MicrobiologyOpen. 1, 373-380 (2012)

The results of our collaborative research with the Department of Fisheries, Faculty of Agriculture at Kinki University have been published in the MicrobiologyOpen. 

【Objective】

We examined the immunomodulatory effect of heat-killed Enterococcus faecalis TH10 (hk-TH10) on murine macrophage RAW264 cells.

【Methods】

We measured the amount of nitric oxide (NO) produced from a cell in order to examine the macrophage activity which is an index of activation of the innate immune system. We utilized Toll-like receptors (TLRs) which were knocked down by small interfering RNA (siRNA) in order to determine the pathway in cells where hk-TH10 stimulates macrophage activity.

【Results】

When we set lipopolysaccharides (LPS) which are known to be an enhancer of NO production in cells as a positive control, hk-TH10 stimulated NO production up to a level that is almost half of what LPS does. LPS is a strong enhancer. Therefore, we consider that hk-TH10 has a moderate macrophage activation potency.

According to the result from the experiment using siRNA, macrophage RAW264 cells recognized the passage of hk-TH10 through TLR-2 and TLR-6 pathways, and hk-TH10 stimulated NO production via the activation of NF-kB.