P020 MAM, an anti-inflammatory protein derived from Faecalibacterium prausnitzii as a biomarker in Crohn’s disease?

Abstract

S140 Poster presentations could aid in tailoring drugs to individual patients. We therefore explored mucosal cytokine, chemokine and kinase activity profiles in IBD. Methods: Colonic mucosal biopsies were collected from (1) patients with Crohn's disease (CD, N = 8), (2) patients with ulcerative col-itis (UC, N = 8) and (3) healthy controls (N = 4). IBD samples were collected both from inflamed and non-inflamed tissue from the same patients. All IBD patients were biological-naïve and had not used corticosteroids in the past 3 months. Biopsies were snap frozen for later kinase activity determination or directly used in a 24-h explant culture. Whole biopsy kinase activity (tyrosine, serine and threo-nine kinases) was assessed using the Pamgene platform. A 64-ana-lyte panel was examined in the supernatant of the cultured biopsies employing a multiplex assay (Luminex). Results: Whole-biopsy kinase activity differed between inflamed and non-inflamed mucosa of IBD patients, with more overall tyrosine kinase activity in inflamed mucosa in UC, and serine/threonine kinase activity in inflamed mucosa in CD as compared with non-inflamed mucosa (Figure 1). The kinase activity profile of non-inflamed mu-cosa of CD and UC patients was similarly different from mucosa of healthy control participants (Figure 2). The cytokine and chemokine profile of inflamed biopsies differed from non-inflamed IBD biopsies and healthy control biopsies, with higher levels of S100A8, TNFα, IL-6, oncostatin M (OSM) and triggering receptor expressed on myeloid cells-1 (TREM-1), amongst others (Figure 3). Conclusion: In IBD, inflammation in the mucosa can be character-ised both by explant-culture and kinase activity assessment. The difference in kinase activity between non-inflamed IBD mucosa and healthy control mucosa suggests the presence of sub-clinical alterations in cell signalling. The observed differences in the kinase, cytokine and chemokine profiles underscore the importance of this approach in the elucidation of the pathophysiology in IBD. Background: The intestinal microbiota of patients with Crohn's disease (CD) is characterised by a specific dysbiosis, including the loss of Faecalibacterium prausnitzii (F. prau), a major bacterium with anti-inflammatory properties. MAM protein (microbiotia anti-inflammatory molecule) produced by F. prau has recently been identified as partially carrying the anti-inflammatory activity of this bacterium. The description of microbiota for diagnostic purposes in CD is currently difficult to achieve. MAM could be a biomarker of dysbiosis. Our goal was to study the expression of MAM in the intestinal ecosystem and to evaluate its interest as a biomarker. Methods: An in silico approach was used to determine primers of MAM gene sequences specific to two currently known phylogroups (I and II) of F. prau. Faecal samples were collected from a monocen-tric cohort of CD patients in flare (n = 24) and in remission (n = 24) and from healthy controls (n = 12). To measure MAM expression in vivo in the microbiota, we extracted total RNA and DNA from each sample and performed quantitative PCR (qPCR) with MAM primers (I and II), F. prau primers and universal bacterial primers. We compared the relative expression (ΔCt) of MAM mRNA and DNA with qPCR to the overall amount of bacteria in faecal samples.