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Okoyeocha EOM, Tewari-Singh N. Chloropicrin induced ocular injury: Biomarkers, potential mechanisms, and treatments. Toxicol Lett 2024; 396:70-80. [PMID: 38677567 DOI: 10.1016/j.toxlet.2024.04.006] [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: 10/24/2023] [Revised: 04/09/2024] [Accepted: 04/17/2024] [Indexed: 04/29/2024]
Abstract
Ocular tissue, especially the cornea, is overly sensitive to chemical exposures. The availability and adoption of chemical threat agent chloropicrin (CP) is growing in the United States as a pesticide and fumigant; thereby increasing the risk of its use in warfare, terrorist attacks and non-intentional exposure. Exposure to CP results in immediate ocular, respiratory, and dermal injury; however, we lack knowledge on its mechanism of toxicity as well as of its breakdown products like chlorine and phosgene, and effective therapies are elusive. Herein, we have reviewed the recent findings on exposure route, toxicity and likely mechanisms of CP induced ocular toxicity based on other vesicating chemical warfare agents that cause ocular injury. We have focused on the implication of their toxicity and mechanistic outcomes in the ocular tissue, especially the cornea, which could be useful in the development of broad-spectrum effective therapeutic options. We have discussed on the potential countermeasures, overall hallmarks and challenges involved in studying ocular injuries from chemical threat agent exposures. Finally, we reviewed useful available technologies and methods that can assist in the identification of effective medical countermeasures for chemical threat agents related ocular injuries.
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Affiliation(s)
- Ebenezar O M Okoyeocha
- Department of Pharmacology and Toxicology, College of Osteopathic Medicine, Michigan State University, East Lansing, MI, 48824, USA
| | - Neera Tewari-Singh
- Department of Pharmacology and Toxicology, College of Osteopathic Medicine, Michigan State University, East Lansing, MI, 48824, USA.
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Ebenezar OO, Roney A, Goswami DG, Petrash JM, Sledge D, Komáromy AM, Liby KT, Tewari-Singh N. Ocular injury progression and cornea histopathology from chloropicrin vapor exposure: Relevant clinical biomarkers in mice. Exp Eye Res 2023; 230:109440. [PMID: 36933694 DOI: 10.1016/j.exer.2023.109440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 03/13/2023] [Accepted: 03/16/2023] [Indexed: 03/18/2023]
Abstract
Ocular tissue is highly sensitive to chemical exposures. Chloropicrin (CP), a choking agent employed during World War I and currently a popular pesticide and fumigating agent, is a potential chemical threat agent. Accidental, occupational, or intentional exposure to CP results in severe ocular injury, especially to the cornea; however, studies on ocular injury progression and underlying mechanisms in a relevant in vivo animal model are lacking. This has impaired the development of effective therapies to treat the acute and long-term ocular toxicity of CP. To study the in vivo clinical and biological effects of CP ocular exposure, we tested different CP exposure doses and durations in mice. These exposures will aid in the study of acute ocular injury and its progression as well as identify a moderate dose to develop a relevant rodent ocular injury model with CP. The left eyes of male BALB/c mice were exposed to CP (20% CP for 0.5 or 1 min or 10% CP for 1 min) using a vapor cap, with the right eyes serving as controls. Injury progression was evaluated for 25 days post-exposure. CP-exposure caused a significant corneal ulceration and eyelid swelling which resolved by day 14 post exposure. In addition, CP-exposure caused significant corneal opacity and neovascularization. Development of hydrops (severe corneal edema with corneal bullae) and hyphema (blood accumulation in the anterior chamber) was observed as advanced CP effects. Mice were euthanized at day 25 post-CP-exposure, and the eyes were harvested to further study the corneal injury. Histopathological analyses showed a significant CP-induced decrease in corneal epithelial thickness and increased stromal thickness with more pronounced damage, including stromal fibrosis, edema, neovascularization, trapped epithelial cells, anterior and posterior synechiae, and infiltration of inflammatory cells. Loss of the corneal endothelial cells and Descemet's membrane could be associated with the CP-induced corneal edema and hydrops which could lead to long term term pathological conditions. Although exposure to 20% CP for 1 min caused more eyelid swelling, ulceration, and hyphema, similar effects were observed with all CP exposures. These novel findings following CP ocular exposure in a mouse model outline the corneal histopathologic changes that associate with the continuing ocular clinical effects. The data are useful in designing further studies to identify and correlate the clinical and biological markers of CP ocular injury progression with acute and long-term toxic effects on cornea and other ocular tissues. We take a crucial step towards CP ocular injury model development and in pathophysiological studies to identify molecular targets for therapeutic interventions.
