Polysaccharides derived from Yamoa™ (Funtumia elastica) prime γδ T cells in vitro and enhance innate immune responses in vivo

Yamoa (TM) (ground bark of Funtumia elastica tree) is marketed and sold as a dietary supplement with anecdotal therapeutic effects in the treatment of asthma and hay fever. We determined that Yamoa (TM) and Yamoa (TM)-derived polysaccharides affected innate immunity, in part, by priming gamma delta T cells. Gene expression patterns in purified bovine gamma delta T cells and monocytes induced by Yamoa (TM) were similar to those induced by ultrapure lipopolysaccharide (uLPS). In the presence of accessory cells, Yamoa (TM) had priming effects that were similar to those of LPS on bovine and murine gamma delta T cells, but much more potent than LPS on human gamma delta T cells. The bioactive component of Yamoa (TM) was delineated to a complex polysaccharide fraction (Yam-I). Intraperitoneal injection of Yamoa (TM) and Yam-I in mice induced rapid increases in peritoneal neutrophils directed by changes in chemokine expression. In support of a unique agonist found in Yam-I, similar peritonitis responses were also observed in TLR4- and MyD88-deficient mice. Therapeutic treatment with Yam-I resulted in decreased bacterial counts in feces from mice with Salmonella enterica serotype typhimurium (ST)-induced enterocolitis. This characterization of the immune stimulatory properties of polysaccharides derived from Yamoa (TM) suggests mechanisms for the anecdotal positive effects of its ingestion and that these polysaccharides show potential for application in innate protection from disease. (C) 2009 Elsevier B.V. All rights reserved.