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Aschner M, Skalny AV, Paoliello MMB, Tinkova MN, Martins AC, Santamaria A, Lee E, Rocha JBT, Farsky SHP, Tinkov AA. Retinal toxicity of heavy metals and its involvement in retinal pathology. Food Chem Toxicol 2024; 188:114685. [PMID: 38663763 DOI: 10.1016/j.fct.2024.114685] [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: 02/21/2024] [Revised: 04/16/2024] [Accepted: 04/22/2024] [Indexed: 05/04/2024]
Abstract
The objective of the present review is to discuss epidemiological evidence demonstrating the association between toxic metal (Cd, Pb, Hg, As, Sn, Ti, Tl) exposure and retinal pathology, along with the potential underlying molecular mechanisms. Epidemiological studies demonstrate that Cd, and to a lesser extent Pb exposure, are associated with age-related macular degeneration (AMD), while the existing evidence on the levels of these metals in patients with diabetic retinopathy is scarce. Epidemiological data on the association between other toxic metals and metalloids including mercury (Hg) and arsenic (As), are limited. Clinical reports and laboratory in vivo studies have shown structural alterations in different layers of retina following metal exposure. Examination of retina samples demonstrate that toxic metals can accumulate in the retina, and the rate of accumulation appears to increase with age. Experimental studies in vivo and in vitro studies in APRE-19 and D407 cells demonstrate that toxic metal exposure may cause retinal damage through oxidative stress, apoptosis, DNA damage, mitochondrial dysfunction, endoplasmic reticulum stress, impaired retinogenesis, and retinal inflammation. However, further epidemiological as well as laboratory studies are required for understanding the underlying molecular mechanisms and identifying of the potential therapeutic targets and estimation of the dose-response effects.
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Affiliation(s)
- Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, New York, NY 10461, USA
| | - Anatoly V Skalny
- Laboratory of Ecobiomonitoring and Quality Control, Yaroslavl State University, Yaroslavl, 150003, Russia; Center of Bioelementology and Human Ecology, IM Sechenov First Moscow State Medical University (Sechenov University), Moscow, 119435, Russia
| | - Monica M B Paoliello
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, New York, NY 10461, USA
| | | | - Airton C Martins
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, New York, NY 10461, USA
| | - Abel Santamaria
- Facultad de Ciencias, Universidad Nacional Autónoma de México, Mexico City, 04510, Mexico; Laboratorio de Nanotecnología y Nanomedicina, Departamento de Cuidado de La Salud, Universidad Autónoma Metropolitana-Xochimilco, Mexico City 04960, Mexico
| | - Eunsook Lee
- Department of Pharmaceutical Sciences, Florida A&M University, Tallahassee, FL 32307, USA
| | - Joao B T Rocha
- Departamento de Bioquímica e Biologia Molecular, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria 97105-900, RS, Brazil
| | - Sandra H P Farsky
- Department of Clinical and Toxicological Analyses, School of Pharmaceutical Sciences, University of Sao Paulo, São Paulo 05508-000, SP, Brazil
| | - Alexey A Tinkov
- Laboratory of Ecobiomonitoring and Quality Control, Yaroslavl State University, Yaroslavl, 150003, Russia; Center of Bioelementology and Human Ecology, IM Sechenov First Moscow State Medical University (Sechenov University), Moscow, 119435, Russia.
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de los Santos C, Pastor JC, Calonge M. Mercury intoxication and ophthalmic involvement: An update review. FRONTIERS IN TOXICOLOGY 2023; 5:1148357. [PMID: 37063600 PMCID: PMC10102333 DOI: 10.3389/ftox.2023.1148357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 03/22/2023] [Indexed: 04/03/2023] Open
Abstract
Human intoxication after mercury exposure is a rare condition that can cause severe damage to the central nervous, respiratory, cardiovascular, renal, gastrointestinal, skin, and visual systems and represents a major public health concern. Ophthalmic involvement includes impaired function of the extraocular muscles and the eyelids, as well as structural changes in the ocular surface, lens, retina, and optic nerve causing a potential irreversible damage to the visual system. Although, there are many pathways for poisoning depending on the mercury form, it has been suggested that tissue distribution does not differ in experimental animals when administered as mercury vapor, organic mercury, or inorganic mercury. Additionally, visual function alterations regarding central visual acuity, color discrimination, contrast sensitivity, visual field and electroretinogram responses have also been described widely. Nevertheless, there is still controversy about whether visual manifestations occur secondary to brain damage or as a direct affectation, and which ocular structure is primarily affected. Despite the use of some imaging techniques such as in vivo confocal microscopy of the cornea, optical coherence tomography (OCT) of the retina and optic nerve, and functional tests such as electroretinography has helped to solve in part this debate, further studies incorporating other imaging modalities such as autofluorescence, OCT angiography or adaptive optics retinal imaging are needed. This review aims to summarize the published structural and functional alterations found in the visual system of patients suffering from mercury intoxication.
