Periodontitis salivary microbiota stimulates the tryptophan-kynurenine-AhR axis in the liver
(A) Heatmap of the top 50 differential metabolites in VIP-value between P_HFD and HFD groups.
(B) KEGG pathway analysis of the top 20 enriched metabolic pathways in the P_HFD and HFD groups.
(C–E) Relative concentrations of L-kynurenine, L-tryptophan, and the Kyn/Trp ratio in liver tissues.
(F) Spearman’s correlation analysis between Kyn/Trp and liver TG, TC, serum ALT, AST.
(G–K) Relative mRNA levels of TLR4, IL-1β, TNF-α, IDO1, and AhR.
(L) IHC staining of AhR in liver tissues. ∗p < 0.05, ∗∗p < 0.01, ∗∗∗p < 0.001. AhR, aryl hydrocarbon receptor; ALT, alanine aminotransferase; AST, aspartate aminotransferase; HFD, high-fat diet; IDO1, indoleamine 2,3-dioxygenase 1; IHC, immunohistochemical; IL, interleukin; Kyn/Trp, ratio of L-kynurenine to L-tryptophan; P_HFD, high-fat diet + periodontitis salivary microbiota; TC, total cholesterol; TG, total triglyceride; TLR, toll-like receptor; TNF, tumor necrosis factor; VIP, variable importance for the projection.