Comparison of secretory component for immunoglobulin A with albumin as reference proteins in tracheal aspirate from preterm infants

Cardiopulmonary Bypass in Premature and Low Birth Weight Neonates - Implications for Postoperative Care From a Neonatologist/Intensivist Perspective

Prematurity and low weight remain significant risk factors for mortality after neonatal cardiac surgery despite steady gains in survival. Newer and lower weight thresholds for operability are constantly generated as surgeons gather proficiency, technical mastery, and experience in performing complex procedures on extremely small infants. Relationship between birth weight and survival after cardiac surgery is nonlinear with 2 kg being an inflection point below which marked decline in survival occurs. If strides toward improved survival in this weight category are to be made, understanding the inherent vulnerabilities of the premature and low birth weight infant is important in addition to acknowledging the vulnerabilities of the system in which care is delivered.

Low level of tracheal cellular fibronectin in extremely premature infants with funisitis: relationship with respiratory distress 1 month after birth

BACKGROUND

Funisitis reflects the fetal systemic inflammatory response in premature infants. Macrophages and neutrophils have been identified as key elements in the inflammatory process of the lungs, and secrete proteases that cause the destruction of the extracellular matrix (ECM). Fibronectin (FN) is the major constituent of the pulmonary ECM and exists in multiple isoforms arising from alternative RNA splicing. Extra domain A (EDA) is the major alternatively spliced segment, and the expression of EDA containing FN (EDA + FN) in the lungs is associated with distal pulmonary cell proliferation during alveolar formation.

OBJECTIVE

To study the relationship between the presence of funisitis and EDA + FN levels in the tracheal aspirate fluid (TAF) of infants of less than 28 weeks' gestation.

METHODS

The subjects included in this study were 26 extremely premature infants of <28 weeks' gestation at <24 hr of age, from whom the TAF was collected. These preterm infants were divided into two groups according to placental histology. The funisitis (+) group (n = 9) was compared with the funisitis (-) group (n = 17). The TAF supernatants were analyzed for IL-1β, IL-6, IL-8, neutrophil elastase, and EDA + FN using enzyme-linked immunosorbent assay (ELISA).

RESULTS

There were no significant differences in gestational age or birthweight between these groups. The funisitis (+) group had a significantly higher ventilator setting (inspired O(2)  × mean airway pressure) at Day 28 than the funisitis (-) group. In the TAF, the concentrations of IL-1β were significantly higher in the funisitis (+) group than in the funisitis (-) group, as were the concentrations of neutrophil elastase. The concentrations of EDA + FN were significantly lower in the funisitis (+) group than in the funisitis (-) group.

CONCLUSIONS

Decreased EDA + FN in TAF might be one of the risk factors leading to respiratory distress in extremely premature infants with funisitis.

Neonatal cardiac care, a perspective

Every year in the United States approximately 40,000 infants are born with congenital heart disease. Several of these infants require corrective or palliative surgery in the neonatal period. Mortality rates after cardiac surgery are highest amongst neonates, particularly those born prematurely. There are several reasons for the increased surgical mortality risk in neonates. This review outlines these risks, with particular emphasis on the relative immaturity of the organ systems in the term and preterm neonate.

Airway angiopoietin-2 in ventilated very preterm infants: association with prenatal factors and neonatal outcome

OBJECTIVE

Pulmonary angiogenesis is a prerequisite for lung development. Angiopoietin-2 (Ang2) destabilizes endothelial cells through its endothelial receptor TIE-2, enabling vascular sprouting. Ang1 stabilizes new blood vessels. Soluble TIE-2 (sTIE-2) modulates these effects. We hypothesized that histological funisitis is associated with alterations of Ang2 in airways and of the systemic angiopoietin-TIE-2 homeostasis in very low birth weight (VLBW) infants, contributing to pulmonary morbidity and mortality.

METHODS

We measured Ang2 in tracheobronchial aspirate fluid (TAF) of 42 VLBW <30 weeks of gestation from day 1 through 15 and Ang1, Ang2, and sTIE-2 in umbilical cord serum of 28 infants by enzyme-linked immunosorbent assay. Histological examination distinguished three groups: funisitis, chorioamnionitis, and controls.

RESULTS

Funisitis was associated with lower Ang2 values in TAF but not with changes of Ang1, Ang2, and sTIE-2 in umbilical cord serum. Infants who developed bronchopulmonary dysplasia (BPD) or died had a persistently decreased ratio of previously measured Ang1 to Ang2 in TAF on days 1-5 and increased cord serum concentrations of sTIE-2. Moderate BPD/death was associated with an increase of Ang2 in TAF on day 10 and decreased Ang1/Ang2 ratio from day 3-15. Small for gestational age (SGA) infants had increased Ang2 in TAF on day 1-7 and a lower Ang1/Ang2 ratio on days 5-7.

CONCLUSIONS

The predominance of Ang2 in airway fluid of infants with BPD/death and SGA infants suggests a link between disrupted placental and fetal pulmonary angiogenesis. Histological funisitis with reduced Ang2 in TAF was of minor relevance for outcome in our cohort.

Quantification of amikacin in bronchial epithelial lining fluid in neonates

Amikacin efficacy is based on peak concentrations and the possibility of reaching therapeutic levels at the infection site. This study aimed to describe amikacin concentrations in the epithelial lining fluid (ELF) through bronchoalveolar lavage (BAL) in newborns. BAL fluid was collected in ventilated neonates treated with intravenous (i.v.) amikacin. Clinical characteristics, amikacin therapeutic drug monitoring serum concentrations, and the concentrations of urea in plasma were extracted from the individual patient files. Amikacin and urea BAL fluid concentrations were determined using liquid chromatography with pulsed electrochemical detection (LC-PED) and capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C(4)D), respectively. ELF amikacin concentrations were converted from BAL fluid concentrations through quantification of dilution (urea in plasma/urea in BAL fluid) during the BAL procedure. Twenty-two observations in 17 neonates (postmenstrual age, 31.9 [range, 25.1 to 41] weeks; postnatal age, 3.5 [range, 2 to 37] days) were collected. Median trough and peak amikacin serum concentrations were 2.1 (range, 1 to 7.1) mg/liter and 39.1 (range, 24.1 to 73.2) mg/liter; the median urea plasma concentration was 30 (8 to 90) mg/dl. The median amikacin concentration in ELF was 6.5 mg/liter, the minimum measured concentration was 1.5 mg/liter, and the maximum (peak) was 23 mg/liter. The highest measured ELF concentration was reached between 6 and 14.5 h after i.v. amikacin administration, and an estimated terminal elimination half-life was 8 to 10 h. The median and highest (peak) ELF amikacin concentrations observed in our study population were, respectively, 6.5 and 23 mg/liter. Despite the frequent use of amikacin in neonatal (pulmonary) infections, this is the first report of amikacin quantification in ELF in newborns.

