title: Thyroid signaling in immune organs and cells of the teleost fish rainbow trout (Oncorhynchus mykiss).
abstract: Thyroid hormones are involved in modulating the immune system in mammals. In contrast, there is no information on the role played by these hormones in the immune system of teleost fish. Here we provide initial evidence for the presence of active thyroid signaling in immune organs and cells of teleosts. We demonstrate that immune organs (head kidney and spleen) and isolated leukocytes (from head kidney and peripheral blood) of the rainbow trout (Oncorhynchus mykiss) express both thyroid receptor α (THRA) and β (THRB). Absolute mRNA levels of THRA were significantly higher than those of THRB. THRA showed higher expression in immune organs and isolated immune cells compared to the reference organ, liver, while THRB showed the opposite. In vivo exposure of trout to triiodothryronine (T3) or the anti-thyroid agent propylthiouracil (PTU) altered THR expression in immune organs and cells. Effect of T3 and PTU over the relative expression of selected marker genes of immune cell subpopulations was also studied. Treatments changed the relative expression of markers of cytotoxic, helper and total T cells (cd4, cd8a, trb), B lymphocytes (mIgM) and macrophages (csf1r). These findings suggest that the immune system of rainbow trout is responsive to thyroid hormones.
authors.affiliation: Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Madrid, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Quesada-García
authors.affiliation: Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Madrid, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Valdehita
authors.affiliation: Centre for Fish and Wildlife Health, University of Bern, Switzerland.
authors.forename: C
authors.initials: C
authors.lastname: Kropf
authors.affiliation: Centre for Fish and Wildlife Health, University of Bern, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Casanova-Nakayama
authors.affiliation: Centre for Fish and Wildlife Health, University of Bern, Switzerland.
authors.forename: H
authors.initials: H
authors.lastname: Segner
authors.affiliation: Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Madrid, Spain. Electronic address: jmnavas@inia.es.
authors.forename: J M
authors.initials: JM
authors.lastname: Navas
mesh_terms: D000818:Animals; D005786:Gene Expression Regulation / Q000276:immunology; D060226:Head Kidney / Q000502:physiology*; D017686:Oncorhynchus mykiss / Q000502:physiology*; D011989:Receptors, Thyrotropin / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D013154:Spleen / Q000502:physiology*; D013961:Thyroid Gland / Q000502:physiology*
chemical_list: D011989:Receptors, Thyrotropin
keywords: Immune cell markers; Propylthiouracil; Rainbow trout; Thyroid receptors; Triiodothryronine