ABSTRACT
OBJECTIVES@#To study the role of adrenomedullin (ADM) in hyperoxia-induced lung injury by examining the effect of ADM on the expression of calcitonin receptor-like receptor (CRLR), receptor activity-modifying protein 2 (RAMP2), extracellular signal-regulated kinase (ERK), and protein kinase B (PKB) in human pulmonary microvascular endothelial cells (HPMECs) under different experimental conditions.@*METHODS@#HPMECs were randomly divided into an air group and a hyperoxia group (@*RESULTS@#Compared with the air group, the hyperoxia group had significant increases in the mRNA and protein expression levels of ADM, CRLR, RAMP2, ERK1/2, and PKB (@*CONCLUSIONS@#ERK1/2 and PKB may be the downstream targets of the ADM signaling pathway. ADM mediates the ERK/PKB signaling pathway by regulating CRLR/RAMP2 and participates in the protection of hyperoxia-induced lung injury.
Subject(s)
Humans , Adrenomedullin/genetics , Endothelial Cells , Hyperoxia/complications , Lung Injury , Receptor Activity-Modifying ProteinsABSTRACT
Mammals exposured to high volume fractional oxygen (hyperoxygen) are prone to go under oxidative stress, and activating inflammatory cells in the lung produce cytotoxic reactive oxygen species directly or indirectly, activate complex signaling pathways and epigenetic factors, causing lung epithelial cells and endothelial cell damage and death. In the hyperoxia-induced lung injury-related signaling pathways, the current research includes MAPK pathway, P13K/Akt pathway, TGF-β related pathway, NF-κB pathway, Wnt pathway, Rho/Rock pathway, Notch pathway, Shh pathway, AngⅡ-P22phox-ROS pathway, Src pathway and so on. This review summarizes the research of these signaling pathways in hyperoxia-induced lung injury.
ABSTRACT
Objective To observe the expressions of long noncoding RNA (IncRNA)metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) and nuclear factor etythroid-2 related factor 2 (Nrf2) in lung tissues of hyperoxia-exposed premature neonatal rats,and explore the role of MALAT1 and Nrf2 in hyperoxia-induced lung injury.Methods Pregnant Sprague-Dawley (SD) rats were given cesarean section on the 21st day of gestation.After feeding for 24 h,a total of 80 premature rats were randomly divided into the air group and hyperoxia group.The rats in the air group were fed in the indoor environment[fraction of inspiration O2 (FiO2) =210 mL/L] and those in the hyperoxia group were fed in a high-oxygen box (FiO2 ＞ 850 mL/L).Eight premature rats from each group were sacrificed and lung tissue samples were collected at 5 experimental time points (1st,4th,7th,10th,14th day),respectively.Hematoxylin-eosin staining was used to observe pathological changes in lung tissues.Real-time quantitative polymerase chain reaction (qPCR) and Western blot were used to detect the expression level of MALAT1and Nrf2.Results Compared with the air group,the degree of alveolarization in lung tissues of the hyperoxia group rats was reduced,and radial alveolar count (RAC) decreased on the 1st day,but there was no significant difference between 2 groups (P ＞0.05),when they decreased on the 4th(3.14 ± 0.23),7th(5.25 ± 0.38),10th (4.41 ± 0.44),14th (3.41 ± 0.13) day of exposure,the differences were statistically significant (all P ＜ 0.05).Compared with the air group,the RNA expression of MALAT1 of hyperoxia group preterm rats decreased after the 1 st day(0.527 ± 0.124) of exposure,increased after the 4th (0.538 ±0.128),7th (0.748 ±0.071) day,decreased after the 10th (0.519 ± 0.081)day,and the differences were statistically significant (all P ＜ 0.05),but it continually became weak on the 14th day,but there was no significant difference between 2 groups (P ＞ 0.05).Compared with the air group,the mRNA expression of Nrf2 of hyperoxia group preterm rats decreased after the 1st day(0.791 ± 0.031) of exposure,increased after the 4th (0.977 ± 0.189),7 th (1.369 ± 0.100),10th (1.094 ± 0.104) day,and the differences were statistically significant (all P ＜ 0.05),and it decreased after the 14th day,but there was no significant difference between 2 groups (P ＞0.05).The hyperoxia group had significantly higher expression of free Nrf2 protein and lower expression of Nrf2-Keapl protein than those of the air group at all time points.Within the hyperoxia group,the RNA expression of MALAT1 was positively correlated with RAC and Nrf2 (r =0.517,0.533,all P ＜ 0.001).Conclusions Lung injury is gradually aggravated over the time of hyperoxia exposure.The level of lncRNA MALAT1 is associated with the severity of lung injury and the level of Nrf2 mRNA,suggesting that IncRNA MALAT1 and the Nrf2 target gene signaling pathway might be involved in the development of hyperoxia-induced lung injury in neonatal premature rats together.
