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Kempuraj D, Mohan RR. Blast injury: Impact to the cornea. Exp Eye Res 2024; 244:109915. [PMID: 38677709 PMCID: PMC11179966 DOI: 10.1016/j.exer.2024.109915] [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: 01/02/2024] [Revised: 04/03/2024] [Accepted: 04/24/2024] [Indexed: 04/29/2024]
Abstract
Visual disorders are common even after mild traumatic brain injury (mTBI) or blast exposure. The cost of blast-induced vision loss in civilians, military personnel, and veterans is significant. The visual consequences of blasts associated with TBI are elusive. Active military personnel and veterans report various ocular pathologies including corneal disorders post-combat blasts. The wars and conflicts in Afghanistan, Iraq, Syria, and Ukraine have significantly increased the number of corneal and other ocular disorders among military personnel and veterans. Binocular vision, visual fields, and other visual functions could be impaired following blast-mediated TBI. Blast-associated injuries can cause visual disturbances, binocular system problems, and visual loss. About 25% of veterans exposed to blasts report corneal injury. Blast exposure induces corneal edema, corneal opacity, increased corneal thickness, damage of corneal epithelium, corneal abrasions, and stromal and endothelial abnormality including altered endothelial density, immune cell infiltration, corneal neovascularization, Descemet membrane rupture, and increased pain mediators in animal models and the blast-exposed military personnel including veterans. Immune response exacerbates blast-induced ocular injury. TBI is associated with dry eyes and pain in veterans. Subjects exposed to blasts that cause TBI should undergo immediate clinical visual and ocular examinations. Delayed visual care may lead to progressive vision loss, lengthening/impairing rehabilitation and ultimately may lead to permanent vision problems and blindness. Open-field blast exposure could induce corneal injuries and immune responses in the cornea. Further studies are warranted to understand corneal pathology after blast exposure. A review of current advancements in blast-induced corneal injury will help elucidate novel targets for potential therapeutic options. This review discusses the impact of blast exposure-associated corneal disorders.
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Affiliation(s)
- Duraisamy Kempuraj
- Harry S. Truman Memorial Veterans' Hospital, Columbia, MO, United States; One-Health Vision Research Program, Departments of Veterinary Medicine & Surgery and Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, MO, United States
| | - Rajiv R Mohan
- Harry S. Truman Memorial Veterans' Hospital, Columbia, MO, United States; One-Health Vision Research Program, Departments of Veterinary Medicine & Surgery and Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, MO, United States; Mason Eye Institute, School of Medicine, University of Missouri, Columbia, MO, United States.
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Pang JJ. The Variety of Mechanosensitive Ion Channels in Retinal Neurons. Int J Mol Sci 2024; 25:4877. [PMID: 38732096 PMCID: PMC11084373 DOI: 10.3390/ijms25094877] [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: 02/27/2024] [Revised: 04/16/2024] [Accepted: 04/20/2024] [Indexed: 05/13/2024] Open
Abstract
Alterations in intraocular and external pressure critically involve the pathogenesis of glaucoma, traumatic retinal injury (TRI), and other retinal disorders, and retinal neurons have been reported to express multiple mechanical-sensitive channels (MSCs) in recent decades. However, the role of MSCs in visual functions and pressure-related retinal conditions has been unclear. This review will focus on the variety and functional significance of the MSCs permeable to K+, Na+, and Ca2+, primarily including the big potassium channel (BK); the two-pore domain potassium channels TRAAK and TREK; Piezo; the epithelial sodium channel (ENaC); and the transient receptor potential channels vanilloid TRPV1, TRPV2, and TRPV4 in retinal photoreceptors, bipolar cells, horizontal cells, amacrine cells, and ganglion cells. Most MSCs do not directly mediate visual signals in vertebrate retinas. On the other hand, some studies have shown that MSCs can open in physiological conditions and regulate the activities of retinal neurons. While these data reasonably predict the crossing of visual and mechanical signals, how retinal light pathways deal with endogenous and exogenous mechanical stimulation is uncertain.
