Lipid peroxidation and glutathione peroxidase activity in chronic obstructive pulmonary disease exacerbation: prognostic value of malondialdehyde

Malondialdehyde in dried blood spots: a biomarker of systemic lipid peroxidation linked to cardiopulmonary symptoms and risk factors

Background

There are few oxidative biomarkers that can be used in resource-limited settings (e.g., rural Africa) where blood collection facilities are lacking. This study aims to evaluate the potential of malondialdehyde (MDA) in dried blood spots (DBS) as a useful biomarker to monitor cardiopulmonary health.

Methods

We first conducted a cross-validation comparison of matched capillary DBS, plasma, and whole venous blood collected from nine healthy volunteers for the measurement of total MDA (free + conjugated) and C-reactive protein (CRP), a well-established biomarker of systemic inflammation. Then a field study was conducted in a rural Senegal with a population of 441 women routinely exposed to severe household air pollution, examining associations of MDA and CRP levels in 882 DBS with self-reported cardiopulmonary symptoms.

Results

In the cross-validation study, CRP levels were strongly correlated across DBS, plasma, and whole blood. MDA levels were correlated between DBS and whole blood and were 1–2 orders of magnitude lower in plasma, suggesting that DBS MDA may reflect total oxidation levels in intracellular and extracellular compartments. In the field study, we observed significantly higher MDA levels in women with secondhand smoke exposure. An interquartile range increase in MDA concentration was associated with 27.0% (95% CI: 3.1–56.5%) and 21.1% (95% CI: −3.5% to 52.0%) increases in the incidence of chest tightness and breath difficulty, respectively. In contrast, CRP levels were not associated with worse outcomes or risk factors.

Conclusions

These results support the use of DBS as a convenient alternative to venous blood when MDA is measured as a biomarker for cardiopulmonary health risk.

Inhaled RNA Therapeutics for Obstructive Airway Diseases: Recent Advances and Future Prospects

Obstructive airway diseases, e.g., chronic obstructive pulmonary disease (COPD) and asthma, represent leading causes of morbidity and mortality worldwide. However, the efficacy of currently available inhaled therapeutics is not sufficient for arresting disease progression and decreasing mortality, hence providing an urgent need for development of novel therapeutics. Local delivery to the airways via inhalation is promising for novel drugs, because it allows for delivery directly to the target site of action and minimizes systemic drug exposure. In addition, novel drug modalities like RNA therapeutics provide entirely new opportunities for highly specific treatment of airway diseases. Here, we review state of the art of conventional inhaled drugs used for the treatment of COPD and asthma with focus on quality attributes of inhaled medicines, and we outline the therapeutic potential and safety of novel drugs. Subsequently, we present recent advances in manufacturing of thermostable solid dosage forms for pulmonary administration, important quality attributes of inhalable dry powder formulations, and obstacles for the translation of inhalable solid dosage forms to the clinic. Delivery challenges for inhaled RNA therapeutics and delivery technologies used to overcome them are also discussed. Finally, we present future prospects of novel inhaled RNA-based therapeutics for treatment of obstructive airways diseases, and highlight major knowledge gaps, which require further investigation to advance RNA-based medicine towards the bedside.

Novel drug delivery systems targeting oxidative stress in chronic obstructive pulmonary disease: a review

Oxidative stress is significantly involved in the pathogenesis and progression of chronic obstructive pulmonary disease (COPD). Combining antioxidant drugs or nutrients results in a noteworthy therapeutic value in animal models of COPD. However, the benefits have not been reproduced in clinical applications, this may be attributed to the limited absorption, concentration, and half-life of exogenous antioxidants. Therefore, novel drug delivery systems to combat oxidative stress in COPD are needed. This review presents a brief insight into the current knowledge on the role of oxidative stress and highlights the recent trends in novel drug delivery carriers that could aid in combating oxidative stress in COPD. The introduction of nanotechnology has enabled researchers to overcome several problems and improve the pharmacokinetics and bioavailability of drugs. Large porous microparticles, and porous nanoparticle-encapsulated microparticles are the most promising carriers for achieving effective pulmonary deposition of inhaled medication and obtaining controlled drug release. However, translating drug delivery systems for administration in pulmonary clinical settings is still in its initial phases.

