No association between the Clara cell secretory protein (CC16) gene polymorphism and personality traits Mamoru Tochigi a , Takeshi Otowa a , Hiroyuki Hibino a , Chieko Kato a , Tetsuya Marui a , Toshiyuki Ohtani a , Tadashi Umekage a,b , Nobumasa Kato a , Tsukasa Sasaki a,b, ⁎ a Department of Neuropsychiatry, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8655, Japan b Health Service Center, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8655, Japan Received 17 January 2006; received in revised form 4 April 2006; accepted 13 April 2006 Available online 9 June 2006 Abstract Clara cell secretory protein (CC16) is an anti-inflammatory protein expressed in the respiratory tract. Several studies have suggested the association between CC16 and mental disturbances, such as schizophrenia, depression, and post-traumatic stress disorder. In the present study, we investigated the association between the CC16 gene A38G polymorphism and personality traits in 214 healthy Japanese subjects. Personality traits were evaluated by using the Revised NEO Personality Inventory (NEO PI-R) and the State-Trait Anxiety Inventory (STAI). As a result, no significant association was observed between the genotypes and the scores of the NEO PI-R or the STAI. The present results suggest that CC16 may not have a major role in the development of personality traits. © 2006 Elsevier Inc. All rights reserved. Keywords: Clara cell secretory protein (CC16); Personality traits; The Revised NEO Personality Inventory (NEO PI-R); The State-Trait Anxiety Inventory (STAI) 1. Introduction A number of studies indicated that mental status could affect the immune system through lymphoid organs or neuroendocrine hormones (Marschall and Agarwal, 2000; Reiche et al., 2004). Individual difference of personality traits may have an important influence on immunity (Segerstrom, 2003). In addition, it has been suggested that the immune system may affect the pathophysiology of mental disturbances such as schizophrenia and affective disorders. Several cytokines, their receptors, or cytokine-related proteins were observed to increase in serum levels in patients with these diseases (Lin et al., 1998). Considering these associations, the components of the immune system may be one of the candidates which affect the development of personality traits. Clara cell secretory protein (CC16) is a 16-kD protein which plays a major role in the inflammatory response system. It is primarily expressed in the respiratory tract by nonciliated bronchiolar secretory cells (Hermans and Bernard, 1998) and has anti-inflammatory and immunosuppressive functions by acting as an anti-Th1-cytokine (Dierynck et al., 1995). The CC16 gene, located in the chromosome 11q13 region, has an A38G substitution, the A allele of which was observed to be associated with reduced plasma CC16 levels (Laing et al., 2000). The association between the polymorphism and asthma has been observed (Laing et al., 1998; Candelaria et al., 2005), although some studies did not replicate the association (Mansur et al., 2002). The association between CC16 and several mental dis- turbances has been suggested. The lowered serum CC16 have been suggested as a trait marker of schizophrenia and is likely related to the increased serum soluble interleukin-6 receptor (sLI-6R) (Maes et al., 1996; Lin et al., 1998; Altamura et al., 2003). The association between serum CC16 levels and depression, somatization syndrome, or post-traumatic stress disorder (PTSD) was also suggested (Maes et al., 1999; Rief et al., 2001). Hori et al. (2001) investigated the association between the A38G polymorphism of the CC16 gene and schizophrenia in a Japanese population, however, no significant association was observed. To our knowledge, no other study Progress in Neuro-Psychopharmacology & Biological Psychiatry 30 (2006) 1122 – 1124 www.elsevier.com/locate/pnpbp ⁎ Corresponding author. Department of Neuropsychiatry, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8655, Japan. Tel./fax: +81 3 5841 2588. E-mail address: psytokyo@yahoo.co.jp (T. Sasaki). 0278-5846/$ - see front matter © 2006 Elsevier Inc. All rights reserved. doi:10.1016/j.pnpbp.2006.04.019