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Human Vaccines & Immunotherapeutics 2015In the past few decades, hundreds of materials have been tried as adjuvant; however, only aluminum-based adjuvants continue to be used widely in the world. Aluminum... (Review)
Review
In the past few decades, hundreds of materials have been tried as adjuvant; however, only aluminum-based adjuvants continue to be used widely in the world. Aluminum hydroxide, aluminum phosphate and alum constitute the main forms of aluminum used as adjuvants. Among these, aluminum hydroxide is the most commonly used chemical as adjuvant. In spite of its wide spread use, surprisingly, the mechanism of how aluminum hydroxide-based adjuvants exert their beneficial effects is still not fully understood. Current explanations for the mode of action of aluminum hydroxide-based adjuvants include, among others, the repository effect, pro-phagocytic effect, and activation of the pro-inflammatory NLRP3 pathway. These collectively galvanize innate as well as acquired immune responses and activate the complement system. Factors that have a profound influence on responses evoked by aluminum hydroxide-based adjuvant applications include adsorption rate, strength of the adsorption, size and uniformity of aluminum hydroxide particles, dosage of adjuvant, and the nature of antigens. Although vaccines containing aluminum hydroxide-based adjuvants are beneficial, sometimes they cause adverse reactions. Further, these vaccines cannot be stored frozen. Until recently, aluminum hydroxide-based adjuvants were known to preferentially prime Th2-type immune responses. However, results of more recent studies show that depending on the vaccination route, aluminum hydroxide-based adjuvants can enhance both Th1 as well as Th2 cellular responses. Advances in systems biology have opened up new avenues for studying mechanisms of aluminum hydroxide-based adjuvants. These will assist in scaling new frontiers in aluminum hydroxide-based adjuvant research that include improvement of formulations, use of nanoparticles of aluminum hydroxide and development of composite adjuvants.
Topics: Adaptive Immunity; Adjuvants, Immunologic; Aluminum Hydroxide; Biomedical Research; Humans; Immunity, Innate; Vaccines
PubMed: 25692535
DOI: 10.1080/21645515.2014.1004026 -
Critical Reviews in Toxicology Oct 2014Abstract Aluminum (Al) is a ubiquitous substance encountered both naturally (as the third most abundant element) and intentionally (used in water, foods,... (Review)
Review
Systematic review of potential health risks posed by pharmaceutical, occupational and consumer exposures to metallic and nanoscale aluminum, aluminum oxides, aluminum hydroxide and its soluble salts.
Abstract Aluminum (Al) is a ubiquitous substance encountered both naturally (as the third most abundant element) and intentionally (used in water, foods, pharmaceuticals, and vaccines); it is also present in ambient and occupational airborne particulates. Existing data underscore the importance of Al physical and chemical forms in relation to its uptake, accumulation, and systemic bioavailability. The present review represents a systematic examination of the peer-reviewed literature on the adverse health effects of Al materials published since a previous critical evaluation compiled by Krewski et al. (2007) . Challenges encountered in carrying out the present review reflected the experimental use of different physical and chemical Al forms, different routes of administration, and different target organs in relation to the magnitude, frequency, and duration of exposure. Wide variations in diet can result in Al intakes that are often higher than the World Health Organization provisional tolerable weekly intake (PTWI), which is based on studies with Al citrate. Comparing daily dietary Al exposures on the basis of "total Al"assumes that gastrointestinal bioavailability for all dietary Al forms is equivalent to that for Al citrate, an approach that requires validation. Current occupational exposure limits (OELs) for identical Al substances vary as much as 15-fold. The toxicity of different Al forms depends in large measure on their physical behavior and relative solubility in water. The toxicity of soluble Al forms depends upon the delivered dose of Al(+3) to