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)     

Effects of three cysteine pro-drugs on bleomycin-induced lung fibrosis in hamsters.

The cysteine pro-drug Z2196 ((2RS, 4R)-2-methylthiazolidine carboxylic acid) and two drugs with methyl esters attached to Z2196 (Z2197 and Z2199) were evaluated for antifibrotic effects in the hamster bleomycin model of lung fibrosis. Each drug or phosphate-buffered saline (PBS) was given daily (300 mg/kg intraperitoneally) for 2 days before intratracheal instillation of bleomycin (7.5 units/kg) or saline for an additional 13 days. Lung collagen measured as hydroxyproline was significantly increased to 138% of the control groups in the PBS + Bleomycin treated group, but the Z2196 + Bleomycin group was increased to 108% and was not statistically different from controls. Protein content of bronchoalveolar lavage supernatant in PBS + Bleomycin treated hamsters was significantly increased to 326% of controls. The protein content of bronchoalveolar lavage supernatant for all cysteine pro-drug + Bleomycin treated hamsters was increased to 160% of PBS + Bleomycin treated hamsters. All the Bleomycin treated hamsters had significantly more cells and more neutrophils recovered in bronchoalveolar lavage than controls. The PBS + Bleomycin treated hamsters had significantly more lymphocytes in bronchoalveolar lavage than all the other treatment groups. The Z2196 + Bleomycin and Z2197 + Bleomycin hamsters had significantly less monocytes in BALF than PBS + Bleomycin hamsters. The lung total sulfhydryl and nonprotein sulfhydryl in PBS + Bleomycin treated hamsters were increased to 210% and 253% of controls, respectively, whereas in Z2196 + Bleomycin hamsters they were increased to 152% and 153%, respectively. Histopathology of PBS + Bleomycin hamsters showed a diffuse mixed mononuclear alveolitis, multifocal fibrosis and peribronchiolar fibrosis, whereas Z2196 + Bleomycin hamsters showed notably less alveolitis and fibrosis.(ABSTRACT TRUNCATED AT 250 WORDS)     

Extracellular superoxide dismutase in pulmonary fibrosis

Disruption of the oxidant/antioxidant balance in the lung is thought to be a key step in the development of many airway pathologies. Hence, antioxidant enzymes play key roles in controlling or preventing pulmonary diseases related to oxidative stress. The superoxide dismutases (SOD) are a family of enzymes that play a pivotal role protecting tissues from damage by oxidant stress by scavenging superoxide anion, which prevents the formation of other more potent oxidants such as peroxynitrite and hydroxyl radical. Extracellular SOD (EC-SOD) is found predominantly in the extracellular matrix of tissues and is ideally situated to prevent cell and tissue damage initiated by extracellularly produced ROS. EC-SOD has been shown to be protective in several models of interstitial lung disease, including pulmonary fibrosis. In addition, alterations in EC-SOD expression are also present in human idiopathic pulmonary fibrosis (IPF). This review discusses EC-SOD regulation in response to pulmonary fibrosis in animals and humans and reviews possible mechanisms by which EC-SOD may protect against 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.     

Progress of bleomycin-induced lung fibrosis in rabbits

Progression of lung fibrosis induced in rabbits by intratracheal bleomycin (BLM, 10 mg/kg) was monitored by biochemical and morphological measurements. These indicated that the evolution of fibrosis in the rabbit was slower than in other experimental animals. Histology revealed cellular and fibrocellular lesions 4 weeks after BLM. At 8 weeks these lesions still predominated, indicating continuing active disease accompanied by a progression to fibrosis. The gradual progression of the response was reflected in alterations in lung composition. Changes in lung content of collagen, protein and DNA were evident at 8 weeks after BLM, at which time concentration (micrograms/mg dry weight) of collagen and protein were also elevated (P less than 0.05). Plasma angiotensin converting enzyme (ACE), a marker of endothelial injury, decreased 1 week after BLM (P less than 0.01) and then returned to normal, indicating that endothelial injury does not parallel the fibrotic response. In summary, the continuing active inflammation and slow progress of fibrosis induced by i.t. BLM in the rabbit suggests that this model has advantages over others for the serial study of the cellular and biochemical evolution of lung fibrosis.     

