Effect of Baicalin on the Inflammatory Response of Lung Tissue in Severe Pneumonia Rats by Regulating the TGF-β1/Smad Signaling Pathway
Objective:To investigate the effect of baicalin(BC)on the inflammatory response of lung tissue and the transforming growth factor-β1(TGF-β1)/Smad signaling pathway in severe pneumonia(SP)rats.Methods:SD rats were randomly separated into a control group,a model group(SP group),low,me-dium,and high-dose baicalin groups(BC-L,BC-M,BC-H groups),and a high-dose baicalin+pathway activator group(BC-H+SRI-011381 group),with 18 rats in each group.Except for the control group,all other rats were used to construct an SP rat model.The lung coefficient(LI)and wet/dry weight ratio(W/D)of rats in each group were measured.ELISA was applied to detect the levels of inflammatory factors and severe pneumonia related biomarkers procalcitonin(PCT)and C-reactive protein(CRP)in alveolar lavage fluid.Wright's staining was applied to detect the number of neutrophils(NEU),eosinophils(EOS),and lympho-cytes(LYM)in the sediment of alveolar lavage fluid.HE staining was applied to observe the pathological morphology of lung tissue.Western blot was applied to detect the expression of TGF-β1/Smad signaling path-way related proteins.Results:Compared with control group,SP group showed damage in lung tissue struc-ture,with some areas of alveolar edema showing bleeding,thickening of alveolar walls and lung interstitium,and infiltration of a large number of inflammatory cells,the levels of LI,W/D,TNF-α,IL-1β,IL-6,PCT,CRP,the numbers of NEU,EOS,and LYM,and the expression of TGF-β1,p-Smad2/Smad2,and p-Smad3/Smad3 were elevated(P<0.05).Compared with SP group,BC-L,BC-M,and BC-H groups showed improvement in lung tissue structure damage,with relatively normal alveolar morphology,reduced ede-ma,and reduced infiltration of inflammatory cells,the levels of LI,W/D,TNF-α,IL-1β,IL-6,PCT,CRP,the numbers of NEU,EOS,and LYM,and the expression of TGF-β1,p-Smad2/Smad2,and p-Smad3/Smad3 were reduced(P<0.05).Compared with BC-H group,BC-H+SRI-011381 group showed more severe damage to lung tissue structure and alveolar edema,with increased infiltration of inflammatory cells,the levels of LI,W/D,TNF-α,IL-1β,IL-6,PCT,CRP,the numbers of NEU,EOS,and LYM,and the expression of TGF-β1,p-Smad2/Smad2,and p-Smad3/Smad3 were elevated(P<0.05).Conclu-sion:Baicalin can improve lung tissue inflammation in SP rats,and its mechanism of action is related to the inhibition of TGF-β1/Smad pathway.
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