Sini decoction alleviates E. coli induced acute lung injury in mice via equilibrating ACE-AngII-AT1R and ACE2-Ang-(1-7)-Mas axis

Aims: Acute respiratory distress syndrome (ARDS), one of the serious form of acute lung injury (ALI), is the primary cause of death in patients with ALI. Sini decoction (SND) is a widely used Traditional Chinese Medicine (TCM). However, the application of SND in ALI is rarely reported. Previous studies have found that renin-angiotensin-aldosterone system (RAAS) played vital and bidirectional roles in ALI. Therefore, the aim of the present study was to investigate protective effect of SND on ALI model induced by E. coli, as well as to further explore relations between RAAS and SND. Materials and methods: The ALI model was evaluated by morphological observations and biochemical assays. The expression levels of angiotensin converting enzyme (ACE), Angiotensin II type 1 receptor (AT1R) and angiotensin converting enzyme 2 (ACE2) were examined by Western blotting. The expression levels of angiotensinII (AngII) and angiotensin-(1-7) (Ang-(1-7)) were measured through ELISA. MasR, IL-6, IL-1 beta and TNF alpha were all measured using qRT-PCR. Key findings: SND significantly ameliorated E. coli-induced ALI, including reducing inflammatory factors in lung tissue and the activity of MPO in serum. Furthermore, SND could obviously decrease the expression of ACE, AngII and AT1R, which were induced by E. coli. On the other hand, SND could markedly activate ACE2-Ang-(1-7)-Mas pathway. Significance: In this paper, we demonstrated that SND alleviates E. coli induced acute lung injury in mice via equilibrating ACE-AngII-AT1R and ACE2-Ang-(1-7)-Mas axis.