Preclinical safety study of a recombinant Streptococcus pyogenes vaccine formulated with aluminum adjuvant

The effect of pomegranate juice supplementation on C-reactive protein levels: GRADE-assessed systematic review and dose-response updated meta-analysis of data from randomized controlled trials

Pomegranate juice (PJ) has a possible anti-inflammatory effect because of its polyphenol content and antioxidants. However, the anti-inflammatory effect of PJ in randomized controlled trials (RCTs) has not been consistent. A previous meta-analysis conducted in 2016 reported a nonsignificant lowering effect of PJ on C-reactive protein (CRP) levels. This systematic review and meta-analysis aim to update the pooled effect size of PJ supplementation on CRP levels in RCT studies. PubMed, Scopus, and Web of Science databases were comprehensively searched until July 2023. Eligible studies were found by screening, their relevant data was extracted, and a risk of bias assessment was performed. The pooled effect size was calculated using a random effect model as the weighted mean difference (WMD) with a 95% confidence interval. This systematic review included 11 studies with 13 effect sizes and 696 participants. Meta-analysis showed that PJ supplementation led to a significant decrease in CRP levels compared to control groups (WMD: -2.55 mg/L; 95%CI: -3.44 to -1.66; p < 0.001). Subgroup analysis demonstrated the significant reduction effect of PJ on CRP levels in studies conducted on the both sexes or only females as well as Iranian population, individuals with 40 years≤, type 2 diabetes, polycystic ovary syndrome, or trials that intervened with PJ dosage of <250 ml/day. Meta-regression and dose-response analysis reported a nonsignificant linear and nonlinear relationship between intervention characteristics (duration and dose of PJ) and CRP changes. The current meta-analysis revealed that PJ supplemantation has a beneficial effect in improving CRP levels. It is recommended to understand this effect better, and find the optimal dose and duration of PJ supplementation to reduce CRP levels in the blood, and repeat meta-analysis after related RCTs are available. For the final proof of these effects, more detailed human studies are needed.

Research opportunities for the primordial prevention of rheumatic fever and rheumatic heart disease-streptococcal vaccine development: a national heart, lung and blood institute workshop report

Streptococcus pyogenes, also known as group A streptococcus (StrepA), is a bacterium that causes a range of human diseases, including pharyngitis, impetigo, invasive infections, and post-infection immune sequelae such as rheumatic fever and rheumatic heart disease. StrepA infections cause some of the highest burden of disease and death in mostly young populations in low-resource settings. Despite decades of effort, there is still no licensed StrepA vaccine, which if developed, could be a cost-effective way to reduce the incidence of disease. Several challenges, including technical and regulatory hurdles, safety concerns and a lack of investment have hindered StrepA vaccine development. Barriers to developing a StrepA vaccine must be overcome in the future by prioritising key areas of research including greater understanding of StrepA immunobiology and autoimmunity risk, better animal models that mimic human disease, expanding the StrepA vaccine pipeline and supporting vaccine clinical trials. The development of a StrepA vaccine is a complex and challenging process that requires significant resources and investment. Given the global burden of StrepA infections and the potential for a vaccine to save lives and livelihoods, StrepA vaccine development is an area of research that deserves considerable support. This report summarises the findings of the Primordial Prevention Working Group-VAX, which was convened in November 2021 by the National Heart, Lung, and Blood Institute. The focus of this report is to identify research gaps within the current StrepA vaccine landscape and find opportunities and develop priorities to promote the rapid and successful advancement of StrepA vaccines.

Group A Streptococcus Vaccine Targeting the Erythrogenic Toxins SpeA and SpeB Is Safe and Immunogenic in Rabbits and Does Not Induce Antibodies Associated with Autoimmunity

Group A streptococcus (GAS) is a global pathogen associated with significant morbidity and mortality for which there is currently no licensed vaccine. Vaccine development has been slow, mostly due to safety concerns regarding streptococcal antigens associated with autoimmunity and related complications. For a GAS vaccine to be safe, it must be ensured that the antigens used in the vaccine do not elicit an antibody response that can cross-react with host tissues. In this study, we evaluated the safety of our GAS vaccine candidate called VaxiStrep in New Zealand White rabbits. VaxiStrep is a recombinant fusion protein comprised of streptococcal pyrogenic exotoxin A (SpeA) and exotoxin B (SpeB), also known as erythrogenic toxins, adsorbed to an aluminum adjuvant. The vaccine elicited a robust immune response against the two toxins in the rabbits without any adverse events or toxicity. No signs of autoimmune pathology were detected in the rabbits' brains, hearts, and kidneys via immunohistochemistry, and serum antibodies did not cross-react with cardiac or neuronal tissue proteins associated with rheumatic heart disease or Sydenham chorea (SC). This study further confirms that VaxiStrep does not elicit autoantibodies and is safe to be tested in a first-in-human trial.

