Bone marrow is soft and sponge-like material found inside bones that contains hematopoietic cells responsible for development and proliferation of peripheral blood cells. The monocytes proliferation generated in the bone marrow and the differentiation of this cells in macrophages plays a key role in the immune response. In this context, the research for drugs that enhance the innate immune response is needed to restore the homeostasis and the immune response. Kojic Acid (KA) is a secondary metabolite synthesized by some species of fungi from Aspergillus genera and has several applications (food additive, cosmetics, antitumor agent and macrophage activator). Thus, the aim of this study is to evaluate the immunomodulatory effects of kojic acid (KA) in the bone marrow cells of mice. These cells were obtained by flushing femurs, and maintained in cultures treated with KA at the concentration of 100 μg/mL for 24-96 hours of culture. It was observed by optical microscopy that KA promoted increased cell adhesion, spreading ability and high number of cytoplasmatic projections and vacuoles in cytoplasm in the mononuclear cells from bone marrow treated with AK. To confirm these results, Akt signaling pathway was analyzed by western blot. KA seems to be able to activate the Akt signaling pathway that have a critical regulatory role in cellular development and differentiation. In addition, we detected by cytometer analysis, increase in the F4/80 and in the CD11b expression, and decrease in CD11c when cells were treated for 96 hours, showing that KA induce the differentiation of bone marrow cells in macrophages, but not in dendritic cells. The Analysis of the microbicidal response revealed that KA also potentiated phagocytosis and increased the production superoxide anion, But not promoted increases of nitric oxide production. Furthermore, no cytotoxic effects were observed in cells treated with KA when compared to the untreated bone marrow cells. Thus, KA acts as an immunomodulatory and is able to induce bone marrow monocyte-macrophage differentiation process.
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