The prolyl-hydroxylase inhibitior Roxadustat upregulates HIF-1alpha and is associated with improved cardiac repair after myocardial infarction in mice

Abstract Introduction Activation of the CXCL12/CXCR4-axis is known to aid myocardial repair by attraction of reparative CXCR4+ cells through ischemia triggered hypoxia-inducible factor-1α (HIF-1α) activation of CXCL12 (1). To prolongate upregulation of CXCL12 we aimed to stabilize HIF-1α by administration of Roxadustat, the only prolyl hydroxylase inhibitor (PHI) clinically approved by the EMA with the purpose to augment myocardial remodelling and improve LV function. Methods To analyse the effects of HIF-1α mediated CXCL12 upregulation in vivo (BM & heart), optimal doses (50mg/kg i.p., every 72h) of the PHI Roxadusat (FG-4592) were administered to Bl6/J mice. CXCL12 and CXCR4 expression was analysed in-vitro in human umbilical vascular endothelial cells (HUVEC) after administration of FG-4592 (20µM to 1000µM) at different time points (1 to 24 hrs). Western Blots were performed and effects on HIF-1α -signalling were quantified by densitometry. We induced MI in BL6/J mice at the age of 8-10 weeks by LAD-ligation. Two groups (n=10) were treated with Roxadustat or saline for 28 days before assessment of cardiac function by echocardiography and evaluation by histology. Two other groups of n=5 mice were treated with Roxadustat or saline for one week and analysed regarding apoptotic-index by automated cell count in DAPI & Tunel stained sections. Results We were able to show a significant upregulation of HIF-1α after exposure of 50-500 μM Roxadustat for 4-24 hours in-vitro (HUVEC) and in-vivo (murine BL6/J hearts). Moreover, administration of 500 µM Roxadustat induced marked activation of CXCR4 and CXCL12, respectively. Infarct size (19.07%±7.86 vs. 24.14%±12,05; n= 10/8; p = 0.297), as well as LV-wall thickness in the infarcted myocardium (788.27µm±240.10 vs. 651.40µm±231.47; n=10/8; p = 0.240) revealed no significant differences 28 days after MI. Automated cell counting in the borderzone revealed a lowered apoptotic-index of Roxadustat treated animals (3.7%±1.1 vs. 6.3%±2.3; p = 0.071). Echocardiographic analyses showed a significantly preserved ejection fraction (EF) (46.1%±6.0 vs. 30.5%±9.3; n=10/9; p<0.001), reduced diastolic (4.18±0.32 vs. 4.77±0.40; p=0.002) and systolic (3.23±0.31 vs. 3.95±0.43; p<0.001) LV diameters in Roxadustat treated mice 28 days after MI compared to saline treated controls. Conclusion The clinically approved PHI Roxadustat revealed increased expression of HIF-1α associated with upregulation of CXCR4 and CXCL12. Administration of Roxadustat after MI revealed attenuated infarct remodelling and functional improvement showing its potential in ischemic heart disease.