scholarly journals Effects of the absence of procollagen C-endopeptidase enhancer-2 on myocardial collagen accumulation in chronic pressure overload

2012 ◽  
Vol 303 (2) ◽  
pp. H234-H240 ◽  
Author(s):  
Catalin F. Baicu ◽  
Yuhua Zhang ◽  
An O. Van Laer ◽  
Ludivine Renaud ◽  
Michael R. Zile ◽  
...  
Keyword(s):  
Cardiac Fibroblasts ◽  
Pressure Overload ◽  
Left Ventricular ◽  
Bone Morphogenic Protein ◽  
Collagen Content ◽  
Fibrillar Collagen ◽  
Collagen Deposition ◽  
Myocardial Stiffness ◽  
Collagen Accumulation

Cardiac interstitial fibrillar collagen accumulation, such as that associated with chronic pressure overload (PO), has been shown to impair left ventricular diastolic function. Therefore, insight into cellular mechanisms that mediate excessive collagen deposition in the myocardium is pivotal to this important area of research. Collagen is secreted as a soluble procollagen molecule with NH2- and COOH (C)-terminal propeptides. Cleavage of these propeptides is required for collagen incorporation to insoluble collagen fibrils. The C-procollagen proteinase, bone morphogenic protein 1, cleaves the C-propeptide of procollagen. Procollagen C-endopeptidase enhancer (PCOLCE) 2, an enhancer of bone morphogenic protein-1 activity in vitro, is expressed at high levels in the myocardium. However, whether the absence of PCOLCE2 affects collagen content at baseline or after PO induced by transverse aortic constriction (TAC) has never been examined. Accordingly, in vivo procollagen processing and deposition were examined in wild-type (WT) and PCOLCE2-null mice. No significant differences in collagen content or myocardial stiffness were detected in non-TAC (control) PCOLCE2-null versus WT mice. After TAC-induced PO, PCOLCE2-null hearts demonstrated a lesser collagen content (PCOLCE2-null TAC collagen volume fraction, 0.41% ± 0.07 vs. WT TAC, 1.2% ± 0.3) and lower muscle stiffness compared with WT PO hearts [PCOLCE2-null myocardial stiffness (β), 0.041 ± 0.002 vs. WT myocardial stiffness, 0.065 ± 0.001]. In addition, in vitro, PCOLCE2-null cardiac fibroblasts exhibited reductions in efficiency of C-propeptide cleavage, as demonstrated by increases in procollagen α1(I) and decreased levels of processed collagen α1(I) versus WT cardiac fibroblasts. Hence, PCOLCE2 is required for efficient procollagen processing and deposition of fibrillar collagen in the PO myocardium. These results support a critical role for procollagen processing in the regulation of collagen deposition in the heart.

scholarly journals Increased macrophage-derived SPARC precedes collagen deposition in myocardial fibrosis

2018 ◽  
Vol 315 (1) ◽  
pp. H92-H100 ◽  
Author(s):  
Lindsay T. McDonald ◽  
Michael R. Zile ◽  
Yuhua Zhang ◽  
An O. Van Laer ◽  
Catalin F. Baicu ◽  
...  
Keyword(s):  
Myocardial Fibrosis ◽  
Time Course ◽  
Pressure Overload ◽  
Collagen Type I ◽  
Left Ventricular ◽  
Type I ◽  
Fibrillar Collagen ◽  
Collagen Deposition ◽  
Myocardial Stiffness ◽  
Insoluble Collagen

Myocardial fibrosis and the resultant increases in left ventricular stiffness represent pivotal consequences of chronic pressure overload (PO) that impact both functional capacity and the rates of morbid and mortal events. However, the time course and cellular mechanisms that underlie PO-induced fibrosis have not been completely defined. Secreted protein acidic and rich in cysteine (SPARC) is a matricellular protein that has been shown to be required for insoluble collagen deposition and increased myocardial stiffness in response to PO in mice. As macrophages are associated with increases in fibrillar collagen, the hypothesis that macrophages represent a source of increased SPARC production in the PO myocardium was tested. The time course of changes in the myocardial macrophage population was compared with changes in procollagen type I mRNA, production of SPARC, fibrillar collagen accumulation, and diastolic stiffness. In PO hearts, mRNA encoding collagen type I was increased at 3 days, whereas increases in levels of total collagen protein did not occur until 1 wk and were followed by increases in insoluble collagen at 2 wk. Increases in muscle stiffness were not detected before increases in insoluble collagen content (>1 wk). Significant increases in myocardial macrophages that coincided with increased SPARC were found but did not coincide with increases in mRNA encoding collagen type I. Furthermore, immunohistochemistry and flow cytometry identified macrophages as a cellular source of SPARC. We conclude that myocardial macrophages play an important role in the time-dependent increases in SPARC that enhance postsynthetic collagen processing, insoluble collagen content, and myocardial stiffness and contribute to the development of fibrosis. NEW & NOTEWORTHY Myocardial fibrosis and the resultant increases in left ventricular and myocardial stiffness represent pivotal consequences of chronic pressure overload. In this study a murine model of cardiac fibrosis induced by pressure overload was used to establish a time course of collagen expression, collagen deposition, and cardiac macrophage expansion.

