Cardiomyocyte-Restricted Expression of IL11 Causes Cardiac Fibrosis, Inflammation, and Dysfunction
Background: Cardiac fibrosis is a common pathological process in heart disease and represents a therapeutic target. TGFß is the canonical driver of cardiac fibrosis and was recently shown to be dependent on IL11 for its profibrotic effects in fibroblasts. In the opposite direction, recombinant human IL11 has been reported as anti-fibrotic and also anti-inflammatory in the mouse heart. Objectives: In this study, we determined the effects of IL11 expression in cardiomyocytes on cardiac pathobiology and function. Methods: We used the Cre-loxP system to generate a tamoxifen-inducible mouse with cardiomyocyte-restricted murine Il11 expression. Using protein assays, bulk RNA-sequencing and in vivo imaging we analysed the effects of IL11 on myocardial fibrosis, inflammation and cardiac function and challenge previous reports suggesting cardioprotective potential of IL11. Results: TGFß stimulation of cardiomyocytes caused Il11 upregulation. As compared to wild-type controls, Il11 expressing hearts demonstrated severe cardiac fibrosis and inflammation that was associated with the upregulation of cytokines, chemokines, complement factors and increased inflammatory cells. IL11 expression also activated a programme of endothelial-to-mesenchymal transition and resulted in left ventricular dysfunction. Conclusion: Our data define species-matched IL11 as strongly profibrotic and proinflammatory when secreted from cardiomyocytes and further establish IL11 as a disease factor. Overall design: We extracted RNA and performed RNA-sequencing on myocardial samples from male and female tamoxifen inducible cardiomyocyte specific Il11 expressing mice and compared this to control samples  1, 3 and 6 weeks after induction of Il11 expression.