Early indicators of chronic lung disease in preterm infants with respiratory distress syndrome and their inhibition by melatonin

Improved survival from advances in neonatal care has resulted in an increased number of infants at risk for chronic lung disease (CLD). Recently, it was reported that inflammatory mediators such as interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α and IL-8 are present in higher concentrations in lung lavage from babies who develop CLD. Previously, we found that melatonin reduced the rises in proinflammatory cytokines (IL-6, IL-8 and TNF-α) and nitrite/nitrate levels in the serum of preterm newborns with respiratory distress syndrome (RDS). The values correlated with gestational age and iatrogenic trauma in the form of oxygen exposure and mechanical ventilation. Increased concentrations of proinflammatory cytokines may, therefore, be the most valuable early indicator of developing CLD and these measurements may assist in selecting infants for interventions such as melatonin treatment or more selective blockage of components of inflammation. In the current study, we extend the original observations and report results in which 120 newborns diagnosed with RDS were either treated with melatonin (60 children) or given placebo (60 children). The cytokine measures were consistent with the previously reported findings and showed that melatonin reduced these values and also lowered nitrite/nitrate levels in serum of newborns with respiratory distress. Furthermore, when nonmelatonin-treated newborns who developed CLD (eight infants) were examined separately, they had levels of IL-6, IL-8, TNF-α and nitrite/nitrate values much higher than those in children who did not develop CLD. Two of the nonmelatonin-treated newborns died while no children who received melatonin died. Melatonin was well tolerated by the newborns.