SB265610抗炎症干预在新生大鼠高氧肺损伤中的抗氧化作用

目的：探讨受体拮抗剂SB265610干预中性粒细胞（PMN）趋化作用后，高氧暴露新生大鼠肺部自由基产生情况。方法：采用600mL/LO2建立新生大鼠高氧暴露支气管肺发育不良模型（BPD）；新生大鼠随机分为4组：空气对照组，空气＋SB265610组，高氧对照组，高氧＋SB265610组；通过免疫组织化学和支气管肺泡灌洗液（BALF）细胞计数检测肺部中性粒细胞趋化因子、细胞因子诱导的中性粒细胞趋化因子-1（CINC-1）表达和炎性细胞聚集的情况；应用气相色谱-质谱（CC-MS）联用技术测定肺组织羟自由基；酶联免疫法测定脂质过氧化产物8-异前列腺烷。结果：高氧对照组新生大鼠肺内巨噬细胞、支气管和肺泡上皮细胞中CINC-1表达水平升高，同时WBC和PMN计数较空气对照组显著增加（Pa〈0．01）；高氧对照组新生大鼠肺中羟自由基水平显著高于空气对照组（P〈0．01），SB265610处理后高氧暴露鼠肺组织羟自由基水平明显下降（P〈0、01）；高氧对照组新生大鼠肺组织8-异前列腺烷水平显著升高，SB265610处理后明显降低（P〈0．01）。结论：抗PMN趋化干预可明显降低新生大鼠高氧肺损伤过程中肺内羟自由基及脂质过氧化水平。     

抗氧化剂在新生鼠高氧肺损伤治疗中的作用研究

目前,普遍认为:高氧肺损伤与氧自由基(oxygen free radical,OFR)的活性、炎性细胞的激活[1]以及细胞因子的释放有关.SOD抗氧化作用的安全性及疗效已得到了肯定[2].U74389G作为一种合成21-氨基类固醇的抗氧化剂,是甲基强的松龙提取物,没有激素活性,具有高亲脂性,易穿过细胞膜,是有效的铁离子螯合剂及有效的脂质过氧化物阻碍者.有报道[3],U74389G通过抑制高氧肺氧自由基、减轻炎症而减轻肺损伤,本研究观察了抗氧化剂U74389G及SOD对高氧暴露新生大鼠肺内组织氧自由基的产生、脂质过氧化物丙二醛(malondialdehyde,MDA)的产生、SOD的活性、肺的病理改变及对肺细胞凋亡的影响而阐述高氧肺损伤的机理,以探讨两者的抗氧化作用及两者的疗效比较.     

高浓度氧对新生鼠肺血红素加氧酶-1蛋白表达的影响

目的　探讨高浓度氧对新生鼠肺损伤及肺血红素加氧酶 1(HO 1)蛋白表达的影响。方法　将生后 4～ 7d新生SD大鼠 5 7只随机分为 0、2 4、4 8、72h空气对照组和 2 4、4 8、72h高氧暴露组 ,分别置于空气中和常压高氧舱 (氧浓度 92 %～ 94 % )中 ,后断头处死后取肺组织 ,对肺组织切片在光镜、电镜下进行病理组织学观察 ,对肺组织湿 /干重比值进行比较 ,采用免疫组织化学分析对HO 1蛋白表达进行半定量及定位分析。结果　高氧组与空气对照组比较 ,肺组织有明显水肿、出血和炎症 ,电镜下观察病变主要在毛细血管内皮细胞 ;高氧 72h组肺组织湿 /干重比值 (7.97± 1.18)较 72h空气对照组 (6 .4 0± 0 .37)明显升高 (P <0 .0 5 ) ;高氧 72h组肺组织HO 1蛋白表达 (0 .5 0 4± 0 .0 6 2 )较 72h空气对照组 (0 .345± 0 .0 2 4 )明显升高 (P <0 .0 1) ;高氧暴露组HO 1蛋白呈强阳性表达 ,主要分布在支气管、肺泡上皮细胞和肺泡巨噬细胞。结论　高浓度氧可引起新生鼠肺损伤 ,且高浓度氧可引起新生鼠肺HO 1蛋白表达上调 ,证明HO 1参与新生鼠高氧肺损伤的病理生理过程     

