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Chu E, Mychasiuk R, Green TRF, Zamani A, Dill LK, Sharma R, Raftery AL, Tsantikos E, Hibbs ML, Semple BD. Regulation of microglial responses after pediatric traumatic brain injury: exploring the role of SHIP-1. Front Neurosci 2023; 17:1276495. [PMID: 37901420 PMCID: PMC10603304 DOI: 10.3389/fnins.2023.1276495] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2023] [Accepted: 09/18/2023] [Indexed: 10/31/2023] Open
Abstract
Introduction Severe traumatic brain injury (TBI) is the world's leading cause of permanent neurological disability in children. TBI-induced neurological deficits may be driven by neuroinflammation post-injury. Abnormal activity of SH2 domain-containing inositol 5' phosphatase-1 (SHIP-1) has been associated with dysregulated immunological responses, but the role of SHIP-1 in the brain remains unclear. The current study investigated the immunoregulatory role of SHIP-1 in a mouse model of moderate-severe pediatric TBI. Methods SHIP-1+/- and SHIP-1-/- mice underwent experimental TBI or sham surgery at post-natal day 21. Brain gene expression was examined across a time course, and immunofluorescence staining was evaluated to determine cellular immune responses, alongside peripheral serum cytokine levels by immunoassays. Brain tissue volume loss was measured using volumetric analysis, and behavior changes both acutely and chronically post-injury. Results Acutely, inflammatory gene expression was elevated in the injured cortex alongside increased IBA-1 expression and altered microglial morphology; but to a similar extent in SHIP-1-/- mice and littermate SHIP-1+/- control mice. Similarly, the infiltration and activation of CD68-positive macrophages, and reactivity of GFAP-positive astrocytes, was increased after TBI but comparable between genotypes. TBI increased anxiety-like behavior acutely, whereas SHIP-1 deficiency alone reduced general locomotor activity. Chronically, at 12-weeks post-TBI, SHIP-1-/- mice exhibited reduced body weight and increased circulating cytokines. Pro-inflammatory gene expression in the injured hippocampus was also elevated in SHIP-1-/- mice; however, GFAP immunoreactivity at the injury site in TBI mice was lower. TBI induced a comparable loss of cortical and hippocampal tissue in both genotypes, while SHIP-1-/- mice showed reduced general activity and impaired working memory, independent of TBI. Conclusion Together, evidence does not support SHIP-1 as an essential regulator of brain microglial morphology, brain immune responses, or the extent of tissue damage after moderate-severe pediatric TBI in mice. However, our data suggest that reduced SHIP-1 activity induces a greater inflammatory response in the hippocampus chronically post-TBI, warranting further investigation.
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Affiliation(s)
- Erskine Chu
- Department of Neuroscience, Monash University, Melbourne, VIC, Australia
- Department of Immunology, Monash University, Melbourne, VIC, Australia
| | - Richelle Mychasiuk
- Department of Neuroscience, Monash University, Melbourne, VIC, Australia
- Deparment of Neurology, Alfred Health, Prahran, VIC, Australia
| | - Tabitha R. F. Green
- Department of Integrative Physiology, The University of Colorado Boulder, Boulder, CO, United States
| | - Akram Zamani
- Department of Neuroscience, Monash University, Melbourne, VIC, Australia
| | - Larissa K. Dill
- Department of Neuroscience, Monash University, Melbourne, VIC, Australia
- Alfred Health, Prahran, VIC, Australia
| | - Rishabh Sharma
- Department of Neuroscience, Monash University, Melbourne, VIC, Australia
| | - April L. Raftery
- Department of Immunology, Monash University, Melbourne, VIC, Australia
| | - Evelyn Tsantikos
- Department of Immunology, Monash University, Melbourne, VIC, Australia
| | - Margaret L. Hibbs
- Department of Immunology, Monash University, Melbourne, VIC, Australia
| | - Bridgette D. Semple
- Department of Neuroscience, Monash University, Melbourne, VIC, Australia
- Deparment of Neurology, Alfred Health, Prahran, VIC, Australia
- Department of Medicine (Royal Melbourne Hospital), The University of Melbourne, Parkville, VIC, Australia
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Leung WL, Dill LK, Perucca P, O'Brien TJ, Casillas-Espinosa PM, Semple BD. Inherent Susceptibility to Acquired Epilepsy in Selectively Bred Rats Influences the Acute Response to Traumatic Brain Injury. J Neurotrauma 2023; 40:2174-2192. [PMID: 37221897 DOI: 10.1089/neu.2022.0463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023] Open
Abstract
Traumatic brain injury (TBI) often causes seizures associated with a neuroinflammatory response and neurodegeneration. TBI responses may be influenced by differences between individuals at a genetic level, yet this concept remains understudied. Here, we asked whether inherent differences in one's vulnerability to acquired epilepsy would determine acute physiological and neuroinflammatory responses acutely after experimental TBI, by comparing selectively bred "seizure-prone" (FAST) rats with "seizure-resistant" (SLOW) rats, as well as control parental strains (Long Evans and Wistar rats). Eleven-week-old male rats received a moderate-to-severe lateral fluid percussion injury (LFPI) or sham surgery. Rats were assessed for acute injury indicators and neuromotor performance, and blood was serially collected. At 7 days post-injury, brains were collected for quantification of tissue atrophy by cresyl violet (CV) histology, and immunofluorescent staining of activated inflammatory cells. FAST rats showed an exacerbated physiological response acutely post-injury, with a 100% seizure rate and mortality within 24 h. Conversely, SLOW rats showed no acute seizures and a more rapid neuromotor recovery compared with controls. Brains from SLOW rats also showed only modest immunoreactivity for microglia/macrophages and astrocytes in the injured hemisphere compared with controls. Further, group differences were apparent between the control strains, with greater neuromotor deficits observed in Long Evans rats compared with Wistars post-TBI. Brain-injured Long Evans rats also showed the most pronounced inflammatory response to TBI across multiple brain regions, whereas Wistar rats showed the greatest extent of regional brain atrophy. These findings indicate that differential genetic predisposition to develop acquired epilepsy (i.e., FAST vs. SLOW rat strains) determines acute responses after experimental TBI. Differences in the neuropathological response to TBI between commonly used control rat strains is also a novel finding, and an important consideration for future study design. Our results support further investigation into whether genetic predisposition to acute seizures predicts the chronic outcomes after TBI, including the development of post-traumatic epilepsy.
