Ovalbumin Delivery by Guanidine-Terminated Dendrimers Bearing an Amyloid-Promoting Peptide via Nanoparticle Formulation.

Development of protein delivery systems is important for biomedical applications such as immunotherapy. Ovalbumin (OVA) is a major component of egg whites, and is a possible cause of egg allergy. In this study, OVA was used as a model protein to develop a delivery system using guanidine-terminated dendrimers (Gdn-den) bearing an amyloid-promoting peptide derived from the helix B (hB) region of OVA (hB-Gdn-den). OVA nanoparticles (NPs) were prepared by heat treatment of OVA/hB-Gdn-den mixtures. The NP size and the surface charge were controlled by adjusting the ratio of hB-Gdn-den to OVA. The NPs were around 200 nm in diameter and stably dispersed, and their encapsulation efficiency for OVA was more than 80%. Although OVA NPs were also prepared using Gdn-den, the NPs aggregated readily. Complexation with hB-Gdn-den induced conformational changes in the OVA, and the hB peptide promoted digestion of OVA. These suggest that the hB peptide of the Gdn-den works as a possible anchor to OVA. The positively charged OVA NPs effectively associated with RAW264 cells. Thus, the amyloid-promoting Gdn-den, when mixed with OVA at a suitable molar ratio to form NPs, could act as a carrier for delivery of antigen proteins to immune cells.

[A case of immediate allergy to anisakis following saury intake].

We report here a 76-year-old male that presented with an immediate allergy to Anisakis following saury intake. Three and a half hours after eating pressed saury sushi, whole-body pomphus appeared including itching, facial dropsical swelling, and dyspnea. Diagnostic tests revealed specific IgE antibodies against anisakis simplex and a skin prick test was positive using an extraction of anisakis simplex. The results of skin prick tests using the body and internal organs of a saury were negative. Based on these results, we diagnosed the case as immediate allergy to Anisakis. Anisakis is parasitic to a diverse array of fish, and it seems rare that eating saury will induce an allergic response because the reported parasitic rate of Anisakis on saury is only 5%. In addition, as tropomyosin is currently considered to be the primary cause of allergies to Anisakis, renewed attention should be paid to other foods for which tropomyosin is also assumed to be a common antigen.

Role of the N-terminal amphiphilic region of ovalbumin during heat-induced aggregation and gelation.

Ovalbumin (OVA), a major globular protein in egg white, forms semiflexible fibrillar aggregates during heat-induced gelation. The N-terminal amphiphilic region (pN1-22) of OVA is removed after treatment with pepsin at pH 4 to leave a large OVA fragment (pOVA). The conformation and thermal stability of pOVA and OVA are similar, but the rheological strength of the heat-induced gel of pOVA is much lower compared to that of OVA. The aggregation rate of pOVA, which forms spherical aggregates, was lower than that of OVA. These results suggest that the N-terminal amphiphilic region of OVA facilitates the α-to-ß conformational transition, which triggers OVA fibril formation. Heat treatment of OVA in the presence of pN1-22 consistently resulted in the formation of straight fibrils. The strength of OVA and collagen gels was increased when prepared in the presence of pN1-22, suggesting that pN1-22 may be used to control the properties of protein gels.