target tissues. Trivalent Al reacts with water to produce bidentate superoxide coordination spheres [Al(O2)(H2O4)(+2) and Al(H2O)6 (+3)] that after complexation with O2(•-), generate Al superoxides [Al(O2(•))](H2O5)](+2). Semireduced AlO2(•) radicals deplete mitochondrial Fe and promote generation of H2O2, O2 (•-) and OH(•). Thus, it is the Al(+3)-induced formation of oxygen radicals that accounts for the oxidative damage that leads to intrinsic apoptosis. In contrast, the toxicity of the insoluble Al oxides depends primarily on their behavior as particulates. Aluminum has been held responsible for human morbidity and mortality, but there is no consistent and convincing evidence to associate the Al found in food and drinking water at the doses and chemical forms presently consumed by people living in North America and Western Europe with increased risk for Alzheimer's disease (AD). Neither is there clear evidence to show use of Al-containing underarm antiperspirants or cosmetics increases the risk of AD or breast cancer. Metallic Al, its oxides, and common Al salts have not been shown to be either genotoxic or carcinogenic. Aluminum exposures during neonatal and pediatric parenteral nutrition (PN) can impair bone mineralization and delay neurological development. Adverse effects to vaccines with Al adjuvants have occurred; however, recent controlled trials found that the immunologic response to certain vaccines with Al adjuvants was no greater, and in some cases less than, that after identical vaccination without Al adjuvants. The scientific literature on the adverse health effects of Al is extensive. Health risk assessments for Al must take into account individual co-factors (e.g., age, renal function, diet, gastric pH). Conclusions from the current review point to the need for refinement of the PTWI, reduction of Al contamination in PN solutions, justification for routine addition of Al to vaccines, and harmonization of OELs for Al substances.
Topics: Aluminum; Aluminum Hydroxide; Aluminum Oxide; Animals; Carcinogenesis; Cardiovascular System; Central Nervous System; Disease Models, Animal; Dose-Response Relationship, Drug; Endocrine System; Europe; Gastrointestinal Tract; Guidelines as Topic; Humans; Kidney; Liver; Nanoparticles; Occupational Exposure; Randomized Controlled Trials as Topic; Respiratory System; Risk Assessment; Risk Factors
PubMed: 25233067
DOI: 10.3109/10408444.2014.934439 -
Journal of Toxicology and Environmental... 2007
Review
Topics: Aluminum; Aluminum Compounds; Aluminum Hydroxide; Aluminum Oxide; Animals; Environmental Exposure; Humans; Occupational Exposure; Risk Assessment; Tissue Distribution; Toxicity Tests
PubMed: 18085482
DOI: 10.1080/10937400701597766 -
Ecotoxicology and Environmental Safety May 2023Aluminum (Al) has been classified as a cumulative environmental pollutant that endangers human health. There is increasing evidence to suggest the toxic effects of Al,...
Aluminum (Al) has been classified as a cumulative environmental pollutant that endangers human health. There is increasing evidence to suggest the toxic effects of Al, but the specific action on human brain development remains unclear. Al hydroxide (Al(OH)), the most common vaccine adjuvant, is the major source of Al and poses risks to the environment and early childhood neurodevelopment. In this study, we explored the neurotoxic effect of 5 μg/ml or 25 μg/ml Al(OH) for six days on neurogenesis by utilizing human cerebral organoids from human embryonic stem cells (hESCs). We found that early Al(OH) exposure in organoids caused a reduction in the size, deficits in basal neural progenitor cell (NPC) proliferation, and premature neuron differentiation in a time and dose-dependent manner. Transcriptomes analysis revealed a markedly altered Hippo-YAP1 signaling pathway in Al(OH) exposed cerebral organoid, uncovering a novel mechanism for Al(OH)-induced detrimental to neurogenesis during human cortical development. We further identified that Al(OH) exposure at day 90 mainly decreased the production of outer radial glia-like cells(oRGs) but promoted NPC toward astrocyte differentiation. Taken together, we established a tractable experimental model to facilitate a better understanding of the impact and mechanism of Al(OH) exposure on human brain development.
