Outer membrane vesicles derived from Bordetella pertussis are potent adjuvant that drive Th1-biased response

For several years, we have been committed to exploring the potential of Bordetella pertussis-derived outer membrane vesicles (OMVBp) as a promising third-generation vaccine against the reemerging pertussis disease. The results of our preclinical trials not only confirm its protective capacity against B. pertussis infection but also set the stage for forthcoming human clinical trials. This study delves into the examination of OMVBp as an adjuvant. To accomplish this objective, we implemented a two-dose murine schedule to evaluate the specific immune response induced by formulations containing OMVBp combined with 3 heterologous immunogens: Tetanus toxoid (T), Diphtheria toxoid (D), and the SARS-CoV-2 Spike protein (S). The specific levels of IgG, IgG1, and IgG2a triggered by the different tested formulations were evaluated using ELISA in dose-response assays for OMVBp and the immunogens at varying levels. These assays demonstrated that OMVBp exhibits adjuvant properties even at the low concentration employed (1.5 μg of protein per dose). As this effect was notably enhanced at medium (3 μg) and high concentrations (6 μg), we chose the medium concentration to determine the minimum immunogen dose at which the OMV adjuvant properties are significantly evident. These assays demonstrated that OMVBp exhibits adjuvant properties even at the lowest concentration tested for each immunogen. In the presence of OMVBp, specific IgG levels detected for the lowest amount of antigen tested increased by 2.5 to 10 fold compared to those found in animals immunized with formulations containing adjuvant-free antigens (p<0.0001). When assessing the adjuvant properties of OMVBp compared to the widely recognized adjuvant alum, we detected similar levels of specific IgG against D, T and S for both adjuvants. Experiments with OMVs derived from E. coli (OMVE.coli) reaffirmed that the adjuvant properties of OMVs extend across different bacterial species. Nonetheless, it's crucial to highlight that OMVBp notably skewed the immune response towards a Th1 profile (p<0.05). These collective findings emphasize the dual role of OMVBp as both an adjuvant and modulator of the immune response, positioning it favorably for incorporation into combined vaccine formulations.

Aluminium in dermatology - Inside story of an innocuous metal

Aluminium, the third most abundant element in the earth's crust, was long considered virtually innocuous to humans but has gained importance in the recent past. Aluminium is ubiquitous in the environment, with various sources of exposure like cosmetics, the food industry, occupational industries, the medical field, transport and electronics. Aluminium finds its utility in various aspects of dermatology as an effective haemostatic agent, anti-perspirant and astringent. Aluminium has a pivotal role to play in wound healing, calciphylaxis, photodynamic therapy and vaccine immunotherapy with diagnostic importance in Finn chamber patch testing and confocal microscopy. The metal also finds significance in cosmetic procedures like microdermabrasion and as an Nd:YAG laser component. It is important to explore the allergic properties of aluminium, as in contact dermatitis and vaccine granulomas. The controversial role of aluminium in breast cancer and breast cysts also needs to be evaluated by further studies.

Leptospira Lipid A Is a Potent Adjuvant That Induces Sterilizing Immunity against Leptospirosis

Leptospirosis is a globally significant zoonotic disease. The current inactivated vaccine offers protection against specific serovars but does not provide complete immunity. Various surface antigens, such as Leptospira immunoglobulin-like proteins (LigA and LigB), have been identified as potential subunit vaccine candidates. However, these antigens require potent adjuvants for effectiveness. Bacterial lipopolysaccharides (LPSs), including lipid A, are a well-known immunostimulant, and clinical adjuvants often contain monophosphoryl lipid A (MPLA). Being less endotoxic, we investigated the adjuvant properties of lipid A isolated from L. interrogans serovar Pomona (PLA) in activating innate immunity and enhancing antigen-specific adaptive immune responses. PLA activated macrophages to a similar degree as MPLA, albeit at a higher dose, suggesting that it is less potent in stimulation than MPLA. Mice immunized with a variable portion of LigA (LAV) combined with alum and PLA (LAV-alum-PLA) exhibited significantly higher levels of LAV-specific humoral and cellular immune responses compared to alum alone but similar to those induced by alum-MPLA. The adjuvant activity of PLA resembles that of MPLA and is primarily achieved through the increased recruitment, activation, and uptake of antigens by innate immune cells. Furthermore, like MPLA, PLA formulation establishes a long-lasting memory response. Notably, PLA demonstrated superior potency than MPLA formulation and provided sterilizing immunity against the leptospirosis in a hamster model. Overall, our study sheds light on the adjuvant properties of Leptospira lipid A and offers promising avenues for developing LPS-based vaccines against this devastating zoonotic disease.

SARS-CoV-2 spike HexaPro formulated in aluminium hydroxide and administered in an accelerated vaccination schedule partially protects Syrian Hamsters against viral challenge despite low neutralizing antibody responses

SARS-CoV-2 continues to pose a threat to human health as new variants emerge and thus a diverse vaccine pipeline is needed. We evaluated SARS-CoV-2 HexaPro spike protein formulated in Alhydrogel^® (aluminium oxyhydroxide) in Syrian hamsters, using an accelerated two dose regimen (given 10 days apart) and a standard regimen (two doses given 21 days apart). Both regimens elicited spike- and RBD-specific IgG antibody responses of similar magnitude, but in vitro virus neutralization was low or undetectable. Despite this, the accelerated two dose regimen offered reduction in viral load and protected against lung pathology upon challenge with homologous SARS-CoV-2 virus (Wuhan-Hu-1). This highlights that vaccine-induced protection against SARS-CoV-2 disease can be obtained despite low neutralizing antibody levels and suggests that accelerated vaccine schedules may be used to confer rapid protection against SARS-CoV-2 disease.

Review: Unravelling the Role of DNA Sensing in Alum Adjuvant Activity

Public interest in vaccines is at an all-time high following the SARS-CoV-2 global pandemic. Currently, over 6 billion doses of various vaccines are administered globally each year. Most of these vaccines contain Aluminium-based adjuvants (alum), which have been known and used for almost 100 years to enhance vaccine immunogenicity. However, despite the historical use and importance of alum, we still do not have a complete understanding of how alum works to drive vaccine immunogenicity. In this article, we critically review studies investigating the mechanisms of action of alum adjuvants, highlighting some of the misconceptions and controversies within the area. Although we have emerged with a clearer understanding of how this ubiquitous adjuvant works, we have also highlighted some of the outstanding questions in the field. While these may seem mainly of academic interest, developing a more complete understanding of these mechanisms has the potential to rationally modify and improve the immune response generated by alum-adjuvanted vaccines.

Magnetic Field Effect on Coagulation Treatment of Wastewater Using Magnetite Rice Starch and Aluminium Sulfate

The use of synthetic coagulants to reduce suspended particles from drinkable water and wastewater is prompting new issues because it poses many health and environmental risks. Hence, improving the coagulation process using sophisticated nanotechnology with a magnetic field (MF) for quick recoverability emerges as being useful. In this study, the effects of magnetite rice starch (MS) and aluminum sulfate (alum) were investigated at a constant dose (3 g or 3000 mg/L) using a Jar test (six beakers) as potential low-cost coagulants for industrial wastewater treatment. At a high magnification of 1000× and a surface pore size of 298 µm, scanning electron microscopy and energy dispersive X-ray (SEM/EDX) analyses were utilized to elucidate the morphology of the coagulants. Coagulation was performed at 150 rpm (quick mixing) for 2 min, and 30 rpm (slow mixing) for 15 min. Thereafter, samples were allowed to settle (10-60 min) with and without MF. The findings showed more than 65% contaminants removal (turbidity and TSS) and 30% chemical oxygen demand (COD) removal using alum while MS showed 80% contaminants removal (turbidity and TSS) and 50% COD removal. MS showed an increase of more than 3% in contaminants removal (COD, turbidity, and TSS) when exposed to MF. As a result, the use of MS together with MF in water and wastewater treatment is anticipated as an environmentally benign and effective coagulant.

