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Green TRF, Rowe RK. Quantifying microglial morphology: an insight into function. Clin Exp Immunol 2024; 216:221-229. [PMID: 38456795 PMCID: PMC11097915 DOI: 10.1093/cei/uxae023] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 01/17/2024] [Accepted: 03/06/2024] [Indexed: 03/09/2024] Open
Abstract
Microglia are specialized immune cells unique to the central nervous system (CNS). Microglia have a highly plastic morphology that changes rapidly in response to injury or infection. Qualitative and quantitative measurements of ever-changing microglial morphology are considered a cornerstone of many microglia-centric research studies. The distinctive morphological variations seen in microglia are a useful marker of inflammation and severity of tissue damage. Although a wide array of damage-associated microglial morphologies has been documented, the exact functions of these distinct morphologies are not fully understood. In this review, we discuss how microglia morphology is not synonymous with microglia function, however, morphological outcomes can be used to make inferences about microglial function. For a comprehensive examination of the reactive status of a microglial cell, both histological and genetic approaches should be combined. However, the importance of quality immunohistochemistry-based analyses should not be overlooked as they can succinctly answer many research questions.
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Affiliation(s)
- Tabitha R F Green
- Department of Integrative Physiology, The University of Colorado Boulder, Boulder, CO, USA
| | - Rachel K Rowe
- Department of Integrative Physiology, The University of Colorado Boulder, Boulder, CO, USA
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2
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Green TRF, Carey SD, Mannino G, Craig JA, Rowe RK, Zielinski MR. Sleep, inflammation, and hemodynamics in rodent models of traumatic brain injury. Front Neurosci 2024; 18:1361014. [PMID: 38426017 PMCID: PMC10903352 DOI: 10.3389/fnins.2024.1361014] [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] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2023] [Accepted: 01/29/2024] [Indexed: 03/02/2024] Open
Abstract
Traumatic brain injury (TBI) can induce dysregulation of sleep. Sleep disturbances include hypersomnia and hyposomnia, sleep fragmentation, difficulty falling asleep, and altered electroencephalograms. TBI results in inflammation and altered hemodynamics, such as changes in blood brain barrier permeability and cerebral blood flow. Both inflammation and altered hemodynamics, which are known sleep regulators, contribute to sleep impairments post-TBI. TBIs are heterogenous in cause and biomechanics, which leads to different molecular and symptomatic outcomes. Animal models of TBI have been developed to model the heterogeneity of TBIs observed in the clinic. This review discusses the intricate relationship between sleep, inflammation, and hemodynamics in pre-clinical rodent models of TBI.
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Affiliation(s)
- Tabitha R. F. Green
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO, United States
| | - Sean D. Carey
- Veterans Affairs (VA) Boston Healthcare System, West Roxbury, MA, United States
- Department of Psychiatry, Harvard Medical School, West Roxbury, MA, United States
| | - Grant Mannino
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO, United States
| | - John A. Craig
- Veterans Affairs (VA) Boston Healthcare System, West Roxbury, MA, United States
| | - Rachel K. Rowe
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO, United States
| | - Mark R. Zielinski
- Veterans Affairs (VA) Boston Healthcare System, West Roxbury, MA, United States
- Department of Psychiatry, Harvard Medical School, West Roxbury, MA, United States
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Ortiz JB, Tellez S, Rampal G, Mannino GS, Couillard N, Mendez M, Green TRF, Murphy SM, Rowe RK. Diffuse traumatic brain injury substantially alters plasma growth hormone in the juvenile rat. J Endocrinol 2024; 260:e230157. [PMID: 37855319 PMCID: PMC10692649 DOI: 10.1530/joe-23-0157] [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] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 10/18/2023] [Indexed: 10/20/2023]
Abstract
