Fig. 1

Effect of early-life antibiotic exposure on the severity of DSS-induced colitis. a Schematic of early DSS experiment, using a single 5-day antibiotic course (PAT). C57BL/6 mouse study groups were control/H2O (n = 15), PAT/H2O (n = 16), control/DSS (n = 16), and PAT/DSS (n = 16). Nursing dams received either tylosin or non-acidified drinking water when their pups were between 5 and 10 days old (P5-P10), and pups were exposed to tylosin or not through their mother’s milk. Experimental colitis was induced at P25 by adding 2% DSS to the pup’s drinking water or not for 7 days, and mice were sacrificed at P34. b Normalized percent weight decrease between the groups, measured from P25, the first day of the DSS challenge. c Presence of blood during and after the DSS challenge was scored as 0 (no blood), 1 (hemoccult positive), 2 (hemoccult positive and visual pellet bleeding), or 4 (gross bleeding, blood around the anus). d Stool consistency during and after the DSS challenge was scored as [0 (normal), 2 (loose stool), or 4 (diarrhea)] e Fecal lipocalin-2 levels (ng/mL) at P34; control/H2O (n = 6), PAT/H2O (n = 12), control/DSS (n = 16), and PAT/DSS (n = 16). f Histology scores (total of inflammation, epithelium damage, atrophy, and dysplasia scores); control/H2O (n = 4), PAT/H2O (n = 4), control/DSS (n = 4), and PAT/DSS (n = 3) g Colonic lamina propria Th17 and Treg cells shown as absolute cell numbers and as percent of total CD4 cells; control/H2O (n = 3), PAT/H2O (n = 3), control/DSS (n = 3), and PAT/DSS (n = 3). Two-way ANOVA, Kruskal-Wallis non-parametric test and Dunn’s multiple comparison testing were used for multiple comparisons. *p < 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001