AUTHOR=Dubois-Camacho Karen , Diaz-Jimenez David , De la Fuente Marjorie , Quera Rodrigo , Simian Daniela , Martínez Maripaz , Landskron Glauben , Olivares-Morales Mauricio , Cidlowski John A. , Xu Xiaojiang , Gao Guangping , Xie Jun , Chnaiderman Jonás , Soto-Rifo Ricardo , González María-Julieta , Calixto Andrea , Hermoso Marcela A. 

TITLE=Inhibition of miR-378a-3p by Inflammation Enhances IL-33 Levels: A Novel Mechanism of Alarmin Modulation in Ulcerative Colitis

JOURNAL=Frontiers in Immunology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2019.02449

DOI=10.3389/fimmu.2019.02449

ISSN=1664-3224

ABSTRACT=<p>Ulcerative colitis (UC) is an inflammatory bowel disease (IBD) characterized by mucosa damage associated with an uncontrolled inflammatory response. This immunological impairment leads to altered inflammatory mediators such as IL-33, which is shown to increase in the mucosa of active UC (aUC) patients. MicroRNAs present a distorted feature in inflamed colonic mucosa and are potential IL-33 regulating candidates in UC. Therefore, we studied the microRNA and mRNA profiles in inflamed colonic samples of UC patients, evaluating the effect of a microRNA (selected by <italic>in silico</italic> analysis and its expression in UC patients), on IL-33 under inflammatory conditions. We found that inflamed mucosa (<italic>n</italic> = 8) showed increased expression of 40 microRNAs and 2,120 mRNAs, while 49 microRNAs and 1,734 mRNAs were decreased, as determined by microarrays. In particular, IL-33 mRNA showed a 3.8-fold increase and eight members of a microRNA family (miR-378), which targets IL-33 mRNA in the 3′UTR, were decreased (−3.9 to −3.0 times). We selected three members of the miR-378 family (miR-378a-3p, miR-422a, and miR-378c) according to background information and interaction energy analysis, for further correlation analyses with IL-33 expression through qPCR and ELISA, respectively. We determined that aUC (<italic>n</italic> = 24) showed high IL-33 levels, and decreased expression of miR-378a-3p and miR-422a compared to inactive UC (<italic>n</italic> = 10) and controls (<italic>n</italic> = 6). Moreover, both microRNAs were inversely correlated with IL-33 expression, while miR-378c does not show a significant difference. To evaluate the effect of TNFα on the studied microRNAs, aUC patients with anti-TNF therapy were compared to aUC receiving other treatments. The levels of miR-378a-3p and miR-378c were higher in aUC patients with anti-TNF. Based on these findings, we selected miR-378a-3p to exploring the molecular mechanism involved by <italic>in vitro</italic> assays, showing that over-expression of miR-378a-3p decreased the levels of an IL-33 target sequence β-gal-reporter gene in HEK293 cells. Stable miR-378a-3p over-expression/inhibition inversely modulated IL-33 content and altered viability of HT-29 cells. Additionally, in an inflammatory context, TNFα decreased miR-378a-3p levels in HT-29 cells enhancing IL-33 expression. Together, our results propose a regulatory mechanism of IL-33 expression exerted by miR-378a-3p in an inflammatory environment, contributing to the understanding of UC pathogenesis.</p>