Traumatic brain injury (TBI) can damage the hypothalamus and cause improper activation of the growth hormone (GH) axis, leading to growth hormone deficiency (GHD). GHD is one of the most prevalent endocrinopathies following TBI in adults; however, the extent to which GHD affects juveniles remains understudied. We used postnatal day 17 rats (n = 83), which model the late infantile/toddler period, and assessed body weights, GH levels, and number of hypothalamic somatostatin neurons at acute (1, 7 days post injury (DPI)) and chronic (18, 25, 43 DPI) time points. We hypothesized that diffuse TBI would alter circulating GH levels because of damage to the hypothalamus, specifically somatostatin neurons. Data were analyzed with generalized linear and mixed effects models with fixed effects interactions between the injury and time. Despite similar growth rates over time with age, TBI rats weighed less than shams at 18 DPI (postnatal day 35; P = 0.03, standardized effect size [d] = 1.24), which is around the onset of puberty. Compared to shams, GH levels were lower in the TBI group during the acute period (P = 0.196; d = 12.3) but higher in the TBI group during the chronic period (P = 0.10; d = 52.1). Although not statistically significant, TBI-induced differences in GH had large standardized effect sizes, indicating biological significance. The mean number of hypothalamic somatostatin neurons (an inhibitor of GH) positively predicted GH levels in the hypothalamus but did not predict GH levels in the somatosensory cortex. Understanding TBI-induced alterations in the GH axis may identify therapeutic targets to improve the quality of life of pediatric survivors of TBI.
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Affiliation(s)
- J Bryce Ortiz
- Barrow Neurological Institute at Phoenix Children’s Hospital, Phoenix, Arizona, USA
- Department of Child Health, University of Arizona College of Medicine, Phoenix, Arizona, USA
| | - Sebastian Tellez
- Arizona State University, School of Life Sciences, Tempe, Arizona, USA
| | - Giri Rampal
- Department of Child Health, University of Arizona College of Medicine, Phoenix, Arizona, USA
- Department of Biology and Biochemistry, University of Bath, Bath, United Kingdom
| | - Grant S Mannino
- Department of Integrative Physiology, University of Colorado, Boulder, Colorado, USA
| | - Nicole Couillard
- Department of Integrative Physiology, University of Colorado, Boulder, Colorado, USA
| | - Matias Mendez
- Department of Integrative Physiology, University of Colorado, Boulder, Colorado, USA
| | - Tabitha R F Green
- Department of Integrative Physiology, University of Colorado, Boulder, Colorado, USA
| | - Sean M Murphy
- Department of Integrative Physiology, University of Colorado, Boulder, Colorado, USA
| | - Rachel K Rowe
- Department of Integrative Physiology, University of Colorado, Boulder, Colorado, USA
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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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Green TRF, Murphy SM, Rowe RK. Comparisons of quantitative approaches for assessing microglial morphology reveal inconsistencies, ecological fallacy, and a need for standardization. Sci Rep 2022; 12:18196. [PMID: 36307475 PMCID: PMC9616881 DOI: 10.1038/s41598-022-23091-2] [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] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Accepted: 10/25/2022] [Indexed: 12/31/2022] Open
Abstract
Microglial morphology is used to measure neuroinflammation and pathology. For reliable inference, it is critical that microglial morphology is accurately quantified and that results can be easily interpreted and compared across studies and laboratories. The process through which microglial morphology is quantified is a key methodological choice and little is known about how this choice may bias conclusions. We applied five of the most commonly used ImageJ-based methods for quantifying the microglial morphological response to a stimulus to identical photomicrographs and individual microglial cells isolated from these photomicrographs, which allowed for direct comparisons of results generated using these approaches. We found a lack of comparability across methods that analyzed full photomicrographs, with significant discrepancies in results among the five methods. Quantitative methods to analyze microglial morphology should be selected based on several criteria, and combinations of these methods may give the most biologically accurate representation of microglial morphology.
