Immunotherapy by targeting of VGKC complex for seizure control and prevention of cognitive impairment in a mouse model of epilepsy

Abstract

Epilepsy is a type of refractory neurologic disorder mental disease, which is associated with cognitive impairments and memory dysfunction. However, the potential mechanisms of epilepsy are not well understood. Previous evidence has identified the voltage gated potassium channel complex (VGKC) as a target in various cohorts of patients with epilepsy. In the present study, the efficacy of an antibody against VGKC (anti‑VGKC) for the treatment of epilepsy in mice was investigated. A mouse model of lithium‑pilocarpine temporal lobe epilepsy was established and anti‑VGKC treatment was administered for 30 days. Memory impairment, anxiety, visual attention, inhibitory control and neuronal loss were measured in the mouse model of lithium‑pilocarpine temporal lobe epilepsy. The results revealed that epileptic mice treated with anti‑VGKC were able to learn the task and presented attention impairment, even a tendency toward impulsivity and compulsivity. It was also exhibited that anti‑VGKC treatment decreased neuronal loss in structures classically associated with attentional performance in hippocampus. Mice who received Anti‑VGKC treatment had inhibited motor seizures and hippocampal damage as compared with control mice. In conclusion, these results indicated that anti‑VGKC treatment may present benefits for improvements of the condition of motor attention impairment and cognitive competence, which suggests that VGKC may be a potential target for the treatment of epilepsy.

Figure 1.

Schematic of the experimental procedures applied for anti-VGKC treatment in mice with epilepsy. VGKC, voltage gated potassium channel complex; FDG-PET, fluorodeoxyglucose-positron emission tomography; EEG, electroencephalography.

Figure 2.

Expression of VGKC and the effects anti-VGKC on temporal lobe epileptiform spiking in vivo. (A) Anti-VGKC decreased mRNA levels of VGKC in PBMCs in mice with epilepsy. (B) Anti-VGKC decreased serum levels of VGKC in mice with epilepsy. (C) Relative VGKC mRNA levels in the hippocampus between the anti-VGKC and control group in mice with epilepsy. (D) VGKC levels in CSF between the anti-VGKC and control groups in mice with epilepsy. (E) The affinity of anti-VGKC with VGKC determined by ELISA. Neuroprotective gene expression of (F) Foxp-2, (G) EB and (H) SxIP in hippocampus cells in epileptic mice following treatment with anti-VGKC or control. Data are presented as the mean ± standard deviation (n=5/group). **P<0.01, as indicated. Health group, positive control; VGKC, voltage gated potassium channel complex; PBMCs, peripheral blood mononuclear cells; CSF, cerebrospinal fluid; Foxp-2, forkhead-BOX P2; EB, microtubule end binding.

Figure 3.

Relaxation effects of anti-VGKC on temporal lobe epileptiform spiking in mice with epilepsy. (A) Normalized spike rate plotted as a function of days of treatment with anti-VGKC or control. (B) Mice behaviors in the anti-VGKC and control groups were scored by STESS. (C) EEG differences were compared between the anti-VGKC and control mice following the 30-day treatment period. (D) Examples of time-frequency (Morlet wavelets) power spectra from representative epileptic mice in the anti-VGKC and control groups during the 30-day treatment period. Power scale (right y axis) refers to µV²/Hz. (E) Total seizure duration in epileptic mice following treatment with anti-VGKC or control. (F) Whole traveled distance in the open field activity test. The whole traveled distance in the open field tests were different between the anti-VGKC and control groups. Data are presented as the mean ± standard deviation (n=4/group) **P<0.01, as indicated. VGKC, voltage gated potassium channel complex; STESS, Status Epilepticus Severity Score.

Figure 4.

Improvement in the efficacy of anti-VGKC on behaviors for mice with epilepsy. (A) The Morris water maze test evaluated the escape latency between the anti-VGKC and control groups. (B) Volumetric hippocampal ratio of TIV between the anti-VGKC and control groups. (C) Seizure frequency in mice with epilepsy following treatment with anti-VGKC. (D) The coordinate abilities following the 30-day treatment period of anti-VGKC. (E) Spiking events of faciobrachial dystonic seizures in epileptic mice following anti-VGKC treatment (53%) compared with the control group. (F) Representative electroencephalography in experimental mice in the hippocampus of anti-VGKC- or control-treated mice on day 30. Data are presented as the mean ± standard deviation (n=4/group). **P<0.01, as indicated. VGKC, voltage gated potassium channel complex; TIV, total intracranial volume.

Figure 5.

Target treatment of anti-VGKC on the hippocampus of mice with epilepsy. (A) Hippocampus excitability was downregulated following 4-week treatment with anti-VGKC compared with the control group. (B) Neuroprotective protein expression of Foxp-2, EB and SxIP were upregulated in hippocampus cells following anti-VGKC treatment in mice with epilepsy (magnification, ×20). (C) Anti-VGKC treatment significantly improved the survival of epilepsy-bearing mice compared with the control group. (D) Discharge sites (indicated by arrows) were decreased in the temporal lobe following anti-VGKC treatment in vivo compared with the control group (magnification, ×10). (E) Hippocampus treated with anti-VGKC showed dispersion of the pyramidal cell layer and more neurons by thionin staining (magnification, ×20). (F) Anti-VGKC treatment significantly lowered prospective observation with epilepsy determined by Rankin score. (G) Anti-VGKC treatment significantly improved cognitive competence by Path efficiency measures. (H) Anti-VGKC treatment significantly improved the damaged neurons in the hippocampus analyzed by histology and immunofluorescence (magnification, ×20). Data are presented as the mean ± standard deviation (n=6/group. **P<0.01, as indicated. VGKC, voltage gated potassium channel complex; Foxp-2, forkhead-BOX P2; EB, microtubule end binding.