title: Hematopoietic stem and progenitor cell activation during chronic dermatitis provoked by constitutively active aryl-hydrocarbon receptor driven by Keratin 14 promoter.
abstract: Polycyclic aromatic hydrocarbons (PAHs) activate aryl-hydrocarbon receptor (AhR). Because PAHs are known as a risk factor for allergic diseases, PAH-induced AhR activation is expected to be involved in the development of the pathology. We previously generated transgenic mice expressing a constitutively active AhR (AhR-CA) under the control of Keratin 14 (K14) promoter (AhR-CA mouse). The mice develop chronic dermatitis with immune imbalance toward Th2 predominance, indicating that the AhR activation driven by K14 promoter provokes allergic response. Because hematopoietic cells actively participate in the development of allergic inflammation, it is important to understand the hematopoietic status under allergic conditions. To clarify how the K14 promoter-driven AhR activation influences hematopoiesis, we analyzed bone marrow and spleen of AhR-CA mice. We verified that AhR-CA was expressed in keratinocytes and thymic epithelial cells but not in hematopoietic cells. The AhR-CA mice with full-blown dermatitis exhibited leukocytosis and skewed differentiation of hematopoietic progenitor cells toward granulocyte-monocyte lineages. They also showed a significant expansion of short-term hematopoietic stem cells and multipotent progenitors and a subtle reduction in long-term hematopoietic stem cells (LT-HSCs). Their spleens were enlarged and abundantly accumulated hematopoietic stem and progenitor cells. AhR-CA mice at the early stage of dermatitis did not show leukocytosis or splenomegaly but exhibited the granulocyte-monocyte skewing and the reduction in LT-HSCs. Thus, AhR activation driven by K14 promoter already alters the hematopoietic differentiation and reduces LT-HSCs at the initial stage of dermatitis development. These results suggest that nonhematopoietic exposure to PAHs triggers allergic response and concomitantly affects hematopoiesis.
authors.affiliation: * Department of Medical Biochemistry, Tohoku University Graduate School of Medicine, Aoba-ku, Sendai, Miyagi 980-8575, Japan.
authors.forename: Shohei
authors.initials: S
authors.lastname: Murakami
authors.forename: Masayuki
authors.initials: M
authors.lastname: Yamamoto
authors.forename: Hozumi
authors.initials: H
authors.lastname: Motohashi
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000276:immunology; D002454:Cell Differentiation / Q000276:immunology; D002908:Chronic Disease; D003872:Dermatitis / Q000276:immunology* / Q000378:metabolism; D004195:Disease Models, Animal; D005260:Female; D005434:Flow Cytometry; D006098:Granulocytes / Q000166:cytology / Q000276:immunology; D006410:Hematopoiesis / Q000187:drug effects / Q000276:immunology*; D006412:Hematopoietic Stem Cells / Q000276:immunology* / Q000378:metabolism; D007150:Immunohistochemistry; D053547:Keratin-14 / Q000235:genetics*; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D009000:Monocytes / Q000166:cytology / Q000276:immunology; D011084:Polycyclic Aromatic Hydrocarbons / Q000633:toxicity; D011401:Promoter Regions, Genetic; D060888:Real-Time Polymerase Chain Reaction; D018336:Receptors, Aryl Hydrocarbon / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D013154:Spleen / Q000166:cytology / Q000276:immunology; D019076:Transgenes
chemical_list: D053547:Keratin-14; C507446:Krt14 protein, mouse; D011084:Polycyclic Aromatic Hydrocarbons; D018336:Receptors, Aryl Hydrocarbon
keywords: AhR; allergic inflammation; dermatitis.; hematopoiesis; hematopoietic stem cell