7th Annual BMRP Investigator Meeting - Abstract

Identification of Target Antigens of Antibodies in Inflammatory Bowel Disease: Seroreactivity to Faecalibacterium prausnitzii and Bifidobacteria
 
Nathalie Vermeulen1,2, Marie Joossens2, Séverine Vermeire2,b, Paul Rutgeerts2 and Xavier Bossuyt1,a
 
1Departments of Laboratory Medicine and 2Internal Medicine, University Hospital Leuven (Belgium)
 
Crohn’s disease (CD) and ulcerative colitis (UC) are considered to originate from an aberrant immune response towards commensal bacteria in the gut in genetically predisposed patients. An imbalance of beneficial and detrimental commensal organisms, called dysbiosis, has been observed in IBD patients. Up to 80% of IBD patients show reactivity to bacterial components in their serum. A reduction of Faecalibacterium prausnitzii and Bifidobacteria has recently been reported in CD patients. We evaluated whether patients with IBD show seroreactivity to F. prausnitzii and Bifidobacteria.
 
Serum of 4 UC patients, 8 CD patients and 8 healthy controls was tested for reactivity against a protein extract from F. prausnitzii. No clear differences could be observed between the different groups, except for one prominent spot which was detected on western blots in 3 of 4 UC patients and in 6 of 8 CD patients. A very faint spot was observed in 1 of 8 healthy controls. We also examined DGGE profiles of fecal bacteria in 4 CD patients and 4 age and sex matched controls. We identified a band on DGGE gel as F. prausnitzii by sequencing. This band was present in feces of 3 of the 4 CD patients and in all healthy controls. Interestingly, the same patient who lacked the band corresponding to F. prausnitzii on DGGE also lacked the prominent spot on western blot analysis. Identification of this protein might allow one to understand why this bacterium exhibiting anti-inflammatory effects is found in reduced amounts in the feces of patients with IBD.
 
We started the same analysis for Bifidobacteria. So far, we screened 2 UC patients, 2 CD patients and 2 controls. We could not see a clear difference in seroreactivity against bifidobacteria between the different groups.
 
 
Sokol H, Pigneur B, Watterlot L, Lakhdari O, Bermúdez-Humarán LG, Gratadoux JJ, Blugeon S, Bridonneau C, Furet JP, Corthier G, Grangette C, Vasquez N, Pochart P, Trugnan G, Thomas G, Blottière HM, Doré J, Marteau P, Seksik P, Langella P. Faecalibacterium prausnitzii is an anti-inflammatory commensal bacterium identified by gut microbiota analysis of Crohn disease patients. Proc Natl Acad Sci U S A. 2008 Oct 28;105(43):16731-6.
  
aPrincipal Investigator; bCo-Investigator and Presenter