Inflammatory responses following intramuscular and subcutaneous immunization with aluminum-adjuvanted or non-adjuvanted vaccines

Ally, adversary, or arbitrator? The context-dependent role of eosinophils in vaccination for respiratory viruses and subsequent breakthrough infections

Eosinophils are a critical type of immune cell and central players in type 2 immunity. Existing literature suggests that eosinophils also can play a role in host antiviral responses, typically type 1 immune events, against multiple respiratory viruses, both directly through release of antiviral mediators and indirectly through activation of other effector cell types. One way to prime host immune responses toward effective antiviral responses is through vaccination, where typically a type 1-skewed immunity is desirable in the context of intracellular pathogens like respiratory viruses. In the realm of breakthrough respiratory viral infection in vaccinated hosts, an event in which virus can still establish productive infection despite preexisting immunity, eosinophils are most prominently known for their link to vaccine-associated enhanced respiratory disease upon natural respiratory syncytial virus infection. This was observed in a pediatric cohort during the 1960s following vaccination with formalin-inactivated respiratory syncytial virus. More recent research has unveiled additional roles of the eosinophil in respiratory viral infection and breakthrough infection. The specific contribution of eosinophils to the quality of vaccine responses, vaccine efficacy, and antiviral responses to infection in vaccinated hosts remains largely unexplored, especially regarding their potential roles in protection. On the basis of current findings, we will speculate upon the suggested function of eosinophils and consider the many potential ways by which eosinophils may exert protective and pathological effects in breakthrough infections. We will also discuss how to balance vaccine efficacy with eosinophil-related risks, as well as the use of eosinophils and their products as potential biomarkers of vaccine efficacy or adverse events.

Safety assessments of recombinant DTaP vaccines developed in South Korea

Purpose

Pertussis bacteria have many pathogenic and virulent antigens and severe adverse reactions have occurred when using inactivated whole-cell pertussis vaccines. Therefore, inactivated acellular pertussis (aP) vaccines and genetically detoxified recombinant pertussis (rP) vaccines are being developed. The aim of this study was to assess the safety profile of a novel rP vaccine under development in comparison to commercial diphtheria-tetanus-acellular pertussis (DTaP) vaccines.

Materials and Methods

The two positive control DTaP vaccines (two- and tri-components aP vaccines) and two experimental recombinant DTaP (rDTaP) vaccine (two- and tri-components aP vaccines adsorbed to either aluminum hydroxide or purified oat beta-glucan) were used. Temperature histamine sensitization test (HIST), indirect Chinese hamster ovary (CHO) cell cluster assay, mouse-weight-gain (MWG) test, leukocytosis promoting (LP) test, and intramuscular inflammatory cytokine assay of the injection site performed for safety assessments.

Results

HIST results showed absence of residual pertussis toxin (PTx) in both control and experimental DTaP vaccine groups, whereas in groups immunized with tri-components vaccines, the experimental tri-components rDTaP absorbed to alum showed an ultra-small amount of 0.0066 IU/mL. CHO cell clustering was observed from 4 IU/mL in all groups. LP tests showed that neutrophils and lymphocytes were in the normal range in all groups immunized with the two components vaccine. However, in the tri-components control DTaP vaccine group, as well as two- and tri-components rDTaP with beta-glucan group, a higher monocyte count was observed 3 days after vaccination, although less than 2 times the normal range. In the MWG test, both groups showed changes less than 20% in body temperature and body weight before the after the final immunizations. Inflammatory cytokines within the muscle at the injection site on day 3 after intramuscular injection revealed no significant response in all groups.

Conclusion

There were no findings associated with residual PTx, and no significant differences in both local and systemic adverse reactions in the novel rDTaP vaccine compared to existing available DTaP vaccines. The results suggest that the novel rDTaP vaccine is safe.

Safety and immunogenicity of a 15-valent pneumococcal conjugate vaccine in Japanese healthy infants: A Phase I study (V114-028)

