Early molecular and behavioral response to lipopolysaccharide in the WAG/Rij rat model of absence epilepsy and depressive-like behavior, involves interplay between AMPK, AKT/mTOR pathways and neuroinflammatory cytokine release.

The mammalian target of rapamycin (mTOR) pathway has been recently indicated as a suitable drug target for the prevention of epileptogenesis. The mTOR pathway is known for its involvement in the control of the immune system. Since neuroinflammation is recognized as a major contributor to epileptogenesis, we wished to examine whether the neuroprotective effects of mTOR modulation could involve a suppression of the neuroinflammatory process in epileptic brain. We have investigated the early molecular mechanisms involved in the effects of intracerebral administration of the lipopolysaccharide (LPS) in the WAG/Rij rat model of absence epilepsy, in relation to seizure generation and depressive-like behavior; we also tested whether the effects of LPS could be modulated by treatment with rapamycin (RAP), a specific mTOR inhibitor. We determined, in specific rat brain areas, levels of p-mTOR/p-p70S6K and also p-AKT/p-AMPK as downstream or upstream indicators of mTOR activity and tested the effects of LPS and RAP co-administration. Changes in the brain levels of pro-inflammatory cytokines IL-1ß and TNF-α and their relative mRNA expression levels were measured, and the involvement of nuclear factor-κB (NF-κB) was also examined in vitro. We confirmed that RAP inhibits the aggravation of absence seizures and depressive-like/sickness behavior induced by LPS in the WAG/Rij rats through the activation of mTOR and show that this effect is correlated with the ability of RAP to dampen and delay LPS increases in neuroinflammatory cytokines IL-1ß and TNF-α, most likely through inhibition of the activation of NF-κB. Our results suggest that such a mechanism could contribute to the antiseizure, antiepileptogenic and behavioral effects of RAP and further highlight the potential therapeutic usefulness of mTOR inhibition in the management of human epilepsy and other neurological disorders. Furthermore, we show that LPS-dependent neuroinflammatory effects are also mediated by a complex interplay between AKT, AMPK and mTOR with specificity to selective brain areas. In conclusion, neuroinflammation appears to be a highly coordinated phenomenon, where timing of intervention may be carefully evaluated in order to identify the best suitable target.

Calcium channel antibodies in patients with absence epilepsy.

Autoimmunity has aroused interest in the last years as a contributory mechanism of epilepsy, especially in epilepsies with unknown cause or therapy resistance. Since the relationship of absence epilepsy (AE) with calcium channels is well established, we aimed to investigate related antibodies in patients diagnosed with AE. Consecutive patients with typical absence seizures having either childhood absence epilepsy (CAE) or juvenile absence epilepsy (JAE) with generalized spike and wave discharges on electroencephalography (EEG) were included after their consent. The patients were diagnosed according to the International League Against Epilepsy (ILAE) 2010 criteria. Antibodies against P-Q type voltage gated calcium channels (VGCC) and T-type VGCC subunit Cav3.2 (encoded by the CACNA1H gene) were investigated by RIA and ELISA, respectively. We searched for these antibodies in 32 patients with AE and 53 patients with focal epilepsy of unknown cause (FEOUC) as the disease control group; furthermore, 30 healthy persons served as the healthy controls. Eleven patients (34.3%) with AE had CAE and the remaining patients had JAE. Only a 47-year-old female FEOUC patient, who also had systemic lupus erythematosus with normal MRI scans showed antibodies against P-Q type VGCC, whereas no antibody positivity could be found in other FEOUC and AE patients and healthy controls. Our results might suggest that calcium channel antibodies do not play an important role in the pathophysiology of AE. Further studies with larger groups of other epileptic syndromes are needed to confirm our results.

Facilitation of spike-wave discharge activity by lipopolysaccharides in Wistar Albino Glaxo/Rijswijk rats.

In normal rats the proinflammatory cytokines like interleukin-1beta, interleukin-6, which are induced by bacterial lipopolysaccharides, are able to control thalamo-cortical excitability by exerting strong effects on physiological synchronization such as sleep and on pathological synchronization like that in epileptic discharges. To investigate whether proinflammatory cytokines or lipopolysaccharides could modulate absence seizures resulting from a very different generator mechanism than the already investigated bicuculline-, kindling- and kainate-induced seizures, we used a genetically epileptic Wistar Albino Glaxo/Rijswijk rat strain, which is spontaneously generating high voltage spike-wave discharges. Wistar Albino Glaxo/Rijswijk rats responded with an increase of the number of spike-wave discharges to lipopolysaccharide injection (from 10 microg/kg to 350 microg/kg). Repetitive administration of 350 microg/kg lipopolysaccharides daily for 5 days increased the number of spike-wave discharges on the first, second and third days but the number of spike-wave discharges returned to the control value on day 5, at the 5th injection of lipopolysaccharides, showing a tolerance to lipopolysaccharides. The lipopolysaccharide-induced increase in spike-wave discharges was not directly correlated with the elevation of the core body temperature, as it is in febrile seizures, although lipopolysaccharide induced prostaglandin and is clearly pyrogenic at the doses used. Indomethacin, the prostaglandin synthesis inhibitor, efficiently blocked lipopolysaccharide-induced enhancement of spike-wave discharge genesis suggesting that the spike-wave discharge facilitating effect of lipopolysaccharides involves induction of cyclooxygenase 2 and subsequent synthesis and actions of prostaglandin E2. Low dose (40 mg/kg, i.p.) of competitive N-methyl-d-aspartate receptor antagonist 2-amino-5-phosphonopentanoic acid, and low dose of lipopolysaccharide (20 microg/kg) showed a synergistic interaction to increase the number of spike-wave discharges, whereas at supramaximal doses of lipopolysaccharide and the N-methyl-D-aspartate antagonist no synergy was present. The data reveal a functional connection between absence epileptic activity and lipopolysaccharide induction of prostaglandin synthesis and prostaglandin action and suggest some common cellular targets in epilepsy and lipopolysaccharide-induced inflammation.

