title: Chronic allergen challenge induces pulmonary extramedullary hematopoiesis.
abstract: Allergic inflammation is associated with increased generation and trafficking of inflammatory cells, especially eosinophils, to sites of inflammation. The effect of acute versus chronic airway allergen challenge on hematopoietic activity in the bone marrow (BM) and lungs was investigated using murine models of allergic airway inflammation. Acute allergen challenge induced proliferation of BM cells and significantly increased generation of eosinophil, but not multipotent, granulocyte-macrophage (GM), or B-lymphocyte progenitor cells. However, no hematopoietic activity was observed in the lungs. With chronic challenge, BM cells failed to proliferate, but exhibited increased capacity to generate multipotent as well as eosinophil, GM, and B-lymphocyte progenitors. In addition, increased generation of eosinophil- and GM-specific progenitors was observed in the lungs. Although no differences were observed in their ability to roll on BM endothelium in vitro or in vivo, CD34-enriched hematopoietic/stem progenitor cells (HSPCs) from chronic-, but not acute-, challenged mice demonstrated reduced migration across BM endothelial cells associated with decreased CXCR4 expression. Overall, these studies demonstrate that chronic allergen exposure can alter BM homing due to decreased transendothelial migration enabling noninteracting HSPCs to egress out of the BM and recruit to sites of inflammation such as the airways, resulting in extramedullary hematopoiesis.
authors.affiliation: Laboratory of Allergic Diseases and Inflammation, Department of Veterinary and Biomedical Sciences, University of Minnesota, St. Paul, Minnesota 55108, USA.
authors.forename: Terlika S
authors.initials: TS
authors.lastname: Pandit
authors.forename: M Reza
authors.initials: MR
authors.lastname: Hosseinkhani
authors.forename: Bit Na
authors.initials: BN
authors.lastname: Kang
authors.forename: Nooshin S
authors.initials: NS
authors.lastname: Bahaie
authors.forename: Xiao Na
authors.initials: XN
authors.lastname: Ge
authors.forename: Savita P
authors.initials: SP
authors.lastname: Rao
authors.forename: P
authors.initials: P
authors.lastname: Sriramarao
mesh_terms: D000485:Allergens / Q000008:administration & dosage / Q000276:immunology*; D000818:Animals; D018952:Antigens, CD34 / Q000276:immunology; D002460:Cell Line; D002465:Cell Movement / Q000276:immunology; D004802:Eosinophilia / Q000276:immunology / Q000378:metabolism; D004804:Eosinophils / Q000276:immunology / Q000378:metabolism; D006411:Hematopoiesis, Extramedullary / Q000276:immunology*; D007249:Inflammation / Q000276:immunology* / Q000378:metabolism; D008168:Lung / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D039902:Multipotent Stem Cells / Q000276:immunology / Q000378:metabolism; D023461:Myeloid Progenitor Cells / Q000276:immunology / Q000378:metabolism; D054448:Precursor Cells, B-Lymphoid / Q000276:immunology / Q000378:metabolism; D019718:Receptors, CXCR4 / Q000378:metabolism
chemical_list: D000485:Allergens; D018952:Antigens, CD34; C514936:CXCR4 protein, mouse; D019718:Receptors, CXCR4