Oxidative Stress-induced Lung Injury Research Articles

Hispidin attenuates bleomycin-induced idiopathic pulmonary fibrosis via an anti-oxidative effect in A549 cells

Idiopathic pulmonary fibrosis (IPF) is a serious and irreversible chronic lung disease. Bleomycin (BLM) is an anticancer drug, which can cause severe lung toxicity. The main target of oxidative stress-induced lung injury is alveolar epithelial cells, which lead to interstitial fibrosis. The present study investigated whether hispidin (HP), which has excellent antioxidant activity, attenuates bleomycin-induced pulmonary fibrosis via anti-oxidative effects in A549 cells. We found that hispidin reduced bleomycin-induced fibrosis of A549 cells by reducing reactive oxygen species (ROS) levels and inhibiting epithelial-mesenchymal transition. Taken together, our data suggest that hispidin has therapeutic potential in preventing bleomycin-induced pulmonary fibrosis.

Tolerogenic signaling of alveolar macrophages induces lung adaptation to oxidative injury

Inhaled oxidative toxicants present in ambient air cause airway epithelial injury, inflammation, and airway hyperresponsiveness. Effective adaptation to such environmental insults is essential for the preservation of pulmonary function, whereas failure or incomplete adaptation to oxidative injury can render the host susceptible to the development of airway disease. We sought to explore the mechanisms of airway adaptation to oxidative injury. For a model to study pulmonary adaptation to oxidative stress-induced lung injury, we exposed mice to repeated nose-only chlorine gas exposures.Outcome measures were evaluated 24hours after the last chlorine exposure. Lung mechanics and airway responsiveness to methacholine were assessed by using the flexiVent. Inflammation and antioxidant responses were assessed in both bronchoalveolar lavage fluid and lung tissue. Using both loss or gain of function and genomic approaches, we further dissected the cellular and molecular mechanisms involved in pulmonary adaptation. Repeated exposures to oxidative stress resulted in pulmonary adaptation evidenced by abrogation of neutrophilic inflammation and airway hyperresponsiveness. This adaptation was independent of antioxidant mechanisms and regulatory Tcells but dependent on residential alveolar macrophages (AMs). Interestingly, 5% of AMs expressed forkhead box P3, and depletion of these cells abolished adaptation. Results from transcriptomic profiling and loss and gain of function suggest that adaptation might be dependent on TGF-β and prostaglandin E2. Pulmonary adaptation during oxidative stress-induced lung injury is mediated by a novel subset of forkhead box P3-positive AMs that limits inflammation, favoring airway adaptation and host fitness through TGF-β and prostaglandin E2.

Pulmonary toxicity following inhalation exposure to VX in anesthetized rats: Possible roles for compromised immunity and oxidative stress-induced lung injury

The nerve agent VX is one of the most deadly threat agents available in weapons stockpiles for intentional release. While mostly considered a percutaneous toxicant, it can be fatal when aerosolized. The objective of this study was to investigate toxic responses in the lung up to two weeks following a single 10-minute exposure to inhaled VX. Anesthetized rats were exposed singly and only once to VX. The nebulization rate in this system was 0.2–0.3 ml per minute with the delivery of a consistent particle size of 2.1 µm. Following exposure, all rats were removed from the ventilator and allowed to recover in the glovebox for 10–15 minutes. Results showed that inhaled VX altered several respiratory parameters and caused increased lung resistance up to 6 h post-exposure (PE). There was a trending increase in SOD and xanthine oxidoreductase (XOR) activities, both of which are indicative of oxidative stress. Based on increased lung tissue p38 signaling, MAP kinase expression was activated after VX exposure. IL-6 expression was also increased at 6 h post-inhalation for the 31.6 mg/m3 exposed group. Innate survival response mechanisms in rats may be present due to increased lung tissue mRNA AChE expression 6 h after exposure. Immunohistochemistry showed reduced staining for surfactant D and increased expression of iNOS, indicating that the activation of •NO precursor pathways. Bronchoalveloar lavage fluid (BALF) results from 1 h to 2 weeks PE show that inflammatory cells are highly active as evidenced by the increased production of cytokines and chemokines. This is the first study linking VX-induced lung injury to a possible innate survival amplification of AChE and possibly compromised immune function. These results could supplement medical treatment strategies with regard to therapeutic approaches against VX inhalational challenge.

Beneficial effects of nontoxic ozone on H2O2-induced stress and inflammation.

