Serum Autotaxin Activity Correlates With Pruritus in Pediatric Cholestatic Disorders

Objective: Pruritus is a common symptom of cholestatic liver disorders. The present study aimed at evaluating autotaxin (ATX), a lysophospholipase recently identified as potential cause for cholestatic pruritus, in pediatric cholestatic diseases presenting with or without itching. Methods: A cohort of 45 children consisting of 14 patients experiencing itching (Alagille syndrome [n = 10], complete extrahepatic biliary atresia [n = 2], neonatal sclerosing cholangitis (n = 1), progressive familial intrahepatic cholestasis type 2 [n = 1]), 9 patients with bile acid synthesis defects (3 beta-hydroxy-C27-steroid-oxidoreductase [n = 7] and Delta(4)-3-oxosteroid-5 beta-reductase deficiency [n = 2]), and 22 healthy children were studied. Serum ATX activity and total serum bile salt were determined enzymatically, ATX protein content was semiquantified by Western blotting. Using real-time polymerase chain reaction, ATX mRNA expression was studied in HepG2 cells treated with farnesoid-X-receptor agonists or vehicle. Results: Serum ATX activity was increased in pruritic children with Alagille and other cholestatic syndromes (mean +/- standard deviation: 16.1 +/- 4.3 nmol center dot mL(-1) center dot min(-1)) compared with children with nonpruritic cholestatic diseases with bile acid synthesis defects (10.4 +/- 4.7 nmol center dot mL(-1) center dot min(-1); P < 0.01) and healthy controls (7.6 +/- 2.3 nmol center dot mL(-1) center dot min(-1); P < 0.001). ATX protein levels closely correlated with serum ATX activity. Serum ATX activity and total serum bile salt showed a linear correlation with itch intensity (r = 0.66, P r = 0.80, P < 0.001, respectively). No correlation was observed between ATX activity and bilirubin. ATX mRNA expression in HepG2 cells was not induced by farnesoid-X-receptor ligands. Conclusions: Serum ATX activity correlated with itch intensity in children with cholestatic diseases. Bile salts did not increase ATX expression in vitro. ATX inhibitors may be useful antipruritic agents in pediatric cholestatic disorders.