Innate immune mechanisms of mRNA vaccines

M28 family peptidase derived from Peribacillus frigoritolerans initiates trained immunity to prevent MRSA via the complosome-phosphatidylcholine axis

Methicillin-resistant Staphylococcus aureus (MRSA) represents a major global health threat due to its resistance to conventional antibiotics. The commensal microbiota maintains a symbiotic relationship with the host, playing essential roles in metabolism, energy regulation, immune modulation, and pathogen control. Mammals harbor a wide range of commensal bacteria capable of producing unique metabolites with potential therapeutic properties. This study demonstrated that M28 family peptidase (M28), derived from commensal bacteria Peribacillus frigoritolerans (P. f), provided protective effects against MRSA-induced pneumonia. M28 enhanced the phagocytosis and bactericidal activity of macrophages by inducing trained immunity. RNA sequencing and metabolomic analyses identified the CFB-C3a-C3aR-HIF-1α axis-mediated phosphatidylcholine accumulation as the key mechanism for M28-induced trained immunity. Phosphatidylcholine, like M28, also induced trained immunity. To enhance M28-mediated therapeutic potential, it was encapsulated in liposomes (M28-LNPs), which exhibited superior immune-stimulating properties compared to M28 alone. In vivo experiments revealed that M28-LNPs significantly reduced bacterial loads and lung damage following MRSA infection, which also provided enhanced protection against Klebsiella pneumoniae and Candida albicans. We first confirmed a link between complement activation and trained immunity, offering valuable insights into the treatment and prevention of complement-related autoimmune diseases.

Varicella zoster virus mRNA vaccine candidate induced superior cellular immunity and comparable humoral and Fc-mediated immunity compared to the licensed subunit vaccine in a mouse model

The threat of herpes zoster (HZ) is increasing, particularly in the elderly and immunocompromised individuals. Although two platform vaccines are currently available for HZ prevention, the low effectiveness of the live attenuated varicella-zoster virus vaccine (Zostavax®), and the high reactogenicity and limited supply of the AS01 adjuvant gE subunit vaccine (Shingrix®) indicate that, the development of more effective and safe vaccines is required. Compared to conventional vaccines, mRNA vaccines offer the advantages of faster production and generally do not require adjuvants. However, no authorized mRNA vaccine is currently available for HZ. Therefore, we aimed to prepare a gE mRNA vaccine and evaluate the immunogenicity compared with the two commercial vaccines in mice. The gE mRNA vaccine elicited a robust humoral immune response, as measured by an enzyme-linked immunosorbent assay and the fluorescent antibody to membrane antigen test. The mRNA vaccine binding antibody level was comparable to that of Shingrix® and significantly higher than that of Zostavax®. In contrast, in cellular immune responses, which were evaluated by ELISpot assays and intracellular cytokine staining assay, the VZV gE mRNA vaccine induced significantly higher responses than Zostavax® and Shingrix®. In addition, the antibody-dependent cellular phagocytosis activity of the gE mRNA vaccine was comparable to that of the commercial vaccines. However, the highest antibody-dependent cellular cytotoxicity response was achieved by Shingrix®, followed by gE mRNA and then Zostavax®. Our results demonstrate that the mRNA HZ vaccine candidate elicited robust immunogenicity, especially in cellular immunity, and shows a promising potential for HZ prevention.

Efficiency enhancement in main path extraction in mRNA vaccine field: A novel approach leveraging intermediate patents, with shielding origin and terminus patent edges

mRNA vaccines offer groundbreaking technological advantages and broad application potential. Their rapid advancement, particularly during the COVID-19 pandemic, is the result of decades of research and numerous technological breakthroughs. These discoveries build upon each other, forming dense, interconnected networks of progress. Studying the technological development paths of mRNA vaccines is therefore essential. Main path analysis (MPA) is particularly effective for mapping out development trajectories within complex and interconnected networks, which serves as a powerful tool for identifying key nodes and innovations. This study introduces a novel approach to extracting main paths from a patent citation network in the mRNA vaccine field. Initially, we shielded edges connecting the origin and terminus patents. Subsequently, we extracted the main paths from intermediate patents, and then, we reintegrated the edges connecting the origin and terminus patents based on the citation relationships, resulting in a comprehensive extraction of the main paths. The research findings indicate a consistency among the global main paths, global key-route main paths, local forward main paths, and local key-route main paths within the mRNA vaccine field. The patents on the main paths predominantly focus on nucleic acid modifications and delivery systems. The local backward main paths identify a greater number of patents, especially those related to litigation, offering a richer and more diverse set of technological insights. This study significantly advances the methodology of MPA, with the innovative shielding technique offering a fresh perspective for navigating complex networks and providing a deeper understanding of technological development in the mRNA vaccine domain.

Analytical factors for optimization of chain-length distribution analysis of mRNA using capillary gel electrophoresis

The development of mRNA vaccines against coronavirus disease-2019 has garnered attention in utilizing mRNA-based modalities such as mRNA vaccines and therapeutics. mRNA length is a crucial factor in the quality assessment of mRNA-based modalities, confirming the integrity of mRNA as an active component. Capillary gel electrophoresis is a representative analytical method used to examine mRNA chain length and should sufficiently separate full-length mRNAs and impurity RNAs (shortmers and longmers) to accurately evaluate mRNA quality. However, the analytical parameters affecting the separation of mRNAs have not been adequately verified. This study comprehensively analyzed the analytical parameters of capillary gel electrophoresis, and found that the gel concentration, denaturant, preheating treatment, capillary temperature, and fluorescent dye remarkably affect the separation of long-chain-length RNAs. The separation limits of capillary gel electrophoresis analysis were examined under adjusted analytical parameter conditions. Consequently, RNAs of approximately 4,000 nucleotides length and their defective RNAs of ≥200 nucleotides could be effectively separated. Furthermore, when RNA separation under our adjusted conditions was compared with that under the conditions recommended in the United States Pharmacopeia (USP) draft guidelines, our method demonstrated higher RNA separation for both RNA prepared in this study and that of the approved mRNA vaccine.

Comprehensive insights of etiological drivers of hepatocellular carcinoma: Fostering targeted nano delivery to anti-cancer regimes

Hepatocellular carcinoma (HCC) stands as one of the most prevalent and deadliest malignancies on a global scale. Its complex pathogenesis arises from multifactorial etiologies, including viral infections, metabolic syndromes, and environmental carcinogens, all of which drive genetic and molecular aberrations in hepatocytes. This intricate condition is associated with multiple causative factors, resulting in the abnormal activation of various cellular and molecular pathways. Given that HCC frequently manifests within the context of a compromised or cirrhotic liver, coupled with the tendency of late-stage diagnoses, the overall prognosis tends to be unfavorable. Systemic therapy, especially conventional cytotoxic drugs, generally proves ineffective. Despite advancements in therapeutic interventions, conventional treatments such as chemotherapy often exhibit limited efficacy and substantial systemic toxicity. In this context, nanomedicine, particularly lipid-based nanoparticles (LNPs), has emerged as a promising strategy for enhancing drug delivery specificity and reducing adverse effects. This review provides a comprehensive overview of the molecular and metabolic underpinnings of HCC. Furthermore, we explored the role of lipid-based nano-formulations including liposomes, solid lipid nanoparticles, and nanostructured lipid carriers in targeted drug delivery for HCC. We have highlighted recent advances in LNP-based delivery approaches, FDA-approved drugs, and surface modification strategies to improve liver-specific delivery and therapeutic efficacy. It will provide a comprehensive summary of various treatment strategies, recent clinical advances, receptor-targeting strategies and the role of lipid composition in cellular uptake. The review concludes with a critical assessment of existing challenges and future prospects in nanomedicines-driven HCC therapy.

