Bronchoalveolar lavage in children. ERS Task Force on bronchoalveolar lavage in children. European Respiratory Society

Neurotrophin overexpression in lower airways of infants with respiratory syncytial virus infection

RATIONALE

Nerve growth factor and its receptors are upregulated in the lungs of weanling rats with lower respiratory tract infection caused by the respiratory syncytial virus (RSV), and this is a major mechanism of the inflammatory response against the virus. However, no information is available in humans.

OBJECTIVES

We sought to determine whether the expression of neurotrophic factors and receptors is increased in human infants infected with RSV.

METHODS

We used a highly sensitive immunoassay to measure the concentrations of nerve growth factor and brain-derived neurotrophic factor proteins in serum samples and in the supernatants and cell fractions of nonbronchoscopic bronchoalveolar lavage fluid. We also used immunofluorescence to detect expression in airway cells of the tyrosine kinase receptor TrkA, which binds nerve growth factor with high affinity. Samples were obtained at 24 and 48 hours postintubation from 31 mechanically ventilated infants: 15 patients with RSV infection, 5 patients with respiratory infection negative for RSV, and 11 postsurgical patients without respiratory infection.

MAIN RESULTS

Data show significantly higher concentrations of both neurotrophins in the cell fractions of bronchoalveolar lavage samples obtained from infants with RSV infection compared with control infants, whereas no significant difference was found in supernatants or serum samples. We also detected tyrosine kinase receptor immunoreactivity only in cells from airways infected with RSV.

CONCLUSIONS

We conclude that neurotrophic factors and receptors are overexpressed in human airways infected by RSV, and may contribute to airway inflammation and hyperreactivity.

Detection of human metapneumovirus RNA sequences in nasopharyngeal aspirates of young French children with acute bronchiolitis by real-time reverse transcriptase PCR and phylogenetic analysis

Human metapneumovirus (HMPV) was the unique viral pathogen detected by a real-time reverse transcriptase PCR (RT-PCR) assay in 6 (6.4%) of 94 consecutive French children hospitalized for acute bronchiolitis from September 2001 to June 2002. This virus was identified as the third etiological cause of bronchiolitis, after respiratory syncytial virus and rhinovirus (35 [37%] and 21 [22%] of 94 cases, respectively). Phylogenetic analysis of F-gene sequences demonstrated the cocirculation of distinct HMPV genotypes during this study. These findings highlight the need to implement a rapid HMPV RT-PCR detection assay for the clinical diagnosis of respiratory infections in pediatric patients with bronchiolitis.

Reduction of Oxidative Stress Marker in Lung Fluid of Preterm Infants after Administration of Intra-Tracheal Liposomal Glutathione

BACKGROUND

Low levels of glutathione are associated with subsequent chronic lung disease in preterm infants. Incorporation of glutathione into liposomes offers a method of increasing levels with a prolonged half-life compared with direct inhalation.

OBJECTIVES

The aim of this study was to examine the clinical feasibility of administering a single dose of liposomal glutathione and its effectiveness at raising glutathione at 12 and 24 h after treatment.

METHODS

Fourteen ventilated preterm infants from the Regional Neonatal Intensive Care Unit at Liverpool Women's Hospital received 1 mg/kg or 10 mg/kg liposomal glutathione intra-tracheally and bronchoalveolar lavage fluid was collected prior to treatment, 12 and 24 h after dosing for glutathione and malondialdehyde estimation.

RESULTS

Mean glutathione was initially 12.2 micromol/l, increasing to 52.8 micromol/l at 12 h (p = 0.006). Mean malondialdehyde was initially 265.6 nmol/l decreasing to 11.2 nmol/l at 12 h (p = 0.018).

CONCLUSIONS

Intra-tracheal liposomal glutathione instillation offers a feasible method of raising pulmonary glutathione in preterm infants and shows biochemical antioxidant effects.

Connatal tuberculosis in a very premature infant

Connatal tuberculosis is increasing in incidence and the mortality and morbidity of this disease remains high. We report a 27-week-old, 896 g female premature infant who had mild respiratory distress syndrome after birth. She developed signs of infection, progressive pneumonia and atelectasis which did not respond to mechanical ventilation and antibiotics. At 41 days of age, Mycobacterium tuberculosis was isolated from the non-bronchoscopic bronchoalveolar lavage. The isolate was sensitive to isoniazid, rifampin, streptomycin, and pyrazinamide. Miliary tuberculosis was subsequently diagnosed in her mother on a chest X-ray film and sputum cultures. The infant was treated successfully with anti-tuberculosis drugs. She had normal growth and development at the chronological age of 20 months old.

CONCLUSION

Connatal tuberculosis should be considered in premature infants with symptoms of sepsis refractory to antibiotics. Most premature infants with connatal tuberculosis have lung involvement, and non-bronchoscopic bronchoalveolar lavage can be a useful procedure to establish the diagnosis.

Relationship between antenatal inflammation and antenatal infection identified by detection of microbial genes by polymerase chain reaction

Although antenatal infection is thought to play an important role in the pathogenesis of preterm labor and neonatal diseases, the exact mechanisms are largely unknown. We sought to clarify the relationship between antenatal infection and intrauterine and neonatal inflammation. Samples were obtained from 41 preterm infants of <33 wk gestation delivered to 36 mothers and analyzed for the presence of 16s ribosomal RNA (16s rRNA) genes using PCR and for the proinflammatory cytokines IL-6 and IL-8. In 16 (44%) mother-baby pairings, at least one sample was found to be positive for the presence of 16s rRNA genes. All but one of the positive samples were from mothers presenting with preterm prelabor rupture of membranes (pPROM) or in spontaneous idiopathic preterm labor. A strong association was found between the presence of 16s rRNA genes and chorioamnionitis and with funisitis. A marked increase in IL-6 and IL-8 was noted in all tissues positive for 16s rRNA genes, including placenta, fetal membranes, cord blood serum, and, where samples were available, in bronchoalveolar lavage fluid (BAL) and in amniotic fluid. Interestingly, gastric fluid was always positive for 16s rRNA genes if any other intrauterine or BAL sample was positive, suggesting that this sample may provide an alternative to amniotic fluid to identify antenatal infection. In conclusion, we have found that microbial genes are particularly prevalent in pPROM and spontaneous preterm labor groups and that their presence is strongly associated with a marked intrauterine inflammatory response.

BALF nitrite as an indicator of inflammation in children with cystic fibrosis

BACKGROUND

A unique substance reflecting the degree of inflammation localized to the lower respiratory tract in patients with cystic fibrosis (CF) has been the concern of several investigators and nitric oxide has gained interest for this purpose in the last decades.

OBJECTIVES

The aim of this study was to evaluate the cytokine and nitrite levels by showing the relationship between them in serum and bronchoalveolar lavage fluid (BALF) of patients with CF and patients in which flexible fiberoptic bronchoscopy (FFB) was applied because of indications other than infection.

METHODS

20 children with CF with mean age 8.2 years and 10 children as control group with mean age 4.2 years were included in the study. Cultures for aerobes, anaerobes, fungi and mycobacteria, cell differentials, cytokine and nitrite measurements were made from BALF specimens. White blood cell (WBC) count, erythrocyte sedimentation rate (ESR), quantitative C-reactive protein (QCRP), cytokine and nitrite levels were measured from serum samples.

