Oxidative stress in pulmonary fibrosis: a possible role for redox modulatory therapy

TGF-β1 stimulates HDAC4 nucleus-to-cytoplasm translocation and NADPH oxidase 4-derived reactive oxygen species in normal human lung fibroblasts

Myofibroblasts are important mediators of fibrogenesis; thus blocking fibroblast-to-myofibroblast differentiation (FMD) may be an effective strategy to treat pulmonary fibrosis (PF). Previously, we reported that histone deacetylase 4 (HDAC4) activity is necessary for transforming growth factor-β1 (TGF-β1)-induced human lung FMD. Here, we show that TGF-β1 increases NADPH oxidase 4 (NOX4) mRNA and protein expression in normal human lung fibroblasts (NHLFs) and causes nuclear export of HDAC4. Application of the NOX family inhibitor diphenyleneiodonium chloride reduces TGF-β1-induced HDAC4 nuclear export, expression of the myofibroblast marker α-smooth muscle actin (α-SMA), and α-SMA fiber formation. Inhibition of HDAC4 nucleus-to-cytoplasm translocation using leptomycin B (LMB) had little effect on α-SMA expression but blocked α-SMA fiber formation. A coimmunoprecipitation assay showed that HDAC4 associates with α-SMA. Moreover, LMB abolishes TGF-β1-induced α-SMA fiber formation and cell contraction. Relevant to human pulmonary fibrosis, idiopathic PF specimens showed significantly higher NOX4 RNA expression and scant HDAC4 staining within nuclei of fibroblast foci myofibroblasts. Taken together, these results indicate that reactive oxygen species promote TGF-β1-mediated myofibroblast differentiation and HDAC4 nuclear export. The physical association of HDAC4 with α-SMA suggests that HDAC4 has a role in regulating the α-SMA cytoskeleton arrangement.

Sulforaphane prevents bleomycin‑induced pulmonary fibrosis in mice by inhibiting oxidative stress via nuclear factor erythroid 2‑related factor‑2 activation

Lung fibrosis is associated with inflammation, apoptosis and oxidative damage. The transcription factor nuclear factor erythroid 2-related factor-2 (Nrf2) prevents damage to cells from oxidative stress by regulating the expression of antioxidant proteins. Sulforaphane (SFN), an Nrf2 activator, additionally regulates excessive oxidative stress by promoting the expression of endogenous antioxidants. The present study investigated if SFN protects against lung injury induced by bleomycin (BLM). The secondary aim of the present study was to assess if this protection mechanism involves upregulation of Nrf2 and its downstream antioxidants. Pulmonary fibrosis was induced in C57/BL6 mice by intratracheal instillation of BLM. BLM and age-matched control mice were treated with or without a daily dose of 0.5 mg/kg SFN until sacrifice. On days 7 and 28, mice were assessed for induction of apoptosis, inflammation, fibrosis, oxidative damage and Nrf2 expression in the lungs. The lungs were investigated with histological techniques including haematoxylin and eosin staining, Masson's trichrome staining and terminal deoxynucleotidyl transferase UTP nick end labeling. Inflammatory, fibrotic and apoptotic processes were confirmed by western blot analysis for interleukin-1β, tumor necrosis factor-α, transforming growth factor-β and caspase-3 protein expressions. Furthermore, protein levels of 3-nitro-tyrosine, 4-hydroxynonenal, superoxide dismutase 1 and catalase were investigated by western blot analysis. It was demonstrated that pulmonary fibrosis induced by BLM significantly increased apoptosis, inflammation, fibrosis and oxidative stress in the lungs at days 7 and 28. Notably, SFN treatment significantly attenuated the infiltration of the inflammatory cells, collagen accumulation, epithelial cell apoptosis and oxidative stress in the lungs. In addition, SFN treatment increased expression of the Nrf2 gene and its downstream targets. In conclusion, these results suggested that SFN treatment of pulmonary fibrosis mouse models may attenuate alveolitis, fibrosis, apoptosis and lung oxidative stress by increasing the expression of antioxidant enzymes, including NAPDH quinone oxidoreductase, heme oxygenase-1, superoxide dismutase and catalase, via upregulation of Nrf2 gene expression. Thus, the results from the present study may facilitate the development of therapies for BLM-toxicity and pulmonary fibrosis.

Regulation of Nitrogen Mustard-Induced Lung Macrophage Activation by Valproic Acid, a Histone Deacetylase Inhibitor

Nitrogen mustard (NM)-induced lung injury is associated with an accumulation of proinflammatory/cytotoxic M1 and antiinflammatory/wound repair M2 macrophages, which have been implicated in tissue injury and repair. Herein, we analyzed the effects of valproic acid (VPA), a histone deacetylase (HDAC) inhibitor with antiinflammatory and antioxidant activity, on lung macrophages responding to NM. Treatment of rats with NM (0.125 mg/kg, i.t.) resulted in structural alterations in the lung and a macrophage-rich inflammatory cell infiltrate, at 3 d and 7 d. This was accompanied by expression of PCNA, a marker of proliferation, and CYPb5, HO-1, and MnSOD, markers of oxidative stress. Administration of VPA (300 mg/kg/day; i.p.), beginning 30 min after NM, reduced increases in PCNA, CYPb5, HO-1, and MnSOD. This was associated with increases in immature CD11b+CD43+ M1 macrophages in the lung, and decreases in mature CD11b+CD43- M2 macrophages 3 d post NM, suggesting delayed maturation and phenotypic switching. VPA also attenuated NM-induced increases in lung iNOS+ and CCR2+ M1 macrophages, a response correlated with downregulation of NOS2, IL12B, PTGS2, MMP-9, and CCR2 expression. Conversely, numbers of CD68+, CD163+ , and ATR-1α+ M2 macrophages increased after VPA, along with the expression of IL10, ApoE, and ATR-1A. NM exposure resulted in increased HDAC activity and upregulation of HDAC2 and acetylated H3K9 in the lung. Whereas VPA blunted the effects of NM on HDAC2 expression, histone H3K9 acetylation increased. These data suggest that alterations in the balance between histone acetylases and deacetylases contribute to lung macrophage maturation and activation following NM exposure.

Dust particles-induced intracellular Ca2+ signaling and reactive oxygen species in lung fibroblast cell line MRC5

Epidemiologic interest in particulate matter (PM) is growing particularly because of its impact of respiratory health. It has been elucidated that PM evoked inflammatory signal in pulmonary epithelia. However, it has not been established Ca²⁺ signaling mechanisms involved in acute PM-derived signaling in pulmonary fibroblasts. In the present study, we explored dust particles PM modulated intracellular Ca²⁺ signaling and sought to provide a therapeutic strategy by antagonizing PM-induced intracellular Ca²⁺ signaling in human lung fibroblasts MRC5 cells. We demonstrated that PM10, less than 10 µm, induced intracellular Ca²⁺ signaling, which was mediated by extracellular Ca²⁺. The PM10-mediated intracellular Ca²⁺ signaling was attenuated by antioxidants, phospholipase blockers, polyADPR polymerase 1 inhibitor, and transient receptor potential melastatin 2 (TRPM2) inhibitors. In addition, PM-mediated increases in reactive oxygen species were attenuated by TRPM2 blockers, clotrimazole (CLZ) and N-(p-amylcinnamoyl) anthranilic acid (ACA). Our results showed that PM10 enhanced reactive oxygen species signal by measuring DCF fluorescence and the DCF signal attenuated by both TRPM2 blockers CLZ and ACA. Here, we suggest functional inhibition of TRPM2 channels as a potential therapeutic strategy for modulation of dust particle-mediated signaling and oxidative stress accompanying lung diseases.

