Patterns of Growth and Decline in Lung Function in Persistent Childhood Asthma.

BACKGROUND: Tracking longitudinal measurements of growth and decline in lung function in patients with persistent childhood asthma may reveal links between asthma and subsequent chronic airflow obstruction. METHODS: We classified children with asthma according to four characteristic patterns of lung-function growth and decline on the basis of graphs showing forced expiratory volume in 1 second (FEV1), representing spirometric measurements performed from childhood into adulthood. Risk factors associated with abnormal patterns were also examined. To define normal values, we used FEV1 values from participants in the National Health and Nutrition Examination Survey who did not have asthma. RESULTS: Of the 684 study participants, 170 (25%) had a normal pattern of lung-function growth without early decline, and 514 (75%) had abnormal patterns: 176 (26%) had reduced growth and an early decline, 160 (23%) had reduced growth only, and 178 (26%) had normal growth and an early decline. Lower baseline values for FEV1, smaller bronchodilator response, airway hyperresponsiveness at baseline, and male sex were associated with reduced growth (P<0.001 for all comparisons). At the last spirometric measurement (mean [±SD] age, 26.0±1.8 years), 73 participants (11%) met Global Initiative for Chronic Obstructive Lung Disease spirometric criteria for lung-function impairment that was consistent with chronic obstructive pulmonary disease (COPD); these participants were more likely to have a reduced pattern of growth than a normal pattern (18% vs. 3%, P<0.001). CONCLUSIONS: Childhood impairment of lung function and male sex were the most significant predictors of abnormal longitudinal patterns of lung-function growth and decline. Children with persistent asthma and reduced growth of lung function are at increased risk for fixed airflow obstruction and possibly COPD in early adulthood. (Funded by the Parker B. Francis Foundation and others; ClinicalTrials.gov number, NCT00000575.).

l-citrulline prevents asymmetric dimethylarginine-mediated reductions in nitric oxide and nitrosative stress in primary human airway epithelial cells.

BACKGROUND: Asthma is associated with reduced systemic levels of l-arginine and increased asymmetric dimethylarginine (ADMA). This imbalance leads to nitric oxide synthase (NOS) uncoupling with reduced nitric oxide (NO) formation and greater oxidative and nitrosative stress. Whether this imbalance also occurs in bronchial epitheliumof asthmatics is unknown. OBJECTIVES: We used primary human bronchial epithelial cells (HBECs) from asthmatics and healthy controls to evaluate: (i) ADMA-mediated NOS uncoupling reduces epithelial production of NO and increases oxygen and nitrogen reactive species, and (ii) l-citrulline can reverse this mechanism by recoupling NOS, restoring NO production and reducing oxidative and nitrosative stress. RESULTS: In HBECsIL-13 and INFγ stimulated NOS2 and increased NOx levels. The addition of ADMA reduced NOx and increased H2 O2 levels (p<0.001). Treatment with l-citrulline (800, 1600 µm) rescued NOx when the l-arginine media concentration was 25 µm but failed to do so with higher concentrations (100 µm). Under reduced l-arginine media conditions, HBECs treated with l-citrulline increased the levels of argininosuccinate, an enzyme that metabolizes l-citrulline to l-arginine. l-citrulline prevented the ADMA-mediated increase in nitrotyrosine in HBECs in cells from asthmatics and controls. CONCLUSIONS AND CLINICAL RELEVANCE: Increasing ADMA reduces NO formation and increases oxidative and nitrosative stress in airway epithelial cells. l-citrulline supplementation restores NO formation, while preventing nitrosative stress. These results, suggest that l-citrulline supplementation may indeed be a powerful approach to restore airway NO production and may have a therapeutic potential in diseases in which there is a defective production of NO.

SPLUNC1 as a biomarker of pulmonary exacerbations in children with cystic fibrosis.