ABSTRACT
Objective To observe and comparatively analysize the effect of intraperitoneal injection of hydrogen and hydrogen-rich saline in neonatal rats with hyperoxia-induced lung injury.Methods Sprague-Dawley(SD) newborn rats were randomly divided into six groups(n=10).air group(A),air+ hydrogen-rich saline group(B),air+hydrogen group(C),hyperoxia group(D),hyperoxia+hydrogen-rich saline group (E) and hyperoxia+ hydrogen group(F).The group A,B and C were exposed to air and group D,E and F were exposed to 95 ％ oxygen.The group B and E were intraperitoneally injected with hydrogen-rich saline (10 mL/kg,twice daily),while the groups C and F with hydrogen (10 mL/kg,twice daily).The group A and D were injected with normal saline(10 mL/kg,twice daily).Lung tissue and serum samples were collected on 15 d of experiment.The pathological changes of lung tissue and radiate alveoli count (RAC) were observed by HE staining.The content of HYP in lung tissue was detected by the alkaline hydrolysis method,serum SOD and MDA levels were measured.The expression of α-SMA in lung tissue was detected by immunohistochemistry SP method.Results Compared with the A group,RAC and SOD activities in the D group were significantly decreased,while the HYP and MDA levels and α-SMA expression were significantly increased.Hydrogen intervention could significantly alleviate these changes caused by hyperoxia.while intraperitoneal injection of hydrogen got better effect than intraperitoneal injection of hydrogen-rich saline.Conclusion Hydrogen can extenuate the indexes of hyperoxia-induced lung oxidative damage,impairment development and fibrosis to a certain extent.Intraperitoneal injection of hydrogen has slightly better effect than hydrogen-rich saline.
ABSTRACT
Objective To explore the effects of endoplasmic reticulum (ER) stress in the hyperoxia-induced lung injury in premature rats. Methods Forty-eight premature Wistar rats were randomized into two groups 12 hours after birth:hyperoxia group (n=24) inhaled 95%oxygen and control group (n=24) inhaled air. Eight rats were sacriifced in each group on day 1, 3, 7 after the treatment and the left lungs were embedded. The pathological changes in the HE stained sections of lung tissues were observed. The expressions of ER related protein ERp57 and c/EBP homologous protein CHOP were detected by immuno histo-chemistry and the apoptosis of lung cells was detected by TUNEL analysis. Results The typical pathological characteristics of acute lung injury were observed in hyperoxia group. The expressions of ERp57 and CHOP were increased with the exposure time in hyperoxia group, and were signiifcantly higher than in control group (P<0.05). The apoptosis rate of lung cells in hyperoxia group was signiifcantly higher than in control group (P<0.01). There was signiifcant positive correlation between cell apoptosis index and expressions of Erp57 and c/EBP homogeneous protein. Conclusions ER stress initiated apoptosis participates and plays an important role in the process of hyperoxia-induced lung injury in premature rats.