Attenuation of Bleomycin-Induced Pulmonary Fibrosis in Rats with S-Allyl Cysteine

Pulmonary fibrosis is a complex disease with high mortality and morbidity. As there are currently no effective treatments, development of new strategies is essential for improving therapeutic outcomes. S-allyl cysteine (SAC) is a constituent of aged garlic extract that has demonstrated efficacy as an antioxidant and anti-inflammatory agent. The current study examines the effects of SAC on pulmonary fibrosis induced by a single intratracheal instillation of bleomycin (2.5 mg/kg). SAC was administered to rats as 0.15% SAC-containing diet from seven days prior to instillation up until the conclusion of the experiment (14 days post-instillation). SAC significantly reduced collagen mRNA expression and protein deposition (33.3 ± 2.7 μg/mg and 28.2 ± 2.1 μg/mg tissue in vehicle- and SAC-treated rats, respectively), and decreased fibrotic area, as assessed histologically. In the rats’ lungs, SAC also attenuated the increased expression of transforming growth factor-β1 (TGF-β1), a central regulator of myofibroblast recruitment, activation, and differentiation. While bleomycin instillation increased the number of myofibroblasts within the lung mesenchymal area, this change was significantly reduced by SAC treatment. SAC may exert efficacy as an anti-fibrotic by attenuating myofibroblast differentiation through TGF-β1-mediated fibroproliferative processes. Thus, our results indicate SAC may be useful for the prevention or treatment of pulmonary fibrosis.

Bach1 siRNA attenuates bleomycin-induced pulmonary fibrosis by modulating oxidative stress in mice

Oxidative stress plays an essential role in inflammation and fibrosis. Bach1 is an important transcriptional repressor that acts by modulating oxidative stress and represents a potential target in the treatment of pulmonary fibrosis (PF). In this study, we knocked down Bach1 using adenovirus-mediated small interfering RNA (siRNA) to determine whether the use of Bach1 siRNA is an effective therapeutic strategy in mice with bleomycin (BLM)‑induced PF. Mouse lung fibroblasts (MLFs) were incubated with transforming growth factor (TGF)-β1 (5 ng/ml) and subsequently infected with recombined adenovirus-like Bach1 siRNA1 and Bach1 siRNA2, while an empty adenovirus vector was used as the negative control. The selected Bach1 siRNA with higher interference efficiency was used for the animal experiments. A mouse model of BLM-induced PF was established, and Bach1 siRNA (1x109 pfu) was administered to the mice via the tail vein. The results revealed that the Bach1 mRNA and protein levels were significantly downregulated by Bach1 siRNA. Furthermore, the MLFs infected with Bach1 siRNA exhibited increased mRNA and protein expression levels of heme oxygenase-1 and glutathione peroxidase 1, but decreased levels of TGF-β1 and interleukin-6 in the cell supernatants compared with the cells exposed to TGF-β1 alone. Bach1 knockdown by siRNA also enhanced the expression of antioxidant factors, but suppressed that of fibrosis‑related cytokines in mice compared with the BLM group. Finally, the inflammatory infiltration of alveolar and interstitial cells and the destruction of lung structure were significantly attenuated in the mide administered Bach1 siRNA compared with those in the BLM group. On the whole, our findings demonstrate that Bach1 siRNA exerts protective effects against BLM-induced PF in mice. Our data may provide the basis for the development of novel targeted therapeutic strategies for PF.

MnTBAP Inhibits Bleomycin-Induced Pulmonary Fibrosis by Regulating VEGF and Wnt Signaling

Cellular oxidative stress is implicated not only in lung injury but also in contributing to the development of pulmonary fibrosis. We demonstrate that a cell-permeable superoxide dismutase (SOD) mimetic and peroxynitrite scavenger, manganese (III) tetrakis (4-benzoic acid) porphyrin chloride (MnTBAP) significantly inhibited bleomycin-induced fibrogenic effects both in vitro and in vivo. Further investigation into the underlying mechanisms revealed that MnTBAP targets canonical Wnt and non-canonical Wnt/Ca2+ signaling pathways, both of which were upregulated by bleomycin treatment. The effect of MnTBAP on canonical Wnt signaling was significant in vivo but inconclusive in vitro and the non-canonical Wnt/Ca2+ signaling pathway was observed to be the predominant pathway regulated by MnTBAP in bleomycin-induced pulmonary fibrosis. Furthermore, we show that the inhibitory effects of MnTBAP involve regulation of VEGF which is upstream of the Wnt signaling pathway. Overall, the data show that the superoxide scavenger MnTBAP attenuates bleomycin-induced pulmonary fibrosis by targeting VEGF and Wnt signaling pathways. J. Cell. Physiol. 232: 506-516, 2017. © 2016 Wiley Periodicals, Inc.

Baicalin attenuates bleomycin-induced pulmonary fibrosis via adenosine A2a receptor related TGF-β1-induced ERK1/2 signaling pathway

BACKGROUND

Baicalin has been reported to have anti-fibrosis effect; however, its mechanism still remains to be elucidated. Adenosine A2a receptor (A2aR) is a novel inflammation regulator, and transforming growth factor-β1 (TGF-β1)-induced extracellular signal regulated kinase1/2 (ERK1/2) signaling pathway plays an important role in idiopathic pulmonary fibrosis (IPF). This study was to explore the relationship of A2aR and TGF-β1-induced ERK1/2 in bleomycin (BLM)-induced pulmonary fibrosis in mice, and to investigate whether A2aR mediate the anti-fibrosis effect of Baicalin on BLM-induced pulmonary fibrosis.

METHODS

The A2aR-/- and A2aR+/+ mice were respectively divided into three groups: control group, model group, baicalin group. Pulmonary fibrosis was induced in mice of model groups by intratracheal instillation of bleomycin, and baicalin was administered in mice of baicalin groups daily for 28 days. Histopathological and ultrastructural changes of lung tissues were evaluated. Lung coefficient and the levels of hydroxyproline (HYP) in lung tissues were measured at the same time. The levels of serum TGF-β1 were measured by ELISA. The expression of TGF-β1, ERK1/2, p-ERK1/2 and A2aR were detected by western blot and immunohistochemical staining techniques.

RESULTS

Severe lung fibrosis was observed in the bleomycin-treated mice on day 28. The histopathological findings and collagen content of lung tissues were much severer/higher in A2aR-/- mice than in A2aR+/+ mice. We also showed that TGF-β1 and p-ERK1/2 were upregulated in bleomycin-treated mice and expressed higher in A2aR-/- mice compared to A2aR+/+ mice. Besides, bleomycin-treated A2aR+/+ mice had increased A2aR level in lungs. However, long-term treatment with baicalin in A2aR-/- and A2aR+/+ mice significantly ameliorated the histopathological changes in lungs. Moreover, Increased TGF-β1 and p-ERK1/2 expressions in bleomycin-treated A2aR-/- and A2aR+/+ mice were obviously diminished by baicalin. The baicalin-treated A2aR-/- mice had severer lung fibrosis and higher expressions of TGF-β1 and p-ERK1/2 than A2aR+/+ mice. Baicalin has also upregulated the expression of A2aR in A2aR+/+ mice.

CONCLUSIONS

Genetic inactivation of A2aR exacerbated the pathological processes of bleomycin-induced pulmonary fibrosis. Together, baicalin could inhibit BLM-induced pulmonary fibrosis by upregulating A2aR, suggesting A2aR as a therapeutic target of baicalin for the treatment of pulmonary fibrosis.

