Effects of a calmodulin inhibitor on bleomycin-induced lung inflammation in hamsters. Biochemical, morphometric, and bronchoalveolar lavage data.

Previous studies have shown that bleomycin-induced pulmonary fibrosis is accompanied by elevated levels of calcium and calmodulin, which are important in the regulation of many biologic processes. The authors have further extended these observations and assessed the effect of a calmodulin inhibitor, trifluoperazine, on bleomycin-induced lung damage with biochemical, morphometric, and bronchoalveolar lavage techniques. The cumulative mortality due to bleomycin was not significantly reduced in animals receiving trifluoperazine. Trifluoperazine had no apparent effect on lung levels of collagen and DNA elevated by bleomycin. However, morphometric studies showed that the volume density of the lesion, the volume of amorphous material and interstitial inflammation, and the number of monocytes within lesions were less in the lungs of bleomycin-treated hamsters receiving trifluoperazine daily. When compared with hamsters treated with bleomycin alone, animals treated with both bleomycin and trifluoperazine had significantly fewer lymphocytes in their bronchoalveolar lavage fluid. The data suggest that trifluoperazine reduced the acute inflammation which accompanies bleomycin pneumotoxicity but did not affect the subsequent development of pulmonary fibrosis. It has been postulated that the observed antiinflammatory action of trifluoperazine may be due to inhibition of calmodulin-dependent leukocyte functions.     

Abatement of bleomycin-induced increases in vascular permeability, inflammatory cell infiltration, and fibrotic lesions in hamster lungs by combined treatment with taurine and niacin.

BACKGROUND: The bleomycin (BL) hamster model of interstitial pulmonary fibrosis has been widely used to study the pathogenesis of interstitial pulmonary fibrosis and to screen potentially desirable antifibrotic agents. We have recently shown that taurine and niacin in combination, diminished BL-induced increases in lung lipid peroxidation and hydroxyproline content in hamsters. In the present study, we have evaluated the effects of taurine and niacin on the bronchoalveolar lavage (BAL) cells, and morphologic and morphometric features of the lung in the same model of pulmonary fibrosis. EXPERIMENTAL DESIGN: The hamsters were divided into 4 groups: saline; taurine + niacin + saline; BL; and taurine + niacin + BL. Treatment of taurine and niacin began 2 days before the first intratracheal instillation of saline or BL and thereafter daily throughout the study for taurine + niacin + saline and taurine + niacin + BL groups. Hamsters received BL or saline in three consecutive doses at weekly intervals by intratracheal route. Twenty days after the last intratracheal instillation, the hamsters were sacrificed for various studies. RESULTS: Combined treatment with taurine and niacin suppressed BL-induced inflammation and almost completely abrogated pulmonary fibrosis in hamsters. Two independent studies showed that taurine and niacin in combination significantly reduced BL-induced increases in bronchoalveolar inflammatory cell counts, protein content, and acid phosphatase activity. By both light and electron microscopy, the lungs of hamsters treated with BL and taurine and niacin had much fewer inflammatory cells, less epithelial necrosis and collagen deposition than hamsters treated with BL alone. CONCLUSIONS: The results of this investigation suggest that combined treatment with taurine and niacin is effective against the development of lung fibrosis in the BL-hamster model and offers a novel therapeutic modality in the prevention of the fibrotic processes.     

IL-10 inhibits inflammation but does not affect fibrosis in the pulmonary response to bleomycin

Bleomycin yields pulmonary injury characterized by inflammation that proceeds to fibrosis. The production of IL-10 by pulmonary macrophages is increased in the inflammation that accompanies bleomycin lung injury. In the present study, IL-10 deficient and wildtype mice received 0.075 units of bleomycin intratracheally at day 0 and were sacrificed at day 7 or day 14. At day 7, pulmonary inflammation was increased in IL-10-deficient mice as reflected by increased representation of CD3+ and CD4+ lymphocytes and GR-1+ pulmonary granulocytes in the bronchoalveolar lavage (BAL) fluid. Pulmonary interstitial CD80+ and CD86+ mononuclear cells were increased in situ. At day 14, mononuclear cell inflammation was comparable between groups but pulmonary eosinophils were increased in the wildtype. There was no difference in the degree of pulmonary fibrosis, as judged by histology or lung hydroxyproline content. Lung chemokine expression of MIP-1alpha/beta, MIP-2, and eotaxin was increased at days 7 and 14 with a trend towards increased MCP-1 expression at day 14. The findings suggest an immunomodulatory role for IL-10 in the inflammatory response but not in the pulmonary fibrosis yielded by bleomycin.     