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Affiliation(s)
- Okoyeocha Om Ebenezar
- Department of Pharmacology and Toxicology, College of Osteopathic Medicine, Michigan State University, East Lansing, MI, 48824, USA
| | - Andrew Roney
- Department of Pharmacology and Toxicology, College of Osteopathic Medicine, Michigan State University, East Lansing, MI, 48824, USA
| | - Dinesh G Goswami
- Department of Pharmacology and Toxicology, College of Osteopathic Medicine, Michigan State University, East Lansing, MI, 48824, USA
| | - J Mark Petrash
- Department of Ophthalmology, School of Medicine, University of Colorado-Anschutz Medical Campus, Aurora, CO, 80045, USA
| | - Dodd Sledge
- Michigan State University Veterinary Diagnostic Laboratory, East Lansing, MI, 48824, USA
| | - András M Komáromy
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI, 48824, USA
| | - Karen T Liby
- Department of Pharmacology and Toxicology, College of Osteopathic Medicine, Michigan State University, East Lansing, MI, 48824, USA
| | - Neera Tewari-Singh
- Department of Pharmacology and Toxicology, College of Osteopathic Medicine, Michigan State University, East Lansing, MI, 48824, USA.
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Joseph LB, Gordon MK, Zhou P, Hahn RA, Lababidi H, Croutch CR, Sinko PJ, Heck DE, Laskin DL, Laskin JD. Sulfur mustard corneal injury is associated with alterations in the epithelial basement membrane and stromal extracellular matrix. Exp Mol Pathol 2022; 128:104807. [PMID: 35798063 PMCID: PMC10044521 DOI: 10.1016/j.yexmp.2022.104807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 05/20/2022] [Accepted: 06/29/2022] [Indexed: 12/15/2022]
Abstract
Sulfur mustard (SM; bis(2-chloroethyl) sulfide) is a highly reactive bifunctional alkylating agent synthesized for chemical warfare. The eyes are particularly sensitive to SM where it causes irritation, pain, photophobia, and blepharitis, depending on the dose and duration of exposure. In these studies, we examined the effects of SM vapor on the corneas of New Zealand white male rabbits. Edema and hazing of the cornea, signs of acute injury, were observed within one day of exposure to SM, followed by neovascularization, a sign of chronic or late phase pathology, which persisted for at least 28 days. Significant epithelial-stromal separation ranging from ~8-17% of the epithelial surface was observed. In the stroma, there was a marked increase in CD45+ leukocytes and a decrease of keratocytes, along with areas of disorganization of collagen fibers. SM also disrupted the corneal basement membrane and altered the expression of perlecan, a heparan sulfate proteoglycan, and cellular fibronectin, an extracellular matrix glycoprotein. This was associated with an increase in basement membrane matrix metalloproteinases including ADAM17, which is important in remodeling of the basement membrane during wound healing. Tenascin-C, an extracellular matrix glycoprotein, was also upregulated in the stroma 14-28 d post SM, a finding consistent with its role in organizing structural components of the stroma necessary for corneal transparency. These data demonstrate that SM vapor causes persistent alterations in structural components of the cornea. Further characterization of SM-induced injury in rabbit cornea will be useful for the identification of targets for the development of ocular countermeasures.