Sarcandra glabra combined with lycopene protect rats from lipopolysaccharide induced acute lung injury via reducing inflammatory response

Sarcandra glabra (Chinese name, Zhongjiefeng) is an important herb widely used in traditional Chinese medicine. Lycopene has been shown to be a powerful antioxidant. This study aims to test the hypothesis that Sarcandra glabra combined with lycopene protect rats from lipopolysaccharide (LPS) induced acute lung injury (ALI). Metabolomics approach combined with pathological inspection, serum biochemistry examination, enzyme-linked immunosorbent assay and western blotting were used to explore the protective effects of Sarcandra glabra and lycopene on LPS-induced ALI, and to elucidate the underlying mechanisms. Results showed that Sarcandra glabra and lycopene could significantly ameliorate LPS-induced histopathological injuries, improve the anti-oxidative activities of rats, decrease the levels of TNF-α and IL-6, suppress the activations of MAPK and transcription factor NF-κB and reverse the disturbed metabolism towards the normal status. Taken together, this integrated study revealed that Sarcandra glabra combined with lycopene had great potential in protecting rats from LPS-induced ALI, which would be helpful to guide the clinical medication.

Oxidative Modifications of Protein Tyrosyl Residues Are Increased in Plasma of Human Subjects with Interstitial Lung Disease

RATIONALE

Interstitial lung diseases (ILDs) are associated with oxidative stress. Plasma biomarkers that are directly linked to oxidative stress responses in this disease have not been identified. Stable oxidation products of tyrosine residues in proteins may reflect the oxidative microenvironment in the lung or a systemic inflammatory state.

OBJECTIVES

To determine if levels of protein tyrosine oxidation are elevated in plasma of patients with ILD compared with an age- and sex-matched healthy control cohort.

METHODS

Three tyrosine oxidation products (3-chlorotyrosine, 3-nitrotyrosine, and o,o'-dityrosine) were quantified by tandem mass spectrometry in cellular models, a mouse model of injury-induced fibrosis, and in plasma of healthy control subjects and patients with ILD (n = 42 in each group).

MEASUREMENTS AND MAIN RESULTS

Plasma levels of 3-chlorotyrosine, 3-nitrotyrosine, and o,o'-dityrosine were markedly elevated in patients with ILD compared with control subjects with receiver operating characteristic curves separating these groups of 0.872, 0.893, and 0.997, respectively. In a murine model of lung fibrosis, levels of all three oxidative tyrosine modifications were increased in plasma and lung tissue. Cellular models support a critical role for a heme peroxidase and enzymatic sources of reactive oxygen species in the generation of these oxidized products.

CONCLUSIONS

We demonstrate an increase in oxidized tyrosine moieties within proteins in the circulating plasma of patients with ILD. These data support the potential for development of oxidative stress-related biomarkers in early diagnosis, prognostication, and/or in evaluating responsiveness to emerging therapies for ILD.

D-4F, an apolipoprotein A-I mimetic, inhibits TGF-β1 induced epithelial-mesenchymal transition in human alveolar epithelial cell

Emerging evidences support that transforming growth factor β1 (TGF-β1) induced epithelial-mesenchymal transition (EMT) participates in the pathogenesis of pulmonary fibrosis and asthmatic airway remodeling. Recent studies demonstrated that apolipoprotein A-I (Apo A-I) is the only known substance that can resolve established pulmonary fibrotic nodules, and Apo A-I mimetic D-4F (a synthetic polypeptide consisting of 18 amino acids) plays an inhibitory role in murine asthmatic model. However, cellular mechanisms for such therapeutic effects of Apo A-I and D-4F remain to be elucidated. This study evaluated the effects of D-4F on TGF-β1 induced EMT in human type II alveolar epithelial cell line A549. A549 cells treated with 10ng/ml of TGF-β1 manifested distinct EMT, including fibroblastic morphological changes, down-regulation of epithelial marker E-cadherin and up-regulation of mesenchymal marker vimentin. These EMT related changes were all inhibited by D-4F in a concentration dependent manner. Transcriptional investigation demonstrated clearly that D-4F dose-dependently compensated for the reduced E-cadherin mRNA level and the increased vimentin mRNA level in TGF-β1 treated A549 cells. Translational analysis revealed that D-4F significantly reversed the TGF-β1 induced changes of E-cadherin and vimentin levels. These results suggested that D-4F inhibits TGF-β1 induced EMT in human alveolar epithelial cell. Given the functional similarities between D-4F and Apo A-I, it is speculated that D-4F and Apo A-I are able to exert possible anti-fibrotic and anti-asthmatic effects via inhibiting alveolar EMT, and D-4F may possess beneficial clinical potential for patients suffering from pulmonary fibrosis and asthma.

Mast cells and their activation in lung disease

Mast cells and their activation contribute to lung health via innate and adaptive immune responses to respiratory pathogens. They are also involved in the normal response to tissue injury. However, mast cells are involved in disease processes characterized by inflammation and remodeling of tissue structure. In these diseases mast cells are often inappropriately and chronically activated. There is evidence for activation of mast cells contributing to the pathophysiology of asthma, pulmonary fibrosis, and pulmonary hypertension. They may also play a role in chronic obstructive pulmonary disease, acute respiratory distress syndrome, and lung cancer. The diverse mechanisms through which mast cells sense and interact with the external and internal microenvironment account for their role in these diseases. Newly discovered mechanisms of redistribution and interaction between mast cells, airway structural cells, and other inflammatory cells may offer novel therapeutic targets in these disease processes.

Redox mechanisms in age-related lung fibrosis

Redox signaling and oxidative stress are associated with tissue fibrosis and aging. Aging is recognized as a major risk factor for fibrotic diseases involving multiple organ systems, including that of the lung. A number of oxidant generating enzymes are upregulated while antioxidant defenses are deficient with aging and cellular senescence, leading to redox imbalance and oxidative stress. However, the precise mechanisms by which redox signaling and oxidative stress contribute to the pathogenesis of lung fibrosis are not well understood. Tissue repair is a highly regulated process that involves the interactions of several cell types, including epithelial cells, fibroblasts and inflammatory cells. Fibrosis may develop when these interactions are dysregulated with the acquisition of pro-fibrotic cellular phenotypes. In this review, we explore the roles of redox mechanisms that promote and perpetuate fibrosis in the context of cellular senescence and aging.

Resveratrol attenuates hyperoxia-induced oxidative stress, inflammation and fibrosis and suppresses Wnt/β-catenin signalling in lungs of neonatal rats

Although survival rate of infants born prematurely has been raised by supplemental oxygen treatment, it is followed by high morbidity of hyperoxia-induced bronchopulmonary dysplasia. In this study, the effect of resveratrol on the lung injury was evaluated in hyperoxia-exposed rats of preterm birth. The results demonstrated that hyperoxia led to thickened alveolar wall, simplified alveolar architecture and fibrosis. In addition, elevated methane dicarboxylic aldehyde level, decreased glutathione level and superoxide dismutase activity were also found in hyperoxic lungs, as well as the increased tumor necrosis factor-α, interleukin-1β and interleukin-6 in the bronchoalveolar lavage fluid. Fibrotic-associated proteins transforming growth factor-β1, α-smooth muscle actin, collagen I and fibronectin deposition were also found in interstitial substance of lungs. Furthermore, Wnt/β-catenin signalling was found to be active in hyperoxia-induced lungs. In addition, expression of SP-C was increased and T1α was decreased in hyperoxia-exposed lungs. Resveratrol intraperitoneal administration alleviated hyperoxia-induced histological injury of lungs, regulated redox balance, decreased pro-inflammatory cytokine release, and down-regulated expression of fibrotic-associated proteins. Furthermore, Wnt/β-catenin signalling was also suppressed by resveratrol, as represented by diminished expression of lymphoid enhancer factor-1, Wnt induced signalling protein-1 and cyclin D1. In addition, the increase of SP-C and decrease of T1α expression was prevented as well. The present study showed that resveratrol could protect lungs from hyperoxia-induced injury through its antioxidant, anti-inflammatory and anti-fibrotic effects. The transdifferentiation of alveolar epithelial type II cells to alveolar epithelial type I cells promotion and Wnt/β-catenin signalling suppression are also involved in the protective effect.

