Thématique :
Originalité :
Très original
Solidité :
Très solide
Doit faire évoluer notre pratique :
Pas encore
Nom du veilleur :
Professeur Philippe SEKSIK
Coup de coeur :
  2017 Aug;153(2):550-565.  
  doi: 10.1053/j.gastro.2017.05.010  
  Genetic Factors Interact With Tobacco Smoke to Modify Risk for Inflammatory Bowel Disease in Humans and Mice.  
  Yadav P, Ellinghaus D, Rémy G, Freitag-Wolf S, Cesaro A, Degenhardt F, Boucher G, Delacre M; International IBD Genetics Consortium, Peyrin-Biroulet L, Pichavant M, Rioux JD, Gosset P, Franke A, Schumm LP, Krawczak M, Chamaillard M, Dempfle A, Andersen V  



The role of tobacco smoke in the etiology of inflammatory bowel disease (IBD) is unclear. We investigated interactions between genes and smoking (gene-smoking interactions) that affect risk for Crohn's disease (CD) and ulcerative colitis (UC) in a case-only study of patients and in mouse models of IBD.


We used 55 Immunochip-wide datasets that included 19,735 IBD cases (10,856 CD cases and 8879 UC cases) of known smoking status. We performed 3 meta-analyses each for CD, UC, and IBD (CD and UC combined), comparing data for never vs ever smokers, never vs current smokers, and never vs former smokers. We studied the effects of exposure to cigarette smoke in Il10-/- and Nod2-/- mice, as well as in Balb/c mice without disruption of these genes (wild-type mice). Mice were exposed to the smoke of 5 cigarettes per day, 5 days a week, for 8 weeks, in a ventilated smoking chamber, or ambient air (controls). Intestines were collected and analyzed histologically and by reverse transcription polymerase chain reaction.


We identified 64 single nucleotide polymorphisms (SNPs) for which the association between the SNP and IBD were modified by smoking behavior (meta-analysis Wald test P < 5.0 × 10-5; heterogeneity Cochrane Q test P > .05). Twenty of these variants were located within the HLA region at 6p21. Analysis of classical HLA alleles (imputed from SNP genotypes) revealed an interaction with smoking. We replicated the interaction of a variant in NOD2 with current smoking in relation to the risk for CD (frameshift variant fs1007insC; rs5743293). We identified 2 variants in the same genomic region (rs2270368 and rs17221417) that interact with smoking in relation to CD risk. Approximately 45% of the SNPs that interact with smoking were in close vicinity (≤1 Mb) to SNPs previously associated with IBD; many were located near or within genes that regulate mucosal barrier function and immune tolerance. Smoking modified the disease risk of some variants in opposite directions for CD vs UC. Exposure of Interleukin 10 (il10)-deficient mice to cigarette smoke accelerated development of colitis and increased expression of interferon gamma in the small intestine compared to wild-type mice exposed to smoke. NOD2-deficient mice exposed to cigarette smoke developed ileitis, characterized by increased expression of interferon gamma, compared to wild-type mice exposed to smoke.


In an analysis of 55 Immunochip-wide datasets, we identified 64 SNPs whose association with risk for IBD is modified by tobacco smoking. Gene-smoking interactions were confirmed in mice with disruption of Il10 and Nod2-variants of these genes have been associated with risk for IBD. Our findings from mice and humans revealed that the effects of smoking on risk for IBD depend on genetic variants.


Question posée
Est-ce que les facteurs environnementaux tels que le tabac interagissent avec des facteurs génétiques au cours des MICI ?
Question posée
Oui. Ces résultats provenant d’analyses faites chez l’homme puis secondairement chez la souris montrent que le tabagisme modifie le risque de MICI associé à des variants génétiques spécifiques.

C’est l’une des premières études qui recherche ce type d’interaction et qui montre comment la génétique peut être révélée par un facteur d’environnement. A lire pour sa culture personnelle en passant le chapitre statistique (très ardu).