Deleted in Malignant Brain Tumors 1 (DMBT1) is present in hyaline membranes and modulates surface tension of surfactant.

BACKGROUND: Deleted in Malignant Brain Tumors 1 (DMBT1) is a secreted scavenger receptor cysteine-rich protein that binds various bacteria and is thought to participate in innate pulmonary host defense. We hypothesized that pulmonary DMBT1 could contribute to respiratory distress syndrome in neonates by modulating surfactant function. METHODS: DMBT1 expression was studied by immunohistochemistry and mRNA in situ hybridization in post-mortem lungs of preterm and full-term neonates with pulmonary hyaline membranes. The effect of human recombinant DMBT1 on the function of bovine and porcine surfactant was measured by a capillary surfactometer. DMBT1-levels in tracheal aspirates of ventilated preterm and term infants were determined by ELISA. RESULTS: Pulmonary DMBT1 was localized in hyaline membranes during respiratory distress syndrome. In vitro addition of human recombinant DMBT1 to the surfactants increased surface tension in a dose-dependent manner. The DMBT1-mediated effect was reverted by the addition of calcium depending on the surfactant preparation. CONCLUSION: Our data showed pulmonary DMBT1 expression in hyaline membranes during respiratory distress syndrome and demonstrated that DMBT1 increases lung surface tension in vitro. This raises the possibility that DMBT1 could antagonize surfactant supplementation in respiratory distress syndrome and could represent a candidate target molecule for therapeutic intervention in neonatal lung disease.

Resting energy expenditure in children with neonatal chronic lung disease and obstruction of the airways.

Children with history of broncho-pulmonary dysplasia (BPD) often suffer from growth failure and lung sequelae. The main objective of this study was to test the role of pulmonary obstruction on resting energy expenditure (REE) and nutritional status in BPD. Seventy-one children with BPD (34 boys and 37 girls) and 30 controls (20 boys and 10 girls) aged 4-8 years were enrolled. Body composition was assessed by bio-impedancemetry measurements; REE was measured by indirect calorimetry. Predicted REE was calculated using the Schofield equation. The population of children with BPD was divided into three groups: children without obstruction of the airways, children with moderate obstruction of the airways, and children with severe obstruction. Children with BPD were significantly smaller and leaner than controls. Altered body composition (reduction of fat mass) was observed in BPD children that suffered from airway obstruction. REE was significantly lower in children with BPD compared to controls, but when adjusted for weight and fat-free mass no significant difference was observed irrespective of pulmonary status. Airway obstruction in children with BPD does not appear to be associated with an increased REE. Moreover altered REE could not explain the altered nutritional status that is still observed in BPD in later childhood. This supports the hypothesis that body composition and pulmonary function in BPD in later childhood are fixed sequelae originating from the neonatal period.

Substrate utilization and kinetics of surfactant metabolism in evolving bronchopulmonary dysplasia.

OBJECTIVES: To use stable isotopically labeled precursors of pulmonary surfactant phospholipids to measure precursor utilization and surfactant turnover in premature infants who required mechanical ventilation at birth, 2 weeks, and >4 weeks of age. STUDY DESIGN: Infants of < or =28 weeks' gestation received simultaneous 24-hour intravenous infusions of [1,2,3,4-13C4] palmitate and [1-13C1] acetate at birth, 2 weeks, and > or =4 weeks of life. Disaturated phospholipids were extracted from sequential tracheal aspirate samples obtained over a period of 2 weeks. Fractional catabolic rate (a measure of total turnover) and the fractional synthetic rates from plasma palmitate and de novo synthesis (acetate) were measured. RESULTS: The fractional catabolic rate increased from 25.3% +/- 7.0% per day at birth to 53.8% +/- 14.4% per day at 4 weeks (P=.001). The combined contribution from plasma palmitate and de novo synthesis to total synthesis increased from 44.2% +/- 19.8% at birth to 85.2% +/- 32.8% at 4 weeks (P=.03). CONCLUSIONS: Total surfactant turnover increased in premature infants with evolving bronchopulmonary dysplasia. The increasing contributions from acetate and plasma palmitate suggest a decrease in surfactant phospholipid recycling.

