Mechanisms Of Host Epithelial Cells Mediate Antibiotic Tolerance In Extracellular Bacteria

The overuse and misuse of antibiotics have led to a global crisis of antibiotic resistance.However,past efforts on antibiotic resistance have focused on responses of individual cells and bacterial populations,which drying antibiotic pipeline further heightens the global threat created by antibiotic treatment failure.A critical approach to the problem is developing antibiotic tolerance under the interaction among host cells,pathogens and antibiotics,which can be provided some new strategies for investigation of antibiotic resistance.In addition,it has been long realized that antibiotic tolerance preceded resistance.Recent experiments show that antibiotic tolerance can facilitate the evolution of resistance.Herein,we illustrate a previously unknown mechanism of host cells mediated antibiotic tolerance.In this paper,we fist demonstrate that a wide range of extracellular bacteria including Bacillus cereus NVH0075/95,Enterococcus faecalis ATCC29212,Staphylococcus aureus ATCC29213,Streptococcus suis CQ2B50,Escherichia coli ATCC25922,Klebsiella pneumoniae 1202,Pseudomonas aeruginosa PAO1 and Vibrioparahaemolyticus ATCC17892 could survive in epithelial cells in both in vivo and in vitro models,including the intestinal epithelial cells from mouse infected models,two kinds of primary epithelial cells and four kinds of epithelial cell lines.Based on the comparison of extra-and intracellular MIC,it showed that such cells protect invasive bacteria to tolerate antibiotics covering all major classes.Secondly,bacterial virulence factors including Non-haemolysis enterotoxin(Nhe),Phospholipase C(Nhe)from B.cereus and a-toxin(AT)of S.aureus trigger cellular responses and promote bacteria invading into epithelial cells,which further facilitating the enhance of antibiotic tolerance.Furthermore,the inhibition of Nhe mediated Fas and ASK1 signaling pathway mediated by virulence factor decreased antibiotic tolerance by control of the invasive times.Finally,the routine,and often inappropriate,use of antibiotics can lead to cumulative exposure of low concentrations of antibiotics in host.In turn,our results demonstrate that such subinhibitory concentrations of antibiotics can,in the right context,enhance bacterial virulence factors by promoting pathogens to invade in the cytoplasm of nutrient limitation.On another side,antibiotics facilitate intracellular survival of bacteria by inducing autophagy arrest to further maintain cell-mediated antibiotic tolerance.Conclusively,our papar illustrated that host epithelial cells mediate antibiotic tolerance in extracellular bacteria.Such tolerant bacteria are often acting as "Trojan horses" to against antibiotic therapy and have better division of labor(DOL)during bacterial infection.On one hand,compared to antibiotic resistance that are sophisticatedly modulated by genetic accessories,extracellular bacteria hide in epithelial cells providing an economic way to sustain antibiotic stresses without genetic cost.One the other hand,the invasive bacteria in cells are much easy to penetrate the first barrier of host defense system before dissemination.Thus,the main research purpose of host epithelial cells mediate antibiotic tolerance in extracellular bacteria is to develop new antibiotic strategies and further prevent the evolution of tolerance may shed light on alternative strategies for antibiotic treatments.