S178 Poster presentations Universitario de La Princesa, Department of Gastroenterology, IIS-IP and CIBERehd. Departamento de Medicina. Universidad Autónoma de Madrid., Madrid, Spain, 3 Hospital Universitario de La Princesa, Department of Gastroenterology, IIS-IP, Madrid, Spain, 4 Instituto de Biología y Genética Molecular IBGM, Mucosal Immunology Lab. Universidad de Valladolid-CSIC., Valladolid, Spain, 5 Both authors had equal contribution, as senior authors, Madrid, Spain Background: Plasma cells (PCs) and B lymphocytes (BLs) are a source of immunoglobulins (Ig), being IgA essential for intestinal homeostasis. An unbalanced intestinal Ig production has been described in infammatory bowel disease (IBD). Nevertheless little is known about the role of mucosal Ig-producing BL and PC in IBD, reason why we decided to study them. Methods: We included 12 healthy controls -HC-, 10 patients with ul- cerative colitis (three active -aUC- and seven quiescent -qUC) and 10 patients with Crohn’s disease (three active -aCD- and seven quiescent -qCD). Disease was located in the distal colon in all patients, although the quiescent ones had no infammation (endoscopic Mayo = 0; SES-CD = 0–1). Distal colon biopsies were collected together with per- ipheral blood. Mucus layer and epithelial barrier was removed from the biopsies and lamina propria mononuclear cells were harvested using the ‘walk-out’ protocol. Peripheral blood mononuclear cells were obtained after fcoll centrifugation. In both cases, cells were stained with specifc antibodies, acquired in a FACSCanto II cytometer, and analysed with FlowJo. Median percentage of PC and BL (and their subsets) relative to each tissue was calculated and compared using non-parametric statistics, considering statistically signifcant p < 0.05. Results: The proportion of plasmablasts, blood-precursors of PC, was higher in the blood of active IBD patients (HC: 0.8%; aUC: 5.3%; aCD: 3.4%). Even though there were no differences in the colonic proportion of PC between the study groups, there was a constitutive lower proportion of IgA-producing PC in IBD, irrespective of its type (UC or CD) or presence of infammation (HC: 88%; qUC: 55%; aUC: 38%; qCD: 70%; aCD: 44%). Moreover, aCD patients also showed a signifcantly higher proportion of IgM-producing PC (HC: 6% vs. aCD: 10%), and a higher proportion PC expressing CD19 compared both with HC and qCD (HC: 43%; qCD: 52%; aCD: 74%). The pro- portion of BL and their subsets did not show differences between the study groups, neither in blood nor in colon. However, in UC patients, some circulating subsets displayed a lower proportion of cells express- ing the gut-homing integrin β7: naive BL (HC: 11.5%; qUC: 2.9%; aUC: 0.6%) and IgM memory BL type CD27+ (HC: 43%; qUC: 30%; aUC: 23%) and also CD27- (HC: 32% vs. aUC: 5%). Conclusion: IBD patients have a diminished percentage of colonic IgA-producing PC, which is irrespective of the type of IBD or the infammatory status; this reduction could compromise the correct microbiota regulation in IBD. The reduction of the percentage of β7- expressing BL in the blood of UC patients could potentially point to a specifc pathogenic mechanism of UC. P087 Biomarkers of elastin degradation differentiate between clinically inactive and active disease in ulcerative colitis patients M. Pehrsson* 1 , V. Domislović 2 , M.A. Karsdal 1 , M. Brinar 2 , A. Barisic 3 , Z. Krznaric 2 , T. Manon-Jensen 1 , J.H. Mortensen 1 1 Nordic Bioscience A/S, Biomarkers and Research, Herlev, Denmark, 2 University Hospital Centre Zagreb, Department of Gastroenterology and Hepatology, Zagreb, Croatia, 3 University Hospital Centre Zagreb, Department for Clinical Nutrition, Zagreb, Croatia Background: In ulcerative colitis (UC), the state of chronic infammation results in increased matrix metalloprotease (MMP) and serine protease activity, which effectively leads to a higher degree of intestinal tissue remodelling, including components of the extracellular matrix (ECM). One of these components is elastin a matrix protein of the interstitial matrix in the lamina propria and submucosa, providing tissue resilience and elasticity. As such, we investigated whether elastin degradation in UC patients was associated with disease activity and severity, potentially enabling patient differentiation based on elastin degradation. Methods: Twenty-nine UC patients and 29 healthy donors were included in the study. Disease activity was determined according to the partial Mayo score (pMayo >1) and the Mayo Endoscopic Score (MES). Disease severity and extension was assessed using the Montreal classifcation. Disease severity was additionally assessed using the Trulove and Witt’s (TW) clinical score. The biomarkers of elastin degradation included: MMP-7 (ELM-7) cathepsin-G (EL- CG) and proteinase-3 (ELP-3), measured in serum by ELISA. One- way ANOVA (Kruskal–Wallis) correcting for the false discovery rate were applied for the statistical analysis. Results: TW: ELP-3 levels in moderate-to-severe UC patients were signifcantly elevated in comparison with HD (p < 0.001). Partial Mayo: EL-CG levels in patients with active UC were signifcantly elevated in comparison with HD (p < 0.01), and UC patients in re- mission (p < 0.01). ELP-3 levels were likewise signifcantly elevated in active UC patients compared with HD (p < 0.001), and UC patients in remission (p < 0.01). Montreal classifcation: ELM-7 was signifcantly elevated in active UC compared with HD (p < 0.05), and UC patients in remission (p < 0.05). EL-CG were also signif- cantly elevated in active UC compared with HD (p < 0.05), and UC patients in remission (p < 0.05). ELP-3 was signifcantly elevated in active UC compared with HD (p < 0.01). According to the MES score, ELP-3 levels in moderate-to-severe UC patients were signif- cantly elevated in comparison to HD (p < 0.01). Downloaded from https://academic.oup.com/ecco-jcc/article/14/Supplement_1/S178/5705344 by guest on 21 August 2022