Myopia or nearsightedness, where light focuses in front of the retina making distant objects appear blurry, is the most common refractive vision condition. Though there appears to be both genetic and environmental factors that influence the occurrence and development of myopia, the precise mechanism remains unknown. The aqueous humor (AH) is a transparent fluid that fills the anterior and posterior chamber of the eye and plays several important functions in maintaining the health of the eye. Recent studies have suggested that changes in protein levels in AH is associated with the development of several eye diseases. Thus, there is a gaining interest in studying the composition of AH in relation to the development of disease and possible clinical interventions. Changes in proteins and miRNAs in exosomes derived from the AH have been reported in ophthalmic diseases. In this study the research group aimed to analyse the exosomal protein profile of the AH from myopia patients. Exosomes were isolated from the AH, and the researchers compared the individual exosomal protein profiles from 9 high myopia patients with 9 control patients by using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and PEAKS Studio 7.5 for further analysis. They identified 35 peptides that were significantly increased in myopia patients when compared to the control group, suggesting that myopia patients secreted more exosomal proteins to the AH. Of these peptides, 8 were identified belonging to known proteins. Among these, transthyretin (TTR) and hemopexin (HPX) were identified as myopia specific exosomal proteins. Further studies into the role of TTR and HPX in the development of myopia may provide insight for the diagnosis, clinical treatment and prognosis of myopia. 

How was PEAKS used?

Exosomal proteins were extracted and digested by trypsin and analysed with LC-MS/MS. The raw MS data files were search against a Uniprot Human database using PEAKS Studio 7.5 with a precursor and fragment mass tolerance of 20 ppm and 0.8 Da respectively. Spectral counts obtained from each peptide were normalised to the total spectral counts recorded for all peptides in sample.

Tsai CY, Chen CT, Lin CH, Liao CC, Hua K, Hsu CH, Chen CF. Proteomic analysis of Exosomes derived from the Aqueous Humor of Myopia Patients. Int J Med Sci. 2021 Mar 10;18(9):2023-2029. doi: 10.7150/ijms.51735. PMID: 33850473; PMCID: PMC8040407.

Abstract

Objectives: Myopia is the most common refractive vision disorder. In recent years, several studies have suggested that the alteration of the exosomal protein levels in the aqueous humor (AH) is associated with the development of several eye diseases. Therefore, we aimed to explore the exosomal protein profile of the AH from myopia patients.

Methods: Exosomes were isolated from the AH. The quality, concentration, and size distribution of exosomes for each patient were measured using nanoparticle tracking analysis system. Then, the exosomal proteins were purified and digested by trypsin for liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis.

Results: There was no significant difference observed between the myopia and control when comparing the concentration and size distribution of exosomes in the AH for each sample. Based on LC-MS/MS analysis, myopia patients had higher and more complex exosomal peptide content. We found two proteins that were common in AH exosomes and eight proteins that were highly expressed in the myopia group.

Conclusions: Our results provide pioneering findings for the exploration of the exosomal protein profile in myopia development. Further studies may provide significant information for the diagnosis, clinical treatment, and prognosis of myopia.