Immunomodulatory Effects of Yeast Cell Wall Compounds on mouse BMDM. Mus musculus

Since few years, yeast cell wall components and especially beta-glucans (BG) have been identified as potential stimulators of the innate immune system in murine and human species. A large screening of crude and BG-enriched components from Saccharomyces cerevisiae has been performed on murine macrophages. A priming effect with bacterial ligands was revealed in terms of pro-inflammatory cytokines release. To further characterize the responsiveness of bone marrow derived-macrophages which express high levels of dectin-1, the major receptor of BG, transcriptional analysis would provide more hypotheses about the genes and signaling pathways triggered by yeast cell wall compounds in macrophages. Gene expression profiling was performed in murine BMDM pretreated with a set of three BG-containing cell wall compounds and then stimulated with LPS. Conditions with BG-enriched pretreatment clustered together in contrast to the crude compound and mock pretreatment conditions that remained separated whatever the time point analyzed, with a greater number of differentially-expressed genes following the crude compound treatment compared to BG-enriched pretreatment. BG-enriched pretreatment induced a specific set of genes in mouse macrophages, involving the PI3K/AKT signaling pathway. Among them, the two main upregulated genes by BG-enriched priming condition were considered for further analysis and their associated-protein production were consistently increased in BMDM pretreated with BG-enriched compound. Microarray results were confirmed using RT-qPCR on a different set of samples. Overall design: Gene expression was measured in murine BMDM pretreated with ScCW (A), BG65 (C) and BG75 (D), or mock controls for 8 h, and further stimulated with LPS for 4 and 8 h. Four independent experiments were performed at each time using 4 individuals for each experiment.