BACKGROUND: Short palate, lung, and nasal epithelium clone 1 (SPLUNC1) is an innate defence protein that acts as an anti-microbial agent and regulates airway surface liquid volume through inhibition of the epithelial sodium channel (ENaC). SPLUNC1 levels were found to be reduced in airway secretions of adults with cystic fibrosis (CF). The potential of SPLUNC1 as a biomarker in children with CF is unknown. METHODS: We quantified SPLUNC1, interleukin-8 (IL-8) and neutrophil elastase (NE) in sputum of CF children treated with either intravenous antibiotics or oral antibiotics for a pulmonary exacerbation (PEx)s, and in participants of a prospective cohort of CF children with preserved lung function on spirometry, followed over a period of two years. RESULTS: Sputum SPLUNC1 levels were significantly lower before compared to after intravenous and oral antibiotic therapy for PEx. In the longitudinal cohort, SPLUNC1 levels were found to be decreased at PEx visits compared to both previous and subsequent stable visits. Higher SPLUNC1 levels at stable visits were associated with longer PEx-free time (hazard ratio 0.85, p = 0.04). SPLUNC1 at PEx visits did not correlate with IL-8 or NE levels in sputum or forced expiratory volume in one second (FEV1) but did correlate with the lung clearance index (LCI) (r=-0.53, p < 0.001). CONCLUSION: SPLUNC1 demonstrates promising clinometric properties as a biomarker of PEx in children with CF.

ABO-incompatible lung transplantation in an infant.

Waitlist mortality continues to be a limiting factor for all solid-organ transplant programs. Strategies that could improve this situation should be considered. We report the first ABO-incompatible lung transplantation in an infant. The recipient infant was ABO blood group A1 and the donor group B. The recipient was diagnosed with surfactant protein B deficiency, which is a fatal condition and lung transplantation is the only definitive therapy. At 32 days of age, a bilateral lung transplantation from a donation after cardiac death (DCD) donor was performed. Intraoperative plasma exchange was the only preparatory procedure performed. No further interventions were required as the recipient isohemagglutinins were negative before transplant and have remained negative to date. At 6 months posttransplant, the recipient is at home, thriving, with normal development. This outcome suggests that ABO-incompatible lung transplantation is feasible in infants, providing another option to offer life-saving lung transplantation in this age range.

Contribution of nitric oxide synthases 1, 2, and 3 to airway hyperresponsiveness and inflammation in a murine model of asthma.

Asthma is a chronic disease characterized by increased airway responsiveness and airway inflammation. The functional role of nitric oxide (NO) and the various nitric oxide synthase (NOS) isoforms in human asthma is controversial. To investigate the role of NO in an established model of allergic asthma, mice with targeted deletions of the three known isoforms of NOS (NOS1, 2, and 3) were studied. Although the inducible (NOS2) isoform was significantly upregulated in the lungs of ovalbumin (OVA)-sensitized and -challenged (OVA/OVA) wild-type (WT) mice and was undetectable in similarly treated NOS2-deficient mice, airway responsiveness was not significantly different between these groups. OVA/OVA endothelial (NOS3)-deficient mice were significantly more responsive to methacholine challenge compared with similarly treated NOS1 and NOS1&3-deficient mice. Airway responsiveness in OVA/OVA neuronal (NOS1)-deficient and neuronal/endothelial (NOS1&3) double-deficient mice was significantly less than that observed in similarly treated NOS2 and WT groups. These findings demonstrate an important function for the nNOS isoform in controlling the inducibility of airway hyperresponsiveness in this model of allergic asthma.

Effect of growth hormone therapy on nitric oxide formation in cystic fibrosis patients.

