Sphingolipid profile in tracheal aspirates as a new biomarker for the development of bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is the most common complication of premature
birth, affecting about 2000 premature born children in the Netherlands each
year. BPD is a chronic lung disorder with substantial long-term respiratory
consequences like impaired lung growth, decreased exercise tolerance and severe
obstructive airways disease, and also with neurological and cognitive
impairment. As a consequence, BPD has a substantial socio-economic impact.
Clinically BPD is defined as need for oxygen supplementation at 36 weeks
postmenstrual age (PMA). Pathologically BPD is characterized by disturbed lung
development with fewer and larger alveoli as a result of interrupted septation
and abnormal vascular organization. The molecular mechanisms underlying BPD are
largely unknown and currently the identification of useful biomarkers for BPD
development is an area of worldwide interest.
Sphingolipids are important structure-bearing constituents of the cell membrane
which also function as regulatory molecules of cell proliferation and cell
death, endothelial barrier function, angiogenesis, and immune response. Of the
sphingolipids, ceramides and sphingosine-1-phosphate determine the pro- and
anti-apoptotic balance, with ceramides stimulating apoptosis and cell cycle
arrest and sphingosine-1-phosphate stimulating cell survival and proliferation.
We recently observed transient increases of sphingolipid levels (including
ceramides) in a mice model of BPD and found that supplementation of
D-sphingosine during recovery after hyperoxia hastened normalisation of
ceramides and improved the hyperoxia-induced alveolar arrest in this animal
model of BPD. This finding suggested that sphingolipids play an essential role
in development of BPD, and might be used as a new biomarker of developing BPD.
Furthermore, based on our findings in the mouse model, sphingolipids seem a
promising target for an entirely new therapeutic strategy in BPD. The present
proposal aims to translate our recent findings in the mouse model to human BPD.

Primary Objective: To identify new markers in BPD, in particular in
sphingolipid- and oxylipin profiles in tracheal aspirates.

Secondary Objective(s): To predict the development of BPD in preterm infants by
the use of metabolomic analysis of the sphingolipid- and oxylipin profiles in
tracheal aspirates and to discover possible new targets for prevention and
therapeutic intervention in BPD.

Study design: Prospective, observational study.

The data will be collected at the neonatal intensive care unit, Erasmus MC -
Sophia Children*s Hospital. When premature born infants (<= 32 weeks of
gestation) are in need of invasive mechanical ventilation with an endotracheal
tube in the first week of life they are eligible for the study. We will obtain
tracheal aspirates directly after intubation and as long they are intubated at
consecutive days (1, 3, 5, 7 and 14). Tracheal aspirates will be obtained
during routine clinical suctioning procedures, and will be directly frozen and
stored at -80 degrees celcius. We will use mass spectrometry technique to
investigate the spingolipid- and oxylipin profiles. At day 28 after birth
children will be evaluated according to the old definition of BPD based on
their oxygen dependency. At 36 weeks postmenstrual age children will or will
not be diagnosed with BPD based on whether they have been oxygen dependent for
28 days or more. Furthermore, we will perform an oxygen reduction test in
order to define the severity of BPD (Figure 1 Flow chart in research proposal).
The duration of the study for each study subject will last from birth until 36
weeks postmenstrual age. We expect to need 1 year for including patients and
collecting all data.

This research is regarded as group-related because if you want to investigate
markers that might predict the development of BPD you need to investigate this
in a group who is still at risk to develop BPD. Therefore, we need to include
prematurely born children at risk for this disease. Infants participating in
this study will not get any direct benefits. There are no substantial risks
involved with participation.
When parents agree to let their prematurely born infant participate in this
study, tracheal aspirate samples will be collected during routine clinical
procedures. If sphingolipid profiles prove to be a reliable marker for the
development op BPD, we will become able to predict the development of BPD and
start early treatment. Furthermore, the sphingolipid pathway might be a new
target for future therapy.