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K F Rabe

Publications and source records attributed to K F Rabe.

At least 19 recordsLinked to original sources
PubMed2006

Interleukin-8 stimulates cell proliferation in non-small cell lung cancer through epidermal growth factor receptor transactivation.

Interleukin-8 (IL-8; CXCL8) is a cytokine of the CXC chemokine family that is involved in neutrophil recruitment and activation. In addition, IL-8 has been implicated in a wide variety of other processes, including angiogenesis and metastasis in lung cancer. Lung adenocarcinoma and muco-epidermoid carcinoma cells produce substantial amounts of IL-8, and express both CXCR1 and CXCR2 IL-8 receptors. We hypothesized that IL-8 stimulates proliferation of non-small cell lung cancer cells, involving transactivation of the epidermal growth factor receptor (EGFR). The EGFR plays a central role in regulating cell proliferation and it has been therefore implicated in lung cancer. Both EGFR ligands and transactivation of the receptor may lead to downstream signalling events, including mitogen-activated protein kinase (MAPK) activation. Transactivation of the EGFR has been shown to occur in response to ligands of various G-protein coupled receptors (GPCRs) and involves metalloproteinase-mediated release of membrane bound EGFR ligands. The aim of the present study was to investigate the effect of IL-8 on proliferation of lung adenocarcinoma and muco-epidermoid carcinoma cells, and to explore the mechanisms leading to this proliferation in two different non-small cell lung cancer cell lines (A549 and NCI-H292). In both NSCLC cell lines, we observed that IL-8 stimulates epithelial cell proliferation in a dose-dependent manner. The ability of IL-8 to increase cell proliferation was blocked both by an inhibitor of EGFR tyrosine kinase, by a specific anti-EGFR blocking antibody and by a panmetalloproteinase inhibitor. Similar results were obtained using the GPCR inhibitor pertussis toxin. Inhibition of the MAPK p42/44 (ERK1/2) also blocked the mitogenic effect of IL-8, while a p38 MAPK inhibitor did not affect IL-8-induced cell proliferation. These results suggest that IL-8 increases cell proliferation in NSCLC cell lines via transactivation of the EGFR and that this mechanism involves metalloproteinase activity.

Blotting, Western↗
PubMed2006

Deficient alpha-1-antitrypsin phenotypes and persistent airflow limitation in severe asthma.

BACKGROUND: Persistent airflow limitation is common among patients with severe asthma, but its pathogenesis has not been fully clarified. Severe alpha-1-antitrypsin (AAT) deficiency is a risk factor of chronic airflow limitation and emphysema, and partially deficient phenotypes have been associated with an accelerated decline in lung function. We hypothesized that partial deficiency of AAT (non-PiM AAT phenotype) is a risk factor of persistent airflow limitation in asthma. METHODS: In 122 patients with severe asthma (86 females; age (median (range)): 44.0 yr (18-75)) postbronchodilator FEV1 and FEV1/VC were measured and the AAT phenotype was determined. Persistent airflow limitation was defined as postbronchodilator FEV1 or FEV1/VC < 75% pred. with TLC > 75% pred. RESULTS: Six patients (4.9%) had a non-PiM phenotype (1 MF, 3 MS, 1 MZ and 1 SZ). Of the 58 patients with persistent airflow limitation only 1 patient (1.7%) had a non-PiM phenotype vs. 7.8% among the patients without persistent airflow limitation (P = 0.21). Postbronchodilator FEV1/VC (% pred.) was higher in the non-PiM patients than in the PiM patients (P = 0.02), the other lung function parameters were not different. Linear regression analysis showed no association between AAT phenotype and FEV1% predicted (P = 0.26). CONCLUSIONS: AAT heterozygoty does not seem to be an important risk factor of persistent airflow limitation in patients with asthma. Although confirmation by longitudinal follow-up studies with larger sample sizes is needed, these results suggest that routine assessment of the AAT phenotype is not indicated in asthmatic patients even if they exhibit fixed airflow limitation.

