TLR4 and clonorchiasis: In conclusion, the present study, for the first time shows that ESP of C. sinensis can induce secretion of TNF-α but not IL-6 via TLR4 in vitro, suggesting that TLR4 which mediates pro-inflammatory responses in BECs serves as a primary component that may contribute to defenses of host against C. sinensis infection and the pathogenesis of clonorchiasis which is of significance for health of human and animal.