Nonassociation of Interleukin 4 Intron 3 and 590 Promoter Polymorphisms with Bronchopulmonary Dysplasia for Ventilated Preterm Infants

Interleukin 4 (IL-4) stimulates and amplifies the inflammatory response, stimulates collagen synthesis in fibroblasts, promotes the progression to fibrosis and has been shown to inhibit the production of several inflammatory cytokines in the development of bronchopulmonary dysplasia (BPD) and airway hyperreactivity. We aimed to investigate whether IL-4 polymorphisms in ventilated preterm infants were associated with BPD. BPD was defined as infants who remained dependent on active respiratory support or oxygen supplementation at 36 weeks postconceptional age. A case-control study of 224 preterm infants (<30 weeks) who had respiratory distress syndrome and needed intermittent mandatory ventilation (IMV) were undertaken between January 1999 and December 2003. The typing of each genetic polymorphism was performed by polymerase-chain-reaction-based restriction analysis. Genotype distribution and allelic frequencies were compared between ventilated preterm infants who developed BPD and those who did not and the duration of IMV. The demography of these ventilated BPD and non-BPD preterm infants was not different. We observed no significant differences in genotype distribution or allelic frequency of the IL-4 intron 3 or IL-4 promoter polymorphisms between ventilated preterm infants who developed BPD and who did not. There was no significant association of the genotype or allelic frequency of IL-4 polymorphism with duration of IMV. We conclude that neither IL-4 intron 3 nor the 590 promoter polymorphism is a useful marker for predicting the susceptibility to BPD in ventilated Taiwanese preterm infants.

Developmental regulation of p66Shc is altered by bronchopulmonary dysplasia in baboons and humans

RATIONALE

The p66(Shc) adapter protein antagonizes mitogen-activated protein, or MAP, kinase, mediates oxidative stress, and is developmentally regulated in fetal mouse lungs.

OBJECTIVES

To determine if p66(Shc) is similarly regulated in primates and in bronchopulmonary dysplasia (BPD), which results from oxidative injury to immature lungs.

METHODS

Normal and injured lungs from humans and baboons were evaluated by Western analysis and immunohistochemistry.

MEASUREMENTS AND MAIN RESULTS

In baboons, p66(Shc) decreased 80% between 125 and 175 days' gestation (p = 0.025), then doubled after term delivery at 185 days (p = 0.0013). In the hyperoxic 140-day fetal baboon BPD model, p66(Shc) expression persisted, and its localization shifted from the epithelium of gestational controls to the mesenchyme of diseased lungs, coincident with expression of proliferating cell nuclear antigen and cleaved poly(adenyl ribose) polymerase, a marker of apoptosis. Treatment with the antibombesin antibody 2A11 attenuated BPD, reduced cell proliferation, increased p66(Shc) expression 10.5-fold, and preserved epithelial p66(Shc) localization. p66(Shc) also decreased during normal human lung development, falling 87% between 18 and 24 weeks' gestation (p = 0.02). p66(Shc) was expressed throughout 18-week human lungs, became restricted to scattered epithelial cells by 24 weeks, and localized to isolated mesenchymal cells after term delivery. In contrast, p66(Shc) remained prominent in the epithelium of lungs with acute injury or mild BPD, and in the mesenchyme of lungs with severe disease. p66(Shc) localized to tissues expressing proliferating cell nuclear antigen and cleaved poly(adenyl ribose) polymerase.

CONCLUSIONS

p66(Shc) expression, cell proliferation, and apoptosis are concomitantly altered during lung development and in BPD.

The Angiotensin Converting Enzyme Insertion/Deletion polymorphism is not associated with an increased risk of death or bronchopulmonary dysplasia in ventilated very low birth weight infants

BACKGROUND

The ACE gene contains a polymorphism consisting of either the presence (insertion, I) or absence (deletion, D) of a 287 bp alu repeat in intron 16. The D allele is associated with increased ACE activity in both tissue and plasma. The DD genotype is associated with risk of developing ARDS and mortality. The frequency of the D allele is higher in patients with pulmonary fibrosis, sarcoidosis and berylliosis. The role of this polymorphism has not been studied in the development of BPD in the premature newborn.

