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Individual hippocampal subfield assessment indicates that matrix macromolecules and gliosis are key elements for the increased T2 relaxation time seen in temporal lobe epilepsy
Author(s) -
PeixotoSantos Jose Eduardo,
Kandratavicius Ludmyla,
Velasco Tonicarlo Rodrigues,
Assirati Joao Alberto,
Carlotti Carlos Gilberto,
Scandiuzzi Renata Caldo,
Salmon Carlos Ernesto Garrido,
Santos Antonio Carlos dos,
Leite Joao Pereira
Publication year - 2017
Publication title -
epilepsia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.687
H-Index - 191
eISSN - 1528-1167
pISSN - 0013-9580
DOI - 10.1111/epi.13620
Subject(s) - subiculum , astrogliosis , hippocampal formation , gliosis , glial fibrillary acidic protein , pathology , neuroscience , hippocampal sclerosis , hippocampus , fascia dentata , temporal lobe , medicine , chemistry , epilepsy , biology , dentate gyrus , central nervous system , immunohistochemistry
Summary Objective Increased T2 relaxation time is often seen in temporal lobe epilepsy (TLE) with hippocampal sclerosis. Water content directly affects the effective T2 in a voxel. Our aim was to evaluate the relation between T2 values and two molecules associated with brain water homeostasis aquaporin 4 ( AQP 4) and chondroitin sulfate proteoglycan ( CSPG ), as well as cellular populations in the hippocampal region of patients with TLE . Methods Hippocampal T2 imaging and diffusion tensor imaging ( DTI ) were obtained from 42 drug‐resistant patients with TLE and 20 healthy volunteers (radiologic controls, RC s). A similar protocol (ex vivo) was applied to hippocampal sections from the same TLE cases and 14 autopsy control hippocampi (histologic and radiologic controls, HRC s), and each hippocampal subfield was evaluated. Hippocampal sections from TLE cases and HRC controls were submitted to immunohistochemistry for neurons (neuron nuclei [NeuN]), reactive astrocytes (glial fibrillary acidic protein [GFAP]), activated microglia (human leukocyte antigen‐D–related [HLA‐ DR ]), polarized AQP 4, and CSPG . Results Patients with TLE had higher in vivo and ex vivo hippocampal T2 relaxation time. Hippocampi from epilepsy cases had lower neuron density, higher gliosis, decreased AQP 4 polarization, and increased CSPG immunoreactive area. In vivo relaxation correlated with astrogliosis in the subiculum and extracellular CSPG in the hilus. Ex vivo T2 relaxation time correlated with astrogliosis in the hilus, CA 4, and subiculum, and with microgliosis in CA 1. The difference between in vivo and ex vivo relaxation ratio correlated with mean diffusivity and with the immunopositive area for CSPG in the hilus. Significance Our data indicate that astrogliosis, microgliosis, and CSPG expression correlate with the increased T2 relaxation time seen in the hippocampi of patients with TLE .