This Phase I study evaluated the safety, tolerability, and immunogenicity of V114, a 15-valent pneumococcal conjugate vaccine (PCV), via subcutaneous (SC) or intramuscular (IM) administration, in healthy Japanese infants 3 months of age. A total of 133 participants were randomized to receive four doses (3 + 1 regimen) of V114-SC (n = 44), V114-IM (n = 45), or 13-valent PCV (PCV13)-SC (n = 44) at 3, 4, 5, and 12-15 months of age. Diphtheria, tetanus, and pertussis-inactivated poliovirus (DTaP-IPV) vaccine was administered concomitantly at all vaccination visits. The primary objective was to assess the safety and tolerability of V114-SC and V114-IM. Secondary objectives were to assess the immunogenicity of PCV and DTaP-IPV at 1-month post-dose 3 (PD3). On days 1-14 following each vaccination, the proportions of participants with systemic adverse events (AEs) were comparable across interventions, whereas injection-site AEs were higher with V114-SC (100.0%) and PCV13-SC (100.0%) than with V114-IM (88.9%). Most AEs were mild or moderate in severity and no vaccine-related serious AEs or deaths were reported. Serotype-specific immunoglobulin G (IgG) response rates at 1-month PD3 were comparable across groups for most shared serotypes between V114 and PCV13. For additional V114 serotypes 22F and 33F, IgG response rates were higher with V114-SC and V114-IM than with PCV13-SC. DTaP-IPV antibody response rates at 1-month PD3 for V114-SC and V114-IM were comparable with PCV13-SC. Findings suggest that vaccination with V114-SC or V114-IM in healthy Japanese infants is generally well tolerated and immunogenic.

Addressing practical issues in the smooth implementation of revised guidelines for non-clinical studies of vaccines for infectious disease prevention

Herein, we investigated possible practical issues for the smooth implementation of the revised Japanese Guidelines for Non-clinical Studies of Vaccines for the Prevention of Infectious Diseases, which were raised in response to public comments on the proposed guideline revision and a gap analysis of the World Health Organization and European Medicines Agency guidelines. We identified main issues such as the non-clinical safety studies of adjuvants and evaluation of local cumulative tolerance in toxicity studies. The revised Japanese Pharmaceuticals and Medical Devices Agency (PMDA)/Ministry of Health, Labour and Welfare (MHLW) guidelines require non-clinical safety studies for vaccines containing new adjuvants, but additional safety pharmacology studies or safety studies in two animal species may be required if non-clinical safety studies raise any concerns (i.e., systemic distribution). Adjuvant biodistribution studies may aid in understanding vaccine characteristics. The evaluation of local cumulative tolerance in non-clinical studies, which was the focus of the Japanese review, can be omitted by including a warning in the package insert to avoid injection to the same site. The study's findings will be reflected in a Q&A to be released by the Japanese MHLW. We hope that this study will contribute to the global and harmonized development of vaccines.

Critical evaluation on roles of macrophagic myofasciitis and aluminum adjuvants in HPV vaccine-induced adverse events

Cervical cancer is caused by human papillomavirus (HPV) infection, which is preventable by HPV vaccines. In Japan, the HPV vaccination rate has remained extremely low due to the concerns for alleged neuropsychological symptoms or "diverse symptoms" following injections of two HPV vaccines, Cervarix and Gardasil, in HPV vaccine lawsuits. In the lawsuits, the attorneys' group has used several manuscripts proposing that aluminum (Al) adjuvant contained in HPV vaccines causes an immune-mediated disease, called macrophagic myofasciitis (MMF), as well as pathology in the central nervous system (CNS). We scientifically evaluated these manuscripts describing the "Al adjuvant-induced pathologies," particularly MMF. Although MMF patients have been reported to develop clinical symptoms/signs in various organs, including the CNS, muscle biopsy of the patients and animal experiments demonstrated that MMF pathology was localized only at the injected muscle. No muscle pathology which characterizes MMF was observed in any other muscles; thus, the systemic and neurological signs of MMF cases were irrelevant to localized MMF pathology. We evaluated that MMF-like pathology was induced as a local inflammatory response following vaccinations; MMF pathology was not the cause of systemic inflammation or "diverse symptoms." Lastly, MMF cases have been reported after vaccinations with Al-hydroxide-containing vaccines exclusively. As Al-hydroxide is a component of Cervarix, but not Gardasil, "diverse symptoms" following two HPV vaccinations in Japan cannot be explained by MMF. Our evaluation would help readers understand the validity of the manuscripts on the role of Al adjuvants or MMF for the alleged "diverse symptoms."

