent stimulator of the sGC that sensitizes the sGC to endogenous NO and directly stimulates sGC to produce cGMP. We therefore hypothesized that Riociguat prevents pathological effects occurring during HF. Methods Pressure overload was induced by transverse aortic constriction (TAC) in 8 weeks old male C57Bl6/N mice. Three weeks after TAC when cardiac hypertrophy has developed either Riociguat (RIO; 3 mg/kg) or a Solvent was administered daily for 5 more weeks (n=12 per group). Animals with sham surgery and same drug regime served as controls. The heart function in all groups was evaluated weekly by small animal echocardiography. Eight weeks after surgery, the transcriptome of the left ventricles (LV) of sham and TAC mice were analysed by RNA Sequencing. Differentially expressed genes (DEG) were categorised using Ingenuity Pathway Analysis (IPA). Results TAC resulted in a steady decrease of left ventricular fractional shortening (FS) in the mice until week 3. When Riociguat treatment commenced, the systolic LV function of the TAC+Rio group recovered significantly whereas the solvent group showed a further decline until week 8 (FS 21.4±3.4% vs. 9.5±2%, p<0.001). Both sham groups (Sham+Sol and Sham+Rio) showed no changes in the heart function over timer. Regarding the hypertrophic response to LV pressure overload, Riociguat treatment attenuated significantly the increase of the left ventricular mass (LVM 208.3±15.8mg vs. 148.9±11.8mg, p<0.001) after TAC. In line with the reduced LVM, histological staining showed a significantly reduced fibrosis and myocyte cross sectional area in the TAC+Rio group compared to TAC+Sol group. Regarding the myocardial transcriptome, the treatment with Riociguat resulted in less changes of gene expression pattern after TAC (TAC+Sol vs. Sham+Sol 3160 DEG; TAC+Rio vs. Sham+Rio 2237 DEG). The expression of heart failure marker genes like ANP (Nppa), BNP (Nppb), β-Myosin Heavy Chain (Myh7) and the Collagens 1 and 3 (Col1a1, Col1a2, Col3a1) were significantly decreased in TAC+Rio, when compared to TAC+Sol. IPA analysis revealed that the activation of biological pathways in response to TAC, like actin cytoskeleton- and Integrin signalling, renin-angiotensin or cardiac hypertrophy signalling was attenuated when Riociguat was administered. Conclusion Riociguat attenuates pressure overload induced LV remodelling resulting in less hypertrophy, improved heart function and less alteration of gene expression pattern.

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Impact of exercise training on ventricular properties in a canine model of congestive heart failure

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1997.272.3.h1382 ◽

1997 ◽

Vol 272 (3) ◽

pp. H1382-H1390 ◽

Cited By ~ 4

Author(s):

K. Todaka ◽

J. Wang ◽

G. H. Yi ◽

M. Knecht ◽

R. Stennett ◽

...

Keyword(s):

Heart Failure ◽

Exercise Training ◽

Heart Function ◽

Systolic Pressure ◽

Cardiac Pacing ◽

Left Ventricular ◽

Lv Function ◽

Myocardial Stiffness

Exercise training improves functional class in patients with chronic heart failure (CHF) via effects on the periphery with no previously documented effect on intrinsic left ventricular (LV) properties. However, because methods used to evaluate in vivo LV function are limited, it is possible that some effects of exercise training on the failing heart have thus far eluded detection. Twelve dogs were instrumented for cardiac pacing and hemodynamic recordings. Hearts were paced rapidly for 4 wk. Six of the dogs received daily treadmill exercise (CHF(EX), 4.4 km/h, 2 h/day) concurrent with rapid pacing, while the other dogs remained sedentary (CHFs). Hemodynamic measurements taken in vivo at the end of 4 wk revealed relative preservation of maximum rate of pressure rise (2,540 +/- 440 vs. 1,720 +/- 300 mmHg/s, P < 0.05) and LV end-diastolic pressure (9 +/- 5 vs. 19 +/- 4 mmHg, P < 0.05) in CHF(EX) compared with CHFs. The hearts were then isolated and cross perfused for in vitro measurement of isovolumic pressure-volume relations; these results were compared with those of six normal dogs (N). Systolic function was similarly depressed in both groups of pacing animals [end-systolic elastance (Ees) values of 1.66 +/- 0.47 in CHFs, 1.77 +/- 0.38 in CHF(EX), and 3.05 +/- 0.81 mmHg/ml in N, with no changes in volume axis interceptors of the end-systolic pressure-volume relationship]. The diastolic myocardial stiffness constant, k, was elevated in CHFs and was normalized by exercise training (32 +/- 3 in CHFs, 21 +/- 3 in CHF(EX), 20 +/- 4 in N). Thus daily exercise training preserved in vivo hemodynamics during 4 wk of rapid cardiac pacing and was accompanied by a significant change in diastolic myocardial stiffness in vitro. These findings suggest that changes in heart function may contribute to the overall beneficial hemodynamic effects of exercise training in CHF by a significant effect on diastolic properties.

