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Anderberg RH, Andersson EA, Bucher V, Preissner KT, Mallard C, Ek CJ. Treatment with RNase alleviates brain injury but not neuroinflammation in neonatal hypoxia/ischemia. J Neurosci Res 2024; 102:e25329. [PMID: 38597144 DOI: 10.1002/jnr.25329] [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: 05/04/2023] [Revised: 03/14/2024] [Accepted: 03/30/2024] [Indexed: 04/11/2024]
Abstract
There is a need for new treatments to reduce brain injuries derived from neonatal hypoxia/ischemia. The only viable option used in the clinic today in infants born at term is therapeutic hypothermia, which has a limited efficacy. Treatments with exogenous RNase have shown great promise in a range of different adult animal models including stroke, ischemia/reperfusion injury, or experimental heart transplantation, often by conferring vascular protective and anti-inflammatory effects. However, any neuroprotective function of RNase treatment in the neonate remains unknown. Using a well-established model of neonatal hypoxic/ischemic brain injury, we evaluated the influence of RNase treatment on RNase activity, gray and white matter tissue loss, blood-brain barrier function, as well as levels and expression of inflammatory cytokines in the brain up to 6 h after the injury using multiplex immunoassay and RT-PCR. Intraperitoneal treatment with RNase increased RNase activity in both plasma and cerebropinal fluids. The RNase treatment resulted in a reduction of brain tissue loss but did not affect the blood-brain barrier function and had only a minor modulatory effect on the inflammatory response. It is concluded that RNase treatment may be promising as a neuroprotective regimen, whereas the mechanistic effects of this treatment appear to be different in the neonate compared to the adult and need further investigation.
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Affiliation(s)
- Rozita H Anderberg
- Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - E Axel Andersson
- Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Valentina Bucher
- Department of Obstetrics and Gynecology, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Klaus T Preissner
- Department of Cardiology, Medical School, Kerckhoff-Heart Research Institute, Justus-Liebig-University, Giessen, Germany
| | - Carina Mallard
- Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - C Joakim Ek
- Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
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Chumak T, Jullienne A, Joakim Ek C, Ardalan M, Svedin P, Quan R, Salehi A, Salari S, Obenaus A, Vexler ZS, Mallard C. Maternal n-3 enriched diet reprograms neurovascular transcriptome and blunts inflammation in neonate. bioRxiv 2024:2024.01.22.576634. [PMID: 38328227 PMCID: PMC10849562 DOI: 10.1101/2024.01.22.576634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2024]
Abstract
Infection during perinatal period can adversely affect brain development, predispose infants to ischemic stroke and have lifelong consequences. We previously demonstrated that diet enriched in n-3 polyunsaturated fatty acids (PUFA) transforms brain lipid composition and protects from neonatal stroke. Vasculature is a critical interface between blood and brain providing a barrier to systemic infection. Here we examined whether maternal PUFA-enriched diets exert reprograming of endothelial cell signalling in 9-day old mice after endotoxin (LPS)-induced infection. Transcriptome analysis was performed on brain microvessels from pups born to dams maintained on 3 diets: standard, n-3 or n-6 enriched. N-3 diet enabled higher immune reactivity in brain vasculature, while preventing imbalance of cell cycle regulation and extracellular matrix cascades that accompanied inflammatory response in standard diet. LPS response in blood and brain was blunted in n-3 offspring. Cerebral angioarchitecture analysis revealed modified vessel complexity after LPS. Thus, n-3-enriched maternal diet partially prevents imbalance in homeostatic processes and alters inflammation rather than affects brain vascularization during early life. Importantly, maternal diet may presage offspring neurovascular outcomes later in life.
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Nilsson G, Mottahedin A, Zelco A, Lauschke VM, Ek CJ, Song J, Ardalan M, Hua S, Zhang X, Mallard C, Hagberg H, Leavenworth JW, Wang X. Two different isoforms of osteopontin modulate myelination and axonal integrity. FASEB Bioadv 2023; 5:336-353. [PMID: 37554545 PMCID: PMC10405251 DOI: 10.1096/fba.2023-00030] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2023] [Revised: 05/22/2023] [Accepted: 06/06/2023] [Indexed: 08/10/2023] Open
Abstract
Abnormal myelination underlies the pathology of white matter diseases such as preterm white matter injury and multiple sclerosis. Osteopontin (OPN) has been suggested to play a role in myelination. Murine OPN mRNA is translated into a secreted isoform (sOPN) or an intracellular isoform (iOPN). Whether there is an isoform-specific involvement of OPN in myelination is unknown. Here we generated mouse models that either lacked both OPN isoforms in all cells (OPN-KO) or lacked sOPN systemically but expressed iOPN specifically in oligodendrocytes (OLs-iOPN-KI). Transcriptome analysis of isolated oligodendrocytes from the neonatal brain showed that genes and pathways related to increase of myelination and altered cell cycle control were enriched in the absence of the two OPN isoforms in OPN-KO mice compared to control mice. Accordingly, adult OPN-KO mice showed an increased axonal myelination, as revealed by transmission electron microscopy imaging, and increased expression of myelin-related proteins. In contrast, neonatal oligodendrocytes from OLs-iOPN-KI mice compared to control mice showed differential regulation of genes and pathways related to the increase of cell adhesion, motility, and vasculature development, and the decrease of axonal/neuronal development. OLs-iOPN-KI mice showed abnormal myelin formation in the early phase of myelination in young mice and signs of axonal degeneration in adulthood. These results suggest an OPN isoform-specific involvement, and a possible interplay between the isoforms, in myelination, and axonal integrity. Thus, the two isoforms of OPN need to be separately considered in therapeutic strategies targeting OPN in white matter injury and diseases.
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Affiliation(s)
- Gisela Nilsson
- Centre of Perinatal Medicine & Health, Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska AcademyUniversity of GothenburgGothenburgSweden
| | - Amin Mottahedin
- Centre of Perinatal Medicine & Health, Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska AcademyUniversity of GothenburgGothenburgSweden
| | - Aura Zelco
- Centre of Perinatal Medicine & Health, Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska AcademyUniversity of GothenburgGothenburgSweden
| | - Volker M. Lauschke
- Department of Physiology and PharmacologyKarolinska InstituteStockholmSweden
- Dr Margarete Fischer‐Bosch Institute of Clinical PharmacologyStuttgartGermany
- University of TübingenTübingenGermany
| | - C. Joakim Ek
- Centre of Perinatal Medicine & Health, Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska AcademyUniversity of GothenburgGothenburgSweden
| | - Juan Song
- Centre of Perinatal Medicine & Health, Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska AcademyUniversity of GothenburgGothenburgSweden
- Henan Key Laboratory of Child Brain InjuryInstitute of Neuroscience and Third Affiliated Hospital of Zhengzhou UniversityZhengzhouChina
| | - Maryam Ardalan
- Centre of Perinatal Medicine & Health, Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska AcademyUniversity of GothenburgGothenburgSweden
| | - Sha Hua
- Centre of Perinatal Medicine & Health, Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska AcademyUniversity of GothenburgGothenburgSweden
- Department of Cardiology, Ruijin Hospital/Luwan Branch, School of MedicineShanghai Jiao Tong UniversityShanghaiChina
| | - Xiaoli Zhang
- Centre of Perinatal Medicine & Health, Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska AcademyUniversity of GothenburgGothenburgSweden
- Henan Key Laboratory of Child Brain InjuryInstitute of Neuroscience and Third Affiliated Hospital of Zhengzhou UniversityZhengzhouChina
| | - Carina Mallard
- Centre of Perinatal Medicine & Health, Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska AcademyUniversity of GothenburgGothenburgSweden
| | - Henrik Hagberg
- Centre of Perinatal Medicine & Health, Department of Obstetrics and Gynaecology, Institute of Clinical Sciences, Sahlgrenska AcademyUniversity of GothenburgGothenburgSweden
| | - Jianmei W. Leavenworth
- Department of NeurosurgeryUniversity of Alabama at BirminghamBirminghamAlabamaUSA
- Department of MicrobiologyUniversity of Alabama at BirminghamBirminghamAlabamaUSA
| | - Xiaoyang Wang
- Centre of Perinatal Medicine & Health, Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska AcademyUniversity of GothenburgGothenburgSweden
- Henan Key Laboratory of Child Brain InjuryInstitute of Neuroscience and Third Affiliated Hospital of Zhengzhou UniversityZhengzhouChina
- Centre of Perinatal Medicine & Health, Department of Obstetrics and Gynaecology, Institute of Clinical Sciences, Sahlgrenska AcademyUniversity of GothenburgGothenburgSweden
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Rayasam A, Jullienne A, Chumak T, Faustino J, Szu J, Hamer M, Ek CJ, Mallard C, Obenaus A, Vexler ZS. Viral mimetic triggers cerebral arteriopathy in juvenile brain via neutrophil elastase and NETosis. J Cereb Blood Flow Metab 2021; 41:3171-3186. [PMID: 34293939 PMCID: PMC8669290 DOI: 10.1177/0271678x211032737] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Stroke is among the top ten causes of death in children but has received disproportionally little attention. Cerebral arteriopathies account for up to 80% of childhood arterial ischemic stroke (CAIS) cases and are strongly predictive of CAIS recurrence and poorer outcomes. The underlying mechanisms of sensitization of neurovasculature by viral infection are undefined. In the first age-appropriate model for childhood arteriopathy-by administration of viral mimetic TLR3-agonist Polyinosinic:polycytidylic acid (Poly-IC) in juvenile mice-we identified a key role of the TLR3-neutrophil axis in disrupting the structural-functional integrity of the blood-brain barrier (BBB) and distorting the developing neurovascular architecture and vascular networks. First, using an array of in-vivo/post-vivo vascular imaging, genetic, enzymatic and pharmacological approaches, we report marked Poly-IC-mediated extravascular leakage of albumin (66kDa) and of a small molecule DiI (∼934Da) and disrupted tight junctions. Poly-IC also enhanced the neuroinflammatory milieu, promoted neutrophil recruitment, profoundly upregulated neutrophil elastase (NE), and induced neutrophil extracellular trap formation (NETosis). Finally, we show that functional BBB disturbances, NETosis and neuroinflammation are markedly attenuated by pharmacological inhibition of NE (Sivelestat). Altogether, these data reveal NE/NETosis as a novel therapeutic target for viral-induced cerebral arteriopathies in children.
