fig4

Figure 4. Roles of bile acids (BAs). Primary BAs, synthesized from cholesterol, are converted by gut microbiota into secondary bile acids in the intestinal lumen. Most of primary and secondary BAs traverse the intestinal epithelium and participate in enterohepatic circulation. BAs exert anti-vascular aging effects by modulating lipid and energy metabolism and improving endothelial function. (Created in BioRender. Raitasi, E. (2026) https://BioRender.com/inv9no8). CYP7A1: Cholesterol 7α-hydroxylase; CYP27A1: sterol 27α-hydroxylase; CA: cholic acid; CDCA: chenodeoxycholic acid; ASBT: apical sodium-dependent bile acid transporter；FXR: farnesoid X receptor; TGR5: takeda G-protein-coupled receptor 5; FGF19: fibroblast growth factor 19; ABCG5/8: ATP-binding cassette subfamily G members 5 and 8; OST: organic solute transporter; NTCP: sodium taurocholate cotransporting polypeptide; FGFR4: fibroblast growth factor receptor 4; β Klotho: beta-Klotho; SHP: small heterodimer partner; LXR: liver X receptor; SREBP-1c: sterol regulatory element binding protein-1c; ApoCIII: apolipoprotein CIII; PPAR: peroxisome proliferator-activated receptor; FMO: flavin-containing monooxygenase; TMAO: trimethylamine N-oxide; PIEZO1: PIEZO-type mechanosensitive ion channel component 1; NOS: NO synthase; WNT2: wingless-type MMTV integration site family member 5; FZD5: frizzled class receptor 5; SCARB1: scavenger receptor class B member 1; DIO2: iodothyronine deiodinase 2; ET-1: endothelin-1; PHB-1: prohibitin-1; ATF4: activating transcription factor 4; ED: endothelial dysfunction.