Jayme Hentig, PhD, MBA, MPH(c)

Abstract: Traumatic brain injuries (TBI) and posttraumatic stress disorder (PTSD) are commonly observed comorbid occurrences among military service members and veterans (SMVs). In this cross-sectional study, SMVs with a history of TBI were stratified into symptomatic and asymptomatic PTSD groups based on posttraumatic stress checklist-civilian (PCL-C) total scores. Blood-based biomarkers were assessed, and significant differential markers were associated with scores from multiple… Show more

Abstract: Traumatic brain injuries (TBI) and posttraumatic stress disorder (PTSD) are commonly observed comorbid occurrences among military service members and veterans (SMVs). In this cross-sectional study, SMVs with a history of TBI were stratified into symptomatic and asymptomatic PTSD groups based on posttraumatic stress checklist-civilian (PCL-C) total scores. Blood-based biomarkers were assessed, and significant differential markers were associated with scores from multiple neurobehavioral self-report assessments. PCL-C cutoffs were total scores >50 (PTSD symptomatic) and <25 (asymptomatic). Cytokines IL6, IL8, TNFα, and IL10 were significantly elevated (p < 0.05–0.001) in the TBI+/PTSD symptomatic group compared to the TBI+/asymptomatic group. Cytokine levels of IL8, TNFα, and IL10 were strongly associated with PCL-C scores (0.356 < r > 0.624 for all, p < 0.01 for all), while TNFα and IL10 were additionally associated with NSI totals (r = 0.285 and r = 0.270, p < 0.05, respectively). This is the first study focused on PTSD symptom severity to report levels of circulating pro-inflammatory IL8, specifically in SMVs with TBI. These data suggest that within the military TBI population, there are unique cytokine profiles that relate to neurobehavioral outcomes associated with TBI and PTSD.
Keywords: military; TBI; cytokines; IL-8; PTSD; inflammation Show less

Abstract: As a predominately young, physically active, and generally healthy population, service members (SMs) with vestibular dysfunction (VD) following TBI may not be accurately represented by cur-rent civilian reference ranges on assessments of VD. This study enrolled SMs who were referred for vestibular rehabilitation following mild/moderate TBI. Participants self-reported VD by Ac-tivities Balance Confidence (ABC) and Dizziness Handicap Inventory (DHI) followed by evalua-tion of vestibular… Show more

Abstract: As a predominately young, physically active, and generally healthy population, service members (SMs) with vestibular dysfunction (VD) following TBI may not be accurately represented by cur-rent civilian reference ranges on assessments of VD. This study enrolled SMs who were referred for vestibular rehabilitation following mild/moderate TBI. Participants self-reported VD by Ac-tivities Balance Confidence (ABC) and Dizziness Handicap Inventory (DHI) followed by evalua-tion of vestibular performance by Computerized Dynamic Posturography-Sensory Organization-al Test (CDP-SOT). Retrospective analysis of these outcomes comparing the study sample of SMs to reported civilian samples revealed SMs self-reported lower VD with significantly higher bal-ance confidence (ABC: 77.11 ± 14.61, p<0.05) and lower dizziness (DHI: 37.75 ± 11.74, p<0.05) than civilians. However, SMs underperformed in performance-based evaluations compared to civilians with significantly lower CDP-SOT composite and ratio scores (COMP: 68.46 ± 13.46, p<0.05, VIS: 81.36 ± 14.03, p<0.01, VEST: 55.63 ± 22.28, p<0.05, SOM: 90.46 ± 10.17, p<0.05). Cor-relational analyses identified significant relationships between ABC and CDP-SOT composite (r=0.380, p<0.01) and ratios (VIS: r=0.266, p<0.05, VEST: r=0.352, p<0.01). These results highlight the importance of recognizing and understanding nuances in assessing VD in SMs to ensure they have access to adequate care and rehabilitation prior to returning to duty. Show less

Repetitive low-level blast exposure is one of the major occupational health concerns among US military service members and law enforcement. This study seeks to identify gene expression using microRNA and RNA sequencing in whole-blood samples from experienced breachers and unexposed controls. We performed experimental RNA sequencing using Illumina’s HiSeq 2500 Sequencing System, and microRNA analysis using NanoString Technology nCounter miRNA expression panel in whole-blood total RNA samples… Show more

