P184 Identification of the PAI-1, as a potential non-invasive, fecal biomarker in the Inflammatory Bowel Diseases

Abstract

Abstract Background Inflammatory bowel diseases (IBD) are defined by unregulated immune response leading to intestinal inflammation. Monitoring of the intestinal inflammation are mostly invasive, time-consuming and expensive. Therefore, a simple, rapid and non-invasive test, with ability to differentiate IBD from other gastrointestinal conditions and to monitor disease activity and therapeutic response, will have important clinical implications. Our previous cytokine profiling identified that plasminogen activator inhibitor 1 (PAI-1) is expressed in IBD patients with active disease, but not in control. Therefore, our aim was to assess the utility of PAI-1 in monitoring disease activity and therapeutic response of IBD patients in different biological samples. Methods Biopsy, serum and fecal samples were collected from more than 150 active IBD patients and controls without IBD. Inclusion criteria included change of therapy or initiation of new treatment for IBD patients. Immunofluorescence (IF) staining was used to observe the presence and localisation of cytokines. Total protein and mRNA were isolated from biopsies and fecal samples. Protein levels were measured by ELISA and gene expression by qRT-PCR. Results The IF staining of the biopsy samples revealed a significantly higher percentage of PAI-1 positive cells in the inflamed mucosa compared to the control. The relative mRNA expression of PAI-1 was significant higher in non-responders and untreated, inflamed IBD patients compared to controls and responders. On the other hand, we were not able to detect significant changes between responders and non-responders in gene expression of TNF-α, IL-1β and IL-6. Serum, mucosal and fecal PAI-1 protein levels were significantly higher in IBD patients compared to controls. Whereas no significant difference was observed between Crohn’s disease and ulcerative colitis patients. The PAI-1 level was significant increased in endoscopically and clinically active disease compared to inactive patients and controls. In responders, PAI-1 concentration significantly decreased after initiation of therapy compared to non-responders. Significantly upregulated fecal PAI-1 level was found in active IBD compared to patients with inactive IBD, tumor, adenoma, diverticulosis and control. In addition, the stability analysis of fecal PAI-1 showed that the protein was detectable up to one week at room temperature and 4ºC. Conclusion Our findings suggest that serum, mucosal and fecal PAI-1 expression correlates with disease activity in IBD patients, suggesting that it could be utilized to monitor disease activity and possibly therapy response as a non-invasive biomarker in IBD.