Stimulatory effect of a pectic polysaccharide from a medicinal herb, the roots of Bupleurum falcatum L, on G-CSF secretion from intestinal epithelial cells

The inner surface of the intestinal tract possesses a large area of mucosal membranes, and the intestinal epithelial. cells exist at the interface between an antigen-rich lumen and a lymphocyte-rich lamina propria. The crosstalk that occurs between these compartments serves to maintain intestinal homeostasis, and the cytokine network plays an important role in the crosstalk. In this study, the effect of a pectic polysaccharide, bupteuran 2llc from Bupleurum falcatum L., on cytokine secretion of intestinal epithelial. cells was investigated in vitro. When murine normal colonic epithelial cell tine MCE301 cells were stimulated with bupleuran 2llc, the contents of granulocyte colony-stimulating factor (G-CSF) in the conditioned medium were significantly increased in dose- and time-dependent manners. The enhanced G-CSF gene transcription in MCE301 cells by the stimulation of bupleuran 2llc was observed by RT-PCR. The enhanced G-CSF secretion by bupteuran 2llc was also observed in C3H/HeJ mice derived primary cultured colonic epithelial, cells. Bupleuran 2llc was digested with endo-(1 -> 4)-alpha-D-polygalacturonase, and the resulting bupleuran 2llc/PG-1 (ramified region) showed potent G-CSF secretion enhancing activity. The activity of bupteuran 2;;c/PG-1 disappeared after the removal of arabinosyl residues from bupleuran 2llc/PG-1 by endo-(1 -> 5)-alpha-L-arabinanase digestion. These results suggest that the ramified region (bupteuran 2llc/PG-1) is the active site for the G-CSF secretion enhancing activity of bupleuran 2llc, and the arabinan moiety of bupteuran 2llc/PG-1 plays an important rote in expression of the activity. (c) 2008 Elsevier B.V. All rights reserved.