Hypoxia-inducible factor activation promotes osteogenic transition of valve interstitial cells and accelerates aortic valve calcification in a mice model of chronic kidney disease

Abstract

IntroductionValve calcification (VC) is a widespread complication in chronic kidney disease (CKD) patients. VC is an active process with the involvement of in situ osteogenic transition of valve interstitial cells (VICs). VC is accompanied by the activation of hypoxia inducible factor (HIF) pathway, but the role of HIF activation in the calcification process remains undiscovered.Methods and resultUsing in vitro and in vivo approaches we addressed the role of HIF activation in osteogenic transition of VICs and CKD-associated VC. Elevation of osteogenic (Runx2, Sox9) and HIF activation markers (HIF-1α and HIF-2α) and VC occurred in adenine-induced CKD mice. High phosphate (Pi) induced upregulation of osteogenic (Runx2, alkaline-phosphatase, Sox9, osteocalcin) and hypoxia markers (HIF-1α, HIF-2α, Glut-1), and calcification in VICs. Down-regulation of HIF-1α and HIF-2α inhibited, whereas further activation of HIF pathway by hypoxic exposure (1% O2) or hypoxia mimetics [desferrioxamine, CoCl2, Daprodustat (DPD)] promoted Pi-induced calcification of VICs. Pi augmented the formation of reactive oxygen species (ROS) and decreased viability of VICs, whose effects were further exacerbated by hypoxia. N-acetyl cysteine inhibited Pi-induced ROS production, cell death and calcification under both normoxic and hypoxic conditions. DPD treatment corrected anemia but promoted aortic VC in the CKD mice model.DiscussionHIF activation plays a fundamental role in Pi-induced osteogenic transition of VICs and CKD-induced VC. The cellular mechanism involves stabilization of HIF-1α and HIF-2α, increased ROS production and cell death. Targeting the HIF pathways may thus be investigated as a therapeutic approach to attenuate aortic VC.

High glucose promotes osteogenic differentiation of human lens epithelial cells through hypoxia‐inducible factor (HIF) activation

“…It is increasingly clear that hypoxia and HIF‐1 activation are involved in the osteogenic phenotype switch and calcification of VSMCs and VICs (Balogh et al, 2019; Csiki et al, 2023; Mokas et al, 2016; Tóth et al, 2022). In accordance with that here, we showed that calcification of HuLECs is attenuated in the absence of HIF‐1α or HIF‐2α, suggesting that hyperglycaemia‐induced stabilisation of HIF‐1α and HIF‐2α and subsequent activation of the HIF‐1 pathway plays a critical role in HG‐induced promotion of calcification (Figure 4).…”

“…A previous study showed that HG induces HIF-1α stabilisation in LECs (Han et al, 2015) and because HIF pathway activation was shown to be associated with the promotion of vascular and valve calcification (Balogh et al, 2019;Csiki et al, 2023;Mokas et al, 2016), we next investigated whether this mechanism is involved in the HG-induced promotion of calcification in HuLECs. To address this, we treated HuLECs with OM (2.5 mmol/L Pi, 0.3 mmol/L Ca, 48 h) under NG and HG conditions.…”

“…Recent findings have suggested that activation of the hypoxia‐inducible factor (HIF) pathway promotes osteogenic differentiation of VSMCs as well as valve interstitial cells (VICs) (Balogh et al, 2019; Csiki et al, 2023; Mokas et al, 2016; Tóth et al, 2022). Hyperglycaemia has been associated with HIF‐1α stabilisation and subsequent HIF pathway activation in diverse cell types including LECs (Han et al, 2015).…”

Vascular Calcification: Molecular Networking, Pathological Implications and Translational Opportunities

“…Hypoxia within the vascular microenvironment can trigger signaling cascades that contribute to the differentiation of VSMCs toward a chondrogenic phenotype [ 59 ]. The mechanisms underlying VSMC calcification under hypoxic conditions require either hypoxia-inducible factor (HIF) activation or the production of mitochondrial-derived reactive oxygen species (ROS) [ 60 , 61 ]. High levels of inorganic phosphate (Pi) increase VSMC migration and calcification and are related to impaired Pi/calcium balance and miR-223 involvement, whereas TGF-β/Smad3 signaling plays an inhibitory role in Pi-induced VSMC calcification [ 62 , 63 , 64 ].…”