Fibrosis In Heart Failure Research Articles

HDAC class I inhibitor, Mocetinostat, reverses cardiac fibrosis in heart failure and diminishes CD90+ cardiac myofibroblast activation.

BackgroundInterstitial fibrosis and fibrotic scar formation contribute to cardiac remodeling and loss of cardiac function in myocardial infarction (MI) and heart failure. Recent studies showed that histone deacetylase (HDAC) inhibitors retard fibrosis formation in acute MI settings. However, it is unknown whether HDAC inhibition can reverse cardiac fibrosis in ischemic heart failure. In addition, specific HDAC isoforms involved in cardiac fibrosis and myofibroblast activation are not well defined. Thus, the purpose of this study is to determine the effects of selective class I HDAC inhibition on cardiac fibroblasts activation and cardiac fibrosis in a congestive heart failure (CHF) model secondary to MI.MethodsMI was created by left anterior descending (LAD) coronary artery occlusion. Class I HDACs were selectively inhibited via Mocetinostat in CD90+ fibroblasts isolated from atrial and ventricular heart tissue in vitro. In vivo, Class I HDACs were inhibited in 3 weeks post MI rats by injecting Mocetinostat for the duration of 3 weeks. Cardiac function and heart tissue were analyzed at 6 weeks post MI.ResultsIn sham hearts, HDAC1 and HDAC2 displayed differential expression patterns where HDAC1 mainly expressed in cardiac fibroblast and HDAC2 in cardiomyocytes. On the other hand, we showed that HDAC1 and 2 were upregulated in CHF hearts, and were found to co-localize with CD90+ cardiac fibroblasts. In vivo treatment of CHF animals with Mocetinostat improved left ventricle end diastolic pressure and dp/dt max and decreased the total collagen amount. In vitro treatment of CD90+ cells with Mocetinostat reversed myofibroblast phenotype as indicated by a decrease in α-Smooth muscle actin (α-SMA), Collagen III, and Matrix metalloproteinase-2 (MMP2). Furthermore, Mocetinostat increased E-cadherin, induced β-catenin localization to the membrane, and reduced Akt/GSK3β signaling in atrial cardiac fibroblasts. In addition, Mocetinostat treatment of atrial CD90+ cells upregulated cleaved-Caspase3 and activated the p53/p21 axis.ConclusionsTaken together, our results demonstrate upregulation of HDAC1 and 2 in CHF. In addition, HDAC inhibition reverses interstitial fibrosis in CHF. Possible anti-fibrotic actions of HDAC inhibition include reversal of myofibroblast activation and induction of cell cycle arrest/apoptosis.

The Boston AF Symposium 2014 Abstracts

Mineralocorticoid receptor(MR) antagonism reduces sudden cardiac death in heart failure, but the underlying mechanism remains poorly understood. Concurrent treatment with an MR antagonist during rapid ventricular pacing (RVP) prevents development of adverse ventricular electrophysiological remodeling, interstitial fibrosis, inflammatory cytokine gene activation, and ventricular tachyarrhythmia inducibility without diminishing the extent of systolic dysfunction. We hypothesized that attenuating preexistent inflammatory pathways and myocardial fibrosis with eplerenone after systolic heart failure is established by rapid pacing can reduce electrical activation delays and arrhythmia vulnerability. Dogs subjected to RVP for 8 weeks in the absence or presence of eplerenone treatment during the final 4 weeks of pacing were assessed by echocardiography, electrophysiology study,ventricular fibrosis measurements, and inflammatory cytokine mRNA expression analysis. Eplerenone reversed preexistent ventricular activation delays, interstitial fibrosis, inflammatory cytokine (interleukin-6, tumor necrosis factor-α) gene overexpression, and arrhythmia vulnerability in ventricular paced dogs with heart failure. Eplerenone failed to improve left ventricular systolic dysfunction or chamber enlargement. A correlation between severity of fibrosis and ventricular arrhythmia inducibility was found. MR antagonism regresses rapid pacing-induced electrical delays, inflammatory cytokine gene activation, and fibrosis in heart failure. Ventricular arrhythmia vulnerability in heart failure is correlated with extent of fibrosis and electrical activation delays during premature excitation.