Nitric oxide mediates bleomycin-induced angiogenesis and pulmonary fibrosis via regulation of VEGF

Pulmonary fibrosis is a progressive lung disease hallmarked by increased fibroblast proliferation, amplified levels of extracellular matrix deposition and increased angiogenesis. Although dysregulation of angiogenic mediators has been implicated in pulmonary fibrosis, the specific rate-limiting angiogenic markers involved and their role in the progression of pulmonary fibrosis remains unclear. We demonstrate that bleomycin treatment induces angiogenesis, and inhibition of the central angiogenic mediator VEGF using anti-VEGF antibody CBO-P11 significantly attenuates bleomycin-induced pulmonary fibrosis in vivo. Bleomycin-induced nitric oxide (NO) was observed to be the key upstream regulator of VEGF via the PI3k/Akt pathway. VEGF regulated other important angiogenic proteins including PAI-1 and IL-8 in response to bleomycin exposure. Inhibition of NO and VEGF activity significantly mitigated bleomycin-induced angiogenic and fibrogenic responses. NO and VEGF are key mediators of bleomycin-induced pulmonary fibrosis, and could serve as important targets against this debilitating disease. Overall, our data suggests an important role for angiogenic mediators in the pathogenesis of bleomycin-induced pulmonary fibrosis.

Relationship between plasma matrix metalloproteinase levels, pulmonary function, bronchodilator response, and emphysema severity

Objective

Chronic obstructive pulmonary disease (COPD) is characterized by chronic inflammation in the airway and lung. A protease–antiprotease imbalance has been suggested as a possible pathogenic mechanism for COPD. We evaluated the relationship between matrix metalloproteinase (MMP) levels and COPD severity.

Methods

Plasma levels of MMP-1, MMP-8, MMP-9, and MMP-12 were measured in 57 COPD patients and 36 normal controls. The relationship between MMP levels and lung function, emphysema index, bronchial wall thickness, pulmonary artery pressure, and quality of life was examined using general linear regression analyses.

Results

There were significant associations of MMP-1 with bronchodilator reversibility and of MMP-8 and MMP-9 with lung function. Also, MMP-1, MMP-8, and MMP-9 levels were correlated with the emphysema index, independent of lung function. However, MMP-12 was not associated with lung function or emphysema severity. Associations between MMP levels and bronchial wall thickness, pulmonary artery pressure, and quality of life were not statistically significant.

Conclusion

Plasma levels of MMP-1, MMP-8, and MMP-9 are associated with COPD severity and can be used as a biomarker to better understand the characteristics of COPD patients.

Aliskiren attenuates bleomycin-induced pulmonary fibrosis in rats: focus on oxidative stress, advanced glycation end products, and matrix metalloproteinase-9

Pulmonary fibrosis is a progressive lung disorder with high mortality rate and limited successful treatment. This study was designed to assess the potential anti-oxidant and anti-fibrotic effects of aliskiren (Alsk) during bleomycin (BLM)-induced pulmonary fibrosis. Male Wistar rats were used as control untreated or treated with the following: a single dose of 2.5 mg/kg of BLM endotracheally and BLM and Alsk (either low dose 30 mg/kg/day or high dose 60 mg/kg/day), and another group was given Alsk 60 mg/kg/day alone. Alsk was given by gavage. Alsk anti-oxidant and anti-fibrotic effects were assessed. BLM significantly increased relative lung weight and the levels of lactate dehydrogenase and total and differential leucocytic count in bronchoalveolar lavage that was significantly ameliorated by high-dose Alsk treatment. As markers of oxidative stress, BLM caused a significant increase in the levels of lipid peroxides and nitric oxide accompanied with a significant decrease of superoxide dismutase and glutathione transferase enzymes. High-dose Alsk treatment restored these markers toward normal values. Alsk counteracted the overexpression of advanced glycation end products, matrix metalloproteinase-9 (MMP-9), and tissue inhibitor of metalloproteinases-1 in lung tissue induced by BLM. Fibrosis assessed by measuring hydroxyproline content, which markedly increased in the BLM group, was also significantly reduced by Alsk. These were confirmed by histopathological and immunohistochemical examination which revealed that Alsk attenuates signs of pulmonary fibrosis and decreased the overexpressed MMP-9 and transforming growth factor β1. Collectively, these findings indicate that Alsk has a potential anti-fibrotic effect beside its anti-oxidant activity.

Metabolic Profiling Regarding Pathogenesis of Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive, eventually fatal disease characterized by fibrosis of the lung parenchyma and loss of lung function. IPF is believed to be caused by repetitive alveolar epithelial cell injury and dysregulated repair process including uncontrolled proliferation of lung (myo) fibroblasts and excessive deposition of extracellular matrix proteins in the interstitial space; however, the pathogenic pathways involved in IPF have not been fully elucidated. In this study, we attempted to characterize metabolic changes of lung tissues involved in the pathogenesis of IPF using gas chromatography-mass spectrometry-based metabolic profiling. Partial least-squares discriminant analysis (PLS-DA) model generated from metabolite data was able to discriminate between the control subjects and IPF patients (R(2)X = 0.37, R(2)Y = 0.613 and Q(2) (cumulative) = 0.54, receiver operator characteristic AUC > 0.9). We discovered 25 metabolite signatures of IPF using both univariate and multivariate statistical analyses (FDR < 0.05 and VIP score of PLS-DA > 1). These metabolite signatures indicated alteration in metabolic pathways: adenosine triphosphate degradation pathway, glycolysis pathway, glutathione biosynthesis pathway, and ornithine aminotransferase pathway. The results could provide additional insight into understanding the disease and potential for developing biomarkers.

Effect of inhaled N-acetylcysteine monotherapy on lung function and redox balance in idiopathic pulmonary fibrosis

BACKGROUND

An oxidant-antioxidant imbalance is considered to be involved in the pathogenesis of idiopathic pulmonary fibrosis (IPF). Therefore, administration of antioxidants, such as N-acetylcysteine (NAC), may represent a potential treatment option for IPF patients.

METHODS

The aim of this study was to evaluate the effect of inhaled NAC monotherapy on lung function and redox balance in patients with IPF. A retrospective observational study was done, involving 22 patients with untreated early IPF (19 men; mean [±S.D.] age, 71.8 [±6.3]y). At baseline and at 6 and 12 months after initiating inhaled NAC monotherapy, we assessed forced vital capacity (FVC) and measured the levels of total glutathione, oxidized glutathione (GSSG), and the ratio of reduced to oxidized glutathione in whole blood (hereafter referred to as the ratio), and of 8-hydroxy-2'-deoxyguanosine in urine. To evaluate response to treatment, we defined disease progression as a decrease in FVC of ≥5% from baseline and stable disease as a decrease in FVC of <5%, over a period of 6 months.

RESULTS

Change in FVC in the stable group at 6 and 12 months were 95±170mL and -70±120mL, while those in the progressive group at 6 and 12 months were -210±80mL, -320±350mL, respectively. The serial mean change in GSSG from baseline decreased as the ratio of reduced to oxidized glutathione increased in patients with stable disease, while it increased as this ratio decreased in patients with progressive disease. Receiver operating characteristic curve analysis revealed that a baseline GSSG level of ≥1.579μM was optimal for identifying treatment responders.

CONCLUSION

Inhaled NAC monotherapy was associated with improved redox imbalance in patients with early IPF.

