MicroRNA Expression Profiles in the Neonatal Rat Hippocampus Exposed to Normobaric Hyperoxia

Objective: This study aimed to identify differentially expressed microRNAs (miRNAs) using microarray and to predict special target genes using bioinformatics methods in the neonatal rat hippocampus after normobaric hyperoxia exposure, and to unravel the molecular mechanisms of developing brain injury induced by normobaric hyperoxia. Methods: Eight neonatal Sprague-Dawley rats at postnatal 1 day were divided equally between a control group and an experimental group, followed by 24-hour exposure to 21% oxygen and (95 ± 5) % oxygen, respectively. Total RNAs were extracted from the rat hippocampus. Three samples were randomly selected from each group to detect differentially expressed mRNA profiles using the affymetrix GeneChip Rat Genome 230 2.0 Array. Differentially expressed miRNA profiles were determined by miRNA enrichment analysis. The starBase software was applied to predict target genes abundantly expressed in the hippocampus, and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses were conducted for bioinformatics analysis. Results: Microarray analysis revealed 681 differentially expressed miRNAs in the neonatal rat hippocampus after normobaric hyperoxia exposure. Only one miRNA, miR-489-5p, was significantly upregulated (P Mdfic. The other 680 miRNAs were significantly downregulated (P P Gjb6 and Bnc2. KEGG analysis indicated that differentially expressed miRNAs were closely related to multiple signaling pathways. Conclusions: Differentially expressed miRNA profiles in the neonatal rat hippocampus after normobaric hyperoxia exposure may be involved in the physiopathological processes of developmental midbrain injury induced by normobaric hyperoxia.

氧浓度变化对人肺动脉内皮细胞中ANGPTL8表达的影响

目的探讨氧浓度变化对肺动脉内皮细胞(HPAECs)中血管生成素样蛋白8(ANGPTL8)表达的影响,以及ANGPTL8在肺动脉高压(PH)中的作用和机制。方法低氧(1%)和高氧(85%)处理HPAECs,Western blot和PCR等检测ANGPTL8的表达,并分析内皮-间质转化(EndMT)及ERK信号通路的变化。同时,高氧处理新生大鼠,构建支气管肺发育不良(BPD)模型,观察肺组织中ANGPTL8蛋白表达及ERK信号通路的变化。结果低氧组HPAECs中ANGPTL8的蛋白表达显著升高,伴随ERK信号通路的抑制(P<0.05)。ANGPTL8促进低氧诱导的EndMT过程(P<0.05),沉默ANGPTL8可以部分逆转EndMT过程。高氧组HPAECs和大鼠肺组织中ANGPTL8蛋白表达降低,伴随ERK信号通路的激活(P<0.05)。结论HPAECs中ANGPTL8对氧浓度变化高度敏感,其表达的变化与ERK信号通路的活性状态密切相关,对PH的发展具有潜在的调控作用。

CFTR氯离子通道在Ⅱ型肺泡上皮细胞高氧损伤机制的研究

目的 研究囊性纤维化跨膜转导调节因子(CFTR)氯离子通道在Ⅱ型肺泡上皮细胞(AECⅡ)高氧损伤中的作用。方法 AECⅡ于密封舱中通入95%O_(2)+5%CO_(2),持续24h或48h,构建高氧损伤AECⅡ模型。将实验组AECⅡ随机分为高氧24h组、高氧24h+激动剂(Gen)组、高氧24h+抑制剂(AA)、高氧48h组、高氧48h+Gen组和高氧48h+AA组;对照组通入空气,未干预。以膜片钳系统记录CFTR氯离子电流强度。细胞外液中分别加入GEN50μM或AA10μM,记录GEN激活或AA抑制后氯离子电流强度。采用Clampfit 10.6行数据分析,应用R4.4.1统计软件对不同组别行Spearman相关性分析。结果 1.高氧24h、48h明显抑制AECⅡ氯离子电流(P<0.01),以24h较明显;2. Gen明显增加高氧24h、48hAECⅡ氯离子电流;AA明显抑制氯离子电流(P<0.01),均以48h较明显。结论 高氧可能通过影响AECⅡCFTR氯离子外流而发挥作用。