Ureia como marcador de diluição em amostras de lavado traqueobrônquico de potros com rodococose

No estudo das infecções e dos mecanismos inflamatórios do trato respiratório posterior, a diluição desconhecida de amostras de lavados traqueobrônquicos leva a um grave problema na interpretação das concentrações de várias substâncias. Foi investigada a amplitude da diluição em uma situação clínica verdadeira, com o objetivo de determinar a validez do uso da dosagem da ureia em lavados traqueobrônquicos para correção da diluição. As amostras do estudo consistiram em lavados traqueobrônquicos obtidos de sete potros com infecção por Rhodococcus equi. Foi realizada a contagem celular total e diferencial e comprado com o quadro clínico e a recuperação bacteriana de todas as amostras. Os fatores de diluição dos lavados variaram entre 14,3 e 130 (média 59,7). O uso da ureia como marcador de diluição melhorou a exatidão na determinação da concentração total de células nos lavados. Estes resultados sugerem que a prática de mensurar substâncias em lavado traqueobrônquico sem correção da diluição possa induzir a falsas conclusões.

Soluble receptor for advanced glycation end products (sRAGE) in tracheobronchial aspirate fluid and cord blood of very low birth weight infants with chorioamnionitis and funisitis

BACKGROUND

A systemic fetal inflammatory response, reflected by histological funisitis is associated with pulmonary morbidity and increased mortality after premature birth. The receptor for advanced glycation end products (RAGE) is a membrane-bound multiligand receptor with a key role in inflammation. Soluble RAGE (sRAGE) is created by alternative mRNA splicing or shedding of the receptor's extracellular domain and can inhibit RAGE-activation.

AIMS

To assess the association of funisitis with airway and systemic concentrations of sRAGE in very premature infants.

METHODS

Forty-two ventilated infants (gestational age: 27.4 +/- 1.8weeks, birth weight: 1017 +/- 229 g [mean +/- SD]) were studied. sRAGE concentrations were measured in tracheobronchial aspirate fluid (TAF) on days of life 1, 3, 5, 7 and 10 and in umbilical cord serum of 28 infants by ELISA. The secretory component for IgA (SC) served as reference protein in TAF. Placental tissue, membranes and umbilical cords were examined microscopically to distinguish three groups: chorioamnionitis (n=9), funisitis (n=17) and controls (n=16).

RESULTS

The funisitis group had lower sRAGE concentrations than both other groups in cord blood serum (median: 0.52 ng/ml [25th-75th centile: 0.32-0.91]; control, 1.72 [1.02-2.69]; chorioamnionitis, 1.44 [0.92-1.63], p<0.01) and TAF on day 1 (290 ng/ngSC [140-400]; control, 2750 [1470-28920]; chorioamnionitis, 2150 [1220-7140], p<0.01). sRAGE in TAF remained lower in the funisitis than in the chorioamnionitis group on days 3 and 10, p<0.01 respectively.

CONCLUSIONS

Decreased sRAGE in airways and circulation after funisitis may contribute to an imbalance between pro- and anti-inflammatory factors priming very premature infants for pulmonary injury and increasing the risk of adverse outcome.

Expression of water and ion transporters in tracheal aspirates from neonates with respiratory distress

AIM

The aim of the study was to determine whether neonatal respiratory distress is related to changes in water and ion transporter expression in lung epithelium.

METHODS

The study included 32 neonates on mechanical ventilation: 6 patients with normal lung X-rays (control group), eight with respiratory distress syndrome (RDS), eight with transient tachypnea of the newborn (TTN), 10 with abnormal lung X-rays (mixed group). The protein abundance of water channel AQP5, epithelial sodium channel (ENaC; alpha-, beta- and gamma-ENaC) and Na(+), K(+)-ATPase alpha1 were examined in tracheal aspirates using semiquantitative immunoblotting.

RESULTS

beta-ENaC level was significantly lower in RDS group compared with infants with TTN and infants in the control group. AQP5 expression was significantly higher in TTN compared with the infants with RDS and all other infants with abnormal lung X-rays.

CONCLUSION

Neonatal respiratory distress is associated with changes in beta-ENaC and AQP5 expression. The lower beta-ENaC expression may be one of the factors that predispose to the development of RDS. The higher AQP5 expression may provide the possibility for reabsorption of postnatal lung liquid, which contributes to quick recovery of infants with TTN.

Airway concentrations of angiopoietin-1 and endostatin in ventilated extremely premature infants are decreased after funisitis and unbalanced with bronchopulmonary dysplasia/death

A systemic inflammatory response of the fetus, reflected by histologic funisitis, is a risk factor for bronchopulmonary dysplasia (BPD). Impaired pulmonary angiogenesis accompanied by simplification and rarification of alveoli is a histologic hallmark of BPD. Angiopoietin-1 mediates vascular development, maturation, and stabilization. Endostatin mainly acts as an angiostatic factor. We hypothesized that funisitis was associated with changes of endostatin and angiopoietin-1 concentrations in the airways and that an imbalance between the factors might be associated with BPD or death. We measured concentrations of angiopoietin-1 and endostatin by enzyme-linked immunosorbent assay in tracheobronchial aspirate fluid samples of 42 ventilated preterm infants during postnatal days 1 through 15. The secretory component for IgA served as reference protein. A standardized histologic examination was used to distinguish three groups: chorioamnionitis, funisitis, and controls without inflammation. Concentrations of the mediators steadily decreased. Funisitis was associated with lower concentrations of both proteins, which might impair their physiologic activities in pulmonary angiogenesis. An increase of the ratio angiopoietin-1/endostatin until day 7 of life indicated a shift of the mediators potentially favoring angiogenesis. However, infants, who developed BPD or died, had a decreased ratio on days 1, 3, and 15, suggesting an imbalance toward inhibition of pulmonary angiogenesis.

Angiopoietin 2 concentrations in infants developing bronchopulmonary dysplasia: attenuation by dexamethasone

OBJECTIVES

To study the association between angiopoietin 2 (Ang2) concentrations in tracheal aspirates (TAs) and adverse outcome (bronchopulmonary dysplasia (BPD)/death) in ventilated premature infants (VPIs) and modulation of Ang2 concentrations with dexamethasone (Dex) use.

STUDY DESIGN

Serial TA samples were collected on days 1, 3, 5 and 7, and Ang2 concentrations were measured. Ang2 TA concentrations were compared prior to and after 48 to 72 h of using Dex.

RESULT

A total of 151 TA samples were collected from 60 VPIs. BPD was defined as the oxygen requirement at 36 weeks postmenstrual age (PMA). Twelve infants (mean+/-s.d.) (gestational age (GA) 26.5+/-2.1 weeks, birth weight (BW) 913+/-230 g) had no BPD, 32 infants (GA 25.8+/-1.4 weeks, BW 768+/-157 g) developed BPD and 16 infants (GA 24.5+/-1.1 weeks, BW 710+/-143 g) died before 36 weeks PMA. Ang2 concentrations were significantly lower in infants with no BPD (median, 25th and 75th percentile) (157, 16 and 218 pg mg(-1)) compared with those who developed BPD (234, 138 and 338 pg mg(-1), P=0.03) or BPD and/or death (234, 157 and 347 pg mg(-1), P=0.017), in the first week of life. Twenty-six VPIs (BW 719+/-136 g, GA 25.1+/-1.3 weeks) received 27 courses of Dex. Ang2 concentrations before starting Dex were 202, 137 and 278 pg mg(-1) and significantly decreased to 144, 0 and 224 pg mg(-1) after therapy (P=0.007).

