An Interleukin-6 (IL-6) Receptor Polymorphism Affecting Serum Levels of IL-6 Does Not Increase the Risk of Cholangiocarcinoma in Primary Sclerosing Cholangitis

摘要

We read with great interest the article by Cheon et al. (1) on the diagnostic utility of serum interleukin-6 (IL-6) levels in primary bile duct cancer. In patients with primary sclerosing cholangitis (PSC), cholangiocarcinoma (CCA) is a common and severe complication (2). Genetic polymorphisms may serve as markers of a greater CCA risk (3) and could, in the future, aid in the identification of patients in need of frequent surveillance for CCA development.Recently, a nonsynonymous single nucleotide polymorphism (SNP) in the IL-6 receptor gene (rs8192284) was found to affect the circulating levels of IL-6 in large panels of healthy European Americans as well as African Americans, using so-called admixture mapping (4). In the context of the findings of Cheon et al. and the observation that IL-6 enhances the growth of malignant cholangiocytes in experimental models (5), we investigated the possibility that PSC patients with CCA may possess a genetic background associated with high IL-6 serum levels. The rs8192284 SNP was genotyped in 365 PSC patients, out of which 49 had developed CCA. Genotyping was performed with TaqMan Assay-on-Demand C_16170664_10 (Applied Biosystems, Foster City, CA) and the chi~2 test was used for association analyses.