In this study, the anti-oxidant and anti-inflammatory efficacy of ozone oxidative preconditioning (OOP) were investigated on hydrogen peroxide (H2O2)-induced human lung alveolar cells. In MTT and trypan blue viability tests, while 100 μmol/L H2O2 caused a 17.3% and 21.9% decrease in the number of living cells, respectively, ozone at 20 μmol/L regenerated cell proliferation and prevented 9.6% and 11.0% of cell loss, respectively. In addition, H2O2 decreased the transcription levels of catalase (CAT), glutathione peroxidase (GPx), and superoxide dismutase (SOD) 5.43-, 2.89-, and 5.33-fold, respectively, while it increased Bax, NF-κβ, TNF-α, and iNOS expression 1.57-, 1.32-, 1.40-, and 1.41-fold, respectively. Ozone pretreatment, however, increased CAT, GPx, and SOD transcription levels 7.08-, 5.17-, and 6.49-fold and decreased Bax, NF-κβ, TNF-α, and iNOS transcriptions by 1.25-, 0.76-, 3.63-, and 7.91-fold, respectively. Moreover, intracellular glutathione (GSH) level and SOD activity were decreased by 46.2% and 45.0% in the H2O2 treatment group, and OOP recovered 58.5% and 20.1% of the decreases caused by H2O2. H2O2 also increased nitrite levels 7.84-fold, and OOP reduced this increase by half. Consequently, OOP demonstrated potent anti-oxidant and anti-inflammatory effects on in vitro model of oxidative stress-induced lung injury.

Therapeutic potential of soluble guanylate cyclase modulators in neonatal chronic lung disease.

Supplemental oxygen after premature birth results in aberrant airway, alveolar, and pulmonary vascular development with an increased risk for bronchopulmonary dysplasia, and development of wheeze and asthma, pulmonary hypertension, and chronic obstructive pulmonary disease in survivors. Although stimulation of the nitric oxide (NO)-soluble guanylate cyclase (sGC)-cGMP signal transduction pathway has significant beneficial effects on disease development in animal models, so far this could not be translated to the clinic. Oxidative stress reduces the NO-sGC-cGMP pathway by oxidizing heme-bound sGC, resulting in inactivation or degradation of sGC. Reduced sGC activity and/or expression is associated with pathology due to premature birth, oxidative stress-induced lung injury, including impaired alveolar maturation, smooth muscle cell (SMC) proliferation and contraction, impaired airway relaxation and vasodilation, inflammation, pulmonary hypertension, right ventricular hypertrophy, and an aggravated response toward hyperoxia-induced neonatal lung injury. Recently, Britt et al. (10) demonstrated that histamine-induced Ca(2+) responses were significantly elevated in hyperoxia-exposed fetal human airway SMCs compared with normoxic controls and that this hyperoxia-induced increase in the response was strongly reduced by NO-independent stimulation and activation of sGC. These recent studies highlight the therapeutic potential of sGC modulators in the treatment of preterm infants for respiratory distress with supplemental oxygen. Such treatment is aimed at improving aberrant alveolar and vascular development of the neonatal lung and preventing the development of wheezing and asthma in survivors of premature birth. In addition, these studies highlight the suitability of fetal human airway SMCs as a translational model for pathological airway changes in the neonate.

Antioxidant defense of peroxiredoxin 6 in lung: recent progress

Alveolar epithelial apoptosis and injury induced by oxidative stress in pulmonary diseases have drawn great attention from researchers.Peroxiredoxin 6(Prdx6),endowed with the activities of both glutathione(GSH)peroxidase and phospholipase A2(PLA2),can effectively fight against oxidative stress and alleviate oxidative stress-induced lung injury,and therefore plays an important role in pulmonary diseases.This review focuses on the structure,function,distribution and expression regulation of Prdx6,and summarizes the role of Prdx6 in pulmonary antioxidant defense and its regulatory mechanism based on experimental studies.

Effect of Diallyl Sulfide on in Vitro and in Vivo Nrf2-Mediated Pulmonic Antioxidant Enzyme Expression via Activation ERK/p38 Signaling Pathway

Increasing oxidative stress is intimately involved in the pathogenesis of lung failure. Nuclear factor-erythroid 2 related factor 2 (Nrf2) is a key element in redox homeostasis. Nrf2 regulates antioxidant-associated genes that are often the target of phytochemicals in chemoprevention. This study evaluated the effect of diallyl sulfide (DAS), which is present in garlic, on the expression of antioxidant enzymes in the rat lung and the Nrf2 modulation in MRC-5 lung cells. DAS increased the activities of glutathione S-transferase, glutathione reductase, and catalase as well as the GSH/GSSG ratio compared with the lung of untreated control rats (p < 0.05). The pulmonic superoxide dismutase, glutathione peroxidase, NAD(P)H:quinone oxidoreductase 1, and catalase mRNA levels were also significantly increased (p < 0.05) after DAS treatment. Following DAS treatment, DAS level was measured in the plasma after 7 days of oral administration, and the C(max) value was 15 ± 4.2 μM. The total amount of pulmonic Nrf2 and the nuclear translocation of Nrf2 were elevated in DAS-treated rats, clarifying the effect of DAS on the modulation of antioxidant enzymes. Furthermore, DAS could induce nuclear translocation of Nrf2 via ERK/p38 signaling pathway in lung MRC-5 cells. This study demonstrates that DAS administration can significantly induce the activity of antioxidant enzymes in rat lungs and suggests a possible use for DAS as a dietary preventive agent against oxidative stress-induced lung injury.

