Proteomic analysis of Exosomes derived from the Aqueous Humor of Myopia Patients

Proteomics Analyses of Small Extracellular Vesicles of Aqueous Humor: Identification and Validation of GAS6 and SPP1 as Glaucoma Markers

Cataracts and glaucoma account for a high percentage of vision loss and blindness worldwide. Small extracellular vesicles (sEVs) are released into different body fluids, including the eye's aqueous humor. Information about their proteome content and characterization in ocular pathologies is not yet well established. In this study, aqueous humor sEVs from healthy individuals, cataracts, and glaucoma patients were studied, and their specific protein profiles were characterized. Moreover, the potential of identified proteins as diagnostic glaucoma biomarkers was evaluated. The protein content of sEVs from patients' aqueous humor with cataracts and glaucoma compared to healthy individuals was analyzed by quantitative proteomics. Validation was performed by western blot (WB) and ELISA. A total of 828 peptides and 192 proteins were identified and quantified. After data analysis with the R program, 8 significantly dysregulated proteins from aqueous humor sEVs in cataracts and 16 in glaucoma showed an expression ratio ≥ 1.5. By WB and ELISA using directly aqueous humor samples, the dysregulation of 9 proteins was mostly confirmed. Importantly, GAS6 and SPP1 showed high diagnostic ability of glaucoma, which in combination allowed for discriminating glaucoma patients from control individuals with an area under the curve of 76.1% and a sensitivity of 65.6% and a specificity of 87.7%.

Extracellular vesicle biomarkers in ocular fluids associated with ophthalmic diseases

Extracellular vesicles (EVs) are released as highly stable lipid bilayer particles carrying proteins, lipids, glycans and miRNAs. The contents of EVs vary based on the cellular origin, biogenesis route and the functional state of the cell suggesting certain diseased conditions. A growing body of evidence show that EVs carry important molecules implicated in the development and progression of ophthalmic diseases. EVs associated with ophthalmic diseases are mainly carried by one of the three ocular biofluids which include tears, aqueous humor and vitreous humor. This review summarizes the list of EV derived biomarkers identified thus far in ocular fluids for ophthalmic disease diagnosis. Further, the methods used for sample collection, sample volume and the sample numbers used in these studies have been highlighted. Emphasis has been given to describe the EV isolation and the characterization methods used, EV size profiled and the EV concentrations analyzed by these studies, thus providing a roadmap for future EV biomarker studies in ocular fluids.

Aqueous humor protein markers in myopia: a review

PURPOSE

Myopia is one of the most common forms of refractive error. Most myopia manifests itself as a relative growth of the eye axis, resulting in a state in which light is projected in front of the retina after being refracted by the refractive system of the eyeball. So far, the specific pathogenesis of myopia is still not well explained, through the results of animal experiments, researchers have proposed various possible scenarios, but all these are based on animal models, and there may still be a certain gap with the mechanism of true myopia in humans. The most readily available in clinical work is aqueous humor obtained during cataract surgery, for which we reviewed these studies of aqueous humor samples from myopic patients.

METHODS

A systematic literature search was done on PubMed using key words including "myopia," "aqueous humor," and "protein."

RESULTS

The results of existing aqueous humor studies have shown that the difference in substances in the aqueous humor of myopia is related to the degradation of the scleral matrix, chronic inflammation of the eye, pro-fibrosis, blood vessel production, and inhibition. There may be more than one reason associated with myopia progression.

CONCLUSION

The specific mechanism of myopia has not been fully elucidated. Therefore, the means of preventing and treating myopia should focus on inhibiting the degradation of the scleral matrix, promoting the proliferation of scleral collagen fibers, and alleviating chronic inflammation of the eyes. Further research into myopic aqueous humor may provide us with new insights.

Proteomic profiling of aqueous humor-derived exosomes in Vogt-Koyanagi-Harada disease and Behcet's uveitis

Vogt-Koyanagi-Harada (VKH) disease and Behcet's uveitis (BU) are the two major vision-threatening uveitis entities. This study performed the first label-free quantitative proteomics on aqueous humor-derived exosomes from 84 patients with VKH or BU to determine their potential roles. Sixty-five differentially expressed proteins (DEPs) and 40 DEPs were detected in the VKH and BU groups, respectively. GO and KEGG analysis showed that DEPs were mainly enriched in the complement-related pathways. The complement C1q subcomponent subunit B (C1QB) was identified as a key exosomal protein, and its expression was significantly increased by western blotting in both diseases. Additionally, the integrated analysis based on the published scRNA-seq data showed that C1QB-containing exosomes were mainly produced by mononuclear macrophages in the anterior segment tissue. Overall, our proteomic profiling highlights that complement-related pathways may be actively involved in the pathogenesis of these two diseases. These pathways may also serve as treatment targets for both diseases.