Eplerenone‐Mediated Regression of Electrical Activation Delays and Myocardial Fibrosis in Heart Failure

Eplerenone Reverses Electrical Delays and FibrosisIntroductionMineralocorticoid receptor (MR) antagonism reduces sudden cardiac death in heart failure, but the underlying mechanism remains poorly understood. Concurrent treatment with an MR antagonist during rapid ventricular pacing (RVP) prevents development of adverse ventricular electrophysiological remodeling, interstitial fibrosis, inflammatory cytokine gene activation, and ventricular tachyarrhythmia inducibility without diminishing the extent of systolic dysfunction. We hypothesized that attenuating preexistent inflammatory pathways and myocardial fibrosis with eplerenone after systolic heart failure is established by rapid pacing can reduce electrical activation delays and arrhythmia vulnerability.Methods and ResultsDogs subjected to RVP for 8 weeks in the absence or presence of eplerenone treatment during the final 4 weeks of pacing were assessed by echocardiography, electrophysiology study, ventricular fibrosis measurements, and inflammatory cytokine mRNA expression analysis. Eplerenone reversed preexistent ventricular activation delays, interstitial fibrosis, inflammatory cytokine (interleukin‐6, tumor necrosis factor‐α) gene overexpression, and arrhythmia vulnerability in ventricular paced dogs with heart failure. Eplerenone failed to improve left ventricular systolic dysfunction or chamber enlargement. A correlation between severity of fibrosis and ventricular arrhythmia inducibility was found.ConclusionsMR antagonism regresses rapid pacing‐induced electrical delays, inflammatory cytokine gene activation, and fibrosis in heart failure. Ventricular arrhythmia vulnerability in heart failure is correlated with extent of fibrosis and electrical activation delays during premature excitation.

Galectin 3 and incident atrial fibrillation in the community

Galectin 3 (Gal-3) is a potential mediator of cardiac fibrosis, and Gal-3 concentrations predict incident heart failure. The same mechanisms that lead to cardiac fibrosis in heart failure may influence development of atrial fibrosis and atrial fibrillation (AF). We examined the association of Gal-3 and incident AF in the community. Plasma Gal-3 concentrations were measured in 3,306 participants of the Framingham Offspring cohort who attended the sixth examination cycle (1995-1998, mean age 58 years, 54% women). Cox proportional hazards regression models were used to assess the association of baseline Gal-3 concentrations and incident AF. Over a median follow-up period of 10 years, 250 participants developed incident AF. Crude incidence rates of AF by increasing sex-specific Gal-3 quartiles were 3.7%, 5.9%, 9.1%, and 11.5% (log-rank test P < .0001). In age- and sex-adjusted analyses, each 1-SD increase in loge-Gal-3 was associated with a 19% increased hazard of incident AF (hazard ratio 1.19, 95% CI 1.05-1.36, P = .009). This association was not significant after adjustment for traditional clinical AF risk factors (hazard ratio 1.12, 95% CI 0.98-1.28, P = .10). Higher circulating Gal-3 concentrations were associated with increased risk of developing AF over the subsequent 10 years in age- and sex-adjusted analyses but not after accounting for other traditional clinical AF risk factors. Our results do not support a role for Gal-3 in AF risk prediction. Further studies are needed to evaluate whether Gal-3 plays a role in the development of AF substrate similar to HF.

