Cigarette smoking is a major risk factor in the development of age-related chronic obstructive pulmonary disease (COPD). The serotonin transporter (SERT) gene polymorphism has been reported to be associated with COPD, and the degree of cigarette smoking has been shown to be a significant mediator in this relationship. The interrelation between circulating serotonin (5-hydroxytyptamine, 5-HT), cigarette smoking and COPD is however largely unknown. The current study aimed at investigating the mediation effects of plasma 5-HT on cigarette smoking-induced COPD and the relation between plasma 5-HT levels and age.
The association between plasma 5-HT, age and COPD was analyzed in a total of 62 COPD patients (ever-smokers) and 117 control subjects (healthy non-smokers and ever-smokers). Plasma 5-HT levels were measured by enzyme-linked immuno assay (EIA).
The elevated plasma 5-HT levels were significantly associated with increased odds for COPD (OR = 1.221, 95% CI = 1.123 to 1.319, p<0.0001). The effect remained significant after being adjusted for age and pack-years smoked (OR = 1.271, 95% CI = 1.134 to 1.408, p = 0.0003). Furthermore, plasma 5-HT was found to mediate the relation between pack-years smoked and COPD. A positive correlation (r = 0.303, p = 0.017) was found between plasma 5-HT levels and age in COPD, but not in the control subjects (r = −0.149, p = 0.108).
Our results suggest that cigarette smoke-induced COPD is partially mediated by the plasma levels of 5-HT, and that these become elevated with increased age in COPD. The elevated plasma 5-HT levels in COPD might contribute to the pathogenesis of this disease.
Rationale: Oxidative stress is a key contributor in chronic obstructive pulmonary disease (COPD) pathogenesis caused by cigarette smoking. NRF2, a redox-sensitive transcription factor, dissociates from its inhibitor, KEAP1, to induce antioxidant expression that inhibits oxidative stress.
Objectives: To determine the link between severity of COPD, oxidative stress, and NRF2-dependent antioxidant levels in the peripheral lung tissue of patients with COPD.
Methods: We assessed the expression of NRF2, NRF2-dependent antioxidants, regulators of NRF2 activity, and oxidative damage in non-COPD (smokers and former smokers) and smoker COPD lungs (mild and advanced). Cigarette smoke–exposed human lung epithelial cells (Beas2B) and mice were used to understand the mechanisms.
Measurements and Main Results: When compared with non-COPD lungs, the COPD patient lungs showed (1) marked decline in NRF2-dependent antioxidants and glutathione levels, (2) increased oxidative stress markers, (3) significant decrease in NRF2 protein with no change in NRF2 mRNA levels, and (4) similar KEAP1 but significantly decreased DJ-1 levels (a protein that stabilizes NRF2 protein by impairing KEAP1-dependent proteasomal degradation of NRF2). Exposure of Bea2B cells to cigarette smoke caused oxidative modification and enhanced proteasomal degradation of DJ-1 protein. Disruption of DJ-1 in mouse lungs, mouse embryonic fibroblasts, and Beas2B cells lowered NRF2 protein stability and impaired antioxidant induction in response to cigarette smoke. Interestingly, targeting KEAP1 by siRNA or the small-molecule activator sulforaphane restored induction of NRF2-dependent antioxidants in DJ-1–disrupted cells in response to cigarette smoke.
Conclusions: NRF2-dependent antioxidants and DJ-1 expression was negatively associated with severity of COPD. Therapy directed toward enhancing NRF2-regulated antioxidants may be a novel strategy for attenuating the effects of oxidative stress in the pathogenesis of COPD.
chronic obstructive pulmonary disease; NRF2; DJ-1; oxidative stress; antioxidants
Previous studies have shown links between anxiety and depression and chronic obstructive pulmonary disease (COPD), but little is known about possible mechanisms of this association. The current study examined whether the observed relationship between anxiety and depression and COPD is explained by confounding due to cigarette smoking and lifetime nicotine dependence.
Data were drawn from the National Comorbidity Survey Replication, a community-based representative sample of adults in the United States.
Analyses suggest that the association between anxiety disorders and COPD appears to be largely explained by confounding by former cigarette smoking and lifetime nicotine dependence. The association between mood disorders and COPD appears to be largely explained by confounding by lifetime nicotine dependence.
