Tumour-derived IL-10 within tumour microenvironment represses the antitumour immunity of Socs1-silenced and sustained antigen expressing DCs

It has been shown that silencing of suppressor of cytokine signalling 1 (Socs1) or stably expressing transgenic protein Ags in antigen-presenting dentritic cells (DCs) strongly enhances antigen-specific anti-tumour immunity. However, whether the strong and long-lasting T cell responses induced by the modified DCs could modulate the immunosuppressive tumour microenvironment has not been clarified. In this study, we explored the anti-tumour immunity of DCs modified by Socs1-shRNA lentiviral transduction combined with sustained expression of TRP2 in different tumour models. We showed that transfer Socs1-silenced or tumour antigen TRP2 persistent expressed DCs, or DCs modified by combination of Socs1-silencing and sustaining TRP2 expression prior to inoculation of tumour cells delayed B16 tumour cell growth, prolonged mouse survival and increased the ratio of CD8+ T/Treg as well as the CTL activity in tumours. However, there was no significant effect on tumour growth and mouse survival rate upon tumour established. Further, we showed that tumour cell secreted IL-10 counteracted the immunity of modified DCs in established tumour model, injection of Socs1-shRNA and TRP2 antigen modified significantly inhibited growth of the established B16-IL-10-/− tumours. These data indicated that the high level of IL-10 within tumour microenvironment is one of factors that compromise DC vaccine functions.