Effect of Resveratrol on Treatment of Bleomycin-Induced Pulmonary Fibrosis in Rats

Resveratrol has a preventive potential on bleomycin-induced pulmonary fibrosis in prophylactic use; however, it was not studied in the treatment of the fibrosis. This study investigated the role of resveratrol on the treatment of bleomycin-induced pulmonary fibrosis. Intratracheal bleomycin (2.5?mg/kg) was given in fibrosis groups and saline in controls. First dose of resveratrol was given 14?days after bleomycin and continued until sacrifice. On 29th day, fibrosis in lung was estimated by Aschoft's criteria and hydroxyproline content. Bleomycine increased the fibrosis score (3.70?±?1.04) and hydroxyproline levels (4.99?±?0.90?mg/g tissue) as compared to control rats (1.02?±?0.61 and 1.88?±?0.59?mg/g), respectively. These were reduced to 3.16?±?1.58 (P?=?0.0001) and 3.08?±?0.73 (P?>?0.05), respectively, by resveratrol. Tissue malondialdehyde levels in the bleomycin-treated rats were higher (0.55?±?0.22?nmol/mg protein) than that of control rats (0.16?±?0.07; P?=?0.0001) and this was reduced to 0.16?±?0.06 by resveratrol (P?=?0.0001). Tissue total antioxidant capacity is reduced (0.027?±?0.01) by bleomycine administration when compared control rats (0.055?±?0.012?mmol Trolox Equiv/mg protein; P?=?0.0001) and increased to 0.041?±?0.008 (P?=?0.001) by resveratrol. We concluded that resveratrol has some promising potential on the treatment of bleomycin-induced pulmonary fibrosis in rats. However, different doses of the drug should be further studied.     

Beneficial effects of early (but not late) intervention of heme oxygenase-1 on bleomycin-induced pulmonary fibrosis in mice

The aim of this study is to explore the effects of early and late intervention in heme oxygenase-1 (HO-1) expression or activity on pulmonary fibrosis in mice. Mice were divided into four groups: one control and three bleomycin hydrochloride-induced groups in which mice were administered phosphate-buffered saline (PBS), hemin or Cr (III) mesoporphyrin IX chloride (CrMP). Early intervention with hemin, an HO-1 inducer, abrogated bleomycin-induced pulmonary fibrosis (fibrotic/reparative score decrease from 21.0±2.4 to 13.8±1.7, P<0.01), and early intervention with CrMP, an HO-1 inhibitor, worsened bleomycin-induced pulmonary fibrosis (fibrotic/reparative score increase from 21.0±2.4 to 32.5±2.9, P<0.01). Elevated glutathione expression and reduced expression of TGF-β1, hydroxyproline, LDH and MDA were seen in the lungs of the early hemin intervention group compared to that seen in the PBS group (P<0.05). These results taken together show that HO-1 can prevent or ameliorate pulmonary fibrosis and oxidative stress and inflammation at an early stage of pulmonary fibrosis.     

Male sex hormones exacerbate lung function impairment after bleomycin-induced pulmonary fibrosis

The roles of sex hormones as modulators of lung function and disease have received significant attention as differential sex responses to various lung insults have been recently reported. The present study used a bleomycin-induced pulmonary fibrosis model in C57BL/6 mice to examine potential sex differences in physiological and pathological outcomes. Endpoints measured included invasive lung function assessment, immunological response, lung collagen deposition, and a quantitative histological analysis of pulmonary fibrosis. Male mice had significantly higher basal static lung compliance than female mice (P < 0.05) and a more pronounced decline in static compliance after bleomycin administration when expressed as overall change or percentage of baseline change (P < 0.05). In contrast, there were no significant differences between the sexes in immune cell infiltration into the lung or in total lung collagen content after bleomycin. Total lung histopathology scores measured using the Ashcroft method did not differ between the sexes, while a quantitative histopathology scoring system designed to determine where within the lung the fibrosis occurred indicated a tendency toward more fibrosis immediately adjacent to airways in bleomycin-treated male versus female mice. Furthermore, castrated male mice exhibited a female-like response to bleomycin while female mice given exogenous androgen exhibited a male-like response. These data indicate that androgens play an exacerbating role in decreased lung function after bleomycin administration, and traditional measures of fibrosis may miss critical differences in lung function between the sexes. Sex differences should be carefully considered when designing and interpreting experimental models of pulmonary fibrosis in mice.     

