Pancreatobiliary reflux increases macrophage-secreted IL-8 and activates the PI3K/NFκB pathway to promote cholangiocarcinoma progression.

Background: Persistent pancreaticobiliary reflux (PBR) is associated with a high risk of biliary malignancy. This study aimed to evaluate the proportion of PBR in biliary tract diseases and mechanisms by which PBR promoted cholangiocarcinoma progression.

Methods: Overall 227 consecutive patients with primary biliary tract disease participated in this study. The amylase levels in the collected bile were analyzed. The mechanisms underlying the effect of high-amylase bile on bile duct epithelial and cholangiocarcinoma cells progression were analyzed. The source of interleukin-8 (IL-8) and its effects on the biological functions of cholangiocarcinoma cells were investigated.

Results: The bile amylase levels in 148 of 227 patients were higher than the upper serum amylase limit of 135 IU/L. PBR was significantly correlated with sex, pyrexia, and serum gamma-glutamyl transferase (GGT) levels in the patient cohort. High-amylase bile-induced DNA damage and genetic differences in the transcript levels of the gallbladder mucosa and facilitated the proliferation and migration of bile duct cancer cells (HUCCT1 and QBC939 cells). The concentration of many cytokines increased in high-amylase bile. IL-8 is secreted primarily by macrophages via the mitogen-activated protein kinase pathway and partially by bile duct epithelial cells. IL-8 promotes the progression of HUCCT1 and QBC939 cells by regulating the expression of epithelial-mesenchymal transition-associated proteins and activating the phosphatidylinositol 3-kinase/nuclear factor kappa-B pathway.

Conclusions: PBR is one of the primary causes of biliary disease. IL-8 secreted by macrophages or bile duct epithelial cells stimulated by high-amylase bile promotes cholangiocarcinoma progression.