Heparin Prevents AKI to CKD Transition via HDAC1-Mediated Deacetylation of p65 Exerting Anti-inflammatory Effect Independent from Its Anticoagulant Properties

Background: The long-term outcome of acute kidney injury (AKI) is not good, since the survivors of AKI are prone to developing chronic kidney disease (CKD). Chronic inflammation is recognized as a pivotal determinant in the transition from AKI to CKD. Heparin, an anticoagulant, exhibits anti-inflammation/anti-complement activities, whose role in AKI to CKD transition remain elusive. Methods: C57/B6 mice were subjected to unilateral renal ischemia-reperfusion (uIR) and folic acid (FA) intervention to construct AKI to CKD mouse models with or without low doses heparin(5 units/mouse) and its chemically modified variant lacking anticoagulant properties (N-Acetyl heparin sodium salt, NAH：200μg/mouse) treatment. Potential mechanism of heparin was investigated by bulk RNA-seq analysis. Downstream target of heparin was screened in Swiss Target Prediction database, and detected by drug affinity responsive target stability (DARTS) analysis and cellular thermal shift assay (CETSA). BUMPT cells were used to further validate the effect and target of heparin and NAH in vitro. Results: Treatment of low doses of heparin and its non-anticoagulant derivatives (NAH) significantly alleviated the uIR- and FA-induced renal tubular injury, and tubulointerstitial fibrosis, and improved renal function. Bulk RNA-seq analysis claimed that heparin might downregulate inflammatory pathways, including cytokine-cytokine receptor interaction, and MAPK signaling pathway, which were confirmed by decreasing immune cell infiltration and inflammatory cytokine expression in heparin-treated mice. Mechanistically, heparin and NAH bound to histone deacetylase 1 (HDAC1) independent on anticoagulant active sites in renal tubular epithelial cells and reduced the level of acetylated p65, leading to decreased expression of inflammatory factors. Conclusion: Heparin and its non-anticoagulant derivatives inhibited inflammation by targeting HDAC1 to reduce the acetylation of p65. They inhibited the AKI to CKD transition, which could be potentially developed as a novel therapy for preventing AKI to CKD progression. Funding: Government Support – Non-U.S.