Airway nitric oxide production is decreased in cystic fibrosis. As growth hormone therapy has been shown to increase nitric oxide production in growth hormone-deficient patients, it may also affect nitric oxide production in patients with cystic fibrosis. The objective of the present study was to investigate the effect of growth hormone therapy on systemic and airway nitric oxide formation in patients with cystic fibrosis. Nitric oxide metabolites in serum and urine, amino acid concentrations in serum and sputum, as well as exhaled nitric oxide, were measured in children with cystic fibrosis before, during and after 1 yr of treatment with human growth hormone. Nitric oxide metabolite concentrations increased significantly in serum and urine during the treatment period. Serum amino acid concentrations (including l-arginine, the substrate for nitric oxide synthases) also increased during treatment. The systemic bioavailability of l-arginine for nitric oxide synthases, expressed as ratio of l-arginine/l-ornithine+lysine, remained unchanged. In contrast, l-arginine concentrations in sputum decreased significantly during growth hormone treatment, as did exhaled nitric oxide levels. Treatment with growth hormone in children with cystic fibrosis decreases exhaled nitric oxide by reducing the concentration of l-arginine in the airways.

Interleukin-8 receptor modulates IgE production and B-cell expansion and trafficking in allergen-induced pulmonary inflammation.

We examined the role of the interleukin-8 (IL-8) receptor in a murine model of allergen-induced pulmonary inflammation using mice with a targeted deletion of the murine IL-8 receptor homologue (IL-8r-/-). Wild-type (Wt) and IL-8r-/- mice were systemically immunized to ovalbumin (OVA) and were exposed with either single or multiple challenge of aerosolized phosphate-buffered saline (OVA/PBS) or OVA (OVA/OVA). Analysis of cells recovered from bronchoalveolar lavage (BAL) revealed a diminished recruitment of neutrophils to the airway lumen after single challenge in IL-8r-/- mice compared with Wt mice, whereas multiply challenged IL-8r-/- mice had increased B cells and fewer neutrophils compared with Wt mice. Both Wt and IL-8r-/- OVA/OVA mice recruited similar numbers of eosinophils to the BAL fluid and exhibited comparable degrees of pulmonary inflammation histologically. Both total and OVA-specific IgE levels were greater in multiply challenged IL-8r-/- OVA/OVA mice than in Wt mice. Both the IL-8r-/- OVA/OVA and OVA/PBS mice were significantly less responsive to methacholine than their respective Wt groups, but both Wt and IL-8r mice showed similar degrees of enhancement after multiple allergen challenge. The data demonstrate that the IL-8r modulates IgE production, airway responsiveness, and the composition of the cells (B cells and neutrophils) recruited to the airway lumen in response to antigen.

Effects of fetal exposure to high-fat diet or maternal hyperglycemia on L-arginine and nitric oxide metabolism in lung.

BACKGROUND/OBJECTIVES: Alterations in the L-arginine/nitric oxide (NO) metabolism contribute to diseases such as obesity, metabolic syndrome and airway dysfunction. The impact of early-life exposures on the L-arginine/NO metabolism in lung later in life is not well understood. The objective of this work was to study the effects of intrauterine exposures to maternal hyperglycemia and high-fat diet (HFD) on pulmonary L-arginine/NO metabolism in mice. METHODS: We used two murine models of intrauterine exposures to maternal (a) hyperglycemia and (b) HFD to study the effects of these exposures on the L-arginine/NO metabolism in lung in normal chow-fed offspring. RESULTS: Both intrauterine exposures resulted in NO deficiency in the lung of the offspring at 6 weeks of age. However, each of the exposures leading to different metabolic phenotypes caused a distinct alteration in the L-arginine/NO metabolism. Maternal hyperglycemia leading to impaired glucose tolerance but no obesity in the offspring resulted in increased levels of asymmetric dimethylarginine and impairment of NO synthases. Although maternal HFD led to obesity without impairment in glucose tolerance in the offspring, it resulted in increased expression and activity of arginase in the lung of the normal chow-fed offspring. CONCLUSIONS: These data suggest that maternal hyperglycemia and HFD can cause alterations in the pulmonary L-arginine/NO metabolism in offspring.

Mycobacterium chelonae in a CF patient with anaplastic large cell lymphoma.