Effectiveness and safety of injectable human papilloma virus vaccine administered as eyedrops

Mucosal vaccines have the advantages of ease of administration and the induction of strong mucosal immunity and a systemic immune response. Recently, the eye mucosa has been shown to be an effective and safe alternative vaccination route against influenza, Toxoplasma gondii infection, and hemolytic uremic syndrome in mice. In this study, we showed that the commercially available human papilloma virus (HPV) vaccine, Cervarix, induced significant immune reactions in terms of anti-HPV antigen (Ag)-specific immunoglobulin G (IgG) and IgA antibody production following eyedrop (ED) vaccination in mice. The HPV ED vaccines (EDV) provoked no signs of inflammation within 24 h, as indicated by the inflammatory cytokine mRNA levels and infiltration of mononuclear cells in inoculation sites. Moreover, the morphology of the cornea and retina and intraocular pressure of mice did not change after the HPV EDV. The functions of photoreceptor cells, including rod and cone cells, were normal following the HPV EDV inoculation in mice. These results suggest that Cervarix EDV could be a potent, safe, and effective mucosal vaccine against HPV-associated cancers.

Comparison of cytokine production in mice inoculated with messenger RNA vaccines BNT162b2 and mRNA-1273

Two messenger RNA (mRNA) vaccines of BNT162b2 and mRNA-1273 were licensed. The most common adverse event is regional pain at the injection site in 80%. As systemic reactions, fatigue and headache were noted in 40%-60% and febrile illness in 10%-40% of the recipients. To investigate the mechanism of adverse events, cytokine profiles were investigated in mice. Muscle tissue and serum samples were obtained on days 0, 1, 3, 5, and 7, and at 2 and 4 weeks after the first dose. The second dose was given 4 weeks after the first dose and samples were obtained. After inoculation with 0.1 mL of mRNA-1273, IFN-γ and IL-2 were detected in muscle tissues and serum samples on day 1 of the second doses, and similar profiles were observed for IL-4, IL-5, and IL-12 production. mRNA-1273 induced higher levels of Th1 and Th2 cytokines. TNF-α was induced in muscle tissues on day 1 of the first dose and enhanced on day 1 of the second dose after inoculation with BNT162b2 and mRNA-1273. IL-6 was also detected in muscle tissue on day 1 of the first dose, but it decreased after day 3, and enhanced production was demonstrated on day 1 of the second dose. Granulocyte colony-stimulating factor in muscle tissues showed a similar profile. The induction of inflammatory cytokines in the mouse model is related to the cause of adverse events in humans, with a higher incidence of adverse events after the second dose.

Juvenile Membranous Nephropathy Developed after Human Papillomavirus (HPV) Vaccination

A 16-year-old girl with no history of renal disease had a fever of 38 °C after her second HPV vaccination and was identified as positive for proteinuria. As she maintained urinary protein of 3.10 g/gCr and 5-9 urinary red blood cells/HPF, a renal biopsy was performed and small spikes on PAM staining with the granular deposition of IgG1++ and IgG3+ on the glomerular capillary wall were discovered by immunofluorescence, although PLA2R immunostaining was negative. Analysis by electron microscope showed electron density deposition in the form of fine particles under the epithelium. The diagnosis was secondary membranous nephropathy stage II. Immunostaining with the anti-p16 INK4a antibody was positive for glomerular cells, and Western blot analysis of urinary protein showed a positive band for p16 INK4a. However, laser-microdissection mass spectrometry analysis of a paraffin section of glomeruli failed to detect HPV proteins. It is possible that the patient was already infected with HPV and administration of the HPV vaccine may have caused secondary membranous nephropathy.

Appropriate Needle Length Determined by Ultrasonic Echography for Intramuscular Injection in Japanese Elderly over 50 Years

Adjuvanted vaccines are administered through intramuscular injection. To perform appropriate injection using an appropriate needle in different age groups or different daily living activities, we investigated the depth from the skin surface to muscle fascia and bone in the deltoid muscle area in 156 elderly aged ≥ 50 years by ultrasonic echography. Subjects consisted of 50 healthy elderly aged 50−64 years, 50 subjects aged 65−74 years, and 56 subjects aged ≥ 75 years (20 outpatients, 18 who needed nursing care, and 18 bedridden in a nursing home). The mean depth ± 1.0 SD from the skin surface to muscle fascia was 7.52 ± 2.13 mm for subjects aged ≥ 75 years, being shorter than 9.16 ± 3.02 mm in those aged 50−64years (p < 0.01). The depth from the skin surface to bone was 22.54 ± 3.85 mm for subjects aged ≥ 75 years and 25.41 ± 4.24 mm for those aged 65−74 years, significantly shorter than those aged 50−64 years (p < 0.01), depending on the reduced muscle volume. The subcutaneous volume length was greater in females (8.29 ± 2.63 mm) than in males (5.62 ± 2.80 mm) aged 50−64 years (p < 0.01). A similar result was obtained in those aged 65−74 years, but there was no difference in the muscle volume length. Our study found that a five-eighths of an inch (16 mm) needle was an appropriate length for average-sized elderly aged ≥ 50 years, but it should be longer for those with large body sizes.