Effect of IL-2-Bax, a novel interleukin-2-receptor-targeted chimeric protein, on bleomycin lung injury

The role of lymphocytes in the pathogenesis of lung fibrosis is not clear, but the weight of the evidence supports a pro-fibrotic effect for lymphocytes. The high-affinity interleukin-2 receptor (haIL-2R) is expressed on activated, but not quiescent, T lymphocytes. This selective expression of haIL-2R provides the basis for therapeutic strategies that target IL-2R-expressing cells. We hypothesized that elimination of activated lymphocytes by IL-2R-targeted chimeric proteins might ameliorate lung fibrosis. We investigated the effects of IL-2-Bax, a novel apoptosis-inducing IL-2R-targeted chimeric protein, on bleomycin-induced lung injury in mice. Treatment groups included (i) a single intratracheal instillation of bleomycin and twice-daily intraperitoneal injections of IL-2-Bax; (ii) intratracheal bleomycin and intraperitoneal IL-2-PE66(4Glu), an older-generation chimeric protein; (iii) intratracheal bleomycin/intraperitoneal PBS; (iv) intratracheal saline/intraperitoneal PBS. Lung injury was evaluated 14 days after intratracheal instillation by cell count in bronchoalveolar lavage (BAL) fluid, semi-quantitative and quantitative histomorphological measurements and by biochemical analysis of lung hydroxyproline. Bleomycin induced a BAL lymphocytosis that was significantly attenuated by IL-2-Bax and IL-2-PE66(4Glu). However, morphometric parameters and lung hydroxyproline were unaffected by the chimeric proteins. These results show that IL-2-Bax reduces the lymphocytic infiltration of the lungs in response to bleomycin, but this effect is not accompanied by a decrease in lung fibrosis.     

Ameliorating effect of an interferon inducer polyinosinic-polycytidylic acid on bleomycin-induced lung fibrosis in hamsters. Morphologic and biochemical evidence.

The effects of polyinosinic-polycytidylic acid (Poly I:C), an inducer of interferons, on bleomycin (Bleo)-induced lung fibrosis was studied in hamsters. Poly I:C (10 mg/kg intraperitoneally) was administered for two days and immediately before intratracheal instillation of bleomycin (7.5 U/kg) or an equivalent volume of saline and thereafter daily for 13 days. The lung hydroxyproline in control, Poly I:C, Bleo, and Bleo + Poly I:C groups averaged 791, 752, 1177, and 766 micrograms/lung. As compared to control, the prolyl hydroxylase activity in the Bleo group was increased by 83% whereas in Bleo + Poly I:C group, the activity was increased by 42%. Protein in the bronchoalveolar lavage supernatant in Poly I:C, Bleo and Bleo + Poly I:C groups were 72, 286, and 206% of the control, respectively. There was no difference in total leukocyte counts between Bleo + Poly I:C and Bleo groups, but the differential cell counts were changed. The numbers of neutrophils, monocytes, lymphocytes, and eosinophils were 50, 84, 91, and 10% of Bleo group, respectively. Morphometric estimates of the volume of parenchymal lesion within the lung showed that hamsters in Bleo + Poly I:C group had significantly less volume of lesion (1.0 cucm) than the Bleo group (1.6 cucm). In addition, the fibrotic lesions in Bleo + Poly I:C group were multifocal and primarily proximal acinar in location, had fewer extracellular fibers, neutrophils and monocytes. Poly I:C treatment ameliorated bleomycin-induced lung collagen accumulation.     

