Induction of innate immune responses by plant-derived procyanidins and polysaccharides

Abstract

Plants contain most of the basic metabolic systems utilized by mammals, but also contain unique structures to interact with self and with non-self biomolecules. It is of little surprise, that many of these plant biomolecules impact mammalian systems. Numerous plant products are used for treating human disease and are critical for the most fundamental aspects of medicine including pain control and cancer therapy. In addition to these drugs, plant products have been used for millennia to improve disease resistance. Our understanding of how these plants activate the innate immune system to fight off infection is tenebrous, with very little understood about receptor-mediated responses. The following studies elaborate upon our current understanding of two common, plant-derived compounds with innate stimulatory activity: procyanidins and polysaccharides. Procyanidins are a class of polyphenols and flavonoids. The research described herein shows that procyanidins directly activated gamma delta T cells to enter a primed state and stabilized select gene transcripts via ERK- and syk-mediated processes. The second class of plant products discussed are polysaccharides from Acai. The innate immune response induced by Acai polysaccharides was mediated by TLR4 and the phagocytic response, possibly mediated by Dectin-1. These studies have improved our understanding of host responses to plant products, which have implications for consumption of both foods and nutritional supplements.