Inflammation and Autophagy: A Convergent Point between Autism Spectrum Disorder (ASD)-Related Genetic and Environmental Factors: Focus on Aluminum Adjuvants

Autism spectrum disorder (ASD), schizophrenia, and bipolar disorder are genetically complex and heterogeneous neurodevelopmental disorders (NDDs) resulting from genetic factors and gene-environment (GxE) interactions for which onset occurs in early brain development. Recent progress highlights the link between ASD and (i) immunogenetics, neurodevelopment, and inflammation, and (ii) impairments of autophagy, a crucial neurodevelopmental process involved in synaptic pruning. Among various environmental factors causing risk for ASD, aluminum (Al)-containing vaccines injected during critical periods have received special attention and triggered relevant scientific questions. The aim of this review is to discuss the current knowledge on the role of early inflammation, immune and autophagy dysfunction in ASD as well as preclinical studies which question Al adjuvant impacts on brain and immune maturation. We highlight the most recent breakthroughs and the lack of epidemiological, pharmacokinetic and pharmacodynamic data constituting a "scientific gap". We propose additional research, such as genetic studies that could contribute to identify populations at genetic risk, improving diagnosis, and potentially the development of new therapeutic tools.

Clearance, biodistribution, and neuromodulatory effects of aluminum-based adjuvants. Systematic review and meta-analysis: what do we learn from animal studies?

Aluminum (Al) salts are commonly used as adjuvants in human and veterinary vaccines for almost a century. Despite this long history of use and the very large number of exposed individuals, data in the literature concerning the fate of these molecules after injection and their potential effects on the nervous system is limited. In the context of (i) an increase of exposure to Al salts through vaccination; (ii) the absence of safety values determined by health regulators; (iii) the lack of robustness of the studies used as references to officially claim Al adjuvant innocuity; (iv) the publication of several animal studies investigating Al salts clearance/biopersistence and neurotoxicity; we have examined in this review all published studies performed on animals and assessing Al adjuvants kinetics, biodistribution, and neuromodulation since the first work of A. Glenny in the 1920s. The diversity of methodological approaches, results, and potential weaknesses of the 31 collected studies are exposed. A large range of protocols has been used, including a variety of exposure schedule and analyses methods, making comparisons between studies uneasy. Nevertheless, published data highlight that when biopersistence, translocation, or neuromodulation were assessed, they were documented whatever the different in vivo models and methods used. Moreover, the studies pointed out the crucial importance of the different Al adjuvant physicochemical properties and host genetic background on their kinetics, biodistribution, and neuromodulatory effects. Regarding the state of the art on this key public health topic, further studies are clearly needed to determine the exact safety level of Al salts.

Streptococcal bacterial components in cancer therapy

The incidence rate of cancer is steadily increasing all around the world, and there is an urgent need to develop novel and more effective treatment strategies. Recently, bacterial therapy has been investigated as a new approach to target cancer, and is becoming a serious option. Streptococcus strains are among the most common and well-studied virulent bacteria that cause a variety of human infections. Everyone has experienced a sore throat during their lifetime, or has been asymptomatically colonized by streptococci. The ability of Streptococcus bacteria to fight cancer was discovered more than 100 years ago, and over the years has undergone clinical trials, but the mechanism is not yet completely understood. Recently, several animal models and human clinical trials have been reported. Streptococcal strains can have an intrinsic anti-tumor activity, or can activate the host immune system to fight the tumor. Bacteria can selectively accumulate and proliferate in the hypoxic regions of solid tumors. Moreover, the bacteria can be genetically engineered to secrete toxins or enzymes that can specifically attack the tumors.

Effects of green coffee bean extract on C-reactive protein levels: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND & OBJECTIVE

The effects of green coffee bean extract (GCBE) supplementation on inflammatory biomarkers have been widely spread. The purpose of this article was to assess the impact of GCBE supplementation on C-reactive protein (CRP) levels.