These findings provide initial evidence suggesting that the association between anxiety, depression, and COPD may be at least partly attributable to confounding by cigarette smoking and nicotine dependence. Efforts toward prevention of chronic lung disease may be more effective if treatment and prevention efforts aimed at smoking cessation address mental health problems.
Previous studies have suggested links between chronic obstructive pulmonary disease (COPD), cardiovascular disease, and abdominal obesity. Although abdominal visceral fat is thought to be associated with cardiovascular risk factors, the degree of visceral fat accumulation in patients with COPD has not been directly studied. The aim of this study was to investigate the abdominal visceral fat accumulation and the association between visceral fat and the severity and changes in emphysema in COPD patients.
We performed clinical and laboratory tests, including pulmonary function, dyspnea score, and the six-minute walking test in COPD patients (n = 101) and control, which included subjects with a smoking history but without airflow obstruction (n = 62). We used computed tomography to evaluate the abdominal visceral fat area (VFA), subcutaneous fat area (SFA), and the extent of emphysema.
The COPD group had a larger VFA than the control group. The prevalence of non-obese subjects with an increased VFA was greater in the Global Initiative for Chronic Obstructive Lung Disease Stages III and IV than in the other stages of COPD. The extent of emphysema was inversely correlated with waist circumference and SFA. However, VFA did not decrease with the severity of emphysema. VFA was positively correlated with the degree of dyspnea.
COPD patients have excessive visceral fat, which is retained in patients with more advanced stages of COPD or severe emphysema despite the absence of obesity.
abdominal obesity; chronic obstructive pulmonary disease; emphysema; visceral fat
Although smoking is the major causal factor in the development of chronic obstructive pulmonary disease (COPD), only 10–20% of chronic heavy cigarette smokers develop symptomatic COPD, which suggests the presence of genetic susceptibility. The human microsomal epoxide hydrolase (EH) is a metabolizing enzyme which involves the process of numerous reactive epoxide intermediates and contains polymorphic alleles which are associated with altered EH activity and may be linked to increased risk for COPD. To determine whether the EH polymorphisms contributed to increased risk for COPD, prevalence of the EH codons 113 and 139 polymorphisms were compared between COPD patients and controls using a PCR-RFLP analysis using genomic DNA isolated from 131 COPD patients and 262 individually matched controls by age (± 5 years) among Caucasians with 1:2 ratio. Significantly increased risk for COPD was observed for subjects with the EH113His/His genotypes (OR =2.4, 95% CI=1.1–5.1). These results were consistent with the fact that a significant trend towards increased risk was observed with predicted less protective EH codon 113 genotypes (p = 0.03, trend test). A similar association was not observed for EH codon139 polymorphism. As expected, a significant correlation between smoking dose and severity of COPD was observed (p<0.001). These results suggest that EH codon 113 polymorphism may modify risk for COPD.
chronic obstructive pulmonary disease; epoxide hydrolase; genetic polymorphism; genetic susceptibility
Rationale: Adaptive immune responses are present in patients with chronic obstructive pulmonary disease (COPD), and it has been postulated that these processes could be autoreactive.
Objectives: To ascertain if humoral autoimmunity could play a role in COPD pathogenesis.
Methods: Circulating IgG autoantibodies were detected by immunofluorescence and immunoprecipitation. Immunohistochemistry and immunofluorescence were used to evaluate intrapulmonary IgG and complement (C3) deposition in human lung explants. Autoantibody pathogenicity was also investigated with an antibody-dependent cell-mediated cytotoxicity assay.
Measurements and Main Results: The prevalence of anti–HEp-2 epithelial cell autoantibodies in 47 smokers/former smokers with COPD (GOLD stages 1–4) was greater than among 8 subjects with a smoking history but normal spirometry and 21 healthy control subjects who had never smoked (68 vs. 13 vs. 10%, respectively; P < 0.0001). Antibodies against primary pulmonary epithelial cells were found in 12 of 12 patients with COPD versus 3 of 12 never-smoked control subjects (P < 0.001). Self-antigens immunoprecipitated from 34 of 35 (97%) of COPD plasmas (vs. 0/12 never-smoked controls). Antibodies against a particular 130-kD autoantigen (n = 7) were associated with decreased body mass index (23.2 ± 2.1 vs. 29.5 ± 1.0 kg/m2, P = 0.007). Intrapulmonary immune complexes were present in six of six and C3 was seen in five of six COPD lung explants, unlike zero of six and one of six normals, respectively. Cytotoxicity of pulmonary epithelial cells by allogeneic mononuclear cells also increased 46% after incubation with COPD plasmas (n = 10), compared with identical treatments with eight normal specimens (P = 0.03).
