Abnormal Fecal Microbiota in Healthy Subjects at High Risk for Crohn's Disease

Study Overview
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Brief Summary
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Transversal multicentric French study on the microbiota in patients with Crohn's disease and their first degree healthy relatives The primary objective is the comparison of microbiota between patients with CD, healthy controls non genetically linked and first degree healthy relatives of patients with CD.

Detailed Description
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Crohn's disease is a chronic inflammatory bowel disease associating flares and remission periods. Its etiology is unknown and there are no specific therapy. CD affects young patients and has a major impact on quality of life. There are few population-based studies and there are about 2.5 million affected patients in Europe and North America. From data from EPIMAD Registry the number of affected patients in France should be 200 000. The Crohn's disease pathogenesis is bad known; It coul be the results of the activation of the gastro-intestinal immune system toward gut microbiota in genetically susceptible hosts. In CD patients there is an important ecologic modification of the flora with an excess of Bacteroidetes and Proteobacteria and a decrease of anti inflammatory bacteria (Firmicutes). In ileum of CD patients a specific E Coli (adherent and invasive E Colo) is found in two thirds of cases.The presence of this AIEC seems to be associated to the variant NOD2 (results from our team in multiplex families). In a family with at least 1 patient with CD, the healthy first degree relatives present a high risk (* 10) to also develop a CD. The primary objective is the comparison of microbiota between patients with CD, healthy controls non genetically linked and first degree healthy relatives of patients with CD. The first endpoint is the Lachnospiraceae rates in each group. The secondary objectives are : the search for an association between bacterial dysbiosis and different genetic backgrounds in patients with CD, their first degree healthy relatives and controls. the quantification of potential invasive bacteria with invasive properties (E. coli including adherent-invasive E. coli, Shigella, Salmonella, Yersinia, Campylobacter), and fecal fungal flora (Candida albicans, in particular) and their association with genetic and serological profiles in patients with CD, their healthy relatives and control subjects. a study of environmental risk factors using a questionnaire to be submitted to CD patients, their healthy relatives and control subjects.

Official Title
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Evidence of Abnormal Fecal Microbiota in Healthy Subjects at High Risk for Crohn's Disease: Family Studies and Relations With a Particular Genetic Profile and Serological. Comparison of Affected Individuals, Their Siblings and Healthy Controls.

Conditions
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Crohn's Disease, Genetic Predisposition

Intervention / Treatment
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* Other: biomarkers


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patient with Crohn's disease Patient > 18 years old Having at least one first degree health relative OK to participate to the project First degree healthy relatives specific clinical questionnaire and dosing fecal calprotectin to ensure the absence of inflammatory pathology. OK to participate to the project Exclusion Criteria: Intestinal resection. Pregnant or breastfeeding woman. subject under guardianship subject does not speak French person unable to speak taking antibiotics or bowel preparation will push 6 weeks stool specimens, after cessation treatments.

Ages Eligible for Study
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Minimum Age: 8 Years
Maximum Age: 50 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| case Crohn disease<br>60 cases with Crohn's Disease | Other: biomarkers<br>* fecal microbiota analysis antibodies in serum and saliva DNA polymorphisms<br>* Other names: Dysbiosis;|
| first relative healthy<br>2 healthy relatives per CD case (total 120) | Other: biomarkers<br>* fecal microbiota analysis antibodies in serum and saliva DNA polymorphisms<br>* Other names: Dysbiosis;|
| controls<br>60 controls matched on gender and age with CD cases | Other: biomarkers<br>* fecal microbiota analysis antibodies in serum and saliva DNA polymorphisms<br>* Other names: Dysbiosis;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Percentage of Lachnospiraceae bacteria in stools within 3 groups | After extraction DNA, microbiota will be studied via study of ribosomal DNA 16S using quantitative PCR and pyroséquençage | 1 YEAR | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Number of bacteria Firmicutes phylum (including Faecalibacterium prausnitzii and Clostridium Leptum) in stools within 3 groups | After extraction DNA, microbiota will be studied via study of ribosomal DNA 16S using quantitative PCR and pyroséquençage | 1 year | 
| Define different genetic and serologic backgrounds within 3 groups | Genetic analysis will include 380 genetic variants génétiques that will be genotyped including classic variants involved in CD: variants or mutations of NOD2, NOD1, IL23R, ATG16L1, DGL5, TNF, IL6, NFKB1... genes. Serological analysis will included anti-OmpC, anti-I2 and ASCA auto antibodies. | 1 year | 
| Quantify of bacteria with invasive properties (including AIEC) within 3 groups | Amplify bacterial DNA of Salmonella Typhi (amplification of ITS area specific of ARNr 16S-23S gene. For AIEC, using of qPCR methods based on chuA and yjaA genes. | 1 year | 
| Study of environmental risk factors within 3 groups | Specific questionnaire on environmental risk factors including vaccination, antibiotic use, ionfections, Home facilities and Diet befor the CD diagnosis | 1 year | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Crohn's Disease, Healthy relatives, Dysbiosis, Biomarkers