Analysis of bronchoalveolar lavage fluid from bleomycin-induced pulmonary fibrosis in hamsters

The purpose of this study was to analyze the cellular and noncellular components of bronchoalveolar lavage fluid (BALF) at varying times during the development of pulmonary fibrosis induced by bleomycin. Hamsters were killed and lavaged in situ following the administration of a single intratracheal injection of 1 unit of bleomycin or an equivalent volume of sterile isotonic saline. The results show that the total cell counts in the BALF of bleomycin-treated hamsters, as compared with controls, were increased 7.7, 4.4, 2.4, 1.6, and 1.9-fold at 2, 4, 7, 14, and 21 days after treatment, respectively. The predominant cell types in the BALF of control animals were macrophages which constituted 84% of the total cells, followed by lymphocytes, 11%. The predominant cell types in the BALF of bleomycin-treated animals were polymorphonuclear leukocytes (PMN) which constituted 65% at two days and approximately 50% of the total at 4, 7, and 14 days; at 21 days macrophages were the predominant cell type constituting 50%, followed by lymphocytes at 30%. However, the total number of lymphocytes was not increased at 21 days compared to previous times. The noncellular protein content of BALF from bleomycin-treated hamsters, an index of pulmonary vascular permeability, was increased to 224, 559, 637, and 270% of control (2.7 mg/lung) at 2, 4, 7, and 14 days after treatment, respectively, and returned to control levels at 21 days. The acid phosphatase activity in the supernatant of BALF of bleomycin-treated animals was significantly increased to 181, 181, 199, 176, and 125% of control (258 units/lung) at 2, 4, 7, 14, and 21 days, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

Increased expression of HLA-DR antigen on alveolar macrophages in pulmonary diseases

Summary The expression of HLA-DR antigen on alveolar macrophages obtained by bronchoalveolar lavage in healthy controls and patients with different diseases was investigated, using cytofluorographic analysis and phykoerythrin conjugated monoclonal mouse anti-human HLA-DR antibody. Alveolar macrophages in patients with extrinsic allergic alveolitis (n=4), idiopathic lung fibrosis (n=4), sarcoidosis (n=6), rheumatoid lung disease (n=6) and pulmonary infection (n=5) showed increased density of HLA-DR antigen expression compared to healthy control subjects (n=5). The increased expression of HLA-DR antigen on alveolar macrophages confirms the importance of these cells for recognition of antigens and immunological responses in different pulmonary diseases.Abbreviations BAL bronchoalveolar lavage - PBS phosphate buffered saline     

肺巨噬细胞在小鼠肺纤维化发生中的作用

本文以博莱霉素注入小鼠气管内诱发肺泡炎导致肺纤维化。对肺泡灌洗液（ＢＡＬ）内细胞进行分类，检测了ＢＡＬ中及肺泡巨噬细胞（ＰＭ）培养上清液内酸性酶活性，并检测了ＰＭ培养上清液对成纤维增殖的影响。结果表明，实验组ＢＡＬ中ＰＭ数增加，酸性酸酶活性上升，并与肺胶原蛋白含量相关，ＰＭ培养上清使肺成纤维细胞＾３Ｈ－Ｔdisplay status     

Poly(ADP-ribose) synthetase activity during bleomycin-induced lung fibrosis in hamsters