新生大鼠内毒素性急性肺损伤肺组织MDA、SOD和IL-10、IL-18的改变

目的探讨氧化/抗氧化及细胞因子在新生大鼠急性肺损伤中的变化.方法用脂多糖(LPS)制备新生大鼠急性损伤模型,用化学方法和酶联免疫吸附法(ELISA)分别检测肺组织丙二醛(MDA)、超氧化物歧化酶(SOD)、白细胞介素-10(IL-10)和白细胞介素-18(IL-18)的改变.结果MDA在应用LPS后1小时明显高于正常对照组,(31.99±1.73)nmol/mg肺蛋白VS(10.68±O.67)nmol/mg肺蛋白,持续至24小时;SOD含量在应用LPS后1小时即明显低于正常对照组,(69.86±2.94)NU/mg肺蛋白VS(85.99±1.89)NU/mg肺蛋白,4小时最低(58.61±3.01)NU/mg肺蛋白,8小时有所恢复,16小时基本正常;IL-10在注射LPS后4小时明显升高[(9.46±0.53)pg/mg肺蛋白],持续至16小时仍高于正常对照组(8.57±0.38)pg/mg肺蛋白,24小时下降至正常;IL-18在应用LPS后1小时即明显增多(10.73±0.29)pg/mg肺蛋白,持续至24小时.结论在LPS造成的新生大鼠急性肺损伤中,存在明显的氧化/抗氧化平衡失调,并有抑炎性和促炎症介质的失调,炎症介质释放的失调和氧化/抗氧化的失衡可能相互协同,加重肺损伤.     

高氧对新生大鼠肺caspase-3和p53基因表达及肺细胞凋亡的影响

目的探讨高氧对新生大鼠肺caspase3和p53基因表达及肺细胞凋亡的影响。方法采用SpraqueDawley新生大鼠95%氧气暴露建立高氧肺损伤模型。应用RTPCR技术检测肺组织caspase3mRNA和p53mRNA水平,凝胶电泳条带用成像系统照相分析结果。计算目的基因PCR产物条带与内参照βactin条带光密度值的比值,作为p53基因的相对表达量,结果以x±s标记,而caspase3mRNA表达量则以阳性表达或阴性表达为标记。应用脱氧核糖核酸转移酶介导的细胞凋亡标记技术(TUNEL)原位检测细胞凋亡。光镜下随机计算5个视野中500个肺细胞中的阳性细胞数,结果以x±s标记。结果新生大鼠暴露于95%氧浓度环境中24h后肺组织中p53mRNA表达中度增加(q=3.2305,P>0.05),48h后表达显著增加,与空气对照组相比差异有统计学意义(q=7.2941,P<0.05)。新生鼠高氧处理72h、96h后,肺组织p53mRNA表达又恢复到正常水平。在各空气对照组和各高氧处理组中个别新生鼠肺的caspase3mRNA有微量表达,绝大多数新生鼠肺的caspase3mRNA没有表达,差异无统计学意义。95%氧暴露7天的新生鼠肺细胞凋亡水平明显高于空气暴露组新生鼠肺细胞凋亡水平,两者比较差异有极显著的统计学意义(F=100,P<0.001)。结论在高浓度供氧下,肺组织通过暂时上调p53基因的表达,介导细胞周期停滞,阻止G0/G1期细胞进入S期,抑制细胞分裂、增殖,同时p53促进细胞凋亡,从而导致肺生长发育受阻和肺损伤。新生鼠暴露于95%氧环境中,肺组织caspase3基因基本上不表达,因此推测高氧肺细胞凋亡可能存在不经过caspase3的凋亡途径。     