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Affiliation(s)
- Tabitha R. F. Green
- grid.134563.60000 0001 2168 186XDepartment of Child Health, University of Arizona College of Medicine-Phoenix, Phoenix, AZ USA ,grid.266190.a0000000096214564Department of Integrative Physiology, University of Colorado, 2860 Wilderness Place, Boulder, CO 80301 USA
| | - Sean M. Murphy
- grid.134563.60000 0001 2168 186XDepartment of Child Health, University of Arizona College of Medicine-Phoenix, Phoenix, AZ USA
| | - Rachel K. Rowe
- grid.134563.60000 0001 2168 186XDepartment of Child Health, University of Arizona College of Medicine-Phoenix, Phoenix, AZ USA ,grid.266190.a0000000096214564Department of Integrative Physiology, University of Colorado, 2860 Wilderness Place, Boulder, CO 80301 USA
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Green TRF, Murphy SM, Moreno-Montano MP, Audinat E, Rowe RK. Reactive morphology of dividing microglia following kainic acid administration. Front Neurosci 2022; 16:972138. [PMID: 36248637 PMCID: PMC9556904 DOI: 10.3389/fnins.2022.972138] [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] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Accepted: 09/02/2022] [Indexed: 11/13/2022] Open
Abstract
The microglial response to a pathological microenvironment is hallmarked by a change in cellular morphology. Following a pathological stimulus, microglia become reactive and simultaneously divide to create daughter cells. Although a wide array of microglial morphologies has been observed, the exact functions of these distinct morphologies are unknown, as are the morphology and reactivity status of dividing microglia. In this study, we used kainic acid to trigger microglial activation and cell division. Following a cortical kainic acid injection, microglial morphology and proliferation were examined at 3 days post-injection using immunohistochemistry for ionized calcium binding adapter molecule 1 (Iba1) to stain for microglia, and KI67 as a marker of cell division. Individual microglial cells were isolated from photomicrographs and skeletal and fractal analyses were used to examine cell size and spatial complexity. We examined the morphology of microglia in both wildtype and microglia-specific tumor necrosis factor (TNF)-α knockout mice. Data were analyzed using generalized linear mixed models or a two-way ANOVA. We found that dividing microglia had a more reactive morphology (larger cell body area, longer cell perimeter, and less ramification) compared to microglia that were not dividing, regardless of microglial release of TNF-α. However, we also observed dividing microglia with a complex, more ramified morphology. Changes in microglial morphology and division were greatest near the kainic acid injection site. This study uses robust and quantitative techniques to better understand microglial cell division, morphology, and population dynamics, which are essential for the development of novel therapeutics that target microglia.
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Affiliation(s)
- Tabitha R. F. Green
- Department of Child Health, University of Arizona College of Medicine - Phoenix, Phoenix, AZ, United States
| | - Sean M. Murphy
- Department of Child Health, University of Arizona College of Medicine - Phoenix, Phoenix, AZ, United States
| | - Maria P. Moreno-Montano
- Institute of Functional Genomics (IGF), University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Etienne Audinat
- Institute of Functional Genomics (IGF), University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Rachel K. Rowe
- Department of Child Health, University of Arizona College of Medicine - Phoenix, Phoenix, AZ, United States
- Department of Integrative Physiology, University of Colorado, Boulder, CO, United States
- *Correspondence: Rachel K. Rowe,
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Rowe RK, Green TRF, Giordano KR, Ortiz JB, Murphy SM, Opp MR. Microglia Are Necessary to Regulate Sleep after an Immune Challenge. Biology (Basel) 2022; 11:1241. [PMID: 36009868 PMCID: PMC9405260 DOI: 10.3390/biology11081241] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/04/2022] [Revised: 07/29/2022] [Accepted: 08/17/2022] [Indexed: 12/31/2022]
Abstract
Microglia play a critical role in the neuroimmune response, but little is known about the role of microglia in sleep following an inflammatory trigger. Nevertheless, decades of research have been predicated on the assumption that an inflammatory trigger increases sleep through microglial activation. We hypothesized that mice (n = 30) with depleted microglia using PLX5622 (PLX) would sleep less following the administration of lipopolysaccharide (LPS) to induce inflammation. Brains were collected and microglial morphology was assessed using quantitative skeletal analyses and physiological parameters were recorded using non-invasive piezoelectric cages. Mice fed PLX diet had a transient increase in sleep that dissipated by week 2. Subsequently, following a first LPS injection (0.4 mg/kg), mice with depleted microglia slept more than mice on the control diet. All mice were returned to normal rodent chow to repopulate microglia in the PLX group (10 days). Nominal differences in sleep existed during the microglia repopulation period. However, following a second LPS injection, mice with repopulated microglia slept similarly to control mice during the dark period but with longer bouts during the light period. Comparing sleep after the first LPS injection to sleep after the second LPS injection, controls exhibited temporal changes in sleep patterns but no change in cumulative minutes slept, whereas cumulative sleep in mice with repopulated microglia decreased during the dark period across all days. Repopulated microglia had a reactive morphology. We conclude that microglia are necessary to regulate sleep after an immune challenge.
