Heat-killed M. vaccae NCTC 11659 modulates lipopolysaccharide (LPS)-induced exaggeration of inflammation in THP-1 monocyte-derived macrophages by increasing the ratio of IL10 mRNA expression to IL12B and IL23A mRNA expression, encoding the subunits of the heterodimeric cytokine, IL-23. Gene expression was measured using real-time reverse transcription polymerase chain reaction (RT-PCR) and is represented relative to the highest Cq value for each gene. Data represent means ± SEM. Numbers on the x-axis indicate the concentration of LPS in ng/mL. Data were analyzed using a two-way ANOVA followed by Dunnett’s multiple comparisons test using a single pooled error value from all 20 treatment groups, if appropriate, at a two-tailed alpha level of 0.05. Darker colors represent sequentially higher concentrations of M. vaccae NCTC 11659. * p < 0.05, ** p < 0.01, *** p < 0.001, effect of LPS, within the same M. vaccae NCTC 11659 condition, using the RPMI 1640 groups as the comparison groups. # p < 0.05, ## p < 0.01, ### p < 0.001, effect of M. vaccae NCTC 11659, within the same LPS condition, using the BBS condition as the comparison group. (A) IL10:IL12A mRNA expression ratio upon challenge with different concentrations of M. vaccae NCTC 11659 and LPS. (B) IL10:IL12B mRNA expression ratio upon challenge with different concentrations of M. vaccae NCTC 11659 and LPS. (C) IL10:IL23A mRNA expression ratio upon challenge with different concentrations of M. vaccae NCTC 11659 and LPS. Abbreviations: BBS, borate-buffered saline; LPS, lipopolysaccharide; NCTC, National Collection of Type Cultures. Sample sizes can be found in Table S9 in the Supplemental Information.