Conclusions: IgG autoantibodies with avidity for pulmonary epithelium, and the potential to mediate cytotoxicity, are prevalent in patients with COPD. Autoreactive adaptive immune responses may be important in the etiology of this disease.
autoimmunity; humoral immunity; B cells; emphysema
An association between HIV infection and chronic obstructive pulmonary disease (COPD) has been observed in several studies.
Objective and methods
we conducted a review of the literature linking HIV infection to COPD, focusing on clinical and epidemiological data published before and during widespread highly active antiretroviral therapy (HAART).
Interactions between HIV infection and COPD appear to be influenced by multiple factors. In particular, the bronchopulmonary tract can be damaged by HIV infection, the immunodeficiency it induces, and the resulting increase in the risk of pulmonary infections. In addition, the prevalence of smoking and intravenous drug use is higher in HIV-infected populations, also increasing the risk of COPD. Before the advent of HAART, respiratory tract infections probably played a major role. Since the late 1990s and the widespread use of HAART, the frequency of opportunistic infections has fallen but new complications have emerged as life expectancy has increased.
given the high prevalence of smoking among HIV-infected patients, COPD may contribute significantly to morbidity and mortality in this setting.
Lung cancer is the leading cause of cancer deaths in the United States. In addition to genetic abnormalities induced by cigarette smoke, several epidemiologic studies have found that smokers with chronic obstructive pulmonary disease (COPD), an inflammatory disease of the lungs, have an increased risk of lung cancer (1.3- to 4.9-fold) compared to smokers without COPD. This suggests a link between chronic airway inflammation and lung carcinogenesis, independent of tobacco smoke exposure. We studied this association by assaying the inflammatory impact of products of nontypeable Haemophilus influenzae, which colonizes the airways of patients with COPD, on lung cancer promotion in mice with an activated K-ras mutation in their airway epithelium. Two new mouse models of lung cancer were generated by crossing mice harboring the LSL–K-rasG12D allele with mice containing Cre recombinase inserted into the Clara cell secretory protein (CCSP) locus, with or without the neomycin cassette excised (CCSPCre and CCSPCre-Neo, respectively). Lung lesions in CCSPCre-Neo/LSL–K-rasG12D and CCSPCre/LSL–K-rasG12D mice appeared at 4 and 1 month of age, respectively, and were classified as epithelial hyperplasia of the bronchioles, adenoma, and adenocarcinoma. Weekly exposure of CCSPCre/LSL–K-rasG12D mice to aerosolized nontypeable Haemophilus influenzae lysate from age 6–14 weeks resulted in neutrophil/macrophage/CD8 T-cell–associated COPD-like airway inflammation, a 3.2-fold increase in lung surface tumor number (156 ± 9 versus 45 ± 7), and an increase in total lung tumor burden. We conclude that COPD-like airway inflammation promotes lung carcinogenesis in a background of a G12D-activated K-ras allele in airway secretory cells.
K-ras; lung cancer; inflammation
Recent studies have demonstrated that K-ras mutations in lung epithelial cells elicit inflammation that promotes carcinogenesis in mice (intrinsic inflammation). The finding that patients with chronic obstructive pulmonary disease (COPD), an inflammatory disease of the lung, have an increased risk of lung cancer after controlling for smoking suggests a further link between lung cancer and extrinsic inflammation. Besides exposure to cigarette smoke, it is thought that airway inflammation in COPD is caused by bacterial colonization, particularly with non-typeable Hemophilus influenzae (NTHi). Previously, we have shown that NTHi-induced COPD-like airway inflammation promotes lung cancer in an airway conditional K-ras-induced mouse model. To further test the role of inflammation in cancer promotion, we administered the natural anti-inflammatory agent, curcumin, 1% in diet before and during weekly NTHi exposure. This significantly reduced the number of visible lung tumors in the absence of NTHi exposure by 85% and in the presence of NTHi exposures by 53%. Mechanistically, curcumin markedly suppressed NTHi-induced increased levels of the neutrophil chemoattractant keratinocyte-derived chemokine by 80% and neutrophils by 87% in bronchoalveolar lavage fluid. In vitro studies of murine K-ras-induced lung adenocarcinoma cell lines (LKR-10 and LKR-13) indicated direct anti-tumoral effects of curcumin by reducing cell viability, colony formation and inducing apoptosis. We conclude that curcumin suppresses the progression of K-ras-induced lung cancer in mice by inhibiting intrinsic and extrinsic inflammation and by direct anti-tumoral effects. These findings suggest that curcumin could be used to protract the premalignant phase and inhibit lung cancer progression in high-risk COPD patients.
