The relationship between chronic hypoxemia and activation of the tumor necrosis factor-alpha system in patients with chronic obstructive pulmonary disease

Inflammatory cells and apoptosis in respiratory and limb muscles of patients with COPD

Discrepancies exist regarding the involvement of cellular inflammation and apoptosis in the muscle dysfunction of chronic obstructive pulmonary disease (COPD) patients with preserved body composition. We explored whether levels of inflammatory cells and apoptosis were increased in both respiratory and limb muscles of COPD patients without nutritional abnormalities. In the vastus lateralis, external intercostals, and diaphragms of severe and moderate COPD patients with normal body composition, and in healthy subjects, intramuscular leukocytes and macrophage levels were determined (immunohistochemistry). Muscle structure was also evaluated. In the diaphragm and vastus lateralis of severe and moderate COPD patients and controls, apoptotic nuclei were explored using the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay, electron microscopy, and caspase-3 expression. In COPD patients compared with controls, diaphragm and intercostal levels of inflammatory cells were extremely low and not significantly different. However, in the vastus lateralis of the severe patients, inflammatory cell counts, although also very low, were significantly greater. In those patients, TUNEL-positive nuclei levels were also significantly greater in diaphragms and vastus lateralis. A significant inverse relationship was found between quadriceps TUNEL-positive nuclei levels and muscle force. Ultrastructural apoptotic nuclei revealed no differences in respiratory or limb muscles between COPD patients and controls. Muscle caspase-3 expression did not differ between patients and controls. In severe COPD patients with preserved body composition, while increased apoptotic nuclei seems to be a contributor to their muscle dysfunction, cellular inflammation does not. The increased numbers of TUNEL-positive nuclei in their muscles suggest that they may also be exposed to a continuous repair/remodeling process.

Respiratory and skeletal muscle strength in chronic obstructive pulmonary disease: impact on exercise capacity and lower extremity function

PURPOSE

We sought to quantify the impact of respiratory muscle and lower extremity strength on exercise capacity and lower extremity function (LEF) in patients with chronic obstructive pulmonary disease (COPD).

METHODS

In 828 persons with COPD, we assessed the impact of reduced respiratory (maximum inspiratory pressure, MIP) and lower extremity muscle strength (quadriceps strength, QS) on exercise capacity (6-minute walk test, 6MWT), and LEF (short physical performance battery). Multiple regression analyses taking into account key covariates, including lung function and smoking, tested the associations between muscle strength and exercise and functional capacity.

RESULTS

For each 0.5 SD decrement in QS, men walked 18.3 m less during 6MWT (95% confidence interval [CI], -24.1 to -12.4); women 25.1 m less (95% CI, -31.1 to -12.4). For each 0.5 SD decrement in MIP, men walked 9.4 m less during 6MWT (95% CI, -15.2 to -3.6); women 8.7 m less (95% CI, -14.1 to -3.4). For each 0.5 SD decrease in QS, men had a 1.32 higher odds (95% CI, 1.11-1.15) of poor LEF; women had a 1.87 higher odds (95% CI, 1.54-2.27). Lower MIP (per 0.5 SD) was associated with increased odds of poor LEF in women (odds ratio = 1.18; 95% CI, 1.00-1.39), but not in men (odds ratio = 1.10; 95% CI, 0.93-1.31).

CONCLUSIONS

In COPD, reduced respiratory and lower extremity muscle strength are associated with decreased exercise and functional capacity. Muscle weakness is likely an important component of impairment and disability in patients with COPD.

Association of osteopontin and tumor necrosis factor-α levels with insulin resistance in obese patients with obstructive sleep apnea syndrome

OBJECTIVE

The aims of this study were to compare the tumor necrosis factor (TNF)-α and osteopontin levels, to identify the relationship between insulin resistance (IR) and osteopontin levels in obese patients with and without obstructive sleep apnea syndrome (OSAS).

METHOD

The study population included 62 obese patients (35 males, 27 females) with OSAS and was compared with 26 obese patients (16 males, 10 females) without OSAS as a control group. Polysomnographic evaluation, spirometric tests and arterial blood gas sampling were performed on the obese patients with OSAS. Plasma levels of TNF-α and osteopontin were measured by enzyme-linked immunosorbent assays during the process. IR was estimated using the homeostasis model assessment (HOMA).

RESULTS

Mean plasma levels of fasting glucose, insulin, HOMA, liver function test, hematocrit, leukocyte, TSH, free T4, fibrinogen, TNF-α, and osteopontin were similar in the 2 groups. In patients with OSAS, mean osteopontin levels were positively correlated with mean fasting insulin levels (r=0.306, p=0.01), HOMA (r=0.299, p=0.01), apnea-hypopnea index (r=0.377, p=0.03) and Epworth Sleepiness Scale (r=0.299, p=0.01). However, mean TNF-α levels were negatively correlated with Epworth Sleepiness Scale (r=-0.298, p=0.01) in the patients with OSAS.

CONCLUSIONS

It was observed that TNF-α and osteopontin levels showed no difference between obese patients with and without OSAS. However, osteopontin levels increased with fasting insulin, IR, OSAS severity, and daytime sleepiness.

Obstructive sleep apnea in chronic obstructive pulmonary disease patients

PURPOSE OF REVIEW

Chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea (OSA) represent two of the most prevalent chronic respiratory disorders and cardiovascular diseases are major co-morbidities in both. Co-existence of both disorders (overlap syndrome) occurs in 1% of adults and overlap patients have worse nocturnal hypoxemia and hypercapnia than COPD and OSA patients alone. The present review discusses recent data concerning the pathophysiological and clinical significance of the overlap syndrome.

RECENT FINDINGS

The severity of obstructive ventilatory impairment and hyperinflation, especially the inspiratory capacity to total lung capacity (TLC) ratio, correlates with the severity of sleep-related breathing disturbances. Early treatment with continuous positive airway pressure (CPAP) improves survival, reduces hospitalization and pulmonary hypertension, and also reduces hypoxemia. Evidence of systemic inflammation and oxidative stress in COPD and sleep apnea provides insight into potential interactions between both disorders that may predispose to cardiovascular disease. Long-term outcome studies of overlap patients currently underway should provide further evidence of the clinical significance of the overlap syndrome.

