Transforming growth factor-β-dependent Wnt secretion controls myofibroblast formation and myocardial fibrosis progression in experimental autoimmune myocarditis

• Published in: European heart journal 2017-05, Vol.38 (18), p.1413-1425
• Main Authors: Blyszczuk, Przemyslaw, Müller-Edenborn, Björn, Valenta, Tomas, Osto, Elena, Stellato, Mara, Behnke, Silvia, Glatz, Katharina, Basler, Konrad, Lüscher, Thomas F, Distler, Oliver, Eriksson, Urs, Kania, Gabriela
• Format: Article
• Language: English
• Subjects: Animals; Autoimmune Diseases - etiology; Benzeneacetamides - pharmacology; beta Catenin - metabolism; Cell Differentiation - physiology; Disease Progression; Fibrosis - physiopathology; Humans; MAP Kinase Kinase Kinases - metabolism; MAP Kinase Kinase Kinases - physiology; Membrane Proteins - metabolism; Mice, Inbred BALB C; Myocarditis - etiology; Myocardium - pathology; Myofibroblasts - physiology; Pyridines - pharmacology; Signal Transduction - physiology; Stem Cells - physiology; TCF Transcription Factors - metabolism; Transforming Growth Factor beta - physiology; Ventricular Dysfunction - physiopathology; Wnt Proteins - metabolism; Wnt-5a Protein - metabolism; Wnt1 Protein - metabolism
• ISSN: 0195-668X; 1522-9645
• DOI: 10.1093/eurheartj/ehw116

Myocardial fibrosis critically contributes to cardiac dysfunction in inflammatory dilated cardiomyopathy (iDCM). Activation of transforming growth factor-β (TGF-β) signalling is a key-step in promoting tissue remodelling and fibrosis in iDCM. Downstream mechanisms controlling these processes, remain elusive. Experimental autoimmune myocarditis (EAM) was induced in BALB/c mice with heart-specific antigen and adjuvant. Using heart-inflammatory precursors, as well as mouse and human cardiac fibroblasts, we demonstrated rapid secretion of Wnt proteins and activation of Wnt/β-catenin pathway in response to TGF-β signalling. Inactivation of extracellular Wnt with secreted Frizzled-related protein 2 (sFRP2) or inhibition of Wnt secretion with Wnt-C59 prevented TGF-β-mediated transformation of inflammatory precursors and cardiac fibroblasts into pathogenic myofibroblasts. Inhibition of T-cell factor (TCF)/β-catenin-mediated transcription with ICG-001 or genetic loss of β-catenin also prevented TGF-β-induced myofibroblasts formation. Furthermore, blocking of Smad-independent TGF-β-activated kinase 1 (TAK1) pathway completely abrogated TGF-β-induced Wnt secretion. Activation of Wnt pathway in the absence of TGF-β, however, failed to transform precursors into myofibroblasts. The critical role of Wnt axis for cardiac fibrosis in iDCM is also supported by elevated Wnt-1/Wnt-5a levels in human samples from hearts with myocarditis. Accordingly, and as an in vivo proof of principle, inhibition of Wnt secretion or TCF/β-catenin-mediated transcription abrogated the development of post-inflammatory fibrosis in EAM. We identified TAK1-mediated rapid Wnt protein secretion as a novel downstream key mechanism of TGF-β-mediated myofibroblast differentiation and myocardial fibrosis progression in human and mouse myocarditis. Thus, pharmacological targeting of Wnts might represent a promising therapeutic approach against iDCM in the future.