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Affiliation(s)
- Laurie B Joseph
- Department of Pharmacology and Toxicology, Ernest Mario School of Pharmacy, Rutgers University, Piscataway, NJ 08854, United States of America.
| | - Marion K Gordon
- Department of Pharmacology and Toxicology, Ernest Mario School of Pharmacy, Rutgers University, Piscataway, NJ 08854, United States of America
| | - Peihong Zhou
- Department of Pharmacology and Toxicology, Ernest Mario School of Pharmacy, Rutgers University, Piscataway, NJ 08854, United States of America
| | - Rita A Hahn
- Department of Pharmacology and Toxicology, Ernest Mario School of Pharmacy, Rutgers University, Piscataway, NJ 08854, United States of America
| | - Hamdi Lababidi
- Department of Pharmacology and Toxicology, Ernest Mario School of Pharmacy, Rutgers University, Piscataway, NJ 08854, United States of America
| | | | - Patrick J Sinko
- Department of Pharmaceutical Science, Ernest Mario School of Pharmacy, Rutgers University, Piscataway, NJ 08854, United States of America
| | - Diane E Heck
- Department of Public Health, New York Medical College, Valhalla, NY 10595, United States of America
| | - Debra L Laskin
- Department of Pharmacology and Toxicology, Ernest Mario School of Pharmacy, Rutgers University, Piscataway, NJ 08854, United States of America
| | - Jeffrey D Laskin
- Department of Environmental and Occupational Health and Justice, Rutgers University School of Public Health, Piscataway, NJ 08854, United States of America
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Araj H, Tseng H, Yeung DT. Supporting discovery and development of medical countermeasures for chemical injury to eye and skin. Exp Eye Res 2022; 221:109156. [PMID: 35716762 DOI: 10.1016/j.exer.2022.109156] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 06/09/2022] [Accepted: 06/12/2022] [Indexed: 12/01/2022]
Abstract
Vesicants, from vesica (Latin for blister), can cause local and systemic toxicity. They include the chemotherapy drug nitrogen mustard and chemical warfare agents sulfur mustard, Lewisite, and phosgene oxime. These agents are commonly released in vapor form and consequently, eyes and skin are the most vulnerable. The ocular and cutaneous injuries can be acute, subacute, or chronic, and can predispose casualties to secondary deleterious effects. Underlying these broad organ responses are shared and tissue-specific cellular and molecular biological cascades that attempt to counteract such chemical injuries. Depending on the severity of the chemical insult, biological responses often lead to inadequate wound healing and result in long-term pathology instead. Exposure to other toxic industrial chemicals such as acrolein, chloropicrin, and hydrogen fluoride, can also cause prominent eye and skin damage. There are currently no FDA-approved drugs to counteract these injuries. Hence, the possibility of a mass casualty emergency involving these chemicals is a major public health concern. Recognizing this critical challenge, the United States Department of Health and Human Services (HHS) is committed to the development of medical countermeasures to advance national health and medical preparedness against these highly toxic chemicals. Here, we provide an overview of various HHS funding and scientific opportunities available in this space, emphasizing parallels between eye and skin response to chemical injury. We also discuss a main limitation of existing data and suggest ways to overcome it.
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Affiliation(s)
- Houmam Araj
- Department of Health and Human Services, National Eye Institute/National Institutes of Health (NEI/NIH), 6700B Rockledge Drive, Bethesda, MD, 20817, United States.
| | - Hung Tseng
- Department of Health and Human Services, National Institute of Arthritis & Musculoskeletal & Skin Diseases/National Institutes of Health (NIAMS/NIH), 6701 Democracy Boulevard, Bethesda, MD, 20892, United States.
| | - David T Yeung
- Department of Health and Human Services, National Institute of Allergy and Infectious Diseases/National Institutes of Health (NIAID/NIH), 5601 Fishers Lane, Bethesda, MD, 20892, United States.
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