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Affiliation(s)
- Cristian de los Santos
- Institute of Applied Ophthalmobiology (IOBA), Universidad de Valladolid, Valladolid, Spain
- *Correspondence: Cristian de los Santos,
| | - J. Carlos Pastor
- Institute of Applied Ophthalmobiology (IOBA), Universidad de Valladolid, Valladolid, Spain
- Centro en Red de Medicina Regenerativa y Terapia Celular. Junta de Castilla y León, Valladolid, Spain
| | - Margarita Calonge
- Institute of Applied Ophthalmobiology (IOBA), Universidad de Valladolid, Valladolid, Spain
- Centro en Red de Medicina Regenerativa y Terapia Celular. Junta de Castilla y León, Valladolid, Spain
- CIBER-BBN, Carlos III National Institute of Health, Madrid, Spain
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Tousignant B, Chatillon A, Philibert A, Da Silva J, Fillion M, Mergler D. Visual Characteristics of Adults with Long-Standing History of Dietary Exposure to Mercury in Grassy Narrows First Nation, Canada. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2023; 20:4827. [PMID: 36981736 PMCID: PMC10049103 DOI: 10.3390/ijerph20064827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 02/23/2023] [Accepted: 03/07/2023] [Indexed: 06/18/2023]
Abstract
Since the 1960s, Grassy Narrows First Nation (Ontario, Canada) has been exposed to methyl mercury (Hg) through fish consumption, resulting from industrial pollution of their territorial waters. This cross-sectional study describes the visual characteristics of adults with documented Hg exposure between 1970 and 1997. Oculo-visual examinations of 80 community members included visual acuity, automated visual fields, optical coherence tomography [OCT], color vision and contrast sensitivity. Median age was 57 years (IQR 51-63) and 55% of participants were women. Median visual acuity was 0.1 logMAR (Snellen 6/6.4; IQR 0-0.2). A total of 26% of participants presented a Visual Field Index inferior to 62%, and qualitative losses assessment showed concentric constriction (18%), end-stage concentric loss (18%), and complex defects (24%). On OCT, retinal nerve fiber layer scans showed 74% of participants within normal/green range. For color testing with the Hardy, Rand, and Rittler test, 40% presented at least one type of color defect, and with the Lanthony D-15 test, median color confusion index was 1.59 (IQR 1.33-1.96). Contrast sensitivity showed moderate loss for 83% of participants. These findings demonstrate important loss of visual field, color vision, and contrast sensitivity in older adults in a context of long-term exposure to Hg in Grassy Narrows First Nation.
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Affiliation(s)
- Benoit Tousignant
- School of Optometry, Université de Montréal, 3744 Jean-Brillant, Montreal, QC H3T 1P1, Canada
- Department of Social and Preventive Medicine, School of Public Health, Université de Montréal, 7101 Avenue du Parc, Montreal, QC H3N 1X9, Canada
| | - Annie Chatillon
- School of Optometry, Université de Montréal, 3744 Jean-Brillant, Montreal, QC H3T 1P1, Canada
| | - Aline Philibert
- Centre de Recherche Interdisciplinaire sur le Bien-être, la Santé, la Société et L’environnement (Cinbiose), Université du Québec à Montréal, C.P. 8888, Succ. Centre-Ville, Montréal, QC H3C 3P8, Canada
| | - Judy Da Silva
- Grassy Narrows First Nation, General Delivery, Grassy Narrows, ON P0X 1B0, Canada
| | - Myriam Fillion
- Centre de Recherche Interdisciplinaire sur le Bien-être, la Santé, la Société et L’environnement (Cinbiose), Université du Québec à Montréal, C.P. 8888, Succ. Centre-Ville, Montréal, QC H3C 3P8, Canada
- Département Science et Technologie, Université TÉLUQ, 5800, Rue Saint-Denis, Bureau 1105, Montréal, QC H2S 3L5, Canada
| | - Donna Mergler
- Centre de Recherche Interdisciplinaire sur le Bien-être, la Santé, la Société et L’environnement (Cinbiose), Université du Québec à Montréal, C.P. 8888, Succ. Centre-Ville, Montréal, QC H3C 3P8, Canada
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The distribution of toxic metals in the human retina and optic nerve head: Implications for age-related macular degeneration. PLoS One 2020; 15:e0241054. [PMID: 33119674 PMCID: PMC7595417 DOI: 10.1371/journal.pone.0241054] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2020] [Accepted: 10/07/2020] [Indexed: 01/14/2023] Open
Abstract