Oxidant-antioxidant balance in the blood of patients with chronic obstructive pulmonary disease after smoking cessation

The effect of smoking cessation on the oxidative stress in patients with chronic obstructive pulmonary disease (COPD) was assessed. We recruited 73 smokers with COPD (study group), whose blood was analysed before smoking cessation, after the 1st, 2nd, and 3rd months of abstinence, 35 healthy nonsmokers (Control I), and 35 smokers with COPD (Control II). Blood was taken once in Control I and 4 times (every month) in Control II. In the study group conjugated dienes (CDs) level in plasma and erythrocytes before smoking cessation was 3 and 6.5 times higher than in Control I, respectively (P < 0.001), while thiobarbituric acid-reactive substances (TBARS) level was 89% (P < 0.001) and 51% higher (P < 0.01), respectively. Superoxide dismutase (SOD) activity was 40% higher (P < 0.05) while glutathione peroxidase (GPx) was 41% lower (P < 0.001) than in Control I. In Control II, the similar differences as compared to Control I were observed throughout the study. Smoking cessation resulted in decrease of CDs, TBARS, and SOD and GPx increase, with no changes in catalase and vitamins A and E. COPD is accompanied by oxidative stress. A three-month tobacco abstinence facilitated restoring the oxidant-antioxidant balance systemically, but it did not affect spirometric parameters.

Oxidative stress in COPD and its measurement through exhaled breath condensate

Oxidative stress and airway inflammation together form a vicious cycle, which is responsible for the disease progression in chronic pulmonary obstructive disease (COPD). The damaging effects of oxidative stress accumulate over the years, causing increased bronchial hyperresponsiveness and inflammation and destruction of airway epithelial cells and impairing the functions of antiproteases and surfactant. Although the lung expresses a number of antioxidants, cigarette smoking and recurrent infections associated with this disease overwhelm this protective mechanism. Studies of antioxidants in COPD have yielded conflicting results, probably due to the compartmentalization of these mediators, and because of the fact that the lung is a difficult organ to sample. Chronic exposure to oxidants upregulates the production of antioxidants, which become depleted during acute exacerbations. Future studies of the pathogenesis of COPD require a noninvasive yet accurate sampling procedure, of which exhaled breath condensate (EBC) is a good candidate. EBC samples the epithelial lining fluid, which contains the local oxidative stress markers in the lung. Oxidative stress markers such as hydrogen ions, hydrogen peroxide, 8-isoprostanes, thiobarbituric acid reactive products, nitrosothiols, and nitrite/nitrate have been identified in EBC of COPD patients, whereas many other markers of the oxidative-antioxidative balance have yet to be investigated.

Melatonin levels and enzymatic antioxidant defense system decrease in blood of patients with bronchial asthma

The etiology of bronchial asthma (BA) is not clearly understood. In recent years, a few studies have investigated the possible role of reactive oxygen species (ROS) in the etiology of BA. There are some defense mechanisms in the organism to avoid the harmful effects of ROS. Melatonin (MEL) is synthesized by the pineal gland at night and exhibits antioxidant properties. The aim of this study was to investigate serum MEL levels, erythrocyte antioxidant enzyme activities, namely superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and the association of the respiratory function tests, namely dynamic lung volumes; the forced vital capacity (FVC/L, FVC%), the forced expiratory volume in 1 s (FEV(1)/L, FEV(1)%), and peak expiratory flow (PEF/L/s, PEF%) in 30 patients with BA and 30 age-matched healthy controls. The levels of serum MEL, the activities of erythrocyte SOD, and the values of FVC/L, FVC%, FEV(1)/L, and FEV(1)% were significantly lower in the patients with BA than in control group. The positive correlations were observed between FVC% with erythrocyte SOD and GSH-Px, FEV(1)/L as well as FEV(1)% with erythrocyte SOD, whereas negative correlation was observed between PEF/L/s with levels of serum MEL. In conclusion, these results provide some evidence for a potential role of decreased antioxidant enzymes, MEL, and respiratory function test values in BA.

