Reciprocally, Kyn levels were significantly elevated in the brains and guts of both CRS and CRS + DEP-tr mice, while microbiota from HC adolescents strikingly suppressed KP activation, as the levels of Kyn and its downstream neurotoxic metabolites, namely 3-HK and Quin, dramatically decreased (Fig. 5A, B). This evidence concerns the gene NPPA and congenital rubella syndrome.