Apigenin protects against bleomycin-induced lung fibrosis in rats

Apigenin is a non-toxic and non-mutagenic flavone that exists abundantly in numerous herbs and vegetables. Apigenin exerts anti-proliferative and anti-inflammatory properties. The aim of the present study was to investigate the effects of apigenin on bleomycin-induced lung fibrosis in rats. A single intratracheal instillation of bleomycin (5 mg/kg) was administered and rats were sacrificed on 7 and 28 days post bleomycin instillation. The instillation of bleomycin resulted in decreased body weight and an increase in the lung index. In addition, bleomycin administration increased the hydroxyproline content, myeloperoxidase (MPO) activity, tumor necrosis factor (TNF)-α and transforming growth factor (TGF)-β levels and decreased the superoxide dismutase (SOD) activity in the rat lung tissues. Excessive collagen deposits were detected in the lung tissues in bleomycin-treated rats compared with normal control rats. Notably, the oral administration of apigenin (10, 15 and 20 mg/kg/day) appeared to prevent the fibrotic process. The treatment suppressed the increases in hydroxyproline content, MPO activity, TNF-α and TGF-β levels and attenuated the reduction of SOD activity that were induced by bleomycin. Furthermore, excessive collagen deposition was inhibited by the apigenin treatment. Collectively, these results suggest that apigenin may function as a potent anti-inflammatory and anti-fibrotic agent against bleomycin-induced lung fibrosis.

The Effect of Therapeutic Blockades of Dust Particles-Induced Ca²⁺ Signaling and Proinflammatory Cytokine IL-8 in Human Bronchial Epithelial Cells

Bronchial epithelial cells are the first barrier of defense against respiratory pathogens. Dust particles as extracellular stimuli are associated with inflammatory reactions after inhalation. It has been reported that dust particles induce intracellular Ca(2+) signal, which subsequently increases cytokines production such as interleukin- (IL-) 8. However, the study of therapeutic blockades of Ca(2+) signaling induced by dust particles in human bronchial epithelial cells is poorly understood. We investigated how to modulate dust particles-induced Ca(2+) signaling and proinflammatory cytokine IL-8 expression. Bronchial epithelial BEAS-2B cells were exposed to PM10 dust particles and subsequent mediated intracellular Ca(2+) signaling and reactive oxygen species signal. Our results show that exposure to several inhibitors of Ca(2+) pathway attenuated the PM10-induced Ca(2+) response and subsequent IL-8 mRNA expression. PM10-mediated Ca(2+) signal and IL-8 expression were attenuated by several pharmacological blockades such as antioxidants, IP3-PLC blockers, and TRPM2 inhibitors. Our results show that blockades of PLC or TRPM2 reduced both of PM10-mediated Ca(2+) signal and IL-8 expression, suggesting that treatment with these blockades should be considered for potential therapeutic trials in pulmonary epithelium for inflammation caused by environmental events such as seasonal dust storm.

Double-Blind Randomized Trial of Pirfenidone in Chinese Idiopathic Pulmonary Fibrosis Patients

Idiopathic pulmonary fibrosis (IPF) lacks effective treatment. Pirfenidone has been used to treat IPF patients. N-acetylcysteine (NAC) exerts antioxidant and antifibrotic effects on IPF cases.This study is a double-blind, modified placebo-controlled, randomized phase II trial of pirfenidone in Chinese IPF patients. We randomly assigned the enrolled Chinese IPF patients with mild to moderate impairment of pulmonary function to receive either oral pirfenidone (1800 mg per day) and NAC (1800 mg per day) or placebo and NAC (1800 mg per day) for 48 weeks. The primary endpoints were the changes in forced vital capacity (FVC) and walking distance and the lowest SPO2 during the 6-minute walk test (6MWT) at week 48. The key secondary endpoint was the progression-free survival time. This study is registered in ClinicalTrials.gov as number NCT01504334.Eighty-six patients were screened, and 76 cases were enrolled (pirfenidone + NAC: 38; placebo + NAC: 38). The effect of pirfenidone treatment was significant at the 24th week, but this effect did not persist to the 48th week. At the 24th week, the mean decline in both FVC and ΔSPO2 (%) during the 6MWT in the pirfenidone group was lower than that in the control group (-0.08 ± 0.20 L vs -0.22 ± 0.29 L, P = 0.02 and -3.44% ± 4.51% vs -6.29% ± 6.06%, P = 0.03, respectively). However, there was no significant difference between these 2 groups at the 48th week (-0.15 ± 0.25 L vs -0.25 ± 0.28 L, P = 0.11 and -4.25% ± 7.27% vs -5.31% ± 5.49%, P = 0.51, respectively). The pirfenidone treatment group did not achieve the maximal distance difference on the 6MWT at either the 24th or the 48th week. But pirfenidone treatment prolonged the progression-free survival time in the IPF patients (hazard ratio = 1.88, 95% confidence interval: 1.092-3.242, P = 0.02). In the pirfenidone group, the adverse event (AE) rate (52.63%) was higher than that in the control group (26.3%, P = 0.03). Rash was more common in the pirfenidone group (39.5% vs 13.2%, P = 0.02).Compared with placebo combined with high-dose NAC, pirfenidone combined with high-dose NAC prolonged the progression-free survival of Chinese IPF patients with mild to moderate impairment of pulmonary function. (ClinicalTrials.gov number, NCT01504334).

Magnolol reduces bleomycin-induced rodent lung fibrosis

Magnolol, a compound extracted from the Chinese medicinal herb Magnolia officinalis, has been proved to exert multiple pharmacological effects, including anti-oxidant and anti-inflammation activities. In this study, how it influenced bleomycin-induced lung fibrosis of rats was investigated. A single intratracheal instillation of bleomycin (5 mg/Kg, sacrificed 7 and 28 days post bleomycin instillation) caused body weight decrease and lung indices increase. Hodroxyproline content, myeloperoxidase (MPO) activity, tumor necrosis factor-α (TNF-α) and transforming growth factor-β (TGF-β) levels increased in the rat lung tissues after bleomycin administration, while superoxide dismutase (SOD) activity decreased in the rat lung tissues. Collagen were excessively deposited in rat lung tissues after bleomycin treatment. However, oral administration of magnolol (10 mg/Kg, 20 mg/Kg, 30 mg/Kg) apparently and significantly inhibited the fibrotic process. It partly reversed the bleomycin-induced increase of hydroxyproline content, MPO activity, TNF-α and TGF-β levels in the lung tissues, significantly inhibited the bleomycin-induced decrease of SOD activity, Excessive collagen deposition was also inhibited by magnolol administration. In summary, our results suggested that magnolol might be a potent anti-inflammatory and anti-fibrotic agent against bleomycin-induced lung fibrosis.

miR-9-5p suppresses pro-fibrogenic transformation of fibroblasts and prevents organ fibrosis by targeting NOX4 and TGFBR2

Uncontrolled extracellular matrix (ECM) production by fibroblasts in response to injury contributes to fibrotic diseases, including idiopathic pulmonary fibrosis (IPF). Reactive oxygen species (ROS) generation is involved in the pathogenesis of IPF. Transforming growth factor-β1 (TGF-β1) stimulates the production of NADPH oxidase 4 (NOX4)-dependent ROS, promoting lung fibrosis (LF). Dysregulation of microRNAs (miRNAs) has been shown to contribute to LF. To identify miRNAs involved in redox regulation relevant for IPF, we performed arrays in human lung fibroblasts exposed to ROS. miR-9-5p was selected as the best candidate and we demonstrate its inhibitory effect on TGF-β receptor type II (TGFBR2) and NOX4 expression. Increased expression of miR-9-5p abrogates TGF-β1-dependent myofibroblast phenotypic transformation. In the mouse model of bleomycin-induced LF, miR-9-5p dramatically reduces fibrogenesis and inhibition of miR-9-5p and prevents its anti-fibrotic effect both in vitro and in vivo. In lung specimens from patients with IPF, high levels of miR-9-5p are found. In omentum-derived mesothelial cells (MCs) from patients subjected to peritoneal dialysis (PD), miR-9-5p also inhibits mesothelial to myofibroblast transformation. We propose that TGF-β1 induces miR-9-5p expression as a self-limiting homeostatic response.