机械通气在不同条件下对新生兔肺损伤及MMP-2表达的影响

目的 观察基质金属蛋白酶MMP-2在新生兔机械通气肺损伤中的表达和变化规律,研究肺损伤的分子机制.方法 将108只新生兔随机分配在高浓度氧、低浓度氧组,每组又分为高吸气峰压、中吸气峰压、低吸气峰压共6组进行机械通气并与正常未通气组6只进行对照,通气后1、3、6 h 3个时间点活杀取肺,病理切片MMP-2免疫组织化学染色,ELISA法检测肺组织匀浆中MMP-2的浓度,RT-PCR检测肺组织MMP-2mRNA的表达.结果 机械通气时,不同浓度的氧能使MMP-2表达上调,高浓度氧组为(5.38±1.57) μg/ml、低浓度氧组为(4.83±1.46) μg/ml,两组间差异无统计学意义,但同对照组(4.36±0.51) μg/ml相比,高氧组差异有统计学意义(F=3.658,P＜0.05).不同的机械拉伸力能使MMP-2上调,高、中、低压力3组分别为(5.10±1.79)、(5.35±1.38)、(4.96±1.49) μg/ml,3组间差异无统计学意义,但同对照组比,中压力组差异有统计学意义(F=2.764,P＜0.05).MMP-2同肺组织湿干比弱相关,同灌洗液细胞总数、细胞分类、肺损伤评分间统计学不相关.结论 新生兔机械通气6 h内,高浓度的氧通气能上调MMP-2,适中机械拉伸上调MMP-2,MMP-2同肺损伤有较少的相关性.     

TGFβ1在高氧暴露致肺纤维化早产大鼠肺组织不同细胞表达的定量研究

探讨转化生长因子β1(TGFβ1)与高氧暴露致肺纤维化发生、发展的关系及其在肺组织的细胞来源,应用免疫组化法结合图象分析处理系统定量研究TGFβ1在高氧暴露致肺纤维化早产大鼠肺组织不同细胞中的免疫反应.结果显示TGFβ1可广泛分布于空气对照组早产大鼠肺组织,而在高氧组中表达明显增加.其中,肺泡巨噬细胞的表达在第7 d天达高峰(71.82±15.39),而第14 d支气管肺泡上皮、肺间质细胞的表达分布最广,阳性表达面积比分别为(46.47±9.65)和(54.39±12.35),此时肺组织羟脯氨酸含量明显增加[(2.08±0.12)mg.g肺-1].结论TGFβ1在高氧暴露致肺纤维化早产大鼠肺组织中具有重要作用,肺泡巨噬细胞TGFβ1的大量表达与肺纤维化的早期密切相关,而支气管肺泡上皮、肺间质细胞表达的进一步增强则在纤维化的持续进展中发挥了一定作用.     

TGFβ_1在高氧暴露致肺纤维化早产大鼠肺组织不同细胞表达的定量研究

探讨转化生长因子β1(TGFβ1)与高氧暴露致肺纤维化发生、发展的关系及其在肺组织的细胞来源,应用免疫组化法结合图象分析处理系统定量研究TGFβ1在高氧暴露致肺纤维化早产大鼠肺组织不同细胞中的免疫反应。结果显示:TGFβ1可广泛分布于空气对照组早产大鼠肺组织,而在高氧组中表达明显增加。其中,肺泡巨噬细胞的表达在第7 d天达高峰(71.82±15.39),而第14 d支气管肺泡上皮、肺间质细胞的表达分布最广,阳性表达面积比分别为(46.47±9.65)和(54.39±12.35),此时肺组织羟脯氨酸含量明显增加[(2.08±O.12)mg.g肺-1]。结论:TGFβ1在高氧暴露致肺纤维化早产大鼠肺组织中具有重要作用,肺泡巨噬细胞TGFβ1的大量表达与肺纤维化的早期密切相关,而支气管肺泡上皮、肺间质细胞表达的进一步增强则在纤维化的持续进展中发挥了一定作用。     

