N-acetylcysteine downregulation of lysyl oxidase activity alleviating bleomycin-induced pulmonary fibrosis in rats

Efficacy of N-acetylcysteine plus pirfenidone in the treatment of idiopathic pulmonary fibrosis: a systematic review and meta-analysis

BACKGROUND

Numerous studies have demonstrated the potential of pirfenidone to enhance the prognosis of patients afflicted with idiopathic pulmonary fibrosis (IPF). Although N-acetylcysteine (NAC) is utilized as an antioxidant in IPF treatment, the combination of NAC and pirfenidone has produced inconsistent outcomes in certain studies. To assess the clinical effectiveness and safety of NAC plus pirfenidone (designated as the treatment group) versus pirfenidone monotherapy (designated as the control group), we conducted a systematic review and meta-analysis of randomized controlled trials (RCTs).

METHODS

RCTs of NAC plus pirfenidone were reviewed searching from databases and networks of unpublished and published studies in any language. Using pair-wise meta-analysis, changes in pulmonary function test (PFT) parameters and safety were evaluated.

RESULTS

Two independent reviewers selected and obtained data from 5 RCTs (n = 398), comprising 1 study from Japan, 1 from Europe, and 3 from China. NAS plus pirfenidone as compared to pirfenidone monotherapy for IPF may not reduce the incidence of skin effects(RR 1.26 [95%CI 0.64 to 2.45]) and mortality(RR 0.35 [95%CI 0.07 to 1.68])(both moderate certainty). NAS plus pirfenidone as compared to pirfenidone monotherapy for IPF may not reduce the incidence of at least one side effects(RR 1.00 [95%CI 0.84 to 1.19]; low certainty),severe side effects(RR 0.67 [95%CI 0.30 to 1.47]; low certainty) and gastrointestinal effects(RR 0.67 [95%CI 0.41 to 1.09]; low certainty) with possibly no effect in Δ%DLco(SMD -0.17 [95%CI -0.15 to 0.48]; low certainty). Meanwhile, the effect of NAS plus pirfenidone as compared to pirfenidone monotherapy on ΔFVC(SMD 0.18 [95%CI -0.68 to 1.05]), Δ%FVC(SMD -2.62 [95%CI -5.82 to 0.59]) and Δ6MWT(SMD -0.35 [95%CI -0.98 to 0.28]) is uncertain(extremely low certainty).

CONCLUSION

Moderate certainty evidence suggests that NAS plus pirfenidone, compared to pirfenidone monotherapy for IPF, does not reduce the incidence of skin effects and mortality.

Advances in the Use of N-Acetylcysteine in Chronic Respiratory Diseases

N-acetylcysteine (NAC) is widely used because of its mucolytic effects, taking part in the therapeutic protocols of cystic fibrosis. NAC is also administered as an antidote in acetaminophen (paracetamol) overdosing. Thanks to its wide antioxidative and anti-inflammatory effects, NAC may also be of benefit in other chronic inflammatory and fibrotizing respiratory diseases, such as chronic obstructive pulmonary disease, bronchial asthma, idiopathic lung fibrosis, or lung silicosis. In addition, NAC exerts low toxicity and rare adverse effects even in combination with other treatments, and it is cheap and easily accessible. This article brings a review of information on the mechanisms of inflammation and oxidative stress in selected chronic respiratory diseases and discusses the use of NAC in these disorders.

Involvement of Cu-containing amine oxidases in the development of lung pathology in ovalbumin-induced bronchial asthma in guinea pigs

Bronchial asthma is developed as an immune response to allergen challenges accompanied by inflammation and fibrosis implicated in airway remodeling. To reveal the causative implication of Cu-containing amino oxidases semicarbazide-sensitive amine oxidase (SSAO), DAO and lysyl oxidase (LOX) in BA development we used their irreversible inhibitor semicarbazide and guinea pig model of BA induced by ovalbumin. Semicarbazide was introduced to asthmatic animals via drink or inhalation. At the 16th week after disease induction, the increase in the activity of pro-inflammatory SSAO and DAO in plasma (1.6 and 2 times, respectively) was observed. The introduction of semicarbazide to asthmatic animals via drink or inhalation significantly decreased activities of these enzymes compared to the untreated asthmatic animals. A considerable­ increase in IL-13 content and LOX activity in the lung tissue of asthmatic animals were observed that evidenced airway inflammation and pulmonary fibrosis development. The uptake of semicarbazide by guinea pigs with bronchial asthma led to normalization of LOX activity. Histological studies confirmed that semicarbazide attenuated morphopathological changes in the lungs of asthmatic animals. Thus, the data obtained indicate the direct participation of the studied enzymes in the progression of pathological processes in atopic bronchial asthma as well as the potential use of semicarbazide as a drug in complex anti-asthmatic therapy. Keywords: atopic bronchial asthma, histaminase/diamine oxidase, IL-13, lysyl oxidase, nitric oxide, semicarbazide, semicarbazide sensitive amine oxidase

