Immune regulatory effects of beer yeast and yeast extract yeast cell wall

      Yeast and yeast fermentation products exhibit complex and diverse mechanisms of action in immune regulation due to their abundant bioactive components. Its core active substances, such as β - glucan, mannan, fermentation derived peptides, organic acids, etc., can interact with the host immune system through multiple targets and pathways to achieve precise regulation of innate and adaptive immunity. ​

      β - glucan, as a hallmark component of yeast cell wall, can bind to the surface of immune cells through pattern recognition receptors such as Dectin-1 and TLR2, triggering intracellular signaling pathways. This process can activate antigen-presenting cells such as macrophages and dendritic cells, promote their phagocytic activity and secretion of cytokines (such as IL-1 β, TNF - α, IL-6), thereby initiating innate immune response. At the same time, β - glucan can induce dendritic cell maturation, enhance their ability to present antigens to T cells, promote Th1 type immune response, promote the release of cytokines such as IFN - γ, and strengthen cellular immune function.
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      Mannan mainly exerts its effects by regulating intestinal mucosal immunity. Its molecular structure can simulate the mannose receptor ligand on the surface of intestinal pathogens, competitively bind to receptors on the surface of intestinal mucosal epithelial cells and immune cells, and inhibit the adhesion and colonization of pathogenic bacteria. More importantly, mannan can stimulate plasma cells in the intestinal mucosal lamina propria to secrete secretory IgA (sIgA). sIgA can encapsulate pathogens to form immune complexes, preventing them from penetrating the mucosal barrier. At the same time, it activates the complement system, synergistically clearing foreign substances, and building the first line of defense for mucosal immunity.
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      Small molecule peptides in yeast fermentation products, along with organic acids such as lactic acid and acetic acid, also participate in immune regulation. Short peptides can directly act on lymphocytes, promoting T cell proliferation and B cell antibody production; Organic acids indirectly improve the balance of gut microbiota by lowering the pH value of the intestine, inhibiting the proliferation of harmful bacteria, and maintaining a healthy gut microbiota is key to maintaining immune homeostasis. Their metabolites, short chain fatty acids (such as butyric acid), can further regulate immune cell differentiation, promote the production of regulatory T cells (Tregs), and inhibit excessive inflammatory responses.

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      In the context of livestock and poultry farming, this immune regulatory effect has been fully validated: broiler chickens supplemented with yeast cell wall extract showed a significant increase in the proportion of CD4 ⁺ and CD8 ⁺ T cells in their peripheral blood, and the antibody titer after immunization with avian influenza vaccine increased by 20% -30%; Supplementing yeast fermented products in the diet of laying hens increases the sIgA content in the intestinal mucosa and reduces the Salmonella infection rate by more than 40%. These data confirm that yeast and yeast fermentation products can enhance the body's ability to resist infections through multi-level immune regulation, while avoiding tissue damage caused by immune hyperactivity, providing a reliable immunological basis for replacing antibiotics. ​