脐带间充质干细胞治疗高氧新生大鼠肺损伤的研究

目的探讨脐带间充质干细胞(UC-MSC)移植治疗高氧导致的新生大鼠肺损伤的疗效及可能的调控机制。方法从人脐带中分离间充质干细胞并进行体外培养,流式细胞术鉴定细胞表型;新生大鼠36只随机分为3组,分别为对照组、模型组和治疗组,除对照组外,其余两组大鼠均置于高压氧箱内饲养,建立肺损伤模型,对照组置于室内空气中饲养,造模4 d后,治疗组给予细胞注射,对照组和模型组给予生理盐水注射。2周后处死新生大鼠,测定各组大鼠肺组织湿/干重比值,组织切片染色观察各组大鼠肺组织病理学情况、血管肌化情况和微血管密度情况;测定各组大鼠肺组织活性氧(ROS)、髓过氧化物酶(MPO)活性和丙二醛(MDA)、IL-6、IL-1β和TNF-α的表达水平。结果与对照组新生大鼠相比,模型组新生大鼠肺组织湿/干重比值、ROS活性、MPO活性、MDA含量均增高,炎症因子IL-6、IL-1β和TNF-α的表达水平均升高,显示造模成功;治疗组与模型组相比,肺组织湿/干重比值、ROS活性、MPO活性、MDA含量均降低,炎症因子IL-6、IL-1β和TNF-α的表达水平均降低,肺组织水肿和炎性细胞浸润情况明显好于模型组,血管肌化情况显著减轻,微血管密度显著增高。结论UC-MSC能显著改善高氧环境下导致的新生大鼠肺损伤程度,具有一定的修复作用。

早产儿高氧导致脑损伤的研究进展

新生儿重症监护室(NICU)技术的发展,使得氧疗普遍应用于早产儿抢救治疗中,提高了早产儿存活率。然而,与高氧相关的早产儿脑病(EOP)、早产儿视网膜病(ROP)和支气管肺发育不良(BPD)等并发症严重影响存活早产儿的生存质量。本文综述了高氧导致脑损伤的临床及动物实验研究现状,明确与高氧相关早产儿神经系统损伤可能的表现及机制,为早产儿临床安全用氧决策提供理论依据。

Mechanism of Retinoic Acid and Mitogen-activated Protein Kinases Regulating Hyperoxia Lung Injury

To investigate the protective effect of retinoic acid （RA） on hyperoxic lung injury and the role of RA as a modulator on mitogen-activated protein kinases （MAPKs）, gastation 21 d Sprague- Dawley （SD） fetuses （term = 22 d） were delivered by hysterotomy. Within 12-24 h of birth, premature rat pups were randomly divided into 4 groups （n= 12 each） ： air-exposed control group （group Ⅰ ） ; hyperoxia-exposed group （ group Ⅱ ）, air-exposed plus RA group （group Ⅲ ）, hyperoxia-exposed plus RA group （group Ⅳ）. Group Ⅰ , Ⅲ were kept in room air, and group Ⅱ , Ⅳ were placed in 85 % oxygen. The pups in groups Ⅲ and Ⅳ were intraperitoneally injected with RA （500 μg/kg every day）. All lung tissues of premature rat pups were collected at the 4th day after birth. Terminal transferase d-UTP nick end labeling （TUNEL） staining was used for the detection of cell apoptosis. The expression of PCNA was immunohistochemically detected. Western blot analysis was employed for the determination of phosphorylated and total nonphosphorylated ERKs, JNKs or p38. Our results showed that lungs from the pups exposed to hyperoxia for 4 d exhibited TUNEL-positive nuclei increased markedly throughout the parenchyma （P〈0.01）, and decreased significantly after RA treatment （P〈0.01）. The index of PCNA-positive cells was significantly decreased （P〈0.01）, and was significantly increased by RA treatment （P〈0.01）. The air-space size was significantly enlarged, secondary crests were markedly decreased in hyperoxia-exposed animals. RA treatment improved lung air spaces and secondary crests in air-exposed pups, hut had no effect on hyperoxia-exposure pups. Western blotting showed that the amounts of JNK, p38 and ERK proteins in hyperoxia-exposure or RA-treated lung tissues were same as those in untreated lung tissues （P〈0.05）, whereas activation of these MAPKs was markedly altered by hyperoxia and RA. After hyperoxia exposure, p-ERK1/2, p-JNK1/2 and p-p38 were dramatically increased （P〈0.01）, whereas p-JNK1/2 and p-p38 were markedly declined and p-ERK1/2 was further elevated by RA treatment （P〈0.01）. It is concluded that RA could decrease cell apoptosis and stimulate cell proliferation under hyperoxic condition. The protection Of RA on hyperoxia-induced lung injury was related＇to the regulation of MAP kinase activation.

