Modulation of the gut microbiota and the microbial-produced gut metabolites by diclofenac exposure and selenium supplementation.

Diclofenac (DCF) exposure is of great concern due to the ecotoxicological risk linked with a decline of vulture populations in Southeast Asia, but also because it can affect the reproduction and neurotoxicity in mammals. Otherwise, selenium (Se) is an antioxidant essential element with key roles in health and with antagonistic action against pollutants, but in some cases with a synergistic effect. To investigate the potential intertwined mechanisms between DCF, Se, and gut microbiota, gut metabolomic and gut microbiota profiles were determined in mice after DCF exposure and Se supplementation. Speciation of selenoproteins in plasma was carried out by isotopic dilution analysis to quantify the levels of selenoproteins. Significant differences in the levels of 79% of the gut metabolites were determined after DCF exposure. The most significant altered pathway in DCF and DCF-Se groups is the primary bile biosynthesis, being the only pathway altered in mice exposed to DCF, while in DCF-Se, the metabolism of galactose and linoleic acid is also altered. Moreover, specific associations between specific gut microbiota and metabolites were determined in the studied mice groups suggesting intertwined mechanisms. Selenium supplementation modulated the gut metabolic and microbiota profiles affected by DCF.