Polydatin alleviates bleomycin-induced pulmonary fibrosis and alters the gut microbiota in a mouse model

To investigate the effect and mechanism of polydatin on bleomycin (BLM)-induced pulmonary fibrosis in a mouse model. The lung fibrosis model was induced by BLM. The contents of TNF-α, LPS, IL-6 and IL-1β in lung tissue, intestine and serum were detected by ELISA. Gut microbiota diversity was detected by 16S rDNA sequencing; R language was used to analyse species composition, α-diversity, β-diversity, species differences and marker species. Mice were fed drinking water mixed with four antibiotics (ampicillin, neomycin, metronidazole, vancomycin; antibiotics, ABx) to build a mouse model of ABx-induced bacterial depletion; and faecal microbiota from different groups were transplanted into BLM-treated or untreated ABx mice. The histopathological changes and collagen I and α-SMA expression were determined. Polydatin effectively reduced the degree of fibrosis in a BLM-induced pulmonary fibrosis mouse model; BLM and/or polydatin affected the abundance of the dominant gut microbiota in mice. Moreover, faecal microbiota transplantation (FMT) from polydatin-treated BLM mice effectively alleviated lung fibrosis in BLM-treated ABx mice compared with FMT from BLM mice. Polydatin can reduce fibrosis and inflammation in a BLM-induced mouse pulmonary fibrosis model. The alteration of gut microbiota by polydatin may be involved in the therapeutic effect.     

白介素11拮抗剂对实验性小鼠肺纤维化的作用

目的:观察拮抗白介素11(IL-11)对博来霉素(BLM)诱导的实验性小鼠肺纤维化的作用.方法:将120只雄性C57BL/6小鼠随机分为正常对照组、IL-11拮抗剂组、BLM组和BLM+IL-11拮抗剂组(每组各30只).BLM组和BLM+IL-11拮抗剂组小鼠一次性气管注射BLM(1.5 mg/kg)诱导肺纤维化.于...     

Increased expression of collagen-binding heat shock protein 47 in murine bleomycin-induced pneumopathy

The 47-kDa heat shock protein 47 (HSP47) is a collagen-specific molecular chaperone that has been shown to play a major role during the processing and/or secretion of procollagen. Expression of HSP47 has been reported to increase in parallel with expression of collagens during the progression of various fibrosis models. The aim of the present study was to investigate the association between HSP47 expression and collagen accumulation in bleomycin (BLM)-induced murine fibrosis. We investigated the expression of HSP47 protein and mRNA using immunohistochemical analysis and semi-quantitative RT-PCR in murine BLM-induced pulmonary fibrosis. Immunohistochemical analysis showed that higher expression of HSP47 protein was present in BLM-induced pulmonary fibrosis compared with controls. HSP47 was localized predominantly in alpha-smooth muscle actin-positive myofibroblasts, F4/80 negative, surfactant protein-A-positive type II pneumocytes, and F4/80-positive macrophages. RT-PCR also demonstrated an increase of HSP47 mRNA expression in BLM-treated lungs. Moreover, the relative amounts of HSP47 mRNA correlated significantly with the lung hydroxyproline content as an indicator of pulmonary fibrosis in BLM-treated lungs (r = 0.406, P <0.05). Our results suggest that these cells may play a role in the fibrotic process of BLM-treated lungs through upregulation of HSP47.     

Secretoglobin 3A2 Exhibits Anti-Fibrotic Activity in Bleomycin-Induced Pulmonary Fibrosis Model Mice

Objective

Secretoglobin (SCGB) 3A2 is a novel lung-enriched cytokine, previously shown to exhibit anti-inflammatory, growth factor, and anti-fibrotic activities. The latter activity was demonstrated using exogenously-administered recombinant SCGB3A2 in the bleomycin (BLM)-induced pulmonary fibrosis model. Whether SCGB3A2 exhibits anti-fibrotic activity in vivo is not known.

Methods

Mice null for the Scgb3a2 gene were subjected to the BLM-induced pulmonary fibrosis model, and the severity of pulmonary fibrosis determined using histological and biochemical methods.

