Novel Hydrogen Peroxide (H2O2) Sensing Probe for In Vivo Cellular Imaging in Colorectal Cancer

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stem cell number may select for optimal mutation spectra and influence gastrointestinal tumor distribution Methods: Wnt target gene activity in individual small intestinal and colonic whole mount crypts was assessed using qRT-PCR. Stem cell number was counted using in-situ hybridization for Lgr5. The regional intestinal effect of increased Wnt signaling was examined in the mouse using a stabilized beta catenin transgenic model (Villin-CreERT2; Catnb lox(ex3)/lox(ex3)) and the human by comparing upper gastrointestinal (UGI) and colonic APC mutation spectra in FAP and sporadic CRC patients. Results: Wnt target gene activity and stem cell number were greatest in the proximal small intestine (SI) decreasing steadily through to the colon. The BMP2 gradient was inversely correlated. The stabilized beta catenin transgenic mice had a striking phenotype with lesion distribution mirroring this gradient - thus the proximal SI was carpeted with dysplastic lesions, whereas the colon was polyp free. However stem cell number was increased in the transgenic mouse colon. Human FAP associated UGI APC mutations retained more beta-catenin binding 20 aminoacid repeats (AAR) than the same patient's colonic lesions. Sporadic CRC lesion distribution tended to vary according to the number of 20AAR's retained with left sided lesions requiring fewer 20AAR's than right sided. Conclusion: The ‘just right’ hypothesis proposes a threshold of wnt signaling should be reached but not exceeded in order for polyp formation to occur. We have demonstrated a physiological SI to colonic gradient of wnt signal and stem cell number. Thus the wnt signal threshold gap varies throughout the intestinal tract. Betacatenin stabilization in the mouse provides sufficient wnt signal perturbation to initiate tumour formation in the small intestine but is insufficient to initiate dysplasia in the colon, despite increasing the number of intestinal stem cells. The physiological wnt gradient determines the distribution of sporadic and polyposis-associated tumours by selecting for the optimal mutation spectra in each lesion- thus left sided lesions select for common mutations that provide a greater wnt perturbation than their more proximal counterparts.

AGA Abstracts

Weight Loss in Obesity Reduces Colorectal Inflammation With Upregulation of FOXP3 Regulatory T Cells Swaroop Pendyala, Michaela M. Ennis, Judilyn Fuentes-Duculan, Peter R. Holt Introduction: In obesity, adipose tissue shows evidence of inflammation with increased numbers of macrophages and T cells but reduced Forkhead box protein 3(FOXP3) T regulatory cells. Aim: To evaluate the effects of diet-induced weight loss on inflammatory markers and infiltrating cell numbers in colorectal mucosal biopsies of obese women. Methods: 10 healthy pre-menopausal obese women (mean age 43 ± 8 years) were fed a very low calorie diet (VCLD) providing approximately 800 kcals/day in a closely monitored inpatient dietary intervention study to achieve a 10% weight loss. At baseline and after dietinduced weight loss, serum and mucosal cytokines were measured by human proinflammatory 9-plex assay (MSD). Changes in mucosal macrophage, total T cell, regulatory T cell and dendritic subtype cell numbers were determined using CD163, CD3, FOXP3, Langerin, BDCA1 and BDCA2 antibodies. Results: The average prestudy weight of the subjects was 95.9 ± 12.1 kg, BMI was 35 ± 3 kg/m2 and they lost 10.1 ± 1.4 % of their initial weight consuming the VLCD diet in a mean of 6.5 weeks. Diet induced weight loss decreased serum cytokines significantly TNF by 14% (p