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Affiliation(s)
- Wai Lam Leung
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, Victoria, Australia
| | - Larissa K Dill
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, Victoria, Australia
- Department of Neurology, Alfred Health, Melbourne, Victoria, Australia
- The Perron Institute for Neurological and Translational Science, Nedlands, Western Australia, Australia
| | - Piero Perucca
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, Victoria, Australia
- Department of Neurology, Alfred Health, Melbourne, Victoria, Australia
- Epilepsy Research Centre, Department of Medicine (Austin Health), The University of Melbourne, Heidelberg, Victoria, Australia
- Bladin-Berkovic Comprehensive Epilepsy Program, Department of Neurology, Austin Health, Heidelberg, Victoria, Australia
- Department of Neurology, The Royal Melbourne Hospital, Parkville, Victoria, Australia
| | - Terence J O'Brien
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, Victoria, Australia
- Department of Neurology, Alfred Health, Melbourne, Victoria, Australia
- Department of Neurology, The Royal Melbourne Hospital, Parkville, Victoria, Australia
- Department of Medicine (Royal Melbourne Hospital), The University of Melbourne, Parkville, Victoria, Australia
| | - Pablo M Casillas-Espinosa
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, Victoria, Australia
- Department of Neurology, Alfred Health, Melbourne, Victoria, Australia
- Department of Medicine (Royal Melbourne Hospital), The University of Melbourne, Parkville, Victoria, Australia
| | - Bridgette D Semple
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, Victoria, Australia
- Department of Neurology, Alfred Health, Melbourne, Victoria, Australia
- Department of Medicine (Royal Melbourne Hospital), The University of Melbourne, Parkville, Victoria, Australia
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Chu E, Mychasiuk R, Tsantikos E, Raftery AL, L’Estrange-Stranieri E, Dill LK, Semple BD, Hibbs ML. Regulation of Microglial Signaling by Lyn and SHIP-1 in the Steady-State Adult Mouse Brain. Cells 2023; 12:2378. [PMID: 37830592 PMCID: PMC10571795 DOI: 10.3390/cells12192378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 09/21/2023] [Accepted: 09/26/2023] [Indexed: 10/14/2023] Open
Abstract
Chronic neuroinflammation and glial activation are associated with the development of many neurodegenerative diseases and neuropsychological disorders. Recent evidence suggests that the protein tyrosine kinase Lyn and the lipid phosphatase SH2 domain-containing inositol 5' phosphatase-1 (SHIP-1) regulate neuroimmunological responses, but their homeostatic roles remain unclear. The current study investigated the roles of Lyn and SHIP-1 in microglial responses in the steady-state adult mouse brain. Young adult Lyn-/- and SHIP-1-/- mice underwent a series of neurobehavior tests and postmortem brain analyses. The microglial phenotype and activation state were examined by immunofluorescence and flow cytometry, and neuroimmune responses were assessed using gene expression analysis. Lyn-/- mice had an unaltered behavioral phenotype, neuroimmune response, and microglial phenotype, while SHIP-1-/- mice demonstrated reduced explorative activity and exhibited microglia with elevated activation markers but reduced granularity. In addition, expression of several neuroinflammatory genes was increased in SHIP-1-/- mice. In response to LPS stimulation ex vivo, the microglia from both Lyn-/- and SHIP-1-/- showed evidence of hyper-activity with augmented TNF-α production. Together, these findings demonstrate that both Lyn and SHIP-1 have the propensity to control microglial responses, but only SHIP-1 regulates neuroinflammation and microglial activation in the steady-state adult brain, while Lyn activity appears dispensable for maintaining brain homeostasis.
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Affiliation(s)
- Erskine Chu
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC 3004, Australia
- Department of Immunology, Central Clinical School, Monash University, Melbourne, VIC 3004, Australia; (E.T.); (A.L.R.); (E.L.-S.)
| | - Richelle Mychasiuk
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC 3004, Australia
- Department of Neurology, Alfred Health, Melbourne, VIC 3004, Australia
| | - Evelyn Tsantikos
- Department of Immunology, Central Clinical School, Monash University, Melbourne, VIC 3004, Australia; (E.T.); (A.L.R.); (E.L.-S.)
| | - April L. Raftery
- Department of Immunology, Central Clinical School, Monash University, Melbourne, VIC 3004, Australia; (E.T.); (A.L.R.); (E.L.-S.)
| | - Elan L’Estrange-Stranieri
- Department of Immunology, Central Clinical School, Monash University, Melbourne, VIC 3004, Australia; (E.T.); (A.L.R.); (E.L.-S.)
| | - Larissa K. Dill
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC 3004, Australia
| | - Bridgette D. Semple
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC 3004, Australia
- Department of Neurology, Alfred Health, Melbourne, VIC 3004, Australia
- Department of Medicine, The Royal Melbourne Hospital, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Margaret L. Hibbs
- Department of Immunology, Central Clinical School, Monash University, Melbourne, VIC 3004, Australia; (E.T.); (A.L.R.); (E.L.-S.)
