Mieke A. Dentener

Systemic anti-inflammatory mediators in COPD: increase in soluble interleukin 1 receptor II during treatment of exacerbations

BACKGROUND The aim of this study was to test the hypothesis that the chronic inflammatory process present in chronic obstructive pulmonary disease (COPD) is due to a defective endogenous anti-inflammatory mechanism. METHODS Systemic levels of the anti-inflammatory mediators soluble interleukin 1 receptor II (sIL-1RII), soluble tumour necrosis factor receptor p55 (sTNF-R55) and sTNF-R75, and of C reactive protein (CRP) and lipopolysaccharide binding protein (LBP) were analysed in 55 patients with stable COPD (median forced expiratory volume in one second (FEV1) 34% predicted (range 15–78)) and compared with levels in 23 control subjects. In addition, changes in these mediators were studied in 13 patients with COPD (median FEV1 34% predicted (range 19–51)) during the first 7 days in hospital with an exacerbation of the disease. RESULTS Patients with stable COPD were characterised by a systemic inflammatory process indicated by an increased leucocyte count (7.2 (4.7–16.4)v 4.8 (3.5–8.3) × 109/l), raised levels of CRP (11.8 (1.1–75.0) v 4.1 (0.6–75.0) μg/ml) and LBP (45.6 (8.1–200.0)v 27.9 (14.1–71.5) μg/ml), and moderate increases in both sTNF-Rs. In contrast, the sIL-1RII level did not differ between patients and controls (4.53 (2.09–7.60)v 4.63 (3.80–5.93) ng/ml). During treatment of disease exacerbations, systemic levels of both CRP (at day 3) and LBP (at day 7) were significantly reduced compared with day 1, whereas sIL-1RII levels increased. CONCLUSIONS These data suggest an imbalance in systemic levels of pro- and anti-inflammatory mediators in patients with stable COPD. The increase in the anti-inflammatory mediator sIL-1RII during treatment of exacerbations may contribute to the clinical improvement.

Systemic and local inflammation in asthma and chronic obstructive pulmonary disease: is there a connection?

Increasing evidence indicates that chronic obstructive pulmonary disease (COPD) and probably asthma are associated with low-grade systemic inflammatory changes. In patients with COPD, systemic inflammation is considered a key factor in the pathogenesis of the multicomponent disease manifestations. Spillover of inflammatory mediators into the circulation is generally considered to be the source of this systemic inflammation. Despite this attractive hypothesis, the nature of systemic inflammation in COPD and asthma remains unclear. Available scientific data challenge the spill-over hypothesis. Interventions with biologicals such as TNF-alpha do not modify local or systemic inflammation in these inflammatory respiratory diseases. Adipose tissue-mediated inflammation is discussed as a connecting link of systemic inflammation in asthma and COPD.

Enhanced levels of hyaluronan in lungs of patients with COPD: relationship with lung function and local inflammation

Background: Chronic inflammation and airway remodelling are characteristics of chronic obstructive pulmonary disease (COPD). Hyaluronan (HA) is an extracellular matrix compound with proinflammatory activity. HA levels in induced sputum from patients with COPD were measured and related to local inflammation. The expression of hyaluronan synthase 2 (HAS2) and hyaluronidase 2 (HYAL2) was analysed in lung tissue. Methods: Sputum was obtained from 18 patients with COPD (forced expiratory volume in 1 second (FEV1) 62% predicted (range 20–76)) and 14 healthy smokers. HA and inflammatory markers were measured using ELISA assays. Lung sections were obtained from five patients with severe COPD (FEV1 <30%) and from five smokers, and mRNA levels of HAS2 and HYAL2 were analysed by polymerase chain reaction. Results: HA levels were significantly higher in the sputum from patients with COPD than controls. The COPD population appeared to consist of two subpopulations with either high or moderate HA levels. The subgroup of patients with high HA levels had lower FEV1 than the moderate HA group. In addition, neutrophil influx and levels of interleukin-8, and the soluble tumour necrosis factor receptors R55 and R75 were significantly higher in patients with high HA levels than in those with moderate HA levels and controls. Semiquantitative analysis revealed enhanced expression of HYAL2 in lung tissue of patients with severe COPD compared with control subjects. Conclusion: These data indicate a relationship between HA levels, local inflammation and severity of disease, and suggest enhanced breakdown of HA in the lungs of patients with COPD.

Enhanced pulmonary leptin expression in patients with severe COPD and asymptomatic smokers