Exploring Idiopathic Pulmonary Fibrosis Biomarker by Simultaneous Two-Photon Fluorescence Imaging of Cysteine and Peroxynitrite

Idiopathic pulmonary fibrosis (IPF) has been characterized as a chronic inflammatory disease that leads to irreversible damage to pulmonary function. However, there is no specific IPF biomarker that can be used to distinguish IPF and not pneumonia. Endoplasmic reticulum (ER) stress is prominent in IPF. To search for a specific biomarker of IPF, we developed two ER-targeting two-photon (TP) fluorescent probes, TP^ER-ONOO and TP^ER-Cys, for peroxynitrite (ONOO^-) and cysteine (Cys) imaging, respectively. A significant increase in Cys levels in the lungs was discovered only in mice with IPF, which implied that Cys might be an IPF biomarker candidate. Furthermore, we uncovered the mechanism of glutathione (GSH) deficiency in IPF, which was not due to Cys shortage but instead was attributable to impaired glutamate cysteine ligase and glutathione synthetase activities via ONOO^--induced post-transcriptional modification. This work has potential to provide a new method for IPF early diagnosis and drug efficacy evaluation.

Clinical efficacy of Chinese herbs for supplementing qi and activating blood circulation combined with N-acetylcysteine in the treatment of idiopathic pulmonary fibrosis: A systematic review and network meta-analysis

BACKGROUND

Chinese herbs for supplementing qi and activating blood circulation (CH) combined with N-acetylcysteine (NAC) is widely used for idiopathic pulmonary fibrosis (IPF) in China, but there is a lack of literature to evaluate its efficacy and clinical value.

PURPOSE

This study compared CH + NAC with other treatments by network meta-analysis to clarify its clinical value.

METHODS

Cochrane Library, PubMed, Embase, Web of Science, China National Knowledge Infrastructure, WanFang Data, VIP Database, and China Biology Medicine were searched. Outcomes included lung function (DLCO (%), VC (%), FVC (%), FVC (L)), 6-min walking distance (6MWD), score of St George's respiratory questionnaire (SGRQ), blood gas analysis (PaO2, PaCO2). The data were analyzed by Review Manager 5.4, Stata 12.0 and ADDIS 1.16.5.

RESULTS

23 studies including 1390 patients (702 in intervention group and 688 in control group) were collected to compare 8 outcome indicators among different treatments involving CH, CH+NAC, CH+PFD, NAC, PFD and PFD+NAC on IPF. Network meta-analysis showed that CH was better than NAC in terms of DLCO (%) (MD = 5.14, 95%CI: 1.01 to 8.68) and 6MWD (MD = 49.17, 95%CI: 25.97 to 71.36) as well as PFD + NAC was better than NAC in terms of FVC (L) (MD = -0.56, 95%CI: -0.83 to -0.31). In rankings results, CH + NAC is the best in terms of FVC (%), SGRQ, PaO2 and PaCO2; CH is the best in terms of DLCO (%), VC (%) and 6MWD; CH + PFD is the best in terms of FVC (L).

CONCLUSION

CH related treatments may have advantages in the treatment of IPF and CH + NAC may have clinical application value. However, limited by the quality and quantity of researches included, more rational and scientific randomized controlled trials containing large sample sizes need to be conducted to further verify our conclusions.

Efficacy of Qingfei oral liquid for idiopathic pulmonary fibrosis in rats and related network pharmacology study

To investigate the therapeutic effect and mechanism of Qingfei oral liquid in idiopathic pulmonary fibrosis. Seventy-two male SD rats were divided into control group, model group, pirofenidone group and Qingfei group with 18 animals in each group. The idiopathic pulmonary fibrosis was induced in last three groups by intratracheal injection of bleomycin; pirofenidone group was given oral administration of pirofenidone b.i.d for 21 d, and Qingfei group was given Qingfei oral liquid 3.6 mL/kg q.d for Lung tissues were obtained for HE staining, Masson staining and transforming growth factor (TGF)-β immunohistochemical staining. Superoxide dismutase (SOD), malondialdehyde (MDA) and glutathione (GSH) were detected in tissue homogenates. The BATMAN-TCM database was used to retrieve the chemical components and their corresponding targets of Qingfei oral solution by network pharmacology method, and then the component-target-disease network diagram was constructed. Finally, the pathway enrichment analysis was carried out to explore the molecular mechanism of Qingfei oral liquid against idiopathic fibrosis. Histopathology results showed that Qingfei oral liquid had a similar relieving effect on pulmonary fibrosis as the positive drug pirfenidone; TGF-β secretion had a significant reduction in lung tissues of Qingfei group; and Qingfei oral liquid had better regulatory effect on SOD, MDA and GSH than pirfenidone. The results of component-target-disease network and pathway enrichment analysis showed that the related molecular pathways were concentrated in inflammation, extracellular matrix and cytokines. Qingfei oral liquid has a good therapeutic effect on idiopathic pulmonary fibrosis in rats via regulation of inflammation, extracellular matrix and cytokines.