scholarly journals Cardiac fibroblasts acquire properties of matrifibrocytes in vitro and in mice with pressure overload-induced congestive heart failure

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
K.M Herum ◽  
G Gilles ◽  
A Romaine ◽  
A.O Melleby ◽  
G Christensen ◽  
...  
Keyword(s):  
Heart Failure ◽  
Congestive Heart Failure ◽  
Cardiac Fibroblasts ◽  
Pressure Overload ◽  
Left Ventricular Pressure ◽  
Left Ventricular ◽  
Funding Source ◽  
High Stiffness

Abstract Introduction Activation of cardiac fibroblasts (CFB) is a key step in development of fibrosis in the heart. It was recently shown that, in addition to the well-studied myofibroblast (myoFB) phenotype, activated cardiac fibroblasts can adopt a newly defined matrifibrocyte phenotype, characterized by expression of extracellular matrix (ECM) genes associated with bone, cartilage and tendon development. However, it is unknown whether matrifibrocytes exists in the pressure-overloaded fibrotic and failing heart, and whether substrate stiffness drives differentiation. Hypothesis Matrifibrocyte differentiation occurs in vitro during culturing of primary cardiac fibroblasts, and in vivo in response to left ventricular pressure overload. Methods Left ventricular pressure overload induced by o-ring aortic banding (ORAB) induced cardiac phenotypes of concentric hypertrophic remodelling and congestive heart failure. Primary CFB from adult mice were cultured on plastic or soft polyacrylamide hydrogels (4.5 kPa) for various times. mRNA expression of phenotypic markers were measured by RT-PCR. Presence of smooth muscle α-actin (SMA) fibers was determined by immunocytochemistry. Results ECM genes normally expressed in bone and cartilage (COMP, CILP-2, OPG and SCX) were upregulated in hypertrophic left ventricles of mice with congestive heart failure. The myoFB marker acta2 was increased 2 weeks after ORAB, returned to baseline at 4 weeks and increased again at 20 weeks when the left ventricle was dilating and failing, indicating that the myoFB phenotype is not permanent. In vitro, primary CFB upregulated bone/cartilage-associated ECM genes after 12 days of culturing on plastic. Acta2 mRNA and SMA protein levels peaked after 9 days in culture whereafter they declined, indicating a shift in phenotype. Culturing primary CFB on soft (4.5 kPa) hydrogels delayed, but did not prevent, myoFB differentiation while expression of bone/cartilage ECM genes was absent or low, indicating that high stiffness is a driver of the matrifibrocyte phenotype. Blockers of mechanotransduction, SB431542 (TGFβRI inhibitor), Y27623 (ROCK inhibitor) and cyclosporine A (calcineurin inhibitor), completely inhibited myoFB differentiation but upregulated several matrifibrocyte markers, indicating that distinct signaling pathways regulate myoFB and matrifibrocyte differentiation. Removing inhibitors re-induced myofibroblast markers in cells on plastic but not on soft gels consistent with high stiffness promoting myofibroblast differentiation. Conclusion Primary cardiac fibroblasts acquire characteristics of matrifibrocytes in vitro when cultured for long time on plastic and in vivo in left ventricles of mice with pressure overload-induced congestive heart failure. Funding Acknowledgement Type of funding source: Public grant(s) – EU funding. Main funding source(s): Marie Sklodowska-Curie Individual Fellowship

Inhibition of collagen cross-linking: effects on fibrillar collagen and ventricular diastolic function

