Association of Primary Open-Angle Glaucoma with Diabetic Retinopathy among Patients with Type 1 and Type 2 Diabetes: A Large Global Database Study.

PURPOSE: To assess the correlation between primary open-angle glaucoma (POAG) and the risk of developing diabetic retinopathy (DR) in patients with type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM). DESIGN: A retrospective cohort study leveraging the global patient database of TriNetX Research Network. PARTICIPANTS: The study included 44 359 patients with diabetes mellitus (DM) with POAG and 4 393 300 patients with DM without any glaucoma ≥ 18 years of age. Propensity score matching harmonized the cohorts to 39 680 patients each, covering diagnoses from January 1, 2005, to January 1, 2023. METHODS: We analyzed data using specific International Classification of Diseases, 10th Revision (ICD-10) codes for DM and glaucoma. We matched the cohorts using propensity score matching, adjusting for age, sex, race/ethnicity, blood markers, relevant medical history, and ophthalmic service use. MAIN OUTCOME MEASURES: The primary outcome was the first-time occurrence of DR, including nonproliferative DR (NPDR) and proliferative DR (PDR), in patients with DM with and without glaucoma at 1-, 5-, and 10-year intervals from their individual index dates. RESULTS: At 10 years, patients with T1DM with POAG exhibited a heightened risk for any DR (adjusted risk ratios [RRs], 4.12; 95% confidence interval [CI], 3.05-5.57, P < 0.0001) and PDR (RR, 7.02; 95% CI, 3.62-13.61, P < 0.0001). Patients with T2DM and POAG also faced an increased 10-year risk for any DR (RR, 2.47; 95% CI, 2.28-2.68, P < 0.0001) and PDR (RR, 3.82; 95% CI, 3.09-4.70, P < 0.0001). The combined association of POAG on DR risk in those with T1DM and T2DM at 10 years was found to be significantly higher among patients with POAG (5.45%) compared with those without glaucoma (2.12%) (adjusted hazard ratio [aHR], 2.33; 95% CI, 2.14-2.53). The cumulative incidence of DR was significantly higher in the POAG group compared with nonglaucoma counterparts after a decade (log-rank P < 0.001). CONCLUSIONS: Our findings underscore a substantial association between POAG and DR development in both T1DM and T2DM patients, emphasizing the need for vigilant screening and comprehensive management in glaucomatous patients with DM to mitigate the risk of DR. Future research should delve into elucidating the causal mechanisms driving these observed associations. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Appropriate patient population for future visual system axon regeneration therapies.

A number of blinding diseases caused by damage to the optic nerve result in progressive vision loss or loss of visual acuity. Secondary glaucoma results from traumatic injuries, pseudoexfoliation or pigmentary dispersion syndrome. Progressive peripheral vision loss is common to all secondary glaucoma irrespective of the initial event. Axon regeneration is a potential therapeutic avenue to restore lost vision in these patients. In contrast to the usual approach of having the worst possible patient population for initial therapies, axon regeneration may require consideration of appropriate patient population even for initial treatment trials. The current state of axon regeneration therapies, their potential future and suitable patient population when ready is discussed in this perspective. The selection of patients are important for adoption of axon regeneration specifically in the areas of central nervous system regenerative medicine. This article is categorized under: Neurological Diseases > Molecular and Cellular Physiology Neurological Diseases > Biomedical Engineering Metabolic Diseases > Molecular and Cellular Physiology.

Currently available prostanoids for the treatment of glaucoma and ocular hypertension: A review.

Recent advancements in prostaglandin analogs (PGAs) have reinforced their role in managing intraocular pressure (IOP). Latanoprost excels in 24-h IOP control, while various PGAs offer similar effectiveness and side effects, generic PGAs perform as well as branded ones, and a notable IOP rise observed upon PGA discontinuation. Formulations with or without preservatives show comparable IOP reduction and adherence, often surpassing benzalkonium chloride (BAK)-preserved options. Emergent PGAs, such as latanoprostene bunod, fixed-dose netarsudil combined with latanoprost, and omidenepag Isopropyl, offer enhanced or non-inferior IOP reduction. The bimatoprost implant introduces a novel administration method with effective IOP reduction. These developments underscore ongoing progress in PGA-focused ophthalmological research. This article offers a comprehensive review of available prostanoid analogs and explores new developments.