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Affiliation(s)
- Aditya Rayasam
- Department of Neurology, University California San Francisco, San Francisco, CA, USA
| | - Amandine Jullienne
- Department of Pediatrics, University of California Irvine, Irvine, CA, USA
| | - Tetyana Chumak
- Department of Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Joel Faustino
- Department of Neurology, University California San Francisco, San Francisco, CA, USA
| | - Jenny Szu
- Department of Pediatrics, University of California Irvine, Irvine, CA, USA
| | - Mary Hamer
- Department of Pediatrics, University of California Irvine, Irvine, CA, USA
| | - C Joakim Ek
- Department of Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Carina Mallard
- Department of Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Andre Obenaus
- Department of Pediatrics, University of California Irvine, Irvine, CA, USA
| | - Zinaida S Vexler
- Department of Neurology, University California San Francisco, San Francisco, CA, USA
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Andersson EA, Mallard C, Ek CJ. Circulating tight-junction proteins are potential biomarkers for blood-brain barrier function in a model of neonatal hypoxic/ischemic brain injury. Fluids Barriers CNS 2021; 18:7. [PMID: 33568200 PMCID: PMC7877092 DOI: 10.1186/s12987-021-00240-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [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: 01/18/2021] [Indexed: 12/13/2022] Open
Abstract
Background Neonatal encephalopathy often leads to lifelong disabilities with limited treatments currently available. The brain vasculature is an important factor in many neonatal neurological disorders but there is a lack of diagnostic tools to evaluate the brain vascular dysfunction of neonates in the clinical setting. Measurement of blood–brain barrier tight-junction (TJ) proteins have shown promise as biomarkers for brain injury in the adult. Here we tested the biomarker potential of tight-junctions in the context of neonatal brain injury. Methods The levels of TJ-proteins (occluding, claudin-5, and zonula occludens protein 1) in both blood plasma and cerebrospinal fluid (CSF) as well as blood–brain barrier function via 14C-sucrose (342 Da) and Evans blue extravasation were measured in a hypoxia/ischemia brain-injury model in neonatal rats. Results Time-dependent changes of occludin and claudin-5 levels could be measured in blood and CSF after hypoxia/ischemia with males generally having higher levels than females. The levels of claudin-5 in CSF correlated with the severity of the brain injury at 24 h post- hypoxia/ischemia. Simultaneously, we detected early increase in blood–brain barrier-permeability at 6 and 24 h after hypoxia/ischemia. Conclusions Levels of circulating claudin-5 and occludin are increased after hypoxic/ischemic brain injuries and blood–brain barrier-impairment and have promise as early biomarkers for cerebral vascular dysfunction and as a tool for risk assessment of neonatal brain injuries.
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Affiliation(s)
- E Axel Andersson
- Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Medicinaregatan 11, 413 90, Gothenburg, Sweden
| | - Carina Mallard
- Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Medicinaregatan 11, 413 90, Gothenburg, Sweden
| | - C Joakim Ek
- Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Medicinaregatan 11, 413 90, Gothenburg, Sweden.
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Gravina G, Svedin P, Ardalan M, Levy O, Ek CJ, Mallard C, Lai JCY. Staphylococcus epidermidis Sensitizes Perinatal Hypoxic-Ischemic Brain Injury in Male but Not Female Mice. Front Immunol 2020; 11:516. [PMID: 32373108 PMCID: PMC7186320 DOI: 10.3389/fimmu.2020.00516] [Citation(s) in RCA: 8] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 03/06/2020] [Indexed: 12/21/2022] Open
Abstract
Background: Staphylococcus epidermidis is the most common nosocomial infection and the predominant pathogen in late-onset sepsis in preterm infants. Infection and inflammation are linked to neurological and developmental sequelae and bacterial infections increase the vulnerability of the brain to hypoxia-ischemia (HI). We thus tested the hypothesis that S. epidermidis exacerbates HI neuropathology in neonatal mice. Methods: Male and female C57Bl/6 mice were injected intraperitoneally with sterile saline or 3.5 × 107 colony-forming units of S. epidermidis on postnatal day (PND) 4 and then subjected to HI on PND5 (24 h after injection) or PND9 (5 d after injection) by left carotid artery ligation and exposure to 10% O2. White and gray matter injury was assessed on PND14-16. In an additional group of animals, the plasma, brain, and liver were collected on PND5 or PND9 after infection to evaluate cytokine and chemokine profiles, C5a levels and C5 signaling. Results: HI induced 24 h after injection of S. epidermidis resulted in greater gray and white matter injury compared to saline injected controls in males, but not in females. Specifically, males demonstrated increased gray matter injury in the cortex and striatum, and white matter loss in the subcortical region, hippocampal fimbria and striatum. In contrast, there was no potentiation of brain injury when HI occurred 5 d after infection in either sex. In the plasma, S. epidermidis-injected mice demonstrated increased levels of pro- and anti-inflammatory cytokines and chemokines and a reduction of C5a at 24 h, but not 5 d after infection. Brain CCL2 levels were increased in both sexes 24 h after infection, but increased only in males at 5 d post infection. Conclusion: Ongoing S. epidermidis infection combined with neonatal HI increases the vulnerability of the developing brain in male but not in female mice. These sex-dependent effects were to a large extent independent of expression of systemic cytokines or brain CCL2 expression. Overall, we provide new insights into how systemic S. epidermidis infection affects the developing brain and show that the time interval between infection and HI is a critical sensitizing factor in males.
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Affiliation(s)
- Giacomo Gravina
- Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Pernilla Svedin
- Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Maryam Ardalan
- Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Ofer Levy
- Precision Vaccines Program, Boston Children's Hospital, Boston, MA, United States.,Department of Pediatrics, Harvard Medical School, Boston, MA, United States.,Broad Institute of MIT and Harvard, Cambridge, MA, United States
| | - C Joakim Ek
- Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Carina Mallard
- Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Jacqueline C Y Lai
- Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
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Lai JCY, Svedin P, Ek CJ, Mottahedin A, Wang X, Levy O, Currie A, Strunk T, Mallard C. Vancomycin Is Protective in a Neonatal Mouse Model of Staphylococcus epidermidis-Potentiated Hypoxic-Ischemic Brain Injury. Antimicrob Agents Chemother 2020; 64:e02003-19. [PMID: 31818825 PMCID: PMC7038267 DOI: 10.1128/aac.02003-19] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [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: 10/04/2019] [Accepted: 12/06/2019] [Indexed: 12/27/2022] Open
Abstract
Infection is correlated with increased risk of neurodevelopmental sequelae in preterm infants. In modeling neonatal brain injury, Toll-like receptor agonists have often been used to mimic infections and induce inflammation. Using the most common cause of bacteremia in preterm infants, Staphylococcus epidermidis, we present a more clinically relevant neonatal mouse model that addresses the combined effects of bacterial infection together with subsequent hypoxic-ischemic brain insult. Currently, there is no neuroprotective treatment for the preterm population. Hence, we tested the neuroprotective effects of vancomycin with and without adjunct therapy using the anti-inflammatory agent pentoxifylline. We characterized the effects of S. epidermidis infection on the inflammatory response in the periphery and the brain, as well as the physiological changes in the central nervous system that might affect neurodevelopmental outcomes. Intraperitoneal injection of postnatal day 4 mice with a live clinical isolate of S. epidermidis led to bacteremia and induction of proinflammatory cytokines in the blood, as well as transient elevations of neutrophil and monocyte chemotactic cytokines and caspase 3 activity in the brain. When hypoxia-ischemia was induced postinfection, more severe brain damage was observed in infected animals than in saline-injected controls. This infection-induced inflammation and potentiated brain injury was inoculum dose dependent and was alleviated by the antibiotic vancomycin. Pentoxifylline did not provide any additional neuroprotective effect. Thus, we show for the first time that live S. epidermidis potentiates hypoxic-ischemic preterm brain injury and that peripheral inhibition of inflammation with antibiotics, such as vancomycin, reduces the extent of brain injury.
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Affiliation(s)
- Jacqueline C Y Lai
- Center for Perinatal Medicine and Health, Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
- Precision Vaccines Program, Division of Infectious Diseases, Boston Children's Hospital, Boston, Massachusetts, USA
- Harvard Medical School, Harvard University, Boston, Massachusetts, USA
| | - Pernilla Svedin
- Center for Perinatal Medicine and Health, Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - C Joakim Ek
- Center for Perinatal Medicine and Health, Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Amin Mottahedin
- Center for Perinatal Medicine and Health, Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Xiaoyang Wang
- Center for Perinatal Medicine and Health, Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
- Henan Key Laboratory of Child Brain Injury, Third Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Ofer Levy
- Precision Vaccines Program, Division of Infectious Diseases, Boston Children's Hospital, Boston, Massachusetts, USA
- Harvard Medical School, Harvard University, Boston, Massachusetts, USA
- Broad Institute of Harvard and MIT, Cambridge, Massachusetts, USA
| | - Andrew Currie
- Centre for Neonatal Research and Education, University of Western Australia, Perth, Western Australia, Australia
- Medical, Molecular and Forensic Sciences, Murdoch University, Perth, Western Australia, Australia
| | - Tobias Strunk
- Centre for Neonatal Research and Education, University of Western Australia, Perth, Western Australia, Australia
- Neonatal Directorate, King Edward Memorial Hospital for Women, Subiaco, Western Australia, Australia
| | - Carina Mallard
- Center for Perinatal Medicine and Health, Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
- Henan Key Laboratory of Child Brain Injury, Third Affiliated Hospital of Zhengzhou University, Zhengzhou, China
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Abstract
Central nervous system homeostasis is maintained by cellular barriers that protect the brain from external environmental changes and protect the CNS from harmful molecules and pathogens in the blood. Historically, for many years these barriers were thought of as immature, with limited functions, during brain development. In this review, we will present advances in the understanding of the barrier systems during development and evidence to show that in fact the barriers serve many important neurodevelopmental functions and that fetal and newborn brains are well protected. We will also discuss how ischaemic injury or systemic inflammation may breach the integrity of the barriers in the developing brain.
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Affiliation(s)
- Carina Mallard
- Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Sweden
| | - C Joakim Ek
- Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Sweden
| | - Zinaida S Vexler
- Department of Neurology, University California San Francisco, USA
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Lai JCY, Rocha-Ferreira E, Ek CJ, Wang X, Hagberg H, Mallard C. Immune responses in perinatal brain injury. Brain Behav Immun 2017; 63:210-223. [PMID: 27865947 DOI: 10.1016/j.bbi.2016.10.022] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Revised: 10/28/2016] [Accepted: 10/30/2016] [Indexed: 12/13/2022] Open
Abstract
The perinatal period has often been described as immune deficient. However, it has become clear that immune responses in the neonate following exposure to microbes or as a result of tissue injury may be substantial and play a role in perinatal brain injury. In this article we will review the immune cell composition under normal physiological conditions in the perinatal period, both in the human and rodent. We will summarize evidence of the inflammatory responses to stimuli and discuss how neonatal immune activation, both in the central nervous system and in the periphery, may contribute to perinatal hypoxic-ischemic brain injury.