高氧致新生大鼠支气管肺发育不良肺成肌纤维细胞分布的变化及意义

目的 观察高氧致新生大鼠支气管肺发育不良(BPD)肺组织α-平滑肌肌动蛋白(α-SMA)表达及胶原的变化,探讨高氧致新生大鼠BPD的发生与成肌纤维细胞的内在联系.方法 将新生大鼠持续暴露在85%高氧环境中,在实验的1、3、7、14、21 d,取左肺组织固定、脱水、石蜡包埋、切片,用于肺组织病理变化观察及α-SMA表达的免疫组织化学检测;右肺-80℃冰冻,用于Ⅰ型胶原(ColⅠ)蛋白和mRNA表达检测.结果 新生大鼠长期高氧暴露可致肺泡简单化,肺泡数目减少,终末气腔扩张,次级隔数目减少,肺泡间隔显著增厚,出现纤维化.高氧暴露14和21 d时,α-SMA在肺泡间隔和肺泡表面表达显著增强,呈条素状分布;但空气组仅在次级间隔的顶端呈点状分布.随高氧暴露时间延长,Col Ⅰ表达增加,并且高氧组肺组织α-SMA表达与Col Ⅰ mRNA表达呈明显正相关(r=0.59,P< 0.05).结论 新生大鼠高氧暴露导致肺损伤符合早产儿BPD的病理改变,成肌纤维细胞分布紊乱可能在BPD的发病过程中起重要作用.     

细胞粘附因子-1在新生大鼠高氧肺损伤模型肺组织的表达及意义

目的探讨细胞粘附因子-1(ICAM-1)与新生大鼠高氧肺损伤的关系以及高氧肺损伤的发病机制。方法取102只胎龄22天足月新生大鼠,随机分为实验组与对照组各51只。实验组生后立即置入持续高浓度氧(>95%)环境中饲养,对照组在空气中饲养。两组新生大鼠根据随机数字法于生后第3、7、14天各抽取8只定位相应亚组。处死新生鼠取其肺组织,HE染色观察肺组织病理变化,Masson三色染色判断肺组织纤维化程度,免疫组化检测ICAM-1并对表达强度进行半定量分析。结果 (1)对照组生后3、7、14天各亚组未见肺损伤的病理性改变,Masson三色染色未见胶原沉积增多现象,ICAM-1在肺组织中阴性或弱阳性表达。(2)实验组7天HE染色可见大量炎细胞浸润,肺间隔轻度增宽,14天炎细胞浸润减少,肺泡结构破坏较明显,肺间隔明显增厚;Masson三色染色生后7天胶原沉积开始增加,14天纤维化程度更加显著,ICAM-1在各时间点均呈阳性表达,且分布广泛;半定量分析显示,实验组各时间点ICAM-1的表达明显高于对照组,生后7天表达最强(P<0.05)。结论高氧对肺组织有明显的损害作用,高氧暴露早期ICAM-1在肺组织中的表达随着暴露时间的延长而增加,ICAM-1在高氧暴露早期的急性炎症阶段起作用,继续暴露则逐渐降低,并未证实其与高氧肺损伤后期的纤维化有关系。     

促红细胞生成素对新生大鼠高氧肺损伤细胞凋亡的影响

目的：探讨人重组促红细胞生成素（rhEPO）对新生大鼠高氧肺损伤细胞凋亡的影响。方法：96只新生Sprague-Dawley大鼠随机分为4组：空气+生理盐水（NS）组,空气+rhEPO组,高氧+NS组,高氧+rhEPO组。后两组暴露于95%氧气中,高氧+rhEPO组于高氧暴露后2 d、4 d、6 d给予rhEPO 800 U /kg皮下注射, 空气+rhEPO组于同样时间点给予等量rhEPO。各组氧暴露后第3、7、14天随机抽取8只大鼠处死并取肺组织,苏木精-伊红染色观察病理变化,蛋白印迹法测定p-JNK水平,TUNEL法测定细胞凋亡。结果：与空气+NS组比较,高氧+NS组3 d出现肺泡炎性反应渗出,7 d更为明显,14 d出现肺泡数量减少,大小不均,肺大泡形成,高氧+rhEPO组的病理改变减轻,炎性反应细胞浸润减少。高氧+rhEPO组肺组织p-JNK水平较高氧+NS组有所减少,细胞凋亡减轻。结论：促红细胞生成素能通过减少细胞凋亡对新生大鼠高氧肺损伤起保护作用,其作用可能是通过JNK途径所介导。［中国当代儿科杂志,2010,12（7）：576-579］     

Endothelin-1 and O2-mediated pulmonary hypertension in neonatal rats: a role for products of lipid peroxidation