Adolescent↗
PubMed2006

Alveolar nitric oxide versus measures of peripheral airway dysfunction in severe asthma.

Alveolar nitric oxide (NO) is a measure of peripheral airway inflammation in asthma, potentially associated with disease severity. The relationship between alveolar NO and physiological tests of peripheral airway (dys)function has not been investigated. The present authors hypothesised that peripheral airway inflammation and dysfunction are inter-related and associated with asthma severity. Alveolar NO was compared between 17 patients with mild-to-moderate asthma and 14 patients with severe asthma and related to total lung capacity (TLC), residual volume (RV)/TLC, thoracic gas volume (FRC), slope of the single breath nitrogen washout curve (dN2), closing capacity (CC)/TLC and fall in forced vital capacity at the provocative concentration of methacholine causing a 20% fall in forced expiratory volume in one second. In patients with severe asthma, strong correlations were found between alveolar NO and RV/TLC % pred, FRC % pred, dN2, and CC/TLC. Patients with oral steroid-dependent asthma had higher alveolar NO levels (2.7 ppb) compared with the other patients with severe (0.6 ppb) and mild-to-moderate asthma (0.3 ppb). The present authors conclude that alveolar nitric oxide is closely related to parameters of peripheral airway dysfunction in patients with severe asthma, and that oral steroid-dependent asthmatics have more peripheral airway disease than nonsteroid-dependent asthmatics. This suggests that patients on chronic oral steroid treatment have more extensive disease and require additional anti-inflammatory treatment to better target the peripheral airways.

Adult↗
PubMed2006

Mechanisms of cell death induced by the neutrophil antimicrobial peptides alpha-defensins and LL-37.

OBJECTIVE: The aim of this study was to investigate the mechanisms of cell death mediated by the antimicrobial peptides neutrophil defensins (human neutrophil peptides 1-3 [HNP1-3]) and LL-37. MATERIALS AND METHODS: HNP1-3- and LL-37-mediated cell death was assessed in human lung epithelial cells and Jurkat T-cells in serum-free culture media. RESULTS: Both HNP1-3 and LL-37 induced cell death in Jurkat T-cells and A549 cells. HNP1-3 but not LL-37 induced caspase-3/-7 activity and caused cleavage of [ADP-ribose] polymerase (PARP) in Jurkat cells, while in A549 cells neither peptides induced caspase-3/-7 activation. Furthermore, both peptides increased mitochondrial cytochrome c release in A549 and Jurkat cells. Our observation that over-expression of the anti-apoptotic protein Bcl-2 in Jurkat cells did not affect HNP1-3- or LL-37-induced cell death indicates that antimicrobial peptide-induced cytochrome c release is not involved in peptide-induced cell death. Finally, in A549 cells and in primary bronchial epithelial cells, both HNP1-3 and LL-37 induced DNA breaks as demonstrated by increased TUNEL labelling. CONCLUSIONS: The results from this study suggest that the antimicrobial peptides HNP1-3 and LL-37 induce cell death, which is associated with mitochondrial injury and mediated via different intracellular pathways.

Anti-Infective Agents↗
PubMed2006

[Combination of asthma and COPD: more frequent as considered to be?].

Evidence-based national and international guidelines are largely aimed to guide in the diagnosis and treatment of asthma or COPD, but none addresses sufficiently mixed disease states of both disorders, which are ill-defined but very common in the daily routine clinic. This is a consensus report of a workshop on mixed disease. Asthma is characterized by a classical clinical history and physical exam, reversible airflow limitation and a high degree of bronchial hyperresponsiveness. In contrast, history (mostly smoker) and findings in typical COPD are different: COPD patients have little if any bronchial hyperresponsiveness and reversibility of the airflow limitation, respectively. However, beyond the full reversible airflow limitation which excludes COPD or mixed disease, none of these criteria are fully discriminatory. Patients with some of the characteristics of both diseases should be classified as mixed disease. A definitive diagnosis however, should only be assigned in a dynamic process. Once diagnosed the patient should be continuously re-evaluated according to the strength of the diagnosis, since the consequent treatment is important: COPD patients with asthmatic phenotype need early inhaled corticosteroids, even if their FEV1 > 50 %. Moreover, allergen avoidance can be indicated. On the other hand, asthma patients with COPD phenotype could benefit from anticholinergics or--if indicated--pulmonary rehabilitation. Mixed disease should be diagnosed as the coexistence of two distinct entities, i. e. asthma (allergic or intrinsic asthma, whichever is appropriate) and COPD.