Effect of Amygdalin on the Proliferation of Hyperoxia-exposed Type Ⅱ Alveolar Epithelial Cells Isolated from Premature Rat

Summary: The pathogenesis of hyperoxia lung injury and the mechanism of amygdalin on type 2 alveolar epithelial cells (AEC2) isolated from premature rat lungs in vitro were investigated. AEC2 were obtained by primary culture from 20-days fetal rat lung and hyperoxia-exposed cell model was established. Cell proliferating viability was examined by MTT assay after treatment of amygdalin at various concentrations. DNA content and the proliferating cell nuclear antigen (PCNA) protein expression of AEC2 were measured by using flow cytometry and immunocytochemistry respectively after 24 h of hyperoxia exposure or amygdalin treatment. The results showed that hyperoxia inhibited the proliferation and decreased PCNA protein expression in AEC2 of premature rat in vitro. Amygdalin at the concentration range of 50-200 μmol/L stimulated the proliferation of AEC2 in a dose-dependent manner, however, 400 μmol/L amygdalin inhibited the proliferation of AEC2. Amygdalin at the concentration of 200 μmol/L played its best role in facilitating proliferation of AEC2s in vitro and could partially ameliorated the changes of proliferation in hyperoxia exposed AEC2 of premature rat. It has been suggested that hyperoxia inhibited the proliferation of AEC2s of premature rat, which may contribute to hyperoxia lung injury. Amygdalin may play partial protective role in hyperoxia-induced lung injury.

Temporal Expression of Notch in Preterm Rat Lungs Exposed to Hyperoxia

Summary: To explore the mechanism of Notch in hyperoxia-induced preterm rat lung injury, 2-days-old preterm SD rats were randomized into control and hyperoxia group (FiO 2≥0.85). On day 1, 7, 14 and 21, 8 rat pups of each time point were used to assess histopathological changes of lung with HE staining and to evaluate the expression of Notch1 and Notch3 with immunohistochemistry. Notch1, Notch3, Aquaprin5 (AQP5) and surfactant protein C (SP-C) mRNA were measured by reverse transcription polymerase chain reaction (RT-PCR). The results showed that the lung injury in the hyperoxia group was characterized by retarded lung alveolization and differentiation of alveolar epithelial type Ⅱcells (AEC Ⅱ). Positive staining of Notch1 in hyperoxia group was weaker than controls at every time point (except for day 7), while positive staining of Notch3 was much stronger (P<0.05, P<0.01). Notch1, Notch3 mRNA level showed similar change as protein level. AQP5, SP-C mRNA decreased significantly as compared with that of the controls (P<0.01). We are led to conclude that hyperoxia results in abnormal expression of Notch, which is likely to contribute to the pathogenesis of lung injury through regulating proliferation and transdifferentiation of alveolar epithelial cells.

Effect of overexpression of hypoxia-inducible factor-1α induced by hyperoxia in vivo in LNCaP tumors on tumor growth rate

