Abstract:Saccharomyces cerevisiae, which has vegetative yeast state and spore state under different nutrient conditions, is an important probiotics for human beings and animals. In order to investigate the effect of yeast spores on immune system, the response mechanism of macrophages to yeast spores was preliminarily explored. By comparing the endocytic efficiency of macrophages on vegetative yeasts and wild type spores, it was found that the endocytosis of macrophage to wild type spores was more efficient. Syk or PI3K inhibitor inhibition experiments revealed that the endocytosis of wild type yeast spores and vegetative yeasts were both dependent on the Syk pathway. The endocytosis of wild type yeast spores was more dependent on the PI3K pathway, indicating that the endocytosis of yeast spore and vegetative yeasts was both receptor mediated phagocytosis, however, their phagocytosis pathways were different. High salt and protease treatment experiments demonstrated that the ligands of wild type spores were tightly bound to the spore wall, and the ligands were not protein. Sugar inhibitors competition experiments showed that the macrophages phagocytosis of vegetative yeast, not wild type spores, was inhibited by glucan. The spore phagocytosis of wild-type spores and mutants further showed that the phagocytosis of wild type spores was related to the structure of dityrosine layer. This study demonstrated that the signaling pathway and ligand molecules related to phagocytosis of wild type yeast spores were different from those of vegetative yeasts, which could be regarded as a theoretical reference for the follow-up immune application of Saccharomyces cerevisiae.
