Development Of Bleomycin-induced Pulmonary Fibrosis Research Articles

Therapeutic Efficacy of Cintredekin Besudotox (IL13-PE38QQR) in Murine Lung Fibrosis Is Unaffected by Immunity to Pseudomonas aeruginosa Exotoxin A

BackgroundWe have previously explored a therapeutic strategy for specifically targeting the profibrotic activity of IL-13 during experimental pulmonary fibrosis using a fusion protein comprised of human IL-13 and a mutated form of Pseudomonas aeruginosa exotoxin A (IL13-PE) and observed that the intranasal delivery of IL13-PE reduced bleomycin-induced pulmonary fibrosis through its elimination of IL-13-responsive cells in the lung. The aim of the present study was to determine whether the presence of an immune response to P. aeruginosa and/or its exotoxin A (PE) would diminish the anti-fibrotic properties of IL13-PE.Methodology/Principal FindingsFourteen days after P. aeruginosa infection, C57BL/6 mice were injected with bleomycin via the intratracheal route. Other groups of mice received 4 doses of saline or IL13-PE by either intranasal or intraperitoneal application, and were challenged i.t. with bleomycin 28 days later. At day 21 after bleomycin, all mice received either saline vehicle or IL13-PE by the intranasal route and histopatological analyses of whole lung samples were performed at day 28 after bleomycin. Intrapulmonary P. aeruginosa infection promoted a neutralizing IgG2A and IgA antibody response in BALF and serum. Surprisingly, histological analysis showed that a prior P. aeruginosa infection attenuated the development of bleomycin-induced pulmonary fibrosis, which was modestly further attenuated by the intranasal administration of IL13-PE. Although prior intranasal administration of IL13-PE failed to elicit an antibody response, the systemic administration of IL13-PE induced a strong neutralizing antibody response. However, the prior systemic sensitization of mice with IL13-PE did not inhibit the anti-fibrotic effect of IL13-PE in fibrotic mice.ConclusionsThus, IL13-PE therapy in pulmonary fibrosis works regardless of the presence of a humoral immune response to Pseudomonas exotoxin A. Interestingly, a prior infection with P. aeruginosa markedly attenuated the pulmonary fibrotic response suggesting that the immune elicitation by this pathogen exerts anti-fibrotic effects.

Anti-type IV collagenase single-chain antibody ameliorates bleomycin-induced experimental pulmonary fibrosis in mice

To study the effect of anti-type IV collagenase single-chain antibody scFv (3G11) on bleomycin (BLM)-induced pulmonary fibrosis. C57BL/6 mice were divided into six groups (blank, saline control, BLM, low-dose treatment, intermediate-dose treatment, and high-dose treatment), the animal model of pulmonary fibrosis was induced with 400 ng/g intratracheal BLM. The day that treatment groups were injected with BLM was marked Day 0. Then at Days 1 - 7, scFv (3G11) was injected once intraperitoneally each day with three dosage [low-dose treatment (15 microg/g), intermediate-dose treatment (30 microg/g) and high-dose treatment (45 microg/g)]. At Day 21, 6 mice of each group (saline control, BLM, intermediate-dose treatment) were sacrificed and pathomorphological changes of left lungs evaluated with HE stained sections. Meanwhile, 6 mice of each group (blank, saline control, BLM, low-dose treatment, intermediate-dose treatment, and high-dose treatment) were sacrificed, the content of hydroxyproline was detected to measure the degree of collagen deposition. Macrophages were extracted from murine abdominal cavity and primarily cultured. And the inhibition of matrix metalloproteinase (MMP)-2 and MMP-9 excretion by different concentrations of scFv (3G11) (0, 15, 30, 45, and 60 micromol/L) was determined by gelatin zymography. By image analysis, the degree of fibrosis in the lungs of treated group was lighter than that of the BLM group. The percentages of the area of interalveolar septum (45.3% +/- 3.2%) and the number of nucleated cells (451 +/- 47) of treated group were remarkably reduced as compared with the BLM group (59.0% +/- 3.0%, 599 +/- 42, both P < 0.01). The content of hydroxyproline of the intermediate-dose treatment group [(0.82 +/- 0.05) microg/mg] and high-dose treatment group [(0.80 +/- 0.03) microg/mg] was lower than that of the BLM group [(0.92 +/- 0.07) microg/mg, P < 0.05, P < 0.01]. The result of gelatin zymography demonstrated that the excretion of MMP-2 and MMP-9 by macrophage was inhibited by scFv (3G11) at the concentration of 15 micromol/L. Single-chain antibody directed against type IV collagenase might inhibit the development of bleomycin-induced pulmonary fibrosis.