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Affiliation(s)
- Rachel K. Rowe
- Department of Integrative Physiology, University of Colorado, Boulder, CO 80301, USA
- Barrow Neurological Institute at Phoenix Children’s Hospital, Phoenix, AZ 85016, USA
- Department of Child Health, University of Arizona College of Medicine-Phoenix, Phoenix, AZ 85004, USA
| | - Tabitha R. F. Green
- Department of Child Health, University of Arizona College of Medicine-Phoenix, Phoenix, AZ 85004, USA
| | - Katherine R. Giordano
- Department of Child Health, University of Arizona College of Medicine-Phoenix, Phoenix, AZ 85004, USA
- Phoenix Veterans Affairs Health Care System, Phoenix, AZ 85012, USA
| | - J. Bryce Ortiz
- Department of Child Health, University of Arizona College of Medicine-Phoenix, Phoenix, AZ 85004, USA
- Phoenix Veterans Affairs Health Care System, Phoenix, AZ 85012, USA
| | - Sean M. Murphy
- Department of Child Health, University of Arizona College of Medicine-Phoenix, Phoenix, AZ 85004, USA
| | - Mark R. Opp
- Department of Integrative Physiology, University of Colorado, Boulder, CO 80301, USA
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Green TRF, Murphy SM, Ortiz JB, Rowe RK. Age-At-Injury Influences the Glial Response to Traumatic Brain Injury in the Cortex of Male Juvenile Rats. Front Neurol 2022; 12:804139. [PMID: 35111130 PMCID: PMC8802670 DOI: 10.3389/fneur.2021.804139] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Accepted: 12/14/2021] [Indexed: 11/29/2022] Open
Abstract
Few translational studies have examined how age-at-injury affects the glial response to traumatic brain injury (TBI). We hypothesized that rats injured at post-natal day (PND) 17 would exhibit a greater glial response, that would persist into early adulthood, compared to rats injured at PND35. PND17 and PND35 rats (n = 75) received a mild to moderate midline fluid percussion injury or sham surgery. In three cortical regions [peri-injury, primary somatosensory barrel field (S1BF), perirhinal], we investigated the glial response relative to age-at-injury (PND17 or PND35), time post-injury (2 hours, 1 day, 7 days, 25 days, or 43 days), and post-natal age, such that rats injured at PND17 or PND35 were compared at the same post-natal-age (e.g., PND17 + 25D post-injury = PND42; PND35 + 7D post-injury = PND42). We measured Iba1 positive microglia cells (area, perimeter) and quantified their activation status using skeletal analysis (branch length/cell, mean processes/cell, cell abundance). GFAP expression was examined using immunohistochemistry and pixel analysis. Data were analyzed using Bayesian multivariate multi-level models. Independent of age-at-injury, TBI activated microglia (shorter branches, fewer processes) in the S1BF and perirhinal cortex with more microglia in all regions compared to uninjured shams. TBI-induced microglial activation (shorter branches) was sustained in the S1BF into early adulthood (PND60). Overall, PND17 injured rats had more microglial activation in the perirhinal cortex than PND35 injured rats. Activation was not confounded by age-dependent cell size changes, and microglial cell body sizes were similar between PND17 and PND35 rats. There were no differences in astrocyte GFAP expression. Increased microglial activation in PND17 brain-injured rats suggests that TBI upregulates the glial response at discrete stages of development. Age-at-injury and aging with an injury are translationally important because experiencing a TBI at an early age may trigger an exaggerated glial response.
