Study On Acute Respiratory Distress Syndrome Induced By Endotoxin And Protecting Effects Of Fufangkushenzhusheye In Rabbits

Objective：Acute respiratory distress syndrome (ARDS) is a kind of serious diseasewhich threatens people health with high mortality rate. However, the pathogenesis hasnot been clarified yet. ARDS models of white rabbits were replicated with escherichiacoli endotoxin（the main pathogenic component of lipopolysaccharide LPS） injected soas to observe the pathophysiology changes by endotoxin (ET) in rabbits and investigatethe mechanism of acute respiratory distress syndrome and the protective effect ofFufangkushen injiection in ARDS．Methods：Twenty-one male New-Zealand flap-eared white rabbits were randomlyassigned to three groups：control group(A)，injury group(B)and therapeutic group(C)．There are seven animals in each group．All animals were anesthetized with25%urethane(4ml/kg)through peritoneal cavity．Rabbits in group A received saline(4m1/kg)．Group B and C were intravenously injected LPS(720ug/kg)dissolved in saline．Group Cwere identical to group B but received Fufangkushen(4ml/kg)the same time to LPS.Theparameters were measured as follows:1.The vital signs including breath rate,blood pressure were recorded at0h,0.5h,lh,2h,4h.2.The arterial blood gas were measured at0h,0.5h,lh,2h,4h.3.The lung wet to dry weight ratio was determined.4. Each group lung tissue pathological changes were observed under light microscope.5.TREM-1,MPO,TNF-α,ICAM-1,AQP-1and VEGF were observed on each group lungtissue through immunohistochemical method.Results：1.The observed targets in group A are stable during the experiment and there are nostatistic different between the three groups.2. The vital signs and arterial blood gas were measured. (1).Respiratio:After injecting LPS, the tachypnea appeared in group B,the fastestfrequency was about78times/min,the most significant changes happened at0.5h,respiratory frequency decreased gradually. The Group C also appeared to slowdown after the change of trend.(2).Blood pressure: During the whole experiment,group A maintained at above93mmHg. The blood pressure in group B was definitely lower than that in groupA(P<0.01) after injecting LPS at0.5h. The tendency of blood pressure in group Cwas descent.(3).The arterial blood gas analysis: The values of group A were in the normal range.after LPS injection,the partial pressure of oxygen and oxygenation index weredecreased in group B,they degraded to55.23mmHg and258.07mmHg(p<0.01,compared with group A) at0.5h, meeting the standard of ARDS and both indexanastated later.The partial pressure of oxygen and oxygenation index decreased tooin group C,but it did not get to the standard and partly was higher than that in groupB(P<0.01).The partial pressure of carbon dioxide was degrading both in group Band C.3. Results after4h, lung wet/dry ratio in group B was significantly higher than that ofgroup A(P<0.01), the group C was obviously higher than that in group A(P<0.01)but lower than that of group B (P<0.05).4. The lung tissue pathological examination: Group A had basically normal alveolarstructure, which was no obvious hemorrhage and exudation in alveolar. Group Bshowed alveolar septal thickening, congestion, pulmonary edema, and smallalveolar cavity with neutrophil infiltration，sticking to the wall.The visible reddyed substance scattered in the clustering with partial visible focal atelectasis.Alveolar septum thickened slightly in group C which alveolar cavity was biggerthan that of group B, the infiltration of inflammatory cells and pulmonarycongestion and edema reduced.lung injury eased more than group B.5. The expression of TREM-1by immunohistochemistry: It was not obvious in groupA. A large amount of dark brown particles showed in alveolar septum, neutrophils ingroup B,which reduced significantly in group C. 6. The results of MPO: There was nearly no expression in group A.The group Bpositive products distributed in the alveolar walls, alveolar septum and the cellmembrane of neutrophils was brown, which decreased in group C.7. The expression of TNF-α: A little pale yellow flake or granular product expressed inalveolar spaces of group A.The positive products were brown or dark brown ingroup B, distributed in the lung neutrophils and macrophages’ cytoplasm. Group Cpositive expression product was weakened which compared with group B.8. The positive products of ICAM-1: No ICAM-1expression in normal lung tissue of A groupA.A lot of dark brown particles appeared in alveolar septum and vascular endothelialcells’ cytoplasm. Group C showed dark brown granules of varying amounts, butcompared with the injury group were significantly reduced.9. The results of AQP-1expression:It was no expression in group A.The positiveproducts were brown, mainly expressed in alveolar septum and the cytoplasm ofalveolar epithelial cells in Group B.There is little inflammatory cell infiltration ingroup C alveolar cavity. the expression of group C reduced.10. The expression of VEGF: VEGF is low expression level in normal lung tissue,whileexpressed significantly in group B.the expression products were pale brown，distributed in the vascular endothelial cells and alveolar epithelial cells’ membraneor the cytoplasm. Alveolar septum thickened slightly in group C and the pale brownpositive products decreased obviously. The expression of VEGF in group C reduced.Determination of results：No stain was negative.Pale yellow was weakly positive(+)，deep brown was strong positive (+++)，moderate positive was between weaklypositive and strong positive (++).Conclusion1.ARDS models can be replicated with intravascular lipopolysaccharide(LPS)injection(720ug/kg).2. Inflammatory reaction of ARDS was out of control, Inflammatory reaction andanti-inflammatory reaction balance is imbalance.3. The lung tissue injuryed by endotoxin occurs endothelial cell swelling,inflammatorycell infiltration, microcirculation and a series of pathophysiological changes. 4. The expression of positive products by immunohistochemistry on TREM-1，MPO，TNF-α，ICAM-1，AQP-1and VEGF was significantly in injury groups.However,theexpression weakened in the protection group by fufangkushenzhusheye.5. Fufangkushen has anti-inflammatory, anti stress and improving immunity， It caninhibit the adhesion to vascular endothelial cells，maintain the integrity of theendothelial cells by reducing the permeability of endothelial cells and play aprotective role to the damaged lung tissue.