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.

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.

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.

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.

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.

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.

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.

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.

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 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.

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.

OPTICAL IMAGING OF LIPOPOLYSACCHARIDE-INDUCED OXIDATIVE STRESS IN ACUTE LUNG INJURY FROM HYPEROXIA AND SEPSIS

Reactive oxygen species(ROS)have been implicated in the pathogenesis of many acute and chronic pulmonary disorders such as acute lung injury(ALI)in adults and bronchopulmonary dysplasia(BPD)in premature infants.Bacterial infection and oxygen toxicity,which result in pulmonary vascular endot belial injury,contribute to impaired vascular growth and alveolar simplfcation soen in the lungs of premature infants with BPD.Hyperoxia induces ALI,reduces cell proliferation,cauuses DNA damage and promotes cell death by causi ng mitochondrial dys function.The objective of this study was to use an optical imaging technique to evaluate the variations in fluorescence intensities of the auto fuorescent mitochondrial metabolic coenzymes,NADH and FAD in four different groups of rats.The ratio of these fluorescence signals(NA DH/FAD),referred to as NADH redox ratio(NADH RR)has been used as an indicator of tisue metabolism in injuries.Here,we investigated whether the changes in metabolic state can be used as a marker of oxidative stress caused by hyperoxia and bacterial lipopolysaccharide(LPS)exposure in neonatal mat lungs.We examined the tissue redox states of lungs from four groups of rat pups:nomoxic(21%O_(2))pups,hyperoxic(90%O_(2))pups,pups treated with LPS(normoxic+LPS),and pups treated with LPS and hyperoxia(hyperoxic+LPS).Our results show that hyperoxia oxidized the respiratory chain as reflected by a~31%docrease in lung tssue NADH RR as compared to that for normoxic lungs.LPS treatment alone or with hyperoxia had no significant ffect on lung tssue NADH RR as compared to that for normoxic or hyperoxic lungs,respectively.Thus,NADH RR serves as a quantitative marker of oxidative stress level in lung injury caused by two clinically important conditions:hyperoxia and LPS exposure.

常压高浓度氧对新生大鼠脑微血管内皮细胞损伤与Nrf2/HO-1信号通路的影响分析

目的探究常压高浓度氧(NBO)对新生大鼠脑微血管内皮细胞损伤及核因子E2相关因子2/血红素氧合酶-1(Nrf2/HO-1)信号通路的影响。方法取新生SD大鼠45只,采用随机数字表法分为常氧组、NBO组和NBO+Nrf2激活剂组,每组各15只。常氧组大鼠置于普通空气(21%氧气)中饲养,NBO组和NBO+Nrf2激活剂组大鼠置于90%常压氧气饲养,NBO+Nrf2激活剂组每日灌胃5 mg/kg Nrf2激动剂莱菔硫烷。测定脑组织伊文思蓝(EB)含量,采用酶联免疫法检测血管内皮生长因子(VEGF)和基质金属蛋白酶9(MMP-9)含量,干湿重法检测脑组织含水量,HE染色和TUNEL染色观察脑组织病理变化,蛋白质印迹法检测海马组织Nrf2/HO-1信号通路蛋白表达,水迷宫检测大鼠认知功能。结果与常氧组比较,NBO组脑组织EB、VEGF、MMP-9含量及脑组织含水量升高,差异均有统计学意义(P<0.05);与NBO组比较,NBO+Nrf2激活剂组脑组织EB、VEGF、MMP-9含量及脑组织含水量降低,差异均有统计学意义(P<0.05)。病理染色结果显示,常氧组大鼠神经细胞形态及结构完整,未见明显病理变化和细胞凋亡;NBO组神经细胞形态及结构不规则,出现明显的水肿和空泡,并伴有大量的凋亡细胞;NBO+Nrf2激活剂组脑组织病理损伤较NBO组明显减轻。与常氧组比较,NBO组脑组织Nrf2、HO-1蛋白相对表达量降低,差异均有统计学意义(P<0.05);与NBO组比较,NBO+Nrf2激活剂组Nrf2、HO-1蛋白相对表达量升高,差异均有统计学意义(P<0.05)。与常氧组比较,NBO组第2~4天逃避潜伏期延长,穿越平台次数减少,差异均有统计学意义(P<0.05);与NBO组比较,NBO+Nrf2激活剂组第2~4天逃避潜伏期缩短,穿越平台次数增多,差异均有统计学意义(P<0.05)。结论NBO可诱导新生大鼠脑微血管内皮细胞损伤,导致远期认知功能障碍,可能与下调Nrf2/HO-1信号通路表达有关。