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Affiliation(s)
- Tabitha R. F. Green
- Department of Child Health, University of Arizona College of Medicine-Phoenix, Phoenix, AZ, United States
| | - Sean M. Murphy
- Department of Child Health, University of Arizona College of Medicine-Phoenix, Phoenix, AZ, United States
| | - J. Bryce Ortiz
- Department of Child Health, University of Arizona College of Medicine-Phoenix, Phoenix, AZ, United States
- Phoenix Veterans Affairs (VA) Health Care System, Phoenix, AZ, United States
| | - Rachel K. Rowe
- Department of Child Health, University of Arizona College of Medicine-Phoenix, Phoenix, AZ, United States
- Department of Integrative Physiology, University of Colorado, Boulder, CO, United States
- BARROW Neurological Institute at Phoenix Children's Hospital, Phoenix, AZ, United States
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Apostol CR, Bernard K, Tanguturi P, Molnar G, Bartlett MJ, Szabò L, Liu C, Ortiz JB, Saber M, Giordano KR, Green TRF, Melvin J, Morrison HW, Madhavan L, Rowe RK, Streicher JM, Heien ML, Falk T, Polt R. Design and Synthesis of Brain Penetrant Glycopeptide Analogues of PACAP With Neuroprotective Potential for Traumatic Brain Injury and Parkinsonism. Front Drug Discov (Lausanne) 2022; 1. [PMID: 35237767 PMCID: PMC8887546 DOI: 10.3389/fddsv.2021.818003] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
There is an unmet clinical need for curative therapies to treat neurodegenerative disorders. Most mainstay treatments currently on the market only alleviate specific symptoms and do not reverse disease progression. The Pituitary adenylate cyclase-activating polypeptide (PACAP), an endogenous neuropeptide hormone, has been extensively studied as a potential regenerative therapeutic. PACAP is widely distributed in the central nervous system (CNS) and exerts its neuroprotective and neurotrophic effects via the related Class B GPCRs PAC1, VPAC1, and VPAC2, at which the hormone shows roughly equal activity. Vasoactive intestinal peptide (VIP) also activates these receptors, and this close analogue of PACAP has also shown to promote neuronal survival in various animal models of acute and progressive neurodegenerative diseases. However, PACAP's poor pharmacokinetic profile (non-linear PK/PD), and more importantly its limited blood-brain barrier (BBB) permeability has hampered development of this peptide as a therapeutic. We have demonstrated that glycosylation of PACAP and related peptides promotes penetration of the BBB and improves PK properties while retaining efficacy and potency in the low nanomolar range at its target receptors. Furthermore, judicious structure-activity relationship (SAR) studies revealed key motifs that can be modulated to afford compounds with diverse selectivity profiles. Most importantly, we have demonstrated that select PACAP glycopeptide analogues (2LS80Mel and 2LS98Lac) exert potent neuroprotective effects and anti-inflammatory activity in animal models of traumatic brain injury and in a mild-toxin lesion model of Parkinson's disease, highlighting glycosylation as a viable strategy for converting endogenous peptides into robust and efficacious drug candidates.