Inflammation-related adverse reactions following vaccination potentially indicate a stronger immune response

Concerns about vaccine safety are an important reason for vaccine hesitancy, however, limited information is available on whether common adverse reactions following vaccination affect the immune response. Data from three clinical trials of recombinant vaccines were used in this post hoc analysis to assess the correlation between inflammation-related solicited adverse reactions (ISARs, including local pain, redness, swelling or induration and systematic fever) and immune responses after vaccination. In the phase III trial of the bivalent HPV-16/18 vaccine (Cecolin®), the geometric mean concentrations (GMCs) for IgG anti-HPV-16 and -18 (P<0.001) were significantly higher in participants with any ISAR following vaccination than in those without an ISAR. Local pain, induration, swelling and systemic fever were significantly correlated with higher GMCs for IgG anti-HPV-16 and/or anti-HPV-18, respectively. Furthermore, the analyses of the immunogenicity bridging study of Cecolin® and the phase III trial of a hepatitis E vaccine yielded similar results. Based on these results, we built a scoring model to quantify the inflammation reactions and found that the high score of ISAR indicates the strong vaccine-induced antibody level. In conclusion, this study suggests inflammation-related adverse reactions following vaccination potentially indicate a stronger immune response.

Intrapulmonary vaccination with delta-inulin adjuvant stimulates non-polarised chemotactic signalling and diverse cellular interaction

There is an urgent need for novel vaccination strategies to combat respiratory pathogens. Mucosal vaccine delivery is an attractive option as it directly targets the site of infection; however, preclinical development has been hindered by a lack of suitable mucosal adjuvants and a limited understanding of their immune effects in the lung environment. Herein, we define the early immune events following the intrapulmonary delivery of a vaccine incorporating the adjuvant delta-inulin. Analysis of the early inflammatory response showed vaccine-induced innate cell recruitment to lungs and local lymph nodes (LN) was transient and non-polarised, correlating with an increase in pulmonary chemotactic factors. Use of fluorescently labelled adjuvant revealed widespread tissue dissemination of adjuvant particles, coupled with broad cellular uptake and transit to the lung-draining LN by a range of innate immune cells. Mass cytometric analysis revealed extensive phenotypic changes in innate and adaptive cell subsets induced by vaccination; this included identification of unconventional lymphocytes such as γδ-T cells and MAIT cells that increased following vaccination and displayed an activated phenotype. This study details a comprehensive view of the immune response to intrapulmonary adjuvant administration and provides pre-clinical evidence to support delta-inulin as a suitable adjuvant for pulmonary vaccines.

Intramuscular BoNT/A injections cause an inflammatory response in the muscle tissue of rats

Objectives

The purpose of the present study was to investigate whether intramuscular BoNT/A injections cause an systemic inflammatory response and a local inflammatory response in the muscle tissue.

Methods

Thirty-two male Sprague Dawley rats treated with BoNT/A (i.m., 1IU) were divided in four groups, depending on the time of BoNT/A injection (2 days before, 1, 2, and 4 weeks before the experiment). Bio-Plex Pro Rat Cytokine 23-plex Multiplex Assay (Bio-Rad, USA).

Results

Systemic inflammation: 17 cytokines (IL1-α ( p = 0.005), IL-1β ( p = 0.01), IL-2 ( p = 0.04), IL-4 ( p = 0.03), IL-6 ( p = 0.03), IL-10 ( p = 0.02), IL12(p70) ( p = 0.03), IL-13 ( p = 0.04), IL-17 ( p = 0.03), GM-CSF ( p = 0.03), INF-γ ( p = 0.03), MIP-1α ( p = 0.03), MIP-3α ( p = 0.04), RANTES ( p = 0.001), TNF-α ( p = 0.04), vascular endothelial growth factor ( p = 0.03), and MCP-1 ( p = 0.02)) showed significantly higher expression levels 2 days after intramuscular BoNT/A injections compared to other time points (1, 2, and 4 weeks). Local inflammation: 12 cytokines (IL-1β ( p = 0.02), IL-6 ( p = 0.002), IL-10 ( p = 0.02), IL-13 ( p = 0.04), IL-17 ( p = 0.02), TNF-α ( p = 0.001), GM-CSF ( p = 0.01), M-CSF ( p = 0.04), MIP-1α ( p = 0.04), MIP-3α ( p = 0.002), RANTES ( p = 0.02), and MCP-1( p = 0.004)) showed higher expression levels 2 and/or 4 weeks after intramuscular BoNT/A injections compared to the other time points (2 days and 1 week).

