Abstract
Purpose :
Inflammasomes are key molecular regulators that play important roles in inflammation. Their activity is upregulated in infections. The NLRP3 inflammasome is the best characterised but role of this inflammasome in bacterial keratitis is not known. The purpose of the study was to evaluate the outcomes of targeted inhibition of NLRP3 inflammasome in a mouse model of bacterial keratitis.
Methods :
Eyes of 8-10 weeks old female BALB/c mice were infected with strains of Pseudomonas aeruginosa (6294, 6206 and ATCC 19660) or strains of Staphylococcus aureus (31 and 38). 10µL of MCC950 (NLRP3 inflammasome inhibitor) or sterile saline was topically applied twice a day on the infected eye. Ocular grading was performed using a slit lamp. Eyes were collected after 24 and 72 hours post infection to enumerate viable bacterial counts, and to perform cytokine assay to determine the levels of IL-1β.
Results :
BALB/c mice infected with P. aeruginosa 6294 at 24 hours showed a significant lowering (p<0.01) of the clinical response to infection (clinical score 1 ± 0.75 vs. 3 ± 0.75). In BALB/c mice infected with P. aeruginosa 6294 the concentration of IL-1β was significantly reduced (p<0.05) after 3 days compared to 24 hrs treated animals. In contrast, IL-1β levels produced during infection with the cytotoxic P. aeruginosa strains (6206 and ATCC 19660) were elevated in animals treated with MCC950. Levels of IL-1β remain unchanged in BALB/c mice infected with Staphylococcus aureus 31 and 38. Viable bacterial counts remained unchanged with MCC950 treatment and higher bacterial load was observed after 3 days of infection compared to 24 hrs.
Conclusions :
The NLRP3 inflammasome may play an important role by the production of active IL-1β in invasive Pseudomonas keratitis.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.