Pseudomonas aeruginosa is a persistent pathogen in the airways of patients with cystic fibrosis or bronchiectasis from other causes and appears to have evolved strategies to survive the inflammatory response of the host. We hypothesized that the secreted hemolytic phospholipase C (PLC) of P. aeruginosa (PlcHR) would decrease neutrophil respiratory burst activity. We found that while intact wild-type P. aeruginosa cells stimulated moderate respiratory burst activity from human neutrophils, an isogenic mutant pseudomonas (DeltaHR strain) containing a targeted deletion of the plcHR operon induced a much more robust oxidative burst from neutrophils. In contrast, a second pseudomonas mutant (DeltaN) containing a disruption in the gene encoding the nonhemolytic PLC (PlcN) was not different from the wild type in stimulating neutrophil O2.- production. Readdition of purified PlcHR to the DeltaHR strain suppressed neutrophil O2.- production to levels stimulated by wild-type bacteria. Interestingly, purified PlcHR decreased phorbol myristate acetate (PMA)- but not formyl methionyl-leucyl-proline (fMLP)-induced respiratory burst activity, suggesting interference by PlcHR with a protein kinase C (PKC)-specific signaling pathway. Accordingly, the PKC inhibitor bisindolylmaleimide inhibited the oxidative burst induced by either PMA or intact pseudomonas, but not by fMLP, whereas the p38 kinase inhibitor SB-203580 fully inhibited the respiratory burst induced by fMLP or the PlcHR-replete wild-type bacteria, but not PMA or the PlcHR-deficient DeltaHR bacterial mutant. We conclude that expression of PlcHR by P. aeruginosa suppresses bacterium-induced neutrophil respiratory burst by interfering with a PKC-dependent, non-p38 kinase-dependent pathway. (+info)
Nitric oxide-induced potentiation of the killing of Burkholderia cepacia by reactive oxygen species: implications for cystic fibrosis.
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Burkholderia (formerly Pseudomonas) cepacia has emerged as an important pulmonary pathogen in cystic fibrosis, and survives within the lung despite a vigorous neutrophil-dominated immune response. Nitric oxide (NO) contributes to the antimicrobial activity of reactive oxygen species in the normal lung, but recent evidence suggests that inducible NO synthase is not expressed in the airway epithelial cells of cystic fibrosis (CF) patients. This may explain the failure of the neutrophil response to eliminate B. cepacia. To test this hypothesis, the present study examined the combined effect of NO, superoxide and H2O2 against B. cepacia. There was no killing of a highly transmissible strain by either superoxide or NO alone, but their combination reduced the bacterial count by >1000-fold over 75 min. This bactericidal activity was not sensitive to addition of superoxide dismutase, but was abrogated completely by catalase, suggesting that NO and hydrogen peroxide were the bactericidal mediators. Increased killing by NO in combination with H2O2 was seen for seven of a further 11 strains examined. The lack of NO in the lungs of CF patients may contribute to the survival of B. cepacia. (+info)
Construct and longitudinal validity of a modified Huang clinical scoring system in adult cystic fibrosis patients.
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This study reports on the evaluation of a modified Huang scoring system in adult cystic fibrosis patients for construct and longitudinal validity. Two studies were performed. In the first study, the scoring system was applied to 59 adult cystic fibrosis patients prospectively followed at the Montreal Chest Institute. The total score and all the subscores distinguished between patients with the expected mild degree of disease severity seen in patients colonized with only Staphylococcus aureus, compared to the more advanced disease severity seen in patients colonized with Pseudomonas aeruginosa or multiple resistant pseudomonads. The relationship between disease severity assessed by forced expiratory volume in one second per cent predicted and the nonpulmonary function subscores was significant and linear (for the radiological subscore, r2=0.694, p<0.0001) and curvilinear (for the clinical and complications subscores, r2=0.622, p=0.0192 and r2=0.508, p=0.0009 respectively). In the second study, 20 patients retrospectively recorded were added to the prospective group. There was a good association between changes in nonpulmonary function subscores and changes in spirometry over a mean follow-up period of 779+/-204 days, at all levels of disease severity. The contribution of changes in clinical and complications subscores to the changes in total score became progressively more significant with more advanced disease severity. In conclusion, significant evidence for the construct validity of the scoring system as a discriminative instrument and for the longitudinal validity as an evaluative instrument was demonstrated. It may prove of value in assessing outcome of therapeutic interventions in clinical trials in patients with cystic fibrosis. (+info)
Treatment of pulmonary exacerbations of cystic fibrosis leads to improved antioxidant status.
