Vaccine adjuvants: Tailoring innate recognition to send the right message

Longitudinal effects of Johnson & Johnson COVID-19 vaccination on metabolic biomarkers in type 2 diabetes mellitus in Ethiopia

BACKGROUND

The coronavirus disease 2019 (COVID-19) pandemic has disproportionately impacted individuals with type 2 diabetes mellitus (T2DM), increasing their risk of severe illness and mortality. Vaccination has been a crucial intervention in mitigating these risks. However, the metabolic effects of COVID-19 vaccination, particularly the Johnson & Johnson (J&J) vaccine, in diabetic populations remain inadequately explored. This study investigated the longitudinal effects of the J&J vaccine on lipid and eicosanoid biomarkers to assess its metabolic safety and potential cardiovascular benefits.

AIM

To evaluate the long-term impact of the J&J COVID-19 vaccine on lipid and eicosanoid biomarkers in Ethiopian patients with T2DM.

METHODS

This prospective cohort study was conducted at Adama Hospital Medical College (Oromia, Ethiopia) from May 2023 to June 2024. A total of 224 T2DM patients (57 vaccinated, 167 unvaccinated) were monitored for 1 year. Biomarkers including triglycerides (TGs), high-density lipoprotein (HDL), total cholesterol (TC), prostaglandins (PGs), and thromboxanes (TXs) were measured at baseline and at 3 months, 6 months, 9 months, and 1 year post-vaccination. Statistical analyses included Generalized Estimating Equations to assess longitudinal biomarker changes.

RESULTS

TG and PG levels remained stable across all time points. HDL levels showed a temporary decline at 3 months (mean difference [MD] = -4.33; P < 0.001) and 6 months (MD = -2.62; P < 0.001) but recovered by 9 months (MD = 2.09; P = 0.001) and 1 year (MD = 2.38; P < 0.001). TC exhibited a significant decrease at 3 months (MD = -16.44, P = 0.001) before stabilizing. TX levels showed a consistent decline across all follow-ups (e.g., 1 year: MD = -0.08; P = 0.036), suggesting a reduced thrombotic risk. Correlation analysis indicated significant interrelations among biomarkers, emphasizing their roles in metabolic and inflammatory pathways.

CONCLUSION

The J&J COVID-19 vaccine exhibited metabolic safety in patients with T2DM, with transient HDL and TC reductions that later stabilized and a sustained TX decline, suggesting potential cardiovascular benefits. Further studies are needed to explore long-term immunometabolic effects on high-risk populations.

Yeast-Derived Manganese and Zinc Metal-Organic Framework Composite as a Vaccine Adjuvant for Enhanced Humoral and Cellular Immune Responses

To control pandemics, a universal adjuvant platform that can deliver antigens and stimulate the immune system that rapidly elicits humoral and cellular immune responses is needed, especially one that can stimulate the body's immune system to produce protective immunological memory. However, the design, composition, and mechanism of adjuvants have presented considerable challenges. The types of adjuvants currently approved in clinics are rare and are far from meeting the requirements of vaccine development. In this study, we prepared a yeast-derived manganese and zinc metal-organic framework (MOF) composite particle adjuvant by self-assembling Mn-MOF-74 and ZIF-8 on the surface of yeast and named it yeast@Mn-MOF-74@ZIF-8 (yMZ). yMZ was able to promote the maturation and activation of dendritic cells (DCs), enhance the uptake and presentation of antigens by DCs, increase the production of adaptive immune cells with memory, enhance humoral and cellular immune responses, and promote the activation of the germinal center. Additionally, yMZ allowed for effective control of antigen release and exhibited good biosafety in vivo. In this study, yMZ showed good adjuvant effects on subunits and inactivated vaccines, indicating that it is a next-generation adjuvant candidate with potential application prospects.

