P148 COLONIC SPROUTY2 IS ELEVATED IN INFLAMMATORY BOWEL DISEASE PATIENTS

Background The intestinal epithelium plays a central role in protecting against the development of colitis, and is disrupted in inflammatory bowel disease (IBD). It serves as the physical barrier that, when breached, allows luminal contents (i.e. bacteria, antigens) to stimulate inflammatory responses. Sprouty2 (SPRY2) is an intracellular regulator of growth factor receptor signaling that is downregulated in a compensatory response to inflammatory stimuli in cell lines and a mouse model of colitis. Additionally, mice with intestine-specific Spry2 deletion are protected against colitis and have elevated tuft and goblet cell numbers, cell types thought to protect the intestinal epithelium. This may represent a feedback mechanism to reinforce the intestinal epithelium during the initial stages of injury. However, the regulation of SPRY2 in IBD patients is unknown. We hypothesized that SPRY2 expression might be dysregulated in patients with IBD. Methods SPRY2 levels were measured by quantitative PCR analysis of human colonic tissue from endoscopic biopsies and surgical resection specimens from pediatric IBD and non-IBD patients. Human colonoids (primary cultures of colonic epithelium) were grown from surgical resection specimens of non-IBD control patients. SPRY2 expression was measured via qPCR in response to treatment with TNF for 24 hrs. Results SPRY2 expression decreased by an average of 24.41% (p = 0.0002, n =4) in colonoids from non-IBD patients treated with tumor necrosis factor (TNF) 10 ng/mL and 18.13% (p = 0.0016) for 100 ng/mL. However, SPRY2 expression in endoscopic biopsies from IBD patients was 2.325 ± 0.9846 fold higher in ulcerative colitis (UC) patients (p= 0.0242, n =8) and 9.825 ± 2.800 fold higher in Crohn’s disease patients (p= 0.0014, n=6) compared to non-IBD controls (n=27). In surgical specimens, SPRY2 levels were 37.10 ± 21.96 (p= 0.0459) fold higher in IBD (n=6) vs. non-IBD (n=4) patients. Furthermore, data mining of Gene Expression Omnibus dataset GDS3268 (biopsies from UC patients) revealed a significant negative correlation between SPRY2 and the protective tuft cell markers DCLK1 and TRPM5. Conclusion Acute TNF signaling repressed SPRY2 expression in a human colonoid model. In contrast, SPRY2 levels appear to be increased in human IBD and negatively correlate with tuft cell markers. Together these data suggest that, while acute inflammation can downregulate SPRY2 to drive increased numbers of protective secretory cells, in chronic disease this response either does not occur or is lost. A failure to down-regulate SPRY2 in response to early mucosal damage may be a factor in the development of IBD.