SUMMARY

Studies of overlap syndrome patients at a clinical, physiological and molecular level should provide insight into disease mechanisms and consequences of COPD and sleep apnea, in addition to identifying potential relationships with cardiovascular disease.

Hypoxemia in patients with COPD: cause, effects, and disease progression

Chronic obstructive pulmonary disease (COPD) is a leading cause of death and disability internationally. Alveolar hypoxia and consequent hypoxemia increase in prevalence as disease severity increases. Ventilation/perfusion mismatch resulting from progressive airflow limitation and emphysema is the key driver of this hypoxia, which may be exacerbated by sleep and exercise. Uncorrected chronic hypoxemia is associated with the development of adverse sequelae of COPD, including pulmonary hypertension, secondary polycythemia, systemic inflammation, and skeletal muscle dysfunction. A combination of these factors leads to diminished quality of life, reduced exercise tolerance, increased risk of cardiovascular morbidity, and greater risk of death. Concomitant sleep-disordered breathing may place a small but significant subset of COPD patients at increased risk of these complications. Long-term oxygen therapy has been shown to improve pulmonary hemodynamics, reduce erythrocytosis, and improve survival in selected patients with severe hypoxemic respiratory failure. However, the optimal treatment for patients with exertional oxyhemoglobin desaturation, isolated nocturnal hypoxemia, or mild-to-moderate resting daytime hypoxemia remains uncertain.

C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) as inflammation markers in elderly patients with stable chronic obstructive pulmonary disease (COPD)

Erythrocyte sedimentation rate (ESR) might represent a less expensive alternative to C-reactive protein (CRP) as a marker of systemic inflammation in stable chronic obstructive pulmonary disease (COPD). We tried to verify this hypothesis in 223 consecutive outpatients aged 65 years or more with stable COPD enrolled in a multicenter observational study. Patients were grouped according to normal/increased ESR/CRP values and groups were compared with regard to clinical and laboratory characteristics. Correlations between CRP, ESR and selected variables of interest were assessed by Spearman's ζ-test and multivariate linear regression analysis. CRP was weakly and inversely correlated with the forced expiratory volume in the first second (FEV1%) (Spearman's ζ = -0.15; p < 0.027), while ESR was not (Spearman's ζ = -0.05; p = 0.411). The highest prevalence of anemia and hypoalbuminemia and the lowest FEV1% were recorded in high ESR-high CRP group. For anemia B = 14.180 ± 3.521 (± S.E.M.); p = 0.001 and hypoalbuminemia B = 10.241 ± 3.790; p = 0.007 qualified as significant independent correlates of ESR values, while only FEV1 remained significantly associated with CRP values (B = -0.570 ± 0.258; p = 0.028). In conclusion, CRP, but not ESR, shows a weak correlation with COPD severity, while anemia and hypoalbuminemia are main correlates of high ESR. Neither ESR, nor CRP qualify as reliable markers of COPD severity and seem to reflect the effects of different determinants.

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.

Skeletal microstructural abnormalities in postmenopausal women with chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is associated with osteoporosis and fragility fractures. The objectives of this study were to assess static and dynamic indices of cancellous and cortical bone structure in postmenopausal women with COPD. Twenty women with COPD who had not received chronic oral glucocorticoids underwent bone biopsies after double tetracycline labeling. Biopsies were analyzed by histomorphometry and µCT and compared with age-matched controls. Distribution of the patients according to the Global Initiative for Chronic Obstructive Lung Disease (GOLD) was: Type I (15%), Type II (40%), Type III (30%), and Type IV (15%). Mean (±SD) cancellous bone volume (15.20 ± 5.91 versus 21.34 ± 5.53%, p = .01), trabecular number (1.31 ± 0.26 versus 1.77 ± 0.51/mm, p = .003), and trabecular thickness (141 ± 23 versus 174 ± 36 µm, p = .006) were lower in patients than in controls. Connectivity density was lower in COPD (5.56 ± 2.78 versus 7.94 ± 3.08/mm, p = .04), and correlated negatively with smoking (r = -0.67; p = .0005). Trabecular separation (785 ± 183 versus 614 ± 36 µm, p = .01) and cortical porosity (4.11 ± 1.02 versus 2.32 ± 0.94 voids/mm(2); p < .0001) were higher in COPD while cortical width (458 ± 214 versus 762 ± 240 µm; p < .0001) was lower. Dynamic parameters showed significantly lower mineral apposition rate in COPD (0.56 ± 0.16 versus 0.66 ± 0.12 µm/day; p = .01). Patients with more severe disease, GOLD III and IV, presented lower bone formation rate than GOLD I and II (0.028 ± 0.009 versus 0.016+ 0.011 µm(3)/µm(2)/day; p = 04). This is the first evaluation of bone microstructure and remodeling in COPD. The skeletal abnormalities seen in cancellous and cortical bone provide an explanation for the high prevalence of vertebral fractures in this disease.

Metabolic syndrome is associated with increased risk of acute exacerbation of COPD: a preliminary study

Studies have confirmed correlation between metabolic syndrome (MetS) and chronic obstructive pulmonary disease (COPD). However, to date, no studies have analyzed correlation between exacerbations of COPD (ECOPD) and MetS. The aim of this preliminary study was to examine if presence of MetS increases the frequency and duration of ECOPD. Patients with COPD were prospectively enrolled and followed between March 2008 and September 2009. Medical records, pulmonary function tests, chest X-rays; laboratory test results were gathered to establish the presence of COPD and MetS. Patients were divided in two groups; with and without MetS. The ECOPD was defined as worsening of symptoms requiring increased use of rescue medications and/or need for either systemic steroids or antibiotics or that led to emergency room visit or hospitalizations during 12 months follow-up. A total of 106 patients were recruited, 29 with MetS and 77 without. The mean exacerbation of COPD frequency was 2.4 ± 0.8 in MetS group versus 0.68 ± 0.6 in the control group during the follow-up period (P < 0.001). Mean duration of each exacerbation was 7.5 ± 1.5 days in patients with MetS versus 5 ± 2.4 days in patients without. Serum C-reactive protein (r = 0.31, P = 0.001), fasting blood glucose (r = 0.55, P < 0.001), and triglycerides (r = 0.251, P = 0.01) were positively and significantly correlated with exacerbation frequency. This study demonstrates an association between ECOPD and its duration with the MetS. The systemic inflammation induced by common cytokines may explain the linkage between the two conditions.

