Immune Benefits From Mushroom Consumption
Condition: Healthy Humans
Study type: Interventional

Summary: 
      The purpose of this study is to determine whether consuming mushrooms is effective in
      enhancing the function of γδ T cells.
    

Detailed description: 
      A non-therapeutic study is described. This is an intervention study at two levels of mushroom
      intake. The number of subjects and experimental assays are selected as a pilot study to
      generate the dose level and the efficacy. Subjects age 21 to 50 will be recruited and provide
      a baseline blood draw. The mushroom supplementation will occur for 4 weeks at two levels 85 g
      (3 ounces) and 170 g (6 ounces). Immunity changes fairly rapidly; in and early study the
      investigators saw changes in as little as 3 days. Blood is taken again at 4 weeks. Peripheral
      blood mononuclear cells are isolated from the blood and used freshly isolated, or cultured in
      autologous serum for 24 hours or for 10 days. Freshly isolated cells will be used to count γδ
      T cell and NK cells baseline values. After 24 hours of stimulation with a broad based
      mitogen, culture medium is harvested and assayed for cytokines secreted into the culture
      medium as well as NK cell activation and proliferation. Finally, cells are harvested after 10
      days and assayed for γδ T cell activation and proliferation.

      Consumers will benefit from knowing that health benefits can be derived from mushrooms.
      Potentially, this will stimulate mushroom sales and increase the variety of mushrooms
      consumed.

      γδ T cells reside in epithelial linings of the lung, gut and reproductive tract and although
      their number is not precisely known, they are in much greater numbers than the circulating αβ
      T cells. γδ T cells are not activated in the same way as the αβ cells, they are activated
      more like cells of the innate immune system, by recognition of pathogen-associated molecular
      patterns (1,2). Recognition of pathogen-associated molecular patterns is rather non-specific,
      but very effective. For example, prenyl phosphate is a molecule having a pattern that is
      recognized by receptors of the γδ T cells. Interaction of prenyl phosphate with the γδ T cell
      receptor results in γδ T cell proliferation; expression of cell surface activation markers,
      such as cytokine receptors; and lastly, synthesis and secretion of cytokines necessary for
      communicating with other branches of the immune system. The investigators hypothesize that
      consuming mushrooms will result in greater proliferation when stimulated and will also
      enhance their capacity for activation, defined here as cytokine secretion and cell surface
      marker expression.

      A second quality of γδ T cells is their ability to turn off the immune response once it is no
      longer needed. Carding and Egan (3,4) showed that γδ T cells were responsible for killing
      activated macrophages after the pathogen had been eliminated. Knockout mouse models show that
      the elimination of γδ cells promote chronic inflammation, prevent wound healing (5) and may
      increase the risk for cancer (6,7). The magnitude and the importance of the γδ T cell are
      just being realized. By strengthening γδ T cells, the investigators will fight pathogen
      better and resolve inflammation quicker.

      It is our hypothesis that there are certain bioactive components that resemble
      pathogen-associated molecular patterns and interact weakly with the epithelial γδ T cells in
      such a way that they are "primed", but not activated. The bioactive food components do not
      interact with the cells with enough strength to cause an actual response, but, later, when
      the cells do encounter pathogen, they can react quicker and with more intensity if they have
      already been primed. The primary bioactive components in mushrooms that may interact with
      immune cells are polysaccharides and glycoproteins and the two major types of mushroom
      polysaccharides include glucans (both β and α) and heteroglycans. Additionally, mushrooms
      contain another important polysaccharide, chitin. Chitin is composed of
      N-acetyl-d-glucosamine units (8,9). These compounds are some likely candidates, in addition
      to other immuno-modulating compounds such as Vitamin D (10) and B vitamins.

      Mushrooms have been shown to have an impact on immune cells, particularly NK cells (11,12)
      but the γδ T cell has not been studied. The composition of mushroom is well suited to
      interact with the γδ T cell. NK cell activity will be used in this study as a positive
      control although the investigators will use flow cytometry rather than generalized
      non-specific cytolytic activity.

      The investigators know from our previous studies in humans (7,13,14) and from other published
      studies (15,16) that foods such as tea, apples, encapsulated fruits and vegetables contain
      compounds that appear to prime γδ T cells. The investigators hypothesize that bioactive
      compounds in the gut are recognized by intestinal γδ T cells, resulting in a primed cell.
      These cells are not static but migrate in and out of tissues, through the circulation as well
      as lymph nodes (17). Thus, the investigators can measure functional changes in the blood
      borne γδ T cells regardless of whether the bioactive compound is absorbed or not.

      This study will specifically study the shiitake (Lentinus edodes) mushroom. This mushroom has
      been shown in other research to have a variety of health benefits, but few feeding trials,
      and none in healthy humans, has been done (18-20).

      5. Specific Aims:

      The aim is to determine if bioactive compounds in mushroom can enhance the activity of this
      cell type. Because this cell type resides in the epithelial linings and migrates via the
      blood and lymph system, the investigators can measure functional changes in this cell
      regardless of whether bioactive compounds are absorbed or not. It is often describe as the
      first line of defense.
    

Intervention name(s): 3 ounces of mushrooms; 6 ounces of mushrooms
Intervention type(s): Dietary Supplement; Dietary Supplement
Intervention description(s): 3 ounces of mushrooms consumed daily for 4 weeks; 6 ounces of mushrooms consumed daily for 4 weeks
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Basic Science
Keywords: gamma delta T cell; proliferation