Wilson-Mikity syndrome: updated diagnostic criteria based on nine cases and a review of the literature

Genetics of bronchopulmonary dysplasia: An update

Bronchopulmonary dysplasia (BPD) is a multi-factorial disease that results from multiple clinical factors, including lung immaturity, mechanical ventilation, oxidative stress, pulmonary congestion due to increasing cardiac blood shunting, nutritional and immunological factors. Twin studies have indicated that susceptibility to BPD can be strongly inherited in some settings. Studies have reported associations between common genetic variants and BPD in preterm infants. Recent genomic studies have highlighted a potential role for molecular pathways involved in inflammation and lung development in affected infants. Rare mutations in genes encoding the lipid transporter ATP-binding cassette, sub-family A, member 3 (ABCA3 gene) which is involved in surfactant synthesis in alveolar type II cells, as well as surfactant protein B (SFTPB) and C (SFTPC) can also result in severe form of neonatal-onset interstitial lung diseases and may also potentially affect the course of BPD. This chapter summarizes the current state of knowledge on the genetics of BPD.

Intrauterine Ureaplasma is associated with small airway obstruction in extremely preterm infants

BACKGROUND

The long-term follow-up of lung function (LF) in extremely preterm (EP) infants with bronchopulmonary dysplasia (BPD) has shown a worldwide increase in small airway obstructions (SAO).

OBJECTIVES

We investigated the relationships between intrauterine Ureplasma infection in EP infants and bubbly/cystic lung, BPD, and SAO at school age.

METHODS

Placental pathology, placental Ureaplasma DNA (pU-DNA), and cord blood immunoglobulin M (IgM) (C-IgM) were investigated in 360 EP infants born from 1981 to 2004. Maternal amniotic inflammatory response (M-AIR) scores and hemosiderin deposition (HD) were estimated in the chorioamnion. The study subjects were divided into groups based on their M-AIR scores. Their LF at school age was compared with those of 33 healthy siblings.

FINDINGS

pU-DNA and C-IgM were significantly related to SAO at school age (p < 0.012). M-AIR score 3 and pU-DNA >1000 units had an odds ratio (OR) of 35 (95% confidence interval: 10-172) and 18 (5.6-67) for bubbly/cystic lung, and 11 (3.1 - 43) and 31 (4.5-349) for severe BPD, and 5.3 (2.1-11) and 12 (2.4-74) for SAO, respectively. The ORs of surfactant treatment, BPD grade III, O₂ at 40 weeks, HD, and C-IgM >30 mg/dl for SAO were 0.21 (0.075-0.58), 5.3 (2.1-15), 2.5 (1.4-4.6), 3.6 (1.5-9.1) and 2.5 (1.0-5.2). 84% (90/107) SAO infants showed no or mild BPD in infancy, and 61% of infants had no severe CAM.

CONCLUSION

Our long-term cohort study of LF in EP infants revealed that intrauterine Ureaplasma was associated with bubbly/cystic lung, severe BPD, and SAO at school age.

Histological chorioamnionitis and its impact on respiratory outcome in very-low-birth-weight preterm infants

BACKGROUND

The role of intrauterine infection in the development of neonatal pulmonary disease is unclear and the impact of histological chorioamnionitis (HCAM) on respiratory outcomes in preterm infants remains controversial. The aim of this study was to explore the association between HCAM and neonatal respiratory outcomes in very-low-birth-weight (VLBW) preterm infants and evaluate the stepwise difference in the stage and severity of HCAM among neonatal respiratory outcomes.

METHODS

We retrospectively enrolled 129 VLBW preterm infants with placenta histopathology examinations in this study. HCAM was subdivided into 3 stages (early, intermediate, and advanced) according to the progression of the maternal inflammatory response. The perinatal characteristics, placental histopathology, and neonatal morbidities, including respiratory outcomes (respiratory distress syndrome (RDS), Wilson-Mikity syndrome (WMS) and bronchopulmonary dysplasia (BPD)), were collected for comparison.

