Immunomodulatory Effects Of Pasteurized ?-lactalbumin

?-lactalbumin is one of the most active substances in the milk,and it has been shown that it has the physiological functions of regulating immunity,inhibiting bacteria,resisting oxidation,resisting virus,and resisting tumor.In recent years,?-lactalbumin has been used in infant formula to adjust its nutritional structure.However,the effect of heat treatment on the immune activity of?-lactalbumin in cow milk processing is not clear.The article aims to study the immunomodulatory effects of pasteurized ?-lactalbumin and to explore its mechanism of action.While provides a reference for exploring the possible doses of alpha-lactalbumin in infant formula and the technical parameters of the thermal processing process to fully maintain its immunomodulatory activity.In this study,?-lactalbumin treated by pasteurization(heated at 62-65? for 30 min,72-75?for 15 s,82-85? for 15 s)and heated at 92-95? for 10 min was used as the research object.Then analyzed the effects of different heat treatment conditions on the secondary structure of?-lactalbumin,and also the digestive conditions of gastrointestinal tract were simulated to digest?-lactalbumin in vitro.Using HIEC as the cell model,the effect of ?-lactalbumin digestive juice on the proliferation of intestinal epithelial cells after heat treatment was studied,and the most effective way to promote the proliferation of HIEC was determined.Heat treatment of?-lactalbumin was carried out by the best heat treatment method selected by cell experiment.Four-week-old SPF SD rats were used as in vivo experimental studies to investigate their effects on body weight,spleen index and thymus index.Also it investigated the effects on the secretion of cytokines(IL-2,IL-4,IFN-? and TNF-?),immunoglobulin(Ig G,Ig M,Ig A),SIg A in colon,the activity of serum DAO and the quantity of goblet cells in colon of rats.The effect of heat treatment?-lactalbumin on immune regulation and the optimal dose were determined.The secondary structure of ?-lactalbumin treated with pasteurization and 92-95?/10 min was changed to a certain extent,among that the ?-lactalbumin treated at 72-75?/15 s and 82-85?/15 s,all ?-turns and part of ?-helix were converted to ?-fold and irregular curl,the most significant change was found in?-lactalbumin treated at 72-75?/15 s and 82-85?/15 s.?-lactalbumin hydrolysate within a certain range of concentration can effectively promote the proliferation of HIEC,increase the proportion of cells in S-phase and G2/M phase,increase the percentage of normal cell division,and decrease the rate of cell apoptosis.All effects was dose dependent.The results showed that ?-lactalbumin still had immunomodulatory activity after pasteurization and could regulate intestinal immunity by promoting the proliferation of intestinal cells.Through the proliferation of HIEC,it was proved that the optimum heat treatment method is 72-75?/15 s.Then,in the rat feeding test,?-lactalbumin treated at 72-75?/15 s increased the weight of rats and promoted their growth anddevelopment,the thymus index of rats was increased,and the its immunity was improved,the secretion levels of Ig A and cytokines IL-2,TNF-? and IFN-? in serum of rats were up-regulated,which indicated that ?-lactalbumin could enhance the blood immunity of rats.The number of goblet cells in the colon of the rat was significantly increased,the level of the secretion of SIg A in the colon was increased,and the activity of DAO in the serum was reduced,and it was proved that it has the function of protecting the intestinal mucosa barrier and improving the immune function of the intestinal mucosa.According to the results of blood immunity and intestinal immunity,100mg/kg·BW ?-lactalbumin has the best immunomodulatory effect.The results showed that the optimum heat treatment conditions for keeping immunomodulatory activity of ?-lactalbumin was 72-75?/15 s and the amount added is 100mg/kg·BW.