We hypothesized that reactive O2 species, or their intermediary products, generated during exposure to elevated O2 lead to pathologic endothelin-1 expression in the newborn lung. Endothelin-1 expression and 8-isoprostane content (an in vivo marker of lipid peroxidation) were examined and found to be elevated (p < 0.05) in the lungs of newborn rats with abnormal lung morphology and pulmonary hypertension, as assessed by right ventricular hypertrophy, after a 14-d exposure to 60% O2. The antioxidant and lipid hydroperoxide scavenger, U74389G (10 mg/kg), given by daily i.p. injection prevented O2-dependent right ventricular hypertrophy (p < 0.05 compared with vehicle-treated controls), but had no effect on abnormal lung morphology. Additionally, we observed that 8-isoprostane caused marked endothelin-1 mRNA up-regulation in vitro in primary rat fetal lung cell cultures. We conclude that reactive O2 species, or their bioactive intermediaries, are causative in O2-mediated pulmonary hypertension and endothelin-1 up-regulation. It is likely that the bioactive lipid peroxidation product, 8-isoprostane, plays a key role in pathologic endothelin-1 expression and pulmonary hypertension during oxidant stress.     

Effect of the 21-aminosteroid U74389G on oxygen-induced free radical production, lipid peroxidation, and inhibition of lung growth in neonatal rats.

Bronchopulmonary dysplasia is a chronic pneumopathy of preterm infants, with significant associated mortality and morbidity, for which there is no effective preventive therapy. Pulmonary O2 toxicity is thought to be a major contributor to the development of bronchopulmonary dysplasia, and antioxidant interventions hold significant promise for therapy. The relative importance of specific reactive oxygen species in the development of O2-mediated lung injury is unknown. In this study, we tested the effect of a synthetic 21-aminosteroid, U74389G, on 95% O2-induced free radical production, lipid peroxidation, and inhibition of postnatal lung growth in a neonatal rat model. Lipid peroxidation products, as measured by total 8-isoprostane and aldehydes, and hydroxyl radical formation, assessed using salicylate metabolites, in rat lungs and serum were significantly increased after exposure to 95% O2. These changes could be completely or partially attenuated by U74389G. However, U74389G did not improve the survival rate or lung wet-to-dry weight ratio. Expression of proliferating cell nuclear antigen, a marker for DNA synthesis, was examined by immunohistochemistry. Four- or 7-d-old control rat lungs had active DNA synthesis, which was inhibited by exposure to 95% O2. U74389G had a protective effect against 95% O2-mediated inhibition of DNA synthesis. Air-exposed animals treated with U74389G had a modest reduction in lung DNA synthesis, consistent with a role for hydroxyl radicals or lipid hydroperoxides as second messengers in the normal regulation of lung growth.     

吸入高浓度氧对大鼠肺泡发育过程促红细胞生成素受体的影响

目的 探讨大鼠肺泡发育阶段促红细胞生成素受体(erythropoietin receptor,EPOR)的动态变化以及吸入高浓度氧对EPOR的影响.方法 将48只新生Wistar大鼠生后12 h内随机分为空气组和高氧组.高氧组将动物置于自制密闭氧箱中,持续输入氧气,FiO2=0.85±0.02.在实验3,7和14 d每组随机选取8只处死,采集标本.采用HE染色观察肺组织病理改变,放射状肺泡计数评价肺泡化程度,免疫组织化学法检测肺组织血小板内皮细胞黏附分子-1(platelet endothelial cell adhesion molecule-1,PECAM-1)及EPOR表达,PT-PCR及Western blot法检测肺组织EPOR基因和蛋白表达.结果 高氧组3 d时肺毛细血管扩张、充血,7 d时肺泡体积增大、数量减少,14 d时肺泡数量及毛细血管进一步减少.空气组RAC值随日龄增长而增加,与空气组相比,高氧组7 d时RAC值降低[(6.85±104):(7.33±1.0),P＜0.01],差异在14 d更显著[(6.20±1.58):(9.07±0.69),P＜0.001].空气组PECAM-1表达随日龄增长逐渐增强,高氧组7 d和14 d PECAM-1表达较空气组明显减弱[(15.14±1.51):(31.47±2.43),(11.04±1.76):(41.41±3.83),P＜0.001].空气组EPOR染色在生后3 d最强,随日龄增长逐渐减弱,与空气组相比,高氧组各时点EPOR表达均明显减弱[(1.62±0.04):(1.82±0.06),P＜0.05;(0.48±0.01):(1.10±0.07),(0.39±0.04):(0.87±0.03),P＜0.001].空气组EPOR mRNA表达在生后3 d最强,高氧组各时点EPOR mRNA表达较空气组明显减弱[(0.87±0.07):(1.1±0.17),(0.18±0.07):(0.36±0.08),P＜0.01;(0.14±0.05):(0.36±0.09),P＜0.001].结论 EPOR可能在正常肺泡发育过程发挥调节作用,吸入高浓度氧导致的肺泡及血管发育阻滞可能与EPOR及PECAM-1蛋白表达减弱有关.

