Adjuvanticity of aluminium hydroxide and calcium phosphate in diphtheria-tetanus vaccines--I

Tailoring inorganic nanoadjuvants towards next-generation vaccines

Vaccines, one of the most effective and powerful public health measures, have saved countless lives over the past century and still have a tremendous global impact. As an indispensable component of modern vaccines, adjuvants play a critical role in strengthening and/or shaping a specific immune response against infectious diseases as well as malignancies. The application of nanotechnology provides the possibility of precisely tailoring the building blocks of nanoadjuvants towards modern vaccines with the desired immune response. The last decade has witnessed great academic progress in inorganic nanomaterials for vaccine adjuvants in terms of nanometer-scale synthesis, structure control, and functionalization design. Inorganic adjuvants generally facilitate the delivery of antigens, allowing them to be released in a sustained manner, enhance immunogenicity, deliver antigens efficiently to specific targets, and induce a specific immune response. In particular, the recent discovery of the intrinsic immunomodulatory function of inorganic nanomaterials further allows us to shape the immune response towards the desired type and increase the efficacy of vaccines. In this article, we comprehensively review state-of-the-art research on the use of inorganic nanomaterials as vaccine adjuvants. Attention is focused on the physicochemical properties of versatile inorganic nanoadjuvants, such as composition, size, morphology, shape, hydrophobicity, and surface charge, to effectively stimulate cellular immunity, considering that the clinically used alum adjuvants can only induce strong humoral immunity. In addition, the efforts made to date to expand the application of inorganic nanoadjuvants in cancer vaccines are summarized. Finally, we discuss the future prospects and our outlook on tailoring inorganic nanoadjuvants towards next-generation vaccines.

Adjuvants for Animal Vaccines

Vaccines are essential tools for the prevention and control of infectious diseases in animals. One of the most important steps in vaccine development is the selection of a suitable adjuvant. The focus of this review is the adjuvants used in vaccines for animals. We will discuss current commercial adjuvants and experimental formulations with attention to mineral salts, emulsions, bacterial-derived components, saponins, and several other immunoactive compounds. In addition, we will also examine the mechanisms of action for different adjuvants, examples of adjuvant combinations in one vaccine formulation, and challenges in the research and development of veterinary vaccine adjuvants.

Safety of subcutaneous immunotherapy with inhalant allergen extracts: a single-center 30-year experience from Turkey

CONTEXT

Although subcutaneous allergen immunotherapy (SCIT) is effective in allergic rhinitis (AR) and asthma, it carries a risk of local and systemic adverse reactions.

OBJECTIVE

The aim of this study was to evaluate the rates and clinical characteristics of local and systemic reactions (LR and SR), and to identify their relation of demographic features, allergen extracts and diagnosis.

MATERIALS AND METHODS

This study analyzed the administration of SCIT from 1983 to 2013; involving 1816 patients affected by allergic asthma and/or AR.

RESULTS

The rates of SR from SCIT were 0.078% per injection and 9% per patient. According to the World Allergy Organization 2010 grading system, 91 grade 1 reactions (44%), 67 grade 2 reactions (32.3%), 33 grade 3 reactions (16%) and 16 grade 4 reactions (7.7%) were seen. There was no fatal outcome from any of the SRs. Risk factors for a SR included: aluminium-adsorbed extract, pollen-containing vaccines, large LR and recurrent (≥2) LRs. The total LR rates were 0.062% per injection and 5.2% per patient; the small LR rates were 0.027% per injection and 2.3% per patient, and the large LR rate were 0.035% per injection and 2.9% per patient. Female gender, depot extracts, calcium phosphate-adsorbed extract and pollen vaccines were identified as risk factors for LR.

CONCLUSION

The analysis of our data over a 30-year period confirmed that SCIT with inhalant allergens conducted strictly according to the standard protocols and when administrated by experienced staff is a safe method of treatment with only a few side-effects.

Particulate inorganic adjuvants: recent developments and future outlook

Objectives

To review the state of the art and assess future potential in the use of inorganic particulates as vaccine adjuvants.

Key findings

An adjuvant is an entity added to a vaccine formulation to ensure that robust immunity to the antigen is inculcated. The inclusion of an adjuvant is typically vital for the efficacy of vaccines using inactivated organisms, subunit and DNA antigens. With increasing research efforts being focused on subunit and DNA antigens because of their improved safety profiles, the development of appropriate adjuvants is becoming ever more crucial. Despite this, very few adjuvants are licensed for use in humans (four by the FDA, five by the European Medicines Agency). The most widely used adjuvant, alum, has been used for nearly 90 years, yet its mechanism of action remains poorly understood. In addition, while alum produces a powerful antibody Th2 response, it does not provoke the cellular immune response required for the elimination of intracellular infections or cancers. New adjuvants are therefore needed, and inorganic systems have attracted much attention in this regard.

