Study For Triptolide In Protection Against Lps-induced Acute Lung Injury In Rats

Objective To establish and evaluate the model of LPS-induced acute lung injury in rats.Methods 30 male SD rats weighting 200~250g were randomly divided into 2 groups: Control group (C, n=15) and Model group (M, n=15). C group was administered with 5ml/kg normal saline, M group was injected with 5mg/kg LPS (E. coli O111:B4 Sigma), both groups received the same volume of drugs. Arterial partial pressure of oxygen (PaO2), arterial partial pressure of carbon dioxide (PaCO2) and pH were recorded 1 hour before injection and 3, 6, 12 hours after injected. Rats were executed at 12 hour after injection and used for evaluate the pathological changes of lung. Tumor necrosis factor-α(TNF-α) were determined by enzyme linked immunosorbent assay (ELISA) in serum and bronchoalveolar lavage fluid (BALF). And the wet to dry weight ratio of right middle lobe of lung was calculated.Results The damage of pulmonary alveoli, edema of interstitial substance, inflammatory cell infiltrate, telangiectasis and hyperemia were happened in M group. Compared to C group, the pathological changes of M group were more serious in edema of interstitial substance, inflammatory cell infiltrate and telangiectasis (P < 0.05) . Furthermore, the PaO2 of M group reduced to 75.75±11.65mmHg at 3 hour after administrated and decreased more later. TNF-αlevel of M group increased markedly in serum and BALF. Similar changes in wet to dry weight ratio of right middle lobe of lung were observed. The results were statistically significant difference from C and M groups (P<0.05).Conclusion The model of ALI in rats can be established successfully by injection of LPS 5mg/kg.Objective To investigate the effect of triptolide on Toll-like receptor 4 (TLR4) expression and downstream signal transduction and explore the possible mechanism of triptolide on acute lung injury.Methods1. The protection of triptolide to LPS-induced ALI in rats.40 male SD rats weighting 200~250g were randomly divided into 4 groups: Normal group (N, n=5), Control group (C, n=5), LPS group (L, n=15), Triptolide group (TP, n=15). N group was not given any treatments, C group was intravenously administered with 5ml/kg normal saline and intraperitoneally injected with 7.5ml/kg 1%DMSO, L group was respectively given with 10mg/kg LPS and 7.5ml/kg 1%DMSO, TP group was respectively given with 10mg/kg LPS and 50μg /kg triptolide, all of groups had the same volume of injection. Arterial blood gases, the ratio of wet to dry weight, mortality, TNF-αlevel in serum and BALF and the pathological changes of lung were examined after injection of LPS or normal saline.2. The effect of triptolide on the expression of TLR4 and downstream signal transduction pathway.42 male SD rats weighting 200~250g were randomly divided into 6 groups: Normal group (N, n=5), Control group (C, n=5), LPS group (L, n=8), 25μg/kg triptolide group (TP1, n=8), 50μg/kg triptolide group (TP2, n=8) and 100μg/kg triptolide group (TP3, n=8). N group was not given any treatments; C group was intravenously administered with 5ml/kg normal saline and intraperitoneally injected with 7.5ml/kg 1%DMSO; L group was respectively given with 5mg/kg LPS and 7.5ml/kg 1%DMSO; TP1, TP2 and TP3 were intravenously administered with 5mg/kg LPS and respectively intraperitoneally injected with 25μg/kg, 50μg/kg or 100μg/kg triptolide. All of groups had the same volume of injection. TNF-αlevel in serum and BALF was measured by ELISA. The relative mRNA expression of TLR4 and NF-κB were measured by RT-PCR. The relative protein level of TLR4 was measured by western blot.Results1. Significant increase in PaO2 at 6, 12 and 24 hour after injection in TP group compared to L group. But it was less than N and C group at 3, 6, 12 and 24 hour after injection (P<0.05). TNF-αlevel in serum and BALF, the ratio of wet to dry weight and the mortality of 24 hours decreased markedly in TP group compared to L group. The pathological damage of lung in TP group was less than in L group. The results show statistically difference from TP and L group (P<0.05).2. The expression of TLR4, NF-κB mRNA and TLR4 protein level were represented downtrend with the dosage increase of triptolide. There were significant decrease in the expression of TLR4, NF-κB mRNA ,TLR4 protein and TNF-αlevel in TP2 and TP3 group compared to L group (P<0.05 ).Conclusion1. Rats can be protected from LPS-induced acute lung injury by triptolide.2. The expression of TLR4 and activation of NF-κB can be inhibited by triptolide. Furthermore, the secretion of inflammatory factor can be decreased by triptolide. Therefore the down regulation of TLR4 and its downstream signal transduction may be one of the effect of mechanisms of triptolide.3. The immunoloregulation of triptolide was dose-dependence.