Abstract：

Objective Oxygen toxicity is thought to be a major contributing factor in the pathogenesis ofbronchopulmonary dysplasia (BPD). Animal experiments reveal that erythropoietin (EPO) may have protective effects against hyperoxic lung injury, but the mechanisms remain unknown.The aim of this study was to evaluate effects of hyperoxia on erythropoietin receptor expression in lung development of neonatal rats.Methods Several litters of Wistar pups were pooled together within 12 hours after birth and randomly divided into two groups (n = 24 in each ): air-exposed control group and hyperoxia-exposed group. In hyperoxia-exposed group, the rats were exposed to 85% oxygen. Pups ( n = 8 ) from each group were sacrificed on postnatal days 3, 7, and 14.The pulmonary histologcal and morphometric changes were observed after hematoxylin-eosin (HE) staining under light microscope. Radical alveolar counts ( RAC )were compared between the two groups to evaluate the differences of aveolarization. Expressions of platelet endothelial cell adhesion molecule-1 ( PECAM-1 ) and erythropoietin receptor (EPOR) in lung tissue were measured by immunohistochemistry.Expressions of EPOR mRNA and EPOR protein were measured by RTPCR and Western blotting. Results In hyperoxia-exposed group, there were a few inflammatory cells infiltration in interstitium on day 3 and inflammatory response worsened on day 7. Alveolar and capillary hypoplasia and interstitial fibrosis were evident on day 14.RAC increased in air-exposed control group along with the age in days. RAC decreased from day 7 in hyperoxia-exposed group compared with air-exposed control group [( 6.85 ± 1.04 ) vs.( 7.33 ± 1.0 ), P ＜ 0.01], which was more evident on day 14 [( 6.20 ±1.58 ) vs.(9.07 ± 0.69 ), P ＜ 0.001].Expression of PECAM-1 protein increased in air-exposed control group along with the age in days.But in hyperoxia-exposed group, it decreased on day 7 and 14 [( 15.14 ±1.51) vs.(31.47 ±2.43),(11.04 ± 1.76)vs.(41.41 ±3.83),P＜0.001]compared with air-exposed control group.Expression of EPOR on day 3 in air-exposed control group was the strongest and weakened gradually with the increase of postnatal days.Expression of EPOR in hyperoxia-exposed group decreased on day 3 and became more evident on day 7 and day 14 compared with air-exposed control group [( 1.62 ±0.04) vs.(1.82±0.06), P＜0.05;(0.48 ±0.01)vs.(1.10±0.07), (0.39±0.04) vs.(0.87±0.03 ) ,P ＜0.001].Expression of EPOR mRNA on day 3 in air-exposed control group was the strongest and was decreased significantly in hyperoxia-exposed group compared with air-exposed control group at all time points [(0.87±0.07)vs.(1.1±0.17),(0.18±0.07)vs.(0.36±0.08),P＜0.01;(0.14±0.05)vs.(0.36 ± 0.09 ), P ＜ 0.001]. Conclusions EPOR may participate in the modulation of normal lung development.Depressed expression of EPOR and PECAM-1 may be involved in the pathogenesis of alveolar and capillary hypoplasia induced by hyperoxia.     