METHODS

ACE I/D genotype was determined in 245 (194 African-American, 47 Caucasian and 4 Hispanic) mechanically ventilated infants weighing less than 1250 grams at birth and compared to outcome (death and/or development of BPD).

RESULTS

The incidence of the D allele in the study population was 0.58. Eighty-eight (35.9%) infants were homozygous DD, 107 (43.7%) were heterozygous ID and 50 (20.4%) were homozygous II. There were no significant differences between genotype groups with respect to ethnic origin, birth weight, gestation, or gender. There was no effect of the ACE I/D polymorphism on mortality or development of BPD (O2 on 28 days or 36 weeks PCA). Secondary outcomes (intraventricular hemorrhage and periventricular leukomalacia) similarly were not influenced by the ACE ID polymorphism.

CONCLUSIONS

The ACE I/D polymorphism does not significantly influence the development of BPD in ventilated infants less than 1250 grams.

Surfactant protein C gene variation in the Finnish population - association with perinatal respiratory disease

Surfactant protein C (SP-C) is a small hydrophobic protein component of alveolar surfactant, a lipid-protein complex lining the alveolar surface of the lung. Surfactant deficiency is the main cause of respiratory distress syndrome (RDS) in premature infants. RDS is a major risk factor of a chronic lung disease called bronchopulmonary dysplasia (BPD). The dominant mutations of the SP-C gene have recently been associated with interstitial lung diseases. However, the common genetic variation in the surfactant protein C gene has not been studied in detail. In the present study, the exonic variation of the SP-C gene in the Finnish population (n=472) was defined, and the association of the allelic variants with the susceptibility to RDS and BPD was examined. Conformation-sensitive gel electrophoresis (CSGE) was used to determine the extent of exonic variation in the SP-C gene. Methods of genotyping were generated for three biallelic polymorphisms of the SP-C gene's exons 1, 4 and 5, which encode proSP-C. The frequencies of these polymorphisms were evaluated in a study population consisting of 158 DNA samples from full-term infants. In addition, the linkage disequilibrium between the SP-C alleles was evaluated by haplotype analysis of parent-infant triplets. The role of SP-C gene variation in RDS and in BPD was evaluated in a high-risk population of 245 premature infants. According to the present results, the SP-C polymorphisms were associated with RDS and with very premature birth. The strength of allelic associations differed according to the gender of the premature infants.

No association of urokinase gene 3'-UTR polymorphism with bronchopulmonary dysplasia for ventilated preterm infants

Pathological findings pertaining to bronchopulmonary dysplasia (BPD) are consistent with a process of prolonged lung inflammation and impaired healing. The balance of the competing activities of coagulation and fibrinolysis may contribute to the premature lung's response to acute injury. We investigated the association of the urokinase gene polymorphism with BPD in ventilated preterm infants whose gestational age was below 30 weeks. BPD is defined as infants remaining dependent upon active respiratory support and/or oxygen supplementation and featuring characteristic radiographic changes in the lung fields on the 28th postnatal day (BPD-28d) and at a corrected age of 36 weeks of gestation (BPD-36w). Two hundred and four ventilated preterm infants were enrolled in the study. The typing of each specific genotype polymorphism was performed by polymerase chain reaction (PCR) and restriction analysis. Perinatal risk factors for BPD, genotype distribution, and allelic frequencies were compared between infants suffering from BPD (28-d), BPD (36-w) and their respective ventilated preterm infants who did not develop BPD infants. The genotype proportions of the urokinase 3'-UTR polymorphism for BPD (28-d), BPD (36-w) and their respective ventilated preterm infants who did not develop BPD did not differ significantly. There was no difference in allelic frequency for the urokinase 3'-UTR polymorphism between BPD (28-d), BPD (36-w) and their respective ventilated preterm infants who did not develop BPD infants. We concluded that urokinase gene 3'-UTR C/T polymorphism is not a suitable marker for predicting susceptibility and severity to BPD for preterm infants of Taiwanese.