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Dill LK, Teymornejad S, Sharma R, Bozkurt S, Christensen J, Chu E, Rewell SS, Shad A, Mychasiuk R, Semple BD. Modulating chronic outcomes after pediatric traumatic brain injury: Distinct effects of social and environmental enrichment. Exp Neurol 2023; 364:114407. [PMID: 37059414 DOI: 10.1016/j.expneurol.2023.114407] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 03/16/2023] [Accepted: 04/11/2023] [Indexed: 04/16/2023]
Abstract
Impairments in social and cognitive function are a common consequence of pediatric traumatic brain injury (TBI). Rehabilitation has the potential to promote optimal behavioral recovery. Here, we evaluated whether an enhanced social and/or cognitive environment could improve long-term outcomes in a preclinical model of pediatric TBI. Male C57Bl/6 J mice received a moderately-severe TBI or sham procedure at postnatal day 21. After one week, mice were randomized to different social conditions (minimal socialization, n = 2/cage; or social grouping, n = 6/cage), and housing conditions (standard cage, or environmental enrichment (EE), incorporating sensory, motor, and cognitive stimuli). After 8 weeks, neurobehavioral outcomes were assessed, followed by post-mortem neuropathology. We found that TBI mice exhibited hyperactivity, spatial memory deficits, reduced anxiety-like behavior, and reduced sensorimotor performance compared to age-matched sham controls. Pro-social and sociosexual behaviors were also reduced in TBI mice. EE increased sensorimotor performance, and the duration of sociosexual interactions. Conversely, social housing reduced hyperactivity and altered anxiety-like behavior in TBI mice, and reduced same-sex social investigation. TBI mice showed impaired spatial memory retention, except for TBI mice exposed to both EE and group housing. In the brain, while TBI led to significant regional tissue atrophy, social housing had modest neuroprotective effects on hippocampal volumes, neurogenesis, and oligodendrocyte progenitor numbers. In conclusion, manipulation of the post-injury environment has benefit for chronic behavioral outcomes, but the benefits are specific to the type of enrichment available. This study improves understanding of modifiable factors that may be harnessed to optimize long-term outcomes for survivors of early-life TBI.
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Affiliation(s)
- Larissa K Dill
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC 3004, Australia; Department of Neurology, Alfred Health, Melbourne, VIC 3004, Australia; The Perron Institute for Neurological and Translational Science, Nedlands, WA 6009, Australia
| | - Sadaf Teymornejad
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC 3004, Australia
| | - Rishabh Sharma
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC 3004, Australia
| | - Salome Bozkurt
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC 3004, Australia
| | - Jennaya Christensen
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC 3004, Australia
| | - Erskine Chu
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC 3004, Australia
| | - Sarah S Rewell
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC 3004, Australia
| | - Ali Shad
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC 3004, Australia; Department of Neurology, Alfred Health, Melbourne, VIC 3004, Australia
| | - Richelle Mychasiuk
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC 3004, Australia; Department of Neurology, Alfred Health, Melbourne, VIC 3004, Australia
| | - Bridgette D Semple
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC 3004, Australia; Department of Neurology, Alfred Health, Melbourne, VIC 3004, Australia; Department of Medicine (Royal Melbourne Hospital), The University of Melbourne, Parkville, VIC 3050, Australia.
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Sharma R, Chu E, Dill LK, Shad A, Zamani A, O'Brien TJ, Casillas-Espinosa PM, Shultz SR, Semple BD. Ccr2 Gene Ablation Does Not Influence Seizure Susceptibility, Tissue Damage, or Cellular Inflammation after Murine Pediatric Traumatic Brain Injury. J Neurotrauma 2023; 40:365-382. [PMID: 36070444 DOI: 10.1089/neu.2022.0033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Pediatric traumatic brain injury (TBI) is a major public health issue, and a risk factor for the development of post-traumatic epilepsy that may profoundly impact the quality of life for survivors. As the majority of neurotrauma research is focused on injury to the adult brain, our understanding of the developing brain's response to TBI remains incomplete. Neuroinflammation is an influential pathophysiological mechanism in TBI, and is thought to increase neuronal hyperexcitability, rendering the brain more susceptible to the onset of seizures and/or epileptogenesis. We here hypothesized that peripheral blood-derived macrophages, recruited into the injured brain via C-C motif ligand 2 (CCL2) chemokine/C-C chemokine receptor type 2 (CCR2) signaling, contributes to neuroinflammation and thus seizure susceptibility after experimental pediatric TBI. Using Ccr2 gene-deficient mice in the controlled cortical impact (CCI) model of TBI, in 3-week-old male mice we found that TBI led to an increase in susceptibility to pentylenetetrazol (PTZ)-evoked seizures, associated with considerable cortical tissue loss, a robust cellular neuroinflammatory response, and oxidative stress. Intriguingly, although Ccr2-deficiency increased CCL2 levels in serum, it did not exacerbate seizure susceptibility or the neuroinflammatory cellular response after pediatric TBI. Similarly, acute post-injury treatment with a CCR2 antagonist did not influence seizure susceptibility or the extent of tissue damage in wild-type (WT) mice. Together, our findings suggest that CCR2 is not a crucial driver of epileptogenesis or neuroinflammation after TBI in the developing brain. We propose that age may be an important factor differentiating our findings from previous studies in which targeting CCL2/CCR2 has been reported to be anti-inflammatory, neuroprotective or anti-seizure.
