title: Involvement of the histamine H4 receptor in clozapine-induced hematopoietic toxicity: Vulnerability under granulocytic differentiation of HL-60 cells.
abstract: Clozapine is an effective antipsychotic for treatment-resistant schizophrenia, but can cause fatal hematopoietic toxicity as agranulocytosis. To elucidate the mechanism of hematopoietic toxicity induced by clozapine, we developed an in vitro assay system using HL-60 cells, and investigated the effect on hematopoiesis. HL-60 cells were differentiated by all-trans retinoic acid (ATRA) into three states according to the following hematopoietic process: undifferentiated HL-60 cells, those undergoing granulocytic ATRA-differentiation, and ATRA-differentiated granulocytic cells. Hematopoietic toxicity was evaluated by analyzing cell survival, cell proliferation, granulocytic differentiation, apoptosis, and necrosis. In undifferentiated HL-60 cells and ATRA-differentiated granulocytic cells, both clozapine (50 and 100μM) and doxorubicin (0.2µM) decreased the cell survival rate, but olanzapine (1-100µM) did not. Under granulocytic differentiation for 5days, clozapine, even at a concentration of 25μM, decreased survival without affecting granulocytic differentiation, increased caspase activity, and caused apoptosis rather than necrosis. Histamine H4 receptor mRNA was expressed in HL-60 cells, whereas the expression decreased under granulocytic ATRA-differentiation little by little. Both thioperamide, a histamine H4 receptor antagonist, and DEVD-FMK, a caspase-3 inhibitor, exerted protection against clozapine-induced survival rate reduction, but not of live cell counts. 4-Methylhistamine, a histamine H4 receptor agonist, decreased the survival rate and live cell counts, as did clozapine. HL-60 cells under granulocytic differentiation are vulnerable under in vitro assay conditions to hematopoietic toxicity induced by clozapine. Histamine H4 receptor is involved in the development of clozapine-induced hematopoietic toxicity through apoptosis, and may be a potential target for preventing its occurrence through granulocytic differentiation.
authors.affiliation: Division of Clinical Sciences and Neuropsychopharmacology, Faculty and Graduate School of Pharmacy, Meijo University, 150 Yagotoyama, Tempaku-ku, Nagoya 468-8503, Japan.
authors.forename: Aya
authors.initials: A
authors.lastname: Goto
authors.affiliation: Division of Clinical Sciences and Neuropsychopharmacology, Faculty and Graduate School of Pharmacy, Meijo University, 150 Yagotoyama, Tempaku-ku, Nagoya 468-8503, Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Mouri
authors.affiliation: Division of Clinical Sciences and Neuropsychopharmacology, Faculty and Graduate School of Pharmacy, Meijo University, 150 Yagotoyama, Tempaku-ku, Nagoya 468-8503, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Nagai
authors.affiliation: Division of Clinical Sciences and Neuropsychopharmacology, Faculty and Graduate School of Pharmacy, Meijo University, 150 Yagotoyama, Tempaku-ku, Nagoya 468-8503, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Yoshimi
authors.affiliation: Division of Clinical Sciences and Neuropsychopharmacology, Faculty and Graduate School of Pharmacy, Meijo University, 150 Yagotoyama, Tempaku-ku, Nagoya 468-8503, Japan.
authors.forename: Mako
authors.initials: M
authors.lastname: Ukigai
authors.affiliation: Division of Clinical Sciences and Neuropsychopharmacology, Faculty and Graduate School of Pharmacy, Meijo University, 150 Yagotoyama, Tempaku-ku, Nagoya 468-8503, Japan.
authors.forename: Tomomi
authors.initials: T
authors.lastname: Tsubai
authors.affiliation: Division of Clinical Sciences and Neuropsychopharmacology, Faculty and Graduate School of Pharmacy, Meijo University, 150 Yagotoyama, Tempaku-ku, Nagoya 468-8503, Japan.
authors.forename: Hirotake
authors.initials: H
authors.lastname: Hida
authors.affiliation: Department of Psychiatry, Graduate School of Medicine, Nagoya University, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan.
authors.forename: Norio
authors.initials: N
authors.lastname: Ozaki
authors.affiliation: Division of Clinical Sciences and Neuropsychopharmacology, Faculty and Graduate School of Pharmacy, Meijo University, 150 Yagotoyama, Tempaku-ku, Nagoya 468-8503, Japan. Electronic address: ynoda@meijo-u.ac.jp.
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Noda
mesh_terms: D014150:Antipsychotic Agents / Q000633:toxicity*; D017209:Apoptosis / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects*; D003024:Clozapine / Q000633:toxicity*; D006098:Granulocytes / Q000187:drug effects* / Q000502:physiology; D018922:HL-60 Cells; D006633:Histamine Antagonists / Q000494:pharmacology; D006801:Humans; D008761:Methylhistamines / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D043562:Receptors, G-Protein-Coupled / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011968:Receptors, Histamine / Q000378:metabolism*; D000074040:Receptors, Histamine H4; D014212:Tretinoin / Q000494:pharmacology
chemical_list: D014150:Antipsychotic Agents; C418607:HRH4 protein, human; D006633:Histamine Antagonists; D008761:Methylhistamines; D010880:Piperidines; D043562:Receptors, G-Protein-Coupled; D011968:Receptors, Histamine; D000074040:Receptors, Histamine H4; C025566:4-methylhistamine; D014212:Tretinoin; C052075:thioperamide; D003024:Clozapine
keywords: Agranulocytosis; Apoptosis; Clozapine; HL-60 cells; Histamine H(4) receptor