title: Cytokine gene polymorphism in microscopic colitis association with the IL-6-174 GG genotype.
abstract: OBJECTIVE
  Microscopic colitis (MC) is a chronic inflammatory disease with unknown pathogenesis. Very little is known about polymorphisms in the cytokine genes in MC. We have investigated the occurrence of well-characterized polymorphisms of interleukins (IL-6, IL-1β, IL-1 receptor antagonist, IL-10) and CD14 in MC. We also determined the serum IL-6 levels.
  
  
  METHODS
  We genotyped 81 patients with MC and 178 controls for polymorphisms of IL-6-174, IL-1β-511, IL-1β-3953, IL-1 receptor antagonist, IL-10-1082 and CD14-159. Serum concentration of IL-6 was measured in 72 patients.
  
  
  RESULTS
  Genotype GG of IL-6-174 was more prevalent in MC compared with the controls (P=0.030; odds ratio: 1.941; confidence interval: 1.078-3.495), and the frequency of allele G of IL-6-174 was higher in MC (0.55 vs. 0.47; P=0.036; odds ratio: 1.514; confidence interval: 1.041-2.203). However, after correction for multiple comparisons, the difference became nonsignificant. IL-6 genotype and the serum IL-6 concentration showed no association. The concentration of IL-6 was higher in patients with collagenous colitis than in those with lymphocytic colitis (median 1.73 vs. 1.34 pg/ml, P=0.011). No association between polymorphisms of other cytokine genes and MC was seen.
  
  
  CONCLUSIONS
  The IL-6-174 gene polymorphism has a possible association with MC, as the IL-6 GG genotype was more frequent in patients with the disease. As this genotype may be linked with an enhanced IL-6 production, we speculate that this polymorphism can influence the pathogenesis of MC by evoking a proinflammatory bias in the mucosal cytokines. The enhanced concentration of IL-6 in collagenous colitis compared with lymphocytic colitis supports a difference in the pathogenetic mechanisms between the two subgroups of MC.
authors.affiliation: Department of Internal Medicine, Gastroenterologic Unit, Oulu University Hospital, Kajaanintie 50, Oulu, Finland. ritva.koskela@oulu.fi
authors.forename: Ritva M
authors.initials: RM
authors.lastname: Koskela
authors.forename: Tuomo J
authors.initials: TJ
authors.lastname: Karttunen
authors.forename: Seppo E
authors.initials: SE
authors.lastname: Niemelä
authors.forename: Juhani K
authors.initials: JK
authors.lastname: Lehtola
authors.forename: Risto S
authors.initials: RS
authors.lastname: Bloigu
authors.forename: Riitta A
authors.initials: RA
authors.lastname: Karttunen
mesh_terms: D046728:Colitis, Microscopic / Q000235:genetics* / Q000276:immunology; D016207:Cytokines / Q000235:genetics* / Q000276:immunology; D005260:Female; D005787:Gene Frequency; D006801:Humans; D015850:Interleukin-6 / Q000097:blood / Q000235:genetics* / Q000276:immunology; D018950:Lipopolysaccharide Receptors / Q000235:genetics / Q000276:immunology; D008297:Male; D011110:Polymorphism, Genetic; D011446:Prospective Studies; D012737:Sex Factors
chemical_list: D016207:Cytokines; D015850:Interleukin-6; D018950:Lipopolysaccharide Receptors