Repetitive low-level blast exposure is one of the major occupational health concerns among US military service members and law enforcement. This study seeks to identify gene expression using microRNA and RNA sequencing in whole-blood samples from experienced breachers and unexposed controls. We performed experimental RNA sequencing using Illumina’s HiSeq 2500 Sequencing System, and microRNA analysis using NanoString Technology nCounter miRNA expression panel in whole-blood total RNA samples from 15 experienced breachers and 14 age-, sex-, and race-matched unexposed controls. We identified 10 significantly dysregulated genes between experienced breachers and unexposed controls, with FDR corrected <0.05: One upregulated gene, LINC00996 (long intergenic non-protein coding RNA 996); and nine downregulated genes, IGLV3-16 (immunoglobulin lambda variable 3-16), CD200 (CD200 molecule), LILRB5 (leukocyte immunoglobulin-like receptor B5), ZNF667-AS1 (ZNF667 antisense RNA 1), LMOD1 (leiomodin 1), CNTNAP2 (contactin-associated protein 2), EVPL (envoplakin), DPF3 (double PHD fingers 3), and IGHV4-34 (immunoglobulin heavy variable 4-34). The dysregulated gene expressions reported here have been associated with chronic inflammation and immune response, suggesting that these pathways may relate to the risk of lasting neurological symptoms following high exposures to blast over a career. Show less

Approximately 2 million individuals experience a traumatic brain injury (TBI) every year in the United States. Secondary injury begins within minutes after TBI, with alterations in cellular function and chemical signaling that contribute to excitotoxicity. Post-traumatic seizures (PTS) are experienced in an increasing number of TBI individuals that also display resistance to traditional anti-seizure medications (ASMs). Sonic hedgehog (Shh) is a signaling pathway that is upregulated following… Show more

Approximately 2 million individuals experience a traumatic brain injury (TBI) every year in the United States. Secondary injury begins within minutes after TBI, with alterations in cellular function and chemical signaling that contribute to excitotoxicity. Post-traumatic seizures (PTS) are experienced in an increasing number of TBI individuals that also display resistance to traditional anti-seizure medications (ASMs). Sonic hedgehog (Shh) is a signaling pathway that is upregulated following central nervous system damage in zebrafish and aids injury-induced regeneration. Using a modified Marmarou weight drop on adult zebrafish, we examined PTS following TBI and Shh modulation. We found that inhibiting Shh signaling by cyclopamine significantly increased PTS in TBI fish, prolonged the timeframe PTS was observed, and decreased survival across all TBI severities. Shh-inhibited TBI fish failed to respond to traditional ASMs, but were attenuated when treated with CNQX, which blocks ionotropic glutamate receptors. We found that the Smoothened agonist, purmorphamine, increased Eaat2a expression in undamaged brains compared to untreated controls, and purmorphamine treatment reduced glutamate excitotoxicity following TBI. Similarly, purmorphamine reduced PTS, edema, and cognitive deficits in TBI fish, while these pathologies were increased and/or prolonged in cyclopamine-treated TBI fish. However, the increased severity of TBI phenotypes with cyclopamine was reduced by cotreating fish with ceftriaxone, which induces Eaat2a expression. Collectively, these data suggest that Shh signaling induces Eaat2a expression and plays a role in regulating TBI-induced glutamate excitotoxicity and TBI sequelae. Show less

Traumatic brain injury (TBI)-related hospitalizations, disabilities, and mortalities have continued to rise over the last two decades affecting both military and civilian populations. These injuries can result in short- and long-term consequences and have been linked to increased rates of neurodegenerative disorders. However, humans possess adult neurogenesis, albeit very restricted and limited. Nevertheless, humans therefore have the potential for regenerative recovery, although little is… Show more

Traumatic brain injury (TBI)-related hospitalizations, disabilities, and mortalities have continued to rise over the last two decades affecting both military and civilian populations. These injuries can result in short- and long-term consequences and have been linked to increased rates of neurodegenerative disorders. However, humans possess adult neurogenesis, albeit very restricted and limited. Nevertheless, humans therefore have the potential for regenerative recovery, although little is known about human progenitor abundance or capacity to produce a diverse neural linage. In contrast, zebrafish possess a robust regenerative capacity shown to respond to trauma across both the peripheral and central nervous systems. This novel study proposes the use of a modified blunt-force TBI in the adult zebrafish to further examine a wide range of injury- induced pathologies, as well to further elucidate the regenerative mechanisms harbored by the zebrafish towards functional recovery. This study extensively characterizes a plethora of TBI-pathologies across mild, moderate, and severe TBI. This study then
describes the regenerative response temporally and spatially in response to TBI. Finally, this study describes the mechanism by which Shh signaling pathway can be leveraged as a prophylactic treatment increasing Eaat2a expression and reducing TBI-sequelae by regulating glutamate excitotoxicity. Collectively, this study provides a foundation for future studies in blunt-force TBI sequelae progression and in injury-induced neuronal regeneration in the adult zebrafish. Show less

