地塞米松抑制哮喘大鼠肺组织p38蛋白激酶的表达

目的:探讨支气管哮喘大鼠肺组织p38蛋白激酶(p38 MAPK)表达的变化以及地塞米松对其影响.方法:复制大鼠哮喘模型,随机分成3组:正常对照组、哮喘对照组和地塞米松(DEX)干预组.分别采用酶联免疫吸附法(ELISA)和蛋白质印迹检测支气管肺泡灌洗液(BALF)IL-5含量和肺组织磷酸化p38 MAPK表达的变化,并观察气道阻力、BALF中EOS计数以及肺组织病理学变化.结果:哮喘对照组大鼠肺组织磷酸化p38 MAPK表达水平及气道阻力、BALF中IL-5含量和EOS计数均较正常对照组显著增加(P＜0.01);DEX干预组上述指标较哮喘对照组显著降低(P＜0.01),肺组织病理学损伤程度明显减轻.肺组织磷酸化p38 MAPK表达水平与气道阻力、BALF中IL-5含量和EOS计数之间分别呈显著正相关(r=0.77、0.63、0.65,P＜0.01).结论:p38 MAPK可能参与了支气管哮喘的发病过程.DEX对哮喘的治疗作用至少部分与抑制磷酸化p38 MAPK的表达有关.     

克拉霉素对哮喘大鼠肺组织血红素氧合酶-1的调控

目的:研究哮喘大鼠肺组织中血红素氧合酶-1(HO-1)的表达情况及克拉霉素对HO-1的调控作用;观察其HO-1表达与BALF中EOS占细胞总数的百分比(EOS%)、嗜酸性粒细胞(EOS)、全血COHb的百分比含量之间的相关性。方法:清洁级雄性SD大鼠30只,随机分为正常对照组(N组)、哮喘组(A组)、克拉霉素治疗组(C组),每组10只。测定全血COHb的百分比含量;计数BALF沉渣中细胞总数和分类;计数肺组织中浸润的炎性细胞数;免疫组织化学染色法观察HO-1在哮喘大鼠肺组织的表达。结果:HO-1主要表达在气道上皮细胞,三组HO-1阳性表达的平均吸光度分别为0.07±0.01、0.22±0.03、0.14±0.02。A组HO-1表达水平显著高于N组(P<0.001),C组HO-1蛋白的表达显著低于A组(P<0.01)。HO-1表达水平与全血COHb的百分比含量、BALF中EOS占细胞总数的百分比及肺组织中EOS总数均呈显著正相关(分别为r=0.887,P<0.01;r=0.889,P<0.01;r=0.883,P<0.01)。结论:哮喘大鼠的肺组织HO-1表达水平显著增加,提示HO-1可能参与哮喘发病过程。克拉霉素明显改善哮喘的气道炎症浸润,其作用机制部分是通过抑制HO-1起作用。     

布地奈德对哮喘大鼠支气管Eos和STAT6表达的调控作用

目的:研究布地奈德(BUD)对支气管哮喘大鼠支气管Eos和STAT6表达的调控作用.方法:30只清洁级幼年健康雄性Wisar大鼠经造模后,随机分为对照组、哮喘组和BUD组.实验结束后对支气管肺泡灌洗液(BALF)和肺组织匀浆进行细胞总数、嗜酸性粒细胞(EOS)计数和分类计数;应用ELISA法测定血清中IL-4的含量;采用免疫组化法检测STAT6蛋白表达的变化.结果:(1)哮喘组BALF中细胞总数、EOS绝对值和EOS占细胞总数的百分比(EOS％)均显著高于对照组(P＜0.01),BUD组BALF中上述各项指标较哮喘组均显著降低(P＜0.01);(2)哮喘组BALF中IL-4的浓度显著高于对照组(P＜0.01),BUD组较哮喘组显著降低(P＜0.01);(3)哮喘组支气管上皮细胞STAT6蛋白阳性表达较对照组明显增强(P＜0.01).结论:哮喘大鼠支气管STAT6较强表达,BUD有抑制气道炎症的作用,使IL-4合成减少,从而下调STAT6及其基因表达.     

