Live 4D monitoring of fungal infection in an ex vivo model of fungal keratitis reveals enhanced efficacy of combined PACK-CXL and natamycin treatment

Fungal keratitis, a major cause of visual impairment globally, has challenged researchers in developing and assessing new treatment methods due to experimental models that fail to accurately replicate deep stromal infection or lack the capacity for tracking fungal growth over time. Researchers have now devised an ex vivo porcine corneal model of Aspergillus fumigatus keratitis that successfully reproduces the deep stromal invasion and allows for continuous, non-destructive monitoring of infection progression.

Through optimizing culture conditions, the research team discovered that reducing nutrient availability significantly enhanced stromal penetration compared to nutrient-rich conditions. By employing a YFP expressing A. fumigatus strain alongside confocal microscopy and three-dimensional image analysis, the researchers were able to accurately quantify fungal burden within individual corneas, tracking the changes in infection patterns longitudinally.

Utilizing this model, the team tested the efficacy of natamycin and photoactivated chromophore for keratitis corneal cross-linking (PACK-CXL), individually and in combination. While both treatments independently significantly limited the growth of fungal burden in untreated corneas, neither consistently reduced pre-existing fungal burden.

However, when combined, natamycin and PACK-CXL treatments proved to be significantly more effective in reducing fungal burden across all treated corneas, outperforming treatments applied individually.

This research establishes a quantitative ex vivo platform for studying invasive A. fumigatus corneal infection, providing valuable insights into the distinctions between treatments that restrict fungal expansion and those that specifically target established fungal burden. The model offers a promising approach for long-term evaluation and optimization of therapeutic interventions for fungal keratitis.