Targeting Oxidative Stress as a Therapeutic Approach for Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic interstitial lung disease characterized by an abnormal reepithelialisation, an excessive tissue remodelling and a progressive fibrosis within the alveolar wall that are not due to infection or cancer. Oxidative stress has been proposed as a key molecular process in pulmonary fibrosis development and different components of the redox system are altered in the cellular actors participating in lung fibrosis. To this respect, several activators of the antioxidant machinery and inhibitors of the oxidant species and pathways have been assayed in preclinical in vitro and in vivo models and in different clinical trials. This review discusses the role of oxidative stress in the development and progression of IPF and its underlying mechanisms as well as the evidence of oxidative stress in human IPF. Finally, we analyze the mechanism of action, the efficacy and the current status of different drugs developed to inhibit the oxidative stress as anti-fibrotic therapy in IPF.

N-acetylcysteine inhibits thrombosis in a murine model of myeloproliferative neoplasm

Thrombosis is a major cause of mortality in patients with myeloproliferative neoplasms (MPNs), though there is currently little to offer patients with MPN beyond aspirin and cytoreductive therapies such as hydroxyurea for primary prevention. Thrombogenesis in MPN involves multiple cellular mechanisms, including platelet activation and neutrophil-extracellular trap formation; therefore, an antithrombotic agent that targets one or more of these processes would be of therapeutic benefit in MPN. Here, we treated the JAK2V617F knockin mouse model of polycythemia vera with N-acetylcysteine (NAC), a sulfhydryl-containing compound with broad effects on glutathione replenishment, free radical scavenging, and reducing disulfide bonds, to investigate its antithrombotic effects in the context of MPN. Strikingly, NAC treatment extended the lifespan of JAK2V617F mice without impacting blood counts or splenomegaly. Using an acute pulmonary thrombosis model in vivo, we found that NAC reduced thrombus formation to a similar extent as the irreversible platelet inhibitor aspirin. In vitro analysis of platelet activation revealed that NAC reduced thrombin-induced platelet-leukocyte aggregate formation in JAK2V617F mice. Furthermore, NAC reduced neutrophil extracellular trap formation in primary human neutrophils from patients with MPN as well as healthy controls. These results provide evidence that N-acetylcysteine inhibits thrombosis in JAK2V617F mice and provide a pre-clinical rationale for investigating NAC as a therapeutic to reduce thrombotic risk in MPN.

N-acetylcysteine maintains penile length and erectile function in bilateral cavernous nerve crush rat model by reducing penile fibrosis

Penile length shortening and erectile dysfunction are common complications after radical prostatectomy. Various methods have been used to maintain erectile function, but less attention has been paid to preserving penis length. N-acetylcysteine (NAC) has the effect of antioxidation and antifibrotic, which may be beneficial to improve those postoperative complications. This study investigated the effect of NAC on maintaining the penile length and the erectile function after bilateral cavernous nerve crush (BCNC) and its underlying mechanism. Twenty-four male rats were randomly divided into three groups: control group, BCNC group, and BCNC + NAC group. NAC or equal volume of saline was daily administrated by intragastric gavage for 4 weeks. The initial and end penile lengths were measured. Intracavernosal pressure/mean arterial pressure (ICP/MAP) ratio was calculated to assess erectile function. Hematoxylin–eosin staining, Masson's trichrome staining, immunohistochemistry, and Western blot were performed to explore cellular and molecular changes of the penis. Compared to the BCNC group, the penile length, ICP/MAP ratio and smooth muscle/collagen ratio in the BCNC + NAC group were improved significantly (all P < 0.05), and the expressions of endothelial nitric oxide synthase, α-smooth muscle actin, glutathione, and glutathione peroxidase 1 were significantly increased after NAC treated (all P < 0.05), along with the decreased expressions of hypoxia-inducible factor-1α, transforming growth factor-β1, collagen I, collagen III, collagen IV, malonaldehyde, and lysine oxidase (all P < 0.05). This study demonstrated that NAC could maintain penile length and partly improve erectile function. Possible mechanism is directly and/or indirectly related to antihypoxic and antifibrosis.