CONCLUSIONS

Higher Ang2 concentrations in TAs are associated with the development of BPD or death in VPIs. Dex use suppressed Ang2 concentrations.

Pepsin, a marker of gastric contents, is increased in tracheal aspirates from preterm infants who develop bronchopulmonary dysplasia

OBJECTIVE

The objective of this study was to study the association between pepsin in tracheal aspirate samples and the development of bronchopulmonary dysplasia in preterm infants.

METHODS

Serial tracheal aspirate samples were collected during the first 28 days from mechanically ventilated preterm neonates. Bronchopulmonary dysplasia was defined as the need for supplemental oxygen at 36 weeks' postmenstrual age. An enzymatic assay with a fluorescent substrate was used to detect pepsin. Total protein was measured by the Bradford assay to correct for the dilution during lavage. Immunohistochemistry using antibody against human pepsinogen was performed in 10 lung tissue samples from preterm infants.

RESULTS

A total of 256 tracheal aspirate samples were collected from 59 preterm neonates. Pepsin was detected in 234 (91.4%) of 256 of the tracheal aspirate samples. Twelve infants had no bronchopulmonary dysplasia, 31 infants developed bronchopulmonary dysplasia, and 16 infants died before 36 weeks' postmenstrual age. The mean pepsin concentration was significantly lower in infants with no bronchopulmonary dysplasia compared with those who developed bronchopulmonary dysplasia or developed bronchopulmonary dysplasia/died before 36 weeks' postmenstrual age. Moreover, the mean pepsin level was significantly higher in infants with severe bronchopulmonary dysplasia compared with moderate bronchopulmonary dysplasia. The mean pepsin level in tracheal aspirate samples from the first 7 days was also lower in infants with no bronchopulmonary dysplasia compared with those who developed bronchopulmonary dysplasia or developed bronchopulmonary dysplasia/died before 36 weeks' postmenstrual age. Pepsinogen was not localized in the lung tissues by immunohistochemistry.

CONCLUSION

The concentration of pepsin was increased in the tracheal aspirate of preterm infants who developed bronchopulmonary dysplasia or died before 36 weeks' postmenstrual age. Recovery of pepsin in tracheal aspirate samples is secondary to gastric aspiration, not by hematogenous spread or local synthesis in the lungs. Chronic aspiration of gastric contents may contribute in the pathogenesis of bronchopulmonary dysplasia.

Systemic fetal inflammation and reduced concentrations of macrophage migration inhibitory factor in tracheobronchial aspirate fluid of extremely premature infants

OBJECTIVE

Macrophage migration inhibitory factor is a proinflammatory mediator of innate immunity, enhances cell growth, and plays a role in preterm delivery. We speculated that funisitis, reflecting fetal systemic inflammation, would be associated with higher concentrations of macrophage migration inhibitory factor in airways of extremely premature infants.

STUDY DESIGN

We measured macrophage migration inhibitory factor by enzyme linked immunosorbent assay in tracheobronchial aspirate fluid of 35 ventilated infants less than 30 weeks' gestational age, throughout the first week of life. Three groups were distinguished histologically: chorioamnionitis, funisitis, and control.

RESULTS

Unexpectedly, funisitis was associated with significantly decreased macrophage migration inhibitory factor in tracheobronchial aspirate fluid on day 1 (P < .01) and levels remained lower than in the chorioamnionitis group thereafter. For the 35 patients in total, macrophage migration inhibitory factor steadily declined.

CONCLUSION

Decreased macrophage migration inhibitory factor concentrations in airways of extremely premature infants with systemic fetal inflammation early in life might predispose them to pulmonary infection and interfere with maturation of the lung, contributing to adverse pulmonary outcome.

High concentrations of plasminogen activator inhibitor-1 in lungs of preterm infants with respiratory distress syndrome

BACKGROUND

Among preterm infants, respiratory distress syndrome (RDS) is characterized by the presence of intraalveolar fibrin deposition. Fibrin monomers inhibit surfactant function effectively. However, little is known about potential disturbances of intraalveolar fibrinolysis in RDS. We studied levels of major plasminogen activator inhibitor-1 (PAI-1), tissue-type plasminogen activator (tPA), and urokinase-type plasminogen activator (uPA) in lungs of preterm infants with RDS.

METHODS

The antigen levels of PAI-1, tPA, and uPA were measured in 262 samples of tracheal aspirate fluid collected from 37 intubated preterm infants during the first 2 postnatal weeks. To examine the expression of PAI-1, tPA, and uPA in lung tissue, immunohistochemical analyses were performed on autopsy specimens from 7 preterm infants with RDS and 6 newborn infants without pulmonary pathologic conditions.

RESULTS

For infants with an immature surfactant profile, as indicated by lecithin/sphingomyelin ratios in tracheal aspirate fluid of < 10, PAI-1 levels and ratios of PAI-1 to uPA and tPA were significantly higher during postnatal days 1 to 2, compared with infants with lecithin/sphingomyelin ratios of > or = 10. Moreover, infants who subsequently developed bronchopulmonary dysplasia (BPD) (n = 15) had higher PAI-1 levels on days 3 to 4 and days 7 to 8 than did those who survived without BPD. For preterm infants with RDS, immunohistochemical analyses demonstrated increased expression of PAI-1, tPA, and uPA predominantly in alveolar epithelium.

CONCLUSIONS

High concentrations of PAI-1 and an increased ratio of PAI-1 to uPA, with a concurrently less-increased ratio of PAI-1 to tPA, are associated with the severity of RDS among preterm infants during the first postnatal days. Pulmonary inhibition of fibrinolysis is a pathophysiologic feature of RDS and may play a role in the development of BPD.

Fetal alcohol exposure impairs alveolar macrophage function via decreased glutathione availability

Immature function of the alveolar macrophage increases the risk of pulmonary infections in premature newborns. In utero alcohol increases fetal systemic oxidative stress. Because the premature lung is deficient in glutathione (GSH), we hypothesized that chronic in utero alcohol (ethanol) exposure exacerbates the oxidative stress within the developing lung, thereby impairing alveolar macrophage function. Additionally, we evaluated the effects of in vivo and in vitro GSH availability on ethanol-exposed macrophage function. Using a guinea pig model of chronic in utero ethanol exposure, fetal epithelial lining fluid (ELF) and alveolar macrophage GSH were decreased with increased markers of oxidative stress. Ethanol-exposed macrophage exhibited impaired phagocytosis and increased apoptosis compared with gestational control. When the GSH precursor S-adenosyl-methionine (SAM) was added to the maternal drinking water containing ethanol, fetal ELF and macrophage GSH were maintained and ELF oxidative stress diminished. In vivo maternal SAM therapy maintained macrophage phagocytosis and decreased apoptosis. In vitro GSH supplements also improved phagocytosis and viability in both premature and ethanol-exposed macrophage. This suggested that in utero ethanol impaired premature macrophage function and viability via decreased GSH availability. Furthermore, GSH supplementation during and after ethanol exposure improved fetal macrophage function and viability. These results add a new dimension to the detrimental effects of fetal alcohol exposure on the developing alveolar macrophage, raising the possibility of GSH therapy to augment premature alveolar macrophage function.

