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Beta Glucan Mechanisms of Action
More than 800 publications have reported that b1,3-glucans, either soluble or particulate, exhibit immunomodulatory properties.
Studies have demonstrated that b1,3-glucan has strong immunostimulating activity in wide variety of other species, including earthworms, shrimps, fish, chicken, rats, rabbits, guinea pigs,
sheep, pigs, cattle and humans. Based on these results it has been concluded that b1,3-glucan represents a type of immunostimulant that is active across the evolutionary spectrum, likely
representing an evolutionarily conserved innate immune response directed against fungal pathogens.
The oral protective effect of yeast b1,3-glucan appears to be mediated through
intestinal mucosal cell interactions leading to the stimulation of cytokine production. Focus has bben on three important cytokines, IL-2, IFN-? and TNF-a. All of these cytokines play an
important role not only in physiological processes, but also in bioregulation of host defense reactions. IL-2 is a cytokine produced by activated CD4 and some CD8 T lymphocytes. In addition
to being the major T cell growth factor, IL-2 also stimulates: growth and differentiation of cytotoxic T cell precursors, NK cells, differentiation of activated human B-lymphocytes and
activation of monocytes. TNF-a is a pleiotropic cytokine secreted primarily by monocytes/macrophages and T lymphocytes, respectively. TNF-a is the principal mediator of natural immunity
against Gram-negative bacteria and a key mediator of inflammatory responses and septic shock.61 IFN-?, sometimes called immune interferon, is produced mainly by T lymphocytes as a result of
antigenic or mitogenic stimulation. The activities of IFN-? are many, including induction of MHC expression, macrophage activation, and effects on the differentiation of lymphocytes.
Evidence of orally administered b1,3-glucan immunomodulatory activity has been demonstrated through effects on the production of three different cytokines, IL-2, IFN-? and TNF-a. The
production of these three cytokines was measured after a 72 hr in vitro incubation of spleen cells isolated from control and b1,3-glucan-administered animals. In all three tested cytokines,
oral administration of ί-glucan resulted in significant increase of the cytokine levels (Figure 1).(re-create the japanese chart on cytokines).
At present we do not fully understand
the mechanisms mediating the effects of orally administered b1,3-glucan. We believe that through specific interactions between the b1,3-glucan active component of b1,3-glucan and b1,3-glucan
receptors on M-cells within Peyers patches in the intestinal mucosa that a systemic signal (cytokines) is elicited by the gut associated lymphatic system that stimulates the innate immune
system components (macrophages, neutrophils, NK cells) to a higher functional level, increasing the first line of host defense mechanisms. The involvement of b1,3-glucan binding by CR3
receptors enhancing the recognition of targets with complement fragments is another possibility. Increased proliferation of myeloid cell precursors in bone marrow and increased homing of
matured myeloid cells into final tissues, described previously as b1,3-glucan-stimulated is most probably also involved. Despite our current lack of knowledge about the precise mechanisms
through which oral b1,3-glucan mediates its protective effects, the data indicating anti-tumor and anti-infective properties of yeast-derived b1,3-glucan presented in numerous scientific
studies suggests that further study is warranted to fully understand the benefits of b1,3-glucans.
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