依那西普抑制博来霉素诱导的小鼠肺纤维化

 目的：观察肿瘤坏死因子 α(TNF-α)拮抗剂依那西普对博来霉素诱导的肺纤维化小鼠的抑制纤维化作用,并探讨依那西普治疗肺纤维化的可能机制。方法：将45只SPF级雌性昆明小鼠随机分为3组：对照组（气管内雾化生理盐水）、纤维化组（气管内博来霉素3 mg/kg溶于100 μL生理盐水内雾化）和依那西普干预组（气管内雾化博来霉素后,4 mg/kg依那西普溶于100 μL生理盐水内腹腔注射,每3 d注射1次）。处理后第28 d收集样本,小鼠左肺置于10%中性甲醛固定,石蜡包埋切片后行HE与Masson染色;右肺碱水解法检测组织羟脯氨酸(HYP)的含量;酶联免疫法检测血清TNF-α和转化生长因子 β（TGF-β）的含量;提取肺组织总蛋白,Western blotting 检测磷酸化ERK1/2、JNK和p38的表达。结果：依那西普干预组肺组织病理损伤及气道上皮下胶原沉积较纤维化组减轻,肺叶炎症损伤评分和纤维化评分明显下降（均P<0.01）,肺组织HYP含量显著降低（P<0.05）,血清TNF-α 和TGF-β的浓度明显减少（均P<0.01）,肺组织ERK1/2、JNK和p38蛋白的磷酸化水平也显著下降（P<0.01,P<0.05,P<0.01）。结论：依那西普能显著下调TNF-α 和TGF-β的水平,从而抑制ERK1/2、JNK和p38的活化,缓解博来霉素诱导的小鼠肺纤维化病变。     

Morphometric estimates of infiltrative cellular changes during the development of bleomycin-induced pulmonary fibrosis in hamsters

The sequence of cellular infiltration into interstitial lung tissue subsequent to intratracheal administration of bleomycin was examined in hamsters. Quantitation of lesions following bleomycin treatment showed a transient increase in the percentage of lung involved, which peaked at 21 days and decreased thereafter. Associated with these lesions was a significant increase in interstitial cell profile density at 21 and 28 days. The total number of cell profiles decreased after 28 days. The cellular composition of the lesion was dominated by monocytes, neutrophils, and macrophages in the initial phase of the fibrosis. Subsequently, monocytes were significantly decreased at 21, 28, and 42 days, as compared with the 7-day value. Similarly, neutrophils were significantly decreased at 21 and 28 days, as compared with the 7-day value. In contrast, macrophages were significantly decreased in the initial phase (7 days) of the cellular infiltration and the later phase at 35 and 42 days, as compared with the value at 4 days after treatment. Lesion composition in the later phase exhibited significant increases in fibroblasts and eosinophils, accompanied by a general increase in lymphocytes. It is concluded that bleomycin-induced inflammatory sequela exhibits temporally based changes in cellular composition of the infiltrate and that the temporal changes in cellularity might be one of the determinants in the pathophysiology of pulmonary fibrosis induced by bleomycin.     

吉非替尼抑制博莱霉素诱导的小鼠肺纤维化

目的:观察吉非替尼对博莱霉素诱导的小鼠肺纤维化的抑制作用。方法:将40只SPF级雌性BALB/c小鼠分为4组:对照组(气管滴入生理盐水)、单纯口服吉非替尼组(吉非替尼灌胃200 mg/kg)、纤维化组(气管滴入博莱霉素3 mg/kg)、纤维化吉非替尼干预组(气管滴入博莱霉素+吉非替尼灌胃20 mg/kg)。实验第14 d杀鼠取肺,左肺石蜡切片行HE染色与Masson染色,免疫组化检测总表皮生长因子受体(EGFR)及磷酸化EG-FR;取右肺检测羟脯氨酸含量。结果:纤维化吉非替尼干预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(P0.05),气道上皮及肺间质细胞磷酸化EGFR表达评分下降(P0.05)。单纯口服吉非替尼组小鼠气道上皮下未见明显胶原沉积,肺羟脯氨酸含量及磷酸化EGFR表达评分与对照组相比无显著差异(P0.05)。结论:吉非替尼灌胃能显著抑制博莱霉素诱导的小鼠肺纤维化,大剂量(200 mg/kg)吉非替尼灌胃未引起明显肺纤维化。     

Collagenase and gelatinase activities in bronchoalveolar lavage fluids during bleomycin-induced lung injury

