Abstract
Background/aims: Immune cells are pivotal players in the immune responses against both parasitic infection and malignancies. Substantial evidence demonstrated that there may exist possible relationship between Echinococcus granulosus (E.granulosus) infection and hepatocellular carcinoma (HCC) development. Thus, this study aimed to observe crucial roles of immune cells in the formation of subcutaneous lesions after transplanting HepG2 cell lines with or without E.granulosus protoscoleces (PSCs).Methods: HepG2 cell lines were subcutaneously injected into nude mice in the control group. In the co-transplantation group, HepG2 cells were subcutaneously co-injected with high dosage of E.granulosus PSCs. From the 25th day of transplantation, volume of subcutaneous lesions was measured every four days, which were removed at the 37th day for further studies. Basic pathological and functional changes were observed. Moreover, expression of Ki67, Bal-2, Caspase3, α-smooth muscle actin (α-SMA), T cell markers (CD3, CD4, CD8), PD1/PD-L1, nature killer (NK) cell markers (CD16, CD56) were further detected by immunohistochemistry.Results: Subcutaneous lesions were gradually increased in volume and there occurred pathologically heterogeneous tumor cells, which were more significant in the co-transplantation group. Compared to the control group, expression of proliferation markers Ki67 and Bcl-2 was at higher levels in the co-transplantation group. Reversely, apoptotic marker Caspase3 was highly detected in the control group, suggesting promoting effects of E.granulosus PSCs on HCC development. Interestingly, subcutaneous lesions of the co-transplantation group were more functional in synthesizing and storing glycogen. Collagen and α-SMA+ cells were also at higher levels in the co-transplantation group than those in the control group. Most importantly, co-transplantation of HepG2 cells with E.granulosus PSCs led to significant increase in the expression of T cell markers (CD3, CD4 and CD8), immune inhibitory checkpoint PD1/PD-L1 and NK cells markers (CD16 and CD56). Conclusions: E.granulosus may have promoting effects on HCC development, which was closely associated with the immune responses of T cells and NK cells.