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Affiliation(s)
- Rishabh Sharma
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, Victoria, Australia
| | - Erskine Chu
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, Victoria, Australia
| | - Larissa K Dill
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, Victoria, Australia
- Department of Neurology, Alfred Health, Prahran, Victoria, Australia
| | - Ali Shad
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, Victoria, Australia
- Department of Neurology, Alfred Health, Prahran, Victoria, Australia
| | - Akram Zamani
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, Victoria, Australia
- Department of Neurology, Alfred Health, Prahran, Victoria, Australia
| | - Terence J O'Brien
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, Victoria, Australia
- Department of Neurology, Alfred Health, Prahran, Victoria, Australia
- Department of Medicine (Royal Melbourne Hospital), The University of Melbourne, Parkville, Victoria, Australia
| | - Pablo M Casillas-Espinosa
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, Victoria, Australia
- Department of Medicine (Royal Melbourne Hospital), The University of Melbourne, Parkville, Victoria, Australia
| | - Sandy R Shultz
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, Victoria, Australia
- Department of Neurology, Alfred Health, Prahran, Victoria, Australia
- Department of Medicine (Royal Melbourne Hospital), The University of Melbourne, Parkville, Victoria, Australia
| | - Bridgette D Semple
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, Victoria, Australia
- Department of Neurology, Alfred Health, Prahran, Victoria, Australia
- Department of Medicine (Royal Melbourne Hospital), The University of Melbourne, Parkville, Victoria, Australia
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Shultz SR, Shah AD, Huang C, Dill LK, Schittenhelm RB, Morganti-Kossmann MC, Semple BD. Temporal proteomics of human cerebrospinal fluid after severe traumatic brain injury. J Neuroinflammation 2022; 19:291. [PMID: 36482407 PMCID: PMC9730674 DOI: 10.1186/s12974-022-02654-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Accepted: 11/21/2022] [Indexed: 12/13/2022] Open
Abstract
The pathophysiology of traumatic brain injury (TBI) requires further characterization to fully elucidate changes in molecular pathways. Cerebrospinal fluid (CSF) provides a rich repository of brain-associated proteins. In this retrospective observational study, we implemented high-resolution mass spectrometry to evaluate changes to the CSF proteome after severe TBI. 91 CSF samples were analyzed with mass spectrometry, collected from 16 patients with severe TBI (mean 32 yrs; 81% male) on day 0, 1, 2, 4, 7 and/or 10 post-injury (8-16 samples/timepoint) and compared to CSF obtained from 11 non-injured controls. We quantified 1152 proteins with mass spectrometry, of which approximately 80% were associated with CSF. 1083 proteins were differentially regulated after TBI compared to control samples. The most highly-upregulated proteins at each timepoint included neutrophil elastase, myeloperoxidase, cathepsin G, matrix metalloproteinase-8, and S100 calcium-binding proteins A8, A9 and A12-all proteins involved in neutrophil activation, recruitment, and degranulation. Pathway enrichment analysis confirmed the robust upregulation of proteins associated with innate immune responses. Conversely, downregulated pathways included those involved in nervous system development, and several proteins not previously identified after TBI such as testican-1 and latrophilin-1. We also identified 7 proteins (GM2A, Calsyntenin 1, FAT2, GANAB, Lumican, NPTX1, SFRP2) positively associated with an unfavorable outcome at 6 months post-injury. Together, these findings highlight the robust innate immune response that occurs after severe TBI, supporting future studies to target neutrophil-related processes. In addition, the novel proteins we identified to be differentially regulated by severe TBI warrant further investigation as potential biomarkers of brain damage or therapeutic targets.
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Affiliation(s)
- Sandy R. Shultz
- grid.1002.30000 0004 1936 7857Department of Neuroscience, Monash University, Melbourne, VIC Australia ,grid.267362.40000 0004 0432 5259Alfred Health, Prahran, VIC Australia ,grid.1008.90000 0001 2179 088XDepartment of Medicine (Royal Melbourne Hospital), The University of Melbourne, Parkville, VIC Australia ,grid.267756.70000 0001 2183 6550Health and Human Services, Vancouver Island University, Nanaimo, Canada
| | - Anup D. Shah
- grid.1002.30000 0004 1936 7857Monash Proteomics and Metabolomics Facility, Monash University, Clayton, VIC Australia ,grid.1002.30000 0004 1936 7857Monash Bioinformatics Platform, Monash University, Clayton, VIC Australia
| | - Cheng Huang
- grid.1002.30000 0004 1936 7857Monash Proteomics and Metabolomics Facility, Monash University, Clayton, VIC Australia
| | - Larissa K. Dill
- grid.1002.30000 0004 1936 7857Department of Neuroscience, Monash University, Melbourne, VIC Australia ,grid.267362.40000 0004 0432 5259Alfred Health, Prahran, VIC Australia ,grid.482226.80000 0004 0437 5686The Perron Institute for Neurological and Translational Science, Nedlands, WA 6009 Australia
| | - Ralf B. Schittenhelm
- grid.1002.30000 0004 1936 7857Monash Proteomics and Metabolomics Facility, Monash University, Clayton, VIC Australia
| | - M. Cristina Morganti-Kossmann
- grid.1002.30000 0004 1936 7857Department of Epidemiology & Preventive Medicine, Monash University, Prahran, VIC Australia ,grid.427785.b0000 0001 0664 3531Department of Child Health, Barrow Neurological Institute at Phoenix Children’s Hospital, Phoenix, AZ USA ,grid.134563.60000 0001 2168 186XUniversity of Arizona College of Medicine, Phoenix, AZ USA
| | - Bridgette D. Semple
- grid.1002.30000 0004 1936 7857Department of Neuroscience, Monash University, Melbourne, VIC Australia ,grid.267362.40000 0004 0432 5259Alfred Health, Prahran, VIC Australia ,grid.1008.90000 0001 2179 088XDepartment of Medicine (Royal Melbourne Hospital), The University of Melbourne, Parkville, VIC Australia
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Sharma R, Casillas-Espinosa PM, Dill LK, Rewell SSJ, Hudson MR, O'Brien TJ, Shultz SR, Semple BD. Pediatric traumatic brain injury and a subsequent transient immune challenge independently influenced chronic outcomes in male mice. Brain Behav Immun 2022; 100:29-47. [PMID: 34808288 DOI: 10.1016/j.bbi.2021.11.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2021] [Revised: 10/27/2021] [Accepted: 11/15/2021] [Indexed: 01/30/2023] Open