Asthma↗
PubMed2006

[Clinical significance of gastrooesophageal reflux in asthma].

In clinical practice, gastrooesophageal reflux (GER) and bronchial asthma often coincide. In the case of sufficient asthma control, the asthma does not need to be taken into account when treatment of GER is being evaluated. In patients with symptomatic asthma despite adequate antiasthmatic treatment, a possible causal relationship between GER and the poor responsiveness to asthma therapy has to be considered. An algorithm to guide the diagnostic and therapeutic steps in such cases is presented.

Asthma↗
PubMed2006

Poor asthma control in children: evidence from epidemiological surveys and implications for clinical practice.

The objectives of this study is to compile current knowledge about asthma control in children in relation to goals proposed in international guidelines, to elucidate the factors associated with insufficient asthma control and to address the implications for clinical practice. Review of recent worldwide large population epidemiological surveys and clinical asthma studies of more than 20,000 children are the methods used in this study. The studies report high frequencies of sleep disturbances, emergency visits, school absence and limitations of physical activity due to asthma. Only a small percentage of children with asthma reach the goals of good asthma control set out by Global Initiative for Asthma (GINA). There is evidence of underuse of inhaled corticosteroids even in children with moderate or severe persistent asthma and over-reliance on short-acting beta(2)-agonist rescue medication. Both parents and physicians generally overestimate asthma control and have low expectations about the level of achievable control. Many children with asthma are not being managed in accordance with guideline recommendations, and asthma management practices vary widely between countries. Asthma control falls short of guideline recommendations in large proportions of children with asthma worldwide. Simple methods for assessing asthma control in clinical practice are needed. Treatment goals based on raised expectations should be established in partnership with the asthmatic child and the parents. Effective anti-inflammatory treatment should be used more frequently, and patients should be reviewed regularly.

Adolescent↗
PubMed2006

The effect of a single inhaled dose of a VLA-4 antagonist on allergen-induced airway responses and airway inflammation in patients with asthma.

Adhesion molecule very late antigen-4 (VLA-4) is implicated in the recruitment and activation of inflammatory cells in asthma, including eosinophils, T cells and mast cells. VLA-4 antagonists have been proposed as a new anti-inflammatory treatment modality for asthma. Therefore, we investigated whether a single inhaled dose of VLA-4 antagonist GW559090X could protect against allergen-induced changes in airway responses and airway inflammation in patients with asthma. We performed a randomized, double-blind, three-way crossover study with single inhaled doses of 3 mg of GW559090X, 500 microg of fluticasone propionate (FP) or placebo in 15 patients with mild intermittent asthma, controlled with short-acting beta(2)-agonists only. All patients developed a late asthmatic response (LAR) after allergen inhalation during screening. Study medication was administered 30 min prior to allergen challenge. Pre-dose and 24 h post-dose PC20 methacholine and levels of exhaled nitric oxide (eNO) were determined. At the given dose, VLA-4 antagonist GW559090X did not attenuate the early asthmatic response (EAR) when compared with placebo: mean AUC0-2 h(+/-SEM) (%fall h): 27.2+/-3.7 and 21.9+/-3.0 respectively (P=0.33); nor the LAR: mean AUC3-8 h(+/-SEM) (%fall h): 98.8+/-12.9 and 94.8+/-6.8 respectively (P=0.84). However, pretreatment with FP did attenuate both EAR and LAR when compared with placebo: mean AUC0-2 h11.6+/-3.3 (P=0.024) and mean AUC3-8 h 6.3+/-7.6 (P<0.001). None of these treatments had an effect on allergen-induced changes in airway hyper-responsiveness or eNO levels. These findings suggest that VLA-4 may not play a major role in allergen-induced airway responses and inflammation in asthma.