罗红霉素对哮喘大鼠髓样相关蛋白-8表达的影响

目的探讨罗红霉素对哮喘大鼠髓样相关蛋白-8(MRP8)表达水平及哮喘气道炎症的影响。方法将18只雄性SPF级Brown Norway(BN)大鼠,按照随机数字表法分为正常对照组(C组)6只、哮喘组(A组)6只及罗红霉素治疗组(R组)6只。分别通过卵清白蛋白(OVA)+弗式完全佐剂(FCA)联合致敏,OVA雾化激发构建大鼠哮喘模型,R组用罗红霉素干预。观察各组大鼠肺组织病理结构变化,分析支气管肺泡灌洗液(BALF)中细胞分类计数,酶联免疫吸附试验(ELISA)法检测各组大鼠BALF MRP8水平;蛋白质印迹法测定肺组织MRP8的表达,Pearson相关性分析MRP8与各细胞分类计数的关系。结果 R组BALF细胞总数、嗜酸性粒细胞百分比(EOS%)及中性粒细胞百分比(NEU%)明显高于C组,但低于A组(P均<0.05);R组BALF中白细胞介素(IL)-17、MRP8及肺组织MRP8均高于C组,但低于A组(P均<0.05);Pearson相关性分析显示BALF及肺组织的MRP8水平与BALF细胞总数、EOS%、NEU%、IL-17比例均呈正相关(P均<0.01)。结论急性哮喘大鼠BALF及肺组织MRP8水平升高,并与气道炎症呈正相关,罗红霉素可以通过降低哮喘大鼠MRP8的表达改善哮喘症状。     

左西替利嗪治疗支气管哮喘的疗效及可能机制

目的:研究左西替利嗪治疗哮喘的疗效及可能的机制。方法:以卵蛋白致敏法制备大鼠哮喘模型,40只SD大鼠随机分为5组,即正常对照组、哮喘组、地塞米松组、左西替利嗪高剂量组、左西替利嗪低剂量组,各组连续治疗与激发7d后取材。采用ELISA法测定大鼠血清中白细胞介素4(IL-4)、白细胞介素5(IL-5)、肿瘤坏死因子α(TNF-α)的含量;进行支气管肺泡灌洗液(BALF)细胞计数、肺组织嗜酸粒细胞(Eos)计数及病理学观察等。结果:哮喘组IL-4、IL-5、TNF-α较正常对照组均有显著增加(P<0.01);地塞米松组IL-5、TNF-α水平较哮喘组显著降低(P<0.01);左西替利嗪高、低剂量组IL-4、IL-5、TNF-α均较哮喘组减少(P<0.05或P<0.01)。哮喘组BALF中白细胞总数和肺组织Eos计数较正常对照组明显增加(P<0.01);地塞米松组较哮喘组显著减少(P<0.01);左西替利嗪高、低剂量组BALF中白细胞总数与哮喘组相比明显减少(P<0.01),而其肺组织Eos计数与哮喘组相比无显著差异,明显高于地塞米松组(P<0.01)。病理组织学检查可见哮喘组支气管及血管周围有大量Eos浸润等改变,地塞米松组及左西替利嗪高、低剂量组肺组织病理改变均不同程度的轻于哮喘组。结论:左西替利嗪能显著降低哮喘相关细胞因子的水平,因此其可能成为一种新的治疗哮喘的药物。     

PTEN在哮喘大鼠肺部的表达及罗红霉素的干预效果

目的研究哮喘大鼠与张力蛋白同源的10号染色体缺失的磷酸酶基因(PTEN)的表达和罗红霉素(RXM)对其表达的影响。方法24只体质量(200±10)g的SPF级雄性SD大鼠,随机分为3组:健康对照组(C组)、哮喘组(A组)、罗红霉素组(R组)。对支气管肺泡灌洗液(BALF)进行细胞分类计数;应用双抗体夹心酶联免疫吸附法测定BALF中白细胞介素(IL)-4浓度;采用免疫组织化学法和Westernblot法分别检测PTEN的表达及各组大鼠肺组织PTEN量的变化。结果①健康对照组、罗红霉素组支气管PTEN蛋白的表达分别为[(2.50±0.56),(1.69±0.24)]均高于哮喘组[(1.12±0.26)](P<0.05),其主要表达细胞是支气管上皮细胞;②哮喘组大鼠BALF中IL-4表达明显升高,明显高于健康对照组,罗红霉素干预组BALFIL-4量明显下降,与哮喘组比差异有统计学意义。③哮喘组大鼠支气管PTEN蛋白与BALF中的IL-4浓度呈负相关(r=-0.735,P<0.01),与BALF中的嗜酸粒细胞(EOS)%呈显著负相关,(r=-0.761,P<0.01)。结论气道上皮细胞是PTEN主要表达细胞,哮喘大鼠PTEN蛋白表达明显减少,PTEN能减少Th2因子的表达;罗红霉素可以促进PTEN的表达,可能为其抑制哮喘气道炎症形成的重要作用机制。     

