Moshen granule ameliorates membranous nephropathy by blocking intrarenal renin-angiotensin system signalling via the Wnt1/β-catenin pathway.

Background: Membranous nephropathy (MN) is one of the cardinal causes of nephrotic syndrome in adults, but an adequate treatment regimen is lacking.

Purpose: We assessed the effect of Moshen granule (MSG) on patients with MN and cationic bovine serum albumin (CBSA)-induced rats. We further identified the bioactive components of MSG and revealed the underlying molecular mechanism of its renoprotective effects.

Methods: We determined the effect of MSG on patients with MN and CBSA-induced rats and its components on podocyte injury in zymosan-activated serum (ZAS)-elicited podocytes and revealed their regulatory mechanism on the Wnt/β-catenin/renin-angiotensin system (RAS) signalling axis.

Results: MSG treatment improved renal function and reduced proteinuria in MN patients and significantly reduced proteinuria and preserved the protein expression of podocin, nephrin, podocalyxin and synaptopodin in CBSA-induced MN rats. Mechanistically, MSG treatment significantly inhibited the protein expression of angiotensinogen, angiotensin converting enzyme and angiotensin II type 1 receptor, which was accompanied by inhibition of the protein expression of Wnt1 and β-catenin and its downstream gene products, including Snail1, Twist, matrix metalloproteinase-7, plasminogen activator inhibitor-1 and fibroblast-specific protein 1, in CBSA-induced MN rats. We further identified 81 compounds, including astragaloside IV (AGS), calycosin, barleriside A and geniposidic acid, that preserve the podocyte-specific protein expression in ZAS-induced podocytes. Among these four compounds, AGS exhibited the strongest inhibitory effects on podocyte protein expression. AGS treatment significantly inhibited the protein expression of RAS components and Wnt1 and β-catenin and its downstream gene products in ZAS-induced podocytes. In contrast, the inhibitory effect of AGS on podocyte-specific proteins, β-catenin downstream gene products and RAS components was partially abolished in ZAS-induced podocytes treated with ICG-001 and β-catenin siRNA.

Conclusion: This study first demonstrates that AGS mitigates podocyte injury by inhibiting the activation of RAS signalling via the Wnt1/β-catenin pathway by both pharmacological and genetic methods. Therefore, AGS might be considered a new β-catenin inhibitor that inhibits the Wnt1/β-catenin pathway to retard MN in patients.