Effects of a leukotriene B4 receptor antagonist on bleomycin-induced pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a devastating disease with poor prognosis. Leukotrienes play an important role in IPF, and leukotriene (LT)B(4) is one of the key eicosanoids in IPF. In this study, we investigated whether ONO-4057, a LTB(4) receptor (BLTR) antagonist is capable of preventing bleomycin-induced pulmonary fibrosis. On day 1, C57BL/6 male mice were given a single intratracheal injection of bleomycin (2.5 mg x kg(-1)), and ONO-4057 (1.0 mg x kg(-1)) or vehicle alone, administered by intraperitoneal injection on days 1-5 each week for 3 weeks after the bleomycin injection. ONO-4057 reduced the total cell count in bronchoalveolar lavage fluid (BALF) on days 7, 14 and 21 and the Ashcroft score and the lung hydroxyproline content on days 14 and 21. The LTB(4), interleukin (IL)-6, IL-13, transforming growth factor (TGF)-beta levels in BALF and the TGF-beta expression in lung tissue, assessed by immunohistochemistry were decreased on day 7, whereas interferon (IFN)-gamma level in BALF was increased on day 14. The results of this study indicated that the BLTR antagonist inhibited the development of bleomycin-induced pulmonary fibrosis in mice by decreasing inflammation and altering TGF-beta, IL-6, IL-13 and IFN-gamma.

Effects of Th2 pulmonary inflammation in mice with bleomycin‐induced pulmonary fibrosis

Leucocytes, especially lymphocytes and neutrophils, as well as alveolar macrophages, that infiltrate into the lung are involved in the development of pulmonary fibrosis. However, the role of T helper (Th)2-type inflammation, mediated by Th2 cells and eosinophils, in fibrosis remains unknown. Transgenic mice deficient in the transcriptional repressor, Bcl6, display an attenuation of Th2 cytokine production. We studied the effects of Th2-type pulmonary inflammation on bleomycin-induced pulmonary fibrosis using Bcl6 transgenic mice. Bleomycin was administered to ovalbumin (OVA)-sensitized Bcl6 transgenic and wild-type mice by intratracheal instillation during sequential OVA antigen challenge. Concentrations of transforming growth factor-beta1 in the BAL fluid were measured 2 weeks after bleomycin administration. At the same time lung tissue was examined histopathologically, and homogenized to assess collagen levels and Th1/Th2 cytokine mRNA expression. Although OVA-sensitized, bleomycin-treated Bcl6 transgenic mice had markedly lower numbers of eosinophils in both BAL and lung tissue compared with OVA-sensitized, bleomycin-treated wild-type mice, the development of pulmonary fibrosis in response to bleomycin was similar in Bcl6 transgenic mice and wild-type mice. These results suggest that Th2-dominant inflammation in the lung is not essential for the development of bleomycin-induced pulmonary fibrosis.

Antifibrotic action of pirfenidone and prednisolone: Different effects on pulmonary cytokines and growth factors in bleomycin-induced murine pulmonary fibrosis

Pirfenidone, a broad-spectrum antifibrotic agent, is known to have efficacy in certain fibrotic disease models, and is under clinical trials in patients with idiopathic pulmonary fibrosis. We investigated the antifibrotic effect of pirfenidone, and its regulatory effect on various pulmonary cytokines, in bleomycin-induced lung fibrosis in mice at the protein level, using prednisolone as a reference agent. Pirfenidone attenuated the bleomycin-induced pulmonary fibrosis at a minimum effective dose of 30 mg/kg/day t.i.d. from the analysis of lung hydroxyproline content. Both pirfenidone (30, 100 mg/kg/day t.i.d) and prednisolone (3, 15 mg/kg/day q.d.) suppressed lung inflammatory edema; however, prednisolone failed to suppress pulmonary fibrosis, which was significantly suppressed only by pirfenidone. Both pirfenidone and prednisolone suppressed the increase in lung interleukin (IL)-1β, IL-6, IL-12p40 and monocyte chemoattractant protein (MCP)-1 levels induced by bleomycin. On the other hand, pirfenidone prevented the bleomycin-induced decrease in lung interferon (IFN)-γ levels, while prednisolone had no such effect. Furthermore, pirfenidone suppressed elevation of lung basic-fibroblast growth factor (bFGF) and transforming growth factor (TGF)-β1 levels, but prednisolone had no such effect. The increases in lung stroma cell derived factor (SDF)-1α and IL-18 were also suppressed. These findings suggest that pirfenidone exerts its antifibrotic effect through regulation of lung IFN-γ, bFGF and TGF-β1 levels during the development of bleomycin-induced pulmonary fibrosis in mice. The effect on SDF-1α and IL-18 levels may also be related to the antifibrotic effects of pirfenidone.