Full Authors List: Dilorom Sass, Vivian De Alvarenga Guedes, Ethan Smith, Rany Vorn, Christina Devoto, Katie Edwards, Sara Mithani, James Hentig, Chen Lai, Chelsea Wagner, Kerri Dunbar, David Hyde, Leorey Saligan, Michael J Roy and Jessica Mary Gill

Contribution to the field
Traumatic brain injury (TBI) affects millions of Americans each year. Yet, in chronic TBI research, few studies have examined the relationship between biological sex, circulating biomarkers of TBI, and… Show more

Full Authors List: Dilorom Sass, Vivian De Alvarenga Guedes, Ethan Smith, Rany Vorn, Christina Devoto, Katie Edwards, Sara Mithani, James Hentig, Chen Lai, Chelsea Wagner, Kerri Dunbar, David Hyde, Leorey Saligan, Michael J Roy and Jessica Mary Gill

Contribution to the field
Traumatic brain injury (TBI) affects millions of Americans each year. Yet, in chronic TBI research, few studies have examined the relationship between biological sex, circulating biomarkers of TBI, and behavioral symptoms and quality of life. To address this gap in the literature, we measured plasma levels of glial fibrillary acidic protein (GFAP), total tau, and neurofilament light chain in men and women with chronic TBI, and analyzed the relationship between these proteins and subjective measures of post-concussive symptoms, depression, post-traumatic stress disorder, and quality of life. We show that compared to men, woman have higher levels of tau and GFAP. We also show that women have higher measures of post-concussive symptoms and depressive symptoms, and lower quality of life scores. Importantly, our findings indicate that in women higher biomarker levels correlate with higher post-concussive symptoms, while higher biomarker levels correlate with lower levels of physical and social functioning. We did not observe these trends in men. Here, we provide evidence suggesting that circulating TBI biomarkers differ based on sex and may relate to behavior symptoms and quality of life. Our study advances the field forward by identifying potential TBI biomarkers stratified by sex, which could lead to novel opportunities for personalized treatments. Show less

Blunt-force traumatic brain injury (TBI) affects an increasing number of people worldwide as the range of injury severity and heterogeneity of injury pathologies have been recognized. Most current damage models utilize non-regenerative organisms, less common TBI mechanisms (penetrating, chemical, blast), and are limited in scalability of injury severity. We describe a scalable blunt-force TBI model that exhibits a wide range of human clinical pathologies and allows studying both injury… Show more

Blunt-force traumatic brain injury (TBI) affects an increasing number of people worldwide as the range of injury severity and heterogeneity of injury pathologies have been recognized. Most current damage models utilize non-regenerative organisms, less common TBI mechanisms (penetrating, chemical, blast), and are limited in scalability of injury severity. We describe a scalable blunt-force TBI model that exhibits a wide range of human clinical pathologies and allows studying both injury pathology/progression and mechanisms of regenerative recovery. We modified the Marmarou weight drop model for adult zebrafish, which delivers a scalable injury spanning mild, moderate, and severe phenotypes. Following injury, zebrafish display a wide range of severity-dependent, injury-induced pathologies, including seizures, blood brain barrier disruption, neuroinflammation, edema, vascular injury, decreased recovery rate, neuronal cell death, sensorimotor difficulties, and cognitive deficits. Injury-induced pathologies rapidly dissipate 4-7 days post-injury as robust cell proliferation is observed across the neuroaxis. In the cerebellum, proliferating nestin:GFP-positive cells originated from the cerebellar crest by 60 hours post-injury, which then infiltrated into the granule cell layer and differentiated into neurons. Shh pathway genes increased in expression shortly following injury. Injection of the Shh agonist purmorphamine in undamaged fish induced a significant proliferative response, while the proliferative response was inhibited in injured fish treated with cyclopamine, a Shh antagonist. Collectively, these data demonstrate that a scalable blunt-force TBI to adult zebrafish results in many pathologies similar to human TBI, followed by recovery, and neuronal regeneration in a Shh-dependent manner. Show less

Abstract: Cognitive deficits, including impaired learning and memory, are a primary symptom of various developmental and age-related neurodegenerative diseases and traumatic brain injury (TBI). Zebrafish are an important neuroscience model due to their transparency during development and robust regenerative capabilities following neurotrauma. While various cognitive tests exist in zebrafish, most of the cognitive assessments that are rapid examine non-associative learning. At the same time… Show more

