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Greiner JV, Glonek T. Phospholipid analyses of rabbit ocular surface tissues. Exp Eye Res 2024; 243:109911. [PMID: 38663719 DOI: 10.1016/j.exer.2024.109911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Revised: 04/20/2024] [Accepted: 04/22/2024] [Indexed: 05/01/2024]
Abstract
The tissues of the integument covering the ocular surface comprise a mucus membrane functioning as a protective physical barrier and has the ability to mount a defensive inflammatory response. Since lipid metabolism has a role in both of these functions, we studied normal membrane phospholipids (PL) of the cornea and bulbar conjunctiva to (1) determine baseline PL profiles of these tissues, (2) compare and contrast these individual PL metabolite profiles as well as groups of metabolites, and (3) describe pathway-specific metabolic interrelations among these tissues. Corneal and conjunctival tissue samples were isolated from rabbit eyes (n = 30) and extracted with chloroform-methanol using a modified Folch procedure. 31P nuclear magnetic resonance spectroscopy was used to qualitatively and quantitatively measure tissue PL profiles. The cornea and conjunctiva, respectively, have the following PL composition (mole % of total detected phospholipid): phosphatidylglycerol (PG) -, 0.4; lysophosphatidylethanolamine 1.2, -; phosphatidic acid -, 0.4; diPG (cardiolipin) 2.1, 3.5; unknown PL at the chemical shift of 0.13 δ 1.5, 0.9; ethanolamine plasmalogen 11.2, 13.0; phosphatidylethanolamine 11.5, 12.8; phosphatidylserine 8.9, 10.1; sphingomyelin 10.2, 10.7; lysophosphatidylcholine 0.9, 1.4; phosphatidylinositol 5.3, 5.3; phosphatidylcholine (PC) plasmalogen or alkylacylPC 2.2, 1.9; PC 45.1, 40.0. In addition, 28 PL metabolic indices were calculated from these data, which permitted pathway-specific lipid analyses. This study (1) establishes PL profiles of the two ocular tissues of the integument that cover the surface of the eye, (2) compares and contrasts indices comprised of ratios and combinations of PL, and (3) describes pathway-specific metabolic interrelations among these tissues to serve as baselines for studies involving the distribution of tissue phospholipids.
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Affiliation(s)
- Jack V Greiner
- Department of Ophthalmology, Harvard Medical School, 243 Charles St., Boston, MA, USA; Schepens Eye Research Institute of Massachusetts Eye and Ear Infirmary, 20 Staniford St., Boston, MA, USA; Clinical Eye Research of Boston, 5 Whittier Pl, Ste. 102, Boston, MA, USA; Magnetic Resonance Laboratory, Chicago College of Osteopathic Medicine, Chicago, 5200 S. Ellis Ave., IL, USA.
| | - Thomas Glonek
- Clinical Eye Research of Boston, 5 Whittier Pl, Ste. 102, Boston, MA, USA; Magnetic Resonance Laboratory, Chicago College of Osteopathic Medicine, Chicago, 5200 S. Ellis Ave., IL, USA.
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Chaves-Filho AM, Braniff O, Angelova A, Deng Y, Tremblay MÈ. Chronic inflammation, neuroglial dysfunction, and plasmalogen deficiency as a new pathobiological hypothesis addressing the overlap between post-COVID-19 symptoms and myalgic encephalomyelitis/chronic fatigue syndrome. Brain Res Bull 2023; 201:110702. [PMID: 37423295 DOI: 10.1016/j.brainresbull.2023.110702] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Revised: 05/13/2023] [Accepted: 07/06/2023] [Indexed: 07/11/2023]
Abstract
After five waves of coronavirus disease 2019 (COVID-19) outbreaks, it has been recognized that a significant portion of the affected individuals developed long-term debilitating symptoms marked by chronic fatigue, cognitive difficulties ("brain fog"), post-exertional malaise, and autonomic dysfunction. The onset, progression, and clinical presentation of this condition, generically named post-COVID-19 syndrome, overlap significantly with another enigmatic condition, referred to as myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Several pathobiological mechanisms have been proposed for ME/CFS, including redox imbalance, systemic and central nervous system inflammation, and mitochondrial dysfunction. Chronic inflammation and glial pathological reactivity are common hallmarks of several neurodegenerative and neuropsychiatric disorders and have been consistently associated with reduced central and peripheral levels of plasmalogens, one of the major phospholipid components of cell membranes with several homeostatic functions. Of great interest, recent evidence revealed a significant reduction of plasmalogen contents, biosynthesis, and metabolism in ME/CFS and acute COVID-19, with a strong association to symptom severity and other relevant clinical outcomes. These bioactive lipids have increasingly attracted attention due to their reduced levels representing a common pathophysiological manifestation between several disorders associated with aging and chronic inflammation. However, alterations in plasmalogen levels or their lipidic metabolism have not yet been examined in individuals suffering from post-COVID-19 symptoms. Here, we proposed a pathobiological model for post-COVID-19 and ME/CFS based on their common inflammation and dysfunctional glial reactivity, and highlighted the emerging implications of plasmalogen deficiency in the underlying mechanisms. Along with the promising outcomes of plasmalogen replacement therapy (PRT) for various neurodegenerative/neuropsychiatric disorders, we sought to propose PRT as a simple, effective, and safe strategy for the potential relief of the debilitating symptoms associated with ME/CFS and post-COVID-19 syndrome.