Relationship Between Galectin-3 Levels and Mineralocorticoid Receptor Antagonist Use in Heart Failure: Analysis From HF-ACTION

BackgroundGalectin-3 (Gal-3) is a marker of myocardial fibrosis, and elevated levels are associated with adverse outcomes. Mineralocorticoid receptor antagonists (MRAs) modulate cardiac fibrosis in heart failure (HF) patients and have been shown to improve long-term outcomes. We examined whether treatment effects from MRA use differed by Gal-3 levels in ambulatory heart failure patients enrolled in HF-ACTION. Methods and ResultsHF-ACTION was a randomized controlled trial of exercise training versus usual care in patients with HF due to LV systolic dysfunction (New York Heart Association functional class II–IV, left ventricular ejection fraction ≤0.35, median follow-up 2.5 years). Galectin-3 was assessed at baseline in 895 patients. The end point was all-cause mortality or all-cause hospitalization (ACM+ACH); all-cause mortality (ACM) was a key secondary end point. A differential association of MRA use by increasing Gal-3 concentration was tested with the use of interaction terms in Cox proportional hazards models, adjusted for covariates previously identified in this cohort as well as age, sex, and race. Inverse propensity-weighted (IPW) methods were also used to assess this association. Approximately one-half (n = 401) of the patients were on an MRA. There was no significant interaction for the associations of Gal-3 levels and MRA use for either end point (adjusted interaction P = .76 for ACM+ACH; P = .26 for ACM). There was no evidence of improved outcomes for patients on an MRA compared with those not on MRA for either end point (hazard ratio [HR] 1.02, 95% confidence interval [CI] 0.85–1.23, P = .8; and HR = 1.15, 95% CI [0.82–1.61], P = .4; respectively). IPW analysis was consistent with the results of the adjusted analysis. ConclusionOur study showed no evidence of interaction between Gal-3 and treatment effect of MRA. Whether biomarkers may be used to predict which patients may benefit from an mineralocorticoid receptor antagonist in HF requires further investigation.

Abstract 304: Estrogen Plays a Protective Role in Advanced Heart Failure by Suppressing Cardiac Fibrosis Associated Genes via miR129 Induction

We have previously shown that short term treatment of estrogen(E2) can rescue advance heart failure(HF) and decreases associated fibrosis. We hypothesized that E2 can reduce fibrosis by regulating the levels of specific microRNAs including miR129-5p(miR129) through ERβ mediated mechanism. We used transaortic constriction to induce HF in male mice, and once the ejection fraction (EF) reached ~30%, one group of animals was sacrificed (HF), and the other group received 17b-estradiol via a subcutaneous pellet implant (0.012mg/pellet, n=16) (E2) for 10 days. Sham-operated mice served as CTRL. Serial echocardiography was performed to monitor cardiac structure and function. Short-term E2 treatment rescued pressure overload-induced decompensated HF in mice by restoring the EF from 33.17±1.12% to 53.05±1.29 (p &lt;0.001, n=16). E2 decreased both interstitial and perivascular fibrosis in HF. Microarray analysis comparing HF with E2 revealed ~70 microRNAs including miR129 regulated by E2. qPCR validation revealed that E2 treatment upregulates miR129 by 2 folds compared to HF restoring it to CTRL levels. Treatment of HF with ERβ agonist (DPN), but not ERα agonist (PPT) resulted in the upregulation of miR129 indicating the E2 mediated induction of miR129 is mediated through ERβ. In vitro, angiotensin II treatment significantly downregulated miR129 expression in neonatal rat fibroblasts (NRVF) which was restored by E2 and DPN but not by E2+ERβ antagonist (PHPT) further confirming the role of ERβ in regulating miR129. In vitro, OE of miR129 in both neonatal and adult rat cardiac fibroblasts (ARVF) resulted in significant downregulation of transcripts of many in-silico predicted pro-fibrotic target genes including EGFR, RUNX, GREM1, COL2A, PDGFA, PDGFRA and the transcription factor SOX4. OE of miR129 in fibroblasts also resulted in downregulation of EGFR protein. Gain of miR129 prevented the transition of fibroblasts to myofibroblasts in both NRVF and ARVF and inhibited fibroblast proliferation in vitro. In conclusion, E2 treatment during HF induces miR129 likely through ERβ. MiR129 represses fibrosis by targeting key genes associated with cardiac fibrosis, inhibits fibroblast proliferation and fibroblast to myofibroblast transition.

