Cloning and expression of a biologically active Anisakis simplex allergen Ani s 1 in the yeast Pichia pastoris

Evaluating Potential Risks of Food Allergy and Toxicity of Soy Leghemoglobin Expressed in Pichia pastoris

SCOPE

The Soybean (Glycine max) leghemoglobin c2 (LegHb) gene was introduced into Pichia pastoris yeast for sustainable production of a heme-carrying protein, for organoleptic use in plant-based meat. The potential allergenicity and toxicity of LegHb and 17 Pichia host-proteins each representing ≥1% of total protein in production batches are evaluated by literature review, bioinformatics sequence comparisons to known allergens or toxins, and in vitro pepsin digestion.

METHODS AND RESULTS

Literature searches found no evidence of allergenicity or toxicity for these proteins. There are no significant sequence matches of LegHb to known allergens or toxins. Eleven Pichia proteins have modest identity matches to minor environmental allergens and 13 Pichia proteins have significant matches to proteins from toxic sources. Yet the matched allergens and toxins have similar matches to proteins from the commonly consumed yeast Saccharomyces cerevisiae, without evidence of food allergy or toxicity. The demonstrated history of safe use indicates additional tests for allergenicity and toxicity are not needed. The LegHb and Pichia sp. proteins were rapidly digested by pepsin at pH 2.

CONCLUSION

These results demonstrate that foods containing recombinant soy LegHb produced in Pichia sp. are unlikely to present an unacceptable risk of allergenicity or toxicity to consumers.

Allergenicity of bony and cartilaginous fish - molecular and immunological properties

Allergy to bony fish is common and probably increasing world-wide. The major heat-stable pan-fish allergen, parvalbumin (PV), has been identified and characterized for numerous fish species. In contrast, there are very few reports of allergic reactions to cartilaginous fish despite widespread consumption. The molecular basis for this seemingly low clinical cross-reactivity between these two fish groups has not been elucidated. PV consists of two distinct protein lineages, α and β. The α-lineage of this protein is predominant in muscle tissue of cartilaginous fish (Chondrichthyes), while β-PV is abundant in muscle tissue of bony fish (Osteichthyes). The low incidence of allergic reactions to ingested rays and sharks is likely due to the lack of molecular similarity, resulting in reduced immunological cross-reactivity between the two PV lineages. Structurally and physiologically, both protein lineages are very similar; however, the amino acid homology is very low with 47-54%. Furthermore, PV from ancient fish species such as the coelacanth demonstrates 62% sequence homology to leopard shark α-PV and 70% to carp β-PV. This indicates the extent of conservation of the PV isoforms lineages across millennia. This review highlights prevalence data on fish allergy and sensitization to fish, and details the molecular diversity of the two protein lineages of the major fish allergen PV among different fish groups, emphasizing the immunological and clinical differences in allergenicity.

Previous Exposure to the Fish Parasite Anisakis as a Potential Risk Factor for Gastric or Colon Adenocarcinoma

Anisakiasis is a global disease caused by consumption of raw or lightly cooked fish contaminated with L3 Anisakis spp. larvae. High rates of parasitization of fish worldwide make Anisakis a serious health hazard. In fact, anisakiasis is a growing disease in countries such as Spain, Italy, and Japan, where consumption of raw/marinated fish is high. Some parasitic infections have been recognized as a causative factor for human cancer. Suggested mechanisms include chronic inflammation elicited by the parasite, and a possible tumorigenic effect from certain parasitic secretions. Anisakis can produce persistent local inflammation and granuloma, and larvae have been incidentally found in gastrointestinal (GI) tumors. Our aim was to discover possible differences in the prevalence of unnoticed or asymptomatic previous Anisakis infection in GI cancer patients compared with healthy individuals. Serum levels of specific antibodies against Anisakis antigens were used as a reliable marker of previous contact with their larvae. Ninety-four participants without a previous history of Anisakis infection were prospectively allocated into 1 of 2 groups: 47 patients with GI cancer and 47 controls. Specific IgE, IgA1, and IgG1 against the Anisakis recombinant antigens Ani s 1, Ani s 5, Ani s 9, and Ani s 10 were determined by an ELISA assay. The ratio of positivity to sIgA1, rAni s 1, or rAni s 5 was significantly higher in the cancer patients than in the controls (38.30% vs 6.38%, P < 0.001) and (42.55% vs 10.64%, P < 0.001, respectively). When disaggregated by type of tumor, the patients with gastric cancer showed a higher proportion of positive results for sIgA1 to rAni s 1 (P < 0.001), whereas a higher proportion of colon cancer patients were shown to be positive for sIgA1 to both rAni s 1 (P < 0.05) and rAni s 5 (P < 0.01). Earlier Anisakis infection might be a risk factor for the development of stomach or colon cancer.

