Yangyin Fuzheng Jiedu Prescription exerts anti-tumor immunity in hepatocellular carcinoma by alleviating exhausted T cells

Abstract

Background: Yangyin Fuzheng Jiedu Prescription (YFJP), a formulated Chinese herbal medicine, has been used for several decades in the treatment of hepatocellular carcinoma (HCC). Previous studies have demonstrated its anti-tumor efficacy, but the mechanism of action remains uncharacterized. This study aims to evaluate the therapeutic effect of YFJP on H22 tumor-bearing mice.

Purpose: This study aimed to evaluate the therapeutic effect of YFJP on H22 tumor-bearing mice.

Methods: A total of 50 male H22 tumor-bearing mice were randomly divided into 6 groups and continuous administered either different doses of YFJP or cyclophosphamide (CTX) or normal saline. for 2 weeks. The tumor appearance was observed by taking photos, and the tumor volume, weight, spleen and thymus index were calculated. Morphology of tumor infiltrating lymphocytes and the CD8⁺ T lymphocytes were detected through HE staining immunohistochemistry respectively. The frequency of CD3⁺, CD8⁺ T cell subsets and co-inhibitory receptors PD-1, TIGIT, Tim-3 on CD8⁺ T cell in spleen, peripheral blood and tumor tissue was performed by flow cytometry. Meanwhile, the killing and apoptotic functions of CD8⁺ T cells in tumor tissues were also detected by the same method. The levels of cytokines in peripheral blood were detected by Milliplex map mouse highs sensitivity T Cell kit. The expression of T cell transcription factor T-bet and Eomes in tumor tissues were observed by Western blot.

Results: We found that YFJP could effectively inhibit the solid tumor growth and spleen indexes, but showed little effect on the body weight in the established mouse model of HCC. Furthermore, we investigated the effect of YFJP on the phenotypic and functional changes of T cells. The results showed that YFJP could maintain the high ratio of CD3⁺ and CD8⁺ T cells in the peripheral blood, spleen, and tumor tissues while decreasing the expression of programmed cell death-1 (PD-1), T cell immunoglobulin and ITIM domain (TIGIT), T cell immunoglobulin domain and mucin domain-3 (Tim-3) in CD8⁺ T cells, respectively. Surprisingly, PD-1/Tim-3 double-positive T cells in the peripheral blood and tumor tissues were significantly decreased. Additionally, YFJP restored the cytotoxicity of tumor-infiltrating T cells and delayed their apoptosis in H22 tumor-bearing mice. In addition, treatment with YFJP significantly decreased the expression of inflammatory and immunosuppressive cytokines (including IL-1β, IL-6, and IL-10) in the serum and tumor tissues whereas enhancing that of effector cytokines TNF-α, and IFN-γ. Moreover, T cell transcription factors T-bet increased and Eomes degraded in the tumor tissues upon YFJP treatment.

Conclusion: In conclusion, these results demonstrated that YFJP could simultaneously exert anti-tumor immune response in H22 tumor-bearing mice by alleviating T cell exhaustion and immunosuppression.

Keywords: H22 tumor-bearing mice; Hepatocellular carcinoma; T cell exhaustion; Tumor microenvironment; Yangyin Fuzheng Jiedu prescription.