Osteopontin-mediated myocardial fibrosis in heart failure: a role for lysyl oxidase?

We investigated whether the pro-fibrotic matricellular protein osteopontin (OPN) is associated with the enzymes involved in the extracellular synthesis of fibril-forming collagen type I (i.e. procollagen C-proteinase, PCP) and its cross-linking to form insoluble fibrils (i.e. lysyl oxidase, LOX) in heart failure (HF) of hypertensive origin. OPN, PCP, and LOX were assessed by histochemical and molecular methods in the myocardium of 21 patients with hypertensive heart disease (HHD) and HF. Whereas the myocardial expression of OPN was very scarce in control hearts (n = 10), it was highly expressed in HF patients (P < 0.0001). OPN was directly correlated with LOX (r = 0.460, P = 0.041), insoluble collagen (r = 0.534, P = 0.015), pulmonary capillary wedge pressure (r = 0.558; P = 0.009), and left-ventricular (LV) chamber stiffness (r = 0.458, P = 0.037), and inversely correlated with LV ejection fraction (r = -0.513, P = 0.017) in all patients. OPN did not correlate with PCP and other parameters assessing collagen synthesis by fibroblasts or degradation by matrix metalloproteinases. In vitro studies showed that OPN significantly (P < 0.05) increases the expression and activity of LOX in human cardiac and dermal fibroblasts. An excess of OPN is associated with increased LOX and insoluble collagen, as well as with LV stiffness and systolic dysfunction in patients with HHD and HF. In addition, OPN up-regulates LOX in human fibroblasts. It is suggested that the OPN-LOX axis might facilitate the formation of insoluble collagen (i.e. stiff and resistant to degradation) and the subsequent alteration in LV mechanical properties and function in patients with HHD and HF.

Bio-imaging: late gadolinium enhancement in dilated cardiomyopathy and its relation to novel biomarkers of fibrosis and remodeling

Background Focal myocardial fibrosis is frequently observed in dilated cardiomyopathy (DCM) and predicts future major adverse cardiovascular events and patient outcome. However, the pathogenesis of fibrosis in DCM remains poorly understood. Novel serum biomarkers of fibrosis such as Endoglin have been recently identified as a trigger of myocardial fibrosis in heart failure. Accordingly, we sought to investigate the relationship between myocardial tissue fibrosis as identified by noninvasive late gadolinium contrast enhancement (LGE) CMR and serum biomarkers of fibrosis/ remodeling in a cohort of DCM patients.

Abstract 18603: Estrogen Plays a Protective Role in Advanced Heart Failure by Regulating Target Genes of miR-129-5p Suppressing Cardiac Fibrosis

Background: Moderate cardiac fibrosis has been reported in advanced heart failure (HF) induced by pressure overload in mice. We have previously shown that short term estrogen(E2) therapy starting after the advanced HF can rescue HF. E2 has been shown to reverse fibrosis through estrogen receptor beta(ERb). Here, we explored whether E2 can suppress cardiac fibrosis by inducing miR-129-5p expression through ERb mediated mechanism and verified its key target genes. Methods and results: We used transaortic constriction to induce HF in male mice, and once the ejection fraction (EF) reached ∼30%, one group of animals was sacrificed (HF group), and the other group received 17b-estradiol via a subcutaneous pellet implant (0.012mg/pellet, n=16) (E2 group) for 10 days. Sham-operated mice served as CTRL. Serial echocardiography was performed to monitor cardiac structure and function. Short-term E2 treatment rescued pressure overload-induced decompensated HF in mice by restoring the EF from 33.17±1.12% to 53.05±1.29(p &lt;0.001). E2 also decreased both interstitial and prevascular fibrosis in HF. MicroRNA microarray analysis and qPCR validation revealed that miR-129-5p is upregulated ∼2 fold in E2 group compared to HF group. Interestingly, miR-129-5p showed no significant change in E2 versus CTRL suggesting altered miR-129-5p expression in HF was restored to CTRL group by E2 treatment. Treatment of HF with ERb agonist (DPN), but not ER-alpha agonist (PPT), also resulted in the upregulation of miR-129-5p indicating the estrogen mediated induction of miR-129-5p is possibly mediated through ERb. In vitro, angiotensin II treatment significantly downregulated miR-129-5p expression in fibroblasts which was restored by estrogen and DPN but not by ERb antagonist (PHPT) further confirming the role of ERb in regulating miR-129-5p. In vitro, over-expression of miR129-5p in fibroblasts resulted in the significant down-regulation of many potential pro-fibrotic target genes including COL1A, PDGFA, GREM1 and the transcription factor SOX4. Conclusion: Our data strongly suggests that estrogen treatment during HF induces miR-129-5p likely through ERb. Mechanistically, miR-129-5p represses fibrosis by targeting key component genes associated with cardiac fibrosis.