Results

BLM treatment caused weight loss of both Scgb3a2-null and wild-type mice, however, the loss was far more pronounced in BLM-treated Scgb3a2-null than wild-type mice, and the weight of day 21 of BLM-treated Scgb3a2-null mice was about half of that of BLM-treated wild-type mice. Hematoxylin & Eosin, Masson Trichrome, and Sirius Red staining of lung sections, Ashcroft fibrosis scores, hydroxyproline contents, and the levels of mRNAs encoding various collagens demonstrated that BLM-treated Scgb3a2-null mouse lungs had more severe fibrosis than those of wild-type mouse lungs. Total and differential inflammatory cell numbers in bronchoalveolar lavage fluids, and levels of lung mRNAs including those encoding Th2 cytokines such as IL-4 and profibrotic cytokines such as TGFβ were higher in BLM-treated Scgb3a2-null mouse lungs as compared to those of wild-type mouse lungs. In contrast, mRNAs encoding surfactant proteins A, B, C, and D, and SCGB1A1 did not differ between BLM-treated Scgb3a2-null and wild-type mouse lungs.

Conclusion

The role of SCGB3A2 in fibrosis was revisited using Scgb3a2-null mice and littermate controls in the BLM-induced pulmonary fibrosis model. The pulmonary fibrosis in the Scgb3a2-null mice was more severe than the wild-type controls, thus establishing that SCGB3A2 has anti-fibrotic activity in vivo. Importantly, surfactant proteins and SCGB1A1 appear not to be involved in the susceptibility of Scgb3a2-null mice to BLM-induced pulmonary fibrosis.     

肺纤维化初期肺动脉高压大鼠肺动脉反应性的变化

目的：观察肺纤维化初期肺动脉高压大鼠肺动脉血管反应性的变化。方法：66只雄性SD大鼠,随机分为博莱霉素（BLM）组和手术对照（Sham）组。BLM组为气管内一次性滴注BLM（5 mg/kg）;Sham组为气管内滴注等容量的生理盐水（NS）。应用离体血管张力检测技术测定大鼠肺动脉血管反应性变化;用HE显示肺动脉壁病理形态学变化;Masson染色检测肺纤维化程度;右心漂浮导管技术测定大鼠平均肺动脉压。结果：①BLM组大鼠的肺动脉血管（保留内皮和去内皮）对苯肾上腺素（PE）的收缩反应均弱于Sham组（P均〈0.05）。②BLM组大鼠肺动脉血管（保留内皮）对氯化乙酰胆碱（Ach）的舒张反应明显弱于Sham组（P〈0.01）。③Sham组有内皮的肺动脉血管对L-NAME和PE联合作用的收缩反应明显强于PE单独作用（P〈0.01）,而BLM组有内皮肺动脉血管对L-NAME和PE联合作用的收缩反应与对PE单独作用比,其差异无统计学意义（P〉0.05）。④BLM组肺动脉内皮细胞脱落。⑤BLM组大鼠肺组织呈现纤维增生初期的病理特征,且大鼠的平均肺动脉压明显高于Sham组（P〈0.05）。结论：肺纤维化形成初期肺动脉高压大鼠肺动脉血管反应性出现异常。     

Melatonin Inhibits Endoplasmic Reticulum Stress and Epithelial-Mesenchymal Transition during Bleomycin-Induced Pulmonary Fibrosis in Mice

Several reports indicate that melatonin alleviates bleomycin (BLM)-induced pulmonary fibrosis in rodent animals. Nevertheless, the exact mechanism remains obscure. The present study investigated the effects of melatonin on endoplasmic reticulum (ER) stress and epithelial-mesenchymal transition (EMT) during BLM-induced lung fibrosis. For the induction of pulmonary fibrosis, mice were intratracheally injected with a single dose of BLM (5.0 mg/kg). Some mice were intraperitoneally injected with melatonin (5 mg/kg) daily for a period of 3 wk. Twenty-one days after BLM injection, lung fibrosis was evaluated. As expected, melatonin significantly alleviated BLM-induced pulmonary fibrosis, as evidenced by Sirius red staining. Moreover, melatonin significantly attenuated BLM-induced EMT to myofibroblasts, as determined by its repression of α-SMA expression. Further analysis showed that melatonin markedly attenuated BLM-induced GRP78 up-regulation and elevation of the cleaved ATF6 in the lungs. Moreover, melatonin obviously attenuated BLM-induced activation of pulmonary eIF2α, a downstream target of the PERK pathway. Finally, melatonin repressed BLM-induced pulmonary IRE1α phosphorylation. Correspondingly, melatonin inhibited BLM-induced activation of XBP-1 and JNK, two downstream targets of the IRE1 pathway. Taken together, these results suggest that melatonin alleviates ER stress and ER stress-mediated EMT in the process of BLM-induced pulmonary fibrosis.     

