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

Comprehensive review of potential drugs with anti-pulmonary fibrosis properties

Pulmonary fibrosis is a chronic and progressive lung disease characterized by the accumulation of scar tissue in the lungs, which leads to impaired lung function and reduced quality of life. The prognosis for idiopathic pulmonary fibrosis (IPF), which is the most common form of pulmonary fibrosis, is generally poor. The median survival for patients with IPF is estimated to be around 3-5 years from the time of diagnosis. Currently, there are two approved drugs (Pirfenidone and Nintedanib) for the treatment of IPF. However, Pirfenidone and Nintedanib are not able to reverse or cure pulmonary fibrosis. There is a need for new pharmacological interventions that can slow or halt disease progression and cure pulmonary fibrosis. This review aims to provide an updated overview of current and future drug interventions for idiopathic pulmonary fibrosis, and to summarize possible targets of potential anti-pulmonary fibrosis drugs, providing theoretical support for further clinical combination therapy or the development of new drugs.

Respiratory infection risk in primary Sjögren's syndrome complicated with interstitial lung disease: a retrospective study

OBJECTIVES

To explore clinical and laboratory characteristics of primary Sjögren's syndrome (pSS) complicated with interstitial lung disease (ILD) and investigate the risk factors for respiratory infections in pSS-ILD.

METHODS

A cohort of 162 pSS-ILD patients in Peking University People's Hospital from 2015 to 2020 were included, and all medical records were completely collected. We screened 53 patients suffering from respiratory infections as study cases, compared with 109 age- and sex-matched controls. Differences between infection group and control group were compared. Univariate and multivariate binary logistic regression tests were conducted to identify potential risk factors for respiratory infections in pSS-ILD patients.

RESULTS

Among 162 pSS-ILD patients, 32.72% (53/162) suffered from respiratory infections. The most frequent type of ILD was nonspecific interstitial pneumonia (32.08%, 51/159), and the most common type of pathogen was bacteria (64.25%, 34/53). Infection group showed higher levels of ESSDAI (P < 0.001), CRP (P < 0.001), ESR (P = 0.003), and C3 (P = 0.020) but lower level of DLCO-SB (P = 0.015). Univariate logistic model revealed that PAH and the use of glucocorticoid increased infection risk in pSS-ILD patients. On multivariate logistic regression analysis, PAH (OR = 3.993, 95% CI = 1.192-13.373, P = 0.025) and severe reduction of DLCO (DLCO-SB < 40%, OR = 4.625, 95% CI = 1.281-16.702, P = 0.019) were significantly associated with increased risk of respiratory infections in pSS-ILD patients.

CONCLUSION

Among pSS-ILD patients, the most frequent type of ILD was nonspecific interstitial pneumonia. In patients with infection, bacteria were the most common pathogen. Higher levels of ESSDAI, CRP, ESR, and C3 may be correlated with increased infection risk. PAH and reduction of DLCO were identified as independent risk factors. Key Points • ILD and infectious diseases severely affect pSS patient conditions. • Higher levels of ESSDAI, CRP, ESR, and C3 may be correlated with increased infection risks in pSS-ILD. • PAH and reduction of DLCO were identified as independent risk factors for lower respiratory infection.

Efficacy and Safety of Hydrogen Therapy in Patients with Early-Stage Interstitial Lung Disease: A Single-Center, Randomized, Parallel-Group Controlled Trial

Purpose

Several in vivo experiments have shown that molecular hydrogen is a promising therapeutic agent for interstitial lung diseases (ILD). In this study, hydrogen therapy was investigated to determine whether it is superior to N-Acetylcysteine (NAC) for the treatment of patients with early-stage ILD.

Patients and Methods

A prospective, single-center, randomized, controlled clinical trial was conducted in 87 patients with early-stage ILD. Hydrogen or NAC therapy was randomly assigned (1:1 ratio) to the eligible patients. The primary endpoint was the change in the high-resolution computed tomography (HRCT) and composite physiologic index (CPI) scores from baseline to week 48. Pulmonary function was evaluated as a secondary endpoint, and adverse events were recorded for safety analysis.

