Mechanism of Zhenwu Tang modulating TLR4/NF-κB/HIF-1α loop through miR-451 to delay renal fibrosis in type 2 CRS

Background Type 2 cardiorenal syndrome (CRS) is a progressive renal insufficiency in patients with chronic heart failure, but its pathophysiology is still unclear. The Chinese medicine Zhenwu Tang plays an important role in the prevention and treatment of 2-CRS, however, its mechanism of action remains unknown. Purpose The aim of this study was to investigate whether the ameliorative effect of ZWT on 2-CRS renal fibrosis is related to the modulation of miR-451 expression and thus mediating the TLR4/NF-κB/HIF-1α loop. Study design and methods A type 2 CRS rat model was constructed using ligation of the left anterior descending branch of the coronary artery + 3/4 nephrectomy, and randomly divided into Control, Sham, Model, Captopril, ZWT-L, ZWT-M and ZWT-H groups.After 4 weeks of ZWT intervention, its effects on cardiac and renal functions of type 2 CRS rats were observed by hematuria and cardiac ultrasonography. Changes in kidney tissue morphology were observed by HE, Masson and PASM staining. The protein and mRNA expression of TLR4, NF-κB, HIF-1α and IκBα in kidney tissues were detected by immunohistochemistry and qPCR. Immunofluorescence was used to detect the protein expression of NF-κB and HIF-1α in renal tissues. Western blot and qPCR were used to detect the protein expression of MCP-1, ICAM-1, IL-1β, IL-6, TGF-β, α-SMA, FN, Smad2, Smad3, and E-cadherin in renal tissues. PCR was used to detect the protein expression of miR-451mRNA expression level in kidney tissues. Results In this study, we found that ZWT was able to reduce the expression of Scr, BUN, NT-proBNP, and 24-hour quantitative urine protein, elevate LVEF, FS, CO, and reduce the level of LVIDS in type 2 CRS rats, as well as attenuate renal interstitial fibrosis and improve tubular swelling. In addition, Zhenwu Tang up-regulated the expression of miR-451 in renal tissues and inhibited the expression of TLR4, NF-κB, and HIF-1α proteins and genes, which in turn inhibited the expression of inflammatory factors and fibrosis-related factors. Conclusion ZWT was able to up-regulate the expression of miR-451 in renal tissues, inhibit the TLR4/NF-κB/HIF-1α response loop, and then inhibit the expression of inflammatory factors and fibrosis-related factors, improve renal fibrosis, and delay the pathological process of type 2 CRS.