Allergenicity of two Anisakis simplex allergens evaluated in vivo using an experimental mouse model

Anisakis (Anisakidae) is one of the most important causes of helminth-induced allergic reactions and elicits clinical responses that include urticaria, rhinitis, bronco-constriction, cough, and/or gastrointestinal symptoms. More than 13 reactive allergens have been identified in the serum of Anisakis allergy patients, but the allergenicity of only a few of these have been evaluated in vivo using a mouse model. To evaluate the allergenicity of two important allergens, Ani s 1 and Ani s 9, we induced experimental allergic airway inflammation in a mouse model by repeated intranasal administration of the allergens. Both recombinant proteins (rAni s 1 and rAni s 9) elicited increased airway hyperresponsivity, airway infiltration by inflammatory cells (especially eosinophils), bronchial epithelial cell hyperplasia, all of which are characteristic of allergic airway inflammation. These allergens significantly increased the levels of Th2-related cytokines (IL-4, IL-5, IL-13, and IL-25) and Th17 related cytokines (IL-6 and IL-17) in both splenocytes and airway (except IL-17 in airway by rAni s 9). OVA-specific IgE and total IgE were increased in rAni s 1 and rAni s 9 treated mice as compared with controls treated with OVA alone. In addition, these two allergens induced gene expression of thymic stromal lymphopoietin (TSLP) and IL-25 (initiators of the Th2 response), as well as CXCL1 (initiator of the Th17 response) in mouse lung epithelial cells. In conclusion, repeated intranasal treatments with rAni s 1 and rAni s 9 induced airway inflammation in mice by elevating of Th2 and Th17 responses in the lung.

Cross-reactivity between Anisakis spp. and wasp venom allergens

BACKGROUND

Anisakiasis is caused by the consumption of raw or undercooked fish or cephalopods parasitized by live L3 larvae of nematode Anisakis spp. Larvae anchor to stomach mucosa releasing excretion/secretion products which contain the main allergens. It has been described that nematode larvae release venom allergen-like proteins among their excretion/secretion products. We investigated potential cross-reactivity between Anisakis and wasp venom allergens.

METHODS

Two groups of 25 patients each were studied: wasp venom- and Anisakis-allergic patients. Sera from patients were tested by ImmunoCAP, dot-blotting with recombinant Anisakis allergens and ADVIA-Centaur system with Hymenoptera allergens. Cross-reactivity was assessed by IgE immunoblotting inhibition assays. Role of cross-reactive carbohydrate determinants (CCDs) was studied by inhibition with bromelain and periodate treatment.

RESULTS

A total of 40% of wasp venom-allergic patients had specific IgE to Anisakis simplex and 20% detected at least one of the Anisakis recombinant allergens tested. Likewise, 44% of Anisakis-allergic patients had specific IgE to Vespula spp. venom and 16% detected at least one of the Hymenoptera allergens tested. Wasp venom-allergic patients detected CCDs in Anisakis extract and peptide epitopes on Anisakis allergens rAni s 1 and rAni s 9, whereas Anisakis-allergic patients only detected CCDs on nVes v 1 allergen from Vespula spp. venom. The only Anisakis allergen inhibited by Vespula venom was rAni s 9.

CONCLUSIONS

This is the first time that cross-sensitization between wasp venom and Anisakis is described. CCDs are involved in both cases; however, peptide epitopes are only recognized by wasp venom-allergic patients.

Anisakis allergy component-resolved diagnosis: clinical and immunologic differences between patients from Italy and Spain

BACKGROUND

Anisakissimplex is the main organism responsible for the zoonotic disease anisakiasis which follows the ingestion of live larvae present in raw or undercooked marine fish. Clinical features include severe epigastric pain, frequently accompanied by severe allergic reactions. We investigated the prevalence of immunoglobulin E (IgE) specific for 5 Anisakis allergens in Italian patients sensitized or allergic to the parasite. The results were compared with those obtained previously in a similar Spanish population.

PATIENTS AND METHODS

We conducted a descriptive, cross-sectional validation study. Asymptomatic Anisakis-sensitized subjects (15 Italian and 17 Spanish) and Anisakis allergic-patients (42 Italian and 35 Spanish) were studied by ImmunoCAP, Western-blotting with nAni s 4 and dot-blotting with rAni s 1, rAni s 5, rAni s 9 and rAni s 10.

