Therapeutic Inhibition of HIF2a Reduces Cardiac Fibrosis in Heart Failure

Background: Cardiac fibrosis remains a major clinical burden with limited therapeutic options. Endothelial-to-mesenchymal transition (EndoMT) is a process in which endothelial cells transform into fibroblasts, inducing myocardial fibrosis in heart failure. Cell fate transitions are dependent on metabolic changes. During transition of endothelial cells to fibroblasts, hypoxia-inducible factor 2 α (HIF2a) acts as critical mediator of a metabolic switch. We hypothesized that inhibition of HIF2a (a) prevents endothelial-to-mesenchymal transition and hence, (b) ameliorates cardiac fibrosis in heart failure.

Methods: EndoMT was induced in human coronary endothelial cells by treatment with TGF-β and angiotensin II. Cellular metabolism was detected via Seahorse Flux Analysis. Endothelial function was confirmed via tube formation assay. EndoMT was detected via immunofluorescence staining. HIF2a was inhibited during EndoMT using the specific inhibitor PT2385 and translation inhibitor C76. In vivo, non-ischemic heart failure was induced in C57Bl6 mice and Cdh5-Cre/tdTomato mice by subcutaneous implantation of osmotic pumps delivering angiotensin II and concomitant administration of NaCl and eNOS-inhibitor L-NAME in drinking water for 4 weeks. HIF2a translation inhibitor C76 was administered via intraperitoneal injection for 4 weeks. Heart function was assessed via echocardiography and cardiac fibrosis was assessed histologically. tdTomato-labeled cells were isolated from hearts of Cdh5-Cre lineage tracing mice and tested for endothelial function and mesenchymal transition.

Results: EndoMT leads to metabolic changes with impaired mitochondrial function and increased protein expression of HIF2a in coronary artery endothelial cells. Inhibition of HIF2a protein translation prevents EndoMT and preserves endothelial gene expression and function. Inhibition of the canonical HIF2a pathway shows no effect on EndoMT, indicating a non-canonical function of HIF2a in endothelial cell fate transition. In vivo blockage of HIF2a reduces cardiac fibrosis and improves heart function in a murine non-ischemic heart failure model. In vivo lineage tracing of endothelial cells in Cdh5-Cre/tdTomato mice reveals that blocking HIF2α effectively prevents endothelial-to-mesenchymal transition.

Conclusion: HIF2a plays a major role in endothelial-to-mesenchymal transition via a non-canonical signaling pathway. Inhibition of HIF2a might become a potent therapeutic option to counteract myocardial fibrosis in heart failure.

Publication History

Article published online:
11 February 2025