Antioxidant enzymes and melatonin levels in patients with bronchial asthma and chronic obstructive pulmonary disease during stable and exacerbation periods

An imbalance between oxidative stress and antioxidative capacity may play an important role in the development and progression of bronchial asthma (BA) and chronic obstructive pulmonary disease (COPD). We carried out a study to assess the systemic oxidant-antioxidant status during the exacerbation and the stable period in patients with BA and COPD. A total of 33 patients, 16 with BA and 17 with COPD were included in the study. During the exacerbation and the stable periods, levels of malondialdehyde (MDA), activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), glutathione reductase (GRd), and catalase (CAT) in erythrocytes and serum melatonin concentrations were investigated. Blood counts, respiratory functions, and blood gases of the patients were also performed. During an exacerbation period of BA, despite the decreases in GSH-Px, GRd and melatonin levels, MDA and CAT levels, and the white blood cell count, the percentage of eosinophils were significantly higher than in the stable period. Also, it was found that FEV(1)/L (where FEV(1) is the forced expiratory volume in 1 s), FVC/L (where FVC is forced vital capacity), PEF/L/s (where PEF is peak expiratory flow), pO(2) (where pO(2) is oxygen pressure) levels increased during the stable period in patients with BA. MDA and SOD values were higher in the exacerbation period than in the stable period although GSH-Px, GRd, melatonin, pH, and pO(2) values were lower in the exacerbation period than in the stable period. The blood counts and the respiratory function tests did not change between the exacerbation and the stable period of patients with COPD significantly. In conclusion, we observed that oxidative stress in the exacerbation period of patients with BA and COPD increased whereas the antioxidant enzymes and melatonin values reduced. The episodes of BA or COPD might be associated with elevated levels of oxidative stress.

Targeting Nrf2 with the triterpenoid CDDO-imidazolide attenuates cigarette smoke-induced emphysema and cardiac dysfunction in mice

Chronic obstructive pulmonary disease (COPD), which comprises emphysema and chronic bronchitis resulting from prolonged exposure to cigarette smoke (CS), is a major public health burden with no effective treatment. Emphysema is also associated with pulmonary hypertension, which can progress to right ventricular failure, an important cause of morbidity and mortality among patients with COPD. Nuclear erythroid 2 p45 related factor-2 (Nrf2) is a redox-sensitive transcription factor that up-regulates a battery of antioxidative genes and cytoprotective enzymes that constitute the defense against oxidative stress. Recently, it has been shown that patients with advanced COPD have a decline in expression of the Nrf2 pathway in lungs, suggesting that loss of this antioxidative protective response is a key factor in the pathophysiological progression of emphysema. Furthermore, genetic disruption of Nrf2 in mice causes early-onset and severe emphysema. The present study evaluated whether the strategy of activation of Nrf2 and its downstream network of cytoprotective genes with a small molecule would attenuate CS-induced oxidative stress and emphysema. Nrf2(+/+) and Nrf2(-/-) mice were fed a diet containing the potent Nrf2 activator, 1-[2-cyano-3-,12-dioxooleana-1,9(11)-dien-28-oyl]imidazole (CDDO-Im), while being exposed to CS for 6 months. CDDO-Im significantly reduced lung oxidative stress, alveolar cell apoptosis, alveolar destruction, and pulmonary hypertension in Nrf2(+/+) mice caused by chronic exposure to CS. This protection from CS-induced emphysema depended on Nrf2, as Nrf2(-/-) mice failed to show significant reduction in alveolar cell apoptosis and alveolar destruction after treatment with CDDO-Im. These results suggest that targeting the Nrf2 pathway during the etiopathogenesis of emphysema may represent an important approach for prophylaxis against COPD.

