151
|
Hurtado-Alvarado G, Cabañas-Morales AM, Gómez-Gónzalez B. Pericytes: brain-immune interface modulators. Front Integr Neurosci 2014; 7:80. [PMID: 24454281 PMCID: PMC3887314 DOI: 10.3389/fnint.2013.00080] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Accepted: 12/26/2013] [Indexed: 01/08/2023] Open
Abstract
The premise that the central nervous system is immune-privileged arose from the fact that direct contact between immune and nervous cells is hindered by the blood-brain barrier. However, the blood-brain barrier also comprises the interface between the immune and nervous systems by secreting chemo-attractant molecules and by modulating immune cell entry into the brain. The majority of published studies on the blood-brain barrier focus on endothelial cells (ECs), which are a critical component, but not the only one; other cellular components include astroglia, microglia, and pericytes. Pericytes are poorly studied in comparison with astrocytes or ECs; they are mesenchymal cells that can modify their ultrastructure and gene expression in response to changes in the central nervous system microenvironment. Pericytes have a unique synergistic relationship with brain ECs in the regulation of capillary permeability through secretion of cytokines, chemokines, nitric oxide, matrix metalloproteinases, and by means of capillary contraction. Those pericyte manifestations are related to changes in blood-brain barrier permeability by an increase in endocytosis-mediated transport and by tight junction disruption. In addition, recent reports demonstrate that pericytes control the migration of leukocytes in response to inflammatory mediators by up-regulating the expression of adhesion molecules and releasing chemo-attractants; however, under physiological conditions they appear to be immune-suppressors. Better understanding of the immune properties of pericytes and their participation in the effects of brain infections, neurodegenerative diseases, and sleep loss will be achieved by analyzing pericyte ultrastructure, capillary coverage, and protein expression. That knowledge may provide a mechanism by which pericytes participate in the maintenance of the proper function of the brain-immune interface.
Collapse
Affiliation(s)
| | | | - Beatriz Gómez-Gónzalez
- Area of Neurosciences, Department of Biology of Reproduction, Unidad Iztapalapa, Universidad Autónoma MetropolitanaMexico City, Mexico
| |
Collapse
|
152
|
Yang J, Wang G, Gao C, Shao G, Kang N. Effects of hyperbaric oxygen on MMP-2 and MMP-9 expression and spinal cord edema after spinal cord injury. Life Sci 2013. [DOI: 10.1016/j.lfs.2013.10.015] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
153
|
Raha AA, Vaishnav RA, Friedland RP, Bomford A, Raha-Chowdhury R. The systemic iron-regulatory proteins hepcidin and ferroportin are reduced in the brain in Alzheimer's disease. Acta Neuropathol Commun 2013; 1:55. [PMID: 24252754 PMCID: PMC3893417 DOI: 10.1186/2051-5960-1-55] [Citation(s) in RCA: 142] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Accepted: 08/25/2013] [Indexed: 12/11/2022] Open
Abstract
Background The pathological features of the common neurodegenerative conditions, Alzheimer’s disease (AD), Parkinson’s disease and multiple sclerosis are all known to be associated with iron dysregulation in regions of the brain where the specific pathology is most highly expressed. Iron accumulates in cortical plaques and neurofibrillary tangles in AD where it participates in redox cycling and causes oxidative damage to neurons. To understand these abnormalities in the distribution of iron the expression of proteins that maintain systemic iron balance was investigated in human AD brains and in the APP-transgenic (APP-tg) mouse. Results Protein levels of hepcidin, the iron-homeostatic peptide, and ferroportin, the iron exporter, were significantly reduced in hippocampal lysates from AD brains. By histochemistry, hepcidin and ferroportin were widely distributed in the normal human brain and co-localised in neurons and astrocytes suggesting a role in regulating iron release. In AD brains, hepcidin expression was reduced and restricted to the neuropil, blood vessels and damaged neurons. In the APP-tg mouse immunoreactivity for ferritin light-chain, the iron storage isoform, was initially distributed throughout the brain and as the disease progressed accumulated in the core of amyloid plaques. In human and mouse tissues, extensive AD pathology with amyloid plaques and severe vascular damage with loss of pericytes and endothelial disruption was seen. In AD brains, hepcidin and ferroportin were associated with haem-positive granular deposits in the region of damaged blood vessels. Conclusion Our results suggest that the reduction in ferroportin levels are likely associated with cerebral ischaemia, inflammation, the loss of neurons due to the well-characterised protein misfolding, senile plaque formation and possibly the ageing process itself. The reasons for the reduction in hepcidin levels are less clear but future investigation could examine circulating levels of the peptide in AD and a possible reduction in the passage of hepcidin across damaged vascular endothelium. Imbalance in the levels and distribution of ferritin light-chain further indicate a failure to utilize and release iron by damaged and degenerating neurons.