A 13-year-old patient with cystic fibrosis was diagnosed with anaplastic large cell lymphoma. At the same time colonization with Mycobacterium chelonae was detected in sputum cultures. Despite massive immunosuppression, the patient did not show evidence of mycobacterial invasive disease. Colonisation persisted for 18 months after discontinuation of chemotherapy and was not detected in the 6 years thereafter. This case highlights the dilemma of differentiating between colonisation and infection if mycobacteria are found in CF sputum samples.

Targeted deletion of the neutral endopeptidase gene alters ventilatory responses to acute hypoxia in mice.

Neutral endopeptidase (NEP) is one of the major endopeptidases responsible for the inactivation of substance P in the carotid body, a neurotransmitter shown to be important in the transduction of hypoxic stimuli. Ventilatory responses to acute hypoxia were measured by indirect plethysmography in unanesthetized, unrestrained wild-type mice and in mice in which the NEP gene was deleted (NEP -/-). Ventilation was measured while the animals breathed room air: 12% O(2) in N(2) and 8% O(2) in N(2). Deletion of the NEP gene caused marked alterations in both the magnitude and composition of the hypoxic ventilatory response to both 8% O(2) in N(2) and 12% O(2) in N(2), compared with the wild-type mice (C57BL/6J) on the same genetic background as the NEP -/- mice. Treatment of C57BL/6J mice with thiorphan, a NEP inhibitor, resulted in a greater ventilatory response to 8% O(2) because of a significantly greater shortening of expiratory time. The results of these studies demonstrate that NEP plays an important role in modifying the expression of the ventilatory response to acute hypoxia.

Cystic fibrosis lung disease: the role of nitric oxide.

This review summarizes current knowledge about the role of nitric oxide (NO) in cystic fibrosis (CF) lung disease. NO is endogenously produced by a group of enzymes, the NO synthases (NOSs). There are three isoforms of NOS, each encoded by different genes: neuronal (nNOS), immune or inducible (iNOS), and endothelial (eNOS) nitric oxide synthase.(1) They all form NO and L-citrulline by enzymatic oxidation of L-arginine. This reaction requires a number of cosubstrates, including molecular oxygen and tetrahydrobiopterin. It is now known whether all three isoenzymes are constitutively expressed in cells of the respiratory tract and that their gene expression is inducible.(2,3) NO production by iNOS, the "high-output" NOS, is stimulated by bacterial lipopolysaccharide (LPS) as well as proinflammatory cytokines such as interleukin (IL)-1gamma, IL-2, interferon (IFN)-gamma, and tumor necrosis factor (TNF). In contrast to nNOS and eNOS, activation of iNOS does not require an increase in intracellular Ca(2+) concentration.

Decreased concentration of exhaled nitric oxide (NO) in patients with cystic fibrosis.

Nitric oxide (NO) is produced by various cell types in the human respiratory tract. Endogenously produced nitric oxide is detectable in the exhaled air of healthy individuals. Exhaled NO has been shown to be increased in airway inflammation, most probably due to cytokine-mediated activation of NO synthases. To assess whether NO can serve as a marker of inflammation in cystic fibrosis (CF) lung disease, we measured exhaled NO in CF patients with a chemiluminescence analyser. Single breath measurements were performed in 27 stable CF patients (age range, 6-40 years) and 30 non-smoking controls (age range, 6-37 years). Exhaled NO concentrations were 9.1 +/- 3.6 ppb in the controls and 5.9 +/- 2.6 ppb (P < 0.001) in CF patients. To account for room air NO concentrations on the measurement of exhaled NO, we also calculated the difference between exhaled NO and ambient NO concentrations. Difference values were also significantly lower in CF compared with controls (P < 0.0001). In CF patients there was a positive correlation between exhaled NO and forced vital capacity (r = 0.43, P = 0.033), suggesting that exhaled NO is lower in patients with severe lung disease than in those with mild disease. We conclude that measurements of exhaled NO in CF does not reflect activity of CF airway inflammation. The decreased concentrations of exhaled NO may be due to inhibitory effects of inflammatory cytokines on NO syntheses in the airways and alveolar epithelial cells or to increased retention in airway secretions.