Bronchopulmonary dysplasia: new insights

The pathology of BPD has changed over time, with the old BPD characterized by airway injury, inflammation, and parenchymal fibrosis giving way to the new BPD manifesting less fibrosis but with decreased alveolar and vascular development. The pathogenesis of BPD involves factors affecting the severity and management of RDS, alterations in lung development and maturation, alveolar-vascular interactions, and extracellular matrix remodeling. These factors in pathogenesis are mediated and modulated by hyperoxic lung injury, antioxidants, NO, the pulmonary neuroendocrine system and peptide growth factors, the immune system, and various genetic polymorphisms and predispositions. Future therapeutic interventions are likely to target one or more of these abnormalities in lung development, maturation, and response to injury.

Conditional overexpression of bioactive transforming growth factor-beta1 in neonatal mouse lung: a new model for bronchopulmonary dysplasia?

Research interest in bronchopulmonary dysplasia (BPD) has steadily increased, and numerous potential mediators have been implicated in the development of the disease. Among such mediators is transforming growth factor (TGF)-beta. Unfortunately, commonly utilized murine transgenic models are not optimal to investigate the effects of TGF-beta specifically during the 2-3 wk period of alveolar formation, the developmental stage that corresponds histologically to early alveolar development in humans, and the time frame during which BPD develops. In the current study, we utilized a triple-transgenic construct to overexpress bioactive TGF-beta1 in the neonatal mouse lung during the period of alveolar formation. Lungs were then examined by histologic, Western blot, and immunofluorescent methods. We found that overexpression of bioactive TGF-beta1 in neonatal mouse lungs resulted in structural changes that have been described in BPD. Included in those characteristics are abnormal alveolar structure, cellular composition, and vascular development. Our study indicates that TGF-beta1 overexpression in the neonatal mouse lung results in histologic alterations that have striking similarities to pathologic descriptions of BPD. We encourage the use of conditional transgenic models for the study of BPD, and hypothesize that the TGF-beta system is a central mediator for the histologic alterations described in association with the disease.

Polymorphism of tumor necrosis factor-alpha and risk and severity of bronchopulmonary dysplasia among very low birth weight infants

BACKGROUND

Preterm infants with bronchopulmonary dysplasia (BPD) exhibit prolonged elevation of inflammatory indices in their tracheal aspirates. Tumor necrosis factor-alpha (TNF-alpha) is a central mediator of the inflammatory response. The adenine-containing alleles of TNF-alpha-308 and lymphotoxin-alpha+250 have been associated with increased levels of TNF-alpha, whereas the adenine allele of TNF-alpha-238 produces lower levels of TNF-alpha after stimulation. High levels of TNF-alpha may promote chronic inflammation by overwhelming counter-regulatory mechanisms and may lead to the development of BPD. Low levels of TNF-alpha may decrease the risk and/or severity of BPD.

OBJECTIVE

To determine whether alleles of TNF-alpha play a role in the susceptibility and/or severity of BPD among very low birth weight infants.

METHODS

Infants with birth weights of < or =1250 g were included. Genotypic analyses (polymerase chain reaction-restriction fragment length polymorphism assays) were performed with DNA extracted from whole-blood samples.

RESULTS

Infants who developed BPD (fraction of inspired oxygen at postconceptional age of 36 weeks of >0.21, n = 51) had a younger gestational age (mean +/- SD: 27 +/- 4 vs 29 +/- 2 weeks) and lower birth weight (853 +/- 184 vs 997 +/- 193 g) than did infants without BPD (n = 69). The genotypic distributions of lymphotoxin-alpha+250 and TNF-alpha-308 were comparable among the groups of infants. However, the AA and GA TNF-alpha-238 genotypes were much less likely to occur among infants with BPD than among infants without BPD. The adenine allele of TNF-alpha-238 was absent among infants with severe BPD and occurred significantly less often among infants with moderate or severe BPD, compared with infants with mild BPD. The number of adenine alleles of TNF-alpha-238 was correlated inversely with the severity of BPD (r = -.341).

