SUN-002 eNOS/NO pathway underlies the mechanisms of AKI to CKD transition via prolonged activatio of Wnt/βcatenin pathway

Abstract

Acute kidney injury (AKI) is not always reversible, but often promotes to chronic kidney disease (CKD), known as “AKI to CKD transition.” Aging and disease conditions such as hypertension and diabetes are recognized as risk factors for AKI to CKD transition. These conditions are also closely associated with endothelial dysfunction (ED). Therefore, we hypothesized that AKI to CKD transition is promoted by ED characterized by deterioration in eNOS/Nitric Oxide (NO) /sGC/PKG pathway. Wild-type mice (C57B6/J: WT) and eNOS deficient mice (eNOSKO) were used. WT and eNOSKO mice were divided into 4 groups: WT-sham, WT-IRI, eNOSKO-sham and eNOSKO-IRI. Mice were sacrificed on day 28 (D28) after ischemic reperfusion injury(IRI)(WT-IRI-D28 and eNOSKO-IRI-D28). To evaluate the therapeutic potential of sGC activation on the AKI to CKD transition, eNOSKO-IRI mice treated with PDE5 inhibitor (PDE5i, Sildenafil citrate, 5mg/kg/day, drinking water)from day 7 (D7) to D28 after IRI. Acute kidney damages of IRI were fully recovered in WT-IRI-D28 group. However, tubulointerstitial injuries, tubular cell damage, interstitial fibrosis and infiltration of inflammatory cells remained in eNOSKO-IRI-D28 group. These results indicate that deficient eNOS/NO/sGC/PKG signaling pathwaypromotes AKI to CKD transition after IRI. Next, the kidney damages in the early phase, day 1 and day 7, after IRI were examined in both groups. Histological examinations of kidney tissues failed to detect alterations in both groups at day 1 and day 7. However, RNA-seq data revealed significant increased expressions of Wnt/βcatenin‒related genes and M2 macrophages related gene were detected in eNOSKO-IRI-D7 group compared with WT-IRI-D7 group. In addition infiltration of M2 macrophages which were detected by flow cytometry, were increased in eNOSKO-IRI-D7 but not WT-IRI-D7. Furthermore, PDE5i treatment significantly ameliorated the kidney injuries compared with non-treated group. Endothelial dysfunction, characterized by deterioration of eNOS/NO/sGC/PKG signaling pathway underlies prolonged activation of Wnt/βcatenin pathway, thereby plays a pivotal role in AKI to CKD transition.