Persistent astroglial DNA methylation and downregulation of homeostatic genes in a lithium-pilocarpine model of Temporal Lobe Epilepsy (TLE).

GOMEZ DD1, ROSSI A1, VILLARREAL A1, D`ALESSIO L, RAMOS AJ

Mar del Plata

Congreso; Reunión conjunta SAI-SAIC-SAFE-Nanomed; 2022

Sociedad Argentina de Investigación Clínica

Retrospective studies in TLE patients have shown the common feature of an initial precipitating injury (IPE) in early childhood, usually complex febrile with Status Epilepticus (SE). The IPE is usually followed by a silent period of years until chronic epilepsy emerges. We have previously shown extensive neuroinflammation and reactive astrogliosis in this silent period in the Li-pilocarpine rodent model of TLE (Rossi et al, 2013; 2017). Here, we studied if extensive astrogliosis induce epigenetic alterations in DNA methylation and homeostatic genes expression. Adult male Wistar rats (220-240 g) were treated with 127 mg/kg LiCl and 18 h later they received 30 mg/kg pilocarpine ip. Status Epilepticus (SE, IPE) were allowed to persist for 15 min and then seizures were stopped by 10 mg/kg diazepam. At different times during the latency period (7, 21 or 35 DPSE, days post SE), the abundance of 5 methyl Cytosine (5mC) in the astroglial DNA and the expression of several astroglial homeostatic genes (Kir4.1, aquaporin 4 (AQP4), glutamine synthetase (GS), In addition, we analyzed by RT-qPCR the changes in the expression of DNA methyl transferases DNMT1 and DNMT3a. Level of astroglial 5mC was also studied in hippocampal sections of surgical resections of TLE patients. We observed a global hypermethylation in astrocytes, accompanied by increased expression of DNMT1/DNMT3a and a reduction in the expression of GS, Kir4.1 and AQP4 at 7, 21 and persisted until 35 DPSE. Reactive astrogliosis and increased 5mC in astrocytes were also observed in the hippocampal sections of TLE patients. We conclude that astrocytes show persistent downregulation of homeostatic genes during the latency period that follows an experimental IPE. This correlates with increased 5mC in the DNA that may be responsible for the homeostatic gene repression. Supported by grants: PICT 2017-2203; UBACYT; PIP CONICET 479