RESULTS

BALF neutrophil, TNF-alpha, IL-8 and nitrite levels were significantly higher in patients with CF than control patients. There was no correlation between serum and BALF cytokine and nitrite levels. However, there was a significantly positive correlation between BALF IL-8 and nitrite levels in patients with CF (r = 0.5) and also in control patients (r = 0.6).

CONCLUSIONS

The results suggest that BALF nitrite levels reflect the degree of inflammation localized to lower respiratory tract and may be a useful indicator of airway inflammation for patients with CF.

[Utility of bronchoalveolar lavage in immunocompromised children: diagnostic yield and complications]

OBJECTIVE

Immunocompromised children are at high risk for developing pneumonia due to opportunistic pathogens. The role of bronchoalveolar lavage (BAL) in the evaluation of such patients is still controversial.

MATERIAL AND METHOD

We reviewed the hospital records of immunosuppressed patients with respiratory symptoms who had undergone BAL in the pediatric department of the Hospital Clinico de la Pontificia Universidad Católica of Chile.

RESULTS

Sixty-eight BAL were performed on 54 children (mean age: 7.5 years) receiving wide-spectrum antibiotic treatment. The most frequent respiratory signs and symptoms were fever (90%) and cough and respiratory distress (81%); 18% had neutropenia and 43% thrombocytopenia. A specific pathogen was identified in BAL samples for 25 patients (37%). The pathogens isolated were bacteria in 21 cases, viruses in 6, Pneumocystis carinii in 5, fungi in 4, and Mycobacterium tuberculosis in one. Fourteen (19%) of the children who underwent BAL were on mechanical ventilation. Outcome was satisfactory in all cases. Twenty-one complications were recorded, 17 of which were minor (mild hypoxemia or fever) and 4 major, requiring tracheal intubation. No deaths were recorded.

CONCLUSIONS

Evaluation by fiberoptic bronchoscopy together with BAL proved to be a safe procedure with an adequate diagnostic yield that made it possible to determine the etiology of the pulmonary infiltrates seen in chest x-rays. Both positive and negative results of BAL were useful for treating the patients.

Blood transfusion and pulmonary lipid peroxidation in ventilated premature babies

Urinary malondialdehyde (MDA; a biochemical marker of lipid peroxidation) is increased following the receipt of blood transfusions in premature babies. This indicates an increased level of oxidative damage somewhere in the body. The aim of this study was to determine whether the lung may be a site of increased oxidative damage following blood transfusions. This was achieved by examining the relationship between blood transfusion and levels of MDA in bronchoalveolar lavage (BAL) fluid from ventilated premature babies. The study was a retrospective analysis of data obtained from a group of 42 ventilated premature babies of less than 32 weeks' gestation. Twenty-seven babies received blood transfusions, and 9 received at least one transfusion during the first week of life when daily BAL samples were being taken. Pulmonary epithelial lining fluid (ELF) was sampled by BAL daily during the first week of life and weekly thereafter. MDA was measured by an established high performance liquid chromatography (HPLC) technique. There was a significant positive correlation between volume of blood transfusions received and peak and mean ELF MDA levels (r=0.810, peak; r=0.740, mean; n=21). During the first week of life, when daily samples were being taken, the mean ELF MDA level after blood transfusion (1.829 microM; SE, 0.529) was significantly greater than before transfusion (0.928 microM; SE, 0.297) (n=9). In babies who received 2 transfusions within the first week (n=5), the MDA level was elevated further following the second transfusion (2.825 microM; SE, 0.346). The results of this study indicate that pulmonary oxidative damage increases after the receipt of blood transfusions. Babies receiving blood transfusions show a greater incidence of pulmonary oxidative stress and poor clinical outcome. This may simply reflect that the sickest babies are those most in need of blood transfusion, and that there is no causal relationship. However, the possibility of a causal relationship between blood transfusions and oxidative damage exists and should be investigated.

HFOV in premature neonates: effects on pulmonary mechanics and epithelial lining fluid cytokines. A randomized controlled trial

OBJECTIVE

Ventilation strategies for preterm neonates may influence the severity of pulmonary dysfunction and later development of chronic lung disease. The objective of this report is to compare the effects of high-frequency oscillatory ventilation (HFOV) versus synchronized intermittent mandatory ventilation (sIMV) from the points of views of biochemical and functional variables.

DESIGN

Randomized controlled trial.

SETTING

Third level NICU.

PATIENTS AND PARTICIPANTS

Forty preterm neonates with a gestational age of 24-29 weeks were randomly assigned to one of the two above-mentioned ventilation strategies within 30 min from birth.

MEASUREMENTS AND RESULTS

At 1, 3, 5, and 7 days, the babies were monitored by means of ventilator indices, pulmonary function, and eight pro-inflammatory or anti-inflammatory cytokines measured in bronchoalveolar lavage fluid. The neonates assigned to the HFOV procedure benefited from early and sustained improvement in pulmonary mechanics and gas exchange-significantly higher dynamic respiratory compliance values, significantly lower expiratory airway resistance and oxygenation index values-with earlier extubation as compared to the neonates assigned to sIMV treatment, and showed significantly lower transforming growth factor-beta1 concentrations in bronchoalveolar lavage fluid.

CONCLUSIONS

The results of this randomized clinical trial support the hypothesis that early and exclusive use of HFOV, combined with optimum volume strategy, has a beneficial effect during the acute phase of lung injury.

Dual infection of infants by human metapneumovirus and human respiratory syncytial virus is strongly associated with severe bronchiolitis

The association between severe bronchiolitis and dual infection by human metapneumovirus (hMPV) and human respiratory syncytial virus (hRSV) was investigated in !2-year-old infants with bronchiolitis who were admitted to the hospital during the 2001–2002 winter season. hMPV in nasopharyngeal aspirate and/or cells and fluid collected by nonbronchoscopic bronchoalveolar lavage was detected by reverse transcriptase-polymerase chain reaction (RT-PCR). hRSV was detected in nasopharyngeal aspirate and/or cells and fluid collected by nonbronchoscopic bronchoalveolar lavage by enzyme immunoassay, tissue culture, and RT-PCR. Dual infection with hMPV and hRSV confers a 10-fold increase in relative risk (RR) of admission to a pediatric intensive-care unit for mechanical ventilation (RR, 10.99 [95% confidence interval, 5.0–24.12]; P < .001, by Fisher exact test). Dual infection by hMPV and hRSV is associated with severe bronchiolitis.

