Abstract 121: Interleukin 11 Mediates Wnt/β-catenin-dependent Fibrotic Response Of Human Cardiac Fibroblasts

Abstract

Wnt proteins family represents secreted glycoproteins implicated in the number of fibrotic cardiac pathologies. The transcriptional activity of Wnts is broad and involves β-catenin-dependent or β-catenin-independent responses. In this study, we examined the effect of exogenous Wnt3a (β-catenin-dependent) and Wnt5a (β-catenin-independent) in TGF-β-activated human cardiac fibroblasts. Furthermore, we assessed the hypothesis that Wnt3a could regulate IL-11 production and analyzed its contribution to profibrotic response in cardiac fibroblasts.By employing a full genome transcriptomics, we analyzed transformation of human cardiac fibroblasts induced by TGF-β in the presence of Wnt3a or Wnt5a produced by cell culture supernatant of L-Wnt3a, L-Wnt5a or control L-cells. Stimulation with Wnt3a of TGF-β-activated fibroblasts resulted in induction of 66 genes, specifically involved in myofibroblast differentiation including ACTA2 (encoding alpha smooth muscle actin; αSMA) ACTG2 (encoding gamma smooth muscle actin; γSMA) and VCL (encoding vinculin). In contrast to Wnt3a, treatment with Wnt5a upregulated expression of only 2 genes in TGF-β-activated cells. Additionally, in the presence of TGF-β, Wnt3a enhanced phosphorylation of TAK1 and production and secretion of IL-11. Importantly, in the absence of TGF-β, Wnt3a did not promote fibroblast-to-myofibroblast transition, TAK1 phosphorylation and IL-11 production. To determine, if Wnt3a-dependent production of IL-11 could contribute to profibrotic response we blocked IL-11 activity with anti-IL-11 neutralizing antibody in cardiac fibroblasts activated with TGF-β and Wnt3a. We found that neutralizing anti-IL11 antibody effectively suppressed production of αSMA, γSMA, fibronectin and pro-collagen I alpha 1, both on mRNA and protein levels. In line with these findings, blockade of IL-11 suppressed contractile properties of TGF-β/Wnt3a-activated cardiac fibroblasts. In conclusion, Wnt3a and Wnt5a differentially regulate gene expression of TGF-β-activated cardiac. Activation of the Wnt/β-catenin pathway promotes fibroblast-to-myofibroblast transition by enhancing production of profibrotic IL-11. It seems that identifying the profibrotic Wnt/β-catenin-IL11 mechanism in cardiac fibroblasts might represent a promising strategy in development of new therapies against cardiac fibrosis.