Elevated platelet-derived growth factor-BB concentrations in premature neonates who develop chronic lung disease

BACKGROUND

Chronic lung disease (CLD) in the preterm newborn is associated with inflammation and fibrosis. Platelet-derived growth factor-BB (PDGF-BB), a potent chemotactic growth factor, may mediate the fibrotic component of CLD. The objectives of this study were to determine if tracheal aspirate (TA) concentrations of PDGF-BB increase the first 2 weeks of life in premature neonates undergoing mechanical ventilation for respiratory distress syndrome (RDS), its relationship to the development of CLD, pulmonary hemorrhage (PH) and its relationship to airway colonization with Ureaplasma urealyticum (Uu).

METHODS

Infants with a birth weight less than 1500 grams who required mechanical ventilation for RDS were enrolled into this study with parental consent. Tracheal aspirates were collected daily during clinically indicated suctioning. Uu cultures were performed on TA collected in the first week of life. TA supernatants were assayed for PDGF-BB and secretory component of IgA concentrations using ELISA techniques.

RESULTS

Fifty premature neonates were enrolled into the study. Twenty-eight infants were oxygen dependent at 28 days of life and 16 infants were oxygen dependent at 36 weeks postconceptual age. PDGF-BB concentrations peaked between 4 and 6 days of life. Maximum PDGF-BB concentrations were significantly higher in infants who developed CLD or died from respiratory failure. PH was associated with increased risk of CLD and was associated with higher PDGF-BB concentrations. There was no correlation between maximum PDGF-BB concentrations and Uu isolation from the airway.

CONCLUSIONS

PDGF-BB concentrations increase in TAs of infants who undergo mechanical ventilation for RDS during the first 2 weeks of life and maximal concentrations are greater in those infants who subsequently develop CLD. Elevation in lung PDGF-BB may play a role in the development of CLD.

Low levels of tissue inhibitors of metalloproteinases with a high matrix metalloproteinase-9/tissue inhibitor of metalloproteinase-1 ratio are present in tracheal aspirate fluids of infants who develop chronic lung disease

OBJECTIVE

The pathogenesis of chronic lung disease (CLD) involves inflammation with proteolytic damage to lung extracellular matrix. Matrix metalloproteinases (MMPs) are zinc-dependent endopeptidases that, acting in concert with their tissue inhibitors, tightly orchestrate extracellular matrix morphogenesis and repair after injury. Imbalances in their levels relative to that of their inhibitors have been implicated in diseases characterized by matrix disruption and remodeling. We investigated the possibility that imbalances in MMP-9 and MMP-2 relative to their tissue inhibitor of metalloproteinase-1 (TIMP-1) and TIMP-2, respectively, in tracheal aspirates of preterm infants may be involved in the development of CLD.

METHODS

Serial tracheal aspirates collected from birth until extubation in 49 ventilated preterm infants (24-32 weeks' gestations) were analyzed for MMP-2, MMP-9, TIMP-1, and TIMP-2. Data normalized by TA values of free secretory component of immunoglobulin A were compared for CLD (n = 22) versus no CLD (n = 27). Also, known clinical predictors of CLD (gestational age, birth weight, and sex) were assessed for both groups. Association of predictors with the outcome CLD was assessed by logistic regression.

RESULTS

Mean gestational age was lower in CLD infants, but birth weight and gender were comparable for both groups. CLD infants had significantly lower TIMP-1 level with higher MMP-9/TIMP-1 ratio during the first 2 weeks of life and low TIMP-2 and MMP-2 levels during the first 3 days of life compared with no-CLD infants. Logistic regression analysis indicated that the findings are predictive of CLD.

CONCLUSIONS

We conclude that low tracheal aspirate levels of TIMPs, with a high MMP-9/TIMP-1 ratio early in life, are associated with subsequent development of CLD.

CC chemokine concentrations increase in respiratory distress syndrome and correlate with development of bronchopulmonary dysplasia

Inflammation is one of the primary processes underlying respiratory distress syndrome (RDS) and its evolution into bronchopulmonary dysplasia (BPD). Recruitment and subsequent activation of macrophages in the lung are mediated by CC chemokines. The role of CC chemokines has not been extensively studied in the course of RDS. Serial tracheal aspirates (TA) were obtained from 56 mechanically ventilated infants with birth weights less than 1,500 g during intervals in the first 21 days of life. Tracheal aspirate concentrations of monocyte chemoattractant proteins-1,2,3 (MCP-1,2,3) and macrophage inflammatory proteins-1alpha and -1beta (MIP-1alpha, MIP-1beta) were determined by enzyme-linked immunosorbent assay (ELISA). Tracheal aspirate concentrations of MCP-1, MCP-2, MCP-3, and MIP-1beta increased during the first week of life in infants with RDS, whereas MIP-1alpha concentrations did not increase appreciably. Increased TA cytokine concentrations were associated with the development of BPD. Maximal TA concentrations of MCP-1, MCP-2, MCP-3, MIP-1alpha, and MIP-1beta were significantly higher in infants who were oxygen-dependent at 28 postnatal days compared to infant who were not. Similarly, maximal TA MCP-1, MCP-2, and MCP-3 but not MIP-1alpha and MIP-1beta concentrations were significantly higher in infants who were oxygen-dependent at 36 weeks of postconceptional age (PCA) than those who were not oxygen-dependent at 36 weeks PCA. Histologic chorioamnionitis and isolation of Ureaplasma urealyticum from the airways were associated with higher maximal TA concentrations of MIP-1alpha and MIP-1beta. Pulmonary hemorrhage was associated with increased maximal concentrations of MCP-1, MCP-2, and MCP-3. These data suggest a role for CC chemokines in the development of BPD in the newborn infant.

Albumin infusion for low serum albumin in preterm newborn infants

BACKGROUND

Intravenous albumin infusion to treat hypoalbuminaemia is used in intensive care nurseries. Hypoalbuminaemia occurs in a number of clinical situations including prematurity, the acutely unwell infant, respiratory distress syndrome (RDS), chronic lung disease (CLD), necrotising enterocolitis (NEC), intracranial haemorrhage, hydrops fetalis and oedema. Fluid overload is a potential side effect of albumin administration. Albumin is a blood product and therefore carries the potential risk of infection and adverse reactions. Albumin is also a scarce and expensive resource.

OBJECTIVES

The primary objective was to assess whether albumin infusions, in preterm neonates with low serum albumin, reduces mortality and morbidity. A secondary objective was to assess whether albumin infusion is associated with significant side effects.

SEARCH STRATEGY

Searches were made of MEDLINE from 1966 to April 2004, CINAHL from 1982 to April 2004 and the current Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library issue 1, 2004). Previous reviews (including cross references) and abstracts were also searched.

SELECTION CRITERIA

All randomised controlled trials in which individual patients were allocated to albumin infusion versus control were included. Cross-over studies were excluded. Quasi randomised trials were excluded. Participants were preterm infants who had hypoalbuminaemia. Types of interventions included albumin infusion versus placebo (e.g. crystalloid) or no treatment.