Bleomycin damages cellular DNA and is a potent inducer of pulmonary fibrosis. It has been shown to act through a superoxide-mediated mechanism. We are interested in determining the biochemical mechanisms involved in fibrosis and in this preliminary study we have examined the temporal relationship between early biochemical events associated with DNA damage and fibrosis, in lungs of hamsters after administration of 0.75 unit of bleomycin. The activities of poly(ADP-ribose) synthetase, an enzyme associated with DNA repair, inducible superoxide dismutase (SOD) and prolyl hydroxylase as well as the tissue levels of NAD+ and hydroxyproline in the lung were determined. All three enzyme activities expressed as per milligram DNA or per lung, increased upon bleomycin treatment over the saline-administered controls. Lung poly(ADP-ribose) synthetase activity which is sensitive to DNA breaks, increased first (24% over control in 1 day, P less than 0.0001), attained the maximum value on the 5th day (952% over control, P less than 0.0001), and started to decline thereafter and approached near the control value on 14th day. Bleomycin treatment induced a rapid change in the level of lung NAD+. After 1 day the level of NAD+ was reduced by 42% compared to the control (P less than 0.001), further declined to 65% (P less than 0.001) on the 3rd day, and stayed at that level until the 7th day. On the 14th day, however, the NAD+ level was still lower (29%, P less than 0.05) but approaching the value in the control animals. The activity of prolyl hydroxylase showed significant increase on the 3rd day (50% over control, P less than 0.0001) after bleomycin administration. The enzyme activity continued to increase until the end of the experiment (490% of control, P less than 0.0001, on Day 14). The content of undialyzable hydroxyproline, a marker for collagen, was also increased significantly in the lung tissue on the 3rd day (30% over control, P less than 0.05), continued to increase and reached the highest level on the 14th day (71% over control, P less than 0.001). A significant increase in the activity of SOD (19% over control, P less than 0.001) was seen on the 5th day which continued to increase and attained the highest value on Day 14 (115% over control, P less than 0.0001).(ABSTRACT TRUNCATED AT 400 WORDS)     

Heparin attenuates bleomycin but not silica-induced pulmonary fibrosis in mice: possible relationship with involvement of myofibroblasts in bleomycin, and fibroblasts in silica-induced fibrosis

Pulmonary fibrosis was elicited in mice or rats by the intra-tracheal instillation of bleomycin or silica. Daily injections of heparin significantly reduced the collagen deposition in bleomycin, but not in silica, injected mice, as evaluated by the lung hydroxyproline content on day 15 after instillation. Heparin also reduced the bleomycin-induced morbidity and mortality. Study of the broncho-alveolar lavage fluid (BAL) detected no significant change in the number of leucocytes or the amount of protein in heparin treated mice. Histologies of bleomycin instilled mice suggested that heparin did reduce the alveolar remodelling but not the alveolitis, evidenced by leucocytic infiltration. As detected by electron microscopy (EM), bleomycin increased the number of leucocytes and platelets within the alveolar capillaries but this was not significantly reduced by heparin. The phenotype of the interstitial cell involved in these two types of pulmonary fibrosis was investigated by immunohistochemistry and EM. While in bleomycin injected animals the interstitial cells had the phenotype of an actin (α-actin in the rat) and lipid containing interstitial cell, with a poorly developed RE, in silica injected animals in contrast, the interstitial cells were without cytoplasmic actin or lipid but with a markedly developed endoplasmic reticulum (ER). Thus bleomycin and silica induced the growth of two different types of interstitial cells, the myofibroblast and the regular fibroblast, which might be a reason why heparin selectively inhibits bleomycin but not silica-induced fibrosis.     

Mice lacking neutrophil elastase are resistant to bleomycin-induced pulmonary fibrosis

Neutrophil elastase is a serine protease stored in the azurophilic granules of leukocytes. It has been implicated in the pathology of several lung diseases and is generally presumed to contribute to the tissue destruction and extracellular matrix damage associated with these conditions. To delineate the role of neutrophil elastase in pulmonary inflammation and fibrosis, neutrophil elastase-null mice were intratracheally instilled with bleomycin. In neutrophil elastase-null mice, biochemical and morphological characteristics of pulmonary fibrosis were attenuated for at least 60 days after bleomycin administration despite a typical response to bleomycin as evidenced by assessment of indices of DNA and cell damage. Neutrophil burden of bleomycin-treated wild-type and neutrophil elastase-null mice was comparable, and marked neutrophilic alveolitis was manifest in bleomycin-treated neutrophil elastase-null mice. An absence of immunostaining for active transforming growth factor (TGF)-beta in lung tissue from bleomycin-treated neutrophil elastase-null mice suggested a defect in TGF-beta activation, which was confirmed by biochemical assessment of TGF-beta levels in bronchoalveolar lavage fluid and lung tissue. These data point to novel and unexpected fibrogenic consequences of neutrophil elastase activity in the inflamed lung.     

