Effect Of CRRT On Endothelial Injury Induced By The Serum From SAP Patients With Lung Injury

Background: Pulmonary complications are the most frequent and potentially the most serious in the early phase of severe acute pancreatitis (SAP). There is a direct correlation between mortality and hypoxemia which is caused by acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) occurred in the early phase of SAP. Continuous renal replacement therapy (CRRT) has been shown to have considerable benefit for the treatment of ALI/ARDS secondary to SAP. However, it is unclear the pathophysiological mechanism of improvement of the gas exchange function of lung in SAP patients with lung injury during CRRT.Methods: Prospectively own control study. 131 cases of SAP patients with lung injury were involved; however, only 86 cases of patients entered the experiment in the end. All patients were treated with CRRT and routine therapy. The change of PaO2, PaO2/FiO2, (A-a)DO2, Qs/Qt, APARCHE?score and respiratory rate were observed during CRRT.Results: The level of PaO2?PaO2/FiO2 increased greatly, (A-a)DO2, Qs/Qt, the respiratory rate and APACHE?score decreased significantly at 6-hour?12-hour and 20-hour time point during CRRT, compared with pre-CRRT time point. The level of PaO2 and PaO2/FiO2 reached the highest at 6-hour time point during CRRT, and then dropped a little at 12-hour and 20-hour time point; while (A-a)DO2 and Qs/Qt, R and APACHE?scores reached the lowest at 6-hour time point during CRRT, and then increased a little at 12-hour and 20-hour time point. There was a significant difference between 6-hour time point and 12-hour or 20-hour time point. All of these SAP patients with lung injury was divided into 2 subgroups: 200 mmHg?PaO2/FiO2 < 300 mmHg group and PaO2/FiO2<200 mmHg group; both of the 2 subgroups has the same results. We also found that the difference of PaO2, PaO2/FiO2, (A-a)DO2, Qs/Qt between post-CRRT and pre-CRRT (DPaO2,DP/F, DA-a and Ds/t) at 6-hour time point was higher than that at 20-hour time point; but no difference was found between the 200 mmHg?PaO2/FiO2 < 300 mmHg group and PaO2/FiO2 < 200 mmHg group at 6-hour time point and 20-hour time point.Conclusion: Intrapulmonary shunts and gas exchange and oxygenation were improved greatly in SAP patients with lung injury after CRRT, especially at 6-hour time point. Background:Pulmonary complications are the most frequent and potentially the most serious in the early phase of severe acute pancreatitis(SAP). Influx of protein-rich edematous fluid into the airspaces due to increased permeability of the alveolar-capillary barrier is a key mechanism of ALI and ARDS. And endothelial apoptosis may contribute to endothelium barrier dysfunction. Continuous renal replacement therapy (CRRT) has been shown to have considerable benefit for the treatment of ALI/ARDS secondary to SAP. However, it is unclear whether the protective effect on lung by CRRT depends on the inhibition of endothelial apoptosis.Methods: Serum samples and waste replacement fluid were taken from the SAP patients with ALI/ARDS at special time point during CRRT, from the SAP patients without lung injury, and from the healthy volunteers as control. The HUVEC (Human Umbilical Vein Endothelial Cells) were treated with the serum or the waste replacement fluid in vitro. Cells viability and apoptosis were examined by MTT assay and flow cytometry, Caspase3 were determined by immunofluorescent staining, ILK mRNA and protein expression were measured by RT-PCR and Western blot analysis, and the level of superoxide anion in the serum, waste replacement fluid and cells was determined.Results: The endothelial apoptosis and the Caspase 3 expression induced by the serum from the SAP patients with or without lung injury before CRRT and by the waste replacement fluid from the SAP patients with ALI/ARDS at 2-hour time point during CRRT significantly increased, and the cells viability, ILK mRNA expression and ILK protein expression decreased significantly. The more serious lung injury was, the more serious endothelial apoptosis induced by the serum from the patients was. A negative correlation was found between the endothelia apoptosis and the PaO2/FiO2. The endothelial apoptosis and Caspase 3 expression induced by the serum from the SAP patients with ALI/ARDS after CRRT decreased significantly, and the cells viability?ILK mRNA expression and ILK protein expression increased significantly. The ILK mRNA expression and ILK protein expression increased and the Caspase 3 expression