Survival (A), GVHD clinical score (B), and histopathological score of skin (C) in imipenem-treated mice following HSCT, with and without GOS supplementation. GOS supplementation significantly improved survival (n = 12 mice per treatment group, n = 5 in “No Tcell control,” P = .0087, log-rank test; hazard ratio = .224, Cox regression, A). GVHD clinical score, an observational indicator of GVHD severity, was assessed weekly following transplantation for each mouse (n = 15 per group, B). Presence of GVHD and its severity was calculated out of six categories: body weight, skin, fur, posture, and activity as well as diarrhea (supplemental Table 1). This combined score was lower on Day 14 in GOS-supplemented mice (P < .0001, Tukey’s honestly significant difference post-hoc test following significant ANOVA, P = .0005). Tissue samples of skin were taken from the back of the neck and scored with a semiquantitative system for documenting GVHD damage with criteria as outlined in supplemental Table 2.25 Total skin score (a histological indicator of GVHD-mediated tissue damage in skin, graded by a blinded and independent pathologist) was assessed at Day 14 post-transplant in all surviving mice (three of 15 in GOS-free group, 10 of 15 in GOS group, C, P values calculated with Wilcoxon tests). Mean and standard error are depicted by larger points and error bars (B-C).