Interleukin (IL)-1 beta in tracheal aspirates from premature infants induces airway epithelial cell IL-8 expression via an NF-kappa B dependent pathway

Tracheal aspirate IL-8 concentration and airway epithelial cell IL-8 expression are each increased in premature infants undergoing mechanical ventilation. We sought to determine the cytokines responsible for IL-8 expression in this context. Tracheal aspirates were collected from 18 mechanically ventilated premature infants. IL-8 protein abundance was high in tracheal aspirates from ventilated premature infants (mean, 5806 +/- 4923 pg/mL). IL-1 alpha (mean, 20 +/- 6 pg/mL), IL-1 beta (mean 67 +/- 46 pg/mL), and tumor necrosis factor (TNF)-alpha (mean, 8 +/- 2 pg/mL) were also found. Incubation of tracheal aspirates with 16HBE14o- human bronchial epithelial cells increased IL-8 protein in both cell lysates and supernatants, as well as transcription from the IL-8 promoter. Aspirates also induced nuclear factor (NF)-kappa B activation. Mutation of the IL-8 promoter NF-kappa B site abolished aspirate-induced IL-8 transcription. Endotoxin concentrations in the tracheal aspirates were negligible and incapable of inducing IL-8 promoter activity. Finally, incubation of tracheal aspirates with a neutralizing antibody against IL-1 beta reduced epithelial cell IL-8 production, whereas neutralizing antibodies against IL-1 alpha and TNF-alpha had no effect. We conclude that airway fluid from mechanically ventilated premature infants contains soluble factors capable of inducing airway epithelial cell IL-8 expression via a NF-kappa B-dependent pathway, and that IL-1 beta plays a specific role in this process.

Pediatric interstitial lung disease revisited

The spectrum of pediatric interstitial lung disease (PILD) includes a diverse group of rare disorders characterized by diffuse infiltrates and disordered gas exchange. Children with these conditions typically present with tachypnea, crackles, and hypoxemia. Recent advances have been made in the identification of different types of PILD that are unique to infancy. More exciting has been the discovery of genetic abnormalities of surfactant function, now described in both children and adults. A systematic evaluation of the child presenting with diffuse infiltrates of unknown etiology is essential to the diagnosis. Most often, lung biopsy is required. Current treatment options remain less than satisfactory, and morbidity and mortality remain considerable.

Microaspiration in Infants with Laryngomalacia

OBJECTIVES/HYPOTHESIS

Laryngomalacia is the most common congenital laryngeal anomaly and the most frequent cause of stridor in infants. Infants with laryngomalacia may have associated respiratory symptoms other than stridor. In this study, we evaluated whether infants with laryngomalacia have episodes of microaspiration by calculating the amount of lipids present in the alveolar macrophages.

STUDY DESIGN

We reviewed bronchoalveolar lavage (BAL) findings obtained in 14 infants with laryngomalacia and in 11 control children.

METHODS

BAL was performed during flexible fiberoptic bronchoscopy (FFB) to diagnose persistent stridor. The presence of microaspiration was determined by evaluating the amount of lipid per single macrophage, assigning each cell a score from 0 to 4 according to the amount of lipid in the cytoplasm.

RESULTS

The lipid-laden macrophage index was similar in patients and controls (31.5, range 12-177 vs. 45, range 35-106). In 5 of the 14 (36%) patients the index exceeded 100, and more than 25% of the cells were graded 3 and 4, indicating the presence of microaspiration. The lipid-laden macrophage index correlated significantly with the number and percentage of BAL neutrophils (Pearson correlation test, r = 0.83, P < .001 and r = 0.925, P < .001) as a marker of lung inflammation.

CONCLUSIONS

Infants with laryngomalacia may have episodes of microaspiration. BAL performed during FFB to evaluate stridor may add helpful therapeutic information without increasing the risks of the procedure.

The role of matrix metalloproteinases -9 and -2 in development of neonatal chronic lung disease

AIM

Matrix metalloproteinases (MMPs) -9 and -2 degrade type-IV collagen, a major constituent of lung basement membrane, and may have a role in the pathogenesis of neonatal chronic lung disease (CLD). We determined factors influencing MMP levels in neonatal bronchoalveolar lavage (BAL) fluid to establish whether an imbalance between MMP and its inhibitor could be implicated in CLD.

METHODS

We measured MMP-9 and -2 and tissue inhibitor of metalloproteinase-1 (TIMP-1) levels in 316 BAL fluid samples from 121 babies of gestational ages 23 to 42 wk over the first 14 d of life to determine effects of gestation and postnatal age. Median MMP-9, -2, TIMP-1 and MMP-9/TIMP-1 ratio in BAL were further studied in a subgroup of 85 babies <33 wk gestation to determine their ability to predict CLD and to establish effects of antenatal corticosteroid therapy (ANCS).

RESULTS

MMP-9, -2 and TIMP levels did not vary with postnatal age over the first week. Median MMP-9 levels and MMP-9/TIMP-1 ratio increased with decreasing gestation in preterm babies. The MMP-9/TIMP-1 ratio was higher in babies who developed CLD, implying a proteinase/antiproteinase imbalance, but this association disappeared when controlled for gestational age. ANCS had no effect on BAL fluid MMP or TIMP levels.

CONCLUSION

MMPs may have a role in the development of lung injury and fibrosis, but estimating their levels in the first week of life does not help with prediction of CLD.

Mitogenic activity of tracheal effluents from premature infants with chronic lung disease

Lung injury alters the expression and release of growth factors that disrupt postnatal pulmonary development in newborns and causes chronic lung disease (CLD). The effect of these factors, released into the airways of newborns with CLD, on cell proliferation and collagen production was characterized in vitro. Human fetal lung fibroblast and alveolar-epithelial-like cell lines (FHs 738Lu and A549, respectively) were exposed to tracheal effluents from infants with CLD (mean gestation, 24.7 +/- 0.9 wk; birth weight, 666 +/- 85 g; postnatal age, 0-62 d). In both cell types, proliferation was assessed by measuring [(3)H]-thymidine uptake; in fibroblasts, collagen production was analyzed by measuring [(3)H]-proline incorporation. The activity of specific growth factors in effluents was determined using anti-growth factor antibodies and the growth factors themselves. Growth factors in tracheal effluents promoted proliferation in a dose-dependent manner and caused up to a 10.2- and 3.1-fold increase in thymidine uptake by fibroblasts and epithelial cells, respectively. Collagen production by fibroblasts increased dose dependently, peaking at 177% of baseline. Antibody against transforming growth factor beta-1 (TGF-beta(1)) inhibited proliferation and the increase in collagen production by 31% (p = 0.01) and 14% (p = 0.045), respectively. Antibody against hepatocyte growth factor (HGF) inhibited proliferation of epithelial cells (25%, p = 0.039). The effects of exogenous TGF-beta(1) on fibroblasts and HGF on epithelial cells resembled those of tracheal effluents. Potent mitogenic and differentiating substances are released into the tracheal effluents of newborns with CLD. TGF-beta(1) may worsen CLD by inducing fibrosis whereas HGF may favor resolution by promoting epithelialization.

Chorioamnionitis increases matrix metalloproteinase-8 concentrations in bronchoalveolar lavage fluid from preterm babies

OBJECTIVE

To determine the effects of chorioamnionitis and antenatal corticosteroids on matrix metalloproteinase-8 (MMP-8) concentrations in bronchoalveolar lavage (BAL) fluid from preterm babies in the first week of life.

DESIGN

Prospective observational study.

SETTING

Regional neonatal intensive care unit.