C-type natriuretic peptide attenuates bleomycin-induced pulmonary fibrosis in mice

C-type natriuretic peptide (CNP) has been shown to play an important role in the regulation of vascular tone and remodeling. However, the physiological role of CNP in the lung remains unknown. Accordingly, we investigated whether CNP infusion attenuates bleomycin (BLM)-induced pulmonary fibrosis in mice. After intratracheal injection of BLM or saline, mice were randomized to receive continuous infusion of CNP or vehicle for 14 days. CNP infusion significantly reduced the total number of cells and the numbers of macrophages, neutrophils, and lymphocytes in bronchoalveolar lavage fluid. Interestingly, CNP markedly reduced bronchoalveolar lavage fluid IL-1beta levels. Immunohistochemical analysis demonstrated that CNP significantly inhibited infiltration of macrophages into the alveolar and interstitial regions. CNP infusion significantly attenuated BLM-induced pulmonary fibrosis, as indicated by significant decreases in Ashcroft score and lung hydroxyproline content. CNP markedly decreased the number of Ki-67-positive cells in fibrotic lesions of the lung, suggesting antiproliferative effects of CNP on pulmonary fibrosis. Kaplan-Meier survival curves demonstrated that BLM mice treated with CNP had a significantly higher survival rate than those given vehicle. These results suggest that continuous infusion of CNP attenuates BLM-induced pulmonary fibrosis and improves survival in BLM mice, at least in part by inhibition of pulmonary inflammation and cell proliferation.     

Nitric oxide exerts protective effects against bleomycin-induced pulmonary fibrosis in mice

Background

Increased expression of nitric oxide synthase (NOS) and an increase in plasma nitrite plus nitrate (NOx) have been reported in patients with pulmonary fibrosis, suggesting that nitric oxide (NO) plays an important role in its development. However, the roles of the entire NO and NOS system in the pathogenesis of pulmonary fibrosis still remain to be fully elucidated. The aim of the present study is to clarify the roles of NO and the NOS system in pulmonary fibrosis by using the mice lacking all three NOS isoforms.

Methods

Wild-type, single NOS knockout and triple NOS knockout (n/i/eNOS^−/−) mice were administered bleomycin (BLM) intraperitoneally at a dose of 8.0 mg/kg/day for 10 consecutive days. Two weeks after the end of the procedure, the fibrotic and inflammatory changes of the lung were evaluated. In addition, we evaluated the effects of long-term treatment with isosorbide dinitrate, a NO donor, on the n/i/eNOS^−/− mice with BLM-induced pulmonary fibrosis.

Results

The histopathological findings, collagen content and the total cell number in bronchoalveolar lavage fluid were the most severe/highest in the n/i/eNOS^−/− mice. Long-term treatment with the supplemental NO donor in n/i/eNOS^−/− mice significantly prevented the progression of the histopathological findings and the increase of the collagen content in the lungs.

Conclusions

These results provide the first direct evidence that a lack of all three NOS isoforms led to a deterioration of pulmonary fibrosis in a BLM-treated murine model. We speculate that the entire endogenous NO and NOS system plays an important protective role in the pathogenesis of pulmonary fibrosis.     