Isovolume pressure/flow curves of rapid thoracoabdominal compressions in infants without respiratory disease.

To assess whether flow limitation can be achieved during rapid thoracoabdominal compressions (RTC), we performed esophageal pressure measurements in 11 healthy infants less than 3 months of age. Recordings of esophageal pressure were obtained with an esophageal balloon placed in the lower esophagus. RTCs were started at 20 cm H2O and increased to 140 cm H2O or until the infant responded with glottic closure to the compression. Flow limitation was assessed from isovolume pressure flow curves at peak flow and flow at FRC (V'max, FRC). The transmission of jacket pressure was higher at peak flow than at FRC for pressures below 60 cm H2O, due to active inspiration during the compression. Active inspiration was not observed at compression pressures above 80 cm H2O, as reflected by a plateau in the esophageal pressure tracing. Esophageal pressure increased parallel to the compression pressure at jacket pressures below 60 cm H2O. The relationship between jacket pressure and esophageal pressure became curvilinear at high compression pressures and plateaued at compressions above 100 cm H2O, so that further increases in jacket pressure did not increase esophageal pressure. Flow limitation was seen in all infants studied, as indicated by a lack of increase in flow with increasing esophageal pressures for V'max, FRC. Jacket compression pressures of 60 cm H2O and esophageal pressures of 20 cm H2O were sufficient to reach maximal expiratory flow. These data indicate that jacket pressure is a poor indicator of pleural pressure at high compression pressures in young healthy infants, and high pressures are not needed, as flow limitation is seen during RTCs at moderate compression pressures.

Effect of inhaled nitric oxide on pulmonary function in cystic fibrosis.

Concentrations of nitric oxide (NO) have been found to be reduced in both the upper and lower airway of patients with cystic fibrosis (CF). As NO modulates bronchomuscular tone, low NO levels may contribute to the obstructive lung disease in these patients. To assess whether increasing inspiratory NO concentrations has any impact on lung function, we have studied 13 CF patients aged 14-38 years in a clinically stable condition and nine healthy controls. NO was applied via a mixing chamber for 5 min with NO concentrations of 100 parts per billion, 1 and 40 parts per million. Spirometry was performed at baseline and after inhalation on each occasion. There were no clinical side-effects at any NO concentration and no changes in oxygen saturation were observed. Lung function remained unchanged in all subjects throughout the study period. Sputum nitrate and nitrite concentrations before and after inhalation of high NO concentrations (40 ppm) in eight CF patients did not show any significant changes, even though a tendency to higher nitrate levels was observed (399 +/- 231 vs. 556 +/- 474 mumol l-1). Therefore, inhaled NO at either the physiological levels present in the upper airway of normal individuals or those used therapeutically to treat pulmonary hypertension has no immediate effect on bronchomuscular tone in patients with cystic fibrosis.

Serum insulin-like growth factors IGF-I and IGFBP-3 in children with slipped capital femoral epiphysis.

Hormonal imbalance in puberty and biomechanical overload due to obesity have been implied in the still unknown cause of slipped capital femoral epiphysis (SCFE). Local mediators of growth hormone (GH) action, such as insulin-like growth factor I (IGF-I), play a crucial role in the development of the growth plate cartilage. Concentrations of IGF-I and its binding protein 3 (IGFBP-3) were measured in the serum of 19 SCFE children without endocrine disorders. Standing height and body weight were determined. The results were related to the bone age. Concentrations for IGF-I and IGFBP-3 were predominantly within the normal ranges for chronologic age and bone age. The correlation of IGF-I and IGFBP-3 serum levels was high. Standing height and body weight showed a tendency toward the higher percentile ranges. Ten of 19 patients were above the 97th percentile concerning their weight for height. Bone age did not differ significantly from chronologic age. Serum concentrations of IGF-I and IGFBP-3 provided no evidence of a disturbance of the somatotropic axis in SCFE children. Increased body weight associated with normal skeletal maturation implies a mechanical stress factor in the cause of SCFE in these children.