The effect of alpha-difluoromethylornithine on the development of bleomycin-induced pulmonary fibrosis in hamsters.

The development of bleomycin-induced lung fibrosis was studied in hamsters drinking tap water or 2% alpha-difluoromethylornithine (DFMO) dissolved in tap water for 14 days. The fibrotic lesions in the lung were evaluated by biochemical measurements of total neutral salt soluble (NSS) and insoluble (NSI) collagens and by morphometric histopathologic techniques. Daily ingestion of DFMO failed to offer any protection against bleomycin-induced lung fibrosis; instead, it increased the deposition of total lung NSI collagen to 396% of control, as compared with 145% of control caused by bleomycin treatment alone. Daily intake of DFMO by itself increased the accumulation of total lung NSI collagen to 250% of control, as opposed to a 145% increase caused by bleomycin treatment alone. Histopathologically, the lung lesions in hamsters treated with bleomycin and DFMO were qualitatively similar to those of hamsters treated with bleomycin alone. However, morphometric estimates revealed that of lung lesions were more diffuse and severe in the former than in the latter group.     

Extracellular matrix powder protects against bleomycin-induced pulmonary fibrosis

Pulmonary fibrosis refers to a group of lung diseases characterized by inflammation, fibroblast proliferation, and excessive collagen deposition. Although the mechanisms underlying pulmonary fibrosis are poorly understood, current evidence suggests that epithelial injury contributes to the development of fibrosis. Regenerative medicine approaches using extracellular matrix (ECM) scaffolds have been shown to promote site-specific tissue remodeling. This led to the hypothesis that particulate ECM would promote normal tissue repair and attenuate bleomycin-induced pulmonary fibrosis. C57BL/6 mice were treated intratracheally with bleomycin or saline with or without a particulate form of ECM scaffold from porcine urinary bladder matrix (UBM-ECM) or enzymatically digested UBM-ECM. Mice were sacrificed 5 and 14 days after exposure. Compared to control mice, bleomycin-exposed mice had similar increases in inflammation in the bronchoalveolar lavage fluid regardless of UBM-ECM treatment. However, 14 days after exposure, lung histology and collagen levels revealed that mice treated with bleomycin and the particulate or digested UBM-ECM had negligible fibrosis, whereas mice given only bleomycin had marked fibrosis. Administration of the particulate UBM-ECM 24 h after bleomycin exposure also significantly protected against pulmonary injury. In vitro epithelial cell migration and wound healing assays revealed that particulate UBM-ECM promoted epithelial cell chemotaxis and migration. This suggests that promotion of epithelial wound repair may be one mechanism in which UBM-ECM limits pulmonary fibrosis.     

Time course of bleomycin-induced lung fibrosis

Intratracheal instillation (IT) of bleomycin is a widely used experimental model for lung fibrosis. In this study we describe the time-course of bleomycin-induced lung fibrosis in mice using computer-assisted morphometry. C57Bl/6J mice were treated with a single IT dose of bleomycin or control saline. Animals were killed 3, 6, 14 and 21 days post-IT. Lung injury was evaluated by analysis of bronchoalveolar lavage (BAL) fluid, hydroxyproline concentration in the lung, routine light microscopic examination resulting in a semiquantitative morphological index (SMI) of lung injury, and quantitative morphological measurements (fibrosis fraction and alveolar wall area fraction) aided by optimas image analysis software. Changes in BAL fluid attributed to bleomycin treatment include increased total cell count (days 14 and 21), and increased percentage of neutrophils (days 3 and 6) followed by a sustained increase in lymphocytes (days 6, 14 and 21). Hydroxyproline levels increased in bleomycin-treated mice on days 14 and 21. Median SMI grades were significantly elevated on days 3, 14 and 21. Computer-assisted morphometry demonstrated a 3-fold increase in fibrosis fraction and a 1.3-fold increase in wall area fraction in bleomycin-treated mice on day 14, with no further increase on day 21. These data also demonstrate that the most suitable time point for assessing lung fibrosis in this model is 14 days after IT instillation of bleomycin, based on the observation that at 14 days the animals developed extensive fibrosis, but had less variability in the fibrotic response and lower mortality than later at 21 days. Computer-assisted morphometry provides objective and quantitative measurements that are a useful tool for the evaluation of bleomycin-induced lung injury.     

