Fecal microbiota composition of CD patients and their relatives clarified
MedWire News: Patients with Crohn's disease (CD) have a different fecal microbiota composition from that of healthy controls, say researchers who also found that unaffected relatives of CD patients had their own distinct intestinal flora.
The team found that the fecal microbiota of CD patients was characterized by a decrease in Dialister invisus, an uncharacterized species of Clostridium cluster XIVa, Faecalibacterium prausnitzii, and Bifidobacterium adolescentis, and an increase in Ruminococcus gnavus characterized compared with that of healthy controls.
"This dysbiosis signature was markedly characteristic for the disease as it was not observed in unaffected relatives despite a common genetic background and shared nutritional habits," write Séverine Vermeire (University Hospital Gasthuisberg, Leuven, Belgium) and team.
Writing in the journal Gut, Vermeire and colleagues describe the results of their study in which fecal samples were taken from 68 patients with CD, 84 unaffected relatives (with at least three family members with CD), and 55 controls who did not have CD or CD affected relatives. Denaturing gradient gel electrophoresis (DGGE) was used to identify colonizing microbial species.
Interestingly, although the unaffected relatives and the CD patients did not have the same fecal microbiota composition, both groups had a different pattern to that of the healthy controls.
The unaffected relatives had fecal microbiota characterized by lower levels of Collinsella aerofaciens and a member of the Escherichia coli-Shigella group, and a higher level of Ruminococcus torques than healthy controls.
"In contrast to CD-associated dysbiosis, the dysbiosis in relatives of patients was not characterized by a lack of butyrate-producing capacity, but similar enhanced mucin degradation could be hypothesized," say the authors.
"As the mucosal barrier is the first-line defense of the host against intestinal bacteria, the shift from normobiosis to the dysbiosis observed in relatives of patients with CD might be an intermediate step towards CD and disease-associated dysbiosis."
They conclude: "Further investigation should reveal not only if the balance between butyrate production and mucin degradation is indeed essential in predisposing to CD but also how this balance can be influenced."
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By Helen Albert