title: PU.1 regulation of human alveolar macrophage differentiation requires granulocyte-macrophage colony-stimulating factor.
abstract: Granulocyte-macrophage colony-stimulating factor (GM-CSF) is critically implicated in lung homeostasis in the GM-CSF knockout mouse model. These animals develop an isolated lung lesion reminiscent of pulmonary alveolar proteinosis (PAP) seen in humans. The development of the adult form of human alveolar proteinosis is not due to the absence of a GM-CSF gene or receptor defect but to the development of an anti-GM-CSF autoimmunity. The role of GM-CSF in the development of PAP is unknown. Studies in the GM-CSF knockout mouse have shown that lack of PU.1 protein expression in alveolar macrophages is correlated with decreased maturation, differentiation, and surfactant catabolism. This study investigates PU.1 expression in vitro and in vivo in human PAP alveolar macrophages as well as the regulation of PU.1 by GM-CSF. We show for the first time that PU.1 mRNA expression in PAP bronchoalveolar lavage cells is deficient compared with healthy controls. PU.1-dependent terminal differentiation markers CD32 (FCgammaII), mannose receptor, and macrophage colony-stimulating factor receptor (M-CSFR) are decreased in PAP alveolar macrophages. In vitro studies demonstrate that exogenous GMCSF treatment upregulated PU.1 and M-CSFR gene expression in PAP alveolar macrophages. Finally, in vivo studies showed that PAP patients treated with GM-CSF therapy have higher levels of PU.1 and M-CSFR expression in alveolar macrophages compared with healthy control and PAP patients before GM-CSF therapy. These observations suggest that PU.1 is critical in the terminal differentiation of human alveolar macrophages.
authors.affiliation: Department of Pulmonary and Critical Care Medicine, The Cleveland Clinic Foundation, Cleveland, Ohio 44195-5038, USA.
authors.forename: Tracey L
authors.initials: TL
authors.lastname: Bonfield
authors.forename: Baisakhi
authors.initials: B
authors.lastname: Raychaudhuri
authors.forename: Anagha
authors.initials: A
authors.lastname: Malur
authors.forename: Susamma
authors.initials: S
authors.lastname: Abraham
authors.forename: Bruce C
authors.initials: BC
authors.lastname: Trapnell
authors.forename: Mani S
authors.initials: MS
authors.lastname: Kavuru
authors.forename: Mary Jane
authors.initials: MJ
authors.lastname: Thomassen
mesh_terms: D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D002454:Cell Differentiation / Q000502:physiology*; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000172:deficiency / Q000235:genetics / Q000627:therapeutic use; D006801:Humans; D016676:Macrophages, Alveolar / Q000166:cytology*; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000502:physiology*; D011649:Pulmonary Alveolar Proteinosis / Q000188:drug therapy / Q000235:genetics*; D011650:Pulmonary Alveoli / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics; D016186:Receptor, Macrophage Colony-Stimulating Factor / Q000235:genetics*; D011994:Recombinant Proteins; D012016:Reference Values; D015534:Trans-Activators / Q000235:genetics / Q000502:physiology*; D014158:Transcription, Genetic; D000099232:Proto-Oncogene Protein Spi-1
chemical_list: D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D016186:Receptor, Macrophage Colony-Stimulating Factor; D011994:Recombinant Proteins; D015534:Trans-Activators; D000099232:Proto-Oncogene Protein Spi-1