PATIENTS

Thirty five ventilated preterm babies < 33 weeks gestation, seven of whom were born after chorioamnionitis, which was diagnosed histologically as the presence of inflammatory cells in the chorioamnionic plate.

METHODS

MMP-8 was measured by enzyme linked immunosorbent assay (ELISA) in 90 serial BAL samples taken during the first six postnatal days. The median MMP-8 concentration for each baby was calculated.

RESULTS

Median MMP-8 concentrations were higher in the chorioamnionitis group than in those without (43 v 5 ng/ml). Partial or complete courses of antenatal corticosteroids had no effect on MMP-8 concentrations.

CONCLUSIONS

Higher concentrations of MMP-8 are found in BAL fluid from preterm babies from pregnancies complicated by chorioamnionitis. This type I collagenase may contribute to the lung injury that occurs in some babies with respiratory distress syndrome.

The role of neutrophil apoptosis in the resolution of acute lung injury in newborn infants

BACKGROUND

The persistent airway neutrophilia observed in chronic lung disease of prematurity (CLD) may reflect inappropriate suppression of neutrophil apoptosis.

METHODS

134 bronchoalveolar lavage (BAL) samples were obtained from 32 infants requiring mechanical ventilation for respiratory distress syndrome (RDS): 13 infants (median gestation 26 weeks, range 23 to 28) subsequently developed CLD (CLD group), and 19 infants (gestation 31 weeks, range 25 to 39) recovered fully (RDS group). A further 73 BAL samples were obtained from 20 infants (median age 2 days, range 1 to 402) receiving extracorporeal membrane oxygenation (ECMO) for severe respiratory failure.

RESULTS

Neutrophil apoptosis was increased in the RDS group (mean (SEM) neutrophil apoptosis on day 7 BAL: RDS 17.0 (8.6)% v CLD 0.7 (0.2)% (p<0.05)). BAL fluid obtained from RDS but not CLD patients was proapoptotic to neutrophils (apoptosis ratio BAL fluid/saline control: day 1, RDS 9.8 (5.5) v CLD 1.2 (0.1) (p<0.05); day 2, RDS 4.32 (2.8) v CLD 0.5 (0.4) (p<0.05)). There were similar findings in the ECMO group: survivors had proapoptotic BAL fluid compared with non-survivors (apoptosis ratio day 1, survivors 7.9 (2.1) v non-survivors 2.1 (0.7) (p<0.05)).

CONCLUSIONS

Inappropriate suppression of neutrophil apoptosis may be associated with a poor outcome in newborn infants with respiratory failure.

Bronchoalveolar lavage cellularity in infants with severe respiratory syncytial virus bronchiolitis

AIM

To examine over time, the cellular response within the lungs of infants ventilated with respiratory syncytial virus (RSV) bronchiolitis and to compare this response in infants born at term with those born preterm.

METHODS

Non-bronchoscopic bronchoalveolar lavage (BAL) samples were taken from 47 infants (24 born at term and 23 born preterm) who were ventilated for RSV positive bronchiolitis and 10 control infants. BAL cellularity and differential cell counts were calculated using standard techniques.

RESULTS

Total cellularity in BAL over the first four days of ventilation in infants with RSV bronchiolitis was greater in term infants (median 2.2 (IQR 4.27) x 10(6) cells/ml) compared with preterm infants (0.58 (1.28) x 10(6) cells/ml). The magnitude of the cellular response in preterm infants with bronchiolitis was similar to that in the control group measured on day 1 (0.62 (0.77) x 10(6) cells/ml). BAL cellularity decreased progressively from the time of intubation in term infants, but remained relatively constant in preterm infants up to seven days after intubation.

CONCLUSIONS

There are differences in the magnitude and type of pulmonary cellular response in term and preterm infants ventilated with RSV bronchiolitis. The cellular response in term infants with bronchiolitis differs from that in a control group of infants. These differences may reflect variations in cellular recruitment in the lung and/or variations in airway calibre.

Duration of effect of intravenous antibiotics on spirometry and sputum cytokines in children with cystic fibrosis

Intravenous (IV) antibiotics are a mainstay of therapy in children with cystic fibrosis. It is unclear, however, over what period associated improvements in pulmonary function are maintained, and to what extent the underlying inflammatory process is impeded in children admitted for a course of IV antibiotics. This was a prospective, interventional study of 14 children (median age, 14 years; interquartile range, 10-14) with cystic fibrosis who were regular sputum producers and who required admission for a 2-week course of IV antibiotics. Children performed spirometry and provided a sputum sample prior to starting IV antibiotics and then weekly for 6 weeks, the first 2 weeks of which IV antibiotics were given. Sputum IL-8, TNF-alpha, IL-6, IL-10, MIP1-alpha, and elastase were measured. Seven children were asked to repeat the protocol in a subsequent exacerbation to assess similarities in response to therapy. Significant improvements were seen in forced expired volume in 1 sec (FEV(1)) in association with IV antibiotics (27% relative improvement in predicted from baseline to end of week 1, median FEV(1) 41.3% increasing to 52.2%), but this continued only 1 week following cessation of antibiotics. Although IL-8 demonstrated a trend for reduction in association with antibiotics, no significant profile was demonstrated for any of the cytokines assessed. IL-10 was detectable in 64% of samples (all <100 pg/ml). In children with two episodes assessed, although there was a close correlation of FEV(1) and FVC between exacerbations (before antibiotics), no significant correlation was seen for IL-8, TNF-alpha, or IL-10 measured in both sets of samples at any sample point (indeed, a discordant response was seen between sample points in the two exacerbations). Although FEV(1) temporarily improves in response to admission for IV antibiotics, no such response is seen in sputum cytokine values. In addition, assessment of cytokines in subsequent exacerbations does not show a similar pattern of response to treatment.

Chorioamnionitis and increased neonatal lung lavage fluid matrix metalloproteinase-9 levels: implications for antenatal origins of chronic lung disease

OBJECTIVE

Matrix metalloproteinase-9 (MMP-9) degrades type IV collagen, the major constituent of lung basement membrane. We studied the effects of chorioamnionitis and antenatal corticosteroids on bronchoalveolar lavage (BAL) fluid levels of MMP-9, and its inhibitor, TIMP-1 in preterm infants.

STUDY DESIGN

A prospective study was performed on serial BAL samples from 79 ventilated preterm infants at less than 33 weeks' gestation, 18 of whom were from pregnancies complicated by chorioamnionitis. MMP-9 levels were measured by gelatin zymography and TIMP-1 by enzyme-linked immunosorbent assay, and the median value for each infant was calculated. The presence and severity of chorioamnionitis were defined histologically.

RESULTS

BAL fluid MMP-9 levels were higher in preterm infants in the chorioamnionitis group (86 [29-518] vs 13 [3-43] ng/mL, P =.001), and levels increased stepwise with the increasing severity of chorioamnionitis. Antenatal corticosteroids had no effect on median MMP-9 levels. Infants in the chorioamnionitis group were more likely to have chronic lung disease (CLD) develop (55% vs 28%, P <.05). TIMP-1 levels were no different between groups.