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Affiliation(s)
- Jacqueline C Y Lai
- Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Box 432, 405 30 Gothenburg, Sweden
| | - Eridan Rocha-Ferreira
- Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Box 432, 405 30 Gothenburg, Sweden
| | - C Joakim Ek
- Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Box 432, 405 30 Gothenburg, Sweden
| | - Xiaoyang Wang
- Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Box 432, 405 30 Gothenburg, Sweden
| | - Henrik Hagberg
- Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Box 432, 405 30 Gothenburg, Sweden
| | - Carina Mallard
- Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Box 432, 405 30 Gothenburg, Sweden.
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Kalm M, Boström M, Sandelius Å, Eriksson Y, Ek CJ, Blennow K, Björk-Eriksson T, Zetterberg H. Serum concentrations of the axonal injury marker neurofilament light protein are not influenced by blood-brain barrier permeability. Brain Res 2017; 1668:12-19. [PMID: 28522263 DOI: 10.1016/j.brainres.2017.05.011] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [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: 01/31/2017] [Revised: 03/31/2017] [Accepted: 05/10/2017] [Indexed: 11/16/2022]
Abstract
A blood biomarker to monitor individual susceptibility to neuronal injury from cranial radiotherapy could potentially help to individualize radiation treatment and thereby reduce the incidence and severity of late effects. An important feature of such a blood biomarker is that its concentration is not confounded by varying degrees of release from the brain into the blood across the blood-brain barrier (BBB). In this study, we investigated serum neurofilament light protein (NFL) concentrations in 21-day old mice following a single dose of cranial irradiation (8Gy). Cranial irradiation resulted in acute cell injury measured as a 12.9-fold increase in caspase activity 6h after irradiation; activation of inflammation measured by levels of CCL2 and increased BBB permeability measured by 14C-sucrose concentration ratios in brain and cerebrospinal fluid (CSF). Serum levels of NFL peaked at 6h after both anesthesia and cranial irradiation, but no timely correlation of serum NFL concentration with BBB permeability was found. Further, three groups of patients with different degrees of BBB impairment (measured as the CSF/serum albumin ratio) were investigated. There was no correlation between serum NFL concentration and CSF/serum albumin ratio (r=0.139, p=0.3513), however a strong correlation was found for NFL concentration in serum and NFL concentration in CSF (r=0.6303, p<0.0001). In conclusion, serum NFL appears to be a reliable blood biomarker for neuronal injury, and its concentration is not confounded by BBB permeability.
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Affiliation(s)
- Marie Kalm
- Department of Pharmacology, Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden.
| | - Martina Boström
- Department of Oncology, Institute of Clinical Sciences, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Åsa Sandelius
- Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Yohanna Eriksson
- Department of Pharmacology, Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - C Joakim Ek
- Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Kaj Blennow
- Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden; Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, Mölndal, Sweden
| | - Thomas Björk-Eriksson
- Department of Oncology, Institute of Clinical Sciences, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Henrik Zetterberg
- Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden; Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, Mölndal, Sweden; Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square, London, United Kingdom
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Mottahedin A, Smith PLP, Hagberg H, Ek CJ, Mallard C. TLR2-mediated leukocyte trafficking to the developing brain. J Leukoc Biol 2016; 101:297-305. [DOI: 10.1189/jlb.3a1215-568r] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 06/23/2016] [Accepted: 07/17/2016] [Indexed: 11/24/2022] Open
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Saunders NR, Dziegielewska KM, Unsicker K, Ek CJ. Delayed astrocytic contact with cerebral blood vessels in FGF-2 deficient mice does not compromise permeability properties at the developing blood-brain barrier. Dev Neurobiol 2016; 76:1201-1212. [DOI: 10.1002/dneu.22383] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 02/02/2016] [Indexed: 12/31/2022]
Affiliation(s)
- Norman R. Saunders
- Department of Pharmacology and Therapeutics; University of Melbourne; Australia
| | | | - Klaus Unsicker
- Department of Molecular Embryology; Institute of Anatomy and Cell Biology, University of Freiburg; Freiburg Germany
| | - C. Joakim Ek
- Department of Physiology; Institute for Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg; Gothenburg 40530 Sweden
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Liddelow SA, Dziegielewska KM, Ek CJ, Habgood MD, Bauer H, Bauer HC, Lindsay H, Wakefield MJ, Strazielle N, Kratzer I, Møllgård K, Ghersi-Egea JF, Saunders NR. Correction: Mechanisms That Determine the Internal Environment of the Developing Brain: A Transcriptomic, Functional and Ultrastructural Approach. PLoS One 2016; 11:e0147680. [PMID: 26783757 PMCID: PMC4718702 DOI: 10.1371/journal.pone.0147680] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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D'Angelo B, Ek CJ, Sun Y, Zhu C, Sandberg M, Mallard C. GSK3β inhibition protects the immature brain from hypoxic-ischaemic insult via reduced STAT3 signalling. Neuropharmacology 2015; 101:13-23. [PMID: 26384655 DOI: 10.1016/j.neuropharm.2015.09.017] [Citation(s) in RCA: 33] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Revised: 09/11/2015] [Accepted: 09/14/2015] [Indexed: 02/06/2023]
Abstract
Hypoxic-ischaemic (HI) injury is an important cause of neurological morbidity in neonates. HI leads to pathophysiological responses, including inflammation and oxidative stress that culminate in cell death. Activation of glycogen synthase kinase 3β (GSK3β) and the signal transducer and activator of transcription (STAT3) promotes brain inflammation. The purpose of this study was to test whether inhibition of GSK3β signalling protects against neonatal HI brain injury. Mice were subjected to HI at postnatal day (PND) 9 and treated with a selective GSK3β inhibitor, SB216763. Brain injury and caspase-3 activation, anti-oxidant and inflammatory mRNA responses and activation of STAT3 were analysed. Our results show that HI reduced phosphorylation of GSK3β, thus promoting its kinase activity. The GSK3β inhibitor reduced caspase-3 activation and neuronal cell death elicited by HI and reverted the effects of HI on gene expression of the anti-oxidant enzyme sod2 and mitochondrial factor pgc1α. The HI insult activated STAT3 in glial cells and GSK3β inhibition attenuated STAT3 phosphorylation and its nuclear translocation following HI. Further, GSK3β inhibition reduced HI-induced gene expression of pro-inflammatory cytokines tnfα and Il-6, while promoted the anti-inflammatory factor Il-10. In summary, data show that GSK3β inhibition is neuroprotective in neonatal HI brain injury likely via reduced pro-inflammatory responses by blocking STAT3 signalling. Our study suggests that pharmacological interventions built upon GSK3β silencing strategies could represent a novel therapy in neonatal brain injury.
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Affiliation(s)
- Barbara D'Angelo
- Institute of Neuroscience and Physiology, Department of Physiology, University of Gothenburg, Sweden
| | - C Joakim Ek
- Institute of Neuroscience and Physiology, Department of Physiology, University of Gothenburg, Sweden
| | - Yanyan Sun
- Institute of Neuroscience and Physiology, Department of Clinical Neuroscience, University of Gothenburg, Sweden
| | - Changlian Zhu
- Institute of Neuroscience and Physiology, Department of Clinical Neuroscience, University of Gothenburg, Sweden
| | - Mats Sandberg
- Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Sweden
| | - Carina Mallard
- Institute of Neuroscience and Physiology, Department of Physiology, University of Gothenburg, Sweden.
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15
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Ek CJ, D'Angelo B, Lehner C, Nathanielsz P, Li C, Mallard C. Expression of tight junction proteins and transporters for xenobiotic metabolism at the blood-CSF barrier during development in the nonhuman primate (P. hamadryas). Reprod Toxicol 2015; 56:32-44. [PMID: 26092209 DOI: 10.1016/j.reprotox.2015.06.047] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [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: 03/15/2015] [Revised: 06/04/2015] [Accepted: 06/05/2015] [Indexed: 10/23/2022]
Abstract
The choroid plexus (CP) is rich in barrier mechanisms including transporters and enzymes which can influence drug disposition between blood and brain. We have limited knowledge of their state in fetus. We have studied barrier mechanisms along with metabolism and transporters influencing xenobiotics, using RNAseq and protein analysis, in the CP during the second-half of gestation in a nonhuman primate (Papio hamadryas). There were no differences in the expression of the tight-junctions at the CP suggesting a well-formed fetal blood-CSF barrier during this period of gestation. Further, the fetal CP express many enzymes for phase I-III metabolisms as well as transporters suggesting that it can greatly influence drug disposition and has a significant machinery to deactivate reactive molecules with only minor gestational changes. In summary, the study suggests that from, at least, midgestation, the CP in the nonhuman primate is restrictive and express most known genes associated with barrier function and transport.
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Affiliation(s)
- C Joakim Ek
- Institute for Neuroscience and Physiology, Department of Physiology, Sahlgrenska Academy, University of Gothenburg, 40530 Gothenburg, Sweden.
| | - Barbara D'Angelo
- Institute for Neuroscience and Physiology, Department of Physiology, Sahlgrenska Academy, University of Gothenburg, 40530 Gothenburg, Sweden
| | - Christine Lehner
- Institute of Tendon and Bone Regeneration, Paracelsus Medical University, Spinal Cord Injury and Tissue Regeneration Center Salzburg, Salzburg, Austria; Department of Traumatology and Sports Injuries, Paracelsus Medical University Salzburg, Austria; Austrian Cluster for Tissue Regeneration Vienna, Austria
| | - Peter Nathanielsz
- Wyoming Pregnancy and Life Course Health Center, University of Wyoming, Laramie, WY 82071, United States
| | - Cun Li
- Department of Traumatology and Sports Injuries, Paracelsus Medical University Salzburg, Austria
| | - Carina Mallard
- Institute for Neuroscience and Physiology, Department of Physiology, Sahlgrenska Academy, University of Gothenburg, 40530 Gothenburg, Sweden
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16
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Ek CJ, D'Angelo B, Baburamani AA, Lehner C, Leverin AL, Smith PLP, Nilsson H, Svedin P, Hagberg H, Mallard C. Brain barrier properties and cerebral blood flow in neonatal mice exposed to cerebral hypoxia-ischemia. J Cereb Blood Flow Metab 2015; 35:818-27. [PMID: 25627141 PMCID: PMC4420855 DOI: 10.1038/jcbfm.2014.255] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Revised: 12/05/2014] [Accepted: 12/08/2014] [Indexed: 11/09/2022]
Abstract
Insults to the developing brain often result in irreparable damage resulting in long-term deficits in motor and cognitive functions. The only treatment today for hypoxic-ischemic encephalopathy (HIE) in newborns is hypothermia, which has limited clinical benefit. We have studied changes to the blood-brain barriers (BBB) as well as regional cerebral blood flow (rCBF) in a neonatal model of HIE to further understand the underlying pathologic mechanisms. Nine-day old mice pups, brain roughly equivalent to the near-term human fetus, were subjected to hypoxia-ischemia. Hypoxia-ischemia increased BBB permeability to small and large molecules within hours after the insult, which normalized in the following days. The opening of the BBB was associated with changes to BBB protein expression whereas gene transcript levels were increased showing direct molecular damage to the BBB but also suggesting compensatory mechanisms. Brain pathology was closely related to reductions in rCBF during the hypoxia as well as the areas with compromised BBB showing that these are intimately linked. The transient opening of the BBB after the insult is likely to contribute to the pathology but at the same time provides an opportunity for therapeutics to better reach the infarcted areas in the brain.
