Mo1837 Inhibition of microRNA-29a in Human Bone Marrow Mesenchymal Stem Cells Increases Their Immunomodulatory Function

Abstract

The small intestine and colon differ greatly in both function and exposure to microbial products. Specific studies are needed to assess the response of microbial signaling in the small intestine versus the colon. Double-stranded RNAs (ds-RNA) are primarily viral products, but can also be derived from bacteria. Acute enteric viruses usually impact the small intestine, but viruses have also been investigated in inflammatory bowel disease and in post-infective irritable bowel syndrome and viruses are frequently found in colon cancer tissue. As such, understanding differences in the response of epithelial cells from the small intestine and colon to exposure to viral products will be important for dissecting the impact of infection at the different anatomical locations. Using newly developed culture techniques for growing primary enteroids and colonoids, we sought to compare the responses of enteroids versus colonoids to stimulation with the synthetic ds-RNA polyinosinic-polycytidylic acid (poly I:C). Murine crypts from jejunum or colon were plated in Matrigel for two days prior to the addition of poly I:C for the duration of culture. Stimulation of enteroids with poly I:C significantly altered the surface area but decreased the number of surviving enteroids compared to unstimulated. In colonoids, stimulation with poly I:C resulted in a significant decrease in bud count, but did not impact the area or survival of the organoids. Gene expression measured by the probe-based Nanostring technology in enteroids following poly I:C stimulation showed significantly decreased expression of stem cell markers including: Sox9, Lgr5, Dclk1, Tert and Lrig1. Additionally, differentiation markers Sis and Muc2 were significantly decreased. In contrast, fewer genes were significantly impacted by poly I:C stimulation in colonoids. Stem cell markers were not altered by poly I:C stimulation in colonoids. As expected, in both enteroids and colonoids inflammatory markers were significantly increased in response to poly I:C stimulation. Additionally, pro-apoptotic genes in both enteroids and colonoids were decreased following poly I:C stimulation. Comparing the response of enteroids and colonoids to poly I:C stimulation we found differences in the magnitude or direction of change in several classes of genes. These distinctions may derive frombaseline differences in expression levels. Enteroids had significantly increased expression of stem cell markers at baseline compared to colonoids, while colonoids had increased levels of inflammatory markers and toll-like receptors. Together, these data indicate that important functional differences exist between enteroids and colonoids at baseline and after viral product stimulation providing evidence which may help explain the different anatomical responses to viral infection throughout the intestinal tract.