Involvement of poly (γ-glutamic acid) as an allergen in late-onset anaphylaxis due to fermented soybeans (natto)

Emerging and Novel Elicitors of Anaphylaxis: Collegium Internationale Allergologicum Update 2024

BACKGROUND

Anaphylaxis represents the most severe end of the spectrum of allergic reactions. Frequent elicitors of anaphylaxis are insects, foods, and drugs. This paper summarizes recent development with regard to emerging and novel elicitors of anaphylaxis.

SUMMARY

Food allergens on the rise include pulses (like pea, chickpea), seeds (hemp, chia), nuts (cashew), pseudograins (buckwheat, quinoa), fruits, and microalgae. Novel foods are foods that were not consumed to any significant extent in the European Union before May 1997, which includes four edible insects (mealworm, migratory locust, house cricket, and buffalo worm). Recent investigations have pointed out the risk of anaphylaxis associated with the consumption of yellow mealworm for people allergic to shellfish and house dust mites. In Europe, fire ants (mostly Solenopsis invicta) and Vespa velutina nigrithorax represent invasive species, which account for increasing numbers of anaphylactic reactions. Also, several new drugs, especially biologicals, have been associated with anaphylaxis.

KEY MESSAGES

Elicitors of anaphylaxis are changing as a result of (i) increase in demand for plant-based food, (ii) introduction of novel foods, (iii) spreading of allergens by climate changes and globalization, or (iv) due to exposure to newly developed drugs.

Scallop aquaculture has a potential risk of natto-induced hypersensitivity reactions in a local area of northern Japan

BACKGROUND

Fermented soybean (natto)-induced hypersensitivity reactions (natto allergy) are rare and can result in late-onset anaphylaxis. The allergen in natto is considered to be poly-γ-glutamic acid (PGA), and marine sports are a risk factor for natto allergy due to epicutaneous sensitization to PGA from cnidarian stings. However, no research on natto allergy in fishery workers has yet been performed.

METHODS

We conducted a chart review of inpatients diagnosed with anaphylaxis due to natto at Hokkaido Prefectural Haboro Hospital between April 1, 2009, and August 31, 2020. We also administered self-report questionnaires about food hypersensitivity reactions to Japanese fishery workers, including members of the Kitarumoi Fishery Cooperative Association and part-time workers in this area, from February 1 to May 31, 2021.

RESULTS

We found six inpatients (29 inpatients with food-induced anaphylaxis among approximately 11,000 community-dwelling residents) with late-onset anaphylaxis due to natto; all were involved in scallop aquaculture. The questionnaires revealed that 27 participants had natto allergy. We divided the fishery workers into a scallop aquaculture (Scallop) group (n = 211) and other fishery group (n = 106). The Scallop group was significantly associated with natto allergy after adjustments for confounders (OR: 5.73, 95% CI: 1.46-22.56) by logistic regression analysis. In the Scallop group, older age, experience in repairing nets, and a longer length of work experience were significantly related to participants with natto allergy (n = 23), but not participants without natto allergy (n = 181).

CONCLUSIONS

Our results indicated an association between scallop aquaculture and natto allergy.

Nattokinase, a subtilisin family serine protease, is a novel allergen contained in the traditional Japanese fermented food natto

BACKGROUND

Immediate allergy caused by natto, a popular Japanese food prepared by fermenting soybeans with Bacillus subtilis var. natto, has been reported. Polygamma glutamic acid (PGA) in the sticky substance around natto beans has been reported to be a causative allergen of natto allergy. However, some of our patients with natto allergy were negative for PGA in the skin prick test (SPT). The sticky substance of natto beans contains a subtilisin family serine protease, nattokinase, along with PGA. In this study, we aimed to examine the antigenicity of nattokinase in natto allergy.

METHODS

Eight patients, who developed symptoms after ingesting natto and positively reacted to natto (seven to the sticky substance in natto and one to the whole natto product) in their SPT, were enrolled in this study. To analyze IgE reactivity, we performed immunoblotting, ELISA, and SPT for natto (bean and sticky substance), and/or PGA, and/or nattokinase and/or cultured B. subtilis var. natto extract.

RESULTS

In the SPT, four cases each were PGA-positive and PGA-negative. Immunoblotting of the sera from PGA-negative patients showed a protein band at 30 kDa, which was identified as nattokinase. Three PGA-negative cases, but not three PGA-positive cases, showed a positive reaction to nattokinase in the SPT and had a history of atopic dermatitis. The ELISA for nattokinase revealed a positive reaction of PGA-negative cases and negative reaction of PGA-positive cases in the SPT.

CONCLUSIONS

We identified a subtilisin family serine protease, nattokinase, as a novel allergen in natto allergy patients unsensitized to PGA.

Diagnostic utility of the basophil activation test in natto-induced hypersensitivity

BACKGROUND

Natto (fermented soybeans)-induced hypersensitivity is characterized by delayed symptom onset that hampers diagnosis. We aimed to clarify the clinical utility of the basophil activation test (BAT) in the diagnosis of natto-induced hypersensitivity.

METHODS

Five patients with a history of anaphylaxis and chronic urticaria suspected of natto-induced hypersensitivity and seven with chronic spontaneous urticaria clinically unrelated to natto were enrolled in the patient and control groups, respectively. The BAT was performed with two incubation times, 15 min and 1 h, in combination with various concentrations of natto-mucilage extract.