Abstract
Traumatic brain injury (TBI) is a major contributor to death and disability worldwide. Children are at particularly high risk of both sustaining a TBI and experiencing serious long-term consequences, such as cognitive deficits, mental health problems and post-traumatic epilepsy. Severe TBI patients are highly susceptible to nosocomial infections, which are mostly acquired within the first week of hospitalization post-TBI. Yet the potential chronic impact of such acute infections following pediatric TBI remains unclear. In this study, we hypothesized that a peripheral immune challenge, such as lipopolysaccharide (LPS)-mimicking a hospital-acquired infection-would worsen inflammatory, neurobehavioral, and seizure outcomes after experimental pediatric TBI. To test this, three-week old male C57Bl/6J mice received a moderate controlled cortical impact or sham surgery, followed by 1 mg/kg i.p. LPS (or 0.9% saline vehicle) at 4 days TBI. Mice were randomized to four groups; sham-saline, sham-LPS, TBI-saline or TBI-LPS (n = 15/group). Reduced general activity and increased anxiety-like behavior were observed within 24 h in LPS-treated mice, indicating a transient sickness response. LPS-treated mice also exhibited a reduction in body weights, which persisted chronically. From 2 months post-injury, mice underwent a battery of tests for sensorimotor, cognitive, and psychosocial behaviors. TBI resulted in hyperactivity and spatial memory deficits, independent of LPS; whereas LPS resulted in subtle deficits in spatial memory retention. At 5 months post-injury, video-electroencephalographic recordings were obtained to evaluate both spontaneous seizure activity as well as the evoked seizure response to pentylenetetrazol (PTZ). TBI increased susceptibility to PTZ-evoked seizures; whereas LPS appeared to increase the incidence of spontaneous seizures. Post-mortem analyses found that TBI, but not LPS, resulted in robust glial reactivity and loss of cortical volume. A TBI × LPS interaction in hippocampal volume suggested that TBI-LPS mice had a subtle increase in ipsilateral hippocampus tissue loss; however, this was not reflected in neuronal cell counts. Both TBI and LPS independently had modest effects on chronic hippocampal gene expression. Together, contrary to our hypothesis, we observed minimal synergy between TBI and LPS. Instead, pediatric TBI and a subsequent transient immune challenge independently influenced chronic outcomes. These findings have implications for future preclinical modeling as well as acute post-injury patient management.
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Affiliation(s)
- Rishabh Sharma
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia
| | - Pablo M Casillas-Espinosa
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia; Department of Neurology, Alfred Health, Prahran, VIC, Australia; Department of Medicine (Royal Melbourne Hospital), The University of Melbourne, Parkville, VIC, Australia
| | - Larissa K Dill
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia; Department of Neurology, Alfred Health, Prahran, VIC, Australia
| | - Sarah S J Rewell
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia; Department of Neurology, Alfred Health, Prahran, VIC, Australia
| | - Matthew R Hudson
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia
| | - Terence J O'Brien
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia; Department of Neurology, Alfred Health, Prahran, VIC, Australia; Department of Medicine (Royal Melbourne Hospital), The University of Melbourne, Parkville, VIC, Australia
| | - Sandy R Shultz
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia; Department of Neurology, Alfred Health, Prahran, VIC, Australia; Department of Medicine (Royal Melbourne Hospital), The University of Melbourne, Parkville, VIC, Australia
| | - Bridgette D Semple
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia; Department of Neurology, Alfred Health, Prahran, VIC, Australia; Department of Medicine (Royal Melbourne Hospital), The University of Melbourne, Parkville, VIC, Australia.
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Retamal JS, Grace MS, Dill LK, Ramirez-Garcia P, Peng S, Gondin AB, Bennetts F, Alvi S, Rajasekhar P, Almazi JG, Carbone SE, Bunnett NW, Davis TP, Veldhuis NA, Poole DP, McIntyre P. Serotonin-induced vascular permeability is mediated by transient receptor potential vanilloid 4 in the airways and upper gastrointestinal tract of mice. J Transl Med 2021; 101:851-864. [PMID: 33859334 PMCID: PMC8047529 DOI: 10.1038/s41374-021-00593-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 03/12/2021] [Accepted: 03/14/2021] [Indexed: 01/07/2023] Open
Abstract
Endothelial and epithelial cells form physical barriers that modulate the exchange of fluid and molecules. The integrity of these barriers can be influenced by signaling through G protein-coupled receptors (GPCRs) and ion channels. Serotonin (5-HT) is an important vasoactive mediator of tissue edema and inflammation. However, the mechanisms that drive 5-HT-induced plasma extravasation are poorly defined. The Transient Receptor Potential Vanilloid 4 (TRPV4) ion channel is an established enhancer of signaling by GPCRs that promote inflammation and endothelial barrier disruption. Here, we investigated the role of TRPV4 in 5-HT-induced plasma extravasation using pharmacological and genetic approaches. Activation of either TRPV4 or 5-HT receptors promoted significant plasma extravasation in the airway and upper gastrointestinal tract of mice. 5-HT-mediated extravasation was significantly reduced by pharmacological inhibition of the 5-HT2A receptor subtype, or with antagonism or deletion of TRPV4, consistent with functional interaction between 5-HT receptors and TRPV4. Inhibition of receptors for the neuropeptides substance P (SP) or calcitonin gene-related peptide (CGRP) diminished 5-HT-induced plasma extravasation. Supporting studies assessing treatment of HUVEC with 5-HT, CGRP, or SP was associated with ERK phosphorylation. Exposure to the TRPV4 activator GSK1016790A, but not 5-HT, increased intracellular Ca2+ in these cells. However, 5-HT pre-treatment enhanced GSK1016790A-mediated Ca2+ signaling, consistent with sensitization of TRPV4. The functional interaction was further characterized in HEK293 cells expressing 5-HT2A to reveal that TRPV4 enhances the duration of 5-HT-evoked Ca2+ signaling through a PLA2 and PKC-dependent mechanism. In summary, this study demonstrates that TRPV4 contributes to 5-HT2A-induced plasma extravasation in the airways and upper GI tract, with evidence supporting a mechanism of action involving SP and CGRP release.