Results

The rate of HRCT image improvement from the baseline in the HW group (63.6%) was higher than that in the NAC group (39.5%). A significant decrease in CPI and improvement in DLCO-sb were observed in the hydrogen group compared with those in the control group. Changes in other pulmonary function parameters, including FVC, FEV1, FEV1/FVC%, and TLC, were not significantly different between the two groups. Adverse events were reported in 7 (15.9%) patients in the HW group and 10 (23.3%) patients in the NAC group, but the difference was not significant (P=0.706).

Conclusion

Hydrogen therapy exhibits superior efficacy and acceptable safety compared with NAC therapy in patients with early-stage ILD.

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.

Individualised Exercise Training Enhances Antioxidant Buffering Capacity in Idiopathic Pulmonary Fibrosis

Exercise training is recommended for patients with idiopathic pulmonary fibrosis (IPF); however, the mechanism(s) underlying its physiological benefits remain unclear. We investigated the effects of an individualised aerobic interval training programme on exercise capacity and redox status in IPF patients. IPF patients were recruited prospectively to an 8-week, twice-weekly cardiopulmonary exercise test (CPET)-derived structured responsive exercise training programme (SRETP). Systemic redox status was assessed pre- and post-CPET at baseline and following SRETP completion. An age- and sex-matched non-IPF control cohort was recruited for baseline comparison only. At baseline, IPF patients (n = 15) had evidence of increased oxidative stress compared with the controls as judged by; the plasma reduced/oxidised glutathione ratio (median, control 1856 vs. IPF 736 p = 0.046). Eleven IPF patients completed the SRETP (median adherence 88%). Following SRETP completion, there was a significant improvement in exercise capacity assessed via the constant work-rate endurance time (+82%, p = 0.003). This was accompanied by an improvement in post-exercise redox status (in favour of antioxidants) assessed via serum total free thiols (median increase, +0.26 μmol/g protein p = 0.005) and total glutathione concentration (+0.73 μM p = 0.03), as well as a decrease in post-exercise lipid peroxidation products (-1.20 μM p = 0.02). Following SRETP completion, post-exercise circulating nitrite concentrations were significantly lower compared with baseline (-0.39 μM p = 0.04), suggestive of exercise-induced nitrite utilisation. The SRETP increased both endurance time and systemic antioxidant capacity in IPF patients. The observed reduction in nitrite concentrations provides a mechanistic rationale to investigate nitrite/nitrate supplementation in IPF patients.

Trials and Treatments: An Update on Pharmacotherapy for Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive fibrosing interstitial lung disease that occurs predominantly in the older population. There is increasing incidence and prevalence in IPF globally. The emergence of anti-fibrotic therapies in the last decade have improved patient survival though a cure is yet to be developed. In this review article, we aim to summarize the existing and novel pharmacotherapies for the treatment of IPF (excluding treatments for acute exacerbations), focusing on the current knowledge on the pathophysiology of the disease, mechanism of action of the drugs, and clinical trials.

Role of Ferroptosis in Fibrotic Diseases

Ferroptosis is a unique and pervasive form of regulated cell death driven by iron-dependent phospholipid peroxidation. It results from disturbed cellular metabolism and imbalanced redox homeostasis and is regulated by various cellular metabolic pathways. Recent preclinical studies have revealed that ferroptosis may be an attractive therapeutic target in fibrotic diseases, such as liver fibrosis, pulmonary fibrosis, kidney fibrosis, and myocardial fibrosis. This review summarizes the latest knowledge on the regulatory mechanism of ferroptosis and its roles in fibrotic diseases. These updates may provide a novel perspective for the treatment of fibrotic diseases as well as future research.

N-acetylcysteine (NAC) and Its Role in Clinical Practice Management of Cystic Fibrosis (CF): A Review

N-acetylcysteine is the acetylated form of the amino acid L-cysteine and a precursor to glutathione (GSH). It has been known for a long time as a powerful antioxidant and as an antidote for paracetamol overdose. However, other activities related to this molecule have been discovered over the years, making it a promising drug for diseases such as cystic fibrosis (CF). Its antioxidant activity plays a key role in CF airway inflammation and redox imbalance. Furthermore, this molecule appears to play an important role in the prevention and eradication of biofilms resulting from CF airway infections, in particular that of Pseudomonas aeruginosa. The aim of this review is to provide an overview of CF and the role that NAC could play in preventing and eliminating biofilms, as a modulator of inflammation and as an antioxidant, restoring the redox balance within the airways in CF patients. To do this, NAC can act alone, but it can also be used as an adjuvant molecule to known drugs (antibiotics/anti-inflammatories) to increase their activity.