Basement membrane degradation can be indicative of tissue injury, but the process may also release matrix-bound cytokines to stimulate cell regeneration. To investigate this process, acute lung injury was induced in rats by intratracheal bleomycin and animals were killed from 3 days to 8 weeks later. The lungs were lavaged with saline to collect bronchoalveolar lavage (BAL) fluid and cell proliferation was assessed by pulse incorporation of tritiated thymidine. Bleomycin induced rapid inflammation with increased cell numbers and protein levels in BAL. Collagen degradation products were also increased in BAL fluid from 3 days to 4 weeks. Incubating samples of BAL fluid with radiolabelled collagens I and IV showed that high levels of activity, particularly for the degradation of type IV collagen, were present as early as 3 days post-bleomycin and persisted over the 8-week period. Zymograms demonstrated the highest level of gelatinase A (MMP-2) activity in BAL fluid in the first 2 weeks after bleomycin. Coincident with peak basement membrane degradative activity was the onset of a phase of epithelial cell proliferation, as measured by labelled nuclei in autoradiographs. The results show that enzymes capable of degrading the alveolar basement membrane are secreted early in the lung injury phase and that their presence in BAL fluid can be used as a measure of alveolar wall damage. It is possible that this enzyme action may release bound cytokines from the basement membrane, since maximal gelatinase activity correlates with alveolar epithelial cell proliferation. © 1998 John Wiley & Sons, Ltd.     

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)     

Progress of bleomycin-induced lung fibrosis in rabbits.

Progression of lung fibrosis induced in rabbits by intratracheal bleomycin (BLM, 10 mg/kg) was monitored by biochemical and morphological measurements. These indicated that the evolution of fibrosis in the rabbit was slower than in other experimental animals. Histology revealed cellular and fibrocellular lesions 4 weeks after BLM. At 8 weeks these lesions still predominated, indicating continuing active disease accompanied by a progression to fibrosis. The gradual progression of the response was reflected in alterations in lung composition. Changes in lung content of collagen, protein and DNA were evident at 8 weeks after BLM, at which time concentration (micrograms/mg dry weight) of collagen and protein were also elevated (P less than 0.05). Plasma angiotensin converting enzyme (ACE), a marker of endothelial injury, decreased 1 week after BLM (P less than 0.01) and then returned to normal, indicating that endothelial injury does not parallel the fibrotic response. In summary, the continuing active inflammation and slow progress of fibrosis induced by i.t. BLM in the rabbit suggests that this model has advantages over others for the serial study of the cellular and biochemical evolution of lung fibrosis.     

Liver procollagen prolyl hydroxylase in Opisthorchis viverrini infected hamsters after praziquantel administration

Infection of hamsters by the human liver fluke Opisthorchis viverrini elevated liver procollagen prolyl hydroxylase activity, reflecting increased collagen biosynthesis. The increase was proportional to the intensity of infection. However, the infected liver procollagen prolyl hydroxylase activity decreased after administration of praziquantel 300 mg kg^?1 body weight, and approached normal levels two weeks after treatment. In the infected hamsters, praziquantel, at a curative dose, caused a transient increase in serum aminotransferase levels and a small but persistent rise in serum alkaline phosphatase. The drug, however, did not cause changes in these enzyme activities in the uninfected hamsters.     

SPARC oppositely regulates inflammation and fibrosis in bleomycin-induced lung damage

Fibrosis results from inflammatory tissue damage and impaired regeneration. In the context of bleomycin-induced pulmonary fibrosis, we demonstrated that the matricellular protein termed secreted protein acidic and rich in cysteine (SPARC) distinctly regulates inflammation and collagen deposition, depending on its cellular origin. Reciprocal Sparc(-/-) and wild-type (WT) bone marrow chimeras revealed that SPARC expression in host fibroblasts is required and sufficient to induce collagen fibrosis in a proper inflammatory environment. Accordingly, Sparc(-/-) >WT chimeras showed exacerbated inflammation and fibrosis due to the inability of Sparc(-/-) macrophages to down-regulate tumor necrosis factor production because of impaired responses to tumor growth factor-β. Hence, the use of bone marrow cells expressing a dominant-negative form of tumor growth factor-β receptor type II under the monocyte-specific CD68 promoter, as a decoy, phenocopied Sparc(-/-) donor chimeras. Our results point to an unexpected dual role of SPARC in oppositely influencing the outcome of fibrosis.     

Changes in mucosal superoxide dismutase activities of gastric lesions

The mucosal superoxide dismutase (SOD) activities were serially examined on the acute gastric mucosal lesion (AGML) induced by water-immersion restraint stress to rats for six hours. The mucosal SOD activities gradually increased in proportion to the time up to 3 hours after the restraint stress. But it decreased 6 hours after when severe damage had been established in the mucosa. On the other hand, the mucosal SOD activities of the margins of human gastric ulcer showed to be higher on the healing stage than on the active stage. And the SOD activities of the intractable ulcer were lower than those of the curable ulcer. These results indicate that the mucosal SOD may play some important roles both on the protecting process information of AGML and on the healing process in gastric ulcer.     

