Effects Of Pasteurized Bovine Lactoferrin On Immunity

At birth,intestinal development in infants is not mature,and immune development is slow.Consequently,they are more susceptible to various diseases,such as necrotizing enterocolitis.Breast milk contains a variety of biologically active ingredients that ensure proper development of the gut system in infants.One of the important components,lactoferrin(LF),releases biologically active peptide,lactoferricin(Lfcin),by enzymatic hydrolysis of the digestive tract.Studies have shown that lactoferrin has the ability to resist fungal and pathogenic infections,slow down the inflammatory response,fight cancer and improve the body's immune regu lation,especially in promoting intestinal immunity.At present,many countries inclu ding China have used LF as an important component of infant formula.In the past two years,there has been growing interests among Chinese consumers in pasteurized milk,owing to desirable characteristics of LF,such as maintaining the nutrition,flavor and biological active ingredients of fresh milk.This study aims to explore the effects of different pasteurization conditions on the immunological activity of LF,establish the best pasteurization parameters to maintain its biological activity,and explore its effective dose to improve the immunity of infants,which will provide new evidence for a more scientific and precise development of modern dairy processing technology.In this study,we used bovine lactoferrin(LF)hydrolysate from infants digestion environment to investigate its effects on on cell proliferation,cycle,apoptosis and cycle related gene expression of rat intestinal crypt epithelial cells(IEC-6)and in vitro cell experiments to determine the optimal pasteurization conditions and dosage range of lactoferrin.According to the data obtained from in vitro experiments,combined with the content of LF in breast milk,we selected three appropriate high,medium and low doses to feed SD male rats Using blood and intestinal immunity indices,we explored the effects of LF on immune-reactivity to determine the appropriate pasteurization processing.Experimental results show:(1)In vitro cell experiments,after infants digestion environment,bovine LF hydrolysate can increase the expression level of cycle-related genes cyclin B1,CDK1 and cyclin E1,and reduce the expression level of p21,thereby regulating cell cycle distribution,increase the distribution of IEC-6 cells in G2/M phase and S phase,reduce the distribution of cells in G 0/G1 phase,promote IEC-6 cells proliferation,and slow cell apoptosis.At 72°C/15 s and 85°C/15 s,the immunological activities of lactoferrin retention were maximized,and the optimal dose to promote intestinal immunization in infants is 0.1 mg/m L.(2)In the animal experiment,bovine lactoferrin under two treatment modes(unheated and 85°C/15s)has enhanced effects on blood immunity and intestinal immunity.Lactoferrin can increase the secretion of IL-2,IL-4,IFN-? and Ig M,up-regulate the ratio of IFN-?/IL-4 in rat serum,and maintain the dynamic balance of Th1 and Th2 cytokines.By reducing the activity of DAO in rat serum,increasing the secretion of s Ig A in rat colon and increasing the expression level of Occludin and ZO-1 genes in rat colon,lactoferrin can reduce intestinal mucosal permeability and improve rat intestinal channel barrier function and immune function;(3)Based on blood immunization and intestinal immunity results,the 85°C/15 s had no significant destructive effect on the immunologically active lactoferrin group.The best optimal dose was 60 mg/kg·BW.Although pasteurization partially damages the immunologically active group of lactoferrin,it does not reduce its biological activity.Pasteurization 85°C/15 s is the best pasteurization condition to retain the immune activity of immune protein in raw milk.(4)With the increase of experimental time,the enhanced effect is more significant.It indicates that the effects of lactoferrin for the immune regulation of the body can be a long-term.The 85°C/15 s level is the best sterilizing condition for retaining the immune activity of immune protein in raw milk.This provides a theoretical basis for the design of processing parameters and the amount of nutritional supplements in the current stage of dairy products,a nd at the same time it guides the development direction of fresh milk products at the national level.