Olle Björkqvist [1], Dirk Repsilber [1], Maike Seifert [2], Colin Brislawn [3], Janet Jansson [3], Lars Engstrand [2], Ignacio Rangel [1], Jonas Halfvarson [4]

Affiliates

1. School of Medical Sciences, Örebro University, Örebro, Sweden; 2. Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden; 3. Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington, USA 4. Department of Gastroenterology, Faculty of Medicine and Health, Örebro University, Örebro, Sweden.

Abstract

Background
Crohn’s disease is characterized by a dysbiosis with decreased abundance of specific butyrate producing taxa such as Faecalibacterium prausnitszii, but a causal relationship is yet to be established. In this study, we examined the relationship between temporal profiles of F. prausnitzii and of the C. leptum group, overall butyrate production of gut microbiota, and inflammatory activity in ileal Crohn’s disease.

Methods
Faecal samples (n=59) were collected every third month from nine patients with ileal Crohn’s disease. The relative abundance of F. prausnitzii and C. leptum was quantified relative to the total amount of bacteria using quantitative PCR (qPCR). To assess butyrate production of gut microbiota, gene copy numbers of the butyryl-CoA:acetate-CoA transferase (BCoAT) gene were quantified by qPCR. The inflammatory activity was defined by fecal (f-)calprotectin measurements.

Results
No correlation between the abundance of F. prausnitzii or the C. leptum group, copy numbers of the BCoAT gene, and f-calprotectin concentrations was observed in the total sample set. By analyzing alterations between consecutive samples, a negative correlation between the abundance of F. prausnitzii and f-calprotectin was observed (R=−0.39; p=0.009), but no significant correlation was observed for C. leptum (R=−0.18, p=0.23) or number of copies of the BCoAT gene (R=−0.12; p=0.42). The difference in abundance of F. prausnitzii between two consecutive samples accounted for 15% of the f-calprotectin variation.

Conclusions
There was an inverse correlation between temporal changes in the abundance of F. prausnitzii, but not butyrate production, and changes in inflammatory activity in ileal Crohn’s disease, indicating that F. prausnitzii may inhibit inflammation by non-butyrate dependent mechanisms.