A Study on the Mechanism of Immunomodulating Effects of Moxifloxacin in Oleic Acid-Induced Acute Lung Injury

Background: It was hypothesized that the immunomodulating effects of moxifloxacin contribute to ameliorate oleic acid (OA)-induced acute lung injury (ALI) by suppression of cytosolic phospholipase A2 (cPLA2). This was based on observations from experiments on rats associated with neutrophilic respiratory burst, cPLA2 activity, and expressions of cPLA2, , and COX-II in the lung. Methods: ALI was induced by intravenous injection of OA in male Sprague-Dawley rats. Five hours after OA injection, protein content in bronchoalveolar lavage (BAL), lung myeloperoxidase (MPO) activity, and numbers of BAL neutrophils were measured. As an index of oxidative stress-induced lung injury, the content of malondialdehyde (MDA) in lung tissues was also determined. Lung histology, immunohistochemistry and determination of activity of cPLA2 in lung tissues were carried out. In addition, Western blotting of and COX-II in lung tissues was performed. Results: The accumulation of neutrophils in the lungs was observed after OA injection. BAL protein was increased along with neutrophilic infiltration and migration by OA. Moxifloxacin decreased all of these parameters of ALI and ameliorated ALI histologically. The increased malondialdehyde (MDA) in the lung by OA was also decreased by moxifloxacin. Moxifloxacin not only suppressed cPLA2 expression in the lungs and neutrophils but also decreased cPLA2 activity in lung tissues of rats given OA. The enhanced expressions of and COX-2 in the lung tissues of rats given OA were also suppressed by moxifloxacin. Conclusion: Moxifloxacin inhibited cPLA2 and down-regulated and COX-2 in the lungs of rats given OA, which resulted in the attenuation of inflammatory lung injury.

NADPH Oxidase-1 Plays a Crucial Role in Hyperoxia-induced Acute Lung Injury in Mice

Hyperoxia-induced acute lung injury has been used for many years as a model of oxidative stress mimicking clinical acute lung injury and the acute respiratory distress syndrome. Excess quantities of reactive oxygen species (ROS) are responsible for oxidative stress-induced lung injury. ROS are produced by mitochondrial chain transport, but also by NADPH oxidase (NOX) family members. Although NOX1 and NOX2 are expressed in the lungs, their precise function has not been determined until now. To determine whether NOX1 and NOX2 contribute in vivo to hyperoxia-induced acute lung injury. Wild-type and NOX1- and NOX2-deficient mice, as well as primary lung epithelial and endothelial cells, were exposed to room air or 100% O(2) for 72 hours. Lung injury was significantly prevented in NOX1-deficient mice, but not in NOX2-deficient mice. Hyperoxia-dependent ROS production was strongly reduced in lung sections, in isolated epithelial type II cells, and lung endothelial cells from NOX1-deficient mice. Concomitantly, lung cell death in situ and in primary cells was markedly decreased in NOX1-deficient mice. In wild-type mice, hyperoxia led to phosphorylation of c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK), two mitogen-activated protein kinases involved in cell death signaling, and to caspase-3 activation. In NOX1-deficient mice, JNK phosphorylation was blunted, and ERK phosphorylation and caspase-3 activation were decreased. NOX1 is an important contributor to ROS production and cell death of the alveolocapillary barrier during hyperoxia and is an upstream actor in oxidative stress-induced acute lung injury involving JNK and ERK pathways in mice.

