Figure 4.

Treatment with TcdB neutralizing antibody bezlotoxumab 24 hours post infection increases survival and prevents systemic disease in CDI, without blocking colonic damage. C57BL/6 J mice (n = 10) were intraperitoneally administered either bezlotoxumab (10 mg/kg) or PBS 24-hours post infection with M7404 C. difficile and were compared to uninfected control mice. a) Weight-loss relative to day zero (D0) and b) Kaplan Meier survival curve of infected + bezlotoxumab (blue), infected + PBS (red), uninfected + bezlotoxumab (Orange) and uninfected + PBS mice (purple). c) Representative scoring of murine sepsis parameters for changes in appearance, activity, eyes and breathing. d) Cumulative colonic histopathology score of four different tissue damage parameters. e) Representative images of Periodic Acid Schiff/Alcian Blue stained Swiss-rolled colonic tissues. Scale bar = 100 µm. Bracket = Crypt hyperplasia, damage or hemorrhage; Yellow arrow = Inflammation; Red arrowhead = Crypt damage or goblet cell loss; Black star = Edema. f) FACS analysis of single positive (SP) CD4⁺ and CD8⁺ T cell populations as well as double positive (DP) CD4⁺CD8⁺ thymocytes in the thymus following CDI and bezlotoxumab intervention. g) Representative images of hematoxylin and eosin-stained thymic sections. C = Cortex; M = Medulla. Scale bar = 1 mm. h) Average counts of macrophage (F4/80 + cells) infiltration into kidney glomeruli, with i) representative images shown. Scale bar = 50 µm; Red arrow = Macrophage. Error bars indicate S.E.M. Statistical analysis by Mann Whitney U test. * = p ≤ .05; ** = p ≤ .01; *** = p ≤ .001; **** = p ≤ .0001.