Abstract: Cognitive deficits, including impaired learning and memory, are a primary symptom of various developmental and age-related neurodegenerative diseases and traumatic brain injury (TBI). Zebrafish are an important neuroscience model due to their transparency during development and robust regenerative capabilities following neurotrauma. While various cognitive tests exist in zebrafish, most of the cognitive assessments that are rapid examine non-associative learning. At the same time, associative-learning assays often require multiple days or weeks. Here, we describe a rapid associative-learning test that utilizes an adverse stimulus (electric shock) and requires minimal preparation time. The shuttle box assay, presented here, is simple, ideal for novice investigators, and requires minimal equipment. We demonstrate that, following TBI, this shuttle box test reproducibly assesses cognitive deficit and recovery from young to old zebrafish. Additionally, the assay is adaptable to examine either immediate or delayed memory. We demonstrate that both a single TBI and repeated TBI events negatively affect learning and immediate memory but not delayed memory. We, therefore, conclude that the shuttle box assay reproducibly tracks the progression and recovery of cognitive impairment. Show less

Abstract: Blunt-force traumatic brain injuries (TBI) are the most common form of head trauma, which spans a range of severities and results in complex and heterogenous secondary effects. While there is no mechanism to replace or regenerate the lost neurons following a TBI in humans, zebrafish possess the ability to regenerate neurons throughout their body, including the brain. To examine the breadth of pathologies exhibited in zebrafish following a blunt-force TBI and to study the mechanisms… Show more

Abstract: Blunt-force traumatic brain injuries (TBI) are the most common form of head trauma, which spans a range of severities and results in complex and heterogenous secondary effects. While there is no mechanism to replace or regenerate the lost neurons following a TBI in humans, zebrafish possess the ability to regenerate neurons throughout their body, including the brain. To examine the breadth of pathologies exhibited in zebrafish following a blunt-force TBI and to study the mechanisms underlying the subsequent neuronal regenerative response, we modified the commonly used rodent Marmarou weight drop for the use in adult zebrafish. Our simple blunt-force TBI model is scalable, inducing a mild, moderate, or severe TBI, and recapitulates many of the phenotypes observed following human TBI, such as contact- and post-traumatic seizures, edema, subdural and intracerebral hematomas, and cognitive impairments, each displayed in an injury severity-dependent manner. TBI sequelae, which begin to appear within minutes of the injury, subside and return to near undamaged control levels within 7 days post-injury. The regenerative process begins as early as 48 hours post-injury (hpi), with the peak cell proliferation observed by 60 hpi. Thus, our zebrafish blunt-force TBI model produces characteristic primary and secondary injury TBI pathologies similar to human TBI, which allows for investigating disease onset and progression, along with the mechanisms of neuronal regeneration that is unique to zebrafish. Show less

Zinc sulfate is a known olfactory toxicant, although its specific effects on the olfactory epithelium of zebrafish are unknown. Olfactory organs of adult zebrafish were exposed to zinc sulfate and, after 2, 3, 5, 7, 10 or 14 days, fish were processed for histological, immunohistochemical, ultrastructural, and behavioral analyses. Severe morphological disruption of the olfactory organ was observed two days following zinc sulfate exposure, including fusion of lamellae, epithelial inflammation… Show more

Zinc sulfate is a known olfactory toxicant, although its specific effects on the olfactory epithelium of zebrafish are unknown. Olfactory organs of adult zebrafish were exposed to zinc sulfate and, after 2, 3, 5, 7, 10 or 14 days, fish were processed for histological, immunohistochemical, ultrastructural, and behavioral analyses. Severe morphological disruption of the olfactory organ was observed two days following zinc sulfate exposure, including fusion of lamellae, epithelial inflammation, and significant loss of anti-calretinin labeling. Scanning electron microscopy revealed the apical surface of the sensory region was absent of ciliated structures, but microvilli were still present. Behavioral analysis showed significant loss of the ability to perceive bile salts and some fish also had no response to amino acids. Over the next several days, olfactory organ morphology, epithelial structure, and anti-calretinin labeling returned to control-like conditions, although the ability to perceive bile salts remained lost until day 14. Thus, exposure to zinc sulfate results in rapid degeneration of the olfactory organ, followed by restoration of morphology and function within two weeks. Zinc sulfate appears to have a greater effect on ciliated olfactory sensory neurons than on microvillous olfactory sensory neurons, suggesting differential effects on sensory neuron subtypes.
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