Cholestatic pruritus: a knowledge update

Structure-guided discovery of bile acid derivatives for treating liver diseases without causing itch

Chronic itch is a debilitating symptom profoundly impacting the quality of life in patients with liver diseases like cholestasis. Activation of the human G-protein coupled receptor, MRGPRX4 (hX4), by bile acids (BAs) is implicated in promoting cholestasis itch. However, the detailed underlying mechanisms remain elusive. Here, we identified 3-sulfated BAs that are elevated in cholestatic patients with itch symptoms. We solved the cryo-EM structure of hX4-Gq in a complex with 3-phosphated deoxycholic acid (DCA-3P), a mimic of the endogenous 3-sulfated deoxycholic acid (DCA-3S). This structure revealed an unprecedented ligand-binding pocket in MRGPR family proteins, highlighting the crucial role of the 3-hydroxyl (3-OH) group on BAs in activating hX4. Guided by this structural information, we designed and developed compound 7 (C7), a BA derivative lacking the 3-OH. Notably, C7 effectively alleviates hepatic injury and fibrosis in liver disease models while significantly mitigating the itch side effects.

Odevixibat: A Novel Bile Salt Inhibitor Treatment for Pruritus in Progressive Familial Intrahepatic Cholestasis

Chronic pruritus is defined as an itch lasting greater than six weeks. It can manifest from a wide variety of etiologies, as many different substances can act as pruritogens, such as steroids, histamine, progesterone, endogenous opioids, and serotonin. In the setting of cholestatic liver disease, increased bile acids play a major role in chronic pruritus. The itching in cholestatic liver disease is worsened in intensity at night and localized frequently to the palms, soles, knees, and other pressure sites. It can be hard to manage, affecting the quality of sleep and causing irritability, poor attention, and, in some cases, depression. One such disease that results from chronic pruritus is progressive familial intrahepatic cholestasis (PFIC), a group of uncommon hereditary disorders that affects the formation of bile and its outflow from the liver. Previously, the drug ursodeoxycholic acid was used to help manage pruritus or surgical procedures, e.g., partial external biliary diversion or partial internal biliary diversion, to help control complications of the disease. This literature review will discuss three clinical studies covering the effectiveness of odevixibat in treating pruritus in patients with PFIC. Odevixibat (Bylvay) is an oral drug that has been FDA-approved to treat pruritus in patients three months of age and older with PFIC. Odevixibat prevents the reabsorption of bile salts in the intestines, resulting in decreased levels of bile salts via their excretion in stool. Several studies have determined that the drug is well tolerated and provides a nonsurgical, pharmacological treatment alternative for those with PFIC.

Systemic Complications of Primary Biliary Cholangitis

Chronic cholestasis is the hallmark clinical feature of primary biliary cholangitis. In addition to progressive liver damage, chronic cholestasis can lead to serious complications, many of which occur outside the liver. Bile acids are ligands for nuclear hormone receptors, and alterations in their concentration disrupt normal functioning of numerous different cell types. This article discusses the clinical presentation, pathophysiology, and management of pruritus (itching), fatigue, osteoporosis, hyperlipidemia, fat-soluble vitamin deficiencies, malignancies, cardiac dysfunction, bacterial cholangitis, cholemic (bile cast) nephropathy, and Sicca syndrome.

Cholestatic Pruritus Mimicking a Cutaneous Drug Eruption

Pruritus, colloquially known as itch, is a common clinical symptom seen in a variety of dermatological conditions and systemic disorders. Pruritus can broadly be classified into four categories: neuropathic, neurogenic/systemic, psychogenic, and pruritoceptive. Initial categorization depends on anatomical and pathophysiological aspects of presentation and is reflective of underlying etiology. We report a case of an 83-year-old man presenting with generalized pruritus secondary to cholestasis from bile duct malignancy. This case is notable for atypical presenting features, including a trunk eruption comprised of excoriated papules with onset following meloxicam initiation, mimicking a cutaneous adverse drug reaction. Providers should consider systemic etiologies of pruritus in patients presenting with cutaneous eruptions with atypical features. Accurate categorization of pruritus can facilitate treatment and/or additional investigation of systemic disease.

[Management of pruritus in the elderly]

BACKGROUND

Chronic pruritus (CP), a frequent (20.3%) symptom in the elderly, increases with age. It has a significant impact on the quality of life, ranking among the 50 most burdensome diseases worldwide (Global Burden of Disease Study).

OBJECTIVES

The aim is to provide an overview of the symptom CP in the elderly and to improve differentiation of underlying conditions and management of this entity.

MATERIALS AND METHODS

A literature search in PubMed was performed, using the terms 'pruritus', 'elderly' and 'gerontodermatology'.

RESULTS

The main causes of CP in the elderly are the physiologic aging process (xerosis cutis, immunosenescence, neuropathy), the increase in potentially pruritic diseases with increasing age (diabetes mellitus, chronic renal failure), and polypharmacy. Therapeutic options relate to causes, severity of pruritus, and individual patient factors (multimorbidity, impaired organ function). The recently updated S2k guideline 'Diagnosis and therapy of chronic pruritus' is helpful.

CONCLUSION

CP in the elderly is challenging for both patients and physicians. Not only the difficulty of identifying the underlying cause, but the complexity of treatment and its tolerability and practicability determines these patients' further burden.

Systematic review: efficacy of therapies for cholestatic pruritus

Background

Pruritus is a symptom of several cholestatic liver diseases (CLDs) that can impair health-related quality of life (HRQoL). Despite evidence-based guideline therapy, managing cholestatic pruritus (CP) remains challenging, thus making the need for newer, more effective therapeutic agents more evident.

Objective

Our study evaluated the efficacy of existing CP therapies.

Design

Systematic review.

Data sources

From inception until March 2023, we conducted a comprehensive search of MEDLINE, Cochrane, EMBASE, Scopus, ClinicalTrial.gov, and other sources, including pharmaceutical webpages and conference proceedings published in English that reported on CP interventions.

Methods

Two reviewers independently conducted screening and full-text review of articles with extraction conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. The methodological quality of studies included in our qualitative synthesis was assessed by using the Cochrane ROBINS-I and ROBINS-II tools for interventional studies and the National Heart, Lung, and Blood Institute Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. The primary outcome assessed in our systematic review was the severity of CP after therapy.

Results

Of 3293 screened articles, 92 studies were eligible for inclusion in the qualitative synthesis. Some patients' HRQoL improved with evidence-based standard therapy. Others, particularly those with severe and refractory CP, often required conversion to or addition of experimental noninvasive (e.g., ondansetron) or extracorporeal liver support to alleviate CP. In addition, studies investigating a newer class drug, the ileal bile acid transporter inhibitor (IBATi), demonstrate its effectiveness in reducing serum bile acid and alleviating CP with sustained improvement noted in patients with the inherited childhood cholestatic disorders - progressive familial intrahepatic cholestasis and Alagille syndrome.

Conclusion

Our findings consolidate data on the efficacy of guideline-based approaches and newer therapies for CP. While the initial findings are promising, additional clinical trials will be needed to determine the full extent of IBATi's efficacy and potential use in treating other common CLDs. These results provide a foundation for future research and highlight the need for continued investigation into the management and treatment of CLDs.