Astragalus Membranaceus And Salvia Miltiorrhiza Ameliorate Acute Lung Injury Based On The Toll-like Receptor 4/Nuclear Factor-kappa B Signaling Pathway

ObjectiveBased on the theory of Acute Lung Injury (ALI) and the relationship between ALI and toll-like receptor 4/Nuclear factor-kappa B (TLR-4/NF-?B) signaling pathway,we investigated the preventive and therapeutic effects and molecular mechanism of Astragalus membranaceus and Salvia miltiorrhiza (AM/SM) on LPS induced ALI rats by animal experiment. We explain the target and mechanism from the molecular biology level and provide theoretical basis for clinical application.Methods1. 20 male SD rats were randomly divided into normal control(NC) group and model group, ten in each group. NC group was instilled normal saline, while ALI model groups were established by intratracheal instillation of LPS. Observe their respiration, activity and so on after administration. Rats were put into death at each time space, then the arterial blood gas analysis, lung wet-to-dry (W/D)weight ratio and protein content in bronchoalveolar lavage fluid (BALF)were measured. The pathological changes of lung tissues were observed under light microscope.2. 40 male SD rats were randomly divided into five groups (NC group, model group,dexamethasone group, herbs treatment groupand and herbs prophylactico-therapeutic group), eight in each group. While NC group was instilled normal saline, other groups were established by intratracheal instillation of LPS. 3 days before and after making the model, the drug (4.725g/kg herbs or dexamethasone for 5mg/kg) or same amount of normal saline was given in each group by gavage, and observe their respiration, activity and so on. Rats were put into death after 2h of the last administration. Then the lung W/D weight ratio, the protein content in BALF, and the pathological changes of lung tissues were observed under light microscope.3. 30 male SD rats were randomly divided into NC group, model group and AM/SM herb group, ten in each group. ALI models were established by intratracheal instillation of LPS, while NC group was instilled normal saline. 3 days before and after making the model, the drug (4.725g/kg herbs) or same amount of normal saline was given in each group by gavage. Rats were put into death after 2h of the last administration. Then the concentrations of tumor necrosis factor(TNF- a ), interleukin 1?(IL-1?), interleukin 6(IL-6) in BALF tissue were measured by ELISA, and the the protein and mRNA expressions of TLR-4,interleukin-1 receptor-associated kinase-1 (IRAK-1) and NF-?B were measured by Immunohistochemistry and reverse transcriptase polymerase chain reaction respectively.Results1. Compared with NS group, LPS group exhibited a higher level for the PaC02,lung W/D weight ratio and protein content in BALF(P<0.01), a lower level for the Pa02; LPS group was characterized by destruction of alveolar structure,thickening of pulmonary septum,congestion and edema and a large number of inflammatory infiltrates in alveolar cavity, while lung structure in the NS group was complete without obvious pathological changes.2. Compared with normal control group, LPS groups exhibited a higher level for the lung W/D weight ratio, the protein content in BALF and the pathology score of lung tissue (P<0.01); compared with model control group, dexamethasone group and herbs group decreased the levels (P<0.01); for the lung W/D weight ratio and the pathology score of lung tissue, herbs prophylactico-therapeutic group was lower than herbs treatment group (P<0.01 or P<0.05), but there was no difference when compared with dexamethasone group(P>0.05); for the protein content in BALF, herbs prophylactico-therapeutic group was lower than herbs treatment group(P<0.01), but was higher than dexamethasone group(P<0.05).3. For TNF-a, IL-1?, IL-6 concentration in BALF, LPS group and herb groups increased the levels when compared with normal control group, while herb treatment decreased the levels when compared with the LPS group. For mRNA relative expression and protein of TLR-4, IRAK-1, NF-?B, LPS group and herb group upregulated the expression when compared with normal control group,while herb group downregulated the expression when compared the LPS group.Conclusion1. In our study, intratracheal instillation of LPS (5 mg/kg) method could successfully induce ALI model, and we can further study the preventive effect and its mechanism of traditional Chinese medicine on ALI based on it.2. Compatibility of Astragalus membranaceus and Salvia miltiorrhiza play a prophylactico-therapeutic role in ALI induced by lipopolysaccharide in rats,which improve the pathological changes of lung tissue, and early drug intervention helps to reduce inflammation injury.3. The protective and therapeutic effects of Astragalus membranaceus and Salvia miltiorrhiza on LPS-induced ALI in rats maybe due to its ability to modulate TLR4/ NF-?B signaling pathways.