1995 ◽  
Vol 269 (3) ◽  
pp. H863-H868 ◽  
Author(s):  
S. Kato ◽  
F. G. Spinale ◽  
R. Tanaka ◽  
W. Johnson ◽  
G. Cooper ◽  
...  
Keyword(s):  
Ventricular Volume ◽  
Left Ventricular ◽  
Collagen Content ◽  
Distribution Area ◽  
Cross Linking ◽  
Fibrillar Collagen ◽  
Volume Data ◽  
Myocardial Stiffness ◽  
And Function ◽  
Collagen Cross Linking

The fibrillar collagen network is postulated to be a primary determinant of left ventricular diastolic stiffness. This hypothesis was tested by examining the structural and physiological effects of a reduction in fibrillar collagen content and cross-linking in the intact left ventricle. Collagen cross-linking was inhibited by treating five normal adult pigs with beta-aminopropionitrile (BAPN; 10 g/day po) for 6 wk; five normal untreated pigs served as controls. Left ventricular volume, mass, and function were determined by simultaneous echocardiography and catheterization. Chamber stiffness, defined by pressure vs. volume data, and myocardial stiffness, defined by stress vs. dimension data, were determined from variably loaded beats during dextran infusion. Collagen distribution (% area) and integrity (% confluence) were determined by light microscopy. Collagen content was measured by hydroxyproline assay, and collagen cross-linking was measured by salt extraction. BAPN decreased collagen distribution (% area decreased from 12 +/- 1% in control to 7 +/- 1% in BAPN, P < 0.05), collagen integrity (% confluence decreased from 8 +/- 1% in control to 4 +/- 1% in BAPN, P < 0.05), collagen content (from 36 +/- 2 mg/g dry wt in control to 27 +/- 2 mg/g dry wt in BAPN, P < 0.05), and collagen cross-linking (extractable collagen increased from 21 +/- 2% in control to 28 +/- 2% in BAPN, P < 0.05). BAPN decreased chamber stiffness (0.13 +/- 0.02 in control to 0.06 +/- 0.01 in BAPN, P < 0.05) and myocardial stiffness (10.4 +/- 0.5 in control to 6.6 +/- 0.5 in BAPN, P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Phenotypic characterization of primary cardiac fibroblasts from patients with HFpEF

PLoS ONE ◽  
2022 ◽  
Vol 17 (1) ◽  
pp. e0262479
Author(s):  
Yuhua Zhang ◽  
An O. Van Laer ◽  
Catalin F. Baicu ◽  
Lily S. Neff ◽  
Stanley Hoffman ◽  
...  
Keyword(s):  
Heart Failure ◽  
Cardiac Fibroblasts ◽  
Left Ventricular ◽  
Collagen I ◽  
Collagen Content ◽  
Treatment Modalities ◽  
Phenotypic Characterization ◽  
Fibrillar Collagen ◽  
Primary Fibroblast ◽  
Fibroblast Cultures

Heart failure is a leading cause of hospitalizations and mortality worldwide. Heart failure with a preserved ejection fraction (HFpEF) represents a significant clinical challenge due to the lack of available treatment modalities for patients diagnosed with HFpEF. One symptom of HFpEF is impaired diastolic function that is associated with increases in left ventricular stiffness. Increases in myocardial fibrillar collagen content is one factor contributing to increases in myocardial stiffness. Cardiac fibroblasts are the primary cell type that produce fibrillar collagen in the heart. However, relatively little is known regarding phenotypic changes in cardiac fibroblasts in HFpEF myocardium. In the current study, cardiac fibroblasts were established from left ventricular epicardial biopsies obtained from patients undergoing cardiovascular interventions and divided into three categories: Referent control, hypertension without a heart failure designation (HTN (-) HFpEF), and hypertension with heart failure (HTN (+) HFpEF). Biopsies were evaluated for cardiac myocyte cross-sectional area (CSA) and collagen volume fraction. Primary fibroblast cultures were assessed for differences in proliferation and protein expression of collagen I, Membrane Type 1-Matrix Metalloproteinase (MT1-MMP), and α smooth muscle actin (αSMA). Biopsies from HTN (-) HFpEF and HTN (+) HFpEF exhibited increases in myocyte CSA over referent control although only HTN (+) HFpEF exhibited significant increases in fibrillar collagen content. No significant changes in proliferation or αSMA was detected in HTN (-) HFpEF or HTN (+) HFpEF cultures versus referent control. Significant increases in production of collagen I was detected in HF (-) HFpEF fibroblasts, whereas significant decreases in MT1-MMP levels were measured in HTN (+) HFpEF cells. We conclude that epicardial biopsies provide a viable source for primary fibroblast cultures and that phenotypic differences are demonstrated by HTN (-) HFpEF and HTN (+) HFpEF cells versus referent control.