Bone marrow mesenchymal stem cells protect against bleomycin-induced pulmonary fibrosis in rat by activating Nrf2 signaling

Pulmonary fibrosis is a progressive and lethal disorder. Although the precise mechanisms of pulmonary fibrosis are not fully understood, oxidant/antioxidant may play an important role in many of the processes of inflammation and fibrosis. Keap1-Nrf2-ARE pathway represents one of the most important cellular defense mechanisms against oxidative stress. Mesenchymal stem cells (MSC) are in clinical trials for widespread indications including musculoskeletal, neurological, cardiac and haematological disorders. One emerging concept is that MSCs may have paracrine, rather than a functional, roles in lung injury repair and regeneration. In the present study, we investigated bone marrow mesenchymal stem cells (BMSCs) for the treatment of bleomycin-induced pulmonary fibrosis. Our results showed that BMSCs administration significantly ameliorated the bleomycin mediated histological alterations and blocked collagen deposition with parallel reduction in the hydroxyproline level. The gene expression levels of

NAD(P)H

quinine oxidoreductase 1 (NQO1), gama-glutamylcysteine synthetase (γ-GCS), heme oxygenase-1 (HO-1) and nuclear factor erythroid 2-related factor 2 (Nrf2), attenuated by bleomycin, were increased up to basal levels after BMSCs transplantation. BMSCs significantly increased superoxide dismutase (SOD) activity and inhibited malondialdehyde (MDA) production in the injured lung. The present study provides evidence that BMSCs may be a potential therapeutic reagent for the treatment of lung fibrosis.

Silicon-based quantum dots induce inflammation in human lung cells and disrupt extracellular matrix homeostasis

Quantum dots (QDs) are nanocrystalline semiconductor materials that have been tested for biological applications such as cancer therapy, cellular imaging and drug delivery, despite the serious lack of information of their effects on mammalian cells. The present study aimed to evaluate the potential of Si/SiO2 QDs to induce an inflammatory response in MRC-5 human lung fibroblasts. Cells were exposed to different concentrations of Si/SiO2 QDs (25-200 μg·mL(-1)) for 24, 48, 72 and 96 h. The results obtained showed that uptake of QDs was dependent on biocorona formation and the stability of nanoparticles in various biological media (minimum essential medium without or with 10% fetal bovine serum). The cell membrane damage indicated by the increase in lactate dehydrogenase release after exposure to QDs was dose- and time-dependent. The level of lysosomes increased proportionally with the concentration of QDs, whereas an accumulation of autophagosomes was also observed. Cellular morphology was affected, as shown by the disruption of actin filaments. The enhanced release of nitric oxide and the increase in interleukin-6 and interleukin-8 protein expression suggested that nanoparticles triggered an inflammatory response in MRC-5 cells. QDs decreased the protein expression and enzymatic activity of matrix metalloproteinase (MMP)-2 and MMP-9 and also MMP-1 caseinase activity, whereas the protein levels of MMP-1 and tissue inhibitor of metalloproteinase-1 increased. The present study reveals for the first time that silicon-based QDs are able to generate inflammation in lung cells and cause an imbalance in extracellular matrix turnover through a differential regulation of MMPs and tissue inhibitor of metalloproteinase-1 protein expression.

Improvement in idiopathic nonspecific interstitial pneumonia after smoking cessation

Although cigarette smoking has been recognized as a risk factor for the development of several interstitial lung diseases, the relationship between smoking and nonspecific interstitial pneumonia (NSIP) has not yet been fully elucidated. We here present a case of fibrotic NSIP with mild emphysema in an elderly male with normal pulmonary function, whose symptoms, serum KL-6 level, and high-resolution computed tomography findings of interstitial changes markedly improved without medication following the cessation of smoking. Our case suggests that smoking may be an etiological factor in some patients with NSIP and that early smoking cessation before a clinically detectable decline in pulmonary function may be critical for smokers with idiopathic NSIP.

The sexual dimorphism associated with pulmonary hypertension corresponds to a fibrotic phenotype

Although female predominance in the development of all types of pulmonary hypertension (PH) is well established, many clinical studies have confirmed that females have better prognosis and higher survival rate than males. There is no clear explanation of why sex influences the pathogenesis and progression of PH. Using a rat angioproliferative model of PH, which closely resembles the primary pathological changes observed in humans, we evaluated the role of sex in the development and progression of PH. Female rats had a more pronounced increase in medial thickness in the small pulmonary arteries. However, the infiltration of small pulmonary arteries by inflammatory cells was found only in male rats, and this corresponded to increased myeloperoxidase activity and abundant adventitial and medial fibrosis that were not present in female rats. Although the level of right ventricle (RV) peak systolic pressure was similar in both groups, the survival rate in male rats was significantly lower. Moreover, male rats presented with a more pronounced increase in RV thickness that correlated with diffuse RV fibrosis and significantly impaired right cardiac function. The reduction in fibrosis in female rats correlated with increased expression of caveolin-1 and reduced endothelial nitric oxide synthase-derived superoxide. We conclude that, in the pathogenesis of PH, female sex is associated with greater remodeling of the pulmonary arteries but greater survival. Conversely, in males, the development of pulmonary and cardiac fibrosis leads to early and severe RV failure, and this may be an important reason for the lower survival rate among males.

Selenium and exposure to fibrogenic mineral dust: a mini-review

Individuals exposed to fibrogenic mineral dust may exhibit an impaired antioxidant system and produce high levels of reactive oxygen and nitrogen species through immune cells, contributing to the perturbation of immune cell function, inflammation, fibrosis and lung cancer. The lung diseases which are caused by inhalation of fibrogenic mineral dust, known as pneumoconioses, develop progressively and irreversibly over decades. At the moment there is no known cure. The trace element selenium has potent antioxidant and anti-inflammatory properties mediated mainly through selenoproteins. Research has demonstrated that selenium has the ability to protect against cardiovascular diseases; to kill cancer cells in vitro and reduce cancer incidence; and to immunomodulate various cellular signaling pathways. For these reasons, selenium has been proposed as a promising therapeutic agent in oxidative stress associated pathology that in theory would be beneficial for the prevention or treatment of pneumoconioses such as silicosis, asbestosis, and coal worker's pneumoconiosis. However, studies regarding selenium and occupational lung diseases are rare. The purpose of this study is to conduct a mini-review regarding the relationship between selenium and exposure to fibrogenic mineral dust with emphasis on epidemiological studies. We carried out a systematic literature search of English published studies on selenium and exposure to fibrogenic mineral dust. We found four epidemiological studies. Reviewed studies show that selenium is lower in individuals exposed to fibrogenic mineral dust. However, three out of the four reviewed studies could not confirm cause-and-effect relationships between low selenium status and exposure to fibrogenic mineral dust. This mini-review underscores the need for large follow-up and mechanistic studies for selenium to further elucidate its therapeutic effects.

Polyhexamethylene guanidine phosphate aerosol particles induce pulmonary inflammatory and fibrotic responses

Polyhexamethylene guanidine (PHMG) phosphate was used as a disinfectant for the prevention of microorganism growth in humidifiers, without recognizing that a change of exposure route might cause significant health effects. Epidemiological studies reported that the use of humidifier disinfectant containing PHMG-phosphate can provoke pulmonary fibrosis. However, the pulmonary toxicity of PHMG-phosphate aerosol particles is unknown yet. This study aimed to elucidate the toxicological relationship between PHMG-phosphate aerosol particles and pulmonary fibrosis. An in vivo nose-only exposure system and an in vitro air-liquid interface (ALI) co-culture model were applied to confirm whether PHMG-phosphate induces inflammatory and fibrotic responses in the respiratory tract. Seven-week-old male Sprague-Dawley rats were exposed to PHMG-phosphate aerosol particles for 3 weeks and recovered for 3 weeks in a nose-only exposure chamber. In addition, three human lung cells (Calu-3, differentiated THP-1 and HMC-1 cells) were cultured at ALI condition for 12 days and were treated with PHMG-phosphate at set concentrations and times. The reactive oxygen species (ROS) generation, airway barrier injuries and inflammatory and fibrotic responses were evaluated in vivo and in vitro. The rats exposed to PHMG-phosphate aerosol particles in nanometer size showed pulmonary inflammation and fibrosis including inflammatory cytokines and fibronectin mRNA increase, as well as histopathological changes. In addition, PHMG-phosphate triggered the ROS generation, airway barrier injuries and inflammatory responses in a bronchial ALI co-culture model. Those results demonstrated that PHMG-phosphate aerosol particles cause pulmonary inflammatory and fibrotic responses. All features of fibrogenesis by PHMG-phosphate aerosol particles closely resembled the pathology of fibrosis that was reported in epidemiological studies. Finally, we expected that PHMG-phosphate infiltrated into the lungs in the form of aerosol particles would induce an airway barrier injury via ROS, release fibrotic inflammatory cytokines, and trigger a wound-healing response, leading to pulmonary fibrosis. A simultaneous state of tissue destruction and inflammation caused by PHMG-phosphate had whipped up a "perfect storm" in the respiratory tract.