Nuclear factor kappaB activation in pulmonary leukocytes from infants with hyaline membrane disease: associations with chorioamnionitis and Ureaplasma urealyticum colonization.

Unresolved pulmonary inflammation in hyaline membrane disease (HMD) may be a precursor to the development of chronic lung disease of early infancy. We investigated whether nuclear factor kappaB (NF-kappaB), a transcription factor that regulates the inflammatory process, is activated in pulmonary leukocytes in tracheal aspirates from premature infants with HMD. A total of 172 samples were obtained from 59 infants, two thirds of whom showed NF-kappaB activation in lung neutrophils and macrophages on at least one occasion. Infants who had activated NF-kappaB showed elevated tumor necrosis factor-alpha concentrations in their tracheal aspirates. These infants also required a longer period of mechanical ventilation support. Almost half of the infants with HMD had antenatal exposure to chorioamnionitis on the basis of placental histopathologic examination. These infants had evidence of activated NF-kappaB and elevated cytokines and were more likely to have Ureaplasma urealyticum colonization in their airways. Together, these observations suggest that NF-kappaB activation in pulmonary leukocytes may be involved in the lung inflammatory process in infants with HMD.

Immunohistochemical localization of epidermal growth factor receptor (EGF-R) in normal and diseased newborn lung tissues.

The distribution of EGF receptors (EGF-R) was examined in normal, hyaline membrane diseased and pneumonic newborn lung tissues by immunohistochemical methods under the light microscope. The PAP technique with polyclonal antibodies was performed to demonstrate the EGF receptor localisation in these tissues. Strong EGF-R reactivity was observed on bronchiolar epithelium and type I and type II alveolar cells in normal newborn lung tissues; whereas, poor reactivity was observed in alveolar macrophages. On the other hand, strong immunoreactivity was detected in type I alveolar cells and alveolar macrophages in hyaline membrane disease, but no reactivity was present in type II alveolar cells. The strongest immunoreactivity was observed in alveolar macrophages of newborn pneumonic lung tissues. In conclusion, the most meaningful form of reactivity was observed in normal newborn lung tissues of airway track and respiration area. This result is related with the maturation of the lungs after birth.

Continuous tracheal gas insufflation enables a volume reduction strategy in hyaline membrane disease: technical aspects and clinical results.

OBJECTIVE: Instrumental dead space wash-out can be used to improve carbon dioxide clearance. The aim of this study was to define, using a bench test, an optimal protocol for long-term use, and to assess the efficacy of this technique in neonates. DESIGN: A bench test with an artificial lung model, and an observational prospective study. Dead space wash-out was performed by continuous tracheal gas insufflation (CTGI), via six capillaries molded in the wall of a specially designed endotracheal tube, in 30 preterm neonates with hyaline membrane disease. SETTING: Neonatal intensive care unit of a regional hospital. RESULTS: The bench test study showed that a CTGI flow of 0.5 l/ min had the optimal efficacy-to-side-effect ratio, resulting in a maximal or submaximal efficacy (93 to 100%) without a marked increase in tracheal and CTGI circuit pressures. In the 30 newborns, 15 min of CTGI induced a significant fall in arterial carbon dioxide tension (PaCO2), from 45 +/- 7 to 35 +/- 5 mmHg (p = 0.0001), and in 14 patients allowed a reduction in the gradient between Peack inspirating pressure and positive end-expiratory pressure from 20.8 +/- 4.6 to 14.4 +/- 3.7 cmH2O (p < 0.0001) while keeping the transcutaneous partial pressure of carbon dioxide constant. As predicted by the bench test, the decrease in PaCO2 induced by CTGI correlated well with PaCO2 values before CTGI (r = 0.58, p < 0.002) and with instrumental dead space-to-tidal volume ratio (r = 0.54, p < 0.005). CONCLUSION: CTGI may be a useful adjunct to conventional ventilation in preterm neonates with respiratory disease, enabling an increase in CO2 clearance or a reduction in ventilatory pressure.

