Diabetic nephropathy (DN) is the major cause of end-stage renal disease in diabetic patients. Zicao, a well-known Chinese traditional medicine, has attracted much attention due to its beneficial effects in various medical fields. In this study, we attempted to investigate the effects and mechanisms of action of acetylshikonin, the main ingredient of Zicao, on renal dysfunction in DN. Our results showed that administration with acetylshikonin not only decreased blood urea nitrogen, urine creatinine and the mean kidney-to-body weight ratio in streptozotocin-induced diabetic mice, but also restored the loss of body weight, whereas the blood glucose was not changed. Masson’s trichrome staining showed that acetylshikonin treatment resulted in a marked decrease in kidney fibrosis from diabetic mice. The increased expression of fibrosis proteins, such as plasminogen activator inhibitor type 1 (PAI-1), connective tissue growth factor, and collagen III and IV, were reduced after acetylshikonin administration. In addition, the expressions of interleukin-1β, interleukin-6, monocyte chemoattractant protein-1, intercellular adhesion molecule 1 and infiltration of macrophages in kidney tissues were decreased in acetylshikonin-treated diabetic mice. Acetylshikonin led to a reduction of transforming growth factor-β1 (TGF-β1) expression and Smad-2/3 phosphorylation, as accompanied by increased Smad7 expression. Furthermore, in vitro treatment with acetylshikonin markedly attenuated TGF-β1-induced the PAI-1, collagen III and IV, and Smad-2/3 phosphorylation in HK2 immortalized human proximal tubule epithelial cells. Acetylshikonin also prevented epithelial-to-mesenchymal transition induced by TGF-β1. Collectively, our study provides evidences that acetylshikonin attenuates renal fibrosis though inhibiting TGF-β1/Smad signaling pathway, suggesting that acetylshikonin may be a novel therapeutic agent for the treatment of DN.
Deckert T, Poulsen JE, Larsen M. Prognosis of diabetics with diabetes onset before the age of thirty-one. I. Survival, causes of death, and complications. Diabetologia. 1978;14(6):363–70.CrossRefPubMedGoogle Scholar
Liu Y. Epithelial to mesenchymal transition in renal fibrogenesis: pathologic significance, molecular mechanism, and therapeutic intervention. J Am Soc Nephrol. 2004;15(1):1–12.CrossRefPubMedGoogle Scholar
Wang Z, Han Z, Tao J, Wang J, Liu X, Zhou W, Xu Z, Zhao C, Wang Z, Tan R, Gu M. Role of endothelial-to-mesenchymal transition induced by TGF-beta1 in transplant kidney interstitial fibrosis. J Cell Mol Med. 2017;. https://doi.org/10.1111/jcmm.13157.Google Scholar
Sonnylal S, Shi-Wen X, Leoni P, Naff K, Van Pelt CS, Nakamura H, Leask A, Abraham D, Bou-Gharios G, de Crombrugghe B. Selective expression of connective tissue growth factor in fibroblasts in vivo promotes systemic tissue fibrosis. Arthritis Rheum. 2010;62(5):1523–32. https://doi.org/10.1002/art.27382.CrossRefPubMedGoogle Scholar
Kavsak P, Rasmussen RK, Causing CG, Bonni S, Zhu H, Thomsen GH, Wrana JL. Smad7 binds to Smurf2 to form an E3 ubiquitin ligase that targets the TGF beta receptor for degradation. Mol Cell. 2000;6(6):1365–75.CrossRefPubMedGoogle Scholar
Hong SW, Isono M, Chen S, Iglesias-De La Cruz MC, Han DC, Ziyadeh FN. Increased glomerular and tubular expression of transforming growth factor-beta1, its type II receptor, and activation of the Smad signaling pathway in the db/db mouse. Am J Pathol. 2001;158(5):1653–63.CrossRefPubMedGoogle Scholar