Pruritus secondary to primary biliary cholangitis: a review of the pathophysiology and management with phototherapy

BACKGROUND

Primary biliary cholangitis (PBC) is an autoimmune hepatobiliary disorder characterized by destruction of liver bile ducts leading to intrahepatic cholestasis. It causes intractable pruritus for which ultraviolet (UV)B phototherapy is an experimental treatment when alternative therapies fail. The pathophysiology of cholestatic itch and the mechanism of action of narrowband UVB in this condition remains poorly understood.

OBJECTIVES

To summarize the current literature and propose testable hypotheses for the mechanism of action of phototherapy in attenuating itch.

METHODS

A focused PubMed search for articles relating to the pathogenesis of itch in cholestatic disease was performed. A total of 3855 articles were screened and 50 were found suitable for literature review. Evidence from this literature review was combined with author expertise in the area.

RESULTS

Formulated hypotheses focus on the role of bile salts, autotaxin and specific receptors including G-protein-coupled bile acid receptor, Gpbar1 (also known as TGR5) and the nuclear transcription factor farnesoid X receptor.

CONCLUSIONS

Several testable mechanisms through which phototherapy may exert its effects are discussed in this review. The next steps are to carry out an objective assessment of the efficacy of phototherapy in cholestatic pruritus, gain further knowledge on the underlying pathways, and subsequently trial its use against current licensed therapies. Such studies could lead to increased mechanistic understanding, identification of novel therapeutic targets and the potential to refine phototherapy protocols, leading to improved control of itch and quality of life in patients with PBC. What's already known about this topic? Primary biliary cholangitis (PBC) is frequently associated with intractable pruritus for which current treatment options are often unsuccessful. Phototherapy is used as an experimental treatment for PBC-associated pruritus when alternative better-studied treatments fail. What does this study add? This study reviews the current literature on the pathophysiology and management of cholestatic pruritus, an area which remains poorly understood. We propose testable hypotheses of the mechanisms behind the attenuation of cholestatic pruritus with phototherapy.

Is there a correlation between degree of viremia and liver histology in chronic hepatitis C?

OBJECTIVE

To determine the correlation between degree of histological liver damage and serum HCV RNA level in patients of chronic hepatitis C, in order to evaluate the usefulness of HCV RNA estimation as an alternate to liver biopsy.

METHODS

This non-interventional descriptive study, was carried out at the department of Pathology, Army Medical College, Rawalpindi, Pakistan between April and September 2002. Core needle liver biopsies of fifty five patients of chronic hepatitis C were evaluated according to Knodell's histological activity index system. The patients were categorized into four subgroups depending upon the grade and stage of disease according to Desmet's classification, and into three groups according to degree of viremia.

RESULTS

Five patients had mild viremia, 43 moderate and 7 had severe viremia. Seven patients had minimal disease, 9 mild, 22 moderate and 17 had severe chronic hepatitis. Eight patients had no fibrosis, 20 had fibrous portal expansion, 19 bridging fibrosis, and 8 patients had cirrhosis. No significant correlation was found between serum HCV RNA levels and grade or stage of the disease, with correlation coefficients of rs = -.054 and rs = .034 respectively. Moreover, no individual component of the HAI correlated with serum HCV RNA levels.

CONCLUSION

Serum HCV RNA level does not determine the degree of hepatic injury precisely and liver biopsy is necessary to accurately evaluate the extent of liver damage.

Demographic aspects of hepatitis C in northern Pakistan

OBJECTIVE

To find out the prevalence of hepatitis C in various, age, sex and ethnic groups in Pakistan.

SETTING

Specimens obtained from military/civil hospitals and General Practitioners of Rawalpindi Islamabad, region and other areas of Northern Pakistan, in vicinity.

SUBJECTS

Serum of 1710 patients of hepatitis C, diagnosed at Armed Forces Institute of Pathology (AFIP), Rawalpindi between 1st July 1996 and Dec 31, 1997, tested for Anti HCV by 3rd generation Murex Elisa. Required information was collected on a proforma filled for each patient.

RESULTS AND CONCLUSION

The majority of the cases were between 30-60 years of age. There was male preponderance. The infection was more common in Urdu speaking fraction of the patients as compared with others.