Topics: Child, Preschool; Humans; Human Embryonic Stem Cells; Aluminum Hydroxide; Neurogenesis; Neural Stem Cells; Organoids
PubMed: 37011512
DOI: 10.1016/j.ecoenv.2023.114863 -
Molecular Microbiology May 2022Aluminum salts have been successfully utilized as adjuvants to enhance the immunogenicity of vaccine antigens since the 1930s. However, the cellular mechanisms behind...
Aluminum salts have been successfully utilized as adjuvants to enhance the immunogenicity of vaccine antigens since the 1930s. However, the cellular mechanisms behind the immune adjuvanticity effect of these materials in antigen-presenting cells are poorly understood. In this study, we investigated the uptake and trafficking of aluminum oxy-hydroxide (AlOOH), in RAW 264.7 murine and U-937 human macrophages-like cells. Furthermore, we determined the impact that the adsorption to AlOOH particulates has on the trafficking of a Bordetella pertussis vaccine candidate, the genetically detoxified pertussis toxin (gdPT). Our results indicate that macrophages internalize AlOOH by constitutive macropinocytosis assisted by the filopodial protrusions that capture the adjuvant particles. Moreover, we show that AlOOH has the capacity to nonspecifically adsorb IgG, engaging opsonic phagocytosis, which is a feature that may allow for more effective capture and uptake of adjuvant particles by antigen-presenting cells (APCs) at the site of vaccine administration. We found that AlOOH traffics to endolysosomal compartments that hold degradative properties. Importantly, while we show that gdPT escapes degradative endolysosomes and traffics toward the retrograde pathway, as reported for the wild-type pertussis toxin, the adsorption to AlOOH diverts gdPT to traffic to the adjuvant's lysosome-type compartments, which may be key for MHC-II-driven antigen presentation and activation of CD4 T cell. Thus, our findings establish a direct link between antigen adsorption to AlOOH and the intracellular trafficking of antigens within antigen-presenting cells and bring to light a new potential mechanism for aluminum adjuvancy. Moreover, the in-vitro single-cell approach described herein provides a general framework and tools for understanding critical attributes of other vaccine formulations.
Topics: Adjuvants, Immunologic; Aluminum; Aluminum Hydroxide; Animals; Humans; Lysosomes; Macrophages; Mice; Pertussis Toxin; Pertussis Vaccine
PubMed: 35344242
DOI: 10.1111/mmi.14900 -
Human Vaccines & Immunotherapeutics Oct 2012Allergen-specific immunotherapy is currently performed via either the subcutaneous or sublingual routes as a treatment for type I (IgE dependent) allergies. Aluminum... (Review)
Review
Allergen-specific immunotherapy is currently performed via either the subcutaneous or sublingual routes as a treatment for type I (IgE dependent) allergies. Aluminum hydroxide or calcium phosphate are broadly used as adjuvants for subcutaneous allergy vaccines, whereas commercial sublingual vaccines rely upon high doses of aqueous allergen extracts in the absence of any immunopotentiator. Adjuvants to be included in the future in products for allergen specific immunotherapy should ideally enhance Th1 and CD4+ regulatory T cell responses. Imunomodulators impacting dendritic or T cell functions to induce IL10, IL12 and IFNγ production are being investigated in preclinical allergy models. Such candidate adjuvants encompass synthetic or biological immunopotentiators such as glucocorticoids, 1,25-dihydroxy vitamin D3, selected probiotic strains (e.g., Lactobacillus and Bifidobacterium species) as well as TLR2 (Pam3CSK4), TLR4 (monophosphoryl lipid A, synthetic lipid A analogs) or TLR9 (CpGs) ligands. Furthermore, the use of vector systems such as mucoadhesive particules, virus-like particles or liposomes are being considered to enhance allergen uptake by tolerogenic antigen presenting cells present in mucosal tissues.
