An Echinacea purpurea root extract modulates macrophage activation and polarization in response to infection

Echinacea preparations are traditionally used for the prevention and treatment of upper respiratory tract infections. Although immunomodulatory properties have been described, notably on innate immunity, effects remain dependent on the phytochemical composition of the extract used, itself a function of the species and part of the plant used, as well as the method of extraction.

We investigated the immunomodulatory properties of a standardized hydroethanolic extract of fresh roots of Echinacea purpurea (patented process Phytostandard®; hydroethanolic root extract [HRE], PiLeJe Laboratoire) on peritoneal macrophage activation and polarization in response to LPS and Streptococcus pneumoniae. C57BL/6 mice were orally treated once daily with HRE or phosphate-buffered saline (n=10/group) for 14 days and then intraperitoneally injected with LPS (0.5mg/kg). Twelve hours after LPS injection, activation of macrophages was assessed by flow cytometry and RT-qPCR. Ex vivo microbicidal functions of macrophages were

evaluated against Streptococcus pneumonia (phagocytosis and killing by fluorescence and CFU quantification, respectively).

Interestingly, the HRE decreased inflammatory response to LPS and induced changes in immune cell populations by increasing the percentage of small peritoneal macrophages and decreasing that of systemic classical monocytes. Regulation of macrophage gene expression was also observed; HRE decreases pro-inflammatory cytokines, increases C-type Lectin receptors and CD36, LTB4 metabolism pathway. Our findings show that bactericidal activity against S. pneumoniae was significantly increased in macrophages isolated from mice supplemented with HRE versus PBS.

Altogether, our results suggest that the HRE of E. purpurea tested strengthens innate immunity against invading pathogens while limiting the inflammatory process.

Publication History

Article published online:
13 December 2021