The role of collagenases in experimental pulmonary fibrosis

Matrix metalloproteinases (MMPs) expression plays a critical role in extracellular matrix deposition. Although several pieces of evidence have so far indicated that gelatinase contributes to the development of pulmonary fibrosis, the role of collagenase remains uncertain. In this study, we attempted to determine the role of collagenase using a bleomycin-induced pulmonary fibrosis model. Bleomycin was instilled into mice intratracheally. Bronchoalveolar lavage fluid (BAL) specimens were analyzed for gelatin and casein zymography, as well as by immunoblotting. The histology of the lungs and hydroxyproline contents were also assessed. MMPs inhibitor, CGS27023A, was simultaneously orally administered. Collagenases were induced in BAL fluids after bleomycin administration based on the data of zymography and immunohistochemistry. The co-administration of MMPs inhibitor, CGS27023A, with bleomycin resulted in worsening pulmonary fibrosis with inhibition of collagenase. The worsening of pulmonary fibrosis was mainly induced by CGS27023A administration in the late phase of bleomycin-induced pulmonary fibrosis development, but not in the early phase. The present data indicated that collagenase plays an anti-fibrotic role in the bleomycin-induced pulmonary fibrosis model. Collagenase has a greater effect on fibrosis phase than inflammatory phase in the bleomycin-induced pulmonary fibrosis in the mice.

A complex, tissue-specific role for plasmin and its regulators in modulating fibrogenic activity

it has long been known that tissue injury often leads to the infiltration of interstitial spaces with plasma, resulting in the polymerization of fibrin as a provisional matrix to support the migration of cells that mediate healing process. When all goes well, during the course of tissue repair the

Cysteinyl-leukotriene 1 receptor antagonist attenuates bleomycin-induced pulmonary fibrosis in mice

Leukotrienes are lipid mediators of inflammation derived from the 5-lipoxygenase pathway of arachidonic acid metabolism, and recent evidence suggests that they play an important role in pulmonary fibrosis. Montelukast is a cysteinyl-leukotriene 1 receptor antagonist that has been found to reduce airway remodeling, including subepithelial fibrosis, in a murine model of asthma, but the therapeutic effect of montelukast on pulmonary fibrosis remains unclear. In this study, we investigated whether montelukast is capable of preventing bleomycin-induced pulmonary fibrosis in mice. On day 1, C57BL/6 mice were given a single intratracheal injection of bleomycin (2.5 mg/kg), and montelukast (1.0 mg/kg) or vehicle alone subcutaneously 2 h later and on days 1–5 of each week for two weeks. The total number of cells in bronchoalveolar lavage fluid (BALF) was reduced in the montelukast group on day 7 and on day 14, and cellular inflammation and fibrosis were attenuated on day 14 as indicated by significant decrease in the Ashcroft score and lung hydroxyproline content. Although cysteinyl-leukotriene level in BALF was not significantly different, transforming growth factor β (TGFβ) level in BALF by ELISA and TGFβ expression in lung tissue by immunohistochemistry was reduced on day 14 in the montelukast group. The results of this study show that montelukast inhibits the inflammatory process and development of bleomycin-induced pulmonary fibrosis in mice and that these effects may be associated with a decrease in TGFβ expression. They also suggest that montelukast may serve as a new therapy for patients with interstitial pulmonary fibrosis.