The identification and validation of biomarkers to support the assessment of novel therapeutics for COPD continues to be an important area of research. The aim of the current study was to identify systemic protein biomarkers correlated with measures of COPD severity, as well as specific protein signatures associated with comorbidities such as metabolic syndrome. 142 protein analytes were measured in serum of 140 patients with stable COPD, 15 smokers without COPD and 30 non-smoking controls. Seven analytes (sRAGE, EN-RAGE, NGAL, Fibrinogen, MPO, TGF-α and HB-EGF) showed significant differences between severe/very severe COPD, mild/moderate COPD, smoking and non-smoking control groups. Within the COPD subjects, univariate and multivariate analyses identified analytes significantly associated with FEV1, FEV1/FVC and DLCO. Most notably, a set of 5 analytes (HB-EGF, Fibrinogen, MCP-4, sRAGE and Sortilin) predicted 21% of the variability in DLCO values. To determine common functions/pathways, analytes were clustered in a correlation network by similarity of expression profile. While analytes related to neutrophil function (EN-RAGE, NGAL, MPO) grouped together to form a cluster associated with FEV1 related parameters, analytes related to the EGFR pathway (HB-EGF, TGF-α) formed another cluster associated with both DLCO and FEV1 related parameters. Associations of Fibrinogen with DLCO and MPO with FEV1/FVC were stronger in patients without metabolic syndrome (r = −0.52, p = 0.005 and r = −0.61, p = 0.023, respectively) compared to patients with coexisting metabolic syndrome (r = −0.25, p = 0.47 and r = −0.15, p = 0.96, respectively), and may be driving overall associations in the general cohort. In summary, our study has identified known and novel serum protein biomarkers and has demonstrated specific associations with COPD disease severity, FEV1, FEV1/FVC and DLCO. These data highlight systemic inflammatory pathways, neutrophil activation and epithelial tissue injury/repair processes as key pathways associated with COPD.
Cigarette smoke is the major risk factor associated with the development of chronic obstructive pulmonary disease (COPD). Recent studies propose a link between endoplasmic reticulum (ER) stress and emphysema, demonstrated by increased ER stress markers under smoking conditions. Here, we investigate whether cigarette smoke-induced ER stress is cell specific and correlates with acute and chronic cigarette smoke exposure.
Gene and protein expression changes in human primary lung cell cultures following cigarette smoke extract (CSE) exposure were monitored by qPCR and Western blot analysis. Mice and guinea pigs were exposed to cigarette smoke and ER stress markers examined in whole lung homogenates. Inflammatory cells from the bronchoalveolar lavage fluid of 10 days smoke exposed mice were also examined.
Cigarette smoke induced a trend increase in the ER stress response through an activating transcription factor 4 (ATF4) mediated induction of C/EBP homologous protein (CHOP) in primary small airway epithelial cells. Bronchial epithelial cells and macrophages responded similarly to CSE. Wild-type mice and guinea pigs exposed to acute levels of cigarette smoke exhibited increased levels of CHOP but not at significant levels. However, after long-term chronic cigarette smoke exposure, CHOP expression was reduced. Interestingly, inflammatory cells from smoke exposed mice had a significant increase in CHOP/ATF4 expression.
A trend increase in CHOP levels appear in multiple human lung cell types following acute cigarette smoke exposure in vitro. In vivo, inflammatory cells, predominately macrophages, demonstrate significant cigarette smoke-induced ER stress. Early induction of CHOP in cigarette smoke may play a pivotal role in early induction of lung disease, however in vivo long-term cigarette smoke exposure exhibited a reduction in the ER stress response.
