The anti-diabetic hormone glucagon-like peptide-1 induces formation of new elastic fibers in human cardiac fibroblasts after cross-activation of IGF-1R.

Glucagon-like peptide 1 (GLP-1) is a metabolic hormone involved in the stimulation of insulin biosynthesis and secretion. It has been recently reported that GLP-1 also exerts cardioprotective effects and facilitates functional recovery after myocardial infarction through GLP-1 receptor-mediated signaling in cardiomyocytes. GLP-1 treatment has been also demonstrated to produce sustained improvement in cardiac function in long-term studies, suggesting the involvement of mechanisms beyond the acute metabolic and cytoprotective effects. For example, the possible interaction of GLP-1 with the cardiac fibroblasts, which are responsible for the post-infarct remodeling and extracellular matrix (ECM) production, has not been previously explored. Here, we report that cultures of human cardiac fibroblasts treated with GLP-1 peptides display a selective up-regulation in elastin gene expression and a consequent increase in elastic fibers production, in the absence of the classic GLP-1R. Importantly, we provide experimental evidence that this GLP-1-induced elastogenesis is triggered through the cross-activation of the IGF-1R. Since GLP-1 does not stimulate deposition of collagen I, nor promote the proliferation or apoptosis of cultured cardiac fibroblasts, we speculate that its elastogenic effect may also contribute to the beneficial remodelling of the human heart following myocardial infarction.