Objective:To study effect of overexpression of hypoxia-inducible factor-1_α induced by hyperoxia in vivo in LNCaP tumors on tumor growth rate.Methods:The prostate cancer LNCaP cells were inoculated in the abdomen of mice.All the mice were randomly placed in the gas chamber with different oxygen content.The groups were divided as follows:twelve mice in hypoxia group,sixteen mice in normoxia group,ten mice in hyperoxia group.After 28 d of treatment,the mice were weighed,the blood samples were taken from the left ventricle,and the tumor was isolated and weighed.Tumor growth,angiogenesis and vascularization,HIF-1_α expression and intracellular signal transduction molecules expression in each group of xenografts were detected and analyzed by using Western blotting and immunofluorescence and determination of hemoglobin.Results:Comparison of the growth of xenografts in each group showed that,the xenografts growth of hypoxia group was more quickly than that of normoxia group.The difference was statistically significant(P=0.Q04).The difference in xenografts growth between hyperoxia group compared and normoxia group was not statistically significant(P>0.05).The expressions of HIF-1_α,VEGF and VEGF-R of xenografts in hyperoxia group were significantly higher than those of normoxia group(P<0.05).The expression of HIF-1_α of xenografts in hypoxia group and normoxia group were similar.The blood growth rate of xenografts in hypoxia group(170%) was significantly higher than that of normoxia group(40%)(P<0.05).The expression of Nrf2 of xenografts in hyperoxia group was significantly higher than that of normoxia group(P<0.05).Conclusions:When hyperoxia induces the overexpression of HIF-1_α in LNCaP tumor,it will not affect tumor growth.It provides a new ideas and theoretical basis for the clinical treatment of prostate cancer.

Effect of Retinoic Acid on Lung Injury in Hyperoxia-Exposed Newborn Rats

To investigate whether treatment with retinoic acid (RA) could improve level of lung alveolarization and influence lung collagen in newborn rats exposed to hyperoxia, newborn Sprague-Dawley rats aged 2 days were randomly assigned to 8 groups:(1) air, (2) O 2, (3) air+NS, (4) O 2+NS, (5) air+dex, (6) O 2+dex, (7) air+RA and (8) O 2+RA. Group 2, 4 6 and 8 were kept in chambers containing 85 % oxygen, the values were checked 3 times a day. The other 4 groups were exposed to room air. Level of alveolarization and lung collagen were analyzed at age of 14 or 21 days through radial alveolar counts, alveolar airspace measurements, type Ⅰ, Ⅲ collagen immunohistochemical methods (SP method) and image processing system. Transforming growth factor-β receptors and procollagen mRNA accumulation were examined at age of 14 days through immunohistochemical methods and in situ hybridization. Our results showed that radial alveolar counts were increased and distal airspace was enlarged in group 8. TypeⅠcollagen was markedly increased, and transforming growth factor-β receptors and procollagen mRNA were decreased by retinoic acid in bronchial epithelial cells, alveolar epithelial cells and alveolar intersitium. It is concluded that retinoic acid can partially reverse lung development arrest during exposure to hyperoxia by increasing lung collagen.

Comparison of lens oxidative damage induced by vitrectomy and/or hyperoxia in rabbits

AIM： To compare of lens oxidative damage induced by vitrectomy and/or hyperoxia in rabbit.METHODS： Sixteen New Zealand rabbits （2.4-2.5 kg） were randomly divided into two groups （Group A, n=12; Group B, n=4）. In Group A, the right eyes were treated with vitrectomy and systemic hyperoxia （oxygen concentration： 80%-85%, 1 ATA, 4h/d） （Group A-right）, and the left eyes were treated with hyperoxia without vitrectomy surgery （Group A-left）. Four rabbits in group B （eight eyes） were untreated as the controls. Lens transparency was monitored with a slit lamp and recorded before and after vitrectomy. After hyperoxic treatment for 6mo, the eyeballs were removed and the lens cortices （containing the capsules） and nuclei were separated for further morphological and biochemical evaluation.RESULTS： Six months after treatments, there were no significant morphological changes in the lenses in any experimental group when observed with a slit lamp. However, the levels of water-soluble proteins and ascorbate, and the activities of catalase and Na＋-K＋-ATPase were significantly reduced, whereas the levels of malondialdehyde and transforming growth factor β2 （TGF-β2） were significantly elevated, in both the cortices and nuclei of eyes treated with vitrectomy and hyperoxia. The increase in protein-glutathione mixed disulfides and the reduction in water-soluble proteins were more obvious in the lens nuclei. The levels of ascorbate in the vitreous fluid were also reduced after vitrectomy, whereas TGF-β2 increased after vitrectomy and hyperoxia. Systemic hyperoxia exposure increased these effects. CONCLUSION： Removal of the intact vitreous gel with vitrectomy and exposing the lens to increased oxygen from the retina induce lens oxidation and aggregation. Thus, an intact vitreous gel structure may protect the lens from oxidative insult and maintain lens transparency.

