摘要Objective: To investigate the significance of toll receptor-9 (TLR-9) expression in rats with acute lung injury (ALI) induced by thoracic trauma. Methods:Fifty healthy male SD rats were selected for the study, and 40 of them were randomly selected to establish the acute lung injury model induced by thoracic trauma, and 8 rats were randomly selected at 5, 24, 48 and 72 h after the impact, which were killed by cervical dislocation after arterial bleeding, and the lung tissue sections were made. Randomly select 8 rats from the remaining 10 rats as the control group, take blood and kill them to make lung tissue sections for reference. The lung dry/wet weight ratio (W/D) of the five groups were compared, and the levels of TLR-9 in bronchoalveolar lavage fluid (BALF) and serum, and the levels of TLR-9 mRNA, IL-6 mRNA, TLR-9 protein and IL-6 protein in lung tissue were detected. Results:There was no significant difference in W/D levels among the control group, experimental group 1 and experimental group 4 ( P＞0.05), while the W/D level of experimental group 3 was higher than that of the other four groups, and the W/D level of experimental group 2 was higher than that of the control group ( P＜0. 05). The levels of ILR-9 in serum and BALF of rats in experimental group 1, experimental group 2 and experimental group 4 had no significant difference ( P＞0.05), which were higher than those in control group and lower than those in experimental group 3 ( P＜0.05). The levels of TLR-9 mRNA, IL-6 mRNA, TLR-9 protein and IL-6 protein were the highest in the experimental group 3, and the lowest in the control group ( P＜0.05). The levels of TLR-9 mRNA and IL-6 mRNA in lung tissue of rats in experimental group 1, experimental group 2 and experimental group 4 had no significant difference ( P＞0.05). There was no significant difference in the levels of TLR-9 protein and IL-6 protein between experimental group 2 and experimental group 4 ( P＞0.05), which were higher than those in experimental group 1 (P＜0.05). Conclusion: The expression level of TLR-9 is significantly increased in rats after thoracic trauma, and the expression of TLR-9 can reflect the degree of lung injury in rats after trauma to a certain extent, which is inferred to be related to the inflammatory response after lung injury.