RESULTS

A total of 52.7% (68/129) of the infants had HCAM, including 23 early (stage 1), 30 intermediate (stage 2), and 15 advanced (stage 3) stage. There was no significant difference in the gestational age, birth body weight or mortality rate between the HCAM and non-HCAM groups. Mothers with HCAM had a significantly lower incidence of pre-eclampsia but a higher rate of premature rupture of membrane. They also had higher WBC counts and C-reactive protein levels before delivery. Neonates with HCAM had a lower incidence of RDS but were at a higher risk for developing WMS and BPD. After multivariate analysis adjustment, HCAM was still negatively associated with RDS (aOR = .069, p < .001) but without correlation with BPD. However, neonates with intermediate to advanced-stage HCAM had a higher risk of developing WMS and increased home oxygen usage rate compared to those with early-stage HCAM.

CONCLUSION

HCAM has a protective effect from RDS in preterm neonates. Additionally, VLBW neonates with intermediate to advanced-stage HCAM are at risk for WMS.

Consider the lung as a sensory organ: A tip from pulmonary neuroendocrine cells

While the lung is commonly known for its gas exchange function, it is exposed to signals in the inhaled air and responds to them by collaborating with other systems including immune cells and the neural circuit. This important aspect of lung physiology led us to consider the lung as a sensory organ. Among different cell types within the lung that mediate this role, several recent studies have renewed attention on pulmonary neuroendocrine cells (PNECs). PNECs are a rare, innervated airway epithelial cell type that accounts for <1% of the lung epithelium population. They are enriched at airway branch points. Classical in vitro studies have shown that PNECs can respond to an array of aerosol stimuli such as hypoxia, hypercapnia and nicotine. Recent in vivo evidence suggests an essential role of PNECs at neuroimmunomodulatory sites of action, releasing neuropeptides, neurotransmitters and facilitating asthmatic responses to allergen. In addition, evidence supports that PNECs can function both as progenitor cells and progenitor niches following airway epithelial injury. Increases in PNECs have been documented in a large array of chronic lung diseases. They are also the cells-of-origin for small cell lung cancer. A better understanding of the specificity of their responses to distinct insults, their impact on normal lung function and their roles in the pathogenesis of pulmonary ailments will be the next challenge toward designing therapeutics targeting the neuroendocrine system in lung.

Pneumonia

The lung is constantly exposed to airborne infectious agents due to the large surface area of approximately 100 m². Therefore pneumonia is one of the most common lung diseases. Understanding infection requires understanding the routes of infections, the way invading organisms infect epithelial cells, as well as defense mechanisms of the lung tissue acquired during evolution.

 Different variants of infectious and non-infectious pneumonias are discussed; special types of pneumonias such as granulomatous and fibrosing pneumonias are presented under separate sections. Causing organisms and other causes of pneumonias are included, and their mode of action is included as far as understood.

Cystic Lung Disease in Down Syndrome: A Case Report and Literature Review

Subpleural lung cysts (SPC) are seen in children with Down syndrome (DS). The incidence and the long term course of these lesions are not known. It is important for pediatricians and pediatric radiologists to be aware of these lung lesions since the DS patients' longevity has increased and they have greater frequency to encounter the clinicians. Autopsy and the radiology series have shown that these lesions are often found in association with congenital heart disease, particularly the endocardial cushion defect and prematurity.

Bubbly and cystic appearance in chronic lung disease: Is this diagnosed as Wilson-Mikity syndrome?

Wilson-Mikity syndrome (WMS) was first reported in 1960 by Wilson and Mikity. They described preterm infants who developed areas of cystic emphysema in the first month of life with subsequent progression to chronic lung disease (CLD) of infancy, although these infants did not exhibit early respiratory distress, such as respiratory distress syndrome (RDS). This condition was widely accepted over the next 20 years, but WMS is now rarely mentioned and is commonly considered an anachronism. In Japan, CLD is classified into six types according to the presence of RDS and/or intrauterine inflammation and appearance on chest X-ray. One type of CLD (type III, which accounts for 13.5% of all CLD) is defined as history of intrauterine inflammation and the typical bubbly and cystic appearance on chest X-ray described in the original report of WMS. There is insufficient evidence to determine whether WMS exists or whether WMS is relatively common only in Japan and not in other countries. It is important, however, to distinguish this type of CLD from other types because the strategy for the prevention or treatment of CLD should be different according to its origin, cause, and risk factors.

