Abstract
Purpose :
Fungal endophthalmitis is a relatively uncommon but serious complication of intraocular surgery or trauma and is often associated with poor prognosis. Its incidence has increased in recent years, particularly in tropical countries, with the main aetiology being filamentous fungi, particularly Aspergillus sp. The purpose of this study was to understand the protein cargo of Extracellular Vesicles (EVs) in a murine model of Aspergillus flavus endophthalmitis.
Methods :
EVs were isolated by differential ultracentrifugation from C57BL/6 mice eyes challenged with A. flavus at 24-72 hours post-infection (p.i). Isolated EVs were characterized by Dynamic Light Scattering (DLS), ExoCet assay, western blot, and cytokine analysis. Mass spectrometry (LC-MS/MS) quantitative analysis was also performed for comparing the protein profile of these EVs with uninfected mice.
Results :
EVs derived from eyes infected with A. flavus ranged from 200-250nm in diameter and the concentration was higher at 24 h p.i. 1.55x1010±554665251, in comparison to EVs from control -1.24x109 (p = 0.001). Western blot analysis confirmed the presence of markers: CD9, CD63, and CD81. In addition, IL-6 was significantly elevated at 72 h p.i in EVs from infected eyes (p=0.02). Proteomic analysis identified 81 differentially expressed proteins, of which 22 were upregulated and 59 were downregulated. Gene Ontology (GO) functional enrichment analysis of differentially upregulated proteins were enriched for transferase activity, protein complex, and tubulin binding such as CDS-diacylglycerol synthase-1(CDS1), fibrillin 1 (FBN1), microtubule-associated protein-4 (MAP4) and calmodulin-dependent protein kinase-2 (CAMK2G). Among the downregulated proteins, S100 calcium-binding protein (S100A9), annexin A1 (ANXA1), lactotransferrin (LTF), and transferrin (TRF) were associated with transport, negative regulation of apoptotic process, and phagocytosis. Additionally, KEGG pathway analysis revealed that differentially upregulated proteins participate in the glucagon signaling while downregulated proteins participate in metabolic and carbon signaling pathways.
Conclusions :
Our findings reveal that EVs cargo in A. flavus endophthalmitis plays a key role in immune regulation and disease progression. Further validation of these proteins can serve as important prognostic markers in patients with fungal endophthalmitis.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.