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.     

Thrombin-activatable fibrinolysis inhibitor deficiency attenuates bleomycin-induced lung fibrosis

Decreased fibrinolytic function favors the development of pulmonary fibrosis. Thrombin-activatable fibrinolysis inhibitor (TAFI) is a strong suppressor of fibrinolysis, but its role in lung fibrosis is unknown. Therefore, we compared bleomycin-induced lung fibrosis in TAFI-deficient, heterozygous, and wild-type mice. The animals were sacrificed 21 days after bleomycin administration, and markers of lung fibrosis and inflammation were measured. The bronchoalveolar lavage fluid levels of total protein, neutrophil proteases (elastase, myeloperoxidase), cytokines (tumor necrosis factor-alpha, interleukin-13), chemokine (monocyte chemoattractant protein-1), coagulation activation marker (thrombin-antithrombin complex), total soluble collagen, and growth factors (platelet-derived growth factor, transforming growth factor-beta1, granulocytic-macrophage growth factor) were significantly decreased in knockout mice compared to wild-type mice. Further, histological findings of fibrosis, fibrin deposition, and hydroxyproline and collagen content in the lung were significantly decreased in knockout mice compared to wild-type mice. Depletion of fibrinogen by ancrod treatment led to equalization in the amount of fibrosis and collagen deposition in the lungs of knockout and wild-type mice. No difference was detected in body temperature or arterial pressure between the different mouse phenotypes. These results suggest that the anti-fibrinolytic activity of TAFI promotes lung fibrosis by hindering the rate at which fibrin is degraded.     

Thrombin enhances lung fibroblast proliferation in bleomycin-induced pulmonary fibrosis.

To clarify the role of thrombin in fibroblast growth and the development of pulmonary fibrosis in bleomycin-induced interstitial lung disease, we examined the relationship of thrombin activity to fibroblast growth-stimulating activity (FGA) in bronchoalveolar lavage (BAL) fluid from bleomycin-treated rats. Male Wistar rats were given a single intratracheal injection of bleomycin, BAL was performed 2, 6, and 15 days later, and the BAL fluid was assayed for thrombin activity and FGA. Higher FGA than the control value was detected in the BAL fluid from rats on day 6 after bleomycin administration. In bleomycin-treated rats, thrombin activity in the BAL fluid was significantly elevated on day 2 and maximal on day 6. The FGA of the BAL fluid from bleomycin-treated rats on day 6 was significantly decreased by its treatment with various thrombin inhibitors, such as alpha 1-protease inhibitor, antithrombin III, hirudin, and MD-805. In our assay, purified rat thrombin also showed FGA in vitro, and its FGA was inhibited by the same concentrations of these thrombin inhibitors as those inhibiting the activity in the BAL fluid. On ammonium sulfate fractionation, most of the thrombin activity was recovered in the fraction of 35 to 50% saturation in which most of the FGA was detected. These results suggest that the FGA of the BAL fluid from bleomycin-treated rats was at least partly due to thrombin is responsible, at least in part, for fibroblast growth and pulmonary fibrosis in bleomycin-induced interstitial lung disease.     

Intercellular adhesion molecule-1 and L-selectin regulate bleomycin-induced lung fibrosis

The development of bleomycin-induced lung injury, a model of pulmonary fibrosis, results from inflammatory cell infiltration, a process highly regulated by the expression of multiple adhesion molecules. At present, the identity and role of the adhesion molecules involved in the fibrotic process are unknown. Therefore, bleomycin-induced pulmonary fibrosis was examined in mice lacking L-selectin (L-selectin(-/-)) expression, intercellular adhesion molecule-1 (ICAM-1) expression, or both. After 16 days of intratracheal bleomycin challenge, collagen deposition was inhibited in both L-selectin(-/-) and ICAM-1(-/-) mice when compared with wild-type littermates. Interestingly, collagen deposition was virtually eliminated in L-selectin/ICAM-1(-/-) mice relative to either the L-selectin(-/-) or ICAM-1(-/-) mice. Decreased pulmonary fibrosis was associated with reduced accumulation of leukocytes, including neutrophils and lymphocytes. Decreased mRNA expression of proinflammatory cytokines and transforming growth factor (TGF)-beta1 paralleled the inhibition of collagen deposition. The present study indicates that L-selectin and ICAM-1 play a critical role in pulmonary fibrosis by mediating the accumulation of leukocytes, which regulate the production of proinflammatory cytokines and TGF-beta1. This suggests that these adhesion molecules are potential therapeutic targets for inhibiting human pulmonary fibrosis.     

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.