CONCLUSION

The adenine allele of TNF-alpha-238 may reduce the risk and severity of BPD.

Data mining and multiparameter analysis of lung surfactant protein genes in bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD), the most common chronic lung disease in infancy, is influenced by a number of antenatal and postnatal risk factors and is mostly preceded by respiratory distress syndrome (RDS) in the newborn. Surfactant protein (SP-A, -B, -C and -D) gene variations may play a role in both BPD and RDS. An association study between these candidate genes and BPD was performed. A total of 365 preterm Finnish infants in a high-risk population with gestational age <or=32 weeks were genotyped for all SP genes. A multiparameter analysis was performed using Agrawal's algorithm based data mining and conventional methods of statistical allelic association. In singletons and presenting multiples, the frequency of SP-B intron 4 deletion variant allele was increased in BPD versus controls (P=0.008, OR=2.0, 95%CI 1.2-3.4). The presence of the SP-B intron 4 deletion variant was a risk factor for BPD even when essential external confounding factors were included in the analyses. No other SP polymorphisms associated with BPD, and the SP-B intron 4 variation did not associate with RDS. Transcription Element Search Software predicted allele-specific differences at several putative transcription factor binding sites that may be important in SP-B regulation. The present multiparameter analysis demonstrates the presumable direct involvement of the SP-B intron 4 deletion variant allele as a genetic risk factor to BPD. We propose that two separate SP-B gene polymorphisms have a phenotypic significance via separate molecular mechanisms: the intron 4 length variation affecting transcriptional regulation, and the exonic Ile131Thr variation affecting post-translationally.

Gene expression profile and histopathology of experimental bronchopulmonary dysplasia induced by prolonged oxidative stress

Oxidative stress is an important factor in the pathogenesis of bronchopulmonary dysplasia (BPD), a chronic lung disease of premature infants characterized by arrested alveolar and vascular development of the immature lung. We investigated differential gene expression with DNA microarray analysis in premature rat lungs exposed to prolonged hyperoxia during the saccular stage of development, which closely resembles the development of the lungs of premature infants receiving neonatal intensive care. Expression profiles were largely confirmed by real-time RT-PCR (27 genes) and in line with histopathology and fibrin deposition studied by Western blotting. Oxidative stress affected a complex orchestra of genes involved in inflammation, coagulation, fibrinolysis, extracellular matrix turnover, cell cycle, signal transduction, and alveolar enlargement and explains, at least in part, the pathological alterations that occur in lungs developing BPD. Exciting findings were the magnitude of fibrin deposition; the upregulation of chemokine-induced neutrophilic chemoattractant-1 (CINC-1), monocyte chemoattractant protein-1 (MCP-1), amphiregulin, plasminogen activator inhibitor-1 (PAI-1), secretory leukocyte proteinase inhibitor (SLPI), matrix metalloproteinase-12 (MMP12), p21, metallothionein, and heme oxygenase (HO); and the downregulation of fibroblast growth factor receptor-4 (FGFR4) and vascular endothelial growth factor (VEGF) receptor-2 (Flk-1). These findings are not only of fundamental importance in the understanding of the pathophysiology of BPD, but also essential for the development of new therapeutic strategies.

