Is There Any Correlation between Bronchopulmonary Dysplasia and IGF-1 Levels in Serum and Tracheal Aspirate Sample and Cytokine Levels in Tracheal Aspirate Sample?

Introduction: Bronchopulmonary dysplasia (BPD) is one of the most frequent causes of long-term morbidities in preterm infants. Many factors including prematurity, mechanical ventilation, oxygen therapy, or genetic factors play a role in the pathogenesis of BPD. Among these factors, antenatal infection and inflammation also play an important role. During the inflammatory process, which emerges as a result of different causes as prenatal, postnatal infection, mechanical ventilation, hypoxic injury, and hyperoxic damage many proinflammatory and anti-inflammatory cytokines play a role. Some studies have investigated the correlation between BPD and proinflammatory cytokines as interleukin (IL)-1, -6, -8, TNF-α, and anti-inflammatory cytokines as IL-10. Some studies have also demonstrated the potentially significant role of IGF-1, which involves pulmonary alveolarization and healing of tissue injuries, in the development of BPD. Lower levels of IGF-1 at birth have been shown to increase stepwise during the first 8 weeks of life, whereas others described an association between decrease in IGF-I levels during early postnatal period and development of BPD. Serum IGF-1 levels increase in line with gestational age; however, in infants who developed BPD, the IGF-1 levels do not increase. Also, in infants who develop BPD, serum IGF-1 levels are reported significantly lower when compared with those without BPD. In the light of these data, IGF-1 has been thought to play a role in the development of BPD by effecting alveolar angiogenesis especially through VEGF signalization. In this study, we aimed to assess the correlations between the development of BPD in premature infants, IGF-1 levels in serum, and tracheal aspirate (TA) and cytokine levels in TA measured at different time steps postnatally.

Materials and Methods: We enrolled premature infants born at ≤ 32 gestational weeks who were hospitalized and followed up in the NICU. On postnatal 1st, 3rd, 7th, 21st, and 28th days, serum IGF-1 levels and IL-6, IL-8, IL-10, and TNF-α levels in tracheal aspirate fluid samples of those infants being intubated were examined. Tracheal aspirate samples were collected during routine endotracheal suction on the first day of life.

Results: A total of 40 premature neonates were studied. Mean gestational age was 29.41 ± 2.23 weeks, and their mean birth weight was 1,256.85 ± 311.48 g. BPD was detected in 35% of cases. Mean gestational week and birth weight of the cases that developed BPD were 30 ± 3 weeks and 1,150 ± 295 g, respectively. Serum IGF-1 levels on postnatal 1st, 3rd, 7th, 21st, and 28th days in cases that developed BPD were found to be statistically significantly lower when compared with those without BPD (p  <  0.01). Levels of IL-6, IL-8, IL-10, and TNF-α in tracheal aspirate samples were significantly higher in cases with BPD than levels of cases without BPD (p  <  0.05), whereas IGF-1 levels in these samples did not differ statistically significantly based on the presence of BPD (p > 0.05).

Conclusion: According to our data, lower serum IGF-1 levels during the first month of life are associated with development and severity of BPD. In turn, such association is not detected as for what concerns tracheal aspirate levels. However, increased cytokine levels in tracheal aspirate samples are detected in preterm infants with BPD.

Keywords: bronchopulmonary dysplasia, IGF-1, cytokine, tracheal aspirate

 

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No conflict of interest has been declared by the author(s).