Lysyl Oxidase (LOX) Family Members: Rationale and Their Potential as Therapeutic Targets for Liver Fibrosis

The cross-linking of structural extracellular matrix (ECM) components, especially fibrillar collagens and elastin, is strongly implicated in fibrosis progression and resistance to fibrosis reversal. Lysyl oxidase family members (LOX and LOXL1 [lysyl oxidase-like 1], LOXL2 [lysyl oxidase-like 2], LOXL3 [lysyl oxidase-like 3], and LOXL4 [lysyl oxidase like 4]) are extracellular copper-dependent enzymes that play a key role in ECM cross-linking, but have also other intracellular functions relevant to fibrosis and carcinogenesis. Although the expression of most LOX family members is elevated in experimental liver fibrosis of diverse etiologies, their individual contribution to fibrosis is incompletely understood. Inhibition of the LOX family as a whole and of LOX, LOXL1, and LOXL2 specifically has been shown to suppress fibrosis progression and accelerate its reversal in rodent models of cardiac, renal, pulmonary, and liver fibrosis. Recent disappointing clinical trials with a monoclonal antibody against LOXL2 (simtuzumab) in patients with pulmonary and liver fibrosis dampened enthusiasm for LOX family member inhibition. However, this unexpected negative outcome may be related to the inefficient antibody, rather than to LOXL2, not qualifying as a relevant antifibrotic target. Moreover, LOX family members other than LOXL2 may prove to be attractive therapeutic targets. In this review, we summarize the structural hallmarks, expression patterns, covalent cross-linking activities, and modes of regulation of LOX family members and discuss the clinical potential of their inhibition to treat fibrosis in general and liver fibrosis in particular.

The extracellular matrix and mechanotransduction in pulmonary fibrosis

Pulmonary fibrosis is characterised by excessive scarring in the lung which leads to compromised lung function, serious breathing problems and in some diseases, death. It includes several lung disorders with idiopathic pulmonary fibrosis (IPF) the most common and most severe. Pulmonary fibrosis is considered to be perpetuated by aberrant wound healing which leads to fibroblast accumulation, differentiation and activation, and deposition of excessive amounts of extracellular matrix (ECM) components, in particular, collagen. Recent studies have identified the importance of changes in the composition and structure of lung ECM during the development of pulmonary fibrosis and the interaction between ECM and lung cells. There is strong evidence that increased matrix stiffness induces changes in cell function including proliferation, migration, differentiation and activation. Understanding how changes in the ECM microenvironment influence cell behaviour during fibrogenesis, and the mechanisms regulating these changes, will provide insight for developing new treatments.

Downregulation of lysyl oxidase in venous malformations: Association with vascular destabilization and sclerotherapy

Venous malformations (VM) are localized defects in vascular morphogenesis manifested by dilated venous channels with reduced perivascular cell coverage. As a vital enzyme for extracellular matrix (ECM) deposition, lysyl oxidase (LOX) plays important roles in vascular development and diseases. However, the expression and significance of LOX are unknown in VM. Herein, 22 VM specimens and eight samples of normal skin tissues were evaluated immunohistochemically for the expression of LOX, α-smooth muscle cell actin (α-SMA) and transforming growth factor-β (TGF-β). In vitro studies on human umbilical vein endothelial cells (HUVEC) were employed for determining potential mechanisms. Our results showed that LOX expression was significantly reduced in VM compared with normal skin tissues, in parallel with attenuated perivascular α-SMA⁺ cell coverage and TGF-β downregulation in VM. Further correlation analysis indicated that LOX expression was positively correlated with perivascular α-SMA⁺ cell coverage and TGF-β expression in VM. Moreover, marked elevation of LOX, TGF-β and α-SMA was observed in bleomycin-treated VM samples. Furthermore, our in vitro data demonstrated that both recombinant TGF-β and bleomycin induced obvious increase of LOX expression and activity and a concomitant increase in ECM components in HUVEC, which could be reversed by LOX inhibition. To our best knowledge, this study revealed for the first time the downregulation of LOX in VM and its correlation with vascular destabilization and TGF-β-induced endothelial ECM deposition. Moreover, our results highlighted that LOX may be implicated in the sclerotherapy of VM and holds promise as a therapeutic target.

LOX/LOXL in pulmonary fibrosis: potential therapeutic targets

Lysyl oxidase (LOX) and lysyl oxidase-like proteins (LOXL), a family of extracellular matrix (ECM) crosslinking enzymes that have been recognised as playing an important role in fibrogenesis for more than 40 years, are logical targets for antifibrotic treatments. Pulmonary fibrosis, especially idiopathic pulmonary fibrosis (IPF), is a progressive and lethal disease characterised by excessive deposition of ECM in the lung parenchyma. In this review, we discuss the current clinical approaches for IPF and review members of LOX family-LOX, LOXL1, LOXL2, LOXL3 and LOXL4 in IPF patients and in animal models of bleomycin-induced pulmonary fibrosis. Although these findings are controversial and require further validation, LOX/LOXL1/LOXL2 as potential therapeutic targets for IPF deserve continued attention. So far to our knowledge, LOXL3 or LOXL4 has not clearly shown specific therapeutic potential.