Insights into myopic choroidal neovascularization based on quantitative proteomics analysis of the aqueous humor

BACKGROUND

Previous studies on the biomarkers of pathologic myopia choroidal neovascularization (pmCNV) development merely detected limited types of proteins and provide a meagre illustration of the underlying pathways. Hence, a landscape of protein changes in the aqueous humor (AH) of pmCNV patients is lacking. Here, to explore the potential mechanisms and biomarkers of pmCNV, we analyzed the clinical data and protein profile among atrophic (A) lesions, tractional lesions (T) and neovascular (N) lesions in myopic patients based on the ATN grading system for myopic maculopathy (MM).

RESULTS

After investigating demographic data of our patients, a correlation was found between A and N lesions (R = 0.5753, P < 0.0001). Accordingly, groups were divided into patients without MM, patients with myopic atrophic maculopathy (MAM), and patients with pmCNV (N2a lesion). In proteomics analysis, the increased protein level of GFAP and complement-associated molecules in AH samples of the 3 groups also indicated that MAM and pmCNV shared similar characteristics. The GO enrichment and KEGG pathway analysis were performed, which mapped that differential expressed proteins mainly engaged in JAK-STAT pathway between the pmCNV group and two controls. Furthermore, we identified several potential biomarkers for pmCNV, including FCN3, GFAP, EGFR, SFRP3, PPP2R1A, SLIT2, and CD248.

CONCLUSIONS

Atrophic lesions under pathologic myopic conditions demonstrated similarities to neovascularization development. Potential biomarkers including GFAP were associated with the pathogenesis of pmCNV. In summary, our study provides new insights for further research on pmCNV development.

Effects of inflammation on myopia: evidence and potential mechanisms

As the most common type of refractive error, myopia has become one of the leading causes of visual impairment. With the increasing prevalence of myopia, there is a growing need to better understand the factors involved in its development. Inflammation, one of the most fundamental pathophysiological processes in humans, is a rapid response triggered by harmful stimuli and conditions. Although controlled inflammatory responses are necessary, over-activated inflammation is the common soil for many diseases. The impact of inflammation on myopia has received rising attention in recent years. Elevated inflammation may contribute to myopia progression either directly or indirectly by inducing scleral remodeling, and myopia development may also increase ocular inflammation. This article provides a comprehensive review of the interplay between inflammation and myopia and the potential biological mechanisms, which may present new targets for understanding the pathology of myopia and developing myopia therapies.

Vascular endothelial cell-derived exosomal miR-1246 facilitates posterior capsule opacification development by targeting GSK-3β in diabetes mellitus

Posterior capsule opacification (PCO) is a serious complication after cataract surgery. Diabetes could increase the occurrence of PCO, but the mechanism is still unclear. The purpose of this study is to investigate the role of small extracellular vesicles (sEVs) derived from diabetic aqueous humor in PCO process. Intraoperatively-derived aqueous humor sEVs from patients with diabetic related cataract (DRC) promoted the epithelial-mesenchymal transition (EMT) and metastasis of human lens epithelial cells (LECs). Via mouse PCO surgical model and DiI labeled fluorescence detection of sEVs, the sEVs derived from vascular endothelium were discovered directly contacting with LECs. Furthermore, we demonstrated that high-glucose-cultured human umbilical vein endothelial cells (HUVEC) -derived sEVs facilitated EMT process of HLE-B3 using co-culture model in vitro. MiRNA-seq data and GEO datasets analysis revealed that miR-1246 was essential in EMT process with diabetes. The miR-1246 was highly expressed in diabetic aqueous humor sEVs and high-glucose-treated vascular-endothelial-cell-derived sEVs. Moreover, miR-1246 promoted the metastasis and EMT process of HLE-B3 cells by directly targeting GSK-3β. Inhibiting miR-1246 could negatively regulated EMT. This finding might serve as a potential therapy for diabetic PCO.

Proteomic characterization of aqueous humor in corneal endothelial decompensation after penetrating keratoplasty