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Affiliation(s)
- Jeffri S Retamal
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
- ARC Centre of Excellence in Convergent Bio-Nano Science & Technology, Monash University, Parkville, VIC, Australia
| | - Megan S Grace
- School of Medical Sciences and Health Innovations Research Institute, RMIT University, Bundoora, VIC, Australia
- Department of Physiology, School of Medicine Nursing and Health Sciences, Monash University, Clayton, VIC, Australia
- Baker IDI Heart and Diabetes Institute, Melbourne, VIC, Australia
- School of Clinical Medicine, Faculty of Medicine, University of Queensland, Brisbane, QLD, Australia
| | - Larissa K Dill
- School of Medical Sciences and Health Innovations Research Institute, RMIT University, Bundoora, VIC, Australia
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia
| | - Paulina Ramirez-Garcia
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
- ARC Centre of Excellence in Convergent Bio-Nano Science & Technology, Monash University, Parkville, VIC, Australia
| | - Scott Peng
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
- ARC Centre of Excellence in Convergent Bio-Nano Science & Technology, Monash University, Parkville, VIC, Australia
| | - Arisbel B Gondin
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
- ARC Centre of Excellence in Convergent Bio-Nano Science & Technology, Monash University, Parkville, VIC, Australia
| | - Felix Bennetts
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Sadia Alvi
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Pradeep Rajasekhar
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
- ARC Centre of Excellence in Convergent Bio-Nano Science & Technology, Monash University, Parkville, VIC, Australia
| | - Juhura G Almazi
- School of Medical Sciences and Health Innovations Research Institute, RMIT University, Bundoora, VIC, Australia
| | - Simona E Carbone
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
- ARC Centre of Excellence in Convergent Bio-Nano Science & Technology, Monash University, Parkville, VIC, Australia
| | - Nigel W Bunnett
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
- ARC Centre of Excellence in Convergent Bio-Nano Science & Technology, Monash University, Parkville, VIC, Australia
- Department of Molecular Pathobiology, New York University College of Dentistry, New York, NY, USA
| | - Thomas P Davis
- ARC Centre of Excellence in Convergent Bio-Nano Science & Technology, Monash University, Parkville, VIC, Australia
| | - Nicholas A Veldhuis
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia.
- ARC Centre of Excellence in Convergent Bio-Nano Science & Technology, Monash University, Parkville, VIC, Australia.
| | - Daniel P Poole
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia.
- ARC Centre of Excellence in Convergent Bio-Nano Science & Technology, Monash University, Parkville, VIC, Australia.
| | - Peter McIntyre
- School of Medical Sciences and Health Innovations Research Institute, RMIT University, Bundoora, VIC, Australia
- The Florey Institute of Neuroscience and Mental Health, Parkville, VIC, Australia
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9
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Fletcher JL, Dill LK, Wood RJ, Wang S, Robertson K, Murray SS, Zamani A, Semple BD. Corrigendum to "Acute treatment with TrkB agonist LM22A-4 confers neuroprotection and preserves myelin integrity in a mouse model of pediatric traumatic brain injury" [Experimental Neurology 339 (2021): 113652]. Exp Neurol 2021; 343:113790. [PMID: 34187696 DOI: 10.1016/j.expneurol.2021.113790] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Jessica L Fletcher
- Department of Anatomy and Neuroscience, University of Melbourne, Parkville, VIC, Australia
| | - Larissa K Dill
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia
| | - Rhiannon J Wood
- Department of Anatomy and Neuroscience, University of Melbourne, Parkville, VIC, Australia
| | - Sharon Wang
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia
| | - Kate Robertson
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia
| | - Simon S Murray
- Department of Anatomy and Neuroscience, University of Melbourne, Parkville, VIC, Australia
| | - Akram Zamani
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia
| | - Bridgette D Semple
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia.
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10
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Sharma R, Zamani A, Dill LK, Sun M, Chu E, Robinson MJ, O'Brien TJ, Shultz SR, Semple BD. A systemic immune challenge to model hospital-acquired infections independently regulates immune responses after pediatric traumatic brain injury. J Neuroinflammation 2021; 18:72. [PMID: 33731173 PMCID: PMC7968166 DOI: 10.1186/s12974-021-02114-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 02/16/2021] [Indexed: 11/10/2022] Open
Abstract
Background Traumatic brain injury (TBI) is a major cause of disability in young children, yet the factors contributing to poor outcomes in this population are not well understood. TBI patients are highly susceptible to nosocomial infections, which are mostly acquired within the first week of hospitalization, and such infections may modify TBI pathobiology and recovery. In this study, we hypothesized that a peripheral immune challenge such as lipopolysaccharide (LPS)—mimicking a hospital-acquired infection—would worsen outcomes after experimental pediatric TBI, by perpetuating the inflammatory immune response. Methods Three-week-old male mice received either a moderate controlled cortical impact or sham surgery, followed by a single LPS dose (1 mg/kg i.p.) or vehicle (0.9% saline) at 4 days post-surgery, then analysis at 5 or 8 days post-injury (i.e., 1 or 4 days post-LPS). Results LPS-treated mice exhibited a time-dependent reduction in general activity and social investigation, and increased anxiety, alongside substantial body weight loss, indicating transient sickness behaviors. Spleen-to-body weight ratios were also increased in LPS-treated mice, indicative of persistent activation of adaptive immunity at 4 days post-LPS. TBI + LPS mice showed an impaired trajectory of weight gain post-LPS, reflecting a synergistic effect of TBI and the LPS-induced immune challenge. Flow cytometry analysis demonstrated innate immune cell activation in blood, brain, and spleen post-LPS; however, this was not potentiated by TBI. Cytokine protein levels in serum, and gene expression levels in the brain, were altered in response to LPS but not TBI across the time course. Immunofluorescence analysis of brain sections revealed increased glia reactivity due to injury, but no additive effect of LPS was observed. Conclusions Together, we found that a transient, infection-like systemic challenge had widespread effects on the brain and immune system, but these were not synergistic with prior TBI in pediatric mice. These findings provide novel insight into the potential influence of a secondary immune challenge to the injured pediatric brain, with future studies needed to elucidate the chronic effects of this two-hit insult. Supplementary Information The online version contains supplementary material available at 10.1186/s12974-021-02114-1.
