title: NOD2 mutations affect muramyl dipeptide stimulation of human B lymphocytes and interact with other IBD-associated genes.
abstract: BACKGROUND
  Genetic and functional studies have associated variants in the NOD2/CARD15 gene with Crohn's disease.
  
  
  OBJECTIVE
  This study aims to replicate the association of three common NOD2 mutations with Crohn's disease, study its effect on NOD2 expression in B cells and its interaction with other IBD-associated genes.
  
  
  METHODS
  A total of 294 IBD patients (179 familial IBD, 115 sporadic IBD) and 298 unrelated healthy controls were from central Pennsylvania. NOD2 mutations were analyzed by primer-specific amplification, PCR based-RFLP, and validated with the ABI SNPlexM genotyping system. Gene-gene interaction was studied using a statistical model for epistasis analysis.
  
  
  RESULTS
  Three common NOD2 mutations are associated with Crohn's disease (p=5.08×10(-7), 1.67×10(-6), and 1.87×10(-2) for 1007fs, R720W, and G908R, respectively), but not with ulcerative colitis (p=0.1046, 0.1269, and 0.8929, respectively). For IBD overall, 1007finsC (p=4.4×10(-5)) and R720W (p=9.24×10(-5)) were associated with IBD, but not G908R (p=0.1198). We revealed significant interactions of NOD2 with other IBD susceptibility genes IL23R, DLG5, and OCTN1. We discovered that NOD2 was expressed in both normal human peripheral blood B cells and in EBV-transformed B cell lines. Moreover, we further demonstrated that muramyl dipeptide (MDP) stimulation of B lymphocytes up-regulated expression of NF-κB-p50 mRNA.
  
  
  CONCLUSIONS
  NOD2 is expressed in peripheral B cells, and the up-regulation of NOD2 expression by MDP was significantly impaired by NOD2 mutations. The finding suggests a possible role of NOD2 in the immunological response in IBD pathogenesis.
authors.affiliation: Division of Colon and Rectal Surgery, Department of Surgery, Pennsylvania State University College of Medicine, H137, 500 University Drive, Hershey, PA 17033, USA. zlin@hmc.psu.edu
authors.forename: Zhenwu
authors.initials: Z
authors.lastname: Lin
authors.forename: John P
authors.initials: JP
authors.lastname: Hegarty
authors.forename: Gerrit
authors.initials: G
authors.lastname: John
authors.forename: Arthur
authors.initials: A
authors.lastname: Berg
authors.forename: Zhong
authors.initials: Z
authors.lastname: Wang
authors.forename: Rishabh
authors.initials: R
authors.lastname: Sehgal
authors.forename: Danielle M
authors.initials: DM
authors.lastname: Pastor
authors.forename: Yunhua
authors.initials: Y
authors.lastname: Wang
authors.forename: Leonard R
authors.initials: LR
authors.lastname: Harris
authors.forename: Lisa S
authors.initials: LS
authors.lastname: Poritz
authors.forename: Stefan
authors.initials: S
authors.lastname: Schreiber
authors.forename: Walter A
authors.initials: WA
authors.lastname: Koltun
mesh_terms: D000119:Acetylmuramyl-Alanyl-Isoglutamine / Q000276:immunology*; D001402:B-Lymphocytes / Q000378:metabolism*; D016022:Case-Control Studies; D004843:Epistasis, Genetic; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000235:genetics* / Q000276:immunology; D008565:Membrane Proteins / Q000235:genetics; D009154:Mutation; D052002:NF-kappa B p50 Subunit / Q000378:metabolism; D053473:Nod2 Signaling Adaptor Protein / Q000235:genetics* / Q000502:physiology; D027701:Organic Cation Transport Proteins / Q000235:genetics; D018123:Receptors, Interleukin / Q000235:genetics; D027981:Symporters; D025521:Tumor Suppressor Proteins / Q000235:genetics; D015854:Up-Regulation
chemical_list: C114461:DLG5 protein, human; C515500:IL23R protein, human; D008565:Membrane Proteins; D052002:NF-kappa B p50 Subunit; C489548:NFKB1 protein, human; C429018:NOD2 protein, human; D053473:Nod2 Signaling Adaptor Protein; D027701:Organic Cation Transport Proteins; D018123:Receptors, Interleukin; C109807:SLC22A4 protein, human; D027981:Symporters; D025521:Tumor Suppressor Proteins; D000119:Acetylmuramyl-Alanyl-Isoglutamine