Effects of fish oil treatment on bleomycin-induced pulmonary fibrosis in mice

Bleomycin is an antibiotic used to treat a variety of neoplasms. A major side-effect of bleomycin therapy is the induction of an intense inflammatory response that develops into pulmonary fibrosis. Several studies have shown that certain polyunsaturated fatty acids found in fish oil reduce the inflammatory response in vivo. Fish oil has been employed for the treatment of several pathologies such as glomerulonephritis, cardiovascular diseases, rheumatoid arthritis, and even as an adjuvant in cancer therapy. This study examined the effects of fish oil treatment on the development of bleomycin-induced pulmonary fibrosis. Mice were intraperitoneally treated with bleomycin or with saline daily for 10 days, and 15 days after the last injection they started to receive fish oil by gavage for 14 days. The lungs were processed for light microscopy, biochemical and immunohistochemical investigations. Fish oil did not prevent the development of pulmonary fibrosis after the injury as shown by light microscopy, cytokines immunohistochemical analysis, TBARS content and protein levels in the lung. In addition however, fish oil itself induced a slight inflammatory process in the lung, as observed by the increase in cellularity, vasodilatation in the lung parenchyma, TBARS content, and a slight increase in the lung protein content.

Prostacyclin agonist with thromboxane synthase inhibitory activity (ONO-1301) attenuates bleomycin-induced pulmonary fibrosis in mice

The balance between prostacyclin and thromboxane A2 (TXA2) plays an important role in pulmonary homeostasis. However, little information is available regarding the therapeutic potency of these prostanoids for pulmonary fibrosis. We have recently developed ONO-1301, a novel long-acting prostacyclin agonist with thromboxane synthase inhibitory activity. Thus we investigated whether repeated administration of ONO-1301 attenuates bleomycin-induced pulmonary fibrosis in mice. After intratracheal injection of bleomycin or saline, mice were randomized to receive repeated subcutaneous administration of ONO-1301 or vehicle. Bronchoalveolar lavage (BAL) and histological analyses were performed at 3, 7, and 14 days after bleomycin injection. In vitro studies using mouse lung fibroblasts were also performed. ONO-1301 significantly attenuated the development of bleomycin-induced pulmonary fibrosis, as indicated by significant decreases in Ashcroft score and lung hydroxyproline content. ONO-1301 significantly reduced total cell count, neutrophil count, and total protein level in BAL fluid in association with a marked reduction of TXB2. A single administration of ONO-1301 significantly increased plasma cAMP level for >2 h. In vitro, ONO-1301 and a cAMP analog dose-dependently reduced cell proliferation in mouse lung fibroblasts. The reduction in cell proliferation by ONO-1301 was attenuated by a protein kinase A (PKA) inhibitor. Furthermore, bleomycin mice treated with ONO-1301 had a significantly higher survival rate than those given vehicle. These results suggest that repeated administration of ONO-1301 attenuates the development of bleomycin-induced pulmonary fibrosis and improves survival in bleomycin mice, at least in part by inhibition of TXA2 synthesis and activation of the cAMP/PKA pathway.

Opposing Regulatory Roles of Complement Factor 5 in the Development of Bleomycin-Induced Pulmonary Fibrosis

The mechanisms of idiopathic pulmonary fibrosis pathogenesis, a chronic and progressive interstitial lung disease, remain elusive. The complement system, a crucial arm of the innate immune response, plays a pivotal role in several pathological disorders; however, the contribution of individual complement components to lung fibrosis has not yet been examined. Complement factor 5 (C5) and its cleavage product C5a are critical mediators in inflammatory diseases. Thus, to evaluate the role of C5 in lung fibrosis, we compared congenic C5-sufficient and C5-deficient mice in a well-characterized murine model of bleomycin-induced pulmonary fibrosis. C5-deficient mice had an exaggerated inflammatory phenotype compared with C5-sufficient mice during acute bleomycin-induced lung injury. These findings suggest a protective and anti-inflammatory role for C5, which was linked to the regulation of matrix metalloproteinases involved in cell migration. In contrast, C5 had a detrimental effect during chronic stages of bleomycin-induced injury, indicating a profibrotic role for C5. This deleterious activity for C5 was associated with expression of the fibrogenic cytokine TGF-beta1 and matrix metalloproteinase-3, an important mediator in fibroblast contraction. Altogether, our data reveal novel and opposing roles for C5 in both inflammation and tissue repair. Furthermore, these findings provide insight into the development of new therapeutic strategies for idiopathic pulmonary fibrosis patients.