COPD; ER stress; cigarette smoke; CHOP
We examined the association between single-nucleotide polymorphisms (SNPs) previously associated with chronic obstructive pulmonary disease (COPD) and/or lung function with COPD and COPD-related phenotypes in a novel cohort of patients with severe to very severe COPD. We examined 315 cases of COPD and 330 Caucasian control smokers from Poland. We included three SNPs previously associated with COPD: rs7671167 (FAM13A), rs13180 (IREB2), and rs8034191 (CHRNA 3/5), and four SNPs associated with lung function in a genome-wide association study of general population samples: rs2070600 (AGER), rs11134242 (ADCY2), rs4316710 (THSD4), and rs17096090 (INTS12). We tested for associations with severe COPD and COPD-related phenotypes, including lung function, smoking behavior, and body mass index. Subjects with COPD were older (average age 62 versus 58 years, P < 0.01), with more pack-years of smoking (45 versus 33 pack-years, P < 0.01). CHRNA3/5 (odds ratio [OR], 1.89; 95% confidence interval [CI], 1.5–2.4; P = 7.4 × 10−7), IREB2 (OR, 0.69; 95% CI, 0.5–0.9; P = 3.4 × 10−3), and ADCY2 (OR, 1.35; 95% CI, 1.1–1.7; P = 0.01) demonstrated significant associations with COPD. FAM13A (OR, 0.8; 95% CI, 0.7–1.0; P = 0.11) approached statistical significance. FAM13A and ADCY2 also demonstrated a significant association with lung function. Thus, in severe to very severe COPD, we demonstrate a replication of association between two SNPs previously associated with COPD (CHRNA3/5 and IREB2), as well as an association with COPD of one locus initially associated with lung function (ADCY2).
chronic obstructive pulmonary disease; genetic association analysis; lung function; smoking; nicotine addiction
COPD represents one of the leading causes of mortality in the general population. This study aimed at evaluating the relationship between airway hyperresponsiveness (AHR) and COPD and its relevance for clinical practice. We performed a MEDLINE search that yielded a total of 1919 articles. Eligible studies were defined as articles that addressed specific aspects of AHR in COPD, such as prevalence, pathogenesis, or prognosis. AHR appears to be present in at least one out of two individuals with COPD. The occurrence of AHR in COPD is influenced by multiple mechanisms, among which impairment of factors that oppose airway narrowing plays an important role. The main determinants of AHR are reduction in lung function and smoking status. We envision a dual role of AHR: in suspected COPD, specific determinants of AHR, such as reactivity and the plateau response, may help the physician to discriminate COPD from asthma; in definite COPD, AHR may be relevant for the prognosis. Indeed, AHR is an independent predictor of mortality in COPD patients. Smoking cessation has been shown to reduce AHR. Further studies are needed to elucidate whether this functional change is associated with improvement in lung function and respiratory symptoms.
bronchial hyperreactivity; airway hyperresponsiveness; bronchial provocation tests; COPD
Chronic obstructive pulmonary disease (COPD) is the 13th leading cause of burden of disease worldwide and is expected to become 5th by 2020. Biomass fuel combustion significantly contributes to COPD, although smoking is recognized as the most important risk factor. Rural women in developing countries bear the largest share of this burden resulting from chronic exposures to biomass fuel smoke. Although there is considerable strength of evidence for the association between COPD and biomass smoke exposure, limited information is available on the background prevalence of COPD in these populations.
This study was conducted to estimate the prevalence of COPD and its associated factors among non-smoking rural women in Tiruvallur district of Tamilnadu in Southern India.
This cross-sectional study was conducted among 900 non-smoking women aged above 30 years, from 45 rural villages of Tiruvallur district of Tamilnadu in Southern India in the period between January and May 2007. COPD assessments were done using a combination of clinical examination and spirometry. Logistic regression analysis was performed to examine the association between COPD and use of biomass for cooking. R software was used for statistical analysis.
The overall prevalence of COPD in this study was found to be 2.44% (95% CI: 1.43–3.45). COPD prevalence was higher in biomass fuel users than the clean fuel users 2.5 vs. 2%, (OR: 1.24; 95% CI: 0.36–6.64) and it was two times higher (3%) in women who spend >2 hours/day in the kitchen involved in cooking. Use of solid fuel was associated with higher risk for COPD, although no statistically significant results were obtained in this study.
The estimates generated in this study will contribute significantly to the growing database of available information on COPD prevalence in rural women. Moreover, with concomitant indoor air pollution measurements, it may be possible to increase the resolution of the association between biomass use and COPD prevalence and refine available attributable burden of disease estimates.
chronic obstructive pulmonary disease; prevalence; biomass fuel users; rural women; disease burden
Smoking cause airway and systemic inflammation and COPD patients present low grade inflammation in peripheral blood. However, data on the influence of smoking itself on systemic inflammation in COPD patients are scarce. This study investigated the association between inflammation, smoking status, and disease.