Topics: Adjuvants, Immunologic; Administration, Sublingual; Aluminum Hydroxide; Calcium Phosphates; Desensitization, Immunologic; Humans; Hypersensitivity; Vaccines
PubMed: 23095872
DOI: 10.4161/hv.21688 -
Journal of Immunology Research 2019Adjuvants are a diverse family of substances whose main objective is to increase the strength, quality, and duration of the immune response caused by vaccines. The most... (Review)
Review
Adjuvants are a diverse family of substances whose main objective is to increase the strength, quality, and duration of the immune response caused by vaccines. The most commonly used adjuvants are aluminum-based, oil-water emulsion, and bacterial-origin adjuvants. In this paper, we will discuss how the election of adjuvants is important for the adjuvant-mediated induction of immunity for different types of vaccines. Aluminum-based adjuvants are the most commonly used, the safest, and have the best efficacy, due to the triggering of a strong humoral response, albeit generating a weak induction of cell-mediated immune response. Freund's adjuvant is the most widely used oil-water emulsion adjuvant in animal trials; it stimulates inflammation and causes aggregation and precipitation of soluble protein antigens that facilitate the uptake by antigen-presenting cells (APCs). Adjuvants of bacterial origin, such as flagellin, membranes, and monophosphoryl lipid A (MLA), are known to potentiate immune responses, but their safety and risks are the main concern of their clinical use. This minireview summarizes the mechanisms that classic and novel adjuvants produce to stimulate immune responses.
Topics: Adjuvants, Immunologic; Aluminum Hydroxide; Animals; Antigens, Bacterial; Emulsions; Escherichia coli; Humans; Immunity, Cellular; Lipid A; Oils
PubMed: 31205956
DOI: 10.1155/2019/3974127 -
BioMed Research International 2023The present study is aimed at investigating the long-term effects of the aluminum hydroxide administration in the small intestine, lung, liver, and kidney of male BALB/c...
The present study is aimed at investigating the long-term effects of the aluminum hydroxide administration in the small intestine, lung, liver, and kidney of male BALB/c mice. The mice received via orogastric gavage phosphate buffered or 10 mg/kg aluminum hydroxide 3 times a week for 6 months. Administration of aluminum hydroxide decreased hemoglobin, hematocrit, and erythrocyte. In the blood, kidney and liver function markers were evaluated, and long-term administration of aluminum hydroxide led to an increase in AST levels and a decrease in urea levels. The animals exposed to aluminum showed higher lipid and protein oxidation in all the organs analyzed. In relation to the enzymes involved in antioxidant defense, the lungs showed lower superoxide dismutase (SOD) and catalase activity and a lower reduced and oxidized glutathione (GSH/GSSG) ratio. In the liver, aluminum administration led to a decrease in catalase activity and the GSH/GSSG ratio. Lower catalase activity was observed in the small intestine, as well as in the lungs and liver. In addition to alterations in antioxidant defense, increased levels of the chemokine CCL-2 were observed in the lungs, lower levels of IL-10 in the liver and small intestine, and decreased levels of IL-6 in the intestine of the animals that received aluminum hydroxide for 6 months. Long-term exposure to aluminum promoted steatosis in the liver. In the kidneys, mice treated with aluminum presented a decreased glomerular density than in the naive control group. In the small intestine, exposure caused villi shortening. Our results indicate that long-term oral administration of aluminum hydroxide provokes systemic histological damage, inflammation, and redox imbalance.
Topics: Mice; Male; Animals; Antioxidants; Glutathione Disulfide; Glutathione; Catalase; Aluminum Hydroxide; Mice, Inbred BALB C; Aluminum; Oxidation-Reduction; Superoxide Dismutase; Liver; Inflammation; Oxidative Stress
PubMed: 37854793
DOI: 10.1155/2023/4499407 -
International Journal of Nanomedicine 2020Aluminum salts, although they have been used as adjuvants in many vaccine formulations since 1926, exclusively induce a Th2-biased immune response, thereby limiting...
Crystalline and Amorphous Preparation of Aluminum Hydroxide Nanoparticles Enhances Protective Antigen Domain 4 Specific Immunogenicity and Provides Protection Against Anthrax.
