Cholesterol metabolism in cholestatic liver disease and liver transplantation: From molecular mechanisms to clinical implications

Figure 1 From the gut to the circulation: An overview of the pathways involved in cholesterol absorption and synthesis. IDL: Intermediate density lipoprotein; HDL: High density lipoprotein; LDL: Low density lipoprotein; VLDL: Very low density lipoprotein; NPC1L1: Niemann-Pick C1 like 1; ABCG5: Adenosine triphosphate-binding cassette transporter G5 heterodimer; HMGCoA: 3-hydroxy-3-methyl-glutaryl CoA; FXR: Farnesoid X receptor.

Figure 2 One key event in cholesterol homeostasis is the gated movement of sterol regulatory element-binding protein isoform 2 from the endoplasmic reticulum to the Golgi complex, involving the cleavage-activating protein, and INSIG-2. SREBP-2: Sterol regulatory element-binding protein isoform 2; ER: Endoplasmic reticulum; SCAP: Cleavage-activating protein.

Figure 3 Cholesterol elimination- mechanisms and key transporters. Expansion of the cholesterol pool activates liver X receptor, thereby generating transcriptional responses resulting in cholesterol excretion and catabolism. NPC1L1: Niemann-Pick C1 like 1; ABCA1: ATP-binding cassette transporter sub-family member A 1, also known as the cholesterol efflux regulatory protein; ACAT2: Acetyl-CoA acyltransferase 2; ABCG5: Adenosine triphosphate-binding cassette transporter G5 heterodimer; HDL: High density lipoprotein.

Figure 4 Algorithm for assessing hyperlipidemia in the setting of chronic liver disease. LDL: Low density lipoprotein; ALP: Alkaline phosphatase.