Conclusion

Intramuscular BoNT/A injections result in a rapid systemic inflammatory response that only lasts a couple of days. At the same time, intramuscular BoNT/A injections cause an inflammatory response locally in the muscle with significantly higher cytokine levels 2 and/or 4 weeks after injections.

Comparative safety and efficacy of two bivalent vaccines containing Newcastle disease LaSota and avian influenza H9N2 Sidrap isolate formulated with different oil adjuvants

Background and Aim:

Newcastle disease (ND) and avian influenza (AI) are two devastating diseases of poultry, which cause great economic losses to the poultry industry and disrupt food security in our country. The use of ND-AI inactive bivalent vaccine is very effective and economical to prevent and control ND and AI disease. Bivalent ND LaSota-AI H9N2 vaccine is not yet available in Indonesia. The inactivated vaccines used in poultry industry often require oil adjuvant to elicit a sufficient immune response. This study aimed to develop the bivalent inactive vaccines containing ND LaSota and AI H9N2 Sidrap isolate which are local isolates as poultry vaccine candidates, and formulated with two different commercial adjuvants, then compared.

Materials and Methods:

Two vaccines bivalent were prepared by emulsifying inactivated Newcastle disease virus (LaSota strain) and AI H9N2 Sidrap isolate viruses with Marcol white mineral oil and Montanide ISA70 adjuvants. Both of bivalent vaccines were tested for safety (physical and histopathological at the injection site) and efficacy in specific-pathogen-free chickens. Parameters used for the evaluation of the efficacy were immunogenicity by hemagglutination inhibition and protection percentage.

Results:

Both bivalent vaccines are safe to use. Post-vaccination (PV) immune response was observed using a hemagglutination inhibition test at 2, 3, 4, 5, 6, 7, and 8 weeks of PV. The bivalent vaccine B gives a better immune response to ND at 2, 3, and 4 weeks of PV (p<0.05) compared to the bivalent vaccine A, but in 5, 6, 7, and 8 weeks, the PV does not show differences in the immune response. The immune response to AI H9N2 showed differences at weeks 2 and 3 PV (p<0.05) with the bivalent vaccine B indicated higher immunity. A single immunization with both bivalent vaccines induces 100% protection in chickens that have been vaccinated against the deadly challenge with the virulent ND virus.

Conclusion:

Both of bivalent vaccines are safe to use and provide good efficacy against virulent ND viruses, but bivalent vaccine B (with Montanide ISA70 adjuvant) shows better immune response than bivalent vaccine A (Marcol white mineral oil adjuvant).

Unequivocal imaging of aluminium in human cells and tissues by an improved method using morin

Aluminium is biologically reactive and its ability to potentiate the immune response has driven its inclusion in both veterinary and human vaccines. Consequently, the need for unequivocal visualisation of aluminium in vivo has created a focused research effort to establish fluorescent molecular probes for this purpose. The most commonly used direct fluorescent labels for the detection of aluminium are morin (2',3,4',5,7-pentahydroxyflavone) and lumogallion [4-chloro-3-(2,4-dihydroxyphenylazo)-2-hydroxybenzene-1-sulphonic acid]. While the former has gained popularity in the detection of aluminium in plants and predominantly within root tips, the latter boasts greater sensitivity and selectivity for the detection of aluminium in human cells and tissues. Herein, we have developed a simplified morin staining protocol using the autofluorescence quenching agent, Sudan Black B. This modified protocol improves tissue morphology and increases analytical sensitivity, which allows intracellular aluminium to be detected in monocytes and when co-localised with senile plaques in human brain tissue of donors diagnosed with familial Alzheimer's disease. Overall, our results demonstrate a simple approach to minimise false positives in the use of morin to unequivocally detect aluminium in vivo.

