Macrophage migration inhibitory factor (MIF) -173G/C promoter polymorphism influences upper gastrointestinal tract involvement and disease activity in patients with Crohn's disease.
BACKGROUND
Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine with increased expression in inflammatory bowel disease. The aim of the study was to analyze the role of the MIF -173G/C single nucleotide polymorphism in Crohn's disease (CD).


METHODS
Using restriction fragment length polymorphism analysis, genomic DNA of 198 patients with CD and 159 unrelated controls was analyzed for the -173G/C SNP in the MIF promoter region. Colonic MIF mRNA expression was measured by quantitative polymerase chain reaction (PCR), serum MIF levels by enzyme-linked immunosorbent assay (ELISA).


RESULTS
Thirty-six of the 146 G/G wildtype carriers (24.7%) but only 3 of the 45 G/C heterozygotes (6.7%) and only 1 of the C/C homozygotes (14.3%) were diagnosed with upper gastrointestinal tract involvement (P = 0.009, odds ratio [OR] = 0.22, 95% confidence interval [CI], 0.06-0.75 for wildtype versus hetero- and homozygous carriers). This result was confirmed in a second prospective study, in which all patients diagnosed with upper gastrointestinal involvement (n = 13) were G/G wildtype carriers (P = 0.01 versus controls). All patients (n = 12; 100%) with a Crohn's disease activity index (CDAI) > 300 were G/G wildtype carriers compared to only 65.6% wildtype carriers in the group with a CDAI < 150 (P = 0.016). MIF is expressed in the colonic mucosa of CD patients and intestinal epithelial cells but its mRNA expression does not correlate with the degree of inflammation and is not upregulated by proinflammatory cytokines. In CD, MIF serum levels are not influenced by the MIF -173G/C polymorphism.


CONCLUSIONS
The MIF -173G/C polymorphism appears to be a factor contributing to a particular CD phenotype characterized by protection against upper gastrointestinal tract involvement and severe disease activity.
Dambacher
Julia
J
Department of Medicine II - Grosshadern, University of Munich, Munich, Germany.
Staudinger
Tanja
T
Seiderer
Julia
J
Sisic
Zeljka
Z
Schnitzler
Fabian
F
Pfennig
Simone
S
Hofbauer
Katrin
K
Konrad
Astrid
A
Tillack
Cornelia
C
Otte
Jan-Michel
JM
Diebold
Joachim
J
Göke
Burkhard
B
Ochsenkühn
Thomas
T
Lohse
Peter
P
Brand
Stephan
S
D000293:Adolescent; D000328:Adult; D003424:Crohn Disease / Q000235:genetics* / Q000473:pathology*; D005260:Female; D006801:Humans; D008263:Macrophage Migration-Inhibitory Factors / Q000235:genetics*; D008297:Male; D012150:Polymorphism, Restriction Fragment Length; D020641:Polymorphism, Single Nucleotide; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis; D041742:Upper Gastrointestinal Tract / Q000473:pathology*
D008263:Macrophage Migration-Inhibitory Factors; D012333:RNA, Messenger