Abstract 277: Microrna-33 Promotes Cardiac Fibrosis by Maintaining Cellular Lipid Homeostasis

2016 ◽  
Vol 119 (suppl_1) ◽  
Author(s):  
Masataka Nishiga ◽  
Takahiro Horie ◽  
Yasuhide Kuwabara ◽  
Osamu Baba ◽  
Tetsushi Nakao ◽  
...  
Keyword(s):  
Cardiac Fibrosis ◽  
Cardiac Fibroblasts ◽  
Pressure Overload ◽  
Cholesterol Content ◽  
Atp Binding Cassette Transporter ◽  
Primary Fibroblasts ◽  
Proliferation In Vitro ◽  
Altered Lipid

Background: A highly conserved microRNA, miR-33 is considered as a potential therapeutic target for atherosclerosis, because recent reports, including ours, indicated miR-33 has atherogenic effects by reducing HDL-C. However, the functions of miR-33 in heart failure remain to be elucidated. Methods and results: To clarify the functions of miR-33 involved in cardiac hypertrophy and fibrosis in vivo, we investigated the responses to pressure overload by transverse aortic constriction (TAC) in miR-33 deficient (KO) mice. When subjected to TAC, miR-33 expression level was significantly up-regulated in wild-type (WT) left ventricles, whereas miR-33 KO hearts displayed no less hypertrophic responses than WT hearts. However, interestingly, histological and gene expression analyses showed ameliorated cardiac fibrosis in miR-33 KO hearts compared to WT hearts. Furthermore, we generated cardiac fibroblast specific miR-33 deficient mice, which also showed ameliorated cardiac fibrosis when they were subjected to TAC. We also found that cardiac fibroblasts were mainly responsible for miR-33 expression in the heart, because its expression was about 4-folds higher in isolated primary cardiac fibroblasts than cardiomyocytes. Deficiency of miR-33 impaired cell proliferation in primary fibroblasts, which was considered due to altered lipid raft cholesterol content by up-regulated ATP-binding cassette transporter A1/G1. Conclusion: Deficiency of miR-33 impaired fibroblast proliferation in vitro, and ameliorated cardiac fibrosis induced by pressure overload in vivo.

Abstract 292: TRPA1 Promoting Myofibroblast Differentiation Mediate Pressure Overload-Induced Cardiac Fibrosis

Circulation ◽  
2018 ◽  
Vol 138 (Suppl_2) ◽  
Author(s):  
Shuang Li ◽  
Dong Han ◽  
Dachun Yang
Keyword(s):  
Knockout Mice ◽  
Molecular Mechanisms ◽  
Cardiac Fibrosis ◽  
Transient Receptor Potential ◽  
Transforming Growth Factor ◽  
Ventricular Remodeling ◽  
Cardiac Fibroblasts ◽  
Gene Transfection ◽  
Pressure Overload

Background: Hypertensive ventricular remodeling is a common cause of heart failure. Activation and accumulation of cardiac fibroblasts is the key contributors to this progression. Our previous studies indicate that transient receptor potential ankyrin 1 (TRPA1), a Ca 2+ channel necessary and sufficient, play a prominent role in ventricular remodeling. However, the molecular mechanisms regulating remain poorly understood. Methods: We used TRPA1 agonists cinnamaldehyde (CA) pretreatment and TRPA1 knockout mice to understand the role of TRPA1 in ventricular remodeling of hypertensive heart. We also examine the mechanisms through gene transfection and in vitro experiments. Results: TRPA1 overexpression fully activated myofibroblast transformation, while fibroblasts lacking TRPA1 were refractory to transforming growth factor β (TGF-β) -induced transdifferentiation. TRPA1 knockout mice showed hypertensive ventricular remodeling reversal following pressure overload. We found that the TGF-β induced TRPA1 expression through calcineurin-NFAT-Dyrk1A signaling pathway via the TRPA1 promoter. Once induced, TRPA1 activates the Ca 2+ -responsive protein phosphatase calcineurin, which itself induced myofibroblast transdifferentiation. Moreover, inhibition of calcineurin prevented TRPA1-dependent transdifferentiation. Conclusion: Our study provides the first evidence that TRPA1 regulation in cardiac fibroblasts transformation in response to hypertensive stimulation. The results suggesting a comprehensive pathway for myofibroblast formation in conjunction with TGF-β, Calcineurin, NFAT and Dyrk1A. Furthermore, these data indicate that negative modulation of cardiac fibroblast TRPA1 may represent a therapeutic strategy against hypertensive cardiac remodeling.

