Mechanism of Huanglian Wendantang in Improving IR-HepG2 Based on NLRP3/Caspase-1 Signaling Pathway / 中国实验方剂学杂志

ABSTRACT

ObjectiveTo explore the effect of the serum containing Huanglian Wendantang on pyroptosis in vitro model of insulin resistance and its mechanism. MethodSD rats were randomly divided into two groups， namely Huanglian Wendantang-containing serum group and blank serum group， and given 7.8 g·kg-1·d-1 Huanglian Wendantang and equal volume of normal saline by intragastric administration according to body surface area. Blank serum and medicated serum with different concentration were extracted and prepared. HepG2 cells were treated with sodium palmitate to construct the model of insulin resistance （IR）， and they were randomly divided into control group， model group， metformin hydrochloride group， blank serum group， and Huanglian Wendantang-containing serum high-， medium-， and low-dose groups. After 24 h of cultivation， the cells of each group were treated with insulin for 15 min at concentration of 1×10-7 mol·L-1， and the cell supernatant was collected. The glucose oxidase （GOD-POD） kit was used to determine the glucose content of each group， and calculate the glucose consumption and inhibition rate. The methyl thiazolyl tetrazolium （MTT） assay was used to detect the cell proliferation， thus screening out the optimal dose of serum containing Huanglian Wendantang. HepG2 cells were randomly divided into control group， model group， and Huanglian Wendantang-containing serum group. The levels of interleukin-1β （IL-1β） and interleukin-18 （IL-18） in each group were determined by enzyme-linked immunosorbent assay （ELISA）， and the mRNA and protein expression levels of NOD like receptor protein 3 （NLRP3） in each group were determined by real-time fluorescence quantitative polymerase chain reaction （Real-time PCR） and Western blot. In terms of the mechanism， HepG2 cells were randomly divided into control group， empty vector group， NLRP3 overexpression group， empty vector + IR group， empty vector + IR + Huanglian Wendantang-containing serum group， NLRP3 overexpression + IR group， and NLRP3 overexpression + IR + Huanglian Wendantang-contain serum group. GOD-POD method was used to measure the glucose content of each group cells， and calculate the glucose consumption. ELISA was used to determine the release of IL-1β and IL-18 in each group. Real-time PCR and Western blot assay were used to determine the mRNA and protein expressions of cysteinyl aspartate specific proteinase-1 （Caspase-1）， gasdermin D （GSDMD）， and NLRP3. Immunofluorescence assay was used to detect NLRP3， GSDMD， and Caspase -1 expressions. ResultAs compared with the control group， the glucose consumption in the model group was significantly decreased （P<0.01）. As compared with the model group， the increase of the glucose consumption of IR-HepG2 cells was the most significant in the Huanglian Wendantang-containing serum high-dose group （P< 0.01）. As compared with the control group， the IL-1β and IL-18 release levels and the mRNA and protein expressions of NLRP3 in IR-HepG2 cells were significantly increased （P<0.05， P<0.01）. Huanglian Wendantang effectively reduced IR-HepG2 cell supernatant IL-1β， IL-18， and NLRP3 mRNA and protein expressions as compared with the model group （P<0.05， P<0.01）. Overexpression of NLRP3 significantly reduced the cell glucose consumption as compared with the control group and the empty vector group （P<0.01）， and significantly up-regulated the IL-1β and IL-18 levels and the mRNA and protein levels of NLRP3， Caspase-1， and GSDMD as compared with the empty vector + IR group （P<0.05， P<0.01）. Huanglian Wendantang-containing serum effectively reversed the above indicators as compared with the NLRP3 + IR group （P<0.05， P<0.01）. ConclusionHigh fat-induced insulin sensitivity of IR-HepG2 cells is closely related to inflammation and NLRP3 expression. Huanglian Wendantang-containing serum improves IR-HepG2 cell pyroptosis through the targeted inhibition of NLRP3/Caspase-1 signaling pathway， which provides new therapeutic targets for the prevention and treatment of IR and type 2 diabetes mellitus （T2DM）.