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Affiliation(s)
- Rishabh Sharma
- Department of Neuroscience, Central Clinical School, Monash University, Level 6, The Alfred Centre, 99 Commercial Road, Melbourne, VIC, 3004, Australia
| | - Akram Zamani
- Department of Neuroscience, Central Clinical School, Monash University, Level 6, The Alfred Centre, 99 Commercial Road, Melbourne, VIC, 3004, Australia
| | - Larissa K Dill
- Department of Neuroscience, Central Clinical School, Monash University, Level 6, The Alfred Centre, 99 Commercial Road, Melbourne, VIC, 3004, Australia.,Department of Neurology, Alfred Health, Prahran, VIC, Australia
| | - Mujun Sun
- Department of Neuroscience, Central Clinical School, Monash University, Level 6, The Alfred Centre, 99 Commercial Road, Melbourne, VIC, 3004, Australia
| | - Erskine Chu
- Department of Neuroscience, Central Clinical School, Monash University, Level 6, The Alfred Centre, 99 Commercial Road, Melbourne, VIC, 3004, Australia
| | - Marcus J Robinson
- Department of Immunology and Pathology, Central Clinical School, Monash University, Melbourne, VIC, Australia
| | - Terence J O'Brien
- Department of Neuroscience, Central Clinical School, Monash University, Level 6, The Alfred Centre, 99 Commercial Road, Melbourne, VIC, 3004, Australia.,Department of Neurology, Alfred Health, Prahran, VIC, Australia.,Department of Medicine (Royal Melbourne Hospital), The University of Melbourne, Parkville, VIC, Australia
| | - Sandy R Shultz
- Department of Neuroscience, Central Clinical School, Monash University, Level 6, The Alfred Centre, 99 Commercial Road, Melbourne, VIC, 3004, Australia.,Department of Neurology, Alfred Health, Prahran, VIC, Australia.,Department of Medicine (Royal Melbourne Hospital), The University of Melbourne, Parkville, VIC, Australia
| | - Bridgette D Semple
- Department of Neuroscience, Central Clinical School, Monash University, Level 6, The Alfred Centre, 99 Commercial Road, Melbourne, VIC, 3004, Australia. .,Department of Neurology, Alfred Health, Prahran, VIC, Australia. .,Department of Medicine (Royal Melbourne Hospital), The University of Melbourne, Parkville, VIC, Australia.
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11
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Fletcher JL, Dill LK, Wood RJ, Wang S, Robertson K, Murray SS, Zamani A, Semple BD. Acute treatment with TrkB agonist LM22A-4 confers neuroprotection and preserves myelin integrity in a mouse model of pediatric traumatic brain injury. Exp Neurol 2021; 339:113652. [PMID: 33609501 DOI: 10.1016/j.expneurol.2021.113652] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Revised: 02/03/2021] [Accepted: 02/15/2021] [Indexed: 02/08/2023]
Abstract
Young children have a high risk of sustaining a traumatic brain injury (TBI), which can have debilitating life-long consequences. Importantly, the young brain shows particular vulnerability to injury, likely attributed to ongoing maturation of the myelinating nervous system at the time of insult. Here, we examined the effect of acute treatment with the partial tropomyosin receptor kinase B (TrkB) agonist, LM22A-4, on pathological and neurobehavioral outcomes after pediatric TBI, with the hypothesis that targeting TrkB would minimize tissue damage and support functional recovery. We focused on myelinated tracts-the corpus callosum and external capsules-based on recent evidence that TrkB activation potentiates oligodendrocyte remyelination. Male mice at postnatal day 21 received an experimental TBI or sham surgery. Acutely post-injury, extensive cell death, a robust glial response and disruption of compact myelin were evident in the injured brain. TBI or sham mice then received intranasal saline vehicle or LM22A-4 for 14 days. Behavior testing was performed from 4 weeks post-injury, and brains were collected at 5 weeks for histology. TBI mice showed hyperactivity, reduced anxiety-like behavior, and social memory impairments. LM22A-4 ameliorated the abnormal anxiolytic phenotype but had no effect on social memory deficits. Use of spectral confocal reflectance microscopy detected persistent myelin fragmentation in the external capsule of TBI mice at 5 weeks post-injury, which was accompanied by regionally distinct deficits in oligodendrocyte progenitor cells and post-mitotic oligodendrocytes, as well as chronic reactive gliosis and atrophy of the corpus callosum and injured external capsule. LM22A-4 treatment ameliorated myelin deficits in the perilesional external capsule, as well as tissue volume loss and the extent of reactive gliosis. However, there was no effect of this TrkB agonist on oligodendroglial populations detected at 5 weeks post-injury. Collectively, our results demonstrate that targeting TrkB immediately after TBI during early life confers neuroprotection and preserves myelin integrity, and this was associated with some improved neurobehavioral outcomes as the pediatric injured brain matures.
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Affiliation(s)
- Jessica L Fletcher
- Department of Anatomy and Neuroscience, University of Melbourne, Parkville, VIC, Australia
| | - Larissa K Dill
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia
| | - Rhiannon J Wood
- Department of Anatomy and Neuroscience, University of Melbourne, Parkville, VIC, Australia
| | - Sharon Wang
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia
| | - Kate Robertson
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia
| | - Simon S Murray
- Department of Anatomy and Neuroscience, University of Melbourne, Parkville, VIC, Australia
| | - Akram Zamani
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia
| | - Bridgette D Semple
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia; Department of Medicine (Royal Melbourne Hospital), The University of Melbourne, Parkville, VIC, Australia.