Up-regulation of connective tissue growth factor in hyperoxia-induced lung fibrosis

Pulmonary oxygen toxicity plays an important role in the lung injury process that leads to the development of bronchopulmonary dysplasia. Connective tissue growth factor (CTGF) is a fibroblast mitogen and promoter of collagen deposition. We investigated the effects of postnatal hyperoxia on lung collagen and CTGF expression in rats. Rat pups were exposed to 7 d of >95% O2 and a further 3 wk of 60% O2. CTGF mRNA and protein expression increased after hyperoxia treatment, and the values were significantly higher in hyperoxia-exposed rats on postnatal d 7 and 14. Lung collagen levels increased as rats aged, and the values were comparable between room air-exposed and hyperoxia-exposed rats on postnatal d 7 and 14 and were significantly higher in hyperoxia-exposed rats on postnatal d 21 and 28. Increases in CTGF mRNA and protein expressions preceded the onset of increased lung collagen. These data demonstrate that CTGF is up-regulated at time points preceding the fibrotic phase of the lung injury adding credence to the hypothesis that CTGF seems to be involved in the pathogenesis of hyperoxia-induced lung fibrosis and an anti-CTGF strategy might attenuate hyperoxia-induced lung fibrosis.     

Effects of erythropoietin on hyperoxic lung injury in neonatal rats

Pulmonary oxygen toxicity is believed to play a prominent role in the lung injury that leads to the development of bronchopulmonary dysplasia (BPD). To determine whether human recombinant erythropoietin (rhEPO) treatment reduces the risk of developing BPD, we investigated the effect of rhEPO treatment on the histopathologic changes seen in hyperoxia-induced lung injury of BPD. Twenty-five rat pups were divided into four groups: air-exposed control group (n = 5), hyperoxia-exposed placebo group (n = 7), hyperoxia-exposed rhEPO-treated group (n = 6), and air-exposed rhEPO-treated group (n = 7). Measurement of alveolar surface area, quantification of secondary crest formation, microvessel count, evaluation of alveolar septal fibrosis, and smooth muscle actin immunostaining were performed to assess hyperoxia-induced changes in lung morphology. Treatment of hyperoxia-exposed animals with rhEPO resulted in a significant increase in the mean alveolar area, number of secondary crests formed, and the microvessel count in comparison with hyperoxia-exposed placebo-treated animals. There was significantly less fibrosis in rhEPO-treated animals. However, treatment of hyperoxia-exposed animals with rhEPO did not result in a significant change in smooth muscle content compared with hyperoxia-exposed placebo treated animals. Our results suggest treatment with rhEPO during hyperoxia exposure is associated with improved alveolar structure, enhanced vascularity, and decreased fibrosis. Therefore, we conclude that treatment of preterm infants with EPO might reduce the risk of developing BPD.     

褪黑素对高氧致新生鼠慢性肺疾病肺组织氧化/抗氧化系统的影响

目的：探讨近年来发现的高效抗氧化剂褪黑素（MT）对高氧致新生鼠慢性肺疾病（CLD）肺组织氧化/抗氧化系统的影响。方法：采用高氧暴露（FiO2＝0.85）致新生鼠CLD模型,足月新生鼠共90只随机分为3组（每组30只）：空气对照组、高氧对照组、MT治疗组。空气对照组置于空气中,高氧对照组、MT治疗组（连同母鼠）置于玻璃氧箱中,维持FiO2为0.85;MT治疗组于生后0 d高氧暴露前30 min和生后每天给予MT 4 mg/kg腹腔注射直至实验结束。每组分别于实验后3,7,14 d随机选取10只处死,观察肺组织形态改变,分别测定肺组织中总抗氧化能力（T-AOC）、超氧化物歧化酶（SOD）、谷胱苷肽过氧化物酶（GSH-Px）活性、髓过氧化物酶（MPO）、过氧化氢酶（CAT）、NO水平（以NO2-/NO3-衡量）以及丙二醛（MDA）含量改变。结果：MT治疗组病理改变明显减轻。空气对照组、高氧对照组、MT治疗组T-AOC,SOD,GSH-Px及CAT活性随实验时间的延长均逐渐升高,但空气对照组、高氧对照组两组比较各项指标差异均无显著性（P>0.05）,MT治疗组各项指标在实验各时点与空气对照组、高氧对照组相比均明显升高（P<0.05）。高氧对照组NO2-/NO3-,MDA水平以及MPO含量在3,7,14 d均高于空气对照组（P<0.05或0.01）。MT治疗组NO2-/NO3-,MDA水平以及MPO含量则明显降低,与高氧对照组比较差异具有显著性（P<0.05）。结论：MT通过提高肺组织的抗氧化能力、抑制氧化应激反应,从而逆转了高氧致新生鼠CLD肺组织氧化/抗氧化系统失衡。［中国当代儿科杂志,2009,11（7）：581-584］     