Liver Hemangioma Might Lead to overestimation of Liver Fibrosis by Fibroscan; A Missed Issue in Two Cases

The assessment of liver fibrosis is an important way for prediction of liver disease progression and patient's prognosis. Liver stiffness measurement (LSM) is strongly associated with stage of liver diseases. overestimation of liver fibrosis in heart failure has been reported. We would like to introduce a new leading cause of liver fibrosis overestimation by presentation of two cases. one case with right lobe hemangioma has an overestimation of liver fibrosis. The result completely changed when Fibroscan was performed in patient's left lobe. Interestingly, another case with left lobe hemangioma had overestimation of fibrosis in her left lobe but, right lob Fibroscan was normal. We found that liver hemangioma may leads to overestimation of liver stiffness and the correct inspection of liver echogenicity before any interpretation of high liver stiffness is recommended. We suggest that patient with higher level of Fibroscan score repeat it in other sides of the liver. Also, they should be evaluated by sonography for ruling out of possible confounders such as hepatic hemangioma.

Reduced Endoglin Activity Limits Cardiac Fibrosis and Improves Survival in Heart Failure

Heart failure is a major cause of morbidity and mortality worldwide. The ubiquitously expressed cytokine transforming growth factor-β1 (TGFβ1) promotes cardiac fibrosis, an important component of progressive heart failure. Membrane-associated endoglin is a coreceptor for TGFβ1 signaling and has been studied in vascular remodeling and preeclampsia. We hypothesized that reduced endoglin expression may limit cardiac fibrosis in heart failure. We first report that endoglin expression is increased in the left ventricle of human subjects with heart failure and determined that endoglin is required for TGFβ1 signaling in human cardiac fibroblasts using neutralizing antibodies and an siRNA approach. We further identified that reduced endoglin expression attenuates cardiac fibrosis, preserves left ventricular function, and improves survival in a mouse model of pressure-overload-induced heart failure. Prior studies have shown that the extracellular domain of endoglin can be cleaved and released into the circulation as soluble endoglin, which disrupts TGFβ1 signaling in endothelium. We now demonstrate that soluble endoglin limits TGFβ1 signaling and type I collagen synthesis in cardiac fibroblasts and further show that soluble endoglin treatment attenuates cardiac fibrosis in an in vivo model of heart failure. Our results identify endoglin as a critical component of TGFβ1 signaling in the cardiac fibroblast and show that targeting endoglin attenuates cardiac fibrosis, thereby providing a potentially novel therapeutic approach for individuals with heart failure.