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Affiliation(s)
- C Joakim Ek
- Department of Physiology, Institute for Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Barbara D'Angelo
- Department of Physiology, Institute for Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Ana A Baburamani
- 1] Department of Physiology, Institute for Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden [2] Centre for the Developing Brain, Division of Imaging Sciences and Biomedical Engineering, King's College London, King's Health Partners, St. Thomas' Hospital, London, UK
| | - Christine Lehner
- Spinal Cord Injury and Tissue Regeneration Center Salzburg, Department of Traumatology and Sport Injuries, Institute of Tendon and Bone Regeneration, Paracelsus Medical University, Salzburg, Austria; Austrian Cluster for Tissue Regeneration
| | - Anna-Lena Leverin
- Department of Physiology, Institute for Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Peter L P Smith
- Department of Physiology, Institute for Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Holger Nilsson
- Department of Physiology, Institute for Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Pernilla Svedin
- Department of Physiology, Institute for Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Henrik Hagberg
- 1] Centre for the Developing Brain, Division of Imaging Sciences and Biomedical Engineering, King's College London, King's Health Partners, St. Thomas' Hospital, London, UK [2] Departments of Obstetrics and Gynecology, Institute for Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Carina Mallard
- Department of Physiology, Institute for Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
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Bi D, Qiao L, Bergelson I, Ek CJ, Duan L, Zhang X, Albertsson AM, Pettengill M, Kronforst K, Ninkovic J, Goldmann D, Janzon A, Hagberg H, Wang X, Mallard C, Levy O. Staphylococcus epidermidis Bacteremia Induces Brain Injury in Neonatal Mice via Toll-like Receptor 2-Dependent and -Independent Pathways. J Infect Dis 2015; 212:1480-90. [PMID: 25883383 DOI: 10.1093/infdis/jiv231] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [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: 01/14/2015] [Accepted: 04/07/2015] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Staphylococcus epidermidis causes late-onset sepsis in preterm infants. Staphylococcus epidermidis activates host responses in part via Toll-like receptor 2 (TLR2). Epidemiologic studies link bacteremia and neonatal brain injury, but direct evidence is lacking. METHODS Wild-type and TLR2-deficient (TLR2-/-) mice were injected intravenously with S. epidermidis at postnatal day 1 prior to measuring plasma and brain cytokine and chemokine levels, bacterial clearance, brain caspase-3 activation, white/gray matter volume, and innate transcriptome. RESULTS Staphylococcus epidermidis bacteremia spontaneously resolved over 24 hours without detectable bacteria in the cerebrospinal fluid (CSF). TLR2-/- mice demonstrated delayed S. epidermidis clearance from blood, spleen, and liver. Staphylococcus epidermidis increased the white blood cell count in the CSF, increased interleukin 6, interleukin 12p40, CCL2, and CXCL1 concentrations in plasma; increased the CCL2 concentration in the brain; and caused rapid (within 6 hours) TLR2-dependent brain activation of caspase-3 and TLR2-independent white matter injury. CONCLUSIONS Staphylococcus epidermidis bacteremia, in the absence of bacterial entry into the CSF, impairs neonatal brain development. Staphylococcus epidermidis bacteremia induced both TLR2-dependent and -independent brain injury, with the latter occurring in the absence of TLR2, a condition associated with an increased bacterial burden. Our study indicates that the consequences of transient bacteremia in early life may be more severe than commonly appreciated, and our findings may inform novel approaches to reduce bacteremia-associated brain injury.
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Affiliation(s)
- Dan Bi
- Department of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Sweden Department of Pediatrics, Third Affiliated Hospital, Zhengzhou University
| | - Lili Qiao
- Department of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Sweden Department of Pediatrics, Song Jiang Central Hospital, Shanghai, China
| | - Ilana Bergelson
- Division of Infectious Diseases, Department of Medicine, Boston Children's Hospital Harvard Medical School, Boston, Massachusetts
| | - C Joakim Ek
- Department of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Sweden
| | - Luqi Duan
- Department of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Sweden Department of Pediatrics, Third Affiliated Hospital, Zhengzhou University
| | - Xiaoli Zhang
- Department of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Sweden Department of Pediatrics, Third Affiliated Hospital, Zhengzhou University
| | - Anna-Maj Albertsson
- Department of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Sweden
| | - Matthew Pettengill
- Division of Infectious Diseases, Department of Medicine, Boston Children's Hospital Harvard Medical School, Boston, Massachusetts
| | - Kenny Kronforst
- Department of Pediatrics, Division of Neonatology, Lurie Children's Hospital of Chicago and Prentice Women's Hospital, Feinberg School of Medicine, Northwestern University, Illinois
| | - Jana Ninkovic
- 3M Corporate Research Materials Laboratory, St. Paul, Minnesota
| | - Donald Goldmann
- Division of Infectious Diseases, Department of Medicine, Boston Children's Hospital Harvard Medical School, Boston, Massachusetts
| | - Anders Janzon
- Department of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Sweden
| | - Henrik Hagberg
- Department of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Sweden Department of Obstetrics and Gynecology, Sahlgrenska Academy, University of Gothenburg, Sweden Centre for the Developing Brain, Department of Perinatal Imaging and Health, King's College London, United Kingdom
| | - Xiaoyang Wang
- Department of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Sweden Department of Pediatrics, Third Affiliated Hospital, Zhengzhou University
| | - Carina Mallard
- Department of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Sweden Centre for the Developing Brain, Department of Perinatal Imaging and Health, King's College London, United Kingdom
| | - Ofer Levy
- Division of Infectious Diseases, Department of Medicine, Boston Children's Hospital Harvard Medical School, Boston, Massachusetts
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Ek CJ, Nathanielsz P, Li C, Mallard C. Transcriptomal changes and functional annotation of the developing non-human primate choroid plexus. Front Neurosci 2015; 9:82. [PMID: 25814924 PMCID: PMC4357249 DOI: 10.3389/fnins.2015.00082] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [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: 09/29/2014] [Accepted: 02/25/2015] [Indexed: 12/04/2022] Open
Abstract
The choroid plexuses are small organs that protrude into each brain ventricle producing cerebrospinal fluid that constantly bathes the brain. These organs differentiate early in development just after neural closure at a stage when the brain is little vascularized. In recent years the plexus has been shown to have a much more active role in brain development than previously appreciated thereby it can influence both neurogenesis and neural migration by secreting factors into the CSF. However, much of choroid plexus developmental function is still unclear. Most previous studies on this organ have been undertaken in rodents but translation into humans is not straightforward since they have a different timing of brain maturation processes. We have collected choroid plexus from three fetal gestational ages of a non-human primate, the baboon, which has much closer brain development to humans. The transcriptome of the plexuses was determined by next generation sequencing and Ingenuity Pathway Analysis software was used to annotate functions and enrichment of pathways of changes in the transcriptome. The number of unique transcripts decreased with development and the majority of differentially expressed transcripts were down-regulated through development suggesting a more complex and active plexus earlier in fetal development. The functional annotation indicated changes across widespread biological functions in plexus development. In particular we find age-dependent regulation of genes associated with annotation categories: Gene Expression, Development of Cardiovascular System, Nervous System Development and Molecular Transport. Our observations support the idea that the choroid plexus has roles in shaping brain development.
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Affiliation(s)
- C Joakim Ek
- Department of Physiology, Institute for Neuroscience and Physiology, University of Gothenburg, Sahlgrenska Academy Gothenburg, Sweden
| | - Peter Nathanielsz
- Department of Obstetrics, Center for Pregnancy and Newborn Research, The University of Texas Health Science Center San Antonio, TX, USA
| | - Cun Li
- Department of Obstetrics, Center for Pregnancy and Newborn Research, The University of Texas Health Science Center San Antonio, TX, USA
| | - Carina Mallard
- Department of Physiology, Institute for Neuroscience and Physiology, University of Gothenburg, Sahlgrenska Academy Gothenburg, Sweden
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Saunders NR, Noor NM, Dziegielewska KM, Wheaton BJ, Liddelow SA, Steer DL, Ek CJ, Habgood MD, Wakefield MJ, Lindsay H, Truettner J, Miller RD, Smith AI, Dietrich WD. Age-dependent transcriptome and proteome following transection of neonatal spinal cord of Monodelphis domestica (South American grey short-tailed opossum). PLoS One 2014; 9:e99080. [PMID: 24914927 PMCID: PMC4051688 DOI: 10.1371/journal.pone.0099080] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Accepted: 05/09/2014] [Indexed: 01/08/2023] Open
Abstract
This study describes a combined transcriptome and proteome analysis of Monodelphis domestica response to spinal cord injury at two different postnatal ages. Previously we showed that complete transection at postnatal day 7 (P7) is followed by profuse axon growth across the lesion with near-normal locomotion and swimming when adult. In contrast, at P28 there is no axon growth across the lesion, the animals exhibit weight-bearing locomotion, but cannot use hind limbs when swimming. Here we examined changes in gene and protein expression in the segment of spinal cord rostral to the lesion at 24 h after transection at P7 and at P28. Following injury at P7 only forty genes changed (all increased expression); most were immune/inflammatory genes. Following injury at P28 many more genes changed their expression and the magnitude of change for some genes was strikingly greater. Again many were associated with the immune/inflammation response. In functional groups known to be inhibitory to regeneration in adult cords the expression changes were generally muted, in some cases opposite to that required to account for neurite inhibition. For example myelin basic protein expression was reduced following injury at P28 both at the gene and protein levels. Only four genes from families with extracellular matrix functions thought to influence neurite outgrowth in adult injured cords showed substantial changes in expression following injury at P28: Olfactomedin 4 (Olfm4, 480 fold compared to controls), matrix metallopeptidase (Mmp1, 104 fold), papilin (Papln, 152 fold) and integrin α4 (Itga4, 57 fold). These data provide a resource for investigation of a priori hypotheses in future studies of mechanisms of spinal cord regeneration in immature animals compared to lack of regeneration at more mature stages.