A cross-sectional analysis comparing 53 COPD ex-smokers, 24 COPD current smokers, 24 current smoker controls and 34 never-smoker controls was performed. Assessments included medical history, body composition, spirometry, and plasma concentration of tumor necrosis factor-alpha (TNF-α), interleukins (IL)-6, IL-8, and C-reactive protein (CRP).
Our exploratory analysis showed that serum TNF-α was higher in COPD current smokers [4.8(4.2-5.8)pg/mL] and in current smoker controls [4.8 (4.2-6.1) pg/mL] when compared to COPD ex-smokers [4.3 (3.9-4.9)pg/mL; p = 0.02] and to never-smoker controls [3.7 (3.4-4.0)pg/mL; p < 0.001]. Multiple regression results with and without adjustment for covariates were consistent with the hypothesis that TNF-α levels were associated with smoking status in both models (p < 0.001 and p < 0.001). IL-6 and CRP were significantly higher in COPD patients when compared to smoker and never-smoker controls and the multiple regression analysis confirmed the association of these mediators with disease, but not with smoking status (p < 0.001 and p < 0.001). IL-8 had only a borderline association with disease in both models (p = 0.069 and p = 0.053). No influence of disease severity, inhaled corticosteroid, fat-free mass (FFM) depletion and long term oxygen therapy (LTOT) use on systemic inflammation was found.
Smoking may influence TNF-α mediated systemic inflammation, which, in turn, may account for some of the benefits observed in patients with COPD who stop smoking.
In utero and/or childhood environmental tobacco smoke exposure is well known to adversely affect lung function and to depreciate child's health in many ways. Fewer studies have assessed the long-term effects on COPD development and disease severity in later adulthood.
COPD patients were interviewed using a structured questionnaire regarding their personal as well as the smoking habits of their parents. Data were compared with the disease history, e.g. COPD exacerbation rate, and their lung function data.
Between 2003 and 2004 COPD patients were recruited a) in a private practice specialized in pulmonary medicine (n = 133) and b) in a hospital (n = 158). 75% of their fathers and only 15.4 of all mothers smoked regularly. COPD patients from smoking mothers had lower FEV1 predicted than those raised in household without maternal smoking exposure: 39.4 ± 9.5% vs. 51.9 ± 6.0% (P = 0.037). Fathers had no effect on FEV1 regardless if they are smokers or non-smokers. Rate of severe exacerbations requiring hospitalization remained unaffected by parental second hand smoke exposure.
Maternal smoking negatively affects lung function of their offspring even in late adulthood when they develop COPD. It even aggravates the cumulative effect of active cigarette consumption. Clinical course of the COPD remained unaffected.
chronic obstructive pulmonary disease, COPD; second hand smoking
Immature bone marrow B cells are known to have longer CDR3 than mature peripheral B cells, and this genetic characteristic has been shown to correlate with autoreactivity in these early cells. B-cell Central tolerance eliminates these cells, but it is known that autoreactive B cells nevertheless appear commonly in healthy human blood. We examined over 7,300 Ig genes from Genbank, including those annotated by their discoverers as associated with autoreactivity, to determine the genetic correlates of autoreactivity in mature B cells.
We find differential biases in gene segment usage and higher mutation frequency in autoreactivity-associated Ig genes, but the CDR3 lengths do not differ between autoreactive and non-autoreactive Ig genes. The most striking genetic signature of autoreactivity is an increase in the proportion of N-nucleotides relative to germline-encoded nucleotides in CDR3 from autoreactive genes.
We hypothesize that peripheral autoreactivity results primarily from somatic mutation, and that the genetic correlates of autoreactivity in mature B-cells are not the same as those for autoreactivity in immature B cells. What is seen in mature autoreactive B cells are the correlates of autoreactive potential, not of autoreactivity per se. The autoreactive potential is higher for V(D)J rearrangements encoded to a large extent by N-nucleotides rather than by the gene segments that, we posit, have been selected in germline evolution for their suppression of autoreactive potential.