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.

Involvement of 4-hydroxy-2-nonenal in the pathogenesis of pulmonary fibrosis

Pulmonary fibrosis is a chronic progressive disease with high incidence, prevalence, and mortality rates worldwide. It is characterized by excessive accumulation of extracellular matrix in the lung parenchyma. The cellular and molecular mechanisms involved in its pathogenesis are complex, and some are still unknown. Several studies indicate that oxidative stress, characterized by overproduction of 4-hydroxy-2-nonenal (4-HNE), is an important player in pulmonary fibrosis. 4-HNE is a highly reactive compound derived from polyunsaturated fatty acids that can react with proteins, phospholipids, and nucleic acids. Thus, many of the altered cellular mechanisms that contribute to this disease can be explained by the participation of 4-HNE. Here, we summarize the current knowledge on the molecular states and signal transduction pathways that contribute to the pathogenesis of pulmonary fibrosis. Furthermore, we describe the participation of 4-HNE in various mechanisms involved in pulmonary fibrosis development, with a focus on the cell populations involved in the initiation, development, and maintenance of the fibrotic process, mainly alveolar cells, endothelial cells, macrophages, and inflammatory cells. Due to its characteristic activity as a second messenger, 4-HNE, in addition to being a consequence of oxidative stress, can support maintenance of the inflammatory and fibrotic process by spreading the effects of reactive oxygen species (ROS). Thus, regulation of 4-HNE levels could be a viable strategy to reduce its effects on the mechanisms involved in pulmonary fibrosis development.

Serum Biomarkers in Differential Diagnosis of Idiopathic Pulmonary Fibrosis and Connective Tissue Disease-Associated Interstitial Lung Disease

Introduction: The goal of this study is to determine whether Advanced glycosylated end-products (AGE), Advanced oxidation protein products (AOPP) and Matrix metalloproteinase 7 (MMP7) could be used as differential biomarkers for idiopathic pulmonary fibrosis (IPF) and connective tissue disease-associated interstitial lung disease (CTD-ILD). Method: Seventy-three patients were enrolled: 29 with IPF, 14 with CTD-ILD, and 30 healthy controls. The study included a single visit by participants. A blood sample was drawn and serum was analysed for AGE using spectrofluorimetry, AOPP by spectrophotometry, and MMP7 using sandwich-type enzyme-linked immunosorbent assay. Results: AGE, AOPP and MMP7 serum levels were significantly higher in both IPF and CTD-ILD patients versus healthy controls; and AGE was also significantly elevated in CTD-ILD compared to the IPF group. AGE plasma levels clearly distinguished CTD-ILD patients from healthy participants (AUC = 0.95; 95% IC 0.86–1), whereas in IPF patients, the distinction was moderate (AUC = 0.78; 95% IC 0.60–0.97). Conclusion: In summary, our results provide support for the potential value of serum AGE, AOPP and MMP7 concentrations as diagnostic biomarkers in IPF and CTD-ILD to differentiate between ILD patients and healthy controls. Furthermore, this study provides evidence, for the first time, for the possible use of AGE as a differential diagnostic biomarker to distinguish between IPF and CTD-ILD. The value of these biomarkers as additional tools in a multidisciplinary approach to IPF and CTD-ILD diagnosis needs to be considered and further explored. Multicentre studies are necessary to understand the role of AGE in differential diagnosis.

Safety of N-Acetylcysteine at High Doses in Chronic Respiratory Diseases: A Review

N-Acetylcysteine (NAC) is widely used in respiratory medicine, with a maximum licensed dose in chronic use of 600 mg/day; however, some clinical trials have studied the efficacy of NAC at higher doses. The aim of this review was to evaluate the adverse effects profile of NAC at higher than the standard dose in chronic respiratory diseases to establish a risk-benefit ratio in increasing the daily dose; therefore, studies using NAC at a dose of at least 600 mg/day were selected. Forty-one articles where NAC has been used at 600 mg and above, up to 3000 mg/day, and with a specific report on safety, were considered. Most of the studies used oral NAC and were conducted on patients with chronic obstructive pulmonary disease, idiopathic pulmonary fibrosis, bronchiectasis, chronic bronchitis and cystic fibrosis. In general, the safety profile was similar at both the high and standard doses with the oral formulation; gastrointestinal symptoms were reported but they were no more common than in the control group.