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Affiliation(s)
- Norman R. Saunders
- Department of Pharmacology & Therapeutics, The University of Melbourne, Victoria, Australia
- * E-mail:
| | - Natassya M. Noor
- Department of Pharmacology & Therapeutics, The University of Melbourne, Victoria, Australia
| | | | - Benjamin J. Wheaton
- Department of Pharmacology & Therapeutics, The University of Melbourne, Victoria, Australia
| | - Shane A. Liddelow
- Department of Pharmacology & Therapeutics, The University of Melbourne, Victoria, Australia
- Department of Neurobiology, Stanford University, Stanford, California, United States of America
| | - David L. Steer
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - C. Joakim Ek
- Department of Neuroscience and Physiology, University of Gothenburg, Gothenburg, Sweden
| | - Mark D. Habgood
- Department of Pharmacology & Therapeutics, The University of Melbourne, Victoria, Australia
| | - Matthew J. Wakefield
- Walter & Eliza Hall Institute of Medical Research, Victoria, Australia
- Department of Genetics, The University of Melbourne, Victoria, Australia
| | - Helen Lindsay
- Walter & Eliza Hall Institute of Medical Research, Victoria, Australia
- Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
| | - Jessie Truettner
- The Miami Project to Cure Paralysis, University of Miami, Miller School of Medicine, Miami, Florida, United States of America
| | - Robert D. Miller
- Center for Evolutionary & Theoretical Immunology, Department of Biology, University of New Mexico, Albuquerque, New Mexico, United States of America
| | - A. Ian Smith
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - W. Dalton Dietrich
- The Miami Project to Cure Paralysis, University of Miami, Miller School of Medicine, Miami, Florida, United States of America
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Bolouri H, Sävman K, Wang W, Thomas A, Maurer N, Dullaghan E, Fjell CD, Ek CJ, Hagberg H, Hancock REW, Brown KL, Mallard C. Innate defense regulator peptide 1018 protects against perinatal brain injury. Ann Neurol 2014; 75:395-410. [DOI: 10.1002/ana.24087] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Revised: 09/20/2013] [Accepted: 12/03/2013] [Indexed: 12/24/2022]
Affiliation(s)
- Hayde Bolouri
- Institute of Neuroscience and Physiology; Department of Physiology, Sahlgrenska Academy, University of Gothenburg; Gothenburg Sweden
| | - Karin Sävman
- Institute of Neuroscience and Physiology; Department of Physiology, Sahlgrenska Academy, University of Gothenburg; Gothenburg Sweden
- Department of Pediatrics, Sahlgrenska Academy; University of Gothenburg; Gothenburg Sweden
| | - Wei Wang
- Institute of Neuroscience and Physiology; Department of Physiology, Sahlgrenska Academy, University of Gothenburg; Gothenburg Sweden
| | - Anitha Thomas
- Centre for Drug Research and Development; Vancouver, British Columbia; Canada
| | - Norbert Maurer
- Centre for Drug Research and Development; Vancouver, British Columbia; Canada
| | - Edie Dullaghan
- Centre for Drug Research and Development; Vancouver, British Columbia; Canada
| | - Christopher D. Fjell
- James Hogg Research Centre; University of British Columbia at St Paul's Hospital; Vancouver British Columbia Canada
| | - C. Joakim Ek
- Institute of Neuroscience and Physiology; Department of Physiology, Sahlgrenska Academy, University of Gothenburg; Gothenburg Sweden
| | - Henrik Hagberg
- Perinatal Center, Department of Clinical Sciences; Sahlgrenska Academy, University of Gothenburg; Gothenburg Sweden
- Centre for the Developing Brain, King's College; Perinatal Imaging and Health, St Thomas' Hospital; London United Kingdom
| | - Robert E. W. Hancock
- James Hogg Research Centre; University of British Columbia at St Paul's Hospital; Vancouver British Columbia Canada
| | - Kelly L. Brown
- Department of Rheumatology and Inflammation Research; Sahlgrenska Academy, University of Gothenburg; Gothenburg Sweden
| | - Carina Mallard
- Institute of Neuroscience and Physiology; Department of Physiology, Sahlgrenska Academy, University of Gothenburg; Gothenburg Sweden
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Liddelow SA, Dziegielewska KM, Ek CJ, Habgood MD, Bauer H, Bauer HC, Lindsay H, Wakefield MJ, Strazielle N, Kratzer I, Møllgård K, Ghersi-Egea JF, Saunders NR. Mechanisms that determine the internal environment of the developing brain: a transcriptomic, functional and ultrastructural approach. PLoS One 2013; 8:e65629. [PMID: 23843944 PMCID: PMC3699566 DOI: 10.1371/journal.pone.0065629] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2013] [Accepted: 04/25/2013] [Indexed: 01/04/2023] Open
Abstract
We provide comprehensive identification of embryonic (E15) and adult rat lateral ventricular choroid plexus transcriptome, with focus on junction-associated proteins, ionic influx transporters and channels. Additionally, these data are related to new structural and previously published permeability studies. Results reveal that most genes associated with intercellular junctions are expressed at similar levels at both ages. In total, 32 molecules known to be associated with brain barrier interfaces were identified. Nine claudins showed unaltered expression, while two claudins (6 and 8) were expressed at higher levels in the embryo. Expression levels for most cytoplasmic/regulatory adaptors (10 of 12) were similar at the two ages. A few junctional genes displayed lower expression in embryos, including 5 claudins, occludin and one junctional adhesion molecule. Three gap junction genes were enriched in the embryo. The functional effectiveness of these junctions was assessed using blood-delivered water-soluble tracers at both the light and electron microscopic level: embryo and adult junctions halted movement of both 286Da and 3kDa molecules into the cerebrospinal fluid (CSF). The molecular identities of many ion channel and transporter genes previously reported as important for CSF formation and secretion in the adult were demonstrated in the embryonic choroid plexus (and validated with immunohistochemistry of protein products), but with some major age-related differences in expression. In addition, a large number of previously unidentified ion channel and transporter genes were identified for the first time in plexus epithelium. These results, in addition to data obtained from electron microscopical and physiological permeability experiments in immature brains, indicate that exchange between blood and CSF is mainly transcellular, as well-formed tight junctions restrict movement of small water-soluble molecules from early in development. These data strongly indicate the brain develops within a well-protected internal environment and the exchange between the blood, brain and CSF is transcellular and not through incomplete barriers.
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Affiliation(s)
- Shane A Liddelow
- Department of Pharmacology, the University of Melbourne, Victoria, Australia.
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D’Angelo B, Ek CJ, Sandberg M, Mallard C. Expression of the Nrf2-system at the blood-CSF barrier is modulated by neonatal inflammation and hypoxia-ischemia. J Inherit Metab Dis 2013; 36:479-90. [PMID: 23109062 PMCID: PMC3664399 DOI: 10.1007/s10545-012-9551-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Revised: 09/14/2012] [Accepted: 10/10/2012] [Indexed: 12/20/2022]
Abstract
Transcription factor NF-E2-related factor-2 (Nrf2) is a key regulator of endogenous anti-oxidant systems shown to play a neuroprotective role in the adult by preserving blood-brain barrier function. The choroid plexus, site for the blood-CSF barrier, has been suggested to be particularly important in maintaining brain barrier function in development. We investigated the expression of Nrf2- and detoxification-system genes in choroid plexus following systemic LPS injections, unilateral cerebral hypoxia-ischemia (HI) as well as the combination of LPS and HI (LPS/HI). Plexuses were collected at different time points after LPS, HI and LPS/HI in 9-day old mice. mRNA levels of Nrf2 and many of its target genes were analyzed by quantitative PCR. Cell death was analyzed by caspase-3 immunostaining and TUNEL. LPS caused down-regulation of the Nrf2-system genes while HI increased expression at earlier time points. LPS exposure prior to HI prevented many of the HI-induced gene increases. None of the insults resulted in any apparent cell death to choroidal epithelium. These data imply that the function of the inducible anti-oxidant system in the choroid plexus is down-regulated by inflammation, even if choroid cells are not structurally damaged. Further, LPS prevented the endogenous antioxidant response following HI, suggesting the possibility that the choroid plexus may be at risk if LPS is united with an insult that increases oxidative stress such as hypoxia-ischemia.
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Affiliation(s)
- Barbara D’Angelo
- Department of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - C. Joakim Ek
- Department of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Mats Sandberg
- Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Carina Mallard
- Department of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
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Baburamani AA, Ek CJ, Walker DW, Castillo-Melendez M. Vulnerability of the developing brain to hypoxic-ischemic damage: contribution of the cerebral vasculature to injury and repair? Front Physiol 2012; 3:424. [PMID: 23162470 PMCID: PMC3493883 DOI: 10.3389/fphys.2012.00424] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [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: 08/15/2012] [Accepted: 10/17/2012] [Indexed: 11/13/2022] Open
Abstract
As clinicians attempt to understand the underlying reasons for the vulnerability of different regions of the developing brain to injury, it is apparent that little is known as to how hypoxia-ischemia may affect the cerebrovasculature in the developing infant. Most of the research investigating the pathogenesis of perinatal brain injury following hypoxia-ischemia has focused on excitotoxicity, oxidative stress and an inflammatory response, with the response of the developing cerebrovasculature receiving less attention. This is surprising as the presentation of devastating and permanent injury such as germinal matrix-intraventricular haemorrhage (GM-IVH) and perinatal stroke are of vascular origin, and the origin of periventricular leukomalacia (PVL) may also arise from poor perfusion of the white matter. This highlights that cerebrovasculature injury following hypoxia could primarily be responsible for the injury seen in the brain of many infants diagnosed with hypoxic-ischemic encephalopathy (HIE). Interestingly the highly dynamic nature of the cerebral blood vessels in the fetus, and the fluctuations of cerebral blood flow and metabolic demand that occur following hypoxia suggest that the response of blood vessels could explain both regional protection and vulnerability in the developing brain. However, research into how blood vessels respond following hypoxia-ischemia have mostly been conducted in adult models of ischemia or stroke, further highlighting the need to investigate how the developing cerebrovasculature responds and the possible contribution to perinatal brain injury following hypoxia. This review discusses the current concepts on the pathogenesis of perinatal brain injury, the development of the fetal cerebrovasculature and the blood brain barrier (BBB), and key mediators involved with the response of cerebral blood vessels to hypoxia.