METHODS

The literature search was performed in four databases (Scopus, PubMed, the Cochrane Library, and Google Scholar) to identify studies that examined the influence of GCBE supplementation on CRP levels up to August 2019. Mean and standard deviation (SD) of the outcomes were used to estimate the weight mean difference (WMD) between intervention and control groups for the follow-up period.

RESULTS

Five (5) studies, with 6 arms, reported CRP as an outcome. Statistically, the use of GCBE supplements resulted in a significant change in CRP levels (WMD: -0.017 mg/dL, 95 % CI: -0.032, -0.003, p = 0.018), whose overall findings were obtained from random-effects model. In addition, a significantly greater reduction in CRP was noted for studies with doses of GCBE supplements ≥ 1000 mg/d (WMD: -0.015 mg/dL, 95 % CI: -0.020, -0.010, p < 0.000), length of intervention < 4 weeks (WMD: -0.015 mg/dL, 95 % CI: -0.020, -0.010, p < 0.001), and for non-healthy subjects (WMD: -0.019 mg/dL, 95 % CI: -0.027, -0.011, p < 0.001). Dyslipidemia, hypertension and non-alcoholic fatty liver disease were the ailments of the studies that encompassed non-healthy patients.

CONCLUSIONS

This meta-analysis shows that the use of GCBE supplements resulted in a statistical decrease in CRP levels, mainly for non-healthy subjects. However, due to the limited number of studies, further randomized clinical trials are crucial in this regard.

Granulomas Following Subcutaneous Injection With Aluminum Adjuvant-Containing Products in Sheep

The use of vaccines including aluminum (Al)–based adjuvants is widespread among small ruminants and other animals. They are associated with the appearance of transient injection site nodules corresponding to granulomas. This study aims to characterize the morphology of these granulomas, to understand the role of the Al adjuvant in their genesis, and to establish the presence of the metal in regional lymph nodes. A total of 84 male neutered lambs were selected and divided into 3 treatment groups of 28 animals each: (1) vaccine (containing Al-based adjuvant), (2) adjuvant-only, and (3) control. A total of 19 subcutaneous injections were performed in a time frame of 15 months. Granulomas and regional lymph nodes were evaluated by clinicopathological means. All of the vaccine and 92.3% of the adjuvant-only lambs presented injection-site granulomas; the granulomas were more numerous in the group administered the vaccine. Bacterial culture in granulomas was always negative. Histologically, granulomas in the vaccine group presented a higher degree of severity. Al was specifically identified by lumogallion staining in granulomas and lymph nodes. Al median content was significantly higher ( P < .001) in the lymph nodes of the vaccine group (82.65 μg/g) compared with both adjuvant-only (2.53 μg/g) and control groups (0.96 μg/g). Scanning transmission electron microscopy demonstrated aggregates of Al within macrophages in vaccine and adjuvant-only groups. In these two groups, Al-based adjuvants induce persistent, sterile, subcutaneous granulomas with macrophage-driven translocation of Al to regional lymph nodes. Local translocation of Al may induce further accumulation in distant tissues and be related to the appearance of systemic signs.

Using vaccine Immunostimulation/Immunodynamic modelling methods to inform vaccine dose decision-making

Unlike drug dose optimisation, mathematical modelling has not been applied to vaccine dose finding. We applied a novel Immunostimulation/Immunodynamic mathematical modelling framework to translate multi-dose TB vaccine immune responses from mice, to predict most immunogenic dose in humans. Data were previously collected on IFN-γ secreting CD4+ T cells over time for novel TB vaccines H56 and H1 adjuvanted with IC31 in mice (1 dose groups (0.1-1.5 and 15 μg H56 + IC31), 45 mice) and humans (1 dose (50 μg H56/H1 + IC31), 18 humans). A two-compartment mathematical model, describing the dynamics of the post-vaccination IFN-γ T cell response, was fitted to mouse and human data, separately, using nonlinear mixed effects methods. We used these fitted models and a vaccine dose allometric scaling assumption, to predict the most immunogenic human dose. Based on the changes in model parameters by mouse H56 + IC31 dose and by varying the H56 dose allometric scaling factor between mouse and humans, we established that, at a late time point (224 days) doses of 0.8-8 μg H56 + IC31 in humans may be the most immunogenic. A 0.8-8 μg of H-series TB vaccines in humans, may be as, or more, immunogenic, as larger doses. The Immunostimulation/Immunodynamic mathematical modelling framework is a novel, and potentially revolutionary tool, to predict most immunogenic vaccine doses, and accelerate vaccine development.

