Insight into the allergenicity of digestion-resistant epitopes in Antarctic krill (Euphausia superba) tropomyosin

The allergenic potential of four digestion-resistant linear epitopes (EADRKYDE, ERAEERAEAG, RSVQKLQKEVDR, and VNEKEKYKGI) in Antarctic krill tropomyosin was investigated through in vivo and in vitro experiments. Mice induced by the four epitopes exhibited obvious clinical allergic symptoms, with significant increases in serum specific antibody levels and blood lymphocytes, neutrophils, and eosinophils (p < 0.05). Additionally, mast cells exhibited pronounced degranulation, as well as increased release of histamine and mMCP-1, and enhanced vascular permeability. Mice challenged with the four epitopes further displayed severe pathological damage. In contrast to the antagonistic effect of interleukin-4 and interferon-gamma in the plasma of mice in previous studies, stimulation of the epitopes resulted in immune system dysregulation in mice, with significant increases in the levels of interleukin-4 and interferon-gamma to 110.03 pg/mL and 103.59 pg/mL, respectively. The enhanced binding ability of the four epitopes to IgE was also indicated in vitro. The four digestion-resistant epitopes are the major factors to the allergenicity of tropomyosin and have strong sensitizing abilities. This study provides a theoretical basis for using site directed mutagenesis to reduce the allergenicity of tropomyosin in Antarctic krill.