title: Association of brain immune genes with social behavior of inbred mouse strains.
abstract: BACKGROUND
  Social deficit is one of the core symptoms of neuropsychiatric diseases, in which immune genes play an important role. Although a few immune genes have been shown to regulate social and emotional behaviors, how immune gene network(s) may jointly regulate sociability has not been investigated so far.
  
  
  METHODS
  To decipher the potential immune-mediated mechanisms underlying social behavior, we first studied the brain microarray data of eight inbred mouse strains with known variations in social behavior and retrieved the differentially expressed immune genes. We then made a protein-protein interaction analysis of them to find the major networks and explored the potential association of these genes with the behavior and brain morphology in the mouse phenome database. To validate the expression and function of the candidate immune genes, we selected the C57BL/6 J and DBA/2 J strains among the eight inbred strains, compared their social behaviors in resident-intruder and 3-chambered social tests and the mRNA levels of these genes, and analyzed the correlations of these genes with the social behaviors.
  
  
  RESULTS
  A group of immune genes were differentially expressed in the brains of these mouse strains. The representative C57BL/6 J and DBA/2 J strains displayed significant differences in social behaviors, DBA/2 J mice being less active in social dominance and social interaction than C57BL/6 J mice. The mRNA levels of H2-d1 in the prefrontal cortex, hippocampus, and hypothalamus and C1qb in the hippocampus of the DBA/2 J strain were significantly down-regulated as compared to those in the C57BL/6 J strain. In contrast, Polr3b in the hippocampus and Tnfsf13b in the prefrontal cortex of the DBA/2 J strain were up-regulated. Furthermore, C1qb, Cx3cl1, H2-d1, H2-k1, Polr3b, and Tnfsf13b were predicted to be associated with various behavioral and brain morphological features across the eight inbred strains. Importantly, the C1qb mRNA level was confirmed to be significantly correlated with the sociability in DBA/2 J but not in C57BL/6 J mice.
  
  
  CONCLUSIONS
  Our study provided evidence on the association of immune gene network(s) with the brain development and behavior in animals and revealed neurobiological functions of novel brain immune genes that may contribute to social deficiency in animal models of neuropsychiatric disorders.
authors.affiliation: Neuroscience Center, University of Helsinki, Viikinkaari 4, FIN-00014, Helsinki, Finland. li.ma@helsinki.fi.
authors.forename: Li
authors.initials: L
authors.lastname: Ma
authors.affiliation: Neuroscience Center, University of Helsinki, Viikinkaari 4, FIN-00014, Helsinki, Finland. sami.piirainen@helsinki.fi.
authors.forename: Sami
authors.initials: S
authors.lastname: Piirainen
authors.affiliation: Neuroscience Center, University of Helsinki, Viikinkaari 4, FIN-00014, Helsinki, Finland. natalia.kulesskaya@helsinki.fi.
authors.forename: Natalia
authors.initials: N
authors.lastname: Kulesskaya
authors.affiliation: Neuroscience Center, University of Helsinki, Viikinkaari 4, FIN-00014, Helsinki, Finland. heikki.rauvala@helsinki.fi.
authors.forename: Heikki
authors.initials: H
authors.lastname: Rauvala
authors.affiliation: Neuroscience Center, University of Helsinki, Viikinkaari 4, FIN-00014, Helsinki, Finland. li.tian@helsinki.fi.|Psychiatry Research Center, Beijing Huilongguan Hospital, Zhengfu Road, 100096, Beijing, Changping, China. li.tian@helsinki.fi.
authors.forename: Li
authors.initials: L
authors.lastname: Tian
mesh_terms: D000818:Animals; D053264:B-Cell Activating Factor / Q000235:genetics / Q000378:metabolism; D001921:Brain / Q000033:anatomy & histology / Q000378:metabolism*; D000073883:CX3C Chemokine Receptor 1; D016207:Cytokines / Q000235:genetics / Q000378:metabolism*; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000502:physiology*; D006183:H-2 Antigens / Q000235:genetics / Q000378:metabolism; D008297:Male; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D046228:Microarray Analysis; D009862:Online Systems; D012320:RNA Polymerase III / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D019707:Receptors, Chemokine / Q000235:genetics / Q000378:metabolism; D011951:Receptors, Complement / Q000235:genetics / Q000378:metabolism; D012919:Social Behavior; D013045:Species Specificity
chemical_list: D053264:B-Cell Activating Factor; D000073883:CX3C Chemokine Receptor 1; C471885:Cx3cr1 protein, mouse; D016207:Cytokines; D006183:H-2 Antigens; D008562:Membrane Glycoproteins; D012333:RNA, Messenger; D019707:Receptors, Chemokine; D011951:Receptors, Complement; C505720:Tnfsf13b protein, mouse; C032402:complement 1q receptor; D012320:RNA Polymerase III