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| 2. |
- Zhou, K., et al.
(författare)
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Radiation induces progenitor cell death, microglia activation, and blood-brain barrier damage in the juvenile rat cerebellum
- 2017
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Posterior fossa tumors are the most common childhood intracranial tumors, and radiotherapy is one of the most effective treatments. However, irradiation induces long-term adverse effects that can have significant negative impacts on the patient's quality of life. The purpose of this study was to characterize irradiation-induced cellular and molecular changes in the cerebellum. We found that irradiation-induced cell death occurred mainly in the external germinal layer (EGL) of the juvenile rat cerebellum. The number of proliferating cells in the EGL decreased, and 82.9% of them died within 24 h after irradiation. Furthermore, irradiation induced oxidative stress, microglia accumulation, and inflammation in the cerebellum. Interestingly, blood-brain barrier damage and blood flow reduction was considerably more pronounced in the cerebellum compared to other brain regions. The cerebellar volume decreased by 39% and the migration of proliferating cells to the internal granule layer decreased by 87.5% at 16 weeks after irradiation. In the light of recent studies demonstrating that the cerebellum is important not only for motor functions, but also for cognition, and since treatment of posterior fossa tumors in children typically results in debilitating cognitive deficits, this differential susceptibility of the cerebellum to irradiation should be taken into consideration for future protective strategies.
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| 3. |
- Ek, C. Joakim, et al.
(författare)
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Expression of tight junction proteins and transporters for xenobiotic metabolism at the blood-CSF barrier during development in the nonhuman primate (P. hamadryas)
- 2015
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Ingår i: Reproductive Toxicology. - : Elsevier BV. - 0890-6238. ; 56, s. 32-44
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Tidskriftsartikel (refereegranskat)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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| 4. |
- Lehner, C., et al.
(författare)
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The blood-tendon barrier: Identification and characterisation of a novel tissue barrier in tendon blood vessels
- 2016
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Ingår i: European Cells and Materials. - 1473-2262. ; 31, s. 296-311
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Tidskriftsartikel (refereegranskat)abstract
- Tissue barriers function as “gate keepers” between different compartments (usually blood and tissue) and are formed by specialised membrane-associated proteins, localising to the apicolateral plasma membrane domain of epithelial and endothelial cells. By sealing the paracellular space, the free diffusion of solutes and molecules across epithelia and endothelia is impeded. Thereby, tissue barriers contribute to the establishment and maintenance of a distinct internal and external environment, which is crucial during organ development and allows maintenance of an organ-specific homeostatic milieu. So far, various epithelial and endothelial tissue barriers have been described, including the blood-brain barrier, the blood-retina barrier, the blood-testis barrier, the blood-placenta barrier, and the cerebrospinal fluid (CSF)-brain barrier, which are vital for physiological function and any disturbance of these barriers can result in severe organ damage or even death. Here, we describe the identification of a novel barrier, located in the vascular bed of tendons, which we term the blood-tendon barrier (BTB). By using immunohistochemistry, transmission electron microscopy, and tracer studies we demonstrate the presence of a functional endothelial barrier within tendons restricting the passage of large blood-borne molecules into the surrounding tendon tissue. We further provide in vitro evidence that the BTB potentially contributes to the creation of a distinct internal tissue environment impacting upon the proliferation and differentiation of tendon-resident cells, effects which might be fundamental for the onset of tendon pathologies. © 2016, AO Research Institute. All rights reserved.
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| 5. |
- Ek, C. Joakim, et al.
(författare)
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Brain barrier properties and cerebral blood flow in neonatal mice exposed to cerebral hypoxia-ischemia
- 2015
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Ingår i: Journal of Cerebral Blood Flow and Metabolism. - : SAGE Publications. - 0271-678X .- 1559-7016. ; 35:5, s. 818-827
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Tidskriftsartikel (refereegranskat)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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| 6. |
- Ek, C. Joakim, et al.
(författare)
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Transcriptomal changes and functional annotation of the developing non-human primate choroid plexus
- 2015
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Ingår i: Frontiers in Neuroscience. - : Frontiers Media SA. - 1662-453X. ; 9
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Tidskriftsartikel (refereegranskat)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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| 7. |
- Liddelow, S. A., et al.
(författare)
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Mechanisms That Determine the Internal Environment of the Developing Brain: A Transcriptomic, Functional and Ultrastructural Approach
- 2013
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Ingår i: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 8:7
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Tidskriftsartikel (refereegranskat)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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| 8. |
- Anderberg, Rozita H, 1976, et al.
(författare)
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Treatment with RNase alleviates brain injury but not neuroinflammation in neonatal hypoxia/ischemia
- 2024
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Ingår i: JOURNAL OF NEUROSCIENCE RESEARCH. - 0360-4012 .- 1097-4547. ; 102:4
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Tidskriftsartikel (refereegranskat)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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| 9. |
- Andersson, E. Axel, et al.
(författare)
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Circulating tight-junction proteins are potential biomarkers for blood-brain barrier function in a model of neonatal hypoxic/ischemic brain injury
- 2021
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Ingår i: Fluids and Barriers of the CNS. - : Springer Science and Business Media LLC. - 2045-8118. ; 18:1
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Tidskriftsartikel (refereegranskat)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 C-14-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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| 10. |
- Andersson, E. Axel, et al.
(författare)
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Function and Biomarkers of the Blood-Brain Barrier in a Neonatal Germinal Matrix Haemorrhage Model
- 2021
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Ingår i: Cells. - : MDPI AG. - 2073-4409. ; 10:7
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Tidskriftsartikel (refereegranskat)abstract
- Germinal matrix haemorrhage (GMH), caused by rupturing blood vessels in the germinal matrix, is a prevalent driver of preterm brain injuries and death. Our group recently developed a model simulating GMH using intrastriatal injections of collagenase in 5-day-old rats, which corresponds to the brain development of human preterm infants. This study aimed to define changes to the blood-brain barrier (BBB) and to evaluate BBB proteins as biomarkers in this GMH model. Regional BBB functions were investigated using blood to brain C-14-sucrose uptake as well as using biotinylated BBB tracers. Blood plasma and cerebrospinal fluids were collected at various times after GMH and analysed with ELISA for OCLN and CLDN5. The immunoreactivity of BBB proteins was assessed in brain sections. Tracer experiments showed that GMH produced a defined region surrounding the hematoma where many vessels lost their integrity. This region expanded for at least 6 h following GMH, thereafter resolution of both hematoma and re-establishment of BBB function occurred. The sucrose experiment indicated that regions somewhat more distant to the hematoma also exhibited BBB dysfunction; however, BBB function was normalised within 5 days of GMH. This shows that GMH leads to a temporal dysfunction in the BBB that may be important in pathological processes as well as in connection to therapeutic interventions. We detected an increase of tight-junction proteins in both CSF and plasma after GMH making them potential biomarkers for GMH.
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