The Role Of IL-8 In The Pathogenesis Of Lung Injury Associated With Severe Acute Pancreatitis And The Therapeutic Effects Of Qingyi Pellet Intervention

Acute pancreatitis?AP?is one of the most acute and critical diseases in the clinical surgery.10%to 30%of the patients may develop into severe acute pancreatitis?SAP?.Acute lung injury?ALI?is one of the most common complications of SAP.In most cases,the pathogenesis of ALI is related to endotoxin translocation,inflammatory cell activation and a variety of inflammatory factors like cascade reaction.Even more,ALI could gradually transform into systemic inflammatory response syndrome?SIRS?or multiple organ dysfunction syndrome?MODS?.A large number of studies have shown that the severity of ALI/ARDS is positively correlated with the number of neutrophil?PMN?in pulmonary capillaries,interstitium and alveoli.When PMN is inhibited or cleared,the severity of lung injury is significantly decreased.Otherwise ALI will occur quickly.PMN plays a very significant role in the pathogenesis of ALI:?1?After activation,inflammatory factors such as TNF-?,IL-1,IL-6 and IL-8 can be activated by PMN in chemokine.PMN's ability is reduced via inflammatory factors to deform so that they accumulate in large amounts in the lung microvessels,and PMN can cause more inflammatory factors in the body to be activated through a variety of inflammatory pathways which can lead to a cascade reaction,aggravate the condition;the number of PMN can be increased by IL-8-adherent endothelial cells,then PMN is lead to accumulate in a large number of inflammation sites and damage to the body;?2?PMN can release damaging enzymes such as collagenase,cathepsin and elastase.Structural proteins can be degraded and digested by collagenase in lung tissue and the destruction of the basement membrane of alveolar capillaries can be caused;the surface anticoagulant activity of endothelial cells can be reduced via cathepsins.PMN is made easier to adhere and impair coagulation function;elastase can change pulmonary alveolar permeability caused by pulmonary edema,destroy pulmonary microvascular endothelial cells to make PMN easier to pass through,destroy alveolar epithelial cells to cause reduced surface activity,and damage coagulation factors causing clotting disorders.?3?PMN can reduce plasma's resistance to reactive oxygen species and increase reactive oxygen species.Various degrees of damage can be caused to lipids and proteins in the body.Oxygen metabolites can cause lipid peroxidation and thus biofilm lipids.Quality damage can affect the membrane protein by changing the protein structure and enzyme activity.Cells die or reduce the body's antioxidant capacity can be also made;?4?ALI/ARDS is affected by PMN through the regulation of NF-?B pathway.Adhesion and swimming out were happened about PMN and large numbers of PMN were gathered in the location of inflammation.The interaction of PMN and endothelial cells is increased by interaction between ICAM-1 and CD11/CD18.The alveolar epithelial cell is damaged by releasing inflammatory factors from PMN.As a result,the permeability of endothelial cells is increased,pulmonary surfactant is decomposed,then the alveolar compliance is reduced when surface tension is increased which can consume more energy when inhaling.The number of PMN in the tissue is increased because of the accumulation at site of inflammation.in addition,the apoptosis is decreased sharply via the inflammatory mediator which makes PMN activated continuously and SIRS is caused eventually.Because of the function of IL-8,CD11/CD18 could transfer to the cell surface from the intracellular library of PMN.At the same time,the L-selectin on the surface of PMN is dropped and deformed due to the influence of IL-8.As one of the CXC chemokine proteins,IL-8 has a similar binding site of nuclear factor-?appa B?NF-?B?which is similar to IL-6.It can be produced by vascular endothelial cells?VEC?under the induction of TNF-?.PMN in the bone marrow can be released into the peripheral blood by stimulation of IL-8.After binding IL-8 to CXCR1/CXCR2,PMN is recruited to the wound site and adhered to VEC,then the inflammatory response is aggravated.Over the years of the clinical observation and experiment,our researches have shown the function of Qingyi decoction:heat and detoxifying toxin is clear away,blood circulation