Background: Chronic obstructive pulmonary disease (COPD) is characterised by an abnormal inflammatory reaction of the lungs involving activation of epithelial cells. Leptin is a pleiotropic cytokine important in the regulation of immune responses via its functional receptor Ob-Rb. This study was undertaken to test the hypothesis that severe COPD is associated with increased leptin expression in epithelial cells. Methods: Immunohistochemistry for leptin was performed on peripheral lung specimens from 20 patients with COPD (GOLD stage 4), 14 asymptomatic ex-smokers and 13 never smokers. Leptin and Ob-Rb mRNA expression were determined by rtPCR in cultured primary bronchial epithelial cells and primary type II pneumocytes. NCI-H292 and A549 cell lines were used to study functional activation of leptin signalling. Results: Leptin immunoreactivity in lung tissue was observed in bronchial epithelial cells, type II pneumocytes, macrophages (tissue/alveolar) and interstitial lymphocytic infiltrates. rtPCR analysis confirmed pulmonary leptin and Ob-Rb mRNA expression in primary bronchial epithelial cells and pneumocytes. Leptin-expressing bronchial epithelial cells and alveolar macrophages were markedly higher in patients with severe COPD and ex-smokers than in never smokers (p<0.02). Exposure of cultured primary bronchial epithelial cells to smoke resulted in increased expression of both leptin and Ob-Rb (p<0.05). Leptin induced phosphorylation of STAT3 in both NCI-H292 and A549 cells. Conclusions: Leptin expression is increased in bronchial epithelial cells and alveolar macrophages of ex-smokers with or without severe COPD compared with never smokers. A functional leptin signalling pathway is present in lung epithelial cells.

Effect of infliximab on local and systemic inflammation in chronic obstructive pulmonary disease: A pilot study

Background: Chronic obstructive pulmonary disease (COPD) with cachexia is characterized by inflammation reflected by increased levels of tumor necrosis factor-α (TNF-α). Objectives: In this study, infliximab, an anti-TNF-α antibody, was evaluated for its effects on systemic (plasma) and local (exhaled breath condensate, EBC) inflammation in cachectic patients with COPD. Also, baseline levels of new inflammatory markers were compared to control subjects. Methods: Sixteen cachectic patients with moderate to severe COPD were examined for inflammatory status at baseline and compared to 25 control subjects. Patients were randomized (1:1) to receive infliximab (5 mg/kg) or placebo at weeks 0, 2 and 6. Patients were evaluated at weeks 8 and 12 and followed through week 26. Results: EBC analysis revealed increased levels of several novel inflammatory markers, including macrophage migration inhibitory factor, IL-12, RANTES and sICAM-1, in patients with COPD compared to controls. EBC levels of inflammatory markers were unchanged in patients receiving infliximab. In addition, systemic levels of acute-phase proteins (C-reactive protein, fibrinogen and lipopolysaccharide-binding protein), IL-6 and soluble TNF receptor (sTNFR) 55 had not changed at weeks 8 or 12. Small increases in circulating levels of sTNFR75, myeloperoxidase and Clara cell protein 16 were seen at week 8, but not at week 12. Conclusions: In this small study, infliximab did not produce an observable decrease in local inflammation in cachectic patients with COPD and had minor effects on systemic inflammation. The detection of new inflammatory markers in EBC can help to further characterize local inflammatory processes in COPD.

IL6 and CRP haplotypes are associated with COPD risk and systemic inflammation: a case-control study.

BackgroundElevated circulating levels of C-reactive protein (CRP), interleukin (IL)-6 and fibrinogen (FG) have been repeatedly associated with many adverse outcomes in patients with chronic obstructive pulmonary disease (COPD). To date, it remains unclear whether and to what extent systemic inflammation is primary or secondary in the pathogenesis of COPD.The aim of this study was to examine the association between haplotypes of CRP, IL6 and FGB genes, systemic inflammation, COPD risk and COPD-related phenotypes (respiratory impairment, exercise capacity and body composition).MethodsEighteen SNPs in three genes, representing optimal haplotype-tagging sets, were genotyped in 355 COPD patients and 195 healthy smokers. Plasma levels of CRP, IL-6 and FG were measured in the total study group. Differences in haplotype distributions were tested using the global and haplotype-specific statistics.ResultsRaised plasma levels of CRP, IL-6 and fibrinogen were demonstrated in COPD patients. However, COPD population was very heterogeneous: about 40% of patients had no evidence of systemic inflammation (CRP < 3 mg/uL or no inflammatory markers in their top quartile). Global test for haplotype effect indicated association of CRP gene and CRP plasma levels (P = 0.0004) and IL6 gene and COPD (P = 0.003). Subsequent analysis has shown that IL6 haplotype H2, associated with an increased COPD risk (p = 0.004, OR = 4.82; 1.64 to 4.18), was also associated with very low CRP levels (p = 0.0005). None of the genes were associated with COPD-related phenotypes.ConclusionOur findings suggest that common genetic variation in CRP and IL6 genes may contribute to heterogeneity of COPD population associated with systemic inflammation.