Perinatal factors associated with long-term respiratory sequelae in extremely low birthweight infants

OBJECTIVE

To assess lung function at 8 years old in extremely low birthweight (ELBW) survivors and to identify perinatal determinants associated with impaired lung function.

DESIGN

Retrospective cohort study.

SETTING

Level III neonatal intensive care unit.

PATIENTS

ELBW survivors born in 1990-2004 with available spirometry at 8 years old were studied. Children were excluded if they had a Wechsler Intelligence Scale for Children Third Edition full IQ <70.

MAIN OUTCOME MEASURES

Multivariate logistic regression analysis was used to identify perinatal determinants associated with airway obstruction (forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) ratio <80%) at school age and the predictive power of potential determinants. Potential risk factors and predictors assessed in this study were gestational age, birth weight, small for gestational age, sex, chorioamnionitis, premature rupture of membranes, antenatal steroids, surfactant administration, respiratory distress syndrome, postnatal steroids, severe bronchopulmonary dysplasia and bubbly/cystic appearances of the lungs by X-ray during the neonatal period.

RESULTS

Of 656 ELBW survivors, 301 (45.9%) had attended a school-age follow-up at 8 years old. A total of 201 eligible children completed the lung function test. Bubbly/cystic appearance of the lungs (OR 4.84, 95% CI 1.26 to 18.70) was associated with a low FEV1/FVC ratio. Children with bubbly/cystic appearance had characteristics of immaturity and intrauterine inflammation.

CONCLUSIONS

Within a cohort of ELBW infants, a bubbly/cystic appearance of the lungs in the neonatal period was the strongest determinant of a low FEV1/FVC ratio at school age.

Diffuse Lung Disease

Diffuse lung disease (DLD) comprises a diverse group of disorders characterized by widespread pulmonary parenchymal pathology and impaired gas exchange. While many of these disorders are categorized under the rubric of interstitial lung disease (ILD), some of these disorders involve the airspaces or peripheral airways in addition to, or rather than, the interstitium. Some of these disorders are present primarily in infancy or early childhood, while others that are prevalent in adulthood rarely occur in childhood. This chapter will review the classification of pediatric DLD and the characteristic imaging findings of specific disorders to facilitate accurate diagnosis and guide appropriate treatment of children with these disorders.

The 'new' bronchopulmonary dysplasia: challenges and commentary

Lung development is orchestrated by highly integrated morphogenic programs of interrelated patterns of gene and protein expression. Injury to the developing lung in the canalicular and saccular phases of lung development alters subsequent alveolar and vascular development resulting in simplified alveolar structures, dysmorphic capillary configuration, variable interstitial cellularity and fibroproliferation that are characteristic of the 'new' bronchopulmonary dysplasia (BPD). Fetal and neonatal infection, abnormal stretch of the developing airways and alveoli, altered expression of surfactant proteins (or genetically altered proteins), polymorphisms of genes encoding for vascular endothelial growth factors, and reactive oxygen species result in imparied gas exchange in the developing lung. However, the 'new' BPD represents only one form of neonatal chronic lung disease and the consistent use of both the physiologic definition and severity scale would provide greater accuracy in determining the impact of the disease currently defined by its treatment. Our present labelling of the clinical state of oxygen supplementation and/or ventilatory support at 36 weeks' postmenstrual age and the histopathologic severity of alveolar arrest and vascular 'simplification' may not always be predictive of the degree of altered lung development and thus longer-term pulmonary function evaluations are needed to determine the impact of this disorder in specific infants. The proposed role of novel molecular therapies, and the combined effects of currently established therapies, as well as exogenous surfactant and inhaled nitric oxide or repetitive surfactant dosing, on the severity and incidence of new BPD hold considerable promise for reducing the long-term pulmonary morbidity among infants delivered prematurely.