The Role Of MAPK/CPLA2 Signaling Pathway In LPS-induced Intrauterine Infection-induced Bpd And The Intervention Effect Of Glutamine

Research Background:Infection is a key factor in the occurrence of neonatal bronchopulmonary dysplasia(BPD),and intrauterine infection can cause plasma pulmonary infection,the development of new type of BPD is caused by obstruction of alvelar polar process.However,the molecular mechanism of fetal lung injury caused by excessive inflammation after intrauterine infection remains unclear.But mitogen-activated protein kinase/cytoplasmic phospholipase A2(MAPK/cPLA2)signaling plays an important role in inflammation and cell proliferation in many diseases,and the MAPK/cPLA2 signaling pathway is triggered by intrauterine infection.The role in BPD has not been reported yet.Hydrocotisone is commonly used to prevent and treat BPD in premature infants,but its effect is not consistent.Glutamine(Gln)is an important free amino acid in the human body.It plays an important role in maintaining the body’s acid-base balance,regulating the body’s immune function,and providing raw materials for the material and energy metabolism of specific organisms,tissues and even cells,without side effects.Gln has a certain protective effect on immunity,metabolism and anti-oxidation during treatment,and is more important for the nutrition of premature infants.However,the protective effect and mechanism of glutamine on premature BPD have not been reported yet.Therefore,this study analyzed the effectivenessof hydrocortisone-induced pulmonary inflammation and BPD in preterm infants firstly,and used the preterm rat model caused by intrauterine infection to observe and screen the relevant factors and classical signaling pathways involved in the response of the lung disease.On the basis of the double specificity protein phosphatase-against crack the original activated protein kinase phosphatase-1/silk crack the original activated protein kinase/type cytoplasm phospholipase A2(MKP-1/MAPK/cPLA2)signaling pathway.To exolore the anti-inflammatory effect and molecular mechanism of Gln in the occurrence and development of BPD induced by intrauterine infection,aiming to reveal the molecular mechanism of BPD induced by intrauterine infection and the target of Gln’s prevention and treatment of BPD from the perspective of clinical practice and basic experiment,and provide scientific theoretical basis for the prevetion and treatment of neonatal and treatment of neonatal diseases and clinical application of Gln.Objective:(1)Infection can cause lung inflammation and BPD in premature infants,but the clinical treatment effect of hydrocortisone is still uncertain.Therefore,we first analyze the effectiveness of hydrocortisone in preventing and treating pulmonary inflammation and BPD.(2)Observe and screen the related factors and MKP-1/MAPK/cPLA2 signaling pathways involved in the lung inflammatory response using a premature rat model caused by intrauterine infection.(3)Aiming at the MKP-1/M APK/cPLA2 signaling pathway,exp lore the anti-inflammatory effect and molecular mechanism of Gln in the development of BPD induced by intrauterine infection.Methods:(1)The computer searched the PubMed,Embase and Cochrane Library databases from 1997 to 2019 to collect the research literature on the application of hydrocortisone and placebo in premature infants(born at<37 weeks gestational age).The two researchers independently collected.Screen the literature and organize the data.evaluate the risk of bias in the included literature research,and use Review Manager 5.3 software to organize the included researchdata.At the same time,systematically evaluate the effectiveness and safety of early application of hydrocortisone to prevent and treatment BPD in premature infants.(2)Preparation of a rat model of premature BPD induced by LPS-induced intrauterine infection.HE staining was used to observe the pathological morphology of the placenta of pregnant rats.Neonatal rat bronchoalveolar lavage fluid(BALF)and lung tissue were collected to detect the pathological changes of lung tissue HE and lung tissue water content to identify lung inflammation inpreterm rats.Using PCR Array technology to detect differentially expressed inflammation-related factors in lung tissues.locking for possible signal pathways involved in the development and progression of premature BPD induced by LPS-induced intrauterine infection,and using Western Blotting technology to detect the expression of selected signal pathway molecules.and to analyze the possibility of MAPK/cPLA2 signaling pathway participation.