Microstructured Lipid Carriers (MLC) Based on N-Acetylcysteine and Chitosan Preventing Pseudomonas aeruginosa Biofilm

The aim of this work was the development of microstructured lipid carriers (MLC) based on chitosan (CH) and containing N-acetylcysteine (NAC), a mucolytic and antioxidant agent, to inhibit the formation of Pseudomonas aeruginosa biofilm. MLC were prepared using the high shear homogenization technique. The MLC were characterized for morphology, particle size, Z potential, encapsulation efficiency and drug release. The antioxidant properties of NAC-loaded microstructured carriers were evaluated through an in vitro spectrophotometer assay. Finally, the activity of NAC-CH-MLC on biofilm production by Pseudomonas aeruginosa was also evaluated. Results obtained from this study highlighted that the use of chitosan into the inner aqueous phase permitted to obtain microstructured particles with a narrow size range and with good encapsulation efficiency. NAC-loaded MLC showed higher antioxidant activity than the free molecule, demonstrating how encapsulation increases the antioxidant effect of the molecule. Furthermore, the reduction of biofilm growth resulted extremely high with MLC being 64.74% ± 6.2% and 83.74% ± 9.95%, respectively, at 0.5 mg/mL and 2 mg/mL. In conclusion, this work represents a favorable technological strategy against diseases in which bacterial biofilm is relevant, such as cystic fibrosis.

Pirfenidone plus inhaled N-acetylcysteine for idiopathic pulmonary fibrosis: a randomised trial

BACKGROUND

A randomised controlled trial in Japan showed that inhaled N-acetylcysteine monotherapy stabilised serial decline in forced vital capacity (FVC) in some patients with early idiopathic pulmonary fibrosis (IPF). However, the efficacy and tolerability of combination therapy with an antifibrotic agent and inhaled N-acetylcysteine are unknown.

METHODS

This 48-week, randomised, open-label, multicentre phase 3 trial compared the efficacy and tolerability of combination therapy with pirfenidone plus inhaled N-acetylcysteine 352.4 mg twice daily with the results for pirfenidone alone in patients with IPF. The primary end-point was annual rate of decline in FVC. Exploratory efficacy measurements included serial change in diffusing capacity of the lung for carbon monoxide (D _LCO) and 6-min walk distance (6MWD), progression-free survival (PFS), incidence of acute exacerbation, and tolerability.

RESULTS

81 patients were randomly assigned in a 1:1 ratio to receive pirfenidone plus inhaled N-acetylcysteine (n=41) or pirfenidone (n=40). The 48-week rate of change in FVC was -300 mL and -123 mL, respectively (difference -178 mL, 95% CI -324--31 mL; p=0.018). Serial change in D _LCO, 6MWD, PFS and incidence of acute exacerbation did not significantly differ between the two groups. The incidence of adverse events (n=19 (55.9%) for pirfenidone plus N-acetylcysteine; n=18 (50%) for pirfenidone alone) was similar between groups.

CONCLUSIONS

Combination treatment with inhaled N-acetylcysteine and pirfenidone is likely to result in worse outcomes for IPF.

Amelioration of Bleomycin and Methotrexate-Induced Pulmonary Toxicity by Serratiopeptidase and Fisetin

Pulmonary toxicity by anticancer drugs often leads to discontinuation of therapy or switching the therapy to alternative drugs. In the present study, serratiopeptidase (SPTD) and fisetin (FST) were evaluated as chemoprotectant to counteract the pulmonary toxicity induced by BLM and MTX. Single dose of MTX (20 mg/kg) by intraperitoneal and BLM (5 mg/kg) by intra-tracheal route was administered on 7^th day of study. SPTD (20 mg/kg), FST (25 mg/kg), and NAC (250 mg/kg) and combinations of SPTD + NAC, SPTD + FST, and FST + NAC were administered through oral gavage for 14 days. SPTD and FST showed significant (p < 0.05) effect in MTX-induced lung toxicity by increasing reduced glutathione (GSH) and decreasing malondialdehyde (MDA), hydroxyproline (HXP), and collagen. SPTD and NAC showed significant (p < 0.05) effect in BLM-induced pulmonary toxicity by increasing GSH and decreasing MDA, HXP, and collagen whereas FST was not much effective. In combination study, SPTD + NAC combination showed significant (p < 0.05) effect in BLM- and MTX- induced lung injury whereas other combinations did not prove to be highly effective. SPTD can be recommended along with BLM and MTX in chemotherapy protocol alone and in combination with NAC.

