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Immune response in the eye following epileptic seizures

Ahl, Matilda LU ; Avdic, Una LU ; Skoug, Cecilia; Ali, Idrish LU ; Chugh, Deepti LU ; Johansson, Ulrica Englund LU and Ekdahl Clementson, Christine LU (2016) In Journal of Neuroinflammation 13(1).
Abstract

Background: Epileptic seizures are associated with an immune response in the brain. However, it is not known whether it can extend to remote areas of the brain, such as the eyes. Hence, we investigated whether epileptic seizures induce inflammation in the retina. Methods: Adult rats underwent electrically induced temporal status epilepticus, and the eyes were studied 6 h, 1, and 7 weeks later with biochemical and immunohistochemical analyses. An additional group of animals received CX3CR1 antibody intracerebroventricularly for 6 weeks after status epilepticus. Results: Biochemical analyses and immunohistochemistry revealed no increased cell death and unaltered expression of several immune-related cytokines and chemokines as well as no... (More)

Background: Epileptic seizures are associated with an immune response in the brain. However, it is not known whether it can extend to remote areas of the brain, such as the eyes. Hence, we investigated whether epileptic seizures induce inflammation in the retina. Methods: Adult rats underwent electrically induced temporal status epilepticus, and the eyes were studied 6 h, 1, and 7 weeks later with biochemical and immunohistochemical analyses. An additional group of animals received CX3CR1 antibody intracerebroventricularly for 6 weeks after status epilepticus. Results: Biochemical analyses and immunohistochemistry revealed no increased cell death and unaltered expression of several immune-related cytokines and chemokines as well as no microglial activation, 6 h post-status epilepticus compared to non-stimulated controls. At 1 week, again, retinal cytoarchitecture appeared normal and there was no cell death or micro- or macroglial reaction, apart from a small decrease in interleukin-10. However, at 7 weeks, even if the cytoarchitecture remained normal and no ongoing cell death was detected, the numbers of microglia were increased ipsi- and contralateral to the epileptic focus. The microglia remained within the synaptic layers but often in clusters and with more processes extending into the outer nuclear layer. Morphological analyses revealed a decrease in surveying and an increase in activated microglia. In addition, increased levels of the chemokine KC/GRO and cytokine interleukin-1β were found. Furthermore, macroglial activation was noted in the inner retina. No alterations in numbers of phagocytic cells, infiltrating macrophages, or vascular pericytes were observed. Post-synaptic density-95 cluster intensity was reduced in the outer nuclear layer, reflecting seizure-induced synaptic changes without disrupted cytoarchitecture in areas with increased microglial activation. The retinal gliosis was decreased by a CX3CR1 immune modulation known to reduce gliosis within epileptic foci, suggesting a common immunological reaction. Conclusions: Our results are the first evidence that epileptic seizures induce an immune response in the retina. It has a potential to become a novel non-invasive tool for detecting brain inflammation through the eyes.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Astrocytes, Brain, Epilepsy, Inflammation, Microglia, Retina
in
Journal of Neuroinflammation
volume
13
issue
1
publisher
BioMed Central
external identifiers
  • Scopus:84975873883
ISSN
1742-2094
DOI
10.1186/s12974-016-0618-3
language
English
LU publication?
yes
id
46819802-ad7c-48ef-9f35-b48c5e9ff381
date added to LUP
2016-07-18 14:14:07
date last changed
2016-10-30 04:48:55
@misc{46819802-ad7c-48ef-9f35-b48c5e9ff381,
  abstract     = {<p>Background: Epileptic seizures are associated with an immune response in the brain. However, it is not known whether it can extend to remote areas of the brain, such as the eyes. Hence, we investigated whether epileptic seizures induce inflammation in the retina. Methods: Adult rats underwent electrically induced temporal status epilepticus, and the eyes were studied 6 h, 1, and 7 weeks later with biochemical and immunohistochemical analyses. An additional group of animals received CX3CR1 antibody intracerebroventricularly for 6 weeks after status epilepticus. Results: Biochemical analyses and immunohistochemistry revealed no increased cell death and unaltered expression of several immune-related cytokines and chemokines as well as no microglial activation, 6 h post-status epilepticus compared to non-stimulated controls. At 1 week, again, retinal cytoarchitecture appeared normal and there was no cell death or micro- or macroglial reaction, apart from a small decrease in interleukin-10. However, at 7 weeks, even if the cytoarchitecture remained normal and no ongoing cell death was detected, the numbers of microglia were increased ipsi- and contralateral to the epileptic focus. The microglia remained within the synaptic layers but often in clusters and with more processes extending into the outer nuclear layer. Morphological analyses revealed a decrease in surveying and an increase in activated microglia. In addition, increased levels of the chemokine KC/GRO and cytokine interleukin-1β were found. Furthermore, macroglial activation was noted in the inner retina. No alterations in numbers of phagocytic cells, infiltrating macrophages, or vascular pericytes were observed. Post-synaptic density-95 cluster intensity was reduced in the outer nuclear layer, reflecting seizure-induced synaptic changes without disrupted cytoarchitecture in areas with increased microglial activation. The retinal gliosis was decreased by a CX3CR1 immune modulation known to reduce gliosis within epileptic foci, suggesting a common immunological reaction. Conclusions: Our results are the first evidence that epileptic seizures induce an immune response in the retina. It has a potential to become a novel non-invasive tool for detecting brain inflammation through the eyes.</p>},
  author       = {Ahl, Matilda and Avdic, Una and Skoug, Cecilia and Ali, Idrish and Chugh, Deepti and Johansson, Ulrica Englund and Ekdahl Clementson, Christine},
  issn         = {1742-2094},
  keyword      = {Astrocytes,Brain,Epilepsy,Inflammation,Microglia,Retina},
  language     = {eng},
  month        = {06},
  number       = {1},
  publisher    = {ARRAY(0xa87ee00)},
  series       = {Journal of Neuroinflammation},
  title        = {Immune response in the eye following epileptic seizures},
  url          = {http://dx.doi.org/10.1186/s12974-016-0618-3},
  volume       = {13},
  year         = {2016},
}