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Kempuraj D, Mohan RR. Blast injury: Impact to the cornea. Exp Eye Res 2024:109915. [PMID: 38677709 DOI: 10.1016/j.exer.2024.109915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [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, Ukraine, etc. have increased the number of corneal and ocular disorders significantly 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 pathophysiology 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, Missouri, United States; One-Health Vision Research Program, Departments of Veterinary Medicine & Surgery and Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, Missouri, United States
| | - Rajiv R Mohan
- Harry S. Truman Memorial Veterans' Hospital, Columbia, Missouri, United States; One-Health Vision Research Program, Departments of Veterinary Medicine & Surgery and Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, Missouri, United States; Mason Eye Institute, School of Medicine, University of Missouri, Columbia, Missouri, United States.
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Navarro VM, Boehme N, Wasserman EA, Harper MM. Enhanced attention in rats following blast-induced traumatic brain injury. Heliyon 2024; 10:e25661. [PMID: 38384534 PMCID: PMC10878867 DOI: 10.1016/j.heliyon.2024.e25661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 01/30/2024] [Accepted: 01/31/2024] [Indexed: 02/23/2024] Open
Abstract
Purpose To evaluate visuo-cognitive sequelae following blast-induced traumatic brain injury in a rat model. Methods Rats were randomly assigned to one of four groups depending on the intensity/quantity of a blast received in a blast chamber: sham (no blast), low intensity (22 psi), medium intensity (26 psi), or three medium intensity blasts (26 psi × 3). After recovery, all subjects were given visual discrimination tasks of increasing complexity, until mastery. After behavioral training, visual function was assessed via spectral-domain optical coherence tomography and pattern electroretinogram, and the extent of retinal damage was quantified via immunohistochemistry of retinal ganglion cells. Results None of the measures assessing visual function revealed significant differences as a function of blast intensity/quantity. Behavioral training did not disclose short-term effects of blast in general motivation or the development of anticipatory responding. No differences in general learning ability and the number of perseverative errors were observed. However, behavioral training found effects of blast in attentional function; relative to controls, subjects that received blasts were faster in learning to attend to informative (over non-informative) cues in the most difficult visual discrimination task. Conclusion Blast exposure in rats resulted in increased attention following blast, with no appreciable deficits in visual function. These results are contrary to what is often reported for human clinical populations; as such, more research bridging methodological differences is necessary.
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Affiliation(s)
- Victor M. Navarro
- Cardiff University, Cardiff, Wales, United Kingdom
- The Iowa City Department of Veterans Affairs Medical Center, Center for the Prevention and Treatment of Visual Loss, Iowa City, IA, United States
| | - Nickolas Boehme
- The Iowa City Department of Veterans Affairs Medical Center, Center for the Prevention and Treatment of Visual Loss, Iowa City, IA, United States
- Department of Ophthalmology and Visual Sciences, The University of Iowa, Iowa City, IA, United States
| | - Edward A. Wasserman
- Department of Psychological and Brain Sciences, The University of Iowa, Iowa City, IA, United States
| | - Matthew M. Harper
- The Iowa City Department of Veterans Affairs Medical Center, Center for the Prevention and Treatment of Visual Loss, Iowa City, IA, United States
- Department of Ophthalmology and Visual Sciences, The University of Iowa, Iowa City, IA, United States
- Department of Biology, The University of Iowa, Iowa City, IA, United States
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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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Harper MM, Gramlich OW, Elwood BW, Boehme NA, Dutca LM, Kuehn MH. Immune responses in mice after blast-mediated traumatic brain injury TBI autonomously contribute to retinal ganglion cell dysfunction and death. Exp Eye Res 2022; 225:109272. [PMID: 36209837 DOI: 10.1016/j.exer.2022.109272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 09/21/2022] [Accepted: 09/25/2022] [Indexed: 02/04/2023]
Abstract
PURPOSE The purpose of this study was to examine the role of the immune system and its influence on chronic retinal ganglion cell (RGC) dysfunction following blast-mediated traumatic brain injury (bTBI). METHODS C57BL/6J and B6.129S7-Rag1tm1Mom/J (Rag-/-) mice were exposed to one blast injury of 140 kPa. A separate cohort of C57BL/6J mice was exposed to sham-blast. Four weeks following bTBI mice were euthanized, and splenocytes were collected. Adoptive transfer (AT) of splenocytes into naïve C57BL/6J recipient mice was accomplished via tail vein injection. Three groups of mice were analyzed: those receiving AT of splenocytes from C57BL/6J mice exposed to blast (AT-TBI), those receiving AT of splenocytes from C57BL/6J mice exposed to sham (AT-Sham), and those receiving AT of splenocytes from Rag-/- mice exposed to blast (AT-Rag-/-). The visual function of recipient mice was analyzed with the pattern electroretinogram (PERG), and the optomotor response (OMR). The structure of the retina was evaluated using optical coherence tomography (OCT), and histologically using BRN3A-antibody staining. RESULTS Analysis of the PERG showed a decreased amplitude two months post-AT that persisted for the duration of the study in AT-TBI mice. We also observed a significant decrease in the retinal thickness of AT-TBI mice two months post-AT compared to sham, but not at four or six months post-AT. The OMR response was significantly decreased in AT-TBI mice 5- and 6-months post-AT. BRN3A staining showed a loss of RGCs in AT-TBI and AT-Rag-/- mice. CONCLUSION These results suggest that the immune system contributes to chronic RGC dysfunction following bTBI.