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IL-18 induction of osteopontin mediates cardiac fibrosis and diastolic dysfunction in mice

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.01285.2008 ◽

2009 ◽

Vol 297 (1) ◽

pp. H76-H85 ◽

Cited By ~ 54

Author(s):

Qianli Yu ◽

Randy Vazquez ◽

Elham Vali Khojeini ◽

Chirag Patel ◽

Raj Venkataramani ◽

...

Keyword(s):

Diastolic Dysfunction ◽

Cardiac Fibrosis ◽

Interstitial Fibrosis ◽

Cardiac Fibroblasts ◽

Pressure Overload ◽

Volume Overload ◽

Left Ventricular Pressure ◽

Neutralizing Antibody ◽

Left Ventricular ◽

Fibrotic Process

Osteopontin (OPN), a key component of the extracellular matrix, is associated with the fibrotic process during tissue remodeling. OPN and the cytokine interleukin (IL)-18 have been shown to be overexpressed in an array of human cardiac pathologies. In the present study, we determined the role of IL-18 in the regulation of cardiac OPN expression and the subsequent interstitial fibrosis and diastolic dysfunction. We demonstrated parallel increases in IL-18, OPN expression, and interstitial fibrosis in murine models of left ventricular pressure and volume overload. Exogenous recombinant (r)IL-18 administered for 2 wk increased cardiac OPN expression, interstitial fibrosis, and diastolic dysfunction. Stimulation of the T helper (Th)1 lymphocyte phenotype with a selective toll-like receptor (TLR)9 agonist induced cardiac IL-18 and OPN expression, which was associated with increased cardiac fibrillar collagen concentrations and interstitial fibrosis resulting in diastolic dysfunction. rIL-18 induced OPN expression and protein levels in primary of cardiac fibroblast cultures. Conditioned media from TLR9-stimulated T lymphocyte cultures induced IL-18 and OPN expression in cardiac fibroblasts, while blockade of the IL-18 receptor with a neutralizing antibody abolished the increase in OPN expression. Furthermore, a mutation in the transcriptional factor interferon regulatory factor (IRF)1 or IRF1 small interfering RNA (siRNA) resulted in the decreased expression of IL-18 and OPN in cardiac fibroblasts. With pressure overload, IRF1-mutant mice showed downregulation of IL-18 and OPN expression in cardiac tissue, reduced cardiac fibrotic development, and increased left ventricular function compared with wild type. These results provide direct evidence that the induction of IL-18 regulates OPN-mediated cardiac fibrosis and diastolic dysfunction.

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Abstract 100: A MicroRNA Signature for Left Ventricular Reverse Remodeling in Chronic Systolic Heart Failure

Circulation Research ◽

10.1161/res.121.suppl_1.100 ◽

2017 ◽

Vol 121 (suppl_1) ◽

Author(s):

Olivia Ziegler ◽

Ravi Shah ◽

Kirsty Danielson ◽

Chun Yang Xiao ◽

Dustin Rabideau ◽

...