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Affiliation(s)
- Ji-Jie Pang
- Department of Ophthalmology, Baylor College of Medicine, Houston, TX 77030, USA
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Harper MM, Boehme NA, Dutca L, Navarro V. Increasing the number and intensity of shock tube generated blast waves leads to earlier retinal ganglion cell dysfunction and regional cell death. Exp Eye Res 2024; 239:109754. [PMID: 38113955 DOI: 10.1016/j.exer.2023.109754] [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: 07/25/2023] [Revised: 07/28/2023] [Accepted: 12/12/2023] [Indexed: 12/21/2023]
Abstract
The purpose of this study was to examine the effect of a blast exposure generated from a shock tube on retinal ganglion cell (RGC) function and structure. Mice were exposed to one of three blast conditions using a shock tube; a single blast wave of 20 PSI, a single blast wave of 30 PSI, or three blast waves of 30 PSI given on three consecutive days with a one-day inter-blast interval. The structure and function of the retina were analyzed using the pattern electroretinogram (PERG), the optomotor reflex (OMR), and optical coherence tomography (OCT). The in vivo parameters were examined at baseline, and then again 1-week, 4-weeks, and 16-weeks following blast exposure. The number of surviving RGCs was quantified at the end of the study. Analysis of mice receiving a 20 PSI injury showed decreased PERG and OMR responses 16-weeks post blast, without evidence of changed retinal thickness or RGC death. Mice subjected to a 30 PSI injury showed decreased PERG responses 4 weeks and 16 weeks after injury, without changes in the retinal thickness or RGC density. Mice subjected to 30 PSI X 3 blast exposures had PERG deficits 1-week and 4-weeks post exposure. There was also significant change in retinal thickness 1-week and 16-weeks post blast exposure. Mice receiving 30 PSI X 3 blast injuries had regional loss of RGCs in the central retina, but not in the mid-peripheral or peripheral retina. Overall, this study has shown that increasing the number of blast exposures and the intensity leads to earlier functional loss of RGCs. We have also shown regional RGC loss only when using the highest blast intensity and number of blast injuries.
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Affiliation(s)
- Matthew M Harper
- Department of Ophthalmology and Visual Sciences, The University of Iowa, Iowa City, IA, USA; Department of Biology, The University of Iowa, Iowa City, IA, USA; Veterans Administration Center for the Prevention and Treatment of Visual Loss, Iowa City VA Healthcare System, Iowa City, IA, USA.
| | - Nickolas A Boehme
- Veterans Administration Center for the Prevention and Treatment of Visual Loss, Iowa City VA Healthcare System, Iowa City, IA, USA
| | - Laura Dutca
- Veterans Administration Center for the Prevention and Treatment of Visual Loss, Iowa City VA Healthcare System, Iowa City, IA, USA
| | - Victor Navarro
- Veterans Administration Center for the Prevention and Treatment of Visual Loss, Iowa City VA Healthcare System, Iowa City, IA, USA
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Evaluating Ciliary Body Damage Induced by Blunt Low Speed Impact Using Finite Element Simulation. J Craniofac Surg 2022; 33:e355-e358. [DOI: 10.1097/scs.0000000000008089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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Evans LP, Roghair AM, Gilkes NJ, Bassuk AG. Visual Outcomes in Experimental Rodent Models of Blast-Mediated Traumatic Brain Injury. Front Mol Neurosci 2021; 14:659576. [PMID: 33935648 PMCID: PMC8081965 DOI: 10.3389/fnmol.2021.659576] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 03/18/2021] [Indexed: 11/24/2022] Open
Abstract
Blast-mediated traumatic brain injuries (bTBI) cause long-lasting physical, cognitive, and psychological disorders, including persistent visual impairment. No known therapies are currently utilized in humans to lessen the lingering and often serious symptoms. With TBI mortality decreasing due to advancements in medical and protective technologies, there is growing interest in understanding the pathology of visual dysfunction after bTBI. However, this is complicated by numerous variables, e.g., injury location, severity, and head and body shielding. This review summarizes the visual outcomes observed by various, current experimental rodent models of bTBI, and identifies data showing that bTBI activates inflammatory and apoptotic signaling leading to visual dysfunction. Pharmacologic treatments blocking inflammation and cell death pathways reported to alleviate visual deficits in post-bTBI animal models are discussed. Notably, techniques for assessing bTBI outcomes across exposure paradigms differed widely, so we urge future studies to compare multiple models of blast injury, to allow data to be directly compared.