Abnormalities of pathways of fibrin turnover in lung lavage of rats with oleic acid and bleomycin-induced lung injury support alveolar fibrin deposition.

Alveolar fibrin deposition commonly accompanies acute lung injury, but the nature of the local abnormalities of coagulation and fibrinolysis that support pathologic fibrin deposition are not well understood. The trended abnormalities of procoagulant and fibrinolytic activities occurring in lung lavage fluids of Fischer 344 rats after lung injury induced by intravenous oleic acid (OA) or intratracheal bleomycin were studied. After injury by either agent, bronchoalveolar lavage (BAL) contained increased procoagulant activity and decreased fibrinolytic activity. Lavage procoagulant activity was mainly due to an activator of Factor X attributable to the extrinsic coagulation pathway, and fibrinolytic activity was almost completely plasminogen dependent. Major mechanisms of inhibition of fibrinolytic activity involved both the inhibition of the plasminogen activator (PA) and plasmin. These abnormalities were temporally associated with prominent alveolar fibrin deposition in both models. In OA-treated animals, lavage fibrinolytic activity was absent or profoundly decreased, and antiplasmin and procoagulant activities were increased within 4 hours after the induction of acute lung injury. By 24 hours after OA, lavage PA inhibitor (PAI) activity was elevated with sustained antiplasmin activity. By 3 days after OA, these abnormalities had resolved in association with almost complete resolution of alveolar fibrin deposits. Within 3 days after bleomycin-induced lung injury, lavage procoagulant activity was increased and fibrinolytic activity was depressed due to increased antiplasmin and PAI activities. These conditions persisted for 2 weeks, during which time alveolar fibrin deposition was associated with the development of pulmonary fibrosis. These data indicate that a disruption of the normal balance between procoagulant and fibrinolytic activities occurs in alveolar lining fluids of rats with alveolitis induced by either OA or bleomycin, and that concurrent abnormalities of pathways of fibrin turnover that occur in alveolar lining fluids promote the alveolar fibrin deposition associated with these lung injuries.     

Biochemical and structural alterations of hamster lungs in response to intratracheal administration of bleomycin

One unit of bleomycin was administered intratracheally to hamsters and an equivalent volume of saline to controls. Morphological changes within lungs of bleomycin-treated hamsters consisted of a diffuse hemorrhagic interstitial pneumonia at 7 days post-treatment. Lungs contained less hemorrhage and edema but increased numbers of mononuclear inflammatory cells and thickened interalveolar walls at 14 days post-treatment. A diffuse mononuclear cell infiltrate with multifocal areas of fibrosis later predominated. The protein, RNA, and DNA levels in bleomycin-treated hamsters were consistently and significantly elevated at 4 (except DNA), 7, 14, 21, and 28 days after treatment. The Ca²⁺ levels in lungs of these animals at the corresponding times were increased by 158, 194, 36, 22, and 8% without any change in plasma Ca²⁺. Lung soluble collagen was increased by 124, 207, 121, and 30% at 7, 14, 21, and 28 days, respectively, after bleomycin treatment. The increases in insoluble collagen were 65, 108, 132, and 91% at the corresponding times. The lung cAMP levels at 4, 7, 14, 21, and 28 days were 176, 164, 132, 158, and 96% of control, respectively, and cGMP at the corresponding times were 50, 81, 222, 198, and 137% of control. These data suggest that shifts in the intracellular levels of cAMP, cGMP, and Ca²⁺ are associated with early lung changes induced by bleomycin insult and may serve as indicators to gauge the severity and progression of lung damage.     