Systemic inflammation in chronic obstructive pulmonary disease: may adipose tissue play a role? Review of the literature and future perspectives

Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality worldwide. Low-grade systemic inflammation is considered a hallmark of COPD that potentially links COPD to increased rate of systemic manifestations of the disease. Obesity with/without the metabolic syndrome and cachexia represent two poles of metabolic abnormalities that may relate to systemic inflammation. On one hand systemic inflammatory syndrome likely reflects inflammation in the lungs, i.e. results from lung-to plasma spillover of inflammatory mediators. On the other hand, obesity-related hypoxia results in local inflammatory response within adipose tissue per se, and may contribute to elevations in circulatory mediators by spillover from the adipose tissue to the systemic compartment. The extent to which systemic hypoxia contributes to the adipose tissue inflammation remains unknown. We assume that in patients with COPD and concurrent obesity at least three factors play a role in the systemic inflammatory syndrome: the severity of pulmonary impairment, the degree of obesity-related adipose tissue hypoxia, and the severity of systemic hypoxia due to reduced pulmonary functions. The present review summarizes the epidemiological and clinical evidence linking COPD to obesity, the role of adipose tissue as an endocrine organ, and the role of hypoxia in adipose tissue inflammation.

Structural and functional changes of peripheral muscles in chronic obstructive pulmonary disease patients

PURPOSE OF REVIEW

The purpose of this review is to identify new advances in our understanding of skeletal muscle dysfunction in patients with chronic obstructive pulmonary disease (COPD).

RECENT FINDINGS

Recent studies have confirmed the relevance of muscle dysfunction as an independent prognosis factor in COPD. Animal studies have shed light on the molecular mechanisms governing skeletal muscle hypertrophy/atrophy. Recent evidence in patients with COPD highlighted the contribution of protein breakdown and mitochondrial dysfunction as pathogenic mechanisms leading to muscle dysfunction in these patients.

SUMMARY

COPD is a debilitating disease impacting negatively on health status and the functional capacity of patients. COPD goes beyond the lungs and incurs significant systemic effects among which muscle dysfunction/wasting is one of the most important. Muscle dysfunction is a prominent contributor to exercise limitation, healthcare utilization and an independent predictor of morbidity and mortality. Gaining more insight into the molecular mechanisms leading to muscle dysfunction/wasting is key for the development of new and tailored therapeutic strategies to tackle skeletal muscle dysfunction/wasting in COPD patients.

Local inflammation occurs before systemic inflammation in patients with COPD

BACKGROUND AND OBJECTIVE

COPD is associated not only with an abnormal inflammatory response in the lung but also with systemic inflammation, including systemic oxidative stress, activation of circulating inflammatory cells and increased circulating levels of inflammatory cytokines. Understanding the nature and course of systemic inflammation in COPD is important given the potential for anti-inflammatory therapy. This study explored whether local and systemic inflammation occur concurrently in patients with COPD.

METHODS

Forty-four patients with stable COPD, 10 smoking controls and 10 non-smoking controls were enrolled in this observational study. Induced sputum and peripheral blood samples were obtained simultaneously for measurement of inflammatory cell numbers and the concentrations of IL-6 and CRP.

RESULTS

The total number of cells in the sputum total cell number, percentage of neutrophils and the concentration of IL-6 were significantly higher in smoking controls and patients with COPD than in non-smoking controls (P < 0.05 and P < 0.01, respectively). As the disease stage progressed, airway inflammatory cells and IL-6 levels increased. CRP levels in sputum were significantly higher in stage II, III and IV COPD patients than in smoking and non-smoking controls (P < 0.01). However, the peripheral WCC and percentage of neutrophils were similar in patients with COPD, smoking and non-smoking controls. Circulatory concentrations of IL-6 and CRP in stages III and IV COPD patients were significantly higher than in smoking and non-smoking controls (P < 0.05 and P < 0.01, respectively). Additionally, there were positive correlations between sputum and blood IL-6 and CRP levels (r = 0.566, P < 0.01 and r = 0.443, P < 0.01, respectively).

CONCLUSIONS

The increase in the inflammatory cell population and IL-6 and CRP levels in the airway may occur earlier than in the peripheral blood, and reflect the degree of airflow limitation better than do peripheral blood measurements. Systemic inflammation may be present in patients with severe or very severe COPD.

TNF-alpha-mediated reduction in PGC-1alpha may impair skeletal muscle function after cigarette smoke exposure

Skeletal muscle dysfunction contributes to exercise limitation in COPD. In this study cigarette smoke exposure was hypothesized to increase expression of the inflammatory cytokine, TNF-alpha, thereby suppressing PGC-1alpha, and hence affecting down stream molecules that regulate oxygen transport and muscle function. Furthermore, we hypothesized that highly vascularized oxidative skeletal muscle would be more susceptible to cigarette smoke than less well-vascularized glycolytic muscle. To test these hypotheses, mice were exposed to cigarette smoke daily for 8 or 16 weeks, resulting in 157% (8 weeks) and 174% (16 weeks) increases in serum TNF-alpha. Separately, TNF-alpha administered to C2C12 myoblasts was found to dose-dependently reduce PGC-1alpha mRNA. In the smoke-exposed mice, PGC-1alpha mRNA was decreased, by 48% in soleus and 23% in EDL. The vascular PGC-1alpha target molecule, VEGF, was also down-regulated, but only in the soleus, which exhibited capillary regression and an oxidative to glycolytic fiber type transition. The apoptosis PGC-1alpha target genes, atrogin-1 and MuRF1, were up-regulated, and to a greater extent in the soleus than EDL. Citrate synthase (soleus-19%, EDL-17%) and beta-hydroxyacyl CoA dehydrogenase (beta-HAD) (soleus-22%, EDL-19%) decreased similarly in both muscle types. There was loss of body and gastrocnemius complex mass, with rapid soleus but not EDL fatigue and diminished exercise endurance. These data suggest that in response to smoke exposure, TNF-alpha-mediated down-regulation of PGC-1alpha may be a key step leading to vascular and myocyte dysfunction, effects that are more evident in oxidative than glycolytic skeletal muscles.

