Fibrotic scarring drives the progression of heart failure after myocardial infarction (MI). Therefore, the development of specific treatment regimens to counteract fibrosis is of high clinical relevance. The transcription factor sex-determining region Y box 9 (SOX9) functions as an important regulator during embryogenesis, but recent data point toward an additional causal role in organ fibrosis. We show here that SOX9 is upregulated in the scar after MI in mice. Fibroblast-specific deletion of Sox9 ameliorated MI-induced left ventricular dysfunction, dilatation, and myocardial scarring in vivo. Unexpectedly, deletion of Sox9 also potently eliminated persisting leukocyte infiltration of the scar in the chronic phase after MI. RNA-Seq from the infarct scar revealed that Sox9 deletion in fibroblasts resulted in strongly downregulated expression of genes related to extracellular matrix, proteolysis, and inflammation. Importantly, Sox9 deletion in isolated cardiac fibroblasts in vitro similarly affected gene expression as in the cardiac scar and reduced fibroblast proliferation, migration, and contraction capacity. Together, our data demonstrate that fibroblast SOX9 functions as a master regulator of cardiac fibrosis and inflammation and might constitute a novel therapeutic target during MI.
Gesine M. Scharf, Katja Kilian, Julio Cordero, Yong Wang, Andrea Grund, Melanie Hofmann, Natali Froese, Xue Wang, Andreas Kispert, Ralf Kist, Simon J. Conway, Robert Geffers, Kai C. Wollert, Gergana Dobreva, Johann Bauersachs, Joerg Heineke
Guidelines: The Editorial Board will only consider letters that we deem relevant and of interest to our readers. We will not post data that have not been subjected to peer review, nor will we post letters that are essentially a reiteration of another letter. We reserve the right to edit any letter for length, content, and clarity. Authors will be notified by e-mail if their letters were accepted. No appeals will be considered.
Specific requirements: All letters must be 400 words or fewer. You may enter the letter as plain text or HTML. The author's name and e-mail address are required, and will be posted with the letter. All possible conflicts of interest must be noted, even if they are not posted. If you wish to include a figure (keep in mind that non-peer-reviewed data will not be posted), please contact the editors directly at email@example.com.