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Many cystic fibrosis (CF) patients have increased circulating levels of oxidation products and/or decreased antioxidant status. This study investigated whether treatment of pulmonary exacerbations decreased oxidative stress in CF patients. Seventeen adult patients were studied at the beginning and end of treatment with intravenous antibiotics. Plasma concentrations of the antioxidants ascorbic acid, alpha-tocopherol, uric acid and total reduced thiols, together with plasma retinol, lipid hydroperoxides, malondialdehyde and protein carbonyl levels were determined. Median (interquartile range) pretreatment and post-treatment levels were compared using the Wilcoxon signed rank test. Clinical resolution was reflected by improved spirometry. Significant increases were observed in plasma ascorbic acid (pre 30.4 (15.7-38.6) microM, post 35.2 (27.3-49.6) microM), alpha-tocopherol (pre 19.7 (13.6-25.2) microM, post 25.2 (19.3-31.6) microM) and retinol (pre 1.9 (1.5-2.5) microM, post 2.7 (1.7-3.5) microM). No change in plasma total reduced thiols occurred following treatment (pre 409 (366-420) microM, post 392 (366-423) microM), whereas uric acid fell with treatment (pre 307 (274-394) microM, post 260 (216-317) microM). Neither plasma protein carbonyls or malondialdehyde levels altered with treatment (protein carbonyls pre 0.47 (0.28-1.27), post 0.67 (0.42-0.83) nM x mg protein(-1); malondialdehyde pre 0.75 (0.53-1.18), post 0.84 (0.65-1.15) microM). Lipid hydroperoxides levels did decrease following treatment (53 (18-85) versus 17 (10-55) nM). This study demonstrated that treatment of infective exacerbations resulted in increased plasma levels of some antioxidant vitamins. No immediate change in plasma protein oxidation was observed, but lipid oxidation was decreased. (+info)
Reduction in the adherence of Pseudomonas aeruginosa to native cystic fibrosis epithelium with anti-asialoGM1 antibody and neuraminidase inhibition.
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The high incidence of colonization of the cystic fibrosis (CF) airway with Pseudomonas aeruginosa has been attributed to several mechanisms including increased numbers of asialoglycolipid receptors, which may be further increased by exposure to the bacterial exoproduct, neuraminidase. This study examined whether the adherence of P. aeruginosa to fresh CF respiratory epithelial cells can be reduced in vitro by anti-asialoGM1 (anti-aGM1) antibody, neuraminidase inhibition, or the use of asialoGM1 tetrasaccharide as a competitive inhibitor. CF nasal epithelial cells were incubated with a nonmucoid strain of P. aeruginosa, in the presence or absence of a polyclonal anti-aGM1 antibody, the neuraminidase inhibitor 2,3-dehydro-2-deoxy-N-acetyl-neuraminic acid (DANA), or the tetrasaccharide moiety of aGM1. Adherence of bacteria to the apical surface of ciliated epithelial cells was quantified using scanning electron microscopy. Incubation of the cells with bacteria in the presence of either anti-aGM1 antibody or DANA significantly reduced bacterial adherence by 51(7)%, (p<0.01), and 34(9)%, (p<0.01), respectively. In contrast, no significant effect on P. aeruginosa binding was seen in the presence of aGM1 tetrasaccharide. The data are consistent with previous studies on cultured cells, and suggest that the in vivo effects of such interventions should be explored as potential mechanisms to reduce Pseudomonas aeruginosa colonization in cystic fibrosis. (+info)
Multiple intracellular pathways for regulation of chloride secretion in cultured pig tracheal submucosal gland cells.