Genetic adjuvants: A paradigm shift in vaccine development and immune modulation

The COVID-19 pandemic underscored the urgency of developing effective vaccines to combat infectious diseases, especially in vulnerable populations such as the elderly and immunocompromised. While recombinant protein vaccines offer safety, their poor immunogenicity highlights the need for advanced vaccination platforms. New genetic/nucleic acid vaccine formulations like plasmid DNA and mRNA showed efficiency and safety in preclinical and clinical studies; however, they demand innovative adjuvants because their mechanism of action differs from traditional protein vaccines. Genetic adjuvants-encoded by nucleic acids within DNA, RNA, or viral vectors-emerge as a promising solution by targeting and modulating specific immune pathways, including antigen presentation, T cell activation, and memory formation. These innovative adjuvants enhance vaccine efficacy by fine-tuning innate and adaptive immune responses, overcoming immune senescence, and addressing the challenges of CD8+ T cell activation in immunocompromised populations. This review explores the potential of genetically encoded adjuvants, including cytokines, chemokines, and other immune modulators. By comparing these adjuvants to traditional formulations, we highlight their capacity to address the limitations of modern vaccines while discussing their integration with emerging technologies like RNA-based vaccines. As genetic adjuvants advance toward clinical application, understanding their mechanisms and optimizing their delivery is pivotal to unlocking next-generation immunization strategies.

BNT162b2 mRNA vaccine elicits robust virus-specific antibodies but poor cross-protective CD8+ memory T cell responses in adolescents with type 1 diabetes

BACKGROUND

COVID-19 mRNA vaccines have demonstrated 95 % efficacy in the general population. However, their immunogenicity in adolescents with Type 1 Diabetes (T1D), who exhibit weaken immune responses, remains insufficiently explored.

METHODS

Longitudinal analysis of innate immune responses following PRR-agonists and BNT162b2 vaccine stimulations, along with S-specific antibody responses, memory T cell recall responses, and RNA-sequencing were assessed in eight T1D adolescents and 16 healthy controls at six different timepoints.

RESULTS

After BNT162b2 vaccination, T1D adolescents produced SARS-CoV-2-specific binding and neutralizing antibodies (Nabs) comparable to healthy controls. Lower pre-vaccination blood HbA1c level correlated with higher antibody responses among T1D adolescents. However, they exhibited impaired TLR9-induced B cells and the first vaccine-induced monocyte activation. These differences were supported by transcriptomic analysis, which revealed the impairment in innate immune-related signatures both before and after vaccination. One year post-second vaccination, T1D adolescents demonstrated compromised cross-protection of T cell against BA.1 compared to healthy controls, which correlated with impaired innate immune responses identified in this study.

CONCLUSION

This study reveals that while T1D adolescents vaccinated with the BNT162b2 vaccine develop robust S-specific antibodies, their cross-protective T cell responses are suboptimal.

Lipid Nanoparticle: Beyond Delivery Vehicle-Unveiling Its Immunological Adjuvant Potential

Lipid nanoparticles (LNPs) have extensively been used in drug delivery over the years, and the perspective of their significance has been well established. Latest findings have demonstrated the inherent adjuvant capacity of some specific lipid components, especially in stimulating immune compartments, which prompted the rational use of lipid-based delivery vehicles in drug R&D. In this concise review, we summarize current knowledge on the adjuvant properties of LNP, with a particular focus on the key components that mediate such effects. Specifically, we describe the vital role of ionizable lipids in triggering innate immune activation and inflammation and highlight the importance of these lipids in determining vaccine effectiveness or safety. Furthermore, the mechanisms by which LNP enhance the immune response are discussed in detail, shedding light on their potential applications in next-generation vaccine design and development. We also present compelling pre-clinical studies that serve as strong evidence for the adjuvant properties of LNP components in enhancing vaccine immunogenicity.

Research progress on immune mechanism and control strategy of dsRNA impurities in mRNA vaccine

INTRODUCTION

Double-stranded RNA (dsRNA) is a key impurities of mRNA vaccines prepared by in vitro transcription (IVT) and is primarily transcribed by T7 RNA polymerase. It can trigger innate immunity and induce a series of side effects that may influence the safety of mRNA vaccines.

AREAS COVERED

This manuscript summarizes dsRNA generation mechanisms and immunity activation and analyzes the current challenges in dsRNA detection and control strategies. Regulatory standards for dsRNA impurities in mRNA vaccines have also been discussed.

EXPERT OPINION

dsRNA as a critical quality attribute (CQA), the structural heterogeneity of it (including length and structure) and its precise immunomodulatory mechanisms affecting vaccine safety are poorly understood. Regulatory authorities have not released specific standards for dsRNA. Additionally, there is a lack of comparative analysis data on different corporate testing methods. Therefore, to ensure the safety of dsRNA containing mRNA vaccines, and improve mRNA-based platforms, it is of great significance to establish standardized detection methods and standards for dsRNA; to design mRNA production with low dsRNA impurities by adopting the quality by design (QbD) approach; and to evaluate the immune stimulation mechanism of dsRNA impurities in mRNA vaccines.

Breaking the immune desert: Strategies for overcoming the immunological challenges of pancreatic cancer

Pancreatic cancer is characterised by its highly aggressive nature and extremely poor prognosis, with a uniquely complex tumour immune microenvironment that manifests as a prototypical "immune desert." This immune-desert phenotype primarily arises from the inherently low immunogenicity of the tumour, the formation of a dense fibrotic stroma, severe deficiency in immune cell infiltration, and profound immunosuppressive effects of the metabolic landscape. Specifically, dysregulated tryptophan metabolism, such as indoleamine 2,3-dioxygenase (IDO)-mediated catabolism, and excessive lactate accumulation contribute to impaired T-cell functionality. Collectively, these factors severely limit the efficacy of current immunotherapy strategies, particularly those based on immune checkpoint inhibitors, which have demonstrated significantly lower clinical response rates in pancreatic cancer than in other malignancies. In response to these therapeutic challenges, this review explores integrated treatment strategies that combine metabolic reprogramming, tumour microenvironment remodelling, and next-generation immune checkpoint blockades, such as LAG-3, TIM-3, and VISTA. These emerging approaches hold substantial promise for clinical application. For example, targeting key metabolic pathways, including glycolysis (Warburg effect) and glutamine metabolism, may help restore T-cell activity by alleviating metabolic stress within the tumour milieu. Additionally, localised administration of immune stimulators such as interleukin-12 (IL-12) and CD40 agonists may enhance immune cell infiltration and promote tumour-specific immune activation. Future research should prioritise large-scale, multicentre clinical trials to validate the therapeutic efficacy of these innovative strategies, aiming to achieve meaningful breakthroughs in pancreatic cancer immunotherapy and significantly improve long-term survival and clinical outcomes in affected patients.

Synthetic Bacterial Membrane Vesicles as Versatile Antigen-Display Platforms against Respiratory Syncytial Virus

Bacterial outer membrane vesicles (OMV) hold promise as vaccine platforms due to their natural adjuvant properties and nanoscale dimensions. However, their inherent inflammatory properties can induce excessive immune reactions, potentially harming the host, while their variability in size and low yield pose challenges for large-scale applications. To address these challenges, we developed synthetic bacterial vesicles (SyBV) through bacterial cell lysis followed by detergent treatment and sonication to eliminate nucleic acids, producing high-purity vesicles with minimal cytoplasmic residue. SyBV triggered comparable antigen-specific adaptive immunity but avoided strong inflammatory responses. We engineered SyBV to display the prefusion F protein (preF) of respiratory syncytial virus (RSV) with cytotoxic lysin A (ClyA). This approach effectively induced preF-specific antibodies and robust immune responses. Our findings suggest that SyBV could provide a safer, more efficient vaccine platform for preventing viral infections, overcoming the limitations associated with traditional OMV while preserving immunogenicity.

Evaluation of mRNA Transfection Reagents for mRNA Delivery and Vaccine Efficacy via Intramuscular Injection in Mice

The selection of an effective delivery carrier is crucial to assessing mRNA-based vaccines and therapeutics in vivo. Although lipid nanoparticles (LNPs) are commonly used for mRNA delivery, the LNP-mRNA formulation process is laborious and time-consuming and requires a high-cost microfluidic device. Instead, mixing with commercial reagents may simplify mRNA transfection into cells. However, their potential as in vivo carriers in intramuscular vaccination in mouse models remains unclear. In this study, we used three types of commercial RNA transfection reagents, MessengerMAX (MAX; liposome), TransIT-mRNA (IT; cationic polymer), and Invivofectamine (IVF; LNP), to produce nanoparticles directly by pipetting. The particle characteristics and mRNA delivery efficacy of the mRNA-transfection reagent mixtures were analyzed. Additionally, immune responses to vaccine efficacy and protective immunity of the mRNA mixtures as vaccine antigens were evaluated in a mouse model. Although MAX and IT showed high in vitro transfection efficiencies, their in vivo performances were limited. In contrast, IVF exhibited notable particle stability and homogeneity, making it a promising delivery carrier. Intramuscular IVF injection significantly enhanced both innate and adaptive immune responses with a robust systemic protein expression. Notably, when using SARS-CoV-2 Spike mRNA, IVF showed robust humoral immune responses, including production of IgG and neutralizing antibodies, thereby resulting in complete protection against SARS-CoV-2 infection. Therefore, these findings position IVF as an accessible and efficient mRNA carrier for evaluating mRNA vaccines and therapeutic efficacy in basic research.