Hyperoxia accelerates progression of hepatic fibrosis by up-regulation of transforming growth factor-β expression

AIM: To investigate the effect of hypoxia or hyperoxia on the progression of hepatic fibrosis and to examine the role of transforming growth factor-&#x003b2; (TGF-&#x003b2;) in the livers of rats exposed to hypoxic or hyperoxic conditions.

Effects of Hyperoxia on the Dynamic Expression of Aquaporin5 in Premature Rats Lung Development

To explore the dynamic expression and role of Aquaporin5 ( AQP5) in lung development and hyperoxia lung injury, gestation 21-day Sprague-Dawley (SD) rats (term=22 days) were ran- domly assigned to air group and hyperoxia group within 12-24 h after birth. The rats in hypreoxia group were continuously exposed to about 85% oxygen and those in air group to room air. After 1 to 14 days of exposure, total lung RNA was extracted and the expression of AQP5 mRNA was detected by reverse transcription polymerase chain reaction (RT-PCR). Immunohistochemistry and west- ern-blot were used to detect the expression of AQP5 protein. The results showed that the expression of AQP5 in premature rats lung could be detected at various time points after birth, and the positive staining was restricted to the type Ⅰ alveolar epithelial cells. In air group, the AQP5 expression was detected in a very low level at day 1, but exhibited a persistent increase after birth. Compared with the air group, the expression of AQP5 in hyperoxia group was increased at day 1, and had significant difference in mRNA level (P<0.05), but decreased significantly in mRNA and protein levels after 4 to 14 days (P<0.01 or P<0.05 respectively). It was concluded that AQP5 might play a key role in the alveolar period of premature rats by regulating the lung water balance. Hyperoxia exposure leads to a down-regulation of the AQP5 expression, which may be an important factor for the development of hyperoxia lung injury.

Relationship between Notch Receptors and Hyperoxia-induced Lung Injury in Newborn Rats

Summary: To investigate role of Notch1-3 in hyperoxia-induced lung injury in newborn rat exposed to 85% O 2, SD rat litters born on the 22th day were randomly divided into two groups: room air group and hyperoxia group. The animals were sacrificed 1, 4, 7, 10, 14 and 21 days after continued exposure to oxygen (n=40, oxygen>0.85) or room air (n=40). 6 rats each group were used to assess lung histological changes by HE staining and expression of Notch in lungs by immunohistochemistry. Total RNA was extracted by Trizol reagent from frozen lung tissues. Notch mRNA were measured by reverse transcription polymerase chain reaction (RT-PCR). Our results showed that 7, 14 and 21 days after O 2 exposure, hyperoxia group showed lung injury characterized by pulmonary edema, hemorrhage and lung development arrest. Positive staining for Notch1, Notch 2 in hyperoxia group was much lower than those in room air group at all time points (P<0.01, P<0.05), but compared with the controls, the hyperoxia group showed higher expression of Notch3 (P>0.05). Immunostained cells were typically airways epithelia, alveolar epithelial and inflammatory cells, and fibroblasts in hyperoxia group (P<0.01). Notch mRNA levels showed similar change as protein level (P< 0.01). It is concluded that the prolonged exposure to 85 % O 2 resulted in abnormal expression of Notch receptors, which might contribute to the pathogenesis of hyperoxia-induced lung injury in newborn rats. The decreased inhibition of Notch1 might be one of the protective reaction and major mechanisms for proliferation/differentiation of type Ⅱ alveolar epithelial cells. The up-regulation of Notch3 activity might result in the lung development arrest of the newborn rats.

Retinoic Aacid Diminished the Expression of MMP-2 in Hyperoxia-exposed Premature Rat Lung Fibroblasts through Regulating Mitogen-activated Protein Kinases