Baicalin prevents the up-regulation of connective tissue growth factor in fibrotic lungs of rats

To clarify the mechanism underlying the preventive effect of baicalin (Bai) on fibrosis in lung, we investigated the influence of Bai on the up-regulation of connective tissue growth factor (CTGF) in fibrotic lungs. Male Sprague-Dawley (SD) rats were divided into four groups randomly: normal saline (NS)+NS group (a single intratracheal instillation of NS plus i.p. injection of NS), NS+Bai group (intratracheal instillation of NS plus i.p. injection of Bai), bleomycin (BLM)+NS group (intratracheal instillation of BLM plus i.p. injection of NS) and BLM+Bai group (intratracheal instillation of BLM plus i.p. injection of Bai). All the i.p. injections were performed once daily. On day 28 after intratracheal instillation of BLM or NS, the rats were sacrificed for lung tissue sampling. As the index of the severity of pulmonary fibrosis, the content of hydroxyproline in lungs was analyzed by chloramine T method. The expression levels of CTGF mRNA and protein in the lungs were detected by RT-PCR and immunohistochemistry, respectively. The results showed that, compared to the rats in NS+NS group, the rats in BLM+NS group showed increased hydroxyproline content and higher levels of CTGF mRNA and protein expressions (P<0.01), suggesting that BLM had induced fibrosis in lung and up-regulated CTGF expression in the fibrotic lungs. Administration of different dosages of Bai (6, 12.5 and 50 mg/kg per d, for 28 days) into the BLM-treated rats reduced the increased content of hydroxyproline, and ameliorated the up-regulation of CTGF mRNA and protein levels, respectively. These results suggest that Bai could prevent the up-regulation of CTGF expression in fibrotic lungs of rats receiving BLM instillation, which might be one of the mechanisms underlying the preventive effect of Bai on pulmonary fibrosis.     

大鼠肺纤维化形成中肺内肥大细胞结缔组织生长因子的表达

目的：观察博莱霉素（BLM）诱导肺纤维化形成中肺肥大细胞（MCs）是否表达结缔组织生长因子（CTGF）。方法：32只雄性SD大鼠,随机分为博莱霉素（BLM）组和对照（Control）组（n=16）。BLM组为气管内一次性滴注BLM（5mg／ks）;Control组为气管内滴注与BLM等容量的生理盐水（NS）。各组分别在气管滴注后第14天和第28天处死大鼠,取肺组织样本。用氯胺-T法检测肺组织羟脯氨酸含量以判断肺纤维化程度;用甲苯胺蓝染色显示肺组织切片中的MCs;免疫组化染色显示肺CTGF的表达和分布。结果：①与对照大鼠比,气管内滴注BLM后第28天大鼠的肺羟脯氨酸含量明显增高（P〈0．01）。②与对照大鼠比,气管内滴注BLM后第14天和第28天大鼠肺内MCs数明显增多（均P〈0．01）,肺内CTGF表达上调（均P〈0．01）。③对照大鼠肺内未见CTGF免疫阳性的MCs;而气管内滴注BLM后第14天和第28天大鼠肺内病灶区中有CTGF免疫阳性的MCs。结论：肺纤维化形成中肺MCs表达CTGF,这可能是MCs促进肺纤维化的作用机制之一。     

EGFR 对博莱霉素诱导小鼠肺纤维化中上皮- 间质转分化的影响

目的:探讨表皮生长因子受体(EGFR)在肺内的表达对博莱霉素(BLM)诱导小鼠肺纤维化中上皮-间质转分化的影响。方法:将40只4～6周龄C57BLB/c雄性小鼠随机分为正常对照组(气管滴入PBS),纤维化组(气管滴入BLM 3 mg/kg),EGFRRNAi组(气管滴入BLM 3 mg/kg+气管滴入siRNA 20μl)和RNAi阴性对照组(气管滴入BLM 3 mg/kg+气管滴入siRNA阴性对照20μl)。实验第10天处死小鼠,收获肺组织,检测羟脯氨酸含量;采用逆转录-聚合酶链反应(RT-PCR)法检测EGFR和α平滑肌肌动蛋白(α-SMA)mRNA的表达;肺组织切片行HE染色观察肺组织病理改变,免疫组化染色检测EGFR和α-SMA表达。结果:纤维化组EGFR和α-SMA两者的mRNA和蛋白表达均较正常对照组显著增加;RNAi组肺病理损伤较纤维化组减轻,气道上皮下胶原沉积及肺羟脯氨酸含量减少(P<0.05),肺组织EGFR和α-SMA两者的mRNA和蛋白表达均较纤维化组显著下降(P<0.05)。结论:在博来霉素诱导的肺纤维化中EGFR RNAi抑制EGFR活化,下调α-SMA的表达,减轻了博莱霉素诱导的肺纤维化病理改变。其抑制肺纤维化病理过程可能与其抑制上皮-间质转分化(EMT)有关。     

