title: Hyperplasia and hypertrophy of pulmonary neuroepithelial bodies, presumed airway hypoxia sensors, in hypoxia-inducible factor prolyl hydroxylase-deficient mice.
abstract: Pulmonary neuroepithelial bodies (NEBs), presumed polymodal airway sensors, consist of innervated clusters of amine (serotonin) and peptide-producing cells. While NEB responses to acute hypoxia are mediated by a membrane-bound O2sensor complex, responses to sustained and/or chronic hypoxia involve a prolyl hydroxylase (PHD)-hypoxia-inducible factor-dependent mechanism. We have previously reported hyperplasia of NEBs in the lungs ofPhd1-/- mice associated with enhanced serotonin secretion. Here we use a novel multilabel immunofluorescence method to assess NEB distribution, frequency, and size, together with the number and size of NEB cell nuclei, and to colocalize multiple cytoplasmic and nuclear epitopes in the lungs ofPhd1-/-,Phd2+/-, andPhd3-/- mice and compare them with wild-type controls. To define the mechanisms of NEB cell hyperplasia, we used antibodies against Mash1 and Prox1 (neurogenic genes involved in NEB cell differentiation/maturation), hypoxia-inducible factor-1alpha, and the cell proliferation marker Ki67. Morphometric analysis of (% total lung area) immunostaining for synaptophysin (% synaptophysin), a cytoplasmic marker of NEB cells, was significantly increased inPhd1-/- andPhd3-/- mice compared to wild-type mice. In addition, NEB size and the number and size of NEB nuclei were also significantly increased, indicating that deficiency ofPhds is associated with striking hyperplasia and hypertrophy of NEBs. InPhd2+/- mice, while mean % synaptophysin was comparable to wild-type controls, the NEB size was moderately increased, suggesting an effect even in heterozygotes. NEBs in allPhd-deficient mice showed increased expression of Mash1, Prox1, Ki67, and hypoxia-inducible factor-1alpha, in keeping with enhanced differentiation from precursor cells and a minor component of cell proliferation. Since the loss of PHD activity mimics chronic hypoxia, our data provide critical information on the potential role of PHDs in the pathobiology and mechanisms of NEB cell hyperplasia that is relevant to a number of pediatric lung disorders.
authors: Division of Pathology, Department of Pediatric Laboratory Medicine, The Research Institute, The Hospital for Sick Children; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada.
authors: Jie
authors: J
authors: Pan
authors: Nuffield Department of Medicine, Henry Wellcome Building for Molecular Physiology, University of Oxford, Oxford, UK.
authors: Tammie
authors: T
authors: Bishop
authors: Nuffield Department of Medicine, Henry Wellcome Building for Molecular Physiology, University of Oxford, Oxford, UK.
authors: Peter J
authors: PJ
authors: Ratcliffe
authors: Division of Pathology, Department of Pediatric Laboratory Medicine, The Research Institute, The Hospital for Sick Children; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada.
authors: Herman
authors: H
authors: Yeger
authors: Division of Pathology, Department of Pediatric Laboratory Medicine, The Research Institute, The Hospital for Sick Children; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada.
authors: Ernest
authors: E
authors: Cutz
keywords: HIF; Mash1; PHD; hypoxia; neuroendocrine; pulmonary