Mass spectrometry dataset of LC-MS lipidomics analysis of Xenopus laevis optic nerve.

CNS injuries of the anuran amphibian, Xenopus laevis, are uniquely suited for studying the molecular compositions of neuronal regeneration of retinal ganglion cells (RGC) due to a functional recovery of optic axons disparate to adult mammalian analogues. RGCs and their optic nerve axons undergo irreversible neurodegeneration in glaucoma and associated optic neuropathies, resulting in blindness in mammals. Conversely, Xenopus demonstrates RGC lifetime-spanning regenerative capabilities after optic nerve crush [1], inciting opportunities to compare de novo regeneration and develop efficient pharmaceutical approaches for vision restoration. Studies revealing lipidome alterations during optic nerve regeneration are sparse and could serve as a solid foundation for these underlying molecular changes. We profile the lipid changes in a transgenic line of 1 year old Xenopus laevis Tg(islet2b:gfp) frogs that were either left untreated (naïve) or had a monocular surgery of either a left optic crush injury (crush) or sham surgery (sham). Matching controls of uninjured right optic nerves were also collected (control). Tg(islet2b:gfp) frogs were allowed to recover for 7,12,18, and 27 days post optic nerve crush. Following euthanasia, the optic nerves were collected for lipidomic analysis. A modified Bligh and Dyer method [2] was used for lipid extraction, followed by untargeted mass spectrometry lipid profiling with a Q Exactive Orbitrap Mass Spectrometer coupled with a Vanquish Horizon Binary UHPLC LC-MS system (LC MS-MS). The raw scans were analyzed and quantified with LipidSearch 5.0 and the statistical analysis was conducted through Metaboanalyst 5.0. This data is available at Metabolomics Workbench, study ID [ST002414].

Metabolomics dataset of zebrafish optic nerve regeneration after injury.

Zebrafish (Danio rerio) have the capacity for successful adult optic nerve regeneration. In contrast, mammals lack this intrinsic ability and undergo irreversible neurodegeneration seen in glaucoma and other optic neuropathies. Optic nerve regeneration is often studied using optic nerve crush, a mechanical neurodegenerative model. Untargeted metabolomic studies within successful regenerative models are deficient. Evaluation of tissue metabolomic changes in active zebrafish optic nerve regeneration can elucidate prioritized metabolite pathways that can be targeted in mammalian systems for therapeutic development. Female and male (6 month to 1 year old wild type) right zebrafish optic nerves were crushed and collected three days after. Contralateral, uninjured optic nerves were collected as controls. The tissue was dissected from euthanized fish and frozen on dry ice. Samples were pooled for each category (female crush, female control, male crush, male control) and pooled at n = 31 to obtain sufficient metabolite concentrations for analysis. Optic nerve regeneration at 3 days post crush was demonstrated by microscope visualization of GFP fluorescence in Tg(gap43:GFP) transgenic fish. Metabolites were extracted using a Precellys Homogenizer and a serial extraction method: (1) 1:1 Methanol/Water and (2) 8:1:1 Acetonitrile/Methanol/Acetone. Metabolites were analyzed by untargeted liquid chromatography-mass spectrometry (LC MS-MS) profiling using a Q-Exactive Orbitrap instrument coupled with Vanquish Horizon Binary UHPLC LC-MS system. Metabolites were identified and quantified using Compound Discoverer 3.3 and isotopic internal metabolites standards.

Glaucomatous aqueous humor vesicles are smaller and differ in composition compared to controls.