ABSTRACT
Objective To explore the survival/proliferation,apoptotic and death effects of keratinocyte growth factor (KGF) in alveolar epithelial type Ⅱ cells (AT Ⅱ Cs) exposed to hyperoxia.Methods Primary culture of AT Ⅱ Cs from the Sprague-Dawley rat fetuses was studied under room air condition (210 mL/L O2) and hyperoxic condition (950 mL/L O2) for 0.5-12.0 h.Various concentrations of KGF (15 μg/L,25 μg/L,50 μg/L,75 μg/L,100 μg/L)were added into the cell cultures.Cells were randomly divided into room-air group,room-air-KGF group,hyperoxic-exposure group and hyperoxic-exposure-KGF group.The levels of intracellular reactive oxygen species (ROS),cleaved cysteinyl aspartate specific proteinase-3 (Caspase-3),cell death and proliferation of AT Ⅱ Cs were measured by flow cytometer,Western Blot,release of lactate dehydrogenase assays (LDH assays) and 3-(4,5-Dimethyhhiazol-2-yl)-2,5-diphenyhetrazolium bromide assays (MTT assays),respectively.Results Under room air condition,KGF could significantly increase AT Ⅱ Cs proliferation with 15-100 μg/L in a dose-dependent manner and significantly decrease LDH production at concentrations of 25-100 μg/L.Exposure to hyperoxia resulted in a significant increase in intracellular ROS production in AT Ⅱ Cs in a time-dependent manner compared with that of the room air group.Cell viability decreased and LDH release increased significantly in a time-dependent manner when AT Ⅱ Cs were exposed to 950 mL/L O2 for more than 4 h.After exposure to hyperoxia for 0.5 h and 1 h,KGF could significantly increase AT Ⅱ Cs proliferation in 15-75 μ g/L and significantly decrease LDH production at concentrations of 25-75 μg/L.After exposure to hyperoxia up to 4 h,higher viability was observed in 15 μg/L and 25 μg/L KGF group,and lower death rate presented in 25-100 μg/L KGF group.Further,prolnged hyperoxic exposure for 8 h,high viabilitv was shown only in 50 μg/L KGF group,and less death rate was observed only in 75 μg/L KGF group.In addition,no significant difference in viability and mortality was found between hyperoxic group and hyperoxic-KGF group after hyperoxic exposure for 12 h.Expression of cleaved Caspase-3 was significant higher after 4 h and 8 h hyperoxic exposure than that in room-air group ;at the same time,by adding 25 μg/L and 75.μg/L KGF led to decreased expression of Caspase-3 was detected,compared to hyperoxic group.Conclusions KGF may promote survival/proliferation,inhibited apoptosis and death of rat fetal AT Ⅱ Cs in room air condition or under temporary exposure to hyperoxia in vitro.However,prolonged exposure to hyperoxia may decrease the sensitivity of AEC Ⅱ Cs to KGF and limit its protective effects on lung injury.
ABSTRACT
Objective To explore the effect of hyperoxia on A549 cells suppressed with surfactant protein A (SP-A) suppressed by small interference RNA(SiRNA)-mediated gene silencing,and discuss the function of SP-A in hyperoxic lung injury.Methods A549 cells were gained by serial sub cultivation in vitro and randomly divided into 2 groups,silenced of SP-A group and the control group.A549 cells were transfected with synthetic SP-A sequence-specific SiRNA by Lipofectamine 2000,continuously exposed to hyperoxia(950 mL/L 02,50 mL/L CO2).After exposure to hyperoxia for 48 hours,72 hours and 96 hours,total protein and culture supernatant were gained.SP-A protein was detected by Western-blot,the capacity of proliferation was detected by methyl thiazolyl tetrazolium,and thiobarbituric acid colorimetric method was used to detect the malondialdehyde (MDA) in culture supernatant.Results Sequence-specific SiRNA targeted SP-A2 and significantly down-regulated its expression in A549 cells.Compared with the control group in hyperoxia,the expression of SP-A significantly decreased after 48 hours,72 hours in the silenced group (all P ＜ 0.05),and the capacity of proliferation in A549 cells silenced by SP-A were obviously decreased after 48 hours,72 hours and 96 hours(all P ＜0.05).But there was no significant difference in the MDA in culture supernatant between 2 groups(all P ＞ 0.05).Conclusions The capacity of resisting hyperoxia decreased in A549 cells silenced by SP-A,which indicates that SP-A can protect hyperoxic lung injury.
ABSTRACT
Hyperoxia-induced lung injury in neonatal is a common complication after the clinical high oxygen therapy. There is not specific and effective prevention and treatment. Recent research suggests that many factor play an important role in the repair and protection of hyperoxia-induced lung injury in neonatal, such as growth factor, bone marrow mesenchymal stem cells,erythropoietin, anti-chemokine and anti-oxidation. The article reviews the molecular systems mechanisms in the pathologic process of hyperroxia-induced lung injury in neonatal.
ABSTRACT
Animal experiments and clinical studies both support the inflammatory response involved in the process of hyperoxia-induced lung injury,but the inflammation and its influence is fairly complicated. A variety of cytokines expression and inflammatory cells infiltration in hyperoxic lung injury form the basis of changes in inflammatory injury.