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12
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Ah Kim H, Semple BD, Dill LK, Pham L, Dworkin S, Zhang SR, Lim R, Sobey CG, McDonald SJ. Systemic treatment with human amnion epithelial cells after experimental traumatic brain injury. Brain Behav Immun Health 2020; 5:100072. [PMID: 34589854 PMCID: PMC8474600 DOI: 10.1016/j.bbih.2020.100072] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 04/13/2020] [Accepted: 04/16/2020] [Indexed: 10/26/2022] Open
Abstract
Systemic administration of human amnion epithelial cells (hAECs) was recently shown to reduce neuropathology and improve functional recovery following ischemic stroke in both mice and marmosets. Given the significant neuropathological overlap between ischemic stroke and traumatic brain injury (TBI), we hypothesized that a similar hAEC treatment regime would also improve TBI outcomes. Male mice (12 weeks old, n = 40) were given a sham injury or moderate severity TBI by controlled cortical impact. At 60 min post-injury, mice were given a single tail vein injection of either saline (vehicle) or 1 × 106 hAECs suspended in saline. At 24 h post-injury, mice were assessed for locomotion and anxiety using an open field, and sensorimotor ability using a rotarod. At 48 h post-injury, brains were collected for analysis of immune cells via flow cytometry, or histological evaluation of lesion volume and hAEC penetration. To assess the impact of TBI and hAECs on lymphoid organs, spleen and thymus weights were determined. Treatment with hAECs did not prevent TBI-induced sensorimotor deficits at 24 h post-injury. hAECs were detected in the injured brain parenchyma; however, lesion volume was not altered by hAEC treatment. Robust increases in several leukocyte populations in the ipsilateral hemisphere of TBI mice were found when compared to sham mice at 48 h post-injury; however, hAEC treatment did not alter brain immune cell numbers. Both TBI and hAEC treatment were found to increase spleen weight. Taken together, these findings indicate that-unlike in ischemic stroke-treatment with hAEC was unable to prevent immune cell infiltration and sensorimotor deficits in the acute stages following controlled cortical impact in mice. Although further investigations are required, our data suggests that the lack of hAEC-induced neuroprotection in the current study may be explained by the differential splenic contributions to neuropathology between these brain injury models.
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Affiliation(s)
- Hyun Ah Kim
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Bundoora, VIC, Australia
| | - Bridgette D Semple
- Department of Neuroscience, Monash University, Melbourne, VIC, Australia
| | - Larissa K Dill
- Department of Neuroscience, Monash University, Melbourne, VIC, Australia.,Alfred Health, Melbourne, VIC, Australia
| | - Louise Pham
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Bundoora, VIC, Australia
| | - Sebastian Dworkin
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Bundoora, VIC, Australia
| | - Shenpeng R Zhang
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Bundoora, VIC, Australia
| | - Rebecca Lim
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, VIC, Australia.,Department of Obstetrics and Gynecology, Monash University, Melbourne, VIC, Australia.,Australian Regenerative Medicine Institute, Monash University, Melbourne, VIC, Australia
| | - Christopher G Sobey
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Bundoora, VIC, Australia
| | - Stuart J McDonald
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Bundoora, VIC, Australia.,Department of Neuroscience, Monash University, Melbourne, VIC, Australia
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13
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Semple BD, Dill LK, O'Brien TJ. Immune Challenges and Seizures: How Do Early Life Insults Influence Epileptogenesis? Front Pharmacol 2020; 11:2. [PMID: 32116690 PMCID: PMC7010861 DOI: 10.3389/fphar.2020.00002] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 01/03/2020] [Indexed: 12/16/2022] Open
Abstract
The development of epilepsy, a process known as epileptogenesis, often occurs later in life following a prenatal or early postnatal insult such as cerebral ischemia, stroke, brain trauma, or infection. These insults share common pathophysiological pathways involving innate immune activation including neuroinflammation, which is proposed to play a critical role in epileptogenesis. This review provides a comprehensive overview of the latest preclinical evidence demonstrating that early life immune challenges influence neuronal hyperexcitability and predispose an individual to later life epilepsy. Here, we consider the range of brain insults that may promote the onset of chronic recurrent spontaneous seizures at adulthood, spanning intrauterine insults (e.g. maternal immune activation), perinatal injuries (e.g. hypoxic–ischemic injury, perinatal stroke), and insults sustained during early postnatal life—such as fever-induced febrile seizures, traumatic brain injuries, infections, and environmental stressors. Importantly, all of these insults represent, to some extent, an immune challenge, triggering innate immune activation and implicating both central and systemic inflammation as drivers of epileptogenesis. Increasing evidence suggests that pro-inflammatory cytokines such as interleukin-1 and subsequent signaling pathways are important mediators of seizure onset and recurrence, as well as neuronal network plasticity changes in this context. Our current understanding of how early life immune challenges prime microglia and astrocytes will be explored, as well as how developmental age is a critical determinant of seizure susceptibility. Finally, we will consider the paradoxical phenomenon of preconditioning, whereby these same insults may conversely provide neuroprotection. Together, an improved appreciation of the neuroinflammatory mechanisms underlying the long-term epilepsy risk following early life insults may provide insight into opportunities to develop novel immunological anti-epileptogenic therapeutic strategies.
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Affiliation(s)
- Bridgette D Semple
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia.,Department of Medicine, Royal Melbourne Hospital, The University of Melbourne, Parkville, VIC, Australia.,Department of Neurology, Alfred Health, Melbourne, VIC, Australia
| | - Larissa K Dill
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia.,Department of Neurology, Alfred Health, Melbourne, VIC, Australia
| | - Terence J O'Brien
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia.,Department of Medicine, Royal Melbourne Hospital, The University of Melbourne, Parkville, VIC, Australia.,Department of Neurology, Alfred Health, Melbourne, VIC, Australia
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