Cells communicate with each other using vesicles of varying sizes, including a specific repertoire known as exosomes. We isolated aqueous humor (AH)-derived vesicles using two different methods: ultracentrifugation and an exosome isolation kit. We confirmed a unique vesicle size distribution in the AH derived from control and primary open-angle glaucoma (POAG) patients using various techniques, including Nanotracker, dynamic light scattering, atomic force imaging, and electron microscopy. Bonafide vesicle and/or exosome markers were present by dot blot in both control and POAG AH-derived vesicles. Marker levels differed between POAG and control samples, while non-vesicle negative markers were absent in both. Quantitative labeled (iTRAQ) proteomics showed a reduced presence of a specific protein, STT3B, in POAG compared to controls, which was further confirmed using dot blot, Western blot, and ELISA assays. Along the lines of previous findings with AH profiles, we found vast differences in the total phospholipid composition of AH vesicles in POAG compared to controls. Electron microscopy further showed that the addition of mixed phospholipids alters the average size of vesicles in POAG. We found that the cumulative particle size of type I collagen decreased in the presence of Cathepsin D, which normal AH vesicles were able to protect against, but POAG AH vesicles did not. AH alone had no effect on collagen particles. We observed a protective effect on collagen particles with an increase in artificial vesicle sizes, consistent with the protective effects observed with larger control AH vesicles but not with the smaller-sized POAG AH vesicles. Our experiments suggest that AH vesicles in the control group provide greater protection for collagen beams compared to POAG, and their increased vesicle sizes are likely contributing factors to this protection.

Ocular Treatments Targeting Separate Prostaglandin Receptors in Mice Exhibit Alterations in Intraocular Pressure and Optic Nerve Lipidome.

Background: Prostaglandin (PG) receptor agonists are the first-line eyedrop medication treatment for glaucoma. The pathophysiology of this disease is not completely known, and elevated intraocular pressure (IOP) is the key risk factor. The membranes of the axons (of the retinal ganglion cells) passing through the optic nerve (ON) head experience significant damage. Lipids are an essential component of the cell's membranes, and their profile changes owing to neurodegeneration. In this investigation, three agonists for distinct PG receptors were used to lower IOP and to determine their effect on the ON lipids. We utilized DBA/2J mice as a model of progressive IOP increase and C57BL/6J mice as a model of ON crush. Methods: DBA/2J and C57BL/6J mice were treated daily for 2 weeks with Latanoprost, PF-04217329, or Rivenprost. The IOP was measured every 2 days and pattern electroretinogram was conducted for DBA/2J throughout the study. Lipidomics of ONs were performed for each model and treatment group. Results: Of the tested compounds, Latanoprost and Rivenprost were the most effective agents decreasing IOP in DBA/2J mice. Triglyceride levels increased in the ONs of DBA/2J mouse model, but phosphatidylethanolamine levels underwent highest level changes in the C57BL/6J mouse model when treated with Latanoprost. Conclusions: Topical ocular FP- and EP4-receptor agonists appreciably lowered IOP in the DBA/2J mice representing pigmentary glaucoma. The observed changes in ON lipidomics in the different models of neurodegeneration suggest possible use of such measures in the development of more effective medicines for both IOP reduction and ON protection.

Glycerophospholipid Analysis of Optic Nerve Regeneration Models Indicate Potential Membrane Order Changes Associated with the Lipidomic Shifts.