O papel do estresse oxidativo na DPOC: conceitos atuais e perspectivas

A DPOC é uma causa importante de morbidade e mortalidade em escala global. As manifestações clínicas e funcionais da DPOC resultam de danos pulmonares provocados por um conjunto de mecanismos, incluindo o estresse oxidativo, a inflamação, o desequilíbrio do sistema protease-antiprotease e a apoptose. O estresse oxidativo é central na gênese da DPOC, pois além de provocar dano direto às estruturas pulmonares, amplifica os demais mecanismos. Os eventos celulares e moleculares responsáveis pelo dano pulmonar antecedem em muito a expressão clínica e funcional da DPOC. Os broncodilatadores, principais drogas empregadas atualmente no tratamento da DPOC, não são eficazes em reduzir a progressão da doença. Avanços na compreensão da patogênese da DPOC aliados a esforços renovados na pesquisa básica e clínica deverão permitir sua detecção na fase pré-clínica e possibilitar um monitoramento mais adequado de sua atividade, além de permitir a introdução de novas modalidades de agentes terapêuticos capazes de impedir eficazmente sua progressão.

Elevated TNFalpha production in whole blood in patients with severe COPD: the potential link to disease severity

OBJECTIVE

The relationship between tumour necrosis factor-alpha (TNFalpha), severity of pulmonary disease and nutritional depletion in chronic obstructive pulmonary disease (COPD) remains unclear. We aimed to clarify the role of lipopolysaccharide (LPS) as a potential stimulus of cytokine production and the role of these cytokines in the alteration of body composition in patients with different degrees of COPD.

PATIENTS AND METHODS

We studied 29 weight-stable out-patients with different severites of COPD who had no evidence of recent infection or significant co-morbidity. Baseline serum TNFalpha levels and TNFalpha response to LPS in whole blood were measured in patients and 20 aged matched controls.

RESULTS

Serum TNFalpha was significantly elevated in patients versus controls (2.1 +/- 0.3 vs. 1.1 +/- 0.1 pg/ml, mean +/- SEM, P = 0.007). In patients with COPD, we found a significant correlation between serum TNFalpha levels and disease severity, assessed as FEV(1) %predicted (r = 0.49, P = 0.02). Response to lipopolysaccharide did not differ significantly between patients and controls. However, within the patient group those with more severe disease (FEV(1) < or = 30% predicted, n = 12) had an enhanced response compared to patients with mild-to-moderate disease (all P < 0.05 for LPS > 1 ng/ml). Spontaneous TNFalpha production was 5.0 times higher in patients with severe COPD compared to mild-to-moderate COPD (P = 0.02). There was no relation between body composition and serum TNFalpha or TNFalpha response to LPS.

CONCLUSION

Increasing airflow obstruction and hypercapnia are associated with an enhanced TNFalpha response in COPD.

Impact of chronic obstructive pulmonary disease (COPD) on attention functions

The present study investigates the influence of COPD on attention functions, learning, and logical thinking. Therefore, 60 COPD patients and 60 healthy controls were recruited into a cross-sectional study and underwent extensive neuropsychological testing. The Attention Network Test was used for assessment of tonic and phasic alertness, orienting, and executive attention. Logical thinking and learning were determined with the Standard Progressive Matrices and the Verbal and Nonverbal Learning Test, respectively. Significant group differences were found in phasic alertness (p=0.001) and orienting (p=0.01) but not in executive attention. In addition overall reaction time was significantly slower in the COPD group (p=0.001). Further group differences were found in verbal (p<0.001) and visual learning (p<0.001) and logical thinking (p<0.001). Regression analysis revealed significant correlations for age (p=0.024) and blood carbon dioxide levels (p=0.043) in reaction time, a correlation for age and orienting (p=0.019) and finally for age (p=0.011) as well as for blood carbon dioxide values (p=0.048) and performance in logical thinking. Results are indicating a global impairment in cognitive functions of COPD patients which is negatively influenced by accelerated aging and increasing with disease severity.

Skeletal muscle dysfunction in COPD: clinical and laboratory observations

COPD (chronic obstructive pulmonary disease), although primarily a disease of the lungs, exhibits secondary systemic manifestations. The skeletal muscles are of particular interest because their function (or dysfunction) not only influences the symptoms that limit exercise, but may contribute directly to poor exercise performance. Furthermore, skeletal muscle weakness is of great clinical importance in COPD as it is recognized to contribute independently to poor health status, increased healthcare utilization and even mortality. The present review describes the current knowledge of the structural and functional abnormalities of skeletal muscles in COPD and the possible aetiological factors. Increasing knowledge of the molecular pathways of muscle wasting will lead to the development of new therapeutic agents and strategies to combat COPD muscle dysfunction.

Tumor necrosis factor alpha as a marker of systemic and local inflammation in "healthy" smokers

BACKGROUND

Tobacco smoking induces a local and systemic inflammatory reaction and also a decline in pulmonary function. There are some novel noninvasive methods to measure the degree of inflammatory bronchial reaction, including the exhaled breath condensate (EBC) in which several inflammatory markers can be measured, including tumor necrosis factor alpha (TNF-alpha). There is a clear clinical need to develop methods that allow early detection of smokers at risk of losing pulmonary function.

OBJECTIVES

THE AIMS OF THE PRESENT STUDY ARE: 1) to show that smokers show higher levels of TNF-alpha both in serum and EBC; 2) to analyze the possible influence of gender, age, and weight on this parameter; and 3) to determine a possible association between smoking and pulmonary function parameters and TNF-alpha levels.