Oxidants and the pathogenesis of lung diseases

The increasing number of population-based and epidemiologic associations between oxidant pollutant exposures and cardiopulmonary disease exacerbation, decrements in pulmonary function, and mortality underscores the important detrimental effects of oxidants on public health. Because inhaled oxidants initiate a number of pathologic processes, including inflammation of the airways, which may contribute to the pathogenesis and/or exacerbation of airways disease, it is critical to understand the mechanisms through which exogenous and endogenous oxidants interact with molecules in the cells, tissues, and epithelial lining fluid of the lung. Furthermore, it is clear that interindividual variation in response to a given exposure also exists across an individual lifetime. Because of the potential impact that oxidant exposures may have on reproductive outcomes and infant, child, and adult health, identification of the intrinsic and extrinsic factors that may influence susceptibility to oxidants remains an important issue. In this review, we discuss mechanisms of oxidant stress in the lung, the role of oxidants in lung disease pathogenesis and exacerbation (eg, asthma, chronic obstructive pulmonary disease, and acute respiratory distress syndrome), and the potential risk factors (eg, age, genetics) for enhanced susceptibility to oxidant-induced disease.

Oxidative stress in patients with COPD and pulmonary hypertension

OBJECTIVE

Oxidative stress plays an important role in the pathogenesis of chronic obstructive pulmonary disease (COPD). Oxidant/antioxidant imbalance has also been reported in various forms of pulmonary hypertension. The present study aimed to assess systemic oxidative stress, as reflected by serum malondialdehyde (MDA) concentrations and activities of antioxidant enzymes in erythrocytes [glutathione peroxidase (GPX), superoxide dismutase (SOD) and catalase (CAT)] in patients with and without pulmonary hypertension secondary to COPD.

PATIENTS AND METHODS

Seventy-five patients (58 male) with COPD (mean age 65.1 +/- 1.2 years; mean smoking history 35.6 +/- 3.8 pack-years) were studied. Twenty-one healthy non-smokers served as a control group. Pulmonary function was evaluated with body plethysmography; mean and systolic pulmonary artery pressures (Ppa) were assessed with Doppler echocardiography. Serum concentrations of MDA and activities of GPX, SOD and CAT in washed red blood cells were measured using spectrophotometry.

RESULTS

Pulmonary hypertension was present in 28 patients with COPD (systolic Ppa: 46.4 +/- 2.3 mmHg; mean Ppa: 26.0 +/- 1.9 mmHg) and absent in 47 (systolic Ppa: 22.9 +/- 0.8 mmHg; mean Ppa: 13.4 +/- 0.6 mmHg). Compared with the healthy control group, all the patients (with or without pulmonary hypertension) had higher serum MDA concentrations (1.5 +/- 0.1 versus 2.3 +/- 0.1 versus 2.3 +/- 0.1 nmol/mL, ANOVA, P < 0.001) and lower erythrocyte GPX activity (51.3 +/- 3.2 versus 42.2 +/- 2.0 versus 41.3 +/- 2.5 U/g Hb, P = 0.029), whereas SOD (1121.1 +/- 29.0 versus 1032.6 +/- 21.8 versus 1032.7 +/- 36.2 U/g Hb, P = 0.063) and CAT activities (4.9 +/- 0.2 versus 4.6 +/- 0.1 versus 4.7 +/- 0.2 U/g Hb; P= 0.454) were similar. No differences were observed in serum MDA concentrations or activities of GPX, SOD and CAT in erythrocytes between COPD patients with and without pulmonary hypertension.

CONCLUSION

The study demonstrates the presence of oxidative/antioxidative imbalance in the systemic circulation in patients with COPD: compared with healthy subjects, COPD patients had higher serum MDA concentrations and lower GPX activity in erythrocytes. The magnitudes of the increase in MDA and reduction in GPX activity were similar in COPD patients with pulmonary hypertension and in those with normal pulmonary artery pressures.

Ligneous periodontitis and gingival antioxidant status: report of two cases

Ligneous periodontitis (LP) is a rare periodontal disease in which plasminogen deficiency and fibrin deposition both play a part, resulting in characteristic gingival enlargement and periodontal breakdown. Recent data suggest that oxidant/antioxidant changes are significant in the pathology of oral diseases. This study examines the gingival histopathology in 2 cases with LP. To examine the antioxidant (AO) status, the activity of the major AOs glutathione (GSH), catalase (CAT), and glutathione S-transferase (GST) and the malondialdehyde (MDA) levels, a product of lipid peroxidation, were measured and compared with healthy control subjects. The histopathologic examination of the gingiva revealed subepithelial fibrin accumulation and irregular extensive downward proliferation of the epithelium. Biochemical analysis showed that the CAT, GST, and MDA levels were higher in LP patients than in the control subjects, and the GSH level was lower. Our preliminary findings show that in LP, the AO capacity of the gingiva changes or decreases and lipid peroxidation increases, which suggests that oxidative stress is involved in the pathology of the periodontal breakdown observed in this disease.