Lipid Peroxidation, GSH Depletion, and SLC7A11 Inhibition Are Common Causes of EMT and Ferroptosis in A549 Cells, but Different in Specific Mechanisms

Epithelial-mesenchymal transition (EMT) induced by transforming growth factor-β1 (TGF-β1) is thought to be involved in the pathogenesis of pulmonary fibrosis. Emerging evidence suggested that there are some common causes between ferroptosis and pulmonary fibrosis. The interaction of EMT and ferroptosis and its mechanism were investigated by detecting the expression levels of α-smooth muscle actin (α-SMA), E-cadherin, solute carrier family 7 member 11 (SLC7A11), and glutathione peroxidase 4 (GPX4) and measuring the contents of reactive oxygen species (ROS), malondialdehyde (MDA), and glutathione (GSH). The cellular morphology and ultrastructure of mitochondria were studied by microscope and transmission electron microscope (TEM), respectively. The results showed that ferroptosis in A549 cells was induced by Erastin, which decreased the expression levels of E-cadherin (E-Ca), α-SMA, and SLC7A11, accompanied with ROS and MDA increase, as well as GSH decrease. TGF-β1 promoted ultrastructure variation of mitochondria similar to ferroptosis and mesenchymal changes in morphology during EMT of A549 cells, accompanied with reduced GSH content and expression of SLC7A11, as well as ROS and MDA increase. Ferrostatin-1 (Fer-1) recovered ferroptosis induced by Erastin, but had no effect on the morphological change caused by TGF-β1. Furthermore, Fer-1 reduced ROS and MDA production, and increased SLC7A11 expression in the early subsequently increased GSH. However, the effects of Fer-1 on above indicators were different in time. The expression of GPX4 had no significant change during EMT induced by TGF-β1 and ferroptosis induced by Erastin in A549 cells. It is indicating that Erastin promoted the de-epithelialization of lung epithelial cells, but inhibited the process of myofibroblast differentiation; Fer-1 could partially inhibit EMT induced by TGF-β1, but reverse ferroptosis induced by Erastin. TGF-β1 could delay the ferroptosis, but could not prevent it. Lipid peroxidation, GSH depletion, and SLC7A11 inhibition are common causes of EMT and ferroptosis in A549 cells, but different in specific mechanisms. The exact effects of GPX4 involved in EMT and ferroptosis in A549 cells need further study.

Airway Redox Homeostasis and Inflammation Gone Awry: From Molecular Pathogenesis to Emerging Therapeutics in Respiratory Pathology

As aerobic organisms, we are continuously and throughout our lifetime subjected to an oxidizing atmosphere and, most often, to environmental threats. The lung is the internal organ most highly exposed to this milieu. Therefore, it has evolved to confront both oxidative stress induced by reactive oxygen species (ROS) and a variety of pollutants, pathogens, and allergens that promote inflammation and can harm the airways to different degrees. Indeed, an excess of ROS, generated intrinsically or from external sources, can imprint direct damage to key structural cell components (nucleic acids, sugars, lipids, and proteins) and indirectly perturb ROS-mediated signaling in lung epithelia, impairing its homeostasis. These early events complemented with efficient recognition of pathogen- or damage-associated recognition patterns by the airway resident cells alert the immune system, which mounts an inflammatory response to remove the hazards, including collateral dead cells and cellular debris, in an attempt to return to homeostatic conditions. Thus, any major or chronic dysregulation of the redox balance, the air-liquid interface, or defects in epithelial proteins impairing mucociliary clearance or other defense systems may lead to airway damage. Here, we review our understanding of the key role of oxidative stress and inflammation in respiratory pathology, and extensively report current and future trends in antioxidant and anti-inflammatory treatments focusing on the following major acute and chronic lung diseases: acute lung injury/respiratory distress syndrome, asthma, chronic obstructive pulmonary disease, pulmonary fibrosis, and cystic fibrosis.