Abstract 1: Opposing Roles for Endoglin and Soluble Endoglin in Cardiac Remodeling and Heart Failure

Transforming growth factor beta-1 (TGFb1) promotes cardiac fibrosis. The transmembrane co-receptor Endoglin (Eng; CD105) facilitates TGFb1 signaling via SMAD effector proteins. In contrast, a circulating form of soluble endoglin (sEng) inhibits TGFb1 signaling in vascular endothelium. We recently reported that increased sEng levels in human serum correlate with clinical indices of heart failure severity. Therefore, we tested the hypothesis that Eng and sEng mediate opposing effects on cardiac fibrosis in heart failure. In male, wild-type mice (WT), Eng expression increased in the left ventricle (LV) after 2, 4, and 10 weeks of thoracic aortic constriction (TAC) accompanied by progressive LV fibrosis and hypertrophy. In contrast to WT mice, Eng haploinsufficient (Eng +/− ) mice had preserved LV function (FS%: 78±4 vs 22±16, Eng +/− vs WT, p&lt;0.01) and improved survival [88%(7/8) vs 50%(4/8), Eng +/− vs WT, p&lt;0.001) after 10 weeks of TAC. Reduced LV fibrosis was observed in Eng +/− mice, while LV mass, cardiomyocyte hypertrophy, and calcineurin, SerCA, and bMHC expression were comparable to WT after TAC. Capillary density was significantly higher in Eng +/− mice after TAC compared to WT. LV SMAD phosphorylation (pSMAD) after TAC was studied and a preferential increase was observed in pSMAD1/5/8 expression in Eng +/− mice as compared to WT mice, in which cardiac pSmad2/3 expression was increased. The dependence of TGFb1 induced collagen synthesis on Eng expression was tested in vitro using human cardiac fibroblasts (hCF). Neutralizing antibodies and siRNA against Eng each attenuated TGFb1 induced collagen synthesis. In contrast, conditioned media from cells transfected with an adenovirus over-expressing sEng attenuated pSMAD2/3 expression and TGFb1 induced collagen synthesis in hCF. Treatment of hCF with recombinant sEng blocked TGFb1 induced collagen synthesis in a dose-dependent manner, confirming an inhibitory role of sEng. These results indicate that Eng and sEng mediate opposite effects on TGFb1 induced collagen synthesis. Reduced Eng expression uncouples cardiac fibrosis from cardiomyocyte hypertrophy, promotes SMAD1/5/8-signaling, and enhances angiogenesis. Eng may represent a novel therapeutic target to improve survival in heart failure.

Myocardial fibrosis detected by cardiac magnetic resonance imaging in heart failure: Impact on remodeling, diastolic function and BNP levels

Myocardial fibrosis, progressive over-accumulation of extracellular matrix (ECM) components in cardiac muscle, defined as a key component of heart failure and since then various studies showed a strong connection between fibrosis and progression of heart failure. The impaired left ventricular diastolic and systolic functions that are originated by fibrosis are used to predict poor clinical outcome in dilated cardiomyopathy. Even though endomyocardial biopsy is still considered as a gold standard, various noninvasive imaging techniques have been used to detect presence, location and extend of myocardial fibrosis. Cardiac magnetic resonance emerged as a crucial noninvasive imagining technique because of its high accuracy and high fidelity in detection of fibrosis. The noninvasive assessment of fibrosis is advantageous in early prediction of possible adverse outcomes and creates an opportunity to utilize new therapeutic approaches that target fibrosis in heart failure.

Diminished Cardiac Fibrosis in Heart Failure is Associated with Altered Ventricular Arrhythmia Phenotype

We sought to define the role of interstitial fibrosis in the proarrhythmic phenotype of failing ventricular myocardium. Multiple cellular events that occur during pathological remodeling of the failing ventricle are implicated in the genesis of ventricular tachycardia (VT), including interstitial fibrosis. Recent studies suggest that ventricular fibrosis is reversible, and current anti-remodeling therapies attenuate ventricular fibrosis. However, the role of interstitial fibrosis in the proarrhythmic phenotype of failing ventricular myocardium is currently not well defined. Class II histone deacetylases (HDACs) have been implicated in promoting collagen biosynthesis. As these enzymes are inhibited by protein kinase D1 (PKD1), we studied mice with cardiomyocyte-specific transgenic over-expression of a constitutively active mutant of PKD1 (caPKD). caPKD mice were compared with animals in which cardiomyopathy was induced by severe thoracic aortic banding (sTAB). Hearts were analyzed by echocardiographic and electrocardiographic means. Interstitial fibrosis was assessed by histology and quantified biochemically. Ventricular arrhythmias were induced by closed-chest, intracardiac pacing. Similar degrees of hypertrophic growth, systolic dysfunction and mortality were observed in the two models. In sTAB mice, robust ventricular fibrosis was readily detected, but myocardial collagen content was significantly reduced in caPKD mice. As expected, VT was readily inducible by programmed stimulation in sTAB mice and VT was less inducible in caPKD mice. Surprisingly, episodes of VT manifested longer cycle lengths and longer duration in caPKD mice. Attenuated ventricular fibrosis is associated with reduced VT inducibility, increased VT duration, and significantly longer arrhythmia cycle length.

