Probiotic Bacterium Stimulate the Immune Response of Caenorhabditis elegans through Nuclear Hormone Receptor

Even though the immune response of Caenorhabditis elegans to pathogen infections is well established, very little is discovered about the impacts of health promoting-probiotic bacteria on C. elegans host responses. We determined on the survivals of C. elegans by plate method and transmission electron microscopy (TEM). In addition, we employed DNA microarray, quantitative real time-polymerase chain reaction (qRT-PCR), and transgenic worms assay for exploring health-promoting pathways via probiotic bacteria in C. elegans. We showed that conditioning with L. acidophilus strain A4 strongly colonized in the C. elegans nematode intestine (plate count and TEM image), significantly enhanced the resistance of nematodes exposed to Staphylococcus aureus as well as prolonged the lifespan of C. elegans. Importantly, whole transcriptome analysis and transgenic worm assays showed that health-promoting effects of L. acidophilus strain A4 were mediated by the presence of nuclear hormone receptor (NHR) family. Taken together, we describe a new C. elegans based system for the screening of novel probiotic activity and our findings demonstrate that pre-conditioning with probiotic bacterium L. acidophilus strain A4 may positively stimulate the longevity and resistance to foodborne pathogen infections of C. elegans host.