Effects Of Ovotransferrin On Intestinal Immunoregulation In Immunosuppressed Mice

Ovotransferrin(OVT)is the major protein in avian egg whites,which is rich in a variety of biologically active functions.As the main place for digestion and absorption of nutrients,the intestine serves as a barrier between the external environment of the body and the internal environment.The balance of immune function is essential for the health of the body.The purpose of this study was to investigate the effect of OVT on intestinal immune regulation in immunosuppressed mice induced by cyclophosphamide(CP),and provide a theoretical basis for its application in nutraceutical foods and fortified foods,which has an important academic value and broad application prospects in the in-depth development of avain eggs.In addition,the results of the study are expected to reveal the relationship between dietary nutrients,intestinal immune function and microbial flora.Sixty female SPF Kunming mice were randomly divided into five groups after one week of adaptation: Control group,model control group,OVT low,medium and high dose groups.After 3 days of intraperitoneal injection of CP(80 mg/kg)for immunosuppression,the low,medium and high doses of OVT were administered at 2 mg/kg,20 mg/kg and 2mg/kg.The control group and CP group were administered with physiological saline intragastrically and the time of gavage lasted for 7 days.After the experiment,the blood,spleen,thymus,small intestine and the contents of intestines in the mice were collected.Molecular biology techniques were used in this study,such as flow cytometry,ELISA,RT-PCR,Western-blot were used to detect the maturation of intestinal dendritic cells,the expression of cytokines and their genes,the secretion of immunoglobulins and the expression of MAPK-related proteins.The pathological changes of intestinal tissues were observed by HE staining.The 16 S rDNA high-throughput sequencing technology and PICRUSt were used to analyze the structural changes of intestinal microflora and the functional metabolism of intestinal microflora,which investigated the regulation of OVT on intestinal immune function in immunosuppressed mice and the results are as follows:(1)Establishing a mouse model of immunosuppression by CP,which explored the effect of OVT on immune organs and body weight of immunosuppressed mice.The study found that OVT could slow down the weight loss of immunosuppressed mice and significantly increased the thymus index and spleen index of immunosuppressed mice(p <0.05).The results indicated that OVT has the function of improving the immune regulation function of the mouse.(2)Establishing a mouse model of immunosuppression by CP,which investigated the effect of OVT on intestinal immune regulation in immunosuppressed mice.The study found that OVT promoted the maturation of intestinal DCs and significantly increased the expression of DCs-related phenotypes MHC-II and CD83(p < 0.01).OVT also promotedthe expression of cytokines and its mRNA,the secretion of TNF-α,IL-10 and IgA in mouse serum increased(p < 0.05),and increased the expression of TNF-α,IFN-γ,IL-4 and IL-10 and their mRNA in intestinal tissues(p < 0.05);In addition,OVT significantly up-regulated the expression of sIgA in IgA and intestinal contents in intestinal tissues(p <0.05).Meanwhile,OVT significantly inhibited phosphorylation of p38,JNK,ERK in intestinal tissues of immunosuppressed mice(p < 0.01).The results indicate that OVT has the ability to improve the intestinal immune regulation function of immunosuppressed mice induced by CP.(3)Establishing a mouse model of immunosuppression by CP,which was to explore the repair effect of OVT on intestinal damage.The histopathological section of the intestine was observed by HE,it was found that OVT could improve the intestinal mucosal structure,promoted the increasing of intestinal villi and crypt length,repaired the vacuole deformation inside the intestinal villi caused by CP.The results indicated that OVT had the ability to repair intestinal mucosal damage in immunosuppressed mice induced by CP.(4)Establishing a mouse model of immunosuppression by CP,which was to explore the regulation of OVT on the structural disorder of intestinal flora caused by CP.The results showed that OVT significantly increased the expression of Shannon and Simpson in Alpha diversity index(p < 0.05),which incidated that OVT could increase the diversity of intestinal microflora.In addition,OVT significantly inhibited the relative abundance of Helicobacter and Desulfovibrio(p < 0.05).The expression level of relative abundance of Lachnospiraceae-NK4A136-group was promoted(p < 0.05).Meanwhile,OVT also significantly improved the inhibition of carbohydrate metabolism by CP by using PICRUST analysis(p < 0.05).The comprehensive results showed that OVT could improve the structure of intestinal flora in immunosuppressed mice.