Effect of Danggui Buxuetang on Podocyte Pyroptosis in Diabetic Kidney Disease Rats： An Exploration Based on TXNIP/NLRP3/GSDMD Signaling Pathway / 中国实验方剂学杂志

ABSTRACT

ObjectiveTo observe the effect of Danggui Buxuetang on podocyte pyroptosis in diabetic kidney disease （DKD） rats and to explore the possible mechanism of its prevention and treatment of DKD and podocyte pyroptosis. MethodEight of the 50 male SD rats were randomly classified into a normal group， and the remaining 42 were fed a high-glucose and high-fat diet for six weeks and then intraperitoneally injected with 35 mg·kg-1 streptozotocin （STZ） for inducing type 2 diabetes. After successful modeling， they were randomized into the model group， low- （0.72 g·kg-1） and high-dose （1.44 g·kg-1） Danggui Buxuetang group， and irbesartan （0.017 g·kg-1） group and gavaged with the corresponding drugs， while those in the normal group and model group with an equal volume of normal saline， once per day， for 20 weeks. During the medication， the fasting blood glucose （FBG） and 24 h urine protein （24 h-UTP） were measured regularly. After administration， the pathological changes in renal tissues were observed by periodic acid-silver metheramine （PASM） staining， followed by the observation of ultrastructural changes in podocytes under the transmission electron microscope （TEM）. Serum levels of interleukin-1β （IL-1β） and interleukin-18 （IL-18） were determined by enzyme-linked immunosorbent assay （ELISA）. The DNA damage in renal tissue cells of rats was detected by in situ nick end-labeling （TUNEL） assay. The protein expression levels of thioredoxin interacting protein （TXNIP）， cysteine-dependent aspartate-directed protease-1 （Caspase-1）， and gasdermin D （GSDMD） in renal tissues of rats were detected by immunohistochemistry （IHC）， the expression levels of nucleotide binding domain like receptor protein 3 （NLRP3） and Wilms tumor protein-1 （WT-1） in podocytes by immunofluorescent （IF） staining， and the expression levels of TXNIP/NLRP3/Caspase-1/GSDMD pathway proteins and Synaptopodin in renal podocytes by Western blot. ResultCompared with the normal group， the model group exhibited increased FBG and 24 h UTP， glomerular hypertrophy， mesangial hyperplasia， increased extracellular matrix， thickened basement membrane， K-W nodules， vacuolar degeneration in renal tubular epithelial cells， foot process fusion or loss， elevated serum IL-1β and IL-18 levels and TUNEL-positive cells in renal tissue， enhanced NLRP3 but diminished WT-1 expression in podocytes， down-regulated Synaptopodin protein expression， and up-regulated TXNIP/NLRP3/Caspase-1/GSDMD protein expression （P<0.01）. Compared with the model group， Danggui Buxuetang high-dose group remarkably lowered FBG， 24-h UTP， and TUNEL-positive cells in renal tissue， improved renal histopathology and podocyte injury and loss， down-regulated NLRP3 expression in podocytes and TXNIP/NLRP3/Caspase-1/GSDMD protein expression levels， and up-regulated WT-1 expression in podocytes and Synaptopodin protein expression （P<0.05， P<0.01）. ConclusionDanggui Buxuetang inhibits podocyte pyroptosis to reduce proteinuria and delays the development of DKD possibly by regulating the TXNIP/NLRP3/GSDMD signaling pathway.