Figure 4: CD73−/− mice exhibit ongoing inflammation and slower recovery from IBD compared to WT mice. (a) WT (circles) and CD73−/− (squares) mice were given 3% DSS in drinking water and weighed daily for 35 days. DSS was removed at day 8 and replaced with drinking water. Results are represented as % of initial weight (±SEM, * 𝑃 < 0 . 0 5 , one of two representative experiments). (b) H&E staining of colons from CD73−/− (top) and WT (bottom) mice taken on day 35 (left) compared to naïve (right) mice. (c) Mean (±SEM, * 𝑃 < 0 . 0 5 , ** 𝑃 < 0 . 0 1 ) colonic inflammatory score is displayed ( 𝑛 = 5 mice). The scoring scale is comprised of two components: (i) inflammatory cell infiltrate (focus of inflammatory cells in the lamina propria = 1, confluence of inflammatory cells = 2, and transmural extension of the infiltrates = 3); (ii) tissue damage (discrete lymphoepithelial lesions = 1, mucosal erosion = 2, and extensive mucosal damage and extension through deeper structures of the bowel wall = 3). (d) FACS analysis of CD73 expression on colonic epithelial cells from naïve WT (top left panel, 28%) and CD73−/− (bottom left panel, 0%) mice. Colonic epithelial cells identified with CD326/EpCam. Colonic IEL’s identified with CD45 (middle panels, WT 87% CD73+). Mesenteric lymph nodes shown as a positive control (right panels, WT 39% CD73+). (e) IL-1β and TNFα production in colon preparation isolated from WT and CD73−/− mice on day three of DSS treatment and (f) day eight of DSS treatment. (g) Colons isolated from WT and CD73−/− mice on day 22 after removal of DSS were cultured (in medium alone) for 24 hours and supernatant analyzed by Bio-Plex for IL-1β. Results (mean ±SEM, * 𝑃 < 0 . 0 5 , representative of one experiment, 𝑛 = 3 mice per group) are presented as pg/mL IL-1β produced.