Total Flavonoids of Peony Flower Regulate NLRP3 Inflammasome and Expression of Inflammatory Cytokines in Gouty Nephropathy Rats / 中国实验方剂学杂志

ABSTRACT

ObjectiveTo explore the possible mechanism of total flavonoids of peony flower （TFPF） in protecting rats from gouty nephropathy and provide data support for the pharmaceutical research on the treatment of gouty nephropathy. MethodGouty nephropathy rat model was established by adenine combined with ethambutol. Rats were randomly assigned into blank control group， model group， allopurinol （42 mg·kg-1） group， Tongfengshu tablets （600 mg·kg-1， positive control） group， and TFPF （260， 130， and 65 mg·kg-1） groups. Enzyme-linked immunosorbent assay （ELISA） was employed to measure the levels of tumor necrosis factor-α （TNF-α）， monocyte chemoattractant protein-1 （MCP-1）， interleukin-1β （IL-1β）， and interleukin-18 （IL-18） in rat serum and those of transforming growth factor-β1 （TGF-β1） and IL-1β in renal homogenate. Hematoxylin-eosin（HE） staining was carried out for observation of the morphological changes of renal cells. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling （TUNEL） was conducted for observation of the DNA damage in renal cells. The expression of NOD-like receptor protein 3 （NLRP3）， cysteine aspartic acid protease（Caspase）-1 and IL-1β were observed by immunohistochemistry. The expression levels of NLRP3， Caspase-1 and nuclear transcription factor -κB （NF-κB） in renal tissues were detected by Western blot. ResultCompared with blank group， the contents of TNF-α， MCP-1， IL-1β， IL-18， and TGF-β1 in serum of model group were significantly increased （P<0.01）， and the expressions of NLRP3， Caspase-1， NF-κB and IL-1β in kidney of model group were significantly increased （P<0.01）. The renal tissue cells showed cytoplasmic swelling， cell membrane rupture， and the number of nuclear pyknotic fracture increased. The positive rate of TUNEL staining was significantly increased in model group （P<0.01）， and the contents of IL-1β and TGF-β1 in renal tissue homogenate were significantly increased （P<0.01）. Compared with model group， the contents of inflammatory factors TNF-α， IL-1β and IL-18 in serum of rats in TFPF high- and medium-dose groups could be decreased to different degrees （P<0.05， P<0.01）， while the content of MCP-1 in TFPF high-dose group was significantly decreased （P<0.01）. The content of TGF-β1 in renal tissue homogenate in TFPF high- and medium-dose groups was significantly decreased （P<0.05， P<0.01）， and the content of IL-1β in renal tissue homogenate in TFPF medium-dose group was significantly decreased （P<0.01）. HE staining showed that each dose group of TFPF could improve the status of renal tubular epithelial cells， reduce cytoplasmic swelling and the number of nuclear pyknosis to varying degrees. The positive rate of TUNEL staining was decreased （P<0.01） and DNA damage was decreased. The expression of NLRP3， Caspase-1， IL-1β and NF-κB protein in renal tissue cells was inhibited （P<0.05， P<0.01）. ConclusionTFPF protects rats from gouty nephropathy by inhibiting the secretion of inflammatory cytokines. Specifically， it may inhibit the activation of NF-κB and NLRP3/Caspase-1 pathways to reduce the expression， maturation， and release of inflammatory cytokines such as IL-1β and IL-18 and further inhibit pyroptosis， thereby reversing the inflammatory injury of kidney in gouty nephropathy.