隐丹参酮通过调节TGF⁃β/Smad通路改善高氧诱导肺损伤的纤维化过程

目的:探讨隐丹参酮(cryptotanshinone,CTS)对高氧诱导的支气管肺发育不良(bronchopulmonary dysplasia,BPD)大鼠肺纤维化的影响及作用机制。方法:体内实验:将50只新生雄性SD大鼠随机分为空气组、高氧组、CTS低剂量组(7.5 mg/kg)、CTS中剂量组(15.0 mg/kg)及CTS高剂量组(30.0 mg/kg)。高氧组及CTS干预组大鼠饲养于氧浓度95%的氧箱中,空气组饲养于空气中。CTS干预组大鼠生后每日给予CTS腹腔注射,空气组及高氧组每日腹腔注射同等体积DMSO。7 d后安乐死全部大鼠后取肺组织用于后续实验。应用HE染色观察肺泡病理改变;通过Masson染色观察肺组织纤维化程度;RT⁃qPCR法检测转化生长因子β1(transforming growth factor⁃β1,TGF⁃β1)及α平滑肌肌动蛋白(α⁃smooth muscle actin,α⁃SMA)的mRNA水平;Western blot检测细胞信号转导分子(small mother against decapentaplegic,Smad)2/3、p⁃Smad2/3的表达。体外实验:选用人胚肺成纤维细胞(human fetal lung fibroblast⁃1,HFL⁃1),按照培养条件分为空气组、高氧组及CTS干预组,空气组常规条件下培养,而高氧及干预组置于95%O2恒温培养箱中培养24 h,干预组加入CTS 10μmol/L。CCK⁃8实验检测细胞活力;Western blot检测TGF⁃β1、α⁃SMA、p⁃Smad2/3、Smad2/3蛋白表达变化。结果:与对照组相比,高氧组大鼠肺泡形态紊乱、间隔增宽,RAC值下降,纤维化评分上升(P<0.05);TGF⁃β1及α⁃SMA的mRNA水平升高(P<0.05);p⁃Smad2/3表达升高(P<0.05);不同剂量的CTS给药后可改善上述指标(P<0.05);同时,CTS还可以降低高氧后HFL⁃1细胞的TGF⁃β1、α⁃SMA、p⁃Smad2/3、Smad2/3表达(P<0.05)。结论:CTS可通过TGF⁃β/Smad通路改善高氧诱导肺损伤的纤维化过程。

高流量氧疗与常规氧疗治疗急性心源性肺水肿的应用效果

目的探讨高氧流量和常规氧流量在急性心源性肺水肿中的应用效果。方法采用前瞻性随机对照性研究方法,选择2019年2月至2021年10月收治的62例急性心源性肺水肿合并低氧血症的患者,随机分成常规组32例和高流量氧疗组(HFNC组)30例,常规组给予常规氧疗,直至文氏面罩或鼻导管吸氧使FiO2达50%,目标保持SPO2为90%~96%。HFNC组采用Optiflow经鼻高流量加温加湿氧疗系统AIRVO 2型治疗设备进行高流量氧疗,吸气峰流速的高流量的加温(37℃)加湿(100%相对湿度)空氧混合气体,初始参数氧流量4~6 L/min(相当于FiO240%~50%),空氧混合气体流量60 L/min。根据目标SPO2每5分钟上调或下调HFNC 10%氧浓度。对比患者的呼吸参数和氧合指标以及患者舒适度情况。结果与常规组相比,氧疗后30 min、60 min,HFNC组的HR均降低(均P<0.01);同时HFNC组各时间点的SBP无明显变化(P>0.05);氧疗后60 min,HFNC组舒适性评分明显上升(P<0.01)。其他各参数24 h无创通气、24 h有创通气、7 d病死率组内与组间相比差异均无统计学意义(P>0.05)。结论高流量氧疗可以有效改善急性心源性肺水肿患者的低氧状态,与常规氧疗相比,改善缺氧状态更快、更显著,具有使用简单、快速、舒适性好等特点,值得推广使用。

吸入氢气对高氧诱导新生SD大鼠支气管肺发育不良(BPD)的影响

目的探讨吸入氢气对高氧诱导新生SD大鼠支气管肺发育不良(BPD)的影响。方法选取新生SD大鼠吸入85%高氧建立支气管肺发育不良模型。分为control组(正常空气)9只、BPD组(85%O_(2))13只、H_(2)组(2%H_(2))12只及Treat组(85%O_(2)+2%H_(2))16只,共4组。记录各组大鼠体重;14 d后取肺组织,采用苏木精-伊红(HE)染色法进行病理切片观察与评价;肺组织匀浆上清液检测肺损伤的标志物神经酰胺(Cer);取血,检测脑损伤标志物肌钙结合蛋白(S100B)、心肌损伤标志物心肌肌钙蛋白(cTnI)并进行比较。结果BPD组体重增长显著慢于control组,差异有统计学意义(F=7.122,<0.05)。HE染色结果显示高氧使肺泡简化,肺泡数量明显减少,吸入氢气可有效改善;4组肺泡平均截距比较,BPD组>Treat组肺泡>control组与H_(2)组,差异有统计学意义(F=24.951,P<0.05)。Cer水平BPD组>control组、H_(2)组与Treat组,cTnI水平BPD组>H_(2)组>Treat组>control组,S100B水平BPD组>Treat组>H_(2)组、control组,差异具有统计学意义(F=19.361、26.321、13.235,P<0.05)。结论吸入H_(2)可改善肺损伤,改善脑损伤与心肌损伤,其机制可能与抗氧化有关。