People with Crohn’s disease know the uncomfortable symptoms of the chronic condition all too well: diarrhea, abdominal pain, weight loss and fatigue, among others. But what doctors have not been able to tell the approximately 565,000 people in the U.S. with Crohn’s is why they’ve developed the inflammatory bowel condition in the first place. Most experts suspect the condition is the result of the body’s immune system attacking healthy cells, mistakenly triggered by bacteria in the digestive tract. Now, a new study has identified a specific fungus and two bacteria they think play a key role in what leads some people to develop the disease. “Among hundreds of bacterial and fungal species inhabiting the intestines, it is telling that the three we identified were so highly correlated in Crohn’s patients,” the study’s senior author Mahmoud A. Ghannoum, professor and director of the Center for Medical Mycology at Case Western Reserve and University Hospitals Cleveland Medical Center, said in a press release.
Bacteriome and Mycobiome Interactions Underscore Microbial Dysbiosis in Familial Crohn’s Disease
G. Hoaraua, P. K. Mukherjeeb, C. Gower-Rousseauc, C. Hagerb, J. Chandrab, M. A. Retuertob, C. Neuta, S. Vermeired, J. Clementee,f, J. F. Colombelc,g, H. Fujiokah, D. Poulaina, B. Sendida, M. A. Ghannoumb
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Crohn’s disease (CD) results from a complex interplay between host genetic factors and endogenous microbial communities. In the current study, we used Ion Torrent sequencing to characterize the gut bacterial microbiota (bacteriome) and fungal community (mycobiome) in patients with CD and their nondiseased first-degree relatives (NCDR) in 9 familial clusters living in northern France-Belgium and in healthy individuals from 4 families living in the same area (non-CD unrelated [NCDU]). Principal component, diversity, and abundance analyses were conducted, and CD-associated inter- and intrakingdom microbial correlations were determined. Significant microbial interactions were identified and validated using single- and mixed-species biofilms. CD and NCDR groups clustered together in the mycobiome but not in the bacteriome. Microbiotas of familial (CD and NCDR) samples were distinct from those of nonfamilial (NCDU) samples. The abundance of Serratia marcescens and Escherichia coli was elevated in CD patients, while that of beneficial bacteria was decreased. The abundance of the fungus Candida tropicalis was significantly higher in CD than in NCDR (P = 0.003) samples and positively correlated with levels of anti-Saccharomyces cerevisiae antibodies (ASCA). The abundance of C. tropicalis was positively correlated with S. marcescens and E. coli, suggesting that these organisms interact in the gut. The mass and thickness of triple-species (C. tropicalis plus S. marcescens plus E. coli) biofilm were significantly greater than those of single- and double-species biofilms. C. tropicalis biofilms comprised blastospores, while double- and triple-species biofilms were enriched in hyphae. S. marcescens used fimbriae to coaggregate or attach with C. tropicalis/E. coli, while E. coli was closely apposed with C. tropicalis. Specific interkingdom microbial interactions may be key determinants in CD.