Bone Marrow-Derived Cells Contribute to Fibrosis in the Chronically Failing Heart

Cardiac fibrosis contributes significantly to the phenotype of the chronically failing heart. It is not clear whether in this setting the fibrosis is contributed by native cardiac fibroblasts or alternatively by recruitment of cells arising from the bone marrow. We aimed to determine the contribution of bone marrow-derived cells to cardiac fibrosis in the failing heart and to investigate potentially contributing cytokines. Bone marrow-derived fibrocyte recruitment to the failing heart was studied in a transgenic (Mst1 mice) model of dilated cardiomyopathy. In conjunction, we examined the role of stromal-derived factor-1 (SDF-1), a key chemoattractant, by assessing myocardial expression and secretion by cardiomyocytes and in clinical samples. Bone marrow-derived cells were recruited in significantly greater numbers in Mst1 versus control mice (P < 0.001), contributing 17 +/- 4% of the total fibroblast load in heart failure. Patients with heart failure had higher plasma levels of SDF-1 than healthy control subjects (P < 0.01). We found that cardiomyocytes constitutively secrete SDF-1, which is significantly up-regulated by angiotensin II. SDF-1 was shown to increases cardiac fibroblast migration by 59% (P < 0.05). Taken together, our data suggest that recruitment of bone marrow-derived cells under the influence of factors, including SDF-1, may play an important role in the pathogenesis of cardiac fibrosis in heart failure.

IL-17 induces myocardial fibrosis and enhances RANKL/OPG and MMP/TIMP signaling in isoproterenol-induced heart failure

Objective This study was designed to investigate whether IL-17 can regulate the expression of the MMP/TIMP system, the OPG/RANK/RANKL system, or type-I and type-III collagen fibers in a rat model of isoproterenol-induced heart failure (HF). We also investigated the effect of IL-17 on myocardial fibrosis in this model. Methods HF was induced in Wistar–Kyoto rats by hypodermic injection of isoproterenol (ISO) twice every 24 h. After 2 months, the surviving rats were divided into three groups: monoclonal Anti-IL-17 Ab (100 μg/day), IgG (100 μg/day) or PBS were injected five times every 48 h (i.p.). One day after the last injection, all of the rats were sacrificed. H&E and Masson staining were used to evaluate myocardial fibrosis, and immunohistochemistry was used to measure the levels of MMP-1, TIMP-1, TIMP-4, OPG, RANKL, type-I and type-III collagen fibers. We also treated adult rat cardiac fibroblasts with IL-17 (10 ng/ml), IL-17 (10 ng/ml) + OPG (10 ng/ml), IL-17 (10 ng/ml) + anti-RANKL Ab (100 ng/ml), or PBS for 24 h, realtime RT-PCR was used to measure the expressions of MMP-1. Results The expressions of MMP-1, RANKL, and type-I and -III collagen fibers decreased, and the expressions of TIMP-1, TIMP-4, and OPG increased in the Anti-IL-17 group compared to controls. H&E and Masson staining revealed that blockade of IL-17 can improve myocardial fibrosis in HF. IL-17 increased the expression of MMP-1 in cardiac fibroblasts, and OPG and anti-IL-17 Ab could inhibit this function partly. Thus, IL-17 was dependent on the RANKL/OPG system to induce MMP-1 partly. Conclusion Our study demonstrates the contribution of IL-17 to myocardial fibrosis in isoproterenol-induced HF. IL-17 can regulate the RANKL/OPG and MMP/TIMP systems in this model. The RANKL/OPG system is one of intermediaries between IL-17 and MMP-1 in cardiac fibroblasts. As a harmful cytokine, anti-IL-17 treatment is a potential therapeutic strategy in HF.

