Abstract Background We have shown that maternal high fat diet exposure (mHFD) results in a microbiota-dependent expansion of IL-17 producing type 3 innate lymphoid cells (ILC3) in offspring. We hypothesized that the unique mHFD microbiome in offspring would result in an altered metabolite profile that could potentiate Ahr signaling and ILC3 function. Methods Murine offspring exposed to 60% mHFD were examined at 2-weeks old. Stool was examined by high-throughput, non-targeted mass spectroscopy-based metabolic analysis. Microbial colonization was examined by next generation sequencing. 2-week-old small intestine (SI) from regular diet (RD) offspring was exposed to selected indole metabolites for 24 hours and supernatant examined by ELISA. For in vivo experiments, bacteria was gavaged to RD offspring beginning at 5 days old. Flow cytometry of SI lamina propria cells was used to examine ILC3. Results mHFD offspring had a differential pattern of colonization and metabolite composition. mHFD offspring had a consistent expansion of Lactobacillus murinus. In vivo exposure to L. murinus resulted in a 30% increase in IL-17 producing ILC3 not seen with exposure to L. rhamnosus. Metabolomics of stool from mHFD offspring showed a decrease in indole-3-acetate and 3-methyldiozyindole (p<0.00001). SI stimulated with indole metabolites showed a 50% decrease in production of IL-17 (p<0.05) and IL-22 (p<0.05). Conclusion L. murinus is specifically expanded in mHFD offspring and can increase IL-17 producing ILC3. L. murinus may expand ILC3 by differential metabolism of indole metabolites. Metabolism of indole metabolites by L. murinus and their role on Ahr signaling need to be further examined as a mechanism of modulating ILC3 response in offspring.