The Effect Of Diallyl Trisulfide On The Expression Of Pulmonary Surfactant Proteins SP-A And SP-B In ALI Mice Induced By Lipopolysaccharide

Objective: Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) were definited as acute, progressive, stubborn respiratory failure with stubborn hypoxemia induced by different predisposing factors (such as sepsis, trauma and shock) except cardiogenic causes, which were progressed as a major component of multiple organ dysfunction syndrome (MODS). The pathophysiological pathogenesis of ALI and ARDS is similar, but the severity is different, ARDS is the severe endpoint of ALI.Entoxin released by Gram-negative bacteria is the main cause of ALI/ARDS. Lipololysaccharide (LPS), the main outer membrane component of entoxin of Gram-negative bacteria, is the most common reagent to duplicate ALI/ARDS model. The model is similar to ALI/ARDS patients in clinic induced by severe infection. Not only microvascular endothelium and alveolar epithelium is injuried, vascular permeability increase and the formation of pulmonary edema and hyaline membrane is well established, but also the metabolism and function of pulmonary surfactant(PS) is changed by LPS in ALI/ARDS. Surfactant proteints(SP) SP-A and SP-B are effective ingredients of PS system. SP-A in coordination with SP-B is contributed to the formation and metabolism of PS. Their function, synthesis, secretion and regulation are complicated. SP-A and SP-B are played an important role in pathophysiological mechanism of ALI/ARDS.Diallyl trisulfide (DATS) is the main effective component in garlic extract. Modern medicine has demonstrated that garlic extracts have the effect of broad-spectrum antimicrobial activity in bacteria infection and invasive fungous infection. Zhu guijun et al, reported that DATS maybe have chemoprevention effects on inhibiting expression and production of proinflammatory cytokines, example of TNF-αand IL-1β, in pulmonary alveolar macrophage strain(MH-S) of ALI mice induced by LPS. DATS also can remarkably decrease nuclear factor kappa B (NF-κB) activation and the phosphorylation level of inhibitoryκB (IκB) in the lung tissue of ALI mice. These studies sugessted that DATS maybe have chemoprevention effects on ALI/ARDS. In this study, we duplicated LPS-induced ALI mice model and investigated pathology, the lung W/D ratio and the effect of DATS on the expression of SP-A and SP-B mRNA in ALI mice induced by LPS, in order to provide breadboard evaluation for prevention of ALI/ARDS in clinic.Methods: Onehundred and thirty healthy kun-ming mice were randomly divided into five groups: (1) ALI group: mice were infused the same bulk as DATS of sodium chloride intraperitoneally for 7 days, and then received LPS 10mg/kg injection; (2) DATS prevention group: mice were infused (2mg/ml)DATS 30mg/kg intraperitoneally for 7 days and then received LPS 10mg/kg injection; (3) DATS treatment group: mice were infused the same bulk as DATS of sodium chloride intraperitoneally for 7 days, then received LPS 10mg/kg injection, and after 30 minute they received (2mg/ml) DATS 30mgl/kg injection; (4) DATS group: mice received (2mg/ml) DATS 30mg/kg injection intraperitoneally for 7 days and without LPS injection; (5) Control group: mice were infused the same bulk as DATS sodium chloride intraperitoneally for 7 days and without LPS injection. Mice in each group (n=6) were executed by taking off the neck at 2h and 6h. The degree of pulmonary edema was assessed with the lung wet/dry weight (W/D). The expression of SP-A, SP-B mRNA in the lung tissues was detected with reveuse transcription-PCR (RT-PCR) and was semi-quantitatively analyzed by Gel-Pro Analyzer software. Data were presented as ?x±s and analyzed with ANOVA, least significant difference (LSD) and independent-samples T Test using SPSS 12.0 statistical program. A level of P<0.05 was considered to be statistically significant. The histopathology changes of lung tissues were examined with HE stain lung-biopsy specimen under light microscopy after mice in each group (n=2) being infused LPS 12h.Result:1 The changes of the lung W/D ratio in ALI miceAt 2h of ALI group, no changes were detected in the lung W/D compared with that in control group (P>0.05). At 6h of ALI group, the lung W/D was significantly elevated (P<0.05 vs control group), and pulmonary edema was visable, while it was reduced in DATS prevention group (P<0.05 vs ALI group). But no decrease was observed in DATS treatment group (P>0.05). There were no difference between DATS group and control group (P>0.05).2 The histopathology changes of lung tissureLung gross anotomy: no abnormal histomorphology changes were found in control group and DATS group. In ALI group, the lung was heavy and swelling in dark red color with diffuse spots. The lung parenchymal surface was curmbly and was rich of erythroic edema fluid. The pathological changes were lessened obviously in DATS prevention group compare with that in ALI group. But the histomorphology changes were similar between DATS treatment group and ALI group. Light microscopy: the lung structure including alveolar space and alveolar septum were normal without edema in control group and DATS group. But there were alveolar septum widening, capillary congestion, interstitial and alveolar edema, intra-alveolar hemorrhage, and multiple inflammatory cells infiltration in the lungs of ALI mice. Pretreatment with DATS could significantly alleviate the lung injury of ALI. However, no significantly influence was found in DATS treatment group.3 SP-A and SP-B mRNA expression in the lung tissues of mice After infused LPS 2h and 6h, declined SP-A and SP-B mRNA expression level was all observed in the lungs of ALI group (P<0.05vs control group), which were all obviously enhanced by pretreatment with DATS for 7 days (P<0.05 vs ALI group). But the expression of SP-A and SP-B mRNA in the lungs of DATS prevention group still lower than control group significantly (P<0.05 vs control group). In the DATS treatment group, the expression of SP-A and SP-B mRNA did not change significantly (P>0.05 vs ALI group). DATS alone group had no influence on the expression of SP-A and SP-B mRNA in the lung tissues (P>0.05 vs control group). At 2h and 6h, the respective expression of SP-A and SP-B mRNA in the lungs of the same group had no change siginifcantly (P>0.05 vs control group).Conclusion: In this study, we investigated the preventive and therapeutic effect of DATS on ALI mice induced by LPS from the histopathology changes of lung tissues, the lung W/D ratio to SP-A and SP-B mRNA expression. We draw someconclusion:1 Pretreatment with DATS could alleviate the degree of pulmonary edema and pulmonary inflammation;2 Pretreatment with DATS could enhance SP-A and SP-B mRNA expression.Our study demonstrates that DATS may be an effective chemopreventive reagent to reduce the risk of ALI/ARDS, especially for the patients with serious infection and trauma, which are the high risk factors of ALI/ARDS and can increases the survival rate of high risk patients effectively.