Efficacy, safety, and tolerability of combined pirfenidone and N-acetylcysteine therapy: a systematic review and meta-analysis

BACKGROUND

While antifibrotic drugs significantly decrease lung function decline in idiopathic pulmonary fibrosis (IPF), there is still an unmet need to halt disease progression. Antioxidative therapy with N-acetylcysteine (NAC) is considered a potential additional therapy that can be combined with antifibrotics in some patients in clinical practice. However, data on the efficacy, tolerability, and safety of this combination are scarce. We performed a systematic review and meta-analysis to appraise the safety, tolerability, and efficacy of the combination compared to treatment with pirfenidone alone.

METHODS

We systematically reviewed all the published studies with combined pirfenidone (PFD) and NAC (PFD + NAC) treatment in IPF patients. The primary outcomes referred to decline in pulmonary function tests (PFTs) and the rates of IPF patients with side effects.

RESULTS

In the meta-analysis, 6 studies with 319 total IPF patients were included. The PFD + NAC group was comparable to the PFD alone group in terms of the predicted forced vital capacity (FVC%) and predicted diffusion capacity for carbon monoxide (DLco%) from treatment start to week 24. Side effects and treatment discontinuation rates were also comparable in both groups.

CONCLUSION

This systematic review and meta-analysis suggests that combination with NAC does not alter the efficacy, safety, or tolerability of PFD in comparison to PFD alone in IPF patients.

Redox Imbalance in Idiopathic Pulmonary Fibrosis: A Role for Oxidant Cross-Talk Between NADPH Oxidase Enzymes and Mitochondria

Significance: Idiopathic pulmonary fibrosis (IPF) is a progressive age-related lung disease with a median survival of only 3 years after diagnosis. The pathogenic mechanisms behind IPF are not clearly understood, and current therapeutic approaches have not been successful in improving disease outcomes. Recent Advances: IPF is characterized by increased production of reactive oxygen species (ROS), primarily by NADPH oxidases (NOXes) and mitochondria, as well as altered antioxidant defenses. Recent studies have identified the NOX isoform NOX4 as a key player in various important aspects of IPF pathology. In addition, mitochondrial dysfunction is thought to enhance pathological features of IPF, in part by increasing mitochondrial ROS (mtROS) production and altering cellular metabolism. Recent findings indicate reciprocal interactions between NOX enzymes and mitochondria, which affect regulation of NOX activity as well as mitochondrial function and mtROS production, and collectively promote epithelial injury and profibrotic signaling. Critical Issues and Future Directions: The precise molecular mechanisms by which ROS from NOX or mitochondria contribute to IPF pathology are not known. This review summarizes the current knowledge with respect to the various aspects of ROS imbalance in the context of IPF and its proposed roles in disease development, with specific emphasis on the importance of inappropriate NOX activation, mitochondrial dysfunction, and the emerging evidence of NOX-mitochondria cross-talk as important drivers in IPF pathobiology.

Clinical importance of Bcl-2-like 11 deletion polymorphism in idiopathic pulmonary fibrosis

Background

Reactive oxygen species (ROS) can play a role in the pathogenesis of Idiopathic Pulmonary Fibrosis (IPF) by contributing to epithelial damage. Bcl-2-like 11 (BIM) is involved in the generation of ROS via forkhead box O3 (FOXO3), and a BIM deletion polymorphism related to apoptosis has been reported to be specific to Asians. Here we examine the clinical features of IPF in patients with BIM deletion polymorphism.

Methods

In this single-center retrospective study, we reviewed the medical records of 63 patients with IPF who were treated at our hospital from January 2006 through April 2018. Patients with and without BIM deletion polymorphism were compared in relation to clinical characteristics, pulmonary function test results, frequency of acute exacerbation (AE)-IPF, and redox status [including oxidized glutathione (GSSG), reduced glutathione (GSH), 8-hydroxy-2'-deoxyguanosine (8-OHdG), and 8-isoprostane (8-iso)] at baseline and at 1 and 2 years after treatment.