RESULTS

Anisakis IgE CAP classes 1 or 2 were associated with a high probability of asymptomatic sensitization (66.7%) while CAP classes 4 or above, were associated with a very high probability of allergy to Anisakis (95.2%). The most frequently detected allergen among Italian and Spanish allergic patients was Ani s 1. All of the Spanish patients versus 76.2% of the Italian patients recognized at least one of the allergens tested. Patients suffering from gastrointestinal symptoms only were significantly more frequent among the Italians whereas the Spanish presented more frequently with urticaria, angioedema or anaphylaxis.

CONCLUSIONS

Anisakis hypersensitivity shows different immunological patterns in different European countries. Allergen component diagnosis might help us to better understand this complex entity. Anisakis-specific IgE levels may have moderate prognostic significance.

Elucidation of IgE-binding epitopes of Ani s 1: the major Anisakis simplex allergen

Ani s 1, the major allergen of Anisakis simplex, is expected to be a useful antigen in allergen-specific immunotherapy of Anisakis allergy. To avoid side-effects such as anaphylactic shock in immunotherapy, it is desirable to use not native allergens but hypoallergenic mutants devoid of IgE-binding epitopes. This study was hence aimed to elucidate IgE-binding epitopes of Ani s 1 toward the development of hypoallergenic Ani s 1 mutants. Mapping experiments using 32 peptides (P1-32) revealed that major IgE-binding epitopes are included in P24 (region 116-130) and P28 (region 136-150). Furthermore, Ala-scanning and truncation experiments established that eight (underlined in the sequence 116-ELFAREYEGVCKSGK-130) and nine amino acid residues (underlined in the sequence 136-RGSGWMMTILGKSCD-150) are crucial for the IgE-binding of P24 and P28, respectively. The determined crucial residues of P24 and P28 were assumed to be involved in electrostatic and hydrophobic interactions with IgE, respectively.

New insights into seafood allergy

PURPOSE OF REVIEW

Seafood plays an important role in human nutrition worldwide, sustained by international trade of a variety of new seafood products. Increased production and consumption have resulted in more frequent reports of adverse reactions, highlighting the need for more specific diagnosis and treatment of seafood allergy. This review discusses recent literature in this field.

RECENT FINDINGS

The most recent prevalence data from Asia highlight seafood as a significant sensitizer in up to 40% of children and 33% of adults. Furthermore, the demonstration of species-specific sensitization to salt-water and fresh-water prawns and processed prawn extract should improve diagnosis. Studies on humans demonstrated for the first time that biologically active fish allergens can be detected in serum samples as early as 10 min after ingestion. These studies highlight that minute amounts of ingested seafood allergens can quickly trigger allergic symptoms; also, inhaled airborne allergens seem to induce sensitization and reactions. In the past 2 years, over 10 additional seafood allergens have been characterized. Allergen-specific detection assays in food products are available for crustacean tropomyosin; however, many specific mollusk and some fish allergens are not readily identified.

SUMMARY

Although cross-reactivity between crustacean and mollusks as well as mites is demonstrated, the often poor correlation of IgE reactivity and clinical symptoms calls for more detailed investigations. The recent development of hypoallergenic parvalbumin from carp could form the basis for safer vaccination products for treatment of fish allergy. Molecular characterization of more universal marker allergens for the three major seafood groups will improve current component-resolved clinical diagnosis and have a significant impact on the management of allergic patients, on food labeling and on future immunotherapy for seafood allergy.

Anisakis simplex: from obscure infectious worm to inducer of immune hypersensitivity

Infection of humans with the nematode worm parasite Anisakis simplex was first described in the 1960s in association with the consumption of raw or undercooked fish. During the 1990s it was realized that even the ingestion of dead worms in food fish can cause severe hypersensitivity reactions, that these may be more prevalent than infection itself, and that this outcome could be associated with food preparations previously considered safe. Not only may allergic symptoms arise from infection by the parasites ("gastroallergic anisakiasis"), but true anaphylactic reactions can also occur following exposure to allergens from dead worms by food-borne, airborne, or skin contact routes. This review discusses A. simplex pathogenesis in humans, covering immune hypersensitivity reactions both in the context of a living infection and in terms of exposure to its allergens by other routes. Over the last 20 years, several studies have concentrated on A. simplex antigen characterization and innate as well as adaptive immune response to this parasite. Molecular characterization of Anisakis allergens and isolation of their encoding cDNAs is now an active field of research that should provide improved diagnostic tools in addition to tools with which to enhance our understanding of pathogenesis and controversial aspects of A. simplex allergy. We also discuss the potential relevance of parasite products such as allergens, proteinases, and proteinase inhibitors and the activation of basophils, eosinophils, and mast cells in the induction of A. simplex-related immune hypersensitivity states induced by exposure to the parasite, dead or alive.