[Protective effects of Juhongtai standard decoction against acute lung injury via TLR4/MAPK/NF-κB signaling pathway].

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.