Results

No fatal AE-IPF occurred in patients with BIM deletion polymorphism (0% vs. 36.4% of polymorphism-negative cases; P=0.038). Change in forced vital capacity from baseline (ΔFVC) at 2 years was significantly lower in patients with the BIM deletion polymorphism than in those without the polymorphism (‒0.42±0.50 vs. ‒0.88±0.83 L, respectively; P=0.045). Total blood glutathione (tGSH) was significantly higher in patients with the deletion polymorphism than in those without the polymorphism (988±48.3 vs. 858±25.8 µM, respectively; P=0.042). 8-iso was significantly lower in the former group (246.1±81.6 vs. 400.9±334.1 pg/mL, respectively; P=0.022).

Conclusions

IPF patients with BIM deletion polymorphism had a good redox balance and may thus have a better clinical outcome than patients without this polymorphism.

Chinese Herbal Medicines Compared with N-Acetylcysteine for the Treatment of Idiopathic Pulmonary Fibrosis: A Systematic Review of Randomized Controlled Trials

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a major global health problem. The prevalence of the disease appears to be increasing. There is no curative therapy for IPF except lung transplantation. Chinese herbal medicines (CHMs) are showing promise for treatment of IPF. However, their effectiveness and safety are still unclear and deserve further investigation. The aim of this systematic review is to access the efficacy and safety of CHMs in treating IPF.

METHODS

The protocol of this review is registered at PROSPERO. We searched seven main databases for randomized clinical trials (RCTs) on CHMs for IPF from their inception to June 4, 2018. The methodological quality of RCTs was assessed using the Cochrane risk of bias tool. All trials included were analyzed according to the criteria of the Cochrane Handbook. Review Manager 5.3, R-3.5.2 software, and Grade pro GDT web solution were used for data synthesis and analysis.

RESULTS

Thirteen randomized clinical trials enrolling 733 patients were included. All trials included had clear outcome indicators. The methodological quality of included trials was generally "poor." Few trials reported methods of randomization. One trial on Xuefu-zhuyu capsule assessed rate of acute exacerbation and mortality after treatment for 72 weeks and found no statistically significant difference between two groups. This meta-analysis demonstrated a significant improvement in QOL of IPF patients when CHMs was applied or combined with conventional medicine treatment. 6MWT was significantly improved in IPF patients after using CHMs or combined with conventional medicine treatment. CHMs treatment also had a certain improvement in TLC and DLCO, but the effect on FVC was not significant. Besides, CHMs failed to provide benefits in terms of PaO2. The reported adverse events were not obvious and severe.

CONCLUSIONS

Some CHMs seem effective and safe as alternative remedies for patients with IPF, suggesting that further study of CHMs in the treatment of IPF is warranted. Although this systematic review suggests that CHMs may have positive effect on quality of life, 6-minute walk test distance, and lung function (TLC, DLOC%) and seem to be relatively safe during the course of treatment, the results must be treated with great caution because of the methodological flaws of the included trials. Long-term and high-quality trials are needed in the future to provide clear evidence for the use of CHMs.

Evaluation of oxidative stress biomarkers in idiopathic pulmonary fibrosis and therapeutic applications: a systematic review

INTRODUCTION

Idiopathic pulmonary fibrosis (IPF), a fatal lung disease of unknown origin, is characterized by chronic and progressive fibrosing interstitial pneumonia which progressively impairs lung function. Oxidative stress is one of the main pathogenic pathways in IPF. The aim of this systematic review was to describe the type of markers of oxidative stress identified in different biological specimens and the effects of antioxidant therapies in patients with IPF.

METHODS

We conducted a systematic search of publications listed in electronic databases (Pubmed, Web of Science, Scopus and Google Scholar) from inception to October 2017. Two investigators independently reviewed all identified articles to determine eligibility.

RESULTS

After a substantial proportion of the initially identified articles (n = 554) was excluded because they were duplicates, abstracts, irrelevant, or did not meet the selection criteria, we identified 30 studies. In each study, we critically appraised the type, site (systemic vs. local, e.g. breath, sputum, expired breath condensate, epithelial lining fluid, bronchoalveolar lavage, and lung tissue specimens), and method used for measuring the identified oxidative stress biomarkers. Furthermore, the current knowledge on antioxidant therapies in IPF was summarized.