Purpose: Optic nerve (ON) injury causes irreversible degeneration, leading to vision loss that cannot be restored with available therapeutics. Current therapies slow further degeneration but do not promote regeneration. New regenerative factors have been discovered that are successful in vivo. However, the mechanisms of efficient long-distance regeneration are still unknown. Membrane expansion by lipid insertion is an essential regenerative process, so lipid profiles for regenerating axons can provide insight into growth mechanisms. This article's analysis aims to add to the increasingly available ON regeneration lipid profiles and relate it to membrane order/properties. Methods: In this study, we present an analysis of glycerophospholipids, one of the largest axonal lipid groups, from three mammalian ON regeneration lipid profiles: Wnt3a, Zymosan + CPT-cAMP, and Phosphatase/Tensin homolog knockout (PTENKO) at 7 and 14 days post crush (dpc). Significant lipid classes, species, and ontological properties were crossreferenced between treatments and analyzed using Metaboanalyst 5.0 and Lipid Ontology (LION). Membrane order changes associated with significant lipid classes were evaluated by C-Laurdan dye and exogenous lipids provided to a neuroblastoma cell line. Results and Conclusions: At 7 dpc, ONs show increased lysoglycerophospholipids and decreased phosphatidylethanolamines (PEs)/negative intrinsic curvature lipids. At 14 dpc, regenerative treatments show divergence: Wnt3a displays higher lysoglycerophospholipid content, while Zymosan and PTENKO decrease lysoglycerophospholipids and increase phosphatidylcholine (PC)-related species. Membrane order imaging indicates lysoglycerophospholipids decreases membrane order while PE and PC had no significant membrane order effects. Understanding these changes will allow therapeutic development targeting lipid metabolic pathways that can be used for vision loss treatments.

Isolation of Mitochondrial Lipids and Mass Spectrometric Analysis.

Mitochondria participate in many important metabolic processes in the body. The lipid profile of mitochondria is especially important in membrane regulation and pathway signaling. The isolation and study of these lipids can provide unparalleled information about the mechanisms behind these cellular processes. In this chapter, we describe a protocol to isolate mitochondrial lipids from homogenized murine optic nerves. The lipid extraction was performed using butanol-methanol (BUME) and subsequently analyzed using liquid chromatography-mass spectrometry. Further analysis of the raw data was conducted using LipidSearch™ and MetaboAnalyst 4.0.

Characterization of Gangliosides from Mouse Optic Nerve Samples Using Mass Spectrometry.

This chapter focuses on identifying gangliosides in the optic nerve of the mouse using mass spectrometry techniques. The described protocol will also permit the characterization of the sample's lipidome. Two deuterium-labeled ganglioside standards and a general lipid class standard will be utilized for extraction efficiency and quantification. Using reversed-phase high-performance liquid chromatography (HPLC) coupled to a Q Exactive mass spectrometer, the samples will be analyzed. The method will consist of both an untargeted approach and a targeted approach with a ganglioside-specific inclusion list.

High-Resolution Liquid Chromatography-Mass Spectrometry for Lipidomics.

Liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) is a powerful tool for identification and classification of lipids. Ultra-high performance liquid chromatography (UHPLC) allows for robust separations of complex mixtures, while high-resolution mass spectrometry (HRMS) identifies compounds with efficiency and accuracy (Zullig T and Kofeler HC, Mass Spectrom Rev 40:162-176, 2021). The high specificity and sensitivity of mass spectrometry makes it the method of choice when analyzing lipids (Kofeler HC, J Lipid Res 62:100138, 2021). Untargeted mass spectrometry identifies all lipids within a sample and is useful for identification and further discovery. This chapter describes the use of a Q Exactive mass spectrometer to perform an untargeted LC-MS/MS lipidomics analysis.

Lipidomics Analysis with Triple Quadrupole Mass Spectrometry.

Lipids serve an essential role in multiple cellular functions including signaling, metabolism, energy storage, and membrane constitution. Lipidomics, the study of lipids using analytical chemistry, allows for the study of disease states and cellular metabolism. Shotgun lipidomics is a technique that involves direct-infusion electrospray ionization (ESI) and analysis with a triple quadrupole mass spectrometer. Triple quadrupole mass spectrometry is ideally suited for lipidomics analysis because it allows for class-specific identification of lipids. Individual lipid class can be identified by the adjustment of three parameters-collision energy, ion mode, and scan type. This chapter describes the use of a triple quadrupole mass spectrometer, the TSQ Quantum Access MAX, to perform lipidomics analysis with high sensitivity, accuracy, and precision.

