Fig. 3

The protective effect of BHB against colitis is depending on colonic macrophages. a, b Littermate WT mice (n = 5 per group) were intraperitoneally injected with clodronate liposomes (4 ml/kg) or PBS as a control once a day for 5 days. Their colonic tissues were collected for IHC analyses to determine the efficiency of macrophage depletion. a Representative IHC images of F4/80 immunostaining in the colon tissues (scale bars: 150 μm). b The number of colonic F4/80⁺ immune cells per 300 μm². F4/80⁺ cells were counted under a microscope. c–h Littermate WT mice (n = 7 to 8 per group) received BHB or saline enema were given DSS in drinking water to induce experimental colitis as described in Fig. 1a. For macrophage depletion, clodronate liposomes (4 ml/kg) were intraperitoneally injected once a day for 5 days prior to DSS treatment and on days 2, 4, and 6 after the start of DSS treatment. c, d Body weight changes and disease activity index were monitored daily after DSS treatment. e Representative images of the colons. f Mice were killed on day 18, and colon lengths were measured. g, h Colon sections were examined histologically. g Histology scores for colonic inflammation were measured. h Representative images of the H&E-stained colon sections of different treatment groups (scale bars: 150 μm). b–d, f, g Data represent means ± SEM; NS, not significant; **P< 0.01 by unpaired Student’s t test. Data shown are representative of three independent experiments