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Affiliation(s)
- Ana A Baburamani
- The Ritchie Centre, Monash Medical Centre, Monash Institute of Medical Research, Clayton Melbourne, VIC, Australia ; Sahlgrenska Academy, Gothenburg University Göteborg, Sweden
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Ek CJ, Dziegielewska KM, Habgood MD, Saunders NR. Barriers in the developing brain and Neurotoxicology. Neurotoxicology 2011; 33:586-604. [PMID: 22198708 DOI: 10.1016/j.neuro.2011.12.009] [Citation(s) in RCA: 147] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2011] [Revised: 12/11/2011] [Accepted: 12/11/2011] [Indexed: 01/16/2023]
Abstract
The brain develops and grows within a well-controlled internal environment that is provided by cellular exchange mechanisms in the interfaces between blood, cerebrospinal fluid and brain. These are generally referred to by the term "brain barriers": blood-brain barrier across the cerebral endothelial cells and blood-CSF barrier across the choroid plexus epithelial cells. An essential component of barrier mechanisms is the presence of tight junctions between the endothelial and epithelial cells of these interfaces. This review outlines historical evidence for the presence of effective barrier mechanisms in the embryo and newborn and provides an up to date description of recent morphological, biochemical and molecular data for the functional effectiveness of these barriers. Intercellular tight junctions between cerebral endothelial cells and between choroid plexus epithelial cells are functionally effective as soon as they differentiate. Many of the influx and efflux mechanisms are not only present from early in development, but the genes for some are expressed at much higher levels in the embryo than in the adult and there is physiological evidence that these transport systems are functionally more active in the developing brain. This substantial body of evidence supporting the concept of well developed barrier mechanisms in the developing brain is contrasted with the widespread belief amongst neurotoxicologists that "the" blood-brain barrier is immature or even absent in the embryo and newborn. A proper understanding of the functional capacity of the barrier mechanisms to restrict the entry of harmful substances or administered therapeutics into the developing brain is critical. This knowledge would assist the clinical management of pregnant mothers and newborn infants and development of protocols for evaluation of risks of drugs used in pregnancy and the neonatal period prior to their introduction into clinical practice.
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Affiliation(s)
- C Joakim Ek
- Department of Pharmacology, University of Melbourne, Parkville, Victoria 3010, Australia
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Noor NM, Steer DL, Wheaton BJ, Ek CJ, Truettner JS, Dietrich WD, Dziegielewska KM, Richardson SJ, Smith AI, VandeBerg JL, Saunders NR. Age-dependent changes in the proteome following complete spinal cord transection in a postnatal South American opossum (Monodelphis domestica). PLoS One 2011; 6:e27465. [PMID: 22110655 PMCID: PMC3217969 DOI: 10.1371/journal.pone.0027465] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Accepted: 10/17/2011] [Indexed: 12/15/2022] Open
Abstract
Recovery from severe spinal injury in adults is limited, compared to immature animals who demonstrate some capacity for repair. Using laboratory opossums (Monodelphis domestica), the aim was to compare proteomic responses to injury at two ages: one when there is axonal growth across the lesion and substantial behavioural recovery and one when no axonal growth occurs. Anaesthetized pups at postnatal day (P) 7 or P28 were subjected to complete transection of the spinal cord at thoracic level T10. Cords were collected 1 or 7 days after injury and from age-matched controls. Proteins were separated based on isoelectric point and subunit molecular weight; those whose expression levels changed following injury were identified by densitometry and analysed by mass spectrometry. Fifty-six unique proteins were identified as differentially regulated in response to spinal transection at both ages combined. More than 50% were cytoplasmic and 70% belonged to families of proteins with characteristic binding properties. Proteins were assigned to groups by biological function including regulation (40%), metabolism (26%), inflammation (19%) and structure (15%). More changes were detected at one than seven days after injury at both ages. Seven identified proteins: 14-3-3 epsilon, 14-3-3 gamma, cofilin, alpha enolase, heart fatty acid binding protein (FABP3), brain fatty acid binding protein (FABP7) and ubiquitin demonstrated age-related differential expression and were analysed by qRT-PCR. Changes in mRNA levels for FABP3 at P7+1day and ubiquitin at P28+1day were statistically significant. Immunocytochemical staining showed differences in ubiquitin localization in younger compared to older cords and an increase in oligodendrocyte and neuroglia immunostaining following injury at P28. Western blot analysis supported proteomic results for ubiquitin and 14-3-3 proteins. Data obtained at the two ages demonstrated changes in response to injury, compared to controls, that were different for different functional protein classes. Some may provide targets for novel drug or gene therapies.
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Affiliation(s)
- Natassya M. Noor
- Department of Pharmacology, the University of Melbourne, Parkville, Victoria, Australia
| | - David L. Steer
- Department of Biochemistry & Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - Benjamin J. Wheaton
- Department of Pharmacology, the University of Melbourne, Parkville, Victoria, Australia
| | - C. Joakim Ek
- Department of Pharmacology, the University of Melbourne, Parkville, Victoria, Australia
| | - Jessie S. Truettner
- The Miami Project to Cure Paralysis, University of Miami, Miller School of Medicine, Miami, Florida, United States of America
| | - W. Dalton Dietrich
- The Miami Project to Cure Paralysis, University of Miami, Miller School of Medicine, Miami, Florida, United States of America
| | | | - Samantha J. Richardson
- School of Medical Sciences and Health Innovations Research Institute, RMIT University, Bundoora, Victoria, Australia
| | - A. Ian Smith
- Department of Biochemistry & Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - John L. VandeBerg
- Texas Biomedical Research Institute, San Antonio, Texas, United States of America
| | - Norman R. Saunders
- Department of Pharmacology, the University of Melbourne, Parkville, Victoria, Australia
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Wheaton BJ, Callaway JK, Ek CJ, Dziegielewska KM, Saunders NR. Spontaneous development of full weight-supported stepping after complete spinal cord transection in the neonatal opossum, Monodelphis domestica. PLoS One 2011; 6:e26826. [PMID: 22073202 PMCID: PMC3206848 DOI: 10.1371/journal.pone.0026826] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Accepted: 10/04/2011] [Indexed: 01/11/2023] Open
Abstract
Spinal cord trauma in the adult nervous system usually results in permanent loss of function below the injury level. The immature spinal cord has greater capacity for repair and can develop considerable functionality by adulthood. This study used the marsupial laboratory opossum Monodelphis domestica, which is born at a very early stage of neural development. Complete spinal cord transection was made in the lower-thoracic region of pups at postnatal-day 7 (P7) or P28, and the animals grew to adulthood. Injury at P7 resulted in a dense neuronal tissue bridge that connected the two ends of the cord; retrograde neuronal labelling indicated that supraspinal and propriospinal innervation spanned the injury site. This repair was associated with pronounced behavioural recovery, coordinated gait and an ability to use hindlimbs when swimming. Injury at P28 resulted in a cyst-like cavity encased in scar tissue forming at the injury site. Using retrograde labelling, no labelled brainstem or propriospinal neurons were found above the lesion, indicating that detectable neuronal connectivity had not spanned the injury site. However, these animals could use their hindlimbs to take weight-supporting steps but could not use their hindlimbs when swimming. White matter, demonstrated by Luxol Fast Blue staining, was present in the injury site of P7- but not P28-injured animals. Overall, these studies demonstrated that provided spinal injury occurs early in development, regrowth of supraspinal innervation is possible. This repair appears to lead to improved functional outcomes. At older ages, even without detectable axonal growth spanning the injury site, substantial development of locomotion was still possible. This outcome is discussed in conjunction with preliminary findings of differences in the local propriospinal circuits following spinal cord injury (demonstrated with fluororuby labelling), which may underlie the weight bearing locomotion observed in the apparent absence of axons bridging the lesion site in P28-injured Monodelphis.
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Affiliation(s)
- Benjamin J. Wheaton
- Department of Pharmacology, The University of Melbourne, Parkville, Victoria, Australia
| | - Jennifer K. Callaway
- Department of Pharmacology, The University of Melbourne, Parkville, Victoria, Australia
| | - C. Joakim Ek
- Department of Pharmacology, The University of Melbourne, Parkville, Victoria, Australia
| | | | - Norman R. Saunders
- Department of Pharmacology, The University of Melbourne, Parkville, Victoria, Australia
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Saunders NR, Ek CJ, Habgood MD, Johansson P, Liddelow S, Dziegielewska KM. Assessing blood-cerebrospinal fluid barrier permeability in the rat embryo. Methods Mol Biol 2011; 686:247-65. [PMID: 21082375 DOI: 10.1007/978-1-60761-938-3_11] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
The rat is a useful model for studies of embryonic blood-CSF function in that the embryos are large enough to collect sufficient fluid samples for analysis and exteriorized embryos can be kept viable for several hours in order to conduct longer term experiments. Both quantitative and qualitative methods that are similar to those used in adult studies can be used to assess blood-CSF function in the rat embryo; however, there are technical aspects of these studies that are more challenging. The choice of the methods to be used depends largely on the question being asked. This chapter describes in detail the precise steps that need to be taken to keep rat embryos in a good physiological state while conducting the experiments, how to administer markers into the embryonic circulation, and how to sample blood and/or CSF from embryos. How to evaluate the results obtained is outlined at the end of each method, together with notes on some limitations that are inherent in developmental studies.
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Affiliation(s)
- Norman R Saunders
- Department of Pharmacology, University of Melbourne, Parkville, Victoria, Australia
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Ek CJ, Habgood MD, Callaway JK, Dennis R, Dziegielewska KM, Johansson PA, Potter A, Wheaton B, Saunders NR. Spatio-temporal progression of grey and white matter damage following contusion injury in rat spinal cord. PLoS One 2010; 5:e12021. [PMID: 20711496 PMCID: PMC2918504 DOI: 10.1371/journal.pone.0012021] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2010] [Accepted: 07/12/2010] [Indexed: 12/20/2022] Open
Abstract
Cellular mechanisms of secondary damage progression following spinal cord injury remain unclear. We have studied the extent of tissue damage from 15 min to 10 weeks after injury using morphological and biochemical estimates of lesion volume and surviving grey and white matter. This has been achieved by semi-quantitative immunocytochemical methods for a range of cellular markers, quantitative counts of white matter axonal profiles in semi-thin sections and semi-quantitative Western blot analysis, together with behavioural tests (BBB scores, ledged beam, random rung horizontal ladder and DigiGait™ analysis). We have developed a new computer-controlled electronic impactor based on a linear motor that allows specification of the precise nature, extent and timing of the impact. Initial (15 min) lesion volumes showed very low variance (1.92±0.23 mm3, mean±SD, n = 5). Although substantial tissue clearance continued for weeks after injury, loss of grey matter was rapid and complete by 24 hours, whereas loss of white matter extended up to one week. No change was found between one and 10 weeks after injury for almost all morphological and biochemical estimates of lesion size or behavioural methods. These results suggest that previously reported apparent ongoing injury progression is likely to be due, to a large extent, to clearance of tissue damaged by the primary impact rather than continuing cell death. The low variance of the impactor and the comprehensive assessment methods described in this paper provide an improved basis on which the effects of potential treatment regimes for spinal cord injury can be assessed.
