Urotensin II enhances transforming growth factor‑β1 expression and secretion in the kidney during aristolochic acid nephropathy.

Aristolochic acid is a component of many types of Chinese medicine, which are commonly used to treat almost all human diseases. However, aristolochic acid may cause nephropathy. Urotensin II (UII) and transforming growth factor (TGF)‑β1 are important signaling factors, which are expressed at elevated levels during the development of nephropathy. However, the association between UII and TGF‑β1 expression remains unclear. In the current study, the regulatory association between UII and TGF‑β1 expression was investigated using a rat aristolochic acid nephropathy model and the NRK‑52E cell line. The expression levels of UII and TGF‑β1 were identified to be constantly increased in the rat aristolochic acid nephropathy model, even 10 days after administration of Aristolochiae manshuriensis decoction was terminated. Notably, increases in the TGF‑β1 expression levels occurred later than those of UII. Furthermore, UII enhanced TGF‑β1 expression in, and secretion from, NRK‑52E cells. These data indicate that UII and TGF‑β1 are important in the development of aristolochic acid nephropathy, and UII enhances TGF‑β1 expression levels and secretion during aristolochic acid nephropathy. However, the underlying mechanisms for the precise roles of UII and TGF‑β1 as well as the method by which UII regulates the expression TGF‑β1 in aristolochic acid nephropathy remain to be elucidated in future studies.