Caspase-dependent cleavage of antigens associated with apoptotic cells plays a prominent role in the generation of CD8+ T cell responses in various infectious diseases. We found that the emergence of a large population of autoreactive CD8+ T effector cells specific for apoptotic T cell-associated self-epitopes exceeds the antiviral responses in patients with acute hepatitis C virus infection. Importantly, they endow mixed polyfunctional type-1, type-2 and type-17 responses and correlate with the chronic progression of infection. This evolution is related to the selection of autoreactive CD8+ T cells with higher T cell receptor avidity, whereas those with lower avidity undergo prompt contraction in patients who clear infection. These findings demonstrate a previously undescribed strict link between the emergence of high frequencies of mixed autoreactive CD8+ T cells producing a broad array of cytokines (IFN-γ, IL-17, IL-4, IL-2…) and the progression toward chronic disease in a human model of acute infection.
The emergence of a large population of mixed polyfunctional (type-1, -2, -17) CD8+ T cell effector responses specific for apoptotic T cell-associated self-epitopes rather than the dysfunction or altered quality of virus-specific CD8+ T cells is associated with the progression toward chronic disease in the human model of acute HCV infection. The chronic evolution is associated with the selection of autoreactive CD8+ T cells with higher T cell receptor avidity, whereas those with lower avidity undergo prompt contraction, as seen in patients undergoing infection resolution. We suggest that these autoreactive responses are secondary to the viral persistence and can participate to the HCV-related immunopathology. This data has implications for the prognosis and therapy of infections undergoing chronic evolution.
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.
COPD; atherothrombosis; cardiovascular risk; mortality
Coke oven workers are regularly exposed to coke oven emissions (COE) and may be at risk of developing lung diseases. There is limited evidence for the link between exposure to COE and chronic obstructive pulmonary diseases (COPD). The aim of this study was to explore the dose‐response relationship between COE exposure and COPD and to assess the interaction with cigarette smoking.
Seven hundred and twelve coke oven workers and 211 controls were investigated in southern China. Benzene soluble fraction (BSF) concentrations as a surrogate of COE were measured in representative personal samples and the individual cumulative COE exposure level was quantitatively estimated. Detailed information on smoking habits and respiratory symptoms was collected and spirometric tests were performed.
The mean BSF levels at the top of two coking plants were 743.8 and 190.5 μg/m3, respectively, which exceed the OSHA standard (150 μg/m3). After adjusting for cigarette smoking and other risk factors, there was a significant dose‐dependent reduction in lung function and increased risks of chronic cough/phlegm and COPD in coke oven workers. The odds ratio for COPD was 5.80 (95% confidence interval 3.13 to 10.76) for high level cumulative COE exposure (⩾1714.0 μg/m3‐years) compared with controls. The interaction between COE exposure and smoking in COPD was significant. The risk of COPD in those with the highest cumulative exposure to COE and cigarette smoking was 58‐fold compared with non‐smokers not exposed to COE.
Long term exposure to COE increases the risk of an interaction between COPD and cigarette smoking.
chronic obstructive pulmonary disease; lung function; coke oven emissions; smoking
The identification of gene-by-environment interactions is important to understand the genetic basis of chronic obstructive pulmonary disease (COPD). Many COPD genetic association analyses assume a linear relationship between pack-years of smoking exposure and FEV1; however, this assumption has not been evaluated empirically in cohorts with a wide spectrum of COPD severity.
We examined the relationship between FEV1 and pack-years of smoking exposure in 4 large cohorts assembled for the purpose of identifying genetic associations with COPD. Using data from the Alpha-1 Antitrypsin Genetic Modifiers Study, we compared the accuracy and power of two different approaches to model smoking by performing a simulation study of a genetic variant with a range of gene-by-smoking interaction effects.
We identified nonlinear relationships between smoking and FEV1 in 4 large cohorts. We demonstrated that in most situations where the relationship between pack-years and FEV1 is nonlinear, a piecewise-linear approach to model smoking and gene-by-smoking interactions is preferable to the commonly used total pack-years approach. We applied the piecewise linear approach to a genetic association analysis of the PI*Z allele in the Norway case-control cohort and identified a potential PI*Z-by-smoking interaction (p=0.03 for FEV1 analysis, p= 0.01 for COPD susceptibility analysis).
In study samples with subjects having a wide range of COPD severity, a nonlinear relationship between pack-years of smoking and FEV1 is likely. In this setting, approaches that account for this nonlinearity can be more powerful and less-biased than the commonly-used approach of using total pack-years to model the smoking effect.
smoking; FEV1; gene-by-environment interaction; COPD; gene
Both chronic obstructive pulmonary disease (COPD) and tuberculosis (TB) primarily affect the lungs and are major causes of morbidity and mortality worldwide. COPD and TB have common risk factors such as smoking, low socioeconomic status and dysregulation of host defence functions. COPD is a prevalent co-morbid condition, especially in elderly with TB but in contrast to other diseases known to increase the risk of TB, relatively little is known about the specific relationship and impact from COPD on TB-incidence and mortality.