Thermophilic Filamentous Fungus C1-Cell-Cloned SARS-CoV-2-Spike-RBD-Subunit-Vaccine Adjuvanted with Aldydrogel(®)85 Protects K18-hACE2 Mice against Lethal Virus Challenge

SARS-CoV-2 is evolving with increased transmission, host range, pathogenicity, and virulence. The original and mutant viruses escape host innate (Interferon) immunity and adaptive (Antibody) immunity, emphasizing unmet needs for high-yield, commercial-scale manufacturing to produce inexpensive vaccines/boosters for global/equitable distribution. We developed DYAI-100A85, a SARS-CoV-2 spike receptor binding domain (RBD) subunit antigen vaccine expressed in genetically modified thermophilic filamentous fungus, Thermothelomyces heterothallica C1, and secreted at high levels into fermentation medium. The RBD-C-tag antigen strongly binds ACE2 receptors in vitro. Alhydrogel^®'85'-adjuvanted RDB-C-tag-based vaccine candidate (DYAI-100A85) demonstrates strong immunogenicity, and antiviral efficacy, including in vivo protection against lethal intranasal SARS-CoV-2 (D614G) challenge in human ACE2-transgenic mice. No loss of body weight or adverse events occurred. DYAI-100A85 also demonstrates excellent safety profile in repeat-dose GLP toxicity study. In summary, subcutaneous prime/boost DYAI-100A85 inoculation induces high titers of RBD-specific neutralizing antibodies and protection of hACE2-transgenic mice against lethal challenge with SARS-CoV-2. Given its demonstrated safety, efficacy, and low production cost, vaccine candidate DYAI-100 received regulatory approval to initiate a Phase 1 clinical trial to demonstrate its safety and efficacy in humans.

Antigen-adjuvant interactions, stability, and immunogenicity profiles of a SARS-CoV-2 receptor-binding domain (RBD) antigen formulated with aluminum salt and CpG adjuvants

Low-cost, refrigerator-stable COVID-19 vaccines will facilitate global access and improve vaccine coverage in low- and middle-income countries. To this end, subunit-based approaches targeting the receptor-binding domain (RBD) of SARS-CoV-2 Spike protein remain attractive. Antibodies against RBD neutralize SARS-CoV-2 by blocking viral attachment to the host cell receptor, ACE2. Here, a yeast-produced recombinant RBD antigen (RBD-L452K-F490W or RBD-J) was formulated with various combinations of aluminum-salt (Alhydrogel®, AH; AdjuPhos®, AP) and CpG 1018 adjuvants. We assessed the effect of antigen-adjuvant interactions on the stability and mouse immunogenicity of various RBD-J preparations. While RBD-J was 50% adsorbed to AH and <15% to AP, addition of CpG resulted in complete AH binding, yet no improvement in AP adsorption. ACE2 competition ELISA analyses of formulated RBD-J stored at varying temperatures (4, 25, 37°C) revealed that RBD-J was destabilized by AH, an effect exacerbated by CpG. DSC studies demonstrated that aluminum-salt and CpG adjuvants decrease the conformational stability of RBD-J and suggest a direct CpG-RBD-J interaction. Although AH+CpG-adjuvanted RBD-J was the least stable in vitro, the formulation was most potent at eliciting SARS-CoV-2 pseudovirus neutralizing antibodies in mice. In contrast, RBD-J formulated with AP+CpG showed minimal antigen-adjuvant interactions, a better stability profile, but suboptimal immune responses. Interestingly, the loss of in vivo potency associated with heat-stressed RBD-J formulated with AH+CpG after one dose was abrogated by a booster. Our findings highlight the importance of elucidating the key interrelationships between antigen-adjuvant interactions, storage stability, and in vivo performance to enable successful formulation development of stable and efficacious subunit vaccines.

Alum-anchored intratumoral retention improves the tolerability and antitumor efficacy of type I interferon therapies

Effective antitumor immunity in mice requires activation of the type I interferon (IFN) response pathway. IFNα and IFNβ therapies have proven promising in humans, but suffer from limited efficacy and high toxicity. Intratumoral IFN retention ameliorates systemic toxicity, but given the complexity of IFN signaling, it was unclear whether long-term intratumoral retention of type I IFNs would promote or inhibit antitumor responses. To this end, we compared the efficacy of IFNα and IFNβ that exhibit either brief or sustained retention after intratumoral injection in syngeneic mouse tumor models. Significant enhancement in tumor retention, mediated by anchoring these IFNs to coinjected aluminum-hydroxide (alum) particles, greatly improved both their tolerability and efficacy. The improved efficacy of alum-anchored IFNs could be attributed to sustained pleiotropic effects on tumor cells, immune cells, and nonhematopoietic cells. Alum-anchored IFNs achieved high cure rates of B16F10 tumors upon combination with either anti-PD-1 antibody or interleukin-2. Interestingly however, these alternative combination immunotherapies yielded disparate T cell phenotypes and differential resistance to tumor rechallenge, highlighting important distinctions in adaptive memory formation for combinations of type I IFNs with other immunotherapies.

Effect of Potassium Aluminum Sulfate Application on the Viability of Fibroblasts on a CAD-CAM Feldspathic Ceramic before and after Thermocycling

Potassium aluminum sulfate (alum) is a known adjuvant, which has been used as a mordant in textile industry for color fixation. This material has potential to be incorporated into dentistry for color stability, yet its toxicity first needs to be evaluated. The present study aimed to evaluate the cytotoxic potential of potassium aluminum sulfate (alum) on fibroblasts when applied onto feldspathic ceramic before and after thermocycling. Forty-eight feldspathic ceramic specimens were divided into four groups (FC: no alum application or thermocycling; FCT: thermocycling without alum application; FA: alum application without thermocycling; FAT: alum application and thermocycling) (n = 12). Cell viability was assessed by using a tetrazolium salt 3-[4,5-dimethylthiazol-2-yl]-2,5-diphnyltetrazolium bromide assay at 24 and 72 h, and cell cultures without any ceramic specimens served as control (C). One sample from each material group was further analyzed with energy dispersive X-ray spectroscopy (EDX). Cell viability at different time intervals within each group was analyzed with Friedman tests, while Kruskal−Wallis tests were used to compare the test groups within each time interval. Pairwise comparisons were further resolved by using Wilcoxon tests (a = 0.05). C had lower (p = 0.01) and FA had higher (p = 0.019) cell viability after 72 h. After 24 h, the highest cell viability was observed in C (p ≤ 0.036). After 72 h, the differences between C and FA, C and FAT, FC and FA, and FCT and FAT were nonsignificant (p > 0.05). Cell viability was not affected by alum application or thermocycling at any time interval (p ≥ 0.631). EDX analysis showed an increase in potassium concentration in FA and FAT when compared with FC and FCT. Regardless of the time interval, alum application onto feldspathic ceramic and thermocycling did not influence the cell viability.

Conversion of Geraniol into Useful Value-Added Products in the Presence of Catalysts of Natural Origin: Diatomite and Alum

This article presents research related to the transformation of geraniol (GA), leading to the formation of products with very valuable properties. In the planned method, heterogeneous catalysts of natural origin in the form of alum and diatomite were used as catalysts. Initially, the process which we investigated was the process of isomerization of GA, but it turned out during the studies that GA is also transformed in other reactions. Before catalytic tests, these two minerals were subjected to detailed instrumental analyses using the following methods: XRD, SEM/EDX, XRF and FTIR, which allowed to obtain their full morphological characteristics. During the catalytic tests, the influence of such relevant parameters on the GA transformations was determined: temperature from 80 to 150 °C, catalyst content from 5 to 15% by weight and the reaction time from 15 min to 24 h. The tests presented in the article were carried out under atmospheric pressure (in air) as well as without the use of a solvent. The optimal conditions for the transformations of GA were determined on the basis of its conversion and selectivities of transformation to the main products in the form of: beta-pinene (BP), 6,11-dimethyl-2,6,10-dodecatriene-1-ol (DC) and thumbergol (TH). The above products were formed with the highest selectivity, respectively: 100 mol%, 50 mol% and 52 mol%. The results of the syntheses showed that for GA the best transformation results were obtained at the temperature of 80 °C (for both tested catalysts), with the catalyst content of 1 wt % (for both tested catalysts) and for the reaction time of 1 h (for diatomite)) and 3 h (for alum).

Development of Novel Detection Method for Rutinosidase in Tartary Buckwheat (Fagopyrum tataricum Gaertn.)

Contamination of rutinosidase is a major problem for rutin-rich food due to the hydrolysis of the functional compound rutin and generation of strong bitterness caused by the hydrolyzed moiety quercetin. This problem sometimes occurs between the trace and normal rutinosidase Tartary buckwheat varieties. Here, we developed a simple and rapid method for rutinosidase detection in 'ripening seeds using UV light' and in 'dough using alum-flavonoid complexation' from Tartary buckwheat (Fagopyrum tataricum Gaertn.). Normal rutinosidase seeds can be distinguished from trace-rutinosidase mature seeds and ripening young seeds using a rutin solution by comparing the muddiness, which corresponds to quercetin generation. In dough, we detected a threefold relative increase in rutinosidase activity corresponding to 1% contamination of normal rutinosidase flour with trace-rutinosidase flour within 65 min. These methods do not require expensive apparatuses and toxic chemicals and are therefore promising for detecting and preventing contamination by rutinosidase, e.g., in food processing factories.