INTRODUCTION
Aluminum salts, although they have been used as adjuvants in many vaccine formulations since 1926, exclusively induce a Th2-biased immune response, thereby limiting their use against intracellular pathogens like .
METHODS AND RESULTS
Herein, we synthesized amorphous and crystalline forms of aluminum hydroxide nanoparticles (AH nps) of 150-200 nm size range. Using protective antigen domain 4 (D4) as a model antigen, we demonstrated that both amorphous and crystalline forms of AH nps displayed enhanced antigen D4 uptake by THP1 cells as compared to commercial adjuvant aluminum hydroxide gel (AH gel). In a mouse model, both amorphous and crystalline AH nps triggered an enhanced D4-specific Th2- and Th1-type immune response and conferred superior protection against anthrax spore challenge as compared to AH gel. Physicochemical characterization of crystalline and amorphous AH nps revealed stronger antigen D4 binding and release than AH gel.
CONCLUSION
These results demonstrate that size and crystallinity of AH nps play important roles in mediating enhanced antigen presenting cells (APCs) activation and potentiating a strong antigen-specific immune response, and are critical parameters for the rational design of alum-based Th1-type adjuvant to induce a more balanced antigen-specific immune response.
Topics: Adjuvants, Immunologic; Aluminum Hydroxide; Animals; Anthrax; Anthrax Vaccines; Antigens, Bacterial; Bacterial Toxins; Cell Line; Disease Models, Animal; Dynamic Light Scattering; Female; Humans; Metal Nanoparticles; Mice; RAW 264.7 Cells; Spectroscopy, Fourier Transform Infrared; Th1 Cells
PubMed: 32021177
DOI: 10.2147/IJN.S219647 -
Journal of Proteomics Mar 2018Aluminum-based adjuvants are the most widely used adjuvants in human vaccines. A comprehensive understanding of the mechanism of action of aluminum adjuvants at the...
UNLABELLED
Aluminum-based adjuvants are the most widely used adjuvants in human vaccines. A comprehensive understanding of the mechanism of action of aluminum adjuvants at the molecular level, however, is still elusive. Here, we unravel the effects of aluminum hydroxide Al(OH) by a systems-wide analysis of the Al(OH)-induced monocyte response. Cell response analysis by cytokine release was combined with (targeted) transcriptome and full proteome analysis. Results from this comprehensive study revealed two novel pathways to become activated upon monocyte stimulation with Al(OH): the first pathway was IFNβ signaling possibly induced by DAMP sensing pathways like TLR or NOD1 activation, and second the HLA class I antigen processing and presentation pathway. Furthermore, known mechanisms of the adjuvant activity of Al(OH) were elucidated in more detail such as inflammasome and complement activation, homeostasis and HLA-class II upregulation, possibly related to increased IFNγ gene expression. Altogether, our study revealed which immunological pathways are activated upon stimulation of monocytes with Al(OH), refining our knowledge on the adjuvant effect of Al(OH) in primary monocytes.
SIGNIFICANCE
Aluminum salts are the most used adjuvants in human vaccines but a comprehensive understanding of the working mechanism of alum adjuvants at the molecular level is still elusive. Our Systems Vaccinology approach, combining complementary molecular biological, immunological and mass spectrometry-based techniques gave a detailed insight in the molecular mechanisms and pathways induced by Al(OH) in primary monocytes. Several novel immunological relevant cellular pathways were identified: type I interferon secretion potentially induced by TLR and/or NOD like signaling, the activation of the inflammasome and the HLA Class-I and Class-II antigen presenting pathways induced by IFNγ. This study highlights the mechanisms of the most commonly used adjuvant in human vaccines by combing proteomics, transcriptomics and cytokine analysis revealing new potential mechanisms of action for Al(OH).
Topics: Adjuvants, Immunologic; Aluminum Hydroxide; Antigen Presentation; Cytokines; Gene Expression Profiling; Humans; Immunity, Innate; Inflammation; Monocytes; Proteomics
PubMed: 29317357
DOI: 10.1016/j.jprot.2017.12.021