A comparison of the immune responses induced by antigens in three different archaeosome-based vaccine formulations

Archaeosomes are liposomes composed of natural or synthetic archaeal lipids that can be used as adjuvants to induce strong long-lasting humoral and cell-mediated immune responses against entrapped antigen. However, the entrapment efficiency of antigen within archaeosomes constituted using standard liposome forming methodology is often only 5-40%. In this study, we evaluated different formulation methods using a simple semi-synthetic archaeal lipid (SLA, sulfated lactosyl archaeol) and two different antigens, ovalbumin (OVA) and hepatitis B surface antigen (HBsAg). Antigen was entrapped within archaeosomes using the conventional thin film hydration-rehydration method with or without removal of non-entrapped antigen, or pre-formed empty archaeosomes were simply admixed with an antigen solution. Physicochemical characteristics were determined (size distribution, zeta potential, vesicle morphology and lamellarity), as well as location of antigen relative to bilayer using cryogenic transmission electron microscopy (TEM). We demonstrate that antigen (OVA or HBsAg) formulated with SLA lipid adjuvants using all the different methodologies resulted in a strong antigen-specific immune response. Nevertheless, the advantage of using a drug substance process that comprises of simply admixing antigen with pre-formed empty archaeosomes, represents a simple, efficient and antigenic dose-sparing formulation for adjuvanting and delivering vaccine antigens.

Down selecting adjuvanted vaccine formulations: a comparative method for harmonized evaluation

Background

The need for rapid and accurate comparison of panels of adjuvanted vaccine formulations and subsequent rational down selection, presents several challenges for modern vaccine development. Here we describe a method which may enable vaccine and adjuvant developers to compare antigen/adjuvant combinations in a harmonized fashion. Three reference antigens: Plasmodium falciparum apical membrane antigen 1 (AMA1), hepatitis B virus surface antigen (HBsAg), and Mycobacterium tuberculosis antigen 85A (Ag85A), were selected as model antigens and were each formulated with three adjuvants: aluminium oxyhydroxide, squalene-in-water emulsion, and a liposome formulation mixed with the purified saponin fraction QS21.

Results

The nine antigen/adjuvant formulations were assessed for stability and immunogenicity in mice in order to provide benchmarks against which other formulations could be compared, in order to assist subsequent down selection of adjuvanted vaccines. Furthermore, mouse cellular immune responses were analyzed by measuring IFN-γ and IL-5 production in splenocytes by ELISPOT, and humoral responses were determined by antigen-specific ELISA, where levels of total IgG, IgG1, IgG2b and IgG2c in serum samples were determined.

Conclusions

The reference antigens and adjuvants described in this study, which span a spectrum of immune responses, are of potential use as tools to act as points of reference in vaccine development studies. The harmonized methodology described herein may be used as a tool for adjuvant/antigen comparison studies.

Safety and biodistribution of sulfated archaeal glycolipid archaeosomes as vaccine adjuvants

Archaeosomes are liposomes comprised of ether lipids derived from various archaea. Unlike conventional ester-linked liposomes, archaeosomes exhibit high pH and thermal stability. As adjuvants, archaeosomes can induce robust, long-lasting humoral and cell-mediated immune responses and enhance protection in murine models of infectious disease and cancer. Archaeosomes constituted with total polar lipids (TPL) of various archaea are relatively complex, comprising >10 different lipid compounds. Archaeosomes can be constituted with semi-synthetic glycerolipids built on ether-linked isoprenoid phytanyl cores with varied synthetic glycol- and amino-head groups. However, such semi-synthetic archaeosomes involve many synthetic steps to arrive at the final desired glycolipid composition. We have developed a novel archaeosome formulation comprising a sulfated saccharide group covalently linked to the free sn-1 hydroxyl backbone of an archaeal core lipid (sulfated S-lactosylarchaeol, SLA) mixed with uncharged glycolipid (lactosylarchaeol, LA). This new class of adjuvants can be easily synthesized and retains strong immunostimulatory activity for induction of cell-mediated immunity following systemic immunization. Herein, we demonstrate the safety of SLA/LA archaeosomes following intramuscular injection to mice and evaluate the immunogenicity, in vivo distribution and cellular uptake of antigen (ovalbumin) encapsulated into SLA/LA archaeosomes. Overall, we have found that semi-synthetic sulfated glycolipid archaeosomes are a safe and effective novel class of adjuvants capable of inducing strong antigen-specific immune responses in mice and protection against subsequent B16 melanoma tumor challenge. A key step in their mechanism of action appears to be the recruitment of immune cells to the injection site and the subsequent trafficking of antigen to local draining lymph nodes.

