Estudio de la regulación post-transcripcional de genes mediada por micro-RNA en pacientes con colitis ulcerosa tratados con glucocorticoides

Abstract

Background: Ulcerative colitis (UC) is a chronic inflammatory bowel disease of unknown etiology. Glucocorticoids (GC) remain the first-line treatment for moderate and severe active disease. However, 40% of patients do not have an appropriate response. We do not know yet the exact underlying mechanism associated with bad response and we are not able to predict it. The utility of molecules like microRNA (miRNA) in the prediction of response to treatments is a reality in other fields of medicine, for example in oncology, but little is known about the utility of these molecules in Inflammatory Bowel Disease. This thesis pretends to delve into refractoriness to GC by studying transcriptome of colonic tissue of patients with ulcerative colitis flares. Objectives: The main objective was to confirm the presence of different colonic transcriptome profiles associated to inadequate response to systemic GC in patients with moderate and severe flares of UC. Secondary objectives were to characterize the immediate effect of systemic GC treatment on the colonic transcriptome, and to determine the mechanism of action related to adequate and inadequate response. Material and Methods: Colic tissue samples of patients with moderate and severe flares of CU were collected before starting GC, and on the 3rd day of treatment. Patients were grouped in responder (less than moderate activity without need for rescue at day 7 of GC) and non-responder (moderate or severe activity at day 7 of GC). In adition, colic tissue samples from healthy controls were collected. Samples were studied by sequencing methods for miR profiles (TruSeq Small RNA Sample kit Illumina), and with microarrays (Human HT-12 kit v4.0 Expression BeadChip Illumina) for hold transcriptome study. Results of each group were compared. Subsequently bioinformatics was used to integrate results and to generate a theoretical model of response to the drug. Results: 10 controls and 24 patients with moderate or severe of UC flares treated with GC were included (13 responders and 11 non-responders to GC). The integrity of samples allowed experimental study in 10 patients of each group and 6 healthy controls. The sequencing results showed a differential miR profile (miR-625-3p, miR-196b-3p) at baseline between responders and non-responders. The comparison between responders before and after treatment show 6 differential miR (miR-183-5p, miR-584-5p, miR-126-5p, miR-625-3p, miR-1271-5p; miR -409-5p), and one differential RNAm (DDIT4 / REDD1). The comparison between non responders before and after GC treatment show 13 differential miR between groups (miR-200c-3p, miR-18a-5p; miR-192-5p, miR-183-5p, miR-200a-5p; miR 10a-5p; miR-545-5p, miR-132-5p, miR-194-5p, miR-625-3p, miR-1271-5p, miR-409-5p, miR-504-5p). In silico study suggests a possible association of the mTOR signaling pathway with the response to glucocorticoids in patients with UC flares and this pathway was used to generate 2 different models of response to GC. Conclusions: This study shows that there is a different profile in the colonic tissue transcriptome of patients with moderate or severe flares of UC responders and non-responders to systemic GC before starting treatment. This colonic transcriptome change with treatment and those changes were different in responders and non-responders. There may be an association between the regulation of the mTOR pathway by miR and the response to GC in UC.

Date of Award	10 Nov 2016
Original language	Spanish
Awarding Institution	Universitat Autònoma
Supervisor	Eugeni Domenech Morral (Director), Eduard Cabre Gelada (Director) & Josep Mañé Almero (Director)