is activated and blood stasis is removed which can effectively prevent acute pancreatitis and lung injury.Qingyi decoction has been widely used in clinical and has achieved good results.The prescriptions of rhubarb and bupleurum are the main drugs.Also the main components of Dachaihu decoction are from"Jin Kui Yao Lue".Recent studies have shown that inflammation induced by SAP can be reduced via Qingyi decoction and the organ damage can be protected to prevent its failure.Although the experimental study and clinical observation of Qingyi decoction in the treatment of SAP have been widely reported,the pathogenesis of AP and the therapeutic effect has made a significant progress.However,the pathogenesis of AP-ALI and the specific intervention mechanism of Qingyi decoction have not yet been fully understood.Especially,the expression of genes and proteins,signal transduction,and the relationship between inflammatory factors need to be further explored.Purpose:in this experiment,we used the pellets made from the reformed Qingyi decoction instead to conduct relevant observations.In this study,retrograde injection of sodium deoxycholate into the biliary and pancreatic ducts was used to prepare rat model of AP to investigate the mechanism of IL-8 in neutrophils and its role in the pathogenesis of AP-ALI.Methods:Fifty SPF male SD rats were randomly divided into five groups:normal control group?SHAM group,n=8?;severe acute pancreatitis model group?SAP group,n=10?;IL-8 antibody group?IL-8 Ab group,n=10?;Dexamethasone group?DEX group,n=10?;Qingyi pellet group?QYKL group,n=12?.The SHAM group only opened the abdominal cavity and then flipped the pancreas several times;In SAP group,SAP animal models were prepared by retrograde injection of 15 g/L sodium deoxycholate?1 m L/kg body mass?;In IL-8 Ab group,IL-8 antibody was administered via tail vein injection immediately after modeling;In the DEX group,5 g/L dexamethasone injection was given intraperitoneally immediately after modeling;The QYKL group was intragastrically administered with Qingyi pellet solution for 30 min.Rats in all groups were sacrificed 24 hours after surgery and the tissues were taken.Part of the lung and pancreas tissues were stained by HE and the corresponding pathological scores were recorded..The wet/dry ratio of lung tissue was measured by vacuum drying.The blood was taken from abdominal aorta and blood gas analysis was performed.The expression level of TNF-?and IL-8 in rat serum was measured by ELISA.The content of serum amylase was detected by automatic biochemical analyzer.The protein expression of ICAM-1 in lung tissue was detected by Western-Blot and the gene expression of ICAM1 was detected by RT-qPCR.Results:Compared with SHAM group,the histological scores of pancreas and lung in SAP group were increased?p<0.05?;the wet/dry ratio of lung tissue in SAP group was significantly higher?p<0.05?;PaO₂ in SAP group decreased significantly?p<0.05?,PaCO₂ in SAP group increased significantly?p<0.05?;the serum levels of TNF-?,IL-8and amylase in SAP group were obviously increased?p<0.05?;Expression of ICAM-1protein in lung tissue was significantly increased by western blot?p<0.05?;Expression of ICAM1 gene in lung tissue was increased by RT-qPCR?p<0.05?.Compared with the SAP group,the Chinese medicine treatment group and the IL-8 and dexamethasone treatment groups all improved in various degrees,but it can be seen that IL-8 and dexamethasone not only have a single effect but also have certain side effects.Qingyi pellet has a multi-faceted,multi-level,multi-target comprehensive treatment effect.Conclusion:?1?After modeling,there were obvious pathological changes in the pancreas and lung tissues of the rats,serum amylase was significantly elevated,blood gas analysis showed significant changes,lung wet/dry ratio was significantly increased.Acute pancreatitis and lung injury occurred in model rats,indicating that the acute pancreatitis lung injury model was successfully prepared.?2?Qingyi pellet may reduce the accumulation of neutrophils in the lung tissue by inhibiting the chemotactic activity of IL-8,so as to reduce the strong inflammatory response of the pancreas and lung tissues,and thereby reduce the lung injury.Qingyi pellet has obvious comprehensive therapeutic effect on the prevention and treatment of lung injury in acute pancreatitis.