Structural Alterations of Antigens at the Material Interface: An Early Decision Toolbox Facilitating Safe-by-Design Nanovaccine Development

Nanomaterials have found extensive interest in the development of novel vaccines, as adjuvants and/or carriers in vaccination platforms. Conjugation of protein antigens at the particle surface by non-covalent adsorption is the most widely used approach in licensed particulate vaccines. Hence, it is essential to understand proteins' structural integrity at the material interface in order to develop safe-by-design nanovaccines. In this study, we utilized two model proteins, the wild-type allergen Bet v 1 and its hypoallergenic fold variant (BM4), to compare SiO2 nanoparticles with Alhydrogel® as particulate systems. A set of biophysical and functional assays including circular dichroism spectroscopy and proteolytic degradation was used to examine the antigens' structural integrity at the material interface. Conjugation of both biomolecules to the particulate systems decreased their proteolytic stability. However, we observed qualitative and quantitative differences in antigen processing concomitant with differences in their fold stability. These changes further led to an alteration in IgE epitope recognition. Here, we propose a toolbox of biophysical and functional in vitro assays for the suitability assessment of nanomaterials in the early stages of vaccine development. These tools will aid in safe-by-design innovations and allow fine-tuning the properties of nanoparticle candidates to shape a specific immune response.

Performance and Nanostructure Simulation of Phosphogypsum Modified by Sodium Carbonate and Alum

This paper presents a new modification of the nanostructure of CaSO₄·2H₂O crystals containing nanopores. This nanoporous structure was achieved in phosphogypsum samples that were modified by sodium carbonate and alum. The effects of sodium carbonate and alum on the properties of phosphogypsum were studied. X-ray diffraction (XRD) and scanning electron microscopy (SEM) methods were used to explore the micro-mechanism of the composite system. Subsequently, molecular dynamics simulations were used to study the nanopore structures of the modified CaSO₄·2H₂O. The results show that the addition of sodium carbonate and alum reduced the absolute dry density by 23.1% compared with the original phosphogypsum sample, with a bending strength of 2.1 MPa and compressive strength of 7.5 MPa. In addition, new hydration products, sodium sulfate and sodium aluminum sulfate, were formed in the sample doped with sodium carbonate and alum. A new nanostructure of CaSO₄·2H₂O crystal containing nanopores was formed. Molecular simulations show that the hydration products were responsible for the surface nanopore formation, which was the main factor leading to an increase in mechanical strength. The presented nanopore structure yields lightweight and high strength properties in the modified phosphogypsum.

Inhibition of elastase enhances the adjuvanticity of alum and promotes anti-SARS-CoV-2 systemic and mucosal immunity

We report that suppression of the serine protease elastase reshapes innate responses induced by injected vaccines containing alum adjuvant. This reprogramming improves the induction of protective antibodies in the bloodstream and stimulates innate signals, which support the development of antibody responses in mucosal tissues. Our findings identify elastase as the innate regulator that blunts the adjuvant activity of alum. They also demonstrate that vaccination via mucosal routes is not an absolute requirement for antibody responses in mucosal tissues and secretions. Supplementation of an alum-based vaccine containing SARS-CoV-2 spike protein subunit 1 as antigen increased anti–SARS-CoV-2 immunity in the blood and mucosal secretions in mice. Thus, this strategy could help in the development of future protein-based vaccines against SARS-CoV-2.

Alum, used as an adjuvant in injected vaccines, promotes T helper 2 (Th2) and serum antibody (Ab) responses. However, it fails to induce secretory immunoglobulin (Ig) A (SIgA) in mucosal tissues and is poor in inducing Th1 and cell-mediated immunity. Alum stimulates interleukin 1 (IL-1) and the recruitment of myeloid cells, including neutrophils. We investigated whether neutrophil elastase regulates the adjuvanticity of alum, and whether a strategy targeting neutrophil elastase could improve responses to injected vaccines. Mice coadministered a pharmacological inhibitor of elastase, or lacking elastase, developed high-affinity serum IgG and IgA antibodies after immunization with alum-adsorbed protein vaccines, including the spike protein of severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2). These mice also developed broader antigen-specific CD4⁺ T cell responses, including high Th1 and T follicular helper (Tfh) responses. Interestingly, in the absence of elastase activity, mucosal SIgA responses were induced after systemic immunization with alum as adjuvant. Importantly, lack or suppression of elastase activity enhanced the magnitude of anti–SARS-CoV-2 spike subunit 1 (S1) antibodies, and these antibodies reacted with the same epitopes of spike 1 protein as sera from COVID-19 patients. Therefore, suppression of neutrophil elastase could represent an attractive strategy for improving the efficacy of alum-based injected vaccines for the induction of broad immunity, including mucosal immunity.

SARS‑CoV-2 RBD219-N1C1: A yeast-expressed SARS-CoV-2 recombinant receptor-binding domain candidate vaccine stimulates virus neutralizing antibodies and T-cell immunity in mice

There is an urgent need for an accessible and low-cost COVID-19 vaccine suitable for low- and middle-income countries. Here, we report on the development of a SARS-CoV-2 receptor-binding domain (RBD) protein, expressed at high levels in yeast (Pichia pastoris), as a suitable vaccine candidate against COVID-19. After introducing two modifications into the wild-type RBD gene to reduce yeast-derived hyperglycosylation and improve stability during protein expression, we show that the recombinant protein, RBD219-N1C1, is equivalent to the wild-type RBD recombinant protein (RBD219-WT) in an in vitro ACE-2 binding assay. Immunogenicity studies of RBD219-N1C1 and RBD219-WT proteins formulated with Alhydrogel® were conducted in mice, and, after two doses, both the RBD219-WT and RBD219-N1C1 vaccines induced high levels of binding IgG antibodies. Using a SARS-CoV-2 pseudovirus, we further showed that sera obtained after a two-dose immunization schedule of the vaccines were sufficient to elicit strong neutralizing antibody titers in the 1:1,000 to 1:10,000 range, for both antigens tested. The vaccines induced IFN-γ IL-6, and IL-10 secretion, among other cytokines. Overall, these data suggest that the RBD219-N1C1 recombinant protein, produced in yeast, is suitable for further evaluation as a human COVID-19 vaccine, in particular, in an Alhydrogel® containing formulation and possibly in combination with other immunostimulants.

The Influence of Small Organic Molecules on Coagulation from the Perspective of Hydrolysis Competition and Crystallization

Most coagulation studies focus on pollutant removal or floc separation efficiency. However, to understand the mechanism of coagulation, it is necessary to explore the behavior of coagulation in terms of the interactions among the functional groups on the surface of the metal hydrolysis precipitates during the hydrolysis process. In this study, for the first time, aluminum sulfate (alum) was used to investigate such interactions over the whole process sequence of hydrolysis, coagulation, and crystallization with, and without (as a control), the presence of specific low molecular weight (LMW) (molecular weight < 1000 Da) organic compounds with different chemical bonds. It was observed that primary nanoparticles (NPs) of around 10 nm size were produced during the hydrolysis of alum. The presence of organic compounds was found to influence the coagulation performance by affecting the metal hydrolysis and the properties of the nanoparticles. At pH 7, ethylenediaminetetraacetic acid disodium salt (EDTA) delayed the time when the particles start to aggregate but increased the maximum size of the flocs, while citric acid caused the crystallization of amorphous hydrates and inhibited the coagulation performance. In contrast, glucose, benzoic acid (BEN), and tris(hydroxymethyl)aminomethane (THMAM) had no significant effect on the coagulation performance. Therefore, LMW organics can bond to the hydrolysis products of metal ions through key functional groups, such as carboxyl groups, and then affect the coagulation process. The experimental results show that the presence of LMW organics can change the surface properties and degree of crystallization of the primary NPs, thereby affecting the performance of coagulation.

Flocculation of Chlorella vulgaris with alum and pH adjustment

Microalgae, a group of photosynthetic microorganisms, are a promising feedstock for biodiesel production, but their biomass retrieval is a challenging task. Flocculation is a feasible method for dewatering and harvesting microalgae biomass. In the current study, the effect of alum flocculation on Chlorella vulgaris biomass retrieval has been studied. Alum structural changes with pH were led to a full factorial design to address the effect of this chemical structure changes at different pH values. It is observed that the best flocculation efficiency could be achieved in the natural pH value of C. vulgaris growth medium (8.2) with less than 0.5 g/L flocculant addition, which would lead to the flocculation efficiency of more than 90%. An ensemble architecture of neural networks successfully employed for flocculation modeling.

Short or Long Interval between Priming and Boosting: Does It Impact on the Vaccine Immunogenicity?