[18F]fluorodeoxyglucose uptake in neonatal acute lung injury measured by positron emission tomography.

The objective of this study was to evaluate positron emission tomography (PET) of [18F]fluorodexoyglucose (18FDG) uptake as a measure of neonatal acute lung injury. Inasmuch as intrapulmonary sequestration of neutrophils is a hallmark of acute lung injury, quantification of neutrophil activity using 18FDG may offer a novel, in vivo technique to examine the progression and resolution of this disease. Ten newborn piglets were studied: six received bronchoalveolar lavage followed by 4 h of high pressure ventilation of create acute lung injury. Four healthy piglets served as controls. 18FDG (0.8 mCi/kg; 29.6 MBq) was given i.v. and PET (ECAT 953/31, Siemens) was performed for 90 min. During PET, all animals were sedated, paralyzed, and ventilated to maintain normal blood gases. The time course of radioactivity in lung regions and in plasma was used to calculate the rate constant for the metabolic trapping of 18FDG in tissue according to the method of C. S. Patlak. Median 18FDG influx constants were significantly higher in injured piglets (0.0187 min-1) than in control piglets (0.0052 min-1) (p < 0.01). Moreover, consistent with the 18FDG uptake data, injured piglets had moderate to severe injury on lung histology whereas control piglets had only slight and focal histologic changes. We conclude that PET of 18FDG uptake is an accurate, readily repeatable in vivo measure of neonatal acute lung injury.

Ontogeny of Clara cell-specific protein and its mRNA: their association with neuroepithelial bodies in human fetal lung and in bronchopulmonary dysplasia.

Clara cell-specific 10-KD protein (CCSP) is an abundant product of nonciliated bronchiolar epithelial (Clara) cells in the lung. We have determined the temporal-spatial distribution of CCSP and its mRNA in developing human lung and in neonatal lung disease, using immunohistochemistry and in situ hybridization. CCSP immunoreactivity was found in nonciliated bronchiolar epithelial cells from 12 weeks of gestation onward. Tracheal and bronchial epithelia showed positive immunoreactivity at each gestational week after 15 weeks and 14 weeks, respectively. CCSP mRNA was seen in the bronchial and bronchiolar epithelia from 16 weeks onward and was detected in the trachea from 19 through 23 weeks of gestation. CCSP immunoreactivity and mRNA were present in nonciliated single cells of bronchial and bronchiolar epithelia in fetuses and in infants with and without lung disease. CCSP- and CCSP mRNA-containing epithelial cells also formed dusters around neuroepithelial bodies (NEBs), especially at airway branch points, suggesting that NEBs and Clara cells might interact during development and during pulmonary regeneration. Because of evidence of overlapping of some but not all cells expressing CCSP, SP-A, and pro-SP-B during lung development, a common cell lineage is proposed, with subsequent divergence of phenotypes.

Biochemical, clinical, and morphologic studies on lungs of infants with bronchopulmonary dysplasia.

We correlated clinical, biochemical, and morphologic findings in the lungs of 48 infants dying of either bronchopulmonary dysplasia (BPD) or hyaline membrane disease (HMD) to obtain a better idea of the disease process. The infants ranged from 24 weeks of gestation to 1 1/2 postnatal years. The lungs of BPD and HMD infants had higher contents of DNA, alkalisoluble protein, hydroxyproline, and desmosine, as well as increased concentrations of DNA, hydroxyproline, and desmosine when compared with the lungs of 72 control infants. BPD was classified histologically into 4 groups: Group I was a phase of acute lung injury, Group II the proliferative phase; Group III the phase of early repair, and Group IV the phase of late repair. We saw a significant increase in hydroxyproline concentration in Groups II and III. The ratio of type I/III collagen decreased in BPD Groups II to IV. Desmosine was significantly higher only in Group III than in controls. When the pathological classification was related to biochemical and clinical features of BPD, the classification showed dependence on the number of days the infant survived postnatally and not on the gestational age of the infant. The number of days on assisted ventilation was a slightly better predictor of the disease classification than days on > 60% oxygen. A statistical model correctly predicted the pathologic classification 83% of the time.