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Affiliation(s)
- C. Joakim Ek
- Department of Pharmacology, University of Melbourne, Parkville, Victoria, Australia
| | - Mark D. Habgood
- Department of Pharmacology, University of Melbourne, Parkville, Victoria, Australia
| | - Jennifer K. Callaway
- Department of Pharmacology, University of Melbourne, Parkville, Victoria, Australia
| | - Ross Dennis
- Department of Pharmacology, University of Melbourne, Parkville, Victoria, Australia
| | | | - Pia A. Johansson
- Department of Pharmacology, University of Melbourne, Parkville, Victoria, Australia
| | - Ann Potter
- Department of Pharmacology, University of Melbourne, Parkville, Victoria, Australia
| | - Benjamin Wheaton
- Department of Pharmacology, University of Melbourne, Parkville, Victoria, Australia
| | - Norman R. Saunders
- Department of Pharmacology, University of Melbourne, Parkville, Victoria, Australia
- * E-mail:
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Ek CJ, Wong A, Liddelow SA, Johansson PA, Dziegielewska KM, Saunders NR. Efflux mechanisms at the developing brain barriers: ABC-transporters in the fetal and postnatal rat. Toxicol Lett 2010; 197:51-9. [PMID: 20466047 DOI: 10.1016/j.toxlet.2010.04.025] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2010] [Revised: 04/28/2010] [Accepted: 04/29/2010] [Indexed: 11/29/2022]
Abstract
Proteins of the ATP-binding cassette (ABC) family, present at the blood-brain barrier interfaces, have been shown to reduce the entry of compounds from blood into the brain by active efflux. Their substrates are diverse including many drugs and toxins and therefore provide an important mechanism for brain neuroprotection. However, knowledge of their presence and function in the developing brain is very limited. We have used qPCR and immunocytochemistry to determine gene expression and localisation of four main barrier ABC-transporters (pgp/ABCB1, MRP1/ABCC1, MRP4/ABCC4 and BCRP/ABCG2) in the fetal and neonatal rat brain cerebral blood vessels (site of blood-brain barrier) and choroid plexus (site of blood-CSF barrier). The study shows that ABC-transporters localise to the brain barriers even at early fetal stages and although pgp expression was lower in the fetus, the other transporters were expressed at comparable levels in fetal and adult brains suggesting direct neuroprotection of the brain in addition to that provided by the placenta. BCRP was expressed at higher levels in developing choroid plexus and was only detected at fetal stages on the blood-facing side of epithelial cells indicating a particular role of this transporter for early brain efflux mechanisms.
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Affiliation(s)
- C Joakim Ek
- Department of Pharmacology, University of Melbourne, Parkville, Australia.
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Saunders NR, Joakim Ek C, Dziegielewska KM. The neonatal blood-brain barrier is functionally effective, and immaturity does not explain differential targeting of AAV9. Nat Biotechnol 2009; 27:804-5; author reply 805. [PMID: 19741632 DOI: 10.1038/nbt0909-804] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Liddelow SA, Dziegielewska KM, Ek CJ, Johansson PA, Potter AM, Saunders NR. Cellular transfer of macromolecules across the developing choroid plexus of Monodelphis domestica. Eur J Neurosci 2009; 29:253-66. [PMID: 19200232 DOI: 10.1111/j.1460-9568.2008.06571.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Choroid plexus epithelial cells secrete cerebrospinal fluid (CSF) and transfer molecules from blood into CSF. Tight junctions between choroidal epithelial cells are functionally effective from early in development: the route of transfer is suggested to be transcellular. Routes of transfer for endogenous and exogenous plasma proteins and dextrans were studied in Monodelphis domestica (opossum). Pups at postnatal (P) days 1-65 and young adults were injected with biotinylated dextrans (3-70 kDa) and/or foetal protein fetuin. CSF, plasma and brain samples were collected from terminally anaesthetized animals. Choroid plexus cells containing plasma proteins were detected immunocytochemically. Numbers of plasma protein-positive epithelial cells increased to adult levels by P28, but their percentage of plexus cells declined. Numbers of cells positive for biotinylated probes increased with age, while their percentage remained constant. Colocalization studies showed specificity for individual proteins in some epithelial cells. Biotinylated probes and endogenous proteins colocalized in about 10% of cells in younger animals, increasing towards 100% by adulthood. Injections of markers into the ventricles demonstrated that protein is transferred only from blood into CSF, whereas dextrans pass in both directions. These results indicate that protein and lipid-insoluble markers are transferred by separate mechanisms present in choroid plexuses from the earliest stage of brain development, and transfer of proteins from plasma across choroid plexus epithelial cells contributes to the high protein concentration in CSF in the immature brain.
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Affiliation(s)
- Shane A Liddelow
- Department of Pharmacology, The University of Melbourne, Parkville, Victoria 3010, Australia
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Stolp HB, Ek CJ, Johansson PA, Dziegielewska KM, Bethge N, Wheaton BJ, Potter AM, Saunders NR. Factors involved in inflammation-induced developmental white matter damage. Neurosci Lett 2009; 451:232-6. [PMID: 19152829 DOI: 10.1016/j.neulet.2009.01.021] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2008] [Revised: 11/28/2008] [Accepted: 01/08/2009] [Indexed: 01/14/2023]
Abstract
Developmental white matter damage is a brain pathology associated with several long-term neurological disorders. An inflammatory insult has been suggested as the major instigating event. This study investigated the relative influence of inflammation, blood-brain barrier permeability and glial ontogeny in white matter damage. Systemic inflammation was induced in Monodelphis domestica (opossum) by serial intraperitoneal injections of lipopolysaccharide at different stages of brain development. Volume of white matter was estimated for the external capsule. Blood-brain barrier permeability was assessed immunocytochemically. Quantitative RT-PCR was used to measure relative levels of mRNA for IL-1beta, IL-6 and COX-2. Developmental changes in numbers and appearance of microglia and astrocytes were estimated. Results showed that in response to systemic inflammation, white matter was reduced in the external capsule during a circumscribed period only. At the same developmental stage blood-brain barrier permeability was altered, cerebral inflammatory response was present and numbers of microglia increased. However, the periods of altered blood-brain barrier permeability and the cerebral inflammatory response were longer than the period of the external capsule's susceptibility to white matter damage, which coincided with the developmental increase in the number of astrocytes in this tract. Thus, the mechanism of white matter damage following systemic inflammation is multifactorial, including cerebral inflammation and breakdown of brain barriers occurring simultaneously at specific stages of glial cell development.
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Affiliation(s)
- Helen B Stolp
- Department of Pharmacology, University of Melbourne, Parkville, VIC 3010, Australia.
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Lane MA, Truettner JS, Brunschwig JP, Gomez A, Bunge MB, Dietrich WD, Dziegielewska KM, Ek CJ, Vandeberg JL, Saunders NR. Age-related differences in the local cellular and molecular responses to injury in developing spinal cord of the opossum, Monodelphis domestica. Eur J Neurosci 2007; 25:1725-42. [PMID: 17432961 DOI: 10.1111/j.1460-9568.2007.05439.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Immature spinal cord, unlike adult, has an ability to repair itself following injury. Evidence for regeneration, structural repair and development of substantially normal locomotor behaviour comes from studies of marsupials due to their immaturity at birth. We have compared morphological, cellular and molecular changes in spinal cords transected at postnatal day (P)7 or P14, from 3 h to 2 weeks post-injury, in South American opossums (Monodelphis domestica). A bridge between severed ends of cords was apparent 5 days post-injury in P7 cords, compared to 2 weeks in P14. The volume of neurofilament (axonal) material in the bridge 2 weeks after injury was 30% of control in P7- but < 10% in P14-injured cords. Granulocytes accumulated at the site of injury earlier (3 h) in P7 than in P14 (24 h)-injured animals. Monocytes accumulated 24 h post-injury and accumulation was greater in P14 cords. Accumulation of GFAP-positive astrocytes at the lesion occurred earlier in P14-injured cords. Neurites and growth cones were identified ultrastructurally in contact with astrocytes forming the bridge. Results using mouse inflammatory gene arrays showed differences in levels of expression of many TGF, TNF, cytokine, chemokine and interleukin gene families. Most of the genes identified were up-regulated to a greater extent following injury at P7. Some changes were validated and quantified by RT-PCR. Overall, the results suggest that at least some of the greater ability to recover from spinal cord transection at P7 compared to P14 in opossums is due to differences in inflammatory cellular and molecular responses.
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Affiliation(s)
- M A Lane
- Department of Pharmacology & Centre for Neuroscience, University of Melbourne, Victoria, Australia
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Habgood MD, Bye N, Dziegielewska KM, Ek CJ, Lane MA, Potter A, Morganti-Kossmann C, Saunders NR. Changes in blood-brain barrier permeability to large and small molecules following traumatic brain injury in mice. Eur J Neurosci 2007; 25:231-8. [PMID: 17241284 DOI: 10.1111/j.1460-9568.2006.05275.x] [Citation(s) in RCA: 169] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The entry of therapeutic compounds into the brain and spinal cord is normally restricted by barrier mechanisms in cerebral blood vessels (blood-brain barrier) and choroid plexuses (blood-CSF barrier). In the injured brain, ruptured cerebral blood vessels circumvent these barrier mechanisms by allowing blood contents to escape directly into the brain parenchyma. This process may contribute to the secondary damage that follows the initial primary injury. However, this localized compromise of barrier function in the injured brain may also provide a 'window of opportunity' through which drugs that do not normally cross the blood-brain barriers are able to do so. This paper describes a systematic study of barrier permeability in a mouse model of traumatic brain injury using both small and large inert molecules that can be visualized or quantified. The results show that soon after trauma, both large and small molecules are able to enter the brain in and around the injury site. Barrier restriction to large (protein-sized) molecules is restored by 4-5 h after injury. In contrast, smaller molecules (286-10,000 Da) are still able to enter the brain as long as 4 days postinjury. Thus the period of potential secondary damage from barrier disruption and the period during which therapeutic compounds have direct access to the injured brain may be longer than previously thought.
