基于TLR4/MAPK/NF-κB信号通路探讨橘红胎标准汤剂对急性肺损伤的保护作用OA

This study aimed to investigate the protective effect and mechanism of Juhongtai standard decoction(JSD)against lipopolysaccharide(LPS)-induced acute lung injury(ALI).In vivo,an ALI model was established using SD rats by intraperitoneal injection of LPS(5 mg·kg-1).The animals were randomly divided into six groups:control group,model group,dexamethasone(DEX,0.315 mg·kg-1)group,and low-,medium-,and high-dose JSD groups(0.787 5,1.575,and 3.15 g·kg-1,respectively).Wet/dry weight ratio(W/D),myeloperoxidase(MPO)activity,superoxide dismutase(SOD)activity in lung tissues,and nitric oxide(NO)levels in serum were measured.Pathological changes in lung tissue were observed by hematoxylin-eosin(HE)staining,and the percentage of alveolar area(PAA)was scored.Enzyme-linked immunosorbent assay(ELISA)and real-time quantitative polymerase chain reaction(RT-qPCR)were used to detect the content and mRNA expression of tumor necrosis factor(TNF)-α and interleukin(IL)-1β in serum and lung tissues.Immunohistochemistry and Western blot were employed to analyze the protein expression of Toll-like receptor 4(TLR4)and matrix metalloproteinase 9(MMP9),as well as the phosphorylation levels of inhibitor of nuclear factor-κB(IκB),p65,p38,and extracellular signal-regulated kinase(ERK).In vitro,A549 cells were stimulated with LPS(20 μg·mL-1)to establish an inflammation model and treated with JSD-containing serum.Cell viability was assessed by MTT assay.The mRNA expression of TNF-α,IL-1β,IL-6,IL-18,TLR4,myeloid differentiation factor 88(MyD88),MMP9,CXC chemokine ligand 2(CXCL2),and IL-10 was detected by RT-qPCR.Western blot was used to evaluate the phosphorylation of IκB,p65,p38,and ERK.The results showed that JSD significantly reduced the lung W/D ratio and alleviated pulmonary edema.It inhibited MPO activity and NO levels and enhanced SOD activity,which indicated the mitigation of oxidative stress.HE staining showed that it significantly ameliorated LPS-induced pathological changes,including alveolar structural destruction and inflammatory cell infiltration,and increased the PAA score.ELISA and RT-qPCR indicated that JSD decreased the levels and mRNA expression of pro-inflammatory cytokines such as TNF-α and IL-1β.Immunohistochemistry and Western blot revealed that JSD suppressed the protein expression of TLR4 and MMP9 and downregulated the phosphorylation of IκB,p65,p38 and ERK.In vitro,JSD-containing serum had no significant effect on cell viability but significantly reduced the mRNA expression of inflammatory factors(TNF-α,IL-1β,IL-6,IL-18,TLR4,MyD88,MMP9,and CXCL2)and increased the expression of the anti-inflammatory factor(IL-10).It also downregulated the phosphorylation of IκB,p65,p38 and ERK.In conclusion,JSD alleviates LPS-induced ALI by regulating the TLR4/MAPK/NF-κB signaling pathway and thereby suppressing inflammatory response and oxidative stress.