Increased expression of epimorphin in bleomycin-induced pulmonary fibrosis in mice

Epimorphin was originally identified as a mesenchymal, cell surface-associated protein that modulates epithelial morphogenesis in embryonic organs, whereas pulmonary fibrosis is a process of wound healing, which in part mimics the process of fetal lung development. We investigated the temporal and spatial changes in the distribution of epimorphin protein and expression of its messenger RNA (mRNA) in bleomycin-induced pulmonary fibrosis in mice. Immunohistochemical analysis showed that low levels of epimorphin were present in the bronchiolar, alveolar, and vascular walls of normal adult lungs. However, from Day 7 until Day 28 after bleomycin treatment, increasing levels of epimorphin immunoreactivity were detected in the mesenchymal cells and in the extracellular matrix within intra-alveolar fibrotic lesions. Moreover, Northern blots showed corresponding increases in epimorphin mRNA expression. Re-epithelialization of epimorphin-rich intra-alveolar fibrosis was complete by Day 28 after bleomycin, and by Day 56, epimorphin immunoreactivity had declined. In situ hybridization and confocal microscopic studies confirmed expression of epimorphin mRNA by mesenchymal cells situated within early fibrotic lesions, whereas immunoelectron microscopy localized the epimorphin to the endoplasmic reticulum of the mesenchymal cells and to the basement membrane and collagen fibrils in the area. These results suggest that epimorphin may contribute to the remodeling of pulmonary fibrosis via epithelial-mesenchymal interactions.     

Susceptibility of Hermansky-Pudlak mice to bleomycin-induced type II cell apoptosis and fibrosis

Pulmonary inflammation, abnormalities in type II cell and macrophage morphology, and pulmonary fibrosis are features of Hermansky-Pudlak Syndrome (HPS), a recessive disorder associated with intracellular trafficking defects. We have previously reported that "Pearl" (HPS2) and "Pale Ear" (HPS1) mouse models have pulmonary inflammatory dysregulation and constitutive alveolar macrophage (AM) activation (Young LR et al., J Immunol 2006;176:4361-4368). In the current study, we used these HPS models to investigate mechanisms of lung fibrosis. Unchallenged HPS1 and HPS2 mice have subtle airspace enlargement and foamy AMs, but little or no histologic evidence of lung fibrosis. Seven days after intratracheal bleomycin (0.025 units), HPS1 and HPS2 mice exhibited increased mortality and diffuse pulmonary fibrosis compared to strain-matched C57BL/6J wild-type (WT) mice. HPS mice had significantly increased collagen deposition, and reduced quasi-static and static compliance consistent with a restrictive defect. The early airway and parenchymal cellular inflammatory responses to bleomycin were similar in HPS2 and WT mice. Greater elevations in levels of TGF-beta and IL-12p40 were produced in the lungs and AMs from bleomycin-challenged HPS mice than in WT mice. TUNEL staining revealed apoptosis of type II cells as early as 5 h after low-dose bleomycin challenge in HPS mice, suggesting that type II cell susceptibility to apoptosis may play a role in the fibrotic response. We conclude that the trafficking abnormalities in HPS promote alveolar apoptosis and pulmonary fibrosis in response to bleomycin challenge.     