(3)The neonatal rats delivered by pregnant rats in intrauterine infection group were randomly divided into intrauterine infection group,intrauterine infection+GLN group.and the neonatal rats delivered by pregnant rats in control group remained the control group,a total of 3 groups.Observe the general condition of newborn rats on days 1,3,5 and7 respectively.determine the amount of leukocyte infiltration,TNF-α,IL-1β,IL-6 and lung tissue water content in BALF,HE staining to observe the pathological manifestations of lung tissue,Quantitative PCR and Western Blotting techniques were used to detect the expression of Bax,Bcl-2,MKP-1,p-ERK,ERK,p-P38,P38,p-cPLA2,cPLA2 and other mRNA and protein expression,and the use of siRNA technology to knock down MKP-After 1 observation of the expression of cPLA2,analyze the possible mechanism of glutamine to protect the key molecules of MKP-1/MAPK/cPLA2 signaling pathway during the development of premature BPD caused by intrauterine infection.Results:(1)There were 11 studies,atotal of 1,435 subjects were included in the study,including 706 cases in the hydrocortisone intervention group and 729cases in the placebo group.Meta-analysis results showed that early(within 1 week after birth)systemic hydrocortisone was applied until the corrected gestational age was 36 weeks,and the chance of survival of preterm infants without BPD was born[RR1.16,95%CI(1.02,1.32),P=0.88]is significantly higher than the control group,and the subgroup with BPD as the main expected target also supports the same result[RR1.22,95%CI(1.08,1.41),P=0.328)];but for preterm birth with BPD In children,studies using systemic hydrocortisone found no clear meaning[RR0.94,95%CI(0.81,1.09)].(2)① A large number of neutrophils infiltrated in the placenta decidua of the intrauterine infection group,accompanied by congestion and edema;②The body weight of the neonatal rats in the intrauterine infection group on the first day after birth was significantly reduced,and in BALF the total number of leukocytes,TNF-α,IL-1β.IL-6 content increased significantly;The lung tissue water content increased significantly and the lung tissue structure was disordered.With the prolonged exposure time of the inflammatory response,the alveolar structure was simplified and the number was significantly reduced,showing a large amount of inflammation Sex cell exudation,some alveolar collapse,hemorrhage,and epithelial cell shedding;③PCR Array results screened 23 high-expression and 21 low-expression differentially expressed mRNA,and the identification of key factors in inflammation-related signaling pathways revealed that MKP-1/MAPK/cPLA2 signaling pathway promotes lung inflammation.(3)①The total number of leukocytes,TNF-α.IL-1β and IL-6 in BALF of newborn rats in glutamine injection group decreased compared with the previous days on the first,third,fifth and seventh day after birth,and the same time point Compared with the intrauterine infection group,the difference was statistically significant(P<0.05);②The body weight of the glutamine injection neonatal group increased significantly with the time of medication,the lung tissue was obviously repaired,the lung tissue was clearer,and the lung tissue water content decreased;③The glutamine group may protect lung inflammation by affecting factors such as MKP-1,ERK,P38MAPK and cPLA2.SiRNA technology knocks down MKP-1:after Gln injection,it can quickly induce MKP-1 expression and down-regulate p-cPLA2 expression.Conclusion:(1)For preterm infants who are not accompanied by BPD at birth,early systemic hydrocortisone is a more effective treatment for preventingBPD in premature infants,but it is meaningless with BPD.Therefore,hydrocortisone is not effective in the treatment of BPD in preterm infants.it is necessary to clarify the mechanism of occurrence and development of BPD in preterm infants and an effective drug development with little side effects.(2)Intrauterine infection can induce lung inflammation and BPD in neonatal rats.MKP-1/MAPK/cPLA2 signaling pathway is involved in the occurrence and development of preterm birth BPD caused by intrauterine infection.(3)Glutamine can relieve pulmonary edema,lung inflammation and apoptosis in premature rats due to intrauterine infection.Its effect protects the occurrence and development of BPD by regulating the MKP-1/MAPK/cPLA2 signaling pathway.Glutamine may become a treatment for premature BPD.