Collapse
|
154
|
Radu BM, Bramanti P, Osculati F, Flonta ML, Radu M, Bertini G, Fabene PF. Neurovascular unit in chronic pain. Mediators Inflamm 2013; 2013:648268. [PMID: 23840097 PMCID: PMC3687484 DOI: 10.1155/2013/648268] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Accepted: 05/08/2013] [Indexed: 12/27/2022] Open
Abstract
Chronic pain is a debilitating condition with major socioeconomic impact, whose neurobiological basis is still not clear. An involvement of the neurovascular unit (NVU) has been recently proposed. In particular, the blood-brain barrier (BBB) and blood-spinal cord barrier (BSCB), two NVU key players, may be affected during the development of chronic pain; in particular, transient permeabilization of the barrier is suggested by several inflammatory- and nerve-injury-based pain models, and we argue that the clarification of molecular BBB/BSCB permeabilization events will shed new light in understanding chronic pain mechanisms. Possible biases in experiments supporting this theory and its translational potentials are discussed. Moving beyond an exclusive focus on the role of the endothelium, we propose that our understanding of the mechanisms subserving chronic pain will benefit from the extension of research efforts to the NVU as a whole. In this view, the available evidence on the interaction between analgesic drugs and the NVU is here reviewed. Chronic pain comorbidities, such as neuroinflammatory and neurodegenerative diseases, are also discussed in view of NVU changes, together with innovative pharmacological solutions targeting NVU components in chronic pain treatment.
Collapse
Affiliation(s)
- Beatrice Mihaela Radu
- Department of Neurological, Neuropsychological, Morphological and Movement Sciences, Section of Anatomy and Histology, University of Verona, Strada Le Grazie 8, 37134 Verona, Italy
- Department of Anatomy, Animal Physiology and Biophysics, Faculty of Biology, University of Bucharest, 050095 Bucharest, Romania
| | | | | | - Maria-Luisa Flonta
- Department of Anatomy, Animal Physiology and Biophysics, Faculty of Biology, University of Bucharest, 050095 Bucharest, Romania
| | - Mihai Radu
- Department of Neurological, Neuropsychological, Morphological and Movement Sciences, Section of Anatomy and Histology, University of Verona, Strada Le Grazie 8, 37134 Verona, Italy
- Department of Life and Environmental Physics, “Horia Hulubei” National Institute for Physics and Nuclear Engineering, 077125 Bucharest-Magurele, Romania
| | - Giuseppe Bertini
- Department of Neurological, Neuropsychological, Morphological and Movement Sciences, Section of Anatomy and Histology, University of Verona, Strada Le Grazie 8, 37134 Verona, Italy
| | - Paolo Francesco Fabene
- Department of Neurological, Neuropsychological, Morphological and Movement Sciences, Section of Anatomy and Histology, University of Verona, Strada Le Grazie 8, 37134 Verona, Italy
| |
Collapse
|
155
|
Abbott NJ. Blood-brain barrier structure and function and the challenges for CNS drug delivery. J Inherit Metab Dis 2013; 36:437-49. [PMID: 23609350 DOI: 10.1007/s10545-013-9608-0] [Citation(s) in RCA: 557] [Impact Index Per Article: 50.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Revised: 04/02/2013] [Accepted: 04/03/2013] [Indexed: 12/12/2022]
Abstract
The neurons of the central nervous system (CNS) require precise control of their bathing microenvironment for optimal function, and an important element in this control is the blood-brain barrier (BBB). The BBB is formed by the endothelial cells lining the brain microvessels, under the inductive influence of neighbouring cell types within the 'neurovascular unit' (NVU) including astrocytes and pericytes. The endothelium forms the major interface between the blood and the CNS, and by a combination of low passive permeability and presence of specific transport systems, enzymes and receptors regulates molecular and cellular traffic across the barrier layer. A number of methods and models are available for examining BBB permeation in vivo and in vitro, and can give valuable information on the mechanisms by which therapeutic agents and constructs permeate, ways to optimize permeation, and implications for drug discovery, delivery and toxicity. For treating lysosomal storage diseases (LSDs), models can be included that mimic aspects of the disease, including genetically-modified animals, and in vitro models can be used to examine the effects of cells of the NVU on the BBB under pathological conditions. For testing CNS drug delivery, several in vitro models now provide reliable prediction of penetration of drugs including large molecules and artificial constructs with promising potential in treating LSDs. For many of these diseases it is still not clear how best to deliver appropriate drugs to the CNS, and a concerted approach using a variety of models and methods can give critical insights and indicate practical solutions.