Expression of thyroid transcription factor-1(TTF-1) in fetal and neonatal human lung.

We assessed the immunohistochemical localization of thyroid transcription factor-1 (TTF-1) in the lungs of 24 human fetuses (11-23 weeks), three infants without pulmonary pathology (36-42 weeks), and 24 infants (2 days-6.5 months) with hyaline membrane disease (HMD) or bronchopulmonary dysplasia (BPD). TTF-1 was detected in fetal lung epithelial cell nuclei by 11 weeks' gestation. Budding tips of terminal airways had prominently labeled nuclei. By 17 weeks, labeling was present in scattered nonciliated columnar and cuboidal cells. Throughout gestation, TTF-1 nuclear staining was prominent in airways abutting pleural, peribronchial, or perivascular connective tissue, being less prominent in centers of lobules. By 23 weeks, many cells in cuboidal but not columnar cell-lined airways had labeled nuclei. At term, TTF-1 was detected primarily in Type II epithelial cells. In HMD with alveolar hemorrhage, edema, or airway collapse, little or no TTF-1 was present except in open terminal airways. In BDP lungs, TTF-1 was absent in areas of alveolar collapse or infection, being present in regenerating open airways. The temporal-spatial distribution of TTF-1, in general, follows patterns of distribution of surfactant protein-B in developing and pathological lungs, consistent with its role in the regulation of epithelial cell gene expression in the lung.

Limited fat digestion in infants with bronchopulmonary dysplasia.

In 10 hyaline membrane disease patients with development of bronchopulmonary dysplasia, 16 hyaline membrane disease patients without development of bronchopulmonary dysplasia, and 12 very-low-birthweight infants without major medical problems, we measured the lipase and trypsin activity as well as the bile acids concentrations in preprandially aspirated duodenal juice. In addition, fat and nitrogen balances were performed during the 5th and 6th weeks of postnatal life. The mean duodenal lipase activity in the patients with bronchopulmonary dysplasia was significantly lower than those of the patients without bronchopulmonary dysplasia (4.41 +/- 3.0 versus 9.95 +/- 3.0 U/ml, p < 0.05) and of the controls (19.94 +/- 6.8 U/ml). The mean total bile acid concentration was below the critical micellar concentration of 4 mmol/L only in the patients with bronchopulmonary dysplasia. The fecal fat excretion rate in the patients with bronchopulmonary dysplasia was significantly higher than in the patients without bronchopulmonary dysplasia (21.4 +/- 4.6% versus 11.3 +/- 3.4% of intake, p < 0.01) as well as that of the controls (7.9 +/- 2.8% of intake). The serum urea concentrations were similar in the patients without bronchopulmonary dysplasia and in the controls (1.97 +/- 0.6 and 1.89 +/- 0.4 mmol/L, respectively) but significantly higher in the patients with bronchopulmonary dysplasia (2.54 +/- 0.5 mmol/L). The lowest weight gain was found in the patients with bronchopulmonary dysplasia (8.2 +/- 4.7 g/kg/day). It was significantly lower than one of the patients without bronchopulmonary dysplasia or the controls (13.5 +/- 4.0 and 16.2 +/- 3.7 g/kg/day, respectively). The data indicate that patients who develop bronchopulmonary dysplasia have a limited fat absorption, which may help to explain the inadequate weight gain.

Immunolocalization of transforming growth factor-alpha, epidermal growth factor (EGF), and EGF-receptor in normal and injured developing human lung.

The family of growth factors that includes epidermal growth factor (EGF) and transforming growth factor-alpha (TGF-alpha) are thought to play a role in the regulation of fetal lung development and epithelial repair after injury. To further elucidate the potential role of these growth factors and their receptor in normal human lung development and in response to injury, their distribution was determined by immunohistochemistry in normal fetal lung, as well as both normal and injured postnatal human lung. We studied 14 specimens of human lung tissue: from three fetuses, four normal infants, two preterm infants with hyaline membrane disease, and five infants with late bronchopulmonary dysplasia (BPD). EGF, TGF-alpha, and EGF receptor (EGF-R) colocalized in airway epithelium in normal fetal and in postnatal human lung. They were also colocalized in scattered alveolar epithelial cells in postnatal lung. Large numbers of alveolar macrophages immunostained for EGF, TGF-alpha, and EGF-R in lungs with late stages of BPD. The colocalization of these growth factors suggests parallel expression of EGF family members. Moreover, the colocalization of these growth factors with their receptor in developing lung suggests that they may act through an autocrine mechanism. The prominent expression of these growth factors in alveolar macrophages in BPD suggests they may be involved with the pathogenesis of this disease.