High in comparison with low tidal volume ventilation aggravates oxidative stress-induced lung injury

Ventilator settings influence the development and outcome of acute lung injury. This study investigates the influence of low versus high tidal volume ( V t) on oxidative stress-induced lung injury. Isolated rabbit lungs were subjected to one of three ventilation patterns ( V t–positive end-expiratory pressure, PEEP): LVZP (6 ml/kg–0 cm H 2O), HVZP (12 ml/kg–0 cm H 2O), LV5P (6 ml/kg–5 cm H 2O). These ventilation patterns allowed a comparison between low and high V t without dependence on peak inspiratory pressure (PIP). Infusion of hypochlorite (1000 nmol/min) or buffer (control) was started at t=0 min. Pulmonary artery pressure (PAP), PIP and weight were continuously recorded. Capillary filtration coefficient [ K f,c (10 −4 ml s −1 cm H 2O −1 g −1)] was gravimetrically determined (−15/30/60/90/120 min). PIP averaged 5.8±0.6/13.9±0.6/13.9±0.4 cm H 2O in the LVZP, HVZP and LV5P groups. PIP, K f,c or PAP did not change in control groups, indicating that none of the ventilation patterns caused lung injury by themselves. Hypochlorite-induced increase in K f,c but not hypochlorite-induced increase in PAP, was significantly attenuated in the LVZP-/LV5P- versus the HVZP-group ( K f,c,max. 1.0±0.23/1.4±0.40 versus 3.2±1.0*). Experiments with hypochlorite were terminated due to excessive edema (>50 g) at 97±2.2/94.5±4.5 min in the LVZP-/LV5P-group versus 82±3.8* min in the HVZP-group (*: P<0.05). Low V t attenuated oxidative stress-induced increase in vascular permeability independently from PIP and PEEP.

Influence of cyclooxygenase and lipoxygenase inhibitors on oxidative stress-induced lung injury.

Hypochlorous acid (HOCl) is the main oxidant of activated neutrophil granulocytes. It is generated by their myeloperoxidase during respiratory burst. This study investigates the effects of HOCl on vascular permeability and pulmonary artery pressure (PAP) and characterizes the influence of the cyclooxygenase inhibitor acetylsalicylic acid (ASA) and the 5-lipoxygenase inhibitor caffeic acid (CaA) on the observed alterations. Prospective experimental study using isolated perfused rabbit lungs. Experimental laboratory in a university teaching hospital. HOCl was infused into the perfusate containing either no inhibitors, ASA (500 micromol/L), or CaA (1 micromol/L). PAP, pulmonary venous pressure, and ventilation pressure as well as lung weight gain were continuously recorded. Capillary filtration coefficient [Kf,c (10(-4) cm3 x sec(-1) x cm H2O(-1) x g(-1)]) was calculated before and 30, 60, and 90 mins after start of HOCl application. Continuous HOCl application (500, 1000, and 2000 nmol/min) resulted in a time- and dose-dependent increase in Kf,c and PAP with a threshold dose at 500 nmol/min. The onset of these changes was inversely related to the HOCl dose used. Both inhibitors, CaA and ASA, exhibited protective effects on the HOCl-induced alterations in pulmonary microcirculation. ASA predominantly reduced the HOCl-induced pressure response and had a minor but also significant inhibitory effect on edema formation as measured by Kf,c and fluid retention. CaA reduced significantly the rise in Kf,c and subsequent edema formation without effects on pulmonary pressure response. Cyclooxygenase and 5-lipoxygenase are involved in oxidative stress induced acute lung injury, suggesting a link between neutrophil-derived oxidative stress and endothelial eicosanoid metabolism.

Pulmonary effects of inhaled ultrafine particles.

Recent epidemiological studies have shown an association between increased particulate urban air pollution and adverse health effects on susceptible parts of the population, in particular the elderly with pre-existing respiratory and cardiovascular diseases. Urban particles consist of three modes: ultrafine particles, accumulation mode particles (which together form the fine particle mode) and coarse mode particles. Ultrafine particles (those of < 0.1 micron diameter) contribute very little to the overall mass, but are very high in number, which in episodic events can reach several hundred thousand/cm3 in the urban air. The hypothesis that ultrafine particles are causally involved in adverse responses seen in sensitive humans is based on several studies summarized in this brief review. Studies on rodents demonstrate that ultrafine particles administered to the lung cause a greater inflammatory response than do larger particles, per given mass. Surface properties (surface chemistry) appear to play an important role in ultrafine particle toxicity. Contributing to the effects of ultrafine particles is their very high size-specific deposition when inhaled as singlet ultrafine particles rather than as aggregated particles. It appears also that ultrafine particles, after deposition in the lung, largely escape alveolar macrophage surveillance and gain access to the pulmonary interstitium. Inhaled low doses of carbonaceous ultrafine particles can cause mild pulmonary inflammation in rodents after exposure for 6 h. Old age and a compromised/sensitized respiratory tract in rodents can increase their susceptibility to the inflammatory effects of ultrafine particles significantly, and it appears that the aged organism is at a higher risk of oxidative stress induced lung injury from these particles, compared with the young organism. Results also show that ultrafine particle effects can be significantly enhanced by a gaseous co-pollutant such as ozone. The studies performed so far support the ultrafine particle hypothesis. Additional studies are necessary to evaluate mechanistic pathways of responses.