Characterizing the impact of the vaccination schedule on the induction of B and T cell immune responses is critical for improving vaccine immunogenicity. Here we compare the effect of a short (4 weeks) or a long (18 weeks) interval between priming and boosting in mice, using a model vaccine formulation based on the chimeric tuberculosis vaccine antigen H56 combined with alum. While no significant difference was observed in serum antigen-specific IgG response and the induction of antigen-specific T follicular helper cells into draining lymph nodes after the two immunization schedules, a longer interval between priming and boosting elicited a higher number of germinal center-B cells and H56-specific antibody-secreting cells and modulated the effector function of reactivated CD4+ T cells. These data show that the scheduling of the booster immunization could affect the immune response elicited by vaccination modulating and improving the immunogenicity of the vaccine.

PEGylated single-walled carbon nanotubes as co-adjuvants enhance expression of maturation markers in monocyte-derived dendritic cells

Aim: This study investigated the application of phospholipid-PEGylated single-walled carbon nanotubes (PL-PEG-SWCNTs) as a safe co-adjuvant for the commercial recombinant hepatitis B virus vaccine to enhance induction of monocyte-derived dendritic cells (MDDCs) differentiation and activation in vitro as an immune response initiator cell to prompt a long-term immune response after a single dose injection. Methods: Immature MDDCs were exposed to PL-PEG-SWCNTs alone and in combination with hepatitis B vaccine. Results & conclusion: Study results confirm the enhanced expression of maturation markers in human immature MDDCs after PL-PEG-SWCNT exposure. The results suggest that PL-PEG-SWCNT is an efficient co-adjuvant for the commercial recombinant hepatitis B virus vaccine to enhance dendritic cell response stimulation in vitro.

Aluminum Adjuvant Improves Survival Via NLRP3 Inflammasome and Myeloid Non-Granulocytic Cells in a Murine Model of Neonatal Sepsis

ABSTRACT

Neonatal sepsis leads to significant morbidity and mortality with the highest risk of death occurring in preterm (<37 weeks) and low birth weight (<2,500 g) infants. The neonatal immune system is developmentally immature with well-described defects in innate and adaptive immune responses. Immune adjuvants used to enhance the vaccine response have emerged as potential therapeutic options, stimulating non-specific immunity and preventing sepsis mortality. Aluminum salts ("alum") have been used as immune adjuvants for over a century, but their mechanism of action remains poorly understood. This study aims to identify potential mechanisms by which pretreatment with alum induces host protective immunity to polymicrobial sepsis in neonatal mice. Utilizing genetic and cell-depletion studies, we demonstrate here that the prophylactic administration of aluminum adjuvants in neonatal mice improves sepsis survival via activation of the nucleotide oligomerization domain-like receptor family, pyrin-domain-containing 3 inflammasome and dendritic cell activation. Furthermore, this beneficial effect is dependent on myeloid, non-granulocytic Gr1-positive cells, and MyD88-signaling pathway activation. These findings suggest a promising therapeutic role for aluminum-based vaccine adjuvants to prevent development of neonatal sepsis and improve mortality in this highly vulnerable population.

Coagulation Treatment of Wastewater: Kinetics and Natural Coagulant Evaluation

In this study, three coagulants (ferromagnetite (F), alum (A), and eggshells (E)) and their hybrids (FA, FE, and FEA) were investigated as possible cost-effective coagulants for the treatment of industrial wastewater. Scanning electron microscopy (SEM) coupled with energy-dispersive X-ray (EDX) was used to characterize the morphological and elemental compositions of the coagulants. The effects of coagulant dosage (10–60 mg/L) and settling time were investigated for the removal of turbidity, color, and total suspended solids. A jar tester (JTL6) operating at conditions of 150 rpm for 2 min (rapid mixing) and 30 rpm for 15 min (slow mixing) was employed. Results from the characterized supernatant showed about 80% removal of the contaminants. The prospects of F were proven to be the most effective as compared to the binary (FA > FE) and the ternary hybridized (FEA) coagulants. At an optimum dosage and settling time of 20 mg/L and 30 min, respectively, the treatability performance of F was clearly proven to be viable for wastewater treatment.

Challenges and Opportunities of Biocoagulant/Bioflocculant Application for Drinking Water and Wastewater Treatment and Its Potential for Sludge Recovery

The utilization of metal-based conventional coagulants/flocculants to remove suspended solids from drinking water and wastewater is currently leading to new concerns. Alarming issues related to the prolonged effects on human health and further pollution to aquatic environments from the generated nonbiodegradable sludge are becoming trending topics. The utilization of biocoagulants/bioflocculants does not produce chemical residue in the effluent and creates nonharmful, biodegradable sludge. The conventional coagulation-flocculation processes in drinking water and wastewater treatment, including the health and environmental issues related to the utilization of metal-based coagulants/flocculants during the processes, are discussed in this paper. As a counterpoint, the development of biocoagulants/bioflocculants for drinking water and wastewater treatment is intensively reviewed. The characterization, origin, potential sources, and application of this green technology are critically reviewed. This review paper also provides a thorough discussion on the challenges and opportunities regarding the further utilization and application of biocoagulants/bioflocculants in water and wastewater treatment, including the importance of the selection of raw materials, the simplification of extraction processes, the application to different water and wastewater characteristics, the scaling up of this technology to a real industrial scale, and also the potential for sludge recovery by utilizing biocoagulants/bioflocculants in water/wastewater treatment.

Particulate Alum via Pickering Emulsion for an Enhanced COVID-19 Vaccine Adjuvant

For rapid response against the prevailing COVID-19 (coronavirus disease 19), it is a global imperative to exploit the immunogenicity of existing formulations for safe and efficient vaccines. As the most accessible adjuvant, aluminum hydroxide (alum) is still the sole employed adjuvant in most countries. However, alum tends to attach on the membrane rather than entering the dendritic cells (DCs), leading to the absence of intracellular transfer and process of the antigens, and thus limits T-cell-mediated immunity. To address this, alum is packed on the squalene/water interphase is packed, forming an alum-stabilized Pickering emulsion (PAPE). "Inheriting" from alum and squalene, PAPE demonstrates a good biosafety profile. Intriguingly, with the dense array of alum on the oil/water interphase, PAPE not only adsorbs large quantities of SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) antigens, but also harbors a higher affinity for DC uptake, which provokes the uptake and cross-presentation of the delivered antigens. Compared with alum-treated groups, more than six times higher antigen-specific antibody titer and three-fold more IFN-γ-secreting T cells are induced, indicating the potent humoral and cellular immune activations. Collectively, the data suggest that PAPE may provide potential insights toward a safe and efficient adjuvant platform for the enhanced COVID-19 vaccinations.

Particulate Alum via Pickering Emulsion for an Enhanced COVID-19 Vaccine Adjuvant

For rapid response against the prevailing COVID-19 (coronavirus disease 19), it is a global imperative to exploit the immunogenicity of existing formulations for safe and efficient vaccines. As the most accessible adjuvant, aluminum hydroxide (alum) is still the sole employed adjuvant in most countries. However, alum tends to attach on the membrane rather than entering the dendritic cells (DCs), leading to the absence of intracellular transfer and process of the antigens, and thus limits T-cell-mediated immunity. To address this, alum is packed on the squalene/water interphase is packed, forming an alum-stabilized Pickering emulsion (PAPE). "Inheriting" from alum and squalene, PAPE demonstrates a good biosafety profile. Intriguingly, with the dense array of alum on the oil/water interphase, PAPE not only adsorbs large quantities of SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) antigens, but also harbors a higher affinity for DC uptake, which provokes the uptake and cross-presentation of the delivered antigens. Compared with alum-treated groups, more than six times higher antigen-specific antibody titer and three-fold more IFN-γ-secreting T cells are induced, indicating the potent humoral and cellular immune activations. Collectively, the data suggest that PAPE may provide potential insights toward a safe and efficient adjuvant platform for the enhanced COVID-19 vaccinations.

Vaccine Adjuvants Differentially Affect Kinetics of Antibody and Germinal Center Responses

Aluminum salts and squalene based oil-in-water emulsions (SE) are widely used adjuvants in licensed vaccines, yet their mechanisms are not fully known. Here we report that induction of antibody responses displays different kinetics dependent on the adjuvant used. SE facilitated a rapid antibody response in contrast to aluminum hydroxide (AH) and the depot-forming cationic liposome-based adjuvant (CAF01). Antigen given with the SE adjuvant rapidly reached follicular B cells in the draining lymph node, whereas antigen formulated in AH or CAF01 remained at the site of injection as a depot. Removal of the injection site early after immunization abrogated antibody responses only when antigen was given in the depot-forming adjuvants. Despite initial delays in B cell activation and germinal center (GC) formation when antigen was given in depot-forming adjuvants, the antibody levels reached higher magnitudes than when the antigen was formulated in SE. This study demonstrates that the kinetic aspect of antibody responses is critical in adjuvant benchmarking and suggests that the optimal vaccination regime depends on the adjuvant used.