CONCLUSION

Chorioamnionitis is associated with increased lung type IV collagenase levels in the ventilated preterm infant. Antenatal lung inflammation with up-regulation of MMP-9 may be important in the pathogenesis of CLD.

Bronchoalveolar lavage surfactant protein a, B, and d concentrations in preterm infants ventilated for respiratory distress syndrome receiving natural and synthetic surfactants

Surfactant proteins (SPs) play an important role in surfactant metabolism and function. Understanding their relative contribution to clinical outcome remains incomplete. Exogenous surfactants differ in their SP content and physiologic effects. The aims of this study were to measure bronchoalveolar lavage (BAL) SP concentrations from preterm infants ventilated for respiratory distress syndrome and to assess their association with clinical outcome. Fifty preterm infants randomized to receive a natural or synthetic surfactant were lavaged each day for the first week and twice weekly thereafter using a standardized nonbronchoscopic technique. BAL SP-A, SP-B, and SP-D concentrations were measured using ELISA. Median BAL SP-A, SP-B, and SP-D concentrations for the whole cohort rose significantly during the first postnatal week (p < 0.05). SP-A concentration did not differ between outcome groups. BAL SP-B concentration rose significantly in lungs that were not supplemented with SP-B. Infants dying had significantly lower BAL SP-B concentrations on d 2 and 6 compared with survivors. BAL SP-D concentrations were significantly lower on d 2 and 3 among infants in supplemental oxygen on d 28 compared with those in air. BAL SP-A and SP-D concentrations did not differ significantly between infants randomized to receive a natural or synthetic surfactant. Lower BAL SP-B and SP-D but not SP-A concentrations were associated with worse clinical prognosis.

Differential cytology of bronchoalveolar lavage fluid in asthmatic children

Although asthma usually begins in childhood, limited information is available as to the inflammatory reaction of asthmatic children compared to adults and the influence of age. We investigated the cytology of bronchoalveolar lavage fluid (BALF) in 39 newly diagnosed wheezy children (minimum of 3 wheezing episodes during last 6 months): 21 allergic and 18 nonallergic subjects. None had received antiinflammatory treatment. Bronchoalveolar lavage (BAL) was performed, instilling 0.5 ml.kg(-1) body weight of warmed saline in 4 successive fractions. The first 2 aliquots (BALF 1) were pooled for microbiology and cytology, and the last 2 (BALF 2) for cytology only. Recovery correlated inversely with age, the most significant being for BALF 2 (r = -0.52, P = 0.001). Children under 2 years of age had larger amounts of ciliated columnar and goblet cells (P = 0.0074). Other cell types did not show age dependency. Differential cytology was characterized by a high number of creola bodies, bronchial epithelial cells (M = 68 x 10(3).ml(-1), R = 5-349), and neutrophils (M = 92 x 10(3).ml(-1), R = 0-1,257). Eosinophils were the only cells distinguishing allergic from nonallergic subjects (P = 0.003). The 16 children with positive microbiology had more neutrophils than the noninfected (P = 0.008), the latter still having more neutrophils than found in adults. These data suggest a limited age dependency in BALF cytology. Differential cytology in BALF might be helpful in differentiating asthma in children. Neutrophil inflammation might be more important than in adults.

Human metapneumovirus in severe respiratory syncytial virus bronchiolitis

Reverse transcription-polymerase chain reaction was used to detect segments of the M (matrix), N (nucleoprotein), and F (fusion) genes of human metapneumovirus in bronchoalveolar fluid from 30 infants with severe respiratory syncytial virus bronchiolitis. Seventy percent of them were coinfected with metapneumovirus. Such coinfection might be a factor influencing the severity of bronchiolitis.

Antioxidants and oxidative stress in BAL fluid of atopic asthmatic children

Earlier studies in adults have indicated that increased oxidative stress may occur in the blood and airways of asthmatic subjects. Therefore the aim of this study was to compare the concentrations of antioxidants and protein carbonyls in bronchoalveolar lavage fluid of clinically stable atopic asthmatic children (AA, n = 78) with our recently published reference intervals for nonasthmatic children (C, n = 124). Additionally, lipid peroxidation products (malondialdehyde) in bronchoalveolar lavage fluid and several antioxidants in plasma were determined. Bronchoalveolar lavage concentrations (median and interquartile range) of ascorbate [AA: 0.433 (0.294-0.678) versus C: 0.418 (0.253-0.646) micromol/L], urate [AA: 0.585 (0.412-0.996) versus C: 0.511 (0.372-0.687) micromol/L], alpha-tocopherol [AA: 0.025 (0.014-0.031) versus C: 0.017 (0.017-0.260) micromol/L], and oxidized proteins as reflected by protein carbonyls [AA: 1.222 (0.970-1.635) versus C: 1.243 (0.813-1.685) nmol/mg protein] were similar in both groups (p > 0.05 in all cases). The concentration of protein carbonyls correlated significantly with the number of eosinophils, mast cells, and macrophages in AA children only. Concentrations of oxidized proteins and lipid peroxidation products (malondialdehyde) correlated significantly in AA children (r = 0.614, n = 11, p = 0.044). Serum concentrations of ascorbate, urate, retinol, alpha-tocopherol, beta-carotene, and lycopene were similar in both groups whereas alpha-carotene was significantly reduced in asthmatics. Overall, increased bronchoalveolar lavage eosinophils indicate ongoing airway inflammation, which may increase oxidatively modified proteins as reflected by increased protein carbonyl concentrations.

Peptide growth factors in tracheal aspirates of mechanically ventilated preterm neonates

Basic fibroblast growth factor (bFGF or FGF-2), vascular endothelial growth factor (VEGF), and endothelin-1 (ET-1) are peptide growth factors (PGF) mediating normal lung development, maturation, injury, and repair. These PGF may therefore be involved in the pathogenesis of bronchopulmonary dysplasia (BPD). We hypothesized that elevated levels of these PGF in tracheal aspirates would be associated with a) BPD and/or death; b) markers of cell injury and apoptosis; and c) chorioamnionitis, a risk factor for BPD. Tracheal aspirates collected in 29 preterm (<34 wk gestation, 500-2000 g birth weight), mechanically ventilated infants on d 1 of life were assayed for PGF and histone-associated DNA fragments by ELISA and for LDH by enzyme assay. Clinical and pathologic examination was performed for chorioamnionitis. BPD was defined as oxygen requirement/mechanical ventilation at 28 d postnatal age. The birth weight (mean +/- SE) was 1009 +/- 85 g and median gestational age was 26 wk (range, 22-33). Eighteen infants died or developed BPD. bFGF levels were elevated in infants who died or developed BPD [median (25%,75%) level of 36 (23, 44) pg/mL versus 14 (6, 30) in the survivors without BPD, p = 0.01]. bFGF levels correlated with apoptosis (r = 0.73, p < 0.001) and LDH levels (r = 0.59, p < 0.001). VEGF and ET-1 levels were not associated with apoptosis or with BPD/death. PGF levels were not associated with chorioamnionitis. We conclude that elevated bFGF levels in the preterm trachea correlate with BPD/death and markers of cell injury and apoptosis but not with chorioamnionitis. We speculate that bFGF may play a role in the development of BPD.

