Cell-line-based assay for the toxicity/benefit analysis of lipopolysaccharides in plants

There are many immune-boosting medicinal plants that can potently activate innate immune cells. Recent studies indicate that the active factors of some immune-boosting plants are lipopolysaccharides (LPSs) of plant-associated bacteria. However, little is currently known about the potential risk and benefit of LPSs in medicinal plants. To facilitate their characterization, we established a simple cell-line-based assay that can be used to screen the toxicity and benefit of LPSs in medicinal plants. The assay can distinguish endotoxic diphosphoryl lipid A (DPL) from beneficial monophosphoryl lipid A (MPL), which is a clinically used immunological adjuvant for vaccines. The established assay was used to characterize commercial supplements of Ashwagandha, which was shown to contain immunostimulatory LPSs. The study revealed that Ashwagandha activates macrophages in a manner similar to MPL. The current finding underscores the importance of further studies to characterize the LPSs in immune-boosting medicinal plants.