Tanshinone IIA attenuates bleomycin-induced pulmonary fibrosis in rats

Idiopathic pulmonary fibrosis is a chronic and progressive fibrotic lung disorder with unknown etiology and a high mortality rate. Tanshinone IIA (Tan IIA) is a lipophilic diterpene extracted from the Chinese herb Salvia miltiorrhiza Bunge with diverse biological functions. The present study was conducted to evaluate the effects of Tan IIA on bleomycin (BLM)-induced pulmonary fibrosis in rats. Rats received an intraperitoneal injection of Tan IIA and normal rats were used as controls. Severe pulmonary edema, inflammation and fibrosis were observed in the BLM-treated rats and the counts of total cells, neutrophils and lymphocytes were significantly increased in the bronchoalveolar lavage fluids of those rats. These pathological changes were markedly attenuated by subsequent treatment with Tan IIA. In addition, BLM-induced increased expression of tumor necrosis factor-α, interleukin (IL)-1β, IL-6, cyclooxygenase-2, prostaglandin E2, malondialdehyde, inducible nitric oxide synthase and nitric oxide in rats, which was also suppressed by Tan IIA injection. The present findings suggest therapeutic potential of Tan IIA for pulmonary fibrosis.

Dual effect of oxidative stress on leukemia cancer induction and treatment

Oxidative stress (OS) has been characterized by an imbalance between the production of reactive oxygen species (ROS) and a biological system's ability to repair oxidative damage or to neutralize the reactive intermediates including peroxides and free radicals. High ROS production has been associated with significant decrease in antioxidant defense mechanisms leading to protein, lipid and DNA damage and subsequent disruption of cellular functions. In humans, OS has been reported to play a role in the pathogenesis of neurodegenerative diseases such as Alzheimer's disease, Huntington's disease, Lou Gehrig's disease, multiple sclerosis and Parkinson's disease, as well as atherosclerosis, autism, cancer, heart failure, and myocardial infarction. Although OS has been linked to the etiology and development of chronic diseases, many chemotherapeutic drugs have been shown to exert their biologic activity through induction of OS in affected cells. This review highlights the controversial role of OS in the development and progression of leukemia cancer and the therapeutic application of increased OS and antioxidant approaches to the treatment of leukemia patients.

Naja naja atra venom ameliorates pulmonary fibrosis by inhibiting inflammatory response and oxidative stress

BACKGROUND

Naja naja atra venom (NNAV) displays diverse pharmacological actions including analgesia, anti-inflammation and immune regulation.In this study, we investigated the effects of NNAV on pulmonary fibrosis and its mechanisms of action.

METHODS

To determine if Naja naja atra venom (NNAV) can produce beneficial effects on pulmonary fibrosis, two marine models of pulmonary fibrosis were produced with bleomycin (BLM) and lipopolysaccharide (LPS). NNAV (30, 90, 270 μg/kg) was orally administered once a day started five days before BLM and LPS until to the end of experiment. The effects of NNAV treatment on pulmonary injury were evaluated with arterial blood gas analysis, hydroxyproline (HYP) content assessment and HE/Masson staining. The effects of NNAV treatment on inflammatory related cytokines, fibrosis related TGF-β/Smad signaling pathway and oxidative stress were examined.

RESULTS

The results showed that NNAV improved the lung gas-exchange function and attenuated the fibrotic lesions in lung. NNAV decreased IL-1β and TNF-α levels in serum in both pulmonary fibrosis models. NNAV inhibited the activation of NF-κB in LPS-induced and TGF-β/Smad pathway in BLM-induced pulmonary fibrosis. Additionally, NNAV also increased the levels of SOD and GSH and reduced the levels of MDA in BLM-induced pulmonary fibrosis model.

CONCLUSIONS

The present study indicates that NNAV attenuates LPS- and BLM-induced lung fibrosis. Its mechanisms of action are associated with inhibiting inflammatory response and oxidative stress. The study suggests that NNAV might be a potential therapeutic drug for treatment of pulmonary fibrosis.

Myofibroblast differentiation: main features, biomedical relevance, and the role of reactive oxygen species

SIGNIFICANCE

Myofibroblasts are prototypical fibrotic cells, which are involved in a number of more or less pathological conditions, from foreign body reactions to scarring, from liver, kidney, or lung fibrosis to neoplastic phenomena. The differentiation of precursor cells (not only of fibroblastic nature) is characterized by a complex interplay between soluble factors (growth factors such as transforming growth factor β1, reactive oxygen species [ROS]) and material properties (matrix stiffness).

RECENT ADVANCES

The last 15 years have seen very significant advances in the identification of appropriate differentiation markers, in the understanding of the differentiation mechanism, and above all, the involvement of ROS as causative and persistence factors.

CRITICAL ISSUES

The specific mechanisms of action of ROS remain largely unknown, although evidence suggests that both intracellular and extracellular phenomena play a role.

FUTURE DIRECTIONS

Approaches based on antioxidant (ROS-scavenging) principles and on the potentiation of nitric oxide signaling hold much promise in view of a pharmacological therapy of fibrotic phenomena. However, how to make the active principles available at the target sites is yet a largely neglected issue.

Nitric oxide exerts protective effects against bleomycin-induced pulmonary fibrosis in mice

BACKGROUND

Increased expression of nitric oxide synthase (NOS) and an increase in plasma nitrite plus nitrate (NOx) have been reported in patients with pulmonary fibrosis, suggesting that nitric oxide (NO) plays an important role in its development. However, the roles of the entire NO and NOS system in the pathogenesis of pulmonary fibrosis still remain to be fully elucidated. The aim of the present study is to clarify the roles of NO and the NOS system in pulmonary fibrosis by using the mice lacking all three NOS isoforms.

METHODS

Wild-type, single NOS knockout and triple NOS knockout (n/i/eNOS-/-) mice were administered bleomycin (BLM) intraperitoneally at a dose of 8.0 mg/kg/day for 10 consecutive days. Two weeks after the end of the procedure, the fibrotic and inflammatory changes of the lung were evaluated. In addition, we evaluated the effects of long-term treatment with isosorbide dinitrate, a NO donor, on the n/i/eNOS-/- mice with BLM-induced pulmonary fibrosis.

RESULTS

The histopathological findings, collagen content and the total cell number in bronchoalveolar lavage fluid were the most severe/highest in the n/i/eNOS-/- mice. Long-term treatment with the supplemental NO donor in n/i/eNOS-/- mice significantly prevented the progression of the histopathological findings and the increase of the collagen content in the lungs.

CONCLUSIONS

These results provide the first direct evidence that a lack of all three NOS isoforms led to a deterioration of pulmonary fibrosis in a BLM-treated murine model. We speculate that the entire endogenous NO and NOS system plays an important protective role in the pathogenesis of pulmonary fibrosis.