Potential role for antiangiogenic proteins in the evolution of bronchopulmonary dysplasia

Impaired neovascularization is associated with the pathologic presentation of bronchopulmonary dysplasia (BPD). To determine if neovascularization and factors that negatively influence blood vessel formation play a role in the evolution of BPD, we examined the temporospatial distribution of a protein known to inhibit fetal lung neovascularization with associated dysplastic lung formation, endothelial-monocyte activating polypeptide (EMAP) II. Immunohistochemical analysis of EMAP II in lung tissues of human infants with BPD indicated an elevation in EMAP II abundance as compared with control. Utilizing a baboon model, western analysis indicated that EMAP II was increased twofold in those baboons with pathologic signs of BPD as compared with gestational controls. Consistent with our findings in human tissues, immunohistochemistry and in situ hybridization demonstrate that EMAP II is highly expressed in the perivascular stroma and dysplastic lung periphery in neonatal baboons with BPD as compared with controls. Lastly, there is a premature acceleration in EMAP II's perivascular distribution in term newborn baboon as compared with gestational control. The marked increase in EMAP II's temporal expression, its distribution in the perivascular and dysplastic alveolar regions of the lungs, and the interruption in vasculogenesis in BPD suggest that neovascularization and factors that negatively influence blood vessel formation may play a role in BPD evolution.

Association of glutathione-S-transferase-P1 (GST-P1) polymorphisms with bronchopulmonary dysplasia

OBJECTIVE

Reactive oxygen species (ROS) contribute to oxidative lung injury. The glutathione-S-transferases (GST) family and microsomal epoxide hydrolase (mEPHx) enzymes detoxify ROS, and genetic polymorphisms alter this detoxification. We hypothesized that polymorphisms encoding for less efficient enzymes were associated with bronchopulmonary dysphasia (BPD).

STUDY DESIGN

We determined allelic distribution of these polymorphisms in a pilot study of 35 BPD cases and 98 controls. chi2 and regression analysis were performed.

RESULTS

GST P1 val105ile distribution differed between the groups, with the more efficient val/val allele predominantly in controls (p< or =0.05). When controlling for race and sex, BPD cases were less likely to be homozygotes for the val/val isoform (OR 0.21, CI: 0.045-0.95, p=0.04) and more likely to possess the less efficient ile isoform (OR 4.5, CI: 1.0-20.7, p=0.05).

CONCLUSIONS

This pilot study suggests that BPD is associated with the presence of the GST-P1 105ile allele. Future prospective studies are warranted.

Secretoglobins SCGB3A1 and SCGB3A2 define secretory cell subsets in mouse and human airways

Clara cell secretory protein (CCSP) is expressed abundantly within the conducting airway epithelium and is thought to have immunoregulatory functions. Differences in the localization of CCSP between mouse and human airways led us to hypothesize that functional homologues of CCSP may compensate for the lack of CCSP expression in proximal airway locations. We previously identified an expressed sequence tag (W82219) whose expression is induced within Clara cells of CCSP knockout mice. Expressed sequence tag W82219 is distantly related to CCSP and represents a member of a new subfamily of secretoglobins (MmSCGB3A2). Another member of the mouse SCGB3 family (MmSCGB3A1) as well as human orthologues (HsSCGB3A1 and HsSCGB3A2) that possess structural homology to CCSP were identified, suggesting they may share common functional properties. SCGB3A1 messenger RNA localizes to a subset of SCGB3A2-expressing cells within bronchi of both mouse and neonatal human lungs. CCSP, SCGB3A1, and SCGB3A2 were decreased in airways of neonates with bronchopulmonary dysplasia and in mice after airway injury. We conclude that secretory cells of the conducting airway epithelium express distinct members of the secretoglobin family in a partially overlapping fashion. Altered expression of secretoglobins in airway disease may contribute to immunoregulatory perturbations commonly seen in chronic airway disease.

Photoprotection prevents TPN-induced lung procollagen mRNA in newborn guinea pigs

BACKGROUND

Photo-exposed intravenous multivitamin solutions (MVP) carry a peroxide load. Peroxidation induces gene expression of procollagen. We hypothesized that photo exposure of the MVP solution might promote pulmonary fibrosis. The aim of the study was to assess the potential for MVP to increase procollagen mRNA.

