Esculetin Attenuates Inflammation and Fibrosis to Prevent AKI-to-CKD Transition in Adenine-Induced Renal Injury by Inhibiting the EGFR/SRC/PI3K/AKT/NF-κB Signaling Axis

Background: Chronic kidney disease (CKD) is characterized by irreversible structural damage and functional deterioration of the kidneys. Esculetin (ES), with its anti-inflammatory, antioxidant, and immunomodulatory activities, shows potential in delaying renal function decline. This study aimed to investigate the protective effect of ES on adenine-induced CKD in mice and its underlying molecular mechanism, with a focus on its role in preventing the transition from acute kidney injury (AKI) to CKD. Methods: A AKI-to-CKD transition mice model was established by feeding mice a 0.2% adenine diet, and ES (30, 60 mg/kg) was co-administered for 4 weeks as a prophylactic intervention. Serum creatinine (SCr), blood urea nitrogen (BUN), and renal histopathology (HE, Masson, IHC) were evaluated to assess renal injury. Network pharmacology and transcriptomics were combined to screen the targets, and Western blot was used to verify the signaling pathways. Results: ES significantly reduced SCr and BUN levels in CKD mice and alleviated renal tubular dilation and inflammatory infiltration. ES decreased pro-inflammatory factors (IL-1β, IL-6, TNF-α) and MDA levels and enhanced SOD activity. Additionally, ES inhibited renal interstitial collagen deposition and reversed epithelial–mesenchymal transition (EMT) by upregulating E-cadherin and downregulating α-SMA levels. Mechanism studies confirmed that ES significantly inhibited the phosphorylation levels of p-EGFR, p-SRC, p-PI3K, p-AKT, and p-p65 in renal tissues. Conclusions: ES effectively inhibits inflammation, oxidative stress, and fibrosis by modulating the EGFR/SRC/PI3K/AKT/NF-κB signaling axis, thereby preventing the AKI-to-CKD transition in the adenine-induced renal injury model and alleviating the progression of chronic renal damage.