RESULTS

In controls, CD203c levels in basophils remained low in the 15-min incubation but were significantly increased in the 1-h incubation. In the patient group, in the 15-min condition, basophil CD203c was significantly upregulated by natto mucilage but not by soybean vs controls (P = 0.001). Low concentrations of natto mucilage were sufficient to upregulate basophil CD203c in the anaphylaxis cases, but high concentrations were required to induce the same effect in the urticaria cases. Finally, the dose-dependent pattern of the BAT results differed significantly between the anaphylaxis and urticaria cases (P = 0.006). Thus, a strong background reaction was observed in the BAT with 1 h incubation; 15 min of incubation was sufficient to identify patients with natto-induced hypersensitivity and may distinguish the clinical phenotype of natto-induced hypersensitivity, i.e., anaphylaxis or urticaria.

CONCLUSIONS

The BAT with a 15-min incubation period is useful in diagnosing natto-induced hypersensitivity.

To PEGylate or not to PEGylate: Immunological properties of nanomedicine's most popular component, polyethylene glycol and its alternatives

Polyethylene glycol or PEG has a long history of use in medicine. Many conventional formulations utilize PEG as either an active ingredient or an excipient. PEG found its use in biotechnology therapeutics as a tool to slow down drug clearance and shield protein therapeutics from undesirable immunogenicity. Nanotechnology field applies PEG to create stealth drug carriers with prolonged circulation time and decreased recognition and clearance by the mononuclear phagocyte system (MPS). Most nanomedicines approved for clinical use and experimental nanotherapeutics contain PEG. Among the most recent successful examples are two mRNA-based COVID-19 vaccines that are delivered by PEGylated lipid nanoparticles. The breadth of PEG use in a wide variety of over the counter (OTC) medications as well as in drug products and vaccines stimulated research which uncovered that PEG is not as immunologically inert as it was initially expected. Herein, we review the current understanding of PEG's immunological properties and discuss them in the context of synthesis, biodistribution, safety, efficacy, and characterization of PEGylated nanomedicines. We also review the current knowledge about immunological compatibility of other polymers that are being actively investigated as PEG alternatives.

Formulations for Allergen Immunotherapy in Human and Veterinary Patients: New Candidates on the Horizon

Allergen immunotherapy is currently the only causal treatment for allergic diseases in human beings and animals. It aims to re-direct the immune system into a tolerogenic or desensitized state. Requirements include clinical efficacy, safety, and schedules optimizing patient or owner compliance. To achieve these goals, specific allergens can be formulated with adjuvants that prolong tissue deposition and support uptake by antigen presenting cells, and/or provide a beneficial immunomodulatory action. Here, we depict adjuvant formulations being investigated for human and veterinary allergen immunotherapy.

Surfing as a risk factor for sensitization to poly(γ-glutamic acid) in fermented soybeans, natto, allergy

BACKGROUND

Poly(γ-glutamic acid) (PGA) is an allergen in natto, fermented soybeans, which causes late-onset anaphylaxis. We hypothesized that jellyfish stings sensitize adults to PGA because a surfer had allergies to both natto and jellyfish, whose sting contains PGA. The aim of the study was to identify behavioral factors, such as marine sports, associated with PGA sensitization.

METHODS

Outpatients diagnosed with food allergies based on relevant clinical history, positive skin test and/or food challenge test answered a questionnaire during a regular visit in 2016.

RESULTS

Questionnaire data from 140 outpatients were analyzed. These patients were divided into two groups: natto allergy group (13 patients, M:F = 10:3, mean age 40.6 years) and non-natto allergy group (127 patients, M:F = 46:81, mean age 44.5 years). All patients with natto allergy had positive results in skin prick test and basophil activation test with PGA. Of these, 92.3% had a marine sport hobby, especially surfing (84.6%). PGA sensitization was independently associated with marine sports (odds ratio, 278.0, 95 percent confidence interval, 36.9-6315.9, p < 0.001) adjusted for male sex and sea bathing, but not with male sex or sea bathing. In addition, although there was no significant difference in the experience of marine sports between natto and non-natto allergy groups, the natto allergy group participated significantly more frequently in marine sports than the non-natto allergy group (p < 0.001). There was no significant difference between natto consumption amount and PGA sensitization.

CONCLUSIONS

Surfing is a risk factor for PGA sensitization in those with allergy to natto.

Detection of soybean proteins in fermented soybean products by using heating extraction

Soybean is used in processed foods worldwide. Because soybean can cause adverse reactions in some atopic patients, appropriate labeling regarding its content in processed foods is needed to better protect consumers. In the previous study, we developed a reliable sandwich Enzyme Linked Immunosorbent Assay (ELISA) method with high sensitivity and specificity for detecting soybean proteins by using antibody to Gly m Bd 30K, which was originally characterized as a vacuolar protein with a molecular mass of 34 kDa in soybean. The ELISA displayed satisfactory repeatability and reproducibility in an interlaboratory evaluation. However, it could not detect soybean protein in fermented soybean products. We therefore developed an extraction method combined with a heating process to inhibit soybean protein degradation by microbial proteolytic enzymes in fermented soybean products. This extraction method enables the sensitive detection of soybean protein in fermented soybean products such as natto and miso. It was able to detect with high-sensitivity soybean protein present at 10 μg/g levels in model processed foods. This method is suitable for quantifying soybean protein in processed foods without the degrading effects of microbial proteolytic enzymes. The present extraction method can be used sensitively to monitor labeling systems in a reliable manner and should be useful for the mandatory inspections required under Japanese regulations.

PRACTICAL APPLICATION

The extraction and ELISA methods that we developed enable sensitive detection of soybean protein in soybean products, including fermented foods. These methods should be useful for reliable and sensitive monitoring of product labeling systems and should help to solve the problem of insensitive in soybean labeling of processed foods.