Background: Calprotectin (CP) faecal concentration is widely used as a non-invasive marker of inflammation of the intestinal mucosa, to assess the disease activity. In faecal samples, the abundance of Faecalibacterium prausnitzii (Fpra) and Fpra phylogroups (PGH-I and PHG-II), combined with Escherichia coli (Eco) seems to be an accurate biomarker to distinguish healthy (H) and diseased and also between disease locations according to a data also presented in this meeting by our group. The purpose of this study was to analyse the co-variation between these indicators and the disease activity in patients with CD and UC, and to determine its usefulness to discriminate between active and inactive disease.
Methods: A Spanish cohort consisting of 23 IBD (10 CD and 8 UC) and 12 H was enrolled. Sixty seven faecal samples (26 CD, 30 UC and 11 H) were obtained during treatment. Fpra, PHG-I, PHG-II and Eco abundances were determined by qPCR, and CP levels, using values above and below 250μg/g for active and inactive disease, respectively.
Results: The abundances of Fpra in CD and UC were lower in group CP >250μg/g compared to CP <250μg/g (p=0.024 and p=0.019, respectively). The abundance of PGH-II was lower in CD samples with CP >250μg/g (p=0.008), while PGH-I was less abundant in samples of active UC (p=0.002). No significant differences were found for Eco.
There was a significant inverse correlation between abundances of Fpra and the level of CP for both IBD (p=0.038 for CD and 0.035 for UC). CP was also inversely related to both, PHG-I and PHG-II in UC (p=0.013) and in CD (p=0.050), respectively.
Conclusions: The abundance of Fpra could be an accurate general discriminator of active disease, for IBD. In addition, PHG-I and PHG-II can be used as specific indicators of active disease in CD and UC, respectively.