Summary

In this review, the inorganic adjuvants currently in use are considered, and the efforts made to date to understand their mechanisms of action are summarised. We then move on to survey the literature on inorganic particulate adjuvants, focusing on the most interesting recent developments in this area and their future potential.

Protein coated microcrystals formulated with model antigens and modified with calcium phosphate exhibit enhanced phagocytosis and immunogenicity

Protein-coated microcrystals (PCMCs) were investigated as potential vaccine formulations for a range of model antigens. Presentation of antigens as PCMCs increased the antigen-specific IgG responses for all antigens tested, compared to soluble antigens. When compared to conventional aluminium-adjuvanted formulations, PCMCs modified with calcium phosphate (CaP) showed enhanced antigen-specific IgG responses and a decreased antigen-specific IgG1:IgG2a ratio, indicating the induction of a more balanced Th1/Th2 response. The rate of antigen release from CaP PCMCs, in vitro, decreased strongly with increasing CaP loading but their immunogenicity in vivo was not significantly different, suggesting the adjuvanticity was not due to a depot effect. Notably, it was found that CaP modification enhanced the phagocytosis of fluorescent antigen-PCMC particles by J774.2 murine monocyte/macrophage cells compared to soluble antigen or soluble PCMCs. Thus, CaP PCMCs may provide an alternative to conventional aluminium-based acellular vaccines to provide a more balanced Th1/Th2 immune response.

Immunomodulation of atherosclerosis: implications for vaccine development

A number of studies have shown activation of the immune system throughout various stages of atherosclerosis. Recent observations have suggested that activation of immune responses may promote atherosclerosis on one hand by inducing and perpetuating arterial inflammation, whereas on the other hand, selective activation of certain immune functions may inhibit atherosclerosis and arterial inflammation. These observations suggest the possibility that selective suppression of proatherogenic immune responses or selective activation of antiatherogenic immune responses may provide new approaches for atherosclerosis prevention and treatment. Several antigens activating immune responses affecting development of atherosclerosis have been identified. These immune responses may be modulated by presenting the antigens together with different types of adjuvants as well as through the route of administration. In this review, we summarize recent experimental studies using immunomodulatory approaches for treatment of atherosclerosis.

Granulome vaccinal avec hyperplasie lymphocytaire : 10 cas

BACKGROUND

Few cases of cutaneous lymphocytic hyperplasia secondary to vaccination have been published, although such lesions are not rare.

PATIENTS AND METHODS

We report a series of 10 cases registered between 1993 and 2003.

RESULTS

Mean age was 25. The clinical aspect was solitary or multiple subcutaneous nodules, located on the arm, developing after a delay of 1 to 18 months after vaccination. Histologic examination showed a lymphocytic infiltration of the subcutaneous fat, with diffuse and/or follicular pattern, without nuclear atypia, the morphological and immunohistochemical analysis of which revealed the benign nature. In all cases, there was fibrosis and granuloma composed of lymphocytes, plasma cells, eosinophils and macrophages with basophilic cytoplasm. Morin stain showed intralesional aluminium in the 6 investigated cases. Evolution was always benign, with no relapse following exeresis.

DISCUSSION

Cutaneous lymphocytic hyperplasia secondary to vaccination has to be suspected in a young patient with subcutaneous nodules appearing at a vaccination site. Evidence of aluminium in the lesions supports the diagnosis and the hypothesis that aluminium in the vaccine excipient might have a role in the onset of such lesions.

Evaluation of diphtheria convalescent patients to serve as donors for the production of anti-diphtheria immunoglobulin preparations

AIMS

The study was conducted to evaluate the possibility of selecting convalescent diphtheria patients to serve in emergency situations as donors for the production of anti-diphtheria immunoglobulin. To select suitable donors, the criterion of an antitoxin titer >/=3.0 IU/ml was used. In addition, the effects of treatment and the effect of immunization with diphtheria toxoid on the level of anti-diphtheria toxin antibodies were evaluated.

SCOPE

Three groups of diphtheria patients were included in the study. The first group (n = 23) consisted of patients who had a basic antibiotic treatment, with or without serotherapy using horse antitoxin and/or human immunoglobulin. The second group (n = 12) comprised patients examined immediately after the onset of disease. The immunological history of this group was not known. The third group (n = 20) included patients with a known immunization history, treated only with antibiotics but having received a booster immunization with diphtheria toxoid. Antitoxin titers were measured using the toxin binding inhibition (ToBI) assay.