Tumor Necrosis Factor-α +489G/A gene polymorphism is associated with chronic obstructive pulmonary disease

BackgroundChronic obstructive pulmonary disease (COPD) is characterized by a chronic inflammatory process, in which the pro-inflammatory cytokine Tumor Necrosis Factor (TNF)-α is considered to play a role. In the present study the putative involvement of TNF-α gene polymorphisms in pathogenesis of COPD was studied by analysis of four TNF-α gene polymorphisms in a Caucasian COPD population.MethodsTNF-α gene polymorphisms at positions -376G/A, -308G/A, -238G/A, and +489G/A were examined in 169 Dutch COPD patients, who had a mean forced expiratory volume in one second (FEV1) of 37 ± 13%, and compared with a Dutch population control group of 358 subjects.ResultsThe data showed that the TNF-α +489G/A genotype frequency tended to be different in COPD patients as compared to population controls, which was due to an enhanced frequency of the GA genotype. In line herewith, carriership of the minor allele was associated with enhanced risk of development of COPD (odds ratio = 1.9, p = 0.009). The other TNF-α gene polymorphisms studied revealed no discrimination between patients and controls. No differences in the examined four TNF-α polymorphisms were found between subtypes of COPD, which were stratified for the presence of radiological emphysema. However, comparison of the COPD subtypes with controls showed a significant difference in the TNF-α +489G/A genotype in patients without radiological emphysema (χ2-test: p < 0.025 [Bonferroni adjusted]), while no differences between COPD patients with radiological emphysema and controls were observed.ConclusionBased on the reported data, it is concluded that COPD, and especially a subgroup of COPD patients without radiological emphysema, is associated with TNF-α +489G/A gene polymorphism.

Systemic Inflammation in COPD: Is Genetic Susceptibility a Key Factor?

COPD is a multicomponent disease characterized by abnormal inflammatory response of the lungs to noxious particles that is accompanied by systemic effects like weight loss, muscle wasting, reduced functional capacity and impaired health status. A persistent low-grade systemic inflammatory response reflected by enhanced levels of acute phase proteins like C-reactive protein (CRP) and pro-inflammatory cytokines such as tumor necrosis factor (TNF)-α, is present in part of the COPD population. The production of inflammatory proteins is partly genetically determined. Several studies have shown that polymorphisms within genes coding for these inflammatory mediators may modulate systemic inflammatory responses. Among all of these genes, the TNF family (TNF-α, lymphotoxin (LT)-α and their receptors TNF-R55 and TNF-R75), interleukin (IL)-6 and CRP gene polymorphisms are the most prominent candidates. However, large carefully designed studies in well-characterized COPD cohorts are required to unravel the exact role of genetic background in the systemic component of this disease.

Enhanced deposition of low-molecular-weight hyaluronan in lungs of cigarette smoke-exposed mice

Chronic obstructive pulmonary disease (COPD) is characterized by infiltration of inflammatory cells, destruction of lung parenchyma, and airway wall remodeling. Hyaluronan (HA) is a component of the extracellular matrix, and low-molecular-weight (LMW) HA fragments have proinflammatory capacities. We evaluated the presence of HA in alveolar and airway walls of C57BL/6 mice that were exposed to air or cigarette smoke (CS) for 4 weeks (subacute) or 24 weeks (chronic). We measured deposition of the extracellular matrix proteins collagen and fibronectin in airway walls and determined the molecular weight of HA purified from lung tissue. In addition, we studied the expression of HA-modulating genes by RT-PCR. HA staining in alveolar walls was significantly enhanced upon chronic CS exposure, whereas HA levels in the airway walls were already significantly higher upon subacute CS exposure and remained elevated upon chronic CS exposure. This differed from the deposition of collagen and fibronectin, which are only elevated at the chronic time point. In lungs of CS-exposed mice, the molecular weight of HA clearly shifted toward more LMW HA fragments. CS exposure significantly increased the mRNA expression of the HA synthase gene Has3 in total lung tissue, whereas the expression of Has1 was decreased. These in vivo studies in an experimental model of COPD show that CS exposure leads to enhanced deposition of (mostly LMW) HA in alveolar and bronchial walls by altering the expression of HA-modulating enzymes. This may contribute to airway wall remodeling and pulmonary inflammation in COPD.

Gender differences in the adipose secretome system in chronic obstructive pulmonary disease (COPD): A pivotal role of leptin

BACKGROUND COPD is characterized by a multi-component character involving a state of low-grade systemic inflammation and an increased prevalence of cardiovascular co-morbidity. The role of circulating leptin and other adipokines in the involvement of the systemic inflammation in COPD is only studied scarcely. OBJECTIVE To investigate gender related differences in the adipokine metabolism in relation to systemic inflammatory biomarkers in clinically stable subjects with COPD. METHODS In total, 91 clinically stable COPD patients and 35 healthy control subjects, matched for body mass index (BMI) with the COPD subjects, were included. Lung function measurement and body composition were performed in patients with COPD. In the total group, plasma concentration of the adipokines (leptin, adiponectin and resistin) and systemic inflammatory biomarkers C-reactive protein (CRP), interleukin 6 (IL-6), tumor necrosis factor α (TNFα), and its soluble receptors 55 and 75 (sTNFα-R55, R75) were analyzed. RESULTS The COPD group was characterized by increased levels of CRP, IL-6 and leptin. Plasma adiponectin and resistin concentrations were not different between the COPD and the control group. Within the COPD group, there was a significant interaction between gender and BMI on the leptin/fat mass ratio. In COPD women, a significant correlation between leptin and CRP was present. CONCLUSIONS In men with clinically stable COPD, leptin, adiponectin and resistin appear to be physiologically regulated, while in women, leptin metabolism is altered. Leptin secretion is increased in COPD women when compared to healthy women and compared to COPD men, and to a greater extent in overweight women with COPD.