Dietary supplementation with taurine and niacin prevents the increase in lung collagen cross-links in the multidose bleomycin hamster model of pulmonary fibrosis

Taurine and niacin have been previously found to block the accumulation of collagen in lung in the multidose bleomycin hamster model of pulmonary fibrosis. Previous studies have found an increase in the pulmonary collagen cross-links dihydroxylysinonoroleucine (DHLNL) and hydroxypyridinium (OHP) in the single dose bleomycin rat model. In this study, we asked if taurine and niacin would block the increase in DHLNL and OHP in the multidose bleomycin hamster model of lung fibrosis. Hamsters were intratracheally instilled with three consecutive doses of saline or bleomycin sulfate 1 week apart (2.5, 2.0,1.5 units/ 5 mL/kg). Animals were fed diet containing either 2.5% niacin and 2.5% taurine or control diet throughout the experiment. The four groups were saline-instilled with control diet (SCD), bleomycin instilled with control diet (BCD), bleomycin-instilled with taurine-niacin in diet (BTN), and saline-instilled with taurine-niacin in diet (STN). Animals were sacrificed at 1, 4, and 8 weeks after the last bleomycin instillation. Hydroxyproline per lung in the BCD group was significantly elevated by 38, 56, and 60% over the SCD group at 1, 4, and 8 weeks, respectively. There were no statistically significant differences among the four groups in DHLNL (mmole) per mole collagen at the 1 or 8 week time point. At four weeks, DHLNL was significantly elevated by 46.4% in the BCD group over the SCD group. The OHP (mmole) per mole of collagen at 1 and 4 weeks in the BCD group was not statistically different from the SCD group. However, at 8 weeks, this was significantly elevated by 31.4% over the SCD group. The DHLNL and OHP contents per mole of collagen were increased in the multidose bleomycin hamster model. Treatment with taurine and niacin in combination prevented the bleomycin-induced increases in the DHLNL and OHP contents of the lung collagen and this may be one of the mechanisms for their antifibrotic effect in this multidose bleomycin hamster model of pulmonary fibrosis.     

小剂量辣椒素抗小鼠肺纤维化的作用及其机制

目的: 观察小剂量辣椒素(Cap)抗小鼠肺纤维化的作用是否与其激动瞬时电位感受器香草酸受体1(TRPV1)有关。方法: 实验设对照(CON)组、博莱霉素(BLM)组、Cap(0.5、1、2 mg/kg)剂量组及Cap (2 mg/kg)+ TRPV1受体阻断剂SB-452533(2.5 mg/kg)剂量组,每组n=12。BLM(3.5 mg/kg)气管注射诱导肺纤维化小鼠模型。造模后连续皮下注射给药21 d。血浆降钙素基因相关肽(CGRP)浓度采用ELISA法快速测定。肺组织病理变化和胶原沉积分别采用HE染色、Masson染色和免疫组化进行检测。肺组织α-CGRP、β-CGRP、I 型胶原(collagen I)、III 型胶原(collagen III)、E钙粘蛋白(E-Cadherin)、紧密连接蛋白-1(ZO-1)、波形蛋白(Vimentin)、α-平滑肌肌动蛋白(α-SMA)、TRPV1、磷酸化ERK1/2(p-ERK1/2)和真核翻译起始因子3a(eIF3a)mRNA及蛋白表达分别采用qPCR和(或)Western blot法检测。结果: 与BLM组相比,小剂量Cap给药21 d后,病理检查发现小鼠肺纤维化明显减轻;肺组织胶原表达明显下降(P＜0.05或P＜0.01);肺泡上皮细胞上皮间质转分化(EMT)明显受到抑制(E-Cadherin和ZO-1的表达明显升高(P＜0.05或P＜0.01)而Vimentin和α-SMA的表达明显降低(P＜0.05或P＜0.01));TRPV1和CGRP表达水平明显升高(P＜0.05或P＜0.01)而ERK磷酸化水平和eIF3a表达水平明显降低(P＜0.05或P＜0.01)。但当使用TRPV1受体阻断剂阻断TRPV1后,小剂量Cap逆转肺泡EMT、改善肺纤维化的作用被显著取消,同时CGRP表达水平又明显降低(P＜0.01)而p-ERK1/2和eIF3a的表达水平又明显升高(P＜0.01)。结论: 小剂量Cap能够逆转肺泡上皮细胞EMT、缓解肺纤维化。其机制可能与其激动TRPV1、促进CGRP释放,进而抑制ERK磷酸化和下调eIF3a的表达有关。     