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Tracheal submucosal glands are of great relative importance in the secretion of chloride and water to the airway lumen. This study aimed to examine whether the cystic fibrosis transmembrane conductance regulator (CFTR) is involved in cyclic adenosine monophosphate (cAMP) or Ca2+-activated Cl- secretion. Regulation of Cl- secretion in cell cultures derived from pig tracheal submucosal gland acini was investigated by X-ray microanalysis. With or without preincubation with CFTR antisense oligodeoxynucleotide (5 microM). A significant decrease in cellular Cl and K concentration was induced by 5 mM 8-bromo-adenosine 3': 5'-cyclic monophosphate (8-bromo-cAMP), 3 microM calcium ionophore ionomycin, 200 microM 5'-uridine triphosphate (UTP) and 200 microM 5'-adenosine triphosphate (ATP), respectively. The decrease in cellular Cl content was significantly inhibited by the Cl- channel blocker 5-nitro-2-(3-phenylpropyl-amino)-benzoic acid (NPPB; 50 microm). Preincubation of the cells with CFTR antisense oligodeoxynucleotide significantly inhibited the 8-bromo-cAMP-induced decrease in Cl, whereas CFTR sense oligodeoxynucleotide had no effect. The effects of ionomycin, ATP or UTP were not blocked by either CFTR antisense oligodeoxynucleotide or CFTR sense oligodeoxynueleotide. To measure the cytosolic free calcium concentration ([Ca2+]i) the cells grown on glass coverslips were loaded with fura-2 tetraoxymethylester (fura-2 AM; 5 microM). The [Ca2+]i was measured as the fluorescence ratio of emission (340/380 nm). Ionomycin (3 microM) caused a rapid increase in [Ca2+]i followed by a sustained plateau, but 8-bromo-cAMP had a more complex effect on [Ca2+]i. Exposure to ATP or UTP caused a rapid increase in [Ca2+]i followed by a decrease. In conclusion, cystic adenosine monophosphate and ionomycin induced Cl- secretion through different intracellular pathways. Adenosine triphosphate and uridine triphosphate also induced Cl- secretion probably with Ca as an intracellular messenger. The cystic fibrosis transmembrane conductance regulator is not involved in Cl- secretion activated by extracellular adenosine triphosphate and uridine triphosphate. (+info)
Energy expenditure and substrate utilization in adults with cystic fibrosis and diabetes mellitus.
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BACKGROUND: The onset of cystic fibrosis-related diabetes mellitus (CFDM) is often associated with a decline in clinical and nutritional status. OBJECTIVE: The purpose of this study was to characterize energy expenditure (EE) and substrate utilization during rest, exercise, and recovery from exercise in patients with CF diagnosed with diabetes mellitus. DESIGN: EE, substrate utilization, minute ventilation, tidal volume, and respiratory rate were calculated by indirect calorimetry durng rest; a 30-min, low-to-medium-intensity exercise bout on a treadmill; and a 45-min postexercise recovery period (in reclining position) in 10 CF, 7 CFDM, and 10 control subjects between 18 and 45 y of age. RESULTS: In all 3 periods, minute ventilation was higher in the CF and CFDM groups than in the control subjects (P < 0.01). During rest and exercise, the CF and CFDM groups maintained EE values at the high end of the normal range of the control subjects. However, during recovery, EE was higher in the CF and CFDM groups than in the control group (P < 0.01). CONCLUSIONS: EE may be higher than usual for the patients with CF and CFDM during periods of recovery from mild exercise or activity because of increased work of breathing consistent with higher ventilatory requirements. This information may be useful for patients receiving nutritional counseling who may choose to exercise regularly, but are concerned about possible weight loss. (+info)
Quality of life in patients with cystic fibrosis and their parents: what is important besides disease severity?
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BACKGROUND: Cystic fibrosis is the most common inherited disease with a fatal outcome in industrialised nations. With the improvement in life expectancy, supporting patients and their families in adapting to life with this chronic progressive disease has become increasingly important. The aim of the present study was to investigate the relationship between health related quality of life (HRQOL) in this population, severity of disease, and cognitive/behavioural factors such as subjective health perception and ways of coping. METHODS: A sample of 89 adolescent and adult patients with cystic fibrosis and 125 parents of younger patients with cystic fibrosis completed questionnaires on health related quality of life and on ways of coping with the illness. Parents were asked to fill out the questionnaires regarding their own quality of life and coping. Multiple regression analyses were performed to examine the relationship between different predictor variables and quality of life. RESULTS: After accounting for the impact of disease severity and hours of treatment per day, the subjective health perception of patients significantly explained variance in their quality of life. Ways of coping were also significantly correlated with HRQOL. In parents the most important factor in explaining variance of HRQOL seems to be the coping style, whereas disease severity of the child and subjective health perception did not show any influence. CONCLUSIONS: The findings support the important role of cognitive and behavioural factors in specific subjective health perception and ways of coping in the adaptation to this severe chronic disease, both in patients themselves and in parents. The results call for a careful assessment of issues of coping and professional support for families of patients with cystic fibrosis in the early course of disease. (+info)