Analysis of Cholesterol Lipids Using Gas Chromatography Mass Spectrometry.

An optimized Bligh and Dyer protocol and subsequent derivatization is described in this chapter for the extraction of free cholesterol and cholesterol esters from tissue samples. Quantification analysis of lipid species is then described utilizing gas chromatography-mass spectrometry, the ideal method for analysis of volatile organic compounds and extraction of sterols.

Analyses and Localization of Phosphatidylcholine and Phosphatidylserine in Murine Ocular Tissue Using Imaging Mass Spectrometry.

Imaging mass spectrometry (IMS) allows for spatial visualization of proteins, lipids, and metabolite distributions in a tissue. Identifying these compounds through mass spectrometry, combined with mapping the compound distribution in the sample in a targeted or untargeted approach, renders IMS a powerful tool for lipidomics. IMS analysis for lipid species such as phosphatidylcholine and phosphatidylserine allows researchers to pinpoint areas of lipid deficiencies or accumulations associated with ocular disorders such as age-related macular degeneration and diabetic retinopathy. Here, we describe an end-to-end IMS approach from sample preparation to data analysis for phosphatidylcholine and phosphatidylserine analysis.

Capillary Electrophoresis Plasma Fractionation for Lipids Analysis.

Extraction of lipids has mainly used density liquid phase separation techniques; however, these methods are limited by their broad extraction and lack specificity. Complex mixtures like blood plasma contain multiple lipid classes, whose distribution in the body are mediated by protein-lipid interactions and integration of lipids in larger lipoprotein complexes. The capillary electrophoresis system separates complex mixtures by electrokinetic forces that preserve protein-lipid complexation and allow for the fractionation of samples. Here we present a methodology for fractionating plasma using the capillary electrophoresis system.

Characterization of Trabecular Meshwork Mechanical Property Modulation After Application of Lipids.

Treatment of lipids endogenous to the aqueous humor of the eye could serve as a potential therapy to slow the progression of glaucoma. Herein, we describe the method to treat trabecular meshwork samples in vitro with lipids and characterize changes in the samples' stiffness.

C-Laurdan: Membrane Order Visualization of HEK293t Cells by Confocal Microscopy.

Membrane order is a biophysical characteristic dependent on cellular lipid makeup. Cells regulate the membrane structure as it affects membrane-bound protein activity levels and membrane stability. Spatial organization of membrane lipids, such as lipid rafts, is a proposed theory that has been indirectly measured through polarity-sensitive fluorescent dyes. C-Laurdan is one such dye that penetrates plasma and internal membranes. C-Laurdan is excited by a single 405 nm photon and emits in two distinct ranges depending on membrane order. Herein, we present a protocol for staining HEK293t cells with C-Laurdan and acquiring ratiometric images using a revised ImageJ macro and confocal microscopy. An example figure is provided depicting the effects of methyl-ß-cyclodextrin, known to remove lipid rafts through cholesterol sequestration, on HEK293t cells. Further image analysis can be performed through region of interest (ROI) selection tools.

Analysis of Brain Metabolites Using Two Complementary Ultrahigh-Performance Liquid Chromatography-Mass Spectrometry Methods.

Metabolomics continues to progress, but obstacles remain. The preservation of metabolites in the target tissue and gathering information on the current metabolic state of the organism of interest proves challenging. Robustness, reproducibility, and reliable quantification are necessary for confident metabolite identification and should always be considered for effective biomarker discovery. Recent advancements in analytical platforms, techniques, and data analysis make metabolomics a promising omics for significant research. However, there is no single approach to effectively capturing the metabolome. Coupling separation techniques may improve the power of the analysis and facilitate confident metabolite identification, especially when performing untargeted metabolomics. In this chapter, we will present an untargeted metabolomic analysis of brain tissue from C57BL/6 mice using two UHPLC-MS methods based on reversed-phase and HILIC chromatography.