Angiotensin II antagonism fails to ameliorate bleomycin-induced pulmonary fibrosis in mice

Based on current evidence, transforming growth factor (TGF)-beta plays a central pathogenic role in the development of pulmonary fibrosis. There is growing evidence that angiotensin II can serve as a stimulus for TGF-beta-mediated lung fibrosis. However, the role of angiotensin II in the pathobiology of pulmonary fibrosis in vivo remains unclear and the therapeutic potential for targeting angiotensin II in a bleomycin-induced pulmonary fibrosis model is not well known. Therefore, the aim of this study was to test whether the angiotensin II antagonist, losartan, attenuated the development of bleomycin-induced pulmonary fibrosis in two distinct murine strains, C57/BL6 and Sv129. This was determined by histopathology and quantification of collagen content by hydroxyproline assay. Despite demonstrable angiotensin II antagonism in vivo and a reduction in measures of acute lung injury, losartan therapy, at a dose shown to reduce renal and cardiac fibrosis in mice, failed to significantly ameliorate bleomycin-induced pulmonary fibrosis. In conclusion, these data suggest that the pulmonary fibrotic disease process in vivo is not solely dependent on angiotensin II activity and the potential for angiotensin II receptor blockers as a therapeutic strategy in patients with pulmonary fibrosis may be limited.

Treatment with alpha-galactosylceramide attenuates the development of bleomycin-induced pulmonary fibrosis.

Pulmonary fibrosis is an end-stage disorder for which efficacious therapeutic options are not readily available. Although its pathogenesis is poorly understood, pulmonary fibrosis occurs as a result of various inflammations. NKT cells modulate inflammation because of their ability to produce large amounts of cytokines by stimulation with their glycolipid ligand. In the present study, we investigated the effects of alpha-galactosylceramide (alpha-GalCer), a selective NKT cell ligand, on the development of bleomycin-induced pulmonary fibrosis. Treatment of mice with alpha-GalCer prolonged their survival under bleomycin administration by attenuating the development of pulmonary fibrosis. The protective effects of alpha-GalCer were associated with an increase in the pulmonary level of IFN-gamma and a decrease in the pulmonary level of fibrogenic cytokines such as TGF-beta and connective tissue growth factor. The initial pulmonary inflammation caused by bleomycin was also attenuated by alpha-GalCer with the reduction of the macrophage inflammatory protein-2 level. The protective effects of alpha-GalCer were markedly reduced in mice lacking NKT cells or as a result of treatment with anti-IFN-gamma Ab. These results suggest that alpha-GalCer suppresses bleomycin-induced acute pulmonary inflammation and thus attenuates the development of pulmonary fibrosis possibly by regulating several cytokine levels.

Interleukin-12 Attenuates Pulmonary Fibrosis via Induction of Interferon-γ

Few studies have addressed the importance of vascular remodeling in the lung during the development of bleomycin-induced pulmonary fibrosis (BPF). Lung-derived angiogenic activity is increased in bleomycin-treated mice as compared to saline solution-treated control mice. Moreover, we have shown that the CXC chemokines, macrophage in inflammatory protein-2 and macrophage in inflammatory protein-2 and interferon (IFN)-inducible protein 10 (IP-10), have an important role in the pathogenesis of BPF that is mediated via the regulation of angiogenesis. Interleukin (IL)-12 is a potent inducer of IFN-γ and hence the angiostatic CXC chemokines, IP-10 and monokine induced by IFN-γ (MIG). We postulated that interleukin (IL)-12 would attenuate BPF via inhibition of angiogenesis. To test this hypothesis, we administered IL-12 or human serum albumin to bleomycin-treated CBA/J mice, by daily intraperitoneal injection until day 12. Mice treated with IL-12 demonstrated decreased hydroxyproline levels as compared to human serum albumin-treated control mice (24.2 ± 1.4 vs 30.8 ± 2.5; p < 0.05). Furthermore, administration of IL-12 led to a time-dependent increase in lung IFN-γ, IP-10, and MIG. The antifibrotic effect of IL-12 could be attenuated with simultaneous administration of neutralizing anti-IFN-γ antibodies. These findings support the notion that the antifibrotic effects of IL-12 are mediated through IFN-γ and subsequently IP-10 and MIG.

