Effect Of Lactobacillus Plantarum Y44 On The Antioxidative Function Of Human Intestinal Epithelial Eell Model Caco-2

Reactive oxygen species(ROS)are continuously produced in human body and participate in many pHysiological metabolic behaviors.ROS-mediated oxidative stress is closely related to the occurrence of various diseases among them,inflammation is the most common disease.Lactic acid bacteria are one of the most familiar probiotics with a long history of use.Certain Lactobacillus bacteria and the fermented foods they are involved in(such as yogurt and sauerkraut,etc.)have been proven to have good probiotic benefits.Numbers of studies have shown that lactic acid bacteria have probiotic properties,including antioxidant and anti-inflammatory functions.In our previous work,the strain Lactobacillus plantarum Y44 with antioxidant activity was screened.Firstly,the antioxidant activities of L.plantarum Y44 were further studied by some chemical antioxidant methods,including DPPH free radical,Hydroxyl free radical,ABTS free radical scavenging assay,Ferric ion reducing antioxidant power(FRAP)test and oxygen radical absorption capacity(ORAC)test,and Caco-2 cell model with ABAP injury.Experiments show that L.plantarum Y44 can effectively scavenge oxygen free radicals.Correlation analysis between antioxidant experiment results and L.plantarumY44 bacterial concentration,it was found that the antioxidant function of L.plantarum Y44 is positively correlated with the bacterial concentration(p<0.05),that is,the higher the bacterial concentration,the better the antioxidant performance.However,when the concentration of L.plantarum Y44 strain is 10~100 cfu/mL,it has certain damage to cells.When the concentration of L.plantarum Y44 strain was 10~9 cfu/mL,the highest CAA value was observed and the survival rate of Caco-2 cells damaged by ABAP was significantly increased(p<0.05).The results of chemical antioxidant experiments and CAA test were consistent with the results of L.plantarum Y44 protecting Caco-2 cells from ABAP oxidative damage.L.plantarum Y44 strain can enhancing the barrier function of Caco-2 cells by up-regulating the expression of?-Catenin and E-Cadherin protein in Caco-2 cells,and then prevent the damage of Caco-2 cells by ABAP.Scanning electron microscopy showed that L.plantarum Y44 protected the integrity of Caco-2 cells under oxidative stress.L.plantarum Y44 significantly down-regulated the expression of proinflammatory cytokines IL-8 and TNF-?in ABAP-induced Caco-2 cells(p<0.05),and L.plantarum Y44 pretreated Caco-2cells significantly inhibited the nuclear translocation of NF-?B p65 protein and the ubiquitination of I?B protein in Caco-2 cells induced by ABAP(p<0.05),the results indicate that L.plantarum Y44 can alleviate the symptoms of Caco-2 cell inflammation caused by ABAP.L.plantarum Y44 strain significantly promoted the expression of Nrf2 protein and HO-1 protein in Caco-2 cells Nrf2 signaling pathway(p<0.05),and significantly promoted the expression of cellular catalase(CAT)(p<0.05).Based on the results of this study,it was estimated that L.plantarum Y44 exerted antioxidative effects by quenching oxygen free radicals and activating expression of Nrf2signaling pathway-associated proteins and protecting the cell barrier function of Caco-2 cells to to improve the antioxidant function of Caco-2 cells in human intestinal epithelial cell model.