decreased more in the cells induced by serum group of 6h after CRRT than those in the cells induced by serum group of 20h after CRRT. However, no difference of endothelial apoptosis and cells viability was found between the cells induced by serum groups of 6h, 20h after CRRT. The level of superoxide anion in serum from SAP patients with ALI/ARDS before CRRT was higher than the normal control, after CRRT, the level of superoxide anion decreased significantly. The level of superoxide anion in the cells induced by serum from SAP patients with ALI/ARDS was higher than that in the cells induced by serum from the normal control; the level of superoxide anion in the cells induced by serum from SAP patients with ALI/ARDS after CRRT decreased significantly. However, the level of superoxide anion in the cells induced by serum from SAP patients with ALI/ARDS at 20-hour time point after CRRT was higher than that in the cells induced by serum from SAP patients with ALI/ARDS at 6-hour time point after CRRT. There was a negative correlation between the oxgenation index of SAP patients with ALI/ARDS at 6-hour time point during CRRT and the endothelial apoptosis induced by the serum from these patients, between the level of superoxide anion in the serum of SAP patients with ALI/ARDS and the ILK expression induced by the serum from these patients, between the ILK expression and the endothelial apoptosis, the ILK expression and the superoxide anion production in the endothelial cells induced by the serum from the SAP patients with ALI/ARDS. There was a positive correlation between the ILK expression and the cells viability in the endothelial cells induced by the serum from the SAP patients with ALI/ARDS. The cells viability, ILK mRNA expression and ILK protein expression decreased, and the endothelial apoptosis, the superoxide anion production and the Caspase 3 expression increased in the cells induced by the waste replacement fluid from the SAP patients with ALI/ARDS at 2-hour time point during CRRT.Conclusion: The endothelial apoptosis involved in ALI/ARDS due to SAP could be inhibitted after CRRT. By CRRT, the ameliortion of oxidative stress and increase in the expression of ILK in ECs may be an important signaling pathway of anti-apoptosis for SAP patients with ALI/ARDS. The filter being changed timely may improve the anti-apoptosis effect of CRRT. Background:In the early phase of severe acute pancreatitis (SAP), serious pulmonary complications are very common. The key mechanism of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) is the influx of protein-rich edema fluid into the airspaces, which is caused by increased permeability of the alveolar-capillary barrier. However, it is unclear whether continuous renal replacement therapy (CRRT) could protect lung by inhibiting endothelial permeability.Methods: Serum samples and waste replacement fluid were taken from the SAP patients with ALI/ARDS at the special time point during CRRT, from the SAP patients without lung injury, and from the healthy volunteers as control. The endothelial cells (ECs) were treated with the serum or the waste replacement fluid in vitro. Cell permeability was examined. F-actin was detected by immunofluorescent staining with confocalmicroscopy. Rho A protein was detected by Western blot, and the level of superoxide anion was determined.Results: The endothelial permeability and the Rho A expression induced by the serum from the patients with or without ALI/ARDS following SAP before CRRT and induced by the waste replacement fluid at 2-hour time point during CRRT increased significantly. The more serious lung injury was, the more serious endothelial permeability induced by the serum from the patients was. After CRRT, the cells permeability and Rho A expression induced by the serum from the patients with ALI/ARDS decreased. However, no difference was found between the cells induced by serum groups of 6h, 20h after CRRT. Increased stress F-actin and superoxide anion in cells induced by the serum or by waste replacement fluid were inhibited after CRRT. A positive correlation was found between Rho A expression and endothelial permeability, and between Rho A expression and superoxide anion levels.Conclusion: The endothelial hyper-permeability involved in ALI/ARDS due to SAP could be inhibitted after CRRT. By CRTT, the amelioration of oxidative stress and decrease in Rho A expression in ECs may inhibit endothelial hyper-permeability. The filter being changed timely may improve the anti-permeability effect of CRRT.