MATERIAL AND METHODS

We have prospectively analyzed two cohorts of smokers and non-smokers subjects without any chronic or acute disease (within eight weeks of study initiation). We have performed pulmonary function tests with bronchodilators and also collected EBC and blood samples before smoking cessation. Statistical analysis was performed with SPSS 11.0 for Windows Statistical Package.

RESULTS

The study has enrolled 17 patients (8 smokers), 50% of whom were females. Mean age was 38.59 years old (standard deviation, 7.4). The mean number of cigarettes smoked in the smoker group was 26.14 (11.29) cigarettes/day and the mean age when tobacco first began was 15.14 (2.04) years. We have not been able to show any significant differences in TNF-alpha levels according to age or weight. For the whole series we have not found any significant influence of gender in TNF-alpha levels, but after dividing the series in smokers and nonsmokers, we have shown higher levels of TNF-alpha in serum (5.59 [0.26] pg/mL vs 5.56 [0.37] pg/mL; nonsignificant [NS]) and EBC (4.94 [0.41] pg/mL vs 4.22 [0.36] pg/mL; p = 0.031) in male smokers. On the other hand, nonsmoking females showed slightly higher TNF-alpha levels in serum (5.70 [0.50] pg/mL vs 5.42 [0.29] pg/mL; NS) and EBC (4.54 [0.92] vs 4.11 [0.41 pg/mL]; NS). Smokers had higher TNF-alpha levels in EBC (4.46 [0.58] pg/mL vs 4.34 [0.62] pg/mL; NS), while serum TNF-alpha levels were slightly higher in nonsmokers (5.52 [0.56] pg/mL vs 5.50 [0.27] pg/mL; NS). We have not demonstrated any association between tobacco consumption and TNF-alpha levels. We have not shown any significant relation between pulmonary function and the studied parameters, with only a modest association between forced expiratory volume at one second and forced vital capacity and TNF-alpha levels in EBC.

CONCLUSION

Smokers show higher TNF-alpha levels in EBC. Among smokers, males show higher levels of TNF in serum and EBC. We have not confirmed any significant influence of age or weight on TNF-alpha levels. These levels do not seem to be influenced either by the amount of tobacco or the time since habit began. We have shown a modest relation between pulmonary function and TNF-alpha levels in EBC.

Chronic obstructive pulmonary disease and obstructive sleep apnea: overlaps in pathophysiology, systemic inflammation, and cardiovascular disease

Chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea syndrome represent two of the most prevalent chronic respiratory disorders in clinical practice, and cardiovascular diseases represent a major comorbidity in each disorder. The two disorders coexist (overlap syndrome) in approximately 1% of adults but asymptomatic lower airway obstruction together with sleep-disordered breathing is more prevalent. Although obstructive sleep apnea syndrome has similar prevalence in COPD as the general population, and vice versa, factors such as body mass index and smoking influence relationships. Nocturnal oxygen desaturation develops in COPD, independent of apnea/hypopnea, and is more severe in the overlap syndrome, thus predisposing to pulmonary hypertension. Furthermore, upper airway flow limitation contributes to nocturnal desaturation in COPD without apnea/hypopnea. Evidence of systemic inflammation in COPD and sleep apnea, involving C-reactive protein and IL-6, in addition to nuclear factor-kappaB-dependent pathways involving tumor necrosis factor-alpha and IL-8, provides insight into potential basic interactions between both disorders. Furthermore, oxidative stress develops in each disorder, in addition to activation and/or dysfunction of circulating leukocytes. These findings are clinically relevant because systemic inflammation may contribute to the pathogenesis of cardiovascular diseases and the cell/molecular pathways involved are similar to those identified in COPD and sleep apnea. However, the pathophysiological and clinical significance of systemic inflammation in COPD and sleep apnea is not proven, and thus, studies of patients with the overlap syndrome should provide insight into the mechanisms of systemic inflammation in COPD and sleep apnea, in addition to potential relationships with cardiovascular disease.

Cigarette smoke impairs clearance of apoptotic cells through oxidant-dependent activation of RhoA

RATIONALE

Cigarette smoke (CS) is the primary cause of chronic obstructive pulmonary disease (COPD), an effect that is, in part, due to intense oxidant stress. Clearance of apoptotic cells (efferocytosis) is a critical regulator of lung homeostasis, which is defective in smokers and in patients with COPD, suggesting a role in disease pathogenesis.

OBJECTIVES

We hypothesized that CS would impair efferocytosis through oxidant-dependent activation of RhoA, a known inhibitor of this process.

METHODS

We investigated the effect of CS on efferocytosis in vivo and ex vivo, using acute, subacute, and long-term mouse exposure models.

MEASUREMENTS AND MAIN RESULTS

Acute and subacute CS exposure suppressed efferocytosis by alveolar macrophages in a dose-dependent, reversible, and cell type-independent manner, whereas more intense CS exposure had an irreversible effect. In contrast, CS did not alter ingestion through the Fc gamma receptor. The inhibitory effect of CS on apoptotic cell clearance depended on oxidants, because the effect was blunted in oxidant-resistant ICR mice, and was prevented by either genetic or pharmacologic antioxidant strategies in vivo and ex vivo. CS inhibited efferocytosis through oxidant-dependent activation of the RhoA-Rho kinase pathway because (1) CS activated RhoA, (2) antioxidants prevented RhoA activation by CS, and (3) inhibitors of the RhoA-Rho kinase pathway reversed the suppressive effect of CS on apoptotic cell clearance in vivo and ex vivo.

CONCLUSIONS

These findings advance the hypothesis that impaired efferocytosis may contribute to the pathogenesis of COPD and suggest the therapeutic potential of drugs targeting the RhoA-Rho kinase pathway.

The repeatability of interleukin-6, tumor necrosis factor-alpha, and C-reactive protein in COPD patients over one year

BACKGROUND

Many of the systemic manifestations of chronic obstructive pulmonary disease (COPD) are mediated through increased systemic levels of inflammatory proteins. We assessed the long term repeatability of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), and C-reactive protein (CRP) over one year and examined the relationships between these systemic markers in COPD.

