Biphasic immunomodulatory effects of ionized biosilica water on the antigen-presenting capability of mouse dendritic cells

ABSTRACT

Biosilica is a silica-based substance derived from the cell walls (frustules) of diatoms and has various biological activities. Recently, research into biosilica’s biological functions are underway, but little has been reported on the effects of biosilica on immune cells. In this study, we investigated the effect of ionized biosilica water (iBW) on dendritic cells (DCs), which play crucial roles as antigen (Ag)-presenting cells. Treatment with iBW increased the expression of immune response-related markers, closely connected to the maturation of DCs, and the production of tumor necrosis factor-alpha. In addition, iBW-treated DCs (iBW-DCs) had a lower uptake of fluorescein isothiocyanate-dextran than that of control DCs. Mixed leukocyte response analysis, used for measuring the Ag-presenting capability of DCs, showed iBW-DCs had a higher capability than that of control DCs. Interestingly, DCs treated with lipopolysaccharide (LPS) and iBW had a lower level of Ag-presenting capability than that of LPS-treated DCs. Taken together, the results indicate that iBW alone can mature DCs, but it decreases the Ag-presenting capability of DCs in the presence of LPS, a representative agent of inflammation. This study may provide valuable information regarding the effect of iBW on immune cells. Further research is needed to investigate how iBW induces the observed biphasic immunomodulatory activity.