| Objective: in this study,the changes of TLR4 signal transduction pathway and Mesenchymal stem cells(MSCs)in the LPS rat model of acute lung injury ALI were studied to understand the pathogenesis of ALI.To investigate the effect of aerosolized inhalation of lysophosphatidic acid(LPA)on lps-induced acute lung injury in rats,and to promote the repair of lung injury by increasing the number of MSCs and inhibiting the inflammatory response of TLR4 signal transduction pathway.Methods: 60 SD rats were randomly divided into 5 groups: the rat caudal vein injection of PBS and LPS respectively set to normal group(NC group),sepsis,acute lung injury group(LPS group),lung injury in rats,intravenous LPA antagonists Ki 16425(LPS+KI group),the LPS group and LPS+KI atomization set respectively in the treatment of lung injury in rats atomization LPA group(LPS+LPA group),LPA the treatment group(LPS+LPA+KI group).The rats were anesthetized on the first day(d1)and the seventh day(d7)of atomized LPA,respectively,and the lung tissues were collected after anatomy for pathological HE staining and wet/dry weight measurement.Peripheral blood was collected and the concentrations of TLR4,NFk B,IL-6 and IL-21 were detected by ELISA.TLR4 m RNA and LPA receptor m RNA were detected by rt-pcr.Western bolt detection of NFk B/ p-NFk B,ERK/p-ERK protein expression,flow cytometry detection of MSCs surface markers related antibodies,MSCs percentage calculation of each group,to study the impact of LPA on the number of MSCs.Results: HE staining results showed that large area of infiltration and hemorrhage of alveolar and interstitial inflammatory cells could be seen under d1 microscope in LPS group,with thickened septum;while infiltration and hemorrhage of alveolar and interstitial inflammatory cells could be seen under d7 microscope,with thickened septum,partial necrosis of alveolar epithelium and transparent membrane formation.Under the microscope,a small number of alveolar and interstitial inflammatory cells infiltration and mild hemorrhage were observed in the LPS+LPA group,and the septum was slightly thickened and most transparent membranes were repaired.Meanwhile,the wet/dry weight of lung tissue in the LPS group was higher than that in the normal group,and the wet/dry weight ratio of lung tissue in the LPS+LPA group was lower than that in the LPS group(p<0.01),which proved that the modeling of each group was successful.ELISA showed that the expressions of TLR4,NFk B,IL-6 and IL-21 in LPS group were higher than those in normal group(p<0.001).The expressions of TLR4,NFk B,IL-6 and IL-21 in LPS+LPA group were lower than those in LPS group(p<0.01).The expressions of TLR4,NFk B,IL-6 and IL-21 in LPS+LPA group were higher than those in LPS+LPA group(p<0.01).Rt-pcr experiment showed that the expression of TLR4 m RNA in lung tissues of LPS group was significantly increased(p<0.01),the expression of TLR4 m RNA in LPS+LPA group was significantly decreased compared with LPS group(p<0.001),and the expression of TLR4 m RNA in LPS+LPA+KI group was significantly increased compared with LPS+LPA group(p<0.01,p<0.001).TLR4 m RNA expression in LPS+LPA+KI group was lower than that in LPS+LPA group(p<0.01).The protein expression of p-NFk B in LPS+LPA group was significantly higher than that in LPS group(p<0.01).The protein expression of p-NFk B in LPS+LPA+KI group was significantly higher than that in LPS+LPA group(p<0.05).The protein expression of p-ERK in LPS+LPA group was significantly lower than that in LPS+LPA group(p<0.01).The protein expression of p-ERK in LPS+LPA+KI group was significantly lower than that in LPS+LPA group(p<0.01).MSCs% in LPS+LPA group was significantly higher than that in LPS group and normal group(p<0.01),and MSCs% in LPS+LPA+KI group was significantly lower than that in LPS+LPA group(p<0.05).Conclusion: 1,ALI model pathological microscopically pulmonary inflammatory cell infiltration and hemorrhage,thick septa,lung wet/dry weight at the same time more normal group increased obviously,prove that ALI rats building success,and LPS caused ALI rats serum inflammatory cytokines(TLR4,NFk B,IL-6,IL-21),increased expression of lung tissue TLR4 m RNA and higher protein expression of p-NFk B,LPS in ALI in TLR4 way involved in the inflammatory response.2,Atomization LPA can reduce LPS caused ALI rats serum inflammatory cytokines(TLR4,NFk B,IL-6,IL-21),lung tissue TLR4 m RNA expression and p-NFk B protein expression,and raised the lungs p-ERK protein expression and increase the number of MSCs,pathology,seen here in a pulmonary inflammatory cells infiltration,hemorrhage,transparent membrane repair,show that LPA by inhibiting TLR4 signaling pathways activated and increase the number of MSCs to repair of sepsis lung injury,to improve the prognosis of sepsis lung injury provides a new train of thought.3.In the KI model of LPA inhibitor,the infiltration and hemorrhage of inflammatory cells in the lung were worsened,and the expressions of inflammatory factors(TLR4,NFk B IL-6,IL-21)in the serum of rats were increased compared with the LPS group,and the expressions of TLR4 m RNA and p-NFk B protein in the lung tissue were increased compared with the LPS group,while the expression of p-ERK protein and the number of MSCs LPS group were decreased compared with the LPS group.Reverse validation showed that LPA could repair sepsis lung injury by inhibiting the activation of TLR4 signaling pathway and increasing the number of MSCs... |
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