Function Of Aquaporin-1 On Acute Lung Injury Induced By Severe Acute Pancreatitis In Rats And Influence Of Chinese Medicine Qingyitang On Expression Of Aquaporin-1

Background and objective Acute lung injury (ALI) is one of the major reasons for death after severe acute pancreatitis (SAP). The mechanism of ALI in SAP is very complex, involving many cytokines and inflammatory factors, such as TNF-α, IL, and so on. The releasing of cytokines enhances the vasopermeability of pneumonic endothelium cell, and induce the lung edema and injury.Aquaporin-1 (AQP-1) was found in lung endothelium cell and regulates the water transport. It was shown that AQP-1 plays the key role in many lung diseases with edema. It was evidenced that Qingyitang reduces the mortality after SAP, but the mechanism is not still clearly. Our study was designed to assess the expression of AQP-1 and the effect of Qingyitang on lung AQP after SAP.MethodsPartⅠWistar rats were divided into two groups randomly (n=24): SHAM and ALI groups. The sodium deoxycholate (15g/l) were retrograde infused to the bile-pancreatic duct for producing the pancreatitis with acute lung injury (ALI group), SHAM group were performed all the surgery proceed without drugs. 4, 8 and 12 hours after operation, blood and lung tissue were collected (n=8). Lung wet/dry ratio, blood-gas, blood amylase were investigated. The expression of AQP-1 mRNA in lung tissue were detected by RT-PCR, and the protein expression of AQP-1 in lung tissue were detected by immunohistochemistry and Western blot.PartⅡ72 Wistar rats were divided into three groups randomly (n=24):SHAM, ALT and DEX groups. The sodium deoxycholate (15g/l) were retrograde infused to the bile- pancreatic duct for producing the pancreatitis with acute lung injury (ALI group), the surgery proceed without drugs were performed to SHAM group, DEX group treated with dexamethasone (2mg/kg) through the femoral vein immediately after pancreatitis. After operation 4, 8 and 12 hours, the expression of AQP-1 mRNA in lung tissue were detected by RT-PCR, and the protein expression of AQP-1 in lung tissue were detected by immunohistochemistry and Western blot. Alsoly, blood and lung tissue were collected (n=8). Lung wet/dry ratio, blood-gas, blood amylase, TNF-αwere investigated.PartⅢWistar rats were divided four groups randomly: SHAM group, ALI group, DEX group and QYT group(n=8). The methods of SHAM group, ALI group, DEX group were same with Part two. Qingyitang (2ml/100g BG) were given by gavage immediately after pacreatitis(QYT group). Blood and lung tissue were collected 8 hours after pacreatitis. Lung wet/dry ratio, blood-gas, blood amylase, TNF-αwere investigated. The expression of AQP-1 mRNA in lung tissue were detected by RT-PCR, and the protein expression of AQP-1 in lung tissue were detected by immunohistochemistry and Western blot.Statistical analysis: All data are expressed as mean±SD. One way ANOVA was used for analysis in measurement data. And Person Correlation was used for analysis of correlations. P<0.05 was considered statistically significant.ResultsPartⅠCompared with SHAM group, the serum amylase and the W/D were increased significantly but decreased on the level of PaO2 in ALI group(P<0.01). In every time point respectively, the pathological change of pulmonary tissue was also significant. There are expressions of AQP-1 mRNA in the SHAM group, however the expression of AQP-1 mRNA and protein were markly down-regulated in ALI group(P<0.01), and the the expression of AQP-1 mRNA and protein were increased significantly according to the time longer.PartⅡThe level of TNF-αwas increased in ALI group comparing with SHAM group (P<0.01), but significantly decreased in DEX group(P<0.05).With the increasing of TNF-αin ALI group, the expression of AQP-1 mRNA and protein were decreased. With the decreasing of TNF-αin DEX group, the expression of AQP-1 mRNA and protein were increased respectively. There is correlation between the level of serum TNF-αand the expression of AQP-1 in pulmonary tissue according to the correlation analysis (P<0.05).PartⅢIn QYT group, the level of serum amylase, W/D, PO2, serum TNF-αand the pathological change of pulmonary tissue were similar with DEX group. The above date were statistically significant comparing with ALI group. The expression of AQP-1 mRNA and protein were also similar. Compared with ALI group, The expression of AQP-1 mRNA and protein were increased significantly (P<0.05), and relevantly the lung edama was decreased.ConclusionsThere are strong relationships between AQP-1 and edema of lung. And the SAP releases many cytokines and inflammatory factors, therefore induces the ALI. TNF-αis the major mediator. Based on our results, in ALI group TNF-αwas enhanced with the lower expression of AQP-1. However, DEX and QYT reverse this effect. QYT and DEX protect the lung from SAP injury by up-regulating the AQP-1 through the suppressing of TNF-α. These data have shown that QYT and DEX protect the lung function after SAP. Improving the expression of AQP-1 and reducing the level of TNF-αin lung are the major mechanisms.