A dysbalanced immune system in cryptogenic Lennox-Gastaut syndrome.

In children with cryptogenic Lennox-Gastaut syndrome we found a functionally impaired humoral immune response to a primary antigen (haemocyanin), despite signs of a triggered immune system consisting of elevated IgG concentrations. This combination of immunological findings, considered to be the expression of a dysbalanced-triggered as well as functionally impaired-immune system, has also been described in an auto-immune disease like systemic lupus erythaematodes in humans, and in genetically epilepsy-prone rats. The interactions between the immune system and the nervous system in Lennox-Gastaut syndrome will be discussed.

[High-dose immunoglobulin treatment of epilepsy in children]. / Hochdosierte Immunglobulinbehandlung der Epilepsie bei Kindern.

High-dose, intravenously administered immunoglobulins have been successfully applied to a few cases of childhood epilepsy and led to a reduction of the seizure frequency in a number of studies. In the present study 4 patients with myoclonic-astatic petit mal or myoclonic absence were treated with intravenously administered immunoglobulins (400 mg/kg for 5 days). Deterioration occurred in 1 patient, 1 patient showed no effect, and 2 patients showed a partial and transient response. Theoretically, the rationale for immunoglobulin therapy in epilepsy is based on the assumption of autoimmune mechanisms as being the underlying pathogenesis. However, a review of the literature showed that the few studies available differ in the forms of epilepsy treated and the effects obtained. No study correlated the effects of immunoglobulin administration with a presumptive autoimmune disorder. As a result, high-dose intravenous immunoglobulin treatment of childhood epilepsy remains empirical and the group of patients who might benefit from such a treatment continues to be poorly defined.

Impairment of polymorphonuclear leucocyte function during therapy with synthetic ACTH in children affected by epileptic encephalopathies.

Therapy with synthetic ACTH (zinc tetracosactide) in children affected by epileptic encephalopathy is often associated with a large number of infectious complications. We studied the phagocytic activity of polymorphonuclear leucocytes (PMN) in 9 children with West or Lennox-Gastaut syndrome, measuring PMN superoxide anion production during the phagocytosis of particles of Zymosan and after phorbol myristate acetate (PMA) stimulation. The test was performed before, during and after therapy with zinc tetracosactide (0.02 mg/kg/day for 15 days). At the same time plasma immunoglobulins, C3, C4, C3 activator and cortisol were determined. During treatment PMN phagocytic function was significantly reduced but returned to normal levels after suspension of therapy. The other hematological parameters considered remained within the normal range. During the follow-up of the patients we observed 15 infectious episodes (3 mucocutaneous candidiasis, 2 enterocolitis, 4 urinary tract infections, 1 otitis media, 3 bronchiolitis, 2 pneumonia). One of the patients died of a bilateral pneumonia. Three children were treated with ACTH on alternating days. In these patients PMN phagocytic activity was less impaired and 2 infectious episodes rapidly resolved. Alternate day ACTH therapy seems to be preferable.

Neurological and electroencephalographic abnormalities after febrile seizures. Possible association with cytomegalovirus.

In order to assess the possible association of cytomegalovirus (CMV) with cerebral damage, 65 children aged between 2 and 10 years were tested for CMV isolation and antibody status. All of them had previously presented one or more episodes of febrile convulsions. At the time of our study, they were grouped according to their clinical features and electroencephalogram (EEG). 21 had typical and/or atypical absence attacks with 3 c/s spike-wave EEG (primary generalized epilepsy), 21 presented febrile seizures and spontaneous fits with focal EEG abnormalities, 23 had no seizures and a normal EEG. We performed the same investigation in 41 healthy children. The study showed a similar isolation rate of CMV in healthy subjects and in patients without neurological and EEG alterations, while a significantly higher isolation rate was observed in the groups with neurological and EEG abnormalities. As for serology, no significant difference was observed between the four groups, although the positivity rate of the healthy children was lower than in the other three groups. The study suggests a possible association of CMV with neurological and EEG abnormalities after febrile seizures.