This study examined the effects of retinoic acid （RA）, PD98059, SP600125 and SB203580 on the hyperoxia-induced expression and regulation of matrix metalloproteinase-2 （MMP-2） and metalloproteinase-2 （TIMP-2） in premature rat lung fibroblasts （LFs）. LFs were exposed to hyperoxia or room air for 12 h in the presence of RA and the kinase inhibitors PD98059 （ERK1/2）, SP600125 （JNK1/2） and SB203580 （p38） respectively. The expression levels of MMP-2 and TIMP-2 mRNA were detected by semi-quantitative reverse transcription polymerase chain reaction （RT-PCR）. MMP-2 activity was measured by zymography. The amount of p-ERK1/2, REK1/2, p-JNK1/2, JNK1/2, p-p38 and p38 was determined by Western blotting. The results showed that： （1） PD98059, SP600125 and SB203580 significantly inhibited p-ERK1/2, p-JNK1/2 and p-p38 respectively in LFs; （2） The expression of MMP-2 mRNA in LFs exposed to hyperoxia was decreased after treatment with RA, SP600125 and SB203580 respectively （P0.01 or 0.05）, but did not change after treatment with PD98059 （P0.05）. Meanwhile, RA, PD98059, SP600125 and SB203580 had no effect on the expression of TIMP-2 mRNA in LFs exposed to room air or hyperoxia （P0.05）; （3） The expression of pro- and active MMP-2 experienced no change after treatment with RA or SP600125 in LFs exposed to room air （P0.05）, but decreased remarkably after hyperoxia （P0.01 or 0.05）. SB203580 inhibited the expression of pro- and active MMP-2 either in room air or under hyperoxia （P0.01）. PD98059 exerted no effect on the expression of pro- and active MMP-2 （P0.05）. It was suggested that RA had a protective effect on hyperoxia-induced lung injury by down-regulating the expression of MMP-2 through decreasing the JNK and p38 activation in hyperoxia.

Intratracheal administration of umbilical cord-derived mesenchymal stem cells attenuates hyperoxia-induced multi-organ injury via heme oxygenase-1 and JAK/STAT pathways

BACKGROUND Bronchopulmonary dysplasia(BPD)is not merely a chronic lung disease,but a systemic condition with multiple organs implications predominantly associated with hyperoxia exposure.Despite advances in current management strategies,limited progress has been made in reducing the BPD-related systemic damage.Meanwhile,although the protective effects of human umbilical cord-derived mesenchymal stem cells(hUC-MSCs)or their exosomes on hyperoxia-induced lung injury have been explored by many researchers,the underlying mechanism has not been addressed in detail,and few studies have focused on the therapeutic effect on systemic multiple organ injury.AIM To investigate whether hUC-MSC intratracheal administration could attenuate hyperoxia-induced lung,heart,and kidney injuries and the underlying regulatory mechanisms.METHODS Neonatal rats were exposed to hyperoxia(80%O_(2)),treated with hUC-MSCs intratracheal(iT)or intraperitoneal(iP)on postnatal day 7,and harvested on postnatal day 21.The tissue sections of the lung,heart,and kidney were analyzed morphometrically.Protein contents of the bronchoalveolar lavage fluid(BALF),myeloper oxidase(MPO)expression,and malondialdehyde(MDA)levels were examined.Pulmonary inflammatory cytokines were measured via enzyme-linked immunosorbent assay.A comparative transcriptomic analysis of differentially expressed genes(DEGs)in lung tissue was conducted via RNA-sequencing.Subsequently,we performed reverse transcription-quantitative polymerase chain reaction and western blot analysis to explore the expression of target mRNA and proteins related to inflammatory and oxidative responses.RESULTS iT hUC-MSCs administration improved pulmonary alveolarization and angiogenesis(P<0.01,P<0.01,P<0.001,and P<0.05 for mean linear intercept,septal counts,vascular medial thickness index,and microvessel density respectively).Meanwhile,treatment with hUC-MSCs iT ameliorated right ventricular hypertrophy(for Fulton’s index,P<0.01),and relieved reduced nephrogenic zone width(P<0.01)and glomerular diameter(P<0.001)in kidneys.Among the beneficial effects,a reduction of BALF protein,MPO,and MDA was observed in hUC-MSCs groups(P<0.01,P<0.001,and P<0.05 respectively).Increased pro-inflammatory cytokines tumor necrosis factor-alpha,interleukin(IL)-1β,and IL-6 expression observed in the hyperoxia group were significantly attenuated by hUC-MSCs administration(P<0.01,P<0.001,and P<0.05 respectively).In addition,we observed an increase in anti-inflammatory cytokine IL-10 expression in rats that received hUC-MSCs iT compared with rats reared in hyperoxia(P<0.05).Transcriptomic analysis showed that the DEGs in lung tissues induced by hyperoxia were enriched in pathways related to inflammatory responses,epithelial cell proliferation,and vasculature development.hUC-MSCs administration blunted these hyperoxia-induced dysregulated genes and resulted in a shift in the gene expression pattern toward the normoxia group.hUC-MSCs increased heme oxygenase-1(HO-1),JAK2,and STAT3 expression,and their phosphorylation in the lung,heart,and kidney(P<0.05).Remarkably,no significant difference was observed between the iT and iP administration.CONCLUSION iT hUC-MSCs administration ameliorates hyperoxia-induced lung,heart,and kidney injuries by activating HO-1 expression and JAK/STAT signaling.The therapeutic benefits of local iT and iP administration are equivalent.

