|Meydani, Simin N.|
|Wu, Dayong S.|
Submitted to: British Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/10/2012
Publication Date: 2/1/2013
Citation: Xu, Y., Na, L., Ren, Z., Xu, J., Sun, C., Smith, D., Meydani, S., Wu, D. 2013. Effect of dietary supplementation with white button mushrooms on host resistance to influenza infection and immune function in mice. British Journal of Nutrition. 109:1052-1061. Interpretive Summary: Optimal function of the immune system is critical for preventing and controlling invading organisms that can cause disease or abnormal cells that can develop into cancer. Although strategies to control the immune system’s function are limited, the intake of essential nutrients and functional foods has become an increasingly favored approach to improving immune cell function. White button mushrooms (WBM) are a promising functional food because of their ability to affect immune cell function. Results from two of our previous studies suggest that white button mushrooms enhance the body’s natural immune function and may promote the development of acquired or learned immune response. In this study, we tested if WBM could protect young and old mice against viral infection. We learned that WBM did not affect the level of virus, and it did not prevent infection-induced weight loss. However, WBM enhanced the immune response in old and young mice prior to infection but it did not show major positive benefits to the immune response after infection. This study suggests that WBM supplementation may have the potential to strengthen the immune system given its ability to enhance its response prior to infection. The fate of an infection for the large part depends on the interaction of the host’s immune system and the pathogens or harmful microbes invading it. This study provided useful information showing that improved functions for certain immune cells to a certain extent are not adequate enough to make a difference in fighting influenza (flu) infection. Therefore, the observed improvement in immune function should be confirmed based on actual protection in case of infection. Further research could be done to explore whether white button mushroom effectiveness depends on the types of harmful germs the host is exposed to and whether white button mushrooms can improve the effectiveness of vaccinations, thus improving protection for any future influenza infections since in the broad picture, influenza continues to cause serious illness and death worldwide.
Technical Abstract: Previously we showed that mice fed white button mushrooms (WBM) had enhanced immune functions known to help the body’s antiviral defense. In this study, we tested if WBM could afford protection against viral infection. Young (4-mo) and old (22-mo) C57BL/6 mice were fed a diet containing 0, 2 per cent, or 10 per cent WBM powder for 8-wk. The mice were then infected with influenza Puerto Rico/8/34 (H1N1), and killed at day 0 (uninfected), 2, 5, or 7 post-infection. The primary outcomes of the study are viral titer and body weight. Secondary outcomes are natural killer (NK) cell activity, lymphocyte proliferation, and cytokine production. Results showed that WBM did not affect viral titer, nor did it prevent infection-induced weight loss. WBM supplementation was found to enhance natural killer (NK) cell activity in old mice and to increase IFN-gamma production in young and old mice under naive (uninfected) conditions but it had no such effect after infection. The lack of a mushroom supplementation effect on NK activity and IFN-gamma production after infection may explain the immune system’s failure to reduce viral load and weight loss in the mice after influenza infection. WBM supplementation, however, did induce changes in other aspects of the immune response: it significantly increased production of Th2 cytokines IL-4 and IL-10 in uninfected mice and pro-inflammatory cytokines IL-1beta and TNF-alpha in infected mice. These mushroom-induced systemic changes, however, were not adequate to confer a protective effect against influenza infection.