METHODS

Three day old guinea pigs were assigned to the following intravenous regimens, either: Control (C): 5% dextrose + 0.45% NaCl; C + 200 or 500 microM H(2)O(2); C + 500 microM H(2)O(2) + 10 microM GSSG; [C + 1% MVP +/- [amino acids + lipids]] +/- photoprotected. After 4 d, levels of pulmonary alpha1(I) procollagen mRNA and glutathione were determined. Results were compared by ANOVA.

RESULTS

Photoprotection of MVP or TPN prevents light induction of procollagen mRNA. The effect of MVP + light was associated with a peroxide load coupled with a low glutathione level. This was also observed with the 500 microM H(2)O(2) group. The addition of GSSG prevented the increase of procollagen mRNA caused by H(2)O(2).

CONCLUSION

An oxidant stress caused by the infusion of peroxides in an organism with a weak antiperoxide capacity induces the transcription of the gene encoding for procollagen alpha1(I). The results confirm the antiperoxide activity of lung glutathione. Parenteral nutrition could be a clinical condition favoring the initiation of lung fibrosis, especially in premature newborn infants who have low glutathione levels.

Fetal hydrops and familial pulmonary lymphatic hypoplasia

Two siblings were born with pleural effusions and hydrops. The first infant was a 26-week-old gestation male and died at 8 hours of life with radiographically small lungs and pulmonary insufficiency. No lung tissue was obtainable. This pregnancy was followed by two normal term infants, a male and female. The fourth pregnancy resulted in a female born at 35 weeks' gestation with pleural effusion and hydrops who died at 32 months of age. This infant was discharged from hospital at 32 days of age with small pleural effusions, but needed supplemental oxygen and daily diuretics to control edema. There were 14 additional admissions until death-all for respiratory distress or infections. An open lung biopsy at 2 months, showed dilated pleural lymphatics, with hypoplasia of the acinar and terminal bronchiolar lymphatics. At postmortem examination there was a markedly thickened pleura, and slit-like hypoplastic lymphatics of the acinar and terminal bronchioles and interlobular septal regions. This is the second family reported with these distinctive pulmonary intra-acinar and peri-acinar hypoplastic lymphatics. This disease is compatible with an autosomal recessive mode of inheritance.

Do lung remodeling, repair, and regeneration recapitulate respiratory ontogeny?

Herein we posit that modeling of the lungs during morphogenesis, repair, and regeneration is tightly coordinated by conserved stimulatory and inhibitory signaling mechanisms, including specific transcriptional factors, cytokines, peptide growth factors, proteases, and matrix elements. This evolutionary-developmental (evo-devo) functional conservation has been extended to morphogenesis of the respiratory tracheae in Drosophila. Fifty or more genes direct fruit fly tracheal organogenesis. Among them, hedgehog, patched, smoothened, cubitus interruptus, branchless, breathless, sprouty, decapentaplegic, and mad are functionally conserved between flies, mice, and humans. For example, fibroblast growth factor (FGF) signaling is essential, not only for fly trachea and mouse bronchial branching morphogenesis, but also for postnatal modeling and repair of alveoli. Likewise, sprouty family genes act as inducible negative regulators of FGF signaling, which in part may determine interbranch length during bronchial development. Alveolar epithelial survival, migration, and proliferation during remodeling after hyperoxic injury also require FGF signaling. In addition, FGF signaling appears to regulate a small (< 5%) population of putative alveolar stem/ progenitor cells that express telomerase and are relatively resistant to hyperoxic apoptosis. We speculate that genes in evo-devo functionally conserved signaling pathways such as FGF-FGF receptor-Sprouty may provide novel therapeutic targets to augment lung repair and induce lung regeneration.