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Affiliation(s)
- Christopher R Apostol
- Department of Chemistry and Biochemistry, BIO5, The University of Arizona, Tucson, AZ, United States
| | - Kelsey Bernard
- Graduate Interdisciplinary Program in Physiological Sciences, The University of Arizona, Tucson, AZ, United States
| | | | - Gabriella Molnar
- Department of Pharmacology, College of Medicine, The University of Arizona, Tucson, AZ, United States
| | - Mitchell J Bartlett
- Department of Neurology, College of Medicine, The University of Arizona, Tucson, AZ, United States
| | - Lajos Szabò
- Department of Chemistry and Biochemistry, BIO5, The University of Arizona, Tucson, AZ, United States
| | - Chenxi Liu
- Department of Chemistry and Biochemistry, BIO5, The University of Arizona, Tucson, AZ, United States
| | - J Bryce Ortiz
- Barrow Neurological Institute at Phoenix Children's Hospital, The University of Arizona College of Medicine-Phoenix, Phoenix, AZ, United States.,Department of Child Health, The University of Arizona College of Medicine-Phoenix, Phoenix, AZ, United States.,Phoenix Veteran Affairs Health Care System, Phoenix, AZ, United States
| | - Maha Saber
- Barrow Neurological Institute at Phoenix Children's Hospital, The University of Arizona College of Medicine-Phoenix, Phoenix, AZ, United States.,Department of Child Health, The University of Arizona College of Medicine-Phoenix, Phoenix, AZ, United States
| | - Katherine R Giordano
- Barrow Neurological Institute at Phoenix Children's Hospital, The University of Arizona College of Medicine-Phoenix, Phoenix, AZ, United States.,Department of Child Health, The University of Arizona College of Medicine-Phoenix, Phoenix, AZ, United States.,Phoenix Veteran Affairs Health Care System, Phoenix, AZ, United States
| | - Tabitha R F Green
- Department of Child Health, The University of Arizona College of Medicine-Phoenix, Phoenix, AZ, United States
| | - James Melvin
- Department of Child Health, The University of Arizona College of Medicine-Phoenix, Phoenix, AZ, United States.,Department of Biological Sciences, University of Bath, Bath, United Kingdom
| | - Helena W Morrison
- College of Nursing, University of Arizona, Tucson, AZ, United States
| | - Lalitha Madhavan
- Graduate Interdisciplinary Program in Physiological Sciences, The University of Arizona, Tucson, AZ, United States.,Department of Neurology, College of Medicine, The University of Arizona, Tucson, AZ, United States
| | - Rachel K Rowe
- Barrow Neurological Institute at Phoenix Children's Hospital, The University of Arizona College of Medicine-Phoenix, Phoenix, AZ, United States.,Department of Child Health, The University of Arizona College of Medicine-Phoenix, Phoenix, AZ, United States.,Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO, United States
| | - John M Streicher
- Department of Pharmacology, College of Medicine, The University of Arizona, Tucson, AZ, United States
| | - Michael L Heien
- Department of Chemistry and Biochemistry, BIO5, The University of Arizona, Tucson, AZ, United States
| | - Torsten Falk
- Graduate Interdisciplinary Program in Physiological Sciences, The University of Arizona, Tucson, AZ, United States.,Department of Pharmacology, College of Medicine, The University of Arizona, Tucson, AZ, United States.,Department of Neurology, College of Medicine, The University of Arizona, Tucson, AZ, United States
| | - Robin Polt
- Department of Chemistry and Biochemistry, BIO5, The University of Arizona, Tucson, AZ, United States
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10
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Green TRF, Ortiz JB, Wonnacott S, Williams RJ, Rowe RK. The Bidirectional Relationship Between Sleep and Inflammation Links Traumatic Brain Injury and Alzheimer's Disease. Front Neurosci 2020; 14:894. [PMID: 32982677 PMCID: PMC7479838 DOI: 10.3389/fnins.2020.00894] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [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: 04/06/2020] [Accepted: 07/31/2020] [Indexed: 12/18/2022] Open
Abstract