CONCLUSIONS

A number of markers of oxidative stress, with individual advantages and limitations, have been described in patients with IPF. Nevertheless, trials of antioxidant treatments have been unable to demonstrate consistent benefits, barring recent pharmacogenomics data suggesting different results in specific genotype subgroups of patients with IPF.

The topical study of inhaled drug (salbutamol) delivery in idiopathic pulmonary fibrosis

Background

Our aim was to investigate total and regional lung delivery of salbutamol in subjects with idiopathic pulmonary fibrosis (IPF).

Methods

The TOPICAL study was a 4-period, partially-randomised, controlled, crossover study to investigate four aerosolised approaches in IPF subjects. Nine subjects were randomised to receive ^99mTechnetium-labelled monodisperse salbutamol (1.5 μm or 6 μm; periods 1 and 2). Subjects also received radio-labelled salbutamol using a polydisperse nebuliser (period 3) and unlabelled salbutamol (400 μg) using a polydisperse pressurized metered dose inhaler with volumatic spacer (pMDI; period 4).

Results

Small monodisperse particles (1.5 μm) achieved significantly better total lung deposition (TLD, mean % ± SD) than larger particles (6 μm), where polydisperse nebulisation was poor; (TLD, 64.93 ± 10.72; 50.46 ± 17.04; 8.19 ± 7.72, respectively). Small monodisperse particles (1.5 μm) achieved significantly better lung penetration (mean % ± SD) than larger particles (6 μm), and polydisperse nebulisation showed lung penetration similar to the small particles; PI (mean ± SD) 0.8 ± 0.16, 0.49 ± 0.21, and 0.73 ± 0.19, respectively. Higher dose-normalised plasma salbutamol levels were observed following monodisperse 1.5 μm and 6 μm particles, compared to polydisperse pMDI inhalation, while lowest plasma levels were observed following polydisperse nebulisation.

Conclusion

Our data is the first systematic investigation of inhaled drug delivery in fibrotic lung disease. We provide evidence that inhaled drugs can be optimised to reach the peripheral areas of the lung where active scarring occurs in IPF.

Trial registration

This trial was registered on clinicaltrials.gov (NCT01457261).

Electronic supplementary material

The online version of this article (10.1186/s12931-018-0732-0) contains supplementary material, which is available to authorized users.

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.

Analysis of blood neutrophil elastase, glutathione levels and pathological findings in postoperative acute exacerbation of idiopathic pulmonary fibrosis associated with lung cancer: Two case reports

Acute exacerbation (AE) of idiopathic pulmonary fibrosis (IPF) is characterized by severe worsening dyspnea and high mortality. It has been proven that the serum neutrophil elastase (NE) level, in addition to the serum Krebs von den Lungen-6 (KL-6) and surfactant protein-D (SP-D) levels, was elevated in patients with IPF-AE. Glutathione (GSH) is the major antioxidant involved in cell metabolism and survival. It is also known that IPF is characterized by reduced GSH levels in bronchoalveolar lavage fluid and blood. Case 1 was a 67-year-old man who was referred to our hospital complaining of a 2-year history of progressive dyspnea on exertion (DOE). The patient was initially diagnosed with IPF, followed by inhaled N-acetylcysteine monotherapy. Two years later, left upper lobectomy with lymph node dissection was performed due to primary lung cancer, which was large-cell neuroendocrine carcinoma (pT2aN2M0, stage IIIA). Five days after lung surgery, the patient developed AE. Case 2 was a 67-year-old man who was referred to our hospital with suspected lung cancer, complaining of dry cough and DOE. The patient underwent left upper lobectomy with lymph node dissection for primary lung cancer, which was diagnosed as well-differentiated adenocarcinoma (pT2aN2M0, stage IIIA). Ten days after lung surgery, the patient developed AE. The levels of biomarkers, such as serum NE, redox balance [reduced GSH (rGSH)/oxidized GSH (GSSG)] in the blood, as well as the correlation between serial changes of these biomarkers and prognosis, were analyzed in 2 patients with postoperative IPF-AE associated with lung cancer. Interestingly, the serial changes of the serum rGSH/GSSG ratio may suggest the possibility of predicting the onset of postoperative AE and/or survival, along with serum NE levels.

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.