Ethyl Pyruvate Improves Pulmonary Function in Mice with Bleomycin-induced Lung Injury as Monitored with Hyperpolarized 129Xe MR Imaging

Purpose:

High Mobility Group Box1 (HMGB1), which is one of the damage-associated molecular pattern molecules relating to various inflammatory diseases, has gained interest as a therapeutic target because of its involvement in wound healing processes. In the present study, we investigated HMGB1 as a potential therapeutic target in a model of lung fibrosis using a preclinical hyperpolarized ¹²⁹Xe (HPXe) MRI system.

Methods:

Lung injury was induced by intra-peritoneal injection of bleomycin (BLM) in 19 mice. Three weeks post-injection (when fibrosis was confirmed histologically), administration of ethyl pyruvate (EP) and alogliptin (ALG), which are down- and up-regulators of HMGB1, respectively, was commenced in six and seven of the 19 mice, respectively, and continued for a further 3 weeks. A separate sham-instilled group was formed of five mice, which were administered with saline for 6 weeks. Over the second 3-week period, the effects of disease progression and pharmacological therapy in the four groups of mice were monitored by HPXe MRI metrics of fractional ventilation and gas-exchange function.

Results:

Gas-exchange function in BLM mice was significantly reduced after 3 weeks of BLM challenge compared to sham-instilled mice (P < 0.05). Ethyl pyruvate was found to improve HPXe MRI metrics of both ventilation and gas exchange, and repair tissue damage (assessed histologically), to a similar level as sham-instilled mice (P < 0.05), whilst ALG treatment caused no significant improvement of pulmonary function.

Conclusion:

This study demonstrates the down-regulator of HMGB1, EP, as a potential therapeutic agent for pulmonary fibrosis, as assessed by a non-invasive HPXe MRI protocol.

Extracellular matrix remodeling in idiopathic pulmonary fibrosis. It is the 'bed' that counts and not 'the sleepers'

INTRODUCTION

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive interstitial lung disease characterized by irreversible fibrosis. Current disease pathogenesis assumes an aberrant wound healing process in response to repetitive injurious stimuli leading to apoptosis of epithelial cells, activation of fibroblasts and accumulation of extracellular matrix (ECM). Particularly, lung ECM is a highly dynamic structure that lies at the core of several physiological and developmental pathways. The scope of this review article is to summarize current knowledge on the role of ECM in the pathogenesis of IPF, unravel novel mechanistic data and identify future more effective therapeutic targets. Areas covered: The exact mechanisms through which lung microenvironment activates fibroblasts and inflammatory cells, regulates profibrotic signaling cascades through growth factors, integrins and degradation enzymes ultimately leading to excessive matrix deposition are discussed. Furthermore, the potential therapeutic usefulness of specific inhibitors of matrix deposition or activators of matrix degradation pathways are also presented. Expert commentary: With a gradually increasing worldwide incidence IPF still present a major challenge in clinical research due to its unknown etiopathogenesis and current ineffective treatment approaches. Today, there is an amenable need for more effective therapeutic targets and ECM components may represent one.

Efficacy of N-Acetylcysteine in Idiopathic Pulmonary Fibrosis: A Systematic Review and Meta-Analysis

There are a number of conflicting reports describing the clinical outcomes of using N-acetylcysteine for the treatment of idiopathic pulmonary fibrosis. We have, therefore, performed a meta-analysis to evaluate the efficacy of N-acetylcysteine, compared with control, for the treatment of idiopathic pulmonary fibrosis.Original controlled clinical trials evaluating the efficacy of N-acetylcysteine for the treatment of idiopathic pulmonary fibrosis were included in the analysis. Searches for relevant articles were carried out in July 2014 by 2 independent researchers using PubMed, Embase, Cochrane Central, and Google Scholar. Change in forced vital capacity, change in percentage of predicted vital capacity, change in percentage of predicted carbon monoxide diffusing capacity, changes in 6 minutes walking test distance, rate of adverse events, and rate of death were expressed as outcomes using RevMan 5.0.1.Five trials, with a total of 564 patients, were included in this meta-analysis. The meta-analysis showed that the control group had significant decreases in percentage of predicted vital capacity (standardized mean difference [SMD] = 0.37; 95% confidence interval [CI]: 0.13 to -0.62; P = 0.003) and 6 minutes walking test distance (SMD = 0.25; 95% CI: 0.02-0.48; P = 0.04). There were no statistically significant differences in forced vital capacity (SMD = 0.07; 95% CI: -0.13-0.27; P = 0.52), percentage of predicted carbon monoxide diffusing capacity (SMD = 0.12; 95% CI: -0.06-0.30; P = 0.18), rates of adverse events (odd ratio = 4.50; 95% CI: 0.19-106.41; P = 0.35), or death rates (odd ratio = 1.79; 95% CI: 0.3-5.12; P = 0.28) between the N-acetylcysteine group and the control group.N-Acetylcysteine was found to have a significant effect only on decreases in percentage of predicted vital capacity and 6 minutes walking test distance. N-acetylcysteine showed no beneficial effect on changes in forced vital capacity, changes in predicted carbon monoxide diffusing capacity, rates of adverse events, or death rates.

