Lung fibrosis

Oxidative stress plays an important role in the pathogenesis of idiopathic pulmonary fibrosis. Therefore, erdosteine, an antioxidant, is expected to have an inhibitor potential against the disease. Rats were given one dose of bleomycin in pulmonary fibrosis groups and saline in controls. The first dose of oral erdosteine (10 mg/kg/day) was given 2 days before the bleomycin injection to achieve the plateau level in blood and continued until killing. At day 14, fibrotic changes were evaluated, using Aschoft's criteria and lung hydroxyproline content. Bleomycin produced a fivefold increase in fibrosis score that was decreased by 87% by erdosteine (P>0.001) and almost twofold increases in hydroxyproline content which were completely prevented by erdosteine. Myeloperoxidase activities and MDA levels, which were significantly higher in the bleomycin group, were then significantly attenuated by erdosteine. These results revealed that oral erdosteine may prevent the development of acute pulmonary inflammation caused by bleomycin injection via the repression of neutrophil accumulation and lipid peroxidation, resulting in the inhibition of subsequent lung fibrosis.

This study was performed to investigate whether the tamoxifen (TAM) induced the development of pulmonary fibrosis after post-mastectomy cobalt-60 (Co-60) irradiation of chest wall and regional lymphatics in patients with breast cancer along with patient age, menopausal status, body weight, observation time and adjuvant chemotherapy regimens. In this prospective study, 74 patients treated with post-mastectomy adjuvant radiotherapy (RT) and TAM and 37 patients treated with RT were evaluated by axial computerized tomography (CT). CT was first performed before initiation of radiotherapy and TAM treatment. A total of 824 thorax CT sections were evaluated by a radiologist blindly. Comparison of pre-treatment and post-treatment CT sections was used to monitor the development of pulmonary fibrosis. Pulmonary fibrosis developed in 26 of 74 patients who were treated with RT and TAM combination. It was found in five of 37 women treated only with RT. The difference was statistically significant (P<0.01). The median time for the development of pulmonary fibrosis was 8 months in TAM-treated patients whereas it was 10 months in non-TAM-treated patients. Among 111 patients who participated in that study, 65 were in the post-menopausal state and 46 in pre-menopausal state. In the multivariate analysis, the independent prognostic factors were age (P=0.010) and menopausal status (P=0.019). Advanced age and post-menopausal status predisposed to pulmonary fibrosis. The time interval in the development of lung fibrosis and body weight did not significantly influence the results. The time interval which is one independent prognostic factor was found to be associated with lung fibrosis under only-RT group in multivariate analysis (P<0.01). TAM treatment during post-mastectomy RT in breast cancer patients significantly increases the risk of the development of lung fibrosis along with the patient age and menopausal status.

Lung fibrosis is characterized by tissue remodeling resulting from an imbalance between synthesis and degradation of extracellular organic matrices. To examine whether cathepsin(s) (Cat) are important in the development of pulmonary fibrosis, we assessed the expression of four Cat known for their collagenolytic activity in a model of silica-induced lung fibrosis. Different strains of mice were transorally instilled with 2.5 mg crystalline silica or other particles. Cat expression (Cat K, S, L and B) was quantified in lung tissue and isolated pulmonary cells by quantitative RT-PCR. In vitro, we assessed the effect of different cytokines, involved in lung inflammatory and fibrotic responses, on the expression of Cat K by alveolar macrophages and fibroblasts. In lung tissue, Cat K transcript was the most strongly upregulated in response to silica, and this upregulation was intimately related to the fibrotic process. In mouse strains known for their differential response to silica, we s...