Pathways of fibrin turnover in lavage of premature baboons with hyperoxic lung injury.

Lung injury induced by 100% O2 over 6 days is characterized by markedly less alveolar fibrin and rare hyaline membranes in premature versus adult baboons. To determine the mechanism(s) underlying alveolar fibrin deposition in the evolution of hyaline membrane disease (HMD) through diffuse alveolar damage (DAD) and bronchopulmonary dysplasia (BPD), we measured procoagulant and fibrinolytic activities in lung lavage of premature baboons with HMD, those treated with 100% O2 for 6 days (DAD) or for 7 days followed by 14 days 80% O2 (BPD). Lavage procoagulant activity, mainly due to tissue factor associated with Factor VII, was increased by hyperoxia. Plasminogen-dependent fibrinolytic activity, due to both tissue plasminogen activator and urokinase, was stable or increased after hyperoxia. Plasminogen activator inhibitor 1 (PAI-1) was detectable in lavage of animals with HMD but not those with evolving DAD or BPD. Antiplasmin activity was stable or decreased. Although plasminogen was undetectable in lavage, D-dimer was increased in lavage of the groups exposed to hyperoxia versus HMD. The defect in plasminogen activator activity in lavage fluids of adult baboons with DAD induced by O2 does not occur in premature baboons with HMD, evolving DAD, or BPD. Expression of fibrinolytic activity in the lower respiratory tract of premature baboons is dependent on local access to plasminogen, which is present in relatively low concentrations in plasma of these animals.

Pulmonary toxicity of deferoxamine in iron-poisoned mice.

Previously we have shown that a group of patients treated for iron overdose with prolonged deferoxamine (DFO) infusion died of adult respiratory distress syndrome (ARDS). We now describe a model to investigate the mechanism of this pulmonary toxicity. Mice treated with 1 oral dose of iron (Fe) and then multiple injections of DFO, or with the chelated product ferrioxamine alone, did not develop lung lesions, even at doses which induced mortality. To potentiate any possible free radical reaction, other groups of mice were treated similarly while exposed to 75-80% O2 over a 4-day period. Ten of 12 mice receiving 0.75 mg Fe and then DFO (10 mg, 4 times/day for 4 days) with hyperoxia died suddenly. At autopsy the lungs were dark red and solid; sections showed hyaline membranes and alveolar exudates of edema, fibrin, and PMN. Electron microscopy showed massive destruction of the alveolar epithelium; using cerium chloride, a free radical reaction product was demonstrated at the alveolar surface. Lung lavage fluid contained 10-12 x normal levels of protein when the Fe-DFO-O2 group was compared to air or O2 controls. Mice receiving DFO or Fe, plus O2, showed only slight injury and a small increase in alveolar protein. The results indicate that Fe plus DFO generates free radicals in the lung, a reaction potentiated by hyperoxia to produce an ARDS-like picture. This suggests that the pulmonary toxicity of DFO in iron-poisoned patients is due to its prooxidant activity resulting in free radical destruction of the airblood barrier.

Lactoferrin and lysozyme deficiency in airway secretions: association with the development of bronchopulmonary dysplasia.