Collapse
Affiliation(s)
- N Joan Abbott
- BBB Group, Institute of Pharmaceutical Science, King's College London, London, UK.
| |
Collapse
|
156
|
Takeda S, Sato N, Ikimura K, Nishino H, Rakugi H, Morishita R. Increased blood-brain barrier vulnerability to systemic inflammation in an Alzheimer disease mouse model. Neurobiol Aging 2013; 34:2064-70. [PMID: 23561508 DOI: 10.1016/j.neurobiolaging.2013.02.010] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2012] [Revised: 01/20/2013] [Accepted: 02/15/2013] [Indexed: 01/05/2023]
Abstract
Behavioral and psychological problems are often observed in patients with dementia such as that associated with Alzheimer disease, and these noncognitive symptoms place an extremely heavy burden on the family and caregivers. Although it is well know that these symptoms often are triggered by infection of peripheral organs, the underlying mechanisms for these pathological conditions are still unclear. In this study, using an Alzheimer amyloid precursor protein (APP)-transgenic mouse, we analyzed behavioral changes and brain inflammatory response induced by peripheral administration of lipopolysaccharide. Application of a unique in vivo microdialysis system revealed that the increase in brain inflammatory cytokine (interleukin-6) level was significantly higher in APP-Tg than in wild-type mice after peripheral lipopolysaccharide injection, which was associated with more severe sickness behaviors. The blood-brain barrier became more permeable in APP-Tg mice during peripherally evoked inflammation, suggesting the increased vulnerability of the blood-brain barrier to inflammation in this animal model of Alzheimer's disease. These findings might provide insight into the pathogenesis of noncognitive symptoms in dementia and a basis to develop new therapeutic treatments for them.
Collapse
Affiliation(s)
- Shuko Takeda
- Department of Clinical Gene Therapy, Graduate School of Medicine, Osaka University, Yamadaoka, Suita, Japan
| | | | | | | | | | | |
Collapse
|
157
|
Zlokovic BV. A gliovascular idea for the white matter repair? J Neurochem 2013; 125:172-4. [PMID: 23441580 DOI: 10.1111/jnc.12174] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Accepted: 01/28/2013] [Indexed: 12/23/2022]
Affiliation(s)
- Berislav V Zlokovic
- Center for Neurodegeneration and Regeneration, Zilkha Neurogenetic Institute, and Department of Physiology and Biophysics, University of Southern California, Los Angeles, CA, USA
| |
Collapse
|
158
|
Winkler EA, Sengillo JD, Sullivan JS, Henkel JS, Appel SH, Zlokovic BV. Blood-spinal cord barrier breakdown and pericyte reductions in amyotrophic lateral sclerosis. Acta Neuropathol 2013; 125:111-20. [PMID: 22941226 PMCID: PMC3535352 DOI: 10.1007/s00401-012-1039-8] [Citation(s) in RCA: 234] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Revised: 08/21/2012] [Accepted: 08/23/2012] [Indexed: 12/12/2022]
Abstract
The blood-brain barrier and blood-spinal cord barrier (BSCB) limit the entry of plasma components and erythrocytes into the central nervous system (CNS). Pericytes play a key role in maintaining blood-CNS barriers. The BSCB is damaged in patients with amyotrophic lateral sclerosis (ALS). Moreover, transgenic ALS rodents and pericyte-deficient mice develop BSCB disruption with erythrocyte extravasation preceding motor neuron dysfunction. Here, we studied whether BSCB disruption with erythrocyte extravasation and pericyte loss are present in human ALS. We show that 11 of 11 cervical cords from ALS patients, but 0 of 5 non-neurodegenerative disorders controls, possess perivascular deposits of erythrocyte-derived hemoglobin and hemosiderin typically 10-50 μm in diameter suggestive of erythrocyte extravasation. Immunostaining for CD235a, a specific marker for erythrocytes, confirmed sporadic erythrocyte extravasation in ALS, but not controls. Quantitative analysis revealed a 3.1-fold increase in perivascular hemoglobin deposits in ALS compared to controls showing hemoglobin confined within the vascular lumen, which correlated with 2.5-fold increase in hemosiderin deposits (r = 0.82, p < 0.01). Spinal cord parenchymal accumulation of plasma-derived immunoglobulin G, fibrin and thrombin was demonstrated in ALS, but not controls. Immunostaining for platelet-derived growth factor receptor-β, a specific marker for CNS pericytes, indicated a 54 % (p < 0.01) reduction in pericyte number in ALS patients compared to controls. Pericyte reduction correlated negatively with the magnitude of BSCB damage as determined by hemoglobin abundance (r = -0.75, p < 0.01). Thus, the BSCB disruption with erythrocyte extravasation and pericyte reductions is present in ALS. Whether similar findings occur in motor cortex and affected brainstem motor nuclei remain to be seen.
