Figure 2. SM-target normal–abnormal paired sampling for functional analysis of multifocal ileitis in mice.

(a) SM differentiated cobblestone-ileitis disease severity in SAMP mice as a function of age, housing facility and presence of commensal gut flora (GF, germ-free; SPF, specific pathogen free). SM also revealed disease-severity bimodal distribution (inset histogram—facility A, subpopulations of mice ∼50% each with significant severity differences). Facility A and B mice are littermates born in facility A but split as cohort and transferred to facility B at weaning, 4-week-old. (b) Histology showed SM cobblestones have discrete (yes/no) morphological features at villous level that allows 3D-SMAPgut to precisely quantify the extent of abnormal mucosa. Notice transmural histological inflammation and cellularity in serosa. M, mucosa; m, muscular layers; s, serosa. (c) MPO activity in SM paired cobblestones-normal mucosa of co-housed littermates showed increased MPO in cobblestones, and significant overall reactivity in 2/5 of mice. (d) SM-target analysis provides more accurate information compared with blindly collected strip-longitudinal intestinal samples. SM-‘within-mouse case-control' sampling will allow the identification of focal modulating factors for cobblestone formation and other SM-lesion types in IBD. Strips-A and -B represent two groups of six to eight mice; normal-cobbles, represent a third group sampled using SM. (e) TEER ex vivo analysis on SM-dissected cobblestones and SM-normal tissues (Mann–Whitney, n=4–5 per group). (f) Intervention experiments with dexamethasone and DSS showed that SM-target MPO analysis predictably enabled the ability to quantify and differentiate treatment response to therapies across mouse strains and IBD murine models (GLM regression; n=4–8 per group; reproducible in five other comparable experiments). Boxplots in figure display interquartile range boxes, median, min and max values; symbol inside box indicates mean.