B D 口 Vehicle o uncommon 80 口 Clostridiaceae Butyrate producers WT Pparg WT Pparg ui WT Pparg DLachnospiraceae E98o85 ■WT口Pg6s1021口ho■c7日m gO LIN 88 t 9 c17 Figure 2. Microbiota-induced epithelial PPAR-y-signaling limits nitrate availability in the colon (A)Nos2 expression in the colonic epithelium of mice(N= 6) was determined by real-time PCR in Ppargfili villifrel- mice(Pparg) which lack PPAR-y in epithelial cells, and in littermate control Pparg villin/mice(WT).( B)Relative abundance of families belonging to the class Clostridia in colon contents of mice(N=6) was determined by 16s profiling.( C) The butyrate concentration was determined in cecal contents of mice(N= 6) using gas chromatography. (D) Mice(N=6)were inoculated with a 1: I mixture of E. coli wild type(wt)and napA narG narZ mutant and received aminoguanidine(AG) supplementation or vehicle control. The competitive index( CI; the ratio of wt and napA narG narZ mutant recovered from colon contents) was determined 3 days after inoculation. (E)The concentration of nitrate in the colonic mucus layer was determined in groups of animals(N=9) by a modified Griess assay. (F and g) Streptomycin-treated mice(N=6) were inoculated with E. coli indicator strains and received supplementation with tributyrin or a community of 17 human Clostridia isolates( C17). The butyrate concentration in cecal contents (F)and the CI in colon contents(G)were determined 3 days after inoculation. (A, C and F) Bars represent geometric means t standard error. (D, E and g) Each dot represents data from an individual animal and black bars represent geometric means. " P<0.05.,P <0.01; ns, not statistically significantly different. Science Author manuscript; available in PMC 2017 October 1Figure 2. Microbiota-induced epithelial PPAR-γ-signaling limits nitrate availability in the colon (A) Nos2 expression in the colonic epithelium of mice (N = 6) was determined by real-time PCR in Pparg fl/flVillin cre/− mice (Pparg), which lack PPAR-γ in epithelial cells, and in littermate control Pparg fl/flVillin −/− mice (WT). (B) Relative abundance of families belonging to the class Clostridia in colon contents of mice (N = 6) was determined by 16S profiling. (C) The butyrate concentration was determined in cecal contents of mice (N = 6) using gas chromatography. (D) Mice (N = 6) were inoculated with a 1:1 mixture of E. coli wild type (wt) and napA narG narZ mutant and received aminoguanidine (AG) supplementation or vehicle control. The competitive index (CI; the ratio of wt and napA narG narZ mutant recovered from colon contents) was determined 3 days after inoculation. (E) The concentration of nitrate in the colonic mucus layer was determined in groups of animals (N = 9) by a modified Griess assay. (F and G) Streptomycin-treated mice (N = 6) were inoculated with E. coli indicator strains and received supplementation with tributyrin or a community of 17 human Clostridia isolates (C17). The butyrate concentration in cecal contents (F) and the CI in colon contents (G) were determined 3 days after inoculation. (A, C and F) Bars represent geometric means ± standard error. (D, E and G) Each dot represents data from an individual animal and black bars represent geometric means. *, P < 0.05; **, P < 0.01; ns, not statistically significantly different. Byndloss et al. Page 18 Science. Author manuscript; available in PMC 2017 October 16. Author Manuscript Author Manuscript Author Manuscript Author Manuscript