Activation of the NLRP3 Inflammasome by Particles from the Echinococcus granulosus Laminated Layer

The interaction of dendritic cells and macrophages with a variety of rigid noncellular particles triggers activation of the NLRP3 inflammasome and consequent secretion of interleukin 1β (IL-1β). Noncellular particles can also be generated in the context of helminth infection, since these large pathogens often shed their outermost structures during growth and/or molting. One such structure is the massive, mucin-based, soft, flexible laminated layer (LL), which protects the larval stages of cestodes of the genus Echinococcus.

The interaction of dendritic cells and macrophages with a variety of rigid noncellular particles triggers activation of the NLRP3 inflammasome and consequent secretion of interleukin 1β (IL-1β). Noncellular particles can also be generated in the context of helminth infection, since these large pathogens often shed their outermost structures during growth and/or molting. One such structure is the massive, mucin-based, soft, flexible laminated layer (LL), which protects the larval stages of cestodes of the genus Echinococcus. We show that particles from the Echinococcus granulosus LL (pLL) trigger NLRP3- and caspase-1-dependent IL-1β in lipopolysaccharide (LPS)-primed mouse bone marrow-derived dendritic cells (BMDC). This response can be elicited by pLL too large for phagocytosis and nonetheless requires actin dynamics, Syk, and phosphatidylinositol 3-kinase (PI3K). These three requirements had already been observed in our previous study on the alteration by pLL of CD86, CD40, IL-10, and IL-12 responses to LPS in BMDC; however, we now show that these alterations are independent of NLRP3 and caspase-1. In other words, an initial interaction with particles requiring actin dynamics, Syk, and PI3K, but not phagocytosis, elicits both NLRP3-dependent and NLRP3-independent responses. Intraperitoneal injection of pLL induced IL-1β, suggesting that contact with LL materials induces IL-1β in the E. granulosus infection setting. Our results extend our understanding of NLRP3 inflammasome activation by noncellular particulate materials both to helminth-derived materials and to flexible/soft materials.

NY-ESO-1 Protein Vaccine Combining Alum, CpG ODN, and HH2 Complex Adjuvant Induces Protective and Therapeutic Anti-Tumor Responses in Murine Multiple Myeloma

Background

NY-ESO-1 is an ideal target for multiple myeloma immunotherapy. Alum, CpG ODN and HH2 complex is a safe and effective adjuvant for cancer vaccine.

Methods

We constructed NY-ESO-1 protein vaccine combined with alum, CpG ODN, and HH2 complex adjuvant to immunize the BALB/c mice inoculated with NS-1 murine multiple myeloma cells. Then, we determined the immunogenicity and anti-tumor effects in prophylactic and therapeutic models by analyzing the NY-ESO-1 antibody titer, evaluating IL4/INF-γ expression, and assessing cytotoxic T lymphocytes activities. The side-effects of vaccines were also evaluated.

Results

The group of NY-ESO-1 protein vaccine combining alum, CpG ODN, and HH2 complex adjuvant is more capable of stimulating both humoral and cellular tumor-specific immune responses to prolong the survival of the mice and inhibit tumor growth in prophylactic and therapeutic immunotherapy. The marked side-effects were not detected in immunized mice.

Discussion

The results suggest that alum, CpG ODN, and HH2 complex as a novel immune adjuvant combined cancer vaccine could improve the immunity efficiency in a murine multiple myeloma model.

Rotavirus Inner Capsid VP6 Acts as an Adjuvant in Formulations with Particulate Antigens Only

Novel adjuvants present a concern for adverse effects, generating a need for alternatives. Rotavirus inner capsid VP6 protein could be considered a potential candidate, due to its ability to self-assemble into highly immunogenic nanospheres and nanotubes. These nanostructures exhibit immunostimulatory properties, which resemble those of traditional adjuvants, promoting the uptake and immunogenicity of the co-administered antigens. We have previously elucidated an adjuvant effect of VP6 on co-delivered norovirus and coxsackievirus B1 virus-like particles, increasing humoral and cellular responses and sparing the dose of co-delivered antigens. This study explored an immunostimulatory effect of VP6 nanospheres on smaller antigens, P particles formed by protruding domain of a norovirus capsid protein and a short peptide, extracellular matrix protein (M2e) of influenza A virus. VP6 exhibited a notable improving impact on immune responses induced by P particles in immunized mice, including systemic and mucosal antibody and T cell responses. The adjuvant effect of VP6 nanospheres was comparable to the effect of alum, except for induction of superior mucosal and T cell responses when P particles were co-administered with VP6. However, unlike alum, VP6 did not influence M2e-specific immune responses, suggesting that the adjuvant effect of VP6 is dependent on the particulate nature of the co-administered antigen.

Mechanisms of Particles in Sensitization, Effector Function and Therapy of Allergic Disease

Humans have always been in contact with natural airborne particles from many sources including biologic particulate matter (PM) which can exhibit allergenic properties. With industrialization, anthropogenic and combustion-derived particles have become a major fraction. Currently, an ever-growing number of diverse and innovative materials containing engineered nanoparticles (NPs) are being developed with great expectations in technology and medicine. Nanomaterials have entered everyday products including cosmetics, textiles, electronics, sports equipment, as well as food, and food packaging. As part of natural evolution humans have adapted to the exposure to particulate matter, aiming to protect the individual's integrity and health. At the respiratory barrier, complications can arise, when allergic sensitization and pulmonary diseases occur in response to particle exposure. Particulate matter in the form of plant pollen, dust mites feces, animal dander, but also aerosols arising from industrial processes in occupational settings including diverse mixtures thereof can exert such effects. This review article gives an overview of the allergic immune response and addresses specifically the mechanisms of particulates in the context of allergic sensitization, effector function and therapy. In regard of the first theme (i), an overview on exposure to particulates and the functionalities of the relevant immune cells involved in allergic sensitization as well as their interactions in innate and adaptive responses are described. As relevant for human disease, we aim to outline (ii) the potential effector mechanisms that lead to the aggravation of an ongoing immune deviation (such as asthma, chronic obstructive pulmonary disease, etc.) by inhaled particulates, including NPs. Even though adverse effects can be exerted by (nano)particles, leading to allergic sensitization, and the exacerbation of allergic symptoms, promising potential has been shown for their use in (iii) therapeutic approaches of allergic disease, for example as adjuvants. Hence, allergen-specific immunotherapy (AIT) is introduced and the role of adjuvants such as alum as well as the current understanding of their mechanisms of action is reviewed. Finally, future prospects of nanomedicines in allergy treatment are described, which involve modern platform technologies combining immunomodulatory effects at several (immuno-)functional levels.

Controlling timing and location in vaccines

Vaccines are one of the most powerful technologies supporting public health. The adaptive immune response induced by immunization arises following appropriate activation and differentiation of T and B cells in lymph nodes. Among many parameters impacting the resulting immune response, the presence of antigen and inflammatory cues for an appropriate temporal duration within the lymph nodes, and further within appropriate subcompartments of the lymph nodes– the right timing and location– play a critical role in shaping cellular and humoral immunity. Here we review recent advances in our understanding of how vaccine kinetics and biodistribution impact adaptive immunity, and the underlying immunological mechanisms that govern these responses. We discuss emerging approaches to engineer these properties for future vaccines, with a focus on subunit vaccines.

Nanotechnology-Based Vaccines for Allergen-Specific Immunotherapy: Potentials and Challenges of Conventional and Novel Adjuvants under Research

The increasing prevalence of allergic diseases demands efficient therapeutic strategies for their mitigation. Allergen-specific immunotherapy (AIT) is the only causal rather than symptomatic treatment method available for allergy. Currently, AIT is being administered using immune response modifiers or adjuvants. Adjuvants aid in the induction of a vigorous and long-lasting immune response, thereby improving the efficiency of AIT. The successful development of a novel adjuvant requires a thorough understanding of the conventional and novel adjuvants under development. Thus, this review discusses the potentials and challenges of these adjuvants and their mechanism of action. Vaccine development based on nanoparticles is a promising strategy for AIT, due to their inherent physicochemical properties, along with their ease of production and ability to stimulate innate immunity. Although nanoparticles have provided promising results as an adjuvant for AIT in in vivo studies, a deeper insight into the interaction of nanoparticle-allergen complexes with the immune system is necessary. This review focuses on the methods of harnessing the adjuvant effect of nanoparticles by detailing the molecular mechanisms underlying the immune response, which includes allergen uptake, processing, presentation, and induction of T cell differentiation.