Collapse
Affiliation(s)
- Ethan A. Winkler
- Center for Neurodegeneration and Regeneration, Zilkha Neurogenetic Institute, University of Southern California, Room: 101, 1501 San Pablo Street, Los Angeles, CA 90089 USA
| | - Jesse D. Sengillo
- Center for Neurodegeneration and Regeneration, Zilkha Neurogenetic Institute, University of Southern California, Room: 101, 1501 San Pablo Street, Los Angeles, CA 90089 USA
| | - John S. Sullivan
- Center for Neurodegeneration and Regeneration, Zilkha Neurogenetic Institute, University of Southern California, Room: 101, 1501 San Pablo Street, Los Angeles, CA 90089 USA
| | - Jenny S. Henkel
- Department of Neurology, Methodist Neurological Institute, The Methodist Hospital Research Institute, The Methodist Hospital, Houston, TX USA
| | - Stanley H. Appel
- Department of Neurology, Methodist Neurological Institute, The Methodist Hospital Research Institute, The Methodist Hospital, Houston, TX USA
| | - Berislav V. Zlokovic
- Center for Neurodegeneration and Regeneration, Zilkha Neurogenetic Institute, University of Southern California, Room: 101, 1501 San Pablo Street, Los Angeles, CA 90089 USA
| |
Collapse
|
159
|
Sengillo JD, Winkler EA, Walker CT, Sullivan JS, Johnson M, Zlokovic BV. Deficiency in mural vascular cells coincides with blood-brain barrier disruption in Alzheimer's disease. Brain Pathol 2012; 23:303-10. [PMID: 23126372 DOI: 10.1111/bpa.12004] [Citation(s) in RCA: 389] [Impact Index Per Article: 32.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2012] [Accepted: 10/30/2012] [Indexed: 12/13/2022] Open
Abstract
Neurovascular dysfunction contributes to Alzheimer's disease (AD). Cerebrovascular abnormalities and blood-brain barrier (BBB) damage have been shown in AD. The BBB dysfunction can lead to leakage of potentially neurotoxic plasma components in brain that may contribute to neuronal injury. Pericytes are integral in maintaining the BBB integrity. Pericyte-deficient mice develop a chronic BBB damage preceding neuronal injury. Moreover, loss of pericytes was associated with BBB breakdown in patients with amyotrophic lateral sclerosis. Here, we demonstrate a decrease in mural vascular cells in AD, and show that pericyte number and coverage in the cortex and hippocampus of AD subjects compared with neurologically intact controls are reduced by 59% and 60% (P < 0.01), and 32% and 33% (P < 0.01), respectively. An increase in extravascular immunoglobulin G (IgG) and fibrin deposition correlated with reductions in pericyte coverage in AD cases compared with controls; the Pearson's correlation coefficient r for the magnitude of BBB breakdown to IgG and fibrin vs. reduction in pericyte coverage was -0.96 (P < 0.01) and -0.81 (P < 0.01) in the cortex, respectively, and -0.86 (P < 0.01) and -0.98 (P < 0.01) in the hippocampus, respectively. Thus, deficiency in mural vascular cells may contribute to disrupted vascular barrier properties and resultant neuronal dysfunction during AD pathogenesis.
Collapse
Affiliation(s)
- Jesse D Sengillo
- Center for Neurodegeneration and Regeneration, Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, CA, USA
| | | | | | | | | | | |
Collapse
|