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Affiliation(s)
- Lucy P. Evans
- Department of Pediatrics, University of Iowa, Iowa City, IA, United States
- Medical Scientist Training Program, University of Iowa, Iowa City, IA, United States
| | - Ariel M. Roghair
- Department of Pediatrics, University of Iowa, Iowa City, IA, United States
| | - Noah J. Gilkes
- Department of Pediatrics, University of Iowa, Iowa City, IA, United States
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Ríos JD, Hughes CK, Lally J, Wienandt N, Esquivel C, Serhan CN, Weitzel EK. Neuroprotectin D1 Attenuates Blast Overpressure Induced Reactive Microglial Cells in the Cochlea. Laryngoscope 2021; 131:E2018-E2025. [PMID: 33427310 DOI: 10.1002/lary.29337] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 12/02/2020] [Accepted: 12/08/2020] [Indexed: 12/31/2022]
Abstract
OBJECTIVE/HYPOTHESIS We examined a neuroinflammatory response associated with glial activation in the cochlea exposed to blast overpressure and evaluated the potential therapeutic efficacy of specialized pro-resolving mediators such as neuroprotectin D1, NPD1; (10R, 17S-dihydroxy-4Z, 7Z, 11E, 13E, 15Z, 19Z-docosahexaenoic acid) in a rodent blast-induced auditory injury model. STUDY DESIGN Animal Research. METHODS A compressed-air driven shock tube was used to expose anesthetized adult male Long-Evan rats to shock waves simulating an open-field blast exposure. Approximately 30 minutes after blast exposure, rats were treated with NPD1 (100 ng/kg body wt.) or vehicle delivered intravenously via tail vein injection. Rats were then euthanized 48 hours after blast exposure. Unexposed rats were included as controls. Tissue sections containing both middle and inner ear were prepared with hematoxylin-eosin staining to elucidate histopathological changes associated with blast exposure. Cochlear tissues were evaluated for relative expression of ionized calcium-binding adaptor 1 (Iba1), as an indicator of microglial activation by immunohistochemistry and western blot analyses. RESULTS Our animal model resulted in an acute injury mechanism manifested by damage to the tympanic membrane, hemorrhage, infiltration of inflammatory cells, and increased expression of Iba1 protein. Moreover, therapeutic intervention with NPD1 significantly reduced Iba1 expression in the cochlea, suggesting a reduction of a neuroinflammatory response caused by blast overpressure. CONCLUSIONS Blast overpressure resulted in an increased expression of proteins involved in gliosis within the auditory system, which were reduced by NPD1. Treatment of NPD1 suggests an effective strategy to reduce or halt auditory microglial cell activation due to primary blast exposure. LEVEL OF EVIDENCE NA Laryngoscope, 131:E2018-E2025, 2021.