Bleomycin-stimulated hamster alveolar macrophages release interleukin-1.

The capacity of alveolar macrophages (AM) of bleomycin-instilled hamsters to proliferate mouse thymocytes (interleukin-1 activity) and hamster fibroblasts (fibroblast proliferation (FP) activity was studied. Using bleomycin-instilled hamsters, the FP activity of AM culture supernatants was increased significantly on days 1, 5, and 10 after instillation of bleomycin. The interleukin-1 (IL-1) activity, however, was increased significantly on day 1 only as compared with saline-treated hamsters. Next, normal AM were stimulated in vitro by bleomycin. After being fractionated by chromatography, their culture supernatant showed IL-1 activity, which also indicated FP activity. These results suggest that bleomycin directly stimulates AM to release IL-1 in the fibrogenic responses.     

人脐带间充质干细胞对新生鼠肺纤维化的防治作用**

背景：间充质干细胞因具有自我增殖、多向分化潜能和旁分泌等功能,成为慢性肺部疾病细胞替代治疗的研究热点。 目的：探讨人脐带间充质干细胞对新生大鼠肺纤维化的防治作用及对正常肺发育的影响。 方法：将32只新生2 d SD大鼠随机数字表法均分为PBS对照组、人脐带间充质干细胞组、博来霉素对照组,博来霉素+人脐带间充质干细胞组,后两组腹腔注射博来霉素建立肺纤维化模型,2个细胞组于第7天腹腔注射人脐带间充质干细胞。 结果与结论：博来霉素对照组羟脯氨酸水平最高,肺纤维化最严重,与其他3组比较差异均有显著性意义(P < 0.05);博来霉素干预的两组辐射状肺泡计数和肺组织匀浆中的转化生长因子β1 mRNA表达均低于其他两组(P < 0.05),但血管内皮生长因子mRNA表达升高(P < 0.05),给予细胞治疗后,上述指标均有好转(P < 0.05)。说明人脐带间充质干细胞能过旁分泌增加血管内皮生长因子mRNA表达,下调转化生长因子β1 mRNA水平,对肺纤维化起保护作用。另外,正常鼠腹腔注射脐带间充质干细胞后辐射状肺泡计算无明显变化,证实其对新生鼠肺发育无明显影响。      

Repeated exposures to enzyme-generated oxidants cause alveolitis, epithelial hyperplasia, and fibrosis in hamsters.

Oxidant-mediated epithelial injury and repair processes may promote the development of pulmonary fibrosis. The authors examined this hypothesis by inducing oxidant injury in hamsters with intratracheally instilled mixtures of glucose, glucose oxidase (GO) and lactoperoxidase at weekly intervals. Solutions containing denatured GO (DE) served as a control treatment. One and six days after each treatment, anesthetized animals were sacrificed and lavaged, and their lungs and plasma were preserved for further study. Although DE-treatment consistently evoked a transient, neutrophil-rich inflammatory response, no significant biochemical or morphologic changes were detected at the ensuing 6-day time points. In contrast, repeated GO treatments prolonged inflammation and injured the alveolar epithelium, evidenced by significantly greater levels of neutrophils and macrophages in bronchoalveolar lavage fluid (BALF) and increased BALF levels of protein, beta-glucuronidase and lactic dehydrogenase activities. Active GO also altered BALF lymphocytes and monocytes, but no discernable pattern emerged. Fibrotic, consolidated parenchyma appeared after the second and third GO exposures, coinciding with increased levels of total collagen, prolyl hydroxylase activity, and anti-oxidant enzyme activities. Although alveolitis and type II cell hyperplasia were observed after the initial treatment, polyplike nodules covered by hyperplastic, undifferentiated epithelium were evident after the third treatment. After each exposure, GO-treated animals had larger volumes of parenchymal lesion than DE-treated hamsters. These data indicate that normal alveolar epithelial repair processes were greatly disrupted by repeated oxidant injury and suggest that repeated and/or continued epithelial injury may contribute to the development of pulmonary fibrosis.