Background/Aim: Acid-electrolyzed functional water (FW) is an efficient bactericide and gargling with FW might be an effective method of oral care. We investigated the possible use of FW as a mouth wash by an in vitro study. Materials and Methods: The bactericidal effect of FW against different species of bacteria (Staphylococcus aureus, Streptococcus pneumonia, Pseudomonas aeruginosa, and Candida albicans) was evaluated using the numbers of colony-forming units (CFU). The experiment was conducted using PBS, LISTERINE, and ConCool F (undiluted, and the optimal concentration indicated). To investigate the bactericidal mechanism of FW, the activity of superoxide dismutase (SOD), an indicator of oxidative action, was measured in S. aureus. FW was diluted with purified water to concentrations of 10, 30, 50, and 70%. The numbers of CFU were measured for each concentration. XTT assays were performed using HSC-3 and HeLa cells, to examine the viability of the cells following treatment with FW. The same experiment was conducted with PBS, LISTERINE, and undiluted ConCool F. Results: No bacteria treated with FW formed colonies. SOD activity peaked at a 50% concentration of FW and was more than twice that of the control. A significant decrease in the number of CFU was observed following 50% treatment. Since the peaks of the SOD activity and the starting concentrations of the bactericidal effects coincided, the bactericidal effect of FW might be related to its oxidative effects. Bacteria treated with FW had the same survival rate as the other mouth washes. Conclusion: FW might be clinically applicable as a mouth wash.

Proteasome inhibitor MG132 was shown to enhance the secretion of interleukin 8 (IL-8) by various cells. The enhancement is regulated by the transcription factor activator protein-1 (AP-1) at the transcriptional level. AP-1 is a dimer formed by AP-1 family proteins. The purpose of the present study was to explore the combinations of the AP-1 family proteins that contribute to MG132-driven IL-8 secretion. Oral squamous cell carcinoma-derived cell lines, Ca9-22 and HSC3, were used to demonstrate their response to MG132. IL-8 secretion was augmented by MG132 in both cell lines. c-Jun expression was detected in both the cell lines, whereas c-Fos expression was detected only in the HSC3. The influence of MG132 stimulation on c-Jun and c-Fos expression was further examined by western blot analysis. c-Jun expression was increased by MG132 stimulation, whereas c-Fos expression was not detected even after MG132 stimulation. As JunB is reported to inhibit the transcriptional activity of the AP-1 complex, we speculated that the c-Jun homodimer should contribute to IL-8 enhancement. Expression vectors encoding wild type and c-Jun mutants, M17 and M22-23, respectively, were constructed and transfected into the Ca9-22 cells. In contrast to our expectations, MG132-induced IL-8 secretion was significantly reduced in all the transfectants suggesting that other c-Jun members might form homodimers with c-Jun and contribute to IL-8 enhancement. Transfection of the cells with c-Jun or JunB small hairpin RNA (shRNA) reduced IL-8 secretion up to 50% and 65% of the control shRNA transfectant. Furthermore, cotransfection of both shRNA almost completely inhibited the IL-8 secretion. These results indicate that JunB not only inhibits but also enhances the transcription of c-Jun targets in combination with c-Jun.

The aim of this study was to examine the acid-electrolyzed functional water (FW)-mediated cytokine release in an oral squamous cell carcinoma-derived cell line (OSCC) following treatment with FW. FW is generated by the electrolysis of a sodium chloride solution and accelerate the burn wound healing. To elucidate the underlying mechanisms, the cytokine/chemokine secretion profile of HSC3 cells was examined using a cytokine array. FW treatment significantly induced interleukin (IL)-1α secretion, which was confirmed by enzyme-linked immunosorbent assay. Subsequently, the HSC3 cells were pre-treated with cycloheximide (CHX) for 1 h prior to FW stimulation to determine whether the augmented IL-1α secretion was due to enhanced protein synthesis. CHX pre-treatment did not affect IL-1α secretion suggesting that the secreted IL-1α might have been derived from intracellular storage sites. The amount of IL-1α in the cell lysate of the FW-treated HSC3 cells was significantly lower than that of the non-treated cells. Immunofluorescence staining using a polyclonal antibody against full-length IL-1α revealed a drastic reduction in IL-1α inside the FW- treated cells. IL-1α is synthesized in its precursor form (pIL-1α) and cleaved to produce pro-piece and mature IL-1α (ppIL-1α and mIL-1α) inside the cells. In the present study, only pIL-1α was detected within the HSC3 cells in its resting state. However, FW stimulation resulted in the release of the 33 kDa and two other smaller forms (about 19 kDa) of the protein. These results indicates that FW treatment induces IL-1α secretion, a typical alarmin, from the intracellular storage in OSCC cells.

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