Intestinal DMBT1 expression is modulated by Crohn's disease-associated IL23R variants and by a DMBT1 variant which influences binding of the transcription factors CREB1 and ATF-2.
OBJECTIVE
DMBT is an antibacterial pattern recognition and scavenger receptor. In this study, we analyzed the role of DMBT1 single nucleotide polymorphisms (SNPs) regarding inflammatory bowel disease (IBD) susceptibility and examined their functional impact on transcription factor binding and downstream gene expression.


METHODS
Seven SNPs in the DMBT1 gene region were analyzed in 2073 individuals including 818 Crohn's disease (CD) patients and 972 healthy controls in two independent case-control panels. Comprehensive epistasis analyses for the known CD susceptibility genes NOD2, IL23R and IL27 were performed. The influence of IL23R variants on DMBT1 expression was analyzed. Functional analysis included siRNA transfection, quantitative PCR, western blot, electrophoretic mobility shift and luciferase assays.


RESULTS
IL-22 induces DMBT1 protein expression in intestinal epithelial cells dependent on STAT3, ATF-2 and CREB1. IL-22 expression-modulating, CD risk-associated IL23R variants influence DMBT1 expression in CD patients and DMBT1 levels are increased in the inflamed intestinal mucosa of CD patients. Several DMBT1 SNPs were associated with CD susceptibility. SNP rs2981804 was most strongly associated with CD in the combined panel (p = 3.0 × 10(-7), OR 1.42; 95% CI 1.24-1.63). All haplotype groups tested showed highly significant associations with CD (including omnibus P-values as low as 6.1 × 10(-18)). The most strongly CD risk-associated, non-coding DMBT1 SNP rs2981804 modifies the DNA binding sites for the transcription factors CREB1 and ATF-2 and the respective genomic region comprising rs2981804 is able to act as a transcriptional regulator in vitro. Intestinal DMBT1 expression is decreased in CD patients carrying the rs2981804 CD risk allele.


CONCLUSIONS
We identified novel associations of DMBT1 variants with CD susceptibility and discovered a novel functional role of rs2981804 in regulating DMBT1 expression. Our data suggest an important role of DMBT1 in CD pathogenesis.
Department of Medicine II - Grosshadern, Ludwig-Maximilians-University (LMU), Munich, Germany ; Department of Preventive Dentistry and Periodontology, Ludwig-Maximilians-University (LMU), Munich, Germany.
Julia
J
Diegelmann
Darina
D
Czamara
Emmanuelle
E
Le Bras
Eva
E
Zimmermann
Torsten
T
Olszak
Andrea
A
Bedynek
Burkhard
B
Göke
Andre
A
Franke
Jürgen
J
Glas
Stephan
S
Brand
D051698:Activating Transcription Factor 2 / Q000378:metabolism*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001483:Base Sequence; D001665:Binding Sites; D002135:Calcium-Binding Proteins; D016022:Case-Control Studies; D003424:Crohn Disease / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism*; D004268:DNA-Binding Proteins; D004843:Epistasis, Genetic; D005260:Female; D056726:Genetic Association Studies; D020022:Genetic Predisposition to Disease; D006801:Humans; D007378:Interleukins / Q000502:physiology; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011956:Receptors, Cell Surface / Q000235:genetics* / Q000378:metabolism; D018123:Receptors, Interleukin / Q000235:genetics*; D017422:Sequence Analysis, DNA; D015533:Transcriptional Activation; D025521:Tumor Suppressor Proteins; D055815:Young Adult; D000097043:Interleukin-22
D051698:Activating Transcription Factor 2; D002135:Calcium-Binding Proteins; D017362:Cyclic AMP Response Element-Binding Protein; D004268:DNA-Binding Proteins; D007378:Interleukins; D011956:Receptors, Cell Surface; D018123:Receptors, Interleukin; D025521:Tumor Suppressor Proteins; D000097043:Interleukin-22; C497105:ATF2 protein, human; C115163:CREB1 protein, human; C108174:DMBT1 protein, human; C515500:IL23R protein, human