Corneal endothelial decompensation (CED) is the major cause of the long-term graft failure, but the underlying mechanisms remain unclear. The purpose of this study was to characterize the proteomic profile in CED aqueous humor (AH) after penetrating keratoplasty (PKP). We collected AH samples (n = 6/group) from CED patients underwent PKP and cataract patients, respectively. The label-free quantitative proteomic analysis was performed to identify the differentially-expressed proteins (DEPs). The biological functions of DEPs were evaluated using Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genome (KEGG) analysis. The protein-protein interaction (PPI) network construction was employed to distinguish the hub proteins of DEPs, and the selected proteins were validated by parallel reaction monitoring (PRM). The human peripheral blood mononuclear cells (PBMCs) were adopted to investigate the effect of biglycan (BGN) on inflammatory response, and the subsequent outcomes of inflammation on human corneal endothelial cells (HCECs). A total of 174 DEPs were identified in CED AH of patients underwent PKP, including 102 up-regulated proteins and 72 down-regulated proteins. Bioinformatics analysis revealed the significant enrichment of cytokine-mediated signaling pathway and extracellular matrix (ECM) organization in the up-regulated proteins, as well as the alterations of cellular components, including the increase of collagen and complement component C1 complex, and reduction in extracellular exosomes. A hub protein cluster of 15 proteins was determined by Molecular Complex Detection (MCODE), including FN1, BGN, COMP, COL11A1, COLA3A1, and COL1A1. Moreover, BGN promoted pro-inflammatory cytokine (such as TNF-α, IL-1β and IL-6) production in PBMCs through NF-κB signaling pathway, which subsequently resulted in HCECs death. These findings provided a systemic protein profile of AH in CED patients after corneal transplantation, with the alterations implicated in cytokine-mediated signaling, ECM, complement system, and exsomes. The identified proteins and signaling pathways probably paved the novel insight into understanding the pathogenesis of the disease.

Extracellular Vesicles as reconfigurable therapeutics for eye diseases: Promises and hurdles

A large number of people worldwide suffer from visual impairment. However, most available therapies rely on impeding the development of a particular eye disorder. Therefore, there is an increasing demand for effective alternative treatments, specifically regenerative therapies. Extracellular vesicles, including exosomes, ectosomes, or microvesicles, are released by cells and play a potential role in regeneration. Following an introduction to EV biogenesis and isolation methods, this integrative review provides an overview of our current knowledge about EVs as a communication paradigm in the eye. Then, we focused on the therapeutic applications of EVs derived from conditioned medium, biological fluid, or tissue and highlighted some recent developments in strategies to boost the innate therapeutic potential of EVs by loading various kinds of drugs or being engineered at the level of producing cells or EVs. Challenges faced in the development of safe and effective translation of EV-based therapy into clinical settings for eye diseases are also discussed to pave the road toward reaching feasible regenerative therapies required for eye-related complications.

Phenotypic and functional characterization of aqueous humor derived extracellular vesicles

Extracellular vesicles (EVs) are double membrane vesicles, abundant in all biological fluids. However, the characterization of EVs in aqueous humor (AH) is still limited. The aim of the present work was to characterize EVs isolated from AH (AH-EVs) in terms of surface markers of cellular origin and functional properties. We obtained AHs from patients with cataract undergoing surgical phacoemulsification and insertion of intraocular lenses (n = 10). Nanoparticle tracking analysis, electron microscopy, super resolution microscopy and bead-based cytofluorimetry were used to characterize EVs from AH. Subsequently, we investigated the effects of AH-EVs on viability, proliferation and wound healing of human immortalized keratinocyte (HaCaT) cells in vitro in comparison with the effect of mesenchymal stromal cell-EVs (MSC-EVs). AH-EVs had a mean size of around 100 nm and expressed the classical tetraspanins (CD9, CD63 and CD81). Super resolution microscopy revealed co-expression of CD9, CD63 and CD81. Moreover, cytofluorimetric analysis highlighted the expression of mesenchymal, stem, epithelial and endothelial markers. In the in vitro wound healing assay on HaCaT cells, AH-EVs induced a significantly faster wound repair, comparable to the effects of MSC-EVs, and promoted HaCaT cell viability and proliferation. We provide evidence, herein, of the possible AH-EV origin from stromal cells, limbal epithelial/stem cells, ciliary epithelium and corneal endothelium. In addition, we showed their in vitro proliferative and regenerative capacities.

Exosomal MicroRNA Profiling in Vitreous Humor Derived From Pathological Myopia Patients

Purpose

Pathologic myopia (PM) is one of the primary causes of blindness. This study aims to explore the possible relations between the composition of microRNA in vitreous exosomes of patients with PM and the progression of myopic maculopathy.

Methods

Vitreous humor (VH) samples were collected from patients undergoing retinal surgery. A total of 15 and 12 VH samples were obtained from patients with PM and control, respectively. The PM group was divided into PM-L (G2) and PM-H groups (G3 and G4) in order to explore differentially expressed microRNAs (DEMs) that account for the relatively poor prognosis in G3 and G4 myopic maculopathy. A Weighted Gene Co-Expression Network Analysis (WGCNA) was conducted to find the persistently altered key microRNAs in myopic maculopathy progression. The Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genome (KEGG) pathway enrichment analysis were used.

Results

High purity exosomes were extracted from the vitreous fluid of patients with PM and control. The top five downregulated DEMs of PM-H versus PM-L can reflect the tendency of deterioration of PM-H myopic maculopathy. MiR-143-3p and miR-145-5p, which were found in WGCNA, may participate in the development of myopic maculopathy. These microRNAs all relate to the insulin resistance pathway.

