Objective To investgate the expression of p38 mitogen-activated protein kinase （p38MAPK） in lung tissue of rats with severe acute pancreatitis （SAP）， and to explore 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 into 3， 6， 12， and 24 h group， each group enrolled 8 rats， respectively. SAP model rats were established by injecting 5% sodium taurocholate solution retrograde into the biliopancreatic duct. ELISA method was used to test the serum tumor necrosis factor-α （TNF-α） and interleukin-1β （IL-1β）， and pathological changes in lung and pancreas tissues were observed by HE staining. Immunohischemistry method was used to detect phosphorylated p38 （p-p38） protein and aquaporin 1 （AQP1） protein of lung tissues. The expression level of AQP1 mRNA was measured 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 were observed in pancreas tissues of all 4 time point groups. Compared with SO group， levels of serum TNF-α and IL-1β were significantly higher in 4 time point groups （P＜0.05）. Lower expression level of p-p38 protein was detected in lung tissues of SO group， while in the early stage of SAP （SAP 3 h group）， the expression level of p-p38 protein significantly increased， which peaked in 6 h group and was still higher than SO group in 24 h group （P＜0.05）. Compared with SO group， the expression levels of AQP1 mRNA and protein were significantly lower in all 4 time point groups （P＜0.05）， which had negative correlation with the levels of serum TNF-α，IL-1β， and the expression level of p-p38 protein （r=-0.87， P＜0.05；r=-0.88， P＜0.05；r=-0.78， P＜0.05）. Conclusion The decrease of AQP1 protein in lung tissue is one of the vital causes for pulmonary capillary barrier injury in SAP， which probably works by the activation of p38MAPK and the excessive release of inflammatory cytokines.
ObjectiveTo observe the effects of aquaporin 1 (AQP1) on the proliferation and migration of endothelial progenitor-endothelial progenitor cells (EPC).MethodsBone marrow cells of AQP1 wild-type (WT) (n=6) and knockout-type (KO) mice (n=6) were isolated and differentiated into EPC in vitro. Immunofluorescence was used to detect cell surface antigens to identify EPC. Live cell kinetic imaging and quantification technology, transwell migration assays, as well as scratch test were used to compare the function of EPC between AQP1 WT and KO mice.ResultsEPC culture showed that cells were initially suspended and gradually adhered to typical mesenchymal stem cells within 7 days. After cultured on special medium for endothelial cells they were adhered and differentiated, and fusiform or polygonal, paving stone-like EPC were observed around 14 days. When cultured by special medium of EPC, CD133 and CD31 were positively detected after 7 days, and CD34 and Flk-1 were positively detected after 14 days. Positive expression of AQP1 was only detected in EPC of AQP1 WT mice. Functional studies of EPC revealed there was no significant difference in the proliferation of EPC between AQP1 WT and KO group mice. Transwell assay showed that EPC migration ability of AQP1 KO mice was significantly weaker than that of WT mice. The scratch healing ability of EPC in AQP1 KO mice was significantly lower than that of WT mice.ConclusionsEPC initially shows the characteristics of stem cells and with the prolongation of culture time, EPC gradually shows the characteristics of endothelial cells. AQP1 affects the EPC migration rather than proliferation.