N-Acetylcysteine Inhibits Ventilation-Induced Collagen Accumulation in the Rat Lung

Mechanical ventilation is the most important life supportive therapy for patients with acute respiratory distress syndrome (ARDS). However, increasing evidence from clinical studies suggests that mechanical ventilation can cause lung fibrosis, which may significantly contribute to morbidity and mortality. Recent studies also found fibroproliferation occurred in early stage of ARDS with poor outcome. We have hypothesized that mechanical ventilation-induced lung injury may be a major contributor to lung fibrosis, and antioxidant could be a potential therapeutic agent for the treatment to mechanic ventilation induced fibroproliferation. We therefore used Sprague-Dawley rats that were ventilated with large tidal volume (20 ml/kg) or low tidal volume (7 ml/kg). We analyzed the time course of collagen level in the lung and the effect of N-acetylcysteine (NAC), a thiol antioxidant, on mechanical ventilation-induced collagen accumulation. In addition, normal human lung fibroblasts (NHLF) were exposed to mechanical stretch, which mimics ventilator-induced lung inflation, to evaluate the collagen secretion in culture medium. We found that ventilation-induced collagen accumulation occurred even after 2-hour ventilation. Pretreatment with NAC (140 mg/kg) inhibited collagen accumulation in lungs of rats ventilated with large tidal volume. Moreover, mechanical stretch caused the accumulation of collagen in the culture medium of NHLF, the magnitude of which was decreased with the pretreatment with NAC (1 mM). These results indicate that mechanical ventilation can induce collagen accumulation within 2 hours. NAC alleviated the collagen accumulation induced by mechanical ventilation with high tidal volume. Therefore, NAC can be considered as a good candidate in preventing ventilation-induced lung fibrosis.

Vitamin E reduces adipose tissue fibrosis, inflammation, and oxidative stress and improves metabolic profile in obesity

OBJECTIVE

To test whether enhancing the capability of adipose tissue to store lipids using antioxidant supplementation may prevent the lipotoxic effects and improve the metabolic profile of long-term obesity.

METHODS

C57BL/6J mice were randomized into three experimental groups for 28 weeks: control group (n = 10) fed chow diet (10% kcal from fat), obese group (O, n = 12) fed high-fat (HF) diet (45% kcal from fat), and obese group fed HF diet and supplemented twice a week with 150 mg of α-tocopherol (vitamin E) by oral gavage (OE, n = 12).

RESULTS

HF diet resulted in an obese phenotype with a marked insulin resistance, hypertriglyceridemia, and hepatic steatosis in O mice. Histological analysis of obese visceral adipose tissue (VAT) revealed smaller adipocytes surrounded by a fibrotic extracellular matrix and an increased macrophage infiltration, with the consequent release of proinflammatory cytokines. Vitamin E supplementation decreased oxidative stress and reduced collagen deposition in the VAT of OE mice, allowing a further expansion of the adipocytes and increasing the storage capability. As a result, circulating cytokines were reduced and hepatic steasosis, hypertriglyceridemia, and insulin sensitivity were improved.

CONCLUSIONS

Our results suggest that oxidative stress is implicated in extracellular matrix remodeling and may play an important role in metabolic regulation.

Pharmacological treatment of idiopathic pulmonary fibrosis - preclinical and clinical studies of pirfenidone, nintedanib, and N-acetylcysteine

Three recent clinical trials on the pharmacologic treatment of idiopathic pulmonary fibrosis (IPF) mark a new chapter in the management of patients suffering from this very severe fibrotic lung disease. This review article summarizes the published investigations on the preclinical studies of three novel IPF drugs, namely pirfenidone, nintedanib, and N-acetylcysteine (NAC). In addition, the study protocols, differences, and the main findings in the recent clinical trials of these pharmacological treatments are reviewed. The strategy for drug development and the timeline from the discovery to the clinical use have been very different in these regimens. Pirfenidone was discovered in 1976 but only recently received approval in most countries, and even now its exact mechanism of action is unknown. On the contrary, nintedanib (BIBF1120) was identified in large drug screening tests as a very specific inhibitor of certain tyrosine kinases, but no published data on preclinical tests existed until 2014. NAC, a mucolytic drug with an antioxidant mechanism of action was claimed to possess distinct antifibrotic properties in several experimental models but proved to be ineffective in a recent randomized placebo-controlled trial. At present, no curative treatment is available for IPF. A better understanding of the molecular mechanisms of IPF as well as relevant preclinical tests including animal models and in vitro experiments on human lung cells are needed to promote the development of therapeutic drugs.

