Study On The Variation Of ACE2 Expression In LPS-induced ALI And The Role Of AT1-R Antagonist

ObjectiveTo observe the variants of ACE2 expression in injured lung tissue and cultured pulmonary microvascular endothelial cells on LPS induced acute lung injury, and the interferential action of angiotensin II type 1 receptor (AT1R) antagonist was examed to identify whether AT1R is involved in the changes of ACE2 expression. Meanwhile, to investigate the role of ACE2,AngⅡand AT1R inter-reaction in the pathogenesis of LPS-induced ALI.MethodsRat pulmonary microvascular endothelial cell (PMVEC)was isolated and cultured, PMVECs were stimulated with LPS 10-4,10-3,10-2and 10-1mg/ml at 24h time point, and then with LPS(10-1mg/ml) at 3h,6h,12hand 24h respectively; the gene and protein expression of ACE2 were assessed by semi-quantitative reverse transcriptase–polymerase chain reaction(RT-PCR) and western blot assays in vitro and in vivo respectively.Rats were injected with LPS (5mg/kg) through caudal vein to model acute lung injury in vivo. Rat lung tissue was isolated for pathological study with HE stain after stimulated 3h, 6h, 12h and 24h respectively. RT-PCR and Western blotting assay were taken to find the change of ACE2 mRNA and its corresponding protein in lung tissue. Results1. Rat PMEVC was successfully isolated in vitro.2. LPS could down regulate mRNA of ACE2 and its expression in the rat PMVEC in a concentration depending manner.3. LPS could down regulate the mRNA level of ACE2 and its expression in the rat PMVEC in a time depending manner, excepting at the point of 6h.4. Antagonist against AT1R could partially depress the down regulation of protein level of ACE2 in the rat PMVEC caused by LPS.5. The module of acute lung injury was successfully made by LPS injection.6. LPS could down regulate mRNA of ACE2 and its expression in rat lung tissue in a time depending manner.7. Antagonist against AT1R could partially depress the down regulation of ACE2 level in rat lung tissue caused by LPS.Conclusion1. LPS could down regulate mRNA of ACE2 and its expression in the PMVECs and lung tissue in a concentration and time depending manner ; excepting at the point of 6h .2. Antagonist against AT1R could partially depress the down regulation of the expression of ACE2 in the PMVECs and lung tissue by LPS.3. The interaction among ACE2, AngII and AT1R may pay an important role in the process of acute lung injury induced by LPS.