Conclusions

This is the first study to explore the relations between the progression of myopic maculopathy and vitreous exosomal microRNAs. Vitreous exosomal miR-143-3p and miR-145-5p can be considered biomarkers for patients with PM, and the vitreous exosomal DEM associated with PM-H may represent alarming signals of myopic maculopathy deterioration.

Mass spectrometry-based identification of new serum biomarkers in patients with latent infection pulmonary tuberculosis

Noninvasive and simple indicators for diagnosing latent tuberculosis (TB) infection (LTBI) and tracking progression from latent infection to active TB infection are still desperately needed. The aim of this study was to screen and identify possible biomarkers for diagnosing LTBI and monitoring the progression from latent infection to active TB infection, as well as to investigate the underlying processes and functions. To assess changes in metabolite composition associated with active tuberculosis infection in humans, whole blood supernatants were collected from patients with LTBI, drug-susceptible TB patients, drug-resistant TB patients, and healthy controls. The metabolites in all serum samples were extracted by oscillatory, deproteinization, and then detected by liquid chromatography-tandem mass spectrometry/MS analysis. Normalization by Pareto-scaling method, the difference analysis was carried out by Metaboanalyst 4.0 software, and 1-way analysis of variance analysis among groups showed that P-value < 0.05 was regarded as a different metabolite. To clarify the dynamic changes and functions of differential metabolites with disease progression, and explore its significance and mechanism as a marker by further cluster analysis, functional enrichment analysis, and relative content change analysis of differential metabolites. 65 metabolites were substantially different in four groups. Differential metabolites such as Inosine and Prostaglandin E1 may be important blood indicators for diagnosing mycobacterium tuberculosis latent infection, which were all tightly connected to amino acid metabolism, Biosynthesis of various secondary metabolites, Nucleotide metabolism, Endocrine system, Immune system, Lipid metabolism, and Nervous system. This study screened and identified Inosine, 16, 16-dimethyl-6-keto Prostaglandin E1, Theophylline, and Cotinine as potential serum biomarkers for diagnosing latent TB infection, and Cotinine as potential biomarkers for monitoring disease progression from healthy population to LTBI and then to active TB including drug-resistant TB infection and sensitive TB infection. Furthermore, this research provides a preliminary experimental basis to further investigate the development of metabolomics-based diagnosis of LTBI and monitoring the progress from latent infection to active TB infection.

Exosomes in the visual system: New avenues in ocular diseases

Exosomes are a subgroup of membrane-bound extracellular vesicles secreted by all cell types and present virtually in all biological fluids. The composition of exosomes in the same cell type varies in healthy and disease conditions. Hence, exosomes research is a prime focus area for clinical research in cancer and numerous age-related metabolic syndromes. Functions of exosomes include crucial cell-to-cell communication that mediates complex cellular processes, such as antigen presentation, stem cell differentiation, and angiogenesis. However, very few studies reported the presence and role of exosomes in normal physiological and pathological conditions of specialized ocular tissues of the eye and ocular cancers. The eye being a protected sense organ with unique connectivity with the rest of the body through the blood and natural passages, we believe that the role of exosomes in ocular tissues will significantly improve our understanding of ocular diseases and their interactions with the rest of the body. We present a review that highlights the existence and function of exosomes in various ocular tissues, their role in the progression of some of the neoplastic and non-neoplastic conditions of the eyes.

Proteomic Profiling of Aqueous Humor Exosomes from Age-related Macular Degeneration Patients

Purpose: The alteration of the exosomal proteins in the aqueous humor (AH) is linked to the development of eye diseases. The goal of this study was to examine the exosomal protein profile of patients with age-related macular degeneration (AMD) to better understand their role in the pathogenesis of AMD. Methods: Exosomes were isolated from the AH of 28 AMD and 25 control eyes. The quality, concentration, and size distribution of exosomes were measured using a nanoparticle tracking analysis system (NTA). Total exosomal proteins from each sample were purified and digested with trypsin for liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. Results: Based on LC-MS/MS analysis, we got 105 exosomal peptides from AMD and control patients. Gene ontology (GO) analysis in the biology process revealed that exosomal proteins of AMD were enriched in the lipoprotein metabolic process. T-test analysis revealed six exosomal proteins in patients with AMD were significantly different from controls. Comparing the exosomal protein profile of AMD patients who were receiving anti-VEGF therapy, we observed the amount of two proteins decreased with the duration of the anti-VEGF treatment time. Conclusions: In this study, we successfully isolated and purified AH exosomes. Our results provide pioneering findings for the exosomal protein profile in AMD development and under therapy. These unique proteins could be the new targets for drug discovery or biological markers for evaluating therapeutic efficacy.