Methods and Findings
All individuals ≥40 years of age, discharged with a diagnosis of COPD from Swedish hospitals 1987–2003 were identified in the Swedish Inpatient Register (n = 115,867). Records were linked to the Swedish Tuberculosis Register 1989–2007 and the relative risk of active TB in patients with COPD compared to control subjects randomly selected from the general population (matched for sex, year of birth and county of residence) was estimated using Cox regression. The analyses were stratified by year of birth, sex and county of residence and adjusted for immigration status, socioeconomic status (SES) and inpatient co-morbidities previously known to increase the risk of TB. COPD patients had a three-fold increased hazard ratio (HR) of developing active TB (HR 3.0 (95% confidence interval 2.4 to 4.0)) that was mainly dependent on an increased risk of pulmonary TB. In addition, logistic regression estimates showed that COPD patients who developed active TB had a two-fold increased risk of death from all causes within first year after the TB diagnosis compared to the general population control subjects with TB (OR 2.2, 95% confidence interval 1.2 to 4.1).
This population-based study comprised of a large number of COPD patients shows that these patients have an increased risk of developing active TB compared to the general population. The results raise concerns that the increasing global burden of COPD will increase the incidence of active TB. The underlying contributory factors need to be disentangled in further studies.
Chronic obstructive pulmonary disease (COPD) is the most common chronic respiratory condition in adults and is characterized by progressive airflow limitation that is not fully reversible. The main etiological agents linked with COPD are cigarette smoking and biomass exposure but respiratory infection is believed to play a major role in the pathogenesis of both stable COPD and in acute exacerbations. Acute exacerbations are associated with more rapid decline in lung function and impaired quality of life and are the major causes of morbidity and mortality in COPD. Preventing exacerbations is a major therapeutic goal but currently available treatments for exacerbations are not very effective. Historically, bacteria were considered the main infective cause of exacerbations but with the development of new diagnostic techniques, respiratory viruses are also frequently detected in COPD exacerbations. This article aims to provide a state-of-the art review of current knowledge regarding the role of infection in COPD, highlight the areas of ongoing debate and controversy, and outline emerging technologies and therapies that will influence future diagnostic and therapeutic pathways in COPD.
COPD; exacerbations; bacteria; viruses
Chronic obstructive pulmonary disease (COPD) is one of the leading causes of morbidity and mortality in both industrialized and developing countries.
Cigarette smoking is the major risk factor for COPD. However, relevant information from the literature published within the last years, either on general population samples or on workplaces, indicate that about 15% of all cases of COPD is work-related.
Specific settings and agents are quoted which have been indicated or confirmed as linked to COPD. Coal miners, hard-rock miners, tunnel workers, concrete-manufacturing workers, nonmining industrial workers have been shown to be at highest risk for developing COPD.
Further evidence that occupational agents are capable of inducing COPD comes from experimental studies, particularly in animal models.
In conclusion, occupational exposure to dusts, chemicals, gases should be considered an established, or supported by good evidence, risk factor for developing COPD. The implications of this substantial occupational contribution to COPD must be considered in research planning, in public policy decision-making, and in clinical practice.
In this review we consider the therapeutic potential of targeting Akt for the treatment of COPD. Akt is a serine/threonine protein kinase that functions as a signaling intermediate linked to multiple signaling programs involved in survival, inflammation, and growth. Akt is closely associated with key membrane-bound receptors and represents a convergent integration point for multiple stimuli implicated in COPD pathogenesis. Persistent activation of Akt secondary to somatic mutations in regulatory oncogenes, such as PTEN, may explain why inflammation in COPD does not resolve when smoking is ceased. Akt is also implicated in the systemic manifestations of COPD such as skeletal muscle wasting and metabolic disturbances. Furthermore, targeting Akt may provide a useful means of limiting the severity and duration of disease exacerbations in COPD. As such, Akt represents a particularly attractive therapeutic target for the treatment of COPD. Interestingly, current knowledge suggests that both inhibitors and activators of Akt may be useful for treating different clinical subpopulations of COPD patients.
Akt; COPD; inflammation; apoptosis