Boochit Th eerasantipong1, Mana Taweevisit1, Paul Scott Th orner1,2
1Department of Pathology, Faculty of Medicine, Chulalongkorn University, 1873 King Rama IV Street, Pathumwan, Bangkok, 10330 Th ailand, 2Department of Pathology and Laboratory Medicine, Hospital for Sick Children and University of Toronto, Toronto M5G1X8, Canada
The pulmonary neuroendocrine system consists of pulmonary neuroendocrine cells (PNECs) and neuroendocrine bodies (NEBs) distributed throughout the respiratory epithelium which regulate lung growth and maturation in the antenatal period. Abnormalities in this system have been linked to many hypoxia-associated pediatric pulmonary disorders. Hemoglobin (Hb) Bart disease is a severe form of α- thalassemia. Affected fetuses suffer from marked intrauterine hypoxia with subsequent hydrops fetalis (HF) and die in utero or soon after delivery. Such fetuses can serve as a naturally occurring human model for the effects of intrauterine hypoxia and we postulated these effects should include changes in the pulmonary neuroendocrine system. In this investigation, Bombesin immunostaining was used to assess PNECs and NEBs in stillborn fetuses with Hb Bart HF (n =16) and HF by other causes (n =14) in comparison to non-HF, age-matched controls. Comparing Hb Bart HF to non-HF controls, there was a signiﬁ cant increase in the proportion of PNECs compared to respiratory epithelial cells (0.0129 vs. 0.0045, p= 0.002), mean number of NEB nuclei (3.9 vs. 3.4, p = 0.03), and mean size of NEBs (53.1 μm2 vs. 41.5 μm2, p= 0.002). Signiﬁ cant differences were not observed in HF due to other causes. The results indicate PNEC and NEB hyperplasia as well as NEB hypertrophy occurs in Hb Bart HF, presumably as an adaptive response to the hypoxic environment by enhancing differentiation from precursor cells and/or increased synthesis and storage of peptides. Hb Bart HF may provide a useful model for studying the pulmonary neuroendocrine system under chronic intrauterine hypoxic stress.