Mo1728 Cytokine and microRNA Expression in Colonic and Ileal Crohn's Disease Is Modified by Drug Therapy in an Ex Vivo Model

Abstract

Introduction MicroRNAs (miRNA) are short 19–23 nucleotide long strands of RNA which modify post transcriptional gene expression by inhibiting mRNA translation. Studies show there is dysregulation of miRNA expression in IBD but do not take account of factors such as disease activity and drug treatment. The specific function of miRNAs in Crohns Disease (CD) or how they might be utilised is yet to be investigated. We aim to show that mucosal miRNA and mRNA expression in CD is influenced by drugs and has varying effects on the expression in ileum and sigmoid. We use an ex vivo model with active drug to replicate these changes. Method Sigmoid or ileal biopsies from 68 patients with either untreated active CD, inactive CD, or monotherapy with Azathioprine, Infliximab or Adalimumab, as well as normal controls, were snap frozen. RT-qPCR assessed expression of miR31, 155 and 146a and genes CCL18 and SOCS1. Ex vivo model: 6 biopsies were taken from the sigmoid colon of 8 patients with active sigmoid CD, and ileum of 7 patients with active ileal CD with a CDAI of 150 or greater. Biopsies were placed in culture media in separate wells with either no treatment, 5-ASA, 6-TG, Infliximab, or Adalimumab, then incubated at 37 o C. RT-qPCR analysed expression of miRNA and mRNA. Results miR31 and CCL18 expression was raised in active sigmoid CD compared to normal mucosa. miR31 expression was not raised in inactive sigmoid disease compared to normal mucosa, however CCL18 expression was. Only Azathioprine decreased miR31 expression. All treatments reduced CCL18 expression, but Azathioprine reduced it lower than untreated inactive disease. Ileal CD showed no increase of miR31 in active disease. CCL18 is reduced in ileal mucosa of CD compared to normal tissue. Only Adalimumab altered CCL18 expression in ileal CD. The ex vivo model showed all the treatments reduced CCL18 expression in active sigmoid CD. miR31 expression was reduced by 6-TG and Infliximab but not Adalimumab. In ileal CD drugs do not change miR31 or CCL18 expression, except for Adalimumab which increased CCL18 expression. Conclusion CCL18 and miR31 expression is only increased in sigmoid CD, suggesting different immunological pathways in ileal and colonic CD. Thiopurines are more effective at altering expression in colonic disease. Differential effects of anti-TNFs are of significant interest but require further investigation before any clinical significance can be made. Our data sheds new light on mechanisms of action of current therapy and highlights the importance of controlling for medication when analysing miRNA expression. For the first time we show expression profiles can be manipulated in an ex vivo model. This model could be useful in predicting individual treatment response. Disclosure of interest None Declared.