Immunomodulation of experimental pulmonary fibrosis by intravenous immunoglobulin (IVIG)

OBJECTIVES: To assess the immunomodulatory effect of intravenous immunoglobulin (IVIG) using an experimental model of bleomycin-induced pulmonary fibrosis. METHODS: Pulmonary fibrosis was induced in C57BL/6 mice by direct intratracheal injection of bleomycin. Mice were treated with IVIG 1 week prior to (prevention protocol), or 10 days following bleomycin injection, when the disease was in progress. The controls used in the study included mice given phosphate buffered saline (PBS) and mice subjected to a commercial individual-IgG. Collagen-I deposits in the affected lungs were detected by Sirius red staining of paraffin embedded lung sections. The collagen-I content was measured by employing the hydroxyproline assay. RESULTS: Prevention of bleomycin-induced pulmonary fibrosis by IVIG has been demonstrated by reduced expression of collagen-I protein in the affected lungs. The hydroxyproline levels in the lungs of the IVIG-treated mice were 214.33 +/- 13.56 microg/1 g tissue, compared to the higher levels in lungs of IgG treated mice (342.44 +/- 35.60 microg/1 g tissue) or untreated controls 328.00 +/- 45.55 microg/1 g tissue, (p < 0.0001). Effective treatment of bleomycin-induced pulmonary fibrosis by IVIG has been demonstrated by the reduced expression of collagen-I protein in the affected lungs, detected by sirius red histological staining. The hydroxyproline levels in the lungs of the IVIG-treated mice were 261.00 +/- 18.81 microg/1 g tissue, in comparison to the higher levels in the lungs of the IgG treated mice (342.43 +/- 32.89 microg/1 g tissue) and of untreated controls (344.33 +/- 49.85 microg/1 g tissue), (p < 0.001). CONCLUSIONS: Based on these preliminary studies, we conclude that IVIG may have a beneficial effect in the down regulation of collagen-I levels in the lungs of mice with bleomycin-induced pulmonary fibrosis.     

盐皮质激素受体在博来霉素诱导的实验性肺纤维化中的作用*

 目的：研究盐皮质激素受体（MR）在博来霉素诱导的实验性肺纤维化进展过程中的作用及机制。方法：将126只6～8周龄雄性C57BL/6小鼠随机分为对照组、博来霉素组和MR阻断剂螺内酯干预组,气管内一次性滴注博来霉素(2.5 mg/kg)溶液建立实验性小鼠肺纤维化模型,螺内酯干预组每天按螺内酯20 mg/kg经灌胃给药。于术后12 h、1 d、2 d、3 d、7 d、14 d和28 d处死小鼠,采用HE染色和Masson染色观察肺组织病理学变化及纤维化程度,采用real-time PCR检测各组肺组织中胶原1(Col1)、Col3、转化生长因子β(TGF-β)、单核细胞趋化蛋白1（MCP-1）及MR mRNA的表达水平。结果：（1）与对照组小鼠相比,博来霉素组及螺内酯干预组小鼠在滴注博来霉素后经历了典型的急性炎症期（12 h～3 d）、纤维化进展期（14 d）和纤维化晚期（28 d）。阻断MR下调早期炎症反应并减轻了纤维化程度。（2）螺内酯干预可以有效降低MR mRNA表达水平;阻断MR在急性炎症期显著下调MCP-1 mRNA的表达,在14 d显著下调TGF-β、Col1和Col3 mRNA表达水平。结论：(1）阻断MR可以明显减轻博来霉素诱导的肺纤维化程度;(2）阻断MR可能通过在急性炎症期调节MCP-1和TGF-β的表达,减轻炎症反应,并在纤维化进展期,下调TGF-β的表达,从而抑制肺纤维化的进展。     

Keratinocyte Growth Factor Decreases Pulmonary Edema, Transforming Growth Factor-Beta and Platelet-Derived Growth Factor-BB Expression, and Alveolar Type II Cell Loss in Bleomycin-Induced Lung Injury