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

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.

Role of sarcoplasmic reticulum in loss of load-sensitive relaxation in pressure overload cardiac hypertrophy

1994 ◽  
Vol 266 (1) ◽  
pp. H68-H78 ◽  
Author(s):  
C. R. Cory ◽  
R. W. Grange ◽  
M. E. Houston
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Cardiac Hypertrophy ◽  
Atpase Activity ◽  
Pressure Overload ◽  
Fold Increase ◽  
Left Ventricular ◽  
Isometric Tension ◽  
Tension Development ◽  
Sequestration Potential

The loss of load-sensitive relaxation observed in the pressure-overloaded heart may reflect a strategy of slowed cytosolic Ca2+ uptake to yield a prolongation of the active state of the muscle and a decrease in cellular energy expenditure. A decrease in the potential of the sarcoplasmic reticulum (SR) to resequester cytosolic Ca2+ during diastole could contribute to this attenuated load sensitivity. To test this hypothesis, both in vitro mechanical function of anterior papillary muscles and the SR Ca2+ sequestration potential of female guinea pig left ventricle were compared in cardiac hypertrophy (Hyp) and sham-operated (Sham) groups. Twenty-one days of pressure overload induced by coarctation of the suprarenal, subdiaphragmatic aorta resulted in a 36% increase in left ventricular mass in the Hyp. Peak isometric tension, the rate of isometric tension development, and the maximal rates of isometric and isotonic relaxation were significantly reduced in Hyp. Load-sensitive relaxation were significantly reduced in Hyp. Load-sensitive relaxation quantified by the ratio of a rapid loading to unloading force step in isotonically contracting papillary muscle was reduced 50% in Hyp muscles. Maximum activity of SR Ca(2+)-adenosinetriphosphatase (ATPase) measured under optimal conditions (37 degrees C; saturating Ca2+) was unaltered, but at low free Ca2+ concentrations (0.65 microM), it was decreased by 43% of the Sham response. Bivariate regression analysis revealed a significant (r = 0.84; P = 0.009) relationship between the decrease in SR Ca(2+)-ATPase activity and the loss of load-sensitive relaxation after aortic coarctation. Stimulation of the SR Ca(2+)-ATPase by the catalytic subunit of adenosine 3',5'-cyclic monophosphate-dependent protein kinase resulted in a 2.6-fold increase for Sham but only a 1.6-fold increase for Hyp. Semiquantitative Western blot radioimmunoassays revealed that the changes in SR Ca(2+)-ATPase activity were not due to decreases in the content of the Ca(2+)-ATPase protein or phospholamban. Our data directly implicate a role for decreased SR function in attenuated load sensitivity. A purposeful downregulation of SR Ca2+ uptake likely results from a qualitative rather than a quantitative change in the ATPase and possibly one of its key regulators, phospholamban.

Abstract P471: Mechanisms Controlling Regression Of Cardiac Fibrosis By Removal Of Pressure Overload

2021 ◽  
Vol 129 (Suppl_1) ◽  
Author(s):  
Lily Neff ◽  
An Van Laer ◽  
Catalin F Baicu ◽  
Michael R Zile ◽  
Amy Bradshaw
Keyword(s):  
Cardiac Fibrosis ◽  
Volume Fraction ◽  
Lysyl Oxidase ◽  
Cardiac Fibroblasts ◽  
Pressure Overload ◽  
Left Ventricular Pressure ◽  
Left Ventricular ◽  
Cellular Mechanisms ◽  
Cross Sectional ◽  
Fibroblast Activation

