B-Type Natriuretic Peptide Exerts Broad Functional Opposition to Transforming Growth Factor-β in Primary Human Cardiac Fibroblasts

Abstract

Abstract-The natriuretic peptides, including human B-type natriuretic peptide (BNP), have been implicated in the regulation of cardiac remodeling. Because transforming growth factor-␤ (TGF-␤) is associated with profibrotic processes in heart failure, we tested whether BNP could inhibit TGF-␤-induced effects on primary human cardiac fibroblasts. BNP inhibited TGF-␤-induced cell proliferation as well as the production of collagen 1 and fibronectin proteins as measured by Western blot analysis. cDNA microarray analysis was performed on RNA from cardiac fibroblasts incubated in the presence or absence of TGF-␤ and BNP for 24 and 48 hours. TGF-␤, but not BNP, treatment resulted in a significant change in the RNA profile. BNP treatment resulted in a remarkable reduction in TGF-␤ effects; 88% and 85% of all TGF-␤-regulated mRNAs were affected at 24 and 48 hours, respectively. BNP opposed TGF-␤-regulated genes related to fibrosis (collagen 1, fibronectin, CTGF, PAI-1, and TIMP3), myofibroblast conversion (␣-smooth muscle actin 2 and nonmuscle myosin heavy chain), proliferation (PDGFA, IGF1, FGF18, and IGFBP10), and inflammation (COX2, IL6, TNF␣-induced protein 6, and TNF superfamily, member 4). Lastly, BNP stimulated the extracellular signal-related kinase pathway via cyclic guanosine monophosphate-dependent protein kinase signaling, and two mitogen-activated protein kinase kinase inhibitors, U0126 and PD98059, reversed BNP inhibition of TGF-␤-induced collagen-1 expression. These findings demonstrate that BNP has a direct effect on cardiac fibroblasts to inhibit fibrotic responses via extracellular signal-related kinase signaling, suggesting that BNP functions as an antifibrotic factor in the heart to prevent cardiac remodeling in pathological conditions. Key Words: B-type natriuretic peptide Ⅲ transforming growth factor-␤ Ⅲ cardiac fibroblasts Ⅲ fibrosis N atriuretic peptides comprise a family of vasoactive hormones that play important roles in the regulation of cardiovascular and renal homeostasis. [1][2][3] Atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) are predominantly produced in the heart and exert vasorelaxant, natriuretic, and antigrowth activities. Binding of ANP and BNP to type-A natriuretic peptide receptor (NPRA) leads to the generation of cyclic guanosine monophosphate (cGMP), which mediates most biological effects of the peptides. Mice lacking NPRA exhibit cardiac hypertrophy, fibrosis, hypertension, and increased expression of fibrotic genes, including TGF␤1, TGF␤3, and collagen 1. 4 -6 Furthermore, targeted disruption of the BNP gene in mice results in cardiac fibrosis and enhanced fibrotic response to ventricular pressure overload, suggesting that BNP is involved in cardiac remodeling. 7 Cardiac remodeling is viewed as a key determinant of the clinical outcome in heart disease. It is characterized by a structural rearrangement of the cardiac chamber wall that involves cardiomyocyte hypertrophy, fibroblast proliferation, and increased deposition of extracellular matrix (ECM) pro...

Inhibition of cardiac myofibroblast formation and collagen synthesis by activation and overexpression of adenylyl cyclase

“…TGF-␤ treatment is known to enhance the profibrotic state by altering expression of proteins such as plasminogen activator inhibitor (PAI-1) and IL-6 (28,29). Consistent with the ability of increased AC expression to blunt collagen synthesis, overexpression of AC6 decreased basal and TGF-␤-regulated expression of PAI-1 by 89 Ϯ 3% and 59 Ϯ 8%, respectively, and IL-6 by 81 Ϯ 2% and 92 Ϯ 3%, respectively.…”

Inhibition of Signal Transducer and Activator of Transcription 3 (STAT3) Attenuates Interleukin-6 (IL-6)-induced Collagen Synthesis and Resultant Hypertrophy in Rat Heart

“…Furthermore, lysyl oxidase (LOX) is also instrumental during collagen biogenesis that catalyzes lysine-derived cross-bridges between two or more lysine residues of nascent procollagen peptides during their maturation into collagen molecules (5, 7). Altered and deregulated expression of these factors has been demonstrated in failing myocardium (5).Involvement of various neurohumoral and growth factors has also been illustrated in the development of cardiac fibrosis both in vitro and in vivo (3,8). Cellular cross-talk between AngII-treated cardiomyocytes and fibroblasts has been shown to play an important role during collagen up-regulation with involvement of IL-6 during fibrosis (8 -10).…”

“…Involvement of various neurohumoral and growth factors has also been illustrated in the development of cardiac fibrosis both in vitro and in vivo (3,8). Cellular cross-talk between AngII-treated cardiomyocytes and fibroblasts has been shown to play an important role during collagen up-regulation with involvement of IL-6 during fibrosis (8 -10).…”

Myocardial Gene Expression Associated with Genetic Cardiac Hypertrophy in the Absence of Hypertension

“…It was of interest that transforming growth factor-β (TGF-β) was under-expressed in young HHR. A recent study has shown that human B-type natriuretic peptide (BNP) inhibits TGF-β-induced effects on primary human cardiac fibroblasts, including down-regulating TGF-β-regulated genes related to fibrosis, myofibroblast conversion, proliferation, and inflammation (33). The mouse homologue to the polypeptide hormone BNP, natriuretic peptide precursor type B (Nppb), was over-expressed in both young and old HHR, and several matrix/structural protein-related genes (β-actin, Actb; procollagen-5, Col5a1; cartilage associated protein, Crtap) were under-expressed in young HHR.…”