Physcion alleviates Aspergillus fumigatus keratitis by inhibiting fungal growth and NF-κB-mediated inflammation.

OBJECTIVE

Physcion, a natural anthraquinone, possesses antifungal and anti-inflammatory activities. This study aimed to investigate its antifungal and anti-inflammatory effects in a murine model of Aspergillus fumigatus (AF) keratitis (AFK).

METHODS

The safety of physcion was evaluated using Cell Counting Kit-8 assays, live/dead cell staining and the Draize test. Antifungal activity was assessed by propidium iodide staining, calcofluor white staining, crystal violet biofilm assays and determination of the MIC. Network pharmacology analysis was performed to predict potential therapeutic targets of physcion. Both in vitro and in vivo experiments were conducted using AF spore-infected mouse corneas and RAW264.7 macrophages treated with physcion or phosphate-buffered saline. Inflammatory responses were evaluated by slit-lamp examination, immunofluorescence, real-time quantitative polymerase chain reaction (RT-qPCR) and western blotting (WB), focusing on neutrophil and macrophage recruitment together with the expression of pro-inflammatory proteins and components of the NF-κB signalling pathway.

RESULTS

Physcion effectively inhibited the growth of AF. In vivo, physcion-treated mice exhibited significantly lower clinical scores compared with untreated infected controls. Immunofluorescence analysis revealed markedly decreased infiltration of neutrophils/macrophages in the corneas of physcion-treated mice. RT-qPCR together with WB analyses demonstrated that physcion treatment obviously reduced the phosphorylated NF-κB p65 and phosphorylated IκB, increased IκB expression and suppressed the expression of IL-1β, TNF-α and IL-18 in infected mouse corneas and RAW264.7 cells. Consistently, IF imaging of RAW264.7 cells showed reduced nuclear localization of NF-κB p65 following physcion treatment.

CONCLUSION

Physcion alleviated AFK by inhibiting fungal growth, limiting neutrophil and macrophage recruitment, and suppressing activation of the NF-κB signalling pathway.