Sirtuin1 in tracheal aspirate leukocytes: possible role in the development of bronchopulmonary dysplasia in premature infants

Objective: To study the association between Sirtuin1 (Sirt1), a class III histone deacetylator, in tracheal aspirate (TA) leukocytes and the development of bronchopulmonary dysplasia (BPD) in premature infants and modulation of Sirt1 with dexamethasone (Dex) use. Design/methods: Serial TA samples were collected on days 1, 3, 5 and 7 from ventilated premature neonates. Sirt1 was localized by immunocytochemistry and quantified on a scale of 0-4 by blinded observers. BPD was defined as the need of supplemental oxygen at 36 weeks postmenstrual age (PMA). Results: A total of 130 TA samples were collected from 51 infants (mean +/- SD: GA 25.5 +/- 1.4 w, BW 762 +/- 174 g). Eleven infants survived without BPD and 40 infants died before 36 weeks PMA or developed BPD. Sirt1 was localized in the cytoplasm and nuclei of mononuclear (MONO) as well as polymorphonuclear cells. Sirt1 was significantly more localized in the nuclei of MONO cells in infants without BPD compared to infants who developed BPD or died before 36 weeks PMA. Twenty six infants received Dex. There was no significant change in Sirt1 localization with steroid therapy. Conclusions: Lower Sirt1 in TA leukocytes is associated with the development of BPD or death in premature infants. Dex use had no effect on Sirt1.