A Total Fibrinogen Deficiency Is Compatible with the Development of Pulmonary Fibrosis in Mice

In addition to their well-known roles in hemostasis, fibrinogen (Fg) and fibrin (Fn) have been implicated in a number of other physiological and pathophysiological events. One of these involves the fibroproliferative response after acute lung injury, which is the focus of the current study. Mice with a total Fg deficiency (FG(-/-)) were generated by breeding heterozygous (FG(+/-)) pairs, each of which contained an allele with a targeted deletion of its Fg-gamma-chain gene. The resulting FG(-/-) animals did not possess detectable plasma Fg. FG(-/-) mice were then used to assess the roles of Fg and Fn in a bleomycin-induced acute lung injury model. Intratracheal administration of bleomycin in wild-type and FG(-/-) mice resulted in equivalent deposition of interstitial collagen and fibrotic lesions at days 7 and 14 after administration. This indicates that Fg and/or Fn are not essential for the development of bleomycin-induced pulmonary fibrosis.

The Fas/Fas-ligand system is not required for bleomycin-induced pulmonary fibrosis in mice.

Recent studies suggest that Fas-Fas-ligand (FasL) interactions play an important role in the development of lung injury and fibrosis. However, evidence to support this concept is still indirect. To determine whether Fas-FasL interaction is required for the development of bleomycin-induced pulmonary fibrosis in mice, we used Fas-deficient (lpr) and FasL-deficient (gld ) mice as animal models. After intratracheal instillation of bleomycin, we examined the lungs of mice through bronchoalveolar lavage, histologic studies, DNA nick-end labeling, and hydroxyproline assay. The development of cellular infiltrates, bronchiolar and alveolar epithelial apoptosis, and fibrosis following bleomycin instillation in the lungs in lpr mice and gld mice was similar to their development in wild-type mice. The results of this study show that bleomycin-induced pulmonary fibrosis does not require Fas-FasL interaction, and that epithelial cell apoptosis after bleomycin exposure is mediated by Fas-independent pathways.

The Development of Bleomycin-Induced Pulmonary Fibrosis in Mice Deficient for Components of the Fibrinolytic System

Acute and chronic pulmonary diseases are characterized by impaired fibrinolytic activity within the lung. To determine the role of the fibrinolytic system in regulating the pathologies associated with lung injury, we examined the effect of bleomycin, an agent that induces the development of pulmonary fibrosis, in mice deficient for plasminogen (Pg(-)(/-)), urokinase (u-PA(-)(/-)), urokinase receptor (u-PAR(-)(/-)), or tissue plasminogen activator (t-PA(-)(/-)), and in control wild-type (WT) mice. Pg(-)(/-) and t-PA(-)(/-) mice demonstrated an enhanced increase in lung collagen content relative to that observed in WT mice. Levels in u-PA(-)(/-) and u-PAR(-)(/-) mice were similar to those in WT mice. Histological analysis 14 days after lung injury confirmed enhanced interstitial fibrosis in Pg(-)(/-), u-PA(-)(/-), and t-PA(-)(/-) mice relative to WT and u-PAR(-)(/-) mice. Areas of pulmonary hemorrhage were observed in bleomycin-treated WT mice and not in Pg(-)(/-), u-PA(-)(/-), and u-PAR(-)(/-) mice or saline controls. Instead, extensive areas of fibrosis were present throughout the lungs of bleomycin-treated Pg(-)(/-) and u-PA(-)(/-) mice. A mixed phenotype (hemorrhage and fibrosis) was observed in t-PA(-)(/-) and Pg(+/-) mice. Hemosiderin-laden macrophages were abundant in the lungs of mice exhibiting hemorrhage and these mice were prone to an early death. Enhanced macrophage levels in the lungs and activation of matrix metalloelastase (MMP-12) were found in mice with a hemorrhage phenotype. The results of these studies indicate a role for the fibrinolytic system in acute lung injury and suggests that intra-alveolar hemorrhage is the result of basement membrane degradation through cell-mediated u-PA activation of Pg with possible involvement of matrix metalloproteinases. Absence of these two components of the fibrinolytic system, either urokinase or plasminogen, results in accelerated fibrosis.

