title: Association of plasma IL-6 and soluble IL-6 receptor levels with the Asp358Ala polymorphism of the IL-6 receptor gene in schizophrenic patients.
abstract: Recent studies indicate a role of excessive interleukin-6 (IL-6) signaling in the pathogenesis of schizophrenia. A previous study reported a significant association of schizophrenia with the IL-6 receptor (IL-6R) gene Asp358Ala polymorphism, which is known to regulate circulating IL-6 and soluble IL-6R (sIL-6R) levels in healthy subjects. To further examine the influence of the polymorphism in schizophrenic patients, we compared the plasma levels of IL-6 and sIL-6R between schizophrenic patients and healthy controls for each genotype of the Asp358Ala polymorphism. Asp358Ala genotyping and plasma IL-6 level measurements were performed in 104 patients with schizophrenia and 112 healthy controls. Of these participants, 53 schizophrenic patients and 49 controls were selected for the measurement of plasma sIL-6R levels. A two-way factorial analysis of covariance was performed with the transformed plasma levels as the dependent variable, diagnosis and genotype as independent variables, and sex and age as covariates. No significant diagnosis × genotype interaction was observed for IL-6 and sIL-6R levels. The Ala allele of Asp358Ala was significantly associated with higher levels of both IL-6 and sIL-6R. IL-6 levels were significantly elevated in schizophrenic patients compared to those in controls, whereas no significant difference in sIL-6R levels was observed between schizophrenic patients and controls. Our findings suggest that the presence of schizophrenia is associated with elevated IL-6 levels, whereas sIL-6R levels are mainly predetermined by the Asp358Ala genotype and are not associated with the disease status. Increased IL-6 levels without alterations in sIL-6R levels may result in excessive IL-6 signaling in schizophrenia.
authors.affiliation: Department of Mental Disorder Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1 Ogawahigashi, Kodaira, Tokyo 187-8502, Japan.
authors.forename: Daimei
authors.initials: D
authors.lastname: Sasayama
authors.forename: Chisato
authors.initials: C
authors.lastname: Wakabayashi
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Hori
authors.forename: Toshiya
authors.initials: T
authors.lastname: Teraishi
authors.forename: Kotaro
authors.initials: K
authors.lastname: Hattori
authors.forename: Miho
authors.initials: M
authors.lastname: Ota
authors.forename: Masanori
authors.initials: M
authors.lastname: Ishikawa
authors.forename: Kunimasa
authors.initials: K
authors.lastname: Arima
authors.forename: Teruhiko
authors.initials: T
authors.lastname: Higuchi
authors.forename: Naoji
authors.initials: N
authors.lastname: Amano
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kunugi
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D005260:Female; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D015850:Interleukin-6 / Q000097:blood*; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic; D019947:Receptors, Interleukin-6 / Q000097:blood* / Q000235:genetics*; D012307:Risk Factors; D012559:Schizophrenia / Q000097:blood / Q000235:genetics* / Q000276:immunology*
chemical_list: D015850:Interleukin-6; D019947:Receptors, Interleukin-6