title: A Gly15Arg mutation in the interleukin-10 gene reduces secretion of interleukin-10 in Crohn disease.
abstract: BACKGROUND
  Genetic susceptibility, probably involving cytokines and their receptors, plays an important role in inflammatory bowel disease (IBD). In this study we examine the potential role of the interleukin-10 (IL-10) gene as a susceptibility gene in IBD.
  
  
  METHODS
  We studied 17 sib-pairs with either Crohn disease (CD) or ulcerative colitis. After microsatellite analysis for allele-sharing, the IL-10 gene of sib-pairs who shared alleles was screened for nucleotide alterations in and around exons and the promoter region. The IL-10 promoter polymorphism at position -1082 was also determined. Function was evaluated by measuring IL-10 secretion by peripheral blood mononuclear cells stimulated with lipopolysaccharide or phorbol ester. The activity of recombinant immature wild-type and mutated IL-10 was tested in a proliferation assay with a human monocytic leukaemia cell line (HL60 cells).
  
  
  RESULTS
  DNA sequencing revealed a G --> A point mutation in exon 1 at base position 43 in one sib-pair, both affected with CD. It was also found in 2 of their healthy siblings, but not in 75 unrelated healthy controls. This mutation results in a glycine to arginine substitution at amino acid position 15 of the leader sequence (Gly15Arg). The in vitro IL-10 secretion by mononuclear cells of the IL-10 Gly15Arg carriers was about 50% of healthy controls, matched for the -1082 polymorphism in the IL-10 promoter region. Incubation of HL60 cells with recombinant mutated IL-10 showed a markedly reduced cell proliferation compared to wild-type IL-10.
  
  
  CONCLUSIONS
  A Gly15Arg mutation in the leader sequence of IL-10 was found in a multiple CD-affected family. This altered leader sequence decreases IL-10 secretion, thereby reducing the anti-inflammatory effect.
authors.affiliation: Dept. of Gastroenterology and Hepatology, Erasmus Medical Center Rotterdam, Rotterdam, The Netherlands.
authors.forename: K
authors.initials: K
authors.lastname: van der Linde
authors.forename: P P C
authors.initials: PP
authors.lastname: Boor
authors.forename: L A
authors.initials: LA
authors.lastname: Sandkuijl
authors.forename: M A C
authors.initials: MA
authors.lastname: Meijssen
authors.forename: H F J
authors.initials: HF
authors.lastname: Savelkoul
authors.forename: J H P
authors.initials: JH
authors.lastname: Wilson
authors.forename: F W M
authors.initials: FW
authors.lastname: de Rooij
mesh_terms: D000328:Adult; D001483:Base Sequence / Q000235:genetics; D003424:Crohn Disease / Q000235:genetics* / Q000276:immunology*; D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics; D006801:Humans; D016753:Interleukin-10 / Q000096:biosynthesis* / Q000235:genetics*; D007963:Leukocytes, Mononuclear / Q000276:immunology; D008297:Male; D018895:Microsatellite Repeats / Q000235:genetics; D008875:Middle Aged; D010375:Pedigree; D017354:Point Mutation
chemical_list: D016753:Interleukin-10