Newly developed evaluation for intestinal permeability using <i>Caenorhabditis elegans</i>: protective effects of agaro-oligosaccharides on intestinal permeability

The intestinal barrier represents the first line of host defense. Its dysfunction, defined as increased intestinal permeability, is widely recognized as an important factor in the clinical manifestation of various diseases. Consequently, maintenance of the intestinal barrier is necessary for human health. <i>Caenorhabditis elegans</i> has recently been used frequently as a model organism in studies of gut bacteria-host interactions and in screening for probiotics and prebiotics that promote gut health. Nevertheless, no quantitative method for evaluating the intestinal permeability of <i>Caenorhabditis elegans</i> has yet been established. This study assesses a newly developed evaluation method to assess the intestinal permeability of <i>Caenorhabditis elegans</i> quantitatively using liposomes encapsulating fluorescein isothiocyanate-dextran. The usefulness of this method was confirmed by measuring the intestinal permeability of <i>Pseudomonas aeruginosa</i>-infected or oxidative stress-induced worms. Furthermore, our method found that agaro-oligosaccharides, the hydrolysis products of agarose, have a beneficial function of preventing increased intestinal permeability. This approach can expand the utility of <i>Caenorhabditis elegans</i> for functional food discovery and drug candidate screening, with specific examination of their effects on gut function.