Keratinocyte growth factor (KGF), a potent growth factor for type II pneumocytes and Clara cells, has been shown to prevent the end-stage pulmonary fibrosis and mortality in a rat model of bleomycin-induced lung injury. In this study, protective effects of KGF were explored during the earlier course of bleomycin-induced lung injury by studying protein exudation in alveolar edema fluids, pulmonary expression of transforming growth factor-beta (TGF) and platelet-derived growth factor-BB (PDGF-BB), and changes in type II pneumocytes and Clara cells after i.t. (intratracheal) bleomycin injection following KGF- or saline-pretreatment in rats. Total protein in bronchoalveolar lavage (BAL) fluids after bleomycin injury from KGF-pretreated rats was significantly lower than the levels in saline-pretreated rats. TGF protein in BAL fluids which peaked at day 3 after i.t. bleomycin in saline-pretreated lungs was not significantly increased at any time points in KGF-pretreated rats. PDGF-BB protein in whole lung tissues of KGF-pretreated rats also remained near normal throughout the course after i.t. bleomycin, in contrast to the significant increase in saline-pretreated rats. Numbers of type II pneumocytes and Clara cells in KGF-pretreated lungs after a high dose of bleomycin were close to the normal in intact lungs. At the same dose of bleomycin injury, type II pneumocytes in saline-pretreated lungs were markedly decreased, while the number of Clara cells in these rats was relatively preserved as the pre-injury level. In conclusion, KGF prevents bleomycin-induced end-stage pulmonary injury and mortality probably at least partly by decreasing protein-rich pulmonary edema, protein expression of fibrogenic cytokines TGF and PDGF-BB, and type II cell loss during the course of lung injury.     

Keratinocyte growth factor ameliorates radiation- and bleomycin-induced lung injury and mortality.

Keratinocyte growth factor (KGF) is a growth factor for type II pneumocytes. Type II pneumocyte hyperplasia, a common reaction to lung injury, has been postulated to play an important role in lung repair. The potential protective effect of KGF was therefore studied in rat models of radiation- and bleomycin-induced lung injury. Intratracheal instillation of KGF (5 mg/kg) 72 and 48 hours before 18 Gy of bilateral thoracic irradiation did not significantly improve survival, although histology showed less pneumonitis and fibrosis in KGF-pretreated as compared with control-irradiated rats. Intratracheal pretreatment with KGF in rats receiving intratracheal bleomycin (2.5 U) improved survival at 3 weeks to 100% (20/20 rats) from 40% (8/20 rats) in controls. All KGF-pretreated rats receiving bleomycin were well at 3 weeks and without histological evidence of pulmonary fibrosis whereas the 8 surviving control rats exhibited severe respiratory distress. Finally, in the most lethal challenge to the lung, rats pretreated with intratracheal KGF or saline were challenged with a combination of bleomycin (1.5 U) and bilateral thoracic irradiation (18 Gy). KGF-pretreated rats did not begin to die or show signs of respiratory distress until 7 weeks, whereas all saline-pretreated control rats receiving radiation and bleomycin died within approximately 4 weeks with severe respiratory distress and weight loss. In conclusion, radiation- and bleomycin-induced pulmonary injury and respiratory death are ameliorated by KGF pretreatment, suggesting a protective role for KGF-induced type II pneumocyte proliferation in lung injury.     

