Hydrogel materials have emerged as versatile platforms for various biomedical applications. Notably, the engineered nanofiber-hydrogel composite (NHC) has proven effective in mimicking the soft tissue extracellular matrix, facilitating substantial recruitment of host immune cells and the formation of a local immunostimulatory microenvironment. Leveraging this feature, here we report an mRNA lipid nanoparticle (LNP)-incorporated NHC microgel matrix, termed LiNx, by incorporating LNPs loaded with mRNA encoding tumour antigens. Harnessing the high transfection efficiency of LNPs in antigen-presenting cells, LiNx demonstrates substantial levels of immune cell recruitment, antigen expression and presentation, and cellular interaction. These attributes collectively create an immunostimulating microenvironment and yield a potent immune response with a single dose at a level comparable to the conventional three-dose LNP immunization protocol. Further investigation reveals that the LiNx generates not only high levels of Th1 and Th2 responses, but also a distinct Type 17 T helper cell response critical for bolstering antitumour efficacy. Our findings elucidate the mechanism underlying LiNx's role in potentiating antigen-specific immune responses, presenting a strategy for cancer immunotherapy.
© 2025. The Author(s).

Posttranscriptional modifications are involved in cancer progression. However, the function and regulatory mechanism of mRNA acetylation modification remains largely unknown. Here, we discover an unexpected role of N4-acetylcytidine (ac4C) RNA acetyltransferase NAT10 in reshaping the tumor immune microenvironment. By analyzing patients' data, we find that NAT10 is upregulated in tumor tissues, and negatively correlated with immune cell infiltration and overall survival. Loss of tumoral NAT10 enhances tumor-specific cellular immune response and suppresses tumor growth. Mechanistically, MYC is identified as a key downstream target of NAT10 via enhancing mRNA ac4C modification. Inhibition of NAT10 blocks the MYC/CDK2/DNMT1 pathway, enhances double-stranded RNA (dsRNA) formation, which triggers type I interferon response and improves tumor specific CD8+ T cell response in vivo. More importantly, the inhibition of NAT10, using either small molecule inhibitor (Remodelin) or PEI/PC7A/siNAT10 nanoparticles, synergize PD-1 blockade in elevating anti-tumor immune response and repressing tumor progression. Our findings thus uncover the crucial role of tumor-intrinsic NAT10 in tumor immune microenvironment, which represents a promising target for enhancing cancer immunotherapy.
© 2025. The Author(s).

The mRNA lipid nanoparticles (LNPs) represent a new generation of vaccine carriers designed to elicit potent immune responses against infectious diseases and cancer. Despite the clinical success and rapid advancements in mRNA LNP technologies, the trafficking patterns of LNPs after intramuscular (i.m.) administration and the subsequent tissue-specific immunological effects have not been systematically characterized. Here, we report that trafficking of mRNA LNPs to different organs following i.m. injection is crucial for the induction of tissue-specific immunity beyond systemic immune response, particularly in tissue-resident CD8 + T cell generation, which is important for localized defense. By fine-tuning the composition of mRNA LNPs, trafficking patterns to systemic organs can be modulated, which can alter the resulting tissue-specific immune response. Formulations with a greater ability to enter the bloodstream can preferentially localize and transfect cells in specific organs like the liver, elicit stronger tissue-specific CD8 + T cell immune responses, and achieve enhanced efficacy in a liver tumor model. These findings highlight the potential to tailor mRNA LNP compositions to modulate trafficking following i.m. injection, thereby providing novel strategies for designing tissue-specific vaccines. Such strategies are particularly valuable for organ-specific diseases like cancer and infectious diseases, where tissue targeting and long-lasting immunity are essential for therapeutic success.

Personalized cancer vaccines (PCVs) largely leverage neoantigens arising from somatic mutations, limiting their application to patients with relatively high tumor mutational burden (TMB). This underscores the need for alternative antigens to design PCVs for low TMB cancers. To this end, we substantiate endogenous retroviral elements (EVEs) as tumor antigens through large-scale genomic analyses of healthy tissues and solid cancers. These analyses revealed that the breadth of EVE expression in tumors stratify checkpoint inhibitor-treated melanoma patients into groups with differential overall and progression-free survival. To enable the design of PCVs containing EVE-derived epitopes with therapeutic potential, we developed a computational pipeline, ObsERV. We show that EVE-derived peptides are presented as epitopes on tumors and can be predicted by ObsERV. Preclinical testing of ObsERV demonstrates induction of sustained poly-functional CD4+ and CD8+ T-cell responses as well as long-term tumor protection. As such, EVEs may facilitate and improve PCVs, especially for low-TMB patients.
© 2025. The Author(s).

ABSTRACT Lipid nanoparticle (LNP)-encapsulated nucleoside-modified mRNA vaccines elicit robust CD4 + T cell responses, which are essential for antiviral immunity 1–3 . While peptides presented to CD4 + T cells via major histocompatibility complex class II (MHC II) are traditionally thought to be derived from extracellular sources that are processed by antigen presenting cells (APCs) through the classical exogenous pathway 4,5 , the precise mechanisms of mRNA-LNP vaccine-specific CD4 + T cell priming remain unknown. Here, we investigated the role of alternative, endogenous antigen presentation pathways 6,7 in inducing CD4 + T cell responses to mRNA-LNP vaccines. APCs treated with mRNA-LNP vaccines were consistently superior in activating T cells under conditions of endogenous, rather than exogenous, presentation. Immunization with an mRNA-LNP vaccine that excludes antigen expression in APCs resulted in lower antigen-specific CD4 + T cell, T follicular helper cell, and antibody responses than mice receiving control vaccine. In contrast, depletion of vaccine antigen from exogenous sources such as muscle cells resulted in little to no reduction in antigen-specific CD4 + T cells. Our findings demonstrate that direct presentation of endogenous antigen on MHC II is crucial to mRNA-LNP vaccine-induced immune responses and adds to a growing body of literature that redefines the paradigm of MHC II-restricted antigen processing and presentation.