Background: Antecedent conditions, like aortic stenosis, can induce left ventricular pressure overload (LVPO), that can lead to Heart Failure with Preserved Ejection Fraction (HFpEF). Myocardial fibrosis and stiffness are key characteristics of HFpEF. Cardiac fibroblasts are the primary cell type regulating ECM production and deposition. In previous studies, biopsies isolated at the time of SAVR surgery, to correct stenosis, and then at 1-year and 5-years post-SAVR showed reductions in hypertrophy and fibrosis demonstrating these processes can regress. However, cellular mechanisms, including fibroblast activity, are poorly defined. Objective: Define mechanisms that contribute to remodeling of ECM before and after LVPO. Methods: LVPO was induced using transverse aortic constriction (TAC). LVPO was relieved by removal of the band (unTAC) at 4 wks. Cardiomyocyte cross-sectional area (CSA), collagen volume fraction (CVF), and protein production was measured by histology and immunoblot for five time points: nonTAC, 2wk TAC, 4wk TAC, 4wk TAC+2wk unTAC, and 4wk TAC+4wk unTAC. Results: In response to LVPO, myocyte CSA increased by 23% at 2wk TAC and by 47% at 4wk. CVF increased by 64% and 204% at 2wk and 4wk TAC, respectively, versus nonTAC. In 2wk TAC hearts, SMA, a marker of fibroblast activation was increased as was production of two collagen cross-linking enzymes, lysyl oxidase (LOX) and LOXL2, in the absence of significant increases in markers of ECM degradation. After unloading, myocyte CSA decreased by 20% in 2wk unTAC versus 4wk TAC and CVF decreased by 38% in 4wk unTAC versus 4wk TAC. Coincident with decreases in CVF, levels of pro-MMP2 increased at 2wk unTAC as did levels of degraded collagen measured by collagen hybridizing peptide reactivity. Whereas markers of ECM deposition, LOX and LOXL2, were not increased in unTAC myocardium, a resurgence of SMA production occurred in 2wk unTAC. Conclusions: In LVPO hearts, hypertrophy was characterized by increases in myocyte CSA, greater CVF, and fibroblast activation with increased production of pro-fibrotic ECM. After unloading, hypertrophy and fibrosis significantly decreased accompanied by increases in ECM degrading activity and reductions in proteins that contribute to collagen assembly.

Abstract 89: 17beta-Estradiol-activated Estrogen Receptors Attenuate Cardiac Fibrosis Through Inhibition of Collagen I and III Expression in Female Hearts

2016 ◽  
Vol 119 (suppl_1) ◽  
Author(s):  
Elke Dworatzek ◽  
Shokoufeh Mahmoodzadeh ◽  
Christina Westphal ◽  
Daniela Fliegner ◽  
Vera Regitz-Zagrosek
Keyword(s):  
Estrogen Receptors ◽  
Cardiac Fibrosis ◽  
Cardiac Fibroblasts ◽  
Pressure Overload ◽  
Left Ventricular ◽  
Collagen I ◽  
Sham Operation ◽  
Female Rat ◽  
Female Mice ◽  
Gene And Protein Expression

Objectives: Female pressure-overloaded hearts show less fibrosis compared with males. 17β-Estradiol (E2) attenuates cardiac fibrosis in female mice. Whether this is mediated by direct E2-effects on collagen synthesis is still unknown. Therefore, we investigated the role of E2 and estrogen receptors (ER) on collagen I and III expression and analyzed involved mechanisms. Methods: Female C57BL/6J mice (7 weeks) underwent sham operation, ovariectomy (OVX), OVX with E2-supplementation (390mg E2-containing pellets) or placebo. After 2 weeks, animals underwent transverse aortic constriction (TAC) or sham surgery. Mice were sacrificed after 9 weeks. Collagen amount, collagen I and III protein in left ventricular tissue were detected by Sirius Red and antibody staining, respectively. Gene and protein expression were determined by quantitative Real-Time PCR and Western blot. Adult female rat cardiac fibroblasts were treated with E2 (10 -8 M), vehicle, ERα- and β-agonists (10 -7 M) for 24h or pre-treated with PD98059 for 1h. ER binding to the collagen I and III promoter was analyzed by chromatin immunoprecipitation assays. Findings: In female OVX mice, undergoing TAC surgery, E2-supplementation significantly reduced collagen deposition, collagen I and III mRNA and protein levels in comparison with mice without E2. In female rat cardiac fibroblasts, E2 significantly down-regulated collagen I and III mRNA and protein level. Specific ER-agonist-treatment showed that E2-mediated regulation of collagen I and III expression was mediated via activation of ERα, but not ERβ. Further, upon E2-treatment, ERα was phosphorylated at Ser118, which occurred by E2-induced activation of ERK1/2 signaling. Furthermore, we could show that ERα and ERβ bind to two putative half-palindromic estrogen response elements within the collagen I and III promoter in female cardiac fibroblasts. Conclusion: E2 inhibits cardiac collagen I and III mRNA and protein in female mice under pressure overload. Data from rat female cardiac fibroblasts suggest that this is mediated via E2-activated ERK1/2 signaling and ERα, which binds with ERβ to the collagen I and III promoter. Understanding of how E2/ER attenuate collagen I and III expression in pathological hypertrophy may improve therapy.

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