The copper chelator tetrathiomolybdate regressed bleomycin-induced pulmonary fibrosis in mice, by reducing lysyl oxidase expressions

Pulmonary fibrosis (PF) is characterized by an increase in the number of fibroblasts and an accumulation of collagen fibers in the extracellular matrix (ECM). The members of the copper-dependent lysyl oxidase (LOX) enzyme family regulate the collagen accumulation in the ECM. Tetrathiomolybdate (TM) is a copper chelator. The present study reported the effect of TM on the expression of LOX proteins (LOX, LOXL1, and LOXL2), collagen digestion enzymes (MMP2 and MMP8), and TIMP1 (a collagenase inhibitor) in PF. The PF in mice was induced by intratracheal bleomycin instillation. Adult mice were divided into four groups: mice dissected after 21 days of the first bleomycin (0.08 mg/kg, single dose) treatment (I) and their controls (II), and mice treated with TM for 1 week (1.2 mg/day/mice for the first 4 days and 0.9 mg/day/mice for the last 3 days) after 14 days of the first bleomycin instillation and dissected in the 21st day of the experiment (III) and their controls (IV). Mice in groups III and IV were fed a low-copper (2 mg/kg) diet during the last 7 days of the experiment. The fibrosis score in the lung was determined under a microscope. The expressions of collagen-I, LOX, MMP, and TIMP1 proteins were analyzed by Western blotting in the lung. Mice lungs with fibrosis were characterized by an overexpression of collagen-I, LOX, MMP, and TIMP1 proteins in addition to an accumulation of collagen fibers. TM treatments significantly regressed the overexpression of these proteins in the fibrotic mice lung. In conclusion, TM treatments can be used for the regression of PF, by decreasing collagen-I protein expression and accumulation.

Long-term treatment with oral N-acetylcysteine: affects lung function but not sputum inflammation in cystic fibrosis subjects. A phase II randomized placebo-controlled trial

PURPOSE

To evaluate the effects of oral N-acetylcysteine (NAC), which replenishes systemic glutathione, on decreasing inflammation and improving lung function in CF airways.

METHODS

A multicenter, randomized, double-blind proof of concept study in which 70 CF subjects received NAC or placebo orally thrice daily for 24 weeks.

ENDPOINTS

primary, change in sputum human neutrophil elastase (HNE) activity; secondary, FEV(1) and other clinical lung function measures; and safety, the safety and tolerability of NAC and the potential of NAC to promote pulmonary hypertension in subjects with CF.

RESULTS

Lung function (FEV(1) and FEF(25-75%)) remained stable or increased slightly in the NAC group but decreased in the placebo group (p=0.02 and 0.02). Log(10) HNE activity remained equal between cohorts (difference 0.21, 95% CI -0.07 to 0.48, p=0.14).

CONCLUSIONS

NAC recipients maintained their lung function while placebo recipients declined (24 week FEV1 treatment effect=150 mL, p<0.02). However no effect on HNE activity and other selected biomarkers of neutrophilic inflammation were detected. Further studies on mechanism and clinical outcomes are warranted.

The mitochondrial cardiolipin remodeling enzyme lysocardiolipin acyltransferase is a novel target in pulmonary fibrosis

RATIONALE

Lysocardiolipin acyltransferase (LYCAT), a cardiolipin-remodeling enzyme regulating the 18:2 linoleic acid pattern of mammalian mitochondrial cardiolipin, is necessary for maintaining normal mitochondrial function and vascular development. We hypothesized that modulation of LYCAT expression in lung epithelium regulates development of pulmonary fibrosis.

OBJECTIVES

To define a role for LYCAT in human and murine models of pulmonary fibrosis.

METHODS

We analyzed the correlation of LYCAT expression in peripheral blood mononuclear cells (PBMCs) with the outcomes of pulmonary functions and overall survival, and used the murine models to establish the role of LYCAT in fibrogenesis. We studied the LYCAT action on cardiolipin remodeling, mitochondrial reactive oxygen species generation, and apoptosis of alveolar epithelial cells under bleomycin challenge.

MEASUREMENTS AND MAIN RESULTS

LYCAT expression was significantly altered in PBMCs and lung tissues from patients with idiopathic pulmonary fibrosis (IPF), which was confirmed in two preclinical murine models of IPF, bleomycin- and radiation-induced pulmonary fibrosis. LYCAT mRNA expression in PBMCs directly and significantly correlated with carbon monoxide diffusion capacity, pulmonary function outcomes, and overall survival. In both bleomycin- and radiation-induced pulmonary fibrosis murine models, hLYCAT overexpression reduced several indices of lung fibrosis, whereas down-regulation of native LYCAT expression by siRNA accentuated fibrogenesis. In vitro studies demonstrated that LYCAT modulated bleomycin-induced cardiolipin remodeling, mitochondrial membrane potential, reactive oxygen species generation, and apoptosis of alveolar epithelial cells, potential mechanisms of LYCAT-mediated lung protection.

