Coinfection with Helicobacter pylori and Opisthorchis viverrini Enhances the Severity of Hepatobiliary Abnormalities in Hamsters

Abstract

Persistent infection with <i>Opisthorchis viverrini</i> causes hepatobiliary abnormalities, predisposing infected individuals to cholangiocarcinoma (CCA). In addition, <i>Helicobacter pylori</i> is highly prevalent in most countries and is a possible risk factor for CCA; however, its role in enhancing hepatobiliary abnormality is unclear. Here, we investigated the effects of coinfection with <i>H. pylori</i> and <i>O. viverrini</i> on hepatobiliary abnormality. Hamsters were divided into four groups: (i) normal, (ii) <i>H. pylori</i> infected (HP), (iii) <i>O. viverrini</i> infected (OV), and (iv) <i>O. viverrini</i> and <i>H. pylori</i> infected (OV+HP). At 6 months postinfection, PCR and immunohistochemistry were used to test for the presence of <i>H. pylori</i> in the stomach, gallbladder, and liver. In the liver, <i>H. pylori</i> was detected in the following order: OV+HP, 5 of 8 (62.5%); HP, 2 of 5 (40%); OV, 2 of 8 (25%). <i>H. pylori</i> was not detected in normal (control) liver tissues. Coinfection induced the most severe hepatobiliary abnormalities, including periductal fibrosis, cholangitis, and bile duct hyperplasia, leading to a significantly decreased survival rate of experimental animals. The greatest thickness of periductal fibrosis was associated with a significant increase in fibrogenesis markers (expression of alpha smooth muscle actin and transforming growth factor beta). Quantitative reverse transcription-PCR revealed that the highest expression levels of genes for proinflammatory cytokines (interleukin-1 [<i>IL-1</i>], <i>IL-6</i>, and tumor necrosis factor alpha) were also observed in the OV+HP group. These results suggest that coinfection with <i>H. pylori</i> and <i>O. viverrini</i> increased the severity of hepatobiliary abnormalities to a greater extent than either single infection did.