The effect of inhaled nitric oxide and oxygen on the hydroxylation of salicylate in rat lungs

Inhaled nitric oxide (iNO) is used as a selective pulmonary vasodilator, and often under conditions when a high fraction of inspired oxygen is indicated. However, little is known about the potential toxicity of iNO therapy with or without concomitant oxygen therapy. NO can combine with superoxide (O2-) to form peroxynitrite (ONOO-), which can in turn decompose to form hydroxyl radical (OH.). Both OH. and ONOO- are involved in various forms of lung injury. To begin evaluation of the effect of iNO under either normoxic or hyperoxic conditions on OH. and/or ONOO- formation, rats were exposed for 58 h to either 21% O2, 21% O2 + 10 parts per million (ppm) NO, 21% O2 + 100 ppm NO, 50% O2, 90% O2, 90% O2 + 10 ppm NO, or 90% O2 + 100 ppm NO. We used a salicylate hydroxylation assay to detect the effects of these exposures on lung OH. and/or ONOO- formation measured as the appearance of 2,3-dihydroxybenzoic acid (2,3-DHBA). Exposure to 90% O2 and 90% O2 + 100 ppm NO resulted in significantly (p < 0.05) greater lung wet weight (1.99 +/- 0.14 g and 3.14 +/- 0.30 g, respectively) compared with 21% O2 (1.23 +/- 0.01 g). Exposure to 21% O2 + 100 ppm NO led to 2.5 times the control (21% O2 alone) 2,3 DHBA formation (p < 0.05) and exposure to 90% O2 led to 2.4 times the control 2,3-DHBA formation (p < 0.05). However, with exposure to both 90% O2 and 100 ppm NO, the 2,3-DHBA formation was no greater than the control condition (21% O2). Thus, these results indicate that, individually, both the hyperoxia and the 100 ppm NO led to greater salicylate hydroxylation, but that the combination of hyperoxia and 100 ppm NO led to less salicylate hydroxylation than either did individually. The production of OH. and/or ONOO- in the lung during iNO therapy may depend on the ratio of NO to O2.     

Melatonin protects against oxidative damage in a neonatal rat model of bronchopulmonary dysplasia

Background  Oxidative stress plays an important role in the pathogenesis of bronchopulmonary dysplasia (BPD). Melatonin (MT) has direct and indirect free radical detoxifying activity. The present study was to investigate whether treatment with MT would attenuate hyperoxia-induced lung injury and the effect of MT on imbalance of oxidants/antioxidants in the lung of neonatal rats. Methods  BPD was induced by exposure to hyperoxia in neonatal rats (n=90). The rats were divided randomly into three groups (n=30 each): air-exposed control group, hyperoxia-exposed group, and hyperoxia-exposed MT-treated group. Lung specimens were obtained respectively on day 3, day 7, and day 14 after exposure (n=10 each). Activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT), and levels of myeloperoxidase (MPO), nitrite/nitrate, and malondialdehyde (MDA) were assayed. Histopathologic changes were observed in the tissues stained with hematoxylin and eosin and Masson’s trichrome stain. Results  Increased levels of MPO, nitrite/nitrate, and MDA in the hyperoxia-exposed rats were significantly reduced by MT (P<0.05). Activities of GSH-Px, SOD, and CAT which did not change after exposure to hyperoxia were increased by MT (P<0.05). Furthermore, BPD associated histopathological alterations such as reduced total number of alveoli and interstitial fibrosis were obviously abated in the MT-treated group. Conclusions  MT can reverse oxidants/antioxidants imbalance in damaged lung tissue and thus exert a beneficial effect on hyperoxia-induced lung disease in neonatal rats. With regard to humans, there may be a protective effect of MT on BPD.