Thrombin contributes to bronchoalveolar lavage fluid mitogenicity in lung disease of the premature infant

Chronic lung disease of prematurity (CLD) is a common consequence of neonatal respiratory distress syndrome (RDS) and is characterized by pulmonary fibrosis. Increased thrombin activity in the alveolar compartment is associated with pulmonary fibrosis in adults and animals, and contributes to bronchoalveolar lavage (BAL) fluid mitogenicity for fibroblasts. We hypothesized that BAL fluid from infants who develop CLD contains increased mitogenic activity for lung fibroblasts compared to BAL fluid from resolving RDS, and that increased thrombin levels contribute to this activity. Sequential BAL (postnatal days 2-14) was obtained from 37 premature infants who were ventilated for RDS. Twenty-six infants developed CLD, whereas 11 resolved. BAL fluid mitogenic activity was determined in a proliferation assay, using human fetal lung fibroblasts. The contribution of thrombin to mitogenic activity was determined using the thrombin inhibitor PPACK. Furthermore, thrombin levels in BAL fluid were measured using a specific substrate to detect thrombin activity and by measuring thrombin-antithrombin III complex (TATIII). BAL fluid mitogenic activity was comparable between CLD and RDS (CLD, 33% proliferation on day 2 to 41% on day 14; RDS, 21% on day 2 to 54% on day 7). Thrombin inactivation by PPACK completely inhibited mitogenic activity in BAL samples obtained on days 2 and 4 (CLD, P < 0.001 on days 2 and 4; RDS, P < 0.05 on day 4). From day 7 onwards, inhibition of thrombin only partly reduced (P < 0.05) CLD BAL fluid mitogenic activity, indicating that other mitogenic factors contribute as well. Surprisingly, thrombin activity and TATIII were decreased in BAL fluid from CLD compared with RDS patients on days 2 and 4. In conclusion, our study shows that BAL fluid from infants with and without CLD development is equally mitogenic for lung fibroblasts, and that thrombin is a major mitogen in these samples. This suggests that fibroproliferation may occur early in the lungs from infants with both CLD and RDS, and that thrombin contributes to this.

Fibrobroncoscopia en el niño con ventilación mecánica

Fiberoptic bronchoscopy can be performed at the patient's bedside. This technique allows direct visualization of the upper and lower airways up to the segmental and subsegmental bronchi. Its most frequent indications are airway examination ot evaluate damage produced by toxins or the endotracheal tube, patency of the endotracheal tube and extubation failure. It is also used to obtain microbiological samples, facilitate intubation when difficult, aspirate airway sections or mucus plugs, perform bronchoalveolar lavage and administer drugs. With prior preparation, adequate monitoring and sedation, material according to the size of the patient and correct techniques, there are few complications. However, the procedure can produce trauma and obstruction of the airway, bronchial hemorrhage, barotrauma, loss of alveolar recruitment, bronchospasm, hypoxemia, bradycardia, and bronchopulmonary infection.

Aspiración endotraqueal, cepillado y lavado broncoalveolar

The aim of endotracheal aspiration is to eliminate secretions in patients with an artificial airway. All children with mechanical ventilation must undergo this procedure periodically. The frequency of aspiration depends on the type and quantity of the respiratory secretions and on the patient's clinical status. Aspiration should be performed by two people to maintain a greater degree of asepsis and to optimize stability of the airway and ventilation. Closed aspiration systems are available that allow aspiration without the need to disconnect the patient through a single probe that is constantly protected by a plastic sleeve and isolated from external environment. The most important risks of endotracheal aspiration are hypoxemia, mucosal injury, bronchospasm, arrhythmias, perforation of the airway with development of pneumothorax, accidental extubation, and infections. Bronchial brushing with a protected catheter and brochoalveolar lavage are used to analyze pulmonary infections. These techniques can be performed blind or through fibrobronchoscopy. They can also be used for the diagnosis of noninfectious pulmonary diseases such as alveolar proteinosis, alveolar hemorrhage or histiocytosis. Their adverse effects are similar to those of endotracheal aspiration.

Detectable IL-8 and IL-10 in bronchoalveolar lavage fluid from preterm infants ventilated for respiratory distress syndrome

Pro-inflammatory cytokines such as IL-8 play an important role in the inflammatory response to neonatal airway injury. Difficulty in detecting counter-regulatory cytokines such as IL-10 in lavage fluid from preterm infants led to the suggestion that its deficit may be a factor in the etiology of chronic lung disease of prematurity (CLD). The aim of the study was to determine IL-8 and IL-10 concentrations in lavage fluid from preterm infants ventilated for respiratory distress syndrome. Fifty infants <30 wk gestation were studied who had been randomized to receive a natural or synthetic surfactant. Lavage samples were collected daily for the first week and twice weekly thereafter. Samples were immediately centrifuged and stored at -70 degrees C. Cytokine concentrations were quantified in duplicate using commercially available sandwich ELISA kits. Lavage IL-10 concentration, at a minimum initially, rose significant over the first five postnatal days (p = 0.009). In the same samples, lavage IL-8 concentrations rose significantly over the first postnatal week (p < 0.001), the rise preceding that of IL-10. Infants dying or developing CLD had a significant early rise in both cytokine concentrations. Compared with infants developing CLD, lavage IL-10 concentrations were significantly higher on d 1 among those not developing CLD but significantly lower on d 4 (p < 0.05). To conclude, IL-10 is detectable in lavage fluid from ventilated preterm infants and its concentrations rise significantly over the first five postnatal days. In the same samples, IL-8 concentration also rises and this increase precedes the rise in IL-10.

Invasive monitoring of airway inflammation

What we know: Ethical concerns have limited research involving invasive bronchoscopy techniques in young children. No longitudinal studies have been conducted to compare the findings of bronchial biopsy or bronchoalveolar lavage in young children with transient episodic wheeze versus asthma. Children with atopic asthma have more airway eosinophils and mast cells than children with viral-associated wheeze. Both neutrophilic and eosinophilic patterns of inflammation are present in asthma. What we need to know: Can we establish robust normal values for tissue and fluid samples obtained at bronchoscopy or bronchoalveolar lavage? Do biopsy specimens taken at the carina tell us about the pathological processes occurring in asthma? Can we use invasive procedures to predict which children with wheeze will continue to wheeze and develop a classical asthma phenotype? Can we use invasive procedures to guide asthma therapy? Can we expect airway inflammation to resolve with anti-inflammatory medication? Can we correlate invasive with non-invasive measures of inflammation? Can we use our understanding of pro- and anti-inflammatory pathways to develop new therapeutic interventions? Is there a presymptomatic phase of inflammation?

Bronchoalveolar cells in children < 3 years old with severe recurrent wheezing

STUDY OBJECTIVE

To determine the cell profile of BAL from infants with severe recurrent wheezing who were not acutely ill at the time of investigation, suggesting an ongoing inflammation.