Monosaccharide-Based Synthetic TLR4 Agonist Enhances Vaccine Efficacy against Pseudomonas aeruginosa Challenge

Vaccine adjuvants are critical to improve the immunogenicity, efficacy, and durability of vaccines; however, their development has lagged behind that of vaccine antigens. Monophosphoryl lipid A (MPLA), a clinically approved adjuvant that stimulates Toll-like receptor 4 (TLR4), faces manufacturing challenges due to its complex and long synthesis. With the aim of simplifying the structure of MPLA while retaining its biological activity, we developed monosaccharide-based molecules FP18 and FP20Rha that activate TLR4 signaling. Both TLR4 agonists induced robust antibody activity against the model antigen, ovalbumin. Here, we report the potential of these TLR4 agonists to enhance the protective efficacy of the well-characterized OprF antigen against P. aeruginosa infection. OprF adjuvanted with FP18 showed reduced bacterial loads in lungs and spleens, relative to antigen alone in an acute P. aeruginosa pneumonia model. FP18-adjuvanted OprF also enhanced the production of anti-OprF antibodies and stimulated IFNγ and TNF in CD4+ T cells, suggesting a Th1-skewed cellular immune response. These adjuvants have promise for accelerating the development of effective vaccines against P. aeruginosa and other infectious diseases.

Diverse priming outcomes under conditions of very rare precursor B cells

Rare naive B cells have special pathogen-recognition features that enable outsized contributions to protective immunity but infrequently participate in immune responses. We investigatee how germline-targeting vaccine delivery and adjuvant selection affect priming of exceptionally rare BG18-like HIV broadly neutralizing antibody-precursor B cells (<1-in-50 million) in non-human primates. Only escalating dose (ED) priming immunization using the saponin adjuvant SMNP elicited detectable BG18-like cells in germinal centers (GCs) compared with other conditions. All groups had strong GC responses, but only ED+SMNP and bolus+SMNP induced BG18-like memory B cells in >50% of animals. One group had vaccine-specific GC responses equivalent to ED+SMNP but scarce BG18-like B cells. Following homologous boosting, BG18-like memory B cells were present in a bolus priming group but with lower somatic hypermutation and affinities than ED+SMNP. This outcome inversely associated with post-prime antibody titers, suggesting antibody feedback significantly influences rare precursor B cell responses. Thus, antigen and inflammatory stimuli extensively impact priming and affinity maturation of rare B cells.

Nano-adjuvant based on lipo-imiquimod self-assembly for enhanced foot-and-mouth disease virus vaccine immune responses via intradermal immunization

Excellent adjuvants and proper immunization routes play pivotal roles in activating a robust immune response. Nano-adjuvants have the advantages of enhancing immunogenicity, targeting delivery, and improving stability to provide a new solution for vaccine delivery. In this work, we designed and synthesized a pro-immunostimulant of liposolubility imiquimod derivative IMQP, which was synthesized by reaction of palmitoyl chloride with parent imiquimod (IMQ). Using an inactivated foot-and-mouth disease virus (FMDV) as antigen, and the as-synthesized IMQP containing long carbon chain as nano-adjuvant, we formulated a self-assembled foot-and-mouth disease nano-vaccine (IMQP@FMDV) by re-precipitation method for intradermal (I.D.) immunity vaccination. Because of its small size (∼131.75 ± 41.70 nm) and fat-soluble, the as-fabricated lipid nanoparticles (LNPs) showed promising potential for efficient delivery of antigens to immune cells. Also, lysosomal escape was confirmed by co-localization dendritic cells (DCs). Our findings demonstrated that IMQP nano-adjuvant greatly promoted the expression and secretion of cytokines and chemokines with a balance Th1/Th2 immune response via the I.D. administration. Meanwhile, due to the slowly releasing of IMQ by the hydrolysis of IMQP, IMQP persistently stimulated antigen-presenting cells (APCs) maturation and promoted antigen presentation, and subsequently induced the activation of the related downstream NF-кB and MAPK pathways of the TLR7 signaling pathway, thereby stimulated a robust both humoral and cellular immune response.

