|Authors: ||Y. Oritani, E. Nishimura, H. Inagaki, T. Ito|
|Keywords: ||innate immune system, defensin, TLR, PAMPs, reporter gene assay|
Manchurian wild rice (Zizania latifolia; ZL) is a vegetable broadly eaten in Asian countries, especially in China.
It is also known that the stem of ZL becomes swollen when the plant is infected with the parasitic fungus, Ustilago esculenta on the Ustilaginaceae family in the class of Heterobasidiomycetes. People have been cultivating this plant and eating the swollen shoots for more than 400 years.
It is traditionally said that ZL has immunostimulating effects.
However, its biological effectiveness and pharmacological mechanism has not yet been proved.
The immune system can be divided into two major categories: innate immunity and adaptive immunity.
The innate immune system confers non-specific protection against a large number of pathogens, hence, serving as the first line of host defense mechanisms.
The immune system utilizes signal from toll-like receptors (TLRs) that bind and recognize microbial components.
ZL includes microbial components from Ustilago esculenta. Therefore we have focused on the immunological stimulation activity of ZL. We adopted the expression of hBD-2 as an indicator of innate immune activation.
Human -defensin (hBD-2), the peptide responsible for innate immunity, is known to play a pivotal role in front defense against bacterial infection and it is induced by microbial components in epithelia.
In this study, we investigated the hBD-2 in human colon carcinoma cells (Caco-2), quantified by reporter gene assay at 12 hours post-stimulation by heat treated ZL. As a result, when Caco-2 cells are stimulated by 0.01% ZL, the promoter activity of hBD-2 was about 4-fold higher than the negative control.
ZL may contribute to human health through activating the expression of genes related with the innate immune system.
Download Adobe Acrobat Reader (free software to read PDF files)