Polymorphisms of surfactant protein A genes and the risk of bronchopulmonary dysplasia in preterm infants

The pathophysiology of bronchopulmonary dysplasia (BPD) as an inflammatory disorder secondary to neonatal respiratory distress syndrome (RDS) is not yet fully understood and still represents a major complication of prematurity. The main pathophysiologic feature of RDS is a primary surfactant deficiency in a structurally immature lung. Pulmonary surfactant contains 90 percent phospholipids and 10 percent proteins (surfactant proteins A, B, C, and D). As surfactant protein A (SP-A) has several major immunological and metabolic intrapulmonary functions, we aimed at investigating an association of polymorphisms of SP-A1 and SP-A2 encoding genes and the risk of BPD. We performed a case-control study exclusively including Caucasian preterm infants below 32 weeks of gestation matched for the degree of immaturity and the year of birth. Venous cord blood was taken prospectively and analyzed by polymerase chain reaction (PCR), single-strand conformation polymorphism (SSCP), cloning and sequencing. BPD was defined as oxygen dependency or need for mechanical ventilation at day 28. Twenty-three infants with BPD were enrolled (mean gestational age 26.2 weeks; mean birth weight 760.4 g) and compared with 23 infants matched on the basis of gestational age (mean gestational age 27.9 weeks; mean birthweight 1015 g). We observed a significantly increased frequency of the SP-A1 polymorphism 6A6 in infants with BPD compared with controls. In addition to previously established risk factors for BPD, 6A6 polymorphism for SP-A1 gene is an independent co-factor. We believe treatment of neonatal RDS should also include stratification according to genetic risk factors.

Associations between family history of asthma, bronchopulmonary dysplasia, and childhood asthma in very low birth weight children

Very low birth weight (VLBW) infants are at risk for childhood wheezing and asthma, as are children with a family history of asthma. Family history of asthma may also be associated with premature labor and, among VLBW infants, with bronchopulmonary dysplasia (BPD) and chronic lung disease (CLD) of prematurity. This study targeted all neonates with birth weight <1,501 g who were admitted to seven perinatal centers in Wisconsin and Iowa between August 1, 1988 and June 30, 1991. Comprehensive information was collected for 723 of the 1,007 30-day survivors, and for 106 full-term controls. A representative subgroup of 257 VLBW children was contacted at age 5 years to ascertain bronchodilator and/or steroid use and diagnosis of asthma. Some evidence of an association between family history of asthma and premature birth was found, but it was not associated with neonatal BPD/CLD or BPD/CLD severity. Among BPD/CLD indicators, radiographic evidence of BPD at age 25-35 days was most strongly associated with bronchodilator use up to age 2 years (odds ratio (OR) = 10.1, 95% confidence interval (CI) 4.07-25.2) and with asthma between ages 2 years and 5 years (OR = 4.83, 95% CI 2.18-10.7). Among children without radiographic evidence of BPD, family history of asthma was associated with childhood asthma and bronchodilator use.

Evidence from twin study implies possible genetic susceptibility to bronchopulmonary dysplasia

To investigate the possibility that susceptibility to bronchopulmonary dysplasia (BPD) is affected by genetic factors, we analyzed risk factors for BPD in 108 twin pairs of infants having birth weight < or = 1,500 g. When BPD occurred in a first born twin (n = 23), it also occurred in 65% (n = 15) of the second born twins, and when BPD did not occur in the first twin (n = 85), it only occurred in 8% (n = 7) of the second twins (crude odds ratio = 20.9). After adjusting for potentially significant risk factors including birth weight, gestational age, gender, diagnosis of hyaline membrane disease, pneumothorax, symptomatic patent ductus arteriosus, and year of admission, using multiple logistic regression on the entire database (1,872 admissions < or = 1,500 g), BPD status of a first twin remained a highly significant predictor of BPD in the second twin (adjusted odds ratio = 12.3, P < .001). Other factors including birth order of twins, twin gestation, inborn/outborn status, cesarean section delivery, 1- and 5-minute Apgar scores, maternal race, maternal diabetes, and antepartum corticosteroid treatment were not significant predictors of BPD. These results are consistent with genetic factors affecting the susceptibility of very low birth weight premature infants to BPD, but we cannot exclude the possibility that factors not included in our analysis are also involved.

