CHEN Liyuan, CHE Jiaozi, ZHU Cuimin
OBJECTIVE To investigate the effect of verbascoside (AC) on lung injury and inositol requiring enzyme 1α/thioredoxin-interacting protein/nucleotide binding oligomerization domain-like receptor protein 3 (IRE1α/TXNIP/NLRP3) signaling pathway in Streptococcus pneumoniae (SP) pneumonia rats. METHODS SP pneumonia model rats were constructed, and successfully modeled rats were randomly assigned into Model group, low and high dose verbascoside groups (AC-L, AC-H groups), high dose verbascoside+empty vector group (AC-H+pAdEEasyTM group), and high dose verbascoside+IRE1α overexpression adenovirus vector group (AC-H+Ad-IRE1α group), with 18 rats in each group. Another 18 healthy normal rats were as the Control group. The oxygenation index of rats in each group was measured. Enzyme-linked immunosorbent assay (ELISA) was used to detect the levels of inflammatory factors in bronchoalveolar lavage fluid. The wet/dry ratio (W/D) and oxidative stress level of lung tissue of rats in each group were detected. Hematoxyl-eosin (HE) staining was used to observe the pathological condition of lung tissue. Tdt mediated dutp nick end labeling (TUNEL) staining was used to detect apoptosis in lung tissue cells. Western blot was used to detect the expression of proteins related to the IRE1α/TXNIP/NLRP3 signaling pathway. RESULTS The lung tissue injury in the Model group was more significant than that in the Control group, with swollen and disordered alveolar epithelial cells, dilated alveolar wall capillaries, thickened alveolar septa, and significant infiltration of inflammatory cells, the PaCO2, levels of TNFα, IL-1β, IL-6, W/D, MDA, apoptosis rate, and the expression of Bax, p-IRE1α/IRE1α, TXNIP, and NLRP3 were higher, and the PaO2, OI, level of SOD, and the expression of Bcl-2 were lower (P<0.05). The lung tissue morphology of the AC-L and AC-H groups improved compared with the Model group, with slight thickening of the alveolar septa and infiltration of inflammatory cells, the PaCO2, levels of TNFα, IL-1β, IL-6, W/D, MDA, apoptosis rate, and the expression of Bax, p-IRE1α/IRE1α, TXNIP, and NLRP3 were lower, and the PaO2, OI, level of SOD, and the expression of Bcl-2 were higher (P<0.05). The PaCO2, levels of TNFα, IL-1β, IL-6, W/D, MDA, apoptosis rate, and the expression of Bax, p-IRE1α/IRE1α, TXNIP, and NLRP3 in the AC-H+Ad-IRE1α group were higher than those in AC-H+pAdEasyTM group, and the PaO2, OI, level of SOD, and the expression of Bcl-2 were lower (P<0.05). CONCLUSION Verbascoside can improve lung injury in SP pneumonia rats, and its related to the inhibition of the IRE1α/TXNIP/NLRP3 signaling pathway.