Abstract
We have found that the bacterial components lipopolysaccharides (LPS) and Braun-type lipoproteins are responsible for the majority of the in vitro macrophage activation exhibited by extracts of Echinacea and other immune enhancing botanicals. Furthermore, we show that endophytic bacteria are the principal source of these components. We also show that total bacterial load within Echinacea samples are strongly correlated with the innate immune stimulatory activity (NF-κB activation in THP-1 cells) and content of bacterial LPS within extracts of this plant material. Differences in the levels of these two bacterial components are responsible for the substantial variation observed (˜200-fold) in innate immune cell activation from E. purpurea material obtained from six major growers/commercial suppliers in North America. This substantial variability in bacterial component content/activity could be a factor contributing to the inconsistent outcomes exhibited in Echinacea clinical trials. We also demonstrate that the oral consumption of extracts rich in these bacterial components is therapeutically relevant with respect to enhancing immune parameters and for impacting disease outcomes in both animal models and in humans. Acknowledgements: This research was partially funded by grants from the National Institutes of Health R21AT01207, R01AT002360 and R01AT007042 (NCAAM) to DSP and by the USDA, Agricultural Research Service Specific Cooperative Agreement No. 58 – 6408 – 02 – 1-612.
Published Version
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