Effects of hypoxia,hyperoxia on the regulation of expression and activity of matrix metalloproteinase-2 in hepatic stellate cells

AIM: To study the effects of hypoxia, hyperoxia on the regulation of expression and activity of matrix metalloproteinase-2 (MMP-2) in hepatic stellate cells (HSC). METHODS: The expressions of MMP-2, tissue inhibitor of matrix metalloproteinase-2 (TIMP-2) and membrane type matrix metalloproteinase-1 (MT1-MMP) in cultured rat HSC were detected by immunocytochemistry (ICC) and in situ hybridization (ISH). The contents of MMP-2 and TIMP-2 in culture supernatant were detected with ELISA and the activity of MMP-2 in supernatant was revealed by zymography. RESULTS: In the situation of hypoxia for 12h, the expression of MMP-2 protein was enhanced (hypoxia group positive indexes: 5.7 +/- 2.0, n=10; control: 3.2 +/- 1.0, n = 7; P【0.05), while TIMP-2 protein was decreased in HSC (hypoxia group positive indexes: 2.5 +/- 0.7, n = 10; control: 3.6 +/- 1.0, n = 7; P 【 0.05), and the activity (total A) of MMP-2 in supernatant declined obviously (hypoxia group: 7.334 +/- 1.922, n = 9; control: 17.277 +/- 7.424, n = 11; P 【 0.01). Compared the varied duration of hypoxia, the changes of expressions including mRNA and protein level as well as activity of MMP-2 were most notable in 6h group. The highest value(A(hypoxia)-A(control)) of the protein and the most intense signal of mRNA were in the period of hypoxia for 6h, along with the lowest activity of MMP-2. In the situation of hyperoxia for 12h, the contents (A(450)) of MMP-2 and TIMP-2 in supernatant were both higher than those in the control, especially the TIMP-2 (hyperoxia group: 0.0499 +/- 0.0144, n = 16; control: 0.0219 +/- 0.0098, n = 14; P 【 0.01), and so was the activity of MMP-2 (hyperoxia group: 5.252 +/- 0.771, n = 14; control: 4.304 +/- 1.083, n = 12; P 【 0.05), and the expression of MT1-MMP was increased. CONCLUSION: HSC is sensitive to the oxygen, hypoxia enhances the expression of MMP-2 and the effect is more marked at the early stage; hyperoxia mainly raises the activity of MMP-2.

Effects of Hyperoxia on Mitochondrial Multienzyme Complex Ⅲ and Ⅴ in Premature Newborn Rat Lung

To investigate the effects of hyperoxia on mitochondrial multienzyme complex Ⅲ （cytochrome, Cytb） and Ⅴ （ATPase6, 8） in premature newborn rat lung, the 1-day-old preterm SD rats were randomly assigned to hyperoxia group and air group, The rats in hyperoxia group were continuously exposed to 85% oxygen and those in air group to room air. After 1, 4, 7, 10, 14 day（s） of exposure, these rats were killed, total lung RNA was extracted and Cytb, ATPase6, 8 mRNA were detected by reverse transcription polymerase chain reaction （RT-PCR）. Western blotting was used to detect the expression of Cytb protein in lung tissue. The results showed that compared with air group, Cytb mRNA expression was significantly increased （P〉0,05） after 1, 4 day（s） of exposure. The general tendency decreased after 7 days, and its expression became weak but difference in mRNA expression between the two groups was not significant （P〉0.05）. ATPase6 mRNA expression was significantly increased 1 day after the exposure （P〈0.05） and did not show any significant change 4, 7, 10 days after the exposure （P〉0.05）. At the 14th day, ATPase6 mRNA expression was significantly increased （P〈0.05）, ATPase8 mRNA expression did not show any significant change 1, 4, 10 day（s） after the exposure （P〉0.05）, At the 7th and 14th day, ATPase8 mRNA expression was significantly increased （P〈0.05）. Western blotting showed that Cytb protein expression was increased 1,4 day（s） after the exposure, but the difference between the two groups was not significant （P〉0.05）. The general tendency was decreased after 7 days, and its expression became weak but difference was not significant 7, 10 days after the exposure （P〉0.05）. At day 14 its expression became significantly weak （P〈0.05）. We are led to conclude that exposure to high concentrations of oxygen can significantly change the expression of Cytb and ATPase6, 8, which results in uncoupling of oxidative phosphorylation in mitochondrial respiration chain, and plays an important role in the mechanism of hyperoxia-induced lung injury.

