Feiji Recipe And Astragaloside â…£ Influence IDO And Tumor Immune Escape

Tumor cells have developed multiple mechanisms to escape T-cell-mediated immune recognition. Indoleamine2,3-dioxygenase (IDO), a tryptophan-catabolizing enzyme inducing immune tolerance, is involved in tumor escape by tryptophan exhausting or kynurenine accumulating, it could be a new targer of cancer therapy. Astragaloside IV (AS-IV) is an monomer of Feiji Recipe, has been shown to be capable of restoring the impaired T cell functions in cancer patients. Therefore, we propose a hypothesis that’Feiji Recipe and AS-IV could down-regulate IDO so as to inhibit immune escape’, we’re going to investigate the mechanism underlying immune escape induced by IDO, and provide theoretical basis of clinical application of Feiji Recipe and AS-IV.Here, we used IDO overexpressed murine Lewis lung carcinoma (3LL) cells to establish an orthotopic lung cancer model, and showed that growth of tumor was suppressed and lifespan was prolonged by Feiji Recipe and AS-IV treatment in vivo. Feiji Recipe and AS-IV also could down-regulate regulatory T cells (Tregs) and up-regulate cytotoxic T lymphocytes (CTLs) in vivo and in vitro. Consistent with its ability to interfere with T-cell immunity, Feiji Recipe and AS-IV blocked IDO induction both in vitro and in vivo.The results of these studies indicate that Feiji Recipe and AS-IV have in vivo anticancer activity and can enhance the immune response via inhibit the Tregs frequency and induce the activity of CTLs, which might be related to the inhibition of IDO expression. Our study revealed the mechanism of Feiji Recipe and AS-IV in cancer therapy, and provide new experimental evidences of IDO targetted immunotherapy.