Korean Red Ginseng enhances pneumococcal Δpep27 vaccine efficacy by inhibiting reactive oxygen species production.

Streptococcus pneumoniae, more than 90 serotypes of which exist, is recognized as an etiologic agent of pneumonia, meningitis, and sepsis associated with significant morbidity and mortality worldwide. Immunization with a pneumococcal pep27 mutant (Δpep27) has been shown to confer comprehensive, long-term protection against even nontypeable strains. However, Δpep27 is effective as a vaccine only after at least three rounds of immunization. Therefore, treatments capable of enhancing the efficiency of Δpep27 immunization should be identified without delay. Panax ginseng Mayer has already been shown to have pharmacological and antioxidant effects. Here, the ability of Korean Red Ginseng (KRG) to enhance the efficacy of Δpep27 immunization was investigated.

Mice were treated with KRG and immunized with Δpep27 before infection with the pathogenic S. pneumoniae strain D39. Total reactive oxygen species production was measured using lung homogenates, and inducible nitric oxide (NO) synthase and antiapoptotic protein expression was determined by immunoblotting. The phagocytic activity of peritoneal macrophages was also tested after KRG treatment.

Compared with the other treatments, KRG significantly increased survival rate after lethal challenge and resulted in faster bacterial clearance via increased phagocytosis. Moreover, KRG enhanced Δpep27 vaccine efficacy by inhibiting reactive oxygen species production, reducing extracellular signal-regulated kinase apoptosis signaling and inflammation.

Taken together, our results suggest that KRG reduces the time required for immunization with the Δpep27 vaccine by enhancing its efficacy.