Effects Of Bone Marrow Mesenchymal Stem Cells On P38MAPK In Acute Lung Injury Rats With Severe Acute Pancreatitis

This study includes two parts, we observed the expressions of p38mitogen-activated protein kinase in acute lung injury with severe acute pancreatitis inthe first part, to explore the mechanism of p38mitogen-activated protein kinase inacute lung injury with SAP; To explore the therapeutic mechanism by allogeneicBMSCs, research on whether it can inhibit the activity of p38MAPK, reduce thelevels of serum inflammatory factors and regulate the AQP1expression, provide theexperimental basis for the future treatment of BMSCs on SAP.Part1Expressions of p38mitogen-activated protein kinase and pulmonary capillarybarrier injury in rats with severe acute pancreatitisObjective To investgate the expression of p38mitogen-activated protein kinase（p38MAPK） in lung tissue of rats with severe acute pancreatitis （SAP）， and toexplore the relationship between p38MAPK and pulmonary capillary barrier injury.Methods Forty male and healthy sprague-dawley（SD）rats were randomly（random number method）divided into sham operation（SO）group and SAP group，then rats of SAP group were sub-divided into3h、6h、12h， and24h group， eachgroup enrolled8rats， respectively. SAP model rats were established by injecting5%sodium taurocholate solution retrograde into the biliopancreatic duct. The automaticbiochemical analyzer was used to detect the level of serum amylase.Elisa method wasused to test the serum tumor necrosis factor-α（TNF-α）and interleukin-1β（IL-1β），and pathological changes in lung and pancreatitis were observed by HE staining.Immunohischemistry method was used to detect phosphorylated p38（p-p38）proteinand aquaporin1（AQP1）of lung tissues. The expression level of AQP1mRNA wasmeasured by quantitative real-time PCR.Results Hyperemia，edema，and inflammatory cell infiltration were observed in lung tissues，abundance of necrosis，part gland structure fuzzy or even disappear wereobserved in pancreatic tissues of each4time point groups. Compared with SO group，levels of serum amylase,TNF-α and IL-1β were significantly higher in4time pointgroups（P＜0.05）. Lower expression level of p-p38protein was detected in lungtissues of SO group， while in the early stage of SAP（SAP3h group），theexpression level of p-p38protein significantly increased， which peaked in6h groupand was still higher than SO group in24h group （P＜0.05）. Compared with SOgroup，the expression levels of AQP1mRNA and protein were significantly lower in4time points group（P＜0.05），which had negative correlation with the levels ofserum TNF-α，IL-1β，and the expression level of p-p38protein（r=-0.87，P＜0.05；r=-0.88，P＜0.05；r=-0.78，P＜0.05）.Conclusion The decrease of AQP1in lung tissues is one of the vital causes forpulmonary capillary barrier injury in SAP，which probably works by the activation ofp38MAPK and the excessive release of inflammatory cytokines.Part2Effects of bone mesenchymal stem cells on pulmonary capillary leakage in ratswith severe acute pantreatitisObjective To investigate the protective effects and mechanism of bonemesenchymal stem cells(BMSCs) on pulmonary capillary leakage in rats with severeacute pantreatitis.Methods Fifty-six male Sprague-Dawly rats were randomly divided into shamoperation(SO) group, model control(SAP) group and treatment(BMSCs) group, thenboth SAP group and BMSCs group were sub-divided into6h,12h,24h groups with8rats in each one. SAP model was made by retrograde injection of5%sodiumtaurocholate solution into the biliopancreatic duct,the BMSCs group received BMSCsinfusion through femoral vein. The automatic biochemical analyzer was used to detectthe level of serum amylase. Elisa method was used to test the serum tumor necrosisfactor-α（TNF-α）and interleukin-1β（IL-1β），and pathological changes in lung andpancreatitis were observed by HE staining. Immunohischemistry method was used to detect phosphorylated p38（p-p38）protein and aquaporin1（AQP1）of lung tissues.The expression level of AQP1mRNA was measured by quantitative real-time PCR.Results The concentration of serum amylase, TNF-α, IL-1β and pathologicalchanges of lung and pancreatic tissues were significantly higher at all time points inthe SAP group than in the SO group. Compared with the SO group, the proteinexpression of p-p38MAPK in lung tissues was significantly increased, the expressionof AQP1was significantly decreased in SAP group and BMSCs group. Comparedwith the SAP group, the protein expression of p-p38MAPK in lung tissues wassignificantly decreased, the expression of AQP1was significantly increased inBMSCs group, while the pathological damage of lung and pancreatic tissues andserum amylase and inflammatory factors were decreased.Conclusion The BMSCs can significantly protect acute lung injury in theprogress of severe acute pantreatitis, probably through inhibiting the activity ofp38MAPK and reducing the levels of serum inflammatory factors.