DESIGN AND PATIENTS

In a retrospective study, we determined BAL cell profiles for 83 children with wheezing aged 4 to 32 months (mean +/- SD, 11.3 +/- 5.5 months). Fiberoptic bronchoscopy was performed in children with severe recurrent wheezy bronchitis unresponsive to inhaled steroids. These children were compared with 17 children aged 6 to 36 months (mean, 15.1 +/- 7.5 months) with various nonwheezing pulmonary diseases. Children were included as control subjects if they had no endobronchial inflammation and no atopy.

RESULTS

The BAL cell profile of young children with wheezing typically includes a significantly higher cell count (mean, 644.4 +/- 956.8 x 10(3)/mL vs 313 +/- 203.2 x 10(3)/mL, p = 0.008), a significantly higher percentage of neutrophils (mean, 9 +/- 12.1% vs 2.1 +/- 2.2%, p = 0.003), and a higher neutrophil count (mean, 43.2 +/- 81.6 x 10(3)/mL vs 7.9 +/- 11.8 x 10(3)/mL, p = 0.003), as compared with control subjects. The larger number of neutrophils in children with wheezing was not correlated with bacterial or viral infection, or with age, sex, or atopic status. In contrast to the situation in asthmatic adults, eosinophil levels were not higher in children with wheezing than in control subjects (mean, 0.09 +/- 0.27% vs 0.08 +/- 0.25%).

CONCLUSION

Neutrophil-mediated inflammation in the airways appears to better characterize severe recurrent wheezing in children < 3 years old.

Pediatric flexible airway endoscopy

Flexible airway endoscopy has been used in clinical and research investigations of pediatric airway and pulmonary disorders for nearly 25 years. Not only has clinical use of the flexible bronchoscope improved our evaluation and management of a variety of airway and pulmonary diseases in children, but also research investigations using lavage and biopsy specimens obtained with the flexible bronchoscope have contributed extensively to our understanding of lung inflammation and infection. Improvements and new developments in fiberoptic endoscope technology, training of airway endoscopists, preoperative and sedative medications, patient monitoring, and airway endoscopic techniques, as well as adjunctive minimally invasive and noninvasive diagnostic modalities, continue to refine and enhance the pediatric clinical and research applications of flexible airway endoscopy.

Fibroblast mitogenic activity of lung lavage fluid from infants with chronic lung disease of prematurity

BACKGROUND

Lung fibrosis is thought to be important in chronic lung disease of prematurity (CLD).

METHODS

Fibroblast proliferative activity was assessed in 207 bronchoalveolar lavage fluid (BALF) samples from 43 infants. Sixteen developed CLD (birth weight 765 g (630-1230), gestation 26.5 weeks (23-29)), 18 developed respiratory distress syndrome (RDS) (birth weight 1415 g (430-4160), gestation 31 weeks (23-39)), and nine control infants (birth weight 2110 g (900-3720), gestation 32 weeks (26-41)) received mechanical ventilation for non-pulmonary reasons.

RESULTS

The fibroblast proliferative activity relative to 10% fetal calf serum was 64-75% in infants with CLD, 55-86% in the RDS group, and 42-68% in control infants during the first 5 weeks of life. Only at day 3 was there a difference between the groups (CLD 72% v control 42%, p < 0.01; RDS 63% v control 42%, p < 0.05). With the use of neutralising antibodies, platelet derived growth factor BB (PDGF-BB) and epidermal growth factor were undetectable, and insulin-like growth factor I (IGF-I) accounted for 14% (p < 0.05) and 11% (p < 0.005) of BALF mitogenic activity from the RDS and CLD groups respectively.

CONCLUSIONS

The mitogenic activity of BALF was similar in the three groups studied and was only partially accounted for by IGF-I. Growth factors other than PDGF-BB and IGF-I contribute significantly to this process.

Oxidative stress in lavage fluid of preterm infants at risk of chronic lung disease

There is evidence that oxidative stress plays a role in the development of chronic lung disease (CLD), with immature lungs being particularly sensitive to the injurious effect of oxygen and mechanical ventilation. We analyzed total ascorbate, urate, and protein carbonyls in 102 bronchoalveolar lavage fluid samples from 38 babies (33 preterm, 24-36 wk gestation; 5 term, 37-39 wk gestation). Preterm babies had significantly decreasing concentrations of ascorbate, urate, and protein carbonyls during the first 9 days of life (days 1-3, 4-6, and 7-9, Kruskal-Wallis ANOVA: P = 0.016, P < 0.0001, and P = 0.010, respectively). Preterm babies had significantly higher protein carbonyl concentrations at days 1-3 and 4-6 (P = 0.005 and P = 0.044) compared with term babies. Very preterm babies (24-28 wk gestation) had increased concentrations of protein carbonyls at days 4-6 (P = 0.056) and significantly decreased ascorbate concentrations at days 4-6 (P = 0.004) compared with preterm babies (29-36 wk gestation). Urate concentrations were significantly elevated at days 1-3 (P = 0.023) in preterm babies who subsequently developed CLD. This study has shown the presence of oxidative stress in the lungs of preterm babies during ventilation, especially in those who subsequently developed CLD.

Repeatability of cellular constituents and cytokine concentration in fluid obtained by non-bronchoscopic bronchoalveolar lavage of infants receiving extracorporeal oxygenation

BACKGROUND

Since few studies have assessed the repeatability of non-bronchoscopic bronchoalveolar lavage (NB-BAL), we compared cellular counts and cytokine concentrations in fluid obtained by standardised NB-BAL from each side of 20 intubated infants receiving extracorporeal membrane oxygenation (ECMO).

METHODS

Total cell counts were obtained from 95 paired lavages and 77 pairs were suitable for differential counts and measurement of cytokine concentrations.

RESULTS

Moderate correlation was noted between the two sides for most cell types including total cell counts and percentages of neutrophils and macrophages (R=0.70-0.84) and for cytokine concentrations (IL-8 R=0.78, IL-6 R=0.75, TNF-alpha R=0.64, all p< or =0.001). Using Bland-Altman analysis the mean difference between the two sides approached zero for cellular constituents (total cell counts mean difference 1.7, limits of agreement -187.5 to +190.9 x 10(4)/ml; percentage neutrophils -3.9%, -41.5% to +33.6%; percentage macrophages 3.9%, -33.8% to +41.6%) but tended to be greater on the right for logarithmically transformed cytokine measurements (IL-8: left/right ratio 0.74, limits of agreement 0.12 to 5.45, IL-6: 0.93, 0.09 to 5.87, and TNF-alpha: 0.93, 0.27 to 3.16). Using linear regression with random effects to assess the variability, only the infant's age appeared to influence the cellular results but, for cytokines, only the volume retrieved affected the variability. The magnitude of the measurements, the underlying disease, the operator's experience, days on ECMO, or survival did not affect the variability.

CONCLUSION

Measurements obtained by NB-BAL need to be interpreted with caution and strongly suggest that normalisation for the dilutional effects of saline is essential.