To test whether the presence of airway inflammatory markers differentiated babies with hyaline membrane disease (HMD) who recovered (n = 18) from those in whom bronchopulmonary dysplasia (BPD) developed (n = 18), tracheal aspirate samples from 36 newborn infants with HMD who underwent intubation were collected during days 1 to 28 of life and analyzed for the mucosal antimicrobial proteins lactoferrin and lysozyme. For babies with HMD in whom BPD developed, lactoferrin concentrations were decreased during the first 4 days of life (7 +/- 3, 14 +/- 3, 18 +/- 3, and 18 +/- 3 micrograms/ml, respectively) in comparison with those in babies with HMD who recovered (23 +/- 8, 29 +/- 6, 41 +/- 9, and 81 +/- 19 micrograms/ml); group differences reached statistical significance on days 3 and 4 (p less than 0.05). Lysozyme levels in the secretions of babies with BPD were also lower on day 3 (31 +/- 5 micrograms/ml) than in those of babies who recovered (54 +/- 7.5 micrograms/ml). For babies with BPD whose endotracheal tube remained in place beyond day 4, lysozyme levels on days 5 to 12 were significantly lower for those classified as having severe BPD than for those with mild to moderate BPD. Because lysozyme and lactoferrin are products of serous cells found in submucous glands, it seems possible that the relative immaturity of submucous glands may influence the development of BPD.

Alterations in surfactant protein gene expression associated with premature birth and exposure to hyperoxia.

Steady-state levels of mRNAs for the three surfactant-associated proteins, SP-A, SP-B, and SP-C, were measured in a primate model of premature birth and survival. These values were determined by Northern and quantitative slot blot analyses of total lung RNA during both in utero and extrauterine development of the fetus as well as in response to hyperoxic exposure. The composition and surface properties of surfactant were also analyzed to determine the effect of differential expression of the surfactant proteins on the overall composition and function of surfactant. The data clearly demonstrate that the regulation of surfactant mRNA levels in the premature fetus is under complex physiological control. Interruption of in utero development by premature birth results in increased levels of all three surfactant mRNAs, presumably in response to precocious initiation of air breathing. Within the first 24 h after parturition both SP-B and SP-C mRNA levels are increased beyond the levels found in the full-term fetal controls. Expression of mRNA for these genes peaks on day 2 and thereafter drops to levels below that found on day 1. However, response of the SP-A gene to premature birth is slow and transcripts from this gene lag considerably behind values found in the full-term fetus. Furthermore, exposure of the premature fetus to hyperoxia results in an increase in the steady-state levels of SP-B and SP-C mRNA without significant changes in SP-A. Defects in the ability of the SP-A gene to respond to extrauterine exposure and hyperoxia may be contributing to development of bronchopulmonary dysplasia, a common clinical complication of premature birth in humans.

The disposition of alfentanil in neonates with respiratory distress.

The disposition of continuous infusion alfentanil was evaluated in 13 mechanically ventilated neonates (gestational age 37.6 +/- 2.4 wks) with hyaline membrane disease (n = 7) or persistent pulmonary hypertension of the newborn (n = 6). Alfentanil was administered as a loading dose 8 micrograms/kg, followed by a variable-rate continuous infusion (maximum 10 micrograms/kg/hr; minimum 2.5 micrograms/kg/hr) for 27 hours. Serial plasma samples were obtained for pharmacokinetic analysis. Noncompartmental pharmacokinetic analysis of the data revealed the following estimates (mean +/- SD): total-body clearance 3.24 +/- 2.23 ml/kg/minute, volume of distribution 0.54 +/- 0.21 L/kg, and elimination half-life 4.14 +/- 2.58 hours. A significant effect of alfentanil plasma concentration on total-body clearance was found (r = -0.75; p = 0.02), suggesting nonlinear pharmacokinetics. No correlation was seen between total-body clearance and alfentanil dose (r = -0.37; p = 0.32). The results suggest that a larger dose-proportionality study is required to determine the linearity or nonlinearity of alfentanil pharmacokinetics in neonates.

Surfactant-associated glycoproteins accumulate in alveolar cells and secretions during reparative stage of hyaline membrane disease.