DATA COLLECTION AND ANALYSIS

The reviewers worked independently to search for trials for inclusion and to assess methodological quality. Studies were assessed using the following key criteria: blinding of randomisation, blinding of intervention, completeness of follow up and blinding of outcome measurement.

MAIN RESULTS

Only two small studies were found for inclusion in this review and only one reported clinically relevant outcomes - it found no significant differences for our primary outcome measure of death (RR 1.5 [95% confidence interval 0.3 - 7.43]) or secondary outcome measures of intraventricular haemorrhage, patent ductus arteriosus, necrotising enterocolitis, bronchopulmonary dysplasia, duration of mechanical ventilation and duration of oxygen therapy.

REVIEWERS' CONCLUSIONS

There is a lack of evidence from randomised trials to determine whether the routine use of albumin infusion, in preterm neonates with low serum albumin, reduces mortality or morbidity, and no evidence to assess whether albumin infusion is associated with significant side effects. There is a need for good quality, double-blind randomised controlled trials to assess the safety and efficacy of albumin infusions in preterm neonates with low serum albumin.

The TNF-alpha -308, MCP-1 -2518 and TGF-beta1 +915 polymorphisms are not associated with the development of chronic lung disease in very low birth weight infants

Chronic lung disease (CLD) in premature newborns is associated with increased concentrations of inflammatory cytokines in tracheal aspirates (TA). We determined if polymorphisms of cytokine genes influence the risk of developing CLD by genotyping 178 mechanically ventilated very low birth weight (VLBW) infants for the tumor necrosis factor-alpha (TNF-alpha) -308 G/A, transforming growth factor-beta(1) (TGF-beta(1)) +915 G/C and monocyte chemoattractant protein-1 (MCP-1) -2518 A/G polymorphisms. Genomic DNA was isolated from TA and genotypes determined by restriction length polymorphism. There was no effect of any of these polymorphisms on the development of CLD (29 vs 23%, P=0.371, TNF-alpha -308 AA/AG vs TNF-alpha -308 GG; 23 vs 26%, P=0.681, MCP-1 -2518 GG/AG vs MCP-1 -215-8 AA; 24 vs 24%, P=0.978, TGF-beta(1) +915 CG vs TGF-beta(1) +915 GG). TA IL-8 and MCP-1 concentrations were not different between genotype groups. Infants with the TNF-alpha -308 A allele had increased risk of IVH (RR 2.07; 95% CI 1.02-4.18, P=0.041) and infants with the TGF-beta(1) +915 C allele were at greater risk of death (32 vs 9%, P=0.016). These data suggest that these polymorphisms do not play a significant role in determining risk for CLD in preterm infants, but may play a role in other complications in the neonatal period.

Pulmonary trypsin-2 in the development of bronchopulmonary dysplasia in preterm infants

OBJECTIVES

In the preterm infant, lung injury can lead to irreversible tissue destruction and abnormal lung development. We examined whether pulmonary trypsin, a potent matrix-degrading serine proteinase and proteinase-cascade activator, is associated with the development of bronchopulmonary dysplasia (BPD) in preterm infants.

METHODS

Samples of tracheal aspirate fluid were collected from 32 intubated preterm infants during their first 2 postnatal weeks. The presence and molecular forms of trypsin in tracheal aspirate fluid samples were analyzed by zymography and Western blotting. The concentrations of trypsinogen-1 and -2 and tumor-associated trypsin inhibitor were measured by immunofluorometry. For examining the expression of trypsin-2 in lung tissue, immunohistochemistry was performed on autopsy specimens of fetuses, of preterm infants who died from respiratory distress syndrome or BPD, and of term infants without lung injury.

RESULTS

In infants who subsequently developed BPD (n = 18), we detected significantly higher concentrations of trypsinogen-2 during postnatal days 5 to 10 compared with those who survived without it. There was no difference in trypsinogen-1 concentrations. Tumor-associated trypsin inhibitor concentrations were significantly lower in infants who needed mechanical ventilation for >1 week. Immunohistochemistry demonstrated that trypsin-2 was predominantly expressed in bronchial and bronchiolar epithelium. In 2 preterm infants who died from prolonged respiratory distress syndrome, trypsin-2 was also expressed in vascular endothelium.

CONCLUSIONS

The levels of trypsinogen-2 are higher during postnatal days 5 to 10 in infants who subsequently develop BPD. The results suggest that high levels of pulmonary trypsin-2 may be associated with the development of BPD. This raises the possibility that therapy with exogenous proteinase inhibitors might prevent the development of BPD in preterm infants with respiratory distress.

Interleukin-4 and 13 concentrations in infants at risk to develop Bronchopulmonary Dysplasia

BACKGROUND

An exaggerated inflammatory response occurs in the first few days of life in infants who subsequently develop bronchopulmonary dysplasia (BPD). The increase of inflammatory cytokines in many disease processes is generally balanced by a rise in anti-inflammatory cytokines. Interleukin-4 (IL-4) and interleukin-13 (IL-13) have been shown to inhibit production of several inflammatory cytokines important in the development of BPD.

METHODS

We sought to determine if a correlation exists between the presence or absence of IL-4 and IL-13 in tracheal aspirates (TA) during the first 3 weeks of life and the development of BPD in premature infants. Serial TAs were prospectively obtained from 36 very low birth weight infants and IL-4 and IL-13 concentrations were determined by ELISA.

RESULTS

Infants who developed BPD (n = 19) were less mature (25.3 +/- 0.02 wks vs. 27.8 +/- 0.05 wks; p < 0.001), and had lower birth weights (739 +/- 27 g vs.1052 +/- 41 g; p < 0.001). IL-4 and IL-13 were detectable in only 27 of 132 and 9 of 132 samples assayed respectively. Furthermore, the levels detected for IL-4 and IL-13 were very low and did not correlate with the development of BPD.

CONCLUSIONS

TA concentrations of IL-4 and IL-13 do not increase significantly during acute lung injury in premature infants.

Decreased interleukin-10 in tracheal aspirates from preterm infants developing chronic lung disease

The inability to balance pulmonary injury with healing may predispose preterm infants to chronic lung disease (CLD). It is postulated that the production of interleukin (IL)-10, an anti-inflammatory cytokine, is gestationally influenced and that CLD-prone infants may have a reduced ability to produce IL-10.

METHODS

Tracheal fluid (TF) was collected at least twice weekly from 48 mechanically ventilated infants within the first 7 d of life while intubated.

RESULTS

A total of 87 TF specimens were obtained. None of the 11 CLD infants (24-31 wk of gestation) had TF IL-10 levels above 4 pg/ml (0/20 TF specimens), while 14 (70%) of the 20 non-CLD preterm infants (27-36 wk of gestation) had IL-10 levels above 5 pg/ml in one or more of their TF specimens (18/48 TF specimens, p < 0.001). Only the 5 term infants who were ventilated for severe lung disease had raised IL-10 levels (17 infants, 5/19 TF specimens). IL-10 levels, if detected, (range 6-938 pg/ml) tended to be higher with increasing gestation (Spearman's rho coefficient = 0.43; p = 0.003). TF IL-10 detection was not associated with hyaline membrane disease, antenatal steroids or influenced by TF sample volume. Overall IL-8 levels were wide ranging but towards the end of week 1 the levels were significantly higher in CLD infants (CLD: median 34 184 ng/ml, preterm non-CLD: median 699 ng/ml, p < 0.001, term: 2961 ng/ml, p = 0.028).

