title: Immune response in the eye following epileptic seizures.
abstract: 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.
  
  
  
  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.
  
  
  
  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.
  
  
  
  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.
authors.affiliation: Inflammation and Stem Cell Therapy Group, Division of Clinical Neurophysiology, Lund University, BMC A11, Sölvegatan 17, SE-221 84, Lund, Sweden.|Lund Epilepsy Center, Lund University, SE-221 85, Lund, Sweden.
authors.forename: Matilda
authors.initials: M
authors.lastname: Ahl
authors.affiliation: Inflammation and Stem Cell Therapy Group, Division of Clinical Neurophysiology, Lund University, BMC A11, Sölvegatan 17, SE-221 84, Lund, Sweden.|Lund Epilepsy Center, Lund University, SE-221 85, Lund, Sweden.
authors.forename: Una
authors.initials: U
authors.lastname: Avdic
authors.affiliation: Division of Ophthalmology, Department of Clinical Sciences, Lund University, SE-221 85, Lund, Sweden.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Skoug
authors.affiliation: Inflammation and Stem Cell Therapy Group, Division of Clinical Neurophysiology, Lund University, BMC A11, Sölvegatan 17, SE-221 84, Lund, Sweden.|Lund Epilepsy Center, Lund University, SE-221 85, Lund, Sweden.
authors.forename: Idrish
authors.initials: I
authors.lastname: Ali
authors.affiliation: Inflammation and Stem Cell Therapy Group, Division of Clinical Neurophysiology, Lund University, BMC A11, Sölvegatan 17, SE-221 84, Lund, Sweden.|Lund Epilepsy Center, Lund University, SE-221 85, Lund, Sweden.
authors.forename: Deepti
authors.initials: D
authors.lastname: Chugh
authors.affiliation: Division of Ophthalmology, Department of Clinical Sciences, Lund University, SE-221 85, Lund, Sweden.
authors.forename: Ulrica Englund
authors.initials: UE
authors.lastname: Johansson
authors.affiliation: Inflammation and Stem Cell Therapy Group, Division of Clinical Neurophysiology, Lund University, BMC A11, Sölvegatan 17, SE-221 84, Lund, Sweden. Christine.Ekdahl_Clementson@med.lu.se.|Lund Epilepsy Center, Lund University, SE-221 85, Lund, Sweden. Christine.Ekdahl_Clementson@med.lu.se.
authors.forename: Christine T
authors.initials: CT
authors.lastname: Ekdahl
mesh_terms: D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D015703:Antigens, CD / Q000378:metabolism; D000073883:CX3C Chemokine Receptor 1; D002135:Calcium-Binding Proteins / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D016207:Cytokines / Q000378:metabolism*; D004195:Disease Models, Animal; D004558:Electric Stimulation / Q000009:adverse effects; D005123:Eye / Q000276:immunology* / Q000378:metabolism / Q000473:pathology*; D005452:Fluoresceins / Q000493:pharmacokinetics; D007839:Functional Laterality; D006624:Hippocampus / Q000528:radiation effects; D008297:Male; D008840:Microfilament Proteins / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009457:Neuroglia / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D019707:Receptors, Chemokine / Q000276:immunology; D013226:Status Epilepticus / Q000209:etiology / Q000276:immunology* / Q000473:pathology* / Q000503:physiopathology; D014795:Visual Pathways / Q000187:drug effects / Q000502:physiology
chemical_list: C100745:Aif1 protein, rat; D000906:Antibodies; D015703:Antigens, CD; D000073883:CX3C Chemokine Receptor 1; C516305:CX3CR1 protein, rat; D002135:Calcium-Binding Proteins; D016207:Cytokines; D005452:Fluoresceins; D008840:Microfilament Proteins; D009419:Nerve Tissue Proteins; D019707:Receptors, Chemokine; C435731:fluoro jade
keywords: Astrocytes; Brain; Epilepsy; Inflammation; Microglia; Retina