P079 Low-intensity Pulsed Ultrasound reflects the status of mucosal injury and repair through stage-specific miRNAs in experimental model of Ulcerative Colitis

Abstract Background Diagnosis and therapeutic efficacy monitoring of Ulcerative Colitis (UC) are based on a multidisciplinary approach comprising symptomatology and invasive endoscopic assessment coupled to the histopathological characterization of gut tissue biopsies. New technologies that non-invasively reflect tissue-specific changes remains an unmet need. Here we exploited Low Intensity Pulsed Ultrasound (LIPUS) to induce tissue stage-specific miRNAs in circulating blood as a non-invasive approach to reflect the status of the colonic mucosa in experimental model of colitis. Methods Based on our previous study, LIPUS was applied at a frequency of 38 kHz and at an intensity of 0 (as control) or 150 mW/cm2 for 3 min, using a device dedicated for in vivo studies. Acute and chronic colitis were induced in C57BL/6N mice (5 animals/group) by administration of 2 and 2.5% ad libitum dextran sodium sulfate (DSS) respectively in their drinking water for 7 days for the acute and three cycles of 7 days for the chronic model. miRNA array profiling was performed on extracellular vesicles (EVs) isolated from plasma of both acute and chronic models, at both active and remission state, 2 h after LIPUS stimulation. miRNA were correlated to the mucosal status by multiplexed immunofluorescence staining using Opal Multiplex IHC (CD4, CD8, CD68, pan-cytokeratin and CD31 markers) and EVs characterized by MACSplex surface epitope detection. Results An enrichment of EVs characterized mainly by stromal and immune cell surface markers was found in both acute and chronic inflammatory states, LIPUS stimulation significantly modulated miRNA profiles and clearly discriminated between active acute and chronic phases. 61 miRNAs in acute and 28 in chronic colitis were specifically and significantly upregulated by LIPUS in the active phase, with a fold change ranging from 2 to 1500 compared to control. Both acute and chronic disease showed a miRNA profile coherent with the active inflammatory state of intestinal mucosa. Only 10 and 23 miRNAs were upregulated in acute and chronic remission respectively. The enhancement of miR-18a-3p and miR-301b-3p in the recovery phases correlated to instetin with reduced immune cell infiltration and epithelial layer regeneration. Conclusion An optimal LIPUS dosage that non-invasively targets the colon induces the tissue to release specific miRNAs that reflect the mucosal status. LIPUS may open a new era of non-image ultrasound diagnostics that works as