Introduction:
This study aimed to discuss the use of hydroxysafflor yellow A (HSYA) to improve renal fibrosis induced by diabetes and its relative mechanisms, as well as to evaluate the level of renal histopathology and fibrosis in different rat groups.

Material and methods:
Sprague-Dawley (SD) rats (n = 27) were divided into the normal control (NC), diabetes mellitus (DM), and HSYA groups. The miRNA-140-5p mRNA, blood glucose (BG), 24-h urine protein (UP), total cholesterol (TC), triglyceride (TG), total anti-oxidant capacity (T-AOC), malondialdehyde (MDA), interleukin-6 (IL-6), and tumour necrosis factor-α (TNF-α) were measured in different groups. Moreover, the relative protein expression was measured via immunohistochemistry (IHC) assay. In the in vitro cell experiment, we discussed the effects of miRNA-140-5p on renal fibrosis induced by diabetes. Toll-like receptor 4 (TLR4), nuclear factor B (p65) (NF-κB(p65)), NOD-like receptor protein 3 (NLRP3), Notch2, and collagen IV (Col-IV) protein expression were evaluated using western blotting in the different cell groups. We evaluated the important protein expressions and NF-κB(p65) nuclear volume by cellular immunofluorescence. A correlation between miRNA-140-5p and TLR4 was found by dual-luciferase reporter assay.

Results:
In the in vivo study, HSYA improved diabetes-induced renal fibrosis. The severity of fibrosis significantly decreased after treatment with HSYA. In the HSYA group, the miRNA-140-5p mRNA, BG, 24-h UP, TC, TG, T-AOC, MDA, IL-6, and TNF-α significantly improved, as well as the TLR4, NF-κB(p65), NLRP3, Notch2, and Col-IV proteins. In the in vitro experiment, miRNA-140-5p was significantly decreased after treatment with HSYA in diabetes-induced renal fibrosis.

Conclusions:
HSYA improved diabetes-induced renal fibrosis by regulating miRNA-140-5p.