Hepatobiliary bile secretion pathway

The hepatobiliary bile secretion pathway is a fundamental physiological process involving the synthesis, transport, and excretion of bile acids, bilirubin, and cholesterol from the liver into the biliary system [1]. This pathway is mediated by a sophisticated network of membrane transporters located on the basolateral and apical membranes of hepatocytes, such as the Bile Salt Export Pump (BSEP) and the Sodium-taurocholate Cotransporting Polypeptide (NTCP) [2, 3]. Beyond its role in the digestion and absorption of dietary fats and fat-soluble vitamins, the pathway serves as a major route for the elimination of metabolic waste and xenobiotics [4]. Impairment of this pathway, often referred to as cholestasis, results in the intrahepatic accumulation of bile acids, leading to hepatocellular injury, inflammation, and potentially end-stage liver disease [3]. Therapeutic interventions often target specific components of this pathway, such as the Farnesoid X Receptor (FXR) to modulate transporter expression or the inhibition of intestinal bile acid reabsorption to reduce the total bile acid pool [5]. Understanding the molecular mechanisms of this pathway is crucial for drug development and for predicting drug-induced liver injury (DILI) [2].

Other names

Bile secretion pathwayHepatobiliary transport systemBiliary secretion

Drugs targeting this pathway function by activating nuclear receptors (e.g., FXR, PXR, PPAR-alpha) to regulate the expression of bile acid transporters, providing hydrophilic bile acids to dilute toxic ones, or inhibiting the enterohepatic circulation of bile acids to reduce hepatic load [1, 3, 5].