Highly pure mRNA vaccine provides robust immunization against P. aeruginosa by minimizing type I interferon responses

Developing effective vaccines against bacteria is critical given the growing threat of antimicrobial resistance (AMR). In this study, we developed mRNA vaccines targeting Pseudomonas aeruginosa (P. aeruginosa), a key AMR pathogen, using PureCap mRNA encapsulated in lipid nanoparticles (LNPs). The PureCap technology offers a facile method for removing immunostimulatory impurities from in vitro transcribed mRNA, such as uncapped RNA and double-stranded RNA (dsRNA). Following intramuscular vaccination of mice with mRNA encoding a model antigen, PureCap mRNA elicited antibody titers that were 26-fold higher than those induced by conventional ARCA-capped mRNA. Mechanistic analyses revealed that both uncapped RNA and dsRNA impurities in ARCA-capped mRNA were responsible for the reduced humoral immune responses. While PureCap mRNA enhanced protein expression efficiency and reduced pro-inflammatory responses compared to ARCA-capped mRNA, minimizing pro-inflammatory responses was particularly critical. When anti-interferon-α/β receptor antibodies were administered, antibody responses to ARCA-capped mRNA vaccination were restored to levels comparable to those achieved with PureCap mRNA vaccination, highlighting the negative impact of type I interferon responses on antibody responses following vaccination with ARCA-capped mRNA. In a vaccination targeting the PcrV protein of P. aeruginosa, PureCap mRNA, but not ARCA-capped mRNA, significantly prolonged the survival of mice following bacterial challenges, presumably due to enhanced antibody production. Furthermore, PureCap mRNA vaccination significantly reduced bacterial loads in the lungs and mitigated tissue damage, edema, and inflammatory responses. These findings underscore the potential of PureCap mRNA as a promising platform for bacterial vaccination, offering a valuable strategy to combat AMR.

Biochemical and hematological reference intervals in rhesus and cynomolgus macaques and implications for vaccine and drug development

Nonhuman primates have a key role in the evaluation of novel therapeutics including vaccine and drug development. Monitoring biochemical and hematological parameters of macaques is critical to understand toxicity and safety, but general reference intervals following standardized guidelines remain to be determined. Here we compiled multiple internal datasets to define normal ranges of classical biochemical and hematological parameters in Indian and Chinese rhesus macaques as well as cynomolgus macaques. Furthermore, the combination of hematological data with phenotypic information of cells obtained by flow cytometry enabled analyses of specific immune cell subsets. We found that vaccination generally induced transient changes at 24 h in cell frequencies accompanied by fluctuation in selected liver enzymes and metabolites. However, most parameters remained within our identified reference intervals. These deviations did not lead to noticeable side effects. Fluctuation in selected biochemical and hematological parameters was accompanied with differentiation of CD14+CD16+ intermediate monocytes and upregulation of genes associated with interleukin-1 signaling. By contrast, two animals with noticeable side effects showed sustained deviations. This study provides insights into baseline and vaccine-induced biochemical and hematological profiles of healthy macaques, facilitating the interpretation of toxicity and safety assessments in preclinical trials of novel therapies.

Surfactant protein B-derived peptides as endosomal escape enhancers for pulmonary delivery of siRNA

Respiratory diseases still cause significant mortality and morbidity worldwide, highlighting the need for new inhalable drugs. RNA therapeutics, which have the potential to modulate the expression of virtually any gene, could address this unmet medical need. Nevertheless, clinical translation requires the design of RNA formulations able to overcome the extra- and intracellular barriers in the lung. We previously discovered that the endogenous cationic amphiphilic surfactant protein B (SP-B) promotes cytosolic delivery of small interfering RNA (siRNA) in lung-related cell types via endosomal membrane fusion. However, to bypass drawbacks related to the use of animal-derived SP-B, there is a keen interest in developing synthetic SP-B analogues with comparable activity. Here, we show that native SP-B can successfully be replaced by smaller peptides, with the N-terminal heptapeptide and amphipathic helix being minimally required to promote siRNA-induced gene silencing. Peptidolipid-coated nanogels were designed and demonstrated equivalent siRNA delivery efficacy compared to state-of-the-art lipid nanoparticles (LNPs). Moreover, they exhibit enhanced resistance to vibrating mesh nebulization and reduced inflammatory activation of bronchial epithelial cells. Collectively, the discovery of SP-B peptides as RNA delivery enhancers holds promise for developing potent inhalable RNA formulations with favorable safety profiles, of value for the treatment of chronic inflammatory pathologies.

Impact of pre-existing anti-polyethylene glycol (PEG) IgM on biodistribution and humoral response of intramuscularly administered PEGylated mRNA loaded lipid nanoparticle

With the approval of mRNA vaccines for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), lipid nanoparticles (LNP) have emerged as a powerful tool for nucleic acid delivery. Modification of LNP with polyethylene glycol (PEG)-lipids contributes to their in vitro and in vivo stability by reducing aggregation of the particles. Despite the general acknowledgement of the low immunogenicity of PEG, there are numerous reports of the occurrence of anti-PEG antibodies in the blood of healthy individuals. Furthermore, there are reports that pre-existing anti-PEG IgM antibodies attenuated the efficacy of PEG-modified drugs administered systemically. Skeletal muscles, the administration site for mRNA vaccines, are highly vascularized by a network of blood vessels to provide them with nutrients and oxygen. Since skeletal muscles can contain circulating anti-PEG antibodies or the administered mRNA-LNP extravasate into bloodstream, the purpose of this study was to evaluate the effects of pre-existing anti-PEG IgM on the protein translation, biodistribution, and humoral responses to mRNA-loaded LNP (mRNA-LNP) administered intramuscularly (i.m.) in mice. We found that the presence of anti-PEG IgM in blood has only a minor effect on the translation and distribution of mRNA-LNP in the localized muscle area where the mRNA-LNP were administered. Circulating anti-PEG IgM did not increase the total accumulation of mRNA-LNP in the liver, but did markedly diminish its protein translation because the mRNA-LNP were delivered primarily to Kupffer cells rather than to hepatocytes. Binding of anti-PEG IgM to mRNA-LNP, and subsequent complement activation, suppressed mRNA translation loaded in LNP in the liver. Repeated intramuscular injections of SARS-CoV-2 Spike protein mRNA-LNP elicited a robust immune response. Our results indicate that the presence of circulating anti-PEG IgM does not interfere with the efficiency of mRNA vaccines administered i.m. in mice. We can speculate that non-specific translation of mRNA vaccines in somatic cells may be inhibited in vivo by circulating anti-PEG IgM, reducing adverse effects such as hepatitis and myocarditis that are caused by immune responses against translated antigen proteins.

An Industry Perspective on the Use of Novel Excipients in Lipid Nanoparticles-Nonclinical Considerations

Nucleic acid drug delivery with lipid nanoparticle (LNP) formulations has enabled the development of novel therapeutics and vaccines. LNP formulations are composed of both naturally occurring and synthetic lipid excipients. This perspective shares current practices in the nonclinical safety assessment of novel lipid excipients contained in LNP formulations and identifies gaps in current regulatory guidance on this topic. There is no globally harmonized regulatory guidance for the nonclinical safety assessment of novel excipients or guidance specific to safety testing of novel excipients in LNPs. Given the complexity of these LNP formulations, most nonclinical safety studies to support development are conducted with the drug product or with a LNP that contains non-active cargo. Three case studies (Onpattro®, Comirnaty®, and SpikeVax®) highlight that specific assessments may differ depending on the encapsulated modality, the intended use (e.g., therapeutic versus preventative vaccine), dose, and frequency of dosing. These case studies also suggest that regulatory agencies are open to scientific rationale to justify why certain tests should or should not be performed. As more products are approved, it will be important to understand how precedents set for approved products can be leveraged and what additional unique strategies may be applied to ensure nonclinical safety assessments are predictive, relevant, and meaningful for human safety. Proactive alignment with regulatory authorities will be critical in this context, especially as new approaches are proposed. Guidance documents may need to be revised or created as more experience is acquired to reflect the unique considerations for these novel excipients.