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Affiliation(s)
- José David Ríos
- US Army Institute of Surgical Research, JBSA Fort Sam Houston, San Antonio, Texas, U.S.A
| | - Charlotte K Hughes
- US Army Institute of Surgical Research, JBSA Fort Sam Houston, San Antonio, Texas, U.S.A
| | - John Lally
- US Army Institute of Surgical Research, JBSA Fort Sam Houston, San Antonio, Texas, U.S.A
| | - Nathan Wienandt
- US Army Institute of Surgical Research, JBSA Fort Sam Houston, San Antonio, Texas, U.S.A
| | - Carlos Esquivel
- Department of Defense (DoD) Hearing Center of Excellence, Defense Health Agency, Joint Base San Antonio-Lackland, San Antonio, Texas, U.S.A
| | - Charles N Serhan
- Center for Experimental Therapeutics and Reperfusion Injury, Brigham and Women's Hospital and Department of Anesthesia, Perioperative and Pain Medicine, Harvard Medical School, Boston, Massachusetts, U.S.A
| | - Erik K Weitzel
- US Army Institute of Surgical Research, JBSA Fort Sam Houston, San Antonio, Texas, U.S.A.,Department of Defense (DoD) Hearing Center of Excellence, Defense Health Agency, Joint Base San Antonio-Lackland, San Antonio, Texas, U.S.A
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Arun P, Rossetti F, DeMar JC, Wang Y, Batuure AB, Wilder DM, Gist ID, Morris AJ, Sabbadini RA, Long JB. Antibodies Against Lysophosphatidic Acid Protect Against Blast-Induced Ocular Injuries. Front Neurol 2020; 11:611816. [PMID: 33384658 PMCID: PMC7769950 DOI: 10.3389/fneur.2020.611816] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 11/24/2020] [Indexed: 01/18/2023] Open
Abstract
Exposure to blast overpressure waves is implicated as the major cause of ocular injuries and resultant visual dysfunction in veterans involved in recent combat operations. No effective therapeutic strategies have been developed so far for blast-induced ocular dysfunction. Lysophosphatidic acid (LPA) is a bioactive phospholipid generated by activated platelets, astrocytes, choroidal plexus cells, and microglia and is reported to play major roles in stimulating inflammatory processes. The levels of LPA in the cerebrospinal fluid have been reported to increase acutely in patients with traumatic brain injury (TBI) as well as in a controlled cortical impact (CCI) TBI model in mice. In the present study, we have evaluated the efficacy of a single intravenous administration of a monoclonal LPA antibody (25 mg/kg) given at 1 h post-blast for protection against injuries to the retina and associated ocular dysfunctions. Our results show that a single 19 psi blast exposure significantly increased the levels of several species of LPA in blood plasma at 1 and 4 h post-blast. The anti-LPA antibody treatment significantly decreased glial cell activation and preserved neuronal cell morphology in the retina on day 8 after blast exposure. Optokinetic measurements indicated that anti-LPA antibody treatment significantly improved visual acuity in both eyes on days 2 and 6 post-blast exposure. Anti-LPA antibody treatment significantly increased rod photoreceptor and bipolar neuronal cell signaling in both eyes on day 7 post-blast exposure. These results suggest that blast exposure triggers release of LPAs, which play a major role promoting blast-induced ocular injuries, and that a single early administration of anti-LPA antibodies provides significant protection.
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Affiliation(s)
- Peethambaran Arun
- Blast-Induced Neurotrauma Branch, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Franco Rossetti
- Blast-Induced Neurotrauma Branch, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - James C DeMar
- Blast-Induced Neurotrauma Branch, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Ying Wang
- Blast-Induced Neurotrauma Branch, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Andrew B Batuure
- Blast-Induced Neurotrauma Branch, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Donna M Wilder
- Blast-Induced Neurotrauma Branch, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Irene D Gist
- Blast-Induced Neurotrauma Branch, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Andrew J Morris
- Division of Cardiovascular Medicine, Lexington VA Medical Center, College of Medicine, University of Kentucky, Lexington, KY, United States
| | - Roger A Sabbadini
- Department of Biology, San Diego State University, San Diego, CA, United States
| | - Joseph B Long
- Blast-Induced Neurotrauma Branch, Walter Reed Army Institute of Research, Silver Spring, MD, United States
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