Pseudomonas aeruginosa, a nosocomial pathogen, has strong biofilm capabilities, representing the main source of infection in the human body. Repurposing existing drugs has been explored as an alternative strategy to combat emerging antibiotic-resistant pathogens. Fingolimod hydrochloride (FTY720), an immunomodulatory drug for multiple sclerosis, has shown promising antimicrobial effects against some ESKAPE pathogens. Therefore, the effects of FTY720 on the biofilm capabilities of Pseudomonas aeruginosa were investigated in this study. It was determined that FTY720 inhibited the growth of P. aeruginosa PAO1 at 100 µM. The significant reduction in PAO1 cell viability was observed to be dose-dependent. Additional cytotoxicity analysis on human cell lines showed that FTY720 significantly reduced viabilities at sub-inhibitory concentrations of 25–50 µM. Microtiter assays and confocal analysis confirmed reductions in biofilm mass and thickness and the cell survivability ratio in the presence of FTY720. Similarly, virulence production and biofilm-related gene expression (rhlA, rhlB, pilA, pilI, fliC, fliD and algR) were determined. The results demonstrate that pigment production was affected and quantitative real-time PCR analysis showed a variable degree of reduced gene expression in response to FTY720 at 12.5–50 µM. These findings suggest that FTY720 could be repurposed as an alternative antibiofilm agent against Pseudomonas aeruginosa.

Human gingival fibroblasts (HGnFs) play crucial roles in periodontal wound healing. This in vitro study examined the impact of varying concentrations of topical oxygen fluid (blue^®m) on HGnF morphology, viability, proliferation, oxidative stress and pro-inflammatory cytokine production. The attempt was to underscore the potential of blue^®m as a less cytotoxic alternative to chlorhexidine in the context of tissue-regeneration improvement. Primary HGnF cell cultures were subjected to oxygen fluid (blue^®m) at concentrations of 0.6, 1.2 and 2.4% for a duration of 1 min. The positive control was 0.12% chlorhexidine. Cell morphology as well as actin cytoskeleton were assessed using microscopy and immunofluorescence staining. Cell viability and proliferation were assessed through AlamarBlue and trypan blue assays at 1, 2, 7, 10 and 14 days. Levels of reactive oxygen species (ROS) were quantified using DCFH-DA assay. Pro-inflammatory cytokines (IL-1β, IL-6, TNF-α, MMP-8 and TIMP-1) were assessed through ELISA. HGnF morphology and actin structure were preserved at all oxygen fluid concentrations. Cell viability and proliferation were significantly higher in the 0.6% and 1.2% groups than in the control and chlorhexidine groups (p ≤ 0.05). ROS levels were low at 0.6% and 1.2%, but increased at 2.4% and with chlorhexidine (p ≤ 0.05). Oxygen treatment reduced IL-1β, IL-6, TNF-α and TIMP-1 expression, while MMP-8 levels increased. Chlorhexidine significantly upregulated the expression of all proinflammatory cytokines (p ≤ 0.01). Oxygen fluid (blue^®m) therapy improves the viability and proliferation of gingival fibroblasts and offers anti-inflammatory and preliminary antioxidative effects at the cellular level, especially at lower concentrations (0.6% and 1.2%), indicating potential application in periodontal wound management, subject to clinical validation.