Renal tubular epithelial cell related partial epithelial-mesenchymal transition in AAⅠ induced renal fibrosis via Wnt7b/β-catenin signaling

Yi-fan Wang^1*Dan Zheng²Ying Zhang¹Xiao-fen Li¹Ming Xia¹Hai- Ming Tang¹Chun-Hua Huang¹Mao-juan Li¹Di-Dong Lou^1*

• ¹Guizhou University of Traditional Chinese Medicine, Guiyang, China
• ²Maternal and Child Health Care Hospital of Guiyang City, Guiyang, Guizhou Province, China

This study investigates the pathological progressions in kidneys affected by aristolochic acid nephropathy (AAN) and explores the molecular mechanisms underlying the fibrotic process, specifically focusing on the Wnt7b/β-catenin signaling pathway. Both mice and human kidney-2 (HK-2) cells were subjected to treatment with aristolochic acid Ⅰ (AAI). The levels of blood urea nitrogen (BUN), serum creatinine (Scr), and kidney injury molecule-1 (KIM-1), along with the pathological modifications of renal tubular epithelial cells (RTECs) and the degrees of fibrosis, were monitored in mice during the distinct acute and chronic phases of the disease. The expression levels of Wnt7b/β-catenin were evaluated via transcriptome data analysis and laboratory assays (including immunohistochemistry, western blotting, and immunoelectron microscopy) in acute AAN and in vitro cultured cells.Concurrently, in similar assays, we examined the expressions of several representative proteins. These included Aquaporin 1 (AQP1), which is associated with epithelial cells; Topoisomerase Ⅱα (TOP2A), which is related to cell proliferation; Vascular Cell Adhesion Molecule-1 (VCAM-1); and α-smooth muscle actin (α-SMA), which are associated with myofibroblasts in RTECs of mice with chronic AAN. The findings indicated that AAⅠ increased Scr, BUN, and KIM-1 levels by instigating necrotic shedding of RTECs in the acute stage and facilitated renal interstitial fibrosis in the chronic phase. The protein expression levels of the Wnt7b signaling pathway were elevated to boost the regeneration of damaged RTECs, and these regenerated epithelial cells expressed the mesenchymal proteins VCAM-1 and α-SMA. Our research helps explain how aristolochic acid nephropathy develops. We found that the Wnt7b/β-catenin signaling pathway plays a key role in connecting acute kidney tubule damage to the later stages of fibrosis. This gives us a better understanding of the continuous process of AAN's pathology.