Characterization and Immunopotentiating Effects of the Glycoprotein Isolated from Dioscorea Batatas

Abstract

W e demonstrate that glycoprotein isolated from Dioscorea batatas (GDB) has immunostimulatory effects including macrophage activation. Analysis of infiltration of inflammatory cells into peritoneal cavity showed GDB treatment significantly increased the recruitment of macrophages, lymphocytes, neutrophils, and monocytes into the peritoneal cavity. Treatment of spleen cells isolated from C57BL/6 mice with GDB significantly increased the proliferation of B cells and T cells induced by LPS and ConA, respectively. Treatment with GDB significantly increased the cytolytic capacity of NK cells and macrophages against YAC-1 and B16 cells, respectively. In order to further confirm and investigate the mechanism of GDB on macrophage activation, we analyzed the effects of GDB on the cytokine expression including iNOS, IL-1β, and TNF-α in mouse macrophage cell line, RAW 264.7 cells. RT-PCR and ELISA showed that GDB increased the expression of IL-1β, and TNF-α, whereas iNOS was not induced by GDB. Collectively, this series of experiments indicates that GDB stimulates immune system including macrophage activation.

Immunomodulatory Activity of the Glycoprotein Isolated from the Chinese Yam (Dioscorea opposita Thunb)

“…YP‐1, a D. opposita Thunb polysaccharide, could stimulate Con A‐induced T lymphocyte proliferation (Zhao et al, ). D. batatas glycoprotein also exhibits immunopotentiating effects (Huong et al, ). In the present study, the immunoregulation activity and the underlying mechanisms of D. opposita Thunb glycoprotein were explored.…”

Synergistic Induction of iNOS by IFN-γ and Glycoprotein Isolated fromDioscorea batatas

“…Once activated, macrophages produce a number of cytotoxic molecules, such as, NO [9], which is also cytotoxic to certain tumor cells [28]. In a previous study, we found that GDB can exert significant immunomodulatory effects on specific immune responses mediated by macrophages, lymphocytes, and NK cells in vitro and in vivo [7]. GDB treatment of C57BL/6 mice caused a significant increase in the numbers of lymphocytes and macrophages in the peritoneal cavity, and both of these cell types play important roles in the first line of immunological defense against tumor cells.…”

“…Two proteins identified in D. alata tubers, dioscorins and phytoglycoproteins [33,34] are known to activate MAP kinases (ERK, p38, and JNK) and NF-κB via the TLR-4 signal transduction pathway and increases the expressions of pro-inflammatory cytokines, such as, TNF-α, IL-1β, and IL-6, in several cells including RAW 264.7 macrophages, murine monocytes, and human monocytes [4,35]. We previously isolated glycoprotein from Dioscorea batatas , and characterized and demonstrated its immunostimulatory activity [7]. …”

“…For isolation of the proteins, whole tubers were used. Glycoproteins were isolated from Dioscorea batatas according to the procedure of previously reported [7,20]. In brief, tubers were peeled and homogenized and subjected to hydrophobic chromatography on a phenyl-Toyopearl 650 M column (Tosoh, Japan) equilibrated with 50 mM Tris-HCl buffer (pH 7.0) containing ammonium sulfate to give 25% saturation.…”

“…Yam is an important crop, which is basically made up of carbohydrates but also constitutes an important source of proteins accounting for 1~3% of the fresh tubers [6]. We isolated glycoprotein from Dioscorea batatas , characterized, and demonstrated immunostimulating activity in C57BL/6 mice [7]. …”