Immune enhancing Echinacea bacterial endophytes
A growing body of evidence from our lab suggests that endophytic bacteria within Echinacea are the main source of components responsible for enhancing innate immune function in vitro and in vivo. We have found that 97% of in vitro monocyte/macrophage activation by extracts of Echinacea and other immune enhancing botanicals is due to the bacterial components LPS and Braun type lipoproteins. Furthermore, we have found that changes in the levels of these two components are responsible for the variation (˜100-fold) observed in the activity of Echinacea material obtained from different commercial sources. In the current research we identified the endophytic bacteria associated with roots and aerial material of commercial and freshly harvested E. purpurea plants. Although community composition analysis of commercial, wild, and locally cultivated Echinacea showed wide variation, the total bacterial load was significantly correlated with macrophage activation for each group (R2= 0.50 p = 0.015, R2= 0.85 p = 0.0009, and R2= 0.63 p = 0.018 respectively). In addition, over 150 endophytic bacterial isolates were cultured from live Echinacea samples. Extracts from these isolates varied substantially in their ability to activate macrophages in vitro indicating that type of bacteria is important for overall macrophage activation potential of this botanical. We also evaluated whether agronomic factors (soil organic matter, nitrogen fertilization and soil moisture) could cause shifts in endophytic bacterial type/amount that would result in activity changes.
Acknowledgements: This research was partly funded by a grant number R01AT007042from the NCCAM and ODS. Additional funding was also provided by the USDA, ARS Specific Cooperative Agreement Nos. 58 – 6408 – 6-067 and 58 – 6408 – 1-603.