HPV infection inhibits aquaporin-mediated hydrogen peroxide elimination and affects human sperm function

Aquaporins (AQPs) 3, 7, 8, and 11 are expressed in human sperm cells and are localized in the plasma membrane and in intracellular structures. AQPs are involved in cell volume regulation, cytoplasm removal during sperm maturation and ROS (H2O2) elimination. Recently, AQP-mediated H2O2 permeability was found to be reduced by oxidative stress and related to a decrease in sperm number and motility. We studied the possible effect of Human Papillomavirus (HPV) on the expression and function of AQPs in human sperm cells of patients undergoing infertile couple evaluation. ELISA experiments showed that HPV infection is associated to an increased AQPs expression in normospermic patients and to a decreased one in sub-fertile patients. Functional experiments demonstrated that HPV infection heavily reduces water permeability of sperm cells of both normospermic and sub-fertile patients. Confocal IF experiments showed colocalization of HPV L1 protein with AQP8. Docking of HPV L1 and AQP8 atomic models suggested a distant effect of L1 on the pore NPA region. Present findings suggest that HPV infection affects AQPs expression and directly inhibits their function, probably by making sperm cells more sensitive to oxidative stress