P-201 Neurotensin-HIF-1α-microRNA-210 Axis Orchestrates Hypoxia, Colonic Inflammation and Intestinal Angiogenesis

Abstract

Tissue oxygenation is critical in intestinal inflammation, due to its unique steady state profile in the gut. During gut inflammation, hypoxic conditions activate hypoxia-inducible factor 1α (HIF-1Α), increasing miR-210 expression levels. On the other hand, expression of the neuropeptide neurotensin (NT) and tis cognate receptor 1 (NTR1) are increased during gut inflammation. We have previously elucidated the miRNA expression signature of NT signaling in human colonic NCM460 epithelial cells overexpressing NTR1. MiR-210 was one of the most strongly up-regulated miRNAs in response to NT. Our aim was to elucidate NT-initiated pathways that may affect colitis via NTR1-HIF-1-miR-210 interactions, relative to inflammation and angiogenesis. NCM40-NTR1 and human intestinal microvascular endothelial cells (HIMEC) individually or in co-culture were exposed to NT, in the presence or absence of the NTR1 inhibitor SR48692 to assess hypoxia pathway activation and tube formation. In vivo angiogenesis was assessed in colitic WT and NTR1-knockout mice. The role of miR-210 was assessed in vivo by intracolonic administration of locked nucleic acid miR-210 (LNA-miR-210). We report that NT/NTR1 signaling induces stabilization, activation, nuclear translocation and transcriptional activity of HIF-1α in NCM460-NTR1s. Moreover, we report pro-angiogenic effects of NT signaling both in vitro and in vivo. Importantly, in vivo silencing of miR-210 via intracolonic administration of LNA-as-miR-210 significantly reduces mouse colon miR-210 expression and attenuates colitis. Our results link NTR1 with hypoxia in relation of the latter to proinflammatory signaling. Moreover, we report a novel association between miRNA expression and intestinal angiogenesis.