Pruritus in Chronic Cholestatic Liver Diseases, Especially in Primary Biliary Cholangitis: A Narrative Review

Abstract

Patients with chronic cholestatic liver diseases often experience itch and struggle with this symptom. We discuss the mechanism of itch in patients with chronic cholestatic liver diseases, such as primary biliary cholangitis (PBC) and others, and their therapies, including ileal bile acid transporter (IBAT) inhibitors. In patients with PBC, there are high serum/plasma concentrations of multiple factors, including bile salts, bilirubin, endogenous opioids, lysophosphatidic acid (LPA), autotaxin, and histamine. Bile salts, bilirubin, LPA, and autotaxin affect itch mediators in the skin and sensory nerves, while the endogenous opioid balance affects mediators in the spinal cord. Itch is sensitized by both the peripheral and central nervous systems. Both mechanisms are involved in itch in patients with chronic cholestatic liver disease. Although IBAT inhibitors have been approved for use in pediatric cholestatic conditions, such as progressive familial intrahepatic cholestasis and Alagille syndrome, IBAT inhibition seems to be a promising treatment for chronic refractory itch in patients with PBC. A traditional non-systematic review results in this narrative review. Multidisciplinary cooperation, involving hepatologists, dermatologists, and pharmacists, could provide better treatment for PBC patients suffering from refractory itch. In conclusion, we summarized the existing knowledge on itch caused by chronic cholestatic liver diseases, especially in PBC with a focus on the mechanisms and therapies. This narrative review provides the mechanisms and therapeutic options for itch in patients with chronic cholestatic liver diseases.

Keywords: autotaxin; ileal bile acid transporter inhibitors; liver diseases; primary biliary cholangitis; pruritus.

Figure 1

Representative mechanism of itch in chronic cholestatic liver diseases. Both the peripheral and central nervous systems are involved in chronic itch from liver diseases. LPA, lysophosphatidic acid; TRPA1, transient receptor potential ankyrin 1; TRPV1, transient receptor potential vanilloid 1; MRGPRX4, Mas-related G protein-coupled receptor X4; TGR5, Takeda G protein-coupled receptor 5 (G protein-coupled bile acid receptor 19). Yellow star, diseases; Blue lightning, itch.

Figure 2

Mechanism of ileal bile acid transporter (IBAT) inhibitors. IBAT is involved in the absorption of bile acid (BA) from the terminal ileum to the portal blood flow. IBAT inhibitor blocks the inflow of BA into the portal vein. Red triangle, IBAT inhibitors; Brown circles, IBAT.