Protease-activated receptor-2 induces myofibroblast differentiation and tissue factor up-regulation during bleomycin-induced lung injury: potential role in pulmonary fibrosis

Idiopathic pulmonary fibrosis constitutes the most devastating form of fibrotic lung disorders and remains refractory to current therapies. The coagulation cascade is frequently activated during pulmonary fibrosis, but this observation has so far resisted a mechanistic explanation. Recent data suggest that protease-activated receptor (PAR)-2, a receptor activated by (among others) coagulation factor (F)Xa, plays a key role in fibrotic disease; consequently, we assessed the role of PAR-2 in the development of pulmonary fibrosis in this study. We show that PAR-2 is up-regulated in the lungs of patients with idiopathic pulmonary fibrosis and that bronchoalveolar lavage fluid from these patients displays increased procoagulant activity that triggers fibroblast survival. Using a bleomycin model of pulmonary fibrosis, we show that bleomycin induces PAR-2 expression, as well as both myofibroblast differentiation and collagen synthesis. In PAR-2-/- mice, both the extent and severity of fibrotic lesions are reduced, whereas myofibroblast differentiation is diminished and collagen expression is decreased. Moreover, fibrin deposition in the lungs of fibrotic PAR-2-/- mice is reduced compared with wild-type mice due to differential tissue factor expression in response to bleomycin. Taken together, these results suggest an important role for PAR-2 in the development of pulmonary fibrosis, and the inhibition of the PAR-2-coagulation axis may provide a novel therapeutic approach to treat this devastating disease.     

Inhibition of bleomycin-induced pulmonary fibrosis in mice by the matrix metalloproteinase inhibitor batimastat

Bleomycin-induced pulmonary fibrosis is known to be associated with the increased activity of two gelatinases, matrix metalloproteinase (MMP)-2 and MMP-9, in bronchoalveolar lavage (BAL). This study has investigated the effect of a synthetic inhibitor of MMP, batimastat, on the development of pulmonary fibrosis induced by bleomycin administration in mice. Animals were intranasally instilled with saline or bleomycin (0.5 mg in 100 microl per mouse). Batimastat (30 mg/kg) or vehicle alone was administered by intraperitoneal injection 24 h and 1 h before saline or bleomycin instillation, and then daily at the same dosage until the end of the study. Fifteen days after bleomycin administration, BAL was performed and the lung was removed. Treatment of mice with batimastat significantly reduced bleomycin-induced lung fibrosis, as shown in the lung by histopathological examination and by a decrease in hydroxyproline levels. Batimastat also prevented the increase in BAL macrophage and lymphocyte numbers, whereas it did not show any effect on the increased expression of active transforming growth factor-beta (TGF-beta) in BAL. Batimastat treatment was effective in reducing MMP-2 and MMP-9 activity as well as the tissue inhibitor of metalloproteinase-1 (TIMP-1) level in BAL. These results suggest that administration of the MMP inhibitor batimastat is useful in preventing experimental pulmonary fibrosis induced by bleomycin and raises the possibility of a therapeutic approach to human pulmonary fibrotic disease.     

IL-12p40(-/-) mice treated with intratracheal bleomycin exhibit decreased pulmonary inflammation and increased fibrosis.

Pulmonary lymphohistiocytic inflammation and fibrosis characterize bleomycin (BLM) lung injury. IL-12, a p70 cytokine produced primarily by macrophages and dendritic cells, promotes T-helper-1-mediated inflammation. IL-12 production by blood monocytes and bronchoalveolar large mononuclear cells (BAMC) was investigated at Days 1-14 following intratracheal administration of BLM. In the lung, BAMC showed a large peak of IL-12 expression at Day 5 that returned rapidly toward baseline. IL-12p40(-/-) mice treated with BLM intratracheally showed less pulmonary mononuclear cell inflammation at Day 7 than wild-type controls, whereas pulmonary fibrosis and hydroxyproline content were increased in IL-12p40(-/-) mice at Day 14. The expression of IP-10, RANTES, and eotaxin were decreased in IL-12p40(-/-) mice and lung IL-6 expression was increased, all compared to controls. We conclude that IL-12 promotes the lymphohistiocytic response to BLM and may inhibit the late development of pulmonary fibrosis.     

Immunomodulation of experimental pulmonary fibrosis by intravenous immunoglobulin (IVIG)

Objectives: To assess the immunomodulatory effect of intravenous immunoglobulin (IVIG) using an experimental model of bleomycin-induced pulmonary fibrosis.