Re-adenylation by TENT5A enhances efficacy of SARS-CoV-2 mRNA vaccines

Despite the widespread use of mRNA vaccines against COVID-19, little is known about the metabolism of therapeutic RNAs. Here we use nanopore sequencing1-3 to analyse individual therapeutic mRNA molecules, focusing on their poly(A) tails. We show that the Moderna mRNA-1273 vaccine4 has a poly(A) tail of around 100 nucleotides, followed by an mΨCmΨAG sequence. In cell lines, mRNA-1273 undergoes rapid degradation initiated by mΨCmΨAG removal, followed by CCR4-NOT-mediated deadenylation. However, in medically relevant preclinical models, particularly in macrophages, mRNA-1273 poly(A) tails are extended to up to 200 nucleotides by the TENT5A poly(A) polymerase5-7, which is induced by the vaccine. Re-adenylation, which stabilizes target mRNAs, is consistently observed in synthetic mRNAs that encode proteins targeted to the endoplasmic reticulum, such as ovalbumin or antigens from Zika virus8 or the malaria parasite9. The extent of re-adenylation varies: the BioNTech-Pfizer BNT162b2 vaccine10 shows less potent re-adenylation than mRNA-1273, which correlates with a smaller proportion of membrane-associated BNT162b2. This highlights the crucial role of spatial accessibility to ER-resident TENT5A in determining re-adenylation efficiency. In vivo, TENT5A is expressed in immune cells that take up mRNA vaccine, and TENT5A deficiency reduces specific immunoglobulin production for mRNA vaccines after immunization in mice. Overall, our findings reveal a principle for enhancing the efficacy of therapeutic mRNAs, paving the way for improvement.

mRNA-based vaccines and therapies - a revolutionary approach for conquering fast-spreading infections and other clinical applications: a review

Since the beginning of the COVID-19 pandemic, the development of messenger RNA (mRNA) vaccines has made significant progress in the pharmaceutical industry. The two COVID-19 mRNA vaccines from Moderna and Pfizer/BioNTech have been approved for marketing and have made significant contributions to preventing the spread of SARS-CoV-2. In addition, mRNA therapy has brought hope to some diseases that do not have specific treatment methods or are difficult to treat, such as the Zika virus and influenza virus infections, as well as the prevention and treatment of tumors. With the rapid development of in vitro transcription (IVT) technology, delivery systems, and adjuvants, mRNA therapy has also been applied to hereditary diseases such as Fabry's disease. This article reviews the recent development of mRNA vaccines for structural modification, treatment and prevention of different diseases; delivery carriers and adjuvants; and routes of administration to promote the clinical application of mRNA therapies.

Considerations for mRNA Product Development, Regulation and Deployment Across the Lifecycle

With the successful deployment of several mRNA vaccines against SARS-CoV-2, an mRNA vaccine against RSV (respiratory syncytial virus) and a large pipeline of mRNA products against other infectious diseases, cancers and rare diseases, it is important to examine the whole product lifecycle. mRNA technology enables product design, testing and manufacturing systems to be rapidly developed, but these advantages can be lost if other factors that determine public access are not closely considered. This review analyzes key aspects of the mRNA product lifecycle including candidate design, manufacturing, quality systems and product safety and storage. Regulatory thinking is well advanced in some countries but not others, but more thought on the regulation of mRNA vaccines outside of a pandemic situation as well as mRNA therapeutics including individual neoantigen therapies and rare disease treatments is needed. Consumer acceptance-the "social license to operate" around mRNA products-is critical for their uptake, particularly outside of a pandemic.

Cell-Based Therapeutic Strategies for Autoimmune Diseases

Currently, the management of autoimmune disorders still being a challenge in terms of safety, efficiency, and specificity. Cell-based therapeutic strategies have emerged as a novel approach for autoimmune disease treatment, employing different cell therapy platforms, including tolerogenic dendritic cells, regulatory T cells, conventional and regulatory chimeric antigen receptor-T cells, mesenchymal and hematopoietic stem cells, each with their biological features. Here, we discuss the different cell therapy platforms, their immunological mechanisms of action, their therapeutic potential and benefits in autoimmune diseases, and challenges related to their production, scaling up, risks, and patient safety.

TLR7-Adjuvanted Ionizable Lipid Nanoparticles for mRNA Vaccine Delivery

Ionizable lipid nanoparticles (LNPs) are clinically relevant non-viral vectors that allow intracellular delivery of mRNA vaccines to immune cells. To fight against notorious pathogens and cancer, mRNA vaccines necessitate the addition of an adjuvant to induce strong and durable cell-mediated immune responses. Adjuvants that stimulate Toll-like receptor 7 (TLR7) induce the secretion of type I interferons and proinflammatory cytokines, vital for generating strong immune responses. However, the intracellular delivery of TLR7 adjuvants to precisely stimulate the endosomal TLR7 receptor remains a huge challenge. This issue can be addressed by exploiting ionizable LNP platforms, which can encapsulate and carry mRNA vaccines and small molecule hydrophobic adjuvants to immune cells. CL347 is a potent lipid-based adjuvant that selectively stimulates the TLR7 receptor. In this study, we developed ionizable LNPs incorporating SM102 and CL347 adjuvant as the ionizable lipid and TLR7 adjuvant, respectively. CL347-SM102 LNPs exhibited particle sizes of less than 150 nm with spherical morphology and mRNA encapsulation efficiency of greater than 95%. In vivo studies showed a two-fold increase in IFN-γ producing CD4 and CD8 T cells in the lymphoid organs of the mice immunized with adjuvanted LNPs compared to the non-adjuvanted LNPs. Human PBMCs treated with adjuvanted LNPs exhibited significantly higher CD40 expression and pro-inflammatory cytokine (IL-6 and IFN-γ) secretion than non-adjuvanted LNPs. Together, these results suggest the potential of ionizable LNPs as a platform for concurrent delivery of mRNA and adjuvants for prophylactic and therapeutic vaccine applications.

Beyond the Pandemic Era: Recent Advances and Efficacy of SARS-CoV-2 Vaccines Against Emerging Variants of Concern

Vaccination has been instrumental in curbing the transmission of SARS-CoV-2 and mitigating the severity of clinical manifestations associated with COVID-19. Numerous COVID-19 vaccines have been developed to this effect, including BioNTech-Pfizer and Moderna's mRNA vaccines, as well as adenovirus vector-based vaccines such as Oxford-AstraZeneca. However, the emergence of new variants and subvariants of SARS-CoV-2, characterized by enhanced transmissibility and immune evasion, poses significant challenges to the efficacy of current vaccination strategies. In this review, we aim to comprehensively outline the landscape of emerging SARS-CoV-2 variants of concern (VOCs) and sub-lineages that have recently surfaced in the post-pandemic years. We assess the effectiveness of existing vaccines, including their booster doses, against these emerging variants and subvariants, such as BA.2-derived sub-lineages, XBB sub-lineages, and BA.2.86 (Pirola). Furthermore, we discuss the latest advancements in vaccine technology, including multivalent and pan-coronavirus approaches, along with the development of several next-generation coronavirus vaccines, such as exosome-based, virus-like particle (VLP), mucosal, and nanomaterial-based vaccines. Finally, we highlight the key challenges and critical areas for future research to address the evolving threat of SARS-CoV-2 subvariants and to develop strategies for combating the emergence of new viral threats, thereby improving preparedness for future pandemics.