Antibiotic Treatment of Exacerbations of COPD

BACKGROUND

Therapy with antibiotics influences recovery only in selected cases of COPD exacerbations. We evaluated the efficacy and safety of procalcitonin guidance compared to standard therapy with antibiotic prescriptions in patients experiencing exacerbations of COPD.

METHODS

A total of 208 consecutive patients requiring hospitalization for COPD exacerbation were randomized at the index exacerbation to procalcitonin-guided or standard antibiotic therapy. Patients receiving procalcitonin-guided therapy were treated with antibiotics according to serum procalcitonin levels; standard-therapy patients received antibiotics according to the attending physician. The primary outcome was the antibiotic exposure at the index exacerbation and the subsequent antibiotic requirement for COPD exacerbation within 6 months. Secondary outcomes were clinical recovery, symptom scores, length of hospitalization, ICU stay, death, lung function, exacerbation rate, and time to next exacerbation.

RESULTS

At the index exacerbation, procalcitonin guidance reduced antibiotic prescription (40% vs 72%, respectively; p < 0.0001) and antibiotic exposure (relative risk [RR], 0.56; 95% confidence interval [CI], 0.43 to 0.73; p < 0.0001) compared to standard therapy. Moreover, procalcitonin guidance at the index exacerbation allowed a significant sustained reduction in total antibiotic exposure for up to 6 months (RR, 0.76; 95% CI, 0.64 to 0.92; p = 0.004). Clinical outcome and improvement in FEV(1) at 14 days and 6 months did not differ between groups. Within 6 months, the exacerbation rate (0.62 vs 0.64, respectively), the rehospitalization rate (0.21 vs 0.24, respectively), and mean (+/- SD) time to the next exacerbation (70.0 +/- 46.1 vs 70.4 +/- 51.9 days, respectively; p = 0.523) were similar in both groups.

CONCLUSIONS

Procalcitonin guidance for exacerbations of COPD offers a sustained advantage over standard therapy in reducing antibiotic use for up to 6 months with a number-needed-to-treat of 3.

Relations of glycemic index and glycemic load with plasma oxidative stress markers

BACKGROUND

Recent data suggest that acute hyperglycemia may increase in vivo free radical production. This increased production has been implicated in many disease processes.

OBJECTIVE

The objective was to investigate whether a diet with a high glycemic index (GI) or glycemic load (GL) is associated with greater oxidative stress as measured by 2 lipid peroxidation markers, malondialdehyde (MDA) and F2-isoprostanes (IsoPs).

DESIGN

Plasma MDA and IsoP concentrations were measured in 292 healthy adults, and dietary GI and GL were assessed by using a validated food-frequency questionnaire. Cross-sectional associations between GI, GL, and the 2 markers were examined by using multiple regression techniques with adjustment for potential confounding variables.

RESULTS

Dietary GI was positively associated with both plasma MDA and IsoPs. The mean multivariate-adjusted MDA concentrations increased from 0.55 to 0.73 micromol/L as GI increased from the lowest to the highest quartile (P for trend = 0.02); the corresponding IsoP concentrations increased from 0.034 to 0.040 ng/mL (P for trend = 0.03). GL was positively associated with both MDA and IsoPs, but the linear relation was significant only for MDA. In addition, a marginally significant interaction between overall GI and body mass index (BMI; in kg/m2) for plasma MDA was observed (P = 0.09). The positive association between overall GI and MDA was stronger in those with a BMI < 26.5 than for those with a BMI > or = 26.5.

CONCLUSIONS

Chronic consumption of high-GI foods may lead to chronically high oxidative stress. A low-GI diet, not a low-carbohydrate diet, appears to be beneficial in reducing oxidative stress.