METHODS

Fifty-eight stable COPD patients completed a baseline and one-year visit. Serum IL-6, plasma CRP, and plasma TNF-alpha were measured. Repeatability was expressed by intraclass correlation coefficient (R(i)) and the Bland-Altman method. Pearson correlations were used to determine the relationships between the systemic markers at both visits.

RESULTS

There was moderate repeatability with a very high degree of statistical significance (p <or= 0.001) between the two visits for all the systemic biomarkers (IL-6, CRP, and TNF-alpha). CRP was significantly associated with IL-6 at both visits (r = 0.55, p = 0.0001, r = 0.51, p = 0.0002, respectively). There were no other significant associations between the systemic markers at either of the visits.

CONCLUSIONS

Systemic inflammatory biomarkers IL-6, CRP, and TNF-alpha were moderately repeatable over a twelve month period in COPD patients. We have also shown that a robust and repeatable association between IL-6 and CRP exists.

Skeletal muscle dysfunction in patients with chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a debilitating disease characterized by inflammation-induced airflow limitation and parenchymal destruction. In addition to pulmonary manifestations, patients with COPD develop systemic problems, including skeletal muscle and other organ-specific dysfunctions, nutritional abnormalities, weight loss, and adverse psychological responses. Patients with COPD often complain of dyspnea on exertion, reduced exercise capacity, and develop a progressive decline in lung function with increasing age. These symptoms have been attributed to increases in the work of breathing and in impairments in gas exchange that result from airflow limitation and dynamic hyperinflation. However, there is mounting evidence to suggest that skeletal muscle dysfunction, independent of lung function, contributes significantly to reduced exercise capacity and poor quality of life in these patients. Limb and ventilatory skeletal muscle dysfunction in COPD patients has been attributed to a myriad of factors, including the presence of low grade systemic inflammatory processes, nutritional depletion, corticosteroid medications, chronic inactivity, age, hypoxemia, smoking, oxidative and nitrosative stresses, protein degradation and changes in vascular density. This review briefly summarizes the contribution of these factors to overall skeletal muscle dysfunction in patients with COPD, with particular attention paid to the latest advances in the field.

Association of chronic obstructive pulmonary disease and obstructive sleep apnea consequences

Obstructive sleep apnea syndrome (OSAS) and chronic obstructive pulmonary disease (COPD) are two diseases that often coexist within an individual. This coexistence is known as overlap syndrome and is the result of chance rather than a pathophysiological link. Although there are claims of a very high incidence of OSAS in COPD patients, recent studies report that it is similar to the general population. Overlap patients present sleep-disordered breathing associated to upper and lower airway obstruction and a reduction in respiratory drive. These patients present unique characteristics, which set them apart from either COPD or OSAS patients. COPD and OSAS are independent risk factors for cardiovascular events and their coexistence in overlap syndrome probably increases this risk. The mechanisms underlying cardiovascular risk are still unclear, but may involve systemic inflammation, endothelial dysfunction, and tonic elevation of sympathetic neural activity. The treatment of choice for overlap syndrome in stable patients is CPAP with supplemental oxygen for correction of upper airway obstructive episodes and hypoxemia during sleep.

Exhaled nitric oxide, systemic inflammation, and the spirometric response to inhaled fluticasone propionate in severe chronic obstructive pulmonary disease: a prospective study

BACKGROUND

A subset of patients with chronic obstructive pulmonary disease (COPD) may respond more favorably to inhaled corticosteroids (ICS), but no simple method is currently utilized to predict the presence or absence of ICS responses in patients with COPD.We evaluated the ability of exhaled nitric oxide (FENO) and serum inflammatory markers (C-reactive protein [CRP], interleukin-6 [IL-6], and interleukin-8 [IL-8]) to independently predict spirometric responses to ICS in patients with COPD.

METHODS

Among 60 ex-smokers with severe COPD (mean FEV1 1.07 L, 36% of predicted), we conducted a single-arm, open-label study. Participants spent four weeks free of any ICS, followed by four weeks of ICS use (fluticasone propionate 500 mcg twice daily). FENO, CRP, IL-6, IL-8, and pre-bronchodilator spirometry were measured immediately before and after the four weeks of ICS use.

RESULTS

Baseline FENO, CRP, IL-6, and IL-8 showed no correlations to FEV1 responses to ICS. ICS responders (increase in FEV1 > or = 200 mL after four weeks of ICS) did have significantly higher baseline FENO levels compared with non-responders (46.5 parts per billion [ppb] vs. 25 ppb, p = 0.028). The receiver operating characteristic curve for FENO to discriminate responders from non-responders had an area under curve of 0.72. Baseline serum inflammatory markers did not differ between responders and non-responders.

CONCLUSION

In ex-smokers with severe COPD, a measure of local pulmonary inflammation, FENO, may be more closely associated with FEV1 responses to four weeks of ICS than are standard markers of systemic inflammation, serum CRP, IL-6, and IL-8.

Biomarkers of systemic inflammation in stable and exacerbation phases of COPD

Apart from the deleterious effects on the lungs, chronic obstructive pulmonary disease (COPD) should be considered a complex, systemic disease involving several organs and systems. The nature and course of systemic inflammation in COPD is important since there is a potential for anti-inflammatory therapy. The objective of the current study was to assess biomarkers of systemic inflammation in stable and exacerbation phases of COPD patients as compared to healthy controls. We also investigated the course of these biomarkers after COPD exacerbation to evaluate their usefulness for disease monitoring. Eighty-three stable patients with moderate to very severe COPD, 20 patients in exacerbation phase, and 30 subjects with normal pulmonary function were included. Serum tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), and nitric oxide (NO) levels were measured once in stable COPD patients and controls and three times in the COPD exacerbation group during follow-up. TNF-alpha and IL-6 levels were higher than in controls in both stable and exacerbation groups. Although NO was not higher in the stable COPD group than in controls, it was higher in the exacerbation group. In follow-up after the exacerbation period, significant alteration was not detected in cytokine or NO levels compared to admission. Raised serum levels of TNF-alpha and IL-6 support their use as biomarkers of the systemic inflammatory response in stable COPD patients. However, the circulating biomarkers we have studied are not found to be useful either as indicators of COPD exacerbation or for monitoring recovery after exacerbation.

