Endothelial prolyl hydroxylase 3 mitigates maladaptive inflammation to promote post-ischemic kidney repair.

INTRODUCTION: Acute kidney injury (AKI) is a major health concern and well-established risk factor for the development of chronic kidney disease (CKD). Tissue hypoxia is a prominent feature of the injured kidney that shapes the biological behavior of parenchymal and immune cells. Endothelial cells have important immunomodulatory roles, but the impact of dysregulated oxygen sensing on their responses remains poorly understood.

METHODS: To investigate the role of endothelial oxygen sensing in AKI, we leveraged a combination of conditional mouse strains, single cell analyses of mouse and human samples, and complementary in vitro models. Specifically, we examined the impact of endothelial-specific inactivation of prolyl hydroxylase (PHD)1 or PHD3 in post-ischemic kidneys (ischemia/reperfusion model) and subsequently assessed the contribution of hypoxia inducible factor (HIF) signaling in the setting of endothelial PHD3 loss using genetic and mechanistic approaches.

RESULTS: Across two independent human datasets, endothelial PHD3 upregulation emerged as a consistent AKI signature, highlighting its clinical relevance. Post-ischemic inactivation of endothelial PHD3, but not PHD1, leads to maladaptive kidney repair in mice, characterized by increased fibrosis and inflammation. scRNA-seq analysis of the post-ischemic endothelial PHD3-haplodeficient kidney showed an endothelial interferon-γ gene signature, resembling the responses seen in patients with severe AKI. In vitro, both loss- and gain-of-function experiments demonstrated that PHD3 regulated interferon-γ-responsive pro-inflammatory signatures in an HIF-dependent manner. Consistent with this, simultaneous deletion of aryl hydrocarbon receptor nuclear translocator, the obligatory binding partner for HIF-α, restored kidney repair in endothelial PHD3-deficient mice.

CONCLUSIONS: Our findings identified endothelial PHD3 as a critical oxygen sensor that protected the kidney against maladaptive post-ischemic inflammation. By suppressing excessive interferon-γ-driven endothelial activation, PHD3 promoted tissue repair and limited the AKI-to-CKD transition, highlighting potential therapeutic avenues for mitigating disease progression.