Aquaporin‐1 and 8 expression in the gallbladder mucosa might not be associated with the development of gallbladder stones in humans

Abstract Background Cholecystolithiasis is a highly prevalent condition in the Western world. Gallbladder stone‐related conditions represent the second most common gastrointestinal pathology. Cholesterol stones represent over 80% of gallstones. Cholesterol stones develop secondary to crystallization of bile cholesterol. Water resorption from gallbladder bile via aquaporin in the gallbladder mucosa might play a role in the development of cholesterol stones. This study investigated the expression of Aquaporin‐1 ( AQP 1) and Aquaporin‐8 ( AQP 8) in the human gallbladder mucosa and their possible association with the formation of gallbladder stones. Methods The expression of AQP 1 and AQP 8 in the gallbladder mucosa was examined via immunohistochemical staining. The expression of both AQP 1 and AQP 8 in the gallbladder mucosa of stone carriers (study group) was compared to that of nonstone carriers (control group). Results Eighty‐four gallbladder specimens from 44 male (52·2%) and 40 female (47·6%) patients were analysed. The study group included 47 specimens from stone carriers, while 37 specimens from stone‐free gallbladders were included in the control group. Immunostaining for both AQP 1 and AQP 8 was positive in 80 cases. AQP 1 was expressed both over the apical and intercellular membrane, while AQP 8 was expressed only over the apical membrane. A similar distribution was recorded in specimens from the cystic duct. Immunostaining with AQP 1 was generally stronger in comparison with AQP 8. No significant ( P > 0·05) relationship was found between aquaporin expression and the presence or absence of gallbladder stones. Conclusion AQP 1 and AQP 8 are both expressed in the gallbladder and cystic duct mucosa. However, their role in the development of gallbladder stones is still to be proven.