地塞米松对哮喘模型大鼠肺组织病理变化和TGF-β1表达的影响

目的:探讨哮喘时肺组织炎症、中性粒细胞(PMN)、肺泡Ⅱ型(AT-Ⅱ)细胞等的病理改变和转化生长因子-β1(TGF-β1)的表达及地塞米松对其的影响.方法:建立哮喘大鼠模型,支气管肺泡灌洗液(BALF)行细胞计数,光镜、电镜观察肺组织病理改变,免疫组化法检测肺组织TGF-β1的表达.结果:BALF中A组细胞总数、EOS计数显著性高于C组(P<0.01),D组显著性高于C组但低于A组(均P<0.01).肺组织中A组PMN计数显著性高于C组(P<0.01),D组显著性高于A组(P<0.01).A组AT-Ⅱ细胞变性、坏死、崩解、板层体空泡化现象.TGF-β1的表达水平在A组显著性高于C组(P<0.01),D组显著性高于C组但低于A组(分另为P<0.01,0.05).结论:哮喘大鼠肺组织炎症细胞浸润、气道黏膜损伤、AT-Ⅱ细胞损伤、表达水平增加;地塞米松可减少上述病理改变,但对肺组织中PMN数目有增加作用,可能会加重对肺组织的损伤.     

PTEN在哮喘大鼠肺部的表达及地塞米松的干预

目的：研究哮喘大鼠PTEN的表达和地塞米松（DXM）对其表达的影响。方法：24只体重（200±10）g的SPF级雄性SD大鼠,随机分为3组：正常对照组、哮喘组、地塞米松组。对支气管肺泡灌洗液（BALF）进行细胞分类计数;应用双抗体夹心酶联免疫吸附试验法测定BALF中IL-13浓度;采用免疫组化法和Western blot法分别检测PTEN的表达及各组大鼠肺组织PTEN量的变化。结果：正常对照组、地塞米松组支气管PTEN蛋白的表达分别为7.87±0.80、1.80±0.23,均高于哮喘组（0.92±0.23,均为P〈0.01）,其主要表达细胞是支气管上皮细胞;哮喘组大鼠BALF中IL-13表达明显升高,明显高于正常对照组;地塞米松组BALF中IL-13量明显下降,与哮喘组比有统计学意义。哮喘组大鼠支气管PTEN蛋白与BALF中的IL-13浓度呈显著负相关（r=-0.675,P〈0.01）。结论：气道上皮细胞是PTEN主要表达细胞,哮喘大鼠PTEN蛋白表达明显减少,PTEN能减少Th2因子的表达;DXM可以促进PTEN的表达,可能为其抑制哮喘气道炎症形成的重要作用机制。     

