Effect of endotoxin and alum adjuvant vaccine on peanut allergy

Murine model of cross-IgE sensitization and cross-anaphylactic reactions among multiple group food allergens

Rationale

Approximately 32 million people in the United States suffer from food allergies. Some food groups, such as legumes - peanuts, tree nuts, fish, and shellfish, have a high risk of cross-reactivity. However, the murine model of multiple food group cross-reactivity is limited.

Objective

We sought to develop a murine model that can be used to investigate novel therapeutics for the treatment of multiple food allergies.

Methods

C3H/HeJ mice were sensitized intraperitoneally (i.p.) once a week for three weeks with a mixture of 500µg of protein from peanut, cashew, walnut, shrimp, cod, and 2 mg Alum. The control group consisted of naïve mice. IgE levels against the sensitized allergens and their cross-reactive allergens were measured by ELISA at baseline and 3 weeks after sensitization. In weeks 4 and 5, the mice were given intragastric challenges with 200mg/mouse of each food: peanut, chickpea, lentil, cashew, almond, pistachio, hazelnut, brazil nut, walnut, pecan, shrimp, lobster, cod, salmon, and mackerel. After each challenge, anaphylactic symptoms, rectal temperatures, and plasma histamine were measured.

Results

There was a significant elevation of IgE against sensitized antigens (peanut cashew, walnut, shrimp, and cod) as well as cross-reactive allergens used for oral food challenge from legumes including peanut, chickpea, and lentil, as well as tree nuts such as cashew, almond, pistachio, hazelnut, brazil nut, walnut, and pecan. Furthermore, there was a significant increase in crustaceans such as shrimp, lobster and fish like cod, salmon, and mackerel (p<0.01). Consistently, significantly increased anaphylactic symptom scores (p<0.05), decreased rectal temperature (p<0.001), and increased plasma histamine (p<0.05) compared to the naïve mice occurred following each challenge with sensitized foods and unsensitized, but cross-reactive foods.

Conclusion

We generated a comprehensive murine model of IgE-mediated multiple food groups of cross-reactive anaphylaxes. This will provide an essential tool for developing novel therapies for cross-reactivity multiple food allergies.

Vaccines and allergic reactions: The past, the current COVID-19 pandemic, and future perspectives

Vaccines are essential public health tools with a favorable safety profile and prophylactic effectiveness that have historically played significant roles in reducing infectious disease burden in populations, when the majority of individuals are vaccinated. The COVID-19 vaccines are expected to have similar positive impacts on health across the globe. While serious allergic reactions to vaccines are rare, their underlying mechanisms and implications for clinical management should be considered to provide individuals with the safest care possible. In this review, we provide an overview of different types of allergic adverse reactions that can potentially occur after vaccination and individual vaccine components capable of causing the allergic adverse reactions. We present the incidence of allergic adverse reactions during clinical studies and through post-authorization and post-marketing surveillance and provide plausible causes of these reactions based on potential allergenic components present in several common vaccines. Additionally, we review implications for individual diagnosis and management and vaccine manufacturing overall. Finally, we suggest areas for future research.

Carbohydrate-based adjuvants

Carbohydrate adjuvants are safe and biocompatible compounds usable as sustained delivery systems and stimulants of ongoing humoral and cellular immune responses, being especially suitable for the development of vaccines against intracellular pathogens where alum is useless. The development of new adjuvants is difficult and expensive, however, in the last two years, seven new carbohydrate-based adjuvants have been patented, also there are twelve ongoing clinical trials of vaccines that contain carbohydrate-based adjuvants, as well as numerous publications on their mechanism of action and safety. More research is necessary to improve the existent adjuvants and develop innovative ones.