不同剂量博莱霉素诱导小鼠肺纤维化的差异及动态变化

目的探讨博来霉素诱导小鼠肺纤维化最佳剂量和方法。方法 126只8周龄雄性ICR小鼠,随机分成一次性大剂量模型和多次小剂量模型。一次性大剂量模型分为200 mg/(kg.bw)BLM组、150 mg/(kg.bw)BLM组、100 mg/(kg.bw)BLM组及阴性对照组(DN组),每组18只,分别经尾静脉一次性注射BLM 200、150、100mg/(kg.bw)及生理盐水10 mL/(kg.bw),各组分别于第7、14、21天各处死6只。多次小剂量模型分为每日10 mg/(kg.bw)BLM组及阴性对照组(N组),分别经尾静脉注射BLM 10 mg/(kg.bw)及生理盐水10 mL/(kg.bw),每天1次,连续注射14 d,两组分别于第14、21、28天各处死6只。留取肺组织,观察肺组织病理改变,检测Ⅲ型胶原的含量,观察小鼠体重及生存率。结果①在一次性大剂量模型中,BLM各剂量组肺泡炎症评分及肺纤维化评分与正常组相比,除100 mg/(kg.bw)BLM组和150 mg/(kg.bw)BLM组在第7天的模型差异无显著性外(P>0.05),其余各组差异均有显著性(P<0.05);各个剂量组Ⅲ型胶原的表达面积与正常组相比,除100 mg/(kg.bw)BLM组在第7天的模型差异无显著性外(P>0.05),其余各组均较正常组高(P<0.05),各个剂量组分别在第21天达到高峰,以200 mg/(kg.bw)BLM组第21天组Ⅲ型胶原的表达面积最高;该模型小鼠各剂量组死亡率为0。②在多次小剂量模型中,各组的肺泡炎症与肺纤维化程度与正常组相比差异均有显著性(P<0.05);各组Ⅲ型胶原的表达也均高于正常组(P<0.05),且随着时间的延长呈进行性增加,在第28天达到高峰;该模型小鼠共死亡11只,死亡率为30.56%。结论在本实验中,以尾静脉一次性注射BLM 200 mg/(kg.bw)后第21天诱导建立的ICR小鼠肺纤维化模型成模最好,其小鼠死亡率低,操作简单,有效安全方便的特点使之有希望成为一种复制肺纤维化的理想模型。     

Molecular analysis of mitochondrial DNA mutations from bleomycin-treated rats

In our previous studies, we have shown the mutagenicity of bleomycin (BLM) at the nuclear hprt locus. In the present study we have analyzed mutagenic effects of BLM in mitochondrial DNA (mtDNA) using short extension-PCR (SE-PCR) method for detection of low-copy deletions. Fisher 344 rats were treated with a single dose of BLM and total DNA preparations from splenic lymphocytes were processed in SE-PCR assay. Spontaneous deletions were typically flanked by direct repeats (78.5%), while the in BLM-treated group, direct repeats were found in only 46.6% of breakpoints. The ratio between deletions based on direct repeats and random sequence deletions changed from 3.67 in control group to 0.87 in BLM-treated animals, which corresponds to an approximate 1.7-fold increase in the deletion mutation frequency. Furthermore, 62.5% of deletions not flanked by direct repeats in the treated group contained cleavage sites for BLM. The localization of breakpoints was not entirely random. We have found four clusters containing deletions from both groups indicative of deletion hot spots. The results indicate that BLM exposure may be associated with the induction of mtDNA mutations, and suggest the utility of SE-PCR method for evaluating drug-induced genotoxicity.     

