Introduction: Bacterial biofilms may be implicated in the pathogenesis of chronic rhinosinusitis. Nitric oxide (NO) is a gaseous immunomodulator with a short half-life, complicating achievement of therapeutic concentrations. We have previously shown potent, sustained antibacterial activity of a novel microparticle-based NO delivery platform (SNO-MP). In this study, we explore the antibiofilm activity of SNO-MP and hypothesize that SNO-MP harbors minimal cytotoxicity.
Methods: Patient-derived and reference strains of methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa (PA) biofilms were treated with 10 mg/mL of SNO-MP for 6 hours. Biofilm viability was quantified using confocal laser scanning microscopy and live/dead staining. To evaluate SNO-MP toxicity, patient-derived sinonasal tissue explants were dissociated and grown in submerged culture. Serial dilutions of SNO-MP were applied to the cultures over 5 days and cytotoxicity measured using a lactate dehydrogenase (LDH) assay. All experiments were repeated in triplicate. Statistical analysis was performed with PRISM.
Results: SNO-MP induced a 43.8% and 58.4% reduction in biofilm viability relative to untreated controls in the MRSA 6524 (patient-derived) and MRSA 25923 (reference) strains (p < 0.0001 and p=0.0002, respectively). SNO-MP produced a similar 43.6% and a 56.4% reduction in biofilm viability in the PA 2 (patient-derived) and PA 15692 (reference) strains, respectively (p < 0.0001 for both strains). There was no difference in cytotoxicity of the explant tissues on LDH assay when comparing SNO-MP (2.5–10 mg/mL) and the negative control.
Conclusions: SNO-MP demonstrates potent antibiofilm effect against MRSA and PA without inducing cellular toxicity.