Methods: Pulmonary fibrosis was induced in C57BL/6 mice by direct intratracheal injection of bleomycin. Mice were treated with IVIG 1 week prior to (prevention protocol), or 10 days following bleomycin injection, when the disease was in progress. The controls used in the study included mice given phosphate buffered saline (PBS) and mice subjected to a commercial individual-IgG. Collagen-I deposits in the affected lungs were detected by Sirius red staining of paraffin embedded lung sections. The collagen-I content was measured by employing the hydroxyproline assay.

Results: Prevention of bleomycin-induced pulmonary fibrosis by IVIG has been demonstrated by reduced expression of collagen-I protein in the affected lungs. The hydroxyproline levels in the lungs of the IVIG-treated mice were 214.33 ± 13.56 μg/1 g tissue, compared to the higher levels in lungs of IgG treated mice (342.44 ± 35.60 μg/1 g tissue) or untreated controls 328.00 ± 45.55 μg/1 g tissue, (p < 0.0001). Effective treatment of bleomycin-induced pulmonary fibrosis by IVIG has been demonstrated by the reduced expression of collagen-I protein in the affected lungs, detected by sirius red histological staining. The hydroxyproline levels in the lungs of the IVIG-treated mice were 261.00 ± 18.81 μg/1 g tissue, in comparison to the higher levels in the lungs of the IgG treated mice (342.43 ± 32.89 μg/1 g tissue) and of untreated controls (344.33 ± 49.85 μg/1 g tissue), (p < 0.001).

Conclusions: Based on these preliminary studies, we conclude that IVIG may have a beneficial effect in the down regulation of collagen-I levels in the lungs of mice with bleomycin-induced pulmonary fibrosis.     

Inhibition of pulmonary fibrosis by the chemokine IP-10/CXCL10

Pulmonary fibrosis is an enigmatic and devastating disease with few treatment options, now thought to result from abnormal wound healing in the lung in response to injury. We have previously noted a role for the chemokine interferon gamma-inducible protein of 10 kD (IP-10)/CXC chemokine ligand 10 in the regulation of cutaneous wound healing, and consequently investigated whether IP-10 regulates pulmonary fibrosis. We found that IP-10 is highly expressed in a mouse model of pulmonary fibrosis induced by bleomycin. IP-10-deficient mice exhibited increased pulmonary fibrosis after administration of bleomycin, suggesting that IP-10 limits the development of fibrosis in this model. Substantial fibroblast chemoattractant and proliferative activities were generated in the lung after bleomycin exposure. IP-10 significantly inhibited fibroblast responses to the chemotactic, but not the proliferative activity generated, suggesting that IP-10 may attenuate fibroblast accumulation in bleomycin-induced pulmonary fibrosis by limiting fibroblast migration. Consistent with this inhibitory activity of IP-10 on fibroblast migration, fibroblast accumulation in the lung after bleomycin exposure was dramatically increased in IP-10-deficient mice compared with wild-type mice. Conversely, transgenic mice overexpressing IP-10 were protected from mortality after bleomycin exposure, and demonstrated decreased fibroblast accumulation in the lung after challenge compared with wild-type mice. Our findings suggest that interruption of fibroblast recruitment may represent a novel therapeutic strategy for pulmonary fibrosis, which could have applicability to a wide range of fibrotic illnesses.     