Immunological characteristics of Mycobacterium tuberculosis subunit vaccines immunized through different routes

Tuberculosis is chronic infectious disease caused by Mycobacterium tuberculosis (M.tb) that is prevalent worldwide. Several specific antigens, such as Antigen 85B (Ag85B) and 6 kDa early secretory antigenic target (ESAT-6) protein of M.tb, are listed as some of the candidate subunit vaccines against M.tb. ESAT-6, as a virulent factor and differential gene in M.tb, shows insufficient immunogenicity in animal model. In order to investigate the ways to improve the immunogenicity of ESAT-6, we immunized ESAT-6 by subcutaneous and intramuscular routes with different adjuvants. We found that ESAT-6 immunized alone did not induce significant humoral immunity in both immunization routes. However, subcutaneous immunization of ESAT-6 plus incomplete Freund's adjuvant can induce a significant humoral immune response, enhanced proliferation and elevated secretion of IFN-γ from splenocytes. Intramuscular immunization of ESAT-6 plus adjuvant aluminum salt or poly(I:C) did not enhance humoral and cellular immune responses. Therefore, it is concluded that immunization of ESAT-6 subcutaneously plus incomplete Freund's adjuvant induces stronger humoral and cellular immune responses, which can be considered of ESAT-6 as a subunit vaccine in further research against tuberculosis.

The effect of zinc supplementation on plasma C-reactive protein concentrations: A systematic review and meta-analysis of randomized controlled trials

Previous studies have shown zinc has potential anti-inflammatory and anti-oxidative effects. However, findings from clinical trials about the effect of zinc on plasma C-reactive protein (CRP) appeared inconsistent and uncertain. Therefore, the aim of this meta-analysis was to summarize the effect of zinc supplementation on plasma CRP concentrations in adults. The literature search through PubMed, SCOPUS, and Google Scholar were done to find published studies up to October 2017. Random or fixed-effects model depending on the results of heterogeneity tests were used to estimate the pooled effect size. Between-study heterogeneity was assessed using Cochran's Q test and I2 index. Funnel plot and Egger's regression test were used to assess publication bias. Our search found 1505 publications, of which 8 randomized controlled trials (RCTs) were eligible to be included in the analysis. The results of the meta-analysis displayed a significant reduction in circulating CRP levels (WMD: - 1.68 mg/l; 95% CI: - 2.4 to - 0.9, P = <0.001) following zinc supplementation. In the subgroup analysis, supplementation dosage, study quality, study population, and baseline CRP level were the potential sources of heterogeneity. Participants took equal to 50 mg/d zinc (WMD: - 1.97 mg/l; 95% CI: - 2.28 to - 1.67, P = <0.001), low quality studies (WMD: - 2.9 mg/l; 95% CI: - 3.68 to - 2.12, P = <0.001) and those with renal dysfunction (WMD: - 7.43 mg/l; 95% CI: - 12.57 to -2.29, P = 0.005) showed greater improvement in CRP levels. In conclusion, zinc supplementation may have a beneficial effect on the serum CRP, especially at doses equal to 50 mg/d and in renal insufficiency patients compared with healthy subjects.

Polymer-Based Nanomaterials and Applications for Vaccines and Drugs

Nanotechnology plays a significant role in drug development. As carriers, polymeric nanoparticles can deliver vaccine antigens, proteins, and drugs to the desired site of action. Polymeric nanoparticles with lower cytotoxicity can protect the delivered antigens or drugs from degradation under unfavorable conditions via a mucosal administration route; further, the uptake of nanoparticles by antigen-presenting cells can increase and induce potent immune responses. Additionally, nanomaterials are widely used in vaccine delivery systems because nanomaterials can make the vaccine antigen long-acting. This review focuses on some biodegradable polymer materials such as natural polymeric nanomaterials, chemically synthesized polymer materials, and biosynthesized polymeric materials, and points out the advantages and the direction of research on degradable polymeric materials. The application and future perspectives of polymeric materials as delivery carriers and vaccine adjuvants in the field of drugs and vaccines are presented. With the increase of knowledge and fundamental understandings of polymer-based nanomaterials, means of integrating some other attractive properties, such as slow release, target delivery, and alternative administration methods and delivery pathways are feasible. Polymer-based nanomaterials have great potential for the development of novel vaccines and drug systems for certain needs, including single-dose and needle-free deliveries of vaccine antigens and drugs in the future.