Metal-Phenolic Network Hydrogel Vaccine Platform for Enhanced Humoral Immunity against Lethal Rabies Virus

Rabies, caused by rabies virus (RABV), is a zoonotic disease with a high mortality rate that has attracted global attention with the goal of eradication by 2030. However, rabies can only be prevented by appropriate and multiple vaccinations, which impede widespread vaccination in developing countries due to its high expenditure. Designing single-dose vaccines is a pressing challenge in the prevention of rabies and other infectious diseases. Herein, a metal-phenolic network (MPN)-based hydrogel vaccine (designated as CGMR) was developed to stimulate potent humoral immunity against RABV infection by a single immunization, resulting in 4.3-fold and 1.8-fold enhancements of virus-neutralizing antibody compared with that induced by inactivated RABV and alum adjuvant. The CGMR, cross-linked by phenol-modified chitosan with manganese ion, could prolong residence time by confining the antigen to the network of hydrogel, acting as a "hydrogel antigen depot". It also stimulated the activation of the cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS)-stimulator of interferon gene (STING) pathway, facilitating dendritic cell maturation and antigen presentation. The vaccine formulation recruited immunocytes and activated the germinal center, enhancing and sustaining humoral immune responses against the virulent RABV challenge. Collectively, this injectable manganese-based hydrogel vaccine provides a universal and ideal avenue for rabies and other infectious diseases.

Cancer vaccines: current status and future directions

Cancer continues to be a major global health burden, with high morbidity and mortality. Building on the success of immune checkpoint inhibitors and adoptive cellular therapy, cancer vaccines have garnered significant interest, but their clinical success remains modest. Benefiting from advancements in technology, many meticulously designed cancer vaccines have shown promise, warranting further investigations to reach their full potential. Cancer vaccines hold unique benefits, particularly for patients resistant to other therapies, and they offer the ability to initiate broad and durable T cell responses. In this review, we highlight the antigen selection for cancer vaccines, introduce the immune responses induced by vaccines, and propose strategies to enhance vaccine immunogenicity. Furthermore, we summarize key features and notable clinical advances of various vaccine platforms. Lastly, we delve into the mechanisms of tumor resistance and explore the potential benefits of combining cancer vaccines with standard treatments and other immunomodulatory approaches to improve vaccine efficacy.

Beyond Needles: Immunomodulatory Hydrogel-Guided Vaccine Delivery Systems

Vaccines are critical for combating infectious diseases, saving millions of lives worldwide each year. Effective immunization requires precise vaccine delivery to ensure proper antigen transport and robust immune activation. Traditional vaccine delivery systems, however, face significant challenges, including low immunogenicity and undesirable inflammatory reactions, limiting their efficiency. Encapsulating or binding vaccines within biomaterials has emerged as a promising strategy to overcome these limitations. Among biomaterials, hydrogels have gained considerable attention for their biocompatibility, ability to interact with biological systems, and potential to modulate immune responses. Hydrogels offer a materials science-driven approach for targeted vaccine delivery, addressing the shortcomings of conventional methods while enhancing vaccine efficacy. This review examines the potential of hydrogel-based systems to improve immunogenicity and explores their dual role as immunomodulatory adjuvants. Innovative delivery methods, such as microneedles, patches, and inhalable systems, are discussed as minimally invasive alternatives to traditional administration routes. Additionally, this review addresses critical challenges, including safety, scalability, and regulatory considerations, offering insights into hydrogel-guided strategies for eliciting targeted immune responses and advancing global immunization efforts.

mRNA Vaccines Against COVID-19 as Trailblazers for Other Human Infectious Diseases

mRNA vaccines represent a milestone in the history of vaccinology, because they are safe, very effective, quick and cost-effective to produce, easy to adapt should the antigen vary, and able to induce humoral and cellular immunity.

METHODS

To date, only two COVID-19 mRNA and one RSV vaccines have been approved. However, several mRNA vaccines are currently under development for the prevention of human viral (influenza, human immunodeficiency virus [HIV], Epstein-Barr virus, cytomegalovirus, Zika, respiratory syncytial virus, metapneumovirus/parainfluenza 3, Chikungunya, Nipah, rabies, varicella zoster virus, and herpes simplex virus 1 and 2), bacterial (tuberculosis), and parasitic (malaria) diseases.