Gender-based differences in bleomycin-induced pulmonary fibrosis

The role of gender and sex hormones is unclear in host response to lung injury, inflammation, and fibrosis. To examine gender influence on pulmonary fibrosis, male and female rats were given endotracheal injections of either saline or bleomycin. Female rats showed higher mortality rates and more severe fibrosis than did male rats, as indicated by higher levels of lung collagen deposition and fibrogenic cytokine expression. To clarify the potential role of female sex hormones in lung fibrosis, female rats were ovariectomized and treated with either estradiol or vehicle plus endotracheal injections of either saline or bleomycin. The results showed diminished fibrosis in the ovariectomized, bleomycin-treated rats without hormone replacement. Estradiol replacement restored the fibrotic response to that of the intact female mice in terms of lung collagen deposition and cytokine expression, which was accompanied by higher plasma estradiol levels. Furthermore, fibroblasts from bleomycin-treated rats exhibited increased responsiveness to estradiol treatment, causing dose-dependent increases in procollagen 1 and transforming growth factor-beta1 mRNA expression relative to untreated controls. Taken together these findings suggest that female mice may have an exaggerated response to lung injury relative to male mice because of female sex hormones, which have direct fibrogenic activity on lung fibroblasts. This may provide a mechanism for a hormonally mediated intensification of pulmonary fibrosis.     

Attenuation of lung inflammation and fibrosis in interferon-gamma-deficient mice after intratracheal bleomycin

Because mouse strains susceptible to bleomycin, such as C57BL/ 6J, tend to produce T helper type 1 (Th1) cytokines in response to immune activation, we hypothesized that the inflammatory response to bleomycin is mediated, in part, by local production of the Th1 cytokine interferon-gamma (IFN-gamma). Consistent with this hypothesis, fibrosis-prone C57BL/6J and A/J mice demonstrated significantly elevated expression of IFN-gamma protein (by enzyme-linked immunosorbent assay) in bronchoalveolar lavage fluid at 24 h, and subsequently increased lung inflammation, weight loss, and mortality 10 d after intratracheal bleomycin administration compared with fibrosis-resistant BALB/c mice or saline control mice. To directly determine a role for IFN-gamma in bleomycin toxicity, we exposed C57BL/6J mice with a homozygous null mutation of the IFN-gamma gene (IFN-gamma[-/-]) and wild-type C57BL/6J mice to intratracheal bleomycin. IFN-gamma(-/-) mice demonstrated significantly lower parenchymal inflammation, weight loss, and mortality 10 d after 5 U/kg intratracheal bleomycin administration compared with control mice. At 3 wk after 1.5 U/kg bleomycin exposure, single lung collagen determined by hydroxyproline assay was significantly lower in IFN-gamma(-/-) mice compared with wild-type C57BL/6J mice. Together, these results suggest that IFN-gamma mediates, in part, bleomycin-induced pulmonary inflammation and fibrosis.     

Double intratracheal instillation of keratinocyte growth factor prevents bleomycin-induced lung fibrosis in rats

Alveolar re-epithelialization is necessary in the repair of damaged alveolar epithelium after lung injury. Keratinocyte growth factor (KGF) has been shown to be a potent proliferation and differentiation factor for rat alveolar type II cells. The present study examined whether KGF would prevent bleomycin-induced lung fibrosis. Adult rats were anaesthetized and recombinant human KGF (rhKGF) (150 μg/kg) or saline was injected intratracheally at 48 h before and 24 h after bleomycin (Bleo, 5 mg/kg) instillation. Seven and 14 days after the last administration, rat lungs were processed for lung physiology, immunohistochemistry, and in situhybridization. Double instillation of KGF prevented the loss of body weight and reduction in total lung capacity (TLC) due to Bleo, and markedly attenuated the protein accumulation and mRNA expression of collagen types I and III and the decreased expression of surfactant protein mRNAs in the fibrotic lesions of Bleo-treated rats. KGF may play an important role in maintaining alveolar epithelium and repairing the damaged epithelium after lung injury. © 1998 John Wiley & Sons, Ltd.     