A randomized controlled trial of inhaled L-arginine in patients with cystic fibrosis.

BACKGROUND: Cystic fibrosis (CF) airways are nitric oxide (NO) deficient. We studied safety and efficacy of repeated inhalations of nebulized L-arginine, the substrate for NO synthase (NOS), in patients with CF. METHODS: Double-blind, randomized, placebo-controlled crossover treatment trial of twice daily inhalation of 500 mg L-arginine for two weeks compared to inhalation of saline in 19 CF patients (ClinicalTrials.gov Identifier: NCT00405665). RESULTS: L-arginine inhalation was well tolerated and resulted in a significant increase in exhaled NO. FEV1 increased by an average of 56 ml compared to -8 ml after saline solution; but this difference did not reach statistical significance. Sputum concentrations of L-ornithine, the product of arginase activity, increased significantly while the L-ornithine derived polyamines did not. There was no change in inflammatory markers in sputum. CONCLUSION: Repeated inhalation of L-arginine in CF patients was safe and well tolerated. Inhaled L-arginine increased NO production without evidence for changes in airway inflammation.

Pediatric lung transplantation.

Lung transplantation is an accepted therapy for selected pediatric patients with severe end-stage vascular or parenchymal lung disease. Collaboration between the patients' primary care physicians, the lung transplant team, patients, and patients' families is essential. The challenges of this treatment include the limited availability of suitable donor organs, the toxicity of immunosuppressive medications needed to prevent rejection, the prevention and treatment of obliterative bronchiolitis, and maximizing growth, development, and quality of life of the recipients. This article describes the current status of pediatric lung transplantation, indications for listing, evaluation of recipient and donor, updates on the operative procedure,graft dysfunction, and the risk factors, outcomes, and future directions.

Pharmacokinetics of inhaled colistin in patients with cystic fibrosis.

OBJECTIVES: Inhaled colistin is commonly used in patients with cystic fibrosis (CF), but only limited data are available to define its pharmacokinetic profile. PATIENTS AND METHODS: We performed a multicentre study in 30 CF patients to assess sputum, serum and urine concentrations after a single dose of 2 million units of colistin administered by inhalation. In a subgroup of patients we also compared the efficacy of two different nebulizers for administration of inhaled colistin. RESULTS: Serum concentrations of colistin reached their maximum 1.5 h after inhalation and decreased thereafter. Serum concentrations were well below those previously reported for systemic application in all patients. A mean 4.3+/-1.3% of the inhaled dose was detected in urine. Elimination characteristics did not differ significantly from those previously reported for systemic application. A positive correlation was found between forced expiratory volume in 1 s (FEV1) in per cent predicted and both AUC and maximal colistin concentrations in serum (Cmax). Maximum sputum concentrations were at least 10 times higher than the MIC breakpoint for Pseudomonas aeruginosa proposed by the British Society for Antimicrobial Chemotherapy. Although sputum drug concentrations decreased after a peak at 1 h, the mean colistin concentrations were still above 4 mg/L after 12 h. No differences were seen in polymyxin E sputum concentrations, for CF patients between the two nebulizer systems. CONCLUSIONS: The low systemic and high local concentrations of colistin support the use of inhaled colistin in CF patients infected with P. aeruginosa.

[Cystic fibrosis modifying genes]. / Modifizierende Gene bei der zystischen Fibrose.

Cystic fibrosis is a common autosomal recessive disease that is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. The CFTR gene encodes a membrane-bound chloride ion channel. CFTR gene mutations cause alterations in fluid and salt secretion of various tissues. The CF phenotype is highly variable even in siblings and twins carrying the same CFTR mutations. The course of CF pulmonary disease is modulated by both environmental and genetic factors independent of CFTR. This review summarises association studies that focused on disease modifier genes in CF. Understanding the molecular and cellular basis of the genotype-phenotype associations will help to better understand the disease and to identify new targets for therapeutic interventions in CF.