Objective To observe the effect of vitamin D on angiotensin converting enzyme 2 (ACE2) and vitamin D receptor (VDR) expression in Wister rat models of acute lung injury (ALI) induced by using lipopolysaccharide (LPS).Methods The rat models of ALI induced by LPS were established by intravenous injection of LPS via tail vein.Thirty Wistar rats were randomly (random number) divided into 6 groups:normal control group,LPS group,calcitriol (25 μg/kg) group,LPS + calcitriol 1 μg/kg group,LPS + calcitriol 5 μg/kg group and LPS + calcitriol 25 μg/kg group.The changes of general condition,lung pathology,lung wet/dry weight ratio and changes of VDR mRNA and ACE2 mRNA expressions and protein levels of VDR and ACE2 in rats were observed.Results The clinical manifestations (rapid shallow breathing;listlessness;the oral and nose hemorrhage) in LPS group were obvious,and the clinical manifestations and pathological changes of lung tissues in the LPS + calcitriol groups were significantly milder than those in LPS group.The expressions of VDR mRNA and ACE2 mRNA in LPS group was significantly lower than those in normal control group and calcitriol group (P ＜ 0.05).The expressions of VDR mRNA and ACE2 mRNA in LPS + calcitriol groups were significantly higher than those in LPS group (P ＜ 0.05),and lower than those in normal control group significantly (P ＜ 0.05).Meanwhile,among LPS + calcitriol groups,there was no significant difference in expression of VDR mRNA (P ＞ 0.05) and there was significant difference in ACE2 mRNA expression (P ＜ 0.05).Conclusions Calcitriol can increase the expressions of VDR mRNA and ACE2 mRNA and protein levels of VDR and ACE2 in rat models of LPS-induced ALI,thus suggesting the increased expressions of ACE2 mRNA and VDR mRNA playing a role in protection against the development of ALI.