Evaluation of Diffuse Myocardial Fibrosis in Heart Failure with Cardiac Magnetic Resonance Contrast-enhanced T 1 Mapping

Objectives The purpose of this study was to investigate a noninvasive method for quantifying diffuse myocardial fibrosis with cardiac magnetic resonance imaging (CMRI). Background Diffuse myocardial fibrosis is a fundamental process in pathologic remodeling in cardiomyopathy and is postulated to cause increased cardiac stiffness and poor clinical outcomes. Although regional fibrosis is easily imaged with cardiac magnetic resonance, there is currently no noninvasive method for quantifying diffuse myocardial fibrosis. Methods We performed CMRI on 45 subjects (25 patients with heart failure, 20 control patients), on a clinical 1.5-T CMRI scanner. A prototype T1 mapping sequence was used to calculate the post-contrast myocardial T1 time as an index of diffuse fibrosis; regional fibrosis was identified by delayed contrast enhancement. Regional and global systolic function was assessed by cine CMRI in standard short- and long-axis planes, with echocardiography used to evaluate diastology. An additional 9 subjects underwent CMRI and endomyocardial biopsy for histologic correlation. Results Post-contrast myocardial T1 times correlated histologically with fibrosis (R = −0.7, p = 0.03) and were shorter in heart failure subjects than controls (383 ± 17 ms vs. 564 ± 23 ms, p Conclusions Contrast-enhanced CMRI T1 mapping identifies changes in myocardial T1 times in heart failure, which appear to reflect diffuse fibrosis.

148: Decorin regulates TGF-b stimulated fibrosis in heart failure and during LVAD support

148: Decorin regulates TGF-b stimulated fibrosis in heart failure and during LVAD support

Quantitative Changes in Mast Cell Populations After Left Ventricular Assist Device Implantation

Mast cells have been implicated as important in tissue remodeling and fibrosis. We investigated the effect of mechanical ventricular unloading upon myocardial fibrosis and cardiac mast cell density in patients undergoing left ventricular assist device (LVAD) implantation. Paired myocardial tissue samples were obtained from 30 patients with end-stage cardiomyopathy at the time of LVAD implantation and at the time of removal and were compared with samples taken from donor hearts. Tissue sections were stained and quantitated for mast cells and myocardial fibrosis. Mast cell density (tryptase positive cells) in cardiomyopathy was higher than that in donor hearts (33.5 +/- 3.6 SEM cells/10 fields vs.15.2 +/- 2.0 SEM cells/10 fields respectively, p = 0.04) and was lower than LVAD supported hearts (33.5 +/- 3.6 SEM cells/10 fields vs. 49.8 +/- 5.7 SEM cells/10 fields respectively, p = 0.01). Mast cells are primarily localized in areas of increased interstitial fibrosis adjacent to myocardial cells and not vessels. There was statistically significant correlation between mast cells and interstitial collagen (p = 0.03) in patients before LVAD implantation that did not persist after mechanical support (p = 0.18). These results suggest that mechanical support with left ventricular assist devices induces an increase in mast cell number in the myocardium and an associated decrease in myocardial fibrosis. We believe these data demonstrate a dual role for cardiac mast cells in the increase in fibrosis in heart failure and the decrease after LVAD and its associated cardiac improvement.

Early administration of either spironolactone or eprosartan reduces cardiac hypertrophy and fibrosis in rats with heart failure: possible involvement of ace and ace-2

P-140 Key Words: Aldosterone, Angiotensin II, Cardiac Hypertrophy