Pruritus and fatigue in primary biliary cirrhosis

Cholestasis, a condition characterized by an abnormal decrease in bile flow, is accompanied by various symptoms such as pruritus. Although cholestatic pruritus is a prominent condition, its precise mechanisms have largely been elusive. Recently, advancements have been made for understanding the etiology and pathogenesis of cholestatic pruritus. The current review therefore focuses on summarizing the overall progress made in the elucidation of its molecular mechanisms. We have reviewed the available animal models on cholestasis to compare the differences between them, characterized potential pruritogens involved in cholestatic pruritus, and have summarized the receptor and ion channels implicated in the condition. Finally, we have discussed the available treatment options for alleviation of cholestatic pruritus. As our understanding of the mechanisms of cholestatic pruritus deepens, novel strategies to cure this condition are awaited.

Since the discovery of the impact of serotonin in liver regeneration, this molecule has gained considerable attention in liver physio-pathology. Platelet-derived serotonin initiates liver regeneration after partial hepatectomy in various rodent models. Serotonin agonism stabilizes the hepatic microcirculation and prevents small-for-size liver graft failure. Similarly, serotonin receptor agonists improve the sinusoidal perfusion of aged liver and restore the deficient liver regeneration in old mice through a pathway dependent on vascular endothelial growth factor. Beside hepatocyte proliferation, cholangiocytes have been shown to be able to deploy serotonin as an autocrine/paracrine signal to regulate regeneration of the biliary tree.

Increasing evidence indicates that serotonin is involved in many pathological conditions of the liver. For example, serotonin promotes tissue repair after ischemia/reperfusion injury. Reactive oxygen species generated by serotonin degradation contribute to steatohepatitis in rodent models. Serotonin aggravates viral hepatitis, again through vasoactive effects on the microcirculation, and plays a crucial role in the progression of hepatic fibrosis. Finally, serotonin may facilitate tumor growth of primary liver carcinoma like cholangiocarcinoma and hepatocellular carcinoma. These findings make serotonin both friend and foe for the liver. Whichever, these new data emphasize the potential of serotonin as a pharmacological target in liver disease.

Background and aim: Primary biliary cirrhosis (PBC) is a chronic cholestatic disease of autoimmune origin and has a genetic component. Although it has been reported that the prevalence of the HLA-DRB1*08 allele is high in various populations, the prevalence of HLA alleles in Mexican PBC patients has not been described. The aim of this study was to quantify the prevalence of HLA-B/-DR alleles in Mexican PBC patients.

Materials and methods: A case-control transversal study was performed during January and July 2008 with adult patients diagnosed with PBC. Cases were defined as subjects with PBC and controls were obtained from healthy subjects evaluated for bone marrow transplantation. Laboratory was performed at the moment of diagnosis. HLA-B/-DR allele frequency was obtained by gene counting and allele presence was determined by PCR-SSP procedure. Descriptive statistics between groups was evaluated by Chi-square with Yates correction.

Results: Nine patients (seven females and two males, mean ± SD age = 57.5 ± 10.5 years) were studied. The most prevalent alleles were HLA-DRB1*01 (n = 4), DRB1*04 (n = 4), B*39 (n = 34), B*14 (n = 3), and B*51 (n = 2). Linkage disequilibrium was detected for alleles HLA-B*39/DRB1*04 (n = 3), HLA-B*14/HLA-DRB1*01 (n = 2), and B*51-DRB1*04 (n = 1).

In conclusion:Mexican PBC patients express genes of native and Mediterranean origin.

Autoimmune liver disease (ALD) includes a spectrum of diseases which comprises both cholestatic and hepatitic forms: autoimmune hepatitis (AIH), primary biliary cirrhosis (PBC), primary sclerosing cholangitis (PSC) and the so called “overlap” syndromes where hepatitic and cholestatic damage coexists. All these diseases are characterized by an extremely high heterogeneity of presentation, varying from asymptomatic, acute (as in a subset of AIH) or chronic (with aspecific symptoms such as fatigue and myalgia in AIH or fatigue and pruritus in PBC and PSC).

The detection and characterization of non organ specific autoantibodies plays a major role in the diagnostic approach of autoimmune liver disease; anti nuclear reactivities (ANA) and anti smooth muscle antibodies (SMA) mark type 1 AIH, liver kidney microsomal antibody type 1 (LKM1) and liver cytosol type 1 (LC1) are the serological markers of type 2 AIH; antimitochondrial antibodies (AMA) are associated with PBC, while no specific marker is found in PSC, since anticytoplasmic neutrophil antibodies with perinuclear pattern (atypical p-ANCA or p-ANNA) are also detected in a substantial proportion of type 1 AIH cases.

Treatment options rely on immunosoppressive therapy (steroids and azathioprine) in AIH and on ursodeoxycholic acid in cholestatic conditions; in all these diseases liver transplantation remains the only therapeutical approach for the end stage of liver disease.