Administration, Inhalation↗
PubMed2006

Transbronchial and transoesophageal (ultrasound-guided) needle aspirations for the analysis of mediastinal lesions.

A tissue diagnosis of mediastinal nodes is frequently needed for accurate lung cancer staging as well as the assessment of mediastinal masses. Transbronchial needle aspiration (TBNA) is a safe procedure that is performed during routine bronchoscopy. Provided mediastinal metastases are confirmed, TBNA has a high impact on patient management. Unfortunately, TBNA remains underused in current daily practice, mainly due to the lack of real-time needle visualisation. The introduction of echo-endoscopes has overcome this problem. Endobronchial ultrasound-guided TBNA (EBUS-TBNA) allows real-time controlled tissue sampling of paratracheal, subcarinal and hilar lymph nodes. Mediastinal lymph nodes located adjacent to the oesophagus can be assessed by transoesophageal ultrasound-guided fine needle aspiration (EUS-FNA). Owing to the complementary reach of EBUS-TBNA and EUS-FNA in assessing different regions of the mediastinum, recent studies suggest that complete and accurate mediastinal staging can be achieved by the combination of both procedures. It is expected that implementation of minimally invasive endoscopic methods of endobronchial ultrasound-guided transbronchial needle aspiration and transoesophageal ultrasound-guided fine needle aspiration will reduce the need for surgical staging of lung cancer significantly.

Biopsy, Fine-Needle↗
PubMed2006

Variability of bronchial inflammation in chronic obstructive pulmonary disease: implications for study design.

There is variability in the distribution of inflammatory cells in bronchial tissue in chronic obstructive pulmonary disease (COPD). Better strategies for biopsy sampling of the airway mucosa may improve the capacity to show a difference between study populations where variability in distribution exists. The current authors have examined sources of biological variability in the quantification of inflammatory cells in endobronchial biopsies using immunostained samples taken from 51 subjects with COPD, with a mean forced expiratory volume in one second of 1.71 L, 55% predicted. The distribution of variance contributed by different sources was similar for different inflammatory cell types. For CD8+ cells, a key inflammatory cell in COPD, the largest contribution to intra-subject variability (39%) was time (i.e. 10 weeks between biopsies of placebo-treated subjects), followed by airway generation (23%), biopsy (2.5%), zone (within section; 1.4%) and section (0.4%). Power calculations demonstrated that examining one section from one biopsy, from each of two airway generations, would require a sample size of 32 subjects per group to show a difference of one doubling or halving in CD8+ cells, compared with 47 subjects per group if only one airway generation was sampled. Therefore, biopsies from more than one airway generation should be examined in order to maximise statistical power to detect a difference between study groups.

Adult↗
PubMed2005

Bronchial matrix and inflammation respond to inhaled steroids despite ongoing allergen exposure in asthma.

BACKGROUND: Inflammatory and structural changes of the airway mucosa are chronic features of asthma. The mechanisms underlying these changes and their modulation by steroid prophylaxis have not been clarified. OBJECTIVE: We postulated that asymptomatic ongoing allergen exposure could drive airway inflammation as well as changes in the extracellular matrix (ECM), and that inhaled steroids could prevent this. METHODS: Therefore, we exposed patients with mild asthma to 2 weeks of repeated low-dose allergen, with concomitant inhaled steroid or placebo treatment. Bronchial biopsies, which were taken before and after this exposure, were stained and digitally analysed. The ECM proteins in asthmatics were also compared with a normal control group. RESULTS: Low-dose allergen exposure alone resulted in a significant increase of bronchial epithelial macrophages. Despite ongoing allergen exposure, inhaled steroids reduced the numbers of mucosal eosinophils, neutrophils and T lymphocytes. At baseline, the mean density of the proteoglycans (PGS) biglycan and decorin were, respectively, higher and lower in the bronchial mucosa of asthmatics as compared with normal controls. Steroid treatment, during allergen exposure, increased the mean density of the PGS biglycan and versican. CONCLUSION: We conclude that chronic allergen exposure induces inflammatory changes in the bronchial mucosa. Despite ongoing allergen exposure, steroid treatment decreases mucosal inflammatory cells while altering PG density. The latter observation highlights the need to examine steroid-induced changes closely in the airway structure in patients with asthma.