Surfactant-associated (SA) glycoproteins are lung-specific proteins produced in the human lung by alveolar type II cells and Clara cells. The distribution of these proteins was studied immunohistochemically in lung tissue obtained postmortem from 12 stillborn fetuses and 49 infants with hyaline membrane disease (HMD). By 21 weeks of gestation, SA glycoproteins were detected in the fetal alveolar epithelium and within Clara cells. The staining increased in intensity and extent with advancing gestational age. Infants with HMD who survived less than 48 hours did not generally exhibit stainable material either within type II cells or secretions, but staining was often noted in Clara cells as well as focally beneath hyaline membranes. In infants surviving more than 48 hours, intense staining of hyaline membranes, alveolar secretions, proliferating alveolar type II cells, and Clara cells was evident. Immunoreactivity was intense in hypertrophic type II cells that formed a continuous alveolar epithelial lining in lungs with bronchopulmonary dysplasia. Included in the population of infants with HMD were 15 infants with pulmonary hypoplasia. The lungs of these infants showed minimal staining for SA glycoproteins regardless of postnatal survival time. The results provide an immunomorphologic basis for defining normal and abnormal lung maturation. They also indicate that enhanced SA glycoprotein production is a sustained response of regenerating and hypertrophic type II cells in premature infants.

Increased airway leukotriene levels in infants with severe bronchopulmonary dysplasia.

The sulphidopeptide leukotrienes (C4, D4, and E4) are potent airway constrictors that have been detected in the airways of infants with pulmonary hypertension and viral infections. The present study was undertaken to test the hypothesis that leukotrienes in tracheal lavage fluid are elevated in bronchopulmonary dysplasia. Twenty-six intubated infants (10 with bronchopulmonary dysplasia, 9 with hyaline membrane disease, and 7 normal controls) had tracheal lavage leukotriene levels determined by radioimmunoassay. Lavage fluid cell counts (alveolar macrophages) and leukotriene levels were significantly increased in infants with severe bronchopulmonary dysplasia. The increased concentration of leukotrienes seen in the infants with bronchopulmonary dysplasia would suggest a possible role for these compounds in the pathophysiology of this disease.

Immunocytochemical localization of epidermal growth factor in the developing human respiratory system and in acute and chronic lung disease in the neonate.

Cells staining for immunoreactive human epidermal growth factor were sought in the lungs and tracheas of human fetuses from 8 to 24 weeks of gestation. Lungs of liveborn infants from 25 to 40 weeks of gestation (stillborn to 7 months postnatal life), both with and without lung pathology, were also studied. In the early fetal trachea (12 to 15 weeks), many nonciliated cells immunostained for immunoreactive human epidermal growth factor in the lining epithelium. By 16 weeks of gestation this widespread staining was replaced by stained nonciliated single cells or small clusters of cells which were identifiable until 24 weeks. In the few tracheas which were available from liveborn infants who died without evidence of lung disease, stained cells were seldom identified in the lining epithelium after 24 weeks of gestation. In contrast, from 18 weeks until term, tracheal submucosal glands contained scattered cells which immunostained for immunoreactive human epidermal growth factor but which did not appear to be classical mucous cells. Beginning at 20 weeks of gestation, positively staining cells were found occasionally in bronchial lining epithelium, but more often in bronchial submucosal glands. Immunostained cells were never identified in bronchiolar epithelium in normal fetal or newborn lungs. In liveborn infants from 24 weeks onward who developed lung disease, many tracheas were severely damaged. In the presence of extensive denudation of the mucosa or the development of squamous metaplasia, immunostained cells were rarely seen in the lining epithelium. However, even under these conditions stained glandular cells could usually be identified. Stained cells were also present in the necks of those tracheal glands from which new epithelial lining cells appeared to be migrating onto denuded surfaces. Immunostained cells in the bronchial lining epithelium of infants with chronic lung disease were infrequent, just as they were in the fetus, but bronchial submucosal glands contained positively stained cells similar to those in tracheal glands. The appearance and distribution of immunostained cells were similar in the tracheal and bronchial submucosal glands in both normal subjects and those with all stages of lung disease. In contrast to the bronchioles of fetuses and infants without lung pathology, the bronchiolar epithelium of infants with chronic lung disease contained immunostained cells. Immunostained cells were found in areas of migrating dysplastic cells in relining conducting airways.(ABSTRACT TRUNCATED AT 400 WORDS)