N-methyl-D-aspartate receptor subtype 3A promotes apoptosis in developing mouse brain exposed to hyperoxia

In the present study, 7 day postnatal C57/BL6 wild-type mice （hyperoxia group） and 7 day postnatal N-methyI-D-aspartate receptor subtype 3A knockout mice （NR3A KO group） were exposed to 75% oxygen and 15% nitrogen in a closed container for 5 days. Wild-type mice raised in normoxia served as controls. TdT-mediated dUTP nick end labeling （TUNEL）/neuron-specific nuclear protein （NeuN） and 5-bromo-2＇-deoxyuridine （BrdU）/NeuN immunofluorescence staining showed that the number of apoptotic cells and the number of proliferative cells in the dentate subgranular zone significantly increased in the hyperoxia group compared with the control group. However, in the same hyperoxia environment, the number of apoptotic cells and the number of proliferative cells significantly decreased in the NR3A KO group compared with hyperoxia group. TUNEL＋/NeuN＋ and BrdU＋/NeuN~ cells were observed in the NR3A KO and the hyperoxia groups. These results demonstrated that the NR3A gene can promote cell apoptosis and mediate the potential damage in the developing brain induced by exposure to non-physiologically high concentrations of oxygen.

Effects of Hyperoxia on Cytoplasmic Thioredoxin System in Alveolar Type Epithelial Cells of Premature Rats

This study investigated the effects of hyperoxia on dynamic changes of thioredoxin-1 （Trx1） and thioredoxin reductase-1 （TrxR1） in alveolar type Ⅱ epithelial cells （AECⅡ） of premature rats. Pregnant Sprague-Dawley rats were sacrificed on day 19 of gestation. AECⅡ were isolated and purified from the lungs of premature rats. When cultured to 80% confluence, in vitro cells were randomly divided into air group and hyperoxia group. Cells in the hyperoxia group were continuously exposed to 95% O2/5% CO2 and those in the air group to 95% air/5% CO2. After 12, 24 and 48 h, cells in the two groups were harvested to detect their reactive oxygen species （ROS）, apoptosis, TrxR1 activity and the expressions of Trx1 and TrxR1 by corresponding protocols, respectively. The results showed that AECⅡ exposed to hyperoxia generated excessive ROS and the apoptosis percentage in the hyperoxia group was increased significantly at each time points as compared with that in the air group （P0.001）. Moreover, TrxR1 activity was found to be markedly depressed in the hyperoxia group in comparison to that in the air group （P0.001）. RT-PCR showed the expressions of both Trx1 and TrxR1 mRNA were significantly increased in AECⅡ exposed to hyperoxia for 12 and 24 h （P0.01）, respectively. At 48 h, the level of Trx1 mRNA as well as that of TrxR1 mRNA in the hyperoxia group was reduced and showed no significant difference from that in the air group （P0.05）. Western blotting showed the changes of Trx1 protein expressions in the hyperoxia group paralleled those of Trx1 mRNA expressions revealed by RT-PCR. It was concluded that hyperoxia can up-regulate the protective Trx1/TrxR1 expressed by AECⅡ in a certain period, however, also cause dysfunction of the cytoplasmic thioredoxin system by decreasing TrxR1 activity, which may contribute to the progression of oxidative stress and cell apoptosis and finally result in lung injury.