Enhancing vaccine stability in transdermal microneedle platforms

Micron-scale needles, so-called microneedles (MNs) offer a minimally invasive, nearly painless, and user-friendly method for effective intradermal immunization. Maintaining the stability of antigens and therapeutics is the primary challenge in producing vaccine or drug-loaded MNs. The manufacturing of MNs patches involves processes at ambient or higher temperatures and various physio-mechanical stresses that can impact the therapeutic efficacy of sensitive biologics or vaccines. Therefore, it is crucial to develop techniques that safeguard vaccines and other biological payloads within MNs. Despite growing research interest in deploying MNs as an efficient tool for delivering vaccines, there is no comprehensive review that integrates the strategies and efforts to preserve the thermostability of vaccine payloads to ensure compatibility with MNs fabrication. The discussion delves into various physical and chemical approaches for stabilizing antigens in vaccine formulations, which are subsequently integrated into the MNs matrix. The primary focus is to comprehensively examine the challenges associated with the translation of thermostable vaccine MNs for clinical applications while considering a safe, cost-effective approach with a regulatory roadmap. The recent cutting-edge advances facilitating flexible and scalable manufacturing of stabilized MNs patches have been emphasized. In conclusion, the ability to stabilize vaccines and therapeutics for MNs applications could bolster the effectiveness, safety and user-compliance for various drugs and vaccines, potentially offering a substantial impact on global public health.

Preliminary results and a theoretical perspective of co‑treatment using a miR‑93‑5p mimic and aged garlic extract to inhibit the expression of the pro‑inflammatory interleukin‑8 gene

The coronavirus disease-19 (COVID-19) pandemic has been a very significant health issue in the period between 2020 and 2023, forcing research to characterize severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequences and to develop novel therapeutic approaches. Interleukin-6 (IL-6) and IL-8 are considered significant therapeutic targets for COVID-19 and emerging evidence has suggested that microRNAs (miRNAs/miRs) serve a key role in regulating these genes. MiRNAs are short, 19-25 nucleotides in length, non-coding RNAs that regulate gene expression at the post-transcriptional level through the sequence-selective recognition of the 3'-untranslated region (3'-UTR) of the regulated mRNAs, eventually repressing translation, commonly, via mRNA degradation. For example, among several miRNAs involved in the regulation of the COVID-19 'cytokine storm', miR-93-5p can inhibit IL-8 gene expression by directly targeting the 3'-UTR of IL-8 mRNA. In addition, miR-93-5p can regulate Toll-like receptor-4 (TLR4) and interleukin-1 receptor-associated kinase 4 (IRAK4) expression, thus affecting the nuclear factor-κB (NF-κB) pathway and the expression of NF-κB-regulated genes, such as IL-6, IL-1β and other hyper-expressed genes during the COVID-19 'cytokine storm'. In the present study, the results provided preliminary evidence suggesting that the miR-93-5p-based miRNA therapeutics could be combined with the anti-inflammatory aged garlic extract (AGE) to more effectively inhibit IL-8 gene expression. The human bronchial epithelial IB3-1 cell line was employed as experimental model system. IB3-1 cells were stimulated with the BNT162b2 COVID-19 vaccine and transfected with pre-miR-93-5p in the absence or in the presence of AGE, to verify the inhibitory effects on the BNT162b2-induced expression of the IL-8 gene. The accumulation of IL-8 mRNA was assessed by RT-qPCR; the release of IL-8 protein was determined by Bio-Plex assay. In addition, the possible applications of TLR4/NF-κB inhibitory agents (such as miR-93-5p and AGE) for treating human pathologies at a hyperinflammatory state, such as COVID-19, cystic fibrosis and other respiratory diseases, were summarized.

Persistent epigenetic memory of SARS-CoV-2 mRNA vaccination in monocyte-derived macrophages

Immune memory plays a critical role in the development of durable antimicrobial immune responses. How precisely mRNA vaccines train innate immune cells to shape protective host defense mechanisms remains unknown. Here we show that SARS-CoV-2 mRNA vaccination significantly establishes histone H3 lysine 27 acetylation (H3K27ac) at promoters of human monocyte-derived macrophages, suggesting epigenetic memory. However, we found that two consecutive vaccinations were required for the persistence of H3K27ac, which matched with pro-inflammatory innate immune-associated transcriptional changes and antigen-mediated cytokine secretion. H3K27ac at promoter regions were preserved for six months and a single mRNA booster vaccine potently restored their levels and release of macrophage-derived cytokines. Interestingly, we found that H3K27ac at promoters is enriched for G-quadruplex DNA secondary structure-forming sequences in macrophage-derived nucleosome-depleted regions, linking epigenetic memory to nucleic acid structure. Collectively, these findings reveal that mRNA vaccines induce a highly dynamic and persistent training of innate immune cells enabling a sustained pro-inflammatory immune response.

[Platform technologies in vaccine development]

Platform technologies in the narrower sense refer to approaches to vaccine development in which the vaccine is always based on a consistently identical framework and differs only in terms of the antigen. One advantage of platform technologies is their rapid adaptability for the development of a vaccine against novel pathogens or variants. Currently approved vaccines in the EU use viral vectors and mRNA as platforms. Recombinant adenoviruses (Ad), vesicular stomatitis virus (VSV), and modified vaccinia virus Ankara (MVA) serve as viral vectors. The application of mRNA-based vaccines is carried out in the form of lipid nanoparticles (LNPs). The function of the LNPs is to protect the mRNA from degradation, promote the uptake of the mRNA into the cells, and provide an adjuvant effect.

CircRNAs in Colorectal Cancer: Unveiling Their Roles and Exploring Therapeutic Potential

Colorectal cancer (CRC) is the most common malignancy of the digestive system. Although research into the causes of CRC's origin and progression has advanced over the past few decades, many details are still not fully understood. Circular RNAs (circRNAs), as a novel regulatory molecule, have been found to be closely involved in various key biological processes in CRC. CircRNAs also have been shown to encode proteins, which could offer new possibilities for therapeutic applications. This ability to produce tumor-specific proteins makes circRNA-based vaccines a potentially valuable approach for targeted cancer treatment. In this review, we summarize recent findings on the various roles of circRNAs in CRC and explore their potential in the development of protein-encoding circRNA vaccines for CRC therapy.

Expanded Spectrum and Increased Incidence of Adverse Events Linked to COVID-19 Genetic Vaccines: New Concepts on Prophylactic Immuno-Gene Therapy, Iatrogenic Orphan Disease, and Platform-Inherent Challenges

The mRNA- and DNA-based "genetic" COVID-19 vaccines can induce a broad range of adverse events (AEs), with statistics showing significant variation depending on the timing and data analysis methods used. Focusing only on lipid nanoparticle-enclosed mRNA (mRNA-LNP) vaccines, this review traces the evolution of statistical conclusions on the prevalence of AEs and incidents associated with these vaccines, from initial underestimation of atypical, severe toxicities to recent claims suggesting the possible contribution of COVID-19 vaccinations to the excess deaths observed in many countries over the past few years. Among hundreds of different AEs listed in Pfizer's pharmacovigilance survey, the present analysis categorizes the main symptoms according to organ systems, with nearly all of them being affected. Using data from the US Vaccine Adverse Event Reporting System and a global vaccination dataset, a comparison of the prevalence and incidence rates of AEs induced by genetic versus flu vaccines revealed an average 26-fold increase in AEs with the use of genetic vaccines. The difference is especially pronounced in the case of severe 'Brighton-listed' AEs, which are also observed in COVID-19 and post-COVID conditions. Among these, the increases in incidence rates relative to flu vaccines, given as x-fold rises, were 1152x, 455x, 226x, 218x, 162x, 152x, and 131x for myocarditis, thrombosis, death, myocardial infarction, tachycardia, dyspnea, and hypertension, respectively. The review delineates the concept that genetic vaccines can be regarded as prophylactic immuno-gene therapies and that the observed chronic disabling AEs might be categorized as iatrogenic orphan diseases. It also examines the unique vaccine characteristics that could be causally related to abnormal immune responses which potentially lead to adverse events and complications. These new insights may contribute to improving the safety of this platform technology and assessing the risk/benefit balance of various products.

Role of T Follicular Helper Cells in Viral Infections and Vaccine Design

T follicular helper (Tfh) cells are a specialized subset of CD4+ T lymphocytes that are essential for the development of long-lasting humoral immunity. Tfh cells facilitate B lymphocyte maturation, promote germinal center formation, and drive high-affinity antibody production. Our current knowledge of Tfh interactions with the humoral immune system effectors suggests that they have a critical role in supporting the immune response against viral infections. This review discusses the mechanisms through which Tfh cells influence anti-viral immunity, highlighting their interactions with B cells and their impact on antibody quality and quantity. We explore the role of Tfh cells in viral infections and examine how vaccine design can be improved to enhance Tfh cell responses. Innovative vaccine platforms, such as mRNA vaccines and self-assembling protein nanoplatforms (SAPNs), are promising strategies to enhance Tfh cell activation. Their integration and synergistic combination could further enhance immunity and Tfh responses (SAPN-RNA vaccines). In summary, we provide a comprehensive overview of the current insights into Tfh cells' role during viral infections, emphasizing their potential as strategic targets for innovative vaccine development.