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Affiliation(s)
- M D Habgood
- Victorian Neurotrauma Research Group, Department of Pharmacology, Centre for Neuroscience, University of Melbourne, Parkville, Victoria 3010, Australia.
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Abstract
Blood-cerebrospinal fluid (CSF) barrier function and expansion of the ventricular system were investigated in embryonic rats (E12-18). Permeability markers (sucrose and inulin) were injected intraperitoneally and concentrations measured in plasma and CSF at two sites (lateral and 4th ventricles) after 1 h. Total protein concentrations were also measured. CSF/plasma concentration ratios for endogenous protein were stable at approximately 20% at E14-18 and subsequently declined. In contrast, ratios for sucrose (100%) and inulin (40%) were highest at the earliest ages studied (E13-14) and then decreased substantially. Between E13 and E16 the volume of the lateral ventricles increased over three-fold. Decreasing CSF/plasma concentration ratios for small, passively diffusing molecules during embryonic development may not reflect changes in permeability. Instead, increasing volume of distribution appears to be important in this decline. The intracellular presence of a small marker (3000 Da biotin-dextranamine) in plexus epithelial cells following intraperitoneal injection indicates a transcellular route of transfer. Ultrastructural evidence confirmed that choroid plexus tight junctions are impermeable to small molecules at least as early as E15, indicating the blood-CSF barrier is morphologically and functionally mature early in embryonic development. Comparison of two albumins (human and bovine) showed that transfer of human albumin (surrogate for endogenous protein) was 4-5 times greater than bovine, indicating selective blood-to-CSF transfer. The number of plexus epithelial cells immunopositive for endogenous plasma protein increased in parallel with increases in total protein content of the expanding ventricular system. Results suggest that different transcellular mechanisms for protein and small molecule transfer are operating across the embryonic blood-CSF interface.
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Affiliation(s)
- P A Johansson
- Department of Pharmacology & Centre for Neuroscience, University of Melbourne, Parkville, Victoria 3010, Australia
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Stolp HB, Dziegielewska KM, Ek CJ, Potter AM, Saunders NR. Long-term changes in blood-brain barrier permeability and white matter following prolonged systemic inflammation in early development in the rat. Eur J Neurosci 2006; 22:2805-16. [PMID: 16324115 DOI: 10.1111/j.1460-9568.2005.04483.x] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Epidemiological evidence in human fetuses links inflammation during development with white matter damage. Breakdown of the blood-brain barrier has been proposed as a possible mechanism. This was investigated in the present study by inducing a prolonged inflammatory response in newborn rats, with intraperitoneal injections of lipopolysaccharide (LPS; 0.2 mg/kg) given at postnatal (P) day 0, P2, P4, P6 and P8. An acute phase response was present over the whole period of injections. Changes in blood-brain barrier permeability were determined for small (sucrose and inulin) and large (protein) molecules. During and immediately after the inflammatory response, plasma proteins were detected in the brain only within white matter tracts, indicating an increased permeability of the blood-brain barrier to protein during this period. The alteration in permeability to protein was transient. In contrast, the permeability of the blood-brain barrier to 14C-sucrose and 14C-inulin was significantly higher in adult animals that had received serial LPS injections during development. Adult animals receiving a single 1 mg/kg LPS injection at P0 showed no alteration in blood-brain barrier permeability to either small or larger molecules. A significant decrease in the volume of CNPase immunoreactive presumptive white matter tracts occurred in the external capsule and corpus callosum at P9. These results demonstrate that a prolonged systemic inflammatory response in the early postnatal period in rats causes size selective increases in blood-brain barrier permeability at different stages of brain development and results in changes in white matter volume.
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Affiliation(s)
- H B Stolp
- Department of Pharmacology, University of Melbourne, Parkville, VIC 3010, Australia
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Johansson PA, Dziegielewska KM, Ek CJ, Habgood MD, Møllgård K, Potter A, Schuliga M, Saunders NR. Aquaporin-1 in the choroid plexuses of developing mammalian brain. Cell Tissue Res 2005; 322:353-64. [PMID: 16133142 DOI: 10.1007/s00441-005-1120-x] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2004] [Accepted: 03/23/2005] [Indexed: 11/29/2022]
Abstract
The normal brain develops within a well-controlled stable internal "milieu" protected by specialised mechanisms referred to collectively as blood-brain barriers. A fundamental feature of this environment is the control of water flow in and out of the developing brain. Because of limited vascularisation of the immature brain, choroid plexuses, via the cerebrospinal fluid, have been proposed as the main route of fluid exchange between the blood and brain interfaces. We describe the temporal expression and appearance of aquaporin-1 (AQP1) which is important for water transfer across adult choroid plexuses. AQP1 expression was studied in rat embryos using real time reverse transcription/polymerase chain reaction. mRNA for AQP1 was present in rat brain at embryonic day 12 (E12) one day before the protein was detectable in the fourth ventricular choroid plexus (the first plexus to appear); its relative levels increased at E13-E14 when more AQP1-immunoreactive cells appeared in all plexuses. The presence of AQP1 was determined immunocytochemically in five different mammalian species (rat, mouse, human, sheep and opossum) in all four choroid plexuses from their earliest appearance. In all five species studied, the appearance of AQP1 immunoreactivity followed the same developmental sequence: the fourth, lateral and, finally, third ventricular choroid plexus. The stage of choroid plexus development when AQP1 was first detected in all five species and in all four choroid plexuses corresponded to the transition between Stages I and II. The cellular localisation of AQP1 in all choroid plexuses, as soon as it was detectable, had the characteristic apical membrane distribution previously described in the adult; a basolateral membrane localisation was also observed.
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Affiliation(s)
- P A Johansson
- Department of Pharmacology and Centre for Neuroscience, University of Melbourne, Parkville, Victoria, 3010, Australia
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Stolp HB, Dziegielewska KM, Ek CJ, Habgood MD, Lane MA, Potter AM, Saunders NR. Breakdown of the blood-brain barrier to proteins in white matter of the developing brain following systemic inflammation. Cell Tissue Res 2005; 320:369-78. [PMID: 15846513 DOI: 10.1007/s00441-005-1088-6] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2004] [Accepted: 01/21/2005] [Indexed: 10/25/2022]
Abstract
Compromised blood-brain barrier permeability resulting from systemic inflammation has been implicated as a possible cause of brain damage in fetuses and newborns and may underlie white matter damage later in life. Rats at postnatal day (P) 0, P8 and P20 and opossums (Monodelphis domestica) at P15, P20, P35, P50 and P60 and adults of both species were injected intraperitoneally with 0.2-10 mg/kg body weight of 055:B5 lipopolysaccharide. An acute-phase response occurred in all animals. A change in the permeability of the blood-brain barrier to plasma proteins during a restricted period of postnatal development in both species was determined immunocytochemically by the presence of proteins surrounding cerebral blood vessels and in brain parenchyma. Blood vessels in white matter, but not grey matter, became transiently permeable to proteins between 10 and 24 h after lipopolysaccharide injection in P0 and P8 rats and P35-P60 opossums. Brains of Monodelphis younger than P35, rats older than P20 and adults of both species were not affected. Permeability of the blood-cerebrospinal fluid (CSF) barrier to proteins was not affected by systemic inflammation for at least 48 h after intraperitoneal injection of lipopolysaccharide. These results show that there is a restricted period in brain development when the blood-brain barrier, but not the blood-CSF barrier, to proteins is susceptible to systemic inflammation; this does not appear to be attributable to barrier "immaturity" but to its stage of development and only occurs in white matter.
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Affiliation(s)
- H B Stolp
- Department of Pharmacology, University of Melbourne, Parkville, Victoria, 3010, Australia
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Ek CJ, Habgood MD, Dziegielewska KM, Potter A, Saunders NR. Permeability and route of entry for lipid-insoluble molecules across brain barriers in developing Monodelphis domestica. J Physiol 2001; 536:841-53. [PMID: 11691876 PMCID: PMC2278913 DOI: 10.1111/j.1469-7793.2001.00841.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
1. We have studied the permeability of blood-brain barriers to small molecules such as [(14)C]sucrose, [(3)H]inulin, [(14)C]L-glucose and [(3)H]glycerol from early stages of development (postnatal day 6, P6) in South American opossums (Monodelphis domestica), using a litter-based method for estimating steady-state cerebrospinal fluid (CSF)/plasma and brain/plasma ratios of markers that were injected I.P. 2. Steady-state ratios for L-glucose, sucrose and inulin all showed progressive decreases during development. The rate of uptake of L-glucose into the brain and CSF, in short time course experiments (7-24 min) when age-related differences in CSF production can be considered negligible also decreased during development. These results indicate that there is a significant decrease in the permeability of brain barriers to small lipid-insoluble molecules during brain development. 3. The steady-state blood/CSF ratio for 3000 Da lysine-fixable biotin-dextran following I.P. injection was shown to be consistent with diffusion from blood to CSF. It was therefore used to visualise the route of penetration for small lipid-insoluble molecules across brain barriers at P0-30. The proportion of biotin-dextran-positive cells in the choroid plexuses declined in parallel with the age-related decline in permeability to the small-molecular-weight markers; the paracellular (tight junction) pathway for biotin-dextran appeared to be blocked, but biotin-dextran was easily detectable in the CSF. A transcellular route from blood to CSF was suggested by the finding that some choroid plexus epithelial cells contained biotin-dextran. 4. Biotin-dextran was also taken up by cerebral endothelial cells in the youngest brains studied (P0), but in contrast to the CSF, could not be detected in the brain extracellular space (i.e. a significant blood-brain barrier to small-sized lipid-insoluble compounds was already present). However, in immature brains (P0-13) biotin-dextran was taken up by some cells in the brain. These cells generally had contact with the CSF, suggesting that it is likely to have been the source of their biotin-dextran. Since the quantitative permeability data suggest that biotin-dextran behaves similarly to the radiolabelled markers used in this study, it is suggested that these markers in the more immature brains were also present intracellularly. Thus, brain/plasma ratios may be a misleading indicator of blood-brain barrier permeability in very immature animals. 5. The immunocytochemical staining for biotin-dextran in the CSF, in contrast to the lack of staining in the brain extracellular space, together with the quantitative permeability data showing that the radiolabelled markers penetrated more rapidly and to a much higher steady-state level in CSF than in the brain, suggests that lipid-insoluble molecules such as sucrose and inulin reach the immature brain predominantly via the CSF rather than directly across the very few blood vessels that are present at that time.
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Affiliation(s)
- C J Ek
- Department of Anatomy and Physiology, University of Tasmania, Hobart, Tasmania 7001, Australia
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