SP-A deficiency in primate model of bronchopulmonary dysplasia with infection. In situ mRNA and immunostains

The surfactant protein secretory cells in airway and alveolar epithelium were studied in premature baboons with bronchopulmonary dysplasia and superimposed infection. PRN animals were delivered by hysterotomy at 140 d gestational age and ventilated on clinically appropriate oxygen for a 16-d experimental period. To assess 0 time and sacrifice time gestational parameters, 140 and 156 d were studied. BPD animals were delivered at 140 d and ventilated with positive-pressure ventilation and an FIO2 of 1.0 for 11 d followed by 5 d of oxygen sufficient to maintain PAO2 at 40 to 50 mm Hg. BPD-infected animals were comparably ventilated and treated like the BPD group except that 10(8) E. coli organisms were endotracheally instilled on Day 11. In situ hybridization studies for mRNA expression of SP-A, SP-B, and SP-C revealed that an SP-A mRNA deficiency, present at 140 d, persisted in the BPD and BPD-infected groups, whereas SP-A mRNA was abundant in PRN and 156 d gestation control groups. SP-B and SP-C mRNA expression in the two hyperoxically injured groups was particularly extensive in cells around peribronchiolar and perivasicular sites. Immunostaining with SP-A, SP-B, and SP-C antibodies showed variable staining patterns. The study clearly demonstrates that a deficiency of SP-A mRNA expression persists in chronic lung injury and that variable protein staining patterns are manifested depending upon the underlying pathology.

[Surgical correction of bronchial stenosis: increased somatic development following elimination of the stenosis]

A 5 year old girl suffered from nearly total stenosis of the bronchus intermedius and exspiratory collaps of both main bronchi. Because of preterm birth she was postnatally intubated and mechanically ventilated for 6 weeks. Her somatic development was significantly retarded in comparison with the monozygotic twin, and pulmonary impairment increased again in the last preoperative year. By the combination of latest surgical technics (pericardial patch, interposition of a costal segment, fibrine glue) the bronchial abnormalities could be corrected successfully. In the first year after surgery catch-up growth was observed in the girl.

Diagnostic problems in asthma

Asthma can be over-diagnosed, but is more often under-diagnosed. The diagnosis can be made by demonstrating the reversibility of airway obstruction or by a provocation test if the baseline spirometry is normal. The most frequent causes of missing the diagnosis are (1) atypical clinical presentation, (2) misconceptions about age of onset of childhood asthma, and (3) the coexistence of another chronic respiratory illness that may have a more dramatic clinical picture and constitute a "red herring." It is fascinating to speculate on the similarities and differences between classical asthma (which has a usually completely reversible obstruction) and the hyperreactivity and partial reversibility of chronic inflammatory diseases like COPD or CF. Unfortunately much remains to be investigated and little is known at present about these questions. Even in classical asthma, chronic or recurrent inflammation (even by late allergic reaction) could worsen the basic hyperreactivity and this could be amenable to treatment or prevention.

Controlled trial of dexamethasone therapy in infants with bronchopulmonary dysplasia

Dexamethasone was compared with placebo in a double-blind, crossover, randomised study of infants with severe bronchopulmonary dysplasia who had required mechanical ventilation for at least four weeks, despite treatment with diuretics, methylxanthines, bronchodilators, fluid restriction, nutritional supplementation, and ligation of the patent ductus arteriosus when indicated. Gestational age ranged from 27 to 33 weeks and birth weight from 800 to 1730 g. Patients received dexamethasone (0 . 5 mg/kg/day) or normal saline for the first 3 days, then treatment was crossed over for the next 3 days. The study was terminated when sequential analysis showed that all six patients had improved during dexamethasone therapy. Significant improvements were seen in ventilator-determined respiratory rate, peak inspiratory pressure, fractional inspired oxygen concentration, and alveolar arterial oxygen gradients (p less than 0 . 05). Although dexamethasone hastened weaning from mechanical ventilation, infection occurred in a substantial proportion of patients.