title: Low IL-8 is associated with anxiety in suicidal patients: genetic variation and decreased protein levels.
abstract: OBJECTIVE
  Recent studies indicate that inflammation may play a role in the pathophysiology of suicidality. Interleukin-8 (IL-8) is a chemokine that in addition to its function in the immune system also exert neuroprotective properties. The involvement of this chemokine in neuropsychiatric conditions is incompletely known.
  
  
  METHODS
  We measured plasma and cerebrospinal fluid (CSF) IL-8, as well as the genotype frequency of a single nucleotide polymorphism (-251A/T, rs4073) in the promoter region of the IL8 gene, in suicide attempters (n=206) and healthy controls (n=578).
  
  
  RESULTS
  Plasma and CSF levels of IL-8 were significantly lower in suicide attempters with anxiety than in healthy controls. IL-8 in both plasma and CSF correlated negatively with symptoms of anxiety. Compared with the population-based cohort, the IL-8-251T allele was more prevalent among female suicide attempters. Furthermore, suicide attempters carrying this allele showed more severe anxiety. This correlative study warrants further mechanistic studies on the effects of IL-8 in the central nervous system.
  
  
  CONCLUSIONS
  We suggest that IL-8 might be involved in the biological mechanisms mediating resilience to anxiety. Thus, our findings highlight the chemokine IL-8 as a potential target for future development of anti-anxiety treatments and suicide prevention.
authors.affiliation: Section for Psychiatry, Department of Clinical Sciences, Lund University, Lund, Sweden.
authors.forename: S
authors.initials: S
authors.lastname: Janelidze
authors.forename: P
authors.initials: P
authors.lastname: Suchankova
authors.forename: A
authors.initials: A
authors.lastname: Ekman
authors.forename: S
authors.initials: S
authors.lastname: Erhardt
authors.forename: C
authors.initials: C
authors.lastname: Sellgren
authors.forename: M
authors.initials: M
authors.lastname: Samuelsson
authors.forename: A
authors.initials: A
authors.lastname: Westrin
authors.forename: L
authors.initials: L
authors.lastname: Minthon
authors.forename: O
authors.initials: O
authors.lastname: Hansson
authors.forename: L
authors.initials: L
authors.lastname: Träskman-Bendz
authors.forename: L
authors.initials: L
authors.lastname: Brundin
mesh_terms: D000328:Adult; D001007:Anxiety / Q000097:blood / Q000134:cerebrospinal fluid / Q000235:genetics* / Q000378:metabolism*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D016209:Interleukin-8 / Q000097:blood / Q000134:cerebrospinal fluid / Q000235:genetics* / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide; D013405:Suicide / Q000523:psychology*
chemical_list: C508606:CXCL8 protein, human; D016209:Interleukin-8
keywords: biomarker; chemokine; depression; inflammation