Activated Protein C (PC)-Based Therapeutics Enhance Tubular Regeneration in Diabetic Kidney Disease

Background: Acute on chronic renal injury (ACRI) is a major health problem. Tubulointerstitial damage in diabetic kidney disease (DKD) impairs the outcome of acute kidney injury (AKI), possibly reflecting an exhaustion of the renal regenerative capacity in DKD. The role of activated PC (aPC), which protects against DKD progression and reverses glucose-induced tubular senescence, for renal regeneration after AKI has not been elucidated. Methods: A model of ACRI was established in mice with persistent hyperglycemia followed by ischemia-reperfusion injury (IRI). Control mice were compared to mice pre-treated with aPC or parmodulin-2 (a small molecule mimicking aPC’s cytoprotective signaling). Lineage tracing and single nuclear RNA sequencing (snRNA-seq) were performed to identify the possible mechanisms. Ex vivo analyses of mouse tissues and primary cells were conducted to confirm the findings. Results: DKD markedly aggravated histopathological changes and functional impairment in the acute phase (48 hours) following IRI. Pre-treatment with aPC or parmodulin-2 conveyed renal protection. Lineage tracing studies revealed increased expansion of proximal tubular cell clones upon aPC pre-treatment. snRNA-seq showed marked changes in different cell populations in DKD mice subjected to IRI. Functional annotations revealed that both aPC and parmodulin-2 reduced ferroptosis and oxidative stress in proximal tubular cells, fibroblasts and endothelial cell clusters. Furthermore, both treatments induced survival pathways and cell cycle progression in proximal tubules. This protective phenotype was confirmed by reduced cell cycle arrest and increased proliferation markers of tubular cells ex vivo. Conclusion: aPC and parmodulin-2 improve the outcome of ACRI by reducing the oxidative stress and enhancing the regenerative capacity of renal tubular cells. Therefore, aPC-based therapeutics may provide innovative approaches to ACRI in patients with pre-existing DKD. Funding: Government Support – Non-U.S.