Oxidative stress and increased type-IV collagenase levels in bronchoalveolar lavage fluid from newborn babies

Oxidative stress may increase lung permeability by up-regulation of matrix-metalloproteinase-9 (MMP-9), a type-IV collagenase that can disrupt alveolar basement membranes. We have compared a marker of oxidative stress (protein carbonyl residues) with levels of MMP-9 and its inhibitor, tissue inhibitor of metalloproteinase-1 (TIMP-1), in bronchoalveolar lavage samples from newborn babies. Bronchoalveolar lavage samples (n = 87, two from each time point) were taken in the first 6 postnatal days from 41 ventilated babies: 18 of <29 wk gestation, 10 of 29-36 wk, 9 term with persistent fetal circulation, and 4 term without lung disease. Respiratory disease severity at the time of bronchoalveolar lavage was assessed using the arterial-alveolar oxygen tension ratio. One sample from each time point was used for the measurement of MMP-9 by zymography and TIMP-1 by ELISA. The second sample was used to measure carbonyl group concentrations, also using an ELISA. Correlations were calculated between protein carbonyls, arterial-alveolar oxygen tension ratio, and MMP-9 and TIMP-1 concentrations. Significant correlations were found between carbonyl concentrations and arterial-alveolar oxygen tension ratio (r = -0.325, p = 0.0031, n = 81), MMP-9 (r = 0.331, p < 0.0029, n = 79), and TIMP-1 (r = 0.436, p < 0.0001, n = 87). Worsening respiratory disease in newborn babies is associated with increased carbonyl concentrations in neonatal bronchoalveolar lavage fluid, and these correlated with MMP-9 and TIMP-1 levels. Increased oxidative stress may damage the lung by increasing type-IV collagenase activity, causing disruption of the extracellular matrix.

Persistent wheezing in very young children is associated with lower respiratory inflammation

Despite advances in understanding the pathophysiology of asthma, morbidity and mortality in pediatrics continue to rise. Little is known about the initiation and chronicity of inflammation resulting in asthma in this young population. We evaluated 20 "wheezing" children (WC) (median age 14.9 mo) with a minimum of two episodes of wheezing or prolonged wheezing > or = 2 mo in a 6-mo period with bronchoscopy and bronchoalveolar lavage (BAL). Comparisons were made with six normal controls (NC) (median age 23.3 mo) undergoing general anesthesia for elective surgery. BAL fluid cell counts and differentials were determined. The eicosanoids, leukotriene (LT) B(4), LTE(4), prostaglandin (PG)E(2), and 15-hydroxyeicosatetraenoic acid (HETE) and the mast cell mediators, beta-tryptase and PGD(2), were evaluated by enzyme immunoassay (EIA). WC had significant elevations in total BAL cells/ml (p = 0.01), as well as, lymphocytes (LYMPH, p = 0.007), macrophages/monocytes (M&M, p = 0.02), polymorphonuclear cells (PMN, p = 0.02), epithelial cells (EPI, p = 0.03), and eosinophils (EOS, p = 0.04) compared with NC. Levels of PGE(2) (p = 0.0005), 15-HETE (p = 0.002), LTE(4) (p = 0.04), and LTB(4) (p = 0.05) were also increased in WC compared with NC, whereas PGD(2) and beta-tryptase were not. This study confirms that inflammation is present in the airways of very young WC and may differ from patterns seen in adults with asthma.

Type I collagenases in bronchoalveolar lavage fluid from preterm babies at risk of developing chronic lung disease

OBJECTIVE

To assess whether increased collagenolysis precedes severe chronic lung disease (CLD).

METHODS

Matrix metalloproteinase-1 (MMP-1) and MMP-8 (enzymes that degrade type I collagen, the main structural protein of lung extracellular matrix) were measured by enzyme linked immunosorbent assay in 100 bronchoalveolar lavage samples taken during the first 6 postnatal days from 45 ventilated preterm babies < 33 weeks gestation. The median value for each baby was calculated. CLD was defined as an oxygen requirement after the 36th week after conception.

RESULTS

MMP-8 levels in bronchoalveolar lavage fluid were higher (median 13 ng/ml) in 20 babies who developed CLD than in 25 without CLD (median 2 ng/ml). No MMP-1 was detected in any sample.

CONCLUSIONS

MMP-8 can be detected in bronchoalveolar lavage fluid from preterm babies, and higher levels are found in those who later develop CLD. MMP-8 may contribute to lung injury that occurs as a prelude to CLD.

Antioxidants and protein carbonyls in bronchoalveolar lavage fluid of children: normal data

Antioxidant-oxidant imbalances in bronchoalveolar lavage fluid (BAL) are thought to contribute to oxidative stress in respiratory disease. However, normal reference ranges for BAL antioxidants and oxidized proteins in children are not available. In this study, we recruited 124 children attending for elective surgery for a noninflammatory condition; 83 were nonasthmatic, nonatopic (N) and 41 were nonasthmatic, atopic (NA). A nonbronchoscopic lavage was performed and ascorbate, uric acid, alpha-tocopherol, and protein carbonyl (as a measure of oxidative damage) concentrations were determined in BAL fluid. The 95% reference range was 0.112-1.897 micromol/L for ascorbate, 0.149-2.163 micromol/L for urate, 0.0029-0.066 micromol/L for alpha-tocopherol, and 0.280-4.529 nmol/mg for protein carbonyls in BAL fluid. Age, gender, and exposure to environmental tobacco smoke did not affect the concentration of ascorbate, urate, alpha-tocopherol, or protein carbonyls. However, in multiple linear regression analyses, the type of home heating (glass-fronted fires or oil-fired central heating) was found to influence ascorbate and urate concentrations in the BAL fluid (ss-coefficient for ascorbate: 0.445, p = 0.031; for urate: 0.114, p = 0.001). There was no significant difference between the N and NA group in BAL fluid concentrations of ascorbate, urate, or protein carbonyls. The alpha-tocopherol concentration was significantly increased in the NA group (p = 0.037). Uric acid and alpha-tocopherol concentrations in BAL fluid and serum were not correlated. Intriguingly, serum and BAL ascorbate concentrations were significantly correlated (r = 0.297, p = 0.018, n = 63), which may offer an explanation for why supplementing the diet with vitamin C can improve asthma symptoms. Further studies will investigate the role of BAL antioxidant concentrations in children with inflammatory respiratory diseases.

Pediatric bronchoscopy

Diagnostic flexible endoscopy for pediatric respiratory diseases is performed in many centers. Technical advances have resulted in performance of interventional bronchoscopies, and new diagnostic indications are being explored. Indications with documented clinical benefit include congenital or acquired progressive or unexplained airway obstruction. Pulmonary infections in immunodeficient children who do not respond to empirical antibiotic treatment may be diagnosed by bronchoscopy and bronchoalveolar lavage (BAL). The potential usefulness of bronchoscopy and BAL for managing chronic cough, wheeze, or selected cases with asthma or cystic fibrosis requires further study. The use of transbronchial biopsies (TBB) is established in pediatric lung transplantation. The role of TBB in the diagnosis of chronic interstitial lung disease in children remains to be determined. For a number of interventional applications, rigid endoscopy is required, and pediatric bronchoscopists should be trained in its use. Complications in pediatric bronchoscopy are rare, but severe nosocomial infection or overdosing with local anesthetics has occurred. The issues of quality control, video documentation, interobserver variability of findings, and educational standards will have to be addressed in the future as bronchoscopy use becomes less restricted to only large pediatric pulmonary units.