Abstract
Purpose :
Sphingolipids are a class of membrane lipids which serve as structural and signaling molecules in both mammalians and fungi. To gain insight into the pathophysiological mechanisms of sphingolipid homeostasis on fungal infection, we performed a multi-omics analysis to obtain the spatial distribution of sphingolipids and transcriptional reprogramming in fungal keratitis.
Methods :
Matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI) was performed in infected human corneal tissues and mouse eyeball tissues of fungal keratitis. Furthermore, time-course RNA-seq was performed at 0, 1, 3, 5 days post infection in fungal keratitis mouse model. Weighted gene co-expression network analysis (WGCNA) was used to reveal the driver gene in fungal keratitis. We further investigated the effect of FTY-720, a modulator of sphingolipid metabolism, on the progression of fungal keratitis.
Results :
Based on the differential metabolites detected by MALDI-MSI, it was observed that sphingolipid metabolism was the most prominent enriched pathway and sphingolipids were downregulated in infected human corneal tissues. The alteration of sphingolipids was validated and the spatial distribution of sphingolipids was obtained in the fungal keratitis mouse model. Specially, it was found that ceramide (p=0.027), ceramide 1-phosphate (p=0.008), sphingosine 1-phosphate (p=0.014) and sphingomyelin (p=0.003) were downregulated in cornea region, while in aqueous humour sphingolipids displayed an opposite trend. To explore the mechanisms of the alteration of sphingolipids, time-course RNA-seq and WGCNA were performed. The analysis results suggested that the degrading enzymes in sphingolipid metabolism drives the progression of fungal keratitis, including Hexa, Arsa, Plpp1, Glb1, Psap and Galc. In addition, restoring the sphingolipid homeostasis by FTY-720 reduced the clinical scores of ocular surface (p=0.001) and relieved the progression of fungal keratitis.
Conclusions :
Our results suggested that disruption of sphingolipid homeostasis enhances the progression of fungal keratitis. Thus, restoring sphingolipid homeostasis is a promising strategy to relieve the progression of fungal keratitis. However, the mechanism of the effect of FTY-720 on sphingolipids has not been elucidated. Further investigation will be needed to discover the best target to restore sphingolipid homeostasis in fungal keratitis.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.