Investigating toxicity specific to adjuvanted vaccines

In an attempt to understand the unique toxicity of adjuvanted vaccines, we studied how toxicity develops over time following vaccine administration. In addition to on- and off-target toxicity typically observed with general pharmaceuticals, we observed toxicity associated with both the generation and the broad action of effectors (antibodies and/or cytotoxic T lymphocytes, CTLs). The impact on effector generation appears to be related to local tolerance specific to the adjuvant. The vaccine immune response by effectors serves to demonstrate species relevance as outlined in the recent WHO guideline on the nonclinical evaluation of adjuvanted vaccines. When regarded as pharmaceuticals that function at sites of local administration, adjuvants have inherent on- and off-target toxicity. On-target toxicity of the adjuvant is typically associated with effector generation, and could vary depending on animal species. Therefore, the use of species with sensitivity to adjuvants described in the WHO guidelines is required to evaluate the toxicity of the vaccine associated with effector generation. Changes in safety pharmacology endpoints would be considered off-target and further studies are conducted only if changes in these endpoints are observed in nonclinical or clinical studies. Thus our decision tree does not recommend the routine conduct of stand-alone safety pharmacology studies.

Somatoform and neurocognitive syndromes after HPV immunization are not associated to cell-mediated hypersensitivity to aluminum

Vaccines against human papilloma virus (HPV) have been demonstrated to be very effective to prevent infection-related neoplasms. However, several reports describing heterogeneous post-vaccination phenomena have been published in last few years. The spectrum of these disorders includes both immune-mediated neurological diseases and neuropsychiatric functional disorders. Some researchers speculated about a genetic predisposition, but others hypothesized a role of adjuvants, including some metals and, particularly, aluminum. Here, we tested sixteen young girls developing somatoform and neurocognitive syndromes after the HPV immunization, through MELISA® test, detecting cell-mediated hypersensitivity to several metals. We found no association between these neurocognitive disorders and the results provided by this test; importantly, no patients showed hypersensitivity to aluminum, which is the inorganic adjuvant included in HPV vaccines. Thus, if aluminum played a role in the pathophysiology of musculoskeletal and neurocognitive disturbances occurring in some young girls after HPV immunization, that should recognize other mechanisms than the activation of aluminum-specific lymphocytes.

Progress toward the Development of a NEAT Protein Vaccine for Anthrax Disease

Bacillus anthracis is a sporulating Gram-positive bacterium that is the causative agent of anthrax and a potential weapon of bioterrorism. The U.S.-licensed anthrax vaccine is made from an incompletely characterized culture supernatant of a nonencapsulated, toxigenic strain (anthrax vaccine absorbed [AVA]) whose primary protective component is thought to be protective antigen (PA). AVA is effective in protecting animals and elicits toxin-neutralizing antibodies in humans, but enthusiasm is dampened by its undefined composition, multishot regimen, recommended boosters, and potential for adverse reactions. Improving next-generation anthrax vaccines is important to safeguard citizens and the military. Here, we report that vaccination with recombinant forms of a conserved domain (near-iron transporter [NEAT]), common in Gram-positive pathogens, elicits protection in a murine model of B. anthracis infection. Protection was observed with both Freund's and alum adjuvants, given subcutaneously and intramuscularly, respectively, with a mixed composite of NEATs. Protection correlated with an antibody response against the NEAT domains and a decrease in the numbers of bacteria in major organs. Anti-NEAT antibodies promote opsonophagocytosis of bacilli by alveolar macrophages. To guide the development of inactive and safe NEAT antigens, we also report the crystal structure of one of the NEAT domains (Hal) and identify critical residues mediating its heme-binding and acquisition activity. These results indicate that we should consider NEAT proteins in the development of an improved antianthrax vaccine.

Enhancement of humoral immunity by the type II heat-labile enterotoxin LT-IIb is dependent upon IL-6 and neutrophils

LT-IIb, a type II heat-labile enterotoxin produced by Escherichia coli, is a potent intradermal adjuvant that enhances immune responses to coadministered antigens. Although the immune mechanisms that promote this augmented immune response have not been well defined, prior intradermal immunization experiments suggested that early cellular and immunomodulatory events at the site of immunization modulated the augmentation of antigen-specific immune responses by LT-IIb. To investigate that hypothesis, mice were intradermally immunized with a recombinant ricin vaccine, a prospective toxin subunit antigen, in the presence and absence of LT-IIb. Analysis of tissue-fluid collection, coupled with histologic sections from the site of intradermal immunization, revealed that a single dose of LT-IIb induced local production of interleukin 6 and promoted a regional infiltration of neutrophils. The adjuvant effects of LT-IIb were abrogated in interleukin 6-deficient mice and when mice were depleted of neutrophils by pretreatment with anti-Ly6G. Overall, these data firmly demonstrated that LT-IIb, when used as an intradermal adjuvant, recruits neutrophils and is a potent rapid inducer of interleukin 6.

