脂质纳米颗粒 (LNP) 封装的 mRNA 已成为刺激免疫力的有效疫苗接种工具。该技术最常见的应用是将编码抗原蛋白的 mRNA 递送至树突状细胞 (DC)，然后刺激抗原特异性淋巴细胞反应。目前尚不清楚，除了抗原呈递之外，是否可以通过 mRNA 编码的蛋白质诱导疫苗功效所需的其他免疫刺激 DC 活性。在此，我们报告了编码环状 GMP-AMP 合酶 (cGAS) 的自身 DNA 反应变体的 mRNA，称为 cGASΔN。 cGASΔN 在结合线粒体内 DNA 后产生环状二核苷酸 cGAMP。 cGAMP 与蛋白质 STING 结合，激活先天免疫反应，刺激 T 细胞。我们发现，当通过 LNP 递送至 DC 时，mRNA 编码的 cGASΔN 诱导小鼠和人类 DC 的趋化因子受体、T 细胞共刺激分子、主要组织相容性复合体蛋白、促炎细胞因子和 I 型干扰素的上调。这些活性超过了通过 LNP 传递的 mRNA 编码抗原的免疫刺激活性。用抗原-LNP 和 cGASΔN-LNP 联合免疫小鼠，导致抗原特异性产生 IFNγ 的 T 细胞大量产生。这些 T 细胞反应是持久的，并通过淋巴管、血液和肺部循环。单独使用抗原 LNP 进行免疫（类似于临床中使用的免疫接种）会刺激微弱且短暂的 T 细胞反应。与单独使用抗原 LNP 免疫相比，与 cGASΔN-LNP 共同注射时，抗体对抗原 LNP 的反应偏向 I 型同种型。这些发现确立了酶 cGASΔN 作为催化佐剂，这可能有助于增强核酸疫苗的免疫原性。重要性 核酸疫苗有望预防感染和治疗癌症。该技术最常见的用途是在 mRNA 上编码抗原蛋白，然后通过脂质纳米颗粒 (LNP) 制剂将其递送至细胞。在这项研究中，我们发现 LNP 中的 mRNA 也可以编码免疫刺激蛋白。我们发现 cGAS 酶的活性突变体（称为 cGASΔN）在 LNP 封装的 mRNA 疫苗中充当催化佐剂。通过 LNP 与抗原 mRNA-LNP 结合递送 cGASΔN mRNA，可产生持久的抗原特异性 IFNγ 产生 T 细胞，其效率超过了类似于目前临床使用的抗原 LNP 的效率。该策略不会损害 B 细胞反应；相反，它诱导了 Th1 偏向的抗体同种型。这项工作揭示了使用 mRNA 编码的催化佐剂的新疫苗设计策略，该策略可能是产生免疫疗法的 CD8 T 细胞和 B 细胞反应的理想选择。

Lipid nanoparticle (LNP)-encapsulated mRNAs have emerged as effective vaccination tools to stimulate immunity. The most common application of this technology is to deliver mRNAs that encode antigenic proteins to dendritic cells (DCs), which then stimulate antigen-specific lymphocyte responses. It is unclear whether other immunostimulatory DC activities necessary for vaccine efficacy, beyond antigen presentation, can be induced via mRNA-encoded proteins. Herein, we report an mRNA encoding a self-DNA reactive variant of the enzyme cyclic GMP-AMP synthase (cGAS), known as cGAS∆N. cGAS∆N produces the cyclic dinucleotide cGAMP upon binding intra-mitochondrial DNA. cGAMP binds the protein STING, which activates innate immune responses that stimulate T cells. We found that when delivered to DCs via LNPs, mRNA-encoded cGAS∆N induced the upregulation of chemokine receptors, T cell costimulatory molecules, major histocompatibility complex proteins, pro-inflammatory cytokines and type I interferons from murine and human DCs. These activities exceeded the immunostimulatory activities of mRNA-encoded antigens delivered via LNPs. Co-immunization of mice with antigen-LNPs and cGAS∆N-LNPs led to the robust production of antigen-specific IFNγ-producing T cells. These T cell responses were durable and circulated through the lymphatics, blood, and lungs. Immunizations with antigen-LNPs alone, akin to what are used in the clinic, stimulated weak and transient T cell responses. Antibody responses to antigen-LNPs were biased towards type I isotypes when co-injected with cGAS∆N-LNPs, as compared to immunizations with antigen-LNPs alone. These findings establish the enzyme cGAS∆N as a catalytic adjuvant, which may prove useful in enhancing the immunogenicity of nucleic acid-based vaccines. IMPORTANCE Nucleic acid-based vaccines hold promise in preventing infections and treating cancer. The most common use of this technology is to encode antigenic proteins on mRNAs that are delivered to cells via lipid nanoparticle (LNP) formulations. In this study, we discovered that immunostimulatory proteins can also be encoded on mRNAs in LNPs. We found that an active mutant of the enzyme cGAS, referred to as cGAS∆N, acts as a catalytic adjuvant in LNP-encapsulated mRNA vaccines. The delivery of cGAS∆N mRNA via LNPs in combination with antigen mRNA-LNPs led to durable antigen-specific IFNγ-producing T cells that exceeded the efficiency of antigen-LNPs similar to those currently used in the clinic. This strategy did not compromise B cell responses; rather it induced Th1-biased antibody isotypes. This work unveils new vaccine design strategies using mRNA-encoded catalytic adjuvants that could be ideal for generating CD8+ T cell and B cell responses for immunotherapies.