Expression and activity of thimet oligopeptidase (TOP) are modified in the hippocampus of subjects with temporal lobe epilepsy (TLE).
OBJECTIVE
Thimet oligopeptidase (TOP) is a metalloprotease that has been associated with peptide processing in several nervous system structures, and its substrates include several peptides such as bradykinin, amyloid beta (Aβ), and major histocompatibility complex (MHC) class I molecules. As shown previously by our research group, patients with temporal lobe epilepsy (TLE) have a high level of kinin receptors as well as kallikrein, a kinin-releasing enzyme, in the hippocampus.


METHODS
In this study, we evaluated the expression, distribution, and activity of TOP in the hippocampus of patients with TLE and autopsy-control tissues, through reverse-transcription polymerase chain reaction (RT-PCR), enzymatic activity, Western blot, and immunohistochemistry. In addition, hippocampi of rats were analyzed using the pilocarpine-induced epilepsy model. Animals were grouped according to the epilepsy phases defined in the model as acute, silent, and chronic.


RESULTS
Increased TOP mRNA expression, decreased protein levels and enzymatic activity were observed in tissues of patients, compared to control samples. In addition, decreased TOP distribution was also visualized by immunohistochemistry. Similar results were observed in tissues of rats during the acute phase of epilepsy model. However, increased TOP mRNA expression and no changes in immunoreactivity were found in the silent phase, whereas increased TOP mRNA expression and increased enzymatic activity were observed in the chronic phase.


CONCLUSIONS
The results show that these alterations could be related to a failure in the mechanisms involved in clearance of inflammatory peptides in the hippocampus, suggesting an accumulation of potentially harmful substances in nervous tissue such as Aβ, bradykinin, and antigenic peptides. These accumulations could be related to hippocampal inflammation observed in TLE subjects.
Neurology/Neurosurgery Department, Federal University of São Paulo (UNIFESP), São Paulo, Brazil.
Priscila Santos Rodrigues
PSR
Simões
Psychobiology Department, Federal University of São Paulo (UNIFESP), São Paulo, Brazil.
Bruna
B
Visniauskas
Neurology/Neurosurgery Department, Federal University of São Paulo (UNIFESP), São Paulo, Brazil.
Sandra Regina
SR
Perosa
Neurology/Neurosurgery Department, Federal University of São Paulo (UNIFESP), São Paulo, Brazil.
Elza Márcia Targas
EMT
Yacubian
Neurology/Neurosurgery Department, Federal University of São Paulo (UNIFESP), São Paulo, Brazil.
Ricardo
R
Centeno
Pathology Department, Heart Institute-Medicine School University of São Paulo, (INCOR-FMUSP), São Paulo, Brazil.
Mauro
M
Canzian
Department of Medical Genetics, University of Campinas (UNICAMP), Campinas, Brazil.
Iscia
I
Lopes-Cendes
Department of Medical Genetics, University of Campinas (UNICAMP), Campinas, Brazil.
Claudia Vianna
CV
Maurer Morelli
Image and Diagnostic Department, Federal University of São Paulo (UNIFESP), São Paulo, Brazil.
Henrique
H
Carrete
Neurology/Neurosurgery Department, Federal University of São Paulo (UNIFESP), São Paulo, Brazil.
Esper Abrão
EA
Cavalheiro
Psychobiology Department, Federal University of São Paulo (UNIFESP), São Paulo, Brazil.
Sergio
S
Tufik
Psychobiology Department, Federal University of São Paulo (UNIFESP), São Paulo, Brazil.
Jair Ribeiro
JR
Chagas
Department of Biochemistry, Federal University of São Paulo ( UNIFESP), São Paulo, Brazil.
Maria da Graça
MDG
Naffah Mazzacoratti
D000328:Adult; D000818:Animals; D038481:Anterior Temporal Lobectomy; D004195:Disease Models, Animal; D004833:Epilepsy, Temporal Lobe / Q000235:genetics* / Q000473:pathology* / Q000601:surgery; D005260:Female; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics; D006624:Hippocampus / Q000473:pathology* / Q000601:surgery; D006801:Humans; D007274:Injections, Intraperitoneal; D008297:Male; D008666:Metalloendopeptidases / Q000235:genetics*; D008875:Middle Aged; D010862:Pilocarpine; D012333:RNA, Messenger / Q000235:genetics*; D051381:Rats; D012598:Sclerosis; D013702:Temporal Lobe / Q000473:pathology; D055815:Young Adult
D012333:RNA, Messenger; D010862:Pilocarpine; D008666:Metalloendopeptidases; C022510:thimet oligopeptidase
Mesial sclerosis; Pilocarpine; Temporal lobe epilepsy; Thimet oligopeptidase