The discovery and development of new potential antioxidant agents for the treatment of neurodegenerative diseases

INTRODUCTION

Several neurodegenerative disorders (NDs) including Alzheimer's and Huntington's diseases have had associations with the oxidative process and free radical damage. Consequently, in past decades, several natural and synthetic antioxidants have been assessed as therapeutic agents but have shown limitations in bioavailability, metabolic susceptibility and permeability to the blood brain barrier. Given these issues, medicinal chemists are hard at work to modify/improve the chemical structures of these antioxidants, thereby improving their efficacy.

AREAS COVERED

In this review, the authors critically analyze several biological mechanisms involved in the generation of free radicals. Additionally, they analyze free radicals' role in the generation of oxidative stress and in the progression of many NDs. Further, the authors review a collection of natural and synthetic antioxidants, their role as free radical scavengers along with their mechanisms of action and their potential for preventing neurodegenerative diseases.

EXPERT OPINION

So far, preclinical studies on several antioxidants have shown promise for treating NDs, despite their limitations. The authors do highlight the lack of the adequate animal models for preclinical assessment and this does hinder further progression into clinical trials. Further studies are necessary to fully investigate the potential of these antioxidants as ND therapeutic options.

Matrix biology of idiopathic pulmonary fibrosis: a workshop report of the national heart, lung, and blood institute

A hallmark of idiopathic pulmonary fibrosis (IPF) is excessive and disordered deposition of extracellular matrix. Although the lung extracellular matrix normally plays an essential role in development and maintenance of lung tissue through reciprocal interactions with resident cells, the disordered matrix in the diseased lung is increasingly recognized as an active and important contributor to IPF pathogenesis. This working group summary from a recently conducted National Heart, Lung, and Blood Institute strategic planning workshop for IPF research highlights recent advances, challenges, and opportunities in the study of matrix biology in IPF. Particular attention is given to the composition and mechanical properties of the matrix in normal and diseased lungs, and the biochemical and biomechanical influences exerted by pathological matrix. Recently developed model systems are also summarized as key tools for advancing our understanding of matrix biology in IPF. Emerging approaches to therapeutically target the matrix in preclinical and clinical settings are discussed, as are important concepts, such as alterations of the matrix with aging and the potential for the resolution of fibrosis. Specific recommendations for future studies in matrix biology of IPF are also proposed.

Reversal of persistent fibrosis in aging by targeting Nox4-Nrf2 redox imbalance

The incidence and prevalence of pathological fibrosis increase with advancing age, although mechanisms for this association are unclear. We assessed the capacity for repair of lung injury in young (2 months) and aged (18 months) mice. Whereas the severity of fibrosis was not different between these groups, aged mice demonstrated an impaired capacity for fibrosis resolution. Persistent fibrosis in lungs of aged mice was characterized by the accumulation of senescent and apoptosis-resistant myofibroblasts. These cellular phenotypes were sustained by alterations in cellular redox homeostasis resulting from elevated expression of the reactive oxygen species-generating enzyme Nox4 [NADPH (reduced form of nicotinamide adenine dinucleotide phosphate) oxidase-4] and an impaired capacity to induce the Nrf2 (NFE2-related factor 2) antioxidant response. Lung tissues from human subjects with idiopathic pulmonary fibrosis (IPF), a progressive and fatal lung disease, also demonstrated this Nox4-Nrf2 imbalance. Nox4 mediated senescence and apoptosis resistance in IPF fibroblasts. Genetic and pharmacological targeting of Nox4 in aged mice with established fibrosis attenuated the senescent, antiapoptotic myofibroblast phenotype and led to a reversal of persistent fibrosis. These studies suggest that loss of cellular redox homeostasis promotes profibrotic myofibroblast phenotypes that result in persistent fibrosis associated with aging. Our studies suggest that restoration of Nox4-Nrf2 redox balance in myofibroblasts may be a therapeutic strategy in age-associated fibrotic disorders, potentially able to resolve persistent fibrosis or even reverse its progression.

Inhibitory effects of hydrogen sulphide on pulmonary fibrosis in smoking rats via attenuation of oxidative stress and inflammation

Accumulating evidence has demonstrated that hydrogen sulphide (H2 S) is involved in the pathogenesis of various respiratory diseases. In the present study, we established a rat model of passive smoking and investigated whether or not H2 S has protective effects against pulmonary fibrosis induced by chronic cigarette smoke exposure. Rat lung tissues were stained with haematoxylin-eosin and Masson's trichrome. The expression of type I collagen was detected by immunohistochemistry. Oxidative stress was evaluated by detecting serum levels of malondialdehyde, superoxide dismutase and glutathione peroxidase and measuring reactive oxygen species generation in lung tissue. Inflammation was assessed by measuring serum levels of inflammatory cytokines, including high-sensitivity C-reactive protein, tumour necrosis factor-α, interleukin (IL)-1β and IL-6. The protein expression of Nrf2, NF-κB and phosphorylated mitogen-activated protein kinases (MAPKs) in the pulmonary tissue was determined by Western blotting. Our findings indicated that administration of NaHS (a donor of H2 S) could protect against pulmonary fibrosis in the smoking rats. H2 S was found to induce the nuclear accumulation of Nrf2 in lung tissue and consequently up-regulate the expression of antioxidant genes HO-1 and Trx-1 in the smoking rats. Moreover, H2 S could also reduce cigarette smoking-induced inflammation by inhibiting the phosphorylation of ERK 1/2, JNK and p38 MAPKs and negatively regulating NF-κB activation. In conclusion, our study suggests that H2 S has protective effects against pulmonary fibrosis in the smoking rats by attenuating oxidative stress and inflammation.

The treatment of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive and invariably fatal disease with a median survival of less than three years from diagnosis. The last decade has seen an exponential increase in clinical trial activity in IPF and this in turn has led to important developments in the treatment of this terrible disease. Previous therapeutic approaches based around regimens including corticosteroids and azathioprine have, when tested in randomized clinical trials, been shown to be harmful in IPF. By contrast, compounds with anti-fibrotic actions have been shown to be beneficial. Subsequently, the novel anti-fibrotic agent pirfenidone has, in many parts of the world, become the first treatment ever to be licensed for use in IPF. This exciting development, coupled with ongoing clinical trials of a range of other novel compounds, is bringing hope to patients and their clinicians and raises the prospect that, in the future, it may become possible to successfully arrest the development of progressive scarring in IPF.

Chronic alcohol ingestion and predisposition to lung "cirrhosis"

BACKGROUND

Although liver is the organ most often associated with the damaging effects of chronic alcohol abuse, other organs may also be affected. In the past decade, data emerged linking chronic alcohol intake to lung dysfunction. However, the mechanisms by which alcohol affects the lung remain incompletely elucidated.

METHODS

In this issue, Sueblinvong and colleagues explore the effect of chronic alcohol intake in the well-known rodent model of bleomycin-induced lung injury. This represents a review of their article and a commentary on its findings in relation to current knowledge in the field.

RESULTS

The investigators found that chronic alcohol intake increased lung fibrosis in the bleomycin-model of lung injury. This effect was related to increased production of transforming growth factor β (TGFβ) and expression of α-smooth muscle actin. Diet supplementation with S-adenosylmethionine greatly reduced the effect. These data strengthen published reports linking chronic alcohol intake with TGFβ overproduction and lung disrepair after injury, while implicating oxidant stress as a critical mediator of these effects.

CONCLUSIONS

A review of Sueblinvong and colleagues' article and the literature strongly suggests that the lung is a target for alcohol, and that chronic alcohol intake may predispose the lung to disrepair after injury. The overexpression of pro-fibrotic growth factors and pro-inflammatory cytokines, and the generation of oxidant stress may lead to lung cellular dysfunction, aberrant tissue remodeling, and loss of lung function. These events may represent targets for intervention, but translational studies evaluating their role in humans are desperately needed.