DataSheet_1_mRNA vaccine with unmodified uridine induces robust type I interferon-dependent anti-tumor immunity in a melanoma model.pdf

An mRNA with unmodified nucleosides induces type I interferons (IFN-I) through the stimulation of innate immune sensors. Whether IFN-I induced by mRNA vaccine is crucial for anti-tumor immune response remains to be elucidated. In this study, we investigated the immunogenicity and anti-tumor responses of mRNA encoding tumor antigens with different degrees of N1-methylpseudouridine (m1Ψ) modification in B16 melanoma model. Our results demonstrated that ovalbumin (OVA) encoding mRNA formulated in a lipid nanoparticle (OVA-LNP) induced substantial IFN-I production and the maturation of dendritic cells (DCs) with negative correlation with increasing percentages of m1Ψ modification. In B16-OVA murine melanoma model, unmodified OVA-LNP significantly reduced tumor growth and prolonged survival, compared to OVA-LNP with m1Ψ modification. This robust anti-tumor effect correlated with the increase in intratumoral CD40+ DCs and the frequency of granzyme B+/IFN-γ+/TNF-α+ polyfunctional OVA peptide-specific CD8+ T cells. Blocking type I IFN receptor completely reversed the anti-tumor immunity of unmodified mRNA-OVA reflected in a significant decrease in OVA-specific IFN-γ secreting T cells and enrichment of PD-1+ tumor-infiltrating T cells. The robust anti-tumor effect of unmodified OVA-LNP was also observed in the lung metastatic tumor model. Finally, this mRNA vaccine was tested using B16 melanoma neoantigens (Pbk-Actn4) which resulted in delayed tumor growth. Taken together, our findings demonstrated that an unmodified mRNA vaccine induces IFN-I production or the downstream signaling cascades which plays a crucial role in inducing robust anti-tumor T cell response for controlling tumor growth and metastasis.

携带未修饰核苷的信使核糖核酸（mRNA）可通过激活天然免疫感受器诱导I型干扰素（IFN-I）产生。目前，mRNA疫苗诱导的I型干扰素是否对抗肿瘤免疫应答至关重要，仍有待阐明。本研究在B16黑色素瘤模型中，探究了携带不同程度N1-甲基假尿苷（m1Ψ）修饰的肿瘤抗原编码mRNA的免疫原性与抗肿瘤应答效果。研究结果显示，脂质纳米颗粒（LNP）包裹的卵清蛋白（OVA）编码mRNA（OVA-LNP）可诱导显著的I型干扰素产生以及树突状细胞（DCs）成熟，且该效应与m1Ψ修饰比例升高呈负相关。在B16-OVA小鼠黑色素瘤模型中，与携带m1Ψ修饰的OVA-LNP相比，未修饰的OVA-LNP可显著抑制肿瘤生长并延长小鼠生存期。该强效抗肿瘤效应与瘤内CD40阳性DCs的增多，以及颗粒酶B+/干扰素-γ+/肿瘤坏死因子-α+多功能卵清蛋白肽特异性CD8+T细胞的频率升高密切相关。阻断I型干扰素受体可完全逆转未修饰mRNA-OVA的抗肿瘤免疫效应，具体表现为卵清蛋白特异性干扰素-γ分泌型T细胞显著减少，同时PD-1阳性肿瘤浸润T细胞富集。在肺转移瘤模型中，同样观察到未修饰OVA-LNP的强效抗肿瘤效应。最后，本研究使用B16黑色素瘤新抗原（Pbk-Actn4）对该mRNA疫苗进行验证，结果可延迟肿瘤生长。综上，本研究结果表明，未修饰的mRNA疫苗可诱导I型干扰素产生或下游信号级联反应，这对于诱导强效抗肿瘤T细胞应答、进而控制肿瘤生长与转移发挥关键作用。