In Vivo Engineered CAR-T Cell Therapy: Lessons Built from COVID-19 mRNA Vaccines

Chimeric antigen receptor T cell (CAR-T) therapy has revolutionized cancer immunotherapy but continues to face significant challenges that limit its broader application, such as antigen targeting, the tumor microenvironment, and cell persistence, especially in solid tumors. Meanwhile, the global implementation of mRNA vaccines during the COVID-19 pandemic has highlighted the transformative potential of mRNA and lipid nanoparticle (LNP) technologies. These innovations, characterized by their swift development timelines, precise antigen design, and efficient delivery mechanisms, provide a promising framework to address some limitations of CAR-T therapy. Recent advancements, including mRNA-based CAR engineering and optimized LNP delivery, have demonstrated the capacity to enhance CAR-T efficacy, particularly in the context of solid tumors. This review explores how mRNA-LNP technology can drive the development of in vivo engineered CAR-T therapies to address current limitations and discusses future directions, including advancements in mRNA design, LNP optimization, and strategies for improving in vivo CAR-T functionality and safety. By bridging these technological insights, CAR-T therapy may evolve into a versatile and accessible treatment paradigm across diverse oncological landscapes.

Generation of tolerogenic antigen-presenting cells in vivo via the delivery of mRNA encoding PDL1 within lipid nanoparticles

Tolerogenic antigen-presenting cells (APCs) are promising as therapeutics for suppressing T cell activation in autoimmune diseases. However, the isolation and ex vivo manipulation of autologous APCs is costly, and the process is customized for each patient. Here we show that tolerogenic APCs can be generated in vivo by delivering, via lipid nanoparticles, messenger RNA coding for the inhibitory protein programmed death ligand 1. We optimized a lipid-nanoparticle formulation to minimize its immunogenicity by reducing the molar ratio of nitrogen atoms on the ionizable lipid and the phosphate groups on the encapsulated mRNA. In mouse models of rheumatoid arthritis and ulcerative colitis, subcutaneous delivery of nanoparticles encapsulating mRNA encoding programmed death ligand 1 reduced the fraction of activated T cells, promoted the induction of regulatory T cells and effectively prevented disease progression. The method may allow for the engineering of APCs that target specific autoantigens or that integrate additional inhibitory molecules.

The immunogenic potential of an optimized mRNA lipid nanoparticle formulation carrying sequences from virus and protozoan antigens

BACKGROUND

Lipid nanoparticles (LNP) are a safe and effective messenger RNA (mRNA) delivery system for vaccine applications, as shown by the COVID-19 mRNA vaccines. One of the main challenges faced during the development of these vaccines is the production of new and versatile LNP formulations capable of efficient encapsulation and delivery to cells in vivo. This study aimed to develop a new mRNA vaccine formulation that could potentially be used against existing diseases as well as those caused by pathogens that emerge every year.

RESULTS

Using firefly luciferase (Luc) as a reporter mRNA, we evaluated the physical-chemical properties, stability, and biodistribution of an LNP-mRNA formulation produced using a novel lipid composition and a microfluidic organic-aqueous precipitation method. Using mRNAs encoding a dengue virus or a Leishmania infantum antigen, we evaluated the immunogenicity of LNP-mRNA formulations and compared them with the immunization with the corresponding recombinant protein or plasmid-encoded antigens. For all tested LNP-mRNAs, mRNA encapsulation efficiency was higher than 85%, their diameter was around 100 nm, and their polydispersity index was less than 0.3. Following an intramuscular injection of 10 µg of the LNP-Luc formulation in mice, we detected luciferase activity in the injection site, as well as in the liver and spleen, as early as 6 h post-administration. LNPs containing mRNA encoding virus and parasite antigens were highly immunogenic, as shown by levels of antigen-specific IgG antibody as well as IFN-γ production by splenocytes of immunized animals that were similar to the levels that resulted from immunization with the corresponding recombinant protein or plasmid DNA.

CONCLUSIONS

Altogether, these results indicate that these novel LNP-mRNA formulations are highly immunogenic and may be used as novel vaccine candidates for different infectious diseases.

Lipid Nanoparticles for mRNA Delivery in Cancer Immunotherapy

Cancer immunotherapy is poised to be one of the major modalities for cancer treatment. Messenger RNA (mRNA) has emerged as a versatile and promising platform for the development of effective cancer immunotherapy. Delivery systems for mRNA therapeutics are pivotal for their optimal therapeutic efficacy and minimal adverse side effects. Lipid nanoparticles (LNPs) have demonstrated a great success for mRNA delivery. Numerous LNPs have been designed and optimized to enhance mRNA stability, facilitate transfection, and ensure intracellular delivery for subsequent processing. Nevertheless, challenges remain to, for example, improve the efficiency of endosomal escape and passive targeting. This review highlights key advancements in the development of mRNA LNPs for cancer immunotherapy. We delve into the design of LNPs for mRNA delivery, encompassing the chemical structures, characterization, and structure-activity relationships (SAR) of LNP compositions. We discuss the key factors influencing the transfection efficiency, passive targeting, and tropism of mRNA-loaded LNPs. We also review the preclinical and clinical applications of mRNA LNPs in cancer immunotherapy. This review can enhance our understanding in the design and application of LNPs for mRNA delivery in cancer immunotherapy.

mRNA-LNP vaccine strategies: Effects of adjuvants on non-parenchymal liver cells and tolerance

The liver, which plays pivotal roles in metabolism and immunity, often confers tolerance, suppressing immune responses to pathogens. Adjuvanted, lipid nanoparticle-encapsulated mRNA vaccines (mRNA-LNPs) offer a promising approach to overcome immune tolerance. In this study, the immunostimulatory activity of well-documented adjuvants, i.e., 2'3'-cyclic guanosine monophosphate-adenosine monophosphate (cGAMP), resiquimod (R848), and polyinosinic:polycytidylic acid (Poly I:C), on non-parenchymal liver cells was determined. When co-applied with mRNA-loaded LNPs, these adjuvants enhanced immune responses at variable extents. Moreover, the efficiency of mRNA translation in the presence of cGAMP was comparable with the non-adjuvanted control. Repetitive co-application of adjuvants with mRNA-LNPs showed improvement in cellular responses when R848 or R848/cGAMP treatments were used. These findings emphasize the need to delineate the delicate balance between immunomodulatory properties and the efficiency of mRNA translation when selecting adjuvants for mRNA-LNP vaccines and offer insights on how to enhance immunity to infectious diseases and cancers that affect the liver.

mRNA vaccine platforms: linking infectious disease prevention and cancer immunotherapy

The advent of mRNA vaccines, accelerated by the global response to the COVID-19 pandemic, marks a transformative shift in vaccine technology. In this article, we discuss the development, current applications, and prospects of mRNA vaccines for both the prevention and treatment of infectious diseases and oncology. By leveraging the capacity to encode antigens within host cells directly, mRNA vaccines provide a versatile and scalable platform suitable for addressing a broad spectrum of pathogens and tumor-specific antigens. We highlight recent advancements in mRNA vaccine design, innovative delivery mechanisms, and ongoing clinical trials, with particular emphasis on their efficacy in combating infectious diseases, such as COVID-19, Zika, and influenza, as well as their emerging potential in cancer immunotherapy. We also address critical challenges, including vaccine stability, optimization of immune responses, and the broader issue of global accessibility. Finally, we review potential strategies for advancing next-generation mRNA vaccines, with the aim of overcoming current limitations in vaccine technology and enhancing both preventive and therapeutic approaches for infectious and oncological diseases.