RESULTS

RNA viruses, such as severe acute respiratory syndrome coronavirus (SARS-CoV)-2, HIV, and influenza, are characterized by high variability, thus creating the need to rapidly adapt the vaccines to the circulating viral strain, a task that mRNA vaccines can easily accomplish; however, the speed of variability may be higher than the time needed for a vaccine to be adapted. mRNA vaccines, using lipid nanoparticles as the delivery system, may act as adjuvants, thus powerfully stimulating innate as well as adaptive immunity, both humoral, which is rapidly waning, and cell-mediated, which is highly persistent. Safety profiles were satisfactory, considering that only a slight increase in prognostically favorable anaphylactic reactions in young females and myopericarditis in young males has been observed.

CONCLUSIONS

The COVID-19 pandemic determined a shift in the use of RNA: after having been used in medicine as micro-RNAs and tumor vaccines, the new era of anti-infectious mRNA vaccines has begun, which is currently in great development, to either improve already available, but unsatisfactory, vaccines or develop protective vaccines against infectious agents for which no preventative tools have been realized yet.

Next-generation adjuvant systems containing furfurman drives potent adaptive immunity and host defense as a foot-and-mouth disease vaccine adjuvant

Introduction

Many countries use commercial foot-and-mouth disease (FMD) vaccines to prevent FMD pandemics, but these vaccines have disadvantages, such as repeated vaccinations due to the short persistence of antibody (Ab) titers and incomplete host defense despite high Ab titers. To address these shortcomings, we aimed to develop a novel FMD vaccine containing furfurman as an adjuvant.

Method

To demonstrate the efficacy of the test vaccine, adaptive immunity was evaluated by measuring Ab and neutralizing Ab titers and host defense against viral infections in experimental and target animals. In addition, the expression levels of cytokines [interferon (IFN)α, IFNβ, IFNγ, interleukin (IL)-1β, IL-2, and IL-12p40] were evaluated at the early stages of vaccination to confirm the simultaneous induction of cellular and humoral immune responses induced by the test vaccine.

Result

The groups that received vaccine containing furfurman showed a strong early, mid-term, and long-term immune response and host defense against viral infections compared to the control groups. The significant upregulation observed in cytokine levels in the furfurman group compared to those in the control groups strongly suggest that the test vaccine strengthens cellular immune response and effectively induces a humoral immune response.

Conclusion

Our study demonstrated that furfurman, as an FMD vaccine adjuvant, achieves long-lasting immunity and host defense against viral infections by eliciting potent cellular and humoral immune responses. Therefore, our findings contribute to the design of next-generation FMD vaccines and highlight the potential application of furfurman as an adjuvant for other viral diseases.

Structural analysis and adjuvant activity of a polysaccharide from Urtica macrorrhiza

Developing new vaccine adjuvants for clinical use remains a significant challenge. Herein, we reported a polysaccharide (UMRG) from Urtica macrorrhiza. It has a molecular weight of 743.35 kDa and is composed of rhamnose (Rha), glucuronic acid (GlcA), galacturonic acid (GalA), and galactose (Gal) in a molar ratio of 1.94: 1.00: 4.17: 1.79. Structural analysis revealed that UMRG contains a rhamnogalacturonan I backbone with short side chains of β-Galp-(1→4)-β-GlcAp-(1→4)-β-Glap-(1→ linked at the C-4 position of →2,4)-α-Rhap-(1→. In vivo, UMRG significantly increased the production of antigen-specific IgG, IgG1, and IgG2a by 1.91-, 2.09-, and 3.43-fold, respectively, on day 42 post-immunization. It also promoted the proliferation of splenic lymphocytes, increasing the proportion of CD3+ and CD3+CD4+ T lymphocytes from 32.63 ± 1.13 % to 38.13 ± 2.03 % and from 21.05 ± 0.93 % to 24.34 ± 1.21 %, respectively. Further investigation demonstrated that UMRG promoted the phagocytosis of antigens by dendritic cells, improved their maturation, and stimulated the secretion of the cytokines TNF-α, IL-12, and IL-6. Additionally, both in vitro and in vivo experiments demonstrated that UMRG displayed good biosafety. Our results suggested the Urtica macrorrhiza polysaccharide may exhibit the potential to be developed as a highly efficient and low-toxicity immune adjuvant.

