Mutation of keratin 8 in patients with liver disease

Abstract

Epithelial tissues of the gastrointestinal tract and the liver express predominantly cytokeratin 8 and cytokeratin 18. In vitro experiments and animal studies have demonstrated a protective influence of keratin 8 and keratin 18 against toxic damage of hepatocytes. A specific mutation of keratin 8 (G61C) was found to be a genetic risk factor for the development of cryptogenic liver cirrhosis. The purpose of the present paper was therefore to determine the prevalence of cytokeratin 8 (G61C) and cytokeratin 18 mutations (Y53H) in patients with liver disease. Overall 152 patients (male, n = 93, 61%; female, n = 59, 39%) were included in the present study. The 152 patients consisted of 107 patients with liver disease (70.4%; male, n = 71, 66.4%; female, n = 36, 33.6%) and 45 control patients (29.6%; male, n = 22, 48,9%; female, n = 23, 51,1%) without liver disease. Of the patients with liver disease 46 had alcoholic liver disease; 25, chronic hepatitis C; 15, cryptogenic liver disease; and 21, other liver diseases of various etiologies. Cytokeratin 8 and 18 genotypes were specified by polymerase chain reaction (PCR) amplification and direct sequence analysis was used to detect the previously described mutations in cytokeratin 8 (G61C) and in cytokeratin 18 (Y53H). Four out of 152 patients (male n = 2, female n = 2) with a mutation (G61C) in cytokeratin 8 were found. The etiology was alcoholic liver disease (n = 1), cryptogenic liver disease (n = 1) and idiopathic liver disease with minimal changes in liver biopsy (n = 1). Also, one out 45 disease control patients with an adenoma of the colon but without liver disease was found to carry the mutation G61C of cytokeratin 8. Therefore, the mutation G61C in cytokeratin 8 was found in 2.8% of patients with liver disease and in 2.2% of control patients without liver disease. Two of 15 patients (13.3%) with cryptogenic liver disease had the mutation G61C in cytokeratin 8 (P = 0.069 vs patients with non-cryptogenic liver disease). In the 152 patients studied, no mutation in cytokeratin 18 was found. The mutation G61C in the cytokeratin 8 gene was found in one patient with alcoholic liver disease and in two patients with liver disease of unknown etiology. Also, one patient without liver disease had the cytokeratin 8 G61C mutation. In summary, the cytokeratin 8 mutation G61C, which has been found to be associated with cryptogenic liver cirrhosis, was also found in the present patient population. However, the clinical relevance is yet to be determined in further investigations.