灵芝多糖对哮喘大鼠肺泡巨噬细胞GITR/GITRL信号系统表达的影响

目的 通过观察灵芝多糖对哮喘大鼠肺泡巨噬细胞糖皮质激素诱导的肿瘤坏死因子受体(GITR)及其配体(GITRL)表达水平的影响,探讨灵芝多糖治疗哮喘炎症的机制。方法 将40只清洁级SD大鼠随机分为对照组、哮喘组、地塞米松(DXM)干预组和灵芝多糖干预组4组,分离提纯支气管肺泡灌洗液(BALF)中肺泡巨噬细胞,分别采用实时荧光定量逆转录聚合酶链反应(QRT-PCR)及免疫细胞化学方法检测GITR/GITRL mRNA及蛋白在肺泡巨噬细胞上的表达。结果 哮喘组BALF中肺泡巨噬细胞GITR/GITRL mRNA和蛋白的表达水平显著高于对照组(P<0.05或P<0.01);灵芝多糖干预组和DXM干预组GITR/GITRL mRNA和蛋白的表达水平显著低于哮喘组(P<0.05或P<0.01);灵芝多糖干预组GITR/GITRL蛋白的表达水平显著高于DXM干预组(P<0.05),而2组间GITR/GITRL mRNA的表达水平差异无统计学意义。灵芝多糖干预组BALF中细胞总数计数显著低于哮喘组(P<0.01),肺组织炎性病理改变较哮喘组显著减轻。GITR/GITRL mRNA及蛋白均显著呈直线正相关(P<0.01)。结论 灵芝多糖能下调肺泡巨噬细胞GITR/GITRL信号系统的表达、降低BALF中细胞总数计数、减轻肺组织炎性病理改变,起到治疗哮喘的作用,但此作用弱于DXM。     

卡介菌多糖核酸对哮喘小鼠胸腺活化调节趋化因子及mRNA表达的影响

目的观察卡介菌多糖核酸(BCG-PSN)对小鼠哮喘胸腺活化调节趋化因子(thymus and activation regulated chemo-kine,TARC)及mRNA表达的影响。方法以卵清白蛋白(OVA)致敏和激发建立小鼠哮喘模型。30只清洁级♂Balb/c小鼠随机分为3组,每组10只:正常对照组、哮喘组、BCG-PSN治疗组。末次激发24h后留取支气管肺泡灌洗液(BALF)及肺组织。BALF行细胞计数及分类;应用酶联免疫吸附试验(ELISA)法测定BALF中TARC、IL-4和IFN-γ蛋白的浓度;光镜观察肺组织病理变化;逆转录-聚合酶链反应(RT-PCR)法测定肺组织中TARC mRNA的表达;采用免疫组织化学法测定肺组织中TARC蛋白的表达。结果与正常对照组相比,哮喘组BALF中细胞总数、嗜酸粒细胞(EOS)绝对值及百分比、TARC和IL-4浓度、肺组织中TARC蛋白及mRNA的表达均增高,BALF中IFN-γ浓度低于正常对照组。经BCG-PSN干预后,BALF中细胞总数、EOS绝对数及百分比,TARC、IL-4浓度较哮喘组均下降,肺组织中TARC蛋白及mRNA的表达较哮喘组均下调,BALF中IFN-γ浓度较哮喘组增高。免疫组化显示TARC蛋白主要表达于支气管上皮细胞。BALF中TARC浓度与EOS绝对值、IL-4浓度呈正相关。结论卡介菌多糖核酸可降低TARC在肺组织中的表达,降低气道炎症。     

Methodological aspects on measurement of Clara cell protein in urine as a biomarker for airway toxicity, compared with serum levels

The Clara cell protein CC16, secreted from Clara cells in the lung, is discussed as a potential biomarker for toxic effects on the airways. An increased concentration of CC16 in serum may be caused by increased permeability of the lungs, caused by high levels of air pollution. Since CC16 is eliminated by renal excretion, it may be possible to use urine instead of serum samples. Few studies have been conducted on urinary CC16 (U-CC16), however.The aim was to investigate the optimal way of sampling and quantifying CC16 in urine samples and compare CC16 in human serum and urinary samples. Repeated sampling was performed in two groups of healthy subjects. First morning urine, 24 h urine, and matched blood and urine samples were collected.The excretion of U-CC16 increased over the day, e.g. from 0.08 microg h(-1) in the morning to 0.28 microg h(-1) in daytime and 0.16 microg h(-1) in the evening (medians in males). Morning samples (microg h(-1)) from males properly reflected the 24 h excretion (r = 0.91). The best correlation with 24 h excretion was obtained with creatinine-corrected first morning urine samples (r > 0.9). Generally, females had lower excretion of CC16 than males (medians 2.5 microg 24 h(-1) in females and 16 microg 24 h(-1) in males). There was significant intraindividual variation, but the interindividual variation was larger in both groups. There was an association between serum CC16 (S-CC16) and U-CC16 in morning samples. With optimal methods for sampling U-CC16, urine samples may be used in experimental studies of air pollution.     