Anti-TNF-alpha therapies in chronic obstructive pulmonary diseases

BACKGROUND

Chronic obstructive pulmonary disease (COPD) and asthma are chronic diseases in which inflammation of the airways leads to progressive transient airway obstruction and TNF-alpha plays an important pro-inflammatory role.

OBJECTIVE

To assess the plausibility of anti-TNF-alpha therapies playing an anti-inflammatory role in asthma and COPD.

METHODS

Scientific rationale of TNF-alpha targeting in asthma and COPD was assessed individually and the available data on the use of anti-TNF-alpha in each disease were reviewed.

RESULTS AND CONCLUSION

Anti-TNF-alpha therapies demonstrate different efficacies in asthma and COPD and further supportive preclinical and clinical data are needed, especially about subsets of certain diseases which could benefit the most from these therapies.

Inhaled and systemic corticosteroids in chronic obstructive pulmonary disease

Systemic and local inflammation is central to the pathophysiology of chronic obstructive pulmonary disease (COPD). Increased levels of inflammation have been linked to a more progressive course in COPD and have been shown to be present during an exacerbation. Decreases in inflammatory cytokines, C-reactive protein, and inflammatory cells have been observed with corticosteroid use, suggesting a possible mechanism for a therapeutic benefit of steroids. No available data support the routine use of systemic corticosteroids in stable COPD; however, short courses during exacerbations are likely to improve length of hospitalization, lung function, and relapse rate. Inhaled corticosteroids (ICS) decrease the rate of exacerbation and may improve the response to bronchodilators and decrease dyspnea in stable COPD. No study shows that ICS reduce the loss of lung function; however, recent data suggest a possible survival benefit when combined with long-acting beta agonists. There are limited data on the use of ICS in the treatment of acute exacerbations of COPD, and its role in this setting must be more clearly defined. The empiric use of systemic corticosteroids perioperatively represents another area of uncertainty. The role of pharmacogenetics in the metabolism of corticosteroids in COPD is evolving but may be partially responsible for the observed variability in patient responsiveness. The potential benefits of systemic or inhaled corticosteroid use must be weighed against the risk of known toxicities.

Altered expression of antimicrobial molecules in cigarette smoke-exposed emphysematous mice lungs

BACKGROUND AND OBJECTIVE

The natural history of COPD, a disease usually caused by cigarette smoking, is associated with frequent respiratory infections. Consistent with human COPD, bacterial clearance in the lungs has been reported to be impaired in mice exposed to cigarette smoke. In the airways, several antimicrobial molecules such as surfactant proteins (SP), beta-defensins (BD), secretory leucocyte protease inhibitor (SLPI) and lysozyme play important roles in the defence against invading pathogens. This study evaluated the expression of antimicrobial molecules in mice lungs with cigarette smoke-induced emphysematous changes.

METHODS

Six B6C3F1 mice were exposed to cigarette smoke (2 cigarettes/day/mouse for 6 months) or room air. Gene expression within the lungs of mice in both groups was assessed by RT-PCR.

RESULTS

The expression of SP-A, BD2, BD3 and SLPI was significantly elevated in the lungs of cigarette smoke-exposed mice compared with air-exposed mice. BD1 expression decreased in the smoke-exposed mice and lysozyme expression was unchanged.

CONCLUSIONS

Chronic cigarette smoke exposure did not suppress the expression of antimicrobial molecules in the lung. Altered expression of antimicrobial molecules in this mouse model does not explain the impaired host defence against respiratory microbes seen in patients with COPD.

Energy expenditure and respiratory diseases: is there a link?

Recent studies have suggested that respiratory diseases, such as chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea syndrome (OSAS), influence energy expenditure (EE). This influence on energy balance may be responsible for the weight changes that are often seen in individuals suffering from OSAS and COPD. However, even though EE has been assessed in several studies, be it in OSAS or COPD, there are still controversies regarding these potential relationships. Thus, the objective of this review is to describe some of the potential mechanisms that may affect EE in respiratory diseases and, thereby discuss whether there seems to be an explanation for the aforementioned relationship. The primary focus is on the oxygen transport system, which may be an important determinant for the relationship between both of these respiratory diseases and EE.

COPD as a systemic disease

Chronic obstructive pulmonary disease (COPD) represents an important and increasing burden throughout the world. Classically, COPD has been considered a respiratory condition only, mainly caused by tobacco smoking. However, COPD has important manifestations beyond the lungs, the so-called systemic effects. These include unintentional weight loss, skeletal muscle dysfunction, an increased risk of cardiovascular disease, osteoporosis, and depression, among others. Low-grade, chronic systemic inflammation is one of the key mechanisms underlying these systemic effects. Because these extra-pulmonary manifestations of COPD are common and/or may have significant implications for the patient wellbeing and prognosis, they warrant systematic screening and appropriate management in order to provide optimal medical care.

Mechanisms of atherothrombosis in chronic obstructive pulmonary disease

Patients affected by chronic obstructive pulmonary disease (COPD) have an increased risk of atherothrombotic acute events, independent of smoking and other cardiovascular risk factors. As a consequence, myocardial ischemia is a relevant cause of death in these patients. We reviewed studies concerning the potential mechanisms of atherothrombosis in COPD. Bronchial inflammation spreads to the systemic circulation and is known to play a key role in plaque formation and rupture. In fact, C-reactive protein blood levels increase in COPD and provide independent prognostic information. Systemic inflammation is the first cause of the hypercoagulable state commonly observed in COPD. Furthermore, hypoxia is supposed to activate platelets, thus accounting for the increased urinary excretion of platelet-derived thromboxane in COPD. The potential metabolic risk in COPD is still debated, in that recent studies do not support an association between COPD and diabetes mellitus. Finally, oxidative stress contributes to the pathogenesis of COPD and may promote oxidation of low-density-lipoproteins with foam cells formation. Retrospective observations suggest that inhaled corticosteroids may reduce atherothrombotic mortality by attenuating systemic inflammation, but this benefit needs confirmation in ongoing randomized controlled trials. Physicians approaching COPD patients should always be aware of the systemic vascular implications of this disease.