Optimization of an Experimental Vaccine To Prevent Escherichia coli Urinary Tract Infection

Urinary tract infections (UTI) affect half of all women at least once during their lifetime. The rise in the numbers of extended-spectrum beta-lactamase-producing strains and the potential for carbapenem resistance within uropathogenic Escherichia coli (UPEC), the most common causative agent of UTI, create an urgent need for vaccine development. Intranasal immunization of mice with UPEC outer membrane iron receptors FyuA, Hma, IreA, and IutA, conjugated to cholera toxin, provides protection in the bladder or kidneys under conditions of challenge with UPEC strain CFT073 or strain 536. On the basis of these data, we sought to optimize the vaccination route (intramuscular, intranasal, or subcutaneous) in combination with adjuvants suitable for human use, including aluminum hydroxide gel (alum), monophosphoryl lipid A (MPLA), unmethylated CpG synthetic oligodeoxynucleotides (CpG), polyinosinic:polycytidylic acid (polyIC), and mutated heat-labile E. coli enterotoxin (dmLT). Mice intranasally vaccinated with dmLT-IutA and dmLT-Hma displayed significant reductions in bladder colonization (86-fold and 32-fold, respectively), with 40% to 42% of mice having no detectable CFU. Intranasal vaccination of mice with CpG-IutA and polyIC-IutA significantly reduced kidney colonization (131-fold) and urine CFU (22-fold), respectively. dmLT generated the most consistently robust antibody response in intranasally immunized mice, while MPLA and alum produced greater concentrations of antigen-specific serum IgG with intramuscular immunization. On the basis of these results, we conclude that intranasal administration of Hma or IutA formulated with dmLT adjuvant provides the greatest protection from UPEC UTI. This report advances our progress toward a vaccine against uncomplicated UTI, which will significantly improve the quality of life for women burdened by recurrent UTI and enable better antibiotic stewardship.IMPORTANCE Urinary tract infections (UTI) are among the most common bacterial infection in humans, affecting half of all women at least once during their lifetimes. The rise in antibiotic resistance and health care costs emphasizes the need to develop a vaccine against the most common UTI pathogen, Escherichia coli Vaccinating mice intranasally with a detoxified heat-labile enterotoxin and two surface-exposed receptors, Hma or IutA, significantly reduced bacterial burden in the bladder. This work highlights progress in the development of a UTI vaccine formulated with adjuvants suitable for human use and antigens that encode outer membrane iron receptors required for infection in the iron-limited urinary tract.

Alum impairs tolerogenic properties induced by allergoid-mannan conjugates inhibiting mTOR and metabolic reprogramming in human DCs

Background

Polymerized allergoids conjugated to mannan (PM) are suitable vaccines for allergen‐specific immunotherapy (AIT). Alum remains the most widely used adjuvant in AIT, but its way of action is not completely elucidated. The better understanding of the mechanisms underlying alum adjuvanticity could help to improve AIT vaccine formulations.

Objective

We sought to investigate the potential influence of alum in the tolerogenic properties imprinted by PM at the molecular level.

Methods

Flow cytometry, ELISAs, cocultures, intracellular staining and suppression assays were performed to assess alum and PM effects in human dendritic cells (DCs). BALB/c mice were immunized with PM alone or adsorbed to alum. Allergen‐specific antibodies, splenocyte cytokine production and splenic forkhead box P3 (FOXP3)⁺ regulatory T (Treg) cells were quantified. Metabolic and immune pathways were also studied in human DCs.

Results

Alum decreases PD‐L1 expression and IL‐10 production induced by PM in human DCs and increases pro‐inflammatory cytokine production. Alum impairs PM‐induced functional FOXP3⁺ Treg cells and promotes Th1/Th2/Th17 responses. Subcutaneous immunization of mice with PM plus alum inhibits in vivo induction of Treg cells promoted by PM without altering the capacity to induce functional allergen‐specific blocking antibodies. Alum inhibits mTOR activation and alters metabolic reprogramming by shifting glycolytic pathways and inhibiting reactive oxygen species (ROS) production in PM‐activated DCs, impairing their capacity to generate functional Treg cells.

Conclusion

We uncover novel mechanisms by which alum impairs the tolerogenic properties induced by PM, which might well contribute to improve the formulation of novel vaccines for AIT.

Activation of Human Monocytes by Colloidal Aluminum Salts

Subunit vaccines often contain colloidal aluminum salt-based adjuvants to activate the innate immune system. These aluminum salts consist of micrometer-sized aggregates. It is well-known that particle size affects the adjuvant effect of particulate adjuvants. In this study, the activation of human monocytes by hexagonal-shaped gibbsite (ø = 210 ± 40 nm) and rod-shaped boehmite (ø = 83 ± 827 nm) was compared with classical aluminum oxyhydroxide adjuvant (alum). To this end, human primary monocytes were cultured in the presence of alum, gibbsite, or boehmite. The transcriptome and proteome of the monocytes were investigated by using quantitative polymerase chain reaction and mass spectrometry. Human monocytic THP-1 cells were used to investigate the effect of the particles on cellular maturation, differentiation, activation, and cytokine secretion, as measured by flow cytometry and enzyme-linked immunosorbent assay. Each particle type resulted in a specific gene expression profile. IL-1ß and IL-6 secretion was significantly upregulated by boehmite and alum. Of the 7 surface markers investigated, only CD80 was significantly upregulated by alum and none by gibbsite or boehmite. Gibbsite hardly activated the monocytes. Boehmite activated human primary monocytes equally to alum, but induced a much milder stress-related response. Therefore, boehmite was identified as a promising adjuvant candidate.

The Combination Vaccine Adjuvant System Alum/c-di-AMP Results in Quantitative and Qualitative Enhanced Immune Responses Post Immunization

The development of new effective vaccines strongly depends on adjuvants and formulations able to stimulate not only strong humoral responses against a certain pathogen but also effector as well as memory CD4+ and CD8+ T cells (Dubensky et al., 2013). However, the majority of vaccines licensed for human use or currently under clinical investigation fail to stimulate efficient cellular responses. For example, vaccines against hepatitis B virus (HBV), human papillomavirus (HPV), diphtheria, tetanus and influenza are usually administered by intramuscular (i.m.) injection and contain aluminum salts (alum) as adjuvant. Alum has been shown to stimulate Th2 immune cells resulting in increased production of antigen-specific antibodies but to be incapable of stimulating robust Th1 or cytotoxic responses. To overcome such limitations recent research has focused on the development of adjuvant combinations (e.g., MF59, AS03 or AS04) to not only further strengthen antigen-specific immune responses but to also allow their modulation. We have shown previously that bis-(3',5')-cyclic dimeric adenosine monophosphate (c-di-AMP) constitutes a promising adjuvant candidate stimulating both effective Th1/Th2 and cytotoxic immune responses when included in mucosal or parenteral vaccine formulations. In the present work we demonstrate that c-di-AMP can be also combined with other adjuvants like alum resulting in increases in not only humoral responses but more striking also in cellular immune responses. This leads to improved vaccine efficacy against intracellular pathogens.

A Strong Humoral Immune Response Induced by a Vaccine Formulation Containing rSm29 Adsorbed to Alum Is Associated With Protection Against Schistosoma mansoni Reinfection in Mice

The helminth Schistosoma mansoni is one of main causes of human schistosomiasis, a health and economic concern in some of the world's poorest countries. Current treatment regimens can lead to serious side effects and are not suitable for breastfeeding mothers. As such, efforts have been undertaken to develop a vaccine to prevent infection. Of these, Sm29 is a promising candidate that has been associated with resistance to infection/reinfection in humans and mice. Its ability to induce resistance to reinfection has also been recently demonstrated using a vaccine formulation containing Freund's adjuvant. However, Freund's adjuvant is unsuitable for use in human vaccines. We therefore evaluated the ability of Sm29 to induce protection against S. mansoni reinfection when formulated with either alum or MPLA as an adjuvant, both approved for human use. Our data demonstrate that, in contrast to Sm29 with MPLA, Sm29 with alum reduced parasite burden after reinfection compared to a control. We next investigated whether the immune response was involved in creating the differences between the protective (Sm29Alum) and non-protective (Sm29MPLA) vaccine formulations. We observed that both formulations induced a similar mixed-profile immune response, however, the Sm29 with alum formulation raised the levels of antibodies against Sm29. This suggests that there is an association between a reduction in worm burden and parasite-specific antibodies. In summary, our data show that Sm29 with an alum adjuvant can successfully protect against S. mansoni reinfection in mice, indicating a potentially effective vaccine formulation that could be applied in humans.

From mine to apothecary: an archaeo-biomedical approach to the study of the Greco-Roman lithotherapeutics industry

Western biomedicine has only partially developed its own tradition of mineral medicinals (lithotherapeutics), at least compared to botanicals. This is perhaps because these minerals were site-specific, and fundamental information associated with the empirical processes of mineral extraction, beneficiation, storage, trade and preparation was not widely available. In other words, there are many and serious breaks in the multi-link chain from mine to apothecary. This long-term investigation aims to rebuild this chain, on a mineral-by-mineral basis, by pulling together the extant documentary record, material culture, mineralogy, geochemistry and microbial ecology, as well as by testing against known pathogens as an indicator of their antimicrobial activity. Critical to understanding the nature and efficacy of lithotherapeutics is the recognition that these materials need to be investigated simultaneously at two levels: the empirical (ancient sources and practices); and the biomedical (application of physical and biological sciences). Both approaches require the same starting point, namely the field (mine or quarry) and in particular the 'point of contact' (relationship) between minerals and their microbiome.

