Anti-food Allergy Activity Of R-phycocyanin From Porphyra Haitanensis

In the last several decades, the prevalence of food allergies has increased in several regions throughout the world. Food allergy always results in series of symptoms mostly involving skin,gastrointestinal and respiratory tract, seriously endanger the allergy sufferer's life. There is a new study trend to prevent or treat food allergy via the development of new type of anti-allergic substance. R-phycocyanin(RPC) is a kind of photosynthetic pigment in red alga which plays the role of radiosity in the process of photosynthesis. Previous study showed that RPC exhibited immunoregulatory functions, whereas the function of anti-food allergy of RPC extracted from Porphyra haitanensis has not been identified. The exploration of anti-food allergy activity of RPC and intensive study of its mechanism has important implications for the development of new health care products or bulk pharmaceutical chemicals.In this article, the major allergen tropomyosin(TM) in Scylla paramamosain was purified by methods such as ammonium sulfate fractionation and isoelectric precipitation. The 38 kDa protein extracted from the salt soluble myofibril was identified as TM by Western-blotting. Then the anti-food allergic component RPC from Porphyra haitanensis was purified by ammonium sulfate fractionation and column chromatography. The purity of RPC was detected as A620/A280 > 6.0. Two characteristic absorption peaks 617 nm and 555 nm detected by ultraviolet spectrophotometry were used to be the identification of RPC. There was only one single band showing in the Native-PAGE. SDS-PAGE showed that the protein consisted of two different aubunits, molecular weight respectively about 17.7 kDa and 20.5 kDa.For evaluating the anti-allergic effect of RPC, the food allergy murine model was established by intraperitoneal injection of TM. The animal experiment result showed that the IgE level after the secondary immunization was 3 times more than before immunization.The histamine content in mouse serum and feces reached about 150 ng/mL, 15 ?g/mg, and there is significant difference between PBS and TM group. That's the evidence of establishing the food allergy murine model successfully. On the contrary, RPC could significantly decrease the TM-specific IgE level in mouse serum and histamine content in mouse serum and feces. The preliminary report showed that R-phycocyanin had anti-food allergic activity. Afterwards, mouse spleen lymphocytes were isolated and stimulated by TM mixed RPC. The protein secretion and gene expression of cytokines in cultural supernatants were detected. The cell experiment result showed that TM could promote the secretion and gene expression of TH2-type cytokines IL-13(120 pg/mL) ? IL-4(300 pg/m L), meanwhile, RPC could decrease the secretion and gene expression of TH2-type cytokines but increase the secretion and gene expression of TH1-type cytokines. In addition, this regulating effect had dose-response relationship. By inference, RPC exhibited anti-food allergy functions in regulating TH cell polarization to TH1 type. In this research, RPC had more obvious effect on IFN-? production(1600 pg/mL), so the inhibitors of the phosphokinase were used to explore the the effects of cellular factors on the production of IFN-? induced by RPC. The result showed that through the JAK2 and JNK pathway, IFN-?synthesis is induced by RPC.In conclusion, high purity RPC extracted from Porphyra haitanensis could reduce serum specific IgE and histamine level and exhibited anti-food allergy functions in regulating TH cell polarization to TH1 type. Through the JAK2 and JNK pathway, IFN-? synthesis is induced by R-phycocyanin.