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Affiliation(s)
| | - Olivia Braniff
- Division of Medical Sciences, University of Victoria, Victoria, British Columbia, Canada
| | - Angelina Angelova
- Université Paris-Saclay, CNRS, Institut Galien Paris-Saclay, F-91400 Orsay, France
| | - Yuru Deng
- Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, China.
| | - Marie-Ève Tremblay
- Division of Medical Sciences, University of Victoria, Victoria, British Columbia, Canada; Department of Molecular Medicine, Université Laval, Québec City, Québec, Canada; Neurology and Neurosurgery Department, McGill University, Montréal, Québec, Canada; Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada; Centre for Advanced Materials and Related Technology (CAMTEC) and Institute on Aging and Lifelong Health (IALH), University of Victoria, Victoria, British Columbia, Canada.
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Altera A, Barone V, Kondova I, Langermans JAM, Gentile M, Pin C, Nicoletti C, Bertelli E. Light-Induced Smooth Endoplasmic Reticulum Rearrangement in a Unique Interlaced Compartmental Pattern in Macaca mulatta RPE. Invest Ophthalmol Vis Sci 2021; 62:32. [PMID: 34967853 PMCID: PMC8727310 DOI: 10.1167/iovs.62.15.32] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Purpose To investigate light-induced modifications of the smooth endoplasmic reticulum of the RPE in primates. Methods Eyes of three terminally anesthetized Rhesus monkeys were exposed to 5000 lux for 10 minutes or kept in the dark. Transmission electron microscopy and electron tomography were conducted on small fragments of retina sampled from different regions of the retina. Results RPE cells smooth endoplasmic reticulum shows a previously unknown arrangement characterized by an interlaced compartmental pattern (ICP). Electron tomograms and 3D-modelling demonstrated that the smooth endoplasmic reticulum with an ICP (ICPSER) consisted of four parallel, independent and interwoven networks of tubules arranged as interconnected coiled coils. Its architecture realized a compact labyrinthine structure of tightly packed tubules stabilized by intertubular filamentous tethers. On average, the ICPSER is present in about 14.6% of RPE cells. Although ICPSER was preferentially found in cells located in the peripheral and in the para/perifoveal retina, ICPSER cells significantly increased in number upon light exposure in the para/perifovea and in the fovea. Conclusions An ICPSER is apparently a unique feature to primate RPE. Its rapid appearance in the area centralis of the retina upon light exposure suggests a function related to the foveate structure of primate retina or to the diurnal habits of animals that may require additional protection from photo-oxidation or enhanced requests of visual pigments regeneration.
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Affiliation(s)
- Annalisa Altera
- Department of Life Sciences, University of Siena, Siena, Italy.,Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy
| | - Virginia Barone
- Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy
| | - Ivanela Kondova
- Division of Pathology and Microbiology, Animal Science Department, Biomedical Primate Research Centre, Rijswijk, the Netherlands
| | - Jan A M Langermans
- Animal Science Department, Biomedical Primate Research Centre, Rijswijk, the Netherlands.,Department Population Health Sciences, Division Animals in Science and Society, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands
| | | | - Carmen Pin
- Clinical Pharmacology and Safety Sciences, BioPharmaceuticals R&D, AstraZeneca, Cambridge, United Kingdom
| | - Claudio Nicoletti
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - Eugenio Bertelli
- Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy
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