Oral administration of recombinant Neisseria meningitidis PorA genetically fused to H. pylori HpaA antigen increases antibody levels in mouse serum, suggesting that PorA behaves as a putative adjuvant

The Neisseria meningitidis outer membrane protein PorA from a Chilean strain was purified as a recombinant protein. PorA mixed with AbISCO induced bactericidal antibodies against N. meningitidis in mice. When PorA was fused to the Helicobacter pylori HpaA antigen gene, the specific response against H. pylori protein increased. Splenocytes from PorA-immunized mice were stimulated with PorA, and an increase in the secretion of IL-4 was observed compared with that of IFN-γ. Moreover, in an immunoglobulin sub-typing analysis, a substantially higher IgG₁ level was found compared with IgG_2a levels, suggesting a Th2-type immune response. This study revealed a peculiar behavior of the purified recombinant PorA protein per se in the absence of AbISCO as an adjuvant. Therefore, the resistance of PorA to proteolytic enzymes, such as those in the gastrointestinal tract, was analyzed, because this is an important feature for an oral protein adjuvant. Finally, we found that PorA fused to the H. pylori HpaA antigen, when expressed in Lactococcus lactis and administered orally, could enhance the antibody response against the HpaA antigen approximately 3 fold. These observations strongly suggest that PorA behaves as an effective oral adjuvant.

Fluorescent nanodiamonds as a relevant tag for the assessment of alum adjuvant particle biodisposition

BACKGROUND

Aluminum oxyhydroxide (alum) is a crystalline compound widely used as an immunologic adjuvant of vaccines. Concerns linked to alum particles have emerged following recognition of their causative role in the so-called macrophagic myofasciitis (MMF) lesion in patients with myalgic encephalomyelitis, revealing an unexpectedly long-lasting biopersistence of alum within immune cells and a fundamental misconception of its biodisposition. Evidence that aluminum-coated particles phagocytozed in the injected muscle and its draining lymph nodes can disseminate within phagocytes throughout the body and slowly accumulate in the brain further suggested that alum safety should be evaluated in the long term. However, lack of specific staining makes difficult the assessment of low quantities of bona fide alum adjuvant particles in tissues.

METHODS

We explored the feasibility of using fluorescent functionalized nanodiamonds (mfNDs) as a permanent label of alum (Alhydrogel(®)). mfNDs have a specific and perfectly photostable fluorescence based on the presence within the diamond lattice of nitrogen-vacancy centers (NV centers). As the NV center does not bleach, it allows the microspectrometric detection of mfNDs at very low levels and in the long-term. We thus developed fluorescent nanodiamonds functionalized by hyperbranched polyglycerol (mfNDs) allowing good coupling and stability of alum:mfNDs (AluDia) complexes. Specificities of AluDia complexes were comparable to the whole reference vaccine (anti-hepatitis B vaccine) in terms of particle size and zeta potential.

RESULTS

In vivo, AluDia injection was followed by prompt phagocytosis and AluDia particles remained easily detectable by the specific signal of the fND particles in the injected muscle, draining lymph nodes, spleen, liver and brain. In vitro, mfNDs had low toxicity on THP-1 cells and AluDia showed cell toxicity similar to alum alone. Expectedly, AluDia elicited autophagy, and allowed highly specific detection of small amounts of alum in autophagosomes.

CONCLUSIONS

The fluorescent nanodiamond technology is able to overcome the limitations of previously used organic fluorophores, thus appearing as a choice methodology for studying distribution, persistence and long-term neurotoxicity of alum adjuvants and beyond of other types of nanoparticles.

Unequivocal identification of intracellular aluminium adjuvant in a monocytic THP-1 cell line

Aluminium-based adjuvants (ABA) are the predominant adjuvants used in human vaccinations. While a consensus is yet to be reached on the aetiology of the biological activities of ABA several studies have identified shape, crystallinity and size as critical factors affecting their adjuvanticity. In spite of recent advances, the fate of ABA following their administration remains unclear. Few if any studies have demonstrated the unequivocal presence of intracellular ABA. Herein we demonstrate for the first time the unequivocal identification of ABA within a monocytic T helper 1 (THP-1) cell line, using lumogallion as a fluorescent molecular probe for aluminium. Use of these new methods revealed that particulate ABA was only found in the cell cytoplasm. Transmission electron microscopy revealed that ABA were contained within vesicle-like structures of approximately 0.5-1 μm in diameter.