Study For Triptolide Regulated The Expression Of ATP-binding Cassette Transporter A1in Acute Lung Injury Of Rats

Part Ⅰ. Establishment of animal model of LPS-inducedacute lung injury (ALI) on ratsPurpose This study was supposed to assess the reliability of LPS-induced acutelung injury (ALI) on rat.Methods Thirty male SD rats, with body weight ranging200~250g, wererandomized into two groups, with fifteen in each. The rats were intravenously administered5mg/kg LPS (Model group) or the equivalent amount of normal saline (Control group)through tail vein. Arterial blood was repeatedly sampled for blood-gas analysis at1hrbefore and3,6,12hr after injection. Immediately after last blood sampling, rats wereexecuted by decapitation. The lower lobe of right lung was harvested for paraffin slice, HEstaining, and histopathological examination under light microscope. And the middle lobeof right lung was saved for calculating ratio of wet to dry (W/D).Results As for blood-gas analysis, PaO2in Model group showed statisticallysignificant lower than that in Control group at3,6and12hr (P<0.05). And PaO2at12hrin Model group decreased by46.01%of baseline. Histopathological examination of lung,Gross: the lung in Control group displayed normal size, pink, glazed surface, fine section,with no exudation or congestion. While the lung in Model group appeared hypertrophy,wine-colored, subcapsularlly scattered bleeding spots, loose texture, with yellow or reddishextravasate. LM: the lung in Control group displayed intact structure, clear alveoli with fullcavity, smooth wall, and even space, no exudation or leucocyte in alveoli, and onlyinfrequent leucocyte at alveolus intervals. While the lung in Model group appearedmassive infiltration of inflammatory cells, conpicusous dilation and congestion of capillary,incomplete alveoli with damaged wall and massive erythrocyte, neutrophil, macrophage,extravasate, and even microthrombosis in between, augment of alveolus distance, andsome alveolus collapse. In all, the lower lobe of right lung in Model group exhibited statistically significant injury at aspects of capillary congestion, neutrophil infiltration, andincreased alveolus distance, as compared to Control group (P<0.05). The W/D ratio ofmiddle lobe of right lung in Model group denoted statistically significant greater than thatin Control group (P <0.05).Conclusion Based on histopathological changes and PaO2plummeting in Modelgroup, LPS5mg/kg i.v. can successfully build ALI model on rats.Part Ⅱ. Study for triptolide regulated the expression ofATP-binding cassette transporter A1in acute lunginjury of ratsPurpose This investigation was to explore influence of triptolide on ABCA1geneexpression and protein production on rat with LPS-induced acute lung injury.Methods Thirty male SD rats, with body weight ranging200~250g, wererandomized into six groups, with five in each. The rats were treated with nothing (GroupN), normal saline i.v.+1%DMSO i.p.(Group C), LPS5mg/kg i.v.+1%DMSO i.p.(Group L), LPS5mg/kg i.v.+triptolide25μg/kg i.p.(Group TP1), LPS5mg/kg i.v.+triptolide50μg/kg i.p.(Group TP2), and LPS5mg/kg i.v.+triptolide100μg/kg i.p.(Group TP3). Arterial blood was repeatedly sampled for blood-gas analysis at1hr beforeand3,6,12hr after injection. The lower lobe of right lung was harvested forhistopathological examination and evaluated by criteria of modified IDAD (improveddiffuse alveolar damage). And the middle lobe of right lung was saved for calculating ratioof Wet to Dry (W/D). The rest of lung tissue was used for measurement of ABCA1mRNAand protein by RT-PCR and Western blotting correspondingly. And plasma andbronchoaleolar lavage fluid (BALF) were aslo collected for measurement of TNF-α byELISA.Results1. Histopathological examination, IDAD score and W/D value: Group Nand C displayed both normal lung structure, and no statistically significant difference inIDAD score and W/D value (P<0.05). Both Group L and TP1exhibited increased alveolusdistance, obvious alveolus collapse and extravasate, and their IDAD score and W/D valuewere both significantly higher than that of Group N and C (P <0.05), and there was nosignificant difference between Group L and TP1(P>0.05). Group TP2displayed intactstructure of alveoli, however, interstitial edema, dilation and congestion of capillary,and infiltration of inflammatory cells, its IDAD score was significantly higher than Group Nand C, and significantly higher than Group L(P<0.05). Group TP3displayed increasedalveolus distance, slight alveolus collapse, interstitial edema, dilation and congestion ofcapillary,and infiltration of inflammatory cells, its IDAD score and W/D value wassignificantly lower than Group L(P<0.05), but no statistically significant difference ascompared to Group TP2(P>0.05).2. Blood-gas analysis: PaO2at3,6hr in Group L and TP1was statisticallysignificant lower than that in Group N and C (P<0.05). PaO2at3,6,12hr in Group TP2and TP3was statistically significant lower than that in Group N and C (P<0.05), and wasstatistically significant higher than that in Group L and TP1(P<0.05).3. ABCA1mRNA and protein: Group TP2and TP3were statistically significanthigher than Group L (P<0.05). However, there is no statistically significant differencebetween Group TP2and TP3(P>0.05).4. TNF-α in plasma and BALF at12hr: Group L and TP1were statisticallysignificant higher than Group N and C (P<0.05). Group TP2and TP3were statisticallysignificant lower than Group N and C (P<0.05). And TP3was also significantly lower thanthat in Group N and C (P<0.05).Conclusions1. Expression of ABCA1mRNA and protein decreases on rats with LPS-inducedacute lung injury.2. Triptolide protects the lungs of rats with LPS-induced acute lung injury bydecreasing inflammatory reaction, ameliorating oxygenation, and reducing lung injury.3. Triptolide enchances the expression of ABCA1mRNA and protein and inhibitssecretion of TNF-α on rats, which is potential mechanism of lung protection.4. Triptolide enchances the expression of ABCA1mRNA and protein indose-dependent way, specially ranging between25~100μg/kg.