CONCLUSION

A gestationally influenced low IL-10 may predispose preterm infants to persistent pulmonary inflammation of CLD.

Increased interleukin-8 and monocyte chemoattractant protein-1 concentrations in mechanically ventilated preterm infants with pulmonary hemorrhage

Pulmonary hemorrhage (PH) is a serious complication causing acute respiratory distress in the premature infant, and it is associated with significant mortality and morbidity. The role of inflammatory mediators in this condition is largely undefined. Serial tracheal aspirates (TA) were obtained at intervals from 65 mechanically ventilated infants with birth weights less than 1,250 g during the first 21 days of life. Clinically significant PH developed in 15 infants. TA concentrations of interleukin-8 (IL-8) and monocyte chemoattractant protein-1 (MCP-1) were determined by enzyme-linked immunosorbent assay (ELISA).PH was associated with an increased risk of death, bronchopulmonary dysplasia, intraventricular hemorrhage, and prolonged need for mechanical ventilation and supplemental oxygen. TA aspirate concentrations of IL-8 and MCP-1 (P = 0.001, ANOVA) were significantly increased in infants with PH compared to infants who did not develop this condition. TA cytokine concentrations were also significantly increased in infants who developed bronchopulmonary dysplasia (BPD). Peak TA concentrations of IL-8 and MCP-1 were significantly higher in infants with poor outcome (BPD or death). TA MCP-1 but not IL-8 concentrations were significantly higher in infants who were oxygen-dependent at 36 weeks postconceptional age. These data suggest a pathogenic role for IL-8 and MCP-1 in the development of adverse pulmonary outcome in preterm infants with clinically significant PH.

Matrix metalloproteinases-2, -8, and -9 and TIMP-2 in tracheal aspirates from preterm infants with respiratory distress

OBJECTIVES

Matrix metalloproteinases (MMPs) are a family endoproteinases that act in degradation of extracellular matrix and basement membranes. The development of bronchopulmonary dysplasia (BPD) is characterized by early pulmonary inflammation, increased microvascular permeability, and subsequently by disordered repair. The aims of our study were to characterize the presence and molecular weight forms of MMP-2, -8, and -9 and their specific inhibitor, tissue inhibitor of metalloproteinases (TIMP)-2, in lungs of preterm infants during the early postnatal period and to determine whether levels of these MMPs and TIMP-2 in tracheal aspirate fluid (TAF) are associated with acute or chronic lung morbidity of the preterm infant.

METHODS

TAF samples were collected from 16 intubated preterm infants (gestational age 27.0 +/- 2.0 weeks; birth weight 875 +/- 246 g) during their first 5 postnatal days. The presence and molecular weight forms of MMPs and TIMP-2 were identified by Western immunoblotting, and their levels were evaluated by densitometric scanning.

RESULTS

MMP-8 in TAF was higher in infants who needed treatment with surfactant (25.4 +/- 6.3 vs 10.6 +/- 1.5 arbitrary unit/secretory component of immunoglobulin A [AU/SC]) and in whom BPD developed (N = 6; 27.6 +/- 5.2 vs 15.1 +/- 5.0 AU/SC). TIMP-2 levels were lower in infants with initial arterial to alveolar oxygen tension ratios <0.22 (2.7 +/- 1.1 vs 16.8 +/- 7.4 AU/SC) and in infants needing mechanical ventilation for >1 week (5.2 +/- 2.1 vs 22.8 +/- 11.7 AU/SC).

CONCLUSIONS

In preterm infants, an imbalance between pulmonary MMP-8 and TIMP-2 participates in the acute inflammatory process in respiratory distress syndrome and may contribute to the development of chronic lung injury.

Monocyte chemoattractant protein-1 and interleukin-8 are increased in bronchopulmonary dysplasia: relation to isolation of Ureaplasma urealyticum

BACKGROUND

An exaggerated inflammatory response occurs in infants who subsequently develop bronchopulmonary dysplasia (BPD). Ureaplasma urealyticum (Uu) is frequently isolated from cultures of tracheal secretions obtained from very low birth weight infants and is associated with an increased risk of BPD.

METHODS

We examined the relationships between isolation of genital mycoplasmas, tracheal aspirate (TA) interleukin-8 (IL-8), and monocyte chemoattractant protein-1 (MCP-1) concentrations and the development of BPD. Serial TAs were obtained prospectively from 35 very low birth weight infants, and IL-8 and MCP-1 concentrations were determined by enzyme-linked immunoadsorbent assay. Tracheal cultures for bacteria and genital mycoplasmas were performed on aspirates obtained during the first 2 days of life.

RESULTS

Infants who developed BPD (n=18) were less mature (25.2+/-0.2 vs 27.8+/-0.5 weeks; P<0.001), of lower birth weight (746+/-28 vs 1052+/-41 g; P<0.001), and more likely to have a positive tracheal culture for Uu (39% vs 6%; P=0.026) than those who did not develop BPD (n=17). Tracheal concentrations of IL-8 and MCP-1 were significantly increased in infants who developed BPD (IL-8: P=0.0001; MCP-1: P<0.001, analysis of variance) and correlated with duration of mechanical ventilation and oxygen treatment. Uu-positive infants had an increased incidence of BPD (88% in infants with Uu vs 42% in infants without Uu; P=0.020) and had TA concentrations of IL-8 and MCP-1 that were significantly increased compared with those of Uu-negative infants.

CONCLUSIONS

Increased TA concentrations of IL-8 and MCP-1 during the first 2 weeks of life are associated with the development of BPD. Recovery of Uu from TAs is associated with a more robust inflammatory reaction and an increased risk of BPD.

Measurement of interleukin 10 in bronchoalveolar lavage from preterm ventilated infants

BACKGROUND

Interleukin 10 (IL-10) is a cytokine that downregulates inflammation, in part by reducing the production of the proinflammatory cytokines IL-1beta and IL-8. It has been suggested that an inability to produce IL-10 might predispose preterm infants to develop chronic lung disease.

AIM

To measure IL-10, IL-1beta, and IL-8 in bronchoalveolar lavage fluid from ventilated preterm infants in a prospective cohort study.

PATIENTS

17 consecutive newborn infants < or = 29 weeks' gestational age (median, 25; 9 boys) who were ventilated from birth underwent daily bronchoalveolar lavage sampling.

RESULTS

102 samples were collected, of which 57 contained IL-10 in amounts that were comparable with those found previously in ventilated term infants with respiratory failure. Chronic lung disease developed in 9 of the 11 survivors and all 9 infants had produced IL-10. IL-1beta and IL-8 were detected in nearly all samples and were raised throughout the course of sample collection.