Keyword(s):

Heart Failure ◽

In Silico ◽

Systolic Heart Failure ◽

Left Ventricular ◽

Reverse Remodeling ◽

Murine Models ◽

Clinical Model ◽

Left Ventricular Reverse Remodeling

Introduction: Left ventricular reverse remodeling (LVRR) in heart failure (HF) is linked to improved patient outcomes. Current strategies to identify individuals who respond favorably to therapy in HF are limited. Though circulating microRNAs (miRs) show epigenetic regulation of LVRR in vivo , there is little clinical data linking plasma-circulating miRs to LVRR. Here we employ a point-of-care microRNA assay, Firefly, in silico analyses, and murine models of HF to characterize profiles of circulating miRs that prognosticate LVRR in patients with HF undergoing guideline directed therapy. Hypothesis: Profiles of miRs in circulating plasma will prognosticate LVRR in patients with HF better than the current clinical model alone and may play a functional role in LVRR. Methods: Plasma from 64 patients from the PROTECT study who had serial echocardiography and available plasma at pre-randomization study visit were run on Abcam’s Firefly platform to assay levels of 51 miRs, selected on prior sequencing efforts (for discovery) and published roles in CVD. miR levels were subject to PC analysis to predict LVRR. Candidate miRs were then validated in a murine model of transverse aortic constriction-induced heart failure (TAC-HF) and their function assessed in cardiomyocyte culture systems. Results: Principle component analysis revealed 4 PCs accounting for 62.4% of the observed variation without significant association with extant markers of HF. When PC2 miR levels were added to the clinical model prognostic ability for LVRR improved substantially (AIC 79.5, (OR=6.84, 95% CI 1.81-25.80, P= 0.005). In silico analysis was then applied to generate networks of mRNAs regulated by PC2 miRs. In the murine TAC-HF model, miRs 423, 212, 221, 193b were differentially regulated, as were the predicted targets of these miRs. These miRs, particularly in combination, appeared to be regulators of cardiac hypertrophy in vitro . Conclusions: Circulating miR profiles in HF improve prognosticative ability for patients who will undergo LVRR over the clinical model alone. Additionally these miRs and their targets are dynamically regulated in murine models of HF, suggesting they may have functional and potential therapeutic utility in addition to their prognostic power.

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Abstract 419: Stim1 is Associated With Calcium Microdomains That are Required for Myofilament Remodeling and Signaling During Cardiac Hypertrophy

Circulation Research ◽

10.1161/res.117.suppl_1.419 ◽

2015 ◽

Vol 117 (suppl_1) ◽

Author(s):

Cory Parks ◽

Ryan D Sullivan ◽

Salvatore Mancarella

Keyword(s):

Cardiac Hypertrophy ◽

Heart Function ◽

Cardiac Contractility ◽

Pressure Overload ◽

Left Ventricular ◽

Neonatal Rat ◽

Excitable Cells ◽

Rat Cardiomyocytes ◽

Cell Contractility

Stromal Interaction Protein 1 (STIM1) is the intracellular component of the store operated calcium channels. It is a ubiquitous Ca2+ sensor, prevalently located in the sarcoplasmic reticulum. In non-excitable cells, STIM1 is a key element in the generation of Ca2+signals that lead to gene expression and cell proliferation. A growing body of literature now suggests that STIM1 is important for normal heart function and plays a key role in the development of pathological cardiac hypertrophy. However, the precise mechanisms involving STIM1 and the Ca2+ signaling in excitable cells are not clearly established. We show that in neonatal rat cardiomyocytes, the spatial properties of STIM1-dependent Ca2+ signals determine restricted Ca2+ microdomains that regulate myofilaments remodeling and spatially segregated activation of pro-hypertrophic factors. Indeed, in vivo data obtained from an inducible cardiac restricted STIM1 knockout mouse, exhibited left ventricular dilatation associated with reduced cardiac contractility, which was corroborated by impaired single cell contractility. Furthermore, mice lacking STIM1 showed less adverse structural remodeling in response to pathological pressure overload-induced cardiac hypertrophy (transverse aortic constriction, TAC). We further show that the Ca2+ pool associated with STIM1 is the ON switch for extracellular signal-regulated kinase (ERK1/2)-mediated cytoplasm to nucleus signaling. These results highlight how STIM1-dependent Ca2+ microdomains have a major impact on intracellular Ca2+ homeostasis, cytoskeletal remodeling, signaling and cardiac function, even when excitation-contraction coupling is present.

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