Foam cell formation of alveolar macrophages in Clara cell ablated mice inhaling crystalline silica

We investigated the function of Clara cells in vivo during exposure to inhaled crystalline silica by morphological and immunohistochemical examination of intra-alveolar cells and alveolar macrophages in Clara cell-ablated mice. The Clara cells of male FVB/n mice (8–12 weeks old) were ablated by intraperitoneal administration of naphthalene (300?mg/kg). The mice were then exposed to crystalline silica (Min-U-Sil-5, 97.1?±?9.5?mg/m³, 6 hours/day, 5 days/week) for up to two weeks. The lungs were assessed by morphometry, as well as by immunohistochemistry of CD36, lectin-like oxygenated low-density lipoprotein receptor (LOX)-1, and matrix metalloproteinases (MMPs) -2, -9 and -12. There was a significantly greater number of intra-alveolar cells in Clara cell-ablated mouse groups than in wild-type mouse groups that were exposed to crystalline silica. A marked number of foamy alveolar macrophages were only detected in the Clara cell-ablated group exposed to crystalline silica, indicating that Clara cells inhibit infiltration and foam cell formation of alveolar macrophages. Immunohistochemical analysis indicated that foamy alveolar macrophages in the Clara cell-ablated group that inhaled crystalline silica overexpress CD36 and LOX-1, indicating upregulation of scavenger receptors of alveolar macrophages. These cells also express MMP-2, -9 and -12, suggesting increased gelatinolytic and elastolytic activities. Our findings suggest that Clara cells not only inhibit infiltration of alveolar macrophages but also their phagocytotic and gelatinolytic functions in silica-induced pulmonary injury.     

Clara cell secretory protein: determination of serum levels by an enzyme immunoassay and its importance as an indicator of bronchial asthma in children

Clara cell secretory protein (CC16) is a 16kDa protein secreted by Clara cells in the lining fluid of bronchiolar and bronchial epithelium. CC16 presents several biologic properties, and has been shown to have immunomodulatory and anti-inflammatory activity. It may play a role in controlling inflammation in the airway. There is some evidence that the CC16 level is primarily lower in adult individuals with bronchial asthma, thus contributing to its pathophysiology. This study was designed to examine CC16 serum levels of children, healthy and with asthma. An enzyme solid phase immunoassay utilizing monoclonal antibody to CC16 was the analytical method to determine the protein concentration in blood sera. The method showed excellent linearity, high sensitivity (detection limit: <50 ng/l) and precision. It was found that asthmatic children appear significantly lower levels (P < 0.001) of CC16 in serum as compared to healthy ones. It is, therefore, concluded that CC16 may be a useful diagnostic index of bronchial asthma in the early child-age.     

Effects of repeated Cr(VI) intratracheal instillation on club (Clara) cells and activation of nuclear factor-kappa B pathway via oxidative stress

Hexavalent chromium [Cr(VI)] exposure is known to induce respiratory inflammation and contribute to lung cancer development, but little is known about its target cell type in lung. In the current study, we investigated the effects of repeated Cr(VI) intratracheal instillation on club (Clara) cells and club (Clara) cell secretory protein (CC16) in rats and explored whether the nuclear factor-kappa B (NF-κB) related pathway was involved. We also studied the role of orally delivered Zn against Cr-induced adverse health effects. For four weeks, sixty Sprague-Dawley male rats received weekly intratracheal instillation of potassium dichromate (K₂Cr₂O₇) at 0, 0.063 and 0.630 mg Cr/kg with or without daily intragastric administration of zinc sulfate (ZnSO₄) at 10 mg Zn/kg. Results showed that exposure to Cr(VI) significantly increased the organ coefficient of lung (organ weight as a percentage of body weight), albumin and total protein level in bronchoalveolar lavage fluid (BALF), indicating lung injury and compromised bronchoalveolar/blood barrier (BA/BB) integrity. With increasing Cr(VI) dose, the secretion of CC16 decreased in a dose-dependent manner, suggesting that CC16 can serve as a peripheral biomarker for club cell damage during early lung injury induced by Cr(VI). Increased expression of NF-κB were observed in club cells in both Cr-exposed groups, indicating upregulation of NF-κB, which can be induced by reactive oxygen species (ROS) generated by club cells during Cr reduction with repetitive Cr(VI) exposure. Cr-induced DNA damage was also observed, as significant increase of 8-OHdG was found with Cr exposure at 0.630 mg/kg week. Oral Zn supplementation did not alleviate changes in serum CC16 level under Cr(VI) exposure, indicating its failure in protecting against Cr(VI)-induced club cell damage.     