CONCLUSION

IL-10 is readily detectable in early bronchoalveolar lavage samples from ventilated preterm infants, although it remains unclear whether this cytokine has any influence on the development of chronic lung disease.

Links between early adrenal function and respiratory outcome in preterm infants: airway inflammation and patent ductus arteriosus

OBJECTIVE

To investigate the relationship of cortisol concentrations during the first week of life to patent ductus arteriosus (PDA), markers of lung inflammation, and respiratory outcome in very low birth weight infants.

METHODS

Newborns <1,500 g birth weight were prospectively enrolled at 2 centers. Serum cortisol was measured 3 times during days 2 to 7 of life. Tracheal lavage was performed on intubated infants and analyzed for interleukin-1beta, -6, and -8, and for total protein, albumin, and alpha-1 protease inhibitor. Infants receiving prenatal glucocorticoids were excluded.

RESULTS

We obtained 337 cortisol values from 125 infants. Infants treated for PDA had lower cortisol values after day 2. One hundred thirty-three tracheal fluid samples were obtained on matching days from 71 intubated infants. Cortisol correlated inversely with tracheal interleukins and proteins. Lower cortisol values during the second half of the week correlated with longer duration of supplemental oxygen therapy and with subsequent development of chronic lung disease at 28 days and at 36 weeks.

CONCLUSION

Infants with lower cortisol values in the first week of life had an increased incidence of PDA, increased lung inflammation, and an increased incidence of chronic lung disease. These findings suggest that early adrenal insufficiency may underlie the previously observed association of increased lung inflammation and PDA with adverse respiratory outcome in this population.

Validity of markers of dilution in small volume lung lavage

Definitive analysis of solute concentrations in lung lavage fluid involves the use of a marker of dilution to correct for variable recovery of epithelial lining fluid (ELF), but the question of the most appropriate dilutional marker remains unresolved. In lavage fluid collected from infants with lung disease and healthy control subjects, we examined ELF concentration of protein, albumin, sphingomyelin (SM), and IgA secretory component (SC), and critically appraised the relative validity of SC and urea as dilutional markers in the context of lung infection and lung injury. Protein, albumin, and SM were found not to be valid dilutional markers, as their ELF concentration varied significantly between the diseased, recovering, and normal lung. Differences in concentration were noted in both tracheal aspirate samples (TA, 4 x 0.5 ml) and nonbronchoscopic bronchoalveolar lavage fluid (NB-BAL, 3 x 1 ml/kg), but were not uniform (e.g., TA-disease versus control: albumin 2.8 versus 0.68 mg/ml, SM 45 versus 16 microgram/ml, both p < 0.05; NB-BAL-disease versus recovery: protein 8.1 versus 4.8 mg/ml, albumin 2.9 versus 1. 4 mg/ml, both p < 0.05). Overall, SC concentrations in ELF were not different between the diseased and normal lung, but in the NB-BAL samples, significantly higher SC concentration was noted in viral bronchiolitis and pneumonia than in noninfective lung diseases. No clear evidence of additional influx of urea into lavage fluid in association with epithelial disruption was found in the diseased lung. Comparative analysis of SC and urea revealed no difference in TA samples, but in NB-BAL specimens, urea best standardized the lavage concentration of surfactant indices to correspond to the degree of lung dysfunction as indicated by oxygenation index. We conclude that SC and urea, but not protein, albumin, or SM, are valid dilutional markers with which to estimate ELF recovery during small volume lung lavage. Urea appears a more appropriate choice in return fluid derived from the distal tracheobronchial tree, and SC should not be used in the context of lung infection.

Comparison of pulmonary inflammatory mediators in preterm infants treated with intermittent positive pressure ventilation or high frequency oscillatory ventilation

Ventilated preterm infants prone to the development of bronchopulmonary dysplasia have been shown to have increased inflammatory mediators in their tracheal aspirates. High frequency oscillatory ventilation (HFOV) is thought to be less traumatic than intermittent positive pressure ventilation (IPPV) in premature infants with surfactant deficiency, and therefore may reduce the inflammatory response in tracheobronchial aspirates. We randomized 76 premature infants requiring mechanical ventilation (birth weight 420-1830 g, median 840 g, gestational age 23 3/7 to 29 2/7 wk, median 26 4/7 to receive either an IPPV with a high rate (60-80/min) and low peak pressures, or an HFOV aiming at an optimization of lung volume, within 1 h of intubation. Tracheal aspirates were systematically collected during the first 10 d of life and analyzed for albumin, IL-8, leukotriene B4 (LTB4), and the secretory component (SC) for IgA as a reference protein. Bacterially colonized samples were excluded. On the treatment d 1, 3, 5, 7, and 10, the resulting median values of albumin (milligrams/mg of SC) were 28, 23, 24, 18, and 10, in IPPV-ventilated infants, and 33, 28, 18, 25, and 39 in HFOV-ventilated infants, respectively. Median IL-8 values (nanograms/mg of SC) were 671, 736, 705, 1362, and 1879 (IPPV) and 874, 1713, 1029, 1426, and 1823 (HFOV), respectively, and median LTB4 values (nanograms/mg of SC) were 26, 13, 27, 22, and 11 (IPPV) and 15, 12, 7, 12, and 16 (HFOV), respectively. Values were similar in IPPV- and HFOV-ventilated infants, and no significant differences were noted. We conclude that HFOV, when compared with a high rate low pressure IPPV, does not reduce concentrations of albumin, IL-8, and LTB4 in tracheal aspirates of preterm infants requiring mechanical ventilation.

Plasma proteins in acute and chronic lung disease of the newborn

This study compared plasma levels of albumin, transferrin, and ceruloplasmin in well preterm babies (n = 21) with those with respiratory distress syndrome (RDS, n = 13) and chronic lung disease (CLD, n = 13) over the first 28 postnatal days. Plasma lipid peroxidation, total radical trapping capacity (TRAP assay), and iron binding antioxidant capacity were also measured. In RDS and CLD albumin levels were decreased on days 1, 4 and 10; on day 10 albumin was lower in CLD compared to RDS (p < .05). After day 10 the levels were similar in all groups. The transferrin levels showed a similar trend. Ceruloplasmin levels did not differ, except for a higher day 28 level in CLD (p < .05). Albumin levels significantly decreased with increasing FiO2 and duration of oxygen therapy (within patient r = -0.30, p < .05 and r = -0.51, p < .005, respectively). On day 10, increasing oxygen therapy increased plasma lipid peroxidation (r = +0.49, p < .01), which was also significantly related to lower plasma protein levels (r = -0.42, p < .01). Lower plasma albumin and transferrin lowered the TRAP and iron binding antioxidant capacity, respectively (r = +0.36, p < .05, and r = +0.41, p < .005). Prediction of CLD using day 10 albumin levels had a specificity of 94%, but a sensitivity of only 50%. The interaction between oxygen toxicity and high ventilation pressures in immature babies appears to lower plasma proteins by increasing pulmonary permeability. The lower plasma albumin level was not useful in predicting the development of CLD; however, the fall in plasma transferrin and albumin will further decrease the preventive and chain-breaking antioxidant capacity of plasma of these ill babies.

