小鼠多亚型热休克蛋白/肽疫苗联合PD-L1免疫检查点抑制剂的抗肿瘤实验研究*

摘要

Objective: To evaluate the anti-tumor activity of mouse multi-subtype heat shock protein/peptide (mHSP/P) vaccine in combination with a programmed death ligand 1 (PD-L1) inhibitor in mouse sarcoma. Methods: Immunohistochemical staining and en-zyme-linked immunosorbent assay (Elisa) was used to quantitatively identify the expression of heat shock proteins (HSP70, HSP90, Grp94) in the sarcoma cell line MCA207. From the protein suspension prepared, mHSP/P and Grp94/peptide (Grp94/P) sarcoma vac-cines were isolated using chromatography and were identified by Western blot (WB). Flow cytometry was used to determine their cy-totoxic effects. The levels of interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α) produced upon mHSP/P and Grp94/P stimulation were measured by Elisa. The effect of sarcoma vaccines on the growth and survival of sarcoma was evaluated in mice. The expression of PD-L1 on the surface of MCA207 sarcoma cells was evaluated by immunofluorescent staining. The effect of IFN-γ treatment on the expression of PD-L1 was determined by WB. Animal experiments explored the effects of PD-L1 inhibitor in combination with mHSP/P treatment on tumors. Results: Tumor tissue carries a variety of HSP subtypes (HSP70, HSP90, Grp94). We successfully isolated sarco-ma tissue-derived mHSP/P and Grp94/P tumor vaccines, which were identified by WB; flow cytometry analysis demonstrated their cy-totoxicity. The levels of IFN-γ and TNF-α cytokines upon mHSP/P stimulation were significantly higher than that observed upon Grp94/P stimulation (P<0.05). The expression of PD-L1 on the surface of sarcoma cells increased with IFN-γ treatment. Animal experiments demonstrated that PD-L1 inhibitor in combination with mHSP/P significantly increased the immune response against tumor (P<0.05). Conclusions: Tumor-derived mHSP/P and Grp94/P can be used as tumor vaccines in animal models. The mHSP/P can elicit a stronger anti-tumor immune response than Grp94/P. IFN-γ stimulates the expression of PD-L1 in sarcoma cells, which results in immune eva-sion. The PD-L1 inhibitor in combination with mHSP/P increased the anti-tumor effect in the tumor microenvironment.%目的:应用小鼠肉瘤组织制备混合多亚型热休克蛋白/肽疫苗(mHSP/P),联合程序性死亡配体(PD-L1)抑制剂治疗小鼠肉瘤.方法:免疫组织化学染色和Elisa蛋白定量鉴定肉瘤细胞MCA207中的热休克蛋白(HSP70、HSP90、Grp94)的表达.制备蛋白悬液,通过蛋白层析技术获取mHSP/P和Grp94/肽肉瘤疫苗(Grp94/P),以Western blot(WB)鉴定.流式细胞术测定细胞毒性作用.Elisa实验测定mHSP/P和Grp94/P刺激产生的干扰素(IFN-γ)、肿瘤坏死因子(TNF-α).小鼠实验探究肉瘤疫苗对肉瘤生长以及小鼠生存状况的影响.免疫荧光染色MCA207肉瘤细胞表面PD-L1的表达,WB测定IFN-γ对PD-L1表达的影响.动物实验探究PD-L1抑制剂联合mHSP/P对肿瘤的影响.结果:肿瘤组织携带多种亚型的HSP(HSP70、HSP90、Grp94);成功制备肉瘤组织来源的mHSP/P和Grp94/P,Western blot对肿瘤疫苗鉴定并且流式细胞学测定未发现细胞毒性;制备的mHSP/P较Grp94/P刺激产生更多的IFN-γ和TNF-α细胞因子(P<0.05).肉瘤细胞表面PD-L1的表达随着IFN-γ的介入而增高;动物实验显示PD-L1抑制剂联合mHSP/P提高了免疫反应的抗肿瘤作用(P<0.05).结论:肿瘤来源的mHSP/P和Grp94/P可以作为肿瘤疫苗在动物实验中使用.mHSP/P比Grp94/P能诱发更强的抗肿瘤免疫反应.IFN-γ刺激肉瘤细胞PD-L1的表达而导致免疫逃逸.PD-L1抑制剂联合mHSP/P提高了抗肿瘤作用.