Live Combined Bifidobacterium And Lactobacillus Tablets Prevents Escherichia Coli K1 Infection Via Enhancing Intestinal Defense

BACKGROUND AND AIMSEscherichia coli meningitis is a severe infection characterized by high rate of mortality in neonates.Antibiotic resistance has become a major health issue affecting public health,especially the abuse of antibiotics,which may aggravate the infections of E.coli with antibiotic resistance in neonates.Therefore,the development of non-antibiotic strategies prevents against infections of E.coli with antibiotic resistance in neonates has emerged as an urgent issue.Currently,more and more evidences suggest that probiotics could be used to keep homeostatic balance of intestine and enhance integrity of the intestinal barrier.Our rcent research has shown that Live Combined Bifidobacteriμm and Lactobacillus Tablets(contain living lactobacillus bμlgaricus,Bifidobacterium,and streptococcus therrnophilus,LBS)could prevent the E.coli meningitis in neonatal rats,but the really mechanism is not clear.The aim of this study was used HT-29 and neonatal rats as in vitro and in vivo experimental model to investigate the mechanism of LBS exert inhibitory effect against E44 infection and wheather the E44 could disrupt the intestinal barrier.METHODS AND RESULTSIn this study,HT-29 cells and neonatal rats were used to establish an intestinal barrier model in vitro and in vivo.There are four groups in our study:PBS,LBS,E44,LBS plus E44.1、Competitive inhibition experiments to prove the effect of LBS on adhesion and invasion of HT-29 cells by E44 in vitro.We found LBS could inhabite the adhesion and invasion of E44 to HT-29 cells in a dose dependent.On the other hand,we also found pre-incubation with LBS resulted a decrease in invasion/adhesion rate compared with the co-incubation with LBS.2、E44 could increase the cytotoxic and apoptosis rate of HT-29 cells and pre-treatment with LBS could reduce the rate of cytotoxicity and apoptosis induced by E44 which meaned LBS could protect the epithelial cells.3、PAS assay showed that E44 could degrade Mucin and LBS could inhibit the degradation of Mucin by E44.Meanwhile LBS could also promote the expression of Mucin.4、The intestinal permeability and intercellular tight junction protein study showed that E44 could disrupt the tight junction between cells and increase the intestinal permeability;LBS could effectively inhibit E44 disruption tight junction proteins and reducing intestinal permeability,which meaned LBS could protect the intestinal integrity.5、In vivo,few ki67-positive cells and IgA production in E44 infected neonatal rats group;LBS could improve the expression of IgA and ki67-positive cells in the intestinal tract.CONCLUSIONS1、E44 could degrade the Mucin,injure the intestinal epithelial cells,disrupt the intestinal integrity to destroy the intestinal barrier.2、LBS could inhabite the adhesion and invasion rates of HT-29 cells and the preventive effect of LBS was superior to its co-incubation effect.Thus the following experiments were all used LBS for pretreatment.3、LBS could maturate the intestinal defense to prevent Escherichia coli bacteremia and meningitis.