Pulmonary heat shock protein expression after exposure to a metabolically activated Clara cell toxicant: relationship to protein adduct formation

Heat shock proteins/stress proteins (Hsps) participate in regulation of protein synthesis and degradation and serve as general cytoprotectants, yet their role in lethal Clara cell injury is not clear. To define the pattern of Hsp expression in acute lethal Clara cell injury, mice were treated with the Clara cell-specific toxicant naphthalene (NA), and patterns of expression compared to electrophilic protein adduction and previously established organellar degradation and glutathione (GSH) depletion. In sites of lethal injury (distal bronchiole), prior to organellar degradation (1 h post-NA), protein adduction is detectable and ubiquitin, Hsp 25, Hsp 72, and heme-oxygenase 1 (HO-1) are increased. Maximal Hsp expression, protein adduction, and GSH depletion occur simultaneous (by 2-3 h) with early organelle disruption. Hsp expression is higher later (6-24 h), only in exfoliating cells. In airway sites (proximal bronchiole) with nonlethal Clara cell injury elevation of Hsp 25, 72, and HO-1 expression follows significant GSH depletion (greater than 50% 2 h post-NA). This data build upon our previous studies and we conclude that (1) in lethal (terminal bronchiole) and nonlethal (proximal bronchiole) Clara cell injury, Hsp induction is associated with the loss of GSH and increased protein adduction, and (2) in these same sites, organelle disruption is not a prerequisite for Hsp induction.     

Immunohistochemical analysis of Clara cell secretory protein expression in a transgenic model of mouse lung carcinogenesis

Immunohistochemical methods have been widely used to determine the histogenesis of spontaneous and chemically-induced mouse lung tumors. Typically, antigens for either alveolar Type II cells or bronchiolar epithelial Clara cells are studied. In the present work, the morphological and immunohistochemical phenotype of a transgenic mouse designed to develop lung tumors arising from Clara cells was evaluated. In this model, Clara cell-specific transformation is accomplished by directed expression of the SV40 large T antigen (TAg) under the mouse Clara cell secretory protein (CC10) promoter. In heterozygous mice, early lesions at 1 month of age consisted of hyperplastic bronchiolar epithelial cells. These progressed to adenoma by 2 months as proliferating epithelium extended into adjacent alveolar spaces. By 4 months, a large portion of the lung parenchyma was composed of tumor masses. Expression of constitutive CC10 was diminished in transgenic animals at all time points. Only the occasional cell or segment of the bronchiolar epithelium stained positively for CC10 by immunohistochemistry, and all tumors were found to be uniformly negative for staining. These results were corroborated by Western blotting, where CC10 was readily detectable in whole lung homogenate from nontransgenic animals, but not detected in lung from transgenic animals at any time point. Tumors were also examined for expression of surfactant apoprotein C (SPC), an alveolar Type II cell-specific marker, and found to be uniformly negative for staining. These results indicate that, in this transgenic model, expression of CC10, which is widely used to determine whether lung tumors arise from Clara cells, was reduced and subsequently lost during Clara cell tumor progression.     

Association between occupational exposure to arsenic and neurological, respiratory and renal effects

