Effect of Sedum sarmentosum BUNGE Extract on Aristolochic Acid-Induced Renal Tubular Epithelial Cell Injury

Aristolochic acid (AA) is known as a potent mutagen that induces significant cytotoxic and mutagenic effects on renal tubular epithelial cells. Clinically, the persistent injury of AA results in the infiltration of inflammatory cells, epithelial-to-mesenchymal transition (EMT), and renal tubulointerstitial fibrosis. There are no truly effective pharmaceuticals. In this study, we investigated the potential role of the extract of Sedum sarmentosum BUNGE (SSB), a traditional Chinese herbal medicine, on rat tubuloepithelial (NRK-52E) cells after AA injury in vitro. Evidence revealed that AA induced mitochondrial-pathway-mediated cellular apoptosis, accompanied by cell proliferation in a feedback mechanism. Treatment with SSB also induced cells to enter early apoptosis, but inhibited cell proliferation. In cultured NRK-52E cells, AA induced the imbalance of MMP-2/TIMP-2 and promoted EMT and ECM accumulation. SSB treatment significantly alleviated AA-induced NRK-52E cells fibrosis-like appearance, inhibited the induction of EMT, and deposition of ECM. SSB also decreased the activity of the NF-kappa B signaling pathway, resulting in down-regulated expression of NF-kappa B-controlled chemokines and pro-inflammatory cytokines, including MCP-1, MIF, and M-CSF, which may regulate the macrophage-mediated inflammatory reaction during renal fibrosis in vivo. Therefore, these findings suggest that SSB exerts protective effects against AA-induced tubular epithelial cells injury through suppressing the synthesis of inflammatory factors, EMT, and ECM production.