CONCLUSIONS

This study is the first to identify modulation of LYCAT expression in fibrotic lungs and offers a novel therapeutic approach for ameliorating lung inflammation and pulmonary fibrosis.

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.

Interleukin-1β attenuates myofibroblast formation and extracellular matrix production in dermal and lung fibroblasts exposed to transforming growth factor-β1

One of the most potent pro-fibrotic cytokines is transforming growth factor (TGFβ). TGFβ is involved in the activation of fibroblasts into myofibroblasts, resulting in the hallmark of fibrosis: the pathological accumulation of collagen. Interleukin-1β (IL1β) can influence the severity of fibrosis, however much less is known about the direct effects on fibroblasts. Using lung and dermal fibroblasts, we have investigated the effects of IL1β, TGFβ1, and IL1β in combination with TGFβ1 on myofibroblast formation, collagen synthesis and collagen modification (including prolyl hydroxylase, lysyl hydroxylase and lysyl oxidase), and matrix metalloproteinases (MMPs). We found that IL1β alone has no obvious pro-fibrotic effect on fibroblasts. However, IL1β is able to inhibit the TGFβ1-induced myofibroblast formation as well as collagen synthesis. Glioma-associated oncogene homolog 1 (GLI1), the Hedgehog transcription factor that is involved in the transformation of fibroblasts into myofibroblasts is upregulated by TGFβ1. The addition of IL1β reduced the expression of GLI1 and thereby also indirectly inhibits myofibroblast formation. Other potentially anti-fibrotic effects of IL1β that were observed are the increased levels of MMP1, −2, −9 and −14 produced by fibroblasts exposed to TGFβ1/IL1β in comparison with fibroblasts exposed to TGFβ1 alone. In addition, IL1β decreased the TGFβ1-induced upregulation of lysyl oxidase, an enzyme involved in collagen cross-linking. Furthermore, we found that lung and dermal fibroblasts do not always behave identically towards IL1β. Suppression of COL1A1 by IL1β in the presence of TGFβ1 is more pronounced in lung fibroblasts compared to dermal fibroblasts, whereas a higher upregulation of MMP1 is seen in dermal fibroblasts. The role of IL1β in fibrosis should be reconsidered, and the differences in phenotypical properties of fibroblasts derived from different organs should be taken into account in future anti-fibrotic treatment regimes.

Interleukin-1β attenuates myofibroblast formation and extracellular matrix production in dermal and lung fibroblasts exposed to transforming growth factor-β1

One of the most potent pro-fibrotic cytokines is transforming growth factor (TGFβ). TGFβ is involved in the activation of fibroblasts into myofibroblasts, resulting in the hallmark of fibrosis: the pathological accumulation of collagen. Interleukin-1β (IL1β) can influence the severity of fibrosis, however much less is known about the direct effects on fibroblasts. Using lung and dermal fibroblasts, we have investigated the effects of IL1β, TGFβ1, and IL1β in combination with TGFβ1 on myofibroblast formation, collagen synthesis and collagen modification (including prolyl hydroxylase, lysyl hydroxylase and lysyl oxidase), and matrix metalloproteinases (MMPs). We found that IL1β alone has no obvious pro-fibrotic effect on fibroblasts. However, IL1β is able to inhibit the TGFβ1-induced myofibroblast formation as well as collagen synthesis. Glioma-associated oncogene homolog 1 (GLI1), the Hedgehog transcription factor that is involved in the transformation of fibroblasts into myofibroblasts is upregulated by TGFβ1. The addition of IL1β reduced the expression of GLI1 and thereby also indirectly inhibits myofibroblast formation. Other potentially anti-fibrotic effects of IL1β that were observed are the increased levels of MMP1, -2, -9 and -14 produced by fibroblasts exposed to TGFβ1/IL1β in comparison with fibroblasts exposed to TGFβ1 alone. In addition, IL1β decreased the TGFβ1-induced upregulation of lysyl oxidase, an enzyme involved in collagen cross-linking. Furthermore, we found that lung and dermal fibroblasts do not always behave identically towards IL1β. Suppression of COL1A1 by IL1β in the presence of TGFβ1 is more pronounced in lung fibroblasts compared to dermal fibroblasts, whereas a higher upregulation of MMP1 is seen in dermal fibroblasts. The role of IL1β in fibrosis should be reconsidered, and the differences in phenotypical properties of fibroblasts derived from different organs should be taken into account in future anti-fibrotic treatment regimes.