IFN-γ-Inducible Protein-10 Attenuates Bleomycin-Induced Pulmonary Fibrosis Via Inhibition of Angiogenesis

AbstractFew studies have addressed the importance of vascular remodeling in the lung during the development of bleomycin-induced pulmonary fibrosis (BPF). For fibroplasia and deposition of extracellular matrix to occur, there must be a geometric increase in neovascularization. We hypothesized that net angiogenesis during the pathogenesis of fibroplasia and deposition of extracellular matrix during BPF are dependent in part on a relative deficiency of the angiostatic CXC chemokine, IFN-γ-inducible protein-10 (IP-10). To test this hypothesis, we measured IP-10 by specific ELISA in whole lung homogenates in either bleomycin-treated or control mice and correlated these levels with lung hydroxyproline. We found that lung tissue from mice treated with bleomycin, compared with that from saline-treated controls, demonstrated a decrease in the presence of IP-10 that was correlated to a greater angiogenic response and total lung hydroxyproline content. Systemic administration of IP-10 significantly reduced BPF without any alteration in lung lymphocyte or NK cell populations. This was also paralleled by a reduction in angiogenesis. Furthermore, IP-10 had no direct effect on isolated pulmonary fibroblasts. These results demonstrate that the angiostatic CXC chemokine, IP-10, inhibits fibroplasia and deposition of extracellular matrix by regulating angiogenesis.

An increase in hyaluronan by lung fibroblasts: a biomarker for intensity and activity of interstitial pulmonary fibrosis?

The purpose of the present study was to clarify the roles of hyaluronan (HA) production of lung fibroblasts in the pathogenesis of pulmonary fibrosis. Quantitative and comparative assessments of the HA levels in bronchoalveolar lavage fluid (BALF) and lung fibroblast-conditioned media (F-CM) were made at various stages during the development of bleomycin-induced pulmonary fibrosis in rats. In bleomycin-treated animals, the HA levels in F-CM increased significantly (P < 0.01) on day 1 after bleomycin treatment, peaked on day 3, and then gradually declined and returned to control values on days 14-28. The HA concentrations of BALF in the bleomycin group were significantly increased (P < 0.01) on day 3, were maximal on day 7, and thereafter gradually decreased, remaining significantly above normal values (P < 0.01) on day 14, but returning to control values by day 28. In the bleomycin group, the HA levels both in BALF and in F-CM were significantly correlated with the cell components in BALF and there was a significant correlation between the HA concentration in BALF and in the F-CM. Lung fibroblasts were activated and produced increased HA which resulted in excessive accumulation of HA in the lung in the early stage of pulmonary fibrosis; the increased HA synthesis of lung fibroblasts and enhanced HA concentrations of BALF might reflect the intensity of alveolitis and the disease activity.

Neutralization of the CXC Chemokine, Macrophage Inflammatory Protein-2, Attenuates Bleomycin-Induced Pulmonary Fibrosis

Few studies have addressed the importance of vascular remodeling in the lung during the development of bleomycin-induced pulmonary fibrosis. For fibroplasia and deposition of extracellular matrix to occur, there must be a geometric increase in neovascularization. We hypothesized that net angiogenesis during the pathogenesis of fibroplasia and deposition of extracellular matrix during bleomycin-induced pulmonary fibrosis are dependent in part upon an overexpression of the angiogenic CXC chemokine, macrophage inflammatory protein-2 (MIP-2). To test this hypothesis, we measured MIP-2 by specific ELISA in whole lung homogenates in either bleomycin-treated or control CBA/J mice and correlated these levels with lung hydroxyproline. We found that lung tissue from mice treated with bleomycin, compared with that from saline-treated controls, demonstrated a significant increase in the presence of MIP-2 that was correlated to a greater angiogenic response and total lung hydroxyproline content. Neutralizing anti-MIP-2 Abs inhibited the angiogenic activity of day 16 bleomycin-treated lung specimens using an in vivo angiogenesis bioassay. Furthermore, when MIP-2 was depleted in vivo by passive immunization, bleomycin-induced pulmonary fibrosis was significantly reduced without a change in the presence of pulmonary neutrophils, fibroblast proliferation, or collagen gene expression. This was also paralleled by a reduction in angiogenesis. These results demonstrate that the angiogenic CXC chemokine, MIP-2, is an important factor that regulates angiogenesis/fibrosis in pulmonary fibrosis.