Simplified method for purification of colostrum to obtain secretory component of immunoglobulin A, using secretory component as a reference protein in tracheal aspirate fluid

Many studies employ bronchoalveolar lavage fluid for assessment of biologically active substances secreted from the lung. However, investigators continue to search for a useful reference standard to correct for the inevitable but variable degree of dilution of this fluid. The glycoprotein, soluble secretory component of IgA, may serve as a valid reference protein. We report a simplified method for the purification of secretory component from colostrum. Soluble secretory component was isolated from human colostrum using serial centrifugation, size-exclusion fractionation and ion-exchange chromatography. Secretory component rich fractions were assayed by enzyme immunoassay. They were also evaluated for total amino acid content and distribution and sequence determination with satisfactory agreement with published results. We then demonstrated that soluble secretory component concentration in tracheal aspirate fluid did not correlate with either albumin or with total protein measured in the same samples. Therefore, we conclude that the secretory component of IgA serves as a useful reference marker because its use may avoid errors resulting from leakage of plasma proteins into epithelial lining fluid. Advantages of this method for establishing a standard for secretory component include ready availability of soluble secretory component, simplicity of the method and relative rapidity of the techniques.

Eight-epi-PGF2alpha: a possible marker of lipid peroxidation in term infants with severe pulmonary disease

A prostaglandin F2-like compound, 8-epi-PGF2alpha, formed from oxidation of arachidonate, has been proposed as an indicator of lipid peroxidation. We determined whether tracheal aspirate or urinary 8-epi-PGF2alpha levels would differ over time or between infants in a control group and infants with severe respiratory failure. We correlated tracheal aspirate 8-epi-PGF2alpha levels with the fraction of inspired oxygen and with mean airway pressures at 24 and 48 hours of life. Levels in tracheal aspirates were in the range of 0 to 36 pg/microg of fSC of IgA and were higher in infants with severe pulmonary disorders compared with those in infants in the control group (p < 0.02). Urinary concentrations did not discriminate between sick infants and infants in the control group.

Pulmonary surfactant concentration during transition from high frequency oscillation to conventional mechanical ventilation

OBJECTIVE

To test the hypothesis that conventional mechanical ventilation (CV) provides a greater stimulus to secretion of pulmonary surfactant than high frequency oscillatory ventilation (HFO).

METHODOLOGY

Sequential examination of surfactant indices in lung lavage fluid in a group of six infants with severe lung disease (group 1), ventilated with HFO and then converted back to CV as their lung disease recovered. A similar group of 10 infants (group 2) ventilated conventionally throughout the course of their illness were studied for comparison. In groups 1 and 2, two sequential tracheal aspirate samples were taken, the first once lung disease was noted to be improving, and the second 48-72 h later. Group 1 infants had converted from HFO to CV during this time.

RESULTS

A marked increase in concentration of total surfactant phospholipid (PL) and disaturated phosphatidylcholine (DSPC) was seen in group 1 after transition from HFO to CV; the magnitude of this increase was significantly greater than that sequentially observed in group II (total PL: 9.4-fold increase in group 1 vs 1.8-fold in group 2, P = 0.006; DSPC: group 1 6.4-fold increase vs. group 2 1.7-fold, P = 0.02).

CONCLUSION

These findings suggest that intermittent lung inflation during CV produces more secretion of surfactant phospholipid than continuous alveolar distension on HFO, and raise the possibility that conservation and additional maturation of surfactant elements may occur when the injured lung is ventilated with HFO.

Elevated laminin concentrations in lung secretions of preterm infants supported by mechanical ventilation are correlated with radiographic abnormalities

OBJECTIVE

The objective of this study was to test the hypothesis that the presence of laminin in neonatal tracheal aspirates would be indicative of damage to the structural integrity of the basal laminae of the lung caused by barotrauma and hyperoxia. We predicted that disruption of the basal laminae would be a critical determinant of lung injury and fibrotic repair in the preterm infant whose lungs were ventilated with supplemental oxygen.

STUDY DESIGN

The study group consisted of 23 premature infants in the neonatal intensive care unit whose lungs were ventilated by supplemental oxygen. We quantitated concentrations of laminin and fibronectin from sequential tracheal aspirates by enzyme-linked immunosorbent assays. A two-way analysis of variance was used to compare laminin and fibronectin concentrations in infants with and without radiographic evidence of coarse pulmonary markings indicative of fibrotic repair of lung injury.

RESULTS

The concentrations of laminin, but not fibronectin, were significantly higher throughout the first 5 weeks of life in infants with abnormal chest radiographs at 36 weeks after conception. The concentrations of laminin in infant serum were approximately 1/30 that of tracheal aspirate laminin concentrations, suggesting that little if any of the laminin detected in the tracheal aspirates was derived from the serum.

CONCLUSIONS

Increased concentrations of laminin in tracheal aspirates may be an indication of lung injury and fibrotic repair in the preterm infant.

Early production of macrophage inflammatory protein-1 alpha occurs in respiratory distress syndrome and is associated with poor outcome

Although progression to pulmonary fibrosis in preterm infants with respiratory distress syndrome (RDS) is related to the inflammatory response, the nature of this response remains controversial. We have therefore performed sequential bronchoalveolar lavages in 30 infants with RDS (13 of whom developed bronchopulmonary dysplasia) and 7 ventilated control infants, characterizing the cells obtained by immunohistochemical analysis of lineage-specific markers and assaying macrophage-associated chemokines and cytokines in supernatant fluid. At all ages from birth, lavage supernatants demonstrated highly significant increase over controls of the beta-chemokine macrophage inflammatory protein (MIP)-1 alpha, although not of regulated upon activation, normal T cell expressed and secreted (RANTES), of the cytokines tumor necrosis factor (TNF)-alpha and IL-1 beta, and of elastase/alpha-1 antitrypsin. Significantly higher concentrations of MIP-1 alpha in particular were associated with the later development of fibrosis. Increased numbers of macrophages expressing the activation marker RM/3-1 were found at all ages in bronchopulmonary dysplasic infants, whereas neutrophil numbers were increased from d 3. Dexamethasone administered to 10 infants induced rapid decrease in inflammatory cell numbers and concentrations of MIP-1 alpha, tumor necrosis factor-alpha, IL-1 beta, and elastase/alpha-1 antitrypsin. The inflammatory response in neonatal RDS begins within the first day of life. Long-term outcome is associated with the magnitude of this early response, in particular production of MIP-1 alpha. The early introduction of specific therapy is thus likely to be beneficial.

Dexamethasone therapy in chronic lung disease

Steroids have been used in the treatment of infants with chronic lung disease (CLD) for over a decade. Some studies have reported beneficial effects from long, tapering 42-day course of dexamethasone. Short term regimens have also shown beneficial effects on ventilator dependent infants with CLD. Although steroid therapy has been successful in infants with established CLD, more recently, dexamethasone therapy is being initiated in infants with RDS considered to be at risk for developing CLD. Some of the initial studies reported higher rates of infection, but more recent prospective data have not shown an increased incidence of sepsis in patients treated with steroids. Presently, early steroid therapy appears to be beneficial to minimize lung injury in infants treated with surfactant.