ABSTRACT
ObjectiveTo investigate the intervention effect of Buzhong Yiqitang （BZYQT） on pulmonary inflammation in mice induced by chronic intermittent hypoxia （CIH） and preliminarily elucidate its mechanism. MethodForty healthy male C57BL/6 mice aged 6-8 weeks were randomly divided into the following groups： normoxia group， model group （exposed to CIH）， and low-， medium-， and high-dose BZYQT groups. The normoxia group was exposed to a normoxic environment， while the model group and the low-， medium-， and high-dose BZYQT groups were exposed to intermittent hypoxia. In the BZYQT groups， the BZYQT （8.1， 16.2， 32.4 g·kg-1·d-1） was administered orally 30 min before placing the mice in the hypoxic chamber， while the model group and the normoxia group received an equivalent volume of normal saline. After five weeks of modeling， pulmonary function of the mice was measured using an EMKA animal lung function analyzer， and lung tissue samples were collected after the pulmonary function tests. Hematoxylin-eosin （HE） staining was performed to observe the histopathological changes in the lung tissue of each group. Enzyme-linked immunosorbent assay （ELISA） was used to measure the levels of interleukin-6 （IL-6）， interleukin-8 （IL-8）， tumor necrosis factor-α （TNF-α） in the serum， as well as angiotensin Ⅱ （Ang Ⅱ） and angiotensin-（1-7） ［Ang（1-7）］ in lung tissue. Western blot and immunohistochemistry were used to detect the protein expression of IL-6， IL-8， TNF-α， angiotensin-converting enzyme 2 （ACE2）， and mitochondrial assembly receptor （Mas）. ResultCompared with the normoxia group， the model group showed significant abnormalities in lung function （P<0.05， P<0.01）， lung tissue changes， such as thickening of alveolar walls and inflammatory cell infiltration， increased levels of IL-6， IL-8， TNF-α in the serum and Ang Ⅱ in lung tissue （P<0.01）， decreased level of Ang（1-7） （P<0.01）， increased protein expression of IL-6， IL-8， and TNF-α， and decreased protein expression of ACE2 and Mas （P<0.05， P<0.01）. Compared with the model group， the BZYQT groups showed improvement in lung function （P<0.05， P<0.01）， and HE staining of lung tissue showed approximately normal alveolar wall thickness and reduced inflammatory cell infiltration. Immunohistochemistry and Western blot analysis showed a significant decrease in the expression of inflammatory-related proteins （P<0.05， P<0.01）， and a significant increase in ACE2 and Mas protein expression （P<0.05， P<0.01）. ConclusionBZYQT can improve lung injury in mice exposed to CIH by regulating the ACE2-Ang（1-7）-Mas axis to inhibit inflammatory responses.