Diverse priming outcomes under conditions of very rare precursor B cells

Rare B cells can have special pathogen-recognition features giving them the potential to make outsized contributions to protective immunity. However, rare naive B cells infrequently participate in immune responses. We investigated how germline-targeting vaccine antigen delivery and adjuvant selection affect priming of exceptionally rare BG18-like HIV broadly neutralizing antibody-precursor B cells (~1 in 50 million) in non-human primates. Only escalating dose (ED) priming immunization using the saponin adjuvant SMNP elicited detectable BG18-like cells in germinal centers (GCs). All groups had strong GC responses, but only ED+SMNP and bolus+SMNP induced BG18-like memory B cells in >50% of animals. One group had vaccine-specific GC responses equivalent to ED+SMNP, but BG18-like memory B cells were rarely detected. Following homologous boosting, BG18-like memory B cells were more frequent in a bolus priming group, but had lower somatic hypermutation and affinities. This outcome was inversely associated with post-prime antibody titers, suggesting antibody feedback can significantly influence rare precursor B cell responses.

Mechanoimmune-Driven Backpack Sustains Dendritic Cell Maturation for Synergistic Tumor Radiotherapy

Cell backpacks present significant potential in both therapeutic and diagnostic applications, making it essential to further explore their interactions with host cells. Current evidence indicates that backpacks can induce sustained immune responses. Our original objective was to incorporate a model antigen into the backpacks to promote dendritic cell maturation and facilitate antigen presentation, thereby inducing immune responses. However, we unexpectedly discovered that both antigen-loaded backpacks and empty backpacks demonstrated comparable abilities to induce dendritic cell maturation, resulting in nearly identical potency in T-cell proliferation. Our mechanistic studies suggest that the attachment of backpacks induces mechanical forces on dendritic cells via opening the PIEZO1 mechanical ion channel. This interaction leads to the remodeling of the intracellular cytoskeleton and facilitates the production of type I interferons by dendritic cells. Consequently, the mechano-immune-driven dendritic cell backpacks, when combined with radiotherapy, induce a robust antitumor effect. This research presents an avenue for leveraging mechanotransduction to enhance combination immunotherapeutic strategies, potentially leading to groundbreaking advancements in the field.

Differential polyvalent passive immune protection of egg yolk antibodies (IgY) against live and inactivated Vibrio fluvialis in fish

Egg yolk antibodies (IgY) can be prepared in large quantities and economically, and have potential value as polyvalent passive vaccines (against multiple bacteria) in aquaculture. This study prepared live and inactivated Vibrio fluvialis IgY and immunized Carassius auratus prior to infection with V. fluvialis and Aeromonas hydrophila. The results showed that the two IgY antibodies hold effective passive protective rates against V. fluvialis and A. hydrophila in C. auratus. Further, the serum of C. auratus recognized the two bacteria in vitro, with a decrease in the bacteria content of the kidney. The phagocytic activity of C. auratus plasma was enhanced, with a decrease in the expression of inflammatory and antioxidant factors. Pathological sections showed that the kidney, spleen, and intestinal tissue structures were intact, and apoptosis and DNA damage decreased in kidney cells. Moreover, the immunoprotection conferred by the live V. fluvialis IgY was higher than that of the inactivated IgY. Addition, live V. fluvialis immunity induced IgY antibodies against outer membrane proteins of V. fluvialis were more than inactivated V. fluvialis immunity. Furthermore, heterologous immune bacteria will not cause infection, so V. fluvialis can be used to immunize chickens to obtain a large amount of IgY antibody. These findings suggest that the passive immunization effect of live bacterial IgY antibody on fish is significantly better than that of inactivated bacterial antibody, and the live V. fluvialis IgY hold potential value as polyvalent passive vaccines in aquaculture.