Visualizing lipid nanoparticle trafficking for mRNA vaccine delivery in non-human primates

mRNA delivered using lipid nanoparticles (LNPs) has become an important subunit vaccine modality, but mechanisms of action for mRNA vaccines remain incompletely understood. Here, we synthesized a metal chelator-lipid conjugate enabling positron emission tomography (PET) tracer labeling of LNP/mRNA vaccines for quantitative visualization of vaccine trafficking in live mice and non-human primates (NHPs). Following intramuscular injection, we observed LNPs distributing through injected muscle tissue, simultaneous with rapid trafficking to draining lymph nodes (dLNs). Deltoid injection of LNPs mimicking human vaccine administration led to stochastic LNP delivery to three different sets of dLNs. LNP uptake in dLNs was confirmed by histology, and cellular analysis of tissues via flow cytometry identified antigen-presenting cells as the primary immune cell type responsible for early LNP uptake and mRNA translation. These results provide insights into the biodistribution of mRNA vaccines administered at clinically relevant doses, injection volumes, and injection sites in an important large animal model for vaccine development.

Impact of Extended Dosing Intervals and Ipsilateral Versus Contralateral Boosting on mRNA Vaccine Immunogenicity in Mice

BACKGROUND

Although mRNA vaccines have the potential to be developed and deployed rapidly to combat infectious diseases, the ideal method of administration and boosting schedule strategy for generating optimal immunogenicity is an area of active research. We compared the immune responses resulting from different schedules for prime-boost and boosting either ipsilaterally or contralaterally in relation to the initial vaccine dose.

METHODS

Influenza hemagglutinin (HA) was used as a model antigen for different vaccination regimens in mice using both mRNA lipid nanoparticles (mRNA-LNP) and AF03-adjuvanted recombinant protein (rHA-AF03) vaccines.

RESULTS

Increasing the prime-boost interval resulted in higher levels of serum anti-HA IgG and functional antibody hemagglutination inhibition (HAI) responses in mRNA-LNP-vaccinated animals, which correlated with an induction of germinal center (GC) B cells and follicular helper T (Tfh) cells in lymph nodes. In addition, longer prime-boost intervals resulted in higher levels of IL-2 and TNF-α producing CD4+ T cells two weeks after boosting. The number of Ig-secreting long-lived plasma cells increased with the length of prime-boost intervals. Contralateral boosting resulted in an increase in HAI titers and GC B cells compared to an ipsilateral boost. However, significantly higher numbers of GC B cells were induced in the draining lymph nodes following ipsilateral boosting than in the non-draining lymph nodes.

CONCLUSIONS

Overall, our data provides insights into the immune mechanisms of action of mRNA-LNP to develop the optimal vaccine regimen for mRNA vaccine platforms.

Pharmaceutical strategies for optimized mRNA expression

Messenger RNA (mRNA)-based immunotherapies and protein in situ production therapies hold great promise for addressing theoretically all the diseases characterized by aberrant protein levels. The safe, stable, and precise delivery of mRNA to target cells via appropriate pharmaceutical strategies is a prerequisite for its optimal efficacy. In this review, we summarize the structural characteristics, mode of action, development prospects, and limitations of existing mRNA delivery systems from a pharmaceutical perspective, with an emphasis on the impacts from formulation adjustments and preparation techniques of non-viral vectors on mRNA stability, target site accumulation and transfection efficiency. In addition, we introduce strategies for synergistical combination of mRNA and small molecules to augment the potency or mitigate the adverse effects of mRNA therapeutics. Lastly, we delve into the challenges impeding the development of mRNA drugs while exploring promising avenues for future advancements.

Current innovations in mRNA vaccines for targeting multidrug-resistant ESKAPE pathogens

The prevalence of multidrug-resistant (MDR) ESKAPE pathogens, including Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa, represents a critical global public health challenge. In response, mRNA vaccines offer an adaptable and scalable platform for immunotherapy against ESKAPE pathogens by encoding specific antigens that stimulate B-cell-driven antibody production and CD8+ T-cell-mediated cytotoxicity, effectively neutralizing these pathogens and combating resistance. This review examines recent advancements and ongoing challenges in the development of mRNA vaccines targeting MDR ESKAPE pathogens. We explore antigen selection, the nuances of mRNA vaccine technology, and the complex interactions between bacterial infections and antibiotic resistance. By assessing the potential efficacy of mRNA vaccines and addressing key barriers to their paraclinical implementation, this review highlights the promising function of mRNA-based immunization in combating MDR ESKAPE pathogens.

Muco-Penetrating Lipid Nanoparticles Having a Liquid Core for Enhanced Intranasal mRNA Delivery

Intranasal delivery of mRNA vaccines offers promising opportunities to combat airborne viruses like SARS-CoV-2 by provoking mucosal immunity, which not only defends against respiratory infection but also prevents contagious transmission. However, the development of nasal mRNA vaccines has been hampered by the lack of effective means to overcome the mucus barrier. Herein, ionizable lipid-incorporated liquid lipid nanoparticles (iLLNs) capable of delivering mRNA cargo across airway mucosa are designed. Adjusting the ratios of ionizable and cationic lipids allows fine-tuning of the pKa of iLLNs to the range of nasal mucosal pH (5.5-6.5), thus facilitating mucus penetration via the formation of near-neutral, PEGylated muco-inert surfaces. When nasally administered to mice, the top candidate iLLN-2/mRNA complexes enable about 60-fold greater reporter gene expression in the nasal cavity, compared to the benchmark mRNA-lipid nanoparticles (ALC-LNP) having the same lipid composition as that of BNT162b2 vaccine. Moreover, a prime-boost intranasal immunization of iLLN-2/mRNA complexes elicits a greater magnitude of SARS-CoV-2 spike-specific mucosal IgA and IgG response than ALC-LNP, without triggering any noticeable inflammatory reactions. Taken together, these results provide useful insights for the design of nasally deliverable mRNA formulations for prophylactic applications.

Improving the Efficacy of Cancer mRNA Vaccines

mRNA vaccines consist of antigen-encoding mRNA, which produces the antigenic protein upon translation. Coupling antigen production with innate immune activation can generate a potent, antigen-specific T-cell response. Clinical reports have demonstrated the ability of mRNA vaccines to elicit an anticancer immune response against various tumor types. Here, we discuss strategies to enhance the potency of mRNA vaccines. We provide an overview of existing knowledge regarding the activation and trafficking mechanisms of mRNA vaccines and share optimization strategies to boost mRNA-mediated antigen production. In addition, we address methods to target mRNA vaccines to dendritic cells and lymph nodes, key initiators of the immune response. Finally, we review strategies for enhancing immune activation using adjuvants compatible with mRNA vaccines. mRNA vaccines offer unique advantages that can be utilized for oncology applications. However, significant work is needed to understand their underlying mechanisms and develop technologies to improve their effectiveness.

Innate Sensing of Viral Nucleic Acids and Their Use in Antiviral Vaccine Development

Viruses pose a significant threat to humans by causing numerous infectious and potentially fatal diseases. Understanding how the host's innate immune system recognizes viruses is essential to understanding pathogenesis and ways to control viral infection. Innate immunity also plays a critical role in shaping adaptive immune responses induced by vaccines. Recently developed adjuvants often include nucleic acids that stimulate pattern recognition receptors which are essential components of innate immunity necessary for activating antigen-presentation cells and thereby bridging innate and adaptive immunity. Therefore, understanding viral nucleic acid sensing by cytosolic sensors is essential, as it provides the potential means for developing new vaccine strategies, including effective adjuvants.

Linking vaccine adjuvant mechanisms of action to function

Vaccines deliver an immunogen in a manner designed to safely provoke an immune response, leading to the generation of memory T and B cells and long-lived antibody-producing plasma cells. Adjuvants play a critical role in vaccines by controlling how the immune system is exposed to the immunogen and providing inflammatory cues that enable productive immune priming. However, mechanisms of action underlying adjuvant function at the molecular, cell, and tissue levels are diverse and often poorly understood. Here, we review the current understanding of mechanisms of action underlying adjuvants used in subunit protein/polysaccharide vaccines and mRNA vaccines, discuss where possible how these mechanisms of action link to downstream effects on the immune response, and identify knowledge gaps that will be important to fill in order to enable the continued development of more effective adjuvants for challenging pathogens such as HIV and emerging threats.