Traumatic brain injury (TBI) and Alzheimer's disease (AD) are diseases during which the fine-tuned autoregulation of the brain is lost. Despite the stark contrast in their causal mechanisms, both TBI and AD are conditions which elicit a neuroinflammatory response that is coupled with physical, cognitive, and affective symptoms. One commonly reported symptom in both TBI and AD patients is disturbed sleep. Sleep is regulated by circadian and homeostatic processes such that pathological inflammation may disrupt the chemical signaling required to maintain a healthy sleep profile. In this way, immune system activation can influence sleep physiology. Conversely, sleep disturbances can exacerbate symptoms or increase the risk of inflammatory/neurodegenerative diseases. Both TBI and AD are worsened by a chronic pro-inflammatory microenvironment which exacerbates symptoms and worsens clinical outcome. Herein, a positive feedback loop of chronic inflammation and sleep disturbances is initiated. In this review, the bidirectional relationship between sleep disturbances and inflammation is discussed, where chronic inflammation associated with TBI and AD can lead to sleep disturbances and exacerbated neuropathology. The role of microglia and cytokines in sleep disturbances associated with these diseases is highlighted. The proposed sleep and inflammation-mediated link between TBI and AD presents an opportunity for a multifaceted approach to clinical intervention.
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Affiliation(s)
- Tabitha R. F. Green
- BARROW Neurological Institute at Phoenix Children’s Hospital, Phoenix, AZ, United States
- Department of Child Health, University of Arizona College of Medicine – Phoenix, Phoenix, AZ, United States
| | - J. Bryce Ortiz
- BARROW Neurological Institute at Phoenix Children’s Hospital, Phoenix, AZ, United States
- Department of Child Health, University of Arizona College of Medicine – Phoenix, Phoenix, AZ, United States
| | - Sue Wonnacott
- Department of Biology and Biochemistry, University of Bath, Bath, United Kingdom
| | - Robert J. Williams
- Department of Biology and Biochemistry, University of Bath, Bath, United Kingdom
| | - Rachel K. Rowe
- BARROW Neurological Institute at Phoenix Children’s Hospital, Phoenix, AZ, United States
- Department of Child Health, University of Arizona College of Medicine – Phoenix, Phoenix, AZ, United States
- Phoenix Veteran Affairs Health Care System, Phoenix, AZ, United States
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Abstract
Histology and immunohistochemistry are routine methods of analysis to visualize microscopic anatomy and localize proteins within biological tissue. In neuroscience, as well as a plethora of other scientific fields, these techniques are used. Immunohistochemistry can be done on slide mounted tissue or free-floating sections. Preparing slide-mounted samples is a time intensive process. The following protocol for a technique, called the Megabrain, reduced the time taken to cryosection and mount brain tissue by up to 90% by combining multiple brains into a single frozen block. Furthermore, this technique reduced variability seen between staining rounds, in a large histochemical study. The current technique has been optimized for using rodent brain tissue in downstream immunohistochemical analyses; however, it can be applied to different scientific fields that use cryosectioning.
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Affiliation(s)
- Tabitha R F Green
- Department of Child Health, University of Arizona College of Medicine; Department of Biological Sciences, University of Bath; BARROW Neurological Institute at Phoenix Children's Hospital
| | - J Bryce Ortiz
- Department of Child Health, University of Arizona College of Medicine
| | - Jordan L Harrison
- Department of Basic Medical Sciences, University of Arizona College of Medicine
| | - Jonathan Lifshitz
- Department of Child Health, University of Arizona College of Medicine; BARROW Neurological Institute at Phoenix Children's Hospital; Phoenix Veteran Affairs Healthcare System
| | - Rachel K Rowe
- Department of Child Health, University of Arizona College of Medicine; BARROW Neurological Institute at Phoenix Children's Hospital; Phoenix Veteran Affairs Healthcare System;
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