Antigen phagocytosis by B cells is required for a potent humoral response

Successful vaccines rely on activating a functional humoral response that results from promoting a proper germinal center (GC) reaction. Key in this process is the activation of follicular B cells that need to acquire antigens and to present them to cognate CD4 T cells. Here, we report that follicular B cells can phagocytose large antigen‐coated particles, a process thought to be exclusive of specialized antigen‐presenting cells such as macrophages and dendritic cells. We show that antigen phagocytosis by B cells is BCR‐driven and mechanistically dependent on the GTPase RhoG. Using Rhog^−/− mice, we show that phagocytosis of antigen by B cells is important for the development of a strong GC response and the generation of high‐affinity class‐switched antibodies. Importantly, we show that the potentiation effect of alum, a common vaccine adjuvant, requires direct phagocytosis of alum–antigen complexes by B cells. These data suggest a new avenue for vaccination approaches by aiming to deliver 1–3 μm size antigen particles to follicular B cells.

Formulation of chitosan with the polyepitope HIV-1 protein candidate vaccine efficiently boosts cellular immune responses in mice

Human immunodeficiency virus-1 (HIV-1) continues to be a major global public health issue and priority. Despite the variety of antiretroviral therapies, it seems that an effective vaccine against HIV-1 is still very necessary. An ideal HIV-1 vaccine should be able to elicit both humoral and cellular immunities. In this respect, polyepitope vaccines, incorporated from several conserved regions of HIV-1 proteins, have received much attention recently. Herein, the immunogenicity of the HIV-1 polyepitope protein-based candidate vaccines was evaluated in BALB/c mice. Following the plasmid (pET23a-HIV-1-tat/pol/gag/env) preparation and transformation, the recombinant protein expression was optimized in Escherichia coli BL21 (DE3) host cells. After the HIV-1-top4 protein purification, chitosan and alum adjuvants were added to the vaccines formulations to reinforce the immunogenicity of the candidate vaccines. Mice were subcutaneously immunized three times at 2-week intervals with the candidate vaccines and the elicitation of both humoral and cellular immune responses were investigated. Taken together, the results showed that chitosan adjuvanted candidate vaccine conferred a stronger immunogenicity and elicited higher cellular responses than other candidate vaccines (P < 0.05). Thereby, it seems that co-utilizing of potent adjuvants with the HIV-1 polyepitope protein vaccines can help to open new avenues for strategies for HIV/AIDS vaccine design.

Stability of an aluminum salt-adjuvanted protein D-conjugated pneumococcal vaccine after exposure to subzero temperatures

Accidental exposure of a vaccine containing an aluminum-salt adjuvant to temperatures below 0°C in the cold chain can lead to freeze damage. Our study evaluated the potential for freeze damage in a licensed aluminum-salt-containing protein-D-conjugated pneumococcal vaccine (PHiD-CV; Synflorix, GSK) in conditions that included static storage, single subzero-temperature excursions, and simulated air-freight transportation. Several parameters were assessed including freezing at subzero temperatures, aluminum-salt-particle size, antigen integrity and immunogenicity in the mouse. The suitability of the WHO's shake test for identifying freeze-damaged vaccines was also assessed. During subzero-temperature excursions, the mean temperatures at which PHiD-CV froze (-16.7°C to -18.1°C) appeared unaffected by the type of vaccine container (two-dose or four-dose vial, or single-dose syringe), vaccine batch, rotational agitation, or the rate of temperature decline (-0.5 to -10°C/hour). At constant subzero temperature and in simulated air-freight transportation, the freezing of PHiD-CV appeared to be promoted by vibration. At -5°C, no PHiD-CV sample froze in static storage (>1 month), whereas when subjected to vibration, a minority of samples froze (7/21, 33%) within 18 hours. At -8°C with vibration, nearly all (5/6, 83%) samples froze. In these vibration regimes, the shake test identified most samples that froze (10/12, 93%) except two in the -5°C regime. Nevertheless, PHiD-CV-antigen integrity appeared unaffected by freezing up to -20°C or by vibration. And although aluminum-salt-particle size was increased only by freezing at -20°C, PHiD-CV immunogenicity appeared only marginally affected by freezing at -20°C. Therefore, our study supports the use of the shake test to exclude freeze-damaged PHiD-CV in the field.

Effect of apoptosis-associated speck-like protein containing a caspase recruitment domain on vaccine efficacy: Overcoming the effects of its deficiency with aluminum hydroxide adjuvant

Host factors such as nutritional status and immune cell state are important for vaccine efficacy. Inflammasome activation may be important for triggering vaccine-induced humoral and cell-mediated immune responses. Formulations with alum as a typical adjuvant to overcome the effects of host factors have recently been shown to induce inflammasome activation, which augments vaccine efficacy. Apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) is one of the main components of inflammasomes, but it is not clear whether ASC affects the vaccine-induced immune response. Herein, we used two types of vaccines: inactivated influenza vaccine not formulated with alum, and HPV vaccine formulated with alum. We gave the vaccines to ASC knockout (ASC^-/- ) mice to investigate the role of ASC in vaccine efficacy. Influenza vaccine-immunized ASC^-/- mice did not show antibody titers in week 2 after the first vaccination. After boosting, the antibody titer in ASC^-/- mice was about half that in wild type (WT) mice. Furthermore, a cytotoxic T-lymphocyte response against influenza vaccine was not induced in ASC^-/- mice. Therefore, vaccinated ASC^-/- mice did not show effective protection against viral challenge. ASC^-/- mice immunized with alum-formulated HPV vaccine showed similar antibody titers and T-cell proliferation compared with immunized WT mice. However, the HPV vaccine without alum induced up to threefold lower titers of HPV-specific antibody titers in ASC^-/- mice compared with those in WT mice. These findings suggest that alum in vaccine can overcome the ASC-deficient condition.

A Study on Growth Performance of Ducks Fed Diets with Different Types of Sipjeondaebo-Tang Byproduct Meal and Red Ginseng Marc with Fermented Red Koji and Ammonia Fluxes in Duck Litter using Alum or Aluminum Chloride

The aims of the present study were to investigate the growth performance of ducks fed diets with different types of Sipjeondaebo-tang (ST) byproduct meal and red ginseng marc with fermented red koji (RGMK), and to investigate ammonia (NH₃) fluxes from duck litter treated with alum or aluminum chloride (AlCl₃). A total of 270 1-d-old ducks (180 males and 90 females) were allotted in a completely randomized design with 6 treatments and 3 replicates of 15 birds per pen. The six diet treatments were: basal diet, pelleted 1% ST byproduct powder, pelleted 1% RGMK, 1% blends (a mixture of ST byproduct and RGMK) powder, 1% pelleted blends, and coated pellets of 1% blends. The six litter treatments with 6 diet treatments were: no treatment, 50, 100, or 200 g alum/kg duck litter, and 100 g or 200 g AlCl3/kg duck litter (treatments T1, T2, T3, T4, and T5, respectively). During days 10 to 40, ducks fed the 5 experimental diets had significantly different (p<0.05) weight gains and feed conversion ratios compared with those fed the control diet, but initial body weight, final body weight, feed intake, and mortality were not affected. There were significant differences (p<0.05) in NH₃ fluxes among treatments over the 6 weeks of the study, except for week 0. The relative NH₃ losses at week 6 were lower by 25.6, 45.3, 45.6, 46.7, and 48.6% than those in the controls in T1, T2, T3, T4, and T5 respectively. In conclusion, feeding pellets or coated pellets of ST and RGMK and using alum or AlCl₃ in the litter at the same time improves weight gain and feed conversion ratio performance and reduces mortality and NH₃ losses in ducks.