Genetically engineered fusion of allergen and viral-like particle induces a more effective allergen-specific immune response than a combination of them

Chimeric virus-like particles (VLPs) were developed as a candidate for allergen-specific immunotherapy. In this study, hepatitis B core antigen (HBcAg) that genetically fused to Chenopodium album polcalcin (Che a 3)-derived peptide was expressed in E. coli BL21, purified, and VLP formation was evaluated using native agarose gel electrophoresis (NAGE) and transmission electron microscopy (TEM). Chimeric HBc VLPs were characterized in terms of their reactivity to IgE, the induction of blocking IgG and allergen-specific IgE, basophil-activating capacity, and Th1-type immune responses. Results from IgE reactivity and basophil activation test showed that chimeric HBc VLPs lack IgE-binding capacity and basophil degranulation activity. Although chimeric HBc VLPs induced the highest level of efficient polcalcin-specific IgG antibody in comparison to those induced by recombinant Che a 3 (rChe a 3) mixed either with HBc VLPs or alum, they triggered the lowest level of polcalcin-specific IgE in mice following immunization. Furthermore, in comparison to the other antigens, chimeric HBc VLPs produced a polcalcin-specific Th1 cell response. Taken together, genetically fusion of allergen derivatives to HBc VLPs, in comparison to a mix of them, may be a more effective way to induce appropriate immune responses in allergen-specific immunotherapy. KEY POINTS: • The insertion of allergen-derived peptide into major insertion region (MIR) of hepatitis B virus core (HBc) antigen resulted in nanoparticles displaying allergen-derived peptide upon its expression in prokaryotic host. • The resultant VLPs (chimeric HBc VLPs) did not exhibit IgE reactivity with allergic patients' sera and were not able to degranulate basophils. • Chimeric HBc VLPs dramatically improved protective IgG antibody response compared with those induced by allergen mixed either with HBc VLPs or alum. • Chimeric HBc VLPs induced Th1 responses that were counterparts of Th2 responses (allergic). • Chimeric HBc VLPs increased IgG2a/ IgG1 ratio and the level of IFN-γ compared to those induced by allergen mixed with either HBc VLPs or alum. Graphical Abstract.

Inhibition of Bcl2L12 Attenuates Eosinophilia-Related Inflammation in the Heart

Background: The eosinophilic inflammation plays a critical role in myocarditis (Mcd); its underlying mechanism remains to be further elucidated. This study aims to investigate the role of Bcl2-like protein 12 (Bcl2L12) in inducing the defects of apoptosis in eosinophils (Eos) of the heart tissues. Methods: Human explant heart samples were collected. Eosinophilia and myocarditis (Mcd)-like inflammation were induced in the mouse heart by immunizing with murine cardiac α-myosin heavy chain (MyHCα) peptides. Results: Markedly more Eos were observed in heart tissues from patients with Mcd than those from patients with dilated cardiomyopathy. Eos isolated from Mcd hearts showed the signs of apoptosis defects. The Eo counts in the Mcd heart tissues were positively correlated with the Bcl2L12 expression in Eos isolated from the heart tissues. Exposure to interleukin 5 in the culture induced the expression of Bcl2L12 in Eos. Bcl2L12 bound c-Myc, the transcription factor of Fas ligand (FasL), to prevent c-Myc from binding to the FasL promoter, to restrict the FasL gene transcription in Eos. Inhibition of Bcl2L12 prevented the induction of eosinophilia and Mcd-like inflammation in the mouse heart. Conclusions: The Bcl2L12 expression contributes to apoptosis defects in Eos of the Mcd heart. Blocking Bcl2L12 prevents the eosinophilia induction and alleviates Mcd-like inflammation in mice.

The External Exposome and Food Allergy

PURPOSE OF REVIEW

The recent increase in childhood food allergy prevalence strongly suggests that environmental exposures are contributing to food allergy development. This review summarizes current knowledge about the role of the external exposome in food allergy.

RECENT FINDINGS

There is growing evidence that environmental exposure to food antigens in house dust through non-oral routes contributes to food sensitization and allergy. Co-exposure to environmental adjuvants in house dust, such as microbial products and fungal allergens, may also facilitate allergic sensitization. While a high-microbe environment is associated with decreased atopy, studies are mixed on whether endotoxin exposure protects against food sensitization. Several chemicals and air pollutants have been associated with food sensitization, but their role in food allergy remains understudied. Children are exposed to numerous environmental agents that can influence food allergy risk. Further studies are needed to identify the key early-life exposures that promote or inhibit food allergy development.