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Affiliation(s)
- Matthew M Harper
- Departments of Ophthalmology and Visual Sciences, The University of Iowa, Iowa City, IA, USA; Departments of Biology, And Pharmacology, 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.
| | - Oliver W Gramlich
- Departments of Ophthalmology and Visual Sciences, The University of Iowa, Iowa City, IA, USA; Departments of Neuroscience and Pharmacology, 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
| | - Benjamin W Elwood
- Departments of Ophthalmology and Visual Sciences, 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
- Departments of Ophthalmology and Visual Sciences, 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
| | - Laura M Dutca
- Departments of Ophthalmology and Visual Sciences, 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
| | - Markus H Kuehn
- Departments of Ophthalmology and Visual Sciences, 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
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Harper MM, Boehme N, Dutca LM, Anderson MG. The Retinal Ganglion Cell Response to Blast-Mediated Traumatic Brain Injury Is Genetic Background Dependent. Invest Ophthalmol Vis Sci 2021; 62:13. [PMID: 34106210 PMCID: PMC8196410 DOI: 10.1167/iovs.62.7.13] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose The purpose of this study was to examine the influence of genetic background on the retinal ganglion cell (RGC) response to blast-mediated traumatic brain injury (TBI) in Jackson Diversity Outbred (J:DO), C57BL/6J and BALB/cByJ mice. Methods Mice were subject to one blast injury of 137 kPa. RGC structure was analyzed by optical coherence tomography (OCT), function by the pattern electroretinogram (PERG), and histologically using BRN3A antibody staining. Results Comparison of the change in each group from baseline for OCT and PERG was performed. There was a significant difference in the J:DOΔOCT compared to C57BL/6J mice (P = 0.004), but not compared to BALB/cByJ (P = 0.21). There was a significant difference in the variance of the ΔOCT in J:DO compared to both C57BL/6J and BALB/cByJ mice. The baseline PERG amplitude was 20.33 ± 9.32 µV, which decreased an average of −4.14 ± 12.46 µV following TBI. Baseline RGC complex + RNFL thickness was 70.92 ± 4.52 µm, which decreased an average of −1.43 ± 2.88 µm following blast exposure. There was not a significant difference in the ΔPERG between J:DO and C57BL/6J (P = 0.13), although the variances of the groups were significantly different. Blast exposure in J:DO mice results in a density change of 558.6 ± 440.5 BRN3A-positive RGCs/mm2 (mean ± SD). Conclusions The changes in retinal outcomes had greater variance in outbred mice than what has been reported, and largely replicated herein, for inbred mice. These results demonstrate that the RGC response to blast injury is highly dependent upon genetic background.
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Affiliation(s)
- Matthew M Harper
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, The University of Iowa, Iowa City, IA, United States.,Center for the Prevention and Treatment of Visual Loss, Iowa City VA Healthcare System, Department of Veterans Affairs, Iowa City, IA, United States
| | - Nickolas Boehme
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, The University of Iowa, Iowa City, IA, United States.,Center for the Prevention and Treatment of Visual Loss, Iowa City VA Healthcare System, Department of Veterans Affairs, Iowa City, IA, United States
| | - Laura M Dutca
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, The University of Iowa, Iowa City, IA, United States.,Center for the Prevention and Treatment of Visual Loss, Iowa City VA Healthcare System, Department of Veterans Affairs, Iowa City, IA, United States
| | - Michael G Anderson
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, The University of Iowa, Iowa City, IA, United States.,Center for the Prevention and Treatment of Visual Loss, Iowa City VA Healthcare System, Department of Veterans Affairs, Iowa City, IA, United States.,The Department of Molecular Physiology and Biophysics, Carver College of Medicine, The University of Iowa, Iowa City, IA, United States
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Axonopathy precedes cell death in ocular damage mediated by blast exposure. Sci Rep 2021; 11:11774. [PMID: 34083587 PMCID: PMC8175471 DOI: 10.1038/s41598-021-90412-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 05/04/2021] [Indexed: 12/13/2022] Open
Abstract
Traumatic brain injuries (TBI) of varied types are common across all populations and can cause visual problems. For military personnel in combat settings, injuries from blast exposures (bTBI) are prevalent and arise from a myriad of different situations. To model these diverse conditions, we are one of several groups modeling bTBI using mice in varying ways. Here, we report a refined analysis of retinal ganglion cell (RGC) damage in male C57BL/6J mice exposed to a blast-wave in an enclosed chamber. Ganglion cell layer thickness, RGC density (BRN3A and RBPMS immunoreactivity), cellular density of ganglion cell layer (hematoxylin and eosin staining), and axon numbers (paraphenylenediamine staining) were quantified at timepoints ranging from 1 to 17-weeks. RNA sequencing was performed at 1-week and 5-weeks post-injury. Earliest indices of damage, evident by 1-week post-injury, are a loss of RGC marker expression, damage to RGC axons, and increase in glial markers expression. Blast exposure caused a loss of RGC somas and axons—with greatest loss occurring by 5-weeks post-injury. While indices of glial involvement are prominent early, they quickly subside as RGCs are lost. The finding that axonopathy precedes soma loss resembles pathology observed in mouse models of glaucoma, suggesting similar mechanisms.
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