Objective Toxic metals are suspected to play a role in the pathogenesis of age-related macular degeneration. However, difficulties in detecting the presence of multiple toxic metals within the intact human retina, and in separating primary metal toxicity from the secondary uptake of metals in damaged tissue, have hindered progress in this field. We therefore looked for the presence of several toxic metals in the posterior segment of normal adult eyes using elemental bioimaging. Methods Paraffin sections of the posterior segment of the eye from seven tissue donors (age range 54–74 years) to an eye bank were examined for toxic metals in situ using laser ablation-inductively coupled plasma-mass spectrometry, a technique that detects multiple elements in tissues, as well as the histochemical technique of autometallography that demonstrates inorganic mercury, silver, and bismuth. No donor had a visual impairment, and no significant retinal abnormalities were seen on post mortem fundoscopy and histology. Results Metals found by laser ablation-inductively coupled plasma-mass spectrometry in the retinal pigment epithelium and choriocapillaris were lead (n = 7), nickel (n = 7), iron (n = 7), cadmium (n = 6), mercury (n = 6), bismuth (n = 5), aluminium (n = 3), and silver (n = 1). In the neural retina, mercury was present in six samples, and iron in one. Metals detected in the optic nerve head were iron (N = 7), mercury (N = 7), nickel (N = 4), and aluminium (N = 1). No gold or chromium was seen. Autometallography demonstrated probable inorganic mercury in the retinal pigment epithelium of one donor. Conclusion Several toxic metals are taken up by the human retina and optic nerve head. Injury to the retinal pigment epithelium from toxic metals could damage the neuroprotective functions of the retinal pigment epithelium and allow toxic metals to enter the outer neural retina. These findings support the hypothesis that accumulations of toxic metals in the retina could contribute to the pathogenesis of age-related macular degeneration.
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Mercury in the retina and optic nerve following prenatal exposure to mercury vapor. PLoS One 2019; 14:e0220859. [PMID: 31390377 PMCID: PMC6685637 DOI: 10.1371/journal.pone.0220859] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Accepted: 07/24/2019] [Indexed: 02/07/2023] Open
Abstract
Damage to the retina and optic nerve is found in some neurodegenerative disorders, but it is unclear whether the optic pathway and central nervous system (CNS) are affected by the same injurious agent, or whether optic pathway damage is due to retrograde degeneration following the CNS damage. Finding an environmental agent that could be responsible for the optic pathway damage would support the hypothesis that this environmental toxicant also triggers the CNS lesions. Toxic metals have been implicated in neurodegenerative disorders, and mercury has been found in the retina and optic nerve of experimentally-exposed animals. Therefore, to see if mercury exposure in the prenatal period could be one link between optic pathway damage and human CNS disorders of later life, we examined the retina and optic nerve of neonatal mice that had been exposed prenatally to mercury vapor, using a technique, autometallography, that detects the presence of mercury within cells. Pregnant mice were exposed to a non-toxic dose of mercury vapor for four hours a day for five days in late gestation, when the mouse placenta most closely resembles the human placenta. The neonatal offspring were sacrificed one day after birth and gapless serial sections of formalin-fixed paraffin-embedded blocks containing the eyes were stained with silver nitrate autometallography to detect inorganic mercury. Mercury was seen in the nuclear membranes of retinal ganglion cells and endothelial cells. A smaller amount of mercury was present in the retinal inner plexiform and inner nuclear layers. Mercury was conspicuous in the peripapillary retinal pigment epithelium. In the optic nerve, mercury was seen in the nuclear membranes and processes of glia and in endothelial cells. Optic pathway and CNS endothelial cells contained mercury. In conclusion, mercury is taken up preferentially by fetal retinal ganglion cells, optic nerve glial cells, the retinal pigment epithelium, and endothelial cells. Mercury induces free radical formation, autoimmunity, and genetic and epigenetic changes, so these findings raise the possibility that mercury plays a part in the pathogenesis of degenerative CNS disorders that also affect the retina and optic nerve.
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