CONCLUSIONS

In the first group, 47.8% (11/23) of the patients had a diphtheria antibody titer >/=3.0 IU/ml. For most of them, however, the antibody titers could have resulted from treatment with exogenous antibodies from horse antitoxin or human immunoglobulin (18/23). Only two of the 11 high-titer subjects had received antibiotics only. Among the second group, only two (16.76%) of the patients had an antibody titer of >/=3.0 IU/ml. In the third group 50% (10/20) of the patients showed an antibody titer of >/=3.0 IU/ml prior to vaccination, and therefore could be directly considered as donors. Three weeks after booster vaccination, 70% (14/20) had an antibody titer of >/=3.0 IU/ml and 1 year after booster vaccination, 28.6% (2/7) of the subjects still had titers of >/=3.0 IU/ml. In 40% of these patients, a decrease was observed 3-4 weeks after the booster dose. It was concluded that convalescent diphtheria patients could be considered as donors in an emergency situation, since approximately half of them showed antitoxin titers of >/=3.0 IU/ml.

Enhanced type I immune response to a hepatitis B DNA vaccine by formulation with calcium- or aluminum phosphate

DNA vaccines induce protective humoral and cell-mediated immune responses in several animal models. When compared with conventional vaccines, however, DNA vaccines often induce lower antibody titers. We have now found that formulation of a DNA vaccine encoding hepatitis B surface antigen with calcium- or aluminum phosphate adjuvants can increase antibody titers by 10-100-fold and decrease the immunogenic dose of DNA by 10-fold. Furthermore, boosting an HBs protein-primed response with the adjuvanted DNA vaccine resulted in a dramatic increase in the HBs-specific IgG2a response reflecting a shift towards a TH1 response. The mechanism by which aluminum phosphate exerts its adjuvant effect is not through increased expression of HBsAg in vivo; rather, the adjuvant appears to increase the number and affinity of HBs peptide antigen-specific IFN-gamma and IL-2 secreting T cells.

Local tissue irritating effects and adjuvant activities of calcium phosphate and aluminium hydroxide with different physical properties

Effects of calcium phosphate and aluminium hydroxide adjuvants with different physical properties were examined in guinea pigs for local histopathological reactions, electron-microscopical changes of macrophages and adjuvanticity on total IgG antibody response to subcutaneously administered ovalbumin (OVA) and tetanus toxoid (TT). Calcium phosphate gel (Ca-gel) induced active inflammatory reactions consisting of neutrophils (pseudoeosinophils) and foamy macrophages associated with many multinuclear giant cells for at least 4 weeks. Aluminium hydroxide gel (Al-gel) also elicited granulomatous inflammatory reactions consisting mainly of macrophages with foamy cytoplasm, small lymphocytes and giant cells at the injection sites for up to 8 weeks or longer. Severity of local tissue irritation due to calcium phosphate gel (Ca-gel) was similar to that due to Al-gel except for the duration of the inflammatory reactions. Calcium phosphate suspension (Ca-sus)-induced local reactions completely ceased by the 4th week, while aluminium hydroxide suspension (Al-sus)-induced reactions were seen up to the 8th week. Electron-microscopical observations showed that both Al-gel and Al-sus caused damage of macrophages. The adjuvant activity of Al-gel for OVA or TT was significantly stronger than that of any other adjuvant material, whereas those of Ca-gel and Ca-sus were not seen at a dose of 3 mg calcium phosphate per millilitre. Al-sus-TT at a dose of 3 mg aluminium hydroxide per millilitre induced very low levels of antibody. These results suggest that calcium phosphate adjuvant may not be an useful alternative to Al adjuvant.

Booster vaccination against diphtheria and tetanus in man. Comparison of three different vaccine formulations--III

Adverse reactions and antibody levels were compared following a booster vaccination of 177 Danish military recruits with a plain, an aluminium hydroxide (0.5 mg Al per human dose, HD) and a calcium phosphate (0.25 mg Ca per HD) adsorbed diphtheria-tetanus (D-T) vaccine. The calcium phosphate adsorbed vaccine was given in a HD of 3 Lf of D and T toxoids and proved to be of equal efficacy as the aluminium hydroxide adsorbed vaccine which was injected in a dose containing twice the antigen amount. The calcium phosphate vaccine caused fewer adverse reactions than the one adsorbed to aluminium hydroxide. The plain vaccine (6 Lf per HD of D and T toxoid) had the highest efficacy with a similar low occurrence of adverse reactions as the calcium phosphate adsorbed vaccine. Potency assays in mice were in accordance with these immunogenicity results in man if a two dose immunization schedule was followed, but not if the vaccines were compared after a single immunization as requested by the procedure for potency testing according to current WHO and European Pharmacopoeia requirements. Both of the adsorbed vaccines primed mice for specific IgE antibody formation. This could be detected after a second immunization with either of the adsorbed vaccines or with the plain D-T vaccine. Also in humans, immunization with the plain vaccine boosted specific IgE formation to a detectable level. This may be ascribed to adjuvant priming during the primary vaccination series some 20 years previously.