Occupational exposure by inhalation in copper smelter is associated with several subclinical health phenomena. The respiratory tract is usually involved in the process of detoxication of inhaled noxious agents which, as arsenic, can act as inductors of oxidative stress (Lantz, R.C., Hays, A.M., 2006. Role of oxidative stress in arsenic-induced toxicity. Drug Metab. Rev. 38, 791-804). It is also known that irritating fumes affect distal bronchioles of non-ciliated, epithelial Clara cells, which secrete anti-inflammatory and immunosuppressive Clara cell protein (CC16) into the respiratory tract.The study group comprised 39 smelters employed at different workplaces in a copper foundry, matched for age and smoking habits with the control group (n = 16). Subjective neurological symptoms (SNS), visual evoked potentials (VEP), electroneurographic (EneG) and electroencephalographic (EEG) results were examined in the workers and the relationships between As concentration in the air (As-Air) and urine (As-U) were assessed. Effects of exposure were expressed in terms of biomarkers: CC16 as early pulmonary biomarker and β₂-microglobulin (β₂M) in urine and serum and retinol binding protein (RBP) as renal markers, measured by sensitive latex immunoassay.The concentrations of arsenic exceeded about two times the Threshold Limit Values (TLV) (0.01 mg/m³). The contents of lead did not exceed the TLV (0.05 mg/m³).Low CC16 levels in serum (12.1 μg/l) of workers with SNS and VEP symptoms and highest level As-U (x_a 39.0 μg/l) were noted earliest in relation to occupational time. Moreover, those effects were associated with increased levels of urinary and serum β₂M and urinary RBP.Results of our study suggested the initiative key role of oxidative stress in triggering the processes that eventually lead to the subclinical effects of arsenic on the nervous system.     

γ-Glutamyl transpeptidase null mice fail to develop tolerance to coumarin-induced Clara cell toxicity

Coumarin was used as a model Clara cell toxicant to test the hypothesis that tolerance to injury requires increased γ-glutamyl transpeptidase (GGT) activity. Wildtype (GGT^+/+) and GGT-deficient (GGT^−/−) mice on a C57BL/6/129SvEv hybrid background were dosed orally with corn oil (vehicle) or coumarin (200 mg/kg). In vehicle-treated mice, Clara cell secretory protein (CC10) expression was distributed throughout the bronchiolar epithelium. After one dose of coumarin, CC10 expression was dramatically reduced and the bronchiolar epithelium was devoid of Clara cells in GGT^+/+ and GGT^−/− mice. In wildtype mice, 9 doses of coumarin produced tolerance, characterized as a renewed bronchiolar epithelium with Clara cells expressing CC10 along with a 40% increase in total glutathione (GSH) and a 7-fold increase in GGT activity in the lung. In contrast, tolerance was not observed in GGT^−/− mice. To assess whether changes in whole lung levels of GSH and GGT activity reflect Clara cell specific changes an enriched population of cells was isolated from female wildtype B6C3F1 mice made tolerant to coumarin. Compared to Clara cells from control mice, GSH and GGT activity increased 3- and 13-fold, respectively. Collectively, these data suggest Clara cell tolerance to coumarin toxicity requires increased GGT activity favoring enhanced GSH synthesis.     

Increased serum and urinary concentrations of lung clara cell protein in rats acutely exposed to ozone.

Clara cell protein (CC16) is a 16-17-kDa protein secreted by Clara cells in the bronchial lining fluid of the lung from which it passively diffuses into serum before being eliminated by the kidneys. The concentration of CC16 in serum has recently been proposed as a peripheral marker of the integrity of Clara cells and/or of the bronchoalveolar/blood barrier. To evaluate the sensitivity of this new lung marker to acute epithelial damage induced by ozone (O(3)), CC16 was determined in the serum of rats after a single 3-h exposure to 0.3, 0.6, or 1 ppm O(3). The urinary excretion of the protein was also studied in rats repeatedly exposed to 1 ppm O(3), 3 h/day, for up to 10 days. The concentrations of CC16 in the lung or trachea homogenates, the lung CC16 mRNA levels, and classical markers of lung injury in bronchoalveolar lavage fluid (BALF) were also determined. O(3) produced a transient increase of CC16 concentration in serum that reached values on average 13 times above normal 2 h after exposure to 1 ppm O(3). The intravascular leakage of CC16 was dose-dependent and correlated with the extent of lung injury as assessed by the levels of total protein, LDH, and inflammatory cells in BALF. This effect was most likely responsible for the concomitant marked reduction of CC16 concentrations in BALF and lung homogenate, since the CC16 mRNA levels in the lungs were unchanged and the absolute amounts of CC16 leaking into serum or lost from the respiratory tract were similar. These changes were paralleled by an elevation of the urinary excretion of CC16 resulting from an overloading of the tubular reabsorption process. These results demonstrate that the assay of CC16 in serum and even in urine represents a new noninvasive test to detect the increased lung epithelial permeability induced by O(3).