Antioxidant activity in alveolar epithelial type 2 cells of rats during the development of bleomycin injury

Bleomycin (BLM) induces lung inflammation and subsequent fibrosis in human and in animal models. Alveolar epithelial type 2 cells (T2 cells) are known to play a crucial role in the repair process after BLM injury. We hypothesized that resistance of T2 cells to BLM-damage was associated with an increase in their antioxidant system activity. We developed an animal model of lung lesions preceding fibrosis, using daily intraperitoneal administration of BLM (1.5 mg/day over 7 and 14 days). We observed a body weight stablization in BLM-treated rats from the third day. After 14 days of BLM treatment, the number of cells recovered by bronchoalveolar lavage was significantly increased (p<0.05), with a dramatic increase (p<0.01) in the percentage of neutrophils associated with a decrease in macrophage percentage (p<0.01). No evidence of fibrosis was seen by microscopic studies at this time. However, T2 cells in 14-day-treated rats were swollen with enlarged lamellar inclusion bodies. Biochemical study of freshly isolated T2 cells displayed a significant decrease of lactate dehydrogenase (LDH) released by these cells when isolated from 14-day-treated rats as compared with 7-day. By contrast, BLM induced an increase in superoxide dismutase (SOD) and glutathione peroxidase activities. Cell content of glutathione was decreased and -glutamyl transpeptidase activity was markedly increased. These results show that BLM induces changes in the antioxidant system of T2 cells, particularly in the glutathione system.     

经鼻滴入博莱霉素致小鼠肺纤维化模型的建立及其病理演变

目的经鼻快速滴入博莱霉素复制小鼠肺纤维化模型,观察肺纤维化模型小鼠的病理形态学改变及其羟脯氨酸含量变化,鉴定肺纤维化模型的成功建立。方法经鼻滴入博莱霉素建立小鼠肺纤维化模型。分别于造模第14天和第28天后,取肺组织行HE染色和天狼猩红染色,取心、肝、脾、肾、脑组织行HE染色,光镜下观察组织病理学变化;造模第28天后用样本碱水解法检测肺组织中羟脯氨酸（HYP）的含量。结果①肺组织病理形态学改变：造模第14天和第28天后模型组小鼠肺泡炎及纤维化程度均明显高于阴性对照组,并且在造模第28天后肺纤维化程度进一步加重;②肺组织中HYP含量：与阴性对照组比较,模型组显著升高（P〈0.05）。结论经鼻滴入博莱霉素可以成功复制小鼠肺纤维化模型,肺纤维化模型小鼠HYP含量升高。     

Effect of 0.25 ppm ozone exposure on pulmonary damage induced by bleomycin

To study the effect of ozone in a chronically damaged lung, we used a bleomycin (BLM) induced pulmonary fibrosis model. Both endotracheal instillation of BLM and O3 exposure both produce lung inflammation and fibrosis. Oxidative stress would be a common mechanism of damage for both BLM and O3. Our aim was to assess lung injury induced by 5 and 60 days of intermittent exposure to 0.25 ppm O3 in rats with bleomycin-induced pulmonary fibrosis. Thirty-day-old Sprague Dawley rats were endotracheally instilled with BLM (1 U/100 g body weight) and, 30 days later, exposed to 0.25 ppm 03 (0.25 ppm 4 h per day, 5 days a week). Histopatology controls were instilled with saline and breathing room air. Histopathological evaluation of lungs was done 5 and 60 days after O3 exposure. BLM-induced lung damage did not change after 60 days of intermittent O3 exposure. Five days of O3 exposure increased the mean score of BLM-induced pulmonary inflammation and fibrosis (p=0.06). Frequency of bronchopneumonia increased from 1/7 to 6/6 (p <0.001), suggesting that a short-term exposure to O3 in a previously damaged lung might be a risk factor for developing further lung injury.