ObjectiveConnective tissue growth factor (CTGF; CCN2) is overexpressed in systemic sclerosis (SSc) and has been hypothesized to be a key mediator of the pulmonary fibrosis frequently observed in this disease. CTGF is induced by transforming growth factor β (TGFβ) and is a mediator of some profibrotic effects of TGFβ in vitro. This study was undertaken to investigate the role of CTGF in enhanced expression of type I collagen in bleomycin-induced lung fibrosis, and to delineate the mechanisms of action underlying the effects of CTGF on Col1a2 (collagen gene type I α2) in this mouse model and in human pulmonary fibroblasts.Connective tissue growth factor (CTGF; CCN2) is overexpressed in systemic sclerosis (SSc) and has been hypothesized to be a key mediator of the pulmonary fibrosis frequently observed in this disease. CTGF is induced by transforming growth factor β (TGFβ) and is a mediator of some profibrotic effects of TGFβ in vitro. This study was undertaken to investigate the role of CTGF in enhanced expression of type I collagen in bleomycin-induced lung fibrosis, and to delineate the mechanisms of action underlying the effects of CTGF on Col1a2 (collagen gene type I α2) in this mouse model and in human pulmonary fibroblasts.MethodsTransgenic mice that were carrying luciferase and β-galactosidase reporter genes driven by the Col1a2 enhancer/promoter and the CTGF promoter, respectively, were injected with bleomycin to induce lung fibrosis (or saline as control), and the extracted pulmonary fibroblasts were incubated with CTGF blocking agents. In vitro, transient transfection, promoter/reporter constructs, and electrophoretic mobility shift assays were used to determine the mechanisms of action of CTGF in pulmonary fibroblasts.Transgenic mice that were carrying luciferase and β-galactosidase reporter genes driven by the Col1a2 enhancer/promoter and the CTGF promoter, respectively, were injected with bleomycin to induce lung fibrosis (or saline as control), and the extracted pulmonary fibroblasts were incubated with CTGF blocking agents. In vitro, transient transfection, promoter/reporter constructs, and electrophoretic mobility shift assays were used to determine the mechanisms of action of CTGF in pulmonary fibroblasts.ResultsIn the mouse lung tissue, CTGF expression and promoter activity peaked 1 week after bleomycin challenge, whereas type I collagen expression and Col1a2 promoter activity peaked 2 weeks postchallenge. Fibroblasts isolated from the mouse lungs 14 days after bleomycin treatment retained a profibrotic expression pattern, characterized by greatly elevated levels of type I collagen and CTGF protein and increased promoter activity. In vitro, inhibition of CTGF by specific small interfering RNA and neutralizing antibodies reduced the collagen protein expression and Col1a2 promoter activity. Moreover, in vivo, anti-CTGF antibodies applied after bleomycin challenge significantly reduced the Col1a2 promoter activity by ∼25%. The enhanced Col1a2 promoter activity in fibroblasts from bleomycin-treated lungs was partly dependent on Smad signaling, whereas CTGF acted on the Col1a2 promoter by a mechanism that was independent of the Smad binding site, but was, instead, dependent on the ERK-1/2 and JNK MAPK pathways. The CTGF effect was mapped to the proximal promoter region surrounding the inverted CCAAT box, possibly involving CREB and c-Jun. In human lung fibroblasts, the human COL1A2 promoter responded in a similar manner, and the mechanisms of action also involved ERK-1/2 and JNK signaling.In the mouse lung tissue, CTGF expression and promoter activity peaked 1 week after bleomycin challenge, whereas type I collagen expression and Col1a2 promoter activity peaked 2 weeks postchallenge. Fibroblasts isolated from the mouse lungs 14 days after bleomycin treatment retained a profibrotic expression pattern, characterized by greatly elevated levels of type I collagen and CTGF protein and increased promoter activity. In vitro, inhibition of CTGF by specific small interfering RNA and neutralizing antibodies reduced the collagen protein expression and Col1a2 promoter activity. Moreover, in vivo, anti-CTGF antibodies applied after bleomycin challenge significantly reduced the Col1a2 promoter activity by ∼25%. The enhanced Col1a2 promoter activity in fibroblasts from bleomycin-treated lungs was partly dependent on Smad signaling, whereas CTGF acted on the Col1a2 promoter by a mechanism that was independent of the Smad binding site, but was, instead, dependent on the ERK-1/2 and JNK MAPK pathways. The CTGF effect was mapped to the proximal promoter region surrounding the inverted CCAAT box, possibly involving CREB and c-Jun. In human lung fibroblasts, the human COL1A2 promoter responded in a similar manner, and the mechanisms of action also involved ERK-1/2 and JNK signaling.ConclusionOur results clearly define a direct profibrotic effect of CTGF and demonstrate its contribution to lung fibrosis through transcriptional activation of Col1a2. Blocking strategies revealed the signaling mechanisms involved. These findings show CTGF to be a rational target for therapy in fibrotic diseases such as SSc.Our results clearly define a direct profibrotic effect of CTGF and demonstrate its contribution to lung fibrosis through transcriptional activation of Col1a2. Blocking strategies revealed the signaling mechanisms involved. These findings show CTGF to be a rational target for therapy in fibrotic diseases such as SSc.