博莱霉素肺纤维化小鼠血管内皮细胞的研究

目的:研究C57BL/6小鼠肺微小血管内皮细胞血栓调节蛋白(TM)与因子Ⅷ相关抗原(vWf)的分布及博莱霉素(BLM)致肺纤维化过程中,血管内皮细胞亚型的转变。方法:采用双重免疫荧光染色及荧光强度定量分析法。结果:①正常C57BL/6小鼠肺泡毛细血管内皮细胞表面显示多数连续性线样TM荧光而vWf较少阳性,肺微小血管内皮细胞呈现vWf阳性。②BLM组小鼠内皮细胞TM荧光明显弱于正常,而vWf荧光显著强于正常水平。结论:①正常C57BL/6小鼠肺泡毛细血管内皮细胞以TM表达为主型,而非vWf表达为主型。②BLM致肺纤维化过程中,肺血管内皮细胞由以TM表达为主型转变为以vWf表达为主型,两抗原可被认为是内皮细胞损伤的标志物。     

Transforming growth factor-alpha deficiency reduces pulmonary fibrosis in transgenic mice

Despite evidence that implicates transforming growth factor-alpha (TGF-alpha) in the pathogenesis of acute lung injury, the contribution of TGF-alpha to the fibroproliferative response is unknown. To determine whether the development of pulmonary fibrosis depends on TGF-alpha, we induced lung injury with bleomycin in TGF-alpha null-mutation transgenic mice and wild-type mice. Lung hydroxyproline content was 1.3, 1.2, and 1.6 times greater in wild-genotype mice than in TGF-alpha-deficient animals at Days 10, 21, and 28, respectively, after a single intratracheal injection of bleomycin. At Days 7 and 10 after bleomycin treatment, lung total RNA content was 1.5 times greater in wild-genotype mice than in TGF-alpha-deficient animals. There was no significant difference between mice of the two genotypes in lung total DNA content or nuclear labeling indices after bleomycin administration. Wild-genotype mice had significantly higher lung fibrosis scores at Days 7 and 14 after bleomycin treatment than did TGF-alpha-deficient animals. There was no significant difference between TGF-alpha-deficient mice and wild-genotype mice in lung inflammation scores after bleomycin administration. To determine whether expression of other members of the epidermal growth factor (EGF) family is increased after bleomycin-induced injury, we measured lung EGF and heparin-binding- epidermal growth factor (HB-EGF) mRNA levels. Steady-state HB-EGF mRNA levels were 321% and 478% of control values in bleomycin-treated lungs at Days 7 and 10, respectively, but were not significantly different in TGF-alpha-deficient and in wild-genotype mice. EGF mRNA was not detected in normal or bleomycin-treated lungs of mice of either genotype. These results show that TGF-alpha contributes significantly to the pathogenesis of pulmonary fibrosis after bleomycin-induced injury, and that compensatory increases in other EGF family members do not occur in TGF-alpha-deficient mice.     

Localization of HSP47 mRNA in murine bleomycin-induced pulmonary fibrosis

Heat shock protein 47 (HSP47) is a collagen-specific molecular chaperone that has been shown to play a major role in the processing and/or secretion of procollagen. However, the knowledge on which cells are actually synthesizing HSP47 in the lung parenchyma in pulmonary fibrosis was only limited. The aim of the present study was to investigate the localization of HSP47 messenger ribonucleic acid (mRNA) in normal lung and in the lungs of mice in bleomycin-induced pulmonary fibrosis, using in situ hybridization. For the purpose, ICR mice were intravenously injected with 10 mg/kg per day of bleomycin for five consecutive days. The lung cells expressing HSP47 mRNA were identified in control (saline alone) and bleomycin-treated mice by in situ hybridization. The signal for HSP47 mRNA was markedly increased in bleomycin-treated lungs compared with that of controls. HSP47 mRNA was localized in α-smooth-muscle-actin-positive myofibroblasts, surfactant-protein-A-positive type II pneumocytes, and F4/80-positive macrophages in the active fibrotic areas. These results suggest that these cells may synthesize procollagen in the fibrotic process of bleomycin-treated lungs through upregulation of HSP47 mRNA and play an important role in fibrogenesis.