Os radicais livres de oxigênio e as doenças pulmonares

Os radicais livres de oxigênio são moléculas que apresentam elétrons não pareados em sua órbita externa, capazes de transformar outras moléculas com as quais se encontram, como proteínas, carbohidratos, lípides e o ácido desoxirribonucleico. Essas moléculas são geradas em situações clínicas onde microambientes de hipóxia são seguidos por microambientes de reoxigenação. Nesse grupo estão o choque hemodinâmico, a septicemia, a resposta inflamatória sistêmica, as hepatites fulminantes, o transplante de órgãos, e a insuficiência respiratória, entre outras condições. Neste trabalho discutimos os principais conceitos sobre os radicais livres de oxigênio: os principais tipos, sua formação e a forma como atuam sobre todas as estruturas celulares provocando lesão tecidual significativa. Os principais sistemas de defesa antioxidante existentes para combater o estresse oxidativo são comentados, com destaque para a glutationa, superóxido dismutase, catalase, glutationa peroxidase e N-acetilcisteína. A influência dos radicais livres de oxigênio sobre as principais doenças pulmonares também é discutida, com ênfase nos produtos do cigarro, doença pulmonar obstrutiva crônica, asma, apnéia obstrutiva do sono e síndrome do desconforto respiratório agudo.

The effects of antioxidants on exercise-induced lipid peroxidation in patients with COPD

OBJECTIVE

The oxidant-antioxidant balance plays an important role in the pathogenesis of COPD. The aim of the present study was to evaluate the effects of exercise, as an oxidative stress factor on the oxidant-antioxidant balance and to investigate whether short-term antioxidant treatment affects lipid peroxidation products.

METHODOLOGY

Twenty-one stable COPD patients and 10 control subjects were included in the study. Symptom-limited exercise tests were performed by all subjects. Blood was collected before and 1 h after exercise in control subjects and before, 1 and 3 h after exercise in COPD patients, for analysis of malondialdehyde (MDA), reduced glutathione (GSH) and vitamin E (VE) levels. VE and vitamin C treatments were added to the regular bronchodilator therapy in 10 COPD patients for 1 month. After the treatment period, an exercise test was performed and blood was collected again for MDA, GSH and VE levels.

RESULTS

Baseline GSH and VE levels were significantly lower in the COPD group when compared with the control subjects. There was no statistically significant difference in MDA levels between the two groups. In the COPD group, MDA levels 3 h after exercise were significantly higher than at baseline. In contrast there were no significant differences in MDA, VE and GSH levels in the control group after exercise. VE and MDA levels increased significantly after exercise in COPD patients but there was no difference in GSH levels. Baseline exercise time was significantly lower in the COPD group than in the controls. In 10 COPD patients who were given antioxidant therapy, their exercise time increased significantly and there was no increase in MDA and VE levels after the repeated exercise test.

CONCLUSIONS

Antioxidant levels were significantly lower in COPD patients than in control subjects. In these patients, exercise results in more significant oxidative stress and lipid peroxidation than in control subjects and antioxidant therapy may decrease lipid peroxidation following exercise and improve exercise capacity.

The role of oxidative stress in chronic obstructive pulmonary disease

Tobacco smoke is the number one risk factor for chronic obstructive pulmonary disease (COPD) and contains a high concentration of oxidants. The lung has a high concentration of antioxidants and antioxidant enzymes; however, COPD patients show evidence of increased oxidative stress suggesting that endogenous antioxidants may be insufficient to prevent oxidative damage from cigarette smoke. The consequences of increased oxidative stress in the lung include increased transcription of inflammatory genes, increased protease activity, and increased mucus secretion. Oxidative stress is often associated with impaired skeletal muscle function and may be one of the causes of glucocorticoid resistance. While current pharmacologic approaches to the treatment of chronic obstructive pulmonary disease do not commonly include antioxidants, preclinical studies involving animal models suggest that antioxidant superoxide dismutase mimetics offer a potential new therapeutic approach to the prevention and treatment of chronic obstructive pulmonary disease.