Despite substantial progress, mortality and morbidity of the acute respiratory distress syndrome (ARDS), a severe form of acute lung injury (ALI), remain unacceptably high. There is no effective treatment for ARDS/ALI. The renin-angiotensin system (RAS) through Angiotensin-converting enzyme (ACE)-generated Angiotensin II contributes to lung injury. ACE2, a recently discovered ACE homologue, acts as a negative regulator of the RAS and counterbalances the function of ACE. We hypothesized that ACE2 prevents Bleomycin (BLM)-induced lung injury. Fourteen to 16-week-old ACE2 knockout mice-male (ACE2(-/y)) and female (ACE2(-/-))-and age-matched wild-type (WT) male mice received intratracheal BLM (1.5U/kg). Male ACE2(-/y) BLM injured mice exhibited poorer exercise capacity, worse lung function and exacerbated lung fibrosis and collagen deposition compared with WT. These changes were associated with increased expression of the profibrotic genes α-smooth muscle actin (α-SMA) and Transforming ...

Oxidative stress has been implicated in the pathogenesis of bleomycin-induced lung fibrosis and many antioxidant agents have been studied for prevention and treatment of the disease in animals and humans. We therefore examined whether Ginkgo biloba (Gb), a flavonoid-rich antioxidant, inhibits bleomycin-induced lung fibrosis in rats. Male Spraque–Dawley rats were given a single dose of bleomycin (2.5 mg/kg, intratracheally) in pulmonary fibrosis groups and saline in controls. First dose of Gb was given a day before the bleomycin injection and continued until sacrifice. At day 14, fibrotic changes in lung were estimated to occur by Aschoft's criteria and lung hydroxyproline content. Bleomycin challenge provoked severe pulmonary fibrosis with marked increase in hydroxyproline content of lung tissue and typical histological findings, which is prevented by Gb. Hydroxyproline level was significantly higher (13.51 ± 0.87 mg/g dried tissue) in bleomycin treated rats than controls (9.2 ± 1.33), and its level was remained to the control levels (7.38 ± 0.76) in rats treated with prophylactic Gb. On the other hand, bleomycin injection significantly reduced activities of glutathione peroxidase, superoxide dismutase and catalase in lung tissue which is prevented by Gb. Also, bleomycin injection resulted in a marked increase of malondialdehyde and nirite level which is attenuated by Gb. The data suggest that Gb has a potent antioxidant activity in the model of bleomycin-induced lung fibrosis in rats, and therefore has a potent antifibrotic activity against bleomycin-induced lung fibrosis model in rats.

It has been generally well accepted that chronic inflammation is a necessary component of lung fibrosis but this concept has recently been challenged. Using biochemical, histological, immunohistochemistry, and cellular analyses, we compared the lung responses (inflammation and fibrosis) to fibrogenic silica particles (2.5 and 25 mg/g lung) in Sprague-Dawley rats and NMRI mice. Rats treated with silica particles developed chronic and progressive inflammation accompanied by an overproduction of TNF-alpha as well as an intense lung fibrosis. Dexamethasone or pioglitazone limited the amplitude of the lung fibrotic reaction to silica in rats, supporting the paradigm that inflammation drives lung fibrosis. In striking contrast, in mice, silica induced only a limited and transient inflammation without TNF-alpha overproduction. However, mice developed lung fibrosis of a similar intensity than rats. The fibrotic response in mice was accompanied by a high expression of the anti-inflammatory a...