Adjuvant pretreatment with alum protects neonatal mice in sepsis through myeloid cell activation

The high mortality in neonatal sepsis has been related to both quantitative and qualitative differences in host protective immunity. Pretreatment strategies to prevent sepsis have received inadequate consideration, especially in the premature neonate, where outcomes from sepsis are so dismal. Aluminium salts-based adjuvants (alum) are used currently in many paediatric vaccines, but their use as an innate immune stimulant alone has not been well studied. We asked whether pretreatment with alum adjuvant alone could improve outcome and host innate immunity in neonatal mice given polymicrobial sepsis. Subcutaneous alum pretreatment improves survival to polymicrobial sepsis in both wild-type and T and B cell-deficient neonatal mice, but not in caspase-1/11 null mice. Moreover, alum increases peritoneal macrophage and neutrophil phagocytosis, and decreases bacterial colonization in the peritoneum. Bone marrow-derived neutrophils from alum-pretreated neonates produce more neutrophil extracellular traps (NETs) and exhibit increased expression of neutrophil elastase (NE) after in-vitro stimulation with phorbol esters. In addition, alum pretreatment increases bone marrow and splenic haematopoietic stem cell expansion following sepsis. Pretreatment of neonatal mice with an alum-based adjuvant can stimulate multiple innate immune cell functions and improve survival. These novel findings suggest a therapeutic pathway for the use of existing alum-based adjuvants for preventing sepsis in premature infants.

Alum Activates the Bovine NLRP3 Inflammasome

There has been a move away from vaccines composed of whole or inactivated antigens toward subunit-based vaccines, which although safe, provide less immunological protection. As a result, the use of adjuvants to enhance and direct adaptive immune responses has become the focus of much targeted bovine vaccine research. However, the mechanisms by which adjuvants work to enhance immunological protection in many cases remains unclear, although this knowledge is critical to the rational design of effective next generation vaccines. This study aimed to investigate the mechanisms by which alum, a commonly used adjuvant in bovine vaccines, enhances IL-1β secretion in bovine peripheral blood mononuclear cells (PBMCs). Unlike the case with human PBMCs, alum promoted IL-1β secretion in a subset of bovine PBMCs without priming with a toll-like receptor agonist. This suggests that PBMCs from some cattle are primed to produce this potent inflammatory cytokine and western blotting confirmed the presence of preexisting pro-IL-1β in PBMCs from a subset of 8-month-old cattle. To address the mechanism underlying alum-induced IL-1β secretion, specific inhibitors identified that alum mediates lysosomal disruption which subsequently activates the assembly of an NLRP3, ASC, caspase-1, and potentially caspase-8 containing complex. These components form an inflammasome, which mediates alum-induced IL-1β secretion in bovine PBMCs. Given the demonstrated role of the NLRP3 inflammasome in regulating adaptive immunity in murine systems, these results will inform further targeted research into the potential of inflammasome activation for rational vaccine design in cattle.

Type III hypersensitivity reactions to a B cell epitope antigen are abrogated using a depot forming vaccine platform

Peptide antigens are combined with an adjuvant in order to increase immunogenicity in vivo. The immunogenicity and safety of a RSV vaccine formulated in a novel oil-based platform, DepoVax™ (DPX), was compared to an alum formulation. A peptide B cell epitope derived from RSV small hydrophobic ectodomain (SHe) served as the antigen. Both vaccines induced SHe-specific antibodies after immunization of mice. A single dose of the DPX-based formulation resulted in anti-SHe titres for up to 20 weeks. Boosting with Alum-SHe, but not with DPX-SHe, led to unexpected clinical signs such as decreased activity, cyanosis and drop in body temperature in mice but not in rabbits. The severity of adverse reactions correlated with magnitude of SHe-specific IgG immune responses and decreased complement component 3 plasma levels, indicating a type III hypersensitivity reaction. By RP-HPLC analysis, we found that only 8-20% of the antigen was found to be adsorbed to alum in vitro, indicating that this antigen is likely released systemically upon injection in vivo. Clinical signs were not observed in rabbits, indicating the response correlates with peptide dose relative to size of animal. These results suggest that peptide antigens targeted to produce B cell mediated response may result in increased incidence of type III hypersensitivity reactions when delivered in non-depot forming vaccines. The DPX formulation induced strong antibody titres to the antigen without causing adverse events, likely due to the strength of the depot in vivo, and demonstrates the potential safety and immunogenicity of this platform for B cell peptide antigens.

Evaluation of G2 Citric Acid-Based Dendrimer as an Adjuvant in Veterinary Rabies Vaccine

For induction of an appropriate immune response, especially in the case of an inactivated vaccine, the use of an adjuvant is crucial. In this study, adjuvanticity effect of G2 dendrimer in veterinary rabies vaccine has been investigated. A nonlinear globular G2 dendrimer comprising citric acid and polyethylene glycol 600 (PEG-600) was synthesized and the toxicity was studied in vitro on the J774A.1 cell line. The adjuvanticity effect of the dendrimer was then investigated on rabies virus in NMRI mice as a model. Different concentrations of dendrimer were used to determine the best formulation for the survival of the mice after virus challenge. The rise of neutralizing antibody was also checked by rapid fluorescent focus inhibition test (RFFIT). The relative potency of the prepared formulation was finally calculated using standard NIH test and the results were compared (and discussed) with the commercially available rabies vaccine. The accuracy of dendrimer synthesis was confirmed using Fourier transform infrared (FT-IR), size, and zeta potential analysis. The in vitro toxicity assay revealed that no significant toxic effect is observed in cells when data are compared with the control group. The in vivo assay showed that a higher survival rate in the mice received a special formulation due to adjuvanticity effect of dendrimer, which is also confirmed by RFFIT. However, the relative potency of that formulation does not give expected results when compared with the alum-containing rabies vaccine. In the current investigation, the adjuvanticity effect of G2 dendrimer was demonstrated for the first time in rising of neutralizing antibodies against rabies virus. Our data confirm that nanoparticles can enhance immune responses in an appropriate manner. Moreover, engineered nanoparticles will enable us to develop novel potent multivalent adjuvants in vaccine technology.

Recombinant TgHSP70 Immunization Protects against Toxoplasma gondii Brain Cyst Formation by Enhancing Inducible Nitric Oxide Expression

Toxoplasma gondii is known to cause congenital infection in humans and animals and severe disease in immunocompromised individuals; consequently development of vaccines against the parasite is highly necessary. Under stress conditions, T. gondii expresses the highly immunogenic heat shock protein 70 (TgHSP70). Here, we assessed the protective efficacy of rTgHSP70 immunization combined with Alum in oral ME-49 T. gondii infection and the mechanisms involved on it. It was observed that immunized mice with rTgHSP70 or rTgHSP70 adsorbed in Alum presented a significantly reduced number of cysts in the brain that was associated with increased iNOS+ cell numbers in the organ, irrespective the use of the adjuvant. Indeed, ex vivo experiments showed that peritoneal macrophages pre-stimulated with rTgHSP70 presented increased NO production and enhanced parasite killing, and the protein was able to directly stimulate B cells toward antibody producing profile. In addition, rTgHSP70 immunization leads to high specific antibody titters systemically and a mixed IgG1/IgG2a response, with predominance of IgG1 production. Nonetheless, it was observed that the pretreatment of the parasite with rTgHSP70 immune sera was not able to control T. gondii internalization and replication by NIH fibroblast neither peritoneal murine macrophages, nor anti-rTgHSP70 antibodies were able to kill T. gondii by complement-mediated lysis, suggesting that these mechanisms are not crucial to resistance. Interestingly, when in combination with Alum, rTgHSP70 immunization was able to reduce inflammation in the brain of infected mice and in parallel anti-rTgHSP70 immune complexes in the serum. In conclusion, immunization with rTgHSP70 induces massive amounts of iNOS expression and reduced brain parasitism, suggesting that iNOS expression and consequently NO production in the brain is a protective mechanism induced by TgHSP70 immunization, therefore rTgHSP70 can be a good candidate for vaccine development against toxoplasmosis.

Porcine Dendritic Cells as an In Vitro Model to Assess the Immunological Behaviour of Streptococcus suis Subunit Vaccine Formulations and the Polarizing Effect of Adjuvants

An in vitro porcine bone marrow-derived dendritic cell (DC) culture was developed as a model for evaluating immune polarization induced by adjuvants when administered with immunogens that may become vaccine candidates if appropriately formulated. The swine pathogen Streptococcus suis was chosen as a prototype to evaluate proposed S. suis vaccine candidates in combination with the adjuvants Poly I:C, Quil A ®, Alhydrogel ®, TiterMax Gold ® and Stimune ®. The toll-like receptor ligand Poly I:C and the saponin Quil A ® polarized swine DC cytokines towards a type 1 phenotype, with preferential production of IL-12 and TNF-α. The water-in-oil adjuvants TiterMax Gold ® and Stimune ® favoured a type 2 profile as suggested by a marked IL-6 release. In contrast, Alhydrogel ® induced a type 1/type 2 mixed cytokine profile. The antigen type differently modified the magnitude of the adjuvant effect, but overall polarization was preserved. This is the first comparative report on swine DC immune activation by different adjuvants. Although further swine immunization studies would be required to better characterize the induced responses, the herein proposed in vitro model is a promising approach that helps assessing behaviour of the vaccine formulation rapidly at the pre-screening stage and will certainly reduce numbers of animals used while advancing vaccinology science.