Extracellular vesicles-based vaccines: Emerging immunotherapies against cancer

Cancer vaccines are promising therapeutic approaches to enhance specific T-cell immunity against most solid tumors. By stimulating anti-tumor immunity, clearing minimal residual disease, and minimizing adverse effects, these vaccines target tumor cells and are effective when combined with immune checkpoint blockade or other immunotherapies. However, the development of tumor cell-based vaccines faces quality issues due to poor immunogenicity, tumor heterogeneity, a suppressive tumor immune microenvironment, and ineffective delivery methods. In contrast, extracellular vesicles (EVs), naturally released by cells, are considered the ideal drug carriers and vaccine platforms. EVs offer highly organ-specific targeting, induce broader and more effective immune responses, and demonstrate superior tissue delivery ability. The development of EV vaccines is crucial for advancing cancer immunotherapy. Compared to cell-based vaccines, EV vaccines produced under Good Manufacturing Practices (GMP) offer advantages such as high safety, ease of preservation and transport, and a wide range of sources. This review summarizes the latest research findings on EV vaccine and potential applications in this field. It also highlights novel neoantigens for the development of EV vaccines against cancer.

Emerging Delivery Systems for Enabling Precision Nucleic Acid Therapeutics

Nucleic acid therapeutics represent a highly promising treatment approach in modern medicine, treating diseases at the genetic level. However, these therapeutics face numerous challenges in practical applications, particularly regarding their stability, effectiveness, cellular uptake efficiency, and limitations in delivering them specifically to target tissues. To overcome these obstacles, researchers have developed various innovative delivery systems, including viral vectors, lipid nanoparticles, polymer nanoparticles, inorganic nanoparticles, protein carriers, exosomes, antibody oligonucleotide conjugates, and DNA nanostructure-based delivery systems. These systems enhance the therapeutic efficacy of nucleic acid drugs by improving their stability, targeting specificity, and half-life in vivo. In this review, we systematically discuss different types of nucleic acid drugs, analyze the major barriers encountered in their delivery, and summarize the current research progress in emerging delivery systems. We also highlight the latest advancements in the application of these systems for treating genetic diseases, infectious diseases, cancer, brain diseases, and wound healing. This review aims to provide a comprehensive overview of nucleic acid drug delivery systems' current status and future directions by integrating the latest advancements in nanotechnology, biomaterials science, and gene editing technologies, emphasizing their transformative potential in precision medicine.

Protection efficacy of mRNA-based SARS-CoV-2 variant vaccine in non-human primates

The rapid emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants that evade immunity elicited by vaccination has posed a global challenge to the control of the coronavirus disease 2019 (COVID-19) pandemic. Therefore, developing countermeasures that broadly protect against SARS-CoV-2 and related sarbecoviruses is essential. Herein, we have developed a lipid nanoparticle (LNP)-encapsulated mRNA (mRNA-LNP) encoding the full-length Spike (S) glycoprotein of SARS-CoV-2 (termed RG001), which confers complete protection in a non-human primate model. Intramuscular immunization of two doses of RG001 in Rhesus monkey elicited robust neutralizing antibodies and cellular response against SARS-CoV-2 variants, resulting in significantly protected SARS-CoV-2-infected animals from acute lung lesions and complete inhibition of viral replication in all animals immunized with low or high doses of RG001. More importantly, the third dose of RG001 vaccination elicited effective neutralizing antibodies against current epidemic XBB and JN.1 strains and similar cellular response against SARS-CoV-2 Omicron variants (BA.1, XBB.1.16, and JN.1) were observed in immunized mice. All these results together strongly support the great potential of RG001 in preventing the infection of SARS-CoV-2 variants of concern (VOCs).

Proteomic and serologic assessments of responses to mRNA-1273 and BNT162b2 vaccines in human recipient sera

Introduction

The first vaccines approved against SARS-CoV-2, mRNA-1273 and BNT162b2, utilized mRNA platforms. However, little is known about the proteomic markers and pathways associated with host immune responses to mRNA vaccination. In this proof-of-concept study, sera from male and female vaccine recipients were evaluated for proteomic and immunologic responses 1-month and 6-months following homologous third vaccination.

Methods

An aptamer-based (7,289 marker) proteomic assay coupled with traditional serology was leveraged to generate a comprehensive evaluation of systemic responsiveness in 64 and 68 healthy recipients of mRNA-1273 and BNT162b2 vaccines, respectively.

Results

Sera from female recipients of mRNA-1273 showed upregulated indicators of inflammatory and immunological responses at 1-month post-third vaccination, and sera from female recipients of BNT162b2 demonstrated upregulated negative regulators of RNA sensors at 1-month. Sera from male recipients of mRNA-1273 showed no significant upregulation of pathways at 1-month post-third vaccination, though there were multiple significantly upregulated proteomic markers. Sera from male recipients of BNT162b2 demonstrated upregulated markers of immune response to doublestranded RNA and cell-cycle G(2)/M transition at 1-month. Random Forest analysis of proteomic data from pre-third-dose sera identified 85 markers used to develop a model predictive of robust or weaker IgG responses and antibody levels to SARS-CoV-2 spike protein at 6-months following boost; no specific markers were individually predictive of 6-month IgG response. Thirty markers that contributed most to the model were associated with complement cascade and activation; IL-17, TNFR pro-apoptotic, and PI3K signaling; and cell cycle progression.

Discussion

These results demonstrate the utility of proteomics to evaluate correlates or predictors of serological responses to SARS-CoV-2 vaccination.

Exploring the impact of lipid nanoparticles on protein stability and cellular proteostasis

Lipid nanoparticles (LNPs) have become pivotal in advancing modern medicine, from mRNA-based vaccines to gene editing with CRISPR-Cas9 systems. Though LNPs based therapeutics offer promising drug delivery with satisfactory clinical safety profiles, concerns are raised regarding their potential nanotoxicity. Here, we explore the impacts of LNPs on protein stability in buffer and cellular protein homeostasis (proteostasis) in HepG2 cells. First, we show that LNPs of different polyethylene glycol (PEG) molar ratios to total lipid ratio boost protein aggregation propensity by reducing protein stability in cell lysate and blood plasma. Second, in HepG2 liver cells, these LNPs induce global proteome aggregation, as imaged by a cellular protein aggregation fluorescent dye (AggStain). Such LNPs induced proteome aggregation is accompanied by decrease in cellular micro-environmental polarity as quantified by a solvatochromic protein aggregation sensor (AggRetina). The observed local polarity fluctuations may be caused by the hydrophobic contents of LNPs that promote cellular proteome aggregation. Finally, we exploit RNA sequencing analysis (RNA-Seq) to reveal activation of unfolded protein response (UPR) pathway and other proteostasis genes upon LNPs treatment. Together, these findings highlight that LNPs may induce subtle proteome stress by compromising protein stability and proteostasis even without obvious damage to cell viability.

Development and Evaluation of the Immunogenic Potential of an Unmodified Nucleoside mRNA Vaccine for Herpes Zoster

BACKGROUND/OBJECTIVES

Approved mRNA vaccines commonly use sequences modified with pseudouridine to enhance translation efficiency and mRNA stability. However, this modification can result in ribosomal frameshifts, reduced immunogenicity, and higher production costs. This study aimed to explore the potential of unmodified mRNA sequences for varicella-zoster virus (VZV) and evaluate whether codon optimization could overcome the limitations of pseudouridine modification.

METHODS

We utilized artificial intelligence (AI) to design several unmodified gE mRNA sequences for VZV, considering factors such as codon preference and secondary structure. The optimized mRNA sequences were assessed for protein expression levels in vitro and were subsequently used to develop a vaccine, named Vac07, encapsulated in a lipid nanoparticle (LNP) delivery system. The immunogenicity of Vac07 was evaluated in mice.

RESULTS

Codon-optimized mRNA sequences showed significantly higher protein expression levels in vitro compared to wild-type (WT) sequences. Vaccination with Vac07 demonstrated immunogenicity in mice that was comparable to, or even superior to, the licensed Shingrix vaccine, characterized by a stronger Th1-biased antibody response and a slightly more robust Th1-type cellular response.

CONCLUSIONS

Codon-optimized unmodified mRNA sequences may also represent a viable approach for mRNA vaccine development. These optimized sequences have the potential to lower production costs while possibly enhancing the immunogenicity of mRNA vaccines. Vac07, developed using this method, shows promise as a potentially more efficient and cost-effective mRNA vaccine candidate for VZV.