Administration, Inhalation↗
PubMed2005

Small airways function and molecular markers in exhaled air in mild asthma.

BACKGROUND: Several studies suggest that the periphery of the lung is the major site of inflammation in asthma. Fractional exhaled nitric oxide (Feno) and 8-isoprostane have been proposed as biomarkers of inflammation and oxidative stress. We therefore hypothesised that small airway dysfunction in asthma is of inflammatory origin that can be detected by molecular markers in exhaled air. To test this hypothesis, we examined the relationship of Feno and 8-isoprostane in exhaled air with small airways function as assessed by the single breath nitrogen test. METHODS: Sixteen patients (14 women) with mild atopic asthma (forced expiratory volume in 1 second >80% predicted) of mean (SD) age 23.0 (5.5) years participated in a cross sectional study. Feno was recorded by chemiluminescence and 8-isoprostane was measured by ELISA in concentrated exhaled breath condensate. The slope of phase III (deltaN2) and the closing volume (CV) were assessed from the single breath washout curve. RESULTS: The median Feno level was 30.4 ppb (range 10.1-82.8), the median 8-isoprostane concentration in exhaled breath condensate was 2.2 pg/ml (range 1.6-2.7), and the mean (SD) deltaN2 value was 1.1 (0.4)% N2/l. Feno was positively associated with deltaN2 (r(s) = 0.54, p = 0.032) while 8-isoprostane was inversely correlated with FEV1% predicted (rs= -0.58; p = 0.017) and CV as a percentage of vital capacity (rs= 0.58; p = 0.019). CONCLUSIONS: Feno and 8-isoprostane in exhaled air are associated with small airways function in mild asthma. This suggests that these markers reflect small airway inflammation and favours a role for them as disease markers that is complementary to spirometry in the monitoring of patients with asthma.

Adult↗
PubMed2005

Risk factors of frequent exacerbations in difficult-to-treat asthma.

Recurrent exacerbations are a major cause of morbidity and medical expenditure in patients with asthma. Various exogenous and endogenous factors are thought to influence the level of asthma control, but systematical data on the involvement of these factors in the recurrence of asthma exacerbations are scarce. In this study, 13 clinical and environmental factors potentially associated with recurrent exacerbations were investigated in 136 patients with difficult-to-treat asthma. Patients with more than three severe exacerbations (n = 39) in the previous year were compared with those with only one exacerbation per year (n = 24). A systematic diagnostic protocol was used to assess 13 potential risk factors. Factors significantly associated with frequent exacerbations included: severe nasal sinus disease (adjusted odds ratio (OR) 3.7); gastro-oesophageal reflux (OR 4.9); recurrent respiratory infections (OR 6.9); psychological dysfunctioning (OR 10.8); and obstructive sleep apnoea (OR 3.4). Severe chronic sinus disease and psychological dysfunctioning were the only independently associated factors (adjusted OR 5.5 and 11.7, respectively). All patients with frequent exacerbations exhibited at least one of these five factors, whilst 52% showed three or more factors. In conclusion, the results show that recurrent exacerbations in asthma are associated with specific co-morbid factors that are easy to detect and that are treatable. Therapeutic interventions aimed at correcting these factors are likely to reduce morbidity and medical expenditure in these patients.

Adolescent↗