Impact of nutritional status on body functioning in chronic obstructive pulmonary disease and how to intervene

PURPOSE OF REVIEW

Chronic obstructive pulmonary disease is the fifth leading cause of mortality in the world. This study reviews diet as a risk or protective factor for chronic obstructive pulmonary disease, mechanisms of malnutrition, undernutrition consequences on body functioning and how to modulate nutritional status of patients with chronic obstructive pulmonary disease.

RECENT FINDINGS

Different dietary factors (dietary pattern, foods, nutrients) have been associated with chronic obstructive pulmonary disease and the course of the disease. Mechanical disadvantage, energy imbalance, disuse muscle atrophy, hypoxemia, systemic inflammation and oxidative stress have been reported to cause systemic consequences such as cachexia and compromise whole body functioning. Nutritional intervention makes it possible to modify the natural course of the disease provided that it is included in respiratory rehabilitation combining bronchodilators optimization, infection control, exercise and, in some patients, correction of hypogonadism.

SUMMARY

Diet, as a modifiable risk factor, appears more as an option to prevent and modify the course of chronic obstructive pulmonary disease. Reduction of mechanical disadvantage, physical training and anabolic agents should be used conjointly with oral nutrition supplements to overcome undernutrition and might change the prognosis of the disease in some cases. Major research challenges address the role of systemic inflammation and the best interventions for controlling it besides smoking cessation.

TNF alpha receptor genotype influences smoking-induced muscle-fibre-type shift and atrophy in mice

Systemic manifestations of chronic obstructive pulmonary disease (COPD) include muscle wasting, and tumour necrosis factor alpha (TNFalpha) could represent a major inducer of these processes. We studied skeletal muscle histology in a murine model of cigarette smoke (CS)-induced COPD, comparing mice with different TNFalpha receptor genotypes. Muscles from hind limbs of wild type (WT), TNFalpha receptor 1 knockout (TNF alpha R1KO) and TNF alpha R2KO mice were prepared and weighed. The lower body weight, which was observed in CS-exposed WT and TNF alpha R1KO mice, was paralleled by reduced weights of gastrocnemius and biceps femoris muscle. The gastrocnemius muscle was evaluated for muscle fibre apoptosis and atrophy, and fibre-type distribution. CS-induced apoptosis was observed in all genotypes, while a significant reduction of cross-sectional areas of myofibres was present only in TNF alpha R2KO mice. A CS-induced fibre-type shift from the IIa to the IIb phenotype was observed in WT mice, an increase of muscle-fibre-type IIx was noticed in CS-exposed TNF alpha R2KO mice. Our data suggest that the skeletal muscle manifestations associated with this murine COPD model are under complex regulation by both TNFalpha receptors, but that TNF alpha R2 may be the most important determinant for the outcome of CS-induced myofibre apoptosis.

[The association between bronchiectasis, systemic inflammation, and tumor necrosis factor alpha]

OBJECTIVE

The relationship between systemic inflammation and different measures of bronchiectasis severity has not been described. The objective of this study was to analyze the relationship between plasma concentrations of tumor necrosis factor alpha (TNF-alpha), as a marker of systemic inflammation, and some commonly used criteria for quantifying bronchiectasis severity in clinically stable patients whose disease was not caused by cystic fibrosis.

PATIENTS AND METHODS

Sixty-eight clinically stable patients with bronchiectasis and 19 age- and sex-matched healthy control subjects were included in the study. Data on disease history, symptoms, severity, functional variables, sputum volume, and microbiological cultures, laboratory findings, and other indicators of disease course were collected. Plasma concentrations of TNF-alpha were measured using high-resolution enzyme-linked immunoabsorbent assay.

RESULTS

Plasma concentrations of TNF-alpha were higher in patients than controls (8.28 vs 5.67 pg/mL; P=.001). This observation correlated with other markers of systemic inflammation such as erythrocyte sedimentation rate (r=0.42; P=.001), C-reactive protein (rho=0.45; P=.001), and percentage of peripheral blood neutrophils (rho=0.45; P=.001). Patients with high plasma concentrations of TNF-alpha (>8.1 pg/dL) had more severe disease (5.19 vs 3.21; P=.001), were more likely to have respiratory failure (37.5% vs 8.3%; P=.003), and a higher rate of Pseudomonas aeruginosa colonization (34.3% vs 8.3%; P=.008).

CONCLUSIONS

High plasma concentrations of TNF-alpha were associated with several criteria usually used to assess severity of bronchiectasis in clinically stable patients with disease not caused by cystic fibrosis.

Hypoxia enhances lysosomal TNF-alpha degradation in mouse peritoneal macrophages

Infection, simulated by lipopolysaccharide (LPS), is a potent stimulator of tumor necrosis factor-alpha (TNF-alpha) production, and hypoxia often synergizes with LPS to induce higher levels of the secreted cytokine. However, we show that in primary mouse peritoneal macrophages and in three mouse peritoneal macrophage cell lines (RAW 264.7, J774A.1, and PMJ-2R), hypoxia (O(2) < 0.3%) reduces the secretion of LPS-induced TNF-alpha (P < 0.01). In RAW 264.7 cells this reduction was not regulated transcriptionally as TNF-alpha mRNA levels remained unchanged. Rather, hypoxia and LPS reduced the intracellular levels of TNF-alpha by twofold (P < 0.01) by enhancing its degradation in the lysosomes and inhibiting its secretion via secretory lysosomes, as shown by confocal microscopy and verified by the use of the lysosome inhibitor Bafilomycin A1. In addition, although hypoxia did not change the accumulation of the soluble receptor TNF-RII, it increased its binding to the secreted TNF-alpha by twofold (P < 0.05). We suggest that these two posttranslational regulatory checkpoints coexist in hypoxia and may partially explain the reduced secretion and diminished biological activity of TNF-alpha in hypoxic peritoneal macrophages.